JP2014037856A - Vibration reducing structure for final drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration reducing structure for a final drive device capable of reducing vibrations due to the engagement of a final gear, and suppressing noise in a vehicle chamber which is generated by transmitting the vibrations from an axle housing to a vehicle body frame through a suspension.SOLUTION: A pinion shaft 9 is rotatably supported in a rear axle housing 6 suspended from a vehicle body frame 1 through a suspension 7, and a pinion gear 9a provided on the pinion shaft 9 is engaged with a ring gear 13, thereby transmitting driving force inputted from an engine 2 side to the pinion shaft 9 to right and left driving wheels 8 through the pinion gear 9a and the ring gear 13. On a rear end surface of the pinion gear 9a, a hole 17 is bored and extended along an axis L1 of the pinion shaft 9. A vibration isolating rubber 18 is arranged in the hole 17 as a vibration isolating material.

Description

  The present invention relates to a vibration reduction structure of a final drive device, and more particularly to a vibration reduction structure of a final drive device that suppresses vibration caused by meshing of a final gear and suppresses vehicle interior noise.

  For example, in a truck, the driving force from the engine is transmitted to the final drive device via the transmission device and the propeller shaft, and after being decelerated by the final gear in this final drive device, it is transmitted to the left and right rear wheels via the differential mechanism. ing. The final gear is composed of a pinion gear provided at the rear end of the propeller shaft and a ring gear provided in the differential device, and transmits the rotation of the propeller shaft to the differential mechanism side while meshing with each other. The vibration generated by the engagement of the two gears is transmitted to the propeller shaft side, and the propeller shaft manufactured from the hollow pipe generates diffused sound due to the vibration, which is one of the factors increasing the vehicle interior noise.

Therefore, various countermeasures for suppressing such diffused sound from the propeller shaft have been proposed. For example, in the technique disclosed in Patent Document 1, vibration is reduced by disposing a dynamic damper on the outer periphery of the propeller shaft.
Apart from this, measures (hereinafter referred to as the prior art) for reducing the diffused sound by enclosing paper or urethane foam as a vibration-proofing material in the hollow pipe of the propeller shaft are also being implemented.

Japanese Patent Laid-Open No. 11-351247

In the technique of Patent Document 1 and the prior art described above, the vehicle interior noise caused by the diffused sound from the propeller shaft can be suppressed, but the vehicle interior noise generated due to the engagement of the final gear is the diffused sound of the propeller shaft. not only.
As is well known, since the rear axle housing of the final drive device is suspended on the vehicle body frame via the left and right suspensions, the vibration generated by the meshing of the final gear is transmitted from the rear axle housing to the vehicle body frame via the suspension, Noise. For example, in a vehicle such as a bus in which a passenger compartment is located immediately above a rear axle housing, vibration from the rear axle housing is transmitted to the passenger compartment with almost no attenuation.

  The present invention has been made to solve such problems. The object of the present invention is to reduce the vibration caused by the meshing of the final gear, and this vibration is transmitted from the axle housing to the vehicle body frame via the suspension. An object of the present invention is to provide a vibration reduction structure of a final drive device that can suppress vehicle interior noise generated by transmission.

  As described above, according to the vibration reducing structure of the final drive device of the first aspect of the present invention, the pinion shaft is rotatably supported in the axle housing suspended by the suspension from the vehicle body frame, and the pinion gear provided on the pinion shaft In the final drive device that transmits the driving force from the driving power source side to the left and right driving wheels by meshing with the ring gear, a hole is formed in at least the pinion gear region in the axial direction of the pinion shaft, and the vibration isolating material is formed in the hole Arranged.

According to a second aspect of the present invention, in the first aspect, the vibration isolating material is an anti-vibration rubber disposed in the hole of the pinion shaft.
According to a third aspect of the present invention, in the first aspect, the vibration isolating material is oil sealed in the hole of the pinion shaft.

In order to achieve the above object, a first aspect of the present invention is to rotatably support a pinion shaft in an axle housing suspended via a suspension with respect to a vehicle body frame, and to connect a pinion gear provided on the pinion shaft to a ring gear. In the final drive device that engages and transmits the driving force input to the pinion shaft from the driving power source side to the left and right drive wheels via the pinion gear and ring gear, a hole is formed at least in the pinion gear region in the axial direction of the pinion shaft However, a vibration isolator is disposed in the hole.
Therefore, the vibration generated by the engagement of the pinion gear and the ring gear during the operation of the final drive device is absorbed by the vibration isolating material, and the vibration transmitted from the axle housing to the vehicle body frame via the suspension is reduced. As a result, noise generated in the passenger compartment can be suppressed.

According to the vibration reduction structure of the final drive device of the second aspect of the invention, in addition to the first aspect, the vibration-proof material is the vibration-proof rubber disposed in the hole of the pinion shaft. Vibration can be effectively absorbed by the anti-vibration rubber.
According to the vibration reducing structure of the final drive device of the third aspect of the present invention, in addition to the first aspect, since the vibration isolating material is oil sealed in the hole of the pinion shaft, the vibration generated by the gear meshing is Can be effectively absorbed.

It is a top view which shows the vehicle body frame of the truck of embodiment. It is sectional drawing which shows the detail of a final drive apparatus. It is sectional drawing which shows the detail of the final drive apparatus of another example.

Hereinafter, an embodiment in which the present invention is embodied in a vibration reduction structure of a final drive device for a truck will be described.
FIG. 1 is a plan view showing a vehicle body frame of a truck according to this embodiment, and the left side in the figure corresponds to the front side of the vehicle. In the following, for convenience of explanation, the left-right direction in FIG.

  The body frame 1 of the truck is configured as a so-called ladder frame, and an engine 2 (driving power source) and a transmission device 3 are mounted on the front portion of the body frame 1. A propeller shaft 4 extends rearward from the transmission device 3, and a final drive device 5 is connected to the rear end of the propeller shaft 4. The left and right ends of the final drive device 5 are suspended from leaf-type suspensions 7 provided on the vehicle body frame 1, and rear wheels 8 (drive wheels) are respectively attached.

FIG. 2 is a cross-sectional view showing details of the final drive device 5. The rear axle housing 6 of the final drive device 5 is configured by fastening a first housing member 6a (shown by a solid line) and a second housing member 6b (shown by a two-dot chain line) with a bolt (not shown). The member 6b extends in the left-right direction as described above and is suspended from the suspension 7.
A pinion shaft 9 is rotatably supported by a bearing 10 in the first housing member 6a. A front end of the pinion shaft 9 projects forward from the first housing member 6a and is connected to a rear end of the propeller shaft 4. . The driving force from the engine 2 is input to the pinion shaft 9 via the transmission device 3 and the propeller shaft 4, and the pinion shaft 9 is rotationally driven about the axis L1.

  A differential case 11 is rotatably supported by a bearing 12 in the second housing member 6b, and a ring gear 13 is fixed to the differential case 11. The ring gear 13 meshes with a pinion gear 9 a formed integrally with the rear end of the pinion shaft 9 to constitute a final gear. The driving force from the engine 2 is transmitted to the differential case 11 via the pinion gear 9a and the ring gear 13, and the differential case 11 is rotationally driven about the axis L2. A pair of pinion gears 14 is rotatably supported on the differential case 11, and a pair of left and right side gears 15 rotatably supported in the differential case 11 are engaged with the both pinion gears 14 to constitute a differential mechanism.

Drive shafts 16 are disposed on the left and right sides of the differential mechanism, respectively, and these drive shafts 16 extend leftward and rightward in the second housing member 6b. The inner end of the drive shaft 16 is splined to the left and right side gears 15, and although not shown, a hub is provided at the outer end of the drive shaft 16 to which the rear wheels 8 of the vehicle are attached. Therefore, when the differential case 11 rotates together with the ring gear 13, the rotation is transmitted to the left and right side gears 15 via the pinion gear 14, and further transmitted to the left and right rear wheels 8 while allowing the differential via the drive shaft 16. .
Note that oil is stored in the rear axle housing 6, and gears and bearings are lubricated by the oil.

  The final drive device 5 is configured as described above, and the driving force of the engine 2 is transmitted to the rear wheel 8 side through the pinion gear 9a and the ring gear 13 while the vehicle is traveling. As described in [Problems to be Solved by the Invention], the vibration generated by the meshing of the pinion gear 9a and the ring gear 13 is transmitted from the rear axle housing 6 to the vehicle body frame 1 via the suspension 7 to be noise in the vehicle interior. Therefore, the technique of Patent Document 1 and the prior art that take measures against the propeller shaft 4 cannot obtain the noise suppression effect.

  In view of such a problem, the present inventor has found a countermeasure for reducing vibration itself generated at the meshing position of both the gears 9a and 13 serving as a vibration source, instead of preventing transmission of the generated vibration. That is, if the vibration generated at the meshing location can be reduced, both the vibration transmitted to the vehicle body frame 1 via the suspension 7 and the vibration transmitted to the propeller shaft 4 side are reduced. The resulting vehicle interior noise can be suppressed together. From this point of view, in the present embodiment, measures are taken for the pinion shaft 9 for the purpose of reducing vibrations generated at the meshing points, and the configuration thereof will be described below.

A hole 17 having a circular cross section is formed in the rear end surface of the pinion gear 9 a of the pinion shaft 9. The hole 17 extends forward along the axis L1 of the pinion shaft 9, and extends not only in the region of the pinion gear 9a but also in the vicinity of the rear portion of the pinion shaft 9 which is the rear position in the direction of the axis L1. Since the pinion gear 9a has a larger diameter than that of the pinion shaft 9, the inner diameter of the hole 17 is correspondingly larger than the other portions in the region corresponding to the pinion gear 9a.
In the hole 17 of the pinion shaft 9, an anti-vibration rubber 18 is disposed without a gap as an anti-vibration material. Therefore, the region of the vibration isolating rubber 18 in the direction of the axis L1 corresponds to the region where the hole 17 is formed, and the vibration isolating rubber 18 is disposed from the rear end surface of the pinion gear 9a to the vicinity of the rear portion of the pinion shaft 9. Has been.

Various methods can be applied to dispose the vibration isolating rubber 18 in the hole 17. For example, the anti-vibration rubber 18 may be molded into a shape corresponding to the hole 17 and press-fitted into the hole 17, or the anti-vibration rubber 18 may be filled into the hole 17 by vulcanization molding with the pinion shaft 9 alone. May be.
Further, as described below, the anti-vibration rubber 18 is required to have a sufficient vibration absorbing action in order to achieve vibration reduction by absorbing the vibration generated at the gear meshing position, and the oil temperature (in the rear axle housing 6 ( Therefore, the anti-vibration rubber 18 is not limited to a specific material as long as it has these required characteristics. For example, natural rubber, synthetic rubber Various materials such as rubber and elastomer can be used.
Since the surface of the pinion shaft 9 has been subjected to carburizing and quenching treatment, no problem of strength occurs even if the cross-sectional area of the pinion shaft 9 is reduced by forming the holes 17.

As described above, the vibration isolating rubber 18 disposed in the hole 17 of the pinion shaft 9 absorbs the vibration generated by the engagement of the pinion gear 9a and the ring gear 13 during the operation of the final drive device 5. Therefore, vibration transmitted to the vehicle body frame 1 via the suspension 7 is reduced, and vibration transmitted to the propeller shaft 4 side is also reduced, so that noise generated in the vehicle interior due to these vibrations can be reliably ensured. Can be suppressed.
In addition, since the inner diameter of the hole 17 is larger than other portions in the region corresponding to the pinion gear 9a, more vibration-proof rubber 18 is disposed in the vicinity of the gear meshing portion that is the vibration source. . Therefore, the vibration absorbing effect is effectively exhibited by the anti-vibration rubber 18, and the vibration can be reduced more reliably and the noise in the vehicle cabin can be achieved more reliably.

  On the other hand, a simple structure in which the vibration isolating rubber 18 for absorbing vibration is disposed in the hole 17 of the pinion shaft 9, more specifically, the hole 17 is formed in the pinion shaft 9 to press fit the vibration isolating rubber 18. Since it is a simple configuration only by vulcanization molding, it can be carried out at a very low cost without complicating the manufacturing process of the final drive device 5.

By the way, although the vibration isolating rubber 18 is used as the vibration isolating material in the present embodiment, the present invention is not limited to this, and can be arbitrarily changed as long as the above requirements for vibration absorption and heat resistance are satisfied. Therefore, for example, a highly viscous oil may be used as a vibration isolator.
For example, as shown in FIG. 3, high-viscosity oil 21 may be injected into the hole 17 of the pinion shaft 9, and the oil 21 may be sealed by closing the opening of the hole 17 with a lid 22. The enclosed oil 21 has the same vibration absorbing action as that of the anti-vibration rubber 18, and although not redundantly explained, the same action and effect as in the above embodiment can be obtained.

Although description of embodiment is finished above, the aspect of this invention is not limited to these embodiment. For example, in the above embodiment, the vibration reduction structure of the final drive device 5 for a truck is embodied, but the vehicle to be applied is not limited to this and can be arbitrarily changed. Therefore, for example, the vibration reduction structure of the front drive or rear drive final drive device of the rear wheel 2-axis type truck may be used, or the vibration reduction structure of the final drive device mounted on the bus may be used.
In the above embodiment, the anti-vibration rubber 18 is extended to the rear not only along the region of the pinion gear 9a but also along the axis L1, but this is not restrictive. The anti-vibration rubber 18 may be disposed at least in the region of the pinion gear 9a in the direction of the axis L1, and thereby noise suppression can be achieved by absorbing vibration caused by meshing.

1 Body frame 2 Engine (driving drive source)
5 Final drive device 6 Rear axle housing 7 Suspension 8 Rear wheel (drive wheel)
9 Pinion shaft 9a Pinion gear 13 Ring gear 17 Hole 18 Anti-vibration rubber (anti-vibration material)
21 Oil (anti-vibration material)

Claims (3)

A pinion shaft is rotatably supported in an axle housing suspended via a suspension with respect to the vehicle body frame, and a pinion gear provided on the pinion shaft is engaged with a ring gear so that the pinion shaft is connected from the driving power source side. In the final drive device that transmits the driving force input to the left and right driving wheels via the pinion gear and the ring gear,
A vibration reduction structure for a final drive device, wherein a hole is formed in a region of the pinion gear in at least the axial direction of the pinion shaft, and a vibration isolating material is disposed in the hole.   2. The vibration reducing structure for a final drive device according to claim 1, wherein the vibration isolating material is a vibration isolating rubber disposed in a hole of the pinion shaft.   2. The vibration reducing structure of a final drive device according to claim 1, wherein the vibration isolator is oil sealed in a hole of the pinion shaft.

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