CA1120664A - Method for carpet cleaning - Google Patents

Abstract

"METHOD FOR CARPET CLEANING"

ABSTRACT
The invention relates to a carpet cleaning method wherein a fine spray of cleaning solution is uniformily applied to the carpet in an amount not more than necessary to dampen it. A preferred cleaning solution in the form of a non-ionic surfactant is disclosed. Once the cleaning solution is sprayed on the carpet, a cleaning pad, having a soft textile fiber pile, is then vigorously rubbed over the surface of the carpet to be cleaned, preferably in a rotary motion. This rotary motion can be accomplished through the attachment of the cleaning pad to a carpet cleaning machine as described. The cleaning pads may also be soaked in an aqueous solution of an electrolyte and wrung dry before use, and are replaced by clean pads when soiled.

Description

~Z6)664 SPECIFICATION

The present invention relates to a method for the cleaning of carpets.
Numerous methods and apparatus have been devised for cleaning carpets in residential and commercial installa-tions. The methods available for carpet cleaning generally fall into two classes: shampooing and steam cleaning. Each of these classes of carpet cleaning methods has its drawbacks, and there has been a considerable need for improved methods of cleaning installed carpeting.

Among the problems associated with shampooing methods are the inability of most known shampoos to remove certain types of soil and stains and, more importantly, the problem of residual soap left in the carpet by most shampoo-ing methods. The soap residue will, of course, add to the attraction of dirt by the carpet fibers and may cause a more rapid accumulation of soil in the carpet than might otherwise occur. Another problem associated with shampooing methods is that of not being able to use a room in which the carpet has been shampooed for considerable period of time because of the drying period typically required.
The steam cleaning of carpets does not present the residual soap problem presented by shampooing methods but may lead to serious shrinkage of the carpet. In addition, the drying period required after steam cleaning is extremely long and, in fact, may lead to the mildewing of the carpet in those areas which do not dry thoroughly.
The present method, using the machine disclosed herein, reduces the drying time to from one to three hours, dependent on the carpet material.

The presentinvention pxovides a carpet cleaning method comPrisinq aPPlyinq uniformly to a soiled carpet a fine spray of cleaning solution in an amount not more than that UZ0~64 required to dampen the carpet, said cleaning solution comprising a water-based solution of a non-ionic surfactant, applying on the carpet a cleaning pad having a soft textile fiber pile in contact with the carpet surface, with the free ends of the pad fibers direc-ted downward toward the carpet, vigorously rubbing the cleaning pad over an area of the surface to be cleaned until the pad has recei-ved substantially all the soil it can retain, periodically re-placing the cleaning pad with a fresh, clean pad when the pad becomes soiled and continuing the cleaning method until substan-tially all the soil on the carpet has been transferred to the cleaning pads.
It has been found that when a cleaning pad having a soft textile fiber pile is rubbed over a soiled carpet surface which is dampened with a non-ionic surfactant solution, dirt from the carpet migrates from the carpet into the pad. Without wishing to be bound by any theory, it is suggested that this migration is assisted by an electrostatic charge difference which arises between the material of the pad and the carpet, this charge being generated by the frictional rubbing of the pad material over the carpet.

A detailed example of the method of the invention is de-scribed hereinafter, using a form of apparatus as described and claimed in my Canadian patent no. 1,090,0~3 dated November 25, 1980, of which this application is a divisional.
It will be appreciated, however, that the present cleaning method is not limited to the use of any pa~ticular form of appara-tus, and that other forms of apparatus capable of rubbing the cleaning pad vigorously over the carpet surface may be employed.

Preferably, however, the rubbing is effected by rotating the pad in contact with the carpet surface.
The pad may be a nylon fiber pile pad, and, in the pre-ferred method, the cleaning pad is soaked in an aqueous solution of an electrolyte, and excess solution is squeezed out, before applying the cleaning pad on the carpet.

-, ~2~664 In the accompanying drawings:
Figure 1 is an elevational view of a carpet cleaning machine.
Figure 2 is a bottom plan view of the machine with the rotor removed.
Figure 3 is a circuit diagram a charge control means therefore.
Figure 4 is an exploded view of the components of the rotor assembly of the machine.
Figure 5 is a perspective view of the components of Figure 4 in assembly.
Figure 6 is a vertical section through the rotor assembly of Figure 5.
Figure 7 is an exploded view of the components of the rotor assembly of a second embodiment of the invention.
Figure 8 is a perspective view of the components of Figure 7 in assembly.
Figure 9 is a vertical section through the rotor assembly of Figure 8.
Referring first to Figures 1-3, the carpet cleaning machine comprises a carriage having wheels 12 by means of which the carriage may be moved. A handle 14 is pivotally connected to the carriage, and suitable latch means (not shown) are provided which permit the handle to be tilted to raise the carriage for transportation.
It will be understood that the machine includes a rotor assembly indicated in its entirety at 16 and here shown separated from the carriage. In use, this assembly rests upon a cleaning pad having a pile under-surface in contact with the carpet being cleaned, and the weight of the carriage and parts carried thereby is supported by the rotor and the cleaning pad engaging the carpet.
In the examples of cleaning machines described here-inafter in more detail, a specialized form of electrostatic charge-llZ0664 accumulating rotor 16 or 60 is employed which is provided with means for electrically grounding the upper side of the rotor.
It will be appreciated that the present method is not limited to the use of machines having an electrostatic charge-accumula-ting rotor and that the other forms of cleaning machine having a rotor for rotating the cleaning pad in contact with the carpet surface may be employed.
In the example shown in Figures 1 to 6, the rotor 16 includes a relatively large charge accumulator 18, and mounted within a insulation-lined hood 20 fixed to the carriage are a plurality of brush assemblies 22, each of which comprises an insulating support block 24, and a belt or brush element 26, preferably formed of conductive rubber. Connected to the brush is an insulated wire 28 leading through an adjustable spark gap 30 to a connection to the grounded third wire 31 of the motor 32, as best seen diagrammatically in Figure 3. The brush 26 remains in sliding, conducting contact with the flat upper surface of the static accumulator 18. Accordingly, when the static charge reaches the value at which a spark discharge occurs across the spark gap, the discharge provides an upper limit to the charge which may be maintained on the accumulator.
The adjustable spark gap 30 is mounted on insulating bracket 33 and includes a setting knob 34 by which the length of spark gap may be adjusted. In the use of the machlne shown in Figures 1 to 6, adjustment of the spark gap is desirable for different operating conditions, such as dictated by different characteristics of the particular carpet being cleaned.

Associated with the spark gap device 30 is a position-responsive switch 36 mounted on the carriage 10, the switch being in a bypass line 37 in parallel with spark gap 30. A con-ventional mercury switch is preferred and it is arranged so that when the carriage is tilted to a position in which the .

~2061~4 rotor might be exposed, switch 36 closes, connecting the accumulator 1~ to ground, thus discharging it. It will be appreciated that in the use of the machine as shown in the drawings, static charges of many thousands of volts are accumulated.
Referring now to Figures 4-6, there is illustrated one type of rotor that may be employed in this machine.

- 4a -llZ0664 The rotor, here designated in its entirety at 40, comprises an accumulator 42, formed of a plastic material capable of absorbing or accumulating a static charge. For this purpose, polyethylene plastic is entirely suitable, although other materials may be used. The accumulator 42 is provided with a recess 44 of circular cross-section and having a bottom wall 46, and a downward reduced, solid cylind-rical extension 48. As illustrated, the diameter of recess 44 and downward extension 48 are not materially different and are approximately one-half that of the outside diameter of the accumulator.
Secured to the underside of the accumulator 42 by fasteners 43 is a drive pad 50, preferably formed of low conductivity hard rubber having a central circular opening 52 dimensioned to receive the extension 48 of the accumulator.
The drive pad 50 has its undersurface provided with a multi-plicity of projections or nipples as indicated at 53 which engage with the upper, preferably waffled surfaces of dis-posable or replaceable cleaning pads, which are thus driven in rotation in frictional contact and under pressure conditions determined by the weight of the carriage with the upper sur-face of the carpet.
It will be observed that the vertical dimension of the extension 48 is the same as the thickness of drive pad 50, so that when drive pad 50 engages the upper surface of a cleaning pad, so also does the bottom surface of the extension 48.
Located within the cylindrical recess 44 is an annular core 54, secured in place by fasteners 55, which also secure the metal drive hub 56 in place. Core 54 is formed of insulating material, such as a phenolic resin.

llZU6~
The drive hub, as best seen in the exploded view of Figure 4, includes downwardly bent fingers 57 and key recesses 58, by means of which the entire rotor is connected in driven relation to the drive shaft (not shown) of the motor 32.
Referring now to Figures 7-9, there is illustrated a second type of rotor, here designated in its entirety as 60. Rotor 60 comprises an accumulator body 62 having a shallow annular recess 64 in its upper surface and a down-ward reduced, solid cylindrical extension 66 at its lowerend. Accumulator 62 is formed of a suitable plastic material capable of absorbing or accumulating a static charge, such as polyethylene, as previously described.
In this form of rotor, the use of a separate core such as shown at 54 in the rotor previously described is eliminated and a locking ring formed from three segments 68, as seen in Figure 7, is seated in shallow recess 64 and retained in place by fasteners 69. Segments 68, shaped as shown, may be spot-welded into a continuous ring having upstanding, interlocking tabs for engagement with suitably shaped drive and support elements (not shown) on the motor drive shaft.
With this arrangement, use of the static build-up assembly comprising brushes 26 and related structure is eliminated. The accumulator 62 is at all times connected to the grounded third wire of the circuit energizing motor 32, and build-up of high voltage charge on the accumulator is avoided. Instead, while static charges are created by the sliding a~tion of the cleaning pad over the carpet, there is a continuous flow-through action from the cleaning pad to the grounded hub of motor 32, thus constituting a bleed-off through the machine to ground. Locking ring 66 thus liZC)664 constitutes a ground connection whenever accumulator drive block 62 is locked in place on the motor drive shaft.
An annular drive pad 72, preferably formed of slightly conductive hard rubber, is provided with enlarged central aperture, and is secured to accumulator 62 by fasteners 76.
In operation, drive pad 72 causes the cleaning pad to slide over the upper surface of the carpet, thus creating a static charge.
In carrying out the present cleaning method, the carpet to be cleaned has a fine spray of cleaning solution applied uni-formly thereto. The amount of cleaning solution is typically about one gallon per two thousand s~uare feet, which amount may be varied in accordance with the nature of condition of the carpet. This amount is sufficient merely to slightly dampen the carpet. Circular cleaning pads are provided, preferably having a soft textile fibre pile lower surface, of which nylon or wool pile e.g. as in carpeting material, has proved particu-larly effective. The cleaning pads preferably have an upper surface which is waffled or otherwise shaped to cooperate with the undersurface of the drive pads. These pads are replaceable, when they have received a full load of dirt particles and the like. Before use, they are preferably saturated with an electro-lyte solution which may be an aqueous solution of potassium chloride, or acetic acid as present in ordinary vinegar. Excel-lent results have been obtained when four ounces of a molar solution of KCl is dissolved in one gallon of water. After excess solution has been squeezed out of the cleaning pad, the apparatus is placed into operation with the drive pads trans-ferring the weight of the frame, motor, etc., directly to the cleaning pads. The motor 32 is energized and drives the rotor assembly and cleaning pads at moderate speed ~lZ~)664 for example, about 1700 to 1800 r.p.m. The carriage is moved over the carpet manually until clean.
Dirt particles in the carpet are loosened by the pile surface of the cleaning pads and migrate into the cleaning pads. Periodically, when a cleaning pad has received sub-stantially all the soil it can retain, it is replaced by a fresh, clean pad. The cleaning solution, described in more detail below, has a detergent action and assists in loosening dirt, dissolving grease, etc. In the preferred form, the cleaning solution also acts on electrolyte due to the presence of salts dissolved therein.
When a machine having an electrostatic charge accumulating rotor is used, as in the example of the carpet cleaning machine shown in Figures 1-6, rotation of the rotor against brushes 26 and/or rotation of the cleaning pads against the carpet establish a high static charge on accumu-lator 42, which is limited by spark-gap device 30.
With this machine, excessively high voltage charge is prevented by the spark discharge device, and the charge is automatically dissipated when the cleaner carriage is tilted.
The operation of the machine including the rotor of Figures 7-9 is essentially the same, except that the necessity for the static build-up assembly comprising brushes 26, the spark-gap device 30, and the switch 36, is avoided.
Here, rotation of the accumulator, drive pad 72, and the replaceable cleaning pad, creates a static charge as a result of friction resulting from rotation of the cleaning pad against the carpet. This static charge does not create the high voltage resulting from use of the rotor and mechanism shown in Figures 1-6. Instead, the static electricity is continuously bled away, resulting in what may aptly be described as a flow-through action. However, in the operation ~ZC;~66~

of this machine a static charge is maintained on the accumulator while the rotor is driven at a value sufficient to cause migration of dirt particles ancl other contaminants to the cleaning pad from the carpet.
When using the machine as illustrated in the drawings, by employing a controlled static charge, established by friction between the rotating cleaning pad, or by friction between the accumulator and the static build-up assembly, or both, and the use of a cleaning solution using the sodium sulphate and so~ium tripolyphosphate as detergent agents, soiling materials may be dissolved and mechanically loosened from the carpet material and pulled by the static charge into the electrostatically charged pad.
In use, a cleaning solution is sprayed onto the carpet. The cleaning pad is soaked in electrolyte solution and wrung dry. The pad is then placed in contact with the sprayed carpet. The machine having a rotably driven accumu-lator, engineered to serve as a part of a variable static charge accumulator, is positioned with its lower surface in contact with the pad and is rotated, thus rotating the pad under the weight of the machine and creating static forces which attract all foreign matter in the carpet. In one embodi-ment, the machine has been modified to generate additional static attraction and to store and regulate the intensity of static charge and the static attraction to foreign matter, along with safety controls as follows:
The capacitor has been engineered and construc-ted out of a static absorbing plastic product, preferably poly-ethylene plastic, acting as a static charge accumulator for the accumulation, storage and power source of the static electrical charge generated by this system.

In one example of the machine shown in Figures 4-6, the accumulator is isolated from the buffer driving hub by means of a machined phenolic socket inserted and secured 'A~ _ g ....

, 112~66~
into the plastic capacitor. In this construction, the drive hub locking device used to secure the rotor to the buffer drive hub is mounted in the machined phenolic socket, thus isolating it from the plastic condenser.
In this arrangement, the electrical static build-up assemblies consists of four non-conductive isolating pads, four phenolic brush mounting blocks, and four conductive rubber belts. These static build-up assemblies are mounted in the upper section of the buffer shroud or hood. With these four assemblies secured in place, the four belts or brushes will touch and drag the top of the plastic condenser or accumulator when it is secured to the drive hub of the machine. As the rotor spins with the belts brushing the surface thereof, a static electrical charge is built up on the accumulator.
The rotatably driven accumulator is constructed to cause the lower center section to extend through the center opening in the driving pad or ring, contacting the back of the cleaning pad and thus allowing the static electricity created by the friction of the pads' circular motion on the carpet, combined with the chemicals, to flow through the pad into the capacitor, thus creating the static charge which results in the draw or pick-up of all foreign matter in the carpet.
The fasteners, which are preferably stainless steel screws, securing the driving pad to the accumulator, also act as contact points to the back of the cleaning pad. These contact points assist in the static electrical transfer of positive to negative charges. The negative charge applied to the cleaning pad, collects and holds all the foreign matter from the carpet being cleaned.
To obtain a high static voltage build-up in the plastic accumulator, the following steps have been taken:

1. Complete isolation of the static charge accumu-llZ6)6~4 lator from the machine drive hub by means of the phenolicinsulating soeket.

2. Heavily insulated high voltage discharge wire used through the static system.

3. The buffer hood or shroud covering the rotor is rubber coated on the inside to prevent static leakage.

4. Brushes running in contact with the top side of the accumulator are installed as a completely insulated assembly.

5. Gap control of the spark gap and the mercury safety switch are made of insulating plastic and mounted on an installation pad of insulating material.

6. All electrical connections are shielded against leakage.
The value of static high voltage build-up in the accumulator is controllable through the adjustable spark gap or bleed-off system. This adjustable spark gap has been wired into the system using the third wire ground circuit of the buffing machine as for bleed-off of excess high voltage above the spark gap setting.
When using the machine illustrated in Figures 1 to 6, each cleaning application may require a change in the gap setting.
The type of earpet, material and above all the condition of the carpet, all contribute to the amount of static draw or pick-up required. Carpets that have been treated with foam or other types of soaps may have to be cleaned two or three times with the present method before all of this residue is removed.
It has been found that there is no perceptible resi-due left in the carpet by practice of the present invention.
In the carpet cleaning machine using the rotor of Figures 7-9, the accurnulators are made of static absorbing plastic material such as polyethylene, and are so engineered and constructed as to prevent the build-up of electrical 6~
static high voltage. Instead, they permit a continuous flow through action from the cleaning pacl to the dxive hub of the machine, thus setting up a bleed-off through the machine to the third wire ground circuit of the unit.
To accomplish this flow-through action, the phenolic insulating socket and the static build-up assemblies of Figures 1-6 are eliminated. This allows securing the locking device directly to the plastic condenser, thus making the locking device a ground connection to the third wire ground circuit of the buffing machine whenever the rotor is locked in place on the drive hub.
Cleaning Solution A preferred cleaning solution which has been found entirely satisfactory, both from the standpoint of efficiency in cleaning as well as the condition in which it leaves the cleaned carpeting, will be described. It will be understood, however, that other cleaning solution may be employed.
Essentially, the cleaning solution is a water based solution of non-ionic surfactant e.g. an Alfonic (trade mark), an organic solvent for hydrocarbon contaminants such as grease or oil, e.g. petroleum naptha and lower alcohols, and selected inorganic detergent or detergency-building salts e.g. sodium tripolyphosphate and sodium sulphate.
A specific cleaning solution has been used very successfully and has the following formulation, with percentages by weight:

Surfactant* 0.5 - 2.0%
Petroleum Naphtha 0.5 - 2.0%
Butyl Alcohol 1.0 - 5.0%
Sodium Sulphate 1.0 - 5.0%
Sodium Tripolyphosphate 3.0 - 8.0 with the balance water *A surfactant sold by the Continental Oil Company under the trade name "Alfonic"
is preferred.

It is important that this cleaning fluid be thoroughly 1~20~;64 intermixed and dissolved to prevent subsequent partial separation. This is a two-stage procedure in which certain groups of chemicals are mixed in a fairly small tank and then transferred to a large tank for the final mixing and suspension.
A circulating pump with a capacity of approximately 8000 gallons per hour and having an intake and an exhaust port of two-inch diameter is used throughout this procedure.
The mixing is done in four distinct steps and should be followed closely to acquire the correct suspension of this formula.
Step 1 One and one-half gallons of Alfonic (surfactant), seven gallons of mineral spirits, 3 gallons of butyl alcohol and approximately ten gallons of water are first mixed in the small tank. This mixture is then circulated through the pump and back into the small tank for forty-five minutes.
This solution is then transferred to the large holding tank.
Step 2 Four gallons of sodium tripolyphosphate and ten gallons of water are put into the small tank and this solution is circulated for forty-five minutes until thoroughly dis-solved through the pump and back into the small tank. It is then transferred to the large holding tank.
Step 3 One-half gallon of sodium sulphate and ten gallons of water are put into the small tank. This solution is circulated for ten minutes through the pump and back into the small tank. This solution is then transferred to the large holding tank.
Step 4 With these three mixtures combined in the large tank, one hundred and ten (110) gallons of water is then added as it is being circulated through the pump and back llZ0664 into the large holding tank. This mixing and circulating pro-cedure is continued for at least one hour to properly dissolve and suspend the chemicals in this formula. While this solution is being thoroughly mixed and suspended, a perfume of choice may be added if desired.
Packaging may be done any time after this mixing pro-cedure has been completed. The cleaning fluid, thus prepared, remains in suspension indefinitely and has unlimited shelf life. It is completely non-flammable, and of course has no flash point, an important consideration in view of the presence of static electrical charges resulting from the method disclosed herein.
The dimensions of the accumulator used in the machines shown in the drawings are such as to permit it to carry a static charge effective to produce migration of dirt and con-taminants from the carpet, and also to cover a reasonable width of carpet when moved thereover. The vertical dimension of the accumulator when used, should be at least three inches, its diameter twelve inches, the pad driver a thickness of about one inch and a diameter of at least twelve inches and preferably fourteen inches, and the diameter of the opening in the pad driver and of the downward extension of the accumulator a dia-meter of at least four inches and preferably more than five inches.
As discussed above, although applicant does not wish to be bound by any theory, it is suggested that the migration of dirt particules from the carpet to the cleaning pad is assisted by an electrostatic charge difference which is generated between the cleaning pad and the carpet. This generation of static electricity may result from friction between different materials having different static charge potentials, e.g.

between the preferably nylon pile of the cleaning pad and the carpet. Further, an electrostatic charge difference may be generated between the plastic accumulator and the hard , ~12~)66~

rubber brushes, when used.
It is suggested that the ac~ual static electricalvoltage is not highly critical, as the cleaning action starts as soon as the cleaning pad is rubbed on the carpet. However, when the machines as illustrated in the drawings are employed, it appears that the cleaning action improves as the voltage increases, up to the point where attraction between the pad and carpet overloads the motor of the machine, in some cases actually stalling it.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A carpet cleaning method comprising applying uniformly to a soiled carpet a fine spray of a cleaning solution in an amount not more than that required to dampen the carpet, said cleaning solution comprising a water-based solution of a non-ionic surfactant, applying on the carpet a cleaning pad having a soft textile fiber pile in contact with the carpet surface, with the free ends of the pad fibers directed downward toward the carpet, vigorously rubbing the cleaning pad over an area of the surface to be cleaned until the pad has received substantially all the soil it can retain, periodically replacing the cleaning pad with a fresh, clean pad when the pad becomes soiled, and continuing the cleaning method until substantially all the soil on the carpet has been transferred to the cleaning pads.

2. A method according to claim 1, in which the cleaning pad is a pad of carpeting material.

3. A method according to claim 1, in which the cleaning solution is a water-based solution containing a non-ionic surfactant, an organic solvent, and an inorganic detergency-building salt.

4. The method as defined in claim 1, in which the cleaning solution is a water-based solution containing, by percentage weight of the solution:

Surfactant 0.5 - 2.0%
Petroleum Naptha 4.0 - 7.0%
Butyl Alcohol 0.5 - 3.0%
Sodium Sulphate 1.0 - 5.0%
Sodium Tripolyphosphate 3.0 - 8.0%

5. A method according to claim 1, 2, or 3, wherein each cleaning pad is soaked in an aqueous solution of an electrolyte, and excess solution is squeezed out, before applying the cleaning pad on the carpet.

6. A method according to claim 4, wherein each cleaning pad is soaked in an aqueous solution of an electrolyte, and excess solution is squeezed out, before applying the cleaning pad on the carpet.

7. A method according to claim 1, 2, or 3, in which the rubbing action is effected by rotating the cleaning pad in contact with the carpet surface.

8. A method according to claim 4, in which the rubbing action is effected by rotating the cleaning pad in contact with the carpet surface.

9. A method as claimed in claim 1, 2, or 3, in which the cleaning pad has a nylon fiber pile.

10. A method as claimed in claim 4 in which the cleaning pad has a nylon fiber pile.