JPH02241976A - Fuel injection system of engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent adhesion of fuel to an intake passage system wall and improve starting, fuel distributing characteristics, transient characteristics, etc. by utilizing a single point injection type for a fuel injection system, and installing an air assist type injector which jets fuel and auxiliary air for atomizing simultaneously. CONSTITUTION:A single point injection SPI system is utilized for the fuel injection system of an engine 1, and an injector 5 is an air assist type which atomizes jetted fuel by jetting jetted fuel and auxiliary air for atomizing simultaneously. The air passing through an air cleaner 9 over the whole load range of the engine 1 is sucked by a vacuum pump 7, passes through an air passage 6, and is jetted to the atomizing auxiliary air supply portion 5a of the injector 5 to have a collision with jetted fuel. As a result, the jetted fuel from the injector 5 is particulated by an air assist. Since injected fuel can be atomized over the whole load range of the engine 1, it is possible to prevent fuel adhesion to the intake passage system wall.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection system for a supercharged engine.

(Prior Art and Problems to be Solved by the Invention) Generally, the fuel injection system of a supercharged engine is a capletor type or an MPI (multipoint injection) type, and there is no SP+ (single point injection) type. When adopting the SPI method, which requires fewer injectors than the MPI method, the injected fuel adheres to the walls of the intake passage system due to the distance from the fuel injection position to the combustion chamber and the large volume, resulting in poor startability, Fuel distribution characteristics, transient characteristics, etc. deteriorate. In addition, when a supercharger is installed in the intake passage, the volume of the intake passage system becomes even larger, and the above-mentioned problems such as startability, fuel distribution characteristics, transient characteristics (acceleration, response) etc. due to fuel adhesion to the walls of the intake passage system, etc. deterioration is promoted.

The present invention was made in view of the above circumstances, and prevents fuel from adhering to the walls of the intake passage system, improves startability, fuel distribution characteristics, transient characteristics (acceleration, response), etc., and improves drivability. The object of the present invention is to provide an improved fuel injection system for a supercharged engine.

(Means for Solving the Problems) In order to achieve the above object, the fuel injection system for a supercharged engine according to the first aspect of the present invention uses a single point injection system as the fuel injection system for the supercharged engine, Further, an air assist type injector is provided in the intake passage of the engine at a position immediately upstream of the supercharger, and the injector is designed to atomize the injected fuel by injecting the injected fuel and auxiliary air for atomization together. An injector injects fuel toward the rotor of the supercharger, and an air passage connects an atomization auxiliary air supply section of the injector to a position upstream of a throttle valve in the intake passage. A vacuum pump that supplies air from the upstream side of the throttle valve to the atomization auxiliary air supply section side, and a one-way valve that allows air to flow from the vacuum pump side to the injector side are installed in the air passage, respectively. It is characterized by the fact that it has been provided.

Further, in order to achieve the same object, a fuel injection system for a supercharged engine according to a second aspect of the present invention provides a supercharger that controls on/off the electromagnetic clutch of a supercharger equipped with an electromagnetic clutch according to the operating state of the engine. The fuel injection system of the charger engine is a single point injection system, and the injected fuel and auxiliary air for atomization are injected together into a position immediately upstream of the supercharger in the intake passage of the engine, thereby atomizing the injected fuel. Two air assist type injectors are provided, and an air passage connects the atomization auxiliary air supply section of these injectors to a position immediately upstream of the throttle valve in the intake passage, and the air passage is connected to the air passage. A vacuum pump that supplies air from the upstream side of the throttle valve to the atomization auxiliary air supply section side, and a one-way valve that allows air to flow from the vacuum pump side to the injector side are provided, respectively, and the electromagnetic When the clutch is on, one of the two injectors operates to inject fuel toward the rotor of the supercharger, and when the electromagnetic clutch is off, the other of the two injectors operates. The present invention is characterized in that fuel is injected toward a bypass passage that connects the upstream side and downstream side of the supercharger.

(Function) In the case of the fuel injection system for a supercharged engine according to the first claim, when the engine is fully loaded, the air upstream of the throttle valve is sucked by the vacuum pump and is used to atomize the injector through the air passage. The fuel is injected into the auxiliary air supply section, and the injected fuel is atomized by so-called air assist. Furthermore, since the injector injects the fuel toward the rotor of the supercharger and collides with the rotor, atomization of the injected fuel is promoted.

Further, in the case of the fuel injection system for a supercharged engine according to the second claim, when the engine is under medium or high load, that is, when the electromagnetic clutch of the supercharger is on, one of the injectors operates to inject the supercharger. At the same time, the air upstream of the throttle valve is injected into the atomization auxiliary air supply section of one of the injectors via the air passage and collides with the injected fuel. Since the fuel is atomized, the fuel does not adhere to the walls of the intake passage system. Further, since fuel is injected by one of the injectors toward the rotor of the supercharger and collides with the rotor, atomization of the injected fuel is promoted.

Furthermore, when the engine load is low, that is, when the electromagnetic clutch of the supercharger is off, the other injector operates and injects fuel toward the bypass passage of the supercharger, and the other injector atomizes the fuel. The air upstream of the throttle valve is ejected into the auxiliary air supply section and collides with the injected fuel,
Since the fuel is atomized by so-called air assist, the fuel does not adhere to the walls of the intake passage system. Further, when the electromagnetic clutch is off, fuel is not injected toward the rotor of the supercharger, so fuel does not accumulate near the supercharger. Therefore,
Overrichness immediately after the electromagnetic franc is turned on or off, deterioration of fuel distribution characteristics, cycle-by-cycle A/F (air-fuel ratio) fluctuations, deterioration of transient characteristics, etc. are eliminated.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a configuration diagram of a fuel injection system for a supercharged engine showing an embodiment of the present invention. In the figure, 1 is an engine, and its fuel injection system is a 5PI (single point injection) system. has been done. A throttle valve 3 is provided in the middle of an intake passage 2 of this engine 1. A supercharger 4, which is a Roots-type supercharger, is provided in the intake passage 2 between the throttle valve 3 and the engine 1 and is mechanically driven by the engine 1. Located right upstream of this supercharger 4, in the intake passage 2,
An injector 5 is provided that injects fuel toward a rotor (not shown) of the supercharger 4.

This injector 5 is of an air assist type that aims at atomizing the injected fuel by injecting the injected fuel and the auxiliary air for atomization together.

FIG. 2 shows an example of an air assist type injector 5, in which a bottle-type valve body 50 has a plurality of air introduction holes 5.
1a is attached, and a mixing chamber 51c is formed around the bottle portion 50a at the tip of the needle. A nozzle surface 51b is formed on the tip end surface of the adapter 51. The mixing chamber 51c opens therein and the nozzle surface 51b expands in the fuel injection direction. The above-mentioned adapter 51
The air introduction hole 51a, the mixing chamber 51c, the nozzle surface 51b, etc. form an auxiliary air supply section 5a for atomization.

Auxiliary air for atomization introduced into the mixing chamber 51c through an air introduction hole 51a from the air passage 6, which will be described later, mixes with the injected fuel from the valve body 50, and jets them out together from the mixing nozzle surface 51b. As a result, the injected fuel that leaves the bottle portion 50a at the tip of the needle is atomized by the shearing action of the air flow.

The atomization auxiliary air supply section 5a of the injector 5 and the upstream portion of the throttle valve 3 are connected through an air passage 6. A vacuum pump 7 and a one-way valve 8 are provided in the middle of the air passage 6, respectively. This vacuum pump 7 supplies air from the upstream side of the throttle valve 3 to the atomization auxiliary air supply section 5a side, and the one-way valve 8 supplies air from the vacuum pump 7 side to the injector 5a side.
Allow flow to the side. An air cleaner 9 is installed in the intake passage 2 located upstream of the throttle valve 3 in the air passage 6.
is the provision.

In the full load range of the engine 1, the air that has passed through the air cleaner 9 is sucked by the vacuum pump 7, passes through the air passage 6, and is injected into the atomization auxiliary air supply section 5a of the injector 5, forming injected fuel. collide. As a result, the fuel injected from the injector 5 is atomized by so-called air assist.

In this way, since the injected fuel can be atomized in the entire load range of the engine 1, it is possible to prevent the fuel from adhering to the walls of the intake passage system.

Next, a second embodiment of the present invention will be described based on FIGS. 3 and 4. In this embodiment, the same parts as those in the embodiment shown in FIGS. 1 and 2 described above will be described with the same reference numerals in the drawings. This second embodiment has two air assist type injectors 5A, a supercharger 4a equipped with an S/C electromagnetic clutch (not shown) that is controlled on/off depending on the operating state of the engine 5B, a bypass passage 10 connecting the upstream and downstream parts of the supercharger 4a, and a bypass valve 11 in this bypass passage 10.
This embodiment differs from the embodiment shown in FIG. 1 in that the embodiment shown in FIG. still,
Injectors 5A and 5B are injectors 5 shown in FIG.
The bypass valve 11 is a negative pressure responsive type that opens and closes in response to the intake negative pressure generated downstream of the throttle valve 3, and opens in engine operating ranges B and C shown in FIG. In addition, in the medium/high load region (Ag region in Fig. 5) where the throttle valve 3 is wide open, the bypass valve 1 is closed.
1 is closed. In the engine operating ranges A and B described above, the S/C electromagnetic clutch is turned on to drive the supercharger 4a, and in the engine operating range C, it is turned off.

Then, at medium/high load of engine 1, that is, supercharging a4a
When the S/C electromagnetic clutch is on (engine operating range (A+B) shown in Fig. 6, these ranges A and B correspond to operating ranges A and 2 in Fig. 5), one injector 5A operates, and fuel is injected toward the rotor (not shown) of the supercharger 4a.

Further, when the engine 1 is under low load, that is, when the electromagnetic clutch of the supercharger 4a is off (engine operating region C shown in FIG. 6), the other injector 5B operates to direct fuel toward the bypass passage IO. is injected. The other functions of this second embodiment are the same as those of the embodiment shown in FIG. 1, so their explanation will be omitted.

(Effects of the Invention) As described above, the fuel injection system for a supercharged engine according to claim 1 of the present invention is such that the fuel injection system of the supercharged engine is a single point injection system, and the fuel injection system of the supercharged engine is a single point injection system, and An air assist type injector is installed immediately upstream of the machine to atomize the injected fuel by injecting the injected fuel and auxiliary air for atomization together. The auxiliary air supply section for atomization of the injector and the position immediately upstream of the throttle valve in the intake passage are connected through an air passage, and the air passage for atomization is injected from the upstream side of the throttle valve into this air passage. The present invention is characterized in that it is provided with a vacuum pump that supplies air to the auxiliary air supply section and a one-way valve that allows air to flow from the vacuum pump side to the injector side.

Therefore, in the entire load range of the engine, the injected fuel can be atomized by air assist, preventing fuel from adhering to the walls of the intake passage system, improving startability, fuel distribution characteristics, and transient characteristics (
This results in improved acceleration, responsiveness, etc., and improved drivability.

Further, the fuel injection system for a supercharged engine according to claim 2 of the present invention is a fuel injection system for a supercharged engine that controls on/off an electromagnetic clutch of a supercharger with an electromagnetic clutch according to the operating state of the engine. This is an air assist type that uses a single point injection method, and aims to atomize the injected fuel by injecting the injected fuel and auxiliary air for atomization together at the position immediately upstream of the supercharger in the engine intake passage. Two injectors are provided, and an air passage communicates between the atomization auxiliary air supply section of these injectors and a position immediately upstream of the throttle valve in the intake passage, and the atomization auxiliary air supply part of these injectors is connected from the upstream side of the throttle valve to the air passage. A vacuum pump that supplies air to the air supply section and a one-way valve that allows air to flow from the vacuum pump side to the injector side are provided, and when the electromagnetic flange is on, one of the two injectors operates and injects fuel towards the rotor of the supercharger, and when the electromagnetic clutch is off, the other of the two injectors operates and connects the upstream and downstream sides of the supercharger. This is characterized in that fuel is injected toward the bypass passage.

Therefore, the same effects as in claim 1 described above are achieved. Further, when the electromagnetic clutch is off, fuel is not injected toward the rotor of the supercharger, so fuel does not accumulate near the supercharger. Therefore, overrichness immediately after the electromagnetic clutch is turned on or off, deterioration of fuel distribution characteristics, and A
/F (air-fuel ratio) fluctuations, deterioration of transient characteristics, etc. are eliminated.

Furthermore, it is possible to cool the intake air during fuel vaporization without using an interthaler, and unlike the MP1 system, fuel is supplied using fewer fuel injection valves, which reduces the number of parts and lowers the product price. It can be reduced to a large extent.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a fuel injection system for a supercharged engine showing an embodiment of the present invention, FIG. First example
Figure 4 is an enlarged sectional view of the injector part in Figure 3, Figure 5 is the bypass valve 11 and supercharging a4 in Figure 3.
A graph showing the operating range of FIG. 6 is for the injector 5A of FIG. 4. 5B is a graph showing the operating range of 5B. 1...Engine, 2...Intake path Fa, 3...Thrower) Jl/valve, 4,4a...Supercharger, 5.5A,
5B... Injector, 5a... Auxiliary air supply section for atomization, 6... Air passage, 7... Vacuum pump, 8... Unidirectional applicant Mitsubishi Motors Corporation

Claims (2)

[Claims] (1) By making the fuel injection system of the supercharged engine a single point injection system, and injecting the injected fuel and the atomization auxiliary air together into a position immediately upstream of the supercharger in the intake passage of the engine. An air assist type injector is provided to atomize the injected fuel, the injector injects fuel toward the rotor of the supercharger, and an auxiliary air supply section for atomization of the injector is provided. a vacuum pump that communicates between the intake passage and a position immediately upstream of the throttle valve through an air passage, and supplies air to the air passage from the upstream side of the throttle valve to the side of the auxiliary air supply unit for atomization; A fuel injection system for a supercharged engine, characterized in that the fuel injection system is provided with a one-way valve that allows air to flow from the pump side to the injector side. (2) The fuel injection system of the supercharger engine that controls on/off the electromagnetic clutch of the supercharger with an electromagnetic clutch according to the operating state of the engine is a single point injection system, and the supercharging in the intake passage of the engine is provided. Two air assist type injectors are installed immediately upstream of the machine to atomize the injected fuel by injecting the injected fuel and auxiliary air for atomization together, and the auxiliary air for atomization is supplied to these injectors. and a position immediately upstream of the throttle valve in the intake passage through an air passage, and a vacuum pump configured to supply air from the upstream side of the throttle valve to the atomization auxiliary air supply unit side through the air passage; a one-way valve that allows air to flow from the vacuum pump side to the injector side, and when the electromagnetic clutch is on, one of the two injectors operates to direct air toward the rotor of the supercharger. and when the electromagnetic clutch is off, the other of the two injectors operates to inject fuel toward a bypass passage that communicates between an upstream side and a downstream side of the supercharger. A fuel injection system for a supercharged engine.