Pressure sensor and manufacturing method thereof

Abstract

A pressure sensor (1) has a housing (20), a plunger unit (11) and a measuring element (12); the housing has a housing interior (20.3) in which the plunger unit and the measuring element are arranged; the plunger unit has a distal plunger end (11.1) and a proximal plunger end (11.2), the distal plunger end being arranged farther from the measuring element along a longitudinal axis (A) of the pressure sensor than the proximal plunger end, and the distal plunger end projecting from the housing, and the proximal plunger end is in operative connection with the measuring element and transfers the pressure (P) of a medium (M) present outside the housing to the measuring element; the pressure sensor has a sleeve (30) which is fastened to the housing; the sleeve and the distal plunger end are spaced apart from each other by a gap (30.4); the pressure sensor has at least one sealing element (40) which presses the sealing gap by means of the seal to prevent the medium from going into the housing interior.

Description

Technical Field

[0001] The invention relates to a pressure sensor and a method for producing the pressure sensor. Background Art

[0002] Pressure sensors are used in various technical applications. Document WO2006 / 032152A1 shows a pressure sensor for measuring the current pressure in a pressure chamber of an injection mold or an internal combustion engine. The pressure sensor has a housing, a plunger and a measuring element. The housing has a housing inner cavity, and the plunger and the measuring element are arranged in the housing inner cavity. The plunger has a distal plunger end and a proximal plunger end relative to the measuring element. The plunger is in effective connection with the measuring element through the proximal plunger end. The pressure sensor can be fastened in a hole in the wall of the pressure chamber through the housing. When the pressure sensor is fastened in the hole, the distal plunger end extends out of the housing into the pressure chamber. The pressure to be measured is transmitted from the distal plunger end to the proximal plunger end and acts on the measuring element.

[0003] In an injection mold, the medium in the pressure chamber is a liquid melt formed by plastic, metal, etc., or a fuel-air mixture in an internal combustion engine. The medium can have a temperature of several hundred degrees Celsius and a pressure of several hundred bars. In order to make the pressure sensor have high sensitivity when measuring pressure, the plunger is movably arranged relative to the housing, which is achieved by the gap between the housing and the plunger. And in order to prevent the medium from entering the inner cavity of the housing through the gap and damaging or destroying the measuring element there, the document WO2006 / 032152A1 teaches the arrangement of a metal annular membrane in the gap, which is attached to the plunger and the housing by a welding connection and seals the gap.

[0004] However, the welded connection of the annular diaphragm also forms a force bypass, through which part of the pressure to be measured passes from the plunger to the housing, and thus reduces the sensitivity of the pressure sensor when measuring pressure. In particular, under high pressures exceeding 1000 bar, in order to ensure a long service life, the annular diaphragm is designed to be very thick and thus forms a significant force bypass. The annular diaphragm welded to the housing and the plunger also forms a vibration system and is excited to vibrate during the pressure measurement process, which vibration may distort the pressure measurement. Finally, the welding connection location of the annular diaphragm in the gap between the housing and the plunger is difficult for welding tools to reach, which makes it complicated and expensive to complete the welding connection. Summary of the invention

[0005] A first object of the present invention is to provide a pressure sensor which measures the pressure to be measured with high sensitivity and high accuracy. In particular, the pressure sensor should be able to measure high pressures exceeding 1000 bar with high sensitivity and high accuracy. Another object of the present invention is to provide a method for manufacturing the pressure sensor in a simple and low-cost manner.

[0006] At least one of the above-mentioned purposes of the present invention is achieved by the technical solution according to the present invention.

[0007] The present invention relates to a pressure sensor, which comprises a housing, a plunger unit and a measuring element; the housing comprises an inner cavity of the housing, and the plunger unit and the measuring element are arranged in the inner cavity of the housing; the plunger unit comprises a distal plunger end and a proximal plunger end, the distal plunger end is arranged to be farther away from the measuring element than the proximal plunger end on the longitudinal axis of the pressure sensor, the distal plunger end extends out of the housing, and the proximal plunger end is effectively connected to the measuring element and transmits the medium pressure outside the housing to the measuring element; wherein the pressure sensor comprises a sleeve, which is fastened to the housing; wherein the sleeve and the distal plunger end are separated from each other by a gap; and wherein the pressure sensor comprises at least one sealing element, which seals the gap by sealing extrusion (Dichtpressung) to prevent the medium from going to the inner cavity of the housing.

[0008] The present invention also relates to a method for manufacturing a pressure sensor, the pressure sensor having a housing, a plunger unit and a measuring element; the housing having a housing inner cavity, and the plunger unit and the measuring element are arranged in the housing inner cavity; the plunger unit has a distal plunger end and a proximal plunger end, the distal plunger end is arranged to be farther away from the measuring element than the proximal plunger end on the longitudinal axis of the pressure sensor, and the distal plunger end extends from the housing, and the proximal plunger end is effectively connected to the measuring element and transmits the medium pressure outside the housing to the measuring element; wherein, in a first method step, a housing is provided A body and a sensor unit having a plunger unit and a measuring element, and the housing is pushed onto the plunger unit along the longitudinal axis and placed on the sensor unit; in a second method step, at least one sealing element is provided, and the sealing element is pushed onto the distal plunger end along the longitudinal axis and placed on the housing; and in a third method step, a sleeve is provided and pushed onto 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 by a gap, and the sealing element seals the gap by sealing extrusion to prevent the medium from entering the housing cavity.

[0009] Different from the teaching of document WO2006 / 032152A1, the present invention avoids force bypass when sealing the gap between the plunger and the housing. The gap is sealed by sealing and squeezing, thereby allowing the pressure to be measured to be basically completely transmitted from the plunger to the measuring element, achieving high sensitivity and high precision of pressure measurement.

[0010] Preferred embodiments of the present invention are given below.

[0011] In a preferred embodiment, the sealing element is in the form of a torus. And it is made of elastic sealing material, such as elastomer, especially fluoroelastomer or perfluoroelastomer, or rubber, especially acrylonitrile-butadiene rubber.

[0012] Another difference from the teaching of document WO2006 / 032152A1 is that the sealing element made of elastic material is not a vibration system, which may be excited to vibrate during the pressure measurement process, and such vibration may distort the pressure measurement. Avoiding such vibration can achieve pressure measurement with high sensitivity and high accuracy.

[0013] In a further preferred embodiment, in the third method step, the groove is formed on the radial inner side of the sleeve and on the housing by placing the sleeve on the housing around the sealing element with respect to the longitudinal axis.

[0014] Such a groove for accommodating a sealing element is simple and cost-effective to produce.

[0015] In another preferred extension, the groove has a plurality of groove walls; wherein the plurality of groove walls pre-press a sealing element arranged in the groove; and wherein the pressure in the gap acts on the sealing element as a pressure press in addition to the pre-press, and the pre-press and the pressure press together form a sealing press.

[0016] This secondary seal of pre-compression and pressure compression ensures that even under low pressure no medium can enter the housing cavity through the gap and damage or destroy the measuring element there. This groove for pre-stressing the sealing element is simple and cost-effective to manufacture.

[0017] In another preferred embodiment, the cross section of the recess is rectangular, triangular, trapezoidal, circular or semicircular.

[0018] By means of these different cross-sectional geometries, the degree of pre-compression exerted by the groove wall on the toroidal sealing element can be adjusted. For a sealing element of a given size, a groove wall inclined relative to the longitudinal axis or a circular groove wall raised relative to the longitudinal axis in the sleeve or housing enables a stronger pre-compression than a groove wall straight relative to the longitudinal axis. As a result, the pressure sensor can operate even at high pressures of more than 1000 bar without the medium entering the housing cavity through the gap. Grooves of different geometries are simple and cost-effective to manufacture.

[0019] In another preferred extension, the plunger unit has a preload sleeve and a preload body; wherein the proximal plunger end is integrated into the preload sleeve; wherein the preload sleeve surrounds a preload sleeve space, in which a measuring element is arranged; wherein the end of the preload sleeve facing away from the proximal plunger end is fastened to the preload body by a material-fitted preload sleeve-preload body connection; and wherein the measuring element is arranged along the longitudinal axis between the proximal plunger end and the preload body under mechanical preload.

[0020] This embodiment prevents mechanical stresses from being transmitted from the housing to the measuring element due to the fastening of the pressure sensor in the wall of the pressure chamber and possibly falsifying the pressure measurement. Preventing the transmission of such mechanical stresses can increase the sensitivity and precision of the pressure measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in detail below with reference to the accompanying drawings and based on various embodiments.

[0022] Figure 1 shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a rectangular recess 50 ;

[0023] Figure 2 shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a triangular groove 50 ;

[0024] Figure 3 shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a trapezoidal groove 50 ;

[0025] Figure 4 shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a circular groove 50 ;

[0026] Figure 5shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a semicircular groove 50 ;

[0027] Figure 6 shows a cross section of a part of a pressure sensor 1 according to the invention, comprising a sensor unit 10 , a housing 20 , a sleeve 30 and a sealing element 40 in a semicircular groove 50 ;

[0028] Figure 7 It is shown that according to the present invention Figures 1 to 6 A cross section of a sensor unit 10 of the pressure sensor 1 is shown;

[0029] Figure 8 It is shown that according to the present invention Figures 1 to 6 An exploded view of some components of the pressure sensor 1 is shown, including a sensor unit 10, a housing 20, a sleeve 30 and a sealing element 40;

[0030] Fig. 9 The manufacturing method according to the present invention is shown as follows Figures 1 to 6 A view of a first step of the method showing a pressure sensor 1 , wherein a housing 20 is placed on a sensor unit 10 ;

[0031] Fig.10 The manufacturing method according to the present invention is shown as follows Fig. 9 A view of the second step of the method showing pressure sensor 1 , in which sealing element 40 is placed on housing 20 ; and

[0032] Fig.11 The manufacturing method according to the present invention is shown as follows Fig.10 The illustration shows a third step of the method for producing pressure sensor 1 , in which sleeve 30 is placed on sealing element 40 and housing 20 .

[0033] The same reference numerals refer to the same objects in the drawings.

[0034] The reference numerals are listed as follows:

[0035] 1Pressure sensor

[0036] 11 plunger unit

[0037] 11.1 Distal plunger end

[0038] 11.11 Pressure receiving surface

[0039] 11.2 Proximal plunger end

[0040] 11.3 Preload sleeve

[0041] 11.4 Preload sleeve space

[0042] 11.5 Preload

[0043] 12 measuring elements

[0044] 14 socket unit

[0045] 10 sensor units

[0046] 13 Electrode assembly

[0047] 15 socket contacts

[0048] 16 Insulator

[0049] 20 Shell

[0050] 20.1 Distal housing end

[0051] 20.2 Proximal housing end

[0052] 20.3 Shell cavity

[0053] 20.4 Shell opening

[0054] 20.5 Shell-Preload Body-Connection

[0055] 30 sleeve

[0056] 30.1 Distal sleeve end

[0057] 30.2 Proximal sleeve end

[0058] 30.3 Sleeve-housing-connection

[0059] 30.4 Clearance

[0060] 40 Sealing element

[0061] 40.1 Torus seal

[0062] 40.2 Torus-shaped opening

[0063] 50 grooves

[0064] 50.1 First groove wall

[0065] 50.2 Second groove wall

[0066] 50.3 Third groove wall

[0067] A longitudinal axis

[0068] B Pressure receiving surface

[0069] C Pressure Chamber

[0070] H hole

[0071] M Medium

[0072] P Pressure

[0073] S Measurement signal

[0074] T Temperature

[0075] W Wall DETAILED DESCRIPTION

[0076] Figures 1 to 6 Cross-sections of various embodiments of a part of a pressure sensor 1 according to the invention are shown. 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 mold, an internal combustion engine, etc. In an injection mold, the medium M is a liquid melt of plastic, metal, etc. In an internal combustion engine, the medium M is a fuel-air mixture. The medium M can have a temperature T of several hundred degrees Celsius and a pressure P of 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 50 bar to 5000 bar. The pressure P to be measured is Figures 1 to 6 It is schematically indicated by a black arrow.

[0077] The pressure sensor 1 has a sensor unit 10. The sensor unit 10 has the function of accommodating a measuring element 12. The sensor unit 10 is Figures 1 to 6 is only partially shown in Figure 7 The cross-sectional view and Figure 8 The sensor unit 10 is shown in its entirety in the exploded view of FIG.

[0078] Pressure sensor 1 has a longitudinal axis A. Figures 1 to 8 Pressure sensor 1 is shown along a longitudinal axis A.

[0079] The pressure sensor 1 has a housing 20. The housing 20 has the function of fastening the sensor unit 10 in the hole H of the wall W of the pressure chamber C. The fastening of the pressure sensor 1 in the hole H via the housing 20 may be a threaded connection. This threaded connection is not shown in the figure.

[0080] In the illustrated embodiment, the housing 20 is hollow cylindrical and is made of a mechanically resistant material, such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. Figure 8 As shown, the housing 20 has a distal housing end 20.1 and a proximal housing end 20.2, wherein the distal housing end 20.1 is arranged farther from the measuring element 12 than the proximal housing end 20.2 on the longitudinal axis A. The housing 20 has a housing inner cavity 20.3. The housing 20 radially surrounds the housing inner cavity 20.3 with respect to the longitudinal axis A. The sensor unit 10 is arranged in the housing inner cavity 20.3.

[0081] In addition to the measuring element 12 , the sensor unit 10 also has a plunger unit 11 .

[0082] The plunger unit 11 has a first function of receiving the pressure P to be measured and transmitting it to the measuring element 12. To this end, the plunger unit 11 has a distal plunger end 11.1, a proximal plunger end 11.2 and a preload sleeve 11. The plunger unit 11 is made of a mechanically resistant material, such as a pure metal, a nickel alloy, a cobalt alloy, an iron alloy, etc. In the illustrated embodiment, the distal plunger end 11.1, the proximal plunger end 11.2 and the preload sleeve 11.3 are integral. Here, the distal plunger end 11.1 and the proximal plunger end 11.2 are cylindrical and blend into each other. The proximal plunger end 11.2 blends into the preload sleeve 11.3. The preload sleeve 11.3 is hollow cylindrical and surrounds a preload sleeve space 11.4. The measuring element 12 is arranged in the preload sleeve space 11.4. The distal plunger end 11.1 is arranged farther from the measuring element 12 on the longitudinal axis A than the proximal plunger end 11.2. The distal plunger end 11.1 has an end surface at its end, which is also referred to as a pressure receiving surface 11.11. The pressure P to be measured acts on the distal plunger end 11.1 through the pressure receiving surface 11.11 and is transferred from the distal plunger end 11.1 to the proximal plunger end 11.2. Subsequently, the pressure P to be measured acts directly on the measuring element 12 from the proximal plunger end 11.2.

[0083] Another function of the plunger unit 11 is to prevent mechanical stresses originating from the hole H in the wall W of the pressure chamber C in which the pressure sensor 1 is fastened, from reaching the measuring element 12 from the housing 20, since such mechanical stresses could distort the measurement of the pressure P. To this end, the plunger unit 11 has a preload body 11.5. In the illustrated embodiment, the preload body 11.5 is hollow cylindrical. 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. By such fastening, the measuring element 12 is mechanically preloaded and arranged between the proximal plunger end 11.2 and the preload body 11.5 along the longitudinal axis A. The term "mechanical preload" refers to the mechanical preload formed before the actual measurement of the pressure P. Preferably, the value of the mechanical preload is at least one decimal order of magnitude greater than the possible mechanical stress of the pressure sensor 1 fastened in the wall W of the pressure chamber C via the housing 20 (decimal order of magnitude). ).

[0084] The preload sleeve 11.3 is thin-walled, having a wall thickness less than / equal to 0.1 mm. The thin-walled preload sleeve 11.3 allows the plunger 11 to have greater mobility and thus makes the pressure sensor 1 highly sensitive. The medium M with high temperature T and high pressure P must be prevented from penetrating into the housing cavity 20.3 through the gap 30.4. In the injection mold, the medium M is a liquid melt, which hardens in the housing cavity 20.3 and thus can prevent the movement of the plunger 11. In an internal combustion engine, the medium M is a fuel-air mixture, which is chemically corrosive and can corrode the preload sleeve 11.3 in the housing cavity 20.3 and thus damage or destroy it.

[0085] The measuring element 12 has the function of generating a measuring signal S for the pressure P to be measured. The measuring element 12 can be a piezoelectric measuring element, a piezoresistive measuring element, a strain gauge, etc. The size of the measuring signal S is proportional to the measuring pressure P.

[0086] The sensor unit 10 furthermore has an electrode assembly 13 , a socket unit 14 , socket contacts 15 and an insulator 16 .

[0087] The socket unit 14 has the function of accommodating the electrode assembly 13, the socket contact 15 and the insulator 16. To this end, the socket unit 14 has a hollow cylindrical socket housing, which is made of a mechanically resistant material, such as pure metal, nickel alloy, cobalt alloy, iron alloy, etc. The socket housing is fastened to the pretensioning body 11.5 on the side of the pretensioning body 11.5 facing away from the measuring element 12 by means of a socket housing-pretensioning body-connection portion. The socket unit 14 has a socket space inside the socket housing. The electrode assembly 13, the socket contact 15 and the insulator 16 are arranged in the socket space.

[0088] The electrode assembly 13 has the function of conducting the measurement signal S from the measuring element 12 to the socket contact 15. In the illustrated embodiment of the sensor unit 10, the electrode assembly 13 is cylindrical and made of a conductive material, such as copper, silver, gold, etc. The electrode assembly 13 is arranged at the end of the socket unit 14 facing the measuring element 12 and extends from the socket space into the preload sleeve space 11.4. The electrode assembly 13 is electrically connected to the measuring element 12. The electrode assembly 13 conducts the measurement signal S from the measuring element 12 along the longitudinal axis A to the socket contact 15.

[0089] The socket contact 15 has the function of providing a measurement signal S to the outside of the socket unit 14. In the illustrated embodiment, the socket contact 15 is cylindrical and made of a conductive material such as copper, silver, gold, etc. The socket contact 15 is arranged at the end of the socket unit 14 facing away from the measuring element 12. The electrode assembly 13 and the socket contact 15 are electrically connected to each other.

[0090] The insulator 16 has the function of electrically insulating the electrode assembly 13 and the socket contact 15 from the socket housing. The insulator 16 is hollow cylindrical and is made of an electrically insulating and mechanically rigid material, such as ceramic, Al2O3 ceramic, sapphire, etc. The insulator 16 is radially arranged outside the electrode assembly 13 and the socket contact 15 with respect to the longitudinal axis A.

[0091] The plunger unit 11 and the measuring element 12 are thus arranged as components of the sensor unit 10 in the housing interior 20.3. The distal plunger end 11.1 protrudes from the housing 20. Figure 1 The distal housing end 20.1 has a housing opening 20.4. The distal plunger end 11.1 extends all the way to the pressure chamber C through the housing opening 20.4.

[0092] According to the invention, the pressure sensor 1 has a sleeve 30. The sleeve 30 has the function of accommodating at least one sealing element 40. The sleeve 30 is hollow cylindrical 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 has a distal sleeve end 30.1 and a proximal sleeve end 30.2, and the distal sleeve end 30.1 is arranged farther from the measuring element 12 along the longitudinal axis A than the proximal sleeve end 30.2.

[0093] Preferably, the distal plunger end 11.1 projects as far as the distal sleeve end 30.1. The pressure receiving surface 11.11 and the distal sleeve end 30.1 are located in a pressure receiving plane B perpendicular to the longitudinal axis A. This has the advantage that the pressure P can only act on the distal plunger end 11.1 via the pressure receiving surface 11.11 parallel to the longitudinal axis A. This prevents pressure components that do not act parallel to the longitudinal axis A from acting on the distal plunger end 11.1, which could distort the measurement of the pressure P if the measuring element 12 generates interference signals for pressure components that do not act parallel to the longitudinal axis A. Avoiding such pressure components that do not act parallel to the longitudinal axis A increases the sensitivity and accuracy of the pressure P measurement. Alternatively, there is also the advantage that the distal plunger end 11.1 can be matched to the distal sleeve end 30.1 by targeted cutting of the surface geometry of the wall W of the pressure chamber C. The distal plunger end 11 . 1 and the distal sleeve end 30 . 1 can therefore be cut in accordance with the surface geometry of the wall W of the pressure chamber C which runs obliquely or curved relative to the longitudinal axis A.

[0094] The sleeve 30 is fastened to the housing 20. Preferably, the sleeve 30 is connected at the proximal sleeve end 30.2 by a sleeve-housing connection (Hülse- The sleeve-housing connection 30.3 is fastened to the distal housing end 20.1. The sleeve-housing connection 30.3 is arranged radially outwardly on the proximal sleeve end 30.2 and the distal housing end 20.1 with respect to the longitudinal axis A. The sleeve-housing connection 30.3 is welded, soldered, or welded to the distal housing end 20.1. The sleeve-housing connection 30 . 3 is a welded connection.

[0095] The sleeve 30 partially surrounds the distal plunger end 11.1. The sleeve 30 surrounds the distal plunger end 11.1 radially outwardly with respect to the longitudinal axis A. The distal plunger end 11.1 has a side surface Preferably, the sleeve 30 surrounds the side surface of the distal plunger end 11 . 1 by 360° on the radial outside.

[0096] The sleeve 30 and the distal plunger end 11.1 are spaced apart from each other by a gap 30.4. Preferably, the gap 30.4 has a width in a radial direction perpendicular to the longitudinal axis A of less than / equal to 0.1 mm.

[0097] The sleeve 30 and the housing 20 form at least one groove 50. The groove 50 is used to accommodate the sealing element 40. Preferably, the groove 50 is arranged in the region of the proximal sleeve end 30.2 and the distal housing end 20.1. The sealing element 40 is arranged in the groove 50.

[0098] The sleeve 30 can have a length of several centimeters along the longitudinal axis A. Accordingly, the groove 50 and the sealing element 40 are located 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 with a high temperature T, the sealing element 40 is not exposed to the high temperature T of the medium M during operation of the pressure sensor 1, because the temperature T in the wall W and therefore in the sleeve 30 decreases with increasing distance from the pressure chamber C.

[0099] However, the sleeve 30 can also have a length of only a few millimeters along the longitudinal axis A. Accordingly, the groove 50 and the sealing element 40 are located at a relatively small distance of a few millimeters from the pressure chamber C. This has the advantage that the medium M with low viscosity cannot penetrate deep into the gap 30.4 along the longitudinal axis A before it impinges on the sealing element 40.

[0100] The groove 50 is arranged radially inside the sleeve 30 and the housing 20 with respect to the longitudinal axis A. The groove 50 is annular. The groove 50 has 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.

[0101] In accordance with Figure 1 In an embodiment of the pressure sensor 1, the cross section of the groove 50 is rectangular and has three groove walls 50.1, 50.2, 50.3. Among 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 and the third groove wall 50.3 are straight and arranged at 90° relative to the longitudinal axis A, and the second groove wall 50.2 is straight and arranged parallel to the longitudinal axis A.

[0102] In accordance with Figure 2 In an embodiment of the pressure sensor 1, the cross section of the groove 50 is triangular and has 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 and the second groove wall 50.2 are arranged obliquely relative 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° relative to the longitudinal axis A. The two inclined groove walls 50.1, 50.2 allow the sealing element 40 to be accurately positioned in the groove 50.

[0103] In accordance with Figure 3 In an embodiment of the pressure sensor 1, the cross section of the groove 50 is trapezoidal and has three groove walls 50.1, 50.2, 50.3. Among 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 and the third groove wall 50.3 are arranged obliquely relative to the longitudinal axis A, and the second groove wall 50.2 is straight and arranged 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° relative to the longitudinal axis A.

[0104] In accordance with Figure 4In an embodiment of the pressure sensor 1, the cross-section of the groove is circular and has 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 circular and bulges from the longitudinal axis A into the proximal sleeve end 30.2. Preferably, the bulge has a constant radius. The second groove wall 50.2 is circular and bulges from the longitudinal axis A into the distal housing end 20.1. Preferably, the bulge has a constant radius. The two circular groove walls 50.1, 50.2 allow the sealing element 40 to be precisely positioned in the groove 50.

[0105] In accordance with Figure 5 In an embodiment of the pressure sensor 1, the groove is semicircular and has three groove walls 50.1, 50.2, 50.3. Among 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 circular and bulges from the longitudinal axis A to the proximal sleeve end 30.2. Preferably, the bulge has a constant radius. The second groove wall 50.2 is straight and arranged parallel to the longitudinal axis A. The third groove wall 50.3 is straight and arranged at a 90° angle relative to the longitudinal axis A.

[0106] In accordance with Figure 6 In an embodiment of the pressure sensor 1, the groove is semicircular and has three groove walls 50.1, 50.2, 50.3. Among 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 arranged at a 90° angle relative to the longitudinal axis A. The second groove wall 50.2 is straight and arranged parallel to the longitudinal axis A. The third groove wall 50.3 is round and bulges from the longitudinal axis A into the distal housing end 20.1. Preferably, the bulge has a constant radius.

[0107] On the basis of understanding the present invention, those skilled in the art can also Figures 1 to 6 The six embodiments of the grooves shown can be combined with one another.

[0108] According to the invention, the pressure sensor 1 has at least one sealing element 40. The sealing element 40 has the function of sealing the gap 30.4. In the sense of the invention, the verb "seal" means that during operation of the pressure sensor 1, no medium M can enter the housing interior 20.3 through the gap 30.4. Preferably, the sealing element 40 permanently seals the gap 30.4 at a temperature of 100° C. to 500° C. and a pressure P of 50 bar to 5000 bar. The sealing element 40 is toroidal and consists of an elastic sealing material, such as an elastomer, in particular a fluoroelastomer or a perfluoroelastomer, or a rubber, in particular acrylonitrile-butadiene rubber, etc.

[0109] In the illustrated embodiment, the sealing element 40 has a torus-shaped sealing body 40.1 and a torus-shaped opening 40.2. The torus-shaped sealing body 40.1 surrounds the torus-shaped opening 40.2. The distal plunger end 11.1 protrudes through the torus-shaped opening 40.2.

[0110] The sealing element 40 is arranged in the groove 50. The sealing element 40 seals the gap 30.4 by sealing extrusion. This sealing extrusion can be implemented as axial sealing extrusion along the longitudinal axis A, or radial sealing extrusion perpendicular to the longitudinal axis A, or a combination of axial sealing extrusion along the longitudinal axis A and radial sealing extrusion perpendicular to the longitudinal axis A. The sealing element 40 is arranged in the groove 50 by pre-extrusion. The pre-extrusion is applied to the sealing element 40 by the groove walls 50.1, 50.2, 50.3. In addition to the pre-extrusion, the pressure P in the gap 30.4 also acts on the sealing element 40 as pressure extrusion. Therefore, the sealing extrusion is formed by the pre-extrusion and the pressure extrusion.

[0111] After understanding the present invention, a person skilled in the art can arrange multiple sealing elements in one groove or multiple grooves. The multiple sealing elements are arranged in sequence about the longitudinal axis A, thereby sealing the gap 30.4 multiple times.

[0112] Figures 9 to 11 Three steps of the method for producing a pressure sensor 1 according to the invention are shown in diagrammatic form. Figures 9 to 11 Pressure sensor 1 is also shown along its longitudinal axis A.

[0113] In such Fig. 9In the first step of the method according to the invention shown, a housing 20 and a sensor unit 10 are provided, and the housing 20 is pushed onto the plunger unit 11 along the longitudinal axis A and placed on the sensor unit 10. As a result, the plunger unit 11 extends into the housing inner cavity 20.3. The distal plunger end 11.1 thereby extends through the housing opening 20.4. The proximal housing end 20.2 is placed on the pretensioner 11.5. The housing 20 thus placed on the pretensioner 11.5 is fastened to the pretensioner 11.5 via a housing-pretensioner connection 20.5. The housing-pretensioner connection 20.5 is arranged on the housing 20 and the pretensioner 11.5 radially on the outside with respect to the longitudinal axis A. In the illustrated embodiment, the housing-pretensioner connection 20.5 is a welded connection.

[0114] In such Fig.10 In the second step of the method according to the invention shown, the sealing element 40 is provided and pushed along the longitudinal axis A onto the distal plunger end 11.1 and then placed on the housing 20. The distal plunger end 11.1 thereby projects out of the torus-shaped opening 40.2.

[0115] In such Fig.11 In the third step of the method according to the invention shown, a sleeve 30 is provided and pushed along the longitudinal axis A onto the distal plunger end 11.1 and placed onto the sealing element 40 and the housing 20. The proximal sleeve end 30.2 lies on the distal housing end 20.1. The sleeve 30 thus placed on the housing 20 is fastened to the housing 20 via the sleeve-housing connection 30.3. The sealing element 40 is pre-compressed by the placed sleeve 30 and the housing 20.

Claims

1. A pressure sensor (1), comprising a housing (20), a plunger unit (11) and a measuring element (12); the housing (20) having a housing inner cavity (20.3), and the plunger unit (11) and the measuring element (12) being arranged in the housing inner cavity (20.3); the plunger unit (11) having a distal plunger end (11.1) and a proximal plunger end (11.2), the distal plunger end (11.1) being arranged to be farther from the measuring element (12) than the proximal plunger end (11.2) on the longitudinal axis (A) of the pressure sensor (1), and the distal plunger end (11.1) protruding from the housing (20), and the proximal plunger end (11.2) being in effective connection with the measuring element (12) and transmitting the pressure (P) of a medium (M) outside the housing (20) to the measuring element (12); It is characterized in that The pressure sensor (1) has a sleeve (30), and 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); as well as The pressure sensor (1) has at least one sealing element (40) which seals the gap (30.4) by sealing compression to prevent the medium (M) from passing into the housing interior (20.3).

2. The pressure sensor (1) according to claim 1, characterized in that The sealing element (40) is toroidal and consists of an elastic sealing material, such as an elastomer, in particular a fluoroelastomer or a perfluoroelastomer, or a 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 sealing body (40.1) and a toroidal opening (40.2), wherein the toroidal sealing body (40.1) surrounds the toroidal opening (40.2); and the distal plunger end (11.1) protrudes through 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 inside 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) has a plurality of groove walls (50.1, 50.2, 50.3); the groove walls (50.1, 50.2, 50.3) pre-extrude a sealing element (40) arranged in the groove (50); and the pressure (P) in the gap (30.4) acts on the sealing element (40) as a pressure extrusion in addition to the pre-extrusion, and the pre-extrusion and the pressure extrusion form a sealing extrusion.

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), wherein the distal housing end (20.1) is arranged to be farther 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), wherein the distal sleeve end (30.1) is arranged to be farther 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 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) has a plurality of groove walls (50.1, 50.2, 50.3), wherein at least one groove wall (50.1, 50.2) is part of the proximal sleeve end (30.2) and wherein at least one groove wall (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 cross section of the groove (50) is rectangular, triangular, trapezoidal, circular, or semicircular.

9. The pressure sensor (1) according to any one of claims 1 to 8, characterized in that The plunger unit (11) comprises a preload sleeve (11.3) and a preload body (11.5); the proximal plunger end (11.2) is integrated into the preload sleeve (11.3); the preload sleeve (11.3) surrounds a preload sleeve space (11.4), and the measuring element (12) is arranged in the preload sleeve space (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 wherein the measuring element (12) is arranged between the proximal plunger end (11.2) and the preload body (11.5) along the longitudinal axis (A) under mechanical preload.

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

11. A method for manufacturing a pressure sensor (1), the pressure sensor comprising a housing (20), a plunger unit (11) and a measuring element (12); the housing (20) comprising a housing inner cavity (20.3), and the plunger unit (11) and the measuring element (12) are arranged in the housing inner cavity (20.3); the plunger unit (11) comprising a distal plunger end (11.1) and a proximal plunger end (11.2), the distal plunger end (11.1) is arranged farther from the measuring element (12) on the longitudinal axis (A) of the pressure sensor (1) than the proximal plunger end (11.2), and the distal plunger end (11.1) protrudes from the housing (20), and the proximal plunger end (11.2) is in effective connection with the measuring element (12) and transmits the pressure (P) of the medium (M) existing outside the housing (20) to the measuring element (12); It is characterized in that In a first step of the method, the housing (20) and the sensor unit (10) having a plunger unit (11) and a measuring element (12) are provided, and the housing (20) is pushed onto the plunger unit (11) along the longitudinal axis (A) and placed on the sensor unit (10); In a second step of the method, at least one sealing element (40) is provided and pushed along the longitudinal axis (A) onto the distal plunger end (11.1) and placed on the housing (20); as well as In the third step of the method, a sleeve (30) is provided and pushed onto the distal plunger end (11.1) along the longitudinal axis (A) and placed on the sealing element (40) and the housing (20), the sleeve (30) and the distal plunger end (11.1) being separated from each other by a gap (30.4), and the sealing element (40) sealing the gap (30.4) by sealing extrusion to prevent the medium (M) from entering the housing cavity (20.3).

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

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

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

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

Images