MOMENTUM ENGINE

Abstract: A free-piston engine in which combustion gas is conducted around a piston (11) via inertial channel (19) for a short time during the expansion stroke. The resulting lowered pressure enables intaking in the final part of this stroke. Pressure from the gas conducted around the piston (11) via inertial channel (19) and ports (25, 26) provide the piston rebounding force and the engine output.

Description: Description Momentum Engine This application is a continuation of application 801,423 filed Nov. 25, 1985, which was a continuation of Serial No. 583.665 filed Feb. 27, 1984. Technical Field This invention relates to cyclic internal combus¬ tion engines and their processes, and particularly engines whose output is gas under pressure such as the free-piston. Background Art Previous similar free piston engines have output gas from their combustion chamber at the end of the expansion stroke and utilizes supercharging to force gas into the combustion chamber against the output pressure in a conventional two-stroke cycle. These engines have also generally required a separate bounce chamber to rebound the piston at the end of the stroke. The need of supercharging and bounce chamber have added significantly to the complexity of these engines. Disclosure of the Invention An object of this invention iε a high efficiency engine. Another object of this invention iε an engine cycle wherein the combustion chamber iε exhausted part-way into the expansion stroke. Another object of this invention is a high com ¬ pression engine which applies only easily managed SUBSTITUTESHEET stresses to its component parts. Another object of this invention is an engine capable of durable operation without conventional oiling or cooling. 5 Another of this invention is an engine readily made from non-metallic materials. Further objects and advantages of this invention will become apparent from a consideration of the drawings and ensuing description. 10 Description of Drawings Fig. 1 is a schematic cross-sectional illustration of a single piston engine of the present invention. Fig. 2 is a pressure-volume-curve of an engine of the present invention. 15 Fig. 3 is a schematic cross-sectional illustration of a dual-piston engine of the present invention. Fig. 4 -is a cross-section view A-A of the channel 39 of Fig. 3. Fig. 5 is a pressure-volume curve of an engine of 20 the present invention. Fig. 6 is a partially sectioned outline view of an embodiment of the present invention. Best Mode for Carrying Out the Invention Referring to FIG.l, the piston 11, which is 25 attached to rod 20, is fitted to the cylindrical casing 12. Starting air jet 14 provides an aerosol of fuel from the fuel jet 15, through the reed check valve 16, and into the combustion chamber 17. Spark plug 18 is fired on the opening of the breaker points 30 23 by the inward travel of the rod head 24. Inertial channel 19 and ports 25 and 26 can also be composed of a slot in the casing 12 when passed over by the piston 11. Such a slot can be spiraled around inside the casing 12 to achieve the desired length. Rings 27 limit leakage of gas across the piston 11. Receiver 21 collects and smooth pressure fluctuations of the gas, which are then delivered by pipe 22 to 5 the turbine 29, whose work output iε from the rotating shaft 30. Starting is accomplished by forcing the rod head 24 inward, driving the piston 11 to compress fuel air mixture in the combustion chamber 17, and opens 10 breake.r 23, firing the spark 18. The high pressure of combustion, C in Fig. 2 causes the piston 11 to move outward and opening the port 25 at D in Fig. 2, where the gas pressure DE causes flow through the inertial channel 19. The work available to cause 15 this high speed flow is the area DGE. This flow once set in motion continues causing a further drop in pressure from E ' to F. The work done in this pumping is the area HEF. Area DGE is greater than area HEF to make up for throttling and flow losses and at high 20 power levels shock losses. At point F, the continued travel of the piston 11 closes port 26 and further expansion FA is carried on by the piston 11 until the pressure is lowered below P-in, opening valves 16, admitting new air. The piston 11 stopε its outward 25 travel when the kinetic energy acquired by the piston 11 in the initial expansion CDEI is used up in traveling against P-out, area EFAJ. The piston 11 then begins the compression stroke driven by the work represented by the area JAB, which then becomes the 30 compression work BIC. Combustion then occurs com¬ pleting the cycle. The volume of the inertial channel 19 is suffi¬ cient that the pumping work HEF can be a achieved by the kinetic energy of the gas mass in this channel's 35 volumn traveling at less than the local speed of STITUTE SHEET sound. The length of the inertial channel 19 is such thatthe time taken to accelerate εmd decelerate the gas column is equal to the time between the opening of port 25 by the piston 11 and the closing of port 526 by the piston 11. The piston speed crossing the ports is determined by the mass of the piston 11 and rod 20 acted on by the expansion work ICDE. To minimize throttling losses, the port 25 should extend along the opening edge of piston 11 as far as possi- 10 ble consistent with a shape having low flow losses. This enables an abrupt valving action, which quickly bring the whole pressure DE to bear, accelerating the gas in the inertial channel. Referring to Fig. 3, ceramic cylindrical casing 31 15 contains the heavy ceramic piston 32 and the light ceramic piston 33. The velocity and stroke of the counter-balancing, oppositely moving pistons are inversely proportionate to their masses. Spring 47, whose force is light when compared to the air 20 pressure forces, maintains the reciprocating pistons in the same lengthwise position in the casing 31. Intake port with non-return reed valve 50 and conduit 40 for valves 41, 42, and 44 pass through the casing 31. For starting, air from tank 45 through valve 41 25 enters the combustion chamber 49 side of the pistons driving the pistons apart, which engage pawls 34 and 35. Valve 42 then releases air from between pistons. With valve 40 closed, valves 43 then pressurizes receivers 36 and 37 through pipe 46. Pipe 46, which 30keeps the pressure in the receivers 36 and 37 equal, can also be equipped to utilize pressure fluctuation to apply a relatively small pressure differential between receivers 36 and 37 moving the combustion position in the casing 31. Pawls 34 and 35 then 35release pistons which accelerate inward. Electrical fuel pumping means not shown receives a signal from sensor 48 measuring the inwardness of piston 32 to determine the point for fuel pumping through the injector 38. Channel 39 permits flow bypassing the piston 33. Non-return valve 44 enables recharging 5 of the tank 45. Fig. 4 shows the cross-section of the channel 39 which is adapted to fast valving action by the piston 33. 10 Referring to Fig. 5, arrow 53 represents the starting pressurization of the receivers 36 and 37. The initial inward movement of the pistons which compresεes 55 air between the pistons continues till the channel 39 opens, when air flows around piston 15 33 through the channel 39. The channel 39 is open for flow when the volume between pistons is between the dotted lines 61. This flow is represented by curve 56, which inertially continues below P-out the pressure of receiver 37 utilizing the kinetic energy 20 of the flow. This spill 56 of gas from the com¬ bustion chamber 49 serves to stabilize the quantity of gas compresεed for combustion. The momentum of the pistons continues the compression 57, fuel is injected at 58 from the injector 38, co busion fur- 25 ther increasing the pressure. The pressure due to compression and combustion stops and turn the pistons into the initial expansion 59 which continues until the channel 39 opens and blowdown-scavenge 60 results. The outward momentum of the piston con- 30 tinues 61. Piston 32 uncovers the intake 34 at 63 and air is drawn in when the pressure between the pistons goes below P-in 62. This intaking continues until the outward momentum of the piεtons is exhausted 54; and the whole cycle repeats. Output 35 of gas at pressure P-out iε available from valve 40 to such as a turbine. SUBSTITUT Fig. 6 shows a spiral slot 73 in the casing 74, which when covered by the piston 32, forms a channel to permit flow around the piston 33. The spiraling about the casing of a channel lessens flow losses due to turning gas out and back into the casing while achieving the desired length. To reduce side- force on the piston, a second channel 180 degrees around the casing from the first can be employed to balance pressure on the piston. Similarly, groves circling the outside of the pistons will equalize pressure side-forces. The channel can also be annularly extended completely around the casing. While the above description contains many specificities, these should not be construed as limitations on the scope of the present invention but exemplifications of details of construction and arrangement of parts. Many other variations are possible. SUBSTITUTE SHEET

Claims: Claims 1. Apparatus generating pressurized gas from the combustion of fuel comprising: a piston fitted to a casing, said piston being able to accelerate when acted on by gas pressure; a chamber to one side of said piston providing for the combustion of fuel; a first port in said casing being opened by the travel of said piston; a second port in said casing being closed by the further travel of said piston; and a channel communicating said first port to said second port so that the closure of said second port by said piston prevents flow in said channel. 2. Apparatus as in Claim 1 further including a receiver communicating with the opposite side of said piston from said chamber and collecting gas released by said first port. 3. Apparatus as claimed in Claim 1 where the cannel communicating said first port to said second port is an inertial channel proportioned to pump substantial gas from said chamber. 4. Apparatus as claimed in Claim 1 where said first port is shaped to abruptly initiate the release of gas from said chamber. 5. Apparatus as claimed in Claim 4 where the channel communicating said first port to said second port is an inertial channel proportioned to pump substantial gas from said chamber. 6. Apparatus as claimed in Claim 1 where said chan¬ nel is formed between said piston and said casing. 7. Apparatus as claimed in Claim 2 where the forces acting on said piston are the forces in said chamber on one side of said piston and the substantially constant pressure of the said receiver on the other side of said piston. 8. An apparatus for effecting a thermodynamic cycle comprising: 5 a piston fitted to a casing and moving in said casing in response to gas pressure difference between sides of said piston; a chamber located to one side of said piston pro¬ viding for the containment of gas under pressure; 10 means to release gas from the chamber side of said piston after an initial expansion of gas by said piston; means to utilize energy of said released gas to pump gas from said chamber; 15 a further expansion by said piston of gas remaining in said chamber after said pumping of said chamber; and means to return said piston at one extreme of said piston's movement in said casing. 9. Apparatus as claimed in Claim 8 where the means 20 to return said piston receives gas from said releas¬ ing means. 10. Apparatus as claimed in Claim 8 where the means for releasing gas comprises an inertial channel proportioned to pump substantial gas from the chamber 25 side of said piston. 11. Apparatus as claimed in Claim 10 where the said means to release gas is shaped to abruptly initiate said release of gas. 12. Apparatus as claimed in Claim 11 where the means 30 to return said piston receives gas from inertial channel. 13. Apparatus as claimed in Claim 8 where said gas pressure difference moving said piston is the said chamber's pressure on one side of said piston and a 35 substantially constant pressure on the other side of said piston. 14. Apparatus as claimed in Claim 8 where said release of gas is stopped by the covering of a port in said casing by said piston. 15. Apparatus as claimed in Claim 8 where the output is gas under pressure from said releasing means. 16. The method of executing a thermodynamic cycle comprising: the drawing in of air for compressing; the compression of said drawn in air; means increasing the pressure of said co presεed air; an initial expansion of said pressured compressed air; a further expansion by a gas momentum generating process through an unthrottled opening; a process utilizing said generated gas momentum to pump air from a lower to a higher pressure; and a final piston expansion drawing in air for the next compression. 17. Apparatus generating pressurized gas from the combustion of fuel comprising; a casing having two piston disposed to sides of a chamber in said casing; said casing also haveing an inlet passage for said chamber; an initial expansion of gas by the pistons from their inward position following combustion in said chamber; a bypass passage opened by one of said pistons after said initial expansion; said bypass passage being closed by the further travel of one of said pistons; a further expansion of gas after said passage is closed; and means to rebound said pistons toward their said inward position. 18. Apparatus as claimed in Claim 17 where said inlet passage has a non-return valve. 19. Apparatus as claimed in Claim 1- wherein said inlet passage is blocked by one of said pistons when said pistons are in their inward position. 5 20. Apparatus as claimed in Claim 18 where said inlet passage has a non-return valve. 21. Apparatus as claimed in Claim 20 where said inlet is unblocked during a substantial part of the expan¬ sion stroke. 1022. Apparatus as claimed in claim Claim 17 where part of the gas in said chamber is released through said passage during the compression stroke. 23. Apparatus as claimed in Claim 17 where said released gas is said rebound means. 1524. Apparatus as claimed in Claim 17 where the said bypass passage is proportioned to inertially pump substantial gas from said chamber. 25. Apparatus as claimed in Claim 17 where said two pistons are of substantially different masses. 2026. Apparatus as claimed in Claim 17 where the forces controlling the movement of one of said pistons is said chamber's pressure on one side and a substan¬ tially constant pressure on the other. 27. Apparatus as claimed in Claim 8 where said 25 passage is formed between said casing and one of said pistons. 28. Apparatus as claimed in Claim 8 where said passage is in the shape of a spiral about said casing. 3029. In a free-piston engine having a casing fitting two pistonε for the compression and expansion of gas; a port in said casing for the passage of gas; in relationship to each other, one of said two 35 pistons is light while the other is heavy; the light piston's mass is selected to provide a εtroke greater than said light pisto 'ε length in response to the pressures of said compression and expansion of gas, thereby providing substantial com¬ pression and expansion; 5 while the heavy piston's mass is selected to provide a stroke less than said heavy piston's length in response to the pressures of said compression and expansion of gas, thereby providing substantial coverage of said port in said casing. 1030. Apparatus as claimed in Claim 29 further provid¬ ing a passage bypaεεing around one said of said pistons. 31. Apparatus as claimed in Claim 28 where the forces controlling the movement of one of said piston is the 15 pressure of said compresεion and expanεion on one side and a subεtantially constant pressure on the other. SUBSTITUTE SHEET

Inventors: HAMMETT ROBERT B, HAMMETT, ROBERT, B.
Applicants: HAMMETT ROBERT B, HAMMETT, ROBERT, B.
Application year: 1988
Main classification: F02B71
IPC codes: F02B71, F02B75