JPH0125403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fluid flow meters, particularly fluid flow meters such as fuel consumption meters for motor vehicles, where an accurate indication of instantaneous flow velocity and/or flow rate over a predetermined period of time is important. The present invention also relates to a liquid flow meter suitable for measuring liquids.

In the field of fluid flow meters, many proposals have been made in the patent literature. A rotor is adapted to be caused to rotate about its shaft by fluid flowing axially therealong, and means are provided for observing rotor rotation and converting this into a signal representative of flow velocity. Two major systems can be distinguished in fluid anemometers that use journalled rotors in the fluid passages.
There are therefore flow meters for liquid metering devices, such as beverage dispensers, which must be able to flow equal portions of a relatively large amount of liquid, such as a soft drink, in a predetermined relatively short period of time. In order not to disturb this liquid flow unnecessarily, a rotor is used which has a helical shape such that the liquid flowing axially through all the passage openings impinges on the rotor at a relatively small angle, for example 20°. There is no problem of a linear relationship between rotational speed and liquid velocity within a wide range, due in part to the slippage that cannot be avoided under these circumstances.
However, this is not a disadvantage in beverage dispensers that only need to repeatedly dispense a predetermined full amount over a predetermined short period of time.

Examples of fundamentally different systems are described in US Pat. Nos. 3,240,063 and 3,922,525.
These use a rotor with blades that extend radially in a plane containing the rotor axis, and the rotor is rotated so that the rotor axes intersect as perpendicularly as possible, so that optimum action is exerted on the rotor blades. Upstream of the fluid flow is diverted from its initial axial direction into a helical motion. In the flowmeter described in U.S. Pat. No. 3,240,063, the liquid diverting member is designed as an insert filling the fluid passage, the insert having a helical passage around its circumference, whereby the liquid flow is directed in a helical manner. Furthermore, the liquid passage is restricted, thereby creating an acceleration that achieves a relatively large number of rotor revolutions per volume of liquid flowing through the device. In combination with sensing means that transform rotor rotation into pulses and translate this into flow velocity values, such an increase in flow velocity is favorable for the accuracy of the measurements.

However, it is found that highly inaccurate vacuum measurements at the inlet stub of the engine, which indirectly derive the fuel consumption from it, are still very often applied in practice, in particular for measuring the fuel consumption of vehicle motors. The reason for this is
It has been difficult to realize a meter of the type described in US Pat. No. 3,240,063 that is inexpensive, highly reliable, and gives accurate indications over a wide range. In this context, a rotor that has to rotate about its axial centerline in an axial liquid flow is affected by the axial thrust of the liquid flow in the sense that the rotor is forced against its downstream bearings. , it must be taken into account that the bearing friction increases and the speed of the rotor, ie the number of revolutions per unit time, no longer represents the amount of liquid passing through it. In the meter described in US Pat. No. 3,240,063, this effect is taken into account by using double ball bearings for the rotor. Furthermore, in Swiss Patent Specification No. 474050, for the purpose of preventing axial liquid thrust, a rotor directs a portion of the axial flow in a radial direction relative to a liquid vortex held near its outer circumference. A structure is described that is adapted to be returned countercurrently along the outside of the rotor in a journal-supported manner. The reason why consumption meters described in patent literature have hitherto been rarely or never used is that they are complex and therefore expensive;
Furthermore, it can be mentioned that they are prone to breakdowns, cannot be made to small dimensions and/or no longer give accurate indications in the absence of large fluctuations in flow rate. Especially in the low speed range, the effect of ball bearing friction is considerable.
The vortex on the outer circumference of the rotor then ceases to function.

The present invention provides current meters that not only provide excellent satisfaction as shown by testing, but can also be made cheaply enough to allow them to be manufactured in disposable form. This is important, for example, to ensure sterile conditions in medical injection devices.

Starting from the state of the art described in U.S. Pat. a liquid directing member in the form of an insert that satisfies the flow path; a rotor having an axis of rotation oriented in the axial direction of the passageway and journalled downstream of the insert; comprising blade members extending at spaced positions;
A fluid flow meter further comprising means for sensing rotation of the rotor and converting these into signals representative of fluid flow velocity, wherein the rotor has a central axis, the upstream end of the central axis being at the downstream end face of the insert. journalled in a cavity provided for that purpose, the downstream end of which is journalled in a similar cavity in a counterbearing, which counterbearing includes the cavity and is connected via a radial seat member. a central portion connected to a wall of the passageway, the rotor being journalled with limited axial clearance;

Such a flow meter satisfies a number of requirements. The counter bearing can be manufactured together with the housing and with the rotor and insert in one injection molding process, so that the flow meter is assembled from only three parts, excluding the rotation sensing means. The assembly moves the rotor into the housing until the downstream shaft end is received within the cavity of the counterbearing and the insert is then held in place in a self-gripping manner and axially contacted by a stop shoulder formed within the housing. It is only necessary to lower the During operation, the liquid moves helically in the rotor zone and impinges against the radially extending seat member of the counterbearing, with the majority of the liquid being guided directly axially in the downstream direction; At the same time, the counterthrust causes the rotor to remain axially floating. If the meter, and therefore the rotor, have small dimensions, and at least the rotor is made of synthetic plastic material, its mass in the liquid is very light, as a result of which bearing friction is negligible.

The meter according to the invention may therefore be a light structure made of synthetic plastic material, the length of which is approximately 40 mm, the diameter of the passages ranging from 4.5 to 5 mm, and the diameter of the largest rotor being 2.3 mm. and
The insert may have an axial length of 3 mm, the rotor space may have an axial length of 3 mm, the downstream counterbearing may be 2 mm, and its weight may not exceed 10 g. The meter is therefore of such length that it can be installed in the combustion line, allowing it to operate without further support or suspension. Furthermore, the meter is not sensitive to engine vibrations and its angular position is of no importance. In this context, the rotor is about 15 mg, so even in liquid the position of the entire meter does not affect the bearing friction.

Due to the size of these small rotors and the light weight within the liquid, the meter is set directly on the movement of even the slightest fluid flow.
In practice, even flow rates of 2 liters/hour are accurately measured.

Experiments have shown that the liquid thrust effect in motor bearings is caused by inserts with two helical circumferential grooves, each at an acute angle to the axis, extending at about 180°, and mutually extending. An improvement of the invention by providing an insert starting and terminating diametrically opposite the fluid passageway, and a counterbearing formed as a flat strip extending laterally through the fluid passageway. Therefore, it can move in a wide range of flow velocities.

As mentioned above, it is desirable to measure as many pulses of fluid flow per unit as possible. When using rotation sensing means based on light beam blocking operation, which has advantages over magnetically actuated structures in which the rotor rotation does not have to overcome the strength of the magnetic field, as many light beams as possible per rotation of the rotor are used. It is desirable to sense the interruption of the Theoretically,
This only requires increasing the number of rotor blades. In practice, however, this results in inaccuracies, especially when the total rotor is of small diameter, partly as a result of the refraction of the light beam of the meter, the material of the housing and the fluid flowing through the meter.
becomes inaccurate. In U.S. Patent No. 4012958,
In this regard, it has been proposed to form part of the wall of the housing like a converging lens in order to focus the light rays coming from the light source so that the small blades protruding from the core of the rotor are visible. ing.

According to the present invention, the generation of pulses by interrupting the light beam multiple times per rotation of the rotor can be easily performed by crossing or crossing the light beam with the rotor axis over a short distance, and It is possible to create a space for the rotor near the axis of the rotor. When the rotor rotates, therefore, the rotor parts which are placed in radially offset relation to the axis always intercept the light beam in a simple manner.

Therefore, according to the invention, the rotor may consist of a flat, rectangular body with a stud shaft extending at both ends of the shaft and having a central hole therein through which the light beam passes.

Having a cavity inside the rotor body poses no danger at all. In fact, any gas bubbles that may be present in the fluid flow are forced by centrifugal force towards the center of the passage and into the rotor body. Bubbles cause light beam refraction such that the meter no longer gives an accurate reading, or no reading at all.

In order to minimize the chance of air bubbles getting stuck in the central rotor hole, according to the invention, the central hole may be polygonal.

Of course, it is possible to prevent the inflow of air bubbles into the meter by suitable means, such as an air vent downstream of the meter, but according to a feature of the invention, the hollow space present in the rotor, Leaving it open at the downstream end is cheaper and allows the bubbles to be carried downstream, and practical experiments have shown that this is actually a good idea.

In a preferred embodiment of the invention, the rotor provides a body extending transversely to a central axis, and circumferentially spaced cantilever rod elements are provided in spaced relation to said axis. , extending in the downstream direction.

However, the presence of a void in the rotor makes relevant the fact that at a given moment no fluid flows through the meter and the meter must sense this. According to the invention, this was achieved by maximizing the radial dimensions of the rotor and making them slightly smaller than the corresponding dimensions of the liquid flow channels. Therefore, even when there is no fluid in the center of the flow path, the rotor immediately stops due to the friction of the liquid layer that always exists on the wall surface of the flow path.

This characteristic of the meter according to the invention, together with a very low rotor weight and negligibly low bearing friction on the rotor shaft, ensures a high sensitivity, which is necessary for accurate total measurements, and this latter is necessary for accurate total measurements. is possible only when the rotor starts rotating as soon as the fluid flows along the meter and stops as soon as the fluid flow stops.

According to the invention, it is also possible to use infrared devices known per se. The device uses long wavelengths of infrared radiation that cause relatively little reflection within the material.
Therefore, there is the advantage that a wide range of materials can be selected for the housing.

The flow meter according to the invention made according to the specifications hitherto described has a flow rate of 2 liters per hour and 80 liters per hour.
It has become clear that various flow rates between bottles can be measured accurately and instantly. rotor speed
Between 5000rpm and 6000rpm, it is possible to measure the gas oil flow rate with a deviation of 1.5% or less. Furthermore, the flow meter according to the invention is less susceptible to blockage so that any dust entering the meter does not obstruct its flow path and prevents the flow path from being carried away.

Overall, it is not difficult to make accurate and linear measurements within a narrow predetermined range of flow rates, but until now, it has been difficult to make accurate and linear measurements without the use of large and complex equipment. It was not possible to accurately measure the flow rate. The present invention is the first to provide a flow meter of simple and inexpensive construction that achieves this objective.

Referring to the drawings, and in particular to FIG. 1, the fluid flow meter of the present invention is installed in a fuel line 1 whose direction of flow is indicated by the arrow. The current meter has a cylindrical housing 2 made of, for example, a transparent synthetic plastic material. A rectangular rotor 3 having a central window 4 and shaft stubs 5 and 6 in the housing 2 is mounted between a single-threaded or multi-threaded worm 7 and a plate-shaped counterbearing 8 extending across a central opening in the housing 2. Supported by journal. The shaft stubs 5 and 6 of the rotor 3 are freely rotatably housed in bearing cavities in the worm 7 and counterbearing plate 8.

The flow of oil in line 1 is forced by the worm 7 into a relatively narrow channel defined by the worm winding and the housing 2, or into multiple channels if the worm is multi-threaded. . The exit of the worm channel in the rotor 3 is surrounded by the rotor axis at an angle as close as possible to 90°, so that the rotor 3
In the space 9 in which the rotor rotates, the fluid flows as diametrically as possible and impinges on the rotor substantially at right angles. The plate-shaped counter-bearing 8 forms a resistance in the oil line 1 and the rotor 3 is not forced into the combined bearing cavity by the shaft stub 6, but in the axial direction the bearing plate 8 and the worm 7 face each other. It imparts some kind of thrust in the oil flow which gives the desired result of suspension between the bearing cavities.

The housing 2 has diametrically opposed signal sources and receivers, such as an infrared radiation source 10 and a receiver 11 as schematically shown. The light beam emitted by the transmitter 10 passes through the rotor window 4 and is interrupted periodically by the rotation of the rotor.
The receiver 11 thus receives the light pulses which are further converted in known manner into a signal representative of the fluid flow rate. The rotor window 4 is preferably rectangular, thereby preventing air bubbles from clinging to the window that would interfere with the signal transmitted by the transmitter 10.

The fluid flow meter of the present invention shuts off the oil line,
In a simple manner, by sliding the ends of the tubes onto the current meter housing 2 and securing them, for example by clamping means, and connecting the necessary electrical and other terminals to a reading or recording device. can be installed in the oil line 1. Such oil flow meters can be made inexpensively and provide accurate readings of the instantaneous actual oil flow rate to the engine carburetor.

When made of synthetic plastic material, the rotor 3 weighs only around 15 mg, thus reducing its mass moment of inertia, allowing the rotor to respond instantaneously to fluctuations in flow rate, while shifting is negligible. No friction occurs and bearing friction is also minimized. Partly as a result of the rotor's particular mounting method, the current meter becomes less sensitive to vibration and position changes.

2a and 2b show different configurations of the rotor and different arrangements of the signal transmitter 10 and receiver 11. FIG. In the example of FIG. 2a, the rotor is closed, ie there is no central opening 4, and the signal emitter and receiver are arranged eccentrically. Further, FIG. 2b shows an example in which the signal device is provided eccentrically, but since the rotor 3b has a large central opening 4b, four pulses are generated per rotation of the rotor.

In the example of FIGS. 3 and 4, the current meter also has a housing 2 located in the oil line. The housing 2 can be made by a single injection molding means to have outer recesses 12 and 13 for accommodating the infrared transmitter 10 and the receiver 11 and a counter-bearing plate 8. Inside the housing 2 a stop shoulder 14 is formed for a liquid director in the form of an insert 15 with two helical peripheral channels 16 and 17, channel 1
6 and 17 each extend approximately 180° and begin and end at diametrically opposed points. Each terminal is offset by 90° relative to the counter bearing 8.

At the opposing end faces of the insert 15 and the counter bearing 8, each bearing recess 18
and 19 journally support the shaft 20 of the rotor 21, and the entire length of the rotor shaft 20 is the recess 18.
and 19, and thus the rotor 21 is journalled with a gap in the axial direction.

The rotor 21 includes a body 22 extending transversely to the axis 20, from which a cantilevered bar member 23 extends downstream adjacent the inner wall of the housing 2.

The liquid streams coming from the helical channels 16 and 17 impinge on these members 23 at substantially right angles, causing the rotor to rotate, and the members 23 cause a light beam 24 (see FIG. 4) to travel closely along the rotor axis 20.
cut off. The rotor 21 has an open shape so that no air bubbles are retained. The rotor stops immediately when the liquid flow through the current meter is cut off.

Assembly of the current meter consists of inserting the rotor 21 until the downstream end of the shaft 21 is received in the bearing cavity 19, guiding the insert 15 up to the stop 14, and adapting the transmitter 10 and receiver 11 for the purpose. This is done by providing in the recesses 12 and 13 so as to.

[Brief explanation of drawings]

FIG. 1 depicts a fluid flow meter of one embodiment of the invention particularly suitable for use in measuring flow velocity in a fuel line, shown partially in axial cross-section and in side view. Figures 2a and 2b are simplified elevational views of other embodiments of the rotor. FIG. 3 is a simplified perspective view, partially cut away, of a preferred embodiment of the fluid flow meter of the present invention. 4 is an end view of the rotor of the preferred embodiment of FIG. 3; FIG. 2...Housing, 3...Rotor, 4...Center hole, 5 and 6...Shaft stub, 8...Counter bearing, 10...Infrared transmitter, 11...Infrared receiver.

Claims (1)

Claims: 1. a housing disposed within a conduit having an axial passageway; a fluid directing member in the form of an insert fitting within the passageway having at least one helical channel around the periphery; a rotor journalled downstream of the insert having an axis of rotation aligned with the axis of the passageway and having vane members extending parallel to and radially spaced apart from the axis of rotation; means for detecting the rotational speed of the rotor to generate a signal indicative of the fluid flow rate, the rotor having central shaft means, the upstream end of the central shaft means being located at the first end of the downstream end face of the insert. in a fluid flow form, the downstream end of the central shaft means being located in a second similar hole centrally located in the member, wherein the end of the central shaft means is disposed within the restriction; journalled within the first and second holes, respectively, with an axial clearance such that the member disposed within the second hole is disposed through the radial seat member; a counter bearing connected to the wall of the passageway, the means for detecting the rotational speed of the rotor comprising a radiation detector and means for providing a beam of optical or infrared radiation, the beam being connected to the wall of the rotor; intersecting or passing through the axis of the rotor at a small distance, the rotor comprising a flat rectangular body, the central shaft means having a stub shaft extending at each end thereof, the rectangular body a portion of the rotor forming the vane member and having a central aperture through which the beam passes, the portion of the rotor being spaced radially apart relative to the axis as the rotor rotates; A fluid anemometer, characterized in that the beam is periodically interrupted by the beam. 2. The fluid flow meter according to claim 1, wherein the central opening is polygonal. 3. A fluid flow meter as claimed in claim 1 or claim 2, wherein the largest diametrical dimension of the rotor is only slightly smaller than the corresponding diameter of the passageway. 4. The fluid flow meter according to any one of claims 1 to 3, wherein the means for detecting the rotational speed of the rotor includes an infrared device. 5 a housing disposed within a conduit having an axial passage; a fluid directing member in the form of an insert fitted within the passage having at least one helical channel therearound; and a fluid directing member in the form of an insert fitted within the passage; a rotor journalled downstream of the insert, the rotor having an axis of rotation and having vane members extending parallel to and radially spaced apart from the axis of rotation; and detecting the rotational speed of the rotor. means for generating a signal indicative of fluid flow velocity, the rotor having a central axis, the upstream end of the central axis being disposed within the first hole in the downstream end surface of the insert; In a fluid flow meter in which the downstream end of the central axis is disposed within a similar second hole centrally located in the member, the central axis has a limited axial clearance to support its support. journalled within the bore, the member in which the second bore is disposed is a counter bearing connected to the wall of the passageway via a radial seat member, and the rotor is substantially parallel to the central axis; a rotor body extending laterally across the blade member, the blade member being spaced apart from the central axis;
comprising circumferentially spaced cantilevered bar elements extending downstream from the rotor body, the means for detecting the rotational speed of the rotor comprising a radiation detector and means for providing a beam of optical or infrared radiation; the beam intersects or passes through the axis of the rotor at a small distance; the rotor has a central hollow space through which the beam passes; A fluid flow meter having an opening at a downstream end of a rotor such that the cantilevered bar element periodically interrupts the beam as the rotor rotates. 6 the insert has two circumferential channels, each about approximately
extending at an acute angle of 180° and beginning and ending in mutually perpendicularly opposite directions, the counterbearing being formed as a flat strip extending laterally through the passageway; A fluid flow meter according to claim 5. 7. A fluid flow meter as claimed in claim 5 or claim 6, wherein the largest diametrical dimension of the rotor is only slightly smaller than the corresponding diameter of the passageway. 8. The fluid flow meter according to any one of claims 5 to 7, wherein the means for detecting the rotational speed of the rotor includes an infrared device. 9 the housing has a stop shoulder for positioning the fluid directing insert within the housing, the counterbearing being disposed downstream of the insert and in the form of a plate extending laterally through the passage; and is arranged substantially transversely to a line connecting the end of the channel provided in the insert, and the cantilevered rod element has a circular or semicircular cross section. The fluid flow meter according to any one of items 5 to 8.