JP5947042B2 - Rotation sensor unit - Google Patents

Description

  The present invention relates to a rotation sensor unit that includes a magnetic rotation sensor in a housing and can be incorporated in another device using the housing and a shaft.

  2. Description of the Related Art Conventionally, a magnetic rotation sensor capable of detecting at least one of a rotation angle and a rotation speed has been used for rotation control of a rotation shaft such as a motor shaft, an axle, and a roll shaft. The magnetic rotation sensor is arranged such that a magnetic detection element that detects a change in a magnetic field is stationary with respect to a rotation shaft, and the rotation is converted into the change in the magnetic field by an encoder that rotates integrally with the rotation shaft. It has become.

  Among them, there is one that is provided as a rotation sensor unit that includes a shaft body, a housing, a cover that covers one assembly port in the axial direction of the housing, and a plurality of rolling bearings that support the shaft body with respect to the housing. The bearing, the encoder, and the magnetic detection element are disposed in an inner space formed between the inner periphery of the housing, the shaft body, and the lid. The user can incorporate the rotation sensor unit into the other device by simply connecting the rotation shaft of the other device to the shaft body and attaching the housing to the wall surface that rotates relative to the rotation shaft of the other device.

  In a conventional rotation sensor unit, an encoder made of a permanent magnet is arranged on one end face in the axial direction of a shaft body, and a magnetic detection element is arranged in the center of the lid with a gap in the axial direction from the encoder. The other end surface in the axial direction of the shaft body is exposed in the axial direction from the housing in order to enable connection with the rotation shaft of another device (Patent Document 1).

JP 2009-53093 A

  However, in the rotation sensor unit as in Patent Document 1, since the encoder arranged on the end surface of the shaft body and the magnetic detection element of the lid are opposed to each other with a gap in the axial direction, the total length of the rotation sensor unit in the axial direction is increased. In order to shorten and make a compact design, it is necessary to reduce the distance between the bearings of a plurality of rolling bearings. When an external force of radial load is applied to the other axial end of the shaft body, moment load acts on the plurality of bearings. When the distance between the bearings is reduced, the load applied to the rolling elements of the bearing increases. As a result, there arises a problem that it is difficult to allow a large radial load to the shaft body.

  Note that reducing the thickness of the lid is advantageous for shortening the overall length of the rotation sensor unit. However, when the lid is used as a magnetic shield of the magnetic detection element, the magnetic shield effect by the lid is reduced, which is not preferable.

  Accordingly, the problem to be solved by the present invention is to increase the radial load allowed at the other axial end of the shaft body without increasing the total axial length of the rotation sensor unit.

  The present invention that achieves the above object includes a shaft body, a housing, a cover that covers one of the housings in the axial direction, a first rolling bearing, a second rolling bearing, and a magnet that detects a change in a magnetic field. A detection element; and an encoder that rotates integrally with the shaft body and converts the rotation into a change in the magnetic field, the first rolling bearing and the second rolling bearing that support the shaft body, and the magnetic In the rotation sensor unit in which the detection element and the encoder are disposed in an inner space formed between the inner periphery of the housing, the shaft body, and the lid, the encoder includes the first rolling bearing and the A configuration is adopted in which the magnetic detection element is disposed between the second rolling bearing and the encoder in a radial direction. In the present invention, the “axial direction” means a direction along the central axis of the shaft body, and the “radial direction” means a direction perpendicular to the central axis of the shaft body.

  That is, if the encoder is disposed between the first rolling bearing and the second rolling bearing, and the magnetic detection element is disposed at a position facing the encoder in the radial direction, the magnetic detection element is provided between the lid and the end surface of the shaft body. , Encoder and gap arrangement space is not required. If the distance between the bearings of the first rolling bearing and the second rolling bearing is increased, the moment load supporting capacity of both rolling bearings will be improved, so the radial load allowed at the other axial end of the shaft body will be increased. be able to. This increase in the distance between the bearings makes use of the arrangement space that is no longer necessary, and therefore there is no need to increase the total axial length of the rotation sensor unit.

  For example, a sensor case having a recess opened toward the encoder is provided, and a side wall and a bottom wall of the recess formed of a magnetic material include a magnetic-electric conversion circuit unit included in the magnetic detection element. Covering from the housing side, it is preferable that the shaft body, the race ring and rolling element of the first rolling bearing, and the race ring and rolling element of the second rolling bearing are made of a magnetic material. If the sensor case recess is opened toward the encoder, the magnetic field emitted from the encoder can be applied to the conversion circuit portion even if the magnetic-electric conversion circuit portion of the magnetic detection element is disposed in the recess made of magnetic material. The side peripheral wall and the bottom wall of the recess made of magnetic material can be a magnetic shield that covers the conversion circuit portion from the housing side. Since the shaft body, the bearing ring and rolling element of the first rolling bearing, and the bearing ring and rolling element of the second rolling bearing are made of magnetic material, they serve as magnetic shields that cover the conversion circuit section from the shaft body side, and between the two bearings. It also serves as a magnetic shield that shields the encoder arranged at the external magnetic field.

  As described above, the magnetic-electrical conversion circuit part and the encoder of the magnetic detection element can be shielded from the external magnetic field by the recess of the sensor case, the shaft body, the first rolling bearing and the second rolling bearing. A lid and a housing can be adopted. Even when the lid and the housing are formed of a magnetic material, the lid and the housing can be made thin.

  For example, the encoder is composed of an annular magnet. This encoder can be fixed between the inner ring of the first rolling bearing and the inner ring of the second rolling bearing. Between both inner rings, a shaft body can be used for the radial positioning of the encoder, and the inner ring can be used for the axial positioning.

  More specifically, the shaft body includes a spacer portion that maintains an axial interval between an inner ring of the first rolling bearing and an inner ring of the second rolling bearing, and the encoder is configured to have a diameter by the spacer portion. It is preferably supported in the direction. The spacer portion that keeps the distance between the inner rings can be used for supporting the encoder in the radial direction, thereby preventing the encoder from being unnecessarily compressed.

  For example, the bearing seat for fitting the outer ring of the first rolling bearing includes an inner diameter surface formed on the lid and an inner diameter surface formed on the housing. The inner diameter surface of the lid can be used for fitting the outer ring. In this case, misalignment between the lid and the housing can be prevented by fitting the outer ring to the inner diameter surface of the housing.

  As described above, the present invention eliminates the need for a space for arranging the magnetic detection element, encoder, and gap between the lid and the end surface of the shaft body by adopting the above-described configuration. Without increasing the distance, the distance between the bearings of the first rolling bearing and the second rolling bearing can be increased, and the radial load allowed on the other axial end of the shaft body can be increased.

(A) is sectional drawing which showed the whole structure of the rotation sensor unit which concerns on embodiment with the plane containing a bearing central axis, (b) is the elements on larger scale of the bb line drawn to said (a), (C) is the fragmentary expanded sectional view of the cc line of said (b). Sectional drawing which shows the example of direction change of the magnetic detection element of FIG.

  A rotation sensor unit (hereinafter simply referred to as “this rotation sensor unit”) according to a first embodiment of the present invention will be described with reference to FIG. As shown in the figure, the rotation sensor unit includes a shaft body 1, a housing 2, a lid 3 that covers one of the housing 2 in the axial direction, and a first rolling bearing 4 (hereinafter referred to as a first bearing 4). And a second rolling bearing 5 (hereinafter referred to as the second bearing 5), a magnetic detection element 6, and an encoder 7.

  The housing 2 is composed of a bearing housing that is open in both axial directions and has an inner diameter surface 8 that forms one axially-incorporating port and a shoulder 9 that forms the other axial hole in the axial direction.

  The other end portion in the axial direction of the shaft body 1 is given an appropriate protruding length from the housing 2 to the other axial direction. A rotating shaft (not shown) of another device can be connected to the other axial end of the shaft body 1. An oil seal 10 is attached to the inner diameter surface of the shoulder 9.

  The first bearing 4 and the second bearing 5 that support the shaft body 1 with respect to the housing 2 and the lid 3, the magnetic detection element 6 that detects a change in the magnetic field, and the shaft body 1 rotate together, and the rotation is performed. The encoder 7 that converts the change in the magnetic field is disposed in an inner space formed between the inner periphery of the housing 2, the shaft body 1, and the lid 3.

  The encoder 7 is disposed between the first bearing 4 and the second bearing 5, and the magnetic detection element 6 is disposed at a position facing the encoder 7 in the radial direction.

  A mounting flange 11 is formed on the outer periphery of the housing 2. The housing 2 can be attached to the wall surface by screwing the attachment flange 11 to a wall surface (not shown) that rotates relative to the rotation shaft of another device.

  Each of the first bearing 4 and the second bearing 5 includes one inner ring 12 and one outer ring 13, and the rolling elements 14 are incorporated in a single row. These bearings 4 and 5 are appropriately provided as long as the magnetic detection element 6 and the encoder 7 can be arranged as described above and the shaft body 1 can be supported both in the axial direction and in the radial direction with respect to the housing 2. The ball bearings are not limited to those shown in the illustrated example. The same bearing is used for the first bearing 4 and the second bearing 5 in the illustrated example, and the space between the inner ring 13 and the outer ring 12 is sealed with a seal 15. The outer ring 12 and the inner ring 13 are non-separable.

  The lid 3 includes a central portion 16 that faces one axial end surface of the shaft body 1 in the axial direction and receives the side surface of the outer ring 13 of the first bearing 4 in the axial direction, and an outer peripheral portion 17 that surrounds the central portion 16. Become. The lid 3 can be attached to the housing 2 by screwing the outer peripheral portion 17 to the housing 2 from one axial direction. Of the one side surface of the housing 2 in the axial direction, the portion covered by the lid 3 from the one axial direction is protected by the fastening surface of the mounting flange 11 and the fastening surface of the other device together with the lid 3 and the screw member 18. Recessed in the direction. A space between the outer peripheral portion 17 and the housing 2 is sealed by an O-ring 19.

  The inner diameter surface 8 of the housing 2 continues to the shoulder 9. A bearing seat into which the outer ring 13 of the second bearing 5 is fitted has an inner diameter surface 8. The central portion 16 of the lid 3 is recessed in the axial direction from the contact surface between the outer peripheral portion 17 and the housing 2. A bearing seat into which the outer ring 13 of the first bearing 4 is fitted includes an inner diameter surface 20 formed on the outer peripheral portion 17 of the lid 3 and an inner diameter surface 8 of the housing 2. The inner ring 12 of the first bearing 4 and the inner ring 12 of the second bearing 5 are respectively fitted to the shaft body 1.

  The magnetic detection element 6 includes a magneto-electric conversion circuit unit 21 (hereinafter referred to as a conversion circuit unit 21), and includes an element that detects a change in a magnetic field. The encoder 7 is composed of a permanent magnet that rotates integrally with the shaft body 1 and converts the rotation into the change of the magnetic field. The rotation sensor composed of the magnetic detection element 6 and the encoder 7 may be a magnetic sensor that can measure a desired physical quantity related to a rotational motion such as a rotational angle, a rotational speed, and a rotational speed.

  The conversion circuit unit 21 includes a circuit that converts a change in magnetic field in a specific direction into an analog signal. For example, as the magnetic detection element 6, any one of the radial component of the magnetic flux density emitted from the encoder 7, the tangential component with respect to the circumference around the center axis of the bearing, and the axial component is detected by the conversion circuit unit 21. It is possible to employ one that calculates. The magnetic detection element 6 in the illustrated example is an IC in which, in addition to the conversion circuit unit 21, a circuit for converting an analog signal into an output signal of a digital signal, a signal amplification circuit, an arithmetic circuit, and the like are appropriately incorporated.

  The encoder 7 is an annular permanent magnet that is unipolarly magnetized in the radial direction. When a material having anisotropy in the radial direction is magnetized, the magnetization strength can be increased. The magnetic field applied to the conversion circuit unit 21 by the encoder 7 changes according to the rotation angle while rotating integrally with the shaft body 1.

  The shaft body 1 has a spacer portion 22 that maintains an axial interval between the inner ring 12 of the first bearing 4 and the inner ring 12 of the second bearing 5. The inner ring 12 of the first bearing 4 abuts against the spacer portion 22 from one axial direction, and the inner ring 12 of the second bearing 5 abuts against the spacer portion 22 from the other axial direction. A metal core 23 is fitted over the inner diameter surface of the encoder 7 and the inner diameter side ends of both side surfaces. The cored bar 23 is fitted to the outer diameter surface of the spacer portion 22. The encoder 7 is supported in the radial direction by the spacer portion 22 via the core metal 23. The axial position of the encoder 7 can be determined only by the fitting to the spacer portion 22, by only the axial holding by the inner rings 12, 12, or in combination. The encoder 7 is fixed between the inner ring 12 of the first bearing 4 and the inner ring 12 of the second bearing 5 by these radial support and axial positioning.

  In addition, the spacer part 22 is not limited to what consists of the shoulder formed in the shaft body 1 like illustration, but can also be comprised by the inner ring | wheel spacer fitted to the shaft body 1. FIG. The metal core 23 may be omitted when the encoder 7 is directly fitted or when there is no problem even if the encoder 7 is directly sandwiched between the inner rings 12. The spacer portion 22 can be omitted. For example, the encoder 7 can be an inner ring spacer. Further, when the first bearing 4 and the second bearing 5 are constituted by one double row inner ring and two outer rings, if the inner diameter of the encoder 7 is made larger than the track, the central portion in the axial direction of the double row inner ring It is also possible to fit the encoder 7 to the above. When the encoder 7 is fixed between the inner rings 12 and 12 as in the illustrated example, it is advantageous to obtain a strong magnetic field by reducing the inner diameter of the encoder 7 by making the inner diameter of the encoder 7 smaller.

  On the other hand, the magnetic detection element 6 is fixed to the housing 2 side. The rotation sensor unit includes a sensor case 25 having a recess 24 that is open toward the encoder 7. The magnetic detection element 6 is soldered to the circuit board 26, and the circuit board 26 is fixed inside the recess 24.

  The conversion circuit portion 21 of the magnetic detection element 6 fixed to the sensor case 25 is covered from the housing 2 side by the recess 24. That is, the side peripheral wall 24a that forms the recess 24 covers the conversion circuit unit 21 from both the axial direction and the circumferential direction, and the bottom wall 24b that forms the recess 24 covers the conversion circuit unit 21 from the radial direction. Since the wall portions 24 a and 24 b forming the concave portions 24 are made of a magnetic material, they serve as magnetic shields that prevent the external magnetic field from reaching the conversion circuit portion 21 from within the cross section of the housing 2. A hole 28 for guiding the wiring 27 connected to the circuit board 26 to the outside of the recess 24 is opened at a position where the conversion circuit portion 21 is not hindered by the recess 24. Such a sensor case 25 can be formed of a plate material, for example, a steel plate.

  By putting resin in the recess 24 and burying the magnetic detection element 6 and the circuit board 26 in the resin, the magnetic detection element 6 can be prevented from being damaged by vibration and water immersion. By this resin sealing, the circuit board 26 can be fixed to the concave portion 24, and also necessary line connection terminal portions such as required electronic components and wiring 27 attached to the circuit board 26 can be filled.

  The housing 2 has a case accommodating port 29 in a region larger in diameter than the inner diameter surface 8 that forms the bearing seats of the first bearing 4 and the second bearing 5. In order to form the housing 2 into a male mold and a female mold that are separated in the axial direction, the case receiving port 29 is opened in the axial direction and is recessed from the inner diameter surface 8. The sensor case 25 to which the magnetic detection element 6 or the like is fixed can be inserted inside the case accommodation port 29. At this time, the wiring 27 coming out of the recess 24 can be taken out through the through hole 30 of the housing 2. The case receiving port 29 is fitted with the outer surface of the recessed portion 24 inserted therein and determines the position of the sensor case 25. Thereafter, the sensor case 25 is screwed to the housing 2 by a screw member 31. The wiring 27 that has come out of the housing 2 from the through hole 30 is fixed to the housing 2 with a stopper 32 and a screw member 33. By completely filling the through hole 30 with a resin sealant, it is possible to prevent intrusion of water, muddy water, dust, and the like from the outside.

  In a state where the sensor case 25 is fixed to the case receiving port 29 as described above, there is no portion protruding in the radial direction from the inner diameter surface 8 of the housing 2, and a unit in which the second bearing 5 and the encoder 7 are attached to the shaft body 1 is provided. The housing 2 can be inserted in the axial direction from one of the built-in ports in the axial direction, and can be fitted to the inner diameter surface 8 until the outer ring 13 of the second bearing 5 hits the shoulder 9. The first bearing 4 may be included in the unit, or may be fitted between the shaft body 1 and the inner diameter surface 8 after the unit is inserted. Since the first bearing 4 and the second bearing 5 each have the outer ring 13, a radial gap between the magnetic detection element 6 and the encoder 7 can be secured between the outer rings 13 and 13. The magnetic field emitted from the encoder 7 can be applied to the conversion circuit unit 21 through the axial gap between the outer rings 13 and 13 and the open surface of the recess 24.

  After the unit is inserted and the first bearing 4 and the second bearing 5 are assembled between the shaft body 1 and the inner diameter surface 8, the lid 3 can be attached to the housing 2 from one axial direction. In this attachment, when the inner diameter surface 20 of the lid 3 is fitted to the outer diameter surface of the outer ring 13 of the first bearing 4, the outer ring is fitted by fitting between the inner diameter surface 8 of the housing 2 and the outer diameter surface end of the outer ring 13. 13 and the inner diameter surface 8 are coaxial. For this reason, the center positioning of the inner diameter surface 20 of the lid 3 and the inner diameter surface 8 of the housing 2 is performed, and misalignment does not occur. By pressing the outer ring 13 in the axial direction with the lid 3 to be attached, preload may be applied to the first bearing 4 and the second bearing 5 to increase the rotational accuracy of the shaft body 1.

  When the lid 3 is attached, the axial positions of the first bearing 4 and the second bearing 5 are determined by the lid 3, the spacer portion 22, and the shoulder 9, and the shaft body 1 is connected to the inner diameter surface of the housing 2 by these bearings 4 and 5. 8 and the inner diameter surface 20 of the lid 3 are supported in the radial direction. Further, since the assembly port, the case housing port 29 and the sensor case 25 formed on the inner diameter surface 8 of the housing 2 are covered from one side in the axial direction by the lid 3, the inner space of the housing 2, the inner space by the shaft body 1 and the lid 3. Is formed. The internal space is prevented from entering water, muddy water, dust, and the like from the outside by sealing the oil seal 10 and the O-ring 19.

  When the first bearing 4 and the second bearing 5 support the shaft body 1 in the axial direction, the spacer portion 22 resists the axial load applied to both the bearings 4 and 5, and the axial direction between the inner rings 12 and 12. Keep the interval. For this reason, the bearing distance between both the bearings 4 and 5 is maintained. Therefore, the encoder 7 disposed between the bearings 4 and 5 is not compressed by the first bearing 4 and the second bearing 5.

  The entire shaft body 1 including the spacer portion 22 is formed of a magnetic material. Further, the entire inner rings 12, the entire outer rings 13, and the entire rolling elements 14 in the first bearing 4 and the second bearing 5 are also formed of a magnetic material. Therefore, the shaft body 1, the inner rings 12, the outer rings 13, and the rolling elements 14 serve as magnetic shields that cover the conversion circuit unit 21 from the shaft body 1 side. The shaft body 1 serves as a magnetic shield that covers the encoder 7 from the radial direction. Moreover, each inner ring | wheel 12, each outer ring | wheel 13, and each rolling element 14 become a magnetic shield which covers the encoder 7 from both radial direction and an axial direction. When there is anxiety about the magnetic shield due to the revolution of each rolling element 14, the core metal of the seal 15 is formed of a magnetic material, and the inner ring 12 and the outer ring 13 are covered with the core metal from the axial direction, or the rolling element 14 is A cage that is equally distributed in the direction may be formed of a magnetic material.

  Since there is a magnetic shield by the recess 24, the housing 2 and the lid 3 can be formed of a nonmagnetic material such as resin or aluminum. Forming the housing 2 and the lid 3 with a non-magnetic material lighter than iron such as resin and aluminum can reduce the weight of the housing 2 and the lid 3 than when forming the housing 2 and the lid 3 with a ferrous material such as a cold rolled steel plate or a general structural rolled steel. Can be planned. Moreover, the axial length of the rotation sensor unit on the extension of the shaft body 1 can be shortened by forming the lid 3 thin.

  As described above, in this rotation sensor unit, the encoder 7 is disposed between the first bearing 4 and the second bearing 5, and the magnetic detection element 6 is disposed at a position facing the encoder in the radial direction. Between the magnetic detection element 6 and the encoder 7, and a gap for making these opposite to each other are not necessary. The size of the extra axial space that is no longer necessary corresponds to the size of the radial distance L 1 between the outer diameter surface of the encoder 7 and the back plate surface of the circuit board 26. The inter-bearing distance L2 between the first bearing 4 and the second bearing 5 is expanded without increasing the total axial length of the rotation sensor unit by utilizing the surplus axial space for L1. As a result, the rotation sensor unit has an improved moment load support capability by the bearings 4 and 5, so that the radial load F allowed at the other axial end of the shaft body 1 can be increased. .

  The technical scope of the present invention is not limited to the above-described embodiment, but includes all modifications within the scope of the technical idea based on the description of the scope of claims. For example, as shown in FIG. 2, the magnetic detection element 6 may be arranged in a combination different from that in FIG. The rotation sensor unit according to the present invention can be incorporated into other devices such as industrial machines, office machines, transporters, construction machines, rail cars, automobiles, and motorcycles.

DESCRIPTION OF SYMBOLS 1 Shaft body 2 Housing 3 Lid 4 1st rolling bearing 5 2nd rolling bearing 6 Magnetic detection element 7 Encoder 8, 20 Inner surface 12 Inner ring 13 Outer ring 14 Rolling body 16 Center part 17 Outer part 21 Magnetic-electric conversion circuit part 22 Spacer Part 24 concave part 24a side peripheral wall 24b bottom wall 25 sensor case 26 circuit board 29 case accommodation port

Claims (6)

A shaft body (1), a housing (2), a lid (3) covering one of the axially assembling ports of the housing (2), a first rolling bearing (4), and a second rolling bearing (5); A magnetic detection element (6) for detecting a change in the magnetic field, and an encoder (7) that rotates integrally with the shaft body (1) and converts the rotation into the change in the magnetic field,
The first rolling bearing (4) and the second rolling bearing (5) supporting the shaft body (1), the magnetic detection element (6), and the encoder (7) include the housing (2). A rotation sensor unit disposed in an inner space formed in an inner space formed between the shaft (1) and the lid (3),
The encoder (7) is disposed between the first rolling bearing (4) and the second rolling bearing (5), and the magnetic detection element (6) is relative to the encoder (7) in the radial direction. It is arranged at the position to
A sensor case (25) having a wall made of a magnetic material covering the magnetic-electric conversion circuit part (21) included in the magnetic detection element (6) from the housing (2) side;
The shaft body (1), the race rings (12, 13) and rolling elements (14) of the first rolling bearing (4), and the race rings (12, 13) and rolling elements of the second rolling bearing (5). (14) A rotation sensor unit, wherein the rotation sensor unit is made of a magnetic material . The sensor case (25) has a recess (24) that is open toward the encoder (7) ;
The recess formed in the magnetic material (24) is, the magnetic detection element (6) contains magnetic - rotation according to electrical conversion circuit unit cormorants covering (21) from the housing (2) side 請 Motomeko 1 Sensor unit.   The rotation sensor unit according to claim 2, wherein the lid (3) is made of a nonmagnetic material.   The encoder (7) made of an annular magnet is fixed between an inner ring (12) of the first rolling bearing (4) and an inner ring (12) of the second rolling bearing (5). 4. The rotation sensor unit according to any one of 3 above. The shaft body (1) has a spacer portion (22) that maintains an axial interval between the inner ring (12) of the first rolling bearing (4) and the inner ring (12) of the second rolling bearing (5). Have
The rotation sensor unit according to claim 4, wherein the encoder (7) is supported in the radial direction by the spacer portion (22).   A bearing seat for fitting the outer ring (13) of the first rolling bearing (4) includes an inner diameter surface (20) formed on the lid (3) and an inner diameter surface (8) formed on the housing (2). The rotation sensor unit according to claim 1, comprising:

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