Double Cylinder Type Hydraulic Mechanism

Abstract

A hydraulic mechanism includes an outer cylinder having an expansion side working port and a contraction side working port respectively formed on a top of the outer cylinder; an inner cylinder insertedly installed inside the outer cylinder to come in and out toward a bottom of the outer cylinder; an inner rod having two flow paths respectively connected to the expansion side working port and the contraction side working port, one end of which is fixed to an inner top surface of the outer cylinder, and the other end of which passes through a top of the inner cylinder and protrudes to be positioned inside the inner cylinder; and a piston combined with the other end of the inner rod to be positioned inside the inner cylinder and formed with a hole connected to the flow path of the inner rod connected to the expansion side working port.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit and priority of Korean Patent Application No. 10-2011-0007153 filed Jan. 25, 2011, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic mechanism using hydraulic pressure as a power source, which is capable of supporting weight of a platform (or a mounted structure) in the vertical direction of a cylinder and moving the platform to a desired position. More particularly, the present invention relates to a double cylinder type hydraulic mechanism, which is constructed to normally operate without leakage of hydraulic pressure and working fluid to outside in a poor environment in which a large amount of lateral loads are applied due to modification of the mounted platform or a ground slope, or working parts of the cylinder exposed to outside can be easily damaged because of the surface corroded by contaminated materials such as flames or propellant gas or scratched by bounce of stones.

2. Background of the Related Art

Generally, since a hydraulic mechanism (particularly, a hydraulic jack) has a powerful output per unit weight and a simple structure, it is frequently used at a site of a poor working environment, such as a ground structure work site or a public work site.

FIG. 2 shows vertical cross-sectional views for describing working principles of a conventional hydraulic mechanism, particularly principles of a hydraulic jack.

• • 1. As shown in FIG. 2, the conventional hydraulic jack includes a cylinder 201 penetratingly combining an expansion side working port 205 at an upper side of the cylinder surface and a contraction side working port 206 at a lower side of the cylinder surface; a piston 202 inserted inside the cylinder 201 so as to move in the direction pushed by working fluid when the working fluid is supplied inside the cylinder 201; a rod 203 formed or mounted at the center of any one surface of the piston 202 in one piece to expose one end of the rod to outside of the cylinder 201; a foot plate 204 installed at the one end of the rod 203; a piston seal 207 insertedly fixed to the outer surface of the piston 202, for sustaining lateral loads applied in the radius direction of the cylinder 201 and preventing leakage of the working fluid; and a cylinder seal 208 inserted into the inner surface of a hole positioned on the bottom of the cylinder 201 through which the one end of the rod 203 slidingly passes.

In the configuration so constructed, for example, it is assumed that the state shown in (b) of FIG. 2 is the initial state. If working fluid is supplied into the upper portion of the cylinder 201 through the expansion side working port 205, the piston 202 and the rod 203 are pushed downward due to the pressure of the working fluid, and the initial state is changed into an expansion state shown in (c) of FIG. 2.

On the contrary, if the working fluid is supplied into the lower portion of the cylinder 201 through the contraction side working port 206, the piston 202 and the rod 203 are pushed upward due to the pressure of the working fluid, and the initial state is changed into a contraction state shown in (a) of FIG. 2.

If the surface of the rod exposed outside the conventional hydraulic jack is corroded by flames or toxic gas or damaged by stone chips or scratches, the cylinder seal 208 inserted in the hole positioned on the bottom of the cylinder is damaged due to movement of the rod, and thus a gap is made between the inner surface of the hole positioned on the bottom of the cylinder and the surface of the rod coming in and out through the hole, and the working fluid leaks through the gap.

Particularly, the conventional hydraulic jack is formed to support lateral loads using only piston seals and cylinder seals respectively installed at two positions, and thus if the loads are applied in the radius direction (lateral direction) of the cylinder, e.g., if the lateral loads are applied to the cylinder due to modification of the platform supported by the hydraulic jack or a slope of the ground supporting the foot plate, metallic contacts occur between the rod and the cylinder and between the piston and the cylinder, respectively. Therefore, the cylinder seal is damaged, and the working fluid is leaked outside the cylinder through the damaged cylinder seal, and thus the hydraulic jack may lose its function.

It is undoubted that a hydraulic jack (or a hydraulic cylinder or a hydraulic mechanism) leaking the working fluid cannot properly support the load of a mounted structure, and an abruptly drooping phenomenon occurs while the hydraulic jack supports the load, and thus a serious danger may be incurred against safety of a worker.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a double cylinder type hydraulic mechanism suitable for being used in a poor working condition or environment in which damages on a rod coming in and out of a cylinder are expected. Even when a huge lateral load is applied due to modification of a mounted structure or operation of the hydraulic mechanism on a sloped ground, functions of the hydraulic mechanism (hydraulic jack or hydraulic cylinder) may not be lost although the seals are damaged by metallic contacts.

To accomplish the above object, according to one aspect of the present invention, there is provided a double cylinder type hydraulic mechanism, which can be used for an extended period of time since working fluid is not leaked although surfaces of working parts of the hydraulic mechanism exposed to external environments and performing vertical reciprocating actions are corroded or scratched by using the hydraulic mechanism for an extended period of time. Particularly, metallic contacts do not occur between the parts even in an operation condition where excessive lateral loads are applied, and thus the hydraulic mechanism may operate normally.

The present invention is characterized in that inner and outer cylinders are assembled to slide with each other, and contraction side and expansion side working ports are respectively formed on the flat top of the outer cylinder, and then two flow paths provided at an inner rod are respectively connected to the working ports, thereby removing pipe connection projections formed at the upper and lower portions of the cylinder surface, which are connected to external hydraulic lines.

According to another aspect of the present invention, a load supporting seal for supporting lateral loads and a seal for preventing leakage of working fluid and preventing foreign materials from being flowed inside the cylinder are respectively installed between the piston and the inner cylinder and between the inner cylinder and the outer cylinder.

Further specifically, the double cylinder type hydraulic mechanism according to the present invention includes an outer cylinder having an expansion side working port and a contraction side working port respectively formed on a top of the outer cylinder; an inner cylinder insertedly installed inside the outer cylinder so as to come in and out toward a bottom of the outer cylinder, an inner rod having two flow paths respectively connected to the expansion side working port and the contraction side working port, one end of which is fixed to an inner top surface of the outer cylinder, and the other end of which passes through a top of the inner cylinder and protrudes to be positioned inside the inner cylinder; and a piston combined with the other end of the inner rod to be positioned inside the inner cylinder and formed with a hole connected to the flow path of the inner rod connected to the expansion side working port.

In addition, the double cylinder type hydraulic mechanism according to the present invention preferably further includes an inner cylinder seal installed inside an upper hole of the inner cylinder in order to support lateral loads applied in a radius direction of the cylinder and prevent leakage of working fluid from the upper hole of the inner cylinder through which the other end of the inner rod slidingly penetrates; a piston seal installed on an outer surface of the piston in order to support the lateral loads applied in the radius direction of the cylinder and prevent leakage of the working fluid between the upper and lower spaces of the inner cylinder partitioned by the piston; and an outer cylinder seal installed on an inner surface of the outer cylinder in order to support the lateral loads applied in the radius direction of the cylinder and remove foreign materials attached on an outer surface of the inner cylinder.

In addition, as is typical, a foot plate supported on the ground is installed on the bottom of the inner cylinder of the double cylinder type hydraulic mechanism according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

(a), (b) and (c) of FIG. 1 are vertical cross-sectional views showing the configuration and working principles of a double cylinder type hydraulic mechanism according to the present invention.

(a), (b) and (c) of FIG. 2 are vertical cross-sectional views showing the configuration and working principles of a conventional hydraulic mechanism.

DESCRIPTION OF SYMBOLS

• • 101: Outer cylinder 102: Inner cylinder
  • 103: Inner rod 104: Piston
  • 105: Foot plate
  • 106: Expansion side working port
  • 107: Contraction side working port
  • 108: Inner cylinder seal
  • 109: Piston seal
  • 110: Outer cylinder seal
  • 201: Cylinder 202: Piston
  • 203: Rod 204: Foot plate
  • 205: Expansion side working port
  • 206: Contraction side working port
  • 207: Piston seal 208: Cylinder seal

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the configuration and working principles of a double cylinder type hydraulic mechanism according to the present invention will be described in detail, with reference to the accompanying drawings.

First, in relation to the drawings, FIG. 1 shows vertical cross-sectional views for describing the configuration and working principles of a double cylinder type hydraulic mechanism according to the present invention.

As shown in FIG. 1, the double cylinder type hydraulic mechanism according to the present invention includes an outer cylinder 101 having an expansion side working port 106 and a contraction side working port 107 respectively formed on the top; an inner cylinder 102 insertedly installed inside the outer cylinder 101 so as to come in and out toward the bottom of the outer cylinder 101; an inner rod 103 having two flow paths respectively connected to the expansion side working port 106 and the contraction side working port 107, one end of which is fixed to the inner top surface of the outer cylinder 101, and the other end of which passes through the top of the inner cylinder 102 and protrudes to be positioned inside the inner cylinder 102; a piston 104 combined with the other end of the inner rod 103 and formed with a hole connected to the flow path of the inner rod 103 connected to the expansion side working port 106; a foot plate 105 mounted on the bottom of the inner cylinder 102; an inner cylinder seal 108 installed inside an upper hole of the inner cylinder 102 in order to prevent leakage of working fluid from the upper hole of the inner cylinder 102 into which the other end of the inner rod 103 is slidingly inserted; a piston seal 109 insertedly attached to the outer surface of the piston 104 in order to prevent leakage of the working fluid between the upper and lower spaces of the inner cylinder 102 partitioned by the piston 104; and an outer cylinder seal 110 installed on the inner surface of the outer cylinder 101 in order to remove foreign materials attached on the outer surface of the inner cylinder 102. Here, the inner cylinder seal 108, the piston seal 109, and the outer cylinder seal 110 also support lateral loads applied in the radius direction of the inner and outer cylinders 101 and 102.

Meanwhile, an end of the flow path connected to the contraction side working port 107 of the outer cylinder 101 among the two flow paths formed at the inner rod 103 is open toward the upper space of the inner cylinder 102 partitioned by the piston 104.

Accordingly, if the working fluid is supplied to either the expansion side working port 106 or the contraction side working port 107, the inner cylinder 102 moves in the vertical direction of the outer cylinder 101 inside the outer cylinder 101.

Unlike a conventional hydraulic jack constructed to supply hydraulic fluid inside a cylinder through pipe connection projections respectively protruding at one side of the upper and lower portions of the cylinder surface, the double cylinder type hydraulic mechanism (or the hydraulic jack) according to the present invention is constructed to supply working fluid into the upper or lower space of the inner cylinder 102 through either the expansion side working port 106 or the contraction side working port 107 formed on the top of the outer cylinder 101.

As a result, since projections are not formed on the surface of the inner and outer cylinders 101 and 102 according to the present invention, when the hydraulic mechanism is installed in mounted equipment, effects of structural interference generated by hydraulic lines (or pipes) are greatly reduced.

Furthermore, in the double cylinder type hydraulic mechanism (or the hydraulic jack) according to the present invention, working fluid is supplied inside the inner cylinder 102 through the flow paths of the inner rod 103, and the inner cylinder 102 is exposed to outside. Unlike the conventional hydraulic jack in which the rod 203 directly contacting with the cylinder seal 208 is exposed to a poor working environment, although the surface of the inner cylinder 102 is corroded or scratched, the working fluid does not leak through the portions related to movements of the hydraulic mechanism since the surface of the inner cylinder 102 does not contact with the inner cylinder seal 108.

Furthermore, although seals installed at two positions sustain lateral loads in the conventional hydraulic jack, the lateral loads are sustained by seals installed at three or more positions in the double cylinder type hydraulic mechanism of the present invention, and thus the double cylinder type hydraulic mechanism according to the present invention may support further greater lateral loads although it has the same external sizes.

According to the double cylinder type hydraulic mechanism of the present invention constructed as described above, working fluid does not leak although the inner cylinder performing vertical reciprocating actions is exposed to external environments and the surface of the inner cylinder is corroded or scratched, and metallic contact is prevented by lateral load supporting actions of the inner cylinder seal, the piston seal, and the outer cylinder seal even in an operating condition of applying lateral loads, and thus the double cylinder type hydraulic mechanism may operate normally for an extended period of time.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

Claims

1. A double cylinder type hydraulic mechanism comprising:

an outer cylinder 101 having an expansion side working port 106 and a contraction side working port 107 respectively formed on a top of the outer cylinder;

an inner cylinder 102 insertedly installed inside the outer cylinder 101 so as to come in and out toward a bottom of the outer cylinder 101,

an inner rod 103 having two flow paths respectively connected to the expansion side working port 106 and the contraction side working port 107, one end of which is fixed to an inner top surface of the outer cylinder 101, and the other end of which passes through a top of the inner cylinder 102 and protrudes to be positioned inside the inner cylinder 102; and

a piston 104 combined with the other end of the inner rod 103 to be positioned inside the inner cylinder 102 and formed with a hole connected to the flow path of the inner rod 103 connected to the expansion side working port 106.

2. The mechanism according to claim 1, further comprising:

an inner cylinder seal 108 installed inside an upper hole of the inner cylinder 102 in order to support lateral loads applied in a radius direction of the cylinder and prevent leakage of working fluid from the upper hole of the inner cylinder 102 through which the other end of the inner rod 103 slidingly penetrates;

a piston seal 109 installed on an outer surface of the piston 104 in order to support the lateral loads applied in the radius direction of the cylinder and prevent leakage of the working fluid between the upper and lower spaces of the inner cylinder 102 partitioned by the piston 104; and

an outer cylinder seal 110 installed on an inner surface of the outer cylinder 101 in order to support the lateral loads applied in the radius direction of the cylinder and remove foreign materials attached on an outer surface of the inner cylinder 102.