JPH03279610A - Supporting structure of piping - Google Patents

Abstract

PURPOSE:To reduce vibration transmitted from piping such as an exhaust pipe and so on to a car body by supporting the piping arranged along the front and rear directions of the car body with a power plant. CONSTITUTION:A power plant 1 is constituted by fixing and connecting a cylinder block of an engine 2, a housing of a transmission 3, a torque tube 4 and a housing of a differential unit 5, and is supported by a car body through a vibration isolation member 12. Here, an exhaust pipe 6 arranged along the front and rear directions of the car body is supported by the power plant 1 with a clamping fitting 13. In this way, as the natural frequency of the power plant 1 is lower than the frequency to generate a noise in a car, the vibration transmitted from the exhaust pipe 6 to the car body can be effectively reduced. Thus, the silence in the car can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a structure for reducing vibrations of a vehicle body by reducing vibrations of pipes arranged in the longitudinal direction of a vehicle body, such as exhaust pipes and hydraulic pipes. .

[Conventional technology]

As a conventional support structure for piping, for example,
There was a structure disclosed in Japanese Patent No. 18216.

That is, this structure connects the vehicle body and the exhaust pipe, which is the end of the piping, using a fastening fitting with a rubber bushing interposed therebetween, and the rubber bushing absorbs some of the vibrations transmitted from the exhaust pipe to the vehicle body. By absorbing it, it reduces the vibrations of the vehicle body.

[Problem to be solved by the invention]

However, in such a conventional piping support structure, although the rubber bush absorbs vibrations, as long as the vibrating piping is directly supported by the vehicle body, vibrations transmitted to the vehicle body are still considerable.

On the other hand, vibrations can be reduced by reducing the spring constant of the rubber bushings, but this method has its limitations because the exhaust pipe must be reliably supported on the vehicle body.

Therefore, the vibration of the exhaust pipe is transmitted to the car body, especially when the
The problem of generating in-vehicle noise on the order of 400)-rz remains unsolved.

Therefore, this invention has been made with these points in mind, and proposes a pipe support structure that effectively reduces vibrations transmitted to the vehicle body from pipes such as exhaust pipes, and reduces noise inside the vehicle. The purpose is to

[Means to solve the problem]

This invention provides piping arranged along the longitudinal direction of the vehicle body in a power plant that is formed by fixedly connecting an engine cylinder block, a transmission housing, a torque tube, and a differential unit housing and is supported by the vehicle body. We have proposed a support structure for piping that supports the above problems.

[Function] When the piping vibrates, this vibration is first transmitted to the vehicle body via the power plant, where a vibration transmission system is established in which the piping is the vibration source, the power plant is the vibration transmission medium, and the vehicle body is the vibration input target. is formed.

At this time, the vibration transmissibility β at which the power plant transmits vibrations from the piping to the vehicle body is determined as follows from the natural frequency p of the power plant and the excitation frequency ω of the vibration input thereto.

The power plant consists of the engine cylinder block, transmission housing, torque tube,
Since the housing of the differential unit is rigidly connected, they together have a natural frequency P of about 101(z).

On the other hand, the excitation frequency ω that causes noise inside the car is 30 to 400.
Hz, and the natural frequency p of the power plant is
high compared to Therefore, in this state, the denominator in the above equation increases and the value of the vibration transmissibility β decreases, so the vibrations generated by the piping are attenuated as they pass through the power plant, and are thereby transmitted to the vehicle body. Vibrations are greatly reduced.

(Example) The structure of the first embodiment, which embodies the structure of this invention, is
This will be explained based on the diagram. In this embodiment, an exhaust pipe of piping is connected to a power plant.

FIG. 1 shows a side view of the piping support structure of this embodiment.

As shown in the figure, the piping support structure of this embodiment includes a power plant 1 and an exhaust pipe 6 arranged in the longitudinal direction of the vehicle body. The power plant 1 has an engine 2 and a transmission 3 arranged at the front of the vehicle body, and a differential unit 5 arranged at the rear of the vehicle body. Then, after fixing the cylinder block of the engine 2 and the housing of the transmission 3 together, these and the housing of the differential unit 5 are further rigidly connected with a torque tube 4 with a propulsion shaft inserted inside, so that the entire structure is completed. It is a single rigid body. Further, the second exhaust pipe 6 is connected to an exhaust manifold 7 which collects exhaust from each exhaust pipe of the engine 2, and an exhaust vibrator 8 is connected to the exhaust manifold 7.
A catalyst unit 9 is connected to the exhaust vibrator 8 from the front side of the vehicle. A pre-muffler 10 and a main muffler 11 are respectively arranged.

This power plant 1 is supported by the vehicle body at each position of the engine 2 and the differential unit 5 via vibration isolating members 12 such as insulators.

On the other hand, in the exhaust pipe 6, the front exhaust manifold 7 is fixed to the engine 2, and the exhaust vibe 8 is also fixed to the fastening metal fitting 1.
3 is fixed to the power plant 1 at multiple locations. That is, while the exhaust pipe 6 is fixed integrally with the power plant 1, it has a structure that does not contact the vehicle body at all.

In addition, since the rear part of the exhaust pipe 6 protrudes rearward from the position where the differential unit 5 is arranged, the stay 14 is fixed to the differential unit 5 at the same part, and the stay 14 and the exhaust pipe 6 are connected with the fastening metal fitting 13. ing.

An example of a mounting structure using the fastening metal fittings 13 will be explained in FIG. 2. This figure is a sectional view taken along the line ■-■ in FIG. 1.

As shown in the figure, the fastening metal fittings 13 are connected to the power plant 1.
A plant-side locking piece 14 fixed to the torque tube 4 by, for example, welding, and a pre-muffler 10 of the exhaust pipe 6.
It is constructed by fastening an exhaust pipe side locking piece 15, which is also fixed by welding, via an insulator 17 made of rubber. Then, the vibration transmitted from the exhaust pipe 6 to the fastening metal fitting 13 is transmitted to the power plant 1 after being caused to oscillate by the elasticity of the insulator 17.

Next, the operation of the pipe support structure of this embodiment will be explained.

As the engine 2 operates, the exhaust pipe 6 resonates and vibrates due to vibrations from the engine 2 and ventilation within the exhaust pipe 6. Then, the vibration of the exhaust pipe 6 is first transmitted to the power plant 1, and then this vibration is further transmitted to the vehicle body. A vibration transmission system is formed in which the vehicle body is the transmission medium and the vehicle body is the vibration input target.

Generally, the vibration transmissibility β of a vibration transmission system is determined as follows from the excitation frequency ω input to the transmission system and the natural vibration P of the vibration transmission medium.

Here, the frequency of vibration that generates in-vehicle noise is 30 to 400. On the other hand, the entire power plant 1, which is a vibration transmission medium, is a rigid body, and its natural frequency is generally 10H.
It will be about z. Therefore, from these conditions, the excitation frequency ω in the above equation is 30 to 4001 (z, and the natural frequency p is 1
When substituting 0Hz into the above equation, the vibration transmissibility β is 0.1
25 to 0.0006 (-18 dB to -64 dB).

That is, it can be seen that in the same vibration transmission system, the vibrations that are transmitted to the vehicle body and that generate in-vehicle noise are significantly reduced compared to the case where the same vibrations are directly input to the vehicle body.

Further, since the same vibration is transmitted through the fastening metal fitting 13 and the vibration isolating member 12, it is clear that the vibration transmitted to the vehicle body is further reduced.

Therefore, depending on the pipe support structure of this embodiment, the exhaust pipe 6
Vibrations transmitted from the vehicle to the vehicle body 1, particularly vibrations in frequency bands that generate interior noise, can be significantly reduced, and the quietness inside the vehicle can be improved.

Further, since the exhaust pipe 6 is not fixed to the vehicle body, the power plant 1 and the exhaust pipe 6 are displaced together when there is a large displacement such as engine roll when starting the engine. Conventionally, the exhaust pipe 6 has been fixed to the vehicle body, and since a large load is applied to this part, an expensive flexible tube has been used, but in the pipe support structure of this embodiment, the connection between the two This eliminates the need for excessive force to be applied to the exhaust manifold 7, which is the main part of the exhaust pipe 6, and thereby has the effect of improving the durability of the exhaust pipe 6 without requiring a special structure.

Next, a second embodiment of the present invention will be described based on FIG. In this embodiment, a cooling pipe is fixed to a power plant as a pipe.

As shown in the figure, in the vehicle of this embodiment, the engine 2 is located at the rear of the vehicle, and the radiator 18 is located at the front of the vehicle, and the two are connected by two cooling pipes 17 that circulate coolant. ing. The cooling pipe 17 is elastically supported by the torque tube 4 of the power plant 1 via a fastening fitting 13.

The cooling piping 17 generates pulsations and vibrations due to the rotation of the blades of a water pump (not shown).

If the number of the pump blades is 8, the pulley ratio between the pump and the crankshaft is 1.3, and the engine rotation speed is 800 to 5000 rpm, then this cooling pipe 17
The frequency of vibration is 107 to 667Hz. Then, by substituting these frequencies into the above equation as the excitation frequency ω, the vibration transmissibility β is 0.0008 to 0. OOO2 degree (-4・
1 to -73 dB), indicating that the vibrations transmitted to the vehicle body side are significantly reduced.

The other structures and operations are the same as those in the first embodiment, so their explanations will be omitted.

Furthermore, a third embodiment of the present invention will be described based on FIG. In this embodiment, hydraulic piping for a four-wheel steering mechanism is fixed to a power plant as piping.

As shown in the figure, the hydraulic piping 19 of the four-wheel steering mechanism connects a hydraulic pump 20 located at the front of the vehicle and a power cylinder 21 located at the rear of the vehicle for steering the rear wheels. There is a solenoid valve 2 that controls the hydraulic pressure.
2 is placed.

When the solenoid valve 22 operates and the oil pressure fluctuates transiently, a so-called oil hammer phenomenon occurs, and vibrations of about 100 Hz occur in the hydraulic piping 19. In addition,
This solenoid valve 22 is dithered at about 100 Hz to prevent hysteresis in its operation, so that the oil flows smoothly, but this vibration also affects the hydraulic piping 19.
is transmitted to. Therefore, if these 100 Hz frequencies are substituted into the above equation as the excitation frequency ω, the vibration transmissibility β becomes 0.001 (-39.9 dB), which means that the vibrations transmitted to the car body can be greatly reduced. Recognize.

The other structures and functions are the same as those in the first embodiment, so their explanation will be omitted.

In each of the above embodiments, the exhaust pipe 6, the cooling pipe 17, and the hydraulic pipe 19 are individually fixed to the power plant 1, but two or all of them may be fixed at the same time. Moreover, although these three examples are given as piping in the above-mentioned Example, it goes without saying that piping is not limited to these.

〔Effect of the invention〕

As explained above, depending on the piping support structure of the present invention, the natural frequency of the power plant is lower than the frequency that generates interior noise, so vibrations are transmitted to the vehicle body from piping such as the exhaust pipe. can be effectively reduced, thereby improving the quietness inside the vehicle.

[Brief explanation of the drawings] Figure 1 is a side view of the piping support structure of the first embodiment, Figure 2 is an enlarged sectional view taken along the m-tt line in Figure 1, and Figure 3 is the piping of the second embodiment. A side view of the support structure. FIG. 4 is a side view of the piping support structure of the third embodiment.

Claims (1)

[Claims] (1) The power plant, which is formed by fixedly connecting the engine cylinder block, transmission housing, torque tube, and differential unit housing, and is supported by the vehicle body, has piping arranged along the longitudinal direction of the vehicle body. A support structure for piping characterized by supporting it.