Leakage vacuum detection system for magnetic fluid vacuum seal using micro pressure detection sensor module

Abstract

The present invention relates to a leakage vacuum detection system for a magnetic fluid vacuum seal using a micro pressure detection sensor module. Specifically, by installing a micro sensor module in a vacuum seal applied to a product having a limited internal space to accurately measure a pressure difference between an atmospheric side and a vacuum side, the system can detect leakage of a magnetic fluid and enable quick response to the leakage.

Description

Leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module

[0001] The present invention relates to a leakage vacuum detection system of a magnetic fluid vacuum seal, and more particularly, to a leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module installed in a narrow passage of a magnetic fluid vacuum seal to detect a vacuum leak between the atmosphere side and the vacuum side in a vacuum environment.

[0002] The space between two static surfaces with no relative motion can be sealed relatively easily using O-rings, gaskets, etc. However, sealing between two surfaces experiencing relative motion, such as a rotating shaft, requires more considerations and is more difficult than sealing between static surfaces.

[0003] Until now, methods of sealing rotating shafts using mechanical seals, lip seals, etc. have been commonly used. However, these sealing methods have the problem of generating dust due to wear due to solid friction occurring between the rotating shaft and the seal.

[0004] A ferrofluid vacuum seal (also known as a magnetic seal) overcomes these shortcomings by sealing the gap between the rotating shaft and the housing using a magnetic fluid, a fluid that attracts magnets. In other words, it uses permanent magnets to hold the magnetic fluid in place in the gap.

[0005] Ferrofluid vacuum seals based on this principle do not generate solid-state friction, thus producing no dust and boasting a long service life. For these reasons, they are widely used in vacuum chambers for semiconductor processes that require high cleanliness.

[0006] A ferrofluid vacuum seal is generally composed of a permanent magnet, a pole piece, a rotating shaft, ferrofluid, and a housing containing them.

[0007] A number of trenches are formed on the rotating shaft, and the magnetic flux from the N pole of the permanent magnet enters the S pole of the permanent magnet through the teeth of the trench and the pole piece, thereby keeping the magnetic fluid confined between the tip of each trench tooth and the pole piece.

[0008] As mentioned above, these magnetic fluid vacuum seals are widely used in vacuum chambers in semiconductor manufacturing processes that require a clean environment, and are also applied to products with very limited internal space, such as medical devices, wearable devices, smartphones, and drones, where cutting-edge technology is applied. If leakage of the magnetic fluid occurs due to external environmental factors such as temperature, load, shock, and vibration, a pressure difference may occur between the atmospheric side and the vacuum side, which may deteriorate performance.

[0009] In order to take immediate action in the event of a breakdown due to performance degradation, it is necessary to install a pressure detection sensor module and monitor in real time. However, since products that use magnetic fluid vacuum seals have limited internal space, the location suitable for installing a pressure detection sensor module is very narrow, requiring the development of a small-sized sensor module.

[0010] The present invention has been devised to solve the problems of the above-mentioned prior art, and the purpose of the present invention is to provide a leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module, which can quickly take subsequent measures by measuring / detecting a pressure difference between the atmosphere side and the vacuum side due to leakage of magnetic fluid, etc., by installing an ultra-small sensor module in a magnetic fluid vacuum seal applied to a product having a limited internal space.

[0011] In order to solve the above-described problem, the present invention provides a leakage vacuum detection system of a ferrofluid vacuum seal using an ultra-small pressure detection sensor module, comprising: a housing having a rotational shaft for transmitting power from an atmosphere side to a vacuum side and having a flow path formed on one side; a pair of pole pieces forming a space communicating with the flow path while surrounding the rotational shaft in an internal space of the housing and spaced apart from each other by a predetermined distance; a permanent magnet surrounding the rotational shaft in the space; and a ferrofluid restrained between the rotational shaft and the pole pieces by the magnetic force of the permanent magnet; an ultra-small pressure detection sensor module including a PCB inserted into the flow path of the ferrofluid vacuum seal, a pressure sensor and a resistor installed on an upper surface of the PCB, and a capacitor and a transistor installed on a lower surface of the PCB; and a control unit for receiving a pressure value measured by the ultra-small pressure detection sensor module.

[0012] And, a connector is connected to one end of the PCB, and the connector is spirally connected to the inlet portion of the euro.

[0013] Here, silicone is applied to the connection part between the connector and the PCB.

[0014] In addition, a rubber ring is installed at the end of the screw thread formed on the connector, so that when the connector is screw-connected to the inlet portion of the euro, the rubber ring is in close contact with the housing.

[0015] The leakage vacuum detection system of a magnetic fluid vacuum seal using the ultra-small pressure detection sensor module of the present invention configured as described above has the advantage of being easily usable in small products with limited internal space by installing the ultra-small pressure detection sensor module manufactured in a small size inside a small passage communicating with the space formed between a pair of pole pieces.

[0016] Figure 1 is a diagram showing an ultra-small pressure detection sensor module of the present invention.

[0017] Fig. 2 is a drawing showing the ultra-small pressure detection sensor module and connector shown in Fig. 1 connected.

[0018] Figure 3 is a drawing showing an ultra-small pressure detection sensor module of the present invention installed in a magnetic fluid vacuum seal.

[0019] Hereinafter, an embodiment of a leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module according to the present invention will be described in detail with reference to the attached drawings.

[0020] FIG. 1 is a diagram showing an ultra-small pressure detection sensor module of the present invention, FIG. 2 is a diagram showing the ultra-small pressure detection sensor module shown in FIG. 1 and a connector connected, and FIG. 3 is a diagram showing the ultra-small pressure detection sensor module of the present invention installed in a magnetic fluid vacuum seal.

[0021]

[0022] A leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module according to the present invention is configured to include a magnetic fluid vacuum seal (10), an ultra-small pressure detection sensor module (20) installed in the magnetic fluid vacuum seal (10), and a control unit (30) electrically connected to the ultra-small pressure detection sensor module (20).

[0023]

[0024] The above magnetic fluid vacuum seal (10) is used to maintain a vacuum state of a vacuum chamber when transmitting power from the atmosphere side to the vacuum side in a vacuum chamber, and is configured to include a housing (12) that accommodates a rotation shaft (11) for transmitting power from the atmosphere side to the vacuum side, a pair of pole pieces (13) installed inside the housing (12), a permanent magnet (14) installed between the pole pieces (13), and a magnetic fluid (15) restrained between the rotation shaft (11) and the pole pieces (13).

[0025] The above-mentioned rotation shaft (11) penetrates the housing (12) to transmit power from the atmosphere side to the vacuum side. A number of trenches (trench, 11a) are formed on the outer surface of the rotation shaft (11) in the portion surrounded by the pole piece (13).

[0026] The above housing (12) is coupled to the vacuum chamber side while accommodating the rotation shaft (11). A narrow passage (12a) with a diameter of less than 6 mm is formed on one side of the housing (12).

[0027] The above-mentioned pole pieces (13) are installed in two pieces in the internal space of the housing (12), and surround the rotation axis (110) while being spaced apart from each other by a certain distance. Since the two pole pieces (13) are installed at a certain distance apart from each other in this way, a space (13a) that is connected to the flow path (12a) is formed between the pole pieces (13).

[0028] The above permanent magnet (14) surrounds the rotation axis (11) in the space (13a) formed between the pole pieces (13).

[0029] The above magnetic fluid (15) is applied to the teeth of the trench (11a) of the rotation shaft (11), and is held in a ring shape between the rotation shaft (11) and the pole pieces (13) by the magnetic force of the permanent magnet (14).

[0030] Since the magnetic fluid vacuum seal (10) is configured as above, the magnetic flux from the N pole of the permanent magnet (14) enters the S pole of the permanent magnet (14) through the teeth of the trench (11a) of the rotation shaft (11) and the pole piece (13), thereby keeping the magnetic fluid (15) confined between the tip of the teeth of each trench (11a) and the pole piece (13).

[0031]

[0032] The above ultra-small pressure detection sensor module (20) is inserted into the flow path (12a) of the magnetic fluid vacuum seal (10) to measure the pressure difference between the vacuum side and the atmospheric side, and is configured to include a PCB (21), a pressure sensor (22) and a resistor (23) installed on the upper surface of the PCB (21), and a capacitor (24) and a transistor (25) installed on the lower surface of the PCB (21).

[0033] The above PCB (21) is a single PCB based on the Arduino system, eliminating unnecessary circuits, and miniaturizing the width / height to 20.0 / 4.5 mm. By miniaturizing the size of the PCB (21) into a rectangular shape, it can be easily inserted into a 6.0 mm diameter path (12a).

[0034] The above pressure sensor (22) is installed on the upper surface of the PCB (21), and uses Bosch's BMP180 sensor.

[0035] The above resistor (23) is installed on the upper surface of the PCB (21), and two of them are installed next to the pressure sensor (22).

[0036] The above capacitors (24) are installed in three numbers on the bottom surface of the PCB (21) and are used to stabilize voltage, remove noise, and ensure accuracy of sensor output values.

[0037] The above transistor (25) amplifies or switches by controlling the current or voltage flow, and one is installed in the center of the bottom surface of the PCB (21).

[0038]

[0039] Meanwhile, a connector (40) for firmly fixing an ultra-small pressure detection sensor module (20) to a housing (12) is connected and fixed by soldering to one end of the PCB (21).

[0040] The above connector (40) is spirally connected to the inlet portion of the flow path (12a) formed in the housing (12). This connector (40) is composed of a fastening portion (41) having a spiral formed on the outer surface for spirally connecting to the flow path (12a), a nut portion (42) having a diameter larger than the fastening portion (41) and having an outer surface formed at an angle so as to be easily held and turned with a tool such as pliers while being exposed to the outside of the housing (12), and a protrusion (43) provided on the outer surface of the nut portion (42) and exposed to the outside of the housing (12).

[0041] In addition, silicone (50) was applied to the connection portion of the connector (40) and the PCB (21). That is, by surrounding the connection portion (41) of the connector (40) and the connection portion of the PCB (21) with silicone (50), the vacuum tightness of the connector (40) was improved.

[0042] In addition, a rubber ring (60) is installed at the end of the screw thread formed at the fastening portion (41) of the connector (40). That is, the rubber ring (60) is installed at the end of the fastening portion (41) that contacts the nut portion (42). Accordingly, when the connector (40) is screw-connected to the inlet portion of the flow path (12a), the rubber ring (60) is in close contact with the housing (12) at the inlet portion of the flow path (12a), thereby further enhancing the vacuum tightness.

[0043]

[0044] The above control unit (30) receives the pressure value measured by the ultra-small pressure detection sensor module (20).

[0045]

[0046] A leak vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module according to the present invention configured as described above is briefly described as follows.

[0047] In the initial stable state where a passage (12a) communicating with the space (13a) between the pole pieces (13) is formed in the housing (12), and an ultra-small pressure detection sensor module (20) is inserted and fixed in this passage (12a), the magnetic force of the permanent magnet (14) causes the magnetic fluid (15) to maintain a ring shape between the end of the trench (11a) of the rotation shaft (11) and the pole piece (13), thereby maintaining airtightness and preventing a pressure difference between the atmosphere side and the vacuum side.

[0048] If this state is maintained and then subjected to a harsh environment such as temperature or load, the magnetic fluid (15) is damaged and leaks.

[0049] When the magnetic fluid (15) leaks, the sealing performance deteriorates, and the space (13a) between the pole pieces (13), which was at atmospheric pressure, gradually changes to a vacuum state, resulting in a pressure deviation. This pressure deviation is detected by the ultra-small pressure detection sensor module (20) installed in the flow path (12a) of the housing (12), and the control unit (30) transmits this detection signal to issue a warning signal such as an alarm.

Claims

1. A magnetic fluid vacuum seal (10) including a housing (12) that accommodates a rotational shaft (11) for transmitting power from an atmosphere side to a vacuum side and has a flow path (12a) formed on one side, a pair of pole pieces (13) that surround the rotational shaft (11) in the internal space of the housing (12) but form a space (13a) that is spaced apart from the rotational shaft (11) by a certain distance and communicates with the flow path (12a), a permanent magnet (14) that surrounds the rotational shaft (11) in the space (13a), and a magnetic fluid (15) that is restrained between the rotational shaft (11) and the pole pieces (13) by the magnetic force of the permanent magnet (14); An ultra-small pressure detection sensor module (20) including a PCB (21) inserted into the flow path (12a) of the magnetic fluid vacuum seal (10), a pressure sensor (22) and a resistor (23) installed on the upper surface of the PCB (21), and a capacitor (24) and a transistor (25) installed on the lower surface of the PCB (); A leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module, characterized in that it comprises a control unit (30) that receives the pressure value measured by the ultra-small pressure detection sensor module (20).

2. In claim 1, A leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module characterized in that a connector (40) is connected to one end of the PCB (21) and the connector (40) is spirally connected to the inlet portion of the passage (12a).

3. In claim 2, A leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module characterized in that silicone (50) is applied to the connection part of the above connector (40) and PCB (21).

4. In claim 2, A leakage vacuum detection system of a magnetic fluid vacuum seal using an ultra-small pressure detection sensor module, characterized in that a rubber ring (60) is installed at the end of the screw thread formed in the connector (40), and the rubber ring (60) is in close contact with the housing (12) when the connector (40) is spirally connected to the inlet portion of the passage (12a).

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