JP3421076B2 - Directional valve drive hydraulic circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control valve hydraulic drive circuit for driving a directional control valve for driving and controlling a hydraulic actuator of a construction machine such as a hydraulic excavator with pilot pressure, and in particular, it is driven by a hydraulic actuator. The present invention relates to a directional switching valve drive hydraulic circuit suitable when the load body is an inertial body.

[0002]

2. Description of the Related Art FIGS. 4 and 5 are views showing a schematic construction of a hydraulic excavator cited as an example of a construction machine having an inertial body, FIG. 4 is a side view and FIG. 5 is a plan view. The hydraulic excavator shown in these figures has a revolving structure 1 arranged at an upper part, a traveling structure 2 arranged at a lower part, a revolving motor 3 for revolving the revolving structure 1, and left and right crawler belts 4 constituting the traveling structure 2. , 6 and
The left and right traveling motors 5 and 7 for traveling the traveling body 2, the boom 8 rotatably provided at the front position of the revolving structure 1, the arm 9 rotatably provided on the boom 8, and the arm 9 The bucket 10 is provided so as to be rotatable, a boom cylinder 11 that drives the boom 8, an arm cylinder 12 that drives the arm 9, and a bucket cylinder 13 that drives the bucket 10. The swing motor 3, traveling motors 5, 7, boom cylinder 11, arm cylinder 12, and bucket cylinder 13 described above constitute a hydraulic actuator. The boom 8, the arm 9 and the bucket 10 described above form the front. The front and the revolving superstructure 1 constitute an inertial body which is a heavy actuating body.

FIG. 6 is a circuit diagram showing a conventional directional control valve drive hydraulic circuit provided in the hydraulic excavator described above, and FIG. 7 is a cross section of a flow control valve with pressure compensation provided in the directional control valve drive hydraulic circuit shown in FIG. This is shown in Japanese Utility Model Publication No. 1-163201 (Japanese Utility Model Application No. 63-60030).

This prior art controls a hydraulic pump 15 which is a main pump and a flow of pressure oil supplied from the hydraulic pump 15 to the boom cylinder 11, and has a directional control valve having pilot chambers 16a and 16b on both left and right sides. 16, a tank 17, a pipe line 18a for connecting the direction switching valve 16 and the bottom side 11b of the boom cylinder 11, and a direction switching valve 16
And a pipe line 18b connecting the rod side 11a of the boom cylinder 11 with each other. Further, the pilot hydraulic pump 21, the relief valve 22 that regulates the discharge pressure of the pilot hydraulic pump 21, that is, the pilot pressure, the operation lever 23 that operates the drive of the boom cylinder 11, and the pilot valve 2 that is switched by the operation lever 23.
4 and. The pilot valve 24 includes two chambers 25a and 25b, spools 26a and 26b inserted into the chambers 25a and 25b, and a push rod 27 connected to the spools 26a and 26b.
a, 27b, pilot hydraulic pump 21 and each chamber 25
a passage 28 connecting the a and 25b, a passage 29 connecting the tank 17 and the chambers 25a and 25b, and the directional control valve 1
6 pilot chambers 16a and 16b, and chamber 25
Passage 3 for connecting with a and 25b respectively
0a and 30b.

Further, the direction switching valve 16 and the pilot valve 24
And a flow rate control valve, for example, pressure control flow rate control valves 53a and 53b with pressure compensation, and a pilot line 36a1 connecting the flow rate control valve 53a and the pilot valve 24.
, A pilot line 36b1 connecting the flow control valve 53b and the pilot valve 24, a pilot line 36a2 connecting the flow control valve 53a and the pilot chamber 16a of the direction switching valve 16, a flow control valve 53b and the direction switching. Pilot line 36b connecting the pilot chamber 16b of the valve 16
2 and.

The above-mentioned flow control valve 53a with pressure compensation is
As shown in FIG. 7, a port 37a to which the pilot conduit 36a1 is connected, a port 38a to which the pilot conduit 36a2 is connected, and a spool 39a having a throttle 40a.
And the oil chambers 41a and 42a formed on both sides of the throttle 40a.
And the springs 43a, 4 arranged on both sides of the spool 39a.
4a, a hole 45a provided so as to penetrate through the spool 39a in the radial direction, and communicating with the oil chamber 41a, and a port 37a.
An annular groove 46a formed continuously with the port 38a, an annular groove 47a formed continuously with the port 38a, lands 48a and 49a with which the spool 39a is in sliding contact, and a spool 50a arranged at the end of the spring 43a. , The pilot conduit 5 communicating with the passage 30b of the pilot valve 24 shown in FIG.
2a is connected to the pilot chamber 51a.

Another flow control valve 53b with pressure compensation
Port 37 to which the pilot line 36b1 is connected
b, the port 38 to which the pilot conduit 36b2 is connected
b, a pilot chamber 51b to which a pilot conduit 52b communicating with the passage 30a of the pilot valve 24 is connected,
The flow control valve 53a has the same structure as the flow control valve 53a described above.

The operation in this conventional technique is as follows. For example, when the operation lever 23 is tilted to the left side in FIG. 6, the spool 26a descends via the push rod 27a, and the pressure oil discharged from the pilot hydraulic pump 21 passes through the passage 28, the chamber 25a, the passage 30a, and the pipeline 36a1. It is supplied to the port 37a of the flow control valve 53a. This oil is used for the annular groove 46a, the hole 45a, and the oil chamber 41 shown in FIG.
After passing through a, it passes through the throttle 40a and is guided to the oil chamber 42a. At this time, if the amount of oil passing through the throttle 40a increases, the throttle 40
When a differential pressure is generated on both sides of a and the differential pressure becomes larger than the spring force of the spring 44a, the spool 39a in the neutral position as shown in the drawing moves to the left in FIG. Therefore, oil is supplied to the pilot chamber 16a of the directional control valve 16 through the annular grooves 46a and 47a, the port 38a and the pilot conduit 36a2 shown in FIG. As a result, the directional control valve 16 starts to operate. When the direction switching valve 16 is switched from the neutral position to the left position, the hydraulic pump 15
Pressure oil is supplied to the rod side 11a of the boom cylinder 11 via the direction switching valve 16 and the conduit 18b, the boom cylinder 11 contracts, and the boom 8 shown in FIG. 4 descends.

When the operation lever 23 shown in FIG. 6 is returned to the neutral position from such a state, the chamber 2 of the pilot valve 24 is
5a communicates with the tank 17. Therefore, the port 37a, the annular groove 46a, the hole 45a, and the oil chamber 41a shown in FIG. 7 are conducted to the tank 17, and the pressure on the oil chamber 42a side is changed to the oil chamber 41a.
Higher than side pressure. As a result, the oil supplied to the pilot chamber 16a of the directional control valve 16 shown in FIG.
It flows into the flow control valve 53a from the port 38a. This oil passes from the oil chamber 42a shown in FIG. 7 through the throttle 40a, passes through the oil chamber 41a, the hole 45a, the annular groove 46a, the port 37a, the pilot line 36a1, the pilot valve 24, and the tank 1
It flows to 7. At this time, when the amount of oil passing through the throttle 40a increases and the differential pressure on both sides of the throttle 40a becomes larger than the spring force of the spring 43a, the spool 39a moves leftward to pass oil again. By repeating such an operation within a short time, the spool 39a is stopped at a position where a flow rate at which the above-mentioned differential pressure generated in the throttle 40a and the spring force of the spring 43a balance each other finally occurs. That is, the flow rate control valve 53a passes through the pilot chamber 16a and the pilot pipe line 36a2 shown in FIG.
4. The flow rate of oil flowing into the tank 17 is constant.
Therefore, even if the operation lever 23 is suddenly returned to the neutral position, the return speed of the direction switching valve 16 is slow, and the directional switching valve 16 is gently returned to the neutral position.

When the return speed of the directional control valve 16 to the neutral position is limited as described above, the lines 18a and 18b are not shut off rapidly, and the brake pressure generated in the lines 18a and 18b is also increased. It becomes loose. Therefore, the impact applied to the entire body of the hydraulic excavator at the time of stop is mitigated, the operability and the durability of the machine are improved, and the feeling of fatigue given to the operator who operates the operation lever 23 can be reduced.

The reverse operation of the operating lever 23 is as follows. For example, the operating lever 23 is moved to the left side of FIG.
6a2 enters the pilot chamber 16a, the direction switching valve 16 is switched to the left position, the oil discharged from the pump 15 is supplied to the rod side 11a of the boom cylinder 11 through the pipe line 18b, and the boom 8 descends. In the middle, operating lever 2
When 3 is suddenly moved beyond the neutral position to the right stroke end, the discharge oil of the pilot pump 21 is supplied to the port 37b of the flow control valve 53b through the passage 28, the chamber 25b, the passage 30b, and the pipeline 36b1. It This oil passes through the flow control valve 53b without resistance, and the port 38b,
It is supplied to the pilot chamber 16b of the directional control valve 16 via the pilot conduit 36b2.

At this time, the pressure oil of the pilot pump 21 is simultaneously guided to the pilot conduit 52a through the conduit 36b1, and the oil in the pilot chamber 16a of the direction switching valve 16 returns to the tank 17 in the flow control valve. The pilot room 51a of 53a is reached. This pressure oil is used for the spool 5 shown in FIG.
0a to the left, and the spool 39a through the spring 43a.
a is moved to the left against the spool return force due to the differential pressure generated by the spring 44a and the throttle 40a, and the flow control function of the flow control valve 53a is blocked. In this state, the oil in the pilot chamber 16a flows into the pipeline 36a.
2, without any resistance from the port 38a through the annular grooves 47a, 46a into the port 37a, the pipe 36a1, the passage 3
Return to the tank 17 through 0a and the chamber 25a. Therefore, the direction switching valve 16 is switched to the left direction relatively quickly, and the oil discharged from the pump 15 passes through the pipe line 18a and the boom cylinder 11
Flows into the bottom side 11b of the boom 8 and the boom 8 shown in FIG. 4 starts to rise with almost no time delay. Also,
If the operating lever 23 is suddenly operated to the left from such a state, the flow control function of the flow control valve 53b is blocked in the same manner as described above, and the flow control valve 53b starts descending with almost no time delay, and is relatively smooth. The boom can be raised and lowered.

As described above, in the above-mentioned conventional technique, there is relatively little time delay in the reverse operation command, for example, continuous operation such as boom raising to boom lowering or boom lowering to boom raising, and the size of the diaphragm 40a is large. This continuous operation can be performed regardless of the size, and therefore the aperture 40a can be set sufficiently small. As a result, the return speed of the directional control valve 16 at the time of a sudden stop in the boom raising or boom lowering independent operation can be sufficiently slowed down, and as described above, the shock applied to the entire vehicle body at the time of stopping can be alleviated. Since the durability of the machine can be improved, the operator's feeling of fatigue can be reduced, and a sudden reverse operation can be performed, there is an advantage that the pressing operation of the ground surface by the bucket and the like can be realized at the same time.

[0014]

By the way, in the hydraulic excavator and the like shown in FIGS. 4 and 5, the operating lever 23 of the pilot valve 24 shown in FIG. 6 is arranged in the seat portion of the driver's seat. The directional control valve 16 is arranged substantially in the center of the revolving superstructure 1, and the tank 17 includes the directional control valve 16
It is located near. Hydraulic excavator is for example 20t
If it is of the on class, the conduits 36a1 and 36a2 for connecting the pilot valve 24 and the pilot chambers 16a and 16b of the directional control valve 16 or the conduits 36b1 and 36b2.
Are 3 to 4 m, respectively, and the pipelines to the pilot valve 24 and the tank 17 are 4 to 5 m.

In the prior art shown in FIG. 6 described above, when the directional control valve 16 is switched in the reverse direction by the operation of the abrupt reverse lever, the pressure pushed out from the pilot chamber 16a or 16b of the directional control valve 16 is changed. The oil is pipe 36a2,
Flow control valve 53a and flow path 3 with the flow control function disabled
6a1, or through the pipe line 36b2, the flow rate control valve 53b in which the flow rate control function is disabled, and the pipe line 36b1 to the pilot valve 24, and further the pilot valve 24
Out into the tank 17.

Therefore, the pipelines 36aa1, 36a2
When the pressure in the pipes connected to 36b1, 36b2 and the tank 17 is low, the pressure oil smoothly flows in the pipes, and the directional control valve 16 is relatively swiftly switched to realize a desired rapid reverse operation. However, depending on the type of hydraulic excavator, due to the length of the pipe line, the directional control valve 16 is not supported during continuous sudden reverse operation or when the ambient temperature is low. This causes a problem that pressure rises and the followability of the switching operation of the direction switching valve 16 with respect to the operation of the operation lever 23 deteriorates. There is also a problem that back pressure is applied to the directional control valve 16 and back pressure is applied to the pilot valve 24, and the operation feeling of the operating lever for operating the pilot valve 24 becomes heavy.

The present invention has been made in view of the above-mentioned circumstances in the prior art, and its purpose is to perform a quick reverse operation of an operating lever, a continuous direction reverse operation, and a directional control valve even at a low temperature. Another object of the present invention is to provide a directional control valve drive hydraulic circuit that can suppress the back pressure of the pilot valve.

[0018]

To achieve this object, the present invention provides a directional control valve for controlling the drive of a hydraulic actuator, and an operating lever for operating the directional control valve.
The pilot valve that interlocks with this operating lever, and the pilot valves that are located on the left and right sides of this pilot valve and the above-mentioned directional control valve.
Provided with a pair of pilot lines connecting the bets chamber respectively, each of the pilot lines of these,
The pilot of the directional control valve from the pilot valve
Freely passes the pressure oil to the chamber, the path of the directional control valve
In the directional control valve drive hydraulic circuit that is equipped with a flow control valve that can restrict the flow of pressure oil from the pilot chamber to the pilot valve, in the pilot chambers on the left and right sides of the directional control valve.
In each of the pilot pipes located between the flow control valve and each of the flow control valves, a communication means for selectively communicating these pilot pipes with the tank according to the abrupt reverse operation of the operation lever is provided . Accompanying the sudden reverse operation of the operating lever
The pilot valve and the flow control valves
One of the respective pilot lines located between
The pilot pressure generated in the pilot line on one side is
To the communication means provided in the pilot line of
It is constructed so as to be guided as a pressure for operating the passage means .

[0019]

Since the present invention has the above-mentioned structure, when the operating lever is suddenly reversed, the communication means is activated and the pilot line portion located between the direction switching valve and the flow control valve is connected to the tank. The length of the pipe that communicates and connects the pipe portion and the directional control valve is sufficiently shorter than the length of the pipe that connects the pilot valve and the directional control valve. It is possible to suppress the occurrence of back pressure in the directional control valve even during reverse operation or at low temperature. Accordingly, the directional control valve can be switched with a small pilot pressure, and the back pressure of the pilot valve can be suppressed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the directional control valve drive hydraulic circuit of the present invention will be described below with reference to the drawings. 1 is a circuit diagram showing a first embodiment of a directional control valve drive hydraulic circuit of the present invention, and FIG. 2 is a sectional view of a flow control valve with pressure compensation provided in the directional control valve drive hydraulic circuit shown in FIG. . This first embodiment is provided, for example, in a hydraulic excavator as shown in FIGS. 4 and 5 described above, FIG. 1 is drawn corresponding to FIG. 6 described above, and FIG. 2 is described above. It is drawn according to 7.

That is, also in the first embodiment, the hydraulic pump 15 as the main pump, the boom cylinder 11 for driving the boom 8 shown in FIG. 4, and the hydraulic oil supplied from the hydraulic pump 15 to the boom cylinder 11 are used. A directional control valve 16 that controls the flow and has pilot chambers 16a and 16b on both left and right sides, a tank 17, a conduit 18a that connects the directional control valve 16 and the bottom side 11b of the boom cylinder 11, and a directional control valve 16. It is provided with a pipe line 18b which communicates with the rod side 11a of the boom cylinder 11. Further, the pilot hydraulic pump 21, the relief valve 22 that regulates the discharge pressure of the pilot hydraulic pump 21, and the boom cylinder 1
An operation lever 23 for operating the drive of No. 1 and a pilot valve 24 that is switched by the operation lever 23 are provided. The pilot valve 24 has two chambers 25a and 25b.
And spools 26a and 26b inserted in the chambers 25a and 25b, and spools 26a and 26b,
Push rods 27a and 27b connected to 26b,
A passage 28 that connects the pilot hydraulic pump 21 and the chambers 25a and 25b, a passage 29 that connects the tank 17 to the chambers 25a and 25b, the pilot chambers 16a and 16b of the directional control valve 16, and the chamber 25a. , 25b, respectively, and passages 30a, 30b for communicating with the corresponding ones.

Further, the direction switching valve 16 and the pilot valve 24
And a flow rate control valve, for example, pressure control flow rate control valves 68a and 68b, and a pilot line 36a1 connecting the flow rate control valve 68a and the pilot valve 24.
A pilot line 36b1 connecting the flow control valve 68b and the pilot valve 24, a pilot line 36a2 connecting the flow control valve 68a and the pilot chamber 16a of the direction switching valve 16, a flow control valve 68b and the direction switching. Pilot line 36b connecting the pilot chamber 16b of the valve 16
2 and.

The flow control valve 68a with pressure compensation described above is
The spool 50a is removed from the configuration of the flow control valve 53a with pressure compensation shown in FIG. 7 described above, and the flow control valve 53a has the same configuration as that in which the pilot chamber 51a is closed without being provided. That is,
The flow control valve 68a includes a port 67a1 to which the pilot conduit 36a1 is connected, a port 67a2 to which the pilot conduit 36a2 is connected, a spool 69a having a throttle 70a, and oil chambers 71a formed on both sides of the throttle 70a.
72a and springs 73 arranged on both sides of the spool 69a
a, 74a, a hole 75a provided to penetrate the spool 69a in the radial direction and communicating with the oil chamber 71a, an annular groove 76a formed continuously with the port 67a1, and a port 67a2 continuously formed. And an annular groove 77a and lands 78a and 79a with which the spool 69a is in sliding contact. The other pressure compensation flow rate control valve 68b is also provided with a port 67b1 to which the pilot line 36b1 is connected, a port 67b2 to which the pilot line 36b2 is connected, etc., and is formed in the same structure as the flow rate control valve 68a described above. is there.

In particular, in the first embodiment, the flow path control valve 68a has a conduit 63 communicating with the port 67a2.
a, an oil chamber 62a communicating with the tank 17, and a conduit 63a
And a spool 61a for selectively connecting the oil chamber 62a with the oil chamber 62a,
A spring 64a for urging the spool 61a, and a spring 64a
The oil chamber 6 formed at the end portion on the spool 61a side that opposes a
5a, a pipeline 60a connecting the pilot pipeline 36b1 and the oil chamber 65a is provided. Similarly, the flow control valve 68
In b, a pipe line 63b communicating with the port 67b2, an oil chamber 62b communicating with the tank 17, a pipe line 63b and an oil chamber 62.
b, a spring 64b for urging the spool 61b, an oil chamber 65b formed at the end of the spool 61b facing the spring 64b, a pilot conduit 36a1 and an oil chamber 65b. Conduit 6 connecting with
0b is provided.

The above-mentioned pipeline 63a, oil chamber 62a, spool 61a, spring 64a, oil chamber 65a, and pipeline 60
The symbol “a” constitutes a communication means for selectively communicating the pilot conduit 36a2 located between the direction switching valve 16 and the flow rate control valve 68a with the tank 17 when the operation lever 23 is suddenly reversed. Also, the above-mentioned pipe line 63b and the oil chamber 6
2b, spool 61b, spring 64b, oil chamber 65b
And the conduit 60b are connected to the direction switching valve 16 and the flow control valve 68.
It constitutes a communication means for selectively communicating the pilot pipe line 36b2 located between b and b with the tank 17 when the operation lever 23 is suddenly reversed.

The operation of the first embodiment thus constructed is as follows. For example, when the operation lever 23 is tilted to the left side in FIG. 1, the spool 26a is lowered via the push rod 27a, and the pressure oil discharged from the pilot hydraulic pump 21 is in the passage 28, the chamber 25a, the passage 30a, and the pipeline 3.
It is supplied to the port 67a1 of the flow control valve 68a via 6a1. This oil is contained in the annular groove 76a and the hole 7 shown in FIG.
5a, the oil chamber 71a, the throttle 70a, and the oil chamber 72a.
Be led to. At this time, when the amount of oil passing through the throttle 70a increases, a differential pressure is generated on both sides of the throttle 70a, and when this differential pressure becomes larger than the spring force of the spring 74a, the spool 69a in the neutral position as shown in the figure. Move 2 to the left. Therefore, oil is supplied to the pilot chamber 16a of the direction switching valve 16 through the annular grooves 76a and 77a, the port 67a2, and the pilot conduit 36a2 shown in FIG. As a result, the directional control valve 16 starts to operate. And
When the direction switching valve 16 is switched from the neutral position to the left side position, the pressure oil of the hydraulic pump 15 is transferred to the direction switching valve 16 and the conduit 18.
It is supplied to the rod side 11a of the boom cylinder 11 via b, the boom cylinder 11 contracts, and the boom 8 shown in FIG. 4 descends.

When the operating lever 23 shown in FIG. 1 is returned to the neutral position from such a state, the chamber 2 of the pilot valve 24 is
5a communicates with the tank 17. Therefore, the port 67a1, the annular groove 76a, the hole 75a, and the oil chamber 71a shown in FIG.
Is connected to the tank 17, and the pressure on the oil chamber 72a side is
It becomes higher than the pressure on the a side. As a result, the oil supplied to the pilot chamber 16a of the directional control valve 16 shown in FIG. 1 flows into the flow control valve 68a from the port 67a2.
This oil passes from the oil chamber 72a shown in FIG. 2 through the throttle 70a, and the oil chamber 71a, the hole 75a, the annular groove 76a, and the port 67.
It flows to the tank 17 through a1, the pilot pipe line 36a1, and the pilot valve 24. At this time, the amount of oil passing through the throttle 70a increases, and the differential pressure on both sides of the throttle 70a is increased by the spring 7.
When it becomes larger than the spring force of 3a, the spool 69a moves leftward to pass oil again. By repeating such an operation within a short time, the spool 69a is stopped at a position where a flow rate at which the above-described differential pressure generated in the throttle 70a and the spring force of the spring 73a are finally balanced. That is, the flow rate of the oil flowing from the flow rate control valve 68a to the pilot line 36a1, the pilot valve 24, and the tank 17 via the pilot chamber 16a and the pilot line 36a2 shown in FIG. Therefore, the direction switching valve 16 is operated by the operation lever 2
Even if 3 is suddenly returned to the neutral position, its return speed is slow,
Gently return to the neutral position.

When the return speed of the directional control valve 16 to the neutral position is limited as described above, the lines 18a and 18b are not shut off rapidly, and the brake pressure generated in the lines 18a and 18b is also increased. It becomes loose. Therefore, the impact applied to the entire body of the hydraulic excavator at the time of stop is mitigated, the operability and the durability of the machine are improved, and the feeling of fatigue given to the operator who operates the operation lever 23 can be reduced. The above operation is almost the same as that of the prior art shown in FIGS. 6 and 7 described above.

The reverse operation of the operating lever 23 is as follows. For example, the operating lever 23 is moved to the left side in FIG.
6a2 enters the pilot chamber 16a, the direction switching valve 16 is switched to the left position, the oil discharged from the pump 15 is supplied to the rod side 11a of the boom cylinder 11 through the pipe line 18b, and the boom 8 descends. In the middle, operating lever 2
When 3 is rapidly moved beyond the neutral position to the right stroke end, the discharge oil of the pilot pump 21 is supplied to the port 67b1 of the flow rate control valve 68b through the passage 28, the chamber 25b, the passage 30b, and the pipeline 36b1. It This oil passes through the flow control valve 68b without resistance, and flows through the port 67b.
2. It is supplied to the pilot chamber 16b of the direction switching valve 16 via the pilot pipe line 36b2.

At this time, the pressure oil of the pilot pump 21 is simultaneously guided to the oil chamber 65a formed in the flow rate control valve 68a through the pipe line 60a. This pressure oil is the spring 64a.
The spool 61a is pushed to the left against the force of, and the pipe line 63a, which has been blocked until then, and the oil chamber 62a are made to communicate with each other. As a result, the pilot conduit 36a2 and the tank 17
Are connected to the pipeline 63a via the oil chamber 62a, and the oil in the pilot chamber 16a of the directional control valve 16 is connected to the pipeline 36a2,
It returns to the tank 17 through the pipe line 63a and the oil chamber 62a. Therefore, the direction switching valve 16 is rapidly switched to the left, and the oil discharged from the pump 15 passes through the pipe line 18a and flows into the bottom side 11b of the boom cylinder 11, and the boom 8 shown in FIG.
Begins to rise with no time delay. Further, when the operating lever 23 is suddenly operated to the left side from such a state, the spool 61b on the flow control valve 68b side is moved in the same manner as described above, and the pilot chamber 16 of the direction switching valve 16 is moved.
The oil of b is returned to the tank 17 via the pipe line 36b2, the pipe line 63b, and the oil chamber 62b, and the boom 8 starts descending without a time delay. By repeating this operation, a relatively smooth boom raising / lowering operation can be performed.

In the first embodiment thus constructed, when the operating lever 24 is suddenly reversed, the spool 61a or the spool 61b operates as described above, and the direction switching valve 16 and the flow rate control valves 68a, 68b are operated. pilot line 36a2 or 36 b2 located between the tank 1
7, the length of these pipe lines 36a2, 36b2 is sufficiently shorter than the length of the whole pipe line connecting the pilot valve 24 and the directional control valve 16, and therefore continuous rapid reverse operation is performed. The generation of back pressure in the pilot valves 16a and 16b of the directional control valve 16 can be suppressed even at low temperature and low temperature, and good followability of the switching operation of the directional control valve 16 with respect to the operation of the operating lever 23 can be obtained. . Further, since the back pressure in the pilot chambers 16a and 16b of the direction switching valve 16 can be reduced, the direction switching valve 16 can be switched with a small pilot pressure, and thus the back pressure of the pilot valve 24 can be suppressed. The operation feeling of the operation lever 23 at the time of this sudden reverse operation can be lightened.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. In the second embodiment, the flow rate control valve 53a shown in FIG. 6 and FIG.
53b is provided. And a pilot conduit 36b1 connecting the pilot valve 24 and the flow control valve 53b,
One end is connected to a pilot conduit 52a that connects the pilot chamber 51a of the flow rate control valve 53a, and the other end is connected to the oil chamber 65a.
A pipeline 66a connected to a is provided, and a pilot pipeline 36a1 connecting the pilot valve 24 and the flow control valve 53a, and a pilot chamber 51 of the flow control valve 53b.
the pilot line 52b connecting the b is connected at one end is provided with a conduit 66 b which is connected at the other end to the oil chamber 65b. The other structure is similar to that of the first embodiment.

In the second embodiment, in addition to the same effects as the first embodiment, the operation lever 2 is used.
3 is tilted to the left to supply pressure oil to the pilot chamber 16a of the directional control valve 16 from the state where pressure oil is supplied to the pilot chamber 16a of the directional control valve 16 by rapidly tilting the operating lever 23 to the right. The pilot line 36b
1. Pilot chamber 50a via pilot conduit 52a
The pressure oil is also guided to move the spool 50a to the left in FIG. 3, thereby moving the spool 39a to the left, and the flow control function of the flow control valve 53a is disabled. Therefore, in addition to the communication between the pilot conduit 36a2 and the tank 17 due to the movement of the spool 61a in the direction of FIG. 3 as described above, the port 3 of the flow control valve 53a is also added.
7a and the port 38a are in communication with each other. The same applies to the operation on the side of the flow control valve 53b when the operating lever 23 is rapidly tilted to the left from the above state.

The pilot conduit 52a, the pilot chamber 51a, and the spool 50a described above constitute a blocking means for selectively blocking the flow rate control by the flow rate control valve 53a in accordance with the operation of tilting the operating lever 23 to the right. Pilot line 52b, pilot chamber 51b, spool 50b
Constitutes a blocking means for selectively blocking the flow rate control by the flow rate control valve 53b when the operation lever 23 is tilted to the left.

In the second embodiment thus constructed, the direction switching valve 16 is operated when the operating lever 23 is suddenly reversed.
Each of the pilot conduits 36a2, 36b2 connected to the pilot chambers 16a, 16b communicates with the tank 17, and the flow rate control functions of the flow rate control valves 53a, 53b are disabled, and the ports 37a and 38a of the flow rate control valve 53a are disabled. Communicates with the port 37 of the flow control valve 53b.
b and the port 38b communicate with each other, and the directional switching valve 16 can be switched more quickly due to their synergistic effect, and a superior followability of the switching operation of the directional switching valve 16 with respect to the operation lever 23 can be obtained.

[0036]

As described above, according to the present invention, the back pressure of the directional control valve and the pilot valve is generated at the time of the sudden reverse operation of the operating lever even during the continuous sudden reverse operation or at the time of low temperature. it can be suppressed, the effect that can be able to obtain a good followability of the switching operation of the directional control valve, to reduce the operation feeling of the operation levers during the rapid reverse operation in conjunction with respect to the operation of the operating lever is there.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a directional control valve drive hydraulic circuit of the present invention.

FIG. 2 is a sectional view of a flow control valve with pressure compensation provided in the directional control valve drive hydraulic circuit shown in FIG.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a side view showing a schematic configuration of a hydraulic excavator taken as an example of a construction machine.

5 is a plan view of the hydraulic excavator shown in FIG. 4. FIG.

FIG. 6 is a circuit diagram showing a conventional directional control valve drive hydraulic circuit.

7 is a cross-sectional view of a flow control valve with pressure compensation provided in the directional control valve drive hydraulic circuit shown in FIG.

[Explanation of symbols]

1 revolving structure 2 running bodies 3 swing motor 4 tracks 5 traveling motor 6 tracks 7 Travel motor 8 boom 9 arms 10 buckets 11 boom cylinder 11a Rod side 11b Bottom side 12 arm cylinder 13 bucket cylinders 15 Hydraulic pump 16 directional valve 16a Pilot room 16b Pilot room 17 tanks 18a pipeline 18b pipeline 21 Pilot hydraulic pump 22 Relief valve 23 Operation lever 24 Pilot valve Room 25a 25b room 26a spool 26b spool 27a push rod 27b push rod 28 passages 29 passage 30a passage 30b passage 36a1 Pilot line 36b1 Pilot line 36a2 Pilot line 36b2 Pilot line 37a port 37b port 38a port 38b port 39a spool 40a aperture 41a Oil chamber 42a Oil chamber 43a spring 44a spring 45a hole 46a annular groove 47a annular groove 48a land 49a Land 50a spool 50b spool 51a Pilot room 51b Pilot room 52a Pilot line 52b Pilot line 53a Flow control valve with pressure compensation 53b Flow control valve with pressure compensation 60a pipeline 60b pipeline 61a spool 61b spool 62a oil chamber 62b oil chamber 63a pipeline 63b pipeline 64a spring 64b spring 65a oil chamber 65b oil chamber 66a pipeline 66b pipeline 67a1 port 67a2 port 67b1 port 67b2 port 68a Flow control valve with pressure compensation 68b Flow control valve with pressure compensation 69a spool 70a aperture 71a Oil chamber 72a Oil chamber 73a spring 74a spring 75a hole 76a annular groove 77a annular groove 78a Land 79a Land

Claims (4)

(57) [Claims] 1. A directional control valve for controlling the drive of a hydraulic actuator, and an operating lever for operating the directional control valve,
The pilot valve that interlocks with this operating lever, and the pilot valves that are located on the left and right sides of this pilot valve and the above-mentioned directional control valve.
Provided with a pair of pilot lines connecting the bets chamber respectively, each of the pilot lines of these freely passed through the pressure oil from the pilot valve to said pilot chamber of said directional control valve, In a directional control valve drive hydraulic circuit provided with a flow rate control valve capable of restricting the flow of pressure oil from the pilot chamber of the directional control valve to the pilot valve , the pilot chamber on the left and right sides of the directional control valve and the pilot chamber
In each of the pilot pipes located between the respective flow control valves, a communication means for selectively communicating these pilot pipes with the tank according to the abrupt reverse operation of the operation lever is provided . Due to the sudden reverse operation of the operating lever, the pilot valve
Located between the flow control valve and each of the above
From one of the pilot lines
The generated pilot pressure is provided in the pilot line on the other side.
To the above-mentioned communication means, the pressure for operating this communication means and
The directional control valve drive hydraulic circuit is characterized in that it is configured to be guided by . 2. A blocking means for selectively blocking the flow rate control by the flow rate control valve is provided.
Directional switching valve drive hydraulic circuit described. 3. The pilot chamber of the directional control valve and the flow control valve are respectively connected to the communication means.
The pie located between the above and provided with corresponding communication means.
Oil line that communicates with the pipeline that communicates with the lot pipeline and the tank
And a spool for selectively connecting the pipe line and the oil chamber
And a spring that urges this spool and opposes this spring.
Consists of a separate oil chamber formed at the spool-side end
Between the pilot valve and each flow control valve
Others of each of the above pilot lines located
Connect the pilot line on one side to the pilot line on the one side
Of the communication means provided in
Conduit, and the pilot line of the upper Symbol one side, the other
Of the communication means provided in the pilot line on the side
The directional control valve drive hydraulic circuit according to claim 1, further comprising another pipeline connected to the oil chamber . 4. A directional control valve driving hydraulic circuit according to claim 1, said flow control valve is characterized in that it is a pressure compensated flow control valve.