JPH06258158A - Magnetostriction-type torque sensor - Google Patents

Abstract

PURPOSE:To prevent the position deviations of the magnetic anisotropic part of a magnetostriction shaft and a coil in the axial direction, to detect torque in high accuracy, to prevent the intrusion of oil the like, and to eliminate the erroneous operation of a torque detecting circuit. CONSTITUTION:Elastic spacers 14 and 14 are provided between a casing 1 an both side surfaces of a resin case 6. Thus, the change in size of the resin case 6 caused by the deterioration in time is absorbed, and the position deviations of magnetic anisotropy parts 2A and 2B of a magnetostriction shaft 2 and each core member 7 (each coil 9) in the axial direction are prevented. The gap between the casing 1 and both side edges of the resin case 6 is eliminated, and the intrusion of water, oil and the like is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive torque sensor suitable for use in detecting torque generated in an output shaft of an automobile engine, for example.

[0002]

2. Description of the Related Art Generally, a cylindrical casing, a magnetostrictive shaft rotatably supported by the casing and having a magnetically anisotropic portion formed therein, and a magnetostrictive shaft are provided in the casing so as to surround the outside thereof. Magnetostriction consisting of a pair of core members and an exciting and detecting coil provided in each core member and wound around a coil bobbin in each core member so as to detect a torque acting on the magnetostrictive shaft as an electric signal. Torque sensors are known.

By the way, in this type of conventional torque sensor, each core member provided in the casing is made of a brittle magnetic material such as ferrite.
There is a problem that the core member inside the casing may be damaged by an external impact, and the durability cannot be improved.

Therefore, in order to solve the above-mentioned problems, the applicant of the present invention has previously disclosed in Japanese Patent Application No. 4-341578 that a cylindrical core member, a coil bobbin, a coil, etc. are integrally formed in a resin case by resin molding. In this state, we proposed a magnetostrictive torque sensor in which a resin case is arranged in a casing together with a core member and the like.

In the torque sensor according to this prior art, since the core member and the like are surrounded by the resin case, it is possible to prevent the core member from being displaced in the casing due to external vibration or shock. There is an advantage that damage accidents and the like can be eliminated.

[0006]

By the way, the magnetostrictive torque sensor according to the above-mentioned prior art, when used in a vehicle or the like, may be exposed to severe vibration or temperature change from the outside, or water may enter. However, there is an unsolved problem that the components of the torque sensor deteriorate with time and the dimensions of the components change. In particular, since the resin case is formed of a resin material, the resin case may change in size due to temperature change, deterioration over time, etc. When the axial size changes, each core member (each coil) becomes a magnetostrictive shaft. The magnetic anisotropy part of will be displaced in the axial direction,
There is an unsolved problem that the torque detection sensitivity decreases.

Further, when the axial dimension of the resin case changes, a gap is generated between the resin case and the casing, so that the resin case rattles in the axial direction of the casing, and the core inside the resin case Members may be damaged by this vibration. Then, in this case, there is an unsolved problem that the magnetic field leaks from the damaged portion and a stable torque detection signal cannot be output.

On the other hand, since a radial gap is formed between the inner peripheral surface of the casing and the resin case due to a dimensional error or the like, water, oil, or the like that has entered the casing from each bearing portion side of the casing is May reach into the gap. In this case, there is an unsolved problem that a short circuit is likely to occur due to the intrusion of water, oil, etc., the detection circuit does not operate correctly, and the coils are broken.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention is such that the resin case rattles in the casing or the core member (coil It is an object of the present invention to provide a magnetostrictive torque sensor capable of preventing the position deviation of () in the axial direction and detecting the torque with high accuracy over a long period of time.

[0010]

In order to solve the above-mentioned problems, the structure adopted by the present invention has a cylindrical casing and a magnetic anisotropy rotatably supported in the casing via a bearing. A magnetostrictive shaft having a portion formed therein, and at least a pair of core members, a coil bobbin, which are provided in the casing so as to surround the outer peripheral side of the magnetostrictive shaft,
A cylindrical resin case in which the excitation and detection coils are integrally surrounded by a resin mold, and a plurality of the resin cases are disposed at both axial ends of the resin case and are elastically deformed between the resin case and the casing. Elastic spacers.

[0011]

With the above construction, since each elastic spacer is pressed against the end faces of the resin case in the casing in an elastically deformed state, even if the dimensions of the resin case change due to temperature change or deterioration over time, this is prevented. Can be absorbed by each elastic spacer,
It is possible to prevent axial misalignment between the magnetic anisotropy portion of the magnetostrictive shaft and the core member (coil), and absorb the vibration play of the resin case in the casing by each elastic spacer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

First, FIGS. 1 and 2 show a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a cylindrical casing fixed to a vehicle body (not shown) of an automobile. The casing 1 has stepped bearing portions 1A, 1A at both axial ends thereof. An annular positioning step portion 1B that protrudes radially inward is formed in a portion adjacent to the side bearing portion 1A. Further, a connector insertion hole 1C penetrating the casing 1 is radially formed in an axially intermediate portion of the casing 1, and an outer periphery of the connector insertion hole 1C is radially outward from the casing 1. An annular connector mounting portion 1D is formed so as to project inward. A male screw portion 1D1 is formed on the outer peripheral surface of the connector mounting portion 1D.

Reference numeral 2 denotes a magnetostrictive shaft, which is rotatably supported by bearings 3 provided on each bearing portion 1A of the casing 1, and is, for example, a propeller shaft, an output shaft, a drive shaft, etc. Is part of. The magnetostrictive shaft 2 is formed of, for example, a magnetostrictive material such as chrome molybdenum steel into a cylindrical shape,
Magnetically anisotropic portions 2A and 2B are formed in the intermediate portion in the axial direction with a certain distance therebetween. Here, one magnetic anisotropic portion 2A has a large number of one-side slits 4, 4, ... On the outer peripheral surface of the magnetostrictive shaft 2 and downward 45. And the other magnetic anisotropic portion 2B is formed on the outer peripheral surface of the magnetostrictive shaft 2 by a large number of other side slits 5, 5, ...
Up 45. It is formed by engraving at an angle of.

Reference numeral 6 denotes the magnetic anisotropic portion 2 of the magnetostrictive shaft 2.
1 shows a resin case provided in the casing 1 so as to surround the area from A to the magnetic anisotropy portion 2B from the outside, and the resin case 6 is shown in FIG. The coil bobbin 8 and each coil 9 are integrally formed by resin molding. The resin case 6 is formed with an annular convex portion 6B protruding inward in the radial direction at an axially intermediate portion of the tubular portion 6A, and both ends of the tubular portion 6A shown in FIG.
As shown in FIG. 6, annular retaining portions 6C, 6C having a triangular cross section and protruding inward in the radial direction are formed. Each core member 7 described later is arranged between the annular convex portion 6B and each annular retaining portion 6C, and the core member 7 is axially positioned.

Further, in the cylindrical portion 6A of the resin case 6, terminal pin holes 6D, 6D, ... (2) located on both sides of the annular convex portion 6B and communicating with the connector insertion hole 1C of the casing 1 are provided.
A total of four holes are provided, two for each, and two for each terminal pin 10, which will be described later, are inserted into each of the terminal pin holes 6D. Further, a chamfered portion 6E is formed at an axially intermediate portion of the resin case 6 on the outer peripheral surface side where each terminal pin hole 6D is located, and the chamfered portion 6E has a four-terminal connector 11 described later.
The tip end side of is contacted.

Reference numerals 7 and 7 denote core members provided in the resin case 6, and each core member 7 is a pair of core pieces 7A and 7A formed from a magnetic material such as ferrite in an L-shaped cross section. By abutting like this, it is formed into a tubular shape.
As shown in FIG. 2, taper surface portions 7B, 7B are formed on the outer peripheral surface of one end of each core piece 7A, and each taper surface portion 7B is surrounded from the outside by each annular retaining portion 6C of the resin case 6. ing. Further, a V-shaped slit 7C communicating with the terminal pin hole 6D of the resin case 6 is formed in the core piece 7A of each core member 7 located near the annular convex portion 6B of the resin case 6, and the slit 7C is formed. Each terminal pin 10 described later is inserted therein. Further, a minute air gap is formed between each core member 7 and the magnetostrictive shaft 2.

Reference numerals 8 and 8 denote a pair of coil bobbins provided on the inner peripheral side of each core member 7, respectively.
Is composed of a cylindrical shaft portion 8A made of an insulating resin material, and annular collar portions 8B, 8B formed so as to extend radially outward from both sides of the shaft portion 8A.

Reference numerals 9 and 9 denote shaft portions 8A of the respective coil bobbins 8.
2 shows an exciting and detecting coil wound around the outer peripheral surface of the coil. One end and the other end of the winding (not shown) of each coil 9 is electrically connected to each terminal pin 10 by means such as soldering. It is connected to the. Each of the coils 9 is a detection circuit including a bridge circuit provided outside the casing 1, an oscillator, an operational amplifier, etc. (none of which is shown).
Is connected via a 4-terminal connector 11. Here, each coil 9 serves as both an exciting coil that is excited by a high-frequency voltage from an oscillator to generate a magnetic flux, and a detecting coil that detects a magnetic flux flowing in a magnetic circuit.

.. are provided so as to project from the annular flange portion 8B of each coil bobbin 8 in pairs, two in total in a radially outward direction.
Shows two terminal pins (only two are shown), and each terminal pin 1
As shown in FIG. 2, the reference numeral 0 indicates the cylindrical insulator 1 inside the slit 7C of each core member 7 and each terminal pin hole 6D of the resin case 6.
Each terminal pin 1 is arranged so as to penetrate through 0A.
0 projects into the connector insertion hole 1C of the casing 1.

Reference numeral 11 designates a four-terminal connector, and the four-terminal connector 11 is, as shown in FIG.
A1, a connector main body 11A formed of an insulating material in the form of a stepped column having an annular groove 11A2 on the tip side, and a bag-shaped fixing nut 11B movably disposed on the outer peripheral side of the annular step 11A of the connector 11A. And a total of four pin insertion portions 11C, 11C, ... (Only two are shown) into which the respective terminal pins 10 are inserted are provided on the tip end side of the connector body 11A, and the annular groove portion 11A2 is provided with Is O-ring 11D
Is installed.

Here, the terminal pins 10 protruding from the annular flange portion 8B of the coil bobbins 8 are inserted into the pin insertion portions 11C, and the coils 9 and an external detection circuit are electrically connected. Connected. In addition, the four-terminal connector 11
Is the connector body 1 in the connector insertion hole 1C of the casing 1.
1A is inserted, each terminal pin 10 is inserted into each pin insertion portion 11C, and then the fixing nut 11B is screwed onto the male screw portion 1D1 of the connector mounting portion 1D to be fixed to the casing 1. There is. Then, the annular groove portion 11
The O-ring 11D attached to A2 prevents water, oil, etc. from entering from the outside of the casing 1 between the chamfered portion 6E of the resin case 6 and the tip end surface of the four-terminal connector 11.

Reference numeral 12 denotes an annular fixing member provided on the other side of the casing 1 so as to face the positioning step portion 1B of the casing 1 in the axial direction, and the fixing member 12 contacts the bearing 3 on the other side. This allows the resin case 6 to cover the casing 1.
It is what is fixed inside.

That is, when fixing the resin case 6 and the like in the casing 1, first, one side, which will be described later, is made so as to contact the positioning step portion 1B of the casing 1 from the other side of the casing 1 toward one side. Elastic spacer 14 is inserted, then the resin case 6 is inserted so as to contact the elastic spacer 14, and the elastic spacer 14 on the other side is inserted so as to contact the other end side of the resin case 6. After that, the fixing member 12 is inserted from the other side of the casing 1 and the bearing 3 on the other side is press-fitted into the bearing portion 1A.
Position inside. At this time, each elastic spacer 14 is pressed between the resin case 6 and the casing 1, and is sandwiched in an elastically deformed state.

Reference numerals 13 and 13 denote C-rings. The C-rings 13 position the magnetostrictive shaft 2 and the bearings 3 and 3 relative to each other. The C-rings 13 are located on the inner ring side of the bearings 3. Is positioned in the axial direction of the magnetostrictive shaft 2, and the magnetostrictive shaft 2 is held so as to be rotatable relative to the casing 1. As a result, the slits 4 and 5 of the magnetic anisotropic portions 2A and 2B of the magnetostrictive shaft 2 and the core members 7 are formed.
(Each coil 9) is made to oppose in a radial direction via a minute air gap.

Reference numerals 14 and 14 denote elastic spacers formed of, for example, fluorocarbon rubber in an annular shape. Of the elastic spacers 14, one elastic spacer 14 is the resin case 6.
Between one side surface, the end surface of the core member 7 on one side and the positioning step portion 1B of the casing 1, the other elastic spacer 14 is the other side surface of the resin case 6, the end surface of the core member 7 on the other side, and the fixing member 12. And is pressed against both ends of the resin case 6 in an elastically deformed state.

The magnetostrictive torque sensor according to the present embodiment has the above-mentioned structure, and when an AC voltage is applied to each coil 9 from the oscillator of the detection circuit, the magnetic flux generated from each coil 9 causes each core member 7 to move. A magnetic circuit extending over the magnetostrictive shaft 2 is formed. When torque acts on the magnetostrictive shaft 2, the inductance of each coil 9 changes due to the slits 4 and 5. Therefore, a detection signal corresponding to the torque acting on the magnetostrictive shaft 2 from a bridge circuit including each coil 9. Can be obtained.

Thus, according to this embodiment, the resin case 6
Located on both axial ends of the casing 1 and the resin case 6
Since the respective elastic spacers 14 are provided between and, and the resin case 6 is positioned in the casing 1 via the fixing member 12 or the like so as to elastically deform each elastic spacer 14 in the casing 1, The elastic force of the elastic spacer 14 allows the resin case 6 to be pressed from both sides in the axial direction of the casing 1 with a uniform force, so that the resin case 6 can be accurately opposed to the magnetostrictive shaft 2 in the casing 1.

Further, a torque sensor is mounted on an automobile or the like,
Even when the resin case 6 changes in size in the axial direction due to temperature change, deterioration over time, or the like, the elastic cover force of each elastic spacer 14 can absorb the dimensional change at this time, and the position of the resin case 6 relative to the casing 1 shifts. Can be prevented.

Thus, according to this embodiment, the axial misalignment between the magnetic anisotropic portions 2A and 2B of the magnetostrictive shaft 2 and the core members 7 (each coil 9) in the resin case 6 is maintained for a long period of time. It is possible to prevent the vibration of the resin case 6 from occurring in the axial direction of the casing 1 and solve the problem that the core members 7 and the like in the resin case 6 are damaged.

Further, the resin case 6 is provided with annular retaining portions 6C on both ends of each tubular portion 6A so as to surround each core member 7 from the outside and prevent each core member 7 from retaining. . Therefore, it is not necessary to form the resin case 6 so as to completely cover the end surface of each core member 7, and the volume (volume) of the resin case 6 can be reduced.
The material cost can be reduced, and the dimensional change of the resin case 6 due to deterioration over time can be effectively reduced, and the positional deviation of the resin case 6 with respect to the casing 1 can be reliably reduced.

Further, the positioning step portion 1 of the casing 1
B, since the elastic spacers 14 liquid-tightly seal between the fixing member 12 and both end sides of the resin case 6 and the end faces of the core members 7, water, oil, etc. are kept from the inner peripheral surface of the casing 1 and the resin. It is possible to prevent invasion into the space between the case 6 and each other, eliminate a short-circuit accident between the terminal pins 10, and solve problems such as disconnection of the coil 9.

Therefore, in the present embodiment, even when the dimensions of the resin case 6 change due to temperature changes or the like, the resin case 6 rattles in the casing 1 and the core members 7 (each coil 9) move in the axial direction. Positional deviation can be prevented, and torque can be detected with high accuracy for a long period of time.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do
The feature of this embodiment is that the resin case 21 provided in the casing 1 is formed in an E-shaped cross section from the cylindrical portion 21A, the annular convex portion 21B and the respective annular flange portions 21C, and the annular convex portion 21B and the respective annular flange portions are formed. The respective core members 22 are arranged between the portions 21C and the annular elastic spacers 23 are elastically abutted against the end faces of the annular collar portions 21C.

Here, the resin case 21 is provided with each annular flange 21.
Except for C, it is formed in the same manner as the resin case 6 described in the first embodiment, and each terminal pin hole 21D and chamfered portion 21 is formed.
Have E. Then, each annular flange portion 21C of the resin case 21 radially projects from both axial ends of the tubular portion 21A toward the magnetostrictive shaft 2, and surrounds the end surface of each core member 22 with the annular convex portion 21B. . In addition, each core member 22
Is formed by abutting the core pieces 22A, 22A having an L-shaped cross-section, as in the core members 7 described in the first embodiment, and has a V-shaped slit 22B. Further, each elastic spacer 23 is formed similarly to the elastic spacer 14 described in the first embodiment, and elastically positions the resin case 21 in the casing 1.

Thus, in this embodiment having such a structure, it is possible to obtain substantially the same operational effects as those of the first embodiment, but in this embodiment, in particular, each core member 22 is provided in the resin case 21. Etc. can be completely surrounded, and each core member 22 can be protected more effectively against external vibration and the like.

In the above embodiments, the terminal pins 10 are inserted into the pin insertion portions 11C of the 4-terminal connector 11 in order to connect the coils 9 to the detection circuit. The present invention is not limited to this, and the detection circuit may be attached to the outside of the casing 1 and the coil lead wire may be directly connected to the detection circuit by means of soldering or the like.

Further, in each of the above embodiments, the two-coil type magnetostrictive coil sensor has been described as an example, but the present invention is not limited to this, and may be used in a four-coil type magnetostrictive torque sensor, for example. . In this case, the four core members may be integrally resin-molded with a resin case.

Furthermore, in each of the above-described embodiments, the case where the invention is used for detecting the torque of the automobile engine has been described as an example, but the invention can be used for detecting other torque such as the rotational torque of the electric motor.

[0041]

As described above in detail, according to the present invention, elastic spacers are provided between the casing and both ends of the resin case, and the resin case is positioned in a state where the elastic spacers are elastically deformed. Therefore, even if a dimensional change occurs in the resin case due to temperature change or deterioration over time, the dimensional change of the resin case can be absorbed by each elastic spacer, and the core member or coil inside the resin case It is possible to reliably prevent axial displacement with respect to the magnetic anisotropic portion of the magnetostrictive shaft. Further, the vibration and rattling of the resin case inside the casing can be buffered by the elastic force of each elastic spacer, and the core member and the coil bobbin can be reliably prevented from being damaged.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a magnetostrictive torque sensor according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part in FIG.

FIG. 3 is a vertical sectional view showing a magnetostrictive torque sensor according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Casing 2 Magnetostrictive shaft 6,21 Resin case 7,22 Core member 8 Coil bobbin 9 Coil 14,23 Elastic spacer

Claims (1)

[Claims] 1. A tubular casing, a magnetostrictive shaft rotatably supported in the casing via bearings and having a magnetic anisotropic portion, and the casing so as to surround the outer peripheral side of the magnetostrictive shaft. A cylindrical resin case which is provided inside and surrounds at least a pair of core member, coil bobbin, excitation and detection coils integrally by resin molding, and the resin case and the casing which are located at both axial ends of the resin case. A magnetostrictive torque sensor including a plurality of elastic spacers disposed between and in an elastically deformed state.