JPH11117914A - Hydraulic driving device for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability by providing a hydraulic pump circuit with a pressure relief bleed valve, and setting the pressure of a hydraulic pump by a pumping pressure setting means according to the value detected by an oil temperature detecting means for detecting the temperature of operating fluid. SOLUTION: A controller 8 controls the opening area of a bleed valve 5 according to a signal from an oil temperature sensor 6, that is, according to the temperature of operating fluid and holds pumping pressure to high pressure to increase the generated quantity of heat. In the neutral state of a lever, a hydraulic pump 1 discharges the fixed flow of oil. Accordingly, when bleed opening is determined, corresponding pumping pressure can be obtained. The bleed opening and pumping pressure are therefore in the relation of one to one correspondence. At this time, the upper limit of set pumping pressure is set to relief pressure or less. Pumping pressure does not therefore reach relief pressure, so that oil is not relieved from a relief valve, and therefore there is no relief noise. The set pressure is variably and continuously controlled, for instance. Pumping pressure is therefore lowered as oil temperature rises from low temperature, and operation can be performed without a sense of incongruity.

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 a plurality of actuators with hydraulic oil from a hydraulic pump.

[0002]

2. Description of the Related Art In a conventional hydraulic pump for construction equipment, as represented by a so-called load sensing circuit and a negative control (negative control) circuit, in the former, the difference between the maximum load pressure of the actuator and the pump pressure is kept constant. As described above, the latter has been controlled based on information on the flow rate or the pressure passing through a neutral circuit (center bypass circuit). That is, the lever operation of the directional control valve becomes a switch, and the displacement of the hydraulic pump is determined so as to match this lever operation feeling.

[0003]

When the surrounding environment is in a cold region or immediately after the start of the prime mover, the viscosity of the hydraulic oil increases because the temperature of the hydraulic oil is low, and the operability is impaired. Had been.

In order to improve the operability at a low temperature, in the technique disclosed in Japanese Patent Publication No. 4-32247, the warming-up of the prime mover and the working oil is performed separately in a negative control system. However, in this method, it is necessary to separately provide a switching valve that constitutes a relief valve control means in a normal negative control system, and a variable throttle valve that reduces the negative control pressure accordingly. Since it is performed separately, it takes time to complete both warm-ups.
The pressure oil increased due to the warm-up is discharged using a relief valve. For this reason, the pump pressure has risen to the relief pressure, which is efficient for warming up, but the noise from the relief valve, which relieves at high pressure, is large, which is not good for the surrounding environment.

Another conventional technique is Japanese Patent Publication No. 7-6896.
According to the technology disclosed in Japanese Patent Application Publication No. 6-36, the pump displacement at low temperature is increased by a load sensing circuit, and the oil temperature is increased by the throttle loss generated by the unload valve. In this case, the control is performed by the unload valve. The maximum pressure is 3
Since it is about 0 kgf / cm ² , the warm-up operation is mainly performed when the operation lever is set to neutral. When the maximum load pressure at that time is 0 kgf / cm ² , the pump pressure is 30 kgf / cm 2.
Only about ^two .

[0006] Similarly, a load sensing circuit disclosed in Japanese Utility Model Laid-Open No. 5-16851 discloses a pump control in which a pump pressure is introduced instead of an LS pressure (highest load pressure line pressure) at a low temperature in pump control. Although the volume is a full swash plate, the discharge rate is increased and the warm-up is promoted,
In this case as well, the pump pressure is either a pressure that can be controlled by the unload valve or, if there is no unload valve, the set pressure of the relief valve, which is not preferable for warm-up operation.

In the technology disclosed in Japanese Utility Model Publication No. Hei 5-37041 and Japanese Utility Model Publication No. Hei 5-37042, the pressure for operating the pump regulator is set between the throttle of the neutral circuit and the pump regulator in the negative control system. Although a switching valve for switching is provided, in this method, when the pump discharge amount is increased when the hydraulic oil is warmed up, the pump displacement device always reaches the maximum position, so that the load is excessively applied. Stalls may occur, or the pump regulator may be broken at low temperatures by abruptly moving the pump regulator to the full swash plate. Further, since no means for keeping the pump pressure high is not provided, it is not possible to effectively warm up the hydraulic oil.

The present invention has been made in view of the above. When the temperature of hydraulic oil is low, the pressure of the pump is controlled to a pressure equal to or lower than the relief pressure, and the displacement of the pump is increased to increase the hydraulic oil. It is an object of the present invention to provide an oil drive system for a construction machine in which operability is improved by raising the temperature of the vehicle in a short time with low noise.

[0009]

In order to achieve the above object, a hydraulic drive system for a construction machine according to claim 1 of the present invention comprises a prime mover and a variable displacement hydraulic drive driven by the prime mover. A hydraulic drive device for a construction machine comprising a pump, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a pump displacement device for setting a displacement of the hydraulic pump, A bleed valve to release the pressure of the pump circuit,
It comprises an oil temperature detecting means for detecting the temperature of the hydraulic oil, and a pump pressure setting means for setting the pressure of the hydraulic pump according to the value detected by the oil temperature detecting means.

The pump pressure setting means for setting the pressure of the hydraulic pump in accordance with the value detected by the oil temperature detecting means according to the first aspect of the present invention comprises a maximum pressure of the bleed valve in accordance with the value detected by the hydraulic pressure detecting means. Bleed valve opening setting means for setting the opening.

In these constructions, the pressure of the hydraulic pump or the maximum value of the opening of the bleed valve is controlled in accordance with the temperature of the hydraulic oil, the pump pressure is maintained at a high pressure, and heat is generated by oil escaping from the bleed valve. . By setting the upper limit of the set pump pressure at this time to be equal to or less than the relief pressure, the pump pressure does not reach the relief pressure, and therefore oil does not escape from the relief valve, so that relief noise can be eliminated. Further, by controlling the pump pressure continuously according to the oil temperature, for example, by variably setting the set pressure, the pump pressure decreases as the oil temperature increases from a low temperature, so that the steering can be performed without discomfort.

According to a third aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. A flow control valve for selectively supplying a hydraulic pump, a pump displacement device for setting a displacement of the hydraulic pump, a pump pressure detecting means for detecting a hydraulic pump circuit pressure, and a brute valve for releasing the pressure of the hydraulic pump circuit. In a hydraulic drive device of a construction machine, an oil temperature detection unit that detects a temperature of hydraulic oil, a pump pressure setting unit that sets a pump pressure that sets a pressure of a hydraulic pump according to a value detected by the oil temperature detection unit, The pump pressure control means controls the opening of the breat valve by the pump pressure setting means. In this configuration, since the pump pressure detecting means is provided in the configuration of the first aspect, the pump pressure detected by the pump pressure detecting means is fed back, so that accurate pump pressure control is performed. Can be.

According to a fourth aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. A bleed valve for releasing the pressure of a hydraulic pump circuit, a bleed valve for releasing the pressure of a hydraulic pump circuit, a motor water temperature, an air temperature, or a pressure control valve for selectively supplying a flow control valve and a pump displacement device for setting a displacement of a hydraulic pump. Temperature detecting means for detecting any of the hydraulic oil temperatures, time measuring means for detecting the passage of time after the start of the prime mover, and time setting means for setting the opening time of the bleed valve according to the detected value of the temperature detecting means. Consists of In this configuration, when an oil temperature sensor for detecting the temperature of the hydraulic oil cannot be attached, control can be performed using a water temperature sensor, an air temperature sensor, and a timer of the prime mover. The control may be performed using a combination of an oil temperature sensor and a timer.

According to a fifth aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. A bleed valve for releasing the pressure of a hydraulic pump circuit, a bleed valve for releasing the pressure of a hydraulic pump circuit, a motor water temperature, an air temperature, or a pressure control valve for selectively supplying a flow control valve and a pump displacement device for setting a displacement of a hydraulic pump. Temperature detecting means for detecting any of the hydraulic oil temperatures, time measuring means for detecting the passage of time after the start of the prime mover, and time setting means for setting the opening time of the bleed valve according to the detected value of the temperature detecting means. Bleed valve opening setting means for setting the maximum value of the bleed valve opening according to the value set by the time setting means, and the time detected by the time measuring means. Within an opening in the determined bleed valve time between setting means consist bleed valve control means for controlling the maximum opening of the bleed valve to a value set by the bleed valve opening setting means. According to this configuration, it is possible to satisfactorily manage the time of the warm-up operation by releasing the hydraulic oil from the bleed valve.

According to a sixth aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. In a hydraulic drive for a construction machine having a flow control valve for selectively supplying and a pump displacement device for setting a displacement of a hydraulic pump, an oil temperature detecting means for detecting a temperature of hydraulic oil; Lever operation amount detection means for detecting the operation amount,
The control table selecting means for comparing the control tables of the pump displacement units based on the respective detected values of the oil temperature detecting means and the lever operation amount detecting means and selecting the larger one, and the control table selecting means selected by the control table selecting means. And control means for controlling the pump displacement device by means of a control table. According to this configuration, the displacement volume of the pump can be controlled according to the required flow rate corresponding to the operation amount of the lever and the like. Then, the discharge amount is increased according to the oil temperature and the engine is warmed up. Therefore, the discharge amount can be increased without controlling the bleed valve. In addition, the operation of the actuator can be performed during the warm-up operation.

According to a seventh aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. In a hydraulic drive for a construction machine having a flow control valve to be selectively supplied, and a pump displacement device for setting a displacement of a hydraulic pump according to an operation amount of a lever, a water temperature of an engine, an outside air,
Temperature detecting means for detecting the temperature of any of the hydraulic oil, lever operating amount detecting means for detecting the operating amount of the operating lever, timer means for measuring the elapsed time after starting the motor, and the lever operating amount detection Control table selecting means for comparing the control table of the pump displacement device based on the respective detection values of the means and the temperature detecting means and selecting the larger one, and pump displacement by the control table selected by the control table selecting means. And control means for controlling the volumetric device within a set time corresponding to the detected value of the temperature detecting means. This configuration can be easily applied to a hydraulic drive device without an oil temperature sensor for detecting the operating oil temperature, in contrast to the configuration described in claim 7.

According to another aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. It has a flow control valve for selectively supplying and a pump displacement device for setting the displacement of the hydraulic pump, and controls the pump displacement device according to the difference between the pump pressure and the maximum load pressure of each actuator. In a hydraulic drive device of a construction machine, a load pressure detecting means for detecting a maximum load pressure of each actuator, a temperature detecting means for detecting any of a prime mover water temperature, an outside air or a hydraulic oil temperature, and a hydraulic oil temperature. Oil temperature detecting means for detecting, pressure generating means for generating a set maximum load line pressure corresponding to a value detected by the oil temperature detecting means, A pressure generated by means consist shuttle means for guiding the larger pressure detected by said load pressure detecting means to the maximum load pressure line of the actuator. According to this configuration, the pump pressure can be controlled continuously according to the oil temperature, and the pump pressure decreases as the oil temperature increases from a low temperature, so that the steering can be performed without feeling uncomfortable.

According to a ninth aspect of the present invention, there is provided a hydraulic drive system for a construction machine, comprising: a prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, and hydraulic oil from the hydraulic pump to the actuator. It has a flow control valve for selectively supplying and a pump displacement device for setting the displacement of the hydraulic pump, and controls the pump displacement device according to the difference between the pump pressure and the maximum load pressure of each actuator. In the hydraulic drive device of the construction machine, the load pressure detecting means for detecting the maximum load pressure of each actuator, the temperature detecting means for detecting any one of the prime mover water temperature, the outside air or the hydraulic oil temperature, and Timer means for measuring the elapsed time, time setting means for setting a time corresponding to the value detected by the temperature detecting means, and setting of the time setting means. A pressure setting means for setting a pressure according to the set time; and a pressure generating means for generating the pressure set by the pressure setting means if the time detected by the timer means is within the time set by the time setting means. Means, and shuttle means for guiding the greater of the pressure generated by the pressure generating means and the pressure detected by the load pressure detecting means to the highest load pressure line of the actuator. In this configuration, by introducing a pseudo maximum load line pressure other than the maximum load pressure of the actuator, the pump displacement can be increased and the pump pressure can be maintained at a high pressure by the unload valve even in the neutral state.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a control system of a construction machine according to the present invention. In the figure, reference numeral 1 denotes a variable displacement hydraulic pump driven by a prime mover 2, reference numeral 3 denotes a pump displacement device for setting the displacement thereof, and reference numeral 4 denotes a pump connected to an actuator via a flow control valve of the hydraulic pump 1. 5 is a relief valve for releasing when the pressure oil of the hydraulic oil of the discharge circuit becomes higher than a set pressure, 5 is a bleed valve for bleeding the pressure oil of the discharge circuit, 6 is an oil temperature sensor for detecting the temperature of the hydraulic oil, and 7 is This is a pressure sensor for detecting pump pressure. Reference numeral 8 denotes a controller for operating the bleed valve 5. The controller 8 receives detection signals from the oil temperature sensor 6 and the pressure sensor 7.
Although the oil temperature sensor 6 is installed in the hydraulic oil tank in the example shown in the figure, the oil temperature sensor may be located anywhere, such as a pump discharge port, where the temperature of the hydraulic oil is known.

In this control system, the controller 8
2, the opening area of the bleed valve 5 is controlled in accordance with the signal from the oil temperature sensor 6, that is, the temperature of the hydraulic oil, the pump pressure is maintained at a high pressure, and the amount of generated heat is increased. In the lever neutral state, the hydraulic pump 1 discharges a constant flow of oil. Therefore, when the bleed opening is determined, a pump pressure corresponding to the bleed opening is obtained. Therefore, as shown in FIG. Take a one-to-one relationship. At this time, if the upper limit of the set pump pressure is set to be equal to or less than the relief pressure, the pump pressure does not reach the relief pressure and the oil does not relieve from the relief valve 4, so that there is no relief noise.
Control for maintaining the discharge pressure of the hydraulic pump 1 at or above the set pressure is performed by control as shown in FIG. In a control system not using the pressure sensor 7 as shown in FIG.
The controller 8 determines the maximum value of the bleed opening of the bleed valve 5 according to the oil temperature as shown in FIG. 5, so that when the oil temperature is low, the bleed opening tends to close and the pressure of the hydraulic pump 1 is increased. Raise the calorific value.

If an oil temperature sensor for detecting the oil temperature of the hydraulic oil cannot be installed, a water temperature sensor or a temperature sensor of a radiator of a prime mover is provided instead of the oil temperature sensor.
If a timer and means for detecting the passage of time after the start of the prime mover are provided, as shown in FIG. 6, a set time is set for the water temperature and the air temperature. As shown, the pump pressure and the maximum value of the bleed opening may be determined and the pump pressure may be controlled to a predetermined pressure or more, or the maximum opening of the bleed valve 5 may be controlled. Further, as shown in FIG. 30, the maximum value of the bleed opening may be directly determined with respect to the water temperature. 9 and 10 are conceptual diagrams showing a control system in this case. In the figures, 9 is a water temperature sensor of the prime mover 2, 9a is a timer, and the controller 8 inputs signals from the water temperature sensor 9 and the timer 9a. Based on this, a bleed signal is output to the bleed valve 5. FIG.
1 is a conceptual diagram in a case where an air temperature sensor 9b is used instead of a water temperature sensor.

Also, in the oil temperature sensor system, a timer or the like may be provided similarly, and control similar to that shown in FIGS. 6, 7, and 8 may be performed. Alternatively, as a redundant system in the case where the oil temperature sensor 6 is broken, a system that stops the control if the set time is satisfied may be adopted.

FIG. 11 is a conceptual diagram showing a control system according to a second embodiment of the present invention, in which the pump displacement device 3 is controlled in accordance with a required flow rate corresponding to an operation amount of an operation lever and the like. I have. In the figure, reference numeral 10 denotes an actuator 11
The flow control valve 10 is configured to selectively supply the pressure oil from the hydraulic pump 1 to the hydraulic pump 1. The flow control valve 10 is switched by a pilot pressure from an electromagnetic proportional valve 12.

In the figure, reference numeral 13 denotes a potentiometer for outputting an electric signal proportional to the operation amount of the operation lever to the controller 8, and 14 denotes a pilot circuit which is provided in a pilot circuit connecting the electromagnetic proportional valve 12 and the pilot pump 15, and A source pressure safety switch 16 operated by a source pressure safety lever for turning on / off the source pressure of the circuit, and outputs a signal based on a signal from the potentiometer 13 to the electromagnetic proportional valve 12 to drive the flow control valve 12. Is a flow control valve controller for controlling the flow rate. Here, in addition to the signal from the potentiometer 13, signals from the oil temperature sensor 6 and the pressure sensor 7 are input to the controller 8, and control signals based on these signals are transmitted to the prime mover 2, the pump The signals are output to the displacement device 3 and the bleed valve 5, respectively.

In this control system, a method of controlling the pump pressure to be equal to or higher than the set pressure according to the oil temperature shown in FIG. 2 or the maximum value of the bleed opening corresponding to the oil temperature as shown in FIG. As a result, when the oil temperature is low, the bleed opening is slightly closed, and the pressure of the hydraulic pump 1 is increased. At this time, the pressure sensor 7 need not be provided.

Further, since this control system is a positive control (positive control), the displacement of the hydraulic pump 1 changes according to the lever operation amount.
As shown in FIG. 12, the controller 8 normally stores the relationship between the pump displacement for the operation lever and the pump displacement for the operation lever in accordance with the oil temperature. The pump displacement of whichever is larger is used as the command output. The control is as shown in FIG.

Alternatively, as shown in FIG. 14, the controller 8 has a map of the relationship between the pump displacement of the operating lever according to the oil temperature and the map displacement according to the map information according to the oil temperature. If the command signal is output, the amount of generated heat can be further increased by increasing the discharge amount. At this time, if the pump displacement command is limited and controlled so as not to exceed the absorption horsepower that the hydraulic pump 1 can output, no engine stall occurs.

As shown in FIG. 15, when the means (oil temperature sensor) for detecting the oil temperature of the hydraulic oil cannot be installed,
If a water temperature sensor 9 and a temperature sensor of the prime mover 2 are provided in place of the oil temperature sensor and a timer 9a for detecting the time elapsed after the start of the prime mover is provided, as shown in FIG. The pump displacement as shown in FIG. 16 is output as a command value within the set time.
Also, in the system of the oil temperature sensor, a timer or the like may be provided and the same control may be performed.

In the warm-up mode in the control system shown in FIG. 11, if the rotation of the prime mover 2 is similarly controlled, the warm-up can be performed more efficiently. That is, in the warm-up mode, as shown in FIG. 17, the controller 8 outputs a command signal for increasing the rotation speed of the prime mover according to the oil temperature.

As an example of an optimum warm-up operation, the displacement of the pump 2 is as large as possible, but the rotation of the prime mover 2 is such that the noise of the motor 2 does not matter, for example, the minimum (MIN)
A little higher than the rotation and pump pressure 2
If the warming-up is performed while maintaining the pressure at about 00 kgf / cm ² , the surrounding noise is reduced and the warming-up can be performed in a short time. Further, when it is desired to realize the warm-up mode with low fuel consumption, the rotation of the prime mover with the highest fuel consumption efficiency may be set.

FIG. 18 shows a load sensing control system according to a third embodiment of the present invention. In this figure, the same members as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the figure, 17 is an auxiliary pilot pump, 18 is a pressure reducing solenoid valve for reducing the pilot pressure from the auxiliary pilot pump 17 by a signal from the controller 8,
19 is a shuttle valve for selecting a larger pressure between the pilot pressure from the pressure reducing solenoid valve 18 and the maximum load pressure of the actuator. 20 is a shuttle valve for when the pump pressure becomes larger than the sum of the pressure guided by the shuttle valve 19 and the spring force. This is an unload valve that allows pressurized oil to flow into the tank. Although the oil temperature sensor 6 in the figure shows an example in which the oil temperature sensor is provided in the hydraulic oil tank, this may be anywhere as long as the hydraulic oil temperature can be detected.

In this control system, the controller 8 detects the operating oil temperature by the oil temperature sensor 6 and sets a set maximum load line pressure (LS pressure) according to the oil temperature of the operating oil shown in FIG.
It is generated by a pressure reducing solenoid valve 18 and guided to a shuttle valve 19. Now, when the operation lever is in a neutral state and the flow control valve is closed, the maximum load pressure line from the actuator is 0 kgf / cm ² , and the high pressure from the pressure reducing solenoid valve 18 is introduced to the final maximum load pressure line. I will

In the load sensing, as shown in FIG. 20, the pump displacement is such that the difference between the maximum load pressure and the pump pressure is αk.
gf / cm ² , so that the maximum load pressure (LS pressure) equal to or higher than (pump pressure −α) is
Assuming that it has entered 9, the pump is controlled to increase the displacement. And the spring force of the unload valve 20 is (α +
10) Assuming that the pressure is set at kgf / cm ² , the pump pressure is controlled to (set maximum load pressure + α + 10). Thereby, for example, the set maximum load pressure becomes 1
If the pressure is 00 kgf / cm ² , the pump pressure is 130 kgf / cm ^2.
/ Cm ² . In addition, the hydraulic pump 1 limits the maximum pump displacement device 3 that can output itself according to the pump pressure, so that engine stall does not occur.

When a device (oil temperature sensor) for detecting the oil temperature of the hydraulic oil cannot be installed, instead of the oil temperature sensor, a water temperature sensor or a temperature sensor of a radiator of the prime mover 2 and a timer or a time after starting the prime mover are used. If a means for detecting the progress is provided, a set time is provided for the water temperature as shown in FIG. 21, and within the set time, the set maximum load pressure is determined and the pressure reducing solenoid valve 18 is set as shown in FIG. What is necessary is to control. Also,
As shown in FIG. 32, the set maximum load pressure may be directly determined for the water temperature. Further, a timer or the like may be provided in a control system using an oil temperature sensor to perform similar control.

Then, as shown in FIG. 23, the controller 8 further controls the rotation of the prime mover 2 to
If it can be raised at the time of warm-up as shown in 7, it will be possible to output more flow while maintaining high pressure,
The calorific value can be increased.

When the warming-up control is completed based on information such as an oil temperature sensor, a timer, and means for detecting the lapse of time after the start of the prime mover, a buzzer or a lamp for notifying a person outside the vehicle of the completion of the control. If the operator turns on the key of the prime mover 2 after turning on the key of the prime mover 2, it is possible to know the end of the warm-up even if the operator is away from the vehicle and waiting in the cabin, so that the operator does not have to wait in the cold cabin. It is also possible to reduce operator fatigue. For example, a lamp is mounted on the upper part of the cabin of a vehicle, and the lamp is turned on during warm-up, and is turned off when the lamp ends.

Basically, the control for increasing the amount of generated heat is performed when the oil temperature is lower than the set temperature or when the operator does not move the working machine (when not operating), without impairing the operational feeling. Is not so complicated. As a result, if the information of the potentiometer 13 and the source pressure safety switch 14 and the information from the oil temperature sensor 6 are input to the controller 8 as determination information, and it is determined from the potentiometer 13 and the source pressure safety switch 14 that the vehicle is not in the steering state, ,
Even if the oil temperature has not reached the set temperature, if the control is stopped, the uncomfortable feeling due to an increase in the rotation of the motor 2 or an increase in the displacement of the pump can be eliminated. The control system at that time is shown in FIGS. 24 and 25 as a modified example of the second embodiment shown in FIGS.

Assuming that the signal of the potentiometer 13 is turned on by operating the operation lever and that the source pressure safety switch 14 of the source pressure safety lever is turned on by releasing the source pressure safety lever, as shown in FIG. When both signals of the safety switch 14 are OFF, the warm-up mode is controlled when the oil temperature of the working oil is lower than a predetermined temperature is set as the warm-up mode.

In the load sensing circuit shown in FIG. 27, reference numerals 21a and 21a denote pressure reducing valves for reducing the pilot pressure from the pilot pump 15 in accordance with the operation amount of the operation lever. Since there is no means for taking in the controller 8, the warm-up mode only needs to be performed using the information of the source pressure safety switch 14, as shown in FIG. If a pressure sensor or pressure switch for detecting the pilot pressure is provided, the information may be taken into the controller 8 as a lever signal and used as a signal instead of the potentiometer.

Further, by installing a pilot circuit for driving the flow control valve adjacent to the hydraulic oil tank or the flow control valve, the oil in the pilot circuit simultaneously rises in temperature as the hydraulic oil temperature rises. Can be done.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a control system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an oil temperature and a set pump pressure set by a bleed valve.

FIG. 3 is a flowchart showing the operation of a bleed valve.

FIG. 4 is a conceptual diagram illustrating a control system when there is no pressure sensor according to the first embodiment.

FIG. 5 is a diagram showing the relationship between the maximum values of the bleed valve openings according to the oil temperature.

FIG. 6 is a diagram showing a relationship between a water temperature, an oil temperature and a set time.

FIG. 7 is a diagram showing a relationship between a set pump and a set time.

FIG. 8 is a diagram showing a relationship between a set time and a maximum value of a bleed valve opening.

FIG. 9 is a conceptual diagram illustrating a control system when the oil temperature sensor according to the first embodiment is not used.

FIG. 10 is a conceptual diagram showing a control system when the oil temperature sensor and the pressure sensor according to the first embodiment are not used.

FIG. 11 is a conceptual diagram illustrating a control system according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between a pump displacement and a lever operation amount.

FIG. 13 is a flowchart showing the operation of controlling the displacement of the pump.

FIG. 14 is a diagram showing a relationship between a displacement of a pump and an operation amount of an operation lever according to an oil temperature.

FIG. 15 is a conceptual diagram illustrating a control system when the oil temperature sensor according to the second embodiment is not used.

FIG. 16 is a diagram showing a relationship between a set time and a pump displacement.

FIG. 17 is a diagram showing the relationship between the rotation speed of the prime mover and time.

FIG. 18 is a conceptual diagram showing a control system according to a third embodiment of the present invention.

FIG. 19 is a graph showing a relationship between a set maximum load line pressure and an oil temperature.

FIG. 20 is a diagram showing a relationship between a pump displacement and a pump displacement with respect to a difference between a pump pressure and a maximum load pressure.

FIG. 21 is a diagram showing a relationship between a water temperature and an air temperature and a set time.

FIG. 22 is a diagram showing a relationship between a set time and a set maximum load.

FIG. 23 is a conceptual diagram showing a control system when a prime mover is controlled by a controller in the third embodiment.

FIG. 24 is a conceptual diagram showing a control system according to a modified example of the second embodiment of the present invention.

25 is a conceptual diagram showing a control system when the oil temperature sensor according to the embodiment shown in FIG. 24 is not used.

FIG. 26 is a flowchart illustrating a warm-up mode according to the fourth embodiment.

FIG. 27 is a conceptual diagram showing a specific control system according to the third embodiment of the present invention.

FIG. 28 is a flowchart showing a warm-up mode in the embodiment shown in FIG. 27;

FIG. 29 is a diagram showing a relationship between a pump pressure and a bleed opening.

FIG. 30 is a diagram showing the relationship between the maximum value of the bleed valve opening and the water temperature.

FIG. 31 is a conceptual diagram showing a control system when an air temperature sensor is used in the first embodiment.

FIG. 32 is a graph showing a relationship between a set maximum load pressure and a water temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump 2 ... Motor 3 ... Pump displacement device 4 ... Relief valve 5 ... Bleed valve 6 ... Oil temperature sensor 7 ... Pressure sensor 8 ... Controller 9 ... Water temperature sensor 9a ... Timer 9b ... Air temperature sensor 10 ... Flow control valve 11 ... actuator 12 ... electromagnetic proportional valve 13 ... potentiometer 14 ... source pressure safety lever 15 ... pilot pump 16 ... flow control valve controller 17 ... auxiliary pilot pump 18 ... pressure reducing solenoid valve 19 ... shuttle valve 20 ... unloading valves 21a and 21b ... pressure reducing valve

Claims (9)

[Claims] 1. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump are set. A bleed valve for releasing pressure of a hydraulic pump circuit, oil temperature detecting means for detecting the temperature of hydraulic oil, and a value detected by the oil temperature detecting means. And a pump pressure setting means for setting a pressure of the hydraulic pump according to the hydraulic pressure of the hydraulic pump. 2. A prime mover, a variable displacement hydraulic pump driven by the prime mover, an actuator, a flow control valve for selectively supplying pressure oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump are set. A bleed valve for releasing pressure of a hydraulic pump circuit, oil temperature detecting means for detecting the temperature of hydraulic oil, and a value detected by the oil temperature detecting means. And a bleed valve opening setting means for setting a maximum opening of the bleed valve according to the following. 3. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump. Oil pressure for detecting the temperature of hydraulic oil in a hydraulic drive of a construction machine having a pump displacement device, a pump pressure detecting means for detecting a hydraulic pump circuit pressure, and a brute valve for releasing the pressure of the hydraulic pump circuit. Detecting means, pump pressure setting means for setting the pressure of the hydraulic pump in accordance with the value detected by the oil temperature detecting means, and pump pressure control for controlling the opening of the brute valve with the pump pressure setting means And a hydraulic drive device for a construction machine. 4. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying pressure oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump. Bleed valve for releasing the pressure of the hydraulic pump circuit, temperature detecting means for detecting any of water temperature of the motor, air temperature or hydraulic oil temperature, and starting of the motor A hydraulic drive device for a construction machine, comprising: a time measuring means for detecting a lapse of time later; and a time setting means for setting an opening time of a bleed valve according to a value detected by a temperature detecting means. 5. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic fluid from the hydraulic pump to the actuator, and a displacement of the hydraulic pump. Bleed valve for releasing the pressure of the hydraulic pump circuit, temperature detecting means for detecting any of water temperature of the motor, air temperature or hydraulic oil temperature, and starting of the motor Time measuring means for detecting the passage of time thereafter, time setting means for setting the opening time of the bleed valve according to the detected value of the temperature detecting means, and a value set by the time setting means or a value of the temperature detecting means Bleed valve opening setting means for setting the maximum value of the bleed valve opening according to the bleed valve determined by the time setting means and the time detected by the time measuring means Hydraulic drive system for a construction machine characterized by comprising Within the opening time value set in the bleed valve opening setting means and a bleed valve control means for controlling the maximum opening of the bleed valve. 6. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump are set. Oil pressure detecting means for detecting the temperature of hydraulic oil, lever operating amount detecting means for detecting an operating amount of an operating lever, and the oil temperature detecting means Control table selecting means for comparing the control table of the pump displacement device based on the respective detection values of the lever operating amount detecting means and the control table selecting means for selecting the larger one, and the pump based on the control table selected by the control table selecting means A hydraulic drive device for a construction machine, comprising: control means for controlling a displacement device. 7. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a lever for displacing the hydraulic pump. A hydraulic pressure detection device for a construction machine having a pump displacement device set in accordance with the operation amount of the engine, a temperature detection means for detecting any one of a motor water temperature, outside air, and hydraulic oil; and an operation amount of an operation lever. A comparison is made between the lever operation amount detection means for detecting the operation time, the timer means for measuring the elapsed time after the start of the prime mover, and the control table of the pump displacement device based on the detection values of the lever operation amount detection means and the temperature detection means. Control table selecting means for selecting the larger one, and a pump based on the control table selected by the control table selecting means. Hydraulic drive system for a construction machine of Shinoke volume unit, characterized in that it consists of a control means for controlling in a predetermined time corresponding to the detected value of the temperature detecting means. 8. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump. A pump displacement device that performs the control of the pump displacement device according to the difference between the pump pressure and the maximum load pressure of each actuator. Load pressure detecting means for detecting pressure, oil temperature detecting means for detecting hydraulic oil temperature, pressure generating means for generating a set maximum load line pressure corresponding to a value detected by the oil temperature detecting means, and pressure generating means The shuttle hand that guides the larger of the pressure generated by the above and the pressure detected by the load pressure detecting means to the maximum load pressure line of the actuator. Hydraulic drive system for a construction machine, characterized in that comprising a. 9. A motor, a variable displacement hydraulic pump driven by the motor, an actuator, a flow control valve for selectively supplying hydraulic oil from the hydraulic pump to the actuator, and a displacement of the hydraulic pump are set. A pump displacement device that performs the control of the pump displacement device according to the difference between the pump pressure and the maximum load pressure of each actuator. Load pressure detecting means for detecting the pressure, temperature detecting means for detecting either the prime mover water temperature, outside air or hydraulic oil temperature, timer means for measuring the elapsed time after the prime mover starts, and according to the detected value of the temperature detecting means. Time setting means for setting the time set, and a pressure corresponding to the set time set by the time setting means or the value of the temperature detecting means. Pressure setting means, pressure generation means for generating the pressure set by the pressure setting means if the time detected by the timer means is within the time set by the time setting means, And a shuttle means for guiding the larger pressure detected by the load pressure detecting means to the highest load pressure line of the actuator.