JP2009530595A - Detection device for detecting angular position, electric motor, steering column, and reduction gear - Google Patents

Abstract

An apparatus for detecting an angular position, an electric motor, a steering column, and a reduction gear. The detection device 1 for detecting the angular position of the shaft 2 of the motor with respect to the non-rotating element includes a reduction device 5 having an input side connected to the shaft 2 and rotating, and an output side. Is moved over an angle smaller than 2π, a one-rotation angular position sensor 26 is arranged to measure the angle on the output side of the reduction gear 5, and the angular position sensor 27 is arranged on the input side of the reduction gear 5. The detection apparatus 1 in which is disposed.

Description

  The present invention relates to the field of angular position detection of motor shafts.

  The invention also relates to the field of electric vehicle steering columns where it is required to accurately check the angular position.

  Specifically, vehicles will use power assisted steering devices and steering column deflection angle sensors to determine wheel angles and thereby actuate brakes to correct trajectories. It is coming. Since power assist steering devices often use brushless DC motors, the switching operation must be strictly controlled and therefore the absolute angular position of the rotor must be known. Thus, the power assisted motor operates a zone orientation system to which the power assisted motor is mechanically connected. The mechanical connection between the power assisted motor and the wheel orientation system depends on the type and manufacturer of the vehicle, but at different possible positions, for example at the steering column shaft or else at the wheel orientation rack be able to. In the steering column, the gear speed is generally reduced on the order of 10 to 20 between the rotation speed of the steering column and the rotation speed of the electric motor. Therefore, the motor shaft is rotated by 10 to 20 during one rotation of the steering column. Rotate. The total number of rotations from one end swing position of the steering column to the other end swing position is on the order of 4 rotations. Therefore, it is necessary to determine the absolute angle of the motor shaft over 40 to 80 shaft rotations, and it is necessary to determine the absolute angle of the steering column over four rotations.

  Patent Document 1 discloses a first that produces an output as a function of an angular position of a steering shaft, a motor having a rotor operatively connected to the steering shaft via a gear box having a non-integer reduction ratio. A detection means and a second detection means designed to produce an output as a function of the angular position of the rotor, and the two output signals are processed so that the steering shaft A power assisted steering with processing means designed to produce an angular position signal indicative of the angular position is described. An absolute angle sensor can be provided on the motor shaft or the steering column shaft, but this is expensive because it is a multi-turn absolute sensor. Furthermore, an index can be provided on the steering shaft or the motor shaft. However, this indicator is not accurate enough.

  Patent Document 2 describes a power assisted steering in which two sensors are provided in a steering column and one sensor is provided in an electric motor. Having three sensors is expensive and requires a relatively expensive processing electronics.

  US Pat. No. 6,057,034 includes a precision sensor and proximity sensor associated with a steering column shaft that provides four times the gear reduction by means of a gear that allows the corresponding encoder to be driven more quickly. An apparatus for determining the angular position of shake is described. This device is relatively complex and does not make it possible to confirm the position of the poles of the motor.

  Patent document 4 comprises two sensor units, one of which detects the angular position in the angular segment of the full range of shake rotation and the other unit detects the shake rotation via a gear having a ratio other than 1. The deflection angle sensor for determining the absolute angular position of the wheel deflection in which the absolute angular position is detected by the difference in rotational speed detected by the two sensors is described. This document also does not make it possible to confirm the absolute angular position of the rotor of the electric drive motor.

Patent Document 5 describes an all-electric steering type vehicle shaker. This electric steering motor is linked to two reduction gears, one for wheel runout and the other for rotation over one rotation from the neutral position, ie, rotation over a total of two rotations. Is.
EP1026068 (TRW) EP141499 (Toyoda) US56464623 (Kaiser) US62448993 (Leopold Kostal) JP2005053416 (Toyoda Mach Works)

  The object of the present invention is to eliminate the drawbacks and limitations of the above document.

  An object of the present invention is to obtain an absolute angular position of a shaft of an electric steering motor and an angle of deflection of a steering wheel by using a single module. In general, the steering wheel deflection angle has a one-to-one relationship with the steering column angular position.

  The object of the present invention is to obtain the angular position in a reliable and cost effective way.

  A detection device for detecting an angular position of a shaft of a motor with respect to a non-rotating element includes a reduction device having an input side and an output side to which a shaft is connected and rotates, and the output side of the reduction device is less than 2π An angular position sensor is disposed on the input side of the speed reducer, and a one-rotation angular position sensor is disposed to measure the angle on the output side of the speed reducer. Therefore, this detection device is provided with an input angular position sensor and an output angular position sensor, and when mounted in the steering mechanism, the angular position of the motor rotor and the angular position of the wheel runout are sufficiently accurate. It is possible to provide a speed reducer that can supply two signals that can be determined by Therefore, it can be operated by the auxiliary system on the track of the vehicle. The speed reducer provided with the two sensors forms a subassembly that can be attached to a conventional type of electric steering motor.

  The reduction ratio of the reduction gear can be set between 5 and 100.

  In one form, the speed reducer includes a rolling bearing and a casing. The rolling bearing can comprise an inner ring attached to the shaft and an outer ring attached in the casing. The encoder can be supported by the inner ring and cooperate with the angular position sensor.

  In one form, the single rotation sensor is an absolute angular position sensor. Single-turn absolute angular position sensors are significantly less expensive than multi-turn absolute angular position sensors.

  In one form, the single turn sensor is mounted on an electronic circuit board supported by the casing of the speed reducer. The two sensors can be attached to the electronic circuit board. The encoder can be attached to a rolling bearing.

  In one form, the detection device includes a rolling bearing having an inner ring that is attached to the shaft and rotates, and a non-rotating outer ring.

  In one form, the speed reducer comprises at least one planetary gear train. This makes it possible to obtain a reduction ratio on the order of 5-20.

  In another form, the speed reducer comprises at least one harmonic reduction gear. This makes it possible to obtain a reduction ratio that lies between 15 and 100.

  In one form, the output side is designed with a torque corresponding to the drag torque of the reduction gear itself. The drag torque of the detector essentially consists of the drag torque of the reduction gear rolling bearing and the drag torque of the gear of the reduction gear. The drag torque of the reduction gear is very small.

  In one form, the input angular position can measure an angle of 2π. Thus, an absolute or incremental type economical angular position sensor can be used.

  In one form, the shaft is connected to an element driven by a gear transmission with a reduction ratio between 1 and 5.

  In one form, the input angular position sensor includes a multipole encoder.

  The angular position sensor can be arranged radially outside the encoder. The one-turn angular position sensor may form an axial air gap with the encoder.

  The single rotation angular position sensor may be disposed radially outside the angular position sensor.

  The sensor comprises one or more sensitive elements disposed on the opposite side of the encoder element, for example one or more Hall effect cells disposed on the opposite side of the multipole magnetic encoder ring. Can be.

  The electric motor includes a rotor, a stator, a shaft that supports the rotor, and a detection device for detecting the angular position of the shaft relative to the non-rotating element. The speed reducer includes an input side that is connected to a shaft and rotates, and an output side. The reduction gear ratio of the reduction gear is set between 5 and 100, so the output of the reduction gear moves over an angle less than 2π. Further, in order to measure the angle on the output side of the speed reducer, a one-rotation angular position sensor is disposed, and an angle position sensor is disposed on the input side of the speed reducer.

  The power auxiliary steering device can include the above-described electric motor, and the shaft driven by the electric motor is provided so as to cause the wheel of the vehicle to shake.

  According to the present invention, the speed reduction device includes a speed reduction mechanism, an input side, an output side, a rotation angle position sensor arranged to measure an angle on the output side, and an angle position sensor arranged on the input side. The reduction gear ratio of the reduction gear can be selected such that the output of the reduction gear moves over an angle that is less than 2π.

  The speed reducer may comprise a rolling bearing and casing, a rolling bearing with an inner ring attached to the shaft, an outer ring attached to the casing, and an encoder supported by the inner ring and cooperating with the angular position sensor. .

  The invention is not limited in any way and will be better understood by reading the detailed description of the embodiments given by way of example which is illustrated by the attached drawings.

  As can be seen, the angular position detection device 1 is attached to the shaft 2 of the motor. The shaft 2 supports a pinion 3 that is fixed by a key 4 and drives, for example, an additional gear of a steering column.

  The detection device 1 includes a reduction gear 5 (in this example, a harmonic reduction gear), a rolling bearing 6 and a detection portion 7.

  The speed reducer 5 (in this example, a harmonic speed reducer) is a crown gear 8 having teeth on the inner diameter surface, and meshes with the crown gear 8 in two regions located opposite to each other in the diametrical direction and is flexible in the radial direction. And a signal wave generator 10 mounted concentrically. The flexible gear 9 has an inner side surface in the axial direction. The signal wave generator 10 includes a ring 11 whose inner diameter portion is attached to the shaft 2 by a key 12 and rotates together with the shaft 2. From the ring 11, arms extend radially outward at two diametrically opposite positions. The signal wave generator 10 includes two support fingers 13 each attached to an arm. The ring, arm and finger can be united. The signal wave generator 10 has low-friction bushings 14 attached to the fingers 13 in an auxiliary manner. The bush 14 is in contact with the inner surface of the flexible gear 9, and the flexible gear 9 is deformed in the radial direction at two diametrically opposite positions so that the tooth of the crown gear 8 and the two positions are deformed. I'm biting. It is also conceivable to use a bearing instead of the bush 14. The signal wave generator 10 is keyed to the shaft 2 by a key 12.

  The rolling bearing 6 is attached to the shaft 2 between the pinion 3 and the speed reducer 5 in the axial direction. The rolling bearing 6 includes, for example, an inner ring 15 and an outer ring 16 that are sleeve-fitted on the shaft 2, rolling elements 17 (in this case, balls) that are arranged at equal intervals in the circumferential direction by a cage, and the outer ring 16. A seal flange 18 is provided which is attached to the groove and forms a narrow passage with the outer cylindrical surface of the inner ring 15 in the axial direction. Each of the inner ring 15 and the outer ring 16 has a raceway surface that is in the form of a part of an annular surface for receiving the rolling elements 17. The inner ring 15 and the outer ring 16 are deep groove type bearing rings. The rolling bearing 6 can be of a standard type that is economically manufactured in mass production.

  The detection device 1 includes a casing 19 (for example, made of a synthetic material) that surrounds the reduction gear 5 and the rolling bearing 6. In the illustrated embodiment, the casing 19 is annular and has a small-diameter axial portion 20, and the outer ring 16 of the rolling bearing 6 is fixedly attached to the inner diameter portion thereof. On the pinion 3 side, the small-diameter axial portion 20 has a short radial rim 21 extending radially inward and in contact with the front surface of the outer ring 16. A stopper is formed. The casing 19 also extends radially outward from the end of the small diameter axial portion 20 on the opposite side of the radial rim 21 in the axial direction and on a plane that includes the side end faces of the inner ring 15 and the outer ring 16 of the rolling bearing 6. A radial portion 22 having a located surface is provided. The casing 19 includes a large-diameter axial portion 23 that extends in the axial direction on the opposite side of the pinion 3 from the outer diameter portion of the radial portion 22. The crown gear 8 is fixedly attached to the large-diameter axial portion 23.

  Advantageously, the casing 19 and the crown gear 8 are made in one piece, for example by molding. The casing 19 can be made of polyamide reinforced with mineral filler.

  The detection part 7 is generally limited in the axial direction on one side by the speed reducer 5 and on the other side by the rolling bearing 6 and in the radial direction on one side by the shaft 2 and on the other side. The casing 19 is disposed in a space limited by the large-diameter axial portion 23. The detection part 7 occupies a limited angular sector (e.g. a sector on the order of 90 °) and is mounted against the inward radial surface of the radial part 22 of the casing 19 and on the side of the reduction gear 5. The electronic circuit board 24 (see FIGS. 2 and 3) is in contact with the side end face of the outer ring of the rolling bearing 16. Alternatively, the electronic circuit board can be attached to the outer ring 16 and in contact with the casing 19.

  The electronic circuit board 24 supports an electronic processing circuit 25 and two sensors 26 and 27 (eg, a magnetic sensitive type sensor). The sensor 26 is attached to the electronic circuit board 24 at a position substantially corresponding to the flexible gear in the radial direction and in the center of the electronic circuit board 24 in the circumferential direction. The sensor 27 is attached toward the substantially center of the electronic circuit board 24 in the circumferential direction and radially inward at the position of the inner edge of the electronic circuit board 24 in the radial direction. Therefore, the sensor 26 is disposed outside the sensor 27 in the radial direction. Sensors 26 and 27 can each be of the optical or magnetic type. In the following description, it is assumed that the two sensors 26 and 27 are of the magnetic sensitive type.

  The detection part 7 comprises two annular encoders 28 and 29. The encoder 28 is a multi-pole with a rectangular cross section that is mounted radially on the radial face of the flexible gear 9, for example by gluing or overmolding, and that faces the sensor 26 with a slight axial air gap. It has a ring. Since the encoder 28 is less rigid than the flexible gear 9, the sensor 26 can generate a magnetic signal following the radial deformation of the flexible gear 9.

  The encoder 28 and the gear 9 can be integrated into a single component.

  The encoder 29 is supported by the inner ring 15 of the rolling bearing 6, and a magnetic signal is generated by the sensor 27. The encoder 29 has a support 30 and an active portion 31. The support 30 extends in the direction of the reduction gear 5, a large-diameter axial portion that is sleeve-fitted to the outer peripheral surface of the inner ring 15, a radial portion that is in contact with the side end face of the inner ring 15 on the reduction gear 5 side. It has a smaller axial portion with a smaller diameter, for example, made in the form of a metal sheet bush. The active portion 31 is overmolded on the support 30 so as to surround a part of the small-diameter axial direction portion and the large-diameter axial direction portion of the support 30, and is an axis facing the sensor 27 with a small radial air gap. It has a directional outer surface, for example, made as a plastferrite type.

  In the illustrated embodiment, the rolling bearing 6 does not include a seal flange on the encoder 29 side. However, a suitably shaped friction seal or flange that cooperates with a portion of the encoder 29 can be provided.

  Thus, the detection part 7 receives two sensors and an output signal from the sensors and, for example, via a wired or wireless link (not shown), an item of information representing the absolute angular position of the axis 2 and a shake And an electronic circuit board 25 of the same type that supports an electronic circuit capable of transmitting an item of information about the angle to the outside. The electronic circuit board 25 can transmit the output signals from the sensor 26 and sensor 27 after simple formatting, or alternatively, on the one hand, based on the information supplied by the sensor 27, on the other hand, As a function of the vehicle wheel deflection angle as a function of the output signal of the sensor 26 and the output signal of the sensor 27, processing can be performed that allows the absolute angular position of the shaft 2 of the motor to be determined with the desired accuracy.

  Thus, the detection device 1 comprises a single rolling bearing, a speed reducer, two encoders, two sensors and a single electronic circuit board that supports the sensors (this is specifically economical and compact) Can be provided. Moreover, the detection apparatus 1 forms the subassembly easily assembled in the one end part of the axis | shaft 2 of an electric motor between a steering column drive pinion and the casing (not shown) of an electric motor, for example. Therefore, in the prior art, a single, compact system is used instead of a system distributed over the steering column and distributed over the power-assisted steering motor.

  During operation, the motor shaft 2 can rotate and drive the pinion 3 to operate the wheel run-out device. This is because the motor shaft 2 is driven by the angular movement of the motor shaft 2 and the steering column shaft. This is because the gear ratio is mechanically connected to the wheel directing system so that the reduction ratio with respect to the angular movement is on the order of 10 to 20. The inner ring 15 of the rolling bearing 6 and thus the encoder 29 are driven at the same speed as the shaft 2. Therefore, the angular movement of the shaft 2 is detected by the sensor 27, transmitted to the electronic circuit 25, transmitted to the external member, and appropriately processed. The signal wave generator 10 of the reduction gear 5 is also driven at the same rotational speed as that of the shaft 2, and the shaft 2 rotates the flexible gear 9 at a reduction ratio of 5 to 100, preferably on the order of 40 to 80. In other words, the flexible gear 9 and the encoder 28 move at an angle of 1 ° with respect to the movement angle 40 to 80 ° of the shaft 2. The angular movement of the encoder 28 and the flexible gear 9 is detected by the sensor 26, transmitted to the electronic circuit 25, transmitted to the external member, and appropriately processed.

  In order to limit the angular movement of the flexible gear 9 and the encoder 28 to a rotation smaller than one rotation, the reduction ratio of the reduction gear 5 is changed from the one stop of the steering column to the reduction ratio of the shaft 2 to the steering column. It is designed to exceed or be equal to the value multiplied by the number of revolutions up to the stop (that is, from the end position of the leftward deflection of the vehicle wheel to the end position of the rightward deflection). This ensures that the encoder 28 has a rotation range below 360 °. Thus, a one-turn type encoder 28 and sensor 26 can be used, which is clearly more economical than a multi-turn sensor. Even though sensor 26 and encoder 28 provide a less accurate signal, the precise angular position of axis 2 is provided by sensor 27 and encoder 29 so that the resolution of sensor 26 and encoder 28 is relatively Can be lowered. Since the gear reduction is performed by the reduction gear 5, it is possible to determine the angular position of the steering column with a very high accuracy of the order of 0.1 °.

  The encoder 28 is a type in which the poles alternate in the circumferential direction, or a 4-pole type having the exterior N pole and the built-in S pole at 180 ° and the built-in N pole and the exterior S pole at 180 °. be able to. The magnetic field sensed by the sensor changes according to the angular position and the radial position of the encoder 28 due to the radial deformation of the flexible gear 9.

  In order to control the electric motor 2 (which can be a brushless DC type), it is desirable to know exactly the angular position of the rotor and thus the pole of the shaft 2. The sensor 27 and encoder 29 are of the multi-rotation type with high resolution or otherwise providing an absolute angle.

  In the illustrated embodiment, the casing 19 is designed to be non-rotating, for example, such that the rotation is fixedly attached to the casing of the motor, but one of the encoders is linked to the inner ring of the rolling bearing. The other is linked to the flexible gear of the reduction gear. As an alternative, the encoder 29 can be mounted directly on the axial annular part 11 of the signal wave generator 10, or directly on the shaft 2, and thus a standard type rolling element with two standard type sealing elements. Bearings can be used. This results in a reduction gear that the crown gear can be designed to support the sensor, thus ensuring concentricity between the crown gear and the motor shaft at the rolling bearing.

  In FIG. 1, for the sake of clarity, the casing 32 and the steering column 33 of the electric motor are indicated by broken lines.

  In accordance with the present invention, a user is attached as a subassembly to a motor shaft of a power-assisted steering or all-electric steering and provides both a signal representing the exact angular position of the motor shaft and a signal representing the angle of wheel runout. You will have a very compact and economical device with an electronic circuit board. Only two sensors are sufficient to supply these data. In addition, it is possible to dispense with, for example, rolling bearings for the steering column or other additional detection systems arranged on the steering rack.

  It is also possible to provide a planetary type speed reducer instead of a harmonized speed reducer without departing from the scope of the present invention.

It is an axial sectional view of an angular position detection device. FIG. 2 is an exploded perspective view of the apparatus of FIG. 1. FIG. 2 is a side elevational view of the apparatus of FIG.

Claims (13)

  The detection device (1) for detecting the angular position of the shaft (2) of the motor with respect to the non-rotating element includes a reduction device (5) having an input side connected to the shaft (2) and rotating, and an output side. A one-turn angular position sensor (26) is disposed on the output side of the speed reducer to move over an angle smaller than 2π and measures the angle on the output side of the speed reducer, and the input of the speed reducer An angular position sensor (27) is disposed on the side.   The detection device according to claim 1, wherein a reduction ratio of the reduction gear is set between 5 and 100.   The detection device according to claim 1 or 2, wherein the single rotation sensor (26) is an absolute angular position sensor.   The one-turn sensor (26) is mounted on an electronic circuit board supported by a casing (19) of the speed reducer, according to one of claims 1, 2 and 3. Detection device.   The detection device according to any one of claims 1 to 4, wherein the reduction device includes at least one planetary gear train or at least one harmonic reduction gear.   The speed reducer (5) includes a rolling bearing (6) and a casing (19), and the rolling bearing (6) is attached to an inner ring (15) and a casing (19) attached to the shaft (2). An encoder (29) comprising an outer ring (16) and supported by an inner ring (15) cooperates with an angular position sensor (27). The detection device according to one.   The angular position sensor (27) is located radially outside the encoder (29) and the one-turn angular position sensor (26) has an axial air gap with the encoder (28); The detection apparatus according to any one of claims 1 to 6, wherein at least one of the two conditions is provided.   9. The detection device according to claim 1, wherein the one-rotation angular position sensor (26) is arranged outside the angular position sensor (27) in the radial direction. .   The detection device according to any one of claims 1 to 8, wherein the angular position sensor (27) is capable of measuring an angle of 2π.   An electric motor comprising a rotor, a stator, and the detection device according to any one of claims 1 to 9, wherein the rotor is connected to an input side of a speed reducer (5). An electric motor characterized by that.   A power auxiliary steering apparatus comprising: the electric motor according to claim 10; and a shaft (2) driven by the electric motor to steer the wheels of the vehicle.   A speed reduction device (5) comprising a speed reduction mechanism, an input side and an output side, comprising a one-rotation angular position sensor (26) arranged to measure an angle on the output side, and the speed reduction ratio of the speed reduction device is: The speed reducer (5), wherein the output side of the speed reducer is set to move over an angle smaller than 2π, and an angular position sensor (27) is disposed on the input side of the speed reducer.   The speed reducer according to claim 12, comprising a single rolling bearing.

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