Title of Invention

PRESSURE SENSOR MODULE

Abstract

The invention relates to a pressure sensor module for measuring a differential pressure, consisting of at least a sensor chip for measuring a differential pressure, and a module housing which has at least two supply lines which are separated from one another by the sensor chip and in which different pressures are at least occasionally present, a valve (15) is arranged in at least one supply line (10, 12), which valve closes this supply line (10, 12) when the sensor chip (3) no longer separates the supply lines (10, 12) from one another, characterized in that said valve (15) has a movable member that is formed as a float (22). Figure 1.

Full Text

The invention starts out from a pressure sensor module for measuring a differential pressure, consisting of at least a sensor chip for measuring a differential pressure, and a module housing which has at least two supply lines which are separated from one another by the sensor chip and in which different pressures are at least occasionally present, a valve is arranged in at least one supply line, which valve closes this supply line when the sensor chip no longer separates the supply lines from one another. In modern engine control systems, the fuel pressure is regulated so as to reduce heating-up of the fuel and to avoid emission from fuels. In this connection, the difference between the fuel pressure and the suction pipe pressure is measured by means of a fuel pressure sensor. Cost-effective silicon-based micromechanical sensors are currently used as fuel pressure sensors. In these, a membrane side facing away from a circuit is acted on by fuel, and a membrane side facing the circuit is connected to the suction pipe. If the membrane of the sensor breaks as a result of manufacturing defects or handling errors, the fuel is pumped through the ruptured membrane directly into the suction pipe and can lead to destruction of the engine by fuel impact. Differential pressure sensors are known, which, on a pressure side, additionally have a metal membrane on which the pressure is exerted and which transmits this pressure to the membrane of the sensor via a silicone oil. If the membrane of the sensor breaks owing to overloading, the metal membrane comes up against a support surface provided therefor and takes up the pressure, so that the medium on the pressure side cannot enter the sensor housing and/or the area of the other pressure side. Only a small quantity of the silicone oil present enters the suction pipe. However, owing to the complicated construction for the metal membrane and the design of the hermetically sealed volume for the silicone oil, these sensors are relatively expensive. This is due to the material costs and process costs for the connection technology, the filling with oil and adjustment after filling with oil. In order to comply with precision requirements, a minimum size of the metal membrane, and thus a corresponding construction size as well, is required, which precludes miniaturization. From GB 2264070 Al, a device with a differential pressure sensor and a valve is known, which valve can close a supply line to the differential pressure sensor. This can take place only via an electronic control. Pressure sensor which prevents leakage of fuel is disclosed in US 5,621,176. Advantages of the invention In contrast, the pressure sensor module according to the invention has the advantage that transfer of a medium from one supply line to another supply line is prevented in a simple manner, this taking place irrespective of the pressure, or that is to say irrespective of the flow of the medium. Advantageous developments and improvements of the pressure sensor module is that the valve has a movable member that is formed as a float. An advantageous configuration of a valve is achieved by a float being arranged between two narrowings of a supply line and closing the latter by resting against one narrowing when a sensor chip no longer separates the supply lines from one another. A narrowing can be formed advantageously by a grating. A sphere, which has a smaller cross section than the supply line, is advantageously used as a float. An advantageous embodiment of the invention in which the pressure sensor module is connected to a suction pipe of an internal combustion engine and to a fuel line. It is advantageous if the pressure sensor module is installed vertically, because in this way the float does not close the supply line in an undesired manner. It is advantageous if the float has a lower density than the fuel, because the float, owing to the buoyancy force in the fuel, is brought up against the second narrowing and in this way closes the line, so that no fuel can enter the suction pipe. 3 It is advantageous if the narrowing or the float additionally has sealing elements, which facilitate sealing. For guiding the float, the supply line advantageously has guide rails, which ensure that the float always comes to rest against the narrowing optimally and that sufficient space is available in normal operation for medium exchange when changes in suction pipe pressure take place. Drawing Illustrative embodiments of the invention are shown in a simplified manner in the accompanying drawings and are explained in greater detail in the description below. Figure 1 shows a pressure sensor module according to the invention; Figures 2a and b show details of further pressure sensor modules according to the invention; Figure 2c shows a section along the line A-A in Figure 2b; Figure 2d shows a further illustrative embodiment for a float, and installed in a pressure sensor module according to the invention. Description of illustrative embodiments Figure 1 shows a pressure sensor module 1 according to the invention, which consists of inter alia a module housing 8, in which a sensor cell 5 is at least in part arranged. The sensor cell 5 contains, for example, a sensor chip 3 (Fig. 3) which can measure a pressure or a pressure difference. This is usually a silicon-based micromechanical sensor which has a membrane. A first supply line 10, which is, for example, connected to a suction pipe of an internal combustion engine, and a second supply line 12, which is, for example, connected to a fuel line, are connected to the sensor cell 5. The sensor chip 3 with its membrane separates the first supply line 10 and the second supply line 12 from one another, so that no medium from one supply line 10, 12 enters the other supply line 12, 10. Arranged in, for example, the first supply line 10, in a part region 10b, is a valve 15 which closes the first supply line 10 if the membrane breaks and in this way separates the first supply line 10 and the second supply line 12 from one another, so that the medium from the second supply line 12 cannot enter the first supply line 10. The valve 15 is, for example, a part region 10b of the first supply line 10, which line has a first narrowing 18 and a second narrowing 19. The remaining part of the supply line 10 is designated by ,10a. Arranged between the two narrowings 18, 19 is a float 22 which forms the moving valve element of the valve 15. When the membrane separates the first supply line 10 and the second supply line 12 from one another, the float 22 lies, on account of its weight, against or on the second narrowing 18 and does not close the first supply line 10. In other words, a pressure in the first 5 supply line 10 acts on one membrane side, and a pressure from the second supply line 12 acts on the other membrane side, so that a differential pressure is measured. The first narrowing 18 is, for example, a grating. The second narrowing 19 is formed by, for example, a reduction in a cross section of the first supply line 10b. The float 22 is, for example, a sphere, a cylinder or another shape, which can close the supply line 10 by resting against the second narrowing 19 forming a valve seat, and which has a smaller cross section than the, for example, round supply line 10b between the two narrowings 18, 19. When the membrane no longer separates the first supply line 10 and the second supply line 12 from one another, the, for example, higher pressure in the second supply line 12 causes the float 22 to be pressed against the second narrowing 19 by the higher pressure in the second supply line 12 and the flowing medium and in this way to close the first supply line 10, so that the first supply line 10 and the second supply line 12 are again separated from one another. If the medium in the second supply line 12 is a liquid medium such as, for example, a liquid fuel and, when the membrane has ruptured, this enters the supply line 10b through the first narrowing 18, the float is subjected to a buoyancy force, as the float 22 advantageously has a lower density than the liquid fuel. The float 22 is pressed against the second narrowing 19 by the buoyancy force and by the higher pressure in the supply line 12. The valve 15 is therefore controlled without additional aids, as the medium in one supply line 12, or that is to say the pressure difference in the supply lines 10, 12, brings about closing of the valve 15. The pressure sensor module 1 also has electrical connection elements 25, which are part of a connector 27 which serves for electrical connection to an external electrical energy source and/or control unit . At least one supply line 10, 12, for example, has on its external circumference a sealing ring 29, for example, which serves for sealing when the pressure sensor module 1 is inserted into another component. The pressure sensor module 1 also has a fastening flange 31 which serves for fastening the pressure sensor module 1 to the component. Figure 2a shows a detail from Figure 1 for a further illustrative embodiment of the invention. It is essentially a further embodiment of the valve 15 which is shown. The first narrowing 18 is formed by, for example, an opening in the housing 37 (Fig. 3) of the sensor cell 5, which has a smaller cross section than the float 22. The second narrowing 19 is, as in Figure 1, formed by a reduction in the cross section of the first supply line 10b. The float 22 is formed by an element 33 which has continuous longitudinal grooves 35. The longitudinal grooves 35 ensure that a connection exists from the first supply line 10 to the sensor cell 5 even if a surrounding lateral surface of the element 33 is identical with the cross section of the first supply line 10b between the two narrowings 18, 19. For example, the supply line 10b has a round cross section in this region, and the float 22 is formed by a cylinder which has the corresponding continuous longitudinal grooves 35. In places, the cylinder 33 rests directly against the supply line 10b, a passage from the first supply line 10 to the sensor cell 5 nevertheless being ensured by the longitudinal grooves 35. The cylinder 33 too closes the supply line 10, as already explained in the case of Figure 1, if the membrane has ruptured and that end face of the cylinder 33 facing the narrowing 19 is adapted to the narrowing 19, the end face and the narrowing 19 being, for example, of conical design. Figure 2b shows a sphere as the float 22, which sphere is guided by guide rails 17. A cylinder or another shape can also be guided by the guide rails. The guide rails 17 ensure that, the sphere always comes to rest against the narrowing 19 optimally, because the diameter of a circle, which is formed by the free end of the guide rails 17, corresponds approximately to the outside diameter of the sphere. In order to facilitate the sealing between the narrowing 19 and the float 22, at least one sealing element 16, for example a rubber bead running all the way round, is arranged in the region of the narrowing 19. The sealing elements 16 are elastically deformable, so that a large sealing surface is achieved. The sealing element 16 can also be present on the float 22. Figure 2d shows a sphere as the float 22, which sphere is surrounded by a sealing element 16. Figure 2c shows a section along the line A-A in Figure 2b. The space between the guide rails 17, which have the shape of, for example, a triangle or a small rod in cross section, forms that part of the supply line 10 through which the pressure from the supply line 10 can act on the membrane of the sensor chip 3. Figure 3 shows a sensor cell 5 as is used, for example, in the pressure sensor module 1 according to the invention. The sensor cell 5 has a sensor housing 37, in which the sensor chip 3 is arranged on a glass base 39. Inside the sensor housing 37, the sensor chip 3 is protected, for example by a gel 45. The sensor chip 3 is connected by bonding wires 41 to electrical sensor connection elements 43, which are in turn connected to the electrical connection elements 25. The housing 37 has an opening, which is arranged in the region of or even forms the first narrowing 18 (Fig. 2) and is connected to the supply line 10. The other si.de of the sensor chip 3 is connected to the supply line 12, as is indicated by broken lines. WE CLAIM 1. Pressure sensor module for measuring a differential pressure, consisting of at least a sensor chip for measuring a differential pressure, and a module housing which has at least two supply lines which are separated from one another by the sensor chip and in which different pressures are at least occasionally present, a valve (15) is arranged in at least one supply line (10, 12), which valve closes this supply line (10, 12) when the sensor chip (3) no longer separates the supply lines (10, 12) from one another, characterized in that said valve (15) has a movable member that is formed as a float (22). 2. Pressure sensor module as claimed in claim 1, wherein the valve (15) is formed by at least two narrowings (18, 19) of one supply line (10, 12), and a float (22) which is arranged movably in this supply line (10, 12), is arranged between the two narrowings (18, 19), lies on a first narrowing (18), on account of its cross section does not close the supply line (10), and closes the supply line (10) by resting against the second narrowing (19) when the sensor chip (3) no longer separates the supply lines (10, 12) from one another. 3. Pressure sensor module as claimed in claim 2, wherein the first narrowing (18) is formed by a grating. 4. Pressure sensor module as claimed in claim 2, wherein the float (22) is a sphere which has a smaller cross section than the supply line (10, 12). 5. Pressure sensor module as claimed in claim 2 or 4, wherein the float (22) is formed by an element (33) with longitudinal grooves (35). 9 6. Pressure sensor module as claimed in claim 1, wherein the pressure sensor module (1) has a first supply line (10) and a second supply line (12), in that the first supply line (10) is connected to a suction pipe of an internal combustion engine, in that the second supply line (12) is connected to a fuel line, and in that the valve (15) is arranged in the first supply line (10). 7. Pressure sensor module as claimed in claim 2, wherein a longitudinal axis of the at least one part of the supply line (10, 12) in which the float (22) is arranged runs approximately vertically. 8. Pressure sensor module as claimed in any one of claims 2, 4, 5 or 7, wherein the float (22) has a lower density than the liquid fuel. 9. Pressure sensor module as claimed in any one of claims 1, 2 or 6, wherein two supply lines (10, 12) are provided, and in that a pressure prevails at least occasionally in one supply line (10, 12), which pressure is greater than or equal to the pressure in the other supply line (12, 10). 10. Pressure sensor module as claimed in claim 2 or 6, wherein the supply line (10, 12) has guide rails (17) at least in places between two narrowings (18, 19). 11. Pressure sensor module as claimed in any one of claims 2, 4, 5, 7 or 8, wherein the float (22) has at least one sealing element (16). 12. Pressure sensor module as claimed in claim 2, wherein at least one sealing element (16) is present in the region of the narrowing (18, 19) against which the float seals the supply line (10, 12).

Documents:

in-pct-2002-1053-che abstract.jpg

in-pct-2002-1053-che abstract.pdf

in-pct-2002-1053-che abstrcat-duplicate.pdf

in-pct-2002-1053-che claims-duplicate.pdf

in-pct-2002-1053-che claims.pdf

in-pct-2002-1053-che correspondence-others.pdf

in-pct-2002-1053-che correspondence-po.pdf

in-pct-2002-1053-che description (complete)-duplicate.pdf

in-pct-2002-1053-che description(complete).pdf

in-pct-2002-1053-che drawings-duplicate.pdf

in-pct-2002-1053-che drawings.pdf

in-pct-2002-1053-che form-1.pdf

in-pct-2002-1053-che form-18.pdf

in-pct-2002-1053-che form-26.pdf

in-pct-2002-1053-che form-3.pdf

in-pct-2002-1053-che pct.pdf

in-pct-2002-1053-che petition.pdf