JPH0371029A - Damping force detector for vehicle - Google Patents

Abstract

PURPOSE:To accurately detect a damping force even when the detector is used in an atmosphere of high humidity, dust, etc., by housing a laminate body in a sealed container in which the outdoor is prevented by an O ring from flowing. CONSTITUTION:The laminate body 20 is housed in the sealed container in which the outdoor air is prevented by the O ring 40 from flowing. In the detector 1, the majority of the damping force of a shock absorber is transmitted from a piston rd 9 to a vehicle body, but the rest of the damping force is sent from the rod 9 to a sensor unit 3 through a rod screw 13 to be distorted respective piezoelectric elements 22a - 22c. Further, charges which are generated by the elements 22a - 22c are collected by electrode plates 24a - 24d and outputted to an external signal processing circuit through lead wires 36a and 36b. Further, an upper case 5 slides slightly in a lower case 7 as the elements 22a - 22c are distorted, but the container is sealed by the O ring, so no outdoor air flows in the case 7. Therefore, the damping force can accurately be detected even when the detector is used in a high-humidity atmosphere, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a damping force detector for a vehicle that detects the damping force of a shock absorber of a vehicle.

[Prior Art] Conventionally, as a damping force detector for a vehicle, a piezoelectric element is housed in a metal container, and the piezoelectric element is fixed in the metal container by applying a predetermined torque by tightening a screw on a cap. A detector is known that is configured to output a color electric signal in response to one vibration applied to a metal container (for example, Japanese Utility Model Publication No. 57-45539).

However, the level of the electrical signal output by the piezoelectric element is small, and the signal component is often smaller than the noise (small S/N ratio), making it difficult to detect minute vibrations (load changes). Therefore, it has been considered to stack a plurality of piezoelectric elements to increase the electrical signal level and improve the detection accuracy of the damping force. For example, a damping force sensor formed by stacking a plurality of ring-shaped piezoelectric elements (for example, piezo elements) is installed in a hollow part drilled inside the piston rod of a vehicle shock absorber. A damping force detector configured to be able to detect even minute damping forces applied to a rod has been developed.

[Problems to be Solved by the Invention] However, in the above damping force detector, the upper and lower parts of the damping force sensor are simply housed in an insulating case, so depending on the weather conditions, the piezoelectric element or electrode may Moisture condenses on the plate, and the electric charge generated in the piezoelectric element leaks into the metal housing, etc. This may cause the output of the damping force sensor to decrease or become unstable, resulting in a problem of reduced damping force detection accuracy. SUMMARY OF THE INVENTION Therefore, the present invention was made for the purpose of improving the detection accuracy of damping force by preventing charge leakage due to dew condensation in a vehicle damping force detector using laminated piezoelectric elements. ] The gist of the present invention is to provide: a laminate in which a plurality of piezoelectric elements are stacked and provided with an electrode for synthesizing and outputting the output charge of each piezoelectric element; a box having an opening; and the opening. a fitting body that fits into the opening to close the opening, and at least the box body or the fitting body is formed so as to be slidable in the fitting direction; A damping force detector for a vehicle, comprising: a sealing member provided therein to keep the inside of the hermetic container airtight; and the laminate is housed in the hermetic container.

[Operation] According to the present invention configured as described above, when a load is applied to the laminate, charges are generated in each piezoelectric element, and the charges of each piezoelectric element are combined by the electrodes and output. That is, the output charge of the laminate is the sum of the charges of each piezoelectric element. This laminate is housed in an airtight container consisting of a box and a fitting body, and a seal member disposed at the fitting portion of the two keeps the inside of the airtight container airtight. Therefore, the laminate is not exposed to outside air.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

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

As shown in the figure, the vehicle damping force detector 1 is composed of a sensor unit 3, an upper case 5 and a lower case 7 as airtight containers that airtightly house the sensor unit 3, and includes a vehicle shock absorber (not shown). The piston rod 9 is housed in the hollow part 11 of the piston rod 9, and is fixed by being tightened with a predetermined torque by a rod screw 13.

As shown in FIGS. 2 and 3, the sensor unit 3
Three piezo elements 22a, 22 formed in a ring shape
b, 22c and 4 having almost the same shape as the piezo elements 22a to 22C.
A laminate 20 in which electrode plates 24a, 24b, 24c, and 24d are alternately stacked, ring-shaped insulating disks 30a and 30b that insulate the electrode plates 24a and 24b from the upper case 5 and the lower case 7, and the laminate The main part is a cylindrical insulating insulator 32 that is disposed around the outer periphery of the laminate 20 and insulates the laminate 20 from the lower case 7.

The electrode plates 24a and 24c each have three L-shaped terminals Tal, Ta2, Ta3 and Tcl, Tc2, Tc.
3 is provided. Each terminal is connected to each other (Tal and Tcl,
T'a2 and Tc2, Ta3 and Tc3) are in the axial direction (second
They are arranged on the same line in the vertical direction (in the figure). The electrode plates 24b and 24d also have three L-shaped terminals Tbl, Tb2, Tb3 and Tdl, Ta, respectively.
2. Ta3 is provided. The respective terminals (Tb1 and Tdl, Tb2 and Ta2, Tb3 and Ta3) are arranged on the same line in the axial direction.

Then, the aligned terminal rows are bent to face each other, and the side electrodes 34a, 34b, 34C234d
are joined by. Further, the electrode plates 24a and 24d, which are the end faces of the laminate 20, are each connected to a lead wire 3.
6a and 36b are connected, piezo elements 22a to 22c
The structure is such that the electric charges generated in the circuit can be guided to an external signal processing circuit (the path shown in the figure).

The upper case 5 and the lower case 7 are cylindrical metal cases, and the lower case 7 can be fitted into the upper case 5, and the upper case 5 can be slid in the fitting direction. Therefore, when the upper case 5 is placed on the lower case 7 after storing the laminate 20 therein, the upper case 5 and the lower case 7 are integrated to form a sealed container.

Further, a groove 7a is carved in the circumference of the side surface of the lower case 7, and an O-ring 40 as a sealing member is fitted into the groove 7a, so that outside air can flow into the interior from between the upper case 5 and the lower case 7. It is sealed to avoid any damage. The lead wires 36a, 36b are connected to bushings 4.2a, 4 fitted into holes drilled in the bottom of the lower case 7.
2bu and is pulled out to the through hole 9a of the piston rod 9, so it is sealed to prevent outside air from flowing in from here as well.

Since the depth of the lower case 7 is such that the stacked body 20 slightly protrudes, the upper case 5 comes into direct contact with the sensor unit 3, and the rod screw 13 is tightened by Die [No. 1-] is designed to be added to Senzakornit 3.

In the vehicle damping force detector 1 configured as described above, most of the damping force of the shock absorber is generated by the piston rod 9.
is transmitted to the vehicle body (as shown), but part of the damping force is
From the piston rod 9 via the rod screw 13,
It is transmitted to the sensor unit 3 and each piezo element 22 a -
Distort 22c.

The electric charge generated in each piezo element 22a to 22C is transferred to the electrode plate 24. Cards collected by a to 74 d Lead wire 36a
, 36b to an external signal processing circuit. In other words, since a plurality of piezo elements 22a to 22c are stacked, the overall output charge is doubled compared to when there are only one piezo element.

Furthermore, due to the distortion of the piezo elements 72a to 22c, the upper case 5 slides slightly 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). ．． Since it is sealed with O, outside air cannot enter the inside of the lower case 7.

As described above, in this embodiment, a plurality of piezo elements 2
Since '2a to 27c are stacked, sufficient charge can be output. Therefore, it is possible to obtain an electrical signal with a good S/N ratio.

In addition, a package structure is adopted in which the Senza Cornit 3 is housed in the upper case 5 and the lower case 7, and an O-ring 40 and bushes 4, 2a, 42b are installed.
Since the seal is completely sealed using a damping force detector for vehicles, it is possible to prevent condensation and foreign matter from entering even when the vehicle damping force detector is used in an atmosphere of high humidity or dust, preventing charge leakage and electrode plates. Accidents such as short circuits between the two 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 this embodiment, the rod screw 13 is used to tighten the sensor unit 3, but during this tightening, care is taken to prevent the lower case 7 from rotating relative to the upper case 5.
It may be fixed using a lock pin.

In addition, although the rod screw 13 and the upper case 5 are in surface contact 12, the contact surface of the upper case 5 is made convex and the contact surface of the rod screw 13 is finished concave to make the damping force more uniform. 22c.

Furthermore, metal dummies of the same shape are arranged outside the insulating disks 30a and 30b [2, the insulating disks 3 are
0a and 30bl may be designed to prevent concentration of stress and damage to each part of the sensor unit 3.

Next, in this embodiment, the sensor unit [3] is housed in the hollow part 11 of the piston rod 9, and the rod screw 1
3 (Second tightening (j) Although fixed, the sensor unit may be configured to be tightened directly by the upper case.

That is, as shown in FIG. 4, the outer periphery of the upper case 50 (two male threads 50a are cut square, the inner wall of the hollow part 60a of the piston rod 60 is cut with a female thread 60b, and a slit cut on the upper surface of the upper case 50 is cut. By applying a screwdriver (as shown) to 1-5ob and rotating the upper case 50, the sensor unit-q=0-62 is tightened and fixed. A lock pin 54 is provided to prevent the case 52 from rotating.A clamp 56 also connects the lead wires 56a and 56b to the lower case 5.
2 to compensate for the tensile strength of the lead wires 56a and 56b.

Furthermore, as shown in FIG. 5, a cylindrical hole 7 is provided at the center of the bottom of each of the upper case 70 and the lower case 2
0a and 72a, and a through hole 74a is also formed in the center of the rod screw 74, and an electric wire (not shown) is drawn in from the outside of the piston rod 76 to connect the sensor unit 8.
It may be configured so that it can be connected to 0. In this case, in addition to the already provided O-ring 82a, an O-ring 82b is also provided on the inner wall of the hole 72a of the lower housing 2, so that the sensor unit 80 can be housed airtightly. Further, in addition to the insulator 84a disposed on the outer periphery of the sensor unit 80, an insulator 84b is also disposed on the inner circumferential surface of the lower case 2 to achieve complete insulation.

[Effects of the Invention] As detailed above, according to the vehicle damping force detector of the present invention, the laminate is housed in an airtight container that prevents outside air from entering with a sealing member, so it is free from high humidity, dust, etc. The damping force can be detected accurately even when used in an atmosphere of

[Brief explanation of drawings]

Fig. 1 is a sectional view of a vehicle damping force detector, Fig. 2 is a perspective view of the sensor unit, Fig. 3 is a side view of the sensor unit,
FIG. 4 is a sectional view of another embodiment in which the upper case also serves as a rod screw, and FIG. 5 is a sectional view of another embodiment in which the lead wire can be drawn out to the outside of the rod.

Claims (1)

[Scope of Claims] A laminate in which a plurality of piezoelectric elements are stacked and provided with an electrode for synthesizing and outputting the output charge of each piezoelectric element, a box having an opening, and a box fitted in the opening. and a fitting body that closes the opening, and at least the box body or the fitting body is formed so as to be slidable in the fitting direction; A damping force detector for a vehicle, comprising: a seal member for keeping the inside of the airtight container airtight, and the laminate is housed in the airtight container.