JPH069004B2 - Electromagnetic actuator drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention is an electromagnetic actuator that operates by electromagnetic force in response to a pulse command signal having a predetermined duty ratio (hereinafter, simply referred to as an electromagnetic actuator). ) Can be controlled by, for example, an electromagnetic valve using a linear solenoid as an electromagnetic actuator to control the auxiliary air amount and fuel supply amount of the carburetor in the internal combustion engine, or the internal combustion engine The present invention relates to an electromagnetic actuator drive device that can effectively achieve control of the amount of air to the exhaust system and the amount of auxiliary air to the intake system.

[Prior Art] As an electromagnetic actuator drive device that has been invented and proposed in the related art, for example, as shown in "Electromagnetic actuator drive circuit" in Japanese Patent Laid-Open No. 57-121703, electromagnetic operation is proposed. Deviation integration of the difference between the current flowing through the linear solenoid used as a voltage regulator and the analog voltage indicating the target value of the current supplied to the linear solenoid, and the output of this deviation integration and the sawtooth wave generated by the sawtooth wave generation circuit Compare with a comparator and turn on the linear solenoid with the output of this comparator.
There is known a device that is driven off to control a current flowing through a linear solenoid. Further, with the recent progress of microcomputers and the like, most of them use a microcomputer to instruct a target value of a current supplied to a linear solenoid.

[Problems to be Solved by the Invention] However, conventionally proposed electromagnetic actuator driving devices can be precisely controlled so that the current flowing through the electromagnetic actuator approaches a target value instructed by a microcomputer or the like. Although it is an excellent one, there were the following problems. That is, (a) an element that constitutes a sawtooth wave generation circuit or the like is required,
The number of constituent elements increases.

(B) Since the signal representing the target current value supplied to the electromagnetic actuator such as the linear solenoid is an analog signal, it is not suitable for digital signals such as "0" and "1" signals by a microcomputer or the like. Digital-to-analog converter (hereinafter, simply D / A) for converting a signal into an analog signal
Called a converter. ) Etc. are required.

(C) Since the target current value by the microcomputer or the like is output as a signal of a plurality of bits, for example, 8 bits, eight signal lines are required and the circuit becomes complicated.

Therefore, an electromagnetic actuator driving device for a microcomputer having a simple circuit has been desired.

Configuration of the Invention [Means for Solving the Problems] The configuration of the electromagnetic actuator driving device of the present invention for solving the above problems is as follows.

An electromagnetic actuator driving device of the present invention is a switching element that interrupts a current flowing through an electromagnetic actuator that operates by electromagnetic force, a current detection unit that detects a current flowing through the electromagnetic actuator, and a current flowing through the electromagnetic actuator. Has a duty ratio corresponding to the target value of, and has a drive signal receiving means for externally receiving a pulse signal instructing to drive the electromagnetic actuator, a resistor and a capacitor, and detected by the current detecting means. A deviation integrator circuit, which is charged and discharged based on the current and the pulse signal received by the drive signal receiving means, and whose time constant is larger than the cycle of the pulse signal, and the capacitor which changes in the same cycle as the pulse signal. Depending on the polarity of the charging voltage, turn on the switching element
And a switching element control means for performing off control.

Here, the switching element controls the current flowing through the electromagnetic actuator by switching, and may be a highly responsive relay or transistor, or an element such as a thyristor, FET, or diode.

The current detection means is for detecting the current flowing through the electromagnetic actuator, and may be configured to directly detect the current flowing through the electromagnetic actuator, or one that reflects the current flowing through the electromagnetic actuator, For example, it may be configured to indirectly detect the charging time of the capacitor.

The drive signal receiving means is a means for receiving a pulse signal instructing driving of the electromagnetic actuator from a microcomputer or the like, and may be received in a form reflecting the pulse signal,
The pulse signal to be received may be received as it is, or may be received after being converted into some form.

The deviation integration circuit is composed of a resistor and a capacitor connected in series, and operates based on the detection signal detected by the current detection means and the pulse signal received by the drive signal reception means. The time constant that it has is characterized by being larger than the cycle received by the drive signal receiving means.

The switching element control means is a means for controlling a switching element that drives an electromagnetic actuator, and controls on / off of the switching element according to a change in the polarity of the charging voltage of the capacitor of the deviation integration circuit.

[Operation] The electromagnetic actuator drive device of the present invention having the above-described structure operates as follows.

When the pulse signal having the duty ratio corresponding to the target current of the electromagnetic actuator is received by the drive signal receiving means, the integrating circuit is charged and discharged based on the detected current detected by the current detecting means and the pulse signal. , Its polarity is inverted in the same cycle as the pulse signal, and its duty ratio becomes a value corresponding to the deviation between the target current and the detected current.
The switching element control means controls ON / OFF of the switching element according to the polarity of the capacitor of the integrating circuit, and the energization of the electromagnetic actuator is interrupted, and the current value flowing due to the interruption is the duty ratio of the pulse signal. The value is controlled according to. Furthermore, since the charging / discharging time constant of the integrating circuit is set to be larger than the cycle of the pulse signal, the charging voltage of the integrating circuit does not saturate and the duty ratio of the pulse signal is adjusted even when the power supply voltage fluctuates. High-precision current feedback control is performed.

[Examples] Next, examples of the present invention will be described in detail. FIG. 1 is a circuit diagram showing an electromagnetic actuator driving device of an embodiment of the present invention.

The electromagnetic actuator driving device 1 of the present embodiment is roughly composed of a switching circuit for driving an electromagnetic actuator such as a linear solenoid, a current detection circuit 3 for detecting a current flowing through the electromagnetic actuator, and an electromagnetic actuator from a microcomputer or the like. Drive signal receiving circuit 4, which receives a pulse signal instructing the driving of the deviation detection circuit 4, which operates based on the current detected by the current detecting circuit 3 and the pulse signal received by the drive signal receiving circuit 4.
The switching control circuit 6 controls ON / OFF of the switching circuit 2 according to the operation of the deviation integration circuit 5. In this embodiment, as the electromagnetic actuator, the control computer CP is used to supply the linear solenoid SL for controlling the auxiliary air amount of the carburetor in the internal combustion engine and the pulse signal for instructing the driving of the linear solenoid SL. A battery BT is connected via a switch SW to supply power to the linear solenoid SL.

The switching circuit 2 is composed of transistors Tr1 and Tr2 and a resistor R1.
Has a power supply Vcc at its emitter, a switching control circuit 6 at its base, and a transistor T through a resistor R1 at its collector.
Each is connected to the base of r2. The collector of the transistor Tr2 is connected to one end of the linear solenoid SL, and the emitter thereof is connected to the current detection circuit 3. Therefore, when the transistor Tr1 is turned on / off by the output signal of the switching control circuit 6, the transistor Tr2 is turned on / off and the linear solenoid SL is driven by the duty ratio of the on / off signal.

The current detection circuit 3 includes resistors R2, R3, R4, R5, R
6, R7, R8, R9 and R10, a diode D1, and an operational amplifier OP1. One end of the resistor R2 is connected to the collector of the transistor Tr2 of the switching circuit 2, and the other end is connected to the operational amplifier O via the resistor R4.
It is connected to the input minus side of P1. One end of the resistor R3 is connected to the collector of the transistor Tr2, and the other end is connected to the input plus side of the operational amplifier OP1. One end of the resistor R5 is connected to the emitter of the transistor Tr2, the other end is connected to the input plus side of the operational amplifier OP1, and similarly, one end of the resistor R7 is connected to the emitter of the transistor Tr2 and the other end is grounded. There is.
The negative input side of the operational amplifier OP1 is grounded through the parallel connection of the resistors R8 and R9, and the positive input side is grounded through the resistor R6. Also, the operational amplifier OP
The output side of 1 and the input negative side are connected via a resistor R10. On the other hand, the connection point of the resistors R2 and R4 described above is connected to one end of the switch SW via the diode D1. Resistor R7 in this current detection circuit 3
Is a resistor for detecting an on-current of the linear solenoid SL, and the resistor R2 is a resistor for detecting a surge current generated by a back electromotive force generated in the linear solenoid SL. In addition, resistors R3, R4, R5, R8
Is an input resistor of the operational amplifier OP1, and a resistor R6
R10 is a resistor for determining the amplification factor of the op amp OP1. The resistor R9 will be described later. Accordingly, the current detection circuit 3 can extract the current flowing through the linear solenoid SL, including the surge current, as a voltage Vi (t) signal at the output terminal of the operational amplifier OP1.
The diode D1 is for allowing a surge current generated when the transistor Tr2 is turned off to flow through the resistor R2.

The drive signal receiving circuit 4 includes a transistor Tr3 and a resistor R.
12 and R13. The base of the transistor Tr3 is connected to the control computer CP, and the emitter is grounded. The collector of the transistor Tr3 is connected to the power supply Vcc via the resistor R12 and is grounded via the resistor R13. As a result, the transistor Tr3 is turned on / off by receiving a pulse signal from the control computer CP at its base. At this time, the voltage VD (t) appearing at the collector of the transistor Tr3 is determined by the saturation voltage between the collector and the emitter when the transistor Tr3 is turned on, and the power supply Vcc by the resistors R12 and R13 when the transistor Tr3 is turned off. It depends on the partial pressure value of. Therefore, when the transistor Tr3 is driven by using the pulse signal having the predetermined duty ratio given from the control computer CP, the pulse output having the waveform inverted from the pulse signal is output to the collector as the voltage signal VD (t). As a result, the transistor Tr is changed according to the duty ratio of the pulse signal from the control computer CP.
Average value VD of collector voltage reflecting duty ratio of 3
ave, if the period of the pulse signal is T, expressed as _{^{VDave = ▲ ∫ T 0 ▼ VD}} (t) dt / T, linearly changes according to the duty ratio. This average value is used as the target value for the drive command of the linear solenoid SL. The maximum value of this target value is the transistor Tr3.
Is set to be larger than the voltage value Vi (t) corresponding to the maximum current value to be supplied to the linear solenoid SL, and the minimum value of the target value corresponds to the minimum current value to be supplied to the linear solenoid. It is set smaller than the voltage value Vi (t).

The deviation integration circuit 5 includes resistors R14 (R14 >> R12, R).
13) and a capacitor C1 connected in series, one end of the resistor R14 is connected to the collector of the transistor Tr3 of the drive signal receiving circuit 4, and the other end is connected to the operational amplifier OP1 of the current detection circuit 3 via the capacitor C1. Is connected to the output side of. As a result, the deviation integration circuit 5
Is the collector voltage VD (t) of the transistor Tr3 of the drive signal receiving circuit 4 and the operational amplifier OP1 of the current detecting circuit 3.
Will operate according to the difference in the output voltage Vi (t).

The switching control circuit 6 includes an operational amplifier O which is a comparator.
It is composed of P2 and a resistor R15, the positive input side of the operational amplifier OP2 is connected between the capacitor C1 and the operational amplifier OP1 of the current detection circuit, and the negative input side is between the capacitor C1 and the resistor R14. It is connected to the. The output side of the operational amplifier OP2 is connected to the base of the transistor Tr1 of the switching circuit 2 via the resistor R15 as described above. As a result, the switching control circuit 6 controls the operational amplifier OP2 according to the polarity of the charging voltage of the capacitor C1 of the deviation integration circuit 5.
Is turned on / off to turn on / off the transistor Tr1 of the switching circuit 2. The resistor R15 is a current matching resistor.

Next, the operation of the electromagnetic actuator drive device 1 of the present embodiment will be described centering on the deviation integration circuit 5.

FIG. 2 is a diagram in which the deviation integration circuit 5 is extracted and written. As shown in the figure, when the charge stored in the capacitor C1 is Q (t), VD (t) = R14 × dQ (t) / dt + Q (t) / C1 + Vi (t) ... (1) (However, The capacitance of the capacitor C1 is C1 and the resistance value of the resistor R14 is R14.) As a result, Q (t) = EXP (−t / A) × [1 / R14 × ▲ ∫ ^t ₀ ▼ [VD (t) -Vi (t)] * EXP (-t / A) dt] ... (2) (where A = C1 * R14). This capacitor C
The average value of the charge Q (t) accumulated in 1 becomes zero in the cycle T of the pulse signal. This is for the following reason. [Hereinafter, the above formula (2) representing the charge charge Q (t) is referred to as the charge charge formula (2). ] The collector voltage VD (t) (of the transistor Tr3 indicating the target current value that the output Vi (t) of the operational amplifier OP1 indicating the current value flowing in the linear solenoid SL (hereinafter simply referred to as the current value) flows in the linear solenoid SL. Less than,
It is simply called the target value. 2), the charging voltage polarity of the capacitor C1 becomes larger than the input plus side of the operational amplifier OP2 after a delay time due to the inductance load of the linear solenoid SL and the time constant of the deviation integrating circuit 5. As a result, the output of the operational amplifier OP2 becomes "L" level and the transistors Tr1 and T2
Each r2 is turned on, the current flowing through the linear solenoid SL increases, and the current value Vi (t) also increases. Current current value V
If i (t) increases and becomes larger than the target value VD (t), the charging voltage polarity of the capacitor C1 is determined by the operational amplifier OP2 after the delay time due to the inductance load of the linear solenoid SL and the time constant of the deviation integrating circuit 5. The input minus side of is smaller than the input plus side. As a result, the output of the operational amplifier OP2 becomes "H" level,
The transistors Tr1 and Tr2 are turned off, the current flowing through the linear solenoid decreases, and the current value Vi (t) also decreases. Therefore, the current value V is increased with a predetermined delay time.
Since the electromagnetic actuator drive device 1 operates so that i (t) follows the target value VD (t), in the steady state when the duty ratio of the target value VD (t) is constant, the capacitor C
The average value of the charge Q (t) accumulated in 1 becomes zero in the cycle T. Note that the delay time is the linear solenoid S due to the inductance load of the linear solenoid SL.
It depends on the response delay of L and the time constant of the deviation integration circuit 5. With this delay time delay, the target value VD (t) and the current value Vi (t) change at the same frequency. Therefore, the charge Q (t) of the capacitor C1 of the deviation integration circuit 5 changes in alternating current at the same frequency as the target value VD (t).

As described above, since the average value of the charge charge Q (t) accumulated in the capacitor C1 becomes zero in the period T of the pulse signal, the charge charge (2) equation can be replaced by the following equation.

_{^{0 = ▲ ∫ T 0 ▼ [}} VD (t) -Vi (t)] × EXP (-t / A) dt ... (3) [ hereinafter referred to as the (3) charges the formula (3) below. ] Here, the resistor R14 and the capacitor C of the deviation integration circuit 5
Time constant A = C1 × R14 determined by 1 is the target value VD
If it is much larger than the period T of the pulse signal of (t),
That is, if C1 × R14 >> T, EXP (−t /
A); (0 <t <T) can be approximately regarded as “1”. Accordingly, the charges (3) _{^{is, 0 = ▲ ∫ T 0 ▼}} [VD (t) -Vi (t)] dt , and the following equation is established.

▲ ∫ ^T ₀ ▼ VD (t) dt = ▲ ∫ ^T ₀ ▼ Vi (t) dt (4) This equation (4) is used for the target value VD (t) and the current value Vi (t).
Means that the average values of one cycle T are equal. Moreover, as described above, the target value VD
(T) and the current value Vi (T) operate at the same frequency. As a result, the charge Q (t) charged in the capacitor C1
Repeatedly charges and discharges at the same frequency as the target value VD (t) and inverts the charging voltage polarity. As a result, the operational amplifier OP2 controls the ON / OFF of the linear solenoid SL at the same frequency as the target value VD (t). It will happen. When the duty ratio of the target value VD (t) is changed, the average value of the current current Vi (t) in one cycle T is the target value VD (t).
Since the average value of (t) in one cycle T matches, the duty ratio of the target value VD (t) and the load current flowing through the linear solenoid SL have a linear relationship as shown in the graph of FIG. Becomes Therefore, the target value VD (t)
It is possible to control the load current flowing through the linear solenoid SL by controlling the duty ratio of the control computer CP.

In reality, there are cases where the time constant A = C1 × R14 cannot be increased beyond a certain value (in the present embodiment, A = 10 ×
T), in that case, EXP (−t / A) cannot be regarded as approximately “1” and is affected by EXP (−t / A), so that the voltage of the battery BT as a power source changes. However, it has been confirmed experimentally that it will be affected. However, since EXP (-t / A) 1 is established, if the influence of the power supply is corrected, it is hardly influenced. This correction is made by the resistor R9 of the current detection circuit 3.
(Hereinafter referred to as a correction resistor R9, R9 >> R8), and EXP (-) to the output Vi (t) of the op amp OP1.
It works to eliminate the influence of t / A). The graphs shown in FIGS. 4 (a) and 4 (b) show the experimental values. Fourth
The graph of FIG. 10A is a graph when the correction resistor R9 is not connected, and shows the relationship between the voltage of the battery BT as the power source and the load current flowing in the linear solenoid SL. As can be seen from this graph, even with the same duty ratio, it can be understood that the load current also changes with the change in the battery BT voltage and is affected by EXP (-t / A). On the other hand, due to the connection of the correction resistor R9, the fluctuation of the load current is suppressed within ± 3 mA between the battery voltage of 10-18 V, and the fluctuation of the battery voltage hardly affects the load current.
It is possible to obtain a linear relationship according to the duty ratio as shown in the graph.

The operation of the electric actuator drive device 1 has been described above centering on the operation of the deviation integration circuit 5, but the timing chart of FIG. 5 shows the above operation more specifically.

In the timing chart of FIG. 5, the pulse signal from the control computer CP is given with a duty ratio of 50%. Therefore, the target value VD (t) which is the collector voltage of the transistor Tr3 becomes the driving vibration of the linear solenoid SL having the duty ratio of 50% [FIG. 5 target value VD (t)]. On the other hand, the current current Vi (t), which is the output voltage of the operational amplifier OP1, is equal to the target value VD (t) and one cycle T.
The values are equal to each other as the average value of, and operate at the same frequency [Fig. 5 current current value Vi (t)]. Therefore,
The deviation integrator circuit 5 integrates the change in the collector voltage VD (t) of the transistor Tr3 and the current value Vi.
Since (t) changes in the cycle T, the charging voltage Vp of the capacitor C1 changes in the cycle T as shown by the charging voltage of the capacitor C1 in FIG. Charging voltage of capacitor C1], and accordingly, the output of the operational amplifier OP2 is turned on / off according to the change in polarity of the charging voltage of the capacitor C1 [output of operational amplifier OP2 in FIG. 5], transistor Tr2.
Is turned on / off to control the linear solenoid SL [collector voltage of transistor Tr2 in FIG. 5].

According to the electromagnetic actuator driving device 1 of this embodiment, the pulse signal from the control computer CP can be directly received by the electromagnetic actuator driving device 1 to drive the linear solenoid SL. Does not require an expensive D / A converter or the like for converting the signal into an analog signal, and only one signal line needs to be directly connected from the control computer CP. Moreover, it is possible to drive the linear solenoid SL with a very simple structure without using the sawtooth wave generation circuit used conventionally. As a result, the manufacturing process can be simplified, the number of parts can be reduced, and the cost can be reduced.

As described above, in the present invention, a simple integrator circuit is charged and discharged based on the pulse signal and the detected current, and the polarity of the capacitor of this integrator circuit is changed in the same cycle as the pulse signal, Utilizing this change in polarity, the energization of the electromagnetic actuator is interrupted, and the energization current is feedback-controlled to the target current indicated by the duty ratio of the pulse signal. Therefore, the electromagnetic actuator can be intermittently controlled by a simple integrating circuit, and heat generation can be suppressed. Moreover, the electromagnetic circuit can be connected and disconnected according to the deviation between the detected current and the target current by this integrating circuit, and the circuit configuration can be simplified. Further, since the target current value can be input by the duty ratio of the pulse signal, the current value of the electromagnetic actuator can be feedback-controlled by the pulse signal from the microcomputer. Further, since the time constant of the integrating circuit is set to be larger than the period of the pulse signal, the integrated voltage of the integrating circuit is not saturated, and accurate feedback control according to the duty ratio of the pulse signal can be performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an electromagnetic actuator driving device according to an embodiment of the present invention, FIG. 2 is a diagram showing a deviation integrating circuit in the electromagnetic actuator driving device, and FIG. 3 is a diagram showing the electromagnetic actuator driving device. FIG. 4 (a) is a graph showing the relationship between the duty ratio of the received pulse signal and the load current flowing in the linear solenoid SL, and FIG. 4 (a) is also linear with the battery BT voltage when the correction resistor R9 is not connected to the electromagnetic actuator drive device. Solenoid S
4 is a graph showing the relationship with the load current flowing through L, FIG. 4 (b) is a graph showing the relationship between the duty ratio of the pulse signal and the load current when the correction resistor R9 is also connected, and FIG. 6 is a timing chart showing the operation of each part of the actuator drive device. 1 ... Electromagnetic actuator drive device 2 ... Switching circuit 3 ... Current detection circuit 4 ... Drive signal receiving circuit 5 ... Deviation integration circuit 6 ... Switching control circuit BT ... Battery CP ... Control computer SL ... Linear solenoid SW …… Switch

Claims (3)

[Claims] 1. A switching element for connecting and disconnecting a current flowing through an electromagnetic actuator operated by electromagnetic force, a current detecting means for detecting a current flowing through the electromagnetic actuator, and a target value of a current flowing through the electromagnetic actuator. A drive signal receiving means for externally receiving a pulse signal having a duty ratio for instructing driving of the electromagnetic actuator, a resistor and a capacitor, and the current detected by the current detecting means and the drive signal. Charge and discharge based on the pulse signal received by the receiving means, and a deviation integration circuit whose time constant is larger than the cycle of the pulse signal, and the polarity of the charging voltage of the capacitor that changes at the same cycle as the pulse signal. Turn on the switching element accordingly.
An electromagnetic actuator driving device, comprising: a switching element control unit that controls OFF. 2. The electromagnetic element according to claim 1, wherein the switching element control means includes an operational amplifier circuit in which the capacitor is connected between a positive side input terminal and a negative side input terminal. Actuator drive. 3. The current detecting means detects a current of the electromagnetic actuator flowing when the switching element is on, and a surge current of the electromagnetic actuator flowing when the switching element is off. The electromagnetic actuator drive device according to claim 1, further comprising a second detection unit.