JP2005180985A - Load measuring device for rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the detection of revolving speeds of rolling elements 9a and 9b of both lines even with a narrowed space between the rolling elements 9a and 9b, so that the load applied between an outer ring 1b and a hub 2b can be measured. <P>SOLUTION: In this load measuring device for rolling bearing unit, rotating speed detecting encoders 25c and 25d are set on the mutually opposite side surfaces of retainers 24c and 24d holding the rolling elements 9a and 9b of both lines, respectively, and revolving speed detecting sensors 23c and 23d supported by seal rings 27a and 27b closing both ends of a space 28 in which the rolling elements 9a and 9b of both lines and the retainers 24c and 24d are provided are set so as to be opposed to the surfaces to be detected of both the rotating speed detecting encoders 25c and 25d. According to this structure, it is not necessary to arrange a revolving speed detecting sensor between both the retainers 24c and 24d. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  A load measuring device for a rolling bearing unit that is an object of the present invention is, for example, a load (one or both of a radial load and an axial load) applied to a rolling bearing unit for supporting wheels of a vehicle such as an automobile or a railway vehicle. ) Is measured and used to ensure the running stability of the vehicle.

  For example, an automobile wheel is rotatably supported by a double row angular rolling bearing unit with respect to a suspension device. In order to ensure the running stability of automobiles, vehicle running stabilizers such as an antilock brake system (ABS), a traction control system (TCS), and a vehicle stability control system (VSC) are used. . In order to control such various vehicle running stabilizers, 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. The rolling bearing unit with a load measuring device of the first example of this conventional structure measures a radial load and is configured as shown in FIG. A hub 2 for coupling and fixing the wheel is supported on the inner diameter side of the outer ring 1 supported by the suspension device. The hub 2 has a rotation side flange 3 for fixing the wheel at its outer end (the end on the outer side in the width direction when assembled to the vehicle, the left end in FIGS. 1, 2, 4, 8 to 10). The hub main body 4 and the inner end portion of the hub main body 4 (the end portion on the center side in the width direction when assembled to the vehicle, the right end portion in FIGS. 1, 2, 4, 8 to 10) are externally fitted. And an inner ring 6 held down by a nut 5. A plurality of rolling rings are provided between the double row outer ring raceways 7 and 7 formed on the inner peripheral surface of the outer ring 1 and the double row inner ring raceways 8 and 8 formed on the outer peripheral surface of the hub 2. The moving bodies 9a and 9b are arranged to freely rotate the hub 2 on the inner diameter side of the outer ring 1.

  A mounting hole 10 that diametrically penetrates the outer ring 1 is formed in a substantially vertical direction at an upper end portion of the outer ring 1 in a portion between the double row outer ring raceways 7 and 7 at an intermediate portion in the axial direction of the outer ring 1. Yes. In the mounting hole 10, a circular rod-shaped (round bar-shaped) displacement sensor 11, which is a load measuring sensor, is mounted. This displacement sensor 11 is a non-contact type, and the detection surface provided on the front end surface (lower end surface) is closely opposed to the outer peripheral surface of the sensor ring 12 fitted and fixed to the intermediate portion in the axial direction of the hub 2. When the distance between the detection surface and the outer peripheral surface of the sensor ring 12 changes, the displacement sensor 11 outputs a signal corresponding to the amount of change.

  In the case of the conventional rolling bearing unit with a load measuring device configured as described above, the load applied to the rolling bearing unit can be obtained based on the detection signal of the displacement sensor 11. That is, the outer ring 1 supported by the vehicle suspension device is pushed downward by the weight of the vehicle, whereas the hub 2 supporting and fixing the wheel tends to stop at the same position. For this reason, the greater the weight, the greater the deviation between the center of the outer ring 1 and the center of the hub 2 based on the elastic deformation of the outer ring 1, the hub 2, and the rolling elements 9a, 9b. The distance between the detection surface of the displacement sensor 11 and the outer peripheral surface of the sensor ring 12 provided at the upper end of the outer ring 1 becomes shorter as the weight increases. Therefore, if the detection signal of the displacement sensor 11 is sent to the controller, the radial load applied to the rolling bearing unit in which the displacement sensor 11 is incorporated can be obtained from a relational expression or a map obtained beforehand through experiments or the like. Based on the load applied to each rolling bearing unit thus obtained, the ABS is appropriately controlled and the driver is informed of the poor loading state.

  In the conventional structure shown in FIG. 8, the rotational speed of the hub 2 can be detected in addition to the load applied to the rolling bearing unit. For this purpose, the rotational speed detecting encoder 13 is fitted and fixed to the inner end of the inner ring 6, and the rotational speed detecting sensor 15 is supported on the cover 14 attached to the inner end opening of the outer ring 1. Yes. And the detection part of this rotational speed detection sensor 15 is made to oppose the to-be-detected part of the said encoder 13 for rotational speed detection through the measurement clearance gap.

  When the rolling bearing unit incorporating the rotational speed detecting device as described above is used, the rotational speed detecting encoder 13 is rotated together with the hub 2 to which the wheel is fixed, and the detected portion of the rotational speed detecting encoder 13 is rotated as described above. When traveling in the vicinity of the detection unit of the speed detection sensor 15, the output of the rotation speed detection sensor 15 changes. The frequency at which the output of the rotational speed detection sensor 15 changes in this way is proportional to the rotational speed of the wheel. Therefore, if the output signal of the rotational speed detection sensor 15 is sent to a controller (not shown), ABS and TCS can be controlled appropriately.

  The rolling bearing unit with a load measuring device of the first example of the conventional structure as described above is for measuring the radial load applied to the rolling bearing unit, but the structure for measuring the axial load applied to the rolling bearing unit is also, It is described in Patent Document 2 and the like and has been conventionally known. FIG. 9 shows a rolling bearing unit with a load measuring device for measuring an axial load described in Patent Document 2. As shown in FIG. In the case of the second example of this conventional structure, the rotation side flange 3a for supporting the wheel is fixed on the outer peripheral surface of the outer end portion of the hub 2a. A fixed-side flange 17 is fixed to the outer peripheral surface of the outer ring 1a for supporting and fixing the outer ring 1a to a knuckle 16 constituting a suspension device. A plurality of rolling rings are respectively provided between the double row outer ring raceways 7 and 7 formed on the inner peripheral surface of the outer ring 1a and the double row inner ring raceways 8 and 8 formed on the outer peripheral surface of the hub 2a. By providing the moving bodies 9a and 9b so as to be able to roll, the hub 2a is rotatably supported on the inner diameter side of the outer ring 1a.

  Further, a load sensor 20 is attached to a part surrounding the screw hole 19 for screwing the bolt 18 for connecting the fixed side flange 17 to the knuckle 16 at a plurality of positions on the inner side surface of the fixed side flange 17. Has been established. Each load sensor 20 is sandwiched between the outer side surface of the knuckle 16 and the inner side surface of the fixed-side flange 17 in a state where the outer ring 1 a is supported and fixed to the knuckle 16.

  In the case of the load measuring device of the rolling bearing unit of the second example having such a conventional structure, when an axial load is applied between a wheel (not shown) and the knuckle 16, the outer surface of the knuckle 16 and the fixed side flange 17 The inner surface strongly presses the load sensors 20 from both sides in the axial direction. Therefore, the axial load applied between the wheel and the knuckle 16 can be obtained by summing up the measured values of the load sensors 20. Although not shown, Patent Document 3 describes a method of obtaining the revolution speed of the rolling element from the vibration frequency of a member corresponding to an outer ring having a reduced rigidity, and measuring the axial load applied to the rolling bearing. ing.

  In the case of the first example of the conventional structure shown in FIG. 8 described above, the radial load applied to the rolling bearing unit is measured by measuring the displacement in the radial direction between the outer ring 1 and the hub 2 by the displacement sensor 11. However, since the amount of displacement in the radial direction is small, it is necessary to use a highly accurate displacement sensor 11 in order to obtain the radial 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 case of the second example of the conventional structure shown in FIG. 9 described above, it is necessary to provide as many load sensors 20 as the number of bolts 18 for supporting and fixing the outer ring 1a to the knuckle 16. For this reason, coupled with the fact that the load sensor 20 itself is expensive, it is inevitable that the cost of the entire load measuring device of the rolling bearing unit is considerably increased. Further, the method described in Patent Document 3 requires that the rigidity of a part of the outer ring equivalent member be lowered, and it may be difficult to ensure the durability of the outer ring equivalent member. Further, since the revolution speed of the rolling element is obtained from the vibration frequency of the outer ring equivalent member, there is a problem that the revolution speed cannot be measured accurately.

  In view of such circumstances, the present inventors have previously described this rolling bearing unit based on the revolution speed of a pair of rolling elements (balls) constituting a rolling bearing unit which is a double row angular ball bearing. An invention relating to a load measuring device for a rolling bearing unit that measures a radial load or an axial load applied to the bearing is performed (Japanese Patent Application Nos. 2003-171715 and 172483). FIG. 10 shows a load measuring device for a rolling bearing unit according to the present invention. In the case of the structure according to the previous invention, the sensor unit 21 is inserted into the mounting hole 10a formed in the portion between the double-row outer ring raceways 7 and 7 at the intermediate portion in the axial direction of the outer ring 1 which is an outer ring equivalent member. The front end portion 22 of the outer ring 1 protrudes from the inner peripheral surface of the outer ring 1. The tip portion 22 is provided with a pair of revolution speed detection sensors 23a and 23b and one rotational speed detection sensor 15a.

  And the detection part of each revolution speed detection sensor 23a, 23b of these is provided in each retainer 24a, 24b which hold | maintained each rolling element 9a, 9b arrange | positioned in a double row freely, The revolution speed detection The revolving speeds of the rolling elements 9a and 9b are made freely detectable by being close to and facing the encoders 25a and 25b. Further, the rotational speed of the hub 2 can be detected by making the detection part of the rotational speed detection sensor 15a close to and opposed to the rotational speed detection encoder 13a externally fitted and fixed to the intermediate part of the hub 2 which is an inner ring equivalent member. It is said. According to the load measuring device for a rolling bearing unit according to the prior invention having such a configuration, a load (one or both of a radial load and an axial load) applied between the outer ring 1 and the hub 2 is obtained. It is done.

That is, in the case of the load measuring device for a rolling bearing unit according to the above-described prior invention, an arithmetic unit (not shown) performs the outer ring 1 and the hub 2 based on the detection signals sent from the sensors 23a, 23b, 15a. One or both of a radial load and an axial load applied between the two are calculated. For example, when the radial load is obtained, the computing unit obtains the sum of the revolution speeds of the rolling elements 9a and 9b in each row detected by the revolution speed detection sensors 23a and 23b, and the sum and the rotation speed. The radial load is calculated based on the ratio to the rotational speed of the hub 2 detected by the detection sensor 15a. Further, the axial load is obtained by calculating the difference between the revolution speeds of the rolling elements 9a and 9b in each row detected by the revolution speed detection sensors 23a and 23b, and this difference and the rotational speed detection sensor 15a are detected. Calculation is based on the ratio to the rotational speed of the hub 2. This point will be described with reference to FIG. In the following description, it is assumed that the contact angles α _a and α _b of the rolling elements 9 a and 9 b in the respective rows are the same in a state where the axial load Fy is not applied.

FIG. 11 schematically shows the wheel bearing rolling bearing unit shown in FIG. 10 described above and shows the action state of the load. Preloads F ₀ and F ₀ are applied to the rolling elements 9 a and 9 b arranged in a double row between the double row inner ring raceways 8 and 8 and the double row outer ring raceways 7 and 7. Further, a radial load Fz is applied to the rolling bearing unit during use due to the weight of the vehicle body or the like. Further, an axial load Fy is applied due to centrifugal force applied during turning. These preloads F ₀ , F ₀ , radial load Fz, and axial load Fy all affect the contact angles α (α _a , α _b ) of the rolling elements 9a, 9b. Then, the contact angle alpha _a, the alpha _b is changed, these rolling elements 9a, the revolution speed n _c of 9b changes. The diameter of the pitch circle of each of these rolling elements 9a, 9b is D, the diameter of each of these rolling elements 9a, 9b is d, the rotational speed of the hub 2 provided with each of the inner ring raceways 8, 8 is n _i , When the rotational speed of the outer race 1 provided with the outer ring raceway 7, 7 and n _o, the revolution speed n _c is expressed by the following equation.
n _c = {1− (d · cos α / D) · (n _i / 2)} + {1+ (d · cos α / D) · (n _o / 2)}

As is evident from this equation, the rolling elements 9a, revolution speed n _c of 9b, these rolling elements 9a, the contact angle α (α _a, α _b) of 9b varies in response to changes in, the above-described Similarly, the contact angles α _a and α _b vary according to the radial load Fz and the axial load Fy. Thus the revolution speed n _c is changed according to these radial load Fz and the axial load Fy. In this example, the hub 2 is rotated, since the outer ring 1 is not rotated, specifically, with respect to the radial load Fz, the revolution speed n _c is slow enough to increase. Further, with respect to the axial load Fy, the revolution speed of the row that supports the axial load Fy is increased, and the revolution speed of the row that does not support the axial load Fy is decreased. Therefore, on the basis of the revolution speed n _c, it will be asked to the radial load Fz and the axial load Fy.

However, the revolution speed n _c the contact angle α (α _a, α _b) which leads to changes in not only the radial load Fz and the said axial load Fy changes while associated with each other, the preload F _0, also it changes by the F _0. Also, the revolution speed n _c is changed in proportion to the rotational speed n _i of the hub 2. Therefore, these radial load Fz, axial load Fy, the preload F _0, F _0, to be considered in conjunction all the rotational speed n _i of the hub 2, it is impossible to correctly determine the revolution speed n _c. Of these, the preloads F ₀ and F ₀ do not change according to the operating state, so it is easy to eliminate the influence by initial setting or the like. The radial load Fz with respect to this, the axial load Fy, the rotational speed n _i of the hub 2, since the constantly changing depending on the operating conditions, it is impossible to eliminate the influence by such initialization.

In view of such circumstances, in the prior invention, as described above, when the radial load Fz is obtained, the revolution speeds of the rolling elements 9a and 9b in the respective rows detected by the revolution speed detection sensors 23a and 23b are detected. The influence of the axial load Fy is reduced. Further, when the axial load Fy is obtained, the influence of the radial load Fz is reduced by obtaining the difference between the revolution speeds of the rolling elements 9a and 9b in each row. Furthermore, in any case, possible to calculate the radial load Fz or the axial load Fy on the basis of the ratio of the above sum or difference, the rotational speed detecting sensor 15a is a rotational speed n _i of the hub 2 for detecting way, by eliminating the influence of the rotational speed n _i of the hub 2. However, the axial load Fy, when calculating on the basis of the rolling elements 9a, 9b ratio of the revolution speed of said each row, the rotational speed n _i of the hub 2 is not necessarily required.

  There are various other methods for calculating one or both of the radial load Fz and the axial load Fy based on the signals of the revolution speed detection sensors 23a and 23b. Such a method is described in detail in the above-mentioned Japanese Patent Application Nos. 2003-171715 and 172483, and is not related to the gist of the present invention, and thus detailed description thereof is omitted.

  In the case of the structure according to the above-described prior invention, the sensor unit 21 is inserted into the mounting hole 10a formed in the portion between the pair of outer ring raceways 7 and 7 at the intermediate portion in the axial direction of the outer ring 1, and the tip of the sensor unit 21 is inserted. 22 protrudes from the inner peripheral surface of the outer ring 1. For this reason, when the distance (axial pitch) between the pair of outer ring raceways 7 and 7 is short, such as a rolling bearing unit for supporting a wheel of a small automobile, the mounting hole 10a is formed, and the sensor unit is further formed. It becomes difficult to protrude the tip portion 22 of 21 from the inner peripheral surface of the outer ring 1. Further, even if the tip 22 is protruded from the inner peripheral surface of the outer ring 1, it is inevitable that the strength and rigidity of the outer ring 1 are reduced by the amount of the mounting hole 10a. Such a decrease in strength and rigidity can be dealt with by increasing the thickness of the outer ring 1, but the weight of the outer ring 1 increases accordingly. Since the rolling bearing unit for supporting the wheel including the outer ring 1 is a so-called unsprung load that exists on the road surface side of the spring incorporated in the suspension device, a slight increase in weight is centered on running stability. This is not preferable because it adversely affects running performance.

JP 2001-21577 A Japanese Patent Laid-Open No. 3-209016 Japanese Patent Publication No.62-3365

  In view of the circumstances as described above, the present invention can be implemented even with a small-sized rolling bearing unit having a short interval between outer ring raceways, and does not reduce the strength and rigidity of the outer ring. Invented to realize the above.

The load measuring device of the rolling bearing unit of the present invention includes an outer ring equivalent member, an inner ring equivalent member, a plurality of rolling elements, a cage, a seal ring, a revolution speed detection encoder, a revolution speed detection sensor, And an arithmetic unit.
Of these, the outer ring equivalent member has an outer ring raceway on the inner peripheral surface.
The inner ring equivalent member is disposed concentrically with the outer ring equivalent member on the inner diameter side of the outer ring equivalent member, and has an inner ring raceway on the outer peripheral surface.
Each of the rolling elements is provided with a contact angle between the inner ring raceway and the outer ring raceway.
Moreover, the said holder | retainer hold | maintains each said rolling element so that rolling is possible.
The seal ring closes an end opening of the space where the rolling elements are installed between the inner peripheral surface of the outer ring equivalent member and the outer peripheral surface of the inner ring equivalent member.
The revolution speed detecting encoder is provided over the entire circumference in a part of the cage facing the seal ring, and the characteristics of the surface to be detected are alternately changed in the circumferential direction. It is changed at equal intervals.
The revolution speed detection sensor is provided in a part of the seal ring facing the revolution speed detection encoder, and detects the rotational speed of the cage, which is the revolution speed of each rolling element.
Further, the computing unit calculates a load applied between the outer ring equivalent member and the inner ring equivalent member based on a detection signal sent from the revolution speed detection sensor and representing the revolution speed of each rolling element. .

The load measuring device of the rolling bearing unit of the present invention configured as described above can measure the load applied to the rolling bearing unit by detecting the revolution speed of the rolling element. That is, when a load is applied to a rolling bearing unit such as a ball bearing, the contact angle of the rolling elements (balls) changes, and the revolution speed of each rolling element changes. Therefore, if this revolution speed is detected, a load acting between the outer ring equivalent member and the inner ring equivalent member can be obtained.
Furthermore, according to the load measuring device of the rolling bearing unit of the present invention, it is not necessary to form a through hole such as a mounting hole in the outer ring equivalent member in order to install the revolution speed detecting sensor. For this reason, even a small rolling bearing unit with a short interval between outer ring raceways can be implemented, and the strength and rigidity of the outer ring equivalent member can be secured without increasing the thickness of the outer ring equivalent member. For this reason, it is easy to improve the performance centering on the running stability of the vehicle equipped with the load measuring device of the rolling bearing unit.

Preferably, when carrying out the present invention, preferably, as described in claim 2, a double-row outer ring raceway provided on the inner peripheral surface of the outer ring equivalent member and a double-row inner ring provided on the outer peripheral surface of the inner ring equivalent member A plurality of rolling elements are provided in two rows between the tracks, with the contact angles being reversed between each other, and the rolling elements are rolled by a pair of cages. Hold freely. A pair of revolution speed detection encoders are provided on the opposite side surfaces of the two cages, and supported by the opposite side surfaces of the pair of seal rings that close the openings at both ends of the space where the rolling elements are installed. The detection units of the pair of revolution speed detection sensors are respectively opposed to the detected surfaces of the both revolution speed detection encoders.
If comprised in this way, it will become possible to obtain | require correctly the load added to a highly rigid rolling bearing unit.

Preferably, as described in claim 3, a revolving speed detection encoder made of a permanent magnet having S poles and N poles alternately arranged at equal intervals in the circumferential direction on the surface to be detected is used. To do.
If comprised in this way, the structure of the revolution speed detection sensor will be simplified, and this revolution speed detection sensor will be easily mounted on the seal ring.
In this way, when an encoder made of a permanent magnet is used as the revolution speed detection encoder, for example, as described in claim 4, an active type magnetic sensor having a magnetic detection element is used as the revolution speed detection sensor. use.
Since such an active magnetic sensor can be configured to be small and light, it can be supported sufficiently reliably with respect to the seal ring.

Alternatively, as described in claim 5, a frequency generator (FG) provided over the entire circumference of the seal ring is used as the revolution speed detecting sensor.
The frequency generator is opposed to the detected surface of the revolution speed detection encoder over the entire circumference, and changes the output in accordance with the rotation of the revolution speed detection encoder. That is, the output of the revolution speed detection sensor, which is a frequency generator, changes based on the average characteristic change over the entire circumference of the detected surface of the revolution speed detection encoder. Therefore, even if there is an error in the pitch between the south pole and the north pole provided on the detection surface of the revolution speed detection encoder made of permanent magnet, this error is an error in the output change of the revolution speed detection sensor. There is no direct connection to. For this reason, regardless of the pitch error of the characteristic change of the surface to be detected of the encoder for detecting the revolution speed made of the permanent magnet, it acts between the revolution speed of each rolling element, and thus between the outer ring equivalent member and the inner ring equivalent member. The load can be calculated accurately.
In addition, since the revolution speed detection sensor can have a function as a generator, the signal processing circuit or the like attached to the revolution speed detection sensor can be driven without an external power source. For this reason, the conductor for supplying power to the signal processing circuit can be omitted and the number of conductors can be reduced, and the detection signal of the revolution speed detection sensor can be transmitted to the vehicle body side without preparing another power source such as a battery. It can also be sent wirelessly to the controller provided.

When the present invention is implemented, preferably, as described in claim 6, the wheel is rotatably supported by the suspension device, and the load applied to the wheel is measured.
If comprised in this way, it will become possible to perform a high degree control in order to ensure running stability of a car.

  1 to 3 show Embodiment 1 of the present invention corresponding to claims 1 to 4 and 6. This embodiment is applied when the present invention is applied to a rolling bearing unit for supporting driving wheels of an automobile (FR wheel, RR wheel, rear wheel of MR vehicle, front wheel of FF vehicle, all wheels of 4WD vehicle). It shows. The hub 2b, which is an inner ring equivalent member, is formed by fitting the inner ring 6 to the inner end of the hub body 4a. The rotation side flange 3b for supporting a wheel is fixed to the outer peripheral surface of the outer end portion of the hub body 4a. In addition, by forming inner ring raceways 8 and 8 on the outer peripheral surface of the intermediate portion of the hub body 4a and the outer peripheral surface of the inner ring 6, respectively, the double-row angular inner ring raceways 8 and 8 are formed on the outer peripheral surface of the hub 2b. Is provided.

  On the other hand, the outer ring 1b is supported and fixed to the knuckle 16 (see FIG. 9) constituting the suspension device on the outer peripheral surface of the outer ring 1b, which is a member corresponding to the outer ring, arranged around the hub 2b and concentrically with the hub 2b. For this purpose, a fixed flange 17a is fixed. Further, double row angular outer ring raceways 7 are formed on the inner peripheral surface of the outer ring 1b. And, by providing a plurality of rolling elements (balls) 9a, 9b separately between the outer ring raceways 7, 7 and the inner ring raceways 8, 8, respectively, in a double row so as to be freely rollable. The hub 2b is rotatably supported on the inner diameter side of the outer ring 1b. The rolling elements 9a and 9b are held by the cages 24c and 24d so as to be freely rollable. In the case of the present embodiment, the cages 24c and 24d are machined with rim portions 26a and 26b at both axial ends, but the rim portions are provided only at one axial end. A crown-shaped cage can also be used. However, when using a crown-shaped cage, the rim portions of the pair of cages are directed to opposite sides (the rim portions of both cages are opposed to seal rings 27a and 27b described below).

  Between the inner peripheral surface of the outer ring 1b and the outer peripheral surface of the hub 2b, both end openings of the space 28 in which the rolling elements 9a and 9b and the retainers 24c and 24d are installed are respectively sealed rings 27a, It is blocked by 27b. These seal rings 27a and 27b are each formed by combining a cored bar formed in an annular shape and an elastic material such as an elastomer such as rubber. The outer peripheral edges of the seal rings 27a and 27b are the inner peripheral surface of the outer ring 1b. It is locked over the entire circumference in the locking groove formed in the above. In this state, seal lips formed on the inner peripheral edge portions of the seal rings 27a and 27b are brought into sliding contact with the surface of the hub 2b over the entire circumference. A combined seal ring can also be used as the seal ring. In this case, the slinger constituting the combination seal ring is fitted and fixed to the hub, and the seal lip is brought into sliding contact with the slinger over the entire circumference.

  In the case of this embodiment, among the cages 24c and 24d, the rim portions 26a and 26a facing the seal rings 27a and 27b are respectively provided with revolution speed detecting encoders 25c and 25d on the side surfaces over the entire circumference. Are supported and fixed. These revolving speed detection encoders 25c and 25d are made of permanent magnets and are magnetized in the axial direction. The magnetization direction is changed alternately and at equal intervals in the circumferential direction. Therefore, as shown in FIG. 3, S poles and N poles are alternately arranged at equal intervals on the side surfaces in the axial direction of the two revolution speed detecting encoders 25c and 25d, which are detected surfaces. The permanent magnets constituting both the revolving speed detecting encoders 25c and 25d may be rubber magnets or plastic magnets mixed with powder of a magnetic material such as ferrite or neodymium, or ferrite magnets or rare earth magnets. In short, it is only necessary that the permanent magnets in which the S poles and the N poles are alternately arranged at equal intervals in the circumferential direction can be supported by the rim portions 26a and 26a of the cages 24c and 24d over the entire circumference. . Further, the rim portions 26a, 26a and the permanent magnet may be integrally formed.

  Revolution speed detection sensors 23c and 23d are supported and fixed on the side surfaces of the seal rings 27a and 27b facing the revolution speed detection encoders 25c and 25d, respectively. These revolving speed detection sensors 23c and 23d use an active type magnetic sensor provided with a magnetic detection element that changes its characteristics by a magnetic change, such as a Hall element, Hall IC, magnetoresistive element, MR element or the like. ing. The two revolution speed detection sensors 23c and 23d and the two revolution speed detection encoders 25c and 25d do not necessarily have to face each other in the axial direction as shown in the drawing, and can face each other in the radial direction. In this case, S poles and N poles are alternately arranged at equal intervals in the circumferential direction on the circumferential surfaces of the two revolution speed detecting encoders 25c and 25d.

  When the rolling bearing unit as described above is used, a spline shaft attached to a constant velocity joint (not shown) is inserted into a spline hole 29 formed in the central portion of the hub body 4a. The hub 2b is clamped from both sides in the axial direction between a nut screwed to the tip of the spline shaft and a housing of the constant velocity joint. The fixed flange 17a is supported and fixed to the knuckle 16 by a plurality of bolts. Further, a braking disk and a wheel of the wheel are supported and fixed to the rotation side flange 3b by a plurality of studs 30 and nuts (not shown).

  In this state, when a load is applied between the outer ring 1b and the hub 2b during traveling, the rotational speed of the cages 24c and 24d, which is the revolution speed of the rolling elements 9a and 9b in each row, changes. . The rotational speeds of the two cages 24c and 24d are detected by the two revolution speed detection sensors 23c and 23d and sent to a controller having a computing unit (not shown). This computing unit stores the empirical formula stored in advance. Alternatively, the load (one or both of the radial load and the axial load) is obtained based on the map. As described above, the processing for obtaining the load based on the revolution speeds of the rolling elements 9a and 9b in both rows is the same as in the case of the above-described prior invention, and therefore, duplicate description is omitted.

  When the axial load is calculated based on the ratio of the revolution speeds of the rolling elements 9a and 9b in both rows, the rotational speed of the hub 2b is not necessarily required. Therefore, the axial load can be obtained only by signals from the two revolution speed detection sensors 23c and 23d. However, in order to improve the measurement accuracy of the radial load and the axial load, it is free to add a rotation speed sensor for obtaining the rotation speed of the hub 2b. The rotational speed sensor used in this case may be one that has been conventionally used for controlling ABS. In any case, both the revolving speed detection encoders 25c and 25d are disposed on opposite sides of the retainers 24c and 24d, and both the revolving speed detection sensors 23c and 23d are disposed on the side surfaces of the seal rings 27a and 27b. In addition, by arranging each of them, even when the space between the rolling elements 9a, 9b in both rows is narrow, the revolution speed of the rolling elements 9a, 9b in both rows can be detected. Note that the calculator that calculates the load based on the detection signal of each sensor may be provided in the rolling bearing unit, or may be provided in a portion other than the rolling bearing unit, such as the vehicle body side.

  4 to 5 show a second embodiment of the present invention corresponding to claims 1 to 3, 5 and 6. In the case of the present embodiment, an annular frequency generator (FG) is used as both revolution speed detecting sensors 23e, 23f supported and fixed to the side surfaces of both seal rings 27a, 27b. While such a frequency generator is used for the two revolution speed detection sensors 23e and 23f, it is supported and fixed to the opposite sides of the two cages 24c and 24d holding the rolling elements 9a and 9b in both rows. The two revolution speed detecting encoders 25c and 25d are arranged with S poles and N poles alternately and at equal intervals on the side surface in the axial direction, as shown in FIG. 3, as in the first embodiment. I am using something.

  The two revolution speed detection sensors 23e and 23f for detecting the rotational speeds of the cages 24c and 24d in combination with the both revolution speed detection encoders 25c and 25d, as shown in FIG. It is formed in a closed ring shape having substantially the same diameter as the speed detection encoders 25c and 25d. A coil 31 is wound around the revolving speed detection sensors 23e and 23f. This coil 31 is present on the detected surface of both the revolution speed detecting encoders 25c and 25d when the both revolution speed detecting encoders 25c and 25d and the both revolution speed detecting sensors 23e and 23f are relatively rotated. The radial portions 32 and 32 arranged so as to cross and move the magnetic flux flowing from the pole to the south pole are alternately continued by the circumferential portions 33a and 33b existing on the inner diameter side and the outer diameter side, respectively. The shape meanders in the circumferential direction.

  The number of the radial portions 32 and 32 is equal to the number of boundaries between the N pole and the S pole existing on the detected surfaces of the two revolution speed detecting encoders 25c and 25d. The radial portions 32 and 32 are arranged at equal intervals in the circumferential direction. Accordingly, when the two revolution speed detection encoders 25c and 25d and the two revolution speed detection sensors 23e and 23f are rotated relative to each other, the radial portions 32 and 32 simultaneously apply to the magnetic flux flowing from the N pole to the S pole. Intersect. When the coil 31 is configured, the conductive wire may be attached to a substrate made of an insulating material, or may be formed on the substrate by etching or the like. Furthermore, the core metal constituting both the seal rings 27a and 27b may be an iron substrate, and the coil 31 may be directly formed on the iron substrate. In addition, it is preferable to make the core metal which comprises the said both seal rings 27a and 27b into a non-magnetic body except the case where the core metal made from an iron substrate is used. The reason for this is to reduce the heat generation based on the eddy current generated by the alternating magnetic field based on the rotation of the both revolution speed detecting encoders 25c and 25d. Particularly preferably, the core material that reinforces the elastic material constituting both the seal rings 27a and 27b is made of a material that does not cause eddy current loss such as synthetic resin.

  In the case of the present embodiment having the above-described configuration, when both the revolving speed detecting encoders 25c and 25d rotate together with the two retainers 24c and 24d holding the rolling elements 9a and 9b in both rows, the both revolving speeds are obtained. The magnetic flux emitted from the detection surfaces of the detection encoders 25c and 25d generates an alternating magnetic field in the coil 31 portions of the two revolution speed detection sensors 23e and 23f. As a result, a voltage (alternating current) changing in a sine wave shape is induced in the coil 31. The frequency at which the voltage induced in the coil 31 changes in this way is proportional to the rotational speeds of the two revolution speed detection encoders 25c and 25d. From this frequency, the rolling elements 9a and 9b in both rows are Revolution speed is required.

  In the case of the present embodiment, as described above, both the revolution speed detection sensors 23e and 23f are opposed to the detection surfaces of the both revolution speed detection encoders 25c and 25d over the entire circumference. As a frequency generator. For this reason, the voltage induced in the coil 31 is the entire circumference (integral value of the entire circumference), the output voltages of the detection signals of the two revolution speed detection sensors 23e and 23f are increased, and the processing of the detection signals is performed. It becomes easy. Further, the influence of the pitch error between the N pole and the S pole existing on the detected surfaces of the both revolution speed detecting encoders 25c and 25d can be reduced, and the accuracy of the revolution speed detection is improved.

  If the voltage generated in the coil 31 is rectified and used as electric power, the signal processing circuits attached to the two revolution speed detection sensors 23e and 23f can be driven without an external power source. For this reason, the conductors for supplying power to the signal processing circuit can be omitted to reduce the number of conductors, and the detection signals of the revolving speed detection sensors 23e and 23f can be obtained without preparing other power sources such as batteries. Can be wirelessly sent to a controller equipped with a computing unit. With this configuration, even when the revolution speed detection sensors 23e and 23f need to be frequently attached / detached, it is not necessary to attach / detach a cable for sending electric power or signals each time. Man-hours required for attaching and detaching the detection sensors 23e and 23f can be reduced. In this case, when the electromotive force induced in the coil 31 is small, the coils may be provided in multiple layers in order to increase the power generation amount. Further, the power generation in the coil 31 portion is not sufficiently performed unless the rotational speeds of the two revolution speed detecting encoders 25c and 25d are increased to a certain degree or more. When it is necessary to supply power to a circuit or the like, it is preferable to mount a battery such as a secondary battery. Other configurations and operations are the same as those of the first embodiment described above, and thus redundant description is omitted.

  FIGS. 6-7 has shown Example 3 of this invention corresponding to Claims 1-3, 5, 6 of embodiment of this invention. In this embodiment, the revolution speed detecting encoders 25e and 25f are made of permanent magnets magnetized in the radial direction. The magnetization direction is changed alternately and at equal intervals in the circumferential direction. Therefore, as shown in FIG. 6, S poles and N poles are alternately arranged at equal intervals on the outer peripheral surfaces of the two revolution speed detection encoders 25e and 25f, which are detected surfaces. In accordance with this, the revolution speed detection sensors 23g and 23h are provided with a coil 31a on the inner peripheral surface. The inner diameters of the two revolution speed detection sensors 23g and 23h are slightly larger than the outer diameters of the two revolution speed detection encoders 25e and 25f, and the coil 31a is arranged on the outer circumference of the two revolution speed detection encoders 25e and 25f. It is made to oppose to a surface through a detection gap. Other configurations and operations are the same as those of the above-described second embodiment, and thus redundant description is omitted.

Sectional drawing which shows Example 1 of this invention. The A section enlarged view of FIG. The figure which looked at the revolution speed detection encoder from the axial direction. Sectional drawing which shows Example 2 of this invention. The figure which looked at the frequency generator which is a revolution speed detection sensor used for Example 2 from the axial direction. The other example of the revolution speed detection encoder is shown, (A) is seen from an axial direction, (B) is the figure seen from the outer-diameter side, respectively. The other example of a frequency generator is shown, (A) is the figure seen from the axial direction, (B) is seen from the inner diameter side, respectively. Sectional drawing of the rolling bearing unit which incorporated the sensor for radial load measurement known conventionally. Sectional drawing of the rolling bearing unit which incorporated the sensor for axial load measurement conventionally known. Sectional drawing of the load measuring apparatus of the rolling bearing unit which concerns on a prior invention. The schematic diagram for demonstrating the reason for which the load added to a rolling bearing unit is calculated | required.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b Outer ring 2, 2a, 2b Hub 3, 3a, 3b Rotation side flange 4, 4a Hub body 5 Nut 6 Inner ring 7 Outer ring raceway 8 Inner ring raceway 9a, 9b Rolling element 10, 10a Mounting hole 11 Displacement sensor 12 Sensor Ring 13, 13a Rotation speed detection encoder 14 Cover 15, 15a Rotation speed detection sensor 16 Knuckle 17, 17a Fixed flange 18 Bolt 19 Screw hole 20 Load sensor 21 Sensor unit 22 Tip 23a, 23b, 23c, 23d, 23e , 23f, 23g, 23h Revolution speed detection sensor 24a, 24b, 24c, 24d Retainer 25a, 25b, 25c, 25d, 25e, 25f Revolution speed detection encoder 26a, 26b Rim part 27a, 27b Seal ring 28 Space 29 Spline Hole 30 stud 1,31a coil 32 radial portion 33a, 33b circumferential portion

Claims (6)

  An outer ring equivalent member having an outer ring raceway on the inner peripheral surface, an inner ring equivalent member having an inner ring raceway on the outer peripheral surface disposed concentrically with the outer ring equivalent member on the inner diameter side of the outer ring equivalent member, the inner ring raceway and the outer ring A plurality of rolling elements provided with a contact angle between them and the raceway, a cage that holds each of the rolling elements in a freely rolling manner, an inner peripheral surface of the outer ring equivalent member, and an inner ring equivalent A seal ring that closes the end opening of the space in which each of the rolling elements is installed between the outer peripheral surface of the member, and a part of the cage that is provided over the entire circumference in a portion that faces the seal ring. A revolution speed detecting encoder in which the characteristics of the surface to be detected are changed alternately and at equal intervals in the circumferential direction, and a part of the seal ring is provided at a portion facing the revolution speed detecting encoder, The above cage which is the revolution speed of the rolling element Based on a revolution speed detection sensor for detecting the rotation speed and a detection signal sent from the revolution speed detection sensor and representing the revolution speed of each rolling element, between the outer ring equivalent member and the inner ring equivalent member. A load measuring device for a rolling bearing unit comprising an arithmetic unit for calculating an applied load.   A plurality of outer ring raceways provided on the inner peripheral surface of the outer ring equivalent member, a plurality of inner ring raceways provided on the outer peripheral surface of the inner ring equivalent member, and a plurality of each between the outer ring raceways and the inner ring raceways. Each of the rolling elements provided in two rows with the contact angles reversed between each other, a pair of cages that hold each of these rolling elements in a freely rolling manner, and both of these holdings A pair of revolution speed detecting encoders provided on opposite sides of the container, a pair of seal rings for closing the openings at both ends of the space in which the rolling elements are installed, and the opposite sides of these seal rings 2. The load measuring device for a rolling bearing unit according to claim 1, further comprising a pair of revolution speed detection sensors supported by each of the detection parts so as to face the detection surfaces of the two revolution speed detection encoders. .   3. The rolling bearing unit according to claim 1, wherein the revolution speed detecting encoder is a permanent magnet in which S poles and N poles are alternately arranged at equal intervals in the circumferential direction on a detected surface. Load measuring device.   4. The load measuring device for a rolling bearing unit according to claim 3, wherein the revolution speed detection sensor is an active magnetic sensor including a magnetic detection element.   The load measuring device for a rolling bearing unit according to claim 3, wherein the revolution speed detecting sensor is a frequency generator provided over the entire circumference of the seal ring. The load measuring device for a rolling bearing unit according to any one of claims 1 to 5, wherein a wheel is rotatably supported by a suspension device and a load applied to the wheel is measured.

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