Patent Application
20100281989
The present invention relates to a pressure sensor, and more particularly, to a pressure sensor sensing or measuring air pressure and a device for preventing air inflow into the pressure sensor, which can prevent air, moisture and foreign substances from flowing into the pressure sensor.
A pressure sensor is a device that measures pressure in a process or a system. The pressure sensor is one of the most widely used sensors, which is applied to a variety of uses such as industrial instrumentation, automatic control, medical service, automatic engine control, environmental control, and electric appliances.
The measuring principle of the pressure sensor uses displacement, deformation, magnetic-thermal heat conductivity, vibrations or the like. Many kinds of pressure sensors are in current use.
Examples of pressure sensors include mechanical pressure sensors using a Bourdon tube, a diaphragm or a bellows, an electronic pressure sensor converting mechanical displacement into an electrical signal, or a semiconductor pressure sensor.
When the measured pressure reaches a specific pressure, the pressure sensor shown in
Referring to
An elastic member 40 in the form of a coil spring is placed on the lower housing 10 to provide an elastic force to the conductive member 50 and the sealing member 60.
A pair of connective members 20 are installed to pass through the lower housing 10. When the conductive member 50 descends against the elastic force of the elastic member 40, the connective members 20 contact the conductive member 50, forming an electrical connection. To make the heights of the connective members 20 uniform, the connective members 20 are exposed above the lower housing 10 through respective protrusions 12 protruding from an upper portion of the lower housing 10.
The sealing member 60 blocks air flow between the upper and lower sides. The upper housing 70 has an air hole 71 to allow the inflow of outside air into a space above the sealing member 60.
The related art pressure sensor may be used to measure air pressure. The operation of the related art pressure sensor will now be described in the case where air is sucked in a vacuum packing device using a vacuum pump, a vacuum processing device, a vacuum chamber or the like.
Referring to
As the air pressure decreases, the sealing member 60 descends, overcoming the elastic force of the elastic member 40. When the pressure of the space reaches a set pressure, the conductive member 50 attached to the bottom of the sealing member 60 contacts the connective members 20 (see
Thus, the pair of connective members 20 are electrically connected together and consequently send an electrical signal to the outside. Based on this electrical signal, the operation of the vacuum pump (not shown) may be stopped.
As described above, the related art pressure sensor may be used to stop the operation of the vacuum pump by sending out an electrical signal when the air pressure of the vacuum line becomes as low as a predetermined pressure or less.
The sealing member 60 ascends again to release the contact between the conductive member 50 and the connective members 20 when outside air is introduced into the vacuum line as the operation of the vacuum pump is stopped after the completion of the vacuum operation or the vacuum operation is not performed (see
At this time, the vacuum line is in communication with the pressure sensor to allow air flow, which may cause moisture, foreign substances and the like to flow into the pressure sensor. This inflow of moisture and the like may occur more often when the vacuum state inside the pressure sensor is suddenly released, causing a rapid inflow of outside air.
Moisture or foreign substances flowing into the pressure sensor interrupt the descent of the sealing member 60 or result in defective contact between the connective members 20 and the conductive member 50. In this case, the pressure sensor completely fails to perform its function.
The limitation of the inflow of moisture or foreign substances to the pressure sensor may also arise with pressure sensors that measure pressure within a predetermined range, as well as the aforementioned pressure sensor reacting to specific pressure as shown in
Also, the above limitation may arise not only with mechanical pressure sensors but also with electrical pressure sensors if those pressure sensors serve to measure the air pressure.
A technique is demanded that can ensure the stable operation of pressure sensors which measure air pressure, by preventing moisture or foreign substances from flowing into the pressure sensor.
The present invention has been made to solve the foregoing problems of the related art and therefore an aspect of the present invention is to provide a pressure sensor capable of preventing moisture or foreign substances from flowing therein when measuring air pressure, and a device for preventing air inflow, which is used in the pressure sensor.
According to an aspect of the present invention, there is provided a pressure sensor including: an air flow part through which air to be measured, the pressure of which is to be measured, flows; a pressure sensing part sensing the pressure of the air to be measured, which flows through the air flow part; and an air blocking part installed between the air flow part and the pressure sensing part, preventing the air to be measured from flowing into the pressure sensing part, and causing, at least, a movement or a deformation according to a pressure change of the air to be measured.
The pressure sensing part may cause, at least, a movement or a deformation by the pressure change of the air to be measured.
The sealed space cut off from the air to be measured may be formed between the pressure sensing part and the air blocking part.
The pressure sensing part may sense that the pressure of the air to be measured reaches a set pressure or lower.
The pressure sensing part may include: a sealing member installed inside a hollow housing; a conductive member having electrical conductivity and attached under the sealing member; and a connective member contacting the conductive member to be electrically connected when the pressure of the air to be measured reaches a set pressure or lower, wherein the sealed space may be formed between one side of the sealing member and the air blocking part.
The pressure sensing part may further include an elastic member providing an elastic force, preventing contact between the conductive member and the connective member when the pressure of the air to be measured is higher than the set pressure, and allowing the conductive member and the connective member to contact each other when the pressure of the air to be measured reaches the set pressure or lower. The pressure sensing part may further include an adjusting member adjusting the elastic force of the elastic member.
The elastic member may be a coil spring or a leaf spring, and the adjusting member may control the amount of deformation of the coil spring or the leaf spring.
The air blocking part may include an air blocking member installed inside a hollow housing to separate the air flow part from the pressure sensing part, and causing, at least, a movement or a deformation according to the pressure change of the air to be measured, and the pressure sensing part may include: a conductive member having electrical conductivity and installed to move together with the air blocking member and a connective member contacting the conductive member to form an electrical connection when the pressure of the air to be measured reaches a set pressure or lower. The conductive member may be fixed by being embedded in a connection shaft protruding upwardly from the air blocking member.
The hollow housing may include an air flow hole to expose the other side of the sealing member to outside air.
The pressure sensing part may measure the pressure of the air to be measured, which flows through the air flow part.
The air blocking part may include: a chamber having one side connected to the air flow part and the other side connected to the pressure sensing part; and an air blocking member installed inside the chamber to separate the air flow part from the pressure sensing part.
The air blocking member may be configured as a film member deformed by the pressure of the air to be measured, which flows through the air flow part.
The film member may have an outer edge fixed to an inner surface of the chamber and a central portion deformed by the pressure of the air to be measured.
The film member may have the outer edge insertedly fixed to a groove or a protrusion formed on the inner surface of the chamber. Alternatively, the film member may have the outer edge bonded and fixed to the inner surface of the chamber.
The air blocking member may be configured as a piston member moved along an inner surface of the chamber by the pressure of the air to be measured, which flows through the air flow part. A stopper may be formed on the inner surface of the chamber to restrict the movement of the piston member.
The film member may be formed of a more flexible material than that of the sealing member.
The film member may be deformed more sensitively to pressure changes of the air to be measured than the sealing member.
The pressure sensing part and the air blocking part may be formed as separate members and connected to each other by a connection tube.
The pressure sensing part and the air blocking part may be stacked inside a casing forming one interior space as a whole.
According to another aspect of the present invention, there is provided an air blocking device of a pressure sensor, the air blocking device including: a chamber having one side connected to an air flow part through which the air to be measured flows, and the other side connected to a pressure sensor measuring the pressure of the air to be measured; and an air blocking member installed inside the chamber to separate the air flow part from the chamber.
The air blocking member may be configured as a film member deformed by the pressure of the air to be measured, which flows through the air flow part. The film member may have an outer edge fixed to an inner surface of the chamber and a central portion deformed by the pressure of the air to be measured.
The air blocking member may be configured as a piston member moved along an inner surface of the chamber by the pressure of the air to be measured, which flows through the air flow part.
According to exemplary embodiments of the present invention, a sealed space formed between a pressure sensing part and an air blocking part due to the air blocking part prevents outside air from flowing into the sealed space, or the air blocking part prevents an air flow from the pressure sensing part. Accordingly, moisture and foreign substances are prevented from flowing into the pressure sensing part of a pressure sensor, thereby minimizing defects in the pressure sensor.
According to the present invention, the air blocking part is formed with simple construction, thereby reducing the need for the repair and replacement of the pressure sensor.
Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to accompanying drawings.
As shown in
The air flow part 110 is connected to a tube (i.e., a vacuum line) through which the air to be measured, the pressure of which is to be measured, flows.
The pressure sensing part 200 includes a sealing member 220 installed inside a hollow housing 210, a conductive member 230 having electrical conductivity and attached under the sealing member 220 through a protrusion 222, and a pair of connective members 240 installed penetrating a lower housing 212 to contact the conductive member 230 to be electrically connected when the pressure of the air to be measured reaches a set pressure or less.
The sealing member 220 may be formed of a flexible material that easily deforms, such as rubber. However, the material of the sealing member 220 is not limited, provided that a sealed space can be formed under the sealing member 220. Also, the sealing member 220 may be formed of multiple materials. For example, different materials may be used for central and circumferential portions of the sealing member 220.
An elastic member 250 may be installed. The elastic member 250 provides an elastic force that prevents contact between the conductive member 230 and the connective members 240 when the pressure of the air to be measured is higher than a set pressure, and forces the conductive member 230 to contact the connective members 240 when the pressure of the air to be measured is as low as the set pressure or lower.
The elastic member 250 may be installed on a lower housing 212, but may be installed, connected to an adjusting member 260 if the adjusting member 260 is installed as will be described below.
The pressure sensing part 200 may include the adjusting member 260 that can adjust the set pressure to which the pressure sensor 100 reacts by controlling the elastic force of the elastic member 250. The adjusting member 260 may be threaded on a central portion of the lower housing 212. The adjusting member 260 is rotated to descend and ascend, thereby controlling the elastic force of the elastic member 250. This is advantageous in that the pressure to which the pressure sensing part 200 reacts can be controlled.
As shown in
An air flow hole 215 may be formed in the upper housing 211 of the hollow housing 210 to expose an upper portion above the sealing member 220 to outside air. The air flow hole 215 prevents the formation of a vacuum space above the sealing member 220 when the sealing member 220 descends, thereby securing smooth movement of the sealing member 220.
The air blocking part 300 may include a chamber 310 having one side connected to the air flow part 110 and the other side connected to the pressure sensing part 200, and an air blocking member 320 installed in the chamber 310 to separate the air flow part 110 from the pressure sensing part 200.
Exemplary embodiments of the air blocking part 300 will now be described with reference to
As described above, the air blocking part 300 includes a chamber 310 having one side 311 connected to the air flow part 110 and the other side 312 connected to the pressure sensing part 200, and an air blocking member 320 installed inside the chamber 310 to separate the air flow part 110 and the pressure sensing part 200 from each other.
As shown in
The film member 330 may have an outer edge 331 fixed to an inner surface of the chamber 310, and a central portion deformed by the pressure of the air to be measured.
As shown in
The film member 330 is deformed when the air flows through the air flow part 110. For example, when the air is sucked through the air flow part 110 due to the operation of a vacuum pump, the film member 330 is curved toward the air flow part 110.
As shown in
That is, the piston member 340 may be configured to slide toward the air flow part 110 when air is sucked through the air flow part 110 by the operation of a vacuum pump or the like. In this case, a stopper 345 or a guide may be formed on the inner surface of the chamber 310 to restrict the movement of the piston member 340. The location of the stopper 345 or the guide is adjustable according to the design pressure.
A sealed space 150 is formed between one side of the sealing member 220 and the air blocking part 300.
The sealed space 150 prevents an inflow of outside air through the air flow hole 215 or an inflow of the air to be measured through the air flow part 110. The sealed space 150 holds air of a predetermined volume.
The sealed space 150 holding the predetermined volume of air causes movement of the sealing member 220 due to the air blocking member 320 deforming or moving.
For example, when the air blocking member 320 deforms toward the air inflow side, the sealing member 220 moves in the same direction in which the air blocking member 320 deforms because the sealed space 150 contains air of the same volume and thus maintains a constant air pressure.
That is, the sealed space 150 is designed to maintain a constant air pressure (volume).
Thus, the sealing member 220 of the pressure sensing part 200 moves according to a pressure change of the air to be measured, so that the conductive member 230 contacts the connective members 240.
To allow the sealing member 220 to be smoothly moved by the deformation or movement of the air blocking member 320, the air blocking member 320 configured as the film member 330 or the like may be deformed more sensitively to the pressure change of the air to be measured, than the sealing member 220.
To this end, the film member 330 may be formed of a more flexible material than that of the sealing member 220. The material of the film member 330 is not limited, provided that it can easily deform according to changes in air pressure. Exemplary materials of the film member 330 may include rubber and a thin synthetic resin such as vinyl.
A pressure sensor according to another exemplary embodiment of the present invention will now be described with reference to
In the pressure sensor 100 of
Like reference numerals in the drawings denote like elements, and to avoid unnecessary repetition of the description, only dissimilar parts to the embodiment of
As shown in
For the installation of the elastic member 250, a support member 270 may be installed in the sealed space 150. The support member 270 may have a hole for air flow within the sealed space 150.
In the pressure sensor of
The operational effects of the pressure sensor measuring the air pressure according to the above exemplary embodiments will now be described using the case of vacuum processing as an example.
Referring to
A sealed space formed between the air blocking member 320 and the sealing member 220 has a tendency to maintain a constant volume or pressure. For this reason, the sealing member 220 descends to cope with the deformation of the air blocking member 320.
As the pressure of the air is further decreased, the air blocking member 320 deforms more, and thus the sealing member 220 descends more. When the air to be measured reaches a set pressure, the conductive member 230 comes into contact with the connective members 240 as shown in
As described above, the air pressure is measured indirectly through the sealed space 150 without a direct inflow of the air to be measured to the pressure sensing part 200. Thus, moisture or foreign substances can be completely prevented from flowing into the pressure sensing part 200.
The pressure sensing part 200 has been described above as having a configuration to sense whether the pressure of the air to be measured, which flows through the air flow part 110, reaches a set pressure or lower. However, the pressure sensing part 200 may have a configuration to measure the pressure of the air to be measured. For example, the pressure sensing part 200 may have a configuration to measure a pressure value within a predetermined range, such as a general pressure sensor or a pressure gauge.
As shown in
Alternatively, as shown in
As shown in
That is, referring to
Such an air blocking device has the same construction as the air blocking part 300 described with reference to
A pressure sensor according to another exemplary embodiment of the present invention will now be described with reference to
Like reference numerals in the drawings denote like elements, and to avoid unnecessary repetition of the description, only dissimilar parts to the embodiments of
Referring to
The air flow part 110, the pressure sensing part 200 and the air blocking part 300 may be installed inside a hollow housing 210 including an upper housing 211, a middle housing 213, and a lower housing 212 to form a space with a predetermined size therein. The air flow part 110 may be installed to be connected to, e.g., the lower housing 212.
In the space inside the hollow housing 210, the air blocking part 300 is installed between the air flow part 110 and the pressure sensing part 200. The air blocking part 300 serves to block inflow of the air to be measured from the air flow part 110 to the pressure sensing part 200.
The air blocking part 300 includes an air blocking member 320 separating the air flow part 110 from the pressure sensing part 200. The air blocking member 320 moves according to the pressure change of the air to be measured from the air flow part 110.
As described with reference to
The pressure sensing part 200 may include a conductive member 230 and connective members 240. The conductive member 230 has electrical conductivity and is installed to move with air blocking member 320. The connective members 240, when the pressure of the air to be measured reaches a set pressure or lower, contacts the conductive member 230 to be electrically connected thereto.
The conductive member 230 is inserted and fixed to a groove 321a formed in a connection shaft 321 protruding upwardly from the air blocking member 320, so that the conductive member 230 moves together with the air blocking member 320. As shown in
The air blocking part 300 installed in the pressure sensor 100a of
The air blocking part 300 may further include an adjusting member 380 to control the elastic force of the elastic member 370. The adjusting member 380 rotates along a screw thread formed on the lower housing 212, thereby controlling the pressing force of the elastic member 320 pressing the air blocking member 320. However, a method for the adjusting member 380 to control the pressing force of the elastic member 370 is not limited to the description. The adjusting member 380 can control the conductive member 230 to contact the connective member 240 at a specific pressure when the conductive member 230 is moved by the movement of the air blocking member 320, so that the pressure sensing part 200 can be controlled to sense the specific pressure.
The operational effects of the pressure sensor 100a of
As shown in
As the pressure of the air to be measured keeps decreasing, the air blocking member 320 deforms further toward its lower side, and thus the conductive member 230 descends further. When the air to be measured is at a set pressure, the conductive member 230 contacts the connective members 240 as shown in
Since the air to be measured does not flow directly through the pressure sensing part 200, moisture or foreign substances can be completely prevented from flowing into the pressure sensing part 200.
While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1020080005940 | Jan 2008 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR08/06928 | 11/24/2008 | WO | 00 | 7/13/2010 |
