JPH0799092B2 - Supercharging pressure control device for internal combustion engine with supercharger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for controlling supercharging pressure of an internal combustion engine with a supercharger.

[Conventional technology and problems]

It is known to supercharge an engine by an engine-driven supercharger such as a roots blower provided in the intake system of the engine. 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.

This bypass control valve controls the degree of supercharging when the supercharger is rotating, and is normally a pressure operated type. The rising characteristic of supercharging can be changed by controlling the pressure introduction speed of the bypass control valve. In the system described above, when the engine load increase rate for controlling the rise of supercharging that matches the acceleration state is large (that is, during rapid acceleration), the boost pressure is rapidly increased, and the load increase rate is increased. It has been proposed to perform a gradual boost pressure increase at a small time (that is, at the time of gentle acceleration). (Japanese Patent Application No. 61-3640) However, in the above mechanism, if the switching point from slow supercharging to rapid supercharging is set low so as to obtain the desired acceleration performance after warming up, supercharging from the low load side during cold will occur. Since it begins, when the engine is accelerated during cold weather, the smoldering phenomenon of the spark plug easily occurs. This is because an increase in the fuel amount due to supercharging from the low load side promotes the rich concentration in the vicinity of the spark plug.

It is an object of the present invention to provide an improved supercharging pressure control device which can prevent smoldering of a plug without deteriorating the supercharging response during cold working.

[Means for solving problems]

According to the present invention, in order to solve the above-mentioned object, a supercharger driven by an engine is arranged in an engine intake passage, and a bypass connecting an intake passage upstream of the supercharger and an intake passage downstream of the supercharger is provided. In an internal combustion engine in which a bypass control valve is arranged in the bypass, an engine state determination means for determining whether the engine is in a cold state or a warm state, and an increase rate of the engine load are larger than a set value. Sometimes the bypass control valve is closed rapidly, and when the increase rate of the engine load is smaller than the set value, the bypass control valve is slowly closed, and when the engine is cold, the engine warms up. And a set value changing means for increasing the set value as compared with when in the state.

〔Example〕

Referring to FIG. 1, 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 an electromagnetic clutch 30, and power is transmitted to an input pulley 32 of the electromagnetic clutch 30 from a crank pulley 36 of the engine via a transmission belt 34. If you connect this electromagnetic clutch 30 while the engine is running, the turbocharger
Although 26 pumps in intake air, the engine is not actually supercharged before bypass 28 is closed.

FIG. 2 shows a functional schematic diagram of the supercharging pressure control device according to the present invention. This control device is composed of an engine state determination means 5, a set value conversion means 3 and a bypass control means 1.
The engine state determination means 5 includes, for example, a water temperature sensor 38 that can detect the temperature of cooling water for the engine.

The bypass control means 1 comprises a pressure responsive bypass control valve 40 installed in the bypass 28 and a bypass control valve drive means for driving the bypass control valve 40. In the embodiment shown in FIG. The valve driving means includes a signal port 42 provided in the intake passage 16 for obtaining the operating pressure of the control valve 40, an electromagnetic switching valve 44, pressure transmission pipes 46 and 48, and an ECU 22.
Composed of and.

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 opens the bypass 28 when negative pressure is applied to the pressure chamber 54. .

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 and the atmospheric pressure port 66, respectively. A throttle device 64 with a check valve is provided in the pipe line 48 so that the transmission of the operating pressure to the signal port 42 and the pressure chamber 54 is delayed. This switching valve 44 is an ECU
It is controlled by 22 and it is the second when energized (ON state).
The port 60 is connected to the outlet port 62, and the first port 58 is connected to the outlet port 62 when not excited (OFF state).

The ECU 22 controls the process pressure by executing the supercharging pressure control routine shown in the flowchart of FIG.

This control routine is executed, for example, every 16 ms (milliseconds). When the supercharging pressure control is started in step 101, the intake air amount Q / N per engine revolution is calculated based on the intake air amount measured by the air flow meter 14 and the engine speed N in step 102. Next, at step 103, it is judged whether the Q / N value calculated at step 102 is larger than a set value (for example, 0.5 / rev) to determine whether the engine is in the accelerating state (that is, the supercharging state is Yes) or not. If the Q / N value is less than or equal to the set value in step 103, proceed to step 110 to turn off the electromagnetic clutch 30, and then proceed to step 112, the electromagnetic switching valve.
Turn OFF 44 and return to step 101 in step 113. In this case, when the engine load is small during deceleration or cruising, it is not necessary to pump the intake air by the supercharger 26, and the opening of the throttle valve 18 is small.
At this point, the intake pipe pressure is a negative pressure, and this negative pressure is applied to the pressure chamber 54 of the bypass control valve 40 via the pipe line 48. Therefore, the negative pressure is maintained in the pressure chamber 54, and the valve body
The engine is not supercharged because it moves upward and opens the bypass 28.

When the Q / N value is equal to or larger than the set value in step 103, that is, when the vehicle is in the acceleration state (supercharging state), the process proceeds to step 104, and the electromagnetic clutch 30 is turned on to start the supercharger 26. Next, step 105 is a load increase rate of the vehicle, that is, for determining whether the acceleration state is a rapid acceleration state or a slow acceleration state, in this embodiment, the opening of the throttle valve 18 It is configured to determine whether the engine load is in a rapid increase state or a gradual increase state based on the change. That is, in step 105, the speed change ΔTA of the throttle opening TA is calculated based on the signal from the throttle sensor 56. The speed change ΔTA can be obtained, for example, by calculating the difference between the throttle opening TA ₁ at the time of the previous routine execution and the throttle opening TA ₂ at the time of the current routine execution.

In step 106, the cooling water temperature THW is detected based on the signal from the cooling water temperature sensor 38. Next, at step 107, it is judged if the cooling water temperature THW is higher than a set value (for example, 40 ° C.) to judge whether the engine is cold or warm. Cooling water temperature TH
If W is less than the set value (for example, less than 40 ° C), it is determined to be in the cold state, the process proceeds to step 111, and the set value or more (for example, 40
In the case of (° C. or higher), it is determined that the engine is warmed up and the routine proceeds to step 108. In steps 108 and 111, it is determined whether or not the throttle opening speed change ΔTA calculated in step 105 is larger than the set value in each step.

According to the present invention, the set value in step 108 is set lower than the set value in step 111 (for example, 2 ° / 16 ms) in order to determine the acceleration state for the purpose of improving the supercharging response in the warm-up state. ). Meanwhile, step 1
The set value at 11 is set higher than that at step 108 for the purpose of preventing the plug smoldering phenomenon in the cold state (for example, 4 ° / 16 ms).

At step 108, Δ from the set value (for example, 2 ° / 16ms)
When TA is large, that is, in the warm-up state, for example, ΔTA
Is greater than 2 ° / 16ms and smaller than 4 ° / 16ms (hereinafter referred to as medium acceleration) or ΔTA is 4 ° / 1.
Acceleration state greater than 6 ms (hereinafter referred to as sudden acceleration state)
In either case, proceed to step 109
Is turned on and the routine returns to the main routine in step 113.
Similarly, in step 111, the set value (for example, 4 ° / 16) is set.
msTA), that is, when the cold state is in the rapid acceleration state, the process similarly proceeds to step 109. As a result, the switching valve 44 is energized and, as described above, the second inlet port
The control valve 60 is connected to the outlet port 62, and the atmospheric pressure of the atmospheric pressure port 66 is applied to the pressure chamber 54 of the bypass control valve 40.
40 rapidly closes bypass 28. 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.

On the other hand, when ΔTA is smaller than the set value in step 108, that is, ΔTA is 2 ° / 1 in the warm-up state, for example.
In the case of an acceleration state of 6 ms or less (hereinafter referred to as a slow acceleration state), and when ΔTA is smaller than the set value in step 111, that is, in a cold state, ΔTA is 4 ° / 16 ms or less in a medium acceleration state and a gentle acceleration state. In case of, step 112 respectively
Proceed to step 1 and turn off the solenoid operated directional control valve 44 (non-excitation)
Return to the main routine at 13. As a result, the switching valve 44
The first inlet port 58 of the bypass control valve 40 is connected to the outlet port 62, and the signal port 42 and the pressure chamber 54 of the bypass control valve 40 are connected via the expansion device 64. Close slowly. That is, at this time, the negative pressure applied to the signal port 42 sharply decreases due to the opening operation of the throttle 18, but since the throttling device 64 is provided between the signal port 42 and the pressure chamber 54, the pressure inside the pressure chamber 54 is reduced. The negative pressure gradually decreases. As a result, the bypass control valve 40 is
By closing 28 relatively slowly, the supercharging pressure rises relatively slowly, reducing the shock due to the plug smoldering phenomenon in the cold state and the sudden output increase in the cold / warm state, that is, the supercharging shock. It becomes possible.

The control according to the present invention described above is summarized as follows.

That is, by gradually closing the bypass passage, the effect of reducing the supercharging shock during cold and warming up and preventing the occurrence of the plug smoldering phenomenon during the cold is enhanced, and further by rapidly closing the bypass passage, improving the supercharging rise (response). That is, rapid supercharging is possible even when it is necessary to perform rapid acceleration even during cold weather, and rapid warming can be achieved during warm-up even in the medium acceleration state. In the present embodiment, as shown in the flowchart of FIG. 3, the ON / OFF switching condition of the electromagnetic switching valve 44 is controlled by a preset temperature of the cooling water temperature THW (for example, 40 ° C.). However, as shown in FIG. 4, the set value of ΔTA during the supercharging sudden change may be continuously changed according to the water temperature THW which changes every moment. However, even in this case, the cooling water temperature
The higher THW (warm-up state), the lower the set value of ΔTA to improve the supercharging response, and the lower the cooling water temperature THW (cold state), the higher the set value of ΔTA. The plug smoldering phenomenon and supercharging shock must be prevented.

[Effect of the present invention]

According to the present invention, whether the engine is in the cold state or the warm-up state and switching the closing speed of the bypass control valve depending on the increasing rate of the engine load deteriorates the supercharging response in the cold state. Without, the smoldering phenomenon of the plug can be prevented. Further, in the warm-up state in which the plug smoldering phenomenon is unlikely to occur, the supercharging response can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an engine with a supercharger including the control device; FIG. 2 is a functional schematic diagram of a supercharging pressure control device of the present invention; FIG. 3 is a supercharging pressure control routine. Flowchart diagram; FIG. 4 shows the cooling water temperature THW representing the engine state on the horizontal axis and ΔTA continuously changed according to the water temperature THW on the vertical axis.
It is a figure expressing the setting value of. 22 ... Computer, 28 ... Bypass, 38 ... Water temperature sensor, 40 ... Bypass control valve, 42 ... Signal port, 44 ... Electromagnetic switching valve, 46/48 ... Pressure transmission pipe.

Claims (1)

[Claims] 1. A supercharger driven by an engine is arranged in an engine intake passage, and a bypass connecting an intake passage upstream of the supercharger and an intake passage downstream of the supercharger is provided, and a bypass control is provided in the bypass. In an internal combustion engine equipped with a valve, an engine state determination means for determining whether the engine is in a cold state or a warm-up state, and when the increase rate of the engine load is larger than a set value, the bypass control valve is quickly activated. Bypass control valve drive means that slowly closes the bypass control valve when the increase rate of the engine load is smaller than the set value, and when the engine is in a cold state compared to when the engine is warmed up. And a set value changing means for increasing the set value.