JPS6113102B2 - - Google Patents

Description

Detailed Description of the Invention The present invention bypasses an exhaust gas recirculation control valve that recirculates a portion of exhaust gas to the intake system and a throttle valve when the engine intake passage is substantially fully closed to supply intake air auxiliaryly when the engine is idling. The present invention relates to an internal combustion engine configured to include an intake air amount auxiliary control valve that controls the rotational speed of the engine to an optimum value, and to control these two valves using a solenoid valve.

As an exhaust gas recirculation control means, a method is conventionally known in which a pressure-controlled exhaust gas recirculation control valve using a diaphragm is interposed in an exhaust gas recirculation passage to control the area of the passage. The signal pressure of the exhaust recirculation control valve uses pressure related to engine operating conditions, such as engine suction negative pressure, but these are affected by the characteristics of each signal pressure and do not necessarily provide the optimum exhaust recirculation rate required by the engine. It doesn't reach that point. In particular, the above deficiencies hinder precise control of the entire engine, especially in those that use recently developed electronically controlled fuel injection valves to obtain a fuel injection amount that matches the operating conditions at the time and control exhaust gas recirculation. There is a risk of

On the other hand, in recent years, for example, during engine idling, it has become necessary to perform idle rotation control characteristics in multiple stages to purify exhaust gas during idling.

In other words, in order to shorten the warm-up time and reduce the emission of harmful exhaust components, when the coolant temperature is around 0°C, the change in the idle speed relative to the coolant temperature is reduced, or after warm-up is completed, exhaust measures are taken to reduce engine heat generation. Since the amount increases and there is a risk of overheating, control is performed such as increasing the idle speed to improve cooling performance.

Therefore, it is desirable to precisely control both the exhaust gas recirculation control and the engine rotation control using electromagnetic valves and using a microcomputer in accordance with the engine operating state. Although such control cannot be carried out precisely according to the required characteristics of both the exhaust gas recirculation and the auxiliary intake air amount, it is possible to reduce the number of output bits of the computer and use the computer for other purposes. , and simplification of control, commonality of component parts of both controls, and merging of configurations, etc., it is not necessarily a good idea to rely on the above-mentioned precise control. That is, for example, JP-A-52-
The one in Publication No. 143313 uses negative pressures with different characteristics to control the exhaust gas recirculation and auxiliary intake air amount without using a microcomputer, and is greatly affected by the negative pressure characteristics. Since the controls are controlled independently of each other, there are regions where both controls are performed in parallel, making the control complex.

Therefore, in the present invention, we conducted a detailed study on the effects of exhaust gas recirculation control and auxiliary air introduction amount control on the engine, and determined the range in which each of them can be stopped. The purpose is to find the boundary between exhaust recirculation and intake air volume control, and to control only one of them under optimal conditions without using them together.

A further object of the present invention is to enable both the exhaust gas recirculation control and the intake air amount control to be performed using an extremely simple configuration consisting of a single electromagnetic valve and switching means.

That is, when the engine is idling or running at low speed and under low load, the engine tends to become unstable, fuel consumption becomes uneconomical, and emissions tend to deteriorate, and this tendency is particularly noticeable when the engine temperature is low. In such a case, it is not desirable to carry out exhaust gas recirculation, which can cause further instability of the engine.

Therefore, when the engine temperature is below a predetermined value and at low speeds and low loads, only the intake air amount auxiliary control is performed to stabilize the engine, take measures against exhaust emissions, and improve fuel efficiency, and in other engine stability regions, the intake air amount auxiliary control is performed. The purpose is to purify the exhaust gas by recirculating the exhaust gas without having to do so. At this time, the solenoid valve only needs to be controlled by a single microcomputer, which greatly simplifies the output processing means for solenoid valve control, and this frees up the layout on the IC board within the microcomputer, which has become more complex in recent years. Space can be secured for other control output processing means that tend to be used.

To this end, the present invention includes a negative pressure-responsive intake air amount auxiliary control valve and an exhaust recirculation control valve, and a single solenoid valve that controls the magnitude of the negative pressure signal introduced from the negative pressure source to the two control valves. a switching means for selectively guiding the negative pressure controlled by the single solenoid valve to the intake air amount auxiliary control valve or the exhaust recirculation control valve; and means for detecting engine operating conditions including engine temperature. Based on the detection signal from the detection means, the intake air amount auxiliary control valve is operated in the first operating state where the engine temperature is below a predetermined value and at low speed and low load, and the exhaust gas recirculation is operated in the other second operating state. A negative pressure control signal for operating a control valve is output to the electromagnetic valve, and the negative pressure is guided to the intake air amount auxiliary control valve in the first operating state, and the negative pressure is guided to the exhaust recirculation control valve in the second operating state. The configuration includes a microcomputer that outputs a signal for selectively operating the switching means.

Embodiments of the present invention will be described below based on the drawings from FIG. 1 onwards.

In an internal combustion engine 1 shown in FIG.
The fuel is supplied to each cylinder from each branch, and fuel is injected by a fuel injector 6. Here, the flow of intake air is controlled by a throttle valve 7 in the throttle chamber 4 which is interlocked with the accelerator, and the throttle valve 7 is almost closed during idling. The flow of air during idling passes through the bypass port 8 and is regulated by the idle adjuster screw 9 installed therein, and also passes through the bypass passage 10 that communicates the upstream and downstream sides of the throttle valve 7, and the air flows there. The interposed intake air amount auxiliary control valve 11 ensures the appropriate amount of air.

The intake air amount auxiliary control valve 11 is connected to the bypass passage 1
0, a diaphragm 13 connected to the valve body 12, and a negative pressure working chamber 15 equipped with a spring 14 that biases the diaphragm 13.
The amount of lift of the valve body 12 by the diaphragm 13 is changed to decrease or increase the opening degree according to the increase or decrease of the negative pressure introduced into the negative pressure working chamber 15. This negative pressure working chamber 15 communicates with the intake passage downstream of the throttle valve 7 via a constant pressure valve (pressure regulator valve) 17 through a negative pressure introduction passage 16, and a pulse solenoid valve 19 through an atmosphere introduction passage 18. It communicates with the intake passage upstream of the throttle valve 7 through the throttle valve 7. Thus, by opening and closing the pulse solenoid valve 19, the dilution ratio of the negative pressure introduced into the negative pressure working chamber 15 with the atmosphere is changed, and the time ratio of opening and closing of the intake air amount auxiliary control valve 11 is controlled. That's why.

On the other hand, the exhaust gas discharged from the internal combustion engine 1 passes through an exhaust passage 37, during which time an O ₂ sensor 3 measures the O ₂ concentration in the exhaust gas, which is closely related to the air-fuel ratio of the engine intake air-fuel mixture.
8 and reaches the catalyst 39, where the unburned components are oxidized and/or reduced.

A part of the exhaust gas is recirculated to the intake passage downstream of the throttle valve 7 via the exhaust gas recirculation passage 40, and the recirculation amount is equal to the passage opening area of the negative pressure responsive diaphragm exhaust recirculation control valve 41 installed in the passage 40. Controlled according to increase/decrease. The control valve 41 is composed of a valve body 42 interposed in an exhaust gas recirculation passage 40, a diaphragm 43 connected to the valve body 42, and a negative pressure working chamber 45 equipped with a spring 44. A negative pressure signal is introduced.

The negative pressure passage 46 is connected to the intake passage downstream of the throttle valve 7 via a constant pressure valve 47, and the engine suction negative pressure is controlled to a predetermined negative pressure by the constant pressure valve 47. This constant negative pressure is diluted to a negative pressure value depending on the engine operating condition by introducing atmospheric air through the pulse solenoid valve 49.

The above two pulse solenoid valves 19, 49 are configured so that normally closed valve bodies 19a, 49a are sucked upward as shown in the figure against spring force by supplying power to the solenoid, thereby opening the atmospheric air introduction passages 18, 48. By opening and closing the pulse solenoid valves 19, 49 depending on the presence or absence of an output pulse from the microcomputer 20, which will be described later, the negative pressure working chambers 15, 4 are opened and closed.
The degree of opening of the control valves 11 and 41 is controlled by changing the dilution ratio of the negative pressure introduced into the control valve 5 with the atmosphere.

The microcomputer 20 mainly includes a microprocessor (central processing unit) 21, a memory (storage device) 22, and an interface (input/output signal processing circuit) 23. The interface 23 includes an electromagnetic pick-up type rotation speed detection element 2 that detects the intake air amount signal detected by the air flow meter 3 or the rotation of the crank gear of the internal combustion engine.
A signal representing the engine operating state, such as the engine rotational speed signal detected in step 4, is input, and the microprocessor 21 calculates this to know the engine operating state and determines the optimal exhaust at this time, which has been stored in the memory 22 in advance. Check the reflux rate and optimal intake air amount (Table look
up) and then apply an electromagnetic pulse having a pulse width corresponding to these to the pulse solenoid valve 19 of the intake air amount auxiliary control device or the pulse solenoid valve 4 of the exhaust recirculation control device.
9 and controls the atmospheric dilution rate of the negative pressure signal by the solenoid valve 19 or 49.

Interface 2 of microcomputer 20
3 includes a water temperature sensor 25 that is attached to the internal combustion engine 1 and detects that the temperature of the cooling water is below a predetermined value, for example 40°C, and a water temperature sensor 25 that is attached to the internal combustion engine 1 and detects that the opening degree of the throttle valve 7 is below a predetermined value, for example 5°. ON and OFF signals are respectively input from a throttle switch 27 for detection and a vehicle speed switch 29 for detecting that the vehicle speed is below a predetermined value, for example 5 km/h.

These detection signals operate the above-mentioned configuration as follows.

When the internal combustion engine is cold (for example, when the cooling water temperature is below 40° C.) At this time, the engine is warming up, the engine is unstable, and the air-fuel mixture is set to be rich. Therefore, it is necessary to take measures such as reducing engine speed fluctuations in response to changes in cooling water temperature, reducing the amount of harmful exhaust gas components such as HC and CO, and shortening the warm-up time. It is appropriate to precisely control the amount of air to avoid exhaust gas recirculation, which is inconvenient to the above measures, and to improve fuel efficiency.

In response to this request, in this embodiment, the water temperature sensor 25
detects a cooling water temperature of 40°C or less, inputs it to the microcomputer 20, and sends the pulse solenoid valve 19 of the intake air amount auxiliary control device an ON-OFF time ratio according to engine operating conditions such as cooling water temperature or engine speed. (duty ratio) and at the same time sends a fully open signal to the pulse solenoid valve 49 of the exhaust recirculation control device. As a result, the intake air amount auxiliary control device controls the dilution ratio of the intake air amount auxiliary control valve 11 to the negative pressure in the negative pressure working chamber 15 by opening and closing the pulse solenoid valve 19, thereby optimizing the intake air amount for the engine operating condition. is supplied to the engine by bypassing the throttle valve 7 (fully closed state). In the exhaust gas recirculation control device, the pulse electromagnetic valve 49 is fully opened and the negative pressure signal of the exhaust gas recirculation control valve 41 becomes atmospheric pressure, so that the valve opening of the valve 41 is fully opened and exhaust gas recirculation is stopped.

The internal combustion engine is unstable even when the vehicle is running at low speed and under low load (for example, when the throttle opening is less than 5 degrees and the vehicle speed is 5 km/h, including idling), and the intake air amount control by the throttle valve opening is rough. The air-fuel ratio of the mixture is accurately controlled by compensating for the
It is necessary to improve combustion to improve output and fuel efficiency.

In this case as well, the microcomputer 20 inputting the detection signals of the throttle switch 27 and the vehicle speed switch 29 operates the intake air amount auxiliary control device and stops the operation of the exhaust gas recirculation control device, as described above.

When the internal combustion engine has come out of a cold state and is operating at high speed and high load (for example, when the cooling water temperature is 40°C or higher and the vehicle speed is 50°C).
Km/h or the throttle opening is greater than 5°) In this case, since the intake air amount is large, the effect of auxiliary control on the overall intake air amount is small, so there is no need for auxiliary control, and combustion Since the engine is stable and the engine is stable, it is appropriate to perform exhaust gas recirculation to lower the combustion temperature and reduce the amount of NOx generated.

Therefore, in this example, the pulse solenoid valve 19 of the intake air amount auxiliary control device is fully opened by the operation of the microcomputer 20 that receives input from the engine operating state detection means such as the water temperature sensor 25, the throttle switch 27, and the vehicle speed switch 29. At the same time as fully closing the intake air amount auxiliary control valve 11, a pulse signal with a duty ratio suitable for the engine operating condition is output in order to operate the pulse solenoid valve 49 of the exhaust recirculation control device, and the exhaust is at the optimum rate. Perform reflux.

Since only one of the exhaust gas recirculation and the auxiliary intake air introduction is performed in parallel, the control signal of the microcomputer 20 can be a single signal without overlapping both controls, and the control means can be simplified. At the same time, the output processing device is also simplified for single output. In this case, the solenoid valves 19 and 49 can be made common, and in the present invention, the solenoid valves 19 and 49 are made common and unified.

In the above example, the pulse solenoid valves 19 and 49 are
It goes without saying that in addition to changing the ON/OFF duty ratio, the valve opening degree may be controlled analogously.

Fig. 2 shows an example in which the constant pressure valves 17 and 47 in Fig. 1 are shared by one valve 17, and Fig. 3 shows an example in which the two solenoid valves 19 and 49 in Fig. 1 are used in a single unit in addition to Fig. 2. This is an example shared by 19. FIG. 3 shows an embodiment of the invention. The negative pressure controlled by the solenoid valve 19 is branched from the negative pressure passage 16 and transferred to a switching solenoid valve (switching means) 5.
The control signal is supplied as a negative pressure to either the intake air amount auxiliary control valve 11 via the negative pressure passage 16a selected by No. 1 or the exhaust recirculation control valve 41 via the negative pressure passage 46a. Therefore, the switching solenoid valve 51
The microcomputer 20 performs the switching operation and the switching control of the pulse signal output for controlling the amount of intake air given to the pulse solenoid valve 19 or the output of the pulse signal for controlling the amount of exhaust recirculation.

The embodiment shown in FIG. 4 is one in which the constant pressure valve 17 and the pulse solenoid valve 19 shown in FIG. 3 are integrated.

Although a vehicle speed switch is used as the vehicle speed sensor in the above embodiment, the present invention is not limited to this, and it goes without saying that other methods may be used, such as detecting the vehicle speed based on a combination of engine speed and shift position.
Also, 9' is a throttle valve 7 that supplies the air necessary for warm-up operation.
This is an air regulator that bypasses the air and supplies it to the engine combustion chamber.

As described above, according to the present invention, when the engine is cold and the engine is running at low speed and under low load, the amount of intake air is accurately controlled in addition to the control by the throttle valve, thereby stabilizing the engine, increasing output, and in particular, improving HC. It is possible to simultaneously purify the exhaust gas with respect to CO and improve fuel efficiency, and in other areas, purify the exhaust gas with respect to NOx in particular by recirculating the exhaust gas.

Furthermore, since the above control can be performed by operating a solenoid valve using a microcomputer, optimal control can be performed that is suitable for the engine operating state without being affected by characteristics such as load signals.

Furthermore, since only one of exhaust gas recirculation and auxiliary air introduction needs to be controlled reliably, it is possible to configure a single solenoid valve, simplifying the overall configuration, and making it possible to control the solenoid valve in a single manner. This can be done using signals, which makes the control extremely simple, making it possible to simplify the control means of the microcomputer, reduce the number of output processing devices, and thereby obtain margin for other controls.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of an internal combustion engine according to the present invention, and FIGS. 2 to 4 are system diagrams showing other embodiments. 1... Internal combustion engine, 7... Throttle valve, 10...
...Bypass passage, 11...Intake air amount auxiliary control valve, 16, 46...Negative pressure introduction passage, 17, 47...
...Constant pressure valve, 19,49...Pulse solenoid valve, 20...
...Microcomputer, 25...Water temperature sensor,
27...Throttle switch, 29...Vehicle speed switch, 51...Switching solenoid valve.

Claims (1)

[Scope of Claims] 1. A negative pressure-responsive intake air amount auxiliary control valve that is provided with a bypass passage that communicates the upstream and downstream sides of the throttle valve in the engine intake passage and controls the amount of air that passes through the bypass passage; a negative pressure-responsive exhaust recirculation control valve that controls the amount of exhaust gas recirculated through an exhaust recirculation passage that communicates the passage with the intake passage;
A single solenoid valve that controls the magnitude of a negative pressure signal introduced into one control valve, and the negative pressure controlled by the single solenoid valve is selected as the intake air amount auxiliary control valve or the exhaust recirculation control valve. means for detecting engine operating conditions including engine temperature;
Based on the detection signal from the detection means, the intake air amount auxiliary control valve is operated in the first operating state where the engine temperature is below a predetermined value and low speed and low load, and the exhaust recirculation control valve is operated in the other second operating state. outputting a negative pressure control signal for operating the valve to the electromagnetic valve, and switching the negative pressure to the intake air amount auxiliary control valve in the first operating state and to guide the negative pressure to the exhaust recirculation control valve in the second operating state; An internal combustion engine comprising: a microcomputer that outputs a signal for selectively operating the means. 2. Claim 1, wherein the negative pressure signal to be controlled by the solenoid valve is a negative pressure signal obtained by taking negative pressure from a single negative pressure source and making it constant by a constant pressure valve.
Internal combustion engines as described in section.