JPS595782B2 - Fuel control device for supercharged engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a supercharger driven by an engine.
The present invention relates to fuel control for a supercharged engine in which pressurized air or an air-fuel mixture is supplied to a combustion chamber of the engine in addition to intake air taken in by negative intake pressure.

Conventionally, the technical idea of increasing charging efficiency and improving engine output by supplementally supplying pressurized air or air-fuel mixture in addition to naturally-intake air as described above has been known. .

In this type of supercharged engine, when adopting an electronically controlled fuel injection device that sets the fuel injection amount according to the amount of intake air, pressurized air or air-fuel mixture (hereinafter referred to as It is simply called supercharging air.

) is also important for setting the fuel injection amount, and in order to detect the amount of supercharging air, it is advantageous to install an air amount detection device such as an air flow meter in the supercharging passage in addition to the intake passage. be.

However, this type of supercharging is not always carried out over the entire engine load range, and moreover, at low engine loads, the exhaust gas purification system does not have enough supercharging.
It is necessary to supply secondary air to the exhaust system, and in engines equipped with a supercharger, it is advantageous to supply a portion of the supercharged air discharged by the supercharger to the exhaust system as secondary air. .

Therefore, depending on the engine operating conditions, the entire amount of air detected by the air amount detection device installed in the supercharging passage may not be supplied to the combustion chamber of the engine. If the fuel injection amount is set according to the air amount, there is a problem that fuel becomes excessive.

The present invention has been made in view of such problems, and includes:
A first air amount detection device is provided to detect the amount of intake air actually taken into the combustion chamber from the main intake port through the main intake passage. A second air amount detection device is provided to detect the amount of supercharged air actually supplied to the combustion chamber, and an electronically controlled fuel injection device is connected to the first. It is an object of the present invention to provide a fuel control device for a supercharged engine that can perform control based on the sum of the forces of a second air amount detection device, and thus can always accurately set the fuel injection amount.

Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments.

In the figure, E is a reciprocating engine that rotates a crankshaft 2 by the reciprocating motion of a piston 1, 3 is a main intake port opened to a combustion chamber 5 during the intake stroke by a main intake valve 4, and 6 is a supercharging valve. 7 is a supercharging port opened to the combustion chamber 5 at the end of the intake stroke, and 8 is an exhaust port opened by an exhaust valve 9 during the exhaust stroke.

Further, 10 is an air cleaner, 11 is a main intake passage connected to the air cleaner 10, 12 is a first air amount detection device including an air flow meter or the like that detects the amount of air passing through the main intake passage 11, and 13 is the main intake passage 11. is a supercharging passage independently connected to the air cleaner 10.

A main intake passage 11 communicating with the main intake port 3 has a throttle valve 1 which is opened and closed according to the load of the engine E.
4, a fuel injection device 15 controlled by computer A is installed downstream thereof.

On the other hand, a supercharger 16 consisting of a vane type air pump driven by the engine E is provided upstream of the supercharging passage 13 communicating with the supercharging port 6, and a supercharger 16 consisting of a vane type air pump driven by the engine E is provided downstream of the supercharger 16. A secondary air passage 17 for supplying secondary air is provided in a branched manner, and further downstream from which branch point of the secondary air passage 17, a supercharging port 6 is actually supplied into the combustion chamber 5. Second air amount detection device 1 consisting of an air flow meter, etc. for detecting the amount of air
There are 8.

Note that the engine E is downstream of the second air amount detection device 18.
A flow control valve 19 is provided which is opened and closed according to the load of the engine E, and the amount of supercharging is adjusted according to the load of the engine E.

In addition, in the middle of the secondary air passage 17, a portion of the air that is divided into the secondary air passage 17 is transferred to the engine E according to the load of the engine E.
The secondary air is supplied to the upstream of the exhaust gas purification device 22 in the exhaust passage 21 of the IJ IJ-), while the remainder is supplied to the supercharging passage 13 upstream of the supercharger 16 via the relief passage 24.
A flow rate adjustment valve 25 for secondary air control is provided.

A relief passage 27 provided with a check ball type relief valve 26 is connected to the secondary air passage 17 before the flow rate adjustment valve 25, and the other end of the relief passage 27 is connected to the IJ I
It communicates with the downstream side of the J-F passage 24, and provides relief through this relief passage 27 when the pressure in the secondary air passage 17 becomes high.

In addition, a large number of water cooling fins 24a and 27a are provided in the middle of the relief passage 24 and the relief passage 27,
A water cooling device 28 is provided that surrounds these fin portions 24a and 27a and circulates cooling water inside, and the air adiabatically compressed by the supercharger 17 is supplied to the IJI.
It is cooled during the J-F process and is returned to the suction side of the supercharger 17 as high-density air, thereby preventing a decrease in the density of the supercharging air as much as possible.

Next, the operation of the above configuration will be explained.

Now, assuming that the engine E is being operated under a certain load condition, the throttle valve 14 of the main intake passage 11 and the supercharging amount control valve 19 of the supercharging passage 13 are operated as follows.
The opening force is set according to the load, and the supercharging air supplied by the supercharger 16 enters the combustion chamber 5 according to the opening of the supercharging amount control valve 19. At the end of the intake stroke, the supercharging valve 7 is opened. It is supercharged when the power is turned off.

In addition, a part of the supercharging air supplied by the supercharger 16 is
Mainly, the flow is divided into the secondary air passage 1T according to the set opening degree of the flow rate adjustment valve 25, and the secondary air passage 17 is also supplied to the exhaust gas passage 21, and the surplus is sent to the supercharger via the IJ-F passage 24. 16, it is cooled by a cooling device 28 and then relieved.

The amount of fresh air taken into the main intake port 3 or the combustion chamber 5 through the main intake passage 11 is detected by the first air amount detection device 12 provided in the main intake passage 11, and The amount of supercharging air supplied to the combustion chamber 5 through the supercharging port 6 is detected by a second air amount detection device 18 provided downstream from the branching point with the secondary air passage 17.

These first. The detection output of the second air amount detection device 12.18 is input to the computer A that controls the fuel injection device 15, and the computer A sets the fuel injection amount required at that time from the sum of both outputs. Fuel injection device 1
5 injects fuel corresponding to the total amount of air supplied to the combustion chamber 5 into the main intake passage 15 to ensure an accurate air-fuel ratio.

In addition, in the above embodiment, the main intake passage 11 and the supercharging passage 13
Although the supercharging passages are provided independently, the present invention can also be applied to a configuration in which the supercharging passage is branched from the upstream side of the main intake passage 11.

In this case, the first air amount detection device may be installed downstream of the branch point of the main intake passage with the supercharging passage.

As is clear from the above detailed explanation, the present invention provides a first air amount detection device in the main intake passage for detecting the amount of intake air actually taken into the combustion chamber from the main intake port, and In the supercharging passage that supplies supercharging air by the charger, downstream from the branching point with the secondary air passage, there is a second air quantity that detects the amount of supercharging air that is actually supplied to the combustion chamber from the supercharging port. A detection device is provided, and an electronically controlled fuel injection device provided in the main intake passage is connected to the first. The present invention provides a fuel control device for a supercharged engine, characterized in that control is performed by the sum of both outputs of a second air amount detection device.

According to the present invention, since the total amount of air supplied to the combustion chamber can always be detected correctly, the fuel injection amount can be accurately controlled, and the advantage is that stable air-fuel ratio control can be achieved.

[Brief explanation of the drawing]

The drawing is an overall schematic explanatory diagram of an engine showing an embodiment of a fuel control device for a supercharged engine according to the present invention. E...Engine, 3...Main intake port, 6...Supercharging port, 11...Main intake passage, 12......No. 1 Air amount detection device, 13...
...Supercharging passage, 16...Supercharger, 17...
...Secondary air passage, 18...Second air amount detection device.

Claims (1)

[Scope of Claims] 1. A supercharging passage that supplies pressurized air from a supercharger is provided in addition to the main intake passage, and a secondary air passage is branched from the supercharging passage to be connected to the exhaust system. In a supercharged engine, an electronically controlled fuel injection device is installed in the main intake passage, a first air amount detection device for measuring the amount of intake air is installed upstream of the main intake passage, and a secondary air injector is installed in the supercharging passage. A second air amount detection device for measuring the amount of supercharged air is provided downstream from the branching point with the passage, and an output obtained by adding the output of the first air amount detection device and the output of the second air amount detection device is used to A fuel control device for a supercharged engine, characterized in that the fuel injection amount of a control fuel injection device is controlled.