WO2019026655A1

WO2019026655A1 - Load cell and bearing

Info

Publication number: WO2019026655A1
Application number: PCT/JP2018/027407
Authority: WO
Inventors: 持丸　昌己; 五十嵐　美照
Original assignee: オイレス工業株式会社
Priority date: 2017-07-31
Filing date: 2018-07-20
Publication date: 2019-02-07
Also published as: JP2019027958A

Abstract

Provided are: a load cell capable of accurately measuring a load in a thrust direction; and a bearing using the load cell. This load cell (1) is provided with: a deformable body (2); strain gauge sets (3a-3d) for detecting strain occurring in the deformable body (2). The deformable body (2) has: two annular flat plates (20a, 20b) arranged in the direction of an axis O; and a connection member (21) connecting the annular flat plates (20a, 20b). The connection member (21) comprises a plurality of arms (22) arranged on a circle centered on the axis O, the plurality of arms (22) being positioned at equal intervals and being line-symmetric with respect to the axis O, and the connection member (21) is tilted relative to the axis O. The strain gauge sets (3a-3d) each comprise four strain gauges (30a-30d) constituting a Wheatstone bridge circuit, and are attached to locations line-symmetric with respect to the axis O of the connection member (21).

Description

Load cell and bearing

The present invention relates to a load cell, and more particularly to a load cell suitable for measuring the load of a vehicle applied to a suspension.

Patent Document 1 discloses a bearing capable of measuring a load applied to a suspension while supporting the load of a vehicle. The bearing is connected to a rotating body, a top race and a bottom race relatively rotatably combined via the rotating body, a top cup connected to the top race and disposed on the vehicle body side, and a bottom race And a deformation sensor such as a strain gauge attached to the top race or the top cup. In this bearing, the top race or the top cup functions as a straining body, the strain of the straining body is detected by a deformation sensor, and the load in the thrust direction (the load of the vehicle) is calculated based on the magnitude of the detected strain. ing.

JP 2004-177411 A

However, since the bearing described in Patent Document 1 is configured to support the load of the vehicle applied to the suspension, it is designed to have sufficient rigidity with respect to the load in the thrust direction. Therefore, when the top race or the top cup is used as a strain generating body, the strain of the strain generating body against the load in the thrust direction is small, so the detection sensitivity of the deformation sensor becomes low, and the load of the vehicle can be measured accurately. difficult.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a load cell capable of accurately measuring a load in a thrust direction and a bearing using the load cell.

In order to solve the above problems, in the present invention, two annular flat plates are arranged in the axial direction, and the annular flat plates are connected by a connecting member to constitute a strain generating body, and the connecting member is axially The strain gauge was attached to the connecting member while being inclined with respect to the heart.

For example, the load cell of the present invention
Strain generating body,
A strain gauge for detecting strain generated in the strain generating body;
The strain body is
Two annular flat plates arranged in the axial direction,
And a connecting member for connecting between the two annular flat plates,
The connecting member is inclined with respect to the axial center,
The strain gauge is attached to the connecting member.

Also, the bearing of the present invention is
A bearing that supports the load of a vehicle applied to a suspension,
An upper case attached to the vehicle body side,
A lower case attached to a spring side constituting the suspension and rotatably combined with the upper case;
The above-mentioned load cell disposed between the upper case and the vehicle body.

In the load cell of the present invention, since the connecting member constituting the strain generating body is inclined with respect to the axial center, the connecting member is compressed and deformed against the load in the thrust direction applied in the direction of contracting between the two annular flat plates. In addition to this, bending deformation also occurs, and distortion is greater than in the case of only compression deformation. This increases the detection sensitivity of the strain gauge. Therefore, according to the present invention, the load in the thrust direction can be measured accurately.

FIG. 1A and FIG. 1B are a front view and a side view of a load cell 1 according to an embodiment of the present invention. FIGS. 2A and 2B are a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB of the load cell 1 shown in FIG. 1A. 3 (A) and 3 (B) are a cross-sectional view and a cross-sectional view of the load cell 1 shown in FIG. 1 (B), respectively. FIG. 4A is a diagram for explaining the strain of the strain generating body 2 with respect to the load in the thrust direction, and FIG. 4B is a diagram for explaining the strain of the strain generating body 2 with respect to the load in the radial direction. FIG. FIG. 5 is a partial cross-sectional view of the damper assembly 5, the bearing 6, and the upper support 7 that constitute the vehicle suspension 4. 6 (A), 6 (B) and 6 (C) are a front view, a rear view and a side view of the sliding bearing 6, and FIG. 6 (D) is a sliding bearing shown in FIG. 6 (A). 6 is a cross-sectional view taken along line E-E of FIG.

Hereinafter, an embodiment of the present invention will be described.

FIG. 1A and FIG. 1B are a front view and a side view of a load cell 1 according to the present embodiment. 2 (A) and 2 (B) are a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB of the load cell 1 shown in FIG. 1 (A). 3 (A) and 3 (B) are a cross-sectional view taken along the line CC and a cross-sectional view taken along the line DD of the load cell 1 shown in FIG. 1 (B).

The load cell 1 according to the present embodiment is for measuring the load applied in the thrust direction (axial center O direction), and a plurality of strains for detecting strain generated in the strain generating body 2 and the strain generating body 2 Gauge sets 3a to 3d (hereinafter, also simply referred to as strain gauge set 3).

The strain generating body 2 is formed of a thermoplastic resin such as polyacetal resin or polyamide resin, and is a connecting member for connecting between two annular

flat plates

20a and 20b arranged in the axial center O direction and the two annular

flat plates

20a and 20b. And 21.

The annular

flat plates

20a and 20b are disposed parallel to each other with their centers aligned with the axis O.

The connecting member 21 has a plurality of arm portions 22 arranged at equal intervals on the circumference centering on the axial center O and in line symmetry with respect to the axial center O. The arm portion 22 is inclined in a direction away from the axial center O as the sectional shape in the plane including the axial center O goes from the annular flat plate 20 a to the annular flat plate 20 b. Therefore, the two arm portions 22 arranged in line symmetry with respect to the axis O have a cross-sectional shape in a plane including the axis O inclined in line symmetry with respect to the axis O to form a V shape. There is no. As a result, in the strain-generating body 2, the cross-sectional shape in the plane including the axial center O becomes a Z shape that is line symmetrical with respect to the axial center O (see FIGS. 2A and 2B).

The strain gauge set 3 is arranged to be line symmetrical with respect to the axis O. Specifically, the

strain gauge sets

3a and 3b are arranged to be axisymmetric with respect to the axis O, and the

strain gauge sets

3c and 3d are arranged to be axisymmetrical with respect to the axis O.

Further, the strain gauge set 3 is constituted by four strain gauges 30a to 30d constituting a Wheatstone bridge circuit. Here, the strain gauge 30a is attached to the outer wall surface (surface on the radially outer side) 221 of the end 220a of the arm 22 on the side of the annular flat plate 20a, and the strain gauge 30b is on the side of the annular flat 20b of the arm 22. Is attached to the outer wall surface 221 of the end 220 b of the The strain gauge 30c is attached to the inner wall surface (surface on the radially inward side) 222 of the end 220a of the arm 22 on the side of the annular flat plate 20a, and the strain gauge 30d is on the side of the annular flat 20b of the arm 22. It is attached to the inner wall surface 222 of the end 220 b.

Next, distortion of the strain generating body 2 when a load is applied to the load cell 1 having the above-described configuration will be described.

FIG. 4A is a diagram for explaining the strain of the strain generating body 2 with respect to the load in the thrust direction, and FIG. 4B is a diagram for explaining the strain of the strain generating body 2 with respect to the load in the radial direction. FIG. FIG. 4A and FIG. 4B correspond to a diagram in which a part of FIG. 2B is omitted.

In the load cell 1 configured as described above, the plurality of arm portions 22 constituting the connecting member 21 of the strain generating body 2 are at equal intervals on the circumference centered on the axis O and are line symmetrical with respect to the axis O It is arranged as. Further, the cross-sectional shape in the plane including the axis O is inclined in the direction away from the axis O as it goes from the annular flat plate 20 a to the annular flat plate 20 b. Therefore, as shown in FIG. 4A, when a thrust load T, which is a load in the axial center O direction that shrinks between the two annular

flat plates

20a and 20b constituting the strain generating body 2, is applied to the load cell 1, each arm In the portion 22, in addition to the compressive deformation in the direction of the axis O, the end 220a on the side of the annular flat plate 20a is bent radially inward, and the end 220b on the side of the annular flat 20b is bent so as to radially outward. Do. By this bending deformation, each arm portion 22 is distorted in the direction in which the outer wall surface 221 extends, and is distorted in the direction in which the inner wall surface 222 contracts. For this reason, distortion of the strain generating body 3 becomes larger than that in the case of only compression deformation, and the detection sensitivity of distortion which can be detected by the strain gauge set 3 becomes high.

Further, as shown in FIG. 4B, when a radial load R, which is a load in a direction perpendicular to the direction of the axis O, is applied to the load cell 1, the arm 22 on the side to which the radial load R is applied (FIG. In (B), in the left arm portion 22), the outer wall surface 221 is distorted in the extending direction, while the inner wall surface 222 is distorted in the contracting direction. On the other hand, in the arm portion 22 on the side to which the radial load R is applied and the arm portion 22 located in line symmetry with the axial center O direction (the arm 22 on the right in FIG. While 221 is distorted in the shrinking direction, the inner wall surface 222 is distorted in the extending direction. That is, since the two arm portions 22 located in line symmetry with respect to the axis O direction are distorted in opposite directions with respect to the radial load R, they are located in line symmetry with respect to the axis O direction. The polarity of the detection value of the strain gauge set 3 attached to the two arms 22 is reversed. In the present embodiment, strain gauge set 3 is arranged so as to be line symmetrical with respect to axis O. Therefore, the influence of radial load R is canceled by averaging the detection values of each strain gauge set 3. can do.

Therefore, according to the load cell 1 according to the present embodiment, the strain detection sensitivity that can be detected by the strain gauge set 3 can be increased, and furthermore, by averaging the detection values of the strain gauge set 3 Since the influence of the radial load R included in the detection value can be offset, the thrust load T can be accurately measured by calculating the thrust load T based on the average value of the detection values of the strain gauge set 3 . Further, by changing the inclination of the plurality of arm portions 22 constituting the connecting member 21 with respect to the axial center O, it is possible to adjust the detection sensitivity of distortion which can be detected by the strain gauge set 3.

Below, the bearing using the load cell 1 which concerns on this Embodiment is demonstrated.

FIG. 5 is a partial cross-sectional view of the damper assembly 5, the slide bearing 6, and the upper support 7 that constitute the vehicle suspension 4. As shown in FIG.

The vehicle suspension 4 is used for suspension of a vehicle such as a car, and as shown, a damper assembly 5 including a shock absorber 50, an upper support 7 for mounting the damper assembly 5 on the vehicle body side, and a damper assembly And a sliding bearing 6 disposed between the upper support 7 and the upper support 7.

The damper assembly 5 includes a coil spring 51, a lower spring seat 52, a bump stopper 53, and a dust boot 54, in addition to the shock absorber 50.

The coil spring 51 is coaxially disposed with the shock absorber 50 so as to surround the shock absorber 50, and its upper end 510 is supported by an upper spring seat 55 provided on the slide bearing 6, and its lower end 511 is It is supported by a lower spring seat 52 provided on the shock absorber 50.

The bump stopper 53 is mounted on the piston rod 56 of the shock absorber 50 and prevents the shock absorber 50 from colliding with the body of the vehicle when the piston rod 56 is compressed.

The dust boot 54 is mounted so as to cover the piston rod 56 on which the bump stopper 53 is mounted, and prevents dust, muddy water and the like from adhering to the piston rod 56.

The slide bearing 6 is disposed between the damper assembly 5 and the upper support 7 and supports the load applied to the damper assembly 5 while allowing relative rotation between the coil spring 51 and the upper support 7.

Moreover, the slide bearing 6 is equipped with the load cell 1 which concerns on this Embodiment. The load cell 1 outputs signals from the plurality of strain gauge sets 3 according to the strain generated in the strain generating body 2 by the load supported by the slide bearing 6. The signals output from the plurality of strain gauge sets 3 are input to the load measuring unit 8 mounted on the vehicle. The load measuring unit 8 calculates an average value of detection values indicated by the signals output from the plurality of strain gauge sets 3 and measures a load applied to the damper assembly 5 based on the average value. Then, the vehicle weight is calculated based on the detected load.

For example, when the slide bearing 6 provided with the load cell 1 is mounted on the suspension of all four wheels of the vehicle, the vehicle weight is calculated by summing the loads measured by the load cells 1. Further, for example, when the slide bearing 6 including the load cell 1 is mounted only on the suspension of the front wheel or the rear wheel, the vehicle weight is calculated by doubling the total of the loads detected by the load cells 1. Further, for example, in the case where the slide bearing 6 including the load cell 1 is mounted on only one suspension of four wheels, the vehicle weight is calculated by quadrupling the load detected by the load cell 1.

6 (A), 6 (B) and 6 (C) are a front view, a rear view and a side view of the sliding bearing 6, and FIG. 6 (D) is a sliding bearing shown in FIG. 6 (A). 6 is a cross-sectional view taken along line E-E of FIG.

The slide bearing 6 has a receiving hole 60 for receiving the piston rod 56 on which the bump stopper 53 is mounted. The slide bearing 6 is rotatably combined with the upper case 61 and the upper case 61, and is disposed in the lower case 62 forming an annular space 64 between the upper case 61 and the lower case 62. An annular center plate 63 and a load cell 1 disposed between the upper case 61 and the upper support 7 are provided.

Upper case 61 is formed of thermoplastic resin having excellent sliding characteristics such as polyacetal resin impregnated with lubricating oil as needed, and is inserted to upper support 7 through load cell 1 with piston rod 56 inserted. It is attached.

Lower case 62 is formed of thermoplastic resin such as polyamide resin reinforced with glass fiber etc. if necessary, and upper end portion 510 of coil spring 51 in a state where piston rod 56 mounted with bump stopper 53 is inserted. It also functions as an upper spring seat 55 that supports the

The center plate 63 is an annular member formed of a material excellent in sliding characteristics, such as PTFE (polytetrafluoroethylene), a thermoplastic resin to which PTFE is added, a brass alloy, etc. By sliding with the upper case 61 in a state in which relative rotation with the case 62 is restrained, it functions as a bearing body that realizes free rotation between the upper case 61 and the lower case 62.

Heretofore, an embodiment of the present invention has been described.

The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention.

For example, in the above embodiment, the case where four strain gauge sets 3a to 3d are used as the plurality of strain gauge sets 3 for detecting distortion generated in the strain generating body 2 is described as an example. However, the present invention is not limited to this. A plurality of strain gauge sets 3 may be arranged in line symmetry with respect to the axis O.

Further, in the above embodiment, the strain gauge set 3 is constituted by the four strain gauges 30a to 30d constituting the Wheatstone bridge circuit, and the strain gauges 30a to 30d are formed by the outer wall surfaces of both

end portions

220a and 220b of the arm portion 22. And 221 attached to the inner wall surface 222. However, the present invention is not limited to this. The strain gauge set 3 may be configured to include at least one strain gauge, and the mounting position thereof may be any connecting member 21 that bends in addition to compressive deformation with respect to the thrust load T. You may attach it.

Further, in the above embodiment, the connecting members 21 for connecting the annular

flat plates

20a and 20b are arranged at equal intervals on the circumference centering on the axial center O and in line symmetry to the axial center O. It is comprised by the several arm part 22 arrange | positioned. However, the present invention is not limited to this. The connecting member may have a cross-sectional shape in a plane including the axial center O inclined in line symmetry with respect to the axial center O. For example, the connecting member may be a tubular member whose diameter increases from one of the annular

flat plates

20a and 20b to the other.

Further, in the above embodiment, the annular

flat plates

20a and 20b have the same diameter, but the present invention is not limited to this. For example, as shown in FIG. 5, when the load cell 1 is incorporated into the slide bearing 6 and mounted on the vehicle suspension 4, the annular flat plate 20a is adjusted to the size of the upper support 7 to which the annular flat plate 20a is attached, and the annular flat plate 20b is annular By matching the size of the upper case 61 of the slide bearing 6 to which the flat plate 20b is attached, the sizes of the annular

flat plates

20a and 20b may be made different from each other.

In addition, as a bearing using the load cell 1 according to the above embodiment, the slide bearing 6 is described as an example. However, the bearing combined with the load cell 1 is not limited to the sliding bearing. For example, it may be a rolling bearing. Moreover, the load cell of the present invention can be used not only for bearings but also for various applications for measuring thrust loads.

1: load cell, 2: strain generating body, 3, 3a to 3d: strain gauge set, 4: suspension for vehicle, 5: damper assembly, 6: sliding bearing, 7: upper support, 8: load measuring unit, 20a, 20b : Ring plate, 21: Link member, 22: Arm, 30a-30d: Strain gauge, 50: Shock absorber, 51: Coil spring, 52: Lower spring seat, 53: Bump stopper, 54: Dust boot, 55: Upper Spring seat 56:

Piston rod

220a, 220b: end of arm 22 221: outer wall of arm 22 222: inner wall of arm 22 510: upper end of coil spring 51 511: coil spring Lower end of 51

Claims

Strain generating body,
A strain gauge for detecting strain generated in the strain generating body;
The strain body is
Two annular flat plates arranged in the axial direction,
And a connecting member for connecting between the two annular flat plates,
The connecting member is inclined with respect to the axial center,
The load cell, wherein the strain gauge is attached to the connecting member.
The load cell according to claim 1, wherein
The connecting member is
A cross-sectional shape in a plane including the axis is axisymmetrically inclined with respect to the axis;
The strain gauge
A load cell, wherein the load cells are attached at positions axisymmetrically with respect to the axial center of the connection member.
The load cell according to claim 2, wherein
The connecting member is
A load cell comprising a plurality of arm portions arranged at equal intervals on a circumference centered on the axis and at line symmetry with respect to the axis.
The load cell according to any one of claims 1 to 3, wherein
The strain gauge
A load cell characterized by being attached respectively to an inner wall surface of the connection member located on the inner edge side of the annular flat plate and an outer wall surface of the connection member located on the outer edge side of the annular flat plate.
The load cell according to any one of claims 1 to 4, wherein
The strain gauge
A load cell, which is attached to each end of the connecting member in the axial direction.
A bearing that supports the load of a vehicle applied to a suspension,
An upper case attached to the vehicle body side,
A lower case attached to a spring side constituting the suspension and rotatably combined with the upper case;
The load cell according to any one of claims 1 to 5, which is disposed between the upper case and the vehicle body.