JPH11125217A - Hydraulic driving device for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out warming-up safely in a short time without giving a fatigue to an operator. SOLUTION: In the hydraulic driving device for a construction machine which supplys a pressure oil from a variable displacement hydraulic pump 2 to actuators 4a, 4b through flow control valves 5a, 5b controlled by electromagnetic control valves 6a, 6b, the device is equipped with a switch to command a warming-up mode; a warming-up command quantity storing means which makes this switch 10 cooperate with an operation detecting means for storing a command quantity toward the electromagnetic control valves 6a, 6b; and a warming up operation signal outputting means for outputting a command quantity signal stored in the warming up command quantity storing means to the electromagnetic control valves 6a, 6b in the neutral state of an operating lever.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive device for a construction machine that drives an actuator with the pressure oil of a variable displacement hydraulic pump.

[0002]

2. Description of the Related Art A conventional hydraulic drive for a construction machine of this type uses hydraulic oil from a hydraulic pump as an actuator when the working environment is a cold region or immediately after the start of a motor. The hydraulic fluid in the pilot circuit that drives the flow control valve that selectively supplies the hydraulic fluid to the main hydraulic circuit that operates the above actuators does not warm up, and the temperature of the hydraulic fluid is low. Sex was impaired.

[0003]

In order to improve the operability at low temperatures, conventionally, an operator operates the actuator until the stroke end, then keeps the operation lever at the stroke end, and circulates the hydraulic oil under high pressure. I had to keep going and was getting tired.

In the prior art disclosed in Japanese Patent Publication No. 64-2810, the temperature of hydraulic oil is raised by relief of a main valve, and the pressure oil is caused to flow into a pilot pump circuit by using a switching valve. Although the pilot circuit is warmed up, this method requires a switching valve, and the operator needs to keep holding the operation lever until the pressure oil of the main valve is warmed, so that the operability is poor.

Further, the technique disclosed in Japanese Patent Publication No. 2-35164 is provided with a means for supplementarily applying pilot pressure by a switch, whereby the switching valve is forcibly made non-neutral, and the pilot circuit is provided. Is also warming up.
However, in this method, since the operation lever is not interlocked, when the operator tries to stop the work machine at an emergency in a danger, or when the cylinder of the actuator reaches the stroke end, the pressure oil is relieved and the noise is noisy. When there is a complaint from the local residents, it is necessary to find and turn off the switch.

At a work site, there are a plurality of operators,
When an operator different from the operator who turned on the warm-up switch is operating, when the operation is to be stopped, it is usual to move the operating lever of the working machine shaft,
Unless the location of the warm-up switch is known, the warm-up operation cannot be stopped easily.

The present invention has been made in view of the above, and a controller stores a control command based on information generated by operating an operation lever or a switch, or replaces a previously stored command value with a control value. While the hydraulic oil warms up,
Alternatively, during the installation time or for a period desired by the operator, the operator can continue to output without operating the operation lever, and can stop the warm-up operation based on the information of the operation lever or switch, and can operate the main hydraulic circuit. It is an object of the present invention to provide a hydraulic drive device for a construction machine capable of performing a warm-up operation of hydraulic oil in various directions of a pilot circuit without giving a fatigue to an operator and safely and in a short period of time. Things.

[0008]

In order to achieve the above object, a hydraulic drive system for a construction machine according to the present invention comprises: a prime mover; a variable displacement hydraulic pump driven by the prime mover;
A pilot pump driven by a prime mover, an actuator for driving a working machine, etc., a flow control valve disposed between the hydraulic pump and the actuator, and a flow control valve for reducing pressure oil from the pilot pump An electromagnetic control valve for switching operation, an operation lever, operation detection means for detecting at least the presence or absence of operation of the operation lever, and a signal for switching the flow control valve to the electromagnetic control valve based on a signal from the operation detection means And a switch for commanding a warm-up mode,
A warm-up command amount storing means for storing a command amount to the electromagnetic control valve in conjunction with the switch and the operation detecting means, and a command amount signal stored in the warm-up command amount storing means when the operating lever is in a neutral state. Is output to the electromagnetic control valve. In this configuration, by operating the operation lever and the switch, the command amount by the operation of the operation lever in the warm-up mode is stored,
By operating the switch again, the stored operation lever signal is output as a flow control valve operation signal. Therefore, the warm-up operation in the warm-up mode can be performed by the operator without operating the operation lever, and the warm-up operation of the hydraulic oil can be performed safely in a short time without giving the operator fatigue. be able to.

In the above arrangement, only the presence or absence of an operation of the operation lever or an operation member in place of the operation lever is detected, and a switch is similarly operated according to the detected value, and the value stored in advance by the controller is obtained. The same operation and effect can be obtained by outputting to the electromagnetic control valve.

In the hydraulic drive system for a construction machine according to the present invention, the warm-up mode is released in such a manner that the warm-up mode is released by operating one of an operation lever and a switch during the warm-up operation. With the provision of the means, the warm-up mode is released by operating either the operation lever or the switch.

At this time, means for detecting the oil temperature of the pilot circuit for driving the flow control valve and means for detecting the oil temperature of the main hydraulic circuit for driving the actuator are provided. By adding
When the hydraulic oil warms up, the control of the warm-up operation can be automatically stopped. Further, in addition to the provision of the oil temperature detecting means, the controller is provided with a state of storing the output elapsed time of the control signal, and the control of the warm-up operation can be automatically stopped after the elapsed time.

Further, in the hydraulic drive system for a construction machine according to the present invention, a stroke end detecting means for detecting a stroke end of the actuator is provided, and the actuator can be switched to the warm-up mode only at the end of the stroke. According to this, only when it is determined that the actuator is at the stroke end, the warm-up operation is controlled. Thus, the actuator can always be brought into the stroke end state during the warming-up operation, and it is possible to eliminate the danger of an operational sensation during the warming-up operation and unnecessary operation of the working machine.

Further, according to the hydraulic drive system for a construction machine according to the present invention, the output of the control signal stored in the warm-up command amount storage means is repeatedly output _{in a} wave form such as a Sin wave from its maximum value to zero. As a result, the set value set for the warm-up operation control is repeatedly output in a wave form from zero to the maximum value, whereby the opening area of the flow control valve is reduced from zero to a predetermined size. , The hydraulic oil passing through the flow control valve is repeatedly throttled, and the temperature of the spool in the flow control valve is increased by the frictional heat at that time, so that the warm-up operation time can be shortened.

[0014]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of a hydraulic drive device of a construction machine, which includes a prime mover 1, a variable displacement hydraulic pump 2 driven by the prime mover 1, a pilot pump 3 driven by the prime mover 1, and a working machine. A plurality of actuators 4a, 4b to be driven, and main hydraulic circuits connecting the hydraulic pump 2 and the actuators 4a, 4b are arranged.
a, flow control valves 5a, 5b for selectively supplying to a, 4b,
Electromagnetic control valves 6a, 6b for switching the flow rate control valves 5a, 5b by reducing the pressure oil from the pilot pump 3, and potentiometers 8a, 8b for outputting electric signals corresponding to the operation amounts of the operation levers 7a, 7b. And a signal based on the signals from the potentiometers 8a and 8b.
a, 9b for outputting to the controller 9a, 6b
And a switch 10 for inputting ON and OFF of the warm-up mode. The relief valve 11 is connected to the main hydraulic circuit. Reference numeral 12 denotes a pump displacement machine for controlling the displacement of the hydraulic pump 2.

The control of the controller 9 by the switch 10 is as follows. First, in order to set the warm-up mode, the operation levers 7a, 7
b) and then return to neutral with this switch ON. During this time, the controller 9 stores the maximum value as lmax.

On the other hand, there is no potentiometer 8a, 8b for detecting the operation amount of the operation lever shown in FIG. 1, and as shown in FIG. 2, a pressure reducing valve for reducing the pilot pressure in accordance with the operation amount of the operation levers 7a, 7b. Equipped with 20a, 20b,
In the case where the respective flow control valves 5a and 5b are switched by the pressure, the respective flow control valves 5a and 5b are switched.
Are provided with pressure switches 21a and 21b for detecting the pilot pressure of the pilot circuits, and the operation of the operation levers 7a and 7b is detected based on the information.

The control of the controller 9 by the switch 10 operates the operation levers 7a and 7b while the switch 10 is turned on, and then returns the switch to the neutral state while the switch is turned on. When the operating levers 7a and 7b are operated, pressure is generated in the pilot line by the pressure reducing valves 20a and 20b.
By detecting at 1b, the operation lever axis is detected, and a preset value is stored as lmax.

Next, when the switch 10 is turned off while the operation levers 7a and 7b are in the neutral state, the controller 9 is turned off.
Directly outputs lmax stored as described above to the electromagnetic control valves 6a and 6b as a warm-up mode command. That is, when the warm-up mode command is being output, the operation levers 7a and 7b are in a neutral state.

As described above, when the warm-up mode signal is output from the controller 9, the flow control valves 5a and 5b are switched to one communication position via the electromagnetic control valves 6a and 6b, and the pressure from the hydraulic pump 2 is changed. Oil is supplied to the actuators 4a, 4b, which are actuated until the end of the stroke. Subsequent pressure oil is drained from the relief valve 11, and high-pressure oil pressure is circulated to raise the temperature of the hydraulic oil.

In the warm-up mode, the operation levers 7a,
By operating the switch 7b or turning on the switch 10, the warm-up mode is released and the output of the warm-up mode command from the controller 9 is stopped. The above operation is performed by one of a plurality of operation levers. Even if the warm-up operation is performed using one operation lever, it is safe if the stop of the warm-up operation is performed by operating the other operation lever. The switch 10 may be a push button type switch 10 provided at the tip of one of the operating levers 7a and (7b). According to this, the switch 10 can be operated by the same hand while operating the operation levers 7a and (7b). The algorithm of the warm-up mode operation of the single lever lever is as shown in FIG.

Since the amount of heat generated by the circulation of the hydraulic oil is determined by the product of the pressure and the flow rate of the hydraulic oil, the electromagnetic control valves 6a and 6b operate to apply pilot pressure to the flow control valves 5a and 5b. Warm up pilot circuit (heating)
Is promoted. At the same time, warming-up (heating) of the hydraulic oil is promoted.

The hydraulic circuit shown in FIG. 1 has an operation lever 7a,
A positive control (position control) type in which the discharge amount of the hydraulic pump 2 is determined according to the operation amount of the pump 7b, in this case, the relationship between the operation amounts of the operation levers 7a and 7b and the displacement of the pump is as shown in FIG. Therefore, by outputting the stored signal of the operation command of the warm-up mode to the pump displacement device 12 from the controller 9, the pump displacement device 12 is controlled in a predetermined manner, the pump discharge amount is increased, and the warm-up operation is performed. Done.

This operation is the same even if the hydraulic pump is a negative control (negative control) type or a load sensing type. In other words, in the case of a negative control hydraulic circuit as shown in FIG. 5, operating the flow control valve 13 in a non-neutral direction requires the spool to determine the amount of outflow to the neutral circuit 14 inside the flow control valve 13. Since the stroke is increased, the stroke of the flow control valve 13 and the opening of the neutral circuit 14 have a relationship as shown in FIG. 6, so that the neutral opening is reduced, and the flow into the circuit communicating with the actuator is reduced. The opening increases and the outflow to the neutral circuit decreases. The pump control of the negative control is performed so that the oil after leaving the neutral circuit has a relationship between the differential pressure before and after the oil has passed through the throttle 15 in front of the tank and the pump displacement as shown in FIG. Therefore, if the stroke of the spool of the flow control valve 13 is increased to close the neutral opening area, the amount of oil flowing through the throttle 15 is reduced, and the differential pressure across the throttle 15 is reduced. The displacement is increased to increase the pump discharge amount, and the operating oil is also warmed up.

In the case of the load sensing type, operating the flow control valve in a non-neutral direction opens the inflow opening, that is, causes a large amount of oil to flow through the actuator, and as a result, the load on the actuator is reduced. The pressure increases, the difference between the pump pressure and the load pressure decreases, and in load sensing that controls the pump displacement to maintain the difference between the pump pressure and the load pressure as shown in FIG. 8, the pump displacement increases. As a result, the pump discharge amount increases, and the warm-up is performed similarly.

In the above-described series of controls, if the flow control valve is switched in the warm-up mode in a state where the actuator is not at the stroke end, the actuator performs a stroke operation to the stroke end and then stops only after reaching the stroke end. In other words, the work implement has been activated up to that time, and the operator does not operate the operation levers 7a and 7b at that time.

In order to prevent this, a means for detecting the stroke end of the actuator is provided, and a control signal is output when it is determined that the actuator for driving the working machine of the operating shaft is at the stroke end. Good. FIG. 9 shows the algorithm at this time.

There are several means for detecting the stroke end of the actuator. First, if a stroke sensor for detecting the stroke of the actuator is mounted, it is possible to easily judge the stroke end based on the information. Further, as shown in FIG. 10, and input the signals R ₁ if Sonaere a potentiometer for detecting the rotation angle with the rotation axis 16 of the working machine controller 9, the stroke end of the actuator 4a is seen by the signal R ₁ Therefore, it is possible to determine whether or not the actuator 4a that drives the working machine of the operation axis is at the stroke end.

FIG. 11 shows the signal R _{1 in the} configuration shown in FIG.
And the stroke of the actuator 2. Further, in the apparatus shown in FIG. 1, a pressure sensor P for detecting a pump pressure or an inflow pressure to an actuator is provided and a signal thereof is inputted to a controller, and a relief pressure is set to 300 kgf.
/ Cm ² , the pressure detected by the pressure sensor P is 300
When the weight becomes close to kgf / cm ² , the stroke end may be determined. The pressure sensor P at this time may be provided anywhere between the hydraulic pump and the actuators 4a and 4b.

Then, as the stop determination information, FIG.
In addition to the hydraulic circuit shown in, as shown in FIG. 13, the flow control valve 5a, the main hydraulic circuit operating the second oil temperature sensor T ₂ and actuators for detecting the oil temperature of the pilot circuit for controlling driving 5b comprising a first oil temperature sensor T ₁ for detecting the oil temperature, by incorporating the oil temperature information of the sensors T _1, T ₂ to the controller 9, as a means of stopping the control signals are output, the operation described above That is, (1) the operation levers 7a and 7b are moved. (2) Press the switch 10. In addition to the operation, (3), the first oil temperature sensor T ₁ is higher than the set value. (4) a second oil temperature sensor _{T 2} is higher than the set value. If any one of the conditions is satisfied, the warm-up operation is stopped to prevent energy loss.

In addition to the means for providing the oil temperature sensors T ₁ and T ₂ , the controller 9 is provided with a mechanism for storing the elapsed time of the output of the control signal. If the control is stopped at this point, it can be used as a simple control stopping means.

The controller 9 outputs the output signal lmax
If the maximum value is set to 0 to lmax and a sine wave, a cos wave, or a rectangular wave is repeatedly output, the spool for determining the openings of the flow control valves 6a and 6b is increased from zero to MAX.
The drive is repeatedly performed up to the value, whereby heat is generated by friction due to movement, and it is possible to effectively warm up. The algorithm at this time is shown in FIG.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive device to which the present invention is applied.

FIG. 2 is a perspective view showing an operation lever having a switch.

FIG. 3 is a flowchart illustrating an algorithm for a single lever lever according to the present invention.

FIG. 4 is a diagram showing a pump displacement with respect to an operation lever operation amount.

FIG. 5 is a hydraulic circuit diagram of a negative control type.

FIG. 6 is a diagram showing an opening area of a flow control valve with respect to a spool stroke.

FIG. 7 is a diagram showing a pump displacement with respect to a differential pressure across a throttle of a negative control hydraulic circuit.

FIG. 8 is a diagram showing a pump displacement with respect to a difference between a pump pressure and a load pressure.

FIG. 9 is a flowchart showing an algorithm when a warm-up operation is performed at the stroke end of the actuator.

FIG. 10 is an explanatory diagram illustrating an example of a unit that detects a rotation angle of a work machine.

FIG. 11 is a diagram illustrating an actuator stroke with respect to a rotation angle of a work machine.

FIG. 12 is a flowchart showing an algorithm when a signal for operating the flow control valve is output in a wave shape.

FIG. 13 is a hydraulic circuit diagram of a hydraulic drive device to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Hydraulic pump 3 ... Pilot pump 4a, 4b ... Actuator 5a, 5b ... Flow control valve 6a, 6b ... Electromagnetic control valve 7a, 7b ... Operating lever 8a, 8b ... Potentiometer 9 ... Controller 10 ... Switch 12 ... Pump Displacement device 13 ... Flow control valve 14 ... Neutral circuit 15 ... Throttle 16 ... Rotating shaft 20a, 20b ... Pressure reducing valve 21a, 21b ... Pressure switch

Claims (4)

[Claims] 1. A motor, a variable displacement hydraulic pump driven by the motor, a pilot pump driven by the motor, an actuator for driving a working machine and the like, and a hydraulic pump and an actuator A flow control valve to be disposed, an electromagnetic control valve for switching the flow control valve by reducing the pressure oil from the pilot pump, an operation lever, and operation detection means for detecting at least the presence or absence of operation of the operation lever; A switch for commanding a warm-up mode, comprising: a switch for commanding a warm-up mode; and a controller for outputting a signal for switching a flow control valve to an electromagnetic control valve based on a signal from the operation detecting means. A warm-up command amount storage means for storing a command amount to the electromagnetic control valve in conjunction with the means; and Hydraulic drive system for a construction machine, characterized in that the command variable signal and a warm-up operation signal output means adapted to output to the solenoid control valve. 2. The hydraulic drive system for a construction machine according to claim 1, further comprising a warm-up mode canceling means for canceling the warm-up mode by activating one of an operation lever and a switch during the warm-up operation. A hydraulic drive for a construction machine. 3. The hydraulic drive device according to claim 1, wherein
A stroke end detecting unit that detects a stroke end that detects a stroke end of the actuator,
A hydraulic drive device for a construction machine, wherein an actuator can be switched to a warm-up mode only at a stroke end. 4. A hydraulic drive system for a construction machine according to claim 1, the output of the control signal stored in the warm-up command value memory, repeating the wavy S _{i n} waves and the like over zero from its maximum value output A hydraulic drive device for a construction machine, wherein