JP2008183988A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of providing the excellent steering feeling irrespective of the change in the weight distribution in the longitudinal direction of a vehicle. <P>SOLUTION: In the electric power steering device 11, the set value R1 of a leveling dial 37 is detected as an alternative value of the inclination of the irradiation direction of a headlamp 60 with respect to a vehicle body 10A, and the current command value I1 for assistance is corrected (increased/decreased) by the assist gain G1 determined based on the dial set value R1. Thus, even when the weight distribution in the longitudinal direction of the vehicle 10 is changed (the load on front wheels 50, 50 is increased/decreased), the assist force is increased/decreased according thereto, and any influence on the steering feeling can be suppressed. In other words, the excellent steering feeling can be provided irrespective of the change of the weight distribution in the longitudinal direction of the vehicle 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that outputs an assist force for assisting steering of a steering wheel.

As a conventional electric power steering device, a motor current command value is determined corresponding to the steering torque applied to the rotating shaft of the steering wheel and the vehicle speed of the vehicle, and a drive current corresponding to the motor current command value is applied to the steering motor. A device that outputs an assist force for assisting steering of the steering wheel is known (for example, see Patent Document 1).
JP-A-2005-239011 (paragraphs [0031] to [0032])

  By the way, the above-described motor current command value is determined, for example, from a current command value calculation map in which the steering torque and the vehicle speed are stored in association with the motor current command value. The current command value calculation map is normally set so that an optimal steering feeling can be obtained when the weight distribution in the front-rear direction of the vehicle is the weight distribution in an average riding state. Similarly, when the motor current command value is determined by an arithmetic expression instead of the current command value calculation map, the optimum steering feeling is obtained when the weight distribution in the longitudinal direction of the vehicle is the weight distribution in the average riding state. Is set to be obtained. However, regardless of which method is used to determine the motor current command value, the above-described conventional electric power steering apparatus does not correct the motor current command value by changing the weight distribution in the front-rear direction of the vehicle. For this reason, when the weight distribution of the vehicle changes due to people getting on and off, loading and unloading, etc., the steering feeling may become uncomfortable.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric power steering apparatus capable of giving a good steering feeling regardless of changes in weight distribution in the longitudinal direction of the vehicle.

  The electric power steering device (11) according to the first aspect of the invention, which has been made to achieve the above object, changes the direction of irradiation of the headlamp (60) according to the inclination of the vehicle body (10A) in the front-rear direction. In the electric power steering device (11) that is provided in the vehicle (10) that can be tilted vertically with respect to the steering wheel (33) and that assists the steering of the steering wheel (33), the vehicle speed (V) And an assist force determining means (43, S2) for determining a target value of the assist force according to the steering torque (T1) for steering the steering wheel (33), and irradiation of the headlamp (60) to the vehicle body (10A) The tilt amount detecting means (41, 63) for detecting the tilt amount of the direction, and the tilt amount in the irradiation direction detected by the tilt amount detecting means (41, 63) increases downward with respect to the vehicle body (10A). Accordingly, there is provided target value correcting means (45, 46, S4, S5) for correcting the assist force so that the target value becomes small, and the assist force corrected by the target value correcting means (45, 46, S4, S5) is provided. It is characterized in that the assist force is output according to the target value.

  According to a second aspect of the present invention, in the electric power steering apparatus (11) according to the first aspect, the vehicle (10) has an operation portion (37) capable of manually setting an amount of inclination of the irradiation direction with respect to the vehicle body (10A). The inclination amount detecting means (41, 63) is characterized in that the setting value (R1) by the operation unit (37) is detected as a substitute value for the inclination amount in the irradiation direction.

  According to a third aspect of the present invention, in the electric power steering apparatus (11) according to the first aspect, the headlamp (60) reflects light from the light source forward and tilts in the vertical direction with respect to the vehicle body (10A). The tilt amount detection means (41, 63) includes a possible reflector (61), and the rotation position of the motor (62) that tilts the reflector (61) with respect to the vehicle body (10A) is used as a substitute value for the tilt amount in the irradiation direction. As a feature.

  According to a fourth aspect of the present invention, in the electric power steering apparatus (11) according to any one of the first to third aspects, the target value correcting means (45, 46) includes an inclination amount in the irradiation direction, an assist gain (G1), and Is associated with the assist gain correspondence map (mp21, mp22), and based on the assist gain correspondence map (mp21, mp22), the inclination amount in the irradiation direction detected by the inclination amount detection means (41, 63) is used. The assist gain (G1) is determined, and correction is performed by multiplying the determined assist gain (G1) by a target value of the assist force.

  When the weight distribution in the vehicle front-rear direction changes due to people getting on and off or loading and unloading luggage, the frictional resistance between the steered wheels and the road surface increases and decreases, and the force required to steer the steered wheels (that is, the steering force and assist force) The combined force is also increased or decreased. Specifically, when the weight distribution at the rear of the vehicle is increased, the vehicle body is tilted backward, and the front portion of the vehicle is lifted to reduce the load applied to the steered wheels. Further, since the irradiation direction of the headlamp is shifted upward when the front portion of the vehicle body is lifted, the irradiation direction of the headlamp is inclined downward with respect to the vehicle body in order to correct the shift.

  On the other hand, according to the present invention, as the amount of inclination of the headlamp in the irradiation direction with respect to the vehicle body increases downward, in other words, as the load applied to the steered wheels decreases, the target value correcting means reduces the assist force. Correct so that the target value becomes smaller. As a result, even if the weight distribution at the rear of the vehicle increases due to people, luggage, etc., the influence on the steering feeling can be suppressed. That is, good steering feeling can be provided regardless of changes in weight distribution in the longitudinal direction of the vehicle. Note that the amount of inclination of the irradiation direction of the headlamp may be manually adjusted by the driver, or may be automatically adjusted by detecting the inclination of the vehicle body.

  Here, as in the second aspect of the invention, when the vehicle is provided with an operation unit that can manually set the amount of inclination of the irradiation direction of the headlamp, the set value by the operation unit is set in the irradiation direction. As a substitute value of the tilt amount, it may be detected by the tilt amount detecting means.

  Further, as in the third aspect of the invention, when the reflector provided in the headlamp is tilted with respect to the vehicle body by the motor to tilt the irradiation direction in the vertical direction, the rotational position of the motor is set in the irradiation direction. As a substitute value of the tilt amount, it may be detected by the tilt amount detecting means.

  According to the invention of claim 4, when the weight distribution at the rear of the vehicle increases and the load applied to the steered wheels decreases, the target value correcting means assists from the amount of inclination in the irradiation direction based on the assist gain correspondence map. The gain is determined, and the determined assist gain is multiplied by the assist force target value to correct the assist force target value to be smaller than before the weight distribution at the rear of the vehicle increases.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. A vehicle 10 shown in FIG. 1 includes an electric power steering device 11 according to the present invention, and assists a steering operation by a driver with a steering motor 19 to correspond to front wheels 50 and 50 ("steering wheels" according to the present invention). Can be steered). Specifically, as shown in FIG. 1, the inter-steering wheel shaft 16 is passed between the pair of front wheels 50, 50. The inter-steering wheel shaft 16 is inserted into a cylindrical housing 18 fixed to the vehicle body 10A of the vehicle 10, and both ends of the steered wheel shaft 16 are connected to the front wheels 50, 50 via tie rods 17, 17, respectively. Has been. Moreover, the large diameter part 18D is provided in the intermediate part of the axial direction of the cylindrical housing 18, and the steering motor 19 is incorporated in the large diameter part 18D. The steered motor 19 includes a stator 20 that is fitted and fixed to the inner surface of the cylindrical housing 18, and a cylindrical rotor 21 that is loosely fitted inside the stator 20. The inter-steering wheel shaft 16 passes through the inside of the rotor 21. In addition, a rotational position sensor 25 (for example, an encoder or a resolver) for detecting the rotational position of the rotor 21 is provided at one end of the large-diameter portion 18D of the cylindrical housing 18.

  A ball nut 22 is assembled on the inner surface of the rotor 21, and a ball screw portion 23 is formed at an intermediate portion in the axial direction of the inter-steering wheel shaft 16. A ball screw mechanism 24 is constituted by the ball nut 22 and the ball screw portion 23, and when the ball nut 22 rotates together with the rotor 21, the ball screw portion 23 moves linearly with respect to the cylindrical housing 18, thereby rotating the front wheels 50, 50. Rudder.

  A rack 30 is formed on one end of the inter-steering wheel shaft 16, and a pinion 31 provided at the lower end of the steering shaft 32 is engaged with the rack 30.

  A handle 33 is attached to the upper end portion of the steering shaft 32. Further, a steering angle sensor 34 is attached to a position near the upper end of the steering shaft 32, and the rotation angle of the steering shaft 32 (that is, the steering angle θ 2 of the handle 33) is detected by the steering angle sensor 34.

  A steering torque sensor 35 is attached to a portion of the steering shaft 32 below the steering angle sensor 34. The steering torque sensor 35 includes a torsion spring (not shown) that is torsionally deformed by the steering torque T1 applied to the steering shaft 32, and a pair of resolvers (not shown) for detecting the rotation angles of both ends of the torsion spring. The steering torque T1 applied to the steering shaft 32 can be detected by the steering of the handle 33 in accordance with the difference between the rotation angles detected by the two resolvers. A vehicle speed sensor 36 for detecting the vehicle speed V based on the rotation of the front wheel 50 is provided in the vicinity of the front wheel 50.

  Further, in the vehicle 10, the irradiation direction (optical axis) of the headlamp 60 (corresponding to the “headlight” according to the present invention) provided at the front portion of the vehicle body 10A is set in the vertical direction with respect to the vehicle body 10A. A headlamp leveling device that can be tilted is installed.

  Specifically, as shown in FIG. 4A, a leveling dial 37 (in the present invention) in which the irradiation direction of the headlamp 60 can be manually adjusted up and down is provided in the vehicle interior (specifically, the instrument panel) of the vehicle 10. (Corresponding to the “operation unit”). For example, the leveling dial 37 can change the irradiation direction steplessly in a range of “0” to “3”. When the leveling dial 37 is set to “0”, the irradiation direction is most upward and is set to “3”. The irradiation direction is the most downward.

  Here, the weight distribution in the front-rear direction of the vehicle 10 is in an average boarding state (for example, a state in which people and luggage are mounted only in the driver's seat or only in the driver's seat and the passenger seat, see FIG. 4A). In the case of weight distribution, the leveling dial 37 is normally set to “0”. That is, the irradiation direction of the headlamp 60 is set most upward with respect to the vehicle body 10A. Further, when the weight distribution at the rear portion of the vehicle 10 increases, the driver sets the leveling dial 37 to any value larger than “0” accordingly. Then, the reflector 61 provided in the headlamp 60 is tilted downward by the motor 62, and the irradiation direction of the headlamp 60 is tilted downward with respect to the vehicle body 10A (see FIG. 4B). As the set value R1 of the leveling dial 37 (hereinafter, referred to as “dial set value R1” as appropriate) increases, the amount of tilt in the irradiation direction with respect to the vehicle body 10A increases downward.

  As shown in FIG. 1, among the sensors 25 and 34 to 36 described above, the detection values T1, V, and θ2 by the sensors 34 to 36 other than the rotational position sensor 25 and the set value R1 of the leveling dial 37 are as follows. The assist current command value I1 is calculated here. The motor drive circuit 42 applies a drive current according to the assist current command value I1 to the steered motor 19, and the steered motor 19 generates an assist force according to the drive current. Then, the front wheels 50 are steered by the resultant force of the assisting force by the steering motor 19 and the steering force of the steering wheel 33 by the driver. The rotational position of the rotor 21 detected by the rotational position sensor 25 is acquired by the motor drive circuit 42. The drive current applied to the steered motor 19 is feedback controlled based on the rotational position of the rotor 21. The steering control device 41 corresponds to the “inclination amount detecting means” according to the present invention.

  The steering control device 41 executes, for example, the motor current command value calculation program PG1 shown in FIG. 2 at a predetermined cycle (for example, 4.0 [msec] cycle). Specifically, when the motor current command value calculation program PG1 is executed, the steering control device 41 detects the detection results (the steering angle θ2, the steering torque T1, the steering torque T1, the steering torque sensor 35, the vehicle speed sensor 36). In addition to acquiring the vehicle speed V), the dial setting value R1 is acquired as a substitute value for the amount of inclination of the irradiation direction of the headlamp 60 (S1).

  Next, the steering control device 41, based on the torque / vehicle speed-current command value map mp1 (see FIG. 3), determines the basic current command value I11 corresponding to the steering torque T1 and the vehicle speed V (the target value of assist force in the present invention). (S2). Next, a compensation current command value I12 is determined based on the steering angle θ2, the steering torque T1, and the vehicle speed V (S3).

  Next, based on the dial set value / load conversion map mp21 (see FIG. 3), the dial set value R1 is converted into an estimated value F of the load applied to the front wheels 50, 50 (hereinafter referred to as “estimated load F”). Based on the load-gain map mp22 (see FIG. 3), an assist gain G1 corresponding to the estimated load F is determined (S4). The dial set value / load conversion map mp21 and the load-gain map mp22 correspond to the “assist gain corresponding map” of the present invention.

  Next, the assist current command value I1 (= G1 · (I11 + I12)) is calculated by multiplying the value obtained by adding the compensation current command value I12 to the basic current command value I11 and the assist gain G1 (S5). The assist current command value I1 corresponds to the “target value of assist force corrected by the target value correcting means” according to the present invention.

  Then, the assist current command value I1 is output to the motor drive circuit 42 (S6). As a result, an assist force corresponding to the assist current command value I1 is generated. When the assist current command value I1 is output, the motor current command value calculation program PG1 ends and is re-executed after a predetermined period.

  Here, the control system shown in the block diagram of FIG. 3 is configured by executing the motor current command value calculation program PG1. In the figure, a basic current command value calculation unit 43 is configured by step S2, a compensation current command value calculation unit 44 is configured by step S3, and a gain calculation unit 45 is configured by step S4. The value calculation unit 46 is configured by step S5. The basic current command value calculation unit 43 (step S2) and the torque / vehicle speed-current command value map mp1 correspond to the “assist force determination means” of the present invention, and the gain calculation unit 45 (step S4) and the assist current. The command value calculation unit 46 (step S5) corresponds to “target value correction means” of the present invention. This completes the description of the motor current command value calculation program PG1.

  By the way, the dial set value / load conversion map mp21 shown in FIG. 3 is set as follows. That is, from the weight distribution in the average boarding state (for example, see FIG. 4A), when a person or luggage is placed on the rear seat or the luggage is placed on the trunk room at the rear of the vehicle 10, When the weight distribution is increased, the vehicle body 10A is tilted backward, the front portion of the vehicle body 10A is lifted, and the irradiation direction of the headlamp 60 is shifted upward. Then, in order to correct this deviation, the driver sets the leveling dial 37 to a value larger than “0”, and the irradiation direction of the headlamp 60 is tilted downward according to the dial setting value R1. Normally, the leveling dial 37 becomes larger as the upward displacement in the irradiation direction of the headlamp 60 increases (in other words, the lift of the front portion of the vehicle body 10A increases), in other words, as the load applied to the front wheels 50, 50 decreases. Set to a large value. Accordingly, in the dial set value / load conversion map mp21, when the dial set value R1 is “0”, the estimated load F becomes maximum, and as the dial set value R1 increases, the estimated load F gradually decreases. The estimated load F is set to be minimum when R1 is “3”.

  The load-gain map mp22 fixes the assist gain G1 to “1” when the estimated load F is maximum (when the dial setting value R1 is “0”), and the estimated load F becomes smaller (dial setting). The assist gain G1 is set to gradually decrease from “1” as the value R1 increases.

  By setting the dial set value / load conversion map mp21 and the load-gain map mp22 as described above, for example, the rear seat and the trunk room of the vehicle 10 are packed with people and luggage, and the actual loads applied to the front wheels 50 and 50 are compared. When the target is small, the assist force output from the steering motor 19 is small. On the contrary, for example, when there is no person or luggage other than the driver and the actual load applied to the front wheels 50 and 50 is relatively large, the assist force output from the steered motor 19 is increased. Therefore, the driver can operate the steering wheel with a substantially constant steering force regardless of the load applied to the front wheels 50, in other words, the change in weight distribution in the front-rear direction of the vehicle 10.

  As shown in FIG. 3, the vehicle speed / torque-current command value map mp1 is set so that the basic current command value I11 increases as the steering torque T1 increases, and in the case of the same steering torque T1. The basic current command value I11 is set to decrease as the vehicle speed V increases. That is, the assist force of the steering motor 19 increases as the steering torque T1 during steering of the steering wheel increases, while the assist force of the steering motor 19 decreases as the vehicle speed V increases. As a result, the steering wheel can be steered with a light steering force at low speeds, while the steering wheel 33 becomes heavy at high speeds to prevent wobbling.

  Next, the operation of the present embodiment configured as described above will be described. For example, when the driver steers the steering wheel 33, the basic current command value I11 is calculated based on the steering torque T1 and the vehicle speed V applied to the steering shaft 32, and the compensation current is calculated based on the steering torque T1, the vehicle speed V, and the steering angle θ2. The command value I12 is calculated.

  Here, when there is no person or baggage other than the driver (in the case of an average boarding state), the driver normally sets the leveling dial 37 to “0”. Since the estimated load F obtained from the dial setting value / load conversion map mp21 based on the dial setting value R1 is maximized, the assist gain G1 is set to “1”. The assist current command value I1 (= G1 · (I11 + I12)) is calculated from the assist gain G1, the basic current command value I11, and the compensation current command value I12, and is output to the motor drive circuit 42. Then, the motor is driven. The circuit 42 applies a driving current corresponding to the assist current command value I1 to the steering motor 19, and the steering motor 19 outputs an assisting force corresponding to the driving current to steer the front wheels 50 and 50. As a result, the driver can operate the steering wheel while feeling a stable steering reaction force regardless of the steering torque T1.

  On the other hand, when the weight distribution at the rear part of the vehicle 10 increases, specifically, for example, when a person or luggage is placed on the rear seat of the vehicle 10 and the trunk room is empty, the front part of the vehicle body 10A is slightly lifted and the head The irradiation direction of the lamp 60 is slightly shifted upward. Then, in order to correct this deviation, the driver usually sets the leveling dial 37 to “1” to “2”. At this time, the assist gain G1 obtained from the dial set value / load conversion map mp21 and the load-gain map mp22 based on the dial set value R1 is a value smaller than “1” (for example, “0.8” to “0.9”). )), And the assist current command value I1 is reduced by the assist gain G1. That is, the assist force output from the steering motor 19 is smaller than when the driver is riding alone.

  Further, for example, as shown in FIG. 4B, when the rear seat of the vehicle 10 is full and the trunk room is full of luggage, the front part of the vehicle body 10A is lifted relatively large, and the irradiation direction of the headlamp 60 is changed. It shifts greatly upwards. Then, in order to correct this deviation, the driver usually sets the leveling dial 37 to the maximum “3”. At this time, since the estimated load F obtained from the dial setting value / load conversion map mp21 based on the dial setting value R1 is minimum, the assist gain G1 is a minimum value smaller than “1” (for example, “0.7”). The assist current command value I1 is reduced by the assist gain G1. That is, the assist force output from the steered motor 19 is even smaller than when a person or luggage is placed on the rear seat and the trunk room is empty.

  In this way, when the weight distribution at the rear of the vehicle 10 increases, the steered motor 19 is more than in the weight distribution in the average riding state (when the estimated load F applied to the front wheels 50, 50 is maximum). A small assist force is output and the front wheels 50 and 50 are steered. As a result, it is possible to prevent the sudden handle or the wobbling of the handle 33 due to an excessive assist force.

  Specifically, when the weight distribution in the front-rear direction of the vehicle 10 changes, the frictional resistance between the front wheels 50, 50 and the road surface also increases and decreases, and the force required for turning the front wheels 50, 50 (that is, the steering force and the assist force) is increased. The combined force is also increased or decreased. In the conventional apparatus, the excess or deficiency of the assist force due to the increase or decrease of the frictional resistance can be dealt with only by feedback control using a steering torque sensor. On the other hand, in the electric power steering apparatus 11 of the present embodiment, the increase / decrease of the frictional resistance (change in weight distribution in the front-rear direction of the vehicle 10) is tilted up and down with respect to the vehicle body 10A. Is detected as the set value R1 of the leveling dial 37, and so-called feedforward control is performed to correct (increase / decrease) the assist current command value I1 in accordance with the dial set value R1. From time to time, an optimal assist force according to the weight distribution in the front-rear direction of the vehicle 10 (in other words, the load applied to the front wheels 50, 50) is output, and a good steering feeling can be provided.

  As described above, according to the electric power steering apparatus 11 of the present embodiment, the set value R1 of the leveling dial 37 is detected as a substitute value of the tilt amount with respect to the vehicle body 10A in the irradiation direction of the headlamp 60, and based on the dial set value R1. The assist current command value I1 is corrected (increased / decreased) by the assist gain G1 thus determined. Thereby, even if there is a change in weight distribution in the front-rear direction of the vehicle 10 (increase / decrease in load applied to the front wheels 50, 50), the assist force is increased / decreased accordingly, so that the influence on the steering feeling is suppressed. That is, good steering feeling can be provided regardless of the change in the weight distribution in the longitudinal direction of the vehicle 10.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

  (1) In the above embodiment, the basic current command value I11 and the assist gain G1 are determined from the maps mp1, mp21, and mp22 according to the detection values T1, V, and θ2 of the sensors 34 to 36 and the dial setting value R1. However, it may be determined by an arithmetic expression.

  (2) The electric power steering device 11 is not limited to the so-called rack coaxial type exemplified in the above embodiment, and may be a column type or a pinion type.

  (3) In the above embodiment, two maps, the dial set value / load conversion map mp21 and the load-gain map mp22, are provided, but the assist gain G1 can be directly obtained from the set value R1 of the leveling dial 37. A dial set value-gain map may be provided.

  (4) The leveling dial 37 has a configuration in which the irradiation direction of the headlamp 60 can be set steplessly, but stepwise (for example, four steps of “0”, “1”, “2”, “3”). A configuration that can be set is also possible. In this case, the estimated load F and the assist gain G1 in the dial set value / load conversion map mp21 and the load-gain map mp22 may be set so as to change stepwise according to the dial set value R1.

  (5) As shown in FIG. 5, the rotational position of the motor 62 that tilts the reflector 61 of the headlamp 60 is detected by the rotational position sensor 63, and the detected rotational position of the motor 62 is detected in the irradiation direction of the headlamp 60. As an alternative value of the amount of inclination with respect to the vehicle body 10A, the assist force may be increased or decreased according to this rotational position. Specifically, the rotational position of the motor 62 detected by the rotational position sensor 63 is converted into an estimated load F applied to the front wheels 50 and 50 by the motor rotational position / load conversion map mp21 ′. The process may be performed in the same manner as. In this case, the rotational position sensor 63 corresponds to the “inclination amount detecting means” of the present invention.

  (6) In the above-described embodiment, the present invention is applied to the electric power steering apparatus 11 of the vehicle 10 in which the irradiation direction of the headlamp 60 can be manually adjusted. However, the irradiation direction of the headlamp 60 depends on the inclination of the vehicle body 10A. The present invention may be applied to an electric power steering device for a vehicle equipped with an auto levelizer that automatically adjusts. In this case, the rotational position of the motor 62 that tilts the reflector 61 may be detected by the rotational position sensor 63 as a substitute value for the amount of tilt in the irradiation direction of the headlamp 60 (see FIG. 5).

The conceptual diagram of the vehicle which concerns on one Embodiment of this invention. Motor current command value calculation program flowchart Steering control device block diagram (A) Conceptual diagram of the vehicle in an average riding state, (B) Conceptual diagram of the vehicle in a state where the weight distribution at the rear of the vehicle is increased Block diagram of a steering control device according to another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle 10A Car body 11 Electric power steering apparatus 33 Handle 37 Leveling dial (operation part)
41 Steering control device (inclination amount detecting means)
43 Basic current command value calculation unit (assist force determination means)
45 Gain calculation section (target value correction means)
46 Current command value calculation unit for assist (target value correction means)
50 Front wheels (steering wheels)
60 Headlamp (headlight)
61 Reflector 62 Motor 63 Position sensor (Tilt detection means)
G1 assist gain I1 assist current command value I11 basic current command value I12 compensation current command value T1 steering torque V vehicle speed mp1 current command value map (assist force determining means)
mp21 Fuel amount / load conversion map (assist gain map)
mp22 Load-gain map (assist gain map)

Claims (4)

Electric power that is provided in a vehicle capable of tilting the headlight irradiation direction up and down with respect to the vehicle body according to the vehicle body front-rear tilt, and outputs an assist force for assisting steering of the steering wheel In the steering device,
Assist force determining means for determining a target value of the assist force according to a vehicle speed and a steering torque for steering the steering wheel;
A tilt amount detecting means for detecting a tilt amount of the irradiation direction of the headlamp with respect to the vehicle body;
Target value correcting means for correcting so that the target value of the assist force decreases as the amount of inclination of the irradiation direction detected by the inclination amount detecting means increases downward with respect to the vehicle body,
An electric power steering apparatus that outputs the assist force according to a target value of the assist force corrected by the target value correcting means. The vehicle is provided with an operation unit capable of manually setting a tilt amount of the irradiation direction with respect to the vehicle body,
The electric power steering apparatus according to claim 1, wherein the tilt amount detection unit detects a set value by the operation unit as a substitute value of the tilt amount in the irradiation direction. The headlamp includes a reflector that reflects light from a light source forward and can be tilted vertically with respect to the vehicle body.
2. The electric power steering apparatus according to claim 1, wherein the tilt amount detection unit detects a rotation position of a motor that tilts the reflector with respect to the vehicle body as a substitute value of the tilt amount in the irradiation direction. The target value correcting means has an assist gain correspondence map in which the amount of inclination in the irradiation direction is associated with an assist gain,
Based on the assist gain correspondence map, the assist gain is determined from the tilt amount in the irradiation direction detected by the tilt amount detecting means, and the determined assist gain is multiplied by the assist force target value for correction. The electric power steering apparatus according to claim 1, wherein the electric power steering apparatus is performed.

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