US 3807904 A
A substantially closed cylinder containing a compressible fluid, such as air, and a free piston for reciprocation within the cylinder, and a number of elongated passageways, each having an end opening into the cylinder and an opposite closed end. The passageways are heated along their lengths. The fin-shaped open end portions and the cylinder wall are cooled. Piston reciprocation is affected by the force of heated expanding gas moving from the closed ends of the passageways to drive the piston in one direction as the gas cools in the region between the piston end and the cooled open ends of the passageways. The piston compresses the gas at the opposite piston face, which gas in turn drives the piston back after the force of the compressed gas exceeds the force of the cooling gas to regularly repeat such cycle.
Description (OCR text may contain errors)
United States Patent Schuman Apr. 30, 1974  OSCILLATING PISTON APPARATUS 3,353,349 11/1967 Percival .1. 60/24  Inventor: Mark Schuman, 101 0 $1., N.W., 5333 53 Washmgtom 20024 3,583,155 6/1971 Schuman 60/24  Filed: Feb. 18, 1972 Primary Examiner-William L. Freeh  Appl' Assistant Examiner-Gregory P. LaPointe Related US. Application Data Attorney, Agent, or Firm-Lowe, King and Price  Continuation-impart of Ser. No. 121,371, March 5, v
1971, abandoned. 57 ABSTRACT [52 us. c1. 417/207 A Substantially closed Cylinder containing a compress- 51 1m. 01. F04b 19/24 ible fluid, Such as air, and a free Piston for reciproca-  Field of Search 417/339, 340, 207; 62/501, hon Within the Cylinder, and a number of elongated 62/6; '60/24 passageways, each having an end opening into the cylinder and an opposite closed end. The passageways 5 References Cited are heated along their lengths. The tin-shaped open UNUED STATFS PATFN-m end portions and the cylinder wall are cooled. Piston reciprocation is affected by the force of heated ex- 51 panding gas moving from the closed ends of the pas- 3678686 7/l972 g z Son 6O/24 sageways to drive the piston in one direction as the gas 3688512 9/1972 pm2121iiIIIIIIIIIIIIIIIIIIIIIIIIIIIIQ 60/24 cools ih the regioh between the Piston ehh and the 310871438 4/1963 Ciesielski 417/207 cooled open ends of the passageways. The piston com- 3,604,82l 9/1971 Martini 60/24 Presses the gas at the pp Piston face, which gas 3,248,870 5/1966 M0rgenroth.... 60/24 in turn drives the piston back after the force of the 3,579,980 5/1971 Kelly .1 60/24 compressed gas exceeds the force of the cooling gas to 3,400,281 9/1968 Malik 60/24 r gularly repeat such cycle, 3,508,393 4/l970 Kelly 60/24 3,080,706 3/1963 Flynn et a! 60/24 36 Claims, 18 Drawing Figures 5 if 2:2 g 74F/9 '\23 a 1 x g f f /5 f j 35 3 1/ A) E 2" 30 a 7 4 36 Mimi-11m 30 m4 SHEET 1 BF 3 FIG? FIG-6 PATENTEUAPRaO 1914 'l-IIIIII \LIIIII:
OSCILLATING PISTON APPARATUS RELATIONSHIP TO CO-PENDING APPLICATION The present application is a continuation-in-part of my co-pending application entitled Oscillating Piston Apparatus," filed Mar. 5, 1971, Ser. No. 121,371, now abandoned.
BACKGROUND OF THE INVENTION The apparatus herein relates to an oscillating piston and cylinder construction which may be used as a pump, such as is described in my US. Pat. No. 3,489,335 granted Jan. 13, 1970 or as a gas analyzer mechanism such as is disclosed in my US. Pat. No. 3,516,745 granted June 23, 1970 or as part of an engine such as is described in my application, Ser. No. 861,256 filed Sept. 26, 1969, now US. Pat. No. 3,583,155, or other devices which utilize thermal energy for power. The apparatus herein is a simplification of and in some directions an improvement of the equipment described in the foregoing patents and applications.
More specifically, the present invention provides some preferred forms of heat transfer surfaces for driving a moving part, e.g., a piston, whereby the heat transfer surfaces are in structures that are relatively efficient and compact. Means are also provided for eliminating some or all of the valves and other pieces of mechanism which were utilized in the abovementioned equipment for restricting fluid flow into a heating chamber and for positioning the center of piston oscillation.
SUMMARY OF THE INVENTION the passageways. A compressible fluid, such as air, is.
forced by the piston face into and through the passageways. The fluid is heated in the passageways and is returned back to the drive chamber to drive the piston in one direction. Simultaneously, the piston compresses the fluid at its opposite face and the compression of fluid in this opposite chamber of the cylinder in which the piston oscillatescauses the piston to rebound or return. Fluid entering the drive chamber during the oscillation cycle is simultaneously cooled to assist in driving the piston in the other direction to thereby regularly repeat the cycle of piston and gas movement.
By using long passageways, heated near one end and cooled near their openings into the drive chamber for providing a difference in temperature between the passageways and the drive chamber, thermopneumatic energy is thereby provided to sustain the natural resonance or oscillation of the piston between the gaseous compression springs at opposite faces of the piston, without the need for additional valving and other mechanical controls. A sealing action of the piston against side walls of the cylinders separates the gaseous com- These and other objects and advantages of this invention will become apparent upon reading the following description, of which the attached drawings form a part.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, elevational, cross-sectional view of the oscillating piston apparatus;
FIG. 2 is a cross-sectional view taken in the direction of arrows 2--2 of FIG. 1;
FIG. 3 is a top or plan view of the piston taken in the direction of arrows 3-3 of FIG. 1;
FIGS. 4-ll, inclusive, show successive positions of the piston during one cycle;
FIG. 12 is an elevational, schematic, cross-sectional view of a modification;
FIGS. 13-17 each illustrate schematic, sectional views of different modifications; and
FIG. 18 is a cross-sectional view of a novelty device utilizing the principles of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIGS. l-3, the oscillating piston apparatus 10 is formed of a closed cylinder 11 containing a free piston 12. The piston has an upper drive face 13 formed with integral, wedge-shaped fins 14. The opposite piston face 15 forms a compression face. Free piston 12 can be considered as having an integral form that has substantially the same cross sectional dimensions and working area throughout its length.
The piston 12 divides the cylinder into an upper; drive, cooling chamber portion 16 and a lower, compression chamber portion 17 which are normally separated from each other by a seal formed between the side walls of cylinder 11 and piston 12. The upper and lower faces of piston 12 can be considered as moving walls of variable volume chambers having fixed wallsv defined by the upper and lower portions of cylinder 11.
' sageways 19, having closed upper ends and lower ends 20 which open into the upper chamber 16 with flared or outwardly wedge-shaped openings to provide greater surface area for cooling. The lower ends 20 correspond in shape to the wedge-shaped fins 14 on the piston 12, to form mating variable geometry cooling passageways. Alternatively, the upper drive face 13 of the piston may be flat and the lower ends 20 of the passageways 19 not flared or wedge-shaped. The passageway lower ends 20 variably exposed by the fins 14 of piston 12 serve as passageway means for cooling heated gas flowing into drive chamber 16.
The upper or closed ends of the passageways 19 are heated by means of a suitable, independent heating mechanism, such as a heating tube 21 for carrying a heated fluid through exterior pipes 22 from a suitable external heater 23. The heating mechanism may be varied and its specific construction forms no part of the invention herein. A lower heating tube 21a may also be included to supply heat some distance below the upper ends of the passageways.
The lower end portions or open ends 20 of passageways 19 are cooled by cooling tube 24, connected by exterior pipes 25 to an externalcooling device 26. Another cooling tube 24a, at thebottom of the flared ends 3 20, may also be included for better cooling. Also a third cooling tube 24b, arranged in the cylinder wall, may be used to cool the cylinder wall surface in the region traversed and variably exposed by the upper drive face 13 of the piston. The form of the cooling device is not part of the invention and may be varied. The object here is to provide one or more heated passageways opening into a cooled chamber containing the piston face, such that the drive chamber has one or more variably exposed cooled passageways. The cooled and heated passageways are formed of a heat conductive material so layer may also be used, forming a somewhat laminated structure. Instead of being straight and arranged in parallel, the fins and passageways may be arranged in other configurations, e.g., the passageways and fins may be circular and arranged in concentric rings. The passageways may, in the alternative, be outside of the cylinder and enter the drive chamber via a port in the side wall of the cylinder.
The upper chamber 16 is connected to the lower cylinder chamber 17, around the piston, by a shunt pipe 28 containing an upper, normally closed valve 29 and a lower, normally closed valve 30, in turn connected to a gas or air inlet 31.
Valves 29 and 30 are made of a conventional wafer, ball, or similar type of pressure closing valve, of the type which is essentially sealed when closed. However, the valves are generally formed so that they do not tightly close at relatively low pressure differential but permit some leakage through them. Leakage through valves 29 and 30 decreases substantially to zero as the differential pressure across each valve increases.
The valves 29 and 30 permit a small upward flow of gas around the piston. When the piston moves up, some gas may leak through the valve 29 to pipe 31. When piston 12 is near the top of its stroke, a small amount of gas enters into the lower chamber 17 due to the valve 30 opening. On the piston downstroke, valve 30 closes whereas gas may enter through valve 29. Due' to the weight of the piston, there'is a little less gas, and a little higher compression ratio, below the piston than. above it. Thus, gas tends to flow upwardly around the piston, and is replaced by a netintake of gas through valve 30 and a net leakage through valve 29. If piston 12 drifts too low, the higher compression ratio below its lower face causes upward movement of the piston, whereby more gas is drawn through valve 30.
To start the reciprocation or oscillation of piston 12, a starting mechanism is necessary. This is schematically illustrated as starter 32, including an external cylinder 33 connected by a pipe 34 into the lower chamber 17 of the main cylinder 11. A piston 35 connected to a piston rod 36, which is moved back and forth (left to right and vice versa as illustrated) by a suitable drive mechanism (not shown) to draw gas through valve 30 into the cylinder 33 and to move gas from the cylinder 33 into the chamber 17 and vice versa to force the piston 12 to move up and down. Once the piston 12 begins mov? ing due to the full operation of the heating device 23 and cooling device 26, the starter is deactivated and positioned close to chamber 17, i.e., at the extreme left,
as viewed in FIG. 1. Usually a single cycle of the piston 35 is sufficient to initiate oscillation.
The oscillation of piston 12 at a particular frequency is determined by a number of factors, including: the inertia or mass of piston 12 and the effect of pneumatic springs formed by the gases compressed by the upper and lower faces of piston 12 while the piston is oscillating. The means for sustaining oscillation includes these factors and further includes: the thermal lag properties of the passageway means, i.e., the time or portion of an oscillating cycle of piston 12 for the maximum and minimum gas temperatures to occur after maximum and minimum compression of the gas in the chamber formed by the passageways and the upper face of piston 12; the amount of heating of gas in passageways 19; the amount of gas cooling in drive chamber 16. It is to be noted that the net flow of cool fluid (fluid colder than the temperature of the hot walls of the passageways 19) that flows or is induced to flow into passageways 19, by the upper face of piston 12, while the pis ton is approaching the passageways, is primarily and directly responsive to pressure variations in this fluid. Further, the pressure variations in the fluid being compressed into passageways 19 is primarily and directly responsive to the changes in the volume of the chamber defined by the upper face of piston 12 and the passageways 19, which changes in volume are caused by the moving chamber wall comprised of the upper face of piston 12.
OPERATION FIGS. 4-11, inclusive, show successive steps in one cycle of movement of the piston 12. Starting with FIG; 4, the piston is shown in its bottom, dead center postion. At bottom dead center, the gas below the piston in the compression chamber (see arrows) pushes the piston upwardly with greater force than is exerted against the upper face of the piston by the expanded, cooling gas in the drive chamber.
FIG. 5 shows the piston moving upwardly under the rebound of the compressed gas in the compression chamber and driving the still cooling gas upwardly into the passageways 19.
FIG. 6 shows the piston in the top dead center position, wherein the pressure of the gas below piston 12 is less than the pressure of the gas above the piston and the gas above the piston is being heated and beginning to return downwardly from the upper closed ends of the passageways l9.
FIG. 7 shows the gas, while still being heated in the I passageways l9 expanding from the passageways into the upper, drive chamber to force piston 12 downwardly with the piston compressing the gas below it. in response to the expanding gas above the piston. The expanding gas above piston 12 is simultaneously being cooled at the lower or outlet ends of passageways 19.
In FIG. 9, piston 12 is about one-half way down, and the force of the gas being compressed beneath the piston is increasing while the force of the gas above the piston is decreasing due to the increased volume of the drive chamber and the decreased volume in the lower chamber, as well as the cooling of the gas in the drive chamber.
FIG. 10 shows the piston about three-quarters of the way down with the pressure of the compressed gas below the piston now exceeding the pressure of the cooling gas above the piston so that the speed of the piston decreases.
FIG. 11 shows piston 12 at its bottom position again,
with the compressed gas below the piston now pushing the piston upwardly against the decreased pressure of 5 the cooling gas above the piston; at this time the pressure above piston 12 is considerably less than the pressure below the piston. Thereafter, the cycle repeats with the piston rapidly oscillating or reciprocating up and down during the repetition of each cycle.
MODIFICATION FIG. 12
FIG. 12 shows a modification wherein the cylinder head 18a is arranged to one side of the top of cylinder 11a and opens into the top of the cylinder through a nozzle like opening 40. The piston 12a may have a smooth or flat top. The fins may be omitted whenever significant power or amplitude of oscillation is not required. The cylinder wall is cooled by cooling tube 24b. The operation and construction is otherwise the same as that described above in connection with FIG. 1. By locating the passageways 190 off to one side of the cylinder, a single set of passageways can be used to synchronously drive more than one piston (see FIG. 14, below). Also, without the fins, the cylinder is clear for use as a variable volume optical chamber gas analyzer by providing the necessary transparent windows in the cylinder either above or below the piston as is described in my prior US. Pat. No. 3,516,745 of June 9, 1970.
MODIFICATION FIG. 13
FIG. 13 shows a construction having a pair of side cylinder heads 18b, 180, each having heating tubes 21 and 21b, as described above. The cylinder heads open through nozzle-like openings 41, into the cylinder 11b,
above and below the piston 12b. The pistonhas upper and lower fins 42 which mesh with fixed cooling fins 43 having cooling pipes 24c. Thus, the piston 12b is positively driven in both directions so that the opposite faces of the piston can be considered as opposed moving walls of a pair of chambers, which walls have a relative phase displacement of 180.
FIG. 13 also shows check valves 29 and 30 polarized to pass air into the chambers above and below piston 12b for positioning the center of piston oscillation. Adjustable, spring biased, flow limiter valve 29a passes an adjustable amount of air to a load (not shown) only when the pressure in the upper cylinder chamber is greater than load pressure by a small amount determined by the position of spring 290. Check valve 29b keeps air from returning from the load. Check valves 29a and 29b can control the pumping power supplied to a load so that piston 12b is not stalled.
MODIFICATION FIG. 14
FIG. 14 shows another modification wherein the cylinder head 18d, which has the same configuration as those shown in FIGS. 12 and 13, has a fluid flow path into the center of the cylinder 116 through nozzle-like opening 45. A pair of pistons 12c, 12d, each having fins 46 on their inner faces, mesh with spaced apart central cooling fins 47-48, having integral cooling pipes 24d. The two pistons are synchronized to move in opposite directions at all times. That is, pistons 12c and 12d are driven apart by the cooling gas located between them, and rebound towards each other by the gas which they compress at the opposite ends of the cylinder. Synchronizing oscillation of the two pistons in this manner can essentially eliminate vibration of the device. More than two pistons can also be synchronized in this manner. Also an additional set of cooling fins in, and heated passageways opening into, each compression chamber, can be added for additional power. The facing faces of pistons 12c and 12d can thereby be considered as synchronized moving walls of a variable volume chamber. The chamber walls move toward each other to compress gas fed into passageways of cylinder head 18d and move away from each other to expand the chamber volume in response to heated gas being ejected from the passageways.
MODIFICATION FIG. 15
FIG. 15 illustrates a modification which is similar to that shown in FIG. 1 above, except that an additional piston l2e is added at the upper end and passageways 19 are not closed at one end. Thus, the cylinder lid is elongated upwardly, as are the passageways 19. The cooling tubes 24 and 24a and the heating tubes 21 and 21a are duplicated and a second insulating or thermal barrier 27a is provided. The upper piston 12s is provided with fins, as in FIG. 1, to mesh with the flared upper ends of the passageways 19. The operation is the same as that described above in connection with FIG. 1, except for the driving of two pistons l2-l2e, instead of the one piston as illustrated in connection with FIG. 1. Alternatively, the stationary and moving fins may be omitted but the drive, chamber walls would nevertheless be cooled. Gases flowing in the upper and lower portions of passageways 19 in response to oscillation of pistons 12 and l2e have a tendency to remain separate from each other even though there is no mechanical obstruction across the passageways. I
MODIFICATION FIG. 16
FIG. 16 illustrates an oscillating piston apparatus 50 including a cylinder lle which contains a single piston 12f, having lower face fins meshing with fixed cooling fins 51. Fins 51 include cooling tubes 52 similar to those described above in connection with FIGS. 13 and- 14. In FIG. 16', head 18c, which is the same as the heads described above in connection with FIGS. l2, l3 and 14, is offset to one side and opens into the cylinder on the side of the cooling fins 51 opposite the piston 12f.
For purposes of positioning the piston 12f, without using valves, vertical grooves 53 are formed in the center portion of the cylinder lle, that is, in the wall of the cylinder. Grooves 53 are by-pass passageways around a portion of the cylinder, which passageways have a fluid flow impedance that is substantially the same to fluid flow in both directions through the passageways. Thus, as the piston moves up and down, the leakage of gas, above and below the piston through the grooves 53, tends to maintain center. of piston oscillation near the center of grooves 53. If, for example, the center of piston oscillation drifts below the center of the grooves 53, more gas leaks downwardly around piston 12f through the grooves 53 while the piston is in the upper portion of its stroke, than leaks upwardly during the bottom portion of its stroke. There is, thereby, a net flow of gas downwardly to raise the center of piston oscillation upwardly.
MODIFICATION FIG. 17
FIG. 17 illustrates apparatus 60 which is identical to that described above in connection with FIG. 16, except that instead of the centering grooves, U-shaped by-pass tubes 61 are formed in the wall of the cylinder for purposes of keeping the center of piston oscillation near or at the center or mid-point of the Ushaped bypass tubes 61. In FIGS. 13, 14, 16 and 17 the heated passageways may alternatively be connected to the drive chamber(s) via a port(s) in the cylinder side wall between the piston and the fixed cooling fins.
MODIFICATION FIG. 18
Reference is now made to FIG. 18 wherein there is illustrated a novelty device or a physics demonstration device adapted to be powered by heat from a convenient source, such as a lamp of the incadescent type. A pair of arcuate, heated passageways, 71 is located in a partially transparent housing 72 having a shape adapted to mate with an incadescent light bulb globe (not shown). The globe supports housing 72 with the aid of metal clip or holding strap 73 that is fixedly mounted on housing 72 and is adapted to be frictionally connected to the globe. Heating of passageways 71 by heat from the lamp can be augmented by providing the housing 72 with radiation absorbing substances, e.g., colored glass. It is to be understood that a single heated passageway may provide sufficient heating to operate the device.
assageways 71, as well as passageways 19, are relatively long and have considerable breadth, but are relatively narrow in width to provide optimum oscillation of gases therein. If housing 72 and passageways 71 are formed of a relatively weak material, e.g., glass, spacing between walls of the passageways is preferably maintained by spacers 74, that are sufficiently small to have only a slight effect on fluid flow in the passageways.
One end of each of passageways 71 is connected in fluid flow relationship to one end of hollow tube 75, that is downwardly depending from housing 72. The other end of tube 75 is connected in fluid flow relationship with transparent cylinder 76 that contains free piston 77. Cylinder 76 can be maintained securely in situ by spring clip 80 that is adapted to be secured to a suitable support, such as a lamp pole that carries the bulb for supporting housing 72. Gas in cylinder 76 is cooled by air'from the surrounding environment, without resort to cooling by cooling coils. To center piston 77, cylinder 76 includes a number of longitudinal grooves 78, centrally located on its interior side wall.
To initiate oscillation of piston 77, the lower end of cylinder 76 is in fluid flow relationship with starter 78 that includes a rubber or plastic bellows 79 having an upper interior wall bonded to the exterior, lower. wall of cylinder 76. Leaf springs 81 catch the folds or lower end face of bellows 79 to maintain the bellows in a compressed state after the bellows has been compressed by an operator. Prior to compression of the be]- lows the lower face of piston 77 bears against the uppermost fold of bellows 79. In certain instances, it is desirable to space the uppermost bellows fold from the lower edge of cylinder 76 to provide a leaky cylinder during starting, whereby air can get below the lower edge of cylinder 76 and establish a better rebound chamber.
In each of the described embodiments, by using the ideal gas law it can be shown that for a given low compression ratio (less than 2:1), the pneumatic power supplied by the heating and cooling means to the piston to sustain piston oscillation is approximately proportional to the amplitude or amount of temperature variation of the gas during the cycle and to the sine of the phase angle of thermal lag introduced primarily by the passageways, i.e., the phase lag of the variation in the average temperature of gas in the chamber with respect to the instantaneous compression ratio. The instantaneous compression ratio can be defined as the ratio of the maximum chamber volume to the instantaneous chamber volume. As illustrated, the length and breadth of each passageway typically are each substantially greater than the passageway width, which may be substantially constant throughout the length and breadth of the passageways. The passageway width is chosen according to the desired frequency of piston operation to be sufficiently narrow and uniform to heat or cool substantially all of the gas in the passageway sufficiently to provide an adequate amplitude of temperature variation. Heating is provided by passageways l9 and cooling by passageways between teeth 14 of piston 12 and by the cylinder wall portion traversed by the piston face.
The amplitude of the variation in average gas temperature during the cycle is determined by the amount of gas which is heated and cooled during the cycle and also by the amount of heating and cooling of this gas.
The passageways are preferably sufficiently narrow to allow heating or cooling of the gas emerging from the passageways throughout substantially all of the cross section of the passageways, whereby there is heat ing or cooling of gas near the center of the passageways, as well as at the walls of the passageways. The passageway width must, however, be wide enough to readily admit sufficient quantities of gas for heating or cooling of the gas in the passageways 19. The passageway width must also be wide enough to provide an adequate angle of thermal lag such that gas is being heated and fed from the thermal lag heater to the piston as the piston is moving away from the heated passageway, and gas is being cooled in the thermal lag cooling chamber (drive chamber) as the piston moves toward the heated passageways, to maintain the piston in oscillation. Thus, a compromise width is generally chosen at any given frequency of operation to maximize the produce of the amplitude of the temperature variation and the sine of the thermal lag angle, so as to increase power and efficiency. Because of the thermal lag requirement, a heat exchanger of this invention typically has a passageway width greater than that of heat exchangers employed in Stirling cycle engines operating at the same frequency.
The breadth and length of a passageway are generally each made larger than the width in order to increase the volume and decrease the fluid drag of the passageway. Thereby, the amount of gas that can be heated or cooled by the passageways is increased, with a minimum increase in surface area and viscous drag. The resulting passageway structure is relatively compact and provides good heating and cooling paths through the solid material forming the passageway walls. Thereby, external heating and cooling of the passageways is made more efficient.
The passageways thus have a characteristic thermal time constant for heating or cooling fluid. The time constant is primarily determined by the average width of the passageways, and secondarily by other factors such as length, and breadth, smoothness, properties of thermal lag heating chamber and an optimum thermal lag cooling chamber.
Because of the thermal lag requirement, it is desired that heating of gas predominate over cooling for a period of time after maximum compression. Correspondingly, it is desired that the net cooling of gas near minimum compression continue for a period of time after minimum compression.
It should be understood that almost any compressible fluid, such as a liquid and its vapor, may be used as the working fluid of this device. However, the thermal lag device of this invention, by itself, is not expected to be as efficient an energy converter as some existing heat engines.
It should also be understood that the center of oscillation of all the pistons illustrated in all the embodi ments herein can be positioned either by check valves, similar to the techniques shown in FIGS. 1 and 13, or by passageway means bypassing a portion of the cylinder wall, as illustrated in FIGS. 16 and 17. For example, in each of FIGS. 14 and 15, the pistons could be positioned by means of three inlet check valves or by means of two by-pass passageways or grooves. In addition, the check valve arrangement illustrated in FIG. 13 for pumping gas can be adapted to any of the embodiments illustrated herein. Pumping power can thus be drawn from any and all chambers of the devices illustrated by appropriately connecting the check valves to the chambers.
While there have been described and illustrated several specific embodiments of the invention, it will be clear that variations in the details of the embodiments vide a thermal time constant that causes cycling of the wall temperature at substantially the same frequency as the piston oscillates.
The device of FIG. 18 can be modified in numerous ways, such as by providing an upwardly extending hollow tube to connect the heated passageways with the cylinder containing the free piston. It is also possible to eliminate clip 73 by forming the passageways in a pair of interconnected sections, each adapted to fit on opposite sides of a lamp globe and dimensioned to be slightly smaller than the globe so as to be frictionally held on the globe with the aid of a fluid conduit connecting the two sections together.
The device described herein may also be used as a cooling device, e.g., for cooling a typical engine valve. Thus, the valve head would contain the heated passageways and the cooled valve stem would contain the oscillating piston. Oscillation of the piston and a gas or fluid within the sealed valve would cool the valve head and valve seat by transferring heat to the valve stem and valve guide and thence to a water jacket or other conventional means for cooling a valve stem.
1. A naturally resonant oscillating device comprising a chamber maintained in a substantially closed condition during at least a portion of the oscillation cycle, means for sustaining oscillation of at least one wall portion of the chamber, an independent heat source for heating fluid passageway means formed in the chamber, means for inducing a flow of cool fluid into said passageway means, said passageway means being designed according to the frequency of oscillation to readily admit said cool fluid and to heat substantially all of said admitted fluid so as to heat fluid in the passageway means as the oscillating portion moves in a direction to increase the volume of the chamber and to eject compressible fluid from the passageway means as the oscillating portion moves in a direction to increase the volume of the chamber, said means for sustaining oscillation including: inertia of a member including the oscillating portion, spring action of fluid compressed by the oscillating portion, said heat source and said flow inducing means; wherein the net flow of fluid induced into the passageway means while the volume of the chamber .is decreasing is primarily and directly responsive to pressure variations of the fluid in the chamber resulting primarily and directly from changes in the chamber volume caused by the oscillating portion.
2. The device of claim 1 wherein the oscillating portion comprises a pair of pistons positioned for synchronous oscillation along a common axis.
3. The device of claim I wherein the oscillating wall portion is a drive face of a piston oscillating in a cylinder.
4. The device of claim 3 wherein the piston is a free piston.
5. The device of claim 4 further including a second heated fluid passageway means opening into the piston rebound chamber at the opposite face of the piston for operation similar to the first heated fluid passageway means.
6. The device of claim 4 wherein the free piston is of substantially integral construction.
7. The device of claim 4 wherein the cross-sectional dimensions of the free piston are substantially the same throughout its length.
8. The device of claim 10 wherein the further passageway means includes at least one passageway having a fluid flow impedance which is substantially the same for fluid flow in either direction through the at least one passageway.
9. The device of claim 4 further including valve means for positioning the center of oscillation of the piston.
10. The device of claim 4 further including further passageway means by-passing a portion of the cylinder for positioning the center of oscillation of the piston near the mid-point of the by-passed portion.
11. The device of claim 4 wherein the passageway means has a shape adapted to mate with an electric bulb which provides heat for heating the passageway means.
12. The device of claim 11 wherein the passageway means includes a substance for absorbing radiant energy from the bulb.
13. The device of claim 1 wherein the fluid passageway means contains at least one elongated passageway having an average length substantially greater than its average width.
14. The device of claim 1 wherein the fluid passage-' way means contains at least one elongated passageway having an averagelbreadth substantially greater than its average width.
15. The device of claim 14 wherein the crosssectional dimensions of the passageway are substantially uniform throughout most of the passageway length.
16. The device of claim 1 wherein the means for inducing a flow of cool fluid includes independent means for cooling fluid induced into said passageway means.
17. The device of claim 16 wherein the means for inducing a flow of cool fluid includes independent means for cooling the chamber walls proximate to the piston.
18. The device of claim 17 wherein the chamber includes walls shaped to form at least one cooling fln, said at least one fin being proximate the oscillating portion.
19. The device of claim 18 further includinganother at least one cooling fin carried by the oscillating portion and shaped to mesh with the at least one cooling fin proximate the oscillating portion.
20. The device of claim 1 wherein the fluid passageway means contains at least one elongated passageway having an average length, an average breadth and an average width, said average length and breadth both being substantially treater than the average width of the passageway.
21. The device of claim 1 wherein the fluid passageway means contains a plurality of elongated passageways.
22. The device of claim 1 wherein the fluid passageway means contains a plurality of elongated passageways having an average length, average breadth and average width, the average length and average breadth of the passageways each being substantially greaterthan the average width of the passageways.
23. The device of claim 1 wherein the passageway means is designed to provide a substantially maximum value for the product of the amount of variation inthe average temperature of fluid in the chamber and the sine of the difference in oscillatory phase ainglc between the temperature variation and the instantaneous geometrical compression ratio of the chamber.
24. The device of claim 1 further including valve means for supplying energy to a load.
25. The device of claim 1 wherein the volume of the heated fluid passageway means is substantially constant during the oscillatory cycle.
26. A naturally resonant oscillating device comprising a chamber maintained in a substantially closed condition during at least a portion of the oscillation cycle, means for sustaining oscillation of at least one wall portion of the chamber, an independent heat source for heating fluid passageway means formed in the chamber, means for inducing a flow of cool fluid into said passageway means, said passageway means being de signed according to the frequency of oscillation to readily admit said cool fluid and to heat substantially all of said admitted fluid so as to eject heated compressible fluid from the passageway means as the oscillating portion moves in the same general direction as the ejected fluid and to heat fluid in the passageway means as the oscillating portion moves in the same general direction as the ejected fluid, said means for sustaining oscillation including: inertia of a memberincluding the oscillating portion, spring action of fluid compressed by the oscillating portion, said heat source and said flow inducing means; wherein the net flow of fluid induced into the passageway means while the fluid is being compressed toward the passageway means by the oscillating portion is primarily and directly responsive to pressure variations of the fluid in the chamber resulting primarily and directly from changes in the chamber volume caused by the oscillating portion.
27. The device of claim 26 wherein the heated passageway means includes first and second sets of heated, elongated fluid passageways for respectively ejecting the heated fluid against first and second oscillating wall portions.
28. The device of claim 27 wherein the first and second sets of elongated passageways eject the heated fluid in opposite directions against opposed wall portions.
29. The device of claim 26 wherein the oscillating portion includes first and second walls moving substantially in synchronism with each other.
30. The device of claim 29 wherein the passageway means is responsive to said flow of cool fluid as compressed by the first and second walls simultaneously moving toward each other and ejects the heated fluid as the first and second walls are simultaneously moving away from each other.
31. The device of claim 30 wherein the passageway means is positioned in fluid flow relationship between the first and second walls.
32. The device of claim 30 further including means for providing a fluid flow path for the cool fluid compressed by the first and second walls into the passageway means and for the heated fluid ejected by the passageway means against the first and second walls.
33. The device of claim 30 further including means for providing substantially equidistant flow paths between the passageways means and the snychronized first and second walls 34. An oscillating piston apparatus comprising a cylinder, a free piston in the cylinder, means for sustaining oscillatory motion of the piston in the cylinder, and means for controlling the location of the center of oscillation of the piston in the cylinder, said controlling means including a rebound chamber for reversing the motion of the piston and at least one passageway bypassing a portion of the cylinder and having a fluid flow impedance which is substantially the same to fluid flow in both directions through the at least one passageway wherein said portion of the cylinder is at least partially traversed by the piston.
35. The apparatus of claim 34 wherein the free piston is of substantially integral construction.
36. The apparatus of claim 34 wherein the crosssectional dimensions of the free piston are substantially the same throughout substantially all of its length.
UNITED STATES PATENT OFFICE CE J TTFICATE 0F CORRECTION Patent No. 3,807,904 Dated April 30, 1974 l fl Mark Schuman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
FRONT PAGE  (Inventor's address) change "N.W., to -S.W.-.
IN THE ABSTRACT 2 Line 8, change "affected" to --effected.
IN THE SPECIFICATION:
Column 4, line 54, after "it" insert In Figure 8, piston 12 is about one-quarter of the way down, compressing the gas below it to force the gas downwardly-.
Column 8, line 49, change "produce" to -product-.
Column 11, line 38, change "treater" to --greater-.
Signed and Scaled this first Day of June1976 [sun A ttes t:
RUTH c. msou c. MARSHALL DANN Arresting Officer Commissioner ofParems and Trademarks