JPS59115445A - Electronic control for linear solenoid type idle-speed control valve of engine equipped with supercharger - Google Patents

Abstract

PURPOSE:To prevent the hunting phenomenon of a control valve by controlling the valve in the operation condition where an engine load is brought close to a set value so that the stability of the operation can be improved, in electronic control of the captioned valve. CONSTITUTION:The idle revolution number is feedback-controlled by allowing the driving current having a duty ratio corresponding to the difference between the aimed idle revolution number of an engine and the revolution number at present to flow in an idle speed control valve 50, when the engine is in idle operation. When an engine load is a set value or more, conduction to the valve 50 is suspended, and the valve 50 is perfectly closed to prevent the counterflow of the supercharged air in an idle-speed control passage 48. When the engine load exceeds the set value, the lapse of a prescribed time from the above-described time is calculated, and before the prescribed time lapses, the driving current having the duty ratio corresponding to the engine operation condition is introduced into the valve 50, and after the prescribed time lapses, the conduction of the driving current is suspended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the control of the intake air amount of an automobile engine, particularly to the control of the intake air amount during idling operation, and more specifically to a supercharging compressor for a supercharged engine/engine. The present invention also relates to a method for electronically controlling a nearnoid type air control valve (idle speed control valve) installed in an idle air bypass passage that bypasses a throttle valve.

Electronically controlled fuel injection systems (EFIs) can control the air-fuel ratio of the combustion mixture according to various requirements, so today they are used as fuel supply systems for automobile engines from the viewpoint of purifying exhaust gas and improving fuel economy. It is often used in place of a vaporizer. In an EFI device called the L-Jetronic method, the amount of fuel to be injected is calculated by the device's microcomputer according to the amount of intake air measured by an air flow meter installed in the intake system, and a predetermined amount of fuel is delivered to the injector. is injected into the intake air to form a combustion mixture. The amount of intake air is controlled by a throttle valve linked to the vehicle's access pedal. The idle speed of the engine is determined by the amount of intake air flowing through the gap between the throttle valve and the throttle body when the throttle valve is fully closed. As the engine operates for a long period of time, dust adheres to this gap, so the amount of intake air during idling decreases over time, and as a result, the idle speed of the engine decreases. The idle speed may change over time as the new engine finishes its break-in and the engine's internal resistance decreases.

Furthermore, in vehicles equipped with an IC, FML driver, torque converter, power steering, etc.

When operating these devices, the total amount of air at idle must be increased. Therefore, in conventional EFI equipped engines, an idle air bypass passage is provided to bypass the throttle valve.

An air control valve is installed in this bypass passage, and by controlling the operation of this air control valve, air intake during idling can be improved!
All adjustments are made to control the idle speed to the target value. In this specification, such an idle air bypass passage is referred to as an "idle speed control passage",
The air control valve will be simply referred to as an "idle speed control valve" or simply rIscVJ. There are three types of conventionally used 15CVs: a negative pressure operated type, a step motor type, and an on/off type with a linear solenoid. The present invention relates to a beam near solenoid type l5CV, and this type of l5CV is an electronic control unit (E) mounted on an automobile.
It is turned on/off by being supplied with a pulsed drive current from the CU.

The flow rate of idle air passing through 15CV is V within a unit time.
C is the percentage of time that pulsed current is actually supplied.
It is proportional to the duty ratio. Therefore, if the duty ratio is calculated to an appropriate value by the micro combinator of the electronic control unit (E'CU), the idle speed can be controlled to the target value.

In engines with EFI systems equipped with a supercharger, such as a turbocharger, the intake of the idle speed control passage is used to prevent oil from the supercharger compressor from contaminating the 15CV.

Provided upstream of the compressor. That is, this passage can be installed to bypass both the compressor and the throttle valve.
The outlet of the passage is located downstream of the throttle valve. With this arrangement, when supercharging.

Even though there is a positive pressure downstream of the throttle valve and thus a positive pressure acts on the outlet of the idle speed control passage, a negative pressure acts on the intake of that passage because it is upstream of the compressor. Therefore, during supercharging, supercharging air flows backward through the idle speed control passage, reducing the supercharging effect. Therefore.

Conventionally, in a supercharged engine, the engine load is detected, and when the load exceeds a set value, the l5CV is controlled to be fully closed.

However, when the vehicle is operated under engine operating conditions where the engine load approaches the set value, l5
The CV turns on and off, causing a hunting phenomenon. As a result, the airflow flowing through the idle speed control passage is interrupted more frequently than necessary, causing pulsations in the intake airflow throughout the intake system. This pulsation causes overshoot or undershoot of the measuring plate of the air flow meter, resulting in inaccurate measurement of the intake air amount and fluctuations in engine output and ignition timing. Moreover, if the l5CV turns on and off unnecessarily, its durability will be adversely affected. Furthermore, there is generally a slight delay between the time the turbocharger starts operating and the time the boost pressure acts downstream of the throttle valve, so even if the engine load exceeds the set value, it is not necessary to fully close the 15CV immediately. None.

The present invention has been devised in view of the paper problems of the prior art VC, and is capable of improving the stability of operation of a linear solenoid type idle speed control valve under engine operating conditions where the engine load approaches the set value. It is an object of the present invention to provide an electronic control method for an idle speed control valve.

For this reason, the present invention detects the engine load and compares it with a set value in the above-mentioned electronic control method for the Tallinia solenoid type idle speed control valve, and when the engine load exceeds the set value, the set value is set. Measure the elapse of a predetermined time from the time when the speed exceeds the limit, and before the predetermined time elapses, a drive current with a duty ratio according to the engine operating conditions is applied to the idle speed control valve, and after the predetermined time elapses, the drive current is stopped. The feature is that the idle speed control valve is closed.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an electronically controlled fuel injection engine equipped with an idle speed control valve to which the method of the present invention can be applied. The engine intake system includes an air flow meter housing 10 connected to an air cleaner (not shown). First intake pipe 12. Compressor housing 16 of turbocharger 14. Second suction pipe 1 g, throttle body 20. Surge tank 22. Intake manifold 24. It consists of an intake boat 26, and an injector 28 is installed in the intake manifold 24 for each cylinder. The injector 28 is connected to a pressurized fuel supply system (not shown) and is connected to an electronic control unit (ECU) 3.
The valve is opened in response to a pulse signal output by 0, and a predetermined amount of fuel can be injected into intake air to form a combustion mixture.

The throttle body 20 is provided with a throttle valve 32 that is linked to the accelerator pedal of the vehicle.

A throttle position sensor 34 having a plurality of contacts is connected to the shaft of the throttle valve 32, and a signal corresponding to the throttle opening is sent to an electronic control unit.
ECU) 30.

The air flow meter housing 10 has an intake air flow rate of tti.
A measuring plate 36 is provided, and the latter is connected to a potentiometer-type intake air amount sensor 3B so that it can output a signal '1EcU30 in accordance with the intake air flow rate.

A turbocharger 14 is located downstream of the exhaust manifold 40.
A turbine housing 42 is installed, and as the exhaust turbine 44 rotates, a compression turbine 46 rotates to pressurize intake air and supercharge the engine.

An idle speed control passage 48 is provided between the first intake pipe 12 and the surge tank 22, so that even when the throttle valve 32 is fully closed, the air necessary for idling the engine bypasses the throttle valve 32 and starts the engine. is being supplied to. This idle speed control passage 48 is provided with a near solenoid type on/off air control valve, that is, an idle speed control valve (l8CV) 50.
As is well known, the CV 50 is opened and closed by a nozzle-shaped drive current output from the ECU 3O.

The distributor 52 is provided with a known rotation angle sensor 54, which can output a signal to the ECU 3O in accordance with the angular position and rotational speed of the engine crankshaft. Further, a rotating permanent magnet 58 with a protrusion is attached to the speed cable 56 of the vehicle so as to be able to rotate integrally therewith, and the rotation of this magnet 58 causes a cooperating reed switch 60 to open and close. This magnet 58 and reed switch 60 constitute a vehicle speed sensor 62, which outputs a signal according to the vehicle speed to the ECU 3O.

FIG. 2 is a block diagram of the electronic control unit (ECU) 30 shown in FIG. 1, and ECU 3O is a program-controlled microcomputer. Electronic control unit (1
", CU) 30 includes a microprocessor LMPU) 70 that performs various arithmetic processing including calculation of the duty ratio of the engineering SCv, which will be described later, and a Luread Only Memory! J that stores arithmetic processing programs and arithmetic constants. (ROM)7
2, and a random access memo consisting of a non-volatile storage section and a volatile storage section! It consists of a RAM (RAM) 74 and a clock 76 that generates various clock signals. MPU
70, ROM 72, and RAM 74 are connected to each other by a common bus 78, and a clock 76 is connected to M)'U 70 and sends a clock signal directly to the MPU 70.

The analog signal from the air flow meter 38 is sent to the buffer 8.
0 and A/D converter 84 via multiplexer 82
The signal is input to the I/C, converted into a digital signal, and read into the MPU 70 via the input/output port 86 and the common bus 78.

The signal from the throttle position sensor 34 is read into the MPU 70 via the input port 88i.

Signals from vehicle speed sensor 62 and rotation angle sensor 54 are read into MPU 70 via shaping circuit 90 and input port 88, respectively.

The MPU 70 calculates the duty ratio of 15CV by performing calculation processing to be described later in accordance with a program stored in the ROM 72 based on the data read from each sensor and stored in the RAM 74. The obtained duty ratio is transferred to a register in the MPU 70 in the same way as in the conventional method, and by counting down with the clock signal from the clock 76, it is driven as a pulse signal with the desired duty ratio via the output capo 190'. The signal is sent to circuit 92, where it is not amplified and supplied to l5CV50 in the form of a driving current.

Next, an arithmetic processing program for carrying out the method of the present invention will be described with reference to the flowcharts of FIGS. 3 and 4.

FIG. 3 is a flowchart of a load determination routine for determining whether or not the engine load exceeds a set value and for measuring the time period after the set value has been exceeded.
7L! ,! Repeated for each IQ. In step 101,
The intake air amount Q/N per engine rotation determined from the intake air amount Q detected by the air flow meter 38 and the engine rotation speed N detected by the rotation angle sensor 54 is set to a set value, for example, 0.55 (t/ The engine load is determined by comparing it with rev). Q/N≧0.
In the case of 55.

Assuming that the engine load is constant, a counter Cvc'l' is added in step 102. This counter C is R
It can be configured using a predetermined area of AM74. '
/N≧0.55, step counter 103
Set the counter to 10. 4m! In the next step 101 repeated after l&+, if Q/N≧0.55, 11@ is further added to the previous value of counter C. In this way.

As long as the condition of Q≧0.55 continues, the value recorded in the counter C increases by 111 every 4 m5ec. Therefore, when 1 second has passed since Q/N≧0.55, the recorded value of counter C is 15ee/4 m sec =
It should be 250.

FIG. 4 is a flowchart of a routine for calculating the duty ratio of the l5CV. This duty ratio calculation routine is an interrupt routine started by a signal from the rotation angle sensor 54, and is executed every revolution of the crankshaft. It is something. In step 201, the learned value of the duty ratio recorded in the nonvolatile RAM of the RAM 74 in the previous routine is determined. is read and moved to volatile RAM. Step 202 is a step for determining whether or not the engine is under conditions that require feedback control of l5CV50, for example, starting inch.

Determine engine coolant temperature, vehicle speed, throttle opening,
When the starter switch is OFF, the cooling water temperature is above the set value, the vehicle speed is zero, and the throttle valve is fully closed, the process proceeds to step 203 and subsequent steps to perform feedback control of l5CV50. When the starter is operating, when the cooling water temperature is below the set value, when the vehicle speed is high, and when the throttle valve is open, l5CV5 is activated in steps 301 and below.
0 is oven loop controlled.

If the feedback condition is met.

In step 203, a target idle rotation speed NF of the engine is selected depending on the operating state of accessory devices such as an air conditioner sonar and a torque converter. That is, when the compressor of the near conditioner is driven or when the torque converter is in the drive range, the engine load at idle changes, so a different target idle rotation speed NF is selected.

In step 204, the difference INE-NF'l between the current engine speed NE and the target engine speed NF is calculated.

In order to feedback-control l5CV50 by proportional-integral operation based on INE-NFI obtained in this way,
In steps 205 to 211, a procedure for calculating the following equation is performed.

D=DI+DP+DT ・・・・・・・・・(1)
Here, I passed 1 to DFiISCV50! The final duty ratio of the flowing pulse current, D is the integral term of the duty ratio,
DP is a proportional term and DT is an expected term. The reason why the integral term DI is used is to take the duty ratio of the previous routine (as mentioned above, the routine in Figure 4 is executed every revolution of the crankshaft) and use it as a starting point to correct the duty ratio. The proportional term DP is used to quickly recover when the control target rotation speed is large and overshoots or undershoots, and the prospective term DT is used when the load of the near conditioner, torque converter, etc. This is to immediately bring the rotational speed close to the target value when the engine is applied.

That is, in step 205, I obtained in step 204 is
Based on NF-NFI, the correction amount ΔDI of the integral term DT is RO
Read from M72. For this reason.

A map as shown in FIG. 5(a) is coded and stored in the ROM 72 in advance.2For example, if NE is 69
0 (rT)m) and NF is 700 (rPm):c Therefore, when INE-NFl = 10 (rpm), △
D1 can be 0.02 (%).

In step 206, the correction amount △D-work is added to the integral term DI of the previous routine to obtain the current DI (D-work ← D-work + △
D Engineering).

Next, in step 207, the I obtained in step 204 is
The proportional term DP is read from the ROM 72 based on NID-NFI. For this purpose, a map shown in FIG. 5(b) is encoded and stored in the ROM 72 in advance. This map can be set, for example, so that Dp is 0.5 (%) when INE-NFl=1oo (rpm). As is clear from comparing the maps in Figures 5(a) and (b), the DP map shown in Figure 5(b) is
INE is larger than the △DI map shown in Figure (a).
- has a linear portion over the range of NFI. Therefore, the △D process is suitable for slightly correcting DI, and DP
is the deviation between the current rotation speed and the target rotation speed (i.e., IN
This is suitable for quickly correcting the duty ratio when the E-NFI) is large.

In step 208, depending on the operating state of the near conditioner and the shifting state of the torque converter.

The prospective term DT is read from a similar map stored in the ROM 72 in advance.

In step 209, D + DP is calculated and the sum is the learned value of the duty ratio. (D(,4-D1+D
p). Then, in step 210, this learned value Do is stored in a predetermined area of the non-volatile RAM of the RAM 74, and the previous routine is repeated. is updated. In this way, non-volatile RA
The learning value stored in M. is used during open loop control, which will be described later.

Next, in step 211, calculation of equation (1) is performed.

The obtained final duty ratio is determined by MP in step 212.
Moved to register U70.

Next, the calculation program for the oven loop will be described. When it is determined in step 202 that the feedback condition is not satisfied, the process proceeds to step 301. In step 301, it is determined whether the value of the counter C in the load determination routine shown in the flowchart of FIG. Determine. If C≧250 (if 1 second or more has elapsed), the process proceeds to step 302, and the deity ratio is set to 0 (%). This is I5CV
50 is closed at all times.

If C≧250 (that is, one second has not elapsed), the process proceeds to step 303, where it is determined whether the engine cooling water temperature is below a set value (for example, 70° C.).

If the water temperature is higher than the set value, in step 304, the learned value of the previous routine at the time of feedback is used as the current duty ratio (D-Do). Like this.

During feedback control [RAMK recorded learning value].

By using this as a duty ratio during open-loop control, it becomes possible to perform learning control on l5CV, improving control during open-loop control.

If the water temperature is below the set value, proceed to step 305;
[)+l)o+5(@).The reason for adding 5ch to the learning value Do in this way is to increase the amount of intake air when the engine is cold.

Next, in step 306, it is determined whether the starter is on, and if YES, the duty ratio is set to 100 (%) in step 307 (D+100). This is ISCV
50 means that the valve is always open.

This is to supply more air since the required air amount is large when the engine is started. Above steps 301-30
The duty ratio obtained in step 7 is converted to MP in step 212.
Moved to register U70.

Final step 21 of the duty ratio calculation routine described above
In step 2, the values of the D and T ratios stored in the register of the MPU 70 are used to form a primary pulse signal. That is,
A clock signal is output from the clock 76 to the register every unit time, which is formed by dividing the pulse width of one cycle of the pulse signal output by the register into a large number of parts, and the value of the duty ratio stored in the register is calculated every unit time. will be counted down. During this time, as long as the value in the register exists, the register outputs an ON pulse, and when the register becomes zero, the ON pulse ends and one cycle of the pulse signal ends.

This pulse signal is sent to the drive circuit 92 via the output port 90.
The driving circuit amplifies the pulse signal and sends it to the l5CV50 in the form of a driving pulse current to open and close the l5CV. Therefore, since the driving pulse current has the duty ratio calculated by the routine shown in FIG. 4, 15CV is also 0N10FF controlled with the desired duty ratio.

As is clear from the above, the present invention detects the engine load and compares it with a set value when electronically controlling a supercharged engine near solenoid idle speed control pulp. When the set value is exceeded, the passage of a predetermined time from the time when the set value is exceeded is measured, and before the predetermined time elapses, a driving current with a duty ratio according to the engine operating conditions is supplied to the idle speed control pulp, and after the predetermined time elapses, the duty ratio is increased. Since the drive current supply is stopped and the idle speed control valve is fully closed when the ratio is set to 0, the idle speed control valve is no longer necessary even under engine operating conditions where the engine load approaches the set value. There is no on/off operation, and the operation can be stabilized. The graph in Figure 6 shows this,
According to the method of the present invention, in the A region and the B region where the engine load exceeds the set value and the supercharger operates, the A region where the predetermined time (for example, 1 second) does not elapse after the engine load exceeds the set value. In this case, the idle speed control valve is not fully closed, but is only fully closed within a range after a predetermined period of time has elapsed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an engine to which the method of the present invention is applied;
FIG. 2 is a block diagram of the electronic control unit. FIG. 3 is a flowchart of the load routine, and FIG. 4 is a flowchart of the duty ratio calculation routine. FIG. 5(a) is a map of the correction component ΔD of the integral term D. FIG. 5(b) is a map of the expected term DP, and FIG. 6 is an explanatory diagram showing the control mode of the idle speed control valve with respect to engine load fluctuations. 14...Turbocharger. 30...Electronic control unit (ECU). 32... Throttle valve. 48... Idle speed control passage. 50...Idle speed control valve (IS
CV).

Claims (1)

[Claims] In fully opening and closing the idle speed control passage that bypasses the supercharging compressor and throttle valve of a supercharged engine, or electronically controlling the near solenoid type idle speed control valve, when the engine is idling, the engine A drive current with a duty ratio according to the difference between the target idle speed and the current speed is applied to the idle speed control valve to feedback control the idle speed, and when the engine load exceeds the set value, the idle speed is adjusted. An engine linear solenoid type with a supercharger, which stops the flow of drive current to the control valve and fully closes the idle speed control valve to prevent supercharged air from flowing back into the idle speed control passageway. In electronic control method of idle speed control valve. (b) Detect the engine load and compare it with the set value. (b) When the engine load exceeds the set value, measure the passage of a predetermined time from when the set value was exceeded. (-C Before the elapse of a predetermined period of time, a drive current with a duty ratio according to the engine operating conditions) is applied to the idle speed control valve. (2) Stop the supply of drive current after a predetermined period of time has elapsed. An electronic control method for a solenoid type idle speed control valve for an engine with a supercharger, which is characterized by: