DE2823448A1 - IC engine with stepped piston supercharger - which is ported and has check valves to obtain one-way flow - Google Patents

Abstract

Stepped piston has a first portion working in the conventional way as the movable wall of the combustion chamber. A stepped, or enlarged dia., portion operates in an adjacent, axially aligned, bore of the cylinder. The stepped portion of the piston is ported and check valves are provided at the ports which permit a one way flow of fuel-air mixture from the engine crankcase into the compressor portion of the engine comprising the stepped portion of the piston and the bore in which it is working. This arrangement provides two intake and two compression strokes of the compressor per four cycle combustion cycle. The mixture which enters the compressor on the down-stroke of the piston is trapped by the check valves, compressed on the up stroke and delivered into a bypass and accumulator manifold connected to the intake valve for the main cylinder.

Description

5324

Γ PATENT LAWYERS ~~ l

DR.-ING. R. DÖRING DIPL.-PHYS. DR. J. FRICKE

BRAUNSCHWEIG MUNICH

DANA Corporation Toledo Ohio / USA

"Four-stroke internal combustion engine"

The invention relates to a four-stroke internal combustion engine with the features of the preamble of claim 1.

The trend in the design of internal combustion engines is constantly towards higher performance with a given piston stroke, a given one To achieve size and given weight. In addition, fuel efficiency is also a factor in many applications important point of view. It is well known to those skilled in the art that a typical two-stroke engine produces significantly more horsepower per volume shift at a given speed delivers than any four-stroke engine with natural intake that, however such a machine shows a significantly poorer efficiency. Turbocharged four-stroke machines, on the other hand, form a kind of Compromise by giving more force per unit weight than usual

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Four-stroke machines and better fuel economy than Deliver two-stroke machines. However, charging devices are usually expensive and are therefore essentially only used in Racing or sports car applied.

It is the object of the invention to provide a four-stroke internal combustion engine to further develop with the features of the preamble of claim 1, that with this machine, too, a comparatively better fuel economy and a higher output per unit weight can be achieved.

This task is with the features of the characterizing part of the claim 1 solved.

In the new four-stroke internal combustion engine, a stepped piston is used which has a first section which in the usual way, the movable wall of the combustion chamber, that is, forms the working piston. One increasing in diameter Piston section works in an adjacent and axially in Aligned bore of the cylinder housing. The widened Piston section is provided with openings and with check valves. These allow a flow in only one at a time Direction of a fuel-air mixture from the crankcase of the engine into the compression chamber of the engine, which is limited by the widened portion of the piston and the bore in which it works. This arrangement sees two inlet and two compression strokes of the compressor

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piston on each entire cycle of the four-stroke engine. the Mixture entering the compression chamber on the downward stroke of the graduated piston is passed through the Check valves captured and compressed on the upstroke and transferred to a bypass or collector supplied to the inlet valve of the master cylinder or the combustion chamber leads. The compression device according to the invention is thus effective to charge two at a time Deliver volumes per duty cycle to the bypass manifold. This arrangement thus serves as a charging device and provides a simply built four-stroke internal combustion engine with high horsepower output for any given unit weight or Volume shift.

Advantageously, the volumes of compression chamber and Combustion chamber essentially the same size.

In order to keep the dimensions of the machine small, it is advisable to if the working piston has a circular cross-section, the compression piston has an elongated or long-oval cross-section have, the smallest cross-sectional dimension essentially corresponding to the diameter of the working piston.

The fresh air or the mixture of fresh air and fuel is advantageously supplied to the compression chamber in that the compression piston itself has an inlet check valve which opens into the crankcase and

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opens into the compression chamber, the mixture or the Fresh air is supplied through the crankcase.

The invention is explained below with reference to schematic drawings explained in more detail using several exemplary embodiments.

Show it:

Fig. 1 to 4 each have the same side views in vertical

Section of a selected cylinder, the associated working piston at the inlet, the Compression, power and exhaust strokes are shown;

Fig. 5 shows a cross section of the machine in detail

1 to 4 in a modified but preferred embodiment;

Figure 6 is a timing diagram showing the operation of the machine of Figures 1 to 4;

7 shows a partial view of a preferred arrangement of piston and cylinder of a multi-cylinder machine according to the present invention;

8 shows a side view of the piston and the cylinder according to FIG. 7, partly in section;

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FIG. 9 is an isometric view of a piston according to FIG.

and 8

as
Fig. 10 shows a detail for a preferred sealing of the

Compression chamber.

In the preferred embodiment of the invention, each comprises Cylinders, only one of which is shown in Figures 1 to 4, a piston 10 with a widened or stepped Section 12 at the bottom. The piston is arranged to have a crankshaft 12 via the crank arm 16 and the crank pin 17 drives in the usual way. The upper region or working piston 10 is within a combustion chamber cylinder 18 reciprocated and includes grooves for receiving upper and lower piston seal rings 19 and 19a. The annular extended Section or compression piston 12 is carried by working piston section 10 and is preferably integral therewith educated. The compression piston works in the enlarged cylinder area which is delimited by the walls 20. The compression piston includes openings or passages for the supply of a fuel-air mixture from the crankcase 23 of the machine out into the compression chamber, which is through the cylinder walls 20 and the compression piston section 22 and the annular shoulder 25 at the lower end of the combustion chamber wall 18 is determined. Channels 26, which can be closed by check valves 27, go through the shoulder region 25. At least there are £ because there is a passage 26 and a non-return valve 27

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seen. However, several such units are preferably approximate arranged uniformly around the shoulder 25, depending on the size and the working characteristics of the machine concerned.

The check valves 27 open into an annular receiving line 28, which is provided above the shoulder 25 in the cylinder housing and in open connection with a manifold 29 stands. The other end of the manifold 29 can periodically connect to the combustion chamber of the engine via the intake valve 30 can be associated. The valve 30 can be configured in various ways. For many applications it is preferred to design the valve as a rotating valve of the type shown in order to take advantage of this type of valve can. However, conventional poppet valves or other valve types can also be used, depending on the application and preferred Characteristics depends. The discharge or outlet from the cylinder is also determined by the rotating valve 30, as indicated in FIG. 4 in a section of the ejection cycle which is explained in more detail below.

However
Combustion air, normally / already in the form of an air fuel mixture, is fed in from a carburetor or the like (not shown) via a line 32. If necessary and also preferably, check valves 3k are provided in order to prevent a backflow to the carburetor. Fuel injectors (not shown) can also be used to inject fuel into the fuel

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Inject the chamber in a known manner, as is the case, for example, with diesel engines of the Pail.

A preferred arrangement and design for the part of the machine block, which defines the collection chamber 28 is in detail shown in fig. The combustion chamber cylinder is as Part of the machine block provided and carried by the outer wall 36 of the machine block by the shoulder 25. One after Annular chamber 38, open at the top, is formed in this way. Several passages 26 in the shoulder 25 are provided with a check valve 27, which is fitted into the bottom of the recess 28 in the form of an annular disc. One special preferred embodiment of the check valve 27 comprises an upper disk 27a made of rubber or the like. and a lower disk 27b made of a thin spring material of a beryllium alloy .

The inner circumferential surface of the disk 27 is on the shoulder 25 by the sleeve portion 40, in particular by the cylindrical Clamped end 41 of reduced diameter, which Section slides over the cylinder wall 18 engages. The section 41 ends in the upper area in a radial shoulder 42, which extends to the section 43 of larger diameter. Of the cylindrical portion 43 engages with a sliding fit in the outer wall 36 and lies sealingly against the cylinder head gasket 46 of the machine head 48 containing the valve.

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Since the sleeve 40 is sealed at each end, it shares the Recess 38 in two separate chambers, the collecting chamber 28 and the annular chamber 50 which is connected to a source of circulating cooling water is connected.

Fig. 6 illustrates the operation of the machine during a complete work cycle. To explain the operation of the compression device, the operation of the machine from the top dead center to the bottom dead center is represented by a range of 180 ° on the time diagram, in contrast to a representation of 360 °. A full combustion cycle comprises a Maschinenansaughub, generally takes place in the first quadrant I the timing chart, a compression stroke (Quadrant H) ₃ a working stroke (Quadrant III) and an exhaust stroke (Quadrant IV). The particularly preferred embodiment of the invention associated with the timing chart of Figure 6 is a high performance machine with substantial valve overlap. In particular, the inlet valve k2 opens before the top dead center and closes 70 ° behind the bottom dead center, while the exhaust valve opens 64 ° before the bottom dead center of the working stroke and only closes 36 ° behind the top dead center of the exhaust stroke.

The operation of the compression device according to the invention is also shown in FIG. The check valves for the compressor are only controlled by the prevailing gas pressures, inertial forces and the piston movement.

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This means that they essentially open and close
in the upper and lower dead center positions of the piston.

It can be seen that the compression section of the engine delivers two charges of combustible mixture to the combustion chamber on each combustion stroke. The mixture of fuel and gas or air in crankcase 23 is typically fed from a carburetor (not shown) through passage 32 and enters the crankcase through check valve Jk under substantially atmospheric pressure, though
as mentioned above, the fuel can also be injected separately into the combustion chamber.

It is believed that an atmospheric pressure mixture of fuel and air is supplied via line 32 to the crankcase. The compressor section is initially set up with a
Mixture filled by atmospheric pressure. Two "charges" of the compressor device are assigned to the combustion chamber for each intake stroke of the engine. Assuming that there is no valve overlap, the theoretical boost pressure results as follows:

P _E = 2 χ ^V E χ atmospheric pressure (lM.7 PSIA)

Here, P _{E is} the pressure in the engine's combustion chamber, V "is the volume of the engine's combustion chamber, and V _n das
Volume in the compression device.

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It can be seen that charging occurs with any machine geometry, provided that the volume of the compression device is greater than half the volume of the combustion chamber. Typically, a lower limit for practical machine design is a compression volume that is approximately three quarters of the volume of the combustion chamber.

In the preferred embodiment as shown, the volumes of the combustion chamber and the compression device are practically the same. This leads to the assumption that there is no valve overlap, to a theoretical boost pressure of about double atmospheric pressure (29 PSIA). In the In practice, due to the valve timing control according to FIG. 6, a boost pressure is achieved which is etnas lower than the theoretical one Pressure is. But even with the relatively large valve overlap indicated by section B in FIG. 6, one obtains a substantial charge.

Figures 7 to 9 show a preferred multi-cylinder arrangement in a schematic embodiment. To the size and weight of the To downsize the engine, it is preferred to use the minimum spacing between adjacent combustion cylinders. To this The purpose is to have the compressor piston in axial alignment with the cylinders of an extent equal to approximately the extent of the Piston diameter and extends across the machine. This means that, according to FIG. 7, adjacent pistons are axially adjacent to one another can be arranged without the need for a

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provide additional spacing for receiving the enlarged portion or compression piston portion of the piston. As FIG. 8 shows, a collection chamber 28a is preferably provided above the widened piston section. Distribution lines of a suitable type, which can be adapted to the overall machine geometry, are provided around the collecting chambers 28a and to connect the combustion chambers. In some applications it may be preferred in the cylindrical body of the main portion of the piston to provide a recess immediately above the stepped portion 17a, so that only a single collection section 28a can be used.

Figure 10 illustrates a preferred seal for the compressor pistons 12 or 12a. A circumferential groove 50 is provided in the piston 12 and has a stepped portion 51 of reduced radial depth. An O-ring 52 made of suitable rubber or rubber-like material is inserted into the groove 50 and provides a resilient preload for a sealing element 53, which consists of polytetrafluoroethylene or the like in a continuous ribbon form of rectangular cross-section.

Reference is again made to FIGS. 1 to 4 to describe the mode of operation. In Fig. 1 the piston is in his lowest position shown immediately before the start of the compression stroke. During the previous 180 ° of the crankshaft revolution the piston had moved down from the top dead center, with the check valve 24

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opens to air or a fuel-air mixture from the To let the crankcase into the compressor. At the same time, the inlet portion of the rotary valve 30 was opened and the charge previously contained in the manifold 29 is drawn into the cylinder 18. In Fig. 2, the crankshaft is 90 ° from the Rotated position according to FIG. 1. The valves 24 and 30 are closed and the enlarged portion 12 of the piston 10 is located compressed to one on the first of its two compression strokes during the engine's combustion cycle To deliver the mixture of fuel and air into the collecting or distribution channel 29 through the valve 27 which is now open. In Fig. the charge in the master cylinder has been ignited and the piston begins its downward power stroke, see the valve 24 opens again to allow a fresh charge of air or air-fuel mixture into the compressor. Fig. 4 gives the piston in the top dead center position again, namely on End of the exhaust stroke of the overall cycle, which coincides with the completion of the second compression stroke. Thus it can be seen that two compression strokes of the compression piston per combustion cycle the machine. There is no critical relationship between the volumes of the compressor and the combustion chamber the machine. The relative volumes can be varied as required to achieve the desired degree of charging to reach. The 1: 1 ratio of the volumes and the resulting 2: 1 compression ratio are preferred. The volume of the manifold primarily affects the operation as it determines the time it takes for the

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same constant working pressure is achieved. If the distribution volume is relatively small, the same working pressures are achieved with fewer strokes than with a distribution volume which is, for example, much larger than the volume of the compression cylinder. The end result, however, is predetermined for each Machine the same by always achieving the same pressure, regardless of the size of the distribution volume or the machine speed. It is preferred that the manifold volume be of the same order of magnitude as that the compressor and the combustion chamber.

Different variations can be made. As mentioned briefly above, the charger according to the present invention are also used in connection with fuel injection machines, namely gasoline or diesel engines. Instead of a rotating valve, it is also possible to use any one to use another suitable valve. Similarly, the timing (Fig. 6), the size of the charge and others Features of the overall machine vary from the given values without thereby departing from the scope of the invention will.

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Claims (6)

5324 ι DATCMTA Μ \ Α / Λ I TC X IJ X ^ J /> AH PATENT LAWYERS DR.-ING. R. DÖRING DIPL.-PHYS. DR. J. FRICKE BR ΑμΗβ CHWEIG. ^? MUNICH Expectations (l] Four-stroke internal combustion engine in which each internal combustion chamber is limited by a cylinder and a reciprocating working piston in this, a crankcase and a valve device for controlling the discharge, suction, compression and work cycles is provided are, characterized in that a compression cylinder (20) and a sealing in this movable compression piston supported by the working piston (10) (1 £) are provided, which together delimit a compression chamber, which depends on the direction of movement of the two pistons alternately with fresh air and a compressed air collection device (28,29) is connectable, which in turn with the combustion chamber (18) during the intake stroke of the working piston (10) is connectable. 2. Internal combustion engine according to claim 1, characterized in that the effective volume of the compression device is greater than half the volume of the combustion chamber. L J 909849/0103 ORIGINAL INSPECTED 3. Internal combustion engine according to claim 2, characterized in that that the volumes of compression chamber and combustion chamber are essentially the same. 4. Internal combustion engine according to one or more of claims 1 to 3, in which the working piston is circular Having cross-section, characterized in that that the compression piston (12) has an elongated cross section with a smallest dimension essentially has the same diameter as the working piston (10). 5. Internal combustion engine according to one or more of claims 1 to 4, characterized in that that the Konipressionskolben (12) has an inlet check valve (22,24) which opens into the crankcase and in the compression chamber opens. 6. Internal combustion engine according to one or more of the claims 1 to 5, characterized in that two compression volumes of the compression piston (12) can be fed to the combustion chamber (18) on each intake stroke of the working piston (10). 9 349/0103