Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-03-22
2001-07-24
Lefkowitz, Edward (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S618000, C340S623000, C073S29000R, C073S306000, C073S307000
Reexamination Certificate
active
06265980
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a time delayed fluid level monitoring device and in particular, but not exclusively, to a time delayed fluid level monitoring device for monitoring the level of oil in a compressor of a refrigeration system.
BACKGROUND TO THE INVENTION
In most machines and apparatuses which use oil in their operation or for lubrication, it is important to ensure that the oil level does not drop below a predetermined level. Due to the normal operating characteristics of many of these machines and devices, it is common for there to be a temporary drop in the level of oil within a sump although the oil level within the whole machine or apparatus remains at an acceptable level. In such instances, it is not appropriate to provide an alarm or other warning of the drop in oil level. Such an alarm would give the false impression that the overall oil level is inadequate and result in further oil being added which in itself may have adverse effects.
To avoid the above situation, it is known to provide oil level switches or monitoring devices which have in-built electronic time delays. These devices will not give an indication of a low oil level unless the level remains low for a predetermined period of time. However, the electronic implementation of time delays has several inherent problems. One difficulty, relates to the interfacing with the electrical supply associated with the machine or apparatus. For example, in a refrigeration system, the supply voltage may be between 20 volts to 240 volts AC. Also, the frequency of the supply can vary from system to system and country to country. For example, the mains frequency in Australia is 50 hertz whereas in the USA it is 60 hertz. In addition, while electronic circuits can relatively easily provide short time delays using simple capacitor circuits, to produce long time delays digital circuits and/or software control is required. This increases the complexity and costs of the time delay monitoring device.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a robust and simple time delayed fluid level monitoring device in which the time delay provided is mechanically implemented.
According to the present invention there is provided a time delayed fluid level monitoring device for monitoring the level of a fluid in a vessel comprising:
a housing adapted for connection to said vessel and defining a cavity, said housing further provided with first and second orifices for allowing fluid communication between said cavity and the interior of said vessel, said first orifice arranged to restrict the flow of fluid between said cavity and said vessel in a manner so that there is a time delay in the equilisation of fluid level in fluid level in said vessel and in said cavity following a change of fluid level in the vessel, said second orifice arranged to provide a vent for said cavity; and,
means adjustably supported by the housing for providing an indication whether the fluid level in the cavity is above or below a predetermined level, the position of the means being adjustable to allow adjustment of the predetermined level;
whereby, in use, the indication provided by said means will only change from a current indication if the fluid level in the vessel has been at a level relative to said predetermined level opposite to the current indication for a period of time equal or greater than said time delay.
Preferably said orifices are spaced on opposite sides of said predetermined level.
Preferably the diameter of a lower one of said orifices controls the period of said time delay, such that the time delay varies proportionally with the diameter of the lower orifice.
Preferably said second orifice is of a diameter such that a layer or film of fluid on a face of said housing onto which said second orifice opens cannot bridge said second orifice.
Preferably said means comprises a float pivotally supported in said cavity and a switch activated by said float.
Preferably said switch is magnetically activatable and is retained in a casing which passes through said cavity and is detachably coupled to said housing.
Preferably said casing can be passed through said housing in opposite directions so that said means can be arranged to be in either a normally OFF or normally ON state when said fluid level is below said predetermined level.
REFERENCES:
patent: 3552726 (1971-01-01), Kraft
patent: 3886028 (1975-05-01), Hindin et al.
patent: 4083387 (1978-04-01), Stieber et al.
patent: 4523791 (1985-06-01), Belart et al.
patent: 4631375 (1986-12-01), McCann
patent: 5526883 (1996-06-01), Breaux
patent: 5680791 (1997-10-01), Joynt
patent: 52049/64 (1966-05-01), None
patent: 2718295 (1978-10-01), None
patent: 2321662 (1977-03-01), None
patent: 1599697 (1981-10-01), None
patent: WO 83/02824 (1983-08-01), None
Lefkowitz Edward
Refrigerant Monitoring Systems Pty Ltd.
Sheridan & Ross P.C.
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