JPH10220412A - Hydraulic pressure control circuit for cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To circulate a hydraulic fluid as a whole and properly. SOLUTION: Regarding the hydraulic control circuit 10 of a double acting cylinder device 11, the first and the second check valves 44 and 45 for interrupting a flow from the cylinder device 11 to a selector valve 34, as well as the first and the second tank return oil passages 46 and 47 for returning pressure oil to a tank 20 are connected to the first oil passage 40 and the second oil passage 41. Also, the first tank return oil passage 46 is provided with the first operated check valve 48, and the second tank oil return oil passage 47 with the second operated check valve 49. When a piston 18 is pushed toward the second chamber 17, due to pressure oil in the first chamber 16, pressure oil in the second chamber 17 is discharged to the second oil passage 41. In this case, the second operated check valve 49 allows a flow from the cylinder device 11 to the tank 20, due to the pressure of the first oil passage 40. Thus, the pressure oil discharged to the second oil passage 41 is returned to the tank 20 communicated to the second tank return oil passage 47 and the second operated check valve 49. According to this construction, the pressure oil discharged from the cylinder device 11 is all returned to the tank 20 and passes a filter 37, thereby removing abrasion powder or the like mixed with the pressure oil at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control circuit for a cylinder device, and more particularly to a hydraulic device for reciprocating a double-acting hydraulic cylinder device by a hydraulic pump. The present invention relates to a device that is effective when used in a tailgate opening / closing cylinder device or the like.

[0002]

2. Description of the Related Art For example, a double-acting hydraulic cylinder device (hereinafter referred to as a cylinder device) is used in a cylinder device for a cab tilt, a cylinder device for opening and closing a wing, and a cylinder device for opening and closing a tailgate. )) Is configured as follows. That is, the hydraulic control circuit of the conventional cylinder device of this type includes the first port and the second port.
A cylinder device in which a cylinder chamber having a port is partitioned into a first chamber and a second chamber by a piston, and a piston rod is inserted through the second chamber; and a first oil connected to the first port and the second port, respectively. A pump and a directional switching valve interposed in the passage and the second oil passage, a tank connected to a tank port of the directional switching valve via a tank oil passage, and a tank connected to a tank-side end of the tank oil passage. And an installed filter.

For example, hydraulic oil compressed by a pump is
When supplied to the first chamber of the cylinder device through the oil passage and the piston is pushed toward the second chamber, hydraulic oil is discharged from the second chamber, and the hydraulic oil discharged from the second chamber is passed through the second oil passage. It is guided directly to the suction side of the pump. By directly guiding the hydraulic oil discharged from the cylinder device to the suction side of the pump in this way, the pump can secure hydraulic oil at a predetermined pressure on the suction side.

[0004]

In the hydraulic control circuit of the cylinder device described above, since the hydraulic oil discharged from the cylinder device is guided to the suction side of the pump, bubbles are generated in the hydraulic oil in the cylinder device and the oil passage. When mixed, the air bubbles are sucked into the pump, and the performance of the pump is reduced, or abnormal noise is generated by abnormal vibration of the pump. Also,
Since a situation occurs in which some hydraulic oil moves between the cylinder device and the pump, wear powder and foreign substances mixed in the hydraulic oil due to long-term use of the hydraulic control circuit of the cylinder device will not return to the tank. A situation occurs in which the filter is not removed. If abrasion powder or foreign matter remains in the hydraulic oil, the sliding parts of the pump may be abnormally worn or seized, or may be caught in the switching valve, resulting in abnormal operation of the valve or abnormal hydraulic pressure. I do.

An object of the present invention is to provide a hydraulic control circuit for a cylinder device that can circulate hydraulic oil entirely and reliably.

[0006]

According to the present invention, there is provided a hydraulic control circuit for a cylinder device, wherein a cylinder chamber having a first port and a second port is partitioned into a first chamber and a second chamber by a piston, and a piston rod is provided in a second chamber. A cylinder device inserted through the chamber, a forward / reverse rotating pump provided in a first oil passage and a second oil passage connected to the first port and the second port, respectively, and a tank provided in the pump. In a hydraulic control circuit of a cylinder device including a tank connected via an oil passage and a filter provided at a tank side end of the tank oil passage, the first oil passage and the second oil A first check valve and a second check valve configured to prevent flow from the cylinder device side to the pump side are interposed in the passage, respectively, and the first oil passage is provided. A first tank return oil path and a second tank return oil path for returning hydraulic oil to the tank are connected to the second oil path, respectively, and a first operating check valve is provided in the first tank return oil path. This first operating check valve is connected to a first pilot passage for introducing the pressure of the second check valve on the pump side in the second oil passage, and is normally connected to the tank device from the cylinder device side. To block the distribution to the
When pressure is introduced from the pilot passage, the passage from the cylinder device side to the tank side is configured to be allowed, and a second operation check valve is provided in the second tank return oil passage. The second operated check valve is connected to a second pilot passage for introducing pressure on the pump side of the first check valve in the first oil passage, and normally blocks flow from the cylinder device side to the tank side. As described above, when the pressure is introduced from the second pilot path, it is configured to allow the flow from the cylinder device side to the tank side.

[0007] In the above means, the operating oil in the tank is sucked up through the filter with the operation of the pump,
When sucked into the pump via the tank oil passage, the hydraulic oil compressed by the pump is discharged to the first oil passage. First
Hydraulic oil in the oil passage is supplied from the first port of the cylinder device to the first chamber via the first check valve, so that the piston of the cylinder device is pushed in the direction of the second chamber and a predetermined work is performed through the piston rod. Execute As the piston is pushed in the direction of the second chamber, the hydraulic oil in the second chamber is discharged to the second oil passage. At this time, the second operation check valve is
Since the passage from the cylinder device side to the tank side is allowed by the introduction of the oil passage pressure,
The hydraulic oil discharged to the second oil passage is directly returned to the tank through the second tank return oil passage and the second operation check valve.

Since the hydraulic oil discharged from the cylinder chamber of the cylinder device is once returned to the tank, the hydraulic oil circulating in the entire hydraulic control circuit of the cylinder device is always forced to pass through the filter. Become. Therefore, wear powder and the like mixed in the hydraulic oil are always removed by the filter arranged in the tank oil passage,
It is possible to prevent abnormal wear and seizure caused by abrasion powder or the like interposed in a sliding portion of a cylinder device, a pump, or the like, and an operation abnormality or a pressure abnormality due to biting by a switching valve.

[0009]

FIG. 1 is a circuit diagram showing a hydraulic control circuit of a cylinder device according to an embodiment of the present invention. FIG.
Are each schematic diagram for explaining the operation of the pump,
(A) shows when the pump is rotating forward, and (b) shows when the pump is rotating backward.

In the present embodiment, the hydraulic control circuit of the cylinder device according to the present invention is configured as a hydraulic control circuit of a cylinder device used for a cylinder device for a cab tilt, a cylinder device for opening and closing a wing, a cylinder device for opening and closing a tailgate, and the like. Have been. The cylinder device 11 includes a main body 12 in which a cylinder chamber 13 is formed, and a first port 14 and a second port 15 are opened at both ends of the main body 12 so as to communicate with the cylinder chamber 13.
A piston 18 is inserted into the cylinder chamber 13 of the main body 12 so as to be reciprocally movable, and the interior of the cylinder chamber 13 is partitioned into a first chamber 16 and a second chamber 17 by the piston 18. A piston rod 19 is connected to the end face of the piston 18 on the second chamber 17 side at a right angle. The piston rod 19 projects outside from the end face wall of the second chamber 17 and is connected to a load (not shown). I have.

A reservoir tank (hereinafter, referred to as a tank) 20 and a radial plunger pump 21 as a forward / reverse rotating pump are connected to the cylinder device 11 via a direction switching valve. A radial plunger pump (hereinafter, referred to as a pump) 21 includes a circular cam ring 22 in which a distribution shaft and a rotor are eccentrically mounted. The distribution shaft 23 has a first port 24 and a second port 2
5 are opened in a substantially crescent shape, respectively, and a first communication path 26 and a second communication path 27 are connected to the first port 24 and the second port 25, respectively. A shuttle valve 28 is connected to the first communication path 26 and the second communication path 27, and the shuttle valve 28 is connected to the first communication path 26 and the second communication path 27 in response to the pressure of the first communication path 26 and the second communication path 27. Connection with tank communication path 29 or second communication path 27 and tank communication path 29
It is configured to switch the connection with.

The rotor 30 is provided with a plurality of pump chambers 31 formed by through holes, which are arranged at equal intervals in the circumferential direction and are opened radially around the distribution shaft 23. The plungers 32 are respectively slidably accommodated in the radial direction. The outer end surface of each plunger 32 is slidably abutted against the inner peripheral surface of the cam ring 22. The rotor 30 is configured to be rotated forward and backward by a motor 33, and the plunger 32 performs a pumping operation with the rotation of the rotor 30, and the first port 24 is rotated.
And the second port 25 sucks or discharges hydraulic oil.

A directional switching valve (hereinafter, referred to as a switching valve) 34
Is constructed as a 3-port, 3-position, closed-center, pilot switching valve. The tank port 35 of the switching valve 34 is connected to the tank 20 by a tank oil passage 36, and a suction filter (hereinafter, referred to as a filter) 37 is provided at an end of the tank oil passage 36 on the tank 20 side. The tank communication path 29 of the shuttle valve 28 is connected to the tank oil path 36.

The first oil passage 40 and the second oil passage 41 connected to the first load port 38 and the second load port 39 of the switching valve 34 are connected to the first port 1 of the cylinder device 11.
4 and the second port 15, respectively, and the first communication path 26 and the second communication path 2 of the pump 21.
7 respectively. A first slow return valve 42 and a second slow return valve 42 are provided at the cylinder device side end 40a of the first oil passage 40 and the cylinder device side end 41a of the second oil passage 41.
Slow return valve 43, first check valve 44 and second
Check valves 45 are respectively connected. Both the first check valve 44 and the second check valve 45 are configured to block the flow from the cylinder device 11 side to the pump 21 side.

Each of the first oil passage 40 and the second oil passage 41 is branched into a first tank return oil passage 46 and a second tank return oil passage 47 for directly returning hydraulic oil to the tank 20. The first operation return valve 4 is provided in the first tank return oil passage 46 and the second tank return oil passage 47.
Eighth and second operation check valves 49 are provided respectively.

The first operating check valve 48 is connected to a first pilot passage 50 for introducing the pressure on the switching valve 34 side of the second check valve 45 in the second oil passage 41, and the second operating check valve is connected to the first operating check valve 48. 49 has a first oil passage 40
The second pilot path 51 for introducing the pressure on the switching valve 34 side of the first check valve 44 is connected.
The first operation check valve 48 normally prevents flow from the cylinder device 11 side to the tank 20 side,
Further, when pressure is introduced from the first pilot path 50, it is configured to allow flow from the cylinder device 11 side to the tank 20 side. The second operation check valve 49 is configured to prevent the flow from the cylinder device 11 side to the tank 20 side during normal operation, and to prevent the second pilot path 51 from flowing.
When a pressure is introduced from the cylinder, a flow from the cylinder device 11 side to the tank 20 side is allowed.

The first oil passage 40 and the second oil passage 41
A relief path 52 and a second relief path 53 are connected to communicate with the tank 20, respectively. A first relief valve 54 and a second relief valve 55 are connected to the first relief path 52 and the second relief path 53, respectively. Each is interposed.

The operation of the hydraulic control circuit 10 of the cylinder device having the above configuration will be described.

When the switching valve 34 is switched during the forward rotation of the motor 33 and the tank port 35 is connected to the second load port 39, the operating oil in the tank 20 is sucked up through the filter 37 with the forward rotation of the rotor 30. Of the pump 21 via the second oil passage 41 and the second communication passage 27.
It is sucked into the port 25. With the rotation of the rotor 30,
The hydraulic oil compressed by the plunger 32 is supplied to the pump 21
From the first port 24 to the first oil passage 40.

The hydraulic oil in the first oil passage 40 is supplied to the first check valve 4
The air is supplied from the first port 14 of the cylinder device 11 to the first chamber 16 via the fourth and first slow return valves 42. Since the piston 18 of the cylinder device 11 is pushed toward the second chamber 17 by the supply of the hydraulic oil, the piston rod 19 gradually projects from the main body 12 to perform a predetermined work.

As the piston 18 is pushed in the direction of the second chamber 17, the operating oil in the second chamber 17 is discharged from the second port 15 to the cylinder device side end 41 a of the second oil passage 41. At this time, when the pressure of the first oil passage 40 is introduced, the second operation check valve 49
The hydraulic fluid discharged to the cylinder device side end 41a of the second oil passage 41 is supplied to the second slow return valve 43 and the second tank return oil passage because the flow from the side to the tank 20 is permitted. 47, it is returned directly to the tank 20 through the second operation check valve 49.

Here, if the hydraulic oil sucked up in the second port 25 on the suction side of the pump 21 is insufficient,
The performance of the pump 21 is reduced, and abnormal vibration and abnormal sound are generated. However, in the present embodiment, the second communication path 2 connected to the second port 25 on the suction side of the pump 21
7 is supplied with hydraulic oil via the tank communication path 29 and the tank oil path 36 of the shuttle valve 28, so that the pump 2
There is no shortage of hydraulic oil in the second port 25, which is the suction side of 1. Moreover, the hydraulic oil supplied via the shuttle valve 28 also passes through the filter 37 via the tank oil passage 36, so that the hydraulic oil is always filtered.

When the switching valve 34 is switched during the reverse rotation of the motor 33 and the tank port 35 is connected to the first load port 38, the hydraulic oil in the tank 20 is sucked up through the filter 37 with the reverse rotation of the rotor 30. , The first oil passage 40 and the first
Inhaled into port 24. With the rotation of the rotor 30,
The hydraulic oil compressed by the plunger 32 is supplied to the pump 21
Is discharged from the second port 25 to the second oil passage 41.

The operating oil in the second oil passage 41 is supplied to the second check valve 4.
The air is supplied to the second chamber 17 from the second port 15 of the cylinder device 11 via the fifth and second slow return valves 43. Since the piston 18 of the cylinder device 11 is pushed in the direction of the first chamber 16 by the supply of the hydraulic oil, the piston rod 19 is gradually drawn into the main body 12 and performs a predetermined work.

As the piston 18 is pushed toward the first chamber 16, the hydraulic oil in the first chamber 16 is discharged from the first port 14 to the cylinder device side end 40 a of the first oil passage 40. At this time, the first operating check valve 48 operates the cylinder device 11 by introducing the pressure of the second oil passage 41.
The hydraulic oil discharged to the cylinder device side end 40a of the first oil passage 40 is supplied to the first slow return valve 42 and the first tank return oil passage because the flow from the side to the tank 20 is permitted. 46, it is returned directly to the tank 20 through the first operation check valve 48.

Here, if the hydraulic oil sucked up at the first port 24 on the suction side of the pump 21 becomes insufficient,
The performance of the pump 21 is reduced, and abnormal vibration and abnormal sound are generated. However, in the present embodiment, the first communication path 2 connected to the first port 24, which is the suction side of the pump 21,
6 is supplied with hydraulic oil via the tank communication path 29 and the tank oil path 36 of the shuttle valve 28, so that the pump 2
There is no shortage of hydraulic oil at the first port 24, which is the suction side of 1. Moreover, the hydraulic oil supplied via the shuttle valve 28 also passes through the filter 37 via the tank oil passage 36, so that the hydraulic oil is always filtered.

According to this embodiment, the hydraulic oil discharged from the cylinder device 11 is not supplied to the suction side of the pump 21 but is supplied to the tank 20 by the first tank return oil passage 46 or the second tank return oil passage 47. Since all are returned once, the phenomenon that the hydraulic oil reciprocates between the cylinder device 11 and the pump 21 does not occur. In other words, all the hydraulic oil that has returned to the tank 20 is sucked up by the pump 21 through the filter 37, so that it is necessarily filtered by the filter 37. In other words, the hydraulic control circuit 1 of the cylinder device
Hydraulic oil circulating in the entirety of 0 is always passed through the filter 37 and filtered, so that wear powder and the like mixed in the hydraulic oil due to long-term use of the hydraulic control circuit 10 of the cylinder device are always removed. As a result, abnormal wear and seizure caused by abrasion powder or the like interposed in the sliding portion of the cylinder device 11 or the pump 21 or the like, and abnormal operation or abnormal pressure due to biting by the switching valve 34 are prevented beforehand. Will be.

Moreover, even if the hydraulic oil discharged from the cylinder device 11 is all returned to the tank 20 once by the first tank return oil passage 46 or the second tank return oil passage 47, the hydraulic oil is supplied to the suction side of the pump 21. Is supplied via the tank communication path 29 and the tank oil path 36 of the shuttle valve 28, so that there is no shortage of hydraulic oil on the suction side of the pump 21. Therefore, a decrease in the performance of the pump 21 due to a shortage of hydraulic oil sucked up on the suction side of the pump 21 and occurrence of abnormal vibration and abnormal sound are prevented beforehand.

Further, the hydraulic oil supplied via the shuttle valve 28 also passes through the filter 37 by passing through the tank oil passage 36, so that the hydraulic oil bypassing the switching valve 34 is always filtered.

The present invention is not limited to the above embodiment, and it goes without saying that various changes can be made without departing from the scope of the invention.

For example, the cylinder device is not limited to a single-rod double-acting cylinder device, and may be a double-rod double-acting cylinder device. The pump is not limited to a radial plunger pump, but may be an axial plunger pump, or the like. A positive displacement pump can be used. Further, the switching valve is not limited to the structure of the embodiment.

The switching valve and the shuttle valve are not limited to both, and one of them may be omitted.

Further, the means for switching the flow of the hydraulic oil in accordance with the forward / reverse rotation of the pump may be configured as shown in FIG. That is, in FIG.
In the forward rotation of the second, the second switching check valve 57 permits the flow and the first switching check valve 56 blocks the flow,
The hydraulic oil is supplied from the filter 37 → the tank oil passage 36 → the second switching check valve 57 → the second port 25 of the pump 21 → the first port 24 → the first check valve 44 → the first slow return valve 42 → the cylinder device 11 It flows with the first chamber 16. When the pump 21 rotates in the reverse direction, the first switching check valve 5
6 permits the flow and the second switching check valve 57 blocks the flow, so that the hydraulic oil is supplied from the filter 37 to the tank oil passage 3.
6 → first switching check valve 56 → first port 24 of pump 21 → second port 25 → second check valve 45 → second slow return valve 43 → second chamber 17 of cylinder device 11
And flows. The operation of discharging the hydraulic oil is the same as in the above-described embodiment using the switching valve and the shuttle valve.

Needless to say, the shuttle valve 28 may be used in combination with the configuration using the first switching check valve 56 and the second switching check valve 57 shown in FIG. In short, what is necessary is just to comprise so that the supply destination of hydraulic oil may be switched at the time of forward rotation and reverse rotation of a pump.

[0035]

As described above, according to the present invention,
Hydraulic oil circulating in the entire hydraulic control circuit of the cylinder device always passes through the filter, so that abrasion powder mixed in the hydraulic oil is always filtered. It is possible to prevent abnormal wear and seizure caused by interposition, abnormal operation due to biting by the switching valve, abnormal pressure and the like.

In the case where hydraulic oil is supplied to the suction side of the pump via the tank communication path and the tank oil path of the shuttle valve, it is possible to prevent a phenomenon in which the hydraulic oil is insufficient on the suction side of the pump. Therefore, it is possible to prevent the performance of the pump from deteriorating due to a shortage of hydraulic fluid sucked up on the suction side of the pump, and the occurrence of abnormal vibration and abnormal noise.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a hydraulic control circuit of a cylinder device according to an embodiment of the present invention.

FIGS. 2A and 2B are schematic diagrams for explaining the operation of the pump, where FIG. 2A shows a case where the pump rotates forward and FIG. 2B shows a case where the pump rotates reversely.

FIG. 3 is a circuit diagram showing a hydraulic control circuit of a cylinder device according to another embodiment of the present invention.

[Description of sign]

10: Cylinder device hydraulic control circuit, 11: Cylinder device, 12: Main body, 13: Cylinder chamber, 14: First port, 15: Second port, 16: First chamber, 17: Second chamber,
18 Piston, 19 Piston rod, 20 Reservoir tank, 21 Radial plunger pump (pump), 22 Cam ring, 23 Distribution shaft, 24 First port, 25 Second port, 26 First communication path , 27 ... second communication path, 28 ... shuttle valve, 29 ... tank communication path, 3
0: rotor, 31: pump room, 32: plunger, 33
... Motor, 34 ... Direction switching valve (switching valve), 35 ... Tank port, 36 ... Tank oil passage, 37 ... Suction filter (filter), 38 ... First load port, 39 ... Second load port, 40 ... First Oil passage, 41 ... second oil passage, 42 ... first
Slow return valve, 43 ... second slow return valve, 44
... First check valve, 45 ... Second check valve, 46 ... First
Tank return oil passage, 47 ... second tank return oil passage, 48 ... first operated check valve, 49 ... second operated check valve, 50 ... first pilot path, 51 ... second pilot path, 52 ... first relief path , 53 ... second relief road, 5
4 ... First relief valve, 55 ... Second relief valve, 56 ... First switching check valve, 57 ... Second switching check valve.

Claims (1)

[Claims] A cylinder device having a first port and a second port partitioned by a piston into a first chamber and a second chamber, and a piston rod inserted through the second chamber; A forward / reverse rotating pump interposed between the first oil passage and the second oil passage connected to the second port, a tank connected to the pump via a tank oil passage, and the tank oil passage, A hydraulic control circuit for a cylinder device comprising a filter interposed at a tank side end of the cylinder device, wherein the first oil passage and the second oil passage are prevented from flowing from the cylinder device side to the pump side. A first check valve and a second check valve, each of which is arranged to perform an operation, and a first tank that returns hydraulic oil to the tank in the first oil passage and the second oil passage. The first oil return passage is connected to the second oil return passage, and the first oil return return passage is connected to the second oil return passage. A first pilot path for introducing the pressure of the second check valve on the pump side is connected;
Normally, it is configured to block the flow from the cylinder device side to the tank side, and to allow the flow from the cylinder device side to the tank side when pressure is introduced from the first pilot path, A second operated check valve is interposed in the second tank return oil passage, and the second operated check valve is used for introducing a pressure of the first check valve in the first oil passage on the pump side. 2 pilot roads are connected,
Normally, it is configured to prevent the flow from the cylinder device side to the tank side and to allow the flow from the cylinder device side to the tank side when pressure is introduced from the second pilot path. Characteristic hydraulic control circuit of cylinder device.