Pressure sensor and method for manufacturing pressure sensor

Abstract

To provide a pressure sensor 1 having a housing 20, a plunger unit 11, and a measurement element 12.SOLUTION: A housing 20 has a housing inner section 20.3. A plunger unit 11 and a measurement element 12 are disposed in the housing inner section 20.3. The plunger unit 11 has a distal plunger end 11.1 and a proximal plunger end 11.2. The distal plunger end 11.1 is disposed further separately from the measurement element 12 as compared with the proximal plunger end 11.2 on a vertical axis A of a pressure sensor 1 and the distal plunger end 11.1 projects from the housing 20. The proximal plunger end 11.2 operably connected to the measurement element 12, and transmits pressure P of a medium M spreading out to the outside of the housing 20 to the measurement element 12. The pressure sensor 1 has a sleeve 30. The sleeve 30 is fastened to the housing 20. The sleeve 30 and the distal plunger end 11.1 are separated from each other by a gap 30.4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pressure sensor as described in the preamble of claim 1 and a method for manufacturing a pressure sensor as described in the preamble of claim 11.

Background Art

[0002] Pressure sensors are used in a wide variety of technical applications. International Publication No. 2006 / 032152 (A1) discloses a pressure sensor for measuring the pressure prevailing in an injection molding tool or in the pressure chamber of an internal combustion engine. The pressure sensor comprises a housing, a plunger and a measuring element. The housing has an interior, in which the plunger and the measuring element are arranged. With respect to the measuring element, the plunger has a distal plunger end and a proximal plunger end. The proximal end of the plunger is operatively connected to the measuring element. The pressure sensor can be fastened via the housing in a hole in the wall of the pressure chamber. When the pressure sensor is fixed in the hole, the distal end of the plunger projects from the housing into the pressure chamber. The pressure to be measured is transmitted from the distal end of the plunger to the proximal end of the plunger and acts on the measuring element.

[0003] The medium present in the pressure chamber is a liquid melt such as plastic or metal in an injection molding die or a mixture of fuel and air in an internal combustion engine. The medium exhibits temperatures of several hundred °C and pressures of several tens of MPa (several hundred bar). Due to the high sensitivity of the pressure sensor when measuring pressure, the plunger is arranged movably relative to the housing, which is achieved by a gap between the housing and the plunger. In addition, in order to prevent the medium from entering the interior of the housing through the gap and damaging or destroying the measuring element there, International Publication No. 2006 / 032152 (A1) teaches to arrange a metal annular diaphragm in the gap, the annular diaphragm being attached to the plunger and attached to the housing by a weld joint to seal the gap.

[0004] However, the welded joint of the annular diaphragm represents a force shunt, and a part of the pressure to be measured passes from the plunger through the force shunt into the housing, thus reducing the sensitivity of the pressure sensor when measuring the pressure. In particular, under high pressures exceeding 100 MPa (1000 bar), the annular diaphragm is arranged in a thick configuration to ensure long life, and then forms a significant force shunt. The annular diaphragm is welded to the housing and the plunger, also forming a vibrating system, which is excited and vibrates during pressure measurement, and this vibration may distort the pressure measurement. Finally, the location of the welded joint of the annular diaphragm within the gap between the housing and the plunger is difficult to reach with welding tools, which makes the production of the welded joint difficult and expensive.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] A first object of the present invention is to provide a pressure sensor that measures the pressure to be measured with high sensitivity and high precision. In particular, the pressure sensor should also be able to measure high pressures exceeding 100 MPa (1000 bar) with high sensitivity and high precision. As another object, a simple and cost-effective manufacturing method of the pressure sensor should be demonstrated.

Means for Solving the Problems

[0007] At least one of the objects is solved by the features of claim 1 or claim 11.

[0008] The present invention relates to a pressure sensor having a housing, a plunger unit, and a measuring element, wherein the housing has an interior of the housing, the plunger unit and the measuring element are arranged within the interior of the housing, the plunger unit has a distal plunger end and a proximal plunger end, the distal plunger end is arranged on the longitudinal axis of the pressure sensor further away from the measuring element than the proximal plunger end, the distal plunger end protrudes from the housing, the proximal plunger end is operatively connected to the measuring element and transmits the pressure of a medium extending outside the housing to the measuring element. The pressure sensor comprises a sleeve, the sleeve is attached to the housing, the sleeve and the distal plunger end are spaced apart from each other by a gap, and the pressure sensor comprises at least one sealing element, the sealing element sealing the gap against the medium up to the interior of the housing using a sealing pressure.

[0009] The present invention also relates to a method for manufacturing a pressure sensor comprising a housing, a plunger unit, and a measuring element, wherein the housing has an interior of the housing, the plunger unit and the measuring element are arranged within the interior of the housing, the plunger unit has a distal plunger end and a proximal plunger end, the distal plunger end is arranged on the longitudinal axis of the pressure sensor further away from the measuring element than the proximal plunger end, the distal plunger end protrudes from the housing, the proximal plunger end is operatively connected to the measuring element and transmits the pressure of a medium extending outside the housing to the measuring element. In a first step of the method, a housing and a sensor unit having a plunger unit and a measuring element are provided, the housing is pushed over the plunger unit along the longitudinal axis and placed on the sensor unit. In a second step of the method, at least one sealing element is provided, the sealing element is pushed over the distal plunger end along the longitudinal axis and placed on the housing. In a third step of the method, a sleeve is provided, the sleeve is pushed over the distal plunger end along the longitudinal axis and placed on the sealing element and the housing, the sleeve and the distal plunger end are spaced apart from each other by a gap, and the sealing element seals the gap against the medium up to the interior of the housing with a sealing pressure.

[0010] In contrast to the teaching of International Publication No. WO 2006 / 032152 (A1), the present invention avoids a force shunt for sealing the gap between the plunger and the housing. The gap is sealed by a sealing pressure, whereby the pressure to be measured is transmitted almost completely from the plunger to the measuring element, and high sensitivity and high precision are achieved when measuring the pressure.

[0011] Advantageous developments of the object of the invention are claimed in the dependent claims.

[0012] In an advantageous development, the sealing element is toroidal in shape and consists of an elastically sealing material such as an elastomer, in particular a fluoroelastomer or perfluoroelastomer, or rubber, in particular acrylonitrile-butadiene rubber.

[0013] In further contrast to the teaching of International Publication No. WO 2006 / 032152 (A1), the sealing element made of an elastic material does not represent a vibrating system that can be excited to vibrate during pressure measurement, and such vibrations can falsify the pressure measurement. By avoiding such vibrations, the pressure can be measured with high sensitivity and high precision.

[0014] In another advantageous development, in the third step of the method, a groove is formed radially on the inside of the sleeve and on the housing with respect to the longitudinal axis by placing a sleeve on the housing around the sealing element.

[0015] Such production of the groove for receiving the sealing element is simple and inexpensive.

[0016] In another advantageous development, the groove has a plurality of groove walls, the groove walls pre-compress the sealing element arranged in the groove, the pressure in the gap acts on the sealing element as a compression in addition to the pre-compression, and the pre-compression and the compression form the sealing pressure.

[0017] The two-stage sealing by pre-compression and compression ensures that even under low pressure, the medium cannot enter the interior of the housing through the gap and damage or destroy the measuring element at this location. The production of the grooves for applying pre-pressure to the sealing element is simple and inexpensive.

[0018] In another advantageous development, the groove has a rectangular or triangular or trapezoidal or round or semi-circular cross-section.

[0019] These various cross-sectional geometries enable adjustment of the magnitude of the pre-compression exerted by the groove walls on the toroidal sealing element. For a sealing element with given dimensions, a higher pre-compression is achieved with groove walls that are inclined with respect to the longitudinal axis or with round groove walls that are curved into the sleeve or the housing with respect to the longitudinal axis, compared to groove walls that are straight with respect to the longitudinal axis. This means that the pressure sensor can operate at high pressures exceeding 100 MPa (1000 bar) without the medium entering the interior of the housing through the gap. Manufacturing the various geometries of the grooves is simple and inexpensive.

[0020] In another advantageous development, the plunger unit comprises a pre-pressure sleeve and a pre-pressure body. The proximal plunger end merges into the pre-pressure sleeve, the pre-pressure sleeve surrounds a pre-pressure sleeve chamber, a measuring element is arranged in the pre-pressure sleeve chamber, the end of the pre-pressure sleeve facing away from the proximal plunger end is fastened to the pre-pressure body via a connection between the pre-pressure sleeve with material locking and the pre-pressure body, and the measuring element is arranged on the longitudinal axis between the proximal plunger end and the pre-pressure body under mechanical pre-pressure.

[0021] This development prevents mechanical stresses resulting from mounting the pressure sensor in the wall of the pressure chamber from reaching the measuring element from the housing and distorting the pressure measurement. Preventing the transmission of such mechanical stresses increases the sensitivity and accuracy of the pressure measurement.

[0022] Hereinafter, the present invention will be described in more detail by way of examples with reference to several embodiments with reference to the figures.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

[0024] In the above figures, the same reference numerals indicate the same objects.

[0025] FIGS. 1 to 6 show cross-sectional views of some embodiments of a part of the pressure sensor 1 according to the present invention. The pressure sensor 1 has a function of measuring the pressure P of the medium M in the pressure chamber C. The pressure chamber C can be arranged in an injection molding die, an internal combustion engine, or the like. In the injection molding die, the medium M is a liquid melt such as plastic or metal. In the internal combustion engine, the medium M is a mixture of fuel and air. The medium M can have a temperature T of several hundred degrees Celsius and a pressure P of several hundred MPa (several thousand bar). Preferably, the temperature T is in the range of 100° C. to 500° C., and the pressure P is in the range of 5 MPa (50 bar) to 500 MPa (5000 bar). The pressure P to be measured is schematically shown as a black arrow in FIGS. 1 to 6.

[0026] The pressure sensor 1 includes a sensor unit 10. The sensor unit 10 has a function of accommodating the measuring element 12. Although only a part of the sensor unit 10 is shown in FIGS. 1 to 6, the sensor unit 10 is shown in its entirety in the cross-sectional view of FIG. 7 and the exploded view of FIG. 8.

[0027] The pressure sensor 1 indicates a longitudinal axis A. FIGS. 1 to 8 show the pressure sensor 1 along the longitudinal axis A.

[0028] The pressure sensor 1 includes a housing 20. The housing 20 has a function of fastening the sensor unit 10 in the hole H in the wall W of the pressure chamber C. Fastening the pressure sensor 1 through the housing 20 in the hole H can be a screw connection. The screw connection is not shown in the figure.

[0029] In the embodiment shown in the figure, the housing 20 is a hollow cylinder and is made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. As can be clearly seen in FIG. 8, the housing 20 has a distal housing end 20.1 and a proximal housing end 20.2, and the distal housing end 20.1 is arranged on the longitudinal axis A, further away from the measurement element 12 than the proximal housing end 20.2. The housing 20 has a housing interior 20.3. With respect to the longitudinal axis A, the housing 20 radially surrounds the housing interior 20.3. The sensor unit 10 is arranged within the housing interior 20.3.

[0030] In addition to the measurement element 12, the sensor unit 10 comprises a plunger unit 11.

[0031] The plunger unit 11 has a first function of receiving the pressure P to be measured and transmitting this pressure to the measurement element 12. For this purpose, the plunger unit 11 has a distal plunger end 11.1, a proximal plunger end 11.2 and a preloading sleeve 11.3. The plunger unit 11 is made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. In the embodiment shown in the figure, the distal plunger end 11.1, the proximal plunger end 11.2 and the preloading sleeve 11.3 are integrally formed. The distal plunger end 11.1 and the proximal plunger end 11.2 are cylindrical and merge with each other. The proximal plunger end 11.2 merges with the preloading sleeve 11.3. The preloading sleeve 11.3 is a hollow cylinder and surrounds a preloading sleeve chamber 11.4. The measurement element 12 is arranged within the preloading sleeve chamber 11.4. The distal plunger end 11.1 is arranged on the longitudinal axis A, further away from the measurement element 12 than the proximal plunger end 11.2. The distal plunger end 11.1 has an end face at its end, which is also called a pressure absorption face 11.11. The pressure P to be measured acts on the distal plunger end 11.1 via the pressure absorption face 11.11 and is transmitted from the distal plunger end 11.1 to the proximal plunger end 11.2. Then, the pressure P to be measured acts directly from the proximal plunger end 11.2 on the measurement element 12.

[0032] The plunger unit 11 has another function of preventing mechanical stress resulting from mounting the pressure sensor 1 in the hole H in the wall W of the pressure chamber C from reaching the measuring element 12 from the housing 20, because such mechanical stress may falsify the measurement of the pressure P. For this purpose, the plunger unit 11 has a preloading body 11.5. In the illustrated embodiment, the preloading body 11.5 is hollow cylindrical. One end of the preloading sleeve 11.3 facing away from the proximal plunger end 11.2 is attached to the preloading body 11.5. By this attachment, the measuring element 12 is arranged under mechanical preloading between the proximal plunger end 11.2 and the preloading body 11.5 on the longitudinal axis A. The term "mechanical preloading" means that mechanical preloading is formed before the actual measurement of the pressure P. Preferably, the amount of mechanical preloading is at least one decimal digit greater than the mechanical stress that may occur by mounting the pressure sensor 1 through the housing 20 in the wall W of the pressure chamber C.

[0033] The preloading sleeve 11.3 is a thin wall with a wall thickness of 0.1 mm or less. The thin-walled preloading sleeve 11.3 enables a high mobility of the plunger 11 and thus a high sensitivity of the pressure sensor 1. It must be prevented that the medium M penetrates into the interior 20.3 of the housing through the gap 30.4 at high temperature T and high pressure P. In the case of an injection molding die, the medium M is a liquid melt, and the liquid melt will harden inside the housing interior 20.3 and thus prevent the plunger 11 from moving. In an internal combustion engine, the medium M is a mixture of fuel and air, and the mixture of fuel and air is chemically aggressive and will corrode the preloading sleeve 11.3 inside the housing interior 20.3 and thus damage or destroy the preloading sleeve 11.3.

[0034] The measuring element 12 has the function of generating a measurement signal S for measuring the pressure P. The measuring element 12 can be a piezoelectric measuring element, a piezoresistive measuring element, a strain gauge, etc. The variable of the measurement signal S is proportional to the measured pressure P.

[0035] The sensor unit 10 includes an electrode arrangement 13, a socket unit 14, socket contacts 15, and an insulator 16.

[0036] The socket unit 14 has the function of accommodating the electrode arrangement 13, the socket contacts 15, and the insulator 16. For this purpose, the socket unit 14 includes a hollow cylindrical socket housing made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. The socket housing is attached to the preloading body 11.5 via a socket housing preloading body connection part on the side of the preloading body 11.5 facing away from the measuring element 12. Inside the socket housing, the socket unit 14 includes a socket chamber. The electrode arrangement 13, the socket contacts 15, and the insulator 16 are arranged inside the socket chamber.

[0037] The electrode arrangement 13 has the function of conducting the measurement signal S from the measuring element 12 to the socket contacts 15. In the illustrated embodiment of the sensor unit 10, the electrode arrangement 13 is cylindrical and made of a conductive material such as copper, silver, gold, etc. The electrode arrangement 13 is arranged at the end of the socket unit 14 facing the measuring element 12 and extends from the socket chamber into the preloading sleeve chamber 11.4. The electrode arrangement 13 is electrically connected to the measuring element 12. The electrode arrangement 13 sends the measurement signal S from the measuring element 12 to the socket contacts 15 along the longitudinal axis A.

[0038] The socket contacts 15 have the function of making the measurement signal S available outside the socket unit 14. In the illustrated embodiment, the socket contacts 15 are cylindrical and made of a conductive material such as copper, silver, gold, etc. The socket contacts 15 are arranged at the end of the socket unit 14 facing away from the measuring element 12. The electrode arrangement 13 and the socket contacts 15 are electrically connected to each other.

[0039] The insulator 16 has the function of electrically insulating the electrode arrangement 13 and the socket contacts 15 from the socket housing. The insulator 16 is in a hollow cylindrical shape and is made of ceramic, Al 2 O3 It is made of an electrically insulating and mechanically rigid material such as ceramic or sapphire. With respect to the longitudinal axis line A, the insulator 16 is arranged radially outside the electrode arrangement 13 and the socket contact 15.

[0040] Therefore, the plunger unit 11 and the measuring element 12 are arranged as part of the sensor unit 10 inside the housing 20.3. The distal plunger end 11.1 protrudes from the housing 20. According to FIG. 1, the distal housing end 20.1 has a housing opening 20.4. The distal plunger end 11.1 protrudes through the housing opening 20.4 to the pressure chamber C.

[0041] According to the present invention, the pressure sensor 1 includes a sleeve 30. The sleeve 30 has a function of accommodating at least one sealing element 40. The sleeve 30 is in a hollow cylindrical shape and is made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. In the illustrated embodiment, the sleeve 30 includes a distal sleeve end 30.1 and a proximal sleeve end 30.2, and the distal sleeve end 30.1 is arranged further away from the measuring element 12 than the proximal sleeve end 30.2 along the longitudinal axis line A.

[0042] Preferably, the distal plunger end 11.1 extends to the distal sleeve end 30.1. The pressure absorption surface 11.11 and the distal sleeve end 30.1 are at a pressure absorption level B perpendicular to the longitudinal axis A. This has the advantage that the pressure P can act only on the distal plunger end 11.1 parallel to the longitudinal axis A via the pressure absorption surface 11.11. This prevents pressure components not parallel to the longitudinal axis A from acting on the distal plunger end 11.1, which, if the measuring element 12 generates an interference signal as such a pressure component not parallel to the longitudinal axis A, can falsify the measurement of the pressure P. Avoiding such pressure components from acting non-parallel to the longitudinal axis A increases the sensitivity and accuracy of the measurement of the pressure P. Alternatively, this has the advantage that the distal plunger end 11.1 and the distal sleeve end 30.1 can be specially adapted to the surface geometry of the wall W of the pressure chamber C by cutting both ends to a predetermined length. Thus, the distal plunger end 11.1 and the distal sleeve end 30.1 can be cut to a predetermined length to form the surface geometry of the wall W of the pressure chamber C that is inclined or curved with respect to the longitudinal axis A.

[0043] The sleeve 30 is attached to the housing 20. Preferably, the sleeve 30 is attached to the distal housing end 20.1 via a sleeve-housing connection 30.3 at the proximal sleeve end 30.2. With respect to the longitudinal axis A, the sleeve-housing connection 30.3 is arranged radially outward at the proximal sleeve end 30.2 and the distal housing end 20.1. The sleeve-housing connection 30.3 is made by welding, soldering, screwing, pressing, adhesion, etc. In the illustrated embodiment, the sleeve-housing connection 30.3 is a welded connection.

[0044] The sleeve 30 surrounds the distal plunger end 11.1 over a certain area. With respect to the longitudinal axis A, the sleeve 30 surrounds the distal plunger end 11.1 radially outward. The distal plunger end 11.1 shows an outer surface. Preferably, the sleeve 30 surrounds the outer surface of the distal plunger end 11.1 radially outward at an angle of 360°.

[0045] The sleeve 30 and the distal plunger end 11.1 are separated by a gap 30.4. Preferably, the gap 30.4 exhibits a width of 0.1 mm or less in the radial direction perpendicular to the longitudinal axis A.

[0046] The sleeve 30 and the housing 20 form at least one groove 50. The groove 50 serves to accommodate the sealing element 40. Preferably, the groove 50 is arranged within the region of the proximal sleeve end 30.2 and the distal housing end 20.1. The sealing element 40 is arranged within the groove 50.

[0047] The sleeve 30 can have a length of several centimeters along the longitudinal axis A. Then, the groove 50 and the sealing element 40 are arranged at a relatively large distance of several centimeters from the pressure chamber C. This has the advantage that, in the case of the medium M at a high temperature T, the temperature T within the wall W and thus also within the sleeve 30 decreases as the distance from the pressure chamber C increases, so that the sealing element 40 is not exposed to the high temperature T of the medium M during the operation of the pressure sensor 1.

[0048] However, along the longitudinal axis A, the sleeve 30 can also have a length of just a few millimeters. Then, the groove 50 and the sealing element 40 are arranged at a relatively short distance of several millimeters from the pressure chamber C. This has the advantage that a medium M having a low viscosity cannot penetrate deep into the gap 30.4 along the longitudinal axis A before this medium encounters the sealing element 40.

[0049] With respect to the longitudinal axis A, the groove 50 is arranged radially inside the sleeve 30 and the housing 20. The groove 50 is annular. The groove 50 comprises a plurality of groove walls 50.1, 50.2, 50.3. At least one of the groove walls 50.1, 50.2, 50.3 is part of the proximal sleeve end 30.2. At least one of the groove walls 50.1, 50.2, 50.3 is part of the distal housing end 20.1.

[0050] In the embodiment of the pressure sensor 1 according to FIG. 1, the groove 50 has a rectangular cross-section and includes three groove walls 50.1, 50.2, and 50.3. Among the three groove walls 50.1, 50.2, and 50.3, the first groove wall 50.1 and the second groove wall 50.2 are part of the proximal sleeve end 30.2, and the third groove wall 50.3 is part of the distal housing end 20.1. The first groove wall 50.1 and the third groove wall 50.3 are straight and are arranged at an angle of 90° with respect to the longitudinal axis A, and the second groove wall 50.2 is straight and is arranged parallel to the longitudinal axis A.

[0051] In the embodiment of the pressure sensor 1 according to FIG. 2, the groove 50 has a triangular cross-section and includes two groove walls 50.1 and 50.2. Among the two groove walls 50.1 and 50.2, the first groove wall 50.1 is part of the proximal sleeve end 30.2, and the second groove wall 50.2 is part of the distal housing end 20.1. The first groove wall 50.1 and the second groove wall 50.2 are arranged inclined with respect to the longitudinal axis A. Preferably, the first groove wall 50.1 and the second groove wall 50.2 are arranged at an angle of 30° with respect to the longitudinal axis A. The two inclined groove walls 50.1 and 50.2 enable precise positioning of the sealing element 40 within the groove 50.

[0052] In the embodiment of the pressure sensor 1 according to FIG. 3, the groove 50 has a trapezoidal cross-section and includes three groove walls 50.1, 50.2, and 50.3. Among the three groove walls 50.1, 50.2, and 50.3, the first groove wall 50.1 and the second groove wall 50.2 are part of the proximal sleeve end 30.2, and the third groove wall 50.3 is part of the distal housing end 20.1. The first groove wall 50.1 and the third groove wall 50.3 are arranged inclined with respect to the longitudinal axis A, and the second groove wall 50.2 is arranged straight and parallel to the longitudinal axis A. Preferably, the first groove wall 50.1 and the third groove wall 50.3 are arranged at an angle of 30° with respect to the longitudinal axis A.

[0053] In the embodiment of the pressure sensor 1 according to FIG. 4, the groove has a circular cross-section and comprises two groove walls 50.1, 50.2. Of the two groove walls 50.1, 50.2, the first groove wall 50.1 is part of the proximal sleeve end 30.2 and the second groove wall 50.2 is part of the distal housing end 20.1. The first groove wall 50.1 is round and curves into the proximal sleeve end 30.2 from the longitudinal axis A. Preferably, the curve shows a constant radius. The second groove wall 50.2 is round and curves into the distal housing end 20.1 from the longitudinal axis A. Preferably, the curve shows a constant radius. The two round groove walls 50.1, 50.2 allow for precise positioning of the sealing element 40 within the groove 50.

[0054] In the embodiment of the pressure sensor 1 according to FIG. 5, the groove is semi-circular and comprises three groove walls 50.1, 50.2, 50.3. Of the three groove walls 50.1, 50.2, 50.3, the first groove wall 50.1 and the second groove wall 50.2 are part of the proximal sleeve end 30.2 and the third groove wall 50.3 is part of the distal housing end 20.1. The first groove wall 50.1 is round and curves into the proximal sleeve end 30.2 from the longitudinal axis A. Preferably, the curve shows a constant radius. The second groove wall 50.2 is straight and is arranged parallel to the longitudinal axis A. The third groove wall 50.3 is straight and is arranged at an angle of 90° to the longitudinal axis A.

[0055] In the embodiment of the pressure sensor 1 according to FIG. 6, the groove is semi-circular and comprises three groove walls 50.1, 50.2, 50.3. Of the three groove walls 50.1, 50.2, 50.3, the first groove wall 50.1 and the second groove wall 50.2 are part of the proximal sleeve end 30.2 and the third groove wall 50.3 is part of the distal housing end 20.1. The first groove wall 50.1 is straight and is arranged at an angle of 90° to the longitudinal axis A. The second groove wall 50.2 is straight and is arranged parallel to the longitudinal axis A. The third groove wall 50.3 is round and curves into the distal housing end 20.1 from the longitudinal axis A. Preferably, the curve shows a constant radius.

[0056] With the knowledge of the present invention, a person skilled in the art can also combine the six embodiments of the grooves shown in FIGS. 1 to 6.

[0057] According to the present invention, the pressure sensor 1 comprises at least one sealing element 40. The sealing element 40 has the function of sealing the gap 30.4. In the context of the present invention, the verb "seal" means that during operation of the pressure sensor 1, the medium M cannot enter the interior 20.3 of the housing through the gap 30.4. Preferably, the sealing element 40 permanently seals the gap 30.4 at a temperature in the range of 100°C to 500°C and at a pressure P in the range of 5 MPa (50 bar) to 500 MPa (5000 bar). The sealing element 40 is toroidal in shape and consists of an elastically sealing material such as an elastomer, in particular a fluoroelastomer or perfluoroelastomer, rubber, in particular acrylonitrile-butadiene rubber.

[0058] In the embodiment shown in the figure, the sealing element 40 has a toroidal seal 40.1 and a toroidal opening 40.2. The toroidal seal 40.1 surrounds the toroidal opening 40.2. The distal plunger end 11.1 projects from the toroidal opening 40.2.

[0059] The sealing element 40 is arranged in the groove 50. The sealing element 40 seals the gap 30.4 using a sealing pressure. The sealing pressure can be applied as an axial sealing pressure along the longitudinal axis A, or as a radial sealing pressure perpendicular to the longitudinal axis A, or as a combination of an axial sealing pressure along the longitudinal axis A and a radial sealing pressure perpendicular to the longitudinal axis A. The sealing element 40 is arranged in the groove 50 with pre-compression. The pre-compression is applied to the sealing element 40 by the groove walls 50.1, 50.2, 50.3. In addition to the pre-compression, the pressure P in the gap 30.4 acts on the sealing element 40 as compression. Thus, the sealing pressure is formed by the pre-compression and the compression.

[0060] With the knowledge of the present invention, a person skilled in the art can also arrange a plurality of sealing elements in one or more grooves. In that case, with respect to the longitudinal axis A, the plurality of sealing elements are arranged continuously and then seal the gap 30.4 several times.

[0061] Figs. 9 to 11 show diagrams of three steps of the method according to the present invention for manufacturing the pressure sensor 1. The diagrams of Figs. 9 to 11 also show the pressure sensor 1 along the longitudinal axis A of the pressure sensor 1.

[0062] In the first step of the method according to the present invention shown in Fig. 9, the housing 20 and the sensor unit 10 are provided, the housing 20 is pushed along the longitudinal axis A above the plunger unit 11 and placed on the sensor unit 10. As a result, the plunger unit 11 enters the housing interior 20.3. Thus, the distal plunger end 11.1 protrudes from the housing opening 20.4. The proximal housing end 20.2 is located on the preloading body 11.5. The housing 20 thus placed on the preloading body 11.5 is fastened to the preloading body 11.5 via the housing preloading body connection 20.5. With respect to the longitudinal axis A, the housing preloading body connection 20.5 is arranged radially outside the housing 20 and the preloading body 11.5. The housing preloading body connection 20.5 is made by welding, soldering, screwing, etc. In the embodiment shown in the figure, the housing preloading body connection 20.5 is a welded connection.

[0063] In the second step of the method according to the present invention shown in Fig. 10, the sealing element 40 is provided, pushed along the longitudinal axis A above the distal plunger end 11.1 and placed on the housing 20. Thereby, the distal plunger end 11.1 protrudes from the toroid opening 40.2.

[0064] In the third step of the method according to the invention shown in FIG. 11, a sleeve 30 is provided and pushed over the distal plunger end 11.1 along the longitudinal axis A and placed on the sealing element 40 and the housing 20. The proximal sleeve end 30.2 rests on the distal housing end 20.1. The sleeve 30 thus placed on the housing 20 is attached to the housing 20 via the sleeve-housing connection 30.3. The sealing element 40 is pre-pressed by the overlapping sleeve 30 and housing 20.

Explanation of Reference Numerals

[0065] 1 Pressure sensor 11 Plunger unit 11.1 Distal plunger end 11.11 Pressure absorption surface 11.2 Proximal plunger end 11.3 Preloading sleeve 11.4 Preloading sleeve chamber 11.5 Preloading body 12 Measuring element 14 Socket unit 10 Sensor unit 13 Electrode arrangement 15 Socket contact 16 Insulator 20 Housing 20.1 Distal housing end 20.2 Proximal housing end 20.3 Inside of housing 20.4 Housing opening 20.5 Housing preloading body connection 30 Sleeve 30.1 Distal sleeve end 30.2 Proximal sleeve end 30.3 Sleeve-housing connection 30.4 Gap 40 Sealing element 40.1 Toroidal seal 40.2 Torus opening 50 Groove 50.1 First groove wall 50.2 Second groove wall 50.3 Third groove wall A Longitudinal axis B Pressure absorption level C Pressure chamber H Hole M Medium P Pressure S Measurement signal T Temperature W Wall

Claims

1. A pressure sensor (1) comprising a housing (20), a plunger unit (11) and a measuring element (12), wherein the housing (20) has an interior of the housing (20.3), the plunger unit (11) and the measuring element (12) are arranged within the interior of the housing (20.3), the plunger unit (11) has a distal plunger end (11.1) and a proximal plunger end (11.2), the distal plunger end (11.1) is arranged on the longitudinal axis (A) of the pressure sensor (1) further away from the measuring element (12) than the proximal plunger end (11.2), the distal plunger end (11.1) protrudes from the housing (20), the proximal plunger end (11.2) is operatively connected to the measuring element (12), and the pressure (P) of a medium (M) extending outside the housing (20) is transmitted to the measuring element (12). In the pressure sensor (1), the pressure sensor (1) comprises a sleeve (30), the sleeve (30) is fastened to the housing (20), the sleeve (30) and the distal plunger end (11.1) are spaced apart from each other by a gap (30.4), and the pressure sensor (1) comprises at least one sealing element (40), and the sealing element (40) seals the gap (30.4) to the interior of the housing (20.3) with respect to the medium (M) using a sealing pressure. A pressure sensor (1), characterized by the above.

2. The pressure sensor (1) according to claim 1, characterized in that the sealing element (40) has a toroidal shape and is made of an elastically sealing material such as an elastomer, in particular a fluoroelastomer or perfluoroelastomer, or rubber, in particular acrylonitrile-butadiene rubber.

3. The pressure sensor (1) according to claim 2, characterized in that the sealing element (40) comprises a toroidal seal (40.1) and a toroidal opening (40.2), the toroidal seal (40.1) surrounds the toroidal opening (40.2), and the distal plunger end (11.1) protrudes from the toroidal opening (40.2).

4. The pressure sensor (1) according to any one of claims 1 to 3, characterized in that the sleeve (30) and the housing (20) form a groove (50) radially inward with respect to the longitudinal axis (A), and the sealing element (40) is arranged in the groove (50).

5. The pressure sensor (1) according to claim 4, characterized in that the groove (50) comprises a plurality of groove walls (50.1, 50.2, 50.3), the groove walls (50.1, 50.2, 50.3) apply pre-compression to the sealing element (40) arranged in the groove (50), and the pressure (P) in the gap (30.4) acts on the sealing element (40) as compression in addition to the pre-compression, and the pre-compression and the compression form the sealing pressure.

6. The pressure sensor (1) according to claim 4, characterized in that the housing (20) comprises a distal housing end (20.1) and a proximal housing end (20.2), the distal housing end (20.1) is arranged further away from the measuring element (12) along the longitudinal axis (A) than the proximal housing end (20.2), the sleeve (30) comprises a distal sleeve end (30.1) and a proximal sleeve end (30.2), the distal sleeve end (30.1) is arranged further away from the measuring element (12) along the longitudinal axis (A) than the proximal sleeve end (30.2), and the groove (50) is arranged in the regions of the distal housing end (20.1) and the proximal sleeve end (30.2).

7. The pressure sensor (1) according to claim 6, characterized in that the groove (50) comprises a plurality of groove walls (50.1, 50.2, 50.3), at least one of the plurality of groove walls (50.1, 50.2) is part of the proximal sleeve end (30.2), and at least one of the plurality of groove walls (50.2, 50.3) is part of the distal housing end (20.1).

8. The pressure sensor (1) according to claim 7, characterized in that the groove (50) has a rectangular or triangular or trapezoidal or round or semi-circular cross-section.

9. The plunger unit (11) comprises a preloading sleeve (11.3) and a preloading body (11.5), the proximal plunger end (11.2) merges with the preloading sleeve (11.3), the preloading sleeve (11.3) surrounds a preloading sleeve chamber (11.4), the measuring element (12) is arranged within the preloading sleeve chamber (11.4), an end of the preloading sleeve (11.3) facing away from the proximal plunger end (11.2) is fastened to the preloading body (11.5), and the measuring element (12) is arranged on the longitudinal axis (A) between the proximal plunger end (11.2) and the preloading body (11.5) under mechanical preloading. The pressure sensor (1) according to any one of claims 1 to 8, characterized in that.

10. The pressure sensor (1) can be fastened via the housing (20) in a hole (H) in a wall (W) of a pressure chamber (C), the pressure chamber (C) is arranged in an injection molding die or in an internal combustion engine, and the pressure (P) is in the range of 5 MPa (50 bar) to 500 MPa (5000 bar). The pressure sensor (1) according to any one of claims 1 to 9, characterized in that.

11. A method of manufacturing a pressure sensor (1) comprising a housing (20), a plunger unit (11) and a measuring element (12), wherein the housing (20) comprises a housing interior (20.3), the plunger unit (11) and the measuring element (12) are arranged within the housing interior (20.3), the plunger unit (11) comprises a distal plunger end (11.1) and a proximal plunger end (11.2), the distal plunger end (11.1) is arranged further away from the measuring element (12) than the proximal plunger end (11.2) on the longitudinal axis (A) of the pressure sensor (1), the distal plunger end (11.1) protrudes from the housing (20), the proximal plunger end (11.2) is operably connected to the measuring element (12), and the pressure (P) of a medium (M) extending outside the housing (20) is transmitted to the measuring element (12). In the method, In a first step of the method, a sensor unit (10) having the housing (20), a plunger unit (11) and a measuring element (12) is provided, the housing (20) is pushed onto the plunger unit (11) along the longitudinal axis (A), and is placed on the sensor unit (10). In a second step of the method, at least one sealing element (40) is provided, the sealing element (40) is pushed onto the distal plunger end (11.1) along the longitudinal axis (A), and is placed on the housing (20), and In a third step of the method, a sleeve (30) is provided, the sleeve (30) is pushed onto the distal plunger end (11.1) along the longitudinal axis (A), and is placed on the sealing element (40) and the housing (20), the sleeve (30) and the distal plunger end (11.1) are spaced apart from each other by a gap (30.4), and the sealing element (40) seals the gap (30.4) to the interior (20.3) of the housing against the medium (M) with a sealing pressure. A method, characterized in that.

12. In the first step of the method, the housing (20) placed on the preloading body (11.5) is fastened to the preloading body (11.5) via a housing preloading body connection (20.5), and the housing preloading body connection (20.5) is arranged radially outside the housing (20) and on the preloading body (11.5) with respect to the longitudinal axis (A). The method according to claim 11, characterized in that.

13. In the third step of the method, a groove (50) is formed radially inside the sleeve (30) and on the housing (20) with respect to the longitudinal axis (A) by placing the sleeve (30) on the housing (20) around the sealing element (40). The method according to any one of claims 11 or 12, characterized in that.

14. In the third step of the method, the sealing element (40) is pre-pressed by the overlapping sleeve (30) and the housing (20). The method according to any one of claims 11 to 13, characterized in that.

15. In the third step of the method, the sleeve (30) placed on the housing (20) is fastened to the housing (20) via a connection portion (30.3) between the sleeve and the housing, and the connection portion (30.3) between the sleeve and the housing is arranged radially outside the sleeve (30) and on the housing (20) with respect to the longitudinal axis (A), the method according to any one of claims 11 to 14.

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