JP2532837B2 - Idle speed control device for supercharged engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an idle speed control device for a supercharged engine equipped with a clutch means.

(Prior Art) Conventionally, for example, as seen in JP-A-60-153425, when a supercharger installed in an intake passage is driven by an output of an engine, a clutch means is installed in a drive system thereof. During idling, the clutch is disengaged to stop the drive of the supercharger, while the bypass valve provided in the bypass passage that bypasses the supercharger and throttle valve is opened to supply intake air from the bypass passage. A technique for controlling the rotation speed is known.

(Problems to be Solved by the Invention) In an engine with a supercharger as in the preceding example, controlling the idle speed by adjusting an amount of bypass air flowing through a bypass passage bypassing the throttle valve and the supercharger. In addition, a supercharging bypass passage for bypassing only the supercharger is separately provided, and the clutch means is disengaged to stop the supercharger when the engine is running at low speed and low load, and the supercharging bypass passage is opened. It is considered that natural suction is performed from the supply bypass passage to reduce the drive loss of the supercharger in the region where the required output is small.

As a result, the throttle bypass passage for controlling the idling engine speed becomes less responsive to idle control when the passage becomes longer. Further, when the supercharging pressure acts on the bypass valve interposed in the throttle bypass passage, there is a problem such as control difficulty due to an increase in the valve pressing force for preventing the opening operation due to the supercharging pressure. .

In view of the above circumstances, the present invention provides an idle speed control device for an engine with a supercharger, which ensures responsiveness of idle control and prevents supercharging pressure from acting on a throttle bypass valve. The purpose is to do.

(Means for Solving Problems) In the idle speed control device of the present invention, the upstream side is connected to an intake passage upstream of the throttle valve to bypass the throttle valve, and a throttle bypass valve is provided midway to provide idle speed control. The downstream end of the throttle bypass passage
It is characterized in that a supercharging bypass passage bypassing the supercharging device is directly connected upstream of the supercharging bypass valve.

(Operation) In the above device, when the supercharger is in a stopped state such as at low rotation and low load, intake air is supplied to the engine through the supercharging bypass passage by the opening operation of the supercharging bypass valve. Reduce the drive loss of the feeder. Further, while the throttle valve is closed at the time of idling, intake air at the time of idling is supplied from the throttle bypass passage through the supercharging bypass passage by the opened throttle bypass valve. Therefore, the throttle bypass passage for idle shares a part of the supercharging bypass passage, and the passage configuration can be simplified and shortened to ensure good responsiveness. Further, when the supercharging pressure is generated by driving the supercharger, the supercharging bypass valve in the supercharging bypass passage is closed, the supercharging pressure does not act on the throttle bypass valve, and the throttle bypass valve operates reliably. It is possible to obtain control accuracy and reliability.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram.

An intake port 4 and an exhaust port 5 are opened in a combustion chamber 3 formed above the piston 2 of the engine 1,
Both ports 4 and 5 are opened and closed by an intake valve 6 and an exhaust valve 7, respectively. In an intake passage 8 which communicates with the intake port 4 and supplies intake air to the combustion chamber 3, an air cleaner 9, an intake air amount sensor 10 for measuring the intake air flow rate, a throttle valve 11 for controlling the intake air amount, and an intake air are pressurized from an upstream side. A supercharger 12, a surge tank 13, and a fuel injection nozzle 14 for supercharging are sequentially installed.

The supercharger 12 is rotationally driven from a crankshaft 16 that rotates in association with the piston 2 by a driving force transmission system including an electromagnetic clutch 18 as a clutch means 17. That is, the transmission belt connected to the crankshaft 16 of the engine 1.
The electromagnetic clutch 18 is driven via 19, and the supercharger 12 is driven by the output shaft side of the electromagnetic clutch 18, and the connection state and disconnection by turning the control signal to the electromagnetic clutch 18 on and off. The engine driving force is transmitted and cut off corresponding to the operation of the state, and the intake supercharging by driving the supercharger 12 or the stop thereof is performed.

The upstream end is connected to the intake passage 8 between the supercharger 12 and the throttle valve 11 on the upstream side, and the downstream end is connected to the surge tank 13 downstream of the supercharger 12. A supercharging bypass passage 20 for bypassing the engine is provided. The supercharging bypass passage 20 supplies intake air when the supercharger 12 is stopped, and a supercharging bypass valve 21 for opening and closing the supercharging bypass passage 20 is provided in the middle thereof.

In the supercharging bypass valve 21, a valve body 21a that opens and closes the supercharging bypass passage 20 is supported by a diaphragm 21b, and a negative pressure chamber 21c formed at the back of the diaphragm 21b urges the valve body 21a in a valve closing direction. The spring 21d is compressed. Further, one end of a negative pressure introducing passage 22 for introducing an intake negative pressure as an opening operation source of the main body 21a is connected to the negative pressure chamber 21c, and the other end of the negative pressure introducing passage 23 is connected to the supercharging bypass valve. It is connected to the supercharging bypass passage 20 upstream of 21, and introduces an intake negative pressure acting on this portion.

A three-way solenoid valve is provided in the middle of the negative pressure introduction passage 22.
23, the three-way solenoid valve 23 is provided in the negative pressure chamber.
Negative pressure is introduced into 21c or opened to the atmosphere, and a control signal from a control unit 29 described later is output to the three-way solenoid valve 23. A check valve 24 that prevents the boost pressure from acting on the three-way solenoid valve 23 is provided in the negative pressure introduction passage 22 on the upstream side of the three-way solenoid valve 23.

Further, a throttle valve 11 installed in the intake passage 8
And a throttle bypass passage 26 for controlling the idling speed is provided. The throttle bypass passage 26 has an upstream end 26a connected to the intake passage 8 upstream of the throttle valve 11, and a downstream end 26b directly connected to a portion of the supercharging bypass passage 20 upstream of the supercharging bypass valve 21. There is.

And, in the middle of the throttle bypass passage 26,
A throttle bypass valve 27 that adjusts the amount of bypass air is provided. In the throttle bypass valve 27, the lift amount of the valve body 27a is controlled by the control unit 29 to the solenoid 27b.
The idle speed control is performed according to the bypass air amount.

Drive / stop control of the supercharger 12, open / close control of the supercharge bypass valve 21, idle speed control by the throttle bypass valve 27, and fuel injection control by the fuel injection nozzle 14,
Each is performed by a control signal from the control unit 29. The control unit 29 includes the intake air amount sensor 10 in order to detect the operating state of the engine.
In addition to the intake air amount signal from, the throttle opening signal from the throttle sensor 30 that detects the opening of the throttle valve 11,
An engine speed signal, a water temperature signal, an ignition signal, a crank angle signal, etc. are input respectively.

Then, the control unit 29 outputs an ON / OFF signal to the electromagnetic clutch 18 according to the operating state of the engine to supercharge the electromagnetic clutch 18 by disconnecting the electromagnetic clutch 18 at low engine speed and low load including at least idle time. Machine
When the drive of 12 is stopped, the ON / OFF signal is output to the three-way solenoid valve 23 in cooperation with the operation of the electromagnetic clutch 18, and when the electromagnetic clutch 18 becomes disengaged and the supercharger 12 stops. The intake negative pressure is introduced into the negative pressure chamber 21c of the supercharging bypass valve 21 to open the supercharging bypass valve 21. On the other hand, at the time of idling, a feedback signal (duty signal) is output to the throttle bypass valve 27 so that the idling speed (engine speed) becomes a predetermined speed corresponding to the water temperature and the like. Further, the fuel injection amount is obtained according to the operating state, and a fuel injection pulse is output to the fuel injection nozzle 14 at a predetermined timing to control the fuel amount (air-fuel ratio) supplied to the engine.

As described above, when the engine operating condition is in the supercharging stop region such as low rotation and low load, the control unit 29
An off signal is output from the electromagnetic clutch 18 to stop the operation of the supercharger 12, and an on signal is output to the three-way solenoid valve 23 to open the supercharge bypass valve 21. The amount of intake air at this time is adjusted by the opening degree of the throttle valve 11, and the intake air flows from the downstream side of the throttle valve 11 to the supercharging bypass passage 20, the surge tank 13, and the downstream portion of the intake passage 8, and then from the intake port 4 to combustion in an equal city. It is supplied to the chamber 3.

In the above state, when the throttle valve 11 is in the fully closed state at idle, the throttle bypass valve 27 is opened to allow the intake air for idle from the throttle bypass passage 26 to the supercharge bypass valve 21 in the open state. It is supplied through 20.

As the type of the supercharger 12, in addition to the vane type as described above, various types such as a roots type can be used.

(Effect of the Invention) According to the present invention as described above, the drive loss of the supercharger is reduced by providing it in the supercharging bypass passage that opens at least at low rotation and low load, while controlling the idling speed. By connecting the downstream end of the throttle bypass passage directly to the upstream side of the supercharging bypass valve in the supercharging bypass passage, a part of both bypass passages can be shared and the passage constitution can be simplified. The length is shortened to secure the control response of the idle speed, and when supercharging pressure is generated by the supercharger, this supercharging pressure is applied to the throttle bypass valve in the throttle bypass passage by the closed supercharging bypass valve. It is possible to prevent the operation, to ensure the reliable operation of the throttle bypass valve, and to obtain a good idle speed control.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine with a supercharger equipped with an idle speed control device according to an embodiment of the present invention. 1 ... Engine, 8 ... Intake passage 11 ... Throttle valve, 12 ... Supercharger 16 ... Crankshaft, 17 ... Clutch means 18 ... Electromagnetic clutch, 19 ... Transmission belt 20 ... Supercharging bypass Passage 21 …… Supercharging bypass valve, 22 …… Negative pressure introduction passage 23 …… Three-way solenoid valve 26 …… Throttle bypass passage 27 …… Throttle bypass valve 29 …… Control unit

Claims (1)

(57) [Claims] 1. A supercharger provided with a clutch means that is disengaged in a driving force transmission system from an engine at low speed and low load including at least idle time, and a throttle valve interposed in an intake passage upstream of the supercharger. And a supercharging bypass passage connecting an intake passage between the throttle valve and the supercharger and an intake passage downstream of the supercharger, and a supercharging operation that is opened when the clutch means is disengaged in the supercharging bypass passage. In a supercharged engine equipped with a bypass valve, the upstream end is connected to the intake passage upstream of the throttle valve to bypass the throttle valve, and the throttle bypass valve is installed midway to perform idle speed control. An idle speed control device for an engine with a supercharger, wherein a downstream end of the passage is directly connected to a supercharging bypass passage upstream of the supercharging bypass valve.