KR101276982B1 - Hydraulic System for Controlling Travel-Combined Motions of an Excavator - Google Patents

Abstract

The present invention drives the plurality of hydraulic pumps with the output of one engine, and the traveling speed is not reduced during the combined driving operation by simultaneously operating the traveling motor and the actuator for the front work device with the pressure oil discharged from the plurality of hydraulic pumps. It relates to a hydraulic system for controlling.

The present invention includes a driving whether detecting means for detecting whether the excavator is running, and a relief valve installed on the hydraulic supply line of the hydraulic pump for the front work device, wherein the relief valve is running whether the running detection means of the excavator If it is detected, characterized in that the variable relief valve for reducing the relief pressure of the hydraulic pump for the front work device.

Excavator, Variable Relief Valve, Combined Travel Motion, Travel Speed

Description

Hydraulic System for Controlling Travel-Combined Motions of an Excavator

1 is a schematic hydraulic circuit diagram of a hydraulic system for controlling a traveling combined motion of a conventional excavator;

2 is a pressure-flow diagram of a variable displacement hydraulic pump providing pressure oil to a traveling motor in a hydraulic system of a conventional excavator;

3 is a relief pressure diagram of the relief valve of the hydraulic pump for the front work device in the hydraulic system of the conventional excavator,

4 is a schematic hydraulic circuit diagram of a first embodiment of a hydraulic system for controlling a traveling combined motion of an excavator according to the present invention;

5 is a relief pressure diagram of the embodiment of FIG.

FIG. 6 is a pressure-flow diagram of the hydraulic pump for driving of the embodiment of FIG. 4;

Figure 7 is a schematic hydraulic circuit diagram of a second embodiment of the hydraulic system for controlling the combined traveling motion of an excavator according to the present invention.

Figure 8 is a schematic hydraulic circuit diagram of a third embodiment of the hydraulic system for controlling the traveling combined motion of an excavator according to the present invention.

※ Explanation of code about main part of drawing ※

10: engine 11: first hydraulic pump

12: 2nd hydraulic pump 11A, 12A: flow control mechanism

13: 3rd hydraulic pump 20: control valve

21: left driving control spool 21A, 21B: hydraulic part

22: left traveling hydraulic motor 23: space control spool

23A, 23B: Hydraulic section 24: Space travel hydraulic motor

25: boom control spool 26: arm control spool

27: boom cylinder 28: dark cylinder

30: Hydraulic supply line 31: Front supply control valve

T: tank 32: discharge line

33: variable relief valve 33A: hydraulic

Ptl1, Ptl2, Ptr1, Ptr2: Travel Pilot Pressure 34: Travel Signal Pressure Detection Line

35: driving signal sensor 36: solenoid valve

37: solenoid part

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system for controlling a traveling complex operation of an excavator, and in particular, to drive a plurality of hydraulic pumps with the output of one engine, and the hydraulic motor discharged from the plurality of hydraulic pumps, the actuator for the driving motor and the front work device. It relates to a hydraulic system for controlling so that the running speed is not reduced during the combined travel operation by operating the simultaneous operation.

A small excavator used for a relatively light load of an excavator generally includes three hydraulic pumps, and is driven by connecting these three hydraulic pumps to one engine. The hydraulic system of such a small excavator distributes the hydraulic oil discharged from each of the three hydraulic pumps to the driving motor and the actuators for the front work device to perform the driving or the front work alone, or the combined travel operation in which the driving and the front work are performed simultaneously. Will be performed.

As shown in FIG. 1, the hydraulic system of the conventional compact excavator as described above includes the engine 101 and the variable displacement first hydraulic pump 102 driven by the output of the engine 101. A plurality of hydraulic pumps (103, 103, 104) and a plurality of hydraulic actuators (105, 106, 107, 108) are distributed to the plurality of hydraulic actuators (105, 106, 107, 108) to distribute the hydraulic oil discharged from the three hydraulic pumps (102, 103, 104). And a control valve 110 having two control spools 111, 112, 113, 114, and 120.

The first hydraulic pump 102 and the second hydraulic pump 103 are the left driving hydraulic motor 105 and the space through the left running control spool 111 and the space running control spool 112 of the control valve 110, respectively. The hydraulic pressure is supplied to the row hydraulic motor 106, and the third hydraulic pump 104 passes through the front supply control valve 120, and the hydraulic actuators 107 and 108 for the front work device such as boom cylinders, arm cylinders, bucket cylinders, dozer cylinders, and the like. And selectively provide pressure oil to these hydraulic actuators 107 and 108 according to the type of work.

In addition, a relief valve 123 is provided in the hydraulic line 121 for supplying the discharge pressure oil of the third hydraulic pump 104 to the hydraulic actuators 107 and 108 for the front work device to discharge the third hydraulic pump 104. The pressure is limited so as not to exceed a predetermined pressure.

As described above, in the conventional hydraulic system of a small excavator, the three hydraulic pumps 102, 103, and 104 are driven together at the output of one engine 101, and thus, the first hydraulic pump 102 is supplied to the traveling hydraulic motors 105 and 106. ) And the discharge flow rate of the second hydraulic pump 103 is varied according to the discharge pressure of the third hydraulic pump 104.

However, as shown in FIG. 3, the relief valve 123 maintains a constant relief pressure at all times when driving or not driving, and as shown in the graph of FIG. The discharge flow rates of the hydraulic pump 102 and the second hydraulic pump 103 are between the case where the third hydraulic pump 104 is in the no-load state P3_idle and when the third hydraulic pump 104 is in the relief state P3_relief. Fluctuates.

As a result, when the discharge pressure of the third hydraulic pump 104 does not reach the relief condition because the front work load is not so large while only driving or driving-front combined operation, as shown by the solid line graph Y of FIG. 2. The discharge flow rates of the first hydraulic pump 102 and the second hydraulic pump 103 do not decrease, so that the running speed does not decrease.

However, when the discharge pressure of the third hydraulic pump 104 rises to the maximum and is in the relief condition (P3_relief), for example, driving with a weight on the bucket, driving while pushing soil with a doser, or moving the arm on an inclined surface at a steep slope. As shown in the dotted line graph (X) of FIG. 2 when the driving compound operation is performed in a state in which the load of the front work is large, such as when the vehicle is pulled in the fixed state and the vehicle is towed along the slope. Similarly, since the discharge flow rates of the first hydraulic pump 102 and the second hydraulic pump 103 are drastically reduced and the flow rate supplied to the traveling hydraulic pumps 105 and 106 is drastically reduced, the traveling complex which simultaneously performs traveling and front work. In the case of operation, the running speed is significantly lowered, which causes a problem of poor performance of the driving compound operation.

Accordingly, an object of the present invention is to solve the shortcomings of the conventional compact excavator, and to provide a hydraulic system for controlling a combined driving motion that can improve the combined driving performance by eliminating the traveling speed reduction phenomenon in the combined driving operation.

The present invention for achieving the above object, the traveling hydraulic pump for supplying the hydraulic oil to the traveling motor for traveling of the excavator, and the traveling control spool for controlling the flow rate of the hydraulic oil supplied from the traveling hydraulic pump to the traveling motor; And a hydraulic system for controlling a traveling compound operation of an excavator equipped with a hydraulic pump for a front working device for supplying pressure oil to a hydraulic cylinder for driving the front working device of the excavator, the traveling system detecting means for detecting whether the excavator is traveling; And a relief valve installed on a hydraulic supply line of the hydraulic pump for the front work device, wherein the relief valve is a relief pressure of the hydraulic pump for the front work device when the traveling state detecting means detects the traveling of the excavator. The variable relief valve for reducing the, The running whether detection means, the driving signal detection sensor for outputting an electric signal by detecting the driving signal output when the driver operating the driving operation means, The variable relief valve, It is preferable to include a solenoid portion for adjusting the magnitude of the relief pressure receives an electrical signal from the driving signal sensor.

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In addition, in the present invention, the hydraulic pump for driving supplies pressure oil to at least one of the driving motor and the front work device, when the driving and front work at the same time to supply the pressure oil to the traveling motor preferentially It is desirable to.

And in the present invention, it is preferable that the hydraulic pump for the front work device is a fixed displacement pump, the traveling hydraulic pump is a variable displacement pump.

According to the present invention as described above, the front operation of supplying the pressure oil to the front operation apparatus of the plurality of hydraulic pumps driven by one engine in the case of the combined travel operation of performing the front operation with high workload and the traveling operation at the same time By lowering the discharge flow rate of the hydraulic pump for the device, it is possible to increase the discharge speed by relatively increasing the discharge flow rate of the remaining driving hydraulic pump for driving the driving motor, thereby improving the performance of the driving compound operation during the driving compound operation.

Hereinafter, an embodiment of a hydraulic system for controlling a traveling composite motion of an excavator according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic hydraulic circuit diagram showing a first embodiment of a hydraulic system for controlling combined travel operation according to the present invention. In FIG. 4, only the boom cylinder and the female cylinder are illustrated among the plurality of front working devices and the hydraulic cylinders for controlling the front working device, and the remaining hydraulic cylinders and the control spool for controlling the hydraulic cylinders are omitted.

As shown in FIG. 4, one engine 10 and three hydraulic pumps 11, 12, 13 driven by the engine 10 are provided. Of the three hydraulic pumps 11, 12 and 13, two hydraulic pumps, that is, the first hydraulic pump 11 and the second hydraulic pump 12, are driving hydraulic pumps for driving the driving motors 22 and 24. A variable displacement hydraulic pump whose discharge flow rate is varied by the respective flow control mechanisms 11A and 12A. The other hydraulic pump, that is, the third hydraulic pump 13, is a hydraulic pump for the front work device for driving the front work device, and is a fixed capacity hydraulic pump.

The first hydraulic pump 11 is connected to the left running hydraulic motor 22 via the left running control spool 21 of the control valve 20, and the second hydraulic pump 12 is the space of the control valve 20. It is connected to the space travel hydraulic motor 24 via the row control spool 23. That is, the first hydraulic pump 11 and the second hydraulic pump 12 provide hydraulic power to the left driving motor 22 and the space running motor 24, respectively, to provide driving power of the excavator.

The third hydraulic pump 13 is connected to the boom cylinder 27 and the dark cylinder 28 through the boom control spool 25 and the arm control spool 26, respectively. In addition, a front supply control valve 31 is provided on the hydraulic supply line 30 that provides the hydraulic oil of the third hydraulic pump 13 to the boom control spool 25 and the arm control spool 26, so that the third hydraulic pump 13 is provided. ) Is supplied or shut off to the boom control spool 25 or the arm control spool 26.

In addition, a discharge line 32 connected to the tank T is branched to an upstream hydraulic supply line 30 of the front supply control valve 31, and a third hydraulic pump 13 is connected to the discharge line 32. A relief valve 33 is provided to relief the discharge pressure of the gas not to exceed a predetermined pressure.

The relief valve 33 is composed of a variable relief valve capable of varying the relief pressure, the pressure receiving portion 33A provided on one side is connected to the running status detection means. In the present embodiment, the driving state detecting means may set any one of the driving pilot pressures Ptl1, Ptl2, Ptr1, and Ptr2 acting on the pressure receiving units 21A, 21B (23A, 23B) of the driving control spools 21, 23. The driving signal pressure detection line 34 is detected and provided to the hydraulic pressure unit 33A of the variable relief valve 33.

Therefore, when the driving operation is performed by the driving operation means (not shown), the traveling pilot pressure of the pilot pump (not shown) is supplied to one side hydraulic pressure unit 21A, 21B, 23A, of the driving control spools 21, 23 through the traveling pilot line. 23B), the driving control spools 21 and 23 are switched to the traveling position, so that the hydraulic oil of the first hydraulic pump 11 and the second hydraulic pump 12 passes through the driving control spools 21 and 23. Is provided to the traveling hydraulic motors 22 and 24 to perform the traveling operation.

At this time, the traveling pilot pressure of the traveling pilot line is detected through the traveling signal pressure detection line 34 and the hydraulic part of the variable relief valve 33 provided in the hydraulic supply line 30 of the third hydraulic pump 13. By acting on 33A, the relief pressure of the variable relief valve 33 is lowered from " A " to " B "

As a result, as shown in Fig. 6, the pressure-flow curves of the first hydraulic pump 11 and the second hydraulic pump 12 are converted to the curve " Y " Will move. According to the change in the 'pressure-flow curve' of the first hydraulic pump 11 and the second hydraulic pump 12, the discharge signal of the first hydraulic pump 11 and the second hydraulic pump 12 is detected by a running signal. It is relatively larger than the case of the graph " X " That is, the discharge flow rate of the first hydraulic pump 11 and the second hydraulic pump 12, which provides the driving power during the combined operation of the traveling and front work, can be relatively increased to prevent the traveling speed from decreasing. Operation performance can be improved.

7 shows a schematic hydraulic circuit diagram of a second embodiment of a traveling complex of an excavator according to the invention. The second embodiment of the present invention shown in FIG. 7 is different from the first embodiment of the present invention shown in FIG. Only the driving condition detecting means having a different configuration will be described in detail.

In the second embodiment of the present invention shown in FIG. 7, the travel detection means acts on the hydraulic pressure units 21A, 21B, 23A, 23B of the travel control spools 21, 23 of the control valve 20. Travel signal pressure detection line 34 which detects the traveling pilot pressure and transmits it to the hydraulic unit 33A of the variable relief valve 33, and travels by sensing the travel signal from the driving operation means (not shown) and outputting an electrical signal. It is characterized in that it consists of a signal sensor 35 and the solenoid valve 36 for opening and closing the driving signal pressure detection line 34 in accordance with the presence or absence of an electrical signal provided by the driving signal sensor 35.

According to the second embodiment of the present invention configured as described above, when the driving signal is operated by outputting the driving signal, the driving pilot pressure of the pilot pump (not shown) is driven through the driving pilot line. The driving control spools 21 and 23 are switched to the traveling position by acting on one side hydraulic pressure unit of the driving unit, so that the hydraulic pressure of the first hydraulic pump 11 and the second hydraulic pump 12 is changed to the driving control spools 21 and 23. It is provided to the traveling hydraulic motors 22 and 24 through the driving.

At this time, the travel signal sensor 35 detects the travel signal of the travel operation means and applies it to the solenoid portion 36A of the solenoid valve 36 to switch the solenoid valve 36 to the open position. Accordingly, the driving signal pressure detection line 34 is opened to provide the driving pilot pressure to the hydraulic pressure unit 33A of the variable relief valve 33. Accordingly, the variable relief valve 33 provides the relief pressure shown in FIG. Lower it from "A" to "B".

8 shows a schematic hydraulic circuit diagram of a third embodiment of the present invention. Since the configuration of the third embodiment of the present invention shown in FIG. 8 is different from the second embodiment of the present invention shown in FIG. 7 only in the driving condition detecting means, the driving condition detecting means will also be described in detail. Shall be.

In the third embodiment of the present invention shown in FIG. 8, the driving condition detecting means includes a driving signal detecting sensor 35 which detects the driving signal from the driving operation means (not shown) and outputs an electrical signal. The relief valve 33 is characterized by having a solenoid portion 37 for directly changing the relief pressure of the variable relief valve 33 in accordance with the presence or absence of an electrical signal provided by the travel signal sensor 35.

According to the third embodiment of the present invention configured as described above, when the driving signal is operated by outputting the driving signal, the driving pilot pressure of the pilot pump (not shown) is driven through the driving pilot line. The driving control spools 21 and 23 are switched to the traveling position by acting on one side hydraulic pressure unit of the driving unit, so that the hydraulic pressure of the first hydraulic pump 11 and the second hydraulic pump 12 is changed to the driving control spools 21 and 23. It is provided to the traveling hydraulic motors 22 and 24 through the driving.

At this time, the driving signal detecting sensor 35 detects the driving signal of the driving operation means and applies an electrical signal to the solenoid part 37. The variable relief valve 33 is operated by the operation of the solenoid part 37. Is lowered from "A" to "B" shown in FIG.

In the second and third embodiments of the present invention, as in the first embodiment, the first hydraulic pump 11 and the second hydraulic pump are lowered by lowering the relief pressure of the third hydraulic pump 13 according to the driving signal during driving. By relatively increasing the discharge flow rate of (12), it is possible to prevent the reduction of the traveling speed in the case of a traveling compound operation in which both driving and front work are performed at the same time, thereby improving the performance of the driving compound operation.

Meanwhile, in each embodiment of the present invention, the first hydraulic pump 11 and the second hydraulic pump 12 which are traveling hydraulic pumps not only supply the hydraulic oil to the traveling motors 22 and 24 but also drive the front work device. It is preferable to supply also to the boom cylinder 27 and the dark cylinder 28 which are hydraulic cylinders. This is particularly useful when it is necessary to compensate for the excessive reduction in the pressure of the hydraulic oil supplied to the hydraulic cylinders 27 and 28 for the front work device by the variable relief valve 33. However, it is supplementary to supply the hydraulic oil to the hydraulic cylinder for the front work equipment because the driving speed should be prevented from decreasing, and the priority of the hydraulic oil supply should be the driving motor.

The hydraulic system for controlling the traveling combined motion of an excavator according to the present invention includes a travel relief means and a variable relief valve interlocked therewith, so that the relief pressure of the hydraulic pump for the front work device can be adjusted when the excavator travels. In the case of a compound driving operation which simultaneously performs a high load front operation and a driving operation, the discharge flow rate of the hydraulic pump supplying the hydraulic motor to the driving motor is relatively increased, thereby preventing the driving speed from being reduced during the driving compound operation. It can improve operation performance.

In addition, when the traveling status detecting means is provided with a solenoid valve, it is possible to provide a uniform driving pilot pressure to the hydraulic pressure portion of the variable relief valve, and to control the variable relief valve electronically, thereby improving accuracy.

Furthermore, when the variable relief valve is provided with a solenoid portion, the configuration of the hydraulic circuit is simplified since the solenoid portion can directly adjust the relief pressure.

Claims (6)

A traveling hydraulic pump for supplying hydraulic oil to the traveling motor for traveling of the excavator, a traveling control spool for controlling the flow rate of the hydraulic oil supplied from the traveling hydraulic pump to the traveling motor, and driving the front work device of the excavator. In the hydraulic system for controlling the traveling motion of an excavator equipped with a hydraulic pump for the front work device for supplying the hydraulic oil to the hydraulic cylinder, Running status detecting means for detecting driving status of the excavator; And And a relief valve installed on a hydraulic supply line of the hydraulic pump for the front work device, wherein the relief valve is configured to adjust the relief pressure of the hydraulic pump for the front work device when the traveling state detecting means detects the traveling of the excavator. Variable relief valve to reduce, The driving whether detecting means includes a driving signal detecting sensor for detecting the driving signal output when the driver operates the driving operation means and outputs the electrical signal, The variable relief valve, the hydraulic system for controlling the combined movement of the excavator, characterized in that it comprises a solenoid unit for receiving the electrical signal from the traveling signal detection sensor to adjust the magnitude of the relief pressure. delete delete delete The method of claim 1, The traveling hydraulic pump supplies pressure oil to at least one of the driving motor and the front work device, and when the driving and front work are performed at the same time, the hydraulic pressure is preferentially supplied to the driving motor. System for the control of combined travel of the car. 6. The method according to claim 1 or 5, The hydraulic pump for the front work device is a fixed displacement pump, the traveling hydraulic pump is a hydraulic system for controlling the combined operation of the excavator, characterized in that the variable displacement pump.

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