Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
  • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
  • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
  • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F5/00—Measuring a proportion of the volume flow
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/161—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general in systems with fluid flow

Definitions

• the invention relates to a device for measuring the mass of a flowing medium according to the preamble of the main claim.
• a device for measuring the mass of a medium flowing in a line, in particular the intake air mass of an internal combustion engine in which a measuring element, e.g. B. is introduced in the form of a hot wire.
• a measuring element e.g. B.
• considerable fluctuations or pulsations in the flow velocity occur in the bypass duct, the strength of which is dependent on the intake frequency of the individual pistons or on the speed of the internal combustion engine.
• These flow fluctuations falsify the measurement result, namely the flow velocity prevailing on average in the bypass duct and the intake air mass of the internal combustion engine that can be calculated therefrom.
• the intake duct of a brake engine to arrange a flow tube in the form of an inner tube.
• the measuring element is also arranged in a bypass channel, which is located approximately in the middle of the flow tube.
• the inside of the flow tube has friction surfaces which bring about a flow resistance which is dependent on the pulsation strength of the flow. With a high pulsation strength, the flow is therefore displaced into the inner region, i.e. into the region of the bypass channel having the measuring element, due to the friction effects occurring in the edge region of the flow tube, so that a reduction in the display without the flow tube is effectively compensated for with a high pulsation strength of the flow .
• the flow tube known from DE 43 40 882 AI has therefore generally proven itself. The disadvantage, however, is that a loud, annoying whistling noise occurs during practical operation.
• the device according to the invention for measuring the mass of a medium flowing in a line with the characterizing features of the main claim has the advantage that no disturbing whistling noises occur during operation or the whistling noises are at least significantly reduced.
• the structural grooves according to the invention on the outlet end face surrounding the outlet opening prevent the detachment of eddies in the region of the outlet opening of the flow tube, which causes loud noise. It has been shown that the structural grooves according to the invention on the outlet end face surrounding the outlet opening do not reduce the above-described, fluidic advantages of the flow tube which improve the measurement accuracy. Advantageous further developments and improvements of the device specified in the main claim are possible through the measures listed in the subclaims.
• structural grooves with a rectangular, triangular or trapezoidal cross-sectional profile can be used to achieve a particularly effective reduction in noise.
• the structural grooves particularly preferably run radially to the longitudinal axis of the flow tube and are arranged at uniform angular intervals on the outlet end face. This results in a uniform segmentation of the outlet end face, which is advantageous for the suppression of noise.
• the inlet end face surrounding the inlet opening of the flow tube is preferably unstructured in order not to increase the flow resistance in the region of the inlet opening.
• Fig. 1 is a side view of a first embodiment of the invention
• FIG. 2 is an enlarged, partially sectioned side view of a measuring module used in the exemplary embodiment of the device according to the invention shown in FIG. 1,
• Fig. 3 is a view of the end portion of the one shown in Fig. 1
• Embodiment used flow tube in the direction marked III in Fig. 1,
• Fig. 4 is a view corresponding to Fig. 3 of a second, modified
• Fig. 5 is a view corresponding to Fig. 3 of a third, modified embodiment
• Fig. 6 is a view of the flow tube used in the embodiment shown in Fig. 1 in the marked VI in Fig. 1 4
• the device 1 shown in section in FIG. 1 serves to measure the mass of a medium flowing in a line 2, in particular the intake air mass of an internal combustion engine.
• the device 1 can e.g. B. by means of unillustrated at the ends provided connecting flanges as a mountable intermediate piece in an intake line through which the internal combustion engine sucks air from an air filter, not shown, from the environment, which is provided via a throttle valve assembly, not shown, which is provided for controlling the intake air mass, in reaches a combustion chamber of the internal combustion engine.
• the device 1 comprises a flow tube 3, which is introduced approximately centrally in the line 2 and is attached to the inner wall 5 of the line 2 by means of spacers 4, which are only shown schematically.
• spacers 4 can be provided, which, for. B. are arranged angularly offset from one another by 120 ° or 90 °.
• the flow tube 3 is shaped like a cylinder and extends around a longitudinal axis 6, which coincides with the longitudinal axis of the line 2.
• the flow tube 3 has an inlet opening 9 facing the main flow direction illustrated by the arrow 8, which is surrounded by an inlet end face 10.
• Axially opposite the inlet opening is an outlet opening 11 which is surrounded by an outlet end face 12.
• a measuring module 17 to be described in more detail, which has a measuring channel 33 tapering along the main flow direction 8 for receiving the measuring element 20.
• a deflecting duct 34 adjoins the measuring duct 33, which, as can be seen in FIG. 2, is S-shaped and opens into the flow tube 3 at a deflecting duct outlet 46.
• the measuring element 20 is aligned centrally with the measuring channel 33 and is located in the region of the longitudinal axis 6 of the flow tube 3.
• the structure of the measuring module 17 is described in more detail below with reference to FIG. 2, which shows a sectional side view of the measuring module 17.
• the measuring module 17 has a slender, cuboid shape that extends radially in the direction of a longitudinal axis 23 and is in a recess of the flow tube 3, not shown 5 introduced, for example, pluggable.
• the longitudinal axis 23 of the measuring module 17 is oriented perpendicular to the longitudinal axis 6 of the flow tube 3 in the preferred exemplary embodiment shown.
• the main flow direction is also illustrated in FIG. 2 with the arrows 8.
• the measuring module 17 can, for. B. be made of plastic by injection molding.
• the measuring element 20 projects centrally into the measuring channel 33 and is connected via electrical connecting lines 22 to an evaluation circuit (not shown).
• the measuring element 20 is preferably produced by etching out a semiconductor body, for example a silicon wafer, in what is known as a micromechanical construction and has a structure which, for. B. is known from DE 195 24 634 AI.
• the measuring element 20 has a membrane-shaped sensor region 21 which is formed by etching and which is delimited by the line II in FIG. 2.
• the sensor region 21 has an extremely small thickness and has a plurality of resistance layers, also formed by etching, which resist at least one temperature-dependent measurement and, for example, form a heating resistor. It is also possible to provide the measuring element 20 as a so-called hot film sensor element, the structure of which can be found, for example, in DE 36 38 138 AI.
• the individual resistance layers of the measuring element 20 or the sensor region 21 are electrically connected by means of connecting lines 22 running inside the measuring module 17 to an evaluation circuit, not shown, which contains, for example, a bridge-type resistance measuring circuit.
• the evaluation circuit is e.g. B. housed in a carrier part or a holding part of the measuring module 17.
• the measuring module 17 has a measuring channel 33 extending in the axial direction and a z. B.
• An S-shaped deflection channel 34 extends in the direction of the central axis 6 of the flow tube 3 from an opening 36, for example, which has a rectangular cross section, to an opening 35.
• the measuring channel 33 is from a surface 38 distant from the central axis 6 and a lower surface 37 closer to the central axis 11 and two side surfaces are limited.
• the plate-shaped measuring element 20 is oriented in the measuring channel with its greatest extent radially in the direction of the longitudinal axis 23 and is divided symmetrically by the latter, so that the medium flows around the measuring element 20 approximately parallel to the central axis 6.
• the medium flows from the inlet opening 36 of the measuring channel 33 to the measuring element 20 and from there into the deflection channel 34 in order to leave the deflection channel 34 in the radial direction with respect to the longitudinal axis 6 from the deflection channel outlet 46.
• Deflection duct outlet 46 like deflection duct 34, has, for example, a rectangular cross section and is provided on a lower outer surface 45 of measuring module 17 oriented parallel to longitudinal axis 6. Contrary to the main flow direction 8, the lower outer surface 45 is adjoined by a boundary surface 42 of the measuring module 17 opposite the main flow direction 8, which leads upstream of the inlet 36 in a rounded form from the lower outer surface 45 to the lower surface 37 of the measuring channel 33 as far as the inlet 36.
• the flow tube 3 shown in FIG. 1 forms, with an inner surface 50 and an outer surface 51, friction surfaces 52, on which, in the case of pulsating flow when flowing along, due to flow effects such as vortices induced on the friction surfaces 52 or detachments occurring due to the pressure drop to the inner wall 50 Flow is more or less obstructed, so that in the area of the inner wall 50 there is a variable flow resistance that is dependent on the intensity of the pulsation.
• the flow tube 3 therefore acts as a flow straightener.
• the measuring element 20 generally tends to display a reduction when the pulsating flow occurs when the flow tube 3 is not present.
• the flow tube 3 due to the flow resistance dependent on the pulsation strength of the flow, causes the flow to be displaced into the inner region of the flow tube 3, where the measuring module 17 with the measuring element 20 is arranged. Compared to a non-pulsating flow, an increased flow velocity therefore occurs in the case of a strongly pulsating flow in the inner region of the flow tube 3, which leads to a compensation of the deficiency indicator which is otherwise present.
• the flow tube 3 has the disadvantage that loud whistling noises occur as undesirable disturbing noises during operation.
• the disturbing noises presumably stem from the fact that vortices detach at the outlet opening 11 of the flow tube 3 with a relatively high repetition frequency, which leads to the whistling noise described.
• the inventive design of the flow tube 3 counteracts this annoying whistling noise.
• FIG. 3 shows a radial view of the end region of the flow tube 3 in the region of the outlet opening 11. The direction of view on which FIG. 3 is based is identified by the arrow III in FIG. 1.
• the structure grooves 53 have a rectangular cross-sectional profile.
• FIGS. 4 and 5 show alternative exemplary embodiments, with FIGS. 4 and 5 likewise showing a radial view of the end region at the outlet opening 11 of the flow tube 3.
• the structure grooves 53 have a triangular cross-sectional profile.
• the structure grooves 53 are separated by webs 54 with a trapezoidal cross-sectional profile.
• the structure grooves 53 have a trapezoidal cross-sectional profile.
• the structural grooves 53 are separated here by webs 54 with a triangular cross-sectional profile.
• various other embodiments of the structural grooves are also conceivable, in particular part-circular structural grooves, trapezoidal structural grooves or roughening by means of irregularly deep and irregularly shaped, radially extending structural grooves 53.
• the structural grooves 53 largely prevent or at least suppress detachment of eddies on the outlet end face 12 surrounding the outlet opening 11. Practical tests have shown that the measure according to the invention can achieve a significant reduction in the noise that occurs.
• the function of the flow tube 3 as a flow straightener with the properties described above which improve the measurement accuracy in the case of strongly pulsating flows is not impaired by the structure grooves 53 according to the invention. Since in particular when using the device 1 in motor vehicles to measure the intake air mass of the Bremiki'aftmaschine whistling noises are extremely unpleasant and significantly impair driving comfort, the measure according to the invention achieves a considerable improvement.
• FIG. 6 shows a front view of the flow tube 3 corresponding to the viewing clearing marked VI in FIG. 1.
• the measuring module 17 has been omitted in FIG. 6 to simplify the illustration.
• the radially extending structural grooves 53 which are separated from one another by the webs 54, can be clearly seen on the outlet end face 12 surrounding the outlet opening 11 of the flow tube 3.
• the structural grooves 53 are not rectangular, as in the exemplary embodiment shown in FIGS. 1 and 3, but are designed with a triangular cross-sectional profile in accordance with the exemplary embodiment shown in FIG. 4. 8th
• the structural grooves 53 are distributed at uniform angular intervals over the outlet end face 12, so that a uniform segmentation of the outlet end face 12 is achieved.
• the inlet end face 10 surrounding the inlet opening 9 of the flow tube 3 is preferably unstructured, i. H. the inlet end face 10 has no structural grooves in order not to increase the flow resistance.
• the inlet end face 10 can be rounded or streamlined to further reduce the flow resistance.
• the device 1 is then also suitable for measuring flows with different main flow directions.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Aviation & Aerospace Engineering (AREA)
• Combustion & Propulsion (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Measuring Volume Flow (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7863926

Family Applications (1)

Country Status (7)

Families Citing this family (22)

Family Cites Families (5)

• 1998
  • 1998-04-08 DE DE19815658A patent/DE19815658A1/de not_active Withdrawn
• 1999
  • 1999-01-28 KR KR1019997010541A patent/KR100580135B1/ko not_active IP Right Cessation
  • 1999-01-28 JP JP55100599A patent/JP2002506529A/ja not_active Ceased
  • 1999-01-28 CN CNB99800507XA patent/CN1175252C/zh not_active Expired - Fee Related
  • 1999-01-28 EP EP99907286A patent/EP1019678A1/de not_active Withdrawn
  • 1999-01-28 US US09/445,403 patent/US6272920B1/en not_active Expired - Fee Related
  • 1999-01-28 WO PCT/DE1999/000201 patent/WO1999053275A1/de active IP Right Grant

Non-Patent Citations (1)

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