US3793836A

US3793836A - Thermodynamic reciprocating machine comprising a compressor

Info

Publication number: US3793836A
Application number: US00246141A
Authority: US
Inventors: J Abrahams
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1971-05-04
Filing date: 1972-04-21
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: NL7106039A; IT954948B; GB1392843A; DE2220454C3; SE370759B; DE2220454B2; NL161233C; CA958546A; FR2135630A1; DE2220454A1; JPS5249098B1; NL161233B; FR2135630B1

Abstract

A thermodynamic reciprocating machine having an integral compressor in which at least one compression element is present within the buffer space and is connected to the pistonlike member which bounds the buffer space or to the associated piston rod, which element can vary the volume of a compression space, at least one piston ring being present as an inlet valve between the cooperating wall parts of the compression element and the compression space, said ring being incorporated in a groove in the wall of the compression element or of the compression space, an open communication being always present between the compression space and the space in the groove behind the piston ring, the outlet valve which communicates with the compression space being accomodated in the wall of the compression space, the outlet being passed to the outside through a wall of the buffer space.

Description

United States Patent Abrahams [4 Feb. 26, 1974 Primary ExaminerEdgar W. Geoghegan Assistant ExaminerH. Burks, Sr.

[75] Inventor: Ja-cobus. Abrahams Attorney, Agent, or Firm-Frank R. Trifari Emmasmgel, Emdhoven, Netherlands [7 3] Assignee: U.S. Phillips Corporation, New

York, NY. [57] ABSTRACT [22] Filed: 1972 A thermodynamic reciprocating machine having an [21] Appl. No.: 246,141 integral compressor in which at least one compression element is present within the buffer space and is connected to the pistonlike member which bounds the [30] Foregn Apphcanon Prlomy Data buffer space or to the associated piston rod, which ele- May 4, 1971 Netherlands 7106039 ment can vary the volume of a compression Space at least one piston ring being present as an inlet valve be- [52] U.S. Cl. 60/521 tween the cooperating wan pans of the compression III. CI. element and h compression p Said g b g [58] Fleld of Search incorporated in a groove i the wall of the p sion element or of the compression space, an open [56] References C'ted communication being always present between the UNITED STATES PATENTS compression space and the space in the groove behind 2,558,495 6/ 1951 Muller et al. 60/24 the pi n ring, the outlet valve which communicates 2,607,190 8/1952 Kohler 60/24 with the compression space being accomodated in the 2,616,243 /1952 n eenen 60/2 wall of the compression space, the outlet being passed 3,550,371 12/1970 Jaspers 60/24 to the Outside through a wall f the b ff space 3,667,348 6/l972 Gregorius 60/24 FOREIGN PATENTS OR APPLICATIONS 5 Claims, 4 Drawing Figures 655,565 7/l95l Great Britain 60/24 21 17 i 17 20 1 20 22 15 7 E i I I l 1 I Q THERMODYNAMIC RECIPROCA'I'ING MACHINE COMPRISING A COMPRESSOR The invention relates to a thermodynamic reciprocating machine comprising a working space in which a medium performs a thermodynamic cycle and the volume of which can be varied by pistons which can reciprocate with a mutual phase difference, one surface of at least one piston influencing the volume of the working space and the other surface influencing the volume of a buffer space in which an average medium pressure prevails which is at least substantially equal to the average medium pressure in the working space, said piston being connected to a driving mechanism via a piston rod passed through a wall of the buffer space, the machine comprising a compressor for forcing medium from the said spaces into a high pressure medium storage container, said compressor comprising an inlet valve which communicates with the buffer space as well as an outlet valve which can be made to communicate-with the storage container via an outlet.

A thermodynamic reciprocating machine of this type is known from the US Pat. No. 3,372,539. In this case the compressor forms part of a power control device. For controlling the power of the machine, the average medium pressure level in the working space of the machine is varied by withdrawing and supplying, respectively, medium from and to, respectively, said space. When medium is withdrawn, said medium is forced into a high pressure storage container by the compressor.

As a result of the presence of the medium-filled buffer space the large pressure forces exerted by the medium in the working space on the piston are compensated for; the rod forces in the driving mechanism are comparatively small so that said driving mechanism may have a comparatively light construction, also a low pressure can prevailin the crankcase, so that the construction of the walls of said case can also be comparatively light.

Thermodynamic reciprocating machines are to be understood to include within the scope of the present invention, hot gas reciprocating engines, cold-gas reciprocating machines and heat pumps. In the working space of such machines, the medium is alternately compressed when it is mainly present in a partial space of the working space, the compression space, then transported to a partial space, the expansion space, via a regenerator; subsequently, when the medium is mainly present in the expansion space, it is expanded and finally transported back to the compression space again via the regenerator, after which the cycle is completed. The compression and expansion spaces have different temperatures during operation. Structurally, such thermodynamic reciprocating machines are to be divided into thermodynamic reciprocating machines of the displacer type (British Pat. No. 1,024,274) and thermodynamic reciprocating machines of the two piston type (British Pat. No. 1,053,896). In thermodynamic reciprocating machines of the displacer type, a piston ensures the alternate compression and expansion of the medium in the working space, while a displacer ensures the transport of the medium from the compression space to the expansion space and vice versa. The displacer may be connected to a driving mechanism, or not be coupled mechanically and be reciprocated as a free displacer by medium pressure forces.

In thermodynamic reciprocating machines of the two-piston type, both a compression piston and an expansion piston are present which in cooperation ensure the desirable compression, the transport and the expansion of the mecium.

In the thermodynamic reciprocating machine known from the US. Pat. No. 3,372,539, the compressor is present separately as a part of the power control. This exhibits a few drawbacks. First of all, as a result of this the assembly of thermodynamic reciprocating machine with power control device is rather bulky. This is a drawback in particular for applications in which the available space is minimum, for example, in cases in which the thermodynamic reciprocating machine isa hot gas engine applied as a power source in vehicles, aircraft, submarines or in cases of cold gas refrigerators used on board, for example, aircraft. Special precautions are necessary for driving the compressor in the case of hot gas engines a separate driving mechanism outside the engine and a special coupling to a shaft of the engine, respectively; in cold gas refrigerators, in which an electric motor is usually accommodated in the crank-case of the engine as a drive, a separate driving mechanism.

Conventional compressors furthermore exhibit the drawback that some leakage of lubricating oil usually occurs from the sump to the working space of the compressor. Said lubricating oil is dragged along by compressed medium as a result of which pollution occurs in the system of ducts, the storage container, and the machine. In particular when oil reaches the regenerator of the machine, this has a disastrous effect on the efficiency of the machine. Finally, the presence of the separator compressor having special driving precautions makes the plant comparatively expensive.

It is the object of the present invention to provide a thermodynamic reciprocating machine in which the above-described drawbacks are mitigated. To achieve this object, the thermodynamic reciprocating machine according to the invention is characterized in that the medium compressor forms an integral part of the machine; at least one compression element is present inside the buffer space and is connected to the piston which bounds the buffer space or to the associated piston rod, and this element can vary the volume of a compression space. At least one piston ring is present as an inlet valve between the cooperating wall parts of the compression element and the compression space. This ring is incorporated in a groove in the wall of the compression element or of the compression space, with an open communication being always present between the compression space and the space in the groove behind the piston ring. The outlet valve which communicates with the compression space is accommodated in the wall of the compression space, the outlet being passed to the outside through a wall of the buffer space.

Since the compressor now forms an integral part of the thermodynamic reciprocating machine, a compact and comparatively cheap assembly is obtained and a source of oil leak to the working medium is avoided. Structurally, all this is simple to provide, and a separate driving mechanism of the compressor is no longer necessary. Since the inlet valve is constructed as a piston ring, the dead space normally inherent in inlet valves is minimum in the present case and a comparatively large compression ratio of the integral compressor is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are cross-sectional views of hot gas engines of the displacer type FIGS. 3 and 4 are cross-sectional views of cold gas refrigerators of the two-piston type..

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference numeral 1 in FIG. 1 denotes a cylinder in which a piston 2 and a displacer 3 can reciprocate with a mutual phase difference. The working face of the piston 2 varies the volume of a working space which consists of two partial spaces, a compression space 4 present between the piston 2 and the displacer 3 and an expansion space 5 the volume of which is varied by the upper working face of the displacer 3. The two spaces communicate with each other via a cooler 6, a regenerator 7 and a heater 8.

The working space is filled with a medium, for example hydrogen or helium, which performs a thermodynamic cycle in the working space. Thermal energy originating from a burner 9 can be supplied to said medium from without. With its lower surface, the piston 2 varies the volume of a buffer space 10 present between the compression space 4 and a crankcase 11. The buffer space 10 is filled with the same medium of the same pressure as that of the working space, so that the pressure forces exerted on an average by the medium in the compression space 4 on the working face of the piston 2 are substantially compensated for by the average pressure forces exerted on the lower face of the piston 2 by the medium in the buffer space 10.

Via the narrow gap 12 between the cylinder 1 and the piston 2, medium can flow from the compression space 4 to the buffer space 10 when the pressure level in the buffer space is reduced. The piston 2 is connected, via a hollow piston rod 14 which is passed through the wall 15 of the buffer space 10 in a gas-tight manner, to a driving mechanism which is not shown and is arranged inside the crankcase 11.

The displacer 3 is also connected to the driving mechanism via a displacer rod 16 which is passed through the piston 2 and the hollow piston rod 14 in a gas-tight manner. Inside buffer space 10 an annular plunger 17 is present as a compression element which is connected to the piston rod 14 via a connection element 18. During the reciprocating movement of the piston rod 14, the annular plunger 17 varies the volume of an annular compression space 19 which in this case is constituted by a recess in the wall 15 of the buffer space 10.

Between the cooperating wall parts of the plunger 17 and the compression space 19 are present two piston rings 20 and 21 which are incorporated in

grooves

22 and 23 in the outer and inner wall, respectively, of the plunger 17 and which serve as inlet valves for the compression space. On their lower sides, the piston rings comprise radially extending grooves 20 and 21, respectively, as a result of which there is always an open communication between the compression space 19 and the spaces in

grooves

22 and 23 behind the piston rings.

This open communication may also be realized differently, for example, by providing the

grooves

22 and 23, instead of the piston rings 20 and 21, on their lower surfaces with radially extending grooves or by providing apertures in the plunger 17 which extend from the spaces in the grooves behind the piston rings to the compression space 19. The compression space 19 comprises an outlet valve 24 which can be made to communicate with a storage container for high pressure medium (not shown) via an outlet 25 which is passed to the outside through the wall of the buffer space.

During operation of the hot-gas engine, the annular plunger 17 moves with the piston rod 14 and the piston 2, respectively. When the plunger moves upwards, when the pressure in the compression space 19 is lower than in the buffer space 10, the sides of the piston rings 20 and 21 comprising radial grooves engage the lower surfaces of the

groove

22 and 23 but together with these form no seals. Medium can be drawn from the buffer space 10 into the compression space 19.

After plunger 17 has passed its uppermost position (top dead center) and moves downwards, the upper sides of the piston rings 20 and 21 engage the upper sides of the

groves

22 and 23, when the pressure in the compression space 19 becomes larger than in the buffer space 10, and a good seal is formed so that the medium present in the compression space 19 cannot flow back to the buffer space 10.

The medium in the compression space 19 is then compressed and leaves said space via outlet valve 24 which opens when the pressure in the compression space 19 exceeds the pressure exerted by the output valve spring 24' and by the medium in the outlet 25.

When the power supplied by the engine is to be reduced, the medium is forced from the compression space 19 via outlet 25 into a high pressure medium storage container. When maintaining a given engine power, the medium forced out of the engine by the plunger 17 can be returned via a return duct directly to the buffer space 19 or the working space (compression space 4).

In FIG. 2 the same reference numerals are used as in FIG. 1 for corresponding components but with suffix a added. In this embodiment, compression space 19a is bounded by piston rod 14a and a housing 30. The volume of compression space 19a is varied by a flange 31 of compression element 2a secured to piston rod 14a. Two

piston rings

32 and 33 are present which again serve as an inlet valve. Piston ring 32 is incorporated in groove 34 in the wall of the flange 31, while piston ring 33 is accommodated in a groove 35 in the wall of the housing 30. The two

piston rings

32 and 33 comprise radially extending grooves on their sides facing the compression space 19, which grooves again ensure that there is always an open communication between the compression space 19 and the space in the

grooves

34 and 35 behind the piston rings 32 and 33, respectively.

A rolling diaphragm 36 is present as a seal between the piston 14a and the displacer rod 16a, said rolling diaphragm separating the working space from the crankcase 11a, while a rolling diaphragm 37 is present between the housing 30 and the pistonrod 14a and separates the buffer space 10a from the crankcase 11a. Medium can flow from the buffer space 10 to the piston 33 via aperture 38 in the wall of the housing 30.

During the upward stroke of the piston rod 14a with a lower pressure in compression space 19a than in buffer space 10, the piston ring 32 engages with its lower side having radial grooves the lower side of the groove 34, while the piston ring 33 engages with its upper side provided with radial grooves the upper surface of groove 35 so that medium can flow freely from the buffer space a via

grooves

34 and 35 and

piston rings

32 and 33, respectively, to the compression space 19a. During the downward stroke of the piston rod 14a, the medium in the compression space 19a is compressed by the flange 31. As soon as the pressure in the compression space 190 is larger than in the buffer space 10a, the piston ring 31 engages with its upper side the upper surface of groove 34 and a good seal is obtained. In the same manner, piston rings 33 engages with its lower side the lower surface of the groove 35 and a good seal is produced in this case also. Medium can no longer flow back to the buffer space 10a and is further compressed until the outlet valve 34 opens.

The cold gas refrigerator shown in FIG. 3 comprises a cylinder 41 in which a compression piston 42 and an expansion piston 43 can reciprocate with a mutual phase difference. Between the two pistons are arranged a cooler 44, a regenerator 45 and a freezer 46 through which medium can flow from a compression space 47 to an expansion space 48 and vice versa. Two

buffer spaces

49 and 50 are present in which an average medium pressure prevails which is equal to the average medium pressure in the working space.

Via a piston rod 51 which is passed to the exterior through wall 52 of the buffer space 50, piston 42 is connected to a driving mechanism not shown. A rolling diaphragm 53 is present as a seal between said wall and the piston rod. The piston 42 comprises on its lower side two plungers having plunger 55. The plungers can vary the volume of two compression spaces 56 within two cylindrical sleeves 57 secured to the wall 52 of the buffer space 50. The two compression spaces 56 communicate with a common duct which communicates with exhaust 60 via outlet valve 59.

Piston rings 62 are incorporated as inlet valves in grooves 61 in the walls of the plungers 54. In this case also, the piston rings on their sides facing the compression spaces type. comprise radially extending grooves. The operation of the integral compressor of the cold gas refrigerator is equal to that of the hot gas engines shown in FIG. 1 and 2, so that further description thereof is not deemed necessary.

In the cold-gas refrigerator shown in FIG. 4 the same reference numerals are used for components corresponding to the refrigerator shown in FIG. 3 but with suffix b.

In a manner analogous to the hot gas engine shown in FIG. 2, the piston rod 51b in the present embodiment comprises a flange 61b which can vary the volume of compression space 62 within the housing 63. In this case also, two

piston rings

64 and 65 are present as inlet valves, piston ring 64 being incorporated in a groove in the wall of the flange 61b and piston ring 65 being accommodated in a groove in the wall of the housing 63.

Piston ring 64 comprises radially extending grooves on its lower side and piston ring 65 comprises said grooves on its upper side. Medium can flow from the buffer space 50b to the piston ring 65 via aperture 66 in the wall of the housing 63. For the rest, the operation of this integral compressor is equal to that shown in F IG. 2, so that description thereof is not deemed necessary.

Of course, all kinds of other embodiments of the integral compressor are possible. At the same time, in the cold-gas refrigerators shown in FIG. 3 and 4, an integral compressor may also be incorporated in the buffer space 49, if desirable.

In the embodiments shown, the integral compressor always draws medium directly from the buffer space. It is of course also possible to cause the compressor to draw medium directly from the working space. This may be effected, for example, by connecting a duct to the inlet side of the compressor, which duct is connected to the working space.

What is claimed is:

1. In a thermodynamic apparatus including within a cylindrical bore of a housing, reciprocally movable c0- axial compression and displacer pistons which define with the bore a variable volume working space, and a variable volume buffer space adjacent one end of the compression piston, said spaces comprising a closed system in which a gas is cyclically compressed and expanded, with the average gas pressure substantially equal in the working and buffer spaces, the improvement in combination therewith of a compressor for forcing gas from said buffer space out of said closed system, comprising a frame part of the housing within the buffer space defining a compression chamber including an scalable outlet, a compression element movable axially within said chamber for varying the volume thereof, the chamber and element having adjacent relatively moving wall surfaces between which is a space operable as an inlet to said chamber, one of said adjacent surfaces having a groove therein, the groove having opposite top and bottom edges relative to said axis of the pistons, a sealing ring situated in said groove and having corresponding top and bottom edges, means for moving said compression element in phase with movement of said compression piston, the seal ring movable between first position with the top edges of the ring and groove in contact in sealing relationship, and second position with the corresponding bottom edges in contact and a gas passage defined therebetween whereby movement to said first position causes said ring to move until said bottom edges contact, and a volume of said chamber is reduced, and gas therein is compressed and forced through said outlet out of said system. i

2. Apparatus according to claim 1 operable with a gas storage container, further comprising means for communicating gas discharged from said compressor outlet to said container.

3. Apparatus according to claim 1 wherein said means for moving said compression piston and compression element compreses a single piston rod, and wherein said compressor chamber and compressor element are annular and coaxial with said rod.

4. Apparatus according to claim 1 wherein said seal ring includes on said bottom edge a radial groove for providing said gas passage.

5. Apparatus according to claim 1 wherein the apparatus is a hot gas engine.

W105 UNITED STATES PATENT OFFICE 56 CERTIFICATE OF CORRECTION i mm 3, '93836 v I Dated Februery 2 1974 Inventor( s)' JACHOBUS HUBERTUS ABRAHAMS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01. 2, line 2 8, delete "Said" and insert --Suc Col. 5, line 3, "10" should be --l0a-- line 20, "34" should be -24- line45, after "spaces" delete "type" and insert Signed ahd sealed this 29th day of October 1974.

(SEAL) Attest: I

McCOY M. GIBSON JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

1. In a thermodynamic apparatus including within a cylindrical bore of a housing, reciprocally movable coaxial compression and displacer pistons which define with the bore a variable volume working space, and a variable volume buffer space adjacent one end of the compression piston, said spaces comprising a closed system in which a gas is cyclically compressed and expanded, with the average gas pressure substantially equal in the working and buffer spaces, the improvement in combination therewith of a compressor for forcing gas from said buffer space out of said closed system, comprising a frame part of the housing within the buffer space defining a compression chamber including an sealable outlet, a compression element movable aXially within said chamber for varying the volume thereof, the chamber and element having adjacent relatively moving wall surfaces between which is a space operable as an inlet to said chamber, one of said adjacent surfaces having a groove therein, the groove having opposite top and bottom edges relative to said axis of the pistons, a sealing ring situated in said groove and having corresponding top and bottom edges, means for moving said compression element in phase with movement of said compression piston, the seal ring movable between first position with the top edges of the ring and groove in contact in sealing relationship, and second position with the corresponding bottom edges in contact and a gas passage defined therebetween whereby movement to said first position causes said ring to move until said bottom edges contact, and a volume of said chamber is reduced, and gas therein is compressed and forced through said outlet out of said system.

5. Apparatus according to claim 1 wherein the apparatus is a hot gas engine.