JP2598037Y2 - Vehicle speed control device for hydrostatic vehicles - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention relates to a hydrostatic drive vehicle (hereinafter referred to as HS) used for construction vehicles such as a wheel loader.
The present invention relates to a vehicle speed control device of a T car (abbreviated as a hydrostatic transmission car).

[0002]

2. Description of the Related Art FIG. 6 shows an external side view of a wheel loader equipped with a snow removing work machine. In the figure, A is a wheel loader main body, and B is a snow removing work machine. FIG. 7 shows a hydraulic circuit diagram of a conventional HST vehicle. In the figure, oil from a hydraulic oil tank 1 is converted into high-pressure oil by a main piston pump 2 and enters a piston motor 13 to drive a power transmission device 20. By operating the forward / backward switching valve 8 and the inching valve 9 to control the servo cylinder 3, the forward / backward shuttle valve 15, the servo valve 16 and the servo cylinder 17, the amount of oil discharged from the main piston pump 2 and the piston motor 13 And the rotational driving force by the hydraulic pressure. 4 is a charge pump for replenishing leaked oil, 6 is a speed relayed valve, 7 is a high pressure cutoff valve, 10 is a high pressure relief valve, 1
Reference numeral 1 denotes a low-pressure relief valve, but since these devices are not directly related to the present invention, description thereof will be omitted.

In a conventional HST vehicle, a vehicle speed is controlled by depressing a brake pedal (indicated by reference numeral 21 in FIG. 2 described later) connected to the inching valve 9 shown in FIG.

[0004]

In the above-mentioned conventional hydraulic circuit device for an HST vehicle, a constant speed is maintained in the case of a vehicle equipped with a snow removing work machine or a vehicle equipped with a road cleaning work machine which operates at a constant speed for a long time. For this reason, the brake pedal is often depressed, and the driver is tired. At the same time, it is difficult to fine-tune the speed in a low speed range. There is also a problem that the brake lamp is turned on even when the brake pedal is depressed for maintaining a constant speed.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a manual inching valve provided in a hydraulic circuit in parallel with an inching valve operated by a foot pedal by a brake pedal. By mounting a disc spring on the rotating shaft of the manual operating lever, the valve can be operated by a manual operating lever that can be fixed arbitrarily. It becomes possible to fix in position.

Further, the manual operation lever and the operation shaft of the manual inching valve are formed by fitting a pin fixed to the manual lever into a forked portion of a forked lever fastened to the operation shaft of the manual inching valve. By configuring the link device, the angle between the manual operation lever position when the manual inching valve is fully opened and the forked lever position is substantially 90 °, it is possible to increase the effective operation angle of the manual operation lever, This makes it possible to easily fine-tune the speed in the low-speed range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part of a hydraulic circuit diagram of an HST vehicle according to the present invention. In the conventional hydraulic circuit described with reference to FIG. 7, an inching valve 9 connected to a brake pedal (indicated by reference numeral 21 in FIG. Is provided with a manual inching valve 31 in parallel with the above. The other devices in FIG. 1 are the same as those described with reference to FIG. 7, wherein 1 is a hydraulic oil tank, and 8 is a forward / reverse switching valve.

Next, the operation of the embodiment described with reference to FIG. 1 will be described. The vehicle speed can be controlled by operating the inching valve 9 in the case of foot movement and operating the manual inching valve 31 in the case of manual operation. It is.

Next, the manual inching operation lever will be described. FIG. 2 is a side view of a main part of the driving control device,
FIG. 3 is a view taken in the direction of arrows AA in FIG. 2, and FIG. 21 inching valve 9 in FIG. A brake pedal coupled to (see also FIG. 1), and operates the operating lever 32, about an axis of rotation 33, 32 _1, 32 ₂ position twice indicated by the two-dot chain line The pin 34 fixed to the vicinity of the root of the operating lever 32 is fitted into a forked portion of a forked lever 36 fastened to the operating shaft 35 of the manual inching valve 31 so that the operating lever 32 is connected to 32 ₁ , 32 _2. With the pin 3
The position 4 also rotates as 34 ₁ and 34 ₂ . Operation lever 32
Rotation angle theta ₂ between the position of the position and the 32 ₁ is idle, 3
Rotation angle theta ₁ with 2 ₁ position and 32 ₂ of the position is valid operation angle. 37 is a pipe from the manual inching valve 31, and 38 is a vehicle operation handle.

[0010] Then the feature operation shaft 35 the center of this embodiment, a line connecting the position 34 ₂ center manual inching valve 31 fully open when the pin 34, and the central rotary shaft 33, the pin 34
A By the angle α is close to 90 ° with the line connecting the position 34 _second center of, the effective operation angle theta ₁ to becomes large, it is made possible fine adjustment of the vehicle speed.

The principle by which the effective operation angle θ ₁ can be increased will be described with reference to FIG. FIG. 5 (a) in FIG. 5 is a conventional one, and the effective operation angle θ ₁ ′ is small because the angle α ′ is much larger than 90 °, but in this embodiment shown in FIG. When the angle α is close to 90 °, the effective operation angle θ ₁ corresponding to the inching valve operation angle β which is almost the same as that of the related art (indicated by β ′ in FIG. 5A) can be significantly increased. The angles θ ₂ ′ and θ ₂ are play angles.

As shown in FIG. 4, a disc spring 40 is mounted on a portion of the operating lever 32 where the rotating shaft 33 is mounted on the valve box 39, and the operating lever 32 can be arbitrarily moved by the elasticity of the disc spring 40. It becomes possible to semi-fix to the position.

[0013]

[Effects of the Invention] The present invention is constructed as described in detail above. Therefore, in the case of an HST vehicle equipped with a snow removal work machine or a road cleaning work machine that works at a constant speed for a long time, the vehicle maintains a constant speed. Even if the brake pedal is not depressed, if the lever is manually fixed to an appropriate position to operate the manual inching valve, the desired constant speed can be automatically maintained. By the action of the link device connecting the lever and the manual inching valve, continuous fine adjustment in a low speed range is facilitated, and a great effect is obtained that driving performance is extremely improved.

[Brief description of the drawings]

FIG. 1 is a main part of a hydraulic circuit diagram of an embodiment of the present invention.

FIG. 2 is a side view of a main part of the driving control device according to the embodiment of the present invention;

FIG. 3 is a view as viewed in the direction of arrows AA in FIG. 2;

FIG. 4 is a diagram illustrating displacement as viewed in the direction of arrows BB in FIG. 3;

FIGS. 5 (a) and 5 (b) are diagrams illustrating the operation principle of a manual inching lever link device.

FIG. 6 is an external side view of a wheel loader equipped with a snow removing work machine.

FIG. 7 is a hydraulic circuit diagram of a conventional HST vehicle.

[Explanation of symbols]

 31 Manual inching valve 32 Operation lever 33 Rotary axis 34 Pin 35 Operation axis 36 Bifurcated lever 40 Disc spring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-55031 (JP, A) JP-A-61-196832 (JP, A) JP-A-4-4555 (JP, U) JP-A-49 66116 (JP, U) Japanese Utility Model Hei 5-27422 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60K 41/00-41/28

Claims (3)

(57) [Scope of request for utility model registration] In a hydraulic circuit of a vehicle speed control device for a hydrostatically driven vehicle, a manual inching valve (31) is provided in parallel with an inching valve (9) operated by a brake pedal (21), and the manual inching valve (31) is provided.
Is operated by a manual operation lever (32). 2. A hydraulic circuit of a vehicle speed control device for a hydrostatically driven vehicle, wherein a manual inching valve (31) is provided in parallel with an intiming valve (9) operated by a brake pedal (21). )
Is operated by a manual operation lever (32) that can be fixed at an arbitrary position by attaching a disc spring (40) to the rotation shaft (33) of the manual operation lever (32). vehicle speed control system of claim 1, wherein. 3. A pin (34) fixed to the operation lever (32) is fastened to the operation shaft (35) between the operation lever (32) and the operation shaft (35) of the manual inching valve (31). A link device is fitted into the forked portion of the forked lever (36), and the operation lever (32) when the manual inching valve is fully opened, (the position code is (32 ₂ )), and the forked lever (36) 2. The vehicle speed control device according to claim 1, wherein the angle (α) is approximately 90 °.