GB2506893A

GB2506893A - Rotary radial two stroke internal combustion engine comprising intake and exhaust port timing control system

Info

Publication number: GB2506893A
Application number: GB201218249A
Authority: GB
Inventors: Tristan Peter Cooper
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-10-11
Filing date: 2012-10-11
Publication date: 2014-04-16
Also published as: GB201218249D0

Abstract

Disclosed is a rotary radial two stroke internal combustion engine including a fixed housing, a rotor and a crankshaft. Fixed air inlet and outlet ports are provided in the housing. The opening and closing timing of the inlet and outlet ports is controlled by the position of a piston located in a cylinder of the rotor and the position, size and shape of openings in the end of the fixed ports. Control of the opening and closing timing and the area of the inlet and outlet ports is achieved through the use of control discs located at an end of the ports. The discs are movable and disc has a circumferential or arcuate slot cut in to the disc. A pair of concentrically overlapping slotted discs may rotated relative to each other to vary the shape and size of the resulting slot and thus vary the shape, size and position that the fixed port presents to a cylinder of the rotary radial engine as the cylinder passes the ports. In this way the discs may be used to alter the timing for the opening and. closing of the ports while the engine is in operation.

Description

British Patent Application for "Improved Port Control in Rotary Radial 2 stroke Internal Combustion Engines" Applicant: Tristan Cooper f/a T Cooper Designs Application No: Filing Date: T Cooper Designs STAFFORD ROAD, CATERHAM, SURREY, CR3 6JE UK PHONE/FAX +44 (011883 345157 E-MAIL tcooperdeskrnst±maiI.com IMPROVED PORT CONTROL IN ROTARY RADIAL 2 STROKE INTERNAL COMBUSTION ENGINES.

Related documents U.S.A. PATENT DOCUMENTS 677,275 4/1976 Warwick, Douglas ROTARY ENGINE This invention relates to means for improving the opening and closing timing and area of inlet and exhaust ports in the cylinders of rotary radial two stroke internal combustion engines.

The present invention has resulted from a programme of design work seeking to produce a design of internal combustion engine in which the cylinders are disposed in a radial formation forming a rotating assembly or rotor. The working cycle of the engine is to be a two stroke type wherein there is one power or expansion stroke and one compression stroke for each single rotation of the rotor. This combination of the two stroke cycle with a rotating rotor allows for greater control of the inlet and exhaust port timing than is normal for a conventional two stroke engine. In this invention, it will be shown that by the use of certain additional components, further control of the port timing may be achieved. Considerable improvement in the total engine efficiency will result through the incorporation of these components with resultant increased engine specific power output, lower specific fuel consumption and wider engine power range.

A rotary radial engine may comprise any number of cylinders from one upwards.

These cylinders may be disposed in a radial formation about a centre point, with a big end bearing suitably offset from the cenne, thus forming the rotor. Connecting rods radiating from the big end bearing will be connected to circular pistons which operate within the cylinders. See Figure 1.

Inlet and exhaust ports for each cylinder may be positioned in the faces of the rotor such that induction air is received by the pistons from one end of the engine while exhaust gases are ejected from the other end. See Figure 2.

It is normal in a two stroke engine for the timing of the opening of the inlet and exhaust ports to be under the control of the piston such that the side of the piston closes the ports until either the top or the bottom of the piston clears the port and allows it to open. However, in the proposed design, the inlet and exhaust ports in the rotor will communicate with stationary openings in the ends of the engine. The size, shape and position of these stationary openings will further affect the opening and closing timing of the ports in addition to that timing as dictated by the piston. See Figures 3a &3b.

The additional components mentioned above may be in the form of simple movable flat discs employed to provide variable control of the aforementioned port timing. By using two discs for each stationary opening, see Figure 4, the following control may be achieved in additional to that dictated by the size and position of the stationary openings: delayed opening of the inlet port -reducing loss of inlet air into the exhaust; advanced closing of the inlet port -reducing back-flow of inlet air at low speeds; delayed opening of the exhaust port -increasing the expansion of the charge; advanced closing of the exhaust port -reducing loss of inlet air into the exhaust.

Fig 1 -a rotary radial engine showing the rotor end view Fig 2 -a rotary radial engine showing the rotor side view Figs 3a & 3b -showing the influence of the stationary openings Fig 4 -discs to provide increased port timing control There is no limit to the number of cylinders that may be used in a rotary radial two stroke. Each cylinder will achieve its full cycle of induction, compression, expansion and 20. . . . . exhaust within a single rotation of the rotor. Consequently, as every cyhnder will produce power for every rotor rotation, both odd and even numbers of cylinders will provide a smooth production of power output. A four cylinder construction is used here for illustration.

In a two stroke engine, a means of forcing air into the cylinders is required as there is no distinct induction stroke as found in a four stroke engine type. Many small two stroke engines use the crankcase as an air pump. Air and a fuel and oil mixture pass into thc crankcasc as the piston riscs in thc cylinder. As thc piston descends, this mixturc is compressed and passes into the upper part of the cylinder through transfer ports that are under the control of the piston. It is nccessary to add oil to the inducted air and fuel mixture as a means of lubricating the bearings and cylinder walls. This results in the constant loss of lubricant as this oil passes into the combustion space and thence to the atmosphere. There are three undesirable results from loss of oil: a! burnt oil is a significant pollutant, producing smoke, smell and a health risk; b! oil has the effect of reducing the octane rating of the fuel causing an increased risk of pre-ignition or detonation; c/oil burning in the cylinder can cause the formation of deposits on the spark plug resulting in lack of or erratic ignition; deposits on the piston crown, cylinder head and ports can further affect engine efficiency.

In a rotary radial two stroke engine, the volume of the crankcase is not changing significantly during thc cnginc's cyclc and thcrcfore thc crankcase cannot bc used for thc induction of air. A scparate means must thereforc be providcd to pump air into the cylinders. This means may be by a variety of air pumps as preferred by the designer and is not critical to the design described here. However, because the crankcase is not used as an air pump in the proposed design, lubricating oil can be used within the crankcase withrnit the risk of loss of said oil into the combustion space. All the undesirable side-effects of a constant loss oil system as described above are therefore eliminated.

In the proposed design, the inlet and exhaust ports of each cylinder will be controlled by: a! the pistons; b/ stationary openings in the engine housings; c/ movable discs positioned in the vicinity of the stationary openings so that the following may take place: Inlct and exhaust port control: The rotor is contained within a housing that abuts the faces of the rotor. Inlet and exhaust openings are contained within the housing such that air flows into one end of the engine and exhaust exits through the other end.

With reference to Figure 3a, with the piston 10 at position "a", the exhaust port 9 is doscd by thc piston. As thc rotor turns, the piston movcs away from thc port until thc port is fully open at "b" and the port also is aligned with the stationary opening 8 so that the exhaust function may take place. When the piston has reached "c" the piston is still allowing the exhaust port to be open but the port is no longer aligned with the stationary opening so that the exhaust port is effectively closed. This differs from a conventional 2 stroke engine where the piston only dictates the open or closed state of the port.

With reference to Figure 3b, the inlet port will be allowed to open by the piston before position "d" is reached but the inlot port is not aligned with the stationary opening and therefore the inlet function has not yet started. As the piston moves beyond position "d" the inlet port aligns with the stationary opening and the inlet function begins. At positioll "c" thc inlet port is approaching the end of the stationary opening and the inlet function is about to stop. At position "f" the inlet port is fully closed.

With the stationary openings as shown in Figures 3a & 3b, thc opcning and closing timing of the inlet and exhaust ports is determined by the placement of the moving ports in relation to the piston position and also by the size, shape and position of the stationary openings. At different engine rotation speeds, it is desirable to be able to vary the point at which the inlet and exhaust functions may start and finish. The purpose of this invention is to provide a means of effectively varying the size, shape and position of the stationary openings as can be seen in Figure 4.

Between the rotor faces and the housing there may be one or two movable discs which provide the additional control of the ports. See Figure 4 discs: II. By rotating these discs relative to each other and to the stationary openings, the inlet and exhaust openings may be increased or decrcascd in sizc. Further, the rotational point at which each rotor port conmiunicates with the opening may be varied thereby affecting the timing of the point at which the port opens or closes. With reference to Figure 4, two thin metal discs 11 are shown with their openings 12 as shown at "g" & "h". Figure 4 "F' shows the two discs superimposed on each other and rotated so that only a small opening is created.

This will produce a very limited inlet or exhaust function as may be desirable under low engine load conditions. Figure 4 "j" shows the two discs superimposed but rotated so that a large opening is availab'e to the inlet or exhaust ports so increasing the time availabk for the inlet and exhaust function to take place thus causing the engine to produce a higher power output.

Claims

CLAIMS1. A means of controlling the exhaust gas outflow from an internal combustion rotary radial engine resulting in improved engine efficiency.
2. A means of controlling the inlet gas inflow into an internal combustion rotary radial engine resulting in improved engine efficiency 3. A means as claimed in Claim I and Claim 2 where that means is applied to an engine using a rotatable disc or discs..4. A means of improving the exhaust gas outflow and inlet gas inflow to an internal combustion engine substantially as described above and illustrated in the accompanying drawings.CLAIMS1. A means of controlling the exhaust gas outflow from an internal combustion rotary radial engine resulting in improved engine efficiency.this invention therefore relates to a two-stroke rotary radial internal combustion engine comprising a housing, a rotor which rotates within the housing and a stationery crankshaft, the main axis of the crankshaft defining a centre point about which the rotor rotates.the housing comprising one or more fixed inlet ports at one end of the housing and one or more fixed outlet ports at another end of the housing.the rotor comprising at least one cylinder disposed in a radial formation about the crankshaft and a CO piston operating within the cylinder, a connecting rod which connects the piston to the crankshaft by a big end bearing which is offset from the central axis of the crankshaft, an inlet port which allows intake of air in to the cylinder as the cylinder passes the fixed inlet port in the housing and an 0 outlet port for ejecting exhaust gases thm the cylinder when the cylinder passes the fixed outlet ___ port in the housing.wherein one or more rotatable flat discs, concentric with the crankshaft centre, are positioned to at least partly cover each of the fixed openings in the housin& each flat disc having a slot cut in to a segment of the disc so that when the disc is rotated it provides varying degrees of obstruction of the fixed port and thus varies the size and position of an opening presented to the rotor cylinder as it passes the fixed ports thus providing a means of controlling the timing and duration of the opening and closing of the inlet and exhaust ports.2. Ameans as claimedinClaim 1 wherethatmeans is appliedto anengineusing arotatable disc or discs..
3. A means of improving the exhaust gas outflow and inlet gas inflow to an internal combustion engine substantially as described above and illustrated in the accompanying drawings.