JPH01220738A - Vibration isolator encapsulating variable viscosity fluid - Google Patents

Abstract

PURPOSE:To perform fine control and to reduce vibration transmitting force considerably by setting the control level for switching damping for every peak of vibration acceleration of a supporting member through a control level setting means thereby controlling the voltage to be applied onto an electrode orifice. CONSTITUTION:A control level setting means (h) sets the control level for switching damping randomly for every peak of vibration corresponding to the magnitude of vibration acceleration of a supporting member (b) detected through an acceleration sensor (g). Voltage to be applied onto an electrode orifice (e) constituting a CR system between an exciting body (a) and the supporting body (b) is controlled based on the control level set through the control level setting means (h) thus varying the viscosity of electrical rheology fluid communicating between a main fluid chamber (d) and a sub-fluid chamber (f) having variable volume. By such arrangement, fine control is made for each vibration peak even when the supporting member exhibits a complex vibration mode, resulting in considerable reduction of the entire vibration transmitting force.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is characterized in that an electrorheological fluid whose viscosity changes depending on an applied voltage is sealed between a main fluid chamber and a sub-fluid chamber. The present invention relates to a variable viscosity fluid-filled vibration isolator that can control the viscosity of a fluid within an orifice.

2. Description of the Related Art As this type of variable viscosity fluid-filled vibration isolator, for example, one disclosed in Japanese Patent Laid-Open No. 104828/1982 is known, in which an electrorheological fluid is sealed in a pair of fluid chambers. By changing the viscosity of the fluid within the orifice, the flow conditions within the orifice are changed and the damping frequency range can be adjusted.

Therefore, in such a variable viscosity fluid-filled vibration isolator,
To adjust the damping frequency range, it is sufficient to simply change the electric power applied to the electrorheological fluid within the orifice, thereby significantly simplifying the configuration.

Problems to be Solved by the Invention However, in such a conventional vibration isolator filled with a variable viscosity fluid, the vibrations transmitted through the vibration isolator are caused by human force from the supporting elastic body and the fluid space through the orifice. Since the phase with the input from the expansion elasticity when the fluid is moved through the orifice changes from 06 to 1801 due to the dynamic damper action using the fluid in the orifice as a mass, the vibration isolator is simply vibrated in a one-degree-of-freedom system. Even if controlled as a model, it is not possible to sufficiently reduce the vibration transmission force.

In particular, when the variable viscosity fluid-filled vibration isolator is applied to an automobile engine mount, the power unit supported by multiple engine mounts generates complex vibrations.
There is a problem in that it becomes difficult to expect further reduction in the vibration transmission force.

Therefore, the present invention predicts the vibrations on the side where vibrations are input through the vibration isolator and controls the damping rate in the orifice for each vibration. An object of the present invention is to provide a variable fluid-filled vibration isolator.

Means for Solving the Problems In order to achieve the above objects, the present invention, as shown in FIG. , a main fluid chamber (d) arranged in parallel with the elastic body (c) and whose volume changes due to input vibration, and a sub-body whose volume is variable and communicates with the main fluid chamber (d) via an electrode orifice (e). chamber (f), and these main and auxiliary fluid chambers (
d).

(f) is filled with an electrorheological fluid whose viscosity changes according to the applied voltage, and whose attenuation rate inside the orifice changes according to the voltage applied to the electrode orifice (e). In the vibrator, an acceleration sensor (g) that detects the vibration acceleration applied to the support (b), and an arbitrary signal for each peak depending on the magnitude of the input signal obtained by the acceleration sensor (g) are provided. and a control level setting means (h) for setting a control level for attenuation switching, and a voltage applied to the electrode orifice (e) according to the attenuation switching control level obtained by the control level setting means (h). It is configured by controlling the

Effect With the structure described above, in the variable viscosity fluid-filled vibration isolator of the present invention, the support body (b) detected by the acceleration sensor (g)
), the control level setting means (h) arbitrarily sets a damping switching control level for each vibration peak, and the applied voltage is controlled based on this. Even when the vibration mode exhibits a complex vibration mode, fine control along each vibration peak value is possible, so the overall vibration transmission force is significantly reduced.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment of the variable viscosity fluid-filled vibration isolator of the present invention, and an example in which the variable viscosity fluid-filled vibration isolator is used as an engine mount 10 of an automobile will be described below.

That is, the engine mount 10 is an engine.

A first frame body 14 is attached via bolts 12 to the power unit M side as a support body which is a combination of a transmission, etc., and a bolt 16 is attached to the vehicle body B side as an excitation body.
The second frame body 18 is attached via the first frame body 18, and the second frame body 18 is attached via the first frame body 18.
It includes a hollow rubber insulator 20 as an elastic body fixed liquid-tightly between the second frames 14 and 18.

The inside of the hollow part 22 of the rubber insulator 20 is separated by a partition plate 24 having an inverted trapezoidal cross section and fixed to the first frame 14 side. spaced apart in the opposite direction of the second frame 14.18;
The second frame 18 side separated by the partition plate 24 (lower side in the figure)
The chamber is defined as the main fluid chamber 26.

On the other hand, the partition plate 24 is on the first frame 14 side (upper part in the figure).
The end face is closed with a diaphragm 28, and these partition plates 24
A chamber between the diaphragm 28 and the diaphragm 28 is a sub-fluid chamber 30.

The outside of the diaphragm 28 is covered by the first frame 1'4, and the diaphragm 28 and the first frame 14
An air chamber 32 is formed between them.

An electrorheological fluid whose viscosity changes depending on the applied voltage is sealed in the main fluid chamber 26 and the sub-fluid chamber 30, and the main and sub-fluid chambers 26 and 30 are separated by the partition! 24 through an electrode orifice 34 formed in the center of the electrode orifice 24.

The electrode orifice 34 is an orifice provided with electrode plates 36, 36a. One electrode plate 36 is formed in a cylindrical shape, and the other electrode plate 36a is disposed in the center thereof supported by an electrically insulating member. and these picture electrodes vi, 3
An orifice passage 34a is provided between 6.36a.

And the above pair of i! The maple tentatives 36 and 36a are connected to a power source 40 and a control unit 41 via harnesses 38 and 38a, respectively.
The first frame body 14 is provided with an acceleration sensor 42 that detects the vertical acceleration of the power unit M, and a control signal corresponding to the acceleration signal detected by the acceleration sensor 42 is output to the control section 44. be done.

Therefore, the electrode orifice 34 has a power unit M.
A control voltage is applied according to the vertical acceleration of the electrode orifice 34, and the fluid viscosity within the electrode orifice 34 is changed.

By the way, the engine mount lO with the above configuration is the third
The input vibration xl from the road surface via the vehicle body B is accompanied by vibration x1 in the support elastic spring of the rubber insulator 20 itself and vibration x3 of the movable fluid IEkm in the orifice passage 34a. Main and auxiliary fluid chambers 26.
Expansion elastic spring K of the main fluid chamber 26 side wall when the fluid is moved between 30 and 30.

is transmitted to the power unit M via.

Therefore, the total force F input to the power unit M is applied to the support elastic spring, the input F1 from and the expansion elastic spring!
Input from F! The resultant force (F = F.

expressed as 1,000 F,).

The displacement Xt+X appearing in the power unit M and the fluid in the orifice passage 34a with respect to the input excitation The relationship is shown in FIG. 4(b).

In the graphs shown in FIGS. 4(a) and (b) above, the displacement X of the power unit M is within a predetermined range (-XO to XO)
There is a range where the displacement is less than 1 ml and another range where the displacement is large.
, and tl, which corresponds to a large amount of displacement.

Incidentally, in order to reduce the vibration transmission force to the power unit M, the maximum value of the total force F may be reduced.

That is, in the period t1 in FIG. 4, since the absolute value 1x,1 of the displacement of the power unit M is large, the total force I
P+ also increases, and when the IFI is large, F,,F
, are each in phase and have large absolute values.

Further, in the above period 1+, since IF, 1 is ahead in phase compared to IF l, the total force IFI is in the direction of decreasing.

Therefore, in order to avoid an increase in the total force IFI (lower F wax) during this period t1, it is necessary to decrease IP,1.

Here, from the model in Fig. 3, when the power unit M is almost stationary (c+i,+ is small), in order for the spring to quickly return to the equilibrium state from the deflected state and reduce IF,1, , the fluid quality I1 is reduced by decreasing the damping factor C.
It is desirable not to restrict the movement of m.

Therefore, during the period t, the damping coefficient G may be controlled to be lowered.

On the other hand, during the period tt, the force IFI applied to the power unit M
is relatively small, and the value of F has little influence on the acceleration of the power unit M.

Therefore, during the period jy, the damping coefficient C is lowered to increase the energy loss in the entire resonant system, thereby reducing the kinetic energy of the power unit M.
(Is it possible to lower max?) In this way, depending on the absolute value of the displacement of x, the damping coefficient C
(see Fig. 5), the damping force can be used more effectively to lower Xta+ax. In this example, the damping coefficient C is lowered in the period 1+, and the damping coefficient C is lowered in the period t. make it higher.

Therefore, during the period t when the displacement (acceleration) of the power unit M is relatively large, the damping force is small.

The state change rate of is large, the rise of IF tl becomes fast, IFIII lax becomes small, and period t.

In this case, the damping force is large, and the vibration energy of the resonant system is consumed.

By the way, in reality, the state change is controlled in the same way by measuring the acceleration with a phase shift of -1800, but
The vibration acceleration level is not constant as shown in FIG.

Therefore, it may be possible to improve the effect to some extent even if the acceleration to be switched is kept constant, or it is more effective to set a corresponding control level for attenuation switching for each peak of each waveform.

To do this, as shown in FIG. 6, the peak of the acceleration waveform can be predicted at each zero cross (indicated by * in the figure), and the switching acceleration g1 can be set as the attenuation switching control level based on that value.

The above switching acceleration gn is the differential value g (tn) of the acceleration at the zero-crossing point and the second-order differential value "(
, , ), and can be expressed as □ by the following formula.

g-=AX1g(kn)+B-g(tnl+c++
++++■ However, A, B, and C are positive constants.

In other words, as shown in Figure 7, the above equation 0 has the slope y (tn) at the zero cross and the rate of change in slope "y" (tn).
This was derived by noting that if the positive and negative values of , are the same, the immediately following peak level will be high, and if the positive and negative values are opposite, the peak level will be low.

FIG. 8 shows an anagorhythm for controlling the voltage applied to the electrode orifice 34 based on the switching acceleration g1. First, in step l, the vertical acceleration g (tn) applied to the power unit M by the acceleration sensor 42 is
is detected, and in step 2, the absolute value Ig (tnl) is converted, and in step 2, the width Δg is considered to ensure g(tn,.) and (g(tn)=<6g) is determined. .

If YES in step ■, g (t
While determining n), the g (tn) is further passed through the differentiator ■ to determine "g" (tn), and from these g (tn) and g (tn), in step ■ as a control level setting means, the above Switching acceleration g+=A based on formula 0
x l g (tn) + B-"g" (tn) l
Find +C.

Then, compare g+ obtained in the above step (■) and Ig(tnl obtained in the above step
g (tn)l> g +)L, if YES, x-y
- The voltage applied to the electrode orifice 34 is turned off by the knob (2), while if NO, the voltage is turned on by the step (2).

In addition, if it is determined NO in the above step ■, step X sets (g r = g t) and the above step
Proceed to.

Therefore, by turning off the voltage in step (3) above, the electrorheological fluid in the electrode orifice 34 becomes in a state where the viscosity is reduced, the damping coefficient C° becomes small, and the spring quickly returns to an equilibrium state. It is possible to reduce the total force F by reducing lF and l.

On the other hand, by turning on the voltage in step (2), the viscosity of the fluid in the electrode orifice 34 is increased, the damping coefficient C becomes large, and vibration energy can be absorbed.

In this way, in the control of changing damping according to acceleration, the switching acceleration g7 is calculated by anticipating the next acceleration peak level at the time when the acceleration waveform zero-crosses, and voltage control is performed based on this switching acceleration g7. , to effectively reduce the vibration transmission forceb(
can.

That is, as shown in the characteristic in FIG. 9, X, max/x
The vibration transmission force expressed by the amount AX has another characteristic A that passes through two fixed points P and Q when the damping coefficient is constant.

It can be significantly reduced compared to B and C.

In this example, a case where the variable viscosity fluid-filled vibration isolator of the present invention is used in an automobile engine mount lO is shown, but the present invention is not limited to this and can be applied to general vibration isolators. Needless to say.

As described in detail of the invention, in the variable viscosity fluid-filled vibration isolator of the present invention, the control level for damping switching is set for each peak of the vibration acceleration of the support using the control level setting means, Since the voltage applied to the electrode orifice is controlled based on the control level, fine control of each peak is possible even for input vibrations in complex modes, and vibration transmission force can be significantly reduced. It has this excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the concept of the present invention, Fig. 2 is a sectional view showing an embodiment of the invention, Fig. 3 is a mechanical model diagram of the invention, and Fig. 4 is a valley vibration waveform of the vibration transmission system. , and the same figure (2L
) is the displacement characteristic diagram, the same figure ('b) is the transmission force characteristic diagram, and the fifth
The figure is an explanatory diagram showing the relationship between the displacement of the support and the damping rate.
The figure is a characteristic diagram of the level of vibration acceleration applied to the support, Figure 7 is an explanatory diagram showing the relationship between the slope at the zero cross point and the rate of change of the slope when setting the switching acceleration, and Figure 8 is the invention of the present invention. FIG. 9 is an explanatory diagram showing one embodiment of an anagolithm for controlling the vibration transmission rate. FIG. lO...Engine mount (viscosity variable fluid-filled vibration isolator), 20...Rubber insulator (elastic body), 2
4... Split plate, 26... Main fluid chamber, 28... Diaphragm, 30... Sub-fluid chamber, 34... Electrode orifice, 36.36a... Electrode plate, 40... power supply, 4
DESCRIPTION OF SYMBOLS 1... Control part, 42... Acceleration sensor, B... Vehicle body (vibration body), M... Power unit (support body). 2 people Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 @ Figure 9

Claims (1)

[Claims] (1) An elastic body disposed between the vibrating body and the support body, a main fluid chamber disposed in parallel with the elastic body whose volume changes due to input vibration, and communicating with the main fluid chamber via an electrode orifice. The main and sub-fluid chambers are filled with an electrorheological fluid whose viscosity changes according to the applied voltage, and the attenuation rate in the orifice is controlled by the voltage applied to the electrode orifice. In a variable viscosity fluid-filled vibration isolator in which the A control level setting means for arbitrarily setting a control level for attenuation switching is provided, and the voltage applied to the electrode orifice is controlled in accordance with the attenuation switching control level obtained by the control level setting means. Vibration isolator filled with variable viscosity fluid.