JPH0742864B2 - 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.

[Related technology and problems]

The present invention relates to an improvement of the supercharging pressure control device proposed in Japanese Patent Application No. 60-112033 filed on May 27, 1985. FIG. 2 of the above patent application shows an engine with a supercharger, and a bypass of the supercharger is provided in the intake system. If this bypass is closed while the supercharger is operating, the engine will be supercharged, and if the bypass is opened, supercharged air will escape through the bypass to the intake side of the supercharger, so supercharging will be stopped. There is. The bypass is opened and closed by a pressure responsive bypass control valve, and the intake pipe pressure obtained from a signal port downstream of the throttle valve is used as the operating pressure of the bypass control valve. An electromagnetic switching valve is provided between the pressure chamber of the bypass control valve and the signal port so that the operating pressure can be switched according to the acceleration state. That is, during gentle acceleration, the intake pipe pressure is applied to the pressure chamber of the bypass control valve via the passage with a restriction, and the bypass control valve is gradually closed to start supercharging slowly. Is applied to the pressure chamber through a passage without a throttle, the bypass control valve is quickly closed and supercharging is immediately started.

However, the intake pipe pressure does not respond promptly to changes in the throttle valve opening, and even if the throttle valve is suddenly opened during rapid acceleration, the intake pipe pressure changes with a slight response delay. Therefore, in the method of the above patent application, there is a problem that the closing of the bypass control valve is delayed due to the response delay of the intake pipe pressure at the time of sudden acceleration, and the rise of torque is delayed.

[Object of the Invention]

It is an object of the present invention to further improve the supercharging pressure control device and further improve the rise of torque during sudden acceleration.

[Means and Actions for Solving Problems]

According to the present invention to achieve the above object, a supercharger is provided in the engine intake passage downstream of the throttle valve, and the supercharger is bypassed to connect the discharge side and the intake side of the supercharger. A bypass control valve for controlling the amount of air flowing through the bypass is arranged in the bypass to be connected, and a pressure chamber of the bypass control valve is connected to an intake passage downstream of the throttle valve to allow intake air downstream of the throttle valve into the pressure chamber. In the supercharging control device for an internal combustion engine with a supercharger, which guides the pressure in the passage, and the opening amount of the bypass control valve increases as the pressure in the pressure chamber decreases,
When the increase rate of the engine load is smaller than a predetermined set value, the pressure chamber is kept connected to the intake passage downstream of the throttle valve, and when the increase rate of the engine load is larger than the set value, the pressure chamber is kept in the atmosphere. A control means for opening the door is provided.

In this way, when the load suddenly increases (when the vehicle accelerates rapidly), the atmospheric pressure is immediately applied to the pressure chamber of the bypass control valve, so the bypass control valve is closed more quickly, and supercharging is faster. The acceleration response is started and improved.

〔Example〕

Referring to FIG. 1, the intake system of the engine 10 includes an air cleaner 12, an intake passage 14, an air flow meter 16, a throttle valve 18, etc., and a fuel supply system includes an electronically controlled fuel injection valve.
Comprising 20. The intake passage 14 is provided with a supercharger 22 composed of a roots blower and a bypass 24. The supercharger 22 is driven by the engine 10 via the electromagnetic clutch 26, and power is transmitted from the crank pulley 32 to the input pulley 28 of the electromagnetic clutch 26 via the transmission belt 30. If the electromagnetic clutch 26 is connected during engine operation, the supercharger 22 pumps intake air, but if the bypass 24 is opened, the supercharged air escapes to the suction side of the supercharger 22 via the bypass 24. Is not supercharged. The electromagnetic clutch 26 is an engine control computer (ECU) 34 including a microcomputer.
Is controlled by ON / OFF. The throttle valve 18 is interlocked with a throttle sensor 36 that detects the throttle opening, and its analog output is input to the ECU 34. The output signal of the air flow meter 16 is also sent to the ECU 34.

The bypass 24 is opened and closed by a bypass control valve 38. The control valve 38 includes a movable valve body 40 that opens and closes the bypass 24 and the valve body 40.
A diaphragm 42 interlocking with 40, a pressure chamber 44 and an atmospheric pressure chamber 46 separated by the diaphragm 42, and a return spring 48.
Have. The pressure chamber 44 is connected to the outlet port 52 of the electromagnetic switching valve 50. This switching valve 50 has two inlet ports 54,5
6 is provided so that any one of these inlet ports is selectively connected to the outlet port 52. That is, EC
When the switching valve 50 is energized by U34, the second inlet port 56
Is connected to the outlet port 52 and the
The inlet port 54 is connected to the outlet port 52.

An atmospheric pressure port 58 is provided in the intake passage 14 upstream of the throttle valve 18, and the atmospheric pressure port 58 is connected to a second inlet port 56 of the switching valve 50 by a pipe line 60. Further, a signal port 62 is provided in the intake passage 14 downstream of the throttle valve 18 so as to take out the intake pipe pressure. As is well known, the intake pipe pressure at the signal port 62 becomes a negative pressure when the opening degree of the throttle valve 18 is small, and approaches the atmospheric pressure as the throttle opening degree increases. The signal port 62 is connected to the first inlet port 54 of the switching valve 50 by the pipe 64.

According to the above configuration, when the electromagnetic switching valve 50 is energized, the atmospheric pressure of the atmospheric pressure port 58 is applied to the pressure chamber 44 of the bypass control valve 38, and the control valve 38 is closed. Pressure chamber if power is stopped
The intake pipe pressure of the signal port 62 is applied to the 44, but in this case, since the intake pipe pressure changes as described above according to the throttle opening, a negative load is applied to the pressure chamber 44 when the throttle opening is small and the load is light. When the pressure is applied and the bypass control valve 38 is opened, the bypass 24 is released, and when the throttle opening is large and the load is high, atmospheric pressure is applied to the pressure chamber 44 and the bypass control valve 38 is closed to close the bypass 24.

In the case where the first inlet port 54 of the switching valve 50 is connected to the outlet port 52, when the throttle opening gradually increases as the load gradually increases, the bypass control valve 38 gradually closes, so that the boost pressure is It will be appreciated that it will rise slowly. However, when the throttle opening suddenly increases with a sudden increase in load, there is a response delay in the change in intake pipe pressure, and the intake pipe pressure does not immediately rise from negative pressure to atmospheric pressure. Therefore, when the switching valve 50 is in the non-energized state and the first inlet port 54 is connected to the outlet port 52, the bypass control valve 38 does not immediately close even if the load sharply increases, and the boost pressure rises. There is a delay and the required rise of torque cannot be obtained. The present invention energizes the switching valve 50 at such a time to quickly apply the atmospheric pressure of the atmospheric pressure port 58 to the pressure chamber 44, and immediately closes the bypass control valve 38 to increase the boost pressure to increase the torque. The idea is to speed up the rise. Therefore, EC
U34 is programmed to perform such control.

The ECU 34 is a conventional microcomputer and its configuration will not require explanation. The ECU 34 controls the solenoid operated directional control valve 50 by executing the control routine shown in the flowchart of FIG. 2, and thereby controls the boost pressure. EC
The U34 is mainly intended to control the fuel injection amount, the ignition timing, etc., and the supercharging pressure is also controlled by utilizing this. The supercharging pressure control routine shown in the flowchart of FIG. 2 can be executed, for example, every 16 milliseconds as an interrupt routine for the main routine.

In the flowchart of FIG. 2, an interrupt is started at step 101. Steps 102 and 103 are for determining whether the acceleration state of the vehicle is the rapid acceleration state or the gentle acceleration state.In this embodiment, the engine load is rapidly increased based on the change of the throttle opening. It is configured to determine whether there is a gradual increase or a gradual increase. That is, in step 102, the speed change ΔTA of the throttle opening TA is calculated based on the signal from the throttle sensor 36. The speed change ΔTA can be obtained, for example, by calculating the difference between the throttle opening TA at the time of the previous routine execution and the throttle opening TA at the time of the current routine execution.

Next, at step 103, it is judged if the throttle opening speed change ΔTA is larger than a set value (for example, 10 ° / 16 milliseconds). If it is large, it is considered that the engine load is in a rapid increase state, that is, the vehicle is in a rapid acceleration state, and step
Proceeding to 104, the electromagnetic switching valve 50 is energized, and in step 105, the process returns to the main routine. Thereby, the second of the switching valve 50
Since the port 56 is connected to the outlet port 52 and the atmospheric pressure of the atmospheric pressure port 58 is applied to the pressure chamber 44 of the bypass control valve 38, the control valve 38 closes the bypass 24 and the engine is supercharged.

When the throttle opening speed change ΔTA is smaller than the set value, it is considered that the load is gradually increasing, that is, the vehicle is in the slow acceleration state, and the process proceeds to step 106 to stop the energization of the switching valve 50. As a result, the first port 54 is connected to the outlet port 52, so that the control valve 38 opens and closes according to the intake pipe pressure at the signal port 62. Therefore, since the intake pipe pressure becomes negative when the load is light, the bypass control valve 38 is opened to reduce the supercharging pressure, and when the load is high, the intake pipe pressure becomes atmospheric pressure, so the control valve 38 is closed and the supercharging is performed. Is done. Further, since the intake pipe pressure gradually changes from the negative pressure to the atmospheric pressure during the gradual acceleration, the supercharging pressure gradually increases, and the engine output also relatively slowly increases.

In the above embodiment, the acceleration state is determined by utilizing the speed change of the throttle opening in the determination of step 103, but the engine is determined based on the intake air amount measured by the air flow meter 16 and the engine speed N. The intake air amount Q / N per one rotation may be calculated, and the acceleration state may be determined based on the speed change of this Q / N.

Further, a conduit 64 between the signal port 62 and the first inlet port 54 of the switching valve 50 may be provided with a throttle or a check valve with a throttle shown in Japanese Patent Application No. 60-112033. Then, the rise of the torque at the time of gentle acceleration can be moderated.

〔The invention's effect〕

The effects peculiar to the present invention can be easily understood by referring to the graph of FIG. FIG. 3 shows the characteristics of the device of the present invention and the device of the previously proposed Japanese Patent Application No. 60-112033 at the time of rapid acceleration in comparison. FIG. 3 (a) shows the change in throttle opening. , (B) shows the position of the switching valve 50, (C) shows the pressure change in the pressure chamber 44 of the bypass control valve 38, and (D) shows the torque fluctuation. When the rapid acceleration starts at time T ₁ and the throttle opening TA rapidly increases, the electromagnetic switching valve 50 is excited at time T ₂ in the device of the present invention, and the atmospheric pressure is applied from the atmospheric pressure port 58 to the pressure chamber 44. Therefore, the bypass control valve 38 is quickly closed,
The boost pressure, and thus the torque, rises quickly. On the other hand, as shown by the broken line in FIG.
In the device of No. 33, there is a delay until the pressure in the pressure chamber 44 becomes atmospheric pressure due to the response delay of the intake pipe pressure, so the bypass control valve 38 closes relatively slowly compared to the present invention.
The rise of torque also tends to be delayed.

As described above, according to the present invention, when the increase rate of the engine load is larger than the set value, the pressure chamber of the bypass control valve is released to the atmospheric pressure, so that the pressure in the pressure chamber is quickly raised to the atmospheric pressure. As a result, the supercharging pressure can be quickly increased, and thus a rapid rise of the engine output torque can be secured. Therefore, the responsiveness of the engine can be improved. In this case, since the atmospheric pressure is released into the pressure chamber, the pressure in the pressure chamber can be quickly raised to atmospheric pressure regardless of the pressure in the intake passage downstream of the throttle valve, and therefore the supercharging pressure can be raised quickly. be able to. On the other hand, when the increase rate of the engine load is smaller than the set value, the pressure chamber is kept connected to the intake passage downstream of the throttle valve. Accordingly, the bypass control valve is closed, and thus the bypass control valve can be prevented from being closed suddenly. As a result, it is possible to prevent the supercharging pressure from rising rapidly when the increase rate of the engine load is smaller than the set value, and thus to prevent the engine output torque from increasing rapidly in this case.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an engine with a supercharger equipped with the supercharging pressure control device of the present invention, FIG. 2 is a flowchart of a supercharging pressure control routine, and FIG. 3 is related to the device of the present invention and the previous proposal. It is a graph which shows the characteristic with a device. 14 ... Intake passage, 18 ... Throttle valve, 22 ... Supercharger, 24 ... Bypass, 34 ... Engine control computer, 36 ... Throttle sensor, 38 ... Bypass control valve, 44 ... Pressure chamber, 50 …… electromagnetic switching valve, 52 …… outlet port, 54, 56 …… inlet port, 58 …… atmospheric pressure port, 62 …… signal port.

Claims (1)

[Claims] 1. A turbocharger is provided in an engine intake passage downstream of a throttle valve, and the turbocharger bypasses the turbocharger to connect a discharge side and a suction side of the turbocharger with each other. A bypass control valve for controlling the amount of air flowing through the bypass control valve is connected to the intake passage downstream of the throttle valve to guide the pressure in the intake passage downstream of the throttle valve into the pressure chamber. In a supercharging pressure control device for an internal combustion engine with a supercharger, in which the opening amount of the bypass control valve increases as the pressure in the pressure chamber decreases, when the rate of increase of the engine load is smaller than a preset set value, the pressure chamber Is maintained in a state of being connected to the intake passage downstream of the throttle valve, and is provided with control means for opening the pressure chamber to the atmosphere when the increase rate of the engine load is larger than the set value.