JPH0886700A - Load cell unit - Google Patents

Abstract

PURPOSE: To realize an accurate temperature compensation by thermally coupling a temperature sensor with the surface of a strain generator, thereby detecting the temperature regardless of fluctuation in the ambient temperature or the air flow. CONSTITUTION: A printed wiring board 3 constituting a data processing section C is fixed, by means of a screw 5, to the strain generator 1 of a load cell B through a spacer 4. The lead 2a of a temperature sensor 2 is soldered to the circuit on the board 3 and the temperature sensor is fixed with the heat-sensitive part 2b thereof touching the surface of the strain generator 1. With such structure, the sensor 2 can detect the temperature of a strain gauge 7, having a significant relationship with the temperature characteristics of the sensor 2, through the strain generator 1. Since the temperature of the strain generator 1 is not susceptible to fluctuation in the ambient temperature, a stabilized output can be obtained regardless of fluctuation in the ambient temperature or the air flow. This structure realizes a accurate temperature compensation based on the stabilized output from the sensor 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature compensation of load cell units.

[0002]

2. Description of the Related Art As shown in FIG. 10, a load cell unit A comprises a load cell B and a data processing section C for digitally converting a signal converted into an electric signal by the load cell B. The load cell B is configured by attaching a strain gauge to the flexure element 1.

Since the output of this load cell unit A has a temperature characteristic, the temperature sensor 2 is arranged in the vicinity of the load cell B and the temperature sensor 2 is incorporated into the electric circuit of the load cell B to output the output of the load cell B. Temperature compensation is performed based on the ambient temperature detected by the temperature sensor 2, or the output of the load cell B and the output of the temperature sensor 2 are separately captured in the data processing unit C and digitally temperature compensated by a microcomputer.

A preamplifier and a A constituting the data processing unit C
Since the / D converter also has a temperature characteristic, it can be seen that the data processing unit C is also provided with a temperature sensor to similarly perform temperature compensation.

[0005]

In the conventional load cell unit A, since the temperature sensor 2 detects the atmospheric temperature of the load cell unit A, correct temperature correction can be performed when this atmosphere is thermally stable. It is possible, but the current situation is that temperature cannot be compensated accurately if there is uneven temperature or air flow (wind).

An object of the present invention is to provide a load cell unit capable of obtaining a stable output even if the atmosphere has temperature unevenness or the flow of air.

[0007]

According to a first aspect of the present invention, there is provided a load cell unit in which a load is supported by a strain-generating body, deformation of the strain-generating body is detected by a strain gauge and converted into an electric signal. A sensor and a data processing unit that outputs a signal that is detected by a strain gauge and converted into an electric signal by performing temperature correction based on the detection signal of the temperature sensor are provided, and the temperature sensor is provided on the surface of the strain body. It is characterized by being thermally bonded.

A load cell unit according to a second aspect of the present invention is a load cell unit in which a measured load is supported by a strain-generating body, and deformation of the strain-generating body is detected by a strain gauge and converted into an electric signal by a temperature sensor and a strain gauge. A data processing unit for temperature-correcting and outputting the signal detected and converted into an electric signal based on the detection signal of the temperature sensor is provided, and the temperature sensor is inserted into the concave portion formed in the strain-flexing body. It is characterized in that the strain body and the temperature sensor are thermally coupled.

According to a third aspect of the load cell unit of the first or second aspect, the exposed portion of the temperature sensor is molded with a heat insulating material.

A load cell unit according to a fourth aspect of the present invention is a load cell unit in which a measured load is supported by a strain-generating body, deformation of the strain-generating body is detected by a strain gauge and converted into an electric signal, by a temperature sensor and a strain gauge. A data processing unit for detecting and converting a signal converted into an electric signal to output the temperature based on the detection signal of the temperature sensor is provided, and the temperature sensor is thermally coupled to the strain-generating body,
The circuit element of the data processing unit is thermally coupled to the strain generating element.

A load cell unit according to a fifth aspect of the present invention is the load cell unit according to the fourth aspect, wherein a heating element of the circuit elements of the data processing section is thermally coupled to the strain generating element.

According to a sixth aspect of the present invention, in the load cell unit according to the fourth or fifth aspect, the exposed portion of the temperature sensor and the exposed portion of the circuit element of the data processing unit are molded with a heat insulating material. To do.

[0013]

According to the structure of the first aspect, since the temperature sensor is thermally coupled to the surface of the strain-generating body, the temperature can be detected without being influenced by the temperature unevenness of the atmosphere, and accurate temperature compensation can be realized.

According to the structure of the second aspect, since the temperature sensor is inserted into the concave portion formed in the strain-generating body and the strain-generating body and the temperature sensor are thermally coupled, the temperature is detected without being affected by the temperature unevenness of the atmosphere. Therefore, accurate temperature compensation can be realized.

According to the structure of claim 3, since the exposed portion of the temperature sensor is molded with a heat insulating material in claim 1 or 2, there is no heat flow from the exposed portion of the temperature sensor to the atmosphere, and accurate temperature compensation is performed. Can be realized.

According to the structure of claim 4, since the temperature sensor is thermally coupled to the strain-generating body and the circuit element of the data processing unit is thermally coupled to the strain-generating body, the temperature sensor, the strain-generating body, and the data processing unit are connected. A thermal equilibrium state between circuit elements is obtained, and accurate temperature compensation can be realized with a single temperature sensor.

According to the structure of claim 5, in the load cell unit according to claim 4, since the heating element of the circuit elements of the data processing section is thermally coupled to the strain body, the heat of the heating element of the data processing section is generated. The heat is dissipated through the strain generating element, and the temperature unevenness can be reduced to realize accurate temperature compensation.

According to the structure of claim 6, in the load cell unit according to claim 4 or 5, the exposed portion of the temperature sensor and the exposed portion of the circuit element of the data processing portion are molded with a heat insulating material, so that the temperature sensor is exposed. Accurate temperature compensation can be realized without heat flow from the part to the atmosphere.

[0019]

Embodiments of the present invention will be described below with reference to FIGS. It should be noted that components having the same functions as those of the conventional example shown in FIG.

1 and 3 show a first embodiment. The printed wiring board 3 on which the data processing unit C is configured is a spacer 4
It is attached to the flexure element 1 of the load cell B by means of screws 5. The lead 2a of the temperature sensor 2 is soldered to the circuit of the printed wiring board 3, and the heat sensitive portion 2b is attached so as to come into contact with the surface of the flexure element 1.

The exterior case of the load cell unit is shown in FIG.
An electric circuit as shown in is built in. The bridge circuit 6 is composed of a strain gauge 7 attached to the flexure element 1. The output of the bridge circuit 6 is digitally converted by the A / D converter 10 via the preamplifier 8 and the low-pass filter 9. In the microcomputer 11, the output is temperature-compensated based on the temperature detected by the temperature sensor 2. The microcomputer 11 corrects the output based on the storage characteristic of the characteristic storage memory 12, and further, the communication transceiver 13
Is output to the outside via.

The reference voltage generation circuit 14 generates a reference voltage Vr based on the excitation voltage of the bridge circuit 6, and A /
The D converter 10 digitally converts the input signal using the reference voltage Vr as a conversion reference. Load cell unit A
The power of the power circuit 1 is a voltage Vp supplied from the outside of the load cell unit A mounted on the printed wiring board 3.
5, the voltage is converted and power is supplied to each part.

In the case of such a configuration, the temperature sensor 2 can detect the temperature of the strain gauge 7 which is greatly related to the temperature characteristic via the strain-generating body 1. Further, since the temperature of the flexure element 1 is not easily influenced by the temperature unevenness of the atmosphere, a stable output can be obtained even if the atmosphere has temperature unevenness or the air flow, and an accurate output based on the output of the temperature sensor 2 is obtained. Expect temperature compensation.

FIG. 2 shows a second embodiment. The printed wiring board 3 on which the data processing section C is configured is attached to the flexure element 1 of the load cell B via a spacer 4 with screws 5. The lead 2a of the temperature sensor 2 is soldered to the circuit of the printed wiring board 3, and the heat sensitive portion 2b is inserted into the recessed portion 1a formed in the flexure element 1 and attached to the recessed portion 1a.
Silicon grease is filled between the inner peripheral surface and the heat sensitive portion 2b in order to improve heat conduction.

The data processing section C is the same as that shown in FIG. In the case of such a configuration, the temperature sensor 2 can detect the temperature of the strain gauge 7 which is greatly related to the temperature characteristic via the strain body 1.

Further, since the temperature of the flexure element 1 is not easily influenced by the temperature unevenness of the atmosphere, the temperature unevenness may occur in the atmosphere.
A stable output can be obtained even in the presence of air flow, and accurate temperature compensation based on the output of the temperature sensor 2 can be expected.

4 and 5 show the third and fourth embodiments.
FIG. 4 is a modification of the first embodiment, and FIG. 5 is a modification of the second embodiment. In FIG. 4, the heat sensitive portion 2b and the lead 2 of the temperature sensor 2 are shown.
a is covered with silicon rubber 16 as a heat insulating material.
In FIG. 5, the lead 2a of the temperature sensor 2 is covered with a silicon rubber 16 as a heat insulating material.

As the heat insulating material, urethane rubber, calcium silicate material, rock wool material or the like can be used in addition to silicon rubber. With such a configuration, the temperature sensor 2 can be shielded from the atmosphere by the silicon rubber 16, and the temperature sensor 2 can detect the temperature of the strain gauge 7 more accurately without being affected by the air flow of the atmosphere. Yes, more accurate temperature compensation can be expected.

FIG. 6 shows a fifth embodiment. FIG. 6 shows a modification of the first embodiment, in which the preamplifier 8 and the A of the data processing unit C are provided.
The / D converter 10 and the circuit element 14a of the reference voltage generation circuit 14 are mounted on the printed wiring board 3 so as to be thermally coupled to the surface of the strain body 1.

When the mounting heights of the components of the data processing unit C vary, silicon is used to improve heat conduction between the surface of the strain generating element 1 and the components of the data processing unit C. The grease is filled.

With this configuration, it is possible to create a thermal equilibrium state between the flexure element 1, the temperature sensor 2, and the parts of the data processing section C that are involved in the temperature characteristics, and the single temperature sensor 2 is used. Thus, temperature compensation of the load cell B and the data processing unit C can be performed.

FIG. 7 shows a sixth embodiment. FIG. 7 shows a modification of the fifth embodiment, in which parts of the temperature sensor 2 and the data processing section C relating to temperature characteristics and a part of the strain body 1 are covered with a silicon rubber 16 as a heat insulating material. It is being appreciated.

As the heat insulating material, urethane rubber, calcium silicate material, rock wool material or the like can be used in addition to silicon rubber. With such a configuration, the temperature sensor 2 can be shielded from the atmosphere by the silicon rubber 16, and the temperature sensor 2 can detect the temperature of the strain gauge 7 more accurately without being affected by the air flow of the atmosphere. Yes, more accurate temperature compensation can be expected.

FIG. 8 shows a seventh embodiment. In FIG. 8, the voltage regulator 15a of the power supply circuit 15 is in contact with the surface of the flexure element 1 and is thermally coupled thereto. In this case, the heat generated by the voltage regulator 15a is radiated through the flexure element 1, and the temperature unevenness of the atmosphere due to the heat generated by the voltage regulator 15a can be reduced.

It is possible that the heat received from the voltage regulator 15a causes a temperature difference between the temperature of the flexure element 1 and the ambient temperature. However, a portion related to the temperature characteristics of the load cell unit A is thermally coupled to the flexure element 1. Since a thermal equilibrium state is created through the strain generating element 1, the temperature of the system can be represented by the temperature of the strain generating element 1, and accurate temperature compensation can be realized based on the output of the temperature sensor 2. .

In this embodiment, the case where the voltage regulator 15a is used as an element that generates heat is explained as an example. Can also be expected to have the same effect.

FIG. 9 shows an eighth embodiment. FIG. 9 is a modification of the seventh embodiment, in which each element thermally coupled to the strain generating element 1 and a part of the surface of the strain generating element 1 are covered with a silicon rubber 16 as a heat insulating material.

As the heat insulating material, urethane rubber, calcium silicate material, rock wool material or the like can be used in addition to silicon rubber. With such a configuration, the temperature sensor 2 can be shielded from the atmosphere by the silicon rubber 16, and the temperature sensor 2 can detect the temperature of the strain gauge 7 more accurately without being affected by the air flow of the atmosphere. Yes, more accurate temperature compensation can be expected.

[0039]

According to the first aspect of the invention, since the temperature sensor is thermally coupled to the surface of the flexure element, the temperature can be detected without being affected by the temperature unevenness of the atmosphere, and accurate temperature compensation can be realized. It is possible to improve the performance of the load cell unit.

According to the structure of the second aspect, since the temperature sensor is inserted into the concave portion formed in the strain-generating body and the strain-generating body and the temperature sensor are thermally coupled, the temperature is detected without being affected by the temperature unevenness of the atmosphere. Therefore, accurate temperature compensation can be realized, and the performance of the load cell unit can be improved.

According to the third aspect of the present invention, since the exposed portion of the temperature sensor is molded with a heat insulating material in the first or second aspect, there is no heat flow from the exposed portion of the temperature sensor to the atmosphere, and accurate temperature compensation is performed. Can be realized.

According to the structure of claim 4, since the temperature sensor is thermally coupled to the strain-generating body and the circuit element of the data processing unit is thermally coupled to the strain-generating body, the temperature sensor, the strain-generating body and the data processing unit are connected. A thermal equilibrium state between circuit elements is obtained, and accurate temperature compensation can be realized with a single temperature sensor.

According to the fifth aspect of the present invention, in the load cell unit according to the fourth aspect, since the heating element of the circuit elements of the data processing section is thermally coupled to the strain body, the heat of the heating element of the data processing section is generated. The heat is dissipated through the strain generating element, and the temperature unevenness can be reduced to realize accurate temperature compensation.

According to the structure of claim 6, in the load cell unit according to claim 4 or 5, the exposed portion of the temperature sensor and the exposed portion of the circuit element of the data processing portion are molded with a heat insulating material, so that the temperature sensor is exposed. Accurate temperature compensation can be realized without heat flow from the part to the atmosphere.

[Brief description of drawings]

FIG. 1 is a front view of an essential part of a first embodiment of a load cell unit of the present invention.

FIG. 2 is a partially cutaway front view of the second embodiment.

FIG. 3 is an electrical configuration diagram of a load cell unit.

FIG. 4 is a front view of the main part of the third embodiment.

FIG. 5 is a partially cutaway front view of the fourth embodiment.

FIG. 6 is a front view of the essential portions of the fifth embodiment.

FIG. 7 is a front view of a main portion of a sixth embodiment.

FIG. 8 is a front view of the essential parts of the seventh embodiment.

FIG. 9 is a front view of the essential portions of the eighth embodiment.

FIG. 10 is an explanatory diagram of a conventional load cell unit.

[Explanation of symbols]

 A load cell unit B load cell C data processing unit 1 strain element 2 temperature sensor 3 printed wiring board 10 A / D converter 11 microcomputer 15a voltage regulator 16 silicon rubber

Claims (6)

[Claims] 1. A load cell unit in which a load is supported by a strain-generating body, deformation of the strain-generating body is detected by a strain gauge and converted into an electric signal, and detected by a temperature sensor and a strain gauge and converted into an electric signal. And a data processing unit for temperature-correcting and outputting the generated signal based on the detection signal of the temperature sensor, and the temperature sensor is thermally coupled to the surface of the strain body. 2. A load cell unit for supporting a measured load with a strain-generating body, detecting deformation of the strain-generating body with a strain gauge and converting it into an electric signal, and detecting it with a temperature sensor and a strain gauge and converting it into an electric signal. And a data processing unit for temperature-correcting and outputting the generated signal based on the detection signal of the temperature sensor, and inserting the temperature sensor into a recess formed in the strain-generating body to form the strain-generating body and the temperature sensor. Thermally coupled load cell unit. 3. The load cell unit according to claim 1, wherein the exposed portion of the temperature sensor is molded with a heat insulating material. 4. A load cell unit for supporting a measurement load with a strain-generating body, detecting deformation of the strain-generating body with a strain gauge and converting it into an electric signal, and detecting it with a temperature sensor and a strain gauge and converting it into an electric signal. And a data processing unit for correcting the temperature of the generated signal based on the detection signal of the temperature sensor and outputting the temperature signal, the temperature sensor being thermally coupled to the strain-generating body, and the circuit element of the data processing unit being activated. A load cell unit that is thermally coupled to a strain body. 5. The load cell unit according to claim 4, wherein a heating element of the circuit elements of the data processing section is thermally coupled to the strain generating element. 6. The load cell unit according to claim 4, wherein the exposed portion of the temperature sensor and the exposed portion of the circuit element of the data processing unit are molded with a heat insulating material.