JP3219015B2 - Load detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detecting device for detecting a load applied from an upper member to a lower member via a shaft member from a strain generated in the shaft member.

[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. For this function, a load detection device using a load sensor that detects the distortion of the components that make up the truck suspension device is adopted, and the same load is detected using the characteristics of the component that is distorted according to the load applied, The result is displayed on a display or the like.

Incidentally, a load detecting device is required to have high measurement sensitivity in order to obtain an accurate load. Therefore,
A truck is a suspension device that supports the front axle, such as a shackle pin that connects between the end of the leaf spring and the chassis. In a device, 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.

Specifically, as shown in Japanese Utility Model Laid-Open No. 6-69759, when the front wheel is used, a spring bracket (upper member) to which a load is applied and an end of a leaf spring to which the load is applied are provided. A sensor mounting hole extending in the axial direction is formed in the fitted shackle pin (shaft member), and a load sensor is provided in a portion of the sensor mounting hole corresponding to a gap between the spring bracket and the end of the leaf spring. Installation has been done.

On the rear wheel side, a sensor mounting hole extending in the axial direction is formed in a trunnion shaft (shaft member) fitted to a trunnion bracket (upper member) to which a load is applied and a lower saddle to which the load is applied. Then, a load sensor is mounted on a portion of the sensor mounting hole corresponding to a gap between the trunnion bracket and the lower saddle.

[0006]

As a result of various experiments, the present applicant has found that a load is applied from an upper member fitted to a shaft member to a lower member also fitted to the shaft member. , A large shear stress is generated in the shaft member obliquely downward from the gap between the upper portion of the outer peripheral top and the lower member.

However, in the conventional load detecting device, the load sensor is disposed at a position corresponding to a gap between the spring bracket and the trunnion bracket as the upper member and the end of the leaf spring and the lower saddle as the lower member. Since the sensor is mounted at a position far away from the portion where the stress increases, sufficient sensitivity should be obtained, but in practice, sufficient sensitivity was not obtained.

For this reason, there is a demand for a load detecting device that ensures sufficient measurement sensitivity based on knowledge. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a load detection device capable of improving the sensitivity of a load sensor without changing the detection structure of the sensor.

[0009]

According to a first aspect of the present invention, there is provided a load detecting device, wherein a load sensor applies a load to a shaft member from an upper member to a lower member via the shaft member. The shaft member is disposed near the portion where the stress increases obliquely downward from the gap between the upper member and the lower member at the top of the outer periphery of the shaft member. In addition, since the pair of upper and lower mounting pieces for mounting the load sensor are mounted on the shaft member in a direction following the stress direction obliquely downward,
The generated stress is easily input to the load sensor via the mounting piece as it is. That is, the load sensor reacts sensitively.

As a result, the strain generated in the shaft member can be most effectively detected by the load sensor, and high measurement sensitivity of the load sensor can be expected only by the sensor mounting structure without changing the sensor itself. Become like

In the load detecting device according to the second aspect, when assembling the load sensor to the shaft member, the load sensor is moved until the pair of upper and lower mounting pieces come into contact with the side surfaces of the pair of mounting steps. After inserting from the sensor mounting hole, simply attach each mounting piece to the side surface of the mounting step, the load sensor is
It is reliably positioned and mounted in a sensitive location.

In the load detecting device according to the third aspect, the entire load sensor including the mounting piece and the mounting step is disposed at a position where the stress acting on the shaft member is the maximum and in the direction of the stress in which the maximum stress is generated. Therefore, higher measurement sensitivity can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to 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.

A rear / front wheel 15 and a 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 longitudinal direction is a lower saddle 19,
Through the trunnion shaft 20, the chassis frame 1
The rear axle 17 is supported by a trunnion bracket 21 installed on the rear axle 17 and holds the rear and front wheels 15 and the rear and rear wheels 16.

Each of the front and rear wheel suspension devices is provided with a load detecting device 25 which detects a load applied to the axle, which is a main part of the present invention. Specifically, the load detection device 25 on the front wheel side is provided with fork ends at both ends as shown in FIG. 2 as places where good load measurement can be expected from each part of the leaf-type spring suspension 5 supporting the front wheel 4. Spring bracket 9 (corresponding to the upper member of the present application) is fitted, and the center portion 6b of the leaf spring 6 is connected to the intermediate portion via the bush 6a.
A shackle pin 7 (corresponding to a shaft member according to the present invention) on the front side of the vehicle to which the lower member (corresponding to a lower member according to the present application) is fitted is selected, and a load sensor for detecting the strain of the shackle pin 7 is used. A magnetostrictive sensor 26 is provided to detect the load applied from above the chassis frame 1 from the strain of the shackle pin 7.

Further, the load detecting device 25 on the rear wheel side is provided from each part of the trunnion type suspension 17 supporting the rear two wheels,
As a place where good load measurement can be expected, for example, as shown in FIG.
(Corresponding to an upper member of the present application), and a trunnion shaft 20 fitted with a lower saddle 19 (corresponding to a lower member of the present application) supporting the leaf spring 18 at the other end.
(Corresponding to the shaft member of the present application), and a load sensor for detecting the strain of the trunnion shaft 20 on the trunnion shaft 20;
For example, a compression type magnetostrictive sensor 27 is provided to apply a load applied from above the chassis frame 1 to the trunnion shaft 20.
Is detected from the distortion.

As a result of various experiments by the present applicant, when a load is applied from the upper member fitted to the shaft member to the lower member similarly fitted to the shaft member, Based on the knowledge that a large shear stress is generated diagonally downward from the gap between the upper part and the lower part at the top of the outer periphery of the member, a device for increasing the sensitivity of each of the magnetostrictive sensors 26 and 27, specifically, The sensor mounting structure has been improved. The mounting structure of the magnetostrictive sensors 26 and 27 is
Since both are the same, only the mounting structure of the magnetostrictive sensor 26 will be described.

The mounting structure of the magnetostrictive sensor 26 is shown in FIGS. Here, the mounting structure of the magnetostrictive sensor 26 will be described. For example, as shown in FIGS. 2 (a) to 2 (c), a sensor mounting hole extending in the axial direction from the end face in the axial center of the shackle pin 7. 28 are drilled.

In this sensor mounting hole 28, a pair of upper and lower mounting steps 29a, 29b is provided at a position offset in the axial direction from a gap L on one side between the spring bracket 9 and the eyeball 6b at the top of the outer periphery of the shackle pin 7. Is provided.

More specifically, the mounting step 29a on the upper side is axially offset from the gap L at the top of the outer periphery of the pin by using a step formed at this time by changing the sensor mounting hole 28 to a small diameter in the middle. It is formed at the point. Further, the lower mounting step 29b is formed at a point offset in the axial direction from the mounting step 29a by further forming a step on the side surface.

With this offset structure, each mounting step 2
9a, 29b, the sensor mounting surfaces 30a,
30b, a path in which a shear stress generated when a load is applied from the spring bracket 9 to the leaf spring 6 is directed obliquely downward from a gap L between the spring bracket 9 and the eyeball portion 6b at the outer peripheral top of the shackle pin 7;
That is, they are arranged near the main stress generation path indicated by the virtual line δ.

Preferably, when a load is applied from the spring bracket 9, the shear stress directed obliquely downward from the gap L at the top of the outer periphery of the pin is likely to occur mainly along the path of the virtual line δ directed obliquely downward at 45 degrees. It is desirable to dispose a pair of upper and lower sensor installation surfaces 30a and 30b near the virtual line δ.

Using the sensor installation surfaces 30a and 30b, the compression type magnetostrictive sensor 26 is installed along the virtual line δ. That is, the main body of the magnetostrictive sensor 26 is formed of, for example, a magnetostrictive material (a magnetic material such as permalloy),
A thin sensor plate 34 in which four small holes 33 are provided in the cross direction, and a driving coil 3 in which the small holes 33 are wound in a cross shape.
5 and a detection coil 36.

From the upper and lower portions of the sensor plate 34, a pair of mounting pieces 38a and 38b protrude in the vertical direction, respectively, and the lower mounting piece 38b is more closely spaced than the upper mounting piece 38a. It is offset along the axial direction of the sensor mounting hole 28 so as to be far from the portion L.

The mounting piece 38a on the upper side of the magnetostrictive sensor 26 has, for example, a sensor mounting hole 2 as shown in FIG.
8 is joined to the upper sensor mounting surface 30a using the laser welding light incident from the entrance, and the lower mounting piece 38b is similarly connected to the lower sensor mounting surface 30b using the laser welding light. And the entire magnetostrictive sensor 26 is
At a point near the imaginary line δ (the portion where the shear stress increases: the main stress direction), the camera is attached in a diagonally downward orientation following the imaginary line δ. In addition, X shows a welding location.

By attaching the magnetostrictive sensor 26, the load applied to the leaf spring 6 from the chassis frame 1 via the shackle pin 7 can be detected with high accuracy.

That is, it is assumed that cargo is loaded on the truck bed 3. Then, the load of the cargo is transferred from the chassis frame 1 to the spring bracket 9 and the shackle pin 7.
, And transmitted to the eyeball portion 6b of the leaf spring 6.

At this time, due to the load applied to the shackle pin 7 from above, a shear stress is generated in the pin portion between the spring bracket 9 and the eyeball portion 6b. Then, a tensile force or a compressive force at this time is applied to the magnetostrictive sensor 26, the magnetic permeability of the magnetic material changes, and a current proportional to the applied force is output from the detection coil 36 to detect the load.

At this time, the present applicant has determined from various experiments that
A large shear stress is generated not in a direction directly below the gap L at the outer periphery top of the shackle pin 7 but in a direction obliquely downward from the gap L as shown by a virtual line δ in FIG. With the knowledge.

Here, the compression type magnetostrictive sensor 26 follows the imaginary line δ near a portion where a large shear stress is caused by a structure in which the pair of upper and lower mounting pieces 38a and 38b are offset obliquely downward from the gap L. Since the sensor plate 34 is mounted in the orientation, the distortion caused by the large shear stress is input to the sensor plate 34 through the mounting pieces 38a and 38b from the direction of the main stress generation path.

As a result, the magnetostrictive sensor 26 responds sensitively to the applied load. That is, the sensitivity of the magnetostrictive sensor 26 can be increased, and high measurement sensitivity can be obtained only by the sensor mounting structure without changing the detection structure of the sensor. In particular, when the mounting pieces 38a and 38b of the magnetostrictive sensor 26 are arranged near the imaginary line δ which goes obliquely 45 degrees from the gap L at the top of the outer periphery of the pin, the shear stress acting on the shackle pin 7 is the largest and the largest stress is Since the magnetostrictive sensor 26 is attached at a point in the direction of the generated stress, higher measurement sensitivity can be expected.

Of course, the same applies to the magnetostrictive sensor 27 provided on the trunnion shaft 20 (FIG. 4). Therefore, the applied load can be detected with high accuracy from the distortion of the shaft members such as the shackle pin 7 and the trunnion shaft 20 by the magnetostrictive sensor 26.

This means that the magnetostrictive sensor 26 attached to the shackle pin 7 and the magnetostrictive sensor 27 attached to the trunnion shaft 20 as shown in FIG. A device that displays the loaded load (sum of the load applied to the front wheel 4 axle load and the load applied to the rear two axle load) from the load applied to the axle load of the front wheel 4 and the load applied to the axle load of the rear two wheels, High measurement results can be obtained.

Moreover, a pair of upper and lower sensor mounting surfaces 30a, 30b offset in the sensor mounting hole 28 are formed in correspondence with the pair of upper and lower mounting pieces 38a, 38b of the magnetostrictive sensor 26 which are offset. In addition, the magnetostrictive sensor 26 can be securely attached to a location with good sensitivity.

That is, when assembling the magnetostrictive sensor 26 to the shackle pin 7 (or the trunnion shaft 20), the magnetostrictive sensor 26 is inserted from the entrance end of the sensor mounting hole 28, and the offset mounting pieces 38a and 38b are
The sensor mounting surface 30 of the displaced mounting step portions 29a, 29b
The sensor mounting hole 28 can be positioned in the axial direction only by inserting the sensor mounting hole 28 until the sensor mounting hole 28 comes into contact with the a and 30b. After the positioning, the mounting pieces 38a and 38b are connected to the sensor mounting surface 30.
This is because the magnetostrictive sensor 26 can be securely attached to a place where the stress is increased simply by joining the magnetostrictive sensors 26a and 30b.

In particular, the structure in which the magnetostrictive sensor 26 is fixed by laser welding is different from press-fitting and fixing the sensor in the process from insertion into the sensor mounting hole 28 to fixing. Since no external force is applied in the direction, high accuracy can be expected from the beginning (in the case of the press-fit type, it is necessary to apply a customary load at the beginning). Moreover, unlike the press-fit type, there is no need for a press-fitting device, and there is no need for high-precision drilling for press-fitting.
The equipment required for mounting the magnetostrictive sensor 26 is simple.

In one embodiment, the mounting pieces 38a and 38b of the magnetostrictive sensor 26 are offset toward the center of the shaft pin 7 and the center of the trunnion shaft 20. Shaft pin 7
The same effect can be obtained by offsetting the end face side of the trunnion shaft 20 to the end face side.

Further, in one embodiment, an example in which a magnetostrictive sensor is applied has been described. However, the present invention is not limited to this, and another load sensor may be used. In one embodiment, the present invention is applied to a structure for detecting the load of a truck. However, the present invention is not limited to this, and a load detection device having a structure for applying a load from an upper member to a lower member via another shaft member. Of course, it may be applied to.

[0040]

As described above, according to the first aspect of the present invention, since the load sensor is mounted near the portion where a large stress is applied and in a posture following the direction of the stress, the stress sensor is mounted from the stress generation path. Can be easily input to the load sensor via the mounting piece.

As a result, since the load sensor responds sensitively to the applied load, the sensitivity of the load sensor can be increased, and the measurement sensitivity can be reduced only by the sensor mounting structure without changing the sensor detection structure. Improvement can be achieved.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in the above, a pair of upper and lower offset mounting pieces of the load sensor are simply inserted into the sensor mounting hole until they come into contact with the side surfaces of the upper and lower mounting step portions, and the shaft until the stress becomes large is increased. Since the positioning in the direction can be performed, the load sensor can be surely attached to a place having high sensitivity.

According to the invention described in claim 3, according to claim 1
In addition to the effects of the invention described in (1), the entire load sensor, including the mounting piece and the mounting step, is disposed at a position where the stress acting on the shaft member is the maximum and the stress is in the stress direction in which the maximum stress occurs. And higher measurement sensitivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a truck (vehicle) to which a load detection device according to an embodiment of the present invention is applied.

FIG. 2 is a view for explaining a structure in which a magnetostrictive sensor (load sensor) is attached to a portion of the shackle pin constituting the front suspension of the truck where a large stress is generated.

FIG. 3 is a perspective view for explaining a mounting structure of the magnetostrictive sensor in detail.

FIG. 4 is a diagram for explaining a structure in which a magnetostrictive sensor (load sensor) is attached to a portion of a trunnion shaft that forms a rear suspension of a truck where a large stress is generated.

[Description of References] 7, 20: Shackle pin, trunnion shaft (shaft member) 9, 21: Spring bracket, trunnion bracket (upper member) 6b, 19: Eyeball portion of leaf spring, lower saddle (lower member) 26, 27 ... Magnetostrictive sensor (load sensor) 28 ... Sensor mounting holes 29a, 29b ... Mounting steps 30a, 30b ... Sensor mounting surface (side face of mounting steps) 38a, 38b ... A pair of upper and lower mounting pieces L ... Gap part at pin outer peripheral top δ ... virtual lines.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-102692 (JP, A) JP-A-6-313740 (JP, A) JP-A 8-313332 (JP, A) JP-A 8- 254456 (JP, A) Japanese Utility Model Application Hei 6-69759 (JP, U) West German Patent Application Publication 3429348 (DE, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 1/12 G01G 19 / 12

Claims (3)

(57) [Claims] 1. A sensor mounting hole is formed in an axial direction of a shaft member which is fitted to an upper member to which a load is applied and a lower member which receives the load and applies a load from the upper member to the lower member. In a load detection device having a load sensor for detecting distortion of the shaft member mounted in the sensor mounting hole, the load sensor is disposed so as to be offset in the axial direction from a gap between the upper member and the lower member. ,
The load sensor is attached to the shaft member via a pair of upper and lower mounting pieces provided on the load sensor and projecting in the vertical direction, and the lower mounting piece is farther in the axial direction from the gap than the upper mounting piece. A load detection device characterized by being arranged. 2. The sensor mounting hole has a pair of mounting steps formed corresponding to the pair of mounting pieces, and each of the mounting pieces is joined to a side surface of each of the mounting steps. The load detection device according to claim 1, wherein: 3. The load according to claim 1, wherein the pair of upper and lower mounting pieces are arranged near an imaginary line extending obliquely downward at 45 degrees from the gap portion at the outer peripheral top of the shaft member. Detection device.