JP2005181265A - Load measuring device for rolling bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the detection of revolving speed by both revolving speed detecting sensors 20 and 20b regardless of a change in detection clearance between the detection parts of the revolving speed detecting sensors 20a and 20b and revolving speed detecting encoders 23a and 23b based on an axial load applied in both directions, and to prevent the mutual rubbing between both the revolving speed detecting sensors 20a and 20b and both the revolving speed detecting encoders 23a and 23b. <P>SOLUTION: In this load measuring device for rolling bearing unit, the detection clearance L<SB>A</SB>for the outer line which is narrowed in application of a large axial load is set larger than the detection clearance L<SB>B</SB>for the inner line which is narrowed in application of a small axial load, and the minimum values of both the detection clearances L<SB>A</SB>and L<SB>B</SB>are set equal to each other, so that the width of distribution between both the detection clearances is narrowed. According to this, the setting of both the detection clearances is facilitated to solve the problem. <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 the 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. This hub 2 has a rotating side flange 3 for fixing the wheel at its outer end (outside with respect to the axial direction is the outside in the width direction in the assembled state on the vehicle, FIGS. 1, 2, 4, 5, 6, 7 on the left side, and the inner end of the hub main body 4 (the inner side in the axial direction is the end on the center side in the width direction when assembled to the vehicle. 5, 6, 7) and an inner ring 6 which is externally fitted and 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 radial load applied to the rolling bearing unit can be obtained based on the detection signal of the displacement sensor 11. In the conventional structure shown in FIG. 4, the rotational speed of the hub 2 can be detected in addition to the radial load applied to the rolling bearing unit.

  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. 5 shows a rolling bearing unit with a load measuring device described in Patent Document 2 for measuring an axial load. 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 14 is fixed to the outer peripheral surface of the outer ring 1a for supporting and fixing the outer ring 1a to a knuckle 13 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 17 is attached to a portion surrounding the screw hole 16 for screwing a bolt 15 for connecting the fixed side flange 14 to the knuckle 13 at a plurality of locations on the inner side surface of the fixed side flange 14. Has been established. Each load sensor 17 is sandwiched between the outer side surface of the knuckle 13 and the inner side surface of the fixed flange 14 while the outer ring 1a is supported and fixed to the knuckle 13.

  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 13, the outer surface of the knuckle 13 and the fixed side flange 14 The inner surface strongly presses each load sensor 17 from both sides in the axial direction. Therefore, the axial load applied between the wheel and the knuckle 13 can be obtained by summing up the measured values of the load sensors 17. 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. 4 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. 5 described above, it is necessary to provide the same number of load sensors 17 as the bolts 15 for supporting and fixing the outer ring 1a to the knuckle 13. For this reason, coupled with the fact that the load sensor 17 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. 6 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 18 is inserted into the mounting hole 10a formed in the portion between the double-row outer ring raceways 7 and 7 at the axially intermediate portion of the outer ring 1 which is an outer ring equivalent member and is a stationary ring. The tip 19 of the sensor unit 18 is projected from the inner peripheral surface of the outer ring 1. The distal end portion 19 is provided with a pair of revolution speed detection sensors 20 a and 20 b and a single rotation speed detection sensor 21.

  And the detection part of each revolution speed detection sensor 20a, 20b of these is provided in each retainer 22a, 22b which hold | maintained each rolling element 9a, 9b arrange | positioned in a double row rotatably, The revolution speed detection The revolving speeds of the rolling elements 9a and 9b are made freely detectable by being close to and opposed to the encoders 23a and 23b. Further, the detection portion of the rotation speed detection sensor 21 is made close to and opposed to the rotation speed detection encoder 24 that is an inner ring equivalent member and is externally fitted and fixed to an intermediate portion of the hub 2 that is a rotation wheel. The rotation speed can be detected freely. 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) is configured to output the outer ring 1 and the hub 2 based on detection signals sent from the sensors 20a, 20b, and 21. 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 20a and 20b, 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 21. The axial load is obtained by calculating the difference between the revolution speeds of the rolling elements 9a and 9b in the respective rows detected by the revolution speed detection sensors 20a and 20b, and this difference and the rotation speed detection sensor 21 detect the difference. Calculation is based on the ratio to the rotational speed of the hub 2.

  In the case of the prior invention, when the radial load is obtained, the axial load is obtained by obtaining the sum of the revolution speeds of the rolling elements 9a, 9b detected by the revolution speed detection sensors 20a, 20b. The influence of is reduced. Further, when the axial load is obtained, the influence of the radial load is reduced by obtaining the difference in revolution speed between the rolling elements 9a and 9b in each row. Furthermore, in any case, the hub is calculated by calculating the radial load or the axial load based on a ratio between the sum or difference and the rotational speed of the hub 2 detected by the rotational speed detection sensor 21. 2 is excluded. However, when the axial load is calculated based on the ratio of the revolution speeds of the rolling elements 9a and 9b in each row, the rotational speed of the hub 2 is not necessarily required. However, in order to improve the measurement accuracy, it is free to provide a rotation speed detection sensor for detecting the rotation speed of the hub 2. In this case, a rotational speed sensor conventionally used for ABS control may be used. Furthermore, the arithmetic unit for calculating a load based on the signal from each sensor may be provided in the rolling bearing unit or on the vehicle body side.

  There are various other methods for calculating one or both of the radial load and the axial load based on the signals of the revolution speed detection sensors 20a and 20b. The 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, so detailed description thereof is omitted.

In embodying the structure according to the prior invention as described above, it is necessary to pay attention to the following two points (1) and (2).
(1) Even when one of the revolution speed detection sensors 20a (20b) and the revolution speed detection encoder 23a (23b) comes closest to each other, the revolution speed detection sensor is applied even when the largest axial load considered in use is applied. 20a (20b) and the revolution speed detecting encoder 23a (23b) should not interfere (do not rub).
(2) Similarly, even when the other revolution speed detection sensor 20b (20a) and the revolution speed detection encoder 23b (23a) are farthest away from each other, the revolution speed detection encoder 20b (20a) uses the revolution speed detection sensor 20b (20a). The rotation of 23b (23a) can be reliably detected.

  In consideration of the above (1), it is preferable to increase the axial distance between the two revolution speed detecting sensors 20a, 20b and the two revolution speed detecting encoders 23a, 23b. On the other hand, when the above (2) is considered, it is preferable to reduce the axial distance. Further, when the structure according to the above invention is embodied, it is necessary to make the structure less expensive and less susceptible to the influence of grease existing in the rolling bearing unit. From these aspects, the both revolution speed detecting encoders 23a and 23b are obtained by alternately changing the magnetic characteristics of the detected surface at equal intervals, and the both revolution speed detecting sensors 20a and 20b are used. It is considered preferable to use a device that changes the output in response to the change in the magnetic characteristics.

  When such a magnetic detection type structure is adopted, if the axial distance between the two revolution speed detecting sensors 20a, 20b and the two revolution speed detecting encoders 23a, 23b is increased, the two revolution speed detection is performed. The rotational speed of the encoders 23a and 23b cannot be detected accurately. Specifically, changes in the output signals of the two revolution speed detection sensors 20a and 20b become smaller, or the period of the change is the pitch of the characteristic change of the detected surfaces of the two revolution speed detection encoders 23a and 23b. In other cases, the output signal does not change.

  In the case of the structure of FIG. 6 according to the previous invention, the axial distance between the two revolution speed detection sensors 20a and 20b and the two revolution speed detection encoders 23a and 23b is as follows. Equal to each other. In this way, the axial distances related to the two revolution speed detection sensors 20a and 20b and the two revolution speed detection encoders 23a and 23b are the same, and the above two points (1) and (2) are taken into consideration. When the axial distance between the two revolution speed detection sensors 20a and 20b and the two revolution speed detection encoders 23a and 23b is determined, it is difficult to achieve both low cost and high performance. The reason for this will be described with reference to FIGS. In the following explanation, the load measuring device for the rolling bearing unit shown in FIG. 6 is assembled to the rotation support portion of a wheel (for example, the left front wheel of an FR vehicle) provided on the left side of the vehicle. To do.

When the vehicle is traveling straight on a flat road and no axial load is applied between the outer ring 1 and the hub 2, the two revolution speed detection sensors 20a and 20b and the both revolution speed detection are detected. As shown in FIG. _7A , axial distances (detection gaps) L _a and L _b between the encoders 23a and 23b are substantially equal (excluding errors) (L _a ≈L _b ). . In this case, the biaxial distances L _a and L _b are neutral values (L _a and L _b ) indicated by a straight line α in FIG.

  Next, consider the case where the vehicle turns right (changes to the right). In this case, based on the balance between the centrifugal force applied to the vehicle body and the grip force applied between the wheel and the road surface, the outer wheel 1 supported and fixed on the vehicle body side and the hub 2 supported and fixed to the wheel on the outer side in the turning direction. An axial load is applied in the direction in which the hub 2 is pressed inward in the axial direction (right side in FIG. 6). However, during turning, a load is not uniformly applied to each wheel due to the load movement based on the centrifugal force, but a large load is applied to the wheel located on the outer side in the turning direction. Based on this large load, the grip force of the left wheel located on the outer side in the turning direction becomes larger than the grip force of the right wheel located on the inner side in the turning direction. For this reason, in the case of a rolling bearing unit that supports the left wheel on the outer side in the turning direction, the hub 2 is displaced relatively to the right in FIG. Thus, the axial load applied to the hub 2 that supports and fixes the wheel on the outer side in the turning direction corresponds to the axial load in the direction in which the maximum value described in the claims increases, and the maximum value of this axial load is This is the maximum value of a relatively large axial load. On the other hand, the axial load applied to the hub 2 that supports and fixes the wheel on the inner side in the turning direction corresponds to the axial load in the direction in which the maximum value described in the claims is reduced, and the maximum value of this axial load is The maximum value of the relatively small axial load.

As a result, axial distances (detection gaps) L _a1 and L _b1 between the two revolution speed detection sensors 20a and 20b and the two revolution speed detection encoders 23a and 23b are shown in FIG. As shown in FIG. 8, the value is different from the neutral values (L _a , L _b ). Specifically, with respect to the detection gap L _a1 between the axially outer revolution speed detecting sensor 20a and revolution speed detecting encoder 23a, less than the neutral value _{L a (L a1 <L a} ) becomes, The detection gap L _b1 between the revolution speed detection sensor 20b on the inner side in the axial direction and the revolution speed detection encoder 23b is larger than the neutral value L _b (L _b1 > L _b ). Regarding the rolling bearing unit provided on the left side of the vehicle, the amount of change ΔL _a (= L _a −L _a1 ), ΔL _b (= L _b1 ) when the vehicle turns right. -L _b ) becomes relatively large.

On the other hand, when the vehicle turns to the left, the hub 2 is moved outward in the axial direction (left side in FIG. 6) to the rolling bearing unit that is turned in the turning direction based on the balance between the centrifugal force and the gripping force. An axial load in the pulling direction is applied. As a result of the axial load, the hub 2 is displaced to the left in FIG. 6 with respect to the outer ring 1, so that both the revolution speed detection sensors 20a and 20b and the both revolution speed detection encoders 23a and 23b The axial distances (detection gaps) L _a2 and L _b2 between them are different from the neutral values (L _a , L _b ) as shown in FIGS. 7C and 8. Specifically, with respect to the detection gap L _a2 between the outer revolution speed detecting sensor 20a and revolution speed detecting encoder 23a, larger than the neutral value L _a will (L _a2> L _a), inside the The detection gap L _b2 between the revolution speed detection sensor 20b and the revolution speed detection encoder 23b is smaller than the neutral value L _b (L _b2 <L _b ). However, the axial load applied to the left wheel located inside the turning direction at the time of turning is an axial load in the direction in which the maximum value becomes small, and since it is relatively small, in the case of a rolling bearing unit that supports the left wheel inside the turning direction, The amount by which the hub 2 is displaced leftward in FIG. 6 with respect to the outer ring 1 is relatively small. As a result, regarding the rolling bearing unit provided on the left side of the vehicle, the amount of change ΔL _a (= L _a2 −L _a ), ΔL _b (= L _b −L _b2 ) is relatively small.

As a result, the detection value of the maximum value L _a2 and the minimum value L _a1 clearance, inside the revolving speed between the apparent street, outside of the revolution speed detecting sensor 20a and revolution speed detecting encoder 23a from FIG 8 The maximum value L _b1 and the minimum value L _b2 of the detection gap between the detection sensor 20b and the revolution speed detection encoder 23b are different. Under such conditions, in order to perform a design that satisfies the above conditions (1) and (2) at the same time, the outer minimum value L _a1 satisfies (1) of these (assuming L _a1 > 0). It is necessary to regulate the dimensions and specifications of each part so that the inner maximum value L _b1 satisfies (2). The width (= L _b1 -L _a1 ) between the minimum value L _a1 and the maximum value L _b1 is based on the respective revolution speed detection sensors 20a, 20b and the respective revolution speed detection encoders 23a based on the axial loads in both directions. 23b and the total of the relative displacement amounts (= L _b1 −L _b2 = L _a2 −L _a1 ). In consideration of such a large width (= L _b1 −L _a1 ), it is difficult to satisfy the conditions (1) and (2) at the same time and to improve the performance and reduce the cost.

  For example, in order to improve the detection accuracy by using permanent magnets in which S poles and N poles are alternately arranged on the detected surface as the both revolution speed detecting encoders 23a and 23b, It is necessary to increase the number of N poles (fine pitch). In such a case, the magnetic flux flowing between the S pole and the N pole adjacent in the circumferential direction is unlikely to reach a portion away from the detected surface. Accordingly, in order to improve the detection accuracy by using permanent magnets as the both revolution speed detecting encoders 23a and 23b, the detected surfaces of the both revolution speed detecting encoders 23a and 23b and the both revolution speed detecting sensors are used. It is preferable to make the axial distance from the detection surfaces 20a and 20b as small as possible. If a permanent magnet with a high magnetic flux density is used, or a sensor with high sensitivity is used as the two revolution speed detection sensors 20a and 20b, the two revolution speed detection is possible even if the axial distance is somewhat large. Although it is possible to detect the rotational speeds of the encoders 23a and 23b to some extent, it is inevitable that the cost increases.

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

  The present invention has been invented to realize a load measuring device for a rolling bearing unit capable of achieving both cost reduction and high performance in view of the above-described circumstances.

A load measuring device for a rolling bearing unit of the present invention includes an outer ring equivalent member, an inner ring equivalent member, a plurality of rolling elements, a pair of cages, first and second revolution speed detection encoders, The first and second revolution speed detection sensors and a calculator are provided.
Of these, the outer ring equivalent member has a double row 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 a double row of inner ring raceways on the outer peripheral surface.
In addition, a plurality of rolling elements are provided for each row in a state where a contact angle is given between the inner ring raceways and the outer ring raceways.
Further, both the cages hold the rolling elements of each row so as to roll freely.
Further, the first and second revolution speed detecting encoders are provided over the entire circumference in the opposing portions of the two cages, and the characteristics of the detected surface are alternately changed in the circumferential direction. And it is changed at equal intervals.
In addition, the first and second revolution speed detection sensors are provided between the two cages in a state of facing the two revolution speed detection encoders, and the revolution speeds of the rolling elements in the respective rows are provided. The rotational speed of the cage is detected.
The computing unit applies a load applied between the outer ring equivalent member and the inner ring equivalent member based on a detection signal that is sent from the both revolution speed detection sensors and represents the revolution speed of the rolling elements in each row. Is calculated.
The maximum value of the axial load applied between the outer ring equivalent member and the inner ring equivalent member is used under different conditions depending on the direction of the axial load.
Such a load measuring device for a rolling bearing unit according to the present invention includes a first revolution speed detection encoder and the first revolution speed detection sensor which approach each other when an axial load in a direction in which the maximum value increases is applied. The second revolution speed detection sensor and the second revolution speed detection sensor that approach each other when the axial load in the direction in which the maximum value decreases acts on the distance when the axial load is not applied. And the distance in a state where the axial load is not applied.

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, the distance between the first revolution speed detection encoder and the first revolution speed detection sensor, which changes with the axial load, respectively, It is possible to prevent a large difference from occurring between the revolution speed detection encoder and the distance between the second revolution speed detection sensor. In other words, the width between the minimum value (smaller value) and the maximum value (larger value) of these distances can be reduced.
As a result, it is possible to reliably detect the rotation of the revolution speed detection encoder without using an expensive revolution speed detection encoder or revolution speed detection sensor. If a high-performance (expensive) revolution speed detection encoder or revolution speed detection sensor is used, higher performance than before can be achieved. These facilitate the design for achieving both cost reduction and high performance of the load measuring device of the rolling bearing unit.

When the present invention is implemented, preferably, as described in claim 2, the first revolution speed detecting encoder and the first revolution in a state in which the maximum value of the relatively large axial load is applied and approach each other. The distance between the speed detection sensor and the distance between the second revolution speed detection encoder and the second revolution speed detection sensor in the state where the maximum value of the relatively small axial load is applied and approach each other is equal. To do.
With this configuration, the distance between the first revolution speed detection encoder and the first revolution speed detection sensor, and the second revolution speed detection encoder and the second revolution speed detection sensor. Minimizing the range between the minimum value (the smaller value) and the maximum value (the larger value) of the distance, it is possible to achieve both cost reduction and high performance at a high level. .

Preferably, as described in claim 3, as the first and second revolution speed detection encoders, the magnetic characteristics of the detected surfaces which are the side surfaces facing each other are changed alternately and at equal intervals. The first and second revolution speed detection sensors that change the output in response to the change in the magnetic characteristics are used.
When such a magnetic detection type structure is adopted, as described above, it is possible to realize a structure that is low in cost and is not easily affected by the grease existing in the rolling bearing unit, but it is affected by the size of the detection gap. Easy to receive. Therefore, it is meaningful to implement the present invention with the magnetic detection type structure as described above from the viewpoint of cost reduction and performance securing.
In this case, as described in claim 4, it is also preferable to use a permanent magnet in which S poles and N poles are alternately arranged on the detected surface as the first and second revolution speed detecting encoders. It is a form.

Preferably, when carrying out the present invention, as described in claim 5, the first and second revolution speed detecting encoders are installed on the surfaces of the pair of cages facing each other, and the first The second revolution speed detection sensor is preferably provided between the two cages.
If such a configuration is adopted, the first and second revolution speed detection encoders and the first and second revolution speed detection sensors can be effectively used in a limited space inside the rolling bearing. A small and light load measuring device for a rolling bearing unit can be realized.

Preferably, when carrying out the invention described in claim 5, the outer ring equivalent member is a stationary non-rotating wheel supported and fixed to a suspension device, and the inner ring equivalent member is a wheel. And a rotating wheel that rotates together. The first revolution speed encoder and the first revolution speed detection sensor are arranged on the outer side in the width direction of the vehicle, and the second revolution speed encoder and the second revolution speed detection sensor are also arranged on the inner side, respectively. Thus, the wheel is rotatably supported by the suspension device and used to obtain a load applied between the wheel and the suspension device.
As described above, in the case of the rolling bearing unit for supporting the wheel on the suspension device, in the structure in which the inner ring equivalent member rotates together with the wheel, of the axial load applied to the inner ring equivalent member, the axial load directed inward in the axial direction However, it tends to be larger than the axial load directed outward in the axial direction. Therefore, when the encoders and sensors are installed between the rolling elements in both rows, the operation and effect of the present invention can be sufficiently obtained by implementing the present invention under the above-described conditions. In the case of a structure in which the outer ring equivalent member rotates together with the wheel, or in the case of a structure in which each encoder and sensor is installed at a position sandwiching both rows of rolling elements from both sides in the axial direction, the inside and outside in the axial direction are The reverse of the case of claim 6 above.

Further, when the invention described in claim 6 described above is carried out, preferably, as described in claim 7, the first and second revolution speed detection sensors are arranged at the tip of the shaft of the outer ring equivalent member. The sensor unit provided on the opposite side with respect to the direction is inserted into a mounting hole formed in the intermediate portion of the outer ring equivalent member at the intermediate portion between the double row outer ring raceways. It protrudes radially inward from the inner peripheral surface of the part. And the said attachment hole is formed in the inner side part rather than the center position of the said double row outer ring track | orbit regarding the axial direction of this outer ring equivalent member.
If comprised in this way, this invention can be easily implemented with the load measuring apparatus of a small and lightweight rolling bearing unit.

When the present invention is carried out, the first and second revolution speed detecting encoders, which are made separately from both cages as described in claim 8, are coupled to these both cages. It is fixed, or it is made integrally with both cages as described in claim 9.
In any case, the first and second revolution speed detection encoders can be installed with good space efficiency.

  1 to 3 show an embodiment of the present invention. The feature of the present embodiment is that the outer revolution speed detection sensor 20a and the revolution speed detection encoder are applied in both directions between the outer ring 1b and the hub 2, regardless of the axial load that varies in each direction. 23a and a detection gap between the inner revolution speed detection sensor 20b and the revolution speed detection encoder 23b so that a large difference does not occur. Since the configuration and operation of the other parts are the same as in the case of the prior invention shown in FIG. 6 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. The description will focus on the features of

In the case of the present embodiment, the outer revolution speed detection sensor 20a and the outer revolution speed detection encoder 23a shown in FIG. 1A and FIG. axis direction distance (detection gap) L _a, greater than the axial distance (detection gap) L _B between the inner revolution speed detecting sensor 20b and the inner revolution speed detection encoder 23b between (L _A > L _B ). For this reason, in the case of the present embodiment, the mounting hole 10b for inserting the sensor unit 18 is formed at a portion closer to the inner side than the central position of the double row outer ring raceways 7 and 7 in the axial direction of the outer ring 1b. ing. Thus, the inner and outer detecting gap L _A, the degree to which different _{L B (L A / L B} ) , under conditions possible, a relatively large axial load applied in the axial direction side with respect to the hub 2 the maximum value Fa _Amax of, depending on the ratio of the maximum value Fa _Bmax relatively small axial load applied to the axially outward (Fa _Amax / Fa _Bmax) or the difference (Fa _Amax -Fa _Bmax), by calculation, Or experimentally.

Specifically, the above-described neutral state is set so that the minimum values L _Amin and L _Bmin of the inner and outer detection gaps L _A and L _B are substantially equal except for errors (L _{Amin ≈L Bmin} ). Both inner and outer detection gaps L _A and L _B are set. This point will be described with reference to FIGS. For the sake of simplicity, the following description will be made assuming that the hub 2 is displaced with respect to the outer ring 1b. In an actual case, the axial load is applied in a state where the outer ring 1b and the hub 2 are pushed (or pulled) in the opposite directions.

When the rolling bearing unit shown in FIG. 1 is located outside the turning direction of the vehicle, a relatively large axial load is applied to the hub 2 inward in the axial direction. For example, when the rolling bearing unit shown in FIG. 1 supports the left front wheel, the right axial load in FIG. 1 is applied to the hub 2 as the vehicle turns to the right. When this axial load reaches the maximum value Fa _Amax under conceivable conditions, as shown in FIG. 2B, the outer revolution speed detection sensor 20a and the outer revolution speed detection encoder 23a The axial distance (detection gap) between them becomes the minimum value L _Amin . At the same time, the axial distance (detection gap) between the inner revolution speed detection sensor 20b and the inner revolution speed detection encoder 23b becomes the maximum value L _Bmax .

On the other hand, when the rolling bearing unit is positioned inside the turning direction of the vehicle, a relatively small axial load is applied to the hub 2 outward in the axial direction. For example, when the rolling bearing unit shown in FIG. 1 supports the left front wheel, a leftward axial load in FIG. 1 is applied to the hub 2 as the left turns. When this axial load reaches the maximum value Fa _Bmax under possible conditions, as shown in FIG. 2C, the inner revolution speed detection sensor 20b and the inner revolution speed detection encoder 23b The axial distance between them (detection gap) becomes the minimum value _LBmin . At the same time, the axial distance (detection gap) between the outer revolution speed detection sensor 20a and the outer revolution speed detection encoder 23a becomes the maximum value L _Amax .

In the present embodiment, the minimum values L _Amin and L _Bmin of the inner and outer detection gaps L _A and L _B are substantially equal while taking into account the maximum axial loads Fa _Amax and Fa _Bmax in each direction (L _Amin ≒ L _Bmin ). Accordingly, the maximum values L _Amax and L _Bmax of the detection gaps L _A and L _B are substantially equal (L _{Amax ≈L Bmax} ). That is, as apparent from FIG. 3, in the present embodiment, the width between the minimum detection gap values L _Amin and L _Bmin and the maximum values L _Amax and L _Bmax (= L _Amax −L _{Amin ≈L Bmax−} L _Bmin ) is a sum of the respective revolution speed detection sensors 20a and 20b and the respective revolution speed detection encoders 23a and 23b and the relative displacement (= L _b1 −L _b2 = L _a2 −L _a1 ) Almost equal.

Thus, in the case of the present embodiment, the width between the minimum values L _Amin and L _Bmin and the maximum values L _Amax and L _{Bmax of} both detection gaps can be made smaller than in the case of the above-described prior invention. This point is clear when the distribution ranges of the two detection gaps are compared in FIG. 3 and FIG. 8 described above. In this embodiment, the width between the minimum values L _Amin and L _Bmin and the maximum values L _Amax and L _Bmax of both detection gaps is reduced in this way (the distribution range of both detection gaps is narrowed). In determining the axial distance between the two revolution speed detecting sensors 20a, 20b and the two revolution speed detecting encoders 23a, 23b, taking into account the two points (1) and (2) described above. In addition, it is easy to achieve both cost reduction and high performance.

  That is, since the distribution of the sizes of the two detection gaps is narrow, the largest axial load considered in the above condition (1), that is, the use state, is applied, and one of the revolution speed detection sensors 20a (20b) and the revolution speed. Even when the detection encoder 23a (23b) is closest, the revolution speed detection sensor 20a (20b) and the revolution speed detection encoder 23a (23b) do not interfere (do not rub), and the above ( 2), that is, even when the other revolution speed detection sensor 20b (20a) and the revolution speed detection encoder 23b (23a) are farthest away, the revolution speed detection by the revolution speed detection sensor 20b (20a) is detected. It becomes easy to reliably detect the rotation of the encoder 23b (23a).

Sectional drawing which shows the Example of this invention. In the case of this invention, the schematic diagram for demonstrating the state from which the distance of the 1st, 2nd revolution speed detection encoder and the 1st, 2nd revolution speed detection sensor changes based on an axial load. Similarly graph. 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 state to which the distance of the 1st, 2nd revolution speed detection encoder and the 1st, 2nd revolution speed detection sensor changes in the case of a prior invention based on an axial load. Similarly graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b Outer ring 2, 2a Hub 3, 3a Rotation side flange 4 Hub main body 5 Nut 6 Inner ring 7 Outer ring raceway 8 Inner ring raceway 9a, 9b Rolling elements 10, 10a, 10b Mounting hole 11 Displacement sensor 12 Sensor ring 13 Knuckle 14 Fixed side flange 15 Bolt 16 Screw hole 17 Load sensor 18 Sensor unit 19 Tip 20a, 20b Revolution speed detection sensor 21 Rotational speed detection sensor 22a, 22b Retainer 23a, 23b Revolution speed detection encoder 24 Rotational speed detection encoder 24

Claims (9)

  An outer ring equivalent member having a double row outer ring raceway on the inner peripheral surface, and an inner ring equivalent member having a double row 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; A plurality of rolling elements provided for each row in a state where a contact angle is given between both the inner ring raceways and the both outer ring raceways, and 1 each of which holds the rolling members of each row in a freely rolling manner. For detecting the first and second revolution speeds of the pair of cages, the characteristics of the surface to be detected, which are provided over the entire circumference of both cages, and alternately changing at equal intervals in the circumferential direction. An encoder, and first and second revolution speed detection sensors, which are provided in a state of being opposed to both the revolution speed detection encoders, and which detect the rotation speed of the cage, which is the revolution speed of the rolling elements of each row. , The rotation speed of each of the above-mentioned rows sent from these revolution speed detection sensors. An arithmetic unit for calculating a load applied between the outer ring equivalent member and the inner ring equivalent member based on a detection signal representing the revolution speed of the body, and an axial applied between the outer ring equivalent member and the inner ring equivalent member This is a rolling bearing unit load measuring device in which the maximum value of the load is used under different conditions depending on the direction of this axial load, and when an axial load in the direction of increasing the maximum value is applied. The distance between the first revolution speed detection encoder and the first revolution speed detection sensor approaching each other when the axial load is not applied is determined when the axial load in the direction of decreasing the maximum value is applied. From the distance between the second revolution speed detection encoder and the second revolution speed detection sensor approaching each other in a state where the axial load is not applied. Load measuring device for large the rolling bearing unit.   The distance between the first revolution speed detection encoder and the first revolution speed detection sensor in a state where the maximum value of the relatively large axial load is added and approach each other, and the maximum value of the relatively small axial load is added. 2. The load measuring device for a rolling bearing unit according to claim 1, wherein the distance between the second revolution speed detection encoder and the second revolution speed detection sensor in a state of approaching each other becomes equal.   The first and second revolution speed detection encoders change the magnetic characteristics of the surface to be detected alternately and at equal intervals, and the first and second revolution speed detection sensors have the magnetic characteristics. The load measuring device for a rolling bearing unit according to any one of claims 1 to 2, wherein the output is changed in response to the change.   4. The load measuring device for a rolling bearing unit according to claim 3, wherein the first and second revolution speed detecting encoders are permanent magnets in which S poles and N poles are alternately arranged on a detected surface.   The first and second revolution speed detection encoders are installed on the mutually opposing surfaces of the pair of cages, and the first and second revolution speed detection sensors are located between the two cages. The load measuring device for a rolling bearing unit according to any one of claims 1 to 4, wherein the load measuring device is provided on the rolling bearing unit.   The outer ring equivalent member is a stationary non-rotating wheel supported and fixed to the suspension device, the inner ring equivalent member is a rotating wheel that rotates together with the wheel, and the first revolution speed encoder and the first revolution speed detection sensor are the width of the vehicle. The second revolution speed encoder and the second revolution speed detection sensor are also arranged on the inner side in the direction outward, respectively, so that the wheel is rotatably supported by the suspension device and between the wheel and the suspension device. The load measuring device for a rolling bearing according to claim 5, which is used for obtaining a load applied to the rolling bearing.   A sensor unit in which the first and second revolution speed detection sensors are provided on the opposite side with respect to the axial direction of the outer ring equivalent member at the tip thereof is a portion between the double row outer ring raceways at the axial intermediate portion of the outer ring equivalent member. Is inserted into the mounting hole formed in the outer ring, and its tip protrudes radially inward from the inner circumferential surface of the intermediate portion of the outer ring equivalent member. The load measuring device for a rolling bearing unit according to claim 6, wherein the load measuring device is formed at a portion closer to the inside than the center position of the outer ring raceway in the row.   The load measurement of the rolling bearing according to any one of claims 1 to 7, wherein first and second revolving speed detection encoders, which are made separately from the two cages, are coupled and fixed to the two cages. apparatus. The load measuring device for a rolling bearing according to any one of claims 1 to 7, wherein the first and second revolution speed detecting encoders are integrally formed with the two cages.

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