JP6969269B2 - Vehicle power transmission shaft - Google Patents

Description

The present invention relates to a vehicle power transmission shaft whose rigidity changes due to twisting.

In a power transmission path from a power source for driving a vehicle to a drive wheel, a power transmission shaft for a vehicle as a rotation shaft provided for transmitting the power output from the power source to the drive wheels is known. For example, the power transmission shaft for a vehicle described in Patent Document 1 is that. The vehicle power transmission shaft described in Patent Document 1 includes a first shaft that transmits torque and a second shaft that rotates on the same rotation center line as the rotation center line of the first shaft. When a predetermined twist angle is reached due to an increase in the torque to be transmitted, the protrusion provided on the first shaft and the protrusion provided on the second shaft come into contact with each other in the circumferential direction, so that the power transmission shaft for a vehicle that transmits torque abuts. Rigidity changes.

Japanese Unexamined Patent Publication No. 2010-121738

In the vehicle power transmission shaft described in Patent Document 1, when the first shaft reaches a predetermined twist angle, the rigidity of the vehicle power transmission shaft changes from low rigidity to high rigidity, so that the transmission is performed in the vicinity of the region where the rigidity is switched. When the torque is changed, the rigidity changes abruptly and the behavior may become unstable.

The present invention has been made to solve such a problem, and to provide a power transmission shaft for a vehicle in which the rigidity is increased as the torque to be transmitted increases without a sudden change in the rigidity. be.

The gist of the present invention is that the first shaft that transmits a rotational force about the rotation center line and the movement in the direction of the rotation center line are restricted, and the rotation is between the first shaft. It comprises a second shaft that includes a spline-fitted fitting that allows relative rotation in a gap of a predetermined angle around the centerline, with constant velocity joints between the differential gearing device and the drive wheels, respectively. the power transmission shaft for a vehicle to be coupled Te, wherein one of the first shaft and the second shaft has a hollow portion, said fitting portion, one of said first shaft and said second shaft The inner peripheral surface of the hollow portion and the outer peripheral surface of the first shaft and the other outer peripheral surface of the second shaft are spline-fitted, and the gap disappears as the twist of the first shaft increases. The fitting region is to increase in the direction of the rotation center line.

According to the vehicle power transmission shaft of the present invention , which is connected between the differential gear device and the drive wheel via constant velocity joints, one of the first shaft and the second shaft has a hollow portion. The fitting portion is such that the inner peripheral surface of one of the first shaft and the second shaft and the other outer peripheral surface of the first shaft and the second shaft are spline-fitted. As the twist of the first shaft increases, the fitting region where the gap disappears increases in the direction of the rotation center line. Therefore, since the fitting region increases as the transmitted torque increases, the rigidity does not change abruptly, and the vehicle power transmission shaft can increase the rigidity by increasing the transmitted torque.

It is a perspective view of the driving force transmission device which mounts the power transmission shaft for a vehicle which is one Embodiment of this invention. It is a figure which shows the outline of a part of the driving force transmission device of FIG. It is a figure which shows the outline of the connection part with the 1st constant velocity joint of the power transmission shaft for a vehicle of FIG. It is a figure which shows the outline of the power transmission shaft for a vehicle of FIG. It is a VV sectional view of the power transmission shaft for a vehicle of FIG. It is a VI-VI sectional view of the power transmission shaft for a vehicle of FIG. 2 is a diagram showing the twist characteristics of the vehicle power transmission shaft of FIG. 2, wherein the transmission torque T of the vehicle power transmission shaft and the twist angle θT of the other end with respect to one end in one end region of the axle. It is a figure which shows the relationship. FIG. 7 is a diagram showing a range of a fitted region and a non-fitted region of a vehicle power transmission shaft in the non-fitted state of FIG. 7. It is a figure which shows the range of the fitted region and the non-fitted region of the power transmission shaft for a vehicle in the partially fitted state of FIG. 7. It is a figure which shows the range of the fitted region and the non-fitted region of the power transmission shaft for a vehicle in the fully fitted state of FIG. 7. It is a figure which shows the outline of the power transmission shaft for a vehicle which is another embodiment of this invention. FIG. 11 is a side view showing the axle and the outer shaft of FIG. 11 with a part cut out in a plane including a rotation center line. FIG. 12 is a sectional view taken along line XIII-XIII of the power transmission shaft for a vehicle shown in FIG. FIG. 12 is a sectional view taken along line XIV-XIV of the power transmission shaft for a vehicle shown in FIG.

In one embodiment of the present invention, the first shaft has the hollow portion, and the second shaft is restricted from moving toward the rotation center line in the end region of the first shaft.

In one embodiment of the present invention, the second shaft has the hollow portion, and the second shaft is a snap ring provided on the outer peripheral surface of the first shaft so as to sandwich both ends of the second shaft. This restricts the movement in the direction of the rotation center line.

Hereinafter, examples of the power transmission shaft for a vehicle of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a power transmission device 120 equipped with a vehicle power transmission shaft 100, which is an embodiment of the present invention. Two constant velocity joints are provided between the differential gear device 12 and the pair of drive wheels (not shown), and the first constant velocity joint 14 is arranged on the differential gear device 12 side, and the drive wheel side. A second constant velocity joint 20 is arranged in the. A vehicle power transmission shaft 100 including an axle 16 is provided between the first constant velocity joint 14 and the second constant velocity joint 20, respectively.

FIG. 2 is a diagram showing an outline of a part of the power transmission device 120 of FIG. FIG. 2 shows a portion of the first constant velocity joint 14, the vehicle power transmission shaft 100, and the second constant velocity joint 20 cut out in a plane including the respective rotation center lines C1, C2, and C3. It is a side view. The first constant velocity joint 14 is connected so as to be relatively non-rotatable around the rotation center line C1 of the connecting shaft 22 to which power is transmitted from the differential gear device 12 and to be relatively rotatable in a plane including the rotation center line C1. The shaft 22 and the axle 16 are connected, and the torque (rotational force) output from the connecting shaft 22 is transmitted to the axle 16 side at an equiangular speed. Further, the second constant velocity joint 20 connects the axle 16 and the connecting shaft 52 so that the axle 16 cannot rotate relative to the rotation center line C2 and can rotate relative to the plane including the rotation center line C2. The torque (rotational force) output from the axle 16 is transmitted to the connecting shaft 52 side at an equal angular velocity.

The axle 16 has a cylindrical shape and has a hollow portion 16o inside. The axle 16 has a central region 16l, one end region 16m on the first joint 14 side from the central region 16l and a smaller outer diameter than the central region 16l, and a central region 16l to the second joint 20. It has the other end region 16n, which is on the side and has an outer diameter smaller than that of the central region 16l. The outer diameter of the axle 16 gradually decreases from the central region 16l to one end region 16m, and the outer diameter thereof gradually decreases from the central region 16l to the other end region 16n. It has become. The central region 16l, one end region 16m, and the other end region 16n are rotatable along the same rotation center line C2, and the hollow portion 16o communicates these three regions. The one end region 16m and the other end region 16n of the axle 16 have lower torsional rigidity (rigidity against torsion) than the central region 16l.

FIG. 3 is a diagram showing an outline of a connecting portion of the vehicle power transmission shaft 100 of FIG. 2 with a first constant velocity joint 14. FIG. 3 is a side view showing the first constant velocity joint 14 and the vehicle power transmission shaft 100 with a part cut out in a plane including the respective rotation center lines C1 and C2.

The joint portion 24 of the first constant velocity joint 14 is connected to the outer race 26 integrally having a connecting shaft 22 to which power is transmitted from the differential gear device 12 by spline fitting to the axle 16 and is connected to the outer race 26. An inner race 28 to be accommodated, a plurality of balls 30 which are torque transmission members interposed between the outer race 26 and the inner race 28, and a cage 32 for rotatably holding the plurality of balls 30. It is equipped with boots 50.

The outer race 26 is rotatably formed around the rotation center line C1 of the connecting shaft 22 and extends in the direction of the rotation center line C1 of the connecting shaft 22 and the opening 34 provided at one end opposite to the connecting shaft 22. It is provided with a ball rolling groove 40 formed in a groove shape.

The inner race 28 functions as a connecting portion between the spherical outer peripheral surface 42, the ball rolling groove 44 formed in a groove shape on the outer peripheral surface 42 so as to extend in the direction of the rotation center line C2 of the axle 16, and the axle 16. The inner peripheral spline teeth 28a and the like are provided. By connecting the inner peripheral spline teeth 28a of the inner race 28 and the spline teeth 16w at one end of the axle 16 by spline fitting, the inner race 28 rotates integrally around the rotation center line C2 common to the axle 16. It is configured to be made to.

The plurality of balls 30 are rotatably fitted in the space between the ball rolling groove 40 formed in the outer race 26 and the ball rolling groove 44 formed in the inner race 28.

The cage 32 includes a spherical outer peripheral surface 46 that partially slides on the inner wall surface of the outer race 26, and a spherical inner peripheral surface 48 that partially slides on the outer peripheral surface 42 of the inner race 28. , Prevents the plurality of balls 30 from falling out of the ball rolling groove 40 and the ball rolling groove 44.

The boot 50 is made of an elastic material such as rubber and is formed in a cylindrical shape, and has a function of sealing the inside of the joint portion 24 against earth and sand, water and the like from the outside.

With the above configuration, the first constant velocity joint 14 allows an angular displacement between the axle 16 and the connecting shaft 22 (change in the angle formed by the rotation center line C2 of the axle 16 and the rotation center line C1 of the connecting shaft 22). At the same time, torque is transmitted between the outer race 26 and the inner race 28 via the plurality of balls 30.

The vehicle power transmission shaft 100 includes an axle 16 and an inner shaft 60. The axle 16 corresponds to the first shaft of the present invention, and the inner shaft 60 corresponds to the second shaft of the present invention. One end region 16m of the axle 16 is a spline portion 16a having spline teeth 16u extending in parallel with the rotation center line C2 on the inner peripheral surface 16p of the hollow portion 16o, and a fixing for fixing the inner shaft 60 described later. It comprises a fixing portion 16b having teeth 16v.

FIG. 4 is a diagram showing an outline of the power transmission shaft 100 for a vehicle, and is a side view showing the axle 16 and the inner shaft 60 with a part cut out in a plane including the rotation center line C2. The inner shaft 60 has a substantially cylindrical shape, and has a spline portion 60a having spline teeth 60u extending in parallel with the rotation center line C2 on the outer peripheral surface 60p on one end 60s side, and a hollow axle 16 on the other end 60t side. It includes a stopper 60c having an outer diameter larger than the inner diameter of the portion 16o, and a fixing portion 60b having a fixing tooth 60v provided so as to mesh with the fixing tooth 16v of the axle 16 between the spline portion 60a and the stopper 60c. .. In the direction of the rotation center line C2, the spline portion 16a and the spline portion 60a are longer than the fixed portion 16b and the fixed portion 60b, respectively. The inner shaft 60 is chamfered at the tip end portion on the one end portion 60s side.

FIG. 5 is a sectional view taken along line VV of the power transmission shaft 100 for a vehicle of FIG. A plurality of spline teeth 16u of the axle 16 and spline teeth 60u of the inner shaft 60 are provided at equal intervals in the circumferential direction of the rotation center line C2 (8 in this embodiment), and these are spline-fitted. .. At this time, the spline tooth 16u of the axle 16 has an angle ψ (rad) in the circumferential direction of the rotation center line C2 with the spline tooth 60u of the inner shaft 60 in the rotation direction (direction in which the spline tooth 16u advances due to rotation). The gap G is provided. Therefore, when the axle 16 is twisted by an angle ψ (rad) in the circumferential direction of the rotation center line C2, the spline teeth 16u of the axle 16 and the spline teeth 60u of the inner shaft 60 come into contact with each other and rotate. The angle ψ corresponds to a predetermined angle of the present invention.

FIG. 6 is a VI-VI cross-sectional view of the power transmission shaft 100 for a vehicle of FIG. At the tip of the axle 16, a plurality of fixed teeth 16v of the axle 16 and 60v of the fixing teeth of the inner shaft 60 are provided at equal intervals in the circumferential direction of the rotation center line C2 (8 in this embodiment). The inner shaft 60 is fixed to the axle 16 by the fitting of. Since the inner shaft 60 is fixed at the tip of the axle 16 in this way, the influence on the characteristics of the torsional rigidity of the axle 16 is small. The term "fixed" here means that the fixed teeth 16v of the axle 16 and the fixed teeth 60v of the inner shaft 60 are in contact with each other regardless of the twist of the axle 16, and the axle 16 and the inner shaft 60 are in contact with each other on the rotation center line C2. It means that it is fixed so that it can rotate without relative rotation. Further, the fitting of the fixed teeth 16v of the axle 16 and the fixed teeth 60v of the inner shaft 60 and the stopper 60c restrict the movement of the inner shaft 60 in the rotation center line C2 direction.

FIG. 7 is a diagram showing the twist characteristics of the vehicle power transmission shaft 100 of FIG. 2, wherein the transmission torque T of the vehicle power transmission shaft 100 and the other end of the axle 16 in one end region 16 m are shown. It is a figure which shows the relationship with the twist angle θT of an end part. 8 to 10 are diagrams showing the ranges of the fitted region 90a and the non-fitted region 90b of the vehicle power transmission shaft 100 in the non-fitted state, the partially fitted state, and the fully fitted state in FIG. 7, respectively. The fitting region 90a refers to a region in which the gap G between the spline teeth 16u and the spline teeth 60u disappears due to the twist of the axle 16, that is, the spline teeth 16u and the spline teeth 60u are in contact with each other and rotate. In the non-fitting region 90b, even if the axle 16 is twisted, a gap G exists between the spline teeth 16u and the spline teeth 60u, and the spline teeth 16u and the spline teeth 60u rotate without contacting each other. Refers to an area.

As shown in FIG. 7, in the vehicle power transmission shaft 100, the transmission torque T is lower than, for example, a set predetermined torque T1, and the torque is transmitted only through the axle 16 in a non-fitting state. In this case, as shown in FIG. 8, the spline teeth 16u and the spline teeth 60u are all non-fitting regions 90b in which a gap G exists, and the torsional rigidity of the vehicle power transmission shaft 100 is low. There is.

As shown in FIG. 7, when the transmission torque T is between the predetermined torque T1 and the predetermined torque T2 (the predetermined T2 is larger than the predetermined torque T1), the axle 16 is twisted on the other end 60t side of the inner shaft 60. This results in a partially fitted state in which a fitting region 90a in which the gap G between the spline teeth 16u and the spline teeth 60u disappears appears. In this case, as shown in FIG. 9, the fitting region 90a exists on the other end 60t side of the inner shaft 60, and the non-fitting region 90b exists on the one end 60s side of the inner shaft 60. When the transmission torque T becomes large, the fitting region 90a increases and the non-fitting region 90b decreases as shown by the white arrow in FIG. On the contrary, when the transmission torque T becomes small, the fitting region 90a decreases and the non-fitting region 90b increases as shown by the black arrow in FIG. Since the fitting region 90a rotates while the axle 16 and the inner shaft 60 are in contact with each other, the torsional rigidity is higher than when the axle 16 is rotated without being in contact with the inner shaft 60. Therefore, in the partially fitted state, the fitting region 90a in which the torsional rigidity is high and the non-fitting region 90b in which the torsional rigidity is not changed are mixed, and the fitting region is increased according to the increase in the transmission torque T. Since 90a continuously increases, as the transmission torque T increases, the torsional rigidity also continuously increases.

As shown in FIG. 7, when the transmission torque T exceeds the predetermined torque T2, the increase in the fitting region 90a in which the gap G between the spline teeth 16u and the spline teeth 60u disappears due to the twist of the axle 16 is saturated, and the inner shaft becomes saturated. It is in a fully fitted state extending to the vicinity of the fixed portion 60b of the 60. In this case, as shown in FIG. 10, the fitting region 90a in which the gap G does not exist occupies between the spline teeth 16u and the spline teeth 60u, and the torsional rigidity of the vehicle power transmission shaft 100 is high. Strictly speaking, since the twist angle with respect to the length of the axle 16 in the rotation center line C2 direction is a finite value, it is possible that only the gap G is twisted at the boundary portion of the spline portion 16a of the axle 16 with the fixed portion 16b. Since there is no such portion, a partially non-fitting region 90b exists in the vicinity of the fixed portion 16b. The angles ψ of the predetermined torques T1 and T2 and the gap G are values obtained in advance from experiments and the like so as to have a desired torsional rigidity.

Although detailed description will be omitted, the torsional rigidity of the other end region 16n of the axle 16 is also changed by the same structure as that of the above embodiment in the one end region 16m.

According to the vehicle power transmission shaft 100 of the present embodiment, the axle 16 has a hollow portion 16o, and is provided on the spline teeth 16u provided on the inner peripheral surface 16p of the hollow portion 16o and the outer peripheral surface 60p of the inner shaft 60. The spline teeth 60u and the spline teeth 60u are spline-fitted with a gap G in the circumferential direction around the rotation center line C2, and the fitting region 90a where the gap G disappears as the twist of the axle 16 increases is the rotation center. It increases in the direction of line C2. Therefore, as the transmitted torque increases, the fitting region 90a in which the torsional rigidity increases continuously increases, so that the torsional rigidity does not change abruptly, and the vehicle power transmission shaft 100 has the transmitted torque. Since the torsional rigidity increases due to the increase in the torque, the durability is improved and the operation stability of the vehicle is ensured.

Further, according to the vehicle power transmission shaft 100 of the present embodiment, the inner shaft 60 is fixed at the tip of the axle 16 which has little influence on the torsional rigidity of the axle 16. Therefore, in applying the present invention, the influence on the torsional rigidity of the vehicle power transmission shaft 100 is small.

FIG. 11 is a diagram showing an outline of a power transmission shaft 110 for a vehicle, which is another embodiment of the present invention. FIG. 11 shows the first constant velocity joint 14, the vehicle power transmission shaft 110, and the second constant velocity joint 20 with a portion cut out in a plane including the respective rotation center lines C1, C2, and C3. It is a side view. In the following description, the same reference numerals are given to the parts common to the above-described first embodiment, and the description thereof will be omitted as appropriate.

The connecting structure of the connecting shaft 22 and the axle 18 in the first constant velocity joint 14 of the present embodiment is the same as the connecting structure of the connecting shaft 22 of the first constant velocity joint 14 and the axle 16 in the first embodiment. Further, the connecting structure of the connecting shaft 52 and the axle 18 in the second constant velocity joint 20 of this embodiment is the same as the connecting structure of the connecting shaft 52 of the second constant velocity joint 20 and the axle 16 in the first embodiment. .. Unlike the first embodiment, the vehicle power transmission shaft 110 of this embodiment does not have an inner shaft 60, but instead includes an outer shaft 70 that covers the outer periphery of the axle 18. The vehicle power transmission shaft 110 includes an axle 18 and an outer shaft 70. The axle 18 corresponds to the first shaft of the present invention, and the outer shaft 70 corresponds to the second shaft of the present invention.

The axle 18 has a cylindrical shape, and has a central region 18l, one end region 18m on the first joint 14 side of the central region 18l and a smaller outer diameter than the central region 18l, and a central portion. The other end region 18n, which is on the second joint 20 side of the region 18l and has a smaller outer diameter than the central region 18l, is provided. The outer diameter of the axle 18 gradually decreases from the central region 18l to one end region 18m, and the outer diameter thereof gradually decreases from the central region 18l to the other end region 18n. It has become. The central region 18l, one end region 18m, and the other end region 18n are made rotatable along the same rotation center line C2. The central region 18l of the axle 18 has higher torsional rigidity than the one end region 18m and the other end region 18n.

The outer shaft 70 is a cylindrical tube having a hollow portion 70o having an inner diameter larger than the outer diameter of the axle 18. The axle 18 is inserted through the hollow portion 70o of the outer shaft 70, and as will be described later, the outer peripheral surface 18p of the central region 18l of the axle 18 and the inner peripheral surface 70p of the hollow portion 70o of the outer shaft 70 face each other. ..

FIG. 12 is a side view showing the axle 18 and the outer shaft 70 of FIG. 11 with a part cut out in a plane including the rotation center line C2.

The outer shaft 70 includes a spline portion 70a provided on the one end 70s side and a fixing portion 70b provided on the other end 70t side. The spline portion 70a has spline teeth 70u extending in parallel with the rotation center line C2 on the inner peripheral surface 70p of the hollow portion 70o. The fixing portion 70b has fixing teeth 70v for fixing the outer shaft 70 to the axle 18 on the inner peripheral surface 70p of the hollow portion 70o.

The axle 18 includes a spline portion 18a having spline teeth 18u facing the spline teeth 70u of the outer shaft 70, and a fixing portion 18b having fixed teeth 18v provided so as to mesh with the fixed teeth 70v of the outer shaft 70. .. In the direction of the rotation center line C2, the spline portion 18a and the spline portion 70a are longer than the fixed portion 18b and the fixed portion 60b, respectively. The outer shaft 70 is chamfered on the outer peripheral surface side and the inner peripheral surface 70p side at the tip portions of one end portion 70s and the other end portion 70t. Further, there are two grooves formed in the circumferential direction on the outer peripheral portion of the axle 18, and the snap ring 80 fitted in one groove faces one end 70s of the outer shaft 70, and the other groove is formed. The snap ring 82 fitted in the outer shaft 70 faces the other end 70t of the outer shaft 70.

FIG. 13 is a sectional view taken along line XIII-XIII of the power transmission shaft 110 for a vehicle of FIG. A plurality of spline teeth 18u of the axle 18 and spline teeth 70u of the outer shaft 70 are provided at equal intervals in the circumferential direction of the rotation center line C2 (8 in this embodiment), and these are spline-fitted. .. At this time, the spline tooth 18u of the axle 18 has an angle ψ (rad) in the circumferential direction of the rotation center line C2 between the spline tooth 18u of the outer shaft 70 and the spline tooth 70u of the outer shaft 70 in the rotation direction (direction in which the spline tooth 18u advances due to rotation). ) Is provided with a gap G1. Therefore, when the axle 18 is twisted by an angle ψ (rad) in the circumferential direction of the rotation center line C2, the spline teeth 18u of the axle 18 and the spline teeth 70u of the outer shaft 70 come into contact with each other and rotate. The angle ψ corresponds to a predetermined angle of the present invention.

FIG. 14 is a sectional view taken along line XIV-XIV of the power transmission shaft 110 for a vehicle of FIG. A plurality of fixed teeth 18v of the axle 18 and 70v of the fixing teeth of the outer shaft 70 are provided at equal intervals in the circumferential direction of the rotation center line C2 (8 in this embodiment), and the outer shaft is fitted by fitting them. 70 is fixed to the axle 18. This fixing means that the fixed teeth 18v of the axle 18 and the fixed teeth 70v of the outer shaft 70 are in contact with each other regardless of the twist of the axle 18, and the axle 18 and the outer shaft 70 cannot rotate relative to each other at the rotation center line C2. It means that it is fixed to rotate with. Further, the fitting of the fixed teeth 18v of the axle 18 and the fixed teeth 70v of the outer shaft 70 and the snap rings 80 and 82 restrict the movement of the outer shaft 70 in the rotation center line C2 direction.

Also in this embodiment, the relationship between the twist characteristics of the vehicle power transmission shaft 110 and the transmission torque T of the vehicle power transmission shaft 110 and the twist angle θT of the other end with respect to one end in the central region 18l of the axle 18. Is the same as in FIG. 7 in the above-mentioned Example 1. In this embodiment, the region where the gap G1 between the spline teeth 18u and the spline teeth 70u disappears due to the twist of the axle 18, that is, the region where the spline teeth 18u and the spline teeth 70u abut and rotate is defined as the fitting region 92a. Even if the axle 18 is twisted, a gap G1 exists between the spline teeth 18u and the spline teeth 70u, and the region where the spline teeth 18u and the spline teeth 70u rotate without contacting each other is referred to as a non-fitting region 92b. Then, the ranges of the fitting region 92a and the non-fitting region 92b of the vehicle power transmission shaft 110 are as follows.

In a non-fitting state where the transmission torque T is less than, for example, a set predetermined torque T1 and the torque is transmitted only through the axle 16, the vehicle power transmission shaft 110 is between the spline teeth 18u and the spline teeth 70u. Are all non-fitting regions 92b in which the gap G1 exists.

In the partially fitted state in which the transmission torque T is between the predetermined torque T1 and the predetermined torque T2 (the predetermined T2 is larger than the predetermined torque T1), the vehicle power transmission shaft 110 is the one end 70s of the outer shaft 70. The fitting region 92a exists on the side, and the non-fitting region 92b exists on the other end 70t side of the outer shaft 70. When the transmission torque T becomes large, the fitting region 92a increases in the rotation center line C2 direction, and the non-fitting region 92b decreases. On the contrary, when the transmission torque T becomes small, the fitting region 92a decreases in the rotation center line C2 direction, and the non-fitting region 92b increases. Therefore, in the partially fitted state, the fitting region 92a in which the torsional rigidity is high and the non-fitting region 92b in which the torsional rigidity is not changed are mixed, and the fitting region is increased according to the increase in the transmission torque T. Since 92a continuously increases, as the transmission torque T increases, the torsional rigidity also continuously increases.

In the fully fitted state where the transmission torque T exceeds the predetermined torque T2, the increase in the fitting region 92a in which the gap G1 between the spline teeth 18u and the spline teeth 70u disappears due to the twist of the axle 18 is saturated, and the outer shaft 70 is fixed. It extends to the vicinity of part 70b. Strictly speaking, since the twist angle of the axle 18 with respect to the length in the rotation center line C2 direction is a finite value, it is possible that only the gap G1 is twisted at the boundary portion of the spline portion 18a of the axle 18 with the fixed portion 18b. Since there is no such portion, a partially non-fitting region 92b exists in the vicinity of the fixed portion 18b.

According to the vehicle power transmission shaft 110 of the present embodiment, the outer shaft 70 has a hollow portion 70o, and is provided on the spline teeth 70u provided on the inner peripheral surface 70p of the hollow portion 70o and on the outer peripheral surface 18p of the axle 18. The spline teeth 18u are spline-fitted with a gap G1 in the circumferential direction around the rotation center line C2, and the fitting region 92a at which the gap G1 disappears as the twist of the axle 18 increases is the rotation center. It increases in the line C2 direction. Therefore, as the transmitted torque increases, the fitting region 92a in which the torsional rigidity increases continuously increases, so that the torsional rigidity does not change abruptly, and the vehicle power transmission shaft 110 transmits the torque. Since the torsional rigidity increases due to the increase in the torque, the durability is improved and the operation stability of the vehicle is ensured.

Further, according to the vehicle power transmission shaft 110 of the present embodiment, the axle 18 is not one end region 18m or the other end region 18n, which has a relatively low torsional rigidity, but has a large outer diameter and a large torsional rigidity. In the central region 18l, which is relatively high, the torsional rigidity is increased. Therefore, in applying the present invention, there is little concern that the strength of the vehicle power transmission shaft 110 will decrease.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is also applicable to other aspects.

In Example 1 described above, the present invention has been applied, but is not limited to, in both the one end region 16m and the other end region 16n of the axle 16. The present invention may be applied in at least one region of one end region 16m and the other end region 16n.

In Examples 1 and 2 described above, the inner shaft 60 is fixed to the axle 16 and the outer shaft 70 is fixed to the axle 18 with the fixed teeth 60v meshed tightly in the circumferential direction of the rotation center line C2, respectively. This was done by fitting the teeth 16v or fitting the fixed teeth 70v and the fixed teeth 18v, but the present invention is not limited to this. For example, other methods such as tightening by press fitting and welding may be used.

In the second embodiment described above, the outer shaft 70 is fixed to the axle 18 by fitting the fixed teeth 70v and the fixed teeth 18v that are meshed tightly in the circumferential direction of the rotation center line C2, but the circumference of the rotation center line C2. It does not have to be fixed without a gap in the direction. For example, the outer shaft 70 may have no fixed portion 70b, the axle 18 may also have no fixed portion 18b, and the spline portion 70a may be used for everything from one end 70s to the other 70t. Specifically, as shown in FIG. 13, the spline tooth 18u of the axle 18 has a rotation center line between the spline tooth 18u of the outer shaft 70 and the spline tooth 70u of the outer shaft 70 in the rotation direction (direction in which the spline tooth 18u advances due to rotation). A gap G1 having an angle ψ (rad) is provided in the circumferential direction of C2, and is angled in the circumferential direction of the rotation center line C2 between the outer shaft 70 and the spline teeth 70u in the direction opposite to the rotation direction. A φ (rad) gap G2 may be provided. The angles ψ and φ correspond to the predetermined angles of the present invention. In this case, the axle 18 inserted through the hollow portion 70o of the outer shaft 70 is twisted by an angle ψ + φ (rad), so that the gap G1 or G2 between the spline teeth 70u of the spline portion 70a and the spline teeth 18u of the spline portion 18a The spline teeth 18u of the axle 18 and the spline teeth 70u of the outer shaft 70 come into contact with each other and rotate. Therefore, the fitting region 92a whose torsional rigidity is increased by eliminating the gap G1 according to the increase in the transmitted torque is on the other end 70t side (first constant velocity for transmitting power to the axle 18) in the direction of the rotation center line C2. The fitting region 92a, which continuously increases from the joint 14 side toward the central portion of the outer shaft 70 and has high torsional rigidity due to the elimination of the gap G2, is on the one end 70s side (axle 18) in the rotation center line C2 direction. Continuously increases from the second constant velocity joint 20 side) to which power is transmitted toward the central portion of the outer shaft 70. Therefore, even in this case, the torsional rigidity does not change abruptly due to the increase in the transmitted torque, and the torsional rigidity of the vehicle power transmission shaft 110 increases due to the increase in the transmitted torque, so that the durability is improved. And the operational stability of the vehicle is ensured. Further, by eliminating the fixed portion 70b of the outer shaft 70 and the fixed portion 18b of the axle 18, it is not necessary to form the fixed teeth 70v and the fixed teeth 18v that mesh with each other without gaps. , It becomes easy to manufacture.

In the second embodiment described above, the snap rings 80 and 82 are provided to restrict the movement of the outer shaft 70 in the rotation center line C2 direction, but the present invention is not limited to this. For example, even if the movement of the outer shaft 70 in the rotation center line C2 direction is restricted by attaching a fastener such as a clamp to the axle 18 so as to face one end 70s and the other end 70t of the outer shaft 70. good.

In the first embodiment described above, the stopper 60c restricts the movement of the inner shaft 60 in the direction of the rotation center line C2, and in the second embodiment described above, the snap rings 80 and 82 regulate the movement of the outer shaft 70 in the direction of the rotation center line C2. Movement to is restricted, but this configuration is not mandatory. For example, the inner shaft can be fixed by fitting the fixing portion 60b of the inner shaft 60 and the fixing portion 16b of the axle 16, or by fitting the fixing portion 70b of the outer shaft 70 and the fixing portion 18b of the axle 18. If the movement of the 60 and the outer shaft 70 in the rotation center line C2 direction is sufficiently restricted, the stopper 60c and the snap rings 80 and 82 may not be provided.

The gap G of the first embodiment and the gap G1 of the second embodiment are set to ψ (rad), and eight spline teeth 16u and spline teeth 60u, and eight spline teeth 18u and spline teeth 70u are arranged in the circumferential direction. However, it is not limited to this. Transmission is performed by appropriately changing the gap G of Example 1, the set values of the gaps G1 and G2 of Example 2, the number arranged in the circumferential direction of the rotation center line C2 of the spline teeth, and the shape of the teeth of the spline teeth. It is possible to adjust the torque value in which the non-fitted state, the partially fitted state, and the fully fitted state are obtained with respect to the torque, that is, the characteristics related to the twist of the transmission shaft for the vehicle.

It should be noted that the above is only one embodiment, and the present invention can be carried out in a mode in which various changes and improvements are made based on the knowledge of those skilled in the art.

16: Axle (first shaft)
16a: Spline portion 16b: Fixed portion 16o: Hollow portion 16p: Inner peripheral surface 60: Inner shaft (second shaft)
60a: Spline part (fitting part)
60b: Fixed portion 60p: Outer peripheral surface 100: Vehicle power transmission shaft G: Gap C2: Rotation center line

Claims (1)

The movement in the direction of the rotation center line is restricted between the first shaft that transmits the rotational force about the rotation center line, and the gap between the first shaft and the first shaft at a predetermined angle around the rotation center line. A vehicle power transmission shaft comprising a second shaft that includes a spline-fitted mating portion that allows relative rotation and is coupled between the differential gear device and the drive wheels via constant velocity joints, respectively. And
One of the first shaft and the second shaft has a hollow portion.
In the fitting portion, the inner peripheral surface of the hollow portion of one of the first shaft and the second shaft and the outer peripheral surface of the first shaft and the other outer peripheral surface of the second shaft are spline-fitted. Ori,
A vehicle power transmission shaft, characterized in that, as the twist of the first shaft increases, the fitting region where the gap disappears increases in the direction of the rotation center line.

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