WO2015104524A1

WO2015104524A1 - A heat engine

Info

Publication number: WO2015104524A1
Application number: PCT/GB2014/050037
Authority: WO
Inventors: Jack Pearce
Original assignee: Jack Pearce
Priority date: 2014-01-07
Filing date: 2014-01-07
Publication date: 2015-07-16

Abstract

A heat engine (10) is disclosed having the benefits of reduced noise and vibration of moving parts, improved life expectancy and relatively high conversion efficiency, in particular by limiting use of reciprocating parts. The heat engine (10) comprises a series of rotating elements (120, 160) that define regions for containing a working fluid. Some of the regions are heated, and some of the regions are cooled. Flow of the working fluid through passages (170) between the regions, and the expansion and/or contraction of the fluid as it is heated and/or cooled, drives rotational movement of the rotating elements (120, 160), thereby extracting mechanical work.

Description

A HEAT ENGINE

The present invention relates generally to heat engines and a method of converting thermal energy into mechanical work and finds particular, although not exclusive, utility in power generation systems.

Combined Heat and Power (CHP) stations burn a fuel at a location at which heat is required (for instance in the domestic setting where central heating is desirable) and additionally produce electricity from this heat. Such 'home' power stations use more of the energy given off by the fuel and take away the losses that arise from transporting electricity from remote locations, which are often well away from domestic regions.

There are many known methods for producing electricity from a heat source. One commonly used example, is the steam driven turbine due to its high efficiency. However due to its complexity, it is expensive to replicate in small scale CHP stations. Another example is the Peltier cooler (or thermoelectric plate). The Peltier cooler can produce electricity directly without any moving parts, which makes them silent. However, due to their very low conversion efficiency (approximately 5%), their cost per watt of electricity is prohibitive. A still further example is the Stirling heat engine, due to its simple design and therefore low cost and relatively high efficiency. However, Stirling engines embody a reciprocating piston design that produces vibrations and therefore noise. Even well designed engines with soundproofing, still need to be located away from quiet areas in the home. In particular, woodstoves are often used as the heat source for such CHP stations. However, woodstoves are generally located in living areas where they can be enjoyed and tended. Producing electricity from this heat source would need to be very quiet to be considered acceptable.

Heat engines convert heat into mechanical work, and are not limited to use with any specific form of heat production. The mechanical work may then be used to generate electricity. For instance, heat engines may be used to generate power from heat produced through exothermic reactions (such as combustion), from geothermal heat sources, by absorption of light or energetic particles (such as in solar heating systems and/or nuclear reactions), and as a side effect of another desired process (such as by friction, dissipation and/or resistive heating).

Various designs of heat engines are known in which heat is converted into mechanical work by cooling a working substance from a higher thermal energy to a lower thermal energy. These heat engines take advantage of various thermal cycles such as phase change cycles, gas only cycles, liquid only cycles, electron cycles, magnetic cycles, refrigeration cycles, evaporative cycles and/or mesoscopic cycles, in which the working substance may be fluid (for instance liquid, gas, charged particles and/or plasma), or solid (for instance magnetic materials).

One example of such an engine is the Ericsson engine, in which: cold gas within a first part of a cylinder is compressed by a first side of a piston; the cold compressed gas is moved into a tank; the cold compressed gas is moved into a regenerator where it is preheated; the preheated compressed gas is moved into a second part of the cylinder adjacent a second side of the piston, where it is heated; the gas expands and does work on the piston as it moves upward (the expansion stroke); the hot gas is pushed back through the regenerator by the piston (the exhaust stroke), where it loses heat; and the gas is further cooled and returned to the first part of the cylinder to repeat the sequence.

Another example of a known heat engine is the alpha Stirling engine, in which: hot gas within a heated cylinder holds a first piston in a retracted position, and expands along a passage to a cooled cylinder, where it does work on moving a second piston from an extended position to a retracted position; the first piston is driven by a fly-wheel connected between the first and second pistons into an extended position to move the hot gas into the cooled cylinder, where it cools; the second piston is driven by the fly-wheel to compresses the cold gas in the cooled cylinder; the cold gas expands along the passage into the heated cylinder, where it is heated; and the gas is heated thereby continuing to expand and does work on moving the first piston back to its retracted position.

As is common in heat engines utilising a working fluid, pistons are used to extract mechanical work and to compress the working fluid. Reciprocating motion of such pistons, including the large change in momentum experienced by the pistons, is undesirable, as this may lead to unwanted noise and vibrational damage. In particular, known heat engines are often not suited to the domestic environment due to the noise produced.

Another known type of engine is the rotary engine, such as the rotary Striling Engine, Quasiturbine/Qurbine, and Wankel Engine. However, each of these arrangements include reciprocating components that have a tendency to lead to as much unwanted noise and vibration as a piston, and/or components coupled in such a way that the engines experience high internal frictional losses and become inefficient to operate and have a short life expectancy.

It is therefore desirable to provide a heat engine that is less noisy than prior art arrangements, is less susceptible to wear through continued use, and has a relatively high conversion efficiency.

According to a first aspect of the present invention, there is provided a heat engine for converting thermal energy into mechanical work, comprising: a substantially fluid-tight containment vessel having a containment vessel axis; a plurality of vanes arranged to partition the containment vessel into respective working regions for holding a working fluid, the plurality of vanes configured to rotate independently of one another about the containment vessel axis, such that a leading face of each vane bounds a leading working region and a following face of each vane bounds a following working region; at least one divider arranged to divide each working region into a first part and a second part, wherein the containment vessel is configured to allow heat to enter the first parts such that working fluid therein expands and to allow heat to be removed from the second parts such that working fluid therein contracts; a plurality of passages, each passage associated with a respective vane such that the passage is arranged to provide fluid communication between a first part of a leading working region, and a second part of a following working region, wherein the plurality of vanes are arranged to rotate about the containment vessel axis in response to expansion of working fluid within the first parts, contraction of working fluid within the second parts, and flow of working fluid between the first parts and the second parts; and a rotor configured to constrain rotation of each of the plurality of vanes relative to each other vane within a predetermined angular range and to rotate about a rotor axis in response to rotation of the plurality of vanes about the containment vessel axis, thereby producing torque for generating power; wherein each working region has a volume that is variable between a predetermined maximum volume and a predetermined minimum volume, dependent upon a rotational position of the rotor.

Expansion and contraction of the various parts of the various working regions drives rotation of the vanes about the container vessel axis. Rotation of the vanes about the container vessel axis drives rotation of the rotor about the rotor axis.

When a second part of a following working region has a minimum volume, a first part of a leading working region may expand to a maximum volume and a passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region, thereby causing the second part of the following working region to expand, in response to heating fluid within the first part of the leading working region. When the first part of the leading working region has a maximum volume, the first part of the leading working region may contract and the passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region, thereby causing the second part of the following working region to expand, such that the combined volume of the first part of the leading working region and the second part of the following working region expands to a maximum volume, in response to heating fluid within the first part of the leading working region. When the combined volume of the first part of the leading working region and the second part of the following working region has a maximum volume, the first part of the leading working region may contract and the passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region, thereby causing the second part of the following working region to expand to a maximum volume. When the second part of the following working region has a maximum volume, the first part of the leading working region may contract to a minimum volume and the passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region and the second part of the following working region may contract, in response to cooling fluid within the second part of the following working region. When the first part of the leading working region has a minimum volume, the first part of the leading working region may expand and the passage associated with the vane may convey fluid from the second part of the following working region to the first part of the leading working region, thereby causing the second part of the following working region to contract, such that the combined volume of the first part of the leading working region and the second part of the following working region contracts to minimum volume, in response to cooling fluid within the second part of the following working region. When the combined volume of the first part of the leading working region and the second part of the following working region has a minimum volume, the first part of the leading working region may expand and the passage associated with the vane may convey fluid from the second part of the following working region to the first part of the leading working region, thereby causing the second part of the following working region to contract to a minimum volume.

In some embodiments, when the combined volume of the first part of the leading working region and the second part of the following working region has a maximum volume, the first part of the leading working region may contract and the passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region, thereby causing the second part of the following working region to expand to a maximum volume, in response to cooling fluid within the second part of the following working region, and/or when the combined volume of the first part of the leading working region and the second part of the following working region has a minimum volume, the first part of the leading working region may expand and the passage associated with the vane may convey fluid from the second part of the following working region to the first part of the leading working region, thereby causing the second part of the following working region to contract to a minimum volume, in response to heating fluid within the first part of the leading working region.

In some embodiments, when the combined volume of the first part of the leading working region and the second part of the following working region has a maximum volume, the first part of the leading working region may contract and the passage associated with the vane may convey fluid from the first part of the leading working region to the second part of the following working region, thereby causing the second part of the following working region to expand to a maximum volume, in response to momentum and/or inertia of components of the heat engine, and/or when the combined volume of the first part of the leading working region and the second part of the following working region has a minimum volume, the first part of the leading working region may expand and the passage associated with the vane may convey fluid from the second part of the following working region to the first part of the leading working region, thereby causing the second part of the following working region to contract to a minimum volume, in response to momentum and/or inertia of components of the heat engine.

Flow of fluid between respective parts of working regions may be in response to heating and/or cooling of said parts, and/or momentum and/or inertia of components of the heat engine.

In one embodiment in which there are four working regions, each leading working region may be offset from its respective following working region by a phase angle of 90 degrees. Similarly, in an embodiment in which there are three working regions, each leading working region may be offset from its respective following working region by a phase angle of 120 degrees. In general, each leading working region may be offset from its respective following working region by a phase angle equal to 360 degrees divided by the number of working regions. The heat engine may be able to mimic the thermodynamic cycle of the alpha Stirling heat engine.

The containment vessel may be substantially rotationally symmetric about the containment vessel axis. The containment vessel may be substantially of prismatic form. The containment vessel may have substantially the same cross-section along its axial length. However, other forms, shapes and configurations of the containment vessel are envisaged, such as egg-shape, conical, and various spheroidal arrangements. The containment vessel may be substantially cylindrical. The containment vessel may comprise a containment vessel wall that curves uniformly about the containment vessel axis. The containment vessel may comprise two opposing containment vessel ends, connected to the containment vessel wall thereby defining an internal volume. The containment vessel wall may comprise a plurality of containment vessel bores disposed parallel to the containment vessel axis. The containment vessel may further comprise a plurality of containment vessel bolts configured to pass through the containment vessel bores. The containment vessel ends may comprise containment vessel holes. The containment vessel holes may be arranged to be alignable with the containment vessel bores, such that each containment vessel bolt may be arranged to pass through a containment vessel hole in each containment vessel end and through the containment vessel bore such that the containment vessel ends may be secured to the containment vessel wall by means of containment vessel nuts threadably attached to the containment vessel bolts. One end of the containment vessel may comprise a channel arranged to allow access to the interior of the containment vessel therethrough. The channel may be sealed by a rotary seal. The containment vessel may be pressurised, such that the containment vessel contains a fluid pressurised above atmospheric pressure, for instance pressurised to between approximately 1.5 and 20 atmospheres, in particular between approximately 5 and 15 atmospheres, preferably approximately 10 atmospheres.

The containment vessel may be constructed from a first portion and a second portion. The first portion may contain the first parts therein and the second portion may contain the second parts therein. The divider may comprise divider holes. The divider holes may be arranged to be alignable with the containment vessel bores, such that each containment vessel bolt may be arranged to pass through a divider hole and through the containment vessel bore such that the first and second containment vessel portions may be secured to the divider by means of containment vessel nuts threadably attached to the containment vessel bolts. The containment vessel may include containment vessel gaskets that seal the containment vessel, thereby allowing pressurised fluid to be contained therein.

The heat engine may be made from cast iron, ductile iron, steel, stainless steel carbon graphite and/or other similar materials. The heat engine may be provided with surfaces of low-friction material. In particular, moving parts of the heat engine may be made from and/or coated with low-friction material. The low-friction material may be PTFE, Teflon (RTM), pure carbon, plastic materials impregnated with carbon (for instance, approximately 25% carbon) and/or other materials that may be impregnated with carbon (for instance, approximately 25% carbon). The low-friction materials may be heat resistant. For instance, the low-friction materials may be able to resist temperatures up to 250 degrees centigrade. Moving parts of the heat engine may be made with fine tolerance clearance, such that the moving parts may be spaced from one another. In this way, friction may be significantly reduced.

The containment vessel may be formed substantially from steel. The containment vessel may have an axial length of between approximately 8cm and 5m, in particular between approximately 20cm and 2m, preferably approximately 80cm. The containment vessel may have a dimension perpendicular to the containment vessel axis of between approximately 4cm and 5m, in particular between approximately 10cm and 2m, preferably approximately 80cm.

The containment vessel may be substantially air-tight, gas-tight, water-tight and/or liquid-tight. The containment vessel may prevent substantial loss of working fluid from an interior of the containment vessel.

Reference to a component or group of components forming a 'fluid-tight' region/barrier and/or a 'substantially fluid-tight' region/barrier may include embodiments in which the region is configured such that, over prolonged periods of time fluid may escape from the region; however, in time-scales experienced during operation of the present invention, an insignificant amount of fluid leak is experienced. For instance, in time-scales of between approximately 10ms and 1s, between approximately 0 and 5% of a mass of fluid may leak from a substantially fluid-tight region, in particular between approximately 0 and 3%, and preferably between approximately 0 and 1%. This extends to air-tight, gas-tight, liquid-tight and water-tight embodiments.

The heat engine may comprise two vanes, three vanes, four vanes, five vanes, six vanes, or any other number of vanes. Accordingly, the heat engine may comprise two working regions, three working regions, four working regions, five working regions, six working regions, or any other number of working regions.

The vanes may be substantially flat. The vanes may be configured to extend from one internal axial end of the container vessel to the opposing internal axial end. Alternatively, the vanes may be configured to extend part way from one internal axial end of the container vessel to the opposing internal axial end, for instance, half way. The vanes may be substantially rectangular. The vanes may have a cut-away portion such that each vane is substantially the shape of two co-planar rectangles. In alternative embodiments, the vanes may be flexible. The vanes may flex to engage with an uneven wall of the containment vessel, and/or a containment vessel having a non-circular cross-section.

The vanes may be formed substantially from steel. The vanes may be made from sheet steel of thickness 0.5mm, 1mm, 2mm, 3mm, 4mm, or any other suitable thickness.

The vanes may be disposed within the containment vessel such that they substantially seal against an internal wall of the containment vessel. The working regions may be substantially fluid-tight, air-tight, gas-tight, liquid-tight and/or water-tight.

Each vane may be coupled to a respective vane bearing. Each vane may be coupled to a respective vane bearing via a vane clamp. Each vane may be arranged to rotate about a vane shaft.

The vanes may be arranged to be spaced from the containment vessel and/or the divider. In particular, the vanes may be spaced from the containment vessel and/or the divider by a distance that may prevent frictional forces acting between the vanes and the containment vessel and/or the divider and may provide a substantially fluid-tight barrier to passage of fluid. There may be a fine tolerance clearance between the vanes and the containment vessel and/or divider. Alternatively, the vanes may be touching the containment vessel and/or divider.

The heat engine may comprise only one divider. Alternatively, the heat engine may comprise a separate divider for each working region. The heat engine may comprise any number and combination of dividers.

The divider may be substantially flat. The divider may be configured to extend around the internal periphery of the container vessel. Alternatively, the divider may be configured to extend around the internal periphery of a working region. The divider may be substantially crescent-shaped. The divider may be in the form of a segment of a crescent. The divider may be located within the cut-away portion of the vanes.

The divider may be formed substantially from steel. The divider may be made from sheet steel of thickness 0.5mm, 1mm, 2mm, 3mm, 4mm, or any other suitable thickness.

The divider may be disposed within the containment vessel such that it substantially seals against an internal wall of the containment vessel and/or against the vanes. The first and second parts of each working region may be substantially fluid-tight, air-tight, gas-tight, liquid-tight and/or water-tight. The divider may be located in a plane perpendicular to the containment vessel axis, and may be located approximately half way along the axial length of the containment vessel. The first part of a working region may be substantially the same length parallel to the containment vessel axis as the second part of a working region. The first parts may be substantially the same length parallel to the containment vessel axis as the second parts. The first parts may be substantially the same length parallel to the containment vessel axis as each other. The second parts may be substantially the same length parallel to the containment vessel axis as each other.

The containment vessel may be made from a heat-conducting material. The containment vessel may be locatable with a first axial end adjacent a heat source, such that heat is allowed to enter the first parts such that working fluid therein expands. The containment vessel may be locatable with a second axial end adjacent a heat sink, such that heat is allowed to be removed from the second parts such that working fluid therein contracts. The heat engine may further comprise at least one radiator baffle adjacent the first and/or the second axial end of the containment vessel to increase heat transfer from/to the containment vessel.

The heat engine may have the same number of passages as vanes. The heat engine may have twice the number of passages as vanes. The heat engine may have as many passages as any multiple of the number of vanes.

Each passage may substantially prevent fluid escape from the passage, the leading working region and/or the following working region.

Each passage may comprise a tube that may be integrally formed with the rotor. The passage may be a bore through the rotor. Each passage may be between approximately 0.5cm and 3cm in diameter, in particular between approximately 1cm and 2cm in diameter, preferably approximately 1.5cm in diameter. Each passage may comprise regenerator material therein. In this way, relatively hot fluid moving into the passage may lose heat to the regenerator material, and relatively cool fluid moving into the passage may gain heat from the regenerator material. This may act to increase efficiency of the engine. The regenerator material may be any open-cell foam material, such as a metallic or ceramic foam. Alternatively, the regenerator material may be an open cell honeycomb material. The regenerator material may be metal, ceramic and/or any other suitable material. The regenerator material may be a plurality of elements that may interlock with one another to form a regular or irregular lattice. The regenerator material may be any material that has a large surface area compared to its volume.

The rotor may be substantially cylindrical in form. The rotor may comprise a rotor wall that curves uniformly around the rotor axis. The rotor wall may be between approximately 1cm and 5cm in radial thickness, in particular between approximately 2cm and 4cm, preferably approximately 3cm. The rotor wall may form a cylindrical curved surface. The cylindrical curved surface may be closed at one end by a substantially flat rotor wall. A drive shaft may be fixed to the substantially flat rotor wall. The rotor may be arranged such that the substantially flat rotor wall is disposed in a recess in one of the end walls of the containment vessel. The recess may substantially surround the channel. The rotor may comprise a drive shaft. The drive shaft may extend through a channel in the container vessel that may be arranged to allow access to the interior of the containment vessel therethrough. The channel may be sealed around the rotor drive shaft by a rotary seal. The rotor may be mounted inside the containment vessel on one or more rotor bearings. The rotor bearings may be located at an opposite end of the rotor to the drive shaft. Alternatively, or additionally, the rotor bearings may be located at the same end of the rotor as the drive shaft.

The rotor may be arranged to be spaced from the containment vessel and/or the divider. In particular, the rotor may be spaced from the containment vessel and/or the divider by a distance that may prevent frictional forces acting between the vanes and the containment vessel and/or the divider and may provide a substantially fluid-tight barrier to passage of fluid.

The rotor may comprise coupling means for coupling each of the plurality of vanes to the rotor. The coupling means may comprise slots in the rotor through which the vanes are arranged to pass. In particular, each vane may pass through a respective slot. Each slot may be provided with a vane sealing rod, which may prevent fluid (such as gas, liquid, air or water) from passing into the interior of the rotor from the working regions. The vane sealing rod may comprise two members of substantially semi-circular cross-section. Each member may comprise a flat face arranged to press against a face of one of the plurality of vanes. The members of the vane sealing rod may be arranged such that the flat face of each member faces the other member, such that the vane may be gripped therebetween. Each vane may be gripped by the members with a pressure that permits sliding of the vane therebetween. Each vane may be slidably received in the slots. The vane sealing rod may be disposed within a cylindrical cavity in a wall of the rotor. In this way, the vane sealing rod may rotate within the cavity, such that the angle of the vane with respect to the rotor may be varied.

The rotor axis may be parallel to the container vessel axis. The rotor axis may be spaced from the container vessel axis. The rotor axis may not be coaxial with the container vessel axis. The spacing between the wall of the rotor and the wall of the container vessel may vary with angular position around the container vessel. The rotor may be eccentrically located within the containment vessel. The angular distance between adjacent vanes may vary depending on the degree of angular rotation of the rotor about the rotor axis. The angular distance between adjacent vanes may be a minimum when the spacing between the wall of the rotor and the wall of the container vessel, between the vanes, is at a minimum. The angular distance between adjacent vanes may be a maximum when the spacing between the wall of the rotor and the wall of the container vessel, between the vanes, is at a maximum. The volume of a working region may be a minimum when the spacing between the wall of the rotor and the wall of the container vessel, between the vanes, is at a minimum. The volume of a working region may be a maximum when the spacing between the wall of the rotor and the wall of the container vessel, between the vanes, is at a maximum.

The heat engine may comprise an energy storing and/or momentum storing component, such as a flywheel or other suitable arrangement. The component may be coupled directly and/or indirectly to the drive shaft. The component may be attached to the drive shaft in order to rotate with the drive shaft about a common axis. The component may store rotational energy and/or momentum, which may maintain rotational movement of the rotor throughout the energy cycle of the heat engine. The flywheel may maintain momentum and/or inertia of moving parts of the heat engine, for instance, the rotor and/or the drive shaft.

According to a second aspect of the present invention, there is provided a method of converting thermal energy into mechanical work, comprising: providing a heat engine according to any one of the embodiments of the first aspect of the present invention; heating a first portion of the containment vessel such that heat enters the first parts of the working regions in order for working fluid therein to expand; and cooling a second portion of the containment vessel such that heat is removed from the second parts in order for working fluid therein to contract, wherein the plurality of vanes rotate about the containment vessel axis in response to expansion of working fluid within the first parts, contraction of working fluid within the second parts, and flow of working fluid between the first parts and the second parts, and the rotor rotates about the rotor axis in response to rotation of the plurality of vanes about the containment vessel axis, thereby producing torque for generating power.

According to a third aspect of the present invention, there is provided a heat engine for converting thermal energy into mechanical work, comprising a plurality of units connected in series in a loop such that a unit at one end of the series is connected to a unit at an opposing end of the series, each unit comprising: a first substantially fluid-tight region having a volume that is variable between a minimum volume and a maximum volume, the first region suitable for containing fluid therein, wherein each unit is configured to allow heat to enter its respective first region; a second substantially fluid-tight region having a volume that can be varied continuously between a minimum volume and a maximum volume, the second region suitable for containing fluid therein, wherein each unit is configured to allow heat to be removed from its respective second region; and a passage configured to provide a fluid connection between the first region and a second substantially fluid-tight region of the next unit in the series; the heat engine configured such that: a first fluid-tight region of a first unit is configured to expand to a maximum volume and a passage of the first unit is arranged to convey fluid from the first region of the first unit to a second fluid-tight region of a second unit, thereby causing the second region of the second unit to expand, in response to heating fluid within the first region of the first unit, when the second region of the second unit has a minimum volume; the first region of the first unit is configured to contract and the passage of the first unit is arranged to convey fluid from the first region of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand, such that the combined volume of the first region of the first unit and the second region of the second unit expands to a maximum volume, in response to heating fluid within the first region of the first unit, when the first region of the first unit has a maximum volume; the first region of the first unit is configured to contract and the passage of the first unit is arranged to convey fluid from the first region of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand to a maximum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a maximum volume; the first region of the first unit is configured to contract to a minimum volume and the passage of the first unit is arranged to convey fluid from the first region of the first unit to the second region of the second unit and the second region of the second unit is configured to contract, in response to cooling fluid within the second region of the second unit, when the second region of the second unit has a maximum volume; the first region of the first unit is configured to expand and the passage of the first unit is arranged to convey fluid from the second region of the second unit to the first region of the first unit, thereby causing the second region of the second unit to contract, such that the combined volume of the first region of the first unit and the second region of the second unit contracts to minimum volume, in response to cooling fluid within the second region of the second unit, when the first region of the first unit has a minimum volume; the first region of the first unit is configured to expand and the passage of the first unit is arranged to convey fluid from the second region of the second unit to the first region of the first unit, thereby causing the second region of the second unit to contract to a minimum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a minimum volume; wherein the heat engine further comprises a mechanical coupling, configured to move in response to variation of the volume of each of the first and second substantially fluid-tight regions, thereby producing mechanical movement for generating power.

Each unit may comprise a working region. Each first substantially fluid-tight region may comprise a first part of a working region. Each second substantially fluid-tight region may comprise a second part of a working region.

According to a fourth aspect of the present invention, there is provided a method of converting thermal energy into mechanical work, comprising: providing a heat engine according to any of the embodiments of the third aspect of the present invention; expanding a first fluid-tight region of a first unit to a maximum volume and conveying fluid from the first region of the first unit through a passage of the first unit to a second fluid-tight region of a second unit, thereby causing the second region of the second unit to expand, in response to heating fluid within the first region of the first unit, when the second region of the second unit has a minimum volume; contracting the first region of the first unit and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand, such that the combined volume of the first region of the first unit and the second region of the second unit expands to a maximum volume, in response to heating fluid within the first region of the first unit, when the first region of the first unit has a maximum volume; contracting the first region of the first unit and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand to a maximum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a maximum volume; contracting the first region of the first unit to a minimum volume and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit and the second region of the second unit is configured to contract, in response to cooling fluid within the second region of the second unit, when the second region of the second unit has a maximum volume; expanding the first region of the first unit and conveying fluid from the second region of the second unit through the passage of the first unit to the first region of the first unit, thereby causing the second region of the second unit to contract, such that the combined volume of the first region of the first unit and the second region of the second unit contracts to minimum volume, in response to cooling fluid within the second region of the second unit, when the first region of the first unit has a minimum volume; expanding the first region of the first unit and conveying fluid from the second region of the second unit through the passage of the first unit to the first region of the first unit, thereby causing the second region of the second unit to contract to a minimum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a minimum volume; wherein the mechanical coupling moves in response to variation of the volume of each of the first and second substantially fluid-tight regions, thereby producing mechanical movement for generating power.

It is to be noted that the operation of a heat engine can be reversed in order for operation as a heat pump. Accordingly, the apparatus of the invention may be a heat pump. Similarly, the methods of the invention may be reversed such that a heat differential is created by driving the rotor within the apparatus.

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings, in which:-

Figure 1 is a perspective view of a heat engine according to a first embodiment of the present invention.

Figure 2 is a perspective view of the heat engine of figure 1, with the container vessel removed.

Figure 3 is a perspective view of the heat engine of figure 2, additionally with the divider removed.

Figure 4 is a simplified schematic representation of the heat engine of figure 1.

Figure 5 is a perspective view of the heat engine of figure 3, additionally with the rotor removed.

Figure 6 is a perspective view of the heat engine of figure 5, additionally with the vane arrangements removed.

Figure 7 is a perspective view of one of the vane arrangement of figure 5.

Figure 8 is a vertical section of the heat engine of figure 1, along the line AA of figure 9.

Figure 9 is a horizontal section of the heat engine of figure 1, along the line BB in figure 8.

Figure 10 is a series of horizontal sections similar to figure 9, illustrating the rotational position of the working regions throughout a full cycle.

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term 'comprising', used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression 'a device comprising means A and B' should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment, but may refer to different embodiments. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The use of the term 'at least one' may, in some embodiments, mean only one.

The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the true spirit or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Figure 1 is a perspective view of a heat engine 10 according to a first embodiment of the present invention. The heat engine 10 comprises a containment vessel composed of a substantially circular base plate 20, a lower cylindrical portion 30, an upper cylindrical portion 40 and a substantially circular cylinder head 50. The substantially circular base plate 20 is approximately 20cm in diameter and has a depth thickness of approximately 4cm. The lower cylindrical portion 30 has a diameter approximately equal to the diameter of the substantially circular base plate 20 and an axial length of approximately 10cm. The lower cylindrical portion 30 is coupled to the base plate 20 to form a cup-shaped region therein, with outer peripheral edges of each component being aligned. The upper cylindrical portion 40 is substantially identical to the lower cylindrical portion 30, and is coupled thereto such that their axes are coaxial, with outer peripheral edges of each component being spaced apart by a divider 60. The substantially circular cylinder head 50 is similar in shape to the base plate 20; however, cylinder head 50 further comprises an eccentrically-located substantially cylindrical cup 70 that projects above an upper surface of the cylinder head 50. The cylinder head 50 is coupled to the upper cylindrical portion to enclose a region within the containment vessel, with outer peripheral edges of each component being aligned.

The cup 70 has a diameter of approximately 10cm, and a channel centrally located therein of diameter approximately 5cm. A drive shaft 90 projects through the channel from the interior of the containment vessel. A rotary seal 80 is located within the channel for allowing smooth rotation of the drive shaft 90 within the channel and preventing fluid loss from within the containment vessel. In some embodiments, the rotary seal 80 may include a drive shaft bearing or bearings, to assist with the smooth rotation of the drive shaft 90 within the channel.

The containment vessel further comprises twelve containment vessel bolts 100, each containment vessel bolt 100 passes through a respective bore in each of the base plate 20, lower cylindrical portion 30, upper cylindrical portion 40 and cylinder head 50, and is secured in position with a containment vessel nut 110 at each end, such that the components of the containment vessel are secured together.

Figure 2 is a perspective view of the heat engine 10 of figure 1, with the container vessel partially removed. Within the containment vessel, and directly coupled to the drive shaft 90, is a rotor 120. Rotor 120 comprises a rotor wall 130 that is substantially cylindrical in form and rotor cap 140 being of substantially circular form. The rotor wall 130 and the rotor cap 140 have diameters of approximately 10cm and are coupled together to form an inverted cup shape, with their outer peripheral edges aligned. The rotor 120, and specifically the circular lower end of the rotor wall 130, rests on a rotor bearing disposed within the base plate 20, such that the rotor 120 is arranged to rotate about its axial length with respect to the containment vessel. Alternatively, the rotor bearing may be replaced by a series of rotor bearings. The drive shaft 90 projects from the centre of the rotor cap 140 such that rotation of the rotor 120 about its axial length causes rotation of the drive shaft about its axial length. The rotational axis of the rotor 120 is parallel to, and spaced from, the central axis of the containment vessel by approximately 1.4cm.

Disposed in the rotor wall 130, at an angular spacing of 90 degrees, are four slots 150. Through each slot 150 passes a respective vane 160. Each vane 160 is arranged to pass from substantially the central axis of the containment vessel to the inner surface of the containment vessel. The angular separation between each vane 160 is constrained by the angular rotational position of the rotor 120 about its rotational axis. Each vane comprises a substantially flat plate divided into an upper section, which is substantially rectangular in form, and a lower section, which is substantially rectangular in form, the upper and lower sections being separated by a gap of approximately 0.5cm. During use, the upper section will remain within the upper portion 40 of the containment vessel and the lower section will remain within the lower portion 30 of the containment vessel.

The divider 60 comprises a substantially flat plate with a circular outer profile having a diameter substantially equal to the diameter of the

cylindrical portions

30, 40, and with a circular inner profile having a diameter substantially equal to the diameter of the rotor wall 130. The rotor 120 is disposed within the circular inner profile of the divider 60. The divider 60 is arranged within the gaps of the vanes 160, such that the upper section of each vane 160 will be on an upper side of the divider and the lower section of each vane 160 will be on a lower side of the divider. The gaps of the vanes 160 provide a clearance of 0.1mm between the vanes 160 and the divider 60. Four passages 170 in the rotor wall 130 connect a region between the rotor wall 130 and the upper portion 40 of the containment vessel between two vanes 160, to a region between the rotor wall 130 and the lower portion 30 of the containment vessel between an adjacent pair of vanes 160.

Figure 3 is a perspective view of the heat engine 10 of figure 2, additionally with the divider 60 removed. The gaps between the upper section of the vanes 160 and the lower section of the vanes 160 can be seen.

Figure 4 is a simplified schematic representation of the heat engine 10 of figure 1.

Figure 5 is a perspective view of the heat engine 10 of figure 3, additionally with the rotor 120 removed. The slots 150 in the rotor 120 house vane sealing rods 180. Each vane sealing rod 180 is substantially cylindrical in shape and has a slit extending through a diameter of the rod 180, and along an axial length of the rod 180. Through each slit passes a respective vane 160. The vane sealing rods 180 are made from a low-friction material that allows them to rotate easily within the slots 150, allows for smooth sliding of the vanes 160 through the slits, and allows a fluid-tight barrier to the interior of the rotor 120.

Each vane 160 is rotatable around a vane shaft 190. Each vane is coupled to two respective vane clamps 200. Each vane clamp 200 comprises a ring-like member containing vane bearings 210 therein, configured to rotate about the vane shaft 190. Each vane clamp 200 further comprises a pair of opposing jaws that grip the vane 160 such that the vane 160 and the vane clamps 200 rotate about the vane shaft 190 as a single vane arrangement.

Figure 6 is a perspective view of the heat engine 10 of figure 5, additionally with the vane arrangements removed. The vane shaft 190 is centrally located on the base plate 20, and extends substantially perpendicularly from the base plate 20. An annular recess 220 in the base plate 20 provides means to retain the series of rotor bearings disposed within the base plate 20 upon which the rotor 120 is arranged to rotate.

Figure 7 is a perspective view of one of the vane arrangement of figure 5, having been removed from the heat engine 10, the vane arrangement comprising the vane 160, the vane clamps 200 and the vane sealing rod 180.

Figure 8 is a vertical section of the heat engine 10 of figure 1, along the line AA of figure 9. The rotor 120 rests on rotor bearings 230 located in the annular recess 220 in the base plate 20. Gaskets 240 are located around the bolt 100 at joins between adjacent components constituting the container vessel. Specifically, gaskets 240 are present between the base plate 20 and the lower portion 30, the lower portion 30 and the divider 60, the divider 60 and the upper portion 40, and the upper portion 40 and the cylinder head 50. The gaskets provide a fluid-tight seal such that working fluid may be retained in the heat engine 10.

Figure 9 is a horizontal section of the heat engine of figure 1, along the line BB in figure 8. The angular displacement of the vane sealing rods 180 around the rotor 120 is approximately 90 degrees. The angular separation of the vanes from one another varies around the rotor from a minimum of 72 degrees to a maximum of 117 degrees. Figure 9 shows the angular separation of the vanes in intermediate positions of 75 degrees and 105 degrees.

Working fluid is retained within the heat engine 10 due to the seals used, in particular the gaskets 240 the vane sealing rods 180 and the rotary seal 80. The remaining components of the heat engine are manufactured to fine tolerances such that substantial quantities of fluid will not leak from one part of a working region to another part of a working region. However, these fine tolerances may not lead to sealing of the same quality as the seals to retain working fluid within the heat engine. The clearance may be between approximately 0.05mm and 0.2mm, in particular between approximately 0.75mm and 0.15mm, preferably approximately 0.1mm.

Figure 10 is a series of horizontal sections similar to figure 9, illustrating the rotational position of the working regions throughout a full cycle. In particular, the upper series shows the upper portion 40 and the lower series shows the lower portion 30. A first part of a first working region 250 is indicated black in the upper series. A second part of a second working region 260 is indicated black in the lower series. The first part of the first working region 250 is connected to the second part of the second working region 260, which is 90 degrees behind the first working region, by a passage 170 that allows fluid communication between the two regions.

In the arrangement shown, the upper portion 40 is being heated and the lower portion 30 is being cooled, such that there is a net flow of heat from the upper portion 40 to the lower portion 30. In some embodiments, only a sub-portion of the upper portion is heated and only a sub-portion of the lower portion is cooled, such as half or a quarter. This flow of heat is used to turn the vanes 160, and thereby the rotor 120 and the drive shaft 90 in the manner described below.

0^o Almost all of the working fluid from the two parts is in the first part of the first working region 250.

Working fluid in the first part of the first working region 250 is heated. The working fluid increases in pressure, forcing the first part of the first working region 250 to expand. This drives rotation of the leading vane bounding the first part of the first working region 250 anti-clockwise, thereby turning the rotor.

45^o Most of the working fluid from the two parts is in the first part of the first working region 250.

Working fluid in the first part of the first working region 250 is heated. The working fluid increases in pressure, forcing the first part of the first working region 250 to expand. This drives rotation of the leading vane bounding the first part of the first working region 250 anti-clockwise, thereby turning the rotor. Some of the working fluid moves through passage 170 into the second part of the second working region 260.

90^o Most of the working fluid from the two parts is still in the first part of the first working region 250. The first part of the first working region 250 is at its maximum volume.

Working fluid in the first part of the first working region 250 is heated. The working fluid increases in pressure, forcing an increasing amount of working fluid through the passage 170 into the second part of the second working region 260. The second part of the second working region 260 is forced to expand. This drives rotation of the leading vane bounding the second part of the second working region 260 (i.e. the following vane bounding the first part of the first working region 250) anti-clockwise, thereby turning the rotor.

135^o The working fluid is approximately equally distributed between the first part of the first working region 250 and the second part of the second working region 260. The combined volume of the two regions is at a maximum.

Working fluid in the first part of the first working region 250 is heated. The working fluid increases in pressure, forcing an increasing amount of working fluid through the passage 170 into the second part of the second working region 260. Working fluid in the second part of the second working region 260 is cooled. The working fluid decreases in pressure, contracts and makes room for the additional fluid from the first part of the first working region.

180^o Most of the working fluid from the two parts is now in the second part of the second working region 260. The second part of the second working region 260 is at its maximum volume.

Working fluid in the second part of the second working region 260 is cooled. The working fluid decreases in pressure, contracts and pulls the following vane bounding the second part of the second working regions anti-clockwise, thereby driving the rotor. Some of the working fluid moves through passage 170 into the second part of the second working region 160.

225^o Most of the working fluid from the two parts is now in the second part of the second working region 260.

Working fluid in the second part of the second working region 260 is cooled. The working fluid decreases in pressure, contracts and pulls the following vane bounding the second part of the second working regions anti-clockwise, thereby driving the rotor. The remainder of the working fluid moves through passage 170 into the second part of the second working region 160.

270^o Almost all of the working fluid from the two parts is now in the second part of the second working region 260. The first part of the first working region 250 is at a minimum volume.

Working fluid in the second part of the second working region 260 is cooled. The working fluid decreases in pressure, contracts and pulls the following vane bounding the second part of the second working regions anti-clockwise, thereby driving the rotor. Some of the working fluid begins to move back through passage 170 into the first part of the first working region 260. The fluid may be compressed as the rotor 120 may continue to rotate under momentum.

315^o The working fluid is approximately equally distributed between the first part of the first working region 250 and the second part of the second working region 260. The combined volume of the two regions is at a minimum.

Working fluid in the first part of the first working region 250 is heated. The working fluid increases in pressure, expands, and may drive the leading vane bounding the first part of the first working region to move anti-clockwise, thereby driving the rotor 120 to rotate. Working fluid in the second part of the second working region 260 is cooled. The remainder of the working fluid passed through the passage 170 into the first part of the first working region 250.

360^o The cycle is complete.

Claims

A heat engine for converting thermal energy into mechanical work, comprising:

a substantially fluid-tight containment vessel having a containment vessel axis;

a plurality of vanes arranged to partition the containment vessel into respective working regions for holding a working fluid, the plurality of vanes configured to rotate independently of one another about the containment vessel axis, such that a leading face of each vane bounds a leading working region and a following face of each vane bounds a following working region;

at least one divider arranged to divide each working region into a first part and a second part, wherein the containment vessel is configured to allow heat to enter the first parts such that working fluid therein expands and to allow heat to be removed from the second parts such that working fluid therein contracts;

a plurality of passages, each passage associated with a respective vane such that the passage is arranged to provide fluid communication between a first part of a leading working region, and a second part of a following working region, wherein the plurality of vanes are arranged to rotate about the containment vessel axis in response to expansion of working fluid within the first parts, contraction of working fluid within the second parts, and flow of working fluid between the first parts and the second parts; and

a rotor configured to constrain rotation of each of the plurality of vanes relative to each other vane within a predetermined angular range and to rotate about a rotor axis in response to rotation of the plurality of vanes about the containment vessel axis, thereby producing torque for generating power;

wherein each working region has a volume that is variable between a predetermined maximum volume and a predetermined minimum volume, dependent upon a rotational position of the rotor.
The heat engine according to claim 1, wherein the containment vessel is substantially cylindrical in form.
The heat engine according to claim 1 or claim 2, wherein the heat engine comprises four vanes.
The heat engine according to any preceding claim, wherein the vanes are substantially flat.
The heat engine according to any preceding claim, wherein the vanes are arranged to be spaced from the containment vessel.
The heat engine according to any preceding claim, wherein each part of each working region is substantially fluid-tight.
The heat engine according to any preceding claim, wherein the first part of a working region is substantially the same length parallel to the containment vessel axis as the second part of a working region.
The heat engine according to any preceding claim, wherein the first parts are substantially the same length parallel to the containment vessel axis as the second parts.
The heat engine according to any preceding claim, wherein the rotor is substantially cylindrical in form.
The heat engine according to any preceding claim, wherein the rotor comprises slots in through which the vanes are arranged to pass, each of the plurality of vanes passing through a respective slot.
The heat engine according to claim 10, wherein each slot is provided with a vane sealing rod.
The heat engine according to claim 10 or claim 11, wherein the vanes are slidably received in the slots.
The heat engine according to any preceding claim, wherein the rotor axis is parallel to and spaced from the container vessel axis.
The heat engine according to any preceding claim, wherein the spacing between the wall of the rotor and the wall of the container vessel varies with angular position around the container vessel.
The heat engine according to any preceding claim, wherein the angular distance between adjacent vanes varies depending on the degree of angular rotation of the rotor about the rotor axis.
A method of converting thermal energy into mechanical work, comprising:

providing a heat engine for converting thermal energy into mechanical work, comprising a plurality of units connected in series in a loop such that a unit at one end of the series is connected to a unit at an opposing end of the series, each unit comprising: a first substantially fluid-tight region having a volume that is variable between a minimum volume and a maximum volume, the first region suitable for containing fluid therein, wherein each unit is configured to allow heat to enter its respective first region; a second substantially fluid-tight region having a volume that can be varied continuously between a minimum volume and a maximum volume, the second region suitable for containing fluid therein, wherein each unit is configured to allow heat to be removed from its respective second region; and a passage configured to provide a fluid connection between the first region and a second substantially fluid-tight region of the next unit in the series; wherein the heat engine further comprises a mechanical coupling, configured to move in response to variation of the volume of each of the first and second substantially fluid-tight regions;

expanding a first fluid-tight region of a first unit to a maximum volume and conveying fluid from the first region of the first unit through a passage of the first unit to a second fluid-tight region of a second unit, thereby causing the second region of the second unit to expand, in response to heating fluid within the first region of the first unit, when the second region of the second unit has a minimum volume;

contracting the first region of the first unit and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand, such that the combined volume of the first region of the first unit and the second region of the second unit expands to a maximum volume, in response to heating fluid within the first region of the first unit, when the first region of the first unit has a maximum volume;

contracting the first region of the first unit and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit, thereby causing the second region of the second unit to expand to a maximum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a maximum volume;

contracting the first region of the first unit to a minimum volume and conveying fluid from the first region of the first unit through the passage of the first unit to the second region of the second unit and the second region of the second unit is configured to contract, in response to cooling fluid within the second region of the second unit, when the second region of the second unit has a maximum volume;

expanding the first region of the first unit and conveying fluid from the second region of the second unit through the passage of the first unit to the first region of the first unit, thereby causing the second region of the second unit to contract, such that the combined volume of the first region of the first unit and the second region of the second unit contracts to minimum volume, in response to cooling fluid within the second region of the second unit, when the first region of the first unit has a minimum volume;

expanding the first region of the first unit and conveying fluid from the second region of the second unit through the passage of the first unit to the first region of the first unit, thereby causing the second region of the second unit to contract to a minimum volume, when the combined volume of the first region of the first unit and the second region of the second unit has a minimum volume;

wherein the mechanical coupling moves in response to variation of the volume of each of the first and second substantially fluid-tight regions, thereby producing mechanical movement for generating power.
A heat engine substantially as hereinbefore described with reference to the accompanying drawings.