JP2002114051A - Hydrostatic continuously variable transmission for work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an operation feeling and simplify the assembling work by setting the treading strokes of an advance pedal and a reverse pedal equal in an independent two-pedal type hydrostatic continuously variable transmission having the same treading direction for the advance pedal and the reverse pedal. SOLUTION: A pedal support shaft 34 is provided coaxially with the trunnion shaft 23 of the HST, and the advance pedal 30 and the reverse pedal 31 are supported on the pedal support shaft 34. A link support shaft 38 is provided in parallel with the pedal support shaft 34, and the advance pedal 30 and the reverse pedal 31 are connected to the trunnion shaft 23 by the link support shaft 38 and link rods 40 and 42 or the like.

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 working vehicle, and more particularly to a hydrostatic continuously variable transmission for a working vehicle provided with a forward pedal and a reverse pedal separately. is there.

[0002]

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

As means for rotating the trunnion shaft, pedals are fixedly provided on both front and rear sides of the trunnion shaft, and the HST is driven by forward rotation when the front pedal is depressed forward to rotate the trunnion shaft forward. When the rear pedal is depressed backward to reverse the trunnion shaft, the HS
An integrated pedal type configuration in which T is driven in the reverse direction is known. In addition, the forward pedal and the reverse pedal are provided independently on separate shafts, and one or both pedals are connected to the trunnion shaft by a link mechanism, thereby improving the operability by making the depression directions of the forward pedal and the reverse pedal the same. An independent two-pedal configuration is also known.

However, in the conventional independent two-pedal type, the forward pedal and the reverse pedal are provided on separate shafts and are connected to the trunnion shaft by a link mechanism. Therefore, the forward pedal for rotating the trunnion shaft at a predetermined angle is used. The stroke of the reverse pedal was different from the stroke of the reverse pedal, causing an uncomfortable feeling in the pedal operation. In addition, since each member is separately mounted, assembling and adjusting operations are complicated.

Therefore, in an independent two-pedal hydrostatic continuously variable transmission in which the forward and reverse pedals are depressed in the same direction, the depressing strokes of the forward and reverse pedals are made identical to improve the operational feeling. In addition, there arises a technical problem to be solved in order to simplify the assembling work, and an object of the present invention is to solve this problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and is driven by the rotational power of the engine 10 and changes the discharge amount in accordance with the rotation of the trunnion shaft 23. In a work vehicle 10 equipped with a hydrostatic stepless transmission 19 having a variable hydraulic pump 21 and a hydraulic motor 22 driven by the hydraulic pump 21, the same axis as the trunnion shaft 23 is used. The pedal support shaft 34 provided above supports the forward pedal 30 and the reverse pedal 31 so as to be freely depressed in the same direction.
4, a link support shaft 38 is provided in parallel with the rotation of the forward pedal 30 or the reverse pedal 31, and the rotation of the pedal is directly transmitted to the trunnion shaft 23. A hydrostatic continuously variable transmission for a work vehicle connected to reversely rotate the trunnion shaft 23 via a link mechanism formed between link support shafts 38, and the transmission case 1
3, an opening 32 is provided on one side surface, a bracket 33 is attached to the opening 32, and the trunnion shaft 23 is projected,
The present invention provides a hydrostatic continuously variable transmission for a work vehicle in which the bracket 33 is provided with the pedal support shaft 34, the link support shaft 38, and the link mechanism.

[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.

As shown in FIGS. 1 and 2, a clutch housing 16 is mounted at the rear of the engine 11, and a main clutch 17 is provided inside the clutch housing 16. Clutch housing 16 and transmission case 1
An additional transmission case 18 is interposed between the transmission unit 3 and the transmission unit 3, and a hydrostatic continuously variable transmission (HST) 19 is provided in the additional transmission case 18. The rotational power of the engine 11 is input to the HST 19 via the main clutch 17, and after being continuously shifted by the HST 19, the gear type transmission device 20 provided in the transmission case 13 is provided.
It is configured to be transmitted to.

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. When the trunnion shaft 23 is rotated by depressing, the discharge amount of the hydraulic pump 21 is changed, and the rotation speed of the hydraulic motor 22 changes steplessly. The rotation of the hydraulic motor is transmitted to a drive shaft 25 through a reduction gear mechanism 24 provided in front of the HST 19, and after being shifted by a rear gear type transmission 20, power of the traveling system is transmitted through a rear differential device 25. The wheels 26 are driven and the front differential 2
7, the front wheel 28 is driven. 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 transmission case 13.

FIGS. 3 and 4 show a mounting structure of a forward pedal 30 and a reverse pedal 31 for operating the HST 19, wherein an opening 32 is provided on one side surface of the additional transmission case 18, and a bracket 33 is attached to the opening 32. Then, the trunnion shaft 23 is projected outside. 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 is supported by a bracket 33 so that the trunnion shaft 23 and the pedal support shaft 34 can rotate integrally. At the same time, the forward pedal 30 is
Is fixed.

A boss 35 is pivotally attached to the tip of the pedal support shaft 34, and a plate 36 is fixed to the boss 35,
The reverse pedal 31 is fixed to the plate 36. The forward pedal 30 and the reverse pedal 31 are formed so that the depression portions are at the same height, and the reverse pedal 31 rotates about the pedal support shaft 34 together with the boss 35. And the center of rotation of the reverse pedal 31 coincide with each other, and the turning radius of the tread portion becomes the same. An arm 37 is fixed to the base end of the pedal support shaft 34.

Here, a link support shaft 38 is pivotally attached to the bracket 33 in parallel with the pedal support shaft 34, and an arm 39 is fixed to one end of the link support shaft 38. The plate 36 is connected to the link rod 4
Connect at 0. 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 is fixed.
And this arm 41 are connected by a link rod 42. Thus, the forward pedal 3 supported by the pedal support shaft 34
The zero and the reverse pedal 31 are connected to the trunnion shaft 23 by a link mechanism including a link support shaft 38 and link rods 40 and 42 provided in parallel with the pedal support shaft 34.

When the forward pedal 30 is depressed, the pedal support shaft 3 is directly moved by the forward pedal 30.
4 rotates and the trunnion shaft 2 is integrated with the pedal support shaft 34.
3 rotates in the direction of arrow F, and 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, and the link rod 40 is pulled, so that the link support shaft 38 is rotated in the opposite direction to the pedal support shaft 34. Accordingly, the link rod 42 is pushed, and the pedal support shaft 34 rotates in the direction of arrow R, and the trunnion shaft 23 also rotates in the same direction integrally with the pedal support shaft 34, and the HST 19 is driven by the reverse rotation. .

In the vicinity of the other end of the link support shaft 38, a cam 43 having a V-shaped recess is fixed, and a roller 44 pivotally attached to the transmission case 13 is biased by a spring 45 to form the cam 43. 43. Further, an arm 46 is fixed near one end of the link support shaft 38 to
7 is connected, and when the link support shaft 38 rotates, the swing of the cam 43 is returned by the action of the damper 47. Therefore, when the depression of the forward pedal 30 or the reverse pedal 31 is released,
The roller 44 returns to the center of the concave portion of the cam 43, and the pedals 30, 31 return to their original positions and are held.

As described above, the center of rotation of the forward pedal 30 and the center of rotation of the reverse pedal 31 coincide with each other, and the radius of rotation of the depression portion is the same.
0 and the depression stroke of the reverse pedal 31 are the same, and there is no uncomfortable feeling in pedal operation. Also,
Since the pedal support shaft 34, the link support shaft 38, and the link mechanism are mounted on the bracket 33 in an assembled state, the assembling work to the transmission case 13 is extremely easy.

Next, the 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, and switches the tilt angle of the internal swash plate of the hydraulic motor 22 in two stages. The hydraulic pump 2
The rotation of the hydraulic motor 22 can be changed to high torque or low torque in accordance with the discharge amount of (1). Conventionally, the shift shock was large because the solenoid valve was switched automatically or manually. However, the hydraulic pump was switched at the moment when the internal swash plate of the hydraulic motor 22 was switched by the motor switch (not shown) provided on the meter panel. By changing the discharge amount of the output shaft 21 and adjusting the rotation speed of the output shaft to the rotation speed immediately before the motor switching, the change in vehicle speed before and after the shift is small, and the shift shock can be suppressed.

Further, an electromagnetic brake mechanism (not shown) is mounted on the trunnion shaft 23, and a cruise control switch is provided together with the meter changeover switch, and the electromagnetic brake mechanism is operated by the cruise control switch. In this case, the running speed of the vehicle can be kept constant without holding the HST pedal with the foot.

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.

[0019]

According to the present invention, 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 this pedal support shaft has a forward pedal and a reverse drive. By supporting the pedals, the center of rotation of the forward pedal and the center of rotation of the reverse pedal coincide, and the depression strokes of both pedals are the same, so that there is no uncomfortable feeling in pedal operation.

According to the second aspect of the present invention, the pedal support shaft, the link support shaft, and the link mechanism are mounted on the bracket provided on one side surface of the transmission case in an assembled state. It becomes very easy.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 shows an embodiment of the present invention and is a side view of a tractor.

FIG. 2 is a developed longitudinal sectional side view showing the configuration of an HST and a transmission case.

FIG. 3 is a side view showing a mounting structure of a forward pedal and a reverse pedal.

FIG. 4 is a partially cutaway front view showing a mounting structure of a forward pedal and a reverse pedal.

[Explanation of symbols]

 Reference Signs List 10 Tractor 11 Engine 13 Transmission case 19 Hydrostatic stepless 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

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05G 1/14 G05G 1/14 E 11/00 11/00 (72) Inventor Yuji Yoshizawa Tobe, Iyo-gun, Ehime 1 Fuku term (reference) 3D040 AA01 AB04 AC15 AC24 AC28 AC41 AC50 3J067 AA11 AC42 BA32 DA02 DA72 EA84 FB61 FB81 GA14 3J070 AA32 BA11 BA32 BA81 CB01 CC02 CC07 DA24 EA21

Claims (2)

[Claims] 1. Driven by the rotational power of an engine 10,
In addition, work in which a hydrostatic continuously variable transmission 19 including a variable hydraulic pump 21 that changes the discharge amount in accordance with the rotation of the trunnion shaft 23 and a hydraulic motor 22 driven by the hydraulic pump 21 is mounted. In the vehicle 10, the forward pedal 30 and the reverse pedal 31 are supported on a pedal support shaft 34 provided on the same axis as the trunnion shaft 23 so as to be able to be depressed in the same direction. A link support shaft 38 is provided, and the rotation of one of the forward pedal 30 and the reverse pedal 31 is directly transmitted to the trunnion shaft 23, and the rotation of the other pedal is depressed to the link support shaft 38. Trunnion shaft 23 via a link mechanism configured between
A hydrostatic continuously variable transmission for a work vehicle, wherein the transmission is connected in a reverse direction. 2. An opening 32 is provided on one side surface of the transmission case 13, a bracket 33 is attached to the opening 32, and the trunnion shaft 23 is protruded.
The hydrostatic continuously variable transmission for a work vehicle according to claim 1, wherein the pedal support shaft (34), the link support shaft (38), and the link mechanism are mounted on the vehicle.