GB2158914A

GB2158914A - Improvements relating to pulleys

Info

Publication number: GB2158914A
Application number: GB08412753A
Authority: GB
Inventors: Hans Wessel
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-05-18
Filing date: 1984-05-18
Publication date: 1985-11-20
Also published as: SE438248B; FR2564723A1; SE8402612D0; CH664078A5; SE8402612L; GB2158914B; FR2564723B1; GB8412753D0

Abstract

A toothed pulley (5) is made in two parts (6, 7) and partially embedded in the moulded cylinder (2) of a roller brush (1). Each part has a flank, which together provide lateral guide flanges for a toothed belt which drives the brush, and mutually engaged ring portions (8, 10). The outer portion (8) has the teeth integrally formed on its outer surface while its inner surface (11) positively engages the outer surface (12) of the inner portion (10). These engaging surfaces may be coned at a shallow angle and rely on frictional grip, or they may have intermeshing teeth. The inner portion (10) may also have a key formation (14, 15) to grip the cylinder. <IMAGE>

Description

SPECIFICATION Improvement relating to pulleys The invention relates to pulleys and is primarily concerned with drive pulleys for cylindrical brushes on vacuum cleaners and carpet-beating machines.

The majority of such cylindrical brushes are driven either by circular section or flat belts, or by gear wheels. More recently, toothed belts have been introduced. However, the attachment of the toothed belt pulley to the cylinder presents problems, because the brushes run at high speeds of the order of 5000-8000 revs/min. They must therefore be very well balanced to run true, for example with maximum unbalance of 10g/min.

In the case of wooden cylinders, the desired accuracy can be achieved only by wasteful and expensive counterbalancing, and so dimensionally more stable materials, especially thermoplastics foamed to reduce weight, are better. However, such a body is relatively soft and is not very wear-resistant. But the drive pulley must have better stability, and so is preferably manufactured from a high-grade thermoplastics material of the polyamide series. In other words, it cannot be formed integrally with the cylinder.

Various ways of fastening toothed or standard belt pulleys have been tried. For example, a pulley may be fixed to the cylinder body by means of a press fit, or it may be made in two halves which are brought together around the cylinder and seamed by adhesive.

Standard belt pulleys can be fixed satisfactorily in this way, but toothed pulleys require flanges flanking the teeth to confine and guide the belt, and this leads to manufacturing problems. Such pulleys have generally been manufactured as a moulding only by tools having several movable segments, or by the double injection-moulding process. This means high tool costs, which are reflected in the expense of such parts.

According to the present invention there is provided a drive pulley for a cylindrical brush, the pulley comprising two annular members co-axially fitted together, the first member having a first flank and a first annular portion extending axially therefrom with external gear teeth, and the second member having a second flank and a second annular portion extending axially therefrom, the second annular portion engaging within the first annular portion so that mutual rotation is prevented.

In one preferred form, the engaging surfaces of said portions are coned, the angle being of the order of 1:1 00, with frictional resistance preventing mutual rotation.

Alternatively, the engaging surfaces may have intermeshing teeth.

In order positively to prevent the pulley slipping around on the brush cylinder, the second annular portion may have an internal formation which keys into the cylinder, this formation preferably being an annular rib with recesses.

For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is an axial section of a cylindrical brush, and Figure 2 is an enlarged detail of Fig. 1, showing part of a toothed belt pulley.

A rotary brush 1 has a cylindrical body 2 made of foamed thermoplastics material, and it rotates on stub axles 3 embedded at both ends. Bunches of bristles 4 are arranged spirally over the cylindrical surface.

A toothed belt pulley 5 at an intermediate point along the length of the body 2 provides the drive, the body 2 being moulded to it as described below. The pulley is made in two parts generally referenced as annular members 6 and 7. The member 6 includes a ring portion 8 extending in an axial direction from its flank 9 and being formed with external gear teeth. The other member 7 has an inner ring portion 10 extending in an axial direction from the radially inner portion of its flank, which frictionally fits within the portion 8. The latter has a coned inner surface 11 which matches a coned outer surface 12 of the portion 10, the incline of the cone (referenced 13) being of the order of 1:100. This is much exaggerated in the drawing.

When the members 6 and 7 have been pressed axially together, completing the pulley with guide flanges on both sides of the teeth, it is fitted into the mould for producing the cylinder body 2. In order to prevent the pulley 5 slipping around the body 2, an annular rib 14 projecting inwardly from the portion 10 provides a key by means of recesses 15 whose shape, looking in the axial direction, is also shown in Fig. 2.

Instead of relying on the frictional engagement of the coned surfaces 11 and 12 and the adhesion of the material of the body 2 to the inner surface of the member 6, the ring portion 8 may be internally toothed to mate with corresponding outer toothing on the inner portion 10.

The toothed belt pulley 5 described above can easily be finished and assembled, and the two components are easy to remove from their moulds. In spite of there being two separate parts, the tooling costs are lower than for the tools mentioned above with sliding segments or for the double injectionmoulding process.

1. A drive pulley for a cylindrical brush, the pulley comprising two annular members co-axially fitted together, the first member

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvement relating to pulleys The invention relates to pulleys and is primarily concerned with drive pulleys for cylindrical brushes on vacuum cleaners and carpet-beating machines. The majority of such cylindrical brushes are driven either by circular section or flat belts, or by gear wheels. More recently, toothed belts have been introduced. However, the attachment of the toothed belt pulley to the cylinder presents problems, because the brushes run at high speeds of the order of 5000-8000 revs/min. They must therefore be very well balanced to run true, for example with maximum unbalance of 10g/min. In the case of wooden cylinders, the desired accuracy can be achieved only by wasteful and expensive counterbalancing, and so dimensionally more stable materials, especially thermoplastics foamed to reduce weight, are better. However, such a body is relatively soft and is not very wear-resistant. But the drive pulley must have better stability, and so is preferably manufactured from a high-grade thermoplastics material of the polyamide series. In other words, it cannot be formed integrally with the cylinder. Various ways of fastening toothed or standard belt pulleys have been tried. For example, a pulley may be fixed to the cylinder body by means of a press fit, or it may be made in two halves which are brought together around the cylinder and seamed by adhesive. Standard belt pulleys can be fixed satisfactorily in this way, but toothed pulleys require flanges flanking the teeth to confine and guide the belt, and this leads to manufacturing problems. Such pulleys have generally been manufactured as a moulding only by tools having several movable segments, or by the double injection-moulding process. This means high tool costs, which are reflected in the expense of such parts. According to the present invention there is provided a drive pulley for a cylindrical brush, the pulley comprising two annular members co-axially fitted together, the first member having a first flank and a first annular portion extending axially therefrom with external gear teeth, and the second member having a second flank and a second annular portion extending axially therefrom, the second annular portion engaging within the first annular portion so that mutual rotation is prevented. In one preferred form, the engaging surfaces of said portions are coned, the angle being of the order of 1:1 00, with frictional resistance preventing mutual rotation. Alternatively, the engaging surfaces may have intermeshing teeth. In order positively to prevent the pulley slipping around on the brush cylinder, the second annular portion may have an internal formation which keys into the cylinder, this formation preferably being an annular rib with recesses. For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is an axial section of a cylindrical brush, and Figure 2 is an enlarged detail of Fig. 1, showing part of a toothed belt pulley. A rotary brush 1 has a cylindrical body 2 made of foamed thermoplastics material, and it rotates on stub axles 3 embedded at both ends. Bunches of bristles 4 are arranged spirally over the cylindrical surface. A toothed belt pulley 5 at an intermediate point along the length of the body 2 provides the drive, the body 2 being moulded to it as described below. The pulley is made in two parts generally referenced as annular members 6 and 7. The member 6 includes a ring portion 8 extending in an axial direction from its flank 9 and being formed with external gear teeth. The other member 7 has an inner ring portion 10 extending in an axial direction from the radially inner portion of its flank, which frictionally fits within the portion 8. The latter has a coned inner surface 11 which matches a coned outer surface 12 of the portion 10, the incline of the cone (referenced 13) being of the order of 1:100. This is much exaggerated in the drawing. When the members 6 and 7 have been pressed axially together, completing the pulley with guide flanges on both sides of the teeth, it is fitted into the mould for producing the cylinder body 2. In order to prevent the pulley 5 slipping around the body 2, an annular rib 14 projecting inwardly from the portion 10 provides a key by means of recesses 15 whose shape, looking in the axial direction, is also shown in Fig. 2. Instead of relying on the frictional engagement of the coned surfaces 11 and 12 and the adhesion of the material of the body 2 to the inner surface of the member 6, the ring portion 8 may be internally toothed to mate with corresponding outer toothing on the inner portion 10. The toothed belt pulley 5 described above can easily be finished and assembled, and the two components are easy to remove from their moulds. In spite of there being two separate parts, the tooling costs are lower than for the tools mentioned above with sliding segments or for the double injectionmoulding process. CLAIMS

1. A drive pulley for a cylindrical brush, the pulley comprising two annular members co-axially fitted together, the first member having a first flank and a first annular portion extending axially therefrom with external gear teeth, and the second member having a second flank and a second annular portion extending axially therefrom, the second annular portion engaging within the first annular portion so that mutual rotation is prevented.

2. A drive pulley as claimed in Claim 1, wherein the engaging surfaces of said portions are coned, and frictional resistance prevents mutual rotation.

3. A drive pulley as claimed in Claim 2, wherein the cone angle is of the order of 1:100.

4. A drive pulley as claimed in Claim 1, wherein the engaging surfaces of said portions have intermeshing teeth to prevent mutual rotation.

5. A drive pulley as claimed in any pre ceding claim, wherein the second annular portion has an internal formation for keying into a brush roller body.

6. A drive pulley as claimed in Claim 5, wherein said formation is an annular rib with recesses.

7. A drive pulley substantially as hereinbefore described with reference to the accom panying drawing.

8. A cylindrical brush fitted with a drive pulley as claimed in any preceding claim.

9. A vacuum cleaner fitted with a roller as claimed in any preceding claim.

9. A brush as claimed in Claim 8, wherein the brush has a cylindrical body moulded in foamed thermoplastics material, and the pul ley is partially embedded in its cylindrical surface during the moulding process.

10. A vacuum cleaner fitted with a brush as claimed in Claim 8 or 9.

CLAIMS Amendments to the claims have been filed, and have the following effect: Claims 1 to 10 above have been deleted or textually amended.

New or textually amended claims have been filed as follows:

1. A brush roller for vacuum cleaners comprising a cylindrical body of foamed plastics material with bristles inserted therein, and a toothed pulley coaxially fitted to the body, the pulley comprising two annular members co-axially fitted together, the first member having a first flank and a first annular portion extending axially therefrom with external gear teeth, and the second member having a sec ond flank and a second annular portion ex tending axially therefrom, the second annular portion engaging the first annular portion and the cylindrical body so that mutual rotation is prevented.

2. A roller as claimed in claim 1, wherein the second annular portion has an internal formation for keying into said body.

3. A roller as claimed in claim 2, wherein said formation is an annular rib with recesses.

4. A roller as claimed in claim 1, 2 or 3, wherein said annular portions interengage by coned surfaces, frictional resistance preventing mutual rotation.

5. A roller as claimed in claim 4, wherein the coned angle is of the order of 1:1 00.

6. A roller as claimed in claim 1, 2 or 3, wherein said annular portions interengage by intermeshing teeth which prevent mutual rotation.

7. A roller substantially as hereinbefore described with reference to the accompanying drawing.

8. A roller as claimed in any preceding claim, wherein the pulley is partially embedded in the cylindrical surface of said body during the moulding thereof.