JP2009079689A - Propeller shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide permeability capable of suppressing excessive deformation of boots in an internal space while securing sealability of the joint internal space. <P>SOLUTION: A propeller shaft is provided with: a constant velocity universal joint 4 carrying out torque transmission via a plurality of balls 7 between an inner ring 5 and an outer ring 6; a stub shaft 2 with a tip coupled to the inner ring 5; a hollow shaft 3 connected to a base end part of the stub shaft 2; the boots 12 blocking off a space X1 of an axial one end side of the outer ring 6 from which the stub shaft 2 protrudes; and a companion flange 14 blocking off a space X2 of an axial another end side of the outer ring 6. A vent hole 15 communicating the joint internal space X sealed by the boots 12 and the companion flange 14 with an internal space Y of the hollow shaft 3 is provided in the stub shaft 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a propeller shaft.

  In an FR vehicle, an engine, a clutch, a transmission (transmission) are arranged at the front, a reduction gear device (differential), and a drive axle are arranged at the rear. . Further, the FR-based 4WD vehicle requires a rear propeller shaft and a front propeller shaft. In recent years, as a power transmission shaft of these propeller shafts, a structure in which a hollow shaft is connected to a base end portion of a solid stub shaft is widely used from the viewpoint of weight reduction and the like. Furthermore, a constant velocity universal joint is coupled to the distal end portion of the stub shaft in order to cope with a change in length and angle due to a relative position change between the transmission and the differential.

  This type of constant velocity universal joint includes an inner ring, an outer ring, and a plurality of balls that transmit torque between the inner ring and the outer ring, and a stub shaft is coupled to the inner ring.

  Then, one end in the axial direction of the outer ring from which the stub shaft protrudes is closed by the boot, and the other end in the axial direction of the outer ring is closed by the seal plate. Thus, by sealing the joint internal space, leakage of grease filled in the joint internal space and entry of foreign matter from the outside are prevented.

  A companion flange is fixed to the other end in the axial direction of the outer ring so that the seal plate is accommodated therein, and an output shaft or a differential input shaft of the transmission is coupled to the companion flange.

  However, in a constant velocity universal joint used for a propeller shaft, since power transmission at high speed rotation is required, a large amount of heat is generated during rotation. Therefore, there is a problem that the gas in the joint internal space expands due to the temperature rise and the boot is excessively deformed.

  Therefore, from the viewpoint of preventing such excessive deformation of the boot, in order to ensure the air permeability of the joint inner space sealed by the boot and the seal plate, an air passage is formed in the boot, or an air passage is provided in the seal plate. What has been formed is proposed.

  The air flow path of the former boot is formed between the groove and the outer peripheral surface of the stub shaft by providing a groove on the inner peripheral surface of the boot end, for example (Patent Document 1). When the gas in the joint internal space expands, the expanded gas is directly discharged to the outside of the boot, that is, outside air, through the air passage.

The air passage of the latter seal plate is formed, for example, by covering a through hole provided in the center of the seal plate with an elastic member and providing a slit that can be opened and closed in the elastic member (Patent Document 2). When the gas in the joint internal space expands, the air passage (slit) opens, and is formed between the internal space of the companion flange that fixes the expanded gas to the outer ring, specifically between the companion flange and the seal plate. It is designed to be discharged into a space.
Japanese Utility Model Publication No. 7-44969 Japanese Patent Laid-Open No. 9-72351

  In the above-described configuration in which the ventilation path is formed in the boot, the range of the ventilation path is limited to the end portion of the boot, so that the path length of the ventilation path is inevitably shortened. Therefore, the grease inside the joint is likely to leak through the air passage. In addition, since one end of the air passage is directly open to the outside air, foreign matter (especially external moisture) easily enters from the outside in the air passage having a short passage length. Therefore, there is a problem that the sealing performance of the joint internal space cannot be sufficiently secured.

  On the other hand, in the configuration in which the air passage is formed in the seal plate, one end of the air passage is open to the space between the companion flange and the seal plate. The penetration rate of foreign matter can be reduced as compared with the case where one end is directly open to the outside air.

  However, even in this case, the formation range of the vent path of the seal plate is limited to a slight range corresponding to the thickness of the elastic member covering the through hole of the seal plate, and therefore the path length is inevitably short. Become. Therefore, leakage of grease can occur through the air passage. Therefore, there exists a problem that the sealing performance of the joint internal space cannot be ensured accurately.

  In addition, the internal space of the companion flange is usually limited to the minimum necessary volume from the viewpoint of compactness. Therefore, the space between the companion flange and the seal plate cannot be made so large, and the volume of the space is smaller than the joint internal space. As a result, when the gas in the joint internal space expands, the expanded gas cannot be sufficiently absorbed in the space between the companion flange and the seal plate. Therefore, the gas expanded through the air passage cannot be effectively discharged, and the boot may be excessively deformed.

  In order to cope with such a situation, it is conceivable to separately provide a communication hole communicating with the outside air in the companion flange, but in this case, foreign matter enters the inside of the companion flange from the outside. For this reason, as in the case where the air passage is formed in the boot, the rate of foreign matter entering through the air passage increases. Therefore, it cannot be an effective measure to ensure the sealing performance of the joint internal space.

  In view of the above circumstances, an object of the present invention is to provide air permeability capable of suppressing excessive deformation of the boot to the internal space while ensuring the sealability of the joint internal space.

  The present invention, which was devised to solve the above-described problems, includes a constant velocity universal joint that transmits torque via an torque transmission member between an inner joint member and an outer joint member, and torque between the inner joint member. A propeller shaft comprising a hollow shaft for transmitting, a boot for closing one opening of the outer joint member, and a sealing member for closing the other opening of the outer joint member. The joint internal space sealed by the stop member is characterized in that it communicates with the internal space of the hollow shaft through the air passage.

  According to such a configuration, the joint internal space sealed by the boot and the sealing member and the internal space of the hollow shaft communicate with each other through the air passage, so that the gas pressure inside the joint increases due to heat generation during rotation. Even in such a case, the gas in the joint inner space can be released to the inner space of the hollow shaft through the air passage. And since the internal space of this hollow shaft has a sufficiently large volume compared with the joint internal space, even when the other opening of the hollow shaft is sealed by another constant velocity universal joint or the like, The volume increase due to the discharged gas can be absorbed in the internal space of the hollow shaft.

  Further, by providing the air passage so that the joint internal space and the internal space of the hollow shaft communicate with each other, the length of the air passage can be made longer than when the air passage is provided at the boot end or the like. Therefore, the situation where grease leaks through the air passage can be effectively suppressed. In addition, both the joint internal space and the hollow shaft internal space are sealed spaces, and the sealed spaces are communicated with each other by a ventilation path, so that the sealed space is maintained as a whole without directly communicating with the outside air. Therefore, it is possible to reliably suppress a situation in which foreign matter enters the joint internal space from the outside.

  Said structure WHEREIN: It is preferable to provide the said ventilation path in the stub shaft by which one end was connected with the said inner joint member, and the other end was connected with the said hollow shaft outside the said boot.

  In this way, it is possible to easily form an air passage having a long path extending to the outside of the boot, which is advantageous in preventing leakage of grease in the joint inner space.

  Said structure WHEREIN: It is preferable to provide the said ventilation path on the axial center of the said stub shaft.

  In this case, the grease filled in the joint inner space moves to the outer diameter side due to the centrifugal force acting at the time of rotation, so that the grease leaks from the air passage provided on the shaft center of the stub shaft. Can be more reliably suppressed.

  In the above-described configuration, it is preferable that a resistance imparting member that can ventilate and impart outflow resistance to the grease is disposed in the opening on the joint inner space side of the vent passage.

  If it does in this way, the ratio itself in which grease penetrate | invades in a ventilation path from the opening part by the side of the joint interior space of a ventilation path can be suppressed effectively, maintaining the air permeability of a ventilation path.

  In this case, the resistance applying member may be formed of a seal plate having a through hole.

  That is, for example, by making the opening area of the through hole of the seal plate smaller than the opening area of the air passage with respect to the joint internal space, the seal plate functions as an effective resistance imparting member, and the leakage of grease is more reliably ensured. Can be suppressed.

  The resistance applying member may be formed of an elastic body having a slit.

  In this way, only when the gas in the joint internal space is expanded, the slit is opened by the expansion of the gas, so that leakage of grease can be more reliably suppressed.

  As described above, according to the present invention, the joint internal space sealed by the boot and the sealing member and the internal space of the hollow shaft are communicated by the air passage, so that the gas pressure inside the joint is generated by heat generated during rotation. Even in the case of increasing the gas, the gas in the joint inner space can be released to the inner space of the hollow shaft through the air passage. And since the internal space of this hollow shaft has a sufficiently large volume compared with the joint internal space, the volume increase by the gas discharged | emitted through a ventilation path can be absorbed in the internal space of a hollow shaft. Therefore, the air permeability of the joint internal space can be sufficiently ensured, and the excessive deformation of the boot due to the gas expansion in the joint internal space can be reliably prevented.

  Also, by providing the air passage so that the joint internal space and the internal space of the hollow shaft communicate with each other, the length of the air passage can be made longer than when the air passage is provided at the end of the boot, etc. The situation where grease leaks through the road can be effectively suppressed. Moreover, since the air passage is not in direct communication with the outside air, it is possible to reliably prevent foreign matter from entering the joint internal space from the outside. Therefore, the sealing performance inside the joint can be effectively ensured.

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

  FIG. 1 is a longitudinal sectional view showing a propeller shaft according to a first embodiment of the present invention. As shown in the figure, this propeller shaft includes a stub shaft 2 as a power transmission shaft 1 and a hollow shaft 3 connected and fixed to a large-diameter portion 2 a formed at the base end portion of the stub shaft 2. A constant velocity universal joint 4 is coupled to the distal end portion of the stub shaft 2.

  The constant velocity universal joint 4 includes an inner ring 5 as an inner joint member, an outer ring 6 as an outer joint member, a plurality of balls 7 as torque transmission members, and a cage 8 as main components.

  The inner ring 5 has a plurality of track grooves 5a formed on the outer peripheral surface thereof. The shaft portion 2b of the stub shaft 2 is inserted into the center hole of the inner ring 5, and both are connected by spline fitting to enable torque transmission. The stub shaft 2 is prevented from coming off from the inner ring 5 by a snap ring 9.

  The outer ring 6 is disposed on the outer periphery of the inner ring 5, and the same number of track grooves 6a as the track grooves 5a of the inner ring 5 are formed on the inner peripheral surface thereof. The track groove 5a of the inner ring 5 and the track groove 6a of the outer ring 6 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 5a of the inner ring 5 and the track groove 6a of the outer ring 6 7 is incorporated. A cage 8 is disposed between the outer peripheral surface of the inner ring 5 and the inner peripheral surface of the outer ring 6, and the balls 7 are held in a pocket 8 a of the cage 8 so as to be able to roll.

  A flange 10 a provided at the base end portion of the metal boot adapter 10 is fixed to one end in the axial direction (one opening side end portion) of the outer ring 6 by a bolt 11. A boot 12 made of an elastic member is disposed so as to seal between the tip of the boot adapter 10 and the stub shaft 2. The boot 12 has a small-diameter portion 12a and a large-diameter portion 12b, and has a shape that is folded in a U-shape in the middle. The small diameter portion 12 a of the boot 12 is attached to the stub shaft 2 and fastened with a boot band 13. The large-diameter portion 12b of the boot 12 is held by crimping the end portion of the boot adapter 10.

  On the other hand, a hollow companion flange 14 whose inner wall surface 14 a is closed is fixed to the other end in the axial direction of the outer ring 6 (the other opening side end) by a bolt 11. The companion flange 14 is fixed to the output shaft of the transmission or the differential input shaft.

  In this manner, the joint internal space X filled with grease is sealed by closing the spaces X1 and X2 on both axial ends of the outer ring 6 with the boot 12 and the companion flange 14 (sealing member). .

  The stub shaft 2 is formed with a vent hole 15 that communicates the sealed joint internal space X and the internal space Y of the hollow shaft 3. The vent hole 15 is formed on the axial center of the stub shaft 2, one end of which opens into the internal space Y of the hollow shaft 3, and the other end is closed by the companion flange 14. Is open to the space X2 on the other axial end side. In this embodiment, the hole diameter of the vent hole 15 is constant.

  In the propeller shaft according to the present embodiment configured as described above, power is transmitted as the companion flange 14, the constant velocity universal joint 4, and the power transmission shaft 1 rotate integrally.

  At this time, the pressure of the gas in the joint internal space X may increase due to heat generation during rotation, but the joint internal space X and the internal space Y of the hollow shaft 3 are communicated with each other through the air vent 15. The gas in the joint internal space X can be released to the internal space Y of the hollow shaft 3 through the through hole. Since the internal space Y of the hollow shaft 3 has a sufficiently large volume compared to the joint internal space X, the volume increase due to the gas discharged through the vent hole 15 is absorbed by the internal space Y of the hollow shaft 3. Can do. Therefore, the air permeability of the joint internal space X can be sufficiently ensured, and excessive deformation of the boot 12 due to gas expansion in the joint internal space X can be reliably prevented.

  Further, since the vent hole 15 has a sufficiently long path length corresponding to the axial dimension of the stub shaft 2, it is possible to effectively suppress a situation where grease leaks through the vent hole 15. And both joint internal space X and the internal space of the hollow shaft 3 are sealed spaces, and since these sealed spaces are connected by the vent hole 15, they do not communicate directly with the outside air. Therefore, the space formed by the joint internal space X, the vent hole 15 and the internal space Y of the hollow shaft 3 is a closed space. Therefore, it is possible to reliably suppress a situation where foreign matter enters the joint internal space X from the outside.

  Furthermore, during rotation, the grease moves toward the outer diameter side of the joint internal space X by centrifugal force, so that it is difficult for the grease to leak from the air passage 15 provided at the rotation center of the stub shaft 2. Further, since the vent hole 15 is provided on the axial center of the stub shaft 2, the center of gravity of the stub shaft 2 is not decentered by the vent hole 15, so that the stub shaft 2 can be maintained in a stable rotational state. it can.

  In the first embodiment, the joint inner space X is sealed with the boot 12 and the companion flange 14. However, as shown in FIG. 2, the space X2 on the other end side in the axial direction of the outer ring 6 is formed. After closing with the seal plate 16, the companion flange 14 may be fixed to the other axial end of the outer ring 6, and the seal plate 16 may be accommodated inside the companion flange 14. That is, the joint internal space X may be sealed by the boot 12 and the seal plate 16 (sealing member).

  FIG. 3 is a longitudinal sectional view showing a propeller shaft according to the second embodiment of the present invention. The difference between the propeller shaft according to the second embodiment and the propeller shaft according to the first embodiment described above is that the end of the vent hole 15 opened to the joint internal space X is covered with the seal plate 21. It is in.

  Specifically, as shown in an enlarged view in FIG. 4, a seal plate having a recess 2 c formed at the tip of the stub shaft 2 and a vent hole 22 having an opening area smaller than that of the vent hole 15 in the recess 2 c. 21 is press-fitted and fixed. The vent hole 22 of the seal plate 21 is located on the rotation axis of the stub shaft 2, and the hole diameter (diameter) is set to 1 to 2 mm, for example.

  In this way, the opening area of the vent hole 15 of the stub shaft 2 with respect to the joint internal space X can be indirectly reduced by the seal plate 21, so that the seal plate 21 having the vent hole 22 has air permeability. It functions as a resistance imparting member that maintains and imparts outflow resistance to the grease. Therefore, leakage of grease from the joint internal space X can be more effectively suppressed.

  FIG. 5 is a longitudinal sectional view showing a propeller shaft according to the third embodiment of the present invention. The propeller shaft according to the third embodiment is different from the propeller shaft according to the first and second embodiments described above in that the end portion of the vent hole 15 opened to the joint internal space X is formed by the elastic member 31. It is in the point covered.

  More specifically, as shown in an enlarged view in FIG. 6, a concave portion 2c is formed at the tip of the stub shaft 2, and an elastic member 31 is compressed and inserted into the concave portion 2c toward the inner diameter side. The elastic member 31 is fixed to the recess 2c by a restoring force. In the present embodiment, by fitting the fitting recess 31a formed on the outer peripheral surface of the elastic member 31 and the fitting convex portion 2c1 formed on the inner peripheral surface of the recess 2c of the stub shaft 2, The fixing force of the elastic member 31 is improved. As shown in FIGS. 6 and 7, the elastic member 31 is provided with a linear slit 32 that can be opened and closed.

  In this way, only when the gas pressure in the joint internal space X is increased, the slit 32 of the elastic member 31 is opened by the expansion of the gas, so that the leakage of grease can be prevented more reliably. That is, in this case, the elastic member 31 having the slits 32 functions as a resistance applying member that maintains air permeability and provides outflow resistance to the grease.

  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, in the above embodiment, the case where one end of the vent hole 15 is opened to the space X2 on the other end side in the axial direction of the outer ring 6 closed by the companion flange 14 or the seal plate 16 has been described. One end of the vent hole 15 may be opened to the space X1 on one end side in the axial direction of the outer ring 6 closed by the boot 12.

  Specifically, the vent hole 15 is extended from the inner space Y of the hollow shaft 3 along the rotation axis of the stub shaft 2, and the vent hole 15 is bent to the outer diameter side in the middle to end one end in the axial direction of the outer ring 6. You may make it open to the space X1 of the part side. The bent portion of the vent hole 15 may be orthogonal to the axis of the stub shaft 2 or may be inclined with respect to the axis. In this way, even if grease enters the vent hole 15, the bent portion of the vent hole 15 extends from the center of rotation to the outer diameter side. Grease can be pushed back into space X1.

  Further, the constant velocity universal joint 4 is not limited to a sliding type constant velocity universal joint, and the present invention can be similarly applied to a fixed type constant velocity universal joint.

It is sectional drawing which shows typically the propeller shaft which concerns on 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows typically the propeller shaft which shows the modification of FIG. It is a longitudinal cross-sectional view which shows typically the propeller shaft which concerns on 2nd Embodiment of this invention. FIG. 4 is an enlarged view of a region A in FIG. 3. It is a longitudinal cross-sectional view which shows typically the propeller shaft which concerns on 3rd Embodiment of this invention. FIG. 6 is an enlarged view of a region B in FIG. 5. It is an arrow view of the C direction of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power transmission shaft 2 Stub shaft 3 Hollow shaft 4 Constant velocity universal joint 5 Inner ring 6 Outer ring 7 Ball 8 Cage 9 Snap ring 10 Boot adapter 11 Bolt 12 Boot 13 Boot band 14 Companion flange 15 Vent hole 21 Seal plate 31 Elastic member

Claims (6)

A constant velocity universal joint that transmits torque via a torque transmission member between the inner joint member and the outer joint member, a hollow shaft that transmits torque between the inner joint member, and one of the outer joint members In a propeller shaft comprising a boot that closes an opening, and a sealing member that closes the other opening of the outer joint member,
A propeller shaft, wherein a joint internal space sealed by the boot and the sealing member is communicated with an internal space of the hollow shaft through a ventilation path.   The propeller shaft according to claim 1, wherein the air passage is provided on a stub shaft having one end connected to the inner joint member and the other end connected to the hollow shaft outside the boot.   The propeller shaft according to claim 2, wherein the air passage is provided on an axis of the stub shaft.   The propeller shaft according to any one of claims 1 to 3, wherein a resistance imparting member capable of venting and imparting outflow resistance to the grease is disposed in an opening of the air passage in the joint internal space side.   The propeller shaft according to claim 4, wherein the resistance imparting member is formed of a seal plate having a through hole.   The propeller shaft according to claim 4, wherein the resistance applying member is formed of an elastic body having a slit.

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