DE2820526C2 - Hot gas reciprocating engine with electromagnetically driven displacer - Google Patents

Description

The invention relates to an externally heated hot gas reciprocating engine with an electromagnet driven light displacer, which can also s * in heat exchanger. In other words, it is a simplification of the still complex control and regulation of the since 162 Hot gas (Stirling) engine known for years.

With decreasing energy sources, the general tendency is to use primary energy, i. H. gaseous, liquid or solid fuels or other heat sources or energy carriers are more economical for extraction of mechanical and / or thermal energy, especially in many cases the detour via the To save electricity company with its energy loss of around two thirds.

The Stirling engine has been known since 181 ^. Since 1938 got it from Philips Gloeilampenfabrieken, Eindhoven-Netherlands, too high speed, power, smoothness. Lifespan. Exhaust cleanliness, too high efficiency and further developed to the lowest possible lubricating oil consumption. Motortechnische Zeitschrift (MTZ) 1968, pages 284.,. 289. Others too, such as Maschinenfabrik Augsburg Nürnberg (MAN) and Motorenwerke Mannheim (MWM), United Stirling in Sweden, and Ford in the USA have reported development successes. MTZ 1972. Pages 67 / 6Ü and 489, pages 264/265 and 1975. Pages 185/186. Also a free piston Stirling engine after William T. Beale is the Sunpower Incorporated. Athens, Ohio 701, USA became known.

However, the technical effort involved in these solutions is high. The Philips design requires a multi-part Mechanics, because in addition to the working piston there is a second cylindrical body, the displacer, out of phase must be moved to the piston. The displacement rod must be gas-tight by piston and Piston rod are guided. There are also known designs without displacer, but several tight require adjacent single or double acting cylinders. In the extraction of mechanical Energy is disadvantageous in that there are very large coolers, since there is about twice as much waste heat, this possibly at a much lower temperature through which the cooling liquid has to be discharged than with gas or diesel engines.

Beale's proposal contains the compulsion to

rhythmic function with a frequency between 20 and 30 Hz ₁ which can only be changed within small limits by changing the power output and the filling or average working pressure.

The invention has for its object to simplify the hot gas engine so that it is less Construction costs and maintenance than the conventional internal combustion engines claimed that it is quieter and otherwise more environmentally friendly than this one and has a service life that is several times as long.

This object is achieved according to the invention in that, starting from an externally heated Hot gas reciprocating engine with an electromagnetically driven light displacer, which at the same time Heat exchanger can be at least one coil to drive the displacer outside the cylinder Generating one or more magnetic fields is attached through the thin cylinder wall act on magnetizable parts of the displacer.

In a hot gas reciprocating engine with a preferably vertical cylinder can be advantageous Further development of the light displacer from a thin-walled at its hot end to its cold end increasingly stronger cylinders consist of magnetically influenceable material, with a certain accumulation of material in the part which is in the position of the displacer adjacent to the hot end of the cylinder is held in the core of the magnetic field.

A coil to which current pulses are applied is advantageously provided outside the cylinder and the displacer is equipped with ferromagnetic parts. But it can also be done with one with a current pulse. acted upon coil outside of the cylinder of the displacer wear short-circuit conductor.

The circuit or circuits for generating magnetic fields for displacement movement can be of a speed-controllable time switch can be switched on and off.

Instead of a coil, a plurality of individual coils arranged outside H ° s cylinder can be used be provided for generating a traveling electromagnetic field.

Means for pulse reversal can also be provided.

It is also advantageous to have at least one of the forehead visions facing one another in one To arrange cylinder located displacer and working piston permanent magnets. In addition, for the delivery of the work for a longer movement of the displacer a spring / be provided.

The displacer, which can also be designed as a heat exchanger, contains a heat exchanger for this purpose Made of light, highly thermally conductive material with a high thermal capacity, through which the working gas flows coaxial bore has a high-profile, steep-running swirl-generating internal thread.

To dampen or brake the movement of the displacer in its end positions, corresponding Damping means can be provided, preferably the permanent magnets on the end faces of the displacer or working pistons can be designed as damping means in the form of rubber-elastic magnets. It can but also as a damping means a cylinder-piston combination at least on one end face of Displacer and / or working piston may be provided.

To achieve an absolute mass balance without the usual mass balancing means and for simultaneous electromagnetically or electrodynamically induced movement of two displacers Finally, two hot gas reciprocating engines of the form described above are coaxially assembled be.

DE-OS 26 53 455 discloses a hot gas piston machine from the Philips Gloeilampenfabrieken already mentioned at the beginning become known, in which magnetic fields are generated outside the cylinder, in the but the working piston with the electromagnetic one

ίο Field interacts, but not the displacer. In the Movement of the displacer is only a matter of low pressure losses and friction overcome, i.e. exclusively about the introduction of the lowest tax payments. At the machine after the In contrast, the DE-OS mentioned, as well as numerous other comparable solutions, are large, bulky and heavy fixed magnets are required. In the known embodiment, there is also an electromagnetic one Drive option provided for the displacer. Here, however, the influence of an electromagnetic Alternating field is not exerted by a thin cylinder wall on a slight displacer, which the Rather, an additional displacement rod is provided, which is sealed * after is guided outside, with the anchor coil provided there not stationary, but because with the Displacer rod connected, is movable. The fundamentally to strive for if not necessary full hermeticity in such machines it is the well-known one

jo machine not possible. Finally the displacer follows the known machine of a sinusoidal movement, while the displacer according to the invention carries out sudden changes in movement. This is only possible with the structure according to the invention of a hot gas

3, reciprocating engine ?, possible. This is where the control takes place the coil provided around the displacer outside the cylinder via capacitor discharges. The electromagnetic influence of the displacer through a thin cylinder wall is ultimately not possible with the known machine because it is necessary is surrounded by heat exchangers, namely a cooler and a regenerator

The new hot gas engine is initially to be designed for low power and speed. Frequently ^; g it should work with a free-swinging piston, i.e. without a crank drive and flywheel. Then it is better to speak of frequency or oscillation rate (Hz. Ms) instead of speed. When the working piston of the engine is directly coupled to linearly oscillating parts of any machine, these parts are free from transverse forces and the wear caused by transverse forces.

A.η the simplest is the drive of pumps with the new engine.

The power requirement of the pump piston runs evenly over the entire stroke. and for the piston reversal points (»Dead points« in the crank drive), a high level of accuracy is not sprung.

It is more difficult, but also far more rewarding because there are extensive areas of application here Drive single or multi-stage compressors, for example for generating compressed gas, for refrigerating machines or Heat pumps, also for cooling and heating simultaneously. The combination of hot gas reciprocating engine and heat pump is ideal because the Motor requires particularly good cooling for good efficiency and because the heat pump (as waste)

supplies ice-cold coolant. In addition, almost all of the waste heat from the hot gas reciprocating piston can be in be introduced into the heat cycle.

In the case of the compressor drive for cold or heat generation, the hot gas piston cylinder should If possible, the same agent is used in the refrigerant circuit and in buffers if the Working spaces are adjacent and are only separated from one another by sliding seals. It shouldn't Can blow foreign matter through into the refrigerant. As a chemically and thermally resistant refrigerant is being brought up for consideration:

Propane C) He,

Propylene C) H ₆ ,

Octafluorocyclobutane C4F8.

Sulfur hexafluoride SFe,

Carbon dioxide COj and others.

But there are also upper temperature limits for these substances, to whom they begin to rush and Attack materials or lubricants. If one wants to exceed such temperature limits, then for the hot gas engine uses an inert gas and conventional refrigerants can be used for the compressor will. This is problem-free as long as the hot gas engine is separated from the refrigerant-carrying rooms.

Great importance is attached to heat recovery from the hot exhaust gas to preheat the combustion air placed. Because the primary energy, which has been converted into mechanical energy, can be used in the heat pump with a factor, the so-called coefficient of performance, which is around 3 with the usual temperature spread, is back in sensible warmth can be converted back.

Unlike conventional hot gas engines, the displacer does not move sinusoidally like the piston, but quickly, almost instantly, while the free-swinging piston stands still in one end position. So you can get very close to the theoretical circular process and have a larger work surface with pronounced Reach corner points. In previous designs, this trapezoidal surface degenerated into ovals. Average higher, more complete work surfaces can also be an unusual feature of some of the bring mentioned heavy gases, their lower adiabatic exponent.

For the national economy is the saving of primary energy through the environmentally friendly invention significant. It has the following advantages for the individual user:

Savings in energy, electricity costs, and above all in supply costs for electrical power. "It doesn’t matter whether it is cold or heat recovery or Used to generate mechanical energy, the invention can also be used in remote areas remote from electricity be used where methane-containing gas from digesters is also used as fuel can. Heating by solar heat is also conceivable. As far as the energy in the tropics for cooling residential, If work rooms, storage rooms or stables are needed, the cooling requirement and solar heat supply fall in time together. The low electrical power to drive the displacer and to supply the Monitoring devices can come from in-house power generators, photocells or with waste heat from the engine heated thermocouples.

The following description is based on the attached schematic and examples Drawings various Ausfühnmgsformen of the hot gas Hulb piston engine according to the invention explained.

Fig. 1 shows the desired ideal pressure-volume diagram,

F i g. 2 gives the basic structure of the hot gas reciprocating engine again,

F i g. 3 shows a detail of the motif with movement of the Displacer through a moving field,

F i g. 4 shows a motor section with movement of the displacer by ferromagnetism,

Fig. 5 is a section with movement of the displacer by mutual induction.

F i g. 6 and FIG. 7 show an engine section with Stop damping and spring-fixed magnet combination in two positions,

F i g. 8 finally shows an embodiment as a pistonless conveyor.

The exemplary embodiments are illustrated in FIG. 1 by the “SEchlosssne inner gas cycle process” as a pressure-volume (PV) diagram prefixed. It is drawn for a compression ratio

n & t). . _{fn) = 2}

Kj (top dead center)

for a temperature relationship

T ( hot)
~ 7 "Γ (cold)

= r (tau) =

800 K (527 ⁰ C)

320K (47 ° C)

2.5

and for a maximum pressure of 100%. From the bottom dead center (or piston reversal point), the working gas is compressed from the cold temperature 7Ί = 320 K _{1 to} the volume V, and the pressure P \ = 20% to the volume Vj. V * is the displacement.

Depending on the piston speed, this change of state is more isothermal (exponent η = 1) or more adiabatic (exponent π = Ar (Kappa) = 1.4). The real polytropic change of state lies between isotherms and adiabats. The end temperatures are also given for both curves. After the displacement movement, the working gas is heated to 800 K in the hot room, the peak pressure Pi = 100% is established. In the following working stroke, again running between isotherm and adiabatic, the gas expands again to the volume Vi, the temperatures are given again. After the displacement movement, the gas cools down to 320 K, the pressure drops to Pi = 20%.

The curves apply to ideal gases with the adiabatic exponent # (Kappa) = 1.4. But help in Considered heavy gases lower exponents, from 1.14 (C3H8) down to the extremely low value 1.02 (SFe). That means that the work surface is against the Isotherms increases so that the pressure difference between compression and expansion becomes greater. Around Difficulties with high temperatures can also be reduced with lower temperatures (but same temperature ratio), around 750 K / 300 K.

Fig.2 shows the basic structure of the new Hot gas reciprocating engine. A heater 1 surrounds the hot space, a heat sink 2 surrounds the Cold room. 3 is an engine piston, 4 is a light displacer, here at the same time a heat exchanger. 5 is a thin-walled cylinder made of magnetically permeable material. Around it is about halfway up Magnetic coil 6, from a force line element 7

surround. The light displacer 4 consists of a thin-walled at its hot end, according to his cold end towards stronger magnetizable tube 8, which at its cold end just so much and so distributed material contains that the flow fins see Solenoid 6 lift the displacer 4, gently at the top, if possible without the need for a suspension let it hit and hold it in this position can. The movements of the displacer 4 are through the dense, high pressure gas and through narrow gas paths dampened.

In the case of a vertical cylinder 5, only a single magnetic coil 6 is usually necessary. Horizontal or inclined designs are possible, but are used here because of the additional friction and the higher Expenditure for the displacement movement not shown. The displacer 4 can be a heat exchanger 9 included, which should always be hot at the top and always cold at the bottom with the vertical arrangement shown. He consists of light, good heat-conducting material with high heat capacity around the heat flow lengthways To complicate its axis, disks 10 made of heat-insulating material can be inserted into parting lines be. The working gas flows through it through a coaxial bore 11. to enlarge the heat exchanging Surface and a high-profile, steep internal thread 12 or for generating twist may contain other agents promoting this effect.

In Fig. 2 is the top dead center position of the piston 3 drawn, the displacer 4 was already raised during the previous compression stroke, the Working gas has cooled down, its pressure has fallen to the lowest value / Ί. At the right time, the solenoid will 6 switched off, the displacer 4 falls to the piston 3 and slides with it during the working stroke this down.

The displacement movement can also be amplified electromagnetically or it can be effected electromagnetically alone. During the downward movement, the displacer 4 drives the cold working gas upwards. This flows preheated into the hot space, leans against the hot walls of the heater 1 and the cylinder 5 with a twist, quickly reaches its maximum temperature T) and its maximum pressure Pj and pushes the piston 3 downwards. When the bottom dead center is reached, the solenoid 6 is energized again, the slight displacer 4 is raised, the hot working gas is pressed down through the heat exchanger 9, heating it up and cooling itself, with a twist against the inner surface of the heat sink 2 and the cold piston head , cools down further and assumes the lowest pressure Pi . In this exemplary embodiment with a small displacement and high gas density, the heating and cooling chambers are indicated only with smooth inner surfaces. Models with a larger displacement and higher frequency make it necessary to enlarge the heat-transferring surfaces using conventional means, such as ribs or piping. Fine restoring force from the buffer and / or flywheel pushes the piston 3 back into its top dead center position. This ends a work cycle

The next one can be called up after any time interval, at least with the free-swinging piston, rhythmic operation is possible. This is also the case with low power and therefore a low frequency or Schwingzah !, every game under YoH-Lasi conditions and with VoD load efficiency.

This also results in the advantageous possibility when using the invention as a compressor suction and pressure side pipes for gas column vibrations so to agree that an increased level of funding arises. Such a procedure is z. B. known from the operation of Dual-stroke combustion engines, where however the Has the disadvantage that if the tuning speed is favored, other speeds are at a disadvantage. With Such coordination can achieve considerable values. So it succeeded z. B. in marine diesel engines, of which only a narrow speed range was required, the entire gas change without to carry out other funding facilities.

A temperature sensor 13 is located in or on the radiator 1 arranged from which the heating is controlled.

In the exemplary embodiment shown, gas is used for heating, which is fed through a ring burner 14 and burns with highly preheated air. The hot combustion gases flow between heating ribs or through the heating bores 15 through the radiator!, then dur.-h those inserted into the heating bores 15 Fin tubes 16 of the air preheater 17. The fresh air comes from above and is fed through a filler body 18 pushed out between the fin tubes 16 through, flows between the radiator 1 and a outer heat-insulating jacket tube 19 further down and flows through holes 20, preheated to a high level to the flames. The cooling water enters the heat sink 2 tangentially at 21, flows in a circling downward direction and exit at 22.

F i g. 3 shows in detail how the inventive Movement of the displacer 4 carried out by electromagnetic means with a traveling electric field will. For this purpose, the single coil 6 from FIG. B. three Sputen 55, 56 and 57 divided There can also be more coils in a manner known from the »linear motor«. The displacer 4 is equipped with induction rings 64 in a magnetic connection body 65. The induction rings 64 can also be passed through a pipe, e.g. B. a copper pipe be replaced. Starting from the upper position of the displacer 4 shown on the right, one after the other the switches 61, 62 and 63 briefly z. B. connected to capacitors 58, 59 and 60, with a Moving field running from top to bottom is generated, which moves the displacer 4 downwards reverse switch closing sequence, the displacer can be moved in reverse. The electromagnetic Traveling field can also be generated several times in succession or z. B. from a three-phase generator be fed at a suitable frequency.

4 shows an example of how the Movement according to the invention of the displacer 4 by means of ferromagnetic rings 66 and 67 at its ends hen. is called. Starting from the upper position of the displacer 4 shown on the right, the switch 68 to a suitable power source e.g. B. a capacitor 70 is connected. The resulting magnetic field moves the displacer 4 downwards. When it has covered about half its way, the switch 68 open after which the displacer 4 moves on with Massewirkun.g until it rests on the motor piston 3 Both move together as a result of the change in state of the working gas that has now taken place below in the position shown on the left. Now the switch 69 is closed and that in turn is produced Magnetic field moves the displacer 4 upwards. This movement goes over a larger stroke than that previously described movement, so requires higher electrical

shear drive power. Therefore, the switch 69 closes z. B. on two capacitors 71. Also for this Movement means that the magnetic field is switched off after about half of the required displacement stroke is, after which the lifting rest is covered under the action of mass.

F i g. 5 shows in detail how the movement according to the invention .ies displacer 4 by short-circuit rings 72 and 73 is evoked at its ends. Except for the effect of these short-circuit rings 72 and 73, which by Short-circuit induction cause an opposing magnetic field • and not drawn into the coil 6, but on these are pushed out and therefore remain pushed in over the center of the coil in both end positions the function is the same as in FIG. 4 described.

For Fig.4 and 5 applies equally that the »Nimplied. from an arbitrary QiipIIp gplnrlpnpn Knndpns.itnrpn 70 and 71, not shown lesser power sources can be replaced. However, they have the advantage of specific suitability for deployment short-term high current surges and can easily with the inductance of the coil 6 and inevitably given ohmic resistances of the circuit so that the switches 68 and 69 are not at full current flow or even only after the capacitors have been completely discharged.

F i g. 6 and 7 show a permanent magnet 74 on the displacer 4. There is also a helical spring S2, here surrounding the engine piston 3 in an annular gap, arranged in the cylinder. Permanent magnet 74 and coil spring 82 cooperate so that only high the short displacement movement electromagnetically must be triggered. In Fig. 6, the displacer 4 and the motor piston 3 are in their uppermost position "Cold compressed working gas" position. In this initial position, the permanent magnet 74 causes the now acting as a pole piece iron ring 75 on the displacer 4, that this is pulled up or there is held if the coil spring 82, as shown by way of example, does not force the position

If the coil receives 6 ^ a current pulse, the The resulting electromagnetic field of the displacer 4 is guided downwards against the motor piston 3 the coil spring 82 is slightly pretensioned until the permanent magnet 74 adheres to the engine working piston 3 At the same time, it is refreshed to the highest field strength. During the movement of the motor piston 3 that now follows Displacer 4 downward, the helical spring 82 is further biased until the position in FIG. 7 is reached Here the turns of the helical spring 82 lie on top of one another, so it is highly pretensioned and can cannot be squeezed any further. A slight further movement of the motor piston 3 is sufficient to cancel the magnetic adhesion of the displacer 4 to the motor piston 3. The now highly biased Helical spring 82 moves the displacer 4 quickly away from the engine piston 3 and causes the Return to the starting position according to Fi g. 6th

In Fig. 6 and 7 are further short hollow cylinders 76 and 77, with these cooperating short pistons 78 and 79, as well as springs 80 and 81 arranged in these shown. These parts form stop dampers for the Movement end positions of the displacer 4. Is this z. B. in his movement against the Atbeitsko'-ben 3, the short piston 79 dips into the cylinder 77 shortly before the stop. The annular gap between the short piston 79 and the wall of the short cylinder 77 is chosen so that the captured Working gas can only escape by overcoming a correspondingly strong flow resistance. the Movement of the displacer 4 is just before the

ι Stop braked. The short pistons 78 and 79 can also be completely or partially conical. The damping can be influenced in this way. the Springs 80 and 81 are provided in order not to be useless at the beginning of each movement of the displacer 4

to waste in performance. They allow a short-term Lifting the short piston 78 and 79 from their support surface and thus a free flow of gas into the Steam room. The permanent magnet can also be used as a rubber magnet made of magnetic powder in a soft binding material be formed and then serves as a stop buffer fer itself.

The coil spring 82 can also be omitted in the described embodiment with a permanent magnet, when the upward movement of the displacer 4 is also caused by an electromagnetic pulse initiated and carried out. It is then only the upper end of the displacer 4 with a To equip iron. The permanent magnet 74 then causes the displacer 4 to collapse

as moves down with the working piston 3 when this experiences an acceleration over 1, or if the device is operated in the reverse "up - down" direction or horizontally. It can be both Equipment can be provided at the same time. For the

jo normal operation then suffices the effect of the Permanent magnets and the coil spring. The iron ring at the upper end of the displacer 4 is safe Available when, for example, in a crankless free-flight compressor when starting the Working piston should not have moved all the way down, so that there is play between magnet and coil spring was not triggered.

A special embodiment of the inventive concept, namely as a conveyor without a working piston is shown in Fig.8. The coil 6 in turn generates a Brief magnetic field which is switched off at approximately half the stroke of the displacer 4. When moving the helical spring 82 is tensioned in the end portion of the movement of the displacer 4 downward this one valve slide 83 and moves it while tensioning its spring 84 downward. Be there Passages 85, e.g. B. released in the form of radially arranged bores in the cylinder housing. That through Increase in temperature, pressure-increased working gas enters a collecting duct 86, which it passes through an outlet nozzle 87 leaves for this purpose, it flows through the passages 11 of the largely releasing its heat Displacement heat exchanger 4 and the passages 88 corresponding to these in the iron ring 89.

At the same time, the gas holds the springs 82 through the force resulting from the given flow resistance and 84 under tension until the thermodynamic energy is exhausted. Then the springs can move relax. The spring 84 closes the valve slide 83 and the coil spring 82 moves the Displacer 4 back to its starting position. The residual gas content from the radiator passes through the passages 11 with heat dissipation, leaves it in a rotating whirling motion into the cold space and cools down there further pressure reduction. An inlet valve 90 opens and a new one enters via an inlet connection 91 Filling a. Another work cycle can be initiated.

S Rlofi

Claims (14)

Patent claims: 1. Externally heated hot gas reciprocating engine with an electromagnetically driven light Displacer, which can also be a heat exchanger, characterized in that for driving of the displacer (4) outside the cylinder (5) at least one coil (6) for generating one or several magnetic fields are attached, which are magnetizable through the thin cylinder wall Act on parts of the displacer (4). 2. Hot gas reciprocating engine according to claim 1 with a preferably vertical cylinder, characterized in that the light displacer (4) consists of a thin-walled at its hot end, cylinder made of magnetically influenceable material, which becomes stronger towards its cold end exists, with a certain accumulation of material in the part that leads to the hot end of the Cylinder"; (5) adjacent position of the displacer is held in the core of the magnetic field. 3. hot gas reciprocating engine according to claim 1 and 2, characterized in that one with current pulses acted upon coil (6) is provided outside the cylinder (5) and the displacer (4) is equipped with ferromagnetic parts. 4. hot gas reciprocating engine according to claim 1 and 2, characterized in that one with current pulses acted upon coil (6) is provided outside the cylinder (5) and the displacer (4) Short-circuit conductor (64) carries. 5. hot gas reciprocating engine according to claim 1 to 4, characterized in that the circuit or circuits for generating vl.i magnetic fields for Displacement movement can be switched on and off by a speed-adjustable timer. 6. hot gas reciprocating engine according to claim 1 to 5, characterized in that a plurality of arranged outside the cylinder (5) individual Coils (55, 56, 57) are provided for generating a traveling electromagnetic field. 7. hot gas reciprocating engine according to claim 1 to 6, characterized in that means are provided for pulse reversal. 4S 8. hot gas reciprocating engine according to claim 1 to 7, characterized in that permanent magnets (74) are arranged on at least one of the facing end faces of the displacer (4) and the working piston (3) which are located in a cylinder. 9. hot gas reciprocating engine according to claim 1 to 6, characterized in that for the delivery of the Work for a longer movement of the displacer (4) a spring (82) is provided. 10. Hot gas reciprocating engine according to claim 1 to 9. characterized in that the light displacer (4) consists of a heat exchanger (9) contains light, highly thermally conductive material of high heat capacity, whose working gas eo through the coaxial bore (11) a high-profile, has steep swirl-generating internal thread (12). 11. Hot gas piston engine according to claim 1 to 10, characterized in that damping means for damping or braking the movement of the displacer (4) are provided in the end positions. 12. hot gas reciprocating engine according to claim 1 to 11, characterized in that the permanent magnets (74) are designed as damping means in the form of rubber-elastic magnets. 13. Hot gas reciprocating engine according to claim 1 to 11, characterized in that as damping means a cylinder-piston combination (76, 78 or 77, 79) at least on one end face of the displacer (4) and / or working piston (3) is 14. Hot gas reciprocating engine according to claim 1 to 13, characterized in that to achieve a complete mass balancing without the usual mass balancing means by simultaneous opposing, electromagnetically or electrodynamically induced movement of two displacers two hot gas reciprocating engines are coaxially assembled.