JPH04306138A - Braking operation structure for work vehicle - Google Patents

Abstract

PURPOSE:To constitute a structure, for operating a rock mechanism to the retention release side when both brake pedals stepped in operation, in such a one for right and left side brakes are operated, which hardly makes inadequate operation, and has reliability and durability; in the braking operation structure of a working vehicle which is provided with a rock mechanism capable of making, in an arbitrary position, retaining and retention releasing operation of a continuously variable transmission position for running energized to the neutral stopping position side, and provided with a pair of side brakes capable of independently braking each of right and left wheels for running. CONSTITUTION:A pair of linking members 23 capable of free rocking around axial cores P2, P3 being approximately at right angles to the direction of stepping in operation of the brake pedals 20, 21; are attached to brake pedals 20, 21 respectively; so as to pivot fore end portions of the pair of linking members 23 in connection to each other. An operating member 38 is arranged on the passing locus of the fore end portions of the linking members 23 when the pair of brake pedals 20, 21 are operated all at once. When the pair of brake pedals 20, 21 are stepped in operation simultaneously, the operating member 38 is pushed in operation by the fore end portions of the linking members 23, and the rocking mechanism of a continuously variable transmission device is operated to the retention release side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake operation structure for a working vehicle equipped with a continuously variable transmission for driving.

0002

[Prior Art] An example of the above-mentioned work vehicle is the one disclosed in Japanese Patent Application Laid-Open No.
It is disclosed in the publication No.-190553. The continuously variable transmission device (1 in Figure 1 of the above-mentioned publication) for driving this work vehicle is energized to the neutral stop position (N in Figure 1 of the above-mentioned publication), and the gear change operation is performed using the speed change pedal. It is configured. or,
A locking mechanism that allows the continuously variable transmission to be held in any position (
15) in FIG. 2 of the above-mentioned publication, and is configured so that the continuously variable transmission device can be held at a desired position during work travel at a constant speed. Furthermore, this work vehicle is equipped with a pair of handbrakes that can brake the left and right wheels independently, and a pair of brake pedals for the handbrakes (23a and 23b in FIG. 2 of the above publication). .

[0003] When one wheel is braked while driving with the continuously variable transmission held at a desired position by the above-mentioned locking mechanism and the vehicle turns, the method shown in FIG. 2 of the above publication is used.
As shown in FIG. 2, even if one brake pedal is depressed, the linking member (26 in FIG. 2 of the above-mentioned publication) is only tilted, and the locking mechanism is not operated to the holding release side. Conversely, when both brake pedals are pressed simultaneously, such as when stopping the aircraft, the linking member moves as a whole, and the locking mechanism is operated to the holding release side.

0004

[Problem to be Solved by the Invention] As described above, the locking mechanism for a continuously variable transmission is controlled depending on the state of depression of a pair of brake pedals (whether only one is depressed or both are depressed simultaneously). In the case of a configuration in which the lock mechanism is operated toward the holding release side, in the conventional structure described above, the linking member for operating the lock mechanism toward the holding release side (26 in FIG. 2 of the above publication) and the brake pedal are connected to the elongated hole (see above) 26a, 26 in Figure 2
b, 26c), the structure is such that the locking mechanism can be operated to the holding release side by utilizing the flexibility of the elongated hole.

[0005] In the case of a structure that uses many long holes for flexibility, the sum of mechanical errors occurring in the long holes is relatively large, so there is a risk of malfunction after long-term use. be. An object of the present invention is to configure a structure for operating a locking mechanism for a continuously variable transmission to the holding release side depending on the depression operation state of a pair of brake pedals as described above, so that it operates reliably with fewer malfunctions. There is.

[0006]

[Means for Solving the Problems] As described above, the present invention is characterized by a continuously variable transmission for traveling that is biased toward a neutral stop position, and a continuously variable transmission that maintains the shift position of the continuously variable transmission at an arbitrary position. A braking operation structure for a work vehicle equipped with a locking mechanism that can be freely held and released, and a pair of side brakes that can independently brake each of the right and left running wheels, which is configured as follows. be. In other words, a pair of brake pedals for operating the handbrake are placed close to each other on the left and right,
A pair of link members that can swing freely around an axis substantially perpendicular to the direction in which the brake pedal is depressed is attached to each of the brake pedals, and the tips of the pair of link members are pivotally connected to each other, and the pair of brake pedals The operating member is placed on the trajectory of the tip of the link member when the brake pedals are pressed simultaneously, and when the pair of brake pedals are simultaneously depressed, the operating member is pushed by the tip of the link member, and this operating member The operating member and the locking mechanism are linked together so that the locking mechanism is operated to the holding release side.

[0007]

[Operation] With the above-described structure, when the vehicle is traveling with the continuously variable transmission device held at a certain shift position by the locking mechanism, the brake pedal 20 on one side is pressed as shown in FIGS. Suppose you press and operate. When only one brake pedal 20 is depressed in this way, as shown in FIG. Axis P3 remains in that position. As a result, the tips of the left and right link members 23 move diagonally downward and to the right in the paper from the positions shown in FIG. 1, and the operating member 38 is not pushed by the tips of the link members 23. In other words, the locking mechanism is not operated to the holding release side,
This maintains the continuously variable transmission in its held state. On the other hand, when stopping, etc., the left and right brake pedals 20, 2
Suppose that both of 1 are pressed at the same time. In this case, from the state of FIG. 1, the left and right link members 23 and the axis P2, P3
moves downward in the drawing, and the tips of the left and right link members 23 also move downward in the drawing from the state shown in FIG. 1, and the operating member 38 is pressed and operated. As a result, the locking mechanism is operated to the holding release side.

In the structure of the present invention described above, instead of using the conventional structure in which the locking mechanism is operated to the holding release side by utilizing the flexibility of the elongated hole, three points of the link member (see FIG. 1) are used.
axes P2, P3 and the tip of the link member 23)
Since it has a pivot structure, it has a structure that does not have any looseness due to so-called flexibility. As a result, mechanical errors caused by backlash and the like are relatively small, so there is little risk of malfunction even after long-term use.

[0009]

[Effects of the Invention] As described above, in a work vehicle equipped with a structure in which the locking mechanism for a continuously variable transmission is operated to the holding/releasing side depending on the state of depression of a pair of brake pedals, the problem occurs even after long-term use. It was possible to create a structure in which mechanical errors are small, so that it operates reliably with fewer malfunctions, and the reliability and durability of this structure can be improved.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. As shown in Figure 9, the aircraft is supported by front wheels 1 and rear wheels 2 (corresponding to running wheels), and has an engine 3 at the front, a control section 4 at the center of the aircraft, and a mission case 5 at the rear of the aircraft. An agricultural tractor is an example of a working vehicle.

As shown in FIGS. 4 and 9, a hydrostatic continuously variable transmission 6 (hereinafter abbreviated as HST) (continuously variable transmission for traveling) is installed in the mission case 5 at the rear of the aircraft. ), and then this HST
The operation structure of No. 6 will be explained. As shown in Figure 8, HS
An operating shaft 7 protrudes laterally from the swash plate (not shown) of T6, and a first operating plate 8 and a second operating plate 16 are fixed to this operating shaft 7, and a forward speed change pedal 9 and a reverse speed change pedal 9 are connected to each other. An operating rod 11 equipped with a speed change pedal 10 is fixed to a second operating plate 16.

As shown in FIG. 8, a dogleg-shaped operating arm 12 is swingably supported around the horizontal axis P1 of the mission case 5, and a roller 14 at one end of the operating arm 12
is placed against the lower surface of the first operation plate 8. and,
The operating arm 12 is biased upward by the spring 15, and the biasing force of the spring 15 biases the first operating plate 8 and the like to the neutral stop position.

This agricultural tractor is equipped with a speed change lever 13 in addition to the forward and reverse speed change pedals 9 and 10. Next, the linkage structure between the speed change lever 13 and the operating shaft 7 of the HST 6 will be described. As shown in FIGS. 4 and 5, a support shaft 27 having an oval-shaped cross section with a partially cut out outer surface is rotatably supported on a fixed support plate 26 at the rear of the fuselage. Lever 13 is fixed. A friction plate 29 is externally fitted onto the support shaft 27, and a cylindrical member 31 presses the friction plate 29 to the right in the drawing by a spring 30, thereby frictionally holding the support shaft 27 and the speed change lever 13. As described above, the friction holding type locking mechanism 32 is constituted by the friction plate 29, the spring 30, the cylindrical member 31, and the like. As shown in FIGS. 5 and 7, the cylindrical member 31 is provided with four sets of protrusions 31a, and the support plate 26 is provided with four sets of openings 26a. As a result, the protrusion 31a
This presses the friction plate 29, and prevents the cylindrical member 31 from rotating due to the engagement between the protrusion 31a and the aperture 26a.

An operating arm 33 is fitted on the opposite side of the support shaft 27 so as to be relatively rotatable, and as shown in FIGS. A full wire 34 is installed. On the contrary,
The engagement member 35 is swingably attached around the axis P4 of the support shaft 27, and a helical spring 36 is attached that biases the engagement member 35 in a counterclockwise direction in the drawing in FIG. A linking rod 37 is attached to the arm portion 35a of the engaging member 35, and the linking rod 37 extends to near the upper end of the gear shift lever 13 and is swingable around the axis P5 of the gear shift lever 13. A link rod 37 is attached to the operating member 39. As shown in FIGS. 5 and 6, a guide member 40 is fixed near the upper end of the shift lever 13 along the operating direction of the shift lever 13, and the operating member 39 is moved to the guide member by the biasing force of the helical spring 36. It is assigned to 40.

The state shown in FIGS. 5 and 6 is that the gear shift lever 13
This is a state in which the vehicle is being operated to the neutral position N. This shift lever 13 can only be operated within the range from the neutral position N to the forward side F, and cannot be operated to the reverse side. And the support shaft 27
A spring 18 that biases the support shaft 27 and the shift lever 13 toward the neutral position N is attached to the arm portion 17 fixed to the arm portion 17 . In this case, the engaging member 35 is connected to the operating arm 33.
Forward and reverse gear change pedals 9,
10, the HST 6 can be freely shifted to the forward and reverse sides.

From the state shown in FIGS. 5 and 6, shift lever 1
3 to the forward side F, the guiding action of the guide member 40 pushes the operating member 39 to the right in the plane of the drawing in FIG. The operating arm 33 is pushed and swung by the engaging member 35, and the HST 6 is operated to the forward high speed side. In this case, even if you release your hand from the shift lever 13 at the desired shift position, the shift lever 13 will be held at that shift position by the holding action of the locking mechanism 32, and the aircraft will remain in the shift position of the shift lever 13. It moves forward at a corresponding constant speed. In this case, if the forward speed change pedal 9 is depressed and operated, the engagement member 35 of the operating arm 33 is released and the speed can be increased to above the above-mentioned constant speed, and when the forward speed change pedal 9 is released, The operating arm 33 comes into contact with the engaging member 35 and returns to the aforementioned constant speed.

With the above structure, when the shift lever 13 is held at a predetermined position on the forward side F, the shift lever 13 can be returned directly to the neutral position N, or the reverse shift pedal 10 can be depressed to push the full wire. When the gear shift lever 13 is returned to the neutral position N via the lever 34, the engaging member 35 is automatically separated from the operating arm 33 due to the biasing force of the helical spring 36. In other words, the gear shift lever 13 and HST6
The link will be automatically canceled.

Next, the relationship between the running handbrake 19 and the lock mechanism 32 shown in FIG. 5 will be explained. As shown in FIG. 4, a pair of side brakes 19 are provided that can brake the left and right rear wheels 2 independently. On the other hand, Figure 3
As shown in FIG. 1, a pair of left and right brake pedals 20 and 21 are supported side by side and swingably around the horizontal axis P6 of the control unit 4, and the left and right side brakes 19 and the left and right brake pedals 20 and 21 are interlocked and connected by linking rods 22, respectively. Also, the left and right brake pedals 20,2
A spring 28 is attached that biases 1 toward the brake release side.

As shown in FIGS. 1 and 3, a pair of links are swingable around axes P2 and P3 that are substantially orthogonal to the direction in which the left and right brake pedals 20 and 21 are depressed (up and down in the paper). The member 23 is the left and right brake pedals 20, 2.
1 is attached to each of the lower surfaces. The tips of the left and right link members 23 are pivotally connected by a pin 24, and a roller 25 is attached to this pin 24. An operating member 3 is provided below the brake pedals 20, 21.
8 is supported so as to be able to swing downward from the position shown in FIG. 3 around the horizontal axis P7, and is provided with a helical spring 41 that urges the operating member 38 upward. An operating portion 38a having a chevron-shaped shape when viewed from the front is fixed to the tip of the operating member 38, and as shown in FIG. 1, when the left and right brake pedals 20, 21 are not depressed, the link member The roller 25 at the tip of the roller 23 is positioned at the upper end of the chevron shape of the operating section 38a.

On the other hand, as shown in FIGS. 4 and 5,
The hydraulic oil from the charge pump 42 of the HST 6 is transferred to the switching valve 4.
3, the oil is supplied to the oil chamber 31b inside the cylindrical member 31 of the lock mechanism 32. This switching valve 43 is biased by a spring 43a toward a first position 43A for removing hydraulic oil from the oil chamber 31b, and normally the gear shift lever 13 is held by the action of the spring 30 shown in FIG. . Then, as shown in FIGS. 3 and 4, the operating member 3
8 and the switching valve 43 are interlocked and connected by a linkage mechanism 44.

With the above structure, when the vehicle is traveling with the gear shift lever 13 held at a predetermined position on the forward side F by the locking mechanism 32, the brake pedal 20 on one side is depressed and operated, for example, when making a small turn. Suppose we did. When only one brake pedal 20 is depressed in this way, the link member 23 on the left side of the page
The link member 23 and the axis P3 on the right side of the page remain at the same position while the axis P2 and the axis P2 move downward in the page. As a result, the roller 2 at the tip of the left and right link members 23
5 moves from the position shown in FIG. 1 along the upper right surface of the operating portion 38a in the drawing to the diagonally lower right in the drawing, and the operating member 38 is not pushed downward. In other words, the lock mechanism 32 in FIG. 5 is not operated to the holding release side, and the gear shift lever 1
3 is maintained.

On the other hand, assume that both the left and right brake pedals 20 and 21 are depressed simultaneously, such as when the vehicle is stopped. In this case, from the state shown in Fig. 1, the left and right link members 2
3 and axes P2 and P3 move downward, and the roller 25 also moves downward from the state shown in FIG. 1, pushing the operating member 38 downward. As a result, the switching valve 43 in FIG. 4 is moved to the second position 43B by the action of the linkage mechanism 44.
, the hydraulic oil from the charge pump 42 is supplied to the oil chamber 31b inside the cylindrical member 31 of the lock mechanism 32. Then, the cylindrical member 31 is slid to the left in FIG. 5, and the holding action of the locking mechanism 32 disappears. Thereafter, the shift lever 13 is returned to the neutral position N by the urging force of the spring 18, and the spring 1 shown in FIG.
The HST 6 is returned to the neutral stop position by the urging force of 5.

Further, as shown in FIG. 2, the operating portion 38a is configured to have a relatively wide width from side to side. This means that, for example, one brake pedal 20 is
When the other brake pedal 21 is started to be operated after a short delay after the first pedal is pressed, the roller 25 may move downward with a slight deviation to the right or left from the position shown in FIG. This is to ensure that the roller 25 pushes the operation section 38a downward even when the operation is performed. In the above embodiments, a belt-type continuously variable transmission device may be provided in place of the HST 6.

[0024]Although reference numerals are written in the claims for convenience of comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

[Figure 1] Front view of the left and right brake pedals and the vicinity of the link members

[Fig. 2] A front view of the vicinity of the link member when the brake pedal on the left side of the page is depressed from the state shown in Fig. 1.

[Figure 3]
Side view of the left and right brake pedals and link members

[Fig. 4] A schematic diagram showing the interlocking state of the hydrostatic continuously variable transmission, forward and reverse speed change pedals, speed change lever, lock mechanism, and left and right brake pedals.

[Fig. 5] Vertical rear view of the vicinity of the gear shift lever and lock mechanism

[
Figure 6: Plan view of the vicinity of the gear shift lever and guide member

[Figure 7]
Vertical side view of the cylindrical member and friction plate of the locking mechanism in FIG. 5

[Figure 8] Side view of the vicinity of the forward and reverse gear shift pedals

[Figure 9] Overall side view of agricultural tractor

[Explanation of symbols]

2. Wheels for traveling 6 Continuously variable transmission 19　　　　　　　Hand brake 20, 21 Brake pedal 23 Link member 32 Lock mechanism 38 Operation member P2, P3 Axis core

Claims (1)

[Claims] Claim 1: A continuously variable transmission (6) for traveling that is biased toward a neutral stop position, and a lock that can hold and release the shift position of the continuously variable transmission (6) at any position. A brake operation structure for a work vehicle, comprising a mechanism (32) and a pair of side brakes (19) capable of independently braking each of the right and left running wheels (2), wherein the side brakes (19) ) A pair of brake pedals (20) for operation, (
21) are arranged close to each other on the left and right, and the axis (
P2), (P3) A pair of link members (
23) is attached to each of the brake pedals (20) and (21), and the tips of the pair of link members (23) are pivotally connected to each other, and the pair of brake pedals (23) are attached to each of the brake pedals (20) and (21).
20) and (21) at the same time, the operating member (
38) and said pair of brake pedals (20).
, (21) at the same time, the link member (2
The operating member (38) is pushed by the tip of the locking mechanism (32).
) is operated to the holding release side.
) and a locking mechanism (32) are linked to each other.