JPH0771411A - Working pressure selector device and selecting method for work machine - Google Patents

Abstract

PURPOSE:To shorten a high-pressure oil feeding time and extend the service life of a hydraulic system, regarding the hydraulic system of an actuator for turning motion. CONSTITUTION:The relief oil circuit of a hydraulic system is fitted with high- pressure and low-pressure relief valves 14 and 15 for setting relief pressure at low and high pressure sides, and a pressure oil selector valve 12 for changing over pressure oil feed to each relief valve. In addition, an inclination sensor 16 for detecting the inclination state of a machine body is connected to the selector valve 12, thereby opening the relief oil circuit running via the low- pressure relief valve 15 in gentle inclination state. Thus, a working pressure selector device and a working pressure selecting method for a work machine are constituted so that the relief oil circuit running via the high-pressure relief valve 14 is opened in steep inclination state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working pressure switching device and a switching method for a working machine constructed with a revolving structure such as a hydraulic shovel.

[0002]

BACKGROUND OF THE INVENTION Generally,
Among the working machines provided with this type of revolving structure, there is one in which the revolving structure is revolved by the operation of a revolving actuator (a revolving hydraulic motor) supplied with hydraulic pressure. However, in this structure, the revolving structure does not always rotate with a constant revolving torque, and when performing a revolving operation that resists the inertia of the revolving structure such as at the start of turning or when the revolving is stopped, or on the sloping ground work shown in FIG. In the case of turning toward the upper hand side of the inclination, the turning is performed in a state where a large turning torque is required. Further, the required turning torque in the case of slope work becomes larger as the inclination angle becomes larger.
Therefore, the pressure oil circuit for supplying the pressure oil to the turning actuator has to be designed in such a setting that the pressure oil corresponding to the maximum turning torque assumed in the work can be supplied. It was set to constantly supply high pressure oil corresponding to the maximum turning torque. For this reason, the hydraulic system must be adapted to this high pressure hydraulic oil, but the life of the hydraulic system is determined by the accumulation of the high pressure hydraulic oil supply time, which prolongs the service life. In order to measure, there is a problem that the hydraulic system must be expensive and large in size, which has high pressure resistance.

[0003]

SUMMARY OF THE INVENTION The present invention was devised with the object of providing an operating pressure switching device and a switching method in a working machine, which can eliminate these drawbacks in view of the above-mentioned circumstances. Then, in a working machine provided with a revolving body that receives pressure oil supply and revolves,
The pressure oil circuit for turning is provided with a plurality of relief valves having different relief pressures, and a pressure oil switching valve for switching the pressure oil supply to these relief valves. It is characterized in that it is connected to a load detecting tool for detecting, and the pressure oil switching valve is switched based on the size of the work load to supply the pressure oil to the corresponding relief valve. Further, the present invention relates to a working machine comprising a revolving structure which revolves upon receiving pressure oil supply, wherein each relief valve in which a relief pressure is set to a low pressure side or a high pressure side is provided in a pressure oil circuit for revolving. And a pressure oil switching valve that switches the pressure oil supply to each of these relief valves, and the pressure oil switching valve is connected to a machine body tilt sensor that detects the tilt state of the machine body to preset the machine body. It is characterized in that it is configured so that pressure oil is supplied to the low-pressure side and high-pressure side relief valves by switching based on the detection of a gentle inclination state or a steep inclination state with respect to the inclination angle. . Furthermore, the present invention provides a working machine comprising a revolving structure which revolves when receiving pressure oil supply, wherein a plurality of relief valves having different relief pressures are provided in a pressure oil circuit for revolving, and the relief valves are provided to these relief valves. The pressure oil switching valve provided to switch the pressure oil supply is switched based on the detection from the load detector that detects the work load status, and the pressure oil is supplied to the relief valve corresponding to the load. It is a feature. Furthermore, the present invention relates to a working machine comprising a revolving structure that revolves when receiving pressure oil supply, wherein relief pressures for the revolving pressure oil circuit are set to a low pressure side and a high pressure side, respectively. Is provided, the pressure oil switching valve provided to switch the pressure oil supply to these relief valves is switched, and the airframe is gently inclined with respect to a preset inclination angle from the airframe inclination sensor that detects the airframe inclination state, It is characterized in that pressure oil is supplied to the relief valves on the low-pressure side and the high-pressure side according to the detection of the steeply tilted state, corresponding to the tilted state of the machine body.

According to the present invention, the pressure oil is supplied according to the work load so that the life of the hydraulic system can be extended.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a hydraulic shovel, and the hydraulic shovel 1 is a crawler type traveling body 2 and the traveling body 2
Of the engine (not shown) mounted on the revolving structure 3. The revolving structure 3 is rotatably supported above the revolving structure 3, the working unit 4 connected to the front part of the revolving structure 3, and the like. Although it is hydraulically operated by power, all of these basic configurations are conventional.

The turning of the turning body 3 is performed based on the operation of the turning actuator 5 which receives the hydraulic pressure.
The present invention is embodied in a pressure oil system for supplying a hydraulic pressure to the turning actuator 5. That is, the turning actuator 5 has the main valve 6 as described later.
The oil passage from the main pump 7 to the left side of the actuator or the right side of the actuator is opened and closed based on the switching operation of the main valve 6, whereby the left and right turning operation is performed. A six-port three-position switching valve, the switching operation of which is supplied based on the alternative valve path opening / closing operation of the left operation switching valve 9 or the right operation switching valve 9a based on the operation of the operation lever 8. It is supposed to be done by pressure oil. In the main valve 6, when the pilot pressure oil is not supplied, the valve passages from the main pump 7 to the actuator left turning side and the right turning side are closed, and the main pump 7 opens the main relief valve 10. Through the oil tank 11
It is in the neutral position where the valve leading to is opened. On the other hand, when the pilot pressure oil is supplied to the left turn side pilot chamber 6a, the valve path from the main pump 7 to the actuator left turn side, and the oil tank 11 from the actuator right turn side.
To the left turning side position in which the valve paths from the main pump 7 to the oil tank 11 via the main relief valve 10 are closed, and the pilot pressure oil is When it is supplied to the right turning side pilot chamber 6b, the valve path from the main pump 7 to the actuator right turning side and the valve path from the actuator left turning side to the oil tank 11 are both opened, and from the main pump 7 The valve path from the main relief valve 10 to the oil tank 11 is set to switch to the closed rightward turning position.

Further, reference numeral 12 is a pressure oil switching valve, which is provided in a relief oil passage branched from an intermediate portion of the oil passage extending from the main pump 7 to the main valve 6. The pressure oil switching valve 12 is an electromagnetic three-port three-position value switching valve, and switches to a neutral position, a high pressure side position, and a low pressure side position based on a command from a control unit 13 described later. There is. And pressure oil switching valve 12
In the state of being in the neutral position, the port on the inlet side is in a closed state, and the pressure oil does not flow into the relief oil passage. On the other hand, when it is in the high pressure side position, the valve path from the main pump 7 to the hydraulic tank 11 via the high pressure relief valve 14 is opened, and when it is in the low pressure side position, The valve passage leading to the hydraulic tank 11 via the low pressure relief valve 15 is set to open. Here, the high pressure relief valve 14 has a relief pressure set to a predetermined high pressure value, and the low pressure relief valve 15 has a relief pressure set to a predetermined low pressure value. When the valve 12 is in the high pressure side position and the relief oil passage via the high pressure relief valve 14 is opened, the pressure oil supply pressure to the turning actuator 5 becomes high, and the pressure oil switching valve When 12 is in the low pressure side position and the relief oil passage passing through the low pressure relief valve 15 is opened, the supply pressure of the pressure oil to the turning actuator 5 is low.

On the other hand, reference numeral 16 is an inclination sensor for detecting the inclination angle of the machine body. The inclination sensor 16 is mounted at an appropriate position on the front portion of the revolving structure 3, and the detected value is the control unit 1.
3 is input. Then, in the control unit 13, the detected value θ of the airframe inclination angle input from the inclination sensor 16 is in a gentle inclination state (θ ≦ α) or a steep inclination state (θ> α) with respect to a preset angle α. If it is determined that the vehicle is steeply inclined, a switching command is output to the pressure oil switching valve 12 so that the pressure oil switching valve 12 is set to the high pressure side position.
When it is determined that the vehicle is in the gently sloping state, it is set to output a switching command so as to be in the low pressure side position.

The high pressure and low pressure relief valves 14 and 15 are used.
When setting the relief pressure of and the setting angle α,
In the state where the pressure oil switching valve 12 is located at the high pressure side position and the relief oil passage passing through the high pressure relief valve 14 is opened, the pressure supply corresponding to the assumed maximum swing torque is generated by the swing actuator 5. Was made against
In the state where the pressure oil switching valve 12 is in the low pressure side position and the relief oil passage that passes through the low pressure relief valve 15 is open, the maximum turning torque when the vehicle turns in the inclined state of the set angle α or less is obtained. It is set to provide a corresponding pressure supply.

In the embodiment of the present invention constructed as described above, the revolving structure 3 is revolved by the operation of the revolving actuator 5 which is supplied with pressure oil based on the switching operation of the main valve 6. However, in supplying pressure oil to the turning actuator 5, if the vehicle is in a steep inclination and a large turning torque is required, the control unit 13 moves to the high pressure side position with respect to the pressure oil switching valve 12. The switching command is output to open the relief oil passage passing through the high pressure relief valve 14 and the high pressure oil is supplied to the turning actuator 5.

On the other hand, when the machine body is in a gentle inclination and a large turning torque is not required, the control unit 13 outputs a switching command to the pressure oil switching valve 12 so that the pressure oil switching valve 12 is in the low pressure side position. Then, a relief oil passage passing through the low pressure relief valve 15 is formed, and low pressure oil is supplied to the turning actuator 5.

As described above, in the embodiment of the present invention,
The pressure oil is supplied to the turning actuator 5 when the vehicle is in a steep inclination state and a large turning torque is required.
When high pressure oil is supplied corresponding to this, and the aircraft is in a gentle inclination state and does not require a large turning torque,
Corresponding to this, the low pressure oil is supplied.
As a result, unlike the conventional case, high pressure oil corresponding to the maximum turning torque is not always supplied, and hydraulic operation at low pressure that is hardly related to the life of the hydraulic system is automatically performed when necessary. Therefore, the cumulative value of the high-pressure pressure oil supply time, which is deeply related to the life of the hydraulic system, can be surely reduced, so that the pressure oil system can be made particularly high in cost, large in size, and large in size. Longevity can be achieved without using the above.

Of course, the present invention is not limited to the above-mentioned embodiment, and the load detecting tool for detecting the work load condition is not limited to the tilt sensor, but various work load detecting sensors and the like. Can be appropriately adopted as necessary.

[0014]

In summary, since the present invention is constructed as described above, a relief valve having a relief pressure corresponding to the work load detected by the load detector is provided. As the pressure oil switching valve switches so that pressure oil is supplied, the turning actuator has
Pressure oil having a pressure corresponding to the magnitude of the work load is supplied. As a result, unlike the conventional case, high pressure oil corresponding to the maximum turning torque is not always supplied, and hydraulic operation at low pressure that is hardly related to the life of the hydraulic system is automatically performed when necessary. Therefore, the cumulative value of the high-pressure pressure oil supply time, which is deeply related to the life of the hydraulic system, can be surely reduced. Even without it, the life of the pressure oil system can be extended.

[Brief description of drawings]

FIG. 1 is a perspective view of a hydraulic shovel during work on a slope.

FIG. 2 is a hydraulic circuit diagram of a swing actuator.

FIG. 3 is a hydraulic circuit diagram of a swing actuator showing a conventional example.

[Explanation of symbols]

 3 Revolving structure 5 Actuator for revolving 12 Pressure oil switching valve 14 High pressure relief valve 15 Low pressure relief valve 16 Tilt sensor

Claims (6)

[Claims] 1. A working machine comprising a revolving structure that revolves when supplied with pressure oil, wherein a plurality of relief valves having different relief pressures are provided in a pressure oil circuit for revolving and pressures to these relief valves. A pressure oil switching valve for switching the oil supply is provided, and the pressure oil switching valve is connected to a load detection tool for detecting the work load status to switch the pressure oil switching valve based on the magnitude of the work load. A working pressure switching device in a working machine, characterized in that pressure oil is supplied to a corresponding relief valve. 2. The working pressure switching device in a work machine according to claim 1, wherein the load detection tool for detecting the work load condition is a machine body tilt sensor. 3. A working machine comprising a revolving structure that revolves when receiving pressure oil supply, and a relief oil valve for revolving, wherein relief pressures are set to a low pressure side and a high pressure side, respectively. , A pressure oil switching valve for switching the pressure oil supply to each of these relief valves is provided, and the pressure oil switching valve is connected to a machine body inclination sensor for detecting the tilt state of the machine body, so that the machine body is set in advance. An operation in a working machine characterized in that it is configured to supply pressure oil to the low-pressure side and high-pressure side relief valves by switching based on detection of a gentle inclination state or a steep inclination state with respect to an angle. Pressure switching device. 4. A working machine comprising a revolving structure that revolves when supplied with pressure oil, wherein a plurality of relief valves having different relief pressures are provided in a pressure oil circuit for revolving, and pressures to these relief valves are provided. The pressure oil switching valve provided to switch the oil supply is switched based on the detection from the load detector that detects the work load status, and the pressure oil is supplied to the relief valve corresponding to the load. And method for switching working pressure in working machines. 5. The operating pressure switching method for a work machine according to claim 4, wherein the load detection tool for detecting the work load status is a machine body tilt sensor. 6. A working machine comprising a revolving structure which revolves upon receiving a supply of pressure oil, wherein the pressure oil circuit for revolving is provided with respective relief valves whose relief pressure is set to a low pressure side and a high pressure side. , The pressure oil switching valve provided to switch the pressure oil supply to these relief valves is switched from a tilt sensor that detects the tilting state of the machine body to a gentle inclination state or a steep inclination with respect to a preset inclination angle. A working pressure switching method in a working machine, characterized in that pressure oil is supplied to the low-pressure side and high-pressure side relief valves in response to the state of inclination of the machine body, based on detection of the state.