EP0094457B1 - Safety arrangement for a vacuum pump - Google Patents

Safety arrangement for a vacuum pump Download PDF

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Publication number
EP0094457B1
EP0094457B1 EP82302456A EP82302456A EP0094457B1 EP 0094457 B1 EP0094457 B1 EP 0094457B1 EP 82302456 A EP82302456 A EP 82302456A EP 82302456 A EP82302456 A EP 82302456A EP 0094457 B1 EP0094457 B1 EP 0094457B1
Authority
EP
European Patent Office
Prior art keywords
exhauster
valve
housing
thermostat
chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82302456A
Other languages
German (de)
French (fr)
Other versions
EP0094457A1 (en
Inventor
Lothar Peter Schmitz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gardner Denver UK Ltd
Original Assignee
Drum Engineering Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Drum Engineering Co Ltd filed Critical Drum Engineering Co Ltd
Priority to DE8282302456T priority Critical patent/DE3269580D1/en
Priority to EP82302456A priority patent/EP0094457B1/en
Priority to AT82302456T priority patent/ATE18459T1/en
Publication of EP0094457A1 publication Critical patent/EP0094457A1/en
Application granted granted Critical
Publication of EP0094457B1 publication Critical patent/EP0094457B1/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/28—Safety arrangements; Monitoring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/10—Other safety measures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2270/00—Control; Monitoring or safety arrangements
    • F04C2270/19—Temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2270/00—Control; Monitoring or safety arrangements
    • F04C2270/70—Safety, emergency conditions or requirements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2270/00—Control
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/303—Temperature
    • F05B2270/3032—Temperature excessive temperatures, e.g. caused by overheating

Definitions

  • the present invention is concerned with vacuum pumps or exhausters.
  • a problem with existing vacuum pumps is that of overheating in certain circumstances which can lead to early rotor bearing failure or, if not prevented, to complete seizure and failure of the rotor bearings.
  • the problem arises, for example, when the exhauster is pulling too high a vacuum for the cooling capabilities provided.
  • the power consumption of an exhauster at constant speed remains substantially constant over the whole vacuum range. However, at peak vacuum no air enters or leaves the exhauster and substantially all the power consumed in rotating the exhauster rotor is converted into heat.
  • the particular vacuum level at which overheating occurs depends on a number of factors such as (a) the rotor speed - cooling problems tend to be greater with higher speed machines; (b) the size of the exhauster - smaller machines run cooler than larger ones; (c) the ambient temperature - if this rises the problem can be aggravated; (d) the presence or otherwise of large cooling fans, large ribs and correct design of internal porting can affect the ability of a given machine to tolerate internally generated abnormal temperatures; (e) the presence of worn exhauster blades; dirt - e.g. road dirt, building up to reduce cooling efficiency.
  • an exhauster having a rotor eccentrically mounted within a chamber in a stationary housing to draw in air from a suction region and deliver this air through an outlet port, and a valve which selectively admits the entry of atmospheric air to said suction region, characterised in that the valve is controlled by a temperature responsive control means which is arranged to open the valve from its normally closed position when the operating temperature of the exhauster exceeds a predetermined value, thereby temporarily reducing the vacuum pulled by the exhauster, and automatically to close said valve again when the operating temperature of the exhauster falls below said predetermined value, whereby the exhauster returns to pulling full vacuum.
  • valve takes the form of a snifter valve controlled by a thermostat located in a chamber in the exhauster housing.
  • the exhauster illustrated in the drawings is basically of conventional design and will not be described in detail herein. It includes a rotor 10 which is mounted for rotation within a stationary housing 12 by means of a central shaft 14 journalled in bearings 16, 18. The rotor is eccentrically mounted relative to a cylindrical chamber 20 defined within the housing 12 whereby radial vanes 22, radially displaceable in respective slots 24, draw in air from a suction region of the chamber and deliver this air through an outlet port. The shaft is driven by means of a moving belt at 26.
  • the exhauster is conventional.
  • the exhauster includes a valve arrangement indicated generally at 28.
  • the valve 28 includes an annular body member 30 which is screwed into a tapped bore 32 in the exhauster housing.
  • the outer end of the body member 30 defines a frusto-conical valve seat 34 which is adapted to co-operate with a frusto-conical closure member 36 carried by one end of a pin 38.
  • the other end of the pin 38 engages a thermostat unit 40 contained in a chamber 42 of the exhauster housing whereby, when the temperature at the thermostat unit 40 exceeds a pre-determined temperature, the pin is displaced to the left as viewed in Fig.
  • the valve thus provides a means of limiting the temperature variations for the exhauster without losing the capability of pulling full rated vacuum.
  • valve configuration and position illustrated any valve may be used which admits air to the suction side in dependence upon a predetermined temperature in the exhauster being exceeded.

Abstract

A vacuum pump or exhauster has a rotor (10) eccentrically journalled within a cylindrical chamber (20). In order to prevent overheating, the exhauster housing (12) contains a valve arrangement (28) having a closure member (36) which is coupled to a thermostat (40) such that, above a predetermined temperature, the closure member is lifted from its associated valve seat (34) to thereby admit atmospheric air to the suction side of the exhauster via a housing cavity (46).

Description

  • The present invention is concerned with vacuum pumps or exhausters.
  • A problem with existing vacuum pumps (described hereinafter as exhausters) is that of overheating in certain circumstances which can lead to early rotor bearing failure or, if not prevented, to complete seizure and failure of the rotor bearings. The problem arises, for example, when the exhauster is pulling too high a vacuum for the cooling capabilities provided. The power consumption of an exhauster at constant speed remains substantially constant over the whole vacuum range. However, at peak vacuum no air enters or leaves the exhauster and substantially all the power consumed in rotating the exhauster rotor is converted into heat.
  • The particular vacuum level at which overheating occurs depends on a number of factors such as (a) the rotor speed - cooling problems tend to be greater with higher speed machines; (b) the size of the exhauster - smaller machines run cooler than larger ones; (c) the ambient temperature - if this rises the problem can be aggravated; (d) the presence or otherwise of large cooling fans, large ribs and correct design of internal porting can affect the ability of a given machine to tolerate internally generated abnormal temperatures; (e) the presence of worn exhauster blades; dirt - e.g. road dirt, building up to reduce cooling efficiency.
  • One way of countering this problem would be. to provide a sophisticated forced-air cooling system but this would considerably increase the overall cost of the machine. Large two-stage . exhausters are often water-cooled but are not suitable for many applications, such as on road tankers, being rather large, heavy and expensive.
  • It is known to incorporate into vacuum pumps a simple spring-loaded valve which is adapted to limit at all times the vacuum pulled by the pump to a level well below the maximum of which the pump is capable. The disadvantage of such an arrangement is that full vacuum can never be pulled so that operating times are increased. This arrangement is therefore unpopular with users.
  • It is an object of the present invention to provide an exhauster in which the problem of overheating at high vacuum levels is obviated.
  • In accordance with a first aspect of the present invention, there is provided an exhauster having a rotor eccentrically mounted within a chamber in a stationary housing to draw in air from a suction region and deliver this air through an outlet port, and a valve which selectively admits the entry of atmospheric air to said suction region, characterised in that the valve is controlled by a temperature responsive control means which is arranged to open the valve from its normally closed position when the operating temperature of the exhauster exceeds a predetermined value, thereby temporarily reducing the vacuum pulled by the exhauster, and automatically to close said valve again when the operating temperature of the exhauster falls below said predetermined value, whereby the exhauster returns to pulling full vacuum.
  • Advantageously the valve takes the form of a snifter valve controlled by a thermostat located in a chamber in the exhauster housing.
  • The invention is described further hereinafter by way of example, with reference to the accompanying drawings, in which:-
    • Fig. 1 is a longitudinal section through an exhauster in accordance with the present invention; and
    • Fig. 2 is a partial transverse section to an enlarged scale showing the snifter valve in the exhauster of Fig. 1.
  • The exhauster illustrated in the drawings is basically of conventional design and will not be described in detail herein. It includes a rotor 10 which is mounted for rotation within a stationary housing 12 by means of a central shaft 14 journalled in bearings 16, 18. The rotor is eccentrically mounted relative to a cylindrical chamber 20 defined within the housing 12 whereby radial vanes 22, radially displaceable in respective slots 24, draw in air from a suction region of the chamber and deliver this air through an outlet port. The shaft is driven by means of a moving belt at 26. Thus far, the exhauster is conventional.
  • In order to reduce the vacuum at the suction side of the exhauster in the event that overheating is occurring, the exhauster includes a valve arrangement indicated generally at 28. As best seen in Fig. 2, the valve 28 includes an annular body member 30 which is screwed into a tapped bore 32 in the exhauster housing. The outer end of the body member 30 defines a frusto-conical valve seat 34 which is adapted to co-operate with a frusto-conical closure member 36 carried by one end of a pin 38. The other end of the pin 38 engages a thermostat unit 40 contained in a chamber 42 of the exhauster housing whereby, when the temperature at the thermostat unit 40 exceeds a pre-determined temperature, the pin is displaced to the left as viewed in Fig. 2 to lift the closure member 36 from the valve seat 34 against the action of a helical coil spring 44 which acts in a sense to hold the valve closed. Opening of the valve admits atmospheric air to enter a housing cavity 46 which communicates directly with the housing chamber 20 in the suction region whereby to reduce the vacuum pulled by the exhauster. This has the effect of reducing the temperature in the section region so that the valve eventually closes again.
  • The valve thus provides a means of limiting the temperature variations for the exhauster without losing the capability of pulling full rated vacuum.
  • It should be noted that the invention is not limited to the particular valve configuration and position illustrated and any valve may be used which admits air to the suction side in dependence upon a predetermined temperature in the exhauster being exceeded.

Claims (3)

1. An exhauster having a rotor (10) eccentrically mounted within a chamber (20) in a stationary housing (12) to draw in air from a suction region and deliver this air through an outlet port, and a valve (28) which selectively admits the entry of atmospheric air to said suction region, characterised in that the valve (28) is controlled by a temperature responsive control means which is arranged to open the valve (28) from its normally closed position when the operating temperature of the exhauster exceeds a predetermined value, thereby temporarily reducing the vacuum pulled by the exhauster, and automatically to close said valve (28) again when the operating temperature of the exhauster falls below said predetermined value, whereby the exhauster returns to pulling full vacuum.
2. An exhauster as claimed in claim 1, wherein the valve (28) comprises a snifter valve controlled by a thermostat (40) located in a chamber (42) in the housing (12) of the pump.
3. An exhauster as claimed in claim 2, in which the valve (28) has an annular body member (30) received in a tapped bore (32) in the exhauster housing, the outer end of the body member (30) defining a frusto-conical valve seat (34) which is adapted to co-operate with a frusto-conical closure member (36) carried by one end of a pin (38), the other end of the pin (38) engaging the thermostat (40) contained in said chamber (42) whereby when the temperature at the thermostat exceeds said predetermined value the pin (38) is displaced longitudinally so as to lift the closure member (36) from the valve seat (34) against the action of a coil spring (44) which acts in a sense to hold the valve (28) closed.
EP82302456A 1982-05-14 1982-05-14 Safety arrangement for a vacuum pump Expired EP0094457B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE8282302456T DE3269580D1 (en) 1982-05-14 1982-05-14 Safety arrangement for a vacuum pump
EP82302456A EP0094457B1 (en) 1982-05-14 1982-05-14 Safety arrangement for a vacuum pump
AT82302456T ATE18459T1 (en) 1982-05-14 1982-05-14 SAFETY ARRANGEMENT FOR VACUUM PUMP.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP82302456A EP0094457B1 (en) 1982-05-14 1982-05-14 Safety arrangement for a vacuum pump

Publications (2)

Publication Number Publication Date
EP0094457A1 EP0094457A1 (en) 1983-11-23
EP0094457B1 true EP0094457B1 (en) 1986-03-05

Family

ID=8189670

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82302456A Expired EP0094457B1 (en) 1982-05-14 1982-05-14 Safety arrangement for a vacuum pump

Country Status (3)

Country Link
EP (1) EP0094457B1 (en)
AT (1) ATE18459T1 (en)
DE (1) DE3269580D1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0153968B1 (en) * 1984-03-03 1987-12-23 Vickers Systems GmbH Power steering pump
DE9011624U1 (en) * 1990-08-09 1991-12-12 Siemens Ag, 8000 Muenchen, De
US5141407A (en) * 1990-10-01 1992-08-25 Copeland Corporation Scroll machine with overheating protection
ITMO20010176A1 (en) * 2001-08-31 2003-03-03 Esam Spa ADJUSTMENT DEVICE FOR COMPRESSORS - ASPIRATORS

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB276541A (en) * 1926-11-30 1927-09-01 Westinghouse Air Brake Co Improvements in or relating to fluid compressors
US2124390A (en) * 1935-05-07 1938-07-19 Gen Electric Vacuum pump apparatus
US2768585A (en) * 1952-12-18 1956-10-30 Schwitzer Corp Pump control mechanism
GB752133A (en) * 1953-05-07 1956-07-04 Bendix Aviat Corp Fluid pumping system and regulating means therefor
US3918848A (en) * 1972-04-27 1975-11-11 Abex Corp Fluid pressure energy translating device
CA1012840A (en) * 1974-03-29 1977-06-28 William J. Benson Fluid energy translating device

Also Published As

Publication number Publication date
EP0094457A1 (en) 1983-11-23
ATE18459T1 (en) 1986-03-15
DE3269580D1 (en) 1986-04-10

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