JP4779196B2 - Work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a work vehicle, more particularly, to a hydrostatic continuously variable transmission for a working vehicle is provided separately to the forward pedal reverse pedal.
[0002]
[Prior art and problems to be solved by the invention]
In a relatively small work vehicle, it is known that the rotational power of an engine is changed by a hydrostatic continuously variable transmission (HST). The HST is a combination of a variable hydraulic pump driven by the rotational power of the engine and a hydraulic motor driven by the hydraulic pump, and changes the tilt angle of the hydraulic pump according to the rotation of the trunnion shaft. By changing the discharge amount of the hydraulic pump, the rotation of the hydraulic motor is steplessly changed and output.
[0003]
As means for rotating the trunnion shaft, pedals are respectively fixed on the front and rear sides of the trunnion shaft, and when the front pedal is stepped forward to rotate the trunnion shaft in the forward direction, the HST is driven by forward rotation, and the rear side An integrated pedal type configuration is known in which the HST is driven in the reverse direction when the trunnion shaft is reversely rotated by depressing the pedal backward. In addition, the forward pedal and the reverse pedal are provided separately on separate axes, and one or both pedals are connected to the trunnion shaft by a link mechanism, and the operability is improved by making the forward pedal and the reverse pedal depressed in the same direction. An independent two-pedal configuration is also known.
[0004]
However, in the conventional independent two-pedal type, since the forward pedal and the reverse pedal are provided on separate axes and are connected to the trunnion shaft by a link mechanism, the stroke of the forward pedal for rotating the trunnion shaft to a predetermined angle The reverse pedal stroke was different and the pedal operation was uncomfortable. Further, since each member is attached separately, the assembly and adjustment work is complicated.
[0005]
Therefore, in the independent two-pedal hydrostatic continuously variable transmission in which the forward pedal and the reverse pedal are depressed in the same direction, the forward stroke and the reverse pedal are made to have the same depression stroke to improve the operational feeling. The technical problem to be solved in order to simplify the assembling work arises, and the present invention aims to solve this problem.
[0006]
[Means for Solving the Problems]
The present invention has been proposed to achieve the above object, and the invention according to claim 1 is driven by the rotational power of the engine (11) and discharges according to the rotation of the trunnion shaft (23). Work vehicle (10) equipped with a hydrostatic continuously variable transmission (19) comprising a variable hydraulic pump (21) for changing the amount and a hydraulic motor (22) driven by the hydraulic pump (21) And the pedal support shaft (34) provided on the same axis as the trunnion shaft (23) is supported so that the forward pedal (30) and the reverse pedal (31) can be depressed in the same direction. A link support shaft (38) is provided in parallel with the support shaft (34), and the rotation caused by the depressing operation of either the forward pedal (30) or the reverse pedal (31) is directly transmitted to the trunnion shaft (23). In both cases, the hydrostatic continuously variable transmission for a work vehicle is connected to rotate the trunnion shaft (23) in the reverse direction via a link mechanism formed between the link support shafts (38) by the rotation of the other pedal. In
An opening (32) is provided on one side of the transmission case (13), a bracket (33) is attached to the opening (32), the trunnion shaft (23) is projected, and the pedal is mounted on the bracket (33). The support shaft (34), the link support shaft (38) and the link mechanism are mounted, and a cam (43) having a V-shaped recess is fixed in the vicinity of the transmission case side end of the link support shaft (38). The roller (44) pivotally attached to the transmission case (13) is pressed against the cam (43) by the urging force of the spring (45), near the other end of the link support shaft (38). Since the arm (46) is fixed and the damper (47) is connected, and when the link support shaft (38) is rotated, the cam (43) is returned by the action of the damper (47). Forward pedal (30) or reverse pedal (31) During depression released, the roller (44) is returned to the recess center of the cam (43), configured so that each pedal (30, 31) is held by return to the original position,
Further, the pedal support shaft (34), the link support shaft (38), and the link mechanism are attached to the bracket (33) in an assembled state. Step transmission,
According to a second aspect of the present invention, the hydraulic motor (22) is configured to switch the tilt angle of the internal swash plate in two stages, thereby changing the hydraulic motor (22) according to the discharge amount of the hydraulic pump (21). The rotation amount of the hydraulic pump (21) can be changed to high torque or low torque, and the discharge amount of the instantaneous hydraulic pump (21) that changes the internal swash plate of the hydraulic motor (22) is changed by a motor changeover switch provided on the meter panel. By adjusting the number of rotations of the output shaft to the number of rotations just before the motor switching, the change in vehicle speed before and after shifting is minimized, and shift shock is suppressed, and an electromagnetic brake mechanism is mounted on the trunnion shaft (23). A cruise control switch is provided together with the motor changeover switch, and the electromagnetic brake mechanism is operated by the cruise control switch. 2. The hydrostatic pressure of a work vehicle according to claim 1, wherein the vehicle speed can be kept constant without continuously holding the pedals (30, 31) of the hydrostatic continuously variable transmission (19) with a foot. A continuously variable transmission is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a tractor 10 as an example of a work vehicle. An engine 11 is mounted on the front part of the machine body and covered with a bonnet 12, a mission case 13 is attached to the rear part of the machine body, and a cabin 14 is placed on the upper part thereof. The driver seat 15 is provided in the cabin 14.
[0008]
As shown in FIGS. 1 and 2, a clutch housing 16 is attached to the rear portion of the engine 11, and a main clutch 17 is provided inside the clutch housing 16. An extension mission case 18 is interposed between the clutch housing 16 and the mission case 13, and a hydrostatic continuously variable transmission (HST) 19 is provided in the extension mission case 18. The rotational power of the engine 11 is input to the HST 19 via the main clutch 17, and is steplessly shifted by the HST 19 and then transmitted to the gear-type transmission 20 provided in the transmission case 13. It is.
[0009]
The HST 19 includes a variable hydraulic pump 21 driven by the rotational power of the engine 11 and a hydraulic motor 22 driven by the hydraulic pump 21. The HST 19 depresses a forward pedal 30 or a reverse pedal 31, which will be described later. When the trunnion shaft 23 is rotated, the discharge amount of the hydraulic pump 21 is changed, and the rotation speed of the hydraulic motor 22 is changed steplessly. The rotation of the hydraulic motor is transmitted to the drive shaft 25 through the reduction gear mechanism 24 provided in front of the HST 19 and is shifted by the rear gear-type transmission 20, and then the driving system power is transmitted through the rear differential device 25. The wheel 26 is driven and the front wheel 28 is driven via the front differential device 27. On the other hand, the power of the PTO system is taken out from the PTO output shaft protruding from the rear surface of the mission case 13.
[0010]
FIGS. 3 and 4 show the mounting structure of the forward pedal 30 and the reverse pedal 31 for operating the HST 19. An opening 32 is provided on one side of the additional transmission case 18, and a bracket 33 is attached to the opening 32 to provide a trunnion. The shaft 23 is projected outside. Then, a pedal support shaft 34 is fixed to the tip of the trunnion shaft 23 on the same axis as the trunnion shaft 23, and the trunnion shaft 23 and the pedal support shaft 34 are supported by the bracket 33 so that they can rotate together. At the same time, the forward pedal 30 is fixed to the pedal support shaft 34.
[0011]
A boss 35 is pivotally attached to the distal end portion of the pedal support shaft 34, and a plate 36 is fixed to the boss 35, and the reverse pedal 31 is fixed to the plate 36. The forward pedal 30 and the reverse pedal 31 are formed so that the stepping pressure portions are at the same height, and the reverse pedal 31 rotates about the pedal support shaft 34 together with the boss 35, so that the rotation center of the forward pedal 30 is And the rotation center of the reverse pedal 31 coincide with each other, and the rotation radius of the stepping pressure portion is the same. An arm 37 is fixed to the base end portion of the pedal support shaft 34.
[0012]
Here, a link support shaft 38 is pivotally attached to the bracket 33 in parallel with the pedal support shaft 34. An arm 39 is fixed to one end of the link support shaft 38, and the arm 39 and the plate 36 are fixed. Are connected by a link rod 40. On the other hand, an arm 41 is fixed to the other end of the link support shaft 38, and the arm 37 of the pedal support shaft 34 and the arm 41 are connected by a link rod 42. As described above, the forward pedal 30 and the reverse pedal 31 supported by the pedal support shaft 34 are formed by the link mechanism including the link support shaft 38 and the link rods 40 and 42 provided in parallel to the pedal support shaft 34, and the trunnion shaft. 23.
[0013]
Thus, when the forward pedal 30 is depressed, the pedal support shaft 34 is directly rotated by the forward pedal 30, and the trunnion shaft 23 is rotated in the direction of arrow F integrally with the pedal support shaft 34. The HST 19 is driven by forward rotation. On the other hand, when the reverse pedal 31 is depressed, the boss 35 and the plate 36 are rotated in the direction of arrow F by the reverse pedal 31, the link rod 40 is pulled, and the link support shaft 38 is opposite to the pedal support shaft 34. To turn. Therefore, the link rod 42 is pushed and the pedal support shaft 34 rotates in the direction of arrow R, and the trunnion shaft 23 rotates in the same direction together with the pedal support shaft 34 so that the HST 19 is driven in reverse rotation. .

[0014]
A cam 43 having a V-shaped recess is fixed in the vicinity of the other end of the link support shaft 38, and a roller 44 pivotally attached to the transmission case 13 is pressed against the cam 43 by the spring 45. is doing. In addition, an arm 46 is fixed in the vicinity of one end portion of the link support shaft 38 and a damper 47 is connected. When the link support shaft 38 is rotated, the cam 43 is returned by the action of the damper 47. When the forward pedal 30 or the reverse pedal 31 is released, the roller 44 returns to the center of the recess of the cam 43, and the pedals 30 and 31 are returned to their original positions and held.
[0015]
As described above, the rotation center of the forward pedal 30 and the rotation center of the reverse pedal 31 coincide with each other, and the rotation radius of the stepping pressure portion is the same. Are the same, and there is no sense of incongruity in pedal operation. Since the pedal support shaft 34, the link support shaft 38, and the link mechanism are assembled to the bracket 33, the assembly to the transmission case 13 is extremely easy.
[0016]
Next, control of the HST 19 will be described. As described above, the HST 19 includes the variable hydraulic pump 21 and the hydraulic motor 22 driven by the hydraulic pump 21, but the tilt angle of the internal swash plate of the hydraulic motor 22 is switched in two stages. Thus, the rotation of the hydraulic motor 22 can be changed to high torque or low torque in accordance with the discharge amount of the hydraulic pump 21. Conventionally, since the solenoid valve was switched automatically or manually, the shift shock was large. However, at the moment when the internal swash plate of the hydraulic motor 22 was switched by a motor switch (not shown) provided on the meter panel. By changing the discharge amount of 21 and adjusting the rotation speed of the output shaft to the rotation speed immediately before the motor switching, the change in the vehicle speed before and after the shift becomes small, and the shift shock can be suppressed.
[0017]
Also, wearing the electromagnetic brake mechanism (not shown) on the trunnion shaft 23, the with motors changeover switch may be provided a cruise control switch (cruise Control: switch), by the cruise control switch, the electromagnetic if caused to actuate the brake mechanism, without continuing to hold the HST pedal with a foot, it is possible to maintain the running speed of the vehicle constant.
[0018]
It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.
[0019]
【The invention's effect】
As described in detail in the above embodiment, the invention according to claim 1 is provided with a pedal support shaft on the same axis as the trunnion shaft, and a forward pedal and a reverse pedal are supported on the pedal support shaft. As a result, the turning center of the forward pedal and the turning center of the reverse pedal coincide with each other, and the depression strokes of both pedals become the same, so that the pedal operation does not feel uncomfortable.
[0020]
In the above invention , since the pedal support shaft, the link support shaft, and the link mechanism are assembled to a bracket provided on one side of the mission case, the assembling work to the mission case becomes extremely easy.
In the invention according to claim 2, the hydraulic motor (22) is configured so that the tilt angle of the internal swash plate is switched between two levels, so that the hydraulic motor (22) is in accordance with the discharge amount of the hydraulic pump (21). Since the rotation can be changed to high torque or low torque, it is comfortable without receiving a sense of incongruity of shifting. Then, by changing the discharge amount of the instantaneous hydraulic pump (21) that has switched the internal swash plate of the hydraulic motor (22) by the motor changeover switch, and adjusting the rotational speed of the output shaft to the rotational speed immediately before the motor switching, Since the change in vehicle speed before and after the shift is small, there is no shock associated with the shift.
Further, an electromagnetic brake mechanism is mounted on the trunnion shaft (23), a cruise control switch is provided together with the motor changeover switch, the electromagnetic brake mechanism is operated by the cruise control switch, and the hydrostatic type Since the vehicle speed can be kept constant without continuing to hold the pedals (30, 31) of the step transmission (19) with feet, the burden and labor of the traveling operator can be reduced.
[Brief description of the drawings]
The figure shows an embodiment of the present invention.
FIG. 1 is a side view of a tractor according to an embodiment of the present invention.
FIG. 2 is a developed longitudinal side view showing a configuration of an HST and a mission case.
FIG. 3 is a side view showing a mounting structure for a forward pedal and a reverse pedal.
FIG. 4 is a partially cutaway front view showing a mounting structure for a forward pedal and a reverse pedal.
[Explanation of symbols]
10 tractor 11 engine 13 mission case 19 hydrostatic continuously variable transmission (HST)
21 hydraulic pump 22 hydraulic motor 23 trunnion shaft 30 forward pedal 31 reverse pedal 32 opening 33 bracket 34 pedal support shaft 38 link support shaft 40, 42 link rod

Claims (2)

A variable hydraulic pump (21) driven by the rotational power of the engine (11) and changing the discharge amount according to the rotation of the trunnion shaft (23), and the hydraulic pressure driven by the hydraulic pump (21) A work vehicle (10) equipped with a hydrostatic continuously variable transmission (19) including a motor (22), the pedal support shaft (34) provided on the same axis as the trunnion shaft (23) The forward pedal (30) and the reverse pedal (31) are supported so as to be freely depressed in the same direction, and a link support shaft (38) is provided in parallel with the pedal support shaft (34), and the forward pedal (30) or The rotation caused by the depression of one of the reverse pedals (31) is directly transmitted to the trunnion shaft (23), and the rotation caused by the depression of the other pedal is transmitted between the link support shafts (38). In the hydrostatic continuously variable transmission for a working vehicle which is connected so as to reverse rotate the trunnion shaft (23) via a form links mechanism,
An opening (32) is provided on one side of the transmission case (13), a bracket (33) is attached to the opening (32), the trunnion shaft (23) is projected, and the pedal is mounted on the bracket (33). The support shaft (34), the link support shaft (38) and the link mechanism are mounted, and a cam (43) having a V-shaped recess is fixed in the vicinity of the transmission case side end of the link support shaft (38). The roller (44) pivotally attached to the transmission case (13) is pressed against the cam (43) by the urging force of the spring (45), near the other end of the link support shaft (38). Since the arm (46) is fixed and the damper (47) is connected, and when the link support shaft (38) is rotated, the cam (43) is returned by the action of the damper (47). Forward pedal (30) or reverse pedal (31) During depression released, the roller (44) is returned to the recess center of the cam (43), configured so that each pedal (30, 31) is held by return to the original position,
Furthermore, the work vehicle characterized in that the pedal support shaft (34), the link support shaft (38), and the link mechanism are mounted on the bracket (33) in an assembled state. Hydrostatic continuously variable transmission.   The hydraulic motor (22) changes the rotation of the hydraulic motor (22) to high torque or low torque according to the discharge amount of the hydraulic pump (21) by switching the tilt angle of the internal swash plate in two stages. The discharge amount of the instantaneous hydraulic pump (21) when the internal swash plate of the hydraulic motor (22) is switched is changed by the motor changeover switch provided on the meter panel, and the rotation speed of the output shaft is changed immediately before the motor changeover By adjusting to the rotational speed, the change in vehicle speed before and after the shift becomes small and the shift shock is suppressed. Also, the trunnion shaft (23) is equipped with an electromagnetic brake mechanism, and the cruise control switch together with the motor changeover switch. And the electromagnetic brake mechanism is operated by the cruise control switch, and the hydrostatic continuously variable transmission is provided. The hydrostatic continuously variable transmission for a work vehicle according to claim 1, characterized in that the vehicle speed can be kept constant without continuing to hold the pedal (30, 31) of 19) with a foot. .

Images