JPS62199566A - Neutral position resetting device for steering gear - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a steering device that automatically returns the steering system to the intermediate position using the power of an electric motor when the steering system is desired to return to the intermediate position. This invention relates to an intermediate position return device.

(Prior Art) A steering device converts the rotation of the steering wheel into a rocking motion of the wheels to enable steering of the vehicle.While the vehicle is running, the rotation of the steering wheel causes the vehicle to be steered. It has a characteristic that the device itself tends to return to the intermediate position by means of caster trails and the like. Therefore, generally, when the steering wheel is released or the steering force is weakened, the steering wheel (steering system) is returned to the intermediate position.

(Problem to be Solved by the Invention) However, in the conventional steering device described above, when the vehicle is stopped, there is no force to return the steering wheel to the middle position, so even when parking on a narrow road or in a bad garage environment, It may be difficult to park the vehicle in a garage, and it requires considerable driving experience to be able to park the vehicle in a straight line. Furthermore, even when the vehicle starts from a state where the steering wheel has not returned to the middle position, it may be difficult to start the vehicle smoothly on a narrow road or in a bad garage environment.

(Purpose of the Invention) Therefore, the present invention enables smooth stopping and starting even on narrow roads or garages with poor garage environments by automatically returning the steering device to the middle position when the steering device is desired to return to the middle position. An object of the present invention is to provide an intermediate position return device for a steering device that can be expected to perform a smooth return operation regardless of the size of the steering device.

(Means for Solving Problems and Their Effects) The intermediate position return device of the present invention comprises a position detection means for detecting the steering position of a steering system, a rotation detection means for detecting the rotational speed of an electric motor, a switch means, and a drive control device for the electric motor. The motor control means determines and outputs a motor control signal for driving and controlling the motor based on the output signal from the position detecting means when the switch means is turned on. At the same time, the steering system is returned to the neutral position by controlling the drive of the electric motor based on the bias between the electric motor control signal and the output signal from the rotation detecting means. Therefore, regardless of the magnitude of the load on the road surface, it is possible to return the steering system to the intermediate position t at any set return speed, thereby making the return operation smooth.

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

FIG. 1(a) is a schematic vertical cross-sectional view of a steering device equipped with the intermediate position return device of this embodiment, FIG. 1(b) is a plan view of a potentiometer, FIG. 2 is a control device thereof, and FIG. indicates the control process.

In Fig. 1(a), (1) is the steering shaft;
A steering wheel is fixed above the steering shaft (1) in the figure via a first universal joint, a first shaft, a second universal joint, and a second shaft (not shown). The steering shaft (1) is rotated with axial play removed by angular contact bearings (4A) and (4B) that are pressed against the cap (2a) of the case (2) via a disc spring (3). It is freely supported. In addition, the steering axis (
A seal member (5A) and a dust seal (5B) are provided at the opening of the case (2) in 1). Furthermore, the steering shaft (1) is provided with a single pinion gear (1a), and this pinion gear (1a) is provided with a rack shaft (
The rack (6a) of the shaft-like member) (θ) is in mesh with each other, converting rotation of the steering shaft (1) into linear motion of the rack shaft (6). In addition, tie rods and knuckles (not shown) are connected to both ends of the rack shaft (6), respectively, so that the swinging motion of the wheels can be converted to allow the steering of the vehicle.

Further, a small-diameter toothed pulley (1b) is pivotally attached to the other end of the steering shaft (1). Correspondingly, a potentiometer (7) is fixed to the case (2) approximately parallel to the steering shaft (1), and this potentiometer (
At the end of the shaft that rotates the contact piece (1 day) of 7), there is a mark shown in Figure 1 (
As shown in b), a large-diameter toothed pulley (7a) is pivoted, and this large-diameter pulley (7a) and the small-diameter pulley (
A timing belt (7b) is wound between the timing belt (7b) and the timing belt (7b). Therefore, the rotation of the steering shaft (1) is decelerated and transmitted to the potentiometer (7), and the rotation angle of the steering shaft (1) is converted into a resistance value of the potentiometer (7). This potentiometer (7
) constitutes an intermediate position sensor.

A pole screw (8) is provided at the left end of the rack shaft (8) in FIG. 1(a). This pole screw (8) is
a spiral groove (6b) formed on the outer circumferential surface of the rack shaft (8); a nut portion (8a) having a spiral groove (8b) on the inner circumferential surface and spiraled around the outer circumference of the spiral groove (6b); Spiral groove (6b)
and a plurality of poles (8c) encircled by (8b). In addition, the nut part (8a) is rotatably supported by the case (2) with angular contact bearings (9A) and (9B) pressed through disc springs to eliminate play in the axial direction, and has a large diameter on the outer periphery. It is integrally equipped with a toothed pulley (8d). The case (
2), an electric motor (9) is fixed approximately parallel to the rack shaft (8), and a small-diameter toothed pulley (
A timing belt (11) is wound between the small diameter pulley (9a) and the large diameter pulley (8d). Therefore, the rotation of the electric motor (8) is rotationally transmitted to the nut member (8a) of the bolt screw (8) via the timing belt (11), and this pole screw (
8) into a linear motion of the rack shaft (8). Note that (12, 12) in the figure is a sealing member.

Further, a DC generator (tachogenerator) (13) is connected to the rotating shaft of the electric motor (8). Further, a manual switch (20) is provided near the steering wheel. And these potentiometers (7)
, electric motor (8), switch (20) and electric motor (13
) is electrically connected to the control trace W1 (10).

Next, the m control device (lO) will be explained.

In Fig. 2, intermediate position detection means (position detection means')
(1B) consists of a potentiometer (7), a low-pass filter (23), and an operational amplifier (25).The potentiometer (7) consists of a resistor (17) and a contact piece (18), and one end of the resistor (17) The other end is connected to a constant voltage power supply A of a constant voltage circuit (4B) to be described later through a resistor (21), and the other end is connected to the common side (earth) through a resistor (22). The contact piece (18) is input to a low-pass filter (23), and this circuit (23) removes noise caused by movement of the contact portion between the contact piece (18) and the resistor (17). The output of the low-pass filter (23) is connected to the inverting terminal of the operational amplifier (25) via the resistor (20).The voltage of power supply A is connected to the non-inverting terminal of the operational amplifier (25) through the resistor (20)
6) and (27), the voltage is divided into the station and input through the resistor (28), and the divided voltage is directly input to the A/D.
It is input to the converter (29) and becomes the reference voltage S3.

A negative feedback circuit is formed by a resistor (30) connected between the inverting terminal of the operational amplifier (25) and the output terminal of the operational amplifier (25), and the output of the operational amplifier (25) is input to the A/D converter (29). The intermediate position detection signal S7 is output. The output of the A/D converter (29) is connected to the I10 port of the microcomputer unit (32), and the detection signal of the 1st position is read based on the control described later.

The switch means (1B) includes a manual switch (20) installed near the steering wheel, a low-pass filter (
34) and a waveform shaping circuit (35). One end of the switch (20) is connected to the common side (ground), and the other end is connected to the constant voltage power supply A via a resistor (33).
The low-pass filter (30) removes noise accompanying the opening and closing of the switch (20), and the output of the low-pass filter (30) is connected to the waveform shaping circuit (35). It is connected to the I10 port of the microcomputer unit (32) through the waveform shaping circuit (35), and is shaped into a rectangular wave and output as the output signal St when the switch is turned on.
The signal S at the time of input (20) is read based on the control described later.

Microcomputer unit (32) 4*CPU,
! Standard lock, clock generator, ROM, R
A.M.

It is composed of an I10 port, etc., and operates according to a ROM in which control software, which will be described later, is written. A motor drive means (40, which will be described later) is connected to the output side of the microcomputer unit (32) via an El/A converter (3B).
) In (32), the motor control signal 'r3. 'r, (T3: direction control signal, T
4: Rotation speed control signal) is determined and output. Among the control signals, T3 is sent to the drive unit (43) of the motor drive means (44), and T4 is sent to the above-mentioned port/A converter (3).
B) is output to the (+) input terminal of the differential amplifier circuit (40). Furthermore, microcomputer unit (32)
, A/D converter (29) and D/A converter (3B) constitute motor control signal generating means (37).

In FIG. 2, (38) is a rotation detection means, and this rotation detection means (38) is composed of the generator (13) and an absolute value amplification circuit (39) that amplifies the absolute value of the output voltage. , Therefore, a detection signal S4 corresponding to the rotational speed of the electric motor (9) is obtained from the absolute value amplification circuit (38),
It is input to the (-) input terminal of a differential amplifier circuit (40), which will be described later.

The motor drive means (44) is composed of a differential amplifier circuit (40), a triangular wave generation circuit (41), a comparator circuit (42), a drive unit (43), and a bridge circuit consisting of an FET Ql''Q4. ing.

The differential amplifier circuit (40) calculates and outputs a deviation ΔC between the rotational speed control signal T4 and the rotational speed detection signal 54 of the electric motor (9). Therefore, the differential amplifier circuit (40) outputs the difference ΔC between the motor control signal T4 and the current rotational speed of the motor (9). The output ΔC of this differential amplifier circuit (40) is input to the (+) input terminal of a comparison circuit (42), and the triangular wave generation circuit (41) is connected to the (-) input terminal of this comparison circuit (42). ing. Therefore, in the comparison circuit (42), the differential amplifier circuit (42)
The level of the deviation output ΔC from 0) with respect to the triangular wave is compared and outputted to the drive unit (43) as a PWM signal C with a duty ratio corresponding to the deviation output ΔC.

The drive unit (43) includes FET Q+, Q
FE by the booster circuit for driving 4 and the control signal T3 from the microcomputer unit (32).
It consists of TQl+Q3 or FETQ2, a circuit that enables operation by switching the Q signal, etc. Drive Uni/
) (36) is output from FETQ1. The FET Q+ is connected to each gate terminal of the FET Q4, and the drain terminals of each of the FETs Q+ and Q4 are connected to the positive side of the battery (45). The source terminals of FET Q, , Q4 and the drain terminals of FET Q2 and Q3 are connected respectively, and the connection between the source terminal of FET Q4 and the drain terminal of FET Q3 is connected to the source terminal of FET Q and the drain terminal of FET Q3.
The connection portion of the drain terminal of TQ is connected to the motor (9).The drain terminals of each of the a FETs Q 2 *Q 3 are connected to the common side.

In addition, the positive terminal of the battery (45) is connected to a constant voltage circuit (
46) is connected. The output A of this constant voltage circuit (46) is a constant voltage lower than the battery voltage (45),
The signal is supplied to control circuits such as low-pass filters (23), (34), a waveform shaping circuit (35), an operational amplifier (25), and a microcomputer (32). The motor control signal generating means (37) and the motor driving means (44) constitute a motor control means.

In this embodiment, control processing 41 of the microcomputer unit is performed according to the flowchart shown in FIG.

Note that PI'''P21m in FIG. 3 indicates each step.

First, when the power is turned on, control is started, and in step P, the registers in the CPU and the data in the RAM are cleared. In step P2, the output signal S1 of the switch (20) is read. Here, the switch (20) is turned off.
When the switch (20) is turned off, sl becomes O, and when the switch (20) is turned off, sl becomes almost equal to the output voltage A of the constant voltage circuit (45) and becomes rlJ.In step P3, the switch (2o) Determine whether the output signal S is "0", that is, ON, and if it is OFF, S
, = 1, it jumps to step P2 and waits for input of the output signal from switch (2o).

If the switch (20) is ON, S,=Q, so the process proceeds to step P4, reads the detection signal S7 of the intermediate position detection means (1B), and then inputs the reference voltage S3 in step P5. At this time, the detection signal S2 and reference voltage S3 are expressed as shown in FIG. In step P, the difference between Sl and 83 is processed to be S, and the amount and direction of deviation from the middle position of the steering device are calculated and stored in the S register. In step P7, it is determined whether the value of the S register is 0, and if it is 0, the process proceeds to step PII, where the direction control signal T3 consisting of R=L=0 is output to the motor drive means (40), and the direction control signal T3 consisting of R=L=0 is output to the motor drive means (44). ) FETs (Qt~Q4) are all O
FF. Then, in step P9, the value of the duty D, which is the rotational speed control signal T4, is set to O and is output to the motor drive means (44) through the D/A converter (36). Then jump to step P2.

Waits for switch input.

If the value of the S register is positive or negative, step P
The code is determined by IG. If the value in the S register is negative, in step PI2, R is set to 0 and L is set to 1, and in step PIG, the value in the S register is sign-converted S←
-5, the process proceeds to step P14. If the value in the S register is positive, R is set to 1 and L is set to 0 at step pH.

In step Pi4, an operation SA is performed to provide a dead zone A in the value in the S register, and the subsequent value is stored as S in the S register. And step P Is
Then, the sign of the value S in the S register is determined. If negative,
Since it is within the dead zone A, it is determined that the position is in the middle position, and the process jumps to step P8 to stop the operation of the motor drive means (44).

On the other hand, if the value of S is positive, it is larger than the value of dead zone A, and therefore it is necessary to return to the middle position. Therefore, the process advances to step Plea, and the -N value is read out to the data whose address is S in the S register. That is, the ROM is configured with a table storing the data shown in FIG. 5, and this table includes the detection signals 52-3. Data that determines the rotational speed of the motor (9) is stored in the ROM whose address is the absolute value of N.
The armature voltage V corresponding to the duty value obtained by binary-coding the value obtained by dividing the product of and by the battery voltage ■ is stored. Therefore, this duty value determines the rotational speed of the rotating machine of the electric motor. In step P16, the data in the ROM whose address is the data in the S register, that is, the speed duty, that is, the -N value, is called, and in step P17, the read-out -N value is set as the control duty value D. Store in register. Then, in step p+a, the direction control signal T3 consisting of R and L is output to the drive unit (43) of the motor drive machine (44), and in step P19, the rotation is made according to the control duty value in the D register. The speed control signal T4 is output to the D/A converter (36), and the D/A converter (36) outputs T4 as an analog signal to the differential amplifier (40). And the microcomputer unit (32)
In this case, this process is repeated until the detection signal 5=S2-S3 from the intermediate position detection means (IB) enters the insensitive body A.

Furthermore, the differential amplifier circuit (40) of the motor drive means (44)
), the torque signal T4 converted into an analog signal by the D/A converter (38) and the rotation detection means (
The deviation ΔC from the detection signal S4 detected by 38) is output. This deviation output ΔC is the deviation between the set rotational speed requested of the electric motor m (9) and the actual rotational speed of the electric motor. Then, this deviation output ΔC is calculated by the comparison circuit (
42), it is output as PIIIM signal C to the drive unit) (43). Drama Eve Unit) (4
In 3), the electric motor (9) is driven by driving the FETs Q+ to Q4 using the direction control signal T3 and the PWM@C of the deviation output ΔC, which causes the steering system to operate at the set rotational speed. Returned to mid position.

Therefore, in this embodiment, as shown in FIG. 5, the return speed can be arbitrarily set to a constant value up to the vicinity of the middle position, or to a return speed that gradually decreases from the vicinity of the middle position to the middle position. , P-M signal C that drives and controls the electric motor (9)
is formed by the deviation ΔC from the rotational speed of the electric motor (8), so the steering system can be reset at any set speed regardless of the magnitude of the road load, and a smooth differential can be expected. Further, since the PWM signal for driving and controlling the electric motor (9) is obtained from the deviation from the rotational speed of the electric motor (9), there is an advantage that response performance is improved.

Next, regarding the control processing according to another embodiment of the present invention, steps P P +a to P 32 that are different from the previous embodiment will be explained.

In this embodiment, the electric motor (9) for returning the steering system to the intermediate position is controlled as shown in FIG. In this example, the speed is controlled to be constant and gradually decrease in the range a near the middle position.

In FIG. 6, in step PIs, 5-(a+C) is calculated and this is designated as b. a and C are constants consisting of integers arbitrarily set by initial setting.0 Next, in step PI5, it is determined whether b>o, and b>0.
If not, it is determined that the displacement from the intermediate position is within dead zone A, and the process proceeds to step P8, where the electric motor (9) is not driven.

If b>o, the process proceeds to step P18, where it is determined whether c=0, and if c=0, steps P17 to P
2+ processing is performed. In step P17, C is decremented one by one. In step P Ill, a direction control signal T3 consisting of R and L is output. In step PI9, a rotation speed control signal T4 consisting of control duty D is output. Then, step P2O-11-D is incremented one by one, and this process is repeated at the repetition period set in step P21 until c=0. Therefore, in the range of C as shown in FIG. The torque of the electric motor (9) increases, and the return speed of the steering system increases.

Next, if C is zero at step P1θ, the process proceeds to step P22, where it is determined whether b=o. b
If not =o, perform steps P21 to F21m. In step Pi11, b is decremented one by one, and the previous step P II + P 19 + P21
Processing similar to that is performed in steps P24 to Ps,
This is repeated until b=o. Therefore, in the range b, the return speed is constant as shown in FIG.

Further, if b is zero in step P22, step P
The process proceeds to step 27, where it is determined whether a=0.

If a=O is not true, steps P2@ to pa2 are performed. In step P2B, a is decremented by one, and the same processing as in the previous steps PI8 to P+9 is performed in steps Pδ to P3Q.
is decremented one by one and this process is repeated until a=0 at the cycle set in step P32. Therefore, in the range of a, as shown in FIG. 7, the return speed is low near the middle position of the steering system. It gradually decreases and reaches zero at the middle position.

When a=0 in step P27, the process returns to step P2.

Therefore, in addition to the effects of the above-mentioned embodiments, this embodiment has the advantage that each detection signal does not have to be read every time it is processed, so the control speed becomes faster, and there is no need to perform position detection at the time of return.

In the above two embodiments, the switch means is a manual switch that is turned on by the driver's will, but the switch means is not limited to this, and the switch means may be linked to the ignition key. The electric motor may also be configured to automatically return the steering wheel to the middle position when the engine is started.Also, since the electric motor is also used as an electric motor for electric power steering to reduce the steering force of the steering system, the cost is reduced. It is advantageous in terms of height and space.

(Effects of the Invention) As explained above, according to the present invention, since the motor is configured to return to its original state using a detection signal corresponding to the motor rotation speed, the steering system can be set regardless of the magnitude of the road surface load. It can be returned to the intermediate position at the return speed. In addition, it is possible to gradually reduce the return speed near the middle position, preventing the occurrence of hunting near the middle position, allowing the return operation of the steering system to operate smoothly, and improving marketability. I can do it.

[Brief explanation of drawings]

1(a') to 5 show an embodiment of the intermediate position return device according to the present invention, FIG. 1(a) is a longitudinal sectional view showing the steering system, and FIG. 1(b) is a longitudinal sectional view showing the steering system. A plan view showing the potentiometer, FIG. 2 is a schematic configuration diagram showing the intermediate position return device,
FIG. 3 is a flowchart showing the outline of the control process, and FIG. 4 is a diagram showing the relationship between displacement and detection signals S2 and S.
Fig. 5 is a diagram showing the relationship between displacement and return speed, Figs. 6 and 7 show other embodiments of the present invention, Fig. 6 is a flow chart showing an outline of the control process, and Fig. 7 is a diagram showing the relationship between displacement and return speed. It is a figure showing the relationship between the displacement and return speed. In the drawing, (9)...Electric motor (10)...Electric motor control means (control device) (16).
...Position detecting means (19)...Switch means (38)...Rotation detecting means ΔC...Deviation.

Claims (1)

[Scope of Claims] 1) Position detection means for detecting the steering position of the steering system, rotation detection means for detecting the rotational speed of the electric motor, switch means, and an output from the position detection means when the switch means is turned on. Determine and output a motor control signal based on the signal, drive control the motor based on a deviation between the motor control signal and the output signal from the rotation detection means, and return the steering system to the neutral position. 1. An intermediate position return device for a steering device, comprising: electric motor control means. 2) Claim 1, wherein the switch means is constituted by a manual switch provided in the vehicle interior near the driver's seat.
A device for returning the steering device to an intermediate position as described in Section 3.