EP2425107A1

EP2425107A1 - Rotary piston internal combustion engine

Info

Publication number: EP2425107A1
Application number: EP10770017A
Authority: EP
Inventors: Kjell Salomonsson
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-04-27
Filing date: 2010-04-27
Publication date: 2012-03-07
Also published as: EP2425107A4; WO2010126425A1

Abstract

The invention concerns a rotary piston engine (1) that includes at least two straight circular cylinders (7), which are parallel with each other and connected to each other along a longitudinal cylinder jacket opening. In the cylinders (7) pistons (2, 3) are arranged rotably journaled in the cylinders (7). A sealing rod (6) is arranged in said cylinder jacket opening and is displaceable across the pistons (2, 3) in sealing contact with mantle surfaces of these. The pistons (2, 3) have central circular cylindrical parts, which have smaller diameters than the cylinders (7) and two opposite protruding wings each, that radially outward define exterior piston mantle surfaces, substantially having the same diameter as the cylinders (7), and are arranged to slide closely along jackets (8) of the cylinders (7). In the cylinder jackets (8) there are pairs of exhaust and intake openings (10-13), which are opened and closed by flap valves (9a-9d) and lead to different working chambers. In a certain rotational position of the pistons (2, 3) together with the sealing rod (6) and an opposite cylinder jacket part (8) they form a combustion chamber in said cylinder jacket opening.

Description

Rotary piston internal combustion engine

Technical Field

The present invention concerns a rotary piston engine according to the preamble of claim 1.

Prior Art

In the prior art different rotary piston engines are known. The preamble of claim 1 is based upon the engine according to US 3 324 839, that also has a sealing rod placed between two pistons. In the engine, by means of a crank arm suspension the pistons roll in the cylinders, and a sealing rod formed like an intermediate sealing roller is governed by a complicated linkage system. This is very complicated and moreover it means that no power can be gained directly from the pistons. In GB 1 377 802 a similar solution is described with an eccentric rotor between cylinders. These create a counter force at a working stroke and do not manage to lead all of the fuel mixture to a combustion chamber. Moreover, a back sweep is formed in the intake, which limits the amount of fuel mixture that reaches the compression chamber. Other previously known solutions are to be found in for example in

US 3 861 362, US 3 364 906 and FR 1 093421. They are all characterised by use of eccentric pistons.

Finally, within the area of rotary piston engines, the Wankel engine has to be mentioned. A problem with it has shown to be that its oscillating pistons create sealing problems against the cylinder walls and that the shape of its combustion chamber leads to unfavorable combustion because of an extended long gap with a large cooling surface. This leads to the combustion becoming incomplete and also leads to high fuel consumption and high exhaust emissions. Object of the invention

Against that background, the object of the invention is to improve a rotary piston engine according to the preamble such that the previous problems with this type of engine are removed.

Short Summary of the Invention

The object of the invention is achieved by means of a rotary piston engine according to claimi, wherein preferred embodiments of said rotary piston engine are objects of the sub claims 2-10.

Short Description of the Drawings

On the drawings two different embodiments of a rotary piston engine according to the invention are shown schematically, wherein:

Fig. 1 is a longitudinal sectional view of a first embodiment of the en- gine;

Fig. 2 is a cross sectional view of the engine in fig. 1 ;

Fig. 3-7 illustrates working cycles of the engine in figs. 1 and 2; and

Fig. 8 shows a second embodiment of the rotary piston engine according to the invention.

Description of Two Embodiments

The rotary piston engine according to the invention works with rotary pistons and has in addition to that a pump function. The engine is primarily intended to be used as a source of power in vehicles and mobile machines, but can also be used in stationary applications. The engines of today are both large and heavy, costly to produce with many movable parts and consume a superfluous amount of fuel, which for no use drains the natural resources.

The engine according to the invention is compact and light, simple to produce and symmetrically designed, has few movable parts, is fuel saving and can probably to a large extent be built of ceramic material. Moreover, the engine needs to be built only in a few different sizes, since one can choose output power by engaging or disengaging engines to or from an output shaft. Unlike conventional four-stroke engines, that transfer piston power by means of piston rods, the engine works very even, since no pistons have to be accelerated and decelerated and thus stopped at dead centers, which both lead to a loss of power and create major vibrations difficult to compensate for. Moreover, in four-stroke engines the space, in which the crankshaft works, that is the crankcase, cannot be used for power generation and hence constitutes a part that takes up space for no use and even creates a loss of power, since the moving pistons compress and thin the air in the crankcase. Further timing belts, camshafts, rocker arms and valve springs draw power, which deteriorates the efficiency of the four-stroke engine.

A further disadvantage is that a piston in a four-stroke engine generates power only each second revolution, which means that the piston is forced to move one and three quarter revolutions without generating any power at all. This is a big drawback, since it means increased friction, an un- suitably large engine and moreover masses, that counteract acceleration and deceleration.

The same problems occur with a two-stroke engine too, although the piston in that case only does an unnecessary three quarter revolution. On the other hand, it is difficult to optimally fill and drain the cylinder with and from fuel mixture at different speeds, and therefore one loses more than one gains regarding power yield and environmentally harmful combustion gas emissions.

The rotary piston engine according to the present invention comprises an engine block 1 with two almost circular cylinders. In the centers of the cy- linders, two pistons 2,3 with shafts 4 are joumaled in sides of the engine block. The pistons are circular, wherein approximately a fourth of their periphery is grooved on both sides, so that a sealing rod 6 permanently sealingly abuts the pistons. The pistons are interconnected by means of gear wheels 15,17 and an intermediate gearwheel 16 or a toothed belt arranged outside of the engine block one quarter of a turn displaced, so that said gear wheels rotate in the same direction and with the same speed. The sealing rod 6 (that comprises of a light and rigid material having a surface which is elastic and heat-resistant) is carried on the sides of the engine block in guide ways 18, so that it can move between the centre points of the pistons. The mounting of the sealing rod does not necessarily need to be limited to one plane only, but can follow a bent path or be connected to the crank by mechanical control. The important thing is that it at all times seals against the pistons. The length of the pistons should not exceed their diameter, and the groove and thus the caliper of the sealing rod should be adapted to an optimum relation. Furthermore, there are openings along the entire length of the engine block, two for each cylinder, which are in turn divided into four gaps 10-13, which are controlled by springing valves by means of piston move- ment. The valves 9a-9d with springs 20 rock about their shafts 19a-19d and have a double function, as they both open and close both gaps concurrently. The gaps 10-13 are in turn connected to funnel shaped nozzles to inlet and outlet ducts. It all contributes to a very efficient degree of filling and emptying, respectively, along the entire lengths of the cylinders. When the pistons are rotating they form different chambers A-H, wherein chambers G, C, that are formed in the middle of the engine, seal against the sealing rod. In certain chambers intake, compression, ignition, power generation and exhaust of fuel mixture are performed, while in the exterior chambers only intake and outlet of air occurs. The entire process is repeated twice per revolution on each side, thus four power strokes per revolution, what corresponds a conventional eight cylinder four-stroke engine.

In the drawings the rotary piston engine shown works with compression ignition (e.g. diesel fuel) and therefore without controlled heat (spark ignition). For another type of fuel (petrol, ethanol and others) the combustion chamber has to be larger and has to be supplemented with an ignition apparatus.

In the encircled part the drawings (in middle part to the left) one can follow the clockwise movement of the upper piston 2. In chamber B the valve 9a has opened, and by the vacuum that arises a certain amount of air is sucked in via the inlet duct 12 via a throttle valve. An injection nozzle 14, that is designed for spreading sideways, so that the fuel mist is distributed along the entire cylinder, mixes the inlet air to a matching fuel mixture, corresponding to the intake stroke. After yet another quarter revolution the valve 9a has closed and compression started, corresponding to the compression stroke. An eighth part of a revolution later the sealing rod 6 is pressed down by the cam of the piston and closes the combustion chamber C. At the same time the valve 9a is opened again, new air is sucked in and a new injection phase is started. Now the fuel is so compressed that it self-ignites, and the piston just manages to close the valve 9b, when the fuel expands into the chamber D. Observe that the combustion takes place in a narrow gap where the expansion becomes concentrated, with small cooling surfaces, using power optimally (compare to a common piston engine, where power is distributed along large cooling surfaces). Now the bottom one 3 of the pistons on the drawings has its top cam pressed down (clockwise) by the expanding fuel mixture and the power stroke is started with high torque. After yet another eighth part of a revolution the power stroke in chamber D has been completed, at the same time as the cycle is restarted in chamber C. The entire cycle is completed after having finished a half revolution. An eighth part of a revolution later the valve 9b opens the exhaust duct 13 and starts an exhaust stroke on the left side of the bottom piston 3 at the same time as the compression stroke is started in chamber C of the top piston as already described. After another eighth part of a revolution the exhaust stroke in chamber

D is concluded and the piston has closed chamber C, in which compression is taking place. The same development occurs with a quarter revolution displacement in the right chambers F, G and H, where the valves 9c and 9d open and close the intake duct 12 and the exhaust duct 13. The top chamber A and the bottom chamber E suck ambient air through the intake ducts 11 and blow air through the exhaust ducts 10 twice per revolution each. The air cools the engine, when necessary via tubes between the ducts and via T- tubes with thermostatic valves, which control the amount of ambient air and exhaust air or returned preheated air (when cold starting) in order to quickly reach a sufficiently high working temperature, which is important because cooling surfaces lead to incomplete combustion. The heated up exhaust air can be used in a heater for the passenger compartment of a vehicle and/or as additional charge air via a charge air cooler to the intake ducts. The spring biased valves 9a-9d only lead to frictional losses, and when the valves open they assist in depressing the piston cams and, in this way, they regain the spring force, which is different to conventional valves, where the spring force is entirely wasted. Apart from the sealing rod 6 there are sealing and lubrication rings on each side of the pistons in the cylinder block 7 (alternatively on sides of the pistons) as well as sealing and lubrication bars in the periphery of the cylinder block 8. The lubricant is suitably distributed from an oil cooler tank, which is pressurised through a shunt from the pumps of the cylinder (possibly the oil is used also to cool the pistons internally via ducts around the piston shafts). Power can be taken off at both ends of the piston shafts 4, thus at four places, which simplifies and minimizes power transmission losses, e.g. for the cranking motor, the generator, the power steering and the air conditioning compressor. The engine is also equipped with a continuous engageable and disengageable drive shaft 5 in one of the piston shafts, which makes it possible to consecutively engage onto and start several engines to one shaft and thus to deliver power as required. Engagement and disengagement suitably is performed by means of electrical mesh clutches or sliding clutches 21 , which are controlled by a computer box through sensors sensing speed versus throttle level.

Suitably the engine units are divided into a master engine, on which the necessary auxiliary units, such as the crank motor, the generator, the power steering, etc., are arranged, and other engine units, which are engaged and started gradually. For example at standing still only the master engine is working, at starting the slip clutch is activated and the driving shaft is rotated and the second engine is engaged and started. At increased acceleration the third engine is engaged and started, at additional acceleration and speed the fourth engine is engaged and started, etc. The engagement and disengagement of the engines does not necessarily have to be governed by means of a computer unit, but can also be dealt with manually from the driver's seat. It is obvious that this arrangement saves fuel and is environmentally, and at the same time the risk for engine halt is reduced as there are several engines to use. The exchange and repairing costs are lowered too, because a small engine is less pricy.

The engine may also be built with a plurality of pistons, an additional piston (c.f. fig. 8, three pistons) and produce twice the power (eight strokes per revolution). As the engine works continuously, without dead points (four strokes per revolution), it can run on very low speed from approximately 200 rpm, and at very high speed, too, in excess of 12 000 rpm. On the high end speed is likely restricted by the valve springs 20 running in trouble to manage in time. In all and along with the engagement possibility it means that a tradi- tional clutch pedal is not needed and that a gearbox possibly can be excluded.

It is well-known that a fuel mixture expands at combustion and that this fact is used in order to produce power. The fact has given rise to a multitude of different types of engines aiming at optimally taking care of the expansion force. So far piston and crank have been the most successful concept in order to drive vehicles and machines. The problem with today's engines is however that the efficiency is rather poor (maximum 50%). The remaining energy is dissipated as non-used heat energy. To a large extent this is due to the combustion not being optimal and due to the amount of movable parts leading to frictional losses, that produce heat instead of useful energy. This gives rise to unnecessary environmentally hazardous exhaust gases, such as carbon dioxide, different nitrogen compounds and hydrocarbon emissions. Due to its working cycle, the traditional structure becomes large and heavy too, because there has to be room for e.g. non working pistons, a flywheel, a possible gearbox, a crankcase, a water jacket, cam gears, a camshaft with rocker arms and valves, a water pump, an oil pump, drive pulleys with belts for sub units and a couple of other space requiring functions. It is obvious that a more compact and more effective engine would be capable of reducing waste of natural resources and spare our vulnerable environment too, where the envi- ronment objectives otherwise become difficult to achieve.

Claims

1. Rotary piston engine (1) including at least two straight circular cylinders (7), which are parallel with each other and connected to each other along a longi- tudinal cylinder jacket opening, that stretches along the entire length of the cylinders (7), wherein pistons (2, 3) are arranged in the cylinders (7) rotably joumaled in opposite ends of the cylinders (7), and wherein a sealing rod (6) is arranged in said cylinder jacket opening, the sealing rod (6) being parallel with the cylinders (7) and displaceable across these in sealing contact with mantle surfaces of the pistons (2, 3), c h a r a c t e r i s e d in that the pistons (2, 3) have central circular cylindrical parts, that stretch along the entire length of the pistons (2, 3) and have a smaller diameter than the cylinders (7), as well as two opposite wings each, protruding from said circular cylindrical parts and also stretching along the entire length of the cylinders (7) and ra- dially outward defining exterior piston mantle surfaces, which substantially have the same diameter as the cylinders (7) and are arranged at rotation to slide closely along jackets (8) of the cylinders (7), wherein the pistons (2, 3) by mechanical engagement are arranged to rotate in same direction of rotation but a quarter revolution offset in relation to each other, so that in a certain rotational position said sealing rod (6) concurrently is in sealing contact against a protruding wing on one of the pistons (2, 3) and an indented mantle part of the other piston (2, 3), wherein the sealing rod (6) by means of the protruding wing is pushed through said cylinder jacket opening into the cylinder (7), whose piston (2, 3) in said rotational position has its indented mantle part facing said cylinder jacket opening, wherein in the cylinder jackets (8) pairs of exhaust and intake openings (10-13) are arranged, which starting from said cylinder jacket opening comprise of first an exhaust opening (13) and then an intake opening (11) within the first third of one piston revolution, after that an exhaust opening (10) and then an intake opening (12) within the last third of one piston revolution, wherein flap valves (9a~9d), that stretch along the entire length of the cylinders (7), are arranged in the middle of each pair of exhaust and intake openings (10-13) in order to concurrently open and close respective pairs of openings (10-13), wherein the flap valves (9a-9d) in an open stage by contact with mantle surfaces of the pistons (2, 3) keep the exhaust and intake openings (10-13) separated and thus in the cylinders (7) define exhaust and intake chambers, wherein the pistons (7) when the flap valves (9a-9d) are closed during the last part of a piston revolution before the displa- ceable sealing rod (6) form a compression chamber in one of the cylinders (7) and during the first part of a piston revolution after the displaceable the bar (6) form an expansion chamber in the other one of the cylinders (7) and in a transitional phase in between together with the sealing rod (6) and a meeting cylinder jacket part (8) in said cylinder jacket opening form a combustion cham- ber.

2. Rotary piston engine (1) according to the previous claim, wherein said sealing rod (6) is displaceable across the cylinders (7) along guides (18), that stretch along a radius between axes of rotation of said pistons (2, 3).

3. Rotary piston engine (1) according to claim 1 or 2, wherein the intake openings (11), that are located within the first third of a piston revolution, and the exhaust openings (10), that are located within the last third of a piston revolution, are arranged to suck in and to pump out cooling air.

4. Rotary piston engine (1) according to claim 3, wherein pumped out cooling air is used for pressurizing of charge air to the engine (1).

5. Rotary piston engine (1) according to claim 3, wherein pumped out cooling air is used for pressurizing of oil for the engine (1).

6. Rotary piston engine (1) according to claim 3, wherein pumped out cooling air is used for heating of an heater.

7. Rotary piston engine (1) according to one of the previous claims, wherein shaft necks (4a~4d), that is linked to the pistons (2, 3), protrude at ends of the cylinders (7).

8. Rotary piston engine (1) according to claim 7, wherein at least some of said shaft necks (4b, 4d) are linked to gears (15, 17), which mechanically interconnect the pistons (2, 3).

9. Rotary piston engine (1) according to one of claims 1-8, wherein the valves (9a-9d) of the engine (1) are biased towards open state by means of springs, and wherein their opening and closing is controlled by the contours of the pistons (2, 3).

10. Rotary piston engine (1) according to one of claims 1-8, wherein the valves (9a-9d) of the engine (1) in two cylinders (7) located next to each other for a coordinated opening and closing action are diagonally interconnected by means of a linkage system.