JP5040338B2 - Sealing device and hydraulic cylinder - Google Patents

Description

  The present invention relates to a sealing device and a hydraulic cylinder that prevent gas leakage to a first sealed region in which liquid is sealed and prevent liquid leakage to a second sealed region in which gas is sealed.

  For example, some hydraulic cylinders used in breakers have a sealed region (first sealed region) in which a liquid such as oil is sealed and a sealed region (second sealed region) in which a gas such as nitrogen gas is sealed. . Such a hydraulic cylinder is provided with a sealing device for simultaneously sealing the first sealing region and the second sealing region. A conventional example of such a sealing device will be described with reference to FIGS. FIG. 7 is a schematic cross-sectional view of a sealing device according to Conventional Example 1. FIG. 8 is a schematic cross-sectional view of a sealing device according to Conventional Example 2.

  In order to prevent the liquid leakage from the first sealing region to the second sealing region and the gas leakage from the second sealing region to the first sealing region at the same time, the first sealing region side and the second sealing region side Suitably each has a sealing lip. Therefore, in order to seal two sealing regions at the same time, as shown in FIGS. 7 and 8, an X ring having a substantially X-shaped cross section is generally used.

  Sealing devices 100 and 200 shown in FIGS. 7 and 8, respectively, are provided in a hydraulic cylinder used in a breaker, and include an outer peripheral surface of a piston 132 that reciprocates and an inner peripheral surface of a shaft hole formed in the cylinder 131. It arrange | positions in the cyclic | annular clearance gap between. These sealing devices 100 and 200 simultaneously seal the first sealing region O sealed with oil and the second sealing region G sealed with nitrogen gas.

  The sealing device 100 illustrated in FIG. 7 includes a first seal lip 101 provided on the first sealing region O side and a second seal lip 102 provided on the second sealing region G side. Each of the first seal lip 101 and the second seal lip 102 has a rounded shape (curved surface shape (R shape)).

  The sealing device 200 shown in FIG. 8 also includes a first seal lip 201 provided on the first sealing region O side and a second seal lip 202 provided on the second sealing region G side. Each of the first seal lip 201 and the second seal lip 202 is configured to have an angular shape (edge shape (pointed shape)) at the tip of the lip.

  Here, the idea that the sealing mechanism in the reciprocating sealing device is generally based on the thickness of the fluid to be sealed formed in the sliding portion. For example, the case of a general reciprocating sealing device that is disposed in an annular gap between a relatively reciprocating shaft and a housing and prevents oil from leaking to the atmosphere side will be described as an example. In this case, when the sealing device moves to the atmosphere side with respect to the shaft (pulling step), the oil film formed on the portion where the sealing device slides on the shaft surface is closer to the sealing region side with respect to the shaft. In the case of moving to (pushing process), the oil film is formed to be thicker than the oil film formed on the part. With such a configuration, a suction phenomenon in which oil is sucked into the sealed fluid side occurs, so that oil can be prevented from leaking to the atmosphere side.

On the other hand, in the case of the sealing devices 100 and 200 described above, a film of a fluid to be sealed that can be formed as a sliding portion when the sealing devices 100 and 200 move toward the first sealing region O with respect to the piston 132. And the thickness of the film of the fluid to be sealed that can be formed in the sliding portion when moved to the second sealing region G side are set to be theoretically equal.

  This is because the concept of the sealing mechanism in the reciprocating seal is the same regardless of whether the fluid to be sealed is liquid or gas, so that oil leaks into the second sealed region G and nitrogen into the first sealed region O. In order to prevent gas leakage at the same time, it is based on the design concept that the suction phenomenon should not occur on either side. In the above-described sealing devices 100 and 200, the suction phenomenon does not occur on either side by being symmetrical with respect to the center C of the axial width.

  However, in practice, oil leakage has occurred on the second sealed region G side. First, when the sealing devices 100 and 200 reciprocate with respect to the piston 132, even if the thickness of the oil film that can be made in the forward path and the thickness of the oil film that can be made in the return path are theoretically equal, In other words, due to some influence (disturbance such as eccentricity and various dimensional errors), it is impossible to always make the thickness of the oil film as designed. Second, since an oil film is formed in the portion where the lip tip and the piston 132 slide, it is considered that gas (nitrogen gas) hardly leaks into the first sealed region O. It is done.

  Further, in the sealing devices 100 and 200 as described above, in general, a plurality of minute annular protrusions are provided at the tip of the lip in order to improve slidability. FIG. 9 is a schematic cross-sectional view showing the vicinity of the tip of a lip in a conventional sealing device. As shown in the drawing, a plurality of minute annular protrusions 121a and 122a are formed on the inclined surface on the second sealing region G side of the first seal lip 121 and on the inclined surface on the first sealing region O side of the second seal lip 122, respectively. Is provided. Since these annular protrusions 121a and 122a are provided on the sliding surface and oil can be held in the gap formed between the protrusions, it is possible to improve the slidability.

  Here, these annular protrusions 121a and 122a are designed so that the fluid to be sealed is drawn to the sealing region side based on the sealing mechanism in the reciprocating sealing device. That is, the annular protrusion 121a is designed so that the fluid to be sealed is drawn into the first sealing region O side, and the annular protrusion 122a is designed so that the fluid to be sealed is drawn into the second sealing region G side.

  For this reason, it is desirable that the oil is drawn into the first sealing region O by the annular protrusion 121a, but the result is that the oil is sent out to the second sealing region G by the annular protrusion 122a. Thereby, the oil leakage to the 2nd sealing area G was promoted.

In addition, as a related technique, there exists what was disclosed by patent documents 1-3.
Japanese Utility Model Publication No. 1-174677 Japanese Patent Laid-Open No. 9-14451 International Publication Number WO2002 / 099320

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sealing device that can prevent gas leakage to a first sealed region sealed with liquid and more reliably prevent liquid leak to a second sealed region sealed with gas. And providing a hydraulic cylinder.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing device of the present invention is
A sealing device disposed in an annular gap between two members that reciprocally move relatively,
A first seal lip which is provided on the side of the first sealed region where the liquid is sealed and which slides on the surface of one of the two members;
A second seal lip that is provided on the side of the second sealed region where the gas is sealed and slides relative to the surface of the one member,
In a sealing device for preventing gas leakage to the first sealed region and preventing liquid leakage to the second sealed region,
The shape of the lip tip of the first seal lip and the shape of the lip tip of the second seal lip are
When the first seal lip slides with respect to the surface of the one member, the thickness of the film formed by the liquid formed on the sliding portion is determined when the second seal lip slides with respect to the surface of the one member. On the other hand, the lip tip of the first seal lip has an angular shape so as to be thinner than the thickness of the liquid film formed on the sliding portion, whereas the lip tip of the second seal lip is rounded. It is characterized by comprising a different shape .
Further, the sealing device of another invention is
A sealing device disposed in an annular gap between two members that reciprocally move relatively,
A first seal lip which is provided on the side of the first sealed region where the liquid is sealed and which slides on the surface of one of the two members;
A second seal lip that is provided on the side of the second sealed region where the gas is sealed and slides relative to the surface of the one member,
In a sealing device for preventing gas leakage to the first sealed region and preventing liquid leakage to the second sealed region,
The shape of the lip tip of the first seal lip and the shape of the lip tip of the second seal lip are
When the first seal lip slides with respect to the surface of the one member, the thickness of the film formed by the liquid formed on the sliding portion is determined when the second seal lip slides with respect to the surface of the one member. The lip tip of the first seal lip and the lip tip of the second seal lip are both rounded and have a curvature so as to be thinner than the thickness of the film formed by the liquid formed on the sliding portion. The radius is configured to be smaller at the tip of the first seal lip.
It is a sign.

  According to the present invention, since the shape of the lip tip of the first seal lip and the shape of the lip tip of the second seal lip are configured as described above, a suction phenomenon in which liquid is sucked into the first sealed region side occurs. . Thereby, the liquid leak to a 2nd sealing area | region can be prevented more reliably. Since a liquid film is formed between the lip tip of the first seal lip and the one member surface and between the lip tip of the second seal lip and the one member surface, the gas is sealed in the first seal lip. It does not leak into the area.

A plurality of annular protrusions are provided on both the inclined surface on the second sealing region side of the first seal lip and the inclined surface on the first sealing region side of the second seal lip,
These annular projections are formed by inclined surfaces on both the first sealing region side and the second sealing region side, and the one member is in a state in which these annular projections slide with respect to the surface of the one member. It is preferable that the inclination angle of the inclined surface on the first sealing region side with respect to the surface is larger than the inclination angle of the inclined surface on the second sealing region side.

  In this way, since both the first seal lip and the second seal lip act to move the liquid to the first sealed region side, liquid leakage to the second sealed region can be prevented more reliably. can do.

The hydraulic cylinder of the present invention is
A cylinder having a shaft hole;
In a hydraulic cylinder comprising a piston inserted into the shaft hole,
In the cylinder, a first sealed area sealed with oil and a second sealed area sealed with nitrogen gas are formed,
A first seal lip is provided on the first sealing region side and a second seal lip is provided on the second sealing region side with respect to the annular gap between the inner peripheral surface of the shaft hole and the outer peripheral surface of the piston. The above-mentioned sealing device is arranged.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, it is possible to prevent gas leakage to the first sealed region where the liquid is sealed and more reliably prevent liquid leak to the second sealed region where the gas is sealed. Can do.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
A sealing device and a hydraulic cylinder according to an embodiment of the present invention will be described with reference to FIGS.

<Hydraulic cylinder>
With reference to FIG. 1, the structure of the hydraulic cylinder which concerns on the Example of this invention is demonstrated. Here, a case where a hydraulic cylinder is applied to a breaker will be described as an example. FIG. 1 is a schematic cross-sectional view of a breaker to which a hydraulic cylinder according to an embodiment of the present invention is applied.

  The breaker 30 includes a cylindrical cylinder 31 having a shaft hole, and a piston 32 inserted into the shaft hole of the cylinder 31 so as to have a clearance with respect to the inner peripheral surface of the shaft hole. A chisel (rod) 33 for pulverizing concrete or rock is provided at the tip of the piston 32.

  A cylindrical front head 34 is coaxially fixed to the tip end side of the cylinder 31. A chisel 33 is provided inside the front head 34 so as to be able to reciprocate. A thrust ring and a thrust bush are incorporated in the front head 34 in order to receive an impact from the chisel 33. A bottomed cylindrical back head 35 is coaxially fixed to the rear end side of the cylinder 31. The back head 35 incorporates a hydraulic outlet and a gas intake valve, and is filled with nitrogen gas (hereinafter, a region where the nitrogen gas is sealed is referred to as a second sealed region G). Called).

  In addition, the breaker 30 performs pressure compensation and prevention of pulsation of a control valve 36 for controlling the reciprocating movement of the piston 32 and a hydraulic circuit provided in the cylinder 31, and is filled with high-pressure nitrogen gas. An accumulator 37 is also provided.

  In order to seal the annular gap between the shaft hole provided in the cylinder 31 and the piston 32, a first sealing system 10 and a second sealing system 20 are provided on the rear end side and the front end side, respectively. . In FIG. 1, the first sealing system 10 and the second sealing system 20 are simply shown. And between these 1st sealing system 10 and the 2nd sealing system 20, oil is enclosed (henceforth, the field where this oil is sealed is called the 1st sealed field O). The first sealing system 10 plays a role of preventing leakage of the above-described nitrogen gas while preventing leakage of the oil. The second sealing system 20 plays a role of preventing oil leakage and preventing dust from entering from the outside.

In the breaker 30 configured as described above, the piston 3 is driven by hydraulic pressure and gas pressure.
The pile-shaped chisel 33 is reciprocated at a high speed in the axial direction together with 2 and the tip of the chisel 33 is hit against the destruction target (concrete, bedrock, etc.), so that the destruction target can be crushed. Note that the piston 32 and the chisel 33 can be moved toward the destruction target at a high speed (for example, 10 m / s) by compressing the gas by hydraulic pressure and using the repulsive force of the gas.

<First sealing system>
The first sealing system 10 will be described with reference to FIG. FIG. 2 is a partially enlarged sectional view (an enlarged sectional view around the first sealing system) of the hydraulic cylinder according to the embodiment of the present invention.

  The first sealing system 10 includes a sealing unit 40 provided on the first sealing region O side and a sealing device 50 provided on the second sealing region G side. A first annular groove 31 a and a second annular groove 31 b are formed on the inner peripheral surface of the shaft hole of the cylinder 31. A sealing unit 40 is provided in the first annular groove 31a, and a sealing device 50 is provided in the second annular groove 31b.

  The sealing unit 40 includes a resin ring 41 slidably provided on the outer peripheral surface of the piston 32, and a rubber ring 42 fitted on the outer periphery of the resin ring 41. The rubber ring 42 is in close contact with the groove bottom of the first annular groove 31 a and presses the resin ring 41 toward the outer peripheral surface of the piston 32 by its own elastic repulsive force. The sealing unit 40 configured in this manner mainly exhibits a function of buffering a hydraulic pressure that is a high pressure.

  The sealing device 50 is a seal ring made of a rubber-like elastic body, and leaks oil from the first sealing region O to the second sealing region G and nitrogen gas from the second sealing region G to the first sealing region O. This is to prevent leakage of the water at the same time. The sealing device 50 will be described in detail below.

<Sealing device>
In particular, a sealing device 50 according to an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 3 is a schematic cross-sectional view showing a mounting state of the sealing device according to the embodiment of the present invention. FIG. 4 is a partially enlarged cross-sectional view (enlarged cross-sectional view of the sliding portion) of the sealing device according to the embodiment of the present invention. FIG. 5 is an enlarged view of a part of FIG. 4 (the sliding portion of the first seal lip). FIG. 6 is an enlarged view of a part of FIG. 4 (sliding portion of the second seal lip).

  The sealing device 50 includes a first seal lip 51 and a second seal lip 52 that slide against the outer peripheral surface of the piston 32, and an inner wall surface of a second annular groove 31b provided on the inner peripheral surface of the shaft hole of the cylinder 31. A third seal lip 53 and a fourth seal lip 54 that are in close contact with each other. As described above, the sealing device 50 is a so-called X-ring having four seal lips and having a substantially X-shaped cross section.

  The first seal lip 51 is provided on the first sealing region O side, and the second seal lip 52 is provided on the second sealing region G side. The lip tip of the first seal lip 51 is formed in an angular shape (edge shape (pointed shape)). On the other hand, the lip tip of the second seal lip 52 is formed in a rounded shape (curved surface shape (R shape)).

  Further, as shown in FIG. 4, a plurality of minute annular protrusions are respectively formed on the inclined surface of the first seal lip 51 on the second sealing region G side and the inclined surface of the second seal lip 52 on the first sealing region O side. 51a and 52a are provided. The annular protrusions 51 a and 52 a are provided concentrically with the piston 32.

  These annular protrusions 51 a and 52 a are configured by inclined surfaces on both the first sealing area O side and the second sealing area G side, and these annular protrusions 51 a and 52 a slide on the outer peripheral surface of the piston 32. In the moved state, the inclination angle of the inclined surface on the first sealing region O side with respect to the outer peripheral surface is configured to be larger than the inclination angle of the inclined surface on the second sealing region G side. That is, as shown in FIG. 5, when the inclination angle of the inclined surface on the first sealing region O side in the annular protrusion 51a is α1, and the inclination angle of the inclined surface on the second sealing region G side is β1, α1> It is configured to be β1. As shown in FIG. 6, when the inclination angle of the inclined surface on the first sealing region O side in the annular protrusion 52a is α2, and the inclination angle of the inclined surface on the second sealing region G side is β2, α2> It is configured to be β2. In the present embodiment, α1 = α2 and β1 = β2 are set so as to satisfy the relationship.

  As described above, the plurality of annular protrusions 51a provided at the sliding portion of the lip tip of the first seal lip 51 and the plurality of annular protrusions 52a provided at the sliding portion of the lip tip of the second seal lip 52 are all. When the piston 32 is reciprocated between the outer peripheral surface of the piston 32, a suction phenomenon in which the fluid to be sealed is sucked into the first sealed region O side occurs. The reason why the suction phenomenon occurs is as described in the background art regarding the sealing mechanism in the reciprocating sealing device.

<Excellent point of this embodiment (function of sealing device)>
In the sealing device 50 according to the present embodiment, the thickness of the oil film formed on the sliding portion when the first seal lip 51 slides with respect to the surface of the piston 32 is the same as that of the second seal lip 52 of the piston 32. There is a feature that the thickness of the oil film formed on the sliding portion becomes thinner when sliding with respect to the surface.

  As described above, in the sealing device 50 according to the present embodiment, the lip tip of the first seal lip 51 is formed in an angular shape, whereas the lip tip of the second seal lip 52 is rounded. This is due to the fact that it has a tangled shape.

  Therefore, when the sealing device 50 moves to the first sealing region O side with respect to the piston 32 (moves in the direction of arrow X in FIG. 3), the thickness of the oil film formed by the sealing device 50 on the surface of the piston 32 However, when the sealing device 50 moves to the second sealing region G side with respect to the piston 32 (moving in the direction of arrow Y in FIG. 3), the thickness of the oil film formed by the sealing device 50 on the surface of the piston 32 is larger. getting thin.

  As a result, a suction phenomenon occurs in which oil is sucked into the first sealed region O side. Therefore, oil leakage to the second sealing region G can be prevented more reliably.

  Here, since a suction phenomenon occurs in which the fluid to be sealed is sucked into the first sealed region O side, it seems that the nitrogen gas on the second sealed region G side leaks into the first sealed region O at first glance. . However, in practice, the lip tip of the first seal lip 51 and the surface of the piston 32 slide, and the lip tip of the second seal lip 52 and the surface of the piston 32 also slide. An oil film is formed on the sliding portion. Therefore, nitrogen gas does not leak into the first sealed region O.

  In the present embodiment, a plurality of annular protrusions 51 a are provided at the sliding portion of the lip tip of the first seal lip 51, and a plurality of annular protrusions 52 a are provided at the sliding portion of the lip tip of the second seal lip 52. Is provided. Therefore, oil can be held in the gap formed between the protrusions, so that slidability can be improved.

The annular protrusions 51a and 52a are configured such that when the reciprocating movement between the annular protrusions 51a and 52a and the outer peripheral surface of the piston 32 is performed, a suction phenomenon in which the fluid to be sealed is sucked into the first sealing region O side occurs. . Accordingly, since both the first seal lip 51 and the second seal lip 52 act to move the oil to the first sealed region O, liquid leakage to the second sealed region G can be prevented more reliably. can do.

<Others>
In the above embodiment, the lip tip of the first seal lip 51 is configured to have an angular shape, whereas the lip tip of the second seal lip 52 is configured to have a rounded shape. .

  However, the point is that the thickness of the oil film formed on the sliding portion when the first seal lip 51 slides on the surface of the piston 32 is such that the second seal lip 52 slides on the surface of the piston 32. In this case, the thickness of the oil film formed on the sliding portion may be made thinner.

  In order to achieve this, for example, the lip tip of the first seal lip 51 and the lip tip of the second seal lip 52 are both rounded and the radius of curvature of the first seal lip 51 is greater. It may be made smaller. In this case, it is preferable that the radius of curvature (R) of the lip tip of the second seal lip 52 is increased as much as the space of the second annular groove 31b permits.

  In addition, it can be considered that the thickness of the oil film is different by giving a difference in the compression amount (tightening allowance) of the lip. However, when there is a difference in the compression amount of the lip, a difference in the surface pressure (contact pressure) at the tip of the lip appears, but a difference in pressure gradient hardly occurs, so that there is not much difference in the thickness of the oil film. Therefore, it is not practical to make the oil film thicknesses different as described above by making a difference in the compression amount of the lip.

FIG. 1 is a schematic cross-sectional view of a breaker to which a hydraulic cylinder according to an embodiment of the present invention is applied. FIG. 2 is a partially enlarged sectional view of the hydraulic cylinder according to the embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a mounting state of the sealing device according to the embodiment of the present invention. FIG. 4 is a partially enlarged cross-sectional view of the sealing device according to the embodiment of the present invention. FIG. 5 is an enlarged view of a part of FIG. FIG. 6 is an enlarged view of a part of FIG. FIG. 7 is a schematic cross-sectional view of a sealing device according to Conventional Example 1. FIG. 8 is a schematic cross-sectional view of a sealing device according to Conventional Example 2. FIG. 9 is a schematic cross-sectional view showing the vicinity of the tip of a lip in a conventional sealing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st sealing system 20 2nd sealing system 30 Breaker 31 Cylinder 31a 1st annular groove 31b 2nd annular groove 32 Piston 33 Chisel 34 Front head 35 Back head 36 Control valve 37 Accumulator 40 Sealing unit 41 Resin ring 42 Rubber ring 50 sealing device 51 first seal lip 51a annular projection 52 second seal lip 52a annular projection 53 third seal lip 54 fourth seal lip O first sealing region G second sealing region

Claims (4)

A sealing device disposed in an annular gap between two members that reciprocally move relatively,
A first seal lip which is provided on the side of the first sealed region where the liquid is sealed and which slides on the surface of one of the two members;
A second seal lip that is provided on the side of the second sealed region where the gas is sealed and slides relative to the surface of the one member,
In a sealing device for preventing gas leakage to the first sealed region and preventing liquid leakage to the second sealed region,
The shape of the lip tip of the first seal lip and the shape of the lip tip of the second seal lip are
When the first seal lip slides with respect to the surface of the one member, the thickness of the film formed by the liquid formed on the sliding portion is determined when the second seal lip slides with respect to the surface of the one member. On the other hand, the lip tip of the first seal lip has an angular shape so as to be thinner than the thickness of the liquid film formed on the sliding portion, whereas the lip tip of the second seal lip is rounded. The sealing device is characterized by being formed in a different shape . A sealing device disposed in an annular gap between two members that reciprocally move relatively,
A first seal lip which is provided on the side of the first sealed region where the liquid is sealed and which slides on the surface of one of the two members;
A second seal lip that is provided on the side of the second sealed region where the gas is sealed and slides relative to the surface of the one member,
In a sealing device for preventing gas leakage to the first sealed region and preventing liquid leakage to the second sealed region,
The shape of the lip tip of the first seal lip and the shape of the lip tip of the second seal lip are
When the first seal lip slides with respect to the surface of the one member, the thickness of the film formed by the liquid formed on the sliding portion is determined when the second seal lip slides with respect to the surface of the one member. The lip tip of the first seal lip and the lip tip of the second seal lip are both rounded and have a curvature so as to be thinner than the thickness of the film formed by the liquid formed on the sliding portion. A sealing device characterized in that the radius is configured to be smaller at the tip of the first seal lip . A plurality of annular protrusions are provided on both the inclined surface on the second sealing region side of the first seal lip and the inclined surface on the first sealing region side of the second seal lip,
These annular projections are formed by inclined surfaces on both the first sealing region side and the second sealing region side, and the one member is in a state in which these annular projections slide with respect to the surface of the one member. The sealing device according to claim 1 or 2, wherein an inclination angle of the inclined surface on the first sealing region side with respect to the surface is larger than an inclination angle of the inclined surface on the second sealing region side. . A cylinder having a shaft hole;
In a hydraulic cylinder comprising a piston inserted into the shaft hole,
In the cylinder, a first sealed area sealed with oil and a second sealed area sealed with nitrogen gas are formed,
A first seal lip is provided on the first sealing region side and a second seal lip is provided on the second sealing region side with respect to the annular gap between the inner peripheral surface of the shaft hole and the outer peripheral surface of the piston. A hydraulic cylinder characterized in that the sealing device according to claim 1, 2 or 3 is arranged.

Images