JP2000180251A - Mounting structure of sensing element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the mounting structure of a sensing element, capable of reducing the dispersion of output values of the sensing element. SOLUTION: This mounting structure is a structure for mounting a sensing element 7 for load measurement to a accommodation recess 5 h formed in an object 5 to be measured, to which the load of the vehicle is applied, through a case assembly. The case assembly is composed of a plurality of fixing members 8 to fix the end of the sensing element 7 to the accommodation recess 5 h. Each fixing member 8 is provided with sensing element fixing parts to be fixed to the ends of the sensing element 7 and mounting pieces to be fixed on the object. The sensing element fixing parts are welded so as to cross the detection direction of the deformation in the sensing element 7. The mounting pieces are welded so as to cross the direction of the load applied to the object 5, while fixing the sensing element fixing parts to the ends of the sensing element 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting a sensing element such as a strain gauge sensor for detecting a load applied to an object to be measured.

[0002]

2. Description of the Related Art For example, in a large vehicle such as a truck of a vehicle, a load measuring device is mounted on the vehicle itself for the purpose of preventing a traffic accident such as a rollover due to overloading, and the promotion of deterioration of the vehicle and the road surface. Is measured. In this load measuring device, the load at the installation location is detected by sensing elements provided on the front and rear wheels of the vehicle and the like, and the load is measured based on the value of a signal that changes according to the load output from the sensing element. ing.

[0003] As this sensing element, for example, there is a strain gauge sensor for detecting a strain, and the load applied to a measurement object is measured by calculating the output value of such a sensing element.

A sensing element used in this type of load measuring device is generally housed and fixed in a case assembly formed corresponding to the shape of the sensing element, and the sensing element fixed to the case assembly has the shape of the case assembly. Are accommodated and fixed together with a case assembly in an accommodation recess formed in the measurement object. The above-mentioned respective housings are fixed by laser welding, electric resistance welding or the like.

[0005]

However, since the components such as the sensing element and the case assembly described above are workpieces formed by machining, the dimensions of each component are limited to the maximum and minimum dimensions allowable for the workpiece. A dimensional tolerance, which is a difference, occurs, and this dimensional tolerance cannot be eliminated.
Therefore, as shown in the cross-sectional view of the mounting structure of the sensing element to the case assembly in FIG. 4, if there is a dimensional tolerance between the width a of the sensing element 7 and the inner diameter b of the case assembly 10, the sensing element 7 is 1
0, a gap δ occurs.

In such a state, if the sensing element 7 and the case assembly 10 are welded in the same direction as the strain detection direction A of the sensing element 7, the gap δ between the sensing element 7 and the case assembly 10 is canceled. And welded. Thereafter, the welded portion is contracted by the cooling. Therefore, the sensing element 7 is in the distortion detection direction A
In other words, it is fixed to the case assembly 10 in a state where it is constantly pulled, that is, in a state where distortion occurs.
That is, if welding is performed so as to cancel the gap δ generated by the dimensional tolerance between the sensing element 7 and the case assembly 10, the initial distortion occurs in the sensing element 7, so that the sensing element 7 outputs according to the load. There was a problem that signals varied from product to product.

[0007] Further, since the measurement object for accommodating and fixing the case assembly is also a work, if there is a dimensional tolerance in the shape of the concave portion for accommodating the measurement object, when the case assembly is accommodated in the concave portion for accommodating the measurement object. Therefore, a gap is generated between the case assembly and the housing recess. Therefore, as described above,
If welding is performed so as to cancel the gap, the case assembly will be fixed to the measurement object while being constantly pulled in the direction in which the load is applied. That is, if the case assembly is fixed in a pulled state, the sensing element fixed inside the case assembly is also pulled. As a result, the initial distortion generated in the sensing element or the initial distortion generated in the sensing element 7 is further increased. Therefore, it is difficult to accurately transmit the load applied to the measurement object to the sensing element, and the output value from the sensing element 7 further varies.

Accordingly, the present invention has been made in view of the above-described problems,
An object of the present invention is to provide a mounting structure of a sensing element that can reduce a variation in an output value of the sensing element.

[0009]

According to a first aspect of the present invention, there is provided a sensing element mounting structure according to the present invention, wherein a case assembly is provided in a housing recess formed in a measurement object to which a load of a vehicle is applied. A structure for mounting a sensing element for load measurement through the case assembly, wherein the case assembly is constituted by a plurality of fixing members for fixing the end of the sensing element and the housing recess, and each of the fixing members is A sensing element fixing portion fixed to an end of the sensing element, and a mounting piece fixed to the object to be measured, wherein the sensing element fixing portion intersects a direction in which distortion is detected in the sensing element. The welding piece is welded to the end of the sensing element,
In a state where the sensing element fixing section and the end of the sensing element are fixed, the sensing element is welded to the object so as to intersect with the direction of the load applied to the object.

[0010] According to the mounting structure of the sensing element of the present invention, the sensing element is attached to the object to be measured by welding via the fixing member. This welding is performed so as to intersect the direction in which the sensing element detects distortion and the direction of the load applied to the measured object.
When a load is applied to the measurement object, the sensing element is distorted in accordance with the load, and outputs a signal having a level corresponding to the load. With such a structure,
Since the welding is not performed in the same direction as the direction of detecting the strain in the sensing element and the direction of the load applied to the measurement object, even if a gap is generated between the members due to dimensional tolerance, the sensing element detects the direction of the strain. , And the sensing element can be attached to the measurement object without the fixing member being pulled in each of the directions of the load. Therefore, the initial distortion of the sensing element generated for each product can be reduced due to the dimensional tolerances of the sensing element, the fixed member, and the members of the measurement object.

According to a second aspect of the present invention, there is provided a sensing element mounting structure according to the first aspect, wherein an edge of the sensing element in a direction in which distortion is detected is formed by the fixing member. Characterized by being fixed so as to contact with.

According to the mounting structure of the sensing element of the present invention, the edge of the sensing element is fixed so as to be in contact with the fixing member. When a load is applied to the measurement object, the sensing element is distorted in accordance with the load, and outputs a signal having a level corresponding to the load. With such a structure, the contact area between the fixed member and the sensing element can be increased, so that the load applied to the measured object can be transmitted to the sensing element more accurately.

According to a third aspect of the present invention, there is provided a sensing element mounting structure according to the first or second aspect, wherein the sensing element fixing portion has a pair of legs. The pair of legs is fixed so as to sandwich an end of the sensing element.

According to the third aspect of the present invention, the sensing element is fixed so as to be sandwiched between the end of the sensing element and the pair of legs of the fixing member. When a load is applied to the measurement object, the load is transmitted to the sensing element via the pair of legs of the fixed member, and the transmitted load distorts the sensing element.
A signal of a level corresponding to the load is output. With such a structure, the load can be dispersed to the pair of legs of the fixed member and transmitted to the sensing element, so that the load due to the fixed portion can be reduced and the sensing element can be stably maintained. Can be fixed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mounting structure of a sensing element according to an embodiment of the present invention will be described below with reference to FIGS. 1A is a partial cross-sectional view showing the arrangement of a measurement object to which the mounting structure of the present invention is applied, FIG. 1B is a partial front view of the same, and FIG. 2 is housed and fixed in the measurement object of FIG. 3A is a front view of the sensing element to which the fixing member of FIG. 1 is fixed, and FIG. 3B is a cross-sectional view of the same.

In FIG. 1, reference numeral 5 denotes an object to be measured, and the object to be measured 5 is a member such as a shackle pin or a trunnion bracket which is relatively displaced by the load. . The measurement object 5 is formed with a housing recess 5h having a substantially prismatic outer shape, and a recess 5k smaller than the housing recess 5h is formed on the abutting surface of the housing recess 5h. And the accommodation recess 5
A step 5s is formed at the boundary between the h and the recess 5k, and the sensing element 7 is fixed to the step 5s via a fixing member 8.

As shown in FIG. 2, the above-described sensing element 7 is a compression force detection type sensor that detects distortion due to compression force and outputs a signal corresponding to the distortion. It has a shaped member 7a and a coil 7g as a sensing part. The plate-shaped member 7a is formed in a flat plate shape from a magnetic material such as permalloy, and includes a substantially central coil portion 7b extending in the longitudinal direction and ends 7d, 7d on both sides serving as a fixed portion. It is configured.

Four through holes 7f are formed in the coil portion 7b at intervals in the longitudinal direction and the width direction orthogonal to the longitudinal direction. The coil 7g has two magnet wires 7h constituting a cross coil, and these magnet wires 7h are covered with an insulating material (not shown) such as enamel. One of the two magnet wires 7h is wound around the two through holes 7f, 7f so as to cross the longitudinal direction diagonally,
Both ends are pulled out from the through holes 7f, 7f, respectively.
The other is wound so as to cross the remaining two through holes 7f, 7f obliquely in the longitudinal direction, and has both ends at the respective through holes 7f, 7f.
7f respectively.

As shown in FIG. 3, reference numeral 8 denotes a fixing member.
The fixing member 8 includes a pair of legs 8a, 8a and a mounting piece 8b. The pair of legs 8a, 8a is formed in a U-shape by a connecting portion 8c that connects the bases of the pair of legs 8a, 8a to each other. And the mounting piece 8b
Are integrally formed as a plate-shaped member so as to be continuously provided from the connecting portion 8c.

In the above-described embodiment, the fixing members 8, 8 fixed to both ends of the sensing element 7 correspond to a conventional case assembly. And leg 8
“a” corresponds to the sensing element fixing part in the claims.

Next, the attachment of the sensing element 7 to the measurement object of the embodiment configured as described above will be described. First, as shown in FIG.
The end 7d, which is one end of the fixing member 8, is connected to a pair of legs 8 of the fixing member 8.
a, 8a, and the connecting portion 8 between the edge 7e of the sensing element 7 in the direction in which the distortion is detected and the fixing member 8.
Attach so that c contacts. The fixing member 8 is similarly attached to the other end of the sensing element 7.

Then, as shown in FIG. 3B, in a state where the fixing member 8 is mounted on the sensing element 7, the fixing member 8 is set from above so as to be substantially perpendicular to the direction in which the sensing element 7 detects distortion. Is irradiated with a laser beam, and the end 7d of the sensing element 7 and the leg 8a are laser spot welded. When the welding on one side is completed in this way, the laser spot welding between the end 7d of the sensing element 7 and the leg 8a on the opposite side is performed similarly.

When the fixing members 8 are fixed to both ends of the sensing element 7 in this way, the sensing element 7 is inserted from the opening side of the housing recess 5h of the measured object 5, and the distortion in the sensing element 7 can be detected. The positions of the mounting pieces 8b, 8b of the fixing members 8, 8 and the steps 5s in the measurement object 5 are aligned so that the direction matches the direction in which the measurement object 5 is displaced when a load is applied. Then, a laser beam is irradiated from the opening side of the housing recess 5h so as to be substantially perpendicular to the direction in which the strain is detected in the sensing element 7, and the mounting piece 8b of each fixing member 8 and the step 5s in the measurement object 5 are separated. Let it be welded. By performing welding in this manner, the sensing element 7 is fixed to the measurement object 5 via the fixing member 8.

Next, the operation of the vehicle load measuring sensing element 7 assembled as described above will be described.
As shown in FIG. 1, the vehicle load applied to the measurement object 5 and the reaction force generated according to the load are transmitted to the sensing element 7 via the fixing member 8 welded to the step 5s. As a result, a compressive force according to the load acts on the sensing element 7, and the coil section 7b of the sensing element 7 is distorted by the compressive force, and a sensing signal of a level corresponding to the distortion is output.

As described above, according to the mounting structure of the sensing element 7 in the embodiment, the end 7d of the sensing element 7 is connected to the pair of legs 8a, 8a of the fixing member 8.
In the state where the sensing element 7 detects the distortion, the welding is performed so as to be substantially perpendicular to the direction in which the sensing element 7 detects the distortion.
Laser spot welding between the mounting piece 8b of the measuring object 5 and the step portion 5s of the measuring object 5, the sensing element 7 is attached to the housing recess 5 of the measuring object 5.
h.

That is, a pair of legs 8a, 8a of the fixing member 8
In this state, the end 7d of the sensing element 7 is sandwiched, and in this state, welding is performed so as to be substantially perpendicular to, that is, intersect with, the direction in which the sensing element 7 detects the strain. No welding is performed in the detection direction. As a result, even if a gap is formed between members due to the respective dimensional tolerances of the sensing element 7 and the fixing member 8, the sensing element 7 can be fixed to the fixing member 8 in a state where the sensing element 7 is pulled by welding in the strain detection direction. Disappears. Therefore, the initial distortion caused by attaching the sensing element 7 to the fixing member 8 can be reduced. Therefore, since an accurate signal corresponding to the load applied to the sensing element 7 can be output, the variation in the output value of the sensing element 7 that occurs for each product can be reduced.

Furthermore, since the mounting piece 8b of the fixing member 8 and the step 5s of the measured object 5 are overlapped with each other and are welded so as to be substantially perpendicular to the direction in which the load is applied to the measured object 5, that is, to intersect. The fixing member 8 is no longer fixed to the housing recess 5h of the measurement object 5 in a state where the fixing member 8 is pulled in the load direction. Therefore, the load applied to the measurement object 5 can be accurately transmitted to the sensing element 7 via the fixing member 8. Therefore, the initial distortion caused by attaching the fixing member 8 to the measurement object 5 can also be reduced. Therefore, it is possible to further reduce the variation in the output value of the sensing element 7 that occurs for each product.

In addition, since the mounting piece 8b of the fixing member 8 and the step 5s of the measurement object 5 are overlapped and fixed, even if a dimensional tolerance occurs in the direction in which the sensing element 7 detects distortion, The mounting position of the sensing element 7 in the same direction can be adjusted by the mounting piece 8b and mounted on the object 5 to be measured. Therefore, by using the mounting structure according to the present invention, the mounting property of the sensing element 7 can be improved.

In the above-described embodiment, the edge 7e of the sensing element 7 in the direction in which the strain is detected is attached and fixed so as to be in contact with the connecting portion 8c of the fixing member 8. The structure is not limited to the simple structure, and the end 7d of the sensing element 7 is formed only by the pair of legs 8a, 8a of the fixing member 8 without touching the edge 7e of the sensing element 7 and the connecting portion 8c of the fixing member 8. May be fixed. However, the sensing element 7
If the edge 7e of the fixing member 8 is not in contact with the connecting portion 8c of the fixing member 8, the connecting portion 8c of the fixing member 8 is distorted when a load is applied, and is transmitted to the sensing element 7 via the legs 8a. Since an error may occur in the load, it is preferable that the edge of the sensing element 7 and the connecting portion of the fixing member 8 are in contact with each other.

In the above-described embodiment, the end 7d of the sensing element 7 is connected to the pair of legs 8a, 8a of the fixing member 8.
Although the structure for holding and fixing by a is described, the present invention is not limited to this, and the fixing member may have various shapes such as a shape that can be fixed to only one side of the sensing element. it can.

Further, in the above-described embodiment, the case where the sensing element is of the compressive force detecting type has been described. However, in the present invention, since the conventional case assembly is provided with a plurality of fixing members, the sensing element of the shear force detecting type is used. Can also be applied. For example, it is possible to cope with this by adopting a structure in which a longitudinal end portion of the shearing force detection type sensing element is fixed with a fixing member from a direction perpendicular to the longitudinal direction and is attached to a measurement object.

[0032]

As described above, according to the mounting structure of the sensing element according to the first aspect of the present invention, welding can be performed in the same direction as the direction in which strain is detected in the sensing element and the direction of the load applied to the measurement object. Since there will be no gaps between the components,
The sensing element can be attached to the measurement object without the sensing element being pulled in the strain detection direction and the fixing member being pulled in the load direction. Therefore, there is an effect that the initial distortion of the sensing element generated for each product can be reduced due to the dimensional tolerance of the sensing element, the fixing member, and the members of the measurement object.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the contact area between the fixed member and the sensing element can be increased. This has the effect that the load applied to the measurement object can be more accurately transmitted to the sensing element.

According to the mounting structure of the sensing element according to the third aspect of the present invention, in addition to the effects of the first or second aspect, the load is distributed to the pair of legs of the fixed member for sensing. Because it can be transmitted to the element, while reducing the load due to the load of the fixed location,
There is an effect that the sensing element can be fixed in a stable state.

[Brief description of the drawings]

1A and 1B are diagrams showing the arrangement of a measurement object to which the mounting structure of the present invention is applied, wherein FIG. 1A is a partial cross-sectional view, and FIG.

FIG. 2 is a perspective view of a sensing element housed and fixed in the measurement object of FIG. 1;

3A and 3B are views showing a sensing element to which the fixing member of FIG. 1 is fixed, wherein FIG. 3A is a front view and FIG.

FIG. 4 is a sectional view of a mounting structure of the sensing element to a case assembly.

[Explanation of symbols]

 Reference Signs List 5 Measurement object 5h Housing recess 5s Step 7 Sensing element 7d End 7e Edge 8 Fixing member 8a Leg (sensing element fixing part) 8b Mounting piece 8c Connecting part 10 Case assembly

Claims (3)

[Claims] 1. A structure for mounting a sensing element for measuring a load via a case assembly to a receiving recess formed in a measurement object to which a load of a vehicle is applied, wherein the case assembly includes an end of the sensing element. A plurality of fixing members for fixing the portion and the housing concave portion, wherein each of the fixing members is a sensing element fixing portion fixed to an end of the sensing element, and a mounting piece fixed to the measurement object. Wherein the sensing element fixing part is welded to an end of the sensing element so as to intersect a direction in which distortion is detected in the sensing element, and the mounting piece is connected to the sensing element fixing part and an end of the sensing element. A part which is welded to the measured object so as to intersect with the direction of the load applied to the measured object in a state where the portion is fixed. The mounting structure of the element. 2. The mounting structure according to claim 1, wherein an edge of the sensing element in a direction in which distortion is detected is fixed so as to contact the fixing member. 3. The sensing element fixing section has a pair of legs, and the pair of legs is fixed so as to sandwich an end of the sensing element. Or the mounting structure of the sensing element according to 2.