Device for reducing pressure pulses in pressure sensors

Abstract

Device for damping pressure pulses in a pressure sensor (10) with a housing (14), wherein a damping insert (34) is received in a pressure channel (20), the damping insert (34) being substantially cylindrical and having a first flat side (56) on an upstream side of the damping insert (34), a second flat side (58) on an downstream side of the damping insert (34), and a lateral surface (52), wherein the damping insert (34) has a single circumferential damping channel (54) approximately in the middle, with respect to its axial length, wherein the damping channel (54) is provided as a circumferential groove in the lateral surface (52) and has a rectangular or square flow cross-section, wherein circumferential openings (60) provided in the lateral surface (52) and connected to the damping channel (54) open onto the first flat side (56) and the second flat side (58).wherein the circumferential openings (60) are provided in a 90° orientation and wherein the circumferential openings (60) that open onto the second plan side (58) of the damping insert (34) are arranged offset by approximately 90° with respect to the circumferential openings (60) that open onto the first plan side (56) of the damping insert (34).

Description

State of the art

[0001] DE 33 06 711 C1 relates to a device for damping short-term pressure fluctuations in gaseous media. It is proposed to provide a first compensating chamber with a throttling point at its end along the supply lines to a differential pressure gauge, with this end projecting into a second compensating chamber with a significantly larger volume.

[0002] DE 698 15 801 T2 relates to a pressure transducer. The pressure transducer comprises a connector with a pressure inlet opening. Furthermore, the pressure transducer includes a pressure sensing component attached to one end of the pressure inlet opening and an output device electrically connected to the pressure sensing component. The output device has a circuit carrier substrate spaced apart from the pressure sensing component. A base element is mounted around the pressure sensing component and attached to the connector. A connection is attached to the base element, the connection having an elastically deformable section between the first and second ends.

[0003] DE 90 17 855 U1 relates to an overload protection device for pressure sensors. The device for protecting a pressure sensor immersed in a liquid, in particular a piezoresistive pressure sensor, against short-term overpressure loads comprises a measuring pressure inlet of the pressure sensor, to the free end of which an open capillary is connected. The capillary is made of a dimensionally stable material such as metal, Plexiglas, polyamide, or the like and is filled with gas or air. The capillary consists of an elastic material, with its outer wall being shielded from the ambient pressure. The capillary is wound into a spiral or helical shape. The spiral or helical shape can be subdivided into several, for example, three-part spirals or three-part helixes, which are arranged with their angular axes at angles to each other, preferably at right angles to each other.

[0004] Pressure sensors used today experience pressure spikes at the sensor due to hydraulic vibrations, which in extreme cases can even destroy it. One way to prevent this is to install a damping element or a restrictor to reduce the cross-section. The cross-section must be adapted to the specific requirements. However, this is partly limited by technical constraints, and furthermore, reducing the cross-section may affect the interface geometry during the connection process.

[0005] From DE 10 2004 002 089 A1, a device for damping pressure pulses in a pressure sensor with a housing is known, wherein a damping insert is received in a pressure channel, the damping insert having a first flat surface on an upstream side of the damping insert, a second flat surface on an downstream side of the damping insert, and a lateral surface, wherein at least one damping channel designed as a circumferential groove extends along the lateral surface, wherein circumferential openings, introduced into the lateral surface and connected to the at least one damping channel, open into the lateral surface at the first and second flat surfaces. The circumferential openings extend in their axial direction beyond the damping channel in a straight line from the first flat surface to the second flat surface.

[0006] Another device, a device for damping pressure pulses, is known from US 5 343 754 A. Description of the invention

[0007] According to the invention, a device for damping pressure pulses in a pressure sensor with a housing is proposed, wherein a damping insert is received in a pressure channel, the damping insert being essentially cylindrical and having a first flat side on an upstream side of the damping insert, a second flat side on an downstream side of the damping insert, and a lateral surface, wherein the damping insert has a single circumferential damping channel approximately centrally, with respect to its axial length, wherein the damping channel is formed as a circumferential groove in the lateral surface and has a rectangular or square flow cross-section, wherein circumferential openings are provided in the lateral surface on the first flat side and on the second flat side and are connected to the damping channel, wherein the circumferential openings are provided in a 90° orientation and wherein the circumferential openings,The openings on the second flat side of the damping insert are arranged approximately 90° offset from the openings on the first flat side. Advantageously, the damping insert is integrated into a channel, such as the pressure channel of a pressure sensor. This simplifies manufacturing and achieves improved damping of pressure pulses and a reduction of pressure peaks. By using a damping insert with at least one damping channel, the technical problem of limited manufacturability and the impact on the interface geometry and the connection process can be mitigated.

[0008] The geometric design of the damping insert significantly extends the path of the pressure pulse. For example, the damping channel on the damping insert can extend along its circumferential surface in a thread-like fashion, thereby considerably increasing the length of the damping channel – in this case, running circumferentially. The damping insert, with its damping channel on its circumferential surface, is installed in the pressure sensor housing in such a way that the damping channel on the circumferential surface of the damping insert is covered, i.e., sealed, by the housing wall of the pressure sensor housing.Due to the increased wall friction to which a pressure pulse passing through the damping channel is subjected, as well as any interference that occurs, pressure peaks that ultimately reach the sensor element can no longer damage it, since the pressure energy is significantly reduced during its passage through the at least one damping channel along the circumferential surface of the damping insert. The geometric shape of the damping channel can be optimally designed for the manufacture of the damping insert.

[0009] The damping insert proposed according to the invention can be installed in the pressure port of a pressure sensor, in particular in its pressure channel. Alternatively, the damping insert can also be installed in a channel parallel to the pressure channel within the housing of the pressure sensor. The pressure sensor can have a threaded connection or be attached to a flanged connection. The damping insert proposed according to the invention can be fastened in the pressure channel of the pressure sensor mechanically, for example by crimping, or thermally, for example by means of a material-bonded joining process such as welding.

[0010] The damping capacity of the damping insert proposed according to the invention, e.g., in the pressure channel of the housing of the pressure sensor-integrated damping element, is determined in particular by the length of the damping channel on the outer surface of the damping element. The longer the circumferential length of the damping channel, the greater the damping of the pressure pulse passing through this damping channel. Advantageously, the damping capacity of the damping insert proposed according to the invention is influenced by several openings distributed around the circumference, resulting in a relatively low risk of clogging by particles contained in the gaseous medium.Furthermore, the damping insert proposed according to the invention makes it possible to achieve an overlap of the travel paths of the pressure pulses with a mutual cancellation of the pressure pulses within the damping channel, and, due to the length of the at least one damping channel in the circumferential direction on the outer surface of the damping insert, a significant delay of the pressure pulse can be achieved. Brief description of the drawing

[0011] The invention is described in more detail below with reference to the drawing:

[0012] It shows: Fig. 1 a sensor, in particular a pressure sensor with flange connection, Fig. 2. The schematic representation of a sensor, in particular a pressure sensor with threaded connection, Fig. 3 a perspective view of the pressure sensor with flange connection, Fig. 4 A perspective view of the pressure sensor with threaded connection Fig. 5 the damping insert in the state installed in the pressure channel, Fig. 6 a variant of the damping insert. Design variants

[0013] According to the representation Fig. Figure 1 shows a sensor, in particular a pressure sensor 10, the housing 14 of which is attached to a flange 12. The sensor, in particular designed as a pressure sensor 10, extends vertically downwards along a flat side of the flange 12. The pressure sensor 10 comprises the housing 14, through which a pressure channel 20 extends. From the illustration according to Fig. Figure 1 further shows that the housing 12 of the pressure sensor 10 is sealed against the flange 12 by means of a sealing element 22. The housing 14 comprises a Fig. 1. Thread (not shown) through which the housing 14 of the pressure sensor 10 is fastened to the flange 12. When the housing 14 of the pressure sensor 10 is fastened, the upper annular surface of a collar 18, which is formed on the housing 14, rests against a lower flat surface of the flange 12 and compresses the sealing element 22, which is embedded in a corresponding recess in the housing 14 of the pressure sensor 10. Fig. Figure 1 further shows that the pressure channel 20 extends through the housing 14 of the pressure sensor 10, in which a throttle insert 24 is formed. The throttle insert 24 comprises a throttle point 28 and a cross-sectional expansion 26 directed towards the pressure channel 20. On the upstream side of the throttle insert 24, upstream of the throttle point 28, a bulge 30 is recessed into the throttle insert 24; the throttle point 28 adjoins this bulge immediately.

[0014] The housing 14 of the pressure sensor 10 further comprises a rib 16, the rib 16 having several individual ribs oriented circumferentially at 90° to each other. The rib 16 stiffens the extension of the pressure sensor 10, which extends essentially vertically downwards, through which the pressure channel 20 passes. Fig. 1 not shown - extends to the rounded tip.

[0015] Fig. Figure 2 shows a sensor, in particular a pressure sensor with a threaded connection.

[0016] According to the sectional view Fig. Figure 2 shows that the housing 14 of the pressure sensor 10 has several threads of a thread 32 on its outer surface. A cone 42 for sealing a [missing information] is located on the underside of the housing 14. Fig. 2. The conical seat (not shown) is formed when screwing the housing 14 into a similar one. The housing 14 encompasses the pressure channel 20 and is symmetrical about an axis 38. In the area of ​​the cone 42, there is an opening 40 of the pressure channel 20. From the illustration according to Fig. Figure 2 shows that the throttle insert 24 is installed in the area of ​​the opening 40 of the pressure channel 20. The throttle insert 24 has a substantially pot-shaped appearance, with an opening 36 formed in the bottom of the pot-shaped throttle insert 24.

[0017] The difference between the variants according to Fig. 1 and Fig. 2 lies in the fact that in the execution variant according to Fig. 2 the pressure channel 20 runs centrally in the housing 14 of the pressure sensor 10, while the pressure channel 20 in the embodiment according to Fig. 1 is formed off-center in the housing 14.

[0018] Fig. Figure 3 shows a perspective view of the pressure sensor with flange view.

[0019] From the representation according to Fig. Figure 3 shows that the pressure sensor 10 projects essentially vertically downwards from the lower flat surface of the flange 12. Mounting openings 46 are located in the flange 12; furthermore, a connector opening for electrical contacting the pressure sensor 10 extends above the flange 12 on the underside of the flange 12. The extension, which is stiffened on its outer surface by the ribbing 16, extends in the area shown here according to the illustration. Fig. Three dashed lines represent the pressure channel 20, which opens at an opening 40 in the tip of the extension of the pressure sensor 10. The ribbing 16 ends below the collar 18, with which the housing 14 of the pressure sensor 10 is screwed into the flange 12. Above the collar 18, the sealing element 22 is received in a corresponding recess on the circumferential surface 14.

[0020] From the representation according to Fig. Figure 4 shows a perspective view of the pressure sensor with threaded connection according to Fig. 2 stands out.

[0021] Below a tool projection 48 extends the housing 14 of the pressure sensor 10, which in this embodiment is provided with a thread 32 having several threads on its outer surface. Below the thread runout of the thread 32, a rounded seating surface can be provided on the housing 14 as shown in Fig. 4 may be formed, or also a cone 42 as shown in the illustration according to Fig. 2 is depicted as being designed in a conical seat geometry with complementary geometry. As shown Fig. As shown in section 4, the pressure channel 20 extends centrally through the housing 14, terminating in the opening 40 at the top of the housing 14. Above the tool projection 48 for generating a screw-in torque, a collar 50 extends, above which a connector is provided for electrical contacting the pressure sensor 10.

[0022] According to the representation Fig. 5 the damping insert proposed according to the invention is to be removed in the state installed in the pressure channel, wherein the pressure channel 20 runs off-center in the housing 14.

[0023] The representation according to Fig. Figure 5 shows an enlarged section of the perspective drawing according to Fig. 3 dar.

[0024] A pressure pulse entering the pressure channel 20 through the opening 40 at the tip of the extension of the pressure sensor 10 passes through the pressure channel 20 before exiting as shown in the illustration. Fig. 5 on a first plan side 56 of a damping insert 34 embedded in the pressure channel 20. Preferably, the damping insert 34 is mechanically fastened in the pressure channel 20, e.g. by hot riveting or by means of a material-bonded joining process, such as welding. As shown in the illustration according to Fig. As can be seen from Figure 5, the damping insert 34 comprises a lateral surface 52. Circumferential openings 60 are provided in the lateral surface 52. The circumferential openings 60 are in the embodiment according to Fig. 5 in a 90° orientation. Instead of the in Fig. In Figure 5, the four circumferential openings 60 shown, which are arranged at a 90° offset from each other, could also be provided with only two or three circumferential openings 60. The damping insert 34 has a circumferential damping channel 54 approximately in the middle, viewed with respect to its axial length. The damping channel 54 is bounded by a section of the damping insert 34 in whose lateral surface 52 a number of circumferential openings 60 are also formed. These circumferential openings 60 are formed at an offset 62 with respect to the aforementioned circumferential openings 60. In the embodiment according to Figure 5, the circumferential openings 60 are arranged in a 90° offset from the first circumferential openings 60. Fig. The damping insert 34 has a single damping channel 54, formed as a circumferential groove, through which the path of a pressure pulse is extended. On the downstream side, i.e., in the region of a second flat surface 58 of the essentially cylindrical damping insert 34, the gaseous medium flows into the pressure channel 20 and, with reduced momentum, towards the sensor element located at the end of the pressure channel 20.

[0025] The one shown in the illustration according to Fig. The damping channel 54, which is centrally embedded in the outer surface 52 of the damping insert 34, is bounded on one side by the outer surface 52 of the damping insert 34 and on the other side by the wall of the pressure channel 20. The damping insert 34 increases the wall friction of the gaseous medium as it flows through the at least one damping channel 54 formed in the outer surface 52 of the damping insert 34. The greater the path length of the pressure pulse through the damping channel 54, the greater the reduction of the pressure pulse's momentum. This drastically minimizes the pressure peaks that ultimately impact the sensor element located at the end of the pressure channel 20, preventing damage to the sensor element.The number of circumferential openings 60 on the outer surface 52 of the damping insert 34 proposed according to the invention advantageously prevents the risk of clogging by particles contained in the gaseous medium that adhere to the circumferential openings 60. The solution proposed according to the invention, namely the insertion of a damping insert 34 into the pressure channel 20, allows the resulting damping effect to be optimized depending on the design of the pressure pulse path through the damping channel 54 and the area downstream of the damping insert 34, i.e., on the second face 58 of the damping insert.

[0026] For the sake of completeness, it should be mentioned that the in Fig. 5 dashed lines representing pressure channel 20 - as in connection with Fig. As already mentioned, the pressure sensor 10 is fed through the opening 40 at its tip via the pressure channel 20. Depending on the position of the damping insert 34 within the axial length of the pressure channel 20, the buffer volume present downstream of the second face 58 of the damping insert 34 can be used for further damping of the pressure pulse.

[0027] In the representation according to Fig. Figure 6 shows the damping insert individually.

[0028] As already mentioned above in connection with Fig. As explained in section 5, the damping insert 34 is limited by a first plan page 56 and a second plan page 58. In the Fig. 6 shown design variant, which corresponds to the design variant in the installed state according to Fig. In accordance with section 5, a single damping channel 54 is embedded in the outer surface 52 of the essentially cylindrical damping element 34. This channel extends the path 66 of a pressure pulse entering the outer surface 52 at the first face 56 via circumferential openings 60. The circumferential extension of the path 66 achieved via the damping channel 54 significantly increases wall friction, resulting in pressure peaks as the pulse passes through the damping channel 54, which is formed as a circumferential groove in the outer surface 52 of the damping element 34. On the outflow side, i.e., the part of the damping element 34 extending towards the second face 58, the circumferential openings 60 in the outer surface 52 are offset by approximately 90° from the circumferential openings 60 that open at the first face 56 of the damping element 34.

[0029] Due to the offset 62 of the circumferential openings 60 as in Fig. As shown in Figure 6, an overlap of running paths 66 and thus a mutual cancellation of pressure pulses in the circumferential channel 64 can be promoted.

[0030] With regard to the installation position of the damping insert 34 proposed according to the invention, which is essentially cylindrical, its first plan side 56 represents an inflow side for the gaseous medium and its second plan side 58 represents an outflow side, from which the gaseous medium flows into the pressure channel 20, which serves as a buffer, after reduction of the pressure pulse by passing through the at least one damping channel 54.

Claims

[1] Device for damping pressure pulses in a pressure sensor (10) with a housing (14), wherein a damping insert (34) is received in a pressure channel (20), wherein the damping insert (34) is substantially cylindrical and has a first flat side (56) on an upstream side of the damping insert (34), a second flat side (58) on an downstream side of the damping insert (34) and a lateral surface (52), wherein the damping insert (34) has a single circumferential damping channel (54) approximately in the middle, with respect to its axial length, wherein the damping channel (54) is provided as a circumferential groove in the lateral surface (52) and has a rectangular or square flow cross-section, wherein circumferential openings (60) provided in the lateral surface (52) and connected to the damping channel (54) open onto the first flat side (56) and the second flat side (58),wherein the circumferential openings (60) are provided in a 90° orientation and wherein the circumferential openings (60) that open onto the second plan side (58) of the damping insert (34) are arranged offset by approximately 90° with respect to the circumferential openings (60) that open onto the first plan side (56) of the damping insert (34). [2] Device according to claim 1, characterized by , that the damping channel (54) of the damping insert (34) is covered by the wall of the pressure channel (20). [3] Device according to claim 1, characterized by , that the damping insert (34) is mechanically fastened in the pressure channel (20), in particular by hot riveting or joined in the pressure channel (20) by material bonding, in particular by welding in it.

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