JP2002226186A - Hydraulic jack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic jack enabling smooth movement of an accumulator piston. SOLUTION: An accumulator cylinder 15 and the accumulator piston 18 for accumulating the hydraulic pressure generated inside a cylinder main body 1 from the weight of a load 44 connected to the top of a ram 3 are mounted on the outer periphery of the cylinder main body 1. The accumulator piston 18 is divided into a first piston 18a slidably abutting to the outer surface of the cylinder main body 1 and a second piston 18b slidably abutting to the inner surface of the accumulator cylinder 15, and the first and second pistons 18a and 18b are connected to each other in such a way that the pistons are relatively movable in the radial direction of the accumulator cylinder 15. Therefore, if the cores of the cylinder main body 1 and the accumulator cylinder 15 are deviated from each other or there is unevenness in the precision in the work on the outer surface of the cylinder main body 1 and the inner surface of the accumulator cylinder 15, the first and second pistons 18a and 18b are relatively moved to absorb the core deviation or the unevenness, so that the accumulator piston moves smoothly. As a result, the position energy of the load 44 can be accumulated without loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic jack having a pressure accumulating means provided on an outer periphery of a cylinder body, and more particularly to a hydraulic jack having a smooth operation of a pressure accumulating piston.

[0002]

2. Description of the Related Art Conventionally, a hydraulic jack used as a drive source or the like has a ram b projecting from a cylinder a as shown in FIG. 5, for example, and a load c to be driven is connected to the tip of the ram b. Have been. A hydraulic pump e is connected to the cylinder a via a control valve d.
By controlling the discharge pressure supplied to the cylinder a by the control valve d, the load c can be raised and lowered by the ram b.

However, in the above-described conventional hydraulic jack, when the load c is lowered, the pressure oil in the cylinder a is discharged from the control valve d to the tank f, so that the potential energy of the load c is wasted. There is a problem that goes wrong.

[0004] In order to solve such a problem, when the load c is lowered, the potential energy of the load c is stored as hydraulic pressure in the pressure accumulating means, and when the load c is subsequently raised, the hydraulic pressure stored in the pressure accumulating means is stored in the cylinder. Hydraulic jacks have been put to practical use to save energy by supplying them to a.

[0005]

However, in the above-mentioned conventional hydraulic jack, since the pressure accumulating means is provided separately from the hydraulic cylinder, a space for installing the pressure accumulating means is required, and the hydraulic cylinder and the pressure accumulating means are connected by piping. Since it is necessary to make connection, there is a problem such as an increase in equipment cost.

The present invention has been made to solve such a conventional problem. By providing the pressure accumulating means on the outer periphery of the cylinder body, the space for installing the pressure accumulating means,
It is an object of the present invention to provide a hydraulic jack in which the pipe connecting the cylinder body and the pressure accumulating means is not required, and the pressure accumulating piston has a divided structure to facilitate the operation.

[0007]

According to the first aspect of the present invention, there is provided a cylinder body in which a head side and a bottom side are closed by end plates, a base end side is accommodated in the cylinder body, and A hydraulic jack comprising a ram having a distal end slidably penetrating an end plate provided on the head side of the cylinder body, and a ram protruding to the outside of the cylinder body. A pressure accumulating cylinder is provided concentrically, and the pressure accumulating cylinder is partitioned into a pressure accumulating chamber and a gas chamber by a pressure accumulating piston provided between the pressure accumulating cylinder and the cylinder body, and the pressure accumulating chamber communicates with the inside of the cylinder body. The gas chamber 1 is filled with a compressed inert gas, and the pressure accumulating piston is slidably contacted with a first piston that is in sliding contact with the outer peripheral surface of the cylinder body and an inner peripheral surface of the pressure accumulating cylinder. That the second is divided into a piston, and these first, in which between the second piston linked to be relatively movable in the radial direction of the accumulator cylinder.

With the above structure, when the load is lowered, the potential energy of the load is stored in the pressure accumulating means as hydraulic pressure, and when the load is subsequently increased, the hydraulic pressure accumulated in the pressure accumulating means can be supplied to the cylinder. Therefore, energy can be saved, and the structure is simpler than when the pressure accumulating means is provided in the cylinder main body.

Further, as compared with the case where the pressure accumulating means is provided in a place different from the cylinder main body, the space for installing the pressure accumulating means is not required, so that the space can be saved and the piping for connecting the cylinder main body and the pressure accumulating means is unnecessary. As a result, it is possible to reduce equipment costs and the like. Further, since the pressure accumulating cylinder is divided into first and second pistons and the first and second pistons are connected to be relatively movable in the radial direction of the pressure accumulating cylinder, the center axis of the cylinder body and the center of the pressure accumulating cylinder are Even if there is misalignment of the shaft, or if there is variation in processing accuracy on the outer peripheral surface of the cylinder body or the inner peripheral surface of the pressure accumulating cylinder, the first and second pistons move relative to each other in the radial direction to reduce the misalignment and variation. Because of the absorption, even when the stroke of the hydraulic jack is long, the pressure accumulating piston does not malfunction, and the pressure accumulating piston operates smoothly, so that the potential energy of the load can be accumulated without waste.

In order to achieve the above object, according to a second aspect of the present invention, the pressure accumulating piston is divided in the axial direction of the pressure accumulating cylinder to form first and second pistons, and these first and second pistons are formed.
The first and second pistons are connected by a fastener inserted into a through hole formed in one of the pistons, and a gap is formed between the fastener and the inner peripheral surface of the through hole.

With the above structure, the first and second pistons relatively move in the radial direction due to the gap formed between the fixing tool and the inner peripheral surface of the through-hole, thereby causing misalignment between the cylinder main body and the pressure accumulating cylinder and processing. In order to absorb variations in accuracy, smooth operation of the pressure accumulating piston is not hindered and
Since it is only necessary to control the processing accuracy of the inner peripheral surface of the piston and the outer peripheral surface of the second piston, the production of the pressure accumulating piston is facilitated.

According to a third aspect of the present invention, a pressure accumulating piston is divided in a radial direction of a pressure accumulating cylinder to form first and second pistons, and a space between the first and second pistons is formed. The first and second pistons are connected by a fastener so that a gap is formed between the first and second pistons, and a seal ring is interposed in the gap between the first and second pistons.

With the above arrangement, the first and second pistons relatively move in the radial direction due to the gap formed between the first and second pistons, causing misalignment between the cylinder body and the pressure accumulating cylinder and variations in machining accuracy. , The smooth operation of the pressure accumulating piston is not hindered, and it is only necessary to control the processing accuracy of the inner peripheral surface of the first piston and the outer peripheral surface of the second piston. Becomes easier.

[0014]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a hydraulic jack, in which a base end of a ram 3 is accommodated in a cylinder body 1, and a distal end of the ram 3 has a bearing cylinder 4 for closing a head-side opening of the cylinder body 1. The end plate 5 penetrates the end plate 5
Projecting upward. The bearing tube 4 supports the vertical movement of the ram 3. A bearing 6 is provided on the inner peripheral surface of the ram 3 for sliding contact with the outer peripheral surface of the ram 3, and the outer peripheral portion is formed on the inner peripheral surface on the upper end side of the cylinder body 1. It is screwed into the threaded portion 1a.

A seal member 7 for preventing the pressure of the hydraulic chamber 1b in the cylinder body 1 from leaking from the screw portion 1a is provided between the inner peripheral portion on the upper end side of the cylinder body 1 and the outer peripheral portion on the upper end side of the bearing cylinder 4. The end plate 5 is removably attached to a flange 4a which is interposed and protrudes from the upper end of the bearing cylinder 4 by a fixing tool 8 such as a bolt. An annular seal groove 4b is formed on the upper surface of the flange 4a protruding from the bearing cylinder 4 so as to surround the periphery of the ram 3, and the flange 4a is formed by the seal member 9 inserted into the seal groove 4b. The pressure in the hydraulic chamber 1b in the cylinder body 1 is prevented from leaking from between the inner peripheral surface of the ram 3 and the outer peripheral surface of the ram 3. The inner peripheral surface is pressed against the outer peripheral surface of the ram 3 by being pressed by the annular ridge 5 a.

The lower end opening of the cylinder body 1 is closed by an end plate 10 having a diameter larger than the outer diameter of the cylinder body 1. The end plate 10 has an annular groove 10a formed in the center of the upper surface, and the inner periphery of the annular groove 10a is screwed into a screw portion 1c formed on the inner peripheral surface on the lower end side of the cylinder body 1. A seal member 11 for preventing the pressure of the hydraulic chamber 1b in the cylinder body 1 from leaking from the threaded portion 1b is interposed between the inner peripheral surface of the cylinder 1 and the inner peripheral surface of the annular groove 10a.

On the other hand, pressure accumulating means 1
4 are provided. The pressure accumulating means 14 includes the cylinder body 1
It has a pressure accumulating cylinder 15 having a sufficiently large diameter, and a lower end of the pressure accumulating cylinder 15 is fixed to an annular stepped portion 10b of an end plate 10 provided at a lower end portion of the cylinder main body 1 so that bolts or the like are fixed. The cylinder body 1 and the pressure accumulating cylinder 15 are detachably attached to the end plate 10 by a tool 16 between the inner peripheral surface on the lower end side of the pressure accumulating cylinder 15 and the annular step portion 10b.
A seal member 17 for preventing the pressure in the pressure accumulating chamber 15a formed therebetween from leaking is interposed.

An annular pressure accumulating piston 18 is accommodated in the pressure accumulating cylinder 15, and the pressure accumulating cylinder 15 partitions the pressure accumulating cylinder 15 into a pressure accumulating chamber 15a and a gas chamber 15b. And an inert gas such as nitrogen gas. The accumulator piston 18 operates smoothly even if the center axis of the cylinder body 1 and the center axis of the accumulator cylinder 15 are slightly misaligned.
As shown in FIG. 2, the cylinder is composed of a first piston 18 a and a second piston 18 b divided in the axial direction of the pressure accumulating cylinder 15, and the inner peripheral surface of the first piston 18 a is connected to the cylinder body via a pair of wear rings 19. 1 and a seal ring 20 for oil pressure, which is oil-resistant on the side of the pressure accumulating chamber 15a, between the wear rings 19,
A gas pressure seal ring 21 is provided on the gas chamber 15b side, and the inner peripheral surface is pressed against the outer peripheral surface of the cylinder body 1 respectively.

The outer diameter of the first piston 18a is smaller than the inner diameter of the pressure accumulating cylinder 15;
A gap 18c is formed between the second piston 18b and the inner peripheral surface of the cylinder main body 1. The inner diameter of the second piston 18b is larger than the outer diameter of the cylinder main body 1. A gap 18d is formed.

A plurality of through holes 18e are formed in the second piston 18b in the axial direction at intervals in the circumferential direction, and are fixed by fasteners 23 such as bolts inserted into the through holes 18e. , The first piston 18a and the second piston 18b are connected to each other,
A concave portion 18g is formed on the end surface of the second cylinder 18b so that a does not protrude from the end surface of the second cylinder 18b, and the head portion 23a is housed in the concave portion 18g.

The diameter of the through hole 18e is slightly larger than the outer diameter of the fixing member 23, and a gap 18f is formed between the through hole 18e and the inner peripheral surface. The space between the pistons 18b is slidable in the radial direction, and a seal member 22 is interposed between the sliding surfaces of the first piston 18a and the second piston 18b. The outer peripheral surface of the second piston 18b is slidably contacted with the inner peripheral surface of the pressure accumulating cylinder 15 via a pair of wear rings 24. Between the respective wear rings 24, a hydraulic pressure having oil resistance toward the pressure accumulation chamber 15a is provided. A gas seal ring 25 is provided on the gas chamber 15 b side, and a gas pressure seal ring 26 is provided on the gas chamber 15 b side.

The top opening of the accumulator cylinder 15 is closed by an annular end plate 29, and the end plate 29 is removably attached to the upper end of the accumulator cylinder 15 by fasteners 30 such as bolts. A sealing member for preventing gas pressure in the gas chamber 15b from leaking between the inner peripheral surface of the plate 29 and the outer peripheral surface of the cylinder body 1 and between the outer inner surface of the end plate 29 and the inner peripheral surface of the pressure accumulating cylinder 15. 31, 32 are interposed.

On the other hand, the cylinder body 1 and the pressure accumulating cylinder 15
A hydraulic port 10c and a pressure accumulating port 10d are provided on an end plate 10 provided at the lower end of the
The discharge port 34a and the suction port 34b of the hydraulic pump 34 are connected to c and 10d via pilot check valves 35 and 36, respectively. The discharge port 34a and the suction port 34b of the hydraulic pump 34 are connected to a tank 39 via check valves 37 and 38, and the discharge port 34a and the suction port 34b.
Are connected to relief valves 40 and 41.

In the drawing, reference numeral 42 denotes a motor for driving the hydraulic pump 34, and reference numeral 43 denotes an emergency solenoid valve for lowering the emergency load 44.

Next, the operation of the hydraulic jack constructed as described above will be described. When the hydraulic pump 34 is rotated in the normal direction to raise the load 44 connected to the tip of the ram 3, the pressure is stored in the accumulator chamber 15a of the accumulator cylinder 15. The stored pressure oil is discharged from the suction port 34b of the hydraulic pump 34 to the discharge port 34a, and is supplied to the hydraulic chamber 1b of the cylinder body 1 via the pilot check valve 35. At this time, the pilot check valve 36 on the side of the pressure accumulation port 10d is open.

When the pressure oil is supplied to the hydraulic chamber 1b of the cylinder body 1, the ram 3 is raised, the load 44 connected to the tip of the ram 3 starts to rise, and the rotational speed of the hydraulic pump 34 is reduced. By controlling, the rising speed of the load 44 can be arbitrarily controlled.

The pressure oil pre-accumulated in the accumulator chamber 15a is supplied to the hydraulic chamber 1b in the cylinder body 1 so that the load 44
In order to increase the energy, it is only necessary to supply the energy from the hydraulic pump 34 by the difference between the energy required for increasing the load 44 and the stored energy, thereby achieving a great energy saving. To lower the pressure, the hydraulic pump 34 is rotated in the reverse direction, and the pressure oil in the hydraulic chamber 1 b is supplied to the pressure accumulating chamber 15 a of the accumulator cylinder 15 via the pilot check valve 36.

At this time, due to the load of the load 44, the hydraulic chamber 1b
Since the hydraulic pressure generated inside flows into the accumulator chamber 15a, the hydraulic pump 34 only controls the descending speed of the load 44,
Since almost no driving energy is required, the pressure accumulating piston 18 is raised by the pressurized oil flowing into the pressure accumulating chamber 15a, and the inert gas in the gas chamber 15b is compressed. It becomes possible to accumulate pressure.

Further, the inside of the pressure accumulating cylinder 15 is stored in a pressure accumulating chamber 15a.
The pressure accumulating piston 18 is divided into a first piston 18a and a second piston 18b, which are slidably connected in the radial direction, so that the center of the cylinder body 1 and the center of the accumulating cylinder 15 are separated. Even if there is some misalignment, or the outer peripheral surface of the cylinder body 1 or the inner peripheral surface of the pressure accumulating cylinder 15 has a variation in processing accuracy.
8a and the second piston 18b relatively move in the radial direction of the pressure accumulating cylinder 15 to absorb misalignment and variations.
Even if the stroke of the hydraulic jack is long, the pressure accumulating piston does not malfunction, and the pressure accumulating piston 18
Operates smoothly, so that the potential energy of the load 44 can be accumulated without waste.

On the other hand, while the hydraulic jack has been used for a long period of time, the bearing 6, the sealing members 7, 9, the sealing ring 20,
If the desired output cannot be obtained or the accumulated pressure energy is lost due to wear or deterioration of the bearing 21, maintenance such as replacement of the bearing 6 and the seal members 7, 9, 21, 22 is required. Required.

In maintenance, the bearing cylinder 4 and the end plates 5 and 19 are disassembled and the bearing 6, the sealing members 7, 9 and the seal ring 2 provided on the bearing cylinder 4 and the end plates 5 and 19 are disassembled.
0, 21 is replaced, but the bearing cylinder 4 and the end plates 5, 19
Since the hydraulic cylinder can be removed above the cylinder body 1 and the pressure accumulating cylinder 15, even when the hydraulic cylinder is installed upright in a narrow machine room or the like, the bearing 6, the seal members 7, 9, and the seal rings 20, 21 can be removed. The replacement work can be performed easily in a short time.

In the above embodiment, the first piston 1
The through hole 18e and the fixing member 23 are provided on the 8a side.
The piston 18b may be provided on the side. Further, although the pressure accumulating piston 18 is divided in the axial direction, it may be divided in the circumferential direction as in the modification shown in FIGS.

That is, the pressure accumulating piston 18 of the modified example shown in FIGS. 3 and 4 is divided into two parts in the circumferential direction to form a first piston 18a and a second piston 18b. Between the inner peripheral surface of the second piston 18b, misalignment between the cylinder body 1 and the pressure accumulating cylinder 15,
A gap 18h is provided to absorb variations in processing accuracy. A flange 18i protrudes from the outer periphery of one end of the first piston 18a. A concave step 18j formed on the inner periphery of one end of the second piston 18b is fitted to the flange 18i. 1, the second piston 18a, 1
Lock ring 1 on concave step 18k formed on the other end side of 8b.
8m is fitted, and this locking ring 18m is fixed to the first piston 18a by the fixing member 23,
The first piston 18a and the second piston 18b are connected and integrated.

The inner peripheral surface of the first piston 18a and the second
An O-ring 46 is inserted into an annular groove 18n formed on the outer peripheral surface of the piston 18b, and is provided between the outer peripheral surface of the cylinder body 1 and the inner peripheral surface of the first piston 18a, and of the second piston 18b. A seal is provided between the outer peripheral surface and the inner peripheral surface of the pressure accumulation cylinder 15, and a pair of seal rings 47 are interposed between the outer peripheral surface of the first piston 18a and the inner peripheral surface of the second piston 18b. These seal rings 47
Is housed in an annular groove 18p formed on the outer peripheral surface of the first piston 18a with the back faces facing each other, and a backup ring 48 is provided on the back side.

The operation of the hydraulic jack constructed as described above is the same as that of the above-described embodiment, and a description thereof will be omitted.
Even if there is a slight misalignment between the center of the cylinder body 1 and the central axis of the pressure accumulating cylinder 15, or if there is a variation in processing accuracy on the outer peripheral surface of the cylinder body 1 or the inner peripheral surface of the pressure accumulating cylinder 15, the first piston 18a A gap 18h provided between the hydraulic piston and the second piston 18b absorbs misalignment and variations in machining accuracy, so that even if the stroke of the hydraulic jack is long, the pressure accumulating piston 18 does not malfunction and the accumulating pressure does not increase. Since the piston 18 operates smoothly, the load 44
Can be accumulated without waste.

In the above embodiment, the pressure accumulating cylinder 1
5, the pressure accumulating chamber 15a is provided below the accumulating cylinder 15, and the gas chamber 15b is provided above the accumulating cylinder 15.

[0037]

As described above in detail, according to the present invention, the pressure accumulating means for accumulating the oil pressure generated in the cylinder body by the load of the load connected to the tip of the ram is provided on the outer periphery of the cylinder body. When the load is lowered, the potential energy of the load is stored in the pressure accumulating means as oil pressure, and when the load is subsequently increased, the hydraulic pressure accumulated in the pressure accumulating means can be supplied to the cylinder, thereby saving energy. Since the structure is simpler than the case where the pressure accumulating means is provided in the cylinder main body, it can be easily manufactured and provided at low cost.

Further, since the pressure accumulating means is provided on the outer periphery of the cylinder main body, a space for installing the pressure accumulating means is not required as compared with a case where the pressure accumulating means is provided at a place different from the cylinder main body. At the same time, since piping for connecting the cylinder body and the pressure accumulating means is not required, equipment costs and the like can be reduced.

Further, the pressure accumulating piston is divided into a first piston sliding on the outer peripheral surface of the cylinder body and a second piston sliding on the inner peripheral surface of the pressure accumulating cylinder.
Since the second pistons are connected so as to be relatively movable in the radial direction of the accumulator cylinder, there is a misalignment between the center axis of the cylinder body and the center axis of the accumulator cylinder, or the outer peripheral surface of the cylinder body or the inner part of the accumulator cylinder. Even if there is variation in processing accuracy on the peripheral surface, the first and second pistons relatively move to absorb misalignment and variations, so that even if the stroke of the hydraulic jack is long, the accumulator piston may malfunction. In addition, since the pressure accumulating piston operates smoothly, the potential energy of the load can be accumulated without waste.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a hydraulic jack according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a circle A in FIG. 1;

FIG. 3 is a cross-sectional view showing a modified example of the pressure accumulating piston provided in the hydraulic jack according to the embodiment of the present invention.

FIG. 4 is an enlarged view in a B circle of FIG. 3;

FIG. 5 is an explanatory view showing a conventional hydraulic jack.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder main body 3 Ram 5 End plate 10 End plate 14 Accumulation means 15 Accumulation cylinder 15a Accumulation chamber 15b Gas chamber 18 Accumulation piston 18a First piston 18b Second piston 18e Through hole 18f Gap 18h Gap 23 Fixing tool 44 Load 47 Seal ring

Claims (3)

[Claims] 1. A cylinder body (1) whose head side and bottom side are closed by end plates (5, 10), a base end side of which is housed in the cylinder body (1), and a distal end side of which is a cylinder body (1). A hydraulic jack comprising a ram (3) that slidably penetrates an end plate (5) provided on a head side and protrudes outside a cylinder body (1), wherein the cylinder body (1) Around the
A pressure storage cylinder (15) is provided concentrically with the cylinder body (1),
The pressure accumulating cylinder (15) is partitioned into a pressure accumulating chamber (15a) and a gas chamber (15b) by a pressure accumulating piston (18) provided between the pressure accumulating cylinder (15) and the cylinder body (1). (15a)
And the gas chamber (15b).
The cylinder is filled with a compressed inert gas, and the pressure accumulating piston (18) is slid on the first piston (18a) in sliding contact with the outer peripheral surface of the cylinder body (1) and on the inner peripheral surface of the pressure accumulating cylinder (15). A second piston (18b) in contact therewith and
A hydraulic jack characterized in that the second pistons (18a, 18b) are connected so as to be relatively movable in the radial direction of the pressure accumulating cylinder (15). The pressure accumulating piston (18) is connected to a pressure accumulating cylinder (1).
The first and second pistons (18a, 18b) are formed by dividing in the axial direction of 5), and the through holes (18e) formed in one of the first and second pistons (18a, 18b) are formed. The first and second pistons (18a, 18b) are connected by the inserted fastener (23), and a gap (1) is formed between the fastener (23) and the inner peripheral surface of the through hole (18).
The hydraulic jack according to claim 1, wherein 8f) is formed. 3. The pressure accumulating piston (18) is connected to a pressure accumulating cylinder (1).
First and second pistons (18a, 18b) divided in the radial direction of 5)
And the first and second pistons (18a, 18a) are formed such that a gap (18h) is formed between the first and second pistons (18a, 18b).
b) are connected by a fastener (23), and the first,
Seal ring in the gap (18h) between the second pistons (18a, 18b)
The hydraulic jack according to claim 1, wherein (47) is interposed.