In practice, changing a brush during work is preferably avoided. It requires, for example, going down and up the stairs more often; it takes more time and the chances of leaking during the exchange are higher. Also, the brush temporarily not used may dry in.

From the state of the art, solutions are known whereby one and the same brush can be used both for larger surfaces and for finer work. The principle is for a finer brush to be shdably received within the sleeve circumference of a larger or wider brush. To secure two possible operative conditions (retracted and extended), a setting means such as a screw or clip is used which fixes the smaller brush relative to the larger brush.

Such a multifunctional brush has many advantages, the most important one being that fewer brushes are needed. Instead of wide and narrow brushes, now only one brush type is needed. It saves working time because now there is no need to change brushes during work. Costly paint is thus saved. And less cleaning spares the environment. A smaller brush will hereinafter be further referred to as "auxiliary brush" and a wider brush as "main brush".

In retracted condition, the paint for an auxiliary brush is supplied by the bristles of the main brush. The bristles of the auxiliary brush in the retracted condition are fully enclosed by the bristles of the main brush and take up the latter 's paint.

In overarm painting, with the auxiliary brush in extended condition, paint runs down, which is received by the bristles of the main brush. Thus, in the use of the auxiliary brush, leaking and soiling of the handle of the brush will tend to occur less.

The publication JPH0549511A shows a multifunctional brush with a flat main brush where eccentrically through its handle and sleeve a recess has been made through which the auxiliary brush is movable, being fixable with a clamping sliding clip on the side of the handle.

US 2816305A proposes a flat main brush in which centrally within its wooden handle, continuing into the sleeve, a recess has been made in which an auxihary brush is received. It is slidable within the housing of the main brush and fixable with a turning button.

The state of the art as outlined above has a number of inherent disadvantages. The object of the present invention is to solve the

disadvantages of the state of the art and moreover to provide an improved multifunctional brush which in practice is better usable, simpler, more reliable in operation and relatively inexpensive to produce. The invention achieves this object by providing a brush of the type described in the preamble, with the characterizing features of claim 1 and further claims, as is explained hereinbelow.

In the solutions known from the state of the art, sliding of the auxiliary brush in the main brush causes a sliding of their respective bristles relative to each other in the axial (length) direction of the brush. The stiffness of the bristles in that direction can lead to their sticking together so that upon sliding, a curling, bending or even buckling of bristles occurs. This increases the chance of paint splashes (as a result of bristles suddenly coming loose) and may even damage the bristles by doubling. This is not beneficial to the life span of the brush.

According to claim 1 of the invention, the through-hole in the main brush and the sleeve of the auxiliary brush have a fitting cylindrical cross section. This means that the auxiliary brush is not only axially but also rotationally movable within the main brush. This makes it possible for the user, during operation, to move the auxiliary brush forwarcUy or backwardly with a rotary movement. As a result, the bristles also move tangentially relative to each other, so that bristles sticking together or bending and then coming loose abruptly will occur less and there is less chance of splashing or damage.

Claim 2 offers an alternative or additional feature for the same problem. By providing main brush and auxiliary brush with thread and groove for a mutual threaded connection, during operation, by the user, a rotation of the handle relative to the main brush is converted into an axial movement of the auxiliary brush, in which manner the auxiliary brush can be moved to an operative condition. The rotary movement ensures that the bristles move tangentially, as described above, and, as a result of the screw thread, shift simultaneously. In tangential direction, the bristles behave more flexibly: they move more easily along with each other, and detach from each other more gradually than upon movement in axial direction alone.

The threaded connection provides a same effect and problem solution as described for the feature of claim 1, with the additional advantage that the user during operation only needs to rotate and does not additionally need to slide the auxiliary brush in axial direction, which is of benefit to the convenience of use. Manual sliding of the auxiliary brush in axial direction during operation may proceed jerkily, especially upon initial movement from the rest condition. This may cause unwanted paint splashes, especially if the sliding connection, as a result of previously caked-on paint, runs stiffly or is stuck and suddenly comes loose when force is applied.

The feature of claim 2 has as an effect that when during operation the auxiliary brush is rotated relative to the main brush, the thus-induced shift of the auxiliary brush in axial direction is gradual.

The pitch of the threaded connection is an important variable: the lazier the screw thread, the more retardation arises in the axial sliding movement and the greater the effect of the feature. A screw thread of lazy configuration (<45 degrees) has as an effect that the rotary movement, due to the lever action, yields a slower movement and greater shearing force in axial direction.

For example, in the case where caked-on paint has led to a sticky auxiliary brush, the feature of claim 2 ensures that the chance of the auxiliary brush slipping loose suddenly are low, which ensures that upon adjustment of the auxiliary brush no paint splashes are caused. A solution whereby an auxiliary brush is received in a slot or hole in the main brush implies there is clearance space: space between the slot or hole in the main brush and the circumference of the auxdiary brush which is movable therein. This space, as a result of capillary action, wdl draw in paint, which can provoke leakage of paint. This will be manifest especially in overarm painting, as a result of gravity.

The invention counteracts this with the threaded connection which is proposed as a measure in claim 2. By providing the main brush and auxiliary brush with thread and groove, respectively, there is formed, throughout the length of thread and groove, a contact surface between the cylindrical hole and the sleeve of the auxiliary brush. This contact surface reduces the clearance considerably and this prevents paint flowing through or being drawn in. The lazier the screw thread, the more successive threads it will have. As a result, the sealing contact surface between thread and groove in the connection between main brush and auxiliary brush is larger and the sealing effect is stronger. This feature effectively counteracts paint flowing through, and has a retarding effect on leak-through of paint. The solution known from the state of the art contains relatively many parts; is hence less reliable in operation, more expensive to produce and also more difficult to clean than a simpler type. This can entail higher consumption of cleaning agent and more impact on the environment.

The invention seeks to propose an operationally reliable, simplified product which can be realized with considerably less material. To that end, the invention proposes in claim 3 to make the handle portion of the auxiliary brush considerably longer than the length of the main brush.

By making the length of this handle portion of such magnitude that it can be embraced by a human hand, the handle portion of the auxiliary brush can serve as a handgrip for the whole paintbrush. The main brush is regarded as a part of the paintbrush that is to be arranged around the auxiliary brush, with the handle portion of the auxiliary brush serving as handgrip for the entire brush.

The surprising effect of this is that a handle portion for the main brush can be omitted. In other words: by this measure, the main brush with just a sleeve and bristles can suffice; there is no function for a handle portion. This results in a considerable saving of material and simpler construction in comparison with the state of the art. Every known solution for a multifunctional brush is laborious in use. A slidable auxihary brush from the state of the art experiences a hmited resistance to movement and therefore needs a fixing possibility. Without fixation, an auxiliary brush in extended condition during use will slide back rather easily under the influence of gravity or by any force on a brush part in handling the brush. For this, the state of the art proposes as a technical measure a provision for fixation. This provision, however, entails the consequence that setting requires three actions: releasing, sliding, and fixing the auxihary brush again. Moreover, the fixation possibility may easily get soiled by paint. All of this leads to additional, time-consuming operations.

The invention proposes as a measure in claim 2 a threaded connection between auxiliary brush and main brush. This feature effects a retardation (reduction) in the drive of the auxiliary brush in axial direction. The retardation is greater according as the pitch of the screw thread is smaller. If the pitch of this screw thread is of lazy configuration (less than 45 degrees), the auxiliary brush, as a result of the retarding action of the threaded connection, will experience a resistance in axial direction that counteracts movement in the through-hole of the main brush. This means that the auxihary brush will retain its position and does not need any fixation means. This makes the construction simpler, lower-cost, and easier to clean. The optimum -functioning value of the pitch must be estabhshed experimentally and also depends on the magnitude of the groove and thread profile. Recommended is a pitch between 30 and 40 degrees.

The paintbrush according to the invention can be made up of at least two detachable parts: a main brush, consisting of a sleeve and bristles, and an auxihary brush, consisting of a sleeve, bristles and handle connected thereto. During operation, the detachable parts are joined together. Handle and sleeve of the auxiliary brush may be integral, which is the preferred implementation, especially in a plastic implementation.

For cleaning, the two parts can be simply taken apart by rotating the auxiliary brush out of the main brush. The simple maintenance prolongs consumer quality and life span and saves on environmentally unfriendly cleaning agents.

The invention proposes in claim 4, as a further improvement against leaking, to provide the sleeve of the main brush with a bottom in order to provide a supporting surface and to include a sealing ring which closely fits around the handle portion of the auxiliary brush and lies on the bottom of the sleeve mentioned.

In this embodiment, the sleeve of the auxiliary brush has a greater diameter than the handle portion. The whole is preferably dimensioned such that the seahng ring is a close fit around the handle of the auxiliary brush and is also a close fit within the circumference of the through-hole in the main brush. What is thus achieved is that paint cannot, from the sleeve of the main brush, reach the bottom of this sleeve, or the hole at the lower end of this sleeve. Thus, a practically clearance-free connection is achieved between auxiliary brush and main brush, which counteracts leaking of paint during operation. In overarm painting, with any known type of brush, at some point excess paint runs down out of the bristles. The bristles gradually become saturated at the bottom, and paint flows over the edge of the sleeve in which they are received. Such leaking is inevitable if the brush is held up long. In a multifunctional brush according to the invention, moreover, upon the outwardly directed axial movement towards the extended position, paint from the surrounding bristles of the main brush is entrained, so that the saturation mentioned will occur sooner.

The invention proposes as an improvement in claim 5 to provide the sleeve of the auxiliary brush along its circumference with a leak edge which is at the top of the outer circumference of the sleeve, where the bristles extend. The diameter of the leak edge increases in the direction of the bristle surface. This feature hinders paint, at least for some time, from running over the edge of the sleeve and leaking away.

The invention will now be briefly further explained, with reference being had to the figures. The figures are for elucidation of the claims of the invention and are not intended to limit them. Only a few of all possible embodiments are shown.

Figure la: Retracted condition in cross section

Figure lb: Extended condition in cross section

Figure lc: Improvements

Figure 2: Brush variants, top plan view

Figure 3a: Groove in main brush, cross section

Figure 3b: Thread on auxiliary brush, elevational view

Figure 3c: Threaded connection in cross section

Figure 4: Sealing ring in assembly in cross section

Figure 5: Leak edge on auxiliary brush in cross section In the figures, like parts are designated with like reference numerals.

Figure la shows an assembly of a main brush 1 and an auxiliary brush 14 in a retracted operative condition in a cross section in length direction.

This is the simplest conceivable embodiment, where, according to claim 1, it is relevant that the auxihary brush 14 is movable in the through- hole 5 to achieve at least two operative conditions: retracted and extended represented in Figures la/lc and Figure lb, respectively. This is possible in that the through -hole 5 and, movable therethrough, the corresponding part of the sleeve 15 and the handle portion 18 of the auxiliary brush in cross section have a fitting cylindrical cross section. At least the sleeve 15 should be receivable in the through-hole 5 with a close fit. Due to the cylindrical shape, the bristles 3, 16 can move relative to each other both axially and rotationally to counteract sticking of bristles.

Figure lc shows two variants to improve the operation of this simple embodiment.

A first improved variant counteracts leaking by a flexible ring 10 which is receivable with a clamping force fit in a groove 12 which is preferably provided throughout the circumference of the sleeve 15 of the auxiliary brush. The flexible ring 10 during operation moves along with the auxiliary brush 14 in the through-hole 5 and reduces the clearance therebetween, so that paint can leak through less easily.

A second improvement is a variant on the preceding one, whereby in addition to the previous feature, also the inner wall of the through -hole 5 is provided with at least one circumferential groove 13, in which a next flexible ring 11 is fittingly receivable. The groove 13 and flexible ring 11 in cooperation cause a resistance to axially directed displacement of the auxiliary brush 14 relative to main brush 1. In this way, an operative condition is fixable. Also, this feature counteracts leaking. In the embodiments shown, sleeve 15 and handle portion 18 of the auxiliary brush are configured as one whole. This is especially favorable in an implementation in plastic.

The auxiliary brush 14 in this variant can be moved into the through-hole 5 in the main brush 1 from the top or from the bottom. In a variant in which the sleeve 2 of the main brush is provided with a

supporting surface 7 on the bottom, the auxiliary brush can only be introduced from the top.

Figure 2 shows possible implementation variants of the brush with a top plan view of the bristle surface 4, 17 of both brush portions.

Possible variants include, inter alia, a non-round main brush "A" and "D" flat brush and a round brush "B" and "C" with mutually different sizes of the bristle surface of the auxiliary brush. In these implementations the auxiliary brush 14 and the through-hole 5, respectively, is positioned centrally within the body of the main brush 1.

The auxiliary brush in the preferred implementation has a centered position, because this makes for balance and hence for better seating in the hand. Eccentric placement "D", as is also known from the state of the art, may be advantageous with a flat brush, because it increases accessibility to corners.

For the purpose of even painting, it is preferred that the bristles of the auxiliary brush be fully enclosed by the bristles of the main brush.

Clearance between the bristle surfaces of the two brush parts 4, 17 should be limited as much as possible to achieve an even and well-usable bristle surface of the whole.

Figures 3a, 3b and 3c show in different elevational and cross sectional views a possible embodiment of a threaded connection between a main brush and an auxiliary brush.

The cylindrical through -hole 5 in the sleeve of the main brush 1 is provided with a groove 6, and the sleeve and the upper part of the handle portion 18, respectively, of the auxiliary brush 14 is provided with a thread 20 fitting into the groove mentioned. The whole is a rotatable fit over a length allowing a plurality of operative conditions to be achieved.

By, during operation, rotating the sleeve 2 of the main brush 1 relative to the handle portion 18 of the auxiliary brush 14, the auxiliary brush 14 moves in or out so as to achieve at least two operative conditions described above: extended or retracted.

The groove 6 continues up to at least the top of the sleeve 2 of the main brush, so that the auxiliary brush 14 is removable as a whole by rotation.

The pitch of the threaded connection is represented as the angle "a". The pitch has an effect on:

the retardation and, in consequence thereof, the occurring enhancement of the force upon the conversion of a rotary movement into a displacement in axial direction of the auxiliary brush;

the total length of the thread 20, which determines the magnitude of the sealing effect against leaking;

the extent to which the auxiliary brush 14 is rotatably movable under the influence of force exerted in axial direction. Also relevant is the size of the thread 20 and groove 6, that is, the fineness of the thread 20. The finer the thread, the more problematic cleaning and the tendency to stick in case of dried paint residues will be.

Preferred is a threaded connection between the two parts with a relatively coarse thread and a pitch of less than 45 degrees.

The optimum values of the fineness and the pitch can be

experimentally determined.

Figure 4 shows in a cross section in length direction an

implementation option of a seahng ring within an assembly of a main brush and an auxiliary brush.

The through-hole 5 is smaller in diameter on the side of the sleeve 2 of the main brush facing away from the bristles, and this smaller opening 8 is fitting for the passage of the handle portion 18, but smaller than the diameter of the sleeve 15 of the auxiliary brush 14, which in this variant is configured with a greater diameter than the handle portion 18. Through this arrangement, the sleeve 2 obtains a bottom which serves as a supporting- surface 7 for a sealing ring 22. The sealing ring 22 preferably has an outer diameter slightly greater than the inner wall of the sleeve 2, so that it is receivable with a clamping force fit. Preferably, the sealing ring 22 fits into a recess 9 for that purpose provided circumferentially in the wall of the sleeve.

The effect of the sealing ring 22 is that paint that is in the through - hole 5 of the main brush during operation is prevented from leaking away.

Figure 5 shows in perspective a possible implementation of a possible leak edge 21 within the assembly of main brush 1 and auxiliary brush 14. The leak edge 21, as an extra part, may be implemented in metal or plastic. In a preferred variant, the leak edge 21 and the sleeve 15 of the auxiliary brush are made in one piece. This is especially possible in an implementation of the sleeve 15 in plastic.

In the foregoing, the invention has been explained on the basis of exemplary embodiments represented in the figures. It will be appreciated by those skilled in the art that the invention is not limited thereto, but can also include further variants and modifications thereof.

The present invention solves a number of problems of the state of the art so as to accomplish an improved multifunctional brush.

The invention clearly provides for a need, it can be produced inexpensively and is environment-sparing because of the simple

construction and efficient application possibility.

The practical simplicity and reliabihty make a multifunctional brush according to the invention a very useful and economic tool for any painter, whether amateur or professional. All of the above-described features, alternatives and other possible implementation variants are understood to fall within the scope of the invention, as defined in the following claims.