JP2002274202A - Hydrostatic continuously variable transmission of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the assembly workability, and to reduce the cost by simplifying a pressure oil piping in mounting an HST on a working vehicle. SOLUTION: A port block 29 is provided on a front part of a transmission case 13, a hydraulic pump 30 is disposed at a substantially center position of an upper part of the front side of the port block 29, a hydraulic motor 31 is disposed on one lower side in the diagonal direction of the hydraulic pump 30, a filter 32 is disposed on the other lower side in the diagonal direction of the hydraulic pump 30, and these are directly fitted to the front side of the port block 29 to constitute the HST 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic continuously variable transmission for a work vehicle, and more particularly to a structure for mounting a hydrostatic continuously variable transmission in a work vehicle such as a tractor or a rice transplanter. It is.

[0002]

2. Description of the Related Art In a relatively small work vehicle, there is known one in which the engine power is shifted by a hydrostatic continuously variable transmission (HST). The HST is configured by combining a variable hydraulic pump driven by engine power and a hydraulic motor driven by the hydraulic pump,
By changing the tilt angle of the hydraulic pump, the rotation of the hydraulic motor is steplessly shifted and output.

Conventionally, a sheet metal frame or a cast case is interposed between a clutch housing and a transmission case, and the HST is housed in the frame or the case.
The partition walls before and after the HST are provided with bearing portions for supporting an input shaft and an output shaft of the HST, a clutch shaft of a PTO clutch, and the like. In addition, piping for charging the HST with pressure oil, and piping such as a clutch port and a clutch lubrication port to the PTO clutch are also connected.

[0004]

In the conventional HST, the pipes to the respective ports are exposed, so that the appearance is deteriorated, and the handling of connecting the pipes is complicated and the assembling workability is poor. In addition, a bearing portion for supporting each shaft is required, which makes the configuration complicated and increases the cost.

Therefore, when the HST is mounted on a work vehicle, technical problems to be solved arise in order to simplify the piping of the pressure oil to improve the workability of assembly and to reduce the cost. The invention aims to solve this problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in order to achieve the above object, and has a variable hydraulic pump 30 driven by the rotational power of an engine 11 and a hydraulic pump 30 driven by the hydraulic pump 30. A continuously variable transmission 20 including a hydraulic motor 31 which is provided at a substantially central position above a port block 29 provided at the front of the transmission case 13. The hydraulic pump 30
, A hydraulic motor 31 is disposed on one obliquely lower side of the hydraulic pump 30, and a filter 32 is disposed on the other obliquely lower side of the hydraulic pump 30. Hydrostatic continuously variable transmission for a work vehicle attached to the front, and port block 2
Reference numeral 9 denotes ports P ₁ and P _{2 of} the charge oil passing through the filter 32, a clutch port P ₃ and a clutch lubrication port P ₄ to a PTO clutch 40 provided in the transmission case 13, and a bearing of the PTO clutch shaft 36. The present invention provides a hydrostatic continuously variable transmission for a working vehicle provided with a part 37.

[0007]

An embodiment of the present invention will be described below 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 a front part of the fuselage, covered with a hood 12, a transmission case 13 is attached to a rear part of the fuselage, and a cabin 14 is
And a driver's seat 15 is provided in the cabin 14. A clutch housing 16 is mounted on a rear portion of the engine 11, and a main clutch 17 is provided inside the clutch housing 16.

The main clutch 17 and the transmission case 1
3 is provided with a hydrostatic stepless transmission (HST) 20. The rotational power of the engine 11 is input to the HST 20 via the main clutch 17, and the speed is continuously changed by the HST 20. It is configured to be transmitted to the transmission case 13 later.

In the transmission case 13, the HST2
The power shifted at 0 is split into the power of the traveling system and the power of the PTO system, and the power of the traveling system is shifted by the gear type transmission 21, and the rear wheels 23 are driven via the rear differential device 22. The front wheels 26 are driven from the front wheel transmission shaft 24 via the front differential device 25. On the other hand, the power of the PTO system is output from a PTO output shaft 27 protruding from the rear surface of the transmission case 13.

As shown in FIGS. 2 to 5, the transmission case 13 includes a front transmission case 13a and a rear transmission case 13b, and a port block 29 described below is provided between the front transmission case 13a and the clutch housing 16. The HST 20 is directly attached to the front surface of the port block 29. The HST 20 is an engine 1
A variable hydraulic pump 30 driven by one rotating power;
A hydraulic motor 31 driven by the hydraulic pump 30;
A filter 32 for filtering the charge oil;
And a hydraulic motor 31 is mounted on one side of the hydraulic pump 30 diagonally below, and a filter 32 is mounted on the other side of the hydraulic pump 30 diagonally below. That is, since the hydraulic motor 31 and the filter 32 are distributed and arranged at the lower left and right positions in front view with the hydraulic pump 30 as the top, each device is compactly arranged and H
The installation space of ST20 can be reduced.

The rotational power of the engine 11 is supplied to the main clutch 17.
When the main clutch 17 is engaged, the rotational power of the engine 11 is input to the hydraulic pump shaft 33 of the HST 20 via the rotating shaft 17 a projecting rearward from the main clutch 17. If the trunnion shaft 34 is rotated by the operation of the operator, the discharge amount of the hydraulic pump 30 is changed, and the rotation speed of the hydraulic motor 31 changes steplessly. The hydraulic pump shaft 33 penetrates through the front and rear of the hydraulic pump 30, and the rear part of the hydraulic pump shaft 33 penetrates through the port block 29 and protrudes into the front transmission case 13a. It is pivoted. The hydraulic motor output shaft 35 extends rearward of the HST 20 through the port block 29, and is pivotally supported by fitting a gear 45 to its rear end.

At the front of the front transmission case 13a, the hydraulic pump shaft 33 and the hydraulic motor output shaft 35 are provided.
A PTO clutch shaft 36 is pivotally mounted in parallel with the PTO clutch shaft 36, a wet multi-plate PTO clutch 40 is provided on the PTO clutch shaft 36, and a bearing portion 3 is provided on the rear surface of the port block 29.
7 is provided to support the front end of the PTO clutch shaft 36.
A gear 42 that is freely rotatable about the PTO clutch shaft 36 is externally fitted to the front of the PTO clutch 40.
1 meshes with this gear 42. The PTO clutch shaft 36 is pivotally mounted on the left and right sides opposite to the hydraulic motor output shaft 35. Assuming that the hydraulic pump shaft 33 is the apex, the hydraulic motor output shaft 35 is pivotally mounted on one lower side thereof. A PTO clutch shaft 36 is pivotally attached to the lower other side to form a triangle.

On the other hand, the front wheel transmission shaft 24, the PTO drive shaft 46, and the traveling drive shaft 47 are pivotally mounted on the rear portion in the front transmission case 13a in parallel with the hydraulic motor output shaft 35 and the PTO clutch shaft 36. The gear 43 fitted to the rear end of the PTO clutch shaft 36 meshes with the gear 44 fitted to the front end of the PTO drive shaft 46, so that the rotational output of the rotary shaft 17a of the main clutch is not shifted, The PTO power output as it is via the PTO clutch 40 is output from the PTO output shaft 27 via the rear PTO transmission 51.

A cylindrical gear 48 is freely and freely rotatably fitted to the PTO drive shaft 46. A gear 49 provided at a tip end of the cylindrical gear 48 meshes with the gear 45, and the traveling system is shifted by the HST 20. After the power is transmitted to the cylindrical gear 48 and is shifted by the gear type transmission 21 provided on the traveling transmission shaft 47, the rear wheel 23 is driven via the rear differential device 22. Further, a shifter gear 52 is fitted to the rear end of the front wheel transmission shaft 24 so as to be slidable back and forth.
A counter gear 53 and a shifter gear 52 which are freely rotatably fitted to the rear end of the drive gear mesh with each other to transmit the rotation of the traveling speed change shaft 47 to the front wheel transmission shaft 24.

Here, the ports P ₁ , P _{2 of} the charge oil passing through the filter 32 are provided in the port block 29.
A PT described later provided in the front transmission case 13a
A clutch port P ₃ and a clutch lubrication port P ₄ are provided to the O-clutch 40, and the PTO clutch valve 39 and the filter 3 provided in the clutch housing 16 are provided.
The hydraulic pump 30, the hydraulic motor 31, the filter 32, and the like are directly attached to the front surface of the port block 29 so that each port such as 2 matches the port of the port block 29, so that piping to each port is exposed. Without this, the appearance is improved, and the work for connecting the pipes is eliminated, so that the assembling workability is improved.

Also, since a bearing 37 is provided on the rear surface of the port block 29 to support the front end of the PTO clutch shaft 36, the front transmission case 1
It is not necessary to separately provide a metal or the like for the PTO clutch shaft 36 in 3a, so that the power transmission configuration in the transmission case 13 can be simplified, and the cost can be reduced by reducing the number of parts.

As shown in FIG. 6, the clutch housing 1
A trunnion shaft 34 and a brake pedal shaft 55 of the HST 20 are protruded from the right side surface of the trunnion shaft 6, and a trunnion arm 38 that rotates integrally with the trunnion shaft 34 is fixed to both upper and lower directions of the trunnion shaft 34. is there. A brake pedal 56 is pivotally mounted on the brake pedal shaft 55, and a pedal arm 5 is mounted on a rotation base of the brake pedal 56.
7, and a distal end of a brake arm 58 provided on a side surface of the rear transmission case 13b and a distal end of a pedal arm 57 are connected by a brake rod 59.

On the other hand, a pin 61 is provided on a bracket 60 fixed to the transmission case, and a rotating plate 63 of a cruise control lever 62 is pivotally mounted on the pin 61.
Then, one end of a control wire 64 is fixed to one side of the rotating plate 63, and the control wire 6
4 is connected to one end of the trunnion arm 38. Further, one end of another control wire 65 is fixed to the other side of the rotating plate 63 (a position symmetrical with respect to the control wire 64 at the pin 61). The end is connected to the other end of the trunnion arm 38. Further, a long hole 66 is formed in the rotation plate 63 along a circumference around the pin 61 so that the rotation of the rotation plate 63 can be stopped by a locking tool such as a stopper screw 67. It is formed.

When the operator rotates the cruise control lever 62 forward (to the right in the figure) from the driver's seat, the rotating plate 6 is rotated about the pin 61.
3 is rotated clockwise in the figure, and while one control wire 64 is pressed, the other control wire 6
5, the trunnion arm 38 is rotated clockwise in the drawing. Accordingly, the trunnion shaft 34 rotates clockwise integrally with the trunnion arm 38, and the HST
When the tilt angle of the hydraulic pump 30 is changed, the hydraulic motor output shaft 35 rotates in the forward direction of the vehicle body, and the rotation of the hydraulic motor output shaft 35 increases according to the amount of rotation of the cruise control lever 62. I do.

On the other hand, when the cruise control lever 62 is rotated rearward (to the left in the figure), the rotating plate 63 rotates counterclockwise around the pin 61, and At the same time that the control wire 64 is pulled, the other control wire 65 is pushed, and the trunnion arm 38 rotates counterclockwise in the figure.
Therefore, the trunnion shaft 34 is
And the tilt angle of the hydraulic pump 30 of the HST 20 is changed, the hydraulic motor output shaft 35 rotates in the reverse direction of the vehicle body, Then, the rotation of the hydraulic motor output shaft 35 increases.

Even when the cruise control lever 62 is rotated in any of the front and rear directions, the rotation posture of the cruise control lever 62 can be stopped by rotating the stopper screw 67 to fix the rotating plate 63. it can. That is, the control wire 6
Since the push and pull of the wheels 4 and 65 are locked and the rotation angles of the trunnion arm 38 and the trunnion shaft 34 are maintained as they are, so-called auto cruise traveling in which the traveling speed of the vehicle body is kept constant.

Here, separately from the control wires 64 and 65, the control wires 68 and 69 are located on the trunnion arm 38 at positions slightly closer to the trunnion shaft 34.
Of the control wire 68,
The other end of 69 is connected to the distal end of the pedal arm 57 via a return tool such as a tension coil spring (not shown). Accordingly, the trunnion arm 38 is pulled by both the control wires 68 and 69, and is biased so that the trunnion shaft 34 always returns to the neutral position. When the turning operation of the cruise control lever 62 is released, the HST 20 is released. Returns to the neutral position. When the brake pedal 56 is depressed during the above-described auto cruise travel, the pedal arm 57 rotates clockwise in the figure to pull both control wires 68 and 69, so that the trunnion arm 38 and the trunnion shaft 34 are pulled.
Is returned to the neutral position. That is, if the brake pedal 56 is depressed during the auto cruise driving, the auto cruise driving is released, so that safety can be ensured.

FIG. 7 shows a detent mechanism 70 for holding the trunnion shaft 34 at the neutral position.
The description of the control wires 68 and 69 connected to the trunnion arm 38 and the pedal arm 57 will be omitted. As described above, one ends of the control wires 64 and 65 are fixed to both ends of the trunnion arm 38,
The other end of each is connected to the rotating plate 63 of the cruise control lever 62.
A protruding piece 71 protrudes toward the front of the vehicle body (to the right in the figure) at the center of the bracket, and a detent mechanism 70 is fixed to a mounting seat 72 of the clutch housing 16 with screws.

In the detent mechanism 70, two round holes 74, 74 and long holes 75, 75 are formed in the surface of the fan-shaped plate 73 with a space between them, and a steel ball is provided on the lower surface side of the round holes 74, 74. 76 and 76 are loaded and pressed against the surface of the plate 73 by a spring (not shown). Accordingly, since the two steel balls 76, 76 sandwich the convex piece 71 on both sides (up and down in the figure), the turning position of the trunnion arm 38 is mechanically restricted, and the trunnion shaft is formed with a simple configuration. 34 is held in the neutral position.

When the cruise control lever 62 is turned in any of the front and rear directions, the control wires 64 and 65 are pushed and pulled to apply a rotating force to the trunnion arm 38, and the convex piece 71 is moved to one of the positions. Overcoming one steel ball 76, the detent is released,
The rotation of the trunnion arm 38 is allowed, and the trunnion shaft 34 rotates forward or backward from the neutral position.
In this detent mechanism 70, the position of the plate can be shifted by loosening the screws 77, 77 of the long holes 75, 75, and the neutral position can be finely adjusted.

In place of the detent mechanism 70,
As shown by a two-dot chain line in the figure, a limit switch 79 is brought into contact with a fixing portion between the control wire 64 or 65 and the trunnion arm 38, and a buzzer or a lamp is operated by turning on or off the limit switch 79. This may be configured to notify the operator of the neutral position.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0028]

As described in detail in the above embodiment, the invention according to claim 1 is characterized in that the hydraulic pump is located at substantially the center of the front upper part of the port block provided at the front of the transmission case, and the hydraulic pump is provided. The hydraulic motor and the filter are directly attached to the diagonally lower one side of the hydraulic pump, and the filter is directly attached to the diagonally lower other side of the hydraulic pump. And the installation space of the hydrostatic stepless transmission can be reduced.

According to the second aspect of the present invention, the port block is provided with each port of the filter and the PTO clutch, and the bearing of the PTO clutch shaft is provided.
The pipes to each port are not exposed, the appearance is improved, and the work for connecting the pipes is eliminated, so that the assembling workability is improved. In addition, there is no need to separately provide metal or the like for the PTO clutch shaft, so that the power transmission configuration in the transmission case can be simplified, and the cost can be reduced by reducing the number of parts.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 is a side view of a tractor.

FIG. 2 is a developed longitudinal sectional side view showing an arrangement configuration of a transmission shaft from a clutch housing to a transmission case.

FIG. 3 is a diagram showing an arrangement of each device such as a hydraulic pump and a hydraulic motor.

FIG. 4 is a diagram showing an arrangement of each shaft such as a hydraulic pump shaft and a motor output shaft.

FIG. 5 is a hydraulic circuit diagram.

FIG. 6 is a right side view of the clutch housing.

FIG. 7 is a view showing a detent mechanism of a trunnion shaft.

[Explanation of symbols]

10 tractor 11 engine 13 transmission case 17 main clutch 20 hydrostatic stepless transmission (HST) 29 port block 30 hydraulic pump 31 hydraulic motor 32 filter _{P 1, P 2, P 3} , P 4 port

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Eiji Tomioka 1-Yakura, Tobe-cho, Iyo-gun, Ehime Pref. AB17 BC01 BC05 BC11 BC16 BD05 EA02 EA06

Claims (2)

[Claims] 1. A hydrostatic continuously variable transmission 20 comprising a variable hydraulic pump 30 driven by the rotational power of an engine 11 and a hydraulic motor 31 driven by the hydraulic pump 30. The hydrostatic continuously variable transmission 20 includes a hydraulic pump 30 disposed substantially at the center of an upper portion of a port block 29 provided at the front of the transmission case 13, and a hydraulic motor 30 disposed diagonally below one side of the hydraulic pump 30. 31 and a filter 32 is disposed diagonally below the other side of the hydraulic pump 30, and each is directly connected to the port block 2.
9. A hydrostatic continuously variable transmission for a work vehicle, wherein the continuously variable transmission is mounted on a front surface of a work vehicle. 2. The port block 29 has ports P ₁ and P ₂ for charge oil passing through the filter 32, a clutch port P ₃ to a PTO clutch 40 provided in the transmission case 13, and a clutch lubrication port P _4. And the PTO
The hydrostatic continuously variable transmission for a work vehicle according to claim 1, further comprising a bearing portion (37) for the clutch shaft (36).