JPS6187920A - Engine with supercharger - Google Patents

Abstract

PURPOSE:To have high-precision sensing of the amount of suction gas, in an arrangement wherein a relief control valve is furnished to relieve the supercharge gas, by installing a motion suppressing means to allow the relief valve to open or close slowly CONSTITUTION:A supercharger 17, intercooler 18 and surge tank 19 driven by the engine concerned are provided on the supercharge passage 13 divergent from the main suction passage 12. It shall diverge into to branches; a secondary air passage 21 to send part of the supercharge gas from said surge tank 13 on the supercharge passage 13 to the exhaust system to serve as secondary air for purification of the exhaust gas, and a relief passage 22 to relieve excessive supercharge gas. This relief passage 22 is provided with a supercharge pressure control valve 26 and a relief control valve 27. Here the relief control valve 27 is put in operation by a neg. pressure actuator 27b, and the suction neg. pressure or the atmosphere is introduced into its diaphragm chamber through a delay valve 35 and a three-way solenoid valve 34 as motion suppressing means.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention defines one suction passage and a supercharging passage, and
A detection device for the air ω sent to these passages is used for the supercharging (1a) engine.

(Prior Art) Engines have conventionally been known in which, in addition to the main intake passage, a supercharging passage with one large supercharger driven by the engine is installed to improve the engine output. . In the case of using an electronic fuel injection device that controls the fuel injection amount according to the intake air amount in the engine of this scale, as shown in Japanese Patent Publication No. 5781,
The supercharging passage is branched from the main intake passage, and an air amount detection device is installed upstream of -ε.
It is designed to detect the amount of intake air from the engine. In such a supercharged engine 43, a relief passage for relieving excess supercharging air is connected to the supercharging passage. Generally, the following relief passage is often provided with a relief control valve that opens and closes the relief passage depending on the operating state. However, in the engine shown in the above-mentioned publication, in which the secondary air passage is branched from the supercharging passage in order to utilize a portion of the supercharging air to the secondary air, -. In general, the structure is such that the secondary air passage is opened and closed in a 1.7J pattern depending on the operating condition that requires secondary air and the operating condition that requires outlet. In order to prevent excessive secondary air from being sent to the exhaust system when the secondary air passage is open, a relief control valve opens and closes the relief passage according to the operating conditions in response to the opening and closing of the secondary air passage. is provided.

In this structure, when the above-mentioned relief control valve suddenly closes when the operating condition changes, the closing operation will be temporarily suppressed due to the detection of excess air that is suddenly forced into the supercharging passage and not supplied to the combustion chamber. Detection errors occur and the air-fuel ratio becomes rich, and also when the relief control valve is opened, air is suddenly released from the supercharging passage to the relief passage, causing detection errors and the air-fuel ratio becoming lean.

In addition, in the engine disclosed in the above publication, the total intake air amount is detected by the first air amount detection device provided upstream of the branch point between the main intake passage and the supercharging passage, and the supercharging air is sent to the first air slide. A second air amount detection device detects the flow rate of the air sent to the relief passage and the secondary air passage, which are recirculated upstream of the detection device, and the second air V is detected from the output of the first air amount detection device. The interval between the intake air supply to the combustion chamber is detected by subtracting the output of the detection device, but in this case as well, if the relief control valve is suddenly opened or closed, the interval between the intake air supply to the combustion chamber is detected. An error will occur.

Furthermore, in the above explanation, an engine having a secondary air passage branched from the supercharging passage was used as an example, but even if the engine does not have such a secondary air passage, a relief control valve that opens and closes the relief passage can be used. When the relief control valve is suddenly opened and closed in the engine equipped with the engine, an error occurs in the detected value at the intake end as described above.

(Object of the Invention) In view of these circumstances, the present invention provides a leaf passage for relieving the pressurized air in the supercharging passage, and a relief control valve that opens the relief passage according to the operating condition. Another object of the present invention is to enable highly accurate detection of the intake air supply to the combustion chamber even when the relief control valve is opened and closed.

(Structure of the Invention) In addition to the main intake passage, the present invention branches a supercharging passage that supplies pressurized air from the supercharger from the main intake passage, and provides an air amount detection device upstream of this branch. On the other hand, a relief passage is provided to relieve the pressurized air in the supercharging passage, and a relief control valve is installed to open and close this relief passage depending on the operating condition of the engine.
An operation suppressing means is provided to gradually open and close the relief control valve when the relief control valve is opened and closed. In other words, when the relief control valve opens and closes, it is designed to prevent sudden fluctuations in the pressure in the relief air (6) and the supercharging passage. Detection accuracy between intake air supply is improved.

(Embodiment) Fig. 1 shows an embodiment of the device of the present invention, in which 1 is a cylinder of an engine, 2 is a piston, and 3 is a combustion chamber formed above the piston 2 in the cylinder 1. .

A main intake boat 4, a supercharging boat 5, and an exhaust boat 6 are located in front of this combustion chamber 3, and a main intake valve 7, a supercharging intake valve 8, and an exhaust valve 9 are installed in these boats 4.5.6. ing.

10 is an air cleaner, and 11 is an intake passage connected to the air cleaner 10. The intake passage 11 is the main intake passage 12
and a supercharging passage 13 branched from this main intake passage 12, the downstream end of the main intake passage 12 is connected to the main intake boat 4, and the downstream end of the supercharging passage 14 is connected to the supercharging boat 5. has been done.

An air flow meter 14 as an air amount detection device is provided in the intake passage 11 upstream of the branch point between the main intake passage 12 and the supercharging passage 13. Also, the main intake passage 12
Inside, there is a first valve that opens and closes in response to the operation of the accelerator pedal.
A throttle valve 15 is provided, and a fuel injection device 16 is provided downstream thereof.

On the other hand, the supercharging passage 13 is provided with a supercharging member 17 consisting of a vane type air pump driven by the engine. An intercooler 18 is provided downstream of the supercharger 17 to cool the supercharged air supplied from the supercharger 17 in order to increase its density, and a surge tank 19 is formed in the flow of the intercooler 18. .

Furthermore, a second
A throttle valve 20 is provided, and when the load exceeds a predetermined load, the second throttle valve 20 is opened to an opening degree corresponding to the load. For example, when the first throttle valve 15 is opened to a predetermined opening degree or more, They are designed to be opened in conjunction with each other.

From the surge tank 19 of the supercharging passage 13, there is a secondary air passage 21 that sends a part of the supercharging air to the exhaust system as secondary air for exhaust gas purification, and a secondary air passage 21 that releases excess supercharging air. The secondary air passage 21 is connected to the exhaust passage 60 communicating with the exhaust port 6, and the relief passage 22G, L is connected to the main intake passage 12 downstream from the air 70-meter 14. There is.

The secondary air passage 21 shown in F has a secondary air flow rate which is configured to detect the flow rate of the secondary air using, for example, a differential pressure sensor 23b that detects the pressure difference between the upstream side and the downstream side of the throttle 23a. A detector 23, a secondary air control valve 24 that opens and closes the secondary air passage 21 depending on the operating state downstream of the detector 23, and a check valve 25 are provided. The secondary air control valve 24 is composed of a valve body 24a provided in the secondary air passage 21 and a diaphragm type actuator 24b.

In addition, the relief passage 22 includes a 1iJ filtration supply pressure control valve 26 that mainly controls the maximum boost pressure at high loads, and a leaf control valve 27 that opens and closes according to the operating state ffA so as to open when secondary air is supplied. are arranged side by side. In the figure, the opening 28. of the relief passage 22 is located at 21a of the surge tank 19. '2
9, one opening 28 is opened and closed by the boost pressure control valve 26, and the communication hole 30 between the other opening 29 and the relief passage 22 is opened and closed by the relief control valve 27.
It is opened and closed by

The supercharging pressure control valve 26 includes a valve body 26a disposed in one opening 28, a diaphragm 26b connected to the valve body 26a, and a pressure control chamber 2 formed on one side of the valve body 26a.
6G and the valve body 26a installed in this chamber 26c.
and a spring 26d that biases the valve in the valve closing direction, and when the supercharging pressure applied to the valve body 26a becomes excessively m<, the valve body 26a releases the supercharging air in the surge tank 19. , thus controlling the maximum boost pressure. The pressure ajl + chamber 26G is connected to the first
Intake negative pressure is introduced from the main intake passage 12 downstream of the throttle valve 15, so the maximum boost pressure is lowered at low loads where the intake negative pressure is large, and the maximum boost pressure is increased to some extent at high loads where the intake negative pressure is small. I'm trying to be able to do that. Also,
The relief control valve 27 includes a valve body 27a disposed in the communication hole 30 and a die 17' noram type actuator 2.
7b.

Each actuator 24b, 27b of the secondary air control valve 24 and the relief control valve 27 is connected to the negative pressure passage 31 via a passage 32, 33 and a three-way solenoid valve 34. When the three-way 1if4i valve 34 is turned ON, intake negative pressure is introduced into each of the actuators 24b and 27b, and the secondary air control valve 24 and the relief control valve 27
When the three-way solenoid valve 34 is turned off, the atmosphere is introduced into each of the actuators 24b and 27b, and the secondary air control valve 24 and the relief control valve 27 are closed.

A delay valve 35 is provided in the passage 33 between the actuator 27b of the relief control valve 27 and the three-way solenoid valve 34 as an operation suppressing means for gradually performing the nrn operation of the relief & II control valve 27. This delay valve 35 is configured to restrict the flow of air within the passage 33 by means of a throttle 36.

Further, 37 is a control unit using a microcomputer, and each detection signal from the air 70-meter 14J5 and the secondary air detection value 23 is input to this control unit 37, and the engine rotation speed is inputted to this control unit 37. Detection signals from a rotational speed sensor 38 and a throttle opening sensor 39 that detects the load by detecting the opening of the first throttle valve 15 are also input. The control unit 37 controls the air 70
- The intake air supply amount to the combustion chamber 3 is detected based on the output of the meter 14 and the differential pressure sensor 23b, and the fuel injection amount from the fuel injection device 16 is controlled according to this intake air supply amount, while the engine rotation speed is The three-way solenoid valve 34 is controlled to be turned on in the operating range where the load is below a predetermined value, and the three-way solenoid valve 34 is turned off in other operating ranges.

In this supercharged engine, when the engine is operating at relatively low rotation speed and low load, the secondary air control valve 24 is opened, so that part of the supercharged air is transferred to the secondary air. and is sent to the exhaust passage 60, and the relief f1.
By opening the lJ control valve 27, the supercharged air is also released to the relief passage 22, and the pressure inside the surge tank 19 is kept as low as possible, preventing excess secondary air. be done. At this point, the relieved air is recirculated downstream from the air flow meter 14.
Therefore, the value obtained by subtracting the secondary air supply crucible from the air m measured by the air flow meter 14 becomes the intake air supply amount to the combustion chamber 3, and the fuel injection from the fuel injection device 16 ([ In addition, when the engine speed or load is in an operating range higher than a predetermined value, the secondary air control valve 24 is closed to stop the supply of secondary air, and the relief valve 24 is closed. The control valve 27 is in an open state. In this state, supercharging air is relieved only when the supercharging pressure control valve 26 is activated due to an increase in supercharging pressure, and when the relief control valve 27 is open. The supercharging pressure is increased, and the supercharging effect on the combustion chamber 3 is enhanced.When the supply of secondary air is stopped, the air detected by the air flow meter 14 flows into the combustion chamber 3. This is the amount of intake air supplied to the engine, and fuel injection is controlled accordingly.

When the secondary air control valve 24 and the relief control valve 27 are switched from an open state to a closed state in response to a change in the operating state, the three-way solenoid valve 34 is turned OFF and the multi-valve 24 is switched off.
, 27 actuators 24b and 27b, and when the multiple valves 24 and 27 are switched from the closed state to the open state, the three-way solenoid valve 34 is turned on and the actuators 24b and 27b are turned on. Negative pressure is introduced into the

During this switching, pressure or negative pressure is gradually introduced into the actuator 27b of the relief control valve 27 via the delay valve 35, so that the relief control valve 27
7 is gradually opened or 111 is operated. As a result, the accuracy of detecting the amount of intake air supplied to combustion ¥3 is increased.

In other words, if the relief control valve 27 is suddenly closed just as it is being switched from the open state to the closed state, the air flow meter 14 will detect this as the supercharging air relief is stopped. The amount of air increases rapidly, and the increased amount is stored in the surge tank 19 and is not supplied to the combustion chamber 3.
The detected value of the intake air supply amount based on the output of the air 70-meter 14 becomes larger than the true intake air supply amount. Since the fuel injection amount is controlled based on the detected value of the intake air supply amount, the fuel becomes richer than the appropriate value. Also, relief control valve 2
If the same operation is performed suddenly when the valve 7 is switched from the closed state to the open state, the air that has already accumulated in the surge tank 19 will flow from the relief passage 22 to the air 70-meter 1.
4, the airflow meter 14
The amount of air detected at the engine rapidly decreases, the detected value of the intake air supply amount becomes less than the true intake air supply amount, and therefore the fuel becomes leaner than the proper value.

On the other hand, if the relief control valve 27 is gradually opened or closed as described above, even during such a transient situation,
The difference between the detected value of the intake air supply amount and the true intake air supply amount becomes smaller, and fuel control is performed appropriately.

In the above example, the delay valve 35 is used as an operation suppressing means for gradually opening and closing the relief control valve 27, but it is also possible to gradually open and close the relief control valve 27 using an electric actuator. good.

The relief passage 22 also provides relief air for supercharging Ia17.
It may be made to flow back to the upstream supercharging passage 13. Alternatively, a relief passage may be formed so that the relief air is recirculated upstream from the air flow meter 14. In this case, a means for detecting the amount of relief air is provided, and the air amount detected by the air flow meter 14 is detected by the relief passage. The intake air supply 51 to the combustion chamber 3 may be determined by reducing the relief air amount J3 and the secondary air amount. In this case as well, when the relief control valve 27 is suddenly opened/closed, the amount of relief air subtracted from the air m detected by the air flow meter 14 changes, causing the actual intake air to enter the combustion chamber 3. Since there is a difference between the supply 〇 and the intake air supply suspension detection, it is effective to gradually open and close the relief control valve 27.

(Effects of the Invention) As described above, the present invention allows the relief control valve to be opened and closed gradually when the relief passage for relieving supercharged air is opened and closed depending on the operating state by the relief control valve. Therefore, even when the relief control valve is opened and closed, large errors are prevented from occurring in the detection In of the intake air supply amount to the combustion chamber, which is determined based on the output of the air amount detection means, and the appropriate fuel It is , II control.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an embodiment of the invention. 12... Main intake passage, 13... Supercharging passage, 14...
- Air 70-meter (air is the detection means), 17...Supercharger, 22...Relief passage, 27...Relief control valve, 35...Delay valve (lower stage of l-motion suppression).

Claims (1)

[Claims] 1. In addition to the main intake passage, a supercharging passage that supplies pressurized air from the turbocharger is branched from the main intake passage, and an air amount detection device is installed upstream of this branch, while In addition to providing a relief passage to relieve pressurized air,
The engine is provided with a relief control valve that opens and closes the relief passage depending on the operating state of the engine, characterized in that an operation suppressing means is provided that gradually opens and closes the relief control valve when the relief control valve is opened and closed. A supercharged engine.