OPPOSED PISTONS

Field of the invention

The invention concerns the design of an unconventional solution for combustion and compression ignition (CI) engines, through a simplification in their kinetic joints to increase their total efficiency.

Prior art

Today's combustion engines apply the conversion of a piston's reciprocating linear motion into a rotation with the help of a crankshaft mechanism.

Expansion pressure produces force at the piston face, which is linearly reduced when the piston moves from the top dead centre (TDC) towards the bottom dead centre (BDC). The same, but reversely oriented passive force impacts on the cylinder head.

The crankshaft mechanism distributes the expansion pressure on the piston so inexpediently that its maximum values at the TDC and after TDC create either no torque or only a minor one. This power only creates increased pressures in the connecting rod's bearings and the crankshaft.

Similarly at the bottom dead centre BDC and before BDC, the torque becomes geometrically reduced, approaching zero. The expansion power in this area is small, and therefore torque decreases are not so distinct as at the top dead centre and after TDC.

In this connection, the most beneficial proportional combinations have been implemented, and there has been no development past the current symbiotic bond of piston, connecting rod and crank, and there are no indications of significant improvement on this. The output of rotary engines depends directly on torque and revolutions. This fact has led engineers of combustion engines to increase the engine's revolutions significantly in recent years; this is enabled by both the present level of engineering, materials and technology knowledge and progress concerning fuels and lubricants. However, its effect results in shortening the period for rational fuel utilisation.

The decisive indicator for judging combustion engines is fuel consumption per generated power unit, along with keeping to set emission limits, which will only tend to decline.

Nowadays the overall technical level of combustion engines is so sophisticated that further research and development is only expected to bring partial achievements that will asymptotically approach the exhaustion of all possibilities. The combustion engine's efficiency growth will thus come to a halt at the level dictated by technological possibilities.

In contrast to the submitted invention, the solution according to document SK 285842 B6 applies a different means of torque transfer (using a crankshaft), while also using self-acting valves.

Similarly, the solutions according to DE 19857734 A1 , DE 2746203 A, and SK 3731 U use a well-known crankshaft for torque transfer.

The FR 2732722 A1 solution involves pistons that are not opposed, which results in energy loss due to passive pressures. This solution also uses two cylinder heads with the consequence of a huge loss of energy. Side pressures at the cylinder walls occur during operation. The use of valves is assumed.

The document according to FR 2906332 A1 describes a solution using a link with better torque transfer instead of a crankshaft. Yet this is a rather complicated solution, expensive and prone to malfunction. Furthermore, passive pressures on the cylinder head play a negative role, bringing about huge energy losses. Again, the use of valves is anticipated.

In the CZ 1999-3707 A solution, the engine uses a different torque transfer, similar to the crankshaft mechanism, yet with a huge torque loss.

Torque transfer under SK 4492 U applies another approach (sliding element).

Most of the solutions hitherto are based on the use of a crankshaft. Still, the applicant deems such solutions to be less efficient with respect to torque transfer compared to the submitted solution. Moreover, known combustion engines mostly anticipate the use of valves, where lower efficiency when scavenging the cylinder is a disadvantage. Another drawback with the majority of existing solutions is the occurrence of passive pressures impacting the cylinder head causing energy loss.

Therefore, the inventor's task was to design a solution efficient in terms of torque transfer and simple in its construction.

Summary of the invention

The designed valve-free four-stroke combustion engine with axially opposed pistons applies a periodical workflow like a conventional engine. Intake, compression, expansion and exhaust are performed during two revolutions of the crankshaft.

A pair of opposing cylinders and pistons located in the engine block hole forms one common combustion chamber - a so-called working unit.

There can be several working units in the block, their axes running in parallel with the shaft axis. Working units are organised around the shaft in a circle. The odd number thereof (1 , 3, 5) guarantees that we avoid an indifferent point in the process of transforming a linear motion into a circular motion.

The pistons' linear motion transforms to circular with the help of two inclined plates moving together with the shaft. Working hemispheres slide along their inner surfaces and reversible hemispheres slide along their outer surfaces.

Hemispheres are placed in the ball joints of connecting rods and their instant centres of rotation are on the plate's corresponding surfaces. The inclined plates, placed "against each other", begin to rotate, impacted by expansion forces driven from both pistons via connecting rods and their working hemispheres, using the principle of motion over a tilted plane. When the pistons and connecting rods move in reverse, the accumulated energy of the flywheel makes the reversible hemispheres slide along the inclined plates' outer surfaces. The intake and exhaust processes are facilitated by the cylinders themselves. As cylinders rise from their cases a ring-shape vent is opened in a corresponding time interval on the side of either intake or exhaust. These vents are connected to the intake or exhaust pipe.

Cylinders rise either mechanically or electromagnetically. The so-called overlap may be resolved by suitable "timing" of the cam disc functional surface. The cam disc rotates by means of a planet gear mechanism connected to the shaft in the ratio 1 :2 and by means of an operating lever the cylinder is pushed up, which opens up the relevant vent. Cylinders are being pushed back into their cases by a spring.

The unconventional engine design of the presented invention has several advantages:

- the designed engine is simpler overall, and compared to a conventional engine it lacks cylinder heads, crankshaft and camshaft, including valves and their distribution mechanisms

- it enables the use of expansion force at its peak

- linear distribution of torque throughout the expansion force's impact

- elimination of passive pressures in the combustion chamber

- compression rate is not determined by valve trajectory

- dynamic effects produced by moving parts are lower in total. The movement of heavier cylinders is 2-to 3-times lesser than the stroke of valves in classic engines. This minimises the acceleration and thus the dynamic force in their movement

- it is possible to set revolutions more rationally with respect to the time necessary for fuel utilisation

These advantages translate positively into the total efficiency value of the said engine.

The design solution applies some elements which have yet not been verified in practice.

These are:

- opening the intake and exhaust channels by means of the actual cylinders' stroke and of their sealing, particularly in the exhaust area. - keeping the cylinders in casings by means of pressure springs. Theoretically, the axial force caused simply by the friction of a piston and its rings against the cylinder wall will act against the spring.

Brief description of the drawings

Fig. 1 Schematic sectional view of two working units of the engine, with intake terminating in one unit and expansion occurring in the other unit simultaneously Fig. 2 Longitudinal sectional view of the engine's working unit

Fig. 3 Sectional view A - A runs radially through the engine's centre. From the functional aspect, the sectional plane divides it into two identical imaginary halves.

Fig. 4 Sectional view B - B runs through the collecting ring-shape vent leading into the exhaust pipe

Fig. 5 Sectional view C - C runs through the planet gear of cam disc 11 and operating lever 12

Fig. 6 Sectional view D - D runs through inclined plate 2, connecting rod with cog 3 and its prismatic joint 9

Detailed description of the preferred embodiments

The engineering solution of the designed valve-free four-stroke combustion engine with axially opposed pistons (Fig. 1 ) has two identical parts, namely the front and rear parts, mutually connected by the engine block 6 and the shaft 1, which is placed in the engine block 6 on two axially-radial bearings and horizontally running through the entire engine.

The cylinders 5 are inserted into the engine block 6 from both sides; the cylinders are placed so as to allow a sliding motion and are sealed against the block with suitable sealing. These cylinders 5 rest in casings pressed onto both sides of the engine block 6. Each cylinder 5 is held in its casing by a spring 13 against the guiding disc 16, which makes it possible for the cylinder 5 to move horizontally.

Between the guiding disc 16 and the cylinder 5 is sealing that closes off the engine block 6 space. The space is filled in with coolant (ideally with the same type of oil as that used in the engine).

The shaft 1 runs freely through the middle of the guiding disc 16; the shaft has cogs that drive the cam disc H via satellites 10 at a revolution ratio of 1 :2.

The cam disc H moves the cylinder 5 by means of the operating lever 12 and opens the compression area at the desired interval.

Optimum distribution of expansion sequence in individual cylinders (to the extent of two revolutions) makes it possible to reach the cam disc H with several functional routes. This makes possible for the designer to choose a suitable side for intake or exhaustion.

Pistons 4 are fitted into cylinders from both sides and are joined to a connecting rod with cog 3 by means of a piston pin. From the inside, the connecting rod is equipped with a working hemisphere 7 and a reversible hemisphere 8 on the opposite side. Hemispheres 7 and 8 are placed in the rod's cog 3 in ball joints.

The saddle of reversible hemisphere 8 determines the free play between the inclined plate 2 and the two hemispheres 7 and 8, whose centres of tilting lie on the inner and outer surface of the plate 2. Thus the centres of both hemispheres 7 and 8 always lie in a straight line parallel to the axis of shift of the cylinder 5, the pistons 4 and the connecting rod 3, whose cog is placed in the prismatic joint 9 attached in the saddle of the guiding ring 14.

The rotating inclined plate 2 is levelled in the interior diameter of the guiding ring 14 whereby the movement of a connecting rod with cog 3 is limited and allows it to move only axially.

The engine space is closed by front disc 15 from the front part and from the back part by closing disc 17. List of reference numbers

1 shaft

2 inclined plate

3 connecting rod with cog

4 piston

5 cylinder

6 engine block

7 working hemisphere

8 reversible hemisphere

9 prismatic joint

10 planet gear

11 cam disc

12 operating lever

13 spring

14 guiding ring

15 head disc

16 guiding disc

17 closing disc