WO1992003645A1

WO1992003645A1 - Variable flow gas passages

Info

Publication number: WO1992003645A1
Application number: PCT/AU1991/000375
Authority: WO
Inventors: Arthur James Fahy
Original assignee: Fahy Arthur J
Priority date: 1990-08-22
Filing date: 1991-08-21
Publication date: 1992-03-05

Abstract

In a two-stroke cycle engine (30) the walls (43) of the transfer port duct (39) are made of a resilient material with incorporated cavities (44). The volume of a fluid within the cavities (44) is varied to alter the shape of the duct walls (43) and hence the cross-sectional area of the duct (39) in accordance with engine operating parameters. Means are also disclosed for varying the area and timing of the port opening (40) and various non-resilient means for varying the cross-section of two-stroke transfer ducts. There is also disclosure of over-head valve engine embodiments having inlet ducts with deformable resilient walls.

Description

VARIABLE FLOW GAS PASSAGES

The present invention relates to the gas transfer ports of internal combustion engines.

Background - Prior Art

The intake ports of internal combustion engines are tuned to the operating speed of the engine. A port which is tuned for low speeds of operation is most unsuitable for high speed operation. The converse is true for ports designed for high speed operation. When an engine operates at high speeds, the gas flow is considerably greater than that at low speeds.

In two stroke engines, the above problem is exacerbated, since the crank case is used to transfer the air, or air and fuel mixture, to the combustion chamber.

The angle at which gases enter the combustion chamber, also influences the efficiency of the engine. The angle of the direction of movement of the gas at the inlet openings is designed for particular operating speeds. Accordingly a particular port opening does not suit the full range of operating speeds of a two stroke engine, particularly if the engine has a wide range of operating speeds. Examples of Prior Art

Examples of prior art constructions for internal combustion engines for controlling the flow of gases in the inlet or exhaust port passages are disclosed in the following patents.

Patentee Patent No. Issue Date

Nerstrom U.S. 4,516,540 May 14, 1985

Meulien U.S. 2,714,879 Aug 9, 1955

McGabe U.S. 1,743,558 Jan 14, 1930

Garve U.S. 2,189,106 Feb 6, 1940 Baumhardt U.S. 4,549,507 Oct 29, 1985

Stil U.S. 1,514,476 Sept 1, 1921

Cook U.S. 29,449/71 May 31, 1971

Group Lotus PLC Austral. 34872.89 May 17, 1989

It is the object of the present invention to overcome or substantially ameliorate the above disadvantages.

There is disclosed herein an internal combustion engine port assembly comprising:

A body providing a port chamber to communicate with a combustion chamber of said engine, said port chamber having an inlet and an outlet; and

Means mounted internally of said body and co-operating with said port chamber to provide a port duct through which gas flows from said inlet to said outlet, and wherein said means at least partly defines a wall surface of said duct along a significant length thereof, and is deformable to vary the cross-sectional area of said duct at said means to effectively alter the velocity of gases passing there through.

There is further disclosed herein an Internal combustion engine port assembly comprising: a body providing at least two inlet port chambers to communicate with a combustion chamber of said engine, said port chamber terminating at an Inlet opening for said combustion chamber, which Inlet opening directs gases Into said combustion chamber; and means to alter the configuration of said opening to alter the direction of movement of the gases from said opening into said combustion chamber. iσ There is still further disclosed herein an Internal combustion engine port assembly comprising: a body providing at least two port chambers which communicate with a combustion chamber of the engine, which port chambers provide for gases to be delivered to or gases to be ducted from said combustion chamber; and iS means to selectively close at least one of said port chambers-

Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

Figure 1 is a schematic section side elevation of the piston cylinder and port assembly of an Internal combustion engine; 2.0 Figure 21s a schematic section side elevation of the piston cylinder and port assembly of Figure 1 in a further operative mode;

Figure 3 is a schematic section side elevation of a two stroke engine;

Figure 4 is a schematic side elevation of the engine of Figure 1, 1n a further operative mode; $ Figure 51s a schematic side elevation of a modification of the piston cylinder and port assembly of Figure 1;

Figure 61s a schematic side elevation of the piston cylinder and port assembly of Figure 5 in a further operative mode;

Figure 7 is a schematic top plan view of a combustion chamber for a two stroke Internal combustion engine;

Figure 81s a schematic side elevation of a two stroke internal combustion engine;

Figure 9 is a schematic side elevation of the engine of Figure 8; 5" Figure 101s a schematic section side elevation of a still further two stroke Internal combustion engine;

Figure 11 is a schematic side elevation of the engine of Figure 10;

Figure 121s a schematic part section top plan view of the combustion chamber of a two stroke Internal combustion engine; and ιo Figure 13 is a schematic part section side elevation of the engine of

Figure 12.

In Figures 1 and 2 there is schematically depicted a port assembly 10 of an internal combustion engine having a cylinder 11 with which there co-operates a piston 12. The cylinder 11 and piston 12 co-operate with a IS cylinder head body 13 to provide a combustion chamber 14. Air and fuel are delivered to the combustion chamber 14 to be ignited to produce a gas under pressure to drive the piston 12. Communicating with the combustion chamber 14 are port ducts 15 and 16. The ducts 15 and 16 have valve seats 17 enclosing a valve opening 18 opened and closed by reciprocated valve HP membe , 19.

The body 13 provides port chambers 20. Mounted 1n each chamber 201s a defor able diaphragm member 21 which 1s elastically deformable to vary the cross-sectional area of the duct 16 at the location of the member 21. Each member 21 encloses a cavity 22 which receives a fluid. The pressure 2.S within the fluid governs the degree by which the member 21 extends into the duct 16 to reduce the cross-sectional area thereof. Each cavity 22 would have leading from it a conduit 23 which communicates with a supply of fluid under pressure. This supply would govern the pressure within each cavity 22 and therefore the cross-sectional area of the duct 16 at the member 21. The cross-sectional area 1n turn could be regulated to the speed of the engine and the throttle setting. At low speeds of operation, that is low gas flows, the cross-sectional area of the duct would be reduced as shown in Figure 2. At higher speeds and higher gas flows, the cross-sectional area of the duct 16 would be increased.

In the above described preferred embodiment, it should be appreciated that the deformable members 21 could be applied to both Inlet and outlet

\ o ducts 15 and 16.

As a modification of the above described assembly 10, the deformable members 21 to be mechanically moved via a cam operation or similar type mechanical system. As a still further alternative, each member 21 could be embedded with iron powder. The shape of the member 21 could then be iS controlled by an electro-magnetic field produced by an electro-magnet 24 as best seen in Figures 5 and 6. The magnet 24 will receive an electric current via electric leads 25. With the duct 16 having a maximum cross-section, the magnets 24 could be de-energised. As an electric current 1s delivered thereto and the magnetic field builds up, the members

2_> 22 to be deformed to reduce the cross-sectional area of the duct 16. This 1s best seen in Figure 6.

In Figures 3 and 4, there is schematically depicted a two stroke engine 30. The two stroke engine 30 has a cylinder member 31 co-operating with a piston 32 and cylinder head 33 to provide a combustion chamber 34.

2.5 Mounted 1n the head 33 1s a spark plug 35 which ignites the air fuel mixture. The piston 32 is attached to a crank shaft 36 which is caused to rotate. Enclosing the crank shaft 36 and lower portion of the engine 30 is a crank case 37. The crank case 37 encloses a crank case chamber 38 to which the air fuel mixture is delivered. The chamber 38 communicates with the chamber 34 via a port duct 39. Reciprocation of the piston 32 alters the volume of the chamber 38, to cause transfer of fuel to the chamber 32 via the port duct 39. The port duct 39 has an outlet opening 40.

Extending from the chamber 34 is an outlet port 41. Normally the 5 outlet port 41 would be displaced 90° about the longitudinal axis of the cylinder 31 from the port 39. For ease of Illustration, the port 41 1s Illustrated as opposing the opening 40.

The crank case 37 or other portion of the engine, provides a port chamber 42 within which there 1s mounted a deformable member 43 providing lo at least a portion of the wall surface defining the port duct 39. The member 43 has cavities 44 to which a fluid under pressure 1s delivered to deform the member 43 to vary the cross-sectional area of the duct 39 at the member 43. The cavities 44 communicate with a conduit 45 to which the fluid under pressure is delivered to alter the cross-sectional area of the IS port duct 39. Accordingly, the cross-sectional area of the port duct 39 can be changed to match the operating speed and gas flows to maximise the efficiency of the engine 30.

As a modification of the engine 30, the conduit 45 could be attached to a bladder 46 which 1s exposed to atmospheric pressure. The flexibility 2.0 of the member 43 could be arranged so that the member 43 Is deformed as a result of the pressure within the port duct 39. As pressure builds up, fluid will be transferred from the cavities 44 to the bladder 46. At low operating speeds, with a low pressure in the duct 39, the bladder 46 would automatically transfer fluid back to the cavities 44 to reduce the 2.5 cross-sectional area of the duct 39, as best Illustrated in Figure 4.

If so required, it may also be advantageous to provide as an adjunct to or as a separate entity, a port defining body 47 which co-operates with the member 43 to alter the cross-sectional area of the opening 40. At low speeds, the opening 40 would have a small cross-sectional area. At higher operating speeds, and higher gas flows, the opening 40 would be Increased in area. Still further, by movement of the body 47, the time at which the opening 40 Is exposed by the piston 32 can be altered. This will further aid 1n optimising the efficiency of the engine. As the engine speeds 5" decrease, the opening 401s exposed at a later time during the cycle. As the engine speed increases, the opening 40 is exposed sooner.

In Figure 7 there 1s schematically depicted an Internal combustion engine 50. The engine 50 is a two stroke engine and is provided with a combustion chamber 51. Communicating with the combustion chamber 51 are IO Inlet ports 52 and an outlet port 53. Each of the inlet ports 52 provides an Inlet opening 54 which Is at least partly defined by a deformable diaphragm 55. The diaphragm 55 is formed with cavities 56 and 57 which receive liquid under pressure from conduits 58 and 59. By altering the various sizes of the cavities 56 and 57, the direction 60 of the movement

IS of the gases exiting via the openings 54 may be altered. For example, the cavity 56 may be enlarged so as to be larger than the cavity 57 or alternatively the cavity 57 enlarged so as to be greater than the cavity 56. Accordingly, the volume of the cavities 56 and 57 may be altered to change the configuration of the openings 54 to change the directions 60.

2.0 The volumes of the cavities 56 and 57 can be altered in accordance with engine speeds and/or throttle openings.

In Figures 10 and 11 there is schematically depicted an internal combustion two stroke engine 70 having an inlet port assembly 71. The Inlet port assembly 71 communicates with the combustion chamber 72 when the

ZS piston 73 Is towards the bottom of its stroke. The port assembly 71

Includes a movable port defining member 74 which Is movable between a first position (Figure 10) and a second position (Figure 11). In the first position, the member 74 maximises the volume of the port chamber 75, while in the position as shown In Figure 11, the member 74 minimizes the volume of the port chamber 75.

The member 74 Includes a first Up 76 which co-operates with a curved portion 77. The other end of the member 74 Is provided with a flange 78 which alters the height of the inlet opening 79 in accordance with movement 5 of the member 74.

The member 74 is pivoted by means of a pivot mounting 79 which enables movement of the member 74 to adjust to the pressure within the chamber 75. Engaging the member 741s a spring 80 which in conjunction with the pressure of the gas within the chamber 75, adjusts the position of IO the member 74.

In Figures 8 and 9 of the accompanying drawings there 1s schematically depicted an internal combustion engine 90. The engine 90 has an inlet port assembly 91 which Includes a sϋdable wall 92 which is movable to adjust the volume of the Inlet port chamber 93. The wall 92 may tS be moved 1n unison with the throttle opening and/or the engine speed. The wall 92 sealingly co-operates with Internal surfaces 93, and has a flap 94 which aids 1n the smooth transfer of gases from the crank case 95 to the chamber 93. The flap 941s pivotally attached to the wall 92 at the pivot assembly 96. 2o Part of the wall 92 engages a member 97 which at least partly defines the Inlet opening 98. Movement of the wall 92 causes movement of the member 97 to alter the effective height of the opening 98. Still further, movement of the member 97 will govern the position at which the piston 99 exposes the opening 98 to the combustion chamber 100. 2.5 In Figures 12and13 there is schematically depicted a two stroke

Internal combustion engine 110. Engine 110 has a cylinder member 111 co-operating with a piston 112 and cylinder head 113 to provide a combustion chamber 114. Mounted 1n the head 113 is a spark plug 115 which ignites the air fuel mixture. The piston 112 is attached to a crank shaft 116 which 1s caused to rotate. Enclosed 1n the crank shaft 116 and lower portion of the engine 1101s a crank case 117. The crank case 117 encloses a crank case chamber 118 to which the fuel air mixture 1s delivered. The chamber 118 communicates with the combustion chamber 114 via port ducts 5 119. Reciprocation of the piston 112 alters the volume of the chamber 118 to cause transfer of the fuel air mixture to the combustion chamber 114 via the port ducts 119. The port ducts 119 have outlet openings 120 and Inlet openings 127. The cylinder member 111 has an exhaust port 125. The crank case 117 or Inlet duct 121 provides a means to mount a guillotine type to slide 122, slidable in guides 123 by a rod 124 in two of the port ducts 119 out of the four port ducts 119 shown.

Occasionally the slide 122 can close off a port 119 so that no gas can flow from the crank case chamber 118 to the combustion chamber 114 through the port 119. This decreases the effective volume and cross

IS sectional area of the inlet ducts 119.

Conversely, the slide 122 can open up a port 119 thereby increasing the effective cross sectional area of the port ducts 119 to provide optimum gas velocity with a given volume of gas delivered to the chamber 114.

2.0 As shown in Figure 13., two of the four Inlet port ducts 119 can be closed off when the engine 110 reaches a relatively low angular velocity, to thereby decrease the effective volume and cross sectional area of the inlet port 119. This increase in the velocity of gas delivered Into the combustion chamber 114 maximises the efficiency of the engine 110 at S relatively low angular velocities. On the other hand, if the ports 119 are open to maximise cross sectional area, the efficiency of the engine 1s increased at high angular velocities.

The slides 122 can be controlled by the voltage generated by the engine's electric generator or other characteristic which is dependant on the rotational speed of the engine.

The slides 122 can be controlled by the crank case pressure, the higher the crank case pressure the more the slides 122 are opened.

The slides 122 are Ideally located at the inlet end 127 of the port duct 119 to minimize the effective volume of the crank case chamber 118.

Claims

The claims defining the invention are as follows:

Claim 1. An internal combustion engine port assembly comprising a body providing a port chamber to communicate with a combustion chamber of said engine, said port chamber having an inlet and an outlet, and means mounted internally of said body and co-operating with said port to provide a port duct through which gas flows from said inlet to said outlet and wherein said means at least partly defines a wall

_ o surface of said duct along a length thereof, and is deformable to vary the cross-sectional area of said duct at said means, to effectively alter the velocity and angle of entry of gases into the combustion chamber.

Claim 2. A port assembly of Claim 1. wherein said port duct is in 5 a two stroke engine and is deformable to alter the height of the port outlet opening.

Claim 3. A port assembly of Claim 1. wherein said port duct wall surface is made of a suitable material such as rubber and is deformed by an increase or decrease of fluid O volume in a chamber or chambers behind the walls of said port duct.

Claim 4. A port assembly of Claim 1. wherein said duct deformable wall surface is moved mechanically by means of a cam or other mechanical means.

S Claim 5. A port assembly of Claim 1. wherein said deformable wall surface of said port duct is moved by magnetic force.

Claim 6. A port assembly of Claim 1. wherein a substantial part of the wall of said duct is automatically moved by gas 0 pressure inside the duct

Claim 7. A port assembly of Claim 1. wherein said port duct wall has Iron particles or magnetic material within its structure that is acted upon by the magnetic field of an electro-magnet.

Claim 8. A two stroke Piston Ported internal combustion engine port assembly comprising a body providing at least two port chambers which communicate with a combustion chamber of the engine, which port chambers provide for gases to be delivered to said combustion chamber,

J O and means to selectively close at least one of said port chambers to vary the cross sectional area of said port and effectively alter the velocity of gases into the combustion chamber.

Claim 9. A port assembly of Claim 8. wherein gas pressure in 5 the port or crankcase operates said means to selectively close or open said port.

Claim 10. A port assembly of Claim 8. wherein said means to selectively close at least one of said port chambers is a rotary type valve.

0 Claim 11. A port assembly of Claim 8. wherein said means to selectively close at least one of said port chambers is a guillotine type valve.

Claim 12. A port assembly of Claim 8. wherein said means to selectively close at least one of said port chambers is a butterfly type valve.

Claim 13. A port assembly o. laim 8. wherein said means to selectively close at leasi le of said port chambers is a ball type valve.

Claim 14. A port assembly of Claim 8. wherein said means to selectively close at least one of said port chambers is a flap type valve.

Claim 15. A port assembly of Claim 1. and 8. wherein the means to move the port wall or valve is signaled by engine revs, voltage generated by the engine or engine load.

Claim 16. An internal combustion engine port assembly comprising a body providing a port chamber to communicate with a combustion chamber of said engine, said port chamber having an inlet and an outlet, and means mounted internally of said body and co-operating with said port chamber to provide a port duct through which gas flows, from said inlet to said outlet, and wherein said means at least partly defines a wall surface of said duct along a substantial length thereof and ismoveable to vary the cross sectional area of said duct at said means, to effectively alter the velocity and angle of entry of gases into the combustion chamber.

Claim 17. A port assembly of Claim 16. wherein the engine is of the two stroke cycle.

Claim 18. A port assembly of Claim 17. wherein said port duct is moveable to alter the height of the port outlet opening.

Claim 19. A port assembly of Claim 16. wherein a substantial part of said duct is automatically moved by gas pressure inside the duct.