WO1995033185A2

WO1995033185A2 - Probe for measuring the speed or rate of flow of a flowing medium, in particular for air volume measurement, and pressure cell in particular for use with such a probe

Info

Publication number: WO1995033185A2
Application number: PCT/DE1995/000647
Authority: WO
Inventors: Werner Schlattl
Original assignee: Bavaria-Tech Werner Schlattl
Priority date: 1994-05-26
Filing date: 1995-05-17
Publication date: 1995-12-07
Also published as: WO1995033185A3; EP0721571A1

Abstract

A probe for measuring the speed or rate of flow of a flowing medium consists of an elongated probe body perpendicular or transversely oriented to the direction of flow and that extends into a chamber through which flows the medium. At its free end, the probe body has a first measurement opening that opens into a first channel and lies in a plane perpendicular to the probe for measuring the static pressure of the flow, as well as a second measurement opening for measuring dynamic pressure that opens into a second channel separate from the first channel. The probe is preferably connected with its two channels to a differential pressure cell and forms together with said cell an air volume measurement device for use in an internal combustion engine, for example.

Description

Probe for measuring the flow velocity or flow quantity of a flowing medium, in particular for measuring the air quantity and pressure transducer, in particular for use with such a probe

The invention relates to a probe for measuring the flow velocity and thus for measuring the amount of a flowing medium.

The invention relates to a pressure cell, in particular for use with such a probe, according to the preamble of claim 11, and to a device for measuring an amount of air or gas, consisting of a probe and a pressure cell, according to the preamble of claim 23.

In the case of internal combustion engines in particular, the most exact possible measurement of the amount of air or mixture flowing through an intake duct is essential for optimal control of the fuel supply.

The object of the invention is to show a probe with which a speed measurement or quantity measurement of a flowing medium is reliably possible with simple means.

To solve this problem, a probe is designed in accordance with the characterizing part of patent claim 1. The basic mode of operation of the probe according to the invention is based on a difference measurement between a static and a dynamic pressure.

The main advantages of the probe according to the invention are that the static pressure measurement takes place in the flow and not at the edge of this flow or in a flow channel. The static pressure measurement is therefore independent of the shape of the channel.

Another advantage of the probe according to the invention is that, with the exception of the means used for the pressure difference measurement, for example a pressure cell used for the pressure difference or the measuring membrane there, no mechanical moving elements are necessary. This not only ensures a high level of operational reliability even in harsh environments, but also virtually eliminates external influences on the measurement result, in particular due to acceleration or gravitational forces.

Another advantage of the probe according to the invention is that it can be expanded in a simple construction and can therefore be manufactured inexpensively.

The probe according to the invention is also particularly easy to install in flow channels, in particular also in air intake channels of internal combustion engines.

Because of the simple construction and reliable method of operation, the probe according to the invention also allows, in the case of an internal combustion engine, at least one separate probe for each individual cylinder or for its intake duct To be provided so that each cylinder of an internal combustion engine can then be individually controlled with respect to the fuel supply via the measurement signals supplied by these probes or their transducers.

In internal combustion engines, but also in many other areas of technology, it is necessary or desirable to measure the pressure of a flow medium, namely air and / or gases with high accuracy. There is also the problem with internal combustion engines of the precise measurement of the air or the air / fuel mixture flowing through an intake system (intake duct or intake pipe) and directed to a combustion chamber or a cylinder, in order to be able to control an optimal fuel supply and thus an optimal combustion.

The object of the invention is therefore also to show a pressure transducer which delivers flawless measurement results with high accuracy even under difficult environmental conditions.

To solve this problem, a pressure cell is designed according to the characterizing part of claim 11.

In a further development, the invention also relates to a device for measuring the mass or amount of a gaseous flow medium flowing through a flow channel, preferably air, and in particular an air mass meter with which the amount of air or gas supplied to internal combustion engines can be measured very precisely and without interference and which delivers a signal corresponding to this amount of air. Such a device, which comprises at least one probe and at least one pressure transducer, is designed in accordance with the characterizing part of patent claim 23.

The pressure transducer according to the invention has the advantage that the pressure measurement is free of hysteresis with high resolution, in particular because the convex design of the mirror surface of the mirror element when the optical axis of the mirror element is arranged transversely to the axis of the movement of the membrane results in a reflection of the Luminous flux emerging from the light transmitter at different positions of the membrane and thus of the mirror element is carried out in different areas of the concave curved mirror surface such that not only does a different angle depending on the position of the membrane result between the incident and the reflected luminous flux, but also a different diameters dependent on the respective position of the membrane for the luminous flux incident on the light receiver and thus a light density dependent on the position of the membrane of the light incident on the light receiver light flux.

Small movements of the membrane thus lead to large changes in the measurement signal, which results in a high sensitivity. Furthermore, the measurement signal is only slightly influenced by the deposition of foreign and dust particles, for example on the mirror surface of the mirror element. The membrane and the mirror element can be manufactured with a low mass, so that acceleration forces do not falsify the measurement result, so the pressure cell is particularly suitable for use in vehicles. The size of the mirror surface is selected so that it is in any case larger than the cross section of the light flux of the light transmitter striking the mirror surface, so that the reflection of this light flux at different areas of the mirror surface is possible in different positions of the membrane.

In its preferred embodiment, the pressure transducer is designed to measure a differential pressure, preferably to measure the differential pressure between a static and a dynamic pressure in a flow channel. The load cell is then part of the device for measuring the mass or quantity of a flow medium flowing through the channel, preferably part of an air mass meter for measuring the quantity of air flowing through the intake duct of an internal combustion engine.

The output signal of the pressure load cell or several pressure load cells is combined with other parameters for measuring the flow rate or mass in an electrical control device, in particular with the temperature of the flow medium and / or with the ambient pressure.

Further developments of the invention are the subject of the subclaims.

The invention is explained in more detail below with reference to the figures using an exemplary embodiment. Show it:

Figure 1 in a simplified representation and in longitudinal section a probe according to the invention.

Fig. 2 is a top view of the probe of Fig. 1; 3 shows a schematic illustration of an internal combustion engine having a plurality of cylinders;

Fig. 4 in a simplified representation and in section a pressure cell according to the invention;

5 is a simplified representation of a plan view of the left side of the diaphragm of the pressure cell in FIG. 4 and of the mirror element and the light-transmitting and detector unit;

Figures 6 and 7 are a graph for explaining the operation of the pressure cell;

8 in a simplified representation and in the block diagram further elements forming an air knife;

9 shows in a simplified representation and in the block diagram an internal combustion engine having a plurality of cylinders and with an air mass meter common to these cylinders with individual control of the cylinders;

Fig. 10 is a graph showing, as a function of time, the signal supplied by the pressure sensor and corresponding to the pressure in the intake duct of the engine of Fig. 9, in comparison to the signal of a conventional air flow meter;

11 shows a further possible embodiment of the invention in a representation similar to FIG. 9;

Fig. 12 in a simplified representation and in section a further possible pressure cell for use with the Probe according to Figure 1;

13 shows a detail of the pressure cell of FIG. 12.

The probe 1 shown in the figures and used to measure the flow velocity of a flowing medium, in particular to measure the flow velocity of air, gases or air and / or gas mixtures, is perpendicular to the direction of flow in one of the two with its longitudinal extension or longitudinal axis L. Medium through which space or channel is arranged. The main direction of flow of the medium is indicated in FIG. 1 by A and the direction of a possible backflow by arrow B.

The probe 1 consists essentially of an inner pipe section 2 and an outer pipe section 3, which encloses the inner pipe section over a partial length, in such a way that two channels are formed, namely the channel 4 lying coaxially with the longitudinal axis in the inner pipe section 2 and the annular channel surrounding the inner tube section 2, which is delimited to the outside by the tube section 3 and concentrically surrounds the longitudinal axis L.

At the upper end in FIG. 1, the channel 5 is closed by a conical wall section 6 which merges into the pipe section 2 on the inside and into the pipe section 3 on the outside. A further wall section 7, which merges into the pipe section 2 on the inside and into the pipe section 3 on the outside, closes the channel 5 at the lower end in FIG. 1. The inner pipe section 2 projects with a length 2 'over the upper, closed end of the pipe section 3 or over the wall section 6 there. Likewise, the inner pipe section 2 protrudes with a length 2 ″ over the lower, closed end of the wall section 7. The inner pipe section 2 is open at its upper end (measuring opening 4 ') and in the area thereof Opening provided with a plate-like, radially projecting flange or section 8, which is flat on its upper side, ie on the side facing away from the length 2 'and there has the measuring opening 4' of the channel 4. On the underside, section 8 is frusto-conical, tapering towards the bottom, in such a way that the edge of the section is designed like a knife.

The lower end of the pipe section 2 or the channel 4 is also open. A pressure transducer, not shown, for measuring a static pressure P1 is connected to this end.

The outer pipe section 3 has an opening 9 slightly below the wall section which tapers in the shape of a truncated cone, via which the channel 5 communicates with the outside. In the area of the lower end there is a connection 10 which is connected to the channel 5 and via which the channel 5 can be connected to the pressure meter 20 shown in FIGS. 4 and 5 for measuring the dynamic pressure P2. In the embodiment shown, the opening 9 and the connection 10 are located on different sides of this longitudinal axis with respect to the longitudinal axis L.

The probe 1 is oriented in such a way that the opening 9 is located on that side of the probe 1 on which the main flow direction A strikes directly.

With the probe, the flow velocity of the medium and thus also the amount of the fluid flowing through a channel, for example per unit time, can be optimally determined by determining the static pressure P1 and the dynamic pressure P2 Medium are determined.

The advantages of probe 1 include also that the static pressure measurement takes place directly in the flow and not at the edge of a flowed-through space or channel and is therefore independent of the shape of the channel. Another important advantage of the probe 1 is that a measurement of possible reverse currents is possible.

The probe 1 is still insensitive to oblique flow, i.e. the adjustment of the probe 1 with respect to the direction of flow is not critical. Since channels 4 and 5 as well as the openings of these channels, i.e. in particular, the opening 9 can also have a large cross-section, a highly dynamic measurement with the probe 1 is possible or inertia in the measurement is avoided. Another significant advantage is the relatively simple construction of the probe 1 and the possibility of arranging this probe in flow channels in a particularly simple manner.

As shown in FIG. 3, the probe 1 is also particularly suitable as a component of an air mass or air flow meter in the air intake duct of internal combustion engines for the control of such engines. In this case, an individual measurement is then preferably carried out for each cylinder 12 of such an engine 1, ie, such a probe 1 is arranged in the air intake duct 13 of each cylinder 12. Each probe 1 is then provided with a converter device which evaluates the pressures P1 and P2 and / or converts it into electrical signals, which is connected via signal lines 14 to central control electronics 15 for the motor which (control electronics) correspond to those of the probes 1 supplied signals, for example, individually control the fuel supply to the individual cylinders 12. In the embodiment shown, the intake ducts 13 open into a common air duct 13 '. To determine the difference between the static pressure Pl and the dynamic pressure P2, the pressure load cell 30 shown specifically in FIGS. 4 and 5 is used. This essentially consists of a housing 31, which is made of a circular disk-shaped membrane 32 made of metal and attached to it Is circumferentially clamped on the housing 31, is divided into two outwardly and mutually sealed sub-spaces 33 and 34, of which one sub-space, for example the sub-space 33, is subjected to the static pressure, ie is connected to the channel 4 and the other sub-space 34 applied with the dynamic pressure, that is connected to the channel 5 of the probe 1. The pressure load cell 30 is preferably provided integrated on the corresponding probe 1, so that very short lengths ensuring high dynamics and an accurate measurement result are obtained for the channels or for the connections between the measurement openings 4 'and 9 and the associated subspaces 33 and 34 surrender.

To detect the deflection of the membrane 32 as a function of the pressure difference, a mirror element 35 is fastened in the middle of the membrane 32, which in the embodiment shown is formed by a metal plate forming a concave mirror surface 36 and protruding from the membrane 32 into the partial space 33 is. The mirror surface 36 is only curved in one plane in the embodiment shown, i.e. In the embodiment shown, the mirror surface 36 corresponds to part of a circular cylinder surface with a cylinder axis running parallel to the plane E of the membrane 2 and thus perpendicular to the axis and / or deflection direction A of the membrane 32 and perpendicular to the plane of the drawing in FIG. 4.

Opposite the concave mirror surface 36 is a light transmission and detector unit 37 at a predetermined distance, - ll -

For example, a reflex light barrier, which contains an infrared light transmitter 39 in the form of an IR diode and an infrared light receiver 40 in the form of a photo transistor in a common housing 38. The unit 37 is arranged in such a way that the IR transmitter 39 and the IR receiver 40 in the illustration selected for FIG. 4 are perpendicular to the plane of the drawing in FIG. are mutually offset parallel to the axis of curvature of the mirror surface 36, both with their light exit opening or light entry opening formed by a lens-like body facing the mirror surface 36 and with their optical axes define a plane M 'which is perpendicular to the plane of the drawing in FIG. 4 lies.

M in FIG. 4 denotes a plane that runs radially to the curvature of the mirror element 35 and includes the curvature or cylinder axis as well as the optical axis of this mirror element and is parallel to the plane E of the membrane 32. In the embodiment shown, the plane M is the central plane to which the mirror surface 36 is formed symmetrically. The diaphragm 22 is deflected perpendicular to the plane M.

The optical axis of the measuring arrangement comprising the mirror element 35 and the light path (between the transmitter 39 and the receiver 40) is thus parallel to the plane of the membrane 32 and perpendicular to the deflection or movement of this membrane.

The unit 37 is adjusted, taking into account the curvature of the mirror surface 36 and the focal points of the lenses on the transmitter 39 and receiver 40, in such a way that in an assumed end position of the movement or the stroke of the diaphragm 2 in the direction of the axis A, the axes of the The transmitter 39 and the receiver 40 are also in the plane M, ie the planes M and M 'coincide, and the entire luminous - 1.2 -

Area of the transmitter 39 is mapped on the active area of the receiver 40, and as far as possible to fill the format, i.e. the emitted luminous flux 41 is reflected in the luminous flux 42 in such a way that the cross section of the luminous flux 42 incident on the receiver 40 is equal to the opening of the receiver 40. In this first position, the greatest amount of light hits the receiver 40, so that it accordingly delivers the largest signal at its output.

If the diaphragm 32 is deflected from this first position due to the changing differential pressure in the subspaces 33 and 34 and the mirror element is thereby moved relative to the plane M ', which is determined by the optical axes of the transmitter 39 and the receiver 40, so not only is the light from the transmitter 39 reflected on the mirror surface 36 such that only a part of the opening of the receiver 40 is struck by the luminous flux 42, but at the same time there is an increase in the cross section of the reflected luminous flux 42, ie a reduction in the light density of the luminous flux incident on the receiver 40. This ensures that even small deflections of the membrane 32 cause a strong change in the signal delivered by the receiver 40.

These aforementioned relationships are shown in FIGS. 6 and 7 for two assumed end positions of the deflection of the membrane 32. The mirror surface 36 is shown in each of these figures, and the double arrow A indicates the deflection of the membrane 32 and thus the movement of the mirror element or the mirror surface 36. The IR transmitter and the IR receiver are each offset perpendicular to the plane of the drawing in FIGS. 6 and 6 7. The two interrupted, parallel horizontal lines 43 each delimit the light entry opening or opening of the IR receiver, which (light entry opening) in the present embodiment is equal to the light exit opening of the IR transmitter. The interrupted, vertical line 44 indicates the cross section that the reflected light bundle 42 has when it strikes the IR receiver 40.

6, the center plane M of the mirror surface 36 and the plane M 'form a common plane. Due to the aforementioned adjustment of the unit 37, the light of the IR transmitter 39 is completely reflected on the IR receiver 40, in such a way that the diameter 44 of the incident, reflected luminous flux 42 is equal to the opening cross section 43 of the IR receiver 40 . The upper and lower edges of the light beam 41 are designated by 45 and 46 in FIG. 6. These edges are reflected on the mirror surface 36 symmetrically to the center plane M.

In Fig. 7, the corresponding conditions are shown for the case - that the mirror surface 36 has been moved downward in the direction of the axis A, namely by the stroke H, so that the two planes M and M 'offset from each other by this stroke are. As shown in FIG. 7, in this case the reflection of the light bundle 41 on the mirror surface 36 is no longer symmetrical to the central axis M, ie the accepted edge beam 45 of the light bundle 41 is at a greater distance from the surface than in FIG Center axis M reflects, so that due to the different orientation of the mirror surface at this reflection point there is an increase in the angle between the incident edge ray 45 and the reflected edge ray 45 '. The lower edge beam 46 of the light bundle 41 is reflected at a point on the mirror surface 36 which, in comparison to FIG. 6, the central axis M _First 4 _

is closer, so that there is a reduction in the angle between the lower edge beam 46 and the reflected edge beam 46 ', with the result that the reflected light flux 42 incident on the IR receiver 40 ver¬ ver¬ not only opposite the opening 43 of the light receiver 40 is pushed, that is to say only a part of the opening is struck by the light flux 42, but the reflected light flux 42 also has in the plane of the receiver 40 a diameter 44 which is substantially larger than in FIG. 6, which corresponds to a reduction in the light density.

In FIG. 7, this is shown again to the left of the mirror surface 36 by two circles. The circle 43 'defines the opening of the IR receiver 40. The circle 44' defines the diameter of the reflected luminous flux 42 incident on this receiver. The signal supplied by the IR receiver 40 corresponds to the hatched area, which is only one A fraction of the area of the circle 44 and thus the amount of light of the reflected luminous flux 42. In the position of the mirror surface 36 shown in FIG. 6, in which the diameter of the reflected light flux 42 at the IR receiver 40 is equal to the opening 43, that is to say the circles 43 'and 44' are congruent, the total amount of light of the reflected light flux 42 arrives the IR receiver 40.

If it is assumed that a deflection of the diaphragm 32 in an initial position in which there is no differential pressure between the two partial spaces 33 and 34 occurs only in one direction, the state shown in FIG. 6 corresponds to this initial position, for example. If a deflection of the membrane 32 is to be expected in both directions, the state shown in FIG. 6 corresponds, for example, to the position which the membrane has in one direction at the maximum deflection, so that despite the use of only a single mirror - - 1.5 -

element and a single unit 37 an output signal is received at the receiver 40, which reflects not only the size but also the direction of the deflection of the membrane 32.

In principle, designs are also conceivable in which two or more mirror elements 35 with associated units 37 are provided.

8 shows in a block diagram the complete design of a gas and / or air flow meter. The probe 1 and the pressure transducer 30 are again shown with the opto-electrical detection unit formed by the mirror element 35 and by the component 37 or by the light transmitter 38 and the light receiver 39.

Designated at 48 is control electronics which, on the one hand, supply the operating voltages for the IR transmitter 39 and the IR receiver 40 and, on the other hand, the output signal of the IR receiver 40 is supplied. Connected to the circuit 48 is a temperature sensor 49, which is arranged in the flow path of the medium to be measured and is, for example, a temperature-dependent resistor (PT, NTC). Connected to the circuit 48 is a sensor 50 measuring ambient pressure, which e.g. is formed by a further pressure cell 30 or another pressure sensor.

With the aid of the signals from the temperature sensor 49 and the pressure sensor 50, the signal supplied by or derived from the pressure sensor 30 or from the IR receiver 40 is modified such that the temperature of the signal at the output 51 increases as the temperature measured by the sensor 49 increases the circuit 48 reduced and increased with falling temperature - 1.6

and vice versa is increased with increasing ambient pressure and reduced with decreasing ambient pressure. The temperature and the ambient pressure can be taken into account in a particularly simple manner in that with the sensor 49 the brightness of the diode of the IR transmitter 39 is inversely proportional to the temperature profile and with the sensor 50 the signal supplied by the IR receiver 40 or its amplification is proportional to Ambient pressure is changed.

The air mass meter shown in FIG. 8 is used to control an internal combustion engine, in which, according to the illustration in FIG. 3, a separate probe 1 with associated pressure sensor 30 is provided for each cylinder 12 or intake duct 13. The control electronics 48 then have a separate input for each probe 1 and a separate output 51 for each cylinder 12. However, the probes 49 and 50 are preferably provided only once. The signals supplied by the individual pressure transducers 30 are processed individually, so that in each case an output signal is generated individually for each cylinder at the respective output 51, which corresponds to the amount of air measured at this cylinder, taking into account the sensors 49 and 50 determined temperature and ambient pressure.

Since the probe 1 is highly dynamic, i.e. can be designed in such a way that it enables the respective values of the pressures P1 and P2 to be measured with an extremely short time delay at a common measuring range or in the immediate vicinity, in contrast to the motor control system shown in FIG. 3, a control system is also appropriate 9 and 10 possible.

FIG. 9 shows, in a representation similar to FIG. 3, a further possible embodiment in which a single probe 1 at the entrance of a common air intake duct 13 'is one or more - 1.7

Cylinder 12 having an internal combustion engine is provided. The probe 1 is provided with a converter device which evaluates the pressures P1 and P2 and converts them into electrical signals, which is connected via a signal line to control electronics 53 for the engine which, in accordance with the signal supplied by the probe 1, supply the fuel to the individual Controls cylinder 12 individually. The transducer device which converts the pressures P1 and P2 into electrical signals is the pressure load cell 30.

Fig. 10 shows in a diagram as a time-changing curve 54 the signal supplied by the pressure meter 30 on the signal line 52 with the engine 11 running, in comparison to the signal of a conventional hot-film air mass meter, as was previously the case for air mass measurement in motor vehicles is used.

The curve 54 shows not only with its upper amplitudes in a very pronounced form the positive air flow, ie the flow in the respective cylinders or in the direction of arrow B, and with its lower amplitudes one in the intake pipe 13 'or at the measuring point there Existing negative flow (against arrow B), but due to the pronounced upper amplitudes or peaks, which each correspond to the intake stroke of one of the cylinders 12, is also an individual evaluation of each amplitude or half-wave and in particular each positive half-wave as well as a temporal Allocation to the respective cylinders 12 is possible, taking into account a signal that is supplied to the control electronics 53 via a signal line 56, for example from a signal generator or the ignition, and always when the engine 11 reaches a predetermined rotational position or has made a predetermined number of revolutions, for example with each he fourth - 1 .8 -

Revolution. On the basis of the control signal on the signal line 56, the signal value present at the signal line 52 at any time, in particular also a positive half-wave of the curve 54, can be unequivocally assigned to the cylinder 12 performing the respective intake stroke by the control electronics 53 and the fuel supply to this cylinder be controlled accordingly.

It goes without saying that the control electronics 53 are also supplied with the signal from the sensor 50 (ambient pressure) and preferably also the signal from the sensor 49 (air temperature). In principle, however, it is also possible to process the signals supplied by the pressure cell 30 and the additional sensors 49 and 50 in separate control electronics, the output signal of which is then fed to the control electronics 53.

The embodiment shown in FIG. 9 has the advantage that individual control of a plurality of cylinders 12 of an internal combustion engine 11 is possible with only a single sensor 1 and associated pressure cell 30.

FIG. 11 shows, as a further embodiment, an internal combustion engine having a plurality of cylinders 12 together with the common intake duct 13 'and a duct 57 common to all the cylinders 12, which serves to discharge the combustion gases and leads to the exhaust, not shown, of the motor vehicle with catalyst. In the channel 57 there is also a probe 1 with a pressure sensor 58, with which the flow velocity of the combustion gases and their change are measured. The pressure transducer 58 provides at its output a signal corresponding to the signal in FIG. 10, which signal consists of several pulses following in time or put together waves. Each pulse corresponds to the amount of exhaust gas emitted by a cylinder 12 to the channel 57 after the combustion process.

If there is no combustion in one of the cylinders 12 due to a malfunction, for example of the ignition system and / or due to an insufficient amount of supplied fuel, then the corresponding pulse is missing in the signal emitted by the pressure sensor. From this, the control electronics 53, which is also connected to the pressure transducer 58, can conclude that there is no combustion process in the cylinder 12 in question and can be determined on the basis of the signal and, for example, initiate a control measure to counteract this malfunction and / or issue an error message to the user of the vehicle. The particular advantage here is that the catalyst in the exhaust system is not overheated or damaged by excessive amounts of unburned fuel.

FIGS. 12 and 13 also show a simplified pressure cell 20 which can be used for evaluating the static pressure P1 and the dynamic pressure P2 and essentially consists of a housing 21 and a membrane 32 which divides the interior thereof into two subspaces. One subspace is then connected to the inner tube 4 of the probe 1 and the other subspace to the connection 10, so that the membrane 22 is deflected by the differential pressure. To detect this deflection, a plate 23 is attached to the membrane 22, which is arranged in a plane perpendicular to the plane of the membrane. According to FIG. 13, one side of the plate 23 is provided with a surface which partly has a darker region 24 and partly a lighter region 25. A light beam 26 from a light source 27 is directed onto this surface. The light reflected from the surface is detected by a light detector 28 2.0 -

detected. The light source 27 and the light detector 28 form, for example, a light barrier-like electronic component.

In the absence of deflection of the membrane 22, i.e. if there is no pressure difference, the light beam 26 strikes the boundary line between the surfaces 24 and 25. Depending on the deflection of the membrane 22, the light beam 26 strikes the lighter surface 25 or the darker surface 24. The amount of light reflected at the light detector 28 is therefore a function of the deflection of the membrane 22 and the differential pressure or the flow rate of the medium.

The invention has been described above using exemplary embodiments. It goes without saying that changes and modifications are possible without thereby departing from the concept which bears the invention.

Reference list

probe

Pipe piece ', 2 "length

Pipe section, 5 channel, 7 wall section, plate-shaped head or section

opening

Connection

engine

Cylinder, 13 'air intake duct

Signal line

Control electronics

Pressure cell

casing

membrane

Tile, 25 area

Beam of light

Light source

Light detector

Pressure cell

casing

Membrane, 34 compartments

Mirror element

Mirror surface optoelectric unit

casing

IR transmitter

IR receiver , 42 luminous flux, 44 line ', 44' circle, 46 edge beam ', 46' reflected edge beam area control circuit temperature sensor pressure sensor output signal line control electronics, 55 curve signal line channel pressure sensor

Claims

1. Probe for measuring the speed or flow rate of flowing media, consisting of an elongated probe body which is oriented with its longitudinal extension or longitudinal axis (L) transversely or perpendicularly to the direction of the flow and with one end reaching into the flow and there has a first measuring opening (4 ') opening into a first channel (4) and lying in a plane perpendicular to the longitudinal extent (L) of the probe for measuring a static pressure (Pl) of the flow, and that a second measuring opening (9) on the probe body on a second, separate from the first channel (5) for measuring a dynamic pressure (P2) is provided, and that the second measuring opening (9) is arranged in a plane perpendicular or transverse to the direction of flow.

2. Probe according to claim 1, characterized in that the first and the second channel (4, 5) each with a pressure gauge (20, 30) or with a pressure probe for generating a static pressure (Pl) and / or the dynamic pressure (P2) corresponding electrical measurement signal are connected.

3. Probe according to claim 1 or 2, characterized in that the first measuring opening (4 ') is provided on a surface, preferably on a flat surface of a flow guide element (8), for example a plate-like flow guide element.

4. Probe according to one of claims 1-3, characterized gekenn¬ characterized in that the first measuring opening (4 ') is formed by an open end of a pipe section or pipe section (2).

5. Probe according to one of claims 1-4, characterized gekenn¬ characterized in that the second measuring opening (9) is formed by an opening in a wall of a pipe section (3).

6. Probe according to one of claims 1-5, characterized by an inner pipe section (2) which forms the first measuring opening (4 ') and the first channel with one end, and by a second, the first pipe section (2) on at least a partial length concentrically and at a distance enclosing pipe section (3), on which the second measuring opening (9) is provided and which delimits an annular second channel (5) surrounding the first pipe section (2) to the outside.

7. Probe according to one of claims 1-6, characterized by its design as an air flow meter or air mass meter for an internal combustion engine, preferably together with a pressure cell.

8. Probe according to one of claims 1-7, characterized gekenn¬ characterized in that the first and second channels (4, 5) are each connected to a chamber or to a partial space of a differential pressure cell (20, 30).

9. Probe according to one of claims 1-8, characterized gekenn¬ characterized in that it together with a pressure cell (20, 30) one for several cylinders (12) of an internal combustion engine The machine (11) forms a common air mass meter, which supplies a signal (54), which reflects the individual intake strokes of the internal combustion engine and changes in amplitude over time, to control electronics (53) which, based on the curve or amplitude of the signal assigned to the respective cylinder (12) (54) controls the cylinders or their fuel supply individually.

10. A probe according to claim 9, characterized in that the control electronics (53) a the time course of the signal (54) of the air mass meter or the load cell of the rotational position or the working cycle or cycle of the engine (11) associated auxiliary signal (56) is supplied .

11. Load cell, in particular for use with a probe according to any one of claims 1-10, for measuring the pressure of a flow medium, in particular for measuring the pressure of gases and / or air, with a housing (31), with at least one in the housing (31) provided diaphragm (32), which delimits at least one partial space (33, 34) formed in the housing (31) and which can be acted upon by the flow medium pressure, and with a measuring device (35, 37) for generating at least one of its size Deflection of the membrane (32) -dependent electrical measurement signal, characterized in that the measurement device is formed by a mirror element (35) and by an optoelectric unit (37) which has at least one light path with at least one light transmitter for generating a light on a mirror surface ( 36) of the mirror element (35) incident light flux (41) and with at least one light receiver (40) for receiving one of the mirror surface (36) reflected Luminous flux that the mirror element (35) on the membrane (32) or on the housing (31) and the optoelectric unit (37) on the housing or on the membrane (32) are provided that the mirror surface (36) is concave, and that the light transmitter (39) and / or the light receiver (40) are adjusted so that the amount of light incident on the light receiver (40) is a function of the deflection of the membrane (32).

12. Load cell according to claim 11, characterized in that the mirror element (35) is arranged so that the optical axis of the mirror surface (36) and that of the light path is transverse or perpendicular to the movement of the membrane (32).

13. Pressure sensor according to claim 11 or 12, characterized gekenn¬ characterized in that the optoelectric unit (37) is arranged so that the emitted by the light transmitter (39) and the from the mirror surface (36) reflected light flux (41, 42nd ) radially to the axis (A) of the movement of the membrane (32).

14. Load cell according to one of claims 11 - 13, characterized in that the at least one mirror element (35) and the optoelectric unit (37) in a housing (31) formed and delimited by the membrane (32) subspace (33) is.

15. Pressure sensor according to claim 14, characterized in that the mirror element (35) and the optoelectric unit (37) containing sub-space (33) is a sub-space acted upon by the flow medium pressure.

16. Pressure sensor according to one of claims 11 - 15, characterized in that the mirror surface (36) has the concave curvature at least in one sectional plane, and that the at least one light transmitter (39) and the at least one light receiver (40) with their optical axis define a further plane (M ') which is perpendicular or approximately perpendicular to the said cutting plane.

17. Pressure sensor according to claim 16, characterized in that the mirror surface (36) forms a central plane (M), and in that of the optical axes of the light transmitter

(39) and the light receiver (40) defined plane (M ') of the optoelectric unit (37) is at the same time the central plane (M) of the mirror surface (36), or is arranged parallel or approximately parallel to this central plane.

18. Load cell according to one of claims 11 - 17, characterized in that the light beam emerging from the light transmitter (39) and reflected on the mirror surface (36) is focused such that the reflected light beam incident on the light receiver (40) in a first position of the membrane (32) and the mirror element (35) completely or almost completely strikes the light receiver (40) and one of the openings

(43) of the light receiver (40) has a corresponding or almost corresponding cross section (44), and that in a second position of the membrane (32) and the mirror element (35) the cross section of the light receiver

(40) impinging reflected Lichtstron.es (42) is larger than the opening of the light receiver (40).

19. Pressure sensor according to one of claims 11 - 18, characterized in that in the second position of the membrane (32) only a part of the opening (43) of the light receiver (40) is hit by the reflected light flux (42).

20. Load cell according to one of claims 11 - 19, characterized in that the mirror surface (36) is curved only in one plane.

21. Pressure cell according to one of claims 11 - 20, characterized in that the mirror surface (36) is curved in two planes.

22. Pressure sensor according to one of claims 21-21, characterized by its design as a differential pressure sensor.

23. Device for measuring the amount or mass of a medium flowing through a space or flow channel (13), in particular gas and / or air, using at least one pressure sensor according to one of claims 11 to 22, characterized by probe elements for detecting the static as well as dynamic pressure in the flow channel, a channel (4, 5) provided with a measuring opening (4 ', 9) of each probe element being connected to a partial space (33, 34) of a pressure cell (30) the optoelectric unit (37) of the at least one pressure transducer (30) is supplied with a measurement signal of an electrical circuit arrangement (48) which delivers an electrical signal corresponding to the quantity or the mass of the flow medium flowing through the flow channel from this measurement signal, taking into account the temperature of the flow medium and / or the ambient pressure.

24. The device according to claim 23, characterized by a temperature sensor (49) and / or by an additional pressure sensor (50) for measuring the temperature of the flow medium and the ambient pressure.

25. The device according to claim 24, characterized in that the temperature sensor (49) controls the intensity of the light emitted by the light transmitter (39) and / or the amplitude of the measurement signal supplied by the light receiver (40).

26. Device according to one of claims 23 - 25, characterized in that the intensity of the light emitted by the light transmitter (39) and / or the amplitude of the measurement signal generated by the light receiver (40) is controlled by the additional pressure sensor (50) becomes.

27. The device according to one of claims 23 - 26, characterized in that the probe elements for the static and dynamic pressure or their channels (4, 5) each with a partial space (33, 34) of a common

Differential pressure cell (30) are connected.

28. Device according to one of claims 23 - 27, characterized in that the probe elements for the static and dynamic pressure are formed by a single probe (1).

29. The device according to any one of claims 23 - 28, characterized in that a plurality of pressure transducers (30) for separate detection of the flow quantity or mass of the flow medium in several channels (13) are connected to a common Schaltungsein¬ device (48).

30. The device according to claim 29, characterized in that the circuit (48) for all channels (13) has a common additional temperature sensor (49) and / or pressure sensor (50).

31. The device according to any one of claims 23 - 30, gekenn¬ characterized by its training as an air mass meter for internal combustion engines.

32. Device according to one of claims 23 - 32, characterized in that it is a common for several cylinders (12) of an internal combustion engine (11) Luftmassen¬, and that the signal from the pressure cell (30) or the optoelectric unit (37 ) or a signal (54), which changes over time and is derived from this taking into account the temperature of the flow medium and / or the ambient pressure, is fed to control electronics (53) which, according to the amplitude of the signal (54), the cylinders (12) or the fuel supply controls these cylinders, specifically each cylinder (12) depending on the associated amplitude of the time-changing signal (54).

33. Apparatus according to claim 32, characterized in that the control electronics (53) from the engine or its ignition derived auxiliary signal (56) is supplied, and always when the engine has run through a predetermined cycle.

34. Internal combustion engine with at least one probe (1) arranged in an intake duct (13) according to one of claims 1-10.

35. Internal combustion engine according to claim 34, characterized in that at least one probe is provided in each intake duct (13) of each cylinder (12) of the internal combustion engine.

36. Internal combustion engine according to claim 35, characterized gekenn¬ characterized in that the cylinders (12) via the probes (1) are individually controlled.

37. Internal combustion engine according to any one of claims 34 - 36, characterized in that the signal of each probe or each pressure sensor associated with a probe (20, 30) is fed to control electronics (15) which, based on these signals, are used for each intake duct (13) generates a signal corresponding to the amount of air or air mass, preferably taking into account further parameters such as air temperature and / or ambient pressure.

38. Internal combustion engine according to one of claims 34 - 37, characterized in that the probe (1) with the pressure cell (20, 30) forms a common mass flow meter for a plurality of cylinders (12) of the engine (11), which measures the individual intake strokes of the Signal (54) which reflects the internal combustion engine and changes in amplitude over time, is supplied to control electronics (53) which individually control the cylinders or their fuel supply from the curve or amplitude of the signal (54) associated with the respective cylinder.

39. Internal combustion engine according to claim 38, characterized gekenn¬ characterized in that the control electronics (53) one the time The course of the signal (54) of the air mass meter or the pressure transducer of the rotary position or the work cycle or cycle of the motor (11) is supplied with an auxiliary signal (56).

40. Internal combustion engine, characterized by at least one probe (1) provided for the combustion gases in a channel (57) for measuring the pressure and / or the pressure changes and / or for measuring the flow rate and / or changes in the flow rate in this channel ( 57).

41. Internal combustion engine according to claim 40, characterized gekenn¬ characterized in that the probe is one according to one of claims 1-12.

42. Internal combustion engine according to one of the preceding claims, characterized in that the probe (1) is connected to a pressure load cell (58), preferably to a differential pressure load cell.

43. Internal combustion engine according to claim 42, characterized gekenn¬ characterized in that the pressure cell is a differential pressure load cell according to any one of claims 11-22.