JP2006201157A - Ball bearing unit having displacement measuring device, and ball bearing unit having load measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball bearing unit that can increase displacement in the axial directions of an outer wheel 3 and a hub 4a, based on variations in an axial load and can fully secure measurement accuracy of load. <P>SOLUTION: An encoder 12 where the pitch of a change in the characteristics of a surface to be detected gradually changes in the axial direction is externally fitted and fixed to the hub 4a. Displacement in the axial direction of the outer wheel 3 and hub 4a is detected according to the change in the duty ratio of the detection signal of a sensor 13 that is made to face the encoder 12. Then, the axial load, applied between the outer wheel 3 and the hub 4a, is obtained by the displacement. The ratio d/D of the diameter (d) of respective balls 5, 5 to the pitch circle diameter D is regulated to be in the range of 0.12-0.4, and variations in the duty ratio following the variations of the load are increased, thus solving above problems. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  A ball bearing unit with a displacement measuring device and a ball bearing unit with a load measuring device according to the present invention include a relative displacement amount (radial direction) between an outer ring equivalent member and an inner ring equivalent member combined in a relatively rotatable manner via a plurality of balls. And / or a displacement in the axial direction) or a load. Then, a signal representing a load (one or both of a radial load and an axial load) applied between the outer ring equivalent member and the inner ring equivalent member, obtained through a displacement amount or directly, is obtained from a vehicle such as an automobile. Used to ensure running stability.

  For example, automobile wheels are supported rotatably on a suspension by a rolling bearing unit such as a double-row angular ball bearing unit. In order to ensure the running stability of an automobile, an anti-lock brake system (ABS), a traction control system (TCS), or a vehicle stability control system (described in Non-Patent Document 1, for example) VSC) and other vehicle travel stabilization devices are used. In order to control such various vehicle running stabilization devices, signals such as the rotational speed of the wheels and the acceleration in each direction applied to the vehicle body are required. In order to perform higher-level control, it may be preferable to know the magnitude of a load (one or both of a radial load and an axial load) applied to the rolling bearing unit via the wheel.

  In view of such circumstances, Patent Document 1 describes a rolling bearing unit with a load measuring device capable of measuring a radial load. In the case of the first example of this conventional structure, the outer ring and the hub are measured by measuring the radial displacement between the outer ring that does not rotate and the hub that rotates on the inner diameter side of the outer ring with a non-contact type displacement sensor. The radial load applied between and is calculated. The obtained radial load is used not only to properly control the ABS but also to inform the driver of a bad loading condition.

  Patent document 2 describes a structure for measuring an axial load applied to a rolling bearing unit. In the case of the second example of the conventional structure described in Patent Document 2, bolts for connecting the fixed side flange to the knuckle are screwed at a plurality of positions on the inner side surface of the fixed side flange provided on the outer peripheral surface of the outer ring. Each load sensor is attached to a portion surrounding the screw hole. Each load sensor is clamped between the outer surface of the knuckle and the inner surface of the fixed flange in a state where the outer ring is supported and fixed to the knuckle. In the case of the load measuring device for the rolling bearing unit of the second example having such a conventional structure, the axial load applied between the wheel and the knuckle is measured by the load sensors. Further, in Patent Document 3, a strain gauge for detecting dynamic strain is provided in a member corresponding to an outer ring whose rigidity is partially reduced, and the revolution speed of the rolling element is determined from the passing frequency of the rolling element detected by the strain gauge. Furthermore, a method for measuring an axial load applied to a rolling bearing is described.

  In the case of the first example of the conventional structure described in Patent Document 1, the load applied to the rolling bearing unit is measured by measuring the displacement in the radial direction between the outer ring and the hub by the displacement sensor. However, since the displacement amount in the radial direction is small, it is necessary to use a highly accurate displacement sensor in order to obtain this load with high accuracy. Since high-precision non-contact sensors are expensive, it is inevitable that the cost of the entire rolling bearing unit with a load measuring device increases.

  In the second example of the conventional structure described in Patent Document 2, it is necessary to provide as many load sensors as the bolts for supporting and fixing the outer ring to the knuckle. For this reason, coupled with the fact that the load sensor itself is expensive, it is inevitable that the cost of the entire load measuring device of the rolling bearing unit is considerably increased. In addition, the method described in Patent Document 3 needs to lower the rigidity of a part of the outer ring equivalent member, which may make it difficult to ensure the durability of the outer ring equivalent member, and obtain sufficient measurement accuracy. Things are considered difficult.

  In view of such circumstances, the inventors of the present invention first fixed and supported an encoder on the rotation side raceway of the double row angular type ball bearing unit, concentrically with the rotation side raceway. An invention (prior invention) for obtaining a relative displacement amount between the rotation side raceway and the stationary side raceway by detecting the displacement of the detection surface was made (Japanese Patent Application No. 2005-147642). In the case of the structure according to the previous invention, the pitch or phase at which the characteristic of the detected surface of the encoder changes with respect to the circumferential direction changes continuously with respect to the width direction of the detected surface, which coincides with the direction of displacement to be detected. is doing. Then, the detection unit of the sensor supported on the stationary part such as the stationary side race ring is brought close to and opposed to the detection surface of the encoder so that the output signal of the sensor changes according to the relative displacement amount. ing.

8 to 9 show a first example of such a structure according to the prior invention. The ball bearing unit with a displacement measuring device and the ball bearing unit with a load measuring device according to the first embodiment of the present invention have a function as a wheel support ball bearing unit 1 and a rotational speed detecting device (or load). Measuring device, the same applies hereinafter) 2.
Among these, as shown in FIG. 8, the wheel bearing ball bearing unit 1 includes an outer ring 3, a hub 4, and a plurality of balls 5, 5 each made of steel such as medium carbon steel or bearing steel. Is provided. Of these, the outer ring 3 is a stationary-side bearing ring that is supported and fixed to the suspension device in use. The outer ring 3 has double-row outer ring raceways 6 and 6 connected to the suspension surface on the outer peripheral surface. Each has an outward flange-shaped attachment portion 7. The hub 4 is a rotating raceway that supports and fixes a wheel in use and rotates together with the wheel. The hub body 8 and the inner ring 9 are combined and fixed. Such a hub 4 includes a flange 10 for supporting and fixing a wheel to an outer peripheral end portion in the axial direction of the outer peripheral surface (an end portion on the outer side in the width direction of the vehicle body when assembled to the suspension device). Double-row inner ring raceways 11 are provided on the outer circumferential surface of the inner ring 9. Each of the balls 5 and 5 is provided with a plurality of contact angles in the opposite directions (rear combination type) between the inner ring raceways 11 and 11 and the outer ring raceways 6 and 6, respectively. The hub 4 is rotatably provided, and the hub 4 is supported on the inner diameter side of the outer ring 3 so as to be rotatable concentrically with the outer ring 3.

On the other hand, as shown in FIG. 8, the displacement measuring apparatus 2 includes an encoder 12, a sensor 13, and an arithmetic unit (not shown).
Of these, the encoder 12 is made of a magnetic material such as a mild steel plate, and has a plurality of through holes 14a and 14b each having a slit shape. These through holes 14 a and 14 b are inclined with respect to the direction of the central axis of the encoder 12. Further, the inclination directions are opposite to each other between the through holes 14a and 14b adjacent in the circumferential direction. Further, the pitch between the through holes 14a and 14b adjacent in the circumferential direction alternately repeats the magnitude. Such an encoder 12 is fitted and fixed to the intermediate portion of the hub 4. On the other hand, the sensor 13 is provided in a mounting hole 15 formed in the intermediate portion of the outer ring 3 in a state of being inserted from the radially outer side to the inner side, and the detection portion provided at the tip portion is an inner peripheral surface of the outer ring 3. Is projected inward in the radial direction from the outer peripheral surface of the encoder 12, which is a surface to be detected.

  In the case of the first example of the displacement measuring device of the prior invention configured as described above, the detection signal of the sensor 13 changes when the hub 4 and the outer ring 3 are relatively displaced in the axial direction based on the axial load. Changes. Therefore, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained based on the change in the pattern. Note that the period in which the detection signal changes based on the through holes 14a and 14a (14b and 14b) inclined in the same direction does not change regardless of the relative displacement. Therefore, the rotational speed of the hub 4 can be obtained based on this cycle.

  Next, FIG. 10 shows an encoder 12a incorporated in the second example of the structure according to the previous invention. The encoder 12a is formed in a cylindrical shape by a magnetic metal plate, and slit-like through holes 14c and 14d are provided in one half and the other half in the width direction, respectively, and the direction of the central axis of the encoder 12a. Are formed at equal intervals in the circumferential direction. The inclination direction of the through holes 14c, 14c in the half half of the width direction is opposite to the inclination direction of the through holes 14d, 14d in the other half part. On the outer peripheral surface of such an encoder 12a, the detection portions of a pair of sensors arranged in a state of being separated in the axial direction are made to face each other.

  In the case of the second example of the displacement measuring device of the present invention configured to include the encoder 12a as described above, when the hub and the outer ring are relatively displaced in the axial direction based on the axial load, the detection signals of the pair of sensors are detected. Is out of phase. Therefore, based on the magnitude of the deviation, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained. The rotational speed of the hub is obtained based on the detection signal of any sensor.

  Next, FIGS. 11 to 12 show a third example of the structure according to the previous invention. In the case of the third example of the present invention, the base end portion of the encoder 12b as shown in FIG. 12 is externally fitted to the inner end portion of the inner ring 9 which is externally fitted and fixed to the inner end portion of the hub 4. 12b is supported and fixed to the hub 4 concentrically with the hub 4. The encoder 12b is made of a magnetic metal plate, and has slit-shaped through-holes 14e and 14e formed at equal intervals in the circumferential direction in a cylindrical portion provided in the first half. . In addition, a pair of sensors are held in an axially separated state in a sensor holder 17 supported by a cover 16 fitted and fixed to the inner end of the outer ring 3. And the detection part of these both sensors is made to oppose and approach the internal peripheral surface of the said encoder 12b.

  Also in the case of the third example of the displacement measuring device of the prior invention as described above, when the hub 4 and the outer ring 3 are relatively displaced in the axial direction based on the axial load, the detection signals of the pair of sensors are out of phase. Therefore, based on the magnitude of the deviation, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained. The rotational speed of the hub 4 is obtained based on the detection signal of any sensor.

  Next, FIG. 13 shows an encoder 12c incorporated in the fourth example of the structure according to the previous invention. The encoder 12c is formed in an annular shape by a magnetic metal plate, and trapezoidal through holes 14f and 14f are formed at equal intervals in the circumferential direction. is doing. The sensor detection unit is placed in close proximity to one axial side surface of the encoder 12c.

  In the case of the fourth example of the displacement measuring device of the present invention configured to include the encoder 12c as described above, when the hub and the outer ring are relatively displaced in the radial direction based on the radial load, the duty ratio of the detection signal of the sensor (High potential duration / one cycle) changes. Therefore, the magnitude of the relative displacement and further the magnitude of the radial load can be obtained based on the duty ratio. The rotational speed of the hub is determined based on the period of the detection signal of the sensor.

  In the first to fourth examples of the above-described displacement measuring device of the present invention, the encoders 12 to 12c are each made of a simple magnetic material and are intended to incorporate a permanent magnet on the sensor side. On the other hand, the Japanese Patent Application No. 2005-147642 describes a structure in which a permanent magnet encoder is used and the permanent magnet on the sensor side is omitted. Further, it describes a structure in which an encoder made of a magnetic material in which concave portions and convex portions are alternately formed on a surface to be detected and a sensor incorporating a permanent magnet are combined. In any case, the pitch or phase at which the detected surface of the encoder changes in the circumferential direction continuously changes in the width direction of the detected surface, which coincides with the direction of displacement to be detected.

  In any case, the displacement amount in the radial direction or the axial direction obtained by the ball bearing unit with a displacement measuring device according to the previous invention as described above is the radial force applied between the rotating side bearing ring and the stationary side bearing ring. Related to load or axial load (proportional or close to proportional). Therefore, the radial load or the axial load can be obtained from the displacement amount. Further, the load (one or both of the radial load and the axial load) obtained through the displacement amount in this way or directly obtained by the ball bearing unit with a load measuring device without involving the displacement amount is the road surface and the wheel. This is equivalent to the load generated on the contact surface with the (tire). Therefore, if the control for stabilizing the running state of the vehicle is performed based on the obtained load, the feed forward control for preventing the posture of the vehicle from becoming unstable becomes possible. Advanced control to ensure stability is possible.

  By the way, when implementing the ball bearing unit with a displacement measuring device or the ball bearing unit with a load measuring device according to the above-described invention, it is necessary to pay attention to the following points. That is, in order to improve the measurement accuracy of the radial load or the axial load, it is desirable that the relative displacement amount between the rotating side raceway and the stationary side raceway is large based on the variation of each load. On the other hand, depending on the specifications of the ball bearing unit in which the displacement measuring device or the load measuring device is incorporated, the rotation side raceway and the stationary side raceway are slightly displaced relatively regardless of the variation of each load. There is. In such a case, it becomes difficult to ensure sufficient measurement accuracy of each load.

JP 2001-21577 A Japanese Patent Laid-Open No. 3-209016 Japanese Patent Publication No.62-3365 Motoo Aoyama, “Red Badge Super Illustrated Series / A book that shows the latest mechanics of cars”, p. 138-139, p. 146-149, Sangensha Co., Ltd./Kodansha Co., Ltd., December 20, 2001

  In view of the circumstances as described above, the present invention can increase the relative displacement amount between the rotating side raceway and the stationary side raceway based on the load variation, and sufficiently ensure the load measurement accuracy based on this relative displacement amount. Invented to realize a ball bearing unit with a displacement measuring device and a ball bearing unit with a load measuring device.

Of the ball bearing unit with a displacement measuring device and the ball bearing unit with a load measuring device according to the present invention, the ball bearing unit with a displacement measuring device includes a ball bearing unit and a displacement measuring device.
Of these, the ball bearing unit is composed of a steel stationary bearing ring that does not rotate even in use, a steel rotating bearing ring that rotates in use, and the stationary bearing ring and the rotating bearing ring facing each other. And a plurality of balls, each made of steel, provided with a contact angle between the stationary-side track and the rotating-side track existing on the peripheral surface. And the ratio of the diameter of each of these balls and the pitch circle diameter of each of these balls is regulated within the range of 0.12 to 0.4.
The displacement measuring device includes an encoder that is supported concentrically with the rotation-side raceway on a part of the rotation-side raceway, and whose detection surface characteristics are alternately changed in the circumferential direction, and a detection unit thereof. And a sensor that changes the output signal in response to a change in the characteristics of the detected surface, and the stationary side based on the output signal of the sensor. An arithmetic unit that calculates a relative displacement amount between the raceway and the rotation-side raceway.
The pitch or phase at which the characteristics of the surface to be detected change in the circumferential direction continuously changes in the width direction of the surface to be detected, which coincides with the direction of displacement to be detected.
In addition, in order to obtain the load acting between the rotation side raceway and the stationary side raceway, it is not always necessary to obtain the relative displacement amount between the rotation side raceway and the stationary side raceway. That is, as described in claim 6, based on the output signal of the sensor, a load acting between the stationary side raceway and the rotation side raceway is directly calculated (the relative displacement amount is obtained). It is also possible to have a function to calculate (without going through the process).

  When the ball bearing unit with a displacement measuring device and the ball bearing unit with a load measuring device of the present invention configured as described above are used, the output signal of the sensor is sent to the calculator. Then, this computing unit calculates the load acting between the stationary side raceway and the rotation side raceway, directly or via the relative displacement amount of both raceways, based on the output signal of this sensor. That is, when a load is applied to the ball bearing unit, the stationary side raceway and the rotation side raceway are relatively displaced on the basis of the elastic deformation of the components of the ball bearing, and of these, the rotation side raceway The change pattern of the output signal of the sensor corresponding to the change in the characteristics of the detected surface of the encoder supported by the encoder changes. Therefore, based on this change pattern, the relative displacement amount between the stationary side raceway and the rotation side raceway, and the load acting between the stationary side raceway and the rotation side raceway are obtained.

  In particular, in the case of the ball bearing unit with a displacement measuring device and the ball bearing unit with a load measuring device of the present invention, the ratio of the diameter of each ball to the pitch circle diameter of each ball is in the range of 0.12-0.4. Along with the restriction, the relative displacement amount between the stationary-side raceway and the rotation-side raceway can be increased based on the load variation. For this reason, it becomes easy to measure this relative displacement amount, and it is possible to sufficiently ensure the measurement accuracy of the load based on this relative displacement amount. This point will be described with reference to FIGS.

  Of these, FIG. 1 shows a ball bearing unit 1a for supporting a wheel as a premise of a simulation performed to confirm the effect of the present invention. The wheel support ball bearing unit 1a is for supporting driving wheels (front wheels of FF vehicles, rear wheels of FR vehicles and MR vehicles, all wheels of 4WD vehicles) on a suspension device, and constitutes a hub 4a. A spline hole 18 for inserting a spline shaft attached to the constant velocity joint is provided at the center of the hub body 8a. The structure of such a wheel support ball bearing unit 1a has been widely known and is not the gist of the present invention. The target wheel support ball bearing unit is for a drive wheel as shown in FIG. 1 or a driven wheel as shown in FIGS. 8 and 11 (rear wheel of FF vehicle, FR vehicle and MR vehicle). It does not relate to the gist of the present invention whether it is for a front wheel of a car. Whether the structure shown in FIG. 1 or the structure shown in FIGS. 8 and 11, the ratio d / D between the diameter d of the balls 5, 5 and the pitch circle diameter D of the balls 5, 5 is different. As the axial load varies, the degree of relative displacement between the outer ring 3 and the hub 4a varies in the axial direction.

  The simulation and consideration are as follows. The diameter d of the balls 5, 5 arranged in a double row and the pitch circle diameter D of the balls 5, 5 constituting the double row angular type wheel support ball bearing unit 1a. The ratio d / D was determined in order to know the influence on the relative displacement in the axial direction between the outer ring 3 and the hub 4a due to the variation of the axial load, and to determine the appropriate range of the ratio d / D. 1A shows a ball bearing unit having a relatively small ratio d / D (0.15), and FIG. 1B shows a ball bearing unit having a relatively large ratio d / D (0.25). , Respectively. Note that a preload was applied to each of the balls 5 and 5.

  In order to obtain the relative displacement in the axial direction, it was considered that an encoder made of a permanent magnet was fitted and fixed to the intermediate portion of the hub body 8a. On the outer peripheral surface of the encoder, which is the surface to be detected, the S pole and the N pole are alternately attached at equal intervals in the circumferential direction. The magnetization ranges of these S poles and N poles are each trapezoidal, and the width in the circumferential direction of each is gradually changed in the axial direction of the encoder. That is, the width of the S pole gradually increases from one axial end to the other end, and the width of the N pole gradually decreases from one axial end to the other end. Therefore, the boundary between the S pole and the N pole adjacent in the circumferential direction is inclined by a predetermined angle with respect to the direction of the central axis of the encoder. This predetermined angle was 45 degrees. The encoder has a diameter of 60 mm, and the total of S and N poles present on the outer peripheral surface of the encoder is 96.

  When the detection portion of the sensor is opposed to the outer peripheral surface of such an encoder, the detection signal of this sensor changes with the rotation of the hub 4a. The period of change of the detection signal is inversely proportional to the rotational speed of the hub 4a regardless of the position of the detection unit in the axial direction of the outer peripheral surface of the encoder. On the other hand, the detection signal change pattern (duty ratio or phase difference between detection signals of a pair of sensors) is such that the detection unit faces any part in the axial direction of the outer peripheral surface of the encoder. It depends on whether or not Therefore, the relative displacement amount in the axial direction and further the axial load can be obtained based on the duty ratio or the phase difference. In this case, the greater the change in the duty ratio or phase difference based on the relative displacement amount, the more accurately the relative displacement amount in the axial direction, and thus the axial load, can be obtained with higher accuracy. Therefore, a computer simulation was performed on the relationship between the axial load and the duty ratio or phase difference.

  FIG. 2 shows the relationship between the axial load and the duty ratio or phase difference. In FIG. 2, the solid line A is the above when the ratio d / D is 0.1, the broken line B is also 0.25, and the chain line C is 0.4, respectively. The relationship between the axial load and the amount of change in the duty ratio or phase difference is shown. FIG. 2 shows the case where the outer ring 3 and the hub 4a are made of medium carbon steel, and the balls 5 and 5 are made of bearing steel.

  As apparent from FIG. 2, if the ratio d / D between the diameter d of the balls 5 and 5 and the pitch circle diameter D of the balls 5 and 5 is increased, the variation in the axial load is caused. The displacement in the axial direction between the outer ring 3 and the hub 4a can be increased to increase the variation in the duty ratio or phase difference. FIG. 3 shows the effect of the ratio d / D between the diameter d of each ball 5, 5 and the pitch circle diameter D on the duty ratio or phase difference variation of the detection signal of the sensor accompanying the variation of the axial load. Is shown. The horizontal axis in FIG. 3 represents the ratio d / D. The vertical axis represents the degree of the gradient of each line A to C in FIG. 2 to the extent that the duty ratio or phase difference of the detection signal varies with the variation of the axial load. Specifically, this is the ratio (point [%]) at which the duty ratio or phase difference of the detection signal of the sensor varies when the axial load changes by 7000 N. For example, when the ratio d / D is 0.1, when the axial load changes by 7000 N, the duty ratio or the phase difference of the detection signal changes by about 1.4 points [%].

  As is clear from FIGS. 2 and 3 as described above, in order to increase the change in the duty ratio or phase difference of the detection signal based on the variation in the axial load and improve the measurement accuracy of the axial load, the ratio What is necessary is just to enlarge d / D. In other words, when the ratio d / D is too small, the measurement accuracy of the axial load cannot be sufficiently ensured. However, if the diameter d of each of the balls 5 and 5 is excessively increased in order to increase the ratio d / D, the entire ball bearing unit becomes large (in the case where the outer diameter of the outer ring 3 is increased), or the outer ring 3 In addition, the thickness of the hub 4a becomes too small, and the durability of the outer ring 3 and the hub 4a may be impaired. If the pitch circle diameter D is reduced to increase the ratio d / D, the rigidity against moment load and the rolling fatigue life may be reduced. Therefore, the ratio d / D cannot be increased unnecessarily.

Therefore, the present inventor increases the change in the duty ratio or phase difference of the detection signal of the sensor based on the axial load while ensuring the original function of the ball bearing unit, and can ensure the measurement accuracy of the axial load. Considered to know.
First, in consideration of the use of the present invention for the control of a vehicle running stabilizer such as ABS, TCS, VSC, etc., in order to stabilize the running state of the vehicle, the resolution for detecting the axial load is 1000 N. It is necessary to suppress the degree to about 500N, preferably about 500N. If the resolution is worse than this (measurement can only be performed with a resolution higher than 1000 N), there is no point in using the axial load for control for ensuring running stability. Further, when this axial load is used for this control, about -1000N to 6000N (full scale is about 7000N) is necessary for the measurement range of this axial load.

  On the other hand, when detecting the axial load, there is a detection error of a sensor that changes its output signal in response to a change in the characteristics of the detected surface of the encoder. For example, when this sensor is an active magnetic sensor incorporating a magnetic detection element such as a Hall element or a magnetoresistive element, the detection error of this sensor needs to be considered about 0.2%. When the resolution of the axial load is larger (bad) than the detection error, there is a possibility that the reliability of control by the axial load cannot be sufficiently secured.

  For example, the magnitude of the axial load is determined by dividing it into a plurality of hierarchies (for example, 7 to 14 hierarchies) between the full scales, and ABS, TCS, VSC according to the hierarchy to which the axial load generated at that time belongs. When the vehicle running stabilization device such as the above is controlled, there is a possibility that the hierarchy to which the axial load actually acting belongs and the hierarchy to which the axial load calculated by the computing unit is shifted by two or more stages. If the resolution for detecting this axial load is about 1000 N as described above, preferably about 500 N, it is possible to avoid the above-described two-stage shift or more. In order not to cause such a shift of two or more steps, when the axial load fluctuates 1000 N (preferably 500 N), the duty ratio or phase difference of the detection signal of the sensor is 0.2 point [% It is necessary to have a structure that varies. In this case, it is necessary that the duty ratio or phase difference of the detection signal fluctuates by 1.4 points [%] or more in the entire measurement range (−1000 N to 6000 N, full scale: 7000 N). 0.2 points × (7000 N / 1000 N) = 1.4 points}. Note that the one-stage deviation cannot be eliminated as long as there is even a slight detection error in consideration of the possibility that the actually acting axial load is present in the vicinity of the boundary of the hierarchical division.

If FIG. 3 is seen on such a premise, it is necessary to make ratio d / D of the diameter d of each said balls 5 and 5 and the pitch circle diameter D of these each balls 5 and 5 more than 0.12. I understand. That is, the value of 0.12 can be derived by reading the value of the ratio d / D where the vertical axis of FIG. 3 is 1.4 points from the horizontal axis of FIG.
Further, when the ratio d / D is 0.4, the change of the duty ratio or the phase difference of the detection signal based on the variation of the axial load is approximately 2.45 points [% in the full scale range of 7000 N. ]fluctuate. Therefore, the axial load can be measured with a resolution of about 570N. If the predetermined angle is made slightly larger than 45 degrees, a resolution of about 500 N can be realized. If the ratio d / D is made larger than 0.4, the resolution of this axial load can be further improved. However, if the diameter d of each of the balls 5 and 5 is increased or the pitch circle diameter D of each of these balls is decreased so that the ratio d / D is greater than 0.4, the original ball bearing unit Performance is impaired. On the other hand, in the case of the present invention, since the ratio d / D is set to 0.12 to 0.4, the accuracy of measuring the axial load is sufficiently secured while ensuring the original performance of the ball bearing unit. it can.

More preferably, the ratio d / D is restricted to a range of 0.2 to 0.3. If the ratio d / D is regulated in this way, it is possible to improve the measurement accuracy of the axial load while preventing an increase in the size of the ball bearing unit and an excessive decrease in the thickness of the outer ring 3 and the hub 4a.
Of the two ball bearing units shown in FIG. 1, the structure shown in FIG. 1A has the ratio d / D of 0.15 and the detection signal in the full scale range of 7000N. The change in the duty ratio or phase difference is 1.6 points, and the resolution is 875 N.
In the structure shown in (B), the ratio d / D is 0.25, the change in the duty ratio or phase difference of the detection signal is 2.0 points in the full scale range of 7000 N, and the resolution Is 700N.

  As described above, the degree of change in the duty ratio or phase difference of the detection signal with the variation in the axial load is the ratio d between the diameter d of the balls 5 and 5 and the pitch circle diameter D of the balls. It can be increased by increasing / D. However, the degree to which the duty ratio or phase difference of the detection signal changes is formed on the diameter d of the balls 5, 5 and the outer ring raceways 6 and 6 formed on the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the hub 4a. It can also be adjusted by the ratio (r / d) with the radius of curvature r of the cross section of the inner ring raceways 11, 11. In other words, the degree of change can be changed by changing the ratio r / d to change the degree of linearity (linearity) and gain. In practice, the ratio r / d can be adjusted in the range of 0.505 to 0.6. The value of the ratio r / d within the above range is based on the experimental results depending on the required linearity (linearity), gain (gradient), the range in which the axial load can be measured, and the like. And design it. 2 to 3 show the case where r / d is a standard value (0.52 to 0.53). The contact angles of the balls 5 and 5 are shown in the case of standard values (30 to 40 degrees).

The linearity and gain characteristics can also be changed by changing the preload applied to the balls 5 and 5. In this case, the preload can be changed in the range of 980N to 9800N (100 kgf to 1000 kgf). FIGS. 2 to 3 show the case where the preload value is a standard value (about 1960 N).
Various methods for changing the degree of change in the duty ratio or phase difference of the detection signal in accordance with the variation of the axial load as described above may be employed independently or in combination.
When the present invention is carried out, as shown in FIGS. 1 and 2, not only the ratio d / D between the diameter d and the pitch circle diameter D is increased for the balls 5 and 5 in both rows, Only the ratio d / D can be increased. Further, the present invention can be applied not only to a double row ball bearing unit but also to a single row ball bearing unit.
Furthermore, not only when measuring the axial load, but also when measuring the radial load, the same concept can be applied.

  When carrying out the present invention, for example, as described in claims 2 and 7, a first detected portion and a second detected portion having different characteristics are arranged on the detected surface of the encoder in the circumferential direction. Are arranged alternately and at equal intervals. Of the widths of the two detected portions in the circumferential direction, the width of the first detected portion is wider toward one side in the width direction of the detected surface, and the width of the second detected portion is the width of the detected surface. Widen the other side in the width direction. In this case, the output signal of the sensor is a pulse signal or a sine wave signal that changes a value related to the period or amplitude in accordance with the difference in the width in the circumferential direction between the first detected part and the second detected part It becomes. Then, the computing unit obtains a relative displacement amount or a load acting between the stationary side raceway and the rotation side raceway based on the signal representing the ratio regarding the period or the amplitude.

  Alternatively, as described in claims 3 and 8, a plurality of detection combination parts each including a pair of individualized parts each having a characteristic different from that of the other parts are provided on the detection target surface of the encoder in the circumferential direction. Place them at regular intervals. The intervals in the circumferential direction between each pair of individualized portions constituting each detected combination part are continuously in the same direction with respect to the width direction of the detected surface in all the detected combination parts. Change. In this case, the phase of the change in the output signal of the sensor changes in accordance with the position in the width direction of the detected surface of the encoder that the detection unit of the sensor faces. Then, the computing unit obtains a relative displacement amount or a load acting between the stationary side raceway and the rotation side raceway based on the signal representing the phase of the change.

Alternatively, as described in claims 4 and 9, a pair of sensors installed with the respective detection units positioned at positions separated in the width direction of the detected surface of the encoder are provided. And the part where the detection part of at least one sensor opposes in this to-be-detected surface inclines the boundary where a characteristic changes regarding the circumferential direction with respect to the said width direction. In this case, the phase of the change in the output signal of the at least one sensor changes in accordance with the position in the width direction of the detected surface of the encoder that the detection unit of the sensor faces. Then, the computing unit obtains a relative displacement amount or a load acting between the stationary side raceway and the rotation side raceway based on the signal representing the phase of the change.
In any case, the displacement in the width direction of the detected surface of the encoder can be reliably measured.

Further, when carrying out the present invention, preferably, as described in claim 5, the ball bearing unit with the displacement measuring device is supported on the suspension device of the automobile so that the wheels can rotate freely, and these wheels and the suspension device. Used to obtain the load acting between the two.
If the present invention is carried out in such a state, the load applied between the wheel and the suspension device can be obtained, and the vehicle running stabilization device such as ABS, TCS, VSC or the like can be appropriately controlled.

  FIG. 4 shows Embodiment 1 of the present invention corresponding to claims 1, 3, 5, 6 and 8. In the case of the present embodiment, the intermediate portion of the hub 4a, which comprises the hub body 8a made of medium carbon steel and the inner ring 9 made of bearing steel, constituting the wheel bearing ball bearing unit 1a for driving wheel support, is described above. The encoder 12 as shown in FIG. 9 is externally fixed. And the sensor 13 is provided in the attachment hole 15 formed in the intermediate part of the outer ring 3 made of medium carbon steel in a state of being inserted from the radially outer side to the inner side, and the detection part provided at the tip part of the sensor 13 is the above-mentioned It protrudes radially inward from the inner peripheral surface of the outer ring 3 and is close to and opposed to the outer peripheral surface of the encoder 12, which is a detected surface.

  In this embodiment, the ratio d / D between the diameter d of each ball 5, 5 and the pitch circle diameter D, each made of bearing steel, is 0.15. Therefore, when the inclination angle of the through holes 14a and 14b formed in the encoder 12 with respect to the direction of the central axis of the encoder is 45 degrees, the range is about -1000N to 6000N (full scale is about 7000N). The duty ratio of the detection signal of the sensor 13 can be changed by about 1.6 points (%). The axial load applied between the hub 4a and the outer ring 3 can be measured with a resolution of about 875N. As a result, the axial load obtained based on the detection signal of the sensor 13 can be effectively used for control for ensuring running stability.

  In place of the encoder as shown in FIG. 9, an encoder that is entirely cylindrical and has a trapezoidal or triangular through hole (see FIG. 13 for the trapezoidal through hole) is fitted around the intermediate portion of the hub 4a. If fixed, the structure corresponding to claims 1, 2, 5, 6, and 7 can be implemented. As described above, a permanent magnet encoder having a trapezoidal magnetization range, or an encoder made of a magnetic material in which concave portions and convex portions each having a trapezoid shape are alternately formed on the detection surface may be used. It is the same.

  Next, FIG. 5 shows Embodiment 2 of the present invention corresponding to claims 1, 4, 5, 6 and 9. In the case of the present embodiment, an encoder 12a as shown in FIG. 10 is externally fitted and fixed to an intermediate portion of the hub 4a constituting the wheel support ball bearing unit 1a for driving wheel support. Then, the detection portions of the sensors 13a and 13b mounted in the mounting hole 15 portion formed in the intermediate portion of the outer ring 3 are closely opposed to two axially spaced positions on the outer peripheral surface of the encoder 12a which is the detection surface. I am letting. The sensors 13 a and 13 b are provided at the tip of a single sensor holder inserted through the mounting hole 15 in a state of being separated in the axial direction of the outer ring 3.

  Also in this embodiment, the ratio d / D between the diameter d of each ball 5, 5 and the pitch circle diameter D is set to 0.15. Therefore, when the inclination angle of the through holes 14c and 14d formed in the encoder 12a with respect to the direction of the central axis of the encoder is 45 degrees, the range is about -1000N to 6000N (full scale is about 7000N). The phase difference between the detection signals of the sensors 13a and 13b can be changed by about 1.6 points (%). The axial load applied between the hub 4a and the outer ring 3 can be measured with a resolution of about 875N. As a result, the axial load obtained based on the phase difference between the detection signals of both the sensors 13a and 13b can be effectively used for control for ensuring running stability. The phase difference change point is a value (phase difference / cycle) obtained by dividing the phase difference between the detection signals of the sensors 13a and 13b by the period of the sensors 13a and 13b.

  FIG. 6 shows Embodiment 3 of the present invention corresponding to claims 1, 3, 5, 6, and 8. In this embodiment, the ratio d / D between the diameter d of each ball 5, 5 and the pitch circle diameter D is 0.25. Therefore, in the case of the present embodiment, the duty ratio of the detection signal of the sensor 13 is changed by about 2.0 points (%) within a range of about −1000 N to about 6000 N (full scale is about 7000 N). The axial load applied to the outer ring 3 can be measured with a resolution of about 700N. Other configurations and operations are the same as those of the first embodiment.

  Next, FIG. 7 shows Embodiment 4 of the present invention corresponding to claims 1, 4, 5, 6 and 9. In this embodiment, the ratio d / D between the diameter d of each ball 5, 5 and the pitch circle diameter D is 0.25. Therefore, in the case of the present embodiment, the phase difference between the detection signals of the sensors 13a and 13b is changed by about 2.0 points (%) within a range of about -1000N to 6000N (full scale is about 7000N), The axial load applied between the hub 4a and the outer ring 3 can be measured with a resolution of about 700N. Other configurations and operations are the same as those of the second embodiment described above.

Sectional drawing which shows two examples of the ball bearing unit used for the simulation for confirming the effect of this invention. A diagram showing the relationship between the axial load and the degree of change in the duty ratio or phase difference of the detection signal of the sensor for each of three types of samples in which the ratio of the diameter of each ball and the pitch circle diameter of each ball is different from each other. . The diagram which shows the influence which the difference in the ratio of the diameter of each ball | bowl and the pitch circle diameter of these each ball | bowl has on the fluctuation | variation of the duty ratio or phase difference of the detection signal of a sensor accompanying the fluctuation | variation of an axial load. Sectional drawing which shows Example 1 of this invention. Sectional drawing which shows the same Example 2. FIG. Sectional drawing which shows the same Example 3. FIG. Sectional drawing which shows the same Example 4. FIG. Sectional drawing of the 1st example of the ball bearing unit with a displacement measuring device which concerns on a prior invention. The perspective view of the encoder built in this 1st example. The perspective view of the encoder integrated in the 2nd example of the ball bearing unit with a displacement measuring device which concerns on a prior invention. Sectional drawing of the 3rd example of the ball bearing unit with a displacement measuring device which concerns on a prior invention. Sectional drawing of the encoder integrated in this 3rd example. The side view which looked at the encoder built in the 4th example of the ball bearing unit with a displacement measuring device concerning a prior invention from the axial direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Wheel support unit for wheel support 2 Displacement measuring device 3 Outer ring 4, 4a Hub 5 Ball 6 Outer ring raceway 7 Mounting portion 8, 8a Hub body 9 Inner ring 10 Flange 11 Inner ring raceway 12, 12a, 12b, 12c Encoder 13, 13a , 13b Sensors 14a, 14b, 14c, 14d, 14e, 14f Through hole 15 Mounting hole 16 Cover 17 Sensor holder 18 Spline hole

Claims (9)

A ball bearing unit and a displacement measuring device;
Of these, the ball bearing unit is composed of a steel stationary bearing ring that does not rotate even in use, a steel rotating bearing ring that rotates in use, and the stationary bearing ring and the rotating bearing ring facing each other. A plurality of balls, each made of steel, provided with a contact angle between the stationary-side track and the rotating-side track existing on the circumferential surface, and the diameters of these balls and these The ratio with the pitch circle diameter of each ball is regulated within the range of 0.12-0.4,
The displacement measuring device includes an encoder that is supported concentrically with the rotation-side raceway on a part of the rotation-side raceway, and in which the characteristics of the surface to be detected are alternately changed with respect to the circumferential direction, and its detection unit. A sensor that is supported by a portion that does not rotate in a state of being opposed to the detection surface and changes its output signal in response to a change in the characteristics of the detection surface, and based on the output signal of the sensor, And a calculator for calculating a relative displacement amount between the rotating side raceway and the rotation side raceway,
The pitch or phase at which the characteristics of the detected surface change with respect to the circumferential direction is continuously changing with respect to the width direction of the detected surface, which coincides with the direction of displacement to be detected.
Ball bearing unit with displacement measuring device.   On the detection surface of the encoder, the first detection portion and the second detection portion having different characteristics are alternately arranged at equal intervals in the circumferential direction, and the circumferential direction of these detection portions is related to the circumferential direction. Of the widths, the width of the first detected portion is wider on one side in the width direction of the detected surface, the width of the second detected portion is wider on the other side in the width direction of the detected surface, and the output signal of the sensor is , A pulse-like signal or a sine wave-like signal that changes a value related to the period or amplitude in accordance with the difference in the width in the circumferential direction between the first detected part and the second detected part. Alternatively, the ball bearing unit with a displacement measuring device according to claim 1, wherein the relative displacement is obtained based on a signal representing a ratio related to amplitude.   On the detected surface of the encoder, a plurality of detected combination parts each consisting of a pair of individualized parts having different characteristics from the other parts are arranged at equal intervals in the circumferential direction. The intervals in the circumferential direction between each pair of individualized parts constituting the combination part for detection are continuously changed in the same direction with respect to the width direction of the detected surface in all the combination parts for detection. The phase of the change in the output signal of the sensor changes corresponding to the position in the width direction of the detected surface of the encoder facing the detection unit of the sensor. The ball bearing unit with a displacement measuring device according to claim 1, wherein a relative displacement amount is obtained based on a signal to be expressed.   A pair of sensors installed with the respective detection units positioned at positions separated in the width direction of the detection surface of the encoder are provided, and the detection units of at least one of the detection surfaces are opposed to each other. In the encoder, the boundary where the characteristic changes in the circumferential direction is inclined with respect to the width direction, and the phase of the change in the output signal of the at least one sensor is opposed to the detection unit of the sensor. The ball bearing with a displacement measuring device according to claim 1, wherein the arithmetic unit calculates a relative displacement amount based on a signal representing a phase of the change. unit.   The displacement measuring device according to any one of claims 1 to 4, which is used to rotatably support a wheel on a suspension device of an automobile and to obtain a load acting between the wheel and the suspension device. Ball bearing unit. A ball bearing unit and a load measuring device;
Of these, the ball bearing unit is composed of a steel stationary bearing ring that does not rotate even in use, a steel rotating bearing ring that rotates in use, and the stationary bearing ring and the rotating bearing ring facing each other. A plurality of balls, each made of steel, provided with a contact angle between the stationary-side track and the rotating-side track existing on the circumferential surface, and the diameters of these balls and these The ratio with the pitch circle diameter of each ball is regulated within the range of 0.12-0.4,
The load measuring device includes an encoder that is supported concentrically with the rotation-side raceway on a part of the rotation-side raceway, and in which the characteristics of the surface to be detected are alternately changed with respect to the circumferential direction, and a detection unit thereof. A sensor that is supported by a portion that does not rotate in a state of being opposed to the detection surface and changes its output signal in response to a change in the characteristics of the detection surface, and based on the output signal of the sensor, And a calculator for calculating a load acting between the rotating side raceway and the rotating side raceway,
The pitch or phase at which the characteristics of the detected surface change with respect to the circumferential direction is continuous with respect to the width direction of the detected surface, which coincides with the direction in which the two races are displaced corresponding to the action of the load to be detected. Is changing,
Ball bearing unit with load measuring device.   On the detection surface of the encoder, the first detection portion and the second detection portion having different characteristics are alternately arranged at equal intervals in the circumferential direction, and the circumferential direction of these detection portions is related to the circumferential direction. Of the widths, the width of the first detected portion is wider on one side in the width direction of the detected surface, the width of the second detected portion is wider on the other side in the width direction of the detected surface, and the output signal of the sensor is , A pulse-like signal or a sine wave-like signal that changes a value related to the period or amplitude in accordance with the difference in the width in the circumferential direction between the first detected part and the second detected part. Alternatively, the ball bearing unit with a load measuring device according to claim 6, wherein a load acting between the stationary side raceway and the rotation side raceway is obtained based on a signal representing a ratio related to amplitude.   On the detected surface of the encoder, a plurality of detected combination parts each consisting of a pair of individualized parts having different characteristics from the other parts are arranged at equal intervals in the circumferential direction. The intervals in the circumferential direction between each pair of individualized parts constituting the combination part for detection are continuously changed in the same direction with respect to the width direction of the detected surface in all the combination parts for detection. The phase of the change in the output signal of the sensor changes corresponding to the position in the width direction of the detected surface of the encoder facing the detection unit of the sensor. The ball bearing unit with a load measuring device according to claim 6, wherein a load acting between the stationary side raceway and the rotation side raceway is obtained based on the signal to be expressed.   A pair of sensors installed with the respective detection units positioned at positions separated in the width direction of the detection surface of the encoder are provided, and the detection units of at least one of the detection surfaces are opposed to each other. In the encoder, the boundary where the characteristic changes in the circumferential direction is inclined with respect to the width direction, and the phase of the change in the output signal of the at least one sensor is opposed to the detection unit of the sensor. The calculator changes the load acting between the stationary side raceway and the rotation side raceway based on the signal indicating the phase of this change. The ball bearing unit with a load measuring device according to claim 6 to be obtained.

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