JPS6217693Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a load cell in which a strain gauge is attached to a strain-generating portion that deforms in response to a load.

Conventionally, in this type of load cell, a correction resistor has been used to correct the temperature characteristics of the Young's modulus of the load cell body made of aluminum material, etc., and this correction resistor has been used to compensate for the strain-generating parts such as fixed pillars. It is attached in a position where it will not be affected. However, the part that requires temperature characteristic correction of Young's modulus is a strain-generating part when viewed locally, and the correction resistor cannot perform complete correction unless it follows the temperature of the strain-generating part. be. Therefore, in the conventional position, it takes a considerable amount of time from the start of energization until the temperature of each part becomes constant, making it difficult to perform accurate measurement.

This idea was devised in view of these points, and it is possible to start measurements immediately after starting energization.
The purpose is to obtain a load cell that is less susceptible to the effects of heat sources such as circuit parts.

In this invention, a resistor for correcting the temperature coefficient of Young's modulus is attached to the rigid body part located in the middle of the thin flexible part, so it can follow the averaged temperature of the thin flexible part. The error is small even when measured immediately after the start, and even if the thin deformed part deforms when a load is applied, the rigid part to which the resistor is attached does not deform, so it is not affected by the applied load. Further, even if a heat source is located nearby and the temperature of the thin flexible portion changes, the temperature of the resistor can be reliably followed.

A first embodiment of this invention will be explained based on FIGS. 1 and 2. First, the load cell main body 1 is formed from a high-strength aluminum alloy, etc., and this load cell main body 1 is made by processing a plate material of a certain thickness, and consists of a fixed support section 2, a movable support section 3, and two arms 4, 5.
It is formed into a parallelogram shape. The bottom surface 6 of the fixed column 2 is fixed to a base (not shown), and the upper surface of the movable column 3 is formed with a screw hole 7 to which a mounting plate (not shown) is connected. The upper surface of the arm 4 and the arm 5
A concave surface 8 with a predetermined step is formed between the top surface and the top surface. Next, an irregularly shaped hole 9 in which two oval holes are arranged in series is formed in the central part, and a rigid body part 10 is formed in the central part of the arms 4 and 5 by this irregularly shaped hole 9, and a rigid body part 10 is formed on both sides of this rigid body part 10. A thin flexible portion 11 is formed. On the outer surface of these thin flexible parts 11, strain gauges 12, 13, 14,
15 is attached. Further, a resistor 16 for correcting the temperature coefficient of Young's modulus of the load cell main body 1 is attached to the rigid body part 10. moreover,
A PC board 17 is attached to the side surface of the fixed support 2, and the strain gauge 1 is attached to this PC board 17.
2, 13, 14, and 15 are bridge-wired, and has an input terminal 18 and an output terminal 19, and
The resistor 16 is wired to the input side. Furthermore, a lead wire 20 is drawn out from the PC board 17 to be connected to a circuit section (not shown).

In such a configuration, the resistor 16 is generally called a span resistor and is made of nickel or nickel alloy foil, and is attached at a position where the strain gauges 12, 13, 14, and 15 are attached. Since the rigid body part 10 is located in the middle of the thin-walled flexible part 11, the temperature almost matches that of the thin-walled flexible part 11. Therefore, immediately after the start of energization, the temperature coefficient of Young's modulus is corrected in accordance with the temperature of the thin flexible portion 11, and no error occurs in the measured value. Moreover, when a load is applied, the thin-walled deformed portion 11
The rigid body part 10 to which the resistor 16 is attached even if the
Since the resistor 16 does not deform, the output of the resistor 16 is not affected by load application. Furthermore, even if the load cell main body 1 is heated by the circuit section or the like after energization, the temperature of the rigid body section 10 is almost the same as the temperature of the thin flexible section 11, so correction is made according to the temperature change, and the resistor 16 is heated. A phenomenon in which the correction is inappropriate as in the case of adhering to the fixed support column 2 does not occur. Furthermore, strain gauges 12, 13, 14,
Even if the resistor 15 generates heat, the temperature of the resistor 16 is quickly followed, and the temperature of the thin flexible portion 11 and the resistor 16 are
There is no large difference between the temperature and the temperature, and no error occurs.

In addition, in actual practice, the resistor 16 may be attached to the rigid body part 10 of the lower arm 5.

Next, a second embodiment of this invention will be described based on FIGS. 3 and 4. In this embodiment, the resistance value of the resistor 16 in the previous embodiment is divided into two, and two resistors 21 and 22 are attached to the rigid body parts 10 of the arms 4 and 5, respectively.
are connected in series. Therefore, the resistors 21 and 22 are present in the vicinity of the four thin-walled flexible parts 11, respectively, and errors in the correction are further eliminated.

This idea involves attaching a resistor for correcting the temperature coefficient of Young's modulus of the load cell body to the rigid body part formed in the middle part of the arm located between the fixed column part and the movable column part as mentioned above. Therefore, the temperature of the thin-walled flexible part and the resistor can be made the same, which makes it possible to perform error-free measurements immediately after energization.Moreover, the thin-walled deformed part does not deform when a load is applied. Since the rigid body part to which the resistor is attached does not deform even when the resistor is attached, it is not affected by the applied load, and even if the temperature changes due to external conditions, the temperature followability is good and there are no errors. It is something that you have.

[Brief explanation of the drawing]

1 is a perspective view showing a first embodiment of this invention, FIG. 2 is a circuit diagram, FIG. 3 is a perspective view showing a second embodiment of this invention, and FIG. 4 is a circuit diagram. 1...Load cell body, 2...Fixed support part, 3
. . . Movable strut portion, 4 to 5 .

Claims (1)

[Scope of utility model registration request] A fixed column and a movable column to which the mounting plate is connected are vertically opposed to each other, and the fixed column and the movable column are connected at the top and bottom with horizontal arms, and the central part of these arms is made into a rigid body. The present invention is characterized in that a load cell body is provided with a thin flexible part formed at both ends to which a strain gauge is attached, and a resistor for correcting the temperature coefficient of Young's modulus of the load cell body is attached to the rigid body part of the arm. load cell.