JP2005147291A - Bush with stress sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable measurement of stress to a rubber bush without shortening the life of the rubber bush. <P>SOLUTION: A bush 10 attached to a bearing portion of a connecting member provided between a tire and a chassis of a vehicle is configured so that a notch part 13a is provided on the outer peripheral face of an inner cylinder 13 or the inner peripheral face of an outer cylinder 11 which sandwich a rubber bush 12; that a piezoelectric element 14 is embedded in the notch part 13a; that the surface of the piezoelectric element 14 is closely contacted with the rubber bush 12; and thus that the stress generated in the rubber bush 12 when external force is loaded on the tire is measured with the piezoelectric element 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a bush with a stress sensor, and more particularly to a tire external force obtained by measuring a stress on a rubber bush installed in a connecting portion provided between a tire of a vehicle such as an automobile and a chassis. .

  Conventionally, rubber bushes that can absorb changes in vehicle height due to bouncing wheels are often installed in bearing portions in the vicinity of automobile suspensions. For example, in Japanese Utility Model Laid-Open No. 6-65019, as shown in FIG. 8, the suspension member 1 and the transverse link are provided via a swing member 2 in which a rubber bush 2b is interposed between the outer cylinder 2a and the inner cylinder 2c. 3 are connected. The inner cylinder 2c is fixed to the suspension member 1, and the outer cylinder 2a is fixed to the transverse link 3 and the potentiometer 4 is fixed. The potentiometer 4 is fixed to the suspension member 1 via a second swing member 5 with a slider 4a slidingly contacting the outer periphery of the potentiometer body 4b.

When measuring the stress applied to the rubber bush 2b in order to measure the force (tire external force) generated between the ground and the tire for stable running of the vehicle, a sensor such as a piezoelectric element is inserted into the rubber bush 2b. It is also possible to insert a piezoelectric element between the rubber bush 2b and the inner cylinder 2c. However, if a foreign substance is put in the rubber or the rubber is locally pressed, the rubber easily breaks from the portion, and there arises a problem that the life of the rubber bush 2b is shortened.
Japanese Utility Model Publication No. 6-65019

  This invention is made | formed in view of the said problem, and makes it the subject to make it possible to measure the stress to a rubber bush, without shortening the lifetime of a rubber bush.

In order to solve the above problems, the present invention is a bush mounted on a bearing portion of a connecting member provided between a vehicle tire and a chassis,
A notch is provided on the outer peripheral surface of the inner cylinder holding the rubber bush or the inner peripheral surface of the outer cylinder. The piezoelectric element is embedded in the notch and the surface of the piezoelectric element is brought into close contact with the rubber bush so that an external force is applied to the tire. There is provided a bush with a stress sensor characterized in that a stress generated in the rubber bush when measured is measured by the piezoelectric element.

  With the above configuration, since the piezoelectric element is embedded in the cutout portion of the inner cylinder or the outer cylinder, the piezoelectric element is not inserted into the rubber bush, and the piezoelectric element does not press the rubber bush locally. Since the piezoelectric element can be brought into contact with the rubber bush, stress on the rubber bush can be measured without affecting the life of the rubber bush. Based on the measured stress on the rubber bush, the tire external force can be calculated and fed back to the vehicle vibration control for use in stable running.

  The notch is cut in the axial direction from the end of the inner cylinder or the outer cylinder, and the piezoelectric element is embedded in a part of the notch and an electric wire connected to the piezoelectric element is passed through the notch. Derived from the end.

  With the above configuration, when it is desired to bring the piezoelectric element into contact with an arbitrary position in the axial direction of the inner surface or outer peripheral surface of the rubber bush, for example, when the piezoelectric element is brought into contact with the central position in the axial direction of the rubber bush. By leading the electric wire connected to the element through the notch, the electric wire can be prevented from interfering with the rubber bush, and the life of the rubber bush can be prevented from being reduced.

  The notch is preferably filled with an insulating material in the remaining space in which the piezoelectric element is embedded, and the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder is preferably a smooth surface without a step.

With the above configuration, since the remaining space in which the piezoelectric element in the notch is embedded is filled with an insulating material, the step formed by notching the inner cylinder or the outer cylinder is eliminated, and a smooth surface without an edge is maintained. be able to. Therefore, it is possible to prevent the rubber bush from being excessively damaged and prevent the life of the rubber bush from being reduced.
As the insulating material, a resin or the like is preferably used, and considering an external force applied to the rubber bush by the tire external force, it is preferable that the material does not distort by 0.1% or more even when a force of 50000 N is applied.

  As is clear from the above description, according to the present invention, since the piezoelectric element is embedded in the cutout portion of the inner cylinder or the outer cylinder, the piezoelectric element can be rubberized without locally pressing the rubber bush. The bush can be brought into contact with each other, and the life of the rubber bush can be prevented from being reduced. Moreover, the electric wire connected to the piezoelectric element can be led out along the notch, so that interference with the rubber bush can be prevented, thereby contributing to prevention of a decrease in the life of the rubber bush. Furthermore, by filling the remaining space of the notch with an insulating material, the step of the inner cylinder or the outer cylinder can be eliminated, and the rubber bush can be prevented from being damaged.

A first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a bush 10 with a stress sensor used in a bearing portion that is a connecting portion between a tire and a chassis of an automobile, and a rubber bush 12 is interposed between a metal outer cylinder 11 and an inner cylinder 13. The bolt 16 inserted into the inner cylinder 13 is fixed to the inner cylinder support member 17, and the outer cylinder 11 is press-fitted and fixed to a cylindrical hole provided in the outer cylinder support member 18. In other words, the inner cylinder support member 17 is connected to a tire side part (or chassis side part), while the outer cylinder support member 18 is connected to a chassis side part (or tire side part), so The rubber bush 12 absorbs the relative displacement between the tube support member 17 and the outer tube support member 18.

As shown in FIGS. 1 to 3, the inner cylinder 13 is provided with a notch 13 a on the outer peripheral surface from the end 13 b to the vicinity of the center in the axial direction, and the piezoelectric element 14 at the center end of the notch 13 a. The two electric wires W connected to the piezoelectric element 14 are led out from the end 13b of the inner cylinder 13 along the notch 13a.
One of the two electric wires W is a signal line for extracting a voltage signal from the piezoelectric element 14, and the other is a ground wire. Therefore, the electric wire led out from the piezoelectric element 14 may be only one signal line.

  The remaining space other than the embedding of the piezoelectric element 14 in the notch 13a is filled with an insulating material 15 so that the outer peripheral surface of the inner cylinder 13 is a smooth surface without a step. The insulating material 15 is preferably a material that does not distort by 0.1% or more even when a force of 50000 N is applied in consideration of an external force applied to the rubber bush 12 by a tire external force, and a resin such as polycarbonate is suitably used.

With the above configuration, the stress applied to the rubber bush 12 when the shaft 16 is displaced due to the force (tire external force) generated between the tire and the ground of the automobile is detected by the piezoelectric element 14 in contact with the rubber bush 12. Can be converted into a voltage signal and the signal can be taken out via the electric wire W.
Moreover, since the piezoelectric element 14 is embedded in the cutout portion 13a of the inner cylinder 13, the piezoelectric element 14 can be brought into contact with the rubber bush 12 without locally pressing the rubber bush 12. It does not affect the life of the rubber bush 12.

  Further, since the electric wire W connected to the piezoelectric element 14 disposed at the center position in the axial direction is led out along the notch 13a to prevent interference with the rubber bush 12, the life of the rubber bush 12 is reduced. Can be prevented. In addition, since the remaining space other than the piezoelectric element 14 embedded in the cutout portion 13a is filled with the insulating material 15, the step due to the cutout portion 13a formed by cutting out the inner cylinder 13 is eliminated and the edge is smooth. Thus, the rubber bush 12 can be prevented from being damaged.

  FIG. 4 shows an example of use, wherein the first to third stress sensor-equipped bushes 10 </ b> A to 10 </ b> C are connected to an ECU (Electronic Control Unit) 20 via an amplifier 21. Specifically, one of the two electric wires W led out from the piezoelectric elements 14 of the bushes 10A to 10C with first to third stress sensors provided at various locations in the automobile is connected to the amplifier 21 to amplify the signal. And connected to the ECU 20. Then, a predetermined calculation is performed based on the stress information to the rubber bush 12 acquired by the ECU 20, the tire external force is calculated, and the vehicle is stably fed back to the vibration control of the vehicle. The other of the electric wires W led out from the piezoelectric element 14 is grounded, and the amplifier 21 is also grounded.

  Further, FIG. 5 shows a modified use example, where the twisted wire W ′ is used as a twisted wire W ′ between the piezoelectric element 14 and the amplifier 21 to make it difficult for noise, and both ends are open (not cut) on the outer periphery of the twisted wire W ′. It is also preferable to apply a shield S and ground one end of the shield S. Needless to say, the ground portion may be an end portion on the piezoelectric element 14 side instead of one end on the amplifier 21 side.

6 and 7 show a second embodiment.
The difference from the first embodiment is that a notch 11a ′ for embedding the piezoelectric element 14 is provided in the outer cylinder 11 ′ instead of being provided in the inner cylinder 13 ′.

  The outer cylinder 11 ′ is provided with a notch 11a ′ from the end 11b ′ to the vicinity of the center in the axial direction on the inner peripheral surface thereof, and the piezoelectric element 14 is embedded at the center end of the notch 11a ′. Two electric wires W connected to the piezoelectric element 14 are led out from the end portion 11b ′ of the outer cylinder 11 ′ along the notch portion 11a ′. The remaining space other than the piezoelectric element 14 embedded in the notch 11a 'is filled with an insulating material 15, so that the inner peripheral surface of the outer cylinder 11' becomes a smooth surface without a step. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

It is sectional drawing of the bush with a stress sensor of 1st Embodiment of this invention. It is the sectional view on the AA line of FIG. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is a block diagram which shows the usage example of a bush with a stress sensor. It is drawing which shows the modification usage example. It is sectional drawing of the bush with a stress sensor of 2nd Embodiment. It is CC sectional view taken on the line of FIG. It is drawing which shows a prior art example.

Explanation of symbols

10 Bush with stress sensor 11 Outer cylinder 12 Rubber bush 13 Inner cylinder 13a Notch 13b End 14 Piezoelectric element 15 Insulating material 20 ECU
21 Amplifier W Electric wire

Claims (3)

A bush mounted on a bearing portion of a connecting member provided between a vehicle tire and a chassis,
A notch is provided on the outer peripheral surface of the inner cylinder holding the rubber bush or the inner peripheral surface of the outer cylinder. The piezoelectric element is embedded in the notch and the surface of the piezoelectric element is brought into close contact with the rubber bush so that an external force is applied to the tire. A bush with a stress sensor, wherein the stress generated in the rubber bush when measured is measured by the piezoelectric element.   The notch is cut in the axial direction from the end of the inner cylinder or the outer cylinder, and the piezoelectric element is embedded in a part of the notch and an electric wire connected to the piezoelectric element is passed through the notch. The bush with a stress sensor of Claim 1 which has led out from the said edge part.   The remaining portion in which the piezoelectric element is embedded is filled in the notch with an insulating material, and the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder is a smooth surface having no step. Item 3. A bush with a stress sensor according to Item 2.

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