Temperature sensor having a rotational response to the environment

Methods and systems of the invention are directed to a temperature sensor that includes a substrate, a first conductive plate, and a second conductive plate. The substrate is formed of a material having a low coefficient of thermal expansion (CTE). The first conductive plate is formed of a material having a CTE that is higher than the CTE of the substrate, and is attached to a first surface of the substrate. The second conductive plate is rotatably connected to the substrate through a hinge, and includes a portion that is adjacent to the first conductive plate.

FIELD

The present invention relates generally to temperature transducers and more particularly to transducers that shift a frequency of a reflected signal based on a response to temperature.

BACKGROUND

In operations, piping can extend hundreds or thousands of feet below ground to a well through a harsh environment. Devices have been used for monitoring downhole conditions of a drilled well so that efficient operation can be maintained. These downhole conditions include temperature and pressure, among others. A temperature sensor implemented in this environment should be robust and configured to operate within the potentially difficult environmental conditions. Likewise, a temperature sensor in this environment should be relatively insensitive to changes in pressure.

SUMMARY

A temperature sensor in accordance with an embodiment includes a substrate formed of a material having a first coefficient of thermal expansion, wherein the substrate has a first mount portion. The temperature sensor also includes a first conductive plate formed of a material having a second coefficient of thermal expansion that is higher than the first coefficient of thermal expansion. The first conductive plate is attached to a first surface of the substrate and the first conductive plate has a first contact portion. A second conductive plate of the temperature sensor has a second mount portion rotatably connected to the first mount portion of the substrate, the second conductive plate being adjacent to the first conductive plate.

A temperature sensor in accordance with an embodiment includes a first conductive element configured and arranged to generate a mechanical force in response to a temperature condition. The temperature sensor also includes a second conductive element configured and arranged to vary a capacitance in response to the mechanical force, the second conductive element having a first portion and a second portion such that the second conductive element establishes a distance between the first portion and the first conductive element via a rotation of the second portion about an axis of the first conductive element. The first portion of the second conductive element is adjacent to a surface of the first conductive element, and the second portion of the second conductive element is rotatably attached to a mounting portion of the first conductive element.

A method in accordance with an embodiment include measuring temperature in an enclosure using a system having a capacitive sensor with a first conductive plate having a high coefficient of thermal expansion and a second conductive plate rotatably attached to the first conductive plate. The method includes generating a signal having a predetermined frequency, shifting the frequency of the generated signal based on a rotation of the first conductive plate or second conductive plate due to the temperature of the enclosure, and correlating the frequency shift to a temperature value.

A system in accordance with an embodiment includes a receiver in an enclosure, a sensor, configured and arranged to modulate the electromagnetic signal based on a temperature in the enclosure, and a processor configured and arranged to correlate the modulated signal to a temperature value. The sensor includes first conductive elements configured and arranged to generate a mechanical force in response to a temperature condition. The sensor also includes a second conductive element rotatable about the first conductive element in response to the mechanical force, the second conductive element having a first portion and a second portion such that the second conductive element establishes a distance between the first portion and the first conductive element via a rotation of the second portion about an axis of the first conductive element. The first portion of the second conductive element is adjacent to a surface of the first conductive element, and the second portion of the second conductive element is rotatably attached to a mounting portion of the first conductive element.

DETAILED DESCRIPTION

FIG. 1is a schematic illustration of an embodiment directed to a temperature sensor100. The temperature sensor100includes a substrate102, a first conductor plate104, and a second conductor plate106.

The substrate102includes a first substrate layer108and a second substrate layer110. The first substrate layer108is formed from an insulating material, such as Maycor™ ceramic, for example, having a low coefficient of thermal expansion. The first substrate layer108contacts a bottom surface of the first conductor plate104. The second substrate layer110contacts a bottom surface of the first substrate layer108, and is connected to the second conductor plate106through a hinge112. The second substrate layer110is formed from a material having a coefficient of thermal expansion that is lower than the coefficient of thermal expansion of the first substrate layer108. In embodiments, the second substrate layer110may be formed from a material such as Invar®, for example. One of ordinary skill in the art will appreciate that the materials that make up the first substrate layer108and the second substrate layer110are not limited to Maycor™ and Invar®, respectively, and may be formed of any material that achieves the desired response.

The first conductor plate104is arranged on a top surface of the first substrate layer108, and is formed of a metal having a coefficient of thermal expansion that is greater than the coefficient of thermal expansion of the first substrate layer108. Aluminum is a suitable metal for use as the first conductor plate104, however one of ordinary skill in the art will appreciate that the first conductor plate104is not limited to this selection. Conductors having a linear coefficient of thermal expansion greater than about 10·10−61/K, and in particular, metals having such a coefficient, are well-suited to use in this embodiment. Examples include many types of steel, copper and aluminum, though the invention is not limited to these examples. The first conductor plate104includes a non-conductive portion104a. The non-conductive portion104ais a portion of the first conductor plate104that is anodized or otherwise processed to be non-conductive. The non-conductive portion104aincludes a tip portion that contacts the second conductor plate106such that a fulcrum is established.

The second conductor plate106includes a first leg106aand a second leg106b. The first leg106aextends in a plane that is substantially parallel to the first conductor plate104. The first leg106aand the first conductive means plate104are arranged such that a gap (G) of approximately ten one thousandths of an inch (0.010″), or lesser or greater, is established therebetween. The second leg106bis integrated with the first leg106aand extends in a plane that is substantially perpendicular to the direction of the first leg106a. In an embodiment, the first leg106aand the second leg106bcan be configured in an L-shape, for example, but may also be configured in any manner that achieves the desired response. The second leg106bincludes a hinge112to which the second substrate layer110is connected, and contacts the non-conductive portion104aof the first conductive means plate104.

The hinge112that is securely mounted to the second leg106band includes a metal sleeve and a pin.

The temperature sensor100may also include a mounting block114that is attached to a bottom surface of the substrate102. The mounting block114may include recessed portions for mounting the temperature sensor100to a rigid structure.

The mounting spring116connects an end of the mounting block114to the second leg106bof the second conductor plate106. The mounting spring116provides a restorative force that enables the gap (G) of the temperature sensor100to return to its original spacing at ambient temperatures. A positive stop, not shown, may be employed to avoid the spring enlarging the gap beyond a selected starting distance.

The temperature sensor100includes fasteners118and122that secure the substrate102, the first conductor plate104, and the mounting block114to one another. The fastener118extends from a top surface of the first conductor plate104to an interior portion of the substrate102. The second fastener122extends from a bottom surface of the mounting block114to an interior portion of the substrate102. The fasteners118and122can be implemented through a number of known fastening devices, such as a screw, tangs, pins, or rivets, for example. The fastener118may be adjusted along the length of the first conductive means plate104to a point where the fastener118does not effect the spacing of the gap (G).

A terminal120is arranged on the first conductor plate104. The terminal120is secured to the first conductor plate104through the fastener110. The terminal120extends from an outer end of the first conductor plate104. The terminal120is formed of conductive materials, such as a welded wire for example, and provides a connection to an external circuit.

During operation, as the temperature of the surrounding environment increases, the first conductor plate104expands in a lengthwise direction. This expansion of the first conductor plate104causes a force to be applied to the first leg106aof the second conductor plate106at the fulcrum of the non-conductive portion104a. The force created by the expansion of the first conductor plate104and the second conductor plate causes one of the conductor plates to rotate about the hinge112and adjust the spacing of the gap (G). The gap (G) may be adjusted in a range of approximately 0.010″ to 0.030″, or lesser or greater as desired. Whether the first conductor plate104or the second conductor plate106rotates about the hinge112is determined by which of the aforementioned components is mounted to a rigid structure.

For example, in an embodiment, the second conductor plate106may be attached or mounted to a rigid structure (not shown) through the second leg106b. As the external temperature increases, the degree of expansion undergone by the first conductor plate104determines an amount of force that the first conductor plate104applies to the second leg106bof the second conductor plate106at the fulcrum of the non-conductive portion104a. Because the second conductor plate106is securely mounted to a rigid structure, the amount of force applied by the first conductor plate104determines the angle at which the first conductor plate104(through its attachment to the substrate102) rotates about the hinge112.

In some embodiments, the mounting plate114is securely attached or mounted to a rigid structure. As the external temperature increases, the degree of lengthwise expansion of the first conductor plate104determines the amount of force that the first conductor plate104applies to the second leg106bof the second conductor plate106at the fulcrum of the non-conductive portion104a. Because the first conductor plate104is effectively mounted to the rigid structure through the mounting plate114, the amount of force applied by the first conductor plate104determines the angle at which the second conductor plate106rotates about the hinge112.

The angle of rotation about the hinge112of either the second conductor plate106or the substrate102is determined by the degree of lengthwise expansion realized by the first conductor plate104and the amount of bend (warping or bowing) realized by the first leg106aof the second conductor plate106, respectively. In response to an increase of the external temperature, the first conductor plate expands to thereby apply a force to the second conductor plate106through the fulcrum of the non-conductive portion104a. The amount of applied force determines the angle of rotation about the hinge112that is achieved by either of the first conductor leg104or the second conductor leg106.

As the temperature nears ambient levels, the lengthwise expansion of the first conductor plate104also decreases. As the expansion decreases, the first conductor plate104returns to its initial state. The mounting spring116restores the temperature sensor100to its original position by applying a force to rotate either the first conductor plate104or the second conductor plate106, depending on the mounting position, in an opposite direction about the hinge112.

In some embodiments, the temperature sensor100is composed of metal and ceramic materials that enable temperature measurements within a range of approximately 40° F. to 600° F., or lesser or greater as desired. The range of temperature measurements is determined by the resiliency of the materials along with the degree of expansion and the degree of warpage undergone by the conductor plates, respectively. The degree expansion of the conductor plate104is determined by the thickness and rigidity of the substrate102. For example, the substrate102may be a single or multilayered structure.

In an embodiment as shown inFIG. 2, the temperature sensor100includes the substrate102which is a single piece formed from ceramic or a non-conductive, hard, durable material. In some embodiments, the temperature sensor can be placed in a field container to protect the temperature sensor from contamination, as the temperature sensor100may monitor the temperature in a gas filled vessel or a liquid filled vessel.

FIG. 3illustrates a system300for measuring temperature in an enclosure (E) of an embodiment.

The enclosure (E) can be implemented in numerous shapes and sizes, for example, and can be implemented as a full or partial enclosure. The enclosure, as illustrated, is a representation of a full enclosure that is located below ground, such as a borehole or well, and contains a liquid or gas at a high temperature. The temperature of the liquid or gas in the enclosure may be measured at temperatures up to 600° F.

The system300also includes a high temperature generation unit302which may, in operation, generate high temperatures in the enclosure (E). The high temperature generation unit302can be represented by numerous industrial applications such as machinery used in drilling operations, manufacturing operations, or construction operations for example. One of ordinary skill in the art will appreciate that the high temperature generation unit302can be represented by any heater.

The system300includes a signal generator/receiver303for generating an electromagnetic signal, such as an RF signal or an electromagnetic pulse (EMP), for example. The electromagnetic signal can be generated in a range of 3 Hz to 30 GHz, or any other range suitable to achieve the desired response or to the environmental conditions.

The system300also includes a capacitive sensor100for establishing a capacitance based on the generated temperature. As shown inFIG. 1, the capacitive sensor100includes a first conductor for generating a mechanical force in response to the temperature generated by the high temperature generation unit302. The capacitive sensor100also includes a second conductor106configured to rotate about the first conductor as a result of the force generated by the first conductor104. The amount of rotation of the second conductor106is determined by the force generated by the first conductor104. The capacitive sensor100can be included in a resonant circuit304, where the change in capacitance of the capacitive sensor100shifts the frequency of a signal transmitted by a base station.

The resonant network304includes an inductor306that connects the resonant network304to an antenna308. The antenna308can be any electrical device suitable for receiving or sending a radio frequency (RF) signal or a more generalized electromagnetic signal, e.g., such as cabling, conductive piping, or a coil. The resonant network304also includes a network resistance312and a network inductance314. The resonant network304receives the RF signal through the antenna308, and “rings” or resonates at its natural frequency. The capacitive sensor100is configured to sense the temperature of the enclosure (E) and modulate the vibration frequency induced in the resonant network304when the RF signal is received by the antenna308. The capacitive sensor100modulates the frequency of the RF signal based on the size of the gap (G).

The system300also includes a correlator316for correlating the modulated frequency to a temperature value. Those of ordinary skill will appreciate that the correlator may be a processor, computer, or other processing device located at a base station. The correlator316may perform any desired processing of the modulated signal including, but not limited to, a statistical analysis of the modulated frequency. Commercial products are readily available and known to those skilled in the art can be used to perform any suitable frequency detection. For example, a fast Fourier transform that can be implemented by, for example, MATHCAD available from Mathsoft Engineering & Education, Inc. or other suitable product to deconvolve the modulated ring received from the resonant network304. The processor can be used in conjunction with a look-up table having a correlation table of modulation frequency-to sensed characteristics (e.g., temperature, pressure, and so forth) conversions.

FIG. 4is a flowchart illustrating a method of measuring the temperature of an enclosure in an embodiment. The method is executed using the capacitive sensor100as described with respect toFIG. 1. As shown in step400, a predetermined frequency electromagnetic signal, such as an RF signal or electromagnetic pulse, is generated by a base station and transmitted to the resonant network304that includes the capacitive sensor100. The capacitive sensor100modulates the received electromagnetic signal based on the temperature of the enclosure (step402). Specifically, capacitive sensor100shifts the frequency due to an adjustment in the size of the gap (G), whereby at least one of the conductor plates of the sensor100undergoes a lengthwise expansion, which causes a rotation increase the gap (G) established between the conductor plates.

The resonant network304emits a signal having at the shifted (modulated) frequency of the conductor plates about a hinge to the base station (step404). The base station correlates the shifted frequency to a temperature value so that the observed temperature of the enclosure may be determined (step406).

While the invention has been described with reference to specific embodiments, this description is merely representative of the invention and is not to be construed as limiting the invention. Various modifications and applications may occur to those skilled in the arts without departing from the true spirit and scope of the invention as defined by the appended claims.