JPH05248406A - Running speed control method for construction machinery - Google Patents

Abstract

PURPOSE:To operate running levers at the same angular amount regardless of the speed of the preset speed and to enable running at a required setting speed by inputting a displacement detection signal of the running lever and a signal of a running speed setting operation unit to a controller. CONSTITUTION:A working mode change-over switch 20 and a running speed setting operation unit 27 are operated, a signal from the change-over switch 20 is input to a controller 19' to decide the target rotating speed of an engine 17, and displacement detecting signals of potentiometers 25, 26 are input to the controller 19' by running levers 1L, 1R. According to the above signals, a preset speed signal of the running speed setting operation unit 27, and a pump characteristic relative to the current preset speed of a memory 23, a pump tilting amount command signal is output to an electromagnetic proportional pressure reducing valve 24. The pilot pressure corresponding to the signal works on regulators 14, 15, the pump tilting amount of the variable pumps 12', 13' is regulated in so as to discharge the preset amount. Accordingly, regardless of the speed of the required preset speed, the running levers are operated at the same angle to run at the required preset speed.

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 method for a construction machine such as a crawler hydraulic excavator.

[0002]

2. Description of the Related Art FIG. 4 is a prior art traveling speed control circuit diagram of a hydraulic excavator. In the figure, 1L and 1R are a pair of left and right traveling levers (including pedals), 2F and 3F
Is a left / right forward pilot valve, 2R, 3R is a left / right reverse pilot valve, 4L, 4R is a left / right traveling motor capable of 1-2 speed switching, 5 is an electromagnetic switching valve, 6 is a 1-2 speed switching Switches, 7L and 7R are pilot switching valves for controlling the traveling motors 4L and 4R, 8, 9 and 10 are pilot switching valves for controlling various hydraulic actuators for work (not shown), 11 is a straight traveling valve, and 12 and 13 Are the first and second pumps, 14 and 15 are the first pump 12 and the second pump, respectively.
Each of the regulators of the pump 13, 16 is a pilot pump, 17 is an engine, 18 is a governor of the engine 17, 19 is a controller, 20 is a work mode changeover switch, 21 is a control motor for adjusting and driving the governor 18, reference numerals Y, R -B, ha, ni are pilot valves 2F,
The connection of the pilot pipeline which connects 2R, 3F, 3R and the pilot switching valves 7L, 7R is shown. FIG. 5 is a chart showing pump discharge amounts discharged from the first pump 12 and the second pump 13 according to the operation of the traveling levers 4L and 4R.

In a conventional traveling speed control circuit, as shown in FIGS. 4 and 5, an engine 17 and a variable displacement type first pump 12 and a second pump 13 (hereinafter referred to as the first pump 12) driven by the engine 17 are used. And the second pump 13 are collectively referred to as a variable pump), and the pressure oil flow rate from the variable pump is adjusted by the traveling motors 4L and 4R according to the displacement amount of the traveling levers 1L and 1R (hereinafter, simply referred to as traveling lever).
I am trying to supply it to. That is, the pilot valves (2F, 2R, 3
A pilot secondary pressure corresponding to the operation displacement amount of the traveling lever is derived from one of the pilot valves F, 3R) to switch the pilot switching valves 7L, 7R.
Since the traveling motors 4L and 4R rotate, the hydraulic excavator moves forward or backward. By operating the switch 6 that communicates with the solenoid 22 of the electromagnetic switching valve 5 before starting the traveling, the rotation speed of the traveling motors 4L, 4R can be selected to the first speed or the second speed. The traveling motor 4
L and 4R can be switched to 1-2 speed,
By switching the work mode changeover switch 20, the engine rotation is selected to each of H (high-speed rotation for heavy load), S (medium-speed rotation for normal load), FC (low-speed rotation for fine operation work). Switching can be performed. Further, when the switch is operated to D, the engine speed can be reduced to eliminate the change in traveling speed due to the simultaneous operation of the work attachment of the hydraulic excavator and traveling.

[0004]

When the crawler type hydraulic excavator travels in a narrow space or a site where the scaffolding is poor, it travels at a low speed to ensure safety. In the case of traveling at this low speed, in the prior art, the operation angle of the travel lever is kept in the fine operation range, or the engine speed is lowered to a low speed by a travel speed setting means such as a work mode changeover switch. These operating methods and procedures are difficult and difficult to operate. Further, when the engine speed is set to a low speed, the engine speed must be increased again when the operating speed of the work attachment is to be increased next time, which is troublesome and inconvenient. SUMMARY OF THE INVENTION It is an object of the present invention to provide a traveling speed control method that does not require the traveling lever to be held in a fine control range when a hydraulic excavator is traveling at low speed, and that can eliminate the troublesome work of switching the engine speed to a low speed. And

[0005]

According to the traveling speed control method of the present invention, the set maximum pump discharge amount at each set speed set by adjusting the traveling speed setting operation section and the operation of the traveling lever are set. As the pilot pressure derived from the above rises from a predetermined low pressure to a predetermined high pressure, the pump discharge rate increases and the pump characteristics that reach the above-mentioned set maximum pump discharge rates are stored in the controller and the running of the construction machine is stored. When performing, when the required set speed is selected, the traveling lever can be operated at substantially the same angle amount regardless of whether the set speed is slow or slow so that the vehicle can travel at the required set speed. Further, the pump discharge amount determined by the pilot secondary pressure derived in accordance with the operation of the traveling lever is compared with the pump discharge amount determined by the speed setting of the traveling speed setting operation unit, and the smaller pump discharge amount is suppressed. I did it.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a travel speed control circuit diagram according to the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. 14 'and 15' are regulators of the first pump 12 'and the second pump 13' (hereinafter referred to as variable pumps), 19 'is a controller, 23 is a memory (ROM) of the controller 19', 2
Reference numeral 4 is an electromagnetic proportional pressure reducing valve as an electro-hydraulic converter, 25 and 26 are potentiometers for detecting the displacement amounts of the traveling levers 1L and 1R, and 27 is a traveling system in which the required traveling speed can be adjusted steplessly or stepwise. It is a speed setting operation unit. Instead of the potentiometers 25 and 26, a detection unit such as a pressure sensor (not shown) that can detect the operation displacement amount of the traveling lever may be provided. 2 and 3 show
6 is a chart showing the relationship between the pilot secondary pressure derived from the pilot valve and the pump discharge amount.

Next, the traveling speed control method of the present invention will be described with reference to FIGS.
Referring to FIG. In the present invention, the traveling levers 1L, 1
The potentiometers 25 and 26 for detecting the operation displacement amount of R (hereinafter referred to as a traveling lever) are provided, and the displacement detection signals from the potentiometers 25 and 26 are supplied to the controller 19 '.
And the pilot secondary pressure derived in accordance with the operation of the travel lever, respectively, at each set speed set by adjusting the travel speed setting operation unit 27. The pump characteristics such that the pump discharge amount increases as the pressure rises from a low pressure to a predetermined high pressure and reaches the set maximum pump discharge amounts (the pump characteristics shown in FIG. 2 and shown by reference numeral E in FIG. 1). The memory (ROM) 2 of the controller 19 '
I memorized it in 3. Therefore, when traveling the hydraulic excavator, first the work mode selector switch 2 is selected according to the work situation.
0, travel motors (4L and 4R) 1-2 speed changeover switch 6, and travel speed setting operation unit 27 are operated. The signal from the work mode switch 20 is the controller 1
By inputting 9 ', the target rotation speed of the engine 17 is determined. Next, when the operation of the traveling lever is started, displacement detection signals from the potentiometers 25 and 26 are input to the controller 19 '. In the controller 19 ',
The displacement detection signal, the set speed signal from the traveling speed setting operation unit 27, and the pump characteristic corresponding to the current set speed stored in the memory 23 (the pump characteristic curves a, b, c in FIGS. 1 and 2). , D, etc., and a pump displacement command signal is output to the electromagnetic proportional pressure reducing valve 24. The pilot pressure corresponding to the pump displacement command signal acts on the regulators 14 'and 15' from the electromagnetic proportional pressure reducing valve 24, so that the variable pump discharges the pump discharge amount in the set pump characteristics. The tilt amount is adjusted. As a result, the traveling lever can be operated at substantially the same angle regardless of whether the required set speed is slow (high speed, medium speed, low speed, or slow speed), and the vehicle can travel at the required set speed.

Further, the pump discharge amount determined by the pilot secondary pressure derived in accordance with the operation of the traveling lever and the pump discharge amount determined by the speed setting of the traveling speed setting operation unit 27 are compared, and the smaller pump The amount of discharge was suppressed. As a result, when the required traveling speed υ 1 (shown in FIG. 3) is set in the traveling speed setting operation unit 27, it is derived according to the displacement amount of the traveling lever when the traveling lever is tilted from the neutral position. When the pilot secondary pressure from the pilot valve reaches the pressure P1, the pump discharge amount also increases to Q1. However, even if the travel lever is tilted more than the above time, the pump tilt amount is not adjusted. That is, the pilot secondary pressure derived from the pilot valve P2
, P3 --- Pmax Even if the pressure is increased to a high pressure, the pump discharge rate remains Q1. Therefore, the traveling speed setting operation unit 2
For example, when 7 is set to a considerably low speed, even if the traveling lever is inadvertently tilted to a large angle, the hydraulic excavator does not start rapidly, which is safe.

[0009]

In the prior art, when the hydraulic excavator travels in a narrow space or in a place where the scaffolding is poor, in the prior art, the operation angle of the travel lever is kept in the fine operation range or the engine speed is lowered to a low speed. Then, when the engine speed was set to a low speed, the engine speed had to be increased again when it was desired to increase the operating speed of the work attachment next time. The above-mentioned operation method is difficult to operate and is troublesome. However, in the traveling speed control method of the present invention, the set maximum pump discharge amount at each set speed set by adjusting the traveling speed setting operation unit and the pilot pressure derived according to the operation of the traveling lever are set to predetermined values. The pump characteristic is stored in the controller such that the pump discharge amount increases as the pressure rises from the low pressure to a predetermined high pressure and reaches the set maximum pump discharge amount. Therefore, when the operation of the travel lever is started when the hydraulic excavator travels, the displacement detection signal from the potentiometer of the travel lever, the set speed signal of the travel speed setting operation unit,
Based on the storage of the pump characteristics stored in the memory, the controller outputs a pump displacement command signal to the electromagnetic proportional pressure reducing valve. Since the pilot pressure corresponding to the pump displacement command signal acts on the regulator from the electromagnetic proportional pressure reducing valve, the pump displacement of the variable pump is adjusted. Therefore, when the required set speed is selected when traveling the hydraulic excavator, the traveling lever can be operated at substantially the same angle amount to travel at the required set speed regardless of whether the set speed is slow or slow. Therefore, the operability of the traveling lever of the construction machine and the workability can be improved. Further, the pump discharge amount determined by the pilot secondary pressure derived in accordance with the operation of the traveling lever is compared with the pump discharge amount determined by the speed setting of the traveling speed setting operation unit, and the smaller pump discharge amount is suppressed. I did it. As a result, the pump discharge amount is controlled to the small discharge operation side,
Even if the travel lever is inadvertently operated to a large angle, the hydraulic excavator does not start rapidly, thus ensuring safety.

[Brief description of drawings]

FIG. 1 is a traveling speed control circuit diagram of a hydraulic excavator according to the present invention.

FIG. 2 is a chart showing a relationship between a pilot secondary pressure from a travel lever pilot valve and a pump discharge amount.

FIG. 3 is a chart showing a relationship between a pilot secondary pressure from a travel lever pilot valve and a pump discharge amount.

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

FIG. 5 is a chart showing a relationship between a pilot secondary pressure from a travel lever pilot valve and a pump discharge amount.

[Explanation of symbols]

 1L, 1R traveling lever 4L, 4R traveling motor 6 (1-2 speed switching) switch 12, 12 'first pump 13, 13' second pump 14, 14 ', 15, 15' regulator 17 engine 19, 19 ' Controller 20 Work mode switch 24 Electromagnetic proportional pressure reducing valve 25, 26 Potentiometer 27 Travel speed setting operation unit

Claims (3)

[Claims] 1. An engine and a variable pump driven by the engine are provided, 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. In the traveling speed control circuit which is controlled via the detecting means for detecting the displacement amount of the traveling lever, and the predetermined traveling speed is set based on the signal from the traveling speed setting operation part. Method for controlling traveling speed of construction machine. 2. The traveling speed control method for a construction machine according to claim 1, wherein the set maximum pump discharge amount at each set speed set by adjusting the traveling speed setting operation unit and the traveling The controller stores the pump characteristics that the pump discharge amount increases as the pilot pressure derived in response to the operation of the lever increases from the predetermined low pressure to the predetermined high pressure, and reaches the set maximum pump discharge amount, respectively. When the required set speed is selected when running the construction machine, regardless of whether the set speed is slow or slow, the travel lever can be operated at almost the same angle amount to run at the required set speed. Method for controlling traveling speed of construction machine. 3. A traveling speed control method for a construction machine according to claim 1 or 2, wherein a pump discharge amount determined by a pilot secondary pressure derived according to an operation of a traveling lever, and traveling. A traveling speed control method for a construction machine, comprising: comparing a pump discharge amount determined by a speed setting of a speed setting operation unit to a smaller pump discharge amount.