JP2007263872A - Steering angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering angle detector capable of precisely detecting a rotational angle of a rotary shaft over the entire steering angle range and precisely detecting a steering angle of a vehicle with simple constitution. <P>SOLUTION: In the steering angle detector obtaining the rotational angle over a plurality of rotations of a steering shaft 3 to detect the steering angle of a vehicle steered by transmitting rotation of the steering shaft 3 according to an operation of a steering wheel 30 to a steering mechanism 1 and by transmitting an operation of the steering mechanism 1 to wheels 14, 14 for steering connected via a tie rod 12 and changing directions of the wheels 14, 14 to perform steering, a relative angular displacement of the tie rod 12 with respect to the front wheel 14 is detected by an angular displacement sensor 6 so as to determine a region corresponding to the number of rotations from a neutral position to the right or left in which the steering shaft 3 is present. The rotational angle of the steering shaft 3 in the determined region is acquired by a rotational angle sensor to calculate the steering angle in the entire steering angle range. Accordingly, the steering angle can be precisely detected over the entire steering angle range with the simple constitution. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a steering angle detection device capable of accurately detecting a steering angle of a vehicle with a simple configuration.

  Steering of a vehicle transmits a rotation operation of a steering wheel, which is a steering member, to a steering mechanism via a steering shaft connected to the steering wheel, and changes the direction of the steering wheel by the operation of the steering mechanism. Is done. The steering angle (hereinafter referred to as the steering angle), which is the direction of the steering wheel that changes in accordance with the operation of the steering wheel, is important information for various types of control of the vehicle. Hereinafter, it is desired to detect with high accuracy over the entire steering angle range.

  The steering angle of a vehicle is generally obtained by detecting the rotation angle of a steering shaft (rotating shaft) that rotates a plurality of times according to the operation of the steering wheel over the entire steering angle range. The steering wheel is normally configured to rotate 3 to 5 in order to steer over the entire steering angle range, and in order to detect the rotation angle of the steering shaft over the entire steering angle range, A rotation angle sensor capable of detecting an angle in the range of 1800 ° is required. The rotation angle sensor includes, for example, a speed reducer for converting a plurality of rotations into one rotation, and is configured to detect a rotation angle within one rotation after the conversion, and includes a sensor main body and peripheral members. There is a problem that the configuration becomes complicated.

In order to solve this problem, a steering angle detection device that detects the steering angle by detecting the rotation angle of the steering shaft over the entire steering angle range with a simple configuration has been proposed (for example, patents). Reference 1 and Patent Reference 2).
JP 2005-114676 A JP 2003-307418 A

  The steering angle detection device of Patent Document 1 is an electric power steering device configured to transmit the rotational force of a steering assist motor to a steering shaft via a worm and a worm wheel. A spiral groove is engraved, and the tip of the swing arm with the base attached to the input end of the rotary potentiometer is engaged with the groove to detect angular displacement of the swing arm as the worm wheel rotates. Thus, the rotation angle of the steering shaft over the entire steering angle range is obtained, and the steering angle is detected.

  However, the rudder angle detection device of Patent Document 1 is configured to detect the rotation angle of the steering shaft for 3 to 5 rotations by the limited swing of the swing arm that occurs in the formation range of the spiral groove. Therefore, there is a problem that the detection accuracy is not sufficient. In addition, there is a problem that the range of application is limited to a steering device including a worm and a worm wheel.

  In the steering angle detection device of Patent Document 2, an angular displacement sensor is attached to the connecting portion between the output end of the steering mechanism and the tie rod, and the angular displacement of the tie rod with respect to the steering mechanism is detected. Based on this determination result and the rotation angle of the steering shaft, the rotation angle of the steering shaft over the entire steering angle range is obtained based on this determination result and the rotation angle of the steering shaft, and the steering angle is detected. It is configured.

  However, in the steering angle detection device of Patent Document 2, the angular displacement of the tie rod with respect to the output end of the steering mechanism occurs in the same direction when steering left and right, and therefore the steering direction is determined only by the detection result of one angular displacement sensor. I do not understand. For this reason, using the fact that the change rate of the angular displacement of the tie rod with respect to the output end of the steering mechanism differs between the left and right according to the steering direction, angular displacement sensors are attached to the connecting portions of the left and right output ends and the tie rod, respectively. The steering angle is obtained based on the detection results of these two angular displacement sensors, and there is a problem that the device configuration becomes complicated.

  The present invention has been made in view of such circumstances, and can detect the rotation angle of the rotating shaft over the entire steering angle range with high accuracy, and can detect the steering angle of the vehicle with a simple configuration with high accuracy. An object is to provide an apparatus.

  The steering angle detection device according to the first aspect of the invention transmits the rotation of the rotating shaft according to the operation of the steering member to the steering mechanism, and transmits the operation of the steering mechanism to the steering wheels connected via the tie rods. In the steering angle detection device for detecting the steering angle of the vehicle steered by changing the direction of the wheel by obtaining the rotation angle over a plurality of rotations of the rotation shaft, the rotation angle within one rotation of the rotation shaft is determined. A rotation angle sensor to detect, an angular displacement sensor provided at a connecting portion between the tie rod and the wheel, and a relative angular displacement of the tie rod with respect to the wheel, and a detection result of the angular displacement sensor and the rotation angle sensor And calculating means for calculating the steering angle based on the above.

  A steering angle detection device according to a second aspect of the present invention is the steering angle detection device according to the first aspect, wherein the angular displacement sensor is attached to a magnet fixed to a wheel side member of the connecting portion and a tie rod side member of the connecting portion facing the magnet. And a magnetic detection means for detecting a change in the magnetic field in accordance with the angular displacement of the magnet.

  According to the first aspect of the present invention, the relative angular displacement of the tie rod with respect to the wheel is detected by the angular displacement sensor provided at the connecting portion between the tie rod and the wheel, and a rough region in the entire steering angle range is detected based on the detection result of the angular displacement sensor. Specifically, it is determined how many rotations the rotation axis is on the left and right from the neutral position, while the rotation angle within one rotation of the rotation shaft is detected by the rotation angle sensor, and the rotation angle sensor detects The rotation angle within the region determined by the result is obtained with high accuracy, and the steering angle within the entire steering angle range is calculated. The rotation angle sensor that detects the rotation angle within one rotation can detect the rotation with high accuracy with a simple configuration, and the angular displacement sensor that is used to determine how many rotation regions the rotation axis has has high detection accuracy. Therefore, it is possible to detect the steering angle with high accuracy over the entire steering angle range with a simple configuration. Also, the relative angular displacement of the tie rod with respect to the wheel occurs in the opposite direction when steering left and right, so that the steering direction can be distinguished from the detection result of one angular displacement sensor. What is necessary is just to provide in either one of right and left.

  According to the second aspect of the invention, the angular displacement sensor detects the angular displacement of the magnet fixed to the wheel side member of the connecting portion by the magnetic detection means attached to the tie rod side member of the connecting portion so as to face the magnet. In addition, since the relative angular displacement of the tie rod with respect to the wheel can be detected in a non-contact manner, it can withstand long-term use.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram illustrating a configuration of an electric power steering apparatus including a steering angle detection apparatus according to the present invention.

  The illustrated electric power steering apparatus includes a rack and pinion type steering mechanism 1. A rack and pinion type steering mechanism 1 includes a rack shaft 10 that is supported in an axially movable manner in a rack housing 11 that extends in the left-right direction of a vehicle body (not shown), and crosses the rack housing 11 in the middle. And a pinion shaft 2 rotatably supported inside the pinion housing 20.

  Both ends of the rack shaft 10 projecting outward from both sides of the rack housing 11 are connected to knuckle arms 13 and 13 of the left and right front wheels 14 and 14 as steering wheels via separate tie rods 12 and 12, respectively, and the pinion housing An upper end of the pinion shaft 2 projecting outward from one side of the motor 20 is connected to a steering wheel 30 as a steering member via a steering shaft 3. A pinion (not shown) is formed in the middle of the pinion shaft 2 extending into the pinion housing 20, and the pinion is formed on the outer surface of the rack shaft 10 at an appropriate length at the intersection with the rack housing 11. Meshed with the rack teeth.

  The steering shaft 3 is rotatably supported inside a cylindrical column housing 31, and is attached to the interior of a vehicle compartment (not shown) while maintaining a tilted posture with the front facing down via the column housing 31. The pinion shaft 2 is connected to the projecting end of the steering shaft 3 below the column housing 31, and the steering wheel 30 is fixed to the projecting end.

  With the above configuration, when the steering wheel 30 is rotated for steering, this rotation is transmitted to the pinion shaft 2 via the steering shaft 3, and the rotation of the pinion shaft 2 is engaged with the pinion and the rack teeth. Therefore, the knuckle arms 13 of the left and right front wheels 14 and 14 are moved through the separate tie rods 12 and 12 by the movement of the rack shaft 10. It is pushed and pulled to steer.

  In the middle of the column housing 31 that supports the steering shaft 3, a torque sensor 4 that detects a steering torque applied to the steering shaft 3 by a rotation operation of the steering wheel 30 is provided, and a steering assist is provided below the torque sensor 4. A motor 5 is attached.

  As the torque sensor 4, a known twin resolver including two resolvers having different shaft angle multipliers (1/2 of the number of poles) can be used. The twin resolver is constructed by dividing the steering shaft 3 into two upper and lower shafts connected by a torsion bar, and a resolver is attached to each of the two shafts, and the rotation angle of the two shafts is detected by these two resolvers. Then, the relative angular displacement generated between the two axes in accordance with the torsion of the torsion bar is calculated, and the steering torque is calculated. The detection signals from these two resolvers are obtained as signals in which the same number of waveforms as the shaft angle multiplier appear in one rotation, and by combining these two signals, the above-mentioned relative angular displacement is obtained, and the steering shaft A rotation angle within one rotation of 3 is obtained.

  The steering assisting motor 5 is attached to the outside of the column housing 31 with its axis substantially orthogonal, and, for example, a worm fixed to an output end extending inside the column housing 31 is externally fixed to the steering shaft 3. The rotation of the motor 5 is transmitted to the steering shaft 3 after being decelerated by the worm and the worm wheel.

  Such an electric power steering device detects the steering torque applied to the steering wheel 30 by the torque sensor 4, and uses the steering shaft 3 for the rotational force of the steering assist motor 5 that is driven and controlled based on the detected torque. Therefore, it is transmitted to the pinion shaft 2 to assist the steering performed as described above.

  The steering angle detection device according to the present invention is provided at a rotation angle sensor that detects the rotation angle of the steering shaft 3 and a connection portion between the tie rod 12 and the front wheel 14, more specifically, a connection portion between the tie rod 12 and the knuckle arm 13. And an angular displacement sensor 6.

  The rotation angle sensor is a sensor that can detect the rotation angle of the steering shaft 3 within a range of one rotation. As described above, when a twin resolver is adopted as the torque sensor 4, the rotation angle within one rotation of the steering shaft 3 can be obtained from the output signal of the torque sensor 4. In this embodiment, the torque sensor 4 is It can also serve as a sensor.

  FIG. 2 is a cross-sectional view schematically showing the vicinity of the portion where the angular displacement sensor 6 is disposed. FIG. 3 is a schematic view of the surrounding area of the angular displacement sensor 6 as viewed from above. (A) shows a steering state in the left direction, (B) shows a straight traveling state, and (C) shows a right direction. The steering state of each is shown.

  As shown in FIG. 2, the tie rod 12 and the knuckle arm 13 are connected to each other by a ball joint 7 that is a connecting portion so as to be capable of relative angular displacement. The ball joint 7 includes a cylindrical ball stud (wheel side member) 70 having a spherical head at one end, and a socket (tie rod side member) 71 that makes spherical contact with the spherical head of the ball stud 70 via a resin holding member 72. And. The socket 71 is provided integrally with the tie rod 12, and the knuckle arm 13 is fixed to a cylindrical portion of a ball stud 70 protruding below the socket 71 so as to be integrally rotatable. A magnet 60 having a shape obtained by vertically dividing a short cylinder is provided on the upper part of the spherical head of the ball stud 70, and a magnetic detection means 61 is attached to the upper surface of the socket 71 so as to face the magnet 60. It is.

  An angular displacement sensor 6 including a magnet 60 and magnetic detection means 61 is a sensor that detects the angular displacement of an object to be detected using a magnetoresistive effect that resistance increases when a magnetic field is applied to a semiconductor. FIG. 4 is an equivalent circuit diagram of the angular displacement sensor 6. The magnetic detection means 61 includes two magnetoresistive elements 62 and 63, and a constant voltage is applied to both ends (between the terminals 1 and 3 in the figure). A voltage between the intermediate points of the magnetoresistive elements 62 and 63 (between terminals 1 and 2 in the figure) is detected. A magnet 60 is used as means for applying a magnetic field to the magnetic detection means 61, and the magnet 60 is angularly displaced relative to the magnetic detection means 61 as indicated by an arrow in the figure.

  FIG. 5 is a relationship diagram between the angular displacement of the magnet 60 and the output value of the angular displacement sensor 6. The horizontal axis in FIG. 5 represents the angular displacement of the magnet 60, and the vertical axis represents the output value between the terminal 1 and the terminal 2 of the angular displacement sensor 6. As shown in FIG. 5, the output value of the angular displacement sensor 6 increases or decreases substantially linearly as the area where the magnetoresistive element 62 and the magnet 60 overlap is increased or decreased.

  The magnet 60 is fixed to the spherical head of the ball stud 70 so as to be aligned with the center of the two magnetoresistive elements 62 and 63 in a straight traveling state as shown in FIG. The state of angular displacement 0 °). In such a configuration, when the knuckle arm 13 is angularly displaced to the left, the magnet 60 is also angularly displaced to the left along with the angular displacement of the knuckle arm 13 as shown in FIG. On the other hand, the magnet 60 undergoes a relative angular displacement (a state in which the angular displacement of the magnet is in the vicinity of −45 ° in FIG. 5). Due to this relative angular displacement, the magnet 60 is angularly displaced in the direction away from the magnetoresistive element 62, so that the resistance of the magnetoresistive element 62 decreases and the output value of the angular displacement sensor 6 decreases. Conversely, when the knuckle arm 13 is angularly displaced to the right, the magnet 60 is also angularly displaced to the right along with the angular displacement of the knuckle arm 13 as shown in FIG. Will be displaced relative to each other (in FIG. 5, the state in the vicinity of the angular displacement of the magnet + 45 °). Due to this relative angular displacement, the magnet 60 is angularly displaced in a direction approaching the magnetoresistive element 62, so that the resistance of the magnetoresistive element 62 increases and the output value of the angular displacement sensor 6 increases. The amount of angular displacement of the knuckle arm 13 is substantially proportional to the rotation angle of the steering shaft 3.

  The detection result by the angular displacement sensor 6 is given to the calculation unit 8 as shown in FIG. The calculation unit 8 is also given a detection result by the torque sensor 4 which also serves as a rotation angle sensor, and the calculation unit 8 determines the steering shaft over the entire steering angle range based on these detection results, as will be described later. 3 is obtained, and the steering angle of the vehicle is calculated.

  In the electric power steering apparatus provided with such a steering angle detection device, the steering shaft 3 rotates in the same direction in accordance with the rotation operation of the steering wheel 30 in the right direction or the left direction. Converted into movement in the axial direction, the left and right front wheels 14 and 14 are steered in the same direction as the operation direction of the steering wheel 30 as described above. At this time, the rotation angle sensor increases or decreases in proportion to the rotation angle of the steering shaft 3, and outputs a signal having a waveform that becomes 0 for each rotation. At the same time, the magnet 60 provided on the ball joint 7 is angularly displaced in the same direction as the rotation direction of the knuckle arm 13 and the front wheel 14. As described above, since the resistance of the magnetoresistive element 62 changes according to the angular displacement of the magnet 60, the angular displacement sensor 6 outputs a signal that increases or decreases according to the rotation angle of the steering shaft 3.

FIG. 6 is a relationship diagram between the rotation angle of the steering shaft 3 and the output values of the rotation angle sensor and the angular displacement sensor 6 during such steering. In FIG. 6A, the horizontal axis indicates the rotation angle of the steering shaft 3, the vertical axis indicates the output value of the rotation angle sensor, and the minimum value on the horizontal axis indicates the steering corresponding to the maximum steering angle on the left side of the vehicle. The maximum rotation angle on the left side of the shaft 3 is −720 °, and the maximum value on the horizontal axis indicates the maximum rotation angle on the right side of the steering shaft 3 corresponding to the maximum steering angle on the right side of the vehicle. . The maximum value and the minimum value on the horizontal axis are not limited to ± 720 °, and may be values corresponding to the maximum steering angle of the vehicle, for example, ± 780 ° or ± 900 °. Good. As shown in FIG. 6 (a), the rotation angle sensor outputs a signal in which four waveforms that become 0 every rotation (360 °) within the entire steering angle range appear. FIG. 6A shows a sawtooth signal, but this signal waveform is obtained by calculating the original signal waveform of the sensor and is not limited to the sawtooth shape. The original signal waveform of the sensor differs depending on the type of sensor, and is, for example, a sin curve or a monotone gradient waveform. As shown in FIG. 6A, for example, when V ₁ is given as the output value of the rotation angle sensor, there are _four rotation angles of the steering shaft 3 of θ ₁ , θ ₂ , θ ₃ , and θ _4. .

The horizontal axis in FIG. 6B indicates the rotation angle of the steering shaft 3 as in FIG. 6A, and the vertical axis indicates the output value of the angular displacement sensor 6. As shown in FIG. 6B, the output of the angular displacement sensor 6 indicating the relative angular displacement of the tie rod 12 with respect to the front wheels 14 is a signal that increases and decreases proportionally over the entire steering angle range. For example, when V ₂ is given as the output value of the angular displacement sensor 6, the rotation angle of the steering shaft 3 becomes one point in the entire steering angle range as shown in the figure. When the rotation angle of the steering shaft 3 over the entire steering angle range is divided into four regions corresponding to the first and second rotations on the left and right with the steering angle midpoint as the reference position, the obtained steering shaft 3 is obtained. It can be seen that the rotation angle is in the region of the first rotation in the right direction as shown in the figure.

Using this result and the rotation angle of the steering shaft 3 by the rotation angle sensor, the rotation angle of the steering shaft 3 becomes one of θ ₃ , and the rotation angle of the steering shaft 3 over the entire steering angle range is detected with high accuracy. can do. As a result, the steering angle of the vehicle can be obtained from the data of the correspondence relationship between the rotation angle of the steering shaft 3 and the steering angle over the entire steering angle range stored in the calculation unit 8 in advance. The neutral position of the steering shaft 3 is set to coincide with the steering angle midpoint.

  When the output value of the angular displacement sensor 6 is in the vicinity of the boundary of each region, by using the output value of the rotation angle sensor and the output value of the angular displacement sensor 6 at the region determination stage, how many times the steering shaft 3 rotates. It is possible to accurately determine whether it is in the eye area. Of course, at the stage of determining the region, it is possible to always determine the rotation region of the steering shaft 3 by using the output value of the rotation angle sensor and the output value of the angular displacement sensor 6.

  As described above, in the rudder angle detection device according to the present invention, the relative angular displacement of the tie rod 12 with respect to the front wheel 14 is detected by the angular displacement sensor 6 provided in the ball joint 7 that connects the tie rod 12 and the knuckle arm 13, Based on the detection result of the angular displacement sensor 6, a rough region in the entire steering angle range, specifically, the region of the left and right rotations of the steering shaft 3 from the neutral position is determined. The rotation angle within one rotation is detected by the rotation angle sensor, and the rotation angle within the region determined by the detection result of the rotation angle sensor is obtained with high accuracy to calculate the steering angle within the entire steering angle range. The rotation angle sensor that detects the rotation angle within one rotation can detect the rotation with high accuracy with a simple configuration, and the angular displacement sensor 6 used for determining the rotation region of the steering shaft 3 is high. Since detection accuracy is not required, it is possible to detect the steering angle with high accuracy over the entire steering angle range with a simple configuration. Further, since the relative angular displacement of the tie rod 12 with respect to the front wheel 14 occurs in the opposite direction when steering left and right, the steering direction can be distinguished from the detection result of one angular displacement sensor 6, and the angular displacement sensor 6 is connected to the tie rod 12 and the knuckle. What is necessary is just to provide in either one of the right and left of the ball joint 7 which connects the arm 13. FIG.

  The angular displacement sensor 6 detects the angular displacement of the magnet 60 by the magnetic detection means 61 and can detect the relative angular displacement of the tie rod 12 with respect to the front wheel 14 in a non-contact manner, so that it can withstand long-term use. Can do. Since the upper portion of the ball stud 70 of the ball joint 7 connecting the tie rod 12 and the knuckle arm 13 can be covered as usual, the socket 71 integrally provided on the tie rod 12 and the spherical head of the ball stud 70 are provided. It is difficult for foreign matters such as water, mud, and dust to enter the sliding portion, and the steering operation is not adversely affected.

  In the above embodiment, the magnetic detection means 61 is a magnetic sensor using a magnetoresistive element, but may be other types of magnetic sensors.

  Furthermore, in the present embodiment, the torque sensor 4 also serves as a rotation angle sensor, but a rotation angle sensor may be provided separately from the torque sensor 4. Needless to say, the torque sensor 4 is not limited to the twin resolver.

  In the above-described embodiment, the application example to the column assist type electric power steering apparatus in which the motor 5 is attached to the outside of the column housing 31 and the transmission shaft 3 is configured to transmit power has been described. The angle detection device can also be applied to a rack-assist type electric power steering device in which a motor is mounted on the rack housing 11 and is configured to transmit power to the rack shaft 10. The steering angle detection device according to the present invention is not limited to application to such a rack and pinion type electric power steering device, and can also be applied to other types of electric power steering devices. Further, the steering angle detection device according to the present invention is a steer-by-wire steering device and a steering mechanism that perform steering by driving a steering motor attached to a steering mechanism mechanically separated from the steering wheel. The present invention can also be applied to a hydraulic power steering device that assists steering by the generated force of an attached hydraulic cylinder, and a manual steering device that performs steering only by a steering torque applied to a steering wheel by a driver.

It is a mimetic diagram showing composition of an electric power steering device provided with a rudder angle detection device concerning the present invention. It is sectional drawing which shows schematically the arrangement | positioning site | part vicinity of an angular displacement sensor. It is the schematic which looked at the arrangement | positioning site | part of an angular displacement sensor from the top. It is an equivalent circuit diagram of an angular displacement sensor. It is a related figure of the angular displacement of a magnet and the output value of an angular displacement sensor. FIG. 6 is a relationship diagram between a rotation angle of a steering shaft and output values of a rotation angle sensor and an angular displacement sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering mechanism, 3 Steering shaft (rotating shaft), 4 Torque sensor (rotating angle sensor), 6 angular displacement sensor, 60 magnet, 61 Magnetic detection means, 7 Ball joint (connection part), 70 Ball stud (wheel side member) ), 71 socket (tie rod side member), 8 calculation unit (calculation means), 12 tie rod, 13 knuckle arm, 14 front wheel (wheel), 30 steering wheel (steering member)

Claims (2)

  The rotation of the rotating shaft according to the operation of the steering member is transmitted to the steering mechanism, the operation of the steering mechanism is transmitted to the steering wheel connected via the tie rod, and the steering wheel is steered by changing the direction of the wheel. In a rudder angle detection device that detects a steering angle of a vehicle by obtaining a rotation angle over a plurality of rotations of the rotation shaft, a rotation angle sensor that detects a rotation angle within one rotation of the rotation shaft, the tie rod, An angular displacement sensor that is provided at a connecting portion with a wheel and detects a relative angular displacement of the tie rod with respect to the wheel, and a calculation unit that calculates the steering angle based on detection results of the angular displacement sensor and the rotation angle sensor A rudder angle detection device comprising:   The angular displacement sensor is attached to a magnet fixed to a wheel side member of the connecting portion and a tie rod side member of the connecting portion so as to face the magnet, and changes a magnetic field according to the angular displacement of the magnet. The rudder angle detection device according to claim 1, further comprising a magnetic detection means for detecting.

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