Rotary kinetic fluid motors or pumps – With control means responsive to non-cyclic condition...
Reexamination Certificate
1998-10-08
2001-08-21
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With control means responsive to non-cyclic condition...
C415S051000, C415S118000, C415S169200, C137S187000, C137S204000
Reexamination Certificate
active
06276894
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for draining condensate from compressed-gas systems, an arrangement hereof as well as the use of a device for draining off condensate for a method for draining condensate from compressed-gas systems.
2. Description of the Prior Art
A method for draining condensate from compressed-gas systems as for example a compressed air-, steam- or other systems, is known from the EP 391 250 B1 which teaches a device for draining off condensate in a special construction. This device for draining off condensate embodies a known arrangement for draining off condensate from compressed-gas systems.
Furtheron a method and a device for draining condensate off is known from GB-A-2074702, this device is suited for vapor-pressure units. In a T-shaped housing a sensor protrudes into a collection chamber, in which condensate can accumulate. When the sensor, senses condensate, a time delay circuit is activated, which opens an outlet valve but after a certain time after the sensing. Thereby, in a like way as in the JP-A-06 066 399, it is avoided that the outlet valve opens and closes too often and even for very small amounts of condensate.
According to the known state of the art the condensate draining from the compressed gas system is collected in a trap of the device for draining off condensate. At least one sensor, which registers the level of the condensate, preferably two such sensors are provided at different heights, project into the trap. As soon as the trap is filled up to the height of the upper sensor, a draining off process starts. The control electronics, which are provided in the device for draining off condensate, opens a solenoid valve, whereby the pressure in a control chambers of a diaphragm valve is diminished. The same is thereby lifted off its seat and gives way for the condensate to an outlet.
According to the state of the art the volume of the trap should be in a certain sensible relation to the amount of condensate which is collected in a certain timely process. The volume should be that large that the valve arrangement does not have to be opened too many times. If the trap is too small, then a variety of tappet clearances occur. A valve, may it be a diaphragm valve or an electromagnetic valve, possesses parts which are mechanically moved and which are subject to wear and tear. A secure function of the valve can only be ensured for a certain number of tappet clearances. If the trap is constructed too small, the number of tappet clearances is reached relatively fast, for example after a few weeks already or even earlier.
According to the state of the art large devices for draining off condensate with large traps are therefore provided for compressed-gas systems with a high amount of condensate, graduated to the needs there are a number of smaller devices for draining off condensate.
However, the larger devices for draining off condensate are clearly more expensive than the smaller ones and one tends to use a device for draining off condensate, which is as small as possible, because of the financial aspect. This again leads to a restriction of the service life of the movable parts.
SUMMARY OF THE INVENTION
This is where the invention starts. It is the task of the invention to declare a method for draining condensate off compressed-gas systems and an arrangement for such a draining off process, whereby a purging device which is of fairly small dimensions, can be used. This leads to another kind of usage of known devices for draining off condensate than according to the state of the art.
This task is solved according to the procedure by a method of draining condensate off from compressed-gas, e.g. compressed-air systems, by the fact that
1) a trap for condensate is provided, in which condensate collects during operation of the compressed-gas system, the trap has an outlet through which the condensate, which collects can be drawn off and
2) a purging device is connected to the outlet and which has a) a sensor intended to detect the presence of condensate in the purging device, b) which comprises control electronics connected to the sensor including a timer circuit and c) which comprises a valve controlled by the control electronics and which influenced by the sensor, either shuts the purging device so that no condensate can escape through it or opens it each time the condensate level rises and the sensor switches over from indicating “no condensate”, to indicating “condensate present”, thus starting the timer circuit. On expiry of the time defined by the circuit, the valve is opened until the sensor indicates “no condensate” again, when the valve closes the purging device again.
In accordance with the device the task is solved by an arrangement according to claim
3
.
According to the invention the collection of condensate in a trap, which itself has no devices built in for a purging device, namely preferably does not comprise any sensors. A purging device is provided, which may have its own chamber itself, but which does not necessarily have it. This purging device may be used for draining off condensate as it is known from the EP 391 250 B1, and built in a simpler manner, such as in a tubular shape. At least one sensor positioned in the purging device is sufficient for the method according to the invention.
A decisive factor however is the control of the purging device. As the separate trap, which can be embodied relatively large, is emptied above the purging device, the valve arrangement of the purging device can stay in an open state for a relatively long amount of time and with it large amounts of condensate can be purged without the need of many tappet clearances.
The valve arrangement of the purging device is opened as soon as a period of time dictated by the timer circuit, has passed. The timer circuit is started, when the signal of the sensor switches from indicating “no condensate” to indicating “condensate present”. The valve arrangement is shut again when the sensor switches from indicating “condensate present” to indicating “no condensate”.
This method may be described as follows: In the trap, which preferably, but not necessarily, is part of the compressed-gas system, condensate is collected during operation of the system. As soon as the sensor switches from indicating “no condensate” to indicating “condensate present”, a time gate is opened, and within the time span dictated by this time gate the condensate can collect in the trap. The length of this time gate is the so-called time span. The time span is measured to maintain the that sufficient, operational security of the compressed-gas system—but not too much condensate can collect in the trap. When the time span has run out and thereby the time gate is shut, the valve arrangement is opened. Only the condensate collected within the time span can be drawn off. As soon as it is drawn off, the sensor switches from indicating “condensate present” to indicating “no condensate”, this again leads to shutting the valve arrangement.
Accordingly, the high amount of valve actuations necessary in devices for draining condensate off according to the prior art are avoided. A relatively small device can be used which is simpler and more inexpensive than known devices. For the producer of compressed-gas systems, for example compressed-air systems, this results in the possibility that the trap can be provided at a suitable position of the system. With regard to construction and costs this is simpler than to provide a separate chamber of sufficient volume in a device for draining off condensate. The trap may also be a separate receptacle, which is embodied in a relatively simple manner, and is connected to the compressed-gas system in a suitable manner. Similarly, the purging device is separately arranged again.
The time span, during which condensate, is collected, can be adjusted. That way the control electronics, can adjust to the respective operational conditions to save the time of drain off and evaluation. For example, the control electronics
Lezdey John
Look Edward K.
McAleenan James M.
LandOfFree
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