JP2009120159A - Electric power steering device - Google Patents

Electric power steering device Download PDF

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Publication number
JP2009120159A
JP2009120159A JP2007299448A JP2007299448A JP2009120159A JP 2009120159 A JP2009120159 A JP 2009120159A JP 2007299448 A JP2007299448 A JP 2007299448A JP 2007299448 A JP2007299448 A JP 2007299448A JP 2009120159 A JP2009120159 A JP 2009120159A
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power source
circuit
auxiliary power
electric motor
electric
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JP2007299448A
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Japanese (ja)
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JP5277614B2 (en
Inventor
Shigeki Nagase
茂樹 長瀬
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Jtekt Corp
株式会社ジェイテクト
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Abstract

<P>PROBLEM TO BE SOLVED: To prevent characteristic deterioration of an auxiliary power source due to thermal effects by devising arrangement positions of the auxiliary power source and charge/discharge circuits. <P>SOLUTION: The electric power steering device 1 is provided with an electric motor 40 to generate steering assisting force, a main power source 11 to feed power to the electric motor 40, a drive circuit 15 to drive the electric motor 40 by power of a main power source 11, a control circuit 24 to control the drive circuit 15 the auxiliary power source 12 charged by the main power source 11 to be able to feed power to the electric motor 40, and the charge/discharge circuits 13 and 14 controlled by a control circuit 24 to charge/discharge the auxiliary power source 12. The electric motor 40, the drive circuit 15, the control circuit 24, and the charge and discharge circuits 13 and 14 are disposed in an engine room, while the auxiliary power source 12 is disposed in a cabin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that generates a steering assist force by an electric motor.

The electric power steering device generates steering assist force by driving the electric motor only when necessary without using the output of the engine, so it has high efficiency and little influence on fuel consumption. ing. In recent years, demand for large vehicles has been increasing due to fuel efficiency considerations.
However, in a large vehicle, since the output power of the on-vehicle battery is reaching the limit even in the present situation, it is necessary to further increase the output in order to apply the electric power steering device.

As one of high output methods, a technique has been developed in which an auxiliary power source capable of supplying electric power to an electric motor is added to an in-vehicle battery (see Patent Document 1 below). In Patent Document 1, a secondary battery such as an electric double layer capacitor (capacitor) or a lithium ion battery is used as an auxiliary power source.
JP 2003-320942 A

For a large vehicle, a rack assist type power steering device that applies thrust to a rack shaft is usually used. Therefore, when this power steering device is simply electrified, the electric motor, auxiliary power supply, motor drive circuit, charge / discharge circuit for auxiliary power supply, etc., which are electrically connected to each other, are all arranged near the rack shaft. Can be considered.
However, an auxiliary power source, for example, an electric double layer capacitor, has a use temperature range of about −20 ° C. to 60 ° C., whereas the engine room where the rack shaft is arranged has a high temperature exceeding 80 ° C. There is a case. For this reason, if an auxiliary power source is disposed in the engine room, there is a possibility that the characteristics may be deteriorated due to thermal effects, which is not preferable.

  An object of the present invention is to provide an electric power steering device that can prevent deterioration of the characteristics of an auxiliary power source due to thermal influences by devising an arrangement location of an auxiliary power source and a charge / discharge circuit.

  The electric power steering apparatus of the present invention includes an electric motor that generates a steering assist force, a main power source that supplies electric power to the electric motor, an auxiliary power source that can supply electric power to the electric motor, and the main power source. And a drive circuit for driving the electric motor by the power of the auxiliary power source, a control circuit for controlling the drive circuit, and a charge / discharge circuit controlled by the control circuit to charge / discharge the auxiliary power source. The electric motor, the drive circuit, the control circuit, and the charge / discharge circuit are disposed in an engine room of the vehicle, and the auxiliary power source is disposed in a vehicle compartment partitioned from the engine room. It is characterized by.

According to this configuration, since the auxiliary power source is disposed in the vehicle compartment partitioned from the engine room, it is possible to prevent deterioration of characteristics due to high temperatures.
A charge / discharge circuit that charges and discharges the auxiliary power supply is connected to a drive circuit and a control circuit in order to supply the electric power of the auxiliary power supply to the electric motor. For this reason, the charging / discharging circuit is not arranged in the vehicle compartment together with the auxiliary power supply, but is arranged in the engine room together with the electric motor, the driving circuit, and the control circuit, so that the charging / discharging circuit, the driving circuit, and the control circuit are mutually connected. It is sufficient to connect the charging / discharging circuit and the auxiliary power source with a small number of additional parts such as a harness and a connector. Further, the charge / discharge circuit can be integrated into one unit as an electronic control unit (ECU) together with the drive circuit and the control circuit.

  According to the present invention, it is possible to prevent the deterioration of the characteristics of the auxiliary power source due to the influence of heat.

  FIG. 1 is a schematic diagram of an electric power steering apparatus 1 according to an embodiment of the present invention. The apparatus 1 is mounted on, for example, an automobile and corresponds to a steering operation of a driver applied to a steering wheel (steering member) 2. A steering shaft 4 for changing the direction of the tire (steering wheel) 3 is provided. A steering gear 7 is connected to the lower end of the steering shaft 4 via a universal joint 5 and an intermediate shaft 6. The steering gear 7 is of a rack and pinion type including a pinion shaft 8 and a rack shaft 9, and the pinion shaft 8 is connected to the universal joint 5 at the upper end and includes pinion teeth 8a at the lower portion. The rack shaft 9 includes rack teeth 9a that mesh with the pinion teeth 8a.

  The rack shaft 9 is supported in the housing 31 so as to be movable in the axial direction (left-right direction), and the tire 3 is connected to both ends of the rack shaft 8 in the axial direction via tie rods 32 and knuckle arms 33. The pinion shaft 8 is supported by the housing 31 so as to be rotatable about its axis.

  In the above-described configuration, when the steering wheel 2 is rotated for steering, the pinion shaft 8 connected via the steering shaft 4, the intermediate shaft 6 and the like rotates, and this rotation is caused by the pinion teeth 8a and the rack teeth 9a. Is converted into the movement of the rack shaft 9 in the axial direction. The movement of the rack shaft 9 is transmitted to the left and right knuckle arms 33 via the tie rods 32, and the left and right tires 3 are steered in the operation direction of the steering wheel 2 by pushing and pulling these knuckle arms 33. .

  The electric power steering apparatus 1 according to the present embodiment is of a rack assist type that transmits the steering assist force of the electric motor 40 to the rack shaft 9. The rack-assist type electric power steering apparatus 1 includes a rotating body 41 that is externally fitted on the outer peripheral surface of the rack shaft 9 so as to be relatively rotatable, and is rotatably supported by a housing 31 via a bearing. A ball screw mechanism 42 formed between the rack shaft 9, an electric motor 40 including a brushless motor supported by the housing 31, and a transmission including a bevel gear or the like that transmits the rotational power of the electric motor 40 to the rotating body 41. And a mechanism 43. The rotational power of the electric motor 40 is transmitted to the rotating body 41 via the transmission mechanism 43, and the rotation of the rotating body 41 is converted into the axial thrust of the rack shaft 9 by the ball screw mechanism 42.

  The motor control device for driving and controlling the electric motor 40 includes an electronic control unit (ECU) 10, and a main power supply 11 and an auxiliary power supply 12 that supply electric power to the electric motor 40. The ECU 10 and the main power supply 11 are arranged in the engine room together with the rack shaft 9 and the electric motor 40, and the auxiliary power supply 12 is arranged in a vehicle compartment partitioned from the engine room by a partition wall 50. In particular, the ECU 10 is disposed in the vicinity of the electric motor 40 and is connected to the electric motor 40 and the main power supply 11 by electric wiring. The ECU 10 receives a detection signal from the torque sensor 25 that detects the steering torque and a detection signal from the vehicle speed sensor 26 that detects the vehicle speed.

  FIG. 2 is a schematic block circuit diagram of the motor control device, and the ECU 10 includes a charging circuit 13, a discharging circuit 14, a motor driving circuit 15, and a control circuit 24. The main power supply 11 is composed of an in-vehicle battery and an alternator, and supplies power to various electric devices of the vehicle. The in-vehicle battery is charged by an alternator. The main power supply 11 is connected to the motor drive circuit 15 via the power feeding line 16 and the second changeover switch 22.

  The auxiliary power supply 12 is configured by an electric double layer capacitor, is charged by the main power supply 11, and supplies power to the motor 40 of the electric power steering apparatus 1 as necessary. One terminal 12 a of the auxiliary power source 12 is connected to a charging electric circuit 18 connected to the power supply electric circuit 16 and a discharging electric circuit 19. On the other hand, the other terminal 12 b of the auxiliary power source 12 is connected to the power feeding circuit 16 or the ground potential via the first changeover switch 20. The charging circuit 18 is provided with a diode 21 for preventing backflow, and the diode 21 and the first changeover switch 20 constitute a charging circuit 13.

The discharge electric path 19 is connected to the motor drive circuit 15 via the second changeover switch 22. The second change-over switch 22 switches and connects the motor drive circuit 15 to the power supply electric line 16 and the discharge electric line 19, and the discharge circuit 14 is configured by the second change-over switch 22.
The motor driving circuit 15, the charging circuit 13, and the discharging circuit 14 operate in response to a control signal from the control circuit 24. The control circuit 24 receives input of detection signals from the torque sensor 25 and the vehicle speed sensor 26, and generates a suitable steering assist force in accordance with the detection signals. The motor drive circuit 15, the charging circuit 13, and the discharging circuit 14 is controlled to drive the motor 40.

  When the contacts p1 and p2 are connected by the first changeover switch 20 constituting the charging circuit 13 (shown by a solid line a), the other terminal 12b of the auxiliary power supply 12 is connected to the ground potential. In this state, when the contacts p4 and p5 are connected by the second changeover switch 22 constituting the discharge circuit 14 (shown by a solid line c), the power feeding circuit 16 is connected to the motor drive circuit 15. As a result, the electric power of the main power supply 11 is supplied to the motor drive circuit 15 through the power supply circuit 16, and the auxiliary power supply 12 is charged by the main power supply 11 through the charging electric circuit 18. Therefore, the power of the auxiliary power supply 12 is not supplied to the motor drive circuit 15.

  On the other hand, when the contacts p1 and p3 are connected by the first changeover switch 20 (indicated by a dotted line b), the other terminal 12b of the auxiliary power supply 12 is connected to the main power supply 11 in series. In this state, when the contacts p4 and p6 are connected by the second changeover switch 22 (indicated by a dotted line d), the discharge electric path 19 is connected to the motor drive circuit 15, and the electric power of the main power supply 11 and the auxiliary power supply 12 is driven by the motor. It is supplied to the circuit 15.

  That is, when the first and second change-over switches 20 and 22 are switched to the positions a and c indicated by solid lines, the auxiliary power supply 12 is charged, and the first and second change-over switches 20 and 22 are indicated by positions b and d indicated by dotted lines. When switched to, the auxiliary power supply 12 is discharged.

  In the above configuration, when the required steering assist force is relatively small, the control circuit 24 switches the first and second changeover switches 20 and 22 to the positions a and c indicated by solid lines to charge the auxiliary power supply 12. Put it in a state. Thereby, the electric power of the main power supply 11 is supplied to the motor drive circuit 15, and the motor drive circuit 15 drives the motor 40 based on the control signal from the control circuit 24.

  On the other hand, when the required steering assist force is relatively large and cannot be covered by the main power supply 11 alone, the control circuit 24 moves the first and second changeover switches 20 and 22 to positions b and d indicated by dotted lines, respectively. By switching, the auxiliary power supply 12 is discharged. As a result, in the state where the main power supply 11 and the auxiliary power supply 12 are connected in series with each other, both electric powers are supplied to the motor drive circuit 15.

  As described above, in the electric power steering apparatus 1 according to the present embodiment, the auxiliary power source 12 is disposed in the vehicle compartment, so that the electric power steering device 1 is not exposed to the high temperature in the engine room, and is defined in the use temperature range. Auxiliary power supply 12 can be used. Therefore, the characteristics of the auxiliary power supply 12 are hardly deteriorated by the temperature environment. The charging / discharging circuits 13 and 14 for charging and discharging the auxiliary power supply 12 are not arranged in the vehicle compartment together with the auxiliary power supply 12 but in the engine room, and are incorporated in the ECU 10 together with the motor drive circuit 15 and the control circuit 24. Therefore, there is no need for connecting parts such as a harness necessary for arranging these separately apart from each other, and the auxiliary power supply 12 and the charge / discharge circuits 13 and 14 in the ECU 10 are connected to the connector 27 (FIG. 2)), it is sufficient if the structure is detachably connected. Therefore, the increase in the number of parts accompanying the arrangement of the auxiliary power supply 12 in the vehicle compartment can be suppressed.

The present invention is not limited to the above-described embodiment, and can be appropriately changed in design.
For example, the auxiliary power source 12 is not limited to an electric double layer capacitor, and may be a secondary power source such as a lithium ion battery. As the first and second changeover switches 20 and 22 constituting the charging circuit 13 and the discharging circuit 14, semiconductor switching elements such as MOS-FET, BJT, and IGBT can be used.

In addition, a means for detecting a failure (for example, a sudden voltage drop) of the on-vehicle battery constituting the main power supply 11 is provided, and the main power supply 11 has failed in the auxiliary power supply 12 by connecting this detection means to the control circuit 24. It can also function as a backup power source.
The electric power steering device of the present invention is not limited to the rack assist type, but may be another type in which an electric motor or the like is disposed in the engine room, for example, a pinion assist type. Further, the arrangement of the torque sensor 25 and the vehicle speed sensor 26 is not particularly limited, and can be appropriately arranged according to the type of the electric power steering apparatus.

It is a mimetic diagram of an electric power steering device concerning an embodiment of the invention. It is a block circuit diagram of a motor control device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 4 Motor 11 Main power supply 12 Auxiliary power supply 13 Charging circuit 14 Discharge circuit 15 Motor drive circuit 24 Control circuit

Claims (1)

  1. An electric motor that generates steering assist force;
    A main power supply for supplying power to the electric motor;
    An auxiliary power source capable of supplying power to the electric motor;
    A drive circuit for driving the electric motor by the power of the main power source and the auxiliary power source;
    A control circuit for controlling the drive circuit;
    A charge / discharge circuit controlled by the control circuit to charge / discharge the auxiliary power source,
    The electric motor, the drive circuit, the control circuit, and the charging / discharging circuit are disposed in an engine room of a vehicle, and the auxiliary power source is disposed in a vehicle compartment partitioned from the engine room. Electric power steering device.
JP2007299448A 2007-11-19 2007-11-19 Electric power steering device Active JP5277614B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2007299448A JP5277614B2 (en) 2007-11-19 2007-11-19 Electric power steering device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2007299448A JP5277614B2 (en) 2007-11-19 2007-11-19 Electric power steering device

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JP2009120159A true JP2009120159A (en) 2009-06-04
JP5277614B2 JP5277614B2 (en) 2013-08-28

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0886825A (en) * 1994-09-19 1996-04-02 Mazda Motor Corp Drive circuit controller for automobile
JP2001196770A (en) * 2000-01-12 2001-07-19 Omron Corp Control unit
JP2003320942A (en) * 2002-04-26 2003-11-11 Nsk Ltd Electric power steering apparatus
JP2004260903A (en) * 2003-02-25 2004-09-16 Denso Corp In-vehicle power supply system
JP2004289892A (en) * 2003-03-19 2004-10-14 Denso Corp In-vehicle power supply system
JP2004350426A (en) * 2003-05-22 2004-12-09 Denso Corp Power supply system for vehicle
JP2005075028A (en) * 2003-08-28 2005-03-24 Auto Network Gijutsu Kenkyusho:Kk Wiring structure for vehicle
JP2007253873A (en) * 2006-03-24 2007-10-04 Mazda Motor Corp Steering unit arrangement structure of vehicle

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0886825A (en) * 1994-09-19 1996-04-02 Mazda Motor Corp Drive circuit controller for automobile
JP2001196770A (en) * 2000-01-12 2001-07-19 Omron Corp Control unit
JP2003320942A (en) * 2002-04-26 2003-11-11 Nsk Ltd Electric power steering apparatus
JP2004260903A (en) * 2003-02-25 2004-09-16 Denso Corp In-vehicle power supply system
JP2004289892A (en) * 2003-03-19 2004-10-14 Denso Corp In-vehicle power supply system
JP2004350426A (en) * 2003-05-22 2004-12-09 Denso Corp Power supply system for vehicle
JP2005075028A (en) * 2003-08-28 2005-03-24 Auto Network Gijutsu Kenkyusho:Kk Wiring structure for vehicle
JP2007253873A (en) * 2006-03-24 2007-10-04 Mazda Motor Corp Steering unit arrangement structure of vehicle

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