KR20190007337A - Cushion structure of hydraulic cylinder provided with internally installed linear position sensor of piston - Google Patents

Abstract

Disclosed is a cushion structure of a hydraulic cylinder equipped with a piston position detection sensor, capable of allowing a cushioning function of the hydraulic cylinder device to be stably performed. According to the present invention, the cushion structure of the hydraulic cylinder to which a built-in linear sensor is applied includes: a tubular cylinder; a rod slidably installed in the cylinder; a piston fixed to one end of the rod and slidably installed on an inner peripheral surface of the cylinder; a head cover fixed to one end of the cylinder and having a main flow path for allowing a hydraulic fluid to flow between an outside and the piston; the built-in linear sensor installed on the piston to move integrally with the piston; a position detection sensor fixed to the head cover to detect a position of the piston according to the movement of the built-in linear sensor; a piston-integrated plunger unit extending from the piston while protruding toward the head cover more than a front end of the rod; a plunger reception groove formed in the head cover, and recessed to receive the piston-integrated plunger unit while the rod makes contact with the head cover; a cushion guide unit formed in a piston-integrated plunger unit reception unit such that an inner peripheral surface of the piston-integrated plunger unit slidably makes contact with the cushion guide unit; a cushion flow path formed in the head cover to allow the hydraulic fluid received in the piston-integrated plunger unit reception unit to bypass to the main flow path; and a check valve module disposed at a connection part between the cushion flow path and the main flow path, and having an orifice flow path.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cushion structure of a hydraulic cylinder,

The present invention relates to a hydraulic cylinder apparatus, and more particularly, to a head cover side cushion structure of a hydraulic cylinder provided with a sensor for detecting the position of a piston.

Generally, a hydraulic cylinder device is a mechanical device that generates a large force by using a small amount of oil using the Pascal principle. Hydraulic cylinder devices are widely used in various industrial fields. For example, hydraulic cylinder devices are widely used in forklifts. Forklifts are typical transport and handling equipment used to lift or lower heavy cargo or to transport such cargo to a desired location.

Such a hydraulic cylinder device generates a force by a piston moving by hydraulic pressure. A rod cover is installed at one end of the cylinder so that a rod moving integrally with the piston can be projected and withdrawn, and a head cover is installed at the other end of the cylinder. The head cover is generally provided with a cushion structure for preventing the piston from directly colliding with the head cover when the piston is compressed. As a typical example of the cushion structure, there is a cushion plunger that is provided to be able to flow at the other end of the rod.

On the other hand, a hydraulic cylinder having a piston position detecting sensor capable of detecting the position of the piston in real time so as to more precisely control the stroke of the rod of the hydraulic cylinder has been developed. An example of such a hydraulic cylinder is disclosed in Korean Patent Publication No. 2006-0126465. In the hydraulic cylinder disclosed in the above-mentioned patent, a sensor for detecting the position of the piston is fixed to the center of the head cover, and a magnet ring interacting with the sensor is moved in unison with the piston along the rod- Respectively.

However, the hydraulic cylinder having such a piston position detecting sensor is hardly provided with a cushion structure on the head cover side. Therefore, when the position of the piston sensed by the position detecting sensor approaches the head cover, the cushion function is performed by adjusting the flow of the hydraulic pressure. In such a structure, the cushioning function is implemented when the expansion and contraction of the piston is controlled automatically, but the cushioning function is not realized when the piston is manually expanded and contracted. If the cushion function is not properly implemented on the head cover side, there is a high possibility that the piston, the rod or the head cover is damaged, and thus the durability of the hydraulic cylinder is deteriorated.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic cylinder device in which a position detecting sensor of a piston is incorporated and a new cushion structure is designed so that a cushion function can be performed on a head cover side of the hydraulic cylinder apparatus, So that a stable cushioning function is performed.

To achieve the above object, a cushion structure of a hydraulic cylinder to which an embedded linear sensor according to an embodiment of the present invention is applied includes: a tubular cylinder;

A rod slidably installed in the cylinder;

A piston fixed to one end of the rod and slidably mounted on the inner circumferential surface of the cylinder;

A head cover fixed to one end of the cylinder and having a main flow path through which pressure oil flows between the outside and the piston;

A built-in linear sensor installed in the piston and moving integrally with the piston; And

And a position detection sensor fixed to the head cover and detecting the position of the piston in accordance with the movement of the built-in linear sensor, the cushion structure comprising:

A piston integral type plunger portion extending from the piston and protruding toward the head cover from a tip end portion of the rod;

A plunger receiving groove formed in the head cover and recessed to receive the piston integral type plunger portion in a state where the rod and the head cover are in contact with each other;

A cushion guide portion formed in the piston-integrated plunger portion accommodating portion such that an inner circumferential surface of the piston-integrated plunger portion is in sliding contact;

A cushion flow path formed in the head cover and bypassing the pressure oil accommodated in the piston integral type plunger portion accommodating portion to the main flow path; And

And a check valve module disposed at a connection portion between the cushion passage and the main passage and having an orifice passage.

A cushion ring groove portion formed concavely on an inner circumferential surface of the piston integral type plunger portion and extending along an inner circumferential surface of the piston integral type plunger portion; And

And a cushion ring accommodated in the cushion ring groove portion.

Wherein the check valve module comprises: a valve body having an orifice passage;

A support member disposed under the valve body;

A coil spring having one end supported by the valve body and the other end supported by the support member to press the valve body in a direction away from the support member;

A plug disposed under the support member and fixed to the head cover; And

And a plug o-ring coupled to the plug to prevent leakage of the flow path in which the check valve module is installed.

It is preferable that a plurality of the main flow paths are provided.

Wherein the built-in linear sensor is a magnet ring, the magnet ring is installed in a seating groove formed at the center of the tip of the rod,

And a stop ring which supports one end of the magnet ring and is coupled to the rod so as not to separate the magnet ring from the seating groove.

The position detecting sensor is connected to a sensor rod inserted in a groove formed in a central portion of the rod,

And the magnet ring is configured to slide along an outer circumferential surface of the sensor rod.

The cushion structure of the hydraulic cylinder to which the built-in linear sensor according to the present invention is applied is characterized in that a main passage is provided in the head cover so as not to interfere with the position detection sensor in the hydraulic cylinder in which the piston position detection sensor is disposed in the head cover, And a piston integral type plunger portion protruding further toward the head cover than the front end portion of the rod enters the plunger receiving groove formed in the head cover, and the pressure oil present in the plunger receiving groove passes through the cushion flow passage provided in the head cover, The cushioning action is performed while being discharged to the outside of the head cover through the orifice passage formed in the module. This provides the effect that the head cover side cushion function of the hydraulic cylinder equipped with the piston position detecting sensor on the head cover is always performed stably. That is, although the hydraulic cylinder equipped with the position detecting sensor of the piston is generally developed as unmanned equipment, such unmanned equipment often requires manual operation rather than fully automatic. In this case, the cushion structure of the hydraulic cylinder according to the present invention can prevent sudden collision between the rod and the head cover, thereby providing a stable cushioning action.

1 is a perspective view of a hydraulic cylinder having a cushion structure according to a preferred embodiment of the present invention.
2 is an exploded perspective view of the hydraulic cylinder shown in Fig.
3 is a longitudinal sectional view of the hydraulic cylinder shown in Fig.
4 is an enlarged view of the "A" portion shown in Fig.
5 is a cutaway perspective view of the check valve module shown in FIG.
FIG. 6 is a view showing the flow of pressure during compression of a rod in the drawing shown in FIG. 3; FIG.
FIG. 7 is a view showing the flow of pressure during cushion action in the view shown in FIG. 3; FIG.
FIG. 8 is a view showing the flow of pressure when the rod is stretched in the view shown in FIG. 3; FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a hydraulic cylinder having a cushion structure according to a preferred embodiment of the present invention. 2 is an exploded perspective view of the hydraulic cylinder shown in Fig. 3 is a longitudinal sectional view of the hydraulic cylinder shown in Fig. 4 is an enlarged view of the "A" portion shown in Fig. 5 is a cutaway perspective view of the check valve module shown in FIG. FIG. 6 is a view showing the flow of pressure during compression of a rod in the drawing shown in FIG. 3; FIG. FIG. 7 is a view showing the flow of pressure during cushion action in the view shown in FIG. 3; FIG. FIG. 8 is a view showing the flow of pressure when the rod is stretched in the view shown in FIG. 3; FIG.

1 to 8, a cushion structure 10 (hereinafter referred to as "cushion structure of a hydraulic cylinder") to which a built-in linear sensor according to a preferred embodiment of the present invention is applied includes a cylinder 20, 30, a piston 40, a head cover 50, a position detection sensor 100, a magnet ring 120, a piston integral type plunger portion 45, a plunger receiving groove 60, A guide portion 65, a cushion passage 56, and a check valve module 80.

The cylinder 20 is a tubular member provided with a hollow. The cylinder 20 may be manufactured by processing a steel sheet into a tubular shape, or may be manufactured by casting molten steel.

The rod 30 is slidably installed inside the cylinder. The rod 30 is a rod-shaped member. A sensor rod receiving groove 34 is provided at the center of the rod 30 in the thickness direction thereof to receive the sensor rod 110 described later in the longitudinal direction of the rod 30.

The sensor rod receiving groove 34 is opened toward the head cover 50 to be described later. At the entrance of the sensor rod receiving groove 34, a seating groove 32 for mounting the magnet ring 120 is provided. That is, the seating groove 32 is formed at the center of the distal end of the rod 30. The seating groove 32 is formed to have an inner diameter larger than the inner diameter of the sensor rod receiving groove 34.

The piston (40) is fixed to one end of the rod (30). The piston (40) is slidably mounted on the inner circumferential surface of the cylinder (20). The piston 40 is unexpectedly prevented from being unloaded from the rod 30 by the set screw. A rod cushion (41) is provided in front of the piston (40). The rod cushion 41 is a buffering element for preventing the piston 40 from physically colliding with the rod cover 22.

The head cover (50) is fixed to one end of the cylinder (20). The head cover 50 may be fixed to one end of the cylinder 20, for example, by welding. The head cover (50) is provided with a main flow path (52) through which pressurized oil flows between the outside and the piston (40). A plurality of the main flow paths 52 may be provided. The main passage 52 is configured to be opened or closed by the tip of the rod 30 and the piston 40. The head cover 50 is provided with a sensor fixing portion 53 to which a position detection sensor 100 described later is fixed. The sensor fixing part 53 is provided with a sensor wire passage (not shown) for connecting an electric wire connected to the position detecting sensor 100 to the outside. The sensor fixing portion 53 is disposed at the center of the head cover 50 in the thickness direction.

The head cover (50) has a plunger receiving groove (60) and a cushion flow path (56).

The plunger receiving groove 60 is formed in the head cover 50. The plunger receiving groove 60 is recessed to receive the plunger-integrated plunger portion 45, which will be described later, in a state where the rod 30 and the head cover 50 are in contact with each other. The plunger receiving groove 60 extends in the circumferential direction of the piston 40 so as to surround the sensor fixing portion 53 in an annular shape.

The cushion passage 56 is formed in the head cover 50. The cushion passage 56 is formed independently of the main passage 52. The cushion passage 56 is formed at a position where the distal end of the rod 30 is not closed even when the tip of the rod 30 is in contact with the head cover 50. The cushion flow path 56 is configured to bypass pressure fluid received in the plunger receiving groove 60 to the main flow path 52. The cushion passage 56 is connected to the plunger receiving groove 60. The cushion flow path 56 is connected to the main flow path 52.

The position detection sensor 100 is fixed to the head cover 50. [ More specifically, the position detection sensor 100 is fixed to the sensor fixing portion 53. [ The position detection sensor 100 is connected to the sensor rod 110. The sensor rod 110 is made of a metal rod or a magnet so that the magnetic field is changed according to a change in the position of the magnet ring 120, which will be described later. The sensor rod 110 is formed at the center of the rod 30 in the radial direction and accommodated in the sensor rod receiving groove 34 extending in the longitudinal direction of the rod 30. The position detection sensor 100 and the sensor rod 110 are fixed to the head cover 50 and therefore do not move.

The position detection sensor 100 is a sensor that detects the position of the piston 40 by sensing a change in magnetic force due to the movement of the magnet ring 120, which will be described later.

The magnet ring (120) is installed in the piston (40). More specifically, the magnet ring 120 is installed in the seating groove 32. The magnet ring 120 is in close contact with the inner wall of the seating groove 32. One end of the magnet ring 120 is in close contact with the stop ring 125. The stop ring 125 is a member for supporting one end of the magnet ring 120 to prevent the magnet ring 120 from being separated from the seating groove 32. The stop ring 125 is resiliently fixed to the rod 30. The stop ring 125 may be, for example, a member of a "C" shape. The magnet ring 120 moves integrally with the piston 40. The magnet ring 120 may be slidably moved along the outer circumferential surface of the sensor rod 110.

In this embodiment, the magnet ring 120 constitutes a built-in linear sensor system that cooperates with the position detection sensor 100 to detect the position of the piston 40. It is apparent that the built-in linear sensor system may adopt other known sensors such as a wire sensor in addition to the magnet ring 120 described above. In the built-in linear sensor system, a sensor is disposed to detect the position of the piston 40 in the hydraulic cylinder.

The piston-integrated plunger portion 45 protrudes from the distal end of the piston 40. The piston integral type plunger portion 45 is formed integrally with the piston 40. The piston integral type plunger portion 45 is configured to protrude further toward the head cover 50 than the distal end portion of the rod 30. A cushion ring groove portion 47 is provided on the inner circumferential surface of the piston integral type plunger portion 45. The cushion ring groove portion 47 is formed concavely in the inner peripheral surface of the piston integral type plunger portion 45. The cushion ring groove portion 47 extends around the inner circumferential surface of the piston integral type plunger portion 45. A cushion ring (48) is accommodated in the cushion ring groove portion (47). The cushion ring 48 seals the cushion guide portion 65 to be described later so that the pressure oil can not flow directly from the plunger receiving groove 60 to the main flow path 52 during cushioning operation.

The cushion guide portion (65) is formed in the plunger receiving groove (60). The cushion guide portion 65 is formed on the inner wall of the plunger receiving groove 60 so that the inner circumferential surface of the piston integral type plunger portion 45 is in sliding contact. The cushion ring (48) prevents the generation of a fine flow path between the piston integral type plunger portion (45) and the cushion guide portion (65).

The piston integral type plunger portion 45 flows in the radial direction of the rod 30 when the piston integral type plunger portion 45 enters the plunger receiving groove 60 And to guide them not to do so. Accordingly, the cushion guide portion 65 is disposed in sliding contact with the inner circumferential surface of the plunger portion 45 integrated with the piston.

The check valve module 80 is disposed at a connection portion between the cushion flow path 56 and the main flow path 52. The check valve module 80 is provided with an orifice passage 83. The check valve module 80 performs cushioning action through the orifice passage 83. Meanwhile, the check valve module 80 serves as a flow path for supplying the pressure oil to the piston 40 in the course of the extension of the rod 30.

The check valve module 80 includes a valve body 82, a support member 84, a coil spring 86, a plug 87, and a plug O-ring 89.

The valve body 82 is provided with an orifice passage 83. The valve body 82 is disposed movably within a predetermined range with respect to the cushion passage 56 or the main passage 52. And an engagement protrusion for restricting movement of the valve body 82 is provided on the valve body 82.

The support member 84 is disposed below the valve body 82. The support member 84 may be a plate-shaped member.

The coil spring 86 may be a compression coil spring. One end of the coil spring 86 is supported by the valve body 82. The other end of the coil spring 86 is supported by the support member 84. The coil spring 86 urges the valve body 82 in a direction away from the support member 84. [

The plug 87 is disposed below the support member 84. The plug 87 can be fixed to the head cover 50, for example, by interference fit or by screwing. The plug 87 serves to fix the position of the support member 84.

The plug O-ring 89 is coupled to the plug 87. The plug O-ring 89 is coupled to the outer circumferential surface of the plug 87. The plug o-ring 89 prevents leakage of the main flow path 52 in which the check valve module 80 is installed.

The head cover 50 may be provided with an inner ring 90. The inner ring 90 is a ring-shaped member. The inner ring 90 is fixed to the inner circumferential surface of the head cover 50 and the inner circumferential surface of the cylinder 20 by welding. A flow preventing protrusion 92 may be provided on the outer circumferential surface of the inner ring 90. The flow preventing protrusion 92 protrudes outward from the outer peripheral surface of the inner ring 90. The flow preventing protrusion 92 extends in the outer circumferential direction of the inner ring 90. The flow preventive protrusion 92 is arranged to be received in the head cover 50 or the groove formed in the inner circumferential surface of the cylinder 20. The flow preventing protrusion 92 serves to prevent the inner ring 90 from flowing in the longitudinal direction of the cylinder 20 unexpectedly. The inner ring 90 serves to reinforce a connection portion between the cylinder 20 and the head cover 50.

Hereinafter, the operation and effect of the cushion structure 10 of the hydraulic cylinder including the above-described components will be described in detail by taking as an example the process of compressing the rod 30 from the extended state.

First, the description starts from the state shown in Fig. A pressure oil is supplied into the cylinder (20) from the rod cover (22) side of the hydraulic cylinder (20). The piston 40 is moved toward the head cover 50 by the pressure oil supplied from the rod cover 22 side. The rod 30 moves integrally with the piston 40 so that the rod 30 moves toward the head cover 50 along the piston 40. In this process, the magnet ring 120 moves integrally with the rod 30. The magnet ring 120 slides along the outer circumferential surface of the sensor rod 110. As the magnet ring 120 moves, the magnetic field around the sensor rod 110 changes. The change of the magnetic field of the sensor rod 110 is detected by the position detection sensor 100 and the position of the piston 40 is detected in real time. The piston 40 comes close to the head cover 50. The piston integral type plunger portion 45 enters the plunger receiving groove 60 to start the cushioning action. The inner circumferential surface of the piston integral type plunger portion 45 is slidingly contacted along the cushion guide portion 65 so that the pressure fluid existing in the plunger receiving groove 60 can not be discharged to the outside through the main flow path 52. As a result, a pressure opposite to the advance of the piston 40 is generated. Accordingly, the moving speed of the piston (40) and the rod (30) is lowered. The pressure oil present in the plunger receiving groove 60 reaches the check valve module 80 through the cushion flow channel 56. Only a small amount of pressure is discharged to the outside of the head cover 50 through the main flow path 52 through the orifice passage 83 provided in the check valve module 80. The pressure oil present in the space formed between the inner circumferential surface of the piston integral type plunger portion 45 and the distal end portion of the rod 30 and the sensor fixing portion 53 passes through the main flow path 52 without resistance to the head cover 50, As shown in FIG.

When the tip of the rod 30 comes into mechanical contact with the head cover 50, the rod 30 is completely compressed and is no longer compressed. Through the above process, the rod 30 performs a cushioning operation in the compression process.

The process of extending the rod 30 will now be described.

Pressure oil is supplied to the head cover 50 from the outside through the main flow path 52 provided in the head cover 50. [ The pressurized oil supplied to the head cover 50 presses the leading end of the rod 30 through the main flow path 52. In addition, the check valve module 80 is supplied with pressurized fluid so that the valve body 82 overcomes the elastic restoring force of the coil spring 86 and descends to open the check valve module 80. The pressure oil supplied through the check valve module 80 flows into the plunger receiving groove 60 through the cushion flow path 56. The pressurized oil simultaneously presses the distal end of the rod 30 and the piston 40, thereby generating a large elongation pressure. The rod 30 is stretched away from the head cover 50.

As described above, the cushion structure of the hydraulic cylinder to which the built-in linear sensor according to the present invention is applied is characterized in that a main passage is provided in the head cover so as not to interfere with the position detection sensor in the hydraulic cylinder in which the piston position detection sensor is disposed in the head cover, And a plunger integral with the plunger integrally formed with the plunger integrally protruding toward the head cover rather than the front end of the rod enters the plunger receiving groove formed in the head cover so that the pressure oil present in the plunger receiving groove flows through the cushion flow passage And is discharged to the outside of the head cover through the orifice passage formed in the check valve module, thereby performing the cushioning action. This provides the effect that the head cover side cushion function of the hydraulic cylinder equipped with the piston position detecting sensor on the head cover is always performed stably. That is, although the hydraulic cylinder equipped with the position detecting sensor of the piston is generally developed as unmanned equipment, such unmanned equipment often requires manual operation rather than fully automatic. In this case, the cushion structure of the hydraulic cylinder according to the present invention can prevent sudden collision between the rod and the head cover, thereby providing a stable cushioning action.

While the present invention has been described with reference to the preferred embodiments, it is to be understood that the invention is not to be limited by the example, and various changes and modifications may be made without departing from the spirit and scope of the invention.

10: Cushion structure of hydraulic cylinder
20: Cylinder
22: Road cover
30: Load
32: seat groove
34: sensor load receiving groove
40: Piston
45: piston-integrated plunger portion
47: Cushion ring groove portion
48: Cushion ring
50: Head cover
52: Main flow path
53: Sensor fixing section
56: Cushion Euro
60: plunger receiving groove
65: Cushion guide portion
80: Check valve module
82: Valve body
83: Orifice Euro
84: Support member
86: coil spring
87: Plug
89: Plug O-ring
90: Inner ring
92: flow prevention protrusion
100: Position detection sensor
110: Sensor load
120: Magnet ring
125: Stop ring

Claims (6)

A tubular cylinder;
A rod slidably installed in the cylinder;
A piston fixed to one end of the rod and slidably mounted on the inner circumferential surface of the cylinder;
A head cover fixed to one end of the cylinder and having a main flow path through which pressure oil flows between the outside and the piston;
A built-in linear sensor installed in the piston and moving integrally with the piston; And
And a position detection sensor fixed to the head cover and detecting the position of the piston in accordance with the movement of the built-in linear sensor, the cushion structure comprising:
A piston integral type plunger portion extending from the piston and protruding toward the head cover from a tip end portion of the rod;
A plunger receiving groove formed in the head cover and recessed to receive the piston integral type plunger portion in a state where the rod and the head cover are in contact with each other;
A cushion guide portion formed in the piston-integrated plunger portion accommodating portion such that an inner circumferential surface of the piston-integrated plunger portion is in sliding contact;
A cushion flow path formed in the head cover and bypassing the pressure oil accommodated in the piston integral type plunger portion accommodating portion to the main flow path; And
And a check valve module disposed at a connection portion between the cushion passage and the main passage and having an orifice passage. The method according to claim 1,
A cushion ring groove portion formed concavely on an inner circumferential surface of the piston integral type plunger portion and extending along an inner circumferential surface of the piston integral type plunger portion; And
And a cushion ring accommodated in the cushion ring groove portion. The cushion structure of the hydraulic cylinder to which the built-in linear sensor is applied. The method according to claim 1,
Wherein the check valve module comprises: a valve body having an orifice passage;
A support member disposed under the valve body;
A coil spring having one end supported by the valve body and the other end supported by the support member to press the valve body in a direction away from the support member;
A plug disposed under the support member and fixed to the head cover; And
And a plug o-ring coupled to the plug to prevent oil leakage of the flow passage in which the check valve module is installed. The method according to claim 1,
Wherein a plurality of the main flow paths are provided. The method according to claim 1,
Wherein the built-in linear sensor is a magnet ring, the magnet ring is installed in a seating groove formed at the center of the tip of the rod,
And a stop ring that supports one end of the magnet ring and is coupled to the rod so that the magnet ring is not separated from the seating groove. The method according to claim 1,
The position detecting sensor is connected to a sensor rod inserted in a groove formed in a central portion of the rod,
Wherein the magnet ring is configured to slide along an outer circumferential surface of the sensor rod.

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