JP3341623B2 - Mounting structure of load sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a load sensor for detecting a load acting on an object to be measured.

[0002]

2. Description of the Related Art Trucks (vehicles) for loading cargo include:
In order to clearly recognize the load, some vehicles have a function of displaying how much load is loaded on the own vehicle. This function uses a load sensor that detects the distortion of the components that make up the truck suspension device, detects the load using the characteristics of the component that is distorted according to the load applied, and displays the result on a display, etc. To display.

[0003] Such a load sensor is required to have high measurement sensitivity. Therefore, a truck is a place where the load is accurately measured, that is, a suspension device that supports the axle on the front wheel side, such as a shackle pin that connects between the end of the leaf spring and the chassis in a leaf spring suspension, In a suspension device that supports the axle on the side, for example, a trunnion type suspension, a trunnion shaft that connects a middle portion of a leaf spring and a chassis is selected, and a load sensor is provided on these components.

In general, as shown in Japanese Utility Model Application Laid-Open No. 6-69759, a shackle pin fitted to a spring bracket mounted on a chassis frame and an eyeball portion of a leaf spring is provided on the front wheel side. 2. Description of the Related Art A sensor mounting hole extending in an axial direction is formed in a (measurement object), and a load sensor is fitted and arranged at a predetermined position in the sensor mounting hole.

On the rear wheel side, a sensor mounting hole extending in the axial direction is formed in a trunnion shaft (measured object) fitted to a trunnion bracket mounted on a chassis frame and a lower saddle for receiving a leaf spring. A load sensor is mounted on a vehicle.

[0006]

A load sensor cannot detect a load unless a distortion follows the displacement of an object to be measured.
In view of the above, the fitting method described above generally employs a method in which a load sensor is press-fitted into a sensor mounting hole and mounted.

However, such a press-fit type certainly has a tight relationship with the load sensor and the inner surface of the sensor mounting hole, that is, the object to be measured. Therefore, when the object to be measured is displaced, it follows the displacement well. In order to stabilize the output, it is required that the fitting tolerance between the sensor mounting hole and the load sensor be set quite tight.

For this reason, in the case of the press-fit type, a considerably large force is required for press-fitting when the load sensor is pressed into the object to be measured and pulling force when the load sensor is withdrawn from the object to be measured. There is a problem that the workability accompanying the attachment / detachment of the load sensor is not good, such as the work of (1) and the work of replacing the load sensor.

In addition, the load sensor in the sensor mounting hole often causes residual strain due to the influence of press-fitting, and there is a problem that sufficient measurement accuracy cannot be obtained. There is a need for a mounting structure for a load sensor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mounting structure of a load sensor capable of easily attaching and detaching a load sensor without causing residual strain. It is in.

[0011]

According to the first aspect of the present invention, when the load sensor is mounted on a workpiece, the load sensor and the opening are located at the entrance of the sensor mounting hole. Insert the holder facing the side and the bolt in this order, and screw the bolt along the large diameter part.

Then, the holder is sent toward the step portion while receiving the axial force of the bolt traveling in the large-diameter portion only at the central portion of the shaft at the axial force transmitting portion. Here, the holder has an opening at the end face on the front side in the insertion direction and forms a space for accommodating the sensor main body. Therefore, the entire load sensor is mounted on the mounting piece while the sensor main body is housed in the space of the holder. Is guided to the step of the sensor mounting hole in such a manner as to be pressed by the holder end.

When reaching the step of the sensor mounting hole, only the mounting piece of the load sensor is pressed against the step by the axial force of the bolt, and is fixed by being sandwiched between the step and the holder. The entire load sensor is fixed while being housed in the section.

The load sensor can be taken out by pulling out the bolt from the sensor mounting hole and taking out the holder. As described above, since the attaching / detaching operation of the load sensor can be performed by a simple operation that does not require a large force such as turning a bolt, the attaching / detaching of the load sensor can be easily performed. Particularly, by fixing the load sensor using the step portion, the load sensor is positioned at a predetermined position in the axial direction of the sensor mounting hole, so that the load sensor can be easily mounted on the target sensor mounting hole in the axial direction. .

Further, at the time of assembly, the pressing force from the bolt is:
Until the load sensor is fixed by the holder, the load sensor is acted only on the mounting piece without acting on the sensor main body, so that the occurrence of residual distortion of the sensor main body due to the influence of the axial force of the bolt is suppressed.

In addition, since the pressing force from the bolt is applied only to the center of the shaft of the holder, the torsional force when rotating the bolt is not transmitted to the holder, and the residual force due to the torsional torque is not transmitted. The distortion does not need to act on the load sensor.

In the mounting structure of the load sensor according to the present invention, when a bending load is applied to the workpiece after the mounting of the load sensor, a bending stress is generated in the bolt. At this time, the load sensor is fixed. Since the holder and the bolt are only in contact with each other at the spherical portion, the stress is released by sliding of the spherical surface of the spherical portion.

Thus, the pressing force fixing each mounting piece of the load sensor does not need to be affected, and the load sensor
High measurement accuracy can be maintained by avoiding the influence of the bolt.

In the load mounting structure according to the third aspect, when the holder, in which the load sensor is held in a predetermined position, reaches the step of the sensor mounting hole, the engaging portion for preventing the holder from rotating is formed by the step. The load sensor is positioned and fixed at a predetermined position in the circumferential direction of the sensor mounting hole by engaging with the engagement receiving portion for regulating the rotation of the portion, so that the mounting accuracy of the load sensor in the high circumferential direction of the sensor mounting hole is high. Is obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS. FIG. 1 shows a vehicle to which the present invention is applied, for example, a rear two-axle truck.
Is a chassis frame, 2 is a cab, and 3 is a carrier.

The front wheels 4 of the truck are suspended by a suspension device, for example, a leaf-type spring suspension 5. More specifically, front and rear ends of a leaf spring 6 extending in the vehicle front-rear direction are supported by a spring bracket 9 mounted on the chassis frame 1 using components such as a shackle pin 7 and a shackle link 8 to hold the front wheel 4. The front axle 10 is supported. In addition, 11 shows a shock absorber.

The rear / front wheel 15 and the rear / rear wheel 16 are provided with a suspension device, for example, a trunnion type suspension 1.
It is suspended at 7. Specifically, an intermediate portion of the leaf spring 18 extending in the vehicle front-rear direction is supported by a trunnion bracket 21 installed on the chassis frame 1 via a U-shaped spring fixture 19a, a lower saddle 19, and a trunnion shaft 20. , A rear axle 22 holding the rear / front wheels 15 and the rear / rear wheels 16 is supported.

Each of the front and rear wheel-side suspension devices is provided with a load sensor, for example, a compression type magnetostrictive sensor 26 which is a main part of the present invention and detects a load applied to the axle.

Specifically, on the front wheel side, for example, a spring bracket 9 is fitted as a place where good load measurement can be expected from each part of the leaf-type spring suspension 5 supporting the front wheel 4, and the leaf spring 6 is fitted in the middle part. The shackle pin 7 on the front side of the vehicle, into which the eyeball portion 6a is fitted, is selected as an object to be measured, and a magnetostrictive sensor 26 is provided inside the shackle pin 7.

On the rear wheel side, for example, the trunnion bracket 21 can be used as a place where good load measurement can be expected from each part of the trunnion type suspension 17 supporting the rear two wheels.
A trunnion shaft 20 fitted with a lower saddle 19 supporting the leaf spring 18 at the other end.
Is selected as an object to be measured, and a magnetostrictive sensor 26 is provided inside the trunnion shaft 20.

The front and rear wheel side magnetostrictive sensors 2
The load applied from the front and rear sides of the chassis frame 1 is detected by the distortion of the shackle pin 7 and the trunnion shaft 20 detected at 6.

Here, for mounting the magnetostrictive sensor 26 on the trunnion shaft side, a mounting structure which is a main part of the present invention is adopted. FIG. 2 shows the mounting structure of the magnetostrictive sensor 26, and FIGS. 3 and 4 show the detailed structure of each part thereof.

The mounting structure of the magnetostrictive sensor 26 will be described.
As shown in FIGS. 3A, 3B and 4, a sensor mounting hole 28 extending from the end face along the axial direction is formed.

The sensor mounting hole 28 has a large-diameter portion 28a formed on the entrance side and a small-diameter portion 28b formed on the back side with the step portion 25 serving as a sensor mounting portion interposed therebetween. Step 2
As shown in FIG. 4, a pair of positioning grooves 25b (corresponding to the engagement receiving portions of the present application) are formed in the side surface 25a of the fifth device 5 as shown in FIG. For example, an internal thread 29 is formed on the inner surface of the large diameter portion 28a except for the vicinity of the step portion 25.

In the sensor mounting hole 28, the magnetostrictive sensor 26
Is inserted. The sensor body 30 of the magnetostrictive sensor 26 includes:
As shown in FIG. 4, the plate surface is of a vertical type in which the sensor mounting hole 28 is oriented in the axial direction, and is formed of, for example, a magnetostrictive material (a magnetic material such as permalloy) and four small holes 31 are provided in the cross direction. It has a thin sensor plate 32, a drive coil 33 and a detection coil 34 wound between the small holes 31 in a cross shape. Further, a pair of mounting pieces 35 protrude from the upper and lower portions of the sensor main body 30 in the vertical direction, which is the outer peripheral direction, respectively.

This magnetostrictive sensor 26 is
The sensor body 30 is free by the holder 36 and the bolt 37 inserted into the large-diameter portion 25 of the sensor mounting hole 28, and specifically, a pair of upper and lower mounting portions so as to be loosely fitted into the large- and small-diameter portions 28a and 28b. Only the piece 35 is seated and fixed on the side surface 25 a of the step 25.

Specifically, as shown in FIG. 4, the holder 36 has a bottomed cylindrical main body 39 having a flange portion 38 formed at an open end. The main body 39 is inserted into the large-diameter portion 28a with the open end facing the step portion 25.

The size of the flange portion 38 is determined so as to press only the mounting piece 35 of the magnetostrictive sensor 26.
The internal cylindrical space 40 that is continuous from the opening end of the main body 39 is sized to accommodate the sensor main body 30 of the magnetostrictive sensor 26 (the inner diameter is larger than the radial length of the sensor main body 30). When the holder 36 is inserted toward the step 25, only the mounting piece 35 can be pressed against the side surface 25 a of the step 25 by the flange 38 without touching the sensor body 30. That is, the holder 36 is
In cooperation therewith, only the mounting piece 35 can be pressed and held.

At the front end (open end) of the flange portion 36a,
A pair of upper and lower sensor holding grooves 41 (corresponding to the groove portion in the present application) are formed in the upper and lower direction for accommodating the respective mounting pieces 35 of the magnetostrictive sensor 26, and only the mounting pieces 35 are held. So that the entire magnetostrictive sensor can be held while being loosely fitted.

The depth dimension of the sensor holding groove 41 is formed smaller than the width dimension of the mounting piece 35, and does not hinder the pressing and holding of the mounting piece 35 performed in cooperation with the step 25.
Further, at the front end (open end) of the flange portion 36a, for example, a pair of protrusions 42 (corresponding to the engagement portions of the present application) for preventing rotation are provided in a horizontal direction orthogonal to the sensor holding groove 41. The outer shape of each projection 42 is set to a size that can fit in the positioning groove 25b, and the magnetostrictive sensor 26 held in the sensor holding groove 41 is used for positioning by fitting the projection 42 into the positioning groove 25b. Each mounting piece 35 is positioned in a posture suitable for a predetermined measurement, that is, a posture in which a load is applied from the trunnion shaft 20 (here, a vertical direction).

A spherical projection 43 protrudes from the center of the outer surface of the bottom wall of the main body 39, more specifically, from the axial center of the outer surface. On the other hand, as shown in FIGS.
Has, for example, a short-column-shaped main body 45 in which a screw 44 that can be screwed into the female screw 29 of the large-diameter portion 28a is formed on the outer peripheral portion. The main body 45 is a large diameter portion 28a of the sensor mounting hole 28.
Is screwed into.

A hexagonal bolt head portion 47 operated by a head 46 of, for example, a bolt operating tool or device is provided at an end of the main body 45 facing the entrance side (an end on the rear side in the insertion direction).
By rotating the bolt head portion 47 with the head 46, the bolt 37 can be advanced to the deep portion of the sensor mounting hole 28 and, conversely, can be pulled out to the entrance side.

In the center of the end of the main body 45 facing the holder 36 (the end on the front side in the insertion direction), more specifically, at the center of the shaft, a spherical receiving surface 48 slidably receives the spherical projection 43 of the holder 36. Is also equivalent to the spherical part) is formed,
The pressing force from the bolt 36 is applied to the spherical projection 43 and the spherical receiving surface 4.
8 is applied only to the central portion of the shaft of the holder 36 via a ball joint 49 (corresponding to an axial force transmitting portion of the present application) formed by contact with the shaft 8.

The trunnion shaft 20 is formed by a ball joint 49 formed by the spherical projection 43 and the spherical receiving surface 47.
The bending stress of the bolt 37 caused by the bending is released. Specifically, the bending stress of the bolt 37 is released by slippage between the spherical surface of the spherical projection 43 and the spherical receiving surface 48,
It is not transmitted to the holder 36.

With such a structure, the magnetostrictive sensor 26 is
The trunnion shaft 2 can be easily formed without generating residual stress.
0 (measurement object). That is, when attaching the magnetostrictive sensor 26 to the trunnion shaft 20, for example, first, as shown in FIG. 3B, the magnetostrictive sensor 26 is assembled at the tip of the holder 37.
Specifically, the sensor body 3 is placed in the space 46 of the holder 37.
The respective mounting pieces 35 are fitted into the respective sensor holding grooves 41 while the rear side in the width direction of 0 is housed, and the entire magnetostrictive sensor 26 is assembled in a posture in which the plate surface faces the axial direction of the holder 37.

The holder 37 is inserted into the entrance of the sensor mounting hole 28 using the flange 38 as an insertion guide, with the projection 42 facing the horizontal direction from the distal end holding the magnetostrictive sensor 26. Thereby, the magnetostrictive sensor 2
6. The holder 37 is inserted into the sensor mounting hole 28 in the order of the opening (the opening is directed toward the back).

Finally, the bolt 37 is inserted into the entrance of the sensor mounting hole 28 using a head 46 such as a bolt operating tool or equipment, and is screwed in according to the female screw 29 of the large diameter portion 28a.

Then, the holder 37 is fed toward the step portion 25 while receiving only the spherical force of the bolt 37 traveling in the large diameter portion 28a at the spherical projection 43, that is, the shaft center portion. Thereby, the magnetostrictive sensor 26 is guided to the step portion 25 while maintaining the posture at the time of insertion so that only the mounting piece 35 is pushed by the holder end while the sensor main body 30 is housed in the space portion 40 of the holder 36. I will

When approaching the step portion 25, the front side in the width direction of the sensor body 30 protruding from the opening of the holder 37 becomes the small diameter portion 2.
8b begins to enter. Subsequently, each of the protrusions 42 for preventing rotation of the tip of the holder is fitted into each of the positioning grooves 25b (for rotation regulation) on the side surface 25a of the step portion 25, and the magnetostrictive sensor 26
Is defined as a predetermined position in the circumferential direction of the sensor mounting hole 28, that is, a posture in which the pair of mounting pieces 35 face in the vertical direction.

In this state, each mounting piece 35 of the magnetostrictive sensor 26 is gradually pressed against the side surface 25 a of the step 25 by the pressing force applied from the bolt 37. On this occasion,
The reaction force acting on the holder 36 causes the holder 36 to bend together with the bolt 37. However, the co-rotation is restricted by the engagement between the projection 42 and the positioning groove 25b. Does not rotate.

As a result, the magnetostrictive sensor 26 is configured such that only the mounting piece 35 is
And the holder 36 is fixed.
When the tightening with the bolts 36 is completed, as shown in FIG. 3A, the entire magnetostrictive sensor 26 is mounted on the stepped portion 2 with the sensor main body 30 loosely fitted in the space 46 of the holder 36.
5 is installed.

When taking out the magnetostrictive sensor 26,
The opposite operation, that is, pulling out the bolt 37 from the sensor mounting hole 28, and then pulling out the holder 36 is sufficient. Thus,
Since the attaching and detaching work of the magnetostrictive sensor 26 (load sensor) can be performed by a simple operation that does not require a large force such as turning a bolt, the attaching and detaching of the magnetostrictive sensor 26 can be easily performed. Provides good workability in work. In particular, the magnetostrictive sensor 2 using the step 25
In the structure for fixing the sensor mounting hole 6, the sensor mounting hole 28 is positioned in the axial direction, so that the magnetostrictive sensor 26 can be easily mounted on the target axial mounting portion of the sensor mounting hole 28, that is, the target sensor mounting portion. .

In addition, at the time of assembly, the pressing force from the bolt 37 is applied only to the mounting piece 35 without acting on the sensor body 30 until the magnetostrictive sensor 26 is fixed by the holder 36. There is no residual distortion of the sensor body 30 due to the influence of the axial force of the bolt 37.

In addition, the pressing force from the bolt 37 is
Since it is applied only to the shaft center of the holder 36, the holder 3
The torsion force when rotating the bolt 37 is not transmitted to 6, and the residual strain due to the torsion torque does not act on the magnetostrictive sensor 26.

Therefore, the magnetostrictive sensor 26 can be easily attached to and detached from the shackle pin 7, which is the object to be measured, without causing residual strain. Moreover, the magnetostrictive sensor 26 is provided on the front end face of the holder 36.
Of the magnetostrictive sensor 26 is defined by a rotation preventing projection 42 provided on the front end face of the holder 36 and a positioning groove 25b provided in the step portion 25. Therefore, high mounting accuracy in the circumferential direction of the sensor mounting hole 28 can be obtained.

Further, a structure for applying a pressing force only to the shaft center of the holder 36 is formed by a spherical projection 43 and a spherical receiving surface 48.
And the bending load acts on the trunnion shaft 20 (measurement object) on which the magnetostrictive sensor 26 has been mounted.
Even if bending stress is applied to the bolt 37, the bolt 3 may slip due to the sliding of the spherical surface of the spherical portion between the holder 36 and the bolt 37.
Since the bending stress of No. 7 escapes, the stress does not have to affect the pressing force fixing the mounting pieces 35 of the magnetostrictive sensor 26.

That is, the effect of the bolt 37 is avoided in the magnetostrictive sensor 26, so that high measurement accuracy is maintained.
Due to this increase in precision, the magnetostrictive sensor 26 attached to the shackle pin 7 and the magnetostrictive sensor 26 attached to the trunnion shaft 20 as shown in FIG.
The load applied to the axle of the front wheel 4 and the load applied to the axles of the rear two wheels 15 and 16 are connected to the display 51 via the load (the load applied to the axle weight of the front wheel 4 and the load applied to the axle of the rear two wheels). With the device that displays the sum, a high measurement result is obtained, so that the loaded load can be correctly known.

In one embodiment, the spherical projection 43 and the spherical receiving surface 48 formed integrally with the holder 36 and the bolt 37 are provided.
However, the present invention is not limited to this. For example, as in another embodiment shown in FIG. 5A, a receiving surface member 60 having a spherical receiving surface 48 is separately provided at the center of the front end of the bolt 37 (axial center portion). 5), a spherical portion 61 is formed in the center (axial portion) of the rear surface of the holder 36 as in another embodiment shown in FIG. 5B, and the spherical portion 61 and the spherical receiving surface 48 are formed. May be interposed between the spheres 63 (in this case, the sphere 63
Is preliminarily rotatably assembled to one of the spherical portion 61 and the spherical receiving surface 48), and has the same effect. Therefore, the structure of the axial force transmitting portion is not limited.

Further, in one embodiment, the example in which the magnetostrictive sensor 26 is assembled to the trunnion shaft 20 has been described. However, the present invention is not limited to this, and the present invention can be applied to a front suspension, specifically, for example, as shown in FIG. Alternatively, the magnetostrictive sensor 26 may be attached to the shackle pin 7 for supporting the eyeball portion 6a of the sixth bracket on the spring bracket 9. In FIG. 6, the same portions as those of the embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In the above embodiment, an example in which the magnetostrictive sensor is applied has been described. However, the present invention is not limited to this, and a load sensor having another type, another system, or another structure may be used. Further, in one embodiment, the present invention is applied to a structure for detecting the load of a truck. However, it is needless to say that the present invention is not limited to a vehicle-mounted type and may be applied to a structure in which a load sensor is mounted for other uses. Of course, the shape of the holder 36 and the shape of the bolt 37 may be other shapes. For example, the protrusion 42 may be formed on the step 25 and the positioning groove 25b may be formed on the holder 36. Further, the projection 42 (engaging portion) and the positioning groove 25b (engaging receiving portion) may not be provided. For example, as in the other embodiment shown in FIG. 7, the protrusion 42 (engaging portion), the positioning groove 25b
Even if the load sensor is attached using a plate-like holder 36 employing a substantially U-shaped main body 39 so that the positioning by the (engagement receiving portion) becomes unnecessary, the same effect as in the embodiment can be obtained. Play. In FIG. 7, the same reference numerals are given to the same parts as in the embodiment, and the description thereof is omitted.

[0056]

As described above, according to the first aspect of the present invention, the load sensor can be easily fixed to the step portion of the sensor mounting hole by a simple operation that does not require a large force such as turning a bolt. . Moreover, at the time of the assembling operation, the pressing force from the bolt acts only on the shaft center portion of the holder by the shaft transmitting portion, and the torsion torque from the bolt does not need to be transmitted to the holder.

Therefore, unlike the press-fit type, the load sensor can be easily installed in the sensor mounting hole without causing residual strain. In addition, since the step portion positions the sensor mounting hole of the load sensor in the axial direction, the load sensor can be easily attached to a target portion.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in the above, since the bending stress acting on the bolt escapes due to the sliding of the spherical surface of the spherical portion, the pressing force of each mounting piece of the load sensor does not have the effect of unnecessary stress,
The load sensor can always maintain high measurement accuracy.

According to the third aspect of the present invention, the first aspect
In addition to the effects of the invention described in (1), since the load sensor is positioned and fixed at a predetermined position in the circumferential direction of the sensor mounting hole, mounting accuracy of the load sensor in the circumferential direction of the sensor mounting hole can be expected.

[Brief description of the drawings]

FIG. 1 is a view showing a truck (vehicle) to which a load sensor mounting structure according to an embodiment of the present invention is applied;

FIG. 2 is an enlarged cross-sectional view around the trunnion shaft along the line AA in FIG. 1;

FIG. 3 is a cross-sectional view for explaining in detail a structure around a magnetostrictive sensor in a portion C in FIG. 2;

FIG. 4 is a partially sectional perspective view showing the entire structure of the same structure.

FIG. 5 is a cross-sectional view for explaining a main part of another different embodiment.

FIG. 6 is a sectional view taken along the line BB in FIG. 1 for explaining an example in which a magnetostrictive sensor is attached to a shackle pin according to another embodiment.

FIG. 7 is a perspective view illustrating another embodiment using holders having different shapes.

[Explanation of symbols]

Reference Signs List 20 trunnion shaft (measured object) 25 step 25b positioning groove (engagement receiving part) 26 magnetostrictive sensor (load sensor) 28 sensor mounting hole 28a large diameter part 28b small diameter part 30 sensor body 35 Mounting piece 36 Holder 37 Bolt 41 Sensor holding groove (groove) 42 Projection (engaging portion) 43, 48 Spherical projection, spherical receiving surface (spherical portion, axial force transmitting portion) 46 Space.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-313740 (JP, A) JP-A-8-285667 (JP, A) JP-A-8-313332 (JP, A) JP-A-10-108 253468 (JP, A) JP 6-69758 (JP, U) JP 4-50970 (JP, B2) Patent 3102327 (JP, B2) Patent 3109723 (JP, B2) Patent 3001153 (JP, B2) New model registration 2595579 (JP, Y2) Utility model registration 2598378 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01G 19/08 G01G 19/12

Claims (3)

(57) [Claims] 1. A sensor mounting hole provided on a measurement object, having a large-diameter portion formed on an inlet side and a small-diameter portion formed on an inner side of a step portion, a sensor main body for detecting a load, and an outer periphery from the sensor main body. A load sensor having a mounting piece protruding in the direction and housed in the sensor mounting hole, and a space portion that is open to the end surface on the step side side and houses the sensor body is provided, and is provided in the large-diameter portion. A holder which is inserted and cooperates with the step portion to hold the mounting piece; and a bolt which is screwed to the large diameter portion and provided so as to press and fix the mounting piece to the step portion via the holder. An axial force transmitting unit provided between the bolt and the holder, the axial force transmitting unit applying an axial force of the bolt only to an axial center portion of the holder. 2. The load sensor mounting structure according to claim 1, wherein the axial force transmitting portion is formed so that the bolt side and the holder side abut via a spherical portion. 3. A groove for accommodating the mounting piece and an engaging portion for preventing rotation are formed on the step-side end surface of the holder, and the sensor mounting hole is engaged with the engaging portion. The mounting structure of the load sensor according to claim 1, further comprising an engagement receiving portion that restricts rotation of the holder.