JP2007205762A - Bearing equipped with rotational position detection section and rotation device and steering device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing equipped with a rotational position detection section for generating multi-rotational absolute position information which requires no special mechanism and hence can be manufactured in a compact size without increasing assembly cost. <P>SOLUTION: When the revolution numbers of a rotating race 7 and a cage 8 of a rolling bearing section 3 are detected by magnetic characteristics forming sections 11, 12, each of which has magnetic characteristics changing periodically in the circumferential direction and magnetic characteristics detection sections 18, 19 which face the magnetic characteristics forming sections 11, 12 to detect the magnetic characteristics, on the precondition that the revolution number of the rotating race 7 is equal to a revolution number corresponding to an absolute rotation angle range in which the revolution number of the rotating race 7 is desired to be detected or an integer which is the smallest integer exceeding the revolution number, the revolution number of the cage 8 is selected to be a value which is neither an integer nor a value in the vicinity of an integer at any integer rotational position smaller than or equal to the integer of the rotating race and which satisfies that the value obtained by dividing the revolution number of the rotating race by the revolution number of the cage is greater than two and smaller than three. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing with a rotational position detector capable of detecting the absolute position of multiple rotations of a rotating raceway, a rotating device and a steering device using the same.

2. Description of the Related Art Various types of bearings with a rotational position detecting unit in which an encoder function is added to a bearing in a motor have been proposed for the purpose of reducing the size and cost of a rotation control device including a motor and a rotary encoder.
For example, a bearing with a rotational position detection unit incorporating a resolver for detecting the rotational position has been proposed, but the resolver cannot obtain absolute rotational position information of multiple rotations exceeding 360 °. Actually, in an electric power steering device that assists the steering force of the steering wheel, it is necessary to detect the absolute rotational position of the multiple rotation of the steering wheel, and the rotational position in the unsteered state immediately after the device power supply is turned on Must also be detected as a multi-turn absolute rotational position.

Even if a rotary encoder or resolver used to control the rotational position of the motor is attached to the steering shaft that connects the steering wheel and the steering mechanism that steers the wheel, the rotational position at 360 ° can be detected, but multiple rotations can be detected. Whether or not it is an eye cannot be detected.
To solve this problem, there is a conventional example in which a multi-rotation position sensor is realized as a single rotation sensor. If a gear is mounted on the input shaft, a second gear having a larger number of teeth than that of the gear is combined with the former, and a rotation sensor is attached to the second shaft, one rotation of the second shaft makes many rotations of the input shaft. It can be made to correspond to rotation (for example, refer to patent documents 1).

In addition, the rotation shaft of the annular rotor of the resolver is screwed into the housing through a screw portion, and a change in the output voltage level due to a change in the relative position in the axial direction between the annular stator and the annular rotor due to the rotation is detected. A resolver structure capable of obtaining the absolute position of rotation and a multi-rotation absolute digital signal output method have also been proposed (see, for example, Patent Document 2).
Furthermore, a bearing with a rotation sensor capable of detecting the absolute position of positive and negative 2.5 rotations of the rotating wheel by a rotation position sensor integrally assembled with the bearing cage has also been proposed (for example, see Patent Document 3). .

Japanese Patent Laying-Open No. 2004-77483 (first page, FIG. 2) Japanese Patent Laying-Open No. 2003-202243 (first page, FIGS. 1 and 2) Japanese Patent Laying-Open No. 2004-308724 (first page, FIG. 1)

However, in the conventional examples described in Patent Documents 1 and 2, since a gear or screw mechanism is used in combination with gears having different rotational axes, the radial dimension increases. However, there is an unsolved problem that the cost of these mechanisms and assembly increases.
Further, in the conventional example described in Patent Document 3, since the preload is applied so that the rolling element does not slide relative to the rotating wheel, the cage that rotates as the rolling element revolves is rotated. Although it is assumed that there is no relative displacement with respect to the wheel, the sliding of the rolling element is a phenomenon that can occur. Once the slip occurs, the position data on the rotating wheel described in Patent Document 3 and the cage side In the method of referring to the multi-turn position table based on the position data, the accurate position can no longer be detected, and when trying to obtain the absolute angular position exceeding the positive and negative 2.5 rotations, the positive and negative 2.5 There is an unsolved problem that the absolute angular position cannot be determined at the angular position exceeding the rotational position.

  Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and does not require a special mechanism, and thus can be manufactured compactly without increasing the assembly cost. It is an object of the present invention to provide a bearing with a rotational position detecting unit capable of generating information, a rotating device using the same, and a steering device.

In order to achieve the above object, a bearing with a rotational position detector according to claim 1 comprises a rolling bearing portion having a rolling element held by a cage between a rotating raceway ring and a fixed raceway ring, and the rotating raceway. A first magnetic characteristic forming unit fixed to the ring and having a magnetic characteristic that periodically changes in the circumferential direction, and a first magnetic characteristic for detecting the magnetic characteristic opposite to the first magnetic characteristic forming unit Opposing the detection unit, a second magnetic property forming unit fixed to the cage and having a magnetic property that periodically changes in a circumferential direction, and facing the second magnetic property forming unit, A second magnetic property detector for detecting,
When the rotation speed of the rotating raceway is set to the nearest integer equal to or greater than the rotation speed corresponding to the absolute rotation angle range to be detected, the rotation speed of the cage is set to the rotation speed of the rotating raceway / holding The rotational speed of the vessel is more than 2 and less than 3, and is selected to be a value that is neither an integer nor a value near the integer at any integer rotation position less than or equal to the integer of the rotating raceway.

  A rotating device according to claim 2 is a rotating part, a bearing with a rotational position detecting part according to claim 1 that supports the rotating part, and a slip angle of a cage side rotational position of the bearing with the rotational position detecting part. Rotation that calculates and stores the multi-rotation position of the rotation unit based on the corrected slip angle obtained by correcting the reading value of the cage-side rotation position in the subsequent bearing with the rotation position detection unit using the slip angle. And a position reading device.

  Furthermore, the steering device according to claim 3 is a steer shaft that connects a steering wheel and a steering mechanism that steers the wheel, and a bearing with a rotational position detector according to claim 1 that supports the steering shaft. The slip angle at the cage side rotation position of the bearing with the rotation position detection unit is detected and stored, and the subsequent reading value of the cage side rotation position at the bearing with the rotation position detection unit is corrected using the slip angle. And a rotational position reading device that calculates a multi-rotation position of the steering shaft based on a corrected slip angle.

According to the present invention, the rotational position of the rotating raceway is detected by the first magnetic characteristic forming unit and the first magnetic characteristic detecting unit, and the rotational position of the cage is detected by the second magnetic characteristic forming unit and the second magnetic characteristic forming unit. By detecting with the magnetic characteristic detector and setting the rotation speed ratio of the rotating raceway and the cage so that at least one of them is a value other than an integer, the effect of accurately detecting multiple rotations can be obtained. It is done.
In addition, the slip angle of the cage side rotational position is detected and stored, and the multi-rotation position of the rotating unit is calculated based on the corrected slip angle obtained by correcting the read value of the cage side rotational position based on the slip angle. As a result, it is possible to calculate an accurate multi-rotation position regardless of the slip of the cage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention. In the figure, reference numeral 1 denotes a fixed portion having a central opening 2, which rotates within the central opening 2 via a rolling bearing 3. The shaft 4 is rotatably supported.
The rolling bearing 3 is rotated via a fixed race 5 that is fitted to the inner peripheral surface of the central opening 2 of the fixed portion 1 and a plurality of balls 6 as rolling elements on the inner peripheral surface of the fixed race 5. It has a radial bearing configuration that includes a rotating raceway ring 7 that is freely held and a cage 8 that holds each ball 6 at a predetermined interval in the circumferential direction.

A first magnetic property forming unit 11 is disposed on the bottom surface of the rotating raceway ring 7, and a second magnetic property forming unit 12 is disposed on the bottom surface of the cage 8.
As shown in FIG. 2, each of the first magnetic characteristic forming unit 11 and the second magnetic characteristic forming unit 12 has a semicircular portion of the lower surface of the magnetic ring 13 formed in a flat ring shape. The other half of the circumference is magnetized to the S pole, and as shown in FIG. 3, a magnetized pattern is formed which magnetically forms one cycle of sine waves in one rotation.

  Here, the cage 8 may be configured by molding a plastic containing magnetic powder into a cylindrical ring shape and magnetizing its flat annular end surface as shown in FIG. A similar magnetized pattern can be obtained, and with this configuration, the cage 8 has a sufficient length in the axial direction, which is convenient in design and does not peel off like a fixed magnet. Therefore, long-term use is possible and reliability can be improved.

  On the other hand, a cylindrical portion 15 is formed on the lower surface on the outer peripheral side of the fixed race 5, and a flange portion 16 extending inwardly from the bottom surface and facing the first and second magnetic property forming portions 11 and 12 has a concave shape in cross section. The support member 17 formed on the upper surface of the support member 17 is fixed, and the support member 17 is positioned 90 ° apart from the center axis of the rotary shaft 4 on the upper surface of the support member 17 facing the first and second magnetic property forming portions 11 and 12. First and second magnetic characteristic detectors 18 and 19 each including two magnetic sensors facing each other with a predetermined distance between the magnetic characteristic forming units 11 and 12 are disposed.

  Here, the first and second magnetic characteristic forming units 11 and 12 and the first and second magnetic characteristic detecting units 18 and 19 are configured such that, for example, the rotating raceway 7 and the cage 8 are both at an absolute angle of 0 °. In a certain state, the first and second magnetic characteristic forming units 11 and 12 are arranged so that the N-pole region and the S-pole region coincide with each other, and the first magnetic property detection unit 18 and the second magnetic property detection unit 18 One magnetic sensor 18a and 19a in the magnetic characteristic detecting unit 19 is disposed so as to face one boundary position P1 of the N-pole region and the S-pole region of the first magnetic property forming unit 11, and the first magnetic characteristic is arranged. The other magnetic sensors 18b and 19b in the detection unit 18 and the second magnetic characteristic detection unit 19 are shifted by 90 ° counterclockwise with respect to the magnetic sensors 18a and 19a, so that the N pole region of the first magnetic characteristic formation unit 11 It is arranged at a position facing the center ing.

Then, as shown in FIG. 4, sin θ and cos θ output from the magnetic sensors 18a and 18b of the first magnetic characteristic detector 18 are converted into a converter 30 that calculates the raceway rotation angle θ of the digital signal based on them. The sin φ and cos φ that are input and output from the magnetic sensors 19 a and 19 b of the second magnetic characteristic detection unit 19 are input to a converter 31 that calculates the holder rotation angle φ of the digital signal based on these, and these converters The raceway rotation angle θ and the cage rotation angle φ output from 30 and 31 are input to an arithmetic processing unit 32 configured by, for example, a microcomputer, and the arithmetic processing unit 32 calculates an absolute angle θn ^* of 10 rotations. The The arithmetic processing unit 32 is connected to a ROM 33 that stores arithmetic processing programs and the like, a RAM 34 that stores arithmetic results, and a nonvolatile memory 35.

  Here, the rotational speed ratio between the rotating raceway ring 7 and the cage 8 is between 2 and at most 3 corresponding to the thrust bearing. In order to be able to detect an absolute angle of 10 or more rotations of the rotating raceway 7, the rotational speed ratio is 2, 3, 5/2 = 2.5, 7/3 = 2.33, 8 / Do not match or approach any of 3 = 2.67 or 9/4 = 2.25. For this reason, in this embodiment, the rotation speed ratio between the rotating raceway ring 7 and the cage 8 is different from the above value, for example, 2.6 = 13/5 as a value between 5/2 and 8/3. It is set to become. As described above, if a rolling bearing having a rotational speed ratio of 2.6 is designed and manufactured, the converters 30 and 31 correspond to the rotational angle φ of the rotating race ring 7 and the bearing ring rotational angle θ. The cage rotation angle φ is output as shown in FIG.

In FIG. 4, the horizontal axis is an angular position within a range of ± 1800 degrees (total 3600 degrees) within 5 positive and negative rotations (total 10 rotations) of the rotary track ring 7. Every time the rotation angle of 7 is 360 degrees, it changes into a sharp sawtooth shape between +180 and -180 degrees. On the other hand, the cage rotation angle φ changes in a serrated shape with a loose angle between +180 degrees and −180 degrees at a ratio of 1/2 of the rotation angle of the rotating raceway ring 7.
In this way, a pair of angles (φ, θ) corresponding to the rotation angle of the rotating race 7 is obtained from the two converters 30 and 31, but the rotation angle around the cage rotation angle φ is rotated. FIG. 6 is a graph showing the relationship between the bearing ring rotation angle θ and the vertical axis.

  In FIG. 6, point O is the center position of rotation of the rotating raceway ring 7, and point A corresponds to the rotation angle rotated −5 from the center position, and point B corresponds to the rotation angle rotated +5 from the center position. ing. It can be seen that the cage rotation angle φ advances in the right direction and the rotating raceway rotation angle θ advances in the upward direction as it rotates in the positive direction from the point A. When the rotation angle θ of the rotating raceway reaches +180 degrees at the upper end, it changes to −180 degrees at the lower end. Similarly, when the cage rotation angle φ reaches +180 degrees at the right end, the cage transitions to −180 degrees at the left end. While repeating such a transition, it passes through the point O which is the center position, and reaches a point B of +5 rotations. Thus, in order for the rotating race 7 to obtain all the absolute rotation angles from the rotation angle of −5 to +5, the diagonal lines in FIG. 6 do not overlap and are close to each other. It is a necessary condition that there is no. That is, the number of rotations of the cage with respect to the number of rotations of the rotating raceway was selected so that the combination patterns of both rotation angle positions of the rotating raceway and the cage were all different within the absolute rotation angle range ± 1800 °. It will be.

In this way, by detecting the rotation angle θ (n) of the rotating race 7 and the rotation angle φ (n) of the cage 8, the detected rotation angle (φ (n), θ (n)) of the pair is detected. Based on the above, the true rotation angle θ (n) ^* of the rotating race 7 can be calculated.
That is, if the variables k and p are appropriate integers, the rotation angle θ (n) of the rotating race 7, the rotation angle φ (n) of the cage 8, and the true rotation angle θ (n) ^* The relationship of the following formula (1) is established.
θ (n) ^* = θ (n) + 360 × k (n) = R (φ + 360 × p−γ) (1)
Here, R is the ratio of the rotational speed of the rotating race 7 and the rotational speed of the cage 8, and γ is the initial phase, which is stored in advance in a predetermined storage area of the nonvolatile memory 35, for example.
Using this equation (1), the true rotation angle θ (n) of the rotating track ring 7 is uniquely determined from the rotation angle θ (n) of the rotating track ring 7 and the rotation angle φ (n) of the cage 8 obtained simultaneously. ) ^* Can be calculated.
In this case, k (n) is 0, ± 1, ± 2, ± 3, ± 4, or ± 5, and p (n) is 0, ± 1, or ± 2.

  In FIGS. 5 and 6 described above, the initial phase γ is set to “0” for the sake of simplicity. In FIG. 6, since no straight line that transitions from point A to point O overlaps or intersects, there is always only one rotation angle φ (n) corresponding to a certain rotation angle θ (n). For this reason, there is only one set of k (n) and p (n) that satisfies the above-described equation (4), and the value R of the rotation speed ratio is determined so as to be so.

For example, when the true rotation angle θ (n) ^* of the rotating race 7 is + 1300 °, the rotation angle θ = −140 ° and the rotation angle φ = + 140 °.
At this time, from the equation (1),
−140 + 360 × k = 2.6 (140 + 360 × p)
It can be seen that when the initial phase γ is zero, only k = 4 and p = 1 are satisfied for the variables k (n) and p (n) within the above range. By substituting the value of k thus obtained in the above equation (1), the true rotation angle θ ^* of the rotating race 7 can be accurately calculated as shown in the following (2).
θ (n) ^* = θ + 360k = −140 + 360 × 4 = 1300 (2)

FIG. 7 is a plot of the rotational position θ (n) ^* of the rotating race 7 thus obtained and the rotational angle (φ, θ) of the pair.
Thus, it can be accurately detected up to ± 5 rotations. However, the pair of rotation angles (φ, θ), which are measured values, are not necessarily obtained so that the equal sign holds as in the above equation (1) due to the influence of noise or the like. In such a case, the equal sign after the above equation (1) becomes ≒, so practically, k (n) and p (n) satisfying the following equation are found by providing a small allowable width ε. Is preferred.
−ε <θ + 360 × k (n) −R (φ + 360 × p−γ) <ε (3)
Here, the allowable width ε is set to a small value of about 1 °, for example.

Next, γ is “0” as a method for accurately calculating the rotational position θ (n) ^* of the inner ring even when the rolling element of the bearing slips relative to the raceway and the position of the cage 8 slightly shifts. It explains including the case where it is not. It is assumed that a pair of rotation angles (φ, θ) should be obtained at a certain point in time, but the cage 8 is shifted by δ degrees to obtain a pair angle (φ ′ = φ + δ, θ).
In this case, k (n) and p (n) satisfying the following expression (4) may be found according to the above expression (3).
−ε ′ <θ + 360 × k (n) −R (φ ′ + 369 × p (n) −γ) <+ ε ′ (4)

Actually, since the bearing is used with a preload applied, even if the rolling element slips temporarily, it is a minute amount. Therefore, k (n) and p (n) satisfying the above equation (4) always exist for a small value of ε ′ considering another allowable width. Can be accurately calculated as θ (n) ^* = θ + 360 × k (n). At this time, it is desirable to simultaneously update the initial phase to γ−δ instead of γ. If the difference between the true rotation angle θ ^* and the calculated value R (φ ′ + 360 × p (n) −γ) using φ ′ is Δ, Δ = −Rδ, so that the new initial phase γ−δ Can be calculated by the following equation (5).
γ−δ = γ + Δ / R (5)
By replacing this γ + Δ / R with γ and storing it in the nonvolatile memory 35, the influence of the previous shift amount δ of the cage 8 can be removed in the subsequent calculation of the true rotation angle θ ^* .

  For this reason, the arithmetic processing unit 32 executes an absolute rotation angle calculation process shown in FIG. In this absolute rotation angle calculation process, first, in step S1, the rotating raceway rotation angle θ (n) and the cage rotation angle φ (n) ′ input from the converters 30 and 31 are read. Here, the cage rotation angle φ (n) ′ is equal to the rotation angle deviation of the cage 8 when the rotation position deviation of the cage 8 with respect to the rotating raceway ring 7 does not occur. It is expressed as a value obtained by adding the amount δ, and φ (n) ′ = φ (n) + δ.

Next, the process proceeds to step S2, and the ratio R of the rotational speed of the rotating race 7 and the rotational speed of the cage 8 stored in the predetermined storage area of the nonvolatile memory 35, the allowable value ± ε ′, and the initial phase γ are used. Thus, integer variables k (n) and p (n) satisfying the inequality of the equation (4) are calculated.
Next, the process proceeds to step S3, where it is determined whether or not there are integer variables k (n) and p (n) satisfying the inequality of the above equation (4), and the integer variables k (n) and p (n) are determined. If (n) does not exist, the process proceeds to step S4, an error flag Fe representing an operation error is set to "1", and the process is terminated, and integer variables k (n) and p (n) are set. If the pair exists, the process proceeds to step S5.

In step S5, the true rotation angle θ ^* of the rotating race 7 is calculated by performing the following equation (6) based on the current measurement value θ (n) and the calculated k (n). The calculated rotation angle θ ^* is output as the rotation position.
θ ^* = θ (n) + 360 × k (n) (6)
Next, the process proceeds to step S6, and the calculation of the following formula (7) is performed to calculate a comparative rotation angle θ (n) ′ based on the cage rotation angle φ (n) ′.
θ (n) ′ = R (φ (n) ′ + 360 × p (n) −γ (n)) (7)

Next, the process proceeds to step S7, and the following equation (8) is calculated to calculate the deviation Δ between the true rotation angle θ ^* and the comparison rotation angle θ (n) ′.
Δ = θ (n) ^* −θ (n) ′ (8)
Next, the process proceeds to step S8, and the next initial phase γ (n) is calculated by performing the following equation (9) based on the calculated deviation Δ and the initial phase γ (n) stored in the nonvolatile memory 35. +1) is calculated.
γ (n + 1) = γ (n) + Δ / R (9)
Next, the process proceeds to step S9, where the calculated next initial phase γ (n + 1) is updated and stored in the initial phase storage area formed in the nonvolatile memory 35 as γ (n), and then the process proceeds to step S10. After resetting the error flag Fe to “0”, the process returns to step S1.

Next, the operation of the first embodiment will be described.
Assuming that the rotating shaft 4 is now stopped, even in this stopped state, the magnetic sensors 18a and 18b of the first magnetic characteristic detecting unit 18 face the first magnetic characteristic forming unit 11, and the second magnetic Since the magnetic sensors 19a and 19b of the characteristic detecting unit 19 are opposed to the second magnetic characteristic forming unit 12, the detection signals of sin θ, cos θ and sin φ, cos φ are converted from the magnetic sensors 18a, 18b and 19a, 19b, respectively. Supplied to vessels 30 and 31. Therefore, sin θ / cos θ and sin φ / cos φ are calculated by the converters 30 and 31 to calculate tan θ and tan φ, and from these tan θ and tan φ, the raceway rotation angle θ (n) and the cage rotation angle φ (n) are calculated. Is input to the arithmetic processing unit 32 as a digital value.

Therefore, the arithmetic processing unit 32 executes the absolute rotation angle calculation process of FIG. 8 to read the raceway ring rotation angle θ (n) and the cage rotation angle φ (n) (step S1), and then read them. The above-described equation (4) based on the bearing ring rotation angle θ (n), the cage rotation angle φ (n), the preset allowable width ± ε ′, the rotation speed ratio R, and the initial phase γ (n). The variables k (n) and p (n) satisfying the above are calculated.
At this time, for example, assuming that the rotation axis is at an absolute rotation angle of 0 °, both the raceway ring rotation angle θ (n) and the cage rotation angle φ (n) ′ are “0”. Variables k (n) and p (n) satisfying the expression are both “0”.

Thus, since there exist variables k (n) and p (n) that satisfy the equation (4), when the true rotation angle θ (n) ^* is calculated according to the equation (6), the rotation angle θ ( n) ^{* is} also “0”.
At this time, since the true rotation angle θ (n) ^* and the raceway ring rotation angle θ (n) input from the converter 30 coincide with each other, the deviation Δ calculated according to the equation (8) is also “0”. The initial phase γ (n + 1) calculated according to the above (9) is also only the original initial phase γ, and this is updated and stored in the initial phase storage area formed in the nonvolatile memory 35 as γ (n). The

  When the rotary shaft 4 is rotated forward from the stopped state at an absolute angle of 0 ° of the rotary shaft 4, based on the sin θ and cos θ detected by the magnetic sensors 18a and 18b of the first magnetic characteristic detector 18 accordingly. 5 increases in the positive direction as shown in FIG. 5, and simultaneously, sin φ and cos φ detected by the magnetic sensors 19a and 19b of the second magnetic characteristic detector 19 are increased. As shown in FIG. 5, the cage rotation angle φ calculated by the converter 31 gradually increases in the positive direction with respect to the raceway rotation angle θ.

In this state, since the race ring rotation angle θ has not reached 180 °, k = 0 and p = 0 are maintained, and the true rotation angle θ ^* is increased as shown in FIG. Accordingly, the initial phase γ (n) is sequentially updated and stored, and the influence of the slip of the cage 8 is removed.
Thereafter, when the rotation angle of the rotary shaft 4 exceeds 180 ° and becomes 181 °, for example, the raceway rotation angle θ becomes −179 °, so the variable k becomes “1” and the variable p remains “0”. To do.

Therefore, the true rotation angle θ ^* calculated according to the above (6) is −179 ° + 360 × 1 = 181 °, which is a value that accurately corresponds to the rotation angle of the rotating shaft 4.
Thereafter, when the rotation angle of the rotating shaft 4 becomes around 500 ° and the cage rotation angle φ exceeds 180 ° and becomes −179 °, the variable p satisfying the above (4) becomes “1”, The existence of the variables k (n) = 1 and p (n) = 1 is continued, and the calculation of the true rotation angle θ ^* by the equation (6) is continued.

In this way, each time the sign of the raceway rotation angle θ (n) ′ is sequentially reversed, the variable k is increased by “1”. Similarly, every time the sign of the cage rotation angle φ (n) is reversed. By increasing the variable p by “1”, the true rotation angle θ ^* can be accurately detected until the forward rotation of the rotating shaft 4 is rotated five times as shown in FIG.
Further, when the rotating shaft 4 is reversed, the variable k is decreased by “−1” every time the sign of the raceway rotation angle θ (n) ′ is reversed from negative to positive in the same manner as described above, and the cage rotates. Each time the angle φ (n) is inverted from negative to positive, the variable p is decreased by “−1”, and the true rotation angle θ ^* of the rotating shaft 4 can be accurately detected as shown in FIG. it can.

If the variables k and p satisfying the equation (4) cannot be obtained, the process proceeds from step S3 to step S4, the error flag Fe is set to “1”, and a rotation angle detection error is notified. Is done.
Thus, according to the above embodiment, by producing the bearing 3 in which the ratio R between the rotational speed of the rotating race 7 and the rotational speed of the cage 8 is set to 2.6 = 13/5, for example, this bearing 3 can be accurately detected within a range of ± 5 rotations where the rotation angle θ ^* of the rotation shaft 4 is desired to be detected.

Moreover, the deviation Δ is calculated by subtracting the comparison rotation angle θ (n) ′ based on the cage rotation angle φ (n) ′ from the true rotation number θ (n) ^* , and based on this, the deviation Δ is calculated (9). Since the next initial phase γ (n + 1) is calculated by calculating the equation and stored as the initial phase γ (n), the rotational deviation amount of the cage 8 is always monitored, Since the rotational deviation amount is corrected, the true rotational angle θ (n) ^* can be accurately calculated regardless of the rotational deviation amount of the cage 8.

In the first embodiment, the case where the ratio R of the rotational speed of the rotating raceway 7 and the rotational speed of the cage 8 is set to 2.6 has been described. However, the present invention is not limited to this. The ratio R is 2.1 (= 21/10), 2.2 (= 11/5), 2.3 (= 23/10), 2.7 (27/10) or a rational number in the vicinity thereof Alternatively, even if the value is set to an irrational value, the characteristic lines of the bearing ring rotation angle θ and the cage rotation angle φ in FIG. 6 do not overlap each other within ± 5 rotations. The rotation angle can be detected.
In the first embodiment, the case where the inner ring rotates has been described. However, the present invention is not limited to this, and the present invention can also be applied to the case where the outer ring rotates.

Next, a second embodiment when the present invention is applied to an electric power steering apparatus will be described with reference to FIG.
In the second embodiment, an output shaft 102 (pinion shaft) is connected to the vehicle front side of a lower shaft 101 (input shaft) on which a steering wheel (not shown) is mounted. A steering gear rack 103 is engaged with the output shaft 102 (pinion shaft). The rack 103 is always pressed by being elastically biased toward the output shaft (pinion shaft) 102 by the elastic body 104 or the like.

The base end of the torsion bar 106 is press-fitted and fixed to the output shaft 102, and the torsion bar 106 extends inside the hollow input shaft 101, and the tip thereof is at the end of the input shaft 101. It is fixed.
Torque sensor detection grooves 107 are formed on the vehicle front side of the input shaft 101, and torque sensor sleeves 108 are disposed radially outward of these grooves 107. A coil 109, a substrate, and the like are provided outside the sleeve 108 in the radial direction.

A worm wheel 112 that meshes with a worm 111 that is a drive shaft of the electric motor 110 is fitted to the output shaft 102.
Therefore, the steering force generated when the driver steers the steering wheel (not shown) is applied to a steered wheel (not shown) via the input shaft 101, the torsion bar 106, the output shaft 102, the rack and pinion mechanism, the tie rod, and the like. Communicated.

Further, the rotational force of the electric motor 110 is transmitted to the output shaft 102 via the worm 111 and the worm wheel 112, and an output is obtained by appropriately controlling the rotational force and the rotational direction of the electric motor 110. An appropriate steering assist torque can be applied to the shaft 102.
In the present embodiment, in the worm gear reduction mechanism, the housing 121 that covers the input shaft 101 side and the housing 122 that covers the output shaft 102, the worm 111, and the worm wheel 112 are combined.
These housings 121 and 122 are manufactured by a casting method such as aluminum die casting, for example, and are input to the inner peripheral surface of the housing 121 via the bearing 3 with a multi-rotation sensor having the same configuration as that of the first embodiment described above. A shaft 101 is rotatably supported.

Similarly, the housing 121 is configured to drive and control the electric motor 110 using the true rotation angle θ (n) ^* output from the arithmetic processing unit 32 in the first embodiment described above as a steering angle detection value. Are input to a steering assist control device 130 including a microcomputer built in the vehicle, whereby a steering torque detection value input from a torque sensor in the steering assist control device 130, and a vehicle speed input from a vehicle speed sensor (not shown). A steering assist calculation process for generating a steering assist force based on the detected value and the detected steering angle value is performed, and a motor current command value for generating a steering assist force according to the steering torque input by the electric motor 110 is calculated. By outputting this motor current command value to the electric motor 110, the electric motor 110 generates a steering assist force, and this operation is performed. By transmitting the steering assist force to the output shaft 102 via the worm deceleration mechanism, the steering wheel can be lightly steered.

According to the second embodiment, a steering wheel (not shown) is detected by the magnetic sensors 18a and 18b of the first magnetic characteristic detection unit 18 provided in the bearing 3 in a state where the steering wheel (not shown) is in a neutral position where straight traveling is possible. Cage rotation angle θ (n) calculated based on sin θ and cos θ and the cage rotation angle calculated based on sin φ and cos φ detected by the magnetic sensors 19a and 19b of the second magnetic characteristic detection unit 19. By setting the true rotation angle θ ^* calculated based on φ (n) ′ to be 0 °, when the steering wheel is turned to the right, for example, the input shaft 101 is rotated forward and turned to the left. Assuming that the input shaft 101 sometimes reverses, as in the first embodiment described above, the steering angle is accurately detected within a range of up to 5 rotations in each of the right turn and the left turn of the steering wheel. It can be.

In this case, the axial width of the bearing 3 that rotatably supports the input shaft 101 fixed to the inner peripheral surface of the housing 121 is widened by the formation of the magnetic characteristic detection units 18 and 19. A rotation angle, that is, a steering angle can be detected in a compact and space-saving manner, and a multi-rotation position of two or more left and right rotations can be detected easily and accurately.
In the second embodiment, the case where the present invention is applied to the pinion assist type electric power steering apparatus has been described. However, the present invention is not limited to this and can be applied to other types of electric power steering apparatuses. .

  Further, in the second embodiment, the case where the arithmetic processing device 32 and the steering assist control device 130 are housed in the housing 121 has been described. However, the present invention is not limited to this. Further, the processing unit 32 may be attached, and the processing of FIG. 8 may be executed by a microcomputer that constitutes the steering assist control device 130 by omitting the arithmetic processing unit 32.

It is sectional drawing which shows the 1st Embodiment of this invention. It is a top view which shows a magnetic characteristic formation part. It is a characteristic diagram which shows the output characteristic of a magnetic characteristic detection part. It is a block diagram which shows the arithmetic processing part of 1st Embodiment. It is a characteristic diagram which shows the relationship between the rotation angle of a rotating shaft, a bearing ring rotation angle (theta), and a cage rotation angle (phi). It is a characteristic diagram which shows the relationship between a bearing ring rotation angle (theta) and a cage rotation angle (phi). FIG. 6 is a characteristic diagram showing a relationship between a rotation angle of a rotation shaft and a raceway rotation angle θ, a cage rotation angle φ, and a true rotation angle θ ^* . It is a flowchart which shows an example of the absolute angle calculation process procedure performed with a calculation processing apparatus. It is sectional drawing which shows 2nd Embodiment at the time of applying this invention to an electric power steering device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixed part, 2 ... Center opening, 3 ... Bearing, 4 ... Rotating shaft, 5 ... Fixed track ring, 6 ... Ball, 7 ... Rotating track ring, 8 ... Cage, 11 ... 1st magnetic characteristic formation part, DESCRIPTION OF SYMBOLS 12 ... 2nd magnetic characteristic formation part, 13 ... Magnetic body ring, 18 ... 1st magnetic characteristic detection part, 18a, 18b ... Magnetic sensor, 19 ... 2nd magnetic characteristic detection part, 19a, 19b ... Magnetic sensor, DESCRIPTION OF SYMBOLS 30,31 ... Converter, 32 ... Processing unit, 35 ... Non-volatile memory, 101 ... Input shaft, 102 ... Output shaft, 106 ... Torsion bar, 110 ... Electric motor, 121, 122 ... Housing, 130 ... Steering assist control apparatus

Claims (3)

A rolling bearing portion having a rolling element held by a cage between a rotating raceway and a fixed raceway, and a first magnetic property fixed to the rotating raceway and having a magnetic characteristic that periodically changes in a circumferential direction. A magnetic property forming unit, a first magnetic property detecting unit that detects the magnetic property opposite to the first magnetic property forming unit, and a magnet that is fixed to the cage and periodically changes in the circumferential direction. A second magnetic characteristic forming unit having characteristics, and a second magnetic characteristic detecting unit for detecting the magnetic characteristic opposite to the second magnetic characteristic forming unit,
When the rotation speed of the rotating raceway is set to the nearest integer equal to or greater than the rotation speed corresponding to the absolute rotation angle range to be detected, the rotation speed of the cage is set to the rotation speed of the rotating raceway / holding Rotational position detection characterized in that the rotational speed of the vessel is greater than 2 and less than 3 and is selected to be a value that is neither an integer nor a value near the integer at any integer rotation position less than or equal to the integer of the rotating raceway Bearing with part.   The rotation part and the bearing with the rotation position detection part according to claim 1 for supporting the rotation part, and the slip angle of the rotation position on the cage side of the bearing with the rotation position detection part are detected and stored, and the subsequent rotation position A rotation position reading device that calculates a multi-rotation position of the rotation unit based on a corrected slip angle obtained by correcting the reading value of the rotation position on the cage side of the bearing with the detection unit using the slip angle. Rotating device.   A steer shaft that connects a steering wheel and a steering mechanism that steers the wheel, a bearing with a rotational position detection unit according to claim 1 that supports the steering shaft, and a cage for the bearing with the rotational position detection unit. The slip angle of the side rotation position is detected and stored, and the steering shaft is adjusted based on the corrected slip angle obtained by correcting the reading value of the cage side rotation position in the bearing with the rotation position detection unit thereafter using the slip angle. A steering apparatus comprising: a rotational position reading device that calculates a rotational position.

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