JP5177391B2 - Piston seal structure - Google Patents

Description

  The present invention relates to a piston seal structure used for a pneumatic cylinder or the like.

One example of a mechanical actuator is a pneumatic cylinder. When the pneumatic cylinder performs mechanical work, rubber seals, piston rings, piston seals, etc. are used to reduce air leakage. The rubber seal has a problem that the heat-resistant temperature cannot be raised, and the piston ring has a problem that it leaks from the cut. In general, in a piston seal, when attempting to reduce leakage, the frictional force of the seal portion increases, which causes a conflicting problem that prevents smooth sliding of the piston. For this reason, it is difficult to reduce both at the same time. FIG. 7A is a conceptual diagram in the case where the seal pressing load is large and the sealing performance is good, but the sliding resistance of the piston 32 with respect to the cylinder 30 increases, and FIG. 7B is the seal pressing load. Although it is small and sliding resistance becomes small, it is a conceptual diagram in case leakage becomes large.
In addition, there is a method of digging a groove that can store the seal on the cylinder side and storing the lip seal or the originally curved seal in the groove, but since the material of the lip seal cannot be made of metal, a large pressure is required during assembly. Is necessary, and there is a problem that the lip is cut. Further, the originally curved seal has a problem that the surface pressure is low.

  Further, conventionally, a method is known in which a groove capable of accommodating a seal is formed on the cylinder side, and the seal and the sheet (resin material) are simultaneously pressed from the outer periphery using the groove. For example, Patent Document 1 proposes a seal structure in which a seal ring in contact with a cylinder and an O-ring that presses the seal ring are accommodated in a seal groove provided on the outer periphery of a piston.

Further, conventionally, a technique for reducing the above problem has been proposed. Similarly, Patent Document 2 proposes a seal structure in which a seal ring and an O-ring are accommodated in a seal groove provided on the outer periphery of the piston, and the seal ring is curved so that the contact with the cylinder is close to a line contact. Has been.
Japanese Utility Model Publication No. 5-73277 JP-A-9-152033

  Incidentally, as shown in FIG. 8A, in the seal structure in which the seal ring 35 and the O-ring 36 are accommodated in the seal groove 31, a pressing load is generated by the contraction force of the O-ring 36, and the pressing force of the seal ring 35 increases. , Air leakage can be suppressed. That is, as shown in FIG. 8B, even if air enters the seal groove 31 from one end of the seal ring 35, the O-ring 36 is contracted to securely seal the other end side to prevent air leakage. . At this time, if there is a gap between the O-ring 36 and the side wall of the seal groove, no load is received from the cylinder 30 and only a pressing force against the seal ring 35 is generated. However, as described above, when there is a gap between the O-ring 36 and the side wall of the seal groove and the O-ring 36 can move to the left and right, there is air intrusion at one end of the seal ring 36 and the other end. When the pressing force is increased by the expansion / contraction force of the O-ring 36, the O-ring 36 moves to prevent air leakage, so that a time delay occurs in the seal, and this time delay causes air leakage and energy loss. There is a problem that will occur.

  On the other hand, as shown in Patent Document 2, when the O-ring 36 and the seal ring 35 are pressed on the inner peripheral surface of the seal groove 31, as shown in FIG. The contact area between the seal ring 35 and the cylinder 30 is increased. As a result, there is a problem in that the sliding resistance of the piston 32 increases and the seal ring 35 is extremely worn.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide a piston seal structure capable of effectively preventing leakage without applying an excessive pressing load to the seal ring.

That is, of the piston seal structure of the present invention, the first present invention includes a cylinder,
A piston inserted into the cylinder and reciprocating in the cylinder axial direction;
A seal ring having rising portions at both ends of a ring-shaped flat plate bottom ;
A piston seal structure for a pneumatic cylinder with
A seal groove is provided along one of the cylinder and the piston along the circumferential direction;
The seal ring has a width larger than the width of the seal groove, and the rising portions increase their opening widths toward the tip so that the width between the rising portion end portions is larger than the width of the seal groove. The seal ring is bent and bent at both ends in the width direction so that the bottom of the seal ring is bent and loaded into the seal groove, and the bottom of the seal ring contacts the cylinder or the piston in a part of the width direction. In addition, both the outer surfaces of the rising portion are bent into close contact with the end surface in the width direction of the seal groove by a reaction force to seal the cylinder and the piston.

  That is, according to the present invention, the reaction force due to the bending is always applied to the seal ring, and both end portions in the width direction of the seal ring are in close contact with the seal groove. Further, the surface of the bent seal ring can be pressed against the sliding surface side with an appropriate pressing load. As a result, even when air or the like enters one end side of the seal ring, the other end of the seal ring is pressed against the seal groove with a stronger force, and a valve action that reliably prevents air leakage is obtained. At this time, the contact pressure between the seal ring and the cylinder or the piston does not increase, and the seal ring having a bent shape is only in contact with the mating piston or cylinder with a small contact area, and the sliding resistance is reduced. Reduce significantly. In addition, air leakage and the like are prevented on the contact surface without increasing the sliding resistance by an appropriate pressing load.

  The piston seal structure according to a second aspect of the present invention is the piston seal structure according to the first aspect, wherein the width b between the rising portion end portions is larger than the width a of the bottom portion of the seal ring, and a <the groove width <b Thus, the bottom portion of the seal ring is curved when loaded, and the seal ring and the cylinder or piston are in close contact with each other over the circumference.

  The piston seal structure of the third aspect of the present invention is the first or second aspect of the present invention, wherein the seal groove is provided in a cylinder, and a ring-shaped seal made of an elastic body is disposed on the outer periphery of the seal ring, The seal groove is loaded together with the seal ring.

  The ring-shaped seal made of an elastic material such as an O-ring or spring can increase the pressing load of the seat ring, and it can prevent air leakage from the gap with the inner circumference, which can occur when the seal ring inner diameter increases due to deterioration over time or heat. Can be reduced.

  The piston seal structure according to a fourth aspect of the present invention is characterized in that, in the third aspect of the present invention, the ring-shaped seal is disposed so as to contact both end faces in the width direction of the seal groove.

  According to the fourth aspect of the present invention, since the ring-shaped seal is in contact with the seal groove, the ring-shaped seal does not move when air or the like flows into the seal groove, and a stable leakage prevention effect is obtained. It is done.

  In the piston seal structure of the fifth aspect of the present invention, in the third or fourth aspect of the present invention, the seal groove is divided into two grooves having different groove widths in the inner and outer peripheral directions, and is in contact with the ring-shaped seal. A stepped groove structure having a groove width and a groove width in contact with the seal ring is provided.

  In the piston seal structure of the sixth aspect of the present invention, in any one of the third to fifth aspects of the present invention, the ring-shaped seal is loaded in the seal groove without contacting the groove bottom of the seal groove. It is characterized by.

That is, according to the piston seal structure of the present invention, a cylinder, a piston inserted in the cylinder and reciprocating in the cylinder axial direction, and a seal ring having rising portions at both ends of a ring-shaped flat bottom A piston seal structure for a pneumatic cylinder comprising: a seal groove along a circumferential direction in one of the cylinder and the piston, and the seal ring having a width larger than the width of the seal groove And the rising portions rise so that the opening width of each of the rising portions increases toward the tip, and has a width between the rising portion end portions larger than the width of the seal groove, and the seal ring has both end portions in the width direction. deflected bottom of the seal ring is loaded into the seal groove by bending the seal ring bottom is part of a width direction in contact with the cylinder or piston Since both the outer surface of Rutotomoni the rising portion, characterized in that sealing the piston and the cylinder in close contact by the reaction force deflection in the width direction end face of the seal groove, resulting in a seal ring loaded by providing a deflection Air leakage can be effectively prevented by the bending reaction force. Further, the seal ring having a bent shape contacts with a sliding piston or cylinder with a small contact area, and the sliding resistance is greatly reduced.

(Embodiment 1)
Below, the piston seal structure of one Embodiment of this invention is demonstrated based on FIG.
In this embodiment, description will be made assuming that the inner peripheral wall of the cylinder 1 has the seal groove 2.
A seal groove 2 having a desired groove width and groove depth is formed on the inner peripheral wall of the cylinder 1 over the entire circumference. The seal ring 10 loaded in the seal groove 2 has an inner peripheral diameter substantially the same as the cylinder diameter, and as shown in FIG. 1 (a), a ring-shaped flat sheet portion corresponding to the bottom of the seal ring. 10a and ring-shaped rising portions 10b and 10b protruding to the outer peripheral sides of both ends, and is made of a flexible material. Further, in the seal ring 10, as shown in FIG. 1 (a), the rising portions 10b and 10b rise so that the opening width increases, and the width b between the both end portions is the width of the sheet portion 10a. The width b is larger than the groove width, and the width a is smaller than the groove width. In the seal ring 10, the heights of the rising portions 10b and 10b are smaller than the groove depth. Note that the present invention does not exclude the case where the width a of the sheet portion 10a is larger than the groove width, as long as it can be loaded into the groove by bending.

  When the seal ring 10 is loaded into the seal groove 2, as shown in FIG. 1 (b), the inner surfaces of the rising portions 10b and 10b are bent so as to approach each other, and the width thereof is set to the seal groove. Match the groove width of 2. As shown in FIG. 1C, the bent seal ring 10 is inserted into the seal groove 2 in a bent state, and a part of the central portion of the seat portion 10a extends over the outer peripheral surface of the piston 5 in the circumferential direction. And place it in a uniform contact position. With this arrangement, the seal ring 10 is in close contact with both outer surfaces of the rising portions 10 b and 10 b being pressed against the end surface in the width direction of the seal groove 2 by the bending reaction force.

  Next, a mechanism for reducing both air leakage and sliding resistance in the piston seal structure will be described with reference to FIG. Consider moving the piston 5 from left to right as shown in FIG. 2 (b) with the cylinder 1 fixed and the piston 5 arranged as shown in FIG. 2 (a). As the piston 5 moves, the air that is about to flow into the seal groove 2 pushes the rising portion 10 b at the left end of the seal ring 10 and flows into the seal groove 2. However, since the seal ring 10 is bent and loaded in the seal groove 2, the pressure at which the rising portion 10 b comes into close contact with the seal groove is strong, and the inflow of air into the seal groove 2 is suppressed.

  The air that has flowed into the seal groove 2 pushes the rising portion 10 b at the right end from the inside of the seal groove 2 toward the wall of the cylinder 1. Furthermore, since the rising portion 10b at the right end is pressed against the seal groove 2 by the bending reaction force, the rising portion 10b at the right end of the seal ring 10 serves as a valve, and the air that flows in from the left end of the seal ring 10 Stagnate inside the seal groove 2. Thereby, air leakage is reduced.

Further, the seat portion 10a of the seal ring 10 is in contact with the outer peripheral surface of the piston 5 with a small contact area and has a small sliding resistance. However, the seat portion 10a is pressed moderately and strongly against the piston 5 side by the bending reaction force (the pressing load increases), and even if the contact area is small, air leaks between the seat portion 10a and the outer peripheral surface of the piston 5 Is effectively prevented.
Based on the above, the piston seal structure of the present invention has an effect of effectively preventing air leakage as well as having a small sliding resistance.

(Embodiment 2)
In the first embodiment, only the loading of the seal ring 10 has been described. At the time of loading, as shown in FIG. 3, a ring-shaped seal 11 made of an elastic body is arranged on the outer peripheral side of the seal ring 10 to seal the seal ring. The ring-shaped seal 11 can be loaded into the seal groove 2 together with 10.
In this embodiment, the ring-shaped seal 11 is composed of an O-ring, the diameter of which is slightly smaller than the groove width of the seal groove 2, and is positioned between the rising portions 10b and 10b so as to be in close contact with the seal groove 2. It is located close to the inner surface side of the rising parts 10b, 10b. As a result, the ring-shaped seal 11 and the both end surfaces of the seal groove 2 have a small gap. Further, the ring-shaped seal 11 does not reach the bottom of the seal groove (the cylinder inner peripheral side bottom), and has a gap with the bottom of the seal groove 2. Thereby, an excessive pressing load is not applied to the seal ring 10 via the ring-shaped seal 11.

  Next, a mechanism for reducing both air leakage and sliding resistance in the piston seal structure will be described. Consider that the cylinder 1 is fixed and the piston 5 is moved from left to right as shown in FIG. As the piston 5 moves, the air that is about to flow into the seal groove 2 from the left side pushes the rising portion 10 b at the left end of the seal ring 10 and flows into the seal groove 2. However, since the seal ring 10 is bent and loaded in the seal groove 2, the pressure at which the rising portion 10 b comes into close contact with the seal groove is strong, and the inflow of air into the seal groove 2 is suppressed. Further, the seat portion 10a of the seal ring 10 is in contact with the outer peripheral surface of the piston 5 with a small contact area and has a small sliding resistance, but the seat portion 10a is pressed against the piston side reasonably strongly by a bending reaction force. (The pressing load increases), and air leakage between the seat portion 10a and the outer peripheral surface of the piston 5 is effectively prevented.

The air that has flowed into the seal groove 2 pushes the rising portion 10 b at the right end from the inside of the seal groove 2 toward the wall of the cylinder 1. Furthermore, since the rising portion 10b at the right end is pressed against the seal groove 2 by the bending reaction force, the rising portion 10b at the right end of the seal ring 10 serves as a valve, and the air that flows in from the left end of the seal ring 10 Stagnate inside the seal groove 2. Thereby, air leakage is reduced. In this operation, the ring-shaped seal 11 moves to increase the pressing load on the rising portion 10b at the right end. However, even if the movement of the ring-shaped seal 11 is delayed, the bending reaction force causes the seal ring 10 to move. Since the right end sufficiently serves as a valve, there is no air leak. The valve action is further strengthened by the ring-shaped seal 11 that moves with a delay. The ring-shaped seal 11 reliably applies a pressing load to the sheet portion 10a, and prevents air leakage due to deterioration with time of the sheet portion 10a.
Based on the above, the piston seal structure of the present invention has an effect of effectively preventing air leakage as well as having a small sliding resistance.

(Embodiment 3)
Next, in the second embodiment, the description has been made assuming that there is a gap between the ring-shaped seal 11 and both side walls of the seal groove 2, but the gap between the ring-shaped seal and both side walls of the seal groove 2 has been described. The ring-shaped seal may be loaded in a state where both sides of the ring-shaped seal are in contact with both end surfaces in the width direction of the seal groove 2. Also in this embodiment, as shown in FIG. 4, the seal ring 10 is bent and loaded into the seal groove 2, and a ring-shaped seal 12 having substantially the same diameter as the seal groove 2 is disposed on the outer peripheral side of the seal ring 10. Place and load into seal groove 2.

  The mechanism for reducing both air leakage and sliding resistance when moving the piston 5 is substantially the same as in the second embodiment, but the ring-shaped seal 12 is in contact with the end surface in the width direction of the seal groove 2. Thus, even when air flows into the seal groove 2, the ring-shaped seal 12 does not move even if it is elastically deformed, so that a stable pressing load can be applied to the seat portion 10a. Also in this embodiment, there is a gap between the ring-shaped seal 12 and the bottom of the seal groove, and an excessive pressing load is not applied to the seal ring 10 via the ring-shaped seal 12.

(Embodiment 4)
Next, still another embodiment will be described with reference to FIG.
The seal groove 2 of this embodiment has a stepped groove structure including a narrow groove portion 2a provided on the inner peripheral side of the cylinder 1 and a wide groove portion 2b provided on the outer peripheral side of the groove portion 2a. . The seal ring 10 has a larger width than the groove 2b, and is bent and loaded in the groove 2b as in the above embodiments. A ring-shaped seal 13 is disposed on the outer peripheral side of the seal ring 10 so as to be positioned between the rising portions 10b and 10b and the outer peripheral surface of the seat portion 10a. The ring-shaped seal 13 has a size that extends from the groove 2b to the groove 2a and that both sides thereof are in contact with both end faces of the groove 2a. However, there is a gap with the bottom of the groove 2a.

  Also in the fourth embodiment, in the groove portion 2b, the outer surfaces of the rising portions 10b and 10b at both ends in the width direction of the seal ring 10 are pressed against the end surfaces in the width direction of the groove portion 2b by the reaction force of the seal ring 10 in the width direction. As shown in FIG. 5B, even when air flows into the seal groove 2 from one of the rising portions 10b and 10b, air leakage is effective due to the valve action of the other rising portion 10b. To be prevented. Further, since both sides of the outer periphery of the ring-shaped seal 13 are in contact with both end surfaces of the groove 2a, even when air flows into the seal groove 2, it is pushed by the rising portion 10b on the air inflow side and elastically deforms. No movement occurs, and a pressing load can be stably applied to the seat portion 10a of the seal ring 10.

  In addition, since the sealing performance is improved if the side surface in the width direction of the seal ring is in contact with both ends of the seal groove on a wide surface, when the seal ring is bent and loaded into the seal groove, both rising parts are sealed. It is desirable to match the inclination angle of the rising portion with the inclination angle of both end faces of the seal groove so as to be along the groove. A modification of the stepped groove structure is shown in FIG.

  6A, as in the embodiment shown in FIG. 5, the outer surface inclination angle of the rising portions 100b, 100b of the seal ring 100 and the inclination angle of both end surfaces of the wide outer peripheral groove portion 20b of the seal groove 20 are substantially perpendicular to each other. It is to match. Both end faces of the narrow inner circumferential groove 20a of the seal groove 20 are also perpendicular. When the seal ring 100 is bent and loaded in the groove portion 20b, both outer surfaces of the rising portions 100b and 100b can make surface contact with both end surfaces in the width direction of the groove portion 20b in a wide area.

  FIG. 6B shows a shape in which both outer surfaces of the rising portions 101b and 101b of the seal ring 101 expand outward toward the tip, and the seal groove 21 in which the seal ring 101 is loaded has a wide outer periphery. Both end surfaces in the width direction of the side groove portion 21b are inclined so as to become narrower toward the outer peripheral side, and the inner peripheral side groove portion 21a having a narrow width in the seal groove 21 has both end surfaces at right angles. Also in this modified example, when the seal ring 101 is bent and loaded, both outer surfaces of the rising portions 101b and 101b are in surface contact with both end surfaces in the width direction of the groove portion 21b in a wide area.

FIG. 6C shows a shape in which both outer surfaces of the rising portions 102b and 102b of the seal ring 102 are inclined inward toward the tip, and the seal groove 22 into which the seal ring 102 is loaded has a wide width. Both end surfaces in the width direction of the outer peripheral groove portion 22b are inclined so as to become wider toward the outer peripheral side, and the inner peripheral groove portion 22a having a narrow width in the seal groove 22 has both end surfaces at right angles. Also in this modified example, when the seal ring 102 is bent and loaded, both end surfaces of the rising portions 102b and 102b are in surface contact with both end surfaces in the width direction of the groove portion 22b in a wide area.
The shape of the seal ring and the shape of the seal groove are exemplified, and the present invention is not limited to these shapes.

Although the above embodiment has been described as having a seal groove on the cylinder side, a seal groove and a ring-shaped seal may be loaded by providing a seal groove on the piston side.
Further, in each of the above embodiments, the piston seal structure in the pneumatic cylinder has been described. However, the present invention is not limited to this, and a piston and a cylinder that prevent fluid leakage by reducing sliding resistance. It can be applied to various uses in combination.
As described above, the present invention is not limited to the description of the above-described embodiment, and appropriate modifications can be made without departing from the scope of the present invention.

It is a figure which shows loading of the seal ring in the piston seal structure in one Embodiment of this invention. Similarly, it is a figure which shows embodiment with which the seal ring and the ring-shaped seal were loaded. It is a figure which shows the piston seal structure and operation | movement in other embodiment of this invention. It is a figure which shows the piston seal structure in other embodiment of this invention. It is a figure which shows the piston seal structure and operation | movement in further another embodiment of this invention. Similarly, it is a figure which shows the example of a change of the shape of a seal ring and a seal groove. It is a figure explaining the relationship between the leakage in a piston seal structure, and sliding resistance. It is a figure explaining the operation | movement in the conventional piston seal structure. It is a figure which shows the other conventional piston seal structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Seal groove 2a Groove part 2b Groove part 5 Piston 10 Seal ring 10a Seat part 10b Standing part 11 Ring-shaped seal 12 Ring-shaped seal 13 Ring-shaped seal

Claims (6)

A cylinder,
A piston inserted into the cylinder and reciprocating in the cylinder axial direction;
A seal ring having rising portions at both ends of a ring-shaped flat plate bottom ;
A piston seal structure for a pneumatic cylinder with
A seal groove is provided along one of the cylinder and the piston along the circumferential direction;
The seal ring has a width larger than the width of the seal groove, and the rising portions increase their opening widths toward the tip so that the width between the rising portion end portions is larger than the width of the seal groove. The seal ring is bent and bent at both ends in the width direction so that the bottom of the seal ring is bent and loaded into the seal groove, and the bottom of the seal ring contacts the cylinder or the piston in a part of the width direction. In addition , the piston seal structure is characterized in that both outer surfaces of the rising portion are in close contact with a width direction end surface of the seal groove by a reaction force to seal the cylinder and the piston.   The width b between the rising portion end portions is larger than the width a of the bottom portion of the seal ring and a <the groove width <b, so that the bottom portion of the seal ring is curved during loading, The piston seal structure according to claim 1, wherein the cylinder or the piston is in close contact with the circumference uniformly. Said seal groove is provided in said cylinder,
3. The piston seal structure according to claim 1, wherein a ring-shaped seal made of an elastic body is disposed on an outer periphery of the seal ring, and is loaded into the seal groove together with the seal ring.   4. The piston seal structure according to claim 3, wherein the ring-shaped seal is disposed so as to contact both end surfaces in the width direction of the seal groove. The seal groove is divided into two grooves having different groove widths in the inner and outer circumferential directions,
5. The piston seal structure according to claim 3, wherein the piston seal structure has a stepped groove structure having a groove width in contact with the ring-shaped seal and a groove width in contact with the seal ring.   The piston seal structure according to any one of claims 3 to 5, wherein the ring-shaped seal is loaded in the seal groove without contacting the groove bottom of the seal groove.

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