Pressure transducers having improved resistance to temperature error
The introduction of electromechanical pressure sensors in a thermally managed package addresses the limitations of conventional pressure gauges, offering improved accuracy, stability, and resistance to contamination across a broader operating range.
Patent Information
- Application Number
- JP2024193371
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-10-31
- Filing Date
- 2024-11-05
- Publication Date
- 2025-05-19
AI Technical Summary
Conventional pressure gauges suffer from insufficient operating range, varying accuracy over a partial range, and instability over the life of the sensor, making them less reliable for precise pressure measurements.
The development of pressure transducers that incorporate an electromechanical pressure sensor packaged to reduce temperature-induced errors, featuring a housing with a fluid inlet, a microelectromechanical pressure sensor, and a heater to maintain a target temperature, thereby enhancing accuracy and stability.
These pressure transducers demonstrate higher accuracy and stability over a wider operating range compared to conventional gauges, with errors less than 0.1500% of the reading, and are less susceptible to contamination-induced errors.
Smart Images
Figure 2025078065000001_ABST
Abstract
Description
Technical Field
[0001] [Related Applications] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 596,029, filed on November 3, 2024, entitled "PRESSURE TRANSDUCERS HAVING IMPROVED RESISTANCE TO TEMPERATURE ERROR". The entire disclosure of U.S. Provisional Patent Application No. 63 / 596,029 is hereby incorporated by reference in its entirety.
[0002] This disclosure generally relates to pressure transducers, and more specifically to pressure transducers having improved resistance to temperature error.
Background Art
[0003] A pressure sensor or pressure transducer measures the pressure of a fluid input to the sensor that is compared to a reference pressure. A pressure sensor can be constructed to compare the input pressure to a fixed reference pressure or a variable reference pressure.
Summary of the Invention
[0004] A pressure transducer having improved resistance to temperature error is disclosed, substantially as shown by at least one of the drawings and described in connection therewith, as more fully set forth in the claims.
[0005] These features, aspects, and advantages of the present disclosure, as well as other features, aspects, and advantages, will be better understood when the following detailed description is read in conjunction with the accompanying drawings, in which like reference numerals represent like parts throughout.
Brief Description of the Drawings
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Figure 1
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[0010] The drawings are not necessarily to scale. Where appropriate, like or identical reference numerals are used to refer to like or identical components.
[0011] With the aim of facilitating the understanding of the principles of the claimed technology and presenting its currently understood best mode of operation, reference is made herein to the embodiments shown in the drawings and this is described using specific terms. However, it will be understood that this is not intended to limit the scope of the claimed technology, and such changes and further modifications in the illustrated apparatus, as well as such further applications of the principles of the claimed technology as described herein, would be typical of those that would occur to a person skilled in the art related to the claimed technology.
[0012] Conventional pressure gauges use a pressure measurement assembly that has high accuracy over a certain range. However, conventional pressure gauges may have an insufficient operating range and / or the accuracy may vary over a partial range of the operating range. Furthermore, conventional pressure gauges may be unstable over the life of the sensor.
[0013] The disclosed exemplary pressure transducers have higher accuracy and / or higher stability over the same operating pressure than conventional pressure gauges. In particular, the disclosed exemplary pressure transducers include an electromechanical pressure sensor that provides high accuracy and stability and is packaged to reduce temperature-induced errors. This packaging and nature of the electromechanical pressure sensor make the disclosed exemplary pressure transducers less susceptible to errors caused by the accumulation of contaminants in the process fluid.
[0014] The disclosed exemplary pressure transducers include a housing, a fluid inlet configured to supply fluid to a first cavity within the housing, a pressure measurement assembly having a microelectromechanical pressure sensor configured to output a signal representative of the pressure within the first cavity, and a heater configured to heat the pressure measurement assembly based on a target temperature.
[0015] In some exemplary pressure transducers, the microelectromechanical pressure sensor includes a resonant pressure sensor formed by trench etching. In some exemplary pressure transducers, the pressure measurement assembly includes a diaphragm that at least partially defines the first cavity. In some exemplary pressure transducers, the measurement diaphragm is configured to transmit the pressure from the first cavity to the microelectromechanical pressure sensor. In some exemplary pressure transducers, the pressure measurement assembly includes a sensor cavity, and the microelectromechanical pressure sensor is disposed within the sensor cavity. In some exemplary pressure transducers, the sensor cavity further includes an incompressible fluid configured to transmit the pressure applied by the diaphragm to the microelectromechanical pressure sensor.
[0016] In some exemplary pressure transducers, the heater comprises a first zone heater configured to heat the housing based on a target temperature and a second zone heater configured to heat the pressure measurement assembly based on the target temperature. In some exemplary pressure transducers, the microelectromechanical pressure sensor is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure of at least 1 torr (about 1.3x10 2 Pa) to 100 torr (about 1.3x10 4 Pa). In some exemplary pressure transducers, the microelectromechanical pressure sensor is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure of at least 10 torr (about 1.3x10 3 Pa) to 1000 torr (about 1.3x10 5 Pa). In some exemplary pressure transducers, the microelectromechanical pressure sensor is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure of at least 1 torr (about 1.3x10 2 Pa) to 1000 torr (about 1.3x10 5 Pa). In some exemplary pressure transducers, the threshold error is less than 0.1500% of the reading.
[0017] Some exemplary pressure transducers further comprise a measurement circuit configured to apply a drive signal to the microelectromechanical pressure sensor, measure the frequency of the result signal output by the microelectromechanical pressure sensor, and determine the measured pressure based on the frequency. In some exemplary pressure transducers, the pressure measurement assembly comprises a plurality of electrodes extending through the housing from the pressure measurement assembly, and the measurement circuit is configured to apply a drive signal through at least one of the electrodes.
[0018] In some exemplary pressure transducers, the heater comprises a heating element configured to heat the pressure measurement assembly, a temperature sensor configured to measure the temperature of the pressure measurement assembly, and a control circuit configured to control the heating element based on the measured temperature.
[0019] FIG. 1 is a block diagram of an exemplary process control system 100 that includes a pressure transducer 102. The exemplary process control system 100 of FIG. 1 includes a process chamber 104, and the pressure transducer 102 is fluidly coupled to the process chamber 104 via a fluid input line 106 to measure the pressure in 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 that can be controlled via mass flow controllers 110a, 110b.
[0021] The exemplary system 100 can include a vacuum pump 112 or other pressure control pump, and a valve 114 that controls the flow rate between the vacuum pump 112 and the process chamber 104. The valve 114 is controlled by a controller 116, a computing device, and / or any other control technique, and can maintain the pressure within the process chamber 104 within a desired range. The exemplary pressure transducer 102 is communicatively coupled to the controller 116 and supplies pressure feedback to the controller 116 (e.g., for use in a pressure control loop). For example, when the pressure in the process chamber 104 increases, the pressure transducer 102 measures the pressure and supplies a signal representative of the pressure to the controller 116, which then controls the valve 114 to increase the flow rate from the process chamber 104 to the vacuum pump 112. The vacuum pump 112 can have an output to any suitable location, based on the nature of the process.
[0022] In the example of FIG. 1, the pressure transducer 102 is configured to have a fixed pressure 118, and the input pressure of the fluid received via the fluid input line 106 is compared with the fixed pressure 118 to output a pressure signal. For example, as will be described in more detail below, the pressure transducer 102 can be provided with a sealable exhaust port that can be sealed when a desired pressure is supplied into the pressure transducer 102, and / or the pressure transducer 102 can be assembled and sealed in a volume having a desired reference pressure. The fixed pressure 118 can be a vacuum pressure, or another predetermined fixed reference pressure that is lower than, equal to, or higher than the nominal atmospheric pressure. In the configuration of FIG. 1, the pressure transducer 102 can be used as an absolute pressure sensor.
[0023] FIG. 2 is a schematic diagram of an exemplary pressure transducer 200 that can be used to implement the pressure transducer 102 of FIG. 1. The exemplary pressure transducer 200 includes a pressure measurement assembly 202 and a housing 204. The pressure transducer 200 receives fluid via a fluid input line 208 (e.g., the fluid input line 106 of FIG. 1), measures the absolute pressure of the received fluid, and outputs one or more signals representing the measured pressure.
[0024] FIG. 3 is a perspective view of the exemplary pressure measurement assembly 202 of FIG. 2. FIG. 4 is another perspective view of the exemplary pressure measurement assembly 202 of FIG. 2. Referring to FIG. 2, the pressure measurement assembly 202 defines a measurement cavity 222 attached to the fluid input line 208. Also, the exemplary fluid input line 208 is fixed and sealed to the housing 204 (e.g., via a flange). The pressure measurement assembly 202 can also be referred to as a "sensor core" in that it performs measurements and converts them into output signals. The pressure measurement assembly 202 is at least partially surrounded by the housing 204. The housing 204 can provide thermal insulation and / or physical protection to the pressure measurement assembly 202.
[0025] In the illustrated example, the pressure measurement assembly 202 includes a microelectromechanical pressure sensor 206 coupled to a diaphragm 210. In some examples, the microelectromechanical pressure sensor 206 is a resonant pressure sensor formed by trench etching or an in-plane resonant structure formed by other silicon micromachining, in which the microelectromechanical pressure sensor 206 outputs an output signal having a resonant frequency based on the pressure applied to the diaphragm 210. An exemplary resonant pressure sensor formed by trench etching that can be used to implement the microelectromechanical pressure sensor 206 is described in “Advances in Core Fundamental Sensor Technologies Enabling Improvements in the Metrological Transfer Standards of Pressure Measurement,” Moisoi, et al., Metrologist - NCSLI Worldwide News, Vol. 15, No. 2, pp. 46-55 (2002) (“Moisoi”). The entirety of Moisoi is incorporated herein by reference.
[0026] The diaphragm 210 is exposed to the pressure in the measurement cavity 222 and transmits the pressure to the microelectromechanical pressure sensor 206 via an incompressible fluid in the sensor cavity 212. The microelectromechanical pressure sensor 206 is disposed at an end of the sensor cavity 212 remote from the diaphragm 210, and the incompressible fluid fills the remainder of the sensor cavity 212. In some examples, the incompressible fluid is an incompressible oil, and the incompressible oil may further be non-conductive. Additionally or alternatively, the microelectromechanical pressure sensor 206 includes a second diaphragm, such as a silicon diaphragm, that electrically insulates the microelectromechanical pressure sensor 206 from the incompressible fluid while transmitting the force from the fluid to the resonant components of the microelectromechanical pressure sensor 206.
[0027] The diameter of the diaphragm 210 can be increased or decreased to further increase or decrease the sensitivity of the pressure measurement assembly 202.
[0028] The microelectromechanical pressure sensor 206 is coupled to the measurement circuit section 214 via ports 220, 222 for supplying an input signal and / or an output signal. The pressure measurement assembly 202 can define a thermal oven chamber 216 in fluid communication with the ambient pressure. The exemplary microelectromechanical pressure sensor 206 can have an integrated pressure reference sealed within the microelectromechanical pressure sensor 206. For example, a silicon diaphragm within the microelectromechanical pressure sensor 206 separates the pressure reference from the sensor cavity 212, and the resonant element of the microelectromechanical pressure sensor 206 is present within the reference pressure cavity of the microelectromechanical pressure sensor 206. The microelectromechanical pressure sensor 206 measures the pressure applied to the diaphragm 210 with respect to the reference pressure in the integrated pressure reference. The integrated pressure reference within the microelectromechanical pressure sensor 206 can be established, for example, during the construction of the microelectromechanical pressure sensor 206.
[0029] In the example of FIG. 2, the surface of the diaphragm 210 has a circular convolution that can be concentric with the diaphragm 210, which allows for axial deflection of the diaphragm 210 with a minimum change in internal tension and can improve the linearity of the microelectromechanical pressure sensor 206. Since the pressure applied to the diaphragm 210 is measured by the microelectromechanical pressure sensor 206 (e.g., by measuring the change in the resonant frequency of the driven circuit), the accuracy of the microelectromechanical pressure sensor 206 is improved by increasing the linear motion of the diaphragm 210.
[0030] The pressure transducer 200 further includes one or more heaters 218 that raise the temperature of the microelectromechanical pressure sensor 206 (e.g., to reduce the effects caused by the thermal gradient between the microelectromechanical pressure sensor 206 and the process fluid(s)). Exemplary heaters 218 can be disposed on the outer periphery of the housing 204 and / or within the housing 204, as well as on the outer periphery of the pressure measurement assembly 202. In some examples, the heater(s) 218 are controlled to heat the microelectromechanical pressure sensor 206 to a set temperature that is at least the expected process temperature of the fluid received, in some cases, via the fluid input line 208. In some examples, one or more heat spreaders are disposed in contact between the heater(s) 218 and the housing 204 and / or between the heater(s) 218 and the microelectromechanical pressure sensor 206 to more effectively distribute heat over a wider area of the housing 204 and / or the microelectromechanical pressure sensor 206 and reduce the thermal gradient. The housing 204 can be constructed using a heat-conductive material to reduce the temperature gradient within the housing 204. Additional and / or alternative locations for the heater 218 can include the bottom surface of the second body 226, the top surface of the first body 224, and / or the periphery of the fluid input line 208.
[0031] The heater 218 can improve the measurement accuracy by the microelectromechanical pressure sensor 206 and / or the measurement stability over the life of the microelectromechanical pressure sensor 206 across a wide range of input pressures. The heater(s) 218 can protect against longer-term errors due to process-induced shift. In FIG. 2, two exemplary heaters 218 are shown heating two different zones, but the pressure transducer 200 can include more or fewer heaters 218 and / or more or fewer heating zones.
[0032] In some examples, the microelectromechanical pressure sensor 206 is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure in a pressure range that includes at least 1 Torr (about 1.3x10 2 Pa) to 100 Torr (about 1.3x10 4 Pa) (e.g., a pressure range that includes at least 1 Torr (about 1.3x10 2 Pa) to 100 Torr (about 1.3x10 4 Pa) and may include pressures less than 1 Torr (about 1.3x10 2 Pa) and / or greater than 100 Torr (about 1.3x10 4 Pa)). In some examples, the microelectromechanical pressure sensor 206 is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure of at least 10 Torr (about 1.3x10 3 Pa) to 1000 Torr (about 1.3x10 5 Pa). In some examples, the microelectromechanical pressure sensor 206 is configured to output a pressure measurement signal with an error less than a threshold value for a fluid having a pressure of at least 1 Torr (about 1.3x10 2 Pa) to 1000 Torr (about 1.3x10 5 Pa). An exemplary threshold error is 0.1500% of the measurement output (read value). In other examples, the pressure transducer 200 can be configured to use other pressure ranges as an operating range that may include a two-digit range or a three-digit range (on the Torr scale) and / or a larger operating range while maintaining an error less than the threshold value over the operating range.
[0033] The pressure transducer 200 further includes a control circuit unit 228. The control circuit unit 228 receives a measurement value from the measurement circuit unit 214, controls the heater power supply 230 to supply power to the heater 218, and receives a temperature feedback signal from the heater 218 and / or the temperature sensor 232 on the sensor housing 204.
[0034] The control circuit unit 228 can be implemented using at least one controller or processor that controls the operation of the pressure transducer 200. The control circuit unit 228 receives and processes a plurality of inputs. The control circuit unit 228 can include one or more microprocessors, such as one or more "general-purpose" microprocessors, one or more dedicated microprocessors and / or ASICs, and / or any other type of processing device. For example, the control circuit unit 228 can include one or more digital signal processors (DSPs). The control circuit unit 228 can further include a memory device or a data storage device.
[0035] The exemplary measurement circuit unit 214 is connected to the output port 220 to receive a measurement signal (or signals in some cases), and / or is connected to the input port 222 to supply an input or drive signal that drives the resonance of the microelectromechanical pressure sensor 206. For example, the measurement circuit unit 214 can apply a drive signal to the microelectromechanical pressure sensor 206 via the input port 222, measure the frequency of the result signal output by the microelectromechanical pressure sensor 206 via the output port 220, and determine the pressure measured based on the frequency. For example, the measurement circuit unit 214 can be calibrated for combinations of frequency and pressure after construction.
[0036] An additional port can supply heating power to the heater 218 and / or supply temperature sensor data from the temperature sensor 232 to the control circuit unit 228 to control the heater 218.
[0037] The housing 204 includes a first body 224 and a second body 226. The second body 226 is coupled to the fluid input line 208. For example, the second body 226 can be coupled to the fluid input line 208 by welding, brazing, or other means so as to promote or improve heat conduction. The first body 224 is coupled to the second body 226 so as to enclose the pressure measurement assembly 202 within the housing 204. The first body 224 can further include openings through which ports 220, 222 extend for connection to the measurement circuit portion 214 and / or the control circuit portion 228.
[0038] Compared with a conventional capacitive sensor in which a diaphragm is part of a capacitive electrode and the sensor output depends on the displacement of the diaphragm, the exemplary microelectromechanical pressure sensor 206 has a reduced sensitivity to contamination (e.g., particulates from the input line 208) on the diaphragm 210. Instead of affecting the capacitance depending on the sensitivity of the diaphragm 210, the diaphragm 210 transmits the pressure in the measurement cavity 222 to the incompressible fluid in the sensor cavity 212. Thus, the life of the microelectromechanical pressure sensor 206 can be extended even in applications where contamination is likely to occur, and the microelectromechanical pressure sensor 206 can be packaged in a smaller package than a conventional sensor by eliminating, for example, a guard volume that reduces contamination on the diaphragm.
[0039] The exemplary pressure transducer 200 can further include a communication circuit section 234 that communicates measurement values to an external computing device or control device (e.g., the controller 116 of FIG. 1). For example, the communication circuit section 234 can include any wired and / or wireless communication circuit section. In some examples, the communication circuit section 234 performs digital communication that transmits the digital measurement values output by the measurement circuit section 214. By using digital communication such as EtherCAT, the precise measurement values created using the microelectromechanical pressure sensor 206 are retained during communication. Further, the communication circuit section 234 can receive command signals supplied to the control circuit section 228. Exemplary command signals include configuration information, such as a target heating temperature, a temperature reporting interval, and / or any other desired configuration information.
[0040] The present device and / or method can be implemented in hardware, software, or a combination of hardware and software. The present method and / or system can be implemented in a centralized manner in at least one computing system, processor, and / or other logic circuits, or can be implemented in a distributed manner in which different elements are spread across a plurality of interconnected computing systems, processors, and / or other logic circuits. Any type of computing system or other device adapted to execute the methods described herein is also suitable. A typical combination of hardware and software may be a processing system integrated into a welding power source that includes a program or other code for controlling the welding power source so as to execute the methods described herein when loaded and executed. Another typical embodiment can include application-specific integrated circuits or chips such as field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), or complex programmable logic devices (CPLDs), and / or system-on-chip (SoC). Some embodiments can include non-transitory machine-readable (e.g., computer-readable) media (e.g., flash memory, optical disks, magnetic storage disks, etc.), such non-transitory machine-readable media storing one or more lines of machine-executable code, thereby causing a machine to perform a process as described herein. As used herein, the term "non-transitory machine-readable media" includes all types of machine-readable storage media and is defined to exclude propagated signals.
[0041] As used herein, "and / or" means any one or more of the items in the list connected by "and / or". By way of example, "x and / or y" means any of the three elements in the 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 of the seven elements in the 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" serves 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 has been described with reference to certain embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted without departing from the scope of the method and / or system. For example, the blocks and / or components of the disclosed examples can be combined, divided, rearranged, and / or otherwise changed. In addition, many modifications can be made to adapt the teachings of the disclosure to specific situations or materials without departing from the scope of the disclosure. Accordingly, the method and / or system is not limited to the specific embodiments disclosed. Instead, the method and / or system includes all embodiments that fall within the scope of the appended claims, literally or under the doctrine of equivalents.
Claims
1. 1. A pressure transducer comprising: Housing and a fluid inlet configured to supply fluid to a first cavity within the housing; a pressure measurement assembly including a microelectromechanical pressure sensor configured to output a signal representative of a pressure in the first cavity; a heater configured to heat the pressure measurement assembly based on a target temperature; A pressure transducer comprising:
2. 10. The pressure transducer of claim 1, wherein the microelectromechanical pressure sensor comprises a resonating pressure sensor formed by trench etching.
3. 10. The pressure transducer of claim 1, wherein the pressure measurement assembly comprises a diaphragm at least partially defining the first cavity.
4. The pressure transducer of claim 3 , wherein the measuring diaphragm is configured to transmit the pressure from the first cavity to the micro-electro-mechanical pressure sensor.
5. 5. The pressure transducer of claim 4, wherein the pressure measurement assembly comprises a sensor cavity, and the microelectromechanical pressure sensor is disposed within the sensor cavity.
6. The pressure transducer of claim 5 , wherein the sensor cavity further comprises an incompressible fluid configured to transfer the pressure applied by the diaphragm to the micro-electromechanical pressure sensor.
7. The heater is a first zone heater configured to heat the housing based on the target temperature; a second zone heater configured to heat the pressure measurement assembly based on the target temperature; 10. The pressure transducer of claim 1 comprising:
8. The microelectromechanical pressure sensor has a pressure sensitivity of at least 1 Torr (approximately 1.3×10 ２ Pa) to 100 Torr (approx. 1.3 x 10 4 10. The pressure transducer of claim 1, configured to output a pressure measurement signal below a threshold error for a fluid having a pressure of 100 psi (10 Pa).
9. The microelectromechanical pressure sensor has a pressure sensitivity of at least 10 Torr (approximately 1.3×10 3 Pa) to 1000 Torr (approximately 1.3 x 10 5 10. The pressure transducer of claim 1, configured to output a pressure measurement signal below a threshold error for a fluid having a pressure of 100 psi (10 Pa).
10. The microelectromechanical pressure sensor has a pressure sensitivity of at least 1 Torr (approximately 1.3×10 ２ Pa) to 1000 Torr (approximately 1.3 x 10 5 10. The pressure transducer of claim 1, configured to output a pressure measurement signal below a threshold error for a fluid having a pressure of 100 psi (10 Pa).
11. 11. The pressure transducer of claim 10, wherein the threshold error is less than 0.1500% of reading.
12. A measurement circuit unit, applying a drive signal to the microelectromechanical pressure sensor; measuring a frequency of a resultant signal output by the microelectromechanical pressure sensor; determining a measured pressure based on said frequency; 10. The pressure transducer of claim 1, further comprising measurement circuitry configured to:
13. 13. The pressure transducer of claim 12, wherein the pressure measurement assembly includes a plurality of electrodes extending from the pressure measurement assembly through the housing, and the measurement circuitry is configured to apply the drive signal via at least one of the plurality of electrodes.
14. The heater is a heating element configured to heat the pressure measurement assembly; a temperature sensor configured to measure a temperature of the pressure measurement assembly; control circuitry configured to control the heating element based on the measured temperature; 10. The pressure transducer of claim 1 comprising: