GB2079363A

GB2079363A - I.C. Engine cylinder intake passages

Info

Publication number: GB2079363A
Application number: GB8021126A
Authority: GB
Original assignee: Suzuki Motor Corp
Current assignee: Suzuki Motor Corp
Priority date: 1980-06-27
Filing date: 1980-06-27
Publication date: 1982-01-20
Also published as: GB2079363B

Abstract

To produce turbulence in the combustion chamber 11 the outlet 17 of a subsidiary intake passage 16 receiving fuel/air mixture, air and/or recirculated exhaust gas is located just upstream of the main carburetted mixture intake valve 14 to direct the received fluid in a particular direction in the combustion chamber, Figure 2 (not shown). Fluid flow to the passage 16 may be controlled by valves (24,35), Figures 3 to 6 (not shown), responsive to the vacuum immediately upstream of the carburettor throttle valve 14 or responsive to other engine operating conditions. Exhaust gas may also be supplied to the main intake passage 7 upstream of the outlet 17. The fluid may be supplied by a pump (38), Figure 7 (not shown). <IMAGE>

Description

SPECIFICATION Engine equipped with sub-suction path In the present invention which relates to an engine equipped with a sub-suction path, said sub-suction path smaller in diameter is provided separately from a main suction path and a jet flow ejected through said sub-suction path causes a swirl (orturbulence) in the cylinder, thereby improving the combustibility of a lean mix.

It is well-known that various harmful elements are contained in the emmission of the engine. It is therefore mandatory under law to hold down the emitted volume of these harmful elements to specified extents. A number of methods have been devised and practically applied to reduce the harmful contents in the emission gas. A method of making the mixed gas lean and burning such a lean mix is one of the effective means conceivable for this purpose, but the conventional mechanism in this method to assure satisfactory combustion of the lean mix is so complicated that its simplification has been a pending problem.

Summary of the invention The object of the present invention is to provide an engine with a sub-suction path that can burn a lean mix in a simple mechanism.

According to the present invention there is provided an engine with a sub-suction path, characterized in that in addition to a main suction path running from a carburatorto a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before the suction valve and its inlet located uptstream of a throttle valve of the carburetor where the pressure is high.

Further according to the present invention there is provide an engine with a sub-suction path, characterized in that in addition to a main suction path running from a carburetor to a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before a suction valve and its inlet being connected to an EGR (exhaust gas recycle) pipe.

Also according to the present invention there is provided an engine with a sub-suction path, characterized in that in addition to a main suction path leading from a carburetor to a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before a suction valve and its inlet being connected to an EGR pipe and down stream of the throttle valve of the carburetor.

Further according to the present invention there is provided an engine with a sub-suction path, characterized in that in addition to a main suction path leading from a carburetorto a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before a suction valve and its inlet being connected to upstream side, where the pressure is high, of a throttle valve of the carburetor and to an EGR pipe.

Also according to the present invention there is provided an engine with a sub-suction path, characterized in that in addition to the main suction path leading from the carburetor to the suction port of the cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before the suction valve and its inlet being connected to the inlet of an air pump.

The present invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic section view of a first embodiment of the present invention; Figure 2 (a) is a schematic plan view showing the opening direction of a sub-suction path of the first embodiment into a combustion chamber.Figures 2 (b) to (d) show modifications of Figure 2 (a); Figure 3 is a schematic section view of a second embodiment of the present invention; Figure 4 is a schematic section view of a variation of the second embodiment of the present invention; Figure 5 is a schematic section view of a third embodiment of the present invention; Figure 6 is a schematic section view of a variation of the third embodiment of the present invention; and Figure 7 is a schematic section view of a fourth embodiment of the present invention.

Detailed description ofthe invention The present invention has been accomplished as a solution to the pending problem mentioned above.

Referring to the attached drawings, here is to be described the present invention. In Figure 1 illustrating a first embodiment of the invention, 1 is an air cleaner; 2 is a carburetor; 3 being its venturi; 4 is a throttle valve; 5 is an engine, 6 being its cylinder head; 7 is a main suction path; and 8 is an exhaust path.

The carburetor 2 communicates with the main suction path 7.9 is a cylinder; 10 is a piston; and 11 is a combustion chamber. In the main suction path 7 at the cylinder head 6 and at the opening of the exhaust path 8 into the combustion chamber 11 there are installed valve seats 12, 13, where a suction valve 14 and an exhaust valve 15 are arranged to be operated by cams not shown so that they can attach to or detach from said valve seats repeatedly.

16 is a sub-suction path, which, being provided separately from the main suction path 7, has a smaller diameter and a less wide sectional area than the main suction path 7. The outlet of said subsuction path 16 is located just behind the suction valve 14 provided at the opening of the main suction path 7 and its inlet is located upstream of the throttle valve 4 of the carburetor 2, where the pressure is high.

Said inlet may be located upstream oftheventuri 3, as indicated by a broken line in the drawing. The outlet from the sub-suction path 16 communicates with a pipe 17 driven into the cylinder head 6, thereby constituting a jet hole. Said pipe 17 may be screwed into the cylinder head 6 instead of being driven in; or it may be formed by casting. Instead of using the pipe 17 like this, the outlet from the sub-suction path 16 may be simply constituted by a hole; and its location may be at the valve seat 12, which is lower than the location in Figure 1.

Figures 2 (at to (d) illustrate the opening directions of the sub-suction path into the combustion chamber and they indicate the angle of the outlet of the sub-suction path 16 to the cylinder 9 or the angle of the pipe 17 to the cylinder 9. In the illustration 2 (a), the main suction path 7 and the sub-suction path 16 are arranged vertically one above the other, the outlet of the sub-suction path 16 being directed approximately toward the spark plug 18. Thereby, the jet flow going in the arrow direction from the sub-suction path 16 into the combustion chamber 11 generates a swirl.

In the illustration 2 (b), the location of the subsuction path 16 is staggered from that of the main suction path 7, with the outlet of said path 16 bent in the direction of the wall surface of the cylinder 9; and thereby the jet flow goes in the arrow direction.

In the illustration 2 (c) the outlet of the sub-suction path 16 is directed slightly inside as compared with the illustration 2 (b); and thereby the jet flow moves in the arrow direction.

In the illustration 2 (d), unlike (b) or (c), the outlet of the sub-suction path 16 is directed in the direction between the spark plug 18 and the exhaust path 8; and thereby the jet flow moves as indicated by the arrow. In any of these cases, a swirl (or turbulence) develops and a scavenging around the spark plug takes place. (The illustration on Figures 2 (a) to (d) is applicable to the embodiments in Figures 3 to 7).

In these cases the angle of the sub-suction path 16 in the vertical direction to the combustion chamber 11 of the cylinder 9 is so arranged, as indicated by an arrow mark with a broken line in Figure 1,that the jet flow may approximately pointtoward the combustion chamber 11 when the suction valve 14 opens.

In an engine with this arrangement, a highpressure mixed gas is ejected into the combustion chamber 11 when the suction valve 14 is opened.

Since the sub-suction path 16 has a smaller diameter and a less wide sectional area, the flow velocity increases, causing a violet swirl (or turbulence), which assures satisfactory burning of even a lean mix.

Figure 3 illustrates a second embodiment of the invention. In this embodiment an EGR valve 19 is provided, its inlet being connected midway in the exhaust path 21 through the EGR pipe 20 and its outlet being connected to the sub-suction path 16. 22 is an emission gas purifier. Said EGR valve 19 has its valve 24 opened when the diaphragm 23 is exposed to a negative pressure, said negative pressure being conveyed via the pipe 25 to the portion just above the throttle valve 4 of the carburetor 2.

In an engine with this arrangement, a negative pressure which is variable with the open degree of the throttle valve 4 actuates the diaphragm 23; when the negative pressure exceeds a specific limit, the valve 24 begins to open, thereby ejecting a portion of the exhaust gas into the combustion chamber 11 through the sub-suction path 16. Under a light loading with a high negative pressure of suction (boost pressure), the exhaust gas recycle rate (EGR rate) rises, making the combustion liable to instability; however, the sub-suction path 16 having a smaller diameter and accordingly the jet flow velocity being high,the swirl becomes strong and in consequence the stability of combustion is restored.

Figure 4 illustrates a variation of the second embodiment of the invention. In this case a second EGR valve 26 is provided and the EGR pipe 20 branches out to introduce a portion of the exhaust gas via the pipe 27 to downstream of the throttle valve 4. The second EGR valve 26 too is actuated by a negative pressure conveyed by the pipe 28 to downstream of the venturi 3.

In this embodiment it can be arranged through appropriate change in the location of the working points of the two EGR valves 19, 26 such that under a light loading the exhaust gas goes from the subsuction path 16 into the combustion chamber 11 only, while under a high loading the exhaust gas goes either into the main suction path 7 or into both the main suction path 7 and the sub-suction path 16.

Figure 5 illustrates a third embodiment of the invention. In this embodiment, in addition to the EGR valve 19 a gas flow rate control valve 29 to control the air (or mixed gas) is provided, the inlet side of said valve 29 being located downstream of the venturi 3 through the pipe 30 and the outlet side of it being connected to the sub-suction path 16 through the pipe 31. Meanwhile the sub-suction path 16 connects to the outlet side of the EGR valve 19 through the pipe 32 which branches out from the pipe 31. The gas flow-rate control valve 29 is connected through the pipe 33 so that it can act by a boost pressure working in the main suction path 7, 34 being a diaphragm and 35 being the valve assembly. Thus in this engine, exhaust gas and air (or mixed gas) are admitted into the sub-suction path 16, thereby causing a swirl (or turbulence) in the combustion chamber.

Figure 6 illustrates a variation of the third embodiment of the invention. In this case, instead of using an air control valve, the outlet side of the EGR valve 19 is located through the pipe 36 midway in the sub-suction path 16 which connects downstream of the venturi 3 to just behind the suction valve 14.

Thereby the EGR valve 19 has its junction on the control side connected via the pipe 37 to a signal booster not shown, so that said valve 19 can act depending on the conditions such as the temperature of the engine-cooling water, the engine revolutions or the load. In this engine too, the fluid to cause a swirl (or turbulence) in the combustion chamber 11 will be both the exhaust gas and air.

Figure 7 illustrates a fourth embodiment of the invention. In this case the sub-suction path 16 is connected to an air pump 38 for emission gas purification so that both the air and the exhaust gas from the EGR pipe 20 may be sent to the combustion chamber 11. The air pump may be one intended for any other purpose. Thus in this engine a swirl (or turbulence) can be effectively generated by a simple mechanism.

Such being the constitution of the invention, a swirl (or turbulence) can be effectively produced within the cylinder by a simple mechanism, thereby enhancing the combustiblity of a lean mix and minimizing the harmful content of the emission gas.

Claims

1. Engine with a sub-suction path, characterized in that in addition to a main suction path running from a carburetor to a suction port of a cylinder, a sub-suctiion path of smaller diameter is provided, its outlet being located just before the suction valve and its inlet located upstream of a throttle valve of the carburetorwherethe pressure is high.

2. Engine of claim 1, wherein the outlet of said sub-suction path is directed toward a combustion chamber in the cylinder head.

3. Engine of claim 2, wherein said outlet is bent in the direction of a swirl generation in the combustion chamber.

4. Engine of claim 2, wherein said outlet is directed toward the spark plug in the combustion chamber.

5. Engine of claim 2, wherein said outlet is directed toward midpoint between a plug and an exhaust valve.

6. Engine with a sub-suction path, characterized in that in addition to a main suction path running from a carburetor to a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before the suction valve and its inlet being connected to an EGR pipe.

7. Engine of claim 6, wherein said outlet is directed toward a combustion chamber in a cylinder head.

8. Engine of claim 7, wherein an EGR valve whose open degree is controlled by a negative pressure of suction upstream of the throttle valve of the carburetor is provided between the sub-suction path and the EGR pipe.

9. Engine of claim 8, wherein said EGR valve consists of a diaphragm valve and a negative pressure chamber of said diaphragm valve is connected between the throttle valve and a venturi of the carburetor.

10. Engine of claim 7, wherein said EGR pipe is connected to the exhaust pipe upstream of the emission gas purifier.

11. Engine with a sub-suction path, characterized in that in addition to a main suction path leading from a carburetor to a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before a suction valve and its inlet being connected to an EGR pipe and downstream of the throttle valve of the carburetor.

12. Engine of claim 11, wherein said outlet is directed toward the combustion chamber in the cylinder head.

13. Engine of claim 12, characterized inthata first EGR valve with its open degree controllable by a negative pressure of suction upstream of the throttle valve of the carburetor is provided between the EGR pipe and the sub-suction path; and said EGR pipe and downstream side of the throttle valve of the carburetor are linked via a second EGR control valve with its open degree controllable by a negative pressure of suction upstream of the throttle valve of the carburetor.

14. Engine of claim 13, characterized in that said first EGR valve and said second control valve consist of a diaphragm valve and the negative pressure chambers of these valves are provided between the throttle valve and a venturi of the carburetor.

15. Engine of claim 13, characterized in that said EGR pipe is connected to the exhaust pipe upstream of an emission gas purifier.

16. Engine with a sub-suction path, characterized in that in addition to a main suction path leading from a carburetor to a suction port of a cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before a suction valve and its inlet being connected to upstream side, where the pressure is high, of a throttle valve of the carburetor and to an EGR pipe.

17. Engine of claim 16, wherein said outlet is directed toward a combustion chamber in a cylinder head.

18. Engine of claim 17, characterized in that an EGR valve with its open degree controllable by a negative pressure of suction upstream of the throttle valve of the carburetor is provided between the exhaust gas return pipe and the sub-suction path; and a gas flow-rate control valve with its open degree controllable by a negative pressure of suction downstream of the throttle valve of the carburetor is provided midway in a path or pipe which communicates said sub-suction path with an upstream point of higher pressure than upstream of the carburetor or upstream of the throttle valve of the carburetor.

19. Engine of claim 17, characterized in that an EGR valve with its open degree controllable by a negative pressure introduced into its negative pressure chamber is provided between the sub-suction path and the EGR pipe; and said negative pressure chamber of the EGR valve is connected to the negative pressure chamber of a negative pressure generator which detects the engine temperature, revolutions and load and thereby generates a negative pressure.

20. Engine of either claim 18 or claim 19, char- acterized in that said EGR pipe is connected to the exhaust pipe upstream of the emission gas purifier.

21. Engine with a sub-suction path, characterized in that in addition to the main suction path leading from the carburetor to the suction port of the cylinder, a sub-suction path of smaller diameter is provided, its outlet being located just before the suction valve and its inlet being connected to the inlet of an air pump.

22. Engine of claim 21, wherein said outlet is directed toward the comustion chamber in the cylinder head.

23. Engine of claim 21,wherein said air pump serves to supply the secondary air to the emission gas purifier installed midway in the exhaust pipe.

24. Engine with a sub-section path, substantially as hereindescribed with reference to and as illustrated in the accompanying drawings.