JPH0612934U - Load detector - Google Patents

Abstract

(57) [Summary] [Purpose] To accurately detect an input load over a wide range.
Reduce manufacturing costs. [Structure] Movable member 5 having rod 5b for load input
Is housed in the casing 1 so that it can be moved up and down. The movable member 5,
The casing 1 is supported via the first coil spring 6 and the second coil spring 7. A plus electrode 9 and a minus electrode 11 are attached to the casing 1 and the movable member 5 so that the electrostatic capacitance between the electrodes 9 and 11 changes according to the relative position of the casing 1 and the movable member 5. Substrate 1
Detected by the electric circuit above 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a load detecting device used for detecting an input load of each part of an automobile.

[0002]

[Prior art]

 In this type of load detection device, a beam member that can be flexibly deformed is provided on the detected member, and a strain gauge is attached to this beam member so that the resistance of the strain gauge that changes according to the flexural deformation of the beam member. A device that detects the input load by measuring the value has been used conventionally.

This technique is disclosed in Japanese Patent Laid-Open No. 55-52924.

[0004]

[Problems to be solved by the device]

 However, in the case of the conventional load detection device described above, since the input load is detected by utilizing the bending deformation of the beam member and the resistance value change of the strain gauge, when a large load is input to the detected member, The beam member may be plastically deformed and its characteristics may be changed, or the strain gauge may be destroyed. For this reason, the input load detection range was narrow and limited.

Further, in the above load detecting device, in order to secure the bending of the beam member that accurately corresponds to the input load, the beam member must be processed in a complicated and highly accurate manner, and the manufacturing cost is reduced. There is also the problem of being bulky.

Therefore, the present invention is intended to provide a load detection device capable of accurately detecting an input load over a wide range and capable of being manufactured at low cost.

[0007]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention solves the above-mentioned problems by providing a movable member having a load input portion, a casing that houses the movable member, a coil spring that supports the movable member on the casing, the movable member and the casing. The electrode unit that changes the electrostatic capacity according to the relative position of the electrode unit and the electrostatic capacitance detection unit that detects the electrostatic capacitance of the electrode unit are used.

[0008]

[Action]

 When a load is input to the load input unit, the movable member deforms the coil spring and the relative position with respect to the casing changes. At this time, since the amount of deformation of the coil spring is proportional to the input load, the relative position between the movable member and the casing also corresponds to the input load. Then, the relative position between the movable member and the casing, which is changed by the input of the load, is detected by the electrostatic capacitance detection means as a change in the electrostatic capacitance of the electrode unit.

[0009]

【Example】

 Next, an embodiment of the present invention will be described with reference to FIGS.

In the drawings, reference numeral 1 denotes a casing. The casing 1 includes a case main body 2 having upper and lower concave portions 2 a and 2 b, and an upper portion that closes openings of the concave portions 2 a and 2 b of the case main body 2. It is composed of a cover 3 and a lower cover 4. Reference numeral 5 denotes a movable member slidably fitted in the upper concave portion 2a of the case main body 2, and the movable member 5 is arranged above the first coil spring 6 arranged on the lower side thereof. It is elastically supported by the case body 2 and the upper cover 3 by the arranged second coil spring 7. The movable member 5 is composed of a substantially disk-shaped main body 5a and a rod 5b as a load input portion which is fitted and fixed to the center of the upper surface of the main body 5a. The tip of the rod 5b penetrates the upper cover 3. And projects above the casing 1. The movable member 5 appropriately compresses and deforms the first coil spring 6 and the second coil spring 7 in accordance with the input load applied to the rod 5b, thereby displacing in the vertical direction.

Reference numeral 9 is a plus electrode attached to the bottom surface of the concave portion 2 a of the case body 2 via an insulating member 10, and 11 is attached to the lower surface of the movable member 5 via an insulating member 12. It is a negative electrode. The terminals 13 and 14 of these electrodes 9 and 11 penetrate the bottom surface of the case body 2 in the vertical direction and are soldered to the substrate 15 installed in the concave portion 2b on the lower side. Here, the tip of the positive side terminal 13 is integrally embedded in the positive electrode 9, but the tip of the negative side terminal 14 is formed in a wavy shape. Is slidably inserted in the groove 16 formed in the negative electrode 11. Therefore, even if the movable member 5 is displaced in the vertical direction, the minus electrode 11 is always electrically connected to the terminal 14 regardless of this displacement.

Further, the plus electrode 9 and the minus electrode 11 are arranged so as to face each other, and the dielectrics 17 and 18 having a large relative dielectric constant such as barium titanate are respectively provided on the respective facing surfaces. It is glued. Each of the dielectrics 17 and 18 is formed with a substantially T-shaped groove 17a and 18a as shown in FIG. 3, and each of the grooves 17a and 18a has a substantially H-shaped cross section. It is slidably fitted to the member 19. The guide member 19 is for keeping the distance between the two dielectrics 17 and 18 and the relative angle always constant, and the base portion thereof is fitted and fixed to the case body 2. In this embodiment, the positive electrode 9, the negative electrode 11, the terminals 13 and 14, and the dielectrics 17 and 18 constitute an electrode unit, and the electrode unit is located at the relative position between the movable member 5 and the casing 1. Accordingly, the capacitance between the electrodes 9 and 11 is changed.

Further, an electric circuit that constitutes electrostatic capacitance detecting means is incorporated in the substrate 15, and the electrostatic capacitance between the electrodes 9 and 11 is detected through this circuit, and the detection signal thereof is detected. Is output to the outside through the harness 20.

In the figure, 21 and 22 are seal members for sealing the rod 8 and the upper cover 3, 23 is a seal guide for holding the seal member 22, and 24 is a space between the upper cover 3 and the case body 2. The seal ring 25 that seals is a hemispherical head screwed to the tip of the rod 5b when detecting a compressive load.

In the above configuration, when detecting the compressive load of the detected member, the head 25 is screwed to the tip of the rod 5b as shown in FIG. 1, and the head 25 is brought into contact with the detected member. Let When a compressive load is input to the detected member in this state, this load is input to the movable member 5, and the movable member 5 compresses and deforms the first coil spring 6 to displace it downward. Here, since the amount of compressive deformation of the first coil spring 6 is proportional to the input load, the relative position of the movable member 5 and the casing 1 depends on the input load. When the movable member 5 is displaced downwards in this way, the area of the overlapping portion (of the dielectrics 17 and 18) of the positive electrode 9 and the negative electrode 11 increases in accordance with the displacement, and the area between the electrodes 9 1 Increases the capacitance of. This change in capacitance is output to the outside as a detection signal through a circuit on the substrate 15.

When detecting the tensile load of the detected member, the head 25 is removed from the tip of the rod 5b, and the rod 5b and the detected member are connected to each other via a jig (not shown). When a tensile load is input to the detected member in this state, this load is input to the movable member 5, and the movable member 5 is compressed and deformed by the second coil spring 7 and displaced upward. Here, since the amount of compressive deformation of the second coil spring 7 is proportional to the input load as in the case of the first coil spring 6, the relative position between the movable member 5 and the casing 1 depends on the input load. When the movable member 5 is displaced upward in this manner, the area of the overlapping portion (of the dielectrics 17 and 18) of the plus electrode 9 and the minus electrode 11 is reduced, and the electrostatic capacitance between the electrodes 9 and 11 is reduced. The change in capacitance is output as a detection signal to the outside through a circuit on the substrate 15.

FIG. 4 shows the relationship between the input load and the output voltage. As is clear from the figure, the output voltage increases and decreases in direct proportion to the increase and decrease of the input load.

As described above, this load detecting device converts the input load into a change in the relative position of the movable member 5 and the casing 1 by the action of the first coil spring 6 and the second coil spring 7, and the relative position is changed. Change is detected as a change in capacitance between the electrodes 9 and 11 in a non-contact manner, so a mechanical load that causes deterioration of each component is less likely to be applied, and durability against a large load input is obtained. Extremely high. In particular, the first and second coil springs 6 and 7, which support the input load, maintain their resilience even when the displacement limit (contact length) is reached, so even if an unexpectedly large load is input, it can be detected. There is no worry about going crazy. Further, in the case of this load detecting device, the detection accuracy can be easily increased by setting the strokes of the first and second coil springs 6 and 7 to be large, so that the detection accuracy is improved and the manufacturing cost is reduced. It is possible.

[0019]

[Effect of device]

 As described above, according to the present invention, the load input to the movable member is converted into the change in the relative position between the movable member and the casing by the coil spring, and the change in the position of the both is changed to the electrode unit and the capacitance detecting means. Since it is detected as a change in capacitance by means of, the large mechanical load that would damage the component parts will not be applied even if the input load increases. As a result, the durability of the device is improved and the input load can be accurately detected over a wide range.

Further, since the relative displacement of the movable member and the casing with respect to the input load can be easily increased by setting the coil spring, it is possible to detect the load with high accuracy even though the structure is relatively simple. Therefore, when the present invention is adopted, the manufacturing cost can be reduced without lowering the detection accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of part B in FIG.

FIG. 3 is an enlarged view of FIG.

FIG. 4 is a graph showing an input load-output voltage characteristic of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Casing, 5 ... Movable member, 5b ... Rod (load input part) 6 ... 1st coil spring, 7 ... 2nd coil spring, 9 ... Positive electrode (electrode unit), 11 ... Minus electrode (electrode unit), 13 , 14 ... Terminal (electrode unit), 15 ... Substrate (capacitance detecting means), 17, 18 ... Dielectric (electrode unit).

Claims (1)

[Scope of utility model registration request] 1. A movable member having a load input section, a casing for accommodating the movable member, a coil spring for supporting the movable member on the casing, and a capacitance according to a relative position between the movable member and the casing. A load detecting device comprising: an electrode unit for changing the electric field and an electrostatic capacity detecting means for detecting the electrostatic capacity of the electrode unit.