AU735754B2 - Improvements in rotary machines - Google Patents

Description

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-1- P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT *c 4

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ORIGINAL

Name of Applicant: Actual Inventor: IAN ALISTER MACDONALD IAN ALISTER MACDONALD Address for service in Australia: CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia Invention Title: IMPROVEMENTS IN ROTARY MACHINES Details of Associated Provisional Application: filed 29 JULY 1997 The following statement is a full description of this invention, including the best method of performing it known to us This invention relates to improvements in rotary machines such as compressors and motors and relates particularly to such a machine which can be used as a compressor for compressing air or refrigerant or for any other gas compression or which can be designed to operate as a motor to drive an output shaft. For the purposes of this specification, the invention will be described in relation to its application as a compressor for simplicity.

BACKGROUND OF THE INVENTION Centrifugal compressors and reciprocating compressors are well known.

However, in both centrifugal and reciprocating compressors, substantial losses occur and inefficiencies result from the inability to take full advantage of the inertia of the reciprocating and rotating machine parts.

Accordingly, the efficiencies centrifugal and reciprocating compressors is relatively low and much of the kinetic energy of the rotating machine parts is wasted.

It is therefore an object of the invention to take full advantage of the kinetic energy which exists in rotating and reciprocating machine parts.

It is also desirable to provide an improved compressor using pistons to compress gas, such as air or a refrigerant or the like and wherein the greater part of the energy stored in a moving piston system is used in the total energy system.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention there is provided a compressor including a rotating system having a first plurality of cylinders and cooperating pistons which are mounted on a flywheel driven by a motor and ~adapted to rotate about an axis, the cylinders and pistons being equally spaced about 25 the axis, at least one crank journal offset from the flywheel axis, crank means connecting the journal and said pistons, whereby rotation of the flywheel about its rotational axis causes a corresponding rotation of the piston and crank means system about the crank journal axis thereby giving rise to relative movement of the pistons within the cylinders so that, on achieving a minimum predetermined angular momentum, the reciprocal movement of the pistons within the cooperating DCC:TG:40406484 RS2 30 April 2001 cylinders results in compression of gas within the cylinders, and gas inlet and outlet means to convey gas to and from the cylinders.

Preferably, the crank means is such that the distance between the piston and the crank journal is variable, thereby enabling the rotating system to commence rotation without relative piston and cylinder movement.

Preferably, the cylinders are mounted on a rotating flywheel which rotates DCC:TG:40406484 RS2 30 April 2001 -3about the axis. In one form of the invention, the crank means comprises a connecting rod which directly connects the crank pin to the at least one journal. The connecting rod, in a particular form of the invention, is of two parts interconnected so as to enable the length of the connecting rod to be varied between limits. In another form, pistons are connected to the crank journal by means of a connecting rod or cable and a pivoted lever, one end of which connects to the pistons by way of a connecting rod and the other end of which carries a weight which is urged outwardly under the action of centrifugal force. In another embodiment, the pistons are connected to the crank pin by a flexible cable.

oo 10 In order that the invention is more readily understood, embodiments thereof will now be described with reference to the accompanying drawings: DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional side elevational view of a compressor in accordance with the first embodiment of the invention; 15 Fig. 2 is a diagrammatic front elevational view of the compressor of Fig 1; Fig. 3 is a view similar to that of Fig 1. illustrating a multiple cylinder I configuration; Fig. 4 is a diagrammatic illustration of a further embodiment of the invention; Fig. 5 is a side elevational view of the embodiment of Fig 4; and 20 Fig. 6 is a diagrammatic front elevational view of a third embodiment of the invention.

Referring to Figs. 1 to 3, the compressor of the present invention comprises a flywheel 12 driven by an electric motor 14 through shaft 16. The flywheel 12 carries an array of cylinders 17. As shown in Fig. 2, there may be four cylinders equally spaced around the axis of the shaft 16. However, Fig. 3 shows a double bank of cylinders 17, making a total of eight in all, and there may be any number of cylinders or banks of cylinders 17 mounted to the flywheel 12.

Each cylinder 17 houses a corresponding piston 18. The respective pistons 18 are connected to a crank pin 19 by a connecting rod 21. The connecting rods 21i shown in Fig. 1. are two part connecting rods, the parts being slidable relative to DCC:HHF:#25873.CAP 28 July 1998 -4each other so that the connecting rod can shorten when the piston has insufficient force to compress the gas in the cylinder 17. This condition will occur during start up and before the flywheel has reached its operating speed.

Each cylinder 17 has associated therewith a gas outlet 22 and a gas inlet 23.

Both gas outlet 22 and inlet 23 have valves, such as reed valves, (not shown) to control movement of gas through the outlet 22 and inlet 23.

In operation of the compressor, the electric motor 14 rotates the flywheel 12 in the direction shown by the arrow in Fig. 2. Until the flywheel 12 comes up to operating revolutions, the sliding type connecting rods 21 will allow the pistons to 10 have minimal movement within the cylinders 17. This reduces the power required during start up. Once the flywheel 12 has reached operating speeds, the pistons 18 radially outwardly within their respective cylinders 17 under the action of centrifugal force, thus compressing gas within the cylinder. The compressed gas passes out of the respective cylinders 17 through the gas outlets 22 and through the centre of the drive shaft 16 to the main outlet 26. Thus, as the gas passes towards the flywheel centre and out through the shaft 16, it gives up its centrifugal energy Soo.

but retains the gas pressure.

The pistons then move back towards the rotation axis of the flywheel 12, also giving up their previously gained kinetic energy to the flywheel. The pistons are not 20 necessarily drawn back by the connecting rods 21 but, because the crank pin 19 is offset from the flywheel axis, the speed of movement of the piston is reduced and the energy is released to the flywheel through the sideways forces applied by the pistons 18 to the sides of the cylinders 17. When the pistons reach the bottom of the cylinder, they again take the energy back from the rotational flywheel.

After the operating speed has been reached, the input energy required from the motor 14 to keep the compressor operating is not the energy expended in the compression stroke but is only that energy required to overcome friction and to induce gas into the cylinders during intake stroke. The gas drawn into the cylinder 17 is compressed by the piston 18 moving towards the rim of the rotating flywheel 12 and as the piston moves outwardly using centrifugal force from the flywheel, the DCC:HHF:#25873.CAP 28 July 1998 gas is compressed and exits the cylinder through the gas outlet 22.

It will be appreciated that the mass and size of the piston as well as its centrifugal speed will determine the pressure able to be generated in the gas in the cylinder. The acceleration and deceleration applied to the piston during each revolution results in forces between the piston and the flywheel which ensure that the energy developed in the pistons is passed to the flywheel during the deceleration of the pistons.

Put another way, if the piston 18 is taken in isolation with its connecting rod 21 attached to the crank 19, and the piston 18 and connecting rod 21 are rotating 10 around the crank 19, and the piston 18 is not drawn back by the connecting rod 21, but the piston revolution speed is forced to decrease and increase withl each revolution of the piston 18, the energy taken from the piston 18 when it is deaccelerated is stored in the flywheel 12 and is then used to accelerate the piston again during the next part of the revolution cycle. Very little of this energy is lost.

15 It will be understood that the offset of the crank pin 19 from the rotational centre of the flywheel 12 causes the pistons 18 attached to the crank pin 19 by the connecting rods 21, to move in a different orbit to that of the cylinders 17. This varies the centrifugal speed of the pistons 18 with each revolution of the flywheel 12. The pistons 18 are forced to increase their centrifugal speed as they orbit 20 towards the outer heads of the cylinders 18 while the pistons slide within the respective cylinders 17. The rotary motion of the flywheel and the cylinders 17 fixed thereto imparts energy to the pistons at this time.

When the pistons 18 reach the end of their orbit, before they reach the top or cylinder head end of the cylinder 17 the gas compressed by the piston in the cylinder passes through the gas outlet 22. The pistons 18, which are still orbiting in a circular path, but one which is offset to that of the flywheel 12, commenced to move away from the cylinder heads and take in a fresh charge of gas for the subsequent compression stroke. As the pistons 18 slide in the cylinders 17 away from their cylinder heads, they are moving towards the centre of the flywheel and are forced to give up all of the centrifugal speed that they gained during the compression DCC:HHF:#25873.CAP 28 July 1998 -6stroke. This action takes place each revolution of the flywheel 12, cylinders 17, pistons 18 and connecting rods 21.

When the pistons 18 and the cylinder heads are orbiting towards each other, the full mass of the pistons and the gas within the cylinders is supported by the cylinder head and, therefore, by the flywheel 12 with very little force carried by the crank pin 19. The energy in the piston is therefore transferred to the flywheel and the gas under compression which is exhausted through the centre driving shaft of the flywheel 12 where the gas gives up its centrifugal force.

As the piston 18 is orbiting away from its cylinder head, a fresh charge of gas 10 is entering the cylinder 17, the piston 18 is sliding in the cylinder 17 towards the o centre of the flywheel 12, and it must therefore give up some of its speed and energy to the cylinder wall and onto the flywheel 12.

On starting the compressor of this embodiment, the electric motor 14 causes the flywheel 12 to rotate and the pistons 18 gradually move out towards the cylinder 15 heads as they gain speed. Once the flywheel is up to normal operating speed, only friction needs to be overcome by the driving motor 14 to keep the compressor running and compressing gas. The motor 14 should not have to drive against any ••go friction caused when the pistons are moving outwardly. That friction loss is .:.removed from the outward force of the pistons 18 and comes from the centrifugal .i 20 speed of the flywheel 12, as does the compression of the gas.

The effort needed to take the gas into the cylinder should not effect the input from the drive motor 14. This work is felt as an extra pressure difference on the connecting rod side of the piston and as the piston is not pulled back but rotates on its orbit, this pressure difference should not slow the piston speed. The pressure differential on the outside of the cylinder should also not slow down the rotation because the cylinders are on the rotating flywheel.

Referring to Fig. 4, the modified form of the invention is illustrated in which the connecting rod is replaced by a cable 27. With this arrangement, the piston 18 is free to move within the cylinder 17 until the cable is tensioned. Because of the offset crank pin, the cable 27 causes the piston to move towards the bottom of the DCC:HHF:#25873 CAP 28 July 1998 -7cylinder 17 thereby transferring kinetic energy to the flywheel. As the piston moves towards the bottom of the cylinder, gas is drawn into the top of the cylinder for compression on the subsequent portion of the rotation of the flywheel 12.

Referring to Fig. 6, the modified form of the invention is illustrated in which the pistons 18 are connected to the crank pin 19 by means of the crank levers 31.

Crank levers 31 are pivoted to the sides of the cylinders 17 by the fulcrum 32, and the outer ends of the crank levers 31 carry weights 33. By means of the weights 33 and the crank levers 31, leverage is used to provide an increased compressive force to gas within the cylinders 17.

With the embodiment illustrated, there is shown a method of using mechanical energy by use of centrifugal force and an arrangement of offset crank pins and moving weights which are attached to pistons by crank levers 31. As the see flywheel 12 rotates, the weights and pistons move across the flywheel and take :energy therefrom when moving towards the outer rim of the flywheel. Kinetic 15 energy is returned to the flywheel when the weights are moved towards the centre thereof. Thus, useful work can be done by the pistons in compressing gas within the cylinders.

DCC:HHF:#25873.CAP 28 July 1998

Claims (6)

1. A compressor including a rotating system having a first plurality of cylinders and cooperating pistons which are mounted on a flywheel driven by a motor and adapted to rotate about an axis, the cylinders and pistons being equally spaced about the axis, at least one crank journal offset from the flywheel axis, crank means connecting the journal and said pistons, whereby rotation of the flywheel about its rotational axis causes a corresponding rotation of the piston and crank means system about the crank journal axis thereby giving rise to relative movement of the pistons within the cylinders so that, on achieving a minimum predetermined angular momentum, the reciprocal movement of the pistons within the cooperating cylinders results in compression of gas within the cylinders, and gas inlet and outlet means to convey gas to and from the cylinders.

2. A compressor according to claim 1 wherein the crank means is such that the .distance between the piston and crank journal is variable.

3. A compressor according to claim 1 or claim 2 wherein said crank means comprises a connecting rod formed of two parts which are slidably connected.

4. A compressor according to claim 1 or claim 2 wherein said crank means e comprises a flexible cable, wire or other flexible member. S5. A compressor according to any one of the preceding claims wherein the oo o cylinders are connected to a shaft and a motor is adapted to drive the shaft to rotate the cylinders about the axis.

6. A compressor according to claim 5 wherein said shaft is hollow and forms part of the gas outlet means. r7. A compressor according to any one of the preceding claims wherein said DCC:TG:40406484 RS2 30 April 2001 crank means includes a lever arm pivotably mounted relative to the cylinder and connected to the piston, the arm carrying weight means on its outer end.

8. A compressor substantially as hereinbefore described with reference to the accompanying drawings. DATED: 30 April 2001 Freehills Carter Smith Beadle Patent Attorneys for the Applicant: IAN ALISTER MacDONALD o* o **oO° DCC:TG:40406484 RS2 30 April 2001