JP5339095B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an angle sensor and an electric power steering device.

  Conventionally, an electric power steering apparatus that detects steering torque applied to a steering wheel of a vehicle with a torque sensor and generates an auxiliary steering torque corresponding to the steering force with an electric motor to steer a wheel has been put into practical use. Yes.

  Such an electric power steering apparatus is provided with an angle sensor for detecting the steering angle of the steering wheel (the rotation angle of the steering shaft). At present, a technique for estimating the steering angle of the steering without using an angle sensor based on information on the rotational speeds of the left and right wheels has also been proposed (see, for example, Patent Documents 1 and 2).

JP-A-11-180330 Japanese Patent Laid-Open No. 2003-14450

  In the conventional steering angle estimation techniques described in Patent Documents 1 and 2, when the control unit is de-energized due to an ignition off operation or the like, the steering angle calculated until immediately before is reset. There was a problem that the steering angle had to be newly learned from the next energization. For this reason, for example, when the steering wheel is steered when the ignition is off, the steering angle cannot be reflected at the next energization.

  The present invention has been made in view of such circumstances, and provides an angle sensor that can continue to acquire information related to the steering angle of the steering wheel even when the ignition is off, and an electric power steering apparatus including the angle sensor. The purpose is to do.

  In order to achieve the above object, an angle sensor according to the present invention includes angle information acquisition means for acquiring information related to a rotation angle of a shaft rotating around a predetermined axis, and is operated by externally supplied electric power and externally. Storage means for storing the information acquired by the angle information acquisition means when the control command is released, and outputting the information acquired by the angle information acquisition means to the outside. In addition.

  When such a configuration is adopted, when a control command is sent from the outside, information related to the rotation angle of the shaft can be output to the outside. On the other hand, when the control command is canceled, it is related to the rotation angle of the shaft. The information to be stored can be stored in the storage means. Therefore, even when information related to the rotation angle of the shaft is detected when the control command is released (for example, when the ignition is turned off), the information can be saved, and the saved information can be used later. It becomes.

  In the angle sensor according to the present invention, when the control command is sent after the information acquired by the angle information acquisition unit is stored in the storage unit, the information stored in the storage unit can be output to the outside. .

  By adopting such a configuration, information related to the rotation angle of the shaft stored in the storage means when the control command is released can be output to the outside when the control command is re-sent. The rotation angle of the shaft can be calculated.

  In the angle sensor according to the present invention, a motor rotation angle sensor that detects the rotation angle of the motor corresponding to the rotation angle of the shaft can be employed as the angle information acquisition means. In such a case, it is possible to employ a motor rotation angle sensor having a rotating member attached to the drive shaft of the motor and a magnetoresistive element portion that detects a magnetic field change of a magnetized portion fixed to the rotating member. it can. Further, the magnetoresistive element portion can be configured by a bridge circuit including at least one set of magnetic detection elements arranged so that the phase is shifted by 90 ° in accordance with the rotation angle of the rotating member. An MR element or a Hall element can be employed as the magnetic detection element.

  The electric power steering apparatus according to the present invention calculates an angle sensor that acquires information related to the rotation angle of the steering shaft and a steering angle of a steering wheel attached to the steering shaft based on information acquired by the angle sensor. And a control unit. The angle sensor according to the present invention is employed as the angle sensor. The control unit sends a control command to the angle sensor when the ignition is turned on, while releasing the control command when the ignition is turned off, and re-sends the control command when the ignition is turned on after the control command is released. The stored information is received and the rotation angle of the steering shaft when the control command is canceled is calculated.

  With this configuration, when the control command from the control unit is canceled when the ignition is turned off, information related to the rotation angle of the steering shaft obtained by the angle information obtaining means of the angle sensor is stored in the storage means of the angle sensor. can do. Therefore, even when the steering wheel is steered when the ignition is off, information related to the rotation angle of the steering shaft can be stored. Since the stored information can be output to the control unit when the control command is retransmitted, the steering angle of the steering wheel when the control command is released can be calculated.

  In the electric power steering apparatus according to the present invention, when the ignition is turned off, power can be supplied only from the storage battery to the angle sensor, and information acquired by the angle information acquisition unit of the angle sensor can be stored in the storage unit.

  By adopting such a configuration, information relating to the rotation angle of the steering shaft can be stored only by supplying power from the storage battery to the angle sensor when the ignition is off. Therefore, it is possible to reduce power consumption when the ignition is off.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the angle sensor which can continue acquiring the information relevant to the steering angle of a steering wheel also at the time of ignition off, and an electric power steering apparatus provided with the same.

It is a lineblock diagram showing the whole electric power steering device composition concerning an embodiment of the present invention. It is a block diagram which shows the functional structure of the angle sensor and control unit which are mounted in the electric power steering apparatus shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the outline of the configuration of the electric power steering apparatus 1 according to the present embodiment will be described with reference to FIG. The electric power steering device 1 acquires an angle sensor 10 that acquires information related to the rotation angle of the steering shaft 2 that rotates around a predetermined axis, and the steering angle of the steering wheel 3 that is attached to the steering shaft 2 by the angle sensor 10. And a control unit 20 that calculates based on the obtained information.

  The steering shaft 2 is connected to a wheel tie rod 7 via a reduction gear 4, universal joints 5A and 5B, and a pinion rack mechanism 6. The steering shaft 2 is provided with a torque sensor 8 that detects the steering torque T of the steering wheel 3. When the torsion bar 8 a is twisted by the steering force T of the steering wheel 3, the torque sensor 8 responds to the steering torque T. The electrical signal is output to the control unit 20. An electric motor 9 for assisting the steering torque of the steering wheel 3 is connected to the steering shaft 2 via a reduction gear 4, and the electric motor 9 is provided with an angle sensor 10. The configuration of the angle sensor 10 will be described in detail later.

  Electric power is supplied to the control unit 20 from a battery (storage battery) 31 and an ignition signal is input via an ignition key 32. The control unit 20 calculates a current command value I of the steering assist command based on the steering torque T detected by the torque sensor 8 and the vehicle speed V detected by the vehicle speed sensor 33, and electric control is performed based on the calculated current command value I. The current supplied to the motor 9 is controlled. The configuration of the control unit 20 will be described in detail later.

  Next, functional configurations of the angle sensor 10 and the control unit 20 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 2, the angle sensor 10 is operated by electric power supplied from the battery 31, and includes a motor rotation angle sensor 11 that detects the rotation angle of the electric motor 9. The motor rotation angle sensor 11 acquires information related to the rotation angle of the steering shaft 2 (rotation angle of the electric motor 9 corresponding to the rotation angle of the steering shaft 2 on a one-to-one basis). Function as. The angle sensor 10 outputs information (angle signal) of the rotation angle detected by the motor rotation angle sensor 11 to the control unit 20 when a control command is sent from the control unit 20.

  The motor rotation angle sensor 11 in the present embodiment detects a magnetic field change between a rotating member attached to the drive shaft of the electric motor 9 and a magnetized portion (S-pole magnet and N-pole magnet) fixed to the rotating member. And a magnetoresistive element portion. The rotating member rotates at a constant cycle while synchronizing with the rotation of the drive shaft of the electric motor 9. The magnetoresistive element portion is configured by a bridge circuit including at least one set of magnetic detection elements arranged so that the phase is shifted by 90 ° according to the rotation angle of the rotating member. An MR element or a Hall element can be employed as the magnetic detection element. The thus configured motor rotation angle sensor 11 outputs sine wave (sin θ) and cosine wave (cos θ) signals corresponding to the rotation angle θ of the electric motor 9 to the control unit 20.

  The angle sensor 10 also has an integrated circuit (ASIC) 12 that stores information detected by the motor rotation angle sensor 11 when a control command sent from the control unit 20 is canceled. The integrated circuit 12 functions as storage means in the present invention. The integrated circuit 12 also has a function of calculating the rotation angle of the steering shaft 2 based on information on the rotation angle θ of the electric motor 9 detected by the motor rotation angle sensor 11 (sine wave and cosine wave signals). The rotation angle of the steering shaft 2 calculated in this way can also be stored. Further, the integrated circuit 12 has a communication function for outputting the stored information to the control unit 20 when a control command is sent from the control unit 20 after storing the information detected by the motor rotation angle sensor 11. .

  As shown in FIG. 2, the control unit 20 is operated by electric power supplied from the battery 31, and includes an MCU 21 that performs various arithmetic processes. The MCU 21 sends a control command to the angle sensor 10 and receives rotation angle information (angle signal) output from the angle sensor 10 when an ignition-on signal is sent via the ignition key 32. Then, the rotation angle of the steering shaft 2 is calculated by executing an arc tangent function (arctan θ) based on the received information.

  Further, when the ignition-on signal is canceled, the MCU 21 cuts off the connection of the switch 22 to stop the power supply from the battery 31 to the MCU 21 and also sends the control to the angle sensor 10 when the ignition is on. Release the command. Thereby, when the ignition is turned off, various arithmetic processes by the MCU 21 are stopped. On the other hand, the electric power is supplied from the battery 31 to the angle sensor 10 even when the ignition is off (when the control command is released). Therefore, the angle sensor 10 stores the information detected by the motor rotation angle sensor 11 when the ignition is turned off in the integrated circuit 12 as described above.

  After such an ignition-off period, when the ignition-on signal is retransmitted, the MCU 21 retransmits the control command to the angle sensor 10 and is stored in the integrated circuit 12 of the angle sensor 10. Information is received, and arithmetic processing is executed based on the received information. Thereby, the MCU 21 can calculate the rotation angle of the steering shaft 2 (the steering angle of the steering wheel 3) during the ignition-off period.

  In the angle sensor 10 according to the above embodiment, when a control command is sent from the outside (control unit 20), information related to the rotation angle of the steering shaft 2 can be output to the outside. When is released, information related to the rotation angle of the steering shaft 2 can be stored in the integrated circuit 12. Therefore, even when information related to the rotation angle of the steering shaft 2 is detected when the control command is released (ignition off), the information can be saved, and the saved information can be used later. It becomes possible.

  Further, in the angle sensor 10 according to the above embodiment, information related to the rotation angle of the steering shaft 2 stored in the integrated circuit 12 when the control command is released is output to the outside (control unit 20) when the control command is retransmitted. Therefore, the rotation angle of the steering shaft 2 when the control command is released can be calculated using this information.

  Further, in the electric power steering apparatus 1 according to the above embodiment, when the control command from the control unit 20 is canceled when the ignition is turned off, the electric motor 9 detected by the motor rotation angle sensor 11 of the angle sensor 10 is used. Information on the rotation angle can be stored in the integrated circuit 12 of the angle sensor 10. Therefore, even when the steering wheel 3 is steered when the ignition is off, information related to the rotation angle of the steering shaft 2 (information about the rotation angle of the electric motor 9) can be stored. Since the stored information is output to the control unit 20 when the control command is retransmitted, the steering angle of the steering wheel 3 when the control command is released can be calculated.

  Further, in the electric power steering apparatus 1 according to the above-described embodiment, information relating to the rotation angle of the steering shaft 2 can be stored only by supplying power from the battery 31 to the angle sensor 10 when the ignition is off. . Therefore, it is possible to reduce power consumption when the ignition is off.

  In the above embodiment, the example in which the motor rotation angle sensor 11 that detects the rotation angle information of the electric motor 9 is employed as the angle information acquisition unit of the angle sensor has been described. However, the configuration of the angle information acquisition unit is as follows. It is not limited to this. For example, the steering shaft 2 includes a rotating member that is attached to the steering shaft 2 itself and rotates in synchronization with the steering shaft 2, and a magnetoresistive element portion that detects a magnetic field change of a magnetized portion fixed to the rotating member. A rotation angle sensor that outputs sine wave and cosine wave signals corresponding to the rotation angle can be employed as the angle information acquisition means.

  In the above embodiment, the example in which the present invention is applied to the angle sensor for the electric power steering apparatus that acquires information related to the rotation angle of the steering shaft of the vehicle has been shown. However, the scope of the present invention is not limited to this. The present invention can be applied to various angle sensors that acquire information related to the rotation angle of the shaft.

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus 2 ... Steering shaft 3 ... Steering wheel 10 ... Angle sensor 11 ... Motor rotation angle sensor (Angle information acquisition means)
12 ... Integrated circuit (memory means)
20 ... Control unit 31 ... Battery (storage battery)

Claims (4)

An electric power steering system comprising: an angle sensor that acquires information related to a rotation angle of a steering shaft; and a control unit that calculates a steering angle of a steering wheel attached to the steering shaft based on the information acquired by the angle sensor. A device,
The angle sensor, and the angle information obtaining means for obtaining information related to the rotation angle of the steering shaft, a storage means for storing the information acquired by the angular information acquisition means when the control command is canceled, the The information obtained by the angle information acquisition means is output to the outside when the control command is sent from the outside and operated by the power supplied from the outside, while the information obtained by the angle information acquisition means is Configured to output the information stored in the storage means to the outside when the control command is sent after being stored in the storage means;
The control unit sends a control command to the angle sensor when the ignition is turned on, while releasing the control command when the ignition is turned off, and resends the control command when the ignition is turned on after the control command is released. Receiving the information stored in the storage means of the sensor and calculating the rotation angle of the steering shaft when the control command is canceled,
Power is supplied only from the storage battery to the angle sensor at the time of ignition off, and the information acquired by the angle information acquisition means of the angle sensor is stored in the storage means of the angle sensor.
Electric power steering device. The angle information acquisition means is a motor rotation angle sensor that detects a rotation angle of a motor corresponding to a rotation angle of the shaft.
The electric power steering apparatus according to claim 1. The motor rotation angle sensor includes a rotary member mounted on the drive shaft of the motor, and the element terminal portion that detect a magnetic field variation magnetized part which is fixed to the rotary member, the front Kimoto child The unit is configured by a bridge circuit including at least one set of magnetic detection elements arranged so that the phase is shifted by 90 ° according to the rotation angle of the rotating member.
The electric power steering apparatus according to claim 2. The magnetic detection element is an MR element or a Hall element.
The electric power steering apparatus according to claim 3.

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