GB2301150A - External combustion engine with rotary displacer - Google Patents

Abstract

An external combustion engine, where a contained mass of gas has its mean pressure cyclically increased and decreased by passing it through heat exchangers 22 and 23. The pressure difference drives an output assembly, such as crankshaft 11. Item 40 represents a heat source, item 24 an automotive type radiator and fan assembly. The gas is driven around the engine by a non-reciprocating displacer 25, and is routed by a rotary valve 30 with skirt 31 and port 32. Displacer 25 and rotary valve 30 are driven by gearing from crankshaft 11. 17 is a second gas chamber; 36 a gas top-up pump; and 39 is a safety valve. By adjustment of the valve timing, and reversal of the displacer, the engine may be driven through the crankshaft by an external power source, to act as a heat pump.

Description

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER Field of this Invention THIS PRESENT INVENTION RELATES TO AN EXTERNAL COMBUSTION ENGINE WHICH USES ANY GAS THROUGH A CONTINUOUS FLOW DISPLACER, AND FLOW DIRECTOR VALVE.

Background to the Invention As its name implies the external combustion engine burns the energy fuel outside the engine instead of within the working cylinder. Thomas Savery's steam pump of 1698 had no piston and can probably be considered as the first effective external combustion engine.

Later in 1816 Robert Stirling invented a free-piston or hotair engine which depended for its power on the expansion and displacement of air, or other gases, inside a cylinder heated by external combustion.

The working gases such as hydrogen, helium or nitrogen are sealed within the system and are alternatively heated and cooled by being passed through external heat exchangers.

In 1936 Philips of Holland worked on several external combustion engine which increased the mean pressure to about 20 bar: and included a regenerator to recover some of the heat being lost between the heating and cooling cycle.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER External combustion engines producing 110-BHP per litre and operating at 4400 revolutions per minute have been developed since then which make use of helium at high pressures. It was realised that the use of helium was unsatisfactory because of the many ways it diffused and therefore had to be replenished to maintain operation.

An external combustion engine which uses any gas to form a transfer medium between the "hot" and the "cold" chambers with little heat loss and which uses a non-reciprocating flow device, such as a fan or a turbine, to create movement of the gas through the external heat source in the shortest possible time is the subject of this invention.

The direction and distribution of the gas is by means such as a ported rotary valve which is placed cyclically opposite outlet apertures to transfer heated gas and gas under various pressure levels throughout the operation of the engine.

Accordingly, the embodiment of this invention comprises a linear to rotary conversion section such as a crankcase assembly in which is a crankshaft, piston rod and piston.

The piston reciprocates within a cylinder and acts upon a volume of gas which is itself heated externally to the cylinder and will increase in pressure until it exceeds that below the piston.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER The piston will then be forced downwards into the cylinder until the gas pressure each side of the piston equalises.

During the downward movement of the piston the rotary valve would have rotated to a position - where the hot gases exit to a heat exchanger and the pressure above the piston decreases and during the completion of the downward stroke of the piston, the pressure beneath it will increase and force the piston upwards again.

In the chamber above the piston is sited a non-reciprocating displacer, such as a turbine impeller which is gear driven and revolves at a much greater speed than the crankshaft.

The turbine moves the gas through a heater matrix and through a heat exchanger as the cycle of operation proceeds.

The heater matrix receives its heat from an external heat source which could be any known fuel combustion system. The heat exchanger may be liquid-filled cooled by any appropriate sized fan operating against an automotive type radiator. If it were possible economically to reduce the temperature in the exchanger to zero degrees centigrade or below, it is obvious the overall efficiency of the engine would be enhanced.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER The rotary valve and the turbine impeller are driven by gearing and are not directly connected to the crankshaft although the rotary valve rotates at the same speed as the crankshaft because timing is critical to the performance of the engine.

The characteristics of this external combustion engine provide low toxic exhaust emissions and make little noise in operation since the only noise source would be the combustible fuel burner. The efficiency would be less than that expected of an internal combustion engine in terms of power per litre but the external combustion engine will burn any combustible fuel such as rice husks, wood, sugar cane waste, coal, sawdust and such like waste products, making it eminently suitable for third world countries. This type of engine is also used as a heat pump, when driven by an external motor, producing useful heat, or, several engines run in series, producing cryogenic temperatures. The engine described herein may also be used as a heat pump, with suitable valve timing, or reversal of turbine blade direction.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER A specific example of this invention, together with its advantageous effects will be explained in greater detail with reference to the embodiments shown diagrammatically and by way of example only in the accompanying drawings in which: Figure 1 is a sectional drawing of the complete external combustion engine.

Figure 2 shows the upper gear chamber of the external combustion engine and the turbine impeller.

Also shown is the rotary valve which separately gear driven Referring to Figure 1 the external combustion engine 10 is illustrated in section with the crank shafting 11 connected in the traditional manner to a connecting rod 12 and cross head 13. The piston 14 reciprocates within the cylinder 15 and reacts to gas in the chambers 16 and 17.

The crank shaft 11 is contained within a crank case 18 below which would be the traditional oil sump 19. In this embodiment the piston 14 extends from the crosshead 13 on a piston rod 20 which is guided in a sleeved bushing 21.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER Immediately above the cylinder 15 is the turbine inlet chamber 16 to which is attached the hot gas matrix 22 and the heat transfer exchange 23. Heat is given up to the exchanger 23 with the aid of an automotive type radiator and fan 24 which is not fully detailed in Figure 1 because this unit follows already amply documented art.

Within the chamber 16 is provided a turbine impeller 25 which is gear driven by shafting 26 and gear train 27,28,29.

This turbine impeller 25 displaces the gases at various stages during the cycle or operation, which will be later described.

Within the chamber 16 and embracing circumferentially the turbine impeller 25 is the rotary valve 30.

This said rotary valve is cylindrical in outline shape with a larger diameter "skirt" 31 also cylindrical, at the lower end. A single aperture 32 is provided through the skirt 31 which represents the outlet port for the transfer of gases from within the chamber 16 to one or other of the heat exchange modes. The rotary valve 30 is caused to rotate at the same speed as the crank shaft 11 by gear train 33,34 and which is driven by shafting 35.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER The rotary valve 30 is supported by a plurality of ball or roller bearings as is also the impeller shafting 26.

Inevitably there will be losses of the hot gases during the continuous operation of the external combustion engine and replenishment is effected by extraneously mounted pump assembly 36. The mean effective pressure within the Chamber 16 will be controlled by the valve 37 through ports 38 in the chamber 17.

A safety valve ~~ is provided which is signal operated and which will equa e the pressures in the chambers 16 and 17 and cease the operation of crank shaft 11. The safety valve 39 is linked to the fuel burner assembly 40 which is only schematically indicated in Figure 1.

Referring now to Figure 2 there is shown a view of the gear chamber 41 to illustrate more clearly the rotary valve 30 and the gear driven turbine impeller 25. The gear chamber format provides adequate support fcr the ball or roller bearings 42 which permit the rotary valve 30 to be driven freely by the gears 34,33.

It can be seen from Figure 2 that a plurality of ball or roller bearing 43 is also provided inside the rotary valve 30 which give support to the shafting 26 of the turbine impeller 25 and the rotary valve 30.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER Shown by broken lines is an exit port 44 which is provided through the chamber 16 through which the hot gases pass to the regenerator (not shown). Port 44 is more clearly visible in Figure 2 than in Figure 1 - its purpose in the cycle of operation will be more clearly defined in subsequent text.

Figure 2, view 2a, shows the rotary valve 30 separately illustrated and view 2b indicates the significantly important positions of the exit port 32 during the cycle of operations. Position 1 relates to the piston 14 being at top dead centre and the port 32 communicating with the heater matrix 22 under the influence of the turbine impeller 25.

Position 2 relates to the piston having turned through 90 degree's and the rotary valve aligning with port 44 to transfer hot gases to the heat regenerator.

The next 90 degrees rotation of the crankshaft 11 causes the piston 14 to compress air in the chamber 17 below the piston and this pressure will be then greater than pressure of the gas in chamber 16 and the piston will rise. The port 32 in the rotary valve 30 will communicate with an inlet port to the cooling matrix 23.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER This will be position 3. As the piston rises to half stroke the rotary valve 30 will place the exit port 32 to communicate with a port opposite to 44 in chamber 16 which returns cooled gas to the turbine impeller 25 by way of the regenerator - this is position 4. A more detailed explanation of the engine cycle will now be given by way of example.

With the piston 14 at top dead centre the port 32 in the rotary valve 30 is receiving gas under the influence of the turbine impeller 25 and directing it into the heater matrix 22 where it will increase in pressure. Under pressure the gas passes from chamber 46 back to the turbine impeller 25.

The piston 14 descends in the cylinder 15 because the pressure of the gas in chamber 16 is greater than the air pressure in chamber 17 but it will be about equal when the piston reaches half downward stroke.

At the position of half stroke the rotary valve 30 has caused the hot gas to exit through port 44 (Figure 2) to the heat regenerator which communicates with port 45 in chamber 16.

EXTERNAL COMBUSTION ENGINE WITH A NON-RECIPROCATING DISPLACER A further 90 degree rotation of the crankshaft 11 will place the piston 14 to compress air in the chamber 17 and this pressure will increase to be greater than the gas pressure in chamber 16 which will cause the piston 14 to reverse upwards. The gas in chamber 16 will exit through a port in chamber 49 towards the heat exchanger 23 and back through chamber 47 to the turbine impeller 25. This reduction in the temperature of the gas having passed through the heat exchanger 23 will reduce its pressure to a level less than that in the chamber 17 and thus create turning torque on the crank shaft 11. At half upward stroke the pressures in chambers 16 and 17 will equalise and the port 32 in the

rotary valve 30 is directing gas through a port (not shown) which is diametrically opposite to port 44 (Figure 2)

which links with a channel in rear of they and thus impart heat to the gas which will enter chamber 16 through port 45.

The piston will have risen to top dead centre and the rotary valve 30 to uncover the port to chamber 50 and cycle begins again.

Claims (5)

1 An engine which can provide a mechanical power output, by means of the cyclic provision of alternate heating and cooling of a fixed mass of contained gas under high mean pressure, the flow of which within the engine being provided by a non reciprocating displacer, and direction of flow being controlled by a valve system, the gas being heated by passing it through an externally powered heat exchanger, and cooled by passing it through another externally cooled heat exchanger.

2 An engine, similar to that in claim 1, which, with the valve and displacer suitably adjusted, will perform as a heat pump when external power is supplied to the output shalt extracting heat from the cold heat exchanger, and rejecting heat from the hot heat exchanger.

3 An engine, as claimed in claim 1 or claim 2, employing a continuous flow gas displacer, such as a rotary fan or turbine.

4 An engine, as claimed in claim 1 or claim 2, employing a sealed chamber below the power device to relieve the power device and output mechanism of the effects of high gas pressure.

5) AN ENGINE, ONE EXAMPLE OF WHICH IS ILLUSTRATED IN FIGURE 1, THE INDIVIDUAL DETAILS THEREIN ARE FOR ILLUSTRATION ONLY.

5 An engine, as claimed in claim 1 or claim 2, employing a simple ported rotary valve to control the direction of gas flow.

6 An engine, one example of which is illustrated in figure 1, the individual details therein are for example only.

Amendments to the claims have been filed as follows CLAIMS 1) AN ENGINE WHICH CAN PROVIDE A MECHANICAL POWER OUTPUT BY MEANS OF THE CYCLIC PROVISION OF ALTERNATE HEATING AND COOLING OF A FIXED MASS OF CONTAINED GAS UNDER HIGH PRESSURE, THE FLOW OF WHICH WITHIN THE ENGINE BEING PROVIDED BY A NON-RECIPROCATING DISPLACER, AND ITS DIRECTION OF FLOW BEING CONTROLLED BY A PORTED ROTARY VALVE SYSTEM, THE GAS BEING HEATED BY PASSING IT THROUGH AN EXTERNALLY POWERED HEAT EXCHANGER, AND COOLED BY PASSING IT THROUGH AN EXTERNALLY COOLED HEAT EXCHANGER, THE TIMING OF WHICH IS CONTROLLED BY THE PHASE RELATIONSHIP OF THE OUTPUT SECTION AND THE ROTARY VALVE.

2) AN ENGINE, SIMILAR TO THAT CLAIMED IN CLAIM 1, HAVING THE PHASE RELATIONSHIPOF THE ROTARY VALVE TO THE OUTPUT SHAFT SUITABLY ADJUSTED, WILL PERFORM AS A HEAT PUMP WHEN EXTERNAL MECHANICAL POWER IS SUPPLIED TO THE OUTPUT SHAFT, HEAT BEING EXTRACTED BY ONE HEAT EXCHANGER AND REJECTED AT A HIGHER TEMPERATURE FROM THE OTHER HEAT EXCHANGER.

3) AN ENGINE, AS CLAIMED IN CLAIM 1 OR CLAIM 2, EMPLOYING A CONTINUOUS-FLOW DISPLACER IN THE FORM OF A FAN OR TURBINE.

4) AN ENGINE, AS CLAIMED IN CLAIM 1 OR CLAIM 2, EMPLOYING A SEALED CHAMBER BELOW THE POWER OUTPUT DEVICE ARRANGED TO RELIEVE THE POWER OUTPUT SYSTEM OF THE EFFECTS OF HIGH GAS PRESSURE.