JP2010078554A - Load detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load detector capable of improving sensitivity of an output signal as an elastic body is likely to flex against a load. <P>SOLUTION: The load detector includes a cylindrical elastic body 11 having strain sensor elements 16, 19 and 20 provided on an outer side face, a supporting member 24 for supporting double-ended openings 11a and 11b of the elastic body 11 and an annular pressurizing member 26 coming into contact with an inner side face of the elastic body 11. By applying a load to the pressurizing member 26 in a direction vertical to an axial center of the elastic body 11, shearing force is caused to act approximately at the center of the elastic body 11 having the double-ended openings 11a and 11b fixed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a load detection device for detecting various loads such as detection of depression load of vehicle pedals, detection of cable tension of a vehicle parking brake, detection of seating surface load of a vehicle seat, and the like. .

  This type of conventional load detection device is configured as shown in FIGS. 8 is a perspective view of a conventional load detection device, FIG. 9 is a development view of a strain generating body in the load detection device, and FIG. 10 is a circuit diagram of the load detection device.

  8 to 10, reference numeral 1 denotes a cylindrical strain generating body, and a pair of circumferential strain detecting elements 2 and a pair of width direction strain detecting elements 3 are fixed to the outer surface of the strain generating body 1. . Further, the circumferential strain detection element 2 and the width direction strain detection element 3, the power supply electrode 4, the GND electrode 5 and the output electrode 6 are electrically connected to the outer surface of the strain generating body 1 by a circuit pattern 7. Thus, a bridge circuit as shown in FIG. 9 is configured.

  In the conventional load detecting device configured as described above, when a compressive force acts on the cylindrical strain generating body 1 in a direction parallel to the axis C, the resistance value of the pair of width direction strain detecting elements 3 is as follows. As it decreases, the resistance value of the pair of circumferential strain sensing elements 2 increases. The pair of width direction strain sensing elements 3 and the pair of circumferential direction strain sensing elements 2 constitute a bridge circuit with the power supply electrode 4, the GND electrode 5, the output electrode 6 and the circuit pattern 7. An output signal is output from the output electrode 6 in accordance with the compressive force acting on 1.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP-A-6-207866

  However, in the conventional configuration described above, since the load acts in a direction parallel to the axis C of the strain generating body 1, the strain generating body 1 itself becomes a resistance to deformation against the load and There has been a problem that distortion is less likely to occur in the directional strain detection element 2 and the width direction strain detection element 3, thereby reducing the sensitivity of the output signal.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a load detection device in which a strain generating body is easily bent with respect to a load and the sensitivity of an output signal can be improved. .

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 of the present invention includes a cylindrical strain generating body provided with a strain sensing element on an outer surface, a support member that supports both ends of the strain generating body, and an inside of the strain generating body. A ring-shaped pressing member that contacts the side surface, and applying a load to the pressing member in a direction perpendicular to the axial center of the strain-generating body, so that both ends of the strain-generating body are fixed at substantially the center. According to this configuration, a load is applied to the pressing member in a direction perpendicular to the axial center of the strain-generating body, and the both-end openings are fixed. Since a shearing force is applied to the approximate center of the strained body, the strained body is more easily bent than the conventional strained body with a load applied in the axial direction. This makes it easier for distortion to occur in the strain sensing element, improving the sensitivity of the output signal. The person has an effect that it is.

  In the invention according to claim 2 of the present invention, in particular, the pressing member is fixed to the outer surface, a shaft penetrating the inside of the cylindrical strain body is provided, and both ends of the shaft are fixed. Therefore, according to this configuration, the pressing member is fixed to the outer surface, the shaft penetrating the inside of the cylindrical strain body is provided, and both ends of the shaft are fixed. The tilt of the shaft at the time is prevented, and this has the effect of improving the accuracy of load detection.

  The invention according to claim 3 of the present invention is particularly provided with a cylindrical sleeve that penetrates the inside of the strain generating body and has a pressing member on the outer surface, and further provides a shaft that is inserted into the inside of the sleeve, Further, both ends of the shaft are fixed. According to this configuration, a cylindrical sleeve that penetrates the inside of the strain generating body and has a pressing member on the outer surface is provided, and is further inserted into the sleeve. Since the shaft is provided and both ends of the shaft are fixed, even when the shaft moves in the thrust direction, the external force applied from the pressing member is the first opening in the strain generating body. This acts on the approximate center between the first opening and the second opening, thereby having the effect of stabilizing the output signal.

  As described above, the load detection device of the present invention includes a cylindrical strain generating body provided with a strain sensing element on the outer surface, a support member that supports the openings at both ends of the strain generating body, and the inside of the strain generating body. A ring-shaped pressing member that contacts the side surface, and applying a load to the pressing member in a direction perpendicular to the axial center of the strain-generating body, so that both ends of the strain-generating body are fixed at substantially the center. Since a shearing force is applied to the strain generating body, the strain generating body is more easily deflected than a conventional cylindrical strain generating body in which a load is applied in the axial direction. Since it becomes easy to generate | occur | produce distortion in a detection element, there exists an outstanding effect that the sensitivity of an output signal can be improved.

(Embodiment 1)
Hereinafter, the first and second aspects of the present invention will be described with reference to the drawings.

  1 is a perspective view of a load detection device according to Embodiment 1 of the present invention, FIG. 2 is a side sectional view of the load detection device, FIG. 3 is a side view of the load detection device, and FIG. It is an expanded view of a distortion body.

  1 to 4, reference numeral 11 denotes a cylindrical strain generating body. The strain generating body 11 has an axial center C installed in a horizontal direction, and a power electrode 12 made of a conductive material on the outer surface thereof. The first output electrode 13, the second output electrode 14, and the GND electrode 15 are provided in a state where they are located in the vicinity of each other. In addition, a first strain sensing element 16 made of a strain resistance element is provided on the outer surface of the strain generating body 11 and at substantially the center of the first opening 11a and the second opening 11b, and The first strain sensing element 16 has one end electrically connected to the power supply electrode 12 by a circuit pattern 17 and the other end connected to the second output electrode 14. In addition, a second end made of a strain resistance element is located on the outer surface of the strain body 11 on the first opening 11a side of the strain body 11 with respect to the first strain sensing element 16. A strain sensing element 18 is provided, and the second strain sensing element 18 is electrically connected at one end to the power supply electrode 12 by a circuit pattern 17 and electrically connected at the other end to the first output electrode 13. Connected to. Further, a third strain sensing element 19 made of a strain resistance element is provided on the outer surface of the strain generating body 11 and is located closer to the second opening 11 b than the first strain sensing element 16. The third strain sensing element 19 has one end electrically connected to the first strain sensing element 16 and the second output electrode 14 by the circuit pattern 17 and the other end electrically connected to the GND electrode 15. Connected to. In addition, in the outer surface of the strain-generating body 11, a fourth opening made of a strain resistance element substantially parallel to the first strain sensing element 16 is provided at the approximate center of the first opening 11a and the second opening 11b. The strain detection element 20 is provided, and one end of the fourth strain detection element 20 is electrically connected to the second strain detection element 18 and the first output electrode 13 by a circuit pattern 17. . The fourth strain sensing element 20 constitutes a full bridge circuit by electrically connecting the other end to the GND electrode 15.

  Reference numeral 21 denotes a first support member made of, for example, SUS430. The first support member 21 supports the first opening 11a of the strain body 11 by welding and is provided with an attachment hole 22. Reference numeral 23 denotes a cylindrical second support member made of, for example, SUS430, and the second support member 23 integrally forms a support member 24 by welding with the first support member 21, and the second support member 23. A male screw 25 is provided on the outer surface of the member 23. The second support member 23 supports the second opening 11b in the strain body 11 by welding. Reference numeral 26 denotes a pressing member made of a ring-shaped SUS430, and the outer surface of the pressing member 26 is an inner surface located between the first opening 11a and the second opening 11b in the strain body 11 over the entire circumference. It is in contact with the approximate center.

  Reference numeral 27 denotes a circuit board made of a polyimide film. The circuit board 27 is electrically connected to the power supply electrode 12, the first output electrode 13, the second output electrode 14, and the GND electrode 15 in the strain generating body 11. . 28 is a resin connector, and this connector 28 is provided with a protrusion 29, and this protrusion 29 is inserted into the mounting hole 22 in the first support member 21 and fixed. The connector 28 is provided with four connector terminals 30, and the connector terminals 30 are electrically connected to the circuit board 27. Reference numeral 31 denotes a shaft. The shaft 31 fixes the ring-shaped pressing member 26 to the outer surface, and penetrates the inner side of the strain body 11.

  Next, a method for assembling the load detection device according to Embodiment 1 of the present invention configured as described above will be described.

  First, a glass paste (not shown) is printed on the outer surface of a cylindrical seamless stainless tube (not shown) having a thickness of about 1 mm, which is a material of the strain body 11, and then at about 850 ° C. for about 10 minutes. Bake.

  Next, a conductive paste (not shown) containing silver as a main component is printed on the outer surface of the stainless steel tube and baked at about 850 ° C. for about 10 minutes. The electrode 12, the first output electrode 13, the second output electrode 14, the GND electrode 15 and the circuit pattern 17 are formed.

  Next, after printing a metal glaze resistance paste (not shown) on the outer surface of the stainless steel tube, it is dried at about 130 ° C. for about 10 minutes, and then the stainless steel tube is baked at about 850 ° C. for about 10 minutes. As a result, the third strain sensing element 19, the fourth strain sensing element 20, the first strain sensing element 16, and the second strain sensing element 18 are formed. Thereby, the stainless steel tube is manufactured as the strain body 11.

  Next, the contact portion (not shown) between the first opening 11 a and the first support member 21 in the strain body 11 is irradiated with a laser so that the strain body 11 is subjected to the first support member 21. To fix.

  Next, the second opening 11b in the strain body 11 and a contact portion (not shown) between the second support member 23 are irradiated with a laser so that the strain body 11 is subjected to the second support member. At the same time as fixing 23, the first support member 21 and the second support member 23 are irradiated by irradiating a laser (not shown) between the first support member 21 and the second support member 23. Are fixed to each other to form the support member 24.

  Next, a connector 28 in which the connector terminal 30 is integrally formed is prepared in advance, and the circuit board 27 is fixed to the connector 28 with an adhesive, and then one end of the circuit board 27 is soldered to the connector terminal 30. The other end of the circuit board 27 is soldered to the power supply electrode 12, the first output electrode 13, the second output electrode 14, and the GND electrode 15 in the strain body 11.

  Finally, the pressing member 26 is attached to the inner side surface of the strain body 11.

  Next, the operation of the load detection device according to the first embodiment of the present invention configured and assembled as described above will be described.

  First, as shown in FIG. 5, after the first support member 21 is brought into contact with the counterpart mounting member 32, the female screw 34 (not shown) in the nut 33 is replaced with the male screw 25 (see FIG. The load detecting device is fixed to the mating attachment member 32 by screwing to the other mounting member 32.

  Next, the shaft 31 is inserted into the hole 36 in the shaft support member 35, and the shaft 31 is press-fitted into the inner surface of the pressing member 26.

  In this state, for example, when a load of a pedal for a vehicle acts on the shaft support member 35 in a direction perpendicular to the axial direction of the strain body 11 in the load detection device, as shown in FIG. A strain is generated in the shearing body 11 in the shearing direction by applying a shearing force to the approximate center of the first opening 11a and the second opening 11b on the inner surface of the straining body 11, and the first strain is generated. A tensile stress is generated in the detection element 16 and the fourth strain detection element 20, and a compressive stress is generated in the second strain detection element 18 and the third strain detection element 19. Therefore, the resistance values of the first strain sensing element 16 and the fourth strain sensing element 20 are increased, while the resistance values of the second strain sensing element 18 and the third strain sensing element 19 are decreased. Therefore, a voltage is applied to the power supply electrode 12, the GND electrode 15 is grounded, the differential voltage between the first output electrode 13 and the second output electrode 14 is measured, and the difference is determined from a previously obtained relationship. The load applied to the strain generating body 11 can be measured based on the dynamic voltage. Note that FIG. 6 shows the strain of the strain generating body 11 extremely large for easy understanding.

  That is, by applying a load in a direction perpendicular to the axial center of the strain-generating body 11 to the ring-shaped pressing member 26 that contacts the inner surface of the strain-generating body 11, the first opening 11a and the second opening Since a shearing force is applied to substantially the center of the strain generating body 11 to which the portion 11b is fixed, a load is applied to the cylindrical strain generating body 11 in the axial direction as in the prior art. In comparison, the strain-generating body 11 is easily bent, and as a result, distortion occurs in the first strain sensing element 16, the second strain sensing element 18, the third strain sensing element 19, and the fourth strain sensing element 20. Since it becomes easy, the effect that the sensitivity of an output signal can be improved is acquired.

  In the first embodiment of the present invention, the pressing member 26 is fixed to the outer surface, the shaft 31 penetrating the inside of the cylindrical strain body 11 is provided, and both ends of the shaft 31 are fixed. As a result, the inclination of the shaft 31 at the time of load application is prevented, thereby obtaining the effect that the accuracy of load detection can be increased.

  In the load detection device according to the first embodiment of the present invention, the first strain sensing element 16, the second strain sensing element 18, the third strain sensing element 19, and the first strain sensing element 11 are formed on the outer surface of the strain generating body 11. 4, the first strain sensing element 16, the second strain sensing element 18, the third strain sensing element 19, and the fourth strain are provided on the inner surface of the strain generating body 11. Even when the detection element 20 is provided, the same effects as those of the first embodiment of the present invention can be obtained.

  In the load detection device according to the first embodiment of the present invention, the first strain sensing element 16, the second strain sensing element 18, the third strain sensing element 19, and the fourth strain sensing element 20 are fully used. Although a bridge circuit is configured, a half bridge circuit may be used.

  In the load detection device according to the first embodiment of the present invention, the first strain sensing element 16, the second strain sensing element 18, the third strain sensing element 19 and the fourth strain are caused by thick film resistance. Although what comprised the sensing element 20 was demonstrated, the 1st strain sensing element 16, the 2nd strain sensing element 18, the 3rd strain sensing element 19 and 4th using thin film resistance, a piezoelectric element, a piezoelectric element, etc. Even when the strain sensing element 20 is configured, the same effects as those of the first embodiment of the present invention can be obtained.

(Embodiment 2)
Hereinafter, the second aspect of the present invention will be described with reference to the drawings.

  FIG. 7 is a side sectional view of the load detection device according to Embodiment 2 of the present invention. In the second embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the load detection device according to the first embodiment of the present invention described above, the pressing member 26 is directly provided on the outer surface of the shaft 31, but the strain detection device according to the second embodiment of the present invention is the first one. A cylindrical sleeve 38 penetrating the inside of the cylindrical strain body 11 is integrally provided on the support member 37, and a pressing member 39 is provided on the outer surface of the cylindrical sleeve 38, and the cylindrical sleeve is provided. A shaft 31 (not shown) is inserted inside 38. In this state, when a load acts on the shaft support member 35 (not shown) in a direction perpendicular to the axial direction of the strain body 11 in the load detection device, the load is applied via the sleeve 38 of the first support member 37. A shearing force acts on substantially the center of the first opening portion 11a and the second opening portion 11b on the inner surface of the strain-generating body 11 supported at both ends, and the strain-generating body 11 is distorted in the shearing direction. Therefore, also in the second embodiment of the present invention, the load applied to the strain generating body 11 can be detected in the same manner as the load detection device in the first embodiment of the present invention described above.

  Here, considering the case of attachment to the counterpart attachment member, in the load detection device according to Embodiment 2 of the present invention, as shown in FIG. A cylindrical sleeve 38 penetrating the inside is integrally provided, and a shaft (not shown) separate from the first support member 37 inserted into the sleeve 38 is further provided. (Not shown) is fixed at both ends, so that even when the shaft moves in the thrust direction, the external force applied from the pressing member 39 is the same as that of the first opening 11a in the strain body 11 and the first force. It acts on the approximate center of the two opening portions 11b, thereby obtaining the effect that the output signal is stabilized.

  The load detection device according to the present invention has an effect that the strain generating body is easily bent with respect to the load, and the sensitivity of the output signal can be improved. This is useful in a load detection device for detecting various loads, such as detection, detection of cable tension of a parking brake for a vehicle, detection of a seating surface load of a vehicle seat.

The perspective view of the load detection apparatus in Embodiment 1 of this invention Side sectional view of the load detector Side view of the load detector Development view of strain-generating body in the load detector Side sectional view showing a state in which the load detection device is attached to the counterpart attachment member The figure which shows the operation state of the load detection device Side sectional view of the load detection device according to Embodiment 2 of the present invention. A perspective view of a conventional load detection device Development view of conventional load detector Circuit diagram of conventional load detector

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Strain body 11a 1st opening part 11b 2nd opening part 16 1st strain sensing element 18 2nd strain sensing element 19 3rd strain sensing element 20 4th strain sensing element 24, 37 Support member 26 39 Pressing member 31 Shaft 38 Sleeve

Claims (3)

A cylindrical strain body provided with a strain sensing element on the outer surface, a support member that supports openings at both ends of the strain body, and a ring-shaped pressing member that abuts against the inner surface of the strain body. The load detecting device is configured to apply a load to the pressing member in a direction perpendicular to the axis of the strain generating body so that a shearing force is applied to the substantially center of the strain generating body having the openings at both ends fixed. . The load detecting device according to claim 1, wherein the pressing member is fixed to the outer surface, a shaft penetrating the inside of the cylindrical strain body is provided, and both ends of the shaft are fixed. The cylindrical sleeve which penetrates the inner side of a strain body and has a pressing member in the outer surface is provided, Furthermore, the axis | shaft penetrated inside this sleeve is provided, and the both ends of this axis | shaft are fixed. The load detection apparatus described.

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