JP3593922B2 - Monitoring device for actuator drive circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for monitoring the operation of an actuator drive circuit that intermittently applies a drive voltage to an actuator according to a duty ratio calculated for each control cycle.
[0002]
[Prior art]
2. Description of the Related Art An actuator driving circuit that drives an actuator such as a motor or a solenoid by intermittently applying a driving voltage in each control cycle is known. This type of actuator drive circuit is also called a pulse drive circuit or a duty drive circuit because the actuator is driven by changing the duty ratio of the drive voltage for each control cycle from 0 to 100%.
[0003]
For example, when driving a negative pressure type throttle actuator of a vehicle having a DC motor and a solenoid, as shown in FIG. 9, the ON period is 100 msec from the beginning during the control cycle T (= 150 msec), and the ON period thereafter. The OFF period is 50 msec. Here, the ON period is a period during which the application of the drive voltage to the motor and the solenoid is permitted, and the OFF period is a period during which the application of the drive voltage to the motor and the solenoid is prohibited. Therefore, in the drive circuit of the conventional vehicle throttle actuator, the duty ratio is limited to a maximum of 66.7%.
[0004]
In the conventional drive circuit for a throttle actuator for a vehicle, 50 msec, which is 1/3 of the control cycle T (= 150 msec), is set as the OFF period. In this OFF period, the output of the drive circuit is turned off, that is, the drive voltage becomes 0. Therefore, the operation of the drive circuit is monitored by setting the last 20 msec of the 50 msec OFF period as the monitoring period. That is, when a voltage is generated at the drive terminals of the motor and the solenoid even though the output is turned off during the OFF period, there is some abnormality in the drive circuit, and appropriate fail-safe processing is performed.
[0005]
[Problems to be solved by the invention]
However, in the conventional actuator drive circuit monitoring device, a constant OFF period is forcibly provided for each control cycle in order to monitor the operation of the drive circuit, so that the maximum value of the duty ratio is limited to a low value. As a result, there is a problem that the actuator cannot be driven at a duty ratio of 100% or close thereto.
[0006]
Therefore, if the duty ratio is increased by lengthening the ON period and shortening the OFF period, the voltage at the drive terminal is immediately increased due to the back electromotive voltage generated immediately after the motor or solenoid is turned off as shown in FIG. There is a problem that the counter electromotive voltage is not recognized as 0 and is erroneously recognized as the output voltage of the drive circuit, and that the drive circuit is determined to be abnormal even though it is normal.
[0007]
If the control cycle T is to be shortened from the current 150 msec in order to improve the control response of the throttle actuator, the drive circuit is normally affected by the back electromotive voltage of the motor and the solenoid as in the case of increasing the duty ratio. In some cases, an abnormality determination is made in spite of the above.
[0008]
An object of the present invention is to correctly monitor the operation of an actuator drive circuit regardless of a control cycle and a duty ratio.
[0009]
[Means for Solving the Problems]
The present invention will be described with reference to FIG. 1 showing a configuration of an embodiment.
(1) The invention according to claim 1 is an actuator drive circuit Tr1, Tr2, Tr3 for intermittently applying a drive voltage to the actuators 31a, 32a, 33a in accordance with a duty ratio calculated for each predetermined control cycle, and an actuator 31a. Circuits (R1, R2), (R3, R4), (R5, R6) for detecting the potentials of the drive terminals TB1, TB2, TB3 of, 32a, 33a, and a control cycle with a duty ratio of 0% Is detected within a period including the end point of the control cycle within the control cycle and shorter than the control cycle. A determination circuit 10 is provided for determining whether the operation of the actuator drive circuits Tr1, Tr2, Tr3 is normal based on the detection potentials of the detection circuits (R1, R2), (R3, R4), (R5, R6).
(2) In the actuator drive circuit monitoring device according to the second aspect, when the control cycle in which the duty ratio is greater than 0% and less than 100% continues for a predetermined N1 times, the duty ratio of the next control cycle is changed. A first control circuit 10 is forcibly set to 0%.
(3) When the control cycle of the duty ratio of 100% continues for a predetermined N2 times continuously, the duty ratio of the next control cycle is forcibly set to 0%. A second control circuit 10 is provided.
(4) In the monitoring device for an actuator drive circuit according to a fourth aspect, the number of times N2 is set to be smaller than the number of times N1.
(5) The actuator drive circuit monitoring device according to claim 5, wherein the actuator drive circuits Tr1, Tr2 and Tr3 are circuits for driving the vacuum pump motor 31a, the vent valve solenoid 32a and the safety valve solenoid 33a of the negative pressure type throttle actuator of the vehicle. It is what it was.
[0010]
In the section of the means for solving the problems described above, a diagram of one embodiment is used for easy understanding of the description, but the present invention is not limited to the embodiment.
[0011]
【The invention's effect】
(1) According to the first aspect of the invention, when monitoring the operation of the actuator drive circuit that intermittently applies the drive voltage to the actuator according to the duty ratio calculated for each predetermined control cycle, the duty ratio is set to 0. % Control cycle Is detected within a period including the end point of the control cycle within the control cycle and shorter than the control cycle. Whether the operation of the actuator drive circuit is normal or not is determined based on the detected potential of the actuator drive terminal. Therefore, even if the control cycle is shortened or the duty ratio is increased, the motor or solenoid can be counteracted. The operation of the actuator drive circuit can be correctly monitored without being affected by the voltage.
(2) According to the second aspect of the present invention, when a control cycle in which the duty ratio is greater than 0% and less than 100% continues for a predetermined N1 times, the duty ratio of the next control cycle is forcibly set. Since it is set to 0%, in addition to the above effect of claim 1, even if a control cycle in which the duty ratio is not 0% continues due to the load condition, the operation of the actuator drive circuit can be monitored at appropriate time intervals. In addition, it is possible to avoid a state where the operation cannot be monitored for a long time.
(3) According to the third aspect of the invention, when the control cycle of the duty ratio of 100% continues for a predetermined N2 times, the duty ratio of the next control cycle is forcibly set to 0%. Therefore, in addition to the effect of the first aspect, the operation of the actuator drive circuit is monitored at an appropriate time interval even if the control cycle with the duty ratio of 100% continues due to the high load condition or the disconnection of the power supply circuit of the drive circuit. It is possible to avoid a state in which the operation cannot be monitored for a long time.
(4) According to the invention of claim 4, a situation in which a control cycle with a duty ratio of 100% continues continuously for a long time is high in urgency, so that the monitoring time interval for such a situation can be shortened. And take appropriate measures.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment in which the present invention is applied to an actuator drive circuit of a negative pressure type throttle actuator for a vehicle will be described. The present invention is not limited to an actuator drive circuit of a throttle actuator for a vehicle, but can be applied to a drive circuit of another actuator for a vehicle or a drive circuit of an actuator other than a vehicle.
[0013]
1 and 2 show the configuration of an embodiment.
First, in FIG. 2, a vacuum pump 31, a vent valve 32, and a safety valve 33 are connected to the negative pressure type throttle actuator 30. The vacuum pump 31 drives a diaphragm 31b by a motor 31a to generate a negative pressure in a negative pressure chamber 30a of the actuator 30. The vent valve 32 and the safety valve 33 are driven by solenoids 32a and 33a, respectively, to release the negative pressure in the negative pressure chamber 30a to atmospheric pressure. That is, the negative pressure in the negative pressure chamber 30a is controlled by the vacuum pump 31, the vent valve 32, and the safety valve 33, and the diaphragm 30b moves right and left in the drawing according to the negative pressure. The movement of the diaphragm 30b is transmitted to a throttle valve (not shown) via an accelerator wire 30c, and the throttle valve is opened and closed. The vacuum pump motor 31a, the vent valve solenoid 32a, and the safety valve solenoid 33a are driven by the control unit 1 shown in FIG.
[0014]
Next, in FIG. 1, the control unit 1 includes a microcomputer 10, a transistor Tr1 for driving a vacuum pump motor 31a, a transistor Tr2 for driving a vent valve solenoid 32a, a transistor Tr3 for driving a safety valve solenoid 33a, and an actuator driving circuit. Monitor circuits (R1, R2), (R3, R4), (R5, R6) for monitoring the operation of the transistors Tr1 to Tr3, and a transistor Tr4 and a relay for shutting off the drive power of the motor 31a and the solenoids 32a, 33a in the event of an abnormality Ry1 and the like.
[0015]
The microcomputer 10 includes a memory and an interface, and executes a control program to be described later to drive the vacuum pump motor 31a, the vent valve solenoid 32a, and the safety valve solenoid 33a, and to operate the actuator drive circuits (Tr1 to Tr3). Monitor.
[0016]
The microcomputer 10 monitors the potential of the drive terminal TB1 of the motor 31a driven by the transistor Tr1 via the monitor circuit (R1, R2). Similarly, the potential of the drive terminal TB2 of the solenoid 32a driven by the transistor Tr2 is monitored via the monitor circuit (R3, R4), and the potential of the drive terminal TB3 of the solenoid 33a driven by the transistor Tr3 is monitored. , R6). The drive terminals TB1 to TB3 are at a low level when the transistors Tr1 to Tr3 are turned on and the motor 31a and the solenoids 32a and 33a are driven, and when the transistors Tr1 to Tr3 are off, that is, the motor 31a and the solenoid 32a. , 33a are at a high level when not driven.
[0017]
The power supply cutoff circuit (Tr4, Ry1) is controlled by the microcomputer 10, and cuts off the drive power supplied from the vehicle-mounted battery BAT to the motor 31a and the solenoids 32a, 33a via the ignition key switch SW1.
[0018]
The main switch SW2, set switch SW3, accelerate switch SW4, coast switch SW5, cancel switch SW6, brake switch SW7, brake switch SW7, vehicle speed sensor 2, throttle sensor 3, engine rotation sensor 4, etc. are connected to the microcomputer 10 of the control unit 1. Is done.
[0019]
The main switch SW2 is a switch for starting or stopping a vehicle speed control device (not shown). The set switch SW3 is a switch for starting the constant speed traveling control and setting the vehicle speed. The accelerate switch SW4 is a switch for instructing an increase in the target vehicle speed, and the coast switch SW5 is a switch for instructing a decrease in the target vehicle speed. The cancel switch SW6 is a switch for canceling the constant speed traveling control, and the brake switch SW7 is a switch that operates when a foot brake is operated. When the brake switch SW7 is operated, the constant speed traveling control is released in the same manner as when the cancel switch SW6 is operated. Since the vehicle speed control device is not directly related to the present invention, a detailed description is omitted.
[0020]
Further, the vehicle speed sensor 2 generates a pulse signal for each predetermined traveling distance of the vehicle, and can count the number of generated pulses in a predetermined time to detect the traveling speed of the vehicle. The throttle sensor 3 detects the actual opening of the throttle. Further, the engine rotation sensor 4 generates a pulse signal for each predetermined rotation angle of the engine, and can detect the engine rotation speed by counting the number of generated pulses in a predetermined time.
[0021]
In this embodiment, the control cycle T and the duty ratio of the motor 31a and the solenoids 32a and 33a are arbitrarily set, and the operation of the actuator drive circuits (Tr1 to Tr3) is monitored by the following method. Since the motor 31a, the solenoid 32a, and the solenoid 33a are separately driven by the transistors Tr1 to Tr3, the operation monitoring of the actuator driving circuits is also performed separately. However, all the actuator driving circuits are also monitored by the same monitoring method. Therefore, a description will be given below by taking the drive circuit (transistor Tr1) of the motor 31a as an example.
[0022]
First, when the duty ratio D of the motor 31a calculated by the vehicle speed control device (not shown) is 0%, the last predetermined period of the control cycle T is set as a monitor period Tm as shown in FIG. The operation of the drive circuit (Tr1) of the motor 31a is monitored.
[0023]
When the duty ratio D is 0%, the control cycle T is an OFF period, the drive circuit (Tr1) is turned off, and the motor 31a is not driven. That is, the drive terminal TB1 of the motor 31a should be at the high level. If the drive terminal TB1 of the motor 31a is at the low level in the control cycle T in which the entire period is the OFF period, for example, the transistor Tr1 of the drive circuit has failed and remains on, or It is considered that some abnormality has occurred in the actuator drive circuit, such as a short circuit of the wiring from the drive terminal TB1 to the motor 31a to the vehicle body.
[0024]
Therefore, during the monitoring period Tm, the potential of the drive terminal TB1 is detected via the monitor circuit (R1, R2). If the level is high, the drive circuit of the motor 31a is normal, and if the level is low, there is some abnormality. Can be determined. When it is determined that an abnormality has occurred, the power supply to the motor 31a and the solenoids 32a and 33a is cut off by the power cutoff circuit (Ry1, Tr4).
[0025]
In normal vehicle speed control, a control cycle in which the duty ratio becomes 0% occurs at an appropriate frequency and interval that is not too long in monitoring the operation of the actuator drive circuit in some cycles of the control cycle. . Therefore, there is no problem even if the off period is forcibly provided for each control cycle as in the related art, and the operation of the actuator drive circuit is not monitored during the off period.
[0026]
However, it is necessary to consider that the duty ratio does not become 0% for a long time, and that an unfavorable state occurs in monitoring the operation of the actuator drive circuit. Therefore, in the second monitoring method, when the control cycle T whose duty ratio is greater than 0% and less than 100% continues for a predetermined number of times N1, the next control cycle T is forcibly set as the OFF period, and the control is performed. During the last monitoring period Tm of the cycle, the operation of the actuator drive circuit is monitored.
[0027]
The second monitoring method will be described in detail with reference to FIG. 4. If the duty cycle D is greater than 0% and less than 100% N1 times before the time t1, the next control cycle T ( At t1 to t2), the duty ratio D is forcibly set to 0%, and the actuator drive circuit (Tr1) is turned off. Then, the potential of the drive terminal TB1 of the motor 31a is detected via the monitor circuit (R1, R2) during the monitor period Tm of the control cycle T (t1 to t2). Since the actuator drive circuit (Tr1) is turned off, the drive terminal TB1 is at a high level if the actuator drive circuit is normal, and the drive terminal TB1 is at a low level if the actuator drive circuit has an abnormality as described above. . When the abnormality is determined, the fail-safe processing as described in the first monitoring method is performed. The predetermined number N1 may be set to an appropriate number for monitoring the operation of the actuator drive circuit through experiments or the like.
[0028]
On the other hand, when the line for supplying power to the motor 31a and the solenoids 32a and 33a is broken, or when the ignition key switch SW1 or the power cutoff circuit (Tr4, Ry1) fails and opens, the motor 31a, the solenoid 32a, Since all 33a are turned off, the throttle actuator 30 operates in a direction to close a throttle valve (not shown). For this reason, the deviation between the target vehicle speed and the actual vehicle speed in the vehicle speed control sharply increases, and finally, the duty ratio of 100% is calculated to drive the throttle actuator 30 to drive the throttle valve in the opening direction. In such a case, the control cycle of the duty ratio of 100% continues continuously, and it becomes impossible to monitor the operation of the actuator drive circuit for a long time. On the other hand, even in the normal vehicle speed control, the case where the control cycle with the duty ratio of 100% continues may occur, although very rarely.
[0029]
Therefore, in the third monitoring method, when the control cycle T having a duty ratio of 100% continues for a predetermined number of times N2, the next control cycle T is forcibly set to the OFF period, and in the last monitoring period Tm of the period. Monitor the operation of the actuator drive circuit.
[0030]
The third monitoring method will be described in detail with reference to FIG. 5. If the control cycle T with a duty ratio of 100% continues N2 times before time t3, the duty cycle D will be increased in the next control cycle T (t3 to t4). Is forced to 0%, and the actuator drive circuit (Tr1) is turned off. Then, the potential of the drive terminal TB1 of the motor 31a is detected via the monitor circuit (R1, R2) in the monitor period Tm of the control cycle T (t3 to t4). Since the actuator drive circuit (Tr1) is turned off, the drive terminal TB1 is at a high level when the actuator drive circuit is normal, and the drive terminal TB1 is at a low level when the actuator drive circuit has an abnormality as described above. . If an abnormality is determined, fail-safe processing is performed. However, if there is a disconnection failure in the power supply circuit, power-off of the actuator drive circuit is not an effective processing, and other appropriate processing including an alarm is performed.
[0031]
In the third monitoring method, an abnormal situation with higher urgency is monitored than in the above-described second monitoring method. Therefore, the predetermined number N2 is set to a value smaller than N1, for example, three times.
[0032]
In this embodiment, even if the control cycle T is shortened or the duty ratio D is increased, the operation of the motor or the solenoid is monitored by monitoring the operation of the actuator drive circuit by the above-described first to third methods. The operation of the actuator drive circuit can be correctly monitored without being affected by the back electromotive voltage. In addition, even if a high load condition or a power failure occurs in which a control cycle in which the duty ratio is not 0%, particularly a control cycle in which the duty ratio is 100%, continues, the operation of the actuator drive circuit is monitored at appropriate time intervals. And take appropriate measures.
[0033]
6 to 8 are flowcharts showing drive control of the throttle actuator and a monitor program of the drive circuit. The operation of the embodiment will be described with reference to these flowcharts. These programs are executed for each of the vacuum pump motor 31a, the vent valve solenoid 32a, and the safety valve solenoid 33a. However, since all of the operations are the same, the vacuum pump motor 31a will be described below as an example. explain.
[0034]
The microcomputer 10 of the control unit 1 executes a main program shown in FIG. 6 every predetermined control cycle T. In step 1, the drive control routine shown in FIG. 7 is executed to control the drive circuit of the motor 31a.
[0035]
In step 11 of FIG. 7, the duty ratio D of the motor 31a is calculated by a vehicle speed control device (not shown). It is confirmed whether or not the duty ratio D calculated in the subsequent step 12 is 0%. In the case of D = 0%, it is not necessary to turn on the transistor Tr1 of the actuator drive circuit, so that the program returns to the main program. If the duty ratio D is not 0%, the process proceeds to step 13, and it is confirmed whether the calculated duty ratio D is 100%.
[0036]
If the duty ratio D is 100%, the process proceeds to step 14, and it is determined whether the control cycle T with the duty ratio of 100% has continued N2 times, for example, three times, before the previous control cycle T. If the control cycle T with a duty ratio of 100% has continued N2 times, the process proceeds to step 16, and the duty ratio D in the current control cycle T is forcibly set to 0%. Then, in this case, since it is not necessary to turn on the transistor Tr1 of the actuator drive circuit, the process returns to the main program. On the other hand, if the number of times of the control cycle T with the duty ratio of 100% is less than N2 in step, the process proceeds to step 17, and the transistor Tr1 is controlled with the duty ratio of 100%. That is, the transistor Tr1 is kept turned on during the entire period of the current control cycle T.
[0037]
If the duty ratio D is 0 <D <100%, the process proceeds from step 13 to step 15 to determine whether the control cycle T having a duty ratio greater than 0% and less than 100% has continued N1 times before the previous control cycle T. Check. If the control cycle of the duty ratio of 0 <D <100% has been continued N1 times, the process proceeds to step 16, and the duty ratio D in the current control cycle T is forcibly set to 0%. Then, in this case, since it is not necessary to turn on the transistor Tr1 of the actuator drive circuit, the process returns to the main program. On the other hand, if the number of control cycles T of 0 <D <100% is less than N1 in step 15, the process proceeds to step 17, and the transistor Tr1 is controlled with the duty ratio D calculated this time. Then, the process returns to the main program.
[0038]
In step 2 of FIG. 6 after the execution of the drive control routine, the drive circuit monitoring routine shown in FIG. 8 is executed. In step 21 of FIG. 8, it is checked whether the duty ratio D in the current control cycle T is 0%. If the duty ratio D is not 0%, the operation of the actuator drive circuit cannot be monitored, and the process returns to the main program.
[0039]
If the duty ratio D of the current control cycle T is 0%, the process proceeds to step 22 and waits until a predetermined monitoring period Tm set at the end of the control cycle T shown in FIG. Note that the monitoring period Tm is set to the last predetermined period of the control cycle T when the duty ratio in the previous control cycle T is 100%, from the beginning of the current control cycle T or earlier. When the operation of the actuator drive circuit is monitored by detecting the potential of the drive terminal TB1 of the motor 31a, the monitor period Tm is set at the end of the control cycle T at which the influence of the back electromotive voltage of the motor and the solenoid is eliminated. Set.
[0040]
When the monitoring period Tm is reached, the process proceeds to step 23, where it is determined whether the output port connected to the base of the transistor Tr1 is at a low level, that is, whether the drive command for the transistor Tr1 is turned off, and the drive command is turned off. If not, the process returns to the main program without monitoring the operation of the actuator drive circuit. If the drive command for the transistor Tr1 is off, the process proceeds to step S24, and it is checked by the monitor circuit (R1, R2) whether the drive terminal TB1 of the motor 31a is at a high level. Since the duty ratio D of the current control cycle T is 0% and the drive command for the transistor Tr1 is off, the drive circuit Tr1 of the motor 31a should be off, and therefore the motor 31a The drive terminal TB1 must be at a high level. If the drive terminal TB1 is at the high level, the operation of the drive circuit of the motor 31a is determined to be normal, and the process returns to the main program.
[0041]
On the other hand, if the drive terminal TB1 of the motor 31a is at a low level, it is determined that there is some abnormality in the drive circuit of the motor 31a, and the process proceeds to step S25. In step 25, in order to cope with the abnormality of the actuator drive circuit, the power supply to the motor 31a is cut off by the power cutoff circuit (Tr4, Ry1), and a warning and a warning are issued.
[0042]
In the above-described embodiment, a motor and a solenoid have been described as examples of the actuator, but the actuator is not limited to the motor and the solenoid.
[0043]
Further, the actuator drive circuit and the monitor circuit are not limited to the circuit shown in FIG. 1 of the above-described embodiment.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment.
FIG. 2 is a diagram illustrating a configuration of an embodiment following FIG. 1;
FIG. 3 is a diagram for explaining a relationship between a control cycle T and a monitoring period Tm.
FIG. 4 is a diagram for explaining a second monitoring method.
FIG. 5 is a diagram for explaining a third monitoring method.
FIG. 6 is a flowchart showing a main program according to one embodiment.
FIG. 7 is a flowchart illustrating a drive control routine according to one embodiment.
FIG. 8 is a flowchart illustrating a drive circuit monitoring routine according to one embodiment.
FIG. 9 is a diagram for explaining a conventional method of monitoring an actuator drive circuit.
FIG. 10 is a diagram for explaining the effect of the back electromotive voltage of the motor and the solenoid when the duty ratio is increased or the control cycle is shortened in the conventional actuator drive circuit monitoring method.
[Explanation of symbols]
1 control unit
10 Microcomputer
Tr1 to Tr2 Transistor (actuator drive circuit)
(R1, R2), (R3, R4), (R5, R6) Monitor circuit
(Tr4, Ry1) Power cutoff circuit
BAT battery
SW1 ignition key switch
30 Negative pressure type throttle actuator
31a Vacuum pump motor
32a Vent valve solenoid
33a Safety valve solenoid

Claims (5)

An actuator drive circuit that intermittently applies a drive voltage to the actuator according to a duty ratio calculated for each predetermined control cycle,
A detection circuit for detecting a potential of a drive terminal of the actuator,
The operation of the actuator drive circuit is performed based on a detection potential detected by the detection circuit within a period including the end point of the control cycle in a control cycle having a duty ratio of 0% and shorter than the control cycle. A monitoring circuit for an actuator drive circuit, comprising: a determination circuit for determining whether the operation is normal. The monitoring device for an actuator drive circuit according to claim 1,
A first control circuit for forcibly setting the duty ratio of the next control cycle to 0% when a control cycle in which the duty ratio is greater than 0% and less than 100% continues for a predetermined number of N1 times. A monitoring device for an actuator drive circuit, characterized in that: A monitoring device for an actuator drive circuit according to claim 1 or 2,
An actuator drive circuit comprising a second control circuit for forcibly setting the duty ratio of the next control cycle to 0% when the control cycle of the duty cycle of 100% continues for a predetermined number of N2 times. Monitoring device. The monitoring device for an actuator drive circuit according to claim 3,
A monitoring device for an actuator drive circuit, wherein N2 is set to a number smaller than N1. A monitoring device for an actuator drive circuit according to any one of claims 1 to 4,
The actuator driving circuit is a circuit for driving a vacuum pump motor, a vent valve solenoid, and a safety valve solenoid of a negative pressure type throttle actuator of a vehicle.

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