Abstract: A die cushion apparatus of a press machine which makes possible to manufacture a plurality of types of products of different sizes by one press machine and capable of minimizing a production facility, and which comprises a plurality of die cushion units, each having a cushion pad and a rise and fall drive unit for vertically driving the cushion pad, that are aligned in a direction perpendicular to a work conveying direction, and a control unit capable of individually and independently controlling the plurality of die cushion units.

Abstract: A process for designing and manufacturing precision-folded, high strength, fatigue-resistant structures and a sheet therefore. The techniques include methods for precision bending of a sheet of material (41, 241, 341, 441, 541) along a bend line (45, 245, 345, 445, 543) and a sheet of material formed with bending strap-defining structures, such as slits or grooves (43, 243, 343, 443, 542), are disclosed. Methods include steps of designing and then separately forming longitudinally extending slits or grooves (43, 243, 343, 443, 542) through the sheet of material in axially spaced relation to produce precise bending of the sheet (41, 241, 341, 441, 541) when bent along the bend line (45, 245, 345, 445, 543). The bending straps have a configuration and orientation which increases their strength and fatigue resistance, and most preferably slits or arcs are used which causes edges (257, 457) to be engaged and supported on faces (255, 455) of the sheet material on opposite sides of the slits or arcs.

Abstract: A procedure for the calibration of the lambda measuring signal supplied by the wideband lambda sensor, which is disposed in the exhaust gas area of an internal combustion engine, and a device to implement the procedure are proposed. During the procedure, a correction value is used to ascertain a unit of measurement for the lambda actual value, whereby the correction value is ascertained during a specified operating state of the internal combustion engine, in which no fuel metering occurs and the engine rotational speed of the internal combustion engine lies above a threshold value. The correction value—is ascertained as a function of the sensor temperature of the wideband lambda sensor during a specified operating state.

Abstract: The invention relates to a method, particularly suitable for the extraction and enrichment of a volatile component from a liquid, solid or gaseous sample for subsequent introduction into an analytical device, for example, a gas chromatograph. The sample is flushed through a packing of extraction material for extraction of the analytes of interest. A suitable device comprises a syringe with a hollow needle. A chamber is provided between the needle and syringe, in which the extraction material is arranged.

Abstract: A gas sensor is disclosed having an element holder body with which a senor element is fixedly supported, and an atmosphere-side insulator covering a base portion of the sensor element and providing electrical connection between lead wires and terminal electrodes of the sensor element. The element holder body includes a housing and an element-side insulator fixedly mounted in the housing. The atmosphere-side insulator incorporates therein a plurality of spring terminals held in electrical contact with the electrode terminals of the sensor element. At least one of the element holder body and the atmosphere-side insulator carries thereon convexed portions with which the atmosphere-side insulator can tilt with respect to the element holder body.

Abstract: A knock sensor includes: a base made up of a flange portion, and a tube portion; a sensor main body including a piezoelectric element that is fitted over an outer peripheral portion of the tube portion; and a stopper ring that is fitted over the outer peripheral portion of the tube portion and cooperates with the flange portion to clamp the sensor main body, a groove being formed on the outer peripheral surface of the tube portion, and the knock sensor being fixed by driving a pressing jig into an outer peripheral surface of the stopper ring to plastically deform the stopper ring and press a protruding portion into the groove, wherein: an axial length of a recess portion that is formed simultaneously on the outer peripheral surface of the stopper ring when the protruding portion is formed is longer than an axial length of the groove.

Abstract: The present invention relates to the use of an electronically controlled humidity chamber with temperature controls: to determine, by vapor desorption, high capillary pressures of core samples; to produce core samples with a high capillary pressure for testing electrical properties; and, using a curve of high capillary pressures from vapor desorption data, to transform a curve of high capillary pressures determined from high pressure mercury injection.

Abstract: Apparatus and method is provided for reliably testing a quality level of bead fusion in molded foam parts. Such apparatus may be portable and hand-held, and the test procedure will not destroy or damage tested products. In a useful embodiment comprising apparatus for monitoring quality of a molded foam part, an insertion device introduces a stream of selected gas under pressure into the interior of the molded foam part. The insertion device may include a thin nozzle to be inserted into the part. Poorly fused beads allow a faster flow rate of the gas than well fused beads, since the poor fusion will provide more openings for the gas to escape. Accordingly, the embodiment includes a sensor for measuring the flow rate of the stream of gas, as the stream is introduced into the part interior.

Abstract: A leak inspection device comprises: a vacuum chamber 2 for accommodating a product 1; a vacuum pump 3 for discharging air from the vacuum chamber; a He gas bomb 4 for supplying and charging He gas into the product; and a leak detector 5 for detecting He gas which has leaked out from the product, wherein a heater 8 is provided on an outer wall of the vacuum chamber and an inner surface temperature of the vacuum chamber is maintained to be higher than the temperature of the outside air. Due to the above constitution, moisture contained in the atmosphere is not attached onto the inner surface of the vacuum chamber.

Abstract: A method of hydrostatic testing a selected section of a pipeline having fluid flow therethrough, including the steps of introducing into the pipeline a pig train including a leading seal pig, a supply liquid slug, a first isolation tool, a test liquid slug and a second isolation tool; permitting the train to traverse the pipeline interior by the force of fluid flow until the lead isolation tool is forwardly of and the second isolation tool is rearwardly of the selected selection of the pipeline; securing the position of the pig train by applying exteriorly of the pipeline appropriate signals to actuate the isolation tools to each engage and seal the interior of the pipeline trapping the test liquid slug therebetween; and pumping liquid from the supply liquid slugs into the test liquid slug to a hydrostatic testing pressure. In addition to testing, the pipeline can be repaired by moving the pig train into position where a defective area can be isolated by additional isolation tools.

Abstract: An intrinsically safe, precise, and cost effective storage tank leak detection system. Embodiments include a highly precise quartz crystal type pressure transducer, secured in a vacuum and held at a constant temperature. Said transducer is used in combination with data correction and regression techniques to yield a storage tank leak detection system with an extremely low leak detection threshold. The storage tank leak detection system is thought to be most useful for detecting very small leaks in very large storage tanks.

Abstract: A concentration detector is disclosed, which is adapted to detect a concentration of a liquid fuel in a container. The concentration detector includes a rotating means positioned underneath a level of a liquid fuel and rotatable at an angle ? on a X-Y plane. The rotating means includes at least three floating objects connected with each other. Each floating object has a specific gravity less than a specific gravity of the liquid fuel ?. The floating objects are balanced according to a torque equation, F(?,?)=0, such that the rotating means is still under the level of the liquid fuel. While a concentration of the liquid fuel is changed and the angle ? of the rotating means is detected, the specific gravity of the liquid fuel ? is obtained from the torque equation, F(?,?)=0, and thereby computing the concentration of the liquid fuel.

Abstract: A liquid state detecting apparatus including a detecting element which outputs a signal associated with a concentration of a particular component of a liquid contained in a liquid container; an abnormality determination unit which determines whether or not the liquid is in a particular abnormal state based on the output signal of the detecting element, a level detecting part which outputs a signal according to a level of the liquid contained in the liquid container; and a static state determination unit which determines whether or not the liquid in the liquid container is in a static state based on the output signal from the level detecting part, wherein the determination made by the static state determination unit is reflected in the determination made by the abnormality determination unit.

Abstract: A method of measuring the frequency characteristics of a golf club shaft by taking measurements at a plurality of predetermined locations along the length of the shaft being measured. These measurements are used to determine the overall characteristics of the shaft. This method enables shafts to be matched at each measurement location in order to perform in a similar, if not identical manner when used by a golfer to execute golf shots.

Abstract: A method for determining the water resistance of glass fiber based insulation to wetting by water is disclosed. The method generally comprise the steps of placing a sample of insulation into contact with a source of water for a defined period of time; removing the insulation sample from the water containing surface; draining the sample for a prescribed period of time, and determining the water resistance according to certain formulas or observations.

Abstract: A production method of an indentation curve is given, in which when an indentation curve showing a relationship between indentation force and indentation depth in a process of indenting an indenter into a surface of a sample is produced, a measurement range using an (i-n)th (here, i and n are natural numbers) measurement value as a reference is provided, and the indentation depth or indentation force is temporarily measured when the indentation force or indentation depth is gradually changed, respectively, and when a temporarily measurement value obtained by the temporarily measurement is out of the determination range, indentation depth at the relevant indentation force or indentation force at the relevant indentation depth is measured and set as an ith measurement value, or the temporarily measurement value is used as the ith measurement value.

Abstract: Method provided for implementation in a data processing device for monitoring a permissible integrity of a measured variable of a dynamic system with the steps: Determination of at least one measurement series with respectively one number (n) of measurements (zk) by means of at least one sensor device with respectively one predetermined measuring accuracy (?zk) and a predetermined actual sensor integrity ({1?pk}) related thereto, determination of a number (m) of measuring errors as a function of the actual sensor integrities ({1?pk}), as a function of the number (n) of measurements and as a function of a minimum integrity ({1?p0}), assignment of the determined accuracy range to an accuracy measurement, comparison of the determined accuracy measurement with a threshold value, and issuing a warning as soon as a desired value has been reached, fallen below or exceeded.

Abstract: In a probe apparatus that intermittently irradiates a sample with excitation light to observe the sample while subjecting a cantilever including a probe arranged to face a surface of the sample to self-excited vibration at a predetermined frequency, the sample is irradiated with the excitation light at a predetermined timing when a distance between the probe and the sample is not greater than a predetermined distance.

Abstract: The invention relates to a method for detecting fluctuating fuel properties during the operation of a power plant. According to the inventive method, the actual operating characteristics of the power plant are used to determine the efficiency of the power plant and a change in fuel properties is concluded from a temporal change in the efficiency so determined.

Abstract: An engine idle fault control system that identifies a source of rough idle in an engine includes a first module that monitors an idle speed of the engine and that generates a rough idle signal, and a second module that monitors a fuel control parameter. A third module determines a source of rough idle based on the fuel control parameter and the rough idle signal.

Abstract: A leak check apparatus performs a leak check of a fuel vapor processing apparatus based on a change in a negative pressure in a purge line during leak down. The pressure change during leak down is corrected by measuring an amount of vapor generated after the purge line is opened to the atmosphere. A first pressure change rate of the purge line is measured after a predetermined negative pressure is applied to the purge line, and the purge line is sealed at the negative pressure. A second pressure change rate of the purge line is measured after the first pressure change rate of the purge line is measured, the cut valve is opened to expose the purge line to the atmosphere, and the purge valve and the cut valve are closed to seal the purge line at the atmospheric pressure. The second pressure change rate measurement does not begin until the degree of pressure increase in the purge line exceeds a predetermined reference value.

Abstract: A lag time is set in a period from the time when a leak down is finished to the time when measurement of the amount of fuel vapor is started for the purpose of returning a deformed fuel tank to its original shape. A fuel vapor amount estimating means is provided that estimates the amount of fuel vapor produced in the fuel tank during the time of the leak down. This means is so set as to make the lag time shorter as the amount of fuel vapor increases. With this, undesired precision in measuring the amount of fuel vapor produced under a condition wherein the amount of fuel vapor is large can be avoided.

Abstract: The invention relates to a tyre-inflation method and to a device and machine which are used to carry out said method. The inventive method consists in adjusting the pressure of a tyre (5) according to a corrected set value Pcc which is calculated using formula (I), wherein: Pc is a set value recommended by a car manufacturer and a tyre producer; Tp is the temperature of the tyre (5), which is supplied by a temperature sensor installed in the tyre; and Tref is a variable reference temperature which is selected as being the lowest temperature from the instantaneous ambient temperature measured (37) at the site of the inflating machine (2) and a calculated mean value for ambient temperature, pressures Pc and Pcc being given in absolute value and temperatures Tp and Tref being given in degree K.

Abstract: A battery powered tire pressure sensor system with a high sensitivity stretch sensor assembly having a variable resistance longitudinal displacement characteristic. The stretch sensor assembly has at least two juxtaposed stretch sensors, each with a first layer bearing the variable resistance element and a second support layer. The sensor assembly is mounted on or in the side wall of a pneumatic tire so that the assembly is displaced by the tire side wall and the resistance is a function of internal tire pressure. The assembly is coupled to a processor which samples the resistance of the stretch sensor assembly periodically. When the processor determines that the pressure is outside a safe range, an r.f. generator is activated by the processor to generate an unsafe tire pressure signal. This signal is converted by a receiver to a warning for the driver. A power saving unit controls application of electrical power to the system as a function of tire speed to prolong battery life.

Abstract: A tire pressure monitoring apparatus includes a pressure transducer having a housing and a valve stem secured to the housing. The valve stem projects through an opening in a wheel for holding the tire. A retention clip is secured to the valve stem. The retention clip includes a plurality of spring retention members for engaging the opening in the when the valve stem projects through the opening. The retention members are deflected when the valve stem projects through the opening and have resilient properties that spring bias the retention members against the wheel to help retain the tire pressure monitoring apparatus on the wheel.

Abstract: A single phase sampling apparatus and method for retrieving a formation fluid sample at or above the bubble point of the sample. The apparatus utilizes a gas charge contained between a sample piston and a charging piston to maintain a formation sample at the desired pressure. The charging piston utilizes the hydrostatic pressure present at the depth of the desired formation sample to compress and therefore increase the gas charge to the appropriate pressure necessary to maintain the formation sample at the desired pressure. The utilization of hydrostatic pressure to increase the pressure of the gas charge allows the use of a low pressure gas charging system to prepare the apparatus prior to sampling, thereby increasing the safety and ease of use of the device.

Abstract: A method and apparatus for estimating a property of a fluid downhole are disclosed. The apparatus includes a coated flexural resonator disposed in the downhole fluid. The resonator is coated to reduce effects of adhering surfactants suspended in the downhole fluid. The method uses the coated resonator to estimate a property of the downhole fluid.

Abstract: A real-time line management system and associated methods. A line management system for use in conjunction with an operation in a subterranean well includes a line installed in the well during the operation, and a computing device which indicates a used life of the line during the operation. A method of managing a line used in an operation in a subterranean well includes the steps of: installing the line in the well during the operation; and determining a used life of the line while the line is installed in the well. A method of managing a line used in multiple operations in one or more subterranean wells includes the steps of: estimating conditions which will be experienced by the line during a future operation; and predicting before the future operation what a used life of the line will be after the line is used in the future operation.

Abstract: A thermal mass flow meter for measuring flow rate of a fluid includes a conduit that is configured to receive the fluid and that defines a primary flow path between an inlet and an outlet of the conduit. The conduit is bound at least in part by a sensor receiving surface. A thermal sensor tube has a thermal sensing portion that is mounted relative to the sensor receiving surface in a direction substantially perpendicular to both the primary flow path and the sensor receiving surface. When the thermal mass flow meter is mounted in a vertical direction so that fluid within the conduit flows in the vertical direction along the primary flow path, fluid within the sensor tube flows in a horizontal direction so as to substantially prevent thermal siphoning when the sensor tube is heated.

Abstract: A chemical impedance detector having several electrodes situated on or across a dielectric layer of a substrate. The electrodes may be across or covered with a thin film polymer. Each electrode may have a set of finger-like electrodes. Each set of finger-like electrodes may be intermeshed, but not in contact, with another set of finger-like electrodes. The thin-film polymer may have a low dielectric constant and a high porous surface area. The chemical impedance detector may be incorporated in a micro fluid analyzer system.

Abstract: A thermal flow sensor can adjust the temperature of a heating element in a highly precise and reliable manner with the use of simple circuits, devices and process steps. The sensor includes an amplifier section (7) that amplifies a voltage across opposite ends of at least one of resistors (3, 4, 5) that constitute a bridge circuit, a current control section (9) that is controlled based on an output voltage of the amplifier section (7), and an output terminal (14) that is connected to one end of a heating element (1) that is controlled to be energized by the current control section (9). The amplifier section (7) includes an amplification factor control section for controlling an amplification factor by an electric signal from a computer, and uses an output voltage which has been amplified and impressed to an input voltage to an operational amplifier (8).

Abstract: A disclosed detector element includes a substrate including a void, a heating unit including a heat generating electrode bridged across the void, and a temperature sensor including a temperature sensor electrode provided above the void. The heat generating electrode and the temperature sensor electrode are warped, cantilevered, and standing up in space. The temperature sensor measures heat quantity transported from the heating unit. Distribution of an atmosphere surrounding an object surface with respect to the object surface, and the transportation state of the atmosphere are measured by using at least one of temperature, humidity, a direction or velocity of flow, pressure, and composition of gas in the atmosphere. Behavior of the gas adhering and aggregating onto the object surface, and behavior of aggregated liquid undergoing transpiration from the object surface are detected, based on the distribution and the transportation state measured.

Abstract: A battery and battery condition indicator are provided with a seal as monolithic structures whereby the indicator is inserted in an opening in the battery and sealed there against via ribs in the battery confronted by a surface of the indicator and/or ribs on the indicator embedded in a surface of the battery defining the opening.

Abstract: An improved apparatus and a method of measuring and interpreting reliably, simply and accurately the information on continuous liquid level, liquid temperature and other liquid properties within a vessel. The apparatus is suited for economical manufacturing and could be made of a powered heater element and temperature sensors that can be screen-printed, vacuum deposited, etched, welded, soldered or plated on one or both sides of a single rigid or a flexible substrate. The apparatus is compact and light weight and can be installed in relatively small liquid containers if necessary; Various parallel and serial configurations of thermocouples or temperature sensors can be used to measure the temperature along a heater. Simultaneous measurements from all the temperature sensors, before and after heat is applied, are used to generate accurate temperature profiles for the entire heater.

Abstract: A pump assembly for pumping a liquid and a method of controlling the pump assembly. The pump assembly includes a motor coupled to a pump, and an electronic switch assembly electrically connected to the motor to control the current through the motor. The electronic switch assembly includes an electronic switch, a generator that provides a substantially periodic pulsing signal, a circuit control configured to provide a second signal, and decision logic connected to the generator, the circuit control, and the electronic switch. The decision logic receives the periodic pulsing and second signals and generates a control signal that selectively controls the electronic switch based on the periodic pulsing and second signals.

Abstract: A humidity sensor includes: a sensor chip including a capacitive humidity sensor element and a connection electrode, wherein the capacitive humidity sensor element includes a humidity sensitive film having relative permittivity changeable in accordance with humidity, and wherein the connection electrode is electrically connected to the humidity sensor element; a lead plate electrically connected to the connection electrode; and a mold for covering a connection portion between the connection electrode and the lead plate. The mold is disposed on the sensor chip and includes a groove. The humidity sensitive film is disposed in the groove. The humidity sensitive film has a height in the groove, the height equal to or lower than a surface of the mold. The height of the humidity sensitive film in the groove is homogeneous.

Abstract: A sensor for sensing bioacoustic energy includes a housing comprising an interfacing portion configured to establish coupling with a body part during use of the sensor. An anchoring arrangement is defined on the housing. A transducer member has an anchoring end and at least one free end. The anchoring end of the transducer is coupled to the housing such that the transducer member is arranged to be preferentially sensitive to bioacoustic energy transferred to the transducer via the interfacing portion relative to other portions of the housing.

Abstract: A portable gauge and method are used to determine an as installed property of a loose-fill insulation in a building cavity wherein the cavity has a given depth, an open front, a rear surface, and sidewalls defined by spaced apart framing members. The gauge includes a frame for extending between and overlapping front surfaces of the framing members to position the gauge for determining an as installed property of the insulation; a plunger assembly mounted on the frame for compressing a portion of the insulation in the cavity to a compressed density sufficiently dense to prevent plunger creep and to a compressed thickness less than the as installed thickness of the insulation; and a readout assembly calibrated to indicate an as installed property of the insulation based on the compressed thickness of the insulation.

Abstract: A sensor for detecting an acceleration on a surface. The sensor exchanging messages with a computing means through a communication interface. The sensor comprises an accelerometer for outputting a signal representative of the acceleration and an interface unit comprising a transmitting circuit. The interface unit receives the signal representative of the acceleration and modulates the same for transmission to the computing means.

Abstract: A wireless position sensing wafer includes at least one accelerometer that measures acceleration along one direction. Integrating acceleration allows velocity and displacement from a starting point to be obtained. Orientation may be obtained from one or more gyroscopes or from a magnetic sensor. One or more artificial magnetic fields may be created for such a magnetic sensor. Position may also be found by triangulation with respect to fixed transmitters.

Abstract: A sensor for measuring acceleration in three mutually orthogonal axes, X, Y and Z is disclosed. The sensor comprises a sensor subassembly. The sensor subassembly further comprises a base which is substantially parallel to the X-Y sensing plane; a proof mass disposed in the X-Y sensing plane and constrained to move substantially in the X, Y, and Z, about by at least one linkage and is responsive to accelerations in the X, Y and Z directions. The sensor includes at least one paddle disposed in the sensing plane; and at least one pivot on the linkage. Finally, the sensor includes at least one electrode at the base plate and at least one transducer for each sensing direction of the sensor subassembly responsive to the acceleration.

Abstract: A sensor for sensing bioacoustic energy includes a housing comprising an interfacing portion configured to establish coupling with a body part during use. The sensor includes a transducer element coupled to the interfacing portion of the housing and configured to sense sounds produced by matter of biological origin. One or more conductors are coupled to the transducer element. A mass element is compliantly coupled to a surface of the transducer element. Intervening material is disposed between the transducer element surface and the mass element, and allows for differential motion between the transducer element surface and the mass element during excitation of the transducer element.

Abstract: Disclosed herein is a method and apparatus for generating an image of an article, wherein the image represents the articles elastic modulus. The method comprises the steps of measuring a time of flight value at a point on a test sample utilizing ultrasonic sound waves, measuring the position of the point, calculating a thickness value for the test sample, calculating a velocity value utilizing the time of flight value and the thickness value, calculating a density value for the test sample, calculating a Poisson's ratio value for the test sample, calculating an elastic modulus value utilizing the velocity value, the density value, and the Poisson's ratio value, assigning a shade of gray, or a color, to the elastic modulus values on the image, and, constructing an image utilizing the position of the point and the shaded, or colored, elastic modulus values.

Abstract: A system for providing an acoustic image that visually represents sound includes a light source, a liquid membrane, a sound source and a display device. Light from the light source is directed at one face of the liquid membrane as the sound source generates sound waves that are directed to the liquid membrane. The liquid membrane vibrates at resonant frequencies, changing the surface area of the liquid membrane. Light is reflected off of the liquid membrane as interference color, and captured as an image which provides a high fidelity translation of the audio signals that varies in pattern and color based on the audio signal.

Abstract: A shaker assembly for shaking a tested component. The shaker assembly permitting a vibration to be induced within the tested component, such as for use in measuring operating characteristics of the tested component.

Abstract: A surface acoustic wave pressure sensor includes: a substrate and at least one flexible membrane, suspended over a cavity defined in the thickness of the substrate, the membrane being elastically deformable by a pressure applied by a fluid and being defined between a first surface facing the cavity and a second opposite surface; a SAW device comprising a layer of piezoelectric material arranged on the second surface of the membrane, the SAW device further comprising at least one SAW electro-acoustic transducer formed on one free surface of the piezoelectric layer. The piezoelectric layer is formed by deposition of piezoelectric material on the membrane and the substrate is integrated in a chip of semiconductor material, the membrane being a layer of the chip suspended over the cavity.

Abstract: A pressure sensor for static and/or dynamic pressure measurement of a liquid, flowable, or gaseous medium is described, with a housing (2) and with a pressure measuring cell (3), on the side facing the medium an opening (4) being formed through which one side (5) of the pressure measuring cell (3) is directly or indirectly in contact with the medium to be monitored, and the pressure measuring cell (3) converting the pressure to be monitored into a proportional measurement signal by means of an electromechanical converter. The pressure sensor as claimed in the invention can have both a small outside diameter and can also be economically produced by the housing (2) sitting on the pressure measuring cell (3) and the housing (2) and the pressure measuring cell (3) being connected to one another on the face side so that the pressure measuring cell (3) is at least in part a component of the outer surface of the pressure sensor (1) and thus is not surrounded by the housing (2).

Abstract: A pressure sensor includes a sensor element having a sensing portion for generating a signal upon receiving a pressure, a pressure transmission member having one end attached to a sensing portion of the sensor element and a diaphragm having two sides that warp under application of the pressure. One side of the diaphragm serves as a pressure sensing surface for detecting the pressure applied thereon and another side serves as an attachment surface to be attached to another end of the pressure transmission member for transmitting the pressure to the sensing portion of the sensor element, and the diaphragm takes a shape of corrugation that has a plural number of bends formed therein.

Abstract: A micromechanical pressure sensor includes a substrate having a front side and a back side, the front side facing a medium and the back side being situated on the opposite side of the substrate. A sensor diaphragm having at least one sensor area is situated on the front side, and a recess or cavity is situated behind the sensor diaphragm, and electrical contacting is provided on the back side.

Abstract: A diaphragm structure with a first substrate including a first surface with an annular groove therein and a second opposing surface with an annular groove on each side of annular groove in the first surface defining a first diaphragm. A second substrate also includes a first surface with an annular groove therein and a second opposing surface with an annular groove on each side of the annular groove in the first surface defining a second diaphragm. A diaphragm overload stop is located behind the first and second diaphragms.