JPH0359874B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a control device for a power steering device that takes safety measures into consideration in the event of a failure. [Prior Art] In general, a power steering device controls the flow rate of oil supplied from an oil pump to a power steering section using, for example, a solenoid valve according to driving conditions, and provides light steering force over a wide range of driving speeds. I'm trying to get that. However, in such a conventional device, if a sensor that detects running conditions fails, the oil flow rate is set to the maximum value or the minimum value, making it difficult to operate. For this reason, it is conceivable that the solenoid valve holds the plunger in a position where the oil flow rate becomes an intermediate flow rate when it is not energized, and increases or decreases the oil flow rate by controlling the moving direction of the plunger. Such a solenoid valve not only has a complicated structure, but also requires delicate adjustment, resulting in poor economic efficiency and stability. [Object and Structure of the Invention] Therefore, an object of the present invention is to provide a control device for a power steering device that takes measures against failure of a sensor that detects running conditions, and also ensures economic efficiency and stability. It is in. In order to achieve this object, the present invention controls the oil flow rate to an intermediate flow rate when the signal from the load sensor changes when the vehicle speed sensor fails. Hereinafter, the present invention will be explained in detail using drawings showing embodiments. [Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, numeral 1 denotes a vehicle speed signal generating circuit, which generates a vehicle speed signal whose pulse number changes depending on the vehicle speed. Reference numeral 2 denotes a steering signal generating circuit, which generates a steering signal with a number of pulses corresponding to the amount of steering. 3 is a heavy load detection circuit, which generates a heavy load signal of "0" level when the load value is larger than a predetermined value, and 4 is a light load detection circuit, which generates a heavy load signal of the "0" level when the load value is larger than a predetermined value. When the load value is small, a light load signal of "0" level is generated. 5 is a D/A conversion circuit, 6 is a solenoid coil drive circuit, and 7 is a solenoid coil, and the solenoid coil drive circuit 6 controls the duty ratio of the signal output according to the voltage supplied from the D/A conversion circuit 5. At the same time, the duty ratio of the output signal is also controlled according to the value of the current flowing through the solenoid coil 7. Further, the solenoid coil 7 controls a valve (not shown) provided in the oil passage according to the duty ratio of the signal supplied from the solenoid coil drive circuit 6, and controls the amount of oil supplied to the power steering device. It's getting old. 8 is a control circuit, 9 is an attached circuit,
The control circuit 8 generates an oil flow rate setting signal for controlling the oil flow rate supplied to the power steering device according to the vehicle speed signal and the steering signal and supplies it to the D/A converter 5, and also controls the oil flow rate according to the load value. It is designed to correct the setting signal. In addition, this control circuit 8 controls the oil flow rate when any one of the vehicle speed signal generation circuit 1, steering signal generation circuit 2, heavy load detection circuit 3, and light load detection circuit 4, which are driving condition sensors, ceases to generate a signal. It is designed to be set to the optimal value at that time. The attached circuit 9 is designed to generate an initial reset signal IR, a clock signal CL, and a manual control signal MC for adjusting the steering force according to the driver's preference. In order to realize the above-mentioned functions, the control circuit 8 includes an instantaneous vehicle speed calculation circuit 80 that calculates an instantaneous vehicle speed signal from the pulse signal period generated from the vehicle speed signal generation circuit 1;
An average vehicle speed calculation circuit 81 that calculates an average vehicle speed signal for 30 seconds based on a vehicle speed signal, an average steering amount calculation circuit 82 that calculates an average steering signal for 30 seconds based on a steering signal, a heavy load detection circuit 3, and a light Load detection circuit 4
The load detection circuit 83 generates a load signal based on the signal generated from the vehicle, and the relative relationship between the average vehicle speed signal and the average steering amount signal indicates whether the road is in an urban area, a suburban area, or a high speed. A driving condition decoder 84 generates a condition signal (however, when the value of the average steering amount is zero, it generates a signal representing intermediate mode, that is, suburban driving regardless of the value of the average vehicle speed), An oil flow decoder 85 that decodes the oil flow signal supplied to the steering device, a control pattern decoder 86 that generates a control pattern signal for correcting the oil flow signal from the driving condition signal and the load signal, the oil flow signal and the control pattern signal. An oil flow rate setting circuit 87 that generates an oil flow rate setting signal for controlling the oil flow rate by adding 1 msec, 10 msec, 3 seconds, 10 seconds, which is the operation reference signal for each circuit.
Reference signal generation circuit 8 that generates a signal with a period of 30 seconds
8. Intermediate flow rate setting conditions, that is, a state where the vehicle speed signal is not generated and the load condition is changing, and a state where the count value of the 3-second clock counter, which will be described later, is 5 (this state will be described later, but Control is performed so that the signal sent from the oil flow rate setting circuit 87 becomes an intermediate flow rate when the vehicle speed is not occurring and three or more steering pulses are not generated within three seconds. It is comprised of an intermediate flow rate signal generation circuit 89 that generates a signal, and a comparison circuit 90 that detects that three or more steering pulses have been generated. The instantaneous vehicle speed calculation circuit 80 is composed of an OR circuit 80a, a clock counter 80b, and a register 80c.The clock counter 80b counts up each time a signal is supplied to terminal C, and when a signal of level "1" is supplied to terminal R. The counting result is reset each time it is supplied. Then, the register 80c is supplied with a signal having a period of less than 1 second to the terminal C, and when that signal falls twice or more, the register 80c inputs the signal that is being supplied to the terminal D at that time every time the signal falls. It captures and stores the stored signal and outputs the stored signal, and when a "1" level signal is supplied to terminal R, the stored contents are reset. The average vehicle speed calculation circuit 81 includes a vehicle speed counter 81a,
Delay circuit 81 that delays the input signal by 1 microsecond
b, a register 81c, and the average steering amount calculation circuit 82 includes a steering counter 82a and a delay circuit 82.
b, and a register 82c. Then, a vehicle speed counter 81a and a steering counter 82
A has the same function as the clock counter 80b, and a delay circuit 82b has the same function as the delay circuit 81b. The load detection circuit 83 includes AND circuits 83a, 83
b. A falling detection circuit 83d that generates a pulse signal every time a falling edge of the vehicle speed signal occurs; a rising/falling detection circuit that generates a pulse signal when either the heavy load signal or the light load signal rises or falls; 1, which includes a circuit 83e, a counter 83f ₁ , a comparator 83f ₂ , and a constant generation circuit 83f ₃ , and the count value of the counter 83f ₁ that counts the signal supplied to the terminal C is output from the constant generation circuit 83f ₃ A one-second timer 83f that generates a "1" level output signal when the value exceeds a value representing seconds, a load determination circuit 83h, a register 83i, a falling memory circuit 83j, inverters 83k to 83m, a heavy load counter 83p, a light load It consists of a counter 83q and a delay circuit 83r. Counters 83p and 83q set "1" to terminal C.
When a level signal is supplied, the count value is counted up, and when a signal is supplied to the terminal R, the count value is reset. The load determination circuit 83h determines whether the load is light, medium, or
Judgments are now divided into three levels of severity.

[Table] Note that when the power is turned on, the register 83i is unconditionally set to the medium load state. The intermediate flow rate signal generation circuit 89 includes a 3-second clock counter 89a, AND circuits 89b to 89f, inverters 89g to 89h, OR circuits 89i to 89k,
It consists of a load change storage circuit 89l and a delay circuit 89m. And 3 seconds clock counter 8
In 9a, a down count is performed every time a signal is supplied to the terminal CD, and an up count is performed every time a signal is supplied to the terminal CU, but the counted value does not exceed "5". It is configured as follows. Further, this counter 89a outputs a signal at the "0" level when the count value is "4" or less, and outputs a signal at the "1" level when the count value is 5. Note that the oil flow rate setting circuit 87 processes the supplied signals based on the priorities and conditions shown in Table 2.

[Table] Furthermore, when the oil flow rate setting circuit 87 receives a signal with priority level 2, when the signal supplied to the terminal 87b is at the "1" level, the oil flow rate is controlled to an intermediate flow rate, and the signal supplied to the terminal 87b is When the signal is at the "0" level, the oil flow rate is controlled to a fixed flow rate. The operation of the device configured in this way is as follows. First, normal operation will be explained. When the automobile starts running, an instantaneous vehicle speed calculation circuit 8 is generated based on the vehicle speed signal generated from the vehicle speed signal generation circuit 1.
The instantaneous vehicle speed is calculated at 0. The operation at this time is the second
This will be explained using figures. When the vehicle speed signal shown in FIG. 2a is generated from the vehicle speed signal generating circuit 1, this signal is sent to the clock counter 80b via the OR circuit 80a.
clock counter 8.
0b is reset each time a vehicle speed signal is generated.
Then, when the reset is released, the clock counter 80b counts up the reference signal supplied to the terminal C every 1 millisecond. On the other hand, since the vehicle speed signal is supplied to the fall detection circuit 83d of the load detection circuit 83, the fall detection circuit 83d generates a pulse every time the vehicle speed signal falls, as shown in FIG. 2c. Fall detection circuit 83
The pulse generated at time d is supplied to the falling memory circuit 83j and is also supplied to the terminal R of the counter 83f1 of the ₁ -second timer 83f, so the falling memory circuit 83j is supplied to the falling memory circuit 83j as shown at time t1 in FIG. 2e. Sends a signal of "1" level as follows, and 1 second timer 83f
Since the counter _83f1 is reset,
It sends out a "0" level signal as shown in .
(In this case, there is no change in level since it is at the "0" level even before the reset.) Since the reference signal with a period of 1 millisecond is supplied to the terminal C of the counter 83f ₁ in the 1-second timer 83f, the counter 83f ₁
When the reset is released, the reference signal is counted and counted up. Then, when a time of 1 second or more has elapsed from the time when the reset was released, the count value of the counter _83f1 of the 1-second timer 83f is changed to the comparator 83.
Since it is larger than the "constant" 83f ₃ , which indicates that the elapsed time supplied to f ₂ has reached 1 second,
The one-second timer 83f begins to send out a signal at the "1" level, as shown at time _t2a in FIG. 2d. As a result, a signal at the "1" level is supplied to the terminal R of the falling memory circuit 83j, so that the output signal of the falling memory circuit 83j is at the "1" level as shown at time _t2a in FIG. 2e. The level is "0". The output signal of the falling memory circuit 83j is inverted in different phases by the inverter 83m, becomes the "1" level, and is supplied to the instantaneous vehicle speed calculation circuit 80, thereby resetting the clock counter 80b and the register 80c. Next, when the vehicle speed signal is supplied at time t2, the fall detection circuit 83d of the load detection circuit 83 generates the pulse shown in FIG. Become. If the cycle of the vehicle speed signal supplied during the period from time t2 to time t7 is less than a predetermined period T1 (set to 1 second in this example), the register 80c is set to the second and subsequent rising edges of the vehicle speed signal. At each downlink time, the clock counter 80b at that time
The counting results are taken in and outputted as shown in FIG. 2f. However, since the period between time points t7 and t8 is 1 second or more, when 1 second or more has elapsed from the falling point of time t7, the 1-second timer 83f begins to send out a "1" level signal as shown in d. . As a result, the falling memory circuit 83j sends out a "0" level signal as shown in e, so the clock counter 80b and register 80c of the instantaneous vehicle speed calculation circuit 80 are reset, and the register 80c is reset.
The output signal of is at the "0" level as shown at f. At time t8, the vehicle speed signal is supplied again, so the 1-second timer 83f and falling detection circuit 8
A state change occurs at 3j, but since the period between time t8 and t9 is more than 1 second, register 80c
During this period, the output signal does not change. In this way, when the instantaneous vehicle speed calculation circuit 80 is repeatedly supplied with a vehicle speed signal with a period of less than 1 second, the clock counter 80b calculates the count result every time the vehicle speed signal falls after the second falling point of the vehicle speed signal. is output as instantaneous vehicle speed. However, when the vehicle speed signal period exceeds 1 second, the clock counter 80b and register 80c are reset. The vehicle speed signal calculated in this manner is supplied to the oil flow rate decoder 85. The oil flow decoder 85 is composed of a ROM in which oil flow characteristics corresponding to the vehicle speed as shown in FIG. is read out and the signal is supplied to the oil flow rate setting circuit 87. The oil flow characteristics written in the oil flow decoder 85 differ depending on whether the load is large, medium, or small, and also depending on whether the road you are driving on is in the city, in the suburbs, or on a highway. It is necessary to store all necessary oil flow characteristics accordingly. For example, as shown in the symbols S=1 to S=5 in FIG.
Type. Normally, all of the characteristics shown in FIG. 4 should be stored, but here, only one type of characteristics with S=3 is stored. As a result, the oil flow decoder 85 outputs a signal representing the oil flow control amount corresponding to the instantaneous vehicle speed at S=3 in FIG.
The read signal is read out according to the characteristics shown by and is supplied to the oil flow rate setting circuit 87. Since the vehicle speed signal is also supplied to the average vehicle speed calculation circuit 81, the vehicle speed counter 81a of the average vehicle speed calculation circuit 81 counts up each time the vehicle speed signal is supplied. Then, every 30 seconds, the reference signal generation circuit 88
Since the reference signal is supplied from the register 81c, each time the reference signal is supplied, the register 81c takes in the count value of the vehicle speed counter 81a up to that point. Then, the reference signal is delayed by an appropriate time, for example, about 1 microsecond, in the delay circuit 81b and then supplied to the terminal R of the vehicle speed counter 81a, so that the vehicle speed counter 81a is reset. When the reset is released, the vehicle speed counter 81a starts counting the vehicle speed signal again. Therefore, the count value of the vehicle speed signal for 30 seconds is sent out as an average vehicle speed signal from the register 81c, and is supplied to the driving condition decoder 84. Similarly, the steering signal output from the steering signal generation circuit 2 is calculated by the average steering amount calculation circuit 82, and the count value of the steering signal every 30 seconds is sent to the driving condition decoder 8 as the average steering signal.
4. The driving condition decoder 84 decodes whether the vehicle is traveling in an urban area, in the suburbs, or on an expressway, and has written therein characteristics with average vehicle speed and average steering amount as variables, as shown in FIG. Ta
Since the driving condition decoder 84 is constituted by a ROM, when the average vehicle speed and the average steering amount are supplied, the driving condition decoder 84 reads the driving condition and supplies a signal representing the driving condition to the control pattern decoder 86. In addition, in FIG. 5, area A represents an urban driving area where the average vehicle speed is below a medium level and the area where the value is small has a wide average steering amount distribution, and the higher the average vehicle speed, the smaller the average steering amount distribution. In Area B, the average vehicle speed is medium, but in the parts where the value is small, the average steering amount is distributed in a range of relatively large values, and as the average vehicle speed increases, the average steering amount distribution range becomes wider. It represents an area. Area C represents a high-speed driving area where the average vehicle speed is high regardless of the average steering amount. In Figure 5,
M=1, M=2 written in areas A, B, C,
M=3 is a variable that differs depending on the driving area used when correcting the oil flow rate, which will be described later. On the other hand, the load detection circuit 83 includes the heavy load detection circuit 3,
Signals are supplied from the light load detection circuit 4 and the vehicle speed signal generation circuit 1, and a load signal is generated according to the state of each signal, and this load signal is supplied to the control putter decoder 86 and the intermediate flow rate setting circuit 89. There is. When a "0" level signal is generated from either the heavy load detection circuit 3 or the light load detection circuit 4, the load detection circuit 86 inverts the signal with the inverter 83k or 83l and outputs the AND circuit 83a.
or 83b, this signal is supplied to the heavy load counter 83p or 83q every 10 milliseconds and counted. This count value is determined by the load determination circuit 83h, and the data of the determination result is supplied to the terminal D of the register 83i. Then, when a signal generated every 10 seconds from the reference signal generation circuit 88 is supplied to the terminal C of the register 83i, the load determination result is taken into the register 83i. At this time, the signals sent out from the register 83i have the values shown in Table 3 depending on the load state. Further, since the signal generated every 10 seconds from the reference signal generation circuit 88 is supplied to the heavy load counter 83p and the light load counter 83q via the delay circuit 83r, these counters are reset every 10 seconds and new data is generated. will be counted.

[Table] The running condition signal and load signal obtained in this way are supplied to the control pattern decoder 86, and calculations are performed according to the standard of equation (1) shown below.
The control pattern decoder 86 supplies the calculated correction signal to the oil flow rate setting circuit 87. C=M+L...(1) However, the definition of each symbol is as follows. C: Correction signal M: Running condition signal L: Load signal As a result, the correction signal C takes into account both the running condition and the load state. In addition to the correction signal C, the oil flow rate setting circuit 87 is supplied with a signal representing the oil flow rate q determined by the characteristic S=3 in FIG. 4 read out from the oil flow rate decoder 85 and the vehicle speed. shown in
A control signal for controlling a power steering device (not shown) is sent out according to the standard of equation (2). Q=q+A(C-3)...(2) However, the definition of each symbol is as follows. Q: Control signal q: Signal that controls the oil flow rate read from the reference characteristics A: Assuming that the characteristics shown in Fig. 4 are equally spaced,
The value representing the interval The reference characteristic is selected as S=3 in Fig. 4 as mentioned above, so if the running condition is M=1 and the load signal is L=1, the correction signal is calculated from equation (1). C=2, and the control signal becomes Q=q-A from equation (2). For this reason, the characteristic of S=2 in FIG. 4 is selected. Similarly, if M=1 and L=0, Q=q-2A, and the characteristic of S=1 in FIG. 4 is selected. As described above, since the reference characteristic is shifted depending on the operating conditions, only one type of characteristic stored in the oil flow rate decoder 85 can perform power steering suitable for all operating conditions. The signal output from the oil flow rate setting circuit 87 is converted into an analog voltage by the D/A converter 5, and this analog voltage is controlled by the solenoid coil drive circuit 6 to adjust the duty ratio according to the magnitude of the analog voltage. is converted into a solenoid coil drive signal. As a result, the solenoid coil 7 supplies the amount of oil corresponding to the duty ratio to the power steering device (not shown), so that power steering is performed in accordance with the operating conditions. The above is the normal operation, but the operation when there is a failure in which output signals are no longer generated from each sensor from the vehicle speed signal generation circuit 1 to the light load detection circuit 4 is as shown in Table 4 below. In Table 4, the ◯ mark indicates a state in which the sensor is normally generating a signal, and the x mark indicates a state in which the sensor is not generating a signal.

〔Effect of the invention〕

As explained above, when the control device for the power steering device according to the present invention controls the oil flow rate according to the signals supplied from the vehicle speed sensor, the steering sensor, and the load sensor, the failure of the vehicle speed sensor is caused by the failure of the vehicle speed sensor. Since the oil flow rate is controlled to an intermediate flow rate when the signal changes, the steering force does not fluctuate excessively as in the conventional case, so there is an effect that safe driving can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is an instantaneous vehicle speed calculation circuit 8 in FIG.
Figure 3 is a graph showing representative characteristics of vehicle speed and oil flow rate, Figure 4 is a graph showing characteristics of vehicle speed and oil flow rate determined by driving conditions, and Figure 5 is a graph showing characteristics of vehicle speed and oil flow rate. A graph showing the characteristics of the average steering amount distribution, Fig. 6 is a waveform diagram of each part to explain the switching state of oil flow rate, Fig. 7 is a diagram showing an example of the device shown in Fig. 1 configured with a microcomputer, Fig. Figure 8 is a diagram showing the structure of a disc and magnet for generating a vehicle speed signal, Figure 9a is a cross-sectional view of the steering shaft portion with a photo interrupter attached to the steering signal generation circuit, and Figure 9b is a slit disc. FIG. 10 is a perspective view showing a load sensor configured with attached photo interrupters for a heavy load detection circuit and a light load detection circuit, and FIG. 11 is a flowchart showing the operation of the device shown in FIG. 7. It's a chat. DESCRIPTION OF SYMBOLS 1... Vehicle speed signal generation circuit, 2... Steering signal generation circuit, 3... Heavy load detection circuit, 4... Light load detection circuit, 8... Control circuit, 80... Instantaneous vehicle speed calculation circuit, 81... Average Vehicle speed calculation circuit, 82... Average steering amount calculation circuit, 83... Load detection circuit, 83a,
83b...gate circuit, 83c...AND circuit, 8
3d...Rise detection circuit, 83e...Rise and fall detection circuit, 83f...1 second timer, 83
h...Load judgment circuit, 83i...Register, 84
...Running condition decoder, 85...Oil flow rate decoder, 86...Control pattern decoder, 87...
Oil flow rate setting circuit, 88...Reference signal generation circuit, 89...Intermediate flow rate signal generation circuit, 90...Comparison circuit.

Claims (1)

[Claims] 1. In a control device for a power steering device that controls oil flow rate according to signals supplied from a vehicle speed sensor, a steering sensor, and a load sensor, when the signal from the load sensor changes when the vehicle speed sensor fails. A control device for a power steering device characterized by controlling an oil flow rate to an intermediate flow rate.