GB2111614A

GB2111614A - Belt pulley with a variable outer diameter

Info

Publication number: GB2111614A
Application number: GB08235592A
Authority: GB
Inventors: Herbert Schonmeier
Original assignee: Jagenberg Werke AG
Current assignee: Jagenberg Werke AG
Priority date: 1981-12-17
Filing date: 1982-12-14
Publication date: 1983-07-06
Also published as: IT8224736A0; FI823049A7; JPS58106256A; FR2518689A1; IT8224736A1; FI823049A0; DE3150030C1; FI823049L; BR8204532A; IT1191130B

Abstract

The pulley consists of a tubular support member 1 to be attached to a shaft, on which support member, for common rotation with the latter, segments are arranged which are able to move in the same axial position radially with respect to the support member. Belts 19 are guided over the support member 1 and comprise a bore located at an acute angle with respect to the axis of the support member, through which bore a guide bolt 13 passes with an exact fit, which guide bolt is mounted on both sides on a sleeve 3 able to move axially on the support member. Each guide bolt is connected rigidly to the sleeve 3 on both sides by screws 14, 15 extending approximately radially. <IMAGE>

Description

SPECIFICATION Belt pulley The invention relates to a belt pulley with a variable outer diameter, consisting of a tubular support member to be attached to a shaft, on which support member, for joint rotation with the latter, segments are provided which are able to move in the same axial position radially with respect to the support member, over which segments belts are guided and which comprises a bore located at an acute angle with respect to the axis of the support member, through which bore a guide bolt passes with an exact fit, which is mounted on both sides on a sleeve able to move axially on the support member.

Such commercially available belt pulleys have a variable outer diameter, in order to be able to vary the transmission ratio of the belt drive in the assembled state. Conventional belt pulleys with a variable diameter have the following drawbacks caused by their construction. The guide bolts located obliquely in the belt pulley, which form an inclined plane, along which the expanding segments vary their position in the radial direction, upon axial displacement of the guide bolts, in which case they are guided in an axially fixed manner, are mounted in bushes at both ends. Like the bore in the segment, the bores in the bushes must be drilled obliquely with respect to the axis of the belt pulley in order to receive the guide bolt.

In order to be able to maintain the closest possible tolerances, all the bores must be machined exactly in alignment with each other. The guide bolt needs no clearance either in the bearing nor in the bore of the expandable segment. This necessitates expensive precision machining. Even the smallest variations lead to premature wear in the region of the guide section on the bolt or of the bore surface of the expandable segment. It is a further drawback that dimensional differences caused at the time of manufacture cannot be corrected at the time of assembly.

Now it is the object of the invention to construct the above-mentioned type of belt pulley in an improved manner so that manufacture is simplified and thus made more economical and at the same time a compensation for small tolerance variations in the inclined position of the bore in the expandable segment and the guide bolt passing therethrough is facilitated at the time of assembly.

A belt pulley with the features of the claims is proposed in order to achieve this object.

The belt pulley according to the invention provides the advantage that at the time of assembly, small tolerance variations in the inclined position of the guide bolt and the bore in the expandable segment can be compensated for in a relatively simple manner by placing spacer members below the contact surfaces at the ends of the guide bolt before it is screwed in an approximately radial direction to the sleeve able to move axially on the support member. Premature wear on the contact surfaces is simultaneously prevented as a result of non-exact guidance of the bolt in the bore in the expandable segment.

The invention is described in detail with reference to the drawings: Figure 1 shows one embodiment of the belt pulley according to the invention in one position, in longitudinal section and Figure 2 shows the latter in a second position, Figure 3 is a cross-section on line A-B of figure 1 and Figure 4 is a section on line C-D of figure 2.

The belt pulley consists of the tubular support member 1, which is attached to a shaft or spindle (not shown) for its rotary drive. Attached on both sides to the support member 1 is the housing 2, which can be divided centrally in a plane arranged at right angles to the axis of the support member 1.

A sleeve 3 is arranged inside the housing 2 by means of an adjusting spring 4 for rotary entrainment and it is able to move axially. The axial displacement of the sleeve 3 takes place with the assistance of a spindle 6 able to be rotated by means of a hand wheel 5, which spindle 6 is mounted in a fixed manner in the housing cover 7.

The spindle 6 engages by means of a screwthread with a plate 8 connected to the sleeve 3.

Attached to the ends of the sleeve 3 are spacer rings 9, 10, on which bevelled contact surfaces 11, 12 are provided. Bearing on these contact surfaces 11, 12 are a plurality of guide bolts 13 distributed uniformly on the periphery of the support member 1, in an inclined position with respect to the axis of the support member 1, with flat faces on their end sections. The guide bolts 11 are fixed by way of the spacer rings 9, 10 to the axially displaceable sleeve 3, by screws 14, 1 5 extending approximately radially. By inserting spacer members 1 6, the inclined position of the guide bolts 11 can be varied.The guide bolts 11 pass with an exact fit through an inclined bore 17 in the radially movable segments 18, the segments 18 are guided in an axially fixed manner through openings in the outer periphery of the housing 2. The belt 19 wraps around the segments 1 8.

By actuating the hand wheel 5 and by the related rotation of the spindle 6, the sleeve 3 is moved axially on the support member 1. The guide bolts 13 also move axially with the sleeve 3 with respect to the support member 1, as shown by a comparison of figures 1 and 2. At the time of axial displacement of the guide bolts 13, the segments 18 guided by the latter in the bore 17 move in radial direction with respect to the support member 1. Figures 1 and 2 show respectively the end positions of such an axial displacement of the guide bolts 1 3 and the corresponding radial end position of the segments 1 8 and 1 9. The periphery of the radial displacement of the segments 1 8 is determined on the one hand by the inclined position of the guide bolts 13 and on the other hand by their length. The degree of radial displacement of the segments 18 can be influenced by selection of these two parameters.

Claims

1. Belt pulley with a variable outer diameter, consisting of a tubular support member to be attached to a shaft, on which support member, for common rotation with the latter, segments are arranged which are able to move in the same axial position radially with respect to the support member, over which belts are guided and which comprise a bore located at an acute angle with respect to the axis of the support member, through which bore a guide bolt passes with an exact fit, which guide bolt is mounted on both sides on a sleeve able to move axially on the support member, wherein each guide bolt is connected rigidly to the sleeve on both sides by screws extending approximately radially.

2. Belt pulley according to claim 1, wherein the guide bolt is attached to the sleeve by way of spacer rings.

3. A belt pulley substantially as herein described with reference to and as illustrated in the accompanying drawings.