JP5801033B2 - Seal structure - Google Patents

Description

  The present invention relates to a seal ring and a seal device, and more particularly, to a seal ring and a seal ring used in a continuously variable transmission (hereinafter referred to as “CVT”) that changes a speed change steplessly by changing a diameter of a pulley. The present invention relates to a sealing device.

  In the hydraulic CVT, the groove width of the pulley is changed in correlation with the hydraulic pressure in the hydraulic chamber, and the speed change is continuously changed by changing the diameter of the pulley. Usually, a fixed pulley is integrally formed on a drive shaft, and a movable pulley is formed on a housing that reciprocates along this shaft. The movable pulley is provided with a hydraulic chamber. By controlling the hydraulic pressure of the hydraulic chamber, the movable pulley comes into contact with and is separated from the fixed pulley. As a result, the width of the groove formed in both pulleys is increased / decreased, the rotational radius of the belt wound around the pulleys is increased / decreased, power is transmitted, and the gear ratio is changed. A shaft ring formed on the outer peripheral surface of the shaft is fitted with a seal ring to fill the hydraulic chamber with oil and generate hydraulic pressure.

  In CVT, since a hydraulic pressure of about 7 MPa at maximum is generated in the hydraulic chamber, a seal ring having excellent wear resistance and sealing performance under high hydraulic pressure is required. In consideration of temperature rise due to heat generation during high-speed operation and use in cold regions, the seal ring is required to have resistance in a temperature range of −40 ° C. to 150 ° C. In general, as a seal ring material, a material in which an additive such as carbon powder or carbon fiber is filled in a fluorine-based resin such as polytetrafluoroethylene (PTFE), modified polytetrafluoroethylene, or ethylenetetrafluoroethylene (ETFE) is used. ing.

  In the CVT, since the oil pump is stopped when the engine is stopped, no hydraulic pressure is generated and no load is applied. In the conventional seal ring, a sufficient sealing performance can be obtained in a state where hydraulic pressure is generated. However, in a no-load state, the adhesion with the inner peripheral surface of the housing is lost, and the oil in the hydraulic chamber is drained. When the engine is restarted in such a state, it takes time until the hydraulic chamber is filled with oil. In addition, if the hydraulic chamber is started without being filled with oil, the rotating part of the CVT may be damaged due to seizure. Therefore, there is a need for a seal ring that can reduce oil leakage from the hydraulic chamber even when there is no hydraulic pressure and no load.

Conventionally, as a seal ring for CVT, as shown in FIG. 1, an endless type resin ring 7 having a substantially rectangular cross section and disposed on the outer peripheral side, and an O ring that is disposed on the inner peripheral side and gives expansion force to the resin ring. Combination seal rings made up of rings 6 have been used. In general, a PTFE resin or the like to which a filler is added is used as the material of the resin ring 7, and a rubber-like elastic body is used as the material of the O-ring 6.
In such a conventional combination seal ring, the O-ring 6 and the resin ring 7 are crushed and installed in the gap between the groove bottom 8 and the inner surface 4a of the housing 4. Assembling resistance is large when the shaft 3 to which is attached is inserted into the housing 4, and it is necessary to install the housing 4 by introducing a press-fitting device. For this reason, there is a problem in that the manufacturing cost increases, and it is impossible to detect an assembly failure of the seal ring.
Furthermore, since the conventional resin ring 7 does not have a joint, it has been necessary to extend the outer diameter of the ring to the shaft land portion 3b when inserting the shaft into the shaft groove 9. For this reason, it is necessary to reduce the outer diameter of the resin ring 7 to a predetermined outer diameter using a jig, and it takes time to assemble.
Further, in such a combined seal ring, since sliding resistance becomes high, sliding wear has been a problem particularly under high hydraulic pressure.

In response to the above-described problems, an endless type seal ring that can be easily mounted in a seal groove (shaft groove) with a smaller force has been proposed. Patent Document 1 shows a configuration in which a plurality of ridges extending in the axial direction are provided on an inner peripheral side of an annular body on a resin endless type seal ring, and the tips of these ridges are brought into contact with the bottom of the seal groove. Has been. By adopting the above-mentioned configuration, when getting over the groove edge of the seal groove, each protrusion provided on the inner peripheral side of the annular body is deformed so as to be tilted in the circumferential direction, and the endless type seal ring is made with a small force. It is described that it can be easily mounted in the seal groove.
Further, Patent Document 2 discloses a seal that is mounted in a seal groove provided on an outer diameter surface of a shaft that seals the inside of a housing, an outer peripheral portion is formed of a resin material, and an inner peripheral portion is formed of an elastic material. In the ring, a configuration is shown in which an inner peripheral portion formed of an elastic material is bitten inside the outer peripheral portion so that the outer peripheral portion formed of a resin material is thin. By adopting the above configuration, the cross-sectional area of the outer peripheral portion having a large deformation resistance against diameter expansion is reduced, and the cross-sectional area of the inner peripheral portion formed of an elastic material that is deformed flat and easily escapes is increased. The seal ring can be easily mounted in the seal groove with a small force.

  By adopting the configuration described in the above patent document, there is a possibility that the mounting to the seal groove is facilitated. However, since all of the above configurations are designed so that the inner peripheral surface of the seal ring is in contact with the groove bottom, the assembly resistance when inserting the shaft into the housing is large, and it is necessary to use a press-fitting device. With such a mounting method, the seal ring may be damaged or chipped. Further, a complicated shape like the seal ring of the above-mentioned patent document is generally formed by injection molding. In general, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyamide (PA) or the like is used as the resin for injection molding. However, these materials are harder and more brittle than conventional fluororesins such as PTFE. Therefore, when the structure in which the inner peripheral surface of the ring is in contact with the shaft groove bottom as described above is adopted, the seal ring is attached to the shaft. In some cases, breakage or chipping may occur.

JP 2008-190643 A JP 2008-190650 A

  The present invention has been made in view of the above circumstances, and can be easily attached to the shaft groove and the housing, has little sliding wear, and maintains close contact with the inner peripheral surface of the housing even in a no-load state where no hydraulic pressure is generated. It is an object of the present invention to provide a seal ring and a seal device that can be used.

As a result of diligent research in view of the above object, the present inventors have found that a resin ring that is mounted on a shaft groove formed on the outer peripheral surface of a shaft that moves relative to the housing and that is disposed on the outer peripheral side and has an abutment, In a seal ring having a coil expander disposed on the circumferential side, an inclined surface with an inclination angle of 45 ° to 75 ° is formed on the inner peripheral side of the pressure receiving side surface of the resin ring so that the axial width decreases toward the inner peripheral surface. The outer diameter of the free state in which the joint of the coil expander is provided and the outer diameter of the state in which the joint of the resin ring is closed is set to 0.92 to 0.98, even in a no-load state, The present invention has been completed by finding that the contact with the inner peripheral surface of the housing can be maintained, sliding wear can be kept low, and that it can be easily attached to the shaft groove and the housing. That is, the seal ring of the present invention is a seal ring that is attached to a shaft groove formed on the outer peripheral surface of a shaft that moves relative to the housing, and is disposed on the outer peripheral side and has a joint. A coil expander arranged on the circumferential side is provided, and an inclined surface with an inclination angle of 45 ° to 75 ° is provided on the inner peripheral side of the pressure receiving side surface of the resin ring so that the axial width decreases toward the inner peripheral surface, Further, the outer diameter of the free state in which the joint of the coil expander is closed is 0.92 to 0.98, where the outer diameter in the state of closing the joint of the resin ring is 1.
The sealing device of the present invention is a sealing device including the seal ring, wherein the outer diameter of the free state in which the joint of the coil expander is closed is set larger than the outer diameter of the shaft groove and smaller than the outer diameter of the shaft. It is characterized by being.

According to the seal ring of the present invention, even in a no-load state where no hydraulic pressure is generated, the outer peripheral surface of the resin ring disposed on the outer peripheral side is caused by the expansion force of the coil expander disposed on the inner peripheral side. Since it is in close contact with the inner peripheral surface, oil leakage from the hydraulic chamber can be prevented. In the seal ring of the present invention, since the resin ring has a joint, it can be easily mounted in the shaft groove. Furthermore, in the seal ring and the seal device of the present invention, since it is not necessary to crush at the time of mounting on the shaft groove, the shaft on which the seal ring is mounted can be easily assembled to the housing. Furthermore, in the seal ring of the present invention, the pressing force against the inner peripheral surface of the housing by the coil expander is maintained uniformly even under high temperature and high hydraulic pressure, so that the amount of sliding wear can be kept low.
Further, in the sealing device of the present invention, since the resin ring and the coil expander do not contact the bottom of the ring groove, excellent sealing performance can be maintained without deformation of the coil expander and the resin ring during operation. In the above configuration, there is an appropriate margin on the contact side of the resin ring and the wall surface of the shaft groove when the seal ring is mounted in the shaft groove. Easy to get. Furthermore, the sealing device having the above-described configuration has low sliding resistance and can suppress sliding wear even under high hydraulic pressure.

It is sectional drawing which shows the state with which the conventional seal ring was mounted | worn. It is sectional drawing which shows the state with which the seal ring of this invention was mounted | worn. It is a perspective view which shows an example of the joint shape of the resin ring of this invention (double angle joint). It is a perspective view which shows another example of the joint shape of the resin ring of this invention (double cut joint). It is a front view which shows an example of the coil expander of this invention. It is sectional drawing which shows the outline of a static leak performance test apparatus.

Hereinafter, a seal ring and a seal device of the present invention will be described in detail with reference to the drawings.
FIG. 2 shows an example of a mounting state of the seal ring of the present invention. The seal ring is attached to a shaft groove 9 provided on the outer peripheral surface of the shaft 3 installed on the inner periphery of the housing 4. A coil expander 1 is disposed on the groove bottom 8 side of the shaft groove, and a resin ring 2 is disposed on the housing 4 side. An inclined surface is provided on the inner peripheral side of the pressure receiving side surface (the side surface opposite to the contact side surface that contacts the shaft groove wall surface 3a) of the resin ring 2 so that the axial width decreases toward the inner peripheral surface. Here, the inclination angle of the inclined surface is set to 45 ° to 75 °. The inclination angle is θ in FIG. 2, and is an angle formed by the extended surface on the outer side of the pressure receiving side surface (surface not inclined) and the inclined surface. In addition, the outer diameter of the coil expander 1 when it is free, that is, the outer diameter in a state where both joints are closed and not bent is 0.92 to 0, where the outer diameter in the state where the joint of the resin ring 2 is closed is 1. .98. In the seal ring having the above-described configuration, the coil expander 1 is disposed between the inclined surface provided on the pressure receiving side surface of the resin ring 2 and the side surface of the shaft groove, and the outer peripheral surface of the resin ring 2 due to the tension of the coil expander 1. However, it is in close contact with the inner peripheral surface 4a of the housing 4 and exhibits sealing performance even in a no-load state.

  If the inclination angle is less than 45 °, not only excellent sealing performance can be obtained, but also the tension change due to the tolerance of the housing inner peripheral surface 4a becomes large. It becomes larger and the assembling property is lowered. Further, when the resin of the resin ring 2 is softened at a high temperature, if the inclination angle is small, the pressing force of the coil expander 1 against the inner peripheral surface of the housing becomes unstable, and the amount of sliding wear increases. On the other hand, even if the inclination angle is larger than 75 °, excellent sealing performance cannot be obtained. Furthermore, in this case, when the housing is inserted after the coil expander 1 and the resin ring 2 are mounted on the shaft 3, the coil expander 1 is likely to protrude from the resin ring 2, causing a problem in mounting properties. Further, if the inclination angle is large, the coil expander 1 is likely to move under high pressure, so that the pressing force of the resin ring 2 against the housing inner peripheral surface 4a becomes unstable, and the amount of sliding wear increases. In consideration of sealing properties, mounting (assembly) properties and sliding characteristics, the inclination angle is more preferably 55 ° to 65 °.

  If the outer diameter of the coil expander 1 when free is less than 0.92 with the outer diameter of the resin ring 2 in the closed state being less than 0.92, the coil expander 1 is less bent and the seal ring is likely to wobble. The sliding wear amount tends to increase, and the assembly becomes difficult. On the other hand, when the outer diameter of the coil expander 1 when free exceeds 0.98 with the outer diameter of the resin ring 2 in the closed state being 1, the assembly becomes difficult. In consideration of sliding characteristics and mountability, the outer diameter of the coil expander 1 when free is preferably 0.94 to 0.98, where the outer diameter of the resin ring 2 in the closed state is 1. .

Since the resin ring 2 of the present invention has an abutment and is excellent in mounting properties, the seal ring is crushed when mounted in the shaft groove like a conventional seal ring composed of an endless type resin ring and an O-ring. There is no need to include it. Therefore, it is not necessary to use a press-fitting device when mounting the shaft to the housing, and it can be easily mounted manually.
The shape of the joint of the resin ring 2 is not particularly limited. In addition to a right angle (straight) joint, an oblique (angle) joint, a stepped joint, a double angle joint shown in FIG. 3, a double cut joint shown in FIG. Can be adopted. A double angle joint and a double cut joint are preferable in order to block the oil flow to the joint gap and improve the sealing performance.
The material of the resin ring 2 is not particularly limited as long as it can withstand sliding under high hydraulic pressure, and fluorine such as polytetrafluoroethylene (PTFE), modified polytetrafluoroethylene, ethylenetetrafluoroethylene (ETFE), etc. In addition to the resin, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyimide (PI), etc. are used. In general, materials in which additives such as carbon powder and carbon fiber are dispersed in these resins are preferably used.

  The material of the coil expander 1 is not particularly limited, but is preferably manufactured using piano wire, stainless steel, silicon chrome steel or the like. Further, if both end faces 1a and 1b of the coil expander 1 are fixed so that the both end faces 1a and 1b are not separated by an external force, the assemblability of the seal ring is further improved. The fixing method of both end portions is not particularly limited, but it is preferable to insert a round wire 1c into the inner periphery of the coil expander 1 and crimp the end surfaces 1a and 1b of the coil expander 1 as shown in FIG. .

  In the sealing device of the present invention, it is preferable that the outer diameter of the free state in which the joint of the coil expander 1 is closed is set larger than the outer diameter of the shaft groove and smaller than the outer diameter of the shaft. In this configuration, the coil expander 1 is mounted between the inclined surface and the shaft groove wall surface and does not contact the groove bottom 8. Therefore, excellent sealability can be maintained without the coil expander 1 and the resin ring 2 being deformed during operation. Further, in the above-described configuration, there is an appropriate margin between the contact side surface of the resin ring 2 and the shaft groove wall surface 3a in a state where the seal ring is mounted in the shaft groove, and therefore, galling occurs when the shaft 3 is inserted into the housing 4. And excellent assemblability can be obtained. Furthermore, since the sealing device having the above configuration has low sliding resistance, it is possible to suppress wear during operation.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
(Example 1)
A resin ring was produced using PTFE resin containing 30% by mass of carbon fibers. Here, the outer diameter (nominal diameter) of the resin ring was 130 mm, the thickness (radial width) was 2.8 mm, and the width (axial width) was 3.1 mm. A single double angle joint shown in FIG. 3 is formed in the obtained resin ring, and the inclination angle θ is 45 on the inner peripheral side of one side surface (pressure receiving side surface) so that the axial width decreases toward the inner peripheral surface. An inclined surface of ° was formed. Further, a coil expander having a winding diameter of 1.6 mm and a tension of 2 N was produced using a piano wire having a wire diameter of 0.45 mm. At this time, the outer diameter in the free state with the joint of the coil expander closed was 0.95 when the outer diameter in the state with the joint of the resin ring closed was 1.

(Example 2)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 55 °.
(Example 3)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 60 °.
Example 4
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 65 °.
(Example 5)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 75 °.
(Comparative Example 1)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 40 °.
(Comparative Example 2)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 80 °.

(Measurement of oil leakage in a stationary state)
The coil expanders and resin rings of Examples 1 to 5 and Comparative Examples 1 and 2 are mounted on the shaft groove provided on the outer peripheral surface of the shaft as shown in FIG. 2, and the static leakage performance test apparatus shown in FIG. installed. About Example 1, it arrange | positioned so that the abutment of a resin ring may become an upper side and a lower side with respect to the centerline 18 of a test apparatus, and each oil leak amount was measured. Moreover, about Examples 2-5 and Comparative Examples 1 and 2, the amount of oil leak was measured about what arrange | positioned the joint in the lower side with respect to the centerline 18 of a testing apparatus. The hydraulic chamber 16 was filled with 165 cc of oil, and at room temperature (oil temperature: 25 ° C.), the oil leaked from the seal ring was recovered from the oil drain groove in a stationary state, and the cumulative amount of oil leakage for 7 days was measured. . Also, as a reference, without using a coil expander, a configuration in which only a resin ring similar to that in Example 1 is mounted (Reference Example 1) and an O-ring (1 type A) is disposed on the inner peripheral side, and an abutment is formed on the outer peripheral side. The static leakage performance test was similarly performed for the configuration (Reference Example 2) in which the inner ring surface of the O-ring was in contact with the groove bottom and the outer surface of the resin ring was in contact with the housing inner surface. went. The outer diameter of the shaft equipped with the seal ring is 160 mm, the outer diameter of the shaft groove is 145 mm, and the outer diameter (155 mm) in the free state with the joint of the coil expander closed is smaller than the outer diameter of the shaft. The outer diameter of the shaft groove was set larger.

  The results of measuring the static leakage amount are shown in Table 1. In Example 1, it was confirmed that sufficient static sealability was obtained when the abutment was arranged on either the upper side or the lower side. On the other hand, in Reference Example 1 in which no coil expander was installed, the cumulative amount of oil leakage for 7 days was 160 cc, and it was found that sufficient sealability could not be obtained in a no-load state. Moreover, from the results of Examples 1 to 5 and Comparative Examples 1 and 2, it was confirmed that excellent static sealing performance was obtained when the inclination angle of the resin ring was between 45 ° and 75 °. In addition, the amount of oil leakage of the comparative example 2 comprised from the resin ring without an O-ring and a joint was also comparable as Examples 1-5.

(Sliding resistance measurement)
The coil expander and the resin ring of Examples 1 to 5 were attached to the shaft groove provided on the outer peripheral surface of the shaft, and the housing was reciprocated at a stroke of 10 mm / s at an oil pressure of 1.5 MPa and an oil temperature of 80 ° C. The sliding resistance was measured. As a comparison, Comparative Examples 1 and 2 and Reference Examples 1 and 2 were also measured in the same manner as in Example 1.
The results of measuring the sliding resistance are shown in Table 1. Comparative Example 2 composed of an O-ring and a resin ring without a joint showed a very large sliding resistance of 2000 N, but the sliding resistance of Examples 1 to 5, Comparative Examples 1 and 2 and Reference Example 1 Almost no difference was observed.

(Measurement of sliding wear under high hydraulic pressure)
The coil expander and the resin ring of Examples 1 to 5 are mounted in the shaft groove provided on the outer peripheral surface of the shaft, and the housing is reciprocated 200 mm at a stroke of 10 mm / s at a hydraulic pressure of 4.0 MPa and an oil temperature of 150 ° C. The wear amount of the resin ring after moving was measured. As a comparison, Comparative Examples 1 and 2 and Reference Examples 1 and 2 were also measured in the same manner as in Example 1.
Table 1 shows the results of measurement of sliding wear under high hydraulic pressure. Compared with Reference Example 2, Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example 1 have a very small amount of sliding wear under high hydraulic pressure, and in particular, an inclination angle of 55 ° to 65 °. In Examples 2 to 4, it was confirmed that the amount of sliding wear was small. At this inclination angle, even if the resin of the resin ring is softened by heat, the pressing force against the housing inner peripheral surface by the coil expander is stably maintained, and the coil expander is maintained at a predetermined position even under high hydraulic pressure, It is thought that sliding wear was suppressed by the fact that the pressing force against the inner peripheral surface of the housing by the coil expander was stably maintained.

(Example 6)
A resin ring and a coil expander were produced in the same manner as in Example 1 except that the slope angle θ of the resin ring was 50 °.
(Example 7)
Resin ring and coil expander in the same manner as in Example 6 except that the outer diameter of the coil expander with the joint closed is 0.98, where the outer diameter of the resin ring with the joint closed is 1. Was made.
(Example 8)
Resin ring and coil expander in the same manner as in Example 6 except that the outer diameter in the free state with the joint of the coil expander closed is 0.92 with the outer diameter in the state of closing the joint of the resin ring being 1. Was made.
(Comparative Example 3)
Resin ring and coil expander in the same manner as in Example 6, except that the outer diameter in the free state with the joint of the coil expander closed is set to 1.00 with the outer diameter in the state of closing the joint of the resin ring being 1. Was made.

  In Comparative Example 3, since the coil expander protruded and proper assembly could not be performed, the static leakage amount, sliding resistance, and high hydraulic pressure of other Examples 6 to 8 were the same as in Example 1. The amount of sliding wear at the bottom was measured. The results are shown in Table 2. In any of the examples, the static oil leakage amount and the sliding wear amount under high hydraulic pressure were small, but the sliding wear amount under high hydraulic pressure was particularly small in Examples 6 and 7. This is considered to be due to the fact that the amount of deflection of the coil expander is optimized, so that a stable pressing force is applied to the inner peripheral surface of the housing without the seal ring fluctuating even under high hydraulic pressure.

1 Coil expander 2, 7 Resin ring 3 Shaft 4 Housing 6 O-ring

Claims (2)

A seal structure that is mounted in a shaft groove formed on an outer peripheral surface of a shaft that moves relative to a housing and that is used in a hydraulic chamber having a hydraulic pressure of 4.0 MPa or more;
A resin ring disposed on the outer peripheral side and having a joint; and a coil expander disposed on the inner peripheral side of the resin ring and spaced apart from the groove bottom of the shaft groove, and having a joint;
An inclined surface with an inclination angle of 50 ° to 65 ° is provided on the inner peripheral side of the pressure-receiving side surface of the resin ring so that the axial width decreases toward the inner peripheral surface,
The seal structure, wherein the coil expander is disposed along the inclined surface. The seal structure according to claim 1, wherein both the joints of the coil expander are fixed to each other.

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