JPH0672188A - Clutch cutoff control device for working vehicle - Google Patents

Abstract

PURPOSE:To enable the simple adjustment of operating timing of a clutch and a brake in a working vehicle such as a wheel loader. CONSTITUTION:A clutch cutoff control device for a working vehicle is provided with a detecting means 32 for detecting the depression quantity of an inching pedal for braking a travel driving device as well as releasing a clutch, a setting means 31 for setting two or more reference depression quantities, and control means 33, 34 for releasing the clutch when the detected depression quantity exceeds the set reference depression quantity. Larger braking force is obtained as the depression quantity of the inching pedal 13 is larger, and the clutch is let off when the depression quantity of the inching pedal 13 exceeds the reference depression quantity. The grade of the reference depression quantity is adjusted by the setting means 31.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a wheel loader, etc.
The present invention relates to a clutch cutoff control device suitable for use in a work vehicle equipped with a traveling drive device and a front work device.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a schematic configuration of a wheel loader to which the present invention is applied. A wheel loader 1 has a prime mover 2 whose output is output via an output shaft 3 to a traveling transmission 4.
Is transmitted to the hydraulic pump 5 to drive the front and rear propeller shafts 6 and 7.
A front axle device 8 and a rear axle device 9 are connected to the front and rear propeller shafts 6 and 7, respectively. The front working device 10 such as a bucket is driven by the oil discharged from the hydraulic pump 5. 4a is a clutch that connects and disconnects the prime mover and the traveling drive device 50. The traveling drive device 50 includes the front and rear propeller shafts 6,
7 and the front and rear axle devices 8 and 9, and the like, and the traveling drive device 50 is provided with a brake device (not shown).

FIG. 8 shows the arrangement of pedals in the driver's seat of such a wheel loader. From the right side, an accelerator pedal 11 for adjusting the rotational speed of a prime mover such as a diesel engine and a traveling drive device are braked. Brake pedal 1
2 and an inching pedal 13 that disengages the clutch 4a built in the transmission 4 and brakes the traveling drive device. Reference numeral 14 is a steering wheel, and 15 is a forward / reverse switching and speed change lever.

In the wheel loader, when loading a load on a dump truck or the like, the front working device 10 such as a lift arm or a bucket arm is driven at a high speed while the vehicle is stopped. Therefore, while depressing the inching pedal 13 with the left foot to disengage the clutch and actuating the brake, the accelerator pedal 11 is depressed with the right foot to increase the engine speed.
The speed of the front working device is increased to improve work efficiency. Such an operation by the inching pedal 13 is called a clutch cutoff operation, and an approach operation to the dump truck at the time of loading work, that is, a cutting operation of the traveling driving force and a braking operation are smoothly performed.
Further, since the power of the traveling drive device is separated from the engine by the clutch cutoff, 100% of the horsepower of the engine can be distributed to the front working device, and the front working device can be operated speedily and powerfully.

9 and 10 are views showing an example of a conventional clutch cutoff device. In FIG. 9, when the inching pedal 13 is depressed, a hydraulic pressure proportional to the depression amount is generated from the pressure reducing valve 21 to operate the traveling brake, and when the inching pedal 13 is depressed more than a predetermined amount, the limit switch 22 is turned on. . In FIG.
The switch 23 is a switch that is turned on when the clutch cutoff function is used. When the switch 23 is on, the solenoid valve 24 is switched from the a position to the b position when the limit switch 22 is turned on, and the discharge of the hydraulic pump 25 is performed. Oil is supplied to the clutch cylinder 26 provided in the transmission to turn off the clutch. The ON position of the limit switch 22 can be adjusted by adjusting the position of the mounting block 27 as shown in FIG.

FIG. 11 is a characteristic diagram of the output pressure (brake pressure) of the pressure reducing valve 21 with respect to the stroke (depression amount) of the inching pedal 13. The braking pressure rises with the depression amount of the stroke S2, and the maximum with the depression amount of the stroke S10. Braking pressure is generated. The operation timing of the clutch and brake can be adjusted as follows. (a) Limit switch 22 depending on the stroke amount of stroke S ₁
Adjust to turn on so that the clutch turns off before the brakes begin to take effect. (b) Limit switch 22 depending on the stroke amount of stroke S ₂
If you adjust so that it will turn on, the clutch will turn off at the same time that the brakes begin to work. (c) Limit switch 22 depending on the stroke amount of stroke S ₃
If you adjust so that the clutch will turn on, the clutch will turn off after the brake is applied to some extent. Note that FIG. 12 is a graph showing the traveling drive force and the braking force when the clutch cutoff point is set as in the above (a) to (c), and a to c show the traveling drive force. Generally, when loading a load on a dump truck or the like, the clutch is adjusted so that the clutch is turned off at the stroke S ₁ , and at the time of lifting operation, the clutch is adjusted so that the clutch is turned off at the stroke S ₃ . In addition, it is also possible to freely adjust it according to the preference of the operator.

[0007]

However, the adjustment of the operation timing of the clutch and the brake by the clutch cutoff device shown in FIGS. 9 and 10 is performed by (1) stopping the vehicle and adjusting the ON position of the limit switch 22. ,
(2) Run the vehicle to check the operation timing of the clutch and brake, and (3) Stop the vehicle and adjust the operation timing of the clutch and brake again. Takes too long.

Another conventional clutch cut-off device is known in which a pressure switch is turned on when the brake pressure reaches a predetermined value and the clutch is turned off when the pressure switch is turned on. However, this method is not practical because the clutch-off timing must be changed by changing the set pressure itself at which the pressure switch is turned on. Even if a pressure switch whose on-pressure can be easily changed is used, it is unavoidable to perform the adjustment by the trial-and-error method as described above, and the work is complicated.

An object of the present invention is to provide a clutch cutoff device for a work vehicle, which can easily change the operation timings of the clutch and the brake.

[0010]

The present invention will be described with reference to FIG. 1, FIG. 7 and FIG. 8 which are one embodiment. The present invention is driven by a motor output transmitted through a clutch 4a. The invention is applied to a clutch cutoff control device for a work vehicle that includes a traveling drive device 50, a front working device 10 that is driven by the output of a prime mover, and an inching pedal 13 that releases a clutch and brakes the traveling drive device 50. The above-mentioned objects are as follows: detection means 32 for detecting the depression amount of the inching pedal 13, setting means 31 for setting a reference depression amount of 2 or more, and when the detected depression amount exceeds the set reference depression amount. This is achieved by including control means 33 and 34 for releasing the clutch 4a. As in claim 2, the operation unit 31a of the setting means 31
May be provided in the driver's seat. The setting means 31 in the control device according to claim 3 is capable of setting two kinds of modes corresponding to at least a mode suitable for the lifting work and a mode suitable for the dump loading work, and the operation unit has two kinds of modes. Either one of them can be selected.

[0011]

The larger the depression amount of the inching pedal 13, the greater the braking force. That inching pedal 1
When the depression amount of 3 exceeds the reference depression amount, the clutch is turned off. The size of the reference depression amount is changed by the operation unit 31a of the setting means 31. Therefore, when the reference depression amount is set to be small, the clutch is turned off before the braking force is generated or before the braking force is small. When the reference depression amount is set to be larger than a predetermined value, the clutch is turned off after the braking force is generated.

In the paragraphs of means and actions for solving the above problems, the reference numerals of the embodiments are given for easy understanding of the invention, but the present invention is not limited to the embodiments. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same parts as those in FIGS. 9 and 10 are designated by the same reference numerals, and the differences are mainly described. FIG. 1 is a diagram showing a configuration of a clutch cutoff device according to the present invention. The volume 31 provided in the driver's seat generates a voltage according to the rotational operation amount of the knob 31a, and the pressure sensor 32 detects the output pressure of the pressure reducing valve 21, that is, the depression amount of the inching pedal 13 and responds to the pressure. Generated voltage. The output voltage of the volume sensor 31 and the output voltage of the pressure sensor 32 are respectively applied to the input terminals of the comparator 33, and the output signal of the comparator 33 is the output voltage of the pressure sensor 32 from the volume 3.
It is inverted when the output voltage from 1 is exceeded. Comparator 3
The output voltage of 3 is applied to the input terminal of the AND gate 34,
A signal from the limit switch 22 that is turned on when the inching pedal 13 is depressed by a predetermined amount or more and a signal from the clutch cutoff function selection switch 23 are applied to the other input end of the AND gate 34. When both the clutch cutoff function selection switch 23 and the limit switch 22 are on, the AND gate 34 is in the enable state. The output of the AND gate 34 is connected to the solenoid portion 24S of the clutch cutoff solenoid valve 24 through the amplifier 35. The limit switch 22 is configured so that its ON position can be adjusted.

FIG. 2 is a graph showing the relationship between the depression amount of the inching pedal 13 and the brake pressure. In this embodiment, it is assumed that the position of the limit switch 22 is adjusted in advance so that the limit switch 22 is turned on at the depression stroke S ₁₁ of the inching pedal 13. In this embodiment, the timing of clutch and brake can be set as follows by changing the reference signal (reference pressure, that is, the reference depression amount) output from the volume 31. (A) If the reference signal is set to a voltage equivalent to zero brake pressure, the stroke S ₁₁
The clutch can be turned off at the position. (B) If the reference signal is set to a voltage corresponding to the brake pressure P ₁ , the stroke S ₁₂
The clutch can be turned off at the position. As described above, by changing the brake pressure with the volume 31 within the range of zero to the maximum value P _MAX ,
The operation timing of the clutch and the brake can be freely set within the hatched area in FIG.

The limit switch 22 shown in FIG. 1 may be omitted, and the circuit in that case is shown in FIG. 1 is different from FIG. 1 in that the signal from the clutch cutoff function selection switch 23 and the signal from the comparator 33 are used as inputs to the AND gate 34, and the other configurations are similar to those in FIG. The detailed description of the operation is omitted. For the circuit of Figure 3, as the graph of the stroke and the brake pressure of the inching pedal 4, the stroke S ₂
The clutch cutoff point can be adjusted within the above hatching range, but the clutch cannot be adjusted before the brake starts to work.

With the circuit configuration of FIG. 3 in which the limit switch 22 is omitted, in order to turn off the clutch before the brake starts to operate, an initial spring force is set in the brake cylinder operated by the brake pressure from the pressure reducing valve 21. Then, as shown in the graph of braking pressure and braking force shown in FIG. 5, the braking force may start to be generated at the braking pressure P _S. By doing so, as shown in FIG. 6, (a) when the reference signal is set to a voltage corresponding to the brake pressure P ₁ (<P _S ), the clutch is actuated at the position of the stroke S ₁₄ before the braking starts. Can be turned off. (B) If the reference signal is set to a voltage corresponding to the brake pressure P ₂ (> P _S ), the clutch can be turned off at the position of the stroke S ₁₅ after the brake starts to work. The broken line in FIG. 5 is a graph showing the relationship between the braking pressure and the braking force of the above-described second embodiment, and shows that the braking force is generated as the braking pressure rises.

In the embodiment shown in FIG. 1, the volume is used as the reference signal output means. However, for example, a dump loading mode selection switch and a hoisting mode selection switch are provided, and two kinds of voltage levels can be set by operating each switch. The signal of may be output. Further, an up / down switch may be provided so that the output voltage increases each time the switch is operated to the up side, and the output voltage decreases each time the switch is operated to the down side. Further, it is not essential to detect the operation amount of the inching pedal by the pressure of the pressure reducing valve, and it is also possible to detect the depression amount by an additional sensor.

In the above construction, the propeller shaft and the axle device driven by the output of the prime mover control the traveling drive device, the bucket, the lift arm and the like control the front working device, the volume controls the setting means, and the comparator 33 and the AND gate 34 control. Each means is configured.

[0019]

As described in detail above, according to the present invention, the operation timings of the clutch and the brake can be easily adjusted, so that the operator can freely adjust the operation timings prior to the work, and the operability is improved. It is possible to improve. According to the second aspect, it is possible to easily set the optimum operation timings of the clutch and the brake for the dump loading work and the lifting work.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a control device according to the present invention.

FIG. 2 is a graph showing the relationship between the stroke of the inching pedal and the brake pressure.

FIG. 3 is a block diagram of a control device according to another embodiment.

FIG. 4 is a graph showing a relationship between a stroke of an inching pedal and a brake pressure in another embodiment.

FIG. 5 is a graph showing the relationship between brake pressure and braking force.

FIG. 6 is a graph showing the relationship between the stroke of the inching pedal and the brake pressure in another embodiment.

FIG. 7 is a schematic overall configuration diagram of a wheel loader.

FIG. 8 is a diagram showing an arrangement of inching pedals.

FIG. 9 is a view showing the periphery of a conventional inching pedal.

FIG. 10 is a block diagram of a conventional clutch cutoff device.

FIG. 11 is a graph showing the relationship between the stroke of the conventional inching pedal and the brake pressure.

FIG. 12 is a graph showing the relationship between the stroke of the conventional inching pedal, the brake pressure, and the traveling driving force.

[Explanation of symbols]

 2 prime mover 4 transmission 4a clutch 5 hydraulic pump 13 inching pedal 21 pressure reducing valve 22 limit switch 23 clutch cutoff function selection switch 24 clutch solenoid valve 24S clutch solenoid valve solenoid 26 clutch cylinder 31 volume 32 pressure sensor 33 comparator 34 And gate

Claims (4)

[Claims] 1. A traveling drive device driven by an output of a prime mover transmitted through a clutch, a front working device driven by the output of the prime mover, and an inching pedal for releasing the clutch and braking the traveling drive device. In a clutch cut-off control device for a work vehicle including: a detection unit that detects a depression amount of the inching pedal; a setting unit that sets a reference depression amount of 2 or more; and the detected depression amount is set. A clutch cut-off control device for a work vehicle, comprising: a control unit that releases the clutch when the reference depression amount is exceeded. 2. The clutch cut-off control device for a work vehicle according to claim 1, wherein the operation unit of the setting means is provided in a driver's seat. 3. The control device according to claim 1, wherein the setting unit can set at least a mode suitable for a lifting operation and a mode suitable for a dump loading operation, and the operation unit has two types. A clutch cut-off control device for a work vehicle, characterized in that either one of the modes can be selected. 4. The clutch for a work vehicle according to claim 1, wherein the setting unit is configured to set an arbitrary reference depression amount according to an operation amount of the operation unit. Cut-off control device.