JPS58110855A - Fuel controlling apparatus for engine - Google Patents

Abstract

PURPOSE:To control the amount of fuel to be injected to a main intake system and an auxiliary intake system appropriately, by providing a fuel injection nozzle in each of the main intake system and the auxkliary intake system of an engine of the type in which supercharging air is supplied from an auxiliary intake passage when the engine load is high, so that fuel is supplied to these nozzles from a single fuel pump. CONSTITUTION:A main intake passage 11 and an auxiliary intake passage 12 branched from an intake passage concentrated section 13 are connected respectively to a main intake port 4 and an auxiliary intake port 6 which are opened in a combustion chamber 3, and a throttle valve 14 is provided in the main intake passage 12. On the other hand, a supercharger 15 is provided in the auxiliary intake passage 12, and a supercharging valve 16 that is opened when the engine load is higher than a predetermined level is also provided in the auxiliary intake passage 12. Here, the intake passages 11, 12 have respective fuel injection nozzles 21, 22, to which fuel is supplied from a common fuel supply pump 25 via branch passages 31, 32. Further, fuel relief passages 34, 35 are connected respectively to the nozzles 21, 22, and fuel pressure control valves 36, 37 operated in response to the intake pressure and the fuel pressure are provided respectively in the fuel relief passages 34, 35.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel control device for a partial supercharging engine that performs supercharging from an auxiliary intake passage during high loads.

Conventionally, in order to improve output during high loads in automobile engines, a main intake system and an auxiliary intake system were installed together.
A partial supercharging system in which the auxiliary intake system is equipped with a supercharger, and at least during the compression stroke, supercharged air is supplied from the auxiliary intake system in addition to fresh air from the main intake system when the engine load exceeds the set load. The engine is known. Most conventional engines of this type have a fuel system installed only in the main intake system, because the auxiliary intake system equipped with a supercharger is under positive pressure, making it difficult to install a fuel system. Only air was supplied from the intake system. However, in this case, since a temperature increase occurs in the auxiliary intake system due to frictional heat of the supercharger and adiabatic compression, the intake air temperature becomes abnormally high, which may cause abnormal combustion such as knocking.

As a countermeasure to such problems, the already filed patent application No. 1
No. 17971 discloses a system in which a fuel injection nozzle is also provided in the auxiliary intake system, and the intake air temperature is lowered by the latent heat of vaporization of the fuel injected from the fuel injection nozzle during supercharging. However, in this structure, fuel is simply distributed and supplied from the fuel supply pump to each fuel injection nozzle in the main intake system and the auxiliary intake system, so it is difficult to properly inject fuel, especially in the auxiliary intake system. The problem was that it was difficult to control the amount. In other words, the amount of fuel injected from each fuel injection nozzle is temporally controlled by the pulse width of the injection pulse given by the control circuit, but in order for this control to be performed correctly, the fuel pressure applied to the fuel injection nozzle and the intake passage are A certain pressure difference is required between the internal pressure and the internal pressure. However, the boost pressure (
(positive pressure) is added, and this supercharging pressure increases as the supercharger driving force increases, so the above pressure difference fluctuates depending on the operating condition, making it difficult to perform appropriate fuel injection amount control.
The drawback was that fuel injection was actually hindered during high loads when a large amount of fuel was required.

In addition, as a fuel control means when attaching fuel injection nozzles to each of these two intake systems, it is possible to install a fuel supply pump etc. in two systems separately, but this would complicate the structure and It has the disadvantage of high cost.

In view of these circumstances, the present invention prevents a rise in intake air temperature during supercharging by providing fuel injection nozzles in each of the main intake system and the auxiliary intake system, and injects fuel into each fuel injection nozzle from one fuel pump. To provide a fuel control device for an engine that can appropriately control the amount of fuel injected from each fuel injection nozzle while maintaining a simple structure of a fuel supply system by distributing and supplying fuel.

That is, the present invention provides a partial supercharging type engine in which a first intake system is provided in a main intake system and an auxiliary intake system, respectively. Second
each fuel injection nozzle; Second
One fuel supply pump that distributes and supplies fuel at a predetermined ratio through each branch passage, and a fuel supply pump that is installed in each branch passage and adjusts the fuel pressure of each fuel injection nozzle according to the increase in intake pressure of each intake system. A fuel pressure regulating valve is provided to increase the fuel pressure.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 1 is the engine cylinder, 2 is the piston,
3 is a combustion chamber formed in the upper part of the cylinder 1. A main intake port 4, an auxiliary intake port 5 and an exhaust port 6 are open in the combustion chamber 3, and each of these ports 4.5.6 is equipped with a main intake intervention auxiliary intake valve 8 and an exhaust valve 9, respectively. There is.

11 is a main intake passage, 12 is an auxiliary intake passage, and each intake passage 11.12 branches from the intake passage upstream gathering part 13,
It communicates with the main intake port 4 and the auxiliary intake port 5, respectively. A throttle valve 14 is disposed in the main intake passage 11, while a supercharger 15 is disposed in the auxiliary intake passage 12, and a supercharging valve 16 that opens when the load exceeds a set value is disposed. ing. Also,
The main intake valve 7 is opened during the intake stroke, while the auxiliary intake valve 8 is opened at the end of the intake stroke or at the beginning of the compression stroke, and closed during the compression stroke. In this way, when the set load of the engine is exceeded, supercharging air is supplied from the auxiliary intake system at least during the compression stroke in addition to fresh air from the main intake system. Further, an air cleaner 17 and an air 70 meter 18 are provided in the intake passage upstream collecting section 13, and an intake flow rate detection signal from the air flow meter 18 is sent to a fuel injection amount control circuit 19, and the intake flow rate is adjusted in the control circuit 19. A corresponding fuel injection pulse is output.

21 is a first fuel injection nozzle provided in the main intake passage 11, and 22 is a second fuel injection nozzle provided in the auxiliary intake passage 12, each of which is connected to the control circuit.

It is opened by the fuel injection pulse output from 19.

Fuel is distributed and supplied to each fuel injection nozzle 21, 22 from one fuel supply pump 25 via first and second branch passages 31 to 32. That is,
A fuel supply passage 30 communicating with the fuel tank 26 is provided with a fuel supply pump 25 and a filter 27,28,
A fuel passage is piped from this part to each cylinder of the engine, and a first fuel passage is provided for each cylinder. A second respective branch passage 31,32 is provided. Each of the branch passages 31.32 is connected to each of the fuel injection nozzles 21.22, and the first branch passage 31 is provided with a constriction portion 36, so that each of the fuel injection nozzles 21.22 has a predetermined ratio. The fuel is distributed and supplied.

Further, each of the branch passages 31.32 is connected to a fuel tank,
A fuel relief passage 34°35 is provided leading to 26;
Fuel pressure regulating valves 36 and 37 are provided in each of the fuel relief passages 34 and 35, respectively. Each fuel pressure regulating valve 3.
! For example, as shown in the figure, S, 37 is a diaphragm type valve body 36g that is displaced according to the pressure difference between the fuel pressure and the intake pressure.
, 37a. That is, the valve body 36a
.

A communication chamber 36b to the downstream side of the relief passage is provided on one side of 37a.
, 37b and the communication chambers 3Sb and 37b.
The open end of the upstream portion of the J-F passage is arranged, and this open end is connected to the valve body 3. /)a, 37a, and a communication passage 3 is provided on the other side of the valve body 36a, 37m.
Intake pressure chambers 36c and 37Q are formed which communicate with each intake passage 1112 via 8.39, and the intake pressure chambers 36c and 37
Adjustment springs 36d and 37d are provided at C. The valve bodies 36a, 37a respond to the fuel pressure of each fuel injection nozzle 21, 22 received from both sides thereof and the intake pressure of each intake passage 11, 12, and if the intake pressure increases, the relief passage 3
4.35 is closed to increase the fuel pressure, and when the intake pressure decreases, the relief passage 34.35 is opened and the fuel pressure is also reduced. As a result, the pressure difference between the fuel pressure and the intake pressure remains constant. I try to keep it that way. This force difference is set in advance by the adjustment springs 3Sd and 37d.
.

Next, the operation of this device will be explained.

Air intake into the combustion chamber 3 of the engine is carried out only from the main intake passage 11 when the load is below the set load, but when the load exceeds the set load, supercharging is carried out from the auxiliary intake passage 12 in addition to the intake air from the main intake passage 11. Supercharging air is supplied with the pressure provided by the engine 15.

During this supercharging, the first. Each second fuel injection nozzle 21.2
Fuel is injected into each intake passage 11.12 from both sides of 2,
In the auxiliary intake system, the latent heat of vaporization of the injected fuel prevents the intake air temperature from rising excessively.

In this case, fuel is distributed and supplied to each of the fuel injection nozzles 21 and 22 at a predetermined ratio by the fuel supply pump 25, and is applied to each of the fuel injection nozzles 21 and 22 by each of the fuel pressure regulating valves 66°37. Fuel pressure in each intake passage 11
．． It is controlled to be increased in accordance with an increase in the intake pressure in 12. As a result, especially in the auxiliary intake system,
Even if the pressure in the auxiliary intake passage 12 (supercharging pressure) changes greatly due to the driving force number of the supercharger 15, which changes depending on the engine load, the fuel pressure changes accordingly, and the difference between the fuel pressure and the intake pressure The pressure difference is kept constant. Therefore, even during high loads where boost pressure increases, the above pressure difference is maintained appropriately.
The fuel injection amount is controlled in correct response to the injection pulse given by the control circuit 19 without interfering with the fuel injection. Also, in the main intake system,
When the intake pressure in the main intake passage 11 changes, the fuel pressure applied to the first fuel injection nozzle 21 changes accordingly, and the fuel pressure applied to the second fuel injection nozzle 22 of the auxiliary intake system changes accordingly. However, the pressure difference between the fuel pressure and the intake pressure is kept constant, and the fuel injection amount is accurately controlled without being affected by this.

As explained above, the present invention provides a partial supercharging type engine in which fuel is supplied to each of the first and second fuel injection nozzles provided in the main intake system and the auxiliary intake system, respectively, using a single fuel supply pump. At the same time, the fuel pressure adjustment valve provided for each fuel injection nozzle controls the fuel pressure of each fuel injection nozzle to increase in accordance with the increase in intake pressure of each intake system. Although the structure is simple, it is possible to maintain an appropriate pressure difference between the fuel pressure of each fuel injection nozzle and the intake pressure in both the main intake system and the auxiliary intake system equipped with a supercharger. This can be achieved by correctly controlling the fuel injection amount.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an embodiment of the invention. 11... Main intake passage, 12... Auxiliary intake passage, -1
5...Supercharger, 21...First fuel injection nozzle, 22
...Second fuel injection nozzle, 25...Fuel supply pump, 61...First branch passage, 32...Second branch passage,
66゜'57...Fuel pressure adjustment valve. Patent applicant: Toyo Kogyo Co., Ltd.

Claims (1)

[Claims] 1. The engine intake system consists of a main intake system and an auxiliary intake system, and a supercharger is installed in the auxiliary intake system, so that when the engine load exceeds the set load, fresh air from the main intake system is supplied at least during the compression stroke. In the engine in which supercharging air is supplied from the auxiliary intake system, a first fuel injection nozzle and a second fuel injection nozzle provided in the main intake system and the first auxiliary intake system, respectively; one fuel supply pump that distributes and supplies fuel to the two fuel injection nozzles at a predetermined ratio through the first and second branch passages; and a fuel pressure regulating valve that controls the fuel pressure of the second fuel injection nozzle to increase in accordance with an increase in the intake pressure of each intake system.