JPH04237849A - Idling speed controller for internal combustion engine with assist air feeder - Google Patents

Abstract

PURPOSE:To keep off any drop in engine speed at the time of idling by way of utilizing an assist air feeder which accelerates an atomization of injection fuel with assist air fed to the vicinity of a nozzle of a fuel injection valve. CONSTITUTION:In general, engine speed at the time of idling is controlled by intake air by controlling the opening of an idle control valve 24 installed in a bypass passage 23 bypassing a throttle valve 3. In addition, when the engine speed is temporarily dropped by load application or the like at the time of idling, a span of valve opening time of an assist air control valve 16, feeding assist air for atomizing injection fuel in and around a nozzle 5c of a fuel injection valve 5, is prolonged to some extent for increment, through which an air quantity to be fed for combustion is increased, improving the extent of responsiveness, thus any possible drop in engine speed is eliminated earlier.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention stabilizes the engine speed during idling by using a system that supplies part of the intake air as assist air to the vicinity of the nozzle hole of a fuel injection valve provided in the intake passage. , relates to an idle speed control device for an internal combustion engine having an assist air supply device.

0002

[Background Art] Conventionally, the idle speed of an internal combustion engine is controlled by providing an idle control valve in a bypass passage that bypasses a throttle valve, and controlling the opening degree of this idle control valve to feed back the idle speed. I was in control. In addition, in an internal combustion engine having an electronically controlled fuel injection device, an electromagnetic fuel injection valve is provided for each cylinder in the branch part of the intake manifold or the intake port.
Fuel injection is performed, but some are equipped with an assist air supply device to promote atomization (vaporization) of the injected fuel (
Special Publication No. 64-9465, Utility Model Publication No. 63-18767
(Refer to the publication number, etc.)

[0003] In this system, a part of the intake air is guided from upstream of the throttle valve through an assist air passage and is supplied as assist air near the nozzle hole of each fuel injection valve, and the collision of the assist air with the injected fuel causes the injection. Atomizes fuel,
This improves combustion and improves exhaust performance, etc. A system has also been proposed in which the idle speed is feedback-controlled by controlling the amount of assist air.
(See Publication No. 67).

0004

[Problems to be Solved by the Invention] However, in the conventional idle speed control device using an idle control valve, when a rotation drop occurs due to load application etc. during idling, the rotation speed control device detects the rotation drop and then stops the idle rotation speed control device. Even if the control valve is open, there is a collector volume between the idle control valve position and the intake valve position, so there is a delay before air enters the cylinder, which prevents rotational hunting. In the worst case scenario, there is a possibility that the engine may stall.

[0005] In addition, in the case of an idle speed control device using assist air, the assist air control valve is close to the intake valve, so although it is excellent in terms of responsiveness, the amount of assist air is insufficient in terms of quantity. Another problem is that it is difficult to use it to control the idle speed over the entire engine cooling water temperature range from low to high engine cooling water temperatures.

SUMMARY OF THE INVENTION In view of these conventional problems, the present invention provides an idle rotation speed control device that can improve stabilization of the rotation speed during idle in an internal combustion engine having an assist air supply device. The purpose is to

[0007]

[Means for Solving the Problems] Therefore, the present invention has an idle control valve in a bypass passage that bypasses a throttle valve in an intake passage, which is opened according to a duty ratio, and also has an idle control valve that is opened in accordance with a duty ratio. As shown in FIG. 1, an internal combustion engine has an assist air supply device that guides a part of the air and supplies it as assist air to the vicinity of the nozzle hole of the fuel injection valve provided downstream of the throttle valve for each cylinder.
The duty ratio basic control amount setting means (a) sets a basic control amount based on the engine cooling water temperature, and the duty ratio sets a feedback correction amount by comparing the engine speed and a target idle speed during idling. a feedback correction amount setting means (b), a duty ratio setting means (c) for setting the duty ratio based on the basic control amount and the feedback correction amount, and an engine speed is lower than a target idle speed, and a rotation speed sudden decrease detection means (d) for detecting a sudden rotation speed decrease state in which an amount of change in the engine rotation speed toward a decrease side is equal to or greater than a predetermined value, and clamping the feedback correction amount when the rotation speed sudden decrease state is detected. a clamping means (e) for detecting the sudden decrease in rotational speed;
Assist air increasing means (f) for increasing the amount of assist air supplied by the assist air supply device is provided to constitute an idle rotation speed control device.

[0008]

[Operation] In the above configuration, the basic control amount setting means sets the basic control amount based on the engine cooling water temperature, and the feedback correction amount setting means compares the engine speed and the target idle speed at idle. the feedback correction amount is set by the duty ratio setting means, the duty ratio is set based on the basic control amount and the feedback correction amount, and the opening degree of the idle control valve is controlled based on the duty ratio. , to control the idle speed.

When the engine speed is lower than the target idle speed and the amount of change in the engine speed toward the decreasing side is greater than or equal to a predetermined value, the rapid speed decrease state detecting means detects This is detected, and at this time, the clamping means clamps the feedback correction amount, and the assist air increasing means increases the amount of assist air supplied by the assist air supply device.

[0010] Accordingly, when the rotational speed suddenly decreases during idling, by supplying an increased amount of assist air, responsiveness is improved and a drop in rotational speed is prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system diagram of an intake system of an internal combustion engine. After passing through an air flow meter 2, air from the air cleaner 1 is sucked in under the control of a throttle valve 3 that is linked to an accelerator pedal, and reaches an intake manifold 4. Then, at the branch portion or intake port, the mixed fuel is mixed with the fuel injected from the fuel injection valve 5 provided for each cylinder, and is sucked into the cylinder of the engine.

A bypass passage 23 is formed by bypassing the throttle valve 3, and an idle control valve 24 is interposed in the middle of the bypass passage 23. The idle control valve 24 is of a rotary type, and pulse signals are sent to a valve-opening coil and a valve-closing coil (not shown) in an inverted state, and the duty ratio ( When controlling the opening degree by controlling the pulse width of the pulse signal given to the valve opening coil at a constant cycle,
The opening degree is adjusted according to the time ratio (%) of the pulse width to the period.

The fuel injection valve 5 is an electromagnetic fuel injection valve (injector) that opens when an electromagnetic coil is energized and closes when the energization is stopped, and opens when energized by a drive pulse signal from the control unit 6. The fuel in the fuel gallery 8 is injected by a fuel pump (not shown) and regulated to a predetermined pressure by the pressure regulator 7.

Here, the control unit 6 uses a built-in microcomputer to determine the basic fuel injection amount Tp=K·Q/N (K is a constant, N is an engine The rotational speed) is calculated, various corrections are made to this, and the fuel injection amount Ti=T
p COEF (COEF is various correction coefficients) is determined, and the fuel injection valve 5 of each cylinder is independently aligned with the intake stroke of each cylinder, and in detail, the fuel injection end timing is near the intake TDC. Fuel injection is performed by outputting a drive pulse signal having the pulse width of Ti so that

An assist air passage 9 is provided as an assist air supply device. The assist air passage 9 is
A portion of the intake air is guided from the assist air intake port 10 downstream of the air flow meter 2 and upstream of the throttle valve 3,
The structure is such that assist air is supplied by a pressure difference between the upstream side and the downstream side (natural assist method), and an air gallery 15 for branching is formed on the downstream side. This air gallery 15 has the same number of fuel injection valves 5 (in this example, 4 for 4 cylinders).
Assist air control valves 16 are provided, and the nozzle holes 17 of each assist air control valve 16 are connected to air inlets 21 of each fuel injection valve 5, which will be described later, through pipes 18, respectively.

As shown in FIG. 3, each fuel injection valve 5 is provided with a needle valve 5b inside a valve body 5a, and the injection hole is opened by lifting the needle valve 5b by energizing an electromagnetic coil (not shown). A cover 19 is provided surrounding the valve body 5a, and an annular passage 20 is formed between the cover 19 and the valve body 5a. Then, the pipe 18 connected to the nozzle hole 17 of the assist air control valve 16 is connected to the cover 1.
By connecting to the air inlet 21 on the side of the fuel injection valve 9, assist air is guided into the annular passage 20, and the assist air is guided by the annular passage 20 to form an annular air jet surrounding the nozzle hole 5c of the fuel injection valve 5. It is ejected from the outlet 22 and collides with the injected fuel to promote atomization of the injected fuel.

Furthermore, the assist air control valve 16 includes:
This is an electromagnetic air injection valve (injector) that has the same structure as the fuel injection valve 5, that is, it has a needle valve inside the valve body, and opens the nozzle hole and injects air by lifting the needle valve by energizing the electromagnetic coil. use. This is because it is superior in terms of responsiveness. Therefore, the assist air control valve 16 is also energized and opened by the drive pulse signal output from the control unit 6.

To explain the control of the assist air control valves 16 by the control unit 6, each assist air control valve 16 is controlled by outputting a drive pulse signal to each assist air control valve 16 in synchronization with the fuel injection of each fuel injection valve 5. The air control valves 16 are driven to open independently of each other. However, the drive pulse signal (fuel injection) to the fuel injection valve 5 of a certain cylinder
The relationship between the drive pulse signal (air injection) to the corresponding assist air control valve 16 is as shown in FIG. The valve opens when the valve is advanced.

That is, the air injection start time is calculated by advancing the fuel injection start time by a predetermined period T0, and control is performed based on this. It should be noted that the predetermined period T0 takes into consideration the response delay of air supply (due to the piping volume). Furthermore, as a control according to the present invention, the air injection end timing may be the same as the fuel injection end timing, except when this assist air is also used for idle speed control to stabilize the speed at idle. .

Furthermore, a crank angle sensor 25 for detecting the engine speed N and a water temperature sensor 26 for detecting the engine cooling water temperature are provided. Next, the effect will be explained. The control unit 6 controls the fuel injection valves 5 of each cylinder, independently of each other, to substantially synchronize the timing with the intake stroke of each cylinder.
By outputting a drive pulse signal with a pulse width commensurate with the intake air amount Q, fuel is injected using a sequential injection method.

[0021] Prior to this, the control unit 6 controls the corresponding assist air control valve at a predetermined period T0 or more after the fuel injection start time of each fuel injection valve 5 according to a flowchart to be described later. A drive pulse signal is output to the assist air control valve 16 to open the assist air control valve 16. As a result, part of the intake air can be supplied as assist air only to the fuel injection valve 5 during fuel injection near its nozzle hole 5c, and assist air can be supplied to the fuel injection valve 5 during fuel injection stop. By stopping the supply, high idle can be prevented.

Next, FIG. 5 shows idle rotation speed control using the assist air control valve 16 and the idle control valve 24.
The explanation will be based on the flowchart. In step 1 (denoted as S1 in the figure; the same applies hereinafter), a basic control amount ISCTW is searched based on a map in accordance with the engine cooling water temperature TW detected by the water temperature sensor 26.

[0023] Then, in step 2, it is determined whether or not the idle condition is satisfied. If the idle condition is satisfied, the process proceeds to step 3, but if not, the process proceeds to step 9. Here, the idle condition means that the throttle valve 3 is fully closed, the transmission is in the neutral position, or the vehicle speed is below a predetermined value. In step 3, as in step 1, the target idle speed Ns is searched based on the map in accordance with the engine cooling water temperature TW.

Then, in step 4, the engine speed N is detected based on the signal from the crank angle sensor 25. In step 5, the target idle rotation speed Ns obtained in step 3 is compared with the actual rotation speed N obtained in step 4, and if N>Ns, the feedback correction amount ISCF is decreased by a predetermined amount ΔF in step 6. Also, when N<Ns, in principle, the feedback correction amount ISCF is increased by a predetermined amount ΔF in step 8.

Then, in step 9, the opening time of the assist air control valve 16, which influences the amount of assist air, is determined by adding a predetermined value T0 to the fuel injection amount Ti, and the assist air control valve 16 is controlled. On the other hand, when N<Ns in step 5 (that is, when the engine speed N is lower than the target idle speed Ns), before step 8, in step 7, the amount of change in the rotation speed toward the decreasing side is set to a predetermined value. (If the number of revolutions before a predetermined time is Nold, then N
old −N>predetermined value), and if so, it is determined that the rotation speed has suddenly decreased, and in this case, without going to step 8, the feedback correction amount ISCF is clamped in step 10, In step 11, a correction amount C is searched based on the map according to the amount of change ΔN in the rotation speed and the difference (Ns-N) between the target idle rotation speed Ns and the actual idle rotation speed N. Here, the correction amount C increases as the rotation speed change amount ΔN increases, and the difference between the target idle rotation speed Ns and the actual idle rotation speed N (Ns
-N) is set to increase as the value increases.

In step 12, the assist air control valve 16
The amount of assist air is increased by setting the valve opening time longer than usual by the correction amount C and controlling the assist air control valve 16 (see FIG. 4). Then step 13
Then, the duty ratio ISCD is obtained by adding the basic control amount ISCTW and the feedback correction amount ISCF, and the idle control valve 24 is controlled by this duty ratio ISCD, and the routine ends.

If it is determined in step 2 that the idle condition is not satisfied and the process proceeds to steps 9 and 13,
The feedback correction amount is clamped to the previous value. Here, step 1 corresponds to the basic control amount setting means, steps 2 to 6, and 8 correspond to the feedback correction amount setting means, steps 5 and 7 correspond to the rotation speed sudden decrease detection means, and step 10 corresponds to the clamping means. Steps 11 and 12 correspond to assist air increasing means, and step 13 corresponds to duty ratio setting means.

In the above embodiment, only the natural assist method was used as the assist air supply method, but an air pump is provided in the middle of the assist air passage 9 to actively supply assist air (supercharging). It may also be applied to assist method). In addition, the assist air passage 9 is branched in the middle, and an air pump for supercharging is provided on one side, and an electromagnetic on-off valve for switching is provided on the other, so that both the natural assist method and the supercharging assist method are used. It can also be applied to things like this.

[0029]

[Effects of the Invention] As explained above, according to the present invention, during normal operation, the idle speed is controlled by the idle control valve over the entire range from low to high engine cooling water temperatures. On the other hand, due to load application during idle,
When the rotation speed suddenly decreases, increase the amount of assist air.
It is possible to avoid a drop in rotation.

[Brief explanation of the drawing]

[Figure 1] Functional block diagram showing the configuration of the present invention

[Figure 2
] System diagram of an intake system of an internal combustion engine showing an embodiment of the present invention

[Figure 3] Cross-sectional view of essential parts of a fuel injection valve with an air jet port

[Figure 4] Diagram showing the relationship between fuel injection and air injection

[
Figure 5: Flowchart of rotation speed control during idling

[Explanation of symbols]

2 Air flow meter 3 Throttle valve 4 Intake manifold 5 Fuel injection valve 5c Nozzle hole 6 Control unit 9 Assist air passage 15 Air Gallery 16 Assist air control valve 18 Pipe 22 Air outlet 23 Bypass passage 24 Idle control valve 25 Crank angle sensor 26 Water temperature sensor

Claims (1)

[Claims] Claim 1: The bypass passage that bypasses the throttle valve in the intake passage has an idle control valve that is opened according to the duty ratio, and a part of the intake air is guided from upstream of the throttle valve to each cylinder downstream of the throttle valve. In an internal combustion engine having an assist air supply device that supplies assist air near the nozzle hole of each fuel injection valve,
basic control amount setting means for setting a basic control amount for the duty ratio based on engine cooling water temperature; and feedback correction for setting a feedback correction amount for the duty ratio by comparing the engine speed and a target idle speed during idling. a duty ratio setting means for setting the duty ratio based on the basic control amount and the feedback correction amount, and the engine speed is lower than the target idle speed and the engine speed is on the decreasing side a rotational speed sudden decrease detection means for detecting a sudden rotational speed decrease state in which the amount of change in the rotational speed is greater than a predetermined value; a clamping means for clamping the feedback correction amount when the rotational speed sudden decrease state is detected; and a detection means for detecting the rotational speed sudden decrease state. An idling speed control device for an internal combustion engine having an assist air supply device, further comprising: an assist air increasing means for increasing the amount of assist air supplied by the assist air supply device.