JP5482476B2 - Physical quantity measuring device for rolling bearing units - Google Patents

Description

  The present invention relates to an improvement in a physical quantity measuring device for a rolling bearing unit which is used for rotatably supporting a vehicle wheel with respect to a suspension device and measuring a physical quantity such as an axial load acting on the wheel.

  Friction force acting on the contact surface (ground surface) between the wheel (tire) and the road surface (axial load on the ground surface, For the purpose of knowing (grip force), for example, various types of rolling bearing units with a load measuring device as described in Patent Document 1 are known. An example of such a rolling bearing unit with a load measuring device will be described with reference to FIGS. Hubs 2 that rotate together with the wheels while being supported and fixed to the inner ring side of the outer ring 1 that does not rotate even when used while being supported and fixed to a structural member of a suspension device such as a knuckle are rolling elements. A plurality of balls 3 and 3 are rotatably supported. A preload is applied to each of the balls 3 and 3 together with contact angles opposite to each other (in combination with the back surface).

  Further, the inner end of the hub 2 in the axial direction (inner with respect to the axial direction means the center side in the width direction of the vehicle when assembled to the vehicle. In this specification, the cylindrical encoder 4 is supported and fixed concentrically with the hub 2. A pair of sensors 6 a and 6 b are supported inside a bottomed cylindrical cover 5 that closes the inner end opening of the outer ring 1, and the detection parts of both the sensors 6 a and 6 b are connected to the encoder 4. The outer peripheral surface, which is the detection surface, is placed close to and opposed to the detection surface. Of these, the encoder 4 is made of a magnetic metal plate. In the front half of the outer peripheral surface of the encoder 4 (the inner half in the axial direction), which is the detection surface, the through holes 7 and 7 and the column portions 8 and 8 are alternately arranged at equal intervals in the circumferential direction. It is arranged.

  The boundaries between the through holes 7 and 7 and the pillars 8 and 8 are inclined at the same angle with respect to the axial direction of the encoder 4, and the inclined direction with respect to the axial direction is set to the intermediate portion in the axial direction of the encoder 4. The directions are opposite to each other. Accordingly, each of the through holes 7 and 7 and each of the pillars 8 and 8 has a “<” shape with the axially intermediate portion protruding most in the circumferential direction. And among the axially outer half part and the axially inner half part of the detected surface, the inclination directions of the boundaries are different from each other, the axially outer half part is defined as the first characteristic changing part 9, and the axially inner half part This portion is the second characteristic changing portion 10.

  Each of the sensors 6a and 6b is composed of a permanent magnet and a magnetic sensing element constituting a detection unit. These two sensors 6a and 6b are supported and fixed inside the cover 5, with the detection part of one sensor 6a serving as the first characteristic changing part 9 and the detection part of the other sensor 6b serving as the second sensor. The characteristic changing portions 10 are respectively close to and opposed to each other. The positions where the detection units of both the sensors 6a and 6b face the characteristic changing units 9 and 10 are the same in the circumferential direction of the encoder 4 or are shifted by a known value. Further, in the state where an axial load is not applied between the outer ring 1 and the hub 2, a portion that protrudes most in the circumferential direction in the axial direction intermediate portion of each of the through holes 7 and 7 and the column portions 8 and 8 (boundary boundary). The position where each member is installed is regulated so that the portion where the inclination direction changes) is just at the center position between the detection portions of the sensors 6a and 6b.

  In the case of a rolling bearing unit with a load measuring device configured as described above, when an axial load acts between the outer ring 1 and the hub 2 and the outer ring 1 and the hub 2 are relatively displaced in the axial direction, the two sensors The phase at which the output signals 6a and 6b change is shifted. That is, in the neutral state in which an axial load is not applied between the outer ring 1 and the hub 2, the detecting portions of the sensors 6a and 6b are on the solid lines A and B in FIG. It faces a portion that is shifted from the most protruding portion by the same amount in the axial direction. Accordingly, the phases of the output signals of the two sensors 6a and 6b coincide with each other as shown in FIG.

  On the other hand, when a downward axial load is applied to the hub 2 to which the encoder 4 is fixed as shown in FIG. 10A, the detecting portions of the sensors 6a and 6b are shown in FIG. , Opposite to the portions that are different from each other in the axial direction from the most protruding portion. In this state, the phases of the output signals of the sensors 6a and 6b are deviated as shown in FIG. Further, when an upward axial load is applied to the hub 2 to which the encoder 4 is fixed as shown in FIG. 10A, the detecting portions of both the sensors 6a and 6b are connected to the chain line H shown in FIG. The deviation in the axial direction from the uppermost part, that is, the most protruding part, is opposed to different parts in the opposite direction to the above case. In this state, the phases of the output signals of the sensors 6a and 6b are deviated as shown in FIG.

  As described above, in the case of a conventionally known structure as described in Patent Document 1, the phase of the output signals of the sensors 6a and 6b is applied between the outer ring 1 and the hub 2. It shifts in the direction corresponding to the acting direction of the axial load (the direction of the relative displacement between the outer ring 1 and the hub 2 in the axial direction). Further, the degree to which the phase of the output signals of the sensors 6a and 6b is shifted due to the axial load (relative displacement amount) increases as the axial load (relative displacement amount) increases. Accordingly, based on the presence or absence of the phase shift of the output signals of both the sensors 6a and 6b and the direction and magnitude of the shift, the direction of the relative displacement amount in the axial direction between the outer ring 1 and the hub 2 and The magnitude and the direction and magnitude of the axial load acting between the outer ring 1 and the hub 2 are determined. The relative displacement in the axial direction is based on the ratio of the phase difference between the output signals of the sensors 6a and 6b to one cycle of the output signals of the sensors 6a and 6b (phase difference / 1 cycle = phase difference ratio). The processing for calculating the amount and the load is performed by an arithmetic unit (not shown). For this reason, in this computing unit, the relationship between the phase difference ratio, the relative displacement amount in the axial direction, and the load, which has been examined in advance by theoretical calculation or experiment, is incorporated in a calculation formula, a map, or the like. .

  In addition, the structure which uses the thing made from the permanent magnet magnetized in the radial direction as an encoder is also shown, for example in FIGS. 32-34 of patent document 1, and the description of each figure in the specification of this patent document 1. It has been known for some time. In such an encoder made of a permanent magnet, the S pole and the N pole are alternately arranged at equal intervals in the circumferential direction on the outer peripheral surface which is a detected surface. The boundary between the S pole and the N pole adjacent to each other in the circumferential direction has a “<” shape with the middle portion in the axial direction protruding most in the circumferential direction. When such a permanent magnet encoder is used, a permanent magnet on the sensor side is not necessary.

  Regardless of the structure of the encoder that incorporates the encoder, the axial load is calculated using the physical quantity measuring device of the rolling bearing unit. In order to ensure the measurement accuracy of the axial load, the positioning accuracy in the axial direction between the encoder and the sensor is required. It is necessary to secure. For this reason, conventionally, it has been considered to secure the positioning accuracy by using, for example, a technique described in Patent Document 2. However, simply securing this positioning accuracy is not sufficient in terms of ensuring the measurement accuracy. This is because the dimensions of the holder 11 that embeds and supports the sensors 6a and 6b change with changes in the environmental temperature. That is, in order to easily support and fix the two sensors 6a and 6b at appropriate positions, the sensor unit 12 is configured by embedding and supporting these sensors 6a and 6b in a predetermined position in the synthetic resin holder 11. The sensor unit 12 may be supported and fixed to a fixed part such as the cover 5.

  However, the linear expansion coefficient of the synthetic resin constituting the holder 11 is larger than the linear expansion coefficient of each member of the rolling bearing unit and the iron-based alloy constituting the cover 5. For this reason, the positional relationship between the detection portions of the sensors 6a and 6b and the detected surface of the encoder 4 shifts with changes in temperature. For example, in the case of the structure shown in FIG. 8, when the temperature rises, both the sensors 6a and 6b are shifted to the left in the figure with respect to the encoder 4, and as a result, the measured value of the axial load is shifted. This point will be described with reference to FIGS.

  In a state where an axial load does not act between the outer ring 1 and the hub 2 at room temperature, as shown in FIG. 11A, just at the center between the detection parts of the pair of sensors 6a and 6b, Consider a case where there is a portion where the inclination direction of the boundary between different characteristic portions changes. When the environmental temperature rises from this state and the holder 11 is thermally expanded, as shown in FIGS. 11A to 11B, the detected surface of the encoder 4 is the same as the case where the axial load is changed. And the detectors of the pair of sensors 6a and 6b are relatively displaced in the axial direction (vertical direction in FIG. 11). When such relative displacement occurs, the phase difference existing between the output signals of the sensors 6a and 6b changes as shown by the solid line → broken line in FIG.

  Thus, when the phase difference changes with the thermal expansion or contraction, the zero point of the relationship established between the phase difference and the axial load (the position in a state where the axial load is not acting). Deviation occurs in the value of the phase difference. For this reason, an error occurs in the measurement result of the axial load corresponding to the deviation. The error caused by such a cause can be reduced or eliminated by correcting the zero point on the arithmetic unit side while measuring the temperature around the bearing portion or the like. However, an excessive change in the phase difference caused by the thermal expansion or contraction is not preferable from the viewpoint of ensuring measurement accuracy. Therefore, it is desired to realize a structure that can sufficiently suppress the amount of change in the phase difference that occurs with the thermal expansion or contraction. In particular, the synthetic resin that is the material of the holder 11 is compared to a metal such as an iron-based alloy or aluminum-based alloy that is a material of other components such as the outer ring 1, the hub 2, the balls 3, 3, and the cover 5. The linear expansion coefficient is large. For this reason, it is desired to realize a structure that can sufficiently suppress the amount of change in the phase difference caused by thermal expansion or contraction of the holder 11.

  Corresponding to such circumstances, Patent Document 3 discloses that, for example, as shown in FIG. 13, the thermal expansion and contraction of the holder 11a constituting the sensor unit 12a are prevented from being linked to a load measurement error. The structure is described. In the case of the second example of this conventional structure, the holder 11a is supported to the cover 5a via a fixing ring 13. The fixing ring 13 is an L-shaped cross section made of a metal plate and is formed in an annular shape as a whole. A stepped cylindrical portion 14 and an inward flange-shaped circle provided at the axially outer end of the cylindrical portion 14 are provided. Annulus 15 is provided. Of these, the annular portion 15 is molded in the axially central portion (the portion that coincides with the central position O between the detection portions of the pair of sensors 6a and 6b) of the radially outer end portion of the holder 11a. doing. In this state, the inner end portion or the central portion (the portion having a larger diameter than the outer end portion) of the cylindrical portion 14 is fitted and fixed to the intermediate portion of the cover 5a by an interference fit. An encoder 4a made of a permanent magnet is fitted and fixed to the inner end of the hub 2 in the axial direction. The detectors of both the sensors 6a and 6b are opposed to the detected surface provided on the outer peripheral surface of the encoder 4a, with the width direction being one side and the other side.

  In the case of the second example of the conventional structure configured as described above, when the holder 11a is thermally expanded or contracted due to a temperature change during use, the sensors 6a and 6b are associated with each other in the axial direction. They are displaced in the opposite directions and with the same size with respect to the center position O as a reference. For example, when the holder 11a is thermally expanded, as shown in FIGS. 14A to 14B, both the sensors 6a and 6b are in the axial direction (the horizontal direction in FIG. 13 and the vertical direction in FIG. 14). Are displaced in the direction away from each other and by the same amount with respect to the central position O. As a result, for example, as indicated by a solid line → broken line in FIG. 15, the phases of the output signals of the sensors 6a and 6b change in the same direction and by the same magnitude. In the case of thermal contraction, the same result can be obtained only by changing the direction of change to the case of thermal expansion. Therefore, in the case of the second example of the conventional structure, even if the phase of the output signals of both the sensors 6a and 6b changes as the holder 11a thermally expands or contracts, both of the sensors 6a and 6b The phase difference existing between the output signals does not change. Therefore, the measurement accuracy of the axial load acting between the outer ring 1 and the hub 2 can be maintained well regardless of the temperature change during use.

  According to the second example of the conventional structure as described above, the measurement accuracy of the axial load in which the thermal expansion and contraction of the synthetic resin holder 11a having a large linear expansion coefficient acts between the outer ring 1 and the hub 2 is achieved. Can be prevented from worsening. However, with the structure shown in FIG. 13 as described above, in order to prevent the occurrence of errors due to the thermal expansion and contraction of the holder 11a, the detection units of the pair of sensors 6a and 6b are provided with the encoder 4, It must be arranged in the axial direction of 4a. In other words, the occurrence of the error cannot be prevented unless the straight line connecting the detection parts of both the sensors 6a and 6b is parallel to the central axis of the encoders 4 and 4a. On the other hand, the pair of sensors 6a and 6b for constituting the physical quantity measuring device is predetermined (for example, axial) between the output signals of both the sensors 6a and 6b for the convenience of installation in a narrow space. For various reasons, such as setting an initial phase difference of 180 degrees in a neutral state where no load is applied, it may be necessary to shift the arrangement in the circumferential direction. In such a case, the second example of the conventional structure cannot prevent the occurrence of the error.

  This point will be described with reference to FIG. As shown in FIG. 16, when the pair of sensors 6a and 6b are arranged not only in the axial direction but also in the circumferential direction of the encoder 4a, for example, along with the thermal expansion of the holder 11a made of synthetic resin, Not only does the distance (pitch between the detection parts) D in the axial direction of the sensors 6a and 6b extend, but the distance L in the circumferential direction also extends. Of these, the occurrence of an error based on the change in the distance D in the axial direction can be prevented in the second example of the conventional structure, but the occurrence of an error based on the change in the distance L in the circumferential direction is the second in the conventional structure. The example cannot prevent it.

  In the present invention, in view of the above-described circumstances, in order to measure a physical quantity related to a rolling bearing unit, a pair of sensors is wrapped in a synthetic resin holder in a state where the pair of sensors is shifted not only in the axial direction but also in the circumferential direction. The invention was invented to realize a structure that can reduce or eliminate the influence of thermal expansion and contraction of the holder in the case of a buried support structure.

The physical quantity measuring device for a rolling bearing unit according to the present invention includes a rolling bearing unit, an encoder, a pair of sensors, and a calculator.
Of these, the rolling bearing unit is a combination of an outer ring that is supported and fixed to the structural member of the suspension device and does not rotate during use, and a hub that rotates together with the wheel during use in a relatively rotatable manner via a plurality of rolling elements. Become.
The encoder is supported and fixed at the inner end of the hub in the axial direction to alternately change the characteristics of the detected surface, which is the outer peripheral surface concentric with the hub, in the circumferential direction and adjacent to the circumferential direction. Accordingly, the boundary between the characteristic portions that are different from each other is inclined with respect to the width direction of the detected surface that coincides with the axial direction of the encoder. The directions in which these boundaries are inclined with respect to the direction of the central axis are opposite to each other between the one half portion and the other half portion of the detected surface.
The two sensors are held by a synthetic resin holder supported on an inner peripheral surface of a cylindrical portion constituting a metal cover that is fitted and fixed to the inner end in the axial direction of the outer ring. Each detection part is divided into the one half part and the other half part of the said to-be-detected surface, and is made to oppose. And each output signal is changed corresponding to the characteristic change of the said to-be-detected surface accompanying rotation of the said encoder.
Further, the computing unit includes, based on output signals of the two sensors, a relative displacement amount in the axial direction between the outer ring and the hub, and an axial load acting between the outer ring and the hub. Calculate at least one of them.

In particular, in the physical quantity measuring device for a rolling bearing unit according to the present invention, the positions of the detecting portions of the two sensors are shifted in the circumferential direction in addition to the axial direction. Then, the position in the axial direction of the anchor plate portion formed in a state of being bent radially inward at a part of the anchor member fixed to the inner peripheral surface of the cylindrical portion of the cover is set to one of the two sensors. It is made to correspond with the position regarding the axial direction of the detection part of this sensor.
The direction in which the detection unit of the other sensor is displaced in the circumferential direction with respect to the detection unit of the one sensor is based on the thermal expansion and thermal contraction of the holder, The direction of movement of the detection part of the sensor is made to be the same as the direction of each boundary existing in the part of the detected surface where the detection part of the other sensor faces.

  The moving direction and the direction of each boundary are preferably completely matched, but depending on the accuracy required for physical quantity measurement, it may be roughly matched and a slight deviation is allowed. For example, if the angle at which the boundary between the characteristic portions existing on the outer peripheral surface of the encoder is inclined with respect to the circumferential direction of the detected surface is about 40 to 50 degrees, the required measurement accuracy is not particularly high. Deviations of about ± 10 degrees (maximum of about ± 25 degrees depending on the required accuracy) are allowed. When the tilt angle of the boundary is out of the range of 40 to 50 degrees (less than 40 degrees or more than 50 degrees), the allowable deviation becomes smaller. Therefore, it is preferable to restrict the tilt angle of the boundary to a range of 40 to 50 degrees, and most preferably, the tilt angle is set to 45 degrees.

For this reason, when the physical quantity measuring apparatus for a rolling bearing unit according to the present invention as described above is implemented, the boundary between the characteristic portions existing on the outer peripheral surface of the encoder as in the invention described in claim 2 is preferable. Is 45 degrees with respect to the circumferential direction of the surface to be detected.
When the invention described in claim 2 is implemented, more preferably, as in the invention described in claim 3, the length of the position of the detection unit of the pair of sensors is shifted in the axial direction. The length shifted in the circumferential direction is made equal to each other.
Alternatively, as in the invention described in claim 4, the length of the position of the detection unit of the pair of sensors shifted in the axial direction is different from the length shifted in the circumferential direction. However, the ratio of the two lengths is regulated so that the deviation between the moving direction and the direction of each boundary is within the above-mentioned range (± 10 to 25 degrees).
Alternatively, as in the invention described in claim 5, the length of the position of the detection portion of the pair of sensors shifted in the axial direction is different from the length shifted in the circumferential direction. The axial deviation amount is D, the circumferential deviation amount is L, and the angle at which the boundary between the characteristic portions existing on the outer peripheral surface of the encoder is inclined with respect to the circumferential direction of the detected surface is θ. In this case, the values of these quantities D, L, and θ are regulated so that tan θ = D / L is satisfied {θ = tan ⁻¹ (D / L)}.

According to the physical quantity measuring apparatus of the rolling bearing unit of the present invention configured as described above, a pair of sensors are provided in the synthetic resin holder in the circumferential direction in addition to the axial direction in order to measure the physical quantity related to the rolling bearing unit. Even though the structure is embedded and supported in a shifted state, it is possible to reduce or eliminate the influence of the thermal expansion and contraction of the holder.
That is, in the case of the structure of this example, the axial position of the anchor plate portion of the anchor member is matched with the position of the detection portion of one of the two sensors in the axial direction. For this reason, the position of the detection unit of this one sensor is fixed regardless of the temperature change, and the detection unit of the other sensor detects the detection of the one sensor in accordance with the thermal expansion and contraction of the holder. It is displaced in the axial direction and the circumferential direction with reference to the part. Since this displacement is along the boundary of the characteristic portion existing on the outer peripheral surface of the encoder, it is reduced that this displacement is linked to the phase difference between the output signals of the two sensors (in the case of the invention according to claim 4). ) To cancellation (in the case of inventions according to claims 3 and 5).

Sectional drawing which shows the 1st example of embodiment of this invention. The perspective view shown in the state which removed the cover incorporating the holder holding an anchor member and a sensor, and was seen from the diagonally upper left of FIG. In order to explain the displacement state of the pair of sensors when the sensor holder is thermally expanded, with the X-part enlarged view (A) of FIG. The schematic diagram (B) shown in the state seen from the radial direction of this encoder. Similarly, the schematic diagram for demonstrating the change state of the positional relationship of the detection part of a pair of sensor and the boundary of the to-be-detected surface of an encoder accompanying a temperature change. The figure similar to FIG. 3 which shows the 2nd example of embodiment of this invention. The figure similar to FIG. 3 which shows the 3rd example. The partial cutaway perspective view (A) of an anchor member which shows the same 4th example, and the enlarged view (B) equivalent to the X section of FIG. Sectional drawing which shows the 1st example of a conventional structure. The figure which looked at a part of encoder from the radial direction. The schematic diagram for demonstrating the reason for which an axial load is calculated | required. In order to explain the reason why the phase difference between the output signals of a pair of sensors changes with the thermal expansion of the holder, both these sensors and the encoder are taken out, and the normal state (A) and the state when the temperature rises ( B) and a schematic diagram. The diagram which shows the state from which the phase difference between the output signals of a pair of sensors changes with the thermal expansion of a holder. The principal part sectional drawing which is the 2nd example of the conventional structure, and shows the structure considered in order to suppress the measurement error accompanying the thermal expansion and thermal contraction of a holder. The figure similar to FIG. 11 for demonstrating the reason which can suppress a measurement error. The same figure as FIG. The same figure as FIG. 3 for demonstrating the problem which arises when a pair of sensors are shifted in the circumferential direction in addition to the axial direction.

[First example of embodiment]
1-4 show a first example of an embodiment of the present invention corresponding to claims 1 to 5. The physical quantity measuring device for a rolling bearing unit of this example includes a rolling bearing unit 16, an encoder 4b, a pair of sensors 6a and 6b, and a calculator (not shown).
Of these, the rolling bearing unit 16 includes an outer ring 1a, a hub 2a, and a plurality of balls 3, 3 each of which is a rolling element. Of these, the outer ring 1a is provided with a double row outer ring raceway on the inner peripheral surface and a stationary flange 17 on the outer peripheral surface. The stationary flange 17 is fixed to the suspension device with screws, and can be used even during use. Does not rotate. The hub 2a is provided with a double-row inner ring raceway and a rotation side flange 18 on the outer peripheral surface, and rotates with a wheel coupled and fixed to the rotation side flange 18 in use. The balls 3 and 3 are rotatably provided between the outer ring raceways and the inner ring raceways, and rotatably support the hub 2a on the inner diameter side of the outer ring 1a.

  The encoder 4b is formed by combining a core metal 19 made of a magnetic metal plate and having an L-shaped cross section and an encoder main body 20 made of a permanent magnet, and the core metal 19 is attached to the inner end of the hub 2a in the axial direction. It is supported and fixed concentrically with the hub 2a by externally fitting with an interference fit. On the outer peripheral surface of the encoder body 20, S poles and N poles are alternately arranged at equal intervals in the circumferential direction. The boundary between the S pole and the N pole adjacent to each other in the circumferential direction is inclined with respect to the direction of the central axis of the encoder 4b (the width direction of the outer peripheral surface of the encoder main body 20, which is the detection surface). In addition, the direction in which each boundary is inclined with respect to the direction of the central axis (agreement with the arrangement direction of the S pole and the N pole) is opposite to each other in one half and the other half of the detected surface. . Further, the angle at which each of the boundaries is inclined with respect to the direction of the central axis is the same (one hundred and fifty degrees in this example) in one half and the other half of the detected surface.

  Further, in the state in which the sensors 6a and 6b constitute the sensor unit 12b together with the holder 21, a fixing ring 13a as an anchor member is provided on the inner surface of the cover 5b fitted and fixed to the axially inner end opening of the outer ring 1a. It is supported and fixed through. The sensor unit 12b is formed by embedding and holding both the sensors 6a and 6b in a holder 21 made of synthetic resin while being shifted in the axial direction and the circumferential direction. Then, in a state where the cover 5b is fitted and fixed to the inner end of the outer ring 1a, the detecting portions of the sensors 6a and 6b are made to be pieces of the detected surface of the encoder 4b (the outer peripheral surface of the encoder body 20). The half part (the left half part in FIGS. 1, 3 and 4) and the other half part (the right half part in FIGS. 1, 3, and 4) are distributed and opposed in the circumferential direction. The output signals of both the sensors 6a and 6b are changed in response to the change in the characteristics of the detected surface accompanying the rotation of the encoder 4b. The output signals of both the sensors 6a and 6b are sent to a computing unit (not shown), and the computing unit calculates an axial load acting between the outer ring 1a and the hub 2a.

  In the case of this example, in order to improve the measurement accuracy of both the sensors 6a and 6b, a pair of Hall ICs are arranged to be shifted in the rotation direction of the encoder 4b as the sensors 6a and 6b. A dynamic Hall IC is used. The differential Hall IC is described in Patent Documents 4 and 5, etc., and is generally available on the market, so a detailed description of its structure and operation is omitted. In the illustrated example, the differential Hall IC is used as both the sensors 6a and 6b, and the center position of the detection part of both the sensors 6a and 6b is the central part of the pair of Hall ICs. .

  The above configuration is basically the above-mentioned patent document except that the sensors 6a and 6b are shifted in the circumferential direction and a differential Hall IC is used as the sensors 6a and 6b. This is the same as the conventional structure described in FIG. In particular, the physical quantity measuring device of the rolling bearing unit of the present example is characterized by the structure as described above, the coupling position of the core metal 19 and the holder 21, the position of the detection part of the sensors 6a and 6b, By appropriately restricting the relationship between the inclination angle of the boundary between the S pole and the N pole existing on the outer peripheral surface of the encoder body 20, the two sensors 6a, The phase difference between the output signals 6b is set so as not to deviate for reasons other than relative displacement in the axial direction between the outer ring 1a and the hub 2a. Therefore, the characteristic part of this example will be described in detail below.

  The fixing ring 13a is formed by bending a metal plate made of the same material as that of the cover 5b, such as a steel plate or a stainless steel plate (having substantially the same coefficient of linear expansion), thereby forming an entire L-shaped cross section. It is formed in an annular shape. Such a fixing ring 13 a includes a cylindrical fitting fixing portion 22, an annular anchor plate portion 23 bent at a right angle from the axially outer end portion of the fitting fixing portion 22 in the radial direction, and Consists of. Such a fixing ring 13a is fixed to the inner surface of the cover 5b by fitting the fitting fixing portion 22 into the cylindrical portion 24 of the cover 5b with an interference fit. The holder 21 embeds and holds the sensors 6a and 6b in a predetermined position along with injection molding, and is coupled and fixed to the anchor plate portion 23 of the fixing ring 13a (at the time of injection molding, the anchor plate portion 23 is fixed). Insert). In the case of this example, when the holder 21 is injection-molded in this way, the position (the center position in the thickness direction) of the anchor plate portion 23 in the axial direction is the axial direction of the sensors 6a and 6b. It is made to correspond with the position regarding the axial direction of the detection part of the inner side sensor 6b. Therefore, the positional relationship in the axial direction between the anchor plate portion 23 and the detection portion of the sensor 6b does not change regardless of the thermal expansion and contraction of the holder 21 due to the temperature change.

  Although illustration is omitted, a concave portion or a convex portion is provided in a part of the anchor plate portion 23 where the position in the circumferential direction coincides with the detection portion of the sensor 6b on the inner side in the axial direction (for example, an embossed shape) A protrusion is bent and a part of the holder 21 and the concave part or convex part are engaged with the concave and convex parts as the holder 21 is injection-molded. And based on this uneven | corrugated engagement, the detection part of the sensor 6b of the said axial inside is prevented from shifting | deviating not only to an axial direction but the circumferential direction with respect to the said anchor board part 23. FIG.

  As described above, the axially outer side sensor 6b is fixed to the anchor plate part 23 with respect to the axial direction and the circumferential direction. With the thermal expansion and thermal contraction of 21, the axial position and the circumferential position with respect to the anchor plate portion 23 change. In the case of this example, the positional relationship between the sensors 6a and 6b and the encoder main body so that no phase difference occurs between the output signals of the sensors 6a and 6b regardless of changes in both directions. The relationship between the inclination direction and the inclination angle (the arrangement direction of the S pole and the N pole) of the boundary between the S pole and the N pole existing on the outer peripheral surface of 20 is appropriately regulated.

  Specifically, the direction in which the detection part of the sensor 6a outside the axial direction is displaced in the circumferential direction with respect to the detection part of the sensor 6b inside the axial direction is as shown in FIG. In the illustrated example, the detection part of the sensor 6a outside the axial direction is present on the lower left side in FIG. 3B with respect to the detection part of the sensor 6b inside the axial direction. As the boundary between the S pole and the N pole with respect to the first characteristic changing portion 9a opposed to the detection portion of the sensor 6a moves away from the detection portion of the sensor 6b on the inner side in the axial direction, the boundary inclines in the lower left direction in the figure. ing. In this way, based on the thermal expansion and contraction of the holder 21, the moving direction of the detection unit of the sensor 6 a outside the axial direction with respect to the detection unit of the sensor 6 b inside the axial direction is the first characteristic change unit. This is the same as the direction of the boundary between the S pole and the N pole in the 9a portion.

  In the case of this example, the angle θ at which the boundary relating to both the first and second characteristic changing portions 9a and 10a is inclined with respect to the circumferential direction of both the characteristic changing portions 9a and 10a (see FIG. 4). Is 45 degrees for any of the characteristic changing portions 9a, 10a. Furthermore, the length (deviation amount) D in which the positions of the detection portions of the sensors 6a and 6b are displaced in the axial direction, and the length (deviation amount) L in the circumferential direction (see FIG. 3B). } Are equal to each other (D = L). Then, the detection part of the sensor 6b on the inner side in the axial direction is connected to the second characteristic change part 10a, and the detection part of the sensor 6a on the outer side in the axial direction is connected to the first characteristic change part 9a via a small gap. They are facing each other. For example, in a neutral state (normal temperature and an axial load is not acting between the outer ring 1a and the hub 2a), the detection part of one sensor 6a (6b) is the circumference of the S pole. The phase of the output signals of both sensors 6a and 6b is shifted by 180 degrees so that the detection part of the other sensor 6b (6a) faces the central part in the circumferential direction of the N pole at the same time as facing the central part in the direction. . The value of the phase difference in such a neutral state can be arbitrarily set in consideration of easy axial load calculation and the like.

  According to the physical quantity measuring apparatus of the rolling bearing unit of the present example configured as described above, the axial load based on the output signals of the sensors 6a and 6b irrespective of the thermal expansion and contraction of the holder 21 based on the temperature change. It is possible to prevent an error from occurring in the measured value. This point will be described below. In addition to the outer ring 1a and the hub 2a, the balls 3, 3 as well as the cored bar 19 and the cover 5b of the encoder 4b are thermally expanded and contracted as the temperature changes. However, each of these members 1a, 2a, 3, 19, and 5b is an iron-based alloy, the coefficient of linear expansion of each is small, and between these members 1a, 2a, 3, 19, and 5b is large. There is no difference. Therefore, the measurement error of the axial load accompanying the thermal expansion and thermal contraction of each of the members 1a, 2a, 3, 19, 5b can be almost ignored.

  In the case of the structure of this example, the axial position of the anchor plate portion 23 of the fixing ring 13a is made coincident with the axial position of the detection portion of the sensor 6b on the inner side in the axial direction. Further, the anchor plate portion 23 and the holder 21 are engaged with each other at a portion corresponding to the detection portion of the sensor 6b on the inner side in the axial direction, and there is no relative displacement in the circumferential direction at this portion. For this reason, the position of the detecting portion of the sensor 6b on the inner side in the axial direction is fixed regardless of the temperature change. And the detection part of the sensor 6a outside the axial direction is displaced in the axial direction and the circumferential direction with reference to the detection part of the sensor 6b inside the axial direction as the holder 21 is thermally expanded and contracted. Since the synthetic resin constituting the holder 21 is homogeneous as a whole and the temperature changes almost uniformly as a whole, the amount of change per unit length is substantially the same in the axial direction and the circumferential direction. In the case of this example, the displacement amount D in the axial direction of the detection portions of the sensors 6a and 6b and the displacement amount L in the circumferential direction {see FIG. 3B} are equal to each other (D = L ), The detection part of the sensor 6a on the outside in the axial direction is displaced in a direction of 45 degrees obliquely with respect to the detection part of the sensor 6b on the inside in the axial direction.

  The above points will be summarized and described with reference to FIG. 3B and FIG. The sensor 6b on the inner side in the axial direction remains in the position shown in FIG. 3B regardless of the volume change of the holder 21 accompanying the temperature change, and the position of the detection unit is the position of the point α in FIG. Never move. Further, the sensor 6a on the outside in the axial direction is at a position indicated by a solid line in FIG. 3B at a normal temperature, and its detection portion is at a position β in FIG. On the other hand, when the holder 21 expands as the temperature rises, the detection unit of the sensor 6a on the outer side in the axial direction moves to the position γ in FIG. This movement is performed in the direction of 45 degrees obliquely along (in parallel with) the boundary existing in the first characteristic changing portion 9a, so that the displacement from the point β position to the point γ position is There is no connection with the phase difference between the output signals of the sensors 6a and 6b. When the holder 21 contracts as the temperature decreases, the detection portion of the sensor 6a on the outside in the axial direction follows the boundary from the position β to the center side in the width direction of the detection surface of the encoder 4b. And move in the opposite direction. As a result, it is possible to accurately measure the axial load acting between the outer ring 1a and the hub 2a regardless of the thermal expansion and thermal contraction of the holder 21 accompanying the temperature change.

[Second Example of Embodiment]
FIG. 5 also shows a second example of an embodiment of the present invention corresponding to claims 1 to 5. The structure of this example is obtained by reversing the structure of the first example of the above-described embodiment inward and outward with respect to the axial direction. That is, in the case of this example, the axial dimension of the fitting fixing portion 22a of the fixing ring 13b is made larger than that in the first example of the embodiment, and the axial direction outer end portion of the fixing ring 13b is set. The axial position of the formed anchor plate portion 23 is made to coincide with the axial position of the detection portion of the sensor 6a outside in the axial direction. Accordingly, in the case of this example, the installation direction of the encoder 4b is also reversed with respect to the axial direction, and the inclination direction of the boundary between the S pole and the N pole adjacent in the circumferential direction is determined in the first embodiment. The reverse of the case of one example. Then, the position of the sensor 6a on the outside in the axial direction is fixed, and the detection unit of the sensor 6b on the inside in the axial direction is present in the second characteristic change unit 10a along with the thermal expansion and contraction of the holder 21 based on the temperature change. Displacement is made along the boundary. Since the configuration and operation of the other parts are the same as in the first example of the embodiment described above, overlapping illustrations and explanations regarding the equivalent parts are omitted.

[Third example of embodiment]
FIG. 6 shows a third example of an embodiment of the present invention corresponding to claims 1, 2, and 4. In the case of this example, the length D in which the positions of the detection portions of the pair of sensors 6a and 6b are shifted in the axial direction is different from the length L in which the positions are shifted in the circumferential direction. Specifically, the length L displaced in the circumferential direction is larger than the length D displaced in the axial direction (D <L). The inclination angle of the boundary between the S pole and the N pole existing on the outer peripheral surface of the encoder 4b is 45 degrees, as in the first example of the above-described embodiment and the second example of the above-described embodiment. In the case of this example, an error occurs in the measured value of the axial load based on the output signals of both the sensors 6a and 6b with the thermal expansion and contraction of the holder 21 based on the temperature change. The error can be kept small. Since the configuration and operation of other parts are the same as those of the first example of the above-described embodiment, overlapping illustrations and descriptions regarding the equivalent parts are omitted.

[Fourth Example of Embodiment]
FIG. 7 shows another example of the coupling structure of the synthetic resin holder 21 and the fixing ring 13c as a fourth example of the embodiment of the present invention. When carrying out the present invention, the positional relationship between the fixing ring 13c and the position-fixing side sensor 6b is determined regardless of a change in the volume of the holder 21 due to a temperature change. It is necessary to avoid shifting in both the axial direction and the circumferential direction. At the same time, it is necessary to combine the holders 21 so that the holders 21 do not fall from the fixing ring 13c inward in the radial direction. For this purpose, as described above, it is conceivable to form an embossed convex portion in a portion of the anchor plate portion 23 that matches the detection portion of the sensor 6b on the fixed position side. Therefore, the strength of the combination can be improved.

  Therefore, in the case of this example, a bent portion 25 is formed on the outer peripheral edge of the anchor plate portion 23, and a portion of the anchor plate portion 23 is passed through a portion aligned with the detection portion of the sensor 6b on the position fixing side. A hole 26 is formed. Then, based on the engagement between the synthetic resin constituting the holder 21 and the bent portion 25, the holder 21 is reliably prevented from falling radially inward from the fixing ring 13c, and the through hole 26 is provided. By making the synthetic resin enter, the fixing ring 13c and the position-fixing side sensor 6b are prevented from shifting in the circumferential direction. Since the configuration and operation of other parts are the same as those of the first example of the above-described embodiment, overlapping illustrations and descriptions regarding the equivalent parts are omitted.

  In the illustrated embodiment, the boundary between the S pole and the N pole existing on the detected surface of the encoder is shown as being inclined at 45 degrees with respect to the circumferential direction of the detected surface. This inclination angle θ is not limited to 45 degrees. Even when the tilt angle θ is other than 45 degrees, as in the invention according to claim 5, the shift amount D in the axial direction, the shift amount L in the circumferential direction, and the tilt angle of the detection unit of the pair of sensors. If θ is regulated so as to satisfy tan θ = D / L, it is possible to prevent an error in the measured value of the axial load accompanying thermal expansion and thermal contraction of the synthetic resin holder. However, if the tilt angle θ is a small value of less than 40 degrees, it becomes difficult to secure the width of each S pole and N pole, ensuring the number of each S pole and N pole existing on the detection surface, and leaking This is disadvantageous in terms of securing the amount of magnetic flux that reaches the pair of sensors by suppressing the magnetic flux. On the other hand, if the angle θ is increased beyond 50 degrees, the change in the phase difference between the output signals of the two sensors due to the axial displacement between the encoder and the pair of sensors is reduced. This is disadvantageous in terms of ensuring measurement accuracy. When the present invention is carried out, if the tilt angle θ is restricted to a range of about 30 to 60 degrees, it may be practically used depending on the application, but it is preferably in the range of 40 to 50 degrees, and most preferably 45 degrees. To do. Conversely, if the angle θ is less than 30 degrees or larger than 60 degrees, there are many disadvantages instead of no advantage, and it is impractical. When the present invention is carried out, an encoder 4 made of a magnetic metal plate as shown in FIGS. 8 to 10 can be used. In this case, a permanent magnet is incorporated on the sensor 6a, 6b side.

DESCRIPTION OF SYMBOLS 1, 1a Outer ring 2, 2a Hub 3 Ball 4, 4a, 4b, 4c Encoder 5, 5a, 5b Cover 6a, 6b, 6c Sensor 7 Through-hole 8 Pillar part 9, 9a First characteristic change part 10, 10a Second Characteristic changing portion 11, 11a holder 12, 12a, 12b sensor unit 13, 13a, 13b, 13c fixing ring 14 cylindrical portion 15 annular portion 16 rolling bearing unit 17 stationary side flange 18 rotating side flange 19 cored bar 20 encoder body 21 Holder 22, 22a Fitting fixing part 23 Anchor plate part 24 Cylindrical part 25 Bent part 26 Through hole

JP 2006-317420 A JP 2007-309683 A JP 2008-175546 A JP-A-8-220200 JP 2007-93467 A

Claims (5)

A rolling bearing unit, an encoder, a pair of sensors, and a calculator;
Of these, the rolling bearing unit is a combination of an outer ring that is supported and fixed to the structural member of the suspension device and does not rotate during use, and a hub that rotates together with the wheel during use in a relatively rotatable manner via a plurality of rolling elements. It consists of
The encoder is supported and fixed at the inner end in the axial direction of the hub, and alternately changes the characteristics of the detected surface, which is the outer peripheral surface concentric with the hub, with respect to the circumferential direction, and is adjacent to the circumferential direction. The boundary between different characteristic parts is inclined with respect to the width direction of the detected surface that coincides with the axial direction of the encoder, and each boundary is inclined with respect to the direction of the central axis. Are opposite to each other in the axial half and the other half of the detected surface,
The sensors are respectively detected in a state where they are held by a synthetic resin holder supported on an inner peripheral surface of a cylindrical portion constituting a metal cover fitted and fixed to an inner end portion in the axial direction of the outer ring. Are divided into one half and the other half of the detected surface to face each other, and each output signal is changed in response to a change in characteristics of the detected surface as the encoder rotates. ,
The computing unit is based on the output signals of the two sensors, and includes at least one of an axial relative displacement amount between the outer ring and the hub and an axial load acting between the outer ring and the hub. In the physical quantity measuring device for a rolling bearing unit,
The positions of the detection parts of both sensors are shifted in the circumferential direction in addition to the axial direction,
The position in the axial direction of the anchor plate portion formed in a state of being bent radially inward at a part of the anchor member fixed to the inner peripheral surface of the cylindrical portion of the cover, is one of the two sensors. It matches the position of the detection part in the axial direction,
The direction in which the detection unit of the other sensor is displaced in the circumferential direction with respect to the detection unit of the one sensor is based on the thermal expansion and contraction of the holder, and the direction of the other sensor with respect to the detection unit of the one sensor. The moving direction of the detection unit is a direction that is the same as the direction of each boundary existing in a portion of the detected surface where the detection unit of the other sensor opposes. Physical quantity measuring device.   The physical quantity measuring apparatus for a rolling bearing unit according to claim 1, wherein an angle at which a boundary between characteristic portions existing on an outer peripheral surface of the encoder is inclined with respect to a circumferential direction of a detected surface is 45 degrees.   The physical quantity measuring device for a rolling bearing unit according to claim 2, wherein the length of the positions of the detection portions of the pair of sensors shifted in the axial direction is equal to the length shifted in the circumferential direction.   The physical quantity of the rolling bearing unit according to any one of claims 1 to 2, wherein a length of the detection unit of the pair of sensors is different from each other in a length shifted in an axial direction and a length shifted in a circumferential direction. measuring device.   The length in which the positions of the detection portions of the pair of sensors are displaced in the axial direction is different from the length in which the detection portion is displaced in the circumferential direction. The axial displacement amount is D, and the circumferential displacement amount is L. The rolling according to claim 1, wherein tan θ = D / L is satisfied, where θ is an angle at which the boundary between the characteristic portions existing on the outer peripheral surface of the encoder is inclined with respect to the circumferential direction of the detected surface. Physical quantity measuring device for bearing unit.

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