The present invention relates to a rotary-piston internal-combustion engine.
An internal-combustion engine is known that consists of a rotating block of a rotational shape, with radially situated cylinders with pistons. Outside the rotating cylinder block there is a stationary case with intake and exhaust ports and so the rotational cylinder block together with the stationary case work like a rotary valve. Pistons are connected with a crankshaft by means of connecting rods. The crankshaft rotates at different revolutions than the rotating cylinder block and they are coupled by means of gearing.
There are known designs of two, three and multi cylinder arrangements of engines with rotating block of the rotational shape with radially situated cylinders with pistons. Outside this rotating cylinder block there is a stationary case with intake and exhaust ports. The rotating cylinder block serves as a rotary valve at the same time. Pistons are connected with the engine crankshaft by means of any of known mechanisms for converting straight movement of a piston to the rotating one of a crankshaft. The engine crankshaft is coupled with the rotating cylinder block by means of gearing. None of those designs has achieved wider enlargement and utilization despite the undoubted potential.
There are many reasons why these engines were not successful. These engines were designed with usual bore/stroke ratio and the engine dimensions were then too large. Rotation of a big block is then problematic in terms of high inertia forces, deformation of the big outer stationary case, cylinder cooling etc. Another negative feature of these designs was the seal between the rotating block and the stationary case. The cylinder space was mostly sealed to the stationary case by a seal, which was placed in the rotating cylinder block. This seal was then exposed to centrifugal forces that are caused by rotation of the cylinder block. That seal was consequently more loaded, there were high friction losses and lubrication problems. Such designs are described e.g. in patents DE2732779, DE2153946A1 or FR2767156A1.
The above-mentioned deficiencies are removed to a large extent in a rotary-piston internal-combustion engine with a rotating block with three radially situated cylinders with pistons and an outside placed stationary case with two intake and two exhaust ports, while three connecting rods are connected to an one-pin crankshaft and between the crankshaft and rotating block there is gearing with a gear ratio Ncrankshaft/Nblock=−3, and in the stationary case there are at least two spark plugs and/or two injection nozzles placed on the opposite sides. The essence is that the bore/stroke ratio is 2 to 3.5 and all sealing parts that seal cylinder space to the outer stationary case, i.e. side and transverse sealing parts, are placed in grooves in the outer stationary engine case and sit down on the outer surface of the rotating block.
All three connecting rods have a forked big-end eye, while two connecting rods are asymmetrical, identical and they fit into each other and the third connecting rod is wider, symmetrical and all of them are placed on one sleeve, which is revolvably placed on a single crank pin.
The rotary-piston internal-combustion engine has advantageously pistons with holes in the piston walls for conducting the oil away and the rotating cylinder block has cavities for cooling oil.
The engine can consist of multiples of three-cylinder engine units, while it can be advantageously provided with one shared gearing between the rotating block and engine crankshaft, which has the same number of crank pins as the number of multiples of three-cylinder engine units.
The rotary-piston internal-combustion engine enables the 4-stroke cycle work without using lifting valves. Cross-sectional areas of exhaust and intake ports are large, they open and close relatively quickly and they enable to maximally fill the cylinder, maximally utilize the expansion and minimize flow losses in ports, even at high engine speeds. The compression ratio can be adjusted arbitrarily. There are no obstructing lifting valves with high temperature in the combustion chamber. That improves the resistance to knocking. It is possible to place more spark plugs in the combustion chamber and so ensure optimal combustion even with high cylinder bore diameter and at high engine speeds. The combustion chamber can be made in any shape by shaping the piston crown. Any anti-detonation slots can be also created. It is also possible and advantageous to create any shape of the piston and port with respect to combustion chamber scavenging at the end of exhaust and beginning of intake. The engine can be well balanced. It is a rotating star three cylinder engine, indeed.
Smaller outer diameter of the rotating block is achieved thanks to high bore/stroke ratio and minimal length of connecting rods. That leads to small outer dimensions of the engine, better utilization of inner space and small weight. Small dimensions of the rotating block and relatively low speed of the rotating block with respect to the crankshaft allow to reach relatively small sliding velocities at the seal on the perimeter of the rotating block.
Thanks to placing the sealing parts of the rotating block in the stationary case, there are neither centrifugal nor any other inertia forces acting on them. That decreases lubrication demands as well as mechanical losses by friction of those parts and improve their durability and reliability.
That is a significant advantage of the rotary-piston internal-combustion engine over the Wankel rotary engine. Compared to the Wankel engine it also have a better seal thanks to multiple sealing parts of the rotary block and planar contact of sealing parts, a better shape of the combustion chamber, higher attainable compression, easier manufacturing and repair.
It is possible to reach very high engine speed with this rotary piston engine due to minimization of dimensions of the rotary block, decrease of friction velocities at its perimeter and due to the fact that the sealing parts of the rotating block are not loaded by inertia forces. The engine therefore achieves higher specific performance and weight parameters due to the higher achievable engine speeds.
The rotary-piston internal-combustion engine uses a standard crankshaft mechanism with pistons and piston rings, which is perfect in terms of design and technology.
When using the rotary engine as an aircraft engine there is an advantage in small gyroscopic moment of this engine, because the rotating cylinder block revolves in the opposite direction than the engine crankshaft. It is advantageous to use the rotating cylinder block to drive the propeller, because the rotating cylinder block rotates at three times smaller speed than the engine crankshaft.
This piston rotary engine will enable realization of a simple, production-cheap four-stroke combustion engine of small dimensions, with small number of moving parts, with balanced and silent working and high specific performance.
The rotary-piston internal-combustion engine according to the invention will be clarified on a model engine by means of enclosed drawings. Therein:
The model rotary-piston internal-combustion engine according to the
The embodiment of the rotary-piston internal-combustion engine according to the
The function of the rotary piston combustion engine is following. While turning the crankshaft, the engine works in a standard 4-stroke cycle. The piston 5 draws fresh charge into the cylinder 16 from the intake port 6, then there is compression, ignition by a spark plug 15, expansion and consequent exhaust into the exhaust port 7. The whole cycle is done during 0.5 revolution of the rotating block 2. In the meantime the crankshaft 3 does 1.5 revolutions in the opposite direction and the relative motion between the crankshaft 3 and the rotating block 2 then accounts for two whole revolutions, which are necessary for a 4-stroke cycle. The working of the engine is schematically shown in the
The rotary-piston internal-combustion engine according to the invention can be used for e.g. driving small aircrafts, motorcycles, racing cars and in other applications, where high performance and small weight and dimensions of an engine are of primary interest. Thanks to its simplicity and small dimensions it can be also used for driving standby generators etc. Provided that the lubricating oil consumption is significantly limited it is possible to consider application in conventional vehicles or hybrid vehicles. The engine is basically suitable for running on hydrogen or other alternative gaseous fuels.
Number | Date | Country | Kind |
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PV 2012-820 | Nov 2012 | CZ | national |