JP2007263693A - 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 the vehicle steered by transmitting rotation of the steering shaft 3 according to an operation of a steering wheel 30 to wheels 12, 12 for steering to change directions of the wheels 12, 12, a moving position of a moving body 6 engaged with the steering shaft 3 and moving according to the rotation of the steering shaft 3 is detected by a position sensor 7 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 according to the detection result. The rotational angle of the steering shaft 3 in a region determined by a rotational angle sensor is acquired 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, which is a 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).
JP 2005-114676 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.

  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 present invention transmits the rotation of the rotating shaft according to the operation of the steering member to the steering wheel, and changes the direction of the wheel to determine the steering angle of the vehicle steered. In a rudder angle detection device that detects a rotation angle over a plurality of rotations, the rotation angle sensor detects a rotation angle within one rotation of the rotation shaft, and engages with the rotation shaft to rotate the rotation shaft. A moving body that moves according to the position, a position sensor that detects a moving position of the moving body, a moving position of the moving body detected by the position sensor, and a rotation angle of the rotating shaft detected by the rotation angle sensor. And a calculation means for calculating the steering angle based on the calculation result.

  In the rudder angle detection device according to a second aspect of the invention, in the first aspect of the invention, the moving body is engaged with a spiral groove carved on the outer peripheral surface of the rotating shaft, and in the axial direction according to the rotation of the rotating shaft. It is configured to move.

  A steering angle detection device according to a third invention is characterized in that, in the first invention or the second invention, the position sensor is a non-contact sensor that detects the movement of the moving body.

  According to the first aspect of the present invention, the position of the moving body that is engaged with the rotating shaft that rotates a plurality of times according to the operation of the steering member and moves according to the rotation of the rotating shaft is detected by the position sensor. Based on the detection result, a rough region in the entire steering angle range, specifically, the region of the left and right rotations from the neutral position is determined, and the rotation angle within one rotation of the rotation shaft is rotated. The steering angle is detected by the angle sensor, and the rotation angle in 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 position sensor used for determining the rotation number of the rotation axis has a high detection accuracy. Since it is not required, it is possible to detect the steering angle with high accuracy over the entire steering angle range with a simple configuration.

  According to the second invention, the movable body movable in the axial direction is engaged with the spiral groove formed on the outer peripheral surface of the rotating shaft, and the rotation of the rotating shaft is directly transmitted to the moving body. The movement of the moving body occurs surely, and it is possible to accurately determine the number of rotations in which the rotation axis is located.

  According to the third aspect of the invention, the non-contact type sensor is used to detect the moving position of the moving body, and the moving position can be detected without contacting the moving body, so that 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. The rack and pinion type steering mechanism crosses the rack housing 10 in the middle of the rack housing 10, which is supported in an axially movable manner in a rack housing 10 that extends in the left-right direction of a vehicle body (not shown). The pinion housing 20 has a known configuration including a pinion shaft 2 rotatably supported inside the pinion housing 20.

  Both ends of the rack shaft 1 projecting outward from both sides of the rack housing 10 are connected to left and right front wheels 12 and 12 as steering wheels via separate tie rods 11 and 11, and from one side of the pinion housing 20 to the outside. The upper end of the pinion shaft 2 protruding in the direction is connected to a steering wheel 30 as a steering member via the steering shaft 3. A pinion (not shown) is formed in the middle of the pinion shaft 2 extending inside the pinion housing 20, and the pinion is formed on the outer surface of the rack shaft 1 at an appropriate length at the intersection with the rack housing 10. 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. In this part, the rack shaft 1 is converted into movement in the axial length direction, and by such movement of the rack shaft 1, the left and right front wheels 12, 12 are pushed and pulled through the respective tie rods 11, 11 to steer. Is made.

  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.

  The torque sensor 4 is a known twin resolver including two resolvers having different shaft angle multipliers (1/2 of the number of poles). The steering shaft 3 is divided into two upper and lower shafts, and the two shafts are coaxially connected by a torsion bar. A resolver is attached to each of the two shafts. The torque sensor 4 detects the rotation angles of the two axes by these two resolvers, calculates the relative angular displacement generated between the two axes according to the torsion of the torsion bar, and calculates the steering torque. ing. 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.

  The electric power steering apparatus including such a steering assist motor 5 detects the steering torque applied to the steering wheel 30 by the torque sensor 4 and controls the steering assist motor 5 that is driven and controlled based on the detected torque. The rotational force is transmitted to the pinion shaft 2 via the steering shaft 3 to assist the steering performed as described above.

  The steering angle detection device according to the present invention provided in the electric power steering device as described above moves in the axial direction in accordance with the rotation angle sensor that detects the rotation angle of the steering shaft 3 and the rotation of the steering shaft 3. A moving body 6 and a position sensor 7 for detecting the position of the moving body 6 are provided.

  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.

  The moving body 6 and the position sensor 7 are provided above the torque sensor 4. FIG. 2 is a cross-sectional view schematically showing the vicinity of the site where the moving body 6 and the position sensor 7 are disposed. As shown in FIG. 2, spiral grooves 3 a having a semicircular groove shape are engraved on the outer peripheral surface of the steering shaft 3 with a constant pitch. In the column housing 31 surrounding the steering shaft 3, a guide groove 31a extending in the axial length direction is formed at one place in the circumferential direction over substantially the entire length of the formation area of the spiral groove 3a.

  A movable body 6 having a substantially rectangular parallelepiped is fitted in the guide groove 31a so as to be movable only in the axial direction. The moving body 6 includes two convex portions formed at an interval equal to the pitch of the spiral groove 3a on the opposite side of the fitting portion, and both convex portions are engaged with the spiral groove 3a.

  In such a configuration, when the steering shaft 3 rotates, the moving body 6 is moved along the guide groove 31a by the acting force on the convex portion engaged with the spiral groove 3a, as indicated by white arrows in FIG. It moves up and down only in the axial direction.

  The position sensor 7 is a sensor that can detect the movement of the moving body 6, and is attached to the column housing 31 so as to face the guide groove 31 a that is a moving path of the moving body 6. The position sensor 7 includes, for example, a known Hall IC including a Hall element using a Hall effect that a voltage is generated in a direction orthogonal to the direction of the magnetic field and the current when the direction of the current is bent by the magnetic field, and a magnetic field is applied to the semiconductor. When applied, the current distribution in the semiconductor is bent by the Lorentz force, the current path is lengthened, and a known magnetoresistive element utilizing the magnetoresistive effect of increasing the resistance is used, and the moving body 6 is provided with a magnet. May be.

  The detection result by the position sensor 7 is given to the calculation unit 8 as shown in FIG. The calculation unit 8 is also given a detection result by the rotation angle sensor described above, and the calculation unit 8 calculates the rotation angle of the steering shaft 3 over the entire steering angle range based on these detection results, as will be described later. Obtain the steering angle of the vehicle.

  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. It is converted into movement in the axial direction, and the left and right front wheels 12 and 12 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 moving body 6 engaged with the steering shaft 3 moves upward or downward along the guide groove 31a. Since the positional relationship between the moving body 6 and the position sensor 7 changes according to this movement, the position sensor 7 outputs a signal that increases or decreases according to the rotation angle of the steering shaft 3.

FIG. 3 is a relationship diagram between the rotation angle of the steering shaft 3 and the output values of the rotation angle sensor and the position sensor 7 during such steering. In FIG. 3A, 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 to Fig.3 (a), a rotation angle sensor outputs the signal which four waveforms which become 0 for every 1 rotation (360 degrees) within the whole steering angle range appear. FIG. 3A 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. For example, when V ₁ is given as the output value of the rotation angle sensor, as shown in FIG. 3A, 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. 3B indicates the rotation angle of the steering shaft 3 as in FIG. 3A, and the vertical axis indicates the output value of the position sensor 7. The output of the position sensor 7 indicating the moving position of the moving body 6 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 position sensor 7, 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. When the determination result using the rotation angle of the steering shaft 3 by the rotation angle sensor, the rotation angle of the steering shaft 3 becomes a 1 Street theta _3, to determine the rotation angle of the steering shaft 3 over the entire steering angle range 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 position sensor 7 is near the boundary of each region, the rotation number of the steering shaft 3 is determined by using the output value of the rotation angle sensor and the output value of the position sensor 7 at the region determination stage. It is possible to accurately determine whether it is in the area. Of course, 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 position sensor 7 in the region determination stage.

  As described above, in the steering angle detection device according to the present invention, the moving position of the moving body 6 that is engaged with the steering shaft 3 that rotates a plurality of times according to the operation of the steering wheel 30 and moves according to the rotation of the steering shaft 3. Is detected by the position sensor 7, and a rough region in the entire steering angle range is determined based on the detection result of the position sensor 7, specifically, the rotation region on the left and right of the steering shaft 3 is determined from the neutral position On the other hand, the rotation angle within one rotation of the steering shaft 3 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 within the entire steering angle range. Calculate the rudder angle. 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 position sensor 7 used for determining how many rotations the steering shaft 3 is in has a high detection. Since 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.

  Since the movable body 6 movable in the axial length direction is engaged with the spiral groove 3a engraved on the outer peripheral surface of the steering shaft 3, the rotation of the steering shaft 3 is directly transmitted to the movable body 6. The movement of the moving body 6 occurs surely, and it is possible to accurately determine how many rotations the steering shaft 3 is in.

  Further, a non-contact type sensor such as a magnetic sensor is used to detect the moving position of the moving body 6, and the moving position can be detected without contacting the moving body 6, so that it can withstand long-term use. .

  In the above embodiment, the moving body 6 is provided at a position above the torque sensor 4. However, the moving body 6 is disposed at an appropriate portion of the rotating shaft that rotates a plurality of times according to the operation of the steering wheel 30. be able to. For example, the steering shaft 3 may be extended downward, and the moving body 6 may be provided in the extending portion, or the moving body 6 may be provided in the extending portion that extends the pinion shaft 2 or the pinion shaft 2 downward. Good.

  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.

  Further, for detection of the moving body 6, in addition to the present embodiment, an excitation coil type or MR type sensor may be used as a magnetic type. In addition to the magnetic type, non-contact such as an optical type and a capacitance type may be used. A type-type position sensor can be used.

  Further, in the 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 is configured to transmit to the steering shaft 3 has been described, but the steering angle detection according to the present invention is described. The apparatus can also be applied to a rack-assist type electric power steering apparatus in which a motor is attached to the rack housing 10 and the power is transmitted to the rack shaft 1. Furthermore, the steering angle detection device according to the present invention is applicable to a steer-by-wire type steering device that performs steering by driving a motor attached to a steering mechanism mechanically separated from the steering wheel 30. In addition, the present invention can also be applied to a manual steering device that performs steering only by a steering torque applied to the steering wheel 30 by the 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 a moving body and a position sensor. FIG. 6 is a relationship diagram between a rotation angle of a steering shaft and output values of a rotation angle sensor and a position sensor.

Explanation of symbols

3 steering shaft (rotating shaft), 3a spiral groove, 4 torque sensor (rotation angle sensor), 6 moving body, 7 position sensor, 8 calculating unit (calculating means), 12 wheels, 30 steering wheel (steering member)

Claims (3)

  The rotation of the rotating shaft corresponding to the operation of the steering member is transmitted to the steering wheel, and the steering angle of the vehicle steered by changing the direction of the wheel is detected by obtaining the rotation angle over a plurality of rotations of the rotating shaft. In the rudder angle detection device, a rotation angle sensor that detects a rotation angle within one rotation of the rotation shaft, a moving body that engages with the rotation shaft and moves according to the rotation of the rotation shaft, and the moving body A position sensor for detecting the moving position of the moving body, and a calculating means for calculating the steering angle based on the moving position of the moving body detected by the position sensor and the rotation angle of the rotating shaft detected by the rotation angle sensor; A rudder angle detection device comprising:   The rudder angle according to claim 1, wherein the movable body is engaged with a spiral groove formed on an outer peripheral surface of the rotating shaft, and is configured to move in an axial length direction according to the rotation of the rotating shaft. Detection device.   The rudder angle detection device according to claim 1, wherein the position sensor is a non-contact type sensor that detects movement of the moving body.

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