COLLAPSIBLE MOTOR OPERATED ANTENNA

Abstract: A retractable motor-driven antenna (10) of compact size and light weight capable of being supported at the top of a support tube (14). A molded plastic housing (12), (30) in part forms the drive motor. A drive transmission (34) for extending and retracting the antenna mast (15) uses a timing belt (78) and pulley wheels (61), (62) and includes an overrunning clutch (84) or energy storage and release interconnection (76) between a driven pulley wheel (62) and a hub (64) that drives a flexible cord (46) connected to the antenna mast. A switch assembly (32) within the housing includes a transducer (99) which senses rotation of the hub (64) and automatically stops the drive when the mast reaches its extended or retracted position or is obstructed.

Description: Description Collapsible Motor Operated Antenna CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of U.S. application Serial No. 366,918, filed April 9, 1982, entitled "Collapsible Motor-operated Antenna." Technical Field This invention relates to a collapsible, motor- operated, (so-called "electric") antenna, especially for automotive use. Background Art Collapsible antennas raised and lowered by electric motors are widely used on automobiles. Such antennas are typically mounted in a fender well. The power and strength required for the drive mechanism has, in the past, required a relatively bulky and heavy antenna and motor assembly, requiring substantial space and a rela¬ tively strong mounting bracket within the fender well. With the present popularity of smaller and lighter auto¬ mobiles, the available space for automotive accessories is at a premium. The space used by one accessory takes from that available for another. In addition, the weight of an automobile has a substantial effect upon its gaso¬ line mileage and substantial effort is being made to reduce the total weight of automobiles. Accordingly the need for compact and lightweight accessories, in¬ cluding motor-operated antennas, is especially great. Nevertheless, a motor-operated antenna must be rugged and powerful enough to function under the adverse condi¬ tions of vibration, snow, ice, and the like, and be low in cost and reliable in its operation. Disclosure of Invention The present invention overcomes the size and weight disadvantages of known motor-operated antennas by pro¬ vided a small, light-weight, rugged, motor-operated, collapsible antenna that is relatively low in cost. The antenna is small enough and light enough to be mounted with a minimum of bracketing. It is of a size that permits it to be mounted in a space 3 inches by 1 1/4 inches by 13 inches. In a preferred embodiment, the antenna weighs less than one pound and can be satis¬ factory mounted with top hardware only. This eli¬ minates a redundant ground connection and support. The disclosed motor driven antenna includes a sup- porting tube and a number of telescoping antenna sec¬ tions collapsible within the tube. A reversible elec¬ tric motor extends and retracts the antenna sections via a transmission having a rotatably supported nut that engages threaded portions of a flexible cord con- neeted at one end to one of the antenna sections. A compact, light-weight, drive transmission is - provided by two pulley wheels and a belt that establish a substantial speed reduction and hence allow use of a relatively small DC reversible electric motor to supply the necessary power to raise and lower the antenna sec¬ tions. One pulley wheel drives the rotary nut, which is journalled in the housing. The nut drives the threaded cord connected to the antenna sections and extending through the housing. An interconnection is provided between the pulley wheel and the nut for absorbing, storing and releasing rotary energy, or alternatively and preferably incorporates an overrunning slip clutch. The former arrangement serves as a progressive braking means at the end of antenna travel and then, after decel- erating the rotating members to a stationary condition, unwinds the system to relieve forces on the system ele¬ ments. The latter arrangement serves to allow the drive motor to continue running a short time after antenna movement stops, without overloading the motor. Both arrangements provide for a "soft start" in either direc¬ tion, requiring less starting torque from the motor. Motor energization and direction of rotation is controlled by a relay activated by a radio on/off switch. The motor is de-energized by a transducer mounted in close proximity to the nut that drives the antenna sectio The transducer senses rotation of the nut and once rota¬ tion stops, indicating the antenna is either fully retrac ted or extended, the transducer disrupts power to the motor. The preferred transducer is a Hall-effect transducer which generates a series or sequence of pulses as the nut rotates. These pulses maintain a bi-polar switch coupled to the motor in a conductive state. When the pulses stop the switch is rendered nonconductive and power to the motor is disrupted. The motor is disabled regardless of the reason rotation stops so that if, for example, the antenna cannot be extended or retracted to its full extent, the motor is not overloaded. An improved housing is provided to in part comprise the drive motor, and to enclose a motor switch and drive transmission, and to connect with one end of a support¬ ing tube that receives the telescoping antenna sections. The motor is supported beside the supporting tube, with its shaft parallel. In the preferred embodiment, the housing is a three piece housing of molded plastic. Two of the pieces form a cavity to house the drive trans¬ mission and switch and provide a through passage cen¬ trally of a boss that connects with the antenna sections and supporting tube. A threaded drive cord that extends and retracts the antenna sections passes through the passage. The third piece of the housing extends beside the boss and supporting tube from the chamber formed by the other two pieces, is generally cylindrical and houses the motor armature. The two pieces of the hous- O ing forming the chamber are of the same width as the third housing piece and the construction provides a very narrow assembly. The above and other features and advantages of the 5 invention will become more apparent from the detailed description that follows, when considered in connection with the accompanied drawings. Brief Description of Drawings Figure 1 is a side elevational view of an antenna 10 assembly.embodying the present invention; Figure 2 " is an end elevational view of the antenna of Figure 1; Figure 3 is a partial sectional view of the antenna of Figures 1 and 2, taken along the line 3-3; l ** " Figure 4 is a schematic diagram of a control cir¬ cuit for operating the motor of the antenna shown in Figures 1-3; Figure 5 is a schematic of an alternate and pre¬ ferred control circuit for operating the motor; 20 Figure 6 is a partial sectional view of the antenna of Figures 1 and 2 showing the antenna supported by a mounting surface; Figure 6A is an enlarged sectional view showing details of a retaining collar which can be removed to - *■* -' allow a replaceable antenna unit to be replaced; Figure 7 is a partial sectional view of an antenna drive showing details of the construction of that drive; Figure 8 is a sectional view taken along the line 8-8 of Figure 7; 0 Figure 9 is a sectional view showing a bottom of the antenna coupled to a plastic insulator sleeve which defines a passageway through which water flows away from the antenna drive to an exterior of the antenna assembly; 5 Figure 10 is a sectional view of an alternate em¬ bodiment of the antenna; Figure 11 is a sectional view showing the modified embodiment having a clutch engagement; and Figure 12 is a sectional view taken along the line 12-12 of Figure 10. Best Mode for Carrying Out the Invention An antenna assembly 10 embodying the invention is shown in Figures 1-3, comprising a housing 12 for a motor and drive transmission, a supporting tube 14 for supporting the assembly and for housing a collapsible antenna mast 15 comprised of telescoping sections 16, and a flexible sotrage tube 22 for a flexible cord that extends and retracts the telescoping sections 16a-d. As Figures 1 and 2 show, the housing 12 is elongated and very little wider than the supporting- tube 14. The assembly is very compact and can be mounted within a small space. As best shown in Figure 3, the housing 12 is formed of three injection molded plastic pieces 26, 28, 30, that interfit to form a strong enclosure. Pieces 26, 28 together form a cavity 31 for a printed circuit board and switch assembly 32 and a drive transmission 34. The housing piece 26 has a cylindrical boss 36 project- ing perpendicularly from a top wall 38 to connect with the supporting tube 14. The housing piece 28 has a cylindrical boss 40 extending perpendicular to a bottom wall 41, aligned with the boss 36, and accommodating connection of the flexible storage tube 22 with the housing. A central opening 42 extends through the boss 36 and a central opening 44 extends through the boss 40, each axially aligned with the other, to accommodate passage of a flexible cord 46 through the housing. Beyond the boss 36, the cord is connected to a center antenna θM r section 16a by a coupling tube 43 which is crimped about the cord 46 and center section 16a. Beyond the boss 40, the cord 46 extends into the storage tube 22. The cord is of plastic, such as Delrin and is externally threaded on two diametrically opposite por¬ tions. The cord has two diametrically opposite flat outer surfaces 46a, 46b along its length, resulting in peripherally broken threads. The cord passes through a central opening 48 of a tubular plastic insulator 45 within the boss 36, the insulator being cylindrical and slidably received within a cylindrical wall 47 within the boss 36. The insulator is partially received within the base of the fixed tube 16e and the two are secured together, as by crimping or otherwise, deforming a part of the tube into the insulator. Two opposed flat sur¬ faces 48a 48b of the plastic insulator prevent rotation of the cord 46 relative to the housing, yet provide sufficient clearance to allow free sliding of the cord. Because the inside passage 48 is subject to wear from the movement of the cord 46 it is made long relative to its diameter (several times as long) and is replaceable within the housing. To avoid risk of malfunctioning of the antenna drive from exposure to water that may find its way into the housing along or near the antenna mast, and which in cold weather can freeze and prevent relative movement between parts of the tubular drive transmission, two passages 49 (Figure 9) are provided in the boss 36. The passages open at one end 49a in communication with drains 45a, 45b in the tubular insulator 45 and at the other end 49b at the exterior of the housing below the supporting tube 14, and are inclined downwardly and outwardly. The drains 45a, 45b are located above an 0- ring seal 53 at the base of the insulator 45 between the insulator and the housing wall 38. Water leaking along the antenna 15 mast is intercepted before reach¬ ing the seal 53 and carried away through the less re¬ strictive drains 45a, 45b and passages 49 to the outside of the housing. Also, water that may find its way be- tween the telescoping antenna sections will tend to be flung from the cord 46 as it is rotated and will be received by the drains 45a, 45b. The seal 53 blocks the flow of any water that might happen to seep past the drains 45a, 45b. An upper end of the support tube 14 is securely fastened by brazing or welding to a metal mounting mem¬ ber 54, which extends through an opening in a mounting sheet 55 such as an automobile fender or the like (Fig¬ ure 6) . Top 57a and bottom 57b mounting brackets orient the antenna sections 16a-e at any desired angle with respect to the sheet 55 so that the antenna rises in the desired direction when it is extended. A tubular plastic insulator 63 fits closely around the upper end of the outer fixed antenna tube 16d and includes a circular external shoulder 63a, which rests against an upper end of the mounting member 54. With the insulator 63 in place, a retaining nut 65 having an inner threaded portion is tightened down over an outer threaded portion of the mounting member 54 until the. brackets 57a, 57b and mounting member 54 are securely mounted to the sheet 55. The antenna sections 16a-d are replaceable so that if any are broken or bent an entire unit of those sec¬ tions 16a-d may be removed and replaced. The outer section 16d is retained within the fixed antenna tube 16e by a retaining collar 67 that has a central opening 67a closely surrounding the section 16d which is too small to allow the enlarged base portion 16d (Figure 3) to pass through. The collar 67 has an internal thread 67b that engages a threaded exterior portion 16ea at the extending end of the fixed antenna tube 16e. When the collar 67 is securely fastened to the outer tube 16e, a reduced diameter portion 67c telescopes into a cylindrical recess 69 formed between the end of the outer tube 16e and the insulator 63. A circumferential flange 67d abuts the end of the insulator 63. The housing piece 26 (Figure 3) has an opening 50 in the top wall 38, in which a spherical bearing 51 is located that rotationally supports an armature shaft 52 of a motor 60 along an axis that is parallel to the longitudinal extent of the antenna mast 15. The housing piece 30 is a generally cylindrical, cup-like, member that carries a spherical bearing 56 at an upper end, in which the armature shaft 52 is jour- nailed. It also carries permanent motor field magnets 58 which are bounded by an iron shield 58a that protects the magnets 58 from exposure to extremely low tempera¬ tures which can reduce the intensity of the magnetic field they create. The drive transmission 34 has a drive pulley 61 in the cavity 31, secured to the end of the motor shaft 52, which extends through the top wall 38 into the cav¬ ity 31. A driven pulley 62 is supported laterally to one side of the drive pulley 61, between two bearings 72, 74. The bearing 72 is secured in the housing piece 26 and the bearing 74 in the housing piece 28, each adjacent a respective boss 36, 40, mounting the pulley 62 in axial alignment with the central openings 42, 44 that together form a through passage. The driven pulley 62 is of a two piece construction. A hub portion 64 (Figures 3 and 7) has top and bottom flanges 66a, 66b that rotatably support a sleeve 68 having gear teeth about its periphery. The hub 64 has a central through passage with internal threads 70 that engage the threads of the cord 46 and acts as a rotary nut to drive the cord. A timing belt 78 driven by the pulley 61 engages the teeth on the sleeve 68 which ro¬ tates the hub 64 through an overrunning clutch 84. The clutch 84 is interposed between the sleeve 68 and hub 64 so that rotation from the sleeve to the hub is trans¬ mitted through the clutch 84. The threaded relationship of the hub 64 and the cord 46 results in the longitudinal movement of the cord 46 upon rotation of the hub 64, which is restrained from axial movement by the bearings 72, 74. Thus, rota¬ tion of the hub through the transmission 34 drives the cord in a direction to extend the antenna sections or retract them, depending upon the direction of motor rotation. Because the pulley 61 is substantially smal- ler in diameter than the pulley 62, a speed reduction and power increase result. As best shown in Figure 7, the flange 66b is inte¬ gral with the hub 64. The flange 66a is keyed to the hub and secured to the flange 66b by extensions 66c that extend into holes in the flange 66b and are heat welded in place. The clutch 84 automatically decreases the force by which the hub and sleeve are interengaged when the an¬ tenna reaches the end of its travel during extension or retraction. The clutch overruns smoothly and without generation of excessive heat. This is accomplished by the use of a spring strip wrapped in a ring-like shape within an inside cylindrical surface 86 of the sleeve 68. The resilience of the spring strip causes it to engage the inside cylindrical surface 86 with sufficient force to frictionally rotate with the driven pulley under the loads experienced during extending and re¬ tracting the antenna sections when the sections are not obstructed. The spring strip encircles the hub 64 and has an inturned flange at 84a, 84b at each opposite end, re¬ ceived in a notch 88 in the hub 64. The notch is suf¬ ficiently large circumferentially to allow some peri- pheral movement of the ends of the spring, which are spaced from each other peripherally a short distance, as best illustrated in Figure 8. As illustrated in Figures 7 and 8, the spring surrounds the outside diame¬ ter of the adjacent nut portion with radial clearance. Rotation of the sleeve, transmitted to the spring through friction, causes rotation of the hub by contact of one of the flanges 84a, 84b of the spring with an end of the receiving notch 88. When rotation of the hub is stopped, as at the end of antenna travel, the frictional force of the sleeve 68 on the spring causes the spring to rotate slightly. This moves a free end of the spring toward the opposite end, reducing the diameter of the spring and relieving the frictional force against the inside diameter of the sleeve. This allows the sleeve to be rotated more free¬ ly by reduction of the frictional force between the spring and pulley,' and thereby reduces the load on the motor and the generation of heat through the relative sliding. As will be apparent from Figure 8, the spring functions identically in either direction of rotation of the driven pulley. As shown in Figure 3, the upper boss 36 receives the supporting tube 14 in closely surrounding relation. The mast is secured to and supported by the insulator 45, which compresses the O-ring seal 53. During instal¬ lation of the antenna, the mast 15 and attached cord 46 is inserted into the tube 14 so the cord 46 can be in¬ serted into the opening in the hub 64. When the mast 15 is inserted, the insulator 45 is oriented so its drains 45a, 45b communicate with the passageways 49 (Figure 9) which, in a preferred embodiment, leads away from the threads on the cord 46 to the exterior of the housing 26. The motor 60 is energized in a direction to draw the cord 46 into the hub 64 until the mast ap- proaches the position shown in Figure 3, i.e. where the retaining nut 67 screwed to the outer mast section 16e begins to seat in the recess 69 in the top insulator 63 (Figure 6) . At this time a bottom end * of the insulator 45 begins to compress or at least contact the O-ring seal 53. The mast 15 is inserted a slight distance further until the collar 67 completely seats in the recess 69, with the flange 67d abutting the end of the insulator 63. This additional movement is accomplished by com- pressing the O-ring seal between the insulator 45 and a restricted region 71 of the housing member 26 through which the hub portion of the driven pulley 62 fits. Once the mast is properly seated in place, threaded connectors 73 with pointed ends are screwed through the tube 14 and boss 36, into the insulator 45 securely positioning the mast 15 in place. In a preferred embodi¬ ment three connectors 73 are used. In the event of damage to the core sections 16a-d those sections may be replaced as outlined above without removing the outer- most section 16e which is fastened to the insulator 45. The storage tube 22 for housing the cord 46 fits inside the boss 40. The tube has a shoulder 82 on the end to retain it within the housing. The storage tube 22, being flexible, can be bent to whatever contour desired, depending upon the wheel well shape and con¬ struction in which the assembly is mounted, to provide an enclosure for the cord 46 when the antenna mast is collapsed. Alternatively, it can be preformed to a desired contour. A schematic wiring diagram of the switch assembly 32 located within the housing piece 28 is shown in Fig¬ ure 4. As shown, power from a battery such as an auto¬ mobile battery is supplied to the DC motor 60 through lines 90, 91. The direction of the motor is controlled by the polarity of the current applied through the leads, which can be changed through a double pole, double throw, center off toggle switch SW1"mounted to an automobile dashboard. A switching circuit 89 is interposed in the lead 91 by two connecting leads 93, 94. Both leads 93, 94 connect to a rectifying bridge type circuit 96 from which two lines 98, 99 of the switching circuit are connected. The bridge circuit 96 maintains a first junction 95 negative and a second junction 97 positive regardless of the polarity of the switch SW1 to allow the switching circuit to operate regardless of a change of polarity at the connections 93, 94 when current to the motor 60 is reversed. The switch circuit 89 removes the power from the motor when a preset time and current load conditions have been met, such as a short time after the motor reaches the end of its travel and a greatly increased load and hence current demand is placed upon the motor 60. The circuit 89 of Figure 4 includes diodes CRl, CR2, CR3 and CR4, three transistor Ql, Q2 and Q3 , a capacitor Cl and resistors Rl=lk, R2=10k, R3=10k, R4=10k, R5=lk and R6=l ohm, all connected as shown to conduct current to the motor 60 until a predetermined current load is applied for a predetermined time. When the switch SWl first couples the battery to the motor 60 to drive the antenna up or down the NPN power transistor Q3 conducts in a saturated state so the car battery drives the motor 60 through the 1 ohm resistor R6. Ql is turned off since the voltage across the one ohm resistor R6 is too small to bias that tran¬ sistor into conduction. When the motor experiences a greater load as it drives the antenna to an end of travel the current through the motor will increase causing the voltage across the resistor R6 to rise to the point where the transistor Ql turns on. This turn on causes the capacitor Cl to charge with a R2C1 time constant until Q2 turns on. When the transistor Q2 turns on the base voltage on Q3 drops turning Q3 off. The automobile battery now drives the motor 60 through the Ik resistor R5 instead of the 1 ohm resistor R6. The current through the motor 60 drops to a point where the motor no longer rotates. This state continues until the user toggles the switch SW1 back to its center off position. As an alternative and preferred embodiment, a mag¬ net 98 is located in the flange 66b adjacent a Hall- effect transducer 99 and associated circuitry 100 that replaces the switch circuit 89. The Hall-effect switch senses rotation of the magnet 98 which rotates in excess of 20 revolutions per second when the motor is extending or retracting the antenna. Two inputs Ml, M2 to the circuit 100 (Figure 5) are motor inputs which drive the motor in one of two directions depending upon the polarity of two inputs IP-1, IP-2 from a switch SW2. The switch SW2 is a double throw, double pole switch whose polarity is controlled by a relay (not shown) having a holding coil energized through the radio. When the coil is de-energized the switch polarity retracts the antenna and when the coil is energized the polarity is switched to extend the antenna. Thus, the antenna will extend automatically whenever the ignition and radio are both activated and will retract when either the radio or the ignition is switched off. In this embodiment the motor 60 is also energized by the car battery (not shown) so the retrac¬ tion of the antenna is accomplished even though the ignition is switched off. Assume a positive input at IP-1 which is transmit- ted through a diode and capacitor C2 to a base input of an NPN transistor Q-2, turning that transistor on. This in turn turns on one of the two power transistors Q-3, Q-4 to the right of Figure 5. When IP-1 is positive it is seen that a diode between IP-1 and the emitter of Q- 3 conducts so that transistor Q-2 turns on power transis¬ tor Q-3. Alternately when IP-1 is negative, capacitor C3 turns on Q-2 which turns on Q4 and the direction of current flow through the motor is reversed. Thus, when¬ ever the transistor Q-2 conducts, one or the other of the power transistors Q-3 or Q-4 is biased into conduc¬ tion by a signal at the base of that power transistor so that the application of either polarity signal at IP-1 and IP-2 energizes the motor 60. The signal applied to IP-1 and IP-2 is a DC signal so that after the initial receipt of that signal the two capacitors C-2 and C-3 will block the transmission of those signals to the base of the transistor Q-2. Thus, but for the presence of the Hall-effect transducer 99 and a fourth transistor Q-l, the motor would receive a signal temporarily and once the blocking effect of C- 2 and C-3- take effect, motor rotation would terminate. Once rotation of the motor begins, however, the Hall-effect transducer 99 senses magnet rotation and generates pulses at its terminal labeled #3 in Figure 5. These pulses are coupled through a capacitor C-4 and a diode to the base of the transistor Q-2. Periodic receipt of this pulse continues to bias transistor Q-2 into conduction which in turn keeps one power transistor (Q3 or Q4) turned on maintaining the motor drive signals at M-l and M-2. In the event the motor drive action OM moves the antenna to one of its limits of travel, con¬ tinued movement is no longer possible and the Hall trans¬ ducer no longer generates these pulses. Once these pulses stop the transistor Q-2 also ceases to conduct since its base emitter junction no longer has the neces¬ sary voltage across it and for a similar reason the power transistor (either Q-3 or Q-4) also stops conduct¬ ing. A transistor Q-l insures that the alternating pul- ses appearing at the base of the transistor Q-2 are generated from movement of the antenna drive and not from spurious vibrations in the car fender. The same input from either IP-1 or IP-2 which initially biases transistor Q-2 into conduction appears at the base of transistor Q-l to cause conduction in that transistor. This transistor will continue to conduct until transis¬ tor Q-2 turns off at which time transistor Q-l also turns off disabling the Hall-effect transducer. Thus, the Hall-effect transducer is only capable of transmit- ting pulses when transistor Q-l conducts and this tran¬ sistor in turn can only conduct when an input appears at either IP-1 or IP-2. Once the end of travel has been reached and the transistor Q-l is turned off, spur¬ ious vibrations to the Hall-effect transducer will never reinitiate conduction in transistor Q-2 without the appearance of the signal at IP-1 or IP-2. In summary, as long as the antenna is extending or retracting through hub rotation, either transistor Q-3 or Q-4 conducts; but upon reaching the end of travel or an obstruction, stopping the hub rotation, the con¬ ducting transistor turns off, automatically disrupting power to the motor drive. When the car radio is turned off, the inputs IP-1 and IP-2 are reversed to reverse current direction through ' the motor and the Hall-effect transducer generates pulses causing the motor to retract OM the antenna by driving the hub in the opposite direc¬ tion until the antenna is fully retracted or movement is obstructed. The circuit 100 (Figure 5) is preferable to the circuit 89 (Figure 4) since the user need not deactivate the circuit 100 after the motor 60 has fully extended or retracted the antenna. After the car ignition is turned off, IP-1 and IP-2 are still coupled to the bat¬ tery by the switch SW2 but when all transistors are turned off the circuit 100 draws only about 3 milliamps, a current the battery can supply for over 3000 hours without any problem. The Hall-effect transducer can be replaced with other means for generating a pulse train to maintain the transistor Q-2 conductive. An optical sensor might be mounted in close proximity to the flange 66b to sense rotation of a mark or irregularity in the flange. The irregularity might comprise, for example, castellations or slots in the flange 66b which would preferably trigger the optical sensor. Such an optical sensor would include an infrared radiation source which would be insensitive to dirt build-up in the vicinity of the flange 66b. An alternate antenna assembly 110 is shown in Fig¬ ures 9-11. The assembly 110 includes a housing 112, supporting tube 114, antenna mast 115 and telescoping antenna sections 116. As best shown in Figure 9, the housing 112 is formed of three injecting molded plastic pieces 126, 128, 130, that interfit to form a strong enclosure. Pieces 126, 128 together form a cavity 131 for a switch assembly 132 shown in phantom and a drive transmission 134. The housing piece 126 has a cylindri¬ cal boss 136 projecting perpendicularly from a top wall 138 to connect with a supporting tube 114. The housing piece 128 has a'cylindrical boss 40 extending perpendicu- lar to a bottom wall 141, aligned with the boss 136, O and accommodating connection of a flexible storage tube 122 with the housing. A central opening 142 extends through the boss 136 and a central opening 144 extends through the boss 140, each axially aligned with the other, to accommodate passage of a flexible cord 146 through the housing. Beyond the boss 136, the cord extends through antenna sections 116, and beyond the boss 140, it extends into the storage tube 122. The cord is of plastic, such as Delrin, and is externally threaded on two diametrically opposite portions. The cord has two diametrically op¬ posite flat outer surfaces 146a, 146b along its length, resulting in broken threads. The flat portions are adapted to be engaged by two opposed flat surfaces 148 of the central opening 142, which prevent rotation of the cord relative to the housing. Sufficient clearance is provided between the cord and the opening 142 to allow free sliding of the cord. To avoid risk of malfunctioning of the antenna drive from exposure to water that may find its way into the housing along or near the antenna mast, and which in cold weather can freeze and prevent relative movement between parts of the tubular drive transmission, a pas¬ sage 149 is provided in the boss 136. The passage opens at one end 149a in communication with the central open¬ ing 142 of the boss and at the other end 149b at the exterior of the housing, and is inclined downwardly and outwardly. The open end 149a is located just above the restricting flat sides 148, opening into a wider section of the central, opening 142 where water, leaking along the antenna mast, can be intercepted before reacting the drive elements and carried away through the less restrictive passage 149 to the outside of the housing. The housing piece 126 has an opening 150 in the top wall 138, in which a bearing 151 is located that OM rotationally supports a shaft 152 of a motor armature 154, the axis of which is parallel to the longitudinal extent of the antenna mast 115. The housing piece 130 is a generally cylindrical, cup-like, member that carries a bearing 156 at an upper end, in which the armature shaft 152 is journalled. It also carries permanent field magnets 158 and brushes 159, thereby forming, together with the armature, an electric motor 160 of compact dimensions. The drive transmission 134 has a drive pulley 161 in the cavity 131, secured to the end of the motor shaft 152, which extends through the top wall 138 into the cavity 131. A driven pulley 162 is supported laterally to one side of the drive pulley 161, between two retain- ing flanges 164, 166 above and below the driven pulley. The upper flange 164 is part of a nut 168 with internal threads 170 that engage with the threads of the cord 146. The nut 168 has a elongated tubular body 168a journalled for rotation at upper and lower ends in bear- ings 172, 174. The bearing 172 is secured in the hous¬ ing piece 126 and the bearing 174 in the housing piece 128, each adjacent a respective boss 136, 140, mounting the nut in axial alignment with the central openings 142, 144 that together form a through passage. The lower flange 166 that retains the driven pulley 162 encircles the body portion 168a of the nut. A spring 176 is. interposed between and connected to both the driven pulley 162 and the nut 168, so that rotation from the driven pulley to the nut is transmitted through the spring 176. The spring shown is a coil spring secure to the pulley and nut by insertion of bent ends into apertures of radially opposed surfaces, but could al¬ ternatively be an energy absorbing mechanism in dif¬ ferent form. The threaded relationship of the nut 168 and the cord 146 results in the longitudinal movement of the cord 146 upon rotation of the nut 168, which is restrained from axial movement by the bearings 172, 174. Thus, rotation of the nut through the transmission 174 drives the cord in a direction to extend the antenna sections or retract them, depending upon the direction of motor rotation. Because the pulley 161 is substan¬ tially smaller in diameter than the pulley 162, a speed reduction and power increase results. Rotation of the pulley 161 is transmitted to the pulley 162 through a timing belt 178. As shown in Figure 9, the upper boss 136 receives the supporting tube 114 in closely surrounding relation. A large central passage portion 142a at the outer end of the boss receives the lower portion of the antenna mast 115. The mast is secured to and supported by a base connector 180 having a threaded end 180a received in a threaded portion 142b of the central opening 142. The base connector 180 has a central opening 182 through which the cord 146 extends. It will be understood that, in the normal manner, the cord 146 is secured to the upper end section of the telescoping antenna, thereby extending and retracting all all of the sections when driven relative to the housing. The central opening 144 of the boss 140 receives a tube nipple 182 to which the tube 122 is secured. The tube extends upward into the opening 144. A shoulder 182a on the nipple retains it within the housing. The storage tube 122, being flexible, can be bent to what¬ ever contour desired, depending upon the wheel well shape and construction in which the assembly is mounted, to provide an enclosure for the cord 146 when the anten¬ na mast is collapsed. As an alternative to the spring 176 for transmit¬ ting rotation between the driven pulley 162 and the nut 168, an overrunning clutch as shown in Figures 10 and OMPI 11 can be.used between the two parts. The preferred construction automatically decreases the force by which the nut and driven pulley are interengaged when the antenna reaches the end of its travel during extension or retraction. Therefore, the clutch overruns smoothly and without generation of excessive heat. This is ac¬ complished by the use of a spring strip 184 wrapped in a ring-like shape within an inside cylindrical surface 186 of the driven pulley 162'. The resilience of the spring strip causes it to engage the inside cylindrical surface 186 with sufficient force to frictionally rotate with the driven pulley under the loads experienced dur¬ ing extending and retracting the antenna sections when the sections are not obstructed. The spring strip en- circles the nut 168' and has an inturned flange at 184a, 184b at each opposite end, received in a common notch 88 in the nut. The notch is sufficiently large circum- ferentially to allow some peripheral movement of the ends of the spring, which are spaced from each other peripherally a short distance, as best illustrated in Figure 11. As illustrated in Figures 10 and 11, the spring surrounds the outside diameter of the adjacent nut portion with radial clearance. Rotation of the pulley, transmitted to the spring through friction, causes rotation of the nut by contact of one of the flanges 184a, 184b of the spring with an end of the receiving notch 188. When rotation of the nut is stopped, as at the end of antenna travel, the frictional force of the pulley on the spring causes the spring to rotate slightly. This moves a free end of the spring toward the opposite end, reducing the diameter of the spring and relieving the frictional force against the inside diameter of the driven pulley. This allows the driven pulley to be rotated more freely by reduction of the frictional force between the spring and pulley, and thereby reduces the load on the motor and the generation of heat through the relative sliding. As will be appar¬ ent from Figure 11, the spring functions identically in either direction of rotation of the driven pulley. In a preferred embodiment of the housings 12 and 112 the length L (Figure 1) is 2.84 inches and the height H is 3.75 inches. The width W (Figure 2) is 1.20 inches and the diameter D of the supporting tube 14 is 0.8 inch. Thus, in the preferred embodiment the housing width has been kept to no more than 1.5 times greater than the width of the supporting tube and the length no more than 3.6 times greater. The over all height of the housing and antenna, except for the storage tube 22, 122 with the antenna collapsed, is 12.4 inches. The weight of the preferred embodiment is 15.9 ounces, which is sufficiently light to permit mounting with top hardware (i.e., a bracket or the like at the top of the * supporting tube 14 or 114) only. The small size of the housing occupies an extremely small volume within a wheel well of the vehicle, which is highly desirable to the automobile manufacturer. It will be apparent from Figure 3 that the housing construction, the drive trans¬ mission construction and arrangement, and the use of the housing piece 30 as a part of the motor structure, all combine to provide the extreme compactness and light weight. This is contributed to by the use of a timing belt 78 and plastic pulley wheels, in lieu of a drive train of gears, which would require additional elements, supports, and weight. While preferred embodiments of the invention have been described in detail, various modifications or al¬ terations may be made therein without departing from the spirit and scope of the invention set forth in the appended claims.

Claims: Claims 1. A retractable motor-driven antenna comprising a supporting tube, telescoping antenna sections collap- • sible within the tube, a reversible electric motor, transmission means connected between the motor and an¬ tenna sections to extend and retract the sections rela¬ tive to the tube, a control switch for controlling opera¬ tion of the motor, and a housing enclosing the motor, switch, and drive means and connected with the support¬ ing tube and antenna sections, said motor located and oriented beside the tube, with an armature shaft of the motor parallel with the tube and antenna sections, said transmission means including a drive belt and first and second speed reducing pulley wheels beneath the motor and antenna sections, the first being on the motor shaft and the second supported for rotation in the housing axially aligned with the antenna sections, an internally threaded rotary nut supported for rotation in the hous- ing coaxially with the second pulley, means between and interconnecting the nut and second pulley wheel for permitting relative restrained rotary motion between the nut and second pulley wheel under predetermined load, a flexible cord with external thread portions extending through and threadedly engaged with said nut and connected to an antenna section, and means station¬ ary with respect to the housing to prevent rotation of the cord. 2. An antenna as set forth in Claim 1 wherein said means interconnecting the second pulley wheel and nut is a spring interposed between the two. 3. An antenna as set forth in Claim 2 wherein said spring is connected to both the second pulley wheel and the nut to absorb, store and release rotary energy between the two. 4. An antenna as set forth in Claim 2 wherein said spring is positively rotated with and has a lost motion connection to one of said second pulley wheel and nut and frictionally engages the other, the lost motion connection constructed and arranged to reduce said frictional engagement when one of said second pul- ley wheel and nut rotates relative to the other. 5. An antenna as set forth in Claim 1 wherein said means interconnecting the second pulley wheel and nut is an overrunning friction clutch. 6. An antenna as set forth in Claim 1, 2, 3, 4, or 5 wherein said housing is comprised of first, second and third injection molded plastic pieces, the first and second pieces together forming a chamber in which the drive mechanism is housed, the first piece having a cylindrical boss extending parallel to the motor arma¬ ture and encircled by one end of the supporting tube, and the third piece forming a housing that in part di¬ rectly supports the motor armature and supports motor field poles, said first and second pieces being general¬ ly elongated in the direction between the motor axis and antenna sections and narrow in the transverse direc¬ tion, the width in said transverse direction being no greater than that of said third piece in said transverse direction. 7. An antenna as set forth in Claim 6 wherein the said width of said first and second pieces is no more than 50% greater and the length is no more than 3.6 times greater from the diameter of said support tube. OM 8. An antenna as set forth in Claim 7 wherein the first and second pieces each separately journal a por¬ tion of the nut for rotation and provide a passage open¬ ing through both pieces to accommodate travel of the cord. 9. An antenna as set forth in Claim 1, 2, 3, 4, or 5 wherein said housing has a through passage axially aligned with the support tube through which the cord passes. 10. An antenna as set forth in Claim 9 wherein said housing has a transverse passage from said through passage adjacent said drive transmission to the exterior of the housing. 11. An antenna as set forth in Claim 1, 2, 3, 4, or 5 wherein said control switch is bipolar, solid state, and constructed and arranged to remove power from the motor under the application of predetermined current and time conditions. 12. An antenna as set forth in claims 1, 2, 3, 4 or 5 including means to detect movement of said transmis- sion and for disabling said motor when said movement stops. 13. An antenna as set forth in Claim 1, 2, 3, 4 or 5 wherein said nut carries a magnet and said control switch is a Hall-effect switch that is momentarily en¬ abled upon receiving a signal voltage and remains en¬ abled only as long as the nut is rotated above a pre¬ determined rotational speed. 14. A motor-driven antenna comprising a supporting tube, telescoping antenna sections collapsible within the tube, a reversible electric motor, a transmission coupled to the motor including an internally threaded 5 rotary nut supported for rotation relative to said tube, means for rotating said nut, and a flexible cord con¬ nected to an antenna section and having threaded por¬ tions extending through and threadedly engaging said nut so that rotation of said nut by the motor extends 10 or retracts said cord and said antenna sections rela¬ tive to the tube, a housing enclosing the motor and transmission, means stationary with respect to the hous¬ ing to prevent rotation of the cord as said cord is driven by said nut, and means for sensing rotation of 15 said nut and for disabling said motor once said rotation stops. 15. The antenna of Claim 14 wherein said means for sensing comprises a transducer mounted in close 20 proximity to said nut, said transducer generating a sequence of pulses in response to rotation of said nut and a switch circuit responsive to said transducer for terminating energization of said reversible electric motor in response to a cessation of said sequence. ^25 16. The antenna of Claim 15 wherein said trans¬ ducer comprises a Hall-effect transducer and said switch circuit comprises a switching transistor, rendered con¬ ductive by said sequence of pulses and having an output 30 coupled to first and second power transistors for render¬ ing one or the other of said power transistors conductive to energize said motor and either extend or retract said antenna sections. 35 17. A motor-driven antenna comprising an extensible and retractable antenna, a reversible electric motor, a transmission coupling the motor to the antenna to extend and retract the antenna relative to the motor, a member movable during extension or retraction of the antenna, and means for sensing movement of said member and for disabling said motor when said movement stops. 18. The antenna of claim 17 wherein said member is carried by said transmission. 19. A motor-driven antenna comprising a housing, an antenna extensible and retractable with respect to the housing, a reversible electric motor, a transmission coupling the motor to the antenna for extending or retrac ting said antenna; said transmission including a drive member that moves relative to said housing as said antenn is extended or retracted; and means for sensing relative movement between said drive member and housing and for disabling said motor once said relative movement stops, said means for sensing including a transducer responsive to changes in electromagnetic energy impinging on said transducer with movement of said drive member. . 20. The antenna of Claim 19 wherein said transmis¬ sion includes a rotatably mounted drive member and wherei said transducer is mounted to said housing in close proximity to said drive member, said transducer generatin a sequence of pulses in response to rotation of said drive member, and said means for sensing further compri¬ sing a switch circuit responsive to said transducer for terminating energization of said reversible electric motor in response to a cessation of said sequence. 21. The antenna of Claim 20 wherein said transducer comprises a Hall-effect transducer and said switch circui comprises a switching transistor rendered conductive by said sequence of pulses and having an output coupled to first and second power transistors for rendering one or the other of said power transistors conductive to ener¬ gize said motor and either extend or retract said antenna 22. The antenna of Claim 20 wherein said transducer comprises an optical sensor for sensing an indicator rotating with the rotatably mounted drive member.

Inventors: CUSEY DAR L, REPAY LASZLO N, CUSEY, DAR, L., REPAY, LASZLO, N.
Applicants: NAT IND INC, NATIONAL INDUSTRIES, INC.
Application year: 1983
Main classification: H01Q1
IPC codes: H01Q1