US2972070A

US2972070A - Vibrator

Info

Publication number: US2972070A
Application number: US700129A
Authority: US
Inventors: Lawrence V Loverde
Original assignee: Oak Manufacturing Co
Current assignee: Oak Manufacturing Co
Priority date: 1957-12-02
Filing date: 1957-12-02
Publication date: 1961-02-14
Anticipated expiration: 1978-02-14

Description

Feb. 14, 1961 v. LOVERDE VIBRATOR Filed Dec. 2, 195'? United States Patent 2,912,070 VIBRATOR llwrence V. Loverde, Chicago, Ill., assignor to Oak Manufacturing Co., a corporation of Delaware Filed Dec. 2, 1957, Ser. No. 700,129

3 Claims. (Cl. 310-25) This invention relates to a vibrator and particularly a vibrator of the type having a reed carrying movable cqntacts for cooperation with stationary contacts. Vibrators of the above type have an armature disposed at the end of a spring reed, the armature being adapted to travel back and forth across a magnetic pole face. The vibrator has suitable windings to be actuated by direct current interrupted by contacts controlled by the vibrator to maintain the vibrator continuously in opera tion. Vibrators of this type are used to interrupt direct di'rrents and generate alternating currents which may be stepped up to suitable potential for use in equipment such as, for example, automobile radio receivers.

. In the. operation of a vibrator, it is desirable to maintain. the frequency of the vibrator substantially constant in. spite of variations of applied potential to the vibrator Winding. As a rule, an increase in potential applied to the winding for energizing the vibrator results in increased amplitude of armature travel and consequently results in a change in frequency. Such an increase in frequency is. undesirable where certain loads are present. As examples, a vibrator may provide alternating current for the motor of a phonograph or magnetic recorder and reproducer. It is desirable, therefore, to maintain the frequency of reed vibration in a vibrator substantially constant in spite of variations of energization of the vibrator winding due to variations in applied potential to such windings.

'As isv well known,. a vibrator has at least one winding for creating a magnetic field associated with a ferromagnetic circuit. The ferro-magnetic circuit necessarily an'air gap between the armature carried by the reed and the pole face past which the armature is normally adapted to travel. As a rule, the armature is carried on a steel reed and the frame of the vibrator usually has sufficient iron so that one air gap between the reed and pole face and possibly another air gap or two between the reed and the frame exists.

In accordance with this invention, means are provided for creating a magnetic shunt to the magnetic path between the pole face and vibratable armature, said magnetic shunt having a reluctance which is inversely proportional to the strength of the magnetic field created by the vibrator winding. By proper design of the magnetic shunt, compensation for variations in peak field strength due to the energizing winding may be made as a result of variations in peak value of current passing through the vibrator winding. In accordance with the invention, the reluctance of the magnetic shunt is automatically adjusted by the intensity of magnetization due to winding energization so that a new vibrator having an improved magnetic shunt will function to maintain a substantially constant armature amplitude and frequency over wide variations of applied potential to the vibrator winding.

In general, the invention contemplates the provision of a resilient term-magnetic member for cooperating with the pole piece for the purpose of diverting part of the magnetic flux which ordinarily serves to actuate the 2,972,070 Patented Feb. 14, 1961 armature of the vibrator. While the invention may be applied to different types of vibrators, it will be disclosed in connection with a common type of vibrator construction, it being understood, however, that such vibrator is exemplary.

Referring, therefore, to the drawings Fig. 1 is an elevation partly broken away of a new vibrator encased in a can, the new vibrator embodying the present invention.

Fig. 2 is a sectional elevation on broken line 2-2 of Fig. 1.

Fig. 3 is a sectional view on line 3-3 of Fig. 1.

Fig. 4 is a sectional view on line 4-4 of Fig. 1.

Fig. 5 is a perspective view of one form of magnetic shunt removed from the vibrator.

Figure 6 shows a circuit diagram illustrating the connections of the vibrator.

While the invention may be applied to any type of vibrator, for convenience the invention is shown as applied to a vibrator which is more fully disclosed and claimed in United States Patent 2,252,882, issued August 19, 1941. The vibrator comprises base 10 of suitable insulating material carrying a number of prongs 11 for cooperation with a suitable socket when the vibrator is to be plugged into a circuit. Vibrator 14 has ferro-magnetic frame 16 between the ends of which is clamped reed 17. As a rule, the ends of frame 16 may be spaced and provided with suitable insulators to create a stack for supporting fixed contacts 20 on opposite sides of reed 17. Reed 17 itself may carry movable contacts disposed on opposite sides thereof, the movable contacts being supported on suitable arms riveted or otherwise secured to the reed. The movable contacts cooperate with the stationary contacts, closure of the contacts being alternately elfected on one side or the other side of the reed in accordance with reed vibration.

Fixed contacts '20 and the movable contacts cooperating therewith generally are in a circuit including a transformer primary. Reed 17 may have a suitable driving contact thereon or movable therewith for cooperation with stationary driving contact 25 secured upon one side of frame 16. The cooperating driving contacts control energization of vibrator winding 27 disposed at bight 28 of the frame. Within winding 27 is ferro-magnetic member 30 extending axially of winding 27 toward the reed. Reed 17 carries armature 32 at the end thereof, the armature being of soft iron. Armature 32 cooperates with pole piece 33 of ferro-magnetic member 30. As shown, the pole piece is offset laterally with respect to armature 32 in the normal rest position of the reed. It is understood, of course, that the reed contacts are closed in this rest position.

As illustrated in Figure 6 (this is based upon Figure 8 of the United States patent previously referred to) winding 27 is connected through the driving contacts, including stationary contact 25, to one terminal of a source of direct current such as, for example, battery 60. The other terminal of battery 60 is connected back to the remaining terminal of winding 27. It will be noted that the remaining terminal of battery 60 is also connected to the center tap of primary 61 of transformer 62. The end terminals of primary 61 are connected to the stationary contacts of the vibrator. If the vibrator is provided with rectifying contacts, such as disclosed in the issued patent previously referred to, then the secondary of transformer 62 may be connected to other stationary vibrator contacts as more fully disclosed in said patent.

The structure so far described is conventional and upon energization of winding 27, the vibrator driving contacts, including stationary driving contact 25 will cause armature 32 to vibrate back and forth past pole piece 33. The frequency of reed operation will be detera Y minedby the stiffness of the reed andthe length thereofto a large degree. Except-afor excessive amplitude or armature movement, the frequency of vibration will remain 'gene'rally constant over-variations of amplitude? In order to control the frequency, and in accordance with the invention, there is provided at least one and preferably two'm'agnetic shunts to by-pass some magnetic flux from reed armature 32.' One shunt consists of ferromagnetic angle piece 37 having spring portion 38 andpole piece portion 40. Spring portion 38 has attaching end 41 and merges into angle portion 42. It-is desirable to increase \the flexibility of spring portion 38 and accordingly thisportion may have its width decreased. v

Attaching portion 41 of each shunt is rigidly supported at part 45 of a T-shaped bracket 46 of soft iron. Bracket 46 has attaching part 47 which may be bolted to vibrator frame 16 near winding 27. Vibrator frame 16 has slots 50 through which pole portion 40 of the-shunt extends. The end of the pole portion of the shunt is disposed in proximity to pole piece 33 of the vibrator. The shunt is shaped to clear the end of reed 17. The rest position the. magnetic circuit for saidelectromagnet, at lea'st' o ne" of each shunt may be preset by bending the shunt or by suitable washers between the attaching parts of the shunt and bracket. The shunt and bracket are attached to each other at parts 41 and 45 by aniron bolt passing through oneand threaded into the other. Other attachments may -be-used.

The-bobbin upon which winding 27 is wound is of non-magnetic material so that the magnetic shunt may complete a path from the vibrator frame to vibrator pole piece33. It will be evident that a magnetic shunt path will be provided from vibrator pole piece 33-alo'ng shuntpole portions 40 and thence to some part or'parts of the Vibrator frame. i As a rule during operation, shunts 38 will vibrate-with the'reed, the amplitude of vibration of portions however being dependent upon the peak value of the magnet-ic field generated by winding 27. The greater the peak-'value'of the field due to'winding27, the closer will pole portions 40 approach pole piece 33 of the vibrator and themore magnetic lines of force will be By proper design of the'magnetic Various means for securing a magnetic shunt to the frame may be provided. The only requirement is that i to be opened and closed during reed vibration-at which time said armature sweeps back and forth past said pole face, connections between said contacts and the winding of said electromagnet so that said vibrator may maintain itself in operation, said frame and reed forming part of magnetic shunt comprising an angle'piece of ferro rn'a'g netic material, said angle piece having a spring 'po'rtionf and a pole portion, means for rigidly attaching-said spring portion of said angle piece to said frame in 'such'ia position that said pole portion extends toward said'pole' face but stops short thereof to provide an air'gapthere between, said frame and shunt providing a ferro-rnag netic path from the pole face through part of the frame and said magneticshunt to the pole portion of said shunt adjacent the pole face, said spring portion beingizsufli ciently flexible to permit said shunt to adjustitself t6 control the size of the air gap between the pole portion whereby the reed frequency may be maintained sub stantially constant over variations in existing potential;

2. The' vibrator according to claim-'1 wherein said magnetic shunt is secured to the frame on the outside of the frame'andwherein the pole portion T extends throughaslot in the frame. I I r y I I 3. The construction according to claim 1 wherein two shunt members are provided, said shunt members being disposed on opposite sides of the pole face along the line of travel of the armature. I a 1 2,547,026 a Winkler Apr. 3; 19 5 1 p, FOREIGN PATENTS: 480,279 Canada Jan. 15,1952