FIELD OF INVENTION The present invention relates to brush. More particularly, the invention relates to brushes with overmoulded brush strips and a method of manufacturing the same.

BACKGROUND OF THE INVENTION

Vacuum cleaners are developed for specific markets based on criteria such as type of residence, cleaning frequency and floor material. The construction of brush associated with such cleaning devices needs to address the cleaning difficulties that the vacuum cleaner is aiming to resolve. The key metric of vacuum cleaner performance is the pickup and the cleaner head is critical for this operation.

Also, a variety of brush types are required to maximize the cleaning effectiveness of a vacuum cleaner. Long, stiff bristles are preferable for plush carpet cleaning. On hard floors, long, soft bristles are used to avoid scratching or marking the floor. Soft, short bristles reduce the risk of the brush bar stalling on rugs.

There are prior arts such as US 4307479, GB 1457074 and JP 5492971 that describe the design, manufacturing and assembly of brush strips for vacuum cleaners. However, there is a continuing need for improved brushes.

SUMMARY OF THE INVENTION

The present invention relates to the brush with overmoulded brush strips and a method of manufacturing the same for vacuum cleaners.

It is an object of the present invention to provide a brush with overmoulded brush strips for contemporary vacuum cleaners with maximum cleaning effectiveness.

it is another object of the present invention is to provide brush strips which are durable.

It is yet another object of the present invention to provide brush strips that are economically viable to manufacture in terms of cost and time. in an embodiment, the brush with overmoulded brush bar strips is manufactured by knitting yarns of carbon fiber or nylon into spools. Then an adhesive is applied at specific areas using an automated gluing machine and cured for 24 hours. 'Hie knitted yarns are cut into the desired brush strip length after which the strips were overmoulded to form a brush strip. The overmoulded brush strips are shearcd-slitted into two halves to produce two brush strips. The bristles are then trimmed and fine trimmed to the desired dimensions. The finished brush strips are then assembled into the brush bar.

In an advantageous aspect, the brushing solution is both technically sound and economically viable. in an emrxxliment, the present invention provides a brush strip protruding radially from the brush bar at 90° with both the stitching yarns embedded in the carrier. This design is for a soft roller brush bar where the brush bar core is covered with relt and used for hard floor cleaning. The brush strips sweep large debris into the suction section.

In an embodiment, the present invention provides a brush strip protruding radially from the brush bar at 90* with a blend feature. This design is an extension of the soft roller brush bar. The blend feature is introduced to reduce the total strain on the brush and improve the bend recovery. in an embodiment, the present invention provides a brush strip protruding radially outwards from the brush bar at approximately 65° with the top most yarn partially embedded in the carrier, litis design is to improve the bristle stiffness and to improve the sweeping angle.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, wherein like reference numerals denote corresponding pans throughout the several views:

Fig. l a & lb shows cleaner head components of a brush in accordance with an embodiment of the present invention.

Fig. 2a Si. 2b shows Brush Strip and Brush bar in accordance with an embodiment of the present invention. Fig. 2c shows brush strip in accordance with an embodiment of the present invention.

Fig. 3 shows a block diagram depicting the flow of manufacturing of brush in accordance with an embodiment of the present invention.

Fig. 4 shows Knitted strips in accordance with an embodiment of the present invention. Fig. 5 shows Gluing Process for manufacturing of brush in accordance with an embodiment of the present invention.

Rg. 6a & 6b shows a Knitted Strips Before Overmouiding in accordance with an embodiment of the present invention.

Fig. 7a, 7b & 7c shows Overmouiding Process in accordance with an embodiment of the present invention.

Fig. 8 shows Knitted Strips after slitting in accordance with an embodiment of the present invention.

Fig. 9a shows brush Strip with 90"' radial angle in accordance with an embodiment of the present invention. Fig. 9b shows Brush Strip with 90° radial angle and blend in accordance with an embodiment of the present invention.

Fig. 9c shows Brush Strip with 65° radial angle in accordance with an embodiment of the present invention.

Fig. I0a shows brush with 90° radial angle brush strip in accordance with an embodiment of the present invention.

Fig. 10b shows brush with 65 ^¾ radial angle brush strip in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to customized brush strips assembled into motor-driven brush bars of vacuum cleaners. In an embodiment, the present invention provides a brush cleaner head (100a, 100b) having a housing ( ^{ 10a, 1 10b), solepiate (120a, 120b), motor (130). brush bar (140), brush strip (150), driven pulley (160), driving pulley (170) and belt (180) (Fig la & lb), ^'{" he brush has to be optimized in parallel with the latest features of the brush bar, solepiate and other elements to maximize the vacuum cleaner capability (Fig 1 a & 1 b).

In an embodiment, vacuum cleaner brushes (200a, 200b) are either inserted directly into the brush bar through bristling, or manufactured as brush strips (Fig 2a) and assembled into the brush bar (Fig 2b).

There are two parts that form the brush strip: a carrier made from overmoulded thermoplastic and a filament body (Fig 2a).

Referring to Fig 2a, 2b & 2c, a brush strip (200a), brush bar (200b) and brush bar assembly (200c) Is shown that includes filament body (201a) and carrier (202a). According to an embodiment of the present invention consists of the channel (210a), lip (220a), body (230a), base (240a), bristle tufts (250a) and bristle tip (260a). The channel (2i0a) is the slot that holds the bristles within the strip. The Up (220a) is the upper part of the carrier that extends beyond a brush bar groove (270) and prevents the brush strip (295) from slipping out of the groove (270). The body (230a) is the carrier part (202a) connecting the lip (220a) and the base (240a). The base (240a) slides into the brush bar groove (270) and supports the brush strip/tufts (250a). The brush bar includes a core (280) with ingress end (290) and drive end (292). In an embodiment the present invention provides manufacturing flow 300 for brush bar assembly as shown in Fig 3.

Referring to Fig 4, a knitted filament body (400) consists of the warp (410), weft (420) and selvedge/selvage (430). The weft (420) consists of long strands of yarn that run lengthwise on the loom. The warp (410) is the yarn that is perpendicular to the lengthwise yam. It goes over and below the weft. The warp 410 (410a, 410b) is also known as the stitching yam or the knitting yarn. In one embodiment of the present invention, there are two warps, identified as the top warp (410b) and the bottom warp (410a). The selvedge (430) is the edge of the yam that is folded and prevents the edges from fraying. In an embodiment, the brush strip manufacturing starts when the monofilament fibers are knitted to form a body and two folded ends. The body portion comprises fibers arranged in parallel. The end loops/selvedge (430) is formed when the weft (420) fibers are folded. The warp (4 i 0) stitching across the body portion interlinks the individual bundles. In the present invention, two rows of stitching are applied at both ends. in an embodiment, as shown in Fig. 5. the knitted spools are handed to the gluing station (600). An adhesive agent is applied over the stitching yam. Tha adhesive binds the warp to the weft. This process secures the two yarn bundles that are perpendicular to each other. The gluing process is an important additional process because it provides additional strength to the weft and warp binding. It prevents loose filaments and increases the bristle retention strength. Additionally, the adhesive line parallel to the warp, forms a barrier preventing flashes leaking into the bristle tufts during overmoulding.

Without the adhesive barrier, the molten plastic will seep through from the overmoulded region into the bristle tufts to form flashes. Flashes are a potential reliability problem. The bristle tufts would be hardened by the plastic compound, reducing the brush strip deflection capability, causing bristle drop-ofJf after usage.

The gluing process requires high accuracy for controlling the volume of the adhesive constituents, in dispensing the required volume and at the correct location. The adhesive is dispensed approximately 2mm from the selvedge. There are different dispensing volume requirements for carbon fiber and nylon because of the adhesive properties. The carbon fiber strip requires 0.025 to 0.028 g/em. The nylon strip requires 0.016 to 0.020 g/cm.

Due to the stringent requirements, the process is done with a high accuracy dispensing machine (500). The process starts with the unwinding of the spools into a preheat station set to approximately 50 ^& C and a series of three rollers to straighten out any crimps or wrinkles on the strip. Next, the adhesive is dispensed based on the desired volume and location. The subsequent station is a post-dispense heat cure at 100°C. The strips are kept moving along the machine through a set of motorized rollers. There is a cooling station where multiple fans are used to cool down tine strips before the final step, which is the spool rewinding. The knitted bundles are then measured to the desired length and cut into strips.

In an embodiment, the knitted strip 600a before overmoulding and die knitted strip 600b after overmoulding is shown in Fig. 6a & 6b in accordance with an embodiment of the invention. The strips are overmoulded at both ends. In an embodiment, a moulding machine (700a, 700b, 700c) made up of an injection unit (701) and a clamping unit (702) is shown in Fig. 7a. The injection unit (701) has a feed hopper (710) and a barrel (720). The barrel (720a) consists of an injection moulding screw (730) and heaters (740). The clamping unii (702) has a mould made up of two platens 750 (750a, 750b); a stationary platen (750a) and a movable platen (750b The thermoplastic polyester elastomer (TPE) is ted into the hopper (710) of the injection moulding machine. The injection moulding screw (730) melts the plastic and continuously injects it into the mould. I¾e heater bands (740) around the barrel (720) help the injection moulding screw (730) maintain an evert temperature. The machine includes a nozzle (725) connected to the clamping unit (702). The clamping unit 702 consists of two platens 750 (750a, 750b) that are clamped at a pressure ranging between J 50 M Pa and 250 MPa for 10 s to 50 s during the overmoulding. The brush body portion is placed on the platen and clamped while the cavity (760) at both ends are filled with the molten thermoplastic material.

In an embodiment, as shown in Fig 7b, the clamping unit 702 for the brush strips with a 90 ^c radial protrusion from the carrier is provided. Further in Fig. 7c the clamping unit 702 tor the brush strips with a 65° radial protrusion from the carrier is provided. The overmolded body portion is removed after the thermoplastic material solidifies upon cooling down. The moulding press includes top warp yarn (770a, 770b), bottom warp yarn (780a, 780b), brush sheet (790), selvedge (795a, 795b;. in an embodiment, the body portion 800 of the brush is slit into two as shown in Fig 8 and the bristles are trimmed to the desired height to form the brush.

The completed brushes are assembled into the brush bar by inserting the brush strip carriers into the grooves on the brush bar. After ail the assembly steps are completed, the brush bar dimensions are checked and a balancing test is performed. The rotational balance of the fully assembled brush bars is tested to segregate parts that could potentially cause unwanted noise and vibrations when the vacuum cleaner is operating. The manufacturing flow described above was used io produce the current embodiments. The embodiments differ in specific features from the prior art, such as embedded knitting yarns, blend feature at the carrier or oblique angled bristle tufts. In an embodiment, the brush stiffness as measured by the deflection capability determined by the bristle material, diameter and length.

in another embodiment, the bend recovery and fatigue resistance of the bristles when exposed io operating conditions such as the surrounding temperature and humidity determine the performance of the brushes.

In one embodiment, the brush sweep angle determines the force applied on the debris and the carbon fiber filaments electrostatically discharge debris and consequently improve the sweeping action.

In one embodiment, the brush (900a, 900b, 900c) includes a brush portion (901a, 901b, 901c) where bristles extend from the carrier (902a, 902b, 902c) as shown in Fig 9a, 9b &9c. The bristles are provided as radially extending 90 degree (as shown in Fig. 9a) from carrier (902a), brush with blend feature (980a, 980b) and radially extending 90 degree from carrier (902b) and brush with bristles extending 65 degree from the carrier C902ej. 3¾e brush provides brush strip bristle tufts (910a, 910b, 910c) with bristle tip (905a, 905b, 905c) protruding radially upwards from the brush bar at approximately 90 degrees with a partially embedded top warp (920a, 920b, 920c ) and fully embedded bottom warp (930a, 930b, 930c) in the carrier (902a, 902b, 902c). The brush includes selvedge (940a, 940b, 940c), a lip (950a, 950b, 950c), a body (960a. 960b, %0c) and a base (970a, 970b, 970c). In an exemplary embodiment, the brush (900b) includes a brush portion 901b where bristles radially extend 90 degrees from the carrier 902b with the blend feature (980a, 980b) added to the carrier 902b as shown in Fig 9b.

In yet another embodiment, the brush bristles radially extend 65 degrees from the carrier 902c as shown in Fig 9c.

In an exemplary embodiment, the brush 900c includes brush bristles radially extending 65 degrees and having blend feature. The partially embedded warp (920a, 920b. 920c) and fully embedded warp (930a, 930b, 930c) are a critical feature of the construction. In an advantageous aspect- it increases the retention strength of the bristles. The embedded yarn or yarns is anchored within the carrier. As a result, the weft is held in place by the enveloping plastic carrier and the embedded knitting yarns.

In another advantageous aspect, the embedded yarn acts as a stopper to prevent the overmoulding compound from seeping to the weft to from flashes. Flashes are a reliability problem. The bristle tufts would be hardened by the plastic compound, reducing the brush strip deflection capability. Overmoulding embedded yarns requires precise mould tooling capability- because the warp forms bulges across the knitted filament body.

In an embodiment, the brush strip length is approximately 228 mm and the height is approximately 9.80 mm. The distance from the tip of the top warp to the selvedge is approximately 4.00 mm, and the distance from the tip of the bottom warp to the selvedge is approximately 2.50 mm. in an embodiment, the bristles are made from either nylon or carbon fiber. Bristles made of nylon have a filament diameter of approximately 0.10 mm. Bristles made of carbon fiber have a filament diameter of approximately 7.00 mm. In an embodiment, the base length is approximately 4.70 mm, and the base height is approximately 1.00 mm. The body length is approximately 2.40 mm and the body height is approximately 2.40 mm.

In an embodiment as shown in Fig 10a, an assembly 1000a of brush strip is protruding radially outwards from the brush bar at 90° radial angle. The brush includes brush bar 1010a with 90 degree bristle tufts 1020a, brush strips (1030a, 1040a, 1060a). The brush strips (1030a) including a leading surface ( 1032a) and atailing surface (1034a). The brush strips (1040a) includes a body portion (1042a) and base (1044a). The brush strip (1050a) includes groove (1060a).

For the brush with a blend feature at the top, the brush strip is modified for an updated model to prevent premature filament drop-off. The blend feature enables the bristles to flex more upon contact with the cleaning surface. The radius of the blend at the channel opening is approximately 0.5 mm. The blend is an important feature because it enhances the bend recovery. The mould design and manufacturing of the overrnoulding process is critical because of the precision required for the blend radius.

The brush strip is protruding radially upwards from the brush bar at approximately 90 degrees with stitching/knitting yarn 1 and stitching / knitting yarn 2 embedded in the carrier.

The embedded stitching yarn is a critical feature. Embedding the stitching yarn within the carrier increases the retention strength of the bristles. The strength of the weft is derived from two structures; the embedded knitting yarns that is anchored within the carrier and the enveloping plastic carrier that acts as a buttress. The mould design and manufacturing of the overrnoulding process is difficult because of the height difference between the weft and the warp. If not executed correctly, it would lead to defective material flow and quality problems at overrnoulding.

In an embodiment as shown in Fig 10b, an assembly 1000b of brush strip with bristles oriented at an oblique angle of 65° for a wider sweep angle is provided. The brush includes brush bar (1010b) with 65degree bristle tufts (1020b), brush strips (1030b. 1040b, 1060b). The brush strips (1040a) includes a body portion ( 1042b) and base (1044b). The brush strip (1050b) includes groove (1060b).

The brush strip is protruding radially outwards from the brush bar at approximately 65° with the top warp partially embedded and bottom warp completely embedded in the carrier. The carrier strip length is approximately 239.70 mm.

In an embodiment, the base length is approximately 9.90 mm, and the base width is approximately 1.00 mm. The body length is approximately 6.00 mm and the total carrier height is approximately 2.82 mm at one side and approximately 3.08 mm at another side.

Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.

As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its essential characteristics. The present embodiments is therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and ail changes which come within therefore intended to be embraced therein.