JPH08270485A - Idle speed control device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the resolution of idle speed control, and to guarantee idle speed control as soon as a disconnection occurs in the idle valve drive solenoid (fail safe). [Structure] 2 air flow valve drive solenoids for idle
It is divided into two coils 12A and 12B, and these coils are connected in parallel. The controller 3 uses the switching elements 4A and 4B to switch the coil 12 during the first idle.
Both A and 12B are selected, and the energization amount of these coils is controlled according to the required fast idle air flow rate, and only one of the coils 12A and 12B is selected during normal idle, and one of them is selected. The coil energization amount is controlled according to the required idle air flow rate. If one of the coils 12A and 12B is broken, the coil that is not broken is selected via the switch element and the duty is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling an idle speed of an automobile engine, and more particularly to a solenoid energization control technique for a valve drive actuator in idle speed control.

[0002]

2. Description of the Related Art Conventionally, upstream and downstream of a throttle valve in an intake system of an automobile engine are bypassed, an idle metering valve is arranged in this bypass passage, and the opening of the metering valve is controlled according to the engine water temperature. There is known an electronic control unit that controls the idle air flow rate and thus the engine speed (idle speed). An idle speed control device, for example, as disclosed in Japanese Patent Laid-Open No. 6-235372, has a solenoid inside a fixed core and a movable plunger with a valve element (measuring valve), and the electromagnetic force generated by the solenoid The amount of movement of the plunger is adjusted by the balance of the force of the return spring, and the opening of the metering valve and thus the idle air flow rate are controlled to control the idle speed. The amount of movement of the plunger (metering valve opening) is usually performed by duty-controlling the current flowing through the solenoid. The solenoid of this kind of idle speed control device is generally composed of a single coil.

In fields other than the idle speed control device, the return spring force of the plunger is set to two or more stages, as in the multi-stage electromagnetic control valve disclosed in Japanese Patent Laid-Open No. 59-50284. Correspondingly, the plunger driving coil is divided into a plurality of coils in a parallel mode, and electric currents of different magnitudes are made to flow through the coils in a stepwise manner so that the electromagnetic force generated is at two or more levels, and at two or more positions on the valve body. There is a method of switching communication between a plurality of ports by performing stepwise control.

[0004]

[Problems to be Solved by the Invention]

(1) In the conventional idle speed control device, the solenoid is formed of a single coil, but in this method, the resolution of idle speed control (air flow rate to solenoid current, so-called solenoid current-air flow rate characteristic) Of the idle air flow rate is desired due to requirements such as low fuel consumption, quietness, and low pollution, especially during normal idle operation after warming up. When performing feedback control of the idle speed control below, it is necessary to increase the resolution of the idle speed control and improve its control accuracy.

(2) In addition, a fail-safe measure is urgently considered in consideration of self-propelled running even when the switching element of the controller for controlling the solenoid is broken or the coil is broken.

Conventionally, regarding these requirements, no consideration has been given to solving the problems (1) and (2) by improving the solenoid and the controller system.

The present invention has been made in view of the above points, and has a first aspect.
An object of the present invention is to improve the idle speed control accuracy by increasing the control resolution, particularly in the low flow rate region, by a simple method in the above-mentioned problem (1).

An object of the second invention is to satisfy the fail-safe which is the problem of (2) in addition to the problem of (1) above.

[0009]

The first invention is basically constructed as follows.

That is, in an idle speed control device for controlling the amount of electricity supplied to the metering valve driving solenoid to control the idle air flow rate of the engine and thus the idle speed, the solenoid is divided into two coils, a first coil and a second coil. These coils are connected in parallel, and both the first and second coils are selected as the solenoids to be used during the fast idle, and the energization amount of these coils is set to the required fast idle air. Control according to the flow rate, select only one of the first and second coils as the solenoid to be used during normal idle, and set the energization amount of the one coil according to the required idle air flow rate. It is characterized by comprising a control unit for controlling by.

According to a second aspect of the present invention, in addition to the constituent features of the first aspect of the invention, the control unit monitors whether or not each system of the first and second coils is broken, and When a disconnection occurs in one wiring system, the configuration has a fail-safe function that controls the energization of only the other coil in which the disconnection has not occurred to perform idle speed control.

[0012]

Operation of the first invention: Fig. 4 shows an example of solenoid current (valve drive current; duty) -air flow rate characteristics of the idle speed control device according to the present invention, and Fig. 5 shows conventional automotive engine specifications. An example of the solenoid current-air flow rate characteristic of the idle speed control device of FIG. In the present invention, the solenoid of the idle speed control device, which is conventionally formed of a single coil, is divided into two coils, a first coil and a second coil, which are connected in parallel. A in the solid line in FIG. , A diagram showing solenoid current-air flow rate characteristics when both the second coil and the second coil are energized, the solid line B indicates the solenoid current when either one of the first and second coils forming the solenoid is selected. -It is an air flow rate characteristic. When the number of turns of the first and second coils is the same, when a current is selectively applied to either one of the coils, the maximum duty (conduction rate 100%) is obtained as indicated by the solid line B. It is assumed that the air flow rate Q corresponding to the opening of the metering valve is 500 (l / min). Under the above conditions, when both the first and second coils are energized, the number of coil turns is doubled and the electromagnetic force (valve driving force) is doubled in calculation, so the solid line A is As shown in the figure, the air flow rate Q when a current of maximum duty (commutation rate 100%) is applied to both coils is 10 when the metering valve is fully opened.
It becomes possible to flow 00 (l / min) (In other words, when only one of the first and second coils is flowed, the valve opening at 100% duty is half of the full opening. ). Further, the slope of the solenoid current-air flow rate characteristic of the solid line B is approximately 1/2 compared to the solenoid current-air flow rate characteristic of the solid line A.

Generally, fast idle operation (see FIG.
In the example of FIG. 5, 1500 to 2000 rpm),
The idle air flow rate is relatively high, for example 800
~ 900 (l / min) is required. In the present invention, in this case, the control unit controls the current to flow through both the first and second coils, and the energization amount of the first and second coils is, for example, in the range of duty 65 to 75%. The electric current of.

Next, a normal idle operation range (for example, 800
˜1000 rpm), an idle air flow rate of 70 to 100 (l / min) is generally required. In the present invention, when such idling speed control in the low flow rate range is required, the control unit
One of the second coils is selected and controlled so that a current flows. In this case, the number of coil turns used is reduced, so the duty is larger than in the conventional example of FIG. For example, the duty is 35 to 45% (current value 0.35 to 0.45 amperes). In the conventional case, since a single coil is always used (the number of turns corresponds to the total sum of the first and second coils of the present application), the exciting force per unit duty (%) and thus the idle opening is large, so normal idle rotation is performed. The required solenoid duty is, for example, 25-30% (current value 0.25-0.3 amperes)
About.

From the above numerical values, the normal idle rotation range of the present invention in FIG. 4 (for example, 800 to 1000 rpm)
The required air flow rate range is 100-70.
= 30 (l / min), the required duty range is 45-35 = 10%.

[0016]

## EQU1 ## 30 (l / min) /10%=3.0 (l / min) /% That is, the rate of change of the flow rate per 1% duty is 3
(L / min).

Similarly, when the resolution in the conventional normal idle rotation range (for example, 800 to 1000 rpm) in FIG. 5 is obtained,

[0018]

## EQU00002 ## 30 (l / min) /5%=6.0 (l / min) /% That is, the rate of change of the flow rate per 1% duty is 6
(L / min).

From the above, the resolution of the solenoid current-air flow rate characteristic is particularly doubled in the low flow rate range (normal idle rotation speed range) of the idle air flow rate as compared with the conventional one, so that the idle rotation requiring feedback control is required. The air flow rate control of the number control can be finely performed, and the accuracy of the idle speed control can be improved.

Operation of the second invention: When a wire break occurs in one of the first and second coils, the control unit detects this and controls the energization of only the other coil in which no wire break occurs. That is, in the example of FIG. 4, the idle rotation control is urgently performed based on the air flow rate-current value characteristic of the solid line B in the fast idle operation as well as in the normal idle operation. In this case, normal idle speed control is guaranteed in normal low flow rate idle operation. In fast idle operation, the maximum duty current is applied to the coil on only one side (the coil that has not been broken) to guarantee a flow rate of up to half the normal maximum flow rate for emergency self-driving. It is possible to realize fail-safe with.

[0021]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a control system of an idle speed control device according to a first embodiment of the present invention, and FIG. 2A is a meter with a drive actuator for idle speed control used in this embodiment. Sectional drawing of a valve mechanism, (b) is explanatory drawing which shows typically the winding mode of the solenoid of the drive actuator, FIG. 3 is the flowchart of the idle speed control in this Example, FIG. 4 is the metering valve in this Example. It is a diagram which shows the solenoid current for drive-air flow rate characteristics.

First, the configuration of FIG. 2 will be described.

The metering valve mechanism with an actuator (idle air flow rate control valve) shown in FIG.
0 and the metering valve mechanism 20.

In the actuator section 10, a valve driving solenoid 12 is housed in a cylindrical case 11 whose one end is open. The solenoid 12 is divided into two coils, a first coil 12A and a second coil 12B. In this embodiment, as shown in FIG.
Through the power supply terminal A and the second power supply terminal B of the coil 12
A and 12B are connected in parallel, and these coils are separately formed and juxtaposed in the bobbin 13 in the axial direction,
The entire solenoid 12 is insulation-coated with the molding resin 14.

A fixed core 15 is provided inside the solenoid 12.
And a plunger (movable core) 16 are arranged to face each other in the axial direction. The plunger 16 energizes one or both of the coils 12A, 12B to generate springs 17, 18
Is magnetically attracted to the fixed core 15 side up to a position balanced with. A pair of metering valves 21, 22 are provided at one end of the plunger 16.
The rod 19 with which the metering valve 2 is connected is made movable together with the plungers 16, and the metering valves 2 and 22 are moved by a stroke proportional to the energization amount of the solenoid 12.
The opening degree of the valves 1 and 22 (the amount of the gap between the metering valves 21 and 22 and the corresponding seat portions 26 and 27 of the flow path body 23) and the air flow rate for idle are controlled. The spring 17 is interposed between one end of the plunger 16 and one end of the case 11 to urge the spring force in the direction in which the metering valves 21, 22 open, and the spring 18
Intervenes between an adjuster 24 attached to one end of a flow path body 23 of the metering mechanism section 20 described later and the metering valve 22 to urge the metering valves 21 and 22 in a closing direction. The spring load of the spring 18 is larger than that of the spring 17.

30 is a power supply terminal for external connection [(b) of FIG. 2]
[Corresponding to E terminal, A terminal, and B terminal] of FIG.

The measuring mechanism section 20 has a flow path body 23 attached to a throttle chamber (not shown) of an engine intake system.
The flow path body 23 communicates with a bypass element 25A communicating with the upstream side of the throttle valve provided in the throttle chamber, a bypass element 25B communicating with this bypass element 25A through a communication passage not shown, and a downstream side of the throttle valve. The bypass air flow path for idle composed of the bypass element 25C is provided, and the bypass element 25 is provided when the metering valves 21 and 22 are opened.
A and 25B communicate with the bypass element 25C, and idle air flows to the bypass as shown by the arrow.

Reference numeral 31 is an O-ring for maintaining the sealing property between the case 11 and the molding resin 14, 32 is an O-ring for maintaining the sealing property of the connecting portion between the actuator portion 10 and the measuring mechanism portion 20, and 33 is an It is an O-ring that maintains the sealing performance between the adjuster 24 and the flow path body 23. The adjuster 24 is for adjusting the spring load of the return spring 18.

Next, the control system of the idle speed control device of the present embodiment will be described with reference to FIG.

In FIG. 1, 1 is an engine, and 2 is an idle air flow rate control valve (idle speed control valve; ISC valve), which has the configuration of FIG.

3 is an engine control unit,
It is shown here in connection with the data input elements required for idle speed control. The function of the control unit 3 will be described later. Reference numerals 4A and 4B denote power transistors serving as switching elements for coil energization. The bases of the switching elements 4A and 4B are connected to the output terminals of the control unit 3, respectively, and the collector of the switching element 4A is the first coil 12A of the solenoid 12.
Of the switching element 4B is connected to the terminal B of the second coil 12B, and the emitters of the switching elements 4A and 4B are grounded. Between the collector and emitter of the switching elements 4A and 4B,
A Zener diode 5 for preventing overvoltage protection is connected to each.

As described above, the first and second parts are divided into two parts.
The second coils 12A and 12B are connected in parallel, and the respective surge absorbing diodes 6 are connected in parallel to the respective coils 12A and 12B. The surge absorbing diode 6 is
Energization of the coils 12A and 12B is controlled by switching elements 4A
When turned off at 4B, the electric energy stored in the coils 12A and 12B is absorbed. Coils 12A, 12B
Common terminal E of is connected to the (+) side of the power supply (battery) V _B. A coil current detector (resistor) 7A serving as a disconnection / short-circuit detector is connected between the coil 12A and the collector of the switching element 4A, and a coil current that is the same as the coil current between the coil 12B and the collector of the switching element 4B is used. The detector 7B is connected. The detectors 7A and 7B convert the current flowing through the coil into a resistance value and detect the presence or absence of disconnection or short circuit. The output signals of the current detectors 7A and 7B are input to the disconnection / short circuit determination device 40 via the amplifier 8 and the A / D converter 9, respectively.

The control unit 3 inputs detection signals of the engine water temperature sensor 41, the idle switch 42, the engine speed sensor 43, the engine load (for example, a car air conditioner) 44, etc., and is required for the set idle speed during idle operation. The air flow rate and the fuel injection pulse width are calculated, and the coils 12A and 12B are switched through the switching elements 4A and 4B by the duty signal corresponding to the air flow rate.
Of the metering valves 21 and 22 provided in the bypass passage for idling (shown by reference numerals 25A, 25B and 25C in FIG. 2) for feedback control of the idling speed. .

When performing the idle speed control, the control unit 3 selects both the first and second coils 12A and 12B as the solenoids to be used through the switching elements 4A and 4B at the time of the first idle, The value of the current flowing through these coils 12A and 12B is the required fast idle air flow rate in accordance with the characteristics of the solid line A in FIG. 4 (solenoid drive current-air flow rate characteristics when both coils 12A and 12B are energized). [Generally 800-900
(About 1 / min)], for example, 0.65 to 0.7
Control to about 5 amps (duty 65-75%). The duty values (energization amounts) of the coils 12A and 12B are equal.

At the time of normal idling, only one of the first and second coils 12A and 12B (here, for example, 12A) is selected as the solenoid to be used via the switching element 4A, and one of them is selected. Coil 1
2A, the value of the current flowing through
2A, 12B shows the solenoid current-air flow rate characteristics when energizing either coil)
Required idle air flow rate [typically 70-100 (l
/ Min)], for example, control is performed in the range of 0.35 to 0.45 amperes (duty 35 to 45%).
When shifting from the fast idle operation to the normal idle operation, the control unit 3 gradually reduces the duty of the current flowing through both the first and second coils 12A and 12B, and then is used for the normal idle operation. One coil 12A is selected and the current flowing through the selected coil 12A is duty controlled. In this way, the rapid change of the idle air flow rate is eliminated and the normal idle operation is smoothly shifted from the first idle.

When a relatively large engine load such as a car air conditioner is applied during idle operation,
500 as the idle air flow rate during normal idle operation
(L / min) is required. In this case, when the coil 12A (or the coil 12B) is selectively used as in the above,
If a current with a duty of 100% is applied to A, as is clear from the characteristics of the solid line B in FIG. 4, good idle speed control can be secured. When a relatively large engine load such as a car air conditioner during fast idle operation is applied, the coils 12A and 12B are used to perform duty control so as to secure an air flow rate corresponding to the engine load correction.

Next, when the switching elements 4A and 4B are out of order due to a failure or when a part of the solenoid 12 is broken, the control unit 3 causes the coil current detectors 7A and 7B and its determiner. Based on the input data obtained through 40, a normal coil is selected from the coils 12A and 12B through the switching element 4A or 4B, and the solenoid current flowing through the selected coil is used for normal idle operation and fast idle operation. The duty control is performed according to. In this case, normal idle speed control is guaranteed in normal low flow rate idle operation. In the fast idle operation, the maximum duty current is applied to the coil on one side that is not broken,
It is possible to guarantee an idle air flow rate up to half of the maximum flow rate in a normal case and realize a fail-safe with emergency self-driving.

When a short circuit failure occurs in either one of the switching elements 4A and 4B, the coil on the other switching element side, in which no failure has occurred, is shut off to perform idle operation. In this case, the current is allowed to flow to the coil on the short-circuited side, but the coil on one side 12A or 1
Since only 2B is used, the idle air flow rate can be limited to about half the maximum flow rate, so that fail-safe can be realized.

FIG. 3 shows the above in the engine operating state.
The content of the idle control operation of is shown by a flowchart.

According to the present embodiment, in the normal idle operation range (low idle flow rate range), as described above, either one of the coils 12A and 12B is selected and the current flows. Because it is controlled to flow,
When the normal idle operation is performed, the number of coil turns used is reduced, so that the conventional solenoid current of FIG.
The duty is larger than the air flow rate characteristic, and the duty range is 35 to 45%. In the conventional case, as described in the section of the operation of the invention, the duty of the solenoid normally required for idle rotation is 25 to 30%.
(Current value is 0.25 to 0.3 amperes).

From the above numerical values, the resolution in the normal idle rotation range (for example, 800 to 1000 rpm) in FIG. 4 can be obtained from Equation 1 described in the section of the operation of the invention.
0 (l / min) / (duty%), and similarly, when the resolution of the conventional idle rotation range (for example, 800 to 1000 rpm) of the conventional one-coil method in FIG. 1 / min) / (duty%), and the resolution of the air flow rate-current value characteristic of the idle rotation control particularly in the low flow rate range (normal idle speed range) is twice that of the conventional one (in other words, the air flow rate). -Since the slope of the current value characteristic line is 1/2 compared to the conventional one, it becomes possible to finely control the idle air flow rate of the idle speed control that requires feedback control, and improve the accuracy of the idle speed control. Can be increased.

Further, according to the present embodiment, even if a part of the solenoid is broken or short-circuited, the above-described operation can realize fail-safe idle operation.

FIG. 6 shows a second embodiment of the present invention.
The control system is the same as that of FIG. 1 used in the first embodiment. The difference between this embodiment and the first embodiment is that the coil 12
That is, A and 12B are wound in layers. According to this embodiment, in addition to the effects of the first embodiment, the coils 12A and 12B are
The bobbin has the advantage that it can be used with the same one as the conventional single coil system.

[0045]

As described above, according to the first aspect of the present invention, in idle speed control, the control resolution,
In particular, it is possible to improve the resolution of the idle low flow rate region and improve the idle speed control accuracy.

Further, according to the second invention, in addition to the effect of the first invention, even if a disconnection occurs in the valve driving solenoid for idle operation and its system, a fail-safe for ensuring emergency idle operation. Can be realized.
In particular, in the present invention, there is no need to use an idle air flow rate control valve having the same function in combination to prepare for a failure, and the above fail safe can be achieved with one idle air flow rate control valve, and the cost is economical.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a control system of an idle speed control device according to a first embodiment of the present invention.

FIG. 2A is a sectional view of a metering valve mechanism with a drive actuator for idle speed control used in the above embodiment,
FIG. 3B is an explanatory view schematically showing a winding mode of a solenoid of the drive actuator.

FIG. 3 is a flowchart of idle speed control in the above embodiment.

FIG. 4 is a characteristic diagram of a solenoid current for driving a metering valve-air flow rate in the above embodiment.

FIG. 5 is a characteristic diagram of a solenoid current for driving a metering valve of a conventional idle speed control device-air flow rate.

FIG. 6A is a sectional view of a metering valve mechanism with a drive actuator for idle speed control used in a second embodiment of the present invention, and FIG. 6B is a schematic view of a winding mode of a solenoid of the drive actuator. FIG.

[Explanation of symbols]

1 ... Engine, 2 ... Idle air flow control valve, 3 ... Control unit, 4A, 4B ... Switching element, 7
A, 7B ... Coil current detector (disconnection / short-circuit detector), 1
2 (12A, 12B) ... Solenoid for driving metering valve (first and second coils), 40 ... Disconnection / short circuit judging device.

Claims (6)

[Claims] 1. An idle speed control device for controlling an energization amount of a metering valve driving solenoid to control an idle air flow rate of an engine and thus an idle speed, wherein the solenoid is divided into two coils, a first coil and a second coil. These coils are connected in parallel, and both the first and second coils are selected as the solenoids to be used in the fast idle, and the energization amount of these coils is set to the required fast idle air. Control according to the flow rate, select only one of the first and second coils as the solenoid to be used during normal idle, and set the energization amount of the one coil according to the required idle air flow rate. An idle speed control device, comprising a control unit for controlling the idle speed. 2. The idle speed according to claim 1, wherein the first and second coils are connected in parallel, and each coil is provided with a switching element for controlling coil energization in response to a command signal from the control unit. Control device. 3. The control unit monitors the presence or absence of disconnection of each system of the first and second coils, and when a disconnection occurs in one of the systems, only the other coil in which no disconnection occurs The idle speed control device according to claim 1 or 2, further comprising a fail-safe function for controlling the energization of the engine to control the idle speed. 4. The control unit monitors whether or not there is a short circuit in a switching element of each system of the first and second coils, and when a short circuit failure occurs in one of the switching elements, the failure has occurred. The idle speed control device according to any one of claims 1 to 3, further comprising a fail-safe function of shutting off the other switching element side coil to perform an idle operation. 5. The control unit duty-controls the currents flowing through the first and second coils, and, when shifting from a fast idle operation to a normal idle operation, controls both the first and second coils. After gradually reducing the duty of the current flowing through the coil, one of the coils used for normal idle operation is selected, and the current flowing through the selected coil is set to be duty controlled. Any one of claims 1 to 5
The idle speed control device according to the paragraph. 6. The idle rotation according to any one of claims 1 to 5, wherein the first coil and the second coil are separately formed and arranged side by side in the axial direction, or are wound in layers. Number control device.