JPH0754095B2 - Supercharging pressure control device for internal combustion engine with supercharger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a supercharging pressure control device for an internal combustion engine equipped with an engine-driven supercharger, and more specifically, to a smoldering phenomenon of an ignition plug during low temperature acceleration. The present invention relates to a supercharging pressure control device capable of preventing the above.

[Related technology and problems]

It is known to supercharge an engine with an engine-driven supercharger such as a roots blower provided in the intake system of the engine (for example, Japanese Utility Model Laid-Open No. 59-110330). An electromagnetic clutch is provided between the supercharger and the engine output section. When the electromagnetic clutch is connected, the supercharger operates to pump intake air. The intake system is provided with a bypass that bypasses the supercharger, and this bypass is provided with a bypass control valve.
When the bypass is closed while the supercharger is operating, the engine is supercharged, and when the bypass is opened, the supercharge is stopped.

Supercharging is necessary to obtain high output when accelerating the vehicle.
In order to secure the responsiveness of the engine, it is desirable to increase the boost pressure promptly during acceleration, but this has the disadvantage that the shock due to a sudden increase in output will increase. Therefore, the applicant first proposed a supercharging pressure control device that rapidly increases the supercharging pressure at the time of sudden acceleration, but gradually increases it at the time of gentle acceleration (filed on May 27, 1985). Japanese Patent Application No. 60-112033).

On the other hand, the smoldering phenomenon of the spark plug easily occurs when the engine is cold. This is because a large amount of fuel is generally supplied during cold weather and the air-fuel ratio is too rich, and during cold weather, the fuel adhering to the inner wall of the intake port does not evaporate quickly and during deceleration. This is because when the intake pipe pressure becomes negative, it evaporates rapidly and the air-fuel ratio becomes temporarily rich. When the air-fuel ratio becomes too rich in this way, the combustion of the air-fuel mixture becomes incomplete, and the smoldering phenomenon occurs in which the generated carbon adheres to the spark plug and short-circuits or stains the electrodes, resulting in misfire and incomplete combustion. .

In the supercharging pressure control device proposed in the above-mentioned Japanese Patent Application No. 60-112033, the supercharging pressure rises sharply at the time of sudden acceleration. there were.

[Object of the Invention]

An object of the present invention is to provide a supercharging pressure control device capable of preventing a smoldering phenomenon of an ignition plug during low temperature acceleration in an engine with a supercharger.

[Means and Actions for Solving Problems]

As shown in FIG. 1, the supercharging pressure control device of the present invention has means for determining whether the engine is in a cold state or a warm-up state, and, depending on the engine state at the start of supercharging. The bypass control means controls opening and closing of the bypass.

This bypass control means gradually closes the bypass at the start of supercharging when the engine is in a cold state, so that the rise of supercharging pressure becomes slow. Therefore, the fuel does not suddenly increase and the fuel is prevented from adhering to the wall surface of the intake port. When the engine is warmed up, the bypass control means quickly closes the bypass at the start of supercharging, so that the supercharging pressure immediately rises and the required rise of output is obtained.

〔Example〕

Referring to FIG. 2, the intake system of the engine 10 includes an air cleaner 12, an air flow meter 14, an intake passage 16, and a throttle valve.
It consists of 18, intake ports 20, etc. The fuel supply system includes a conventional fuel injection valve 24 that is electronically controlled by an engine control computer (ECU) 22, and after increasing or decreasing the amount of fuel according to the intake air amount measured by the air flow meter 14, if necessary. It is designed to inject into the intake port 20.

The intake passage 16 has a supercharger 26, which is, for example, a roots blower.
And a bypass 28 is provided. This supercharger is driven by the engine 10 via the electromagnetic clutch 30, and power can be transmitted from the crank pulley 36 of the engine to the input pulley 32 of the electromagnetic clutch 30 via the transmission belt 34. If this electromagnetic clutch is engaged while the engine is running, the supercharger 26
Pumps intake air, but the engine is not actually supercharged before bypass 28 is closed.

The supercharging pressure is controlled by the supercharging pressure control device of the present invention, and this control device is composed of engine state determination means and bypass control means (FIG. 1). The engine state determination means includes, for example, a water temperature sensor 38 that can detect the cooling water temperature of the engine.

The bypass control means includes a pressure responsive bypass control valve 40 installed in the bypass 28, a signal port 42 provided in the intake passage 16 for obtaining the operating pressure of the control valve 40, and an electromagnetic switching valve 44.
And the pressure transmission pipes 46, 48 and the ECU 22.

The bypass control valve 40 has a valve body 52 that opens and closes the bypass 28 in conjunction with a spring-biased diaphragm 50, and a pressure chamber 54.
When a negative pressure is applied inside, the bypass 28 is opened.

The signal port 42 is provided downstream of the throttle valve 18 so as to take out the intake pipe pressure. As is well known, when the throttle opening is small and the load is light, the intake pipe pressure at the signal port 42 becomes negative, and when the throttle opening increases with increasing load, the intake pipe pressure approaches atmospheric pressure. Throttle valve
A throttle sensor 56 for detecting the throttle opening is linked to the valve 18, and its output is sent to the ECU 22.

The electromagnetic switching valve 44 controls the intake pipe pressure applied to the pressure chamber 54 of the bypass control valve 40, and is a three-way valve having a first inlet port 58, a second inlet port 60, and an outlet port 62. The outlet port 62 is connected to the pressure chamber 54. The first inlet port 58 is via line 48 and the second inlet port 60 is via line 46.
Are connected to the signal port 42, respectively. A throttling device 64 with a check valve is installed in the conduit 48, and the signal port
The transmission of the working pressure between the pressure chamber 42 and the pressure chamber 54 is delayed. This switching valve 44 is controlled by the ECU 22 as described later, and the second port 60 is the outlet port when energized.
Connected to 62, the first port 58 is the outlet port when not excited
It is configured to be connected to 62.

FIG. 3 shows an example of the configuration of the ECU 22. As the ECU 22, a conventional microcomputer can be used. EC
U22 is central processing unit (CPU) 66, read only memory (ROM) 68, random access memory (RAM) 70, A / D converter 72, output interface
74, bus 76, etc. The ECU 22 controls the supercharging pressure by executing the control routine shown in the flowchart of FIG. Therefore, the ROM 68 of the ECU 22 pre-stores programs and data required for execution.

The control routine of FIG. 4 is executed at predetermined time intervals as an interrupt routine of the main routine executed by the ECU 22.
When an interrupt is initiated in step 101, step 1
In 02, the cooling water temperature THW is detected based on the signal from the cooling water temperature sensor 38. Next, in step 103, it is determined whether the engine is in a cold state or a warm-up state by determining whether the cooling water temperature THW is higher than a set value (for example, 30 ° C.). If the cooling water temperature is less than 30 ° C (in the cold state), proceed to step 106 and switch the solenoid valve 4
If 4 is turned OFF and the temperature is 30 ° C or higher (in the warm-up state), proceed to step 104, turn ON the switching valve 44, and then perform step 105.
Return to the main routine with.

Since the opening of the throttle valve 18 is small when the engine load is small, the intake pipe pressure at the signal port 42 is a negative pressure, and this negative pressure is the pressure chamber of the bypass control valve 40 via the pipe line 46 or 48. Applied to 54. Therefore, since the negative pressure is maintained in the pressure chamber 54 and the valve body 54 moves upward to open the bypass 28, the engine is not supercharged even if the supercharger 22 operates.

When the opening degree of the throttle valve 18 is increased upon acceleration, the intake pipe pressure at the signal port 42 changes from negative pressure to atmospheric pressure. At that time, when the engine is in a cold state, the energization of the electromagnetic switching valve 44 is stopped in step 106,
Since the signal port 42 and the pressure chamber 54 are connected via the conduit 48 with the throttle 64, the transmission of the atmosphere from the signal port 42 to the pressure chamber 54 is delayed by the action of the throttle 64, and The pressure gradually changes from negative pressure to atmospheric pressure. Therefore, the bypass control valve 40 relatively slowly closes the bypass, and the supercharging pressure rises relatively slowly.

On the other hand, when the engine is warmed up, the switching valve 44 is energized in step 104, so that the signal port 42 and the pressure chamber 54 are connected to each other through the pipe line 46 without a restriction. Therefore, when the intake pipe pressure of the signal port 42 changes from negative pressure to atmospheric pressure as the engine load increases, the atmospheric pressure of the signal port 42 is immediately applied to the pressure chamber 54, so that the bypass control valve 40 is Close bypass 28 immediately. As a result, the supercharging pressure rises rapidly, so that the supercharging response can be secured and the output required for the rapid acceleration can be obtained.

〔The invention's effect〕

According to the present invention, in an engine with a supercharger including an engine-driven supercharger and a bypass, the bypass is slowly closed at the start of supercharging when the engine is cold, so that the supercharging pressure gradually rises. It is possible to prevent excessive fuel from being supplied during cold acceleration. Therefore, it is possible to prevent the fuel from adhering to the wall surface of the intake port without deteriorating the supercharging performance in the cold state, and to prevent the smoldering of the spark plug. Further, after warming up, the bypass is closed promptly and the boost pressure rises rapidly, so that good engine responsiveness can be secured.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a supercharging pressure control device of the present invention,
FIG. 2 is a schematic diagram of an engine with a supercharger equipped with the control device, FIG. 3 is a block diagram of an engine control computer, and FIG. 4 is a flowchart of a supercharging pressure control routine. 16 …… intake passage, 22 …… engine control computer, 26 …… supercharger, 28 …… bypass, 38 …… cooling water temperature sensor, 40 …… bypass control valve, 42 …… signal port, 44 …… electromagnetic type Switching valve, 54 ... Pressure chamber, 64 ... Throttling device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naohide Izumiya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (56) Reference JP-A-57-52635 (JP, A) (JP, U)

Claims (1)

[Claims] Claim: What is claimed is: 1. An engine-driven supercharger and a bypass for the supercharger are provided in an intake system to start supercharging the engine when the engine load exceeds a predetermined value. (A) engine state determination means for determining whether the engine is in a cold state or a warm-up state, and (b) at the start of supercharging when the engine is in a cold state. A supercharging pressure control device comprising: a bypass control unit that slowly closes the bypass and promptly closes the bypass when supercharging starts when the engine is in a warm state.