JP3064520B2 - Working oil amount switching control device for hydraulic excavator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention sometimes employs a hydraulic breaker or the like as an attachment in place of a bucket normally mounted as a working machine of a hydraulic excavator to perform a work of crushing a structure, a block or the like. Especially in the case of breaker work performed with a small amount of oil for normal drilling work,
By setting the breaker mode, load sensing control of the hydraulic pump is performed and the optimal oil amount is set.
The present invention relates to a working oil amount switching control device for a hydraulic excavator, wherein an engine for driving a hydraulic pump is driven at a rotation speed at which fuel consumption is reduced.

[0002]

2. Description of the Related Art In some cases, a hydraulic breaker or the like is attached as an attachment in place of a bucket normally used as a working machine of a conventionally used hydraulic excavator to perform a work of crushing a structure, a block or the like. However, since the oil amount close to half of the excavation operation is sufficient in the breaker operation, the capacity V (cc / re) of the hydraulic pump is reduced as shown in the engine torque diagram shown in FIG.
v) constant (absorption torque T of the hydraulic pump is represented by T = kP * V, where k is a proportional constant and P is a load pressure.
The absorption torque T0 of the hydraulic pump is constant for a constant load pressure) and the engine speed for driving the hydraulic pump is set to N
1, N2, N3 (rev / min) to control the amount of oil required for the breaker work, that is, VN1, VN2, V
N3 (cc / min) was controlled.

[0005] Further, as shown in FIG. 5, a merge switching circuit for two hydraulic pumps is provided, and one of two service valves is switched to switch the flow rate of one pump ← → two pumps to perform excavation work. And the amount of oil required for each of the breaker operations. In FIG. 6, five switching valves for driving the actuators for turning, boom Hi, service arm Lo, and left running are connected in parallel to a variable displacement hydraulic pump (hereinafter referred to as a main pump) 31, respectively. The main pump 32 is connected in parallel with five switching valves for driving actuators for right traveling, bucket, boom Lo, arm Hi, and service. The two pipes 34 and 35 connected to the outlet port of the service valve 33 in FIG. 5 are connected to hydraulic circuits from the service valve 36 on the left side to an actuator 37 such as a breaker, so that they merge. A pedal 38 for operating an attachment such as a breaker abuts a pilot pressure control valve (hereinafter, referred to as a PPC valve) 39,
The control pump 40 is used as a hydraulic pressure source. The PP
One of the two pilot circuits 41 and 42 coming out of the C valve 39 is connected to the left end of the service valve 36, and the other is connected to the right end. The pilot circuit 4
1 and 42 are provided with branch circuits 43 and 44, respectively.
The service valve 33 is connected to the right end and the left end via pilot circuit switching valves 45 and 46 each having a solenoid. The solenoids of the pilot circuit switching valves 45 and 46 are connected to a switching switch 46, respectively.

[0004] During normal excavation work or the like, the actuator 37
When the switch 46 is operated to the ON side when the flow rate for two pumps is required, the pilot circuit switching valve 45 is operated.
The 46 solenoids are excited and the pilot circuit 41
By operating the pedal 38, the pilot pressure acts on the left end of the service valve 36 and the right end of the service valve 33.
And the left end of the service valve 33.
Thus, the total flow rate of the main pumps 31 and 32 acts on the actuator 37 that drives the attachment. When the hydraulic breaker work is performed by the actuator 37, only the flow rate for one pump is required, so the changeover switch 46 is operated to the OFF side. As a result, the solenoids of the pilot circuit switching valves 45 and 46 are demagnetized,
The branch circuits 43 and 44 of the pilot circuits 41 and 42 are closed, and the pilot pressure acts only on the left end or the right end of the service valve 36 by operating the attachment pedal 38. Thus, only the flow rate of the main pump 1 acts on the actuator 37 that drives the hydraulic breaker.
In addition, the main pump discharge amount is controlled in accordance with the movement of each switching valve spool, and in particular, the main pump discharge amount is controlled to a minimum when each switching valve is in the neutral position, so that the main pump discharge amount is reduced. A relief valve 47 and an orifice 48 are provided in the circuit, and these and the flow rate adjusting mechanism 49 of the main pump 32 are connected by a circuit to control the discharge amount of the main pump.

[0005]

However, in the method of controlling the engine speed as shown in FIG. 4 to reduce the amount of oil necessary for the breaker work and the fuel efficiency of the engine, a predetermined load pressure, that is, a hydraulic pressure With respect to the pump absorption torque T0, the engine speed is reduced so as to be at points A1, A2 and A3, and the discharge amount of the hydraulic pump is reduced so that the oil amount required for the work is reduced. However, the points A1, A2, and A3 move outward from the center of the iso-fuel efficiency diagram (center is 100%) indicated by B, so that the fuel efficiency of the engine is reduced. It was difficult to reduce the fuel consumption of the engine.

The flow rate switching circuit shown in FIG. 5 has the following problems. (1) Two pilot circuit switching valves 4 in the pilot circuit
5.46 must be provided and the service valve 33
Requires two pipes 34 and 35 to join the main circuit of the attachment actuator 37. This complicates the hydraulic circuit, reduces the reliability of the hydraulic excavator, increases the number of inspection and maintenance steps, and increases the manufacturing cost. (2) The amount of oil supplied to the attachment actuator is two-stage switching between one pump and two pumps.
The flow rate cannot be finely adjusted. The present invention focuses on the above-described conventional problems, and in a breaker operation or the like performed with a small amount of oil for a normal excavation operation, the hydraulic pump is load-sensing controlled by setting a breaker mode to optimize an oil amount. And an engine for driving the hydraulic pump is driven at a rotation speed at which fuel consumption is reduced.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the prior art, and a first aspect of the present invention is to provide a variable displacement hydraulic pump, an engine for driving the hydraulic pump, An actuator driven by a hydraulic pump, an operation valve interposed in a pipeline between the hydraulic pump and the actuator, a load sensing control device of the hydraulic pump, a work mode switching device, and a switching signal from the work mode switching device And a controller for outputting a fuel injection amount signal to the governor driving device of the engine and a differential pressure signal upstream and downstream of the operation valve to the load sensing control device. The controller sets the first engine fuel setter and the first load sensing differential pressure in response to a switching signal from the work mode switching device. To output a first engine fuel setting signal from the first engine fuel setting device to the engine fuel signal generator, and to output a first load sensing differential pressure setting signal to the first load sensing differential pressure. The second engine fuel setting signal is output from the setter to the load sensing differential pressure signal generator, or the second engine fuel setter and the second load sensing differential pressure setter are operated to output the second engine fuel setting signal to the second engine fuel setting signal. Outputting a second load sensing differential pressure setting signal from the second load sensing differential pressure setter to the load sensing differential pressure signal generator while outputting the second load sensing differential pressure setting signal from the engine fuel setter to the engine fuel signal generator; The fuel injection amount signal from the fuel signal generator is sent to the governor drive of the engine, and the load sensing differential pressure signal generator is sent to the load sensor. And outputting a first engine fuel setting device and a first load sensing differential pressure setting device or a second engine fuel setting device in the controller according to the second embodiment. One of the pressure sensor and the second load sensing differential pressure setting device is omitted, and instead, the engine fuel injection amount of the engine and the load sensing differential pressure of the load sensing control device are preset. A control device for switching a working oil amount in a hydraulic excavator. According to a fourth aspect of the present invention, the load sensing control device according to the first and second aspects includes a displacement control cylinder of the hydraulic pump and a load sensing control valve for supplying a hydraulic pressure to the displacement control cylinder, wherein the load sensing control valve is operated by the load sensing control valve. The capacity of the hydraulic pump is reduced by increasing the pressure difference upstream and downstream of the valve, the capacity of the hydraulic pump is increased by reducing the pressure difference upstream and downstream of the operating valve, and the load sensing differential pressure signal is increased by increasing the load sensing differential pressure signal. The capacity of the hydraulic pump is reduced, and the capacity of the hydraulic pump is increased by decreasing the load sensing differential pressure signal.

[0008]

According to the above construction, the following operation is performed. When the hydraulic excavator drives an actuator such as a breaker that requires a relatively small amount of oil, when the work mode switching device is switched to the low horsepower mode, the controller controls the governor drive device of the engine to reduce the fuel consumption. Since the injection amount signal is output, the engine horsepower is reduced, and a differential pressure signal that reduces the differential pressure upstream and downstream of the actuator operation valve is output to the load sensing control device. The capacity of the variable displacement hydraulic pump is reduced with respect to the quantity. Accordingly, the displacement of the variable displacement hydraulic pump decreases per unit time because the capacity of the variable displacement hydraulic pump decreases and the engine speed for a predetermined torque decreases due to the decrease in the engine horsepower. Also, when driving an actuator that requires a relatively large flow amount of oil, such as for excavation work, when the work mode switching device is switched to the high horsepower mode, a high fuel injection amount signal is sent from the controller to the governor drive device of the engine. As the output is increased, the engine horsepower is increased, and a differential pressure signal that reduces the differential pressure upstream and downstream of the actuator operation valve is output to the load sensing control device. The capacity of the variable displacement hydraulic pump increases. Accordingly, the displacement of the variable displacement hydraulic pump increases per unit time because the capacity of the variable displacement hydraulic pump increases and the engine speed for a predetermined torque increases due to the increase in the engine horsepower.

According to a second aspect, when the controller according to the first aspect receives a switching signal from the work mode switching device, the first engine fuel setting device and the first engine fuel setting device are controlled by the switching signal.
Of the load sensing differential pressure setter, or the second engine fuel setter and the second load sensing differential pressure setter are activated. When the first setters are activated, the first
The engine fuel setting signal is output to the engine fuel signal generator, and the first load sensing differential pressure setting signal is output to the first load sensing differential pressure signal generator.
When the second setting devices are operated, a second engine fuel setting signal is output to the engine fuel signal generator, and the second load sensing differential pressure setting signal is output to the second load sensing differential pressure signal generator. And outputs a fuel injection amount signal from the engine fuel signal generator to a governor driving device of the engine and a load sensing differential pressure signal from the load sensing differential pressure signal generator to the load sensing control device.

According to a third aspect of the present invention, when a switching signal is input from the operation mode switching device, the engine fuel injection amount set in advance is set in the operation mode which is omitted from among the setting units in the controller of the second aspect. The governor is driven as described above, and the load sensing control device also has a preset load sensing differential pressure. In the operation mode of the setting device in the controller of the second aspect, which is not omitted, the operation is the same as that of the second aspect. According to a fourth aspect of the present invention, the load sensing control device according to the first and second aspects includes a displacement control cylinder of the hydraulic pump and a load sensing control valve that supplies a hydraulic pressure to the displacement control cylinder, and is operated to decelerate the actuator. When the valve is throttled, the pressure difference between the upstream and downstream of the operation valve increases, so that the capacity of the hydraulic pump is reduced and wasteful power is reduced. Further, when the opening of the operating valve is increased to increase the speed of the actuator, the pressure difference between the upstream and downstream of the operating valve is reduced, so that the capacity of the hydraulic pump is increased to supply a required flow rate. For the same operation amount of the operation valve, when the load sensing differential pressure signal is increased, the capacity of the hydraulic pump is reduced, the discharge amount of the hydraulic pump per unit time is reduced, and the load sensing differential pressure signal is reduced. If it is decreased, the capacity of the hydraulic pump increases and the discharge amount of the hydraulic pump per unit time increases.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a diagram showing an embodiment of a control circuit according to the present invention, FIG. 2 is a diagram showing details of a controller in FIG. 1, and FIG. 3 is a diagram showing an iso-absorption torque curve of a hydraulic pump. 1 and 2, reference numeral 1 denotes an engine, 1
a is a governor driving device of the engine 1; 2 is a hydraulic pump driven by the engine 1; 3 is a breaker; 4 is pipes 5a and 5 connecting the hydraulic pump 2 and the breaker 3;
b, a breaker operating valve for operating the breaker operating valve 4; 6, a pilot operating valve for generating a pilot pressure corresponding to the operation amount of the breaker operating lever 6a; Swash plate 2a of the hydraulic pump 2
, A spring provided in the bottom chamber 7b of the capacity control cylinder 7 for urging the piston 7d in the direction of the rod chamber 7c, and a piston 7e for connecting the piston 7d to the swash plate 2a. The rod 8 is a load sensing valve for switching the control pressure of the displacement control cylinder 7, the solenoid 8a is a solenoid of the load sensing valve 8 connected to the controller 10, and the load 8b is a load connected to the upstream pipe 5a of the operation valve 4. The pilot cylinder of the sensing valve 8, 8 c is the pilot cylinder of the load sensing valve 8 connected to the downstream pipe 5 b of the operation valve 4, 8 d is the differential pressure setting spring of the load sensing valve 8, and 9 is the control pressure of the displacement control cylinder 7. A control pump 10 as a source receives a switching signal from a work mode switching device, and controls a governor driving device 1 of the engine 1. A fuel injection amount signal and the controller that outputs a differential pressure signal control valve upstream and downstream to the solenoid 8a of the load sensing valve 8 of the load sensing control device, the controller 10 engine fuel setter 1
1, a load sensing differential pressure setting unit 12, 14, an engine fuel signal generator 15, and a load sensing differential pressure signal generator 16. Reference numerals 17 to 23 denote work mode switching devices, 17 is a power supply, 18 is a work mode switch button including an excavation mode button S, a breaker mode button B, return springs 18a and 18b, 19 is a magnet, 20 is a spring,
21 is a work mode changeover switch, 22 is a self-holding switch, 23 is a spring, and 24 is a tank. FIG. 3 shows an iso-absorption torque diagram TB of the breaker 3 and an iso-absorption torque diagram TS of a digging actuator (not shown) drawn on a hydraulic pump displacement V-pressure P plane.

Next, the operation of the configuration shown in FIGS. 1 to 3 will be described. When the hydraulic excavator is to be operated in the normal excavation mode, when the excavation mode button S of the operation mode switching button 18 is pressed, the magnet 19 is demagnetized because the voltage of the power supply 17 is not applied to the magnet 19 and the operation is performed. The mode switch 21 is connected to the contact A by a spring 20. Accordingly, since the voltage of the power supply 17 is applied to the engine fuel setting device 11 and the load sensing differential pressure setting device 12 in the controller 10, the high engine fuel setting signal HS set by the engine fuel setting device 11 generates the engine fuel signal. The high load sensing differential pressure setting signal set by the load sensing differential pressure setting device 12 is output to the differential pressure signal generator 16. The engine fuel signal generator 15 is an increasing function generator, and outputs an engine fuel signal ih corresponding to the high engine fuel setting signal from the controller 10 to the governor driving device 1a of the engine 1, thereby increasing the engine horsepower. The load sensing differential pressure signal generator 16 is a decreasing function generator, and outputs a low load sensing differential pressure signal ip corresponding to the high load sensing differential pressure setting signal ΔPs from the controller 10 to the solenoid 8a of the load sensing valve 8. The load sensing valve 8 moves in the direction of the a position to move the capacity control cylinder 7.
Since the hydraulic oil in the bottom chamber 7b is drained, the capacity of the hydraulic pump 2 increases. As described above, in the excavation mode, the operation is performed at a high engine speed and a high hydraulic pump capacity, so that the hydraulic pump discharge amount per unit time increases and each actuator operates at a high speed to improve work efficiency. Can be.

Next, when the breaker mode button B of the work mode switching button 18 is pressed to drive a sufficient breaker with a relatively small amount of oil, the power source 1 is supplied to the magnet 19.
Since the voltage of 7 is applied, the magnet 19 is excited,
Self-holding switch 2 even if breaker mode button B is released
Since 2 is held at the C contact, the magnet 19 holds the excitation, and the work mode changeover switch 21 continues to be connected to the contact B against the spring 20. Accordingly, since the voltage of the power supply 17 is applied to the engine fuel setting device 13 and the load sensing differential pressure setting device 14 in the controller 10, the low engine fuel setting signal Hb set by the engine fuel setting device 13 is used.
Is output to the engine fuel signal generator 15 and the low load sensing differential pressure setting signal ΔPb set by the load sensing differential pressure setting device 14 is output to the differential pressure signal generator 16. As described above, the engine fuel signal generator 15 is an increasing function generator, and outputs the engine fuel signal ih corresponding to the low engine fuel setting signal Hb from the controller 10 to the governor driving device 1a of the engine 1 so that the engine horsepower is reduced. I do. The load sensing differential pressure signal generator 16 is a decreasing function generator, and the low load sensing differential pressure setting signal Δ
The high load sensing differential pressure signal ip corresponding to Pb is transmitted from the controller 10 to the solenoid 8 of the load sensing valve 8.
When output to a, the load sensing valve 8 moves in the direction of the b position and hydraulic oil is supplied from the control pump 9 to the bottom chamber 7b of the displacement control cylinder 7, so that the capacity of the hydraulic pump 2 decreases. As described above, in the breaker mode, the engine is operated with low engine speed and low hydraulic pump capacity,
The discharge amount of the hydraulic pump per unit time can be reduced.

The first controller 10
Either one of the engine fuel setting device 11 and the first load sensing differential pressure setting device 12 or the second engine fuel setting device 13 and the second load sensing differential pressure setting device 14 is omitted. The engine fuel injection amount of the engine 1 and the load sensing differential pressure of the load sensing control device may be set in advance. Each setting device 11, 12, or 13, in the controller 10,
When a switching signal is input from the work mode switching device when any one of 14 is omitted, in the work mode not omitted, the operation is the same as that of the embodiment, but in the work mode omitted, The governor is driven so as to have a preset engine fuel injection amount, and the load sensing control device also has a preset load sensing differential pressure.

[0015]

As described in detail above, according to the present invention, the following effects can be obtained. (1) The change of the working oil amount by changing the work mode can be easily performed by the mode changeover switch. (2) A plurality of operation modes are enabled by switching the operation mode. However, since the capacity of the hydraulic pump is adjusted by load sensing control and the engine horsepower can be set independently of the capacity adjustment of the hydraulic pump, In the working mode, the required flow rate can be guaranteed, and the fuel efficiency of the engine can be reduced. (3) Load sensing control of the capacity of the hydraulic pump,
Since the operation valve can be controlled in a wide operation range, the operability of the operator can be improved.

[0016]

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a control circuit according to the present invention.

FIG. 2 is a diagram showing details of a controller in FIG. 1;

FIG. 3 is a diagram showing an equal absorption torque curve of an actuator driven by an engine.

FIG. 4 is a diagram showing adjustment of an oil amount of a hydraulic pump by rotation of an engine in a conventional technique.

FIG. 5 is a diagram showing adjustment of an oil amount by a merging switching circuit of a plurality of hydraulic pumps in the related art.

[Explanation of symbols]

 Reference Signs List 1 engine 1a governor driving device 2 variable displacement hydraulic pump 2a swash plate 3 breaker 4 breaker operating valve 5a upstream pipeline 5b downstream pipeline 6 pilot operated valve 6a breaker operating lever 7 capacity control cylinder 7a spring 7b bottom chamber 7c rod chamber 7e Piston rod 8 Load sensing valve 8a Solenoid 8b Pilot cylinder 8c Pilot cylinder 8d Differential pressure setting spring 9 Control pump 10 Controller 11,13 Engine fuel setting device 12,14 Load sensing differential pressure setting device 15 Engine fuel signal generator 16 Load sensing differential Pressure signal generator 18 Work mode switch button 18a, 18b Return spring 20, 23 Spring 19 Magnet 21 Work mode switch 22 Self-holding switch 24 Tank

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02F 9/22

Claims (4)

(57) [Claims] 1. A variable displacement hydraulic pump, an engine for driving the hydraulic pump, an actuator driven by the hydraulic pump, an operation valve interposed in a pipeline between the hydraulic pump and the actuator, and the hydraulic pump A load sensing control device, a work mode switching device, a switching signal from the work mode switching device, a fuel injection amount signal to a governor driving device of the engine, and the load control signal to the load sensing control device. A control device for switching a working oil amount in a hydraulic excavator, comprising a controller that outputs an upstream and downstream differential pressure signal. 2. A first engine fuel setting signal according to claim 1, wherein the controller operates the first engine fuel setting device and the first load sensing differential pressure setting device in response to a switching signal from the work mode switching device. Is output from the first engine fuel setter to the engine fuel signal generator, and a first load sensing differential pressure setting signal is output from the first load sensing differential pressure setter to the load sensing differential pressure signal generator. Or operating a second engine fuel setter and a second load sensing differential pressure setter to output a second engine fuel set signal from the second engine fuel setter to the engine fuel signal generator. And a second load sensing differential pressure setting signal from the second load sensing differential pressure setting device. And outputs the engine fuel injection amount signal from the engine fuel signal generator to the governor driving device of the engine and the load sensing differential pressure signal from the load sensing differential pressure signal generator to the load sensing control device. A control device for switching a working oil amount in a hydraulic excavator. 3. The controller of claim 2, wherein the first engine fuel setter and the first load sensing differential pressure setter, or the second engine fuel setter and the second load sensing differential pressure setter. A working oil amount switching control device for a hydraulic excavator, characterized in that one of them is omitted and the engine fuel injection amount of the engine and the load sensing differential pressure of the load sensing control device are set in advance. 4. The load sensing control device according to claim 1, wherein the load sensing control device comprises a displacement control cylinder of the hydraulic pump and a load sensing control valve for supplying a hydraulic pressure to the displacement control cylinder. The capacity of the hydraulic pump is reduced by increasing the pressure difference upstream and downstream of the operating valve, the capacity of the hydraulic pump is increased by reducing the pressure difference upstream and downstream of the operating valve, and the load sensing differential pressure signal is increased. A working oil amount switching control device for a hydraulic excavator, wherein a capacity of the hydraulic pump is reduced, and a capacity of the hydraulic pump is increased by decreasing the load sensing differential pressure signal.