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
  • G01F1/66—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 measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
  • G01F1/662—Constructional details
• • 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

Definitions

• the invention relates to a flow sensor for determining the flow velocity of a fluid flowing in a flow channel, having a head part and having a first and a second sound transducer, wherein in each case a sound transducer is arranged at the end of a measuring section and is connected to a subsequent evaluation, the the transit time of a sound wave emitted and received by the sound transducers determines the flow velocity of the fluid.
• the invention further relates to a flow channel for receiving the flow sensor.
• Flow sensors are used, for example, as mass air flow sensors in the intake tract of internal combustion engines in order to determine the intake air mass and to supply the internal combustion engine accordingly with fuel.
• the intake tract here forms the flow channel.
• a flow sensor and a flow channel for receiving the flow sensor are known from DE 33 31 519 A1.
• lateral nozzles are formed on a flow channel, in each of which ultrasound transducers are arranged.
• the ultrasonic transducers define a measuring path that runs at an angle to the flow direction.
• An evaluation circuit connected downstream of the ultrasound transducers determines the transit time of the ultrasound signals along the measurement path and calculates therefrom the flow velocity of the fluid in the flow channel.
• a disadvantage of the known device is that the installation and adjustment of the sound transducer in the neck of the flow channel is expensive. On the one hand, it must be ensured that the transducers are aligned with each other.
• the supply lines for the sound transducers must be routed through the wall of the connecting piece to the outside and from there to the evaluation unit.
• the cable strands must often be performed around the flow channel to the evaluation. Since the length of the measuring section between the one and the other sound transducer of high importance for the
• the sound transducers must be positioned at the greatest possible distance from each other.
• the known from the prior art flow sensors according to the ultrasonic principle relative are large and bulky components.
• the present invention seeks to provide a compact, easy-to-assemble flow sensor that provides good measurement results even in a compact design.
• the invention is also based on the object of specifying a flow channel for receiving the flow sensor.
• the flow sensor can be made extremely compact. Nevertheless, a relatively long measuring distance between the transducers is available, so that a qualitatively high-quality measurement result is achieved.
• the transmitter is arranged in the head part. This has the advantage that the electrical conductors between the transducers and the evaluation can be kept short. As a result, interference of the measurement signals are minimized by interference of electromagnetic waves, which significantly contributes to a good signal quality.
• the sound transducers are arranged symmetrically to the evaluation.
• the transit times of the measuring signals in the electrical conductors between the first sound transducer and the measuring electronics are just as long as between the second sound transducer and the measuring electronics. This symmetry leads to excellent measurement results.
• the sound reflector focuses the sound wave towards at least one of the sound transducers. This focusing effect of the sound reflector allows the use of sound waves of lower intensity, the quality of the measurement results are further improved.
• the sound reflector compensates for the passage of the sound wave. This is very important for the measurement of high flow velocities, since without the compensation of the drift, the sound wave arriving at the sound transducer has a very low intensity. By compensating the drift with the help of the advantageously designed surface of the reflector, a very good measurement result can be achieved even at high flow velocities of the fluid.
• the flow sensor is very flexible and it can be easily manufactured as a vendor part.
• the sound transducers are each separate transmitter or receiver or combined transmitter and receiver. As a combined transmitter and receiver, each transducer can emit a sound wave and receive one, allowing it to traverse the measurement path from both sides. If a transducer is designed as a transmitter and he others as a receiver, the system is very inexpensive to produce.
• the sound signals emitted and received by the sound transducers are ultrasonic signals.
• FIG. 1 shows a cross section through a flow sensor mounted in a flow channel
• FIG. 2 shows a flow sensor for determining the flow velocity
• FIG 3 shows the known from Figure 2 flow sensor in its installed position in the flow channel
• Figure 4 shows another possible embodiment of the sound reflector
• Figure 5 further embodiment of the flow sensor
• Figure 6 is a precise representation of the sound reflector.
• Figure 1 shows a cross section through a flow channel 1, which has a side-mounted nozzle 2 with an opening 3.
• the flow channel 1 is formed here as a tube.
• a flow sensor 4 can be introduced into the interior of the tube 1.
• the flow sensor 4 has a head part 5 in which a printed circuit board 6 is located on a required for the operation of the flow sensor 4 evaluation electronics 17, the components 7 summarizes, is arranged.
• Sidebars 9 are also attached to the head part 5 of the flow sensor 4 and extend into the interior of the tube 1 after the flow sensor 4 has been mounted on the tube 1.
• the side strips 9 hold sound transducers 10 and 11, which define a measuring section 12.
• the measuring section 12 is aligned at an acute angle ⁇ to a flow direction 13 of a fluid 14 flowing in the pipe 1.
• the angle ⁇ between the measuring section 12 and the flow direction 13 is preferably between 40 and 45 degrees.
• the sound transducer 10 During operation of the flow sensor 4, the sound transducer 10, for example, emits a first ultrasonic wave 16. This first ultrasonic wave is received by the sound transducer 11. The sound transducer 11 then emits a second ultrasonic wave 16 which is received by the sound transducer 10. The transit time of the first and the second ultrasonic wave 16 is determined by a transmitter 17, which may be integrated on the circuit board 6 or which is arranged outside of the flow sensor 4.
• the flow velocity v of the fluid 14 in the tube 1 is apart from various disturbing effects that can falsify the measurement result proportional ⁇ t / t up t down , where ⁇ t is the difference of the transit times and t up and t down respectively the transit times in the flow direction 13th or against the flow direction 13 are.
• the arrow denoted by 13 symbolizes below the flow direction and also the flow speed of the fluid 14. From the flow velocity v of the fluid 14, taking into account the temperature on the mass of the pumped fluid 14th getting closed.
• the flow sensor 4 can be used as an air mass meter in the intake tract of an internal combustion engine.
• the fluid 14 is preferably a gaseous medium, in particular air.
• the fluid 14 may also be a liquid, such as gasoline.
• FIG. 2 shows a flow sensor 4 for determining the flow velocity 13 of a fluid 14 flowing in a flow channel 1.
• the flow sensor 4 consists of a head part 5 with a first and a second sound transducer 10, 11. Each of these sound transducers 10, 11 is arranged at the end of a measuring section 12 and connected to a downstream evaluation electronics 17.
• the evaluation electronics 17 are connected to the sound transducers 10, 11 via electrical lines 8.
• the sound transducers 10, 11 are arranged symmetrically with respect to the evaluation electronics 17, whereby the electrical lines 8 have approximately the same length, which in the case of time measurements Significant improvement in the
• the measuring electronics 17 are in turn connected via electrical conductors 8 to an electrical connection 18, which can be designed as a plug and which represents the connection to the subsequent electronics.
• brackets 19 are formed, which carry a sound reflector 15. If, for example, the first sound transducer 10 emits a sound wave 16, it passes to the sound reflector 15 and is deflected there and directed to the second sound transducer 11. The second sound transducer 11 registers the impact of the first sound wave 16 and generates a corresponding signal, which reaches the evaluation electronics 17 via the electrical line 8. Thereafter, the second sound transducer 11 a Sound wave 16 emit that passes through the sound reflector 15 to the first transducer 10. This also registers the impact of the sound wave 16 and generates an electrical signal, which is supplied to the transmitter 17.
• the measuring path 12 is composed of the path from the first sound transducer 10 to the sound reflector 15 and the path from the sound reflector 15 to the second sound transducer 11 and vice versa. From the measured time differences can now be closed to the flow rate 13 of the fluid 14. If the flow sensor 4 is used in the intake passage of an internal combustion engine, then the mass of the intake air can be determined.
• a long measuring section 12 can be realized, wherein the flow sensor 4 can be made very compact and the sound transducers 10, 11 can be arranged symmetrically in a very advantageous manner.
• FIG. 3 shows the flow sensor 4 known from FIG. 2 in its installation position in the flow channel 1.
• the flow channel 1 contains the fluid 14, which may be a gas, in particular air.
• the fluid 14 flows in the flow direction and at the flow velocity, which is indicated by the arrow 13.
• the flow sensor 4 is here introduced into an opening 3 of the flow channel 1.
• the measurement of the mass of the fluid 14 flowing past the flow sensor 4 takes place analogously to the manner described in FIGS. 1 and 2.
• a relatively small flow rate indicated by the arrow 13 indicated by the arrow 13.
• the arrow 13 is much larger and stronger, which is intended to indicate a much higher flow rate.
• the phenomenon of bleeding (also referred to as blowing) of the surge wave 16 occurs.
• the sound wave 16 propagates in space due to atomic and molecular collisions of the fluid particles. If the individual fluid particles move at a very high speed, the sound wave 16 becomes straight Propagation clearly deflected and transported with the vector of the flow velocity 13. The propagation line of the sound wave 16 results as a vectorial superposition of the sound velocity and the flow velocity 13 of the fluid 14, which is indicated by the slightly curved dashed lines.
• the sound reflector 15 is designed such that the sound wave 16 is deflected so that it reaches the center of the first sound transducer 10 despite the drifts. In the illustration in FIG. 3 a, it has been assumed that the sound wave 16 is emitted by the second sound transducer 11, reflected by the sound reflector 15, and guided to the first sound transducer 10.
• FIG. 4 shows a further possible embodiment of the sound reflector 15.
• the structure of the flow sensor 4 in FIG. 4 corresponds to that of the flow sensor 4 in FIG. 3.
• FIG. 4 only the shape of the sound reflector 15 is modified, but again with the aim of the sound wave
• FIG. 5 shows a further embodiment of the flow sensor 4.
• the electrical connection 18 is now attached laterally to the head part 5.
• the sound transducers 10, 11 are located below the transmitter 17, but in turn symmetrically to this.
• the flow sensor 4 according to FIG. 5 now has three sound reflectors 15.
• a sound wave 16 emitted by the first sound converter 10 first reaches the right sound reflector 15 and is guided there to the middle parabolically configured sound reflector 15, which carries the sound wave 16 Wave deflects to the left sound reflector 15, where it is deflected again to then reach the second transducer 11.
• a very long measuring section 12 is realized, which takes place in a very compact flow sensor 4 space.
• FIG. 6 shows a precise representation of the sound reflector 15.
• the sound reflector 15 is supported by holders 19, which are connected to the head part 5, not shown here, of the flow sensor 4.
• the shape of the surface of the sound reflector 15 is important.
• the surface of the sound reflector 15 has a curvature K L along the flow direction 13 and a curvature K Q transversely to the flow direction 13 of the fluid 14.
• the curvatures K L , K Q can be designed in such a way that the sound wave 16 is optimally focused on the center of the first and second sound transducers 10, 11.
• the curvatures K L , K Q of the surface of the sound reflector 15 can be designed such that the drift of the sound wave 16 is compensated so that the sound wave 16 reaches the center of the sound transducers 10, 11 even at high flow velocity 13.
• This advantageous embodiment of the surface of the sound reflector in conjunction with the long measuring section 12 allows the production of very high quality and accurate measurement signals.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Measuring Volume Flow (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38335662

Family Applications (1)

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Cited By (1)

Families Citing this family (7)

Citations (6)

Family Cites Families (11)

• 2006
  • 2006-05-18 DE DE102006023478A patent/DE102006023478A1/de not_active Withdrawn
• 2007
  • 2007-05-11 DE DE112007001054T patent/DE112007001054A5/de not_active Ceased
  • 2007-05-11 WO PCT/EP2007/054551 patent/WO2007134981A1/de active Application Filing

Patent Citations (6)

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