GB2338034A - A non combustible expanding gas motor - Google Patents

Abstract

A motor comprises at least one chamber 4 having an inlet 17a for allowing the introduction of a working fluid from a fluid supply 5, an outlet 17b for allowing fluid to escape, a movable member 18 disposed within the chamber and means 21 for maintaining at least part of the chamber 4 at a higher temperature than that of the supply fluid so that in use the fluid entering the cylinder 4 absorbs heat energy and expands without combustion; the expansion causing the movable member 18 to move. Preferably the supply fluid is liquid nitrogen, the movable member is either a piston (1b, figure 1 and 3) or one or more turbine rotors 18. The chamber (figures 1 and 3) in which the nitrogen expands and the chamber (figures 1 and 3) in which the movable member is housed may be different chambers. The means 21 for maintaining the temperature of the expansion chamber may be a jacket forming a heat exchanger. Also disclosed is a cylinder head (figure 1) and injection means (figure 3) which provides the means for maintaining the temperature of the expansion chamber.

Description

2338034 1 Motors This invention relates to motors and methods of

generating motion. Such devices are typically used for 5 vehicle propulsion or the generation of electricity.

There are a number of existing types of engine and motor used for these purposes. The vast majority of these rely on internal combustion. Internal combustion engines have disadvantages because they rely on the use of diminishing resources and the by-products of the combustion include various noxious and undesirable substances. Such engines also create a large amount of waste heat which has to be dissipated.

Another type of existing engines are so called is "Stirling engines" which rely on using temperature differences to expand and contract an enclosed quantity of gas. The performance of Stirling engines is limited by a number of factors including the difficulty of removing the heat energy from the enclosed gas quickly in order to obtain a good power output.

It is an object of the present invention to provide a motor or a method of producing a motion which alleviates some of the problems associated with the existing engines described above.

2 According to one aspect of the present invention there is provided a motor comprising at least one chamber having an inlet for allowing introduction of fluid from a fluid supply and an outlet for allowing fluid to escape from the motor, and a moveable member which is disposed in the chamber, wherein means are provided for maintaining at least part of the chamber at a higher temperature than the fluid supply so that, in use, fluid entering the chamber absorbs heat energy and expands, without combustion, said expansion causing the moveable member to move.

According to another aspect of the present invention there is provided a method of generating motion comprising the steps of:

is maintaining the temperature of at least part of a chamber above that of a fluid supply, introducing fluid from the supply into the chamber, allowing the introduced fluid to absorb heat and expand without combustion, using said expansion to cause a moveable member disposed in the chamber to move, and allowing the expanded fluid to escape to the surroundings.

Preferably the fluid supply comprises fluid storage means for storing a fluid. The fluid storage means and 3 chamber can be arranged so that, in use, the storage means is maintained at a lower temperature than said part of the chamber.

The fluid storage means may be arranged to maintain the temperature of the stored fluid below ambient temperature. In such a case the fluid can be a liquified gas such as liquid nitrogen. As the liquified gas is allowed into the chamber it will boil, and consequently massively increase in volume, further increase in volume will occur as the temperature of the gas rises. Heat can be drawn from the surroundings of the chamber to provide the energy needed to boil and/or raise the temperature of the f luid. Preferably a heat exchanger system is provided for keeping the chamber within a suitable is temperature range.

Heating means can be provided for heating at least part of the chamber. The heating means can be arranged to raise the temperature of at least part of the chamber above ambient temperature. The heating means can be provided in addition to or as an alternative to providing a fluid storage means which maintains the temperature of the stored fluid below ambient temperature. Where heating means are provided, the fluid can be liquified gas or a gas which is gaseous at ambient temperature.

As the fluid enters that part of the chamber which is 4 heated, the f luid absorbs heat energy generated by the heating means and expands.

In each case the introduced f luid is relatively cool, is allowed to absorb heat energy and therefore expand before being allowed to escape. Because no combustion takes place little or no undesirable byproduct is generated. Further, because the expanded gas is allowed to escape there is no need to re-cool the gas for a subsequent cycle.

The moveable member may comprise a piston which is mounted for reciprocating movement. In such a case the motor may have the same general construction as a 2stroke internal combustion engine.

At least one valve can be provided at the inlet is and/or the outlet. A common valve can be provided to control both the introduction and escape of fluid. An inlet valve can be provided which has an open position in which f luid is allowed to enter the chamber and a closed position in which fluid cannot enter the chamber.

A choke valve for adjusting the rate of introduction of the fluid can be provided. The choke valve can be used to control the speed of the motor. The introduction of f luid can be controlled by an inlet valve and a choke valve.

The operation of valves at the inlet and/or outlet can be controlled via a mechanical arrangement which takes its drive from a crankshaft driven by the reciprocating piston. The mechanical arrangement can comprises a camshaft and/or a gear arrangement.

The introduction of fluid can be controlled by a fluid injection system. The injection system can comprise a magnetically coupled valve driven by electronic circuitry which is triggered by an engine position sensor. The injection system can be used to control both the quantity of fluid injected and the timing of the injection. In this way the fluid injection system can be used to control the speed of the motor.

The motor can comprise a cylinder head which is arranged for use with an existing automotive engine is block.

According to yet another aspect of the present invention there is provided a cylinder head for use in a motor according to the above aspects of the invention and which is arranged for use with an existing automotive engine block and which comprises an inlet for allowing introduction of fluid at below ambient temperature into a chamber defined by the cylinder head and engine block, a heat exchange system for maintaining the chamber within a suitable temperature range and an outlet for allowing fluid to escape to the surroundings.

6 Typically, where a reciprocating piston motor is used more than one chamber will be provided. In such a case it will be understood that any necessary valves, pistons and other means will be provided for each chamber.

In other developments of the invention, the motor may be a turbine unit and the moveable member may comprise at least one rotor of the turbine. A multistage turbine can be provided. The turbine may be used to drive an electricity generator. The escaping fluid can be used to cool the generator.

The fluid storage means can comprise at least one dewar or other vacuumlined container. The internal pressure of the dewar or other container can be maintained above atmospheric pressure. This can help to minimise boil-off and assist in injection of fluid into the chamber.

One or more safety valve can be provided to safely allow fluid at excess pressure to escape from the storage means andlor the chamber.

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

Figure 1 is sectional view of part of a first motor; 7 Figure 2 is a section on line II-II of the part of the first motor shown in Figure 1; Figure 3 is a partial sectional view of a second motor which has an alternative injection system; Figure 4 is a side sectional view of a third motor which is arranged as a turbine; and Figure 5 is a fluid supply system for use with a motor.

Figures 1 and 2 show a first motor which generally comprises a conventional automotive engine block 1 and a specially arranged cylinder head 2. The conventional engine block 1 comprises two cylinders la and two corresponding pistons lb.

The cylinder head 2 comprises a body 3 which defines a generally cylindrical expansion chamber 4. A vacuum shielded supply line 5 terminates in the expansion chamber 4 at an inlet 4a through which f luid can be introduced into the expansion chamber 4. The expansion chamber 4 also comprises a safety release valve 6.

Two rotary valves 7 (only one which is shown) are provided; one being associated with one of the cylinders la and the other being associated with the other of the cylinders la. Each of the rotary valves 7 is driven via an overhead bevel gear arrangement 8 which in turn 8 derives drive from the motor crankshaft (not shown). The gearing can be selected so that the rotary valves 7 rotate at any desired frequency. In the present embodiment the rotary valves 7 are driven at full crankshaft speed.

The cylinder head body 3 further defines two generally cylindrical inlet tracts 9 which lead from the expansion chamber 4 to the rotary valves 7. One of the inlet tracts 9 is associated with one of the rotary valves 7 and the other inlet tract 9 is associated with the other rotary valve (not shown). Butterfly choke valves 10 are provided in each of the inlet tracts 9.

Two exhaust ports 11 (only one of which is shown) are provided in the cylinder head body 3 each being disposed opposite to a respective one of the inlet tracts 9 with the respective rotary valve 7 being disposed therebetween.

Each rotary valve 7 is provided to allow the passage of fluid from the expansion chamber 4 to the respective cylinder la and out through the respective exhaust port 11. Each of the rotary valves 7 is shaped as a generally hollow cylinder with a closed upper end 71, an open lower end 72 and an aperture 73 formed in part of the curved surface of the cylinder. O-ring seals 0 are provided at the upper and lower ends 71, 72 between the curved 9 surf ace of the rotary valve 7 and a corresponding mating surface of the cylinder head body 3. The aperture 73 is positioned and dimensioned so that as the rotary valve 7 rotates it can provide an inlet path for fluid supplied from the inlet tract 9 and an outlet path for fluid to escape through the exhaust port 11.

When the rotary valve is in an inlet position, a path is formed from the respective inlet tract 9 through the hollow body of the rotary valve 7 and out through the open lower end 72 into the respective cylinder la.

When the rotary valve 7 is in an outlet position a path is formed from the respective cylinder la through the open lower end 72 into the hollow body of the valve 7 and out through the aperture 73 to the exhaust port 11.

A heat exchange system is provided which comprises a jacket i which surrounds that part of the cylinder head body 3 in which the expansion chamber 4 is located. The jacket J is arranged to contain a volume of a Glycol solution which can be circulated and draw heat energy from the surroundings of the motor, that is, from the atmosphere.

In operation, liquid nitrogen is fed from an appropriate storage tank through the vacuum-shielded supply line 5 into the expansion chamber 4. on entering the chamber 4, which is at a temperature well above the boiling point of liquid nitrogen, the nitrogen boils and therefore tends to expand. Further, as the temperature of the gas is raised further expansion tends to take place. Because this occurs in a relatively confined space high pressure is generated. The safety valve 6 is provided so that it will allow the expanding gas to escape should the pressure exceed a desired maximum.

As the gas expands it will tend to be driven down the inlet tracts 9. However unless one of the rotary valves 7 is located so that its aperture 73 is at least partially aligned with one of the inlet tracts 9 none of the expanding gas will be allowed to escape.

In the present embodiment where two cylinders la are provided, the pistons 1b are arranged to run in antiphase is and correspondingly the two rotary valves 7 will be in antiphase. Therefore, when one of the rotary valves 7 is positioned so that its aperture 73 is at least partially aligned with its respective inlet tract 9, the other rotary valve 7 will be positioned so that its curved surface blocks the end of its corresponding inlet tract 9.

When one of the pistons 1b is at the top of its travel, the aperture 73 of the respective rotary valve 7 will be aligned with the inlet tract 9 so that the expanding nitrogen gas can travel from the expansion 11 chamber 4 through the inlet tract 9 and the hollow body of the respective rotary valve 7 to meet the upper surface of the respective piston lb. The pressure of the expanding gas forces the piston lb downward to generate mechanical motion. The pathway through the rotary valve stays open for a period defined by the positioning and dimensioning of the aperture 73 and during this period the expanding gas continues to drive the piston lb downwards. At a later time in the cycle, the aperture 73 no longer aligns with the inlet tract 9 and no more gas is allowed to enter the cylinder la. As the piston lb reaches the bottom of its travel, the aperture 73 aligns with the respective exhaust port 11 so that, as the momentum of the engine (and the power acting on the other piston lb) causes the piston lb to rise, the expanded and heated gas can escape through the hollow body of the rotary valve 7 and the exhaust port 11 to the atmosphere. This cycle is then repeated in that cylinder la. 20 It will be appreciated that a similar cycle simultaneously occurs, in antiphase, in the other cylinder la. This is essentially a 2-stroke action so that with two cylinders power is generated on every stroke. 25 The speed of the motor will be dictated by the 12 amount of expanding gas which is allowed to act on the pistons lb. In the present embodiment although the liquid nitrogen is fed at an essentially constant rate through the supply line 5, the choke valves 10 can be operated to restrict the flow of the expanding gas into each of the cylinders la. In this way the choke valves 10 can be used to control the speed of the motor. The choke valves can be connected by a cable to a lever or pedal which can be operated by a user in a conventional manner.

As the motor is run the heat exchange system operates to keep the body 3 of the cylinder head within a suitable temperature range. This ensures that the liquid nitrogen supplied to the expansion chamber 4 continues to boil and expand.

is Figure 3 shows a second motor which again is arranged to be driven by the expansion of liquid nitrogen but which has alternative forms of inlet and exhaust mechanisms. Again the motor comprises a conventional automotive engine block 1 having one or more cylinders la and one or more pistons lb and a specially arranged cylinder head 2. In this embodiment a liquid nitrogen injection system 12 is provided to allow the introduction of liquid nitrogen into the respective cylinders la.

A vacuum-shielded supply line 5 is provided from an 25 appropriate fluid storage means (not shown in Figure 3) 13 and terminates at an inlet 4a disposed in a small volume def ined between an upper surface of the respective piston 1b and the cylinder head 2. This small volume acts as an expansion chamber 4.

The fluid injection system 12 is provided to control the flow of fluid through the supply line 5 before it reaches the expansion chamber 4. The fluid injection system 12 is a magnetically coupled injection valve system which is driven by electronic circuitry which in 10 turn is triggered by an engine position sensor such as a contact breaker. The injection system comprises a coil 12a which surrounds the supply line 5 and a magnetic core 12b, disposed within fluid supply line 5 to which a valve disc 12c is connected via a rod 12d. Holes are provided is through the core 12d to provided a passage for the fluid which is to be injected. The magnetic interaction between the coil 12a and core 12b is used to move the valve disc 12c towards and away from its seat 12e, thereby controlling the flow of fluid through the supply 20 line 5.

The fluid injection system 12 controls the amount of fluid which is injected into the cylinder lb and the time at which this injection takes place. Thus the fluid injection system can be used to control the speed of the 25 motor as well as ensuring that the fluid is provided at 14 the correct times.

Escape of expanded and heated gas is allowed via an exhaust port 11 which is controlled by a conventional valve 13 operated by a cam and follower 14 and 15 which take drive from the motor crankshaft (not shown).

In operation liquid nitrogen is injected into the expansion chamber 4 when the respective piston lb is at the top of its travel. As the nitrogen enters this volume it boils and therefore tends to expand. Further expansion tends to take place as the temperature of the gas is raised. This generates high pressure which drives the piston 1b downward to allow the gas to expand. As the piston reaches the bottom of its travel the exhaust valve is opened so that as the piston lb rises due to the engine momentum (and drive on other cylinders) the expanded nitrogen escapes through the exhaust port 11.

A heat exchange system is provided which circulates a Glycol solution through internal chambers 16 in the cylinder head 2 and engine block 1 to maintain the structure within a suitable temperature range.

The speed of the motor can be controlled by the user operating a throttle which in turn causes appropriate signals to be sent to the fluid injection system 12.

Figure 4 shows a third motor arranged as a turbine which can be driven by liquid nitrogen as it boils and is expands. The motor generally comprises an outer housing 17 having an inlet 17a at one end and an exhaust 17b at the other end and in which a multi-stage turbine is disposed. A vacuum-shielded supply line 5 is connected to the inlet 17a which opens into an expansion chamber 4 defined within the housing 17.

The turbine comprises several rotor discs 18 (three of which are shown) mounted on an output shaft 19. The rotor discs 18 are successively geared down by gearing 20 in such a way as to capture as much energy as possible from the gas as it loses pressure on its way to the exhaust 17b.

A heat exchange system is provided and this comprises a chamber 21 through which a Glycol solution can be circulated to supply heat energy from the surroundings. This ensures that the housing 17, and in particular the expansion chamber 4, are maintained at a suitable temperature.

In operation liquid nitrogen is supplied through the supply line 5 into the expansion chamber 4. once the liquid nitrogen reaches the expansion chamber 4 it boils and expands. The expanding gas is then driven through the multistage turbine and exits through the exhaust 7b. The output shaft 19 is used to drive an electricity generator (not shown) and the escaping nitrogen is caused 16 to pass across the generator (not shown). This can provide a cooling action and the f low of inert gas provides other advantages such as reducing fire risk and brush burn.

In each of the above embodiments liquid nitrogen must be stored in a suitable container for supply to the motors. If the motors are to be used in a static position then standard dewars can be used. However if the motors are to be used in a mobile apparatus, f or example a vehicle, then it is preferable to use a specially arranged storage tank and supply system.

Figure 5 shows such a storage tank and supply system. The system comprises a vacuum-lined tank 101 which is kept at high pressure to minimise boil-off and provide an initial pressure for delivering the nitrogen to the expansion chamber(s) of the desired motor. Baffle plates 102 are provided within the tank 101 to minimise movement of the liquid nitrogen during vehicle motion. A pressure safety valve 103 is provided in the tank to allow any excess pressure which develops to escape. The vacuum-shielded supply lines 5 from each of the expansion chambers 4 connect with a main vacuum-shielded line 5 which is supported in an outer casing 104 throughout the vehicle and terminates inside the vacuum-lined tank 101.

As shown in the enlarged portion of Figure 5 the supply 17 line 5 is supported within the outer casing 104 by multipronged clamps 105 which are arranged to keep heat transfer to a minimum. Typically the pressure in the vacuum-lined tank is maintained at approximately two atmospheres or above.

Although it is envisaged that motors as a whole can be constructed as described above with respect to Figures 1 to 4, it is particularly advantageous when the cylinder heads of the motors described with respect to Figures 1 to 3 are made such that they are suitable for fitting to existing standard car engine blocks.

It is envisaged that the heat exchange systems of the first, second and third motors can be used to keep the motors and in particular the expansion chambers 4 at approximately 0 Centigrade.

It will be appreciated that the gas exiting from the motors will typically be below ambient temperature and therefore can in some circumstances be useful as a coolant.

1 119

Claims (1)

1. CLAIMS: 1. A motor comprising at least one chamber having an inlet for

   allowing introduction of fluid from a fluid supply and an outlet for allowing fluid to escape from the motor, and a moveable member which is disposed in the chamber, wherein means are provided for maintaining at least part of the chamber at a higher temperature than the fluid supply so that, in use, fluid entering the chamber absorbs heat energy and expands, without combustion, said expansion causing the moveable member to move.

   2. A motor according to Claim 1 in which the fluid supply comprises fluid storage means for storing a fluid, said fluid storage means and chamber being arranged so that, in use, the storage means is maintained at a lower temperature than said part of the chamber.

   4.

   3. A motor according to Claim 2 in which the fluid storage means is arranged to maintain the temperature of stored fluid below ambient temperature.

   A motor according to Claim 3 in which the fluid 161 is a liquified gas such as liquid nitrogen.

   5. A motor according to any preceding claim further comprising heating means for heating at least part of the chamber.

   6. A motor according to any preceding claim in which the movable member comprises a piston which is mounted for reciprocating movement.

   7. A motor according to any one of Claims 1 to 5 in which the motor is arranged as a turbine unit and the movable member comprises at least one rotor of the turbine.

   8. A motor according to Claim 7 in which the turbine is used to drive an electricity generator and in use the escaping fluid is used to cool the generator.

   9. A motor according to any preceding claim further comprising a common valve for controlling both the introduction and escape of fluid.

   10. A motor according to any preceding claim in which 25 the introduction of fluid is controlled by a fluid 620 injection system.

   11. A cylinder head for use in a motor according to any one of Claims 1 to 10 which is arranged for use with an existing automotive engine block and which comprises an inlet for allowing introduction of fluid at below ambient temperature into a chamber defined by the cylinder head and engine block, a heat exchange system for maintaining the chamber within a suitable temperature range and an outlet for allowing fluid to escape to the surroundings.

   12. A method of generating motion comprising the steps of:

   maintaining the temperature of at least part of a chamber above that of a fluid supply, introducing fluid from the supply into the chamber, allowing the introduced fluid to absorb heat and expand without combustion, using said expansion to cause a moveable member disposed in the chamber to move, and allowing the expanded fluid to escape to the surroundings