US2781668A - Extendable antenna - Google Patents

Description

Feb. 19, 1957 J. BERTA EXTENDABLE ANTENNA mea May 14, 195s 1 N VE NTOR BY I ATT ORN E YS United States PatentO 2,781,668 EXTENDABLE ANTENNA Joseph Berta, Fairfield, Conn., assignor to Casco Products Corporation, Bridgeport, Conn., a corporation of Connecticut Application May 14, 1953, Serial No. 355,105

11 Claims. (Cl. 711-208) This invention relates to extendable-'and retractable antennas for receiving radio waves and the like, and more particularly to antennas of this type which are actuated by a friction driving mechanism.

Friction driven antennas having telescopic sections are now in common everyday use in automobiles and other conveyances; one such antenna utilizes a flexible driving rod of plastic insulating material such as nylon (synthetic fiber-forming polymeric amide) connected to the movable antenna sections, said rod being driven by opposed yfriction wheels located on opposite sides of the rod.

I have found that when ysuch atennas are first put in use the frictional drive is adequate to take care of the load imposed by the friction and weight of the antenna sections, but that the effect of weather or other adverse conditions may cause a substantial increase in the frictional load of the telescoping sections whereby the driving friction-is insufiicient to properly operate the antenna. For example, frost on the sliding surfaces of the antenna sections, or foreign matter such as dirt, dust, gum, etc., will increase the load and the resistance to movement to a point where the friction drive is nolonger properly adjusted to effectively move the antenna sections.

An object of the present invention is to provide an improved friction drive for an extendable antenna, which is `so constituted that increased loading or resistance of the antenna sections to movement will result in increased friction of the driving mechanism, thereby to enable the drive to effectively move the antenna sections under widely varying load conditions.

In accomplishing the above object I provide an improved antenna drive comprising opposed movable members engaging the plastic driving strip of the antenna, and comprising means which automatically increases the pressure orforce exerted by the members on'the driving strip in accordance with increases in the load imposed on the drive by the antenna sections.' The movable members are preferably drive wheels, and may beeither handpowered or motor-driven, the lattermethod being illustrated and described herein.

In the specific embodiment of the invention illustrated herein each driving wheel is formed of two relatively Imovable halves engaging opposed surfaces ofthe driV ing strip, and a cam arrangement is provided which reduces the spacing between the movable halves as the resistance to turning of the driving wheel increases, thereby to cause the driving wheel to more forcefully grip the driving strip. The cam means comprises a pair of disks provided with grooves and ribs having sloping engaging surfaces by which relative rotary movement between the disks is accompanied by relative axial separating movement, oneof said disks being operatively connected with one pulley half to shift the latter axially toward the other pulley half. g A further object of the invention is to provide an improved friction drive withautomatically controlled fric tion as above set forth, whichis simpleand economical Y 2,781,668 Patented Feb. l9, V1957 2 in its construction, and effective and reliable in operation.

A feature of the invention resides in the provision of simplified pulley and cam components which are telescoping and are keyed together to enable both halves of each pulley to apply the variable driving force to the driving strip as controlled by the cam means.

Other features and advantages will hereinafter appear.

I n the accompanying drawings:

Figure l is a fragmentary side elevational view of an improved power-driven telescoping mast antenna made in accordance with the invention, portions of the antenna being broken away and/ or shown in section for the purpose of clarity of illustration.

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Fig. 2 is a horizontal sectional view taken on line 2 2 of Fig, 1.

Fig. 3 is a fragmentary sectional view taken on line 3-3 of Fig. 2.

Fig.l 4 is an exploded perspective view of a pulley assembly.

Fig. 5 is an exploded perspective view of the camming disk assembly.

The antenna shown in Fig. l comprises telescoping antenna sections 10 and 11 mounted in a tubular casing 12 having electrical terminal means 13, the casing 12 being attached to a housing 14 having an upper housing portion 15 and a lower housing portion 16, the latter including a depending extension 17 in which an electric motor (not shown) is carried.

Referring to Fig. 2, the antenna drive has a motor shaft 18 carrying a worm 19 engaging a pair of worm wheels 20 which drive shafts Z1 mounted in sleeve bearingsy 22 of the housing portion 16. The shafts 21 mount opposed friction wheels or sheaves 23 which engage a driving strip 24, preferably formed of nylon, the strip 24 being connected by a coupling 25 with the antenna section A10 for the purpose of raising and lowering the latter.

The lower casing portion 16 has a fitting 26 to which a tubular sheath 27 is secured, the fitting and sheath being arranged to receive and house the driving strip 24 when the antenna is in retracted position as shown in Fig. 1.

Each of the friction drive wheels 23 comprises a pair of relatively axially movable halves 2S and 29, the half 29 being in the form of a washer having flats 30 in its bore. The pulley half 28'includes an axially-extended shank 31 which passes through the bore of the washer 29 and has flats 32 engaging the flats 30 of the washer whereby the latter is keyed to the pulley half 28. A spacing washer 33 is carried on the shank 31 to space the -pulley half 29 from the pulley half 28. The shafts 21'of the drive are threaded and carry lock nuts 34 by whih'the pulleys or wheels 23 are secured to the shafts. f 'ln' accordance with the present invention means are provided by which the pulley halves 28 and 29 are made to grip the friction 'drive strip 24 more forcefully when the resistance of the strip to movement increases, as would be occasioned by increased load imposed by the telescoping antenna elements 10 and 11. Such increased load might be due to the formation of frost on the antenna elements, or a depositing of dirt, gum or other foreign matter which would increase the friction normally existing in the telescoping sections.

Referring to Fig. 2 the shafts 21 have reduced portions 2v1`z on which the drive wheels 23 are carried, said lreduced portions having flats 35 and carrying driving and camming disks 36 having bores 37 with flats 38 by which the disks are keyed to the reduced shank portions 21a. The disks 36 have V-grooves 39 which receive sloping-faced ribs 40 of cam disks 41 which are carried bythe Shanks 31 of the pulley halves 28. The camming disks 41 have bores 42 provided with flats 43 by which the-disks are keyed to the Shanks 31 so asto v drive the pulley halves 28,'.and 29. thereby.

Interposed between each cam disk 41 and pulley half 29 is a washer 44 which may be of metal or fiber, or of resilient rubber. The washer 44 transmits force axially from the cam disk 41 to the pulley-half 29, and normally prevents separation of the pulley halves 28 and 29 a distance greater' than that shown in Fig. 2 when the antenna is operating under normal load conditions. Por such conditions a predetermined frictional force exists between the pulley halves 2S, 29 and the friction driving strip 24, such friction being sufficient to operate the antenna section when raising or lowering the antenna. lf for any reason the antenna sections should have their relative movement impeded as by the formation of frost, gum, foreign matter, etc., which increases the friction between the sections, then the driving strip 24 would more strongly resist the driving force of the pulleys 23. This will cause relative angular movement between the pulleys and cam disk 41 on the one hand, and the driving cam disk 36 on the other hand, and due to the camming action of the ribs 40 and grooves 39 the disk 41 will be forced axially to the left as viewed in Fig. 2, thereby causing the pulley halves 29 to increase their pressure on the driving strip 24. Thus greater driving force will be imparted from the motor spindle 18 to the driving strip 24, and I have found that such greater force is adequate to take `care of increased loads on the antenna section as set forth above. In consequence, the operation of the antenna will be reliable even under the adverse conditions of use.

Moreover, the construction set forth above comprising the camming disks 36 and 41 and the pulley halves Z8 and 29, together with the ilatted and telescoping parts, is extremely simple and rugged, and will withstand severe usage. If the force-transmitting washer 44 be made of resilient rubber, then it is preferred that the cam disk 41 have a peripheral flange 41a to contain the washer 44. A somewhat yielding action is obtained by making the washer 44 resilient, which is advantageous when variations in the thickness or cross section of the drive strip 24 are encountered.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

l. In an extendable and retractable antenna, a friction drive comprising a longitudinally movable strip; a pair of opposed, spaced, movable members engaging between them and under continuous force oppositely disposed surfaces of said strip for advancing and retracting the strip; actuating means connected to one of said members; and means responsive to increased resistance to movement of the strip, for causing the movable members and strip to more forcibly engage each other so as to prevent slippage therebetween during operation of said actuating means.

2. In an extendable and retractable antenna, a friction drive comprising a longitudinally movable strip; a pair of opposed, spaced, movable members engaging between them and under continuous force oppositely disposed surfaces of said strip for advancing and retracting the strip; actuating means connected to one of said members; and means responsive to increased resistance to movement of the strip, for bringing said members closer to each other to increase the force of their engagement with the movable strip so as to prevent slippage thereon during operation of said actuating means.

3. In an extendable and retractable antenna of the type having telescoping sections, a friction drive for actuating said sections comprisingva longitudinally movable driving strip connected with a movable antenna section; a pair of opposed, spaced, movable members engaging between them under continuous force oppositely disposed surfaces of said strip for advancing and retracting the strip; actuating means connected to one of said members; and means. responsive to increased resistance to movement of the` driving strip, for causing-,the movable members and strip to more forcibly engage each other so as to prevent slippage therebetween during operation of said 'actuating means.

4. The invention as dened in claim 2 in which the spaced movable members compnse relatively axially movable parts of a friction wheel, and in which the means for bringing the members closer to each other comprises a pair of cams, one cam being connected to drive one wheel part and the other cam being connected to the said actuating means.

5. rl`he invention as defined in claim 4 in which the cams comprise disks having sloping, engaging surfaces, and in which theactuating means includes a drive shaft carrying said disks and friction wheel.

6. The invention as defined in claim l in which both of said opposed members are connected with the actuating means to be moved thereby.

7. The invention as defined in claim 1 in which there is a second pair of opposed, spaced, movable members engagingy a second set of oppositcly disposed surfaces of the driving strip under continuous force, one of said members being connected to said actuating means, and in which there is a second means responsive to increased resistance to movement of the driving strip for causing the second pair of members and strip to more forcibly engage each other during operation of the said actuating means.

8. The invention as defined in claim 7 in which all four of the opposed, movable members are connected with the actuating means to be moved thereby.

9. The invention as defined in claim 8 in which the pairs of opposed members comprise parts of two opposed friction driving wheels, and in which the means causing the said more forcible engagement comprises pairs of camming shoulders rotatable with the wheels, one shoulder of each pair being connected with the said actuating means and the other shoulders of the pairs being connected respectively with the friction drive wheels.

I0. In a friction drive for an extendable and retractable antenna of the type having a longitudinally movable strip'by which the antenna is actuated, a composite, friction drive wheel engaging said strip, said wheel having an elongate shank part and having a flange part engaging said movable strip and fixed to the shank part; a pair of disks axially movable on and keyed to the shank part, one disk constituting a part of said friction wheel and being spaced from and mounted for movement toward the flange part, said one disk engaging the movable strip and said strip extending between said flange part and one disk; a resilient washer on said shank part, interposed between and engaging said disks and transmitting force therebetween, the other of said disks having a cam means; ka driving shaft coaxial with said other disk; and a cam xed to the driving shaft, engaging the cam means of said other disk for shifting the latter against the resilient washer and forcing' said washer against said one disk, thereby to move said one disk toward the flange part and increase the' force of engagement of the friction wheel with the movable strip when the resistance of the strip to movement increases during turning of the driving shaft.

l1. In a friction drive for an extendable and retractable antenna of the type having a longitudinally movable strip by which the antenna is actuated, a composite, friction drive wheel engaging said strip, said wheel having an elongate shank part and having a flange part engaging said movable strip and tixed to the shank part; a second flange part movable axially on and keyed to said shank part, said flange parts being spaced from and movable toward each other and said strip extending between said' flange parts; a` driving shaft coaxial with said friction wheel; a cam means connected between said driving shaft and said second flange part for shifting the latter toward the first flange part in; response to turning force applied to the drivingV shaft, thereby to causethe friction wheel References Cited in the le of this patent K UNITED STATES PATENTS s 1,036,606 Geissler Aug, 27, 1912 6 Nardone Sept. 21, 1943 Wildhaber Aug. 14, 1951 Youhouse Mar. 25, 1952

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