KR20030004695A - Hydraulic control apparatus for excavator in idling - Google Patents

Abstract

PURPOSE: A hydraulic control device of an excavator is provided to lower the discharge of main pumps to a minimum and to reduce the rotational frequency of an engine to a minimum. CONSTITUTION: The hydraulic control device of an excavator comprises at least one or more main pumps(1,2), a main control valve(3) controlling the flow of pressure oil from each main pump(1,2) to many working units, orifices(9c,10c) installed on passages(9a,10a) diverged from center bypass lines(4,5) passing through the main control valve(3) and connected to a drain tank, NEGA cone lines(4a,5a) connected from the center bypass lines(4,5) to a pump regulator(6,7) of the main pumps(1,2), a no-load driving sensor sensing the no-load driving state of an excavator, a controller(8) controlling the rotational frequency of an engine to a minimum by the no-load driving signals sensed by the no-load driving sensor, roundabout passages(9d,10d) detouring the orifices(9c,10c), then connecting the lower part of the center bypass lines(4,5) with the drain tank, switch valves(9,10) intercepting or connecting the roundabout passages(9d,10d), and a switching instrument switching the switch valves(9,10) by getting switch signals from the controller(8) when the no-load signals are detected from the no-load driving sensor.

Description

Hydraulic control apparatus for excavator in idling}

The present invention relates to a hydraulic control device of an excavator, and more particularly to a hydraulic control device that can improve the fuel economy by reducing unnecessary fuel waste by reducing the load on the engine for driving the pump when the excavator is not working.

Conventional excavators generally use variable displacement hydraulic pumps as the main pumps 51 and 52, and increase or decrease the negative pressure depending on the flow rate of the main pumps 51 and 52 passing through the center bypass line of the main control valve. Therefore, it adopts "Negative Control System" (hereinafter simply abbreviated as "Negacon" control method) to control the discharge flow rate of the variable displacement hydraulic pump, and also the number of revolutions of the engine driving the main hydraulic pump The main hydraulic pump is adjusted in response to the change in the discharge flow rate.

That is, the hydraulic control device of the conventional excavator as described above, as shown in Figure 1, when the front work devices such as boom, arm, etc., the corresponding control spools 53a, 53b of the main control valve 53 is a remote control valve Since the pilot signal pressure (not shown) is switched from the neutral position to the operating position, the oil pressure does not flow through the center bypass lines 54 and 55 so that the pressure of the negative cone valves 56 and 57 is lowered. The lowered negative cone pressure acts on the pump regulators 58 and 59 through the negative cone lines 54a and 55a to increase the discharge flow rates of the main pumps 51 and 52.

At the same time, the front job detection signal line Px connected to the drain line R through the front job device control spools 53a of the main control valve 3 in sequence is switched by the front job device control spool 53a. When the front work signal line Px is cut off or when the travel control spool 53b is switched, the travel signal line communicating with the drain line R through the auxiliary pump 60 in turn passes through the left and right travel control spool 53b. Py) will be blocked. In this case, a signal pressure is formed in each signal line Px and Py, and is sensed by the pressure switches 61a and 61b provided on the respective signal lines Px and Py. It transmits a signal about driving. The controller 62 which detects the operation or driving state of the front work device controls the engine governor 63 driving the main pumps 51 and 52 so that the main pumps 51 and 52 correspond to the workload. The engine speed is increased to discharge the gas.

On the contrary, when the front work device does not operate and does not travel, the corresponding control spool of the main control valve 53 is positioned in the neutral position, and the pressure oil discharged from the main pumps 51 and 52 is negative cone valves 56 and 57. Drain through the drain line to the tank, where the negative cone pressure detected by the negative cone valves 56 and 57 is increased, and the discharge flow rates of the main pumps 51 and 52 through the pump regulators 58 and 59 are increased. To the minimum. At the same time, the pressure oil of the auxiliary pump 60 passing through the front work detection signal line Px and the driving detection signal line Py is drained into the tank through the drain line R as it is, and these signal lines Px and Py No pressure is formed in the air, and the pressure switches 61a and 61b apply a signal to the controller 60 to lower the engine speed corresponding to the minimum discharge flow rate of the main pump, thereby reducing the fuel consumption required for driving the engine. It is supposed to reduce.

However, in the conventional hydraulic control device of the excavator, the negative cone valves 56 and 57 have flow rates of the main pumps 51 and 52 passing through the center bypass lines 54 and 55 as shown in FIG. 1. The orifice 56a, 57a is provided on the flow path drained to R), and the pressure generated when the flow rate passes through the orifice is detected as the negative cone pressure, so that the orifice is not operated even when the operation is not performed. Due to the pressure generated when passing, the negative pressure is formed to a certain value (typically 40 bar) higher than the back pressure of the tank. Because of the negative cone pressure, the engine is operated under a constant load even in the idling state without front work or driving, and thus, the engine consumes more fuel than when the engine is operated under full no load.

In addition, since the negative-cone valves 56 and 57 have a structure as shown in FIG. 2, when the hydraulic oil of the main pumps 51 and 52 passes through the orifices 56a and 57a or the lower ends of the spools 56b and 57b, An abnormal sound is generated when the hydraulic oil passes through the gap between the valve seat and the valve seat.

Therefore, the present invention is designed to solve the disadvantages of the conventional hydraulic control device of the excavator, during the operation of the equipment to discharge a sufficient flow rate of the pump and correspondingly increase the engine output dog, while at the idle idling By bypassing the discharge flow rate of the pump to the tank to lower the pump pressure to the equipment back pressure level, while also correspondingly lowering the engine output to provide a hydraulic control device that can improve fuel efficiency by reducing unnecessary fuel consumption. There is a purpose.

It is another object of the present invention to provide a low noise hydraulic control device by reducing the noise generated in the negative cone valve.

1 is a hydraulic circuit diagram of a conventional excavator hydraulic control apparatus,

Figure 2 is a cross-sectional view showing the structure of the negative cone valve of the conventional excavator hydraulic control device,

3 is a schematic hydraulic circuit diagram of an excavator hydraulic control apparatus according to the present invention;

Figure 4 is a hydraulic circuit diagram of another embodiment of the excavator hydraulic control apparatus of the present invention.

※ Explanation of code about main part of drawing ※

1,2: main hydraulic pump 3: main control valve

3a ~ 3g: Front work device control spool 3h, 3i: Travel control spool

4,5: Center bypass line 4a, 5a: negative cone line

6,7: Pump regulator 8: Controller

9,10: switching valve 9a, 10a: flow path

9c, 10c: orifice

9d, 10d: bypass euro 11: auxiliary pump

Px: Front job detection signal line Py: Travel detection signal line

14: pressure switch 15: shuttle valve

16: negative switching signal line 17: solenoid valve

18a, 18b: Shuttle valve 19: Engine governor

E: engine

The present invention for achieving the above object is at least one main pump, a main control valve for controlling the flow of pressure oil discharged from each of the main pump toward a plurality of working machines, and a center-by-through through the main control valve An orifice installed on a flow path branched from a pass line and connected to a drain tank, a negative cone line connected to the pump regulator of the main pump at the center bypass line, and a no-load operation detecting means for detecting a no-load operation state of the excavator; In the hydraulic control device of an excavator including a controller for adjusting the engine speed to the minimum by the no-load operation signal detected by the no-load operation detection means,

A bypass flow path that bypasses the orifice and connects the downstream side of the center bypass line and a drain tank, a switching valve that blocks or communicates the bypass flow path, and when no load is detected from the no-load operation detecting means. It is characterized in that it further comprises a means for switching the switching valve by receiving a switching signal.

The present invention also provides a switching means for switching the switching valve to disconnect the negative flow path switching signal line for transmitting the pressure oil of the auxiliary pump to the hydraulic pressure section of the switching valve, and the negative flow path switching signal line from the controller It is another feature that it is composed of a solenoid valve for opening the negative-conversion channel switching signal line by the no-load operation signal applied. In addition, the present invention may be configured such that the pressure oil of the auxiliary pump is also supplied to the pump regulator in the case of the solenoid valve.

Hereinafter, with reference to the accompanying drawings an embodiment of the hydraulic control device of the excavator according to the present invention will be described in detail.

The hydraulic control apparatus of the excavator according to the present invention, as shown in the hydraulic circuit diagram of Figure 3, the two main pumps (1, 2) and the pressure oil discharged from each of the main pumps (1, 2) toward a plurality of working machines An orifice 9c provided on the flow paths 9a and 10a branched from the main control valve 3 for flow control and the center bypass lines 4 and 5 passing through the main control valve 3 and connected to the drain tank; 10c) and the negative load line 4a, 5a connected to the pump regulators 6, 7 of the main pumps 1, 2 at the center bypass line 4, 5, and the no-load operation state of the excavator. And a controller 8 which adjusts the engine speed to the minimum by the no-load driving signal detected by the no-load driving detection means.

The present invention bypasses the orifices (9c, 10c) and bypass flow paths (9d, 10d) and the bypass flow paths (9d, 10d) connecting the downstream side of the center bypass line (4, 5) and the drain tank. It further comprises a switching valve 9, 10 for blocking or communicating, the switching valve 9, 10 is switched by a switching signal applied from the controller 8 when a no load call is detected from the no-load operation detecting means. Then, the pressure oil of the main pumps 1 and 2 via the center bypass lines 4 and 5 is immediately drained through the bypass passages 9d and 10d to the drain tank.

The no-load operation detecting means sequentially passes the pressure oil of the auxiliary pump 11 through the front work device control spools 3a, 3b, 3c, 3d, 3e, 3f, and 3g of the main control valve 3, and drain line R. The front operation detection signal line Px to be drained to the drain and the driving detection signal line Py to drain the hydraulic oil of the auxiliary pump 11 in order through the driving control spools 3h and 3i of the main control valve 3. And a pressure switch 14 for detecting a line pressure applied to at least one sensing signal line of the front job sensing signal line Px or the traveling sensing signal line Py and transmitting the detected line pressure to the controller 8.

As shown in FIG. 3, the no-load driving detection means of the present invention selects a high signal pressure among signal pressures detected in the front work detection signal line Px and the driving detection signal line Py, respectively. 14 may further include a shuttle valve 15 to be delivered.

And the no-load driving detection means, as shown in Figure 4, transfers the signal pressure detected in the front work detection signal line (Px) and the driving detection signal line (Py) to each of the pressure switch (14a, 114b) The pressure switch 14a or 14b may be configured to transmit a signal to the controller 8.

According to the present invention, the switching valves 9 and 10 communicate with the bypass flow paths 9d and 10d by the no-load operation signal detected by the no-load operation detecting means, so that the flow rate of the center bypass lines 4 and 5 is flow resistance. It is characterized in that it is provided with a negative flow path switching means for draining the tank immediately without water.

As shown in FIG. 3, the negative cone flow path switching means includes a negative flow path switching signal line 16 which transfers the pressure oil of the auxiliary pump 11 to the hydraulic pressure parts of the switching valves 9 and 10, and The solenoid valve 17 which blocks the negative flow path switching signal line 16 and opens the negative flow path switching signal line 16 by a no-load operation signal transmitted from the pressure switch 14 through the controller 8. It is composed of

In addition, the hydraulic controller of the present invention selects a high signal pressure of the negative cone pressure and adjusts the pump regulators 6 and 7 so that the swash plate angle of the main pumps 1 and 2 is adjusted to the minimum position by the selected signal pressure. It further comprises a pump swash plate control means.

The main pump swash plate control means has a high negative pressure acting through the negative cone flow path switching signal acting through the flow path branched from the negative cone flow path switching signal line 16 and the negative cone pressure acting through the negative cone lines 4a and 5a. It consists of shuttle valves 18a and 18b which select the signal pressure and apply the signal pressure to the pump regulators 6 and 7.

The hydraulic control apparatus of the present invention configured as described above operates as follows.

When the excavator travels or performs front work, the front control detection signal line (Px) or travel detection signal line (Py) for switching the control spool of the main control valve (3) to the operating position and bypassing the control spool. And a center bypass line 4 and 5, and thus a signal pressure is formed in the front job detection signal line Px or the traveling detection signal line Py, which is blocked so that an excavator is presently present at the pressure switch 14. The negative pressure of the negative cone lines 4a and 5a is lowered while the center bypass lines 4 and 5 of the main control valve 3 are cut off while the signal pressure indicating the operation is applied. After selecting from the shuttle valves 18a and 18b, the pump regulators 6 and 7 are controlled to maximize the discharge flow rates of the main pumps 1 and 2.

On the other hand, when the excavator does not run and does not perform the front work, the discharge flow rates of the main pumps 1 and 2 are minimized, and the engine also rotates at the minimum rotation speed under no load. In this case, since no control spool of the main control valve 3 is placed in the neutral position without shifting the position, the discharge flow rates of the main pumps 1 and 2 are all the center bypass lines 4 and 5 of the main control valve 3. The discharge flow rate of the auxiliary pump 11 passing through the front job detection signal line Px and the driving detection signal line Py is drained to the tank along the drain line R, so that these front job detections are detected. The signal pressure is not generated in the signal line Px and the driving detection signal line Py.

As a result, the pressure switch 14 does not transmit any signal to the controller 8. When this state continues for a certain time, the controller 8 detects that the excavator is in a no-load operation state and transmits a no-load operation signal to the solenoid portion of the solenoid valve 17 and the governor 19 of the engine.

Thus, the solenoid valve 17 which received the no-load operation signal from the controller 8 switches to the left side of FIG. 3, and opens the signal conversion line 16 to the negative-cone oil, and the pressure oil of the auxiliary pump 11 switches to the negative-cone oil. Through the signal line 16 acts on the hydraulic pressure portion of the switching valve (9, 10) that is a negative-cone pressure sensing means, it is supplied to the shuttle valve (18a, 18b).

In this case, the switching valves 9 and 10 receive a switching signal with negative cone oil and switch to the lower side of FIG. 3 to transfer the center bypass lines 4 and 5 to the drain line R through the bypass passages 9d and 10d. Communicate. Accordingly, the pressure oil of the main pumps (1, 2) passing through the center bypass line (4, 5) drains straight into the tank without flow resistance, while the pump pressure is lowered to the back pressure of the tank, and the pump is operated at almost no load. . In addition, a high pressure is selected between the negative cone pressure of the negative cone lines 4a and 5a connected to the center bypass lines 4 and 5 and the negative cone flow channel switching signal pressure of the negative cone switching signal line 16. By acting on 6,7, the discharge flow rate of the main pumps 1, 2 is reduced to a minimum, and at the same time, the governor 19 of the engine, which has received the no-load operation signal from the controller 8, changes the engine speed. Lowered to the lowest, the engine consumes the lowest fuel consumption.

In addition, when the excavator does not run or do no front work, the hydraulic oil of the main pumps 1 and 2 passing through the center bypass lines 4 and 5 passes through the bypass passages 9d and 10d of the switching valves 9 and 10. Since it is drained straight into the tank without flow path resistance through), it is possible to reduce the noise of the excavator by preventing abnormal noise generated when passing through the orifice of the conventional negative cone valve.

As described above, in the hydraulic control device of the present invention, if the excavator does not run or front work for a predetermined time, the controller detects this as the no-load operation state and lowers the engine speed by the no-load operation signal to the minimum. And the engine is operated under no load state with the minimum swash angle of the pump, so that the fuel consumption of the engine can be minimized to achieve high fuel efficiency, and the main pumps (1, 2) passing through the center bypass line (4, 5) ) 'S pressure oil is drained directly into the tank through the bypass flow paths 9d and 10d of the switching valves 9 and 10 without flow resistance, thereby preventing abnormal noise generated when passing through the orifice of the conventional negative cone valve. Can be angry.

Claims (3)

At least one main pump (1, 2), a main control valve (3) for controlling the flow of pressurized oil discharged from the main pumps (1, 2) to a plurality of working machines, and the main control valve (3) Orifices 9c and 10c branched from the through center bypass lines 4 and 5 and connected to the drain tanks 9a and 10a and the main pumps in the center bypass lines 4 and 5, respectively. To the negative cone line 4a, 5a connected to the pump regulators 6 and 7, and the no-load operation detection means for detecting the no-load operation state of the excavator, and the no-load operation signal detected by the no-load operation detection means. In the hydraulic control device of an excavator including a controller (8) for adjusting the engine speed to a minimum by Bypass passages 9d and 10d for bypassing the orifices 9c and 10c and connecting the downstream side of the center bypass line 4 and 5 to the drain tank, and the bypass passages 9d and 10d are blocked or communicated. And a means for switching the switching valves 9 and 10 by receiving a switching signal from the controller 8 when an unloaded call is detected from the no-load operation detecting means. Hydraulic control equipment of excavator. The switching means of the switching valve (9, 10) and the negative-conductor switching signal line (16) for transmitting the pressure oil of the auxiliary pump (11) to the hydraulic pressure section of the switching valve (9, 10); And a solenoid valve 17 for blocking the negative flow path switching signal line 16 and opening the negative flow path switching signal line 16 by a no-load operation signal applied from the controller 8. Hydraulic control device of the excavator. The hydraulic control apparatus of an excavator according to claim 2, wherein the pressure oil of the auxiliary pump (11) is configured to be supplied to the pump regulator (6, 7) via the solenoid valve (17).