WO1997032111A1

WO1997032111A1 - Fluid machines

Info

Publication number: WO1997032111A1
Application number: PCT/AU1997/000129
Authority: WO
Inventors: Peter Robert Raffaele
Original assignee: Peter Robert Raffaele
Priority date: 1996-03-01
Filing date: 1997-03-03
Publication date: 1997-09-04
Also published as: AUPN840796A0

Abstract

The invention provides a fluid machine (10) having a main axis (11) and a plurality of pistons (42) arranged in a circle. A hub (14) rotates relative to a block (16) about the axis (11) and has cams (44) for converting the linear motion of the pistons (42) into rotary motion of the hub (14) or vice versa. The cams (44) are located radially outwards of the pistons (42) and respective chambers (40). The cams (44) are mounted on the hub (14) and engage the block (16) so that they rotate relative to the hub (14) as the hub (14) rotates.

Description

This invention relates to reciprocating piston fluid machines, such as internal combustion engines or pumps in which fluid is pumped by the reciprocating action of a piston in a cylinder.

The vast majority of reciprocating piston devices convert rotary motion of an input shaft to reciprocating linear motion of the piston by use of offset cranks. The use of offset cranks has various disadvantages and it has been proposed or replace such arrangements with cams which rotate about their own axis and about the axis of the motor. The use of cams reduces, amongst other things, vibration. One such device is described in PCT International Patent Application No. PCT/AU91/00224. In the device of PCT/AU91/00224 the pistons are arranged radially, with the cams located radially inwards from the pistons and the combustion chambers radially outwards of the pistons. It is proposed that such an engine or pump have 12 pistons arranged circumferential ly about the axis of the motor. This leads to the need to have, for instance, 12 sets of spark plugs (in the case of a petrol engine), 12 sets of intake and exhaust manifolds and valves (if used), etc. Furthermore, the volume radially inwards of the rotating cams tends to be unused and wasted, leading to an unduly large engine. Thus, whilst the basic concept may be relatively simple, the practical form may not be so. Furthermore, the arrangement of the cams relative to the piston followers results in impacts as each cam contacts the followers.

In an attempt to overcome some of the disadvantages of the prior art, the invention, in one broad form, provides a fluid device comprising: a block having a main axis and at least one bore therein remote from the axis; a piston mounted in a respective bore for reciprocal movement along a piston axis, each bore and its respective piston defining a chamber; a converting mechanism engaging the or each piston and for converting the linear motion of the or each piston into a rotary motion; wherein for the or each piston, the piston axis: a s para e o e ma n ax s; or b) intersects the main axis with the chamber between the point of intersection and the respective piston.

In another broad form, the invention provides a machine comprising: a plurality of camshafts, each being rotatable about its own axis and orbital about a central axis, each camshaft including at least one cam: at least one piston reciprocable in a respective cylinder housing and arranged to be sequentially contacted by the cams as they orbit the central axis, the cams of at least two camshafts being in contact with the at least one piston at all times.

The camshafts may be driven about their own axis by a gear system at constant speed with constant orbital speed or may be driven by a conjugate cam system, so allowing variable cam shaft rotational speed with constant orbital speed.

Preferably, there are multiple pistons arranged radially about the axis;

Preferably, each piston has its own chamber. Alternatively, one chamber may be shared by two or more pistons;

Preferably, the piston or pistons are mounted on a block and the block has an inlet for exhaust and a passageway extending coaxial with the axis.

The invention shall be better understood from the following non-limiting description of embodiments of the invention, in which:

Fig. 1 is a schematic axial cross-sectional view of a first embodiment of the invention.

Fig. 2 is a schematic axial cross-sectional view of a second embodiment of the invention. . the invention.

Fig. 4 is a schematic axial cross-sectional view of a fourth embodiment of the invention.

Fig. 5 is a schematic axial cross-sectional view of a fifth embodiment of the invention.

Fig. 6 is a schematic axial cross-sectional view of a sixth embodiment of the invention.

Fig. 7 is a schematic sectional end view taken along line BB of figure 6.

Fig. 8 is a schematic axial cross-sectional view of a seventh embodiment of the invention.

Fig. 9 is a schematic axial cross-sectional view of an eighth embodiment of the invention.

Fig. 10 is a schematic axial cross-sectional view of a ninth embodiment of the invention.

Fig. 11 is a schematic sectional end view of a tenth embodiment of the invention.

Fig. 12 is a schematic sectional end view of the fig. 11 embodiment at a different position.

Fig. 13 is a schematic sectional end view of a twelfth embodiment of the invention.

Referring to Fig. 1 , there is shown a fluid machine 10 which comprises a stationary circular block 12 and a rotating circular hub 14. The block 12 in turn comprises left and right block halves 16, 18. The left and right block halves are clamped together by way of axially extending rod 20, spacer 22 and end bolts 24. The rod 20 passes through an axial passageway 26 in each block halves relative to each other.

The hub 1 is mounted on the block 12 by way of bearings 30 and 32 for rotation about axis 11.

Each block half 16, 18 has a series of cylinder bores 40 located about the circumference and directed radially inwardly toward the axis 11. Located in each cylinder bore 40 is a piston 42, which may reciprocate linearly within the respective cylinder bore 40.

Located radially outwards of the pistons 42 are cams 44. The cams 44 may act directly on pistons 44 or followers may be provided. The cams 44 are mounted on camshafts 46 which in turn are mounted for rotation on the hub 14 by way of bearings 48.

The machine 10 is provided with multiple cams 44 and cam shafts 46, located in a ring about axis 11. Each camshaft 46 also has two drive gears 50, one on either side of the cams. The drive gears 50 engage with ring gears 52 formed on the block 12. Thus as hub 14 rotates relative to the block 12, the gears 50, 52 engage and cause the camshafts 46 to rotate about their axes 47 relative to the hub 14 as well as rotating about block axis 11. This causes the cams to pass over each piston 42 and so cause it to reciprocate in cylinder bore 40.

Output from the device or input to it is via ring gear 60 formed on the outer periphery of the hub 14. This gear 60 may engage with a gear shaft or the output of a suitable motor, depending on use.

The construction of the device allows for relatively easy assembly and modularity. Once the pistons 42 have been located in the respective bores 40, the hub 14 and its associated cams and camshafts can be mounted on one block half. Once this is done the other block half may be engaged with the hub and the first block half. single rod 20 passing through all blocks 12. A single geared output/input shaft may then engage the ring gears 60 of each hub 14.

Fig. 2 shows a variation of the Fig. 1 device in which there is a single unitary 5 block 112 and in which the output is to one side.

In this embodiment the block 112 is generally tubular with a closed bore 116 extending axially from one end.

The hub 114 is tubular and extends over the block 112 from the other end. The block 114 is mounted for rotation on the block 124 by bearings 130 and 10 132. The operation of the pistons, cams and camshafts is as per the Fig. 1 device.

The hub 114 is provided with a inner ring gear 118. An idler gear/auxiliary take off shaft 120 is mounted on the block and engages the gear 118. This shaft 120 may be connected to a distributor, oil pump or any other accessary 15 requiring power.

Mounted within the bore 116 on bearings 122 and 124, is a hollow shaft 12 which is open at one end and closed at the other.

The shaft 126 acts as either an inlet manifold or exhaust manifold and is connected at its open end to suitable fluid supply or exhaust equipment (not 20 shown).

Each cylinder is provided with one or more inlet/exhaust passageways 128 which communicate with the bore 116. The shaft 126 has a series of openings 134 in its surface so as to allow the passageways 128 to communicate with its interior and hence the inlet or exhaust device.

25 The shaft 126 is provided with a gear 136 which engages with gear 120. Thus, when the hub 114 rotates, the shaft 126 does so as well and selectively opens and closes the passageways 128 in the manner of a conventional disc valve . speed. Other means may be provided to cover the shaft 126 to rotate in an intermittent manner or at a variable velocity during one complete cycle.

Fig. 3 shows a third embodiment of the invention, which is configures similarly to the Figs. 1 and 2 embodiments. For simplicity, the device only has three pistons mounted in the hub 212. However, more than three pistons may be used.

In this embodiment, the cylinder bores 240 are not discrete but extend toward the centre of the hub 212 until they meet. The crown of each piston 242 is tapered so that all three may move toward the centre without interfering with each other. The three pistons 242 and the interconnecting bores 240 thus define a closed chamber 244. Preferably, the bores are non-circular so as to allow the pistons to close up against each other without excessive crevice space. It will be appreciated that by suitable design, the pistons need not touch but merely extend to the end of each bore to define, at its smallest, a triangular shaped chamber. If this occurs, a circular bore may be used.

With this arrangement, it will be appreciated that only a single spark plug is required for three pistons. Similarly, the inlet or exhaust porting arrangements may be simplified. For instance, inlet ports 248 may be provided in one or both end walls and controlled by a disc valve driven by the rotating hub 214. The exhaust ports may then be located in the outer extremities of the cylinder bores 240.

This provides an improved fluid flow within the cylinders whilst retaining a simple porting arrangement without poppet valves.

Fig. 3 also shows the arrangement of the cams 244 relative to each other and the pistons 242. The arrangement of Fig. 3 device is used in Figs. 1 and 2 devices. around the hub 214. The two sets overlap and so they are offset axially relative to each other. As the hub 214 rotates, each cam contacts the follower 250 of each piston and movement of the piston is communicated to the cam or vice versa.

Fig. 4 shows a variation of the Fig. 3 device. Each piston 342 is provided not with a follower but with an undulating outer surface 350, with two peaks 352 and three troughs 354. As the cams rotate, they will alternatively engage the piston at its peaks 352 or troughs 354, thus providing for a motion other than simple harmonic. By suitable cam design, the period at "top dead centre" may be different from that at "bottom dead centre".

Fig. 5 shows a further variation of the invention, in which inlet and exhaust flow is axial through the device. This embodiment is similar to the Fig. 2 device, except there is a single bank of pistons and cylinders. The block 412 is hollow and a hollow shaft 426 is mounted within the axial bore 416 of the block 412. This shaft is geared for rotation to the hub 414 as in the Fig. 2 device. However, the shaft 426 is provided with a central barrier 430. One side 426a of the shaft thus forms the inlet of the device and the other side, 426b, the outlet or exhaust. The shaft 426 is provided with inlet openings 432 which communicate with inlet passageways in the block 412 and outlet openings 434 which communicate with outlet passageways in the block 412. The inlet and outlet passageways in turn communicate with the cylinders 440. As in the Fig. 2 device, rotation of the hub 414 causes rotation of the shaft 426 and selectively opens and closes the inlet and outlet passageways.

Figs. 6 and 7 show a further embodiment of the invention, 600.

The device 600 comprises a stationary block 610 having a plurality of pistons 612 arranged in a plane perpendicular to an axis 614 for movement parallel to the axis 614. The pistons 612 are arranged circumferentially about the axis , , opposed so as to share a common chamber.

A hub 616 is mounted on the block 610 for rotation about the axis 614. Mounted in the block 610 are camshafts 618 with associated cams 620 and cam gears 622. The cam shafts 618 are arranged to extend radially from axis 614 and are mounted on the block by way of bearings 624, 626, 628.

The cam gears 622 engage on an annular ring gear 630. Thus as hub 616 rotates and causes the cam shafts to rotate about axis 61 , they in turn rotate about their own axes and cause pistons 612 to reciprocate.

As seen in the figures, each piston is acted on by multiple cams per camshaft. The radially innermost cams have a lower circumferential velocity than the outer cams in the configuration shown, where camshafts are parallel to the plane of the pistons. With constant size cams this will result in sliding of the cams on the pistons due to the different circumferential velocity across the pistons but constant velocity of the cams themselves. To reduce this, the camshafts may be angled to diverge from the plane of the pistons, with the cams increasing in size with distance from the axis 614. This will ensure that the contact velocity and circumferential velocity of the cams are better matched, so reducing/eliminating any sliding.

Figure 8 shows a variation of the fig. 2 device in which adjacent pistons 820 are linked by appropriate rocker arm 822. The rocker arm is pivotably mounted in the hub at point 823 and to the pistons. This alleviates problems associated with there being no fixed link between the pistons 820 and the cams 824. During use, the pressure of any gas in the cylinders 826 will tend to maintain the pistons 820 in contact with the cams 824. However, at start up there is no such pressure. The use of rocker arms ensures that the pistons cannot "fall" to the bottom of their cylinders and so all of them may be driven by the cams at start up. As an alternative, each piston may be biased against the cams.

Fig. 9 shows a further embodiment of the invention. . , 914 each of which is arranged in a set of bores extending inwardly from opposed cone shaped surfaces 916, 918 respectively. These are coaxial about axis 913. Outside of the block 910 is a hub 920 which is mounted on the block 5 910 for rotation about axis 913. The hub 920 has two sets of camshafts 922 and associated cams 924 mounted for rotation relative to the hub. Each set of camshafts is parallel to the respective cone surface 916, 918 and has a bevel gear 926 which engages a ring gear 928 on the block 910. Thus rotation of the hub about axis 913 causes rotation of the camshafts 922 and reciprocation of 0 the pistons 912, 914. The pistons thus reciprocate along lines at 45° to the main axis. It will be appreciated that the pistons may be arranged to reciprocate along a line at any angle between 0° and 90° to the main axis, subject to the chamber being radially inwards of the piston when the angle is not 0°, i.e. not parallel to the axis.

5 Fig. 10 shows a variation of the fig. 9 device in which the pistons 912, 914 all share a common compression chamber 950 as opposed to separate chambers.

Figs. 11 and 12 show a variation of the cam arrangement which may be used with any embodiment of the invention.

0 All of the devices described only have a single cam acting on the piston at one time. Referring to the fig. 3 device, each piston is provided with a follower 250 which is sequentially contacted by a cam. Transfer from one cam to the next occurs at the position shown in fig. 3.

At the point of transition the follower 250 and piston 242 is travelling outward 5 at almost maximum speed, because the contact point to the cam centre is almost perpendicular to the followers direction of travel. The next cam is moving so that when it contacts the follower, it requires an equally large velocity, but downwards. Thus the changeover results in impact, very high accelerations and accordingly high loads. , each piston at all times, as shown in figs. 11 and 12.

In the fig. 11 embodiment there are provided pistons 1010 within block 1011. A series of cams 1012 are mounted in a hub 1013 and geared for rotation as previously described.

Each piston 1010 has a rear face 1014 which has a radius of curvature equal to the radius of the block 1011. The cams 1012 are sized and located so as to rotate about the block with minimal clearance and are each provided with five lobes N to R, although each cam may have more or less than five lobes.

In figure 11 the pistons are at top dead centre since a radius line from the block centre 1020 to each cam centre 1022 pass through the contact point of cam with piston 1024. As can be seen, two adjacent cams 1012a and 1012b contact the piston 1010a.

The cams 1012 rotate clockwise about their own axes, as indicated by arrow A whilst the hub 1013 rotates anticlockwise, as indicated by arrow B. Thus as the hub 1013 rotates the cam centres rotate anticlockwise relative to the pistons as shown in fig. 11 so cam 1012a moves to the pistons anticlockwise edge and lobe O connects the piston whilst lobe N has paved off the side of the piston. Cam 1012b remains in contact with the piston and whilst lobe N remains in contact with the piston, lobe O is brought into contact with it. Similarly, cam 1012c rotates so that its N lobe contacts the piston.

When the cams are oriented as in fig. 12 this represents bottom dead centre.

A further part rotation of the hub will cause only cams 1012b and 1012c to contact the piston, in a similar position to that of fig. 11 , with cam 1012a no longer in contact with it.

Because the cams contact the piston with motion in the same direction, there need not be any abrupt changes of piston direction and in particular, no rapid accelerations. by changing the cam shape between the lobes which cause the piston to move to top dead centre.

Fig. 13 shows a further variation of the invention.

Whilst the other embodiments of the invention utilise a gear arrangement between the camshafts and the block to cause camshaft rotation, the fig. 12 device utilises a conjugate cam arrangement rather than a gear arrangement.

A conjugate cam comprises two cams, one the mirror image of the other which always engage their follower's engagement surfaces and enable perfect control over the cam.

In the fig. 13 embodiment the block 1210 is provided with a conjugate cam 1212 instead of the ring gear. The conjugate cam 1212 comprises a first cam surface 1212a and a second cam surface 1212b, staggered axially relative to the first cam surface 1212a. The cam surface 1212b is a mirror image of the surface 1212a.

Each camshaft is provided with a follower which comprises two sets of three rollers each. The three rollers of each set are arranged at the corners of an equilateral triangle and mounted on a yoke, which in turn is attached to the camshaft. One set of rollers contacts the cam surface 1212a whilst the other set contacts the cam surface 1212b. As the hub rotates around the block, the action of the cam surfaces on the block 1212 is to cause rotation of the camshafts.

The advantage of utilising a conjugate cam drive is that better control over piston timing may be achieved compared to a gear drive. The conjugate cam system enables one to control the rotational speed of the camshafts. More particularly, it is possible to have variable camshaft rotational speed for a constant hub rotational speed. Thus, for instance, by reducing or stopping camshaft rotation at bottom dead centre, the dwell of the piston at that position camshafts.

It will be apparent to those skilled in the art that many modifications and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention.

Claims

. A fluid device comprising: a block having a main axis and at least one bore therein remote from the axis; a piston mounted in a respective bore for reciprocal movement along a piston axis, each bore and its respective piston defining a chamber; a converting mechanism engaging the or each piston and for converting the linear motion of the or each piston into a rotary motion; wherein for the or each piston, the piston axis : a) is parallel to the main axis; or b) intersects the main axis with the chamber between the point of intersection and the respective piston.

2. The device of claim 1 wherein the converting mechanism comprises a hub mounted for rotation about the main axis relative to the block.

3. The device of claim 2 wherein the converting mechanism comprises at least one cam mechanism, mounted on the hub for rotation about a cam axis relative to the hub, for engaging the piston or pistons.

4. The device of claim 3 wherein the at least one cam mechanism engages the block whereby rotation of the hub relative to the block causes rotation of the cam mechanism relative to the hub.

5. The device of claims 3 or 4 wherein the or each cam axis is not parallel to the main axis.

6. The device of any one of claims 3 to 5 wherein the or each cam axis is not at 90° to the or each piston axis.

7. The device of any one of claims 1 to 6 wherein the or each piston axis is parallel to the main axis.

8. The device of any one of claims 1 to 7 comprising at least one set of multiple bores, each set arranged circumferentially about a point.

9. The device of claim 8 comprising at least two sets of bores arranged side by side in parallel planes. . e ev ce o c a m compr s ng at eas wo se s o ores arrange a out a common centre point but at different radii from the common centre point.

11. The device of any one of claims 1 to 10 wherein the block has an inlet or outlet chamber or both and the each respective chamber selectively communicates with the inlet or outlet chamber or both via a valve mechanism.

12. The device of claim 11 wherein the hollow interior is cylindrical and the valve mechanism comprises a valve member rotating about the main axis relative to the block.

13. The device of claim 12 wherein the inlet chamber or outlet chamber or both comprise a cylindrical chamber coaxial with the main axis and the respective valve member comprises a cylindrical rotating within the cylindrical chamber.

14. The device of claim 13 comprising inlet and outlet chambers arranged end- on-end.

15. The device of claim 14 comprising a cylindrical valve member closed intermediate its ends.

16. The device of any one of claims 1 to 15 comprising at least two bores and respective pistons, and wherein the at least two bores are in fluid communication with each other.

17. The device of claim 3 or any one of claims 4 to 16 when dependent on claim 3 wherein the converting means comprises a plurality of cams, the cams sequentially contacting the on each piston as the hub rotates about the main axis, at least two cams being in contact with the at least one piston at all times.

18. The device of claim 4 or any one of claims 5 to 17 when dependent on claim 4 wherein the cam mechanism engages the block via a conjugate cam system.

19. A fluid device, substantially as herein described with reference to the drawings.