KR20030039749A - Automobile Sub-frame - Google Patents

Abstract

PURPOSE: A sub-frame for a vehicle is provided to reduce booming noise of the room of the vehicle by effectively absorbing vibration produced from an engine and a power train, with the sub-frame, and by preventing the vibration from being transmitted to a vehicle body. CONSTITUTION: In a sub-frame(20) for a vehicle, a dynamic damper(30) is installed at the ends of an opened portion of the sub-frame, through vibration absorbing members(31), and an engine and a power trains are supported on a side of the sub-frame and a side of the dynamic damper. The dynamic damper is disposed in the front or rear side of the vehicle body, to absorb bouncing vibration and pitching vibration of the sub-frame. Accordingly, noise of the room of the vehicle is sharply reduced.

Description

Automotive subframes {Automobile Sub-frame}

The present invention relates to a vehicle subframe, and more particularly, to a vehicle in which the booming noise in the cabin is reduced by effectively absorbing the vibration generated from the engine and the power train to prevent the vibration from being transmitted to the vehicle body. It relates to a subframe.

As shown in FIG. 1, the subframe is a “ㅁ” shaped structure installed at the bottom of the front of the vehicle body. The subframe generally includes components and suspensions of a power transmission system such as an engine or a power train mounted in an engine room. Installed to support, bolts and nuts are used a lot in the mounting portion for fastening the subframe 10 to the front side member of the vehicle body.

FIG. 2 is a plan view showing a state in which an engine is mounted on a conventional automobile subframe, and as shown here, the conventional subframe 10 is a “ㅁ” shaped structure, and includes a front side member ( A plurality of fastening holes 10a are formed to be fastened to the vehicle (not shown) and are usually fixed to the vehicle body through bolts.

In particular, the engine 1 and the power train 2 are installed above the subframe 10, and the engine 1 and the power train 2 can absorb the vibrations before and after the subframe 10. Two-point mounting and two sides 1a, 2a of the engine 1 and powertrain 2 are mounted to the body.

In addition, the vibration generated in the engine 1 and the powertrain 2 is primarily absorbed by the subframe 10 and the mounted engine mounting bush 11, but the residual vibration energy has the subframe 10. Done. The subframe 10 is subjected to the natural vibration of the form as shown in Figure 3 by this excitation force.

As shown in FIG. 3, the subframe 10 has different vibration modes according to the change in the frequency, each of which has a bouncing mode in which the structure of the subframe 10 vibrates up and down, A mode), a rolling mode (B mode) that rotates and oscillates about the x-axis, which is the longitudinal direction of the subframe, a pitching mode (C mode) that rotates and oscillates about the y-axis, and the subframe The structure itself is divided into a torsion mode (D mode) in which bending and torsional vibrations occur.

The subframe having the four vibration types as described above is amplified by the natural frequency of the subframe itself, the amplified vibration is transmitted to the vehicle body to vibrate the vehicle body.

At this time, when the subframe frequency is vibrated at the same frequency as the cavity sound pressure frequency in the vehicle compartment, a resonance phenomenon occurs in which the amplitude of the sound pressure frequency of the vehicle vehicle becomes very large. This is caused by the bouncing mode and the pitching mode of the frame, which causes a problem in that the booming noise in the vehicle is very large.

The bouncing noise here is the “loud” distance generated in the cabin, and when the passenger is exposed to this bouncing noise for a long time, the ears are blunt and very tired.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above problems, and an object thereof is to reduce bouncing noise in a vehicle by suppressing bouncing and pitching modes, which are natural vibration modes of subframes vibrated by an engine and a power train. The present invention provides a subframe for an automobile.

1 is a perspective view of a typical vehicle in which a subframe is mounted;

2 is a plan view showing a state in which the engine is mounted on a conventional vehicle subframe,

3 is a reference diagram illustrating a vibration mode of a subframe;

4 is an exploded perspective view of a vehicle subframe according to the present invention;

5 is a table showing the results of the room noise test between the conventional subframe and the subframe of the present invention.

※ Explanation of symbols about main part of drawing ※

1: engine 2: powertrain

10: conventional subframe 20: subframe of the present invention

21 Flange 22 Engine mounting bush

30: dynamic damper 31: vibration absorbing member

32: engine mounting bush b: bolt

In order to achieve the above object, the present invention provides a vehicle subframe in which an engine and a power train are mounted so that vibration generated from the engine and the power train is transmitted to the vehicle body as it is, wherein the subframe is in one direction. The open "c" shape is formed, and both ends of the opening of the subframe are provided with a dynamic damper via a shock absorbing member so that an engine and a power train are supported on one side of the subframe and one side of the dynamic damper. It is a vehicle subframe characterized in that.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, technical features of the present invention will be described in detail with reference to the accompanying drawings.

4 is an exploded perspective view of a vehicle subframe according to the present invention, Figure 5 is a diagram showing the results of the room noise test between the conventional subframe and the subframe of the present invention.

Referring to FIG. 4, the subframe 20 according to the present invention is a “c” shaped rigid body in which one direction is opened, and is disposed at both ends of the open portions facing each other. Flange 21 in which fastening hole 21a is formed is formed, respectively. In addition, a plurality of fastening holes 20a are formed in the subframe 20 so that the subframe 20 can be fixed to the vehicle body.

On the other hand, both ends of the opening of the sub-frame 20 is provided with a linear dynamic damper 30 through the vibration absorbing member 31.

That is, the vibration absorbing member 31 is installed at both ends of the dynamic damper 30 to absorb vibrations of the engine and the power train, so that the vibration absorbing member (21) of the flange fastening hole (21a) of the subframe (20). 31 is fastened through the bolt b.

Here, the vibration absorbing member 31 is a rubber bush having a cylindrical pipe member 31a embedded therein, so that the shock transmitted to the dynamic damper 30 is damped by the rubber bush 31. It is supposed to be.

In addition, the dynamic damper 30 installed on the subframe 20 via the vibration absorbing member 31 is preferably positioned at the front side or the rear side of the vehicle body. In the exemplary embodiment of the present invention, the dynamic damper 30 is provided. Is positioned toward the front of the vehicle body so that it is connected to the front side member (not shown) of the vehicle body. This is because the dynamic damper 30 must be positioned toward the front or rear of the vehicle body to effectively absorb the bounce vibration and the pitching vibration of the subframe 20.

In addition, engine mounting bushes 22 and 32 for supporting the engine and the power train are provided at one side of the upper side of the dynamic damper 30 and one side of the subframe 20 at a position parallel to the dynamic damper 30. When the engine or the like is installed by the engine mounting bushes 22 and 32, vibration of the engine or the like is primarily absorbed.

The operation of the present invention having the above configuration is as follows.

Through the engine mounting bushes 22 and 32, the engine and the power train are advantageously supported on the upper one side of the dynamic damper 30 and the upper one side of the corresponding “c” shaped subframe 20, respectively. Of course, the subframe 20 is fixed to the vehicle body.

Here, vibrations in the engine are primarily attenuated by the engine mounting bushes 22 and 32, and the residual vibration energy is excited by the dynamic damper 30 including the subframe 20.

However, the dynamic damper 30 is installed in the subframe 20 so that the vibration damping member 31 can be damped, and the vibration entry path from the engine or the like is provided in the subframe 20 and the dynamic damper 30. Since the remaining vibration energy is respectively absorbed by the vibration absorbing member 31.

That is, as described in the prior art, the bounce mode and the pitching mode, which are the sources of generating the indoor bouncing noise, are absorbed by the vibration absorbing member 31.

Therefore, since the dynamic damper 30 having the vibration absorbing member 31 is installed in the subframe 20, the natural frequency of the subframe 20 itself is controlled, and eventually, the vibration having a large amplitude is prevented from being transmitted to the vehicle body. do.

This has the effect of preventing the natural sound pressure frequency in the vehicle room from resonating with the frequency of the subframe 20 to increase the amplitude of the noise.

In fact, as shown in FIG. 5, when the subframe according to the present invention is applied at 1500 to 2100 rpm, which is a general engine use zone, indoor noise is reduced by 5 to 10 db than when the conventional subframe is applied.

As described above, according to the automotive subframe according to the present invention, the subframe is formed into a "c" shape and a dynamic damper for absorbing vibrations is installed therein, which is one type of natural vibration of the subframe. By mainly controlling the noise, the sound pressure frequency in the vehicle is prevented from resonating, thereby significantly reducing the interior noise of the vehicle.

Claims (3)

In a vehicle subframe for mounting the engine and the power train to prevent the vibration generated from the engine and power train to be transmitted directly to the vehicle body, The subframe 20 is formed in a "c" shape with one direction open, and a dynamic damper 30 is installed at both ends of the opening of the subframe 20 via a vibration absorbing member 31. An engine and a power train are supported on one side of the subframe and one side of the dynamic damper. The vehicle subframe according to claim 1, wherein the dynamic damper (30) is disposed toward the front or the rear of the vehicle body so as to absorb the bouncing vibration and the pitching vibration of the subframe. The method of claim 1, wherein the flanges 21 having fastening holes 21a are formed at both ends of the open portions of the subframe 20 facing each other, and the vibrations are fastened to the fastening holes 21a of the flanges. Sub-frame for automobile, characterized in that the absorbing member 31 is installed through the bolt (b).