Absolute pressure transducer having improved operating temperature range - Patents.com

Abstract

An exemplary pressure transducer is disclosed that includes an absolute pressure sensor including a fluid input and configured to output a signal representative of the pressure sensed at the fluid input, and an outer insulating housing around the absolute pressure sensor, where a space between the housing and the absolute pressure sensor contains a vacuum pressure.

Description

[Technical field]

[0001] Field of Disclosure The present disclosure relates generally to pressure transducers, and more particularly to absolute pressure transducers having an improved operating temperature range. [Background technology]

[0002] background Absolute pressure sensors, or absolute pressure transducers, measure the pressure of a fluid input to the sensor in a manner that is not affected by the surrounding (e.g., atmospheric) pressure. Absolute pressure sensors are used, for example, in process control systems or other systems where it is desirable to measure the pressure of a space. Summary of the Invention

[0003] overview An absolute pressure transducer having an improved operating temperature range is disclosed substantially as illustrated by and described with reference to at least one of the drawings and as more fully set forth in the claims.

[0004] BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read in conjunction with the accompanying drawings, in which like reference characters represent like parts throughout. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a block diagram of an example process control system including an absolute pressure sensor in accordance with an aspect of the present disclosure.

[0006] [Diagram 2] 2 is a schematic diagram of an example absolute pressure sensor that may be used to implement the absolute pressure sensor of FIG. 1 according to an embodiment of the present disclosure.

[0007] [Diagram 3] 3 is a flow diagram depicting an example method that may be performed to assemble the example absolute pressure sensor of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The drawings are not necessarily to scale and where appropriate, similar or identical reference numbers are used to indicate similar or identical elements.

[0009] Detailed Description For the purposes of promoting an understanding of the principles of the claimed technology and setting out the best currently understood modes of operation, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same, however, this is not intended to limit the scope of the claimed technology, and it is to be understood that such changes and further modifications in the devices shown, and such further applications of the principles of the claimed technology shown therein, are believed to be ordinarily contemplated by one of ordinary skill in the art to which the claimed technology pertains.

[0010] Some conventional absolute pressure sensors are heated to match or exceed the temperature of the space or fluid being measured. However, the proximity of the thermal circuitry of the conventional absolute pressure sensor to the measurement instrument may limit the temperature range of the conventional absolute pressure sensor. Some conventional absolute pressure sensors include insulation disposed between the sensor core and the exterior of the sensor and / or between the sensor core and the electronic circuitry. However, the inclusion of insulation may result in undesirable particle contamination in the manufacturing area around the absolute pressure sensor.

[0011] In contrast to conventional absolute pressure sensors, the disclosed exemplary pressure transducers can accommodate higher input fluid temperatures with reduced overall size or volume. The disclosed exemplary pressure transducers provide high thermal impedance vacuum insulation between the pressure sensor portion of the pressure transducer and other components, such as sensing circuitry and / or communication circuitry. The disclosed examples are compatible with conventional sensing cores and provide an extended operating temperature range. In particular, the disclosed exemplary pressure transducers eliminate insulation that can introduce undesirable materials into the surrounding manufacturing area and / or reduce the energy involved in heating the sensor core to a desired temperature due to reduced heat loss.

[0012] As used herein, the term "fluid" includes both liquid and gaseous substances.

[0013] An exemplary pressure transducer is disclosed that includes an absolute pressure sensor having a fluid input and configured to output a signal representative of the pressure sensed at the fluid input, and an outer insulating housing around the absolute pressure sensor, where a space between the housing and the absolute pressure sensor contains a vacuum pressure.

[0014] In some exemplary pressure transducers, the absolute pressure sensor includes a capacitance manometer that includes an interior space having a vacuum pressure, In some exemplary pressure transducers, the space between the housing and the capacitance manometer is not in fluid communication with the interior space of the capacitance manometer.

[0015] In some exemplary pressure transducers, the absolute pressure sensor includes one or more inner signal ports configured to output a pressure signal from within the absolute pressure sensor, and the outer insulating housing includes one or more outer signal ports coupled to the one or more inner signal ports, the outer signal ports configured to transmit the pressure signal to the exterior of the outer insulating housing. Some such pressure transducers further include sensing circuitry coupled to the one or more outer signal ports. In some such exemplary pressure transducers, the sensing circuitry is mounted on a circuit board that is mounted to the outer insulating housing. In some such pressure transducers, the outer insulating housing and vacuum insulate the circuit board and the sensing circuitry from the elevated temperatures in the absolute pressure sensor.

[0016] In some exemplary pressure transducers, the temperature of the fluid input is greater than 160° C., greater than 200° C., or greater than 250° C. Some exemplary pressure transducers further include a heater within the space configured to heat the absolute pressure sensor, and the outer insulating housing includes a heater power port coupled to the heater and configured to transmit power to the heater from outside the outer insulating housing. In some such examples, the outer insulating housing includes a heater control port coupled to the heater and configured to transmit at least one of a control signal or a temperature measurement signal between the outside of the outer insulating housing and the heater.

[0017] Some exemplary pressure transducers further include a fluid input tube coupled to the absolute pressure sensor and the outer insulating housing, the fluid input tube configured to deliver fluid to the fluid input. In some exemplary pressure transducers, the fluid input tube and the outer insulating housing seal a space. In some exemplary pressure transducers, the fluid input tube and the outer insulating housing are at least one of brazed, welded, or integrally constructed.

[0018] In some exemplary pressure transducers, the outer insulating housing includes at least one of stainless steel, aluminum, Hastelloy™ alloy, Inconel™ alloy, or glass. In some exemplary pressure transducers, the outer insulating housing includes a pinch tube. In some exemplary pressure transducers, the vacuum pressure between the housing and the absolute pressure sensor is less than atmospheric pressure. In some exemplary pressure transducers, the vacuum pressure between the housing and the absolute pressure sensor is less than 100 Torr (about 13.3 kPa), less than 1 Torr (about 133 Pa), or less than 0.001 Torr (about 0.133 Pa).

[0019] Figure 1 is a block diagram of an example process control system 100 that includes an absolute pressure transducer 102. The example process control system 100 of Figure 1 includes a process chamber 104 to which the absolute pressure transducer 102 is fluidly coupled via a fluid input line 106 to measure the pressure of the process chamber 104.

[0020] The exemplary process chamber 104 can receive one or more inputs, such as process feed materials, via a corresponding number of supply lines 108a, 108b, which can be controlled via mass flow controllers 110a, 110b.

[0021] The exemplary system 100 may include a vacuum pump 112 or other pressure controlled pump, and a valve 114 for controlling flow between the vacuum pump 112 and the process chamber 104. The valve 114 may be controlled by a controller 116, a computing device, and / or any other control technique to maintain the pressure in the process chamber 104 within a desired range. The exemplary absolute pressure transducer 102 is communicatively coupled to the controller 116 to provide pressure feedback to the controller 116 (e.g., for use in a pressure control loop). For example, as the pressure in the process chamber 104 increases, the absolute pressure transducer 102 measures the pressure and provides a signal representative of the pressure to the controller 116, which then controls the valve 114 to increase the flow from the process chamber 104 to the vacuum pump 112. The vacuum pump 112 may have an output to any suitable location based on the nature of the process.

[0022] In contrast to conventional process control systems, the example process control system 100 is capable of accurately measuring the pressure of the process chamber 104 using the absolute pressure transducer 102 at process temperatures (e.g., temperatures of the fluid(s) in the process chamber 104) greater than 160° C., greater than 200° C., greater than 250° C., and / or up to about 850° C. Additionally, the example process control system 100 may require less power to heat the absolute pressure transducer 102 to a given temperature. The example absolute pressure transducer 102 may provide an extended process temperature range in a smaller overall volume than conventional sensors that use thermal insulation.

[0023] Figure 2 is a schematic diagram of an example absolute pressure sensor 200 that may be used to implement the absolute pressure transducer 102 of Figure 1. The example absolute pressure sensor 200 receives a fluid via a fluid input line 204 (e.g., fluid input line 106 of Figure 1), measures the absolute pressure of the received fluid, and outputs one or more signals representative of the measured pressure.

[0024] The exemplary absolute pressure transducer 200 includes an absolute pressure sensor 206 attached to a fluid input line 204. The absolute pressure sensor 206 may also be referred to as a "sensor core" in that the absolute pressure sensor 206 performs measurements that are converted to an output signal. The absolute pressure sensor 206 is at least partially surrounded by an outer insulating housing 208 such that a space 210 exists between the absolute pressure sensor 206 and the outer insulating housing 208. A vacuum pressure is provided in the space 210 to insulate the absolute pressure sensor 206 from the outer insulating housing 208. In some examples, the vacuum pressure in the space 210 is a pressure below atmospheric pressure (e.g., less than 760 Torr (approximately 101 kPa)). The insulation provided by the space 210 improves as the pressure decreases. In some such examples, the vacuum pressure in the space 210 is less than 100 Torr (approximately 13.3 kPa). The vacuum pressure may be as low as less than 1 Torr (about 133 Pa), and is advantageously less than 0.001 Torr (about 0.133 Pa).

[0025] The exemplary outer insulating housing 208 is stainless steel, however, the outer insulating housing 208 may be constructed using aluminum, Hastelloy™ alloy, Inconel™ alloy, glass, and / or any other material capable of being sealed to maintain a vacuum pressure.

[0026] In the illustrated example, the absolute pressure sensor 206 is a capacitance manometer with a flexible diaphragm coupled to an electrode. As the pressure in the fluid input line 204 changes relative to a reference pressure (e.g., a vacuum pressure that may be the same as or different from the vacuum pressure in the space 210), the diaphragm moves, changing the capacitance at the electrode in an amount proportional to the pressure in the input fluid line 204. A capacitance signal is output from the absolute pressure sensor 206 via one or more inner signal ports 212, which are coupled through the space 210 to outer signal ports 214 on the outer insulating housing 208.

[0027] The exemplary absolute pressure sensor 206 has one or more sensor housings 216 that contain a reference pressure and a process fluid. In the example of Figure 2, the space 210 is not in fluid communication with the reference vacuum pressure inside the capacitance manometer. The space 210 is sealed from the fluid input line 204 and from the interior of the absolute pressure sensor 206. For example, the outer insulating housing 208 may be welded, brazed, or otherwise sealed to the fluid input line 204 and / or the sensor housing 216 to provide a seal.

[0028] In a similar manner, inner signal port 212 may extend through one or more of sensor housings 216 and is sealed to sensor housing 216 to maintain a reference pressure within absolute pressure sensor 206. Similarly, outer signal port 214 extends through outer insulating housing 208 and is sealed to outer insulating housing 208 to maintain a vacuum pressure in space 210. Inner signal port 212 and outer signal port 214 transmit one or more measurement signals (e.g., signals representative of the measured pressures) and zero or more reference signals (e.g., signals representative of the measured reference signals, such as for reducing or eliminating common mode errors present in one or more measurement signals).

[0029] The absolute pressure transducer 200 further includes one or more heaters 218 to increase the temperature of the absolute pressure sensor 206 (e.g., to reduce effects caused by thermal gradients between components of the absolute pressure sensor 206 and the process fluid(s). An exemplary heater 218 may be disposed within the volume 210 such that there is an annular space between the heater 218 and the outer insulating housing 208. In some examples, the heater(s) 218 ​​are controlled to heat the absolute pressure sensor 206 to a set temperature, which in some cases is at least an expected process temperature. In some examples, one or more heat spreaders 220 are disposed in contact with the heater(s) 218 ​​and the sensor housing 216 to more effectively distribute heat over a larger area of ​​the absolute pressure sensor 206 and reduce thermal gradients.

[0030] To provide power to the heater 218, the absolute pressure transducer 200 includes heater power port(s) 222 that transmit power through the outer insulating housing 208 and through the space 210 to the heater 218. The example transducer 200 may further include heater control port(s) 224 that can transmit a temperature feedback signal from the heater 218 and / or a temperature sensor 230 on the sensor housing 216 and / or provide a control signal to a heater controller 234 that controls the heat generated by the heater 218.

[0031] The exemplary absolute pressure transducer 200 further includes a sensing circuitry 226 connected to the outer signal port 214 to receive the measurement signal(s) and / or the reference signal(s). The sensing circuitry 226 may correct the measurement signal(s) (e.g., for errors detected via the reference signal(s)). The corrected measurement signal(s) representative of the absolute pressure measured at the absolute pressure sensor 206 may then be transmitted by the sensing circuitry 226 via a communication port 236 (e.g., a connector) (e.g., to the controller 116 of FIG. 1, to another control device and / or data collection device, etc.). In the example of FIG. 2, the exemplary sensing circuitry 226 is mounted within the absolute pressure transducer 200 on a circuit board 228. The outer insulating housing 208 and the vacuum pressure within the space 110 cooperate to insulate the circuit board 228, the sensing circuitry 226, the communication circuitry and / or connector, and / or any other components outside the outer insulating housing 208 from the heat within the outer insulating housing 208.

[0032] To maintain a vacuum in the space 210, the exemplary outer insulating housing 208 includes a pinch tube 232 (or pinch-off tube) that is in fluid communication with the space 210. During manufacture of the outer insulating housing 208 and after sealing, a vacuum is drawn in the space 210 through the pinch tube 232, which is pinched to seal the space 210 when a desired vacuum level is reached.

[0033] Figure 3 is a flow diagram depicting an example method 300 that may be performed to fabricate the example absolute pressure sensor 200 of Figure 2. Although the example manufacturing method is described with reference to Figure 3, other methods may be used, such as additive manufacturing and / or other techniques that reduce the number of bonding operations that need to be performed.

[0034] At block 302, the pressure sensor 206, the fluid input line 204, and the heater 218 are assembled.

[0035] In block 304, a vacuum pressure is induced in the pressure sensor 206 (eg, in a capacitance manometer).

[0036] At block 306, the absolute pressure sensor 206 is inserted into the outer insulating housing 208. The insertion results in the presence of a space 210 between the absolute pressure sensor 206 and the outer insulating housing 208.

[0037] At block 308, the inner signal port 212 is connected to the outer signal port 214 (e.g., on a lid portion of the outer insulating housing 208) and the heater power port(s) 222 are connected to the heater(s) 218. In some examples, the heater control port(s) 224 connects the heater circuitry 234 to a temperature sensor 230 on the absolute pressure sensor 206.

[0038] At block 310, an end(s) (e.g., a lid) is assembled onto the outer insulating housing 208 and the end is sealed onto the outer insulating housing 208. In other examples, any section of the outer insulating housing 208 may be assembled and sealed to form a sealed closed volume 210 around the absolute pressure sensor 206.

[0039] At block 312, the outer insulating housing 208 is sealed to the fluid input line 106. For example, sealing may include welding, brazing, and / or any other sealing method.

[0040] At block 314, a vacuum pressure is induced in the space 210 (e.g., via the pinch tube 232) and once the desired pressure is achieved, the pinch tube 232 is closed or sealed. The example method 300 may then end, or other manufacturing steps may be performed (e.g., mounting and connecting the sensing circuitry 226 and the circuit board 228, encasing the manufactured assembly, etc.).

[0041] As used herein, "and / or" means any one or more of the items in the list linked by "and / or". As an example, "x and / or y" means any element of the three-element set {(x),(y),(x,y)}. In other words, "x and / or y" means "one or both of x and y". As another example, "x, y and / or z" means any element of the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}. In other words, "x, y and / or z" means "one or more of x, y and z". As used herein, the term "exemplary" means to serve as a non-limiting example, instance or illustration. As used herein, the term "for example" begins a list of one or more non-limiting examples, instances or illustrations.

[0042] Although the method and / or system have been described with reference to certain specific embodiments, those skilled in the art will recognize that various modifications and equivalents may be substituted without departing from the scope of the method and / or system. For example, blocks and / or components of the disclosed examples may be combined, divided, rearranged, and / or otherwise modified. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope of the disclosure. Thus, the method and / or system is not limited to the particular embodiments disclosed. Instead, the method and / or system includes all embodiments falling within the scope of the appended claims, both literally and under the doctrine of equivalents.

Claims

1. A pressure transducer comprising: an absolute pressure sensor including a fluid input and a sensor housing configured to accommodate a reference pressure, the absolute pressure sensor configured to output a signal representative of the pressure sensed at the fluid input; an outer insulating housing around the sensor housing of the absolute pressure sensor, wherein a space between the outer insulating housing and the sensor housing contains a vacuum pressure; Equipped with the outer insulating housing includes a pinch tube configured to allow a vacuum pressure to be created in the space when the outer insulating housing is assembled to form the space, and to seal the vacuum pressure in the space when the pinch tube is sealed. Pressure transducer.

2. The pressure transducer of claim 1 , wherein the absolute pressure sensor comprises a capacitance manometer including an interior space, the interior space having a vacuum pressure.

3. 3. The pressure transducer of claim 2, wherein the space between the housing and the capacitance manometer is not in fluid communication with the interior space of the capacitance manometer.

4. 2. The pressure transducer of claim 1, wherein the absolute pressure sensor includes one or more internal signal ports configured to output a pressure signal from within the absolute pressure sensor, and the outer insulating housing includes one or more external signal ports coupled to the one or more internal signal ports, the external signal ports configured to transmit the pressure signal to an exterior of the outer insulating housing.

5. The pressure transducer of claim 4 further comprising sensing circuitry coupled to the one or more external signal ports.

6. 6. The pressure transducer of claim 5, wherein the sensing circuitry is mounted on a circuit board mounted to the outer insulating housing.

7. 7. The pressure transducer of claim 6, wherein the outer insulating housing and the vacuum pressure insulate the circuit board and the sensing circuitry from elevated temperatures in the absolute pressure sensor.

8. The pressure transducer of claim 1 , wherein the temperature of the fluid input is greater than 160° C.

9. The pressure transducer of claim 1 , wherein the temperature of the fluid input is greater than 200° C.

10. 10. The pressure transducer of claim 1, wherein the temperature of the fluid input is greater than 250 degrees Celsius.

11. 10. The pressure transducer of claim 1, further comprising a heater within the space configured to heat the absolute pressure sensor, the outer insulating housing including a heater power port coupled to the heater and configured to transfer power to the heater from outside the outer insulating housing.

12. 12. The pressure transducer of claim 11, wherein the outer insulating housing includes a heater control port coupled to the heater and configured to transmit at least one of a control signal or a temperature measurement signal between an exterior of the outer insulating housing and the heater.

13. The pressure transducer of claim 1 , further comprising a fluid input tube coupled to the absolute pressure sensor and the outer insulating housing, the fluid input tube configured to deliver fluid to the fluid input.

14. The pressure transducer of claim 13 , wherein the fluid input tube and the outer insulating housing seal the space.

15. 15. The pressure transducer of claim 14, wherein the fluid input tube and the outer insulating housing are at least one of brazed to one another, welded to one another, or integrally constructed.

16. The pressure transducer of claim 1 , wherein the outer insulating housing comprises at least one of stainless steel, aluminum, Hastelloy™ alloy, Inconel™ alloy, or glass.

17. 2. The pressure transducer of claim 1, wherein the vacuum pressure between the housing and the absolute pressure sensor is less than atmospheric pressure.

18. 2. The pressure transducer of claim 1, wherein the vacuum pressure between the housing and the absolute pressure sensor is less than 100 Torr (about 13.3 kPa).

19. 2. The pressure transducer of claim 1, wherein the vacuum pressure between the housing and the absolute pressure sensor is less than 0.001 Torr (about 0.133 Pa).

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