JPS6338082A - Motor-driven power steering device - Google Patents

Abstract

PURPOSE:To certainly prevent the erroneous operation of an electric driving mechanism due to the detection of anomaly by preventing the delay of response by exciting the electric motor of the electric driving mechanism when a steering power detecting means detects anomaly. CONSTITUTION:When a torque sensor 40 detects anomaly, and the torque detecting signal shows an anomaly value, the sensor anomaly detection signal (a) is set at a low level L. Because of the signal (a), an RL clock outputs the signal (c) at a low level L continuously afterwards, and suppresses a PWM signal (f) at an AND gate AN1. When the signal (c) is set at a low level L, a main relay MR is deenergized, and the power source line of an electric motor 8 is cut off. The signal (c) does not return to a high level H unless an ignition key IC is turned-ON again. Therefore, after the torque sensor 40 detects anomaly, excitation of the electric motor 8 is cut off. In this case, a steering wheel gets the weight in the manual steering.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a power steering device that reduces the force to be applied to a steering means such as a steering wheel for steering a vehicle. The electric drive mechanism detects the steering force applied from the steering means to the direction setting mechanism that determines the running direction of the vehicle, and applies an auxiliary steering force corresponding to the magnitude of the steering force. This invention relates to an electric power steering device added to a direction setting mechanism.

(Prior Art) When changing the direction of tires, a large force is required to rotate the steering wheel when the vehicle is stopped or traveling at low speed. Especially recently, F.
The number of F vehicles is increasing, and since the front wheels of this type of vehicle serve as the drive shaft, they require even greater steering power.

Therefore, a power steering device has been proposed that assists the driver's steering force. This system generates driving force in response to the driver's steering force and transmits this force to a direction setting mechanism (hereinafter referred to as a steering system) that determines the direction in which the vehicle travels. Most power steering devices currently in practical use are hydraulic. That is, it includes a control valve, a hydraulic cylinder, a pump, etc., and generates auxiliary steering force by moving oil in accordance with the steering force.

Generally, in this type of equipment, components such as control valves, hydraulic cylinders, and pumps are distributed and connected by pipes, but the pipes can only be bent at a curvature of more than a predetermined value due to large pressure loss. Can not. Further, in a hydraulic power steering device, it is necessary to securely seal the device to prevent oil leakage, and installation of the device is troublesome. Therefore, in a vehicle such as a front-wheel drive vehicle with a small amount of remaining space 411, there are many problems in installing the power steering device.

A solution to this problem is to use an electric motor as a drive source, detect the steering force applied to the steering system from the steering means, and apply an auxiliary steering force corresponding to the magnitude of this steering force from the electric motor to the steering system. Electric power steering devices have been proposed.

According to this, not only the device becomes smaller and the space utility improves, but also the combination with the electronic control device,
Conventional hydraulic power steering devices can generate various auxiliary steering forces (for example, auxiliary steering forces depending on vehicle speed) that require additional devices.

(Problems to be solved by the invention) By the way, in this type of electric power steering device,
Very high reliability is required for the accuracy of the steering force detection means that detects the steering force applied to the steering system from the steering means. In other words, when the steering force detection means outputs an abnormal signal, a corresponding abnormal auxiliary steering force is applied to the steering system. Specifically, for example, if the steering force detection means malfunctions and generates an abnormality detection signal even though the driver is not steering the vehicle due to an increase in temperature inside the vehicle while the vehicle is running,
A corresponding auxiliary steering force is applied to the steering system, changing the direction of travel of the vehicle regardless of the driver's will.
(hereinafter referred to as autosteer) may occur.

In preparation for such a situation, an electric power steering device has been proposed in which a relay means is inserted in the power supply line of the electric motor, and the power supply line is cut off by the relay means when the steering force detection means outputs an abnormal detection signal. . According to this, when an abnormality occurs, the power supply line of the electric motor is cut off, so manual steering is performed, and locking of autosteering and the steering system can be prevented.

However, in general, the response delay of the relay means used in this type of device is about 20 to 30 seconds, and abnormal signals that change relatively rapidly, such as when the steering force detection means experiences temperature drift. is output, the motor is energized with a small amount of power, so the responsiveness of this relay means is not a problem, but as in the case where the output signal line of the steering force detection means is disconnected or shorted, When an abnormal signal that suddenly changes to the maximum or minimum value is output, the motor is energized with a large amount of power, so the responsiveness of this relay means becomes a problem. In other words, before the relay means responds and cuts off the power supply line of the electric motor, the electric motor is energized with a large amount of power, and a large erroneous auxiliary steering force is applied to the steering system, resulting in a serious danger to vehicle operation. There is a risk.

SUMMARY OF THE INVENTION An object of the present invention is to reliably prevent malfunctions of an electric drive mechanism due to detection abnormalities of a steering force detection means of an electric power steering device.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention detects the steering force applied from the steering means by the steering force detection means, and provides assistance corresponding to the magnitude of the steering force. Steering force, ffi
In an electric power steering device that is applied from a dynamic drive mechanism to a steering system, an abnormality detecting means outputs an abnormal signal indicating a detected abnormality when a detected steering force of the steering force detecting means exceeds a predetermined range; and a detected steering of the steering force detecting means. The apparatus includes an energizing means for energizing the electric motor of the electric drive mechanism in accordance with the force and deenergizing the electric motor of the electric drive mechanism when the abnormality detection means outputs an abnormality signal.

(Operation) According to this, if there is an abnormality in detection by the steering force detection means, the electric motor of the electric drive mechanism is not energized, so that malfunction of the electric drive mechanism due to abnormality in detection can be reliably prevented.

In other words, in the conventional technology, when there was a detected abnormality, the energized motor was stopped, resulting in a delay in response from the occurrence of the abnormality until the motor stopped, but in the present invention, the detected abnormality is If there is, the motor will not be energized, so
There will be no response delay at all.

Such a biasing means may, for example, respond to the detected steering force by
Pulse generating means that outputs an energization control pulse that sets energization/de-energization of the motor, with a wide pulse width when the pulse width is large, and a wide pulse width when it is small; This is achieved by comprising a blocking means for blocking the output of the energization control pulse, a switching means inserted in the power supply line of the motor, and a switching driver that energizes the switching means while the energization control pulse is present.

In this case, when the abnormality detecting means outputs an abnormality signal, the energization control pulse is blocked, so that the electric motor is not energized.

Furthermore, in particular, the abnormality detection means, after once emitting the abnormality signal, continues to output the abnormality signal.
Safe driving of vehicles from Part 9 onwards is ensured.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(Example) FIG. 1 shows an outline of the structure of a mechanical section according to an embodiment of the present invention.

The first steering shaft 2 to which the steering wheel l is fixed has a first universal joint 4 and a second universal joint 4.
A steering shaft 5 is coupled. A rod 7 is connected to the second steering shaft 5 at a second universal joint 6. This rod 7 is coupled to an output shaft (21, described later) of the speed reducer 9, on which a pinion gear (22, described later) is formed. The pinion gear (22) meshes with a rack 11 fixed to the tie rod 10. Tie rod 10 is coupled to a steering knuckle arm 16 of axle 12. A shock absorber 13 is coupled to the axle of the wheel 12, and a suspension upper support 14 of the shock absorber 13 is coupled to a vehicle body (not shown). 15 is a coil spring for vibration damping between the upper support 14 and the axle; 18 is a lower suspension arm; 19
is a stabilizer bar.

The internal structure of the speed reducer 9 is shown in FIGS. 2a and 3. The upper end of the rod 7 is connected to the second steering shaft 5 via a second universal joint 6 (see FIG. 1). Slightly below the upper end of the rod 7, a sleeve 30 is fixed to the reducer case 31 via a pin 29 (see FIG. 2a). Rod 7 is sleeve 30
The output shaft 21 is fixed to the lower end of the output shaft 21 by a pin 20. The output shaft 21 is axially supported by a reduction gear case 24, and a pinion gear 22 formed at its lower end meshes with the rack 11. Therefore, steering wheel 1 (
(Fig. 1) rotates.

First steering shaft2. 1st universal joint 4. The output shaft 21 is rotationally driven through the second steering shaft 5, the second universal joint 6, and the rod 7, and the rack 11 that meshes with the pinion gear 22 formed on the output shaft 21 is thereby driven as shown in FIG. 2a. The wheel 12 (FIG. 1) changes its direction by being driven in a direction perpendicular to the plane of the paper (the direction in which the tie rod 10 extends in FIG. 1).

Further, a ring gear 23 is formed at the hollow upper end of the output shaft 21, and an intermediate gear 25 is supported by the case 24.
It meshes with the Another intermediate gear 26, which is coaxial with and integral with the intermediate gear 25, meshes with the input gear 27. The input gear 27 is fixed to the output rotating shaft 28 of the electric motor 8, and when the electric motor 8 is energized, the gear train 27-26
．． 25-23, the output shaft 21 rotates, and the rack 11 that meshes with the pinion gear 22 formed on the output shaft 21 rotates through the second rack 11.
The direction of the axle 12 (FIG. 1) changes by being driven in a direction perpendicular to the paper plane of FIG. 1 (the direction in which the tie rod 10 extends in FIG. 1).

In this way, the rotation of the steering wheel 1 and
The direction of the wheel 12 changes depending on whether the electric motor 8 is energized in the forward or reverse direction.

A wheel 32 is rotatably formed on the sleeve 30. That is, the sleeve 30 passes through the wheel 32. As shown in FIG. 4, the outer surface of the sleeve 30 has a round bottom groove 3 obliquely intersecting the central axis of the sleeve 30.
3 is formed, and a ball 34 is fitted into this round bottom groove 33.

This ball 34 is supported by the wheel 32. A narrow groove 35 is formed in the wheel 32, and the upper end of a pin 36 fixed to the upper end of the output shaft 21 enters into this groove 35. This pin 36 restricts rotation of the wheel 32.

When the rod 7 rotates, the sleeve 30 and the output shaft 21 rotate.
are fixed to the lower ends of the rods 7, so if the load on the output shaft 21 is large, the rods 7 will be twisted. The rotation angle between the sleeve 30 and the output shaft 21 deviates by an amount equivalent to this amount of torsion, and the wheel 32 rotates in the same manner as the output shaft 21 via the pin 36. This results in a rotation angle deviation of 32 degrees.

By the way, the sectional view taken along the line I[B-JIB in Figure 2a is shown in Figure 2b.
As shown in the figure. Referring to FIG. 2b, the sleeve 30 and the output shaft 21 are formed into a planar shape at this portion, and are opposed to each other to form a dihedral portion. This width across flat portion limits the rotational angle deviation between the sleeve 30 and the output shaft 21 that exceeds a predetermined value.

That is, within the range limited by the width across flats, the sleeve 30 rotates extra with respect to the wheel 32 by an amount equivalent to the deviation of the rotation angle, and the groove 33 of the sleeve 30 is aligned with the central axis of the sleeve 30. Since the grooves 33 are diagonal, the ball 34 is pushed upward or downward, and the wheel 32 supporting the ball 34 moves upward or downward.

Therefore, if the steering torque (steering force) applied to the steering wheel 1 is less than or equal to the predetermined value, the torque corresponds to the twist of the rod 7, and the wheel 32 moves to the upper or lower position corresponding to the amount of twist. do.

In other words, the vertical deviation of the wheel 32 (more precisely, the amount of movement upward or downward from the zero steering torque position) corresponds to a steering torque that is less than or equal to the predetermined value.

The wheel 32 has a ring-shaped groove 37 in which a ball 39 is engaged. This situation is shown in FIG.

The ball 39 is supported at one end of the elastic plate 38.

The other end of the elastic plate 38 is fixed. The elastic plate 38 includes
Torque sensors 40 each consisting of two strain detection elements (electrical elements whose resistance value changes depending on strain), one each on the front surface and the back surface, are bonded.

These two strain detection elements are connected in series, and the potential at the connection point (one receives compressive stress and the other receives tensile stress, and their respective resistance values change) is taken out as a torque detection signal. Therefore, the rod 7 is twisted in response to the steering torque applied to the steering wheel 1, and the wheel 32 is twisted.
When the wheel moves upward from the zero position, the elastic plate 38 is bent upward or improperly due to the engagement between the groove 37 and the ball 39, and the torque sensor 40 detects the amount of deviation of the wheel 32 (from the zero steering torque position). (deviation), that is, the amount of twist of the rod 7, that is, the applied steering torque. As mentioned above, since the amount of twist of the rod 7 is limited by the width across flats formed in the output shaft 21 and the sleeve 30, the torque sensor 40 can be rotated within the predetermined range as shown in FIG. When the steering torque is applied within the specified range, the output is linear, and when the steering torque is applied beyond the predetermined range, the output is saturated.

FIG. 5 shows a block diagram of an electric control device that rotates the electric motor 8 based on the output signal of the torque sensor 40, and FIG. 6 shows a detailed circuit diagram of each block. The graphs shown in each block in FIG. 5 show the electrical input/output characteristics of the block, with the horizontal axis representing the input level and the vertical axis representing the output level.

First, each block will be explained with reference to FIGS. 5 and 6.

<Bl block> Integrated circuit ICI (μP C14305H in this example)
This is a constant voltage circuit that uses a
A constant battery voltage (power supply voltage) is applied to supply a constant voltage Vcc to each block.

<82 block> This is a differential amplifier circuit mainly composed of operational amplifier op2, and when the battery voltage (power supply voltage) is smaller than the value obtained by dividing voltage Vcc by resistors R1 and R2,
A positive voltage Ve corresponding to the difference between them is output. Note that a smoothing circuit is provided on the input side of op2 to prevent error movements due to instantaneous fluctuations in the power supply voltage.

<86 Block> First reference voltage vl setting circuit, where vl is set equal to the neutral potential of the torque sensor 40 (potential when no torque is applied) by the variable gripper VRI. The first reference voltage ■1 is the B4 block.

Given to B5 and B7 blocks.

<84 block> PI centered around operational amplifiers op4a and op4b
This is a D compensation circuit (proportional-integral-differential compensation circuit), which smoothes fluctuations in the output signal (torque detection signal) of the torque sensor 40 due to mechanical delays in the steering system.

This block has a first reference voltage Vt from the B6 block.
is given, and for the DC input, the difference from the voltage v1 is linearly amplified.

Note that in the following description, this B4 block output will be referred to as a torque detection signal.

As mentioned above, since the amount of twist of the rod 7 is limited by the width across flats formed on the output shaft 21 and the sleeve 30, the maximum value of the torque detection signal is 2.2V, and the minimum value is 0. .8■. FIG. 11 shows the relationship between the torque detection signal and the applied steering torque.

<33 block> This is a window comparator consisting mainly of two operational amplifiers op3a and op3b and an AND gate AN6. (output signal of the integrating circuit) is detected. When the torque detection signal goes above the set upper limit level, the comparator centered around the operational amplifier op3a outputs a low level L (open collector output), and when the torque detection signal goes below the set lower limit level, the comparator centered around the operational amplifier op3b outputs a low level L (open collector output). The logical product of these outputs is output from the AND gate AN6. AND gate AN6 output indicates normal detection of torque sensor 40 at high level H, and normal detection of torque sensor 40 at low level L.
The sensor abnormality detection signal a indicates abnormality detection. As shown in FIG. 11, the torque detection signal of the present device has a maximum value of 2.2V centered around 1.5V and a minimum value of 0.8V during normal detection. Therefore, the upper limit level is 2.5V,
The lower limit level is set to 0.5V, and if it deviates from this level, it is considered that an abnormality has been detected. However, each of the above comparators is provided with hysteresis characteristics to prevent chattering.

<85 block> This is a comparator that compares the torque detection signal and the first reference voltage ■1, which are mainly composed of the operational amplifier op5,
A rotation signal d indicating whether the steering wheel l is rotated left or right is output. This circuit has hysteresis characteristics to prevent chattering.

In other words, if the torque detection signal 4B is equal to or higher than the value near the first reference voltage v1, a low level L (open collector output) indicating rightward rotation of the steering wheel 1 is output as the rotation signal d, and the torque detection signal If is less than a value near the first reference voltage v1, a high level H (open collector output) indicating leftward rotation of the steering wheel l is output.

<87 Block> Consists of a first differential amplifier circuit mainly composed of an operational amplifier op7a, a second differential amplifier circuit mainly composed of an operational amplifier op7b, and a linear amplifier circuit mainly composed of an operational amplifier op7c. . The first differential amplifier circuit amplifies the difference between the torque detection signals of the first reference voltage ■1 or less (that is, the leftward rotation of the steering wheel l), and the second differential amplifier circuit amplifies the first reference voltage ■! The difference between the above torque detection signals (that is, the rightward rotation of the steering wheel l) is amplified, the respective outputs are added together, and linear amplification is performed in a linear amplification circuit. The output signal of the B7 block, that is, the absolute value of the torque detection signal (strictly speaking, the first reference voltage
The absolute value of the difference (hereinafter referred to as absolute torque signal) is given to the BIO block and the Bll block.

<38th Block> This is a sawtooth wave generation circuit centered on the integrated circuit IC2 (μPCl555 is used in this embodiment).

<89 block> This is an addition circuit that adds the second reference voltage (2) to the sawtooth wave output of the B8 block (shifts the sawtooth wave by V2). This second reference voltage v2 is set by a steering force variable volume and a variable resistor VR2 provided at the driver's seat.

<B10 block> This is a comparator centered around the operational amplifier oplO, and the dead zone (Q3
．． (area where Q4 is off) is set. here,
Set voltage and absolute torque (No. 4 (
B7 output), and if the absolute torque signal is above the set voltage, the response signal θ is set to high level H (open collector output), and if the absolute torque signal is below the set voltage, the response signal e is set to low level L. (open collector output) and output. The response signal e has a high level H to indicate that there is a response, and a low level to indicate that there is no response. Note that this circuit has hysteresis characteristics to prevent chattering.

<ntt block> “This is a comparator composed mainly of the performance amplifier OPH, and it is a comparator that outputs the absolute torque signal after clamping (r3, which will be described later).
A) which is clamped by a clamp signal of 16 outputs,
The shifted sawtooth wave (I38 output) is compared with B. This output mode is shown in FIG. 10, and when signal A is larger than signal B, high level H (open collector output) is output.
When signal B is larger than signal A, a low level L (open collector output) is output from the PWM signal port.

By the way, the variable resistor V of the BIO block mentioned above
The voltage set by R3 is set lower than the voltage of the signal A, which is at the PWM signal port level H.

In other words, the PWM signal signal A does not reach the high level H unless it becomes larger than the dead zone. As a result, the electric motor 8
The drive becomes smooth.

<812. B13 block> Each of the current detection circuits has the same configuration; the voltage across the shunt resistor R3 is differentially amplified by a differential amplifier including an operational amplifier 0P12, and the voltage across the shunt resistor R4 is amplified by a differential amplifier including an operational amplifier 0P13. Differential amplification is performed using a differential amplifier. A protection circuit is provided at the input of each amplifier circuit.

B14 Block This is a non-inverting amplifier mainly composed of an operational amplifier op14, which adds the B12 output and the B13 output. The B14 output is the current detection signal.

<815 block> This is a non-inverting amplifier mainly composed of operational amplifier op15, in which the current detection signal of B14 output is connected to B2.
Add the output voltage ■c. That is, when the power supply voltage decreases, Va increases, so the current detection signal is shifted to the higher side.

<B16 block> This is an integration circuit centered around the operational amplifier op16, which averages the shifted current detection signal and outputs it as a clamp signal. In this case, when the current detection signal (after shifting) is higher than the voltage set in the variable resistor VR4, the clamp signal is lowered according to the difference. In other words,
The clamp signal is set to a lower value as the power supply voltage (voltage of the battery Bt) is lower and as the energizing current of the motor 8 is larger. This clamp signal is connected to the diode D
Absolute torque signal (B7 output) applied to the cathode of
to clamp.

FIG. 9 shows the correlation between the signal A after clamping, the absolute torque signal, and the clamp signal. Referring to FIG. 9, when the clamp signal is high enough, signal A becomes an absolute torque signal, and when the clamp signal becomes low, the maximum value of signal A becomes low. Therefore, as shown in Fig. 10, even if the absolute torque signal increases as shown by the broken line, it is clamped by the clamp signal as shown by the solid line, so the PWM signal pulse width will not be wider than the width corresponding to the clamp signal. It won't happen. This means that the amount of energization of the electric motor 8 is limited.

Block B17 This is an abnormality detection circuit for the energizing current of the motor 8 centered on the operational amplifier op17, and is a comparator that compares the current detection signal (after shifting) with a set value.

In this case, if the current detection signal (after shift) is below the set value, the current abnormality detection signal is set to a high level H (open collector output) indicating no abnormality, and When exceeds the set value, the current abnormality detection signal S is set to a low level L indicating that there is an abnormality.The current tool tit detection signal S is given to the RL block. Once level L is reached, P
The WM signal is muted and the main relay MR is deenergized.

Block B18 This is an abnormality detection circuit for the energizing current of the motor 8 centered around the operational amplifier 0P18, and is a comparator that compares the current detection signal (after shifting) with a set value.

In this case, if the current detection signal (after shift) is lower than the voltage set by variable resistor VR5, the PWM blocking signal g is set to high level H (open collector output) indicating no blocking, and the current detection signal (after shift) is set to high level H (open collector output) indicating no blocking. ) exceeds the set voltage, the PWM blocking signal g is set to a low level L indicating blocking.The PWM blocking signal g is given to the main logic ML.

As will be described later, the PWM blocking signal g of this B18 output
is a PWM signal (strictly speaking, ML anime game) -AN2.
AN3 output) is negatively clamped to prevent the motor 8 from being energized. In the case of excessive energizing current, the current detection signal becomes smaller by blocking the energizing, so p W M III
I stop signal g changes to high level 1) without blocking, 818
acts as if chopping the PWM signal, and ff
Reduce the average energizing current of 1vJJW8.

Also, since there is a relationship between the set voltage of 816, the set voltage of B18, and the set voltage of B17, the electric voltage i (battery B
t, t, ffi pressure) is low and the energizing current of the motor 8 is large, the pulse width of the PWM signal f is first limited, and then the PWM signal (strictly speaking, the AND gate AN of ML is
2. If the condition (low voltage and/or large energizing current) is still not improved, the PWM signal f is blocked and the power supply to the motor 8 is cut off by the main relay MR.

Block R [4 block] This is a logic circuit consisting of an AND gate AN7 and a latch circuit IC3, and the correlation between the input sensor abnormality detection signal a and current abnormality detection signal and the output signal C is shown in Table 1 below. In addition, in Table 1, high level is +HI+
, the low level is indicated as "L".

Table 1 When the ignition switch IG is initially turned on, the latch circuit IC3 is reset, so the output signal C becomes a high level H, and then the sensor abnormality detection signal a and ? l
Both current abnormality detection signals are at high level without any abnormality!
-(), the high level is H. However, when either of the signals on the negative side goes to a low level L indicating that there is an abnormality, the output signal C becomes a low level L, is latched by the latch circuit IC3, and is held as it is unless the ignition switch IG is turned on again.

Output signal C is given to relay driver RD and main logic ML.

<RD block> This is a relay driver consisting of transistors TRl0 and TRII, and the base input of TR10 (RL output signal C
) is at a high level H, a main relay MR inserted in the IT source line of the motor 8 (a line connecting the emitters of power transistors Ql and Q2 and batteries Bt, t, which will be described later) is energized.

A switch TH3W inserted in the power supply line of the main relay MR is a power transistor Ql.

Q2. This is a thermal switch installed on the heat sinks of Q3 and Q4 to prevent overheating. When at least one of Q1 to Q4 overheats and the temperature of the heat sink exceeds a predetermined value, the switch opens and the MR power supply line is disconnected. Cut off.

<ML block> AND gate AND, AN2. AN3. AN4 and A
This is a logic circuit whose main component is N5.

Signal C of the RL block output and PWM signal f of the B11 block are applied to the AND gate ANI. That is, the ANI blocks the PWM signal when the sensor abnormality detection signal a or the current abnormality detection signal is abnormal. A
The NI output is given to one input terminal of AN2 and AN3.

The other input terminal of AND gate AN2 is a transistor T.
A signal obtained by inverting the rotation signal d is given by RI. Therefore, AN2 outputs the PWM signal of the ANI output when the rotation signal d is at a low level L (that is, rotation to the right). A
The N2 output is given to the pace driver I3D, but since a PWM blocking signal is applied to the cathode of the diode D2, when the signal g is at a low level L, it is negatively clamped and the output is blocked.

A rotation signal d is applied to the other input terminal of the AND gate AN3. Therefore, AN3 outputs a PWM signal (ANI output signal) when the rotation signal d is at a high level H (that is, main rotation). The AN3 output is given to the pace driver BD, but since the PWM blocking signal part is applied to the cathode of the diode D3, when the signal g is at a low level L, it is negatively clamped and the output is blocked.

The transistor TR is connected to the 1st input terminal of the AND gate AN4.
A signal obtained by inverting the rotation signal d is given by I, and a response signal e of the BIO block output is given to the other input terminal. Therefore, in AN4, the rotation signal d is at a low level L (
In other words, when the response signal e is at a high level H in a counterclockwise rotation), a high level H is output.

The rotation signal d is applied to one input terminal of the AND gate AN5, and the response signal e of the BIO block output is applied to the other input terminal. Therefore, A N 5 outputs a high level H when the rotation signal d is at a high level H (that is, main rotation) and the response signal e is at a high level H.

<BD block> Pace driver BD has transistors TR2 and TR
3, a base driving circuit of power transistor Q2 consisting of transistors TR4 and TR5, a base driving circuit of power transistor Q3 consisting of transistors TR6 and TR7, and a transistor T.
It has a base driving circuit of power transistor Q4 consisting of R8 and TR9. Since it does not change the input/output apart from the level, it can be considered a pass-through.

<TMI, TM2 block> Power transistor Ql that energizes electric motor 'v18 in forward and reverse directions.
, Q2. Consists of Q3 and Q4. The collectors of Ql and Q2 (considering each as one transistor as shown in Fig. 5) are connected to the positive terminals of the on-board battery Bt, t via the relay contacts of the main relay MR, and the emitters of Q3 and Q4 are As shown in Figure 5, the on-board battery Be! , is connected to the negative pole of .

During normal operation (sensor abnormality detection signal a and current abnormality detection signal but no abnormality, PW
The power transistor Q2 is turned on/off by the PWM signal when the rotation signal d is at a low level L (that is, left rotation) when the M blocking signal is no blocking (same as 2 or less); the power transistor Q2 is in normal operation.

When the rotation signal d is at a high level H (that is, main rotation), P”vV
The power transistor Q3 is on/off controlled by the M signal; the power transistor Q3 is on/off controlled by the AN4 output (rotation signal d
is turned on when the rotation signal d is at a low level and the response signal e is at a high level H); the power transistor Q4 is on/off controlled by the output of AN5 (turned on when the rotation signal d is at a high level H and the response signal e is at a high level H); ) to be done.

The motor 8 is energized to rotate normally when the power transistors Q1 and Q3 are on, and the motor 8 is energized to rotate normally when the power transistors Q1 and Q3 are on.
When 4 is on, reverse bias is applied.

Here, the input signals c and d of the main logic ML.

Power transistor Ql for e, f and g.

Q2. The base applied signals for Q3 and Q4 are summarized in Table 2 below. However, in Table 2, '*'' means don'
t care (don't care: high level H or low level L is fine), -'' is don'j determine
e (don't determine: do not consider the output), ゛and''
is PWM control, input a Cr d, er f and g are "H" or "L'" is high level 14 or low level L human power (IC level), power transistor Ql
, Q2. It is assumed that "H" or "L" of the base application signals of Q3 and Q4 indicate high level H (on level) or low level L (cutoff level) input, respectively.

A series of operations of the electric power steering device of this embodiment using the electric control device described above (FIGS. 5 and 6) will be explained.

(1) When the ignition switch IG is turned on, a predetermined constant voltage is supplied to each block, and the block enters a standby state.

(2) When the driver of the vehicle turns the steering wheel 1 to the right, the steering system is mechanically driven as described above, and the attitude of the wheels 12 is changed to a direction that turns the vehicle to the right, and the steering The force is detected at the torque sensor 40, which outputs a signal higher than the neutral potential as a torque detection signal. Furthermore, when the driver of the vehicle turns the steering wheel 1 to the left, the steering system is mechanically driven as described above to change the attitude of the wheels 12.
The direction of the vehicle is changed to turn left, and the steering force is detected by the torque sensor 40.
0 outputs a signal lower than the neutral potential as a torque detection signal.

(3) As shown in Figure 1O, compare the magnitude of the torque detection signal, that is, the absolute torque signal (after clamping) A and the sawtooth wave (after shifting) B, and when the signal A is large, the signal becomes high. Since level H is output, the pulse width of the PWM signal train is proportional to the applied steering force. During this PWM signal train, the electric motor 8 is energized.

In addition, since the torque detection (the magnitude of the number i with respect to the neutral potential becomes a rotation signal d representing the rotation direction of the steering wheel 1 (low level L is rightward, high level H is leftward),
When the driver of the vehicle turns the steering wheel 1 to the right, the electric motor 8 is energized to rotate in the normal direction by the energizing power (average value) corresponding to the applied steering force, and the driver of the vehicle turns the steering wheel 1. When the motor 8 rotates to the left, the electric motor 8 is reversely biased by the biasing power (average value) corresponding to the applied steering force.

Since the auxiliary steering force is applied to the steering system by biasing the electric motor 8 in forward and reverse directions, the driver's steering force decreases and converges to a predetermined steering force. This convergence value can be adjusted using the steering force variable volume.

(4) When an abnormality is detected in the torque sensor 40 and the torque detection signal becomes an abnormal value (outside 0.5 to 2.5V), the sensor abnormality detection signal a is set to a low level L. In response to this signal a, the RL block outputs a signal C that continues to be at a low level L from then on, and PWM
Stop signal train. Furthermore, when the signal C becomes a low level L, the main relay MR is deenergized and the power line of the motor 8 is cut off. Signal C does not return to high level H unless the ignition key IG is turned on again.

Therefore, after an abnormality is detected in the torque sensor 40, the electric motor 8 is no longer energized. In this case, the steering wheel 1 becomes heavy for manual steering.

(5) When the power supply voltage (Bt, h voltage) decreases, the electric motor 8 is energized IE! The current sense signal that detects the current (average value) is shifted to a higher value, thereby setting a lower value clamp signal. Since the clamp signal clamps the absolute torque signal, when the clamp signal decreases as shown in FIG. 9, the maximum value of signal A is limited. When the maximum value of the signal A is limited, the maximum value of the pulse width of the PWM signal train is limited as shown in FIG. That is, as shown in FIG. 8, when the power supply voltage decreases, the motor energizing power is saturated at a smaller value of input torque (steering force).

The relationship between the power supply voltage and the maximum energizing power of the motor 8 is shown in the graph of FIG.

When the current detection signal after the shift exceeds a higher value by 1, PW
Mμ■ Generates a stop signal g to negatively clamp the PWM borrow signal f (conditionally in normal operating state: AN2, AN3 output). Due to this? %! Since the flow detection signal has a low value, P
The WM blocking signal g disappears, and this process is repeated. In other words, the energizing power (average value) of the electric motor 8 is lowered by chopping the PWM signal sequence at the same cycle.

When the current detection signal after the shift reaches a higher value, the current abnormality detection signal is set to a low level L. In response to this signal, the RL block continues to output the low-level low-level signal C, and the PWM signal signal is stopped at the AND gate ANI. Furthermore, when the signal C becomes a low level L, the main relay MR is deenergized and the power line of the motor 8 is cut off. Signal C will not return to high level 1 unless ignition key IG is turned on again. (6) If power transistors Q1 to Q4 overheat, main relay MR is deenergized to cut off the power supply line of motor 8. .

〔Effect of the invention〕

As described above, according to the present invention, when there is a detection abnormality in the steering force detection means, the electric motor of the electric drive mechanism is not energized, so there is no response delay at all, and malfunctions of the electric drive mechanism due to detection abnormality are reliably prevented. can do.

Furthermore, as explained in the embodiments, the biasing means may include, for example,
A pulse generating means outputs an energization control pulse for setting energization/de-energization of the electric motor with a wide pulse width when the detected steering force is large and a wide pulse width when the detected steering force is small, and an abnormality detection means generates an abnormality signal. A blocking means for blocking the output of the energization control pulse from the pulse generating means when the energization control pulse is output, a switching means inserted in the power supply line of the motor, and a switching driver for energizing the switching means while the energization control pulse is present.

This is brought about by having the following.

In particular, the abnormality detection means may continue to output the abnormality signal after emitting the -carrier abnormality signal.
Safe driving of the vehicle thereafter is ensured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a general configuration of a mechanical structure according to an embodiment of the present invention. FIG. 2a is an enlarged sectional view of the reducer 9 shown in FIG.
4 is a sectional view taken along the line nA-11A in FIG. 3. FIG. FIG. 2b is a JIB-118u sectional view of FIG. 2a. FIG. 3 is a tn-n X-line cross-sectional view of FIG. 2. FIG. 4 is a plan view showing the outer surface of the sleeve 30 shown in FIGS. 2 and 3. FIG. FIG. 5 is a block diagram showing the configuration of the electrical control system of the apparatus shown in FIG. 1. FIG. 6 is a circuit diagram showing details of each block shown in FIG. 5. FIG. 7 is a graph showing the correlation between the electric power 1jX voltage of the device shown in FIG. 1 and the maximum energizing power of the motor. FIG. 8 is a graph showing the correlation between the applied steering force, the energizing power of the motor, and the power supply voltage of the apparatus shown in FIG. FIG. 9 is a graph showing the correlation between the absolute torque signal, signal A of FIG. 6, and the clamp signal. FIG. 10 is a waveform diagram showing an example of the input/output operation of the Bll block shown in FIG. 6. FIG. 11 is a graph showing the correlation between steering force and torque detection signal. l Steering wheel 2.5 Steering shaft 4.6: Universal joint 1.2.4, 5.6: (Steering means) 7: Rod
8: Electric motor (electric motor) 9: Reducer 8,9:
(Electric drive mechanism) 10: Tie rod 11: Rank 12: +jj import 13: Shosoku absorber 1
4: Suspension upper support 15: Coil spring 16: Steering knuckle arm 18: Lower suspension arm] 9 Stabilizer bar 20: Pin 21: Output shaft 22: Pinion gear 7.10, 11, 16.22: (Travel Direction setting mechanism) 23: Ring gear 24, 31: Reducer case 25. 26: Intermediate gear 27: Input gear 28: Rotating shaft 29: Pin 30 sleeve 32: Wheel 33. 35. 37: Groove 34. 39: Ball 3
6: Connecting pin 3a Two elastic plates 40: Torque sensor 40. B4: (Steering force detection means) ML: Main logic (blocking means) 87, B8. B9,1311: (Pulse generating means) Ql, 02. Q3. Q4: Power transistor (switching means) 8D two-pace driver (switching driver) [37
, [1B, [19,811, ML, 1130. Of~Q
4: (energizing means) anus: main relay (relay means) 1 (D: relay driver (relay driver) RL: relay logic (holding means) B3: (first comparison means, second comparison means 2 synthesis means) B3
．． RL: (Abnormality detection means) TIISW: Thermal switch Bjj: On-board battery patent applicant Aisin Seiki Co., Ltd.

Claims (6)

[Claims] (1) A running direction setting mechanism that determines the orientation of the wheels with respect to the vehicle body; Steering means that is coupled to the running direction setting mechanism and drives the running direction setting mechanism; Steering that detects the steering force applied from the steering means to the running direction setting mechanism Force detection means; Abnormality detection means that outputs an abnormality signal indicating a detected abnormality when the detected steering force of the steering force detection means exceeds a predetermined range; An electric drive mechanism including an electric motor coupled to the traveling direction setting mechanism; According to the steering force detected by the steering force detection means, when the steering force is large, the electric motor of the electric drive mechanism is energized with high electric power, and when it is small, with low electric power, and when the abnormality detection means outputs an abnormality signal, the electric motor of the electric drive mechanism is energized. An electric power steering device comprising: energizing means for deenergizing the electric motor. (2) The energizing means is a pulse generating means that outputs an energization control pulse that sets energization/de-energization of the electric motor, with a wide pulse width when the detected steering force is large and a narrow pulse width when the detected steering force is small. a blocking means for blocking the pulse generation means from outputting the energization control pulse when the abnormality detection means outputs an abnormality signal; a switching means inserted in the power supply line of the motor; The electric power steering device according to claim 1, further comprising: a switching driver that energizes the means. (3) The energizing means further includes a relay means inserted in the power supply line of the electric motor; and a relay driver that energizes the relay means while the energization control pulse is present. The electric power steering device according to item (2). (4) The abnormality detection means outputs a signal corresponding to the on level of the energization control pulse when the detected steering force is within a predetermined range, and outputs a signal corresponding to the off level of the energization control pulse when the detected steering force exceeds the predetermined range. binarization means for outputting an abnormal signal; the blocking means is a logic gate for outputting an AND of the abnormal signal and an output energization blocking pulse of the pulse generating means;
An electric power steering device according to claim (2). (5) When the detected steering force exceeds a predetermined range, the abnormality detection means continuously outputs an abnormality signal from then on and deenergizes the electric motor, the electric power according to claim (1). Steering device. (6) The abnormality detection means compares the detected steering force with a predetermined upper limit value, and when the former exceeds the latter, the first abnormality detection means outputs an upper limit abnormality signal.
Comparison means; second comparison means that compares the detected steering force with a predetermined lower limit value and outputs a lower limit abnormality signal when the former falls below the latter;
The electric power steering apparatus according to claim 5, further comprising: a synthesizing means for synthesizing an upper limit abnormality signal and a lower limit abnormality signal and outputting the abnormality signal; and a holding means for holding the abnormality signal.