JP7204091B2 - torque transducer - Google Patents

Description

The present invention relates to a torque transducer that measures torque and converts it into an electrical signal.

Conventionally, as a measuring device for measuring the torque generated in the wheels of an automobile rotating at high speed, there is a torque transducer having a structure in which connecting flanges are provided at both ends and a cylindrical strain-generating portion is connected between the flanges. It is publicly known. This torque transducer has a strain-sensitive resistor attached to a cylindrical strain-generating portion, and electrically converts the amount of strain of the strain-generating portion proportional to the torque transmitted from the drive-side flange to the driven-side flange. are doing. In addition to high-speed rotation, it is also required to measure abrupt torque changes, so the strain-generating part is required to have high rigidity and at the same time to ensure high responsiveness.

JP-A-6-229853 JP-A-2001-330525

For this purpose, a method of providing a thin flat surface on a portion of the cylindrical surface of the outer periphery of the strain-generating portion and attaching a strain-sensitive resistor to this flat surface is disclosed in Japanese Unexamined Patent Application Publication No. 2002-100000. In this configuration, since the strain-sensitive resistor is attached to the outer periphery, it is necessary to protect the strain-sensitive resistor and the wiring drawn therefrom from the influence of centrifugal force when rotating at high speed. Furthermore, since the thickness of the thin portion is not constant in the circumferential direction but varies, it is necessary to position the strain-sensitive resistor with high accuracy in the circumferential direction, and there is room for improvement. .

On the other hand, Japanese Patent Application Laid-Open No. 2002-200000 discloses a method of increasing the rigidity by forming the entire circumference of the strain-generating portion in an arc shape. However, there is room for improvement in determining the optimum minimum wall thickness and arc dimensions for increasing the rigidity of the strain-generating portion and increasing the sensitivity to strain.

In view of such problems, an object of the present invention is to provide a highly rigid and highly accurate torque transducer.

In order to achieve the above object, the torque transducer of the present invention has
a hollow cylindrical strain-generating portion;
flange portions provided at both ends of the strain-generating portion;
A torque converter that converts the torque acting on the strain-generating part into an electric quantity,
The strain-generating portion has a plurality of groove-shaped thin-walled portions,
Each thin-walled portion is placed on the outer peripheral surface of the strain-generating portion at equal depths from the center axis of the strain-generating portion, at the same position in the direction of the center axis, and at equal intervals and equal length along the circumferential direction. provided respectively,
A strain-sensitive resistor is attached to the inner peripheral surface of each thin-walled portion of the strain-generating portion ,
In the cross-sectional shape obtained by cutting each thin-walled portion on a plane that includes the central axis, the line segment on the outer peripheral side includes a substantially circular arc, and the thickness of each thin-walled portion at the start and end points in the circumferential direction gradually changes. there is

Also, it has a circuit board and an antenna,
The circuit board is arranged in the hollow portion of the strain-generating portion and connected to the strain-sensitive resistor,
The antenna is arranged on the flange portion of an annular wiring board on which conductor wires are printed, and wirelessly transmits the torque signal output from the circuit board .

According to the present invention, the strain-flexing portion having the discontinuous thin-walled portion increases the thickness of the strain-flexing portion to increase the rigidity, and the thin-walled portion is provided with a plurality of thin portions having equal thicknesses and lengths. It is possible to provide a torque transducer in which the positional accuracy of the strain-sensitive resistor attached to is relaxed.

1 is a perspective external view of a torque converter according to a first embodiment of the present invention; FIG. It is the side view (a) and perspective view (b) of the measurement part of the torque transducer which concerns on the 1st Embodiment of this invention. FIG. 4 is a cross-sectional view of a measuring section of the torque transducer according to the first embodiment of the present invention; It is an AA cross-sectional view of the measuring portion of the torque transducer according to the first embodiment of the present invention. It is the side view (a) and perspective view (b) of the measurement part of the torque transducer which concerns on the 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view of a measuring section of a torque transducer according to a second embodiment of the invention; It is BB sectional drawing of the measurement part of the torque transducer which concerns on the 2nd Embodiment of this invention. FIG. 4 is a diagram showing a Wheatstone bridge circuit including strain-sensitive resistors of the torque transducers according to the first and second embodiments of the present invention;

DETAILED DESCRIPTION OF THE INVENTION Torque transducers according to embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective external view of a torque converter 1 according to a first embodiment of the invention.

The torque converter 1 includes a torque measuring section 13 and an electrical component box 9 . The torque measuring section 13 includes the strain-generating section 2, flange sections 3a-3b, strain-sensitive resistors G1-G8 therein, and a circuit board 12. FIG. A power supply unit 7 and a rotation speed detection unit 8 are provided on the top surface of the electrical component box 9 . The torque measuring section 13 and the electric component box 9 are separately configured, and the torque transducer 1 is used by installing both at predetermined positions and intervals, and the torque acting on the strain generating section 2 is measured as an electric quantity. Convert to

The flange portion 3a is made of a highly rigid annular metal that is not easily deformed. The flange portion 3a has a plurality of screw holes arranged at equal angular intervals, and is connected to a drive member on the drive side by bolts.

The flange portion 3b is also made of a highly rigid annular metal that is not easily deformed. The flange portion 3b has a plurality of screw holes arranged at equal angular intervals, and is connected to the load member on the dependent side by bolts.

The gear 4 is a spur gear provided on the side of the flange portion 3a. The gear 4 has a shape projecting radially from the outer periphery of the flange portion 3a, and is disposed between the flange portions 3a and 3b in the rotation axis direction.

The strain generating portion 2 is located between the flange portion 3a and the flange portion 3b in the rotation axis direction, and is concentric with the flange portion 3a and the flange portion 3b. The strain-generating portion 2 has a hollow columnar shape, and flange portions 3a and 3b at both ends of the strain-generating portion 2 are formed of an integral member. The diameter of the outer cylindrical surface of the strain-generating portion 2 is smaller than the outer diameters of the flange portions 3a and 3b, and the thickness thereof is also relatively small.

The rotation speed detection unit 8 uses the gear 4 to detect the rotation speed and rotation direction of the torque measurement unit 13 . The rotational speed detection unit 8 has two magnetoresistive elements arranged at a predetermined distance from the gear 4 on the circumference of the rotating gear 4 close to the addendum circle of the gear. A change in magnetic force due to the tip of the tooth of the gear 4 passing through is detected to detect the rotation speed and rotation direction.

The antenna 14 is for wirelessly transmitting a signal of the torque value measured by the torque measuring section 13 . The antenna 14 is, for example, an annular printed wiring board on which conductor wires are printed. A lead wire from the antenna 14 is led into the torque measuring section 13 through a hole provided in the outer cylindrical surface of the flange section 3a and connected to the circuit board 12 fixed inside the torque measuring section 13. there is

The power receiving side coil 5 is a coil wound around the outer periphery of the flange portion 3 b and is for receiving power from the power feeding portion 7 . A lead wire from the power receiving side coil 5 is led into the torque measuring section 13 through a hole provided in the cylindrical surface of the flange section 3b, and connected to the circuit board 12 fixed inside the torque measuring section 13. there is

In order to transmit electric power to the torque measuring unit 13 in a contactless manner, the power supply unit 7 accommodates a power transmission side coil that is coupled with the power reception side coil 5 at a predetermined interval to form a rotary transformer.

The lid 6 is provided to protect the members arranged inside the torque measuring section 13 from wind and dust generated by high-speed rotation.

The electrical component box 9 accommodates a substrate including a circuit for contactlessly transmitting electric power to the torque measurement unit 13 via the power supply unit 7 . Further, a circuit for receiving a digital torque signal from the antenna 14 of the torque measuring section 13 and demodulating it to output a torque value, and a rotational speed detecting section 8 for detecting the rotational speed and rotational direction of the torque measuring section 13. A board containing a circuit for output and a power supply circuit that converts power supplied from the outside and supplies power for each circuit is accommodated.

2A and 2B are a side view (a) and a perspective view (b) showing a part of the measuring section of the torque transducer according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the side view (a) of FIG. 2 cut along a vertical plane including the central axis of the measuring section. FIG. 4 is a cross-sectional view along AA in FIG.

The outer peripheral surface 2a of the strain-generating portion 2 is provided with, for example, groove-like elliptical thin-walled portions 10a to 10d. The thin portions 10a to 10d have an oval groove shape, and the longitudinal sides thereof extend along the circumferential direction. The four thin portions 10a to 10d are arranged at equal intervals of 90 degrees along the circumferential direction around the central axis of the strain-generating portion 2. As shown in FIG. The four thin portions 10a to 10d have the same length L1 in the circumferential direction, the same width W in the direction of the central axis, and are arranged at the same position in the direction of the central axis. The surfaces extending in the circumferential direction of the four thin portions 10a to 10d, that is, the bottom surfaces of the thin portions 10a to 10d are cylindrical surfaces. The strain generating portion 2 around the thin portions 10a to 10d is a cylindrical surface having a radius R0, and the bottom portions of the thin portions 10a to 10d are cylindrical surfaces having a radius R1. That is, the bottoms of the groove-shaped thin portions 10a to 10d are equidistant from the central axis of the strain-generating portion 2. As shown in FIG. These four thin portions 10a to 10d have shapes that can be machined by, for example, a flat end mill.

Strain sensitive resistors G1 to G8 are attached to the inner peripheral surfaces 2b of the thin portions 10a to 10d. A strain sensitive resistor G1 and a strain sensitive resistor G2 are attached corresponding to the thin portion 10a, a strain sensitive resistor G3 and a strain sensitive resistor G4 are attached corresponding to the thin portion 10b, and a strain sensitive resistor G4 are attached corresponding to the thin portion 10c. A strain-sensitive resistor G5 and a strain-sensitive resistor G6 are attached to the thin portion 10d, and a strain-sensitive resistor G7 and a strain-sensitive resistor G8 are attached to the thin portion 10d. The strain sensitive resistors G1 to G8 are shear type strain gauges, for example. When each of the strain sensitive resistors G1 to G8 is viewed in the radial direction from the axial center, the strain sensitive resistor G1 is attached so as to have the maximum sensitivity at an angle of -45 degrees with respect to the axial direction. G2 is affixed with maximum sensitivity to axial and +45 degree angles. The strain-sensitive resistors G3-G8 are similarly attached to the inner peripheral surfaces 2b of the thin portions 10b-10d. By forming the adjacent strain-sensitive resistor G1 and strain-sensitive resistor G2 on, for example, one substrate, errors in attachment angle can be reduced. Of course, the strain-sensitive resistor G3 and the strain-sensitive resistor G4, the strain-sensitive resistor G5 and the strain-sensitive resistor G6, and the strain-sensitive resistor G7 and the strain-sensitive resistor G8 are similarly formed on one substrate. A similar effect can be obtained by using

A circuit board 12 is arranged and fixed in the hollow portion of the strain generating portion 2 . Wiring drawn from the strain sensitive resistors G1 to G8 is connected to the circuit board 12 . The circuit board 12 has a Wheatstone bridge circuit including strain sensitive resistors G1 to G8 (FIG. 8). The circuit board 12 includes an amplifier circuit, an analog/digital conversion circuit, an arithmetic circuit, a modulation circuit, and a transmission circuit. The amplifier circuit amplifies the analog signal output from the Wheatstone bridge circuit including the strain sensitive resistors G1 to G8. An analog/digital conversion circuit converts this analog signal into a digital signal. A computation circuit computes this digital signal to generate a torque signal representing a torque value. A modulation circuit modulates the digital torque signal to produce a modulated signal. The transmission circuit puts the modulated signal on a carrier wave and transmits it to the reception circuit in the electrical component box 9 . In addition, the circuit board 12 is connected to an electric wire drawn out from the power receiving side coil 5, receives the transmitted power, and uses a rectifier circuit that rectifies the power to form an amplifier circuit, an analog/digital conversion circuit, an arithmetic circuit, and a modulation circuit. It powers the circuit, the transmit circuit and the Wheatstone bridge circuit.

5A and 5B are a side view (a) and a perspective view (b) showing part of a measuring section of a torque transducer according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view of the side view (a) of FIG. 5 cut along a vertical plane including the central axis of the measuring section. 7 is a cross-sectional view taken along line BB in FIG. 6. FIG. The torque transducer according to the second embodiment differs from the torque transducer according to the first embodiment in the shape of the thin portion. Therefore, only the differences from the first embodiment will be described below.

The thin-walled portions 11a to 11d of the torque transducer according to the second embodiment have an oval groove shape, and the longitudinal sides thereof extend along the circumferential direction. The bottom surfaces of the thin portions 11a to 11d are curved surfaces formed by rotating circular arcs around their axes. The four thin portions 11a to 11d are arranged around the central axis of the strain-generating portion 2 along the circumferential direction at equal intervals of 90 degrees. The four thin portions 11a to 11d have the same length L2 in the circumferential direction, the same width W in the axial direction, and are arranged at the same position in the direction of the central axis. In the cross-sectional shape obtained by cutting the four thin-walled portions 11a to 11d on a plane including the central axis of the strain-generating portion 2, the outer peripheral side is a line segment of a substantially circular arc. The strain generating portion 2 around the thin portions 11a to 11d is a cylindrical surface with a radius R0, and the deepest bottoms of the thin portions 11a to 11d are on the ridgelines with a radius R2. That is, the deepest bottoms of the groove-shaped thin-walled portions 11a to 11d are equidistant from the center axis of the strain-generating portion 2. As shown in FIG. Therefore, the four thin portions 11a to 11d have shapes that can be machined by, for example, a ball end mill.

FIG. 8 is a diagram showing a Wheatstone bridge circuit including the strain-sensitive resistors of the torque transducers according to the first and second embodiments of the present invention.

4 and 7, the strain-sensitive resistor G1 and the strain-sensitive resistor G5 are actually arranged to face each other at an angle of 180 degrees across the axis of the strain-generating portion 2. In the Wheatstone bridge circuit, the side S1 are arranged in series. On the other hand, the strain-sensitive resistor G3 and the strain-sensitive resistor G7 are actually arranged facing each other at an angle of 180 degrees across the axis of the strain-generating portion 2, and are arranged in series with the side S3 in the Wheatstone bridge circuit. be. In the Wheatstone bridge circuit, a side S1 where the strain-sensitive resistor G1 and the strain-sensitive resistor G5 are arranged in series and a side S3 where the strain-sensitive resistor G3 and the strain-sensitive resistor G7 are arranged in series form a bridge. Configured as opposite sides of the circuit.

Similarly, the strain-sensitive resistor G2 and the strain-sensitive resistor G6 are substantially arranged facing each other at an angle of 180 degrees across the axis of the strain-generating portion 2, and arranged in series with the side S2 in the Wheatstone bridge circuit. be done. On the other hand, the strain-sensitive resistor G4 and the strain-sensitive resistor G8 are actually arranged facing each other at an angle of 180 degrees across the axis of the strain-generating portion 2, and are arranged in series on the side S4 in the Wheatstone bridge circuit. be. In the Wheatstone bridge circuit, a side S2 where the strain-sensitive resistor G2 and the strain-sensitive resistor G6 are arranged in series and a side S4 where the strain-sensitive resistor G4 and the strain-sensitive resistor G8 are arranged in series form a bridge. Configured as opposite sides of the circuit.

In both the torque transducers according to the first embodiment and the second embodiment of the present invention, a discontinuous thin portion is provided on the outer circumference of the strain-generating portion. can increase stiffness. Further, by providing a plurality of thin portions having the same thickness and length, it is possible to realize a highly accurate torque transducer even if the circumferential positional accuracy of the strain-sensitive resistor attached to the thin portions is relaxed. By appropriately adjusting the depth of the thin portion, it is also possible to change the torque measurement range.

Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

As an application example of the present invention, it is possible to apply it to a device for measuring torque generated in a wheel of an automobile rotating at high speed.

Reference Signs List 1: Torque transducer 2: Strain-generating portion 2a: Outer peripheral surface 2b: Inner peripheral surfaces 3a, 3b: Flange portion 4: Gear 5: Power receiving side coil 6: Lid 7: Power supply unit 8: Rotational speed detector 9: Electrical equipment Boxes 10a to 10d: thin portions 11a to 11d: thin portion 12: circuit board 13: torque measuring portion 14: antennas G1 to G8: strain sensitive resistors

Claims (2)

a hollow cylindrical strain-generating portion;
flange portions provided at both ends of the strain-generating portion;
A torque converter that converts the torque acting on the strain-generating portion into an electric quantity,
The strain-generating portion has a plurality of groove-shaped thin portions,
The thin portions are formed on the outer peripheral surface of the strain-flexing portion at equal depths from the central axis of the strain-flexing portion, at the same position in the direction of the central axis, and at equal intervals along the circumference. and are provided with equal lengths, respectively,
A strain-sensitive resistor is attached to the inner peripheral surface of each thin-walled portion of the strain-generating portion ,
In the shape of the cross-sectional portion obtained by cutting each thin-walled portion with a plane containing the central axis, a line segment on the outer peripheral side includes a substantially circular arc,
A torque transducer in which the thickness of each of the thin portions in the circumferential direction gradually changes at the starting point and the end point. further comprising a circuit board and an antenna;
The circuit board is arranged in a hollow portion of the strain-generating portion and connected to the strain-sensitive resistor,
2. The torque transducer according to claim 1, wherein said antenna is arranged on said flange portion by means of an annular wiring board on which conductor wires are printed, and wirelessly transmits a torque signal output from said circuit board.

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