JPH0480231B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is provided with two intake passages communicating with a combustion chamber, and one of the intake passages is equipped with an on-off valve for opening and closing the passage. Regarding injection type engines.

(Prior Art) Engines are known that have an intake structure including a fuel injection valve and a plurality of intake passages communicating with a combustion chamber. For example, the structure described in Japanese Patent Application Laid-Open No. 54-39721 includes a low-load intake passage leading to the combustion chamber and a high-load intake passage formed above the low-load intake passage. is equipped with an on-off valve that closes the passage when the load is low. The fuel injection valve is arranged downstream of the on-off valve in the high-load intake passage so that the injected fuel does not interfere with the opening/closing operation of the on-off valve. In this structure, when the on-off valve closes, the flow velocity of the intake air that can flow through the high-load intake passage decreases, resulting in insufficient atomization of the fuel. To avoid this problem, the fuel injection valve is placed in the low-load intake passage, so that the low-load intake passage forms a relatively shallow angle with the combustion chamber.
That is, it is oriented almost horizontally, so
It becomes difficult to direct the fuel injection direction to the fuel chamber. Furthermore, since the intake air flow in the low-load intake passage does not become very strong even under high loads, there is a problem in that the efficiency of atomization during high loads decreases. Also,
In the structure described in Utility Model Application Publication No. 55-4355, 1
a low-load intake passage and a high-load intake passage communicating with two intake ports, the fuel injection valve is configured so that fuel injection is performed near the confluence of the low-load intake passage and the high-load intake passage, Fuel is injected into the intake air flow from low to high loads to promote atomization. However, with this structure, the fuel is injected very close to the combustion chamber, so
Not being able to achieve sufficient mixing of the intake air.

(Objective of the present invention) Therefore, the object of the present invention is to provide good fuel vaporization and good fuel vaporization over a wide operating range from low load to high load in an engine equipped with two intake passages and on-off valves.
In addition to being able to provide atomization and mixing conditions,
An object of the present invention is to provide a fuel injection engine capable of promoting the generation of swirl in a low load operating region.

(Configuration of the present invention) In order to achieve the above object, the present invention is configured as follows. That is, the fuel injection engine according to the present invention has a main intake passage that supplies intake air to a combustion chamber, a throttle valve provided in the main intake passage, and a throttle valve provided downstream of the throttle valve in the main intake passage. an on-off valve that is controlled to close in a low-load operating range and open in a high-load operating range; one end of the on-off valve opens into the main intake passage upstream of the on-off valve and downstream of the throttle valve; and the other end of the on-off valve A fuel injection type engine comprising: an auxiliary intake passage that opens near the combustion chamber downstream of the valve; and a fuel injection valve provided such that its tip faces into the main intake passage immediately downstream of the on-off valve. An air bleed passage is provided, one end of which opens into the main intake passage upstream of the on-off valve and downstream of the throttle valve, and the other end of which opens near the tip of the fuel injection valve; The other end opening near the combustion chamber is tangential to the cylinder diameter and opening substantially horizontally. When the on-off valve is closed, that is, when the load is relatively low, the air from the air bleed passage is injected toward the injected fuel within the range of the intake pressure in the intake passage downstream of the throttle valve. This facilitates fuel atomization and mixing at low loads.

Since this air is ejected by the pressure downstream of the throttle valve, air bleed can be performed in accordance with the throttle opening. Therefore, there is no need to worry about unduly introducing excessive air under low load conditions. Furthermore, in a relatively high-load operating range where the on-off valve is wide open, the intake air flow flowing through the main intake passage is strong, so that the injected fuel comes into contact with this intake air flow, thereby promoting atomization. Furthermore, the other end of the auxiliary intake passage that opens near the combustion chamber is provided so as to open tangentially to the cylinder diameter and in a substantially horizontal direction. It becomes possible to promote the generation of swirl in the low-load operation region where the fuel is supplied to the fuel. An intake structure to which the present invention can be applied does not necessarily have to include a plurality of intake ports, and may have two intake passages leading to one intake port.

As a means for introducing intake air to the downstream side of the on-off valve, it is possible to provide an air bleed passage that communicates the upstream side of the valve with the intake passage on the downstream side. moreover,
An air bleed passage may be formed that communicates the intake passage on the upstream side of the throttle valve and the intake passage on the downstream side of the on-off valve. If this latter method is used, intake air can be constantly supplied toward the injected fuel.

(Example) Referring to FIGS. 1 and 2, engine E
is a cylinder block 1 having a cylinder pore 1a.
The engine has a cylinder head 2 attached to the upper part of the cylinder block 1, and a piston 3 is disposed within the cylinder bore 1a so as to be able to reciprocate in the axial direction, thereby forming a combustion chamber 4 within the cylinder bore 1a. The cylinder head 2 has first and second intake ports 5, 6.
and an exhaust port 7 are formed, an intake valve 8 is formed in the first and second intake ports 5 and 6, and an exhaust port 7 is formed in the first and second intake ports 5 and 6, respectively.
An exhaust valve 9 is attached to the. Referring to FIG. 1, the first and second intake ports 5 and 6 have approximately the same diameter;
Cylinder center line l in the width direction of cylinder block 1
The exhaust port 7 is arranged at a position facing the second intake port 6 across the longitudinal centerline m of the cylinder block 1.

The intake system has a main intake passage 11 extending from an air cleaner 10, and a throttle valve 12 is disposed within the main intake passage 11. As shown in FIG. 1, the main intake passage includes a surge tank 24 in the middle, extends into the cylinder head 2, and extends approximately along the cylinder center line l in the width direction of the cylinder block in the vicinity of the intake ports 5 and 6. First and second branch passages 1 are separated by a partition wall 14 formed as follows and communicate with first and second intake ports 5 and 6, respectively.
5 and 16. The exhaust port 7 is connected to the exhaust passage 17 to constitute an exhaust system. This exhaust system may have a normal configuration. In the main intake passage 11,
A fuel injection valve 23 is arranged upstream of the partition wall 14, and fuel calculated based on a signal corresponding to engine operating conditions is supplied to the combustion chamber 4. An on-off valve 18 is provided within the main intake passage 11 .
The opening/closing valve 18 is, for example, linked to the throttle valve 12 so that it is closed in a low-load operating region where the throttle valve has a relatively small opening, and is opened when the throttle valve 12 is opened beyond a predetermined opening. configured.

Furthermore, an opening 19 is formed in the main intake passage 11 slightly upstream of the on-off valve 18, and an auxiliary intake passage 20 is formed extending below the main intake passage 11 from this opening 19. Auxiliary intake passage 20
is from the bottom of the main intake passage 11 to the first branch passage 15.
through the opening 21 of the first intake port 5.
It is connected to the. Further, an air bleed passage 25 is provided above the on-off valve 18 of the main intake passage 11, and the upstream end of this air bleed passage 25 is connected to the on-off valve 18 of the main intake passage 11 by an opening 26.
It is connected to the upper part on the upstream side. Referring also to FIG. 3, a fuel injection valve 23 is arranged slightly above the on-off valve 18 on the downstream side, and a socket 27 is fitted around the nozzle tip 23a. . The socket 27 has a peripheral groove 2 on its outer periphery.
7a, and the groove 27a is provided with a plurality of small holes 27b spaced apart in the circumferential direction. The downstream end of the air bleed passage 25 communicates with this peripheral groove 27a. Therefore, the air introduced into the air bleed passage 25 is blown out from the small hole 27b toward the inside of the socket 27, thereby efficiently atomizing the injected fuel.

As shown in FIG. 2, the first intake port 5 is
In order to ensure a high filling amount during high-load operation, the cylinder bore 1a opens into the combustion chamber 4 at an angle close to the axial direction.Although not shown in the figure, the second intake port 6 also has a similar shape. be. On the other hand, since the auxiliary intake passage 20 opens to the first intake port 5 from below the main intake passage 11 and the first branch passage 15, it is oriented at a relatively shallow angle with respect to the combustion chamber 4. . Furthermore, since the first intake port 5 is arranged to be biased to one side with respect to the center line l of the cylinder bore 1a, the intake air jetted into the combustion chamber 4 at a shallow angle from the auxiliary intake passage 20 is directed within the combustion chamber 4. Generates a strong swirl in the horizontal plane.

As shown in FIG. 1, in this embodiment, a portion of the cylinder head 2 where intake and exhaust ports are not formed, that is, a portion facing the first intake port 5 across the longitudinal centerline m of the cylinder block 1. A spark plug 22 is attached to the portion. Therefore, since the ignition plug 22 is located on the swirl locus formed by the intake air flow from the auxiliary intake passage 20, fresh air-fuel mixture is reliably supplied to the vicinity of the ignition plug 22, resulting in a good air-fuel mixture. Combustion occurs with ignitability.

In the low-load operation region, the on-off valve 18 is closed or has a small opening, and intake air is mainly introduced into the combustion chamber 4 from the auxiliary intake passage 20. In this case, fuel is injected toward the main intake passage 11, but some intake air is injected from the small hole 27b through the air bleed passage 25 toward the fuel injected from the fuel injection valve 23, resulting in fuel mist. promote the development of Since this air is ejected by the pressure downstream of the throttle valve 12, air bleed can be performed in accordance with the throttle opening degree. Therefore, there is no need to worry about unduly introducing excessive air under low load conditions. Further, in a high-load operation region, the on-off valve 18 is in an open state, and fuel is injected into the intake air flow, thereby promoting atomization of the fuel.

(Effects of the Invention) According to the present invention, in a low load region, intake air can be introduced at high speed through the auxiliary intake passage to form a swirl, and the air from the air bleed passage can be used to reduce intake air. Good atomization, vaporization and mixing conditions can be ensured. Since this air is ejected by the pressure downstream of the throttle valve, air bleed can be performed in accordance with the throttle opening. Therefore, there is no need to worry about unduly introducing excessive air under low load conditions. On the other hand, in high-load regions, atomization is promoted by the intake air flowing through the main intake passage, making it possible to obtain good atomization and mixing conditions over the entire operating range, improving fuel efficiency and driving performance. can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an engine intake system showing an embodiment of the present invention, FIG. 2 is a vertical sectional view of an engine embodying the present invention, and FIG. 3 is an enlarged view of part A in FIG. be. 1... Cylinder block, 1a... Cylinder bore, 2... Cylinder head, 3... Piston, 4
...Combustion chamber, 5, 6...Intake port, 7...Exhaust port, 11...Main intake passage, 12...Throttle valve, 15, 16...Branch intake passage, 18...Opening/closing valve, 19... Opening, 20...Auxiliary intake passage, 2
5...Air bleed passage.

Claims (1)

[Claims] 1. Main intake passage 11 that supplies intake air to the combustion chamber 4
, a throttle valve 12 provided in the main intake passage 11, and a throttle valve 12 provided downstream of the throttle valve 12 in the main intake passage 11, which is controlled to close in a low load operating region and open in a high load operating region. an on-off valve 18 with one end opening into the main intake passage 11 upstream of the on-off valve 18 and downstream of the throttle valve 12, and an auxiliary intake passage 20 with the other end opening downstream of the on-off valve near the combustion chamber. and the on-off valve 18
a fuel injection valve 23 provided such that its tip faces into the main intake passage 11 directly downstream of the throttle valve 12; An air bleed passage 25 is provided which opens into the main intake passage 11 downstream of the auxiliary intake passage 20 and whose other end opens towards the vicinity of the tip of the fuel injection valve 23, and which opens in the vicinity of the combustion chamber 4 of the auxiliary intake passage 20. A fuel injection engine characterized in that the end opens tangentially to the cylinder diameter and substantially horizontally.