JP4900167B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus.

  Conventionally, in a steering apparatus for a vehicle, a steering angle ratio variable device (hereinafter referred to as a steering angle ratio) that varies a transmission ratio between a steering angle of a steering wheel and a steering angle of a steered wheel (hereinafter referred to as a steering angle ratio) by an output of an electric motor. And an electric power steering device (hereinafter abbreviated as EPS) that assists the turning of the steered wheels by the output of the electric motor.

  For example, the vehicle steering device of Patent Document 1 includes a rack and pinion type steering gear mechanism, and a main part of a VGRS including an electric motor is incorporated on a force transmission path from a steered wheel to a pinion so that the vehicle can be rotated from the rack. An EPS electric motor is incorporated on a force transmission path to the steering wheel (hereinafter, the VGRS electric motor is referred to as a first electric motor, and the EPS electric motor is referred to as a second electric motor). However, according to the vehicle steering apparatus of Patent Document 1, since the second electric motor is incorporated on the force transmission path from the rack to the steered wheels, there is a high possibility that water droplets or the like adhere to the second electric motor. It lacks protection against the outside.

  On the other hand, according to the vehicle steering device of Patent Document 2, the main part of the VGRS including the first electric motor and the main part of the EPS including the second electric motor on the force transmission path from the steering wheel to the pinion. Both of these are incorporated, and the problem caused by incorporating the second electric motor on the force transmission path from the rack to the steered wheels is solved. However, when both the first and second electric motors are incorporated on the force transmission path from the steering wheel to the pinion, it is necessary to arrange the first and second electric motors in a vehicle having a large number of devices. 1. There are significant restrictions on the incorporation of the second electric motor.

  That is, when both the first and second electric motors are incorporated in the transmission path of the force from the steering wheel to the pinion and arranged in the vehicle, the mountability of the vehicle steering device is lowered.

  In addition, the conventional vehicle steering apparatus includes a second electric motor and a control apparatus that controls the operation of the second electric motor in order to prevent the EPS from malfunctioning and causing troubles in turning the steered wheels. Are parallelized (for example, refer to Patent Document 3), or the drive circuit mounted on the control device is parallelized (for example, refer to Patent Document 4).

As described above, according to the conventional vehicle steering apparatus, the provision of the spare such as the second electric motor can cope with the failure of the EPS. For this reason, the conventional vehicle steering apparatus has been regarded as problematic in terms of cost increase and size increase due to the provision of a spare for dealing with EPS failures.
JP-A-5-105103 JP 2003-72574 A JP 2003-200840 A JP 2004-80939 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicular steering apparatus including a VGRS and an EPS, both of the first electric motor of the VGRS and the second electric motor of the EPS. Even if it is installed on the power transmission path from the steering wheel to the pinion and placed in the vehicle, it does not reduce the mountability, and eliminates the increase in cost and the increase in size due to the provision of a spare for EPS failure. .

[Means of Claim 1]
The vehicle steering apparatus according to claim 1 is a steering angle ratio variable device (VGRS) that varies a transmission ratio (steering angle ratio) between a steering angle of a steered wheel and a steered wheel by an output of a first electric motor. And an electric power steering device (EPS) that assists the turning of the steered wheels by the output of a second electric motor different from the first electric motor.

The VGRS is provided integrally with the steered wheel, is rotated by a steering force applied to the steered wheel, is rotatably incorporated with respect to the steering shaft, and is driven to rotate by the output of the first electric motor. A first rotating member that is mechanically connected to the steered wheel and can transmit the output of the first electric motor to the steered wheel; a rotation angle detecting unit that detects a relative rotation angle between the steering shaft and the first rotating member; And a first control means for controlling the operation of the first electric motor in accordance with the rotation angle. The mechanical connection between the first rotating member and the steered wheel allows the steered wheel also by the output of the first electric motor. Can be used to assist the steering .

Further, the EPS is rotationally driven by the output of the second electric motor and mechanically connected to the first rotating member and the steered wheel, and transmits the output of the second electric motor to the steered wheel; Torque detecting means for detecting torque transmitted from the first rotating member to the second rotating member, and second control means for controlling the operation of the second electric motor in accordance with the torque.
The first electric motor and the second electric motor have substantially the same shape and the same rating, and form one module.

  The second control means stops the control on the second electric motor when a failure occurs in the EPS, and the first control means stops the control on the second electric motor due to the failure of the EPS. Then, the operation of the first electric motor is controlled so as to assist the turning of the steered wheels by the output of the first electric motor.

  First, by making the first and second electric motors into one module, the first and second electric motors can be arranged close to each other. Therefore, the first and second electric motors are separated from each other and arranged in the vehicle. In addition, the mountability of the vehicle steering device can be improved.

  In addition, according to the conventional vehicle steering apparatus, the second electric motor requires a large output to assist the steering of the steered wheels, and a large model is adopted. The first electric motor has a steering angle ratio. Small enough to be maintained. Such unbalance in the size of the first and second electric motors has also been a factor in reducing the mountability of the vehicle steering system.

  In contrast, according to the first aspect of the present invention, since the first rotating member that is rotationally driven by the output of the first electric motor is mechanically connected to the steered wheels, the rolling is also performed by the output of the first electric motor. It is possible to assist the steering of the steering wheel. Therefore, the first electric motor is made larger than before, and the second electric motor is made smaller than before, thereby eliminating the unbalance in the size of the first and second electric motors without lowering the assist capability. can do. Further, since the unbalance of the sizes of the first and second electric motors is eliminated, the module including the first and second electric motors has a balanced shape. Can increase the sex.

  Further, since the first rotating member is mechanically connected to the steered wheels, even if the EPS fails and the second electric motor cannot assist the steering of the steered wheels, the output of the first electric motor It becomes possible to assist the turning of the steered wheels. For this reason, it is possible to cope with an EPS failure by modifying the first and second control means as described above without providing a spare such as the second electric motor. As a result, in a vehicle steering apparatus equipped with VGRS and EPS, it is possible to eliminate an increase in cost and an increase in size due to the provision of a backup for failure of EPS.

[Means of claim 2]
According to the vehicle steering apparatus of the second aspect, the first control means stops the control on the first electric motor when the failure occurs in a portion other than the rotation angle detection means of the VGRS, and the second control The means is such that when the first control means stops control of the first electric motor due to a failure of a portion excluding the rotation angle detection means of the VGRS, the relative rotation angle falls within a predetermined range by the output of the second electric motor. The operation of the second electric motor is controlled.

  Even if VGRS fails and the first electric motor cannot change the steering angle ratio because the second rotating member is mechanically connected to the first rotating member, the steering angle is controlled by the output of the second electric motor. It becomes possible to vary the ratio. For this reason, by modifying the first and second control means as described above, it is possible to cope with a failure of the VGRS excluding the failure of the rotation angle detection means.

  The vehicle steering apparatus of the best mode is an EPS that assists the turning of steered wheels by the output of a second electric motor different from the first electric motor, and VGRS whose steering angle ratio is variable by the output of the first electric motor. With.

The VGRS is provided integrally with the steered wheel, is rotated by a steering force applied to the steered wheel, is rotatably incorporated with respect to the steering shaft, and is driven to rotate by the output of the first electric motor. A first rotating member that is mechanically connected to the steered wheel and can transmit the output of the first electric motor to the steered wheel; a rotation angle detecting unit that detects a relative rotation angle between the steering shaft and the first rotating member; And a first control means for controlling the operation of the first electric motor in accordance with the rotation angle. The mechanical connection between the first rotating member and the steered wheel allows the steered wheel also by the output of the first electric motor. Can be used to assist the steering .

Further, the EPS is rotationally driven by the output of the second electric motor and mechanically connected to the first rotating member and the steered wheel, and transmits the output of the second electric motor to the steered wheel; Torque detecting means for detecting torque transmitted from the first rotating member to the second rotating member, and second control means for controlling the operation of the second electric motor in accordance with the torque.
The first electric motor and the second electric motor have substantially the same shape and the same rating, and form one module.

  The second control means stops the control on the second electric motor when a failure occurs in the EPS, and the first control means stops the control on the second electric motor due to the failure of the EPS. Then, the operation of the first electric motor is controlled so as to assist the turning of the steered wheels by the output of the first electric motor.

  Further, the first control means stops the control on the first electric motor when a failure occurs in a portion other than the rotation angle detection means of the VGRS, and the second control means is configured such that the first control means has the rotation angle of the VGRS. When the control of the first electric motor is stopped due to a failure of a portion other than the detection means, the operation of the second electric motor is controlled so that the relative rotation angle is within a predetermined range by the output of the second electric motor.

[Configuration of Example 1]
A vehicle steering apparatus 1 according to a first embodiment will be described with reference to the drawings.
As shown in FIG. 1, the vehicle steering apparatus 1 determines the transmission ratio (steering angle ratio) between the steering angle of the steered wheel 2 and the steered angle of the steered wheel (not shown) by the output of the first electric motor 3. A variable steering angle ratio variable device (VGRS) 4 and an electric power steering device (EPS) 6 that assists the turning of the steered wheels by the output of a second electric motor 5 different from the first electric motor 3 are provided.

  Further, the vehicle steering apparatus 1 includes a rack and pinion type steering gear mechanism 9, and a main part of the VGRS 4 including the first electric motor 3 on the force transmission path from the steering wheel 2 to the pinion 10, and the first The essential part of the EPS 6 including the two electric motors 5 is incorporated.

  As shown in FIGS. 1 and 2, the VGRS 4 is provided integrally with the steering wheel 2, and is incorporated into the steering shaft 12 that is rotated by a steering force applied to the steering wheel 2, and is rotatable with respect to the steering shaft 12. A first rotating member 13 that is rotationally driven by the output of the first electric motor 3 and mechanically connected to the steered wheels and can transmit the output of the first electric motor 3 to the steered wheels, and the steering shaft 12 and the first rotation. A rotation angle detection unit 14 that detects a relative rotation angle with respect to the member 13 and a first control unit 15 that controls the operation of the first electric motor 3 according to the detected relative rotation angle.

  For example, as shown in FIG. 3, the first electric motor 3 includes three-phase coils 18 to 20 incorporated in a stator, and a magnet (not shown) incorporated in a rotor. 20 is a brushless synchronous motor that generates torque by the interaction between a current flowing through the magnetic field 20 and a magnetic field formed by a magnet.

Further, the first electric motor 3 is equipped with a position sensor 21 for detecting the rotational position of the rotor, and the energization amount to the coils 18 to 20 is detected by a current detection means 22 comprising, for example, three current detection resistors. . The detected value of the rotational position of the rotor and the detected value of the energization amount to the coils 18 to 20 are input to the first control means 15 and used for controlling the first electric motor 3.
The output shaft of the first electric motor 3 forms a worm 23 as shown in FIGS.

  As shown in FIGS. 1 and 2, the first rotating member 13 is provided in a cylindrical shape and is disposed on the outer peripheral side of the cylindrical shaft portion 26 and a cylindrical shaft portion 26 that is arranged coaxially with the steering shaft 12. It has a worm wheel 27 which is provided in a disc shape and meshes with the worm 23. As shown in FIG. 2, the cylindrical shaft portion 26 forms a nested structure together with the distal end portion of the steering shaft 12, and the distal end of the steering shaft 12 is rotated with respect to the first rotating member 13 by the ball bearing 28. It is freely supported. The worm wheel 27 serves as an input portion of the first rotating member 13 for the worm 23 that is an output portion of the first electric motor 3.

  As shown in FIG. 2, the rotation angle detection unit 14 includes a shaft side detection unit 30 that detects the rotation angle of the steering shaft 12 and a rotation member side detection unit 31 that detects the rotation angle of the first rotation member 13. .

  As shown in FIGS. 2 and 4, the shaft-side detection means 30 includes two shaft-side magnets 33 assembled on the outer peripheral surface of the steering shaft 12 and two magnetic flux densities for detecting the magnetic flux density formed by the shaft-side magnets 33. The shaft-side magnetic field detecting means 34 and 35 and the shaft-side nut-like member 36 on which the shaft-side magnetic field detecting means 34 and 35 are mounted are included.

  The shaft-side magnetic field detectors 34 and 35 have, for example, a hall element (not shown) that detects the magnetic flux density of a magnetic field and a processing circuit (not shown) that digitally processes an output signal obtained from the hall element. This is a packaged Hall IC. Further, the shaft-side magnetic field detecting means 34 and 35 are mounted on the shaft-side nut-like member 36 with an interval of 90 ° in the circumferential direction.

  The shaft-side nut-like member 36 is provided with a female screw 40 that is screwed with a male screw 39 on the outer peripheral surface of the steering shaft 12. As a result, the shaft-side nut-like member 36 is screwed into the steering shaft 12. Further, the shaft-side nut-like member 36 is provided with a flat outer peripheral edge 43 that is in surface contact with the flat inner peripheral face 42 of the annular member 41 in the radial direction, and by surface contact between the inner peripheral face 42 and the flat outer peripheral edge 43. Rotation is regulated. As a result, even if the steering shaft 12 rotates, the shaft-side nut-like member 36 moves up and down in the axial direction without rotating.

  As described above, the shaft-side magnet 33 rotates without moving up and down in the axial direction as the steering shaft 12 rotates. Further, the shaft-side magnetic field detecting means 34 and 35 move up and down in the axial direction without rotating as the shaft-side nut-like member 36 moves up and down.

  Therefore, the detection signals output from each of the shaft-side magnetic field detecting means 34 and 35 are sinusoidal with respect to the rotation angle of the steering shaft 12 and the shaft-side magnet 33 and the two magnets as shown in FIG. As the axial distance from the shaft-side magnetic field detection means 34, 35 increases (that is, as the absolute value of the rotation angle increases or decreases from a predetermined specific value), the amplitude of the sine wave It changes so that becomes small.

  Further, since the shaft-side magnetic field detection means 34 and 35 are mounted at an interval of 90 ° in the circumferential direction, the detection signal output from the shaft-side magnetic field detection means 34 and the shaft-side magnetic field detection means 35 are output. The detected signal is 90 ° out of phase.

  As shown in FIGS. 2 and 4, the rotating member side detection unit 31 includes a rotating member side magnet 46 assembled on the outer peripheral surface of the first rotating member 13 and a magnetic flux density of a magnetic field formed by the rotating member side magnet 46. Two rotating member side magnetic field detecting means 47 and 48, and a rotating member side nut-like member 49 on which the rotating member side magnetic field detecting means 47 and 48 are mounted.

  The rotating member side magnetic field detecting means 47 and 48 include, for example, a Hall element (not shown) for detecting the magnetic flux density of the magnetic field and a processing circuit (not shown) for digitally processing an output signal obtained from the Hall element. This is a Hall IC packaged in one package. The rotating member-side magnetic field detecting means 47 and 48 are mounted on the rotating member-side nut-like member 49 at an interval of 90 ° in the circumferential direction.

  The rotating member-side nut-like member 49 is provided with a female screw 53 that is screwed with the male screw 52 on the outer peripheral surface of the first rotating member 13. Thereby, the rotating member side nut-like member 49 is screwed into the first rotating member 13. Further, the rotating member side nut-like member 49 is provided with a flat outer peripheral edge 56 in surface contact with the flat inner peripheral surface 55 of the annular member 54 in the radial direction, and the surface contact between the inner peripheral surface 55 and the flat outer peripheral edge 56 is provided. The rotation is regulated by As a result, even if the first rotating member 13 rotates, the rotating member-side nut-like member 49 moves up and down in the axial direction without rotating.

  As described above, the rotating member side magnet 46 rotates without moving up and down in the axial direction as the first rotating member 13 rotates. The rotating member side magnetic field detecting means 47 and 48 move up and down in the axial direction without rotating as the rotating member side nut-like member 49 moves up and down.

  Therefore, the detection signals output from each of the rotating member side magnetic field detecting means 47 and 48 are also sinusoidal with respect to the rotation angle of the first rotating member 13 as shown in FIG. As the axial distance between 46 and the two rotating member-side magnetic field detecting means 47 and 48 increases (that is, as the absolute value of the rotation angle increases or decreases from a predetermined specific value). ) It changes so that the amplitude of the sine wave becomes small.

  Further, since the rotating member side magnetic field detecting means 47 and 48 are mounted at an interval of 90 ° in the circumferential direction, the detection signal output from the rotating member side magnetic field detecting means 47 and the rotating member side magnetic field detecting means 48 are mounted. Is 90 ° out of phase with the detection signal output from.

  As shown in FIG. 3, the first control unit 15 includes an input device 60 that performs input processing of detection signals from various detection units such as the current detection unit 22, the position sensor 21, the rotation angle detection unit 14, and the vehicle speed sensor 59. A CPU 61 that has a control function and an arithmetic function, calculates a command value for controlling the first electric motor 3 based on various detection values obtained from the input device 60, and is used for control processing and arithmetic processing by the CPU 61. A storage device (not shown) for storing various data and a control program to be output, and an output device 62 for synthesizing and outputting a command signal for controlling the first electric motor 3 in accordance with a command value obtained from the CPU 61 It is comprised as a known microcomputer containing.

  Further, the first control means 15 has an inverter 63 composed of six MOSFETs that operate in response to a command signal output from the output device 62, a power supply IC 64, a fuse 65, a fuse relay 66, and the like. And a known power supply circuit 68 for supplying power to the inverter 63 to constitute one electronic control unit (ECU) (hereinafter, the first control means 15 is referred to as a first ECU 15).

  As shown in FIGS. 1 and 2, the EPS 6 is rotationally driven by the output of the second electric motor 5 and mechanically connected to the first rotating member 13 and the steered wheel, and outputs the output of the second electric motor 5. The second rotating member 72 transmitted to the steered wheels, the torque detecting means 73 for detecting the torque transmitted from the first rotating member 13 to the second rotating member 72, and the second electric motor 5 according to the detected torque. Second control means 74 for controlling the operation.

  The second electric motor 5 includes, for example, as shown in FIG. 6, three-phase coils 76 to 78 incorporated in the stator and magnets (not shown) incorporated in the rotor. This is a brushless synchronous motor that generates torque by the interaction between a current flowing through 78 and a magnetic field formed by a magnet.

Further, the second electric motor 5 is equipped with a position sensor 79 for detecting the rotational position of the rotor, and the energization amount to the coils 76 to 78 is detected by a current detection means 80 comprising, for example, three current detection resistors. . The detected value of the rotational position of the rotor and the detected value of the energization amount to the coils 76 to 78 are input to the second control means 74 and used for controlling the second electric motor 5.
The output shaft of the second electric motor 5 forms a worm 81 as shown in FIGS. 1 and 2 and has substantially the same diameter as the worm 23 of the first electric motor 3. The second electric motor 5 has the same shape and the same rating as the first electric motor 3.

  As shown in FIGS. 1 and 2, the second rotating member 72 includes a cylindrical shaft portion 84 that is provided in a cylindrical shape and is arranged coaxially with the steering shaft 12 and the first rotating member 13, and a cylindrical shaft portion. A worm wheel 85 that is provided in a substantially disc shape on the outer peripheral side of 84 and meshes with the worm 81 is provided.

  As shown in FIG. 2, the cylindrical shaft portion 84 is provided integrally with the cylindrical shaft portion 26 together with a torsion bar 87 described later. That is, the first and second rotating members 13 and 72 are mechanically coupled to each other by being provided integrally with the torsion bar 87. The worm wheel 85 is an input part of the second rotating member 72 to the worm 81 that is the output part of the second electric motor 5, and has substantially the same diameter as the worm wheel 27 of the first rotating member 13.

  As shown in FIG. 2, the torque detection means 73 includes a torsion bar 87 that is provided in a substantially cylindrical shape and stores elastic force in the circumferential direction by torsion associated with a torque load, and a magnet 88 that is incorporated in the outer peripheral surface of the torsion bar 87. And magnetic field detecting means 89 for detecting the magnetic flux density of the magnetic field formed by the magnet 88.

  The torsion bar 87 is provided coaxially with the cylindrical shaft portions 26 and 84 to mechanically connect the first and second rotating members 13 and 72 to each other, and from the first rotating member 13 to the second rotating member 72. Create a torque transmission path. The magnetic field detecting means 89 includes a comb-like annular tooth 90 made of a ferromagnetic material fixed to the inner periphery of the cylindrical shaft portion 84 and a Hall IC 91.

  Thus, when the torsion bar 87 is twisted and the relative position between the magnet 88 and the annular tooth 90 changes, the magnetic flux density of the magnetic field detected by the Hall IC 91 changes. As a result, the torque detecting means 73 converts the torsion amount of the torsion bar 87 into a change in magnetic flux density and detects the change in the magnetic flux density with the magnetic field detecting means 89, whereby the first rotating member 13 to the second rotating member 72. The torque transmitted to can be detected.

  As shown in FIG. 6, the second control unit 74 includes an input device 93 that performs input processing of detection signals from various detection units such as a current detection unit 80, a position sensor 79, a torque detection unit 73, and a vehicle speed sensor 59, and the like. The CPU 94 has a control function and an arithmetic function, and calculates a command value for controlling the second electric motor 5 based on various detection values obtained from the input device 93, and is used for control processing and arithmetic processing by the CPU 94. A storage device (not shown) that stores various data and a control program, and an output device 95 that synthesizes and outputs a command signal for controlling the second electric motor 5 in accordance with a command value obtained from the CPU 94. It is comprised as a known microcomputer containing.

  Further, the second control means 74 includes an inverter 96 composed of six MOSFETs that operate in response to a command signal output from the output device 95, a power supply IC 97, a fuse 98, a fuse relay 99, and the like. And a well-known power supply circuit 100 for supplying power to the inverter 96 to constitute one electronic control unit (ECU) (hereinafter, the second control means 74 is referred to as a second ECU 74).

  In the vehicle steering apparatus 1 having the above configuration, the first and second electric motors 3 and 5, the first and second rotating members 13 and 72, the first and second ECUs 15 and 74, the rotation angle detecting means 14 and the torque detection. The means 73 forms one module 104.

  As shown in FIG. 2, the module 104 is also provided including the tip of the steering shaft 12 having the shaft-side magnet 33 and the male screw 39, and the tip of the steering shaft 12, the first and second rotating members 13, 72. The rotation angle detection means 14 and the torque detection means 73 are accommodated in one housing 106. The casing 106 is provided integrally with the annular members 41 and 54.

The first and second ECUs 15 and 74 are arranged in a column in the axial direction and housed in one housing (hereinafter referred to as an ECU housing 107: see FIG. 7). The first and second electric motors 3 and 5 are The worms 23 and 81 are assembled in a column in the ECU housing 107 so as to protrude.
And the module 104 is comprised by mounting | wearing the housing | casing 106 which accommodates the 1st, 2nd rotating members 13, 72 grade | etc., With the ECU housing 107 which assembled | attached the 1st, 2nd electric motors 3 and 5. FIG.

[Control Method of Example 1]
According to the vehicle steering apparatus 1 of the first embodiment, the first ECU 15 also receives a detection signal from the torque detection means 73 as shown in FIG. Further, as shown in FIG. 6, the second ECU 74 also receives a detection signal input from the rotation angle detection means 14. Further, the first and second ECUs 15 and 74 are provided so as to be able to input and output control signals with each other.

  Then, the second ECU 74 stops control of the second electric motor 5 when a failure occurs in the EPS 6, and the first ECU 15 stops when the second ECU 74 stops control of the second electric motor 5 due to a failure of the EPS 6. The operation of the first electric motor 3 is controlled so as to assist the turning of the steered wheels by the output of the first electric motor 3.

  Note that the failure of the EPS 6 that should execute the alternative assist control by the first electric motor 3 is a failure that causes a fatal failure in the operation of the second electric motor 5, for example, abnormal output of the torque detection means 73, CPU 94. It is conceivable that there is an abnormality in the calculation of the command value due to the above, other abnormality of the CPU 94, disconnection of the second electric motor 5, failure of the MOSFET of the inverter 96, and the like.

  Further, the first ECU 15 stops the control of the first electric motor 3 when a failure occurs in a portion other than the rotation angle detection means 14 of the VGRS 4, and the second ECU 74 causes the first ECU 15 to change the rotation angle detection means 14 of the VGRS 4. When the control of the first electric motor 3 is stopped due to a failure of the part other than that, the operation of the second electric motor 5 is controlled so that the relative rotation angle is within a predetermined range by the output of the second electric motor 5.

  Note that the failure of the VGRS 4 that should execute the alternative steering angle ratio control by the second electric motor 5 is a failure that causes a fatal failure in the operation of the first electric motor 3. Other abnormalities of the CPU 61, disconnection of the first electric motor 3, failure of the MOSFET of the inverter 63, and the like are conceivable.

  Here, the failure of the rotation angle detection unit 14 (that is, the output abnormality of the rotation angle detection unit 14) is also considered to be a failure that causes a fatal failure in the operation of the first electric motor 3. However, if the rotation angle detection unit 14 breaks down, control over the steering angle ratio becomes impossible. Therefore, for the failure of the rotation angle detection unit 14, a detection value by the rotation angle detection unit 14 is not separately used. A mechanism and control method that can control the steering angle ratio are required.

  Below, the alternative assist control by the 1st electric motor 3 and the control processing of the alternative steering angle ratio control by the 2nd electric motor 5 are demonstrated using the flowchart shown in FIGS.

First, the processing flow of the alternative assist control by the first electric motor 3 will be described with reference to FIGS.
First, as shown in FIG. 8, it is determined in step S1 whether or not any failure has occurred in the second electric motor 5. If it is determined that some failure has occurred in the second electric motor 5 (YES), the process proceeds to step S2, and if it is determined that no failure has occurred in the second electric motor 5 (NO), the process proceeds to step S3. Proceed to perform normal assist control. Each step shown in FIG. 8 is executed by the second ECU 74.

  Next, in step S <b> 2, it is determined whether an output abnormality has occurred in the torque detection means 73. If it is determined that an output abnormality has occurred in the torque detection means 73 (YES), the process proceeds to step S4, where the assist control by the second electric motor 5 is stopped, and the treatment accompanying the stop of the assist control of the second electric motor 5 is performed. Execute. That is, the relays are opened at step S5, an error code is recorded at step S6, a control signal for taking over assist control from the second ECU 74 to the first ECU 15 is output to the first ECU 15 at step S7, and the power supply 67 is output at step S8. To the second ECU 74 is turned off.

  If it is determined in step S2 that no output abnormality has occurred in the torque detection means 73 (NO), the process proceeds to step S9, and it is determined whether or not an abnormality in command value calculation by the CPU 94 has occurred.

  If it is determined in step S9 that an abnormality in the calculation of the command value by the CPU 94 has occurred (YES), the process proceeds to steps S4 to S8 to stop the assist control by the second electric motor 5, and to deal with the stop of the assist control. Execute. If it is determined that there is no abnormality in command value calculation by the CPU 94 (NO), the process proceeds to step S10, where it is determined whether other abnormality of the CPU 94 has occurred.

  If it is determined in step S10 that another abnormality of the CPU 94 has occurred (YES), the process proceeds to steps S4 to S8, where the assist control is stopped by the second electric motor 5 and the measures associated with the stop of the assist control are executed. To do. If it is determined that no other abnormality of the CPU 94 has occurred (NO), the process proceeds to step S11, and it is determined whether or not a disconnection has occurred in the second electric motor 5.

  If it is determined in step S11 that the disconnection has occurred in the second electric motor 5 (YES), the process proceeds to steps S4 to S8 to stop the assist control by the second electric motor 5, and to deal with the stop of the assist control. Execute. If it is determined that no breakage has occurred in the second electric motor 5 (NO), the process proceeds to step S12 to determine whether or not a failure has occurred in the MOSFET of the inverter 96.

  If it is determined in step S12 that a failure has occurred in the MOSFET of the inverter 96 (YES), the process proceeds to steps S4 to S8 to stop the assist control by the second electric motor 5, and to take measures associated with the stop of the assist control. Execute. If it is determined that a failure has not occurred in the MOSFET of the inverter 96 (NO), the process proceeds to step S13, and a normal fail-safe procedure is executed.

  Next, as shown in FIG. 9, in step S <b> 20, it is determined whether or not a control signal for taking over assist control from the second ECU 74 to the first ECU 15 is input to the first ECU 15. When the control signal for taking over the assist control is input to the first ECU 15 (YES), the process proceeds to step S21 and the steering angle ratio control by the first electric motor 3 is stopped. When the control signal for taking over the assist control is not input to the first ECU 15 (NO), the routine proceeds to step S22 and normal steering angle ratio control is executed. Each step shown in FIG. 9 is executed by the first ECU 15.

  Subsequently, the process proceeds from step S21 to step S23, and it is determined whether or not the steered wheel 2 is stationary. If it is determined that the steering wheel 2 is stationary (YES), the process returns to step S23. If it is determined that the steered wheel 2 is not stationary (NO), the process proceeds to step S24 to determine whether the steered wheel 2 is steered to the right.

  If it is determined in step S24 that the steered wheel 2 is steered to the right (YES), the process proceeds to step S25, the first electric motor 3 is operated to assist the steering of the steered wheel 2 to the right, and the process returns to step S23. . If it is determined that the steered wheel 2 is steered to the left (NO), the process proceeds to step S26, the first electric motor 3 is operated to assist left steering of the steered wheel 2, and the process returns to step S23.

Next, a processing flow of alternative steering angle ratio control by the second electric motor 5 will be described with reference to FIGS. 10 and 11.
First, as shown in FIG. 10, it is determined in step S31 whether or not any failure has occurred in the first electric motor 3. If it is determined that some failure has occurred in the first electric motor 3 (YES), the process proceeds to step S32. If it is determined that no failure has occurred in the first electric motor 3 (NO), the process proceeds to step S33. Go ahead and execute normal steering angle ratio control. Each step shown in FIG. 10 is executed by the first ECU 15.

  Next, in step S32, it is determined whether or not a command value calculation abnormality by the CPU 61 has occurred. If it is determined that an abnormality in the calculation of the command value by the CPU 61 has occurred (YES), the process proceeds to step S34, the steering angle ratio control by the first electric motor 3 is stopped, and the steering angle ratio control of the first electric motor 3 is stopped. Perform the actions associated with the stop. That is, the relays are opened in step S35, an error code is recorded in step S36, a control signal for taking over the steering angle ratio control from the first ECU 15 to the second ECU 74 is output to the second ECU 74 in step S37, and in step S38. Power supply from the power source 67 to the first ECU 15 is turned off.

  If it is determined in step S32 that there is no abnormality in the calculation of the command value by the CPU 61 (NO), the process proceeds to step S39, where it is determined whether any other abnormality of the CPU 61 has occurred.

  If it is determined in step S39 that other abnormality of the CPU 61 has occurred (YES), the process proceeds to steps S34 to S38 to stop the steering angle ratio control by the first electric motor 3, and stop this steering angle ratio control. Perform the associated action. If it is determined that no other abnormality of the CPU 61 has occurred (NO), the process proceeds to step S40, and it is determined whether or not a disconnection has occurred in the first electric motor 3.

  If it is determined in step S40 that the first electric motor 3 is disconnected (YES), the process proceeds to steps S34 to S38, the steering angle ratio control is stopped by the first electric motor 3, and the steering angle ratio control is performed. Perform the actions associated with the stop. If it is determined that no breakage has occurred in the first electric motor 3 (NO), the process proceeds to step S41, and it is determined whether or not a failure has occurred in the MOSFET of the inverter 63.

  If it is determined in step S41 that a failure has occurred in the MOSFET of the inverter 63 (YES), the process proceeds to steps S34 to S38, and the steering angle ratio control is stopped by the first electric motor 3, and this steering angle ratio control is stopped. Execute the action that accompanies If it is determined that a failure has not occurred in the MOSFET of the inverter 63 (NO), the process proceeds to step S42, and a normal fail-safe procedure is executed.

  Next, as shown in FIG. 11, in step S50, it is determined whether or not a control signal for taking over the steering angle ratio control from the first ECU 15 to the second ECU 74 is input to the second ECU 74. When a control signal for taking over the steering angle ratio control is input to the second ECU 74 (YES), the process proceeds to step S51, and it is determined whether or not the relative rotation angle is within a predetermined range. Further, when the control signal for taking over the steering angle ratio control is not input to the second ECU 74 (NO), the process proceeds to step S52 and normal assist control is executed. Each step shown in FIG. 11 is executed by the second ECU 74.

  If it is determined in step S51 that the relative rotation angle is within the predetermined range (YES), the process proceeds to step S53, the normal assist control is executed, the process returns to step S51, and the relative rotation angle is within the predetermined range. If not (NO), the process proceeds to step S54, the second electric motor 5 is operated so as to reduce the absolute value of the relative rotation angle, and the process proceeds to step S53. Here, the reason for proceeding from step S54 to step S53 is to continue the assist control by the second electric motor 5 even if the second ECU 74 takes over the steering angle ratio control.

[Effect of Example 1]
According to the vehicle steering apparatus 1 of the first embodiment, the first electric motor 3 of the VGRS 4 and the second electric motor 5 of the EPS 6 form one module 104.
In this way, the first and second electric motors 3 and 5 can be arranged close to each other by using the first and second electric motors 3 and 5 as one module 104. Therefore, the first and second electric motors 3 and 5 can be arranged close to each other. It is possible to improve the mountability of the vehicle steering device 1 as compared with the case where the vehicle steering devices 1 are separately arranged in the vehicle.

  In addition, the second electric motor 5 requires a large output in order to assist the turning of the steered wheels, and a large model has been conventionally used. The first electric motor 3 has an output capable of maintaining the steering angle ratio. It is sufficient if it is possible, and a small model has been adopted conventionally. However, such an unbalance of the sizes of the first and second electric motors 3 and 5 is also a factor of a decrease in the mountability of the vehicle steering apparatus 1.

  On the other hand, according to the vehicle steering apparatus 1 of the first embodiment, the first rotating member 13 that is rotationally driven by the output of the first electric motor 3 is mechanically connected to the steered wheels. The turning of the steered wheels can also be assisted by the output of the motor 3. Therefore, the size of the first and second electric motors 3 and 5 is reduced without lowering the assist capability by making the first electric motor 3 larger than the conventional one and making the second electric motor 5 smaller than the conventional one. Can be eliminated. And since the module 104 including the 1st, 2nd electric motors 3 and 5 becomes a well-balanced shape by eliminating the imbalance of the size of the 1st, 2nd electric motors 3 and 5, The mountability of the vehicle steering apparatus 1 can be improved.

The first and second rotating members 13 and 72 are also incorporated in the module 104.
Thus, before the first and second electric motors 3 and 5 and the first and second rotating members 13 and 72 are arranged in the vehicle, the meshing between the worm 23 and the worm wheel 27 and the worm 81 are performed in advance. The meshing with the worm wheel 85 can be adjusted. For this reason, the complexity of meshing adjustment can be eased and the number of work steps can be reduced.

The first and second electric motors 3 and 5 have the same shape and the same rating.
Thereby, since the motor model incorporated in the module 104 can be unified, the cost of the module 104 can be reduced.

The worms 23 and 81 have substantially the same diameter, and the worm wheels 27 and 85 have substantially the same diameter.
As a result, the worms 23 and 81 and the worm wheels 27 and 85 can be unified into one type, so that the cost of the module 104 can be reduced.

The first and second ECUs 15 and 74 are also incorporated in the module 104.
As a result, the ECU housing 107 can be combined into one, without providing the first and second ECUs 15 and 74 separately. For this reason, the cost of the module 104 can be reduced.

Further, the rotation angle detection means 14 and the torque detection means 73 are also incorporated in the module 104.
Thereby, the rotation angle detecting means 14 and the torque detecting means 73 can be adjusted in advance before being arranged in the vehicle. For this reason, the complexity of adjustment of the rotation angle detection means 14 and the torque detection means 73 can be reduced.

  The shaft-side detection means 30 includes a shaft-side nut-like member 36 that is restricted in rotation and moves up and down in the axial direction as the steering shaft 12 rotates, and a shaft-side magnet 33 assembled to the outer peripheral surface of the steering shaft 12. The shaft-side nut-like member 36 has two shaft-side magnetic field detecting means 34 and 35 mounted at an interval of 90 ° in the circumferential direction. The rotation angle of the steering shaft 12 is detected by detecting the change in the magnetic flux density accompanying the rotation by the two shaft-side magnetic field detection means 34 and 35.

  As a result, the shaft-side magnet 33 rotates without moving up and down in the axial direction, and the two shaft-side magnetic field detection means 34 and 35 move up and down in the axial direction without rotating. The detection signals output from each of the two shaft-side magnetic field detection means 34 and 35 are sinusoidal with respect to the rotation angle of the steering shaft 12, and the shaft-side magnet 33 and the two shaft-side magnetic field detection means 34. , 35 as the axial distance increases (that is, as the absolute value of the rotation angle increases or decreases from a predetermined specific value), the amplitude of the sine wave decreases. (See FIG. 5).

  For this reason, even if the absolute value of the rotation angle increases to either positive or negative from the phase and amplitude of the sine wave, it can be uniquely detected. Furthermore, since the two sinusoidal detection signals obtained from the two shaft-side magnetic field detection means 34 and 35 are out of phase by 90 °, the arc tangent based on the two detection signals is calculated, so that the steering shaft 12 The rotation angle can be calculated with extremely high accuracy.

  In addition, regarding the rotation angle of the first rotation member 13, by making the rotation member side detection unit 31 the same configuration as the shaft side detection unit 30, an absolute numerical value can be uniquely detected and a high value can be obtained. It can be calculated with accuracy.

  Further, the second ECU 74 stops control of the second electric motor 5 when a failure occurs in the EPS 6, and the first ECU 15 stops when the second ECU 74 stops control of the second electric motor 5 due to a failure of the EPS 6. The operation of the first electric motor 3 is controlled so as to assist the turning of the steered wheels by the output of the first electric motor 3.

  Since the first rotating member 13 is mechanically connected to the steered wheels, the output of the first electric motor 3 can be obtained even when the EPS 6 fails and the second electric motor 5 cannot assist the steered wheels. This makes it possible to assist the turning of the steered wheels. For this reason, it is possible to cope with a failure of the EPS 6 by executing the control process as described above by the first and second ECUs 15 and 74 without providing a spare for the second electric motor 5 or the like. As a result, in the vehicle steering apparatus 1 including both the VGRS 4 and the EPS 6, it is possible to eliminate an increase in cost and an increase in size due to the provision of a failure handling spare for the EPS 6.

  Further, the first ECU 15 stops the control of the first electric motor 3 when a failure occurs in a portion other than the rotation angle detection means 14 of the VGRS 4, and the second ECU 74 causes the first ECU 15 to change the rotation angle detection means 14 of the VGRS 4. When the control of the first electric motor 3 is stopped due to a failure of the part other than that, the operation of the second electric motor 5 is controlled so that the relative rotation angle is within a predetermined range by the output of the second electric motor 5.

  Since the second rotating member 72 is mechanically connected to the first rotating member 13, even when the VGRS 4 fails and the first electric motor 3 cannot change the steering angle ratio, the second electric motor 5 The steering angle ratio can be varied by the output. For this reason, the first and second ECUs 15 and 74 execute the control process as described above, so that it is possible to cope with a failure of the VGRS 4 excluding a failure of the rotation angle detection means 14.

[Modification]
According to the vehicle steering apparatus 1 of the first embodiment, the first and second electric motors 3 and 5, the first and second rotating members 13 and 72, the first and second ECUs 15 and 74, the rotation angle detecting means 14, and the torque Although the detection means 73 is incorporated in one module 104, whether or not a device other than the first and second electric motors 3 and 5 is incorporated in the module 104 depends on whether other devices other than the vehicle steering device 1 in the vehicle. And can be determined according to the mounting status of the equipment. For example, only the first and second electric motors 3 and 5 and the first and second ECUs 15 and 74 may be incorporated in the module 104, and the first and second electric motors 3 and 5 and the first and second rotating members 13 and 72 may be incorporated. May be incorporated into the module 104 only.

  Further, according to the vehicle steering apparatus 1 of the first embodiment, the rotation angle detection unit 14 rotates the shaft side detection unit 30 that detects the rotation angle of the steering shaft 12 and the rotation angle of the first rotation member 13. The member-side detection means 31 is provided to detect the relative rotation angle between the steering shaft 12 and the first rotation member 13. For example, the rotation member-side detection means 31 is turned from the first rotation member 13 to the steered wheel. It is attached to another member other than the first rotating member 13 arranged in the transmission path of the force to reach, and the relative rotation angle is detected from the rotation angle of this other member and the rotation angle of the steering shaft 12. Also good.

  Further, although the rotation angle detection means 14 is constituted by both the detection means of the shaft side detection means 30 and the rotation member side detection means 31, the rotation angle detection means 14 may be constituted by only one detection means. . For example, the rotating member side magnetic field detecting means 47 and 48 are provided so as to be rotatable together with the first rotating member 13, and the magnetic flux density of the magnetic field formed by the shaft side magnet 33 is detected by the rotating member side magnetic field detecting means 47 and 48. In this case, the relative rotation angle between the rotation angle of the steering shaft 12 and the rotation angle of the first rotation member 13 can be detected.

Further, by calculating the inverse sine (or inverse cosine) based on one detection signal so that the magnetic flux density is detected by only one of the shaft-side magnetic field detecting means 34 and 35, the steering shaft 12 The rotation angle may be detected.
Similarly, the rotating member-side magnetic field detecting means 47 and 48 can detect the rotation angle of the first rotating member 13 only with either one.

1 is an overall view of a vehicle steering apparatus. It is an internal sectional view showing the composition of the steering device for vehicles. It is an electric circuit diagram of a steering angle ratio variable device. It is a perspective view which shows the principal part of a rotation angle detection means. It is a correlation diagram which shows the correlation with the rotation angle and output value in the detection signal from a rotation angle detection means. It is an electric circuit diagram of an electric power steering device. It is a block diagram of a module. It is a flowchart which shows the control processing in 2nd ECU of alternative assist control by a 1st electric motor. It is a flowchart which shows the control processing in 1st ECU of the alternative assist control by a 1st electric motor. It is a flowchart which shows the control processing in 1st ECU of alternative steering angle ratio control by a 2nd electric motor. It is a flowchart which shows the control processing in 2nd ECU of alternative steering angle ratio control by a 2nd electric motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle steering device 2 Steering wheel 3 1st electric motor 4 VGRS (rudder angle ratio variable device)
5 Second electric motor 6 EPS (electric power steering device)
12 Steering shaft 13 First rotation member 14 Rotation angle detection means 15 First ECU (first control means)
72 Second rotating member 73 Torque detection means 74 Second ECU (second control means)
104 modules

Claims (2)

A steering angle ratio variable device that varies a transmission ratio between the steering angle of the steered wheel and the steered wheel by the output of the first electric motor;
In a vehicle steering apparatus comprising: an electric power steering device that assists the turning of the steered wheels by the output of a second electric motor different from the first electric motor;
The rudder angle ratio variable device is:
A steering shaft provided integrally with the steering wheel and rotated by a steering force applied to the steering wheel;
The steering shaft is rotatably incorporated, is rotated by the output of the first electric motor, and is mechanically connected to the steered wheel, and transmits the output of the first electric motor to the steered wheel. A first rotating member capable of
Rotation angle detection means for detecting a relative rotation angle between the steering shaft and the first rotation member;
First control means for controlling the operation of the first electric motor according to the relative rotation angle ,
The mechanical connection between the first rotating member and the steered wheel can assist the steering of the steered wheel by the output of the first electric motor,
The electric power steering device is
A second rotating member that is rotationally driven by the output of the second electric motor and mechanically connected to the first rotating member and the steered wheel, and transmits the output of the second electric motor to the steered wheel;
Torque detecting means for detecting torque transmitted from the first rotating member to the second rotating member;
Having a second control means for controlling the operation of the second electric motor according to the torque ,
The first electric motor and the second electric motor have substantially the same shape and the same rating, and constitute one module,
The second control means stops the control of the second electric motor when a failure occurs in the electric power steering device;
The first control means assists the turning of the steered wheels by the output of the first electric motor when the second control means stops the control of the second electric motor due to a failure of the electric power steering device. The vehicle steering apparatus characterized by controlling the operation of the first electric motor. The vehicle steering apparatus according to claim 1,
The first control means stops control on the first electric motor when a failure occurs in a portion other than the rotation angle detection means of the steering angle ratio variable device,
The second control means is configured such that when the first control means stops the control of the first electric motor due to a failure of a portion other than the rotation angle detection means of the steering angle ratio variable device, the second electric motor The vehicle steering apparatus characterized in that the operation of the second electric motor is controlled so that the relative rotation angle falls within a predetermined range by an output.

Images