JPH0788885B2 - Hydraulic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objects of the Invention (1) Field of Industrial Application The present invention relates to a hydraulic transmission, and particularly to a motor cylinder having a large number of motor plungers slidable in a ring arrangement on a motor cylinder connected to an output shaft. A large number of pump plungers are slid in a ring arrangement on the hydraulic cylinder that is slidably contacting the swash plate and the pump cylinder that is connected to the input shaft, and each pump plunger is slid on the pump swash plate that interlocks with the motor cylinder. Is connected to form a closed hydraulic circuit, and the pump cylinder communicates with a sliding contact portion of the pump and defines the motor cylinder to define an oil-tight chamber in which the pump swash plate and the pump plunger are arranged. The present invention relates to a transmission device of a type surrounded by.

(2) Conventional Technology Conventionally, a hydraulic transmission device of this type is disclosed in, for example, Japanese Patent Laid-Open No.
It is known as disclosed in Japanese Patent Publication No. 76357.

(3) Problems to be Solved by the Invention By the way, in such a hydraulic transmission, even if the suction port and the discharge port of the hydraulic pump are short-circuited via the clutch valve, the hydraulic pump sucks in accordance with the operation of the input shaft. , Discharges. Therefore, at low temperature when the viscosity of the hydraulic oil rises compared to normal temperature, for example, when trying to rotationally operate the input shaft by starting the engine, the suction and discharge of the hydraulic pump will occur despite the clutch valve short-circuiting. The momentary load generated by the action becomes large, and it may not be possible to smoothly start the engine with a relatively small initial input such as a starter.

The present invention has been made in view of such circumstances, and when the input / output shaft is stopped, the hydraulic oil on the suction side of the hydraulic pump can be smoothly discharged to the oil tank side by gravity so that the load at the start of the input shaft can be reduced. An object of the present invention is to provide a hydraulic transmission device that can be reduced in amount and can hold a required amount of hydraulic oil on the low pressure side of a hydraulic closed circuit after completion of starting.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the present invention, an annular chamber provided in a motor cylinder and communicating with a suction port of a hydraulic pump is communicated with an oil tank. At least three holes are bored in the motor cylinder at equal intervals in the circumferential direction, and each of the holes opens when the oil pressure at the suction port becomes a predetermined value or less, and the working oil is supplied to the oil tank. A control valve for discharging to the side is provided, and the control valve is arranged so as to be movable in the radial direction of the motor cylinder and so that the biasing force always acts inward in the radial direction to increase the hydraulic pressure of the suction port. Accordingly, a valve body that moves outward in the radial direction and a valve opening that is closed at the outward movement limit of the valve body are provided.

(2) Action When the input and output shafts are stopped, each control valve is held in the open state according to the decrease in the hydraulic pressure at the suction port of the hydraulic pump. Moreover, at this time, at least one hole may be located at the lower part of the motor cylinder and the other at least one hole may be located at the upper part of the motor cylinder, regardless of the rotational position of the motor cylinder. Therefore, while permitting the inflow of air to the suction side of the hydraulic pump through the control valve of the hole at the high position, the hydraulic oil can be gravity-smoothed from the suction side of the pump to the oil tank side through the control valve of the hole at the low position. In addition, it can be reliably discharged. As a result, when the input shaft is restarted to cause the hydraulic pump to perform suction / discharge operations, the suction resistance of the hydraulic pump can be minimized and the starting load can be effectively reduced.

Further, in particular, when the control valve is configured as described above, in the rotating state of the motor cylinder after the completion of start, the valve closing force of the valve body is assisted by the centrifugal force received by the valve body of the control valve that rotates integrally with the control cylinder. As a result, each control valve can be accurately held in its closed position, so that it is possible to effectively prevent the control valve from accidentally opening due to vibration or the like.

(3) Embodiment Hereinafter, one embodiment in which the present invention is applied to a vehicle hydraulic continuously variable transmission will be described with reference to the drawings. First, in FIG. 1, a vehicle hydraulic continuously variable transmission CVT is illustrated. A constant displacement hydraulic pump P connected to the input shaft 2 driven by an engine and a variable displacement hydraulic motor M arranged on the same axis as the hydraulic pump P constitute a closed hydraulic circuit C. The hydraulic motor M is connected to the wheels W via the output shaft 11, the forward / reverse gear device G, the counter shaft 18 and the differential device D. The continuously variable transmission CVT is
It is housed in a mission case 1 formed by connecting two case halves 1a and 1b.

The hydraulic pump P includes a pump cylinder 4 connected to the input shaft 2 by a spline 3 and a large number of cylinder holes arranged in an annular array in the pump cylinder 4 so as to surround the input shaft 2.
A large number of plungers 6, 6, which are respectively slidably attached to 5, 5 ,. Power from the engine is transmitted to the input shaft 2 via the flywheel 7.

On the other hand, the hydraulic motor M is provided with a motor cylinder 8 concentrically surrounding the pump cylinder 4 of the hydraulic pump P so as to be able to rotate relative thereto, and the motor cylinder 8
, A large number of motor plungers 10, which are slidably fitted into a large number of cylinder holes 9, 9 ...
10 and are provided.

An output shaft 11 is coaxially projected on one end of the motor cylinder 8 in the axial direction, and a support shaft 12 is coaxially projected on the other end. Output shaft 11
Is supported on the end wall of one case half body 1a via a needle bearing 13, and the support shaft 12 is supported on the end wall of the other case half body 1b via a ball bearing 14.

The input shaft 2 penetrates the end wall of one case half 1a in an oil-tight manner and is arranged concentrically within the output shaft 11. Moreover, a plurality of needle bearings 15 are provided between the inner surface of the output shaft 11 and the outer surface of the input shaft 2, so that the input shaft 2 and the pump cylinder 4 are relatively opposed to the output shaft 11 and the motor cylinder 8. It is rotatable.

Between the output shaft 11 and a sub shaft 18 which is rotatably supported on both end walls of the transmission case 1 in parallel with the output shaft 11 via roller bearings 16 and ball bearings 17,
Forward and reverse gear units G are provided.

The forward and reverse gear device G includes a pair of drive gears 19 and 20 fixed to the output shaft 11 and one drive gear 19 to mesh with the auxiliary shaft 1
A driven gear 21 rotatably supported by 8 and a driven gear 21 rotatably supported by a counter shaft 18 corresponding to the other drive gear 20.
22 and an intermediate gear meshing with the driving gear 20 and the driven gear 22.
23, a driven clutch toothed wheel 24 fixed to the counter shaft 18 between drive clutch toothed wheels 21a, 22a integrally provided at opposing portions of both driven gears 21, 22, and the driven clutch toothed wheel 24 and both drives. A clutch member 25 for selectively connecting the clutch teeth 21a and 22a is provided, and a shift fork 26 is engaged with the clutch member 25 to selectively operate the clutch member 25.

A gear 28 meshed with the input gear 27 of the differential device D is attached to the counter shaft 18.
Are integrally provided, and the differential device D is switched and driven in the forward direction and the reverse direction of the vehicle in accordance with the operation of the clutch member 25.

In FIG. 2, an oil-tight chamber 31 is defined between the motor cylinder 8 and the pump cylinder 4 of the hydraulic pump P. Inside the oil-tight chamber 31, inside the motor cylinder 8, the end face of the pump cylinder 4 is formed. Opposing swash plates 32 are supported. This swash plate
An annular shoe 33 is slidably contacted with 32.

Each of the plungers 6, 6 ... And the shoe 33 are swingably connected via a connecting rod 44, and the inner peripheral step of the shoe 33 is supported by the motor cylinder 8 via a roller bearing 42. The retainer ring 34 is in contact with the retainer ring 34, and the retainer ring 34 is in contact with the spring holder 35 connected to the input shaft 2 via the spline 36 in order to allow axial movement and prevent relative rotation. Further, a coil spring 37 surrounding the input shaft 2 is interposed between the spring holder 35 and the pump cylinder 4, and the spring force of the coil spring 37 causes the spring holder.
The shoe 35 elastically presses the shoe 33 toward the swash plate 32 via the holding ring 34. Moreover, the spring holder 35 and the pressing ring 34 are in spherical contact with each other, and the spring holder 35 evenly contacts the pressing ring 34 to transmit the elastic force of the coil spring 37 to the pressing ring 34.

The oil-tight chamber 31 includes the shoe 33, the pressing ring 34, and the spring holder.
By 35, the first chamber 31a on the swash plate 32 side and the pump cylinder 4
It is partitioned into the second chamber 31b on the side.

The inner peripheral side of the sliding surface between the swash plate 32 and the shoe 33 faces the first chamber 31a, and the lubricating oil leaked from the sliding surface is in contact with the first chamber 31a.
flow to a. By the way, in order to achieve lubrication between the swash plate 32 and the shoe 33, an annular hydraulic pocket 38 is provided on the front surface of the shoe 33.
33, the connecting rod 44 and the oil holes 39, 4 bored in the plunger 6
Each plunger 6 and pump cylinder 4 via 0, 41
It communicates with a pump chamber 45 defined between them. Therefore, the pressure oil in the pump chamber 45 is supplied to the hydraulic pocket 38 through the oil holes 41, 40, 39. As a result, the sliding surfaces of the shoe 33 and the swash plate 32 are lubricated. At the same time, the hydraulic pressure in the hydraulic pocket 38 exerts a pressure on the shoe 33 so as to receive the projecting thrust of the plunger 6, so that the contact pressure between the shoe 33 and the swash plate 32 is reduced.

On the other hand, the motor-side cylinder 8, the swash plate 32, the shoe 33 and the roller bearing 42 form an annular lubrication chamber 43 surrounding the sliding surface so as to face the outer peripheral side of the sliding surface between the swash plate 32 and the shoe 33. The lubricating chamber 43 is defined as the second chamber 31.
Form part of b.

In the lubrication chamber 43, the pressure oil in the hydraulic pocket 38 constantly leaks through the sliding surface between the shoe 33 and the swash plate 32, and after the leakage oil fills the lubrication chamber 43, the second oil passes through the roller bearing 42. It flows to the side of chamber 31b. Therefore, new lubrication oil is always held in the lubrication chamber 43, and the shoe 33
Also, the sliding surface of the swash plate 32 can be surely lubricated from the outside of the shoe 33.

In addition to the oil from the lubricating chamber 43, leaked oil from the sliding surfaces of the plunger 6 and the cylinder hole 5 and the sliding surfaces of the pump cylinder 4 and the distribution board 46 flows into the second chamber 31b.

A communication passage 47 that communicates between the first chamber 31a and the second chamber 31b is bored in the spring holder 35. Further, between the output shaft 11 and the output shaft 2 of the motor cylinder 8, the first chamber 31a communicating with the first chamber 31a is connected.
A discharge path 48 is formed, and the first discharge path 48 is a second discharge path.
It is connected to an oil tank (not shown) provided at the bottom of the mission case 1 via 49, the pressure control valve 50 and the third discharge passage 51.

The pressure control valve 50 opens when the oil pressure in the oil tight chamber 31 exceeds a set value, and adjusts the oil pressure in the oil tight chamber 31 to a predetermined value.

Bevel gears 61, 62 meshing with each other are fixedly provided at opposing ends of the pump cylinder 4 and the shoe 33. These bevel gears 6
1, 62 are formed as synchronous gears with the same number of teeth, and when the pump cylinder 4 rotates together with the input shaft 2, the shoe
33 is rotationally driven synchronously via bevel gears 61 and 62. As a result, the plunger 6 running on the upside of the inclined surface of the swash plate 32
Is given a discharge stroke from the swash plate 32 through the connecting rod 44, and the plunger 6 running on the downward side of the inclined surface is given a suction stroke.

In the hydraulic motor M, an annular motor swash plate 63 that faces the motor cylinder 8 is fitted to an annular swash plate holder 64. The swash plate holder 64 integrally includes a pair of trunnion shafts 65 projecting to both outer sides thereof, and the trunnion shafts 65 are pivotally supported by the mission case 1. Therefore, the motor swash plate 63 can be tilted around the axis of the trunnion shaft 65 together with the swash plate holder 64.

The tip of each motor plunger 10 is swingably connected to a plurality of motor shoes 66 that are in sliding contact with the motor swash plate 63. Moreover, in order to maintain the sliding contact state of each motor shoe 66 with the motor swash plate 63, a holding plate that presses the back surface of each motor shoe 66.
67 is rotatably supported by a ring 69 fixed to the swash plate holder 64 with bolts 68. The connecting portion between each motor shoe 66 and each motor plunger 10 has a holding plate at a plurality of circumferential positions.
It penetrates through 67, so that the holding plate 67 rotates together with the motor shoe 66.

Each motor shoe 66 is provided with a hydraulic pocket 70 on the front surface that is in sliding contact with the motor swash plate 63. On the other hand, each cylinder hole 9
A hydraulic chamber 71 defined between the closed end of the motor plunger 10 and each motor plunger 10 is communicated with the hydraulic pocket 70 through a series of oil holes 72, 73 formed in the motor plunger 10 and the motor shoe 66. . Therefore, the pressure oil in the hydraulic chamber 71 is
It is supplied to the hydraulic pocket 70 through 3 and exerts pressure on the motor shoe 66 so as to receive the protruding thrust of the motor plunger 10. As a result, the motor shoe 66 and the motor swash plate 63 are
The contact pressure therebetween is reduced, and the sliding surfaces of the motor shoe 66 and the motor swash plate 63 are lubricated.

On the inner peripheral surface of the swash plate holder 64, a cylindrical partition wall body 74 that is opposed to the inner peripheral surface of the pressing plate 67 with a small gap is fitted, and the partition wall body 74, the swash plate holder 64, and the pressing plate. Lubrication chamber 75 surrounding the sliding surface of motor shoe 66 and motor swash plate 63 by 67
Is defined.

Thus, the pressure oil in each hydraulic pocket 70 is stored in the motor shoe 66.
Also, the oil constantly leaks through the sliding surface of the motor swash plate 63, and the leaked oil fills the lubricating chamber 75 as lubricating oil and then leaks from the gaps around the holding plate 67. Therefore,
New lubricating oil is always held in the lubricating chamber 75, and the sliding surface of the motor shoe 66 and the motor swash plate 63 can be reliably lubricated from the outside of the motor shoe 66 by the oil.

In this case, when the pressure in the lubrication chamber 75 approaches the pressure in the hydraulic pocket 70, the fluid bearing function of the hydraulic pocket 70 with respect to the motor shoe 66 is impaired, so the lubrication chamber 75 retains oil while maintaining a pressure state close to atmospheric pressure. Hydraulic pocket 70 to
The clearances around the pressing plate 67 are appropriately selected according to the amount of oil leaked from the.

The mission case 1 is provided with a servomotor 81 for tiltably driving the swash plate holder 64, that is, the motor swash plate 63. The servo motor 81 includes a servo cylinder 82 fixed to the mission case 1 and a servo cylinder 82 for dividing the servo cylinder 82 into a left oil chamber 83 and a right oil chamber 84.
Servo piston 85 sliding on 82 and servo piston 85
Piston rod 86 that is integrally provided in the oil cylinder and pierces the end wall of the servo cylinder 82 on the left oil chamber 83 side in an oil-tight and movable manner.
And the tip portion is slid into a valve hole 87 formed in the servo piston 85 and the piston rod 86, and the servo cylinder
And a pilot valve 88 penetrating an end wall of the right side oil chamber 84 side of 82 in an oiltight and movable manner.

The piston rod 86 is connected to the swash plate holder 64 via a pin 89. An oil passage 90 provided in the servo cylinder 82 is always in communication with the left oil chamber 83, and the hydraulic pressure supplied from the oil passage 90 acts on the servo piston 85. In the servo piston 85 and the piston rod 86, a passage 91 for communicating the right side oil chamber 84 with the valve hole 87 according to the right movement of the pilot valve 88, and the right side oil chamber 84 for the left side oil chamber with the left movement of the pilot valve 88. A passage 92 communicating with 83 is provided. Further, the valve hole 87 communicates with the oil tank at the bottom of the mission case 1 via the return path 93.

The servo piston 85 performs an amplification operation by the hydraulic pressure supplied from the oil passage 90 so as to follow the leftward and rightward movements of the pilot valve 88, whereby the swash plate holder 64, that is, the motor swash plate 63, is at the maximum tilt position shown in the figure. And a right-angled position that is perpendicular to each motor plunger 10. At this time, the motor swash plate 63 reciprocates each motor plunger 10 as the motor cylinder 8 rotates to repeat expansion and contraction. The stroke of the motor plunger 10 depends on the inclination of the motor swash plate 63. Is adjusted steplessly.

A hydraulic closed circuit C is formed between the hydraulic pump P and the hydraulic motor M via a distribution board 46 and a distribution ring 97. Thus, when the pump cylinder 4 is rotated by the input shaft 2, the pump chamber 45 of the cylinder hole 5 accommodating the plunger 6 in the discharge stroke.
The high-pressure hydraulic oil discharged from the cylinder is fed to the hydraulic chamber 71 of the cylinder hole 9 accommodating the motor plunger 10 in the expansion stroke. On the other hand, the hydraulic oil discharged from the hydraulic chamber 71 of the cylinder hole 9 accommodating the motor plunger 10 in the contraction stroke returns to the pump chamber 45 of the cylinder hole 5 accommodating the plunger 6 in the suction stroke. During this time, the reaction torque applied to the motor cylinder 8 by the plunger 10 in the discharge stroke via the swash plate 63,
The motor cylinder 8 or the output shaft 11 is rotationally driven by the sum of the reaction torque received by the motor plunger 10 in the expansion stroke from the motor swash plate 63.

In this case, the motor cylinder 8 with respect to the pump cylinder 4
The gear ratio of is given by the following equation.

As is clear from this equation, if the displacement of the hydraulic motor M determined by the stroke of the motor plunger 10 is changed from zero to a certain value, the gear ratio can be changed from 1 to a certain required value.

The motor cylinder 8 is composed of first to fourth portions 8a to 8d divided in the axial direction. The output shaft 11 is integrally provided in the first portion 8a, and the swash plate 32 is provided in the first portion 8a. A cylinder hole 9 is provided in each of the second, third and fourth portions 8b-8d. The third portion 8c constitutes the distribution board 46, and the support shaft 12 is integrally provided on the fourth portion 8d.

The first and second parts 8a and 8b are connected by a plurality of bolts 98, and the second, third and fourth parts 8b to 8d are provided with a plurality of knock pins 99 and 100 at their joints and are positioned in relation to each other. Bolts 101 are integrally connected.

The inner end of the input shaft 2 is supported at the center of the distribution board 46 via a needle bearing 105, and the pump cylinder 4 is elastically brought into sliding contact with the distribution board 46 by a spring 37.

A support plate 107 is fixed to the outer surface side of the end wall of the case half 1b with a bolt 106, and a cylindrical fixed shaft 108 protruding into the support shaft 12 of the motor cylinder 8 is attached to the support plate 107. Are fixedly connected. At the inner end of the fixed shaft 108, a distribution ring 97 that slidably contacts the distribution board 46 is eccentrically supported, and the distribution ring 97 allows the fourth portion 8d of the motor cylinder 8 to be supported.
The hollow portion 109 provided in the inner space is partitioned into an inner chamber 110 and an outer chamber 111. Thus, the outer chamber 111 constitutes the annular chamber of the present invention provided in the motor cylinder 8. On the other hand, the distribution board 46 is provided with discharge and suction ports 112 and 113, and the discharge port 112 connects the pump chamber 45 of the plunger 6 and the inner chamber 110 in the discharge stroke,
The suction port 113 communicates the pump chamber 45 of the plunger 6 in the suction stroke with the outer chamber 111. A large number of communication ports 114, 114 ... Are bored in the distribution board 46, and each hydraulic chamber 71 of the motor cylinder 8 is communicated with the inner chamber 110 or the outer chamber 111 by these communication ports 114, 114. Therefore, when the pump cylinder 4 rotates, the high-pressure hydraulic oil generated by the discharge stroke of the plunger 6 flows into the inner chamber 110 from the discharge port 112, and further, through the communication port 114 communicating with the inner chamber 110, the expansion stroke. Of the motor plunger 10 into the hydraulic chamber 71 of the motor plunger 10
Give thrust to. On the other hand, the motor plunger 10 in the contraction process
The hydraulic oil discharged by means of the communication port 114 communicating with the outer chamber 111 and the suction port 113 flows back to the pump chamber 45 of the plunger 6 in the suction stroke, and the circulation of such hydraulic oil causes the hydraulic oil to flow as described above. Transmission from the hydraulic pump P to the hydraulic motor M is performed.

The side wall of the fixed shaft 108 is provided with, for example, two short-circuit ports 115 capable of communicating between the inner chamber 110 and the outer chamber 111,
Cylindrical clutch valve that opens and closes those short-circuit ports 115 1
16 is rotatably fitted in the fixed shaft 108. The clutch valve 116 is provided with a valve hole 117 corresponding to the short-circuit port 115 on a side wall near the tip thereof, and an operation connecting portion 119 to which an operation shaft 118 connected to a clutch control device (not shown) is connected to a base end portion thereof. To be

Rotate the clutch valve 116 to open the valve hole 117 to the short circuit port 11
When the valve is fully opened, the clutch is off and the valve hole 117
The clutch-on state is obtained when the valve is shifted from the short-circuit port 115 and fully closed, and the half-clutch state is obtained when the valve hole 117 and the short-circuit port 115 are slightly shifted to the half-open state. That is, in the clutch off state, the discharge port 11
The hydraulic oil discharged from 2 to the inner chamber 110 is immediately short-circuited to the outer chamber 11 and the suction port 113 through the short-circuit port 115, and the hydraulic motor M becomes inoperable. In the clutch-on state, the hydraulic oil short-circuits as described above. Is prevented, a circulating action of hydraulic oil from the hydraulic pump P to the hydraulic motor M occurs, and normal transmission is performed.

The clutch valve 116 has a built-in hydraulic servomotor 121 operated by the pilot valve 120.
A valve rod 123 having a diameter smaller than the inner diameter of the clutch valve 116 is provided at the tip portion of 22. The valve rod 123 projects into the inner chamber 110, and has a closing valve 124 for the discharge port 112 at its tip.
Is attached so that it can swing freely. Then, the servo piston 12
The discharge port 112 can be closed by bringing the closing valve 124 into close contact with the distribution board 46 by the left movement of 2. This closing is performed when the motor swash plate 73 is placed in the upright state and the gear ratio is set to 1, whereby the plunger 6 is hydraulically locked and the pump cylinder 4 passes through each plunger 6 and the swash plate 32. The motor cylinder 8 can be mechanically driven,
As a result, the thrust of the motor plunger 10 on the motor swash plate 63 disappears, and the load on each bearing due to the thrust is removed.

An oil passage 139 communicating with the inner chamber 110 and an oil passage 140 communicating with the outer chamber 111 are bored in the fixed shaft 108 and the support plate 107. The support plate 107 has an oil passage 9 connected to the servo motor 81.
An oil passage 141 communicating with 0 is bored and the oil passage 141
And a switching valve 142 for selectively switching the communication state between the oil passages 139 and 140. This switching valve 142 is provided on both oil passages 139,
It operates so that the higher hydraulic pressure of 140 is communicated with the oil passage 141. Therefore, the servo motor 81 for tilting the motor swash plate 63 of the hydraulic motor M includes the inner chamber 110 and the outer chamber 1.
The hydraulic pressure will be supplied from the one with higher hydraulic pressure.

One ends of links 127 and 128 are connected to the pilot valves 88 and 120 of both servo motors 81 and 121, and the other ends of the links 127 are linked and connected to a rotating shaft 129 rotated by an operating means (not shown). Further, a cam 130 is provided on the rotating shaft 129, and a cam follower 131, which is in sliding contact with the cam 130, is provided at the other end of the link 128. As a result, when the servo motor 81 is operated to put the motor swash plate 63 in the upright state, the servo motor 121 operates so that the discharge port 112 is blocked by the blocking valve 124.

A supply pump F is provided outside the end wall of the case half 1a. The replenishment pump F is driven by the input shaft 2, pumps oil from the oil tank at the bottom of the transmission case 1, and through the replenishment oil passage 137 and the check valve 138 provided in the input shaft 2. Supply hydraulic fluid to the hydraulic closed circuit C.

In FIG. 3, the second portion 8b of the motor cylinder 8 is shown.
Is formed with a hole 172 extending in the radial direction so as to communicate between the second chamber 31b in the oil tight chamber 31 and the oil tank at the inner bottom of the mission case 1. The hole 172 has an oil tight chamber.
Discharge valves 170 are provided to open the valve 31 when the hydraulic pressure in the chamber 31 becomes a predetermined value or less and to discharge the hydraulic oil in the chamber 31 to the oil tank side. Each hole 172 is formed as a stepped hole in which a female screw is engraved on the small diameter side.

The discharge valve 170 has a closed bottom cylindrical holder 173 screwed into a hole 172 with its closed end facing the second chamber 31b, and a valve chamber 174 between the open end of the holder 173 and the holder 173. And a closing member 176 having a valve port 175 and a spherical valve body housed in the valve chamber 174 and movable in the radial direction of the motor cylinder 8.
177 and a spring 178 housed in the valve chamber 174 for biasing the valve body 177 in the valve opening direction (that is, inward in the radial direction of the motor cylinder 8). When the outer limit of movement is reached, which contacts the inner end of the closing member 176, the valve opening 175
The hole 172 can be blocked by closing. The holder 173 is configured by coaxially connecting a small-diameter portion screwed into the small-diameter hole portion of the hole 172 and a large-diameter portion fitted into the large-diameter hole portion of the hole 172, and blocking the same. Valve chamber 17 at the end
A communication hole 179 for communicating 4 with the second chamber 31b is formed. Further, the valve body 177 is formed to have a diameter such that a slight gap is formed between the valve body 177 and the inner surface of the holder 173.
When the 75 is not closed, the communication hole 179 and the valve port 175 communicate with each other.

In the discharge valve 170, when the hydraulic pressure in the second chamber 31b in the oil tight chamber 31 is higher than the set pressure determined by the spring 178, the hydraulic valve receives the hydraulic pressure and is held in the closed state, and the hydraulic pressure is lower than the set pressure. At some times, the valve is opened based on the biasing force of the spring 178, and the oil in the second chamber 31b is discharged to the oil tank at the bottom inside the mission case 1.

In FIG. 4, an outer chamber 111 forming a part of an oil passage connecting the suction port of the hydraulic pump P and the discharge port of the hydraulic motor M.
In the fourth portion 8d of the motor cylinder 8 facing the outer chamber 111
And at least three holes 180 for communicating between the oil tank at the bottom of the mission case 1 and the oil tank at the inner bottom of the mission case 1 are formed at equal intervals in the circumferential direction. A control valve 181 for opening the valve to discharge the hydraulic oil in the chamber 111 to the oil tank side is provided when the following occurs.

The control valve 181 has a valve body 183 formed of an elastic material in a plate shape, and a valve opening 180a provided at the inner opening end of the hole 180 and opened and closed by the valve body 183. The base end of the valve body 183 is fixed to the inner surface of the fourth portion 8d by a screw member 182. The tip of the valve body 183 is the motor cylinder 8
Can be swung in the radial direction, and due to its own elastic force, a biasing force acts on the side away from the valve opening 180a (radially inward side). Thus, the valve body 183 can swing outward in the radial direction of the motor cylinder 8 in response to an increase in the hydraulic pressure in the outer chamber 111, and when the hydraulic pressure exceeds a predetermined value, the valve body 183 opens the valve. The valve opening 180a is closed in close contact with the opening end of 180a (that is, when the swing limit toward the outside is reached). Also the outer chamber
When the hydraulic pressure of 111 decreases and becomes smaller than the predetermined value, the control valve 181 swings inward in the radial direction of the motor cylinder 8 by its own elastic force to open the valve port 180a, whereby the outer chamber is opened.
The hydraulic oil in 111 is discharged from the hole 180.

Referring again to FIG. 2, the distribution board 46 is provided with an oil passage 151 communicating with the supply oil passage 137 and an oil passage 152 communicating with the second chamber 31b in the oil-tight chamber 31, and a relief is provided between the oil passages 151,152. Valve 15
0 is inserted. The relief valve 150 opens when the oil pressure in the supply oil passage 137 becomes higher than a predetermined value, and the relief oil passage 137 is opened.
The oil relieved from 137 is guided to the oil-tight chamber 31.

The operation of this embodiment will now be described. During normal operation of the hydraulic continuously variable transmission CVT when the engine is in operation, oil leaked from the sliding contact portions of the hydraulic pump P and oil relieved from the relief valve 150 are removed. , The oil-tight chamber 31 is filled.
At this time, since oil is successively supplied to the oil tight chamber 31, the oil pressure in the oil tight chamber 31 is higher than the set value of the discharge valve 170, and therefore the discharge valve 170 is in the closed state. When accelerating, the check valve is filled with supplemental oil equivalent to the amount of oil leaking from the hydraulic closed circuit C.
Since it is replenished via 138, the differential pressure across the control valve 181 in the outer chamber 111 becomes greater than the set value, and the control valve 181 closes. Further, during deceleration, high-pressure oil discharged from the hydraulic motor M that acts as a pump is supplied to the outer chamber 111, so that the oil pressure in the outer chamber 111 is high and the control valve 181 remains closed. Therefore, the outer chamber 111
The hydraulic pressure is high and the control valve 181 is closed.

Therefore, in the normal operation state of the continuously variable transmission CVT as described above, the motor cylinder 8 of the hydraulic motor M is often in a rotating state, and therefore, the discharge valve 170 and the control valve installed in the motor cylinder 8 are The valve closing force is assisted by the centrifugal force applied to the valve bodies 177 and 183 of the valve body 177 and 183 in a relationship that the moving limit of the valve bodies 177 and 183 to the outside in the radial direction of the motor cylinder is the valve closing position. As a result, the valves 170 and 181 are surely kept closed during engine operation.
From the oil-tight chamber 31 and the outer chamber 111 to the oil tank side Valves 170, 1
No hydraulic fluid leaks through 83.

When the engine is stopped, the hydraulic oil hardly leaks from the sliding contact portions of the hydraulic pump P, and the replenishment pump F is also inactive. Therefore, the oil tight chamber 31 is released through the relief valve 150.
There is also no oil supplied to. Therefore, the differential pressure across the discharge valve 170 falls below the set value of the discharge valve 170, and the discharge valve 1
The valve 70 is opened, and the oil in the oil-tight chamber 31 is discharged to the oil tank at the bottom inside the mission case 1. At this time, since the three exhaust valves 170 are arranged at equal intervals in the circumferential direction, at least one exhaust valve 1 is sucked in from at least one exhaust valve 170 regardless of the position of the motor cylinder 8 when stopped.
Oil can be efficiently discharged from 70.

Further, since the hydraulic pressure is not supplied to the outer chamber 111, the control valve 181
The differential pressure between the front and rear drops below the set value, and the control valve 181 opens,
The oil in the outer chamber 111 is discharged to the oil tank. On this occasion,
Like the discharge valve 170, three control valves 181 are arranged at equal intervals in the circumferential direction, so that oil can be discharged efficiently.

When the engine is started, the oil in the oil-tight chamber 31 is discharged as described above while the engine is stopped. Therefore, the plunger 6 of the hydraulic pump P connected to the engine and the connecting rod 44 stir the oil in the oil-tight chamber 31. No resistance occurs. Therefore, the stirring resistance does not occur even if the viscosity of the oil increases at low temperatures.

In addition, since the oil in the outer chamber 111 is sufficiently discharged while the engine is stopped, the suction resistance at the moment when the hydraulic pump P connected to the engine is started becomes small. Therefore, even if the viscosity of the oil increases at low temperatures, the instantaneous suction resistance immediately after the engine starts can be reduced.

In this way, the engine can be started smoothly at a low temperature without requiring a particularly large initial input by the starter or the like at the time of engine start, and the same operation as in the conventional case can be obtained during normal operation.

C. Effects of the Invention As described above, according to the present invention, at least three holes for communicating the annular chamber, which is provided in the motor cylinder and communicates with the suction port of the hydraulic pump, with the oil tank, are provided in the motor cylinder in the circumferential direction. Are drilled at equal intervals in each hole,
Since a control valve that opens when the oil pressure of the suction port becomes a predetermined value or less and discharges the working oil to the oil tank side is provided,
When the input and output shafts are stopped, each control valve can be held in an open state according to the decrease in the hydraulic pressure at the suction port of the hydraulic pump, and at this time, the motor cylinder remains stationary at any rotational position. However, since at least one hole can be located in the lower part of the motor cylinder and the other at least one hole can be located in the higher part of the motor cylinder,
While allowing air to flow into the suction side of the hydraulic pump through the control valve in the high position hole, the control valve in the low position hole allows the hydraulic oil to smoothly and reliably flow from the suction side of the pump to the oil tank side by gravity. Therefore, when the input shaft is restarted to cause the hydraulic pump to perform suction / discharge operations, the suction resistance of the hydraulic pump can be minimized to effectively reduce the starting load. Even at a low oil temperature when the viscosity of the hydraulic oil increases, the starting can be performed without difficulty.

Further, in particular, the respective control valves are arranged so as to be movable in the radial direction of the motor cylinder and so that the biasing force always acts inward in the radial direction thereof, and in the radial direction outward in response to an increase in hydraulic pressure in the oil-tight chamber. Since it has a moving valve body and a valve port that is closed at the limit of outward movement of this valve body, the valve body of the control valve that rotates integrally with the valve body receives it in the rotating state of the motor cylinder after the start is completed. Centrifugal force assists the valve closing force of each valve element, and each control valve can be accurately held in its closed position. Therefore, it is possible to effectively prevent the control valve from opening inadvertently due to vibration or the like. Therefore, it is possible to suppress the leakage of oil from the control valve to the oil tank side and hold the required amount of hydraulic oil on the low pressure side of the hydraulic closed circuit, and also the deceleration operation where the low pressure side becomes high pressure. The engine braking effect is always effective even when Rukoto can.

[Brief description of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a vertical sectional side view of a vehicle hydraulic continuously variable transmission to which the present invention is applied.
FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is III-I of FIG.
II line enlarged sectional view, FIG. 4 is an IV-IV line enlarged sectional view of FIG. 2 ... Input shaft, 4 ... Pump cylinder, 6 ... Pump plunger, 8 ... Motor cylinder, 10 ... Motor plunger, 11 ...
Output shaft, 31 ... Oil-tight chamber, 32 ... Pump swash plate, 63 ... Motor swash plate, 180 ... Hole, 180a ... Valve port, 181, ... Control valve, 183 ... Valve body, 1
11 ... Outer chamber as annular chamber, C ... Hydraulic closed circuit, M ... Hydraulic motor, P ... Hydraulic pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Nakamura, 1-4-1, Chuo, Wako, Saitama Prefecture, Honda R & D Co., Ltd. (56) Reference JP-A-57-76357 (JP, A) JP 50-48505 (JP, A) Actual 61-32655 (JP, U) Actual 53-162901 (JP, U) Actual 50-82905 (JP, U)

Claims (1)

[Claims] 1. A hydraulic motor (M) comprising a motor swash plate (63) in which a large number of motor plungers (10), which are slidably mounted in an annular arrangement, on a motor cylinder (8) connected to an output shaft (11). ) And a plurality of pump plungers (6) are slid in a ring arrangement on a pump cylinder (4) connected to the input shaft (2), and each pump is attached to a pump swash plate (32) that is interlocked with the motor cylinder (8). A hydraulic pump (P) formed by sliding contact with a plunger (6) is connected to form a closed hydraulic circuit (C), and a pump cylinder (4) communicates with a sliding contact portion of the pump (P) and the pump. In a hydraulic transmission device surrounded by the motor cylinder (8) so as to define an oil-tight chamber (31) in which the swash plate (32) and the pump plunger (6) are arranged, in the motor cylinder (8). Provided with the hydraulic pump At least three holes (180) for communicating the annular chamber (111) communicating with the suction port of P) with the oil tank are formed in the motor cylinder (8) at equal intervals in the circumferential direction. Each hole (180) is provided with a control valve (181) that opens when the oil pressure at the suction port falls below a predetermined value and discharges the operating oil to the oil tank side. A valve element (183) which is arranged so as to be movable in the radial direction of the cylinder (8) and is so arranged that a biasing force always acts inward in the radial direction thereof and moves outward in the radial direction in response to an increase in hydraulic pressure at the suction port. ) And a valve opening (180a) which is closed at the outward movement limit of the valve body (183).