JP2008062691A - Hydraulic drive type working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the transmission efficiency of HST formed by a hydraulic pump body and both hydraulic motor bodies in a hydraulic drive type working vehicle in which a front side hydraulic motor body for operatively driving a front side drive wheel and a rear side hydraulic motor body for operatively driving a rear side drive wheel are fluid-connected to a single common hydraulic pump body in series. <P>SOLUTION: The hydraulic motor body positioned at an upstream side in a flowing direction of HST operation oil at advancement of the vehicle of the both hydraulic motor bodies is constituted such that a free end of a piston is engaged with the corresponding swash plate through a shoe. Preferably, the hydraulic motor body positioned at a downstream side in the flowing direction of the HST operation oil at advancement of the vehicle of the both hydraulic motor bodies is constituted such that the free end of the piston is engaged with the corresponding swash plate through a thrust bearing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulically driven work vehicle including a front hydraulic motor main body and a rear hydraulic motor main body fluidly connected in series to a single common hydraulic pump main body.

  For a single common hydraulic pump body that is operatively driven by a drive source, a front hydraulic motor body that operatively drives the front drive wheels and a rear hydraulic motor that operatively drives the rear drive wheels 2. Description of the Related Art Conventionally, a hydraulically-driven work vehicle in which a main body is fluidly connected in series is known (for example, see Patent Document 1 below).

  Such a hydraulically driven working vehicle is configured to hydraulically drive both the front hydraulic motor main body and the rear hydraulic motor main body by the single hydraulic pump main body, while driving the front drive wheel or the rear drive. Even if one of the wheels gets stuck in a groove or the like and the corresponding hydraulic motor main body is in a no-load or low-load state, the HST hydraulic oil can be appropriately flowed to the other high-load hydraulic motor main body. There is.

However, in the conventional hydraulically driven work vehicle, the transmission efficiency when converting the hydraulic driving force from the hydraulic pump main body into the mechanical rotational driving force of the front hydraulic motor main body and the rear hydraulic motor main body. There is room for improvement in terms of HST transmission efficiency.
US Pat. No. 6,732,828

  The present invention has been made in view of the prior art, and a front hydraulic motor body that operatively drives a front drive wheel with respect to a single common hydraulic pump body that is operatively driven by a drive source. And a hydraulically driven working vehicle in which a hydraulic hydraulic main body that operatively drives the rear drive wheels is fluidly connected in series, wherein the hydraulic pump main body, the front hydraulic motor main body, and the rear hydraulic pressure An object is to provide a hydraulically driven working vehicle having a simple structure capable of improving the transmission efficiency of the HST formed by the motor body.

  In order to achieve the above object, the present invention provides a drive source, front drive wheels and rear drive wheels disposed on the vehicle front side and rear side, respectively, and a front hydraulic motor disposed on the vehicle front side. A main body, a rear hydraulic motor main body disposed on the rear side of the vehicle, and operatively driven by the drive source, form an HST in cooperation with the front hydraulic motor main body and the rear hydraulic motor main body. And a hydraulic drive body configured to operatively drive the front drive wheel and the rear drive wheel by rotational outputs of the front hydraulic motor body and the rear hydraulic motor body, respectively. The front hydraulic motor main body and the rear hydraulic motor main body are fluidly connected in series to the hydraulic pump main body, and the front hydraulic motor main body and the The hydraulic motor body located on the upstream side in the flow direction of the HST hydraulic oil in the forward direction of the vehicle among the side hydraulic motor bodies is a hydraulic drive type in which the free end of the piston is engaged with the corresponding swash plate via a shoe. Provide working vehicles.

  Preferably, among the front hydraulic motor main body and the rear hydraulic motor main body, the hydraulic motor main body positioned on the downstream side in the flow direction of the HST hydraulic fluid when the vehicle moves forward is such that the free end of the piston is supported via a thrust bearing. Engaged with the swash plate.

  Preferably, when the working machine that is operatively driven by the power from the drive source is disposed outward in the vehicle front-rear direction than either the front drive wheel or the rear drive wheel, Of the front hydraulic motor main body and the rear hydraulic motor main body, the hydraulic motor main body on the side close to the work implement can be positioned upstream in the flow direction of the HST hydraulic oil when the vehicle moves forward.

At least one of the front hydraulic motor main body and the rear hydraulic motor main body outputs a reduction gear mechanism that reduces its rotation output and a rotation output reduced by the reduction gear mechanism toward a corresponding drive wheel. A wheel motor device can be configured together with an output member and a casing that houses the hydraulic motor main body and the reduction gear mechanism.
In such a configuration, preferably, the casing is configured such that an oil-storable motor space that houses the hydraulic motor body is liquid-tightly divided with respect to a gear space that houses the reduction gear mechanism, and At least a part of the oil discharged from the auxiliary pump body that is rotatively driven by rotational power from the driving source may return to the suction side of the auxiliary pump body through the motor space.

  More preferably, an external tank serving as an oil source for the auxiliary pump body, a circulation line forming a circulation path including the external tank, the auxiliary pump body, and the motor space, and an oil cooler interposed in the circulation line And may be further provided.

The circulation line has one end fluidly connected to the external tank and the other end fluidly connected to the suction side of the auxiliary pump body, and one end fluidly connected to the discharge side of the auxiliary pump body. And a discharge line whose other end is fluidly connected to the motor space, and a return line whose one end is fluidly connected to the motor space and whose other end is fluidly connected to the external tank.
In one aspect, the discharge line is configured to supply hydraulic oil to the hydraulic actuator and supply return oil from the hydraulic actuator to the motor space.
More preferably, the discharge line is configured to supply surplus oil for the hydraulic actuator to the motor space in addition to return oil from the hydraulic actuator.
In another aspect, the discharge line is configured to supply hydraulic oil to the hydraulic actuator and supply surplus oil for the hydraulic actuator to the motor space.

  More preferably, the oil cooler is inserted into the return line, one end is fluidly connected to the discharge line, and the other end is fluidly connected to the return line downstream in the oil flow direction from the oil cooler. And a relief valve interposed in the bypass line so as to set a maximum hydraulic pressure of the discharge line.

In the various configurations, the common hydraulic pump main body is a variable displacement type, and one of the vehicle front side hydraulic motor main body and the vehicle rear side hydraulic motor main body is a fixed volume type cooperating with a fixed swash plate, and the other Is a variable volume type that cooperates with the movable swash plate.
In such a configuration, preferably, in the motor case housing the variable displacement hydraulic motor main body, a support shaft and a base end portion are supported so as not to rotate relative to the support shaft, and a distal end portion thereof is the movable swash plate. A swing arm that engages with the side of the movable swash plate, a biasing member that urges the movable swash plate to one side about a swing center, and a swing of the movable swash plate biased by the biasing member. A reference position setting member is provided that defines a swing end on one side around the center of movement.
More preferably, the reference position setting member can change the position of the swing end from the outside of the motor case.
Alternatively or in addition, the end of the support shaft opposite to the side supporting the swing arm is extended outward of the motor case, and the outer end of the support shaft is Accordingly, the movable swash plate can be operated to the other side around the swing center against the biasing force of the biasing member.

  According to the hydraulically operated working vehicle of the present invention, the front hydraulic motor main body that drives the front drive wheels located on the vehicle front side and the rear hydraulic motor main body that drives the rear drive wheels located on the vehicle rear side. Are connected in series to the common hydraulic pump body, and the piston of the hydraulic motor body located on the upstream side of the flow direction of the HST hydraulic oil in the forward direction of the vehicle among the both hydraulic motor bodies corresponds to the corresponding diagonal through the shoe. Since it is configured to engage with the plate, the transmission efficiency of the HST formed by the hydraulic pump body and the both hydraulic motor bodies can be improved efficiently.

  If the piston of the hydraulic motor body located on the downstream side in the flow direction of the HST hydraulic oil in the forward direction of the HST hydraulic oil is engaged with the corresponding swash plate via a thrust bearing, the cost increases. HST transmission efficiency can be improved while preventing as much as possible.

  In the configuration in which a work machine that is operatively driven by power from the drive source is disposed outward in the vehicle front-rear direction from either the front drive wheel or the rear drive wheel, the both hydraulic pressures If the hydraulic motor body on the side close to the working machine among the motor bodies is configured to be upstream of the flow direction of the HST hydraulic fluid when the vehicle moves forward, the hydraulic pressure on the side on which the load caused by the working machine acts greatly It can effectively prevent the transmission efficiency of the motor body from deteriorating.

When at least one of the hydraulic motor bodies forms a wheel motor device together with the reduction gear mechanism, the oil-storable motor space that houses the hydraulic motor body is liquid with respect to the gear space that houses the reduction gear mechanism. If the casing of the wheel motor device is configured so as to be densely divided, the lubricating oil is used in the HST hydraulic oil while using viscous oils suitable for the HST hydraulic oil and the lubricating oil for the reduction gear mechanism, respectively. It can be effectively prevented from being mixed in.
Further, at least a part of the oil discharged from the auxiliary pump body that is rotatively driven by rotational power from the drive source returns to the suction side of the auxiliary pump body through the motor space. For example, the oil stored in the motor space can be actively circulated, thereby preventing leakage oil from the hydraulic motor main body from staying in the motor space and cooling efficiency of the hydraulic motor main body. Can be improved.

  Further, in the configuration including an external tank serving as an oil source for the auxiliary pump body, if an oil cooler is inserted in a circulation line that forms a circulation path including the external tank, the auxiliary pump body, and the motor space, The cooling efficiency of the hydraulic motor body can be further improved.

  A discharge line constituting a part of the circulation line, wherein one end is fluidly connected to the discharge side of the auxiliary pump body and the other end is fluidly connected to the motor space; And supplying the hydraulic oil to the motor space with the return oil from the hydraulic actuator and / or the return oil from the hydraulic actuator, while improving the cooling efficiency of the hydraulic motor body, The pressure oil from the auxiliary pump body can be used effectively.

  The oil cooler is inserted in the return line, and one end is fluidly connected to the discharge line, and the other end is fluidly connected to the return line on the downstream side of the oil cooler in the oil flow direction. And a relief valve inserted in the bypass line so as to set the maximum hydraulic pressure of the discharge line, an excessive hydraulic pressure is applied to the oil cooler when the hydraulic pressure in the motor space increases. Can be effectively prevented from acting. Therefore, the oil cooler can be effectively prevented from being damaged.

Embodiment 1
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 3 show a side view, a plan view, and a hydraulic circuit diagram of a working vehicle 1A to which the present embodiment is applied.

In the present embodiment, the working vehicle 1A is an articulate riding lawn mower as shown in FIGS.
Specifically, the working vehicle 1A includes a first frame 11 disposed on one side in the vehicle front-rear direction (front in the present embodiment) and the other side in the vehicle front-rear direction (rear in the present embodiment). A second frame 12 disposed on the first frame 11 and swingably connected to the first frame 11 about a pivot shaft 10 along a substantially vertical direction; A pair of left and right first drive wheels 21L and 21R disposed on the vehicle, a pair of left and right second drive wheels 22L and 22R disposed on the other side in the vehicle longitudinal direction, and a drive source supported by the second frame 12 30, a hydraulic pump unit 40 having at least one hydraulic pump body 420 operatively driven by the drive source 30, and at least one hydraulic motor book for driving the pair of left and right first drive wheels 21 </ b> L and 21 </ b> R. 120, a first axle drive device 50 having at least one hydraulic motor body for driving the first axle drive device 50 connected to the first frame 11 and the pair of left and right second drive wheels 22L, 22R. A second axle driving device 60 having 620, and a second axle driving device 60 coupled to the second frame 12.

  In the present embodiment, as shown in FIGS. 1 to 3, the working vehicle 1 </ b> A further moves the first frame 11 to the second frame in conjunction with a steering member 5 such as a steering wheel that can be manually operated. The hydraulic steering mechanism 70 that swings about the pivot shaft 10 with respect to the frame 12 and the vehicle vehicle front-rear direction outward (frontward in the present embodiment) relative to the first drive wheel 21 And a mower device 80 supported by the first frame 11.

  As shown in FIG. 3, the hydraulic pump unit 40 includes a pump shaft 410 operatively connected to the drive source 30, a hydraulic pump body 420 supported by the pump shaft 410 so as not to rotate relative to the pump shaft 410, and the pump shaft 410. And a pump case 430 that forms a pump space for accommodating the hydraulic pump main body 420.

  The hydraulic pump body 420 cooperates with at least one hydraulic motor body 120 in the first axle drive device 50 and at least one hydraulic motor body 620 in the second axle drive device 60 to form an HST. As described above, the hydraulic motor main bodies 120 and 620 are fluidly connected.

Specifically, the pump case 430 is provided with a pump-side first hydraulic fluid passage 441 and a pump-side second hydraulic fluid passage 442 that are fluidly connected to the hydraulic pump main body 420, as shown in FIG.
Each of the pump-side first hydraulic fluid passage 441 and the pump-side second hydraulic fluid passage 442 has at least one end opened to the outer surface. The opening end portions of the first pump-side hydraulic fluid passage 441 and the second pump-side hydraulic fluid passage 442 form a hydraulic fluid port 441 (P) and a hydraulic fluid port 442 (P), respectively.

In the present embodiment, the hydraulic pump main body 420 is a variable displacement type in which the suction / discharge amount is variable.
That is, the hydraulic pump unit 40 includes an output adjusting member 450 (see FIG. 3) that changes the suction / discharge amount of the hydraulic pump main body 420 based on an external operation in addition to the above-described configuration.
The output adjusting member 450 includes, for example, a movable swash plate (not shown) that defines a piston advance / retreat operation range in the hydraulic pump main body 420 and a movable swash plate that can tilt the movable swash plate. And a control shaft 451 (see FIG. 1) that is operatively connected.

As shown in FIG. 1, the control shaft 451 is operatively connected to a travel shift operation member 15 that can be manually operated via a control arm 455 and a connection member (not shown).
In the present embodiment, the movable swash plate can be tilted in both forward and reverse directions with the neutral position in between.
That is, when the travel speed change operation member 15 is operated in the forward direction, the movable swash plate tilts in the forward direction, and when the travel speed change operation member 15 is operated in the reverse direction, the movable swash plate tilts in the reverse direction. It is supposed to be. In the present embodiment, the speed change operation member 15 is configured as a seesaw pedal type, but it may be a two-pedal type dedicated to forward movement and backward movement.

Further, as shown in FIG. 3, the pump case 430 includes a bypass oil passage 480 communicating between the pump-side first and second hydraulic fluid passages 441 and 442, and one end portion inside the pump case 430. A drain oil passage 485 that is open to the space and a rotary valve 490 that is inserted into the bypass oil passage 480 and that can be externally operated are provided.
The rotary valve 490 communicates the bypass oil passage 480 and the drain oil passage 485 with a shut-off position that shuts off the bypass oil passage 480 and the drain oil passage 485 with respect to the bypass oil passage 480. A communication position for communicating with the bypass oil passage 480 can be taken.

In the working vehicle 1A, as shown in FIG. 3, the hydraulic pump main body 420 includes both the hydraulic motor main body 120 in the first axle driving device 50 and the hydraulic motor main body 620 in the second axle driving device 60. Is hydraulically driven.
A fluid connection structure between the hydraulic pump main body 420 and the hydraulic motor main bodies 120 and 620 in the first and second axle drive devices 50 and 60 will be described later.

Further, in the present embodiment, the hydraulic pump unit 40 includes a first auxiliary pump main body 460 and a second auxiliary pump main body 470 that are operatively driven by the pump shaft 410 in addition to the above configuration. .
As shown in FIG. 3, the first auxiliary pump body 460 functions as a charge pump for supplying hydraulic oil to the HST.
The second auxiliary pump body 470 supplies hydraulic oil to the hydraulic steering mechanism 70.
The first auxiliary pump body 460 may be a trochoid pump, for example, and the second auxiliary pump body 470 may be a gear pump, for example.

As shown in FIG. 3, the working vehicle 1A has an external tank 90, and the first and second auxiliary pump bodies 460, 470 are configured to function as the oil source. Has been.
Note that reference numeral 435 in FIG. 3 is a drain pipe that fluidly connects the internal space of the pump case 430 to the external tank 90.

The first axle drive device 50 includes left and right first wheel motor devices 500L and 500R that drive the left and right first drive wheels 21L and 21R, respectively.
The left and right first wheel motor devices 500L and 500R have the same configuration, and each is mounted on the first frame 11 in a state where one of them is inverted 180 degrees with respect to the other.

As shown in FIG. 3, the first wheel motor device 500 includes a hydraulic motor main body 120 that forms an HST in cooperation with the hydraulic pump main body 420, and a reduction gear mechanism that reduces the rotational output of the hydraulic motor main body 120. 210, an output member 290 that outputs the rotational output decelerated by the reduction gear mechanism 210 toward the corresponding drive wheel 21, and a casing 300 that houses the hydraulic motor main body 120 and the reduction gear mechanism 210. Yes.
In the casing 300, an oil storage motor space 300 </ b> M that accommodates the hydraulic motor main body 120 is liquid-tightly partitioned from a gear space 300 </ b> G that accommodates the reduction gear mechanism 210.

  As shown in FIG. 3, the working vehicle 1 </ b> A including the left and right first wheel motor devices 500 </ b> L and 500 </ b> R having such a configuration has at least part of the oil discharged from the second auxiliary pump body 470 as the left and right. The first wheel motor devices 500L and 500R are configured to return to the suction side of the second auxiliary pump main body 470 through the motor spaces 300M, whereby the hydraulic motor main body 120 and the hydraulic pump main body 420 are used. The hydraulic motor main body 120 can be efficiently cooled while making it possible to use viscous oils suitable for the HST hydraulic oil formed and the lubricating oil of the reduction gear mechanism 210, respectively.

  That is, in the conventional wheel motor device configured to store the leaked oil from the hydraulic motor main body in the motor case that houses the hydraulic motor main body and return the stored oil that overflows from the motor case to the external tank. The motor case is always filled with relatively high-temperature HST hydraulic fluid that leaks from the hydraulic motor body, and the hydraulic motor body cannot be sufficiently cooled.

On the other hand, in the present embodiment, as described above, the pressure oil from the second auxiliary pump body 470 is used to store the motor space 300M in the left and right first wheel motor devices 500L and 500R. Oil is actively circulated.
Therefore, the cooling efficiency of the hydraulic motor main body 120 in the left and right first wheel motor devices 500L and 500R can be improved.

Preferably, a circulation line 700 that fluidly connects the discharge side of the second auxiliary pump body 470, the motor space 300M in the left and right first wheel motor devices 500L and 500R and the suction side of the second auxiliary pump body 470, An oil cooler 790 can be inserted.
By providing such a configuration, the cooling efficiency of the hydraulic motor main body 120 can be further improved.

In the present embodiment, as shown in FIG. 3, the working vehicle 1A has a suction in which one end is fluidly connected to the external tank 90 and the other end is fluidly connected to the suction side of the auxiliary pump body 470. A line 710, a discharge line 720 having one end fluidly connected to the discharge side of the auxiliary pump body 470 and the other end fluidly connected to the motor space 300M, and one end fluidly connected to the motor space 300M; The other end portion includes a return line 730 fluidly connected to the external tank 90, and the suction line 710, the discharge line 720, and the return line 730 form the circulation line 700.
A filter 715 is preferably inserted in the suction line 710.

In the present embodiment, as shown in FIG. 3, the discharge line 720 supplies the discharge oil from the second auxiliary pump body 470 to one of the pair of left and right first wheel motor devices 500L and 500R (this embodiment In the embodiment, the first discharge line 721 to be introduced into the motor space 300M of the right first wheel motor device 500R) and the motor space 300M in the one first wheel motor device 500R are connected to the other first wheel motor device 500L. And a second discharge line 722 that is fluidly connected to the motor space 300M.
The return line 730 is configured to fluidly connect the motor space 300M of the other first wheel motor device 500L to the external tank 90.

The first discharge line 721 is configured to supply return oil from the hydraulic steering mechanism 70 and surplus oil for the hydraulic operation mechanism 70 to the motor space 300M of the one wheel motor device 500R.
Specifically, the first discharge line 721 supplies the hydraulic steering mechanism supply line 721a for supplying hydraulic oil to the hydraulic steering mechanism hydraulic circuit 75 and the return oil from the hydraulic steering mechanism hydraulic circuit 75. A hydraulic steering mechanism discharge line 721b for supplying the motor space 300M of one wheel motor device 500R, and a hydraulic steering mechanism having one end fluidly connected to the supply line 721a and the other end fluidly connected to the discharge line 721b. And a hydraulic pressure setting line 721c in which a relief valve 725 is inserted.

As described above, the return oil from the hydraulic actuator and the excess oil for the hydraulic actuator are used while the second auxiliary pump body 470 is used as a hydraulic source of the hydraulic actuator (the hydraulic steering mechanism 70 in the present embodiment). By supplying the motor space 300M, the cooling efficiency of the hydraulic motor main body 120 can be improved without providing a dedicated auxiliary pump main body.
Of course, it is also possible to supply only one of the return oil from the hydraulic actuator or the surplus oil for the hydraulic actuator to the motor space 300M.

  More preferably, as shown in FIG. 3, the oil cooler 790 is inserted into the return line 730, one end is fluidly connected to the discharge line 720, and the other end is more oil flow than the oil cooler 790. A bypass line 740 fluidly connected to the return line 730 on the downstream side in the direction and a relief valve 745 inserted in the bypass line 740 to set a maximum hydraulic pressure of the discharge line 720 can be further provided.

  By providing such a configuration, for example, when the viscosity of the oil in the motor space 300M is increased at a low temperature or the like, and the hydraulic pressure in the motor space 300M is thereby increased, the oil cooler 790 is excessively large. It is possible to effectively prevent the hydraulic pressure from acting and to prevent the oil cooler from being damaged.

Here, a specific configuration of the first wheel motor device 500 will be described.
FIG. 4 is a longitudinal sectional view of the left first wheel motor device 500L.
As shown in FIG. 4, the first wheel motor device 500L decelerates the rotational output of the hydraulic motor unit 100 having the hydraulic motor body 120 fluidly connected to the hydraulic pump body 420 and the hydraulic motor body 120. The reduction gear unit 200 having the reduction gear mechanism 210 and the output member 290 that outputs the rotation output reduced by the reduction gear mechanism 200 toward the corresponding drive wheel 21L.

  As shown in FIGS. 3 and 4, the hydraulic motor unit 100 includes the hydraulic motor main body 120, a motor case 150 that forms the motor space 300M, and a motor shaft that supports the hydraulic motor main body 120 in a relatively non-rotatable manner. 110.

  As shown in FIG. 4, the hydraulic motor main body 120 includes a motor-side cylinder block 121 that is supported on the motor shaft 110 so as not to rotate relative to the motor shaft 110, and the motor-side cylinder block 121 cannot rotate relative to the axis and can move forward and backward in the axial direction. And a plurality of motor-side pistons 122 supported by the motor.

In the present embodiment, the hydraulic motor main body 120 is a fixed displacement type in which the suction / discharge amount is constant.
Therefore, in addition to the above-described configuration, the hydraulic motor unit 100 directly or indirectly engages with the free end portion of the motor-side piston 122 to define the forward / backward movement range of the motor-side piston 122. It has.

By the way, the motor-side piston generally includes a shoe-type piston whose free end is engaged with a corresponding swash plate via a shoe, and a swash plate whose free end corresponds to a thrust bearing or the like. There is a shoeless type piston that is engaged with the.
Although a shoeless type is advantageous from the viewpoint of manufacturing cost and the like, in the present embodiment, the motor side piston 122 is a shoe type as shown in FIG.

  That is, in the present embodiment, as shown in FIG. 3, the hydraulic motor main body 120 in the first axle driving device 50 and the hydraulic motor main body 620 in the second axle driving device 60 are combined with the single hydraulic pressure. The pump body 420 is fluidly connected in series.

In such a configuration, the hydraulic motor body located on the upstream side in the flow direction of the HST hydraulic oil is acted on by the hydraulic oil having a higher pressure than the hydraulic motor body located on the downstream side in the flow direction of the HST hydraulic oil.
In view of this point, the present embodiment employs a shoe-type motor-side piston 122 in the first axle drive device 50 that is located upstream in the flow direction of the HST hydraulic oil with reference to the time of forward movement of the vehicle. As described above, the second axle drive device 60 located on the downstream side in the flow direction of the HST hydraulic oil with respect to the time of forward movement of the vehicle employs a shoeless type motor-side piston 122 ′ (see FIG. 11 below), Accordingly, the HST transmission efficiency formed by the hydraulic pump main body 420, the hydraulic motor main body 120 in the first axle driving device 50, and the hydraulic motor main body 620 in the second axle driving device 60, while preventing an increase in manufacturing cost. We are trying to improve.

As in the present embodiment, when the working machine such as the mower device 80 is disposed outward in the vehicle front-rear direction from either the first drive wheel 21 or the second drive wheel 22 Preferably, the hydraulic motor main body of the first axle drive device 50 or the second axle drive device 60 on the side closer to the work implement is positioned upstream in the flow direction of the HST hydraulic fluid when the vehicle moves forward. Can be made.
By providing such a configuration, high-pressure hydraulic oil from the hydraulic pump main body 420 can be supplied to the hydraulic motor main body on which a large load caused by the working machine, which is a heavy object, acts.
In the present embodiment, as described above, the mower device 80 is disposed on the vehicle front side. Therefore, the hydraulic motor main body 120 in the first axle driving device 50 is positioned upstream in the flow direction of the HST hydraulic oil when the vehicle moves forward.

The motor case 150 constitutes the casing 300 together with a reduction gear case 250 described later.
Specifically, the motor case 150 is detachably connected to the motor case body 160 provided with an opening 165 through which the hydraulic motor body 120 can be inserted, and to the motor case body 160 so as to close the opening 165. And a motor side port block 170L.

  As shown in FIG. 4, the motor case body 160 has an inflow port 300M (in) for introducing oil into the motor space 300M formed by the motor case body 160 and the motor side port block 170L. At least two ports including an outflow port 300M (out) for allowing oil to flow out from the motor space 300M are provided.

  In the present embodiment, as shown in FIG. 3, the first discharge line 721 is fluidly connected to the inflow port 300M (in) in the right first wheel motor device 500R, and the right first wheel motor device 500R. The outflow port 300M (out) of the left first wheel motor device 500L and the inflow port 300M (in) of the left first wheel motor device 500L are fluidly connected by the second discharge line 722, and the outflow port 300M of the left first wheel motor device 500L. The return line 730 is fluidly connected to (out).

As shown in FIG. 3, the motor case 150 is a motor-side first hydraulic fluid passage 511 that is fluidly connected to the hydraulic motor main body 120, and at least one end portion is opened outwardly, and the motor-side hydraulic fluid is opened. A first hydraulic oil passage 511 that forms a port 511 (P), and a motor-side second hydraulic oil passage 512 that is fluidly connected to the hydraulic motor main body 120, at least one end being opened outwardly, A motor-side second hydraulic oil passage 512 that forms the hydraulic oil port 512 (P) is formed.
In the present embodiment, the motor side first and second hydraulic fluid passages 511 and 512 are formed in the motor side port block 170L.
As described above, the right first wheel motor device 500R not shown in FIG. 4 is inverted 180 degrees with respect to the left first wheel motor device 500L, and the motor-side port block 170R included therein and the The left and right parts are common to the motor side port block 170L.

FIG. 5 shows a longitudinal sectional view of the motor side port block 170.
FIG. 5A shows a longitudinal sectional view of the motor-side port block 170 (hereinafter referred to as the left motor-side port block 170L as appropriate) in the left first wheel motor device 500L along the line VV in FIG. FIG. 5 (b) shows a longitudinal sectional view of the motor side port block 170 (hereinafter referred to as right motor side port block 170R as appropriate) in the right first wheel motor device 500R.

As shown in FIG. 5, the motor side port block 170 includes
The first kidney port 501 opened on the motor sliding contact surface with which the hydraulic motor main body 120 is in sliding contact, and the motor sliding contact surface opened on the opposite side of the first kidney port 501 across the motor shaft 110. A second kidney port 502, the first motor side hydraulic fluid passage 511 fluidly connected to the first kidney port 501, and the motor side second hydraulic fluid passage 512 fluidly connected to the second kidney port 502. Is formed.

Preferably, at least one of the motor-side first hydraulic fluid passage 511 and the motor-side second hydraulic fluid passage 512 is opened at a plurality of locations on the outer surface of the motor-side port block 170.
Thus, by configuring at least one of the motor side first hydraulic fluid passage 511 and the motor side second hydraulic fluid passage 512 to have a plurality of hydraulic fluid ports, the motor side hydraulic fluid port and the The degree of design freedom can be improved with respect to the arrangement of the hydraulic oil piping that fluidly connects the hydraulic oil ports 441 (P) and 442 (P) on the pump side.

  That is, the positions of the hydraulic oil ports 441 (P) and 442 (P) on the pump side are determined by the installation posture of the pump case 430. Similarly, the position of the hydraulic oil port on the motor side is determined by the installation posture of the motor case 150. Therefore, when both the motor-side first hydraulic fluid passage 511 and the motor-side second hydraulic fluid passage 512 have only a single hydraulic fluid port, the motor-side first hydraulic fluid passage 511 is uniquely defined by the installation posture of the pump case 430. The hydraulic oil port on the pump side at a certain position and the hydraulic oil port on the motor side at a position uniquely defined by the installation posture of the motor case 150 must be fluidly connected by the hydraulic oil pipe.

On the other hand, as described above, if at least one of the motor-side first hydraulic fluid passage 511 and the motor-side second hydraulic fluid passage 512 has a plurality of the hydraulic fluid ports, the pressure balance is lost. Therefore, it is possible to improve the degree of design freedom regarding the installation of the hydraulic oil pipe.
More preferably, the plurality of hydraulic oil ports on the motor side may be configured to face different directions with respect to each other.

  Further, as in the working vehicle 1A, a single hydraulic pump main body 420 allows the hydraulic motor main body 120 (hereinafter referred to as the left first hydraulic motor main body 120L) and the right side first wheel motor device 500L in the left first wheel motor device 500L. When both the hydraulic motor main body 120 (hereinafter referred to as the right first hydraulic motor main body 120R) in the one-wheel motor device 500R are driven hydraulically and differentially (see FIG. 3), the first motor side By configuring at least one of the hydraulic fluid passage 511 and the second hydraulic fluid passage 512 on the motor side to have a plurality of the hydraulic fluid ports, it is not necessary to provide the hydraulic fluid piping with a branch structure such as a T-shaped joint, The single hydraulic pump main body 420 is transformed into a pair of the hydraulic motor main bodies 120L and 120R, and the pressure balance is lost. Can be fluidly connected without a pipe work efficiency can be improved.

In the present embodiment, as shown in FIG. 5, the motor-side first hydraulic fluid passage 511 has a plurality of hydraulic fluid ports, and the motor-side second hydraulic fluid passage 512 is a single hydraulic fluid. Has a port.
Specifically, the motor-side first hydraulic fluid passage 511 has a first hydraulic fluid port 511 (P1) that faces a first direction D1, which is one of the directions orthogonal to the motor shaft 110, and the motor shaft 110. And a second hydraulic oil port 511 (P2) that faces a second direction D2 that is perpendicular to the first direction D1 and is also perpendicular to the first direction D1.
On the other hand, the motor-side second hydraulic fluid passage 512 has only a first hydraulic fluid port 512 (P1) that faces the first direction D1.

  Here, in the case where the pump side first hydraulic fluid passage 441 is on the high pressure side when moving forward and the pump side second hydraulic fluid passage 442 is on the low pressure side when traveling forward, the hydraulic pump main body 420 and the left side are exemplified. A pipe connection structure between the first hydraulic motor main body 120L and the right first hydraulic motor main body 120R will be described.

  As shown in FIGS. 1 to 3 and 5, the working vehicle 1 </ b> A has a pump-side advance high-pressure pipe whose one end is fluidly connected to the hydraulic oil port 441 (P) of the pump-side first hydraulic oil passage 441. 311F, a pump-side reverse pressure high-pressure pipe 311R whose one end is fluidly connected to the hydraulic oil port 442 (P) of the pump-side second hydraulic oil passage 442, and one end of the flexible pipe 315 (see FIG. 2). Through the second hydraulic oil port 511 (P2 of the motor side first hydraulic fluid passage 511 in the left motor side port block 170L). ) Fluidly connected to the first axle-side forward high-pressure pipe 321F and one end of the fluid to the first hydraulic oil port 511 (P1) of the motor-side first hydraulic oil passage 511 in the left motor-side port block 170L. Connected A first axle-side advance high-pressure connection pipe 322F, the other end of which is fluidly connected to the first hydraulic oil port 512 (P1) of the motor-side second hydraulic oil passage 512 in the right motor-side port block 170R; One end is fluidly connected to the first hydraulic oil port 512 (P1) of the motor-side second hydraulic oil passage 512 in the left motor-side port block 170L, and the other end is the motor in the right motor-side port block 170R. The first axle-side reverse high-pressure connection pipe 322R fluidly connected to the second hydraulic oil port 511 (P2) of the first hydraulic oil passage 511, and one end of the motor-side first in the right motor-side port block 170R. One hydraulic oil passage 511 is fluidly connected to the first hydraulic oil port 511 (P1) and the other end is directly or indirectly fluidly connected to the pump-side reverse pressure high-pressure pipe 311R. And a first axle-side backward when the high-pressure pipe 321R is.

  That is, in the left motor side port block 170L, the motor side first hydraulic fluid passage 511 is a high pressure side hydraulic fluid passage at the time of forward movement, whereas in the right motor side port block 170R, the motor side second hydraulic fluid passage is provided. The path 512 becomes a high-pressure side hydraulic oil path when moving forward.

  In the present embodiment, as described above, the single hydraulic pump body 420 causes the hydraulic motor body 120 of the first axle drive device 50 (that is, the left first hydraulic motor body 120L and the right side first hydraulic motor body 120L). 1 hydraulic motor main body 120R) and the hydraulic motor main body 620 of the second axle driving device 60 are hydraulically driven. Accordingly, the hydraulic motor main body 620 in the second axle driving device 60 is interposed between the other end of the first axle-side reverse high-pressure pipe 321R and the other end of the pump-side reverse high-pressure pipe 311R. Has been.

Preferably, the bypass oil passage 520 communicating with the motor side first hydraulic fluid passage 511 and the motor side second hydraulic fluid passage 512 and the bypass oil passage 520 are selectively communicated with the motor case 150 or An externally operable bypass valve 530 that can be shut off can be provided.
In the present embodiment, as shown in FIGS. 3 and 5, the bypass oil passage 520 and the bypass valve 530 are provided in the motor-side port block 170.

  Thus, by providing the motor case 150 with the bypass oil passage 520 and the bypass valve 530, when the vehicle is forcibly pulled when the HST or the drive source 30 fails, the hydraulic motor The hydraulic oil discharged from the main body 120 can be prevented from acting so as to hydraulically drive the hydraulic pump main body 420.

Furthermore, according to the said structure, the tractive force required when forcibly towing a vehicle can be reduced as much as possible.
That is, in a conventional work vehicle including a hydraulic pump unit and a wheel motor device that are spaced apart from each other, the hydraulic pump unit having a hydraulic pump body that forms an HST in cooperation with the hydraulic motor body in the wheel motor device. In addition, a bypass oil passage and a bypass valve are provided.

This conventional configuration can also prevent a hydraulic pressure difference from occurring between a pair of hydraulic oil lines that fluidly connect the hydraulic pump body and the hydraulic motor body when the vehicle is forcibly pulled.
However, in the conventional configuration, the hydraulic oil sucked and discharged by the hydraulic motor main body with forced traction of the vehicle is the motor-side first hydraulic oil path, the first hydraulic oil pipe, and the pump-side first hydraulic oil path. Circulates through the bypass oil path on the pump side, the second hydraulic oil path on the pump side, the second hydraulic oil pipe, and the second hydraulic oil path on the motor side.
In other words, in the conventional configuration, the hydraulic oil sucked / discharged by the hydraulic motor main body as the vehicle is forcibly pulled is almost the whole of a pair of hydraulic oil lines that fluidly connect the hydraulic motor main body and the hydraulic pump main body. The force for circulating the hydraulic oil becomes a power loss with respect to the vehicle traction force.

On the other hand, in the present embodiment, as described above, the bypass oil passage 520 and the bypass valve 530 are provided in the motor case 150.
Accordingly, the hydraulic oil sucked / discharged by the hydraulic motor main body 120 during the forced traction of the vehicle passes through the motor-side first hydraulic oil passage 511, the bypass oil passage 520, and the motor-side second hydraulic oil passage 512. It is circulated, thereby reducing the traction power loss due to the circulation of the hydraulic oil.

  In the present embodiment, as shown in FIG. 5, the motor-side first hydraulic oil passage 511 branches in a direction perpendicular to the main oil passage 511a along the first direction D1 and the main oil passage 511a. And a branched oil passage 511b. The main oil passage 511a is fluidly connected to the first kidney port 501 and one end thereof opens to the outer surface to form the first hydraulic oil port 511 (P1). One end of the branch oil passage 511b opens to the outer surface to form the second hydraulic oil port 511 (P2).

  The motor-side second hydraulic fluid path 512 has a main oil path 512a that is substantially parallel to the main oil path 511a of the motor-side first hydraulic fluid path 511 with the motor shaft 110 interposed therebetween. The main oil passage 512a is fluidly connected to the second kidney port 502, and one end thereof opens to the outer surface to form the first hydraulic oil port 512 (P1).

The bypass oil passage 520 includes a main oil passage 511a of the motor-side first hydraulic oil passage 511 and a main oil passage of the motor-side second hydraulic oil passage 512 in a state where the first end 520a is opened on the outer surface. It is formed so as to cross both of 512a.
The bypass valve 530 is inserted from the first end 520 a of the bypass oil passage 520.

Preferably, as shown in FIG. 5, the bypass oil passage 520 has the motor-side first and second hydraulic oil passages 511 and 512 on the opposite side of the branch oil passage 511 b with respect to the motor shaft 110. The main oil passages 511a and 512a are formed so as to be substantially orthogonal.
According to such a configuration, the branch oil passage 511b and the bypass valve 520 can be formed while preventing the motor-side port block 170 from being enlarged as much as possible.

Preferably, as shown in FIG. 6, the second end portion 520b of the bypass oil passage 520 can be opened on the side surface opposite to the side surface where the first end portion 510a is opened.
According to such a configuration, it is possible to facilitate access to the bypass valve 530 in both the pair of left and right first wheel motor devices 500L and 500R.

That is, in the form shown in FIG. 5, the bypass valve 530 in the left first wheel motor device 500 </ b> L has a base end portion (operation end portion) located on a side surface of the motor side port block 170 on the vehicle front side. On the other hand, the bypass valve 530 in the right first wheel motor device 500R has a proximal end located on the side surface of the motor side port block 170 on the vehicle rear side.
As in the present embodiment, when the pair of left and right wheel motor devices 500L and 500R drives the first drive wheel 21 located on the front side of the vehicle, the bypass valve 530 in the left first wheel motor device 500L is connected to the bypass valve 530. Although it can be easily accessed from the front side of the vehicle, the bypass valve 530 in the right first wheel motor device 500R cannot be accessed unless it goes down below the vehicle frame.

On the other hand, in the form shown in FIG. 6, the base end of the bypass valve 530 can be positioned on the vehicle front side in both of the pair of left and right first wheel motor devices 500L and 500R. Access to both bypass valves 530 can be facilitated.
Of the openings at both ends of the bypass oil passage 520, the opening on the side where the bypass oil passage 530 is not inserted is closed by a plug 525.
In the form shown in FIG. 6, in the left first wheel motor device 500 </ b> L, the bypass oil passage 530 is inserted from the first end 520 a of the bypass oil passage 520 and the second end of the bypass oil passage 520. 520 b is closed by a plug 525.
On the other hand, in the right first wheel motor device 500R, the bypass valve 530 is inserted from the second end 520b of the bypass oil passage 520 and the first end 520a of the bypass oil passage 520 is closed by a plug 525. ing.

FIG. 7 shows a longitudinal sectional view of a motor-side port block 170 ′ having a different form.
7A and 7B show the motor-side port block 170 ′ (hereinafter referred to as the left motor-side port block 170′L as appropriate) and the right-side first wheel motor device 500L in the left first wheel motor device 500L, respectively. The motor side port block 170 ′ (hereinafter, referred to as right motor side port block 170′R as appropriate) in the one-wheel motor device 500R is shown.

  The motor side port block 170 ′ includes first and second kidney ports 501 and 502, and motor side first and second hydraulic fluid passages 511 that are fluidly connected to the first and second kidney ports 501 and 502, respectively. ', 512', the bypass oil passage 520, and the bypass valve 530.

The motor side first hydraulic fluid passage 511 ′ is in addition to the first hydraulic fluid port 511 (P1) facing the first direction D1 and the second hydraulic fluid port 511 (P2) facing the second direction D2. The third hydraulic oil port 511 (P3) faces the third direction D3, which is the opposite direction to the first direction D1.
Specifically, the motor-side first hydraulic fluid passage 511 ′ has one end opened toward the first direction D1 to form the first hydraulic fluid port 511 (P1), and the other end is the third. A main oil passage 511a ′ along the first and third directions D1, D3 and the main oil passage 511a ′ so as to open toward the direction D3 to form the third hydraulic oil port 511 (P3). And a branch oil passage 511b that branches in a direction orthogonal to the front end and opens in the second direction to form the second hydraulic oil port 511 (P2).

The motor-side second hydraulic fluid passage 512 ′ faces the fourth direction D4, which is the opposite direction to the second direction D2, in addition to the first hydraulic fluid port 512 (P1) facing the first direction D1. A second hydraulic oil port 512 (P2) and a third hydraulic oil port 512 (P3) facing the third direction D3 are provided.
Specifically, the motor-side second hydraulic oil passage 512 ′ has one end opened in the first direction D1 to form the first hydraulic oil port 512 (P1) and the other end is the third. A main oil passage 512a ′ along the first and third directions D1 and D3 and the main oil passage 512a ′ so as to open toward the direction D3 to form the third hydraulic oil port 512 (P3). And a branch oil passage 512b that branches off in a direction perpendicular to each other and that has a leading end opened in the second direction to form the second hydraulic oil port 512 (P2).

  The bypass oil passage 520 intersects the motor-side first and second hydraulic oil passages 511 ′ and 512 ′ with the first end portion 512 a opened in the fourth direction D <b> 4.

The motor-side port block 170 ′ can be connected to the motor case body 160 at a first position around the axis of the motor shaft 110 and a second position displaced from the first position around the axis of the motor shaft 110. It is said that.
In the motor side port block 170 ′ shown in FIG. 7, four mounting holes 179 for the motor case main body 160 are provided with the same radius with respect to the axis of the motor shaft 110 and at intervals of 90 degrees around the axis. ing.
Therefore, the motor-side port block 170 ′ can take one connection posture and the other three connection postures displaced from the one connection posture around the axis of the motor shaft 110 by 90 degrees. ing.
In the form shown in FIG. 7, the right motor side port block 170′R (see FIG. 7 (b)) is different from the left motor side port block 170′L (see FIG. 7 (a)). The motor case body 160 is connected to the motor case body 160 while being displaced 180 degrees around the axis of the motor shaft 110.

  Even in the motor-side port block shown in FIG. 7, an external piping structure that fluidly connects the single hydraulic pump main body 420, the left first hydraulic motor main body 120 </ b> L, and the right first hydraulic motor main body 120 </ b> R. In this way, it is possible to facilitate access to the bypass valve 530 in the pair of left and right first wheel motor devices 500L and 500R.

  Here, regarding the pipe connection structure when the motor-side port block 170 ′ is used, the pump-side first hydraulic fluid passage 441 becomes a high-pressure side when moving forward, and the pump-side second hydraulic fluid passage 442 is moved backward. The case where it is on the high pressure side will be described as an example.

In the second hydraulic oil port 511 (P2) of the motor-side first hydraulic fluid passage 511 ′ in the left motor-side port block 170′L, the other end of the first axle-side forward high-pressure pipe 321F is fluid. Connected. The first hydraulic oil port 511 (P1) of the motor-side first hydraulic oil passage 511 in the left motor-side port block 170′L is connected to the left motor via the first axle-side advance high-pressure connection pipe 322F. The third operating port 511 (P3 of the motor-side first hydraulic fluid passage 511 ′ in the right motor-side port block 170′R, which is displaced 180 degrees around the motor shaft 110 with respect to the side port block 170′L. ) Is fluidly connected.
The third hydraulic oil port 511 (P3) of the motor first hydraulic fluid passage 511 ′ in the left motor side port block 170′L, and the motor side first in the right motor side port block 170′R. The first and second hydraulic oil ports 511 (P1) and 511 (P2) of the first hydraulic oil passage 511 ′ are closed by a plug 515.

The first hydraulic oil port 512 (P1) of the motor-side second hydraulic oil passage 512 ′ in the left motor-side port block 170′L is connected to the right via the first axle side reverse travel high-pressure connection pipe 322R. The motor-side port block 170′R is fluidly connected to the second hydraulic oil port 512 (P2) of the motor-side second hydraulic oil passage 512 ′. The first axle-side reverse travel high-pressure pipe 321R is connected to the third hydraulic oil port 512 (P3) of the motor-side second hydraulic oil passage 512 ′ in the right motor-side port block 170′R. Yes.
The second and third hydraulic oil ports 512 (P2) and 512 (P3) of the second motor-side hydraulic fluid passage 512 ′ in the left motor-side port block 170′L, and the right motor-side port block. The first hydraulic oil port 512 (P1) of the motor-side second hydraulic oil passage 512 ′ at 170′R is closed by a plug 515.

Instead of the motor-side port blocks 170 and 170 ′ shown in FIGS. 5 to 7, a motor-side port block 170 ″ shown in FIG. 8 may be employed.
Specifically, the motor-side port blocks 170 and 170 ′ shown in FIGS. 5 to 7 block between the motor-side first hydraulic fluid passage 511 and the motor-side second hydraulic fluid passage 512 based on an external operation. The HST operable state and the HST non-operating state in which the hydraulic fluid passages 511 and 512 communicate with each other while maintaining the closed circuit of the HST hydraulic fluid line are configured to be switchable. The side port block 170 '' is configured to be switchable between the HST operable state and the HST non-operating state for releasing the closed circuit of the HST hydraulic oil line based on an external operation.
FIG. 8A shows the motor-side port block 170 ″ (hereinafter, referred to as the left motor-side port block 170 ″ L as appropriate) in the left first wheel motor device 500L, and FIG. The motor side port block 170 ″ in the right first wheel motor device 500R (hereinafter, referred to as right motor side port block 170 ″ R as appropriate) is shown.

  Specifically, as shown in FIG. 8, the motor side port block 170 ″ includes the first and second kidney ports 501 and 502, the motor side first and second hydraulic oil passages 511 and 512, The bypass oil passage 520 communicating between the motor-side first hydraulic fluid passage 511 and the motor-side second hydraulic fluid passage 512, the rotary valve 540 inserted in the bypass oil passage 520, and one end portion thereof A drain oil passage 550 opened to the motor space 300M is provided.

The rotary valve 540 is configured to rotate about an axis based on an external operation, and can take a blocking position for blocking the bypass oil passage 520 and a communication position for communicating the bypass oil passage 520. It has become.
Further, the rotary valve 540 shuts off the drain oil passage 550 with respect to the bypass oil passage 520 when positioned at the shut-off position, and the drain oil passage 550 when positioned at the communication position. The bypass oil passage 520 is configured to communicate with the bypass oil passage 520.

  With such a configuration, even if the hydraulic motor main body 120 rotates as the vehicle is forcibly pulled, the hydraulic pressure discharged from the hydraulic motor main body 120 can be prevented from being transmitted to the hydraulic pump main body 420. At the same time, when air is mixed into a pair of hydraulic oil lines that fluidly connect the hydraulic motor main body 120 and the hydraulic pump main body 420, the air can be extracted as quickly as possible.

In the present embodiment, as described above, the pressure oil from the single hydraulic pump main body 420 is distributed to the left first hydraulic motor main body 120L and the right first hydraulic motor main body 120R.
In such a configuration, when either one of the left and right first drive wheels 21L, 21R enters a groove or a swamp, the pressure oil from the hydraulic pump body 420 has a low load. It becomes easy to flow to the hydraulic motor main body 120 corresponding to the first driving wheel 21, and as a result, it is difficult to supply pressure oil to the hydraulic motor main body 120 that drives the other first driving wheel 21.
Considering this point, preferably, the first wheel motor device 500 may be provided with a hydraulic differential lock mechanism 560.

FIG. 9 is a hydraulic circuit diagram in the vicinity of the first axle drive device 50 provided with the hydraulic differential lock mechanism 560.
In the embodiment shown in FIG. 9, the hydraulic differential lock mechanism 560 includes a forward switching valve 565F and a reverse switching valve 565R.
The forward-time switching valve 565F is inserted into a motor-side hydraulic fluid passage that has a high pressure during forward travel and is provided with a plurality of hydraulic fluid ports.
The reverse switching valve 565R is inserted into a motor-side hydraulic oil passage that is high in reverse and has a plurality of hydraulic oil ports.
Preferably, the switching valves 565F and 565R may be mounted on or housed on the outer surface of the motor-side port block 170 of the first wheel motor device 500.

The switching valves 565F and 565R are a hydraulic differential state in which the pressure oil from the hydraulic pump 420 is directly divided into the left first hydraulic pump main body 120L and the right first hydraulic motor main body 120R, and the pressure oil The hydraulic differential lock state in which the left first hydraulic pump main body 120L and the right first hydraulic motor main body 120R are diverted at a predetermined diversion ratio to each other through a restrictor can be switched.
Depending on the specifications, either the forward switching valve 565F or the reverse switching valve 565R can be deleted.

Next, the reduction gear unit 200 will be described.
As shown in FIGS. 3 and 4, the reduction gear unit is detachably connected to the motor case 150 so as to form the reduction gear mechanism 210 and a gear space 300 </ b> G that accommodates the reduction gear mechanism 210. A gear case 250 is provided.

  In the present embodiment, the reduction gear mechanism 210 has first and second planetary gear mechanisms 220a and 220b arranged in series with respect to each other.

Specifically, in the motor case 150, a through hole 155 (in the present embodiment, an end on the outer side in the vehicle width direction) that allows the motor shaft 110 to enter the gear space 300G is provided. 4) is formed. The reduction gear mechanism 210 is configured to reduce the rotational power from the one end of the motor shaft 110.
As shown in FIG. 4, an oil seal member 116 is disposed in the through hole 155 in addition to the bearing member 115 that supports the motor shaft 110 so as to be rotatable about its axis, and the oil seal member 116, the motor space 300M and the gear space 300G are partitioned in a liquid-tight manner.

Specifically, the first planetary gear mechanism 220a is configured to revolve around a first sun gear 221a supported on the one end portion of the motor shaft 110 so as not to rotate relative to the first sun gear 221a. A first planetary gear 224a meshing with the sun gear 221a; a first carrier 222a that supports the first planetary gear 224a in a relatively rotatable manner and revolves around the first sun gear 221a according to the revolution of the first planetary gear 224a; And a first internal gear 223a meshing with the first planetary gear 224a.
The second planetary gear mechanism 220b includes a second sun gear 221b that is operatively connected to the first carrier 222a, and a second planetary gear that meshes with the second sun gear 221b so as to revolve around the second sun gear 221b. 224b, a first carrier 222b that supports the second planetary gear 224b so as to be relatively rotatable and revolves around the second sun gear 221b in accordance with the revolution of the second planetary gear 224b, and meshes with the second planetary gear 224b. Second internal gear 223b.

The gear case 250 forms the casing 300 in cooperation with the motor case 150.
In the present embodiment, the gear case 250 includes a first gear case 260 coupled to the motor case 150 and a second gear case 270 coupled to the motor case 150 with the first gear case 260 interposed therebetween. Have.

  The first gear case 260 has a hollow shape in which both an inner side in the vehicle width direction in contact with the motor case 150 and an outer side in the vehicle width direction opposite to the motor case 150 are opened, The first and second internal gears 223a and 223b are integrally formed on the inner peripheral surface.

The second gear case 270 is a hollow in which the inner side in the vehicle width direction contacting the first gear case 260 is opened and the outer side in the vehicle width direction opposite to the first gear case 260 is closed by an end wall. It is made into a shape.
A through hole 275 through which the output member 290 is inserted is provided in the end wall of the second gear case 270.

The output member 290 includes a flange portion 291 coupled to the second carrier 222b so as to rotate about the axis along with the rotation of the second carrier 222b around the second sun gear 221b, and the flange portion 291 from the vehicle. And an output shaft portion 292 extending outward in the width direction.
In the present embodiment, the output member 290 includes a first bearing member 295 disposed between an inner peripheral surface of the second gear case 270 and an outer peripheral surface of the flange portion 291, and the second gear case 270. Are supported at two points by a second bearing member 296 disposed between the inner peripheral surface of the through-hole 275 and the outer peripheral surface of the output shaft portion 292 formed in the end wall of It can rotate stably around the axis.

  In this way, the rotational power of the hydraulic motor main body 120 is decelerated by the reduction gear mechanism 210, and the reduced rotational power is transmitted to the corresponding drive wheels 21, whereby the hydraulic motor main body 120 has a low torque and high torque. A rotary hydraulic motor main body can be used. Therefore, the hydraulic motor main body 120 can be reduced in size, the amount of hydraulic oil leakage from the hydraulic motor main body 120 can be reduced, and the transmission efficiency of HST can be improved.

Further, in the present embodiment, the first wheel motor device 500 is provided with a brake unit 310.
The brake unit 310 is configured to be able to apply a braking force to the motor shaft 110 before being decelerated by the reduction gear mechanism 210.

Specifically, as shown in FIG. 4, the motor shaft 110 has the other end opposite to the one end on the outer side in the vehicle width direction protruding from the motor case 150 toward the inner side in the vehicle width direction. The brake rotor of the brake unit 310 is attached to the other end.
The brake unit 310 is connected to the motor case 150 so as to selectively apply a braking force to the other end of the motor shaft 110 based on an external operation.
In the present embodiment, the brake unit 310 is an inward-expanding drum brake built in a brake case, but instead, a band in which a drum-shaped brake rotor is exposed to the outside. A brake can be used, or a disc brake can be used.

Next, the second axle drive device 60 will be described.
The second axle drive device 60 is configured to hydraulically drive the pair of left and right second drive wheels 22L, 22R using the pressure oil from the hydraulic pump body 420.
In the present embodiment, as described above, the first axle drive device 50 and the second axle drive device 60 are fluidly connected in series to the hydraulic pump body 420. Therefore, the second axle drive device 60 is driven by the return oil from the first axle drive device 50.

The second axle drive device 60 can take various forms.
10 (a) to 10 (c) show hydraulic circuit diagrams of the second axle drive device 60 in various forms.
In FIG. 10, the same members as those described above are denoted by the same reference numerals.

The second axle drive device 60A shown in FIG. 10 (a) is configured to differentially drive the pair of left and right second drive wheels 22L and 22R via a mechanical differential gear mechanism 640A.
Specifically, the second axle driving device 60A rotates a single second hydraulic motor main body 620 that is fluidly connected directly or indirectly to the hydraulic pump main body 420 and the second hydraulic motor main body 620. An output motor shaft 610, a reduction gear mechanism 630A that reduces the rotation of the motor shaft 610, and a mechanical type that differentially transmits the rotation reduced by the reduction gear mechanism 630A to the pair of left and right second drive wheels 22L and 22R. A differential gear mechanism 640A, and a hydraulic motor main body 620, the motor shaft 610, the reduction gear mechanism 630A, and an axle case 650A that accommodates the differential gear mechanism 640A are provided.

As shown in FIG. 10A, the axle case 650A includes a pair of second motor side first and second hydraulic fluid passages 661 and 662 fluidly connected to the second hydraulic motor main body 620, A pair of second motor side first and second hydraulic fluid passages 661 and 662 is provided, one of which becomes high pressure when moving forward and the other becomes high pressure when moving backward.
The second motor-side hydraulic fluid passage 661F is fluidly connected to the second motor-side hydraulic fluid passage (for example, the second motor-side first hydraulic fluid passage 661) that is high in forward travel, and is high in reverse travel. A second axle-side reverse high-pressure pipe 331R is fluidly connected to the second motor-side hydraulic fluid passage (for example, the second motor-side second hydraulic fluid passage 662).

As described above, in the present embodiment, the first and second axle drive devices 50 and 60 are fluidly connected in series to the hydraulic motor body 420.
Accordingly, the second axle-side forward high-pressure pipe 331F is fluidly connected to the first axle-side reverse high-pressure pipe 321R, and the second axle-side reverse high-pressure pipe 331R is connected to the pump-side reverse high-pressure pipe 331R. It is fluidly connected to 311R.
A flexible pipe 335 (see FIG. 2) is interposed between the second axle side forward high pressure pipe 331F and the first axle side reverse high pressure pipe 321R.

  Further, as shown in FIG. 10 (a), the second axle drive device 60A includes the rotary valve 540 interposed between the second motor side first and second hydraulic fluid passages 611 and 612. A drain pipe 750 for fluidly connecting the internal space of the axle case 650A to the oil tank 90 is provided.

The second axle drive device 60B shown in FIG. 10B includes a pair of left and right second wheel motor devices 600L and 600R that drive the pair of left and right second drive wheels 22L and 22R, respectively.
The pair of left and right second wheel motor devices 600L and 600R have the same configuration.
The second wheel motor device 600 has substantially the same configuration as the first wheel motor device 500 except that the hydraulic motor unit 100 is replaced with a hydraulic motor unit 100B.
That is, the second wheel motor device 600 includes a hydraulic motor unit 100B, the reduction gear unit 200, and the output member 290.

The hydraulic motor unit 100B in the left second wheel motor device 600L is fluidly connected to the second hydraulic motor main body 620 (hereinafter referred to as the left second hydraulic motor main body 620L) and the left second hydraulic motor main body 620L. And a pair of second motor side first and second hydraulic fluid passages 661 and 662.
The second motor side first hydraulic fluid passage 661 has a first hydraulic fluid port 661 (P1), and the second motor side second hydraulic fluid passage 662 has a first hydraulic fluid port 662 (P1). Yes.

The hydraulic motor unit 100B in the right second wheel motor device 600R is fluidly connected to the second hydraulic motor main body 620 (hereinafter referred to as the right second hydraulic motor main body 620R) and the right second hydraulic motor main body 620R. And a pair of second motor side first and second hydraulic fluid passages 661 and 662.
The second motor side first hydraulic fluid passage 661 has a first hydraulic fluid port 661 (P1), and the second motor side second hydraulic fluid passage 662 has a first hydraulic fluid port 662 (P1). Yes.

The left second wheel motor device 600L has a high pressure side second motor side hydraulic fluid passage (for example, the second motor side first hydraulic fluid passage 661) and the right second wheel motor device 600R has a forward high pressure side. The second motor side hydraulic fluid passage (for example, the second motor side first hydraulic fluid passage 661) is fluidly connected via the second axle side forward advance high pressure connection pipe 332F.
Similarly, in the left second wheel motor device 600L, the second motor side hydraulic fluid passage (for example, the second motor side second hydraulic fluid passage 662) on the high pressure side during reverse travel and the reverse motion in the right second wheel motor device 600R. The high pressure side second motor side hydraulic fluid passage (for example, the second motor side second hydraulic fluid passage 662) is fluidly connected via the second axle side reverse travel high pressure connection pipe 332R.

Further, at least one of the pair of left and right second wheel motor devices 600L and 600R (the right second wheel motor device 600R in FIG. 10B) is connected to the second motor side hydraulic fluid passage 611 on the high pressure side during forward travel. A fluid pressure-connected forward high-pressure side second hydraulic oil port 661 (P2) is provided.
The second axle side forward high pressure pipe 331F is fluidly connected to the forward high pressure side second hydraulic oil port 661 (P2).

Further, at least one of the pair of left and right second wheel motor devices 600L and 600R (the second wheel motor device 600L on the left side in FIG. 10B) is connected to the second motor side hydraulic fluid passage 662 on the high pressure side during reverse travel. A reverse hydraulic pressure second hydraulic oil port 662 (P2) connected to the fluid is provided. As a result, like the first wheel motor devices 500L and 500R, both the right second hydraulic motor main body 620R and the left first hydraulic motor main body 620L are hydraulic and differential by the single hydraulic pump main body 420. Driven.
The second axle side reverse pressure high pressure pipe 331R is fluidly connected to the reverse pressure high pressure side second hydraulic oil port 662 (P2).
In addition, the code | symbol 755 in FIG.10 (b) is connection piping which fluidly connects the motor space 600M in the said left 2nd wheel motor apparatus 600L and the motor space 600M in the said right 2nd wheel motor apparatus 600R.

In the second axle drive device 60C shown in FIG. 10 (c), the left second hydraulic motor main body 620L and the right second hydraulic motor main body 620R are accommodated integrally.
Specifically, the second axle drive device 60C includes the left second hydraulic motor main body 620L and the right second hydraulic pressure that are fluidly connected to form a closed circuit via a pair of second motor side hydraulic oil lines 340. A motor main body 620R and a motor case 650C for housing the pair of second hydraulic motor main bodies 620L and 620R are provided.

Of the pair of second motor side hydraulic oil lines 340, the second axle side forward hydraulic pressure line 331F is fluidly connected to a second motor side hydraulic oil line that has a high pressure during forward movement.
Of the pair of second motor side hydraulic oil lines 340, the second axle side reverse pressure high pressure pipe 331 </ b> R is fluidly connected to a second motor side hydraulic oil line that has a high pressure during reverse travel.

The second axle driving device 60C is further provided with a pair of reduction gear units 660 on both sides of the motor case 650C in the vehicle width direction.
The reduction gear unit 660 includes a king pin shaft 661 extending in the vertical direction, and a first bevel gear reduction gear 662 provided on the upper end side of the king pin shaft 661 so as not to be relatively rotatable. The corresponding second hydraulic motor A first bevel gear-type reduction gear 662 operatively connected to the main body 620 and a second bevel gear-type reduction gear 663 provided on the lower end side of the kingpin shaft 661, which operate on the corresponding second drive wheel 22. It has a second bevel gear type reduction gear 663 to be connected, and supports the corresponding second drive wheel 22 around the kingpin shaft 661 so as to be steerable.

Here, the second hydraulic motor main body 620 will be described by taking the second axle drive device 60B shown in FIG. 10 (b) as an example.
FIG. 11 is a longitudinal sectional view of the left second wheel motor device 600L.
In the figure, the same members as those of the first wheel motor device 500 are denoted by the same reference numerals, and the description thereof is omitted.

  The hydraulic motor unit 100B in the second wheel motor device 600 includes the second hydraulic motor main body 620, a motor case 150B, and the motor shaft 110, as shown in FIG.

  As shown in FIG. 11, the second hydraulic motor main body 620 includes the motor-side cylinder block 121 that is supported by the motor shaft 110 so as not to rotate relative to the motor-side shaft 110, and the motor-side cylinder block 121 is relatively non-rotatable around the axis and is And a plurality of motor-side pistons 122 ′ supported so as to be capable of moving forward and backward.

As shown in FIG. 11, the motor side piston 122 ′ of the second hydraulic motor main body 620 is a shoeless type in which a free end is engaged with a corresponding swash plate 130B via a thrust bearing 125 ′. As a result, the cost is reduced.
That is, as described above, in the present embodiment, the first axle drive device 50 is located upstream in the HST hydraulic fluid flow direction and the second axle drive device 60 It is located downstream of the HST hydraulic fluid flow direction.
Therefore, although the high pressure hydraulic oil acts on the hydraulic motor main body 120 in the first axle driving device 50, the high pressure hydraulic oil does not act on the second hydraulic motor main body 620.
Focusing on this point, in the present embodiment, the hydraulic motor main body 120 in the first axle drive device 50 is a shoe type, and the second hydraulic motor main body 620 is a shoeless type.

In the present embodiment, the suction / discharge amount of the second hydraulic motor main body 620 is configured to be artificially and arbitrarily changed, whereby the first drive wheels 21L and 21R are The drive rotation speed of the second drive wheels 22L and 22R can be relatively increased or decreased.
By providing such a configuration, it is possible to appropriately adjust the rotation speeds of the first and second drive wheels during straight traveling to improve running stability and reduce tire abnormal wear. Furthermore, the speed of the second drive wheels 22L and 22R relative to the first drive wheels 21L and 21R can be changed at any time according to the operation amount of the steering member 5, and the second when the vehicle turns. It is possible to compensate for a turning radius difference that may occur between the drive wheel 22 and the first drive wheel 21.
Therefore, the hydraulic motor unit 100B is a movable swash plate 130B that directly or indirectly engages with the free end portion of the motor-side piston 122 ′, in addition to the above-described configuration. A movable swash plate 130B for changing the advancing / retreating operation range of the side piston 122 ′ and a support shaft 131B rotated around an axis line based on an external operation are provided.
In the present embodiment, the movable swash plate 130B is a cradle type, but may be a trunnion type.

FIG. 12 shows a detailed view of the vicinity of the support shaft 131B and the movable swash plate 130B.
The motor case 150B includes a motor case main body 160B and the motor side port block 170.
The motor case main body 160B has an opening (not shown) on the side. As shown in FIG. 12, a side cover 161B that closes the opening is detachably connected to the motor case body 160B.
The support shaft 131B is supported by the side cover 161B so as to be rotatable about an axis so as to extend in a direction orthogonal to the motor shaft 110.

The movable swash plate 130B can swing around the swing center in accordance with the rotation of the support shaft 131B around the axis.
Specifically, as shown in FIG. 12, the hydraulic motor unit 100B includes a swing arm 132B that operatively connects the support shaft 131B and the movable swash plate 130B, and a control provided at the operation end of the support shaft 131B. Arm 135B.

The swing arm 132B is supported at its base end portion so as not to rotate relative to the support shaft 131B, and an engagement portion 132B ′ for engaging with the side portion of the movable swash plate 130B is provided at the distal end portion. ing.
In the present embodiment, an engagement groove 130B ′ is formed on a side portion of the movable swash plate 130B, and the engagement portion 132B includes an engagement protrusion engaged with the engagement groove 130B ′. Has been.
The control arm 135B is supported at its base end portion so as not to rotate relative to the support shaft 131B, and its tip end portion is operatively connected to the steering member 5.

  With this configuration, when the control arm 135B is swung around the support shaft 131B in accordance with the operation of the steering member 5, the support shaft 131B rotates about the axis, thereby the swing arm 132B. The movable swash plate 130B swings around the swing center via the.

Preferably, the hydraulic motor unit 100B may include a reference position return mechanism 180B that holds the movable swash plate 130B at a reference tilt position when the operating force to the control arm 135B is released.
As shown in FIG. 12, the reference position return mechanism 180B includes a biasing member that biases the movable swash plate 130B to one side around the swing center, and the movable swash plate 130B biased by the biasing member. And a reference position setting member that defines a rocking end on one side around the rocking center.

  The urging member includes, for example, the support shaft 131B that is rotatable about an axis, and the support shaft and the support shaft 131B so that the movable swash plate 130B is tilted about a swing center by rotation of the support shaft about the axis. The movable swash plate 130B is interposed between a connecting member for operatively connecting the movable swash plate 130B (the swing arm 132B in the illustrated embodiment).

In the present embodiment, the biasing member includes a movable pin 181 provided on the swing arm 132B, a fixed pin 182 provided on the side cover 161B, and a string winding wound around the support shaft 131B. And a spring 183.
The string spring 183 is arranged such that one end and the other end are sandwiched between the fixed pin 182 and the movable pin 181.
That is, the string spring 183 has one end engaged with the fixed pin 182 and the other end engaged with the movable pin 181, so that the swing arm 132 </ b> B is engaged with the support shaft. It is biased to one side around the axis of 131B (counterclockwise direction in FIG. 12).

In the present embodiment, as shown in FIG. 12, the reference position setting member engages with the swing arm 132B, thereby swinging the movable swash plate 130B biased by the bias member. The swing end on one side around the center is shown.
Specifically, in the present embodiment, a stopper pin 185 provided on the side cover 161B is provided as the reference position setting member so as to be able to engage with the swing arm 132B.

Preferably, the reference position setting member is configured to be able to change the swing end position on one side around the swing center of the movable swash plate from the outside of the motor case.
Specifically, the stopper pin 185 includes a base portion 187 supported by the motor case 160 so as to be able to rotate around an axis line according to an external operation, and an engaging portion that rotates around the axis line of the base portion 187 together with the base portion 187. 186, and an engaging portion 186 that engages with the swing arm 132B. The engaging portion 186 is an eccentric pin that is eccentric with respect to the base portion 187.
By providing such a configuration, it is possible to adjust the position of the engaging portion 186 by rotating the base portion 187 around the axis and fixing it at an arbitrary rotational position. Therefore, the swing end of the swing arm 132B (that is, the reference position of the movable swash plate 130B) can be easily adjusted.

By providing the reference position return mechanism 180B having such a configuration, when the control arm 135B is swung to the other side around the axis of the support shaft 131B against the urging force of the chord spring 183, it responds accordingly. Thus, the movable swash plate 130B tilts to one side around the swing center. Therefore, the tilt position of the movable swash plate 130B can be easily changed according to the operation amount of the steering member 5.
Further, according to the above configuration, the movable swash plate 130B is held at the reference tilt position in a state where no operating force is applied to the steering member 5. Therefore, it can also be used as a device that adjusts and fixes the suction / discharge amount of the second hydraulic motor main body 620 to a predetermined value regardless of the operation amount of the steering member 5.
Preferably, the control arm 135B can be attached to and detached from the support shaft 131B. When the suction / discharge amount of the second hydraulic motor main body 620 is substantially constant, the control arm 135B is removed. be able to.

Embodiment 2
Hereinafter, other embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 13 shows a hydraulic circuit diagram of a working vehicle 1B to which the second embodiment of the present invention is applied.
The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The working vehicle 1A to which the first embodiment is applied is a full time in which the first axle driving device 50 and the second axle driving device 60 are always fluidly connected in series to the hydraulic pump main body 420. Although the work vehicle 1B to which the present embodiment is applied is configured to be a four-wheel drive type, the first and second axle drive devices 50 and 60 can be switched between a drive state and a non-drive state, respectively. Wheel drive / four wheel drive switchable type.

  Specifically, the working vehicle 1B includes, in addition to the configuration of the working vehicle 1A, a first axle ON / OFF valve 910 that selectively drives or does not drive the first axle driving device 50; A second axle ON / OFF valve 920 for selectively driving or not driving the second axle driving device 60;

  The first axle ON / OFF valve 910 fluidly connects the pump-side forward high-pressure pipe 311F to the first axle-side forward high-pressure pipe 321F and connects the first axle-side backward high-pressure pipe 321R to the second axle. The first axle drive position for fluidly connecting to the axle-side advance high-pressure pipe 331F to drive the first axle drive device 50, and the pump-side advance high-pressure pipe 311F are connected to the second axle-side advance high-pressure pipe 331F. A first axle non-drive position in which the first axle drive device 50 is brought into a non-drive state by fluidly connecting to the first axle side forward high pressure pipe 321F and the first axle side reverse high pressure pipe 321R. It is comprised so that it can take.

  The second axle ON / OFF valve 920 fluidly connects the first axle-side reverse high-pressure pipe 321R to the second axle-side forward high-pressure pipe 331F and the second axle-side reverse high-pressure pipe 331R. A second axle drive position for fluidly connecting the pump side reverse travel high pressure pipe 311R to drive the second axle drive device 60, and the first axle side reverse travel high pressure pipe 321R are connected to the pump side reverse travel high pressure pipe 311R. A second axle non-driving position for fluidly connecting the second axle side forward high pressure pipe 331F and the second axle side reverse high pressure pipe 331R to drain the second axle driving device. It is comprised so that it can take.

  In the present embodiment, the first axle ON / OFF valve 910 and the second axle driving ON / OFF valve 920 are provided. However, either one of the ON / OFF valves is provided depending on the specification. It is also possible to delete it.

FIG. 1 is a side view of a working vehicle to which the first embodiment of the present invention is applied. FIG. 2 is a plan view of the working vehicle shown in FIG. FIG. 3 is a hydraulic circuit diagram of the working vehicle shown in FIGS. 1 and 2. FIG. 4 is a longitudinal sectional view of the first wheel motor device in the working vehicle shown in FIGS. 1 to 3. FIG. 5 is a longitudinal sectional view of a port block in the first wheel motor device shown in FIG. FIGS. 5A and 5B show the port block of the first wheel motor device on the left side and the port block of the first wheel motor device on the right side, respectively. FIG. 6 is a longitudinal sectional view of a modified example of the port block. FIGS. 6A and 6B show a port block of the first wheel motor device on the left side and a port block of the first wheel motor device on the right side, respectively. FIG. 7 is a longitudinal sectional view of still another modification of the port block. FIGS. 7A and 7B show a port block of the first wheel motor device on the left side and a port block of the first wheel motor device on the right side, respectively. FIG. 8 is a longitudinal sectional view of still another modified example of the port block. FIGS. 8A and 8B show a port block of the first wheel motor device on the left side and a port block of the first wheel motor device on the right side, respectively. FIG. 9 is a partial hydraulic circuit diagram of a modified example of the working vehicle shown in FIGS. 1 to 3, and shows a mode in which the first axle drive device of the working vehicle includes a differential lock mechanism. FIG. 10 is a hydraulic circuit diagram of a second axle drive device in the working vehicle shown in FIGS. 10 (a) to 10 (c) respectively show an aspect provided with a mechanical differential gear mechanism, an aspect provided with a pair of wheel motor devices, and an aspect provided with a pair of hydraulic motor bodies fluidly connected to each other. Show. FIG. 11 is a longitudinal sectional view of a second wheel motor device in the second axle drive device shown in FIG. 10 (b). FIG. 12 is a detailed view of the vicinity of the support shaft and the movable swash plate in the second wheel motor device shown in FIG. FIG. 13 is a hydraulic circuit diagram of a working vehicle to which the second embodiment of the present invention is applied.

Explanation of symbols

1A, 1B Work vehicle 21 First drive wheel (front drive wheel)
22 Second drive wheel (rear drive wheel)
30 Drive source 70 Hydraulic steering mechanism (hydraulic actuator)
90 External tank 80 Mower device (work machine)
120 1st hydraulic motor body (front side hydraulic motor body)
125 Shoe 125 ′ Thrust bearing 130 Fixed swash plate 130B Movable swash plate 131B Support shaft 132B Oscillating arm 150B Motor case 181 Movable pin 182 Fixed pin 183 String winding spring 185 Stopper pin 210 Reduction gear mechanism 290 Output member 300 Casing 420 Hydraulic pump main body 620 Second hydraulic motor body (rear hydraulic motor body)
700 Circulation line 710 Suction line 720 Discharge line 730 Return line 740 Bypass line 745 Relief valve 790 Oil cooler

Claims (12)

A drive source, a front drive wheel and a rear drive wheel disposed on the vehicle front side and the rear side, respectively, a front hydraulic motor body disposed on the vehicle front side, and a vehicle rear side A rear hydraulic motor main body, and a common hydraulic pump main body that is operatively driven by the drive source and forms an HST in cooperation with the front hydraulic motor main body and the rear hydraulic motor main body, A hydraulically driven working vehicle configured to operatively drive the front drive wheel and the rear drive wheel by rotational outputs of a hydraulic motor body and the rear hydraulic motor body,
The front hydraulic motor main body and the rear hydraulic motor main body are fluidly connected in series with the hydraulic pump main body,
Of the front hydraulic motor main body and the rear hydraulic motor main body, the hydraulic motor main body located on the upstream side in the flow direction of the HST hydraulic fluid when the vehicle moves forward is such that the free end of the piston is attached to the corresponding swash plate via a shoe A hydraulically-driven work vehicle characterized by being engaged.   Among the front hydraulic motor main body and the rear hydraulic motor main body, the hydraulic motor main body located on the downstream side in the flow direction of the HST hydraulic fluid when the vehicle moves forward is a swash plate having a free end portion of the piston via a thrust bearing. The hydraulic drive work vehicle according to claim 1, wherein the hydraulic drive work vehicle is engaged with the hydraulic drive work vehicle. A work machine that is operatively driven by power from the drive source is disposed outward in the vehicle longitudinal direction from either the front drive wheel or the rear drive wheel,
Of the front hydraulic motor main body and the rear hydraulic motor main body, the hydraulic motor main body on the side close to the working machine is configured to be positioned upstream in the flow direction of the HST hydraulic oil when the vehicle moves forward. A hydraulically driven working vehicle according to claim 1 or 2. An auxiliary pump body that is operatively driven to rotate by rotational power from the drive source;
At least one of the front hydraulic motor main body and the rear hydraulic motor main body outputs a reduction gear mechanism that reduces its rotation output and a rotation output reduced by the reduction gear mechanism toward a corresponding drive wheel. A wheel motor device is configured together with an output member, a casing for housing the hydraulic motor main body and the reduction gear mechanism,
In the casing, a motor space capable of storing oil that contains the hydraulic motor main body is liquid-tightly divided with respect to a gear space that houses the reduction gear mechanism,
4. The apparatus according to claim 1, wherein at least a part of the oil discharged from the auxiliary pump body is configured to return to the suction side of the auxiliary pump body through the motor space. 5. The hydraulically driven working vehicle as described. An external tank serving as an oil source for the auxiliary pump body;
A circulation line forming a circulation path including the external tank, the auxiliary pump body, and the motor space;
The hydraulically-driven work vehicle according to claim 4, further comprising an oil cooler inserted in the circulation line. The circulation line has one end fluidly connected to the external tank and the other end fluidly connected to the suction side of the auxiliary pump body, and one end fluidly connected to the discharge side of the auxiliary pump body. And a discharge line whose other end is fluidly connected to the motor space, and a return line whose one end is fluidly connected to the motor space and whose other end is fluidly connected to the external tank,
6. The hydraulic drive type work according to claim 5, wherein the discharge line is configured to supply hydraulic oil to the hydraulic actuator and supply return oil from the hydraulic actuator to the motor space. Vehicle.   The hydraulic drive type work according to claim 6, wherein the discharge line is configured to supply surplus oil for the hydraulic actuator to the motor space in addition to return oil from the hydraulic actuator. Vehicle. The circulation line has one end fluidly connected to the external tank and the other end fluidly connected to the suction side of the auxiliary pump body, and one end fluidly connected to the discharge side of the auxiliary pump body. And a discharge line whose other end is fluidly connected to the motor space, and a return line whose one end is fluidly connected to the motor space and whose other end is fluidly connected to the external tank,
6. The hydraulic drive work vehicle according to claim 5, wherein the discharge line is configured to supply hydraulic oil to the hydraulic actuator and to supply surplus oil for the hydraulic actuator to the motor space. . The oil cooler is inserted in the return line,
A bypass line whose one end is fluidly connected to the discharge line and the other end is fluidly connected to the return line downstream of the oil cooler in the oil flow direction, and the maximum oil pressure of the discharge line is set. The hydraulically driven working vehicle according to any one of claims 6 to 8, further comprising a relief valve interposed in the bypass line. The common hydraulic pump body is a variable displacement type,
One of the vehicle front side hydraulic motor main body and the vehicle rear side hydraulic motor main body is a fixed volume type cooperating with a fixed swash plate, and the other is a variable volume type cooperating with a movable swash plate,
The motor case that accommodates the variable displacement hydraulic motor main body has a support shaft and a base end portion that are supported by the support shaft so as not to rotate relative to each other, and a tip end portion that engages with a side portion of the movable swash plate. A movable arm, a biasing member that urges the movable swash plate to one side around a swing center, and a swing on one side around the swing center of the movable swash plate biased by the biasing member. 10. The hydraulically driven working vehicle according to claim 1, further comprising a reference position setting member that defines an end.   11. The hydraulically driven working vehicle according to claim 10, wherein the reference position setting member is capable of changing the position of the swing end from the outside of the motor case. The end of the support shaft opposite to the side supporting the swing arm extends to the outside of the motor case,
11. The movable swash plate is configured to be operable to the other side around a swing center against an urging force of the urging member via an outer end portion of the support shaft. 11. A hydraulically driven working vehicle according to 11.

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