JP2001295928A - Packing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packing 1 capable of securely sealing even in the case where the positive pressure or the negative pressure is applied from one side of the axial direction of the installed packing 1. SOLUTION: A packing 1 installed at a part, to which the positive pressure or the negative pressure is applied from one side of the axial direction, between a fitting member provided in an inner peripheral side and a counter member provided in an outer peripheral side has an annular base part 2 made of the rubbery elastic material and to be fitted on the periphery of the fitting member and a lip part 3 integrally formed with the peripheral side of the base part 2 so as to be tightly brought in contact with the counter member. The lip part 3 is formed with the inclination from a base part 3a thereof toward a tip part 3b so as to be gradually inclined from a pressure side A toward a counter-pressure side B, and the tip 3b of the lip part 3 to be tightly brought in contact with the counter member is provided with a taper surface 4 gradually enlarged from the pressure side A toward the counter-pressure side B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packing which is a kind of a sealing device, and more particularly to a packing in which a negative pressure acts on the packing in a mounted state even when a positive pressure acts from one of its axial directions. However, the present invention relates to a lip packing capable of reliably performing a sealing action. The packing of the present invention is used as a seal for a resin housing,
For example, it is used for an injector or the like.

[0002]

2. Description of the Related Art A lip packing is generally used as a seal between, for example, a shaft and a housing provided with a shaft hole through which the shaft is inserted and where the dimensional accuracy of the housing varies greatly. The lip packing used for this type of application is formed in a shape (a shape and a size that is easy to follow) in which the lip portion is easily deformed in order to improve the followability to the dimensional accuracy variation.
Therefore, the lip portion is set to have a sealing direction so that the cover is backed up by the self-sealing function.

However, in recent years, the use environment has been various, and the pressure resistance direction may be both positive pressure and negative pressure. In addition, the dimensional accuracy of the housing has been further reduced due to the weight reduction (plasticization) of the housing. I have.

In such an environment where both positive pressure and negative pressure act from one side in the axial direction, squeeze packing is generally used instead of lip packing. However, according to squeeze packing, the dimensional accuracy of the housing is reduced. It is necessary to set the crushing rate (the crushing rate at the center of gravity (standard dimension), the maximum crushing rate) at the time of mounting in order to improve the followability to the variation of In addition, inconveniences such as a decrease in mountability due to an increase in the insertion load and a breakage of the packing due to excessive compression may occur.

[0005] On the other hand, in the lip packing, although the insertion load is smaller than that of the squeeze packing, since the direction of the seal is set as described above, the seal can be formed in both positive pressure and negative pressure. Can not.

However, as described above, the squeeze packing cannot cope with the mounting problem and the like, so the lip type packing, not the squeeze type packing, is inevitably subjected to both positive and negative pressures. It is necessary to consider the shape or structure that can be sealed.

[0007]

SUMMARY OF THE INVENTION In view of the above points, the present invention can reliably perform a sealing operation regardless of whether a positive pressure or a negative pressure is applied from one axial direction of a mounted packing. The aim is to provide a possible lip packing. Another object of the present invention is to provide a lip packing that has higher pressure resistance to positive pressure and negative pressure than conventional lip packing, can follow variations in the dimensional accuracy of the housing, and can improve sealing performance. And

[0008]

According to a first aspect of the present invention, there is provided a packing according to the present invention, wherein a positive pressure is applied from one axial side between a mounting member on an inner peripheral side and a mating member on an outer peripheral side. Or a packing attached to a location where a negative pressure acts, an annular base made of a rubber-like elastic material fitted on the outer periphery of the mounting member, and integrally formed on the outer peripheral side of the base, and A lip portion that is in close contact with the member, wherein the lip portion is formed so as to be gradually inclined from the pressure side to the counter pressure side from its base end to the tip, and the lip is in close contact with the counterpart member. The tip of the lip is provided with a tapered surface whose diameter gradually increases from the pressure side to the counter pressure side.

A packing according to a second aspect of the present invention is mounted between an inner peripheral mounting member and an outer peripheral mating member at a position where a positive pressure or a negative pressure acts from one side in the axial direction. A packing, an annular base made of a rubber-like elastic material fitted to the outer periphery of the mounting member, a lip formed integrally with the outer periphery of the base and closely contacting the mating member; An annular projection that is integrally formed on the counter pressure side and protrudes on the counter pressure side from the base of the lip portion, and has an inner peripheral surface of the base and the protrusion, the counter pressure side from the pressure side. The lip portion is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end to the tip end, and the mating portion is formed. At the tip of the lip that is in close contact with the member, The straight cylindrical surface is provided on direction and is characterized in.

The packing according to the third aspect of the present invention is mounted between the inner peripheral mounting member and the outer peripheral mating member at a position where a positive pressure or a negative pressure acts from one side in the axial direction. A packing, an annular base made of a rubber-like elastic material fitted to the outer periphery of the mounting member, a lip formed integrally with the outer periphery of the base and closely contacting the mating member; An annular counter-pressure-side projection formed integrally with the counter-pressure side and protruding toward the counter-pressure side from the base of the lip; and Also has an annular pressure-side projection protruding toward the pressure side, and has a diameter gradually increasing from the pressure side to the counter-pressure side on the inner peripheral surface of the base, the counter-pressure side protrusion and the pressure-side protrusion. The lip portion is provided with a tapered surface that reduces Is formed to gradually slope from the pressure side over the tip from its proximal end to the counter-pressure side, the tip portion of the lip portion closely to the mating member,
A straight cylindrical surface is provided in the axial direction.

In the packing according to the first aspect of the present invention having the above structure, the lip portion is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end to the tip. Since the tip of the lip is provided with a tapered surface whose diameter gradually increases from the pressure side to the counter pressure side, when a positive pressure acts on the packing from the pressure side, the positive pressure As a result, the lip portion is pressed, and the tip portion of the lip portion having the tapered surface enters at an angle such that it penetrates the inner peripheral surface of the mating member. Therefore, the close contact force of the lip portion with the mating member is increased, and the sliding resistance is increased, so that a state in which the lip portion is hardly deformed is realized, and it is possible to secure a necessary sealing property. The close contact force and sliding resistance of the lip portion against the mating member increase within a certain range of pressure in accordance with the magnitude of the positive pressure acting on the packing.

Further, when a negative pressure acts on the packing from the same pressure side, the negative pressure causes the lip to be sucked and the tip of the lip to be strongly pressed against the inner peripheral surface of the mating member. Also, it is possible to secure necessary sealing properties.

When the rigidity of the lip portion is reduced in order to ensure the sealing performance when the dimensional accuracy of the mating member such as the housing is low as described above, the lip portion is deformed by the pressure acting on the lip portion, and the original seal There is a possibility that the performance is reduced. In view of this, the present invention increases the sliding resistance of the lip portion by the above-described configuration to reduce a change in the position of the lip tip, thereby securing a necessary sealing property.

Further, the present invention has the above configuration.
In the packing according to the above, a projection is provided on the counter pressure side of the base, and a taper surface whose diameter is gradually reduced from the pressure side to the counter pressure side is provided on the inner peripheral surface of the base and the projection, and the lip is formed. Because it is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end to the tip end, and since the tip of the lip has a straight cylindrical surface in the axial direction, When the packing is fitted on the outer periphery of the mounting member, the base and the projection are deformed such that the tapered portion provided on the inner peripheral surface of the base and the projection is deformed into a cylindrical shape along the outer peripheral surface of the mounting member. The inclination angle of the lip changes accordingly, and the axially straight cylindrical surface provided at the tip of the lip gradually increases in diameter from the pressure side to the counter pressure side. Deformed like this. Lip portion is in close contact with the mating member in posture. Therefore, when a positive pressure acts on the packing in such a deformed posture from the pressure side, the lip is pressed by the positive pressure, and the tip of the lip deformed into a tapered surface shape becomes the inner periphery of the mating member. Enter at an angle that pierces the surface. Therefore, the close contact force of the lip portion with the mating member is increased, and the sliding resistance is increased, so that a state in which the lip portion is hardly deformed is realized, and it is possible to secure a necessary sealing property. The close contact force and sliding resistance of the lip portion against the mating member increase within a certain range of pressure in accordance with the magnitude of the positive pressure acting on the packing.

When a negative pressure acts on the packing from the same pressure side, the negative pressure causes the lip to be sucked and the tip of the lip to be strongly pressed against the inner peripheral surface of the mating member. Again, it is possible to ensure the necessary sealing properties.

Further, since the tapered surface is provided on the inner peripheral surface of the base and the projection, the packing can increase the surface pressure against the mounting member, and the projection can be formed at the base of the lip. Because it is formed so as to protrude more to the opposite pressure side, when a positive pressure acts on the packing, the projection serves as a support, suppresses rotation of the lip, and prevents the lip from rotating with respect to the mating member. It is possible to increase the surface pressure.

Further, the present invention has the above configuration.
In the packing by the above, a counter pressure side protrusion is provided on the counter pressure side of the base, a pressure side protrusion is provided on the pressure side of the base, and an inner peripheral surface of the base, the counter pressure side protrusion and the pressure side protrusion is provided. A tapered surface is provided in which the diameter gradually decreases from the pressure side to the counter pressure side, and the lip is formed so that the lip is gradually inclined from the pressure side to the counter pressure side from the base end to the tip end. At the same time, since the tip of the lip is provided with a straight cylindrical surface in the axial direction, when the packing is fitted on the outer periphery of the mounting member, the inner portion of the base, the counter-pressure-side protrusion and the pressure-side protrusion is formed. The base, the counter-pressure-side protrusion and the pressure-side protrusion are deformed such that the tapered portion provided on the peripheral surface is deformed into a cylindrical surface along the outer peripheral surface of the mounting member,
The inclination angle of the lip changes accordingly, and the axially straight cylindrical surface provided at the tip of the lip becomes a tapered surface whose diameter gradually increases from the pressure side to the counter pressure side. It is deformed, and the lip portion comes into close contact with the mating member in the deformed posture. Therefore, when positive pressure acts on the packing in the deformed posture from the pressure side,
The lip is pressed by this positive pressure, and the tip of the lip deformed into a tapered surface enters at an angle such that it penetrates the inner peripheral surface of the mating member. Therefore, the close contact force of the lip portion with the mating member is increased, and the sliding resistance is increased, so that a state in which the lip portion is hardly deformed is realized, and it is possible to secure a necessary sealing property. The close contact force and sliding resistance of the lip against the mating member increase in accordance with the magnitude of the positive pressure acting on the packing.

When a negative pressure acts on the packing from the same pressure side, the negative pressure causes the lip to be sucked and the tip of the lip to be strongly pressed against the inner peripheral surface of the mating member. Again, it is possible to ensure the necessary sealing properties.

Further, since the inner peripheral surface of the base portion, the non-pressure side protrusion and the pressure side protrusion is provided with a tapered surface,
It is possible to increase the surface pressure of the packing against the mounting member, and since the non-pressure side protrusion is formed so as to protrude more toward the counter pressure side than the base of the lip portion, the packing is positively mounted. When pressure is applied, the projection serves as a support, thereby suppressing rotation of the lip and increasing the surface pressure of the lip against the mating member. Further, since the pressure side protrusion is formed so as to protrude more toward the pressure side than the base of the lip, even when a negative pressure is applied to the packing, the protrusion serves as a support, and the lip is formed. Can be suppressed.

In addition, the present invention has the following contents.

That is, using a lip type seal as a basic shape,

A projection (also referred to as a projection) is provided at the end on the inner diameter side, and the inner diameter surface is tapered. The surface pressure of the inner diameter portion is increased by the projections, and the projections are arranged at the ends to suppress the rotation of the lip portion at the time of positive pressure and increase the surface pressure of the lip portions.

[0023] A cylindrical surface (also referred to as a straight portion) is provided at the tip of the lip to provide resistance to the movement of the tip of the lip, thereby making the lip more difficult to move. The straight part is not parallel to the inner diameter taper, so that when the inner diameter surface is hung on the shaft, it is set to an acute angle with the outer housing surface, and when the positive pressure is applied, the lip tip straight part moves in the pressure direction , Enter the housing at an angle that pierces the inside diameter of the housing to provide more resistance.

Since the dimensional variation of the housing is large, the compression ratio width is large between the minimum crushing and the maximum crushing, and the lip must also follow this variation. Originally, the lip portion often has a shape that is difficult to deform even when subjected to pressure, but on the other hand, the lip portion must have a shape that is easily deformed at the time of maximum crushing. In a structure in which the thickness of the lip portion is gradually increased in order to increase the rigidity of the lip portion, the base portion becomes too thick, and the lip portion cannot be deformed at the time of maximum compression, and extreme stress is applied. In order to improve the pressure resistance by giving priority to the deformation follow-up property, it is possible to respond to the above conditions and items at the time of positive pressure, but since the pressure resistance at the time of negative pressure needs to be improved, the negative pressure Provide a deformation receiving part on the direction side, and gradually build up with lip and smooth round.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a half section of a packing 1 according to a first embodiment of the present invention, and the packing 1 is configured as follows. The packing 1 has a shaft (not shown, see FIG. 2) as an inner peripheral mounting member and a housing (not shown) as a mating member on the outer peripheral side.
And a lip-type packing made of a rubber-like elastic material, which is mounted at a position where a positive pressure or a negative pressure acts from one axial direction (the lower side in the figure). The outer peripheral surface of the shaft and the inner peripheral surface of the housing are each formed in a cylindrical shape straight in the axial direction.

First, the packing 1 has an annular base 2 fitted on the outer periphery of the shaft, and a lip portion 3 which is in close contact with the inner peripheral surface of the shaft hole of the housing is integrally formed on the outer periphery of the base 2. The lip portion 3 is formed so as to gradually incline from the pressure side (upper side in the figure) A to the counter pressure side (upper side in the figure) B from the base end 3a to the tip 3b. I have.

A lip portion 3 which is in close contact with the inner peripheral surface of the housing
Is provided with a tapered surface 4 whose diameter gradually increases from the pressure side A to the counter pressure side B. The tapered surface 4 is formed such that its diameter gradually increases from the pressure side A to the counter pressure side B, and as a result, it is inclined at a predetermined angle θ with respect to the center axis 0 of the packing 1, It also has a predetermined width w. The pressure side A and the counter pressure side B of the tapered surface 4 are arcuate surfaces 5, 6 respectively.
Is provided.

On the opposite pressure side B of the base 2, a lip 3
An annular anti-pressure side protruding portion 7 protruding on the anti-pressure side B from the base 3a of the lip portion 3 is integrally formed. A protruding annular pressure-side projection 8 is integrally formed. The inner peripheral surfaces of the base 2, the anti-pressure side protrusion 7, and the pressure side protrusion 8 are cylindrical surfaces 9 which are straight in the axial direction, and the cylindrical surface 9 has a pressure side A and a counter pressure side B, respectively. Arc-shaped surfaces 10 and 11 are provided.

When the packing 1 having the above structure is fitted on the outer periphery of the shaft 12, the structure shown in FIG. 2 is obtained. According to the packing 1, the following operation and effect can be obtained.

That is, when the packing 1 is mounted between the shaft 12 and a housing (not shown) and from the pressure side A to a location where positive pressure and negative pressure act alternately or randomly, first, When a positive pressure acts on the packing 1 from the pressure side A, the positive pressure presses the lip 3 so that the tip 3b of the lip 3 having the tapered surface 4 pierces the inner peripheral surface of the housing. Approach at a different angle.
Therefore, the contact force of the lip portion 3 with the inner peripheral surface of the housing increases, and the sliding resistance increases.
Is realized in a state in which it is not easily deformed, so that a necessary sealing property can be secured. Similarly, when a negative pressure acts on the packing 1 from the pressure side A instead of the positive pressure, the lip 3 is sucked by the negative pressure, and the tip 3b of the lip 3 is strongly applied to the inner peripheral surface of the housing. Pressed, which also ensures the necessary sealing properties. Therefore, even if the rigidity of the lip portion 3 is set low in order to absorb variations in the dimensional accuracy of the housing, the lip portion 3 is not easily deformed, and excellent sealing properties can be exhibited.

Further, since the opposite pressure side projection 7 is formed so as to protrude from the base 3a of the lip portion 3 to the opposite pressure side B, when a positive pressure is applied to the packing 1, the projection is formed. The part 7 serves as a support to suppress the rotation of the lip part 3,
The surface pressure of the lip 3 against the inner peripheral surface of the housing can be increased. Further, since the pressure side protrusion 8 is formed so as to protrude toward the pressure side A from the base 3a of the lip portion 3, even when a negative pressure is applied to the packing 1, the protrusion 8 serves as a support. As a result, the rotation of the lip portion 3 can be suppressed. Therefore, since the packing 1 is maintained in a stable posture and deformation of the lip portion 3 is suppressed, excellent sealing properties can be exhibited.

Second Embodiment FIG. 3 shows a half section of a packing 21 according to a second embodiment of the present invention, and the packing 21 is configured as follows. Incidentally, the packing 21 is a shaft (not shown, which is an inner peripheral side mounting member).
4) and a housing (not shown), which is a mating member on the outer peripheral side, and is a rubber-like elastic material which is mounted at a position where a positive pressure or a negative pressure acts from one axial direction (the lower part in the figure). Lip type packing. The outer peripheral surface of the shaft and the inner peripheral surface of the housing are each formed in a cylindrical shape straight in the axial direction.

The packing 1 has an annular base 22 fitted on the outer periphery of the shaft. A lip portion 23 is provided on the outer peripheral side of the base 22 in close contact with the inner peripheral surface of the shaft hole of the housing.
Are formed integrally, and the lip portion 23 extends from the base end portion 23a to the front end portion 23b on the pressure side (upper and lower sides in the figure).
From the upper side to the counter pressure side (upper side in the figure).

A lip portion 2 closely contacting the inner peripheral surface of the housing
3 has a cylindrical surface 24 that is straight in the axial direction.
And the cylindrical surface 24 has a predetermined width w. Arc-shaped surfaces 25 and 26 are provided on the pressure side A and the counter pressure side B of the cylindrical surface 24, respectively.

On the opposite pressure side B of the base 22, an annular opposite pressure side projection 27 projecting from the base 23a of the lip 23 toward the opposite pressure side B is integrally formed. An annular pressure-side projection 28 projecting more toward the pressure side A than the base 23a of the lip 23 is integrally formed. The inner peripheral surfaces of the base portion 22, the anti-pressure side protrusion 27, and the pressure side protrusion 28 are arranged such that
The tapered surface 29 is provided such that the diameter is gradually reduced from the pressure side A to the counter pressure side B. The packing 21 is inclined at a predetermined angle θ with respect to the center axis 0 of the packing 21. Pressure side A of this tapered surface 29
And the counter pressure side B are provided with arcuate surfaces 30, 31, respectively.

When the packing 21 having the above structure is fitted on the outer periphery of the shaft 32, the result is as shown in FIG. 4. According to the packing 21, the following operation and effect can be obtained.

That is, when the packing 21 is mounted between the shaft 32 and the housing (not shown) and from the pressure side A at a position where positive pressure and negative pressure act alternately or randomly, the base portion is 22, a taper portion 29 provided on the inner peripheral surface of the anti-pressure side protrusion 27 and the pressure side protrusion 28
The base 2 is deformed into a cylindrical shape following the outer peripheral surface of the base 2.
2. The anti-pressure side protrusion 27 and the pressure side protrusion 28 are deformed, the inclination angle of the lip 23 is changed accordingly, and the axially straight cylindrical surface provided at the tip 23b of the lip 23 24 deforms into a tapered surface shape whose diameter gradually increases from the pressure side A to the counter pressure side B, and the lip portion 23 comes into close contact with the shaft 32 in such a deformed posture.

When a positive pressure acts on the packing 21 in the deformed position from the pressure side A, the lip 23 is pressed by the positive pressure, and the lip 23 is deformed into a tapered cylindrical shape. The distal end 23b of the portion 23 enters at an angle such that it penetrates the inner peripheral surface of the housing.
Accordingly, the close contact force of the lip portion 23 with the inner peripheral surface of the housing increases, and the sliding resistance increases, thereby realizing a state in which the lip portion 23 is not easily deformed, thereby ensuring the necessary sealing performance. . When a negative pressure acts on the packing 21 instead of the positive pressure from the pressure side A, the lip portion 23 is sucked by the negative pressure,
The tip portion 23b of the lip portion 23 is strongly pressed against the inner peripheral surface of the housing, whereby the necessary sealing properties can also be ensured. Therefore, even if the rigidity of the lip portion 23 is set low in order to absorb variations in the dimensional accuracy of the housing, the lip portion 23 is not easily deformed, and excellent sealing properties can be exhibited.

Further, since the tapered surface 29 is provided on the inner peripheral surface of the base portion 22, the anti-pressure side protrusion 27 and the pressure side protrusion 28, the surface pressure of the packing 21 against the shaft 32 can be increased. it can. Also, the anti-pressure side protrusion 2
7 is formed so as to protrude from the base portion 23a of the lip portion 23 toward the counter pressure side B, so that when a positive pressure is applied to the packing 21, the protrusion 27 serves as a support and the lip portion The rotation of the lip 23 can be suppressed, and the surface pressure of the lip portion 23 against the inner peripheral surface of the housing can be increased. Further, since the pressure side protrusion 28 is formed so as to protrude toward the pressure side A from the base 23 a of the lip 23, even when a negative pressure acts on the packing 21, the protrusion 2
8 serves as a support, so that rotation of the lip portion 23 can be suppressed. Therefore, since the packing 21 is maintained in a stable posture and deformation of the lip portion 23 is suppressed,
Thereby, excellent sealing properties can be exhibited.

Third Embodiment In the second embodiment, a relatively large padding 2 is provided on the outer peripheral portion of the projection 28 in order to set the volume of the pressure side projection 28 large.
8a, the overfilling portion 28a may be relatively small like the packing 21 shown in FIG. 5 as the third embodiment. 23 is connected with a smooth curve. The other configuration, operation, and effect of the packing 21 in FIG. 5 are the same as those of the second embodiment, and thus description thereof is omitted.

The inventors of the present application have made the following considerations on the packing according to the present invention.

Relationship Between the Presence or Absence of the Tapered Surface 29 on the Inner Periphery of the Packing 21 and the Surface Pressure of the Lip 23 The packing 21 according to the second and third embodiments and FIG.
When the surface pressure distribution of the lip portion 23 at the time of the positive pressure action with the packing 21 according to the first comparative example shown in FIG. 7 was calculated, the packing 21 according to the second embodiment is FIG. 8, the packing 21 according to the first comparative example has obtained the results shown in the respective graphs of FIG. The packing 21 according to the first comparative example in FIG. 6 differs from the packing 21 according to the second and third embodiments in that the inner peripheral surface is a cylindrical surface that is straight in the axial direction. As you can see from this measurement result,
The surface pressure of the lip portion 23 is higher when the tapered surface 29 having the above configuration is provided on the inner peripheral surface of the packing 21 (second and third embodiments) than when the tapered surface is not provided (first comparative example). It turned out to be.

Relationship between the magnitude of the pressure side protrusion 28 and the deformed state at the time of the negative pressure action The packing 21 according to the second embodiment and the packing 21 according to the second comparative example shown in FIG. Looking at the deformed state, the packing 21 according to the second embodiment was in the posture shown in FIG. 11 and the packing 21 according to the second comparative example was in the posture shown in each of FIGS. The packing 21 according to the second comparative example of FIG. 10 has a volume (axial length) of the pressure side protrusion 28 which is slightly smaller than the packing 21 according to the second embodiment. As can be seen from this result, the larger volume of the pressure side protrusion 28 (second embodiment)
It was found that it was harder to deform than the smaller volume (second comparative example).

Relationship Between Size of Lip Base 28a and Deformation State at Maximum Compression The deformation state of the packing 21 according to the second embodiment and the packing 21 according to the third comparative example shown in FIG. As can be seen, the packing 21 according to the second embodiment was in the posture shown in FIG. 14 and the packing 21 according to the third comparative example was in the posture shown in each of FIGS. The packing 21 according to the third comparative example of FIG. 13 has a thickness of the base 23a of the lip 23 larger than that of the packing 21 according to the second embodiment. As can be seen from this result, if the thickness of the base portion 23a of the lip portion 23 is large, the lip portion 23 comes into contact with the non-pressure side projection 27, a large stress is locally generated in the bent portion 32, and the packing 21 It was found that it was easily damaged.

[0046]

The present invention has the following effects.

That is, in the packing according to the first aspect of the present invention having the above structure, the lip is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end to the tip end. In addition, since a tapered surface whose diameter gradually increases from the pressure side to the counter pressure side is provided at the tip of the lip portion, when a positive pressure acts on the packing from the pressure side, The lip is pressed by this positive pressure, and the tip of the lip having the tapered surface enters at an angle such that it penetrates the inner peripheral surface of the mating member. Therefore, the close contact force of the lip portion with the mating member increases, and the sliding resistance increases, so that a state in which the lip portion is not easily deformed is realized, and the necessary sealing property can be secured. When a negative pressure acts on the packing from the same pressure side, the negative pressure sucks the lip, and the tip of the lip is strongly pressed against the inner peripheral surface of the housing, thereby providing a necessary sealing property. Can be secured. Therefore, even if the rigidity of the lip portion is set low in order to absorb variations in the dimensional accuracy of the housing, the lip portion is not easily deformed, and excellent sealing properties can be exhibited.

Further, the present invention having the above-mentioned structure is described in claim 2 of the present invention.
In the packing according to the above, a projection is provided on the counter pressure side of the base, and a taper surface whose diameter is gradually reduced from the pressure side to the counter pressure side is provided on the inner peripheral surface of the base and the projection, and the lip is formed. Because it is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end to the tip end, and since the tip of the lip has a straight cylindrical surface in the axial direction, When the packing is fitted on the outer periphery of the mounting member, the base and the projection are deformed such that the tapered portion provided on the inner peripheral surface of the base and the projection is deformed into a cylindrical shape along the outer peripheral surface of the mounting member. The inclination angle of the lip changes accordingly, and the axially straight cylindrical surface provided at the tip of the lip gradually increases in diameter from the pressure side to the counter pressure side. Deformed like this. Lip portion is in close contact with the mating member in posture. Therefore, when a positive pressure acts on the packing in the deformed posture from the pressure side, the lip is pressed by the positive pressure, and the tip of the lip deformed into a tapered surface is brought into contact with the inner peripheral surface of the mating member. Enter at an angle that pierces the Therefore, the close contact force of the lip portion with the mating member increases, and the sliding resistance increases, so that a state in which the lip portion is not easily deformed is realized, and the necessary sealing property can be secured. Further, when a negative pressure acts on the packing from the same pressure side, the negative pressure sucks the lip, and the tip of the lip is strongly pressed against the inner peripheral surface of the mating member. Can be secured. Therefore, even if the rigidity of the lip portion is set low in order to absorb variations in the dimensional accuracy of the housing, the lip portion is not easily deformed, and excellent sealing properties can be exhibited.

Further, since the tapered surface is provided on the inner peripheral surface of the base and the protrusion, the surface pressure of the packing against the mounting member can be increased. Further, since the protrusion is formed so as to protrude from the base of the lip toward the counter pressure side, when a positive pressure is applied to the packing, the protrusion serves as a support, and the rotation of the lip is rotated. And the surface pressure of the lip against the inner peripheral surface of the housing can be increased. Therefore, excellent sealing properties can be exhibited from these facts.

Also, the present invention having the above-mentioned structure is characterized by claim 3
In the packing by the above, a counter pressure side protrusion is provided on the counter pressure side of the base, a pressure side protrusion is provided on the pressure side of the base, and an inner peripheral surface of the base, the counter pressure side protrusion and the pressure side protrusion is provided. A tapered surface is provided in which the diameter gradually decreases from the pressure side to the counter pressure side, and the lip is formed so that the lip is gradually inclined from the pressure side to the counter pressure side from the base end to the tip end. At the same time, since the tip of the lip is provided with a straight cylindrical surface in the axial direction, when the packing is fitted on the outer periphery of the mounting member, the inner portion of the base, the counter-pressure-side protrusion and the pressure-side protrusion is formed. The base, the counter-pressure-side protrusion and the pressure-side protrusion are deformed such that the tapered portion provided on the peripheral surface is deformed into a cylindrical surface along the outer peripheral surface of the mounting member,
The inclination angle of the lip changes accordingly, and the axially straight cylindrical surface provided at the tip of the lip becomes a tapered surface whose diameter gradually increases from the pressure side to the counter pressure side. It is deformed, and the lip portion comes into close contact with the mating member in the deformed posture. Therefore, when positive pressure acts on the packing in the deformed posture from the pressure side,
The lip is pressed by this positive pressure, and the tip of the lip deformed into a tapered surface enters at an angle such that it penetrates the inner peripheral surface of the mating member. Therefore, since the close contact force of the lip portion with the counterpart member is increased and the sliding resistance is increased, a state where the lip portion is hardly deformed is realized, and the necessary sealing property can be secured. Further, when a negative pressure acts on the packing from the same pressure side, the negative pressure sucks the lip, and the tip of the lip is strongly pressed against the inner peripheral surface of the mating member. Can be secured. Therefore, even if the rigidity of the lip portion is set low in order to absorb variations in the dimensional accuracy of the housing, the lip portion is not easily deformed, and excellent sealing properties can be exhibited.

Also, since the base portion, the non-pressure side protrusion and the pressure side protrusion have tapered surfaces on the inner peripheral surface,
Since the surface pressure of the packing against the mounting member can be increased, and since the opposite pressure side projection is formed so as to protrude more toward the opposite pressure side than the base of the lip portion, a positive pressure is applied to the packing. When acts, the projection serves as a support to suppress the rotation of the lip and increase the surface pressure of the lip against the mating member. Further, since the pressure side protrusion is formed so as to protrude more toward the pressure side than the base of the lip, even when a negative pressure is applied to the packing, the protrusion serves as a support, and the lip is formed. Rotation can be suppressed. Therefore, since the packing is maintained in a stable posture and the deformation of the lip portion is suppressed, excellent sealing performance can be exhibited.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a packing according to a first embodiment of the present invention.

FIG. 2 is a half cut sectional view of the packing fitted on a shaft.

FIG. 3 is a half sectional view of a packing according to a second embodiment of the present invention.

FIG. 4 is a half cut sectional view showing a state where the packing is fitted on a shaft.

FIG. 5 is a half sectional view of a packing according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a first comparative example.

FIG. 7 is a graph showing a lip surface pressure distribution of the packing according to the second embodiment.

FIG. 8 is a graph showing a lip surface pressure distribution of the packing according to the third embodiment.

FIG. 9 is a graph showing a lip surface pressure distribution according to a first comparative example;

FIG. 10 is a sectional view of a second comparative example.

FIG. 11 is a cross-sectional view showing a deformed state of the packing according to the second embodiment when a negative pressure is applied.

FIG. 12 is a cross-sectional view showing a deformed state of the second comparative example when a negative pressure is applied.

FIG. 13 is a sectional view of a third comparative example.

FIG. 14 is a cross-sectional view showing a deformation state of the packing according to the second embodiment at the time of maximum compression.

FIG. 15 is a sectional view showing a deformed state at the time of maximum compression of the third comparative example.

[Explanation of symbols]

1,21 packing 2,22 base 3,23 lip 3a, 23a root 3b, 23b tip 4,29 taper surface 5,6,10,11,25,26,30,31 arcuate surface 7,27 Pressure side protrusion 8, 28 Pressure side protrusion 9, 24 Cylindrical surface 12, 32 Shaft (mounting member) 28a Overlay 32 Bend 0 Central axis

Claims (3)

[Claims] 1. A packing (1) to be mounted between a mounting member on an inner peripheral side and a counterpart member on an outer peripheral side and to be applied with a positive pressure or a negative pressure from one side in an axial direction, wherein the mounting is performed. An annular base (2) made of a rubber-like elastic material fitted to the outer periphery of the member, and a lip (3) integrally formed on the outer periphery of the base (2) and in close contact with the mating member. The lip portion (3) is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end portion (3a) to the tip end portion (3b), and the lip portion (3) comes into close contact with the mating member. A packing characterized in that a tapered surface (4) whose diameter dimension gradually increases from the pressure side to the counter-pressure side is provided at a tip portion (3b) of the lip portion (3). 2. A packing (21) mounted between a mounting member on an inner peripheral side and a mating member on an outer peripheral side and applied to a position where a positive pressure or a negative pressure acts from one side in an axial direction, wherein the mounting is performed. An annular base portion (22) made of a rubber-like elastic material fitted to the outer periphery of the member; and a lip portion (2) integrally formed on the outer peripheral side of the base portion (22) and in close contact with the mating member.
3) and an annular projection (27) integrally formed on the counter pressure side of the base (22) and protruding from the base (23a) of the lip (23) on the counter pressure side. A taper surface (29) whose diameter is gradually reduced from the pressure side to the counter pressure side is provided on an inner peripheral surface of the base portion (22) and the protrusion portion (27); and the lip portion (23). Is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end (23a) to the tip end (23b), and the tip of the lip (23) closely contacting the counterpart member. (23b) A packing characterized in that an axially straight cylindrical surface (24) is provided in (23b). 3. A packing (21) mounted between a mounting member on an inner peripheral side and a counterpart member on an outer peripheral side and applied to a position where a positive pressure or a negative pressure acts from one side in the axial direction. An annular base portion (22) made of a rubber-like elastic material fitted to the outer periphery of the member; and a lip portion (2) integrally formed on the outer peripheral side of the base portion (22) and in close contact with the mating member.
3) and an annular counter-pressure-side protrusion (27) integrally formed on the counter-pressure side of the base (22) and protruding toward the counter-pressure side from the base (23a) of the lip (23).
And an annular pressure-side projection (28) integrally formed on the pressure side of the base (22) and projecting more toward the pressure side than the root (23a) of the lip (23). A tapered surface (29) whose diameter gradually decreases from the pressure side to the counter pressure side is formed on the inner peripheral surface of the base (22), the counter pressure side protrusion (27), and the pressure side protrusion (28). The lip portion (23) is formed so as to be gradually inclined from the pressure side to the counter pressure side from the base end portion (23a) to the tip end portion (23b), and is in close contact with the mating member. A packing characterized in that an axially straight cylindrical surface (24) is provided at a tip portion (23b) of the lip portion (23).