JP2006258565A - Hub unit with displacement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hub unit with a displacement sensor capable of detecting highly accurately a load in the axle axial direction. <P>SOLUTION: In this hub 4, a detection part 4a is formed on the end face on the car body inner side in the axial direction, and a sensor cover 70 for covering a displacement detection part in the state where a space is formed in the axial direction between itself and the displacement detection part is provided on the car body inner side rear end of a non-rotating outer ring 5b. The sensor cover 70 is provided with the displacement detection part 71 on a position facing to the detection part 4a inside the sensor cover 70. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a hub unit with a displacement sensor.

JP 2004-270844 A Japanese Patent Laid-Open No. 2004-360782 JP 2004-155261 A

  Various sensors are used for driving control of automobiles. For example, a road surface friction coefficient, a road surface reaction force, a yaw rate, or the like is detected by a load sensor attached to a suspension mechanism that suspends a tire, and the detection output is, for example, It is used to control anti-lock brake systems and steering systems. However, there are some cases where the load detection via the suspension mechanism is not always satisfactory in accuracy. Therefore, as in Patent Document 1 to Patent Document 3, a load sensor is incorporated in the bearing hub unit to which the tire wheel is attached to detect the load with higher accuracy. Proposals have been made. Since the load sensor is incorporated in the bearing hub unit in advance, the assembly of the sensor to the automobile becomes easier and contributes to the improvement of productivity.

  In Patent Documents 1 to 3, a plurality of load sensors in contact with the outer ring of the bearing are provided in the radial direction outside the bearing outer ring. In this configuration, load acting in the radial direction on the axle, such as road surface reaction force (perpendicular to the road surface) and tire friction (direction parallel to the road surface), can be detected with high accuracy, but the load in the axial direction of the axle is In addition, there is a problem of lack of accuracy because it is necessary to find the projection component in the axle direction indirectly from the imbalance of the detected loads provided at different positions in the radial direction and to measure it indirectly.

  The subject of this invention is providing the hub unit with a displacement sensor which can detect the load of an axle axial direction with a high precision using a displacement sensor.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the hub unit with a displacement sensor of the present invention is
A hub having a hub main body and a wheel mounting flange provided in a shape protruding radially outward from the outer peripheral surface of the hub main body, to which a tire wheel is mounted on the vehicle body outer side;
An inner ring provided on the hub body so as to be integrally rotatable on the inner side of the vehicle body from the wheel mounting flange,
An outer ring in which the position in the axial direction is non-rotating and fixed relative to the mounting base on the automobile side on the radially outer side of the inner ring;
A plurality of rolling elements disposed between the inner ring and the outer ring;
A detected portion provided on the hub or the axle so as to cause displacement in the axial direction according to the axial load level acting on the axle;
A displacement detection unit that detects a displacement component in the axial direction of the detected unit in a non-contact manner;
Displacement detection information by the displacement detector is output as information on an axial load applied to the axle.

  The hub unit with a displacement sensor according to the present invention includes a detected portion provided on either the axle or the hub so as to cause displacement in the axial direction according to an axial load level acting on the axle, and a detected portion. A displacement detection unit that detects a displacement component in the axial direction in a non-contact manner, and outputs displacement detection information by the displacement detection unit as information on an axial load applied to the axle. As a result, the axial load applied to the axle can be detected with much higher accuracy than a conventional hub unit with a load sensor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional structure of an example of a hub unit 6 with a displacement sensor according to an embodiment of the present invention. The hub unit 6 with a displacement sensor has a cylindrical hub main body 4b attached to the outer peripheral surface of the front end portion of the axle 2, and a wheel mounting portion 4a protruding outward in the radial direction from the outer peripheral surface of the hub main body 4b. 4, an inner ring 5 a provided to be integrally rotatable with the hub body 4 b on the vehicle body inner side of the wheel mounting flange 4 a, and a non-rotating and axial direction with respect to the mounting base 3 on the vehicle side outside the inner ring 5 a in the radial direction. The outer ring 5b is disposed at a fixed position, and a plurality of rolling elements 5c are disposed between the inner ring 5a and the outer ring 5b. A tire wheel 302 and a brake disc 301 are attached to the main body outer side main surface of the wheel attachment flange 4a. Reference numeral 8 denotes a wheel mounting bolt. The hub unit 6 in this figure is used on the side of a driven wheel of an automobile, and the hub body 4b is a solid member and is also used as an axle.

  In the configuration of FIG. 1, the bearing is a double-row outward angular ball bearing, and on the outer periphery of the hub body 4 b, a single-row inner ring 5 a (the other inner ring has the outer peripheral surface of the hub body 4 b as a raceway surface, The outer ring 5b having two rows of raceway grooves, a plurality of balls (rolling elements) 5c arranged in two rows, and two crown-shaped cages 5d and 5d. ing. On the outer peripheral surface of the hub main body 4b, an inner ring restricting portion 4d for restricting the relative movement in the axial direction of the inner ring 5a with respect to itself is formed so as to protrude in the radial direction. The inner ring restricting portion 4d is an inner wall portion of an annular cutout portion formed on the outer peripheral surface of the hub body.

  The hub 4 has a detected portion 4e formed on an end surface (hereinafter also referred to as a rear end surface) on the inner side of the vehicle body in the axial direction, and a displacement detection portion on the rear end portion of the non-rotating outer ring 5b on the inner side of the vehicle body. A sensor cover 70 is provided so as to cover a space in the axial direction. The sensor cover 70 is provided with a displacement detection unit 71 at a position facing the detected portion 4e inside the sensor cover 70. According to the hub unit 6 with a displacement sensor, the axial load applied to the axle can be detected with high accuracy based on the displacement of the hub 4. Further, since the sensor cover 70 is rotated, the output from the displacement detection unit 71 can be easily taken out. In addition, the detection sensitivity is hardly deteriorated due to dirt adhering to the detected portion 4e.

  In the present embodiment, the detected portion 4e is formed in a region including the rotation axis on the end surface on the vehicle body inner side of the driven wheel side axle disposed inside the hub body 4b. By forming the detected part 4e on the rotation axis of the hub 4, the rotational displacement of the detected part 4e is suppressed, and the axial load can be detected with high accuracy. In the present embodiment, the hub body 4b has a solid structure in which an axle is integrated, and the detected portion 4e is formed on the end surface of the solid hub body 4b on the inner side of the vehicle body. . As a result, it is not necessary to assemble the axle to the hub, and the end surface of the hub body 4b on the vehicle body inner side is utilized as the detected portion 4e, thereby further simplifying the displacement detection mechanism.

  In FIG. 1, the sensor cover 70 is provided in a form that fits into an opening on the vehicle body inner side of the outer ring 5b. A rear end portion (or inrow portion) 5m in the axial direction of the outer ring 5b is inserted inside the outer ring accommodation hole 3h of the axle case 3 serving as the outer ring attachment portion. A hub mounting flange 5f is formed on the outer peripheral surface of the outer ring 5b so as to protrude in the radial direction. By bringing the hub mounting flange 5f into contact with the peripheral edge of the outer ring receiving hole 3h of the axle case 3, the axle of the outer ring 5b is contacted. The relative movement in the axial direction with respect to the case 3 is restricted. An outer ring fastening portion 5e is integrated with the hub mounting flange 5f, and a bolt insertion hole 5h is formed therethrough. Then, an outer ring fastening bolt 5v serving as a fastening member is screwed into the axle case 3 through the bolt insertion hole 5h, and the outer ring 5b is attached to the axle case 3.

  In the present embodiment, the displacement detector is configured by the proximity sensor 71. The proximity sensor 71 can measure the axial displacement described above at low cost and with high accuracy. In particular, in the case of an inductive eddy current type proximity sensor, if the displacement detector 4e is formed of metal, even if lubricant droplets or the like from the bearing side adhere, the measurement sensitivity is hardly affected.

  In FIG. 1, the body inner side end surface 4e of the hub body 4b made of solid metal is used as a detected portion, and the displacement is measured by an inductive eddy current type proximity sensor 71. The end portion on the vehicle body inner side of the hub body 4b extends rearward from the inner ring 5a, and an inner ring fixing nut 102 is screwed and fastened to a male screw portion formed on the outer peripheral surface of the extended portion. Yes. Further, the probe center of the proximity sensor 71 is positioned on the rotation axis of the vehicle body inner side end surface (that is, the detected portion) 4e of the hub body 4b.

  FIG. 2 shows an example of the output control circuit of the proximity sensor 71. The proximity sensor 71 includes a probe coil 71a, an oscillation circuit 71b that supplies an alternating current to the probe coil 71a, an oscillation state detection circuit 71c that detects an oscillation state of the probe coil 71a, and a detected part based on the oscillation state waveform. And an output circuit 71d for performing output reflecting the distance. When the probe coil 71a is brought close to the detected part while applying an alternating current, an eddy current is excited in the detected part by the alternating magnetic field from the probe coil 71a. This eddy current generates an alternating magnetic field in a direction that cancels the alternating current of the probe coil 71a according to the distance to the detected part. Therefore, the distance between the probe coil and the detected part can be known from the amplitude of the voltage waveform of the probe coil 71a detected by the oscillation state detection circuit 71c. The output circuit includes, for example, a peak hold circuit of this voltage waveform and a linearization circuit of the hold output, and outputs a voltage signal proportional to the distance to the detection unit, for example. This output is taken out as displacement information of the detected portion and thus information on the axial load applied to the axle via the voltage follower 162 in the subsequent stage.

  The detection output of the axial load can be measured by extracting a relatively long cycle component such as the yaw rate that works for an automobile, for example. The filter can be removed by a low-pass filter 63 (in FIG. 4, configured as a positive feedback secondary active filter including an operational amplifier 63m, peripheral resistors 63c and 63d, and capacitors 63b and 63e).

  As a displacement detection method, various methods can be adopted in addition to using the proximity sensor as described above. FIG. 3 shows an example in which an optical displacement detection method is adopted (a common reference numeral is assigned to a common part with FIG. 1 and a detailed description thereof is omitted). The detected part can be configured as a reflecting member 60 (here, disposed on the rear end face of the hub body 4b), and the displacement detecting part 51 includes a light source 52 that irradiates the reflecting member 60 with measuring light, and reflection of the measuring light. A reflection light detection unit 56 that detects the reflection light from the member 60 can be provided. Displacement detection information is generated based on the reflected light information.

  The displacement of the wheel mounting flange 4a due to the load applied to the axle is very small, in the order of μm, and sometimes in the order of nm. In order to detect this more inexpensively and with high accuracy, the following method is used. It is also possible to adopt. That is, the astigmatism optical system 51p is configured by an astigmatism optical system 51p that is disposed between the reflection member 60 and the light source 52 and that guides the reflected light LM to the reflected light detection unit 56. Displacement detection information is generated based on the shape change of the detected image by the reflected light detection unit 56 of the reflected light LM that has passed. When the point images are combined by the astigmatism optical system 51p, the image is vertically long, circular, depending on the position of the observation surface (that is, the reflection surface formed by the reflection member (detected portion) 60 at the rear end surface of the hub body 4b). It changes with landscape. If this change in the shape of the detected image is detected using, for example, a quadrant photodetector, the displacement in the optical axis direction can be measured, and if the position where the image is circular is used as a reference, the image is The direction of displacement, that is, the axial load can also be identified depending on whether it is vertically long or horizontally long. Furthermore, a very high displacement detection sensitivity up to about 1 nm can be secured.

  FIG. 4 shows an example thereof. The light source 52 is a laser light source, and the astigmatism optical system 51p includes an objective lens 54, a beam splitter 53, and a cylindrical lens 55. The objective lens 54 has a focal length so that the measurement light LP from the light source 52 is focused on a reference position (for example, the position of the reflecting surface of the reflecting member 60 when no axial load is applied). . The beam splitter 53 is disposed on the incident path to the objective lens 54, and separates the reflected light LM from the reflecting member 60 in a direction perpendicular to the incident optical axis of the measuring light LP. The reflected light LM is received by the reflected light detection unit 56.

  The cylindrical lens 55 is provided on the incident path of the reflected light LM to the reflected light detection unit 56 and has astigmatism. The light beam that passes through the cylindrical lens 55 and converges toward the reflecting member 60 has a circular cross section when the reflected light detection unit 56 is located at a neutral position J, and the position of the reflected light detection unit 56 is on the light beam. If it moves relative to the position N side close to the cylindrical lens 55, it becomes longer in the vertical direction (cylindrical axis direction of the cylindrical lens 55), and conversely if it moves relatively far to the position F side, it moves in the horizontal direction (direction perpendicular to the cylindrical axis of the cylindrical lens 55). It becomes long. The arrangement position is determined so that the reflected light detection unit 56 becomes the neutral state position J in a state where the reflection member 60 is located at the focal position of the lens 54 (corresponding to the state where no axial load is added). Thereby, when the reflecting member 60 is closer than the reference position, that is, when an axial load is acting in the positive direction of FIG. 3, the image on the reflected light detection unit 56 becomes a horizontally long ellipse, and the reflecting member 60 is When far from the reference position, that is, when an axial load is acting in the negative direction of FIG. 1, the image on the reflected light detection unit 56 becomes a vertically long ellipse.

  The above-described image shape can be identified by configuring the reflected light detection unit 56 as a four-divided photodetector as follows. The detector is composed of sensor pairs A and C (for detecting in the horizontal direction) and sensor pairs D and B (for detecting in the vertical direction) facing each other along the two elliptical axes of the expanding and contracting image. In this case (positive load), the amount of light received by the pair of vertical detection sensors D and B increases, and the amount of light received by the pair of horizontal detection sensors A and C decreases. Conversely, when the shape is horizontally long (reverse load), the amount of light received by the pair of vertical detection sensors D and B decreases, and the amount of light received by the pair of horizontal detection sensors A and C increases. In the neutral state, the received light amounts of both sensor pairs A, C and D, B are equal.

  FIG. 5 is a configuration example of a circuit that generates an axial load detection output from the output from the reflected light detection unit 56. The outputs of the sensor pair A, C (for horizontal direction detection) and the sensor pair D, B (for vertical direction detection) are respectively an adder 59 (comprising an operational amplifier 59m and peripheral resistors 59a to 59c) and an adder 61 (operational amplifier). 61m and peripheral resistors 61a to 61c), and the respective sum outputs are input to the differential amplifier 62 (comprising the operational amplifier 62m and the peripheral resistors 62a to 62d). It is output in the form of a difference ((A + C)-(D + B)) from the input sum of the pairs D and B. This output voltage increases in the positive direction when the axial load increases in the positive direction, and increases in the negative direction when the axial load increases in the negative direction. Therefore, know the direction and value of the axial load from the sign and magnitude of the output voltage. Can do.

  Next, it is possible to configure the detected portion as a ferromagnetic detected portion, and the displacement detecting portion as a magnetic sensor for detecting a magnetic field change resulting from the axial displacement of the ferromagnetic detected portion. In this case, displacement detection information is generated based on the detected magnetic field of the magnetic sensor. According to this method, the distance between the ferromagnetic substance detection portion and the magnetic sensor must be made much closer than in the optical case, but there is an advantage that the sensor sensitivity is less lowered due to dirt or the like.

  FIG. 6 shows an embodiment in this case (the same parts as in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted). A ferromagnetic detection portion 62 made of a permanent magnet is attached to the rear end surface of the hub body 4b. The sensor cover 70 is provided with a magnetic sensor 61 at a position facing the ferromagnetic detected portion 62. The magnetic sensor 61 has a known configuration such as a magnetic head, a Hall element, or a pickup coil, and changes the output voltage (or output current) in accordance with the magnetic field generated by the ferromagnetic detection unit 62. Therefore, the output of the magnetic sensor 61 can know the displacement of the hub body 4b, and hence the generation level of the axial load. The ferromagnetic detection part 62 is formed as a concave / convex part made of a soft magnetic material, and a magnet for generating a bias magnetic field is opposed to the ferromagnetic target part via the magnetic gap so that the ferromagnetic target corresponding to the change in the magnetic gap length due to the concave / convex part is obtained. A method of detecting the magnetization change of the detection unit 62 with a pickup coil provided in the gap is also possible.

  Next, in the hub unit of the present invention, the arrangement positions of the detected part and the displacement detection part are not limited to the above-described aspects, and the application target is not limited to the driven wheel side. FIG. 7 shows an example in which the present invention is applied to a hub unit on the drive wheel side. In the hub unit 106, a detected portion 60 is provided on the main surface of the wheel mounting flange 4a on the inner side of the vehicle body, and a displacement component in the axial direction of the detected portion 60 is detected by the displacement detecting portion 51 in a non-contact manner. The Displacement detection information by the displacement detector 51 is output as information on the axial load applied to the axle 2. According to the hub unit 106 with the displacement sensor, the axial load applied to the axle can be detected with high accuracy based on the displacement of the hub 4 provided integrally with the axle 2. In FIG. 7, an optical displacement detection unit 51 exactly the same as in FIG. 1 is used.

  In the configuration of FIG. 7, the axle front end 2t has a diameter smaller than that of the axle main body 2m adjacent to the rear end, and the hub main body 4b is extrapolated to the axle front 2t. At the boundary position between the axle tip 2t and the axle body 2m, a step 2f is formed that contacts the rear end surface of the hub body 4b. The bearing is composed of a double-row outward angular ball bearing, and has two single-row inner rings 5a that are press-fitted and fitted on the outer periphery of the hub body 4b so as to be adjacent to each other in the axial direction. Outer ring 5b, a plurality of balls (rolling elements) 5c arranged in two rows, and two crown-shaped cages 5d and 5d. A spline 4s is formed at a fitting portion between the inner peripheral surface of the hub body 4b and the outer peripheral surface of the axle tip portion 2t. On the outer peripheral surface of the hub main body 4b, an inner ring restricting portion 4d for restricting the relative movement in the axial direction of the inner ring 5a with respect to itself is formed so as to protrude in the radial direction. The inner ring restricting portion 4d is an inner wall portion of an annular cutout portion formed on the outer peripheral surface of the hub body.

  On the other hand, an axle insertion hole 4h that penetrates in the axial direction is formed in the hub body 4b. A hub fastening bolt 2v for fastening the hub 4 to the axle 2 is screwed into the tip of the axle 2 at the tip opening of the axle insertion hole 4h. On the other hand, the axial rear end portion 5m of the outer ring 5b is inserted inside the outer ring accommodation hole 3h of the axle case 3 serving as the outer ring attachment portion. A hub mounting flange 5f is formed on the outer peripheral surface of the outer ring 5b so as to protrude in the radial direction. By bringing the hub mounting flange 5f into contact with the peripheral edge of the outer ring receiving hole 3h of the axle case 3, the axle of the outer ring 5b is contacted. The relative movement in the axial direction with respect to the case 3 is restricted. An outer ring fastening portion 5e is integrated with the hub mounting flange 5f, and a bolt insertion hole 5h is formed therethrough. Then, an outer ring fastening bolt 5v serving as a fastening member is screwed into the axle case 3 through the bolt insertion hole 5h, and the outer ring 5b is attached to the axle case 3.

  The hub mounting flange 5f is formed to extend to a position facing the wheel mounting flange 4a in the axial direction in the radial direction. The displacement detector 51 is fixed on the main surface of the hub mounting flange 5f on the vehicle body outer side. By mounting the displacement detection unit 51 on the hub mounting flange 5f, the entire displacement detection system as well as the detected unit 60 can be integrated into the hub unit 6, and the assembly to the vehicle body becomes very easy.

  When only the axial load acting on the axle 2 needs to be detected, a configuration in which the displacement detection unit 51 is provided only at one place is also possible. However, as shown in FIG. 2A, a load acting in the radial direction of the axle (or tire), for example, from the output imbalance of the plurality of displacement detectors 51 that arrange the displacement detectors 51 at a plurality of locations around the axle rotation axis. It is also possible to calculate (for example, road surface half force and frictional force).

  As shown in FIG. 8A, since the reflecting member 60 is provided along the circumferential direction of the wheel mounting flange 4a, the displacement can be measured anywhere in the rotation angle section to which the reflecting member 60 is attached. Thus, the degree of freedom in measurement with respect to the four wheel mounting flanges 4a and thus the rotational phase of the axle can be increased. In the present embodiment, the reflecting member 60 is a ring-shaped mirror member that protrudes from the main surface of the wheel mounting flange 4a. As shown in FIG. 8B, the mirror member 60 can also be disposed in the recess 60 formed in the wheel mounting flange 4a (here, the reflecting surface of the mirror member 60 is the main surface of the wheel mounting flange 4a). It ’s almost the same).

Sectional drawing which shows 1st embodiment of the hub unit with a displacement sensor of this invention. The circuit diagram which shows the structural example of the output circuit of the displacement sensor of FIG. Sectional drawing which shows 2nd embodiment of the hub unit with a displacement sensor of this invention. The schematic diagram which shows an example of an optical displacement detection part. The circuit diagram which shows an example of the output circuit of the optical displacement detection part of FIG. Sectional drawing which shows 3rd embodiment of the hub unit with a displacement sensor of this invention. Sectional drawing which shows 4th embodiment of the hub unit with a displacement sensor of this invention. The top view which shows an example of the arrangement | positioning form of a reflection member and a displacement detection part used with the hub unit with a displacement sensor of FIG. Similarly, sectional drawing which shows the modification of the attachment form of the reflection member with respect to a wheel attachment flange.

Explanation of symbols

2 Axle 3 Axle case 3h Outer ring accommodation hole 4 Hub 4a Wheel mounting part 4b Hub body 4e Detected part (body inner side end face)
5a Inner ring 5b Outer ring 5c Rolling element 5f Hub mounting flange 6,106 Hub unit with displacement sensor 51 Optical displacement detector 52 Light source 56 Reflected light detector 60 Reflective member (detected part)
61 Magnetic sensor (displacement detector)
62 Ferromagnetic detection part 70 Sensor cover

Claims (7)

A hub having a hub main body and a wheel mounting flange provided in a shape protruding radially outward from the outer peripheral surface of the hub main body, to which a tire wheel is mounted on the vehicle body outer side;
On the inner side of the vehicle body from the wheel mounting flange, an inner ring provided to the hub body so as to be integrally rotatable,
An outer ring in which the position in the axial direction is non-rotating and fixed relative to the mounting base on the automobile side on the radially outer side of the inner ring;
A plurality of rolling elements disposed between the inner ring and the outer ring;
A detected portion provided on the hub or the axle so as to cause a displacement in the axial direction according to the axial load level acting on the axle;
A displacement detector for detecting a displacement component in the axial direction of the detected portion in a non-contact manner;
A hub unit with a displacement sensor, which outputs displacement detection information by the displacement detector as information on an axial load applied to the axle. The hub is provided with the detected portion on an end surface on the vehicle body inner side in the axial direction, and a space in the axial direction is provided between the rear end portion of the non-rotating outer ring on the vehicle body inner side and the displacement detection portion. The displacement according to claim 1, wherein a sensor cover is provided to cover the sensor cover in a generated form, and the displacement detector is provided at a position facing the displacement detector inside the sensor cover. Hub unit with sensor. The hub unit with a displacement sensor according to claim 2, wherein the detected portion is formed in a region including a rotation axis on an end surface of the driven wheel side axle disposed on the inner side of the hub body on the vehicle body inner side. 4. The displacement sensor according to claim 3, wherein the hub body has a solid structure in which the axle is integrated, and the detected portion is formed on an end surface of the solid hub body on the vehicle body inner side. With hub unit. The hub unit with a displacement sensor according to any one of claims 1 to 4, wherein the displacement detection unit is configured by a proximity sensor. The said detection part is a reflection member, The said displacement detection part is provided with the light source which irradiates the measurement light to the said reflection member, and the reflected light detection part which detects the reflected light by the said reflection member of the said measurement light. The hub unit with a displacement sensor according to any one of claims 1 to 4. 2. The detection unit is a ferromagnetic body detection unit, and the displacement detection unit is a magnetic sensor that detects a magnetic field change caused by the displacement in the axial direction of the ferromagnetic body detection unit. 5. A hub unit with a displacement sensor according to any one of 4 above.

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