JPH05223105A - Oil pressure pilot device - Google Patents

Abstract

PURPOSE:To obtain an oil pressure pilot device capable of performing rapid reversing operation of an actuator even it is in a slow switching mode that forces the actuator of a hydraulic work machine to perform slow operation, and capable of switching to a normal mode by a signal. CONSTITUTION:This oil pressure pilot device is provided with a directional switching valve 2, an operating means 9 that controls driving of the directional switching valve 2, and pilot ducts 10a, 10b that connect the directional switching valve 2 to the operating means 9. Throttles 14a, 14b, check valves 15a, 15b, and on-off valves 16a, 16b are respectively provided in parallel with each other in these pilot ducts 10a, 10b. Moreover, on-off valves 16a, 16b are connected to pilot ducts 10b, 10a by means of pilot ducts 12b, 12a respectively, and switching valves 19b, 19a that can select a flow switching mode and a normal mode are provided in pilot ducts 12b, 12a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic work machine such as a hydraulic excavator, and more particularly to a hydraulic pilot device for driving a directional control valve for controlling the drive of an actuator with a hydraulic pilot pressure.

[0002]

2. Description of the Related Art Hydraulic working machines such as hydraulic excavators are provided with actuators such as cylinders and motors, and work is performed by appropriately driving these hydraulic actuators. By the way, the drive of each of the actuators is controlled by a directional control valve connected to each,
These directional control valves are generally used in which the hydraulic pilot pressure is controlled by operating an operating lever and the hydraulic pilot pressure is used to drive the directional control valve.

A hydraulic pilot device using the above-mentioned hydraulic pilot pressure will be described with reference to FIGS. 4 to 6. The configuration shown in FIG. 4 is also disclosed in Japanese Utility Model Laid-Open No. 2-48602. In FIG. 4, 1 is a variable displacement type hydraulic pump which is a main hydraulic source, 2 is a direction switching valve which is interposed between a cylinder 3 which is an actuator and a hydraulic pump 1, and 11 is a hydraulic pressure control valve. A pipe line connecting the pump 1 and the pump port P of the directional control valve 2, 32 is a pipe line 11
In order to regulate the maximum pressure of the pressure oil of the above, the relief valve 2a connected to the pipe 11 is a first pilot chamber provided on one side of the direction switching valve 2 and the other 2b is the other side of the direction switching valve 2. Is provided in the second pilot chamber, 31a and 31b are main pipelines connecting the output side A and B ports of the directional control valve 2 and the cylinder 3, and 9 is a pressure output according to the operation amount of the operation lever 8. First pilot valve 9a, second pilot valve 9
b is an operating means composed of b, 5 is a pilot hydraulic pump which is a pressure oil source for operating the directional control valve 2, and 6 is for supplying the operating oil with pressure oil discharged from the pilot hydraulic pump 5. , 7 is a relief valve connected to the pipe 6 for defining the maximum pressure of the pressure oil in the pipe 6,
a is a first pilot line connecting the first pilot chamber 2a of the directional control valve 2 and the first pilot valve 9a of the operating means 9 and 10b is an operation with the second pilot chamber 2b of the directional control valve 2. Wirings 28a and 28b for transmitting a mode switching signal are connected to the second pilot pipeline connecting the second pilot valve 9b of the means 9 and the first and second pilot pipelines 10a and 10b. The first opening / closing valve 27a and the second opening / closing valve 2 in the two positions having the opened and closed positions.
7b is interposed and the first and second on-off valves 2 thereof are provided.
By-pass line 29a connected in parallel with 7a, 27b,
A first diaphragm 26a and a second diaphragm 26b are interposed in parallel in 29b.

In the above structure, the wiring 28a,
28b to send a mode switching signal to the first on-off valve 2
7a, the second opening / closing valve 27b is in the mode for slowly switching B
When the control lever 8 is switched to the respective positions and the operating lever 8 is operated in the direction of the arrow a in the figure, the pressure oil discharged from the pilot hydraulic pump 5 is supplied from the pipe line 6 to the first pilot valve 9a of the operating means 9 and the first pilot valve 9a. Of the directional control valve 2 through the first pipeline 26a through the pilot pipeline 10a and the bypass pipeline 29a.
The pressure oil is supplied to the first pilot chamber 2a, and the direction switching valve 2 is switched to the left side in the drawing. At this time, the return pressure oil from the second pilot chamber 2b of the directional control valve 2 passes through the second throttle 26b of the bypass conduit 29b and the second pilot conduit 10b, and the second pilot of the operating means 9 is operated. Valve 9
It flows into the tank 4 via b.

Next, when the operating lever 8 is returned to the neutral position from this state, the first pilot chamber 2 of the directional control valve 2
The pressure oil of a passes through the first throttle valve 26a of the bypass line 29a and the first pilot line 10a in order to return the directional control valve 2 to the neutral state, and the first pilot valve 9a of the operating means 9 is operated. And then flows into tank 4. Also the operating lever 8
Is operated in the direction of arrow b in the figure, the direction switching valve 2 operates in the opposite direction to the case of operating in the direction a, and the operating speed is the same as in the slow switching mode.

Further, when a mode switching signal is sent by wires 28a and 28b to switch the first on-off valve 27a and the second on-off valve 27b to the A position which is the normal mode, the operation lever 8 is indicated by an arrow in the figure. When operated in the a direction, the pressure oil discharged from the pilot hydraulic pump 5 is
It is supplied to the first pilot chamber 2a of the directional control valve 2 through the first pilot valve 9a of the operating means 9, the first pilot conduit 10a, and the first opening / closing valve 27a. Switch to the middle left position. At this time, the pressure oil from the second pilot chamber 2b of the direction switching valve 2 passes through the second opening / closing valve 27b, the second pilot pipe line 10b, the second pilot valve 9b of the operating means 9 and reaches the tank 4. Flowing. The pressure oil flowing through the first and second pilot lines 10a and 10b is not limited by the first and second throttles 26a and 26b, and the directional control valve 2 has a response speed corresponding to the operation amount of the operation lever 8. ..

FIGS. 5 and 6 are graphs showing the relationship between the displacement and time of the operating lever 8, the pilot pressure and time, and the displacement and time of the directional control valve 2 in the slow switching mode and the normal mode, respectively. Is shown. In the case of the slow switching mode shown in FIG. 6, the pilot pressure and the time and the displacement of the directional control valve 2 and the time are slower with respect to the displacement of the operation lever 8 than in the case of the normal mode.

[0008]

However, in the above-mentioned conventional structure, when it is desired to suddenly reverse the operating lever from one switching position to the other switching position during work in the slow switching mode, the aperture is always closed. As a result, the switching operation of the directional control valve becomes gradual, and the operation of the actuator is delayed against the operator's intention. This deteriorates workability and sometimes causes a problem in safety.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a hydraulic pilot device capable of improving responsiveness during a sudden reverse operation of an actuator even when working in a slow switching mode. To provide.

[0010]

In order to solve the above-mentioned problems, the features of the structure adopted by the present invention are, as shown in claim 1, a directional control valve for controlling the drive of a hydraulic actuator, and the directional control valve. A first pilot chamber provided on one side and a second pilot chamber provided on the other side; a first pilot valve and a second pilot valve for operating the directional control valve; and the first and second pilot chambers. Tank and pressure oil source respectively connected to the pilot valve of the
First pilot line connecting the second pilot chamber, a second pilot line connecting the second pilot valve and the second pilot chamber, and a first pilot line interposed in the first pilot line First control means for restricting the flow of pressure oil in the pipeline, first flow rate limiting means interposed in parallel with the first control means in the first pilot pipeline, and the second pilot pipeline From the second control means for controlling the flow of the pressure oil in the second pilot conduit, and the second flow restricting means interposed in parallel with the second control means in the second pilot conduit. In the hydraulic pilot device,
First and second flow restricting means for allowing the flow from the first and second pilot valves to the direction switching valve and preventing the flow from the direction switching valve to the first and second pilot valves. The first and second flow rate limiting means and the first and second flow rate limiting means.
Connected to the first and second pilot pipes in parallel with the control means, respectively, between the first flow rate limiting means, the first flow limiting means and the first control means and the first pilot valve. Second control means is connected to the first pilot line of the second flow path via a third pilot line, and the second flow rate limiting means, the second flow limiting means, the second control means, and the second control means. A first control means is connected to the second pilot conduit between the second pilot valve and the second pilot valve via a fourth pilot conduit, and the first and second control means further include a third control means. The configuration is such that the flow of the pressure oil in the first and second pilot pipes is controlled in a direction to be restricted based on the signal from the means.

A directional control valve for controlling the drive of the hydraulic actuator, a first pilot chamber provided on one side of the directional control valve, and a second pilot chamber provided on the other side of the directional control valve. , The first to operate this directional valve
Pilot valve and second pilot valve, a tank and a pressure oil source connected to the first and second pilot valves, respectively, and a first pilot connecting the first pilot valve and the first pilot chamber Pilot-type first opening and closing having a pipeline, a second pilot pipeline connecting the second pilot valve and the second pilot chamber, and an open and closed position interposed in the first pilot pipeline A pilot type first valve provided with a valve, a first flow rate limiting means interposed in a first pilot line in parallel with the first opening / closing valve, and an open and closed position interposed in the second pilot line. In the hydraulic pilot device including the second opening / closing valve and the second flow rate limiting means interposed in the second pilot line in parallel with the second opening / closing valve, the directional switching valve from the first and second pilot valves. Allow the flow to The first and second check valves for blocking the flow from the direction switching valve to the first and second pilot valves are provided as the first and second flow rate limiting means and the first and second opening / closing valves. Are connected in parallel to the first and second pilot pipes, respectively, and are connected to the first flow rate limiting means, the first check valve, and the first check valve.
The pilot chamber of the second on-off valve is connected to the first pilot line between the on-off valve and the first pilot valve via a third pilot line, and the second flow rate limiting means is provided. A second check valve and a pilot chamber of the first on-off valve via a fourth pilot line to the second pilot line between the second on-off valve and the second pilot valve. A first position that connects the first pilot line and the third pilot line, and connects the third pilot line with the first position that connects the pressure oil source and the pilot chamber of the second on-off valve. A first switching valve having a second position that shuts off the pilot chamber of the second on-off valve is provided in the third pilot pipe line, shuts off the fourth pilot pipe line, and supplies a pressure oil source and The first position communicating with the pilot chamber of the first on-off valve and the fourth pilot line communicating with each other And in that the second switching valve and a second position for blocking the pilot chamber of the pressure oil source and the first on-off valve provided in the pilot line of the fourth.

Further, as described in claim 3, a direction switching valve for controlling the drive of the hydraulic actuator, a first pilot chamber provided on one side of the direction switching valve and a second pilot chamber provided on the other side. And a first pilot valve and a second pilot valve for operating the directional control valve, and the first and second pilot valves.
A tank and a pressure oil source respectively connected to the second pilot valve, a first pilot line connecting the first pilot valve and the first pilot chamber, a second pilot valve and a second pilot chamber A pilot-type on-off valve having an open and closed position interposed in the first pilot line, and a second pilot line connecting the first pilot line and the first pilot line in parallel with the first on-off valve. A first flow rate limiting means interposed in the second pilot line, a pilot type second opening / closing valve having an open position and a closed position interposed in the second pilot line, and the second opening / closing in the second pilot line. In a hydraulic pilot device comprising a second flow rate limiting means interposed in parallel with a valve, a flow from the first and second pilot valves to a directional switching valve is permitted, and the directional switching valve from the first and second directional switching valves is allowed. Flow to the pilot valve And a first and a second check valve for blocking the above are respectively connected in parallel to the first and second flow rate limiting means and the first and second opening / closing valves to the first and second pilot pipelines, respectively. Further, a first having two input ports and one output port
A first pilot valve between the first flow restricting means, the first check valve and the first opening / closing valve, and the first pilot valve through an input port on one side of the shuttle valve of the first pilot valve. 1
Of the second on-off valve of the second opening / closing valve is connected to the output port of the second opening / closing valve by the fifth pilot line. A second shuttle valve, which is connected to the pilot chamber and has two input ports and one output port, is provided with an input port on one side of the second shuttle valve by a sixth pilot line.
Check valve and a second pilot line between the second on-off valve and the second pilot valve, and a fourth pilot line in which the input valve on the other side is connected with a switching valve Is connected to the pressure oil source by means of a seventh pilot line, and the output port is connected to the pilot chamber of the first opening / closing valve by means of the switching valve, which connects the pressure oil source to the first and second opening / closing valves. It has a position to obtain and a position to shut off.

Further, a directional control valve for controlling the drive of the hydraulic actuator, a first pilot chamber provided on one side of the directional control valve, and a second pilot chamber provided on the other side of the directional control valve. , The first to operate this directional valve
Pilot valve and second pilot valve, a tank and a pressure oil source connected to the first and second pilot valves, respectively, and a first pilot connecting the first pilot valve and the first pilot chamber Pilot-type first opening and closing having a pipeline, a second pilot pipeline connecting the second pilot valve and the second pilot chamber, and an open and closed position interposed in the first pilot pipeline A pilot type first valve provided with a valve, a first flow rate limiting means interposed in a first pilot line in parallel with the first opening / closing valve, and an open and closed position interposed in the second pilot line. In the hydraulic pilot device including the second opening / closing valve and the second flow rate limiting means interposed in the second pilot line in parallel with the second opening / closing valve, the first opening / closing valve includes the first and second Has a pilot room in front of The second on-off valve is provided with third and fourth pilot chambers, allows the flow from the first and second pilot valves to the directional switching valve, and allows the first and second directional switching valves to flow. Of the first and second check valves for blocking the flow of the second pilot valve to the first and second pilot valves in parallel with the first and second flow rate limiting means and the first and second opening / closing valves. A third pilot in the first pilot line between the first flow restricting means, the first check valve and the first on-off valve, and the first pilot valve, the third pilot being connected to the first line, respectively. A third pilot chamber of the second opening / closing valve is connected via a pipe, and the second flow rate limiting means, the second check valve, and the second opening / closing valve and the second pilot valve are connected to each other. The first pilot chamber of the first on-off valve is connected to the second pilot line of the above through a fourth pilot line of The second and fourth pilot chambers of the first and second on-off valves are connected to the pressure oil source by a fifth pilot pipe line with a switching valve interposed, and the switching valve is connected to the pressure oil source and the second , The fourth pilot chamber is provided with a position for communicating with and a position for shutting off. Further, as shown in claim 5, a drive device for driving the opening / closing valve by an electric signal is attached to each of the second and fourth pilot chambers of the opening / closing valve having two pilot chambers on one side shown in claim 4. Especially.

[0014]

Since the present invention is configured as described above,
In Claim 1, when the third control means is switched to a state in which the first and second control means operate in accordance with the operating states of the first and second pilot valves and the first pilot valve is operated, the pressure is reduced. The pressure oil from the oil source is the first pilot line, the first
And is supplied to the first pilot chamber of the directional control valve. At this time, the pressure oil is also supplied to the third pilot line, the second control means controls the pressure oil in the second pilot line to communicate with each other, and the pressure oil from the second pilot chamber of the directional control valve is supplied. When the pressure oil returns to the tank through the second control means, the directional control valve is switched and the hydraulic actuator is driven. When the first pilot valve is returned to the neutral state from this state, the pressure oil from the first pilot chamber of the directional control valve flows into the tank via the first flow rate limiting means, so that the directional control valve is loosened. Return to neutral position. Next, when the first pilot valve is returned to the neutral state and the second pilot valve is suddenly operated (when the reverse lever is operated) from the state in which the first pilot valve is operated, the second pilot line The pressure oil output to the second pilot chamber of the directional control valve is supplied to the second pilot chamber of the directional control valve via the second flow restricting means, and is also supplied to the fourth pilot pipe line. The pressure oil from the first pilot line is controlled to communicate, and the pressure oil from the first pilot chamber of the directional control valve flows into the tank without restriction, so that the directional control valve rapidly moves to the reverse position. Can be switched. Thus, the third control means controls the first and second control means to operate in accordance with the operating states of the first and second pilot valves, so that the hydraulic actuator suddenly operates in reverse. .. The hydraulic actuator operates the first and second pilot valves by controlling the first and second control means so that the third control means always connects the first and second pilot lines. Perform an operation according to the amount.

Further, in claim 2, when the first and second switching valves are switched to the second position and the first pilot valve is operated, the pressure oil from the pressure oil source is supplied to the first pilot line, the first pilot line.
And is supplied to the first pilot chamber of the directional control valve. At this time, pressure oil is also supplied to the third pilot line, the second opening / closing valve is switched to the open position, and the pressure oil from the second pilot chamber of the directional control valve passes through the second opening / closing valve. The directional control valve is switched and the hydraulic actuator is driven by returning to the tank. When the first pilot valve is returned to the neutral state from this state, the pressure oil from the first pilot chamber of the directional control valve flows into the tank via the first flow rate limiting means, so that the directional control valve is loosened. Return to neutral position. Next, when the first pilot valve is returned to the neutral state and the second pilot valve is suddenly operated (when the reverse lever is operated) from the state in which the first pilot valve is operated, the second pilot line The pressure oil output to
It is supplied to the second pilot chamber of the directional control valve via the second check valve and also to the fourth pilot line, and the first opening / closing valve is switched to the open position to switch the direction. Pressure oil from the first pilot chamber of the valve flows through the first on-off valve to the tank, thereby rapidly switching the directional control valve to the reverse position. As a result, the hydraulic actuator suddenly reverses at the second position of the first and second switching valves. Further, when the first and second switching valves are switched to the first position, the pressure oil discharged from the pressure oil source is always supplied to the pilot chambers of the first and second opening / closing valves. ,
The on-off valves hold the first and second pilot lines in the open position, and the hydraulic actuators operate according to the operation amounts of the first and second pilot valves.

Further, in claim 3, when the switching valve is switched to a position where the fourth pilot line is shut off and the first pilot valve is operated, the pressure oil from the pressure oil source is supplied to the first pilot line, the first pilot line. And is supplied to the first pilot chamber of the directional control valve. At this time, the pressure oil is also supplied to the third pilot pipe line, and the pressure oil is supplied to the first shuttle valve and the fifth shuttle valve.
Is supplied to the pilot chamber of the second opening / closing valve via the pilot pipe of the second opening / closing valve, and the second opening / closing valve is switched to the open position,
Pressure oil from the second pilot chamber of the directional control valve returns to the tank through the second on-off valve. Therefore, the directional control valve is switched and the hydraulic actuator is driven. When the first pilot valve is returned to the neutral state from this state, the pressure oil from the first pilot chamber of the directional control valve flows into the tank via the first flow rate limiting means, so that the directional control valve is loosened. Return to neutral position. Next, when the first pilot valve is returned to the neutral state and the second pilot valve is suddenly operated (when the reverse lever is operated) from the state in which the first pilot valve is operated, the second pilot line The pressure oil output to
It is supplied to the second pilot chamber of the direction switching valve via the second check valve and also to the sixth pilot line, and is supplied via the second shuttle valve and the seventh pilot line. , The pilot chamber of the first on-off valve. As a result, the first opening / closing valve is switched to the open position, and the pressure oil from the first pilot chamber of the directional switching valve flows into the tank through the first opening / closing valve, so that the directional switching valve rapidly moves. Switch to the reverse position. As a result, the switching valve has a fourth
At the position where the pilot pipe line is cut off, the hydraulic actuator suddenly operates in reverse. When the switching valve is switched to a position communicating with the fourth pilot line, the hydraulic actuator operates according to the operation amounts of the first and second pilot valves.

Further, in claim 4, when the switching valve is switched to a position where the fifth pilot line is shut off and the first pilot valve is operated, the pressure oil from the pressure oil source is supplied to the first pilot line and the first pilot line. And is supplied to the first pilot chamber of the directional control valve. At this time, the pressure oil is also supplied to the third pilot pipe line to supply the pressure oil to the third pilot chamber of the second opening / closing valve, and the second opening / closing valve is switched to the open position, so that the direction switching valve is opened. By returning the pressure oil from the second pilot chamber to the tank through the second opening / closing valve, the direction switching valve is switched and the hydraulic actuator is driven. When the first pilot valve is returned to the neutral state from this state, the pressure oil from the first pilot chamber of the directional control valve flows into the tank via the first flow rate limiting means, so that the directional control valve is loosened. Return to neutral position. Next, when the first pilot valve is returned to the neutral state and the second pilot valve is suddenly operated (when the reverse lever is operated) from the state in which the first pilot valve is operated, the second pilot line The pressure oil output to the second pilot chamber of the directional control valve is supplied to the second pilot chamber of the directional control valve as well as to the fourth pilot line of the first opening / closing valve. The pressure oil is supplied to the first pilot chamber, the first opening / closing valve is switched to the open position, and the pressure oil from the first pilot chamber of the direction switching valve flows to the tank through the first opening / closing valve. Thereby, the directional control valve is rapidly switched to the reverse position. This allows
At the position where the switching valve closes the fifth pilot line, the hydraulic actuator suddenly operates in reverse. Further, when the switching valve is switched to a position where the second and fourth pilot chambers communicate with the pressure oil source, the pressure oil discharged from the pressure oil source becomes the fifth pressure oil.
Through the pilot line of the first and second opening / closing valves
No. 4 pilot chamber is constantly supplied, and the open / close valve is held in the open position, so that the hydraulic actuator operates according to the operation amounts of the first and second pilot valves.

Further, according to the present invention, the opening / closing valve is opened by sending an electric signal for switching the opening / closing valve to a drive device provided in each of the second and fourth pilot chambers of the opening / closing valve having two pilot chambers. A state in which the position is maintained or a state in which the first and second pilot valves are switched can be selected according to the operation.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the hydraulic pilot device of the present invention will be described below with reference to FIG. The same components as those shown in FIG. 4 described above are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 1, 15a and 15b allow the flow of pressure oil from the operating means 9 to the directional switching valve 2 and prevent the flow of pressure oil from the directional switching valve 2 to the operating means 9. Second pilot conduits 10a, 10b
And the first and second check valves interposed in the. First and second
In the pilot lines 10a and 10b of the first check valve 1
5a and the second check valve 15b in parallel with the bypass line 33
a, 34a, 33b, 34b are connected. In the bypass conduits 33a and 33b, the first and second throttles 14a and 14b as flow rate restricting means, the bypass conduit 34a,
34b includes two first and second on-off valves 16a and 16b having an open position and a closed position which are operated by pilot pressure.
Are intervening. 17a and 17b are pilot chambers provided in the first and second on-off valves 16a and 16b,
Reference numeral 12a denotes a pilot chamber 17b of the second opening / closing valve 16b.
For supplying pressure oil to the operating means 9 and the bypass line 3
A third pilot pipe line 12b branched from the first pilot pipe line 10a between the first and second open / close valves 16a and 3a and 34a is for supplying pressure oil to the pilot chamber 17a of the first opening / closing valve 16a. , Operating means 9 and bypass lines 33b, 3
4b, the fourth pilot conduits 19a, 19b branching from the second pilot conduit 10b between
A second position c that connects the second pilot conduits 10a and 10b to the pilot chambers 17a and 17b of the first and second opening / closing valves 16a and 16b, respectively, and the first and second pilot conduits 10a and 10a. 10b and the first and second on-off valves 16a,
The communication with the pilot chambers 17a, 17b of 16b is cut off, and the pilot chambers 17a, 17b of the first and second on-off valves 16a, 16b are connected to the first position d for communicating the discharge side of the pilot hydraulic pump 5. A switching valve which is provided and is interposed in the third and fourth pilot lines 12a and 12b, and 20 is a wire for transmitting a mode switching signal to the first and second switching valves 19a and 19b.

In the hydraulic pilot device configured as described above, a case will be described in which the first and second switching valves 19a and 19b are switched to the second position c which is the slow switching mode by the mode switching signal. .. Operating lever 8
Is operated in the direction of arrow a in the figure, the pressure oil discharged from the pilot hydraulic pump 5 is supplied to the first pilot conduit 10a by the operating means 9. The pressure oil supplied to the first pilot conduit 10a passes through the first check valve 15a and is supplied to the first pilot chamber 2a of the direction switching valve 2. Further, in this case, the pressure oil in the first pilot conduit 10a passes through the third pilot conduit 12a, the pressure is transmitted to the pilot chamber 17b of the second opening / closing valve 16b, and the second opening / closing valve 16b is closed. The pressure oil returned from the second pilot chamber 2b of the directional control valve 2 is switched from the position to the open position, and the pressure oil returned from the second opening / closing valve 16b to the second pilot line 10b and the second pilot valve of the operating means 9 is operated. It flows into the tank 4 via 9b. Therefore, the directional control valve 2 is switched to the left position in the figure. When the operation lever 8 is returned to the neutral position from this switching state, the direction switching valve 2 by the neutral return spring of the direction switching valve 2
By the action of returning to the neutral position of the directional control valve 2
The pressure oil in the first pilot chamber 2a of the
Returning to the tank 4 via the first pilot valve 9a of the operating means 9 through a. The flow of pressure oil is restricted by the first throttle 14a, the operation speed of the directional control valve 2 is slow, and even when the operating lever 8 is suddenly returned to the neutral position, the operation of the cylinder 3, which is the actuator, at the time of stop is moderate. Controlled. Further, when the operation lever 8 is suddenly reversed from the position in the direction a to the position in the direction b beyond the neutral position, the pressure oil discharged from the pilot hydraulic pump 5 is supplied to the second pilot conduit 10.
b through the check valve 15b, and is supplied to the second pilot chamber 2b of the direction switching valve 2. At this time, the pressure oil flowing through the second pilot conduit 10b is
It also flows to b, is supplied to the pilot chamber 17a of the first opening / closing valve 16a via the second switching valve 19b, and the first opening / closing valve 16a is switched to the open position. As a result, the pressure oil in the first pilot chamber 2a of the direction switching valve 2 returns to the tank 4 through the first opening / closing valve 16a, and the direction switching valve 2 switches to the right position in the figure. Therefore, the pressure oil returning from the first pilot chamber 2a is not limited by the first throttle 14a.

Next, the operation when the first and second switching valves 19a and 19b are switched to the first position d which is the normal mode will be described. First and second switching valves 19a, 19b
Is switched to the first position d, the pressure oil discharged from the pilot hydraulic pump 5 is always kept in the first and second opening / closing valves 16
The first and second on-off valves 16a and 16b act on the pilot chambers 17a and 17b of a and 16b, and hold the state in which they are switched to the position where the operation means 9 and the direction switching valve 2 are communicated with each other. Is the first and second throttles 1 as flow rate limiting means
It is not restricted by 5a and 15b.

According to the first embodiment, when the first and second switching valves 19a and 19b are switched to the second position c,
When the operating lever 8 is returned from the respective operating directions a and b to the neutral position, the first and second pilot conduits 10a and 10b
Since the pressure oil flowing through is restricted by the first and second throttles 14a and 14b, the impact when the cylinder 3 which is the actuator is stopped is mitigated, but the operation lever 8 is operated in a sudden reverse operation beyond the neutral position. In this case, the pressure oil flowing through the first and second pilot conduits 10a and 10b is the first and second throttle 1
Since it is not restricted by 4a and 14b, the response to the operation lever 8 can be improved. Further, when the first and second switching valves 19a and 19b are switched to the first position d, the pressure oil flowing through the first and second pilot conduits 10a and 10b is irrespective of the movement of the operation lever 8. Since the first and second throttles 14a and 14b are not limited, the directional control valve 2 follows the operation lever 8 and the responsiveness corresponding to the operation lever 8 is improved.

Next, a second embodiment will be described with reference to FIG. Here, the components similar to those in the first embodiment include:
The same reference numerals are given and the description thereof is omitted.

In the first embodiment, the first and second on-off valves 16
a and 16b control the pressure oil discharged from the pilot hydraulic pump 5 and supplied to the pilot chambers 17a and 17b by the first and second switching valves 19a and 19b.
Instead, as shown in FIG. 2, the pilot chamber 17a of the first opening / closing valve 16a includes a second shuttle valve 37 having two input ports and one output port, and a seventh pilot line. 39, the second shuttle valve 37 has an input port on one side connected to the operating means 9 by the sixth pilot line 35b and the second pilot line 10b between the bypass lines 33b and 34b. The input port on the other side is connected to the pilot hydraulic pump 5 by a fourth pilot line 40 in which a switching valve 41 is interposed. In addition, the pilot chamber 17b of the second on-off valve 16b
Is connected by a fifth pilot line 38 to an output port of a first shuttle valve 36 having two input ports and one output port, the input port on one side of the first shuttle valve 36 being a first port. The operation means 9 by the pilot line 35a of 3
Is connected to the first pilot conduit 10a between the bypass conduits 33a and 34a, and the input port on the other side is connected to the pilot hydraulic pump 5 by the fourth pilot conduit 40 in which the switching valve 41 is interposed. It is connected to the.

Here, the switching valve 41 has a position e for connecting the pilot hydraulic pump 5 to the first and second shuttle valves 36 and 37, and the pilot hydraulic pump 5 to the first and second shuttle valves 36 and 37. 37 and a position f for connecting the first and second shuttle valves 36, 37 and the tank 4 to each other are provided, and the structure is such that switching is performed by a signal transmitted by the wiring 42.

In the second embodiment configured as described above, the case where the switching valve 41 is switched to the position f which is the slow switching mode by the mode switching signal will be described. When the operating lever 8 is operated in the direction of arrow a in the figure,
The pressure oil discharged from the pilot hydraulic pump 5 is supplied to the first pilot conduit 10a by the operating means 9. The pressure oil supplied to the first pilot conduit 10a is
It is supplied to the first pilot chamber 2a of the directional control valve 2 through the first check valve 15a. Further, in this case, the pressure oil in the first pilot conduit 10a passes through the third pilot conduit 35a and is supplied to the input port on one side of the first shuttle valve 36. Since the input port on the other side of the first shuttle valve 36 is connected to the tank 4, the pressure oil in the third pilot line 35a passes through the first shuttle valve 36 and the fifth pilot line 38. Pilot chamber 17b of the second on-off valve 16b
The pressure is transmitted to the second open / close valve 16b, and the second open / close valve 16b switches from the closed position to the open position. As a result, the return pressure oil of the second pilot chamber 2b of the directional control valve 2 passes from the second opening / closing valve 16b to the tank 4 through the second pilot line 10b and the second pilot valve 9b of the operating means 9. The directional control valve 2 is switched to the left side position in the figure since it returns to. When the operation lever 8 is returned to the neutral position from this switching state, the neutral return spring of the directional switching valve 2 tries to return to the neutral position of the directional switching valve 2, whereby the first pilot chamber 2a of the directional switching valve 2 is moved.
The pressure oil inside passes through the first throttle 14a, returns to the tank 4 via the first pilot valve 9a of the operating means 9. The flow of pressure oil is restricted by the first throttle 14a, and the directional control valve 2
Is slow, and even when the operating lever 8 is suddenly returned to the neutral position, the operation of the cylinder 3, which is an actuator, at the time of stop is controlled gently. Further, when the operating lever 8 is suddenly reversed from the position in the a direction to the position in the b direction beyond the neutral position, the pressure oil discharged from the pilot hydraulic pump 5 is supplied to the second pilot line 10b and the check valve 15b. And is supplied to the second pilot chamber 2b of the directional control valve 2. At this time, when the pressure oil flowing through the second pilot conduit 10b is supplied to the input port on one side of the second shuttle valve 37 via the sixth pilot conduit 35b, the second shuttle valve Since 37 has an input port on the other side connected to the tank 4 via the fourth pilot conduit 40, it moves to the left side in the drawing due to the pressure oil, and passes through the seventh pilot conduit 39 to The first opening / closing valve 16a is supplied to the pilot chamber 17a of the first opening / closing valve 16a, and the first opening / closing valve 16a is switched to the open position. As a result, the pressure oil in the first pilot chamber 2a of the direction switching valve 2 returns to the tank 4 through the first opening / closing valve 16a, and the direction switching valve 2 switches to the right position in the figure. Therefore, the pressure oil returned from the first pilot chamber 2a is the first throttle 14a.
Not subject to the restrictions of.

Next, the switching valve 41 is set to the position e in the normal mode.
The operation when switched to will be described. Switching valve 41
Is switched to the position e, the pressure oil discharged from the pilot hydraulic pump 5 and having the maximum pressure set by the relief valve 7 passes through the fourth pilot pipe 40, and the first and second shuttle valves 36, When supplied to the input port on the other side of 37, the first and second shuttle valves 36, 37 cause the fourth pilot line 40 and the fifth and seventh pilot lines 38,
39 to communicate with each other, and the pressure oil is supplied to the pilot chambers 17a and 17b of the first and second opening / closing valves 16a and 16b so that the first and second opening / closing valves 16a and 16b are directed to the operating means 9. The state of being switched to a position in which the switching valve 2 is in communication is maintained. Therefore, the flow of the pressure oil is not restricted by the first and second throttles 15a and 15b as the flow rate restricting means.

As described above, as an effect of the second embodiment,
In addition to the effects of the first embodiment, in the first embodiment,
Two switching valves were required to control the second on-off valves 16a and 16b, but in this embodiment, one switching valve 41 and two shuttle valves are used. Can be done easily.

Next, a third embodiment is shown in FIG. The same components as those of the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the changeover valve 41 is changed over so that the pressure oil is supplied via the first and second shuttle valves 36 and 37.
The first and second on-off valves 16a and 16b were supplied to the pilot chambers 17a and 17b to switch between the slow switching mode and the normal mode. Instead,
First and second intervening bypass lines 34a, 34b
The on-off valves 16a and 16b of the first, second and third and fourth pilot chambers 43a, 43b and 44a,
44b is provided as the first and second on-off valves 43 and 44 which are switched by two pilot pressures, and the first and third pilot chambers 43a and 44a are respectively the fourth and third pilot conduits 12b and 12a. And the second and fourth pilot chambers 43b and 44b are connected to the fifth pilot line 4
0 is connected to the switching valve 41.

In the third embodiment configured as described above, a case will be described in which the switching valve 41 is switched to the position f which is the slow switching mode by the mode switching signal. When the operating lever 8 is operated in the direction of arrow a in the figure, the pressure oil discharged from the pilot hydraulic pump 5 is supplied to the first pilot conduit 10a by the operating means 9.
The pressure oil supplied to the first pilot conduit 10a is
Is supplied to the first pilot chamber 2a of the direction switching valve 2 through the check valve 15a. Further, in this case, the pressure oil of the first pilot conduit 10a is transmitted to the third pilot chamber 44a of the second opening / closing valve 44 through the third pilot conduit 12a, and the second opening / closing valve is opened. 44 switches from the closed position to the open position. Therefore, the return pressure oil of the second pilot chamber 2b of the direction switching valve 2 is supplied from the second opening / closing valve 44 to the second pilot conduit 10b and the second pilot valve 9 of the operating means 9.
It flows into the tank 4 via b. Therefore, the directional control valve 2 is switched to the left position in the figure. When the operation lever 8 is returned to the neutral position from this switching state, the neutral return spring of the directional switching valve 2 tries to return to the neutral position of the directional switching valve 2 so that the inside of the first pilot chamber 2a of the directional switching valve 2 is closed. The pressure oil passes through the first throttle 14a, returns to the tank 4 via the first pilot valve 9a of the operating means 2. First diaphragm 14
By a, the flow of pressure oil is restricted, the operation speed of the direction switching valve 2 is slow, and even when the operating lever 8 is suddenly returned to the neutral position, the operation of the cylinder 3 which is the actuator at the time of stop is gently controlled. Further, when the operating lever 8 is suddenly reversed from the position in the a direction to the position in the b direction beyond the neutral position, the pressure oil discharged from the pilot hydraulic pump 5 is supplied to the second pilot line 10b and the check valve 15b. And is supplied to the second pilot chamber 2b of the directional control valve 2. At this time,
The pressure oil flowing through the second pilot pipe line 10b also flows through the fourth pilot pipe line 12b and flows into the first pilot chamber 43a of the first on-off valve 43 provided in the first pilot pipe line 10a. When supplied, the first on-off valve 43 switches to the open position. As a result, the pressure oil in the first pilot chamber 2a of the direction switching valve 2 passes through the first opening / closing valve 43 and the tank 4
Then, the directional control valve 2 is switched to the right position in the figure. Therefore, the pressure oil returning from the first pilot chamber 2a is not limited by the first throttle 14a.

Next, the switching valve 41 is moved to the position e in the normal mode.
The operation when switched to will be described. Switching valve 41
When switching to a position e in which the first hydraulic valve 5 communicates with the second hydraulic valve, the hydraulic fluid discharged from the pilot hydraulic pump 5 is always sent through the fifth pilot conduit 40 to the second and fourth opening / closing valves 43 and 44. It acts on the pilot chambers 43b and 44b, and the first and second
Since the on-off valves 43 and 44 of FIG. 4 maintain the state in which they are switched to the position where the operating means 9 and the directional control valve 3 are communicated with each other, the pressure oil has the first and second throttles 14a and 14b as the flow rate limiting means.
Not subject to the restrictions of.

As described above, as an effect of the third embodiment,
In addition to the first and second effects, it is sufficient to use only one switching valve 41 as a means for switching modes, and the number of hydraulic devices can be increased by changing the switching valve to a switching valve having two pilot chambers. Since the number is reduced, the configuration can be simplified.

Further, in the third embodiment, the first and second on-off valves 43 and 44 to which the pressure oil is supplied are used for the first and second pilot chambers and the third and fourth pilot chambers. However, in the first and third pilot chambers 43a and 44a, the third and fourth pilot chambers are provided.
It is assumed that the pressure oil is supplied through the pilot pipe lines 12a and 12b of the above, and the second and fourth pilot chambers are replaced by that.
The switching valve 41 can be omitted by operating the first and second on-off valves 43 and 44 directly by the mode switching signal with a structure in which a drive device that can be electrically driven is attached.

The first switching valve 19a, the second switching valve 19b, and the switching valve 4 in the first, second, and third embodiments described above.
Although 1 is electrically controlled, the same effect can be obtained by mechanically controlling with a lever or the like.

Further, in the above-mentioned first, second and third embodiments,
When the first and second switching valves 19a and 19b are switched to the first position d or the switching valve 41 to the position e, respectively, the first and second switching valves 16a and 16b or the switching valves 43 and 44 are switched. Although the pressure oil from the pilot hydraulic pump 5 was supplied to the pilot chamber of No. 3, another pressure oil source may be used.

[0037]

As described above, according to the hydraulic pilot device of the present invention, the working mode can be selected between the slow switching mode and the normal mode according to the work, and the shock when the actuator is stopped is reduced in the slow switching mode. The workability can be improved by improving the responsiveness of the actuator during the sudden reverse operation.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a hydraulic pilot device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a hydraulic pilot device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a hydraulic pilot device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a hydraulic pilot device according to the related art.

FIG. 5 is a time chart explaining the movement in the normal mode shown in FIG.

FIG. 6 is a time chart for explaining the movement in the slow switching mode shown in FIG.

[Explanation of symbols]

 2 Direction switching valve 2a First pilot chamber 2b Second pilot chamber 4 Tank 5 Pressure oil source 9a First pilot valve 9b Second pilot valve 10a First pilot line 10b Second pilot line 12a Second 3 pilot line 12b 4th pilot line 14a 1st flow restricting means 14b 2nd flow restricting means 15a 1st flow restricting means 15b 2nd flow controlling means 16a 1st controlling means 16b 2nd Control means 19a Third control means 19b Third control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimio Katsuki, 650 Kandachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory

Claims (5)

[Claims] 1. A directional control valve for controlling the drive of a hydraulic actuator, a first pilot chamber provided on one side of the directional control valve and a second pilot chamber provided on the other side, and this directional control valve. A first pilot valve and a second pilot valve to be operated, a tank and a pressure oil source respectively connected to the first and second pilot valves, a first pilot valve and a first pilot chamber are connected. A first pilot line, a second pilot line connecting the second pilot valve and the second pilot chamber, a pressure oil of the first pilot line interposed in the first pilot line, A first control means for regulating the flow, a first flow rate limiting means interposed in the first pilot conduit in parallel with the first control means, and a second flow restrictor interposed in the second pilot conduit. Flow of pressure oil in pilot line In a hydraulic pilot device comprising a second control means for restricting the flow rate and a second flow rate limiting means interposed in a second pilot line in parallel with the second control means. The first and second flow restricting means for allowing the flow from the valve to the directional control valve and blocking the flow from the directional control valve to the first and second pilot valves. The first flow rate limiting means, the first flow limiting means, and the first control means are respectively connected to the first and second pilot pipelines in parallel with the flow rate limiting means and the first and second control means. Second control means is connected to the first pilot pipe between the first pilot valve and the second flow restricting means, and the second flow restricting means. Means and second control means and said second pilot valve between said The first control means is connected to the second pilot line via the fourth pilot line, and the first and second control means further include first and second control means based on a signal from the third control means. A hydraulic pilot device, characterized in that it is configured to control the flow of pressure oil in the second pilot line in a direction in which it is restricted. 2. A directional control valve for controlling the drive of a hydraulic actuator, a first pilot chamber provided on one side of the directional control valve and a second pilot chamber provided on the other side, and the directional control valve. A first pilot valve and a second pilot valve to be operated, a tank and a pressure oil source respectively connected to the first and second pilot valves, a first pilot valve and a first pilot chamber are connected. A pilot-type pilot line having a first pilot line, a second pilot line connecting the second pilot valve and the second pilot chamber, and an open and closed position interposed in the first pilot line. A first opening / closing valve, a first flow rate limiting device interposed in a first pilot line in parallel with the first opening / closing valve, and an open and closed position interposed in the second pilot line. Pilot type second opening and closing In a hydraulic pilot device comprising a valve and a second flow rate limiting means interposed in a second pilot line in parallel with the second opening / closing valve, the first and second pilot valves are changed to a direction switching valve. The first and second check valves that permit the flow and prevent the flow from the directional switching valve to the first and second pilot valves are provided with the first and second flow rate limiting means and the first and second flow limiting means. First and second parallel to the second on-off valve
Of the first flow restricting means, the first check valve and the first opening / closing valve, and the third pilot line between the first pilot line and the first pilot line. Is connected to the pilot chamber of the second on-off valve, and the second flow rate restricting means, the second check valve, and the second on-off valve and the second pilot valve are connected to each other. The second
To the pilot line of the first through the fourth pilot line
Connecting the pilot chamber of the on-off valve, shutting off the third pilot line, and communicating the third position with the first position for connecting the pressure oil source and the pilot chamber of the second on-off valve. And a first switching valve having a second position for shutting off the pressure oil source and the pilot chamber of the second on-off valve is provided in the third pilot pipe line, and shuts off the fourth pilot pipe line. And also connects the first position, which connects the pressure oil source and the pilot chamber of the first on-off valve, with the fourth pilot line, and shuts off the pressure oil source and the pilot chamber of the first on-off valve. And a second switching valve having a second position which is provided on the fourth pilot line. 3. A directional control valve for controlling the drive of a hydraulic actuator, a first pilot chamber provided on one side of the directional control valve and a second pilot chamber provided on the other side, and this directional control valve. A first pilot valve and a second pilot valve to be operated, a tank and a pressure oil source respectively connected to the first and second pilot valves, a first pilot valve and a first pilot chamber are connected. A pilot-type pilot line having a first pilot line, a second pilot line connecting the second pilot valve and the second pilot chamber, and an open and closed position interposed in the first pilot line. A first opening / closing valve, a first flow rate limiting device interposed in a first pilot line in parallel with the first opening / closing valve, and an open and closed position interposed in the second pilot line. Pilot type second opening and closing In a hydraulic pilot device comprising a valve and a second flow rate limiting means interposed in a second pilot line in parallel with the second opening / closing valve, the first and second pilot valves are changed to a direction switching valve. The first and second check valves that permit the flow and prevent the flow from the directional switching valve to the first and second pilot valves are provided with the first and second flow rate limiting means and the first and second flow limiting means. First and second parallel to the second on-off valve
Of the first shuttle valve having two input ports and one output port, and an input port on one side of the first shuttle valve having a second input port and an output port by means of a third pilot line. 1 check valve and 1st on-off valve and said 1st
Connected to the first pilot line between the pilot valve and the other side, the other side input port is connected to the pressure oil source by the fourth pilot line in which the switching valve is interposed, and the output port is connected to the fifth line. A pilot line is connected to the pilot chamber of the second on-off valve, and one input port on one side of a second shuttle valve having two input ports and one output port is connected to the second pilot valve by a sixth pilot line. The flow rate limiting means, the second check valve, the second opening / closing valve and the second pilot valve between the second pilot valve and the second pilot line are connected to each other, and the other side of the input port is provided with a switching valve. The fourth pilot line connects to the pressure oil source, the output port connects to the pilot chamber of the first on-off valve by the seventh pilot line, and the switching valve connects the pressure oil source to the first and second And a position where the first and second on-off valves can communicate with each other via the shuttle valve of Hydraulic pilot device characterized by comprising a position and get. 4. A directional control valve for controlling the drive of a hydraulic actuator, a first pilot chamber provided on one side of the directional control valve and a second pilot chamber provided on the other side, and this directional control valve. A first pilot valve and a second pilot valve to be operated, a tank and a pressure oil source connected to the first and second pilot valves, respectively, and a first pilot valve and a first pilot chamber are connected. A first pilot line, a second pilot line connecting the second pilot valve and the second pilot chamber, and a pilot chamber having open and closed positions interposed in the first pilot line. A first opening / closing valve, a first flow rate limiting device interposed in a first pilot line in parallel with the first opening / closing valve, and an open and closed position interposed in the second pilot line. Pilot type second opening and closing In a hydraulic pilot device comprising a valve and a second flow rate limiting device interposed in a second pilot line in parallel with the second opening / closing valve, the first opening / closing valve includes first and second pilot chambers. The second opening / closing valve is provided with the third and fourth pilot chambers, allows the flow from the first and second pilot valves to the directional switching valve, and controls the directional switching valve. From first, second
Of the first and second check valves for blocking the flow of the gas to the pilot valve in parallel with the first and second flow rate limiting means and the first and second opening / closing valves. A third pilot in the first pilot line between the first flow restricting means, the first check valve and the first on-off valve, and the first pilot valve, the third pilot being connected to the first line, respectively. The third pilot chamber of the third on-off valve is connected via a pipe, and the second
Flow restricting means, a second check valve, a second opening / closing valve, and a second opening / closing valve between the second pilot valve and the second pilot line via a fourth pilot line. The first and second pilot chambers of the first and second on-off valves and the pressure oil source are connected by a fifth pilot line through a switching valve, The switching valve is
A hydraulic pilot device, comprising: a position for connecting a pressure oil source to the second and fourth pilot chambers and a position for disconnecting the same. 5. The hydraulic pilot device according to claim 4, wherein a drive device for driving the opening / closing valve by an electric signal is attached to the second and fourth pilot chambers of the opening / closing valve.