EP0563788B1 - Working process for a wet-dry cleaner having an automatic cut-out system and wet-dry cleaner operating accordingly - Google Patents

Abstract

A process for operating a wet-dry cleaner (1) having an automatic cut-out of the turbine (28) and an electric tool (18), which may be connected thereto, provides for an impermissibly high loading of dirt to be detected in the case of the loading of dirt of the filter (15) and/or of the dust bag (14) being exceeded or in the case of any other disturbance in the suction region, due to the fact that either the absolute pressure is recorded on the intake side of the fan wheel (16) of the turbine or a differential pressure is recorded in the region of a Venturi plate (21) on the entry side of the fan wheel. <IMAGE>

Description

The invention relates to a method for operating a vacuum cleaner with automatic shutdown and a vacuum cleaner for performing this method according to the preamble of claim 1.

Such vacuum cleaners are generally used in conjunction with a power tool or the like, the power tool having suction slots in order to be able to vacuum off contaminants generated by the power tool and be supplied to the vacuum cleaner. The problem with vacuum cleaners in connection with a power tool is that different, dust-generating power tools with different cross-sectional areas and with different suction hoses are connected from the power tool to the vacuum cleaner to a single vacuum cleaner.

Depending on the flow resistance in the tool with the suction slots, in the suction hose and in the wider area of the suction section, there is a higher or lower suction resistance. A certain automatic switch-off is now arranged within the vacuum cleaner in order to be able to switch off the vacuum cleaner and / or the tool in the case of a certain impermissibly high suction resistance in connection with the connected tool, or in the event of filter contamination of the vacuum cleaner.

So far, it has happened according to the prior art that different suction tools were connected to a vacuum cleaner with a certain automatic switch-off, different suction hoses being used depending on the system. The problem that arises here is that a certain suction tool has a certain system-related suction hose is assigned, which has a small diameter, for example, which, without contamination being present, created a high suction resistance and thereby switched off the automatic switch-off of the vacuum cleaner.

For example, DE-U-8 704 714 shows a vacuum cleaner with air volume control, in which the air volume conveyed or its intake speed is recorded and is kept essentially constant by means of a control system. This regulation only works depending on the fill level of the filter; an adaptation to device-related changes in the suction resistance is not provided.

The invention is therefore based on the object of developing a method for operating a vacuum cleaner in such a way that, regardless of the suction hose diameter used and other circumstances influencing the efficiency of the suction on the power tool, care is always taken to ensure that the power tool is not sucked off with a too low volume flow .

The technical teaching of claim 1 serves to solve the problem.

Circumstances that could lead to an unacceptable drop in the minimum volume flow on the power tool are e.g. a decrease in the operating voltage of the vacuum cleaner, the speed of the turbine decreasing and thereby a lower volume flow being sucked off. Other circumstances include the use of different suction hoses with different diameters, which also influences the volume flow on the power tool.

According to the invention, the volume flow prevailing in the vacuum cleaner is measured and included in a calculation formula, on the basis of which a minimum volume flow not to be undercut is calculated, when it is reached the power tool and / or (possibly with a time delay) the vacuum cleaner are switched off.

It is provided that the volume flow per unit of time is recorded on the intake side of the turbine fan wheel.

For this purpose, it is provided that the differential pressure is measured in the area of a Venturi orifice, which is arranged in front of the suction side of the fan wheel of the turbine.

• a) beim Betrieb des Staubsaugers zum Aufsaugen von abgelagerten Stäuben die Mindest-Luftgeschwindigkeit im dabei verwendeten Saugschlauch den Wert von 20 m/s nicht unterschreitet,
• b) beim Betrieb des Staubsaugers als Entstaubers zur Absaugung von Stäuben, erzeugt durch stauberzeugende, handgeführte Maschinen, z.B. Elektrowerkzeuge, wie Rutscher, Winkelschleifer usw., die Mindest-Luftgeschwindigkeit von 20 m/s im Absaugstutzen des dabei verwendeten stauberzeugenden Werkzeuges nicht unterschritten wird.

In the described method it is important that a minimum volume flow is not undercut, which corresponds to a minimum air speed of 20 m / s required. In this way, the requirements of the professional association, which stipulate that

• a) when operating the vacuum cleaner to vacuum deposited dust, the minimum air speed in the suction hose used does not fall below 20 m / s,
• b) when operating the vacuum cleaner as a dust extractor for the extraction of dust, generated by dust-generating, hand-held machines, e.g. power tools, such as slides, angle grinders, etc., the minimum air speed of 20 m / s in the extraction nozzle of the dust-generating tool used is not undercut.

As already stated at the beginning, this minimum volume flow depends on a number of factors, namely, for example, the degree of soiling of the power tool, the degree of soiling of the suction hose, the degree of soiling of the filter bag and the filter, the speed of the turbine (and thus also fluctuations in the network) and from other circumstances more.

It is important that a switch with several switch positions is arranged on the control panel of the vacuum cleaner, with which different minimum volume flows can be specified on a scale arranged around the switch, at which the vacuum cleaner and / or the power tool are switched off (if one Power tool is switched on).

This makes it possible to connect different types of power tools with different intake manifold diameters to a vacuum cleaner and still ensure that the minimum volume flow assigned to the power tool is not undercut.

The minimum volume flow assigned to the respective power tool is e.g. determined by the trade association, determined and in future documented on the nameplate and the operating instructions for the power tool.

The fact that the minimum volume flow is not undershot is achieved by turning the switch mentioned in such a switch position that indicates the minimum volume flow on the fixed scale. The drop in the minimum volume flow is then monitored in the control of the vacuum cleaner.

In a further development it is provided that during operation of the vacuum cleaner for vacuuming deposited dust, the suction hose diameter is available as a coded number through correspondingly arranged contacts in the connecting sleeve of the suction hose, and that this coding is tapped via a corresponding contact arrangement in the inlet opening of the vacuum cleaner. to tell the control unit of the vacuum cleaner which type of suction hose is connected. The previously mentioned switch is then no longer necessary, with which the control of the vacuum cleaner is informed which type of suction hose is connected.

In another embodiment it is provided that the previously mentioned volume flow measurements directly in the inlet area of the vacuum cleaner, i.e. For example, in the area of the inlet opening, so as not to fall below a minimum volume flow.

The invention is explained in more detail below with the aid of drawings illustrating an embodiment.

Figur 1:

schematisiert einen Schmutzsauger mit angeschlossenen Werkzeug,

Figur 2:

einen Schnitt durch einen Schmutzsauger mit Darstellung des Meßortes für eine Differenzdruckmessung;

Figur 3:

ein Volumenstromdiagramm unter Verwendung der Differenzdruckmessung.

Show it:

Figure 1:

schematically shows a vacuum cleaner with attached tool,

Figure 2:

a section through a vacuum cleaner showing the measuring location for a differential pressure measurement;

Figure 3:

a volume flow diagram using the differential pressure measurement.

In Figure 1, a vacuum cleaner 1 is shown schematically, which has in its cover 2 a fan wheel 16 which is part of a turbine 28 (see Figure 2) and which is driven by an electric motor, not shown.

The vacuum cleaner 1 also has a dirt container 13 in which a filter bag 14 is arranged in a manner known per se.

The filter bag 14 is connected in an airtight manner to an inlet opening 33, to which a suction hose 17 attaches, which is connected to an electric tool 18.

In the interior of the dirt container 13 there is also a filter 15 which is designed, for example, as a pleated filter.

The filter 15 covers a ventilation grille 22 on the clean air side, through which the air sucked in through the filter bag 14 and through the filter 15 is sucked in by the turbine and flows out into the cover 2 in the direction of the arrows shown.

According to FIG. 2, the turbine 28 has outlet openings 39, the turbine being held in upper and lower seals 30. The lower seal 30 is arranged in the area of a receiving plate 29, while the upper seal 30 is arranged in the area of a clamping plate 31.

A wire mesh 38 is arranged on the underside of the turbine in the area of the receiving plate 29, in the area of which a venturi screen 21 is arranged. The venturi cover 21 consists of two tube pieces 41, 42 arranged coaxially to one another, which form two annular chambers 40, 44 between them, the lower annular chamber 40 being separated from the upper annular chamber 44 by a horizontal transverse partition 43. One port 45 for the decrease in pressure P4, for the one vacuum line, is now in the area of the lower annular chamber 40, while the other port 46 for the decrease in pressure P3 is in the area of the upper annular chamber 44.

By attaching the two pipe sections 41, 42 and the formation of the two horizontally superimposed annular chambers 40, 44, a higher inlet pressure P4 is achieved by the formation of the lower annular chamber 40, and, moreover, undesirable air noises that can arise due to the high volume flow are avoided .

This results overall in a higher delta p, which is calculated as the difference between the pressure P4 and the pressure P3.

The differential pressure cell 20 is therefore connected to the connections 45, 46.

This measurement method results in a volume flow diagram, which is shown in more detail in FIG. 3.

In the following, a volume flow diagram is drawn in FIG. 3, which works with the differential pressure method as it is constructed in FIG. 2.

P3 =

ist der Druck stromabwärts der Venturiblende 21 und der Druck

P4 =

ist der Druck im Innenraum des Filters 15.

The following are defined as pressure values:

P3 =

is the pressure downstream of the venturi orifice 21 and the pressure

P4 =

is the pressure inside the filter 15.

It is important that the differential pressure delta p is removed shortly before and after the venturi orifice 21 in order to obtain exact values.

ergibt.The volume flow V is plotted on the abscissa, while a differential pressure delta p, which results from the differential pressure, is plotted on the ordinate $\text{Delta p = p4-p3}$

results.

It now emerges that only a single straight line 47 is generated for a specific turbine type and is independent of the position of the supply voltage for the drive motor of the turbine.

Depending on the voltage, only the maximum value for the volume flow changes, as entered in points 48 to 50.

The corresponding absolute pressures per operating point 48,49,50 change accordingly.

It is now important that the switch-off point 51 is always on this straight line 47 regardless of the voltage, and this switch-off point corresponds, for example, to a differential pressure of 250 Pa at a volume flow of 26 cbm / h.

At a nominal voltage of 230 V, the working range is in the direction of arrow 52, starting from point 49, down until the lower switch-off point 51 is reached.

Due to test regulations, e.g. of the BIA (Berufsgenossenschaftliches Institut für Arbeits Sicherheit) must comply with minimum volume flow values, which must not be undercut, so that an optimal extraction on the tool is ensured and thus a hazard to the operator can be excluded.

With increasing pollution of the power tool or the vacuum cleaner (filter and filter bag), one moves down the straight line 47 in the direction of the arrow 52 until a maximum switch-off point 51 is reached, which a volume flow of e.g. Corresponds to 26 cmb / h, to which an absolute pressure of 20,500 Pa is assigned.

At this point, a signal must first be generated, which can be given optically or acoustically. After generating this signal, the power tool can optionally be switched off.

If no power tool is used, but the vacuum cleaner, is only used for vacuuming up possibly dangerous dusts, an optical or acoustic signal lights up in point 51 and the vacuum turbine may be switched off after a certain delay.

It is now provided that a volume flow switch is arranged on the front of the device, e.g. selectable volume flows from 25 cbm / h to 100 cbm / h in several stages and can be selected.

Indirectly, each volume flow value is assigned a pressure switch with a fixed switch-off value that can be selected from the switch.

This means that with the presetting of the volume flow, the switch-off time, i.e. change the switch-off point 51.

The selection of the volume flow is based either on the diameter of the suction hose used or on the connecting piece diameter of the power tool used.

This has the advantage that this suction device according to the invention can be adapted to all power tools on the market and their suction nozzle.

In the drawing Figure 3 it is plotted that there are no coulters for certain suction hose diameters, but only fixed points. For a suction hose of e.g. 36 mm diameter with a nominal voltage of 230 V, the value is 100 m3 / h (9), meanwhile, if the same suction hose when a nominal voltage drops to e.g. 200 V is used, the value is 80 m3 / h (9 ').

If a 27 mm diameter hose is used as an alternative, a higher value (11) will be generated, which will drop from 230 V to 200 V to the value (11 ') when the nominal voltage drops.

So you are always with your working points on line 47.

The advantage of the differential pressure decrease is that you are independent of the nominal voltage of the turbine and independent of the atmospheric pressure, i.e. it does not matter whether you have the turbine at sea level or on a mountain peak of 2000 m.

Claims (5)

1. A method for operating a dirt suction apparatus with automatic cut-off of the turbine and if necessary of an electric tool connected thereto on exceeding the loading of the filter and/or of the filter bag with dirt, in which the filter bag is arranged in the dirt container and the connecting socket (3) of a suction tube (17) opens into the dirt container, which suction tube is connected if necessary with an electrical tool, the current connection of which is connected to a power supply socket arranged on the dirt suction apparatus, in which to detect an unduly high loading of the filter (15) and/or of the filter bag (14) with dirt, the volume flow per unit of time is detected on the intake side of the fan wheel (16) of the turbine (28), characterised in that the determining of the volume flow per unit of time takes place by detecting the differential pressure ( $\text{Delta p=p3-p4}$

   

   ) in the region of a Venturi shutter (21) which is arranged in front of the intake side of the fan wheel (16) of the turbine (28).
2. A method according to Claim 1, characterised in that a minimum volume flow is associated with the cut-off point for the dirt suction apparatus and/or the connected electrical tool (18), to which a minimum velocity of flow (v) of 20 m/s corresponds, measured in the suction connecting piece (4) of the connected electrical tool or in the connected suction tube.
3. A device for carrying out the method according to one of Claims 1 - 2, characterised in that a switch is arranged on the front side of the dirt suction apparatus, by which different minimum volume flows can be preset, at which the dirt suction apparatus and/or the electrical tool are switched off, and in that different cross-sections of the suction connecting piece and minimum volume flows resulting therefrom are associated with the switching positions of the switch.
4. A device according to Claim 3, characterised in that the diameter of the suction tube is arranged as electrical coding in the connecting socket (3) of the suction tube, and in that this electrical coding is detected by the dirt suction apparatus in the region of the inlet opening (32) at the connection of the suction tube and can be preset with the electrical coding of the minimum volume flow which is not to be fallen below.
5. A device according to one of Claims 3 or 4, characterised in that the minimum volume flow associated with the electric tool is associated as electrical coding in a multipolar power supply plug of the electrical tool, by contact pins being connected in a particular manner internally by bridges in a multipolar power supply plug so that the cut-off points associated with the respective electrical tool are detected automatically on the evaluation electronics. The multipolar power supply plug additionally serves to transfer the power supply voltage to the electrical tool.

Images