US2950359A

US2950359A - Loud speaker assembly

Info

Publication number: US2950359A
Application number: US613187A
Authority: US
Inventors: Charles A Perry
Original assignee: ROLA Co Inc
Current assignee: ROLA Co Inc; ROLA COMPANY Inc
Priority date: 1956-10-01
Filing date: 1956-10-01
Publication date: 1960-08-23
Anticipated expiration: 1977-08-23

Description

Aug. 23, 1960 c. A. PERRY LOUD SPEAKER ASSEMBLY Filed 001;. l, 1956 ZNVENTOR. CHARLES A. PERRY ,4 TT'ORNEYS ilnited States Patent LOUD SPEAKER ASSEMBLY Charles A. Perry, Cieveland, Ohio, assignor to The Rola Company, Inc, (Ileveland, Ohio, a corporation of Uhio Filed Oct. 1, 1956, Ser. No. 613,187

2 Claims. (Cl. 179-1155) This invention relates to an improved and simplified construction and method for assembling and mounting a permanent magnet field structure on the diaphragm housing of a loud-speaker.

Loud-speaker assemblies usually include a diaphragm supporting structure in the form of a housing and a magnetic field structure for energizing the diaphragm voice coil. In a permanent magnet type loud-speaker, the field structure may include a yoke, a magnet mounted thereon, a pole tip, a front plate and some arrangement for protecting the air gap from the accumulation of foreign particles. An inherent problem in the construction and assembly of permanent magnet type loud-speakers is the excessive labor and cost involved in the multiple handling of the component parts. There are also additional supplemental operations required to adjust the magnet and to insure that the diaphragm voice coil is properly centered in the air gap formed by the field structure.

It is a principal object of this invention to provide a simplified and improved construction and method for assembling and mounting a permanent magnet field structure on the diaphragm housing of a loud-speaker without the need for cement, soldering or threaded fasteners of any kind.

A further object of this invention relates to the 'provision of an improved construction and method of as.- sembling and mounting a permanent magnet field structure on the diaphragm housing of a loud-speaker which automatically and permanently centers the pole tip in the air gap during such assembly and mounting.

Briefly, the foregoing objectives are attained in accordance with this invention by providing a U-shaped yoke with projecting guides that are adapted to pass through properly located apertures in a front plate which are in turn aligned with similarly located apertures on a diaphragm supporting housing. The diaphragm housing and front plate include central bores for receiving the voice coil which are adapted to be axially aligned by virtue of the alignment of the foregoing apertures on the projecting guides. The front plate has projecting pins spaced circumferentially about the central bore on its rear face which are adapted to engage similarly located apertures on a mating flange of a magnet centering member. The centering member is made of non-magnetic resiliently flexible material and is cupshaped with a depressed central portion that is adapted to overlie the central bore in the front plate when mounted thereon. The front plate and centering member are first assembled as a sub-assembly by staking them together and at the same time piercing a bore through the depressed portion of the centering member which will be concentric with the bore in the front plate so that a core tip projecting through the centering member bore will be concentric with the front plate bore. This is accomplished by piloting the piercing operation through the bore in the front plate. A permanent magnet is supported within the yoke with its projected axis extending through the concentric bores and a pole tip is mounted on the projected extremity of the magnet and secured in centered position within the concentric bores by means of the non-magnetic centering member. The yoke, magnet, pole tip and the centering member and front plate sub-assembly are then assembled on the diaphragm housing with the yoke guides extending through the apertures in the front plate and diaphragm housing. Pressure is then applied to deform the projecting extremities of the guides and thereby fasten the component parts together. The depth of the depressed portion of the centering member is such that the pressure will collapse the depressed portion slightly and the resiliency of the centering member will hold the pole tip in centered relation within the front plate bore.

In the drawings:

Fig. 1 is a side elevation of a loud-speaker having the field structure partially cut away to illustrate the interior;

Fig. 2 is an exploded perspective view of the subassembly of a front plate and core tip dust cup at an intermediate stage of assembly;

Fig. 3 is an exploded perspective view of the field structure in relation to the diaphragm housing; and

Fig. 4 is an enlarged sectional view of the centering portion of the assembly.

Referring now more particularly to Figs. 1 and 3 of the drawings, there is shown a preferred form of the loud-speaker assembly of this invention having a permanent magnetic field structure which includes a yoke, indicated generally at It), which is formed from a metal blank bent in the form of an open U-frame having a back plate 11 and

sides

12 and 13. The field structure also includes a magnet 15, and a pole tip 16 and a sub-assembly which includes a front plate 18 and a centering member 19 which is fastened thereto by projecting nubbins 32.

The

sides

12 and 13 of the yoke 10 are provided with outwardly projecting

tangs

21 and 22 at their extremities so devised as to project through spaced apertures 23 and 24 respectively in the front plate 18 and subsequently through similarly located

apertures

26 and 27 in the rear of the diaphragm housing 20. The apertures in the front plate and diaphragm housing are located so that when they are aligned with each other along the

tangs

21 and 22, the housing 17 will be aligned axially with a central bore 28 in the front plate 18. The magnet 15 is supported on the back plate 11 of the yoke and in turn is extended axially by the pole tip 15 which extends through axially aligned bores 29, 28 and 17 in the centering member 19, the front plate 18 and diaphragm housing 20 in such manner as to define a concentric air gap surrounding the pole tip, which is adapted to receive in centered relation a voice coil 36 carried by the throat of the diaphragm.

Referring now more particularly to Fig. 2 of the drawings, the front plate 18 and centering member 19 are shown dis-assembled in the exploded view to expose the projecting nubbins 32 on the rear face of the front plate, which are spaced from each other circumferentially about the central bore 28. The centering member 19 is composed of a resiliently flexible and non-magnetic cup-shaped member having a planular flanged portion 33 with apertures 34 through the respective corners for receiving the nubbin-like projections 32 on the rear face of the front plate. The central portion 35 of the centering member is depressed to form a dust cup which is adapted when assembled to surround the pole tip 16. In the preferred form shown, the centering member is staked to the front plate 18 and the depressed dust cup portion 35 is pierced by a suitable die which is piloted through the bore 28 in the front plate 18 to make the bore 29 concentric with the bore 28. In assembly the bore 29, which is of substantially the same or slightly greater diameter than that of the pole tip 16, automatically guides the pole tip into centered relationship and is maintained fixed without fear of distortion from bumps that normally occur in the rough handling incident to the packing and a of a press. The magnet 15 is then located in a slight recess 36 which is provided on, the inner face of the back plate 11 to insure that the magnet will not slide'out of the yoke. The pole tip 16, which is provided with a flange 37 on one extremity, is inserted into the bore of the centering member 19, and the pole tip and sub-as sembly of the front plate 18 and centering member 19 are then placed as a unit upon the yoke with the fangs 21a nd 22 projecting through apertures 23 and 24 in the front: plate 18. This 'operatesto position the magnet,

and pole tip 16 in centered alignment and at the same time brings the flanged end '37 of the pole tip into abutting engagement against the adjacent end of the magnet. 3 r j Thereafter, the diaphragm housing 2.0 is placed over the front plate 18 with the

apertures

26 and 27 in registration with the apertures 23 and 24, at which time the

tangs

21 and 22 project through the apertures. While the assembly 'is so held on the stationary head of the press, the movable head of the press is brought down so as to swage the

tan'gs

21 and 22 against the front face of the diaphragm housing 20. The depth of the central depressed portion135 of the centering member 19 is such that the press initially collapses the portion 35 slightly against the flange 37 and causes the wall of the portion 35 to deform inwardly to insure a tightly centered assembly of the component parts. The position of the portion 35 before and after the application of pressure by the press is illustrated in Fig 4 of the drawings, wherein the broken line represents the position before deformation and the full linerepresents the position after deformation. Further pressure from the press following the collapsing of the central portion 35 swages the tangs 21 and22 against the front face of the diaphragm housing to permanently secure, the component parts together in centered relation. It will be readily apparent that the automatic and permanent centering which results from the construction 'and method of assembly hereinbefore described eliminates the necessity for the use of centering gauges and also reduces the number of parts and major handling operations as well as those additional supplemental operations ordinarilymequired to center the core tip and voicecoil within the air gap. 1 e

I have shown and described'what I consider to be the preferred embodiment of my invention along with suggested modified forms, and it will be obvious to those skilled in the art that other changes and modifications may be made both in the construction and in the method of assembly ofthe loud speaker Without departing from the scope of my invention as defined by the appended claims. V f

I claim: r V a 1. A permanent magnet loud speaker assembly comprising in combination, a diaphragm housing having a a central bore for receiving a diaphragm voice coil, a magnetic structure including a yoke and a magnet and a pole tip, saidpole tip having ,a'flanged extremity adapted having a depressed central portion overlying and extending axially away from the central bore in said front plate, said depressed central portion having a radially disposed and inwardly directed marginal flange defining a pole tip receiving bore therethrough, means on said front plate coacting with complementary means on said flexible member for maintaining said pole tip receiving bore concentric with said central borein said front plate, the size and configuration of said pole tip receiving here being substantially'the same as" the cross-sectional configuration of said pole tip to guide andhold the pole tip in centered relation within the air gap, said depressed central portion of said flexible member having an axial extent sufficient to coact under compression between the front plate and the pole tip flange and exert an axial force against said magnet for maintaining said pole tip, magnet and yoke in operative assembled relation, and means on said yoke formed integrally therewith and coacting with complementary means on'saidfront plate and with complementary means on said diaphragm housing to compress said flexiblemember and hold said magnetic structure in operative'assembled relation with said housing. H Q M 2. A permanent magnet loudspeaker assembly comprising in combination, a diaphragm housing having a central bore for receiving a diaphragm voice coil therethrough, a magnetic field structure having an open ended yoke supporting a magnet thereon, a pole tip having to ,seat'against an adjacent axial extremity of the magnet when assembled, a front plate detachably mounted on said yoke for mounting the magneticstructure on the diaphragm housing, said front plate having'a central bore forming an, air gap concentrically surrounding said pole tip, means for automatically centering said pole tip in concentric relation in said central bore of said front plate, said means including a resiliently'flexible member an annular flange thereon, said pole tip being supported in axially aligned relation within said yoke and on said magnet and projecting toward the open end of said yoke, a front plate for coupling the open end of the yoke to the diaphragm housing in operative relation to a diaphragm voice coil, said front plate having a bore sur rounding the'pole tip and providing an air gap therebetween for the voice coil, a non-magnetic centering member carried .by the front plate and having a central bore concentric and axially aligned with the front plate bore, projections on the rearward face of said front plate received in complementary openings in said centering member for supporting said centering member in proper position on'said'front plate, the size and configuration of said pole tip and saidcentering member bore being substantially the same to maintain the" tip in fixed'cen tered relation in the front-plate bore, said centering memher being formed of resilient-like material and having a cup-like central depression with said centering member here extending therethrough, the walls of said cup-like depression having an "axial extent suflicient to coact :under compression between said'pole tip flange and said plate to hold'said pole tip, said'magnet, a'ndsaid. yoke inoperativeassembled relation, said diaphragm housing and said front plate each having a plurality of complementary apertures spaced'similarly about their respective bores with the corresponding apertures in said front plate and said diaphragm housing being axially aligned, andspaced deformable projections on the open end of said yoke'formed complementally to the respective of said apertures and projecting through respective aligned pairs of said apertures in said front plate and diaphragm housing, the free ends of said projections on said yoke being deformed against the front face of said diaphragm housing for securing all of the components of the field structure together onthe diaphragm housing, with the pole tip positively held in centered relation in the air gap.

, References Cited in the file of this patent UNITED STATES'PATENTS' France Nov. 29, 1948