WO2017168128A1

WO2017168128A1 - Rotary internal combustion engine

Info

Publication number: WO2017168128A1
Application number: PCT/GB2017/050828
Authority: WO
Inventors: Owen Geoffrey JORDAN
Original assignee: Jordan Owen Geoffrey
Priority date: 2016-03-28
Filing date: 2017-03-23
Publication date: 2017-10-05
Also published as: GB201605159D0; GB2564056A

Abstract

A rotary internal combustion engine comprising an annular stator (10) which defines a circular-section chamber (11) in which a rotor (12) is rotatably mounted for rotation about the axis of the chamber (11). The rotor comprises radially-extending cylinders (15A, 15B, 15C) having outer ends in sealing but sliding contact with the inner surface of the annular side wall of the chamber (11). Pistons (16A,16B,16C) are displaceably mounted for axial movement in respective cylinders (15A, 15B, 15C) and are connected to a reaction point (18) disposed eccentrically of the rotor (12). The stator (10) has an ignition source (22), a fuel inlet port (21), an air inlet port (20) and an exhaust port (23) extend through the stator (10) into the chamber at respective circumferential positions for registering with the outer end of the cylinders (15A, 15B, 15C) at respective rotational positions thereof.

Description

Rotary Internal Combustion Engine

This invention relates to a rotary internal combustion engine.

The current market for internal combustion engines is split between spark ignition and compression ignition types, with two stroke and four stroke cycle versions of each. Most internal combustion engines comprise cylinders arranged in line or in a vee configuration. Such engines depend upon cast metal cylinder blocks and cylinder heads bolted together, with heavy crankshafts, camshafts and a variety of drive gear to operate the ancillary engine functions. Many include balance shafts to dampen the reciprocating forces. Because the engines depend upon reciprocating motion of the pistons in the cylinders, and contain significant gas pressures, the units are heavy and are of modest power to weight ratios.

Rotary internal combustion engines having radial cylinders are well known. One such engine is the Gnome engine of the type disclosed in US852033, which was widely used in World War 1 to power aircraft and comprises a rotor having a plurality of radial cylinders. Each cylinder comprises a piston connected via a connecting rod to a locus inside the centre of the engine. In use, the pistons are successively forced radially inwards by the pressure of the ignited fuel and air mixture, causing the rotor to turn as the locus moves and displaces the other cylinders.

Fuel and ignition where provided at the radially outer ends of each cylinder and, since each cylinder rotates as part of the rotor, such engines had notoriously complicated fuel supply and ignition systems. I have now devised an improved rotary internal combustion engine.

In accordance with the present invention, there is provided a rotary internal combustion engine comprising a stator having a stator body which defines a circular- section chamber in which a rotor is rotatably mounted for rotation about the axis of the chamber, the rotor comprising a radially-extending cylinder having an outer end in sealing but sliding contact with the inner surface of the annular side wall of the chamber, a piston displaceably mounted in the cylinder for movement axially of the cylinder and connected to a reaction point disposed eccentrically of the rotor, the stator having an ignition source, a fuel inlet port, an air inlet port and an exhaust port extending through the stator body into the chamber at respective circumferential positions for registering with the outer end of the cylinder at respective rotational positions thereof.

The present invention is a development of the Gnome rotary engine, where the rotor and the piston rotate about separate axes, but with the addition of a stator chamber having an annular wall against which the end of the cylinder seals and through which the ignition source, a fuel inlet port, an air inlet port and an exhaust port extend. The engine is inherently balanced, and if there are two or more cylinders, the power, exhaust and charge air cycles alternate between cylinders as the engine turns, giving a very smooth, almost vibration free, performance. The rotating mass of the rotor acts as an effective flywheel and the problems of fuel feed and ignition are addressed in this invention by substituting the multiple cylinder heads of Gnome engines, with a stator inside which the or each cylinder rotates. If there is more than one cylinder, the cylinders will be equally spaced around the circumference of the rotor.

The stator acts as a cylinder head to the or each cylinder that rotates within it, enabling a single service item, such as a fuel injector, to serve all cylinders in turn. One of each of the cylinder service components inlet, exhaust, fuel injector, spark plug (SI unit), glow plug (CI unit) is required for a complete engine, and the number of major moving parts is, in a three cylinder engine, seven i.e. three pistons, three connecting rods, and the rotor. There are only two major bearings, one being on an output shaft and the other on the reaction point of the piston. There are no ancillary drives or components such as a camshafts, valves, crankshaft, belts or pulleys, or balancing devices and thus the engine of the present invention is simple and inexpensive in construction.

The reaction forces of combustion are taken by the stator, which replaces previous heavy cylinder head castings, and the piston heads, the structural continuity being completed by the piston axle fixings in the stator. The cylinders are under no load apart from the compressed gas on the walls, and the torque component of the power output, taken via a reaction plane (a segment of a cylinder) between the cylinder wall and the side of the piston. The need for the cylinders to take loads from the cylinder head and crankshaft, via bearings and bolts, is obviated. The cylinders rotate under the influence of the reaction between the piston face and the annular side wall of the chamber, producing a resultant tangential torque on the cylinder walls of the rotor, which is transmitted to an output shaft fixed to the rotor. Plain bearings at the base of the piston connecting rods take the piston reaction forces as the radial component of the force generated in the combustion chamber. Preferably the air inlet and/or exhaust ports are elongate and extend circumferentially of the annular side wall of the chamber.

The air inlet and exhaust ports may partially co-extend over an angular region, so that the or each cylinder is exposed to both the air inlet and exhaust ports, so that pressurised air at the air inlet can assist to scavenge exhaust gas at the end of the exhaust period of rotation. Other gas/air mass handling systems may also be adopted with advantage, such as piston ports for scavenge.

With a single air inlet port, pressure changes (that can produce the classic diesel 'knock') are minimised as the one port serves the or each cylinder, enabling a strong, continuous, unidirectional flow in the incoming air to be established and maintained. The air inlet port is preferably equal in cross-sectional area to the bore of the cylinder and has a width which preferably at least as wide as the diameter of the cylinder(s): This allows air to be drawn into the cylinder(s) in a manner which is unrestricted by valves, valve stems, bifurcated ports or intermittent gas flows. The design of the fuel inlet port, air inlet port and exhaust port is not restricted by the presence of any other engine components, such as injectors, spark plugs, glow plugs or exhaust components. Closing of the inlet port is effected by the rotation of the cylinder against the annular side wall of the chamber. The end of the inlet port can be tapered or otherwise shaped to maximise the desired engine characteristics i.e. power, economy etc. Opening and closing of the exhaust port is equally effected and unencumbered by any of the normal issues encountered in conventional engines. Similarly, the scavenge cycle design is also free of the normal restrictions.

Means may be provided for applying lubrication between the inner surface of the chamber and the outer end of the or each cylinder. The rotor may comprise a rotor body having a circular outer surface which has a diameter slightly less than the internal diameter of the chamber, such that the rotor can turn freely inside the chamber, the or each cylinder forming part of the rotor body.

The tubular side wall of the stator may comprise an annular ring, for example formed of a high tensile steel, which is light in weight.

A rotary internal combustion engine in accordance with the present invention has the following advantages: a. It requires no poppet-type or other type of valves; b. It requires no camshaft or crankshaft, and no drive belts, chains or pulleys between the two. c. Just like a single cylinder engine, it solely requires a single spark/glow plug, a single air inlet duct and a single exhaust duct. These devices serve two, three, or more cylinders.

It requires no complex manifolds to split and join gas flows into or out of the engine. Air intake and exhaust gas flows will approximate to pulsed unidirectional steady state flows in all conditions, with no gas flows meeting or separating in the respective pipework.

Aspiration of the engine, formerly a problem with two stroke designs, is addressed by a substantial increase in the sectional area of the air inlet port compared with conventional engines. f. The rotation of rotor provides the stabilising inertia to prevent stall, and removes the requirement for a flywheel. The rotational masses of rotor may equate in total to approximately the mass of a conventional engine flywheel, though distribution of that mass will result in significantly greater inertia, and anti-stall capacity. The rotation of the rotor can also be used to provide sufficient air mass flow using a fan rotating with the rotor at engine speed to provide cooling. Water cooling may thus not be required.

The cooling air can be routed to the air inlet port, possibly with conventional after-cooling and turbocharging.

The scavenge cycle can also be designed to act as an EGR (exhaust gas recycling) process, eliminating the need for a separate EGR valve. j. The elimination of reciprocating parts, and the valves and their drive trains, will reduce energy losses. Any internal inertial losses will be limited to the oscillation of the pistons about their small end bearings; the connecting rods themselves and small end bearings in the pistons remaining in simple rotary motion with minimal axial oscillation. k. The mass of the connecting rods, pistons and their bearings add to the inertia of the engine to assist in stall prevention. I. The fact that the pistons and connecting rods, and their respective bearings, rotate, rather than reciprocate, will result in the use of less costly alloys; savings in mass in these components are no longer of any value in inertial or energy savings. m. Since there is no possibility of contact between the piston and any valves, the shape of the combustion chamber can be optimised for the effective mixing and combustion of the fuel/air mixture. n. The reduction in the number of component parts is estimated at between 60% and 70%, over a conventional engine. o. The elimination of castings for cylinder head and block, forgings for camshafts and crankshaft, belt and pulley drives, main bearing assemblies, bolting up, and inlet and exhaust manifolds, means that production costs of the engine will be substantially below those of conventional of the same power. Simplification of inlet and exhaust systems, reduction of fuel management to a single point injection for multiple cylinders, will make for further cuts in production cost and time.

With a three cylinder engine, three power pulses per revolution will increase power output over an equivalent four cylinder engine with 1/3rd more swept cylinder volume, by 50%.

With improved aspiration, it is anticipated that a three cylinder engine will provide double the power output of a conventional four cylinder engine of the same cylinder bore and stroke.

The gross weight of an engine should fall by about 50% for the same delivered power output (a power/weight increase of 100%). Further improvements in power/weight ratios, and unit power per unit of volume, and unit of swept cylinder capacity, appear possible.

The improved balance and anti-stall capacity of the engine should enable higher gearing and lower optimal engine speeds for a given power output, leading to much extended life.

The absence of reciprocating parts will make the engine low noise and exceptionally low vibration.

The engine has clear potential for significant improvement in thermal efficiency.

An embodiment of the present invention will now be described by way of an example only and with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional view through a three-cylinder rotary internal combustion engine in accordance with the present invention; Figure 2 is a perspective schematic view of a stator of the rotary internal combustion engine of Figure 1 ; and

Figure 3 is a schematic bottom view of the stator of figure 2.

Referring to the drawings, there is shown a rotary internal combustion engine comprising a stator 10 which defines a circular-section chamber 11 in which a rotor 12 is rotatably mounted. In the embodiment shown, the stator 10 is annular although it will be appreciated that the stator can be of any shape as long as the chamber 1 1 which it defines comprises an annular side wall.

The rotor 12 comprises an annular body 13 having a circular outer surface which has a diameter slightly less than the internal diameter of the chamber 1 1 , such that the rotor 12 can turn freely inside the chamber 1 1. Means (not shown) may be provided for applying lubrication between the inner surface of the chamber 1 1 and the outer surface of the rotor body 13.

The rotor 12 comprises three tubular piston barrels 14A, 14B, 14C which extend radially inwardly from the stator body 13 at respective circumferential positions, which are offset from each other by 120° and are disposed at the 0°, 120°, 240° positions shown in Figure 1. The barrels 14A, 14B, 14C define respective piston cylinders 15A, 15B, 15C which are open at their opposite ends. Pistons 16A, 16B, 16C are displaceably mounted inside the respective cylinders 15A, 15B, 15C for movement radially of the rotor body 13. The pistons 16A, 16B, 16C are connected via respective connecting rods 17A, 17B, 17C to a locus 18, which is eccentrically mounted in the central region of the chamber 1 1. The connecting rods 17A, 17B, 17C are of equal length and have a length such that the pistons 16A, 16B, 16C successively move between their radially outermost and innermost positions at the 0° and 180° positions respectively as they rotate.

Webs or braces 19 extend between the barrels 14 and the rotor body 13 to maintain the position of the barrels 14. The rotor body 13 and the barrels 14 may be formed as a one-piece member from steel or other material(s). An air inlet port 20 extends radially inwardly through the annular side wall of the chamber 11 from an air inlet duct (not shown). The air inlet port 20 is elongate and extends circumferentially of the annular side wall of the chamber 1 1 from approximately the 150° to the 245° positions shown in Figure 1. The width of the inlet port 20 increases gradually from the 150° to the 210° positions, at which point the width of the inlet port 20 remains constant to 245°.

A fuel injector and ignition port 21 extends radially inwardly through the annular side wall of the chamber 1 1 from a fuel injector and ignition unit 22.

An exhaust port 23 extends radially inwardly through the annular side wall of the chamber 1 1 from an exhaust outlet duct (not shown). The exhaust port 23 is elongate and extends circumferentially of the annular side wall of the chamber 1 1 from approximately the 130° to the 210° positions shown in Figure 1. The width of the outlet port 23 remains constant to 150°, at which point the width decreases gradually to the 210° position.

It will be appreciated that both the inlet and exhaust ports 20, 23 extend from the 150° to the 210° positions, with their width respectively increasing and decreasing. It will also be appreciated that the angular location, commencement and cessation of both ports 20, 23, and their overlap, may be varied widely.

The rotor body 13 is connected to a drive shaft (not shown), which extends axially out of the centre of the chamber 1 1 through an end wall or walls of the stator.

In use, the rotor 12 is rotated in the clockwise direction as shown by a starter motor. The cylinder 15C is full of clean air at the 240° position shown in Figure 1. Compression of the air commences once the cylinder 15C advances beyond the 240° position as it moves away from the inlet port 20 and the piston 16C moves radially outwards. Compression of the air is completed by the time the cylinder 15C has rotated to the 0° position shown in Figure 1. The fuel injector and ignition unit 22 comprises a fuel injector and a spark or glow plug (not shown). The operation of the fuel injector and ignition device can be electronically controlled so as to optimise their timing and duration in regard to operating conditions etc., as occurs in conventional internal combustion engines. Combustion proceeds as the cylinder 15C rotates from the ignition point, driving the piston 16C radially inwards and causing rotation of the rotor 13 until the cylinder 15C reaches the 120° position and the piston 16C is at its radially innermost position, whereupon the exhaust port 23 is exposed to the cylinder 15C. Between the 150° and the 210° positions, the cylinder 15C is exposed to both the inlet and exhaust ports 20, 23, so that pressurised air from the air inlet duct (not shown) can assist the scavenge process of the exhaust gas. Provision for exhaust gas recirculation (EGR) could be made also at this point.

Closure of the exhaust port 23 as the cylinder 15C rotates past the 210° position is followed by the full opening of the inlet port 20, whereupon the cycle completes and the process repeats until the engine stopped. Since there are three cylinders 15A, 15B, 15C at 120° from each other, there is always one cylinder in each stage (aspiration, combustion and exhaust) and the engine runs smoothly. Further or fewer cylinders may be provided.

Power is taken from the rotor 13 via the output shaft (not shown) to drive the machine or vehicle to which the engine is fitted.

A rotary internal combustion engine in accordance with the present invention is simple and inexpensive in construction yet provides numerous advantages over conventional internal combustion engines and Gnome type rotary internal combustion engines.

Claims

A rotary internal combustion engine comprising a stator having a stator body which defines a circular-section chamber in which a rotor is rotatably mounted for rotation about the axis of the chamber, the rotor comprising a radially- extending cylinder having an outer end in sealing but sliding contact with the inner surface of the annular side wall of the chamber, a piston displaceably mounted in the cylinder for movement axially of the cylinder and connected to a reaction point disposed eccentrically of the rotor, the stator having an ignition source, a fuel inlet port, an air inlet port and an exhaust port extending through the stator body into the chamber at respective circumferential positions for registering with the outer end of the cylinder at respective rotational positions thereof.

A rotary internal combustion engine as claimed in claim 1 , comprising a plurality of cylinders equally spaced around the circumference of the rotor.

A rotary internal combustion engine as claimed in claim 1 or claim 2, in which the ports are elongate and extend circumferentially of the annular side wall of the chamber.

A rotary internal combustion engine as claimed in claim 3, in which the air inlet and exhaust ports my partially co-extend over an angular region.

A rotary internal combustion engine as claimed in claim 3 or claim 4, in which an end of the inlet port is tapered.

A rotary internal combustion engine as claimed in any preceding claim, in which the air inlet port is at least equal in cross-sectional area to the bore of the cylinder.

A rotary internal combustion engine as claimed in claim 6, in which the air inlet port has a width which at least as wide as the diameter of the or each cylinder.

8. A rotary internal combustion engine as claimed in any preceding claim, arranged to apply lubrication between the inner surface of the chamber and the outer end of the or each cylinder.

9. A rotary internal combustion engine as claimed in any preceding claim, in which the rotor comprises a rotor body having a circular outer surface which has a diameter slightly less than the internal diameter of the chamber, such that the rotor can turn freely inside the chamber, the or each cylinder forming part of the rotor body.

10. A rotary internal combustion engine as claimed in any preceding claim, in which the tubular side wall of the stator comprises an annular ring.