JP2002173034A - Mounting structure for power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent resonance of a cross member with vibration of a power steering device in a structure of mounting the power steering device for an automobile of the cross member of a body. SOLUTION: The cross member 4 is formed in a hollow shape and a foaming body 6 is filled in the cross member 4 in this mounting structure 5. The faming body 6 increases stiffness of the cross member 4 and shifts a resonance frequency for controlling vibration. It can be controlled for gear vibration or the like of the power steering device 1 to be transmitted into a passenger compartment through the cross member 4. And the foaming body is light to control weight increase. The foaming body 6 can be expanded in the cross member 4 after the cross member 4 is mounted on the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting a power steering device of an automobile to a vehicle body.

[0002]

2. Description of the Related Art As the above-mentioned mounting structure, for example, there is a structure in which a housing of a power steering device is fixed to a cross member of a frame of a vehicle body by screwing. The cross member is a metal member that is disposed at the front of the vehicle body and extends in the width direction of the vehicle body, and is generally formed in a hollow shape for weight reduction.

[0003]

However, during steering operation, gear vibration of the power steering device may be transmitted to the cross member. When the frequency of the gear vibration substantially matches the natural frequency of the cross member, the cross member resonates, and as a result, the vibration amplified by the resonance is propagated through the frame to the passenger compartment, generating large noise. There is. Further, in order to prevent vibration, it is conceivable to use a solid-shaped, high-rigidity cross member, but this is not preferable because it significantly increases the weight.

Accordingly, an object of the present invention is to solve the above-mentioned technical problem, to suppress the generation of noise in the vehicle cabin due to the power steering device, and to attach a power steering device capable of suppressing an increase in weight. Is to provide a structure.

[0005]

According to a first aspect of the present invention, there is provided a mounting structure for mounting a power steering device to a cross member of a frame of a vehicle body, wherein the cross member is formed in a hollow shape. The present invention provides a mounting structure for a power steering device, characterized by being filled with a foam. According to the present invention, by filling the foam, the rigidity of the cross member can be increased and the resonance frequency can be shifted, so that the lightweight cross member can be hardly vibrated. As a result, transmission of gear vibrations or the like of the power steering device via the cross member to, for example, the vehicle interior can be suppressed, and noise in the vehicle interior can be suppressed. Further, since the foam is lightweight, the weight increase is small.

According to a second aspect of the present invention, in the power steering device mounting structure according to the first aspect, the foam is foamed inside a cross member. I will provide a. According to the present invention, it is possible to obtain a foam filled to every corner of the interior, and this foam can contact the entire inner surface of the cross member, so that the rigidity can be further increased, which is preferable. Further, the foam may be foamed inside the cross member after being attached to the vehicle body.

According to a third aspect of the present invention, there is provided the power steering device mounting structure according to the first or second aspect, wherein the power steering device has a driving motor. provide. According to the present invention, the cross member can suppress transmission of vibration from the driving motor.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a power steering apparatus according to an embodiment of the present invention. FIG. 1 is an exploded perspective view of a mounting structure according to an embodiment of the present invention. FIG. 2 is a front sectional view of the power steering device. The power steering device 1
A steering shaft (not shown) provided at one end for transmitting a steering force, and a pinion (not shown) provided at the other end of the steering shaft 10 are drivingly connected to each other so as to be driven by the movement of the steering wheel. It has a rack shaft 11 that reciprocates to steer (not shown), and a housing 12 that accommodates and supports the rack shaft 11 so that it can reciprocate in the axial direction. The rack shaft 11 extends in the width direction of the vehicle, which is left and right with respect to the traveling direction of the vehicle, and an end of the rack shaft 11 is connected to wheels via joints, tie rods (not shown), and the like. .

The power steering device 1 includes a drive motor 20 composed of an electric motor for generating a steering assist force in accordance with an operation of a steering wheel, and a drive motor 2
And a ball screw mechanism 13 for transmitting the steering assist force of 0 to the rack shaft 11. Power steering device 1
Although not shown, a torque sensor is provided in association with the steering shaft 10 to detect the steering force, and a drive motor 20 is provided in accordance with the output of the torque sensor. And a control circuit including a microcomputer or the like for driving the microcomputer.

The drive motor 20 is provided in the middle of the rack shaft 11, and is housed in the housing 12 together with the ball screw mechanism 13. The drive motor 20 is arranged so as to surround the rack shaft 11 and is driven and connected to the rack shaft 11 via a ball screw mechanism 13. The rotor 21 concentrically surrounds the rotor 21 and is fixed to the housing 12. 22. The ball screw mechanism 13 includes a screw 14 formed on the outer peripheral surface in the middle of the rack shaft 11, a nut member 15 coaxially arranged around the screw 14, and a nut member 15.
And a number of balls 16 interposed between the screw 14. The nut member 15 is drivingly connected to one end of the rotor 21. The nut member 15 and the rotor 21
The housing 12 is supported via bearings 17, 18, and 19 so as to be rotatable concentrically with the rack shaft 11 and in a position-restricted state in the axial direction.
It is supported by.

When the steering wheel is operated, the drive motor 20 is driven in accordance with the operation. The rotational force of the motor 20 is converted into an axial force of the rack shaft 11 via the ball screw mechanism 13 to move the rack shaft 11 in the axial direction. The housing 12 includes a cylindrical portion 23 that extends in the axial direction to accommodate the rack shaft 11,
3 has a flange 24 (only a part is shown) protrudingly formed on the outer peripheral surface. The power steering device 1 is fixed to the vehicle body 2 by the mounting structure 5 including the flange 24.

In the mounting structure 5, the housing 12 of the power steering device 1 is mounted on the cross member 4 of the frame 3 of the vehicle body 2 by using screwing means. The mounting structure 5 includes a plurality of bolts 31 and nuts 32 as screwing means.
And the housing 12 through which the bolt 31 is inserted.
Of the flange 24 and the male screw of the bolt 31 inserted through the insertion hole 33 are screwed into the cross member 4.
And a screw hole 34 including a female screw formed therein.
Two sets of female screws, insertion holes 33, bolts 31, etc. are provided,
They are spaced apart in the width direction of the vehicle body 2.

In particular, in the mounting structure 5, the cross member 4
Is formed in a hollow shape, and the inside thereof is filled with a foam 6. The cross member 4 forms a part of the vehicle body 2, particularly, a part of the frame 3. The frame 3 is a frame-like structure on which an engine, a steering device, and the like are mounted, and is integrally formed by welding or the like with a body shell (not shown) of the vehicle body 2, which is a box-like structure constituting a passenger compartment or the like. It is connected to the. The shapes of the vehicle body 2 and the frame 3 are not particularly limited. For example, the frame 3 may be detachably connected to a body shell of the vehicle body 2 or the like. In addition, the vehicle body 2 may be any device as long as it supports passengers, luggage, driving equipment, and the like while being supported by a traveling device such as wheels.

The frame 3 includes a main body 7 extending in the front-rear direction of the vehicle body 2, the above-described cross member 4 extending in the left-right direction (width direction) of the vehicle body 2, and the above-mentioned filling member inside the cross member 4. And a foam 6. The cross member 4 and the foam 6 cooperate with each other to function as a support member that supports the power steering device 1. Both ends of the cross member 4 are rigidly connected to the main body 7 of the frame 3 by welding. The cross member 4 is a long member having a hollow shape, and has a substantially rectangular cross section taken along the longitudinal direction. The cross member 4 is configured by connecting, by welding, a first member 41 forming three sides of a substantially rectangular cross section and a second member 42 forming the remaining one side.

Although not particularly shown, the cross member 4 has an opening for filling the foam 6 therein.
On the other hand, the foam 6 is prevented from protruding outside. That is, both ends of the cross member 4 are covered with the main body 7 while being connected to the main body 7. Also, between the cross member 4 and the main body 7,
The space between the first member 41 and the second member 42 is sealed by a sealing means such as a sealing tape so that no gap is generated.

The foam 6 is obtained by foaming a material resin such as a polyurethane resin to generate a large number of fine bubbles in a dispersed state in the material resin.
Here, as a foaming method for foaming the material resin, a known method can be used. In addition, a known method can be used for the method of forming the foam 6. Further, as the material resin, a known synthetic resin material which can be foamed may be used in addition to the polyurethane resin. The foam 6 is foamed inside the cross member 4. When viewed in a cross section taken along the longitudinal direction of the cross member 4, the foam 6 fills the inside of the cross member 4 without gaps and is in close contact with the inner surface of the cross member 4. Also,
In the longitudinal direction of the cross member 4, the foam 6 is filled over substantially the entire length of the cross member 4. Thereby, the effect of suppressing the vibration of the cross member 4 is preferably obtained over the entire length.

As described above, according to the embodiment of the present invention, by filling the inside of the cross member 4 with the foam 6,
Since the rigidity of the cross member 4 can be increased and the resonance frequency can be shifted, the lightweight cross member 4 can be hardly vibrated. As a result, transmission of gear vibrations and the like of the power steering device 1 to the vehicle interior via the cross member 4 can be suppressed, and noise in the vehicle interior can be suppressed. Further, since the foam 6 is lightweight, the weight increase is small.

If the foam 6 is formed by foaming inside the cross member 4, the foam 6 filled to every corner inside the cross member 4 is obtained. Since the entire inner surface of the cross member 4 can be contacted, the rigidity can be further increased, which is preferable. Further, the cross member 4 filled with the foam 6 may be attached to the vehicle body 2, or the foam 6 may be foamed inside the cross member 4 after being attached to the vehicle body 2.

The cross member 4 is connected to the drive motor 20.
Since the transmission of vibration from the motor can be suppressed, the use of the drive motor 20 is substantially enabled. That is, when the cross member cannot suppress the transmission of vibration, even if the driving motor 20 is used, the vibration caused by the driving motor 20 occurs, and the power steering device 1 cannot be put to practical use. According to the present invention, the vibration can be suppressed as described above, and the driving motor 20 can be used without any problem.

For example, the vibration characteristic, which is the relationship between the acceleration of the vibration at the substantially central portion in the longitudinal direction of the cross member 4 and the frequency of the vibration with respect to the vibration during the actual steering operation, is as shown in FIG. When the vibration characteristics of the cross member 4 according to the embodiment of the present invention (see line G1) and the vibration characteristics of the conventional cross member (see line G2) are compared, the peak value of the vibration acceleration is reduced to approximately one third. It is getting smaller. Also, the frequency at which the maximum peak of the vibration acceleration occurs differs, and resonance can be effectively suppressed, especially in a low frequency range.

A so-called direct drive (D) in which the rack shaft 11 is
In the D) type electric power steering device, since the drive motor 20 is close to the cross member 4, the vibration caused by the drive motor 20 tends to easily vibrate the cross member 4. The present invention can suppress the vibration of the cross member 4 as described above, and is therefore preferable for a DD type electric power steering device.

The present invention is preferable for a so-called monocoque body type vehicle body 2 in which the frame 3 and the body shell are integrally formed by welding or the like. This is because, in the vehicle body 2 of this type, since the cross member 4 is rigidly connected to the body shell, the vibration generated in the cross member 4 is easily transmitted to the passenger compartment, and as a result, noise is easily generated. In the above-described embodiment, the power steering device 1 is of a type in which the driving motor 20 and the rack shaft 11 are coaxially arranged and are drivingly connected via the ball screw mechanism 13. Not done. For example, the power steering device 1
May be a type in which the axes of the drive motor 20 and the rack shaft 11 are spaced apart from each other, or the drive motor 20 may be provided in relation to the steering shaft 10 and the rack shaft may be connected via a pinion. 11 may be of a type that is drivingly connected to.

In addition, various design changes can be made without changing the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an attachment structure according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional front view of the power steering device of FIG. 1;

FIG. 3 is a graph of vibration characteristics showing a comparison between a mounting structure according to an embodiment of the present invention and a conventional mounting structure, wherein the horizontal axis represents vibration frequency and the vertical axis represents vibration acceleration. The characteristics of the mounting structure are indicated by a solid line G1, and the characteristics of the conventional mounting structure are indicated by a chain line G2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power steering device 2 Body 3 Frame 4 Cross member 5 Mounting structure 6 Foam 20 Drive motor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D003 AA04 AA06 AA18 BB01 CA09 DA09 3D033 AA01 CA02 CA04 JB01 5H607 AA04 BB01 CC03 DD04 DD16 EE53 GG01 GG08

Claims (3)

[Claims] 1. A mounting structure for mounting a power steering device to a cross member of a frame of a vehicle body, wherein the cross member is formed in a hollow shape, and the inside thereof is filled with a foam. Mounting structure. 2. The mounting structure for a power steering device according to claim 1, wherein said foam is foamed inside a cross member. 3. The mounting structure for a power steering device according to claim 1, wherein said power steering device has a driving motor.