JPH04191541A - Vibration proof support means - Google Patents

Abstract

PURPOSE:To cope with changes in the position of a center of gravity of a structure by disposing in series between a structure and a support body an elastic body and a displacement providing means for providing the elastic body with displacement in the direction same as that of the deformation of the elastic body. CONSTITUTION:An elastic body 15 and a liquid chamber 17 are provided between an engine 11 (structure) and a body side member 12 (support body). The lower cylindrical part 14a of a support member 14 is capable of displacement relative to an attachment member 16. The liquid chamber 17 is connected through a pipe 19 to a cylinder. The piston in the cylinder is in contact with a cam attached at a certain phase angle to an engine cam shaft. The cam has four teeth to change the volume of the liquid chamber 17 when the engine is driven to give displacement to the elastic body 15 with a frequency of 2omega. As a result, vibration of a support side is attenuated by absorbing the periodical changes in the position of a center of gravity of the structure by means of the elastic body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a vibration-proof support device for supporting a structure whose center of gravity periodically fluctuates, such as an automobile engine.

[Conventional technology]

An example of a conventional anti-vibration support device is the one shown in FIG.

This is a device that elastically supports a structure 4 whose center of gravity changes periodically by an elastic body l sandwiched between mounting jigs 2 and 3, and the mounting jig 2 is attached to the structure 4. fixed,
A mounting jig 3 is fixed to a support base 5.

FIG. 6 is a diagram showing the configuration of FIG. 5 as a model, where the mass of the structure 4 is m, the spring stiffness of the elastic body 1 is k, and the elastic body l
Let C be the attenuation constant of .

Then, the variation r of the center of gravity inside the structure 4 is expressed as r=r,
When exp(jωt) +r2exp(j2ωt), the equation of motion □ regarding the displacement X of the structure 4 becomes as shown in equation (1) below.

d 2 fx+r+exp(jωt)+r2exp(j
2ωt)1 Note that J is an imaginary unit (j2--1).

Here, when m m is assumed, the displacement X of the structure 4 is expressed by the following equation (2).

・・・・・・(2) Then, if the usage area of this spring-mass system is ω)ω1°, then X= ~fr+exp(jωt) +r2exp(j
2ωt) ) Therefore, the excitation force F of this system to the support base 5 is expressed as in the following equation (3).

F=(k+Jωc)x=(k+jωc)(r+exp(jωt)+r2ex
p(j2ωt))...(3) [Problem to be solved by the invention] As described above, in the conventional anti-vibration support device shown in FIG. 5 and the relative displacement between elastic body 1
Since the structure was such that the dynamic force is multiplied by the spring stiffness or is applied as the excitation force F to the support base 5, it is necessary to increase the elements that constitute the dynamic spring stiffness, that is, the damping constant C and the spring stiffness 1 ( If a vibration occurs, the excitation force F applied to the support base 5 will increase in proportion to the norm of the spring stiffness, forming a new vibration system and increasing the vibration on the support base 5 side. There are issues to be solved.

This invention was made by focusing on the unresolved problems that conventional vibration isolators have, and has developed an anti-vibration device that can effectively block the vibrations of a structure whose center of gravity periodically fluctuates. The purpose is to provide a swing support device.

[Means to solve the problem]

In order to achieve the above object, the invention according to claim (1) provides a vibration-proof support device for a structure whose center of gravity changes periodically, wherein an elastic A body and a displacement imparting means for applying displacement fluctuation in the same direction as the deformation direction of the elastic body to the elastic body at a cycle that is an integral multiple of the fluctuation cycle of the structure are interposed in series.

Further, in order to achieve the above object, the invention according to claim (2) provides a vibration-proof support device for a structure whose center of gravity changes periodically, the structure being provided between the structure and the supporting side. An elastic body is interposed, and a fluid chamber that can expand and contract in the same direction as the deformation direction of the elastic body is interposed between the support side and the elastic body, and a period that is an integral multiple of the fluctuation period of the structure. A fluid flow means for moving fluid in and out of the fluid chamber is provided.

[Effect]

When the structure vibrates, does the distance between the structure and the supporting side change?In the invention set forth in claim (1), the displacement of the elastic body is varied by the displacement applying means, and the distance between the structure and the support side changes. )
In the described invention, the elastic body changes its displacement as the fluid chamber expands and contracts as the fluid is taken in and out by the fluid flow means, so the vibration of the structure is caused not by the elastic deformation of the elastic body but by the displacement of the elastic body. Therefore, even if the damping constant and spring constant of the elastic body are increased, a new vibration system will not be formed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams showing a first embodiment of the present invention, in which the present invention is applied to a device for supporting a vehicle engine on a vehicle body.

First, to explain the configuration, as shown in FIG. and an elastic body 15 sandwiched between the support jig 14,
Liquid chamber 1 formed between support jig 14 and mounting jig 16
7.

A cylindrical portion 14a that is open at the bottom is formed at the lower part of the support jig 14, and the mounting jig 16 is loosely inserted into the inside of this cylindrical portion 14a. Therefore, relative displacement in the vertical direction is possible between the support jig 14 and the mounting jig 16.

An internal hollow elastic body 18 is fixed to the inner surface of the cylindrical portion 14a and the upper surface of the mounting jig 16, and the cavity of the elastic body 18 forms the liquid chamber 17. In addition, liquid chamber 1
A liquid is sealed inside 7.

Therefore, the static load of the engine 11 is
6 and the support jig 14, the static rigidity of the elastic body 15,
It is supported by the static internal pressure of the liquid sealed in the liquid chamber 17.

Furthermore, the liquid chamber 17 communicates through a liquid pipe 19 into a cylinder 22 that is fixed to the lower part of the engine block 21 and opens upward, as shown in FIG.

Note that liquid is also sealed in the liquid pipe 19 and the cylinder 22, similarly to the liquid chamber 17.

A piston 23 is inserted into the cylinder 22 so as to be able to move forward and backward, and the upper surface of the upper end 23a of the piston 23 is in contact with a cam 25 provided on the engine camshaft 24 above the engine block 21. .

Note that the upper end 2 of the engine block 21 and the piston 23
A coil spring 26 that urges the piston 23 upward is interposed between the piston 23 and the piston 3a.

Here, the cam 25 is attached to the engine camshaft 24 (rotational speed ω/2) with a phase angle φ, and has four teeth. In addition, the short axis of the cam 25 is a1, the long axis is b
It is said that

Next, the operation of this embodiment will be explained.

FIG. 3 is a diagram showing a model of the configuration of this embodiment,
First, I will give a theoretical explanation.

That is, the difference from the conventional configuration explained in FIG. 6 is that only a new system is added between the elastic body 15 and the vehicle body side member 12 to provide only displacement fluctuations.

If the equation of motion is determined by setting the displacement of this system as δ, it will be as shown in equation (4) below.

Here, it is assumed that the displacement δ of the system is the rotational frequency ω of the crankshaft (not shown) of the engine 11 (the rotational speed of the engine camshaft 24 is ω/2, and that the engine is a 4-cycle engine). The two components are changed by 2ω. In other words, δ=δ. Let exp(j 2ωt) be. At this time, the displacement X of the engine 11 is as follows (5
) is as follows.

X (r2(2ω)2+2jζωacknowledgedωδ.tenω,,'
δol exp(j2ωt)...(5) And ω)ω.

In the usage area of x= −(r+exp(jωt) +r2exp(j
2(L) t) ), which is exactly the same as in the case of the conventional vibration isolating support device.

However, the excitation force F on the vehicle body side member 12 is F =
(k+ jωc) (x-δ) = (k+jωC) X (r+exp(jωt)+(r2+δo)exp(
j2ωt)1. In other words, if the condition δo''rz is satisfied, the excitation force F of the frequency 2ω component will not be transmitted to the vehicle body side member 12.

Furthermore, considering the same way, δ= −(r+exp(jωt) +r2exp(j
2ω1)), the excitation force F is not transmitted to the vehicle body side member 12 at all.

Since the excitation force exerted on the entire system by the periodic displacement fluctuation due to the system is zero, the work done by this displacement fluctuation on the entire system is zero. Therefore, theoretically, the energy consumed by the newly added system is zero.

Next, the specific operation of this embodiment will be explained.

When the engine 11 is driven, the engine camshaft 24
rotates, and the cam 25 rotates at a rotation speed of ω/2 with a delay of phase φ from that rotation.

Then, the screws 1 to 23 move up and down due to the downward biasing force of the cam 25 and the upward biasing force of the coil spring 26. (The number of rotations of the cam 25 is 6
The liquid moves back and forth using the J/2X cam 25 with 4 teeth.

Therefore, since the volume of the liquid chamber 17 changes at a frequency of 2ω, a displacement fluctuation is applied to the elastic body I5 in the same direction as its elastic deformation and at a frequency of 2ω. In other words, the model shown in FIG. 3 is realized.

If the effective area of the piston 23 is A, and the effective area that pushes the elastic body 18 or the mounting jig 16 is A', then if the relationship =-r2cos2ωt is satisfied, the rotational secondary excitation force of the engine 11 is , are canceled out by the displacement fluctuation of the elastic body 15, and are not transmitted to the vehicle body side member 12.

Furthermore, the energy consumed in this example is
2 and piston 23.

In other words, with the configuration of this embodiment, it is possible to prevent the transmission of the excitation force F to the vehicle body side member 12 without requiring a large amount of energy compared to the conventional configuration, and to create a new vibration system. As a result, the vibration of the vehicle body side member 12 is reduced.

Here, in this embodiment, the liquid chamber 17 corresponds to the displacement applying means of the invention described in claim 11, and the liquid pipe 19. cylinder 22. screw 1 hem 23. cam 25 and coil spring 26 correspond to 2) The liquid flow means of the described invention is constructed.

FIG. 4 is a diagram showing a second embodiment of the present invention, and corresponds to FIG. 1 of the first embodiment described in section 1. Other configurations are the first
This is similar to the example.

That is, in this embodiment, the mounting jig 16 is formed with a cylindrical portion 16a that enters the cylindrical portion 14a of the support member 14, and a screw is provided on the outer circumferential portion of the cylindrical portion 16a that slides into contact with the inner circumferential surface of the cylindrical portion 14a. 1 to 27a and 27b are provided.

In the first embodiment, the expansion and contraction of the liquid chamber 17 was realized by elastic deformation of the elastic body 18, so energy was wasted. Since it only needs to slide, energy consumption can be further reduced.

The effect of the pond is the same as that of the first embodiment.

In addition, in each of the above embodiments, the case where the anti-vibration support device according to the present invention is applied to the anti-vibration support device 10 of engine II for a vehicle is explained, or the object of application of the present invention is limited to this. It may also be a vibration isolating support device for other structures.

Further, in the above embodiment, the displacement variation is applied to the elastic body 15 by the expansion and contraction of the liquid chamber 17, but the present invention is not limited to this, and if there is a means for applying displacement variation to the elastic body 15, other means may be used. It doesn't matter if there is.

〔Effect of the invention〕

As explained above, in the inventions described in claims (1) and (2), since the vibrations of the structure are absorbed by the displacement fluctuation of the elastic body, a large amount of energy is required. Therefore, it is possible to prevent the transmission of the excitation force to the support side, and as a result, there is no need to form a new vibration system, which has the effect of reducing vibrations on the support side.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vibration isolation support device according to a first embodiment of the present invention;
FIG. 2 is a sectional view showing an example of a configuration for moving liquid in and out of a liquid chamber at a predetermined frequency, FIG. 3 is a model representation of the configuration of the first embodiment, and FIG. 4 is a second embodiment of the present invention. FIG. 5 is a sectional view of a conventional vibration isolating support device, and FIG. 6 is a model representation of the configuration of FIG. 5. 10... Anti-vibration support device, 11... Engine (structure), 12 - Vehicle body side member (support side), 15... Elastic body, 7... Liquid chamber (fluid chamber), 19 ...Liquid pipe, 22...Cylinder, 23...Piston, 2
5...Cam, 26...Coil spring

Claims (2)

[Claims] (1) An anti-vibration support device for a structure whose center of gravity changes periodically, which includes an elastic body between the structure and the supporting side, and displacement fluctuation in the same direction as the deformation direction of the elastic body. and a displacement imparting means for applying displacement to the elastic body at a cycle that is an integral multiple of a fluctuation cycle of the structure, interposed in series. (2) A vibration isolating support device for a structure whose center of gravity changes periodically, wherein an elastic body is interposed between the structure and the supporting side, and between the supporting side and the elastic body. a fluid chamber that can be expanded and contracted in the same direction as the deformation direction of the elastic body, and further,
A vibration isolating support device characterized in that a fluid flow means is provided for moving fluid into and out of the fluid chamber at a cycle that is an integral multiple of a fluctuation cycle of the structure.