GB2064063A - Improved means for regulating vibratory mechanisms - Google Patents

Abstract

A four shaft eccentric mass vibration exciter 3 for vibration of the trough 1 of a vibratory feeder is driven through a gear-box by a motor 8 connected to one gear-box shaft. This gear-box shaft is provided with a helical gear 13 and is connected to drive one pair of shafts 4 of the exciter. The other pair of shafts 5 of the exciter is driven by a second gear- box shaft which is also provided with a helical gear 16. A third gear-box shaft 15 is provided with a pair of helical idler gears 14, 14A one of which meshes with the helical gear 13 of the first gear-box shaft, the other meshes with the helical gear 16 of the second gear-box shaft. The arrangement is such that upon axial displacement of the gears 14, 14A along the shaft 15 rotation of the helical idler gears 14, 14A relative to the third shaft changes the phase of rotation between the first and second shaft pairs of the exciter. <IMAGE>

Description

SPECIFICATION Improved means for regulating vibratory mechanisms This invention relates to regulation of vibratory mechanisms and in particular to apparatus adapted to vibrate feeder devices.

There are several conventional techniques for achieving vibration of feeder devices. The most common such technique resides in the use of rotating eccentric counterweights so that a force is created which rotates at the speed of revolution of the shaft carrying eccentric weights. In many applications a vibrating force moving along one direction of action only is required and for this type of machine it is common to use two shafts carrying eccentric weights and to gear them together so that the rotating forces add in a first direction and cancel in another direction at right angles to the first direction. Where it is desired to vary the vibrating force for the purposes of control such as to control the rate at which bulk particulate materials move along a vibrating surface, the most common method in the past has been to vary the speed at which the eccentric weights revolve.Variable speed drives, such as D.C motors, or other means, are common and easily available. They are, however, complicated and in the larger sizes use a great number of electric and electronic components so that they suffer from poor reliability.

Another method of varying the force developed by vibratory exciters is to use an exciter with four shafts. In this case the shafts operate in pairs, where one pair of shafts provide a straight line vibrating force and the other pair of shafts is arranged so that they provide a vibrating force in the same direction as the first pair but the forces from the two pairs can be added or subtracted from each other by varying the phase between the two pairs of rotating shafts. In the past the mechanical methods to obtain this change of phase have been sufficiently complicated that they do not compare well with the variable speed methods of regulating the force from a pair of rotating shafts.

A recent example of four shaft vibratory exciter is to be found in the disclosure of U.K.

Specification 2,017,863. That application depicts and describes such an exciter wherein the kinematic connection between a shaft of one pair of rotating shafts and the shaft of the other pair of rotating shafts, in order to transmit rotation from one said shaft to the other, comprises a pair of gear wheels meshing together and each kinematically connected to a respective shaft so as to rotate therewith, the gear wheels being movable to one another by rolling on their engaging surfaces. This arrangement is complex, expensive to manufacture and probably commercially undesirable.With particular reference to the drawings of that application Figure 1 depicts arcuate rack 31 which must rotate through approximately 450 in order to transmit rotation from shaft 1 8 to shaft 1 9. The arrangement also requires use of a helical sliding spline in shaft 1 8. Such a spline is difficult to manufacture and to maintain.

It is an object of this invention to ameliorate the disadvantages of known vibratory feeder exciters.

This invention in one broad form provides vibratory apparatus of the four shaft exciter type comprising a first pair of shafts each provided with an eccentric weight, the shafts of said first pair being drivable to provide a vibrating force, a second pair of shafts each provided with an eccentric weight, the shafts of said second pair being drivable to provide a vibrating force in the same direction as that of the first pair of shafts, the arrangement being such that the forces produced from the driven shaft pairs may be added to or subtracted from each other by varying the phase of rotation between the shaft pairs, and means for varying the phase of rotation between the first and second shaft pairs, comprising a gearbox having three parallel shafts, a first gear-box shaft being drivably connected to one shaft of said first pair of shafts and being driven by a motor, a second gear-box shaft being drivably connected to one shaft of said second pair of shafts, said first and second shafts each being provided with an helical gear the helixes on said gears being oppositely directed, and a third gear-box shaft provided with a pair of helical idler gears the first idler gear meshing with the helical gear on the first gear-box shaft and the second idler gear meshing with the helical gear on the second gear-box shaft, said first and second idler gears being restrained to rotate in the same direction and at the same speed, and wherein said first and second idler gears are movable axially together along the axis of said third gear-box shaft.

By way of example only one embodiment of a four shaft vibratory exciter according to this invention will now be described with reference to the accompanying drawings wherein: Figure 1 depicts a four shaft exciter and phasing gear-box in accordance with this invention coupled to a feeder to be vibrated; Figure 2 depicts the minimum position of the eccentric weights of the exciter; Figure 3 depicts the maximum position of the eccentric weights of the exciter; Figure 4 depicts the internal arrangement of the phasing gear-box of this apparatus.

In the drawings four shaft vibratory exciter 3 is coupled to trough 1 which is to be vibrated.

Trough 1 is provided with suspension springs 2 to isolate trough 1 during vibration from the surrounding structure. Exciter 3 incorporates a first pair 4 of rotating shafts and a second pair 5 of rotating shafts. Cardan shaft 6 connects one shaft of each pair of rotating shafts to a respective shaft of phasing gear-box 7. Motor 8 is adapted to drive one shaft of phasing gear-box 7.

Figure 2 illustrates two pairs of rotating eccentric weights, first pair 9 and 10 and second pair 11 and 12. The shafts carrying eccentric weights 9 and 10 are geared together so that those weights rotate in opposite directions to produce a linear vibrating force. In Figure 2 weights 9 and 10 are producing such a force towards the left of the drawing. The other pair of weights 11 and 12 are also geared together and are depicted as producing a linear vibrating force towards the right of the drawing. Clearly, if all the eccentric weights 9 and 10 and 11 and 12 are identical in mass and eccentricity the forces to the right and left will cancel giving no net vibrating force.

In Figure 3 two pairs of rotating eccentric weights are depicted, the pairs again being 9 and 10 on the one hand and 11 and 12 on the other.

By comparison with Figure 2 both pairs of eccentric weights in Figure 3 are producing individual linear vibrating forces towards the left and if the forces from both pairs of weights are added a maximum force in that direction will be achieved.

Phasing gear-box 7 (Figure 1) incorporates two helical gears 13 and 16. These gears are mounted integrally with their respective shafts. The helix on gear 1 3 is opposite to that on gear 16. Disposed centrally between gears 13 and 1 6 is a pair of idler gears 14 and 1 4A. These gears 14 and 1 4A are mounted on shaft 1 5 and are free to rotate on shaft 1 5. Idler gears 14 and 1 4A are restrained to rotate in the same direction and at the same speed and are movable axially together along the axis of third gear-box shaft 13. Idler gear 14 meshes with gear 1 6 and has the appropriate helix for that purpose as depicted.

Idler gear 1 4A meshes with helical gear 13 and also has the appropriate helix for that purpose.

Idler gears 14 and 1 4A can be driven to any position along shaft 1 5 by any suitable means such as a lead screw (not shown).

A man skilled in the art will appreciate that as idler gears 14 and 1 4A move along shaft 15 the phase between helical gears 13 and 1 6 will change producing the desired vibrating effect as a result of a comparatively simple mechanical arrangement.

Claims (6)

1. Vibratory apparatus of the four shaft exciter type comprising: a first pair of shafts each provided with an eccentric weight, the shafts of said first pair being drivable to provide a vibrating force; a second pair of shafts each provided with an eccentric weight, the shafts of said second pair being drivable to provide a vibrating force in the same direction as that of the first pair of shafts, the arrangement being such that the forces produced from the driven shaft pairs may be added to or subtracted from each other by varying the phase of rotation between the shaft pairs; and means for varying the phase of rotation between the first and second shaft pairs, comprising a gear box having three parallel shafts, a first gear-box shaft being drivably connected to one shaft of said first pair of shafts and being driven by a motor, a second gear-box shaft being drivably connected to one shaft of said second pair of shafts, said first and second shafts each being provided with an helical gear the helixes on said gears being oppositely directed, and a third gear-box shaft provided with a pair of helical idler gears the first idler gear meshing with the helical gear on the first gear-box shaft and the second idler gear meshing with the helical gear on the second gear-box shaft, said first and second idler gears being restrained to rotate in the same direction and at the same speed, and wherein said first and second idler gears are movable axially together along the axis of said third gear-box shaft.

2. Vibratory apparatus as defined in claim 1, wherein the vibrating forces provided by the shafts of both the first pair of shafts and of the second pair of shafts are in a collinear straight line direction.

3. Vibratory apparatus as defined in claim 1 or claim 2, wherein said first, second and third gearbox shafts have co-planar axes, the third gear-box shaft being disposed between the equidistant from said first and second gear-box shafts.

4. Vibratory apparatus as defined in claim 3, wherein the first and second idler gears are of equal diameter.

5. Vibratory apparatus as defined in any one of the preceding claims, wherein said first gear-box shaft is directly connected to said one shaft of said first pair of shafts by a cardan shaft.

6. Vibratory apparatus substantially as described herein with reference to and as illustrated by the accompanying drawings.