JP2018136196A - Load sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load sensor which can be manufactured by a smaller number of manufacturing steps by separately forming a flange as a load receiver and a circuit container housing circuits and joining the flange and the circuit container to each other.SOLUTION: A flange 5 having a flange recess part 5a with a screw structure and a circuit container 24 having a circuit container protrusion part 24a with the screw structure are separately formed and are screwed to each other.SELECTED DRAWING: Figure 1B

Description

  The present invention detects a strain of a member that is distorted according to a load (pushing force, thrust) of a measurement object with a strain gauge, converts this into an electrical signal, and measures a load applied to the measurement object. About.

  Conventionally, a strain body 20 attached to a measurement object and a flat sensor plate 1 connected to the strain body 20 are provided, and strain is measured by a strain gauge 22 mounted on the sensor plate 1. A load sensor that outputs a signal to the outside is known. In this conventional load sensor, for example, as shown in Patent Document 1, the strain body 20 is formed of a thick plate material, and the periphery thereof is formed in a rectangular shape. On the upper surface of the strain generating body 20, a recess 21 is formed which is recessed toward the lower surface side at a position entering the inner side from the periphery. The sensor plate 1 is a member in which a thin plate material is formed in a rectangular shape. The sensor plate 1 is disposed on the upper surface of the strain body 20 so as to cross the recess 21 of the strain body 20, and both ends 1 a and 1 a in the major axis direction are fixed to the edge portion 21 a of the recess 21 by welding. And joined to the strain body 20. Further, the sensor plate 1 includes a transmission unit 7 that transmits the displacement of the strain gauge 22 and the strain generating body 20 to the sensor plate 1.

Japanese Patent Application No. 2006-529156

  However, the conventional load sensor represented by Patent Document 1 has the following improvements.

  It is generally known that when outputting a signal measured by a strain sensor to the outside, a circuit is required for the purpose of noise prevention, improvement of static electricity resistance, measures against instantaneous interruption of the circuit due to contact with a connector, etc. However, there is no description about a circuit storage portion for storing this circuit. Moreover, when installing a circuit storage part in a thick strain body, in order to ensure the storage area, it is necessary to make thin the wall thickness which covers a side surface and an upper surface. Cutting out a thick strain body and a thin circuit housing portion from a single piece of metal is wasteful in material, and it takes time for processing and leaves room for improvement.

  In order to solve the above-mentioned problems, in the load sensor according to the present invention, the strain generating body is cut out from a block material such as a cylinder, and the circuit storage portion is cut out from the pipe material to reduce the number of processing steps. Further, the strain generating body and the circuit housing portion are configured to be joined by a method such as a screw structure, press-fitting, welding, or adhesion.

  According to the present invention, by separately processing and joining the strain generating body and the circuit housing portion, it is possible to eliminate the waste of materials and reduce the processing time.

It is a load sensor concerning Example 1 of the present invention. It is sectional drawing seen from the arrow direction of the sectional line shown by AA of FIG. 1A. It is a figure which shows before and after joining of the flange of FIG. 1A and a circuit storage part. 1A is a view of the sensor plate and the strain IC as seen from the direction of the arrow indicated by D in FIG. It is a perspective view of a PWB guide and PWB ASSY. It is a block diagram of distortion IC. It is a schematic circuit diagram of distortion IC. It is sectional drawing of the conventional load sensor. It is a figure which shows before and after joining of the flange concerning Example 2 of this invention and a circuit accommodating part.

  Hereinafter, embodiments of the load sensor of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the description of the examples described below unless it exceeds the gist.

[Example 1]
A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the flange 5 and the circuit housing portion 24 are provided with a flange recessed portion 5a and a circuit housing portion protruding portion 24a, and the flange 5 and the circuit housing portion 24 are joined by a screw structure.

  The load sensor 100 includes a disk-shaped sensor plate 1, two strain ICs 4 a and 4 b attached to the sensor plate 1, a circuit housing portion 24 that holds the periphery of the sensor plate 1, and a flange 5 that receives a load 90. And a cover 8, a PWB (Printed Wiring Board) ASSY 31a, b, and a PWB guide 29 which is a circuit plate on which the PWB ASSY 31a, b is mounted.

  The flange 5 has a positioning pin 2 and plays a role of positioning in the rotational direction with respect to the shaft 91. The flange 5 and the circuit housing portion 24 are joined by forming screws on the flange recessed portion 5a and the circuit housing portion projecting portion 24a. The outer periphery of the sensor plate 1 is fixed to the circuit storage unit 24. The flange 5 has a transmission part 7 joined to the central part 1 b of the sensor plate 1. The transmission unit 7 has a role of transmitting the displacement when the flange 5 receives the load 90 to the sensor plate 1. The shaft 92 contacts the flange 5 and applies a load 90 to the flange 5.

  With such a configuration, when the shaft 92 contacts the flange 5 and applies a load, the displacement causes the sensor plate 1 to be deformed through the transmission portion 7. The strain ICs 4a and 4b detect the strain generated in the sensor plate 1.

  Further, the PWB guide 29 is not directly mounted on the sensor plate 1 but is mounted on the circuit housing portion 24. Therefore, since the deformation of the sensor plate 1 is not directly transmitted to the PWB guide 29, damage to PWBASSY provided in the PWB guide can be suppressed.

  As shown in FIG. 3, two strain ICs 4 a and 4 b are mounted on the sensor plate 1. The strain ICs 4a and 4b are joined to the sensor plate 1 with glass 30a and 30b. The sensor plate 1 has semicircular punched portions 9a and 9b. As a result, the mounting portion on which the strain ICs 4a and 4b of the sensor plate 1 are mounted is substantially rectangular. By making the sensor mounting portion a substantially rectangular XY direction anisotropic shape, it becomes possible to generate a strain difference in the XY direction with respect to the load from the transmission unit 7. The cut-out portions 9a and 9b are formed except for the flange connection portion.

  The sensor plate 1 has an outer periphery fixed to the circuit housing portion 24. A central portion 1b of the sensor plate 1 is connected to a transmission portion 7 provided on a flange. The strain ICs 4a and 4b are arranged on both sides of the center portion 1b of the sensor plate. By arranging in this way, failure diagnosis is possible by comparing the outputs of the two strain ICs 4a and 4b.

  FIG. 4 is a perspective view of the PWB guide 29 and the PWB ASSY 31a and 31b.

  PWB ASSY 31a and PWB ASSY 31b have the same structure. The PWB guide 29 is mounted with PWB ASSY 31a and 31b. PWB ASSY 31 a and PWB ASSY 31 b are arranged symmetrically with respect to the center of the PWB guide 29.

  The PWB guide 29 is fixed to the circuit storage unit 24. The PWB ASSY 31 a and 31 b are fixed to the PWB guide 29 with an adhesive 33. The PWB ASSY 31 a and 31 b are positioned by the convex portions 34 a to 34 e of the PWB guide 29.

  The PWB ASSY 31a and the strain IC 4a, and the PWB ASSY 31b and the strain IC 4b are electrically connected by an aluminum wire bonding (hereinafter abbreviated as aluminum W / B) 35.

  The PWB ASSY 31a is an integrated product (ASSY) including a PWB 32, a connector 36 mounted on the PWB 32, a protective resistor 38, and a capacitor 37. The capacitor 37 plays a role of noise prevention and power supply / output stabilization, and the protective resistor 38 plays a role of signal protection. The connector 36, the capacitor 37, and the protective resistor 38 are connected to the PWB 32 with solder 39 (not shown). The strain IC 4a and the PWB 32 are connected to the power source, GND, and output by aluminum W / B as an output 35a. The strain IC 4b and the PWB 32 are connected to four communication lines by aluminum W / B as a communication 35b.

  The PWB ASSY 31a is an integrated product (ASSY) including a PWB 32, a connector 36 mounted on the PWB 32, a protective resistor 38, and a capacitor 37. The strain IC 4a and the PWB 32 are connected to the power source, GND, and output by aluminum W / B as an output 35a. The strain IC 4b and the PWB 32 are connected to four communication lines by aluminum W / B as a communication 35b.

  On the other hand, the PWB ASSY 31b on the opposite side (not shown) of the cross section is connected to the power source, GND, and output 35b from the strain IC 4b to the aluminum W / B output 35b, and from the strain IC 4a to the aluminum W / B communication. For communication 35a, four communication lines are connected.

  By adopting such a configuration, the aluminum W / B 35 is connected to the strained IC 4 in the shortest time, noise prevention and vibration resistance are improved, and the layout of the aluminum W / B 35 is concisely summarized. The size of the load sensor 100 is reduced.

  The distortion IC will be described with reference to FIGS.

  The strain IC 4 includes a bridge circuit 11 composed of four strain gauges 10a to 10d, an amplifier 12 that amplifies the output of the bridge circuit 11, an output adjustment logic 13 for the strain, a temperature characteristic error correction logic 14, a temperature sensor 15, and the like. ing. The bridge circuit 11 detects the strain of the sensor plate 1 to be installed, and the output adjustment logic 13 sets the output according to a desired load, that is, the strain generated in the sensor plate. The temperature correction logic 14 and the thermometer 15 It is possible to correct a temperature characteristic error of itself or a constituent member such as the sensor plate 1.

  As described above, by installing a circuit storage unit, when outputting the signal measured by the strain sensor to the outside, it can be used to prevent noise, improve electrostatic resistance, and take measures against instantaneous circuit breakage caused by contact with connectors, etc. Possible circuit can be stored.

  In this embodiment, the flange 5 that is a strain generating body and the circuit housing portion are manufactured separately, and are joined to each other, thereby eliminating waste of materials and reducing processing time. It is possible to provide a load sensor.

  Furthermore, by providing output adjustment logic, temperature correction logic, a thermometer, etc. to the strain IC, correction by the strain IC can be performed, so that the assembly error of the load sensor can be canceled by the output adjustment, the sensor plate, the flange, the distortion inside the strain IC. The temperature characteristics of the gauge can be corrected.

  In addition, the distortion IC correction function can reduce variations in assembly and variations in characteristics, so that it is not necessary to prepare a circuit for correcting output separately in addition to improving the yield. As a result, cost can be reduced.

[Example 2]
FIG. 8 is a cross-sectional view showing the flange 5 and the circuit storage portion 24 according to the second embodiment of the present invention. The description of the same configuration as in the first embodiment is omitted.

  The circuit housing 24 and the sensor plate 1 are integrally formed by a sintering method. After filling the concave portion 5b of the flange 5 with the adhesive 6, the convex portion 24b of the circuit housing portion is inserted, and the adhesive is cured and joined. Similar to the first embodiment, the number of processing steps can be reduced.

  Note that, as an example, the description has been made with the configuration in which the strain IC is arranged on the sensor plate. However, the strain IC may be arranged directly around the transmission portion 7 of the flange 5 and configured without the sensor plate. The load sensor has been described above. However, when the load and the displacement in the load direction correspond to 1: 1, the load sensor may be applied as a displacement sensor.

DESCRIPTION OF SYMBOLS 1 Sensor plate 1a Sensor plate both ends 1b Sensor plate center part 1e Sensor plate junction part 2 Positioning pin 4a-4c Strain IC
5 Flange 5a Flange recess (with screw)
5b Flange recess (without screw)
6 Adhesive 7 Transmission part 8 Cover 9a-9c Semicircular extraction part 10a-10d Strain gauge 11 Bridge circuit 12 Amplifier 13 Output adjustment logic 14 Temperature correction logic 15 Thermometer 16 A / D (Analog / digital conversion)
17 D / A (digital analog conversion)
DESCRIPTION OF SYMBOLS 20 Strain body 21 Recess 21a Recess edge 22 Strain gauge 23 Load sensor receiving surface 24 Circuit storage part 24a Circuit storage part convex part (with screw)
24b Convex part of circuit storage part
29 PWB guide 30a, 30b Glass 31a, 31b PWB ASSY
32 PWB
33 Adhesive 34a-34d Convex part 35a Aluminum W / B (aluminum wire bonding) 3 for output 35b Aluminum W / B (aluminum wire bonding) 4 for communication 36 Connector 37 Capacitor 38 Protection resistance 39 Solder 90 Load (or thrust) )
91 Load application shaft 92 Shaft 100 Load sensor

Claims (8)

In a load sensor comprising a flange having a load receiving surface, a sensor element, and a circuit board to which a signal from the sensor element is input,
The sensor element is affixed to a sensor plate;
A circuit accommodating portion for excluding the sensor plate and the circuit board,
The flange and the circuit housing part are processed products processed separately, and the flange and the circuit housing part are joined to each other.   The load sensor according to claim 1, wherein a transmission portion that contacts the sensor plate is formed on the flange. A circuit plate for mounting the circuit board;
The load sensor according to claim 2, wherein the circuit plate is mounted on the circuit housing portion. A second sensor element affixed to the sensor plate;
A second circuit board mounted on the circuit plate,
The sensor element is connected to the output pad of the circuit board and the communication pad of the second circuit board by W / B, respectively.
The load sensor according to claim 3, wherein the second sensor element is connected to a communication pad of the circuit board and an output pad of the second circuit board by W / B, respectively.   The load sensor according to claim 4, wherein the circuit housing portion and the sensor plate are joined by screws.   The load sensor manufacturing method according to claim 4, wherein the circuit housing portion and the pressure receiving frame are joined by a sintering method or a metal powder injection molding method.   The load sensor according to claim 4, wherein the flange and the circuit housing portion are joined by any one of a screw, press-fitting, an adhesive, and welding.   The first and second sensor elements are composed of a bridge circuit composed of a plurality of strain gauges, an output adjustment logic, a temperature correction logic, a thermometer, or an IC including all, and an output. The load sensor according to claim 4, wherein adjustment or temperature correction is possible.

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