EP0651965B1 - Vacuum cleaner flow rate regulating sensor - Google Patents

Description

The present invention relates to the operation of a dust vacuum cleaner, and more particularly a control and / or regulation of air flow and vacuum automatic. The present invention relates in particular to using the operation of a vacuum cleaner or more generally any household appliance using a air flow during operation.

It is already known in the prior art, in particular in GB-2016910 to use in combination, a limitation of depression created by the vacuum cleaner and a flow control means, which consists on the one hand pressure sensors and on the other hand a cover arranged on the air outlet of the electric motor causing a fan. The cover thus achieves resistance to air flow leaving the engine. The arrangement of the cover on engine helps reduce air expulsion area between the motor and the cover. Such a reduction achieves a pressure drop in the air flow, corresponding to a pressure variation, which is measured by a pressure sensor pressure. The air expelled by the engine and channeled by the cover arranged on said motor is then expelled from the frame from the vacuum cleaner through an opening. So it creates a pressure difference between an area upstream of the surface reduced expulsion and the internal volume of the the vacuum cleaner, which is connected through the opening with ambient pressure. The pressure difference between these two zones and more precisely the pressure drop, allows to know and more particularly to limit the air flow from the vacuum cleaner. Such a conception, associated using pressure sensors actually allows to obtain a regulation of the operation of the vacuum cleaner but nevertheless has a number of drawbacks. The major drawback is the shape of the cover used to achieve a pressure drop in the air flow sucked as well as in the positioning of said cover. In effect, to keep a sufficient pressure drop in the air flow exiting the engine the expulsion surface device should be reduced significantly. A such reduction generates an air flow velocity more important and therefore increases the noise level of the vacuum cleaner. The use of a soundproof cover is therefore essential. Another disadvantage of the vacuum cleaner as described in the prior art above, lies in the imprecision of measuring a differential pressure. Indeed after a certain time of operation, engine fouling on the one hand and fouling or clogging of the opening greatly alters vacuum cleaner flow control. The sensors pressure are lured and no longer respond to air flow actual and actual flow of aspirated air. Another downside of the vacuum cleaner described in application GB-2016910 resides in large dimensions of the motor-cover assembly which must be housed in a compartment inside the frame of said vacuum cleaner.

We also know the document US-A-4,733,431 in which a vacuum cleaner is provided with different differential pressure tap means to give the user an indication on the correct installation or on the absence of the bag recuperator inside the vacuum cleaner. Differential pressure taps are located for example between the engine compartment and the compartment intended for receive the dust collection bag or between the suction inlet through which the air flow and the compartment intended to receive the dust collection bag. So depending on the correct or wrong arrangement or the absence of the bag inside of the vacuum cleaner, the user is informed by means of a light signal and the motor may be cut for safety. Pressure taps differential described also make it possible to detect an excessive clogging of the dust collection bag.

Another object of the invention lies in the implementation work of this optimization by extremely means simple and inexpensive, furthermore carrying out several functions.

The objects of the present invention are achieved at using a vacuum cleaner with an electric motor controlling a fan, to create an internal depression and a suction air flow to transport the dust sucked into a dust collector as well as means engine speed control and / or regulation electric, connected to a pressure measuring device internal and at least one pressure measuring device differential air flow, said control means being suitable according to the result of the depression measurements and differential pressure to control and / or regulate in the speed of the electric motor to maintain below limit values, vacuum and flow rate air, characterized in that the device for measuring the differential pressure has at least two points of measurement mounted in the air flow on either side of a piece with a calibrated opening to create a loss dump.

Modifications to the vacuum cleaner according to claim 1 are specified in dependent claims 2 to 11.

• la figure 1 représente une vue d'ensemble en coupe de l'aspirateur conforme à l'invention,
• la figure 2 représente une vue de face de la pièce annulaire conforme à l'invention,
• la figure 3 représente une vue en coupe selon la direction A-A de la pièce annulaire conforme à l'invention,
• la figure 4 représente une courbe schématisant le fonctionnement de l'aspirateur conforme à l'invention,
• la figure 5 représente un exemple de montage des organes de mesure de dépression et de pression différentielle dans un aspirateur conforme à l'invention.

The characteristics and advantages of the invention will emerge more clearly on reading the description given below by way of nonlimiting examples, with reference to the appended drawings in which:

• FIG. 1 represents an overall sectional view of the vacuum cleaner according to the invention,
• FIG. 2 represents a front view of the annular part in accordance with the invention,
• FIG. 3 represents a sectional view in the direction AA of the annular part according to the invention,
• FIG. 4 represents a curve diagramming the operation of the vacuum cleaner according to the invention,
• FIG. 5 shows an example of mounting of the vacuum and differential pressure measurement members in a vacuum cleaner according to the invention.

The vacuum cleaner 1 according to the invention and shown in Figure 1, comprises a frame 1a in which are formed a compartment 2, a measurement chamber 6 and a collector 4. The electric motor 2a driving the fan 2b is housed in compartment 2, which is in communication with Ambiant air. Compartment 2 also communicates with the measuring chamber 6 which leads to the collector 4. The manifold 4 is connected by an orifice 5b to a pipe 5 on which is arranged a nozzle (not shown in the figures) and intended to collect the dust sucked by the vacuum cleaner. Advantageously, the collector 4 contains a bag 3 allowing collect the dust collected and keep it in this last. The bag 3 is preferably made so as to be permeable to air flow 20 while trapping the dust sucked in and conveyed by said air flow 20, through the pipe 5, into the bag 3. The measuring chamber 6 providing the interface between compartment 2 and the manifold 4 comprises a part 10 provided with an opening 12 calibrated, to create a pressure drop in the air flow 20. Exhibit 10 shown in Figures 1, 2 and 3 shows an annular shape to partially obstruct the flow of the air flow 20. The latter therefore flows from the manifold 4 towards compartment 2 where the fan 2b is housed, in passing through the measurement chamber 6 and more particularly through the calibrated opening 12 presented by the part 10. The flow air 20 thus experiences a pressure drop when it passes through the measurement chamber 6. Advantageously, the part 10 has in a plane perpendicular to the direction of flow of the air flow 20, a solid disc 12a pierced with an opening 12 of preferably circular and calibrated. Exhibit 10 presents also a peripheral rim 14 and lugs of positioning 15 intended to position, stably, said part 10 inside the measurement chamber 6, by all known means. In addition, part 10 also comprises a tube 13 drilled and molded for example, whose drilling extends over the entire thickness of said piece 10, and intended to position a pressure sensor connected to a pressure switch for example. So room 10 is arranged in a room 6 measured between the dust collector 4 and the fan 2b, the suction air flow 20 circulating from manifold 4 to fan 2b.

The vacuum cleaner according to the invention and shown in Figure 1 also includes a member for measuring a internal depression U3 produced by the fan, said member being arranged in the collector 4 in the vicinity of the orifice 5b for entering the air flow 20 coming from the pipe 5.

The vacuum cleaner, according to the invention and shown in Figure 1, also includes a pressure measurement member differential U2 of the air flow 20, arranged in the measure 6. Preferably the measuring organs of depression U3 and differential pressure U2 are consisting of membrane pressure switches. U2 and U3 have two inputs separated by a membrane, which actuates a switch for a difference of determined pressure on either side of said membrane. The measurement points 7, 7a and 7b are for example constituted connecting tubes, one end of which opens into the atmosphere of a first pressurized zone, the other leading to a pressure switch input. The connecting tube can also be split and feed a second pressure switch. The second input of the pressure switch is either connected directly or via a tube connection to atmospheric pressure or to a pressurized area separate. Thus the vacuum measurement unit U3 allows to detect through a measuring point 7 a pressure drop inside manifold 4 relative to at atmospheric pressure. In addition, the measuring device differential pressure U2 allows through measuring points 7a and 7b to detect a pressure drop between upstream and downstream of room 10, housed or fixed at inside the measuring chamber 6. By measuring point 7, 7a or 7b, it is necessary to understand a means linking the diaphragm of a pressure switch and more particularly one side of said membrane with the atmosphere in which a pressure must be measured. This can be advantageously achieved by through the drilled tube 13 molded, for example, in the room structure 10.

The means of control and / or regulation include electrical contacts connected to an electrical circuit or electronic to vary the voltage electric motor supply. These electrical contacts are preferably made directly by the pressure switches U3 and U2 used in vacuum measurement devices U3 and differential pressure U2. So the contacts electric actuated by pressure switches allow partially or completely reduce engine power electric by any known means and in particular by a short circuit made at the terminals of an electrical resistance, which partially or fully performs the feeding electric of said electric motor. Preferably the electrical contacts actuated by pressure switches are connected in parallel in the electrical circuit or electric motor supply electronics. Of this way, the speed of the electric motor depends on the measurement made by the vacuum measurement unit U3 and the unit differential pressure measurement U2. Engine speed electric therefore has a variation either depending on the vacuum produced inside the manifold 4, ie function of the air flow flowing through the measure 6.

Advantageously, the pressure switches U3 and U2 measuring and / or controlling depression and pressure respectively differential are tared on a value included between 130 and 150 millibars respectively and between 8 and 15 millibars, for calibrating the opening of the part 10 given annular, said pressure switches being intended to cut at least partially the power supply of the electric motor when the vacuum or differential pressure exceeds the taring value. A calibration of such a pressure switch is obtained by the use of a membrane having rigidity determined. Thus the pressure switch and in particular the membrane activates an electrical contact only when the difference in pressure between the two inputs of said pressure switch is higher than the setting value of said pressure switch. In addition for optimal operation of the vacuum cleaner according to the invention, the annular part 10 has a circular opening 12 with a diameter between 35 and 45 millimeters and preferably between 39 and 41 millimeters. A calibration of the opening 12 associated with a setting of the pressure switches corresponds to a power of optimal operation of the electric motor between 800 and 1400 Watts and preferably close to 1200 Watts.

The measurement point 7b is preferably located in the measuring chamber 6 downstream of the part 10 and the point of measure 7a is located in the collector 4 and preferably at the outside of the bag 3 positioned in said collector 4 and collecting dust. Measuring point 7a is located therefore upstream of the part 10. The measurement points 7, 7a and 7b consist essentially of inlet ports of connecting tubes connected to the inputs of the pressure switches.

According to a preferred embodiment of the vacuum cleaner according to the invention and shown diagrammatically in the figure 5, the latter comprises in association with the U3 pressure switches and U2 of the U3 vacuum measurement and differential pressure U2, a pressure switch U1 calibrated on a value between 50 and 70 millibars on the one hand and connected by its inputs at measurement points 7 and 7a to determine the filling rate of the collector 4. So when the rate filling the dust bag 3 and therefore the collector 4 reaches a certain level, a depression substantially equal to 60 millibars is manifested between measuring points 7 and 7a. The electrical contact of the pressure switch U1 can then reduce the engine speed and supply a seeing for example.

Thus, the vacuum cleaner comprises, in association with the organ of vacuum measurement U3 and the pressure measurement device differential U2, a second pressure measuring device differential U1 to determine the filling rate of the collector 4.

The pressure switch U2 has an input, which communicates with measuring point 7b via a connecting tube 8a and the other inlet of which communicates with the measurement point 7a by a tube 8b, said pressure switch U2 used to determine a differential pressure in the air flow 20 upstream and downstream of part 10, upper at a value between 8 and 15 millibars. The pressure switch U3 tared for example at 130 millibars has an entry in communication with atmospheric pressure and a second input connected to measuring point 7 via a connecting tube 9. The pressure switch U3 thus measures the vacuum produced inside the collector 4 and the pipe 5 suction.

According to a preferred operating mode of the vacuum cleaner according to the invention and shown diagrammatically in the figure 4, it is advantageous to limit the operation of said vacuum cleaner with maximum flow on the one hand and a vacuum maximum on the other hand. Figure 4 shows a curve C1 representing the depression H as a function of the flow rate Q for a constant supply voltage to the electric motor. For a minimum flow value corresponding to a vacuum H maximum, the electric power consumed by the motor electric is about 800 Watts while for a flow maximum and therefore for minimum depression, the electrical power consumed is approximately 1400 Watts, for an example of a given electric motor.

Via a vacuum cleaner conforming to the invention, it is easy to limit oneself to a portion F of optimal operation on curve C1. Indeed the pressure switch U2 reduces the speed of the electric motor when the differential pressure measurement exceeds a value between 8 and 15 millibars and preferably 13 millibars corresponding to a maximum flow Q2 of the air flow 20. Conversely when the flow rate of the air flow 20 decreases, that is to say that the vacuum H increases, the pressure switch U3 reduces the speed of the electric motor when said depression H exceeds a maximum value H2 between 130 and 150 millibars. The operation and therefore the automatic and permanent regulation of the vacuum cleaner to the invention are obtained between two points of extreme H1, Q1 and H2, Q2 operation. These latter correspond respectively to an electrical power consumed between 800 and 1400 Watts. Maintaining below limit values Q2 for flow, and H2 for depression, allows on the one hand not to exceed a certain noise level and on the other hand not to be confronted with phenomenon of sticking or sticking of the nozzle on the surface to be cleaned, while maintaining a flow of air Q drawn in important or sufficient for cleaning, said flow Q is between 23 and 28 liters per second and preferably equal to 25 liters per second, for the example of given achievement. So the operating points extremes defining the portion F of optimal functioning of the curve C1 are defined by a maximum flow rate Q2 equal to 28 liters per second, a minimum flow Q1 equal to 23 liters per second and a maximum depression H2, for the example of preferential realization of the vacuum cleaner in accordance with the invention.

In addition, the part 10 can easily be replaced by another part 10 having a different calibrated opening 12, so as to obtain a different differential pressure and therefore a separate optimum flow rate. It is clear that in order to adapt the vacuum level H to particular applications, one or the other of the pressure switches U2 or U3 can easily be replaced by other pressure switches calibrated differently. As such the relation between the flow Q and the differential pressure h for a fluid is given by the formula: Q = KD 2 .√h , where D represents the diameter of the opening 12, K representing a constant taking into account the characteristics of the fluid. According to another alternative embodiment of the vacuum cleaner according to the invention, the electric motor can be chosen from a different power range, which also has the consequence of modifying the optimal operation of the vacuum cleaner, which can be corrected by the choice of a different opening 12 for example.

The vacuum cleaner according to the invention therefore has several parameters for optimal operation said vacuum cleaner in all kinds of uses.

According to an alternative embodiment of the vacuum cleaner in accordance with the invention, the measurement point 7 is deleted and the input of the pressure switch U3 is connected to the measurement point 7a. In addition, the setting of the pressure switch U1 is raised to a value between 130 and 180 millibars and for example equal to 150 millibars, and one of its inputs is connected to the atmospheric pressure.

An advantage of the vacuum cleaner according to the invention lies in the permanent regulation of the operation said vacuum cleaner whatever the surface to be cleaned on which it is used. Indeed the engine speed depends information read or measured by pressure switches U1, U2 or U3 which also allow to operate the vacuum cleaner with optimal air flow and vacuum optimal on all kinds of surfaces to be cleaned.

Another advantage of the vacuum cleaner according to the invention lies in the positioning of part 10 in a room 6 located between the collector 4 and the compartment 2 containing the electric motor 2a. Such a positioning of the part 10, associated with the measurement points 7a and 7b linked to the two inputs of pressure switch U2 to measure the flow effective and actual of the vacuum cleaner independently of a possible clogging of filters or openings through which the aspirated air flow 20 passes. Such an assembly allows also to produce a sufficient pressure drop for measure the flow of air Q drawn in and not to alter significantly the sound insulation that can present the whole vacuum cleaner. In addition the noise reduction suction is obtained by limiting the air flow Q below a maximum value Q2, as well as by a limitation of depression below a maximum value of depression H2. Indeed the parasitic or annoying noise comes basically the speed of the air flowing in the vacuum cleaner, the morphology of the path of said passage air flow 20 as well as the speed of the electric motor 2a. This latter increases significantly when flow increases or when depression increases. These phenomena are basically happen when the operating point no longer in the F portion of the curve C1 shown diagrammatically in FIG. 4. Thus a regulation of the suction according to the invention makes it possible to reduce the operating noise of said vacuum cleaner as well as reducing power consumption, unnecessary, during operations unsatisfactory for the user. otherwise the user obtains a sleep state from the vacuum cleaner if the the latter's nozzle is kept in the open air.

Another advantage of the vacuum cleaner according to the invention lies in the use of extremely simple means and inexpensive to perform regulation and / or control of said vacuum cleaner. Indeed part 10 is a part in molded plastic very cheap and easily mountable and removable in the vacuum cleaner. In addition the pressure switches U1, U2 or U3 whose ratings do not go below one worth around 8 millibars are very inexpensive. The circular shape, therefore symmetrical with respect to a axis located in the path of the air flow 20 and in a plane of extension perpendicular to said path of the air flow 20, of part 10 also reduces turbulence during of the passage of the air flow 20 through said part 10.

Another advantage of the vacuum cleaner according to the invention lies in the use of a room 10 in which is formed a calibrated opening 12 preferably circular. Such a calibration makes it possible to limit a flow or to adapt it depending on the use of pressure switches tared to specific values, or using a motor electric of determined power. Such a room 10 therefore adapts universally to any vacuum cleaner.

An additional advantage of the vacuum cleaner conforms to the invention lies in the operation of said vacuum cleaner with a dry air flow or a flow partially made up of liquid and air.

Claims (11)

1. A vacuum cleaner (1) including an electric motor (2a) driving a fan (2b) for creating internal suction and a sucked-up flow of air (20) so as to convey sucked-up dust to a dust collector (4), as well as control and/or regulation means for controlling and/or regulating the speed of the electric motor, which means are connected to an internal pressure measuring member (U3) for measuring an internal pressure, and at least one differential pressure measuring member (U2) for measuring a differential pressure of the flow of air, said control means being suitable for continuously controlling and/or regulating the speed of the electric motor to maintain the suction and the flow rate of the flow of air within limit values, as a function of the results of the suction measurements and of the differential pressure measurements, said vacuum cleaner being characterized in that the differential pressure measuring member (U2) comprises at least two measurement points (7a and 7b) mounted in the flow of air on either side of a part (10) provided with a calibrated aperture (12) for creating headloss.
2. A vacuum cleaner according to claim 1, characterized in that the part (10) is annular in shape so that it obstructs in part the flow of air.
3. A vacuum cleaner according to claim 1 or 2, characterized in that the part (10) is disposed in a measurement chamber (6) provided between the dust collector (4) and the fan (2b), the sucked-up flow of air flowing from the dust collector (4) to the fan (2b).
4. A vacuum cleaner according to any preceding claim, characterized in that the suction measuring member for measuring the suction produced by the fan is disposed in the dust collector (4) in the vicinity of an inlet orifice (5b) for the flow of air (20).
5. A vacuum cleaner according to any preceding claim, characterized in that the suction measuring member (U3) and the differential pressure measuring member (U2) are constituted by diaphragm pressure-sensitive switch assemblies.
6. A vacuum cleaner according to any preceding claim, characterized in that the control and/or regulation means comprise electrical contacts connected to an electrical or electronic circuit making it possible to vary the power supply voltage fed to the electric motor.
7. A vacuum cleaner according to claim 6, characterized in that the electrical contacts are actuated by the pressure-sensitive switch assemblies (U2 and U3), said contacts being connected in parallel in the electrical or electronic circuit for powering the electric motor.
8. A vacuum cleaner according to any one of claims 5 to 7, characterized in that the pressure-sensitive switch assemblies (U3 and U2) are rated at values lying respectively in the range 130 millibars to 150 millibars, and in the range 8 millibars to 15 millibars for a given calibration of the aperture in the annular part (10), said pressure-sensitive switch assemblies serving to interrupt or at least reduce the power supply to the electric motor whenever the suction or the differential pressure exceeds the corresponding rated value.
9. A vacuum cleaner according to claim 8, characterized in that the annular part (10) is provided with a calibrated aperture (12) that is circular, that is of diameter lying in the range 35 millimeters to 45 millimeters, and preferably in the range 39 millimeters to 41 millimeters.
10. A vacuum cleaner according to any one of claims 1 to 9, characterized in that, in association with the suction measuring member (U3) and the differential pressure measuring member (U2), it includes a second differential pressure measuring member (U1) for determining the filling level of the dust collector (4).
11. A vacuum cleaner according to claim 10, characterized in that the second differential pressure measuring member (U1) is constituted by a diaphragm pressure-sensitive switch assembly rated at a value lying in the range 50 millibars to 70 millibars, and connected via its inlets to measurement points (7 and 7a) situated in the dust collector (4).

Images