Structure of bracket of inner-shaft bearing

An inner-shaft bearing bracket structure may include an inner-shaft that may be installed between a differential gear or a reduction gear connected to a motor or a engine for generating rotational power of a vehicle and a drive shaft for transmitting the rotational power to wheels of the vehicle in a vehicle width direction, bearings which wrap an outer peripheral surface of the inner-shaft and to which the inner-shaft may be rotatably coupled, and a bearing bracket which connects a pipe that houses and supports the bearings therein and a boss formed in the motor to project forward, wherein the bearing bracket may be disposed on a side surface of the boss and may be coupled by bolts in the vehicle width direction of the vehicle body.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2013-115464 filed on Sep. 27, 2013, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND

1. Field of the Invention

The present invention relates to an inner-shaft bearing bracket structure, and more particularly, to an inner-shaft bearing bracket structure in which a bearing bracket is disposed on a side surface of a boss and coupled to the bearing bracket by bolts in the vehicle width direction of a vehicle body, thereby improving dynamic stiffness and natural frequency of the bearing bracket to solve problems of noise vibration and harshness (NVH) of the vehicle.

2. Description of Related Art

In general, a vehicle has a drive shaft installed between a transmission and wheels, and driving force of an engine is increased or decreased through the transmission and then is transmitted to the wheels through the drive shaft to propel the vehicle.

However, when the driving force of the engine increased or decreased simply through the transmission is transmitted to the wheels of the vehicle via the drive shaft, steering stability of the vehicle is lowered due to a difference in frictional force between the left and right wheels depending on ground states and a difference in rotational speed between left and right wheels generated during rotation of the vehicle.

In order to correct these problems, a differential gear adapted to adjust the rotational speed of the left and right wheels is installed between the drive shaft and the transmission to improve steering performance and allows a safe driving when driving on an uneven road or when turning.

Further, in the case of an electric vehicle, a power source of a battery is converted into rotational mechanical force in the motor and is transmitted to the reduction gear, and finally drives the wheels via the drive shaft, thereby propelling the vehicle.

The differential gear of the general vehicle or the reduction gear of the electric vehicle cannot be installed in an intermediate portion of the vehicle due to space constraints of the engine or the motor and is biasedly installed on one side, thereby lengths of the drive shafts of the left and right wheels are applied in a different manner, and a difference in balance occurs between the left and right wheels, which becomes a factor of degradation of riding comfort and drivability.

In recent years, in order to be able to apply the same length of left and right drive shafts in view of riding comfort and drivability of the vehicle, an inner-shaft is installed between the drive shafts and a power train to form a balance between the left and right wheels.

As shown inFIGS. 1 and 2, the inner-shaft1is coupled to bearings2, a pipe3, and a bearing bracket4, and the bearing bracket4is fastened to a projecting boss5by an upper front bolting structure.

However, since the upper front bolting fastening structure applied to the conventional inner-shaft bearing bracket structure is in a form of a cantilever, there is a problem of an occurrence of noise and vibration NVH of a vehicle due to insufficient rigidity, low natural frequency, and weak dynamic stiffness, and specifically, there are problems in that an idling sound of a D stage is rough according to a specific vehicle model, vibration of the vehicle body excessively occurs, and vibration during acceleration occurs due to resonance of the bearing bracket.

As shown inFIGS. 2aand 2b, although it is possible to improve such problems by applying a front upper and lower fastening structure having the bearing brackets4formed on both sides of the pipe3, the conventional integrated inner-shaft bearing bracket structure requires a process of rotating the bearing bracket4for adjusting the engagement position between the bearing brackets4and the boss5, and at this time, there is a problem of assembling properties in that the bearing bracket4is caught by interference of the boss5at the time of application to the front upper and lower front fastening structure.

In addition, when fastening the bearing bracket and the boss while omitting the process of rotating the bearing bracket due to the problem of assembling properties of the bearing bracket, there is a problem of an occurrence of interference between the parts for arranging the inner-shaft and the bearing bracket.

In addition, conventionally, the inner-shaft bearing bracket structure has been constituted in a separation type in which the fastening points of the bearing bracket are added to a lower part as well as an upper part, and that the bearing bracket is separated or the bearing bracket and the bearings are separated from each other, thereby improving the dynamic stiffness of the vehicle, and improving the problem of assembling properties of the bearing bracket.

However, there have been problems in that the production costs of the vehicle increase due to increases in the number of components and the working steps, a vehicle weight increases, and assembling characteristics are disadvantageous compared to a case where the bearing bracket is integrally formed.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing an inner-shaft bearing bracket structure in which a bearing bracket is disposed on a side surface of a boss and is coupled by bolts in the vehicle width direction of a vehicle body to improve a problem of assembling properties of the bearing bracket, and which includes a knock bush press-fitted to the side surface of the boss to partially protrude to improve the problem of misalignment of the inner-shaft.

In an aspect of the present invention, an inner-shaft bearing bracket structure may include an inner-shaft that is installed between a differential gear or a reduction gear connected to a motor or a engine for generating rotational power of a vehicle and a drive shaft for transmitting the rotational power to wheels of the vehicle in a vehicle width direction, bearings which wrap an outer peripheral surface of the inner-shaft and to which the inner-shaft is rotatably coupled, and a bearing bracket which connects a pipe that houses and supports the bearings therein and a boss formed in the motor to project forward, wherein the bearing bracket is disposed on a side surface of the boss and is coupled by bolts in the vehicle width direction of the vehicle body.

The bearing bracket may include a first bearing bracket that connects an upper boss disposed adjacent to an upper part of the pipe and the pipe, and a second bearing bracket that connects a lower boss disposed adjacent to the lower part of the pipe and the pipe.

The boss may further include a boss hole formed through the boss in the vehicle width direction, and a knock bush that may have an inner periphery of the same size as that of an inner periphery of the boss hole, and is press-fitted to the side surface of the boss to partially protrude, wherein the knock bush is fitted to the bearing bracket.

The inner-shaft bearing bracket structure may further include a boss hole formed through the boss in the vehicle width direction, and a knock bush that may have an inner periphery of the same size as that of the inner periphery of the boss hole, and is press-fitted to the side surface of the bearing bracket to partially protrude, wherein the knock bush is fitted to the boss hole.

The bearings, the pipe, and the bearing bracket are integrally formed.

The pipe and the bearing bracket are made of an aluminum material.

Effects of the present invention having the structure as described above are to allow assembling having no problem of interference between the parts for arranging the inner-shaft and the bracket without rotation of the bearing bracket, by disposing the bearing bracket on the side surface of the boss and coupling the bearing bracket by bolts in the vehicle width direction of the vehicle body.

Furthermore, there is an effect of increasing natural frequency of the bearing bracket, enhancing the dynamic stiffness, and improving the problem of noise vibration (NVH) of the vehicle, by constituting the bearing bracket to may include the first bearing bracket and the second bearing bracket and applying the upper and lower side surface fastening structure rather than the conventional upper front fastening structure.

Furthermore, there is an effect of completely removing the possibility of an occurrence of unbalance vibration of the bearing bracket, by applying an inner-shaft misalignment preventing structure that may include a knock bushing press-fitted into the side surface of the boss to partially protrude and allows the bearing bracket to be coupled to the knock bush.

Additionally, there is an effect of reducing the number of the fastening parts, reducing the weight of a vehicle, and reducing the number of working steps, by forming the pipe and the bearing bracket integrally rather than in a separation type.

Furthermore, there is an effect of being able to reduce the weight of a vehicle body, by forming the pipe and the bearing bracket to be applicable by a lightweight material, i.e., an aluminum material without deterioration of dynamic stiffness and natural frequency.

Consequently, the inner-shaft bearing bracket structure according to an exemplary embodiment of the present invention has an effect of increasing natural frequency and dynamic stiffness of the bearing bracket to improve the problem of noise and vibration of a vehicle, removing the possibility of the occurrence of unbalanced vibration of the bearing bracket by applying the inner-shaft misalignment preventing structure, and reducing the weight of the vehicle and the number of working steps.

DETAILED DESCRIPTION

Hereinafter, the present invention will be described in detail on the basis of the accompanying drawings. The differential gear of the general vehicle or the reduction gear

The inner-shaft bearing bracket structure according to an exemplary embodiment of the present invention includes an inner-shaft40installed between a differential gear or a reduction gear20connected to a engine or a motor10for generating rotational power of a vehicle and a drive shaft30for transmitting the rotational power to wheels of the vehicle in a vehicle width direction; bearings50which wrap the outer peripheral surface of the inner-shaft40and to which the inner-shaft40is rotatably coupled; and. a bearing bracket80which connects a pipe60that houses and supports the bearings50inside and a boss70formed in the engine or the motor10to project forward, wherein the bearing bracket80is disposed on the side surface of the boss70, and is coupled by bolts in the vehicle width direction of the vehicle body.

As shown inFIG. 3, in the shown embodiment, the differential gear or the reduction gear20is biasedly coupled to the left front of the engine or the motor10, the drive shaft30configured to transmit rotational power to the wheels of the vehicle is coupled to a left side based on the differential gear or the reduction gear20in the vehicle width direction, and the inner-shaft40is coupled to a right side in the vehicle width direction.

Another drive shaft30is coupled to the right side of the inner-shaft40in the vehicle width direction to transmit rotational power to the wheels of the vehicle.

That is, in view of riding comfort and the drivability of a vehicle, by applying the drive shafts30of the same length and disposing the inner-shaft40between the drive shafts30, a balance is formed between the left and right wheels.

As shown inFIG. 4, the bearings50having the inner periphery of the same size as that of the outer periphery of the inner-shaft40are coupled to the inner-shaft40such that the inner-shaft40can rotate without friction, and the pipe60having the inner periphery of the same size as that of the outer periphery of the bearings50is coupled to the bearings.

Furthermore, as shown inFIGS. 3 and 4, in the shown embodiment, a boss including a boss hole76formed to be able to be coupled to the bearing bracket80by bolts protrudes on the right front of the engine or the motor10, and the bearing bracket80is connected between the boss70and pipe60.

The bearing bracket80is disposed adjacent to the right side surface of the boss70and is coupled to the boss70by bolts through the boss hole76in the vehicle width direction. Specifically, in the shown embodiment, the bolts sequentially pass through the bearing bracket80and the boss70, and are coupled in a right-to-left direction.

Of course, the bolts can also be coupled in the left-to-right direction of the boss70, but in the shown embodiment, in view of assembling characteristics of the bearing bracket, man-hours or the like, the bolts are preferably coupled in the right-to-left direction, and on the contrary to the shown embodiment, in the structure in which the differential gear or the reduction gear20is disposed on the front right of the motor10and the boss70is disposed on the left front of the engine or the motor10, the bolts are preferably coupled in the left-to-right direction.

By coupling the bearing bracket80to the side surface of the boss70by bolts as described above, it is possible to improve the problem of assembling properties of the bearing bracket80, and it is possible to implement a structure in which the upward and downward fastening of the bearing bracket80is performed as will be described later.

As shown inFIG. 4, it is preferred that the bearing bracket80includes a first bearing bracket82that connects an upper boss72disposed adjacent to the upper part of the pipe60and the pipe60, and a second bearing bracket84that connects a lower boss74disposed adjacent to the lower part of the pipe60and the pipe60.

The first bearing bracket82and the second bearing bracket84are preferably formed in a symmetrical shape facing each other based on the inner-shaft40to be configured to be coupled to the upper boss72and the lower boss74, respectively, and are formed in a triangular form that abuts against the pipe60in the shown embodiment.

A person of ordinary skill will be appreciated that the bearing bracket80can be formed in a form of a boss, a form of an inner-shaft, and various forms in consideration of the interference element around the bearing bracket or the like.

By forming the bearing brackets80to include the first bearing bracket82and the second bearing bracket84as described above, the upper and lower fastening structure can be applied, and thus, it is possible to improve natural frequency and dynamic stiffness, thereby improving the problems of noise and vibration (NVH) of a vehicle.

As shown inFIGS. 5 and 6, it is preferred that the boss70further includes a knock bush90that has the same inner peripheral surface as the outer peripheral surface of the boss hole76, and is press-fitted to the side surface of the boss70to partially protrude.

As shown inFIG. 6, the knock bush90is formed in a ring shape having an inner periphery of the same size as that of the outer periphery of the boss hole76, a part thereof is press-fitted into the boss70, and the remaining part thereof projects to the side surface of the boss70.

Furthermore, as shown inFIG. 6, the bearing bracket80is formed with grooves having an inner periphery of the same size as that of the outer periphery of the knock bush90in response to the shape of the knock bush90to be configured to be fitted to the knock bush90.

Furthermore, although not shown, the knock bush90can be press-fitted into the side surface of the bearing bracket80to partially protrude, and in this case, the boss70is preferably formed with grooves having the inner periphery of the same size as that of the outer periphery of the knock bush90in response to the shape of the knock bush90to be configured to be fitted to the knock bush90.

Since the bearing bracket80and the boss70are coupled via the knock bush90as described above, it is possible to minimize the positional tolerance of the seating surface of the bearing bracket80, it is possible to minimize the perpendicularity tolerance of the side surface of the boss70and the upper end of the bearing bracket80, and it is possible to minimize the distance tolerance between the center of the boss hole76and the center of the pipe60.

That is, by providing the knock bush90, it is possible to apply misalignment preventing structure of the inner-shaft40to eliminate the possibility of the unbalanced vibration.

Furthermore, it is preferred that the bearing50, the pipe60, and the bearing bracket80be integrally formed.

That is, instead of separately forming the pipe60and the bearing bracket60by the individual components, it is preferred to form the pipe60and the bearing bracket80in a continuous form formed with one material, and to insert the bearings50into the inner side of the pipe60, thereby generally integrally forming the pipe60, the bearing bracket80, and the bearings50.

Furthermore, as shown inFIGS. 6 and 7, it is preferred that the bearings50be press-fitted into the inside of the pipe60by interference fit in terms of improvement of the bearing durability, and in order to prevent the bearings50from being disengaged from the pipe60after assembly, it is preferred to place a catching jaw structure62for fixing the bearings50on one side of the pipe60and to mount a stopper ring64or a snap ring or fix the bearings via a pipe caulking66or the like on the other side.

As described above, by integrally forming the bearings50, the pipe60, and the bearing bracket80, it is possible to reduce the number of parts, the manufacturing costs of a vehicle and the vehicle weight as compared to a configuration in which the bearing bracket80and the bearings50are separated from each other.

Further, it is preferred that the pipe60and the bearing bracket80be made of an aluminum material.

When conventionally applying aluminum rather than the cast iron as the materials of the pipe and the bearing bracket, it is possible to reduce the weight of a vehicle, but there is a problem in that dynamic stiffness and natural frequency are degraded.

However, since it is possible to apply to the upper and lower side surface fastening structure in the inner-shaft bearing bracket structure according to an exemplary embodiment of the present invention, it is possible to apply the lightweight material, i.e., aluminum without degradation of dynamic stiffness and natural frequency, and thus it is possible to maintain the dynamic stiffness and natural frequency while also reducing the weight of a vehicle.

It will be apparent to those skilled in the art that the present invention described above is not intended to be limited by the above-described examples and the accompanying drawings, and various substitutions, variations, and modifications can be made without departing from the technical spirit of the present invention.