GB2215807A

GB2215807A - Toothed gear wheel

Info

Publication number: GB2215807A
Application number: GB8902669A
Authority: GB
Inventors: Herbert Schneider; Walter Stumpf; Ulrich Bertram
Original assignee: Pierburg GmbH
Current assignee: Pierburg GmbH
Priority date: 1988-02-08
Filing date: 1989-02-07
Publication date: 1989-09-27
Also published as: IT1232202B; DE3829367A1; IT8947594A0; GB8902669D0; FR2626952A1

Description

0 7 TOOTBED WIBEEL The invention relates to a toothed wheel, particularly

for synchronous gearwheel drives for rotary-piston superchargers.

In the operation of known rotary-piston superchargers driven through synchronous gearwheel drives, oscillations caused by the pulsating pumping action of the supercharger, for example when operating under load at low engine speeds, brings the flanks of the driving and driven teeth of the gearwheels to strike against each other intermittently, producing noisy chattering in the drive.

The intention in the invention is to construct a gearwheel drive of this kind in such a way that noiseless transmission is possible.

The problem is solved by the characteristics claimed in Claim 1. Advantageous further developments are described in the characteristics of the subsidiary claims.

Accordingly, this invention provides a toothed wheel, particularly for the synchronous driving of rotary-piston superchargers, which is characterised in that the toothed wheel consists of two individual tooth sets resiliently joined together side by side and angularly displaced, relative to each other, by a specified angle of rotation. Elastomeric bodies or metal springs, or both in combination, may be employed to join the offset teeth.

The new toothed wheel has the advantage that radial play between the teeth of the meshing gearwheels is reduced to a minimum. This is particularly important in synchronised gearwheel drives for rotaiy-piston superchargers, which pump the ' medium in a pulsating manner, particularly when under load at low engine speeds. The teeth of the drive are loaded intermittently at high frequencies, first in the one direction of rotation, then in the other, and in the known drives this produces a loud chattering noise.

2 By way of example, a number of embodiments of toothed gear wheel according to the invention are shown in the accompanying drawings in which:

Figwe 1 is a cross section through a double toothed wheel consisting of two individual toothed wheels joined together.

Figum shows a further example of two toothed wheels joined together.

Figure 3 is a front view of a portion of the double toothed wheel.

Figure is a front view of another example of a toothed wheel consisting, in this case, of a toothed wheel with, joined resiliently to it, a toothed ring.

Figgre 5 is a cross section through a portion of the toothed wheel of Figure 4.

The double toothed wheel 1 shown in cross section in Figure 1 consists of two individual tooth sets 2 and 3 joined together resiliently by a layer of elastomeric material 7 injected, or vulcanised, into drilled holes 5, or into recesses 6 (Figure 2). i As shown in Figure 3, the teeth of the two sets are off-set by a small angle of rotation 4 with respect to each other. The number of drilled holes 5, or recesses 6, and their sizes, is selected to agree with the flexibility of the elastomeric layer and with the shearing stresses acting on the teeth, relatively to each other.

Alternatively, the two tooth sets can, if desired, be joined together by plugs 8 (Figure 3) of an elastomeric material, forced into drilled holes 5.

In the example of Figure 2 there is, joined to a toothed wheel 1, a toothed rim 10' whose teeth are off-set by the small angle of rotation 4 with respect to the teeth of the toothed wheel 11. The rim 10 is joined resiliently to the wheel 11 by a layer of elastomeric material injected, or pressed-in, or vulcanised-in, into drilled holes 5, or into recesses 6, in the two parts 11 and 10.

3 Figure 4 is front view of another example of a toothed wheel I I (compare the cross section of Figure 5) joined resiliently to a toothed rim 10. And again the two sets of teeth are displaced, relative to each other, by the small angle of rotation 4 represented in Figure 3. In this example the two parts I I and 10 are joined resiliently together by a ring, or layer 7, of elastomeric: material injected, or vulcanised-in, into an annular recess 12 in the toothed wheel 11. The resilient jointing layer 7 is stiffened, in this example, by two opposite pairs of leaf springs 13 inserted, before the injection or vulanising, into the recesses 14 in the toothed wheel 11 and into recesses 15 of the toothed rim 10.

Each annular recess 14 has a wider portion 16, near the annular recess 12, to give the inserted leaf spring 13 a limited freedom to flex sideways.

The inserted leaf springs 13, resiliently reinforcing the elastomeric layer 7, maintain the pre-stressed off-set angle 4 between the two sets to teeth, even during operation at high temperatures. The leaf springs are usually of metal.

If desired, more than four leaf springs can be used, or less than four. But there should be at least one pair, the two springs positioned diametrically opposite each other.

Furthermore, if desired, other kinds of spring can be used, depending on constructional convenience. Finally, if desired, only springs can be used, without any elastomeric layer.

It is preferable to position the pairs of wheels 2, 3, of the wheels and rims 11, 10, axially next to each other, at least where the teeth are, to prevent a shoulder from developing during the working-in of the separate narrow teeth of the meshing driving or driven wheels.

The invention can, of course, be applied in other kinds of machines using meshing gearwheel drives.

4

Claims

L" Toothed wheel, particularly for the synchronous driving of rotarypiston superchargers, characterised in that the toothed wheel (1 to 9) consists of two individual tooth sets (2 and 3) or (11 and 10) resiliently joined together side by side and angularly displaced, relative to each other, by a specified angle of rotation (4).
2. Toothed wheel as claimed in Claim 1, characterised in that the two tooth sets are joined together by an elastomeric layer (7) injected into recesses (6 or 12) in members carrying the respective tooth sets.
3. Toothed wheel as claimed in either of Claims 1 or 2, characterised in that the two sets (2 and 3) or (11 and 10), or members carrying the respective tooth sets, are bonded to the elastomeric layer by vulcanising.
4. Toothed wheel as claimed in Claim 1, characterised in that the two tooth sets are joined together by means including elastomeric plugs (8) forced into drilled holes (5) in members carrying the respective tooth sets.
5. Toothed wheel as claimed in any one of Claims 1 to 4, characterised in that in addition to the elastomeric layer (7) joining the members carrying the respective offset tooth sets (2 and 3) or (11 and 10) together, there are further elements (13) in recesses (14, 15) in the said members for reinforcing the resilientjunction of the members.
6. Toothed wheel as claimed in Claim 5. characterised in that the elements for re-inforeing the junction consist of at least two springs, particularly leaf springs which may be of metaL
7. Toothed wheel as claimed in any one of Claims 1 to 6, characterised in that the two offset tooth sets (2, 3) or (11 and 10) rest in axial contact with each other, at least in the region of the teeth.
8. A toothed gear wheel substantially as described with reference to any one or more of the figures in the accompanying drawings.

Published 1989 at The Patent Mce, State House. 68.,71 High Holborn, London WC1R 4TP. Purther copies maybe obtained from The Patent 0Mce. Wee Branch, St Mary Cray, Orpington, Kent BR5 3RD, Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1187