JPH02279838A - Hydraulic shock absorption-controlling device for construction machine - Google Patents

Abstract

PURPOSE:To relieve shocks in the stroke area of a piston by making a sensor sense approach of a piston of an oil-hydraulic cylinder to the end of its stroke, and by reducing discharge flow of an oil-hydraulic pump with a signal emitted from the sensor and sent through a controller. CONSTITUTION:A pressure signal to a direction-switching valve 24 for an oil- hydraulic cylinder 21 is inputted to a controller 43 by operation of a piston 22 of the oil-hydraulic cylinder 21 and a sensor switch 23. To an oil passage connecting a pilot pump 39 and a regulator 38 for the oil-hydraulic pump 37, a solenoid valve 40 is installed and discharge flow of the oil-hydraulic pump 37 is reduced by the controller 43 and the solenoid valve 40. By operation of an operating lever 33, pressure from the pilot pump 39 acts on the direction- switching valve 24 through the medium of a pilot valve 34. As the piston 22 approaches the end of its stroke, signal emitted by the sensor 23 is caught by the controller 43, which acts on the regulator 38 and reduction of the discharge flow of the pump can be made thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates primarily to a hydraulic shock absorber control device for a hydraulic cylinder installed in a construction machine such as a hydraulic excavator.

BACKGROUND OF THE INVENTION FIG. 2 is an overall side view of a wheeled hydraulic excavator. In the figure, 1 is the lower traveling body of the hydraulic excavator, 2 is the upper rotating body, 3 is the engine mounted on the upper rotating body 2, and 4
1 is a working attachment mounted on the front part of the upper revolving structure 2, and 5, 6.7 are hydraulic cylinders for driving the working attachment 4, which are a boom cylinder, an arm cylinder, and a packet cylinder, respectively.

FIG. 3 is a circuit diagram showing a conventional hydraulic shock absorbing control device. In FIG. 0, 8 is a hydraulic cylinder, 9 is a piston portion of the hydraulic cylinder 8, 10 is a directional control valve for the hydraulic cylinder 8,
11 is a hydraulic source for main pressure, 12 is an oil tank, 13 is a flow rate control valve, 14 is a detector provided in the hydraulic cylinder 8, 15 is a position signal generator, 16 is an operating speed calculation circuit, 17 is a buffer stroke start position setting 18 is an output signal calculation circuit, 19 is an output signal output device, and 20 is a relief valve.

Next, a conventional hydraulic shock absorber control device will be described. Third
The control circuit in the figure includes an operating speed calculation circuit 16 that calculates the operating speed of the hydraulic cylinder 8, a buffer stroke start position setting circuit 17 that sets a buffer stroke start position at every predetermined time based on the operating speed, and A comparator (CP) that determines whether the operating stroke position has reached the buffer stroke start position, and an output signal corresponding to the throttle opening area of the flow control valve 13 at predetermined time intervals upon receiving the signal from the comparator. It is composed of an output signal calculation circuit 18 that outputs. Thereby, when the piston portion 9 of the hydraulic cylinder 8 reaches the buffer stroke start position, the flow rate supplied to the hydraulic cylinder 8 is restricted, and a buffering effect is exerted.

Problems to be Solved by the Invention In conventional hydraulic shock absorber control devices, the flow rate on the return side of the hydraulic cylinder is restricted when the piston portion of the hydraulic cylinder approaches the stroke end. Therefore, even when the hydraulic cylinder has reached its stroke end, the main pressure hydraulic pump discharges a large amount of unnecessary oil. Therefore, the excess amount of oil was immediately returned to the oil tank through a relief valve or the like. The energy loss was large and the oil temperature rose, which had a negative impact on the hydraulic circuit equipment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a hydraulic shock absorber control device that reduces the discharge flow rate of a hydraulic pump when a piston portion of a hydraulic cylinder approaches a stroke end.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (1) A. Detecting that the piston portion of the hydraulic cylinder approaches the stroke end; Accordingly, the controller is configured to reduce the discharge flow rate of the hydraulic pump.

(2) A2: Detects when the piston portion of the hydraulic cylinder approaches the stroke end, and inputs the detection signal and the pressure signal of the pilot pressure applied to the directional control valve when operating the hydraulic cylinder to the controller. , B. On the other hand, a solenoid valve is interposed in the oil path that communicates the pilot pressure oil source and the hydraulic pump regulator, and the solenoid valve is normally set to the cutoff oil path position, and C. The piston part of the hydraulic cylinder is When the stroke end is approached, an output signal from the controller is outputted to the electromagnetic valve to reduce the pump discharge flow rate.

Operation A. When the piston of the hydraulic cylinder approaches the stroke end, both the detection signal from the detector installed in the hydraulic cylinder and the pressure signal of the pilot pressure acting on the directional control valve for the hydraulic cylinder are sent to the controller. is input.

The controller performs arithmetic processing based on the input signal and outputs an output signal to the solenoid valve. Since the solenoid valve is switched from the shutoff oil passage position to the open oil passage position, the pilot pressure acts on the hydraulic pump regulator via the solenoid valve.

The swash plate tilt angle of the hydraulic pump is adjusted and the pump discharge flow rate is reduced.

C. As described in items A and 4 above, when the piston portion of the hydraulic cylinder approaches the stroke end, the pump discharge flow rate can be reduced, and the impact in the stroke end region of the hydraulic cylinder can be alleviated.

Embodiments Hereinafter, embodiments of claims 1 and 2 of the present invention will be described in detail based on the drawings. FIG. 1 is a circuit diagram showing a hydraulic shock absorbing control device according to the present invention. In the figure, 21 is a hydraulic cylinder, for example, a boom cylinder, 22 is a piston portion of the hydraulic cylinder 21, 23 is a proximity sensor switch which is a detector provided on the hydraulic cylinder 21,
24 is a directional valve for the boom cylinder 21, 25 is a travel motor, 26 is a directional valve for the travel motor 25, 27 is a directional valve for another hydraulic actuator (not shown), 28
is a low pressure relief valve for setting negative control pressure, 29 is a throttle part, 30 is an oil tank, 31 is a remote control valve for operating the boom cylinder 21, 32 is a remote control valve 3
The operation levers 33 and 34 of 1 are pilot valves of the remote control valve 31, 35-36 are pilot oil passages for when the boom cylinder 21 is extended, 37 is a hydraulic pump for main pressure discharge,
38 is a regulator for the hydraulic pump 37, and 3.9 is a pilot pump which is a hydraulic pressure source for pilot pressure.

40 is a solenoid valve, 41 is a solenoid of the solenoid valve 40, 42 is a pressure switch, and 43 is a controller.

In addition, when the hydraulic excavator performs work, the directional control valve (24
, 26, 27, etc.), the hydraulic pump 37
The discharge pressure increases, but the negative control pressure downstream of the center bypass oil passage 44 decreases.

At the same time, the swash plate tilt angle (not shown) of the hydraulic pump 37 is automatically adjusted, and the pump discharge flow rate increases.

Next, the configuration of the hydraulic shock absorber control device according to the present invention will be explained in the first part.
Described in the figure. Piston part 2 of boom cylinder 21
The proximity sensor switch 23 detects that the cylinder 2 approaches the stroke end, and sends the detection signal from the proximity sensor switch 23 and the pressure signal of the pilot pressure to be applied to the directional control valve 24 for the boom cylinder 21 to the controller 43.
. On the other hand, a solenoid valve 40 is interposed in an oil passage communicating between the pilot pump 39 and the regulator 38 for the hydraulic horn 37, and the solenoid valve 40 is normally set at the cutoff oil passage position A. When the piston 22 of the boom cylinder 21 approaches the stroke enton, an output signal from the controller 43 is outputted to the electromagnetic valve 40 to reduce the pump discharge flow rate.

Next, the functions of the hydraulic shock absorber control device according to the present invention will be described. When the operating lever 32 of the remote control valve 31 is operated in the boom raising direction C, pilot pressure from the pilot pump 39 acts on the directional switching valve 24 via the pilot valve 34 and the pilot oil passages 35 and 36. Since the directional switching valve 24 is switched from the neutral position to the second position, the boom cylinder 21 is operated to extend. When the piston portion 22 of the boom cylinder 21 approaches the stroke end, the proximity sensor switch 2 provided on the boom cylinder 21
The detection signal from 3 is sent to controller 4 through electric line 45.
3 is input. At the same time, the pressure signal of the pilot pressure acting on the directional control valve 24 for the boom cylinder 21 is
It branches off from the pilot oil line 35 and is input to the controller 43 via an oil line 46, a pressure switch 42, and an electric line 47.

The controller 43 performs arithmetic processing based on the input signal, and outputs an output signal to the solenoid valve 40. Since the solenoid valve 40 switches from the cut-off oil passage position A to the open oil passage position, the pilot pressure from the pilot pump 39 is
Branching from the oil passage 48, there is an oil passage 49, a check valve 50, an oil passage 51, an opening oil passage position opening of the solenoid valve 40, oil passages 52, 53,
It then acts on the regulator 38 for the hydraulic pump 37. Therefore, the pump discharge flow rate of the hydraulic pump 37 decreases.

As described above, the hydraulic cylinder (boom cylinder 21
) When the piston portion approaches the stroke end, the impact in the stroke end region of the hydraulic cylinder can be alleviated.

Effects of the Invention In the conventional hydraulic shock absorber control device, the flow rate on the return side of the hydraulic cylinder is restricted when the piston portion of the hydraulic cylinder approaches the stroke end. Therefore, even when the hydraulic cylinder has reached its stroke end, the main pressure hydraulic pump discharges a large amount of unnecessary oil. Therefore, the excess amount of oil was immediately returned to the oil tank through a relief valve or the like. The energy loss was large and the oil temperature rose, which had a negative impact on the hydraulic circuit equipment.

However, the hydraulic buffer control device according to the present invention detects that the piston portion of the hydraulic cylinder approaches the stroke end, and in response to the detection signal, reduces the discharge flow rate of the hydraulic pump via the controller. Thereby, energy loss in the engine and hydraulic pump can be reduced, and an increase in oil temperature can be prevented.

Therefore, in a construction machine equipped with the hydraulic shock absorbing control device according to the present invention, the impact in the stroke end region of the hydraulic cylinder is alleviated, and the maintainability of the hydraulic equipment is improved, which is useful for energy saving.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a hydraulic shock absorbing control device according to the present invention, FIG. 2 is an overall side view of a hydraulic excavator, and FIG. 3 is a circuit diagram showing a conventional hydraulic shock absorbing control device. 5.21-111 boom cylinder (hydraulic cylinder)9.
22 Piston part 10.24, 26.27---------One-way switching valve 23------------- Proximity sensor switch (detector) 37 Oil pressure Pump 38 Regulator 39 Pilot pump 40-------------Solenoid valve 4
3 Patent application for controllers and above Toshiaki Sawara and Hachizu Shozu, representative of Hitoyutani Heavy Industries Co., Ltd.

Claims (2)

[Claims] (1) Hydraulic buffer control in which the hydraulic cylinder is provided with a detection means for determining the cylinder stroke, and the shock in the stroke end region of the hydraulic cylinder is alleviated at a position before the stroke end of the piston when the hydraulic cylinder is extended or contracted. A hydraulic system for construction machinery, characterized in that the device detects that a piston portion of a hydraulic cylinder approaches a stroke end, and reduces the discharge flow rate of a hydraulic pump via a controller in response to the detection signal. Buffer control device. (2) Hydraulic buffer control in which the hydraulic cylinder is provided with a detection means for determining the cylinder stroke, and the impact in the stroke end region of the hydraulic cylinder is alleviated at a position before the stroke end of the piston portion when the hydraulic cylinder is extended or contracted. The device detects that the piston portion of the hydraulic cylinder approaches the stroke end, and inputs the detection signal and a pressure signal of pilot pressure to be applied to the directional control valve when the hydraulic cylinder is operated; , a solenoid valve is interposed in the oil path that communicates the pilot pressure oil source and the hydraulic pump regulator, and the solenoid valve is normally set to the shutoff oil path position, and when the piston of the hydraulic cylinder approaches the stroke end. A hydraulic buffer control device for construction machinery, characterized in that the controller outputs an output signal to the electromagnetic valve to reduce pump discharge flow rate.