JPH05154301A - Cold trap device - Google Patents

Abstract

PURPOSE:To provide a cold trap device capable of performing the efficient cold trapping of condensible gas in a high vacuum exhaust device for highly evacuating an objective container and capable of reducing the pipeline resistance to non-condensible gas. CONSTITUTION:Condensible gas can efficiently be discharged by condensation without bringing the lowering of the discharge speed of non-condensible gas only by arranging an L-shaped pipeline body 1 provided with a cooling plate 2 cooled over the entire inner wall surface thereof by a cooling medium between an objective container and a vacuum pump. Therefore, a vacuum pump small- sized as compared with a conventional one can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold trap device for condensing and capturing water vapor or oil vapor flowing in a pipeline, and particularly for use in a high vacuum exhaust device for raising a target container to a high vacuum. The present invention relates to a suitable cold trap device.

[0002]

2. Description of the Related Art Conventionally, a vacuum pump such as an oil diffusion pump is connected to exhaust a gas such as air in the container in order to make a target container highly vacuum. Also, in the target container installed in the conduit between the target container and the vacuum pump, particularly large amount of water vapor is condensed during the exhaust from the atmospheric pressure to increase the exhaust speed or flow backward from the oil diffusion pump side. There is a cold trap device that condenses oil vapor and suppresses it. The structure is, for example, Shokai Kai5.
As disclosed in Japanese Patent Laid-Open No. 5-141503 and Japanese Utility Model Laid-Open No. 61-139701, a cooling plate that is cooled with a refrigerant is provided in the exhaust pipe line, and the exhaust gas comes into contact with the cooling plate to generate water vapor. Is generally condensed and oil vapor from the pump side is also condensed and exhausted.

Liquid nitrogen, for example, is used as the above-mentioned refrigerant. Therefore, the condensable gas having a relatively high boiling point such as water vapor can be exhausted by the cold trap device and the exhaust speed can be increased, but the non-condensable gas having a relatively low boiling point such as oxygen gas and nitrogen gas can be Condensation cannot be expected, so the cold trap device cannot exhaust the gas.Furthermore, the cooling plate placed so as to block the pipe forcibly bypasses the gas and creates pipe resistance, which in turn reduces the exhaust speed. It was difficult to significantly increase the exhaust speed as a whole. Along with this, in a device that uses a non-condensable gas such as nitrogen gas as a process gas, it is necessary to install a large vacuum pump in order to secure an exhaust speed, and there is a problem that the cost thereof rises.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and its main purpose is to perform an efficient cold trap for a condensable gas and to It is an object of the present invention to provide a cold trap device capable of reducing the conduit resistance to a condensable gas.

[0005]

According to the present invention, the above-mentioned object is condensable in the conduit connecting the target container and the vacuum pump with a high-vacuum exhaust device for high-vacuating the target container. A cold trap device arranged to exhaust gas by condensation, comprising an L-shaped pipe body bent at an intermediate portion, a bent portion of the L-shaped pipe body, and the vicinity thereof. It is achieved by providing a cold trap device comprising a cooling plate and means for cooling the cooling plate with a refrigerant.

[0006]

According to the above-described structure, when the condensable gas molecules in the exhaust gas change in the direction in which the exhaust gas flows at the bent portion of the L-shaped pipe body, the cooling provided on the wall surface of the pipe line has a relatively large probability. It collides with the plate, condenses and is exhausted. Further, oil vapor or the like flowing back from the pump side also collides with the cooling plate mainly at the bent portion and is condensed and exhausted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan sectional view of the essential parts of a cold trap device showing a first embodiment to which the present invention is applied. This cold trap device includes an L-shaped conduit body 1 and an L-shaped conduit body 1.
Hollow cooling plate 2 arranged on the entire inner surface of the V-shaped conduit body 1.
And a pipe 3 for supplying liquid nitrogen to the coolant passage 2a in the cooling plate 2. An oil diffusion pump (not shown) is connected to the lower side or downstream side opening 1a of the L-shaped conduit body 1 in FIG. 1, and a vacuum is also not shown to the left side or upstream side opening 1b in the figure. A vacuum valve to be connected to the target container to be connected is connected. The L-shaped conduit body 1 has an opening 1 from the bent portion 1c at the center of the conduit.
As shown in FIG. 3, the upstream pipe length A up to b, the downstream pipe length B from the bent portion 1c to the opening 1a, and the opening size E of this pipe are A: E = E: ratio relationship B, that has become a size of a × B = E ^2, so that the can not pass without gas is in contact with the cooling plate.

Actually, when the oil diffusion pump is driven and the cold trap device is operated to evacuate the target container, the exhaust from the target container side is generated at the bent portion 1c in the L-shaped conduit body 1. The direction is changed to the lower side in the figure and it is discharged to the pump side. At this time, the condensable gas such as water vapor in the exhaust gas is opposed to the opening 1b of the L-shaped conduit body 1 by a face 1d.
Is contacted with the cooling plate 2 centered around the part, condensed and exhausted. At that time, as described above, in the L-shaped conduit body 1, the conduit projection length A on the upstream side of the bent portion 1c, the conduit projection length B on the downstream side, and the opening size E of the conduit are A: E = E. Since the ratio of B is: B, for example, even if the gas passes through the shortest path s indicated by the imaginary line, the gas always comes into contact with the cooling plate, so that water vapor and the like are surely condensed and exhausted. Is able to. On the other hand, the oil vapor flowing back from the oil diffusion pump side is the surface 1 facing the opening 1a of the L-shaped conduit body 1.
It contacts the cooling plate 2 centered on the portion e, is condensed and exhausted. Since the direction of the pipeline changes only for the exhaust as a whole, it produces a pipeline resistance equivalent to that of a bent portion in a normal pipeline, and a cooling plate is placed to block the conventional pipeline. The duct resistance is significantly reduced compared to the cold trap device.

The following are the exhaust rates of water vapor, nitrogen, and oxygen when using the cold trap device to which the present invention is actually applied, the exhaust rate when a pipe is installed instead of the cold trap, and Table 1 shows the evacuation speed in the case of using a cold trap device with a cooling plate arranged so as to block the pipeline under the same size conditions.

[0011]

[Table 1]

As described above, when the cold trap device to which the present invention is applied is used, the evacuation rate of water vapor, that is, the condensable gas is remarkably improved, and the evacuation rates of nitrogen and oxygen gases are not provided. It can be seen that it has the same ability as. Therefore, the cold trap device to which the present invention is applied is extremely effective particularly in a device using nitrogen gas as the process gas.

FIG. 2 is a view similar to FIG. 1 showing a second embodiment to which the present invention is applied. The same parts as those in FIG. 1 are designated by the same reference numerals and their detailed description will be omitted. . According to this embodiment, the cooling plate 12 provided on the entire inner surface of the L-shaped conduit body 11 is not hollow and is made of a metal plate having high thermal conductivity. Further, a refrigerant tank 14 in which liquid nitrogen is received is in contact with a part of the cooling plate 12 near the bent portion 11c, and the cooling plate 12 is cooled by coming into contact with the liquid nitrogen. ing. The refrigerant tank 14 is provided with a pipe 15 for supplying a refrigerant and a pipe 16 for discharging a vaporized refrigerant, so that the refrigerant is replenished and discharged. The other structure is the same as that of the first embodiment.

[0014]

As is apparent from the above description, an L-shaped conduit body provided with a cooling plate that is cooled by the refrigerant over the entire inner wall surface is provided between the target container and the vacuum pump. However, since the exhaust speed of the non-condensable gas is significantly improved without lowering the exhaust speed of the non-condensable gas, the water vapor in the target container and the reverse flow steam from the pump side, which are often present when exhausting from atmospheric pressure, are significantly increased. It is particularly effective for exhausting the gas, and since it is possible to prevent a decrease in the exhaust speed for the process gas such as nitrogen, it is possible to use a vacuum pump smaller than the conventional one. From the above, the effect of the present invention is great.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a cold trap device showing a first embodiment to which the present invention is applied.

FIG. 2 is a plan sectional view of a cold trap device similar to FIG. 1 showing a second embodiment to which the present invention is applied.

[Explanation of reference numerals] 1 L-shaped conduit body 1a Downstream opening 1b Upstream opening 1c Bent portion 1d, 1e surface 2 Cooling plate 2a Refrigerant passage 3 Pipe 11 L-shaped conduit body 11c Bent portion 12 Cooling plate 14 Refrigerant Tanks 15 and 16 pipes

Claims (3)

[Claims] 1. A cold trap device arranged to exhaust a condensable gas by condensing in a pipe line connecting the target container and a vacuum pump with a high-vacuum exhaust device for making the target container a high vacuum. And an L-shaped conduit body that bends at an intermediate portion, a bent portion of the L-shaped conduit body and a cooling plate disposed in the vicinity thereof, and means for cooling the cooling plate with a refrigerant. A cold trap device comprising: 2. The cooling means for the cooling plate has a refrigerant passage formed in the entire cooling plate, and a pipeline for supplying a refrigerant to the passage from the outside. Cold trap device. 3. The L-shaped conduit body is such that the product of the protruding length on the upstream side of the bent portion and the protruding length on the downstream side of the bent portion is equal to the square of the opening size of the conduit body. The cold trap device according to claim 1 or 2.