JPS62181958A - Power-driven type power steering device - Google Patents

Abstract

PURPOSE:To increase the extent of steering force in a steering wheel slowly, and secure such a favorable steering feeling that enjoys a high-grade feeling even at the time of stoppage, by not eliminating motor auxiliary torque but decreasing it by degrees at the time of a controller being stopped. CONSTITUTION:In this system there are provided with a steering state detecting device 60 constituted of a steering detection means 1 in a steering system and a steering rotation detecting means 2, a motor control signal generating device based on this detection signal and a motor driving means 4 based on this signal. And, also there are provided with a trouble diagnostic means 5 of switches 8 and 9, an operation stop detecting means 6 for the device itself and a compensating means gradually reducing a motor control signal with this detection signal. Thus, at times of these switches 8 and 9 being off and outputting a stop signal out of the trouble diagnostic means 5, the operation stop detecting means 6 detects it, and with this detection signal, the compensating means 7 decreases the motor control signal along with time, outputting it to the motor driving means 4, whereby an electric motor is stopped slowly. Therefore, steering force is gradually increased, so that a steering feeling can be made so favorably even at the time of operation stopping.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electric power steering device that reduces steering force by generating auxiliary torque using an electromagnetic booster using an electric motor, and particularly relates to This invention relates to improving control when equipment is stopped.

(Prior Art) Generally, an electric power steering device includes an electromagnetic booster using an electric motor as a torque generation source and a control device thereof, and detects at least a steering state such as a steering torque applied to a steering wheel. Based on this detection signal, the electric motor generates auxiliary torque to reduce the steering force.

(Problems to be Solved by the Invention) Such an electric power steering device is used when a stop signal is generated when the key switch of the vehicle is turned from an on state to an off state, or from a fault diagnosis circuit that detects a fault in a control device. If this occurs, the electric motor for generating auxiliary torque and the electromagnetic clutch that connects and disconnects the transmission of this generated torque are immediately disconnected to stop electric motor control, and as a result, the steering torque suddenly increases and the steering wheel There was a risk that this would not only spoil the sense of luxury, but also significantly reduce the steering feel, especially during steering.

(Purpose of starting/-) Therefore, 1. When the key switch is turned off or when the electric power steering device is stopped by the control device itself, the motor control signal for controlling the drive of the electric motor is gradually reduced over time. As a result, the steering force on the steering wheel is gradually increased and the operation is stopped.
In addition, in devices equipped with an electromagnetic clutch, by disengaging the electromagnetic clutch after stopping the operation of the electric motor, when the device is stopped, the steering wheel steering force is prevented from increasing rapidly and is made gentler. The purpose of the present invention is to provide an electric power steering device that improves the feeling of steering.

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

As shown in the figure, the device of the present invention includes a steering state detecting means comprising a steering torque detecting means (1) for detecting the steering torque of the steering system and a steering rotation detecting means (2) for detecting the steering rotation speed. (80).

Motor control signal generation means (3) that determines and outputs a motor control signal based on the detection signal from this detection means (60)
, a motor drive means (4) for driving the motor based on a motor control signal, and further includes switches such as a key switch (8, 9), a device failure diagnosis means (5), and detects the stoppage F of the device itself. an operation stop detection means (6), and a correction means (for gradually decreasing the Jingji motor control signal over time based on the detection signal from the operation stop 1 detection means (6));
7), and when the switches (8, 9) that stop the operation of the device itself are turned off, or when a stop signal is output from the fault diagnosis means (5), the device is stopped by these signals. The operation stop detection means (6) detects that the motor is out of operation, and based on the detection signal from the detection means (8), the correction means (7) decreases the motor side U4 signal over time, and the motor drive means (4) ) to gently stop the motor. Therefore, when the device itself stops operating, the steering force of the steering wheel does not increase suddenly but gradually increases, and the steering feeling when the device itself stops operating becomes good.

(Example) An embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 2 is a schematic cross-sectional view showing the electromagnetic booster bent at 80 degrees.

According to the figure, the electromagnetic booster that constitutes the electric power steering device is configured via a rack shaft (21). That is, the right side of the rack shaft (21) is equipped with an input shaft (26) connected to a steering wheel (not shown), a steering torque sensor (35), and a steering rotation sensor (40). An electric motor (11) that generates auxiliary torque is installed on the left side of the motor. These will be explained below.

The rack shaft (21) has a pinion gear (22) on its right side.
are engaged with each other to form a rack-and-binion mechanism. The pinion gear (22) is rotatably supported at both ends by angular contact bearings (23) and (24).

Further, an input shaft (2B) is connected to the upper side of the pinion gear (22) in the drawing via a torsion bar (27). The input shaft (26) is connected to the pinion shaft (22a) via a bearing (28) and is rotatable relative to the pinion shaft (22a). The pinion shaft (22a) has two claws (22b) each having a generally fan-shaped cross section projecting from each other at 180 degrees apart. This pawl (22b) is bored at a corresponding position on the input shaft (2B), and has a complementary shape groove (28).
Fit into a) with an appropriate gap. Therefore, the input shaft (2B) and the pinion shaft (22a) can rotate relative to each other by a predetermined angle, and when the angle is exceeded, they rotate together as one unit.

The steering torque sensor (35) has a slider (29) and a differential coil (31) as main components. Slider (2
9) is made of a cylindrical member and is slidably fitted onto the input shaft (2B) and the pinion shaft (22a). This slider (
On the side surface of the groove (29), there are grooves (29a), (29a) parallel to the axial direction spaced apart by 180 degrees from each other, and grooves (2,9a).
), (29a) and grooves (29b) formed at positions rotated by SO degrees and bored diagonally with respect to the axial direction. On the other hand.

The protrusion (22
b), (22b) have pins (30a), (30
a) are provided in one piece and fit into the parallel grooves (29a) and (29a) of the slider (29). In addition, the grooves (28a), (2ea) of the input shaft (26) having a substantially fan-shaped cross section, the protrusions (28b), (28b) formed by
30b) and (30b) are provided in one piece, and fit into the diagonal grooves (29b) and (29b) of the slider (29). Therefore, the input shaft (26) and the pinion shaft (22a)
The relative rotation of is converted into an axial displacement of the slider (29). At this time, due to the effect of torsion/<-(27), the axial displacement of the slider (28) and the steering torque become proportional. Therefore, the primary winding 5ji (31a) and the secondary winding (3
A differential coil (31) consisting of 1b) and 31c is provided. - The secondary winding (31a) is supplied with an AC signal from the control device (32) to excite the secondary windings (31b) and (31c) via the slider (29) to change the inductance. Therefore, the alternating current voltage changes differentially in the secondary windings (31b) and (31c) according to the displacement of the slider (29).

The steering rotation sensor (40) includes a gear (3B) that rotates together with the input shaft (26), a gear (37) that transmits the rotation of this gear (3B), and a generator (37) that is driven by the rotation of this gear (37). 38). The gear (3B) is
It is coaxially fixed to the input shaft (26) between the steering torque sensor (35) and a bearing (34) that supports the input shaft (28).

A flange member (41) is attached above the bearing (34) to prevent dirt from entering the case (33). The gear (37) is fixed to the rotating shaft of the generator (3rd) and meshes with the gear (36).

The generator (38) thus has gears (3B),
(3?) are fixed to the outside of the case (33) so that they interlock with each other. The generator (38) is generally a DC machine. According to such a configuration, the gear (36) rotates as the steering wheel (not shown) rotates, which causes the generator (38) to rotate and generate a predetermined voltage signal (S2). The rotation speed and rotation direction of the steering wheel can be detected from the output voltage value of the generator (38) and its polarity.

A pole screw (42) is cut on the left side of the rack shaft (21), and forms a pole mechanism together with a pole nut (43) that is attached via a pole (45). Oil seals (43a) are installed at both ends of the pole (43).

43a) is provided. Also, Ball Nala) (43)
An annular protrusion (43b) is integrally formed on the outer periphery of the pulley, and acts as a pulley. This pulley (43b
Angular contact bearings (4B) and (47) fixed to the case (33) are mounted on both sides of the rack shaft (21) in the axial direction, and convert the rack shaft (21) into linear motion.

The electric motor (11) is arranged above the pole nut (43). A pulley (53) having a smaller diameter than the pulley (43b) is fixed to the rotating shaft of the electric motor a (11) via a key and a nut (both not shown). These two pulleys (43b) and (53) are interconnected by a cog belt (54) and transmit the rotational torque of the electric motor (11) to the pole nut (43). Due to the rotation of the pole rack (43), the rack shaft (21) is displaced in the axial direction, and the electric motor (1
The auxiliary torque of 1) will be transmitted to the rack shaft (21). The electric motor (11) has an electromagnetic clutch (18) in its casing, and the electric motor (11) and the pulley (53) are connected or disconnected by an output command signal from the control device (32). be done.

Next, the control device will be explained based on FIG.

The control device (32) includes a steering torque/interface circuit (Cl0A), a steering rotation/interface circuit (I
OB), A/D converter circuit (IOC), microcomputer unit) (100), motor drive circuit (motor drive means) (4), clutch drive circuit (12
), a power supply circuit (13), a current detection circuit (19), etc., and the steering torque detection means (1) shown in FIG.
The reference clock pulse TI of the steering torque sensor (35) and the microcomputer (22) (100) is frequency-divided, converted into an AC signal, and supplied to the primary winding of the differential transformer. It is comprised of a steering torque interface circuit (IOA) that rectifies and smoothes the output from the next winding, and outputs a steering torque detection signal Sl that indicates the direction and magnitude of the steering torque. Further, the steering rotation detection means (2) in FIG. 1 converts the outputs from the steering rotation sensor (40) and the DC generator (38) of the steering rotation sensor (4o) into absolute values according to the polarity. It is composed of a steering rotation/interface (IOB) that amplifies the steering rotation direction and outputs a steering rotation detection signal S2 indicating the steering rotation direction and steering speed of the steering system. In addition, the above-mentioned steering torque detection means (
1) and the steering rotation detection means (2) constitute a steering state detection means (60).

Microcomputer Units) (100) HaI10
Consists of ports, memory, arithmetic unit, control unit, registers, clock generator, backup power supply, etc.
Operates based on clock pulses.

The power supply circuit (13) that drives the microcomputer unit (100), etc. is a relay circuit ( 17) and a constant voltage circuit (
18). Therefore, the key switch (
8) When input, the microcomputer uni...
) (100) detects each detection signal S1 to S3 based on the command.
is digitally converted by an A/D converter circuit (IOC), and a detection signal S4 indicating the on/off state of the key switch (8) is processed according to a program stored in the memory to control the electromagnetic clutch (1B). The signal T5 is output to the franchise drive circuit (12), and the electric motor (11
) are outputted to the motor drive circuit (4) to drive and control the motor (11).

The motor drive circuit (4) includes a bridge circuit consisting of FETs (field effect transistors) and control signals T3. It is composed of an interface circuit that drives a bridge circuit by T4, and controls the rotational direction and power of the electric motor (11) by PWM drive. Further, the TL magnetic clutch drive circuit 12) controls engagement and engagement of the electromagnetic clutch (1B) using a clutch control signal T5.

In addition, the microcomputer 22) (100) d generates a motor control signal generating means (3), an operating floating surface detecting means (
B), a correction means (7), and a failure diagnosis means (5).

The electric motor control signal generating means (3) receives a detection signal S from the steering torque detecting means (1) and the steering rotation detecting means (2).
1.52, the duty ratio of the control signal is determined and outputted so that the PWM-controlled electric motor (11) can generate the necessary auxiliary torque. For example, this electric motor control signal T3. T4 is obtained by calling a predetermined duty ratio stored in a table using the signals St and S2 as address signals.

The failure diagnosis means (5) is a microcomputer (100
), and for example, at the start of control, the microcomputer (100) sends a pseudo signal to the steering torque detection means (1), the steering rotation detection means (2), and the motor control signal generation means (3). Diagnose whether normal control is possible. In addition, this failure supply/disconnection means (5)
constantly monitors the current flowing through the motor drive circuit (4) via the current detection circuit (19) to detect abnormalities.

Furthermore, by turning on the key switch (8), the constant voltage circuit (18) is connected to the power source (14) such as the vehicle battery.
Current is supplied to each component of the control system via the relay circuit (17) and the like, and the fault diagnosis means (5) supplies current to the constant voltage circuit (18) based on the ON signal of the key switch (8). Whether the supply voltage of the relay circuit (
17) is normal<:? Diagnose whether it is working.

The relay circuit (17) detects that the key switch (15) has been turned on via a microcomputer (IOD).
) is excited by the detection, and the contact self-holds to maintain the on state.

When the fault diagnosis means (5) diagnoses a fault through such a check, it generates a fault detection signal, that is, an operation stop signal.

The operational levitation detection means (8) detects a failure detection signal from the failure diagnosis means (5), an OFF signal from a key switch (8), an OFF signal from an external switch (9) such as a manual switch, etc., as an operational stop state. For example, the inoperation detection means (6), which performs detection processing by comparing the contents of the flag register of the microcomputer (100) with a predetermined logical value, detects these inoperation states. When detected, a stop control command signal is sent to the correction means (7).

When the stop control command is input, the correction means (7) does not immediately reduce the current duty ratio calculated by the motor control signal generation means (3) to zero.

Calculation control is performed to gradually decrease the duty ratio.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG. In the following explanation, the symbols PO to P24 indicate each step in the flowchart, and Pl4
Codes such as -Y and Pl4-N indicate that the decision blocks are positive and negative, respectively.

First, when the key switch (8) is turned on, the control system starts and the microcomputer unit (PO) and microcomputer unit (
Clear the various registers in the microcomputer unit (100D), set the initial values (Pl), and set the arbitrary number C to 1.0 Next, check for initial failures such as whether the microcomputer unit (100) itself is normal. To execute the diagnosis (P2), send the electromagnetic clutch control signal T5 to the electromagnetic clutch (IB) to turn it on (PG). After that, the steering torque detection means (1) reads the detection signal Sl (P4) and calculates the steering torque (P5).
) is normal (PG), then similarly, the steering rotation detection means (2) reads the detection signal S2 (Pl) and calculates the steering rotation (P8),
A failure diagnosis is performed to determine whether the steering rotation detection means (2) is normal (PO). Next, a detection signal S4 indicating an operation stop state (off state) is output from the key switch (8).
and process the corresponding flag (PIO, pH
). For example, when the key switch (8) is turned off and the device is in a non-operational state, the contents of the corresponding flag register (not shown) are set to 1. Then, in the electric motor control signal generating means (3), the rotation direction N of the electric motor 4!1 (11) and the duty ratio of the control signal are determined (Pl
2. Pl3).

After this, the flag register is scanned and the fault diagnosis means (5)
, the key switch (8), and the external switch (9), the operation stop detection means (8) checks whether the operation stop state is occurring (Pl4). If the operation stop signal is not generated, (Pl4-N), the rotation direction signal N and the duty ratio signal are sent out. At this time, the current flowing through the motor (11) is read by the current detection circuit (19) (Pl7), and a fault diagnosis is executed based on this (Pl8). After this fault diagnosis (PlB), the process returns to step P4, and the above Execute a motor control cycle similar to that described in .

On the other hand, if a shutdown condition occurs (
Pl4-Y), the operation stop detection means (6) is the correction means (
7) Sends a command signal to The correction means (7) then executes an operation D*C of multiplying the duty ratio signal given by the motor control signal generation means (3) by a variable C, and uses this operation value as a new duty value. (Pl9
), this variable C is a value that gradually decreases from 1, and C=O does not become true until the electric motor (11) stops. After this duty value change calculation, it is determined whether C is larger or smaller than O. (P2O). As a result, if C≧0, the operation c −o,ot which decreases the value of variable C by 0.01
, and then returns to the normal motor control cycle in step P, 15. In the case of deactivation, the control cycle is repeated unless the flag to that effect is reset. Then, each time this turning green, step P20
, P21, the variable C gradually decreases by 0.01, and the duty value also decreases. Therefore, when the stopped state of the electric power steering device itself is detected, the motor control signal T4 changes. The correction is gradually reduced, and the steering force of the steering wheel is gradually increased.

Finally, the value of variable C becomes 0 or a negative value (
P2O-Y), the electromagnetic clutch (16) and the relay circuit (14) are sequentially turned off (P22, P23),
Control is stopped (P24). As a result, the steering force increases gently when the operation is stopped, so that a good steering feeling can be achieved.

In addition, if a temporary misdiagnosis is made due to external noise etc. in each fault diagnosis step (PG, PO, Pl8) (for example, diagnosing a fault even though it is not a fault), instead of stopping the control immediately, multiple times (in the example, 1
00 times), and during which further failure diagnosis is performed, it is possible to return to normal control from the point at which the erroneous diagnosis is completed, and it is possible to improve resistance to external noise and the like.

(Effects of the Invention) According to the present invention, as described above, the auxiliary torque of the electric motor is not immediately removed when the control device is stopped, but is gradually reduced, thereby gently increasing the steering force of the steering wheel. This makes it possible to obtain a high-quality and good steering feeling even when the vehicle is stopped.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Figs. 2 to 4 show an electric power steering device according to an embodiment of the present invention, and Fig. 2 shows an electromagnetic booster bent at 90 degrees. The sectional view shown in FIG. 3 is the control i11? Block configuration diagram of
FIG. 4 is a flowchart showing an outline of the control process. In the drawings, (1) is a steering torque detection means, (2) is a steering rotation detection means, and (3) is an electric motor-control signal generation means. (4) is a motor drive means, (5) is a fault diagnosis means, (8
) is an operation stop detection means, (7) is a correction means, (11) is an electric motor, and (80) is a steering state detection means.

Claims (1)

[Claims] Steering state detection means for detecting the steering state of the steering system; motor control signal generation means for determining and outputting a motor control signal based on the steering state detection signal from the steering state detection means; An electric power steering device comprising: an electric motor drive means for driving the electric motor based on a motor control signal; an operation stop detection means for detecting an operation stop of the device itself; An electric power steering device comprising: a correction means for gradually decreasing the electric motor control signal over time.