GB1579889A

GB1579889A - Electromagnetic impact vibrator

Info

Publication number: GB1579889A
Application number: GB2231377A
Authority: GB
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1976-05-28
Filing date: 1977-05-26
Publication date: 1980-11-26
Also published as: FR2352595A1; DE2623855B2; ATA375977A; AT350141B; DE2623855A1; FR2352595B3; DE2623855C3

Description

(54) AN ELECTROMAGNETIC IMPACT VIBRATOR (71) We, LICENTIA PATENT VERWALT UNGS G.M.B.H., of 1 Theodor-Stern-Kai, 6 Frankfurt/Main 70, Federal Republic of Germany, a German body corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an electromagnetic impact vibrator. Such vibrator may comprise a base member with a shock surface thereon, a support structure on the base member to which an electromagnet is attached and on which an armature and the hammer fixed thereto are carried.

This type of impact vibrator is required in order to prevent bulk material in silo outlets and filling plant from caking against the walls and forming a bridge. These impact vibrators have an electromagnet system which is energized by an alternating current or pulsating direct current, in which a hammer is fixed to one part of the magnet system and a shock surface is attached to the other part, the hammer hitting the said shock surface during oscillation of the system, so that the device emits hard, periodic shocks in rhythm with the frequency of the tensioning force of the magnet to the fixing support. The spring tension between the two masses acts as an energy store for the structure oscillating close to its natural resonance and moreover generally seeks to guide the oscillatory motion in linear manner.

These springs may be steel yet many embodiments are known with rubber springs.

With a round, tubular cross-section of the inner and outer part oscillating contra to each other, the rubber springs have the form of a ring or cylinder firmly introduced between two components or the form of annular portions. With rectangular formation, the rubber elements have a rectangular, parallelepipedic form.

In each case it was necessary either to have specially designed and manufactured rubber elements or large and expensive classification work was necessary in order to select from commercial rubber elements those elements having the E modulus required for the particular purpose. Here to considerable difficulties of balancing and adjustment arise.

The invention seeks to create a simply constructed impact vibrator which is also simple in assembly in which commercially used rubber elements may be used and in which selection and adjustment in the impact vibrator does not create any significant difficulty.

In known arrangements setting of the air gap had to be effected in consideration of the spring characteristics during assembly, subsequent changes which were often necessary particularly because of the known ageing characteristics of the rubber elements, necessitated extensive dismantling of the device.

The present invention also seeks to create the possibility of undertaking air gap setting with respect to the spring features ?? the finished device and if necessary even in the assembled state on site and even during operation.

According to the invention, there is provided an electromagnetic impact vibrator comprising a base member with a shock surface thereon, a support structure on the base member to which an electromagnet is attached and on which an armature and hammer are carried movably by elastomeric elements, cup springs or cup spring packages being provided between the elastomeric elements and the support structure, having a spring constant higher than that of the elastomeric elements by a multiple thereof and having an externally adjustable prestress.

In order to be able to set both air gaps of the impact vibrator: the shock air gap and the magnet air gap to optimum spacings, in accordance with a further feature of the invention, it may be advisable if the electromagnet is fixed to the support structure by interconnection of leaf springs having an externally adjustable prestress, which controls the position of the electromagnet in the structure. The high spring constant of the leaf springs can ensure that fastening, with regard to the operating oscillation, is sufficiently rigid and in fact only the rubber elements are involved in the oscillation.

The invention will now be described in greater detail, by way of example with reference to the drawings, in which: - Figure 1 shows a side view partially in section, Figure 2 shows a plan view partially cut away.

A shock-resistant anvil 2 and the boxshaped or cylindrical casing 3 of the impact vibrator, said casing being sealed off with a lid and surrounding the anvil 2, are fixed centrally to the base 1. The impact vibrator comprises a periodically energized electromagnet member 4 fixed to the cover together with a carrier 5 of an armature 8 and a hammer 7, which carrier 5 is fixed between the magnet member 4 and the anvil 2 so as to oscillate. 7'he oscillation of this member is ensured by the matched fixing of two or more symmetrically distributed rubber elements 6 having particularly selected spring characteristics. On both sides of this member, i.e. between the hammer 7 and the anvil 2 as well as between the magnet member 4 and the armature 8 are located, in the state of rest, precisely dimensioned air gaps 9 or 10.With a pulselike energization of the magnet member 4, the armature 8 is drawn in against the spring force of the rubber elements 6 and when the current pulse dies away the armature 8 performs a throwing motion with great force as a result of the stored spring forces of the rubber elements 6, so that the hammer 7 hits violently against the anvil 2.

As a result of periodic current pulse energization of the magnet member 4, regular knocking takes place. In order to prevent damage to the system, the armature 8 of the magnet system is prevented from hitting against the magnet member 4. In addition it is necessary, in order to achieve optimum conditions of shock energy and consumption of exciter energy, to bring the characteristic curves of resilience of the rubber elements 6 and the width of the air gaps 9 and 10 into quite definite relationships with regard to each other.

The fact that the rubber elements 6 are fixed to the screw bolts 12 with interconnection of cup springs or cup spring packages 11 by the screw bolts 12 passing through the casing wall makes recalibration possible at any time. The spring constant of the cup springs 11 is greater than that of the rubber elements 6, by a multiple, so that the influence on the oscillation characteristics of the oscillating system is negligible.

By means greater or lesser tightening of the bolts 12, the armature 8 and the hammer carrier 5 are raised or lowered and change the air gaps 9 and 10 under greater or lesser compression of the cup spring package 11.

In order to be able to match the magnet member 4 to the variations with an equally small amount of effort it may be advisable for this magnet member 4 to be fixed to the base of the casing 3 by bolts 14, cup spring packets 11 being interposed between the magnet member 4 and the base of casing 3. Here too, the magnet member 4 may be raised by tightening the screw fastening 14 and thus the air gaps 9 and 10 may be enlarged.

In the construction shown in the example, having rubber elements 6 under actual pressure and their screw fastening 12 aligned in the direction of oscillation, flattened portions or recesses 13 are preferably provided in the casing 3 with surfaces lying parallel to the base-plate 1, the screw fastenings 12 being arranged on these surfaces without any difficulty and their displacement, which takes place later from outside, is also without difficulty, its purpose being readjustment of the air gaps.

WHAT WE CLAIM IS: - 1. An electromagnetic impact vibrator comprising a base member with a shock surface thereon, a support structure on the base member to which an electromagnet is attached and on which an armature and hammer are carried movably by elastomeric elements, cup springs or cup spring packages being provided between the elastomeric elements and the support structure, having a spring constant higher than that of the elastomeric elements by a multiple thereof and having an externally adjustable prestress.

2. An impact vibrator according to Claim 1, wherein the electromagnet is fixed to the support structure with the interposition of cup springs having an externally adjustable prestress.

3. An impact vibrator according to Claim 1 or 2, wherein the support structure is a casing of approximately bellshaped form and the adjustable prestressing is achieved by screw tensioners mounted on flattened portions or recesses running parallel to the base member.

4. An electromagnetic impact vibrator substantially as described herein with reference to the drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. having an externally adjustable prestress, which controls the position of the electromagnet in the structure. The high spring constant of the leaf springs can ensure that fastening, with regard to the operating oscillation, is sufficiently rigid and in fact only the rubber elements are involved in the oscillation. The invention will now be described in greater detail, by way of example with reference to the drawings, in which: - Figure 1 shows a side view partially in section, Figure 2 shows a plan view partially cut away. A shock-resistant anvil 2 and the boxshaped or cylindrical casing 3 of the impact vibrator, said casing being sealed off with a lid and surrounding the anvil 2, are fixed centrally to the base 1. The impact vibrator comprises a periodically energized electromagnet member 4 fixed to the cover together with a carrier 5 of an armature 8 and a hammer 7, which carrier 5 is fixed between the magnet member 4 and the anvil 2 so as to oscillate. 7'he oscillation of this member is ensured by the matched fixing of two or more symmetrically distributed rubber elements 6 having particularly selected spring characteristics. On both sides of this member, i.e. between the hammer 7 and the anvil 2 as well as between the magnet member 4 and the armature 8 are located, in the state of rest, precisely dimensioned air gaps 9 or 10.With a pulselike energization of the magnet member 4, the armature 8 is drawn in against the spring force of the rubber elements 6 and when the current pulse dies away the armature 8 performs a throwing motion with great force as a result of the stored spring forces of the rubber elements 6, so that the hammer 7 hits violently against the anvil 2. As a result of periodic current pulse energization of the magnet member 4, regular knocking takes place. In order to prevent damage to the system, the armature 8 of the magnet system is prevented from hitting against the magnet member 4. In addition it is necessary, in order to achieve optimum conditions of shock energy and consumption of exciter energy, to bring the characteristic curves of resilience of the rubber elements 6 and the width of the air gaps 9 and 10 into quite definite relationships with regard to each other. The fact that the rubber elements 6 are fixed to the screw bolts 12 with interconnection of cup springs or cup spring packages 11 by the screw bolts 12 passing through the casing wall makes recalibration possible at any time. The spring constant of the cup springs 11 is greater than that of the rubber elements 6, by a multiple, so that the influence on the oscillation characteristics of the oscillating system is negligible. By means greater or lesser tightening of the bolts 12, the armature 8 and the hammer carrier 5 are raised or lowered and change the air gaps 9 and 10 under greater or lesser compression of the cup spring package 11. In order to be able to match the magnet member 4 to the variations with an equally small amount of effort it may be advisable for this magnet member 4 to be fixed to the base of the casing 3 by bolts 14, cup spring packets 11 being interposed between the magnet member 4 and the base of casing 3. Here too, the magnet member 4 may be raised by tightening the screw fastening 14 and thus the air gaps 9 and 10 may be enlarged. In the construction shown in the example, having rubber elements 6 under actual pressure and their screw fastening 12 aligned in the direction of oscillation, flattened portions or recesses 13 are preferably provided in the casing 3 with surfaces lying parallel to the base-plate 1, the screw fastenings 12 being arranged on these surfaces without any difficulty and their displacement, which takes place later from outside, is also without difficulty, its purpose being readjustment of the air gaps. WHAT WE CLAIM IS: -

1. An electromagnetic impact vibrator comprising a base member with a shock surface thereon, a support structure on the base member to which an electromagnet is attached and on which an armature and hammer are carried movably by elastomeric elements, cup springs or cup spring packages being provided between the elastomeric elements and the support structure, having a spring constant higher than that of the elastomeric elements by a multiple thereof and having an externally adjustable prestress.