JP2008174066A - Vehicle steering device - Google Patents

Abstract

An object of the present invention is to provide a vehicle steering apparatus capable of suppressing an increase in the number of specifications even when the number of actuator types and vehicle types increases.
An actuator 10 is provided on each of the left and right wheels and includes a reduction mechanism that can extend and contract in the axial direction, a control means 30 that instructs an operation amount of the actuator 10, and a drive means 20 that drives the actuator. The vehicle steering apparatus 1 in which the toe angles of the left and right wheels can be independently changed by the actuator 10, the control means 30, and the drive means 20, wherein the drive means 20 is based on the position information of the actuator 10. The drive means 20 is configured integrally with the actuator 10 and is arranged separately from the control means 30.
[Selection] Figure 3

Description

  The present invention relates to a vehicle steering apparatus capable of independently toe-controlling the left and right rear wheels of a four-wheeled vehicle, for example.

  Conventionally, various four-wheel steering devices for controlling the toe angle of the rear wheels have been proposed for the purpose of improving the turning performance of the vehicle. For example, when traveling at low speeds, the toe angle of the front and rear wheels can be reversed to reduce the minimum turning radius, and at high speeds, the toe angle of the front and rear wheels can be set to the same phase when cornering or changing lanes. The maneuverability at the time of can be improved. As a technique for independently controlling the toe angles of the left and right rear wheels, a technique using an actuator by a hydraulic mechanism has been proposed (see, for example, Patent Document 1). In addition, an actuator using a feed screw mechanism instead of a hydraulic mechanism has been proposed (see, for example, Patent Document 2).

As shown in FIG. 5, in the conventional steering apparatus 100, an ECU ASSY (ECU assembly part) 105 in which an actuator 102 having a stroke sensor 101, an ECU (Electronic Control Unit) 103, and a driver 104 are integrally formed. Are connected by a harness 106. Further, ECU 103 transmits a drive signal (motor rotation direction, DUTY) to driver 104 based on position information received from stroke sensor 101.
Japanese Examined Patent Publication No. 6-98937 (Fig. 2) Japanese Examined Patent Publication No. 6-47388 (Fig. 4)

  However, when the ECU ASSY 105 in which the ECU 103 and the driver 104 are combined as in the prior art, there is a problem that the specification increases as the type of the actuator 102 and the vehicle type increase.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a vehicle steering apparatus that can suppress an increase in the number of specifications even when the types of actuators and vehicle types increase.

  The present invention includes an actuator provided on each of the left and right wheels and provided with a reduction mechanism capable of extending and contracting in the axial direction, a control means for instructing an operation amount of the actuator, and a drive means for driving the actuator, The vehicle steering apparatus in which the toe angles of the left and right wheels can be independently changed by the actuator, the control means, and the drive means, wherein the drive means calculates a target current based on position information of the actuator, The drive means is configured integrally with the actuator and is arranged separately from the control means.

  According to this, position information from the actuator can be returned not to the control means but to the control means configured integrally with the actuator, so that the signal sent from the control means to the drive means can be minimized, and control is performed. It is possible to suppress an increase in the number of specifications of the means (for example, ECU).

  Further, the left and right actuators may be controlled by one control means. According to this, the number of parts can be reduced and the manufacturing cost can be suppressed as compared with the case where the control means are provided independently for the left and right actuators.

  ADVANTAGE OF THE INVENTION According to this invention, even if the kind of actuator and a vehicle type increase, the steering apparatus of the vehicle which can suppress the increase in a specification number can be provided.

  FIG. 1 is a plan view showing a vehicle steering apparatus according to the present embodiment, FIG. 2 is a schematic sectional view showing the structure of an actuator according to the present embodiment, and FIG. 3 is a block diagram showing the vehicle steering apparatus according to the present embodiment. 4 is a simplified block diagram showing the vehicle steering apparatus of the present embodiment.

  As shown in FIG. 1, a vehicle steering apparatus 1 according to this embodiment is attached to left and right rear wheels (left and right wheels) 2 of a vehicle (for example, a four-wheel automobile), and includes an actuator 10 and a drive device ( Drive means) 20 and ECU (control means) 30. FIG. 1 shows only the left rear wheel 2, but the right rear wheel is also attached in a similar manner (symmetric). Hereinafter, a trailing arm type suspension will be described as an example.

  One end (rear end) of a trailing arm 3 extending substantially in the longitudinal direction of the vehicle body is fixed to the rear wheel 2, and the other end (front end) of the trailing arm 3 is supported by a cross member 4 extending substantially in the vehicle width direction. ing. The end of the cross member 4 is elastically supported by the rear side frame 5. The trailing arm 3 has a vehicle body side arm 3a pivotally attached to the cross member 4 (vehicle body) via a bush (not shown), a rear wheel 2 and a rear end of the vehicle body side arm 3a. The wheel side arm 3b to be inserted is configured to be connected via a substantially vertical rotation shaft and a bush (both not shown). As a result, relative rotation between the vehicle body side arm 3a and the wheel side arm 3b can be performed about the rotation axis in the substantially vertical direction, and displacement of the trailing arm 3 in the vehicle width direction is allowed. It is configured as follows.

  One end of the actuator 10 is attached to the trailing arm 3 (wheel side arm 3b), and the other end is attached to the cross member 4.

As shown in FIG. 2, the actuator 10 includes a feed screw portion 11, a speed reduction mechanism 12, an electric motor 13, and the like.
The feed screw portion 11 is movable in the axial direction by engaging the rod 11a formed in a cylindrical shape, a nut 11c in which a screw groove 11b is formed and inserted into the rod 11a, and the screw groove 11b. And a screw shaft 11d to be supported by the screw shaft. The screw shaft 11d is housed in an elongated case body 14 together with the speed reduction mechanism 12 and the electric motor 13, one end of the speed reduction mechanism 12 is connected to the output shaft of the electric motor 13, and the other end is connected to the screw shaft 11d.
The speed reduction mechanism 12 is configured by combining, for example, a two-stage planetary gear (not shown).
The electric motor 13 includes a brush motor or a brushless motor that can rotate in both forward and reverse directions. The power from the electric motor 13 is transmitted to the screw shaft 11d via the speed reduction mechanism 12 and the screw shaft 11d rotates, so that the rod 11a operates to extend and contract in the horizontal direction (axial direction) in the figure with respect to the case body 14. It is supposed to be. Further, a boot 15 is attached to the actuator 10 so that foreign matter such as dust and water from the outside does not enter.

  The actuator 10 is provided with a stroke sensor 18 that detects the position (expansion / contraction amount) of the rod 11a. The stroke sensor 18 includes, for example, a magnet and can detect a position using magnetism. Thus, by detecting the position using the stroke sensor 18, the toe-in and toe-out toe angles of the rear wheel 2 can be detected with high accuracy.

  In the actuator 10 configured in this manner, the connecting portion 16 provided at the distal end of the rod 11a is rotatably connected to the wheel side arm 3b (see FIG. 1) of the trailing arm 3, and the base end of the case body 14 is connected. Is connected to the cross member 4 (see FIG. 1) via a ball joint (not shown) or the like. When the screw shaft 11d is rotated by the power of the electric motor 13 and the rod 11a extends (left direction in FIG. 2), the trailing arm 3 is pressed outward in the vehicle width direction (left direction in FIG. 1), and the rear wheel 2 is moved. When the rod 11a is turned leftward and the rod 11a is contracted (rightward in FIG. 2), the trailing arm 3 is pulled inward in the vehicle width direction (rightward in FIG. 1), and the rear wheel 2 turns rightward. .

  The actuator 10 is integrally configured with a drive device 20. In other words, the drive device 20 is configured to be fixed to the case main body 14 of the actuator 10 and connected to the stroke sensor 18 via a connector or the like.

  As shown in FIG. 3, the drive device 20 has a function of driving the actuator 10, and includes an actuator controller (hereinafter abbreviated as ACT controller) 21 and a driver 22. The driving device 20 is connected to an ECU (Electronic Control Unit) 30 via an electric wire 40.

  The ECU 30 has a function of instructing the operation amount of the actuator 10, and is connected to the driving device 20 provided in the actuator 10 via the electric wire 40. The electric wire 40 here does not include a power line for supplying electric power from the ECU 30 to the driving device 20.

  The ACT control unit 21 includes a CPU (Central Processing Unit) and the like, and includes a target current calculation unit (target current calculation unit) 21a, a correction current setting unit 21b, and the like. The target current calculation unit 21 a calculates a target current signal (target current) based on a signal input from the ECU 30 and outputs the target current signal to the driver 22. The target current signal is a current signal necessary for setting the actuator 10 to a desired operation amount (a telescopic amount that makes the rear wheel 2 a desired toe angle). The correction current setting unit 21b outputs a correction current signal for correcting the target current signal based on the position information input from the stroke sensor 18 to the target current calculation unit 21a. Further, the target current calculation unit 21 a adds or subtracts the correction current signal to the target current signal, and outputs the corrected target current signal to the driver 22. The configuration of the ACT control unit 21 described above is an example, and the correction current setting unit 21b is included in the target current calculation unit 21a, and the processing of the correction current setting unit 21b is performed in the target current calculation unit 21a. Also good.

  The driver 22 includes a motor control signal generator 22a, a motor drive circuit 22b, and the like. The motor control signal generation unit 22a receives the target current signal from the ACT control unit 21 and outputs the motor control signal to the motor drive circuit 22b. This electric motor control signal is a signal including the current value supplied to the electric motor 13 and the direction in which the electric current flows. The motor drive circuit 22b is configured by a FET (Field Effect Transistor) bridge circuit or the like, and applies a motor voltage to the motor 13 based on a motor control signal.

  The ECU 30 includes a CPU and the like, and is housed in a box (not shown) or the like provided in another place (for example, near the trunk room) away from the actuator 10. Further, the ECU 30 outputs a signal for setting the actuator 10 to a desired operation amount (a telescopic amount for setting the toe angle of the rear wheel 2 to a desired angle) to the ACT control unit 21 of the drive device 20. Further, the ECU 30 is connected to the steering angle sensor 31 and the vehicle behavior sensor 32, the steering angle of the steering wheel (not shown) is detected by the steering angle sensor 31, and the vehicle behavior sensor 32 (vehicle speed sensor, yaw rate sensor) The vehicle speed, the speed at which the vehicle rotates (spins), and the like are detected. Based on detection values obtained from the steering angle sensor 31 and the vehicle behavior sensor 32, the toe angles of the left and right rear wheels 2 can be independently controlled at a desired angle.

  As shown in FIG. 4, in the vehicle steering apparatus 1 according to the present embodiment, the ECU 30 sends signals from the drive device 20 (ACT control unit 21) to the state of the electric motor 13 and the state of the driver 22, that is, the electric motor 13 and the driver 22. Is receiving and monitoring whether or not it is operating soundly. Further, the drive device 20 (ACT control unit 21) monitors the current and voltage applied to the electric motor 13 via the electric wire 50. The drive device 20 is supplied with electric power from a power source such as a battery mounted on the vehicle (see FIG. 4). The ECU 30 is also supplied with electric power from a power source such as a battery (not shown) in a separate system from the above. In the present embodiment, not only the left rear wheel 2 but also the right rear wheel, similarly, the actuator 10B in which the driving device 20 is integrally configured is configured, and the driving device 20 includes the actuator 10 (10A). Are connected to the common ECU 30. Therefore, the ECU 30 according to the present embodiment can independently output signals for controlling the operation amounts of the actuators 10A and 10B to the drivers 22 of the left and right actuators 10A and 10B.

  In the vehicle steering apparatus 1 configured as described above, the ECU 30 outputs a command for setting the actuator 10 to a desired operation amount to the ACT control unit 21, so that the ACT control unit 21 becomes the target. The target current signal to be calculated is calculated, and this target current signal is output to the driver 22. The driver 22 generates a drive signal for driving the motor 13 at a predetermined rotational speed in the forward direction or the reverse direction based on the received target current signal, and outputs the drive signal to the motor 13. As a result, the rod 11a of the actuator 10 expands and contracts by moving the trailing arm 3 outward or inward in the vehicle width direction, and the rear wheel 2 turns left or right. The actual position information of the actuator 10 detected by the stroke sensor 18 is output to the ACT control unit 21 via the electric wire 45. In the ACT control unit 21, the correction current signal is added to or subtracted from the target current signal, and the corrected target current signal is sent to the motor 13 via the driver 22, thereby correcting the position of the motor 13. As a specific example in which the left and right rear wheels 2 are independently controlled, it is possible to improve turning performance by toe-controlling only the outer wheel side when the vehicle is turning.

  By the way, many types of actuators 10 in which the pitch of the feed screw is changed depending on the vehicle type are required. However, as in this embodiment, the driving device 20 calculates the target current and the driving means is integrated with the actuator 10. By configuring and separately arranging from the ECU 30, position detection and current control feedback processing (hereinafter referred to as F / B) within the actuator 10 without returning the detection value (position information) from the stroke sensor 18 to the ECU 30. Abbreviated processing). Therefore, since the F / B loop is formed only on the actuator 10 side, it can be set according to the variation of each actuator 10 (it is not necessary to set according to the ECU 30), and the processing speed can be increased. It becomes possible. That is, since the ECU 30 only has to give an instruction as to how much the actuator 10 wants to move, the load on the ECU 30 can be minimized. This also facilitates replacement of the ECU 30.

  Further, when there are three types of actuators and three types of vehicles (vehicle types), the conventional example shown in FIG. 5 requires an ECU (control means + drive means) individually, so the number of specifications is 3 types × 3 types. = 9 types are required. Note that the different types of actuators include different feed screw pitches and different motor sizes. In contrast, in the present embodiment, when a drive device (drive means) 20 produced for the number (type) of actuators 10 and an ECU (control means) 30 produced for a vehicle (vehicle type) are prepared. The required number of specifications is 3 types + 3 types = 6 types, and these 6 types can cover all specifications. That is, in the conventional configuration, if the vehicle (vehicle type) changes, it is necessary to change the specification (ECUASSY 105) according to each actuator. In the present embodiment, even if the vehicle (vehicle type) changes. There is no need to change the specifications (ECU 30) according to each actuator. As described above, the number of specifications obtained by the present embodiment may be only the number obtained by adding the type of the drive device 20 and the type of the ECU 30. Therefore, the effect of reducing the number of specifications becomes more prominent as the number of actuators 10 and vehicle types increase. Become. Therefore, it can be applied to many types of actuators 10 and many types of vehicles without increasing the number of specifications.

  Also, as in the conventional example (FIG. 5), when the electric motor of the actuator 102 and the ECU 103 are connected, the F / B (feedback) loop becomes very long, and the phase delay increases due to the length of the F / B loop. There is a problem that the control accuracy is lowered. On the other hand, in this embodiment, since the drive device 20 itself can calculate the target current, the F / B loop can be made the shortest, and the control accuracy can be improved.

  In the conventional example, a long power supply harness 106 for supplying power from the ECU ASSY 104 to the actuator 102 is required. However, in this embodiment, a power supply harness for supplying power from the ECU 30 to the actuator 10 can be almost unnecessary. The effect is obtained.

  In the present embodiment, the actuator 10 (10A, 10B) in which the left and right drive devices 20 are integrated is controlled by the common ECU 30, thereby reducing the number of parts and reducing the cost.

  In the above-described embodiment, the example applied to the trailing arm type suspension has been described. However, the present invention is not limited to this, and the present invention is applied to a double wishbone type suspension, a multilink type suspension, and the like. May be. Further, in the case of the double wishbone type or the multi-link type, the place where the actuator 10 is attached may be a position where the toe angle of the rear wheel 2 can be changed, such as a knuckle.

It is a top view which shows the steering device of the vehicle of this embodiment. It is a schematic sectional drawing which shows the structure of the actuator of this embodiment. 1 is a block diagram illustrating a vehicle steering apparatus according to an embodiment. 1 is a simplified block diagram illustrating a vehicle steering apparatus according to an embodiment. It is a block diagram which shows the steering device of the conventional vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle steering device 2 Rear wheel 10 Actuator 12 Deceleration mechanism 20 Drive device (drive means)
30 ECU (control means)

Claims (2)

An actuator provided on each of the left and right wheels and provided with a speed reduction mechanism capable of expanding and contracting in the axial direction;
Control means for instructing the operating amount of the actuator;
Driving means for driving the actuator,
A vehicle steering apparatus in which the toe angles of the left and right wheels can be independently changed by the actuator, the control means, and the drive means,
The drive means calculates a target current based on position information of the actuator,
The vehicle steering apparatus according to claim 1, wherein the driving unit is configured integrally with the actuator and is disposed separately from the control unit.   The vehicle steering apparatus according to claim 1, wherein the left and right actuators are controlled by a single control means.

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