GB2532712A

GB2532712A - Twisted tooth belt

Info

Publication number: GB2532712A
Application number: GB1419023.5A
Authority: GB
Inventors: Pattakos Manousos; Pattakos John; Pattakos Efthimios; Pattakos Emmanouel
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-10-24
Filing date: 2014-10-24
Publication date: 2016-06-01
Also published as: GB201419023D0

Abstract

A twisted tooth belt that is used in a drive system with counter rotating shafts comprising a closed loop strip having teeth on one side, wherein the loop strip is twisted in 720 degrees. In use the belt will preferably form an X shape between the two belt shafts/pulleys. In motion, the belts will preferably have the flat sides passing each other. The belts may also have a spacer or tensioner at the centre of the X shape or where the said belts pass each other in motion.

Description

TWISTED TOOTH BELT

The advantages of the tooth belts for the transmission of power (as in the final transmission of motorcycles, for instance) and for the synchronization of shafts (camshaft to crankshaft synchronization, for instance) are well known in the art: lightweight, reliable, quite, smooth, lubricant free, simple, cheap.

In the typical case, a belt having teeth at one side engages a pair of tooth belt pulleys (or tooth belt sprockets).

A limitation of this transmission: the two tooth belt sprockets (and the shafts wherein they are secured) rotate necessarily at the same direction.

In several applications the two shafts must rotate at opposite direction. For instance, in order the two crankshafts (disposed at a distance from each other) of an opposed piston engine to rotate in synchronization to each other and at the opposite direction, a tooth belt would be a better solution in replacement of a series of gear wheels or of a triad of bevel gears, etc; however the limitation of the same-direction is not allowing the use of a tooth belt.

An object of this invention is to present a new kind of tooth belt that can be used for the transmission of power between shafts rotating in opposite direction and for the synchronization of shafts rotating in opposite direction. The transmission ratio depends on the number of teeth of the sprockets used, for instance it can be 1, 2, 3.7, 0.75 etc. Fig 1(a) shows a conventional tooth belt engaging two tooth belt sprockets at 1:1 transmission ratio. The backside of the tooth belt is substantially "flat" (rid of teeth), while the front (or working) side of the tooth belt comprises teeth. Fig 1(e) shows the tooth belt of Fig 1(a) after the removal of the sprockets.

In Fig1(b) the conventional tooth belt of Fig 1(a) is utilised in a different way: the two tooth belt sprockets rotate at opposite direction with the same 1:1 transmission ratio. The distance of the two tooth belt sprockets is smaller. The tooth belt forms a big "X" between the two sprockets, with the teeth, at the "center of the "X", facing each other. Fig 1(f) shows the belt of Fig 1(b) after the removal of the sprockets. In order to avoid the touching / wear / friction of the teeth, the two parts of the belt at the center of the "X" must be kept at a safety distance by a spacer, of by a roller or by a proper tensioner.

In Fig 1(c) an unconventional, as will be explained in the following, tooth belt interconnects the two sprockets; the sprockets rotate at opposite direction, with the same transmission ratio 1:1. Fig 1(g) shows the tooth belt of Fig 1(c) after the removal of the sprockets. In comparison to Fig 1(b), now at the middle of the "X" the backsides of the tooth belt face each other, leaving (and protecting this way) the teeth at the other "external" sides. The "basic" band or strip (i.e. the basis wherein the teeth of the tooth belt are secured / fixed) is substantially thinner as compared to the height of the teeth; even if the backsides of the tooth belt touch each other at the middle of the "X", the system works. If desired, the backside of the tooth belt can be covered with antifriction material. If desired, a spacer (for instance from Teflon) or a small roller can keep, at the center of the "X", the backsides of the tooth belt from touching each other. For the tensioning and fine-tuning of the tooth belt and sprockets, the known art is applicable.

The tooth belt of Fig 1(c) is unconventional.

Fig 2 shows the steps for "making" (actually for explaining the structure of) a belt like that of Fig 1(c) and 1(g), staring from a conventional tooth belt.

At Fig 2(a) it is shown a conventional tooth belt.

At Fig 2(b) the tooth belt of Fig 2(a) is properly cut. The "arrow" at the one end of the band shows the direction and the angle this end is to be twisted.

At Fig 2(c) the tooth belt of Fig 2(b) is twisted: keeping the one end immovable, the other end is twisted for two complete turns (720 degrees).

At Fig 2(d) the two ends of the band shown at Fig 2(c) are connected / secured to each other forming an unconventional / twisted tooth belt like that used in the Fig 1(c) and 1(g). The cut is not necessarily perpendicular to the band. Unlike the Mobius belt (or strip), here the belt has a backside rid of teeth and a front side wherein the teeth are mounted.

Fig 3 shows bigger the unconventional tooth belt of Fig 2(d). Applications: anywhere two shafts must rotate in synchronization at opposite direction.

For a tooth belt manufacturer, the cost for making either a conventional or this unconventional toothed belt is the same.

Claims

CLAIMS1. A twisted tooth belt engaging a pair of rotating shafts, the twisted tooth belt is comprising a closed loop strip and teeth at the one side of the closed loop strip, the closed loop strip is twisted at 720 degrees.
2. A twisted tooth belt engaging a pair of rotating shafts, as in claim 1, wherein the shafts of the pair of rotating shafts rotate at opposite direction.
3. A twisted tooth belt engaging a pair of rotating shafts, as in claim 1, wherein a toothed belt pulley is secured on each of the shafts of the pair of rotating shafts, with the twisted tooth belt arranged at an "X" between the tooth belt pulleys.
4. A twisted tooth belt engaging a pair of rotating shafts, as in claim 1, wherein: the closed loop strip has a backside rid of teeth, a toothed belt pulley is secured on each of the shafts of the pair of rotating shafts, the twisted tooth belt is arranged at an "X" between the tooth belt pulleys, at the center of the "X" the backsides of the closed loop strip face each other.
5. A twisted tooth belt engaging a pair of rotating shafts, as in claim 1, wherein: the closed loop strip has a backside rid of teeth, a toothed belt pulley is secured on each of the shafts of the pair of rotating shafts, the twisted tooth belt is arranged at an "X" between the tooth belt pulleys, at the center of the "X" the backsides of the closed loop strip face each other, a spacer at the center of the "X" keeps the backsides of the closed loop strip away from each other.
6. A twisted tooth belt engaging a pair of rotating shafts, as in claim 1, wherein: the closed loop strip has a backside rid of teeth, a toothed belt pulley is secured on each of the shafts of the pair of rotating shafts, the twisted tooth belt is arranged at an "X" between the tooth belt pulleys, at the center of the "X" the backsides of the closed loop strip face each other, a tensioner at the center of the "X" keeps the backsides of the closed loop strip away from each other.
7. A twisted tooth belt engaging a pair of rotating shafts, the twisted tooth belt is comprising a closed loop strip and teeth at the one side of the closed loop strip, the closed loop strip is such that starting from a point on its surface and moving along the strip until reaching the starting point, it performs two complete turns, whilst in the Mobius strip it performs half a turn.
8. A twisted tooth belt engaging a pair of rotating shafts, the twisted tooth belt is comprising a closed loop strip and teeth at the one side of the closed loop strip, the twisted tooth belt can be regarded as being derived from a conventional tooth belt after cutting it to make a band, twisting the one end of the band for 720 degrees relative to the other end of the band, and reconnecting the two ends.