WO1994004802A1

WO1994004802A1 - Device for increasing the filling ratio of aspirating engines

Info

Publication number: WO1994004802A1
Application number: PCT/DE1992/000693
Authority: WO
Inventors: Hansbernd Berzheim
Original assignee: Hansbernd Berzheim
Priority date: 1991-02-18
Filing date: 1992-08-18
Publication date: 1994-03-03
Also published as: DE4227261A1

Abstract

The description relates to device for increasing the fresh gas filling ratio during the induction stroke of an internal combustion engine having a by-pass pipe (4) which interconnects the inlet pipe (2) of a combustion chamber (1) with the exhaust pipe (3) thereof or another combustion chamber in the immediate vicinity of the intake (6) and exhaust (7) apertures outside the combustion chamber, and a non-return valve (5) for the by-pass pipe (4) which closes the by-pass pipe (4) in synchronism with the opening of the inlet aperture (6) and opens at the earliest when the inlet aperture (6) closes. The connection between the by-pass pipe (4) and the exhaust pipe (3) takes the form of an exhaust gas ejector. This increases the fresh gas filling ratio on the intake stroke.

Description

Device for increasing the degree of filling of naturally aspirated engines

The present invention relates to a device for increasing the fresh gas filling during the intake or charging stroke of a clocked internal combustion engine with internal combustion without using a charger or compressor. The invention is applicable to engines that work according to the four-stroke or two-stroke principle and to those that work according to the Otto or diesel process. It is applicable to reciprocating as well as any type of rotary piston or other clocked working engines with internal combustion.

The torque and power of a clocked engine with internal combustion depend, among other things, on the so-called "fill level" of its work area. If no structural precautions are taken, the degree of filling of the work area decreases more and more with increasing speed due to the inertia of the intake air and the increasingly shorter intake time, and thus the torque and the output of the engine decrease.

To prevent this, the timing of the intake and exhaust valves is adjusted so that the intake valves in engines with actively controlled valves, for example in four-stroke reciprocating engines open if the exhaust valves are not yet closed. This is called "valve overlap". This overlap causes the outflowing exhaust gases to have a suction effect on the air in the intake duct. This accelerated it. This prevents not only a drop in the degree of filling, but even one

An increase in the degree of filling, a charge. In high-performance and racing engines, strong valve overlaps at high speeds mean that fill levels of well over 1 can be achieved.

That's on engines that don't have actively controlled valves

"Valve overlap" method not applicable. But wherever it can be used, the process has clear limits.

For a given engine, there is an optimal valve overlap for each selected speed. If you increase the valve overlap beyond this value, the degree of filling deteriorates again at the selected speed. The higher the selected speed, the greater the optimal valve overlap. Very strong valve overlaps, such as must be selected for high-performance and racing engines, result in a high degree of filling at a high speed. However, they have poor filling levels and thus a low torque and a low output as well as a high specific consumption and a large pollutant and C0 "emissions in the middle and lower

Speed range.

In principle, with the valve overlap method, only a fraction of the total kinetic energy of the exhaust gases can be used to increase the degree of filling. Because before the intake valves open, a large part of the exhaust gases have already flowed out of the cylinder and can no longer suck in anything. Furthermore, only the one facing the intake valve exercises small part of the exhaust gases and in the final phase of the outlet the inertia of the exhaust gases creates a suction effect.

Furthermore, the shape of the combustion chamber, which must be designed primarily from other points of view, is anything but optimal with regard to achieving a high suction effect.

The invention has for its object to use the exhaust gas energy to increase the degree of filling outside of the combustion chamber, which is unsuitable for this purpose, with its poor suction efficiency.

This object is achieved by a device with the features of claim 1.

In the solution according to the invention, the entire and not just a small part of the exhaust gas energy is used to increase the degree of filling. The suction effect is generated in a technical device optimized for this and not in the combustion chamber with its poor suction efficiency, which is not very suitable for this. In four-stroke engines, it is possible to reduce the valve overlap to an almost vanishing remainder, so that torque and power in the lower and middle speed range, and thus the elasticity, in particular in the case of high-performance and racing engines, greatly increases and additionally increases the supercharging effect Effect how can be achieved by a variable valve control. It is also possible to make fresh gas acceleration possible by means of exhaust gas energy without a supercharger in those types of engines, such as two-stroke or rotary piston engines, in which this did not previously seem possible.

According to the invention, the kinetic energy of the exhaust gases is immediately opened the exhaust valves on and also used with closed intake valves. The suction time is longer and the suction power is considerably higher than with conventional suction motors.

According to the invention, a bypass duct is provided which bridges the inlet duct and the outlet duct of the same combustion chamber or different combustion chambers in the immediate vicinity of the inlet and outlet opening (in the case of internal combustion engines with valves of the inlet and outlet valves). H. connects with each other, and short-circuits past the combustion chamber. The connection of the bypass channel with the outlet channel is as

Exhaust jet pump trained. The exhaust gases flowing out of the combustion chamber at high speed exert a very strong suction effect on the inlet channel through this exhaust gas jet pump via the bypass channel. From experience gained in engines with forced air cooling using an exhaust gas jet pump, it is known that the exhaust gases can suck in an amount of air that is up to 15 times their own mass via an exhaust gas jet pump. Due to this great suction effect, the total amount of air in the inlet duct is very quickly pre-accelerated. When the inlet opening or the inlet valve or the inlet valves is opened, the bypass channel is closed synchronously by a bypass check valve, which is preferably arranged directly at the beginning of the bypass channel at its connection point with the inlet channel. The air column flowing at high speed in the intake port now presses all of its kinetic energy into the cylinder via the open intake opening (intake valve). This achieves a high charging effect. This effect can be increased by enlarging the cross sections of the inlet duct and the bypass duct.

Large valve overlaps are no longer necessary. The valve overlap can indicate an almost vanishing residue, which is used to flush the Combustion chamber is needed to be reduced.

With a four-stroke engine or with any other engine type with suitable spatial guidance of the bypass duct, there is the positive side effect of forced cooling of the cylinder head, so that the effort of the basic cooling system can be considerably reduced.

In the entire range from idling to maximum speed, a strong increase in the degree of filling, i.e. a strong charging effect, is achieved, although the engine is a naturally aspirated engine. The invention thus causes a considerable increase in torque and power over the entire available speed range. Maximum torque and maximum power are considerably higher.

The so-called transient behavior of the engine is superior to all other methods of increasing the degree of filling, including mechanical compressors. The engine reacts particularly spontaneously to very rapid changes in the load state. There is no comparable effect to the "turbo lag".

The additional space requirement of a construction according to the invention and the increase in weight are relatively small. The power density and power to weight ratio of the engine are extremely favorable.

The development effort required is very low and, for example in a four-stroke engine, relates only to the cylinder head. In a special embodiment, the device can also be arranged essentially outside the cylinder head, which has an even more favorable effect. The invention makes it possible for the first time to use the kinetic energy of the exhaust gases to accelerate the intake air even in the case of such types of clocked internal combustion engines that do not have actively controlled valves.

A particularly important advantage of the invention when applied to four-stroke engines is that the overlap of the valve timing can be reduced to a vanishing remainder even in the case of high-performance and racing engines. The serious disadvantages of large valve overlaps in the lower and medium speed range are completely eliminated. As an additional effect, the invention therefore has the same effect as fully variable valve control times. This has a further significant increase in torque and power in the lower and middle speed range, i. H. a large increase in engine elasticity, resulting.

Since the fresh gas is pre-accelerated by the suction effect of the exhaust gases and does not have to be sucked in by the piston, the piston does not have to do any pumping work. Not only are pump losses avoided, but the fresh gases flowing into the cylinder with great energy still give power to the pistons.

With four-stroke engines and with all other engine types with a suitably arranged bypass channel, there is a very effective forced cooling, e.g. B. the thermally highly loaded cylinder head. As a result, the basic cooling system can be designed significantly smaller. Primary coolant (water) is saved and thus weight. Furthermore, the performance of the primary coolant pump can be designed to be lower. This increases the engine's net output. Furthermore, the cooler can be dimensioned correspondingly smaller, which in turn saves weight and costs. Because of the smaller cooler and the much lower heat dissipation via the base Cooling system, the internal flow of a vehicle can be made smaller. The air resistance is reduced.

A motor provided with the device designed according to the invention has a higher overall efficiency and a significantly lower specific consumption than a conventional naturally aspirated motor because of the use of the exhaust gas energy. Consequently, the C0 _? - Lower emissions and emission of pollutants.

The embodiment of the invention in which the bypass duct connects the inlet duct and outlet duct of the same combustion chamber to one another is preferred because of its constructive simplicity.

Particularly good results are obtained with the device designed according to the invention if the opening time of the exhaust valve is shifted towards late compared to conventional engines. The size of the shift depends on the respective engine type and may need to be determined from engine type to engine type. In any case, there is a shift in the opening time, the opening being delayed or only taking place when the piston in the combustion cycle has moved closer to the bottom dead center than is the case with comparable conventional engines. For example, a shift up to 30 ° (crank angle) before bottom dead center.

Such a shift in the opening time of the exhaust valve maintains the pressure wave caused by the exhaust gases for as long as is necessary for optimal intake. The maximum of the speed of the exhaust gases is hereby delayed and the exhaust gas speed is increased, whereby the ^• Frischgasansaugeffekt is improved with the support of the bypass channel.

As already mentioned, the shaping of the bypass duct is preferably carried out in such a way that the cooling tasks of the air flowing through are taken into account, in particular the spark plug or the spark plugs as well as the exhaust valves being cooled as effectively as possible by the air flowing through.

The control of the opening and closing movements of the bypass shut-off valve are coordinated according to the invention with the movements of the inlet valve and the outlet valve or valves. The bypass shut-off valve is always closed when the inlet valves are open. The bypass shut-off valve is only open when the inlet valves are closed. When the inlet valves are opened, the check valve thus closes synchronously. The check valve opens at the earliest when the inlet valves close or at the latest at a time to be determined by the designer after the outlet valves have opened. With respect to the exhaust valve or valves, the check valve should open at the latest when the exhaust valve or valves open.

In the case of a naturally aspirated engine that does not operate according to the four-stroke principle, for example in the case of a two-stroke or rotary piston suction engine, etc., the check valve is preferably designed as a rotary slide valve, which is preferably driven directly by the crankshaft.

In the case of a four-stroke engine, the bypass shut-off valve is preferably a flat slide that can be moved up and down in a guide. The shut-off valve is in the lower position of the flat slide valve closed. It is open when the flat slide is in the upper position. At the upper end of this flat slide valve stem is attached so that it lies in the plane of the slide. This shaft is preferably moved downwards, like that of a normal engine valve, by a cam disc or a cam attached to the camshaft and is moved upwards by one or more springs or "desmodromically" by a further cam disc attached to the camshaft. The shape of the cam discs or cams of the inlet valves, the check valve and the outlet valves is such that the control of the check valve described above can be carried out.

In order to achieve an optimal effect of the exhaust gas jet pump, the end cross-sectional area of the first channel section of the outlet channel or the end cross-sectional area of the bypass channel can be circular, depending on which of the two alternatives is used for the configuration of the exhaust gas jet pump. However, silT preferably have shapes with a larger ratio of circumference / area to the area of an annular sector of more than 270 ° with rounded ends.

In the embodiment according to the invention, in which a plurality of bypass secondary ducts are provided, these are guided and designed in a flow-dynamic manner in such a way that they mainly serve to cool specific areas of the cylinder head, the cylinder or other engine parts.

In engines in which the intake and exhaust valve are on the same cylinder side, the device or the bypass channel is preferably arranged outside the cylinder head, so that the cylinder head does not have to be redesigned. The invention is explained below using an exemplary embodiment in conjunction with the drawing. The single figure shows schematically a combustion chamber equipped with a device designed according to the invention in four phases.

The figure shows a combustion chamber 1 of a cylinder of an engine, this cylinder being provided with an intake valve 6 and an exhaust valve 7. It is understood that the invention is not limited to such an embodiment and other motors can also be used. The cylinder shown here can also be provided with multiple intake and multiple exhaust valves. Between the inlet duct 2 leading to the combustion chamber 1 and the outlet duct 3 leading away from the combustion chamber 1 there is a bypass duct 4 connecting them. The bypass channel is arranged in the immediate vicinity of the corresponding cylinder inlet and outlet opening. At the boundary point between the inlet channel 2 and the bypass channel 4 there is a shut-off valve for the bypass channel, which is opened and closed as a function of the inlet valve 6 and outlet valve 7. The connection point between the bypass duct 4 and the outlet duct 3 is designed as an exhaust gas jet pump (shown schematically at 10). For this purpose, the outlet channel has a first section 8 and a second wider section 9. The first section 8 projects at the transition point between the two sections as a suction part of the exhaust gas jet pump into the bypass channel 4-second section of the outlet channel 9. The bypass duct 4 merges smoothly into the second section 9 of the outlet duct. The figure shows the combustion chamber provided with the device according to the invention in four phases. In phase 1, the outlet valve 7 is open and the inlet valve 6 is closed. The bypass check valve 5 is also open. That from the first Section 8 of the exhaust duct 3 exhaust gas escaping at high speed sucks in air via the exhaust jet pump 10 via the bypass duct 4 from the inlet duct 2 (see the arrows shown). This air is strongly accelerated.

In the following phase 2 there is only a short valve overlap. The inlet valve 6 and the outlet valve 7 are open. The bypass shut-off valve 5 is closed and the combustion chamber 1 is flushed.

In the subsequent phase 3, the outlet valve 7 is closed and the inlet valve 6 is open. The bypass shutoff valve 5 is closed. The air brought to high speed in phase 1 is forced into the combustion chamber 1 due to its inertia. A high charging effect is achieved.

In the following phase 4 all valves are closed. The compression and work cycle takes place.

Claims

1. Device for increasing the fresh gas filling during the intake or loading cycle of a clocked internal combustion engine with internal combustion with a bypass channel (4), the same as the inlet channel (2) of a combustion chamber (1) with the outlet channel (3) or one connects other combustion chamber in the immediate vicinity of the inlet and outlet openings outside the combustion chamber (1), and a bypass channel (4) which closes synchronously with the opening of the inlet opening and which opens at the earliest when the inlet opening closes the blocking valve (5) for the bypass Channel (4), the connection of the bypass channel (4) to the outlet channel (3) being designed as an exhaust gas jet pump (10).

2. Device according to claim 1, characterized in that the bypass channel (4) connects the inlet and outlet channel (2, 3) of the same combustion chamber (1) with each other.

3. Apparatus according to claim 1 or 2, characterized in that the opening time of the exhaust valve (7) or the exhaust valves of the combustion chamber (1) is shifted towards a conventional engine in the late direction.

4. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the bypass channel (4) is arranged in the immediate vicinity of the one or more inlet and outlet valves (6, 7).

5. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the check valve (5) opens at the latest when the or the outlet valves (7) open.

6. Device according to one of the preceding claims, characterized in that the bypass channel (4) at no point has a smaller cross section than the smallest cross section of the entire inlet channel (2) at full load.

7. Device according to one of the preceding claims, characterized in that the bypass channel (4) is optimized in its shape to the lowest flow resistance.

8. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the check valve (5) is arranged directly at the boundary point between the inlet channel (2) and bypass channel (4).

9. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the check valve (5) is designed as a slide valve.

10. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the check valve (5) is designed as a rotary slide valve.

11. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the check valve (5) via the camshaft or directly via the crankshaft is controlled.

12. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the outlet channel (3) in the flow direction has two successive, flowing into each other sections (8, 9), the first section (8) at the transition point as a suction Part of the exhaust gas jet pump (10) protrudes into the transition bypass channel (4) - second section (9) of the exhaust channel (3).

13. The device according to one of claims 1 to 11, characterized in that the outlet channel is undivided and the bypass channel protrudes as part of the exhaust gas pump to be suctioned into the outlet channel.

14. Device according to one of the preceding claims, characterized gekenn¬ characterized in that neither the outlet channel (3) nor the bypass channel (4) have a cross-sectional narrowing over their entire course.

15. The apparatus according to claim 12 or 13, characterized in that the end cross-sectional area of the first section (8) of the outlet channel and / or the end cross-sectional area of the bypass channel (4) are circular or have shapes with a larger ratio of circumference / area.

16. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the outlet channel (3) from the point of connection with the bypass channel (4) has a larger cross-section corresponding to the volume of the exhaust gas plus the volume of the air sucked in via the bypass channel than in its course up to this point.

17. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the length of the inlet channel is variable, in particular continuously variable.

18. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the bypass channel in a cylinder head provided with four or five valves along the outside of the combustion chamber wall on both sides by the centrally located spark plug or by a central web, in the course of which the spark plug is longitudinally divided into two subchannels.

19. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the shut-off valve is positioned between two inlet valves, the valve stem of the shut-off valve viewed from the camshaft is inclined downward more towards the outlet side than the parallel valve stems of the inlet valves, so that the lower edge of the valve stem of the check valve is arranged somewhat offset inwards towards the outlet side with respect to the inlet valves.

20. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the arrangement of the control cam for the two Einlaß¬ valves and the control cam for the check valve on an overhead camshaft is identical to the arrangement of the three control cams for the three intake valves in a five-valve -Cylinder head, with the middle of the three cams being the cams for the check valve.

21. Device according to one of the preceding claims, characterized gekenn¬ characterized in that the bypass channel has a plurality of bypass secondary channels that branch from the bypass channel at locations that in As seen in the direction of flow, lie behind the shut-off valve, and reunite with the bypass duct at points which are in front of the exhaust gas jet pump as seen in the direction of flow.

22. Device according to one of claims 1-17 or 21, characterized gekenn¬ characterized in that the bypass channel is arranged outside of the cylinder head in engines in which the intake and exhaust valve is on the same cylinder side.