JPH06299575A - Hydraulic driving device of construction machine - Google Patents

Abstract

PURPOSE:To improve safety by a method wherein there are provided a switch for sensing the stoppage of a hydraulic pump motor, selective command switch, and storage battery, and when the motor is not operating, even if a maloperation occurs, the motor is not actuated and on the other hand if an attempt is made to drive the motor slightly, the motor can be actuated by the command switch. CONSTITUTION:A stop sensing switch 2 is provided for a motor 1 for driving hydraulic pumps 3, 4 which feed pressure oil to each actuator to sense a stop condition. And a selective command switch 24 and a storage battery 40 are provided for a switching device 39 for switching a circuit. When the motor 1 is not operating, even if one erroneously touches operation levers 31-36, the actuator is not actuated, and on the other hand, when the motor 1 is at standstill and if an attempt is made to operate the acuator slightly, the selective switch 24 is operated to drive the actuator by means of an accumulator 21. As a result, safety of operation can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive system which is provided in a construction machine such as a hydraulic excavator and which is suitable for preventing malfunctions after a prime mover is stopped.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic drive system for a hydraulic excavator, a prime mover, a main hydraulic pump driven by the prime mover, a traveling motor driven by pressure oil discharged from the main hydraulic pump, a swing motor, a boom cylinder, an arm. Actuators such as cylinders and bucket cylinders, a switching valve that controls the flow of pressure oil supplied from the main hydraulic pump to each actuator, an auxiliary hydraulic pump that is driven by a prime mover, and an electric that electrically detects an operator's operation command. An operation detecting means having a lever, a switching valve operating means for electrically controlling the pressure oil discharged from the auxiliary hydraulic pump to operate each of the switching valves, for example, an electromagnetic proportional pressure reducing valve, and an electric power to the electromagnetic proportional pressure reducing valve. And a control device that outputs a drive signal to the electromagnetic proportional pressure reducing valve in response to an operation signal from the power supply device and the electric lever described above. It is provided with a means.

Also, in this conventional hydraulic drive system, a pressure accumulator, that is, an accumulator is provided in a branch line branched from a line connecting the auxiliary hydraulic pump and the electromagnetic proportional pressure reducing valve. This is because if the electromagnetic proportional pressure reducing valve is operated as necessary even after stopping the prime mover, the corresponding switching valve is switched using the pressure oil from this accumulator as a hydraulic pressure source,
It is designed to drive the corresponding actuator. For example, when you want to drive the corresponding actuator to lower the working machine that is stopped in the air due to the stop of the prime mover to the ground, or prior to disassembling the hydraulic equipment, repeatedly reciprocating the switching valve This accumulator is utilized when it is desired to release the pressure oil in the pipeline connected to the actuator to the low pressure circuit.

[0004]

However, in the above-mentioned prior art, when an operator or the like accidentally touches the electric lever after stopping the prime mover, the pressure oil from the accumulator is applied to the drive portion of the corresponding switching valve. When supplied, this switching valve is switched, which may lead to a state in which the actuator can be operated. For example, as described above, when the working machine held in the air is lowered by gravity, it is not intended by the operator. There is a problem that can cause actuation of the actuator.

The present invention has been made in view of the above-mentioned situation in the prior art, and an object thereof is to erroneously touch the electric lever of the operation detecting means while the prime mover driving the main hydraulic pump is stopped. However, it is an object of the present invention to provide a hydraulic drive system for a construction machine in which the switching valve is not switched.

[0006]

To achieve this object, the present invention provides a prime mover, a main hydraulic pump driven by the prime mover, an actuator driven by pressure oil discharged from the main hydraulic pump, and A switching valve that controls the flow of pressure oil supplied from the main hydraulic pump to the actuator, an auxiliary hydraulic pump that is driven by the prime mover, and an operation detection unit that has an electric lever that electrically detects an operation command from an operator, A switching valve operating means for electrically controlling pressure oil discharged from the auxiliary hydraulic pump to operate the switching valve, a power supply device for supplying electric power to the switching valve operating means, and an operation signal from the operation detecting means. Control means for giving a drive signal to the switching valve operating means in accordance with
In a hydraulic drive device for a construction machine, comprising: a pressure accumulating means provided in a branch pipe branching from a pipe connecting the auxiliary hydraulic pump and the switching valve operating means, it is detected that the prime mover is in a stopped state. Stop detection means, the switching valve operating means, and a circuit that connects the power supply device to each other, and an opening and closing means that can open and close the circuit, an opening operation command that opens the opening and closing means, and the opening and closing. Selection command means for selectively inputting one of the closing operation commands for closing the means, and a stop detection signal output from the stop detection means and a command signal output from the selection command means. Accordingly, the drive of the opening / closing means is controlled.

[0007]

Since the present invention has the above-described structure, when the prime mover driving the main hydraulic pump is in a stopped state,
For example, when the operator wants to drive the actuator according to his or her intention, the operator selects a closing operation command to drive the opening / closing means by the selection command means, connects the power supply device and the switching valve operation means, and operates the operation detection means. It suffices to operate the switching lever operating means by operating the electric lever of. As a result, the pressure oil of the pressure accumulating means is given to the drive portion of the corresponding switching valve via the switching valve operating means, and the actuator corresponding to the switching valve becomes operable. Therefore, when the actuator is connected to, for example, a working machine held in the air, the actuator is driven by the weight of the working machine and the working machine can be lowered.

When the operator does not intend to drive the actuator when the prime mover driving the main hydraulic pump is in a stopped state, the stop detection signal of the prime mover output from the stop detecting means causes The opening / closing means is driven so as to open, the connection between the power supply device and the switching valve operating means is cut off, and the prime mover is held in a stopped state. Therefore, at this time, even if the operator accidentally touches the electric lever of the operation detecting means, the pressure oil of the pressure accumulating means is not supplied to the drive portion of the switching valve via the switching valve operating means, that is, the switching valve is operated. Remains neutral without being switched, and the corresponding actuator is not activated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a hydraulic drive system for a construction machine of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The first embodiment shown in FIG. 1 shows a hydraulic drive system for a hydraulic excavator, which includes a prime mover 1 and a main hydraulic pump 3 driven by the prime mover 1.
4, an actuator such as a right traveling motor, a bucket cylinder, a boom cylinder, an arm cylinder, a swing motor, an attachment cylinder, a left traveling motor, etc., which are driven by pressure oil discharged from the main hydraulic pumps 3, 4, and a main hydraulic pump Switching valves 8 to 16 for controlling the flow of pressure oil supplied from the actuators 3 and 4 to the above actuators are provided. These switching valves 8 to 16 are respectively the above-mentioned unillustrated right traveling motor, bucket cylinder, boom cylinder, arm cylinder, swing motor, arm cylinder,
It is provided by assigning it to the boom cylinder, attachment cylinder, and left travel motor.

Further, the operation detecting means 31 to 36 for detecting the operation amount of the electric lever for switching the switching valves 8 to 16 described above, that is, the operation command of the operator and outputting the operation signal.
An auxiliary hydraulic pump 7 driven by the prime mover 1, and a switching valve operating means for electrically controlling the pressure oil discharged from the auxiliary hydraulic pump 7 to operate each of the switching valves 8 to 16.
For example, the electromagnetic proportional pressure reducing valves 27 and 28 that output the secondary pressure obtained by reducing the pressure oil from the auxiliary hydraulic pump 7 to drive the switching valves 8 and 9 respectively, and the electromagnetic proportional pressure reducing valve 29 that drives the switching valves 10 and 14, An electromagnetic proportional pressure reducing valve 30 for driving the switching valves 11 and 13 is provided.

Further, the auxiliary hydraulic pump 7 and the electromagnetic proportional pressure reducing valves 27, 28, 29, 30 which are the switching valve operating means described above.
The accumulator 21, which is provided in a branch line branched from the line that connects the same and the like, a stop detection unit that detects that the prime mover 1 is in a stopped state, for example, a stop command switch 2, and the above-mentioned electromagnetic Proportional pressure reducing valve 27-30
Power supply device for supplying electric power for driving the storage device, such as the storage battery 4
0, an opening / closing means 39 provided on a circuit connecting the storage battery 40 and the electromagnetic proportional pressure reducing valves 27 to 30 and the like, capable of opening / closing the circuit, an opening operation command for opening the opening / closing means 39, and An operation from the operation detection means 31 to 36, which has a selection command means for selectively inputting one of the closing operation commands for closing the opening / closing means 39, for example, the selection command switch 24, and a logic judgment function. The control means 38 outputs a drive signal to the electromagnetic proportional pressure reducing valves 27 to 30 in response to the signal.

Numerals 5 and 6 are main hydraulic pumps 3 and 3, respectively.
4 is a pump operating means for controlling the displacement volume of No. 4. As shown in FIG. 2, the above-mentioned opening / closing means 39 includes, for example, a relay 391 provided between the stop command switch 2 and the electromagnetic proportional pressure reducing valve 27, the selection command switch 24, the electromagnetic proportional pressure reducing valve 27, and the like. A relay 392 provided between them is provided.

The operation of the thus constructed first embodiment is as follows. That is, when the command signal for stopping the prime mover 1 is not output from the stop command switch 2 and the prime mover 1 is in the driving state, the main hydraulic pumps 3 and 4 are driven, and the main hydraulic pumps 3 and 4 are driven. Is supplied to the center bypass passages of the switching valves 8-16. In this state, when any one of the electric levers of the operation detecting means 31 to 36 is operated, a corresponding operation signal is output to the control means 38, and the control means 38 drives the corresponding electromagnetic proportional pressure reducing valves 27 to 30 and the like. The signal is output. As a result, the pressure oil of the auxiliary hydraulic pump 7 is given to the drive portion of the corresponding switching valve via any of the corresponding electromagnetic proportional pressure reducing valves 27 to 30 and the corresponding switching valve is switched. At this time, as the spool stroke of the switching valve increases, the openings of the passage connecting the pump port of the switching valve to the actuator port and the passage connecting the actuator port of the switching valve to the tank port gradually increase. The opening of the throttle that opens and closes the center bypass passage becomes smaller, and the flow rate of the flow into or out of the corresponding actuator and the flow direction of the pressure oil are adjusted accordingly, and the corresponding actuator described above. It operates at a speed corresponding to the amount of operation of the electric lever.

In such a driving state of the prime mover 1,
When a command signal (OFF signal) for stopping the prime mover 1 is output from the stop command switch 2, the prime mover 1 is stopped, the drive of the main hydraulic pumps 3 and 4 is accordingly stopped, and the operation of the actuator is stopped. , The working machine connected to this actuator is held stationary. At this time, the output of the OFF signal of the stop command switch 2 described above causes
The contact of the relay 391 of the opening / closing means 39 shown in (3) opens, and the electromagnetic proportional pressure reducing valve 27 and the like become operable only in response to the ON operation of the selection command switch 24.

That is, when the prime mover 1 is in such a stopped state and ON is selected by the selection command switch 24 and the closing operation of the opening / closing means 39 is selected, the contact of the relay 392 is closed and the electromagnetic proportional pressure reducing valve. 27 and the like are in an operable state. Therefore, by operating any one of the electric levers of the operation detecting means 31 to 36, the corresponding electromagnetic proportional pressure reducing valve 27 or the like is driven, and the pressure oil of the accumulator 21 is supplied to the driving portion of the corresponding switching valve, The switching valve can be switched, and the actuator corresponding to the switching valve can be put into an operable state. Here, for example, if the actuator is a boom cylinder and the working machine including the boom connected to the boom cylinder when the prime mover 1 is stopped is held stationary in the air, the electromagnetic proportional pressure reducing valve 2
The switching valves 10 and 14 are switched by operating 9, and the boom cylinder is operated by the weight of the working machine, so that the working machine can be lowered.

In addition, when the prime mover 1 is in the stopped state and the selection command switch 24 is set to OFF and the opening / closing means 39 is selected to open, the contact of the relay 392 is opened and the electromagnetic proportional pressure reducing valve. 27 and the like are in a neutral return state in which they cannot operate. Therefore, even if any one of the electric levers of the operation detecting means 31 to 36 is erroneously touched in such a state, the switching valves 8 to 16 are not switched, the respective actuators do not operate, and the work machine is not operated. Is kept stationary. That is, it is possible to reliably prevent the actuator from being operated unintended by the operator.

Even when the prime mover 1 is stopped without the operator's intention, such as when the prime mover 1 fails or is stopped due to overload, the selection command switch 24 is turned off and the opening / closing means 39 is opened. By the command, the electromagnetic proportional pressure reducing valve 27 and the like are brought into an inoperable neutral return state, and accordingly, the corresponding switching valves 8 to 16 are returned to the neutral state, and the operation of the corresponding actuator can be reliably prevented.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention, and FIG. 4 is an electric circuit diagram showing the construction of the opening / closing means portion shown in FIG. In the second embodiment, a generator 41 is provided integrally with the prime mover 1, and as shown in FIG. 4, this generator 41, like the storage battery 40, is an electromagnetic proportional pressure reducing valve 27-3.
It constitutes a power supply device that supplies electric power to 0 and the like. Also,
The wiring connecting the generator 41 and the opening / closing means 39 is the generator 1
The output voltage detecting means for guiding the output of the motor is formed, and instead of the stop command switch 2 of the first embodiment, the output voltage detecting means constitutes a stop detecting means for detecting that the prime mover 1 is in a stopped state. There is. Other configurations are the same as those in the first embodiment.

In the second embodiment, when the prime mover 1 is driven, electric power from the generator 1 is supplied to the electromagnetic proportional pressure reducing valves 27 and the like via the opening / closing means 39, and these electromagnetic proportional pressure reducing valves 27 and the like are operated. It remains operational. Therefore, when the drive signal corresponding to the operation amount of the electric lever such as the operation detection unit 31 is output from the control unit 38 to the drive unit such as the electromagnetic proportional pressure reducing valve 27, the corresponding electromagnetic proportional pressure reducing valve 27 operates. Pressure oil from the auxiliary hydraulic pump 7 is applied to the drive part of the corresponding switching valves 8 to 16 via the corresponding electromagnetic proportional pressure reducing valve 27, etc., and the switching valves 8 to 16 are switched to drive the corresponding actuator. You can

Further, when the prime mover 1 is stopped, the supply of electric power from the generator 41 provided in the prime mover 1 to the opening / closing means 39 is stopped, and the electromagnetic proportional pressure reducing valve 27 and the like are also provided as in the first embodiment. Becomes an operable state only in response to the ON operation of the selection command switch 24. Therefore, when the prime mover 1 is in such a stopped state, the selection command switch 24
When N is selected, the contact of the relay 392 is closed, the electromagnetic proportional pressure reducing valve 27 and the like are in an operable state, and one of the electric levers of the operation detecting means 31 and the like is operated,
The corresponding electromagnetic proportional pressure reducing valve 27 or the like is driven, the pressure oil of the accumulator 21 is supplied to the drive portion of the corresponding switching valve, the switching valve can be switched, and the actuator corresponding to the switching valve can be operated. Can be in a state. Further, when the prime mover 1 is stopped and the selection command switch 24 is set to OFF, the relay 39
When the contact of No. 2 is opened, the electromagnetic proportional pressure reducing valve 27 and the like are brought into the neutral return state in which the operation is inoperable, and the switching valves 8 to 16 are operated even if any of the electric levers such as the operation detecting means 31 is accidentally touched. There is no switching and each actuator is inactive, keeping the implement stationary.

Even in the second embodiment constructed as described above, when one of the electric levers such as the operation detecting means 31 is erroneously touched while the prime mover 1 is stopped, as in the first embodiment. However, the switching valves 8 to 16 are not switched,
It is possible to reliably prevent the operation of the actuator not intended by the operator.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention. In the third embodiment, as the stop detection means for detecting that the prime mover 1 is in a stopped state, the rotation speed detection for detecting the rotation speed of the prime mover 1 instead of the stop command switch 2 in the first embodiment described above. Means 37 are provided. In the third embodiment, the control means 38 has the operation detecting means 3
1 to 36 output signals for driving the corresponding electromagnetic proportional pressure reducing valves 27 to 30 in response to the operation command signals output from them, and open / close means 39 in response to the rotation speed signal output from the rotation speed detection means 37. Then, a signal for controlling the open state or the closed state is output. Other configurations are the same as those in the first embodiment.

In the third embodiment, the control means 3
In FIG. 8, the rotation speed signal output from the rotation speed detecting means 37 is read, and it is determined whether or not the value of the rotation speed signal is less than or equal to a predetermined value at which the prime mover 1 is considered to be non-driven. If this determination is not satisfied, the prime mover 1 is in a driving state, a signal for exciting the relay 391 of the opening / closing means 39 shown in FIG. 2 and closing the contact is output from the control means 38, and the electromagnetic proportional pressure reducing valve 27 and the like are turned on. Ready to operate. Here, when an electric lever such as the operation detection means 31 is operated, a drive signal corresponding to the operation amount of the electric lever is output from the control means 38 to the electromagnetic proportional pressure reducing valve 27 and the like, and the pump operation means 5 and 6 are also combined. A drive signal having the required capacity is output to the corresponding switching valve 8
16 can be switched to drive the corresponding actuator.

When the above-mentioned determination by the control means 38 is satisfied, the prime mover 1 is in the non-driving state and the selection command switch 24 is non-selected, that is, OFF.
It is determined whether or not. If this judgment is not satisfied,
The selection command switch 24 is ON, and the electromagnetic proportional pressure reducing valve 27 and the like are in an operable state. Thereby, the operation detecting means 31
By appropriately operating the electric levers No. 36 to No. 36, the pressure oil of the accumulator 21 is given to the drive unit of the corresponding switching valves 8 to 16, and the corresponding switching valves 8 to 16 are switched.
For example, when the prime mover 1 is stopped, it is possible to realize the operation of the actuator intended by the operator who wants to lower the work machine that was held stationary in the air.

When the selection command switch 24 described above is not selected, that is, whether the selection command switch 24 is OFF, the connection between the storage battery 40 and the electromagnetic proportional pressure reducing valve 27 is cut off and the electromagnetic proportional pressure reducing valve 27 is disconnected. Etc. become inoperable and in a neutral state. Therefore, even if the electric lever is accidentally contacted, the electromagnetic proportional pressure reducing valve 27 does not operate and the switching valve 8
~ 16 are not switchable and do not result in actuator actuation not intended by the operator.

In the above embodiment, the prime mover 1 is used as a stop detecting means for detecting that the prime mover 1 is in a stopped state.
Stop command switch 2 for instructing stop of the engine, output voltage detecting means of the generator 41 provided in the prime mover 1, and the prime mover 1
Although the rotation speed detecting means 37 for detecting the rotation speed of the main hydraulic pumps 3 and 4 and the auxiliary hydraulic pump 7 is detected as the stop detecting means, the present invention is not limited thereto. The pressure detecting means may be provided.

[0027]

Since the hydraulic drive system for a construction machine according to the present invention is constructed as described above, when the prime mover for driving the main hydraulic pump is stopped, the switching valve operating means is erroneously touched. Even at this time, the switching valve is not switched, and it is possible to reliably prevent the operation of the actuator which is not intended by the operator and which has conventionally occurred.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a hydraulic drive system for a construction machine according to the present invention.

FIG. 2 is an electric circuit diagram showing a configuration of an opening / closing means portion shown in FIG.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is an electric circuit diagram showing a configuration of an opening / closing means portion shown in FIG.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 1 prime mover 2 stop command switch (stop detection means) 3 main hydraulic pump 4 main hydraulic pump 5 pump operating means 6 pump operating means 7 auxiliary hydraulic pump 8 to 16 switching valve 21 accumulator (pressure accumulating means) 22 check valve 24 selection command switch (Selection command means) 27-30 Electromagnetic proportional pressure reducing valve (switching valve operation means) 31-36 Operation detection means 37 Rotation speed detection means (stop detection means) 38 Control means 39 Opening / closing means 391 Relay 392 Relay 40 Storage battery 41 Generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gen Yasuda, 650 Kintatemachi, Tsuchiura City, Ibaraki Prefecture, Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. (72) Inventor, Kazuyoshi Narita, 650 Kintate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd.

Claims (8)

[Claims] 1. A prime mover, a main hydraulic pump driven by the prime mover, an actuator driven by pressure oil discharged from the main hydraulic pump, and a flow of pressure oil supplied from the main hydraulic pump to the actuator. Switching valve, an auxiliary hydraulic pump driven by the prime mover, an operation detecting means having an electric lever for electrically detecting an operation command of an operator, and a hydraulic oil discharged from the auxiliary hydraulic pump are electrically controlled. Switching valve operating means for operating the switching valve, a power supply device for supplying electric power to the switching valve operating means, and control means for giving a drive signal to the switching valve operating means in response to an operation signal from the operation detecting means. ,
In a hydraulic drive system for a construction machine, comprising: a pressure accumulating means provided in a branch line branched from a line connecting the auxiliary hydraulic pump and the switching valve operating means, it is detected that the prime mover is in a stopped state. Stop detection means, and a switching means provided on a circuit connecting the switching valve operating means and the power supply device, capable of opening and closing the circuit,
A stop command output from the stop detection unit is provided, and a selection command unit for selectively inputting either an opening operation command for opening the opening / closing unit or a closing operation command for closing the opening / closing unit. A hydraulic drive system for a construction machine, characterized in that driving of the opening / closing means is controlled according to a detection signal and a command signal output from the selection command means. 2. The hydraulic drive system for a construction machine according to claim 1, wherein the stop detection means is stop command means for instructing stop of the prime mover. 3. The hydraulic drive system for a construction machine according to claim 1, wherein the stop detection means is a rotation speed detection means for detecting the rotation speed of the prime mover. 4. The hydraulic drive for a construction machine according to claim 1, wherein the stop detection means is pressure detection means for detecting a discharge pressure of at least one of the main hydraulic pump and the auxiliary hydraulic pump. apparatus. 5. The hydraulic drive system for a construction machine according to claim 1, wherein the stop detection means is an output voltage detection means of a generator provided in the prime mover. 6. The switching valve operating means is a pressure reducing valve for outputting a secondary pressure obtained by reducing the pressure oil from the auxiliary hydraulic pump to the switching valve, according to any one of claims 1 to 5. A hydraulic drive system for a construction machine according to 1. 7. The hydraulic drive system for a construction machine according to claim 1, wherein the power supply device is a storage battery provided in the prime mover. 8. The power supply device is a generator and a storage battery provided in the prime mover, and the power supply device is a storage battery.
A hydraulic drive system for a construction machine according to any one of 1.