(19)
(11)EP 0 984 163 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
26.10.2005 Bulletin 2005/43

(21)Application number: 99630063.8

(22)Date of filing:  13.08.1999
(51)International Patent Classification (IPC)7F04B 39/02

(54)

Siphon prevention in a compressor lubrication system

Mittel zur Verhinderung eines Siphoneffekts in einem Kompressorschmiersystem

Dispositif empêchant le siphonnage dans un système de lubrification d'un compresseur


(84)Designated Contracting States:
DE FR GB IT

(30)Priority: 03.09.1998 US 146854

(43)Date of publication of application:
08.03.2000 Bulletin 2000/10

(73)Proprietor: CARRIER CORPORATION
Syracuse, New York 13221 (US)

(72)Inventors:
  • Flanigan, Paul J.
    Cicero, New York 13039 (US)
  • Johns, Curtis E.
    Fayetteville, New York 13066 (US)

(74)Representative: Hughes, Andrea Michelle et al
Frank B. Dehn & Co., European Patent Attorneys, 179 Queen Victoria Street
London EC4V 4EL
London EC4V 4EL (GB)


(56)References cited: : 
FR-A- 2 204 234
US-A- 3 688 140
  
  • PATENT ABSTRACTS OF JAPAN vol. 1997, no. 05, 30 May 1997 (1997-05-30) & JP 09 014154 A (SHIMADZU CORP), 14 January 1997 (1997-01-14)
  • PATENT ABSTRACTS OF JAPAN vol. 008, no. 207 (M-327), 21 September 1984 (1984-09-21) & JP 59 093976 A (SEIKO SEIKI KK), 30 May 1984 (1984-05-30)
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description


[0001] Positive displacement compressors include structure for circulating lubricant to parts requiring lubrication. Commonly the lubricant is pumped to the structure requiring lubrication and subsequently drains by gravity to the oil sump. FR-A-2204234 discloses a compressor for a refrigerating machine. Claim 1 is characterised over this disclosure. JP-A-09014154 discloses a check value between a shaft seal housing and a low pressure chamber. In open drive systems the shaft extends through the housing with the oil in the shaft seal cavity coacting with the shaft seal to provide a fluid seal. In the case of refrigerant compressors, refrigerant is present in the oil due to an affinity between oil and refrigerant. Accordingly, if the seal is compromised by the draining of oil from the shaft seal cavity or due to dilution of the oil due to condensing refrigerant, refrigerant may leak through the seal into the atmosphere.

[0002] A check valve is placed in the oil distribution path downstream of the shaft seal cavity. When the compressor is stopped, the oil in the shaft seal cavity upstream of the check valve acts as a column of trapped fluid, much as a soda straw filled with liquid with the top opening sealed by a finger. Accordingly, the column of trapped fluid tends to remain in place. Additionally, a second check valve may be located upstream of the shaft seal cavity to prevent oil from draining from the shaft seal cavity. Thus, most, if not all, of the trapped lubricant remains in place in the shaft seal cavity on shut down and serves to seal the shaft seal.

[0003] It is an object of this invention to prevent oil from siphoning and/or draining out of the shaft seal cavity of a compressor.

[0004] It is another object of this invention to maintain the shaft seal of an open drive compressor. These objects and others as will become apparent hereinafter, are accomplished by the present invention.

[0005] Basically, oil is trapped, upon compressor shut down, in the shaft seal cavity portion of the oil distribution system by a check valve located downstream of the shaft seal cavity. Additionally, a second check valve may be located in the oil distribution system upstream of the shaft seal cavity.

Figure 1 is a partially sectioned view of an open drive reciprocating compressor employing the present invention;

Figure 2 is a partially cutaway and partially sectioned view of a portion of the Figure 1 structure;

Figure 3 is an enlarged sectional view of a first valve illustrated in Figures 1 and 2; and

Figure 4 is an enlarged sectional view of a second valve illustrated in Figures 1 and 2.



[0006] In Figures 1 and 2, the numeral 10 generally designates an open drive reciprocating compressor that relies on oil flooding of the shaft seal cavity 34 to maintain a seal. As is conventional, compressor 10 includes a crankcase 12, one or more cylinder heads 14, and a bottom cover 16. Crankcase or casing 12 is divided into an oil sump 36 containing gaseous refrigerant with liquid oil 37 located therein, and suction plenum 38. The discharge plenum is located in cylinder heads 14. Because compressor 10 is an open drive compressor, a mounting flange 18 is suitably secured to crankcase 12 and serves to permit connecting compressor 10 to a diesel engine, or the like (not illustrated). Crankshaft 20 is operatively connected to the diesel engine, or the like, via key 21 and drives oil pump 22 and pistons 24. A series of interconnecting bores extend through crankshaft 20 and feed radial distribution passages of which only bore 20-1 and radial passage 20-2 are illustrated in Figure 2.

[0007] Crankshaft 20 is supported by bearings 30 and 31 which are axially separated to provide an annular chamber 32 which is supplied with oil via radial passage 20-2 and forms part of the oil distribution path. A series of interconnecting bores 12-1, 12-2 and 12-3 formed in crankcase 12 define a fluid path between annular chamber 32 and shaft seal cavity 34. Bore 12-4 connects the upper portion of shaft seal cavity 34 with oil sump 36. Valve 50 is located in bore 12-2 and valve 70 is located in bore 12-4. Shaft seal 40 is located in shaft seal cavity 34 in a surrounding engagement with crankshaft 20 and includes spring 42 which biases carbon ring 44 into sealing engagement with cover plate 26.

[0008] Referring specifically to Figure 3, valve 50 is a spring biased ball check valve. Spring 52 normally biases ball element 51 onto its seat blocking flow through valve 50 and therefore through bore 12-2 in which valve 50 is located. A shoulder in bore 12-2 serves to properly locate valve 50 in bore 12-2 with valve housing or cage 54 coacting with bore 12-2 and the shoulder to provide a tight fit such that all flow must pass through valve 50 in passing through bore 12-2.

[0009] Referring specifically to Figure 4, valve 70 is also a spring biased ball check valve. Spring 72 normally biases ball element 71 onto its seat blocking flow through valve 70 and therefore through bore 12-4 in which valve 70 is located. One, or more, shoulders in bore 12-4 serve to properly locate valve 70 in bore 12-4 with valve housing or cage 74 coacting with bore 12-4 and the shoulders to provide a tight fit such that all flow must pass through valve 70 in passing through bore 12-4.

[0010] In operation, the diesel or the like (not illustrated) drives crankshaft 20 through key 21 causing crankshaft 20 to rotate. Rotation of crankshaft 20 causes the reciprocation of pistons 24 as well as the driving of oil pump 22. Oil pump 22 draws oil 37 from oil sump 36 and delivers the oil under pressure to a series of interconnecting bores extending through crankshaft which feed radial distribution passages. Bore 20-1 is in fluid communication with the oil pump 22 through the interconnecting bores in crankshaft 20 such that pressurized oil supplied by oil pump 22 serially passes through bore 20-1, radial passage 20-2, annular chamber 32, bores 12-1, 12-2 and 12-3, shaft seal cavity 34, and bore 12-4 back into oil sump 36. The oil distribution path just described is generally conventional. The present invention adds valve 70 which is located in bore 12-4 and, optionally, valve 50 which is located in bore 12-3. Valves 50 and 70 each have a spring bias on the order of 2.7 kg (six pounds) tending to bias them closed.

[0011] Because oil pump 22 is a positive displacement pump, the oil readily flows past check valve 50, if present, into shaft seal cavity 34 which remains essentially filled with oil according to the teachings of the present invention. Oil flows from shaft seal cavity 34, through bore 12-4 past check valve 70 to oil sump 36. When the compressor 10 is stopped, check valve 70 will close when the pressure differential across valve 70 cannot overcome the spring bias acting thereon. With valve 70 closed, the portion of bore 12-4 upstream of valve 70, shaft seal cavity 34, bore 12-3 and at least the portion of bore 12-2 downstream of valve 50, if present, and otherwise all of bore 12-2, will constitute a column of trapped fluid. Gaseous refrigerant may separate from the oil where the oil and refrigerant are miscible but the gaseous refrigerant would collect at the top of shaft seal cavity 34. If check valve 50 is present and there is a pressure build up greater than the spring bias pressure due to the gaseous refrigerant, valve 70 could open thereby relieving the pressure. When the pressure is relieved, valve 70 will close to maintain the column of trapped fluid.

[0012] The primary concern is to keep sufficient oil in shaft seal cavity 34 to provide a fluid seal and thereby prevent the leakage of gaseous refrigerant. Check valve 50 is not necessary, but traps the downstream oil in the event that valve 70 leaks or is otherwise ineffective to create a column of trapped fluid, including shaft seal cavity 34, upon shut down.

[0013] Although a preferred embodiment of the present invention has been illustrated and described, other changes will occur to those skilled in the art. For example, although a reciprocating compressor has been described, the present invention is applicable to other positive displacement open drive compressors such as screw compressors. It is therefore intended that the scope of the present invention is to be limited only by the scope of the appended claims.


Claims

1. An open drive compressor (10) having a casing (12), an oil sump (36), a shaft seal cavity (34), a shaft (20) extending through said seal cavity and said casing, a shaft seal (40) in said seal cavity providing a seal where said shaft extends through said casing, an oil distribution means (20-1; 20-2) for supplying oil from said sump to a path including a passage (12-1; 12-2; 12-3) for supplying oil to said seal cavity and a passage (12-4) for delivering oil from said seal cavity back to said sump, characterised in that the open drive compressor further comprises:
   a check valve (70) coacting with said passage (12-4) for delivering oil from said cavity to only permit flow from said cavity into said passage (12-4) for delivering oil while preventing reverse flow by causing a column of fluid to be trapped when the compressor is stopped.
 
2. The compressor of claim 1 wherein said passage for delivering oil from said seal cavity begins at an upper portion of said seal cavity.
 
3. The compressor of claim 1 wherein when said check valve coacting with said passage for delivering oil is closed said check valve coacting with said passage for delivering oil acts to trap oil in said passage for delivering oil upstream of said check valve coacting with said passage for delivering oil and in said seal cavity whereby an oil seal is maintained in said seal cavity.
 
4. The compressor of claim 1 further including a second check valve (50) located in said passage for supplying oil to said seal cavity.
 


Ansprüche

1. Kompressor (10) offenen Antriebs mit einem Gehäuse (12), einer Ölwanne (36), einem Wellendichtungshohlraum (34), einer Welle (20), die sich durch den Dichtungshohlraum und das Gehäuse erstreckt, einer Wellendichtung (40) in dem Dichtungshohlraum, die eine Dichtung schafft, wobei die Welle sich durch das Gehäuse erstreckt, einer Ölverteilungseinrichtung (20-1; 202) zum Zuführen von Öl von der Wanne zu einem Pfad der einen Durchgang (121; 12-2; 12-3) zum Zuführen von Öl zu dem Dichtungshohlraum und einen Durchgang (12-4) zum Liefern von Öl von dem Dichtungshohlraum zurück zu der Wanne aufweist.
dadurch gekennzeichnet, dass der Kompressor offenen Antriebs ferner aufweist:

ein Rückschlagventil (70), das mit dem Durchgang (124) zum Liefern von Öl von dem Hohlraum zusammenwirkt, um nur eine Strömung von dem Hohlraum in den Durchgang (12-4) zum Liefern von Öl zu erlauben, wohingegen eine umgekehrte Strömung durch Bewirken einer Säule von einzuschließendem Fluid, wenn der Kompressor angehalten ist, vermieden wird.


 
2. Kompressor nach Anspruch 1, wobei der Durchgang zum Liefern von Öl von dem Dichtungshohlraum an einem oberen Bereich des Dichtungshohlraums beginnt.
 
3. Kompressor nach Anspruch 1, wobei, wenn das Rückschlagventil, das mit dem Durchgang zum Liefern von Öl zusammenwirkt, geschlossen ist, das Rückschlagventil, das mit dem Durchgang zum Liefern von Öl zusammenwirkt, dahingehend wirkt, Öl in dem Durchgang zum Liefern von Öl stromaufwärts des Rückschlagventils, das mit dem Durchgang zum Liefern von Öl zusammenwirkt, und in den Dichtungshohlraum einzuschließen, wodurch eine Öldichtung in dem Dichtungshohlraum aufrechterhalten wird.
 
4. Kompressor nach Anspruch 1, ferner aufweisend ein zweites Rückschlagventil (50), das sich in dem Durchgang zum Zuführen von Öl zu dem Dichtungshohlraum befindet.
 


Revendications

1. Compresseur à entraînement externe (10) comprenant un carter (12), un carter d'huile (36), une cavité de joint d'étanchéité (34) d'arbre, un arbre (20) s'étendant à travers ladite cavité de joint d'étanchéité et ledit carter, un joint d'étanchéité (40) d'arbre dans ladite cavité de joint d'étanchéité établissant une étanchéité où ledit arbre s'étend à travers ledit carter, un moyen de distribution d'huile (20-1 ; 20-2) pour envoyer l'huile dudit carter jusqu'à une voie comprenant un passage (12-1 ; 12-2 ; 12-3) pour envoyer l'huile à ladite cavité de joint d'étanchéité et un passage (12-4) pour délivrer l'huile de ladite cavité de joint d'étanchéité à nouveau vers ledit carter, caractérisé en ce que le compresseur à entraînement externe comprend en outre :

un clapet de non retour (70) coagissant avec ledit passage (12-4) pour délivrer l'huile à partir de ladite cavité afin de permettre uniquement l'écoulement à partir de ladite cavité vers et dans ledit passage (12-4) pour délivrer l'huile tout en empêchant l'écoulement inverse, en provoquant le blocage d'une colonne de fluide lorsque le compresseur est arrêté.


 
2. Compresseur selon la revendication 1, dans lequel ledit passage pour délivrer l'huile à partir de ladite cavité commence au niveau d'une partie supérieure de ladite cavité de joint d'étanchéité.
 
3. Compresseur selon la revendication 1, dans lequel, lorsque ledit clapet de non-retour coagissant avec ledit passage pour délivrer l'huile est fermé, ledit clapet de non-retour coagissant avec ledit passage pour délivrer l'huile sert à bloquer l'huile dans ledit passage pour délivrer l'huile en amont dudit clapet de non retour coagissant avec ledit passage pour délivrer l'huile et dans ladite cavité de joint d'étanchéité moyennant quoi une étanchéité d'huile est maintenue dans ladite cavité de joint d'étanchéité.
 
4. Compresseur selon la revendication 1 comprenant en outre un second clapet de non-retour (50) situé dans ledit passage transportant l'huile vers ladite cavité de joint d'étanchéité.
 




Drawing