JP2006170805A - Rotation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the magnitude of an output change of an active sensor 5c by reducing the ratio of magnetic flux which does not change regardless of the rotation of a tone wheel 4. <P>SOLUTION: At one end in the magnetization direction of a permanent magnet 17 constituting the sensor 5c, a part adjacent to a magnetic detection element 18 is covered with a magnetic shielding member 19, thereby preventing magnetic flux emanating from an external face of the permanent magnet 17 from reaching the tone wheel 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The rotation detection device according to the present invention is incorporated in, for example, a rolling bearing unit for supporting a wheel of an automobile and used for detecting the rotation speed or the rotation amount (rotation angle) of the wheel of the automobile. Further, it is incorporated in a movable part of various machine devices such as a machine tool and used for obtaining the moving speed or moving amount of the movable part.

  A rolling bearing unit is used to rotatably support the wheels of the automobile with respect to the suspension system. Further, in order to control the anti-lock brake system (ABS) and the traction control system (TCS), it is necessary to detect the rotational speed of the wheel. For this reason, in recent years, it has been possible to support the wheel rotatably with respect to the suspension device and to detect the rotational speed of the wheel by a rolling bearing unit with a rotation detection device in which a rotation detection device is incorporated in the rolling bearing unit. It has become widely practiced.

  4-5 has shown what was described in patent document 1 as a 1st example of the conventional structure of the rolling bearing unit with a rotation detection apparatus used for such a purpose. This rolling bearing unit with a rotation detection device rotatably supports a hub 2 and an inner ring 3 that are rotating members on an inner diameter side of an outer ring 1 that is a stationary member that does not rotate. The rotational speed of the tone wheel 4 fixed to a part of the hub 2 can be detected by a sensor 5 supported on the outer ring 1.

  That is, double row outer ring raceways 6 and 6 are formed on the inner peripheral surface of the outer ring 1, and a coupling flange 7 is formed on the outer peripheral surface. On the other hand, a mounting flange 8 is formed on a part of the outer peripheral surface of the hub 2 protruding from the outer end opening of the outer ring 1. Inner ring raceways 9 and 9 are formed on the outer peripheral surface of the intermediate portion of the hub 2 and the outer peripheral surface of the inner ring 3 that is fitted and fixed to the inner end portion of the hub 2. A plurality of rolling elements 10 and 10 are provided between the inner ring raceways 9 and 9 and the outer ring raceways 6 and 6, respectively, so as to be freely rollable. In the case of a rolling bearing unit for supporting a heavy automobile wheel, a tapered roller may be used as a rolling element instead of a ball as shown.

  In order to incorporate the rotation detection device into the rolling bearing unit as described above, the tone wheel 4 is fitted and fixed to the inner end of the inner ring 3. In the case of the illustrated example, the tone wheel 4 is formed in an annular shape with an L-shaped cross section by performing plastic working on a magnetic metal plate such as a mild steel plate. Then, by forming a large number of through holes in the ring portion 11 of the tone wheel 4 at equal intervals in the circumferential direction, the magnetic characteristics of the ring portion are changed alternately and at equal intervals in the circumferential direction. I am letting. A synthetic resin sensor holder 13 that embeds and supports the sensor 5 is supported and fixed to a cover 12 that is fitted and fixed to the inner end opening of the outer ring 1. In this state, the detection portion of the sensor 5 is opposed to the inner surface, which is the detection surface, of the annular portion 11 constituting the tone wheel 4 in the axial direction via a minute gap.

  When the rolling bearing unit with a rotation detecting device configured as described above is used, the coupling flange 7 provided on the outer circumferential surface of the outer ring 1 is coupled and fixed to the suspension device, and the mounting flange 8 provided on the outer circumferential surface of the hub 2. The wheel is supported and fixed. In this state, when the tone wheel 4 rotates together with the wheel, the frequency of the output signal of the sensor 5 changes according to the rotational speed of the tone wheel 4. Therefore, if the output signal of the sensor 5 is sent to a controller (not shown), ABS and TCS can be appropriately controlled.

  In Patent Document 2, as shown in FIGS. 6 to 7, a tone wheel 4a is fitted and fixed to the outer peripheral surface of the inner ring 3 which is a rotating member, and a sensor 5a is attached to an axially intermediate portion of the outer ring 1a which is a stationary member. Is a rolling bearing unit with a rotation detection device, in which the outer ring 1a is supported and fixed in a state of passing through the outer ring 1a in the radial direction. In the case of the second example of this conventional structure, gear-shaped irregularities are formed on the outer peripheral surface which is the detected surface of the tone wheel 4a. And the detection part of the said sensor 5a is made to oppose to this outer peripheral surface in the radial direction through a micro clearance gap.

Furthermore, in Japanese Patent Application No. 2004-279155, a combination of a tone wheel supported and fixed to a rotating member and a sensor supported and fixed to a stationary member, the relative displacement amount between these rotating member and stationary member, An invention relating to a load measuring device for obtaining a load applied between these two members is described.
8 to 9 show a first example of such a structure according to the prior invention. In the case of the first example of the prior invention, a plurality of through holes 14a, 14b each having a slit shape are alternately formed on the tone wheel 4b made of a magnetic material that is externally fitted and fixed to the intermediate portion of the hub 2. Yes. These through holes 14a and 14b are inclined with respect to the direction of the central axis of the tone wheel 4b. Further, the inclination directions are opposite to each other between the through holes 14a and 14b adjacent in the circumferential direction. Further, the pitch between the through holes 14a and 14b adjacent in the circumferential direction alternately repeats the magnitude. Further, the detection portion of the sensor 5b provided in a state of passing through the intermediate portion of the outer ring 1 in the radial direction is made to face and face the outer peripheral surface of the tone wheel 4b, which is the detection surface.

  In the case of the first example of the load measuring device according to the present invention configured as described above, a pattern in which the detection signal of the sensor 5b changes when the hub 2 and the outer ring 1 are relatively displaced in the axial direction based on an axial load. Changes. Therefore, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained based on the change in the pattern. Note that the period in which the detection signal changes based on the through holes 14a and 14a (14b and 14b) inclined in the same direction does not change regardless of the relative displacement. Therefore, the rotational speed of the hub 2 can be obtained based on this cycle.

  Next, FIG. 10 shows a tone wheel 4c incorporated in the second example of the structure according to the previous invention. The tone wheel 4c is formed in a cylindrical shape by a magnetic metal plate, and slit-shaped through holes 14c and 14d are respectively formed in one half portion and the other half portion in the width direction, and the central axis of the tone wheel 4c. Are formed at equal intervals with respect to the circumferential direction. The inclination direction of the through holes 14c, 14c in the half half of the width direction is opposite to the inclination direction of the through holes 14d, 14d in the other half part. On the outer peripheral surface of such a tone wheel 4c, the detection portions of a pair of sensors arranged in a state of being separated in the axial direction are made to face each other.

  In the case of the second example of the load measuring device according to the present invention that includes the tone wheel 4c as described above, when the hub and the outer ring are relatively displaced in the axial direction based on the axial load, the detection of the pair of sensors is performed. The signal is out of phase. Therefore, based on the magnitude of the deviation, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained. The rotational speed of the hub is obtained based on the detection signal of any sensor.

  Next, FIGS. 11 to 12 show a third example of the structure according to the previous invention. In the case of the third example of the prior invention, the base end portion of the tone wheel 4d as shown in FIG. 12 is externally fitted to the inner end portion of the inner ring 3 which is externally fitted and fixed to the inner end portion of the hub 2. The tone wheel 4d is supported and fixed to the hub 2 concentrically with the hub 2. The tone wheel 4d is made of a magnetic metal plate, and has slits-shaped through holes 14e and 14e formed at equal intervals in the circumferential direction in a cylindrical portion provided in the front half. Yes. In addition, a pair of sensors are held in an axially separated state in a sensor holder 16 supported by a cover 15 fitted and fixed to the inner end of the outer ring 1. And the detection part of these both sensors is made to oppose and adjoin to the internal peripheral surface of the said tone wheel 4d.

  Also in the case of the third example of the load measuring device of the prior invention as described above, when the hub 2 and the outer ring 1 are relatively displaced in the axial direction based on the axial load, the detection signals of the pair of sensors are out of phase. Therefore, based on the magnitude of the deviation, the magnitude of the relative displacement and further the magnitude of the axial load can be obtained. The rotational speed of the hub 2 is obtained based on the detection signal of any sensor.

  Next, FIG. 13 shows a tone wheel 4e incorporated in the fourth example of the structure according to the previous invention. The tone wheel 4e is formed in an annular shape from a magnetic metal plate, and trapezoidal through holes 14f and 14f, each of which has a larger width in the circumferential direction toward the outer side in the radial direction, are equally spaced in the circumferential direction. Forming. The detection part of the sensor is placed in close proximity to one side surface in the axial direction of such a tone wheel 4e.

  In the case of the fourth example of the load measuring device according to the present invention configured to include the tone wheel 4e as described above, when the hub and the outer ring are relatively displaced in the radial direction based on the radial load, the duty of the detection signal of the sensor is determined. The ratio changes. Therefore, the magnitude of the relative displacement and further the magnitude of the radial load can be obtained based on the duty ratio. The rotational speed of the hub is determined based on the period of the detection signal of the sensor.

  For example, as the magnetic detection type sensors 5 and 5a constituting the rotation detection device incorporated in the rolling bearing unit as shown in FIGS. 4 to 7, the passive type and the active type have been widely known. ing. Among these sensors, the passive type sensor induces a voltage in the coil in response to a change in magnetic flux, and obtains this change in voltage as an output signal. In the active type, the characteristics of magnetic detection elements such as a Hall element and a magnetoresistive element are changed in response to a change in magnetic flux, and an output signal corresponding to the change in the characteristics is obtained.

  Of these, the active type sensor can be configured smaller than the passive type sensor, and can obtain a stable output regardless of the rotational speed of the tone wheel. . The active type sensor includes a permanent magnet and a magnetic detection element that allows a magnetic flux supplied from the permanent magnet to pass therethrough and changes its characteristics in accordance with the density of the passing magnetic flux. When the tone wheel rotates with such an active sensor facing the detected surface of the magnetic tone wheel, the distance between the magnetic detecting element and the ferromagnetic portion of the detected surface is as follows. In a shortened state, the density of the magnetic flux passing through this magnetic detection element increases. On the other hand, the density of the magnetic flux passing through the magnetic detection element is lowered in a state where the distance between the magnetic detection element and the ferromagnetic portion of the detected surface is increased. As described above, the characteristics of the magnetic detection element change in accordance with the density of the passing magnetic flux. Therefore, if the change in the characteristic is converted into an electric signal by an appropriate processing circuit such as a bridge circuit, the tone wheel An output signal corresponding to the rotation speed of can be obtained.

  By the way, there are a method for obtaining the rotational speed of the tone wheel based on the output change of the sensor, a method for obtaining it based on the cycle of change, and a method for obtaining it based on the frequency of change. Of these, in order to employ a method that is determined in accordance with the period of change and increase the responsiveness relating to the detection of the rotational speed, it is necessary to shorten the pitch at which the magnetic characteristics of the detected surface of the tone wheel change. In addition, the pitch needs to be shortened when a method for obtaining the frequency is adopted to increase the accuracy (resolution) related to the detection of the rotational speed. In recent years, there has been an increasing demand for higher responsiveness and detection accuracy in response to higher performance of ABS and TCS.

  However, if the pitch of the active sensor is the same as that of the conventional structure and the pitch is shortened, the output change of the sensor is reduced, and the rotational speed may not be detected accurately. This is because the proportion of the magnetic flux supplied from the permanent magnet built in the active sensor increases without passing through the magnetic detection element. That is, as indicated by an arrow in FIG. 14, a part of the magnetic flux flowing between the N pole and the S pole of the permanent magnet 17 is one side of the magnetic detection element 18 (upper surface in FIG. 14). It goes in and out even at the outer peripheral surface portion of the end portion on the side abutted against. In this manner, the amount of magnetic flux that enters and exits from the outer peripheral surface of the end portion of the permanent magnet 17 and flows to the tone wheel 4 does not change much regardless of the rotation of the tone wheel 4. As a result, regardless of the rotation of the tone wheel 4, the amount of change in the magnetic flux passing through the magnetic detection element 18 is reduced, and the degree of change in the characteristics of the magnetic detection element 18 is reduced. It becomes difficult to ensure the reliability of rotation speed detection. The decrease in reliability due to such a cause becomes more remarkable as the pitch is shortened.

  In particular, as in the previous invention shown in FIGS. 8 to 13 described above, the structure is such that the displacement between the sensor and the tone wheel constituting the rotation detection device is obtained and the load applied to the rolling bearing unit is obtained based on this displacement. Further, it is necessary to accurately grasp the circumferential position (the position of the circumferential edge of the through hole) of the portion where the magnetic characteristics of the tone wheel change based on the detection signal of the sensor. Therefore, as shown in FIG. 14 described above, the presence of magnetic flux entering and exiting the outer peripheral surface of the permanent magnet 17 makes it difficult to ensure the reliability of detecting the rotational speed of the tone wheel 4. Become. That is, if the circumferential position of the boundary portion where the magnetic characteristics change cannot be accurately grasped, the measurement accuracy of the displacement and load deteriorates.

Japanese Utility Model Publication No. 7-31539 JP-A-8-94657

  In view of the above-described circumstances, the rotation detection device of the present invention suppresses the ratio of magnetic flux that does not change regardless of the rotation of the tone wheel when an active sensor is used. It was invented to realize a structure that can ensure the thickness.

Each of the rotation detection devices of the present invention includes a tone wheel and a sensor.
Of these, the tone wheel has a surface to be detected in which the magnetic characteristics are alternately changed in the circumferential direction. And it is supported by the rotating member in a state where the center of the detected surface and the center of rotation coincide.
The sensor is supported by a non-rotating stationary member provided adjacent to the rotating member in a state where the detecting portion faces the detection surface of the tone wheel, and the rotation of the tone wheel is performed. Change the output signal. The sensor passes through a permanent magnet magnetized in a direction in which the sensor faces the detected surface of the tone wheel and a magnetic flux supplied from the permanent magnet, and corresponds to the density of the magnetic flux passing therethrough. And a magnetic detection element that changes the characteristics.

In particular, in the rotation detection device according to the first aspect, the periphery of the portion adjacent to the magnetic detection element at one end portion in the magnetization direction of the permanent magnet is covered with the magnetic shielding member.
Further, in the rotation detecting device according to claim 2, a magnetic hole is formed between the magnetic detecting element and the tone wheel in a portion of the magnetic detecting element serving as the detecting portion. A magnetic shielding plate made of material is arranged.

  In the case of the rotation detection device of the present invention configured as described above, magnetic flux entering and exiting from the outer peripheral surface of the end of the permanent magnet can be prevented from flowing into the tone wheel, and the magnetic detection accompanying the rotation of the tone wheel can be prevented. The amount of change in magnetic flux passing through the element can be increased. As a result, the output signal of the sensor is greatly changed, and values relating to the rotation of the rotating member, such as the rotation speed and rotation angle of the rotating member, can be accurately obtained.

  That is, in the case of the rotation detection device according to claim 1, the magnetic flux entering and exiting from the outer peripheral surface of one end of the permanent magnet provided in a state where the end surface of the magnetizing direction abuts against one surface of the magnetic detection element It does not flow to the detected surface of the tone wheel by being blocked by the magnetic shielding member provided in the covering state. By such a magnetic shielding effect by the magnetic shielding member, the range through which the magnetic flux entering and exiting the permanent magnet can be limited between the detection portion of the magnetic detection element and the detection surface of the tone wheel. For this reason, even if the shape of the part where the magnetic properties change, such as the through-holes and protrusions formed in this tone wheel, is minute (the change pitch is small), the circumferential direction of the boundary part where the magnetic properties change The position can be detected with high accuracy.

  Further, in the case of the rotation detecting device according to claim 2, the magnetic flux entering and exiting from the outer peripheral surface of one end of the permanent magnet provided in a state where the end surface of the magnetizing direction abuts against one surface of the magnetic detecting element is generated between the sensor and the tone wheel. It does not flow to the detected surface of the tone wheel by being shielded by the magnetic shielding plate having a through hole disposed therebetween. The magnetic flux that flows out from the permanent magnet to the surface to be detected of the tone wheel is only the magnetic flux that enters and exits from the end face in the magnetization direction of the permanent magnet and passes through the through hole. For this reason, by properly regulating the size of the through hole, the shape of the part where the magnetic properties change, such as the through hole and convex part formed in the tone wheel, is very small (change pitch is small) However, it is possible to accurately detect the circumferential position of the boundary portion where the magnetic characteristics change.

In carrying out the present invention, preferably, as described in claim 3, the pitch or phase at which the magnetic characteristic of the detected surface of the encoder changes in the circumferential direction is continuously set in the width direction of the detected surface. To change. An arithmetic unit is provided that calculates a relative displacement amount between the rotating member and the stationary member based on a pattern in which an output signal of the sensor having the detection unit opposed to the detection surface changes.
By adopting such a configuration, the relative displacement amount between the rotating member and the stationary member can be obtained without using a highly accurate displacement sensor.
Further, when the invention described in claim 3 as described above is carried out, preferably, as described in claim 4, the calculator is based on a relative displacement amount between the rotating member and the stationary member. Thus, a function of calculating a load acting between these two members is provided.
If such a structure is employ | adopted, the load which acts between a rotating member and a stationary member is calculated | required, without using a highly accurate load sensor.

  1 and 2 show a first embodiment of the present invention corresponding to claim 1. The feature of this embodiment is that the magnetic flux emitted from the permanent magnet 17 constituting the sensor 5c in combination with the magnetic detection element 18 is opposed to the detection portion of the magnetic detection element 18 in the detected surface of the tone wheel 4. It is in the point that it flows only to the part which is doing. In other words, a part of the magnetic flux emitted from the permanent magnet 17 is prevented from flowing to a portion other than the portion of the detected surface of the tone wheel 4 where the detection portion of the magnetic detection element 18 is facing, In this structure, the change in the magnetic flux flowing through the magnetic detection element 18 due to the rotation of the tone wheel 4 becomes remarkable. Since the structure and operation of other parts are the same as those of the conventional structure shown in FIGS. 4 to 7 or the structure of the prior invention shown in FIGS. In the following, the description will focus on the features of this embodiment.

  In the case of the present embodiment, one end surface (N-pole side end surface) in the magnetizing direction of the permanent magnet 17 formed in a columnar shape and magnetized in the axial direction is opposite to the detection portion of the magnetic detection element 18. It abuts against the side surface (the back part of the detector). And the one end surface thru | or intermediate part of the said permanent magnet 17 which is a part adjacent to this abutting part are covered over the perimeter by the magnetic shielding member 19 formed in the cylindrical shape with magnetic metal plates, such as mild steel. Yes.

  In the case of the present embodiment in which such a magnetic shielding member 19 is provided, the magnetic flux emitted from the outer peripheral surface of one end (the lower end of FIGS. 1 and 2) of the permanent magnet 17 is provided in a state of covering the outer peripheral surface of the one end. It does not flow to the detected surface of the tone wheel 4 by being blocked by the magnetic shielding member 19. That is, the magnetic flux emitted from the outer peripheral surface of one end of the permanent magnet 17 is guided to the magnetic shielding member 19 and sent to the south pole side of the permanent magnet 17. Due to the magnetic shielding effect of the magnetic shielding member 19, the range through which the magnetic flux entering and exiting the permanent magnet 17 passes between the detection portion of the magnetic detection element 18 and the detected surface of the tone wheel 4. Can be limited. For this reason, even when the shape of the through hole 14 formed in the tone wheel 4 is very small (the change pitch is small), the circumferential edge of the through hole 14 is a boundary portion where the magnetic characteristics change. The circumferential position can be detected with high accuracy.

  Various conventionally known elements such as a Hall element, an MR element, and a GMR element can be used as the magnetic detection element 18 incorporated in the sensor used when the present invention is implemented. A differential sensor is preferably used. Further, the shape of the permanent magnet 17 combined with such a magnetic detection element 18 is not necessarily a cylindrical shape, and for example, a quadrangular prism shape or a conical shape can be adopted. Accordingly, the shape and size of the magnetic shielding member 19 are the same as the shape and size of the permanent magnet 17, the shape and size of the through hole 14 formed in the tone wheel 4, or the position of the magnetic detection element 18. Select appropriately according to the dimensions.

  Further, in order to change the output form of the sensor 5c, the shape, number and size of the through holes 14 provided in the tone wheel 4 are changed. In this way, changing the shape, number, and dimensions of the through-holes 14 can be easily performed as compared to changing the magnetization range with an encoder made of a permanent magnet. Further, if an anisotropic magnet having a magnetic material oriented in the magnetization direction is used as the permanent magnet 17 incorporated in the sensor 5c, the amount of magnetic flux entering and exiting from the end face in the magnetization direction is increased (entering and exiting from the circumferential surface). (Suppressing the amount of magnetic flux to be reduced) and further improving the detection accuracy with respect to the circumferential position of the circumferential edge of the through hole 14 (making the spot diameter representing the detection range of the sensor 5c smaller). it can.

  FIG. 3 shows a second embodiment of the present invention corresponding to claim 2. Also in this embodiment, the magnetic flux emitted from the permanent magnet 17 constituting the sensor 5d in combination with the magnetic detection element 18 is opposed to the detection portion of the magnetic detection element 18 on the detected surface of the tone wheel 4. The point is that it flows only to the part where it is.

  In the case of the present embodiment, a magnetic shielding plate 20 made of a magnetic material such as a mild steel plate is disposed between the magnetic detection element 18 and the tone wheel 4. The size of the outer peripheral edge of the magnetic shielding plate 20 is larger than the size of the outer peripheral edge of the magnetic detection element 18. Further, a through hole 21 is formed in the central portion of the magnetic shielding plate 20 at a portion aligned with the detection portion of the magnetic detection element 18.

  In the present embodiment in which such a magnetic shielding plate 20 is provided, the outer peripheral surface of one end portion of the permanent magnet 17 provided in a state where the end surface in the magnetization direction (the end surface on the N pole side) abuts against one surface of the magnetic detection element 18. The magnetic flux emitted from the magnetic shield plate 20 is blocked by the magnetic shield plate 20 and does not flow to the detected surface of the tone wheel 4. Magnetic flux that flows out from the permanent magnet 17 and flows to the detected surface of the tone wheel 4 exits from the end surface of the permanent magnet 17 in the magnetization direction and is formed on the magnetic shielding plate 20 as shown by arrows in FIG. Only the magnetic flux that has passed through the through-hole 21 is obtained. For this reason, even if the through-hole 14 formed in the tone wheel 4 is very small by appropriately regulating the size of the through-hole 21 so as to match the detection portion of the magnetic detection element 18, the magnetic It is possible to accurately detect the circumferential position of the circumferential edge of the through hole 14, which is a boundary portion where characteristics change.

The principal part expansion perspective view which shows Example 1 of this invention. The schematic diagram for demonstrating the reason a magnetic flux can be concentrated on the principal part of the to-be-detected surfaces of a tone wheel. The figure similar to FIG. 2 which shows Example 2 of this invention. Sectional drawing which shows the 1st example of a conventional structure. The figure seen from the right side of FIG. Sectional drawing which shows the 2nd example of a conventional structure. The figure which cut | disconnected a part and was seen from the right side of FIG. Sectional drawing which shows the 1st example of the structure which concerns on a prior invention. The perspective view of the tone wheel integrated in this 1st example. The perspective view of the tone wheel incorporated in the 2nd example of the structure concerning a prior invention. Sectional drawing which shows the 3rd example of the structure which concerns on a prior invention. Sectional drawing of the tone wheel incorporated in this 3rd example. The side view which looked at the tone wheel integrated in the 4th example of the structure concerning a prior invention from the axial direction. The schematic diagram for demonstrating why the output change of an active type sensor becomes small by shortening the pitch in which the magnetic characteristic of the to-be-detected surface of a tone wheel changes.

DESCRIPTION OF SYMBOLS 1, 1a Outer ring 2 Hub 3 Inner ring 4, 4a-4e Tone wheel 5, 5a, 5b, 5c, 5d Sensor 6 Outer ring track 7 Coupling flange 8 Mounting flange 9 Inner ring track 10 Rolling body 11 Circular ring part 12 Cover 13 Sensor holder 14 , 14a to 14f Through-hole 15 Cover 16 Sensor holder 17 Permanent magnet 18 Magnetic detection element 19 Magnetic shielding member 20 Magnetic shielding plate 21 Through-hole

Claims (4)

  A tone wheel that has a surface to be detected whose magnetic characteristics are alternately changed in the circumferential direction, and that is supported by the rotating member in a state in which the center of the surface to be detected coincides with the center of rotation; A sensor that is supported by a non-rotating stationary member provided adjacent to the rotating member with the detecting portion facing the detecting surface, and that changes an output signal in accordance with the rotation of the tone wheel. The sensor passes through a permanent magnet that is magnetized in a direction in which the sensor faces the detected surface of the tone wheel, and a magnetic flux supplied from the permanent magnet, and has characteristics corresponding to the density of the magnetic flux that passes through the permanent magnet. In a rotation detection device comprising a magnetic detection element that changes the magnetic field, the periphery of a portion adjacent to the magnetic detection element at one end in the magnetization direction of the permanent magnet is covered with a magnetic shielding member. Rotation detecting apparatus according to claim.   A tone wheel that has a surface to be detected whose magnetic characteristics are alternately changed in the circumferential direction, and that is supported by the rotating member in a state in which the center of the surface to be detected coincides with the center of rotation; A sensor that is supported by a non-rotating stationary member provided adjacent to the rotating member with the detecting portion facing the detecting surface, and that changes an output signal in accordance with the rotation of the tone wheel. The sensor passes through a permanent magnet that is magnetized in a direction in which the sensor faces the detected surface of the tone wheel, and a magnetic flux supplied from the permanent magnet, and has characteristics corresponding to the density of the magnetic flux that passes through the permanent magnet. In a rotation detection device comprising a magnetic detection element that changes the magnetic field, a portion of the magnetic detection element that is to be the detection unit is passed between the magnetic detection element and the tone wheel. To form a rotation detecting device, characterized in that placing the magnetic material made of a magnetic shielding plate.   The pitch or phase at which the magnetic characteristics of the detected surface of the encoder change in the circumferential direction is continuously changing in the width direction of the detected surface, and the output of the sensor with the detector facing this detected surface The rotation detection device according to claim 1, further comprising an arithmetic unit that calculates a relative displacement amount between the rotating member and the stationary member based on a pattern in which the signal changes.   The rotation detector according to claim 3, wherein the computing unit has a function of calculating a load acting between the two members based on a relative displacement amount between the rotating member and the stationary member.

Images