Connection of a copper capillary tube with a synthetic capillary tube

Abstract

In the newly invented connection, the copper capillary tube (1) is inserted into and soldered with a copper tube (2). Thus, a soldered connection is created (3). The copper tube (2) has a rib (4) at its non-soldered end, and the flared end of the synthetic capillary tube (5) is inserted into the copper tube (2) up to the rib (4). The space between the synthetic capillary tube (5) and the copper tube (2) holds at least one O-ring (6) fitted to suit the synthetic capillary tube (5) and the copper tube (2), and the non-soldered end of the copper tube (2) has a closing rib (7).

Description

[0001] Connection of a copper capillary tube with a synthetic capillary tube

[0002] The subject matter of the invention is a connection of a copper capillary tube with a synthetic capillary tube.

[0003] In the existing solution, the connection of a copper capillary tube with a synthetic capillary tube is realised through a flared-end synthetic capillary tube having been pulled over a copper capillary tube and clamped over it with another copper tube pulled over the connection. The synthetic capillary tube needs to be expanded and mechanically pulled over the copper capillary tube. Next, a copper tube (clamp) is pulled over the connection to hold it in place. Owing to the inaccuracy of the copper capillary tube’s edges after cutting and the unevenness of the internal surface of the flared part of the synthetic capillary tube, the connection may be leaky. Moreover, the pulling of the clamp is made in one direction, therefore, the clamp may slide off in the opposite direction and break the connection.

[0004] The solution in use hitherto is unreliable, insufficiently tight and does not allow for any type of movement between the capillary tubes. Moreover, it is difficult to be performed, and its manufacturing is time-consuming. The expansion of a synthetic capillary tube to a size which allows it to be pulled over a copper capillary tube over a stretch of at least 5 mm is very difficult to be achieved.

[0005] The performance of a connection through the clamping of a synthetic capillary tube over a copper capillary tube is difficult due to hardness of the synthetic capillary tube. Moreover, considering that the tubes are clamped in one direction only, the connection is not secure in the event the synthetic capillary tube is pulled with a considerable force. As a result, the existing solution is in practice unreliable.

[0006] In order to eliminate the problem, an innovative connection of a copper capillary tube with a synthetic capillary tube has been invented.

[0007] The copper capillary tube is inserted into and soldered with a copper tube. Thus, a soldered connection is created. The copper tube (2) has a rib (4) at its non-soldered end, and the flared end of the synthetic capillaiy tube (5) is inserted into the copper tube (2) up to the rib (4). The space between the synthetic capillary tube (5) and the copper tube (2) holds at least one Ciring (6) fitted to suit the synthetic capillary tube (5) and the copper tube (2), and the nonsoldered end of the copper tube (2) has a closing rib (7).

[0008] Preferably, a section of 20-30 mm of the copper capillary tube is inserted into the copper tube. Preferably, the copper tube has a rib at a distance of 18-25 mm from its non-soldered end.

[0009] Preferably, the closing rib is at a distance of 5-10 mm from the non-soldered end of the copper tube.

[0010] The subject matter of the invention is a connection of two capillary tubes made of different materials: copper and a synthetic material. The connection is realised by way of a copper tube - a connector of the two capillary tubes, and appropriate actions, such as: tight soldering of the copper capillary tube with the copper tube, the performance of an appropriate rib, the insertion of the flared end of the capillary tube into the copper tube, the placement of O- rings of appropriate sizes and made of compatible materials, and the performance of a rib closing the connection.

[0011] Both ribs are aimed to narrow the cross-section of the copper rib in their respective locations. They must be made in a way to prevent the inserting or pulling out of the flared end of the synthetic capillary tube into / from the connection and not to clamp the capillary tube (clamping of the capillary tube may narrow its internal cross-section or even close the tube).

[0012] The O-rings are aimed to keep the connection tight. At least one O-ring must be used. The O-rings must be made of materials of high thermal and chemical resistance withstanding the operating conditions in which the connection is performed, and have a size ensuring tightness of the connection. The O-ring must fit into the connection and ensure its tightness; e.g., for a synthetic capillary tube of the external diameter of 2.1 mm and a copper tube of the internal diameter of 3 mm, O-rings of a size of 2x0.7 mm, made of NBR resistant to the cooling agent (since the connection is intended to be used in cooling systems) and the temperature prevailing in the system, have been selected. The selection of materials of the synthetic capillary tube and the O-ring is of key importance for the connection to withstand certain temperatures and chemical conditions.

[0013] The connection according to the invention allows for a slight axial movement and a rotary movement of the capillary tube. The solution eliminates the unnecessary stress caused by the connection of two capillary tubes in order to obtain a tight connection.

[0014] The connection of a copper capillary tube with a synthetic capillary tube according to the invention can be applied in any system where there is a need to use two capillary tubes made of different materials whose connection, e.g. through soldering, welding, or gluing (pneumatic or hydraulic systems) is difficult to be performed. At the same time, it is suitable for use in systems where a connection resistant to the exposure to extreme temperatures or chemical agents, which may compromise its reliability, is required. The connection of a copper capillary tube with a synthetic capillary tube performed according to the invention is shown in the picture below, in a sectional view.

[0015] Example 1

[0016] A 30-mm section of the copper capillary tube 1 is inserted into the copper tube 2 and soldered, creating a soldered connection 3. At a distance of 18 mm from its non-soldered end, the copper tube 2 has a rib 4 which narrows its cross-section. The flared end of the synthetic capillary tube 5 is inserted into the copper tube 2 up to the point at which it stops at the rib 4. The space between the synthetic capillary tube 5 and the copper tube 2 holds one O-ring 6 fitted to suit the synthetic capillary tube 5 and the copper tube 2. At a distance of 6 mm from its nonsoldered end, the copper tube 2 has a rib 7 which narrows the cross-section of the copper tube 2 and closes the connection.

[0017] Example 2

[0018] A 20-mm section of the copper capillary tube 1 is inserted into the copper tube 2 and soldered, creating a soldered connection 3. At a distance of 25 mm from its non-soldered end, the copper tube 2 has a rib 4 which narrows its cross-section. The flared end of the synthetic capillary tube 5 is inserted into the copper tube 2 up to the point at which it stops at the rib 4. The space between the synthetic capillary tube 5 and the copper tube 2 holds two O-rings 6 fitted to suit the synthetic capillary tube 5 and the copper tube 2. At a distance of 10 mm from its nonsoldered end, the copper tube 2 has a rib 7 which narrows the cross-section of the copper tube 2 and closes the connection.

Claims

Claims1. The copper capillaiy tube (1) is inserted into and soldered with a copper tube (2). Thus, a soldered connection is created (3). The copper tube (2) has a rib (4) at its non-soldered end, and the flared end of the synthetic capillary tube (5) is inserted into the copper tube (2) up to the rib (4). The space between the synthetic capillary tube (5) and the copper tube (2) holds at least one O-ring (6) fitted to suit the synthetic capillary tube (5) and the copper tube (2), and the non-soldered end of the copper tube (2) has a closing rib (7).

2. The copper of claim 1, wherein a section of 20-30 mm of the copper capillary tube (1) is inserted into the copper tube (2).

3. The copper of claim 1 or 2, wherein the copper tube (2) has a rib (4) at a distance of 18- 25 mm from its non-soldered end.

4. The copper of claim 1 or 2 or 3, wherein the closing rib (7) is at a distance of 5-10 mm from the non-soldered end of the copper tube (2).

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