JP2009058079A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant velocity universal joint achieving simultaneously the sealing performance of its boot and the permeability for suppressing an excessive deformation of the boot. <P>SOLUTION: The constant velocity universal joint is equipped with: an inner ring 1 coupled to a shaft 5; an outer ring 2 installed at the periphery of the inner ring 1; a plurality of balls 3 to make torque transmission between the inner ring 1 and the outer ring 2; and the boot 8 having a minor diametric end 8b and a major diametric end 8a, the former 8b being attached to the shaft 5 and the latter 8a being attached to one-end opening part of the outer ring 2 through a boot adapter 9. A tapered portion 8c2 of the boot 8 formed between the two ends 8b and 8a is furnished with an aeration hole 11, which is self-closed with an elastic deformation of the boot 8 generated when the joint rotates. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint used in, for example, a propeller shaft and a drive shaft of an automobile or various industrial machines.

  As is well known, in an FR vehicle, an engine, a clutch, a transmission (transmission) are arranged in the front, a reduction gear device (differential), and a driving axle are arranged in the rear, respectively, so that a propeller shaft is used for power transmission therebetween. It is customary. Further, the FR-based 4WD vehicle requires a rear propeller shaft and a front propeller shaft. These propeller shafts are equipped with constant velocity universal joints to accommodate changes in length and angle due to changes in relative position between the transmission and the differential.

  The constant velocity universal joint is formed of an outer ring, an inner ring coupled to a shaft, a torque transmission member (for example, a plurality of balls) that transmits torque between the outer ring and the inner ring, and an elastic material. And a boot having one end fitted (fixed) to the shaft.

  Among the above-described configurations, the boot is provided in order to prevent leakage of a lubricant (for example, grease) filled in the joint and to prevent foreign matter from entering from the outside of the joint.

  In order to prevent excessive deformation of the boot due to expansion deformation due to heat generated during rotation of the joint, the boot is usually provided with a vent hole, and the joint internal and external pressure is balanced through the vent hole. Secured.

  As this vent hole, for example, as disclosed in Patent Document 1 below, it is formed between the boot and the shaft so as to extend in the axial direction, or disclosed in Patent Document 2 below. As shown in the figure, there may be mentioned a lattice formed between the boot and the shaft.

  However, in such a configuration, the inside and outside of the joint are always communicated with each other through the vent hole, and therefore, the sealing performance itself that is originally required for the boot to prevent the leakage of the lubricant and the entry of the foreign matter may be impaired.

In view of this, there has been proposed one that employs a configuration that can open and close the vent hole as appropriate. Specifically, for example, Patent Document 3 below discloses that a fitting portion of a boot with a shaft is tightened from the outer peripheral side using an elastic band. With this configuration, when a centrifugal force exceeding a predetermined value is applied to the boot due to the rotation of the joint, the elastic band is extended so that the tightening force is weakened. Thereby, a gap (corresponding to a vent hole) corresponding to the amount of expansion of the elastic band is formed between the boot and the shaft.
Japanese Utility Model Publication No. 7-44969 JP 2006-275259 A Japanese Utility Model Publication No. 5-90053

  By the way, in the structure of said patent document 3, when a centrifugal force exceeding a predetermined value acts on the boot, that is, when the joint is rotating at a high speed, the vent hole is in a communicating state. However, when the joint is rotating at a high speed, a large centrifugal force acts on the lubricant filled in the joint. Therefore, if the vent hole is in communication, the centrifugal force causes lubrication from the vent hole. A situation may occur in which the agent is pushed out and leaks to the outside.

  Further, when the joint is rotating at a high speed, the amount of foreign matter scattered from the outside of the joint toward the boot increases accordingly. Therefore, if the vent hole is in communication with the joint at high speed, foreign matter may enter the joint through the vent hole.

  Therefore, in the configuration of Patent Document 3 in which the vent hole is in a communication state during high-speed rotation, the sealing performance of the boot is sufficiently ensured as in the configurations of Patent Documents 1 and 2 in which the vent hole is always in a communication state. Can not do it.

  In the above description, the constant velocity universal joint used for the propeller shaft has been described as an example, but the constant velocity universal joint used for the drive shaft and other various industrial machines is also formed with the above-described vent hole in the boot. If this is the case, similar problems may arise.

  In view of the above circumstances, an object of the present invention is to provide a constant velocity universal joint that can simultaneously achieve the sealability of a boot and the air permeability for suppressing excessive deformation of the boot.

  In order to solve the above-described problems, the present invention provides an inner member coupled to a shaft, an outer member disposed on the outer periphery of the inner member, and torque transmission between the inner member and the outer member. A torque transmission member for performing, a boot having a small-diameter end portion and a large-diameter end portion, the small-diameter end portion being attached to a shaft, and the large-diameter end portion being attached to one end opening of the outer member. In the constant velocity universal joint, an air passage is provided in the boot between the small-diameter end portion and the large-diameter end portion and elastically deformed when the joint rotates, and the air passage is used when the joint rotates. Characterized by self-closing by elastic deformation of boots.

  According to such a configuration, when the joint rotates at a low speed, the expansion deformation (elastic deformation) of the boot due to the centrifugal force does not substantially occur, and the air passage is in a communication state. As a result, even when heat is generated inside the joint due to rotation of the joint, heat can be released to the outside through the air passage, and a balance between the pressure inside and outside the joint is ensured. Therefore, a situation in which the joint is excessively deformed by heat generated during the low-speed rotation of the joint can be effectively suppressed. Further, in this state, since the centrifugal force acting on the lubricant is also small, it is possible to appropriately suppress a situation in which the lubricant leaks to the outside even when the air passage is in a communicating state. The same phenomenon applies when the joint is stopped.

  On the other hand, when the joint rotates at a high speed, the boot expands and deforms due to centrifugal force, but the amount of deformation is often uneven in the axial direction. For example, the amount of deformation may be different between the part near the boot attachment part (small diameter end part or large diameter end part) and the part far from it, and depending on the shape of the boot, the rigidity may differ in the axial direction. As a result, the amount of deformation may be different. Therefore, when the boot is inflated and deformed due to the difference in deformation amount in the axial direction, the air passage can be self-closed with elastic deformation. Here, the term “self-closing” means that the ventilation path is not closed by another member but is closed by deformation of the boot itself.

  In this manner, by closing the air passage that has been in a communicating state when the joint rotates at high speed, it is possible to reliably prevent a situation in which the lubricant leaks to the outside through the air passage due to centrifugal force. When the joint moves from this state to the stopped state, the centrifugal force acting on the boot decreases, and the amount of deformation of the boot decreases due to the elastic restoring force of the boot. As a result, the closed air passage is reopened. Thereby, the heat generated during the high-speed rotation of the joint can be released to the outside through the air passage during the low-speed rotation in which the number of rotations is lower than that during the high-speed rotation. Therefore, a situation in which the joint is excessively deformed by heat generated during high-speed rotation of the joint can be effectively suppressed.

  In addition, since the ventilation path is closed when the boot rotates at high speed, it is possible to reliably prevent the entry of foreign matter in this state. And since the amount of foreign matter scattering to the boot decreases as the rotational speed of the joint decreases, even when the air passage becomes a communication state, the foreign matter enters through the air passage. Can be suppressed appropriately.

  In the above configuration, the boot includes a folded portion provided between the small diameter portion and the large diameter portion, and a tapered portion that gradually expands from the small diameter portion and reaches the folded portion, It is preferable to provide an air passage in the tapered portion.

  In such a boot, the tapered portion is a portion that is elastically deformed when the joint rotates. Therefore, by providing an air passage in such a taper portion, the self-closing action of the air passage can be reliably obtained.

  Said structure WHEREIN: It is preferable to seal the other end opening part of the said outer member with a seal plate, and to provide the ventilation cap which has air permeability in the center part of this seal plate.

  In this way, even if the ventilation path of the boot is closed during high-speed rotation of the joint, the ventilation cap supplementarily secures the air permeability inside the joint, thus preventing excessive deformation of the boot. This is advantageous.

  Said structure WHEREIN: It is preferable that the said boot is formed with the rubber material.

  The constant velocity universal joint having the above-described configuration may be a bar field type fixed constant velocity universal joint.

  The constant velocity universal joint having the above-described configuration can be suitably used for a propeller shaft.

  That is, in the constant velocity universal joint for the propeller shaft, since the high speed rotation operation is required, the above-described configuration capable of reliably preventing the leakage of the lubricant by closing the air passage during the high speed rotation is extremely useful. It becomes.

  As described above, according to the present invention, when the joint is rotated at a high speed, the air passage is closed by the centrifugal force acting by the rotation, so that both leakage of the lubricant due to the centrifugal force and entry of foreign matters are surely prevented. can do. Therefore, it is possible to reliably ensure the sheet properties of the boot when the joint rotates at high speed.

  In addition, when the joint is stopped or rotated at a low speed, the air passage is in communication, so heat generated during high-speed rotation can be released to the outside of the joint through the air passage. Can be secured. Therefore, excessive deformation of the boot can be suitably suppressed.

  Furthermore, when the joint is stopped or rotated at a low speed, the situation where the lubricant leaks due to centrifugal force or foreign matter enters is extremely less than at the time of high speed rotation. In addition, it is possible to appropriately ensure the sealability of the boot.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 illustrates an embodiment of the present invention, which is applied to a barfield type fixed constant velocity universal joint (BJ). The present invention is not limited to this bar field type constant velocity universal joint, and includes, for example, a sliding type constant velocity universal joint such as a double offset type constant velocity universal joint (DOJ) and other fixed type constant velocity universal joints. It is widely applicable to all constant velocity universal joints that can be used for propeller shafts.

  This Barfield type constant velocity universal joint includes an inner ring 1 and an outer ring 2 as inner members, a plurality of balls 3 as torque transmission members, and a cage 4 as main components. In this embodiment, the outer member is constituted by the outer ring 2 and a boot adapter 9 described later.

  The inner ring 1 has a plurality of track grooves 1a formed on the outer peripheral surface (outer spherical surface) thereof. By forming the spline 1b on the inner diameter of the center hole of the inner ring 1 and forming the spline 5b on the outer diameter of the shaft part 5a of the shaft 5, the shaft part 5a of the shaft 5 is inserted into the center hole of the inner ring 1. It is connected by spline fitting to enable torque transmission between the two. A ring groove 5 c is provided at the tip of the shaft portion 5 a of the shaft 5, and the shaft 5 is attached to the inner ring 1 by locking the snap ring 6 attached to the ring groove 5 c at the end surface of the inner ring 1. It has been retained.

  The outer ring 2 is disposed on the outer periphery of the inner ring 1, and the same number of track grooves 2 a as the track grooves 1 a of the inner ring 1 are formed on the inner peripheral surface (inner spherical surface) thereof. The track groove 1a of the inner ring 1 and the track groove 2a of the outer ring 2 form an angle inclined in the opposite direction with respect to the axis, and a ball is formed at the intersection of the pair of the track groove 1a of the inner ring 1 and the track groove 2a of the outer ring 2 3 is incorporated. A cage 4 is disposed between the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2, and the ball 3 is held in a pocket 4 a of the cage 4 so as to roll freely.

  A seal plate 7 having a ventilation cap (air breather) 7a at one end opening of the outer ring 2 in order to prevent leakage of lubricant (for example, grease) filled in the joint and to prevent foreign matter from entering from the outside of the joint. Are fixed by bolting, and a boot 8 is mounted between the other end opening of the outer ring 2 and the shaft 5 via a metal boot adapter 9.

  The ventilation cap 7 a is made of an elastic material such as rubber, and is fitted and fixed in a state of being inserted into a through hole formed at the center of the seal plate 7. The ventilation cap 7a is provided with a slit configured to be openable and closable (not shown).

  The boot 8 has a large-diameter end portion 8a, a small-diameter end portion 8b, and an intermediate portion 8c that connects the large-diameter end portion 8a and the small-diameter end portion 8b. And this intermediate part 8c has the folding | returning part 8c1, and the taper part 8c2 which reaches the folding | returning part 8c1, expanding gradually from the small diameter edge part 8b. The boot adapter 9 has a cylindrical shape, has a flange 9 a fitted to the outer peripheral surface of the outer ring 2 at one end, and is fixed to the outer ring 2 by bolting together with the seal plate 7. A small-diameter end 8 b of the boot 8 is attached to the shaft 5 and fastened with a boot band 10. The large-diameter end portion 8 a of the boot 8 is held by crimping the end portion 9 b of the boot adapter 9.

  The boot 8 is made of an elastic material such as a rubber material or a resin material, and is, for example, an ester-based, olefin-based, urethane-based, amide-based, styrene-based thermoplastic elastomer, or a compression set more than the thermoplastic elastomer. A rubber material such as CR, NBR, silicon, fluorine rubber, or chloroprene having a small C is preferable. The thermoplastic elastomer described above is excellent in durability, such as fatigue and wear, heat aging resistance, oil resistance, and high-speed rotation (running performance during rotation) as a material of the boot 8 and exhibits a stable function.

  An annular recess 5 d is formed on the outer peripheral surface of the shaft 5, and the small-diameter end portion 8 b of the boot 8 is fitted on the annular recess 5 d and is fastened by the boot band 10. The small-diameter end portion 8b is formed of a thick cylindrical portion, and its inner diameter is set to be slightly smaller than the outer diameter of the annular recess 5d in a free state, thereby ensuring the fit to the annular recess 5d. . Further, a circumferential groove 8d is formed on the outer peripheral surface of the small diameter end portion 8b, and the boot band 10 is fitted in the circumferential groove 8d.

  The boot 8 configured as described above is provided with a vent hole (vent passage) 11 in order to prevent excessive deformation of the boot 8 due to internal pressure expansion due to heat during high-speed rotation. The ventilation hole 11 is formed in the taper portion 8c2 of the boot 8 as shown in an enlarged view in FIG.

  In this embodiment, when the boot 8 expands to the outer diameter side due to the centrifugal force acting when the joint rotates, the opening 11 a on the joint inner side of the vent hole 11 is closed by the expansion deformation of the boot 8. I am doing so.

  That is, as shown in FIG. 2, when the joint is stopped or rotated at a low speed (for example, 4000 to 5000 rpm or less), the boot 8 is not substantially expanded and deformed by the centrifugal force, and the vent hole 11 is in a communicating state. Thereby, the air permeability inside and outside the joint is ensured through the vent hole 11 in the communication state, and excessive deformation of the boot 8 due to internal pressure expansion can be prevented in advance. Further, in this state, the centrifugal force itself does not act on the lubricant, or even if it acts, it is small. Therefore, even when the vent hole 11 is in communication, it is difficult for the lubricant to leak through the vent hole 11. . Further, with respect to the entry of foreign matter, the amount of foreign matter scattered to the boot 8 itself is small when the joint is stopped and when rotating at a low speed, so that the situation of foreign matter entering through the vent hole 11 is reduced. Therefore, the sealing performance of the boot 8 can be sufficiently exhibited.

  On the other hand, when the joint rotates at a high speed (for example, 8000 to 1000 rpm or more), as shown in FIG. 3, the taper portion 8c2 of the boot 8 is expanded and deformed to the outer diameter side due to the centrifugal force accompanying the rotation, and is in a communicating state. The opening 11a inside the joint of the vent hole 11 is closed. Therefore, even when the lubricant moves so as to be pressed against the inner surface of the boot 8 by a large centrifugal force acting at high speed rotation, it is possible to reliably prevent such a lubricant from leaking to the outside through the vent hole 11. Can do. Further, the entry of foreign matter can be reliably prevented since the vent hole 11 is closed. Therefore, the sealing performance of the boot 8 can be maintained.

  In addition, the reason why the vent hole 11 of the boot 8 is closed by the above-described expansion deformation is as follows. The amount of expansion deformation due to the centrifugal force of the boot 8 is often non-uniform in the axial direction. For example, the amount of deformation may be different between a portion near the mounting portion (the large diameter end portion 8a and the small diameter end portion 8b) of the boot 8 and a portion far from the mounting portion, and depending on the shape of the boot 8, its rigidity may be in the axial direction. As a result, the amount of deformation may be different. Therefore, when the boot 8 is inflated and deformed due to the difference in deformation amount in the axial direction, the vent hole 11 is closed with elastic deformation.

  Then, when the joint is stopped from such a high speed rotation state, the opening 11a on the inside of the joint of the closed vent hole 11 is opened again, and the heat generated during the high speed rotation of the joint also causes the vent hole 11 to pass through. It can escape efficiently to the outside. Therefore, it is possible to effectively suppress the situation in which the boot 8 is excessively deformed by heat generated during high-speed rotation of the joint.

  Further, in this embodiment, even if the vent hole 11 is closed during high-speed rotation, the air permeability is supplementarily secured by the slit provided in the vent cap 7a fitted to the seal plate 7. It has become. More specifically, when the gas inside the joint expands, the slit of the vent cap 7a opens according to the amount of expansion. The slit is designed to ensure breathability. Here, since the ventilation cap 7a is arranged at the center of rotation, even if the slit is opened during high-speed rotation, the lubricant pressed against the outer diameter side by centrifugal force leaks from the slit. Cannot occur substantially. Further, since the seal plate 7 is usually mounted in a state of being accommodated in the internal space of the companion flange, the rate of foreign matter entering from the slit of the ventilation cap 7a is very small.

  In addition, this invention is not limited to said embodiment at all, In the range which does not deviate from the summary of this invention, it can implement with a various form. For example, as shown in FIG. 4A, the vent hole 11 may be formed in a tapered shape so that the opening area is gradually reduced from the joint inner side toward the joint outer side. At this time, the inclination angle of the taper is adjusted so that the opening outside the joint of the vent hole 11 is closed when the joint is stopped. In this manner, as shown in FIG. 4A, when the joint is stopped or rotated at a low speed (for example, 5000 rpm or less), the boot 8 is not substantially deformed due to centrifugal force, and the vent hole 11 The opening 11a inside the joint is maintained in a closed state. And if the rotation speed of a joint increases from this state and enters into a medium-speed rotation area | region (for example, the range of 5000-8000 rpm), as shown in FIG.4 (b), the taper part of the boot 8 with the centrifugal force accompanying the rotation will be shown. 8c2 expands and deforms to the outer diameter side, and the opening 11a on the inner side of the joint of the vent hole 11 in the closed state is opened. Further, when the rotation of the joint increases and enters a high-speed rotation region (for example, 8000 rpm or more), the centrifugal force accompanying the rotation further increases, and the taper portion 8c2 of the boot 8 expands and deforms to the outer diameter side, and the air hole 11 The opening 11b on the outer side of the joint is closed. On the other hand, when the rotational speed decreases from the high-speed rotation region, the opening 11b on the outside of the joint of the vent hole 11 opens, and then the opening 11a on the inside of the joint of the vent hole 11 is closed. The Thereby, since the vent hole 11 is closed even when the joint is stopped or rotated at a low speed, it is possible to further reduce the rate at which foreign matter enters the vent hole 11. At the same time, the heat generated during the high-speed rotation of the joint can be released to the outside at this time because the vent hole 11 is in a communicating state during the medium-speed rotation of the joint.

  The shape of the vent hole 11 is not particularly limited, and may be a circle or a slit extending along the circumferential direction.

  Further, the air holes 11 may be provided only at one place of the boot 8 or may be provided at a plurality of places intermittently in the circumferential direction of the boot 8.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view schematically showing an overall configuration of a barfield type constant velocity universal joint according to an embodiment of the present invention. FIG. 2 is an enlarged vertical sectional view of a main part schematically showing a state of a boot when the constant velocity universal joint of FIG. 1 is stopped or rotated at a low speed. FIG. 2 is an enlarged vertical cross-sectional view of a main part schematically showing a state of a boot during high-speed rotation of the constant velocity universal joint of FIG. 1. (A) is an enlarged vertical sectional view of a main part around a boot schematically showing a modification of the present embodiment, and (b) is a main part schematically showing a state of the boot at the middle speed rotation of the constant velocity universal joint. An enlarged longitudinal sectional view, (c) is an enlarged longitudinal sectional view of an essential part schematically showing the state of the boot when the constant velocity universal joint is rotated at a high speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Track groove 2 Outer ring 2a Track groove 3 Ball 4 Cage 5 Shaft 8 Boot 8a Large diameter end 8b Small diameter end 8c Intermediate part 8c1 Folded part 8c2 Tapered part 11 Vent

Claims (6)

An inner member coupled to the shaft, an outer member disposed on an outer periphery of the inner member, a torque transmitting member that transmits torque between the inner member and the outer member, a small-diameter end portion, and a large-diameter end portion In the constant velocity universal joint, the small diameter end portion is attached to the shaft, and the large diameter end portion includes a boot attached to one end opening of the outer member.
A vent path is provided between the small-diameter end portion and the large-diameter end portion of the boot and elastically deformed when the joint rotates, and the vent path is self-closed by elastic deformation of the boot when the joint rotates. A constant velocity universal joint characterized in that   The boot includes a folded portion provided between the small-diameter portion and the large-diameter portion, and a tapered portion that gradually expands from the small-diameter portion to reach the folded portion. The constant velocity universal joint according to claim 1, wherein the constant velocity universal joint is provided at a portion.   The constant velocity universal joint according to claim 1 or 2, wherein the other end opening of the outer member is sealed with a seal plate, and a ventilation cap having air permeability is provided at the center of the seal plate.   The constant velocity universal joint according to claim 1, wherein the boot is made of a rubber material.   The constant velocity universal joint according to any one of claims 1 to 4, wherein the constant velocity universal joint is a barfield type fixed constant velocity universal joint.   It is used for a propeller shaft, The constant velocity universal joint in any one of Claims 1-5 characterized by the above-mentioned.

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