NZ527457A - Electric motor with elastomeric bushes and pads located between components, typically for vibrating motors - Google Patents

Abstract

Two body portions 1,2 house the motor components. Elastomeric bushes and pads are located on the outer and inner portions of the armature bearings, and between field windings and the interior of portions 1,2.

Description

527457 Patents Form No 5 Patents Act 1953 Number 527457 Date 8 August 2003 COMPLETE SPECIFICATION We, Arapal Developments Ltd, a New Zealand company, of 4 Riccarton Road, Christchurch 8004, New Zealand, hereby declare the invention for which we pray that a 30 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; 1 intellectual property office of n.z. 1 8 AUG 2004 RECEIVED • 25 Electric motor TITLE Electric motor BACKGROUND An electric motor is often designed and constructed for a specific purpose and in particular, but not necessarily, the electric motor of the present invention has been designed to be used with equipment such as electrical vibratory massage apparatus. Such a motor generally either has an out of balance weight attached directly to the motor shaft or the shaft is connected directly or indirectly to an out of balance weight. In 10 known modifications, the out-of balance weight can be attached to each end of the motor shaft and can also take the form of a cooling fan for the motor.

The intentional vibrations generated by the out of balance weights when the motor is running can be quite severe and unless the motor is specially constructed, the 15 vibrations can, over a period of time destroy the motor.

Utilisation of an electric motor to generate vibrations for massage equipment is described for instance in US patent specification 4,535,760 (Ikeda) and US patent specification 4,730,605 (Noble).

Another requirement of an electric motor to be used in conjunction with vibratory massage apparatus is that the speed of rotation of the shaft of the motor must be able to be varied and once varied be able to be kept constant at the desired speed. Another desirable feature of an electric motor when used with electrical massage 25 equipment is that it be as physically as small as possible and it is even more desirable that the motor be able to run satisfactorily on low voltages in comparison with those voltages normally available in mains fed domestic situations. A further desirable feature is that the motor can run on direct current so the speed of rotation of the motor can be simply controlled electronically. 2 In addition to the above criteria, it is also highly desirable that an electric motor be of a construction that it is composed of a minimum of component parts and which are so constructed that the assembly and disassembly of the motor is facilitated.

OBJECT OF THE INVENTION It is accordingly an object of this invention to provide an improved construction of electric motor that will meet as far as possible the above desiderata and which will provide an advance both in the form of construction of an electric motor and will tend to maximize the service life of the motor.

It is also an object of the invention to provide a construction of an electric motor that will have the desired resonance which will assist in counteracting the destructive forces imparted to the motor when an out of balance weight at attached to the armature shaft.

SUMMARY OF THE INVENTION Accordingly in one preferred form of the invention there is provided an electric motor comprising two body portions adapted to be assembled to form a substantially cylindrical 20 body to house the component parts of the motor, an annular wall located at either end of each body portion and adapted when the cylindrical body is assembled to form a bearing housing to receive an armature shaft bearing to support an armature shaft for the motor, said bearing having an outer shell 25 and an inner bore, an elastomeric bushing located between the inner bore of each armature shaft bearing and the armature shaft an elastomeric pad located between the outer shell of the armature shaft bearing and the bearing housing, 3 a first field elastomeric pad sandwiched between a first outer face of a field winding assembly and the interior of the cylindrical body and a second field elastomeric pad sandwiched between a second outer face of the field winding assembly and the 5 interior of the cylindrical body, the first and second field elastomeric pads locating the field winding assembly within the cylindrical body, wherein the location and composition of the elastomeric bushing, the field elastomeric pad and the armature bearing elastomeric pad provide a combined synergistic dampening effect to forces generated when the motor is running with an out of balance weight attached to the armature shaft.

Preferably a groove is formed in the bearing housing into which the outer shell of the armature bearing may engage.

Preferably the first outer face of the field winding assembly is oriented parallel to the second outer face of the field winding assembly with the first and second outer faces being located on opposite sides of the field winding assembly.

Preferably the elastomeric bushing is electrically conductive and has a predetermined degree of hardness and resiliency.

Preferably the electrically conductive elastomeric bushing is initially separate from the bearing.

Preferably a sleeve is located on the exterior of the cylindrical body adjacent either end of the body.

Preferably an annular land is formed on the exterior of the cylindrical body adjacent either end of the body and the sleeve is located in each land. 4 Preferably the sleeve is composed of a resilient material.

Preferably the motor is configured as a direct current shunt wound motor.

Preferably the electrical components are configured to enable the motor to operate on a direct current electrical supply.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described with the aid of the accompanying drawings wherein: Figure 1 is a three quarter view of an assembled motor constructed in accordance with the present invention.

Figure 2 is a side view of the assembled motor in the direction of the arrow A of Figure 1.

Figure 3 is a side view of the assembled motor in the direction of the arrow B of Figure 1.

Figure 4 is an exploded view of the component parts of the motor.

Figure 5 is a partly diagrammatic representation of another form of body shell for the motor.

BEST MODE OF PERFORMING THE INVENTION As illustrated in the drawings, two substantially identical semi circular body portions 1 and 2 are assembled to form a substantially cylindrical housing for the motor. The body portions 1 and 3 are preferably but not necessarily formed of an injection 30 moulded plastic material. As can be seen from the Figures 1 to 4 of the drawings the body portions include annular walls 3 at either end which in a highly preferred form are substantially identical. Adjacent one annular wall 3, the body portion also includes brush holders 4 (see Figure 4) which are channel shaped to receive the brushes 5 which includes the usual compression springs 6 and electrical connections 7.

The brush holders 4 are so formed that the brushes will have a sliding movement within the holders to enable each brush can bear against a commutator 9 of the armature 10. As illustrated, the armature includes an armature shaft 11 with each end engaged within an armature bearing 13. In a highly preferred form each armature bearing consists of a single race of ball bearings or rollers, but it is to be understood that in 10 certain circumstances it may be desirable to utilise a bearing having a double or even a triple race of ball bearings or rollers. In addition, in a highly preferred form, the armature bearing 13 is of the sealed variety to prevent the ingress of unwanted matter. which will act as a housing for each armature bearing 13. The armature shaft 11 is supported in each armature bearing 13 by means of an elastomeric bushing 14 which is preferably electrically conductive to ensure any build up of static electricity can be drained away. In addition the composition of the elastomeric substance is arranged to provide a desired degree of hardness and resiliency to supplement the resonance of the 20 component parts of the motor as will be further described herein. The elastomeric bushing 14 can in one form be an initially separate component or it can be formed as an integral part of the armature bearing 13. 18 can be located within the body portion and be retained in its correct location. The field winding assembly 18 is retained within the body by means of field pads 19 which are also formed of an elastomeric material which is sufficiently robust and resilient to ensure the field winding is correctly located within the assembled body portions, and which will also contribute to the desired combined resonant frequency of the motor.

The field pads 19 are constructed so that in use they will be sandwiched between the face 25 of the field winding assembly 18 and the interior of the body portions 2 to assist When the two body portions are assembled an axial bore 13 A will be formed The interior of each body portion 2 is formed so that the field winding assembly 6 in firmly locating the component parts within the body of the motor. The field winding assembly 18 includes appropriate electrical terminals 20 to enable electrical current to be fed to the windings as is known in the art.

As illustrated more particularly in Figure 4 the bearing housing 13A includes a bearing groove 15 to receive the armature bearing 13. An elastomeric resonant pad 16 is located between the outer race of the armature bearing 13 and the groove 15 to further assist in the generation of the desired resonance of the motor as will be hereinafter further explained. When the two body portions 1 and 2 are assembled, the bearing 10 grooves 15 which will in conjunction with the resonant pad will firmly retain the bearings 13 in position in the bearing housing.

When the motor is to be utilised in conjunction with vibratory massage equipment, an out of balance weight (not shown in the drawings) will generally be 15 secured to one or both ends of the shaft 11 so that as the shaft rotates a vibratory effect will be produced by the motor which will be transmitted to the massage equipment. It is highly desirable that the waveform of the vibrations generated by the motor be able to be modulated irrespective of the rotational speed of the motor and the type of out of balance weights used to produce the vibratory waveform. To enable this the degree of 20 hardness, size and resiliency of the elastomeric bushing 14, the field winding pads 19 and the bearing pads 16 are chosen to enable the desired resonance and dampening to be obtained. The actual composition of the three components, that is the elastomeric bushing 14, the bearing pads 16 and the field winding pads 19 can be varied as it known in the art to ensure the combination of the three components will provide the desired 25 dampening and resonant effect.

Appropriate ventilation holes 22 are formed in the ends of the body portions and in the form illustrated particularly in Figure 4, the body portions include lands 23 which are provided with mounting holes 24 so that when the two body portions 1 and 2 have 30 been assembled into the form illustrated in Figure 1, appropriate fixing means such as bolts 26 can be passed through the mounting holes secured with nuts or the like to 7 maintain the two body portions together. Instead of the bolts 26, other fixing means such as screws or the like as known in the art can be utilised.

The exterior of the body portions 1 and 2 is preferably formed with an annular 5 land 27 on which a sleeve 28 (see Figure 4) is located, this sleeve in a highly preferred form is composed of cork or other suitable resilient material to facilitate the mounting of the motor within a suitable housing (not shown in the drawings).

In a modification to the invention as illustrated in Figure 5, the body portions 1 10 and 2 are extended axially and appropriate means, (not shown in the drawings) are utilised to secure the two body portions together after the component parts have been assembled to form a complete motor such as that illustrated diagrammatically in the Figure. The advantage of this form of the invention is that the component parts of the motor and in particular the elastomeric bushing 14, the bearing pads 16 and the field 15 winding pads 19 can be so constructed to enable the motor as a whole to have a different resonance which can be of particular application when the motor is used with larger massage equipment such as beds, chairs and the like.

The construction of the motor as illustrated has been particularly designed not 20 only so it is robust but also so it can be very simply assembled and if necessary dismantled. The assembly of the motor is effected by assembling the bearings 13 and the elastomeric bushing 14 on the armature shaft 11 and then passing the armature through the field winding. The elastomeric resonant pads 19 are positioned inside the body shell to register with the faces 25 of the field winding 18, the electrical wiring is 25 attached to the field winding 18 and the connections 7 of the brushes 5 in a known manner and the component parts are assembled into the respective body portions 1 and 2 which are then secured together by the fixing means, such as the bolts 26.

The motor in its highly preferred form has a series wound field and armature 30 which is configured as a direct current shunt. 8 The essential purpose of the electric motor is to enable an out of balance weight, which may also be in the form of a fan (not shown in the drawings) which is located on and fixed to one end of the shaft. In a modification an out of balance weight is located on the shaft 11 together with a fan. In yet another modification the out of balance weight is located on each end of the armature shaft. In this configuration it is possible to tune the out of balance forces to provide variable degrees and effects of vibration. In addition, the composition and the form of the elastomeric components is arranged to provide the desired degree of dampening of the vibrations generated by the rotation of the out of balance weight or weights attached to the shaft 11 of the motor.

The use of the elastomeric electrically conductive bushings provides as before described, an electrical path for the transmission of any static electricity that may be built up when the motor it operating. In addition the bushings have the considerable advantage of allowing an easy press fit of the bearing 13 on the shaft 11 and also 15 facilitates the required tolerances that may arise during manufacture of the component parts. In addition the elastomeric bushings achieve the desired vibratory relationship between the shaft which carries the out of balance forces and the transmission of the out of balance forces through the bearings 13 to the outer casing of the motor.

Having described preferred methods of putting the invention into effect, it will be apparent to those skilled in the art to which this invention relates, that modifications and amendments to various features and items can be effected and yet still come within the general concept of the invention. It is to be understood that all such modifications and amendments are intended to be included within the scope of the present invention. 9

Claims (8)

1. An electric motor comprising; two body portions each being substantially semi circular in cross section and 5 adapted to be assembled to form a substantially cylindrical body to house the component parts of the motor, an annular wall located at each end of each body portion formed when the cylindrical body is assembled to provide a bearing housing to receive an armature 10 bearing assembly to support an armature shaft for the motor, said bearing armature bearing assembly consisting of; an armature bearing having an outer shell and an inner bore, 15 an electrically conductive elastomeric bushing located between the inner bore of the bearing and the armature shaft and an elastomeric pad located between the outer shell of the bearing and the bearing housing, 20 the electric motor also including; a first field pad sandwiched between a first outer face of a field winding assembly of the motor and the interior of the cylindrical body and a second field pad sandwiched between a second outer face of the field winding assembly and the interior 25 of the cylindrical body to thereby locate the field winding assembly within the cylindrical body; the first and second field pads each being formed of an elastomeric material

2. The electric motor as claimed in claim 1, wherein the first outer face of the field 30 winding assembly is oriented parallel to the second outer face of the field winding Intellectual Property 10 office of NZ 0 5 JAN 2006 RECEIVED assembly with the first and second outer faces being located on opposite sides of the field winding assembly.

3. The electric motor as claimed in claim 1, wherein the electrically conductive 5 elastomeric bushing is initially separate from the bearing.

4. The electric motor as claimed in claim 1, wherein a sleeve is located on the exterior of the cylindrical body adjacent either end of the body. 10

5. The electric motor as claimed in claim 4, wherein an annular land is formed on the exterior of the cylindrical body adjacent either end of the body and wherein a sleeve is located on each land.

6. The electric motor as claimed in claim 5, wherein the sleeve is composed of a 15 resilient material.

7. The electric motor as claimed in claim 1, wherein the motor is configured as a direct current shunt wound motor. 20

8. The electric motor as claimed in claim 1, wherein the electrical components are configured to enable the motor to operate on a direct current electrical supply. Intellectual P<J>E?rty Office of NZ 11 0 5 JAN 2006 received