JPH07117501A - Travel speed controller of travel vehicle - Google Patents

Abstract

PURPOSE:To move at the optimum speed according to a ground condition by providing detecting means to detect the displacement of a travel lever and a travel speed regulating means, setting a required travel speed on the basis of signals from these means. CONSTITUTION:Travel lever displacement signals from potentiometers 34, 35 and a travel speed regulation signal from a travel speed setting operation portion 30 are inputted to a controller 29. At the controller 29, then, pump inclination command values based on the travel lever displacement signals and a pump inclination command value based on the travel speed regulation signal are operated. Out of these command values, the smallest one is outputted as a command value signal to a regulator 27 for variable pumps 12, 13, and thus a required travel speed is set. After a pump discharge amount to cope with the set travel speed is attained, the discharge amount is not increased even if the travel lever is inclined further, so even if a large inclination operation is conducted carelessly, a speed which is more than the set travel speed is not brought on, and thus safety is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a traveling speed control device for construction machines such as crawler type hydraulic excavators and work vehicles.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional traveling speed control system for a hydraulic excavator. In the figure, 1L,
1R is a pair of left and right traveling levers (including pedals),
2F and 3F are left and right forward pilot valves, 2R and 3R are left and right backward pilot valves, 4L and 4R are left and right traveling motors capable of switching between 1 and 2 speed, and 5L and 5R are left and right traveling motors 4L and 4R. Rotation speed switching unit, 6L, 6R
Is a speed switching valve, 7 is an electromagnetic switching valve for switching between 1st speed and 2nd speed, 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.
Reference numerals 10 and 11 are pilot pressure receiving portions of the pilot switching valves 9L and 9R, 12 and 13 are first and second variable displacement pumps, 14 is an oil tank, 15 is a pilot pump,
Reference numeral 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 the accelerator lever device 21, 23 is a potentiometer for detecting the operating position of the accelerator lever 22. , 24 are 1-2 speed changeover switches for the traveling motors 4L and 4R, and 25 is a governor 17
A stepping motor which is a control motor for adjusting and driving the
Reference numeral 26 is a rotation sensor for detecting the engine speed. The symbols Ei, Loro, Harha, and Nini indicate the connection of the pilot lines, respectively.

In the prior art traveling speed control circuit shown in FIG. 4, the pilot pressure (more specifically, one of the pilot valves 2F, 2R, 3F and 3R) is operated by operating a pair of traveling levers 1L and 1R. Is the pilot secondary pressure) and the pilot switching valves 9L, 9L
R is switched and controlled, and the traveling motors 4L and 4R are operated. Further, by operating the switch 24 communicating with the solenoid 8 of the 1-2 speed switching electromagnetic switching valve 7, the rotation speed of the traveling motors 4L, 4R can be selected to the 1st speed or the 2nd speed. Further, at the time of working on the construction machine, the work mode changeover switch 20 and the accelerator lever 22 of the accelerator lever device 21 are operated to desired positions according to the magnitude of the work load. The 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 rotationally operates to adjust the governor 17, the engine (16) rotation can be set to a required rotation speed. The engine speed can be changed 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 work) by selecting and operating the work mode selector switch 20. ) Can be set to either. When the accelerator lever 22 is operated in the direction of arrow L, the engine rotation becomes low idle rotation,
When operated in the direction of arrow F, high idling rotation is performed.

[0004]

When a construction machine equipped with a prior art traveling speed control device travels, the operating lever of the accelerator lever device is set to the high idling position and the work mode switch is set to a desired mode. Switch to the position and operate the 1-2 speed selector switch for the traveling motor. Therefore, the traveling speed setting number of steps 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 at a narrow work site where the ground is poor, it cannot move at the required optimum traveling speed, which may cause trouble. The present invention aims to solve the above problems.

[0005]

In the traveling speed control device of the present invention, a detecting means for detecting the displacement amount of the traveling lever and a traveling speed adjusting means are provided, and the traveling lever displacement amount signal from the detecting means is provided. By inputting the travel speed adjustment signal from the travel speed adjusting means to the controller, the controller calculates the individual pump displacement command values based on the above signals, and the smaller command displacement value of the pump displacement command values. The signal is output to the regulator of the variable pump.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of a main part of a construction machine equipped with the traveling speed control device of the invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numeral 27 is a regulator for the first and second pumps 12 and 13 (hereinafter, simply referred to as variable pump), 28 is an electromagnetic proportional pressure reducing valve which is an electro-oil converter, 29 is a controller, 30 is a traveling speed setting as traveling speed adjusting means. Operation part, 34, 35
Is a potentiometer that detects the amount of displacement of each of the traveling levers 1L and 1R. The traveling speed setting operation unit 3
Reference numeral 0 denotes a traveling speed adjusting means capable of adjusting and setting the required traveling speed steplessly (volume operation type steplessly) or stepwise. Further, instead of the potentiometers 34 and 35, a detection unit such as a pressure sensor (not shown) that can detect the operation displacement amount of the traveling lever may be provided. Figure 2
FIG. 3 is a circuit diagram of a main part showing the function 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, the potentiometers 34 and 35 for detecting the displacement amounts of the traveling levers 1L and 1R (hereinafter, referred to as traveling levers).
And a traveling speed setting operation unit 30 are provided, and 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 are input to the controller 29, whereby the controller 2
At 9, the pump displacement command value V1 based on the travel lever displacement signal and the pump displacement command value V2 based on the travel speed adjustment signal are calculated, and the smaller one of the pump displacement command values V1 and V2 is calculated. Command value signal of the electromagnetic proportional pressure reducing valve 28
It is configured 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 travel the construction machine at a required speed, the traveling speed setting operation unit 30 is manually rotated (moved by fingers) to be adjusted 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, the travel lever displacement amount signals from the potentiometers 34 and 35 are input to the output command calculation unit 33. In the output command calculator 33,
Pump tilt command value V1 based on the travel lever displacement amount signal and pump tilt command value V based on the travel speed adjustment signal.
2 is calculated, and the command value signal of the smaller one of the pump displacement command values V1 and V2 is output 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 regulated by the regulator 2 of the variable pump.
Act on 7. Since the regulator 27 operates, the pump displacement amount (pump discharge flow rate CC / rev per one rotation of the pump shaft) of the variable pump is adjusted.

FIG. 3 is a chart showing the relationship between the displacement amount of the traveling lever and the pump discharge amount. When the construction machine is desired to travel at a required traveling speed, the driver sets the traveling speed setting operation unit 30 to the traveling speed v1 (shown in FIG. 3), for example. In this case, when the traveling lever is tilted from the neutral position and the displacement amount of the traveling lever becomes θ1, the pump discharge amount also increases to Q1. However, even if the tilting operation is performed further than the above point (in the directions of Q2 and Q3), the pump and the discharge amount remain at Q1. Therefore, 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 does not start rapidly, which is safe.

[0010]

When a construction machine equipped with a traveling speed control device of the prior art travels, the operating lever of the accelerator lever device is set to the high idling position, and the work mode switch is switched to the required mode position. ,
Operate the 1-2 speed selector switch for the traveling motor. Therefore, the traveling speed setting number of stages of the construction machine is limited to a plurality of stages in which the number of operation mode switching positions is doubled. Therefore, when the construction machine travels at a narrow work site where the ground is poor, it cannot move at the required optimum traveling speed, which may cause trouble. However, the traveling speed control device of the present invention is provided with the detecting means for detecting the changed position of the traveling lever and the traveling speed adjusting means, and the traveling lever displacement amount signal from the detecting means and traveling from the traveling speed adjusting means. By inputting the speed adjustment signal to the controller, the controller calculates individual pump displacement command values based on both of the above signals and outputs the result to the regulator of the variable pump. Thereby, when the construction machine is traveling, the required traveling speed can be set within the range of 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 tilted further, the pump discharge amount does not increase. Therefore, when the traveling speed setting operation section is set to a considerably low speed, for example, even if the traveling lever is inadvertently tilted to a large angle, the construction machine does not transmit rapidly, so traveling safety can be ensured. .

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 1L, 1R Travel lever 4L, 4R Travel motor 12,13 1st, 2nd pump (variable pump) 18, 29 Controller 27 Regulator 28 Electromagnetic proportional pressure reducing valve 30 Travel speed setting operation part 34, 35 Potentiometer

Claims (2)

[Claims] 1. An engine and a variable pump driven by the engine are provided, and a flow rate of pressure oil from the variable pump is supplied to a traveling motor according to a displacement amount of a traveling lever, and an engine speed is controlled by a controller. A traveling speed control device for a traveling vehicle which is controlled by means of: a detecting means for detecting a displacement amount of a traveling lever; and a traveling speed adjusting means, wherein a required traveling is carried out based on signals from both means. A traveling speed control device for a traveling vehicle, characterized in that a speed is set. 2. The traveling speed control device for a traveling vehicle according to claim 1, wherein the controller is configured to input the traveling lever displacement amount signal and the traveling speed adjustment signal, and the controller is based on the both signals. A traveling speed control device for a traveling vehicle, characterized in that an individual pump displacement command value is calculated and the result is output to a regulator of a variable pump.