JP2008191093A - Strain gauge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a strain gauge capable of inhibiting generation of thermal electromotive force due to the Seebeck effect. <P>SOLUTION: In the strain gauge 1, a strain gauge body 11 is included, which is formed with the metal of a first kind and has two connecting terminals 11A and 11B. To each of two connecting terminals 11A and 11B, one connecting terminal of a first two lead wires 12A and 12B formed with metal of identical kind with the first kind of the metal is connected to elongate, respectively. The two other terminals of the first two lead wires 12A and 12B are connected on a relay terminal 100. For this relay terminal 100, since, while forcing heat-transfer between 12A1 and 12B1 to the two other terminals, function of thermal insulation is given from the periphery, except the two other terminals 12A1 and 12B1, generation of thermal electromotive force due to the Seebeck effect is restrained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a strain gauge for detecting strain.

  Conventionally, strain gauges for detecting strain are known (see Patent Document 1 to Patent Document 3). The strain gauges as shown in these patent documents are a base metal whose cross-sectional area is reduced and length is increased due to the elongation of the base metal that changes together when the base metal is affixed to the object to be measured. This resistance value is notified to the outside as distortion. Since the strain gauge is also used for measuring thermal stress, a base metal having a small temperature coefficient of electrical resistance such as constantan is used.

By the way, Constantan used as a base metal of a strain gauge is known to be a metal material used as one metal of a thermocouple. For this reason, in order to connect the strain gauge to an external measuring instrument, the constantan was pulled out to the relay terminal as a lead wire, and a lead wire made of another metal material was connected at the relay terminal to connect the measuring instrument to the strain gauge. Sometimes, a thermoelectromotive force is generated by the Seebeck effect, and an error is given to the measured value measured by the measuring instrument.
Japanese Patent No. 3596565 Japanese Patent No. 2992857 JP-A-6-34310

  An object of this invention is to provide the strain gauge which can suppress generation | occurrence | production of the thermoelectromotive force by a Seebeck effect in view of the said situation.

A first strain gauge of the present invention that achieves the above object has a strain gauge body having two connecting ends and formed of a first type metal,
Two first lead wires formed of the same type of metal as the first type of metal, each of which is connected to one of the two connection ends and extends;
A relay terminal in which two other ends of the two first lead wires are arranged close to each other, and heat is transferred between the two other ends while being thermally isolated from the surroundings excluding the other two ends. When,
It has two 2nd lead wires which are connected to each of the two other ends and are made of a second type metal different from the first type metal.

  According to the first strain gauge of the present invention, the relay terminal has a heat transfer action for maintaining the other two ends at the same temperature, and thermally from the surroundings excluding the other end. The two other ends of the first lead wire are maintained at substantially the same temperature by both the insulating heat insulating action.

  For this reason, even if two lead wires made of the second type metal are connected to the other two ends, generation of thermoelectromotive force due to the Seebeck effect is suppressed.

  Here, the first type metal may be constantan, and the second type metal may be copper, and the first type metal and the second type metal may be different from each other. A combination of these metals may also be used.

  Further, the relay terminal is not provided separately but may be disposed on a circuit board.

A second strain gauge of the present invention that achieves the above object has two connection terminals arranged in close proximity to each other, and a strain gauge body formed of a first type metal,
A relay terminal that thermally isolates the two connection ends from the surroundings except the two connection ends while transferring heat between the two connection ends;
It has two second lead wires made of a second type metal different from the first type metal connected to each of the two connection ends.

  In the first strain gauge of the present invention, the first lead wire is provided and the first lead wire and the second lead wire are connected on the relay terminal. However, in the second strain gauge of the present invention, The first lead wire provided in the first strain gauge of the present invention is omitted, and the first type metal provided in the strain gauge main body is changed to a configuration in which the first lead wire is directly connected to the second lead wire. This configuration may be used.

   As described above, a strain gauge capable of suppressing the generation of thermoelectromotive force due to the Seebeck effect is realized.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a strain gauge according to an embodiment of the present invention.

  FIG. 1A shows the configuration of the strain gauge, and FIG. 1B shows the configuration of the relay terminal 100 shown in FIG.

  The strain gauge 1 shown in FIG. 1 has two connection ends 11A and 11B and a strain gauge body formed of the first type metal 11, and each of the two connection ends 11A and 11B has one connection end. Two first lead wires 12A and 12B made of the same type of metal as the first type metal, and two first lead wires 12A and 12B, which are connected and extend. The other ends 120A and 120B are arranged close to each other, and the relay terminals 100 and 2 which are thermally isolated from the surroundings except the two other ends 12A1 and 12B1 while the two other ends 12A1 and 12B1 conduct heat. Two second lead wires 13A and 13B made of a second type metal different from the first type metal 11 are connected to the other ends 12A1 and 12B1, respectively.

  Here, an example is shown in which the first type of metal is constantan and the second type of metal is copper. The combination of the first type metal and the second type metal may be other combinations.

  Here, the structure of the relay terminal 100 in which the device for suppressing generation | occurrence | production of the thermoelectromotive force by Seebeck effect is elaborated is demonstrated in detail. FIG. 1B shows the configuration of the relay terminal 100 of FIG.

  In the relay terminal 100 shown in FIG. 1B, a heat insulating material 102 is stacked on a substrate 101 that is a base, and a relay terminal base 103 is further stacked on the heat insulating material 102. Two contact points 120A and 120B for relay connection are formed on the relay terminal base. The two connection ends 12A1, 12B1 of the first lead wire and the ends 13A1, 13B1 of the second lead wire are connected on the contact points 120A, 120B. Further, the contacts 120A and 120B are molded with a material 104 having good thermal conductivity.

  When the relay terminal 100 has the configuration shown in FIG. 1B, the two other ends 12A1 and 12B1 of the two first lead wires are arranged close to each other, and the two other ends 12A1 and 12B1 are heat-transferred. Therefore, the two other ends 12A1 and 12B1 can always be maintained at substantially the same temperature because they can be thermally isolated from the surroundings excluding the other two ends 12A1 and 12B1. When the temperatures of the two joining points (two other ends 12A1, 12B1) where the dissimilar metals are joined are maintained at substantially the same temperature, the connecting ends 13A, 13B of the second lead wire made of the dissimilar metals are contact points. Even when connected to 120A and 120B, generation of thermoelectromotive force due to the Seebeck effect is suppressed.

  That is, the strain gauge 1 capable of accurately measuring while suppressing the influence of the thermoelectromotive force is realized.

  FIG. 2 is a diagram showing another configuration of the relay terminal 100 shown in FIG.

  As shown in FIG. 2, in order to enhance both the heat insulating effect and the heat transfer effect of the relay terminal 100 shown in FIG. 1, a portion molded with a material having good thermal conductivity so as to surround the two contacts 120A and 120B. The heat insulating material 14 is covered from above. The configuration shown in FIG.

  FIG. 3 is a diagram showing another configuration of the relay terminal 100 shown in FIG.

  As shown in FIG. 3, in order to enhance the heat transfer effect between the two 120A and 120B of the relay terminal shown in FIG.

  Here, in the first embodiment, the example in which the relay terminal 100 is separately provided and the relay terminal 100 is connected to the measuring device has been described. However, when the strain gauge 1 is connected to the measuring device, the connection is made through the circuit board. In this case, a relay terminal may be provided on the circuit board.

  FIG. 4 is a diagram illustrating an example in which a relay terminal is provided on a circuit board.

  In FIG. 4, the relay terminal 100 of FIG. 1 is provided on the circuit board P1, and an air hole P1C is provided around the contacts P1A and P1B instead of the heat insulating material shown in FIG. ing. At this time, the two other ends 12A1.12B1 of the first lead wire 12 are connected to the two contacts P1A and P2B on the circuit board, respectively, while transferring heat between the two contacts. It is thermally isolated from the surroundings except for the other end 12A1, 12B1. Such a configuration may be used.

  FIG. 5 is a diagram for explaining a modification of FIG.

  When the other contact P2B ′ is provided so as to surround one contact P2A as shown in FIG. 5, the heat transfer effect between the contacts P2A and P2B ′ is further enhanced, and the temperature between the two contacts is more reliably equal temperature. To be kept.

  FIG. 6 is a diagram showing another embodiment.

  In the first embodiment, the first lead wires 12A and 12B are provided and the lead wires are lengthened to provide easy wiring. However, when the wiring does not require a long length, the first lead wires are provided. 12A and 12B can be omitted.

  A strain gauge 10 shown in FIG. 6 has two connection ends 11A and 11B arranged in close proximity to each other, and includes a strain gauge body 1A formed of a first type metal (constantan), and two connection ends 11A, 11B is connected to the relay terminal 100 and the two connection ends 11A and 11B, which are thermally isolated from the surroundings except for the two connection ends 11A and 11B, while transferring heat between the two connection ends 11A and 11B. The second lead wires 13A and 13B are made of a second type metal different from the first type metal. Instead of the configuration shown in FIGS. 1A and 1B, the configuration shown in FIGS. 6A and 6B may be used.

It is a figure which shows the structure of the strain gauge which is one Embodiment of this invention. It is a figure which shows another structure of the relay terminal 100 shown in FIG. It is a figure which shows another structure of the relay terminal 100 shown in FIG. It is a figure explaining the example at the time of providing a relay terminal on a circuit board. It is a figure explaining the modification of FIG. It is a figure which shows 2nd Embodiment.

Explanation of symbols

1 2 Strain gauge 11 First type of metal (constantan)
11A 11B Connection end 12A 12B First lead wire (constantan)
12A1 12B1 Two connection ends of the first lead wire 120A 120B Contact point 13A 13B Second lead wire (copper)
13A1 13B1 Two connection ends of the second lead wire (copper) 14 Heat insulating material 100 Relay terminal 101 Substrate 102 Heat insulating material 103 Relay terminal 103A Relay terminal made of a material having good thermal conductivity 104 Thermal conductivity good material

Claims (4)

A strain gauge body having two connecting ends and formed of a first type of metal;
Two first lead wires formed of the same type of metal as the first type of metal, each extending from one of the two connection ends connected thereto; and
A relay terminal in which two other ends of the two first lead wires are arranged close to each other so that heat is transferred between the two other ends and is thermally isolated from the surroundings except for the other two ends. When,
A strain gauge comprising two second lead wires made of a second type of metal different from the first type of metal connected to each of the two other ends.   The strain gauge according to claim 1, wherein the first type of metal is constantan and the second type of metal is copper.   The strain gauge according to claim 1, wherein the relay terminal is disposed on a circuit board. A strain gauge body having two connection terminals arranged close to each other and formed of a first type of metal;
A relay terminal that thermally isolates the two connection ends from the surroundings excluding the two connection ends while transferring heat between the two connection ends;
A strain gauge comprising two second lead wires made of a second type of metal different from the first type of metal connected to each of the two connection ends.

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