JP5169352B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device used for hydraulic / pneumatic / hydraulic equipment such as a hydraulic cylinder of a power steering, and more particularly to a combination type sealing device in which a rubber-like elastic ring and a resin seal ring are combined. Is.

  As a sealing device used for a hydraulic cylinder of a conventional power steering, for example, the one shown in FIG.

  That is, the sealing device 300 is used for the outer peripheral sliding portion of the cylinder rod 400 that is assembled so as to be reciprocally movable with respect to the housing 410, and seals the annular gap between the housing 410 and the cylinder rod 400. It is like that. The structure of the sealing device 300 includes a rubber-like elastic ring 310 attached to the bottom of an annular groove 401 provided on the outer periphery of the cylinder rod 400, and a housing 410 attached to the outer peripheral side of the rubber-like elastic ring 310. The resin seal ring 320 is slidably sealed against the resin seal ring 320.

  In the case of power steering, depending on the steering direction of the steering, the cylinder rod 400 is reciprocated by alternately applying pressure to the left and right sealed spaces separating the sealing device 300 and sealing the pressure with the sealing device 300. It assists the steering operation by itself.

  When the cylinder rod 400 reciprocates, as shown in FIG. 5 (B), the hydraulic pressure acts on the inner peripheral side of the resin seal ring 320, and the rubber-like elastic ring 310 has a groove wall on the counter pressure side. Accordingly, the force by which the rubber-like elastic ring 310 presses the resin seal ring 320 in the outer diameter direction increases, and the contact surface pressure of the resin seal ring 320 against the housing 410 increases.

  As the surface pressure increases, the sliding resistance Fr also tends to increase. The sliding resistance Fr greatly affects the steering feeling at the time of steering operation. To make the steering feeling appropriate, the sliding resistance is set. Is an important factor.

  The conventional sealing device 300 has a characteristic that the hydraulic pressure increases as the steering operation amount increases, and the sliding resistance Fr increases almost in proportion to the hydraulic pressure. In addition, when the sliding resistance Fr is reduced and the steering operation amount increases, there is a demand for increasing the sliding resistance Fr as compared with the conventional art.

  When it is desired to increase the sliding resistance, the thickness of the resin seal ring 320 is increased as shown in FIGS. 5C and 5D (from T to (T + α) in the figure), thereby forming a rubber-like shape. The sliding resistance Fr is adjusted to be high by increasing the amount of crushing of the elastic ring 310 or increasing the hardness of the rubber-like elastic ring 310.

However, these methods have a problem that the surface pressure is increased even when the pressure is low or no pressure is applied, and the sliding resistance is uniformly increased.
As a related technique, there is one disclosed in Patent Document 1.
JP 59-133867 A

  The purpose of the present invention is not only to increase the contact surface pressure when pressure is applied, but also to increase the area to which the contact surface pressure is applied without increasing the contact surface pressure when no pressure is applied. An object of the present invention is to provide a sealing device that can increase the rate of increase in dynamic resistance.

In order to solve the above problems, a sealing device of the present invention seals an annular gap between a shaft and a housing that reciprocally move relative to each other, and the groove bottom surface side of an annular groove provided on the outer periphery of the shaft A rubber-like elastic ring attached to the outer periphery of the rubber-like elastic ring, and a resin seal ring provided on the outer peripheral side of the rubber-like elastic ring and slidable with respect to the housing. In the sealing device configured to compress the resin seal ring and the groove bottom surface in the radial direction and apply the contact surface pressure by pressing the resin seal ring against the housing by its elastic restoring force,
The resin seal ring has a central region where the rubber-like elastic ring is located when no pressure is applied, and end regions extending from the central region to both sides in the axial direction, and is added to the inner peripheral surface of the end region. A taper surface that compresses and deforms the arc-shaped end portion of the rubber-like elastic body ring that moves in the anti-pressurizing direction at the time of pressure in the radial direction is provided over the entire length of the end region ,
When no pressure is applied, the rubber-like elastic ring located in the central region of the resin seal ring is used to limit the range in which contact pressure is applied to the central region
At the time of pressurization, the arc-shaped end of the rubber-like elastic ring is compressed and deformed by the tapered surface of the end region, thereby increasing the contact surface pressure and extending the range in which the contact surface pressure is applied from the center region. It is characterized in that the sliding resistance is increased by enlarging the partial area.

  According to the present invention, when no pressure is applied, the rubber-like elastic ring is located in the central region of the resin seal ring, so that the range where the contact surface pressure is applied is limited to the central region.

  When the pressure of the sealing fluid acts, the rubber-like elastic ring moves to the end region side of the resin seal ring, and the end of the rubber-like elastic ring is located between the tapered surface of the end region and the groove bottom surface of the mounting groove. The contact surface pressure increases and the sliding resistance increases, and at the same time, the range in which the contact surface pressure is applied is expanded from the central region to the end region, and the sliding resistance is further increased.

  If the cross-sectional shape of the rubber-like elastic ring is an elliptical shape whose major axis is the axial direction, it can be moved to the non-pressurizing side without twisting when moving during pressurization, resulting in twisting. Wear and breakage can be suppressed.

  As described above, according to the present invention, it is possible to increase the ratio of the increase in sliding resistance to the increase in the pressure of the sealing fluid without increasing the contact surface pressure when no pressure is applied.

  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. .

<Application example of sealing device>
First, an application example of the sealing device according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of a hydraulic cylinder to which a sealing device according to an embodiment of the present invention is applied.

The illustrated hydraulic cylinder 200 is used for power steering. As shown in this figure, the hydraulic cylinder 200 includes a cylinder 80 as a housing having a shaft hole, and a rod 70 provided in the cylinder 80 so as to be capable of reciprocating relative to the cylinder 80. Further, a driving mechanism 210 for driving the rod 70 by a steering operation is provided on one end side of the hydraulic cylinder 200.

  A sealing device 100 that seals the annular gap between the rod 70 and the cylinder 80 is provided near the center of the hydraulic cylinder 200. With this sealing device 100, sealed spaces 90 </ b> A and 90 </ b> B are formed on one side and the other side in the axial direction across the sealing device 100. Thereby, when the rod 70 moves in the axial direction by the operation of the steering, the hydraulic pressure is applied to the A part or the B part in the drawing to assist the movement of the rod 70. For example, when the rod 70 moves to the right side in the figure, the rod 70 is moved by the driving force by the driving mechanism unit 210 and the pressing force by the hydraulic pressure by applying hydraulic pressure from the A part.

  Here, when the rod 70 moves, a sliding resistance is generated between the sealing device 100 and the cylinder 80. This sliding resistance greatly affects the steering feeling of the person who steers the steering.

<Configuration of sealing device>
Next, with reference to FIG. 1, the structure of the sealing device 100 which concerns on the Example of this invention is demonstrated.

  The sealing device 100 according to the present embodiment seals an annular gap between the rod 70 and a cylinder 80 as a housing, and is mounted on the groove bottom surface 71 c side of an annular groove 71 provided on the outer periphery of the rod 70. A rubber-like elastic ring 10 and a resin seal ring 20 provided on the outer peripheral side of the rubber-like elastic ring 10 and slidable with respect to the cylinder 80. The resin seal ring 20 and the groove bottom surface 71c are compressed in the radial direction, and the contact pressure is applied by pressing the resin seal ring 20 against the cylinder 80 by its elastic restoring force. The annular groove 71 is rectangular, the groove bottom surface 71a is parallel to the axial direction, and the groove side surfaces 71a and 71b are orthogonal surfaces orthogonal to the axial direction.

  As shown in FIG. 1, the resin seal ring 20 includes a central region 21 where the rubber-like elastic ring 10 is located when no pressure is applied, and left and right end regions 22A and 22B extending from the central region 21 to both sides in the axial direction. In addition, tapered surfaces 23A and 23B are provided on the inner peripheral surfaces of the end regions 22A and 22B to compress and deform the end portions of the rubber-like elastic ring 10 that moves in the anti-pressurizing direction when pressurized. Preferable examples of specific materials for the resin seal ring 20 include PTFE and PA with filler.

The outer peripheral surfaces of the central region 21 and the end regions 22 </ b> A and 22 </ b> B are one continuous cylindrical surface and are set to be substantially the same as the inner diameter of the cylinder 80.
The inner peripheral surface 21a of the central region 21 is a cylindrical surface extending linearly in the axial direction, and one ends of tapered surfaces 23A and 23B of the end regions 22A and 22B are connected to both ends thereof. The tapered surfaces 23A and 23B are inclined surfaces that linearly incline toward the first and second sealed spaces 90A and 90B, gradually decreasing in diameter, and have the same inclination angle and length with respect to the axial direction. Therefore, it has a symmetrical shape.

  The rubber-like elastic ring 10 is an elliptical squeeze packing whose cross-sectional shape is longer in the axial direction than in the radial direction. In this example, the inner peripheral surface 11 and the outer peripheral surface 12 are not in the shape of an accurate ellipse, but are in a linear track shape, and the linear inner peripheral surface 11 and the outer peripheral surface 12 are continuous by the left and right arc-shaped portions 13A and 13B. It is a connected shape.

The inner peripheral surface 11 and the outer peripheral surface 12 have the same length, and in a free state, are slightly shorter than the inner peripheral surface 21a of the central region 21 of the resin seal ring 20, and the axial lengths of the left and right arcuate portions 13A and 13B Is longer than the length of the inner peripheral surface 21a of the central region 21, and protrudes toward the left and right end regions 22A and 22B.

  The outer diameter of the rubber-like elastic ring 10 is substantially the same as the inner diameter of the central region 21 of the resin seal ring 20 in the free state, and the inner diameter is smaller than the diameter of the groove bottom surface 71 c of the annular groove 71. .

  Therefore, when the rubber-like elastic ring 10 and the resin seal ring 20 are attached to the annular groove 71, the rubber-like elastic ring 10 is expanded outside by the groove bottom surface 71c as shown in FIG. Compressed radially between the inner peripheral surface 21a of the central region 21 of the seal ring 20 and pressed in the direction of expanding the inner peripheral surface 21a of the central region 21 of the resin seal ring 20 by its elastic restoring force. It is like that. In the compressed state, only the inner and outer cylindrical surfaces of the rubber-like elastic ring 10 are compressed, and the arcuate portions 13A and 13B are not compressed.

  When no pressure is applied, the state at the time of mounting is maintained, and the range Wo where the contact surface pressure is applied is limited to the central region 21 by the rubber-like elastic body ring 10 located in the central region 21 of the resin seal ring 20. . That is, the range in which the elastic restoring force of the rubber-like elastic ring 10 acts, mainly the outer peripheral surface of the central region 21, is pressed against the inner peripheral surface of the cylinder 80, and as shown in FIG. The contact surface pressure distribution Fo of the outer peripheral sliding portion is concentrated in the vicinity of the central region 21.

  At the time of pressurization, as shown in FIG. 1C, one arcuate portion 13B, which is the end of the rubber-like elastic ring 10, is compressed and deformed by the tapered surface 23B of the end region 22B. While increasing the surface pressure, the range W1 to which the contact surface pressure is applied is expanded from the central region to the end region to increase the sliding resistance. That is, the rubber-like elastic ring 10 is moved in the anti-pressurizing direction, in the illustrated example, to the second sealed space 90B side by the hydraulic pressure, and one arcuate portion 13B of the rubber-like elastic ring 10 is connected to the tapered surface 23B. The elastic restoring force bites into the space between the groove bottom surface 71c and the elastic restoring force acts in a direction orthogonal to the tapered surface 23B of the end region 22B of the resin seal ring 20, and the end surface of the end region 22B is The outer peripheral surface is pressed against the inner peripheral surface of the cylinder 80 while being in close contact with the groove side surface 71b.

  At this time, not all of the rubber-like elastic ring 10 moves toward the tapered surface 23B side of the end region 22B, but only a part of the rubber-like elastic ring 10 presses the inner peripheral surface 21a of the central region 21. The contact pressure distribution Fb on the outer periphery of the resin seal ring 20 is a surface pressure distribution having a pressure gradient that gradually increases from the outer peripheral surface of the central region 21 to the outer peripheral surface of the end region 22B.

  Thus, according to the present invention, when no pressure is applied, the central region 21 of the resin seal ring 20 contacts the inner periphery of the cylinder 80 with a predetermined contact surface pressure distribution Fo as shown in FIG. doing. The width Wo and the contact surface pressure distribution Fo to which the contact surface pressure is applied are the contact width W3 and the contact surface pressure distribution F3 of the resin seal ring 320 of the conventional sealing device 300 as shown in FIG. They are equivalent and have the same sliding resistance.

  At the time of pressurization, as shown in FIG. 3B, the contact surface pressure increases and the range W1 to which the contact surface pressure is applied is expanded from the central region 21 to the end region 22B. Compared with the conventional example of C), the sliding resistance is increased by the enlarged amount.

  Further, since the rubber-like elastic ring 10 has an elliptical shape with the long axis in the axial direction, it can be moved to the non-pressurizing side without twisting when moving during pressurization, As a result, twist wear and breakage can be suppressed.

  When the pressure state is shifted to the non-pressure state, the rubber-like elastic ring 10 compressed between the tapered surface 23 and the groove bottom surface 71c is restored to its shape by the elastic restoring force, and moves toward the central region 21 along the tapered surface 23. Move automatically.

  FIG. 4 is a graph of experimental results comparing the prior art and the product of the present invention regarding the relationship between the hydraulic pressure P and the sliding resistance Fr. m1 is the result of the conventional specification, the line m2 is the result of the crushing and rubber hardness increase specification, and the line n is the result of the product of the present invention.

  The conventional specification has the shape shown in FIG. 3C, the resin seal ring 320 has an axial width dimension of 1.7 cm, and the crushing / rubber hardness increase specification has the same width dimension and is made of resin. The thickness of the seal ring 320 is increased to increase the crushing margin, and the rubber hardness is increased. In the embodiment of the present invention, the width of the central region 21 is set to 1.7 cm, which is the same as the conventional specification, and the width of the end regions 22A and 22B is set to 0.8 cm.

As a result, the crushing / rubber hardness increased specification has a sliding resistance Fr that has increased from no pressure (pressure is 0 [kg · cm ² ]), while the product of the present application has no pressure, Similar to the conventional specification, the sliding resistance is almost 0 [kgf], which increases as the pressure increases, and has characteristics of approaching the crushing / rubber hardness increase specification.

  As can be seen from this graph, when trying to increase the sliding resistance by conventional methods such as crushing and increasing the hardness of the rubber, the sliding resistance increases even when the hydraulic pressure is low or when no pressure is applied. Then, when the hydraulic pressure is low or no pressure is applied, the sliding resistance is small, and when the hydraulic pressure is high, the sliding resistance is increased.

1A and 1B show a sealing device according to an embodiment of the present invention. FIG. 1A is an enlarged cross-sectional view showing a mounting groove with a two-dot chain line, and FIG. The principal part expanded sectional view of a pressure state and the figure (C) are principal part enlarged sectional views of the pressurization state which shows a mounting state. FIG. 2 is a schematic sectional view of a power steering mechanism to which the sealing device of the present invention is applied. 3 (A) and 3 (B) show the surface pressure distribution of the sliding surface of the sealing device of FIG. 1, and FIG. 3 (A) shows the surface pressure distribution in the no-pressure state, FIG. 3 (B). Is a diagram showing a surface pressure state in a pressurized state, and FIG. 5C is a diagram showing a surface pressure distribution on a sliding surface of a conventional sealing device. FIG. 4 is a graph schematically showing the relationship between the hydraulic pressure P and the sliding resistance Fr. FIG. 5 shows a sealing device according to a conventional example. FIG. 5A is an enlarged cross-sectional view of a main part in a mounted state, and FIG. 5B is an enlarged cross-sectional view of a main part in a state where pressure is applied. C) and (D) are cut end views for explaining the difference in thickness of the resin seal ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Sealing device 10 Rubber-like elastic body ring 11 Inner peripheral surface 12 Outer peripheral surface 13A, 13B Arc-shaped part 20 Resin seal ring 21 Central area 21a Inner peripheral surface 22A, 22B End area 23A, 23B Tapered surface 70 Rod 71 Annular groove 71c Groove bottom surface 80 Cylinder 90A, 90B Sealing space 300 Sealing device 310 Rubber elastic ring 320 Resin seal ring 400 Cylinder rod 401 Annular groove 410 Housing

Claims (2)

This seals an annular gap between the shaft and the housing that reciprocally move relative to each other. The rubber-like elastic ring that is attached to the groove bottom surface of the annular groove provided on the outer periphery of the shaft, and the rubber-like elasticity A resin seal ring provided on the outer peripheral side of the body ring and slidably with respect to the housing, and compressing the rubber-like elastic ring in a radial direction between the resin seal ring and the groove bottom surface, In the sealing device configured to apply a contact surface pressure by pressing the resin seal ring against the housing by the elastic restoring force,
The resin seal ring has a central region where the rubber-like elastic ring is located when no pressure is applied, and end regions extending from the central region to both sides in the axial direction, and is added to the inner peripheral surface of the end region. A taper surface that compresses and deforms the arc-shaped end portion of the rubber-like elastic body ring that moves in the anti-pressurizing direction at the time of pressure in the radial direction is provided over the entire length of the end region ,
When no pressure is applied, the rubber-like elastic ring located in the central region of the resin seal ring is used to limit the range in which contact pressure is applied to the central region
At the time of pressurization, the arc-shaped end of the rubber-like elastic ring is compressed and deformed by the tapered surface of the end region, thereby increasing the contact surface pressure and extending the range in which the contact surface pressure is applied from the center region. A sealing device characterized in that it is configured to increase sliding resistance by expanding to a partial area.
The sealing device according to claim 1, wherein a cross-sectional shape of the rubber-like elastic ring is an elliptical shape having a major axis in the axial direction.

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