GB2087484A - Rotary vacuum-pumps - Google Patents

Rotary vacuum-pumps Download PDF

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Publication number
GB2087484A
GB2087484A GB8032896A GB8032896A GB2087484A GB 2087484 A GB2087484 A GB 2087484A GB 8032896 A GB8032896 A GB 8032896A GB 8032896 A GB8032896 A GB 8032896A GB 2087484 A GB2087484 A GB 2087484A
Authority
GB
United Kingdom
Prior art keywords
exhauster
valve
housing
vacuum
temperature
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.)
Granted
Application number
GB8032896A
Other versions
GB2087484B (en
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 GB8032896A priority Critical patent/GB2087484B/en
Publication of GB2087484A publication Critical patent/GB2087484A/en
Application granted granted Critical
Publication of GB2087484B publication Critical patent/GB2087484B/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
    • 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
    • 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

Abstract

In a sliding-vane type pump, to prevent overheating the pump housing 12 contains a valve arrangement 28 having a closure member 36 coupled to a thermostat 40, which above a predetermined temperature lifts closure member from its seat 34 to admit atmospheric air to the pumping chamber 20 on the suction side of the rotor 10. <IMAGE>

Description

SPECIFICATION Improvements in vacuum pumps 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 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 the present invention, there is provided an exhauster having a temperature responsive valve which is arranged to admit atmospheric air to the suction side of the exhauster in the event that the operation temperature of the exhauster exceeds a predetermined value.
Advantageously this 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 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 bearing 16, 1 8. The rotor is eccentrically mounted relative to a cylindrical chamber 20 defined within the housing 12 whereby radial vanes 22, radically 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 predetermined 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 suction 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.
1. An exhauster having a temperature responsive valve which is arranged to admit atmospheric air to the suction side of the exhauster in the event that the operating temperature of the exhauster exceeds a predetermined value.
2. An exhauster as claimed in claim 1, wherein the valve is disposed within the housing of the exhauster.
3. An exhauster as claimed in claim 1 or 2, wherein the valve comprises a snifter valve controlled by a thermostat located in a chamber in the housing of the exhauster.
4. An exhauster as claimed in claim 3, in which the valve has an annular body membe.r received in a tapped bore in the exhauster housing, the outer
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in vacuum pumps 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 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 the present invention, there is provided an exhauster having a temperature responsive valve which is arranged to admit atmospheric air to the suction side of the exhauster in the event that the operation temperature of the exhauster exceeds a predetermined value. Advantageously this 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 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 bearing 16, 1 8. The rotor is eccentrically mounted relative to a cylindrical chamber 20 defined within the housing 12 whereby radial vanes 22, radically 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 predetermined 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 suction 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
1. An exhauster having a temperature responsive valve which is arranged to admit atmospheric air to the suction side of the exhauster in the event that the operating temperature of the exhauster exceeds a predetermined value.
2. An exhauster as claimed in claim 1, wherein the valve is disposed within the housing of the exhauster.
3. An exhauster as claimed in claim 1 or 2, wherein the valve comprises a snifter valve controlled by a thermostat located in a chamber in the housing of the exhauster.
4. An exhauster as claimed in claim 3, in which the valve has an annular body membe.r received in a tapped bore in the exhauster housing, the outer end of the body member defining a frusto-conical valve seat which is adapted to co-operate with a frusto-conical closure member carried by one end of a pin, the other end of the pin engaging the thermostat contained in said chamber whereby when the temperature at the thermostat exceeds said predetermined value the pin is displaced longitudinally so as to lift the closure member from the valve seat against the action of a coil spring which acts in a sense to hold the valve closed.
5. An exhauster substantially as hereinbefore described with reference to the accompanying drawings.
GB8032896A 1980-10-11 1980-10-11 Rotary vacuum-pumps Expired GB2087484B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8032896A GB2087484B (en) 1980-10-11 1980-10-11 Rotary vacuum-pumps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8032896A GB2087484B (en) 1980-10-11 1980-10-11 Rotary vacuum-pumps

Publications (2)

Publication Number Publication Date
GB2087484A true GB2087484A (en) 1982-05-26
GB2087484B GB2087484B (en) 1984-05-16

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8032896A Expired GB2087484B (en) 1980-10-11 1980-10-11 Rotary vacuum-pumps

Country Status (1)

Country Link
GB (1) GB2087484B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2196696A (en) * 1986-10-22 1988-05-05 Utile Engineering Co Limited Rotary vane pumps operable in vacuum mode
DE102011078816B3 (en) * 2011-07-07 2012-12-20 Ford Global Technologies, Llc Electrically driven vacuum pump, particularly vane cell vacuum pump for motor vehicle, has control and monitoring unit, where opening is formed downstream of check valve, and opening is enclosed by refractory material

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2196696A (en) * 1986-10-22 1988-05-05 Utile Engineering Co Limited Rotary vane pumps operable in vacuum mode
US4826407A (en) * 1986-10-22 1989-05-02 The Utile Engineering Co. Ltd. Rotary vane pump with ballast port
GB2196696B (en) * 1986-10-22 1991-05-29 Utile Engineering Co Limited Pumps
DE102011078816B3 (en) * 2011-07-07 2012-12-20 Ford Global Technologies, Llc Electrically driven vacuum pump, particularly vane cell vacuum pump for motor vehicle, has control and monitoring unit, where opening is formed downstream of check valve, and opening is enclosed by refractory material

Also Published As

Publication number Publication date
GB2087484B (en) 1984-05-16

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19991011