JPH094662A - Vibration controller for disk brake - Google Patents

Abstract

PURPOSE: To improve the performance of a vibration controller (performance of preventing a creak) by applying surely vibration to detect brake vibration with a first piezo electric element and damp the brake vibration with a second piezo electric element without being affected by the incorporating accuracy or the like of both piezo electric elements. CONSTITUTION: A first piezo electric element 7 for vibration detecting and a second piezo electric element 8 for vibration applying are in series disposed to be pressed against a pad 3. Thus, a difference between press forces of the first and second piezo electric elements is not generated, so that the vibration is stably detected and applied. Also. the performance is not degraded by that the detection and application of the vibration is performed by one element or the detecting point and vibration applying point are located in different positions respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device for suppressing so-called squeaking of a disc brake by actively suppressing brake vibration which is a cause of squeaking.

[0002]

2. Description of the Related Art As a device for suppressing the squeal of a disc brake by an active method, for example, Japanese Patent Laid-Open No. 4-54325.
There are some which are shown in Japanese publications. This is a vibration damping device that detects a brake vibration using a piezoelectric element and vibrates a pad based on the detection signal, and attenuates the brake vibration by the vibration.

[0003]

In the conventional vibration damping device as disclosed in the above publication, two piezoelectric elements used for vibration detection and vibration are arranged in parallel and pressed against the pad. Therefore, there is a problem in that the vibration damping performance depends on the mounting accuracy of each piezoelectric element to the caliper.

That is, if one of the piezoelectric elements projects slightly more than the other element due to an error in processing or assembly, the pressing force of the two piezoelectric elements against the pad will be different, and the vibrating element will be a sufficient pad. Although it can be vibrated by being pressed, the situation that the detection piezoelectric element is not sufficiently pressed against the pad and the vibration of the pad cannot be detected correctly, or the opposite situation occurs, and the squeal suppressing effect ( Vibration damping effect) is reduced. Further, as a countermeasure against this problem, high precision assembly is required, which causes a cost increase. Further, even if the assembling accuracy is increased, the position of the element pressing surface may be displaced due to the difference in thermal expansion of the piezoelectric element assembling portion due to the influence of the temperature change, and the above-mentioned problem of performance deterioration may occur.

Further, in the vibration suppression by such a method, it is generally said that the control is more stable if the vibration detection and the vibration are performed at the same place {for example, J. of Inte
ll. Mater. Struct. , Vol. 3-Ja
Nuary 1992 (1992 Technology)
Publishing Co. , Inc) P167
However, for this reason, as shown in FIG. 3 of the above-mentioned Japanese Laid-Open Patent Publication, both vibration detection and vibration may be performed by one piezoelectric element.

However, in this case, since one piezoelectric element is also used for vibration detection and vibration, the detection efficiency or vibration efficiency is deteriorated. Further, as a result of the detection signal and the vibration signal affecting each other, accurate vibration detection cannot be performed, and therefore vibration also becomes inaccurate. Therefore, deterioration of vibration damping performance cannot be avoided.

An object of the present invention is to solve the above problems and improve the vibration damping performance of the vibration damping device.

[0008]

In order to solve the above problems, in the present invention, two piezoelectric elements are used, a first piezoelectric element for vibration detection and a second piezoelectric element for vibration. The first and second piezoelectric elements are arranged in series so that pressure is transmitted between both elements.

The first and second piezoelectric elements may be adhered and integrated, but it is desirable to integrally form them from the beginning with an electrode interposed therebetween.

Further, the vibration damping device of the present invention includes a control circuit which receives a detection signal from the first voltage element and outputs a vibration signal to the second piezoelectric element based on the signal, if necessary. A correction circuit for subtracting the vibration component due to the vibration of the second piezoelectric element from the detection signal of the first piezoelectric element is added to the control circuit, and the signal passing through this correction circuit is used for the vibration control as the signal of the brake vibration. The configuration is also preferable.

[0011]

Since the first piezoelectric element for vibration detection and the second piezoelectric element for vibration are arranged in series, the pressure applied to both elements is always the same regardless of the assembly accuracy, and the two elements are pressed against each other. The problem of performance deterioration due to the difference in force does not occur.

Further, since the vibration detection and the vibration are performed at the same place by the serial arrangement, the control is stable. If the detection point and the excitation point are different, the brake vibrations at both positions do not always match, so there may be a deviation in the excitation control, but that problem does not occur.

Further, since the vibration detection and the vibration are performed by the separate piezoelectric elements, the accuracy of the detection and the vibration is increased, and the efficiency is improved.

According to the structure of claim 2 in which the first and second piezoelectric elements are integrally formed via the electrodes, the step of adhering the two elements is unnecessary, and further, apparently one element is formed. Since it becomes an element, its handling is also improved.

According to the third aspect of the invention in which the correction circuit is added to the control circuit, the vibration component of the second piezoelectric element included in the detection signal of the first piezoelectric element is removed, so that the brake vibration is suppressed. The detection accuracy is improved, and the accuracy of vibration applied based on the brake vibration signal is increased.

[0016]

FIG. 1 shows a first embodiment of the present invention. In the figure, 1 is a disc, 2 is a floating caliper, 3 is a pad for sliding contact with the disc, 4 is a brake piston, 5 is a piston seal, and 6 is a piston boot. An exemplary vibration damping device provided in this floating disc brake includes a first piezoelectric element 7 for detecting vibration, a second piezoelectric element 8 for vibration, an element pressing tool 9, and a control circuit 10. The first and second piezoelectric elements 7 and 8 are
As shown in the figure, these elements are arranged in series in the brake piston 4, and these elements are pressed against the back surface of the pad 3 by the retainer 9 that receives the thrust of the brake piston 4 to perform vibration detection and vibration. I have to. The control circuit 10 inputs the signal voltage (detection signal) sent from the first piezoelectric element 7 to detect the frequency, phase and level of the brake vibration,
The signal subjected to the gain adjustment and the phase adjustment is sent to the second piezoelectric element 8 as an excitation signal. In response to the excitation signal, the second piezoelectric element 8 applies vibration to the pad 3 in a direction of canceling the brake vibration, thereby reducing the brake vibration.

In the device shown in the figure, the piezoelectric elements 7 and 8 are provided in the brake piston 4, but these elements may be arranged in the caliper, and the second piezoelectric element 8 is provided on the caliper side. The same effect can be obtained with a configuration in which the first piezoelectric element 7 is placed behind the first piezoelectric element 7.

As the first and second piezoelectric elements 7 and 8, separate ones may be used by being adhered, or an integrated type as shown in FIG. 2 may be used. FIG. 2A shows an example in which a single layer type element is used, and the first piezoelectric element 7 uses the piezoelectric material 7a as the electrode 7
It is composed by sandwiching b and 7c. The second piezoelectric element 8 is composed of a piezoelectric material 8a sandwiched between electrodes 8b and 7c, and is functionally divided by a common electrode 7c.

FIG. 2B shows an example using a laminated type element, and in this case as well, it is functionally divided into two elements.
Since these two elements are apparently one,
It is easy to handle and can save the labor of bonding.

FIG. 3 shows a concrete example of the control circuit 10 having a correction circuit. The control circuit 10 creates a vibration detection circuit 11 that detects the frequency, phase, and level of the signal from the first piezoelectric element 7 and a vibration signal that has been subjected to gain adjustment and phase adjustment, and then generates the excitation signal. It is configured by adding a correction circuit including a correction signal adjustment circuit 13 and a differential circuit 14 to a general control circuit including the excitation signal output circuit 12 for outputting to.

As in the present invention, the first and second piezoelectric elements 7,
When 8 are arranged in series, the vibration detected by the first piezoelectric element 7 is not only the target brake vibration (pad vibration) but also the vibration generated by the second piezoelectric element 8 being applied thereto (this is an error). Component) is superimposed. If this error component is large, the ratio of the error component in the detection signal becomes large, the detection accuracy deteriorates, and the vibration control deviates from the optimum control.

Therefore, the correction signal adjusting circuit 13 produces a correction signal for removing the error component, and the differential circuit 14
In the above, the correction signal is subtracted from the signal detected by the first piezoelectric element 7, and the vibration signal after the error component is removed is output to the vibration signal output circuit 12 for vibration control.

Since the vibration of the second piezoelectric element 8 is proportional to the excitation signal, the correction signal adjusting circuit 13 adjusts the gain of the excitation signal, and the adjusted signal is included in the detection signal of the first piezoelectric element 7. This is made a correction signal by making it equal to the vibration component due to the vibration in the included element 8. In addition, this circuit 1
Within 3, if there is a phase difference between the vibration signal and the vibration component due to vibration in the detection signal, the difference is also corrected.

Next, the gain adjustment when creating the correction signal will be described. There are two methods of this adjustment, 1) and 2) below.

1). Method by Calculation The characteristic that the detecting piezoelectric element converts the vibration X1 into the voltage value V1 is known, and the voltage V applied to the exciting piezoelectric element is V.
The characteristic of converting from 2 to vibration X2 is also known, and these are represented by the following equation. V1 = K1 * X1, X2 = K2 * V2 where K1 and K2 are known constants, and when considering the output V1 (= correction signal) of the detection piezoelectric element due to the vibration X2 of the vibration piezoelectric element, X1 Since it suffices to set X2, V1 = (K1 * K2) * V2. That is, since V2 is the excitation signal, K1 * K2
Is the gain for adjusting the excitation signal.

2). Method by Experiment An AC signal is applied to the vibration piezoelectric element to vibrate a certain object to be measured, and the vibration of this object to be measured is detected by vibration detecting means other than the first piezoelectric element of the present invention. The gain is adjusted so that the signal becomes equal to the signal detected by the first piezoelectric element of the present invention.

The vibration due to the vibration of the element 8 is small,
If the ratio of the vibration component due to the vibration in the detection signal is sufficiently small, the correction circuit is unnecessary.

[0028]

As described above, according to the present invention, the first piezoelectric element for vibration detection and the second piezoelectric element for vibration are arranged in series. Therefore, when both elements are arranged in parallel, the element is pressed. There is no problem of performance deterioration due to force imbalance and cost increase when performing high precision machining to balance pressing force.

In addition, when one piezoelectric element is used for both vibration detection and vibration, performance deterioration due to deterioration of detection / vibration efficiency and performance deterioration due to mutual influence of detection signal and vibration signal, The problem of deterioration of control accuracy due to the displacement between the detection point and the excitation point is also solved, and the performance of the vibration damping device that damps brake vibration and stops squealing can be further improved.

Further, in the case where the two piezoelectric elements are integrally formed, the bonding step is unnecessary and the handling of the elements is improved.

Further, the control circuit to which a correction circuit is added exhibits an excellent vibration damping effect by accurately detecting the vibration even if the vibration generated by the vibration is large.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a vibration damping device of the present invention in a use state.

FIG. 2A is a diagram showing an example of an integrated piezoelectric element. FIG. 2B is another diagram showing an integrated piezoelectric element.

FIG. 3 is a block diagram showing an example of a control circuit to which a correction circuit is added.

[Explanation of symbols]

 1 Disc 2 Caliper 3 Pad 4 Brake Piston 7 First Piezoelectric Element 7a Piezoelectric Material 7b, 7c Electrode 8 Second Piezoelectric Element 8a Piezoelectric Material 8b Electrode 9 Element Holding Tool 10 Control Circuit 11 Vibration Detection Circuit 12 Excitation Signal Output Circuit 13 Correction Signal conditioning circuit 14 Differential circuit

Claims (3)

[Claims] 1. A brake vibration is detected from a pad using a first piezoelectric element, and a control circuit outputs a second vibration based on the detection signal.
A vibration damping device for a disc brake, which outputs a vibration signal to a piezoelectric element and vibrates a pad by the second piezoelectric element so as to cancel the brake vibration, wherein the first piezoelectric element and the second piezoelectric element are both elements. A vibration damping device for a disc brake, wherein the vibration damping devices are arranged in series so that pressure is transmitted between them. 2. The vibration damping device for a disc brake according to claim 1, wherein the first piezoelectric element and the second piezoelectric element are integrated with an electrode interposed therebetween. 3. A correction circuit for subtracting a vibration component due to vibration of the second piezoelectric element from a detection signal of the first piezoelectric element is added to the control circuit, and a signal passing through the correction circuit is added as a signal of brake vibration. The vibration damping device for a disc brake according to claim 1 or 2, wherein vibration control is performed.