WO2004007911A1

WO2004007911A1 - Multi-cylinder engine linear to rotary motion converter

Info

Publication number: WO2004007911A1
Application number: PCT/AU2003/000896
Authority: WO
Inventors: Alan Patrick Casey; Malcolm J. Beare
Original assignee: Alan Patrick Casey; Beare Malcolm J
Priority date: 2002-07-10
Filing date: 2003-07-10
Publication date: 2004-01-22
Also published as: AU2002950119A0

Abstract

A multi-working chambered linear to rotary motion converter wherein each chamber is defined by opposed first and second pistons and the multiple chambers are formed into at least one row or bank. Each of the first pistons being coupled via a common first shaft and each of the second pistons being coupled via a common second shaft. There being a drive coupling between the first and second shafts whereby a predetermined relationship between the motion of each piston pair is provided.

Description

MULTI-CYLINDER ENGINE LINEAR TO ROTARY MOTION CONVERTER

Technical Field

The present invention relates to linear to rotary motion converters as may be adapted to function such as an engine or a pump. The following disclosure will be provided with reference to internal combustion engines and more particularly to engines of the type disclosed in WO 96/12096, FR 2633010, US 1590940 and US 2435361, by way of example, and the contents of which are included herein by reference together with the contents of Australian Provisional Patent Application No. PM 8910 of 18 April, 1994. It will be appreciated, however, that the present invention in its broadest aspect is not limited to the environment of internal combustion engines.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Throughout this specification unless the context requires otherwise, the word

"comprise", and variations such as "comprises" or "comprising" , will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Background

Those aforementioned prior art disclosures show engines having a single cylinder or a pair of different diameter cylinders which contain respective pistons that move toward and away from each other during cycles of operation of the engine. The pair of pistons define opposite ends of a common combustion chamber. In order to obtain the full range of benefits of engines of the type contemplated by the prior art described above it is desirable to provide multi-combustion-chambered engines of, such as, in-line, flat, or V- type configurations. To that end the present invention proposes a method and means for achieving a multi-combustion-chambered engine of an arrangement comprising a multiplicity of units, wherein each unit comprises a combustion chamber having a pair of opposed pistons defining opposite ends of that combustion chamber.

hi the environment of engines of the type with which the present invention is concerned, it is essential to have the multiple paired-piston cylinders operate with a defined relationship between the motion of each associated pair of pistons, as will be understood from the prior art referenced above. Of course, in a multi-cylinder arrangement there needs to be a predetermined sequence of firings between each combustion chamber in order to obtain a smooth output from the output shaft or shafts of such an engine.

As used herein "first" and "second" piston have the same meaning as in WO

96/12096.

Disclosure of Invention

The present invention provides a multi-working chambered linear to rotary motion converter wherein each chamber is defined by an opposed piston pair comprising a first piston and a second piston, said converter functioning by means of a predetermined relationship between the motion of the first and second pistons of each opposed pair wherein the relationship is controlled by a drive coupling from a rotary shaft controlled by the first pistons to a common drive for the second pistons, the common drive being in the form of a shaft having an axis of rotation parallel to the axis of rotation of the rotary shaft.

In accordance with an embodiment of the present invention a multi-combustion- chambered engine of the kind contemplated achieves a predetermined relationship between the motion of the second pistons relative to the first pistons of each pairing by means of a drive coupling from a power output shaft, in the form of a crankshaft, of the first pistons to a common drive for the second pistons, the common drive being in the form of a shaft having an axis of rotation parallel to the axis of rotation of the power output shaft of the first pistons.

In a preferred form of the present invention the common drive shaft for the second pistons is below a plane defining the top of a bank of cylinders of the multi-working chambered linear to rotary motion converter.

i another preferred form the common drive shaft is external to the converter, as such.

In a still further preferred form, the common drive shaft is fitted with bevel gears which are mated with complementary bevel gears associated with each respective second piston so as to provide means for effecting a 90° change of rotational direction from that of the common drive shaft, h one example of the last mentioned preferred form, the bevel gears are square cut.

In a further particularly preferred arrangement the bevel gears are helically cut so as to substantially reduce the noise emanating from the meshing of those gears.

In yet another embodiment the common drive is coupled to respective first pistons by any one of a belt or a chain or a shaft drive or a gear train or suitable combination of such drives.

In a further embodiment where the common drive shaft is external to the engine, that common drive shaft is a hollow drive shaft.

With a single cylinder engine of the kind shown in the drawings of WO 96/12096 it is a relatively simple exercise to reset the timing relationship between the first and second pistons. That can be achieved by removing the timing belt/drive chain connecting the first and second pistons and resetting the angular relationship between the respective cranks for the first and second pistons before refitting the timing belt/drive chain with the'pistons in that changed timing relationship. In another embodiment, a variable drive^' pulley is provided on the crankshaft of the second pistons to advance the timing relationship during start-up and reduce the compression ratio by early opening of the exhaust port to dump heat to a catalytic converter. Other advantages may arise in having facility to vary the timing during engine operation. The second piston will still, of course, cycle at half the rate of the first piston but the phase relationship between their movements will be displaced from where they were before the change.

In a multi-combustion-chambered engine of an embodiment of the present invention it will also be a relatively easy exercise to change the timing relationship between the first and second pistons of each bank or array of pistons. In a bevel gear driven arrangement of one preferred form of the present invention a belt or drive chain interconnects the output of the first pistons to the common drive for the second pistons. The pulley ratio between the drive shaft for the first pistons and the common drive for the second pistons is appropriately 2:1. Again, removing the timing belt/drive chain between the grouped first and second pistons enables the phasing between the motion of the first and second piston groups to be altered to thereby change the inlet and exhaust valve timing facilitated by each of the second pistons relative to their respective first pistons. A simple refitting of the timing belt/drive chain with the first and second pistons in that altered phase relationship results in a reset of the inlet and exhaust valve timing for each combustion chamber.

It is also a relatively simple exercise to change the relative opening and closing positions by fitment of replacement engine cylinder heads or sleeves containing the second pistons with cylinders or sleeves having different distances between the bottom edges of

,the inlet and exhaust ports formed in the cylinder wall or cylinder sleeve for the second pistons as compared with the original cylinders or sleeves. ^*

Preferably, embodiments with bevel gears on the common drive shaft for the second pistons have those bevel gears axially movable along splines on that drive shaft so as to compensate for expansion and contraction as relevant components of the engine expand and contract with changes in temperature. Additionally, it is also preferred that where an exhaust rotary valve is employed that it is fixed on its axis of rotation and not free to move along that axis during engine operation.

Brief Description of Drawings

The present invention will now be described by way of example with reference to the accompanying drawings, in which :

Figure 1 is identical to Figure 5 of Australian Patent Application No. PM 8910;

Figure 2 is identical to Figure 6 of WO 96/12096;

Figure 3 is an isometric view of a preferred embodiment of a multi-combustion- chambered engine in accordance with the present invention as viewed from the front at the upper left-hand side;

Figure 4 is a plan view of the engine of Figure 3;

Figure 5 is an isometric upper left-hand rear view of the engine of Figure 3; and

Figure 6 is a rear elevation view of the engine of Figure 3.

Best Modes

Figures 1 and 2 show embodiments of prior art single combustion chamber dual- piston engines of the type generally relevant to the present invention which are described in the specifications of Australian Provisional Application No. PM 8910 and WO 96/12096, respectively. The reference numerals in Figure 2 correspond with those same numerals on Figure 6 of WO 96/12096. The embodiment of the present invention of Figures 3 - 6 shows an engine 30 having a V-4 layout. Each combustion chamber having paired pistons as shown generally by Figure 2 but with the scotch yoke mechanism and its slide 51 atop piston 7 being rotated through 90° so as to be driven by respective bevel gear drives 31 mounted on the same side as inlet ports or apertures 14. In this embodiment the bevel gear drives 31 for the respective second piston scotch yoke mechanisms also drives the rotary valve 17 which seals off exhaust aperture 15 from exhaust port 16 in a suitably timed relationship with movement of the respective first pistons. Closure of port 16 by rotary valve 17 prevents the back flow of exhaust gases into combustion chamber 12 during each induction stroke as typified by the views shown in Figures 1 and 2.

The rear timing belt 32 fitted between the common bevel gear drive shafts 33 for each bank of cylinders 34 functions to dampen the reverse power feed from each firing combustion chamber to spread that load evenly over the bevel gear drives for the combustion chambers which are not then firing. Without that rear timing belt it is possible that the reverse power feed could cause some back slap in a "V" configuration multi- combustion chambered engine where tolerances are not fine enough between engine components. The rear timing belt 32 is shown for the purpose of dampening that back slap and to balance the forces on the respective shafts 33.

Finally, it is to be understood that the inventive concept in any of its aspects can be incorporated in many different constructions so that the generality of the preceding description is not to be superseded by the particularity of the attached drawings. Various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.

Claims

WE CLAIM :

1. A multi- working chambered linear to rotary motion converter wherein each chamber is defined by an opposed piston pair comprising a first piston and a second piston, said converter functioning by means of a predetermined relationship between the motion of the first and second pistons of each opposed pair wherein the relationship is controlled by a drive coupling from a rotary shaft controlled by the first pistons to a common drive for the second pistons, the common drive being in the form of a shaft having an axis of rotation parallel to the axis of rotation of the rotary shaft.

2. A converter as claimed in claim 1 wherein the common drive shaft is below a plane defining the top of a bank of cylinders of the multi-working chambered converter.

3. A converter as claimed in claim 1 or 2 wherein the common drive shaft is external to a body of the converter housing the opposed piston pairs.

4. A converter as claimed in any one of the preceding claims wherein the common drive shaft is fitted with first bevel gears mated with complementary second bevel gears associated with each respective second piston.

5. A converter as claimed in claim 4 wherein the bevel gears are square cut gears.

6. A converter as claimed in claim 4 wherein the bevel gears are helically cut gears.

7. A converter as claimed in any one of claims 1-3 wherein the drive coupling includes a belt or chain drive.

8. A converter as claimed in any one of claims 1-3 wherein the drive coupling includes a shaft drive or a gear train.

9. A converter as claimed in any one of the preceding claims wherem the common drive shaft is a hollow shaft.

10. A converter as claimed in any one of the preceding claims when adapted to function as an internal combustion engine.

11. A converter as claimed in any one of the preceding claims wherein the working chambers are arranged in-line.

12. A converter as claimed in any one of claims 1 to 10 wherein the working chambers are arranged in a "V" formation.