JPH01182171A - Steering brake structure for working vehicle - Google Patents

Abstract

PURPOSE:To increase a brake force through increase of a discharge oil pressure at and following the middle of a stroke, by a method wherein as an artificial control force on a manual operation lever is increased, a press force on the valve seat of the throttle valve of a variable relief valve is increased. CONSTITUTION:A valve seat 22 is situated in an oil passage A of a valve body 21. A poppet type throttle valve 23 making contact with the valve seat 22 is provided. Through application of throttling on discharge oil, introduced through an input port (a) and fed from a control cylinder, by means of the poppet type throttle valve 23, a discharge pressure through an output port (b) is regulatabele. With a manual control arm 13 slid to a brake engaging position, the poppet type throttle valve 23 is brought into a state to make contact with the valve seat 22. With a control force further exerted, the control arm 13 is bent, the press force of the poppet type throttle valve 22 on the valve seat is increased, a discharge oil pressure is increased to increase a brake force.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a system in which the steering braking force increases as the exhaust pressure from the middle of the stroke of each operating cylinder that operates a pair of left and right steering brakes on/off is increased. The present invention relates to a steering brake structure for a working vehicle in which a manual operation lever is linked via a mechanical linkage mechanism to a variable relief valve that adjusts the exhaust pressure.

[Conventional technology]

In the steering brake structure of this type of work vehicle, in order to configure the variable relief valve, conventionally, a spring that presses the throttle valve against the valve seat is connected between a spring that presses the throttle valve against the valve seat and a presser pin that transmits the operation of the manual operation lever to the throttle valve. The operating amount of the holding pin increases as the operating amount of the manual operating lever increases, thereby increasing the spring and increasing the pressing force against the valve seat of the throttle valve. The exhaust pressure from the middle of the stroke was increased. (For example, Japanese Patent Application Laid-Open No. 60-261783).

[Problem to be solved by the invention]

Since the exhaust pressure, or brake pressure, is created using a spring force, in order to obtain a large brake pressure, a large expansion and contraction of the spring is required, which is inevitably connected to this variable relief pulp by a mechanical linkage mechanism. It was necessary to set the amount of operation of the manual operation lever to a large value.

Therefore, the amount of operation of the manual operation lever becomes large, and there is room for improvement in terms of operability.

An object of the present invention is to provide a variable relief pulp that has a wheel wheel and is modified so that the amount of operation on a manual operation lever can be reduced.

[Means to solve the problem]

A characteristic configuration according to the present invention is such that as the manual operation force applied to the manual operation lever increases, the pressing force of the variable relief pulp against the valve seat of the throttle valve increases, thereby increasing the exhaust pressure from the middle of the stroke of the operation cylinder. Its functions and effects are as follows.

[For production]

For example, as shown in FIG.
2) (other configurations can be considered in which the throttle valve (23) is not pressed against the valve seat (22) by a spring).
23) in contact with the valve seat (22), the greater the operating force applied to the manual operation lever (11), the greater the control arm for the holding pin (25) constituting the mechanical linkage F# (14). 13) and the manual operation lever (11) are bent to increase the pressing force of the throttle valve (23) against the valve seat (22).

Therefore, by increasing the pressing force of the throttle valve (23) against the valve seat (23), the operating cylinder (8^)
, The exhaust oil pressure from (8B) can be increased, and the steering braking force can be increased.

〔Effect of the invention〕

Conventionally, the stroke of the manual operation lever was increased to increase the pressure force on the valve seat of the throttle valve, but now the pressure force on the valve seat of the throttle valve can be varied by varying the operating force on the manual operation lever. With this configuration, it is possible to increase the pressing force against the valve seat of the throttle valve without increasing the amount of operation of the manual operation lever, thereby making it possible to improve operability by reducing the amount of operation.

In addition, since the throttle valve and the manual operation lever are not linked via a spring as in the past, the pressure applied to the throttle valve is more directly reflected on the manual operation lever, and the brake force and manual operation lever are There is a more accurate correspondence between the operating force and the operating feel, which improves the operating feel.

〔Example〕

A parking brake structure used in a Kosibain as an example of a work vehicle will be described.

As shown in Figure 4, a pair of left and right crawler traveling devices (1
), drive case (2) for (1), (2)
A pair of left and right steering clutches and brakes (4A) and (4B) are installed in the transmission case (3) that supports the
This steering clutch/brake (4A), (4B)
It consists of a pawl clutch type steering clutch and a multi-disc type steering brake that is operated by the clutch sleeve of the steering clutch. Then, the shift fork (5) that acts on the clutch sleeve to turn on and off the steering clutch/brake (4^) + (4B) can be attached to the operating shaft (6) while being engaged with the clutch sleeve. be. Operating arms (7A) and (7B) are fixed to the outwardly protruding end of the mission case (3) of the operating shaft (6) for the left and right steering flank brakes (4A) and (4B) so as to be able to rotate together. Left and right operation cylinder (8A), which will be described later,
(8B) is power-driven operated. That is, the operation arm (7A).

(7B) Move the piston rod upwards to the operating arm (
Left and right operation cylinder (8A) in contact with 7^) and (7B)
.

(8B) and this left/right operation cylinder (8B).
^), an electromagnetic control valve (9) that selectively supplies hydraulic oil to (8B), and a left/right operation cylinder (8A).

A variable relief pulp (10) is provided in the drain oil confluence path from the middle of the stroke of (8B), so that the steering clutches and brakes (4a) and (4B) can be operated with power.

The steering clutch/brake (4A), (4B)
A single manual operation lever (11) is provided for the control lever (11), and the electromagnetic control valve (9 ) to supply oil to the operating cylinder (8A or 8B) on the swinging direction side of the operating lever (11).

Then, the piston rod extends, the operating arm (7^ or 7B) on the steering direction side is rotated, and the steering clutch is disengaged. When the reproducing lever (11) is further swung from the clutch disengaged position, the variable relief pulp (1
0) is effective, the exhaust pressure can be varied, and the higher the exhaust pressure is, the further the piston rod is extended, increasing the steering braking force, and once the variable relief pulp (10) is completely closed. , can maximize braking force.

The swing operating arm (13) for the variable relief valve (10) and the manual operating lever (11) are interlocked and connected by a release wire (14) serving as a mechanical linkage mechanism, and the operating force for the manual operating lever (11) is controlled. The squeezing force of the variable relief pulp (10) is adjusted. In other words, the swinging left and right interlocking arms (29A) and (29B) do not cross each other near the manual operation lever (11).
), the outer end is connected to the left interlocking arm (29A), and the inner end is connected to the right interlocking arm (29B), so that variable relief can be achieved even when the manual operation lever (11) is swung in either the left or right direction. The squeezing force of the pulp (10) is increased.

As shown in FIG. 2, the outer end (15a) of the release wire (15) is connected to one end of the left operating arm (7A) which is rotatably fitted to the operating shaft (6), and the outer end (15a) of the release wire (15) is aligned with the horizontal axis (Y). At the same time, the inner end (15b) of the inner wire extending from the outer end (15a) is connected to one end of the right operating arm (7B) through a long hole. Connected by pins. On the other hand, the other end side outer end (15C) of this release wire (15) is fixed to a support frame (18) to which a parking pedal (17) as a single human operating tool is attached, and this outer end The inner end (15d) of the inner wire extending from (15c) is fixedly attached to a swing arm (19) that rotates together with the parking pedal (17). Therefore, when this parking pedal (17) is depressed and locked and fixed by the locking member (20), the inner wire is pulled and the outer wire changes its posture, and as shown in the figure, the operation arms (7A) and (7B) swing toward each other. Therefore, the left and right steering brakes are engaged,
The parking brake will be activated.

Next, the structure of the variable relief valve (10) will be explained. As shown in Fig. 1, a valve seat (22) is installed in the oil passage (A) of the pulp body (21), and a poppet type throttle valve (23) is in contact with the valve seat (22).
is provided, and this poppet type throttle valve (23) closes the entrance boat (
The exhaust oil from the operating cylinders (8A) and (8B) introduced in step a) is throttled to adjust the oil pressure discharged from the outlet boat (b).

A plug block (24) is screwed and fixed to the back side of the poppet type throttle valve (23).
In 4), the poppet type throttle valve (23) is pressed against the valve seat (22) by a presser pin (25) that is slidably supported, and the tip of the presser pin (25) and the poppet type throttle valve are pressed together. (
23) and a spacer (26) is interposed therebetween. Further, a pin head (27) is fixed to the tip of the holding pin (25) that protrudes from the plug block (24), and a spring ( 28) is interposed, and the holding pin (25) is urged in a direction away from the poppet type throttle valve (23) by this spring (28), and the swing operation arm (28) which acts on the pin head (27) 13) in a direction approaching the poppet type throttle valve (23).

From the above configuration, when the manual operation lever (11) is swung to the brake position, the poppet throttle valve (23)
is almost in contact with the valve seat (22), and when further operating force is applied from this state, the holding pin (25)
Since the swing operating arm (13) and the manual operating lever (11) are at their sliding limit, the swing operating arm (13) and the manual operating lever (11) are bent, and the pressing force against the valve seat of the poppet type throttle valve (23) increases, and the operating cylinder ( The exhaust pressure from 8A) and (8B) increases, leading to an increase in brake force.

[Another example]

■ The structure of the variable relief valve (10) is that the pope 7 is directly connected to the holding pin (25) without using the spacer (26).
) type throttle valve (23) may be adopted, in which the pressing force of the poppet type throttle valve (23) against the valve seat (22) is not a spring force but only the operating force on the manual operation lever (11). Any configuration that can be varied is sufficient.

- The mechanical interlocking mechanism (14) may be a link mechanism, and is not limited to a wire.

■ The above embodiment may be applied to other working vehicles such as agricultural machinery and construction machinery other than combines.

(2) Although the above embodiment has been explained using a steering clutch/brake, it can also be applied to one having only a steering brake.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the steering brake structure for a working vehicle according to the present invention, FIG. 1 is a sectional view showing the internal structure of a variable relief valve, FIG. 2 is a front view showing the parking brake structure, and FIG.
The figure is a side view showing the operating structure of the parking brake and the steering brake, and FIG. 4 is a hydraulic configuration diagram showing the operating structure of the steering brake. (4a), (4B)...Steering brake,
(8A), (8B)--...Operating cylinder, (
lO)...Variable relief valve, (11)...
...Manual operation lever, (22) ...Valve seat,
(23)... Throttle valve, (14)... Mechanical linkage mechanism.

Claims (1)

[Claims] The steering brake force increases as the exhaust pressure from the middle of the stroke of the respective operation cylinders (8A) and (8B) that operate the left and right pair of steering brakes (4A) and (4B) on and off is increased. A steering brake structure for a work vehicle in which a manual operating lever (11) is linked to a variable relief valve (10) for adjusting exhaust pressure via a mechanical linkage mechanism (14), the manual operating lever The larger the manual operating force for (11), the greater the pressing force against the valve seat (22) of the throttle valve (23) in the variable relief valve (10). A steering brake structure for a work vehicle configured to increase the exhaust pressure of the vehicle.