DE1059144B - Automatic protection valve for vacuum or high vacuum systems - Google Patents

Description

The object of the invention relates to an automatically operating protection valve for vacuum or High vacuum systems, consisting of a main valve between the mechanical pump and a closed evacuating space or high vacuum pump and one between mechanical pump and main valve located ventilation valve.

When operating vacuum systems, especially high vacuum systems, it can very easily happen that when the mechanical pump is switched off, when it is started up again or in the event of malfunctions the same, the oil used to seal this pump in liquid form or as an oil foam from Atmospheric pressure is forced into the vacuum space. This oil ingress in the evacuated Space can be very damaging to its contents and also to the system itself, and it can be utterly costly and require time-consuming cleaning of the entire system and its contents. Most notably Such an ingress of oil in electron microscopes and the like is disastrous.

Furthermore, some work in the vacuum space, e.g. B. Vacuum distillations of easily oxidizable Substances, as well as downstream high vacuum pumps, especially when switched on repeatedly the pump, a very precisely maintained vacuum in the fore-vacuum space before the recipient or the high vacuum pump is switched on.

In order to solve this requirement, the ones necessary for a perfect operation of the plant were often used up to now various valve actuations with simultaneous monitoring of the measuring instruments by hand carried out, Avas required a strong concentration of the operator.

For this purpose, shut-off devices in the manner of a three-way valve are known which, although the necessary Allow valve actuations to be carried out only in the correct sequence, but operated by hand must be, but still the right moments for the various individual activities to be determined by the operator according to measuring instruments or experience.

In the event of a sudden unnoticed failure of the mechanical pump, however, oil ingress was still in the vacuum space is almost inevitable.

There are also known automatic valve combinations controlled by measuring instruments, their technical expenditure on measuring devices, control magnets, relays, delay elements, etc. very much is high and are therefore very prone to failure and expensive. -

In particular, for example, for the perfect automatic cooperation of the ventilation valve and the main valve when starting up or restarting the automatic safety valve
for vacuum or high vacuum systems

Applicant:
Jenoptik Jena GmbH, Jena

Werner Haunstein, Jena,
and Hans Zapfe, Jena-Zwatzen,
have been named as inventors

operation of the system also requires complicated measuring and control equipment, which after switching on the oil shift pump and the simultaneous automatic closing of the ventilation valve, the main valve Open only when the prevailing vacuum in the fore-vacuum space has reached a level that the Switching on the recipient or keeping the high vacuum pump closed without damaging the system or their content is permitted.

According to the invention, these deficiencies are eliminated and the demands made in particular with regard to Reliability and simplicity met in that the open vent valve has an adjustable Passage has that the main valve and the ventilation valve are combined into one unit, that after switching on the mechanical pump a fixed adjustable delay device controlled by this The ventilation valve only closes when there is a pump output in the valve housing and resulting from adjustable ventilation valve passage, for the continued operation of the system favorable negative pressure is achieved with certainty and that the ventilation valve with known means so is coupled to the main valve that only immediately after it has completely closed the main valve is opened and, conversely, when the mechanical pump is switched off or suspended immediately close the main valve before opening the ventilation valve.

An embodiment of the subject matter of the invention is shown in the drawing, namely shows

Fig. 1 in the scheme of a high vacuum pumping system

909 530/106

Claims (1)

with a large protection valve and not to scale for the sake of clarity Fig. 2 is a diagram that explains how the protection valve works. When the plant is idle, as shown in Fig. 1 , the valve housing! between air pump 2 and line 4 leading to high vacuum pump 3 via an open ventilation valve consisting of valve seat 5, valve disk 6 and adjustable nozzle 7. At the same time, the valve disk 8 of the main valve between the housing 1 and the high vacuum pump 3 is pressed onto its seat 10 by the action of the compression spring 9. When a switch 11 is actuated, the air pump 2 is driven by a motor 12. Simultaneously a centrifugal switch 13 coupled to this pump also comes into action, which is activated when Working speed of the pump responds and a. Delay relay 14 of a few seconds running time in Activity sets. Before this delay relay 14 is triggered, the pump 2 has had enough time to around the housing 1, with the ventilation valve 5, 6 still open, to an adjustable position through the nozzle 7 Pressure to evacuate. The gas stream flowing in through this nozzle is then in equilibrium with the gas flow conveyed by the air pump 2. It now prevails in the valve housing Vacuum, which corresponds to the "harmless pressure" for the high vacuum pump 3. Only after achieving it In this state, the delay relay 14 switches on a solenoid 15 which has a core 16 in overcoming the force of the compression spring 9 pulls into itself. This also makes the one with the core 16 firmly connected body 17 and the arm 18 located thereon moved in the same direction. The shaft 19 of the valve disk 6 loaded by the spring 20 follows the arm 18 until the ventilation valve 5, 6 is closed is. Only then does the shaft 21 of the valve disk 8 come with its mushroom-shaped cap 22 as a result of the Action of the compression spring 23 a.n the inner wall 24 of the body 17 to rest, and after further movement of the body 17, which takes place in fractions of a second, the valve disk 8 lifts off his seat 10. In this way, the two valves as a result of the telescopic-like Valve spindle, which is composed of parts 16, 17, 21, 22 and 23, in extremely rapid Sequence moved one after the other without the valves being open at the same time for just a moment. When the pump drive 12 is switched off by means of the switch 11 or when the centrifugal switch 13 responds in the event of malfunctions, the solenoid 15 is instantaneously de-energized. The core 16 with the body 17 flips again due to the action of the compression spring 9 in the position shown in fig. 1 position again, wherein first of all the sets by the compression spring 23 from the body 17 postponed shaft to the valve disc 8 on the valve seat 10 and the Line 4 to high voltage pump 3 and the adjoining recipient 25 shut off. Immediately thereafter, the arm 18 of the body 17 presses the valve disk 6 of the ventilation valve from its seat 5. The valve housing 1 can now be ventilated through the adjustable nozzle 7, and oil ingress into the valve housing and into the further pumping system is prevented. Only by changing the adjustable nozzle 7 you have it in your hand, the pressure in the valve housing to adapt to the respective requirements without on the delay relay 14 an adjustment or on the rapid actuation sequence of the two valves a change needs to be made. In the diagram of Fig. 2, two curves are shown, of which curve I shows the pressure curve in the main valve housing of previously known devices starting from atmospheric pressure P ₁ , while curve II shows the pressure curve when using the device according to the invention. So far, according to curve I at A at time t _t , the ventilation valve had to be closed at the same time as the air pump was switched on. As soon as the pressure p _{2 was reached} at B , the recipient or the high vacuum pump had to be switched on. For this purpose, a complicated, expensive and failure-prone control device is required for the two separately working A 'valves, since switching on too early or too late in point C or D would occur at other pressures that may be harmful to the system. According to the invention, this cannot occur. At point A (curve II) only the air pump is switched on. The ventilation valve with the adjustable nozzle is still open. The nozzle is set so that at the desired pressure ^ _{2 there is} a state of equilibrium between the gas flow flowing in through the nozzle and the gas flow conveyed by the air pump. This condition is reached at point E, and from there the curve is horizontal. At E , the ventilation valve could now be closed at the earliest and the main valve to the recipient or to the high vacuum pump could be opened. However, since delays of a few seconds are not important in most cases, the two valve actuations, which can now take place with an always constant, very small time interval (due to the telescopic spindle), are set to a later point in time t _s at point F for the closing of the ventilation valve and shortly thereafter at time i ₄ at point G for the opening of the main valve. This has the advantage that, for example, when the nozzle opening is changed, i.e. with the curves marked II '(larger nozzle) and IT "(smaller nozzle), the valves in the horizontal part of the curve, namely after points E' and E have been reached ", are operated. Claim: Automatic protection valve for vacuum or high vacuum systems, consisting of a main valve between mechanical pump and a room to be evacuated or a high vacuum pump and a ventilation valve located between the mechanical pump and the main valve, thereby characterized in that the open ventilation valve (5, 6) has an adjustable passage (7) possesses, the main valve (8, 10) and the ventilation valve (5, 6) combined into one unit are that after switching on the mechanical pump (2) one controlled by this fixed adjustable delay device (14) only closes the ventilation valve (5, 6) when in the valve housing (1) a pump output and an adjustable ventilation valve opening (7) the resulting negative pressure, which is favorable for the continued operation of the system, has been reached with certainty, and the ventilation valve (5, 6) with known ones