JP2008241557A - Rotation detecting sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detecting sensor having excellent seal performance, preventing invasion of water from the outside, without the occurrence of damages to sensor parts or circumferential circuits by internal heating distortion, due to internal heating and the temperature change of external environment, and external force, which can be manufactured at low cost. <P>SOLUTION: This rotation detecting sensor A is fixed at a sensor fixing member 7, attached to a wheel bearing to detect the rotation of the rotating wheel of the wheel bearing. A sensor unit B comprises a magnetic sensor element 1 for detecting the detecting object of the rotating wheel; a cable 10 for extracting the output signal of the sensor element 1 to the outside; and a board 11, where the sensor element 1 and one end part of the cable 10 are attached, having a conductive part 3 which connects the electrode part 2 of the sensor element 1 to the core wire 4 of the cable 10. This sensor unit B is fixed to the sensor fixing member 7 through the board 11. A molding part 8, formed of thermoplastic elastomer or rubber material, is set in the surrounding of the sensor unit B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotation detection sensor used as, for example, an automobile ABS sensor.

  The ABS sensor (axle rotation sensor) used by mounting on a hub bearing of an automobile is provided with a magnet or a metal body on the rotating ring of the hub bearing, and a magnetic sensor such as a magnetic pickup, a hall sensor, or an MR sensor is arranged opposite to the magnet. The configuration is ABS sensors are required to have mechanical strength, waterproofness, weather resistance, chemical resistance, and the like. Therefore, it is used as a sensor unit structure by overmolding the sensor component with resin or the like.

As a method for overmolding a sensor component, for example, Patent Document 1 proposes a method in which a sensor component is fixed in advance to a sensor fixing holder and is overmolded with a resin.
JP 2000-88984 A

The sensor unit structure for an ABS sensor by the conventional overmolding method has the following problems.
-Since the molding material is a resin, it is not possible to expect adhesion between the built-in product such as a sensor component or a sensor fixing holder and the molding material.
-Due to the self-heating of sensor parts, which are electronic parts, and changes in the environmental temperature, there is a risk of a gap between the built-in product and the mold material, resulting in a problem with waterproofness.
-Even when an external force is applied to the sensor unit structure and plastic deformation occurs in the molding material, there is a problem in waterproofness because a gap is formed between the built-in product and the molding material.
-Since the molding material made of resin has a low deformation capacity, when an external force is applied to the sensor unit structure, the built-in product may be damaged or deformed by the external force acting directly on the built-in product.
・ Since the mold material made of resin has poor vibration absorption, there is a problem in durability against external vibration.
-If an external force is applied that causes the signal cable section that is a signal transmission path from the sensor unit structure to the outside to bend, the external force may be transmitted to the sensor device inside the sensor unit structure, resulting in failure.
A conventional mold by injection molding requires a nozzle that allows molten resin to flow in, a runner that guides the molten resin to a hollow portion that becomes a molded product, and an inlet (gate) to the hollow portion. In order to increase the yield by smoothing the flow of the molten resin passing through these, the number of manufactured parts at one time is appropriate from several to about ten, and the number of molded parts at one time is limited.

  The object of the present invention is excellent in sealing performance to prevent the ingress of water from the outside, the internal heat distortion due to internal heat generation and the temperature change of the external environment, and the external force do not cause damage to the sensor component and its peripheral circuit part. It is to provide a rotation detection sensor that can be manufactured at low cost.

  A rotation detection sensor according to the present invention is a rotation detection sensor that is fixed to a sensor fixing member that is attached to a wheel bearing and detects the rotation of a rotating wheel of the wheel bearing, and is an annular cover that is provided concentrically with the rotating wheel. A magnetic sensor element for detecting the detection body, a cable for taking out an output signal of the sensor element to the outside, the sensor element and one end of the cable are attached, and the electrode part of the sensor element and the core wire of the cable The sensor unit is composed of a substrate having a conductive portion that is electrically connected to the sensor unit, the sensor unit is fixed to the sensor fixing member by the substrate, and a thermoplastic elastomer or a rubber material is molded around the sensor unit. It is characterized by providing a molding part.

According to the configuration of the present invention, the following effects can be obtained.
・ Since the sensor unit consisting of sensor parts such as sensor elements, cables, and substrates is molded with a mold material made of elastic thermoplastic elastomer or rubber material, when vibration or external force is applied to the rotation detection sensor, Since the external force is absorbed by the molding material, the influence on the sensor component can be reduced and the sensor component can be protected.
・ Since the molding material is an elastic thermoplastic elastomer or rubber material, thermal expansion / contraction of the sensor component and the molding material differed due to changes in environmental temperature and self-heating of the sensor component, which is an electronic component. Even in such a case, the difference can be absorbed by the elasticity of the molding material, so that a gap is not generated between the sensor component and the molding material, and waterproofness can be maintained.
-In particular, when the molding material is a rubber material, the adhesion between the molding material and the metal of the sensor component is good, and waterproofness can be ensured.

The molding can be performed using a mold. In that case, the mold is composed of an upper mold and a lower mold, and the sensor unit and a thermoplastic elastomer or rubber material are placed between the upper mold and the lower mold, and the upper mold and the lower mold are heated while both molds are in between. The molding part may be molded by applying pressure.
If molding of the molding part is compression molding using a mold, a large number of rotation detection sensors can be manufactured by one molding, and the cost can be reduced. If the mold is composed of an upper mold and a lower mold, the sensor unit can be easily positioned and an appropriate pressure can be applied to the thermoplastic elastomer or rubber material.

  As the sensor element, a Hall element, a magnetoresistive effect element (MR element), a giant magnetoresistive effect element (GMR element), a tunnel magnetoresistive element (TMR element), or a coil can be used. Whichever is used, a good rotation detection sensor is obtained.

The sensor fixing member may be attached to a fixed wheel of a wheel bearing or a peripheral member thereof.
When the sensor fixing member is attached to the fixed wheel of the wheel bearing or its peripheral member, it is not necessary to provide another member for attaching the rotation detection sensor, and the configuration is simplified.

The sensor fixing member may also serve as a wheel bearing cover.
Also in this case, it is not necessary to provide a separate member for attaching the rotation detection sensor, and the configuration is simplified.

  A rotation detection sensor according to the present invention is a rotation detection sensor that is fixed to a sensor fixing member that is attached to a wheel bearing and detects the rotation of a rotating wheel of the wheel bearing, and is an annular cover that is provided concentrically with the rotating wheel. A magnetic sensor element for detecting the detection body, a cable for taking out an output signal of the sensor element to the outside, the sensor element and one end of the cable are attached, and the electrode part of the sensor element and the core wire of the cable The sensor unit is composed of a substrate having a conductive portion that is electrically connected to the sensor unit, the sensor unit is fixed to the sensor fixing member by the substrate, and a thermoplastic elastomer or a rubber material is molded around the sensor unit. Because of the molding part, it has excellent sealing performance to prevent the ingress of water from the outside, internal heat generation and internal temperature change due to external environment temperature change Thermal distortion or damage does not occur in the sensor part and a peripheral circuit portion by an external force. Further, since the molding of the molding part is compression molding using a mold, a large number of rotation detection sensors can be manufactured by one molding, and the cost can be reduced.

  An embodiment of the present invention will be described with reference to FIGS. In the rotation detection sensor A, a sensor unit B composed of a plurality of sensor components is fixed to a sensor fixing member 7, and the molding unit 8 is provided by molding the periphery of the sensor unit B. This rotation detection sensor A is used in combination with an object to be detected such as a magnetic encoder 45.

  The sensor unit B includes a magnetic sensor element 1, a cable 10 for taking out an output signal of the sensor element 1, and a substrate 11 to which the sensor element 1 and one end of the cable 10 are attached. The sensor element 1 is, for example, a Hall element, a magnetoresistive effect element (MR element), a giant magnetoresistive effect element (GMR element), a tunnel magnetoresistive element (TMR element), a coil, or another magnetic sensor element. Consists of. In the case of this embodiment, the cable 10 has two cable core wires 4. Each cable core wire 4 is covered with an insulating coating 5 in an electrically insulated state, and each insulating coating 5 is covered with a cable cover 6. It is supposed to be.

  The electrode part 2 of the sensor element 1 is electrically connected to the conductive part 3 of the substrate 11, and the cable core wire 4 of the cable 10 is electrically connected to the conductive part 3. The conductive part 3 is made of a metal having good electrical conductivity such as copper foil. That is, the electrode part 2 of the sensor element 1 and the core wire 4 of the cable 10 are electrically connected via the conductive part 3. The conductive portion 3 is attached to the front surface side (FIG. 3A) of the substrate 11, and the sensor element 1 is attached to the back surface side (FIG. 3B) of the substrate 11. 2 extends from the back side to the front side of the substrate 11 through the outside of the substrate 11. The electrode part 2 and the conductive part 3 are electrically connected by pressure bonding, soldering, thermocompression bonding, or other joining methods. The cable core 4 and the conductive portion 3 are electrically connected by crimping, soldering, or other joining methods.

  The sensor fixing member 7 also serves as a cover for covering the end face of the wheel bearing (see FIG. 11), and is a metal product formed by sheet metal processing, for example. The sensor fixing member 7 includes a stepped annular portion 7a having a large diameter portion 7aa and a small diameter portion 7ab, and a flange portion 7b extending from the edge of the small diameter portion 7ab of the annular portion 7a toward the inner diameter side. As shown in FIG. 2, the sensor unit B is fixed to the sensor fixing member 7 by fixing the substrate 11 to the flange portion 7 b of the sensor fixing member 7 with the fixture 12. An opening 7 c is formed in the flange portion 7 b, and the sensor element 1 protrudes through the opening 7 c to the side opposite to the fixed surface of the substrate 11. Various fixtures such as pins, screws, and rivets can be used as the fixture 12.

  As shown in FIGS. 1 (A) and 1 (C), a part of the sensor fixing member 7 is provided with a clamp portion 9 for winding and fixing a portion near the end of the cable 10 on the sensor unit B side. Yes. In this embodiment, the clamp portion 9 is integrated with the sensor fixing member 7, but may be a separate member.

  The sensor unit B is molded by compressing a molding material. The molding material is made of a material having rubber elasticity, and a rubber material or a thermoplastic elastomer can be used. As the rubber material, nitrile rubber or fluororubber is desirable. These are excellent in heat resistance, low temperature characteristics, and oil resistance. Rubber materials other than the above may be used. As the thermoplastic elastomer, vinyl chloride, ester and amide are desirable. These are excellent in heat resistance and oil resistance.

  The compression molding of the molding material is preferably compression molding using a mold. For example, as shown in FIG. 4A, the compression molding by the mold is performed by inserting the sensor unit B, the sensor fixing member 7 and the molding material 22 between the upper mold 20 and the lower mold 21 which are molds. ), The upper mold 20 and the lower mold 21 are heated and pressure is applied between the two molds. Since the substrate 11 is fixed to the sensor fixing member 7, the position of the sensor unit B does not move due to the internal pressure in the molds 20 and 21 during compression molding, and the sensor unit B can be easily positioned. Further, when the mold is composed of the upper mold 20 and the lower mold 21, the positioning of the sensor unit B is easy, and an appropriate pressure can be applied to the thermoplastic elastomer or the rubber material. Furthermore, if molding of the molding part 8 is compression molding using a mold, a large amount of rotation detection sensor A can be manufactured by one molding, and the cost can be reduced.

In the rotation detection sensor A having the above-described configuration, since the sensor unit B is molded with a mold material made of an elastic thermoplastic elastomer or rubber material, when vibration or external force is applied to the rotation detection sensor A, the vibration or external force is molded. The absorption by the part 8 can reduce the influence on each sensor component of the sensor unit B and protect the sensor component. In addition, since the molding part 8 is made of an elastic thermoplastic elastomer or rubber material, the thermal expansion / shrinkage of the sensor component and the molding part 8 differ in degree due to changes in environmental temperature and self-heating of the sensor component which is an electronic component. Even if this occurs, the difference can be absorbed by the elasticity of the molding part 8, preventing a gap from being formed between the sensor component and the molding part 8, and maintaining waterproofness. In particular, when the molding material is a rubber material, the adhesiveness between the molding part 8 and the metal of the sensor component is good, and waterproofness can be ensured.
Since the sensor fixing member 7 also serves as a wheel bearing cover, the rotation detection sensor A can be easily positioned and the number of components can be reduced. Further, since the sensor fixing member 7 is made of metal, when the molding material is a rubber material, the adhesion between the sensor fixing member 7 and the molding portion 8 is good, and the rotation detection sensor A as a whole has a strong structure. Can do.
Since the portion near the end on the sensor unit B side of the cable 10 is fixed to the sensor fixing member 7 by the clamp portion 9, even when an external force is applied to the cable 10, the clamp portion 9 receives a load and the sensor unit B and molding part 8 are not loaded.

  5 to 9 show different electrical connection methods between the electrode portion 2 of the sensor element 1 and the cable core wire 4. FIG. 5 shows that the two cable core wires 4 are connected to the conductive portion 3 at the same position in the line direction of the cable core wire 4 by deforming the shape of the conductive portion 3 with respect to the embodiment of FIGS. It is made to be done. 6 and 7 both have the sensor element 1 and the conductive portion 3 provided on the same surface of the substrate 11. In FIG. 8, the sensor element 1 is directly connected to the conductive part 3 without providing the electrode part in the sensor element 1. 9 shows that when the sensor element 1 and the conductive portion 3 are provided on different surfaces of the substrate 11, a through hole 11a is provided in the substrate 11, and the electrode portion 2 of the sensor element 1 is passed through the through hole 11a. It is provided. The electrode portion 2 of the sensor element 1 and the cable core wire 4 may be electrically connected by any of the methods shown in FIGS. 3 and 5 to 9, and an appropriate method may be selected according to various conditions.

  FIG. 10 shows different fixing methods of the substrate 11 to the sensor fixing member 7. In this fixing method, protrusions 25 and 26 are provided on the sensor fixing member 7, and the substrate 11 is sandwiched and positioned and fixed between the protrusions 25 and 26 and the main body of the sensor fixing member 7. According to this fixing method, the fixing tool 12 becomes unnecessary, the number of parts can be reduced, and the trouble of mounting the fixing tool 11 can be saved.

  FIG. 11 shows a wheel bearing device provided with the rotation detection sensor of the present invention. This wheel bearing device has a rotation detection sensor A attached to a bearing portion 30. In the following description, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.

  The bearing portion 30 includes an outer member 31 in which a double row rolling surface 33 is formed on the inner periphery, an inner member 32 in which a rolling surface 34 that faces each of the rolling surfaces 33 is formed, and these outer members. 31 and a double row rolling element 35 interposed between the rolling surfaces 33 and 34 of the inner member 32. The rolling elements 35 in each row are held by a holder 36. Both ends of the bearing space between the outer member 31 and the inner member 32 are sealed by sealing devices 37 and 38, respectively.

  The outer member 31 is a fixed wheel, is an integral part, and is provided with a flange 31a on the outer periphery for attachment to a knuckle (not shown) extending from the suspension device of the vehicle body. The inner member 32 is a rotating wheel, and includes a hub wheel 39 having a wheel mounting flange 39a on the outboard side, and an inner ring 40 fitted to the outer periphery of the inboard side end of the hub wheel 39. Become. The hub ring 39 and the inner ring 40 are formed with the rolling surfaces 34 of the respective rows. The inner member 32 has an axial through hole 41 at the center, and a stem portion (not shown) of one joint member of the constant velocity joint is inserted into the through hole 41.

  In the sealing device 38 on the inboard side of the sealing devices 37 and 38, a magnetic encoder 45 as a detection object is incorporated. The magnetic encoder 45 is provided with a multipolar magnet 45b on a side plate portion of a ring member 45a having an L-shaped cross section. The ring member 45a includes a cylindrical portion that is attached to the outer periphery of the inner member 2 by press fitting, and the side plate portion that extends from the inboard side end of the cylindrical portion to the outer diameter side. The multipolar magnet 45b is a member formed with alternating magnetic poles N and S in the circumferential direction, and is made of a rubber magnet, a plastic magnet, a sintered magnet, or the like. In this embodiment, the magnetic encoder 45 also serves as a component of the inboard side sealing device 38 and functions as a slinger.

The sensor fixing member 7 is configured such that the annular portion large diameter portion 7aa is fitted to the outer peripheral surface inboard side of the outer member 1, and the step surface of the annular portion large diameter portion 7aa and the small diameter portion 7ab is disposed on the outer member. 1 is attached to the outer member 1 in contact with the end face on the inboard side. The sensor fixing member 7 also serves as a cover for the end face on the inboard side of the wheel bearing. In a state where the sensor fixing member 7 is attached, the rotation detection sensor A is positioned facing the magnetic encoder 45.
When the inner member 1 that is a rotating wheel rotates, the sensor element 1 detects the magnetic poles N and S of the magnetic encoder 45 that rotates together with the inner member 1. The detection signal is transmitted to the automobile electric control unit (not shown) via the cable 10, and the rotation speed is calculated from the detection signal of the sensor element 1 by the electric control unit.

The rotation detection sensor of this embodiment is of a type that faces the magnetic encoder in the axial direction, but the present invention can also be applied to a type that faces the magnetic encoder in the radial direction. As an object to be detected, a pulse coder may be used instead of the magnetic encoder.
Further, a magnetic encoder or pulse coder as a detected object may be attached to a wheel for an automobile.
Furthermore, in this embodiment, the sensor fixing member 7 is directly attached to the fixed wheel, but may be attached to the fixed wheel via another member.

(A) Front view of rotation detection sensor according to embodiment of the present invention, (B) is an IB-IB sectional view, and (C) is an IC-O sectional view. It is the II section enlarged view of FIG. 1 (A). (A) is a front view of the connection part of a sensor element, a cable, and a board | substrate, (B) is the back view. It is explanatory drawing which shows the method of compression molding. It is a front view of the connection part of a different sensor element, a cable, and a board | substrate. Furthermore, it is a front view of the connection part of a different sensor element, a cable, and a board | substrate. Furthermore, it is a front view of the connection part of a different sensor element, a cable, and a board | substrate. Furthermore, it is a front view of the connection part of a different sensor element, a cable, and a board | substrate. (A) is a front view of the connection part of a further different sensor element, cable, and board | substrate, (B) is the back view. (A) is a partial enlarged front view of the rotation detection sensor in which the method of fixing the substrate to the sensor fixing member is different, and (B) is an XB-XB sectional view. It is sectional drawing of the wheel bearing apparatus which provided the rotation detection sensor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sensor element 2 ... Electrode part 3 ... Conductive part 4 ... Cable core wire 7 ... Sensor fixing member 8 ... Molding part 9 ... Clamp part 10 ... Cable 11 ... Board | substrate 20 ... Upper mold (metal mold | die)
21 ... Lower mold (mold)
22 ... Mold material 45 ... Magnetic encoder (detected body)
A ... Rotation detection sensor B ... Sensor unit

Claims (6)

  A rotation detection sensor which is fixed to a sensor fixing member attached to a wheel bearing and detects the rotation of a rotating wheel of the wheel bearing, and is a magnetic sensor which detects an annular detection object provided concentrically with the rotating wheel. A sensor element, a cable for taking out an output signal of the sensor element to the outside, a conductive element for attaching the sensor element and one end of the cable, and electrically connecting the electrode part of the sensor element and the core wire of the cable A sensor unit is configured with a substrate having a portion, the sensor unit is fixed to the sensor fixing member with the substrate, and a molding portion formed by molding a thermoplastic elastomer or a rubber material is provided around the sensor unit. A rotation detection sensor characterized by that.   The rotation detection sensor according to claim 1, wherein the molding is molding using a mold.   3. The mold according to claim 2, wherein the mold includes an upper mold and a lower mold, the sensor unit and a thermoplastic elastomer or rubber material are placed between the upper mold and the lower mold, and both molds are heated while heating the upper mold and the lower mold. The rotation detection sensor which shape | molds the said molding part by applying a pressure in between.   4. The rotation detection sensor according to claim 1, wherein the sensor element is a Hall element, a magnetoresistive effect element, a giant magnetoresistive effect element, a tunnel magnetoresistive element, or a coil.   5. The rotation detection sensor according to claim 1, wherein the sensor fixing member is attached to a fixed wheel of a wheel bearing or a peripheral member thereof.   6. The rotation detection sensor according to claim 1, wherein the sensor fixing member also serves as a cover that covers an end surface of the wheel bearing.

Images