JP2778144B2 - Vehicle damping force detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle damping force detector for detecting a damping force of a shock absorber of a vehicle.

[Prior Art] Conventionally, as a vehicle damping force detector, a piezoelectric element is housed in a metal container, a predetermined torque is applied in advance by screwing a cap, and the piezoelectric element is fixed in the metal container. There has been known a detector configured to output an electric signal in response to vibration applied to a metal container (for example, Japanese Utility Model Publication No. 57-45539).

However, it is difficult to detect subtle vibrations (changes in load) because the level of the electric signal output by one piezoelectric element is small and the signal component is often smaller than noise (small S / N ratio). Met.

Therefore, it has been considered to increase the electric signal level and increase the detection accuracy of the damping force by stacking a plurality of piezoelectric elements. For example, a damping force sensor formed by laminating a plurality of ring-shaped piezoelectric elements (for example, piezo elements) is incorporated into a hollow portion formed inside a piston rod of a vehicle shock absorber, and a piston is formed. A damping force detector configured to detect a subtle damping force applied to a rod has been developed.

[Problems to be Solved by the Invention] However, in the above-described damping force detector, the upper and lower portions of the damping force sensor are simply housed in an insulating case, and therefore, depending on weather conditions, a piezoelectric element or an electrode may be used. Water condensation on the plate causes the charge generated on the piezoelectric element to leak to the metal housing, etc., and the output of the damping force sensor may decrease or become unstable, resulting in a decrease in the detection accuracy of the damping force. there were.

Therefore, an object of the present invention is to provide a vehicle damping force detector using stacked piezoelectric elements to prevent leakage of electric charges due to dew condensation or the like and increase the detection accuracy of the damping force.

[Means for Solving the Problems] The gist of the present invention is to provide a laminate in which a plurality of piezoelectric elements are laminated and provided with an electrode for combining and outputting output charges of each piezoelectric element; A container for accommodating the body and being assembled to the piston rod of the shock absorber and transmitting a part of the damping force received from the piston rod to the laminated body; and a vehicle body from the shock absorber via the piston rod. A damping force detector for a vehicle that detects damping force transmitted to the container using the laminate, wherein the container has an opening, and one end of the laminate in the stacking direction is exposed to the opening. A box body capable of storing the laminated body as described above, and a fitting formed to fit into the opening of the box to close the opening, and to be slidable in the fitting direction with respect to the box. And the above A vehicle which is formed separately from the ton rod, and further provided with a sealing member for keeping the inside of the container airtight at a fitting portion between the box body and the fitting body, so that the container is a sealed container. In the damping force detector.

[Operation] According to the present invention configured as described above, when a load is applied to the laminate, electric charges are generated in each voltage element, and electric charges of each piezoelectric element are combined and output by the electrodes. That is, the output charge of the stacked body is the sum of the charges of each piezoelectric element. This laminate is housed in a closed container consisting of a box and a fitting body, and a seal member provided at a fitting portion between the two keeps the inside of the closed container airtight. Therefore, the laminate does not come into contact with the outside air.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a sectional view showing the entire structure of a vehicle damping force detector.

As shown in the figure, the vehicle damping force detector 1 is composed of a sensor unit 3 and an upper case 5 and a lower case 7 as hermetically sealed containers that house the sensor unit 3 in an airtight manner. (Not shown) in the hollow portion 11 of the piston rod 9 and the rod screw 13
Is fixed in a state of being tightened with a torque of a predetermined magnitude.

As shown in FIG. 2 and FIG.
Are three piezo elements 22a, 22b formed in a ring shape,
Four electrode plates 24 having substantially the same shape as 22c and the piezo elements 22a to 22c.
a, 24b, 24c, and 24d are alternately stacked; a ring-shaped insulating disk 30a, 30b that insulates the electrode plates 24a and 24b from the upper case 5 and the lower case 7; A cylindrical insulating insulator 32 which is provided and insulates the laminated body 20 from the lower case 7 is mainly constituted.

Each of the electrode plates 24a and 24c has three L-shaped terminals
Ta1, Ta2, Ta3 and Tc1, Tc2, Tc3 are provided, and their terminals (Ta1 and Tc1, Ta2 and Tc2, Ta3 and Tc3) are aligned on the same line in the axial direction (vertical direction in FIG. 2). Are located in Three L-shaped terminals Tb1, Tb2, Tb3 and Td1, Td2, Td3 are also provided on the electrode plates 24b and 24d, respectively, and the respective terminals (Tb1 and Td1, Tb2 and Td2, Tb3
And Td3) are arranged so as to be aligned on the same line in the axial direction. The aligned terminal rows are bent so as to face each other, and are joined by the side electrodes 34a, 34b, 34c, 34d. Also, lead wires 36a and 36b are connected to the electrode plates 24a and 24d, which are end faces of the laminate 20, respectively, so that electric charges generated in the piezo elements 22a to 22c can be led to an external signal processing circuit (not shown). Is configured.

The upper case 5 and the lower case 7 are cylindrical metal cases. The lower case 7 can be fitted to the upper case 5 and the upper case 5 can slide in the fitting direction. Then, after the stack 20 is placed in the lower case 7 and the upper case 5 is put on, the upper case 5 and the lower case 7 are integrally formed to form a closed container. A groove 7a is engraved on the side surface circumference of the lower case 7, and an O-ring 40 as a sealing member is fitted therein, so that outside air flows into the inside from between the upper case 5 and the lower case 7. There is no seal. The lead wires 36a, 36b are drawn out through the bushings 42a, 42b fitted in the holes formed in the bottom of the lower case 7, and are drawn out to the through holes 9a of the piston rod 9, so that the outside air can escape from here. Sealed to prevent inflow.

Since the depth of the lower case 7 is such that the laminated body 20 slightly protrudes, the upper case 5 directly contacts the sensor unit 3 and the tightening torque of the rod screw 13 is directly applied to the sensor unit 3. To join.

In the vehicle damping force detector 1 configured as described above,
Most of the damping force of the shock absorber is transmitted from the piston rod 9 to the vehicle body (not shown), but a part of the damping force is transmitted from the piston rod 9 to the sensor unit 3 via the rod screw 13 to each piezo. Elements 22a to 22c
Distorts. The charge generated in each of the piezo elements 22a to 22c is
It is collected by the electrode plates 24a to 24d and output to an external signal processing circuit via the lead wires 36a and 36b. That is, since a plurality of piezo elements 22a to 22c are stacked, the output charge as a whole is doubled as compared with a single piezo element.

Also, due to the distortion of the piezo elements 22a to 22c, the upper case 5 slightly slides on the fitting surface with the lower case 7 (the inner wall of the upper case 5 and the outer wall of the lower case 7). Outside air cannot enter the lower case 7 because it is sealed.

As described above, in the present embodiment, a plurality of piezoelectric elements
Since the layers 22a to 22c are stacked, a sufficient charge can be output. Therefore, it is possible to obtain an electric signal having a good S / N ratio.

Further, since a package structure in which the sensor unit 3 is housed in the upper case 5 and the lower case 7 is employed, and the seal is completely formed using the O-ring 40 and the bushes 42a and 42b, Even when the damping force detector 1 is used in an atmosphere such as high humidity or dust,
Dew condensation and foreign matter can be prevented, and accidents such as charge leakage and short circuit between electrode plates do not occur. Therefore, the output of the vehicle damping force detector 1 does not decrease due to charge leakage or short circuit, and the damping force of the shock absorber can be accurately detected.

In the present embodiment, the sensor unit 3 is tightened with the rod screw 13. At this time, the lower case 7 is prevented from rotating with respect to the upper case 5.
You may fix using a lock pin.

Although the rod screw 13 and the upper case 5 are in surface contact with each other, the contact surface of the upper case 5 is made convex, and the contact surface of the rod screw 13 is finished concave, so that the piezo elements 22a to 22c have a more uniform damping force. You may comprise so that it may join 22c.

Further, a metal dummy of the same shape is disposed outside the insulating disks 30a and 30b, and stress is concentrated on the insulating disks 30a and 30b due to burrs remaining on the inner walls of the upper case 5 and the lower case 7. Alternatively, each part of the sensor unit 3 may be prevented from being damaged.

Next, in the present embodiment, the sensor unit 3 is housed in the hollow portion 11 of the piston rod 9 and is fastened and fixed by the rod screw 13. However, the sensor unit 3 may be directly tightened by the upper case.

That is, as shown in FIG. 4, a male screw 50a is cut on the outer periphery of the upper case 50, a female screw 60b is cut on the inner wall of the hollow portion 60a of the piston rod 60, and a slit 50b formed on the upper surface of the upper case 50 is cut. By rotating the upper case 50 with a driver (not shown) or the like, the sensor unit 62 is rotated.
To secure. During this tightening, the upper case
Lock pin 54 so that 50 and lower case 52 do not rotate.
Is provided. In addition, the lead wire 56
a, 56b are fixed to the lower case 52, and the lead wires
The strength of the 56a, 56b against tension may be compensated.

Further, as shown in FIG. 5, a cylindrical hole 70 is formed at the bottom center of each of the upper case 70 and the lower case 72.
a, 72a, and a through hole 74a formed in the center of the rod screw 74 so that an electric wire (not shown) can be drawn in from the outside of the piston rod 76 and connected to the sensor unit 80. Good. In this case, an O-ring 82b is provided on the inner wall of the hole 72a of the lower case 72 in addition to the O-ring 82a already provided, so that the sensor unit 80 can be stored in an airtight manner. Also, the sensor unit
In addition to the insulating insulator 84a disposed on the outer periphery of the outer casing 80, the insulating insulator 84b is also provided on the inner peripheral surface of the lower case 72.
To ensure complete insulation.

[Effects of the Invention] As described in detail above, according to the vehicle damping force detector of the present invention, the container for assembling the laminated body of the piezoelectric elements for damping force detection to the piston rod of the shock absorber has an opening. A piston rod is formed separately from the piston rod by a box body having the housing and a fitting body which is fitted into the opening of the box to close the opening, and is slidable in the fitting direction with respect to the box. ,
In addition, a seal member for keeping the inside of the container airtight is provided at a fitting portion between the box and the fitting body of the container. For this reason,
The container (closed container) completely shields the laminate from the outside air, so that the damping force can be accurately detected even when used in an atmosphere such as high humidity or dust.

Further, in the present invention, since the sealed container for storing the laminated body is configured separately from the piston rod, compared with the case where the piston rod itself is used as a part of the container for storing the laminated body, The airtightness of the container can be improved. In other words, it is possible to use the piston rod as a part of the container when assembling the laminated body to the piston rod of the shock absorber, but in this case, the airtightness of the container is reduced due to distortion of the piston rod itself. Can be considered. However, according to the present invention, the hermeticity of the sealed container is not impaired by the distortion of the piston rod itself, the hermeticity of the container is reduced, and the detection accuracy of the damping force is reduced. Can be prevented.

[Brief description of the drawings]

1 is a sectional view of a vehicle damping force detector, FIG. 2 is a perspective view of a sensor unit, FIG. 3 is a side view of the sensor unit,
FIG. 4 is a cross-sectional view of another embodiment in which the upper case also serves as a rod screw, and FIG. 5 is a cross-sectional view of another embodiment in which a lead wire can be drawn out of the rod. 1 ... vehicle damping force detector, 3 ... sensor unit, 5
…… Upper case 7 …… Lower case 20 …… Laminated body, 22
a, 22b, 22c: Piezo element, 24a, 24b, 24c, 24d: Electrode plate, 40: O-ring, 42a, 42b: Bush

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-6238 (JP, A) JP-A-63-109053 (JP, U) JP-A-63-146734 (JP, U) (58) Investigation Field (Int.Cl. ⁶ , DB name) G01L 1/16 B60G 17/00 F16F 9/32

Claims (1)

(57) [Claims] 1. A laminated body in which a plurality of piezoelectric elements are laminated and provided with electrodes for synthesizing and outputting output charges of each piezoelectric element, and accommodating the laminated body and assembling the piston rod of a shock absorber. A container that transmits a part of the damping force received from the piston rod to the laminate, and a damping force transmitted to the vehicle body from the shock absorber via the piston rod by using the laminate. A vehicular damping force detector for detecting, wherein the container has an opening, and a box body capable of storing the laminate such that one end of the laminate in the laminating direction is exposed to the opening. A fitting body that fits into the opening of the box and closes the opening, and that is formed to be slidable in the fitting direction with respect to the box; And the above-mentioned box and A damping force detector for a vehicle, wherein a seal member for keeping the inside of the container airtight is provided at a fitting portion with the fitting body, and the container is a sealed container.