JP4766236B2 - Vehicle drive shaft and manufacturing method thereof - Google Patents

Description

  The present invention relates to a drive shaft that transmits drive torque from a drive unit (engine) of an automobile and a method for manufacturing the drive shaft. More specifically, the present invention has a high vibration damping effect when used as a rotating shaft that rotates at high speed. The present invention relates to a drive shaft and a manufacturing method thereof.

Generally, in a power transmission device used in an automobile, driving torque from an engine is transmitted to a drive shaft through a transmission, a final reduction mechanism, a differential mechanism, and the like, and further transmitted to a driving wheel by the drive shaft. Is done. An example of a conventional drive shaft will be described with reference to FIGS. As shown in FIG. 6, the drive shaft 1 has constant velocity joints 3 and 4 (universal joints) attached to both ends of the shaft 2, and a differential mechanism is provided via these constant velocity joints 3 and 4. And coupled to the drive wheel. Then, the constant velocity joint 3 and 4, both when transmitting a driving torque, which absorbs movement of the wheel by suspension devices or steering system. The joint between the shaft 2 and the constant velocity joints 3 and 4 is covered with the boots 5 and 6, thereby holding the lubricant inside the constant velocity joints 5 and 6 and preventing foreign matter from entering from the outside. It is preventing.

  The drive shaft 1 is a rotating shaft that transmits a driving torque from the differential mechanism to the driving wheel. A large torque acts on the drive shaft 1 and vibration caused by meshing of the gears in the transmission, the final reduction mechanism, and the differential mechanism. The component is transmitted. This vibration component is amplified in the vicinity of the inherent bending resonance frequency of the shaft 2 and transmitted to the vehicle body via the suspension device or the like, causing unpleasant vibration and noise to the occupant.

Therefore, in order to suppress vibration transmitted to the shaft 2 from a differential mechanism or the like, conventionally, by increasing the diameter of the shaft 2 and making the interior hollow, the bending resonance frequency of the shaft 2 is increased, Resonance was prevented by moving away from the frequency of the vibration component. Further, as shown in FIG. 7, a dynamic damper 7 is attached to the shaft 2 to separate the peak of the bending resonance frequency and reduce the resonance magnification, or the solid shaft has two cross sections (non-circular). As a shape (see FIG. 8), the bending resonance frequency is given directionality to suppress vibration amplification (for example, see Patent Document 1).
JP 7-174132 A

  However, the above conventional measures have the following problems. If the diameter of the shaft 2 is changed or a large-diameter hollow shaft is used, the adjustment range is limited due to the problem of strength and weight increase, so it is difficult to obtain a sufficient damping effect. is there. In the case where the dynamic damper 7 is used, it is difficult to secure a mounting space for the dynamic damper 7 due to space limitations around the mounting portion of the drive shaft 1 to the vehicle, and in addition, the number of parts increases. Increase in weight and cost is inevitable. Moreover, in the thing described in patent document 1, in order to improve the damping effect, since it is necessary to take the aspect ratio of a cross-sectional shape sufficiently large, when it is going to ensure required intensity | strength, the longer dimension L is set. It becomes very big. For this reason, in addition to the problem of an increase in weight, it becomes difficult to insert the coil into the coil during induction hardening, and there arises a problem that the mountability of the boots 4 and 5 is deteriorated. Furthermore, in order to make the cross-sectional shape of the solid shaft 2 non-circular, machining such as cutting is necessary, and the manufacturing cost increases due to an increase in the number of processes.

  The present invention has been made in view of the above points, and provides a drive shaft for a vehicle and a method for manufacturing the same that can enhance the vibration damping effect while minimizing an increase in mounting space and weight. With the goal.

In order to solve the above-described problems, the invention according to claim 1 is directed to a vehicle drive shaft in which constant velocity joints are connected to both ends of an intermediate shaft and are respectively connected to a differential device side shaft and a wheel side shaft. ,
The intermediate shaft is formed of a pipe material having a hollow portion having an elliptical cross section perpendicular to the rotation axis, and the hollow portion is a shaft in the entire interior other than both ends to which the constant velocity joint of the intermediate shaft is connected. extends in the direction, Ri elliptical der any cross-section substantially the same shape and substantially the same size perpendicular to the axis of rotation,
The both end portions have a circular cross section perpendicular to the rotation axis, and have a diameter smaller than the diameter of the portion where the hollow portion is formed,
The intermediate shaft is formed by drawing and quenching a pipe material having a circular cross section at both ends, and the hollow portion is cold processed by pressing the pipe material having a circular cross section from the outside in the diameter direction. Is formed into an elliptical shape .
The invention according to claim 2 is a method for manufacturing a vehicle drive shaft, in which constant velocity joints are connected to both ends of the intermediate shaft, and are connected to the differential device side shaft and the wheel side shaft, respectively.
The intermediate shaft is formed of a pipe material having a hollow portion having an elliptical cross section perpendicular to the rotation axis, and the hollow portion is a shaft in the entire interior other than both ends to which the constant velocity joint of the intermediate shaft is connected. Arbitrary cross sections extending in the direction and orthogonal to the rotation axis are substantially the same shape and substantially the same size elliptical shape,
The both end portions have a circular cross section perpendicular to the rotation axis, and have a diameter smaller than the diameter of the portion where the hollow portion is formed,
The intermediate shaft is formed by shrinking both ends of a pipe member having a circular cross section by drawing, quenching to form the both ends, and pressing the intermediate portion from the outside in the diametrical direction to cold work. The method includes a step of forming the hollow portion by forming an elliptical shape.

  According to the vehicle drive shaft of the present invention, it is possible to increase the vibration damping effect and reduce the generation of vibration and noise while minimizing the increase in mounting space and weight. In addition, according to the vehicle drive shaft manufacturing method of the present invention, a vehicle drive shaft having a hollow portion having an elliptical cross-section perpendicular to the rotation axis can be easily manufactured.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, a drive shaft 8 (vehicle drive shaft) according to the present embodiment includes a transmission driven by an engine, a final reduction mechanism, and a differential mechanism (differential) in a power transmission device for a front-wheel drive automobile. A rotating shaft for transmitting a driving force to a driving wheel from a transaxle (transmission device) in which a device is integrated. In the drive shaft 8, constant velocity joints 10 and 11 are connected to both ends of a hollow intermediate shaft 9, and a joint portion between the intermediate shaft 9 and the constant velocity joints 10 and 11 is covered with boots 12 and 13. Yes.

  One constant velocity joint 10 is a sliding type constant velocity joint that can be expanded and contracted in the axial direction to be connected to a transaxle (shaft on the differential device side), and one end portion of the intermediate shaft 9 is connected to the inner ring 14 thereof. A spline portion 16 is formed on the outer ring 15 to be connected to the transaxle. The other constant velocity joint 11 is a fixed type constant velocity joint having a large allowable bending angle for connecting to a drive wheel (shaft on the front wheel side) that also serves as a steering wheel. An inner shaft 17 includes an intermediate shaft. 9 is spline-coupled, and a spline portion 19 is formed on the outer ring 18 for connection to the drive wheel. The boots 12 and 13 hold the lubricant inside the constant velocity joints 10 and 11 and prevent foreign matters from entering from the outside.

  The intermediate shaft 9 is formed with a hollow portion 20 having a large diameter and an elliptical cross section perpendicular to the rotation axis at the center other than both ends to which the constant velocity joints 10 and 11 are connected, and a small diameter and a rotation axis at both ends. Joint portions 21 and 22 having a circular cross-sectional shape orthogonal to are formed. That is, the hollow portion 20 is formed so as to extend in the axial direction in the entire inside of the intermediate shaft 9 other than both ends to which the constant velocity joints 10 and 11 are connected, and an arbitrary cross-sectional shape thereof is orthogonal to the rotation axis. The cross section has an elliptical shape having substantially the same shape and the same size. Spline portions 21 </ b> A and 22 </ b> A for coupling to the inner rings 14 and 17 of the constant velocity joints 10 and 11 are formed at the distal ends of the joint portions 21 and 22. The intermediate shaft 9 can be manufactured, for example, as follows. Both ends of the pipe member having a hollow circular cross section are drawn to form joint portions 21 and 22 having a small diameter, and the central portion (portions other than the joint portions 21 and 22 at both ends) is pressed almost uniformly from the outside in the diameter direction. Thus, the hollow portion 20 having an elliptical cross-sectional shape is formed. And spline part 21A, 22A is formed in the both ends of the joint parts 21 and 22, and the joint parts 21 and 22 are induction-hardened.

Next, the operation of the present embodiment configured as described above will be described.
The drive shaft 8 is mounted on a vehicle with a constant velocity joint 10 on one end side connected to a transaxle and a constant velocity joint 11 on the other end side connected to a drive wheel, and transmits drive torque from the transaxle to the drive wheel. . At this time, vibration caused by the meshing of the gears inside the transaxle is transmitted to the drive shaft 8.

  Since the hollow portion 20 having a large-diameter elliptical cross section is formed in the middle portion of the intermediate shaft 9, as shown in FIG. 4, the peak of the bending resonance frequency is one in the case of a circular cross section. While being separated into two, the resonance magnification is reduced. Accordingly, by appropriately setting the ratio of the major axis a and the minor axis b of the elliptical cross section so that the resonance magnification becomes lower with respect to the vibration frequency transmitted from the transaxle, the resonance is suppressed and transmitted to the vehicle body. Vibration and noise can be reduced, and the riding comfort of the vehicle can be improved.

  FIG. 4 shows the result of simulating the change in bending resonance frequency due to the solid cross-sectional shape of the shaft for convenience, and in FIG. 4, the curve (A) shows the bending resonance frequency in the case of a circular cross-section, Curves (B), (C), and (D) show the bending resonance frequency when the ratio of the major axis to the minor axis is an elliptical cross section of 1.1, 1.2, and 1.3, respectively. As can be seen from FIG. 4, in the circular cross section, the bending resonance frequency has one peak and the resonance magnification is large, whereas in the elliptic cross section, the bending resonance frequency is separated into two peaks, and the resonance magnification is obtained. In addition, as the major axis a is increased, one peak frequency is increased. Based on this simulation result, the ratio of the major axis a and the minor axis b of the elliptical cross section is appropriately set (generally, the frequency at which the resonance magnification between the two peaks is the smallest is the vibration frequency or other transmission resonance). By setting the frequency to coincide with the frequency), it is possible to effectively suppress resonance and reduce the generation of vibration and noise.

  Next, the vibration reduction effect when the drive shaft 8 is mounted on an actual vehicle will be described with reference to FIG. FIG. 5 shows the measurement of the vibration of the shock absorber upper end mounting portion of the vehicle body in a running vehicle. In FIG. 5, the curve (A) shows the case of a drive shaft having a solid circular cross section. B) shows the case of the drive shaft 8 having a hollow elliptical cross section according to the present embodiment. It can be seen from FIG. 5 that the vibration peak can be reduced by using the drive shaft 8 of the present embodiment.

  Such a vibration damping effect eliminates the need for vibration damping means such as a conventional dynamic damper and reduces the number of parts, thereby reducing the number of assembling steps and the manufacturing cost. Further, by making the intermediate shaft 9 have a hollow elliptical cross section, it is possible to enhance the vibration damping effect while minimizing the mounting space and weight increase as compared with the conventional example. At this time, by changing the ratio of the major axis “a” and the minor axis “b” of the elliptical cross section, the characteristic of the bending resonance frequency of the intermediate shaft 9 can be changed according to the vibration frequency transmitted to the intermediate shaft 9 and the natural frequency of the suspension device. It can be easily controlled.

  Further, by making the intermediate shaft 9 hollow, it is possible to reduce the weight and improve the torsional rigidity as compared with the case of the solid case. Therefore, characteristics such as the weight of the intermediate shaft 9, the torsional rigidity, the bending resonance frequency, etc. The control range can be expanded. As a result, the versatility of the intermediate shaft 9 can be improved, and the conventional use of a shaft having different characteristics depending on the wheel weight difference, vehicle type, etc. due to aluminum wheels, steel wheels, etc. The design and manufacturing costs can be greatly reduced.

The hollow portion of the intermediate shaft 9 20, by pressing the pipe member of circular cross-section from its diameter Direction outer, it is possible to easily form the cross-sectional shape oval, if in the conventional real non-circular cross-section Therefore, machining such as cutting necessary for manufacturing is unnecessary, and the manufacturing cost is low. Further, since the hollow portion 20 is formed into an elliptical shape by cold working, the strength is increased by work hardening and no quenching is required. Therefore, it is only necessary to quench the joint portions 21 and 22 at both ends, and the induction hardening is easily performed. can do.

  Next, a modification of the present embodiment will be described with reference to FIGS. In addition, with respect to the embodiment shown in FIG. 1, the same reference numerals are given to the same parts, and only different parts will be described in detail. In the modification shown in FIG. 2, the hollow portion 20 and the joint portions 21 and 22 of the intermediate shaft 9 are separated and joined by friction welding or the like. In the modification shown in FIG. 9, one joint portion 21 is separated and joined to the hollow portion 20 by friction welding or the like. Thereby, the effect | action and effect similar to what is shown in FIG. 1 can be show | played.

  In the above embodiment, the case where the present invention is applied to a drive shaft for driving front wheels of an automobile is described as an example. However, the present invention is not limited to this, and a four-wheel drive vehicle based on a front wheel drive vehicle, Alternatively, the present invention can be similarly applied to a drive shaft for driving rear wheels such as a midship vehicle.

It is a figure which shows the cross-sectional shape of the drive shaft which concerns on one Embodiment of this invention, and its hollow part. It is a figure which shows the modification of the drive shaft which concerns on one Embodiment of this invention. It is a figure which shows the other modification of the drive shaft which concerns on one Embodiment of this invention. It is a graph which shows the change of the bending resonant frequency by the cross-sectional shape in a solid shaft. It is a graph which shows the vibration reduction effect in the actual vehicle mounting state of the drive shaft shown in FIG. It is a figure which shows the conventional drive shaft. It is a longitudinal cross-sectional view of the dynamic damper with which the conventional drive shaft shown in FIG. 6 is mounted | worn. It is a figure which shows the cross-sectional shape of the shaft part of the drive shaft which has the conventional non-circular cross section.

Explanation of symbols

8 drive shaft (vehicle drive shaft), 9 intermediate shaft, 10, 11 constant velocity joint, 20 hollow part

Claims (2)

In the drive shaft for a vehicle in which constant velocity joints are connected to both ends of the intermediate shaft and are respectively connected to the shaft on the differential device side and the shaft on the wheel side,
The intermediate shaft is formed of a pipe material having a hollow portion having an elliptical cross section perpendicular to the rotation axis, and the hollow portion is a shaft in the entire interior other than both ends to which the constant velocity joint of the intermediate shaft is connected. extends in the direction, Ri elliptical der any cross-section substantially the same shape and substantially the same size perpendicular to the axis of rotation,
The both end portions have a circular cross section perpendicular to the rotation axis, and have a diameter smaller than the diameter of the portion where the hollow portion is formed,
The intermediate shaft is formed by drawing and quenching a pipe material having a circular cross section at both ends, and the hollow portion is cold processed by pressing the pipe material having a circular cross section from the outside in the diameter direction. The vehicle drive shaft is formed in an elliptical shape . A constant velocity joint is connected to both ends of the intermediate shaft, and is a method of manufacturing a vehicle drive shaft that is coupled to a differential device side shaft and a wheel side shaft, respectively .
The intermediate shaft is formed of a pipe material having a hollow portion having an elliptical cross section perpendicular to the rotation axis, and the hollow portion is a shaft in the entire interior other than both ends to which the constant velocity joint of the intermediate shaft is connected. Arbitrary cross sections extending in the direction and orthogonal to the rotation axis are substantially the same shape and substantially the same size elliptical shape,
The both end portions have a circular cross section perpendicular to the rotation axis, and have a diameter smaller than the diameter of the portion where the hollow portion is formed,
The step of forming the intermediate shaft includes reducing the diameter of both ends of the pipe member having a circular cross section by drawing, quenching to form the both ends, and pressing the intermediate portion from the outside in the diameter direction to perform cold working. The manufacturing method of the drive shaft for vehicles characterized by including the process of forming in the elliptical shape and shape | molding the said hollow part .

Images