JP2009149184A - Electric power steering and electric damper system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering and an electric damper system capable of easily combining the operation feeling of a steering wheel and riding comfortability by a suspension device without causing conflict. <P>SOLUTION: In the electric motor 4 for power steering, the electric power steering device 301 having a torque sensor 17 for controlling the drive of the electric motor 4 and outputting a steering auxiliary force, and the electric damper device 303 (in Fig.8, indicated as 303FL, 303FR, 303RL and 303RR) for converting the vertical motion of a wheel to the rotation of the electric motor 35 (in Fig.8, indicated as 35FL, 35FR, 35RL and 35RR) for the damper and controlling an attenuation force by the electric motor 35, the control of the electric motor 4 and the electric motor 35 is performed on a CPU of a micro-computer included in one ECU 200. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering device including an electric power steering device for applying a steering assist force by an electric motor for power steering to a steering system of an automobile or a vehicle, and an electric damper device provided in a vehicle suspension device. -Regarding the system.

In general, an electric power steering apparatus that reduces a steering force applied to a steering handle of a driver by a steering assist force of an electric motor is generally well known (see Patent Document 1). Also, in recent years, instead of hydraulic dampers used in suspension devices, a rack and pinion mechanism is used to convert to rotational motion by a pinion gear meshed with a rod that moves up and down as the wheels move up and down. There has been proposed an electric damper that transmits a rotational motion to an electric motor for a damper and controls a damping force of the damper by controlling regenerative power generation of the electric motor (see Patent Document 2).
JP 2007-276571 A JP 2005-256922 A

However, the conventional electric power steering device and the electric damper device control and calculate the electric motor for power steering and the electric motor for damper by individual microcomputers, and individually control each electric motor. The control device was individually mounted on the vehicle. Therefore, for example, analog data such as steering torque input to the microcomputer of the electric power steering device and vertical displacement of the wheel input to the microcomputer of the electric damper device is converted into digital data that can be combined with each microcomputer. When converted to digital data in the AD converter to be converted, depending on variations in the characteristics of the AD converter, an electric power steering device with a light steering force and an electric damper device with a high damping force, that is, a hard riding comfort can be combined. There is a possibility that it will be, and the reverse combination.
In general, a vehicle with a light steering handle feel is a luxury vehicle, and a vehicle with a soft riding comfort by a suspension device is preferred.
Conversely, a car with a heavy steering handle feel is a sporty car, and it is preferred that the suspension device has a hard ride. This is because the driver can drive with emphasis on the controllability of the vehicle.
If the combination of these characteristics is reversed, for example, if the steering wheel has a light operating feeling, but the riding comfort of the suspension device is hard, driving is difficult due to driving characteristics, and passenger comfort is lost.
In order to solve the above problems, an object of the present invention is to provide an electric power steering / electric damper system that can easily combine the operation feeling of the steering wheel and the riding comfort of the suspension device without any contradiction.

In order to solve the above-mentioned problems, an invention according to claim 1 is directed to a power steering based on an electric motor for power steering, a steering torque sensor for detecting a steering torque from a steering handle, and at least a signal from the steering torque sensor. An electric power steering control means for controlling the driving of the electric motor for steering, and a steering motor driving means for driving the electric motor for power steering based on a signal from the electric power steering control means. An electric power steering device that outputs auxiliary torque for steering;
A conversion mechanism for converting the vertical movement of the wheel into the rotation of the electric motor for the damper, a position detection means for detecting the position of the vertical movement of the wheel, and attenuation by the electric motor for the damper based on at least a signal from the position detection means Electric damper control means for controlling the force, and damper motor driving means for generating a damping force by the electric motor for the damper based on a signal from the electric damper control means, and the vertical movement of the wheel is attenuated by the conversion mechanism An electric damper device,
The electric power steering control means and the electric damper control means are executed on at least one same microcomputer.

  In particular, in the microcomputer, at least on the route until a signal is sent to a CPU (Central Pricessing Unit), the signal from the steering torque sensor and the signal from the position detection means are input to the same AD converter via the interface circuit. Therefore, it is desirable to convert from an analog signal to a digital signal.

  The electric power steering control means and the electric damper control means are executed on one microcomputer, in particular, input to the same AD converter by the interface circuit, and input to the CPU of one common microcomputer for arithmetic control. It is possible to prevent the combination of the variation in the auxiliary torque characteristic of the electric power steering device due to the variation in the characteristic of the circuit included in the AD converter or the input interface circuit and the variation in the attenuation characteristic of the electric damper from occurring independently.

  According to the present invention, it is possible to provide an electric power steering / electric damper / system that can easily combine the operation feeling of the steering wheel and the riding comfort of the suspension device without contradiction.

Embodiments of the present invention will be described with reference to the drawings.
<Main components of electric steering, electric damper and system>
First, with reference to FIG. 1 and FIG. 2 and FIG. 4 as appropriate, main components of the electric steering / electric damper system according to the embodiment will be described.
FIG. 1 is a layout diagram of main components of an electric steering / electric damper system according to an embodiment of the present invention.
As shown in FIG. 1, a pinion gear 7a meshes with a rack gear 8a that steers left and right front wheels (wheels) 1FL, 1FR, and a handle shaft of the steering handle 3 is connected to a rack shaft 8 of the rack gear 8a. Connected through. A driving force is transmitted between the steering handle 3 and the pinion gear 7a from a torque sensor (steering torque sensor) 17 and an electric motor 4 for power steering that applies a steering assist force (auxiliary torque) to the pinion shaft 7. A worm wheel gear 5b is provided to constitute an electric power steering mechanism 25 that is a mechanical component of the electric power steering device.
Here, the wheels 1FL and 1FR correspond to the steered wheels recited in the claims.
An output signal from the torque sensor 17 is input to a control ECU (Electric Control Unit) 200. The electric motor 4 is controlled by the control ECU 200 by signals from the vehicle speed sensor 104, the torque sensor 17 (see FIG. 2), and the like.
The detailed configuration of the electric power steering mechanism 25 will be described later with reference to FIG.

Further, electric damper conversion mechanisms (conversion mechanisms) 30FL, 30FR, 30RL, and 30RR are incorporated in suspension devices 14FL, 14FR, 14RL, and 14RR (see FIG. 4) provided in the respective wheels 1FL, 1FR, 1RL, and 1RR. Each of the electric damper conversion mechanisms 30FL, 30FR, 30RL, 30RR has damper electric motors 35FL, 35FR, 35RL, 35RR controlled by the control ECU 200, respectively. Further, the suspension devices 14FL, 14FR, 14RL, 14RR (see FIG. 4) include displacement amount detection sensors (position detection means) 80FL, 80FR, 80RL, which detect the vertical displacement amounts of the wheels 1FL, 1FR, 1RL, 1RR. 80RR is provided, and an output signal thereof is input to the control ECU 200.
The detailed configuration of the electric damper conversion mechanisms 30FL, 30FR, 30RL, and 30RR will be described later with reference to FIGS.

《Electric power steering device》
Next, the electric power steering apparatus in the electric steering / electric damper / system of the present embodiment will be described in detail with reference to FIGS.
FIG. 2 is a configuration diagram of the electric power steering apparatus. FIG. 3 is a detailed configuration diagram of a torque sensor used in the electric power steering apparatus.
As shown in FIG. 2, the electric power steering device 301 includes a handle shaft 3 a provided with a steering handle 3, a shaft 3 c, and a pinion shaft 7 connected by two universal joints 3 b, and a lower end of the pinion shaft 7. The pinion gear 7a provided in the section meshes with the rack gear 8a of the rack shaft 8 that can reciprocate in the vehicle width direction, and the left and right front wheels (wheels) 1L are connected to both ends of the rack shaft 8 via tie rods 9 and 9, respectively. 1R is linked.

The pinion shaft 7 is supported at its upper, middle and lower portions by a steering gear box 10 via bearings 3e, 3f and 3g, and a magnetostrictive torque sensor (steering torque sensor) 17 between the bearings 3e and 3f. Is provided.
In the steering gear box 10 described above, a slide bearing 10a for sliding the rack shaft 8 in the axial direction freely is provided inside a rack portion that houses the pinion gear 7a, the rack shaft 8, and the bearing 3g.
With this configuration, the electric power steering apparatus 301 can change the traveling direction of the vehicle when the steering handle 3 is operated. Here, the rack shaft 8, the rack gear 8a, and the tie rods 9 and 9 constitute a steering mechanism.

The electric power steering apparatus 301 includes an electric motor 4 that supplies a steering assist force (auxiliary torque) for reducing the steering force by the steering handle 3, and is provided on the output shaft of the electric motor 4. A worm gear 5 a meshes with a worm wheel gear 5 b provided on the pinion shaft 7.
That is, the speed reduction mechanism 5 is composed of the worm gear 5a and the worm wheel gear 5b. The electric power steering mechanism 25 is constituted by the rotor of the electric motor 4, the worm gear 5a connected to the electric motor 4, the worm wheel gear 5b, the pinion shaft 7, the rack shaft 8, the rack gear 8a, the tie rods 9, 9 and the like. Has been.

The electric motor 4 is, for example, a DC motor with a brush, and converts electric power into mechanical power (P _M = ω _M T _M ).
Here, ω _M is the angular velocity of the electric motor 4, and T _M is the torque generated by the electric motor 4.

Here, the steering torque applied to the steering wheel 3 Ts, the coefficients of the assist amount A _H, which assists the booster has been generated torque of the electric motor 4 via the reduction mechanism 5, for example, changes as a function of vehicle speed VS K _A (VS). In this case, since A _H = k _A (VS) × Ts, the pinion torque Tp applied to the pinion shaft 7 is expressed by the following equation (1).
Tp = Ts + A _H
= Ts + k _A (VS) × Ts (1)
Thus, the steering torque Ts is expressed as the following equation (2).
Ts = Tp / (1 + k _A (VS)) (2)

Therefore, the steering torque Ts is reduced to 1 / {1 + k _A (VS)} times the pinion torque Tp (load). For example, if k _A (0) = 2 when the vehicle speed VS = 0, the steering torque Ts is controlled to be 1/3 lighter than the pinion torque Tp, and k _A when the vehicle speed VS = 100 km / h. If (100) = 0, the steering torque Ts becomes equal to the pinion torque Tp, and is controlled to feel the steering torque with a firm weight equivalent to that of manual steering. In other words, by controlling the steering torque Ts in accordance with the vehicle speed VS, a sense of responsiveness of a stable and stable steering torque is imparted lightly during low-speed traveling and firmly during high-speed traveling.

  The electric power steering device 301 includes a motor drive unit 206 that drives the electric motor 4, a torque sensor 17 that detects a pinion torque Tp applied to the pinion shaft 7, and a vehicle speed sensor 104 that detects a vehicle speed (vehicle speed). And a control ECU 200 that controls the driving of the electric motor 4.

The motor driving unit 206 includes a plurality of switching elements such as an H-type FET bridge circuit, for example, and drives the electric motor 4 using a PWM control signal from the control ECU 200. The motor driving unit 206 has a function of detecting a motor current value supplied to the electric motor 4 (not shown).
The detailed configuration of the motor drive unit 206 will be described in detail in the description of FIG. 8 and FIG.

  The vehicle speed sensor 104 detects the vehicle speed as the number of pulses per unit time, and outputs a signal indicating the vehicle speed VS.

(Torque sensor)
Next, the detailed configuration of the torque sensor will be described with reference to FIGS. 2 and 12 as appropriate with reference to FIG. The torque sensor 17 detects the magnitude and direction of the steering torque Ts applied to the pinion shaft 7, and is a bearing in the lid portion that is flange-joined to the rack portion in the steering gear box 10 (see FIG. 2). In the part above 3f, it is assembled together with the pinion shaft 7 and accommodated together with the bearings 3e, 3f.
Incidentally, the upper end of the pinion shaft 7 is provided with a coupling portion 3k.

As shown in FIG. 3, the magnetostrictive torque sensor 17 is provided coaxially with the pinion shaft 7 between the bearing 3e and the bearing 3f.
The torque sensor 17 has the same configuration as that described in FIG. 1 and FIG. 2 of JP-A-2006-322952, and the outer surface of the pinion shaft 7 is made of, for example, an Fe-Ni-based or Fe-Cr-based positive electrode. A magnetostrictive material having a magnetostriction constant of 2 is formed at two locations in the axial direction by plating, vapor deposition or the like, with a predetermined film thickness, for example, 30 microns or less, and with a predetermined axial interval over the entire circumference in the circumferential direction. The magnetostrictive films 17a and 17b are configured. Moreover, in order to obtain magnetic anisotropies in opposite directions, the pinion shaft 7 is applied by heating with high-frequency heating in a state where a predetermined torque is applied, returning to room temperature, and removing the torque. Thereby, even when no torsional torque is applied to the magnetostrictive films 17a and 17b, the torsional stress is always applied, and the torsional strain is applied. That is, the direction and magnitude of the applied torque are detected.

A detection coil 17c for exciting and detecting the magnetostrictive film 17a with a solenoid shape for the magnetostrictive film 17a of the torque sensor 17 and a solenoid shape for exciting the magnetostrictive film 17b with respect to the magnetostrictive film 17b. A detection coil 17d for detection is also arranged.
In the torque sensor 17, when torque acts on the pinion shaft 7, the torque also acts on the magnetostrictive films 17a and 17b, and an inverse magnetostrictive effect is generated on the magnetostrictive films 17a and 17b according to this torque. When a high-frequency AC voltage (excitation voltage) is supplied from an excitation voltage supply source (not shown) to the detection coils 17c and 17d that perform both excitation and detection, a magnetic field due to the inverse magnetostriction effect based on the torque applied to the magnetostrictive films 17a and 17b. Can be detected as changes in impedance or induced voltage by the detection coils 17c and 17d, respectively. At this time, since the torsional stress is always applied to the magnetostrictive films 17a and 17b in addition to the torsional torque of the pinion shaft 7, the direction of the strain, that is, the torque applied to the pinion shaft 7 (steering) It is possible to detect the direction and magnitude of the torque.
Signals VT1 and VT2 output from the detection coils 17c and 17d, respectively, are input to the conversion circuits 231 and 232 that constitute a part of the input interface unit 112a in the input interface circuit 112 (see FIG. 12), and analog voltage signals ( Torque detection voltage) is further input to the differential amplifier circuit 233, amplified and input to the AD converter 112b (see FIG. 12) in the subsequent stage as the torque detection voltage VT3 which is an analog voltage signal.
Details of the control in the electric power steering apparatus 301 will be described later in the description of the detailed configuration of the control ECU 200.

《Electric damper conversion device》
Next, the electric damper conversion mechanism of the electric damper device will be described with reference to FIGS.
FIG. 4 is a schematic view of a vehicle including a vehicle suspension device to which the electric damper device is applied, as viewed from the back. FIG. 5 is a cross-sectional structure diagram of an electric damper conversion mechanism for the electric damper device. 6 is a partial cross-sectional view taken along line AA in FIG.
Although the rear suspension is shown directly in FIG. 4, the front suspension is basically the same as the rear suspension, except that the wheel support member 13 in FIG. 4 is replaced with a steering knuckle. In FIG. 4, reference numerals in the front suspension are shown in parentheses. Here, in the configuration related to the left and right front wheels, when distinguishing them for explanation, an FL indicating the left front wheel and an FR indicating the right front wheel are appended to the numerical symbol, for example, not simply indicating the wheel 1 but indicating the wheels 1FL and 1FR. In the configuration relating to the left and right rear wheels, when distinguishing for explanation, RL indicating the left rear wheel and RR indicating the right rear wheel are appended to the numerical symbol, for example, the wheels 1RL and 1RR are not simply indicated as the wheel 1. Is displayed. The same applies to the suspension devices 14 related to the other wheels 1 and the configuration thereof.
In the present embodiment, the electric damper device 303 (see FIG. 8, 303FL, 303FR, 303RL, A case where the electric damper conversion mechanism 30FL, 30FR, 30RL, 30RR (shown as 303RR) is provided will be described as an example.

(Suspension device)
As shown in FIG. 4, the vehicle 2 includes a vehicle body 6 having a pair of left and right vehicle suspension devices (hereinafter simply referred to as suspension devices) 14FL and 14FR, and suspension devices 14RL and 14RR. The vehicle body 6 has suspension mounting portions 6a, 6a, 6a, 6a on the front, rear, left and right upper portions. The suspension devices 14FL, 14FR, 14RL, and 14RR are employed as a front suspension or a rear suspension of the vehicle 2, and the left and right wheels 1FL, 1FR, 1RL, and 1RR are suspended from the vehicle body 6.

  The left suspension device 14RL (14FL) is, for example, a dow wishbone type suspension or multi-unit comprising an upper arm 11 and a lower arm 12, a wheel support member 13, and an electric damper conversion mechanism 30RL (30FL). Link suspension.

  The upper arm 11 and the lower arm 12 are connected to a side portion of the vehicle body 6 so as to be able to swing up and down. The wheel support member 13 is composed of a knuckle for rotatably supporting the wheel 1RL (1FL), and is connected to the tip of the upper arm 11 and the tip of the lower arm 12 so as to swing up and down. The left electric damper conversion mechanism 30RL (30FL) has an electric motor 35RL (35FL) at the upper portion, and is spanned between the suspension mounting portion 6a of the vehicle body 6 and the lower portion of the wheel support member 13, so that the wheels 1RL ( 1FL) is damped by the electric motor 35RL (35FL).

  The left electric damper conversion mechanism 30RL (30FL) detects a displacement St (not shown) when the wheel 1RL (1FL) is displaced in the vertical direction relative to the vehicle body 6, as shown in FIG. Displacement amount detecting sensor (position detecting means) 80RL (80FL).

The right suspension device 14RR (14FR) and the electric damper conversion mechanism 30RR (30FR) included in the right suspension device 14RR (14FR) have the same configuration as the left suspension device 14RL (14FL) and the electric damper conversion mechanism 30RL (30FL) except that they are bilaterally symmetric. The description is omitted.
Hereinafter, in order to omit redundant description, a detailed configuration will be described by taking the left-side electric damper conversion mechanism 30RL (30FL) as an example.

(coil spring)
As shown in FIG. 4, the coil spring 36 is a shock absorber that absorbs vibrations and impact forces in the vertical direction while supporting the weight of the vehicle body that has acted on the wheel 1RL (1FL). As shown in FIG. 5, the coil spring 36 is disposed on the lower side of the electric damper conversion mechanism 30RL (30FL), and is disposed at a position separated downward from the electric motor 35RL (35FL) by the rod 32. In other words, the rod portion 42 of the damper housing 31 to be described later is disposed inside the coil inner diameter of the coil spring 36. The upper end 36a of the coil spring 36 is fixed to a spring seat 71 (see FIG. 5) fixed to the upper side of the rod portion 42, and the lower end 36b is a spring seat 72 fixed to the lower end portion 32a of the rod 32 (FIG. 5). Each) is attached individually. The coil spring 36 is interposed between the spring seat 71 and the spring seat 72, thereby biasing the rod portion 42 and the rod 32 of the damper housing 31 in a direction away from each other in the vertical axis direction.

  As shown in FIG. 5, a dust boot 37 covering the open end of the rod portion 42 and the rod 32 protruding downward from the open end is provided so as to be extendable in the axial direction of the rod 32. The dust boot 37 seals the inside of the damper housing 31 from the outside, and seals the opening of the damper housing 31 to prevent intrusion of foreign matters such as dust and prevent rainwater and water on the road surface from entering.

Hereinafter, the detailed configuration of the electric damper conversion mechanism 30RL (30FL) will be described with reference to FIGS.
<Electric damper conversion mechanism>
As shown in FIG. 5, the electric damper conversion mechanism 30RL (30FL) mainly includes a damper housing 31, a rod 32, a rack and pinion mechanism 33, and an electric motor 35RL (35FL).
Here, the rack and pinion mechanism 33 in the present embodiment corresponds to the converter mechanism described in the claims.

  As shown in FIG. 5, the damper housing 31 is a substantially cylindrical member elongated in the vertical direction, and includes a rack and pinion portion 41 and a rod portion 42. The rack and pinion portion 41 and the rod portion 42 are arranged coaxially with each other at one end, for example, press-fitted or welded, and the respective hollow portions communicate coaxially. An upper end side (the other end) of the rack and pinion portion 41 has an end surface portion 41a, has a dish-like insulator 43 and a mounting bolt 44, and is fixed to the suspension mounting portion 6a (see FIG. 4) by the mounting bolt 44. . The lower end (the other end) of the rod portion 42 of the damper housing 31 is open.

As shown in FIG. 5, the rod 32 is formed of an elongated round bar arranged coaxially with the damper housing 31. The rod 32 is accommodated in the damper housing 31, the rack and pinion mechanism 33 accommodated in the rack and pinion portion 41, and the rod portion. It is supported by a slide bearing 45 disposed inside 42 so as to be slidable in the vertical direction. The rod 32 has an end portion 32 a having an annular connecting portion 47 at its lower end, extends downward from the lower end opening of the rod portion 42 of the damper housing 31, and is swingably connected to the lower portion of the wheel support member 13.
The connecting portion 47 may be swingably connected to the lower arm 12.

  A bump stopper 48 made of an elastic material such as rubber is fixed to the end surface portion 41a of the rack and pinion portion 41, and when the upper end surface of the rod 32 collides with the bump stopper 48, the impact is absorbed by the elasticity.

(Rack and pinion mechanism)
As shown in FIG. 6, the motor shaft 35 a (see FIG. 5) is disposed at an upper portion of the electric damper conversion mechanism 30 RL (30 FL) substantially at right angles to the axial direction of the rack gear 51 provided on the outer peripheral surface of the upper portion of the rod 32. It is attached to make. A pinion shaft 53 is connected to the motor shaft 35 a, and the pinion gear 52 provided on the pinion shaft 53 and the rack gear 51 described above constitute a meshing rack and pinion mechanism 33. The rack and pinion mechanism 33 is housed inside the rack and pinion unit 41, and the pinion shaft 53 is rotatably supported at both ends by bearings 54 and 55 fixed to the rack and pinion unit 41.
The electric motor 35RL (35FL) is fixed to the rack and pinion portion 41 by a flange.

  By the way, the rack and pinion mechanism 33 receives a large output from the electric motor 35RL (35FL), and converts the vertical movement into a rotational movement at a high speed when the wheel 1RL (1FL) moves up and down at a high speed. Even in such a case, the meshing state of the rack gear 51 and the pinion gear 52 needs to be reliably maintained. Therefore, each tooth width of the rack gear 51 and the pinion gear 52 is set large.

  As shown in FIG. 6, the rod guide 62 presses the back surface of the rod 32 provided with the rack gear 51 via the sliding member 61, and presses the rack gear 51 against the pinion gear 52. The pressure applied to the rack gear 51 in the direction of the pinion gear 52 is made when the compression coil spring 63 whose urging force is adjusted by the adjustment bolt 64 presses the rod guide 62.

  The rod guide 62 supports the rod 32 from the back side of the rack gear 51 and guides the rod 32 to be slidable in the axial direction. The sliding member 61 is interposed between the rod 32 and the rod guide 62 and directly contacts the outer peripheral surface of the rod 32 on the back side of the rack gear 51 to reduce the sliding resistance. The sliding member 61 is made of a material having wear resistance and low frictional resistance. The lock nut 65 prevents loosening after the adjustment bolt 64 is positioned.

  Thus, by pushing the rack gear 51 in the direction of the pinion gear 52 by the rod guide 62, the play (backlash) between the rack gear 51 and the pinion gear 52 can be set to zero or the minimum, and the rod 32 Even if the vertical motion is a slight vibration, it can be reliably converted into the rotation of the pinion gear 52, and a damping force can be generated in the electric motor 35RL (35FL) with a good response.

(Electric motor)
The electric motor 35RL (35FL) is composed of, for example, a DC motor with a brush, and is attached to the flange portion of the rack and pinion portion 41. As a method of connecting the motor shaft 35a of the electric motor 35 and the pinion shaft 53, for example, connection by serrations as shown in FIG. 6 or elastic connection by coupling (not shown) may be used.

(Displacement detection sensor)
Next, the detailed configuration of the displacement detection sensor of the electric damper device will be described with reference to FIG. 4 as appropriate with reference to FIG. FIG. 7 is a schematic diagram of a displacement detection sensor.
When it is necessary to individually distinguish the displacement detection sensors 80, the symbols FL, FR, RL, and RR are added after the numerical symbol 80 as described above. This is referred to as sensor 80.

  The displacement amount detection sensor 80 includes, for example, a swing rod 82 spanned between the lower arm 12 and the vehicle body 6 and a sensor housing 81 attached to the vehicle body 6 as shown in FIG. By detecting the amount of displacement of the swing angle that swings up and down, the displacement of the vertical movement of the wheel 1, that is, the stroke is indirectly detected.

  Hereinafter, the left displacement amount detection sensors 80FL and 80RL will be described in detail. As shown in FIG. 7, in the displacement detection sensor 80, one end 82 a of the swing rod 82 is rotatably connected to the lower arm 12 (see FIG. 4), and the other end 82 b protrudes from the sensor housing 81. The transmission mechanism 84 is connected to the shaft of the transmission mechanism 84 so as to be rotatable, and the transmission mechanism 84 is connected to, for example, a potentiometer 85 in the sensor housing 81.

  The swing rod 82 itself is composed of an end 82a, an end 82b, a cylindrical adjustment pipe 82c, and a lock nut 82d. In FIG. 7, a female thread is cut on the inner periphery of the adjustment tube 82c on the end 82a side, and the male screw of the end 82a is screwed into the adjustment tube 82c so as to be assembled into a single swing rod 82. When the swing rod 82 is connected to the lower arm 12 and the transmission mechanism 84, the length is adjusted by turning the end 82a. When the length adjustment is completed, the lock nut 82d is tightened to the adjustment tube 82c side to The entire length of the rod 82 is fixed.

  The potentiometer 85 detects the swing angle of the swing rod 82. The potentiometer 85 includes a resistance element 85a and a sliding element 85b. One end of the resistance element 85 a is connected to a constant voltage power supply 87 through a resistor 86. The other end of the resistance element 85a is connected to the ground via a resistor 88. The sliding element 85b can slide on the resistance element 85a in accordance with the swing motion of the swing rod 82. A voltage signal (detection signal of the displacement detection sensor 80) obtained by the sliding element 85b is output from the output terminal 85c. In this manner, the displacement amount detection sensor 80 can detect the displacement amount St of the wheel 1 shown in FIG. 4 via the lower arm 12.

The above description is summarized as follows (see FIGS. 4 to 7).
The suspension device 14 accommodates the rod 32 of the electric damper conversion mechanism 30 and the rod portion 42 on the lower side of the damper housing 31 that accommodates the same on the inner side of the coil inner diameter of the coil spring 36. The rack and pinion mechanism 33 and the electric motor 35 are disposed above the spring seat 71 fixed to the rod portion 42 that fixes the upper end portion 36a.
That is, of the components of the electric damper conversion mechanism 30, only the rod 32 is included in the “unsprung load” of the coil spring 36 and has an extremely lightweight structure.
In addition, unlike the conventional hydraulic damper device, there is no need to provide a large-diameter hydraulic piston inside the coil diameter of the coil spring 36, so that the coil diameter of the coil spring 36 can be set small. The degree of freedom of design of the vehicle 36 can be increased, the size and weight can be reduced, and the compartment of the vehicle 2 can be made larger.

  Furthermore, since the “spring load” (including the vehicle body 6) can be supported by the coil spring 36, the electric motor 35 only needs to control the damper function, that is, the damping force. For this reason, the electric motor 35 can be made small with a small output. Therefore, the entire electric damper conversion mechanism 30 can be reduced in size and weight.

  By reducing the size and weight of the electric motor 35, the mechanical internal loss of the motor itself and the output loss due to the inertia of the rotor can be reduced. For example, the smaller the rotor diameter, the smaller the rotor inertia moment (the moment of inertia is proportional to the square of the rotor diameter). Therefore, when the damping force is controlled by the electric motor, the influence of the mechanical internal loss of the motor itself and the rotor inertia can be suppressed as much as possible, and the relative vertical movement of the wheel 1 with respect to the vehicle body 6 can be controlled with high responsiveness. Since the vehicle can be attenuated, the vehicle can be stabilized and converged smoothly.

  Furthermore, since the electric motor 35 does not move up and down with the wheel 1 when the wheel 1 moves up and down, durability of the electric motor 35 can be improved.

<< Control circuit and electric motor drive circuit for electric power steering, electric damper, system >>
Next, the control circuit and electric motor drive circuit of the electric power steering / electric damper / system 100 will be described with reference to FIGS. 9 and 10 as appropriate with reference to FIG.
The control circuit and the electric motor drive circuit are characterized in that a separate microcomputer is provided for controlling the electric power steering device 301 and electric damper device 303 constituting the electric power steering / electric damper / system 100 for fault diagnosis. However, it is basically performed by one CPU of the microcomputer 113, and the drive circuit of the electric motor (corresponding to motor drive units 106FL, 106FR, 106RL, 106RR, 206 described later) is controlled according to the control signal. .
FIG. 8 is a block configuration diagram of an electric power steering / electric damper / control circuit and an electric motor drive circuit, and FIG. 9 (a) is an example of a bridge circuit constituting an electric motor drive circuit of the electric damper device. It is a figure which shows an H bridge circuit, (b) is a figure which shows an H bridge circuit as an example of the bridge circuit which comprises the drive circuit of the electric motor of an electric power steering apparatus.
As shown in FIG. 8, the control circuit of the electric power steering / electric damper / system 100 and the drive circuit of the electric motor include a battery 101, a main switch 102, a main relay 103, a vehicle speed sensor 104, and each wheel. Displacement detection sensor 80 (shown as 80FL, 80FR, 80RL, 80RR in FIG. 8), control ECU 200, and motor drive unit 106 of each electric damper device 303 (shown as 106FL, 106FR, 106RL, 106RR in FIG. 8) And the torque sensor 17.

  The main switch 102 is composed of, for example, an ignition switch. The main relay 103 includes, for example, a normally open contact 103a connected to the battery 101 and an exciting coil 103b for closing the normally open contact 103a. The main relay 103 is controlled by a microcomputer 113 described later included in the control ECU 200 to drive the relay. Opening and closing operations are performed via the circuit 116.

(Control ECU)
The control ECU 200 controls the electric motor 35 (35FL, 35FR, 35RL, and 35RR in FIG. 8) of each electric damper conversion mechanism 30 based on signals from the displacement detection sensors (indicated as 80FL, 80FR, 80RL, and 80RR in FIG. 8). And a function for controlling the attenuation of the vertical movement of each wheel 1 (see FIG. 4), and an output control function for the auxiliary torque by driving the electric motor 4 based on a signal from the torque sensor 17. Part. The control ECU 200 includes a one-pulse generation circuit 111, a microcomputer 113, an input interface circuit 112 for the input signal, an output interface circuit 114 for an output signal from the microcomputer 113, and a watchdog for detecting a failure of the microcomputer 113. A timer circuit 115, a relay drive circuit 116, and the like are included.

The one-pulse generation circuit 111 generates a one-pulse signal to the microcomputer 113 when the main switch 102 is turned on, and includes, for example, a differentiation circuit.
The input interface circuit 112 includes a half-bridge circuit that converts a resistance change corresponding to a swing angle change of the displacement detection sensor 80 into a voltage, an amplifier circuit, a low-pass filter, a Schmitt trigger circuit that shapes a pulse signal from the vehicle speed sensor 104, A motor current sensor 124 (shown as 124FL, 124FR, 124RL, and 124RR in FIG. 8) described later, an amplifier circuit that amplifies signals from 224, a low-pass filter that removes noise of each signal, and a torque sensor 17 An input interface unit 112a (see FIG. 12) for converting a signal into an analog voltage signal and amplifying the signal, an AD converter 112b (see FIG. 12), and the like are included. These voltage converted or amplified analog signals are converted into digital signals by the AD converter 112b as described above and connected to the input port of the microcomputer 113 as shown in FIG. A pulse-shaped waveform shaped signal such as a vehicle speed signal is directly connected to the input port.
However, the AD converter 112b has a plurality of input terminals and has an analog multiplexer function.
The analog signal that has been voltage-converted or amplified by the input interface unit 112 a may be input to each AD port of the microcomputer 113. In this case, since the function of the input port that can convert the analog signal of the microcomputer 113 itself into a digital signal can be used, the power supplied to the microcomputer 113 is supplied to each AD converter in the microcomputer 113. Supply the same voltage to the other ports. Therefore, there is no variation in digital conversion of signals input to the respective ports during AD conversion.

Returning to FIG. 8, the watchdog timer circuit 115 receives a signal having a constant period from the microcomputer 113 and monitors the signal, and if the microcomputer 113 breaks down and the constant period signal is interrupted, or the signal cycle. Is detected, an abnormal signal is sent to the microcomputer 113, the microcomputer 113 is stopped, the relay drive circuit 116 is stopped, and the main relay 103 is turned off.
When the microcomputer 113 is normal, the watchdog timer circuit 115 outputs a control signal to the relay drive circuit 116 to drive the relay drive circuit 116 and turn on the main relay 103.
In addition, the microcomputer 113 turns off the main relay 103 via the relay drive circuit 116 when an abnormal state is detected by its own fault diagnosis control flow.

  From the output interface circuit 114, a control signal from the microcomputer 113 is output to the relay drive circuit 116, and a control signal for controlling each electric motor 35 for the damper is output to the motor drive unit 106 for power steering. A control signal for controlling the electric motor 4 is output from the motor drive unit 206.

Each motor drive unit 106 for the damper includes a gate drive circuit 121, a bridge circuit 122, a booster circuit 123, and a motor current sensor 124.
As shown in FIG. 9A, when the electric motor 35 is a brushed DC motor, the bridge circuit 122, for example, includes four N-channel enhancement type FETs (Fieid Effect Transistors) 91A. , 91B, 91C, 91D are H-bridge circuits in which switching elements are connected in an H shape.
Similarly, the power steering motor drive unit 206 includes a gate drive circuit 221, a bridge circuit 222, a booster circuit 223, and a motor current sensor 224.
As shown in FIG. 9B, when the electric motor 4 is a brushed DC motor, the bridge circuit 222, for example, includes four N-channel enhancement type FETs (Fieid Effect Transistors) 291A. , 291B, 291C, and 291D switching elements are connected in an H shape to form a so-called H bridge circuit.

Next, a method for controlling the damping force by regenerative power generation in the H bridge circuit of the electric damper device will be described.
FIG. 10 is a diagram for explaining the control states of the four FETs in the damper H-bridge circuit. FIG. 10 (a) is a diagram for explaining the control states of the FETs in the case of regenerative power generation on the expansion side. FIG. 6 is a diagram for explaining the control state of each FET in the case of regenerative power generation on the contraction side.
In the present embodiment, when the electric motor 35 is extended, that is, when the rod 32 (see FIG. 5) moves downward, the motor current to be regenerated is “positive”, and on the contraction side, that is, the rod 32 moves upward. The motor current that sometimes generates regenerative power is defined as “negative”.

The booster circuit 123 is, for example, a circuit in which a transistor, a resistor, and a capacitor are combined. The booster circuit 123 boosts the voltage of power supplied from the battery 101 (see FIG. 8) approximately twice and supplies the boosted voltage to the gate drive circuit 121. The gate drive circuit 121 uses the high voltage supplied from the booster circuit 123, and based on the control signal received from the microcomputer 113 (see FIG. 8) via the output interface circuit 114 (see FIG. 8), Of the FETs 91A to 91D, the gate voltages of the FETs 91A and 91D are controlled so that the FETs 91A to 91D of the H bridge are turned on and off efficiently with a minimum loss.
The on / off control includes PWM (Pulse Width Modulation) control.

FIG. 10 is a diagram for explaining an example of a current flow during PWM control in the bridge circuit, and particularly shows a current flow when the electric motor 35 is caused to generate regenerative power. (A) shows the currents in the on state and off state during PWM control when the electric motor 35 regenerates power when the rod 32 moves on the extension side (downward) and applies a damping force to the extension side movement. FIG. 8B shows a flow, and (b) shows the time of PWM control when the electric motor 35 regenerates power when the rod 32 moves on the contraction side (upward) and applies a damping force to the contraction side movement. It shows the current flow in the on and off states.
In the case of the extension side regenerative power generation, as shown in FIG. 5A, the FETs 91A, 91B, 91C are kept in the off state, and the FET 91D is controlled by the PWM control on / off operation via the booster circuit 123. In the ON state of PWM control, as shown by the solid line (see FIG. 8), the current generated by the electric motor 35 flows from the source side to the drain side by a parasitic diode (not shown) of the FET 91A, and from the drain side to the source side of the FET 91D. Returning to the electric motor 35, the electric motor 35 exhibits a damping force. In the PWM control OFF state, if the inductance of the electric motor 35 itself is L and the current flowing through the electric motor 35 is i, a voltage V sufficiently higher than the battery voltage is generated based on the equation V = Ldi / dt. Thus, the current i from the ground flows from the source side to the drain side by the parasitic diode (not shown) of the FET 91C, flows through the electric motor 35, flows from the source side to the drain side by the parasitic diode (not shown) of the FET 91A, and finally the battery The battery 101 (see FIG. 8) is charged.
If the dt of di / dt is small, that is, if the carrier frequency of PWM is increased, the voltage V can be larger than the battery voltage even if i is small, and regeneration such as a dotted line can be performed.

A method for controlling the regenerative current and damping force generated by the electric motor 35 will be described in a little more detail. Assume that when the electric motor 35 is rotating, for example, as shown in FIG. 10A, the FET 91D is PWM-driven and all other FETs 91A, 91B, 91C are turned off. At this time, the PWM is 100% duty, that is, the FET 91A is kept in the ON state by its own parasitic diode, so that the terminal of the electric motor 35 is practically the same as short-circuited. The current flowing at this time is the flow indicated by the solid line in FIG. At this time, the current flowing through the electric motor 35 becomes maximum, and assuming that it is 10 A, a damping force corresponding to 10 A is generated. Next, if the PWM duty is set to 50%, when the PWM duty is 50% ON (actually, it does not start up immediately due to the inductance L of the electric motor 35, but to simplify the explanation) ) A current of about 10A flows. When the PWM duty is 50% off, a current as shown by a dotted line in FIG. At this time, since the voltage of the regenerative power generation of the electric motor 35 is originally lower than the battery voltage, immediately after switching from on to off, the motor terminal voltage becomes higher than the battery voltage due to the inductance of the motor 35, and a current of 10A flows to the battery. However, since the motor terminal voltage decreases with time, the current converges to 0A. Assuming that the average value of the change in current during the process of the current generated by regenerative power generation from 10 A to 0 A is 3 A, the average value of this current is regenerated in the battery and charged. From the viewpoint of the electric motor 35, the current value in the first 50% on state is 10A, and the current value in the subsequent 50% off state is 3A on average, so the overall average current value is 6.5A. . Since this average current is detected by the motor current sensor 124, if the current flowing through the electric motor 35 is detected by the motor current sensor 124 and the duty is changed so as to become the target current, that is, the duty of the PWM is changed. By controlling the on-time, regenerative power generation can be performed while controlling the damping force of the electric motor 35.
Although the control of the regenerative current and the damping force in the case of the expansion-side regenerative power generation has been described with reference to FIG. 10A, the control of the regenerative current and the damping force in the case of the contraction-side regenerative power generation shown in FIG. Is the same.

In the case of contraction-side regenerative power generation, as shown in FIG. 10B, the FETFETs 91B, 91C, and 91D are kept in the off state, and the FET 91A is controlled by the PWM control on / off operation via the booster circuit 123. In the ON state of PWM control, as shown by the solid line (see FIG. 8), the current generated by the electric motor 35 flows from the source side to the drain side by a parasitic diode (not shown) of the FET 91D, and from the drain side to the source side of the FET 91A. Returning to the electric motor 35, the electric motor 35 exhibits a damping force. In the OFF state of PWM control, a voltage V that is sufficiently higher than the battery voltage is generated based on the above-described equation of V = Ldi / dt, so that a current from ground is supplied to the source side by a parasitic diode (not shown) of the FET 91B. Flows from the source side to the drain side, passes through the electric motor 35, flows from the source side to the drain side by a parasitic diode (not shown) of the FET 91D, and finally flows to the battery side to charge the battery 101 (see FIG. 8).
Here, if dt of di / dt is small, that is, if the carrier frequency of PWM is increased, V can be larger than the battery voltage even if i is small, and regeneration such as a dotted line can be performed.

  The motor current sensor 124 is composed of, for example, a Hall element or a resistor. The motor current sensor 124 detects a drive current actually supplied from the bridge circuit 122 to the electric motor 35 and uses it as a detected current value Id (see FIG. 8) as a control ECU 200 (FIG. 8).

Next, a description will be given of a method for controlling the steering assist force during left-right steering in the H-bridge circuit of the electric power steering device.
FIG. 11 is a diagram for explaining the control state of the four FETs in the power steering H-bridge circuit, and FIG. 11 (a) is a diagram for explaining the control state of each FET in the case of steering to the left side. b) is a diagram for explaining the control state of each FET in the case of steering to the right.
In the present embodiment, the motor current that drives the electric motor 4 to turn leftward is defined as “positive”, and the motor current that drives the electric motor 4 to turn rightward is defined as “negative”.

The booster circuit 223 is, for example, a circuit in which a transistor, a resistor, and a capacitor are combined. The booster circuit 223 boosts the voltage of power supplied from the battery 101 (see FIG. 8) approximately twice and supplies the boosted voltage to the gate drive circuit 221. The gate drive circuit 221 uses the high voltage supplied from the booster circuit 223 and based on the control signal received from the microcomputer 113 (see FIG. 8) via the output interface circuit 114 (see FIG. 8). Of the FETs 291A to 291D, the gate voltages of the FETs 291A and 291D are controlled to control the on / off of the FETs 291A to 291D of the H bridge efficiently with a minimum loss.
The on / off control includes PWM (Pulse Width Modulation) control.

FIG. 11 is a diagram for explaining an example of a current flow during PWM control in the bridge circuit 222. FIG. 11A is a PWM control when the electric motor 4 steers the front wheels 1FL and 1FR in the left direction. FIG. 4B shows the current flow in the on state and off state during PWM control when the electric motor 4 is steered in the right direction. It is a thing.
In the case of leftward steering driving, as shown in (a), the FET 291A is kept on via the booster circuit 223, the FETs 291B and 291D are kept off, and the FET 291C is PWMed at a normal battery voltage. Control on / off operation of control. In the ON state of PWM control, as indicated by the solid line, the current from the battery 101 (see FIG. 8) enters from the input side of the bridge circuit 222, flows from the drain side to the source side of the FET 291A, passes through the electric motor 4, and then passes through the FET 291C. Flows from the drain side to the source side, and finally to ground. In the OFF state of the PWM control, the current that flows from the drain side to the source side of the FET 291A passes through the electric motor 4, then returns from the source side to the drain side of the FET 291D, and returns to the input side of the bridge circuit 222.

  In the case of rightward steering driving, as shown in FIG. 11B, the FETs 291A and 291C are kept off, the FET 291D is kept on via the booster circuit 223, and the FET 291B is a normal battery. The voltage is controlled to turn on / off the PWM control. In the ON state of PWM control, as indicated by the solid line, the current from the battery 101 (see FIG. 8) enters from the input side of the bridge circuit 222 and flows from the drain side to the source side of the FET 291D, and the electric motor 4 is passed through (a). In the opposite direction, the current flows from the drain side to the source side of the FET 291B, and finally flows to the ground. In the OFF state of the PWM control, the current flowing from the drain side to the source side of the FET 291D passes through the electric motor 4 and then returns from the source side to the drain side of the FET 291A and returns to the input side of the bridge circuit 222.

(Control function of electric power steering and electric damper in microcomputer)
Next, control functions in the microcomputer will be described with reference to FIGS. 3 and 8 as appropriate with reference to FIGS.
FIG. 12 is a control function block diagram of the electric power steering / electric damper system 100.
The microcomputer 113 (see FIG. 8) includes a memory such as a ROM, a RAM, and a flash memory (not shown), a CPU, an AD converter, and the like. The microcomputer 113 controls the electric motor 4 included in the electric power steering device 301 and performs electric operation. The electric damper conversion mechanisms 30FL, 30FR, 30RL, and 30RR included in the damper devices 303FL, 303FR, 303RL, and 303RR are controlled by the CPU using a program stored in the ROM and various data stored in the flash memory. The function shown as the control unit 210 in FIG. 8 is executed.
Here, the control unit 210 corresponds to the microcomputer described in the claims.

As shown in FIG. 12, signals from various sensors (torque sensor 17, displacement amount detection sensors 80FL, 80FR, 80RL, 80RR, motor current sensors 124FL, 124FR, 124RL, 124RR, motor current sensor 224) are input interface circuits. 112 is input. Among these input signals, an analog signal is converted into a voltage signal by providing a conversion circuit in the input interface unit 112a of the input interface circuit 112 as necessary, and converted into a digital signal by the AD converter 112b. To the CPU.
For example, the signals VT1 and VT2 from the detection coils 17c and 17d of the torque sensor 17 shown in FIG. 3 are input to the input interface unit 112a as shown in FIG. 12, where there are conversion circuits 231 and 232 (see FIG. 3). ) Is converted into an analog voltage, further amplified in the differential amplifier circuit 233 (see FIG. 3), and input to the control unit 210 via the AD converter 112b.
The pulse signal from the vehicle speed sensor 104 is directly input to the CPU.

The control unit 210 detects a failure such as the torque sensor 17, the vehicle speed sensor 104, and the displacement detection sensor 80 (indicated by 80FL, 80FR, 80RL, and 80RR in FIG. 12) and detects any failure. When the operation is performed, the failure diagnosis unit 201 is provided that outputs an abnormal signal to the relay drive circuit 116 to stop the control of the electric power steering device 301 and the all electric damper device 303.
The failure determination of the torque sensor 17, the vehicle speed sensor 104, and the displacement amount detection sensor 80 in the failure diagnosis unit 201 is, for example, set so that the detection voltage signal falls within a predetermined range when normal, and the torque sensor 17, vehicle speed sensor 104, the case where the signal from the displacement detection sensor 80 does not fall within the predetermined range is determined as a failure.

The control unit 210 includes a damper control unit 202, an electric power steering control unit 205, a damper drive circuit output unit 207, and a power steering drive circuit output unit 209.
Here, the electric power steering control unit 205 and the drive circuit output unit 209 constitute the electric power steering control unit described in the claims, and the damper control unit 202 and the drive circuit output unit 207 include the electric damper control unit described in the claims. Configure.
Specifically, the damper control unit 202 is a generic name for the four damper control units 202A, 202B, 202C, and 202D provided to control the individual electric motors 35FL, 35FR, 35RL, and 35RR, and is similarly driven. The circuit output unit 207 also includes four drive circuit output units 207A, 207B, 207C, and 207D that output respective gate control signals to the motor drive units 106FL, 106FR, 106RL, and 106RR of the individual electric motors 35FL, 35FR, 35RL, and 35RR. It is a generic name.

(Overall control flow)
Next, the entire control flow in the electric power steering / electric damper / system will be described with reference to FIG. 13 and FIG. 8 and FIG. 12 as appropriate.
FIG. 13 is a main flowchart of overall control in the electric power steering / electric damper / system.
When the vehicle 2, for example, a main switch 102, for example, a key switch is turned on, the power supply voltage from the battery 101 is supplied to the control ECU 200. Then, the one-pulse generation circuit 111 in the control ECU 200 detects this power-on, resets the microcomputer 113, and a program preset in the microcomputer 113 operates in synchronization with a clock signal from a crystal oscillator (not shown). Begin.

The following is processing in the control unit 210 (see FIG. 12).
First, in step S01 (each sensor signal reading), the torque sensor 17, the displacement detection sensor 80 (shown as 80FL, 80FR, 80RL, and 80RR in FIG. 12), the vehicle speed sensor 104, and the motor current sensor 124 (124FL in FIG. 12). , 124FR, 124RL, and 124RR), signals from 224 are read.

  In step S02 (failure diagnosis), the failure diagnosis unit 201 performs failure diagnosis of the signal read in step S01. In the failure diagnosis of the torque sensor 17 and the displacement detection sensor 80, for example, the detection voltage is set so as to be within a predetermined range when it is normal, and if it is out of the predetermined range, a failure is diagnosed. The vehicle speed sensor 104 receives a signal from an engine speed sensor (not shown), estimates the vehicle speed, compares it, and diagnoses a failure if it is out of a predetermined range and abnormal. As a result, if a failure is diagnosed, the main relay 103 is turned off via the relay drive circuit 116 to cut off the power supply. If the signal of each sensor is normal, the process proceeds to the next step S03.

In step S03 (calculation of motor control amount of electric power steering and FET driving), the electric power steering control unit 205 is necessary for controlling the electric power steering device 301 based on signals from the torque sensor 17, the vehicle speed sensor 104, and the like. A motor current signal necessary to output a proper auxiliary torque is calculated as a control amount for the electric motor 4, and each EFT 291A to 291D of the bridge circuit 222 is driven based on the result.
In step S04 (calculation of the motor control amount of the electric damper and FET driving), the damper control unit 202 uses the damping force necessary for the damper control as a control amount for the electric motor 35 based on the signal of the displacement detection sensor 80. The EFT 91A to 91D of the bridge circuit 122 is driven based on the calculation result.
Then, the process returns to step S01.
In the main flowchart, each step is described as being performed sequentially, but each step may be processed in parallel. In that case, since the damper control requires high speed, the microcomputer 113 is preferably a multi-core type CPU.

Next, the flow of drive control of the electric motor 4 in the electric power steering control unit 205 and the drive circuit output unit 209 will be described with reference to FIGS. 3 and 11 as appropriate with reference to FIGS.
FIG. 14 is a flowchart showing a flow of drive control of the electric motor for power steering. FIG. 15 is a diagram showing the relationship between the torque detection voltage and the steering torque. 16A is a relationship diagram between the absolute value of the steering torque Ts and the target value (motor current signal Ma) of the motor current of the electric motor for power steering, and FIG. 16B is a diagram of FIG. It is a figure which shows the function of the vehicle speed coefficient Kav multiplied by the motor current signal Ma calculated | required by (a) of (a).
As can be seen from FIG. 16 (a), the target value of the motor current to the electric motor 4 is increased in accordance with the increase of the steering torque Ts. Keep the value constant without increasing it.
Further, as can be seen from FIG. 16B, when the vehicle speed VS becomes equal to or higher than a predetermined value, the vehicle speed coefficient Kav is reduced according to the vehicle speed VS, and the road surface reaction force is strongly transmitted to the driver during high speed traveling, and the steering handle 3 The feeling of operation is made solid.
Incidentally, the data shown in FIGS. 16A and 16B are written in advance in the ROM of the microcomputer 113.
In FIG. 15, the horizontal axis indicates the steering torque Ts, and the vertical axis indicates the torque detection voltage VT3 output from the differential amplifier circuit 233 (see FIG. 3). Incidentally, in the straight lines with VT1 and VT2 in FIG. 15, the signals VT1 and VT2 from the detection coils 17c and 17d (see FIG. 3) are converted into analog voltage signals in the conversion circuits 231 and 232 (see FIG. 3), respectively. Corresponding to the torque detection voltage after that, they are input to the differential amplifier circuit 233, and become the torque detection voltage VT3, that is, the torque detection signal.
Here, in order to simplify the description, basic electric power steering control based on the torque detection voltage VT3 from the torque sensor 17 and the signal indicating the vehicle speed VS from the vehicle speed sensor 104 will be described.

  First, in step S11, the electric power steering control unit 205 calculates the direction and magnitude of the steering torque Ts. For the torque detection voltage VT3 (see FIG. 15) from the differential amplifier circuit 233, Ts = VT3-2.5 is calculated to calculate the steering torque Ts. In step S12, the electric power steering control unit 205 checks whether the steering torque Ts is 0 or more. When the steering torque Ts is 0 or more (Yes), the process proceeds to step S13, where the steering torque Ts = Ts and IFLAG = 0 (step S13). Here, when the steering torque Ts is equal to or greater than 0, it is determined that the direction of operation of the steering torque is neutral or left-turning, and the value of the flag IFLAG indicating the turning direction is set to zero. In step S12, when the steering torque Ts is less than 0 (No), the process proceeds to step S14, where the steering torque Ts = −Ts and IFLAG = 1. Here, when the steering torque Ts is less than 0, the action direction of the steering torque is determined to be right turning, and the value of the flag IFLAG indicating the turning direction is set to 1.

  In step S15, the electric power steering control unit 205 searches the motor current signal Ma based on the steering torque Ts with reference to the data shown in FIG. In step S16, the electric power steering control unit 205 searches the vehicle speed coefficient Kav corresponding to the vehicle speed VS with reference to the data shown in FIG.

  In step S17, the electric power steering control unit 205 sets the motor current signal Ma by multiplying the motor current signal Ma obtained in step S15 by the vehicle speed coefficient Kav obtained in step S16 (Ma = Kav · Ma). .

  In step S18, the drive circuit output unit 209 checks whether or not the value of the motor current signal Ma is 0 and whether or not IFLAG_0 when the value of the motor current signal Ma is not 0 (Ma ≠ 0 ?, IFLAG = 0?) If Ma ≠ 0 and IFLAG = 0, the process proceeds to step S19. If Ma ≠ 0 and IFLAG = 1, the process proceeds to step S20. If Ma = 0, the process proceeds to step S21.

  In step S19, the drive circuit output unit 209 determines that the operation direction of the steering torque Ts is turning leftward, and turns on the FET 291A of the bridge circuit 222 and turns on the FET 291C as shown in FIG. PWM driving is performed at a duty ratio based on the current signal Ma, a command to turn off the FETs 291B and 291D is output to the motor driving unit 206, and the detected current value Is (see FIG. 12) from the motor current sensor 224 is the motor current signal Ma. PID control is performed so as to match.

In step S20, the drive circuit output unit 209 determines that the action direction of the steering torque Ts is turning to the right, turns on the FET 291D of the bridge circuit 222, and turns on the FET 291B as shown in FIG. PWM driving is performed at a duty ratio based on the current signal Ma, a command to turn off the FETs 291A and 291C is output to the motor driving unit 206, and the detected current value Is (see FIG. 12) from the motor current sensor 224 is the motor current signal Ma. PID control is performed so as to match.
In step S <b> 21, the drive circuit output unit 209 turns off all the FETs 291 </ b> A to 291 </ b> D of the bridge circuit 222 and does not output auxiliary torque.
After steps S19, S20, and S21, the process returns to step S04 in the overall flowchart.
In this flowchart, the motor current signal Ma is set only by the steering torque Ts and the vehicle speed VS, but the present invention is not limited to this. The rotational angular velocity of the electric motor 4 may be calculated from the induced voltage of the electric motor 4 and the steering assist force damping compensation may be performed according to the rotational angular velocity.

Next, the flow of control of the damping force generated in the electric motor 35 in the damper control unit 202 and the drive circuit output unit 207 will be described with reference to FIGS. 10 and 12 as appropriate with reference to FIGS.
FIG. 17 is a flowchart showing the flow of damping force control by the damper electric motor. Here, the damping force control in the damper control unit 202 (see FIG. 12) and the drive circuit output unit 207 (see FIG. 12) for one electric motor 35 will be typically described.
18A is a relationship diagram between the absolute value of the displacement speed Sv and the extension side damping force De that is the control target value of the electric motor for damper, and FIG. 18B is the displacement speed Sv. FIG. 18C is a relationship diagram between the absolute value of D and the contraction-side damping force Dc that is the control target value of the damper electric motor. FIG. 18C is a vehicle speed coefficient multiplied by the expansion-side damping force De and the compression-side damping force Dc. It is a figure which shows the function of Kdv.
As can be seen from FIG. 18A, the elongation-side damping force De of the electric motor 35 is increased in accordance with the increase in the absolute value of the extension-side displacement speed Sv, but the elongation with respect to the increase in the absolute value of the displacement speed Sv is increased. The rate of increase (inclination) of the side damping force De is changed depending on the absolute value of the displacement speed Sv, and the inclination on the side where the absolute value of the displacement speed Sv is large is within the range of the absolute value of the predetermined displacement speed Sv including zero. It is set to be smaller than the inclination.

Further, as can be seen from FIG. 18B, the contraction-side damping force De of the electric motor 35 is increased in accordance with the increase in the absolute value of the contraction-side displacement speed Sv. The rate of increase (inclination) of the compression-side damping force De is changed according to the absolute value of the displacement speed Sv, and the inclination on the side where the absolute value of the displacement speed Sv is large is within the range of the absolute value of the predetermined displacement speed Sv including zero It is set to be smaller than the inclination at. The contraction-side damping force Dc is set smaller than the expansion-side damping force De with respect to the same absolute value of the displacement speed Sv.
Here, in FIGS. 18A and 18B, “extension-side damping force De” and “contraction-side damping force Dc” are displayed. Specifically, the electric motor 35 is generated by regenerative power generation. This is the target value of the current value, and the target current value generated during regenerative power generation is collectively expressed as “target damping force Dt” in both cases of the expansion side and the contraction side.

Further, as can be seen from FIG. 18 (c), the vehicle speed coefficient Kdv increases according to the vehicle speed VS when the vehicle speed VS is up to a predetermined value, and is set to a constant value when the vehicle speed VS is equal to or higher than the predetermined value. It is.
Incidentally, the data of (a), (b), and (c) of FIG. 18 are written in advance in the ROM of the microcomputer 113.

First, in step S51, the damper control unit 202 calculates a displacement speed Sv that is a time derivative of the displacement St from the displacement detection sensor 80. Next, in step S52, the damper control unit 202 determines whether the displacement direction is the expansion side or the contraction side based on the sign of the displacement speed Sv. In the case of the expansion side, the process proceeds to step S53, and in the case of the contraction side, the process proceeds to step S55.
Incidentally, when the displacement speed Sv is positive, the displacement direction is determined to be the expansion side, and when the displacement speed Sv is negative, the displacement direction is determined to be the contraction side.
In step S53, the damper control unit 202 searches for the expansion side damping force De based on the displacement speed | Sv | with reference to data as shown in FIG. Next, in step S54, the damper control unit 202 sets the target damping force Dt = De.
In step S55, the damper control unit 202 searches the contraction-side damping force De based on the displacement speed | Sv | with reference to data as shown in FIG. Next, in step S56, the damper control unit 202 sets the target damping force Dt = −Dc.
Here, in step S54, the target damping force Dt is set to a positive value, and in step S56, the target damping force Dt is set to a negative value. In the subsequent step S59, it is possible to determine the extension side damping force and the contraction side damping force. This is because.

In step S57, the damper control unit 202 searches the vehicle speed coefficient Kdv based on the vehicle speed VS with reference to data as shown in FIG. In step S58, the damper control unit 202 sets the target damping force Dt by multiplying the target damping force Dt set in step S54 or step S56 by the vehicle speed coefficient Kdv searched in step S57 (Dt = Kdv · Dt).
In step S59, the drive circuit output unit 207 checks whether the target damping force Dt is 0 or more. If the target damping force Dt is greater than or equal to 0 (Yes), it is determined that the regenerative power generation is on the extension side, and the process proceeds to step S60. If the target damping force Dt is less than 0 (No), it is determined that the power generation is on the contraction side Then, the process proceeds to step S61.

In step S60, the drive circuit output unit 207 turns off the FETs 91A, 91B, and 91C of the bridge circuit 122 as shown in FIG. 10A, and PWM-drives the FET 91D with a duty ratio based on the target damping force Dt. The command is output to the motor drive unit 106, and the detected current value Id from the motor current sensor 124 (see FIG. 12; however, in FIG. 12, Id _FL , Id _FR , Id _RL , and Id _RR are individually displayed) is the target attenuation PID control is performed so as to match the force Dt.

In step S61, the drive circuit output unit 207 sets Dt = −Dt. In step S62, the drive circuit output unit 207 turns off the FETs 91B, 91C, and 91D of the bridge circuit 122 as shown in FIG. 10B, and the PWM of the FET 91A with a duty ratio based on the target damping force Dt. The drive command is output to the motor drive unit 106, and the detected current value Id from the motor current sensor 124 (see FIG. 12; however, in FIG. 12, Id _FL , Id _FR , Id _RL , and Id _RR are individually displayed) is the target. PID control is performed so as to coincide with the damping force Dt.
After the process of step S60 or step S62, the process returns to step S01 of the overall flowchart.

  As described above, according to the present embodiment, for example, signals from the torque sensor 17, the vehicle speed sensor 104, the displacement detection sensors 80FL, 80FR, 80RL, 80RR, the motor current sensors 124FL, 124FR, 124RL, 124RR, 224, etc. Since the signals are input to the two microcomputers 113, there is no variation when the input from the angle sensor is taken. Temporarily, unlike this electric power steering / electric damper / system 100, two microcomputers are provided, and the signal from the torque sensor 17 is sent to one microcomputer to the displacement amount detection sensors 80FL, 80FR, 80RL, 80RR. When the signal is input to the other microcomputer, for example, if the power supply voltage supplied to each AD converter is different, an error occurs that even if the signal has the same value, the captured value is different. May be taken in with a characteristic that the signals from the displacement detection sensors 80FL, 80FR, 80RL, and 80RR become larger. In that case, an uncomfortable combination of an electric power steering device having a heavy steering force and an electric damper device having a soft damping force can be achieved.

On the other hand, for example, a signal from the torque sensor 17 may increase due to a capturing error of the AD converter, and signals from the displacement detection sensors 80FL, 80FR, 80RL, and 80RR may be captured with a small characteristic. . In that case, an uncomfortable combination of an electric power steering device having a light steering force and an electric damper device having a high damping force, that is, a hard riding characteristic can be achieved.
In contrast, in the present embodiment, since the AD converter 112b having the same power supply voltage is passed as shown in FIG. 12, even if the characteristics of the AD converter 112b vary, the electric power steering device 301 and the electric damper Since the same tendency as described above varies among the devices 303FL, 303FR, 303RL, and 303RR, there is no uncomfortable combination.

As a result, the vehicle 2 with a light operating feeling of the steering handle 3 is a luxury vehicle, and a vehicle with a soft ride comfort is preferred, and a vehicle setting that emphasizes the ride comfort is possible.
On the other hand, the vehicle 2 having a heavy feeling of operation of the steering handle 3 is a sporty vehicle, and a vehicle having a high ride comfort is preferred, and it is possible to set a vehicle with a high maneuverability.

  Further, according to the present embodiment, since there is no variation in the clock frequency of the two microcomputers, the torque sensor 17, the vehicle speed sensor 104, the displacement detection sensors 80FL, 80FR, 80RL, 80RR, the motor current sensors 124FL, 124FR are described. , 124RL, 124RR, 224, etc., the variation in the signal level due to the shift in the reading timing of the input signal is also reduced. Furthermore, there is no misdiagnosis of failure diagnosis due to a deviation in reading timing, and the coordinated smooth control between the electric power steering device 301 and the electric damper devices 303FL, 303FR, 303RL, 303RR is stable and there is no misdiagnosis. Actuation can be obtained.

  In this embodiment, the motor drive units 106FL, 106FR, 106RL, and 106RR and the motor drive unit 206 are disposed outside the control ECU 200, and can be disposed near the electric motors 35FL, 35FR, 35RL, and 35RR and the electric motor 4. Thus, the power cable is shortened to reduce the power loss. Further, by enabling such an arrangement, it is possible to suppress the noise from the motor drive units 106FL, 106FR, 106RL, and 106RR and the motor drive unit 206 from affecting the microcomputer 113.

1 is a layout diagram of main components of an electric steering / electric damper system according to an embodiment of the present invention. FIG. It is a block diagram of an electric power steering device. It is a detailed block diagram of the torque sensor used for an electric power steering device. It is the schematic diagram seen from the back surface of the vehicle provided with the suspension device for vehicles to which the electric damper device is applied. It is a sectional structure figure of an electric damper conversion mechanism for electric damper devices. FIG. 6 is a partial cross-sectional view taken along line AA in FIG. 5. It is a schematic diagram of a displacement detection sensor. It is a block block diagram of the control circuit and electric motor drive circuit of an electric power steering / electric damper / system. (A) is a figure which shows an H bridge circuit as an example of the bridge circuit which comprises the drive circuit of the electric motor of an electric damper apparatus, (b) is the bridge circuit which comprises the drive circuit of the electric motor of an electric power steering apparatus. It is a figure which shows an H bridge circuit as an example. It is a figure explaining the control state of four FETs in the H bridge circuit for dampers, (a) is a figure explaining the control state of each FET in the case of expansion side regenerative power generation, (b) is a contraction side It is a figure explaining the control state of each FET in the case of this regenerative power generation. It is a figure explaining the control state of four FETs in the H bridge circuit for power steering, (a) is a figure explaining the control state of each FET in the case of steering drive to the left side, (b) It is a figure explaining the control state of each FET in the case of the steering drive to the right side. 2 is a control function block diagram of an electric power steering / electric damper system 100. FIG. It is a main flowchart of the whole control in an electric power steering and an electric damper system. It is a flowchart which shows the flow which carries out drive control of the electric motor for power steering. It is a figure which shows the relationship between a torque detection voltage and steering torque. (A) is a relationship diagram between the absolute value of the steering torque Ts and the target value (motor current signal Ma) of the motor current of the electric motor for power steering, and (b) is the motor current obtained in (a). It is a figure which shows the function of the vehicle speed coefficient Kav multiplied by the signal Ma. It is a flowchart which shows the flow of damping force control by the electric motor for dampers. (A) is a relationship diagram between the absolute value of the displacement speed Sv and the extension side damping force De that is the control target value of the damper electric motor, and (b) is the absolute value of the displacement speed Sv and the damper It is a relationship figure with the compression side damping force Dc which is the control target value of this electric motor, (c) is a figure which shows the function of the vehicle speed coefficient Kdv which multiplies damping force De and Dc.

Explanation of symbols

1FL, 1FR wheels (steered wheels)
1RL, 1RR Wheel 2 Vehicle 3 Steering handle 4 Electric motor (electric motor for power steering)
DESCRIPTION OF SYMBOLS 5 Deceleration mechanism 5a Worm gear 5b Worm wheel gear 6 Car body 7 Pinion shaft 7a Pinion gear 8 Rack shaft 8a Rack gear 11 Upper arm 12 Lower arm 13 Wheel support member 14FL, 14FR, 14RL, 14RR Suspension device 17 Torque sensor (steering torque sensor)
17a, 17b Magnetostrictive film 17c, 17d Detection coil 25 Electric power steering mechanism 30, 30FL, 30FR, 30RL, 30RR Electric damper conversion mechanism (conversion mechanism)
31 Damper housing 32 Rod 33 Rack and pinion mechanism 35, 35FL, 35FR, 35RL, 35RR Electric motor 36 Coil spring 80, 80FL, 80FR, 80RL, 80RR Displacement detection sensor (position detection means)
81 Sensor housing 82 Swing rod 85 Potentiometer 85a Resistive element 85b Sliding element 85c Output terminal 86 Resistor 87 Constant voltage power supply 88 Resistor 91A, 91B, 91C, 91D, 291A, 291B, 291C, 291D FET
DESCRIPTION OF SYMBOLS 100 Electric power steering * Electric damper system 104 Vehicle speed sensor 106,106FL, 106FR, 106RL, 106RR, 206 Motor drive part (damper motor drive means)
DESCRIPTION OF SYMBOLS 112 Input interface circuit 112a Input interface part 112b AD converter 113 Microcomputer 114 Output interface circuit 124,124FL, 124FR, 124RL, 124RR, 224 Motor current sensor 200 Control ECU
201 Failure diagnosis unit 202, 202A, 202B, 202C, 202D Damper control unit (electric damper control means)
205 Electric power steering control unit (electric power steering control means)
206 Motor drive unit (steering motor drive means)
207, 207A, 207B, 207C, 207D Drive circuit output unit (electric damper control means)
209 Drive circuit output unit (electric power steering control means)
210 Control unit (CPU)
221 Gate drive circuit 222 Bridge circuit 223 Booster circuit 231 Converter circuit 233 Differential amplifier circuit 301 Electric power steering device 303FL, 303FR, 303RL, 303RR Electric damper device

Claims (2)

An electric motor for power steering, a steering torque sensor for detecting a steering torque from the steering handle, and an electric power steering control means for controlling the driving of the electric motor for power steering by at least a signal from the steering torque sensor And an electric power steering device that outputs an auxiliary torque for turning the steered wheels, and a steering motor driving means for driving the electric motor for power steering based on a signal from the electric power steering control means. ,
A conversion mechanism for converting the vertical movement of the wheel into the rotation of the electric motor for the damper, a position detection means for detecting the position of the vertical movement of the wheel, and an electric motor for the damper based on at least a signal from the position detection means Electric damper control means for controlling the damping force by the motor, and damper motor driving means for generating the damping force by the electric motor for the damper based on a signal from the electric damper control means, and the conversion mechanism An electric damper device that attenuates the vertical movement of the wheel;
With
The electric power steering / electric damper system, wherein the electric power steering control means and the electric damper control means are executed on at least one same microcomputer. The microcomputer is
2. The electric power steering according to claim 1, wherein at least a signal from the steering torque sensor and a signal from the position detection means are input to the same AD converter and converted from an analog signal to a digital signal.・ Electric damper system.

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