DE1601538A1 - Free piston gas generator - Google Patents

Description

DR. MÖLLER-BORG DIPL.-ING. GRALFS DR. MANITZ © R DEUFEL PATENT LAWYERS

January 25, 1968

Our ΖβίΛβη: Al / Be - B 598

Braun-Gampbell Engineering Limited PO Box 1268
Kingston, Ontario
KMTADA

Ifreikobben-ü-asgenerator

The invention relates to Brennkraftmas chinea and more particularly relates to an I free-piston gas generator.

A relatively high proportion of the losses in a piston engine can be attributed to the heat flow from the combustion chamber through the cylinder walls and the piston. In the case of a free-piston gas generator, in which the hot exhaust gases are used to drive a turbine, the heat losses in the combustion chamber are even greater, since this represents an energy loss yr ± - ^ r [ , dor, iverin ex ^v in the exhaust gas remain on a chief; ' in -J.or Jurb-L-ie ausgenuasi; vje ^ i ^ i ·. could =

BATH ORIGINAL

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The aim of the invention is a gas generator in which only little heat is lost from the combustion chamber.

According to the invention, a three-piston gas generator is nit an Ilotor cylinder, which has a cylindrical wall open at the ends, which encloses the combustion chamber, and provided with two opposing pistons, cKe reciprocable in the cylinder are and each have an end wall that is opposite to each other Form piston crown, with at least one of these parts with one lying in the vicinity of the wall Vacuum chamber is provided, which thermally insulates the combustion chamber.

In a preferred embodiment of the invention, each piston is defined by a hollow, cylindrical member formed, which is closed by the piston head and another wall remote from the piston head so that the vacuum chamber is formed therebetween.

The motor cylinder preferably has a cylinder liner which forms the cylinder wall; the Vfdcuuaikammer between, two walls lying radially in the Abs band from each other is formed, which the cylinder liner

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Ei'flnduns is for example in the accompanying drawing and is explained in detail below:

Mg »1 is a longitudinal cross-section through an embodiment of a gas generator according to the invention, the right part of the gas generator to be visited Clarity is omitted.

FIr. 2 is a diagram showing calculated efficiencies of a gas generator according to the invention in comparison with other machines.

Throughout the following description, the same reference numbers are used. With 1 is in the drawing a Preikolben gas generator according to FIG Invention referred to. This gas generator has a rotor cylinder 2, which has a cylindrical wall 3 is provided, which encloses a combustion chamber or a combustion chamber 4-. Inside the cylindrical wall J is reciprocable a pair of opposing pistons, 5 »5 arranged, each with end walls 6.6 are provided, which the piston crown 7 * 7 the piston form. The rotor cylinder 2 and the pistons 5.5 are inside each with sealed vacuum chambers

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öc and 8p, which the cylindrical wall 3 and face the end walls 6,6 and thermally insulate the combustion chamber.

The lio gate cylinder has a sleeve 10, which of course must consist of a high temperature alloy. This sleeve 10 is in the middle between its ends provided with a small opening 11, which the nozzle 12 of a fuel injection device ^ 13 of known design records. The injection device 15 is arranged so that that they fuel in the combustion chamber 4 essentially rlt-im injected when the two pistons meet the inner Enä <; approach their strokes, as it does with a two-stroke machine !! common is. At the height of one of the outer ends of the cylinder liner 10 is a ring of openings or air inlet ducts provided, one of which can be seen at 14-, and that lead to the combustion chamber. The openings are arranged in such a way that they are exposed when the piston 5 on the left of the drawing is the very end of the Has reached Hubes. Compressed air can then be supplied from a pipe 15 enter the combustion chamber. On the other side of the opening 11 than the openings 14 is another one Row of outlet openings or channels, not shown provided by the one on the right side Piston 5 will be exposed as it moves to the outer end of its stroke. The outlet channels are in

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binding with a gas turbine, not shown, the turbine being driven by the hot exhaust gases emerging from the combustion chamber 4.

The chambers or pockets 8c in the engine cylinder are preferably formed in a housing or outer part 16, which is composed of a number of parts, so that two annularly spaced apart v / andungen are formed, which between them the chambers 8c and enclose the cylinder liner 11. In In practice, the outer part is assembled before the sleeve 11 is inserted. The outer part 16 initially has two concentrically arranged cylindrical parts 17 and 18, both of which are provided with an opening into which a Insert 20 for the injection device 13 is welded in. When the insert 20 is in the openings of the cylindrical Parts 17 and 18 are attached by welds 23 and 24, the space between parts 17 and 18, i.e. the chamber 8c, no longer connected to the atmosphere via the openings. As shown in Fig. 1, the left ends of the cylindrical parts 17 and 18 by welds 25 and 26 with axially extending flanges 21 and 22 of the manifold 15 connected, which have corresponding diameters. The opposite Ends of the cylindrical parts 17 and 18 are attached to the outlet manifold 19 in a corresponding manner.

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closed. If the welds 23, 2A and 25 »26 and the corresponding welds at the opposite end or at least the last welds are carried out under vacuum with the aid of the electron beam welding process which is now frequently used, it is possible to close the chamber tic in the evacuated state. Since the vacuum chamber remains hermetically sealed by the welds, a heat flow from the cylindrical part 17 to the cylindrical part 18 is made more difficult. Since the heat is therefore essentially prevented from leaving the cylinder liner 10 through the engine cylinder 2, the temperature within the combustion chamber 4 remains at a higher value, which leads to a higher exhaust gas temperature.

The gas generator is provided at each of its ends with an air compressor 30 and a discard cylinder 31, these means being designed identically at the two ends of the gas generator so that _€ only the left part is shown in the drawing. The discard cylinder 31 has a sleeve 32 which is in the axial direction with the sleeve 10 of the combustion chamber 4-aligned. The bushing 32 lies within an extension 33 of a part 34 which at the same time represents the cylinder head of the compressor 30. The discard cylinder 31 is closed at its outer end by a head 35, which is extended with screws

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is connected, of which only one dai'-qoiiueilt in the drawing is. The head 35 has a threaded hole 37 to which known devices for controlling the Printing in throwback cylinders can be connected. «Vi: - 'c: ien the growths 32 and the extension 33 can Channels 3ß be provided for cooling, so that the! Temperature i can be controlled by a cylinder.

»; (Hie! · Kolbvn; is with an elongated, hollow section

40 provide aeeaen one end of one piece with the S-uiiiiwan-A ■ consists. An inner part 4-1 of the piston, which can be moved back and forth in the cylinder liner 10 of the purging space, has a different diameter-ex al π an outer part 42 in the eückvnu'fzyliii -ier, so that between the ends of the piston 5 a catch lug ^j r 44 is formed. I ^ as the inner tongue

41 3itr, t with a tight fit inside the can 10 and instead of the usual piston rings it is provided with a number of closely spaced Uia retaining grooves 4-5, which represent a labyrinth seal. In the discard cylinder viird the seal between the outside End 42 of the piston 4 and the sleeve 32 in the same way caused by grooves 46.

The outer end 42 of the piston 5 within the. Discard cylinder 31 is; by an end plate 50

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closed with the elongated hollow section 40 of the piston is connected in such a way that a completely completed part is formed. The.endplate 50 is in this way connected to the piston by a weld 51 connected that the chamber within the piston 5 is hermetically sealed. When welding is again like already explained above - an electron beam welding process used, so that the vacuum is maintained within each piston 5 and practically no heat can escape from the combustion chamber 4 · through the piston crowns 7 »7.

In the Ilotoraylinder 2, an annular bearing 55 is provided at each end of the cylinder liner 10 which receives the inner end 41 of the piston 5 such that it can move back and forth. These piston bearings are each held in their position ^{by a ring r} _y L ·. The outer end 4-2 of the piston 5 is similarly guided in an annular bearing 57 which is held in place in the vicinity of the inner end of the discard cylinder liner 32 by a Hing 5ß.

As in 3? Ig. 1, there is the outer layer. End of the Hotorzylinders 2 in reality from one piece with an end part 60 of the compressor 30. This end part 60 is provided with a bore that the outer The end of the cylinder liner 10 receives, and v / eist at a distance mutually lying annular flanges 61 and 62 on,

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which meet with annular flanges 63 and 64, welciie on the other side of the manifold 15 than the Flanges 21 and 22 are located. The flanges 61 and 63 as well 62 and 64 are joined by welds 65 and 66, respectively connected, similar to the above in the electron beam welding process are produced so that an additional vacuum chamber de outside the manifold 15 is produced, which extends the combustion chamber 4 · even further thermally insulated from the environment.

The end part 60 of the air compressor 30> that in the gas generator between the combustion chamber 4 and the discard cylinder 31 is with the cylinder head 34- of the air compressor vex'bunden by a plurality of bolts and nuts, one group of which is shown at 70. Between the '34 cylinder head and end portion 60 is seated with a liner Vl, which defines the compressor cylinder 72, which surrounds the piston 5 concentrically. In the same way will a cooling jacket 73 is held between the parts 34 and 60, which rests on the outer surface of the sleeve 71. Within of the compressor cylinder 72 is seated on the piston 5 piston-ringed compressor piston 74 · like shown - is mounted on the piston 5 in such a way that it moves back and forth with this. The attachment is made in that the Verdiohterkolben between the shoulder 44 and a nut 75 is clamped, the

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on a threaded part 76 of the piston 5 in the line of the Shoulder 44 is screwed on.

The cylinder head 34 is provided on the side of the cylinder 72 with an inlet valve 77, the atmosphere is sucked into the cylinder 72 through the air av.3 when the piston 'j> performs its return movement by the buffer effect. The valve 77 is a one-way valve which closes as soon as the working stroke of d-, s piston begins, ao that the trapped in the compression cylinder 72 through the air piston 74 compresses wii'd. The cylinder head 34 is further provided with a plurality of one-way exhaust valves 78 a; n the end of the cylinder 72, which are arranged around the piston 5. These outlet valves ' / L allow the air sealed in cylinder 72 on the working stroke to flow out into an annular chamber 81. From chamber 81, the air flows through a channel 82 connected to chamber 81 to the collecting line and from there through the openings 14 into the combustion chamber when the piston 5 approaches the outer end of the working stroke, as shown in Ifig. 1 is indicated by the arrows 90. The manifold 15 also receives the air that has been compressed by the compressor that is on the other side of the gas generator. This compressor, which brings the air through a second duct 83 into the collecting

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line leitot, is the compressor explained above λοminen the same.

Even if the; The way in which the pistons 5 are held in the gas generator 1 is of secondary importance, old ν * jch is irrelevant. For example, the described design enables the desired surface of the throwback piston to be selected, which is completely independent of: lolüe -, lurcuuetiser in the furnace. The interpretation UGa iiückwurf '/. Vlin-ierE r.usaiaiuen with the way in cUr the La.tur yj and 5? <ien piston ^l; - füiiren is also viichtig insofar as small Sj) IEIE zv / een the piston and the bushings are made possible, which can be effectively sealed by the labyrinth seals described.

Obviously it is also possible to provide the vacuum chamberii only in the piston 5> 5 or in the I ^- Io gate cylinder 2 and still achieve the advantages of increased efficiency. However, the more perfect the insulation brought about by the vacuum chambers, the better the efficiency of the machine. Even if the invention has been explained in connection with a free piston gas generator, the features of the present invention can also be used in a piston engine operating with a crankshaft. In such machines ü However, the improvement in efficiency is not so important

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substantial as in the case of one working with a turbine Gas generator, since in the latter case the increased efficiency is based on an improved diesel efficiency, which leads to an increase in the compression work, i.e. to a higher mass throughput for a given Input power and leads to an increased exhaust gas temperature, which leads to a reduction in heat losses from the cylinder is based. With a machine working with a crankshaft, there is no thermodynamic advantage drawn from the higher temperature of the exhaust gases when the engine is not interacting with an exhaust gas turbocharger. Another fact that the present invention applies to free piston gas generators as illustrated in FIG are shown, make appear more suitable than for machines with a crankshaft is that in the Free piston machine · the pistons are essentially free of Lateral forces are so that - because on the pistons 5 »5 no external rods are connected - the pistons are ringless with the labyrinth seals described can be. This is particularly important with hot machines.

The design of the piston shown in Fig. 1 can be used for other types of internal combustion engines or for Gas generators can of course be modified. For example, it is not necessary that the

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Vacuum chamber extends over the entire length of the piston. It can be one or it can be several transverse walls closer to the end wall 6 are provided so that a shorter or a number of shorter vacuum chambers within the Pistons are formed in the vicinity of the piston crown.

In order to improve efficiency, the vacuum chambers in the pistons can also be advantageous for the engine in that they reduce the stresses in the piston crown. For example, the mean piston temperatures in a highly charged diesel engine are 250 psiBMEP (17.6 kp / cm ² mean effective pressure when braking) with a boost pressure ratio of 4 and with piston cooling in the range of 4 - 50 to 500 ° 0 the resulting stresses, which are represented by pressure and thermal stresses, are very high. If the flow of heat through the piston through the vacuum chambers is prevented, the general temperature level of the piston crown is close to the mean G-a temperature, which would be about 800 to 1000 ° 0 at a maximum gas temperature of about 2000 ° 0. Since the heat transport through the piston crown is essentially prevented, the thermal stresses are greatly reduced. However, the material for the pistons must obviously be a high-temperature alloy that can withstand the stresses at the increased working temperatures * Ican-n »

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The thermal efficiency of a gas generator is arranged is used with estimated component efficiencies, Yen ti 1- and opening pressure losses and the percentage cylinder heat loss from the following equation:

'.A \ ύ-1 / ύ

(* turb J __,

(1-Hi) +

Ύ-1 / Ύ

Mean

H, = »percentage of total heat loss x = indexed diesel efficiency - Romanian overall efficiency = isentiOpic compressor efficiency

if = pressure loss factor ρ = atmospheric pressure ^p turb

Turbine inlet pressure

The possible winnings can be calculated this way and compared to the usual gas generator arrangements. As a comparison, they are in thirty-three. 2 on ge tx * agen. In The diagram is, as a borderline case, H, equal to Hull is set, and a corrected curve is given, which is generated by a step-by-step calculation of the leakage losses past the labyrinth seal and see the other thermodynamic Corrections was determined.

009882/0462

Vv υ it; Curves are shown around in which show the efficiencies voji ;; white andex'en iiaschiiienax'ten, namely of an au: ". cladeiien ibtor and an orbundriotor, where" in the latter, part of the corrugation -iileistuiig aur Untex * - «t; iüi: unc serves to drive an exhaust gas turbine that drives a compressor for the incoming fragrance. From the slide ^ aia :! £ OLZ clearly shows that with an arrangement according to GUI * L. iiiitiiLiß dex * efficiency of the gas generator he-Lot-lent special: ·; is then raised when higher loading "dxnicke (boo;». px'ossures) are used. a ·: «η of the aiideron Ilaschineii of the gloicuen class.

Line still extensive lüolierung the Bronnraums 4 can be achieved, if one polishes the length of the hexagon lying parts in the combustion chamber or otherwise plated or treated, for example the inner surfaces of the connections that define the vacuum chambers 8c and 8p , OEO that the radiant heat from the combustion chamber back £ eflektiert viird. for example, the inner surface Wa can be polished of the member 40 and the inner surface 50 a OCE end plate 50 ö ^ of the piston 5, so that the \ ohlte heat is reflected back abgestx from the piston head 7 and the heat cannot escape from the surroundings of the combustion chamber In the same way, the inner surfaces 18a of the cylindrical

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Part 18 are also made reflective, so that the radiant heat is returned to the combustion chamber 4- will. Finally, the inner surface 6a in the chamber 8p of each piston 5 and the outer surface 17a of the cylindrical part 17 in the chamber 8c matt and dark be designed so that heat-absorbing surfaces are formed v / ground. In this way, that of the faces 40a, i? 0a and 18a reflected heat more easily from the Chambers 8p and 8c returned to combustion chamber 4.

The embodiment shown and explained is self-evident is only an example and can be modified and changed in many ways without the Is left within the scope of the invention.

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Claims (1)

Claims ^ 1. JJreikobben G-asex'generator with a hot cylinder, the one \ ^ / has open, cylindrical wall at the ends, which enclosing a combustion chamber, and with two opposing pistons which can be reciprocated in the engine cylinder lie and each have an end wall that each other Form opposite piston heads, characterized in that the engine cylinder (2) and / or the Piston (5) with one in the vicinity of the respective, den The combustion chamber delimiting wall (10} 7) lying vacuum chambers (8c, 8p) for thermal insulation of the combustion chamber (4) are provided. 2. gas generator according to claim 1, characterized in that that each piston (5) is represented by a hollow, cylindrical part (40) which extends through the end wall (6) and one in the longitudinal direction of the cylinder at a distance therefrom further wall (50) to form the vacuum chamber (Bp) is closed. 3. Gas generator according to claim 1 or 2, characterized in that that the engine cylinder (2) has a cylinder liner (10), which forms the cylinder liner, and that the vacuum chamber (8c) between two at a distance from each other - and walls lying coaxially to one another (Γ? j 18) is formed, which enclose the cylinder liner, 009882/0452 - is - 4 ·. Gas generator according to claim 3, characterized in that that the inner surface of the outer wall (IS) of the two coaxial walls is designed to be reflective is so that the radiant heat is reflected back to the combustion chamber (4) is, and that the inner wall (1?) dea wall pair a heat-absorbing outer surface for To facilitate the return of heat to the ßj-ennraura. 5. Gas generator according to claim 1, characterized in that that one of the vacuum chambers (8c, 8p) with reflective Surfaces to hinder the heat radiation of the combustion chamber is provided. 6. Gasex'zeuger according to claim 5 »characterized in that that each piston (5) has a vacuum chamber (8p), and that the end wall (6) of each piston in the chamber has a matt, dark, heat-absorbing surface. 7. Gas generator according to one of the preceding claims, characterized in that each piston (5) has a plurality of closely spaced circumferential grooves (4-5) in the vicinity of the piston head (7) to form a labyrinth seal having. 8. It eikolben gas generator according to claim 1, characterized in that the motor cylinder (2) has a cylinder liner ■■: - ■■■., - * BATH 009882/0452 and an outer casing arranged around the liner ClfcO has at least one name contains sealed vacuum chamber (8c), dit, - extends around the Bronnraun (4) around. '}. Gas generator _r according to claim 8 characterized in that DIE two pistons (5?) Each have an inner, in the Z / lindorbüchse reciprocating end (6), and in that the pistons are hollow in the Hähe of the piston head and a have hermetically sealed vacuum chamber (8p) to hinder the flow of heat through the piston. 10. Gas generator according to claim 9 »characterized in that two further cylinders (31) are provided, aligned with the combustion chamber (4), on both sides of the combustion chamber and each form a throw-over cylinder for the pistons (5), whereby the two pistons each have an elongated, hollow, Cylindrical 2-part (40) on v / iron, the end of which is closed and can be moved back and forth in the corresponding throw-over cylinder borders. 11. Gas generator according to claim 10, characterized in that the cylindrical ieil (40) forming the piston (5) consists of one piece with the piston head (7), and that ♦ the end of the The piston is closed by an end plate (50), 009882/0452 which is welded to the cylindrical part and the vacuum chamber (8c) in the hollow cylindrical part between the piston crown and the end wall. 12. Gas generator according to claim 11, characterized in that two ring-shaped compressor cylinders (72) between the combustion chamber (4) and the throwback cylinders (31) are arranged concentrically around the pistons (5), \ md that a piston (74) in each compressor cylinder ), which is connected to the corresponding piston (5) in such a way that it is reciprocated therewith. 13. Gas generator according to claim 12, characterized in that the cylindrical file (4-0) forming the piston (5) for Formation of a surrounding shoulder (44; on the inner and outer Section (41; 42) have different diameters, and that the corresponding compressor piston (74) held between the shoulder and a nut (75) is on a threaded part (76) ües cylindrical part is screwed on at the height of the shoulder. 14. Gas generator according to claim 12 or 13, characterized in that the Ilo tor cylinder liner (10) has an Imfteinlaß (14) for the combustion chamber (4), and that at least one of the compressor he cylinder ev (72) with the air inlet in Has connecting compressed air outlet (78). 009882/0452 15. (Jas generator according to one of claims 10 to 14, characterized characterized in that each piston (5) at the inner and outer ends has a plurality of closely spaced Circumferential grooves (4-5) to form labyrinth seals having. 16. Gas generator according to claim 10, characterized in that at opposite ends of the cylinder liner (10) and in the height of the throwback cylinder (Jl) bearings' (55j 57) are provided, which receive and guide the piston (5) back and forth . 00 9882/0452