JP2000145597A - Drive controller for solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure that even low-resolution CPUs offer flow rate control of fluid of an equivalent precision as by high-resolution CPUs. SOLUTION: For duty-controlling a solenoid valve 13 interposed in a fluid passage, a control means 1 uses a target flow rate setting means 2 to set a target flow rate of fluid flowing through the fluid passage and next a drive duty setting means 3 to update the drive duty of the solenoid valve 13 in a preset control cycle depending on the target flow rate. The drive duty setting aims the mean value of all drive duty values set in continuous control cycles at the target flow rate. According to the drive duty the drive duty setting means 3 sets, a control signal output means 5 outputs control signals to the solenoid valve 13 to duty-control it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve drive control device interposed in a fluid flow passage and driven to open and close by duty control, and more particularly to a solenoid valve suitable for use in a solenoid valve for adjusting intake air of an internal combustion engine. The present invention relates to a valve drive control device.

[0002]

2. Description of the Related Art Conventionally, a solenoid valve has been used as a means for controlling the flow rate of a fluid, and flow rate control by duty control of the solenoid valve has been widely performed. In this duty control, a drive duty is determined according to a target fluid flow rate (flow rate per unit time), and a target fluid flow rate is obtained by opening and closing a solenoid valve according to the determined drive duty. Things.

By the way, in a solenoid valve,
Normal PWM method [that is, pulse width modulation (pulse width mo)
dulation) method], the drive time T with respect to the control cycle T ₂ (for example, 5 msec)
Control is performed so that the ratio of ₁ becomes equal to the drive duty.
Actually supplied fluid flow rate error with respect to the fluid flow rate to the target in this case, setting accuracy of the drive duty, i.e., depends on whether it how finely set the drive time T ₁ to the control period T _2, the end And the resolution of the CPU that drives and controls the solenoid valve. For example, 8 if the bit of the CPU, for its resolution is 1/256, drive time T ₁ whereas the settings in T _2/256 seconds, if 10-bit CPU, the resolution since it is 1/1024, drive time T ₁ is T _2/10
It can be set in units of 24 seconds.

[0004]

The above-mentioned solenoid valve as a means for controlling the flow rate of the fluid is also used in an engine of an automobile. For example, in an engine that performs super lean burn operation by stratified combustion while significantly increasing the air-fuel ratio (for example, an in-cylinder injection engine that injects fuel in a cylinder), as shown in FIG. Engine 1 to supply a large amount of air
In the intake system to 0, a bypass passage 12 is provided separately from a normal intake passage 11 provided with a throttle valve 14. As a flow control means for the bypass passage 12, a solenoid valve [hereinafter referred to as an air bypass valve (ABV)] is used. 13 are provided. In FIG. 4, 21 is an intake path, 22 is an exhaust path, and 23 is an exhaust gas purifying catalyst.

[0005] An ECU (electronic control unit) 20
Then, the operation mode is set based on the operation state of the engine 10, for example, the engine speed detected by the crank angle sensor 15, the opening of the throttle valve 14 detected by the throttle opening sensor 16, and the like. However, if the operation is ultra lean burn, the target air-fuel ratio is set to a large value according to the operation state, the target fuel injection amount and the like are set, and the target air-fuel ratio is set based on the air flow rate detected by the air flow sensor 17. Duty control of the air bypass valve 13 is performed to adjust the opening degree of the bypass passage 12 so that the intake air amount can achieve the fuel ratio.

In this example, the bypass passage 12 is used as a supply passage of rotation speed control (ISC) air during idling operation in addition to the supply of lean operation air.
That is, when idle operation is detected by the idling switch 18, the ABV 13 is driven to supply ISC air, and control is performed so that the engine speed is maintained at a predetermined idle speed.

However, the bypass passage 12 is of a large diameter in order to supply a large amount of air at the time of lean operation, and when a small amount of the ISC air is supplied in an appropriate amount, an error becomes large. Cheap. If the supply error of the ISC air is large, the engine speed will deviate from the target idle speed. Therefore,
In this case, the setting accuracy of the drive duty of the ABV 13, that is, the resolution of the CPU that drives the ABV 13 is preferably as high as possible.

However, the CPU provided in the existing solenoid valve drive control device has a low resolution and a large error in the supply of ISC air, so that the engine speed is sufficiently brought close to the vicinity of the idle speed. Is difficult to keep. Of course, the CPU provided in the solenoid valve drive control device may have a sufficiently high resolution. However, since the use of a CPU having a high resolution leads to an increase in cost, it is provided in the existing solenoid valve drive control device. It is desired that accurate flow control can be performed even by a CPU having a low resolution.

The present invention has been made in view of such a problem, and a high-resolution CP can be realized by a low-resolution CPU.
An object of the present invention is to provide a solenoid valve drive control device capable of controlling the flow rate of a fluid with the same accuracy as U.

[0010]

In order to achieve the above object, in a solenoid valve drive control device according to the present invention, in a duty control of a solenoid valve interposed in a fluid flow path by a control means, first, a target flow rate is set. The means sets a target flow rate of the fluid flowing in the fluid flow path, and the drive duty setting means sets and updates the drive duty of the solenoid valve at a predetermined control cycle so as to correspond to the target flow rate. However, the setting of the drive duty at this time is such that the average value of the plurality of drive duties set respectively in the plurality of continuous control cycles corresponds to the target flow rate. The control signal output means outputs a control signal for duty control of the solenoid valve according to the set drive duty.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are functional block diagrams showing a solenoid valve drive control device according to an embodiment of the present invention. The solenoid valve drive control device according to the embodiment performs an engine (see FIG. 4) Air bypass valve (ABV) 13
The description will be made assuming that the present invention is applied to the driving of.

First, the configuration of the present solenoid valve drive control device will be described. As shown in FIG. 1, the present solenoid valve drive control device transmits an idle signal indicating that the engine is idling to an idle switch 18 (see FIG. 1). Control means (ECU) 1 for driving the ABV 13 to open and close by duty control when input from the ECU 4
Is provided. The control means 1 includes a target idle speed setting means 2 for setting a target idle speed, a target duty setting means (target flow rate setting means) 3, a drive duty setting means 4, and an ABV drive driver (control signal output means). And 5).

The target idle speed setting means 2 determines an idle signal from the idle switch 18 (see FIG. 4) and an engine load state (for example, a coolant temperature, an operation state of an air conditioner, and a selected position state of an automatic transmission). When an idle signal is input and received, a target idle speed corresponding to the engine load state is set. Target duty setting means 3
Calculates the target flow rate of the idle speed control (ISC) air so that the engine speed approaches the target idle speed set by the target idle speed setting means 2, and sets the ABV 13 in accordance with the calculated target flow rate. It has a function of setting the duty to be driven (target duty). That is, the target duty setting means 3 determines from the engine speed information based on the information from the crank angle sensor 15 that if the actual engine speed is lower than the target idle speed, the target value of the air amount flowing through the ABV 13 (the target flow rate) ) Is increased by a predetermined amount with respect to the current target flow rate, and if the actual engine speed is higher than the target idle speed, the target flow rate is reduced by a predetermined amount with respect to the current target flow rate, thereby periodically (for example, 1). The target flow rate is updated and set every second), and the target duty of the ABV 13 is updated and set according to the updated target flow rate.

The target duty is 10-bit data, that is, 1/2 ¹⁰ [= 100/1024.
(%)]. The drive duty setting means 4 converts the target duty set by the target duty setting means 3 into an ABV drive driver 5 described later.
Is a means for resetting the duty to a value corresponding to the resolution.
For example, if the resolution of the ABV drive driver 5 is 8 bits, it is necessary to reset the target duty set as 10-bit data to 8-bit data.

Therefore, the drive duty setting means 4
First, of the 10-bit target duty set by the target duty setting means 3, the lower 2 bits are discarded and the remaining upper 8 bits are set as the drive duty. Then, by pattern-controlling the least significant bit of the drive duty, when the drive duty is averaged over time, the average value is equal to the target duty. This pattern control is performed by pattern control means 6 provided as a functional element.

The pattern control means 6 stores the lower 2 bits of the target duty which is cut off when setting the drive duty.
A control pattern corresponding to the bit arrangement is stored.
In this control pattern, for example, as shown in FIG. 2, four cycles of the timer in the control means 1 are set as one cycle, and "1" (voltage Hi),
“0” (voltage Low) is set, and four patterns are prepared for each of the lower 2 bits of the target duty.

The setting of the control pattern for each array will be described. First, the control pattern when the array of the lower two bits is "00" is set to "0000" every cycle. Similarly, the array of the lower 2 bits is “0”.
If it is "1", it is set to "0001", if the array of lower 2 bits is "10", it is set to "0101", and if the array of lower 2 bits is "11", it is set to "0111". Here, one cycle of the timer is, for example, about 20
msec, and one cycle of pattern control is about 80 msec.

The pattern control means 6 selects a pattern in accordance with the arrangement of the lower 2 bits of the target duty from the stored four types of control patterns, and according to the pattern,
The least significant bit of the drive duty is pattern-controlled. That is, in a certain control routine, if the control pattern is “0”, “0” is added to the least significant bit of the drive duty, and if the control pattern is “1”, “0” is added to the least significant bit of the drive duty. "1" is added. If the target duty changes during one cycle, the cycle is stopped,
A control pattern corresponding to the arrangement of the lower 2 bits of the changed target duty is selected, and the cycle is started again from the beginning.

The ABV drive driver 5 is a means for outputting a control signal for driving the ABV 13 in accordance with the drive duty of 8-bit data set by the drive duty setting means 4. The control signal output from the ABV drive driver 5 turns on and off a solenoid (not shown) provided in the ABV 13, thereby controlling the ABV drive.
The opening and closing drive is performed by the duty control of No. 13.

Since the solenoid valve drive control device according to one embodiment of the present invention is configured as described above,
Lean burn engine air bypass valve (ABV)
The drive control of 13 is performed as follows. First,
When the control means 1 receives an idle signal from the idle switch 18 (see FIG. 4), the target idle speed setting means 2 sets engine load information (water temperature information, air conditioner operating state information, selected position state of the automatic transmission, etc.). Set the target idle speed according to ().

In the target duty setting means 3,
Based on the engine speed information, A is set based on the engine speed information so that the engine speed approaches the target idle speed set by the target idle speed setting means 2 based on the engine speed information.
A target value (target flow rate) of the amount of air flowing through the BV 13 is set, and a target duty of the ABV 13 is set according to the target flow rate. That is, if the actual engine speed is lower than the target idle speed, the target flow rate of the ABV 13 is increased by a predetermined amount with respect to the current target flow rate, and if the actual engine speed is higher than the target idle speed, the target flow rate is increased. The target flow is updated and set periodically by decreasing the target flow by a predetermined amount, and the target duty of the ABV 13 is updated and set according to the updated and set target flow.

At this time, the target duty setting means 3 sets the target duty, that is, the target drive duty according to the target flow rate, as 10-bit data. When the target duty is set, the drive duty setting means 4 sets the 10-bit target duty to AB
The data is reset to 8-bit data according to the resolution of the V drive driver 5.

First, drive duty setting means 4
The lower 2 bits of the target duty of the bits are discarded, and the remaining upper 8 bits are set as the drive duty. At the same time, a control pattern corresponding to the arrangement of the lower 2 bits cut off by the pattern control means 6 is selected, and pattern control of the least significant bit of the drive duty is performed according to the selected pattern.

If the target duty set by the target duty setting means 3 is, for example, "1001110101" (= 61.426%) as 10-bit data, the driving duty setting means 4 first sets the target duty. Drive duty is set to “10011101” (= 61.328%) based on the upper 8 bits of. At the same time, the control unit 6 selects the control pattern "0001" according to the lower two bits "01" of the target duty.

When four cycles of the timer are one cycle,
Since the control pattern is “0” in the first to third cycles,
The least significant bit is not incremented, and the drive duty remains “10011101” (= 61.328%). On the other hand, in the fourth cycle, since the control pattern is “1”, the least significant bit is incremented by 1 and the drive duty is “10011110” (= 61.718%).
Becomes In other words, the drive duty is 1 for every 4 cycles of the timer.
It changes from 61.328% to 61.718% at the rate of times.

When the target duty is increased by the minimum unit as compared with the above example, that is, the least significant bit is incremented by 1 and "1001110110" (= 61.52)
3%), the drive duty setting means 4
The drive duty set based on the upper 8 bits of the target duty is “10011101” (= 61.328).
%), And at the same time, the control pattern selected by the pattern control means 6 according to the lower two bits “10” of the target duty is “0101”.

In this case, since the control pattern is "0" in the first and third cycles, the least significant bit is not incremented, and the drive duty is "10011101" (=
Since the control pattern is “1” in the second and fourth cycles, the least significant bit is incremented by 1 and the drive duty is “10011”.
110 "(= 61.718%). That is, the drive duty repeatedly changes between 61.328% and 61.718% for each cycle of the main routine.

The ABV driving driver 5 drives the ABV 13 with the driving duty set in this way.
Outputs a control signal corresponding to the drive duty to the ABV 13, and periodically turns on and off a solenoid (not shown) provided in the ABV 13. At this time, since the solenoid has a sufficient responsiveness, it can sufficiently follow a duty change of about one cycle of the timer (for example, about 20 msec).

As a result, the duty of the ABV 13 changes in accordance with the set driving duty. In the case of the former example, the duty is 61.3 once every four cycles of the timer.
From 28% to 61.718%, in the case of the latter example, 61.328% and 61.718 per one cycle of the main routine.
718%, and the flow rate of the ISC air supplied through the ABV 13 also periodically fluctuates in accordance with these changes in duty.

However, the intake time constant of the engine is sufficiently large, and the air supplied through the ABV 13 receives frictional resistance between itself and the side wall of the intake passage due to its own viscosity.
As a result, the fluctuation in the flow rate of the ISC air due to the change in the drive duty is averaged during the passage through the suction passage. Therefore, at the time when the ISC air is supplied into the cylinder of the engine, the flow rate of the ISC air is set to 61.426% [61.42%] in the case of the former example.
6 = (61.328 × 3 + 61.718 × 1) / 4], and in the latter case, 61.523% [61.523 = (61.328 × 1)
2 + 61.718 × 2) / 4].

That is, since the drive duty is 8-bit data, the drive duty can be set only at a resolution of 1/256 (= 0.391%). As in the case of setting as 10-bit data, 1/1024 (=
It is possible to control the duty of the ABV 13 with a resolution of 0.098%).

Therefore, as shown in FIG. 3, the engine speed during idling controlled by the flow rate of the ISC air can be set finer than when the duty control of the ABV 13 is performed simply by using 8-bit data. . For example, the control amount of the engine speed per bit is 50 rpm in the conventional duty control using 8-bit data as it is, whereas it can be controlled in units of 12 rpm in the duty control according to the present solenoid valve drive control device. You can.

As described above, according to the solenoid valve drive control apparatus as one embodiment of the present invention, even when the CPU of the ABV drive driver 5 has only the 8-bit resolution, the least significant bit of the 8-bit data is used. By controlling the pattern, the time average is 10%
AB with the same resolution as when set as bit data
Since the duty of the V13 can be controlled, there is an advantage that fine idle speed control can be performed by the existing CPU without increasing the cost due to replacement with a high-resolution CPU or the like.

The present invention is not limited to the above-described embodiment. For example, as long as fluctuations in the flow rate of ISC air can be absorbed, the bit number n of the CPU of the ABV drive driver 5 and the target duty Can be set arbitrarily with the number of bits m. That is, when the CPU of the ABV drive driver 5 has n bits, the target duty is set to n + m bits, and the least significant bit of the drive duty set based on the upper n bits of the target duty is changed to the lower m bits of the target duty. Pattern control may be performed accordingly.

In this case, when viewed on a time average, n +
1/2 ^{n + m in the same way} as when set as m-bit data
The duty control of the ABV 13 can be performed with a unit resolution. Further, in the above-described embodiment, the present solenoid valve drive control device is provided with the lean burn engine A
Although the description has been given of the case where the BV is configured as a BV, the present invention is not limited to this, and may be applied to a solenoid valve that controls the flow rate of a fluid flowing in another fluid flow path by duty control. In the form,
Although the idling time has been described, the present invention is not limited to this, and it is of course possible to apply the present invention to a solenoid valve controlled according to the target air flow rate and the target rotation speed during normal running.

[0036]

As described above in detail, according to the solenoid valve drive control device of the present invention, when the solenoid valve interposed in the fluid flow path is opened and closed by duty control, the solenoid valve is driven in a plurality of continuous control cycles. The drive duty is set so that the average value of the plurality of drive duties set respectively corresponds to the target flow rate of the fluid, and the duty is controlled according to the drive duty set in this manner. Even when the fluid flow rate in the cycle cannot be controlled with strict accuracy with respect to the target flow rate, there is an advantage that a flow rate equal to the target flow rate can be flowed when time averaged in a plurality of continuous control cycles.

Therefore, even if the control signal output means has a low-resolution CPU that cannot control the fluid flow rate in each control cycle with strict accuracy with respect to the target flow rate, the high-resolution CPU can be used. There is an advantage that it is possible to perform the same flow control as in the case of having the above.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of a solenoid valve drive control device as one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a control pattern according to a solenoid valve drive control device as one embodiment of the present invention.

FIG. 3 is a diagram for explaining an effect when the solenoid valve drive control device as one embodiment of the present invention is applied to an ABV of a lean burn engine.

FIG. 4 is a schematic diagram showing a configuration of a lean burn engine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control means 2 target idle speed setting means 3 target duty setting means (target flow rate setting means) 4 drive duty setting means 5 ABV drive driver (control signal output means) 6 pattern control means 13 ABV (solenoid valve)

Continuing from the front page (72) Inventor Kenji Watanabe 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Kazuhiro Okuno 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation In-house (72) Inventor Kenji Goto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation F-term (reference) 3G301 HA16 JA00 JA20 KA07 LA04 LC01 LC10 MA01 MA11 NA01 ND02 ND41 PA11Z PA14Z PA15A PA17Z PB03A PD03A PE01A PE01Z PE03Z PE08Z PF08Z PF13Z

Claims (1)

[Claims] 1. A solenoid valve drive control device comprising: a solenoid valve interposed in a fluid flow path; and control means for driving the solenoid valve to open and close by duty control. A target flow rate setting means for setting a target flow rate of the fluid flowing therethrough; and a drive duty setting and updating a drive duty of the solenoid valve at a predetermined control cycle so as to correspond to the target flow rate set by the target flow rate setting means. Setting means; and control signal output means for outputting a control signal for duty-controlling the solenoid valve in accordance with the drive duty set by the drive duty setting means. The average value of the plurality of drive duties respectively set in the control cycle of As will be those response, and performs the setting of the drive duty solenoid valve drive control device.