Pressure sensor and method for manufacturing a 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 comprises 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 a temperature of several hundred °C and a pressure 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 with respect 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 therein, 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 some 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 pressure. In particular, under high pressures exceeding 100 MPa (1000 bar), the annular diaphragm is positioned in a thicker configuration to ensure a longer lifespan, which then forms a significant force shunt. The annular diaphragm is welded to the housing and plunger, also forming a vibrating system, which is excited and vibrates during pressure measurement, and this vibration can distort the pressure measurement. Finally, the location of the welded joint of the annular diaphragm in the gap between the housing and 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] International Publication No. 2006 / 032152(A1) [Overview of the project] [Problems that the invention aims to solve]

[0006] The first objective of the present invention is to provide a pressure sensor that measures the pressure to be measured with high sensitivity and accuracy. In particular, the pressure sensor should also be able to measure high pressures exceeding 100 MPa (1000 bar) with high sensitivity and accuracy. Another objective is to demonstrate a simple and cost-effective method for manufacturing the pressure sensor. [Means for solving the problem]

[0007] At least one of the objectives is resolved 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 comprises an interior housing, the plunger unit and the measuring element are arranged inside the housing, the plunger unit comprises a distal plunger end and a proximal plunger end, the distal plunger end is positioned further away from the measuring element than the proximal plunger end on the longitudinal axis of the pressure sensor, the distal plunger end protrudes from the housing, and the proximal plunger end is operably connected to the measuring element and transmits the pressure of a medium spreading outside the housing to the measuring element, wherein the pressure sensor comprises a sleeve, the sleeve is attached to the housing, the sleeve and the distal plunger end are separated from each other by a gap, and the pressure sensor comprises at least one sealing element, the sealing element sealing the gap to the medium and into the housing using 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 comprises an interior housing, the plunger unit and the measuring element are arranged inside the housing, the plunger unit comprises a distal plunger end and a proximal plunger end, the distal plunger end is positioned 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, and the proximal plunger end is operably connected to the measuring element and transmits the pressure of a medium spreading outside the housing to the measuring element, wherein the first step of the method is to manufacture a housing A sensor unit having a plunger unit and a measuring element is provided, the housing is pressed over the plunger unit along a 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 pressed over the distal plunger end along a longitudinal axis and placed on the housing; in a third step of the method, a sleeve is provided, pressed over the distal plunger end along a longitudinal axis and placed on the sealing element and the housing, the sleeve and the distal plunger end are separated from each other by a gap, and the sealing element seals the gap to the inside of the housing with sealing pressure to a medium.

[0010] In contrast to the teachings of International Publication No. 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 sealing pressure, thereby the pressure to be measured is transmitted almost completely from the plunger to the measuring element, achieving high sensitivity and accuracy when measuring the pressure.

[0011] An advantageous development of the object of the present invention is claimed in the dependent claims.

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

[0013] In contrast to the teachings in International Publication No. 2006 / 032152(A1), a sealing element made of elastic material does not represent a vibrating system that can be excited and vibrate during pressure measurement, and this vibration can falsify the pressure measurement. By avoiding such vibrations, it becomes possible to measure pressure with high sensitivity and accuracy.

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

[0015] The production of grooves for housing sealing elements is simple and inexpensive.

[0016] In another advantageous development, the groove comprises multiple groove walls, which pre-compress a sealing element placed within the groove, and the pressure within the gap acts on the sealing element as a compression added to the pre-compression, so that the pre-compression and compression form a sealing pressure.

[0017] The two-stage sealing process, involving pre-compression and compression, ensures that even under low pressure, the medium cannot enter the housing through the gap, thus preventing damage or destruction of the measuring element at that location. The production of the groove for pre-pressure in the sealing element is simple and inexpensive.

[0018] In another advantageous development, the groove may have a rectangular, triangular, trapezoidal, round, or semicircular cross-section.

[0019] These various cross-sectional geometries allow for adjustment of the amount of precompression applied by the groove walls on a torus-shaped sealing element. For a sealing element of given dimensions, higher precompression is achieved with groove walls inclined relative to the longitudinal axis, or with rounded groove walls curved inward into the sleeve or housing relative to the longitudinal axis, compared to groove walls straight relative 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 housing through the gap. Manufacturing various groove geometries is simple and inexpensive.

[0020] In another advantageous configuration, the plunger unit comprises a preload sleeve and a preload body, the proximal plunger end joins the preload sleeve, the preload sleeve surrounds a preload sleeve chamber, a measuring element is positioned within the preload sleeve chamber, the end of the preload sleeve facing away from the proximal plunger end is fastened to the preload body via a material-locking preload sleeve-preload body connection, and the measuring element is positioned on the longitudinal axis between the proximal plunger end and the preload body under mechanical preload.

[0021] This design prevents mechanical stress resulting from mounting the pressure sensor within the pressure chamber wall from reaching the measuring element from the housing and distorting the pressure measurement. Preventing the transmission of such mechanical stress improves the sensitivity and accuracy of the pressure measurement.

[0022] The present invention will be described in more detail below with reference to several embodiments with reference to the figures. [Brief explanation of the drawing]

[0023] [Figure 1] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a rectangular groove 50. [Figure 2] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a triangular groove 50. [Figure 3] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a trapezoidal groove 50. [Figure 4] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a circular groove 50. [Figure 5] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a semi-circular groove 50. [Figure 6] A partial cross-sectional view of the pressure sensor 1 according to the present invention, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40 within a semi-circular groove 50. [Figure 7] A cross-sectional view of the sensor unit 10 of the pressure sensor 1 according to the present invention shown in FIGS. 1 to 6. [Figure 8] An exploded view of a part of the components of the pressure sensor 1 according to the present invention shown in FIGS. 1 to 6, including a sensor unit 10, a housing 20, a sleeve 30, and a sealing element 40. [Figure 9] A view of the first step of the method for manufacturing the pressure sensor 1 according to the present invention shown in FIGS. 1 to 6, in which the housing 20 is placed on the sensor unit 10. [Figure 10] A view of the second step of the method for manufacturing the pressure sensor 1 according to the present invention shown in FIG. 9, in which the sealing element 40 is placed on the housing 20. [Figure 11]Figure 10 shows a third step in the method for manufacturing a pressure sensor 1 according to the present invention, in which the sleeve 30 is placed on the sealing element 40 and the housing 20. [Modes for carrying out the invention]

[0024] In the diagram above, the same reference number represents the same object.

[0025] Figures 1 to 6 show cross-sectional views of some embodiments of the pressure sensor 1 according to the present invention. The pressure sensor 1 has the function of measuring the pressure P of a medium M in a pressure chamber C. The pressure chamber C can be located in an injection molding die, an internal combustion engine, etc. In an injection molding die, the medium M is a liquid molten material such as plastic or metal. In an 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 Figures 1 to 6.

[0026] The pressure sensor 1 comprises a sensor unit 10. The sensor unit 10 has the function of housing the measuring element 12. Although only a portion of the sensor unit 10 is shown in Figures 1 to 6, the sensor unit 10 is fully shown in the cross-sectional view in Figure 7 and the exploded view in Figure 8.

[0027] The pressure sensor 1 is shown along vertical axis A. Figures 1 to 8 show the pressure sensor 1 along vertical axis A.

[0028] The pressure sensor 1 comprises a housing 20. The housing 20 has the function of fastening the sensor unit 10 into a hole H in the wall W of the pressure chamber C. The pressure sensor 1 is fastened to the hole H via the housing 20 using a screw connection. The screw connection is not shown in the figure.

[0029] In the embodiment shown in the figure, the housing 20 is hollow cylindrical and made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, or iron alloy. As clearly seen in Figure 8, the housing 20 comprises a distal housing end 20.1 and a proximal housing end 20.2, with the distal housing end 20.1 positioned further away from the measuring element 12 than the proximal housing end 20.2 on the longitudinal axis A. The housing 20 comprises 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 located within the housing interior 20.3.

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

[0031] The plunger unit 11 has a first function: to receive the pressure P to be measured and transmit this pressure to the measuring element 12. For this purpose, the plunger unit 11 has a distal plunger end 11.1, a proximal plunger end 11.2, and a preload sleeve 11.3. The plunger unit 11 is made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, or iron alloy. In the embodiment shown in the figure, the distal plunger end 11.1, the proximal plunger end 11.2, and the preload sleeve 11.3 are integrally formed. The distal plunger end 11.1 and the proximal plunger end 11.2 are cylindrical and meet each other. The proximal plunger end 11.2 meets the preload sleeve 11.3. The preload sleeve 11.3 is a hollow cylinder and surrounds the preload sleeve chamber 11.4. The measuring element 12 is placed inside the preload sleeve chamber 11.4. The distal plunger end 11.1 is positioned on the longitudinal axis A, further away from the measuring 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 the pressure absorbing surface 11.11. The pressure P to be measured acts on the distal plunger end 11.1 via the pressure absorbing surface 11.11 and is transmitted from the distal plunger end 11.1 to the proximal plunger end 11.2. The pressure P to be measured then acts directly on the measuring element 12 from the proximal plunger end 11.2.

[0032] The plunger unit 11 has another function: to prevent 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 this type of mechanical stress can falsify the measurement of pressure P. For this purpose, the plunger unit 11 has a preload 11.5. In the embodiment shown in the figure, the preload 11.5 is a hollow cylinder. One end of a preload sleeve 11.3, which faces away from the proximal plunger end 11.2, is attached to the preload 11.5. This attachment positions the measuring element 12 on the longitudinal axis A under mechanical preload between the proximal plunger end 11.2 and the preload 11.5. The term "mechanical preload" means that a mechanical preload is formed before the actual measurement of the pressure P. Preferably, the amount of mechanical preload is at least one decimal place greater than the mechanical stress that may occur from mounting the pressure sensor 1 through the housing 20 in the wall W of the pressure chamber C.

[0033] The preload sleeve 11.3 has a thin wall with a wall thickness of 0.1 mm or less. The thin wall of the preload sleeve 11.3 allows for high mobility of the plunger 11 and therefore high sensitivity of the pressure sensor 1. The penetration of the medium M into the housing interior 20.3 through the gap 30.4 at high temperature T and high pressure P must be prevented. In the case of an injection mold, the medium M is a liquid molten material, which will harden inside the housing interior 20.3 and therefore prevent the plunger 11 from moving. In an internal combustion engine, the medium M is a mixture of fuel and air, which is chemically aggressive and will corrode the preload sleeve 11.3 inside the housing interior 20.3, thus damaging or destroying the preload sleeve 11.3.

[0034] The measuring element 12 has the function of generating a measurement signal S for measuring 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 comprises an electrode arrangement 13, a socket unit 14, a socket contact 15, and an insulator 16.

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

[0037] The electrode arrangement 13 has the function of conducting the measurement signal S from the measurement element 12 to the socket contact 15. In the embodiment of the sensor unit 10 shown in the figure, the electrode arrangement 13 is cylindrical and made of a conductive material such as copper, silver, or gold. The electrode arrangement 13 is located at the end of the socket unit 14 facing the measurement element 12 and extends from the socket chamber into the pre-pressure sleeve chamber 11.4. The electrode arrangement 13 is electrically connected to the measurement element 12. The electrode arrangement 13 transmits the measurement signal S from the measurement element 12 to the socket contact 15 along the vertical axis A.

[0038] The socket contact 15 has the function of making the measurement signal S available outside the socket unit 14. In the embodiment shown in the figure, the socket contact 15 is cylindrical and made of a conductive material such as copper, silver, or gold. The socket contact 15 is positioned at the end of the socket unit 14 facing away from the measurement element 12. The electrode arrangement 13 and the socket contact 15 are electrically connected to each other.

[0039] The insulator 16 has the function of electrically insulating the electrode arrangement 13 and the socket contact 15 from the socket housing. The insulator 16 is hollow cylindrical in shape and is made of an electrically insulating and mechanically rigid material such as ceramic, Al2O3 ceramic, or sapphire. With respect to the vertical axis A, the insulator 16 is positioned radially outward from 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 Figure 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 comprises a sleeve 30. The sleeve 30 has the function of housing at least one sealing element 40. The sleeve 30 is hollow cylindrical in shape and is made of a mechanically resistant material such as pure metal, nickel alloy, cobalt alloy, or iron alloy. In the embodiment shown in the figure, the sleeve 30 comprises a distal sleeve end 30.1 and a proximal sleeve end 30.2, the distal sleeve end 30.1 is positioned further away from the measuring element 12 than the proximal sleeve end 30.2 along the longitudinal axis 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 pressure P can only act 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 could falsify the measurement of pressure P if the measuring element 12 generates an interference signal as such a pressure component not parallel to the longitudinal axis A. Avoiding such pressure components acting non-parallel to the longitudinal axis A improves the sensitivity and accuracy of the pressure P measurement. Alternatively, this has the advantage that the distal plunger end 11.1 and the distal sleeve end 30.1 can be specifically adapted to the surface geometry of the wall W of the pressure chamber C by cutting both ends to a predetermined length. Therefore, the distal plunger end 11.1 and the distal sleeve end 30.1 can be cut to a predetermined length to create a surface geometry of the wall W of the pressure chamber C that is inclined or curved with respect to the vertical 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 at the proximal sleeve end 30.2 via a sleeve-to-housing connection 30.3. With respect to the vertical axis A, the sleeve-to-housing connection 30.3 is radially positioned outward at the proximal sleeve end 30.2 and the distal housing end 20.1. The sleeve-to-housing connection 30.3 is made by welding, soldering, screwing, pressurizing, bonding, etc. In the embodiment shown in the figure, the sleeve-to-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 vertical axis A, the sleeve 30 surrounds the distal plunger end 11.1 radially on the outside. The distal plunger end 11.1 shows the outer surface. Preferably, the sleeve 30 surrounds the outer surface of the distal plunger end 11.1 radially at an angle of 360° on the outside.

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

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

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

[0048] However, along the longitudinal axis A, the sleeve 30 can also be only a few millimeters long. Then, the groove 50 and the sealing element 40 are positioned at a relatively short distance of a few millimeters from the pressure chamber C. This has the advantage that the low-viscosity medium M cannot penetrate deep into the gap 30.4 along the longitudinal axis A before encountering the sealing element 40.

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

[0050] In the embodiment of the pressure sensor 1 shown in Figure 1, the groove 50 has a rectangular cross-section and comprises three groove walls 50.1, 50.2, and 50.3. Of 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 positioned at a 90° angle with respect to the vertical axis A, while the second groove wall 50.2 is straight and positioned parallel to the vertical axis A.

[0051] In the embodiment of the pressure sensor 1 shown in Figure 2, the groove 50 has a triangular cross-section and comprises two groove walls 50.1 and 50.2. Of 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 at an inclination 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 allow for precise positioning of the sealing element 40 within the groove 50.

[0052] In the embodiment of the pressure sensor 1 shown in Figure 3, the groove 50 has a trapezoidal cross-section and comprises three groove walls 50.1, 50.2, and 50.3. Of 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 at an inclination with respect to the vertical axis A, while the second groove wall 50.2 is arranged straight and parallel to the vertical 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 vertical axis A.

[0053] In the embodiment of the pressure sensor 1 shown in Figure 4, the groove has a circular cross-section and comprises two groove walls 50.1 and 50.2. Of 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 is round and curves inward from the vertical axis A into the proximal sleeve end 30.2. Preferably, the curve exhibits a constant radius. The second groove wall 50.2 is round and curves inward from the vertical axis A into the distal housing end 20.1. Preferably, the curve exhibits a constant radius. The two round groove walls 50.1 and 50.2 enable precise positioning of the sealing element 40 within the groove 50.

[0054] In the embodiment of the pressure sensor 1 shown in Figure 5, the groove is semicircular and comprises three groove walls 50.1, 50.2, and 50.3. Of 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 is round and curves inward from the vertical axis A into the proximal sleeve end 30.2. Preferably, the curve exhibits a constant radius. The second groove wall 50.2 is straight and positioned parallel to the vertical axis A. The third groove wall 50.3 is straight and positioned at a 90° angle with respect to the vertical axis A.

[0055] In the embodiment of the pressure sensor 1 shown in Figure 6, the groove is semicircular and comprises three groove walls 50.1, 50.2, and 50.3. Of 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 is straight and positioned at a 90° angle with respect to the vertical axis A. The second groove wall 50.2 is straight and positioned parallel to the vertical axis A. The third groove wall 50.3 is round and curves inward from the vertical axis A into the distal housing end 20.1. Preferably, the curvature exhibits a constant radius.

[0056] Those skilled in the art can also combine the six embodiments of the grooves shown in Figures 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 sense of the present invention, the verb "seal" means that the medium M cannot enter the housing interior 20.3 through the gap 30.4 during operation of the pressure sensor 1. Preferably, the sealing element 40 permanently seals the gap 30.4 at a temperature in the range of 100°C to 500°C and 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 is made of an elastically sealing material such as an elastomer, particularly a fluoroelastomer or perfluoroelastomer, or a rubber, particularly acrylonitrile butadiene rubber.

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

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

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

[0061] Figures 9 to 11 illustrate the three steps of the method according to the present invention for manufacturing a pressure sensor 1. The diagrams in Figures 9 to 11 also show the pressure sensor 1 along the vertical axis A of the pressure sensor 1.

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

[0063] In the second step of the method according to the present invention, shown in Figure 10, a sealing element 40 is provided and pressed over the distal plunger end 11.1 along the longitudinal axis A and placed on the housing 20. Thereafter, the distal plunger end 11.1 protrudes from the torus opening 40.2.

[0064] In the third step of the method according to the present invention shown in Figure 11, a sleeve 30 is provided and pressed over the distal plunger end 11.1 along the longitudinal axis A, and placed on the sealing element 40 and 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 a sleeve-to-housing connection 30.3. The sealing element 40 is pre-pressed by the overlapping sleeve 30 and housing 20. [Explanation of Symbols]

[0065] 1. Pressure sensor 11 Plunger Unit 11.1 Distal plunger end 11.11 Pressure Absorption Surface 11.2 Proximal plunger end 11.3 Preloaded sleeve 11.4 Pre-pressure sleeve chamber 11.5 Preloading element 12 measurement elements 14 Socket Units 10 Sensor Units 13 Electrode arrangement 15 Socket contacts 16 Insulator 20 Housing 20.1 Distal housing end 20.2 Proximal Housing End 20.3 Inside the Housing 20.4 Housing opening 20.5 Housing preload connection section 30 sleeves 30.1 Distal sleeve end 30.2 Proximal sleeve end 30.3 Connection between sleeve and housing 30.4 Gap 40 sealing elements 40.1 Toroidal Sealing 40.2 Torus opening 50 grooves 50.1 First trench wall 50.2 Second trench wall 50.3 Third trench wall A Vertical 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) comprises a housing interior (20.3), the plunger unit (11) and the measuring element (12) are arranged within the housing interior (20.3), and the plunger unit (11) comprises a distal plunger end (11.1) and a proximal plunger end (11.2), and the distal plunger end (11. 1) In a pressure sensor (1) wherein the pressure sensor (1) is positioned on the vertical axis (A) of the pressure sensor (1) at a distance greater than the proximal plunger end (11.2) from the measuring element (12), the distal plunger end (11.1) protrudes from the housing (20), and the proximal plunger end (11.2) is operably connected to the measuring element (12) and transmits the pressure (P) of a medium (M) spreading outside the housing (20) to the measuring element (12), 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 separated from each other by a gap (30.4), the pressure sensor (1) comprises at least one sealing element (40), the sealing element (40) seals the gap (30.4) to the inside of the housing (20.3) with sealing pressure, the sleeve (30) and the housing (20) form a groove (50) radially inward with respect to the longitudinal axis (A), the sealing element (40) is positioned within the groove (50), The plunger unit (11) comprises a preload sleeve (11.3) and a preload body (11.5), the proximal plunger end (11.2) merges with the preload sleeve (11.3), the preload sleeve (11.3) surrounds a preload sleeve chamber (11.4), the measuring element (12) is positioned within the preload sleeve chamber (11.4), the end of the preload sleeve (11.3) facing away from the proximal plunger end (11.2) is fastened to the preload body (11.5), and the measuring element (12) is positioned on the vertical axis (A) between the proximal plunger end (11.2) and the preload body (11.5) under mechanical preload. A pressure sensor (1) characterized by the following.

2. The pressure sensor (1) according to claim 1, characterized in that the sealing element (40) is toroidal in shape and made of an elastic sealing material.

3. The pressure sensor (1) according to claim 2, characterized in that the elastically sealing material is a fluoroelastomer, a perfluoroelastomer, or acrylonitrile butadiene rubber.

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

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) disposed within the groove (50), and the pressure (P) in the gap (30.4) acts on the sealing element (40) as compression applied 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 positioned further away from the measuring element (12) than the proximal housing end (20.2) along the vertical axis (A), the sleeve (30) comprises a distal sleeve end (30.1) and a proximal sleeve end (30.2), the distal sleeve end (30.1) is positioned further away from the measuring element (12) than the proximal sleeve end (30.2) along the vertical axis (A), and the groove (50) is positioned within the region 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, triangular, trapezoidal, round, or semicircular cross-section.

9. The pressure sensor (1) according to any one of claims 1 to 8, characterized in that the pressure sensor (1) can be fastened through the housing (20) into a hole (H) in the wall (W) of the pressure chamber (C), the pressure chamber (C) is located inside an injection molding die or an internal combustion engine, and the pressure (P) is in the range of 5 MPa (50 bar) to 500 MPa (5000 bar).

10. A method for 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), and the distal plunger In a method in which the end portion (11.1) is positioned on the vertical axis (A) of the pressure sensor (1) and further away from the measuring element (12) than the proximal plunger end portion (11.2), the distal plunger end portion (11.1) protrudes from the housing (20), and the proximal plunger end portion (11.2) is operably connected to the measuring element (12) and transmits the pressure (P) of a medium (M) spreading outside the housing (20) to the measuring element (12), The plunger unit (11) is characterized in that it comprises a preload sleeve (11.3) and a preload body (11.5), the proximal plunger end (11.2) merges with the preload sleeve (11.3), the preload sleeve (11.3) surrounds a preload sleeve chamber (11.4), the measuring element (12) is positioned within the preload sleeve chamber (11.4), the end of the preload sleeve (11.3) facing away from the proximal plunger end (11.2) is fastened to the preload body (11.5), and the measuring element (12) is positioned on the vertical axis (A) between the proximal plunger end (11.2) and the preload body (11.5) under mechanical preload, and further In the first step of the method described above, a sensor unit (10) having a plunger unit (11) and a measuring element (12), and a housing (20) are provided, wherein the housing (20) is pressed over the plunger unit (11) along the vertical axis (A) and placed on the sensor unit (10), In the second step of the method described above, at least one sealing element (40) is provided, the sealing element (40) is pressed on the distal plunger end (11.1) along the longitudinal axis (A) and placed on the housing (20), and In the third step of the method described above, a sleeve (30) is provided and pressed over the distal plunger end (11.1) along the longitudinal axis (A), and placed on the sealing element (40) and the housing (20), such that the sleeve (30) and the distal plunger end (11.1) are separated from each other by a gap (30.4), and the sealing element (40) seals the gap (30.4) to the medium (M) into the housing interior (20.3) with sealing pressure. A method characterized by the following.

11. The method according to claim 10, characterized in that, in the first step of the method described above, the housing (20) placed on the preload body (11.5) is fastened to the preload body (11.5) via a housing preload body connection portion (20.5), and the housing preload body connection portion (20.5) is radially positioned on the outside of the housing (20) and on the preload body (11.5) with respect to the vertical axis (A).

12. The method according to claim 10 or 11, characterized in that, in the third step of the method, the groove (50) is formed radially on the inside of 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).

13. The method according to claim 10 or 11, characterized in that, in the third step of the method, the sealing element (40) is pre-pressed by the overlapping sleeve (30) and housing (20).

14. The method according to claim 10 or 11, characterized in that, in the third step of the method described above, the sleeve (30) placed on the housing (20) is fastened to the housing (20) via a sleeve-to-housing connection portion (30.3), and the sleeve-to-housing connection portion (30.3) is radially positioned on the outside of the sleeve (30) and on the housing (20) with respect to the vertical axis (A).

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