DE3044200A1 - CYLINDER HEAD FOR SELF-PRIMING COMBUSTION ENGINES - Google Patents

Description

30442QQ

Cylinder head for self-priming combustion engines

The invention relates to cylinder heads for self-priming, spark-plug-ignited engines with internal combustion.

It is known to provide two inlet valves per cylinder for such engines, and to ihderung the performance of the engine at different speeds it has been ^{proposed according to GB-} PS 989 166, the fuel-air supply to one of the inlet valves for each cylinder as a function of the Engine speed to lock. Thus, this patent describes an engine with two intake manifolds, one of which communicates via intake ports with one of the intake valves for each cylinder and the other via intake ports to the other of the intake valves for each cylinder. A throttle valve in one of the intake manifolds can be closed below certain engine speeds so that each cylinder is only fed from one intake valve. When the engine exceeds a predetermined speed, the valve in the intake manifold opens, so that each cylinder is then charged via both intake valves and a greater work output is achieved. However, this arrangement has the disadvantage that it has poor response to the throttle lever when the speed reaches the level at which the throttle valve opens to operate both intake valves.

The invention is based on the task of providing a device when it is put into operation the additional intake paths to create a more spontaneously appealing cylinder head. The inventive solution to this The task is characterized in claim 1.

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By arranging the means for closing which the fuel-air mixture to the cylinders via one of the intake valves, in each intake port instead of in the intake manifold a better response to throttle pressure can be achieved. The reason for this is that after the lockable Inlet valves have been closed, the space above these inlet valves up to the means of closing, d. H. between the closable inlet valves and the corresponding means for closing, filled with exhaust gases is and, if the means for closing is subsequently opened, the exhaust gases first into the combustion chamber be sucked. In the known arrangement described above, the exhaust gases fill the entire space the intake pipe to the throttle valve, and there is then a significant amount of the consumed mixture in the combustion chamber sucked in. By providing a separate closing means in the intake port itself for each cylinder the volume of such consumed mixture is significantly reduced. As a result, it becomes a significantly faster Responding with the arrangement according to the invention as. achieved with that of the known type.

The closable inlet channel is preferably designed so that it closes below a certain engine speed. Furthermore, it is advantageous that the valve of the closable inlet channel has a larger diameter than the valve of the other inlet port. Accordingly, the invention allows the use of a valve with a low Diameter at low engine speeds, allowing better mixing and thereby the use of a leaner mixture results in greater performance while taking advantage of a larger intake port area at high engine speeds can be obtained. The use of a relatively long inlet channel is also possible. Previously, the Engine valve area could not be varied, and a choice had to be made between a small valve area that allows for good mixing

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and gives high performance at low engine speed, but by diminished volumetric efficiency and diminished Performance at high engine speeds will be compromised, and a large valve area will be hit, which is a gives good volumetric efficiency and good performance at high engine speeds, but has the disadvantage of knocking and a reduced performance at low engine speed. Preferably the closable inlet channel is so designed so that it opens in the speed range at which the volumetric efficiency of the engine as a result of the smaller inlet port begins to fall. It is also advantageous if the stroke and / or the opening duration of the inlet valve of the closable inlet channel is larger than that of the other intake valve.

Two separate suction pipes can be provided, one of which leads to the closable inlet ducts and the other to the others Inlet ports leads, but it is preferred to have a single intake manifold leading to all of the inlet ports.

Preferably, the closable inlet channels through the use of a single valve member, for example one Rotary flap valve in the corresponding inlet channel closed.

A single exhaust valve per cylinder can be used or, if necessary, two exhaust valves per cylinder can be used be provided. In the latter case, the opening leading to one of these valves can be closable.

With reference to the drawing, a cylinder head for a self-priming, spark-plug-ignited, with liquid Fuel-powered four-stroke engine, which is an embodiment of the invention, described in more detail.

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Fig. 1 is a plan view of the valves of a cylinder a motor;

Fig. 2 is a section along the line A-A in Figs FIG. 3 is a section along line B-B in FIG. 1.

With reference to the drawing, the cylinder head has two intake and two exhaust valves per cylinder.

A single camshaft or control shaft 1 acts directly on the two intake valves 2 and 3 via conventional valve stem caps or cups 4 and adjustable valve stems 5. The inlet valves have different plate diameters, and the lift and the periods of the control devices (cams) are designed to be adapted to the corresponding valve sizes.

The inlet valve 2 in FIG. 2 is shown with a large plate diameter and a correspondingly large inlet opening 6. The control device (cam) 7 for operating this valve has a long opening time and a large stroke for high power and high speed. The inlet valve 3 in Fig. 3 has a much smaller plate diameter and is fed through an inlet opening 8 with a small diameter. Both inlet openings 6 and 8 are connected to an intake pipe. The profile of the control device (cam) 9, which operates this intake valve 3, is selected in such a way that it has high torque characteristics at low engine speeds and operability with a lean fuel-air mixture ratio.

To the advantages of the inlet valve 3 and the control device profile 9 at low engine speed according to the present invention

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The effect of the larger inlet valve and the longer duration of the control device (cam) 7 are canceled, by closing the inlet opening 6 and the inflow of the intake charge into the engine via this valve and this Inlet opening is prevented at low speed. Fig. 2 shows a simple throttle valve 10 which is in the inlet port is arranged to achieve blocking of the inlet valve. However, this blocking is not on use a throttle valve, but other types of open / closed valve are possible.

The engine is effectively idling and idling at low to medium speed with only one inlet valve operating per cylinder. The variable inlet conditions can be controlled by different signals and provide one high degree of adaptability for power and knock limit control of the engine.

In addition, the smaller intake valves and intake ports Be placed side by side on adjacent cylinders in a multi-cylinder engine and close to the carburetor To provide a low volume air intake manifold that is beneficial for a cold start and quick warm up can be used.

The outflow of exhaust gases from the cylinder can be different Way. One can have a single large valve and an opening that is by means of a rocker arm from the intake cam be operated, or - as shown in Fig. 1 - use two separate valves 11 and 12, which by means of a three-finger rocker arm 13 are operated by the inlet cam 7. If necessary, two separate valves and exhaust ports can be used can be provided by two individual rocker arms

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are operated by the two inlet cams 7 and 9. the The latter embodiment would include different exhaust valve timing and the provision of an open / closed valve in the exhaust port 14 to allow in a cascading arrangement to work with the throttle valve 10. Typical valve sizes are 25.4 mm for the larger valve and 12.7 mm for the smaller valve on an engine with a cylinder bore of 70 mm.

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Claims (7)

Cylinder head for self-priming combustion engines Claimed Priority: November 23, 1979, UK, No. 79 40 Expectations Cylinder head for self-priming combustion engines with two inlet valves per cylinder, characterized in that for each of the two inlet valves (2, 3) a corresponding, with a suction pipe connected inlet channel (6; 8) is provided and that in one of the inlet channels (6) for each Cylinder a means for closing (10) this inlet channel (6) independently of the other inlet channel (8) of the relevant Cylinder is provided. 2. Cylinder head according to claim 1, characterized in that the closable inlet channel (6) than below one specific engine speed closing is provided. ORIGINAL INSPECTED 130023/0666 POST CHECK ACCOUNT: MÖNCHEN 50175-609 BANK ACCOUNT: DEUTSCHE BANK A.Q. MÖNCHEN, LEOPOLDSTRASSE 71, ACCOUNT NO. 60/35794 304420Q 3. Cylinder head according to claim 1 or 2, characterized in that the inlet valve (2) of the closable inlet channel (6) has a larger diameter than the inlet valve (3) of the other inlet channel (8). 4. Cylinder head according to one of claims 1 to 3, characterized in that the stroke and / or the opening duration of the inlet valve (2) of the closable inlet channel (6) is larger than that of the other intake valve (3). 5. Cylinder head according to one of claims 1 to 4, characterized in that a single intake pipe with all inlet channels (6; 8) is in communication, is provided. 6. Cylinder head according to one of claims 1 to 4, characterized characterized in that the means for closing (10) the inlet channels (6) a single valve part (10) in the corresponding inlet channel (6) is. 7. Cylinder head according to claim 6, characterized in that the valve part (10) is a flap valve. 130023/0666