Pressure sensor assembly having protective pressure mechanism - Patents.com

Abstract

To provide a pressure sensor assembly that enables a desired level of protection from damage due to a transient fluid pressure event such as pressure spike.SOLUTION: A pressure sensor assembly 30 comprises a sensor body 32 having a sensitive film 46 in which fluid is connected to the sensitive film to determine the fluid pressure. A support body includes an opening connected to the body for receiving the fluid from an external source. The opening provides fluid flow communication with the sensitive film. In the pressure sensor, one or more channels 52 are arranged that are configured to reduce the transmission of a fluid pressure spike to the sensitive film. The channels are configured to have one or both of direction change and sections with different sizes.SELECTED DRAWING: Figure 2B

Description

[Technical field]

[0001] The pressure sensor assemblies disclosed herein relate to pressure sensors that include a sensor membrane or diaphragm in communication with a gas or fluid from an external source being monitored, and more particularly, to pressure sensors that offer an improved degree of protection from damage caused by transient fluid pressure events such as high pressure spikes. [Background technology]

[0002] The use of pressure sensor assemblies or pressure sensors to measure or monitor the pressure of a fluid from an external source with which the pressure sensor is in fluid flow communication is known in the art. A conventional pressure sensor assembly includes a diaphragm or membrane in contact with the fluid, the diaphragm or membrane configured to have a thin-walled structure for the purpose of converting the pressure of the fluid into a stress or displacement of the diaphragm under the fluid pressure. Typically, such pressure sensors have a port or opening for receiving fluid from an external source, the fluid is transferred to the diaphragm or membrane within the pressure sensor, and one or more sensing elements are connected to the diaphragm to measure or obtain data / receive a signal regarding the movement of the diaphragm, thereby determining the fluid pressure.

[0003] A problem with such conventional pressure sensors is that the fluid being measured may come from an external source that can generate high pressure transients, e.g., pressure spikes, which when transmitted to the pressure diaphragm or membrane, may be outside the design pressure range, thereby causing damage to the pressure diaphragm or membrane, i.e., the diaphragm or membrane may bend beyond its design yield point and permanently damage the pressure sensor.

[0004] In consideration of such problems, accessory devices, referred to in the art as snubber devices, have been developed and constructed as auxiliary devices placed between an external fluid source and a pressure sensor. Such snubber devices are in the form of a diaphragm, small orifice or restrictor, or free-moving tubing, and operate to attenuate the shock waves of a transient fluid pressure event to reduce or mitigate the shock waves before they enter the pressure sensor. However, because such auxiliary snubber devices are external devices, they add to the overall packaging cost and size of the pressure sensor and may not be suitable for end use applications where space for mounting an installed pressure sensor is scarce and at a premium, such as when used with a vehicle engine or powertrain member. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore desirable for a pressure sensor assembly to be constructed to provide a desired level of protection from damage due to transient fluid pressure events, such as pressure spikes, and further desirable for such a pressure sensor assembly to be constructed to provide such protection without increasing the overall size of the pressure sensor assembly for packing and placement purposes, thus avoiding the need for the external snubber devices or other external devices mentioned above. [Means for solving the problem]

[0006] The pressure sensor assemblies disclosed herein generally include a sensor body having a sensing membrane or diaphragm disposed within the body and a fluid communicated with the membrane for determining a pressure of the fluid. A support is connected to the body and includes an opening for receiving fluid from an external source, the opening being in fluid-flow communication with the membrane. One or more elements are disposed within the pressure sensor configured to mitigate transmission of fluid pressure spikes to the sensing membrane to protect the membrane from damage. In one example, one of the body or the support includes a channel for receiving and transmitting fluid from the opening to the membrane, and the channel itself can be configured to provide a desired protection from fluid pressure spikes, for example, the channel can include two or more directional changes in the body or support, or the channel can include one or more dimensional changes. In one example, a portion of the channel extends substantially transverse to one of the support opening and the sensing membrane. In one example, the channel has a series of two or more directional changes of about 45 to 150 degrees each. In one example, the channel includes one or more different sized sections interposed between the support opening and the membrane. The channel can be integral with one or both of the sensor body and the support, and can be disposed within one or both of the sensor body and the support. In an exemplary embodiment, the channel can be in fluid flow communication with an internal chamber or cavity disposed within the body and / or support configured to assist in providing the desired protection from fluid pressure spikes. In one example, the pressure sensor is in the form of a MEMS sensor, the sensor body is formed from silicon and includes an internal chamber, the sensing membrane is disposed at one end of the chamber, and the support is formed from a material selected from the group consisting of silicon and glass. In one example, the pressure sensor includes one or more electrical sensing elements coupled to the membrane to determine fluid pressure from movement of the membrane.

[0007] A method of mitigating pressure spikes in a fluid being monitored by a pressure sensor assembly disclosed herein includes receiving the fluid to be monitored into an opening in a sensor assembly support. The fluid is transferred from the support to a sensor body comprising an internal chamber and a sensing membrane, the sensing membrane being in fluid communication with the fluid. Before being transferred to the sensing membrane, the fluid is treated to reduce the magnitude of pressure spikes in the fluid and protect the sensing membrane from damage. Such treatment may include routing the fluid through a channel disposed in one of the support or the body and interposed between the opening and the sensing membrane. The channel may be configured as described above and / or may be in fluid flow communication with a second internal chamber or cavity to assist in reducing the magnitude of the fluid pressure spikes.

[0008] The pressure sensor assembly disclosed herein will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional side view of a prior art pressure sensor assembly. [Figure 2A] FIG. 2 is a side cross-sectional view of an exemplary pressure sensor assembly disclosed herein. [Figure 2B] FIG. 2 is a top cross-sectional view of an exemplary pressure sensor assembly disclosed herein. [Figure 3A] FIG. 2 is a side cross-sectional view of an exemplary pressure sensor assembly disclosed herein. [Figure 3B] FIG. 2 is a top cross-sectional view of an exemplary pressure sensor assembly disclosed herein. [Figure 4] 1 is a cross-sectional side view of an exemplary pressure sensor assembly disclosed herein. [Diagram 5] 1 is a cross-sectional side view of an exemplary pressure sensor assembly disclosed herein. [Figure 6] 1 is a cross-sectional side view of an exemplary pressure sensor assembly disclosed herein. [Figure 7]1 is a cross-sectional side view of an exemplary pressure sensor assembly disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of a pressure sensor assembly will be described in detail with reference to the accompanying drawings, in which like reference numerals refer to like elements. However, the pressure sensor assembly or pressure sensor disclosed herein may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the pressure sensor assembly to those skilled in the art.

[0011] The pressure sensor assembly or pressure sensor disclosed herein generally comprises a sensor body connected to a support or substrate, one of which is specially designed to include an integral feature or element in the form of a channel configured to mitigate shock waves resulting from transient fluid pressure events of a fluid entering the pressure sensor for pressure measurement / monitoring. In one example, the pressure sensor disclosed herein is configured in the form of a microelectromechanical system (MEMS) pressure sensor for monitoring or measuring the pressure of a fluid in an external device and sending a pressure signal to a remote device such as a controller, processor, etc. A feature of the pressure sensors disclosed herein is that they are constructed with built-in / integral fluid shock mitigation mechanisms, thereby obviating the need to use external snubbers and the like, and the associated deficiencies discussed above. It should be appreciated that the pressure sensor assemblies disclosed herein can be used in gas or fluid service. A further feature of such assemblies is that they can be constructed to help protect against damage that may be caused by particles present in the fluid that could otherwise reach the membrane directly.

[0012] 1 shows a prior art MEMS pressure sensor 10 comprising a silicon sensor body 12 that is mounted or otherwise bonded by conventional methods along a bottom surface 14 to a glass support or substrate 16. The support 16 is configured such that attachment of the pressure sensor to an external fluid source can be easily monitored or measured using a further assembly or housing (not shown) configured to enhance such intervening attachment. This example includes a top cover 18 formed from glass that is attached or otherwise joined by conventional methods to a top surface 20 of the sensor body 12. The sensor body includes an interior chamber 22 and a membrane or diaphragm 24 disposed along one end of the interior chamber that is configured to move in response to application of fluid pressure thereto.

[0013] Fluid from an external source enters the pressure sensor 10 through a fixed diameter opening 26. The opening 26 passes through the support 16 and provides continuous, unobstructed fluid flow communication with the internal chamber 22 of the sensor body. Changes in pressure of the fluid entering the pressure sensor cause a membrane or diaphragm 24 to move. The top cover 18 contains a chamber 28 that provides a known reference volume, and movement of the diaphragm or membrane due to changes in fluid pressure causes changes in the reference volume, and these changes are monitored and measured to determine the fluid volume pressure therefrom. Such pressure sensors include an electrical pressure sensing element, such as a piezo-resistive element, that can be connected to the membrane or other portions of the sensor to provide an output signal in response to changes in a property of the sensor in response to fluid pressure.

[0014] Such prior art MEMS pressure sensors, as shown in Figure 1, include a sensing diaphragm or membrane that is designed to operate within defined ranges of fluid pressure and yield conditions for the diaphragm or membrane. If the fluid pressure experienced by the pressure sensor falls outside of the defined range of conditions, such as during a transient high fluid pressure event or spike, the diaphragm or membrane may tear or otherwise be damaged, thereby rendering the pressure sensor unusable. In such prior art pressure sensors 10, fluid entering the pressure sensor passes through an opening 26 in the substrate directly into the interior chamber 22 of the pressure sensor and into contact with the diaphragm or membrane 24. Although there is a slight increase in the volume moving from the opening in the substrate to the internal chamber of the sensor body, such volume change is not sufficient to mitigate or offset the impact effects on the diaphragm from such a transient high pressure fluid spike. As briefly mentioned above, to address such limitations of prior art pressure sensors, external snubber devices have been used, such snubbers being interposed between an external fluid source and a MEMS pressure sensor.

[0015] 2A and 2B show an exemplary pressure sensor assembly or pressure sensor 30 disclosed herein. In one example, the pressure sensor is a MEMS sensor comprising a sensor body 32 and a substrate or support 34 attached or bonded to the sensor body along a lower surface 36 of the sensor body. In one example, the sensor body can be formed from silicon, for example provided as a silicon wafer of single crystal silicon or other suitable forms of silicon. The support 34 can be formed from a material having a similar coefficient of thermal expansion to the material used to form the sensor body. In one example, the support can be selected from a group including silicon or other materials such as glass or PYREX that are chemically inert and can be bonded to the sensor body. In one example, the support 34 is formed from glass.

[0016] The pressure sensor 30 includes a top cover or upper support 38, which may be formed from the same types of materials as the support 34 described above, and is attached or bonded to the sensor body along an upper surface 40. The upper support 38 includes an internal chamber 42 configured to provide a reference volume. The sensor body 32 includes an internal chamber 44 that extends within the body from an interface with the support 34 to a sensing diaphragm or membrane 46 positioned at an opposite end of the internal chamber. The diaphragm or membrane 46 is configured to move in response to application of fluid pressure to the diaphragm or membrane when a fluid is placed within the internal chamber 44. In an exemplary embodiment, the internal chamber 44 is configured to have a conical shape that decreases in diameter moving from the lower surface 36 of the body to the diaphragm or membrane 46.

[0017] The support 34 includes a fluid opening 47 disposed through a thickness of the support defined between a support bottom surface 48 and a support top surface 50 attached to the sensor body 32. The opening 47 in the support may be formed by conventional methods such as machining, etching, molding, and the like. In this example, the opening 47 has a continuous diameter, but it should be understood that the opening may also be configured to have a variable diameter if desired. Moving towards the sensor body 32, the opening 47 is in fluid flow communication with a fluid inlet port 51 of the sensor body positioned at the top of the opening 47. In one example, the inlet port 51 may also be configured to complement an opening having approximately the same diameter as the diameter of the opening 47, for example.

[0018] As best shown in FIG. 2B , the sensor body includes a pressure relief element in the form of a channel 52 that extends from one end 53 in fluid flow communication with the port 51 to another end 54 in fluid flow communication with the interior chamber of the sensor body and the sensing membrane 46. In one example, the channel 52 is integral with the sensor body and includes two or more direction changes within the sensor body. In one example, the channel includes a series of distinct sections, each section having a departure angle relative to an adjacent section. In one example, such departure angle may be approximately 90 degrees. However, it should be understood that the configuration of the channel sections and the approximate departure angles of such sections relative to one another may be varied as needed by a particular end use application.

[0019] In one example, the channel is configured to provide a desired relief, reduction, or elimination of transient fluid pressure effects, such as pressure spikes, to protect the diaphragm or membrane from damage during use. In the particular example shown in FIG. 2B, the channel 52 is configured to have a diameter smaller than the diameter of the opening 47 to help provide the desired relief of such transient fluid pressure effects. In one example, the channel 52 can have a cross-sectional area that is approximately 10 percent smaller than the opening 47. The opening 47 is larger in size to allow for alignment to be achieved to account for tolerances of the die to be mounted in the ported package.

[0020] In this exemplary embodiment, the channel 52 includes approximately five sections extending between the port 51 and the internal chamber 44, with a first section 55 being straight and extending within the sensor body in a direction parallel to a first edge 56 of the body adjacent the first edge 56 to a tangent point with a second section 57. The second channel section has a departure angle of approximately 90 degrees relative to the first section and extends in a direction parallel to a second edge 58 of the body adjacent the second edge 58 to a tangent point with a third section 60. The third channel section has a departure angle of approximately 90 degrees relative to the second section and extends in a direction parallel to a third edge 62 of the body opposite the first edge 56 to a tangent point with a fourth section 64 adjacent the third edge 62. The fourth channel section has a departure angle of approximately 90 degrees relative to the third section and extends in a direction parallel to a fourth edge 66 of the body opposite the second edge 58 adjacent to the fourth edge 66 to a tangent point with a fifth section 67. The fifth channel section has a departure angle of approximately 90 degrees relative to the fourth section and extends in a direction parallel to the first edge 56 and the third edge 62 of the body to the internal chamber of the sensor body. Channel 52 configured in this manner extends within the sensor body from port 51 around the internal chamber to a junction with the internal chamber to mitigate transient fluid pressure events and protect the diaphragm and membrane from undesired damage. In one example, the length of this channel is optimized for a particular end use application, as a longer channel provides a slower response but further mitigates pressure spikes.

[0021] A feature of this example pressure sensor 30 is that the channel 52 is an integral part of the sensor body 32, which may be formed in the sensor body by machining processes, etching processes, deposition processes, etc. Although the channel 52 of this example pressure sensor 30 has been described and disclosed as having a constant diameter and multiple interconnected sections, it should be understood that the channel may also be configured to have one or more sections or segments of different diameters, such as one or more channel sections having a larger or smaller diameter than other sections.

[0022] Additionally, while the channel sections in this embodiment have been described as having a 90 degree departure angle relative to adjacent sections, it should be understood that the departure angle may vary. For example, the departure angle between different adjacent sections or segments of the channel may be between 45 and 150 degrees and between 60 and 120 degrees, depending on the particular pressure sensor configuration and end use application. Additionally, as best shown in FIG. 2B, in this example, the channel 52 and its sections are oriented within the sensor body along a single plane parallel to the lower surface 36. It should be understood that the channel may also be oriented differently within the body as required by a particular end use application or structural configuration.

[0023] The MEMS pressure sensors disclosed herein, including the examples disclosed above, can be configured for use with a conventional sensing diaphragm or membrane, or a reference volume measuring element, such as a piezo-resistive element, a piezoelectric conductive element, a contact element, etc., as needed for a particular end use application. In an exemplary embodiment, the MEMS pressure sensor 30 can be configured for use with a piezo-resistive element to detect movement of the diaphragm or membrane and / or changes in the reference volume. Although the example MEMS pressure sensor shown in Figures 2A and 2B shows the use of a top support and a reference volume, such use can be optional for the MEMS pressure sensors disclosed herein.

[0024] 3A and 3B illustrate an exemplary pressure sensor assembly or pressure sensor 80 disclosed herein. In one example, the pressure sensor is a MEMS pressure sensor comprising a sensor body 82 and a substrate or support 84 attached or bonded to the sensor body along a bottom surface 86 of the sensor body. In one example, the sensor body and support can be formed from the same types of materials as described above with respect to the previous pressure sensor examples. The pressure sensor 80 includes a top cover or upper support 88, which can be formed from the same types of materials as the support 84 described above, attached or bonded to the sensor body along a top surface 90.

[0025] The upper support 88 includes an interior chamber 92 configured to provide a reference volume. The sensor body 82 includes an interior chamber 94 that extends within the body from an interface with the support 84 to a sensing diaphragm or membrane 96 positioned at an opposite end of the interior chamber. The diaphragm or membrane 96 is configured to move in response to fluid pressure exerted on the diaphragm or membrane when a fluid is placed within the interior chamber 94. In an exemplary embodiment, the interior chamber 94 is configured to have the conical shape described above.

[0026] The support 84 includes a fluid opening 98 that extends a portion of the way from the support bottom surface 100 to receive external fluid into the pressure sensor. The opening 98 can be formed by conventional methods such as machining, etching, molding, and the like. In this example, the opening 98 has a continuous diameter and extends a portion of the way into the support. The exact depth of the opening can vary depending on the particular end use application and can be about 10-90 percent, about 20-60 percent, and about 30-50 percent of the overall support thickness. In an exemplary embodiment, the opening 98 extends a depth of about 15 percent of the overall support thickness. Although the fluid openings in the support have been described as having a constant diameter, it should be understood that the openings can be configured to have variable diameters, if desired.

[0027] In contrast to the pressure sensor shown in FIGS. 2A and 2B, a feature of this exemplary pressure sensor 80 is that a pressure relief element or channel for mitigating undesirable transient fluid pressure effects is disposed within the support 84 rather than the sensor body 82. The support 84 thus includes a channel 110 extending from one end 112 in fluid flow communication with the opening 98 to another end 114 in fluid flow communication with the interior chamber 94 of the sensor body. In one example, the channel 110 is integral with the support 84 and includes two or more direction changes within the support. In one example, the channel 110 includes a series of distinct sections, each section having a departure angle relative to an adjacent section. In one example, such departure angle may be approximately 90 degrees. However, it should be understood that the configuration of the channel sections and the approximate departure angles of such sections relative to one another may be varied as needed depending on the particular end use application discussed above.

[0028] In one example, the channel 110 is configured to provide a desired mitigation, reduction, or elimination of transient fluid pressure effects, such as pressure spikes, to protect the diaphragm or membrane from damage during use. In the particular example shown in Figures 3A and 3B, the channel 110 is configured to have a diameter smaller than the diameter of the opening 98 to help provide a desired mitigation of such transient fluid pressure effects. In one example, the channel 110 can have a diameter of the size discussed above with respect to the example pressure sensor of Figures 2A and 2B.

[0029] The channel 110 includes approximately eight sections extending between the opening 98 and the interior chamber 94 of the sensor body, with a first section 120 being straight and extending within the support 84 in a direction parallel to a first edge 122 of the support to a tangent point with a second section 124. The second channel section 124 has a departure angle of approximately 90 degrees relative to the first section and extends in a direction parallel to a second edge 126 of the support to a tangent point with a third section 128. The third channel section 128 has a departure angle of approximately 90 degrees relative to the second section and extends in a direction parallel to the first edge 122 of the support adjacent the first edge 122 to a tangent point with a fourth section 130. The fourth channel section 130 has a departure angle of approximately 90 degrees relative to the third section and extends in a direction parallel to a third edge 132 of the support opposite the second edge adjacent the third edge 132 to a tangent point with a fifth section 134. The fifth channel section 134 has a departure angle of about 90 degrees relative to the fourth section and extends in a direction parallel to the fourth edge 136 of the support adjacent the fourth edge 136 to a tangent point with a sixth section 138. The sixth channel section 138 has a departure angle of about 90 degrees relative to the fifth section and extends in a direction parallel to the second edge 126 and the third edge 132 of the support to a tangent point with a seventh section 140. The seventh channel section 140 has a departure angle of about 90 degrees relative to the sixth section and extends in a direction parallel to the first edge 122 of the support to a tangent point with an eighth section 142. The eighth channel section 142 has a departure angle of about 90 degrees relative to the seventh section and extends in a direction parallel to the second edge 126 and the third edge 132 of the support to a tangent point with the sensor body interior chamber 94.

[0030] As shown, the channels 110 are oriented within the support 84 in a pattern that moves concentrically around the sensor body's internal chamber 94 and inwardly toward the sensor body's internal chamber 94. In addition, Figure 3A shows that the channels 110 move upwardly from the fluid openings 98 the depth of the support 84 to the sensor body's underside 86 and into the sensor body's internal chamber 94. The channels 110 configured in this manner extend within the support 84 from the openings 98 to a contact point with the internal chamber to mitigate transient fluid pressure events and protect the diaphragm and membrane from undesired damage.

[0031] A feature of this example pressure sensor 80 is that the pressure relief element or channel 110 is an integral part of the support 84, which may be formed in the support by machining processes, etching processes, deposition processes, etc. Although the channel 110 of this example pressure sensor 80 has been described and disclosed as having a constant diameter and multiple interconnected sections or segments, it should be understood that the channel may also be configured to have one or more sections of different diameters, for example, one or more channel sections having a larger or smaller diameter than other sections. Additionally, while the channel sections in this embodiment have been described as having a 90 degree departure angle relative to adjacent sections, it should be understood that the departure angle may vary, as discussed above.

[0032] While the exemplary pressure sensors shown in Figures 2A, 2B, 3A, and 3B discussed above relate to pressure sensors having a diaphragm or membrane positioned at one end of an inner chamber disposed within a sensor body, it should be understood that the pressure sensor assembly comprising mechanisms and elements that operate to mitigate transient fluid pressure events and protect the diaphragm or membrane from damage as described herein is not intended to be limited to one particular pressure sensor structure.

[0033] 4 illustrates an exemplary pressure sensor assembly 150 in the form of a buried cavity pressure sensor comprising a sensor body 152 attached or bonded to a support 154, which may be formed from the same types of materials discussed above. In this example, a membrane or diaphragm 156 is interposed at a body-to-support interface 158, the body 152 is configured to have an internal chamber or cavity 160 above the membrane 156, and the support 154 is configured to have an internal chamber or cavity 162 below the membrane. The body's internal cavity 160 is configured to receive a volume of fluid from an external source for pressure monitoring and / or measurement, and the support's internal cavity 162 is configured to house a reference volume and / or element for measuring changes in the membrane's motion caused by contact with the fluid being monitored.

[0034] The support has an opening 164 that extends the thickness of the support from the lower surface 166 to the interface 158 with the body. In this example, the opening 164 has a constant diameter and is straight. The sensor body 152 includes a pressure relief element in the form of a channel 168 positioned in fluid flow communication with the opening 164 and the internal cavity 160 of the body, the channel 168 including two sections, a first section 170 that extends part way through the body from the opening 164, and a second section 172 that connects to and extends from the first section and has a departure angle of approximately 90 degrees relative to the first channel section 170. Thus, a feature of this example pressure sensor is the inclusion of a channel 168 integral with the sensor body 152 that changes direction in a manner calculated to relieve fluid pressure events and protect the membrane 156 from damage.

[0035] 5 illustrates an exemplary pressure sensor assembly 180 in the form of a buried cavity sensor comprising a sensor body 182 attached or bonded to a support 184, which may be formed from the same types of materials as discussed above. In this example, a membrane or diaphragm 186 is interposed at a body-to-support interface 188, with the body 182 configured to have an internal chamber or cavity 190 above the membrane 186 and the support 184 configured to have an internal chamber or cavity 192 below the membrane, each provided for the same reasons as discussed above with reference to the exemplary pressure sensor of FIG.

[0036] Unlike the exemplary pressure sensor of FIG. 4, an opening 194 for receiving fluid from an external source is provided in the sensor body, which opening extends a portion of the way from a top surface 196 of the body. A pressure relief element in the form of a channel 198 is in fluid flow communication with the opening 194, extends from the opening 194 to an internal cavity 190 of the sensor body, and is integral with the body. In one example, the channel 198 includes three sections. A first channel section 200 extends a distance from the opening 194 parallel to the top surface 196 to a second section 210, which has a departure angle of about 90 degrees relative to the first section. The second section 210 extends downwardly perpendicular to the top surface into the body and connects to a third section 212, which has a departure angle of about 90 degrees relative to the second section. The third channel section 212 extends parallel to the top surface 196 a distance into the interior cavity 190 of the body. Thus, a feature of this example pressure sensor is that it includes a channel that is integral with the sensor body and that changes direction in a manner calculated to mitigate fluid pressure events and protect the membrane 186 from damage.

[0037] 6 illustrates an exemplary pressure sensor assembly 300 comprising a sensor body 302 attached or bonded to a support 304, where the sensor body and support can be formed from the same types of materials discussed above. In this example, a diaphragm or membrane 306 can be formed from the sensor body, with a horizontal cavity 308 disposed immediately below the diaphragm, with a lower surface portion of the diaphragm in fluid flow communication with the fluid entering the horizontal cavity 308. The sensor body includes a pressure relief element in the form of a vertical channel 310 that extends through the body from the horizontal cavity 308 to a section 312 of the body that interfaces with the support. In one example, the section 312 can be configured in the form of a horizontal channel or cavity positioned adjacent the interface between the body and the support.

[0038] In this example, adjacent boundary sections of body 302 and support 304 are each formed with a horizontal channel or cavity member which together form another pressure relief element in the form of horizontal channel or cavity 316, in one example a horizontal channel or cavity having an enlarged volume compared to vertical channel 310. In this example, a further pressure relief element in the form of vertical channel 318 is in fluid flow communication with horizontal channel or cavity 316 and extends from horizontal channel or cavity 316 through support 304 to an opening 320 located along a bottom surface 322 of the support to receive incoming fluid. In one example, the locations where the vertical channels 310 of the body and the vertical channels 318 of the support connect to the horizontal channels can be offset in conjunction with the increased volume of the horizontal channels to further mitigate fluid pressure events and protect the diaphragm 306 from damage.

[0039] Although the illustrated example shows the horizontal channel or cavity 316 as being formed from adjacent boundary sections of both the body and the support, it should be understood that the horizontal channel or cavity can also be formed within one section of the body or support while providing the same desired functions and advantages. Although not shown in FIG. 6, the pressure sensor assembly 300 can include a top cover or upper support as disclosed above in other examples.

[0040] 7 illustrates an exemplary pressure sensor assembly 400 comprising a sensor body 402 attached or bonded to a support 404, which may be formed from the same types of materials as discussed above. The pressure sensor assembly 400 includes a top cover or upper support 406, which may be formed from the same types of materials as the support 404 described above, attached or bonded to the sensor body along a top surface 408. The upper support 406 includes an interior chamber 410 configured to provide a reference volume. The sensor body 402 includes an interior chamber 412 that extends within the body from an interface with the support 406 to a sensing diaphragm or membrane 414 positioned at an opposite end of the interior chamber. In an exemplary embodiment, the interior chamber 412 is configured to have a conical shape, as described above.

[0041] The support 404 includes a fluid inlet channel 416 extending inwardly from a bottom surface 418 to a partial depth for receiving a fluid. The inlet channel extends to and is in fluid flow communication with a pressure relief element in the form of an internal cavity or chamber 420 having an enlarged diameter and volume relative to the inlet channel 416. Disposed within the internal chamber 420 is another pressure relief element in the form of a member 422, for example a piston, constructed and formed from a material that allows it to move within the internal chamber in response to pressure spikes in the fluid entering from the inlet channel 416. The support further includes a fluid outlet channel 424 that extends to and is in fluid flow communication with a portion of the internal chamber opposite the inlet channel 416. An outlet channel 424 extends from the interior chamber to the interface between the body and the support and is positioned above and in fluid flow communication with the interior chamber 412 of the sensor body. In one example, the fluid inlet channel 416 is positioned such that fluid entering the support contacts a member 422 disposed within the internal chamber 420, and the fluid outlet channel 424 is positioned such that movement of the member 422 within the internal chamber in response to a spike in fluid pressure causes the member to block fluid flow to the fluid outlet and the sensor body. A feature of the pressure sensor assemblies disclosed herein is that one or more pressure relief elements, e.g., one or more channels, are configured as an integral part of the pressure sensor assembly itself, and such one or more elements are specially configured such that they can operate independently or in conjunction with one another within the pressure sensor assembly to mitigate transient fluid pressure events and protect the diaphragm or membrane from damage during operation of the pressure sensor.

Claims

1. a sensor body (32) including a sensing membrane (46), the sensing membrane (46) disposed within the sensor body in fluid communication with the membrane for determining a pressure of a fluid; a support (34) connected to the sensor body (32) and having an opening (47) for receiving the fluid from an external source, the opening being in fluid flow communication with the sensing membrane (46); one of the sensor body (32) or the support (34) comprises a channel (52) for receiving the fluid from the opening and transmitting it to the sensing membrane (46), the channel (52) being configured to have one or both of a change in direction and sections of different size to mitigate transmission of pressure spikes to the sensing membrane (46); The channel (52) is provided surrounding the sensing membrane (46). A pressure sensor assembly (30).

2. The pressure sensor assembly (30) of claim 1, wherein at least a portion of the channel (52) extends substantially transverse to one of the opening (47) in the support and the sensing membrane (46).

3. The pressure sensor assembly (30) of claim 1, wherein the channel (52) includes two or more different sized sections (55) interposed between the opening (47) in the support and the membrane (46).

4. The pressure sensor assembly (30) of any preceding claim, wherein the channel (52) has a series of two or more directional changes of approximately 45 to 150 degrees each.

5. The pressure sensor assembly (30) of claim 1, wherein the channel (52) includes at least two directional changes and includes one or more different sized sections.

6. 2. The pressure sensor assembly (30) of claim 1, in the form of a MEMS sensor, the sensor body (32) being formed from silicon and having an internal chamber (44), the sensing membrane (46) being disposed at one end of the internal chamber (44), and the support (34) being formed from a material selected from the group consisting of silicon and glass.

7. a sensor body (32) formed from silicon, the sensor body (32) including an interior chamber (44) disposed within the sensor body (32) and a membrane (46) located at one end of the interior chamber, the sensor body having an interface (36) opposite the membrane; an electrical sensing element connected to the membrane for determining a pressure of a fluid entering the sensor body and contacting the membrane; a support (34) attached to the boundary surface (36) of the sensor body and having an opening (47) for receiving a fluid to be transferred to the sensor body (32); a pressure relief element (52) disposed between the opening (47) and the membrane (46), the pressure relief element (52) being integral with the MEMS pressure sensor (30), the pressure relief element comprising a channel having one or more directional changes within the MEMS pressure sensor; The channel (52) is disposed surrounding the membrane (46).

8. The MEMS pressure sensor (30) of claim 7, wherein the channel (52) includes two sections (55) and (57) oriented approximately 90 degrees apart from one another.

9. The MEMS pressure sensor (30) of claim 7, wherein the channel (52) includes a section (55) of a different size than the opening.

10. The MEMS pressure sensor of claim 7, wherein the channel is disposed within the sensor body and includes two or more directional changes of about 90 degrees or greater.

11. 8. The MEMS pressure sensor of claim 7, wherein the channel extends around an exterior periphery of the interior chamber and includes a termination that enters an axial end of the interior chamber opposite the membrane.

12. 1. A method for mitigating pressure spikes in a fluid being monitored by a pressure sensor assembly (30), comprising: Receiving a fluid to be monitored into an opening (47) in a sensor assembly support (34); transmitting the fluid from the sensor assembly support (34) to a sensor body (32) attached to the sensor assembly support (34), the sensor body (32) comprising an internal chamber (44) and a sensing membrane (46) connected to the internal chamber (44), the sensing membrane (46) in communication with the fluid; and processing the fluid within the pressure sensor assembly (30) to reduce the magnitude of pressure spikes in the fluid and protect the sensing membrane (46) from damage, the processing comprising routing the fluid through a pressure relief element (52) disposed within the sensor between the opening (47) and the sensing membrane (46) and surrounding the sensing membrane (46).

13. 13. The method of claim 12, wherein the pressure relief element is a channel (52) integral with the sensor body (32) or the sensor assembly support (34), and during the treating step, the fluid is directed through the channel (52) within the sensor body or the sensor assembly support in a direction substantially transverse to one of the opening (47) of the sensor assembly support and the sensing membrane (46) to reduce the magnitude of pressure spikes in the fluid before it reaches the sensing membrane (46).

14. The method of claim 12, wherein during the processing step, the fluid is directed through the channel (52) to make two or more directional changes of about 45 to 150 degrees each.

15. 13. The method of claim 12, wherein the pressure relief element is a channel (52) integral with the sensor body (32) or the sensor assembly support (34), and during the processing step, the fluid is directed through one or more differently sized sections of the channel (52) having an enlarged volume relative to other sections of the channel to reduce the magnitude of pressure spikes in the fluid before it reaches the sensing membrane (46).

Images