EP0637677B1 - Four stroke internal combustion engine - Google Patents

Description

The present invention relates to a four-stroke internal combustion engine according to the preamble of patent claim 1.

As is well known, four-stroke internal combustion engines of the reciprocating type have reached a high level of development. Nevertheless, they have the fundamental disadvantage that the reciprocating stroke movement of the piston must be transmitted to the drive shaft via a crank mechanism. The crank mechanism makes the reciprocating engine complex, heavy and space-consuming, which is ultimately reflected in the use of materials and fuel.

Four-stroke internal combustion engines of the rotary or rotary piston type do not require a crank mechanism, since the rotary movement of the rotary piston can be converted directly into shaft power. However, the success of the rotary piston engine in practice is due to other disadvantages such as Sealing problems, triple charge changes with high fuel consumption during a piston revolution, etc. comparatively low.

The present invention has for its object to provide a four-stroke internal combustion engine working on a novel principle, which is characterized by design simplicity, low weight and low fuel consumption.

To solve this problem, a four-stroke internal combustion engine of the type specified in the preamble of claim 1 is characterized according to the invention in that the piston is mounted in the cylinder axially and rotatably and between the piston and the cylinder a wavy, positive guidance is provided, which impresses the piston with a rotation of 360 ° four axial strokes for the four work cycles, that the cylinder and the piston each have a combustion chamber half in their peripheral walls adjacent to their adjacent end faces, which at the time of ignition of the fuel gas supplement a combustion chamber, so that fuel gas expanding in the combustion chamber exerts a torque on the piston, and that a coaxial shaft shaft is provided on the piston for deriving the rotary movement carried out by the piston.

From DE-PS 121 720 and DE-PS 725 885, engines in the form of steam engines are already known, in which the piston simultaneously performs a rotating and lifting movement due to a positive guidance. In these engines, however, the positive guidance is designed so that the piston performs only two stroke movements at a rotation of 360 °. For this reason and for other reasons, the machines shown there are therefore not suitable as a four-stroke internal combustion engine.

In the four-stroke internal combustion engine designed according to DE-A-4027533, the piston carries out four stroke movements for the four working cycles during a revolution of 360 °, suctioning - compressing - expanding (working) - expelling. The shaft power generated by the motor can be taken directly from the rotating piston. In the engine designed according to the invention, the combustion chamber halves formed in the peripheral walls of the cylinder and piston and complementing one combustion chamber ensure that the expanding fuel gas immediately exerts a torque on the circumference of the piston during the expansion work cycle. The rotational forces exerted on the piston are therefore considerably greater than the axial forces exerted on the piston.

The four-stroke internal combustion engine designed according to the invention combines to a certain extent the advantages of a reciprocating piston engine and a rotary piston engine. Since a crank mechanism is not required, it is simple in construction and comparatively light in weight. Since the forces exerted by the expanding fuel gas act primarily in the circumferential direction and act on the outer circumference of the piston, the engine operates with high efficiency, which is reflected in a correspondingly low fuel consumption. This is promoted by a good swirling of the fuel gas in the displacement, which is brought about primarily by the rotary movement of the piston. Because of the simple construction, the susceptibility to faults is low, so that the motor has a long service life.

In a further embodiment of the invention it is provided that the shaft shaft provided on the piston to compensate for the lifting movement and to transmit the rotary movement of the piston is mounted in an axially movable and rotationally fixed manner in a drive shaft which is rotatably and axially fixed in the cylinder. The drive shaft thus immediately receives the torque generated by the engine.

The valve device preferably consists of a valve flange with a valve slot penetrating the valve flange, which is rotatably mounted in the end wall of the cylinder and rotates with the piston, so that the valve flange with the valve slot opens and closes the inlet and outlet opening in a timely manner. This further simplifies the internal combustion engine, since no separate intake and exhaust valves with valve control are required.

In a further embodiment of the invention it is provided that a further displacement is formed between the piston and the cylinder on the rear side facing away from the working side, each of which has a return line with the inlet channel and the The outlet duct is connected in such a way that part of the exhaust gas (for example a third to a quarter of the quantity of exhaust gas) is returned from the outlet duct to the rear displacement and from there via the inlet duct together with fresh fuel gas to the working displacement. The hot exhaust gas ensures rapid heating of the fuel gas and the entire engine to the operating temperature, which is particularly advantageous particularly in operating conditions with a heat deficit, such as during a cold start, since this ensures that the catalytic converter functions correctly immediately after starting. The amount of pollutants in the exhaust gas is considerably reduced by the exhaust gas recirculation in its own cylinder. In addition, the recirculated hot exhaust gas ensures good swirling of fuel and combustion air.

Further advantageous embodiments of the invention emerge from the subclaims.

The four-stroke internal combustion engine designed according to the invention can be operated both as a gasoline engine and as a diesel engine. The preferred field of application of the invention is the motor vehicle engine, but is not limited to this.

Fig. 1

einen schematischen Längsschnitt durch eine Zylinder-Kolben-Anordnung eines Viertakt-Verbrennungsmotors;

Fig. 2

eine Draufsicht auf die Zylinder-Kolben-Anordnung der Fig. 1;

Fig. 3 und 3a

Schnittansichten in Blickrichtung der Pfeile III in Fig. 1 mit zwei um 180° gegeneinander versetzten Stellungen des gestrichelt angedeuteten Kolbens;

Fig. 4

eine Ansicht in Blickrichtung der Pfeile IV in Fig. 1;

Fig. 5

eine in Umfangsrichtung abgewickelte Ansicht der Umfangsfläche des Kolbens in verkleinertem Maßstab;

Fig. 6

eine perspektivische Explosionsdarstellung der Ventileinrichtung für die Zylinder-Kolben-Anordnung der vorhergehenden Figuren;

Fig. 7

eine Draufsicht auf den Ventilflansch der Ventileinrichtung in Fig. 6.

A preferred embodiment of the invention is explained in more detail with reference to the drawings. Show it:

Fig. 1

a schematic longitudinal section through a cylinder-piston arrangement of a four-stroke internal combustion engine;

Fig. 2

a plan view of the cylinder-piston arrangement of Fig. 1;

3 and 3a

Sectional views in the direction of arrows III in Figure 1 with two positions of the piston indicated by dashed lines offset by 180 °;

Fig. 4

a view in the direction of arrows IV in Fig. 1;

Fig. 5

a circumferentially developed view of the circumferential surface of the piston on a reduced scale;

Fig. 6

a perspective exploded view of the valve device for the cylinder-piston arrangement of the previous figures;

Fig. 7

6 shows a plan view of the valve flange of the valve device in FIG. 6.

In the drawings, a cylinder-piston arrangement of a four-stroke internal combustion engine operating according to the Otto process is shown. The components of the internal combustion engine, not shown in the drawings, such as e.g. Fuel-air mixture preparation (carburetor or injection), electronic control, lubrication, ignition etc. can be of conventional design. Therefore, since they are not necessary for an understanding of the invention, they are not described.

The cylinder-piston arrangement shown in Fig. 1 is formed by a housing in the form of a cylinder 2, which consists of a cylindrical peripheral wall 4 and two end walls 6a and 6b. The end walls 6a, 6b are fixedly and sealingly connected to the peripheral wall in order to form a cylindrical space in the interior of the cylinder.

In this cylindrical space, a cylindrical piston 10 is slidably supported by means of piston rings 12, so that the cylindrical interior is divided into a displacement 8 on the left side in FIG. 1 (working side) and a displacement 9 on the right side (return side) becomes.

The piston-cylinder arrangement shown in Fig. 1 is symmetrical in some respects with respect to a central plane III-III educated. The parts located opposite one another on the working and return sides, which correspond, have therefore been identified with the same reference numerals with the addition of the letters a and b.

The piston 10 is provided on its opposite end faces with a coaxial shaft shaft 14a, 14b, which is connected to a drive shaft 16a or 16b in a rotationally fixed but axially displaceable manner. For this purpose, the shaft shafts 14a, 14b are designed as hexagonal or octagonal shafts, which extend into correspondingly designed inner hexagonal or octagonal guides of the drive shafts 16a, 16b. The drive shafts 16a, 16b are in turn rotatably supported by bearings 18a, 18b in the end wall 6a and 6b and are axially immovable.

Because of this arrangement, the piston 10 can perform both a rotational movement and an axially reciprocating stroke movement. As indicated in Fig. 1, the piston 10 has a comparatively large diameter. The axial length of the cylindrical interior is approximately 50% greater than the axial length of the piston.

In order to impart a simultaneous rotating and lifting movement (winch movement) to the piston 10, a positive guide 20 is provided between the piston 10 and the peripheral wall 4. The positive guide 20 has a wave-shaped circumferential groove 22 formed in the circumference of the piston and having a semicircular cross section with four approximately semi-sinusoidal winding sections, cf. 5. In the circumferential wall 4 of the cylinder 2, two balls 24 are mounted at diametrically opposite locations with the aid of two screws 26, half of which engage in the groove 22 of the piston 10. The winding portions of the groove 22 are shaped so that the piston makes four strokes for the four in one revolution Work cycles suction - compressing - expanding (working) - ejecting, as will be explained.

On the working side (left side in the figure) of the cylinder-piston arrangement, a combustion chamber half 32 and 34 is formed in the peripheral wall 4 of the cylinder and in the peripheral wall of the piston 10, adjacent to the end face of the cylinder or piston supplement the position of the piston 10 indicated by dashed lines in FIG. 3a to form a combustion chamber 30. As can be seen in FIGS. 3, 3a, each of the combustion chamber halves 32, 34 has an approximately triangular outline in a plane perpendicular to the cylinder axis, the combustion chamber halves 32, 34 on their inner long sides and the combustion chamber half 34 also on their one axial end face to the working displacement 8 are open. An ignition device in the form of a spark plug 35 is assigned to the combustion chamber half 32 formed in the cylinder 2. The mode of operation of the combustion chamber 30 is explained in more detail below.

In the end wall 6a of the cylinder 2, an inlet channel 36 with an inlet opening 38 opening into the displacement 8 is formed for supplying fuel gas, cf. 3, 3a and 4. Furthermore, an outlet channel 40 is formed in the end wall 6a with an outlet opening 42 connected to the displacement 8 for discharging exhaust gas.

To open and close the inlet opening 38 and outlet opening 42, a valve device is provided, which in the exemplary embodiment shown is designed as a valve flange 48a provided on the drive shaft 16a with a valve slot 54a penetrating the valve flange 48a (cf. in particular FIGS. 1, 3, 3a and 6, 7). The valve flange 48a, which is rotatably mounted in a recess in the end wall 6a, performs the same rotary movement because of the drive connection between the drive shaft 16a and the piston 10 like the piston 10, so that the valve slot 54a alternately coincides with the inlet opening 38 and the outlet opening 42, in order to open and close the inlet opening 38 and the outlet opening 42 in accordance with the four work cycles of the four-stroke engine.

In order to avoid leakage losses between the valve flange 48a and the end wall 6a, a sealing washer 50a is axially slidably mounted in a recess of the valve flange 48a. The sealing disk 50a is provided with a valve slot 52a penetrating the sealing disk, the shape of which corresponds to the valve slot 54a and is slidably guided on an axial shoulder surrounding the valve slot 54a of the valve flange 48a, cf. 6 and 7. The sealing washer 50a is pressed against the end face of the end wall 6a by several (for example three) curved leaf springs 56a, which are supported on the valve flange 48a, so that the sealing washer 50a can perform its sealing function to avoid leakage losses.

The operation of the cylinder-piston arrangement described so far of the four-stroke internal combustion engine working according to the Otto process is as follows:

It is assumed that the piston 10 is just starting its suction stroke. At this point, the piston 10 assumes the angular position shown in FIG. 3, in which the valve slots 52a, 54a are just beginning to cover the inlet opening 38. At this time, the piston 10 assumes its left end position in FIG. 1, so that the volume of the displacement 8 - apart from the volume of the combustion chamber halves 32 and 34 - is zero. If the piston now makes a quarter turn clockwise (in FIG. 3), the piston 10 is simultaneously displaced into its right end position (FIG. 1) by the positive guide 20. This turns fuel gas out the inlet channel 36 is sucked into the displacement 8 through the now opened inlet opening 38.

The fuel gas can consist of a fuel-air mixture if the mixture is formed in a carburetor (not shown). However, it can also consist of pure air if the mixture is only formed in the displacement 8 by means of fuel injection (not shown).

Upon its further rotation by 90 °, the piston executes a lifting movement into its (in FIG. 1) left end position, as a result of which the fuel gas located in the displacement 8 and in the combustion chamber halves 32, 34 is compressed. At the end of the compression stroke, the piston 10 assumes the angular position indicated in dashed lines in FIG. 3a, in which the combustion chamber halves 32 and 34 complement each other to form the combustion chamber 30 and in which the maximum compression is achieved. At this point, essentially all of the fuel gas is in the combustion chamber 30 and is now ignited by the spark plug 35.

As shown in FIG. 3a, the combustion chamber 30 has an approximately rectangular shape, the combustion chamber half 34 of the piston 10 having a drive surface 34 'substantially perpendicular to the circumferential direction and the combustion chamber half 32 formed in the cylinder having a reaction surface 32' substantially parallel thereto. Due to this combustion chamber design, the expanding fuel gas exerts a rotating force on the piston 10, which acts on the outer circumference of the piston 10 and thus generates a correspondingly large torque.

The piston 10 is thus driven by the fuel gas in the direction of rotation, while at the same time exerting an expansion stroke (to the right in FIG. 1). The rotary movement of the piston 10 is directly on the drive shaft via the shaft 14a 16a transmit, which ensures a high efficiency of the internal combustion engine.

After a quarter of a turn, the piston has completed its work stroke (expansion stroke), whereupon the work cycle begins to expel the exhaust gas. During the exhaust stroke, the piston 10 is again moved to the left (in FIG. 1) by the positive guide 20, while the valve slots 52a, 54a sweep over the outlet opening 42. The exhaust gas is thus expelled from the piston 10 into the exhaust gas duct 40. At the end of the ejection stroke, the piston 10 again assumes the angular position indicated by the broken line in FIG. 3, in which the valve slots 52a, 54a are located between the outlet opening 42 and the inlet opening 38.

The piston 10 has thus carried out the four working cycles of suction - compression - working (expanding) - ejecting which are characteristic of a four-stroke engine, with each working cycle corresponding to a piston rotation by 90 ° and an axial stroke movement. During a work cycle with the four work cycles, the piston 10 thus makes a rotation through 360 ° and four axial stroke movements.

A return line 60 and 62, respectively, is branched off from the outlet channel 40 and the inlet channel 36 and communicates with the rear displacement 9 via openings 64 and 66. In order to control the opening and closing of openings 64 and 66, an arrangement of valve flange 48b, sealing washer 50b, valve slots 52b, 54b and springs 56b corresponding to the working side is provided on the back, which in principle is the same as the corresponding arrangement on the working side works.

Because of this arrangement, a part of the exhaust gas flowing through the exhaust duct 40 (for example a third to a quarter of the amount of exhaust gas) is emitted during the exhaust stroke. sucked through the return line 60 into the rear displacement 9. In the subsequent work cycle suction, the exhaust gas located in the displacement 9 is moved via the return line 62 into the inlet line 36, and this amount of exhaust gas flows together with fresh fuel gas through the inlet opening 38 into the working displacement 8.

This results in a preheating of the fuel gas and thus a rapid warming up of the engine to its operating temperature, which results in optimal ignition and combustion and a corresponding reduction in pollutant emissions.

The proportion of the gas branched off to the return side can be dimensioned by appropriately dimensioning the return lines 60, 62. It goes without saying that the metering can also be carried out by a correspondingly controlled valve device (not shown). The latter possibility has the advantage that the return of the exhaust gas to operating states with a heat deficit such as the cold start can be limited.

In order to avoid that too large a negative pressure occurs in the rear displacement 9 during the compression stroke, a recess (not shown) can be provided in the piston 10, which increases the volume of the rear displacement 9. In addition or instead of this, it is also possible to allow air to flow in from the inlet channel 36 or directly from the atmosphere by means of a corresponding valve control.

It goes without saying that the drive shafts of further cylinders can be coupled to the drive shafts 16a, 16b - either directly or via gears.

3, 3a and 4, coolant channels 68 for cooling the cylinder are indicated. Further details of the internal combustion engine that are not necessary for understanding the invention, such as e.g. the lubricant supply has been omitted for the sake of simplicity.

However, it should be noted that longitudinal lubricant bores in the screws 26 provide precise lubrication of the positive guide 20, i.e. the balls 24 and the groove 22 and the piston 10 can take place.

Claims (12)

1. A four-stroke internal combustion engine of the piston type including at least one cylinder for slidingly and sealingly receiving a cylindrical piston, a work space being provided on one workside between an end wall of the cylinder and the adjacent end wall of the piston, an inlet opening communicating with an inlet passage for feeding combustion gas into the work space, an outlet opening communicating with an outlet passage for discharging exhaust gas from the work space, and valve means for opening and closing said inlet and outlet openings in conformity with the work strokes, the piston (10) being mounted in the cylinder (2) for axial and rotary movements and a serpentine guide means (20) being provided between the piston (10) and the cylinder (2) for causing the piston (10) to perform four axial work strokes when rotating about 360°, and a shaft stub (14a) coaxial to the piston (10) being provided for outputting the rotary movement of the piston (10), characterized in that the cylinder (2) and the piston (10), at their peripheral walls in the area of their adjacent end faces, each comprise one combustion chamber portion (32, 34) which combine to form a combustion chamber (30) at the time when the combustion gas is being ignited such that the combustion gas expanding in the combustion chamber (30) exerts a torque upon the piston (10).
2. A four stroke internal combustion engine according to claim 1, characterized in that said guide means (20) comprises a serpentine groove (22) of semicircular cross-section in the peripheral wall of the piston (10) and a pair of diametrically opposite balls (24) mounted in the peripheral wall (4) of the cylinder (2) and engaging into the groove (22) of the piston (10).
3. A four stroke internal combustion engine according to claim 1 or claim 2, characterized in that the two combustion chamber portions (32, 34) each are of substantially triangular shape in a plane perpendicular to the axis of the cylinder so as to form a rectangular combustion chamber (30) having a drive surface (34') in the piston (10) transverse to the circumferential direction and a reaction surface (32') in the cylinder (2) substantially parallel thereto.
4. A four stroke internal combustion engine according to any of the preceding claims, characterized in that said shaft stub (14a) is mounted in a drive shaft (16a) so as to be axially movable and to be prevented from rotary movements for compensating for the axial movements of the piston (10) and for outputting the rotary movements of the piston (10), which drive shaft is mounted in the cylinder (2) so as to be rotatable and to be prevented from performing axial movements.
5. A four stroke internal combustion engine according to claim 4, characterized in that the shaft stub (14a) and the drive shaft (16a) are of angular, preferably hexagonal or octogonal cross-section.
6. A four stroke internal combustion engine according to claim 4 or claim 5, characterized in that each side of the piston (10) includes a shaft stub (14a, 14b) and a drive shaft (16a, 16b).
7. A four stroke internal combustion engine according to any of the preceding claims, characterized in that the valve means comprises a valve flange (48a) including a valve slot (54a) extending through the valve flange which is mounted in the end wall (6a) of the cylinder (2) so as to be rotatable along with the piston (10) such that the valve flange (48a) together with the valve slot (54a) is arranged to open and close the inlet and outlet openings (38, 42) in timed relationship to the work strokes.
8. A four stroke internal combustion engine according to claims 4 and 7, characterized in that, for sealing purposes, to prevent leakage losses, a sealing disk (50a) having a valve slot (52a) extending therethrough is mounted in a recess of the valve flange (48a) so as to be axially movable and is arranged to be urged against the adjacent end wall (6a) of the cylinder (2) by springs (54a) supported against the valve flange (48a), an axial projection which extends about the valve slot (54a) of the valve flange (48a) being slidingly received in the valve slot (52a) of the sealing disk (50a).
9. A four stroke internal combustion engine according to any of the preceding claims, characterized in that a rear work space (9) is provided between the piston (10) and the cylinder (2) on its rearside remote from the work side.
10. A four stroke internal combustion engine according to claim 9, characterized in that the rear work space (9) communicates with the inlet passage (36) and the outlet passage (40) by respective return conduits (60, 62) such that a portion of the exhaust gas from the outlet passage (40) is refed into the rear work space (9) and from there, along with fresh combustion gas, via the inlet passage (36) into the work space (8) on the work side.
11. A four stroke internal combustion engine according to any of the preceding claims in connection with claim 4, characterized in that the drive shaft (16a) is coupled to the piston of a further cylinder.
12. A four stroke combustion engine according to any of the preceding claims, characterized in that it is of the Otto-type and that an ignition means (36) is disposed in the combustion chamber portion (32) of the cylinder (2).

Images