JPS61196862A - Motor power steering - Google Patents

Abstract

PURPOSE:To improve the steering performance and the steering feeling by constructing the motor power steering device for vehicle such that the transmission torque of clutch is decreased/increased respectively as the car speed will exceed over the predetermined level or decrease below said level. CONSTITUTION:Upon provision of signals from steering torque detecting means 77 and car speed detecting means 86 to a controller, clutch control signal generating means will provide a clutch control signal to correcting means on the basis of the steering torque 77. While car speed decision means will decide whether the car speed has exceeded over predetermined level or dropped below said level on the basis of the steering torque 77 and the car speed 86 to provide an decremental/incremental correction signal respectively upon increase/decrease to correcting means thus to correct the clutch control signal to be predetermined level within predetermined time and to control the clutch drive means 108. With such arrangement, the steering performance and the steering feeling can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric power steering device that controls a steering force booster using an electric motor that generates auxiliary torque in accordance with the speed of a traveling vehicle.

(Prior art) In a general steering device, the steering torque is small when driving at high speeds and increases when driving at low speeds. It is desirable to stop the booster, and an example of such an electric power steering device is ``Japanese Patent Publication No. 3884F3/1983''.

In this electric power steering device, the clutch of the steering force booster is connected and driven when the steering torque is zero when transitioning from high speed driving to low speed driving, and is connected and driven when driving in E or when turning back. On-off control is performed to similarly release the switch when transitioning from driving to high-speed driving, thereby preventing sudden changes in steering torque during steering.

(Problems to be Solved by the Invention) However, in the conventional electric power steering device described above, the clutch of the steering force booster is not driven when the vehicle speed is above a predetermined value or below a predetermined value and the steering torque is zero. Since the configuration is such that when turning from high speed to low speed where the steering torque is not zero, the high speed state is maintained, and the steering force booster is not activated, so at low speed However, the steering force is not reduced, and conversely, when turning from low speed to high speed, the steering force is too light because the steering force booster is activated even at high speed. Furthermore, when there is a sudden steering change, the steering torque passes through zero, so the steering force booster suddenly activates (
(high speed → low speed) or released (low speed → high speed). As a result, there is a problem that the steering stability and steering feel are deteriorated.

(Object of the Invention) Therefore, the present invention provides that when a steering torque is applied,
When the traveling vehicle speed increases beyond a predetermined value, the transmission torque of the clutch means is decreased over time and then brought to zero, and when the vehicle speed decreases beyond a predetermined value, the transmission torque of the clutch means is determined over time. The purpose of this is to improve steering stability and steering feel by increasing the steering performance.

(Means for solving problems and their effects) FIG. 1 is an overall configuration diagram of the present invention.

In the device of the present invention, when the key switch of the ignition key is turned on, each detection signal is output from the steering torque detection means (77) and the vehicle speed detection means (88). When the steering wheel is steered, the clutch control signal generating means determines the transmission torque of the clutch based on at least the steering torque detection signal of the steering torque detecting means (77) and outputs it as a clutch control signal. On the other hand, the vehicle speed is determined in the vehicle speed determination means based on the steering torque detection signal and the vehicle speed detection signal from the vehicle speed detection means (8B), and if the vehicle speed increases beyond a predetermined value, a reduction correction signal is output. , if the vehicle speed decreases beyond a predetermined value, an increase correction signal is output. In the correction means, the reduction correction signal causes the transmission torque of the clutch means to gradually decrease at a predetermined rate to zero, and the increase correction signal causes the transmission torque to decrease from zero to a predetermined rate. An incremental correction is then made to gradually increase the required transmission torque to the determined value. The clutch means is then driven by the clutch drive means (108) based on the corrected control signal.

(Embodiment) A preferred embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 2 is a longitudinal cross-sectional view showing the electromagnetic booster of this embodiment bent at 90°. In Figure 2, (1)
is a steering column, (2) is a stator, (3) is a case, and (4) and (7) are an input shaft and an output shaft arranged coaxially with each other. The device has an input shaft (0) whose inner end is the output shaft (7
), while these inner ends are connected by a torsion bar (8), and the input shaft (0 is connected to the bearing (9)
), (10), and (11), the output shaft (7) is connected to the bearing (
IIA), (13), and (13A), each of which is rotatably supported. Furthermore, a steering rotation sensor (20) arranged around the input shaft (0), an input/output shaft (4) and (
The steering torque sensor (2) disposed around the fitting part of (7)
4) and an electric motor (33) disposed around the output shaft (7).
), the electric motor (33) and the electromagnetic clutch (63) based on detection signals from the reduction gear (50), the electromagnetic clutch (clutch means) (83), the steering rotation sensor (20), and the steering torque sensor (24). This configuration includes a control device (75) that performs drive control.

More specifically, the input shaft (0) is divided into a first shaft (5) and a cylindrical second shaft (6), and a handle is attached to the outer end side (right end side in the figure) of the first shaft (5). The steering wheel is fixed to the steering wheel, and there is a rubber bushing on the inner end to prevent vibration transmission.
A cylindrical second shaft (6) is connected via the shaft (14). Further, as shown in FIG. 3, the first shaft (5) has an annular member (1) having a protrusion (15a) protruding in the radial direction.
5) is fixed in one piece, and the protrusion (15a) is connected to the second shaft (6).
) Notch groove (8a) formed on one end side (right end side in the figure)
is inserted with an appropriate gap. Therefore, the first shaft (5) and the second shaft (6) are elastically connected by the rubber bush (10), and after being twisted by a predetermined angle due to the gap, the first shaft (5) and the second shaft (6) is engaged, and the structure is such that no load exceeding a predetermined torque is applied to the rubber bush (14) in the torsional direction.The circlip (16) is for preventing W.

Also, on the other end side of the second shaft (6) (left side in the figure), there is a
As shown in Figures (a) to (c), the groove (17
) are formed at 180° intervals, and the output shaft (7) has an enlarged diameter.
Projecting pieces (7a) are inserted into the six grooves (17) at a predetermined interval from the inner end side of the second shaft (8), and project from the inner end side of the second shaft (8). ) is supported within the enlarged diameter portion of the output shaft (7) via a bearing (11). Furthermore, the second shaft (6) and the output shaft (
A torsion bar (8) is installed in the hole formed on the inner end side of the
) is arranged along the axis, and one end side (right end side) of this torsion bar (8) is fixed to the second shaft (6) by a pin (18), while the other end of the torsion bar (8) It is fixed to the output shaft (7) by a side pin (19). The outer end side of the output shaft (7) is connected to another shaft on the load side by a spline formed therein. Therefore, the steering torque applied to the input shaft (0) by the steering wheel is
It is transmitted to the output shaft (7) and the load side through the torsion of the torsion bar (8). In addition, the above rubber bush (14)
The rigidity of the torsion bar (8) is higher than that of the torsion bar (8).

The steering rotation sensor (20), as shown in FIG.
A plurality of protrusions (21) protrude from the outer periphery of the second shaft (6) at equal intervals in the radial direction, and a photocoupler ( The photoelectric pickup (22) receives transmitted light interrupted by the protrusion (21),
This received light is converted into a pulsed electrical signal and output.

The steering torque sensor (20) includes a cylindrical movable iron core (25) provided on the outer periphery of the fitting portion between the second shaft (8) and the output shaft (7) so as to be displaceable in the axial direction, and a steering column (1). ) The movable iron core (25) is constructed of a differential transformer consisting of a coil part (2B) fixed to the inner circumference.
As shown in a) to (C), each protrusion (7) of the output shaft (7)
The pins (28) protruding from a) and these pins (26)
) and a long hole (25a) and (25
b). The elongated hole (25a) is formed along the axial direction, while the elongated hole (25b) is formed inclined at a predetermined angle with respect to the axial direction. Therefore, the second axis (
6) and the output shaft (7) in the circumferential direction, the elongated hole (25b), the pin (2B) and the elongated hole (25a)
Due to the engagement relationship between the pin (27) and the pin (27), the movable core (25) moves in the axial direction, and the movable core (25) is displaced in response to the steering torque applied to the second shaft (6). . Further, a coil section (28) provided around the movable iron core (25) includes a primary coil (29) to which a pulse signal is input.
) and a pair of secondary coils (30, 31) disposed coaxially on both sides of a primary coil (29) that outputs an output signal corresponding to the displacement of the movable iron core (25). As the torsion bar (8) twists, the second axis (
6) and the output shaft (7), the axial displacement of the movable iron core (25) is converted into an electrical signal and output.

Next, the electric motor (33) includes a cylindrical stator (2) that is integrally fixed to the steering column (1) and the case (3) by bolts (30), and this stator (2).
at least a pair of magnets (36) fixed to the inner surface of the
A rotor (3) rotatably disposed around the output shaft (7).
7) is rotatably mounted on the output shaft (7) via bearings (12) and (13), and is rotatably mounted on the output shaft (7) via bearings (IIA) and (13A). Cylindrical shaft (38) supported by stator (2) and case (3)
On the outer periphery of this tube sleeve (38), there is an iron core (39) having a skew groove, multiple windings (four windings are sequentially wrapped in a single body, and the magnet (3B) and the multiple winding (41) A small air gap is provided between them.
) is equipped with a commutator (43) connected to the multiplex winding (41). Furthermore, brushes (46) that come into pressure contact with the commutator (43) are housed in brush holders (47) fixed to the case, and lead wires connected to the brushes (4B) are passed through non-magnetic pipes to the stator (2). ) is taken out to the outside. In addition, multiple winding (41), commutator (4
3) and the brush (46) constitute an electric motor (33) that generates auxiliary torque.

The speed reduction device (50) includes a two-stage planetary gear mechanism (51) and (52) arranged around an output shaft (7). The planetary gear mechanism (51) at the front stage includes a common internal gear (53) formed on the inner circumferential surface of the case (3) and the sleeve sleeve (3).
8) A sun gear (38a) formed on the outer periphery of the other end (left end in the figure) and three planetary gears (5) meshed with these.
4), and a first carrier member (50) that pivotally supports the planetary gear (50).
55), a planetary gear mechanism (52) in the latter stage is mounted around the shared internal gear (53) and the output shaft (7), and is integrally connected to the first carrier member (55). A sun gear (58a) formed on the outer periphery of the cylindrical body (5B)
, three planetary gears (57) that mesh with these, and a second carrier member (5) that pivotally supports these planetary gears (57).
day). Additionally, this second carrier member (58)
A cylindrical body (60) supported by the output shaft (7) is integrally connected to the inner edge side of the case (3) via a bearing (59), while a cylindrical body along the inner circumference of the case (3) is attached to the outer edge of the cylindrical body (60). (61) are connected in one piece, and internal teeth (81a) are formed in the circumferential direction on the inner peripheral surface of this cylinder (at). Therefore, the electric motor (
When the rotor (37) of 33) rotates, the rotor (37)
The rotation of the tube sleeve (38), the planetary gear (50), the first carrier member (55), the planetary gear (57), the second carrier member (
58) and is transmitted to the cylinder (61) while being decelerated.

The electromagnetic clutch (83) has a rotor (64) that
Ring body (85) splined to the outer periphery of the output shaft (7)
The output shaft (7) is rotatably supported via a bearing (86), and is fixed to the output shaft (7) via an annular elastic member (67) that absorbs torsional vibrations. Further, the rotor (64) is formed in a cylindrical shape, and the cylindrical body (
A pair of projections ( 84
a) is provided protrudingly. As shown in FIG. 6, these protrusions (64a) are inserted into notched grooves (85a) formed in the ring body (65) with a required gap in the circumferential direction, and It has an engagement relationship with the ring body (65). Therefore, the rotor (B4) and the output shaft (7) are located within the gap, that is, the protrusion (84) of the rotor (80).
Until a) and the ring body (65) are engaged, they are in an elastically connected state.

Further, external teeth (64) are provided on the outer periphery of the extending portion of the rotor (64).
b) is formed, and a disk-shaped support plate (64) is formed at a position on the opposite side of the second carrier member (58) of this extension part.
c) is provided protrudingly. This support plate (f14c) and the second
A disc-shaped plate (68) having a groove on its outer periphery that engages with the inner part (81a) of the cylindrical body (61) and the outer tooth (84b) of the rotor (64) are provided between the carrier member (58) and the outer tooth (84b) of the rotor (64). ) are arranged alternately to form a multi-plate clutch mechanism. Note that (70) in the figure is a stopper for the play (89). Furthermore, a frame body (71) having a U-shaped longitudinal section is fixed to the case (3), and a ring-shaped excitation coil (72) is housed within this frame body (71).
is controlled through the lead wire! (75). Therefore, due to the electromagnetic force generated as the excitation coil (72) is energized, play) (89) and (68)
is attracted to the excitation coil (72) side, so the deceleration device (
The rotational torque of the electric motor (33) transmitted through the multi-disc clutch mechanism and the protrusion (6) of the rotor (64)
4a) to the output shaft (7).

Next, the control device (75) will be explained based on FIG. 7.

In FIG. 7, (76) is a microcomputer, and the microcomputer (76) includes a steering torque detection means (77), a steering rotation detection means (82), a vehicle speed detection means (86), and an abnormality detection means (114). Detection signals S1 to SO are input.

The steering torque detection means (77) includes the steering torque sensor (24) and a drive unit that divides and outputs the clock pulse T1 inside the microcomputer (76) to the primary coil (28) of the steering torque sensor (20). 2t (
7B), rectifier circuits (79A) and (79B) that rectify each electrical signal obtained from the secondary coils (30) and (31) in response to the displacement of the movable core (25), and remove high frequency components. Low pass filter (80A), (8
0B), this low-pass filter (8QA), (80B
) and an A/D converter (81) that converts each analog electrical signal from the converter into a digital signal and inputs the signal as a steering torque detection signal S, , S, to a microcomputer (76). The steering rotation detection means (82) includes the steering rotation sensor (20) and the steering rotation sensor (20).
) in the photocoupler (22), power is supplied to two light emitting parts whose phases are different by about 90 degrees with respect to the protrusion (21) of the second axis (6), and light reception facing each light emitting part is performed. a pulse conversion circuit (83) that converts the electrical signal output by the section into an appropriate pulse signal and outputs it; a waveform shaping circuit (80) that shapes this output signal; and a waveform shaping circuit (84) that Pulse signal and microcomputer (76
), a steering speed signal having a frequency proportional to the steering rotational speed is sent to S3 or S4. depending on the steering direction. For example, as shown in FIG. 13, in clockwise rotation, the pulse signal proportional to the steering rotation speed changes from 33 to S.
=0, and conversely, in the case of counterclockwise rotation, a drive unit (85) outputs a signal from S4 from a pulse signal proportional to the steering rotational speed, and in this case, 5ff=O. Further, the vehicle speed detection means (86) includes, for example, a magnet (86) that rotates together with the speedometer cable.
A vehicle speed sensor (89) consisting of a reed switch (88) that is intermittent as the magnet rotates, and a vehicle speed sensor (89) that supplies power to the reed switch (8) and outputs the intermittent reed switch (88) as a pulse signal. Pulse conversion circuit (90
) and a waveform shaping circuit (
The output signal S from this waveform shaping circuit (91) is a pulse signal with a frequency proportional to the vehicle speed.

The microcomputer (78) is composed of an I10 board, a memory, an arithmetic section, and a control section. Also,
Power supply circuit that drives the microcomputer (76) etc.
32) connects the ignition key key switch (94) and fuse (95) to the child terminal of the vehicle battery (93).
It consists of a relay circuit (9B) connected through the relay circuit (9B), and a constant voltage circuit (97) connected to the output side of the relay circuit (86). Power is supplied to the electric motor drive means (100) and the electromagnetic clutch drive means (108), and the constant voltage circuit (
Power is supplied from the B terminal of 97) to the microcomputer (76) and other control units. Therefore, when the key switch (94) is turned on, the microcomputer (76) detects each of the input detection signals (S+ to S
s) according to a program written in the memory, and the control signal T3.s) is processed to drive the electric motor. “r, ”r, and the current control signal Te for driving the electromagnetic clutch are applied to the motor drive means (100) and the electromagnetic clutch drive means (100).
08) to drive and control the electric motor (33) and electromagnetic clutch (63).

The electric motor drive means (100) includes a drive unit (10
1), relays (102, 103) and transistors (
104, 105). Bridge circuit! ±relay r102))-r10
The connection part 3) is connected to the A terminal of the power supply circuit (92), and the emitters of the transistors (+04) and (105) are connected to the common side (7-) via the resistor (1013). . The excitation coil of each relay (102, 103) and the base of the transistor (104, 105) are connected to the output side of the drive unit (101), and each transistor (104) and (105) are connected to the output side of the bridge circuit.
) of the motor (33) is connected between the collectors of the armature winding (
41) is connected. said drive unit) (+
01) is the control signal T3 from the microcomputer (7B).

Turn on relay (102) or (+03) based on T4
, the transistor (105) or (104) is brought into a drive removable state, and the control signal T5 performs pulse width conversion (
PWM modulated) pulse signal is transmitted to the transistor (104,
105).

Therefore, in the motor drive means (100), one relay (1o2) and the transistor (105) are energized, or the other relay (103) and the transistor (103) are energized.
The direction of rotation of the electric It (33) is controlled by energizing the transistor (4), and the transistor (104, 105) is controlled by a pulse signal applied to the novel base.
104, 105) PWM control is performed. A voltage (A terminal) with a pulse width according to PWM control is applied to the electric motor (33), and the electric motor (33) is controlled to generate an auxiliary torque corresponding to the steering torque applied to the steering wheel. Ru.

The electromagnetic clutch drive means (108) consists of a drive unit (109) and a transistor (110).

The collector of the transistor (110) and the power supply circuit (8)
The excitation coil (72) of the electromagnetic clutch (63) is connected between the A terminals of 2). The emitter of the transistor (110) is connected to the common side through the resistor (111), and the base is connected to the output side of the drive unit (109). Furthermore, the drive unit (109) outputs a pulse signal whose pulse width has been converted based on the control signal T4 to the transistor (110).

Therefore, in the electromagnetic clutch drive means (to8), the drive unit (109) performs PWAA control of the transistor (11G) based on the current control signal T4 from the microcomputer (76), and accordingly, the electromagnetic clutch ( The torque coupling force of 83) is controlled.

Further, in this embodiment, an abnormality detection means (11) for detecting abnormality of the electric motor (33) and the electromagnetic clutch (B3)
4). This abnormality detection means (110) includes an amplifier (115A) that amplifies the terminal voltage of the resistor (10B) and an amplifier (115A) that amplifies the terminal voltage of the resistor (111).
B), low-pass filters (118A) and (118B) that remove high frequency components, and a microcomputer (7) that converts these detected voltages into digital signals SO.
B) is comprised of an A/D converter (117) that inputs input to the A/D converter (117). This abnormality detection means (110) detects an abnormality in the electric motor (33) or the electromagnetic clutch (B3) by each resistor (110).
t OS) and (111), and in case of abnormality, the relay circuit (98) of the power supply circuit (92) is detected.
It is used for abnormality diagnosis, etc. to output a relay control signal T2 to stop the supply of power from the power supply circuit (92).

Next, the effect will be explained.

FIG. 8 is a flowchart showing an outline of the electromagnetic clutch control processing according to the vehicle speed in the microcomputer (76), and P1 to P43 in the figure indicate each step of the flowchart.

When the key switch (94) of the ignition key is turned on, power is supplied to the microcomputer (76) and other circuits to start control. First, in the microcomputer (7B), each register, RAM (
Zero all cheaters in random, access, memory),
That is, clear it. Then, in step P1, the steering torque detection signals S1 and 32 are sequentially read, and in step P2, it is diagnosed whether the read values are normal or not. Stops the operation and returns to manual steering. Here, since the torque sensor (24) is composed of a working transformer, the steering torque Ts and 5. , Sl are shown as shown in FIG. 14, and it is well known that the sum of Sl and 57 is a constant value. So (S 1+ 32) /
2 is within a predetermined width, and if it is not within the predetermined width, it is determined that the torque sensor is malfunctioning.

If the read steering torque detection signals S, , S, are normal, the process advances to step P3, where S, -S,
is calculated and stored as the steering torque T (=Ts).

Next, a detection signal S3 from the steering rotation detection means (82),
S, are sequentially read, and in step P5, each tsi,
t54 is sequentially measured, and in step P, the difference t between them is calculated in order to determine the rotation direction.
-t54 (t5.=0).

A table (1) in which the motor control signal T is stored is configured in the memory with the steering torque T as the upper address and the period t as the lower address. Here, since the control signal T5 is for PWM driving the electric motor drive (100), the duty ratio ("H" engine ratio during 1 cycle) is stored. Duty ratio (T is the multiple winding (41)) The resistance of the motor is RM, the induced voltage constant is K, the rotational speed of the motor is N, the armature power supply is IM, and the power supply voltage is expressed by the following patents: In the case of an electric power steering device, it is preferable that the armature current I corresponds to the steering torque and the motor rotation speed N corresponds to the steering rotation speed. If the proportional relationship is set as shown in Figure 9, and the steering rotation speed Ns and the motor rotation speed N are set in a proportional relationship as shown in Figure 10, then (K+, where 2 is a proportionality constant) is expressed as By storing this in the table l, T5 can be immediately called by addressing using the well-known t corresponding to the steering torque T and the steering rotational speed Ns.The value of the duty ratio is stored in the microcomputer (78). is stored as an 8-bit parallel signal, and the duty ratio can be programmably varied by this 8-bit parallel signal.This circuit generates a series pulse T5 with the duty ratio stored in the triple L. is output.Therefore, although the fresh fish signal T5 actually output from the microcomputer (7B) and the duty ratio processed inside the microcomputer (76) are different, they have the same meaning, so they will be treated as equivalent below. .

It is determined in step P8 whether or not the control signal T has a value, and if it is positive, the control signal (motor rotation direction) is stored with the processing of T3=l and T4=0 (clockwise rotation). If it is negative, the process proceeds to step P♂, where the control signal T is converted to a positive value, and the (motor rotation direction) control signal is changed to "r,=o".

Store T4=1 (clockwise rotation).

Next, in step P, 2, the control signal T5 is set, and in step P13, it is determined whether T5 is positive, and if it is negative,
Or if it is zero, jump to step P14, output the (motor rotation direction) control signal with T3=T4=O, and relay (102, 103), transistor (104, 10
5) respectively to 0FFL, and control signal T5 at step P15.
. The output to T is stopped, the operation of the electric motor (33) and electric clutch (B3) is stopped, and the process returns to step P1. That is, if the control signal T5, which maintains the manual steering state, is positive, the process proceeds to step P16, where the control signal T3.
Output T, and set T,=1. If T4=O, relay (10
2) is turned on to make the transistor (105) controllable, and when T, = O, T4 = 1, the relay (10a3) is turned on.
In step P17, which sets the N transistor (104) in a controllable state and proceeds to step P17, a predetermined value is further subtracted in order to provide a second dead zone, and the result is processed to be the control signal T. In PI8, it is determined whether T5 is positive or not, and if it is negative or zero, step P1
Jump to 5 (control signal T5.

T8 is respectively set to zero to stop the operation and return to step P1.

If the control signal T5 is positive, proceed to step P19.If it is 0 or more, the control signal Tz, T4 for the motor rotation direction is output, and the control signal T5 for the motor power is determined (hereinafter referred to as a determined value) and output. It is in a state where it is only waiting for processing. Here, the reason why the first negative band and the second dead band are provided in the control signal T5 is that relays have a large activation delay compared to transistors, and if they are activated simultaneously with the control signal T5, the duty ratio of the control signal T5 will change from zero to the output. This is to prevent the steering torque from suddenly decreasing from a certain value and reducing the steering feeling.

Next, the operation of vehicle speed control according to the present invention will be explained.

In step 2 PI9, the detection signal S5 from the vehicle speed detection means (86) is read, and in step P20, the cycle t of the read signal S5 is measured. Vehicle speed signal SS
Since is a frequency proportional to the vehicle speed, the period t-ma also corresponds to the vehicle speed.In the zero-order step P21, it is determined whether the period t-ma is smaller than a predetermined value. When the vehicle speed is greater than a predetermined value, the period t is smaller than the predetermined value C, and when the vehicle speed is smaller than the predetermined value, the period t is larger than the predetermined value C. Therefore, if the vehicle speed is smaller than the predetermined value, the period t is the predetermined value C.
Since it is larger, the process proceeds to step P22. Here, signals A, F, and G for storing the previous control state are provided inside the microcomputer (7G). When F=G-0, it is a low-speed stable region, that is, a region where control is performed using the determined value T5, and when F=G=1, it is a high-speed stable region, that is, the motor control signals T3, T4, T1. The electromagnetic clutch control signal Te and the electromagnetic clutch control signal Te are all zero, and the operation is stopped. Also, F=1. G=0 is low speed or high speed unstable region,
In other words, the vehicle speed exceeds a predetermined value and the control signal "r," T6 is being reduced over time but has not yet been reduced to zero, or the vehicle speed has fallen below a predetermined value and the control signal "r" , is in the process of increasing with time and has not yet reached the control state up to the determined value, and A indicates a correction value.In step P22, it is determined whether or not the previous control was in a high-speed state. Determine. Since the first data are all set to zero at the start, the processing of F=0 is performed and after indicating the low speed stable region, the process proceeds to step P24, where the abnormality detection means (114
The detection signal So corresponding to the motor armature current I M- from ) is read, and in step P25, a table 2 in which the calculated value of is stored is configured in the memory whose address is the detection signal SO. Here, since the armature radio wave IM of the electric motor corresponds to the steering torque T as shown in FIG. 11, Te, that is, the clutch control signal also corresponds to the steering torque T. Here too, the microcomputer (7
B) includes a circuit in which the value of the duty ratio is stored as an 8-bit parallel signal, and the duty can be programmably varied using the 8-bit parallel signal;
This circuit outputs a series pulse T having the duty ratio stored in table l. Therefore, although the control signal Te actually output from the microcomputer (7B) and the duty ratio processed inside the microcomputer (76) are different, they have the same meaning, so they will be treated as "between" below. In step P25, the detection signal S is detected. A control signal Te having a pulse width proportional to the armature current corresponding to the steering torque signal is set from Table 1 with the address T6, and the process proceeds to step P26. outputs and drives the electric power steering device using PWM.

In step P2□, the detection signal Se from the detection means (114) is compared with the control signals T, Te, and if they are not within a predetermined range, the relay circuit (98) is turned off by the control signal T2. The system stops all controls and returns to manual steering. If the width is within the predetermined range, the process returns to step P and repeats the same control.

Next, the vehicle speed exceeds a predetermined value and the periods t, s of the detection signal S,
becomes smaller than the predetermined value C, step P21
The process proceeds to step P28 through the determination process.

Signal processing F=1 is performed to indicate that the vehicle speed has exceeded a predetermined value, and the process proceeds to step P29. Here, it is determined whether the previous control was in the high-speed stable region, and now the previous control is in the low-speed stable region. Since it happened, G=O. Therefore, the process proceeds to step P2°, and at step horse 0, the correction value A is subtracted from the control signal T5, but now A=O.
Therefore, in step P31 at T5, the process proceeds to step P32 where the addition process of A=A+1 is performed and the fact that step P:IO has been passed once is stored. In step P32, it is determined whether the control signal T5 is positive or not. If it is positive, it is still necessary to decrease T5, so the process jumps to step P24, and step P24. P2. Table 1 shows the control signal Te in
At call step P26, the PWM control signals T, , T
e is output, and if the failure diagnosis is 1 in step P27, the process returns to step P1. Then it reaches P2O again and T
5=T<1, T5 is decreased by 1 from the determined value at step P3Q, and each time T is passed through R3+, T is decreased by 1, and T is also decreased by 1 at step P2.
4. At P25, the reduced auxiliary torque of the motor is reduced over time corresponding to the armature current. When T5 becomes zero, it is determined in step P3° and the process proceeds to step P33, where after setting the reduced pressure value A as a tree, the confidence %G indicating the high liao stability region is set to 1, and in step P34, T5 is determined.
1=T4 ="r, ="r, ==Q is output, the operation of the electric power steering device is stopped, and manual steering is returned. If the failure diagnosis is normal in step P35, the process jumps to step P19. In the high-speed stable region, steps P28, P2O, P33, and P34 are performed based on the determination in step P21.

P35. P19. It repeats the P2o loop and functions as a constant manual steering wheel.

Next, the vehicle speed drops from the high-speed stable region to a predetermined value, and it is determined in step P21, and the process proceeds to step P27, where F=
1, so it jumps to step P36 based on the determination in step P23, and here it is determined whether or not the previous state was in the high-speed stable region.Since the previous state was in the high-speed stable region, G=1, and the process advances to step P37. It is determined whether the increase correction value A of the control signal T5 has reached the determined value, and since it was in the announcement stable region last time, A=0 is processed in step PJ3. Therefore, in the determination at step P37, since A is smaller than TS, the process proceeds to step P38, and after processing T5=0, step P3
At step 8, the increase correction value A is increased by l, and the control signal T6 is transferred to step P24 through step P25.
is called from table l, and in step P26, P
Output the WM control signals "r,,"re, and proceed to step P27.
If the failure diagnosis is normal, the process returns to step P1. Then, the process reaches step P38 again, where T5=1 is processed, and TS is corrected to increase by 1 from the previous value.
It is increased over time each time steps P38 and P39 are passed, and Te is also increased over time in response to the increased auxiliary torque of the motor, that is, the armature current, in steps P24 and P25. Then, when the control signal T5 is corrected to increase to the determined value, A=T5 in step P37.
The vehicle then jumps to step P23 and enters the low-speed stable region. Control is performed using the determined value, and the electric power steering device operates normally.

Next, the low speed or high speed unstable region will be explained.

This unstable region is an unstable region in which the vehicle speed oscillates around a predetermined value, and for example, when transitioning from low speed to high speed, the vehicle speed exceeds the predetermined value, starts reducing correction of "r," and "r", and still ends. If the vehicle speed decreases again before the vehicle speed is finished, or when the vehicle speed drops below the predetermined value when changing from high speed to low speed, an increase correction of T, T, is started, and if the vehicle speed exceeds the predetermined value again before the vehicle speed completes. This enables smooth control.

When the vehicle speed exceeds a predetermined value from a low speed state, that is, A=F=G=0, steps P2°, P28. P2O.

P. , P31 , PI3 , P24 ” 25 ”
26 ” Control is performed via 27, and this is performed, for example, by
If it is repeated 0 times, A=0 and TS is output as TS-9 for the determined value, and Te is correspondingly decreased along with the armature current. 0 Next, when the vehicle speed decreases and falls below a predetermined value, a step is performed. After passing through P22, P23, and P36, the process jumps to step P40, where A=A-9, that is, A=9, is calculated. After going through steps P and 11, B=T, -9 is calculated, which matches the previous value. Then, in step P4□, it is determined whether B, that is, the control signal, is smaller than the previously determined value. Here, since B is smaller than TS by 9, the process advances to step P43 and transfers B to T.

Jump to step P21, step P21. P25
The control signal T5 corresponding to the armature radio wave called is determined, and TS and Te are sequentially output. If the vehicle speed continues to decrease, step P22゜P361 Pto
, P mouth , P, 2 , P・t:+ , P
24, P25.

Passing through P 2b + P2□, T,,T,
Increase the correction, and if it reaches the determined value, stay, bu P1 □
Then jump to resteps P2 and 3 and return to the low speed stable area. Therefore, even if the vehicle speed exceeds a predetermined value and falls below the predetermined value before the reduction correction is completed, the reduction correction value A is stored, and the increase correction is performed from that state. On the other hand, even if the vehicle speed becomes equal to or higher than the predetermined value after the vehicle speed becomes less than a predetermined value and the increase correction control is started, the increase correction value A is stored and the decrease correction is performed from this state. I can do it.

Therefore, in this case, the relationship between armature current Ia, clutch current Ic, and time t is as shown from time t=13 to 1=14 in FIG.
If the decrease exceeds , the electric motor (3
Corresponding to the auxiliary torque of 3), the transmission torque of the electromagnetic clutch (63) gradually increases until it reaches the determined value, thereby improving the steering feeling and stability. Furthermore, power consumption can be reduced as in the case of increasing vehicle speed.

As described above, in this embodiment, since the transmission torque of the electromagnetic clutch is controlled over time in response to changes in vehicle speed, it is possible to improve the steering feeling and steering stability. In addition, power consumption can be reduced by controlling the transmission torque of the electromagnetic clutch over time, and there is no need to provide hysteresis in the predetermined value for comparing the vehicle speed V, as in this embodiment, and the vehicle speed V is always stable at the predetermined value. It can be operated by

(Effect of the invention) According to the present invention, as is clear from the above description.

When steering torque is applied, when the vehicle speed increases beyond a predetermined value, the transmission torque of the clutch means is reduced over time, and when the vehicle speed decreases beyond a predetermined value, the transmission torque of the clutch means is reduced over time. By increasing the torque over time to a determined value, it is possible to reduce power consumption, and also to smoothly stop the electric power steering device when the vehicle speed changes from low to high speed and return to manual steering, and conversely when changing from high speed to low speed. It exhibits a smooth connection with no sudden changes when moving from manual steering to electric power steering, and it maintains a continuous flow even when the vehicle speed changes vibrationally around a predetermined value. Therefore, the stop and operation of the electric power steering device can be controlled stably and smoothly while the vehicle speed is always at a predetermined value.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention, and FIGS. 2 to 14 relate to an embodiment of the electric power steering device of the present invention.
Figure 2 is a longitudinal sectional view showing the electromagnetic booster bent at a 90° cut plane, Figure 3 is a sectional view taken along the ■-■ arrow in Figure 2, and Figure 4 (a) is a cross-sectional view taken along the ff-IV arrow sectional view in Figure 2, No. 4
Figures (b) and (c) are a plan view and a side view of the movable iron piece, Figure 5 is a sectional view taken along the v-v arrow in Figure 2, and Figure 6 is a cross-sectional view of the movable iron piece.
7 is an overall configuration diagram of the control device, FIG. 8 is a flowchart showing an outline of control processing, and FIG. 9 is a diagram showing the relationship between steering torque and tm current. Figure 10 is a diagram showing the relationship between steering rotation speed and motor rotation speed, Figure 11 is a diagram showing the relationship between armature current and clutch current, and Figure 12 is a diagram showing the relationship between clutch current and time. FIG. 13 is a pulse waveform diagram showing the steering rotational speed signal, and FIG. 14 is a diagram showing the relationship between the steering torque and its detection signal. In the drawing, 63...Electric clutch (clutch means) 77...
... Steering torque detection means 86 ... Vehicle speed detection means 108 ... Clutch drive means S,, S, ... Steering torque detection signal S3 ...
...Steering speed detection signal S4...Vehicle speed detection signal T4...Clutch control l@Gokenkoro ll111 Kano - Prefecture - Kawaichiri
Private room
Takotsu Sakura

Claims (1)

[Claims] an electric motor that generates an auxiliary torque corresponding to the steering torque of the steering system; a clutch means that connects and separates the electric motor from the steering system; and a clutch means that detects the steering torque of the steering system based on a detection signal from the steering torque detection means that detects the steering torque of the steering system. An electric power steering device comprising: a clutch control signal generating means for determining a transmission torque of a vehicle and outputting a clutch control signal; and a clutch driving means for driving the clutch means in accordance with the control signal; and vehicle speed determining means for determining whether the vehicle speed has increased or decreased from a predetermined value based on the detection signal from the vehicle speed detecting means, and a vehicle speed increasing beyond the predetermined value based on the output signal from the vehicle speed determining means. correction means for correcting the clutch control signal so as to reduce the transmission torque of the clutch means over time when the vehicle speed decreases beyond a predetermined value, and increase the transmission torque of the clutch means over time to the determined value when the vehicle speed decreases beyond a predetermined value; An electric power steering device comprising: