AU659909B2 - Improvements in internal combustion engines - Google Patents

Description

W0010W1 1 28MV/1 AUSTRALIARegulation 3.2(2) Patents Act 1990 659CVnN

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number.

Lodged: PL 0690 4TH SEPTEMBER, 1992 IMPROVEMENTS IN INTERNAL COMBUSTION ENGINES I S a Invention Title: a a. a a *1 a t a The following statement is a full description of this invention, including the best method of performing it known to us IMPROVEMENTS IN INTERNAL COMBUSTION ENGINES The present invention relates to improvements in internal combustion engines and in particular to improvements relating to valving arrangements for engines of the type disclosed in our co-pending Patent Co-Operation Treaty Application No. PCT/AU88/00009.

In our aforesaid Patent Application there is disclosed a novel arrangement for converting the reciprocating motion of a conventionally arranged piston/cylinder combination to a rotary power output. The novel arrangement includes a transfer mechanism comprising a rotary member adapted to drive an output shaft of the engine, the rotary member defining a cam track of predetermined configuration with a cam follower element adapted to move along the cam track to thereby drive the rotary member (and in response thereto the output shaft). The cam follower member is operably associated with one or more reciprocating piston members and the linear movement of the piston member(s) effects movement of the cam follower element and thereby drives the rotary member and the engine output shaft.

The objective of the present invention is to provide a novel and improved valve mechanism for controlling charge/exhaust gases and combustion gases into, out of and through a multi-cylinder engine, preferably of the aforementioned 20 type. The valve mechanism preferably seeks to minimise or avoid wasted work resulting from power strokes of the piston performing against pressure forces generated in the crank case or on the side of the piston away from the Scombustion zone.

The present invention provides an engine having at least two S: 25 cylinder/piston combinations each adapted to receive a combustible charge to effect reciprocating movement of the piston therein, drive means operably coupled to each said piston to provide an output from said engine, and a valve arrangement for controlling flow of gases into and through said engine, said valve arrangement including an inlet valve means for controlling inlet of and air charge or the combustible charge to each said cylinder, transfer valve means for transferring a said air or combustible charge from a first one of said cylinders to a second one of said cylinders and exhaust valve means for exhausting a combusted charge from said cylinders, said valve arrangement being characterised in that said transfer valve means remains open for a period of time during a power stroke of the piston in said first cylinder to thereby transfer the air or combustible charge in said first cylinder to said second cylinder, the piston in said second cylinder being held substantially stationary during at least a major part of said transfer prior to performing a compression stroke in said second cylinder. Preferably the valve arrangement is a rotary valve mechanism coupled to an output shaft forming part of the drive means. Conveniently the drive means includes a transfer mechanism of the type described in co-pending Patent Co-Operation Treaty Application No. PCT/AU88/00009.

In one preferred arrangement a combustible charge comprising a fuel/air mixture is drawn into the respective cylinders through the inlet valve means. In a second preferred embodiment an air charge might be drawn into the respective cylinders through the inlet valve means with fuel being injected into the introduced air at an appropriate time. Fuel injection might advantageously occur during transfer of the air charge from the first cylinder to the second cylinder or it might advantageously occur after exhaust port or exhaust valve closes.

Conveniently, during inlet of the air or combustible charge to any one cylinder, the inlet valve means for that cylinder remains open while the exhaust 20 valve and the transfer valve means remain closed. During transfer from one cylinder to the next cylinder of the air or combustible charge, the transfer valve means and the exhaust valve means may remain open. During exhaust blow down only the exhaust valve means is open.

The arrangement according to this invention has the advantage that a charge of air and/or combustible gas can be delivered to near constant pressure from one cylinder to the next. The advantages that result include controlling transfer of the charge; (ii) a reduction in negative work; (iii) reduced turbulence during scavenging; (iv) mixing reduced during scavenging stroke; reduced vacuum pressure in the air intake manifold; (vi) reduced temperature drop in the air intake manifold; (vii) fuel may easily be injected during transfer; (viii) induces ram charging of air during the induction stroke; and (ix) induces ram charging of air during the transfer stroke.

Further preferred features and aspects of the present invention will become apparent from the following description given in relation to the accompanying drawings, in which Figures la to ld are schematic position diagrams of a three cylinder engine showing the relative positions of the pittons and the inlet, exhaust and transfer valves; Figure 2a is a diagrammatic cross-sectional view showing a three cylinder engine with the valve arrangement in an air intake position; Figure 2b is a diagrammatic view similar to Figure 2a with the valve arrangement in an air transfer position; Figure 2c is a diagrammatic view similar to Figure 2a with the valve arrangement in a position exhausting one cylinder and transferring air from a second cylinder into the cylinder being exhausted; Figure 3 is a partial longitudinal cross-sectional view through two cylinders showing diagrammatically the valve arrangements according to the present invention in a position transferring air from one cylinder to another Figure 3a is a view similar to figure 3 showing only one cylnder with the valve arrangement in an exhaust configuration; and Figure 3b is a view simlar to Figure 3 showing only one cylinder with the valve arrangement in an intake configuration.

Referring first to Figures 2 and 3, an engine incorporating a valve arrangement includes a plurality of cylinders C1, C2 and C3 (three in the embodiment illustrated), each with a piston P1, P2 and P3. A connecting rod S couples each piston to an output transfer mechanism as shown in co-pending S" Patent Co-Operation Treaty Application NO. PCT/AU88/00009 which in turn drives an output shaft. The output shaft is located co-axially between the cylinders C1, C2 and C3 through the zone 11 in a valve arrangement 12 (Figure A spark ignition means is located in each cylinder in the space 13 provided S therefor.

The rotary valve arrangement 12 is conveniently coupled to the output shaft and therefore rotates in correct timed relation therewith for proper operation of the engine. The valve arrangement may incljde an inlet valve 14 having a peripheral cylindrical skirt with a port 18 therein which opens a corresponding port 11, 12 or 13 in each cylinder wall upon rotation with the output shaft for a period of time during the induction stroke of each piston/cylinder. The valve arrangement 12 also includes a transfer valve which may comprise a member with a cut out or passage 16 in its periphery adapted to connect adjacent transfer ports T1 and T2, T2 and T3 or T3 and T1 of the respective cylinders upon rotating the valve 15 with the output shaft. The valve arrangement 12 further includes an exhaust valve 17 conveniently also having a peripheral skirt with a port opening adapted upon rotation to sequentially open exhaust ports El, E2 and E3 leading from each of the cylinders. Conveniently the exhaust valve 17 includes an inwardly and forwardly directed projection or deflection from the leading edge of the port which assists in exhausting combusted products from the cylinders. It will of course be appreciated that the valve arrangement 12 as described may include multiple ports in the inlet and exhaust valves and multiple cut out portions in the transfer valve member depending on timing requirements for any particular engine design. As will be apparent from Figures 2 and 3, the transfer ports T1, T2 and T3 may lead to passages which distribute the charge delivered around the respective cylinder. Conveniently the valve arrangement includes a rotary exhaust manifold which allows exhaust gas to exit through one common outlet.

The aforesaid deflector on the inside leading edge of the exhaust valve port S 25 creates a low pressure zone to accelerate blow down of the exhaust gases. The G.o deflector also tunes out any bad effects of high pressure waves.

t It is also seen as an advantage to be able to adapt the uniflow system to this engine by providing conventional poppet valves located in the clearance space whilst employing the rotary valve mechanism for both the air intake and air transfer gates. This also provides the means whereby the expansion (working) stroke is lengthened. Also, the effective compression stroke is shortened by delaying the closure of the exhaust valves. It would be evident that an increase in exhaust gas pressure by regulation would increase the mass of combustible gas and consequently increase the compression ratio which would provide a means for regulating the compression ratio. Another method is to use the rotary valves to gate the air intake and air transfer but using conventional poppet valves in the clearance space so as to gain the advantage of having a uniflow air flow system.

Referring now to Figures la to Id, there is shown schematically the sequential operation of the engine and valve arrangements shown in Figures 2 and 3.

Referring to Figure 1 a, cylinder C1 is shown where the piston P1 is moving towards top dead centre with the inlet port II open resulting in an induction of either an air charge or a combustible charge as desired.

In Figure Ib, a previously induced and compressed combustible charge is ignited ard the piston P1 moves from top dead centre towards bottom dead centre in a power stroke. Preferably as the piston P1 begins to move in this power stroke the transfer port T2 opens to enable the charge induced by the previous stroke to be transferred to the second cylinder C3. During this transfer the piston P3 in the second cylinder remains substantially stationary at an adjacent bottom dead centre position.

Figure Ic shows where the piston P1 has reached bottom dead centre by which time the transfer port T2 has closed and the transfer port T1 has opened to enable introduction of a charge to the cylinder C1 from the third cylinder C2.

Figure ld (similar to Figure la) shows the piston P1 compressing the charge introduced from the third cylinder C2 while simultaneously inducing a fresh charge into the lower end of cylinder C1 to be subsequently transferred to cylinder C3. Similar sequential operations are carried out in the other cylinders as will be apparent from Figures la to id.

Claims (9)

1. An engine having at least two cylinder/piston combinations each adapted to receive a combustible charge to effect reciprocating movement of the piston therein, drive means operably coupled to each said piston to provide an output from said engine, and a valve arrangement for controlling flow of gases into and through said engine, said valve arrangement including an inlet valve means for controlling inlet of an air charge or the combustible charge to each said cylinder, transfer valve means for transferring a said air or combustible charge from a first one of said cylinders to a second one of said cylinders, and exhaust valve means for exhausting a combusted charge from said cylinders, said valve arrangement being characterised in that said transfer valve means remains open for a period of time during a power stroke of the piston in said first cylinder to thereby transfer the air or combustible charge in said first cylinder to said second cylinder, the piston in said second cylinder being held substantially stationary during at least a major part of said transfer prior to performing a compression stroke in said second cylinder.

2. The engine as defined in claim 1 wherein during the transfer of the said air or combustible charge from said first cylinder to said second cylinder the piston in the second cylinder remains substantially stationary at an adjacent bottom dead centre position. S

3. The engine as defined in either claim 1 or 2 wherein the said valve arrangement is a rotary valve mechanism coupled to an output shaft forming part of the said drive means.

4. The engine as defined in claim 3 wherein the said rotary valve mechanism rotates in correct timed relation with the said output shaft to achieve proper operation of the engine.

The engine as defined in any one of claims 1 or 4 wherein the said air or combustible charge is delivered at near constant pressure from said first cylinder via said transfer valve means to said second cylinder.

6. The engine as defined in any one of claims 3 to 5 wherein the transfer valve comprises a member with a cut out or passage in its periphery adapted to connect adja. nt transfer ports of the respective cylinders upon rotating the valve with the output shaft.

7. The engine as defined in any one of claims 3 to 6 wherein the rotary valve mechanism further includes an exhaust valve having a peripheral skirt with a port opening adapted so as to sequentially open exhaust ports leading from each of the cylinders upon rotation of the rotary valve mechanism.

8. The engine as defined in claim 7 wherein the exhaust valve includes an inwardly and forwardly directed projection or deflection from a leading edge of the port so as to assist in exhausting combusted products from the cylinders.

9. The engine as defined in claim 8 wherein the valve arrangement further includes a rotary exhaust manifold which allows exhaust gas to exit through a common outlet. DATED THIS 14TH DAY OF MARCH, '995 GEELONG ENGINE CO. PTY. LTD. p. 4 S. WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD o.o HAWTHORN VICTORIA 3122 AUSTRALIA DOC08 AU003219593.WPC 4 1 ABSTRACT An engine having at least two cylinder/piston combinations each adapted to receive a combustible charge to effect reciprocating movement of the piston therein, drive means operably coupled to each said piston to provide an output from said engine, and a valve arrangement for controlling flow of gases into and through said engine, said valve arrangement including an inlet valve means for controlling inlet of and air charge or the combustible charge to each said a cylinder, transfer valve means for transferring a said air or combustible charge from a first one of said cylinders to a second one of said cylinders and exhaust valve means for exhausting a combusted charge from said cylinders, said valve arrangement being characterised in that said transfer valve means remains open for a period of time during a power stroke of the piston in said first cylinder to thereby transfer the air or combustible charge in said first cylinder to said second cylinder, the piston in said second cylinder being held substantially stationary during at least a major part of said transfer prior to performing a compression stroke in said second cylinder.