Patent Application
20060032240
a) Field of the Invention
The invention is directed to a valve device for connecting to a cryopump. The invention is further directed to a pump arrangement comprising a cryopump with a backing pump connection flange to which a valve device is connected.
The valve device comprises a purge gas line in which a purge valve is arranged and which serves to supply a purge gas to the cryopump during a regeneration process of the cryopump.
b) Description of the Related Art
Cryopumps are known. They have cooled adsorption surfaces for adsorbing gases. A regeneration in which the adsorption surface is heated is occasionally required. Adsorbed gas containing hydrogen, for example, is released during regeneration. In order to prevent any risk owing to released gas, for example, to prevent the risk of explosion, a purge gas which dilutes the released gas is supplied during regeneration of the cryopump. The purge gas is an inert gas, usually nitrogen. A supply line arranged inside the cryopump serves to supply the purge gas to the adsorption surfaces. In known cryopumps, a connection flange is arranged at the housing of the cryopump. A purge gas line through which the purge gas is supplied can be connected to the supply line by means of the connection flange. A purge gas valve which can be opened and closed is arranged in the purge gas line.
The gas released during the regeneration process, together with the supplied purge gas, leads to an overpressure which is relieved through a pressure relief valve. This pressure relief valve is usually arranged at an intermediate piece which is connected to a backing pump connection flange of the cryopump on one side and to a backing pump valve on the other side. The backing pump valve leads to a backing pump by means of which the cryopump and a vacuum chamber to which the cryopump is connected can be pumped down to a pre-vacuum or roughing pressure. The backing pump valve is usually constructed as an angle valve or corner valve.
As a further safety precaution, a diluting gas which is an inert gas, usually nitrogen, is mixed in with the gas flowing out of the pressure relief valve during a regeneration process of the cryopump.
Servicing or exchange of the cryopump in a conventional pump arrangement of the kind described above is relatively complicated because of the parts to be disassembled.
One object of the invention is to simplify servicing or exchange of a cryopump.
Another object of the invention is to provide a more compact valve device for connecting to a cryopump.
Another object of the invention is to reduce the quantity of required seals and connections in a cryopump with a valve device connected to it.
Another object of the invention is to make it possible to simplify a valve device for connecting to a cryopump.
A valve device, according to the invention, for connecting to a cryopump comprises a body with a through-channel and a connection flange at one end of the through-channel for connecting to a backing pump connection flange of the cryopump; a pressure relief valve which opens when the overpressure in the through-channel exceeds a limiting valve and which lets this overpressure out of the through-channel; a purge gas line in which a purge gas valve is arranged and which serves to supply a purge gas to a supply line of the cryopump during a regeneration process of the cryopump; wherein an end portion of the purge gas line by which the purge gas line can be connected to the supply line runs within the through-channel to the area of the end of the through-channel situated in the connection flange.
A pump arrangement, according to the invention, with a cryopump having a backing pump connection flange and with a valve device connected to the backing pump connection flange comprises a body of the valve device with a through-channel and a connection flange at one end of the through-channel for connecting to the backing pump connection flange of the cryopump; a purge gas line of the valve device in which a purge gas valve is arranged and which serves to supply a purge gas to a supply line of the cryopump during a regeneration process of the cryopump; wherein an end portion of the purge gas line runs within the through-channel of the body of the valve device and wherein the end portion of the purge gas line is connected to an end portion of the supply line when the connection flange of the body is connected to the backing pump connection flange of the cryopump, and a continuous line is formed for the purge gas.
In a device according to the invention, when the body of the valve device is connected to the cryopump a connection of the purge gas line of the valve device to the supply line of the cryopump is accordingly carried out at the same time. This facilitates assembly when installing the cryopump and when disassembling it subsequently for maintenance purposes. It is not necessary for the connection between the purge gas line and the supply line to be completely tight.
In a preferred embodiment example of the invention, the body also has a dilution gas line in which a dilution gas valve is arranged, so that a dilution gas flowing out of the dilution gas line can be mixed in with the gas flowing through the pressure relief valve by means of the dilution gas line.
In a particularly advantageous embodiment form of the invention, a closure member is adjustably mounted in the body and the through-channel of the body can be closed and opened by means of this closure member. The body accordingly forms a valve body (or a valve housing) of a backing pump valve by means of which the connection to a backing pump can be blocked or released. The backing pump valve is advantageously constructed in the manner of an angle-valve or corner valve. Further, the purge valve is advantageously arranged at the body. Further, the dilution gas valve can advantageously be arranged at the body. In this way, a valve device which is very compact in its entirety and which is very easy to mount on and remove from the cryopump can be provided for connecting to the cryopump.
Further advantages and details of the invention will be described in the following with reference to the embodiment example shown in the drawings, further objects of the invention following therefrom.
In the drawings:
For the description of an embodiment example of the invention, reference is had first to the highly schematic and simplified
The pump arrangement 1 further comprises a valve device 8 for connecting to the cryopump 4. The valve device 8 has a body 9 with a through-channel 10 and a connection flange 11 at one end of the through-channel 10. The connection flange 11 of the body 9 of the valve device 8 is connected to the backing pump connection flange 7 of the cryopump 4.
The valve device 8 further comprises a purge gas line 12 in which a purge gas valve 13 is arranged. The purge gas line 12 serves to supply a purge gas to the cryopump during a regeneration of the cryopump. For this purpose, the purge gas line 12 is connected to the supply line 5 as will be described more fully hereinafter.
The valve device 8 further comprises a pressure relief valve 14 through which overpressure can be let off from the through-channel 10 through an overpressure outlet channel 28. Overpressure of this type occurs during a regeneration process of the cryopump 4.
The valve device 8 further comprises a dilution gas line 15 in which a dilution gas valve 16 is arranged. When the dilution gas valve 16 is opened, a dilution gas which flows in through the dilution gas line 15 and out of the latter can be mixed with the gas flowing off through the pressure relief valve 14.
The purge gas and the dilution gas are inert gases. The same gas, preferably nitrogen, can be used for both gases.
The pressure in the through-channel 10 can be picked up by means of a pressure sensor 17.
A closure member 18 is adjustably mounted in the body 9. The through-channel 10 can be closed and opened by means of this closure member 18. The closure member 18 is adjustable between the open position and closed position by means of an actuating member 19 which is constructed as a piston-cylinder unit in the present embodiment example. In the closed position, the closure member 18 contacts a valve seat 20. A vacuum valve is formed in this way.
At the other end of the through-channel 10, the body 9 has another connection flange 21 for connecting a backing pump 22. The backing pump 22 is connected to the body 9 by a line piece 23.
When the closure member 18 is open, the cryopump 4 can be pumped down to a roughing pressure by the backing pump 22 and when the cut-off valve 2 is open the vacuum chamber 3 can also be pumped down to a roughing pressure by the backing pump 22.
The body 9 and the closure member 18 which is adjustably arranged therein are constructed in the manner of a corner valve, i.e., the body 9 has two portions at an angle to one another, preferably at right angles to one another, through which a portion of the through-channel 10 extends, and the closure member is adjustable in axial direction of the one portion of the body 9 and through-channel 10, respectively, and can contact the valve seat 20 and be lifted from the latter.
The valve device is shown more exactly in FIGS. 2 to 9, wherein the parts described above with reference to
The construction of the pressure relief valve 14 in the shape of a self-locking check valve is shown more exactly in
The shape of the portion of the dilution gas line 15 located in the body 9 can be seen most clearly in
As can be seen most clearly in
In this way, a kind of pipe-within-a-pipe arrangement is provided in the end portion 32 of the purge gas line 12. The body 9 forms the outer pipe and the end portion 32 of the purge gas line is formed by the inner pipe.
In the area outside the body 9, the purge gas line 12 and the dilution gas line 15 run through the valve body 33 of the purge gas valve 13 and dilution gas valve 16 which are constructed as diaphragm valves. Actuating pistons 34, 35 are displaceably mounted in the cylinder housings 36, 37 at which are arranged actuating shafts which actuate diaphragms 38, 39. In the embodiment example shown here, springs 61, 62 act on the actuating pistons 34, 35 in the positions in which the diaphragm valves are open.
Upstream of the purge gas valve and dilution gas valve 16, the purge gas line 12 and dilution gas line 15 come together to provide a common connection 40 at the valve body 33 for supplying the purge gas and dilution gas, preferably nitrogen.
The purge gas valve 33 and dilution gas valve 16 are controlled in a conventional manner by control valves 41, 42 which are arranged at the valve body 33. Another control valve 43 which is likewise arranged at the valve body 33 serves to control the actuating member 19 for the closure member 18 (via the compressed-air line 44). Further, a compressed-air connection 45 through which the compressed air is supplied for adjusting the actuating pistons 34, 35 and actuating member 19 is provided at the valve body 33.
A connection flange 46 of the body 9 is used for connecting the pressure sensor 17 (see
As can be seen particularly in
As can be seen particularly in
On the other hand, the connection between the end portions 51, 32 could also be constructed in a vacuum-tight manner, preferably by means of an elastomer seal which is arranged at one of the two end portions and which is pressed against a sealing surface at the other end portion when connecting the end portions 51, 32.
The insertable continuation 54 could also be dispensed with in principle and the two end portions 51, 32 could be placed against one another at their front sides in order to connect them.
The end area 5 of the supply line inside the cryopump can be constructed in a conventional manner; this is not shown exactly in the drawing and need not be described more precisely. The adsorption surfaces of the cryopump are also not illustrated in the drawing and can be constructed conventionally.
The end portions 32, 51 of the purge gas line 12 and supply line 5 are located in the area of the central longitudinal axis 55 of the through-channel 10 or in the area of the central longitudinal axis of the backing pump channel 6 in the embodiment example that is shown. Eccentric arrangements are also conceivable and possible in principle. In the present embodiment example, the connection of the end portions 32, 51 is effected in the area of the connection plane between the connection flange 11 of the body 9 and the backing pump connection flange 7 of the cryopump 4. An arrangement which is to some degree outside of this plane would also be conceivable and possible. In that case, one of the two end portions 32, 51 would project from the through-channel 10 and backing pump channel 6 and the other would be set back in a corresponding manner.
A functional diagram of the valve device is shown in
The dilution gas valve 16 in the dilution gas line 15 is adjusted between its closed and open state in an analogous manner by the control valve 42.
The closure member 18 of the vacuum valve 63 is also adjusted between its closed state and its open state by the control valve 43 in an analogous manner.
The pressure relief valve 14 opens when there is an overpressure above the limit value in the through-channel 10 and lets this overpressure out through the overpressure outlet channel 28 into which the dilution gas line 15 opens. The dilution gas line 15 has a smaller cross section than the overpressure outlet channel 28.
In the functional diagram according to
When carrying out a regeneration process of the cryopump 4 in which its adsorption surfaces are heated in a conventional manner, the purge gas valve 13 is opened by means of the control valve 41 and purge gas is supplied to the cryopump 4 through the purge gas line 12 and the supply line 5. The gas released during the regeneration process together with the supplied purge gas result in an overpressure in the through-channel 10. At a determined value of this overpressure, for example, at a pressure of 0.2 bar above atmospheric pressure, the pressure relief valve 14 opens. The dilution gas valve 16 can be actuated by means of the control valve 42 depending upon the pressure in the through-channel 10 which is detected by the pressure sensor 17. In this respect, the dilution gas valve 16 can be opened at a pressure somewhat below the opening pressure of the pressure relief valve 14.
The cut-off valve 2 is closed during the regeneration process and the closure member 18 is in its closed position.
Various modifications of the embodiment example described herein are conceivable and possible without departing from the field of the invention. For example, instead of a corner valve, a straight valve could also be formed by means of the body 9 with the closure member 18 adjustably supported therein. It would also be conceivable and possible that the valve device 8 does not form a fore-valve, i.e., there is no a closure member 18 adjustably mounted in the body 9 by which the through-channel 10 can be closed. In this case, the valve device 8 can form an intermediate piece and a fore-valve by which the backing pump is closed can be connected to its connection flange arranged on the side remote of the cryopump 4. However, an embodiment form of this kind is less preferable due to the greater number of parts required.
When a sufficient dilution of the gas escaping during the regeneration process of the cryopump is achieved by means of the purge gas, the purge gas line 12 and the purge gas valve 13 could also be dispensed with.
Instead of adjusting the actuating pistons 34, 35 and the actuating member 19 by means of compressed air, this adjustment could also be carried out by means of another gas under pressure, particularly nitrogen.
As will be appreciated from the preceding description, the field of the invention is not limited to the embodiment examples shown herein, but rather should be defined with reference to the appended claims together with their full range of possible equivalents.
