JP2004190748A - Bearing structure of transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance silent operability by suppressing resonance of bending vibrations of a drive pinion shaft with gear vibrations. <P>SOLUTION: A drive shaft 1a and a drive pinion shaft 1b are arranged coaxially, and spline-coupled by a spline part 10. In the spline part 10, an inner spline is provided to an end of the drive shaft 1a. An outer spline is provided to an end of the drive pinion shaft 1b. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing structure for a transmission such as an automobile, and more particularly to a bearing structure suitable for supporting a relatively long rotating shaft.
[0002]
[Prior art]
In general, a transmission employs a gear train in which a power input portion and a power output portion are separated from each other, so that the drive pinion shaft and the like tend to be longer. For example, in the case of a vertical transmission, the optimal arrangement position of the front differential device is at the center of the vehicle on the same axis as the wheels. Therefore, the drive pinion shaft for driving the differential device arranged at the optimum position tends to be necessarily longer. The same applies to a lateral transmission, and a drive pinion shaft substantially corresponding to the entire length of the main transmission portion is often used.
[0003]
Thus, in a structure using a relatively long drive pinion shaft, bending vibration of the shaft (that is, periodic shaft displacement in the radial direction) may occur. The axial displacement in the radial direction due to the bending vibration of the shaft is transmitted to a gear attached to the end of the shaft. As a result, the gear train including this gear causes a change in tooth contact. Here, the "change in tooth contact" refers to a phenomenon in which the contact of the tooth is shifted from an ideal position and is locally and unevenly applied by tilting the axis. This change in tooth contact not only causes a reduction in transmission efficiency and wear of the gears, but also causes a gear noise in synchronization with bending vibration to cause inconvenience to the driver.
[0004]
As one method of solving such inconvenience, it is conceivable to add a bearing in the middle of the long shaft to regulate the bending vibration itself of the shaft. Patent Document 1 discloses a bearing structure in which a main shaft and a sub shaft of a transmission extend through each bearing opening using a support having a first bearing opening and a second bearing opening. Since the main shaft and the countershaft are supported by the support in the middle of both ends, the center distance between the main shaft and the countershaft is, although the separating force of the gear teeth acts laterally with respect to the shaft, It is kept the same as the center distance of the meshing gear train. Japanese Patent Application No. 2001-259705, which is a prior application of the present applicant, discloses a transmission that reduces gear noise caused by shaft vibration by suppressing tooth surface vibration of a reduction driven gear mounted on a drive pinion shaft. Is described.
[0005]
[Patent Document 1] JP-A-6-241288
[Problems to be solved by the invention]
By the way, if the gear vibration (rotational vibration and axial vibration) of the reduction driven gear itself and the vibration of the drive pinion shaft to which it is attached resonate, the vibration is amplified and a peak of gear noise may occur. is there. When such a peak occurs, silence is impaired.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to suppress the bending vibration of the drive pinion shaft from resonating with the gear vibration, and to further improve quietness.
[0008]
[Means for Solving the Problems]
In order to solve such a problem, the present invention provides a reduction driven gear, a drive shaft provided with a reduction driven gear at one end, a drive pinion shaft arranged coaxially with the drive shaft and having a hypoid pinion gear provided at one end, Provided is a bearing structure of a transmission having a spline portion that spline-couples the other end of a drive shaft and the other end of a drive pinion shaft.
[0009]
Here, in the above configuration, it is preferable that at least one of the inner spline and the outer spline constituting the spline portion is subjected to crowning. Further, the drive shaft may be spline-coupled to the reduction driven gear.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram of a main part of a vertical transmission. The drive shaft 1a and the drive pinion shaft 1b provided on the output side of the automatic transmission are coaxially arranged, and both are spline-coupled by a spline portion 10. At one end of the drive shaft 1a, a reduction driven gear 2b as a helical gear is integrally provided. A hypoid pinion gear 3 meshed with the hypoid ring gear is provided at one end of the drive pinion shaft 1b. A relatively large driving force shifted by a transmission mechanism (not shown) in the transmission is transmitted to a drive shaft 1a via a reduction driven gear 2b meshed with a reduction drive gear 2a, and then transmitted to a drive pinion via a spline portion 10. It is transmitted to the shaft 1b. The driving force of the drive pinion shaft 1b is transmitted to the wheels via a hypoid ring gear meshed with the hypoid pinion gear 3.
[0011]
Due to the relationship with the optimum arrangement position of the differential device 7, the combined shaft length of the drive shaft 1a and the drive pinion shaft 1b tends to be longer. In this transmission, the total length of the two shafts 1a and 1b arranged coaxially is mainly constituted by a main transmission section (not shown) located above them (that is, a multi-disc clutch, a multi-disc brake, a planetary and the like). Is longer than the entire length of the portion where the transmission mechanism is located).
[0012]
An end of the drive shaft 1a on the reduction driven gear 2b side is supported by a pair of ball bearings 5a, 5b disposed near the driven gear 2b. That is, on the outer periphery of the reduction driven gear 2b, there are provided a fixed portion 2c extending inward in the axial direction around the gear 2b and a fixed portion 2d extending outward in the axial direction. The inner ring of the ball bearing 5a whose outer ring is fixed to the transmission case is fixed to the axially inner fixing portion 2c. On the other hand, the inner race of the ball bearing 5b whose outer race is fixed to the transmission case is fixed to the axially outer fixing part 2d. These ball bearings 5a and 5b are ordinary deep groove ball bearings, and function as thrust bearings for applying a thrust load parallel to the axis of the two shafts 1a and 1b. On the other hand, an end of the drive pinion shaft 1 b on the side of the hypoid pinion gear 3 is supported by a double row tapered roller bearing 4 disposed near the pinion gear 3. The double-row tapered roller bearing 4 has an inner ring fixed to the drive pinion shaft 1b and an outer ring fixed to the transmission case by bolts. A plurality of tapered rollers are interposed in the space between the inner and outer rings.
[0013]
In the spline portion 10 in which the two shafts 1a and 1b are spline-coupled, an inner spline is provided at an end of the drive shaft 1a, and an outer spline is provided at an end of the drive pinion shaft 1b. The inner and outer splines are crowned as shown in FIG. The normal spline is processed so that the tooth trace is straight as shown by the two-dot chain line in FIG. On the other hand, the spline subjected to crowning is processed into a tooth trace having an appropriate bulge along the tooth trace as shown by a solid line in FIG. When such crowning is applied to the outer spline, first, the arc shape of the outer diameter is given by a blank shape before gear cutting or by grinding after heat treatment. The crowning of the tooth muscle can be formed by shaving after forming a straight tooth surface. The drive shaft 1a is spline-connected to the reduction driven gear 2b by a spline portion 6. An outer spline is provided at the end of the drive shaft 1a, and an inner spline is provided at the reduction driven gear 2b.
[0014]
As described above, in the present embodiment, the two shafts 1 a and 1 b arranged coaxially are spline-coupled by the spline portion 10. Generally, the spline connection has a vibration damping action due to contact, surface pressure, friction, and the like at the connection portion. Therefore, by coupling the drive shaft 1a, the drive pinion shaft 1b, and the spline portion 10 via the spline portion 10, the gear vibration transmitted from the reduction driven gear 2b to the drive shaft 1a and the two shafts 1a, 1b (the drive in the conventional bearing structure) Resonance with bending vibration at the pinion shaft). As a result, the amplification of the vibration due to the resonance of the two vibrations can be suppressed, so that the peak of the gear noise generated in synchronization with these vibrations can be reduced. FIG. 3 is an explanatory diagram of the vibration characteristics, and compares the bearing structure according to the present embodiment with the conventional bearing structure in terms of the vibration and noise level of gear noise. As shown in the figure, the bearing structure according to the present embodiment generally has lower vibration and noise levels and lower peaks than the conventional bearing structure. Such a reduction in the peak in the gear noise can further improve the quietness.
[0015]
Further, in the present embodiment, in the drive shaft 1a and the drive pinion shaft 1b which are spline-coupled, the tooth traces of the splines are crowned. By crowning the splines, the meshing between the splines is improved, and the vibration damping action of the spline portion 10 can be further improved. The drive shaft 1a is spline-connected to the reduction driven gear 2b by a spline portion 6. Due to the vibration damping effect of the spline portion 6, resonance between the gear vibration of the reduction driven gear 2b itself and the bending vibration of the drive shaft 1a to which the reduction driven gear 2b is attached is suppressed. Therefore, amplification of vibration due to resonance of these vibrations can be suppressed, and the peak of gear noise generated in synchronization with these vibrations can be further reduced.
[0016]
In the spline section 10 according to the present embodiment, both splines constituting the spline section 10 are crowned. However, in spline section 10, it is only necessary that at least one of the inner spline and the outer spline constituting the spline section is crowned.
[0017]
【The invention's effect】
Thus, in the present invention, the drive shaft and the drive pinion shaft are spline-coupled. Due to this spline coupling, it is possible to suppress the resonance between the gear vibration generated in the reduction driven gear and transmitted to the drive shaft and the bending vibration of the drive pinion shaft, and to suppress the amplification of the vibration due to the resonance of these vibrations. Can be. As a result, the peak of gear noise generated in synchronization with these vibrations can be reduced, and silence can be further improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of main parts of a vertical transmission. FIG. 2 is an explanatory diagram of crowning. FIG. 3 is an explanatory diagram of vibration characteristics.
1a Drive shaft 1b Drive pinion shaft 2a Reduction drive gear 2b Reduction driven gear 2c Fixed portion 2d Fixed portion 3 Hypoid pinion gear 4 Double row tapered roller bearing 5a Ball bearing 5b Ball bearing 6 Spline portion 7 Differential device

Claims (3)

In the bearing structure of the transmission,
Reduction driven gear,
A drive shaft provided with the reduction driven gear at one end,
A drive pinion shaft disposed coaxially with the drive shaft and having a hypoid pinion gear at one end;
A bearing structure for a transmission, comprising: a spline portion that spline-couples the other end of the drive shaft and the other end of the drive pinion shaft. The bearing structure of a transmission according to claim 1, wherein at least one of an inner spline and an outer spline constituting the spline portion is crowned. The bearing structure for a transmission according to claim 1, wherein the drive shaft is spline-coupled to the reduction driven gear.

Images