JPH0415285Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a filter for removing minute particles in low-temperature liquefied gas using a resin filtration membrane.

[Conventional technology]

In fields such as the semiconductor industry that use highly clean gases, not only particles in room-temperature gases but also particles in low-temperature liquefied gases have recently been removed.

Due to these requirements, filters using filtration membranes are generally used, but conventional filters for low-temperature liquefied gas use a metal filtration membrane made of a mesh-like thin film and a cylindrical reinforcing body with ventilation holes on the outer surface. It had a structure in which the attached elements were fixed and housed within the housing.

[Problem that the invention attempts to solve]

As mentioned above, metal filtration membranes are used in conventional low-temperature liquefied gas filters, but these metal filtration membranes have the problem of not being able to remove particles with a particle size of 20 μm or less due to the mesh structure. . Furthermore, in the past, when fixing an element in a housing, the reinforcing body of the element and the corresponding housing were connected by screws using a sealing material such as sealing tape, which caused problems with minute particles. In some cases, the threaded joint becomes a new source of particle generation. Therefore, it is possible to adopt a resin filtration membrane that can remove minute particles at room temperature, but even if you try to use a resin filtration membrane for low-temperature liquefied gas, the low-temperature liquefied gas piping is generally made of metal such as stainless steel or aluminum. Since reinforcing bodies, housings, etc. are also usually made of metal, there is a problem with adhesion between resin and metal. In addition, since low-temperature liquefied gas piping is used in a wide temperature range from the low temperature when low-temperature liquefied gas is flowing to the room temperature when it is not flowing, there is the problem of the difference in expansion coefficient between resin and metal, which makes it difficult to realize. Ta.

The object of the present invention is to provide a filter for low-temperature liquefied gas that solves the above-mentioned disadvantages.

[Means for solving problems]

The present invention is characterized by an element formed by covering a resin filtration membrane with a resin reinforcement body having a ventilation hole on the outer surface of a bottomed cylindrical body and a fitting part on the open end side; It consists of a metal housing consisting of a main body that houses the element and a lid member, and is configured such that a concentric fitting part is provided on the end face of the lid member and the fitting part is fitted so that the element is fixed to the lid member. Additionally, a bulge is provided on the inner fitting surface of the fitting portion, and an O-ring is provided between the outer fitting surface of the fitting portion and the outer peripheral surface of the fitting portion.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded sectional view of a low-temperature liquefied gas filter according to the present invention, and FIG. 2 is an enlarged sectional view of a fitting portion between a reinforcing body and a lid member.

In the figure, a filter 10 is composed of an element 13 formed by covering a reinforcing body 11 with a resin filtration membrane 12, and a housing 14 that removably accommodates the element 13. The reinforcing body 11 is made of resin and has a bottomed cylindrical body 11a with a ventilation hole 11b and a fitting part 11c on the open end side.
There are two rows of O-ring grooves 15a, 15 on the outer periphery of 1c.
b is formed. Then, the resin filtration membrane 12 is wound around the body 11a of the reinforcing body 11, and both ends of the wrapped membrane are thermally welded to the body 11a.
By doing so, the element 13 is constructed.

Next, the housing 14 includes the main body 14a and the lid member 14.
The main body 14a is formed into a cylindrical shape large enough to accommodate the element 13 and is connected to the pipe A, and the lid member 14b has a gas flow in the center. It has an opening that communicates with the outlet and is connected to the pipe B at one end, and a concentrically recessed fitting part 16 corresponding to the fitting part 11c of the reinforcing body 11 is provided on the other end surface. On the inner fitting surface 16a of the fitting portion 16, for example, two rows of protruding portions 17a protruding in a semicircular shape,
17b are provided at appropriate intervals along the circumferential direction. As will be described later, the bulging portions 17a and 17b strongly abut against the inner circumferential surface of the fitting portion 11c at low temperatures. is preferably curved.

In the above configuration, the insertion portion 11c of the reinforcing body 11
Flexible O-rings 18a, 18b made of silicone rubber or the like are attached to grooves 15a, 15b on the outer periphery of the element 13, and the fitting part 11c is inserted into the fitting part 16 of the lid member 14b to fix the element 13, and then the main body 14a and The filter 10 of the present invention is installed between the tubes A and B by tightly connecting the cover member 14b with the O-ring 19. When low-temperature liquefied gas flows in from the pipe A as shown by the arrow, the low-temperature liquefied gas is filtered by the filtration membrane 12 in the process of flowing from the outside to the inside of the element 13. In particular, in the filter 10 of the present invention, the filtration membrane 12 is made of resin. This makes it possible to remove and collect particles that are much smaller than conventional methods.

Next, in the filter 10 of the present invention, the reinforcing body 11 is made of resin, so the resin filtration membrane 12 can be airtightly attached to the reinforcing body 11 with sufficient strength even by ordinary heat welding, and the reinforcing body Since filtration membrane 11 and filtration membrane have the same coefficient of thermal expansion, even when used in a wide temperature range, filtration membrane 12
The thermally welded parts 12a, 12a at both ends will not deteriorate, and the filtration membrane 12 will not be able to maintain tension at the thermally welded parts 12a, 12a.

Moreover, the insertion part 11c of the reinforcing body 11 and the lid member 14
In the case of fitting with the fitting part 16 of b, both the fitting part 11c where the low temperature liquefied gas flows into the filter 10 and the fitting part 16 become low temperature and contract, but in this case, the fitting part 11c made of resin is smaller. Fitted part 16 made of metal
Since the fitting portion 11c contracts more, the inner circumferential surface of the fitting portion 11c strongly contacts the bulges 17a and 17b provided on the inner fitting surface 16a of the fitting portion 16, and is held airtight. Further, at room temperature, the O-rings 18a and 18b interposed between the outer circumferential surface of the fitting portion 11c and the outer fitting surface 16b of the fitting portion 16 keep the fitting airtight.

Next, a filter similar to that shown in FIG. 1 was manufactured and its performance was confirmed. At this time, the element has an inner diameter of 32 mm, a length of the inserted part of 15 mm, a length of the body part of 112 mm, a thickness of 0.2 mm in the body part of the reinforcing body made of fluorocarbon resin, and a thickness of 5 mm in the inserted part. A membrane coated with a fluorinated resin filtration membrane having a large number of holes was used. The housing is made of stainless steel, and the inner fitting surface of the fitting portion of the lid member is provided with two bulges as shown in Fig. 1 at positions that divide the inner fitting surface into three equal parts. The bulge had a bulged semicircular shape with a diameter of 1 mm.

After fixing and storing the element manufactured as described above in the housing at room temperature, room temperature gas containing particles and low temperature liquefied gas were alternately flowed, and there was no leakage in the range of -70℃ to 20℃. ,
More than 99.8% of particles with a particle size of 0.2 μm or more could be collected. In addition, the lower the temperature during use of this filter, the better the airtightness between the element and the housing and the stronger the bond. For example, at temperatures immediately after liquefied nitrogen is distributed (approximately -196°C), the element cannot be pulled out manually. It was difficult.

Although one embodiment of the present invention is as described above, the bulges 17a and 17b provided on the inner fitting surface 16a of the fitting part 16 are not limited to two rows, but may be bent due to machining accuracy or bending during fitting. The number may be set as appropriate, taking into account the following. In addition, the bulging portions 17a and 17b are not only formed by machining the inner fitting surface 16a, but also an O-ring made of a material stronger than resin, such as a metal, is attached to the inner fitting surface 16a. It may be provided depending on Next, in the embodiment described above, a groove for attaching an O-ring made of silicone rubber or the like is provided on the outer circumferential surface of the fitting portion 11c, but it may also be provided on the outer fitting surface 16b of the fitting portion 16. Next, the element is not limited to that of the above embodiment, but may be one in which a reinforcing body is covered with a bag-shaped filtration membrane, and the open end of the bag-shaped filtration membrane is thermally welded to the body of the reinforcing body.

[Effect of idea]

In the filter for low-temperature liquefied gas of the present invention, when using a resin-made filtration membrane, the reinforcing body to which the resin-made filtration membrane is attached is made of resin, and there are problems in bonding the two, and the low-temperature liquefied gas piping has a wide temperature range. In addition to solving the problem of thermal expansion associated with being used in wide widths,
The connection between the resin reinforcing body and the metal housing was solved by providing a connecting means on each end face that skillfully utilizes the difference in thermal expansion coefficient between the two, and as a result, the filter of the present invention can withstand temperatures ranging from room temperature to low temperature. It can be stably installed in low-temperature liquefied gas piping that is used over a wide temperature range, and it can remove particles that are smaller than before, making it extremely practical for use in the semiconductor industry, etc.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is an exploded sectional view of a filter for low-temperature liquefied gas, and FIG. 2 is an enlarged sectional view of a fitting portion between a reinforcing body and a lid member. 10...filter, 11...reinforcement body, 11a...
...Body part, 11b...Vent hole, 12...Filtration membrane, 1
3...Element, 14...Housing, 14a
...Main body, 14b...Lid member, 15a, 15b...
...O-ring groove, 16a...Inner fitting surface, 16b
...Outer fitting surface, 17a, 17b...Bulging portion, 1
8a, 18b...O-ring, 19...O-ring.

Claims (1)

[Scope of utility model registration request] An element comprising a resin reinforcement body having a ventilation hole on the outer surface of a bottomed cylindrical body and a fitting part on the open end side and covered with a resin filtration membrane, and a main body and a lid member that house the element. A concentric fitting part is provided on the end face of the lid member, and the element is fixed to the lid member by fitting the fitting part. A filter for low-temperature liquefied gas, characterized in that a bulging part is provided on the fitting surface, and an O-ring is provided between the outer fitting surface of the fitting part and the outer peripheral surface of the fitting part.