JP3194018B2 - Differential cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a differential cylinder.

[0001]

2. Description of the Related Art A differential cylinder is used as a so-called hydraulic cylinder, and its use form is shown in a circuit diagram, for example, as shown in FIG.

That is, in principle, the differential cylinder 1 has a rod body 12 inserted in a cylinder body 11 so as to be able to protrude and retract, and is slidably housed in the cylinder body 11 so that the rod body 12 A rod-side chamber R1 and a piston-side chamber R2 are formed in the cylinder body 11 by a piston 13 connected to the tip.
Are formed by partitioning.

[0003] A discharge hydraulic pressure from a bidirectional pump P as a hydraulic pressure source is supplied to a rod side chamber R1 via a compression side oil passage L1, and a bidirectional pump P is supplied to a piston side chamber R2.
Is supplied via the extension-side oil passage L2.

A rod side chamber R1 is provided in the pressure side oil passage L1.
A check valve C for preventing a so-called backflow of hydraulic oil from the oil supply side to the bidirectional pump P side is provided, and a pressure side oil passage L1 and a growth side oil passage L2 between the check valve C and the rod side chamber R1. An electromagnetic switching valve V is disposed in a communication path L3 that communicates with.

The two-way pump P has a reservoir tank T
The hydraulic oil is sucked through the pilot switching valve Vp, and the discharge oil pressure is set by the relief valve Vr.

[0006] The pilot switching valve Vp is configured to switch the hydraulic pressure discharged from the bidirectional pump P to the compression-side oil passage L1 and the expansion-side oil passage L2 as pilot pressure.

Therefore, according to the conventional differential cylinder 1, that is, according to the circuit for its operation, the differential cylinder is selected by selecting the rotation direction of the bidirectional pump P and controlling the electromagnetic switching valve V accordingly. 1 can be expanded and contracted.

[0008]

However, when the above-described conventional differential cylinder 1 is used,
The following disadvantages have been pointed out.

That is, when this type of differential cylinder 1 is used, as described above, the arrangement of the electromagnetic switching valve V and the check valve C is indispensable in the circuit for its operation. When the switching valve V and the check valve C are individually provided, a device having the circuit, that is, a device equipped with the differential cylinder 1 of this type is so-called bulky, and its size is increased. For example, the mountability of the device on a vehicle is reduced.

The electromagnetic switching valve V and the check valve C
Is expensive in itself, and therefore, the cost of the entire device equipped with this type of differential cylinder 1 tends to increase, and there is a fear that the versatility of the device cannot be expected.

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a simple structure as well as to enable a predetermined operation. An object of the present invention is to provide a differential cylinder which can avoid an increase in the size and cost of the apparatus and is optimal for expecting an improvement in versatility.

[0012]

In order to achieve the above-mentioned object, the present invention is directed to a vehicle, wherein a rod body is slidably housed in a cylinder body via a piston, and the piston includes a rod side chamber and a piston inside the cylinder body. When the hydraulic pressure is supplied from the hydraulic pressure source to the rod-side chamber via the pressure-side oil passage, the rod-side chamber contracts, and when the hydraulic pressure is supplied to the piston-side chamber via the extension-side oil passage, the piston-side chamber and the rod-side chamber are separated from each other. In a differential cylinder that is extended by a differential pressure, an outer cylinder is disposed outside the cylinder body, a sealing member is provided at an end of the cylinder body and the outer cylinder, and the pressure-side oil passage is defined as a cylinder body. It comprises a passage formed between the outer cylinder and a compression-side port formed in the sealing member, and the expansion-side oil passage includes an expansion-side port formed in the sealing member. Branch from port to piston side chamber And a pilot check valve for selectively opening and closing the passage between the cylinder body and the outer cylinder to the pressure side port or the piston side chamber is formed in the communication port. It is assumed that.

[0013]

Therefore, when the oil pressure from the oil pressure source is supplied to the pressure side oil passage, the pilot check valve moves by the oil pressure at that time, and the communication between the passage and the piston side chamber is cut off.

As a result, the hydraulic pressure from the hydraulic pressure source is supplied to the rod-side chamber of the differential cylinder, and at this time, the hydraulic oil in the piston-side chamber of the differential cylinder is discharged to the reservoir tank through the extension-side oil passage. The differential cylinder is contracted.

When the hydraulic pressure from the hydraulic pressure source is supplied to the piston side chamber via the oil path on the extension side, the pilot check valve is moved by the hydraulic pressure at that time, and the communication between the passage and the hydraulic pressure source is cut off.

As a result, the hydraulic pressure from the hydraulic pressure source is supplied to the piston side chamber, and at this time, the rod side chamber is on the low pressure side,
Therefore, the hydraulic oil in the rod side chamber flows into the piston side chamber,
The differential cylinder is extended.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the illustrated embodiment, the mode of use of the differential cylinder according to the present invention is basically the same as that of the above-described conventional example. , As shown in FIG.

That is, the differential cylinder 1 is, in principle, similar to the case of the above-described conventional example, in which the rod 12 is inserted through the cylinder 11 so as to be able to protrude and retract, and the differential cylinder 1 slides inside the cylinder 11. A rod-side chamber R1 and a piston-side chamber R2 are formed in the cylinder body 11 by a piston 13 movably housed and connected to the tip of the rod body 12.

The hydraulic pressure discharged from the bidirectional pump P as a hydraulic pressure source is supplied to the rod-side chamber R1 through a hydraulic oil path L1, and the bidirectional pump P is supplied to the piston-side chamber R2.
Is supplied via the extension-side oil passage L2.

On the other hand, in this circuit configuration, between the differential cylinder 1 and the hydraulic pressure source P, the compression side oil passage L1 and the expansion side oil passage L
2 is provided so as to communicate with the valve structure 2.

That is, the valve structure 2 is set in the form of a pilot switching valve. When the hydraulic pressure discharged from the bidirectional pump P is supplied to the pressure side oil passage L1, the hydraulic pressure is switched as the pilot pressure. A pressure-side check position 2a that is set and a expansion-side check position 2b that is switched as a pilot pressure when the hydraulic pressure discharged from the bidirectional pump P is supplied to the expansion-side oil passage L2.

The pressure-side check position 2a is
The discharge hydraulic pressure from the bidirectional pump P is prevented from being supplied to the expansion-side oil passage L2. The expansion-side check position 2b is such that the discharge hydraulic pressure from the bidirectional pump P is supplied to the reservoir tank T via the compression-side oil passage L1. It is set to prevent that.

The bidirectional pump P draws hydraulic oil from the reservoir tank T via the pilot switching valve Vp and sets the discharge oil pressure by the relief valve Vr, as in the case of the above-described conventional example. And

The pilot switching valve Vp is configured so that the hydraulic pressure discharged from the bidirectional pump P to the compression-side oil passage L1 and the expansion-side oil passage L2 can be switched as the pilot pressure.

FIG. 2 shows a specific embodiment based on the circuit configuration of FIG. The differential cylinder 1 shown in FIG.
A rod body 12 is inserted into a cylinder body 11 through a piston 13.
Is slidably housed, and the piston 13 is
A rod-side chamber R1 and a piston-side chamber R2 are defined therein. The rod-side chamber R1 contracts when a hydraulic pressure is supplied from a hydraulic pressure source to the rod-side chamber R1 via a compression-side oil passage L1, and a hydraulic pressure is applied to the piston-side chamber R2 via an extension-side oil passage L2. Is supplied when the piston side chamber R2 is supplied.
And the rod side chamber R1 is extended by the pressure difference. Further, in the present invention, an outer cylinder 15 is further provided outside the cylinder body 11, a sealing member 14 is provided at an end of the cylinder body 11 and the outer cylinder 15, and the pressure side oil passage L1 is connected to the cylinder body 11 and the outer cylinder. 15 and the pressure side ports 14a, 14c, 14e formed in the sealing member 14.
, And the extension side oil passage L2 is constituted by extension side ports 14 b and 14 f formed in the sealing member 14. Further, the sealing member 14 is formed with a communication port 14d that branches off from the pressure side port 14c and opens to the piston side chamber R2, and the cylinder body 11 and the outer cylinder 15 are formed in the communication port 14d.
The pilot check valve 18 selectively opens and closes the passage L4 between the pressure side port 14c and the piston side chamber R2.
Is movably inserted. This will be described in more detail below.

In the differential cylinder 1, the cylinder body 1
An outer cylinder 15 is provided on the outer periphery of the cylinder body 1, an annular passage L4 is formed between the outer cylinder 15 and the cylinder body 11, and the annular passage L4 is formed with a communication hole 11 a formed in the cylinder body 11. It communicates with the rod-side chamber R1 in the cylinder body 11 through this.

A shaft sealing member that allows the rod body 12 to be slidably inserted into the shaft center portion of the rod body R1 side end of the cylinder body 11 and the open end of the outer cylinder 15 that is oriented in the same direction. 16 is sealed.

The sealing member 14 is also provided with the shaft sealing member 1.
As in the case of 6, it goes without saying that the open end, which is the lower end in the figure, of the outer cylinder 15 is sealed.

The sealing member 14 is communicated with one of the ports 14a and 14b, which are formed by screw holes radially opened so as to form the compression-side oil passage L1 and the expansion-side oil passage L2, respectively, and one of the ports 14a. A port 14c which is opened in the axial direction in a direction communicating with the piston side chamber R2 in the cylinder body 11, and which is extended from the port 14c and is axially opened so as to be connected to the piston side chamber R2. A communication port 14d, a port 14e radially opened to communicate with the communication port 14d and the annular passage L4, and a communication with the other port 14b and communication with the piston side chamber R2. And a port 14f that is opened in the axial direction as described above.

In the present invention, the communication port 14d is a communication passage which enables communication between the pressure side oil passage L1 and the expansion side oil passage L2 via the piston side chamber R2. A cylindrical seat member 17 is fitted to the end of the communication port 14d on the side of the piston-side chamber R2 of the communication port 14d, and a poppet-type pilot check valve 18 as a blocking member is disposed in the communication port 14d. I have.

When the check valve 18 moves in the illustrated state, that is, in the upward direction in the figure, it is adjacent to the seat member 17 and cuts off the communication of the communication port 14d with the piston side chamber R2. And communication port 1
A communication port 4e of 4d, that is, communication with the annular passage L4 is enabled.

On the other hand, when the check valve 18 moves in the downward direction in the figure as shown by the broken line in the figure, the check valve 18 is adjacent to the open end of the port 14c, and the communication port 14d The communication with the port 14c is cut off, and the communication of the communication port 14d, that is, the port 14e communicating with the annular passage L4, is enabled to communicate with the piston side chamber R2.

Therefore, in the differential cylinder 1 having the valve structure 2 formed as described above, when the hydraulic pressure from the bidirectional pump P, which is the hydraulic pressure source, is supplied to the pressure side oil passage L1, the hydraulic pressure is reduced. Port 14 forming a part of compression-side oil passage L1
a and a communication port 14 serving as a communication path via the port 14c
d. At this time, the communication port 1
The check valve 18 disposed in 4d moves to the state shown in the drawing, and the communication of the communication port 14d to the piston side chamber R2 is prevented.

As a result, the hydraulic pressure supplied to the communication port 14d is applied to the communication port 14e, the annular passage L4, and the communication hole 11d.
This is supplied to the rod-side chamber R1 via a.

At this time, the piston side chamber R2 is
The cylinder body 11 is connected to the reservoir tank T via a port 14f which forms a part of the extension port L2.
Inside, the piston 13 slides on the pressure side so as to descend in the figure, and the differential cylinder 1 can be contracted.

On the other hand, when the hydraulic pressure from the bidirectional pump P is supplied to the extension side oil passage L2, the hydraulic pressure is applied to the port 14b.
Is supplied to the piston side chamber R2 via the port 14f and the hydraulic pressure supplied to the piston side chamber R2 reaches the communication port 14d.
The check valve 18 disposed in 4d moves in the downward direction in the figure as shown by the broken line in the figure, and the communication of the communication port 14d to the pressure side oil passage L1 is prevented. At the same time, communication between the communication port 14d and the port 14e, that is, communication with the rod side chamber R1 via the annular passage L4 and the communication hole 11a is enabled.

As a result, the hydraulic pressure from the bidirectional pump P is supplied to the piston side chamber R2, so that the pressure in the pressure receiving area causes the rod side chamber R1 to be on the low pressure side. By flowing into the piston side chamber R2 through the passage L4 and the ports 14e and 14d, the piston 13 slides in the cylinder body 11 to the extension side so as to rise in the figure, The extension of the differential cylinder 1 becomes possible.

[0038]

As described above, according to the present invention, the valve structure for controlling the expansion and contraction of the differential cylinder only needs to dispose the pilot check valve movably in the communication passage. With this configuration, it is possible to dispose the valve structure in a sealing member connected to the cylinder body, and therefore, it is possible to realize a simple structure to control the expansion and contraction of the differential cylinder, and There is an advantage that it is possible to reduce the number of members as a single unit in a device equipped with a differential cylinder. Furthermore, since the extension-side oil passage and the communication port are connected via the piston-side chamber, the piston-side chamber has a function as a pressure chamber and a function as a flow path. The configuration of the flow path can be simplified, the number of processing steps is small, and the cost can be reduced.

Further, according to the present invention, the hydraulic cylinder, the pilot switching valve and the like are provided in the housing member in which the valve structure is disposed, so that the components related to the differential cylinder are unitized. There is an advantage that it becomes possible.

As a result, according to the present invention, it is possible to avoid an increase in the size and cost of the device equipped with the differential cylinder, and, for example, to improve the mountability on a vehicle.
It is optimal for expecting improvement in versatility.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a mode of using a differential cylinder according to the present invention.

FIG. 2 is a partial longitudinal sectional view showing a differential cylinder according to one embodiment of the present invention together with a circuit diagram.

FIG. 3 is a circuit diagram showing a mode of using a differential cylinder as a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Differential cylinder 2 Valve structure 11 Cylinder body 12 Rod body 14 Sealing member 14a, 14b, 14c, 14e, 14f Port 14d Communication port 15 Outer cylinder 18 Pilot check valve 19 Housing member L1 Pressure side oil path L2 Extension side oil path L4 Passage P Bidirectional pump as hydraulic source R1 Rod side chamber R2 Piston side chamber

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-216103 (JP, A) JP-B 41-12122 (JP, B1) JP-B 40-24216 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) F15B 11/00-11/22 F15B 15/00-15/28

Claims (1)

(57) [Claims] 1. A rod body is slidably housed in a cylinder body via a piston, and the piston partitions a rod side chamber and a piston side chamber in the cylinder body, and the rod side chamber is connected to the rod side chamber via a pressure side oil passage from a hydraulic source. In a differential cylinder, which contracts when hydraulic pressure is supplied and is expanded by the pressure difference between the piston side chamber and the rod side chamber when hydraulic pressure is supplied to the piston side chamber via the expansion side oil passage, the outside of the cylinder body And a sealing member provided at the end of the cylinder body and the outer cylinder, and a pressure side port formed in the sealing member and a passage formed in the pressure side oil passage between the cylinder body and the outer cylinder. The expansion-side oil passage is configured by an expansion-side port formed in a sealing member, and the sealing member further includes a communication port that branches from the compression-side port and opens to the piston-side chamber. In the port is the above syringe A differential cylinder, wherein a pilot check valve for selectively opening and closing a passage between a damper body and an outer cylinder is selectively inserted into the pressure side port or the piston side chamber.