JP2002039881A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor capable of measuring torques even at high temperatures or in an environment where water or oil exists, while being structurally simple, inexpensive and highly reliable. SOLUTION: The torque sensor includes a shaft 1 with a magnetized part magnetized to produce a magnetic field matching the strength of torque applied, and a magnetic field detection means placed near the shaft 1 for detecting the strength of the magnetic field generated by the torque applied to the shaft 1, with the shaft 1 being separated from the magnetic field detection means, and the detection means being detachably mountable to a housing 30 or the like containing the shaft 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detector for detecting torque applied to a shaft in a non-contact manner.

[0002]

2. Description of the Related Art Conventional torque detectors of this type include, for example, Japanese Patent Publication No. Hei 7-117664 and Japanese Patent No. 28119.
No. 80, a groove provided directly with ± 45 ° on a magnetostrictive alloy shaft or ±
A torque detection shaft provided with a detection unit bonded to a shaft with an amorphous alloy foil subjected to a 45 ° list processing is supported by a bearing in a rotatable and axially restricted position, and a detection unit is provided on the outer periphery of the torque detection shaft. And a detection coil disposed integrally with a predetermined gap therebetween. Then, when a torque is applied to the torque detection shaft, a change in magnetic permeability due to a change in stress of the magnetostrictive alloy shaft or the amorphous alloy foil is detected as a change in impedance of the detection coil (prior art 1).

[0003] Also, Japanese Patent No. 2797021 discloses that
There is described a torque measuring device that detects a phase displacement of a magnetic coupling body as a change in impedance by a torsion bar in which a shaft to which torque is applied is formed to be thin and easy to twist in advance by a detection coil disposed on an outer periphery (prior art). 2). Further, there is a strain detection type in which a strain gauge is directly adhered and fixed to a shaft to which a torque is applied, and a distortion amount due to the torque is taken out to the outside by a slip ring (prior art 3).

[0004]

SUMMARY OF THE INVENTION In the prior art 1,
When machining a groove of ± 45 ° directly on the magnetostrictive alloy shaft, there are many parameters that affect the torque characteristics, and not only the number of parts is large, but also the accuracy of each part is required, so manufacturing is troublesome and expensive. Problem. In addition, in the case of using an amorphous alloy foil, it is troublesome to bond the amorphous alloy foil to the torque detection shaft, and the temperature characteristics are poor due to a difference in the thermal expansion coefficient between the bonded amorphous alloy foil and the torque detection shaft. There's a problem.

[0005] Further, the torque measuring device of the prior art 2 is:
Since the shaft diameter of the torsion bar is made thinner to make it easier to twist, the mechanical strength is insufficient, and the mechanical stopper etc. to compensate for this is built in the measuring device, so the outer dimensions become large, In addition, it is expensive because of the large number of parts. Further, the distortion detection method of the prior art 3 uses a slip ring as a means for extracting the amount of distortion as a signal to the outside. Therefore, it is necessary not only to periodically replace the slip ring but also to incorporate the slip ring. Therefore, the external dimensions are large, and expensive products require maintenance costs, so that the range of use for specific devices such as inspection equipment is limited.

Further, in the torque detectors of the prior arts 1 to 3, since the torque detection shaft and the detection coil and the electric parts are integrally incorporated in the container due to the structure, the torque detector is used in an environment where there is much water or oil. Can not be used, and it is possible to use it to some extent by taking waterproof and oil-proof measures, but it is unavoidable that the cost increases. In addition, when used in a high-temperature environment, since all parts have the same temperature, there is also a problem that the specification of electrical parts and resin parts is restricted, and the operating temperature range is limited.

[0007] Further, in a device incorporating a torque detector,
Use space is limited due to the need for a large space for assembling the container.Waterproof means is required for the lead wire outlet to take out the electrical output from the device. Wiring process was troublesome.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can surely measure a torque even in a high temperature environment or in an environment where water or oil exists, and has a simple and compact structure. It is an object of the present invention to provide an inexpensive and highly reliable torque detector that can perform the torque detection.

[0009]

According to the present invention, there is provided a torque detector comprising: a shaft having a magnetized portion magnetized so as to generate a magnetic field corresponding to the intensity of an applied torque; And a magnetic field detecting means for detecting the strength of a magnetic field generated by the torque applied to the shaft. The magnetic field detecting means is separated from the shaft, and the magnetic field detecting means is housed in the shaft. It is configured to be detachable from a mounted housing or the like.

The above-mentioned magnetic field detecting means is constituted by a printed board having a magnetic field detecting sensor, a case made of a non-magnetic material and containing the printed board. The above case was filled with a synthetic resin. Further, a magnetic shield was applied to the above case.

[0011]

FIG. 10 is a view for explaining the principle of a torque detector according to the present invention. In the figure, reference numeral 1 denotes a torque detecting shaft (hereinafter, simply referred to as a shaft) which is made of a magnetic material, is rotatably supported, and detects applied torque.
Are provided with magnetized portions 2a and 2b which are perpendicular to the axis and are magnetized over the entire circumference in a direction opposite to each other at a predetermined interval, and the magnetized portions 2a and 2b are always in a balanced state. Yes, and no magnetic field is generated. When a torque as indicated by an arrow is applied to the shaft 1, the balance between the magnetized portions 2a and 2b is lost, and a magnetic field M corresponding to the strength of the torque is generated.

Reference numerals 3a and 3b denote, for example, magnetic field detecting sensors (hereinafter simply referred to as detecting sensors) for detecting a generated magnetic field.
When a torque is applied to the shaft 1 and a magnetic field is generated from the magnetized portions 2a and 2b, an electric signal (voltage or current) or phase corresponding to the strength of the magnetic field is provided. Output the change of Numeral 4 denotes an amplifier for amplifying the above electric signal. The converter 5 converts a change in the electric signal due to the output of the detection sensors 3a and 3b into a torque value by the converter 5, thereby obtaining a linear torque value as shown in FIG. be able to. The means for processing the change in the electric signal by the detection sensors 3a and 3b is not limited to the above, and an appropriate means can be adopted.

[First Embodiment] FIG. 1 is a longitudinal sectional view of a torque detector according to a first embodiment of the present invention, FIG. 2 is an external perspective view of a main part thereof, and FIG. 3 is an exploded perspective view of FIG. is there. The same parts as those of the torque detector described with reference to FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, reference numeral 30 denotes a housing of a transmission of an automobile, for example, and the opening 3
1 are provided, and a screw hole 32 is provided around the opening 31.
Is provided. Numeral 1 denotes a torque detecting shaft which is rotatably mounted in the housing 30 and whose movement in the axial direction is regulated. As shown in FIG. 10, the magnetizing portion 1 is located in the opening 31 of the housing 30. 2a and 2b are provided, and are driven by a transmission gear (not shown).

Reference numeral 10 denotes a substantially portal-shaped and hollow case having an opening 13 at an upper part and a lower part closed, for example, a synthetic resin,
It is formed of a non-magnetic material such as aluminum. The case 10 includes a pair of legs 11a and 11b and a flange 12 provided on the upper outer periphery.
The legs 11a, 11
A pair of guide grooves 14a and 14b each reaching the lower end of b are provided. Reference numeral 15 denotes a screw insertion hole provided in the flange portion 12 corresponding to the screw hole 32 of the housing 30. 1
Reference numeral 6 denotes a closing plate which is made of a non-magnetic material and closes the opening 13 of the case 10, and has connectors 17, and has screw insertion holes 18 at four corners corresponding to the screw insertion holes 15 of the case 10.
Is provided. 19 is a cable connected to the connector 17.

Reference numerals 20a and 20b denote printed circuit boards, on which detection sensors 3a and 3b are mounted at positions corresponding to the magnetized portions 2a and 2b of the shaft 1, respectively. Many electrical components constituting the amplifier and the like are mounted. 21 is a printed circuit board 20
a, 20b and lead wires for connecting the connector 17;
These printed circuit boards 20a, 20b are provided with detection sensors 3a,
3b is turned inward, and both ends of the case 10 are fitted into the guide grooves 14a and 14b from the opening 13 side of the case 10, and the leg 11
a and 11b are inserted and mounted until they reach the lower end.

In the present embodiment configured as described above, the case 1 in which the printed boards 20a and 20b are mounted
0 is inserted into the housing 30 from the opening 31 so that the legs 11a and 11b straddle the shaft 1, and the flange 12 is placed on the housing 30 directly or via packing. Next, the closing plate 16 to which the lead wire 21 is connected to the connector 17 is placed on the case 10, a screw 40 is inserted into each of the screw insertion holes 18, 15, and screwed into the screw hole 32 of the housing 30 to be integrated. , The mounting of the case 10 is completed. At this time, the detection sensors 3a and 3b provided on the printed circuit boards 20a and 20b are magnetized portions 2a and 2b of the shaft 1.
Respectively. Note that, for example, the detection sensors 3a and 3b facing the magnetized portions 2a and 2b of the shaft 1 may be provided on one printed circuit board (for example, 20a), and the other printed circuit board 20b may be omitted.

FIG. 4 shows the torque detector according to the present embodiment, which has various outer diameters (outer diameter 6 m) installed in the housing 30.
6 is a diagram showing the results of measuring the torque applied to the shaft 1 (six types from m to 25 mm). As the diameter of the shaft 1 is smaller, the output voltage with respect to the change in torque is larger, and when the outer diameter of the shaft 1 is larger. It can be seen that the output voltage for a change in torque is small.

In this embodiment, the shaft 1 to which the torque is applied and the sensors 3a and 3b for detecting the torque are completely separated, and the lower part of the case 10 is bifurcated to form the entire circumference of the shaft 1. Is not covered, and the case 10 can be attached and detached from the outside of the housing 30. Therefore, attachment and detachment and maintenance of the case 10 are extremely easy. In addition, the case 1 can also be used under adverse conditions, such as a transmission, an engine, a machine tool, or the like of a high-temperature automobile in which oil is contained, or where water exists or is humid.
0 is externally mounted to position the detection sensors 3a and 3b near the magnetized portions 2a and 2b of the shaft 1, so that the torque applied to the shaft 1 can be reduced without being affected by these adverse conditions. It can be measured accurately.

Since the case 10 has a simple structure and a small size, it does not require a large space for mounting, and can be easily used in the housing 30 having a dense structure. Further, since the lead wires 21 from the printed circuit boards 20a and 20b are taken out to the outside via the connector 17, the wiring work is extremely easy, and the number of parts is greatly reduced, so that the assembly is simple and the cost is greatly increased. Therefore, an inexpensive and highly reliable torque detector can be obtained.

[Second Embodiment] FIG. 5 is a perspective view of a torque detector according to a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, a housing 30 (not shown) is used.
The present invention relates to a torque detector when a shaft 1 for detecting torque is installed at a position (in the back) away from an inner wall surface.

On the closing plate 16 for closing the upper opening of the case 10, a cylindrical connecting portion 16a having a length corresponding to the installation position of the shaft 1 is erected, and an upper end portion of the connecting portion 16a is provided. Is provided with a flange portion 12a having an open upper surface. The opening of the flange portion 12a is closed by a closing plate 16b having a connector 17.
The lead wires 21 of the detection sensors 3a and 3b provided in the case 10 are connected to the connector 17 through the inside of the connecting portion 16a.

In the torque detector constructed as described above, the case is moved from the opening 31 of the housing 20 to the legs 11 thereof.
a and 11b are inserted into the housing 30 so as to straddle the shaft 1, and are installed by fixing the flange portion 12a to the wall surface of the housing 30. At this time, case 10
Detection sensors 3a provided in the legs 11a, 11b of the
3b is arranged opposite to the magnetized parts 2a, 2b from both sides of the shaft 1.

FIG. 6 is a perspective view showing another example of the present embodiment. In this example, the case 10 is formed in a horizontal direction, and one leg (for example, 11a) side of the case 10 is extended upward perpendicularly to the legs 11a and 11b to form a hollow connection portion 16a having a rectangular cross section. Formed in the connecting portion 16a
Corresponds to the installation position of the shaft 1, and a flange portion 12a is provided at the upper end thereof as in the case of the example of FIG. In this example, the opening 31 of the housing 30
The case 10 inserted from the bottom of the case 10 has its legs 11a, 11b.
Is inserted from the lateral direction of the shaft 1 to the top and bottom of the shaft 1. The lead wires 21 of the detection sensors 3a and 3b provided in the case 10
, And the detection sensors 3a and 3b are opposed above and below the magnetized parts 2a and 2b of the shaft 1.

In the torque detector according to the present embodiment, the means for detecting the torque applied to the shaft 1 is the same as in the case of the first embodiment. Even when 1 is installed at a position away from the wall surface of housing 30, the torque applied thereto can be measured easily and reliably. Although FIG. 5 shows a case where the connecting portion 16a is formed in a circular cross section and FIG. 6 shows a case in which the connecting portion 16a is formed in a rectangular cross section, the cross sectional shape of the connecting portion can be appropriately selected. Further, the connecting portion 16a may be of a joint type, or a spacer may be provided so that the length between the case 10 and the flange portion 12a can be adjusted according to the installation position of the shaft 1.

[Third Embodiment] FIG. 7 is a longitudinal sectional view of a torque detector according to a third embodiment, and FIG. 8 is an exploded perspective view thereof. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, case 1
Numeral 0 is formed of a nonmagnetic material into a rectangular parallelepiped shape having a bottom and an opening 13 at the top, and a flange 12 having a screw insertion hole 15 is provided on the outer periphery of the upper end.
On the lower surface of the printed circuit board 20, a magnetized portion 2 of the shaft 1 is provided.
The detection sensors 3a and 3b are mounted side by side in correspondence with a and 2b.

In the present embodiment, the printed circuit board 2
0 is inserted into the case 10 with the detection sensors 3a and 3b facing downward, and held at a predetermined position (holding means is not shown). Then, the case 10 is inserted into the opening 31 of the housing 30 and the flange 12 is
It is mounted on a housing 0 and integrally fixed to the housing 30 by screws 40 together with the closing plate 16 to which the lead wire 21 is connected to the connector 17. At this time, the detection sensors 3 a and 3 b provided on the printed circuit board 20 are
a, 2b.

FIG. 9 shows another example of the present embodiment. In the example of FIG.
Is not provided, the shaft 1 is installed close to the inner wall surface of the housing 30, and the printed circuit board 20 is connected to the detection sensors 3a, 3a.
b is disposed on the side of the opening 13 of the case 10 facing downward,
The flange 12 is fixed to the housing 30 with screws 40 with the opening 13 of the case 10 facing downward, and the detection sensors 3a and 3b are connected to the magnetized portion 2 via the wall surface of the housing 30.
a, 2b. The example of FIG. 9B is almost the same as that of FIG.
Is provided, the case 10 is inserted downward into the housing 30, and the flange 12 is fixed to the inner wall surface of the housing 30 with screws 30.

The operation and effect of this embodiment are the same as those of the first embodiment.
However, since the case 10 can have a simpler structure and the printed circuit board 20 can be a single sheet, the number of components can be further reduced.
The cost can be further reduced.

[Embodiment 4] While the embodiment of the present invention has been described above, the following embodiment is further provided. (1) In the first to third embodiments, the magnetized portion 2 provided on the shaft 1
One detection sensor 3a, 3b for each of a and 2b
Is shown, but the number of detection sensors 3a and 3b provided corresponding to each of the magnetized portions 2a and 2b may be one as described above, and more detection sensors may be provided. Is also good. Increasing the number of detection sensors respectively corresponding to the magnetized portions 2a and 2b can improve the torque detection accuracy.

(2) In each embodiment, the printed circuit board 20 having the detection sensors 3a and 3b is disposed in the hollow case 10 and the lead wire 21 is connected to the connector 17
Although the case of taking out to the outside through is shown, the hollow portion of the case 10 may be filled with a synthetic resin after the printed circuit board 20 is provided. In this case, in the second embodiment,
The synthetic resin may be filled up to the upper part of the connecting portion 16a. Further, the case 10 may be integrally formed of a synthetic resin by inserting the printed circuit board 20. Thus, the printed circuit board 20 can be reliably held at a predetermined position in the case 10 and at the same time, water or the like can be prevented from entering the case 10.

(3) Further, in order to avoid the influence of the external magnetic field, the case 10 is provided with a part except for the detection sensors 3a and 3b.
For example, the case 10 may be provided with a magnetic shield by bonding a permalloy tape or applying a magnetic shield paint.
The portion excluding 3b may be accommodated in the magnetic shield case.

[0032]

The torque detector according to the present invention is provided with a shaft having a magnetized portion which is magnetized so as to generate a magnetic field corresponding to the intensity of the applied torque, and is disposed near the shaft. Magnetic field detecting means for detecting the strength of the magnetic field generated by the torque applied to the shaft; the shaft and the magnetic field detecting means are separated, and the magnetic field detecting means is detachable from a housing or the like in which the shaft is housed As a result, it is possible to reliably detect torque even in a high temperature environment or in an environment where water or oil is present, and to obtain an inexpensive and highly reliable torque detector having a simple and compact structure. be able to.

Further, since the magnetic field detecting means is constituted by a printed circuit board having a magnetic field detecting sensor and a case made of a non-magnetic material and accommodating the printed circuit board, the magnetic field detecting means can be downsized and can be attached to and detached from a housing or the like. Extremely easy.

Further, since the case is filled with the synthetic resin, the magnetic field detection sensor can be reliably held at a predetermined position, and the entry of water or the like into the case can be prevented. Furthermore, since the case is provided with a magnetic shield, the magnetic field and thus the torque can be measured with high accuracy without being affected by an external magnetic field.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a torque detector according to Embodiment 1 of the present invention.

FIG. 2 is an external perspective view of a main part of FIG.

FIG. 3 is an exploded perspective view of FIG.

FIG. 4 is a diagram showing a relationship between a torque applied to shafts having different outer diameters by the torque detector according to the first embodiment and an output voltage from a detection sensor.

FIG. 5 is a perspective view of a torque detector according to Embodiment 2 of the present invention.

FIG. 6 is a perspective view of another example of the second embodiment.

FIG. 7 is a longitudinal sectional view of a torque detector according to Embodiment 3 of the present invention.

FIG. 8 is an exploded perspective view of FIG. 7;

FIG. 9 is a longitudinal sectional view of another example of the third embodiment.

FIG. 10 is a principle explanatory diagram of a torque detector according to the present invention.

FIG. 11 is a diagram showing a relationship between an output voltage and a torque by the torque detector of FIG. 10;

[Explanation of symbols]

 1 shaft 1a main shaft 2a, 2b magnetized part 3a, 3b magnetic field detection sensor 10 case 16 closing plate 16a connecting part 20, 20a, 20b printed circuit board 30 housing 35 casing 31, 36 opening

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaharu Baba 1-1171 Tenjin-cho, Kodaira-shi, Tokyo Koyo Electronics Industry Co., Ltd. (72) Inventor Toshiaki Yatani 1-1171 Tenjin-cho, Kodaira-shi, Tokyo Mitsuyo Denshi Industrial Co., Ltd.

Claims (4)

[Claims] 1. A shaft having a magnetized portion which is magnetized so as to generate a magnetic field corresponding to the magnitude of an applied torque, and a shaft arranged near the shaft and provided with a torque applied to the shaft. Magnetic field detecting means for detecting the intensity of the generated magnetic field, wherein the shaft and the magnetic field detecting means are separated, and the magnetic field detecting means is configured to be detachable from a housing or the like in which the shaft is housed. A torque detector. 2. The torque detector according to claim 1, wherein the magnetic field detecting means comprises a printed circuit board having a magnetic field detecting sensor and a case made of a non-magnetic material and containing the printed circuit board. 3. The torque detector according to claim 2, wherein the case is filled with a synthetic resin. 4. The torque detector according to claim 2, wherein a magnetic shield is applied to the case.