GB2144489A

GB2144489A - Rotary internal-combustion engine

Info

Publication number: GB2144489A
Application number: GB08320925A
Authority: GB
Inventors: Geoffrey Fawn
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-08-03
Filing date: 1983-08-03
Publication date: 1985-03-06
Also published as: GB8320925D0

Abstract

The engine may be of the Wankel type (as shown) and has a pair of rotors 10, 110 and ducts 24, 25 through which a proportion of the fuel-and-air mixture is transferred from each rotor chamber to the other, the transferred mixture being partially compressed. The performance of the engine when idling is thereby improved. Valves 26, 27 may be incorporated in the ducts and be closed when the engine speed exceeds a selected limit eg. 1000 r.p.m. Ports through which the transferred mixture enters the rotor chambers may be situated between the inlet and exhaust ports 19, 20 and 119, 120. <IMAGE>

Description

SPECIFICATION Rotary engine The present invention relates to a rotary internal combustion engine comprising at least one pair of rotors in respective cavities, each rotor contacting the peripheral boundary of its cavity at a plurality of positions and there being defined between the rotor and the boundary of its cavity a corresponding number of working chambers, the volume of which varies as the rotor moves in its cavity. Each cavity of a rotary internal combustion engine has an inlet port which communicates with each working chamber during an induction phase of a cycle of the engine with respect to that chamber and an exhaust port which communicates with each working chamber during an exhaust phase of the cycle with respect to that chamber. An example of a rotary internal combustion engine is a Wankel engine. The engine may comprise two or more pairs of rotors.

During a cycle of the engine, each working chamber undergoes an induction phase, during which a charge of air and fuel is drawn into the chamber, a compression phase, during which the charge is compressed, an expansion phase, during which the charge burns and an exhaust phase, during which the products of combustion leave the working chamber through the exhaust port.

According to one aspect of the present invention, a rotary internal combustion engine having a pair of rotors in respective cavities comprises a pair of ducts, each duct leading from a working chamber associated with one rotor when that working chamber undergoes the compression phase to a working chamber associated with the other rotor.

It has been discovered that, with the two rotors connected together 1 80 out of phase, idling of the engine is improved by the present invention.

Each cavity preferably has an injection port at which the duct from the other cavity terminates, the injection port opening either into the inlet port of the cavity or into each working chamber of that cavity when the working chamber undergos the exhaust phase and/or the induction phase.

The injection port preferably lies within a sector defined by respective planes containing a central axis of the cavity and passing one through the extremity of the inlet port furthest from the exhaust port and the other through the extremity of the exhaust port furthest from the inlet port.

There may be provided, for each cavity, an outlet port which lies further from the inlet port than does the injection port of that cavity, each duct leading from the outlet port of a respective cavity to the injection port of the other cavity.

There may be provided in each duct a valve for closing the duct when the engine is required to operate under substantial load and/or at high speed.

According to a further aspect of the invention, there is provided a method of operating a rotary internal combustion engine comprising a pair of rotors in respective cavities, wherein, during compression of a charge of fuel and air in a working chamber in one of said cavities, a part of the charge is permitted to flow from the one cavity towards or into a working chamber in the other cavity.

It is preferred that the flow of charge be permitted during a first part of the period during which the charge is subjected to compression and this part may be approxiamtely one half of the period.

Two examples of engines embodying the invention will now be described, with reference to the accompanying drawings, wherein: Figure 1 shows a diagrammatic representation of a first rotary engine, and Figure 2 shows a diagrammatic representation of a second rotary engine.

The engine illustrated in Fig. 2 has a first rotor 10 which, as viewed in a direction along its axis of rotation, has a shape approximating to that of an equalateral triangle. Each side of the triangular shape is formed by a convex face, 11, 1 2 and 1 3 respectively. The rotor has substantially flat ends which are perpendicular to the axis of rotation and one of which is shown at 14. The rotor 10 is disposed in a two-lobed epitrochoidal cavity defined by a housing 10 which includes a middle member defining the peripheral boundary of the cavity and end plates defining opposite end boundaries of the cavity adjacent to the end faces of the rotor.Seals are provided in the end faces of the rotor to engage the end boundaries of the cavity and the rotor is further provided with apex seals, each of which remains in contact with the peripheral wall of the cavity so that there is defined between the rotor and the housing three working chambers 16, 1 7 and 18 respectively. The rotor 10 rotates about its own axis and also moves eccentrically in the cavity in such a manner that the volume of each of the working chambers varies during each cycle of rotation of the rotor.

There is formed in the middle member of the housing 1 5 an exhaust port 1 9 and an inlet port 20 spaced somewhat along the periphery of the cavity from the exhaust port in the direction of rotation of the rotor. In the case of a spark ignition engine, a sparkplug 21 is mounted in the housing at a position remote from both of the exhaust port and inlet port. There is also formed in the housing 1 5 an injection port 22 and an outlet port 23.

The injection port is disposed between the exhaust port 1 9 and the inlet port 20, in the particular example shown in Fig. 1, being somewhat nearer to the exhaust port than to the inlet port. The outlet port 23 is disposed between the inlet port 20 and the sparkplug 21, being spaced somewhat further from the inlet port than is the injection port 22. With the exception of the injection port 22 and the outlet port 23, the assembly of housing 1 5 and rotor 10 is constructed and arranged in a known manner.

The engine of Fig. 1 further comprises a second rotor 110 in a cavity defined by a housing 11 5. This rotor and housing are identical with the rotor 10 and housing 1 5 respectively and parts of the second rotor and housing are identified by like reference numerals with the prefix 1. The rotors 10 and 110 wouid normally be arranged end-to-end on a common shaft but, for the purpose of illustration, are shown side by side in Fig. 1. The rotors are connected together by the common shaft and are 180 out of phase.

A duct 24 leads from the outlet port 1 23 of the second housing to the injection port 22 of the first housing. A corresponding duct 25 leads from the outlet port 23 of the first housing to the injection port 1 22 of the second housing. Valves 26 and 27 are provided in the ducts 24 and 25 respectively, these valves being open when the engine is idling and being closed by speed-responsive means (not shown) when the engine speed rises substantially above idling speed, for example above 1,000rpm. Each valve may be arranged to be either fully open or fuily closed. Alternatively, each valve may be arranged to close progressively as the engine speed and/or engine load increases.

The operation of the rotors 10 and 110 is the same and therefore operation of the rotor 10 only will be described. With the rotors in the position shown in Fig. 1, the working chamber 1 6 associated with the rotor 10 is in communication with the inlet port 20 and is in an induction phase. A charge of air and fuel is drawn through the inlet port into the working chamber 1 6 as it rotates in a clockwise direction through the position of Fig. 1. When the apex seal at the trailing boundary of the working chamber 1 6 passes the inlet port 20, the chamber 1 6 commences its compression phase. During the compression phase, the volume of the chamber 1 6 decreases and the charge is compressed.

However, if the valve 27 is open, a part of the charge is permitted to bleed away from the chamber 1 6 through the outlet part 23 to the working chamber 11 7 associated with the second rotor, via the injection port 1 22. The working chamber 1 6 communicates with the outlet port 23 from the beginning of the compression phase for a part only of the compassion phase of the working chamber 1 6. Before the charge in that chamber is fully compressed, communication with the outlet port 23 is terminated as the apex seal at the downstream end of the chamber 16 passes the outlet port.

As the working chamber 16, containing compressed charge, passes the sparkplug 21, the charge is ignited and the charge expands as the chamber 1 6 moves away from the sparkplug. The expansion phase is completed when communication is established between the working chamber 1 6 and the exhaust port 1 9. The products of combustion then leave the working chamber through the exhaust port.Shortly after communication between the working chamber 1 6 and the exhaust port 1 9 is established, communication is established between the injection port 22 and the chamber 1 6. Provided the valve 26 is open, flow of charge from a working chamber associated with the second rotor 110 into the working chamber 1 6 then commences. It is believed this charge displaces from the working chamber 1 6 products of combustion which would otherwise remain in that working chamber.

The working chambers 1 7 and 18 associated with the first rotor 10 undergo the same phases as does the working chamber 16.

Each of the working chambers associated with the second rotor 110 also undergoes the same phases. Charge flows intermittently from the working chambers associated with each rotor to the working chambers associated with the other rotor when the valves 26 and 27 are open. It has been found that injection and outlet ports and pipework connected therebetween having an internal diameter of approximately 3mm provides satisfactory results.

The flow through these ducts may be restricted by means of the valves.

The engine illustrated in Fig. 2 comprises first and second rotors 210 and 310, which may be identical with the rotor 10, operating in cavities defined by respective housings 21 5 and 315. With the exception of the positions of the injection ports 222 and 322 and outlet ports 223 and 323, the housing 215 and 315 may be identical with the housing 15.

The first and second rotors of the engine shown in Fig. 2 are connected together 180 out of phase, in the same manner as the rotors of the engine illustrated in Fig. 1 and the working chambers undergo the same phases of operation as hereinbefore described.

In the engine shown in Fig. 2, the injection port 222 leads into the inlet port 220, preferably at a position near to the peripheral boundary of the cavity defined by the housing 215. The injection port 322 is similarly positioned in the inlet port 320. The outlet port 223, which is connected by a duct 225 with the injection port 322, may occupy the same position with respect to the inlet and exhaust ports of its housing, as does the outlet port 23 with respect to the ports 1 9 and 20. The outlet port 323 associated with the second rotor of the engine of Fig. 2 is connected by a duct 224 with the injection port 222 associated with the first rotor.Other parts of the engine shown in Fig. 2 which correspond with parts of the assembly of rotor 10 and housing 1 5 are indicated by like reference numerals with the prefix 2, in the case of the first rotor and housing, and by the prefix 3, in the case of the second rotor and housing. The ducts 224 and 225 are preferably provided with valves corresponding to the valves 26 and 27 of the first engine.

The positions of the injection ports may be varied from those shown in Figs. 1 and 2.

Preferably, each injection port lies either between the exhaust port and inlet port or within the inlet port. The position of each outlet port also may be varied from the position shown in the drawings, by increasing or decreasing the distance between the outlet port and the inlet port. However, we prefer that the outlet port should be further from the inlet port than is the injection port. At all speeds of operation of the engines illustrated, the working chambers associated with both rotors are charged with air and fuel which is burned. Whilst both the outlet port and the injection port associated with each rotor are conveniently formed in the middle component of the associated housing, one or both ports could be formed in a further component of the housing.

Claims

1. A rotory internal combustion engine having a pair of rotors in respective cavities comprises a pair of ducts, each duct leading from a working chamber associated with one rotor when that working chamber undergoes the compression phase to a working chamber associated with the other rotor.

2. An engine according to Claim 1 wherein the two rotors are connected together 180 out of phase.

3. An engine according to Claim 1 or Claim 2 wherein each cavity has an injection port at which the duct from the other cavity terminates, the injection port opening into the inlet port of the cavity.

4. An engine according to Claim 1 or Claim 2 wherein each cavity has an injection port at which the duct from the other cavity terminates, the injection port opening into the cavity in the region where each working chamber undergoes the exhaust phase.

5. An engine according to Claim 1 or Claim 2 wherein each cavity has an injection port at which the duct from the other cavity terminates, the injection port opening into the cavity in the region where each working chamber undergoes the induction phase.

6. An engine according to any one of the preceding claims wherein the injection port lies within a sector defined by respective planes containing a central axis of the cavity and passing one through the extremity of the inlet port furthest from the exhaust port and the other through the extremity of the exhaust port furthest from the inlet port.

7. An engine according to any one of the preceding claims wherein there is provided, for each cavity, an outlet port which lies further from the inlet port than does the injection port of that cavity, each duct leading from the outlet port of a respective cavity to the injection port of the other cavity.

8. An engine according to any one of the preceding claims wherein there is provided in each duct a valve for closing the duct.

9. An engine substantially as hereinbefore described with reference to and as shown in Fig. 1 or Fig. 2 of the accompanying drawings.

10. A method of operating a rotary internal combustion engine comprising a pair of rotors in respective cavities, wherein, during compression of a charge of fuel and air in a working chamber in one of said cavities, a part of the charge is permitted to flow from the one cavity towards or into a working chamber in the other cavity.

11. A method according to Claim 10 wherein the flow of charge is permitted during a first part of the period during which the charge is subjected to compression in said one cavity.

1 2. A method according to Claim 11 wherein said portion is approximately one half of the period.

1 3. A method according to any one of Claims 10 to 1 2 wherein said part of the charge is permitted to flow into the inlet port of the other cavity.

14. A method according to any one of Claims 10 to 1 2 wherein said part of the charge is permitted to flow into a working chamber when the working chamber undergoes the exhaust phase.

1 5. A method according to any one of Claims 10 to 12 wherein said part of the charge is permitted to flow into a working chamber when the working chamber undergoes the induction phase.

16. A method of operating a rotary internal combustion engine substantially as hereinbefore described with reference to Fig. 1 or Fig. 2 of the accompaning drawings.

1 7. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.