Pumps – Expansible chamber type – Plural pumping chambers
Patent
1998-10-27
2000-06-06
Walberg, Teresa
Pumps
Expansible chamber type
Plural pumping chambers
417531, 417491, 417523, 417521, 417556, 91399, 91396, 91410, 91443, 91170R, 92 24, 123532, 123 46, 205392, F04B 5310
Patent
active
060710969
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a pneumatic cylinder for actuating an adjustable element, especially a smoke exhaust damper in a smoke and heat exhaust system according to the preamble of claim 1.
Compressed-air tanks with a piston to which pressure can be admitted on both sides and having at least one working face which can be displaced by compressed air in a cylinder having at least one working chamber are used, for example, in smoke and heat exhaust systems (abbreviated: SHE systems) in order to open smoke and heat exhaust dampers automatically or by remote control by admission of compressed air to a cylinder space or cylinder chamber in the event of fire, so that produced smoke which would otherwise make rescue difficult or impossible can be exhausted and so that a central access for rescue is created. Opening of the heat and smoke exhaust dampers is also intended to prevent the development of heat buildup. The pneumatic cylinder used must meet stringent safety requirements. In this connection, it is also known how to provide pneumatic cylinders with end-position interlocks, which among other purposes are intended to ensure extensive safety against collapse. A specially advantageous end-position interlock, which is also suitable for immobilizing a piston rod of the pneumatic cylinder in intermediate position, is characterized in that an additional latching rod coaxial with the piston rod and displaceable theretoward up to a stop on the piston rod is provided, said latching rod limiting the piston rod to a partial stroke and in this partial-stroke position protruding into a latching cylinder disposed on a latching piston (EP 0363575 B1). In the latching cylinder there is displaceably provided an additional latching piston which embraces balls with a sleeve-like section in partial-stroke position, said balls engaging in an annular groove in the additional latching rod and otherwise being radially movable. The radially outwardly movable balls are released when the sleeve-like section is axially retracted. When a predetermined pressure is exceeded, the additional latching piston is brought into communication with the closest adjacent cylinder space via a pressure-controlled changeover valve. This immobilization of an intermediate position is combined with interlocking elements of the end-position interlocks in the form of balls, which are held by spring-loaded latching pistons in grooves of the piston rod.
Among the aforesaid safety requirements of the pneumatic cylinders being used, it is necessary that they open the smoke exhaust dampers coupled therewith in practically failsafe manner in the event of fire and hold them in open position, for which purpose one of the said end-position interlocks can be used. In order that opening of the smoke exhaust damper takes place reliably even in the event of fire, the pressure-conducting medium for SHE cylinders actuated by pressurized fluid is supplied via fire-protected lines. However, the use and assembly of fire-protected lines represents a considerable extra expense.
Another known option for fire-protected design of an SHE system constructed with an SHE cylinder comprises equipping the SHE cylinder with a gas-filled compression spring. This gas-filled compression spring, however, is sometimes not adequately reliable--not to mention the expense incurred therefor.
Furthermore, it is known that the SHE cylinder can be combined with a mechanical spring which stores sufficient spring energy that a smoke exhaust damper can be swiveled to its open position together with the movable parts of the SHE cylinder in the event of fire. Because of this additional spring, however, the SHE cylinder equipped therewith is voluminous and in particular is unmanageably long.
The object of the present invention is therefore to provide the most compact possible pneumatic cylinder of the type mentioned in the introduction, especially as an SHE cylinder, which operates successfully without additional (types of) auxiliary energy and without additional external lines, especially of fire-protect
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Fastovsky Leonid
Walberg Teresa
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