JP3111611B2 - Travel speed control device for construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling speed control apparatus for a construction machine such as a crawler hydraulic excavator or a working vehicle.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional traveling speed control device for a hydraulic shovel. In the figure, 1L,
1R is a pair of left and right running levers (including pedals),
Reference numerals 2F and 3F denote left and right forward pilot valves, 2R and 3R denote left and right reverse pilot valves, 4L and 4R denote left and right traveling motors capable of 1-2 speed switching, and 5L and 5R denote left and right traveling motors 4L and 4R. Rotation speed switching unit, 6L, 6R
Is a speed switching valve, 7 is a 1-speed / 2-speed switching electromagnetic switching valve, 8 is a solenoid of the electromagnetic switching valve 7, 9L and 9R are pilot switching valves for controlling the traveling motors 4L and 4R, respectively.
10 and 11 are pilot pressure receiving portions of the pilot switching valves 9L and 9R, respectively, 12 and 13 are first and second variable displacement pumps, 14 is an oil tank, 15 is a pilot pump,
16 is an engine, 17 is a governor of the engine 16, 18 is a controller, 20 is a work mode changeover switch, 21 is an accelerator lever device, 22 is an accelerator lever of an accelerator lever device 21, and 23 is a potentiometer for detecting the operation position of the accelerator lever 22. , 24 are 1-2 speed changeover switches for the traveling motors 4L and 4R, 25 is the governor 17
A stepping motor which is a control motor for adjusting and driving the
Reference numeral 26 denotes a rotation sensor that detects the engine speed. Also, the symbols Ey, Loro, Harha, and Nini indicate the connection of the pilot pipeline.

In the prior art traveling speed control circuit shown in FIG. 4, a pair of traveling levers 1L and 1R are operated to change a pilot pressure (a pilot valve among 2F, 2R, 3F and 3R) from a pilot pressure (detailed description). Is the pilot secondary pressure) and the pilot switching valves 9L, 9
R is switched and the traveling motors 4L and 4R are operated. By operating the switch 24 communicating with the solenoid 8 of the electromagnetic switching valve 7 for 1-2 speed switching, the rotation speed of the traveling motors 4L, 4R can be selected to be first speed or second speed. In addition, during the operation of the construction machine, the work mode changeover switch 20 and the accelerator lever 22 of the accelerator lever device 21 are operated to required positions according to the magnitude of the work load. Operation position signals of the work mode changeover switch 20 and the accelerator lever 22 are input to the controller 18. The controller 18 makes a determination based on the operation position signal, and outputs a command signal from the controller 18 to the stepping motor 25. Since the stepping motor 25 rotates to adjust the governor 17, the rotation of the engine (16) can be set to a required speed. The engine speed is set to H mode (high-speed rotation for heavy load), S mode (medium-speed rotation for normal load), or FC mode (fine-speed rotation for fine operation) by selecting and switching the operation mode switch 20. ) Can be set. When the accelerator lever 22 is operated in the direction of the arrow L, the engine speed becomes a low idle speed,
When the operation is performed in the direction of arrow F, high idle rotation is performed.

[0004]

When a construction machine equipped with the prior art traveling speed control device travels, the operation lever of the accelerator lever device is set to the high idling position and the work mode changeover switch is set to a required mode. Switch to the position and operate the traveling motor 1-2 speed changeover switch. Therefore, the traveling speed setting stage number of the construction machine is
It is limited to a plurality of stages in which the number of work mode switching positions is doubled. Therefore, when the construction machine travels on a narrow work site with a bad ground, it cannot move at a required optimum traveling speed, which may cause a trouble. An object of the present invention is to solve the above problems.

[0005]

A detecting means for detecting an amount of displacement of a traveling lever, a traveling speed adjusting means capable of adjusting and setting a required traveling speed, a signal from the detecting means and a signal from the traveling speed adjusting means. A signal comparison unit that compares and calculates a signal and outputs a command value signal based on a smaller signal of the signal from the detection unit and the signal from the traveling speed adjustment unit; and a variable based on the command value signal. And a pump discharge amount setting means for setting a pump discharge amount of the pump, so that the vehicle can travel within the range of the adjusted and set traveling speed.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a main part circuit diagram of a construction machine provided with a traveling speed control device of the present invention. In the figure, the same reference numerals are given to components using the same components as the conventional technology. 27 is a regulator which is a pump discharge amount setting means of the first and second pumps 12 and 13 (hereinafter, simply referred to as variable pumps); 28 is an electromagnetic proportional pressure reducing valve which is an electro-oil converter;
Is a controller as signal comparing means, 30 is a traveling speed setting operation unit as traveling speed adjusting means, and 34 and 35 are potentiometers for detecting displacements of the traveling levers 1L and 1R, respectively. Note that the traveling speed setting operation unit 30 includes:
Step speed required (volume-operated stepless)
This is a traveling speed adjustment means that can be adjusted or set stepwise or stepwise. Further, instead of the potentiometers 34 and 35, a detecting means such as a pressure sensor (not shown) which can detect the operation displacement amount of the traveling lever may be provided. FIG. 2 is a main part circuit diagram showing functions of the controller 29.

Next, the configuration of the traveling speed control device of the present invention will be described with reference to FIGS. In the traveling speed control device of the present invention, potentiometers 34 and 35 for detecting the displacement amounts of traveling levers 1L and 1R (hereinafter referred to as traveling levers).
And a traveling speed setting operation unit 30. By inputting the traveling lever displacement amount signals from the potentiometers 34 and 35 and the traveling speed adjustment signal from the traveling speed setting operation unit 30 to the controller 29,
In step 9, the pump tilt command value V1 based on the travel lever displacement amount signal and the pump tilt command value V2 based on the travel speed adjustment signal are calculated, and the smaller of the pump tilt command values V1 and V2 is calculated. Command value signal from the electromagnetic proportional pressure reducing valve 28
To output to the regulator 27 of the variable pump via the.

Next, the operation of the traveling speed control device of the present invention will be described. When it is desired to run the construction machine at a required speed, the traveling speed setting operation unit 30 is manually turned (moved by a finger) and adjusted by turning (manually moving the finger) to match the required traveling speed scale (not shown). The traveling speed adjustment signal from the traveling speed setting operation unit 30 is input to the traveling speed adjustment signal reading unit 31 of the controller 29, and the signal value from the traveling speed adjustment signal reading unit 31 is input to the output command calculation unit 33. .
By operating the travel lever, travel lever displacement amount signals from the potentiometers 34 and 35 are input to the output command calculation unit 33. In the output command calculation unit 33,
A pump tilt command value V1 based on the travel lever displacement amount signal and a pump tilt command value V2 based on the travel speed adjustment signal.
And outputs the smaller command value signal of the pump displacement command values V1 and V2 to the electromagnetic proportional pressure reducing valve 28. As a result, the pilot secondary pressure derived from the electromagnetic proportional pressure reducing valve 28 is controlled by the variable pump regulator 27.
Act on. Since the regulator 27 operates, the pump displacement amount of the variable pump (the pump discharge flow rate CC / rev per one rotation of the pump shaft) is adjusted.

FIG. 3 is a chart showing the relationship between the displacement of the traveling lever and the pump discharge. When it is desired to run the construction machine at a required traveling speed, the driver sets the traveling speed setting operation unit 30 to, for example, the traveling speed v1 (shown in FIG. 3). In this case, when the traveling lever is tilted from the neutral position, when the displacement of the traveling lever becomes θ1, the pump discharge amount also increases to Q1. However, the pump discharge amount remains at Q1 even if the tilting operation is made larger (in the directions of Q2 and Q3) than the above time. Therefore, for example, when the traveling speed setting operation unit 30 is set to a considerably low speed,
Even if the traveling lever is inadvertently tilted to a large angle, the construction machine is not quickly started, so it is safe.

[0010]

According to the present invention, when the construction machine travels, the required traveling speed can be set within the range from the minimum to the maximum traveling speed by adjusting the traveling speed setting operation section. When the driver tilts the traveling lever from the neutral position, the displacement amount of the traveling lever increases and the pump discharge amount also increases, but after reaching the pump discharge amount corresponding to the set traveling speed, Even if the traveling lever is further tilted, the pump discharge amount does not increase. Therefore, for example, when the traveling speed setting operation unit is set at a considerably low speed, even when the traveling lever is inadvertently tilted to a large angle, the construction machine does not start rapidly, so that traveling safety can be achieved. .

[Brief description of the drawings]

FIG. 1 is a main part circuit diagram of a construction machine provided with a traveling speed control device of the present invention.

FIG. 2 is a main part circuit diagram showing functions of a controller in the present invention.

FIG. 3 is a table showing a relationship between a displacement amount of a traveling lever and a pump discharge amount in the present invention.

FIG. 4 is a diagram of a conventional traveling speed control circuit.

[Explanation of symbols]

 1L, 1R Traveling lever 4L, 4R Traveling motor 12, 13 First and second pumps (variable pumps) 18, 29 Controller 27 Regulator 28 Electromagnetic proportional pressure reducing valve 30 Traveling speed setting operation unit 34, 35 Potentiometer

Claims (1)

(57) [Claims] 1. A detecting means for detecting an amount of displacement of a traveling lever, a traveling speed adjusting means capable of adjusting and setting a required traveling speed, and comparing a signal from the detecting means with a signal from the traveling speed adjusting means. Signal comparing means for calculating and outputting a command value signal based on the smaller signal of the signal from the detecting means and the signal from the traveling speed adjusting means; and pump discharge of the variable pump based on the command value signal. A travel speed control device for a construction machine, comprising: a pump discharge amount setting means for setting an amount; and enabling travel within a range of the adjusted and set travel speed.