Pressure Sensor Assembly with a Protective Pressure Mechanism

Abstract

To provide a pressure sensor assembly that provides a desired level of protection from damage due to pressure spike or the like.SOLUTION: A support body 40 is connected to a main body 32 and a substrate 72 is connected to the support body 40. The support body 40 includes a channel 44 and the substrate 72 includes a channel 76 for receiving fluid from an external source and guiding the fluid to a film 36. To reduce the transmission of a pressure spike from external fluid entering an opening 84 in a substrate base member 82, a pressure reduction element is arranged on one or both of the support body 40 and the substrate 72. In one example, the pressure reduction element has chambers 88 and 92 and a channel 90 in a substrate wall member 78.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The pressure sensor assembly disclosed herein relates to a pressure sensor having a sensor diaphragm or diaphragm in communication with a gas or fluid from a monitored external source, and more particularly to a pressure sensor that provides an improved degree of protection from damage caused by transient fluid pressure events such as high pressure spikes.

Background Art

[0002] The use of a pressure sensor assembly or pressure sensor for measuring or monitoring the pressure of a fluid from an external source in fluid flow communication is known in the art. Conventional pressure sensor assemblies include a diaphragm or membrane that contacts the fluid, and the diaphragm or membrane is configured to have a thin wall structure for the purpose of converting the pressure of the fluid into stress or displacement of the diaphragm when fluid pressure is applied. Typically, such a pressure sensor has a port or opening for receiving fluid from an external source, the fluid is transmitted to the diaphragm or membrane within the pressure sensor, and one or more sensing elements are connected to the diaphragm to measure or acquire data regarding the movement of the diaphragm / receive a signal, thereby determining the fluid pressure.

[0003] A problem associated with such conventional pressure sensors is that the fluid being measured can come from an external source capable of generating high pressure transient events, such as pressure spikes, and such pressures, when transmitted to the pressure diaphragm or membrane, can be outside the design pressure range, thereby potentially causing damage to the pressure diaphragm or membrane, i.e., the diaphragm or membrane may bend beyond its design yield point, potentially permanently damaging the pressure sensor.

[0004] In view of such problems, an accessory device called a snubber device has been developed in the art and has been constructed as an auxiliary device disposed between an external fluid source and a pressure sensor. Such a snubber device is in the form of a diaphragm, a small orifice or restrictor, or a freely moving pipe member, and operates to reduce or attenuate the shock wave of a transient fluid pressure event before entering the pressure sensor. However, since such an auxiliary snubber device is an external device, it increases the overall packaging cost and size of the pressure sensor, and may not be suitable for end-use applications where space for installing the installed pressure sensor is scarce and valuable, such as when used with a vehicle engine or power train member. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] Accordingly, it is desirable to construct a pressure sensor assembly to provide a desired level of protection from damage due to transient fluid pressure events, such as pressure spikes. Further, such a pressure sensor assembly is constructed to provide such protection without increasing the overall size of the pressure sensor assembly for packaging and placement purposes and to avoid the need for the external snubber device or other external devices described above. Further, such a pressure sensor assembly is constructed to reduce the difference in thermal expansion coefficient characteristics that exists between the sensor and an external device to which the sensor is connected, such as a device that transmits external fluid for pressure sensing. MEANS FOR SOLVING THE PROBLEMS

[0006] The pressure sensor assembly disclosed herein generally comprises a sensor body with a sensing membrane, which communicates fluid from an external source with the membrane and is disposed within the body to determine the pressure of the fluid. The sensor assembly further comprises a support connected to the body, the support having a channel extending therethrough for receiving fluid, the channel being in fluid flow communication with the membrane. A substrate is connected to the support, the substrate having a channel extending therethrough for receiving fluid from an external source, the fluid being transmitted through the substrate to the support. In one example, the support is formed from a material having a coefficient of thermal expansion between that of the support and that of an external fluid source connected to the substrate. In one example, the sensor body is formed from silicon and the substrate is formed from a ceramic material. One of the channels of the substrate or of the support comprises a pressure reduction element or mechanism for reducing the transmission of gas or fluid pressure spikes from the external source to the sensor membrane. In one example, the substrate comprises several ceramic elements joined together to form a pressure reduction mechanism. In one example, the pressure reduction mechanism comprises a volume expansion portion. In one example, the pressure reduction mechanism comprises a movable member disposed in the channel. In one example, the pressure reduction mechanism comprises a porous member disposed in the channel. In one example, the pressure reduction mechanism includes two or more directional changes of the channel when moving through the support or the substrate. In one example, the pressure sensor assembly can further comprise a printed circuit board connected to the substrate.

[0007] A method of reducing pressure spikes of an external fluid monitored by the pressure sensor assembly disclosed herein can include inducing fluid from an external source into a substrate having a channel extending therethrough. The fluid is then transmitted from the substrate to the sensor body, where the fluid enters the sensor body and contacts the membrane. In one example, a support is interposed between the sensor body and the substrate. The high pressure spikes of the fluid within the pressure sensor assembly are reduced by inducing the fluid to pass through a pressure reduction mechanism positioned within the pressure assembly and upstream of the sensor body membrane.

[0008] The pressure sensor assembly disclosed in this specification will be described below as an example with reference to the accompanying drawings.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the pressure sensor assembly will be described in detail with reference to the accompanying drawings. In the accompanying drawings, like reference numerals refer to like elements. However, the pressure sensor assembly or pressure sensor disclosed in this specification can be implemented in many different forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete and to 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 and a substrate, and one or more of the support or the substrate of the sensor assembly are specially designed to include an integral pressure relief element or mechanism in the form of a channel or the like configured to reduce shock waves caused by transient gas or fluid pressure events of the 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 that monitors or measures the pressure of the fluid of an external device and sends a pressure signal to a remote device such as a controller or a processor. The pressure sensor disclosed herein is constructed to include a built-in / integral fluid shock mitigation mechanism, thereby preventing the need to use external snubbers or the like and avoiding the above-described drawbacks associated therewith. It should be understood that the pressure sensor assembly disclosed herein can be used in gas or fluid services. A further feature of such an assembly is that it 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] FIG. 1 shows a prior art MEMS pressure sensor 10 comprising a silicon sensor body 12, which is attached or otherwise joined to a glass support 16 along a bottom surface 14 by conventional methods. The support 16 is configured such that the attachment of the pressure sensor to an external fluid source can be readily monitored or measured using a further assembly or housing (not shown) configured to reinforce such an intervening attachment. This example includes a top cover 18 formed from glass, which is attached or otherwise joined to the upper surface 20 of the sensor body 12 by conventional methods. The sensor body includes an internal chamber 22 and a membrane or diaphragm 24 disposed along one end of the internal chamber, and the membrane or diaphragm 24 is configured to move in response to the application of fluid pressure to the membrane or diaphragm 24.

[0013] Fluid from an external source enters the pressure sensor 10 through an opening 26 of a constant diameter. The opening 26 passes through the support 16 and provides a continuous unobstructed fluid flow communication with the internal chamber 22 of the sensor body. When the pressure of the fluid entering the pressure sensor changes, the membrane or diaphragm 24 is moved. The top cover 18 includes a chamber 28 that provides a known reference volume, and due to the movement of the diaphragm or membrane caused by the change in fluid pressure, the reference volume changes, and these changes are monitored and measured for the purpose of determining the fluid volume pressure therefrom. Such a pressure sensor includes an electrical pressure sensing element, such as a piezoresistive element, that can be connected to the membrane or other part of the sensor for the purpose of providing an output signal in response to a change in the characteristics of the sensor in response to the fluid pressure.

[0014] Such a prior art MEMS pressure sensor shown in FIG. 1 includes a sensing diaphragm or membrane designed to operate within a defined range of fluid pressure conditions and yield conditions of the diaphragm or membrane. If the fluid pressure received by the pressure sensor goes outside the defined range of conditions, such as during a transient fluid high pressure event or spike, the diaphragm or membrane may tear or be damaged in other ways, thereby potentially rendering the pressure sensor inoperable. In such a prior art pressure sensor 10, the fluid entering the pressure sensor enters directly into the internal chamber 22 of the pressure sensor through the opening 26 of the support and contacts the diaphragm or membrane 24. The volume moving from the opening of the substrate to the internal chamber of the sensor body increases slightly, but such a change in volume is not sufficient to mitigate or offset the impact of the shock on the diaphragm from such a transient fluid high pressure spike. As briefly described above, in order to address such limitations of prior art pressure sensors, external snubber devices are used, and such snubber devices are interposed between the external fluid source and the MEMS pressure sensor.

[0015] Figure 2 shows an exemplary pressure sensor assembly 30 disclosed herein. In one example, the pressure sensor is a MEMS sensor comprising a sensor body 32 having an internal cavity 34, with a membrane 36 positioned at one end of the cavity, and the cavity having a conical shape that tapers outwardly as it moves outward from the membrane towards the cavity opening. A top cover or upper support 38 is disposed over the sensor body 32 and positioned to cover the membrane 36. A support 40 is connected to the lower surface 42 of the sensor body 32, and the support 40 includes an opening or cavity 44 that extends through the support 40, and the cavity 44 has a conical configuration that tapers outwardly as it moves away from the sensor body. The support opening is aligned with the cavity 34 of the sensor body to facilitate fluid transport between the support opening and the cavity 34 of the sensor body. A first substrate 46 is attached to the lower surface 48 of the support 40, and the first substrate 46 includes a volume expansion chamber 50 that extends from the first support to an inlet port 52 on the side opposite the support. The first substrate 46 includes sidewalls 54 attached to the support, and the sidewalls 54 extend along the outer periphery of the lower surface 48 of the support from the support, and the volume expansion chamber is defined within the substrate sidewalls. The inlet port 52 is disposed through a substrate base portion 54 that connects to the substrate sidewalls. A second substrate 56 is attached to the lower surface 58 of the first substrate 46, and the second substrate 56 includes a passage 60 that extends through the second substrate 56, and the passage 60 is aligned with the inlet port 52 of the first substrate. In one example, the inlet port 52 of the first substrate has a size with a reduced diameter compared to the passage 60 of the second substrate. The overall structure of the pressure sensor assembly of this example is configured to facilitate the flow of fluid through the second substrate and into the sensor body within the pressure sensor assembly. The mechanism of the inlet port 52 of the first substrate with a reduced diameter and the volume expansion chamber 50 of the first substrate operate together to reduce the spike action of the pressure fluid entering the sensor assembly and proceeding towards the membrane 36 of the sensor body.

[0016] In one example, the sensor body can be formed from silicon and can be provided, for example, as a silicon wafer in the form of single crystal silicon or other suitable forms of silicon. The support 40 can be formed from a material having a coefficient of thermal expansion similar to that of the material used to form the sensor body. In one example, the support can be selected from the group including silicon or other materials such as glass or PYREX that are chemically inert and can be joined to the sensor body. In one example, the support 40 is formed from glass. The top cover or upper support 38 of the pressure sensor is optional and can be formed from the same type of material as the support 40 described above and is attached or joined to the sensor body. The upper support 38 includes an internal chamber 62 configured to provide a reference volume. The openings in the support 40 can be formed by conventional methods such as machining, etching, molding, etc.

[0017] A feature of this exemplary pressure sensor assembly 30 is that the fluid pressure spike reduction mechanism is an integral part of the assembly formed by machining processes, etching processes, deposition processes, etc. The first substrate 46 and the second substrate 56 can be attached to the sensor body and can be supported by conventional techniques using suitable adhesive materials, glass frit, etc. The first substrate and the second substrate may be formed from the same material or different materials. In one example, the first substrate and / or the second substrate can be formed from a material having a coefficient of thermal expansion between that of the support and that of an external device to which the second substrate is attached to provide an external fluid, thereby providing a transition in the coefficient of thermal expansion between the support and such an external device and acting to reduce or eliminate a coefficient of thermal expansion mismatch that could cause damage to the sensor assembly during operation. In one example, the first substrate and / or the second substrate can be formed of the same material or different materials, which can include glass or ceramic materials. In one example, the second substrate is formed from a ceramic material such as aluminum oxide (Al2O3). Although a particular type of ceramic material has been disclosed, it should be understood that other types of ceramic materials that provide the desired coefficient of thermal expansion transition mechanism described above can also be used.

[0018] FIG. 3 shows an exemplary pressure sensor assembly 70 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, a top cover or support 38, and a support 40 similar to the support shown in FIG. 2 above. In this example, a substrate 72 is attached to the lower surface 74 of the support 40, and the substrate 72 is formed from several substrate members. In this example, a first substrate member 75 is attached to the support, and the first substrate member 75 includes a passage 76 that passes through the first substrate member 75, and the passage 76 is aligned with an opening 44 in the support and is in fluid flow communication with the opening 44. A substrate wall member 78 is attached along the outer periphery to the lower surface portion of the first substrate member 75, thereby defining an internal chamber 80 within such a substrate wall member 78. A substrate base member 82 is attached to the lower surface portion of the substrate wall member 78, and the substrate base member 82 includes an inlet opening 84 that extends through the substrate base member 82. On one side of the inlet opening 84, a substrate central member 96 is attached to the substrate base member 82 and positioned above the opening to deflect the fluid entering the substrate 72 through the inlet opening 84 into the first chamber cavity 88 positioned on one side of the substrate central member 96. As shown in FIG. 3, the fluid in the first chamber cavity 88 can pass through the horizontal passage 90 defined between the substrate central member 96 and the first substrate member 75 and enter the second chamber cavity 92. The substrate central member 96 is positioned to partially block the passage 76 through the first substrate member 75. Thus, in the case of a high-pressure spike state, in addition to the change in the fluid path direction provided by the combination of the positioning of the inlet opening 84 of the substrate base member with respect to the passage 76 of the first substrate and the arrangement position of the substrate central member 96 between the inlet opening 84 of the substrate base member and the passage 76 of the first substrate, the fluid entering the substrate can be reduced by the enlarged volume provided by one or both of the first chamber cavity and the second chamber cavity.

[0019] In this example, as described above, different substrate members forming the substrate 72 can be connected together, for example, by adhesive bonding, glass frit, etc. In one example, the substrate members are connected together by screen-printing glass on the substrate before assembly and then assembling the substrate members and subjecting the assembly to a high temperature useful for joining the substrate members together. In one example, all of the different substrate members can be formed from the same type of material as described above, or from materials having different thermal expansion characteristics for the purpose of providing a desired thermal expansion buffer and transition function between the support and the device providing the external fluid attached to the substrate.

[0020] Figure 4 shows an exemplary pressure sensor assembly 100 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, a top cover or support 38, and a support 40 similar to the support shown in FIG. 2 above. In this example, a substrate 102 is attached to the lower surface 104 of the support 40. Unlike the example shown in FIG. 3 above, the substrate 102 in this example is provided in the form of a laminated structure of a plurality of substrate layers. In one example, the substrate 102 can be provided in the form of a multilayer ceramic material such as LTCC or HTCC formed during a sintering process. Different layers can be configured to provide a desired pressure spike reduction mechanism. In this example, a first layer 106 is configured to adhere to the support 40, has an opening 108 therethrough, and the opening 108 is in fluid flow communication with the support opening 44. The first layer extends outwardly to provide an outer wall 110 that enables the formation of a volume expansion cavity or chamber 112 within the support. A second layer 114 is joined to the lower surface of the first layer 106 and is identically configured. A number of substrate sidewall layers 116 are configured to have the same outer dimensions as layers 106 and 114 and have a reduced wall thickness for the purpose of forming a chamber 112 that extends radially outwardly from the opening 108. A substrate base layer 118 is attached to the last of the substrate sidewall layers 116, and the substrate base layer 118 extends inwardly to define the chamber and form an inlet opening 120 of the substrate 102. The multilayer substrate structure thus configured operates to provide a pressure spike reduction mechanism through a volume expansion chamber 112 formed within the structure and positioned between the substrate inlet opening 120 and the substrate opening 108. In one example, the substrate inlet opening 120 and the substrate opening 108 are also axially offset from each other and operate to provide some reduction of fluid pressure spikes.

[0021] FIG. 5 shows an exemplary pressure sensor assembly 150 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, a top cover or support 38, and a support 40 similar to the support shown in FIG. 2 above. In this example, a substrate 152 is attached to the support 40. In this example, the substrate 152 includes a substrate top member 154 attached to the lower surface of the support, and the substrate top member 154 includes a passageway 156 therethrough, and the passageway 156 is sized similar to the support opening 44. A substrate wall member 158 is attached along the outer periphery to the substrate top member, and the substrate wall member 158 extends downwardly from the substrate top member, thereby providing a volume expansion cavity or chamber 160 defined within the wall member, and the chamber 160 is in fluid flow communication with the substrate passageway 156 and the support opening 44. A porous material 162 is disposed within the cavity 160, and the porous material 162 has various irregular or regular channels disposed therein that allow fluid flow from the base portion 164 through the substrate to the support 40, but there is no single defined flow path. In one example, the porous material can be a ceramic material, although other materials having similar features and characteristics can also be used. Alternatively, instead of using a single porous member to fill the substrate cavity, the cavity can be filled with a plurality of slices that together operate to form a porous composite that functions similarly to provide a plurality of irregular or regular fluid flow channels when combined. In this example, the porous member disposed within the substrate cavity operates to reduce fluid pressure spikes as the fluid passes through the substrate 152. Although the use of such a porous member or material has been described in this example, it should be understood that the use of such a porous member or material can also be used with other exemplary pressure sensor assemblies disclosed herein for the purpose of contributing to the desired effect of reducing fluid pressure spikes before reaching the sensor membrane.

[0022] FIG. 6 shows an exemplary pressure sensor assembly 200 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, and a top cover or support 38. In this example, a support 202 is attached to the sensor body after wafer-level processing, thereby enabling the use of a larger-sized support. In this example, the support is configured to include a top section 204 having an opening 206, the opening 206 being disposed to pass through the top section 204 and being aligned with a sensor body opening 208 and having a diameter similar to that of the sensor body opening 208. The top section of the support is attached to the lower surface of the sensor body. The support includes a wall section 212 that extends downward from the top section and defines a volume expansion cavity or chamber 214 within the support 202. The feature of forming the support after wafer-level formation of the sensor body enables the use of a larger-scale support that can operate to provide a pressure spike mitigation function. The wall section of the support is attached to a substrate 218 along a base portion 216. In this example, the substrate 218 has a fluid inlet opening 220 that is reduced in size compared to the chamber 214, and the fluid inlet opening 220 is positioned in alignment with the support opening 206, but can also be offset from the support opening if desired to contribute to the pressure spike mitigation function. The support can be attached to the sensor body, and the support can be attached to the substrate by an adhesive or other bonding material or technique known in the art as disclosed above. In one example, the substrate is formed from glass, and the substrate is formed from a ceramic material to provide the desired thermal expansion buffering action discussed above. In another example, a glass support can be joined to the sensor body by using anodic bonding, thereby providing a desired bond between the glass support and the sensor body without using an adhesive or the like. In such an example, the ceramic substrate should be attached by using the glass bonding described above.

[0023] FIG. 7 shows an exemplary pressure sensor assembly 300 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, and a top cover or support 38. In this example, a substrate 302 is attached to the lower surface of the sensor body, and the substrate 302 is sized to have an outer dimension that is considerably larger than the sensor body. In one example, the substrate has a thickness that extends downwardly away from the body and includes multi-directional passages 306 therein, and the passages 306 extend from an inlet opening 308 that extends from the bottom surface 310 of the substrate to an outlet opening 312 on the opposite side of the substrate that is in fluid flow communication with the sensor body opening. In one example, the substrate passage 306 includes five sections that extend between the inlet opening 308 and the outlet opening 312. A first section 316 of the passage extends from the inlet opening 308, is oriented horizontally within the substrate at approximately 90 degrees to the inlet opening 308, and extends to a second section 318 of the passage, and the second section 318 of the passage is oriented at approximately 90 degrees to the first section 316. A third section 320 of the passage extends from the second section 318 of the passage and is oriented at approximately 90 degrees to the second section 318 of the passage. A fourth section 322 of the passage extends from the third section 320 of the passage and is oriented at approximately 90 degrees to the third section 320 of the passage. A fifth section 324 of the passage extends from the fourth section 322 of the passage, is oriented at approximately 90 degrees to the fourth section 322 of the passage, and extends to the outlet opening 312, and the outlet opening 312 is oriented at approximately 90 degrees to the fifth section of the passage. With this configuration, the inlet opening 308, the outlet opening 312, the second section 318 of the passage, and the fourth section 322 of the passage are each oriented parallel to each other within the substrate, and the first section 316 of the passage, the third section 320 of the passage, and the fifth section 324 of the passage are each oriented parallel to each other within the substrate. Although specific examples have been described regarding how the passages within the substrate can be configured for the purpose of reducing pressure spikes, it should be understood that other configurations of passage sections that operate to provide a pressure spike reduction function are also within the scope of the present disclosure.

[0024] In this example, the substrate 302 is attached to an external device 330, which has a port 332 disposed within the external device 330 for delivering external fluid to the pressure sensor assembly for pressure measurement. In one example, the external device can be formed from a material having a coefficient of thermal expansion different from that of the substrate material and different from the coefficient of thermal expansion of the sensor body. Thus, it is desirable for the substrate to be formed from a material having a coefficient of thermal expansion that provides a transition in thermal expansion characteristics between those of the external device and those of the sensor body. In one example, the substrate can be formed from glass. In such a case, similar to the example shown in FIG. 7, the substrate can be joined to the sensor body by anodic bonding. When the substrate is formed from a ceramic material, the substrate can be attached to the sensor body by the bonding techniques discussed above. In one example, the substrate 302 can provide a surface that can be used for electrical connection to the electrical sensing element of the sensor body and / or for placement of the pressure sensor electrical interface unit 340, and the electrical interface unit 340 is disposed on the surface by adhesion or other attachment means, along with desired wire connections 342 useful for electrical connection between the sensor body and / or other elements such as a printed circuit board.

[0025] FIG. 8 is a perspective view of the pressure sensor assembly 400 shown in FIG. 7, comprising a sensor body 32 and a top cover or support 38 disposed on the sensor body 32, and the sensor body is attached to the substrate 302. In this example, the substrate is shown as a laminated structure formed from several different layers 402. Such a laminated structure is useful for the purpose of forming a passage within the substrate that includes a plurality of sections, and those sections can be formed by etching each layer as needed to provide the desired passage configuration. After forming the desired passage sections, the plurality of layers are combined and joined together to provide the substrate.

[0026] FIG. 9 shows an exemplary pressure sensor assembly 450 disclosed herein having a sensor body 32 with an internal cavity 34 and a membrane 36, and a top cover or support 38. In this example, a substrate 452 is attached to the lower surface of the sensor body, and the substrate 452 is sized to have dimensions somewhat similar to the sensor body. The substrate includes a passage 454 extending through the substrate, and the diameter of the passage 454 is considerably smaller than the opening 456 of the sensor body. In this example, the substrate is disposed within or attached to a printed circuit board 458. In this embodiment, the substrate is embedded within the printed circuit board, and the printed circuit board extends radially around the wall portion 460 of the substrate. The substrate is attached to an external device 462, and the external device 462 has a port 464 disposed within the external device 462 for delivering external fluid to the pressure sensor assembly for pressure measurement. In this example, the external device port is sized to have a diameter larger than the diameter of the substrate passage, and both the substrate and a portion of the printed circuit board are attached to the external device. In this example, the printed circuit board 458 provides a surface that can be used for electrical connection to the electrical sensing element of the sensor body and / or for the placement of a pressure sensor electrical interface unit 466, and the pressure sensor electrical interface unit 466 is disposed on the surface by adhesion or other attachment means, along with desired wire connections 468 useful for electrical connection between the sensor body and the printed circuit board.

Claims

1. A sensor body (32) comprising a sensing membrane (36) and an open cavity (34), wherein the open cavity (34) is located adjacent to the sensing membrane (36) within the body, and is arranged within the body to bring fluid from an external source into contact with the membrane for measuring the pressure of the fluid, the sensor body (32); A support (40) connected to the body, comprising a channel (44) extending through the support (40) for receiving the fluid, the channel being in fluid flow communication with the membrane (36), the support (40); A substrate (46) connected to the support (40), comprising a channel (52) extending through the substrate (46) for receiving the fluid from an external source, the fluid being transmitted through the substrate (46) to the support (40), the substrate (46); One of the channels (52) of the substrate (46) or the support channel (44) comprises a pressure relief mechanism disposed therein for reducing the transmission of pressure spikes of the fluid from the external source to the sensing membrane; The pressure relief mechanism comprises a porous member (162) disposed in one of the support channel (44) and the substrate channel (52); A pressure sensor assembly (30).

2. A sensor body (32) comprising a sensing membrane (36), wherein the sensing membrane (36) is arranged within the body to bring fluid from an external source into communication with the membrane for measuring the pressure of the fluid, the sensor body (32); A support (40) connected to the body, comprising a channel (44) extending through the support (40) for receiving the fluid, the channel being in fluid flow communication with the membrane (36), the support (40); A substrate (46) connected to the support (40), comprising a channel (52) extending through the substrate (46) for receiving the fluid from an external source, the fluid being transmitted through the substrate (46) to the support (40), the substrate (46); One of the channels (52) of the substrate (46) or the support channel (44) is provided with a pressure relief mechanism disposed therein to reduce the transmission of the pressure spike of the fluid from the external source to the sensing film. The substrate (46) is a pressure sensor assembly (30) formed of a material having a coefficient of thermal expansion between the coefficient of thermal expansion of the support (40) and the coefficient of thermal expansion of the external fluid source. **Claim 3** The pressure sensor assembly (30) according to claim 1, wherein the sensor body (32) is formed of silicon and the substrate is formed of a ceramic material. **Claim 4** A sensor body (32) comprising a sensing film (36), wherein the sensing film (36) communicates the fluid from an external source and is disposed within the body to measure the pressure of the fluid, the sensor body (32); A support (40) connected to the body, the support (40) having a channel (44) extending therethrough for receiving the fluid, the channel being in fluid flow communication with the film (36), the support (40); A substrate (46) connected to the support (40), the substrate (46) having a channel (52) extending therethrough for receiving the fluid from an external source, the fluid being transmitted through the substrate (46) to the support (40), the substrate (46); One of the channels (52) of the substrate (46) or the support channel (44) is provided with a pressure relief mechanism disposed therein to reduce the transmission of the pressure spike of the fluid from the external source to the sensing film. The pressure sensor assembly (30) comprising several ceramic elements (75), (78), (96), and (82) joined together to form the pressure relief mechanism. **Claim 5** The pressure relief mechanism of the pressure sensor assembly (30) according to claim 1 comprises a volume expansion portion of one of the substrate channel (52) or the support channel (44). **Claim 6** The pressure reducing mechanism is the pressure sensor assembly (30) according to claim 1, including two or more directional changes in one of the support channels (44) and the substrate channels (52) when moving through the respective support (40) or the substrate (46).

7. A sensor body (32) comprising a sensing membrane (36) and an open cavity (34), wherein the open cavity (34) is located adjacent to the membrane (36) within the body, and a sensor body (32) that enables fluid from an external source to contact the membrane to measure the pressure of the fluid. A substrate (46) connected to the body (32), the substrate (46) comprising a channel (52) extending through the substrate (46) for receiving fluid from an external source and transmitting the fluid through the substrate to the body. A fluid pressure reducing mechanism disposed within the pressure sensor assembly to reduce the transmission of pressure spikes of fluid entering the pressure sensor assembly upstream of the membrane (36). Comprising The pressure reducing mechanism is a pressure sensor assembly (30) comprising a porous member (162) disposed in the substrate channel (52).

8. The fluid pressure reducing mechanism is disposed within the substrate (46) and is selected from one or more of a volume expansion portion of the channel (52), two or more directional changes within the channel (52), a porous member (162) disposed within the channel (52), and a movable element within the channel, the pressure sensor assembly (30) according to claim 7.

9. The sensor body (32) is formed from silicon, and the substrate (46) is formed from a material having a coefficient of thermal expansion between the coefficient of thermal expansion of the sensor body (32) and the coefficient of thermal expansion of an external fluid pressure source, the pressure sensor assembly (30) according to claim 7.

10. Further comprising a support (40) interposed between the sensor body (32) and the substrate (46), the support (40) includes a channel (44) extending through the support (40), and the channel (44) communicates with the support channel (52) and the main body open cavity (34). The pressure sensor assembly (30) according to claim 7.

11. A method for reducing a pressure spike of an external fluid measured by a pressure sensor assembly (30), Inducing a fluid into a substrate (46) having a channel (52) extending through the substrate (46); Transmitting the fluid from the substrate (46) to a sensor body (32) connected to the substrate (46), the sensor body (32) comprising an open cavity (34) and a membrane (36), the membrane (36) being located at an end of the open cavity (34), and the membrane (36) being configured to measure the pressure of a fluid contacting the membrane (36) through the open cavity (34). A step of transmitting; By guiding the fluid entering the pressure sensor assembly (30) through a pressure reducing mechanism comprising a porous member (162) disposed within the pressure sensor assembly (30) and positioned upstream of the membrane (36) and disposed in the channel (52). A method comprising reducing the pressure spike of the fluid.

12. The reducing step includes guiding the fluid through a channel of the assembly (30) including two or more direction changes, guiding the fluid into a volume expansion portion located upstream of the sensor body (32) within the assembly, and guiding the fluid into contact with a movable element disposed in a channel of the assembly, and guiding the fluid into contact with a porous element (162) disposed in a channel of the assembly. The method according to claim 11, comprising one or more of the above.

13. A method for reducing a pressure spike of an external fluid measured by a pressure sensor assembly (30), Inducing fluid into a substrate (46) having a channel (52) extending through the substrate (46); The pressure sensor assembly (30) includes a support (40) interposed between the substrate (46) and the sensor body (32), the support (40) including a channel (44) extending through the support (40), and transmitting the fluid from the substrate (46) through the support channel (44) to the sensor body (32), the sensor body (32) including an open cavity (34) and a membrane (36), the membrane (36) being located at an end of the open cavity (34), the membrane (36) being configured to measure the pressure of the fluid passing through the open cavity (34) and contacting the membrane (36); Reducing a pressure spike of the fluid by inducing the fluid entering the pressure sensor assembly (30) to pass through a porous member (162) disposed in one of the support channel (44) and the substrate channel (52) and positioned upstream of the membrane (36) within the pressure sensor assembly (30). Claim 14. Some of the ceramic elements are A wall member joined along an outer periphery of the substrate (46); A base member facing the substrate (46), joined to the wall member, and having a base channel extending through the base member for receiving the fluid from an external source; A central member joined to the base member, covering the base channel, and partially covering the substrate channel (52); A chamber surrounded by the substrate, the wall member, and the base member; The pressure sensor assembly (30) according to claim 4. A sensor body (32) including a sensing membrane (36) and an open cavity (34), the open cavity (34) being located adjacent to the membrane (36) within the body and enabling measurement of the pressure of a fluid by contacting the fluid from an external source with the membrane; A substrate (46) connected to the main body (32), the substrate (46) having a channel (52) extending through the substrate (46) for receiving fluid from an external source and transmitting the fluid through the substrate to the main body. A fluid pressure reducing mechanism disposed within the pressure sensor assembly to reduce the transmission of pressure spikes of fluid entering the pressure sensor assembly upstream of the membrane (36). Comprising The sensor main body (32) is formed of silicon, and the substrate (46) is formed of a material having a coefficient of thermal expansion between the coefficient of thermal expansion of the sensor main body (32) and the coefficient of thermal expansion of an external fluid pressure source. Pressure sensor assembly (30).

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