| Title of Invention | A PROTECTIVE DEVICE FOR A CYLINDER LOCK |
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| Abstract | The invention provides for a protective device for a cylinder lock comprising a base with gear teeth, a cover rotatable about the base and having gear teeth and a rotor mounted on the base with an intermediate gear mounted thereon, the intermediate gear meshing with the gear teeth of the base and the gear teeth of the cover to form a gear train. |
| Full Text | The invention relates to a protective device for a cylinder lock. Background of the Invention: - Cylinder locks are commonly employed and find wide spread use in industry. Most present day vehicles also employ cylinder locks. The key is inserted in the cylinder lock and turned to unlock, e.g. a vehicle ignition lock, as the case may be. There is often a requirement to prevent unauthorized access to the keyhole of the cylinder lock as also to keep the keyhole protected from external environmental factors. When vehicles employing cylinder locks, particularly two and three wheelers, are parked with the key removed from the cylinder lock, the key insertion hole of the said cylinder lock is open to the environment. This leads to the following disadvantages namely: - 1. Miscreants may insert sharp metallic objects such as scissors, wires, nails or even sticky fluids and adhesives into the keyhole, causing damage and inconvenience to the vehicle owner. An easily accessible key hole, as in the case of two and three wheelers and also open top four wheelers, provides an opportunity for thieves to tamper with the lock and drive the vehicle away. 2. A keyhole open to the environment also allows water, dust, grime and other foreign particles to enter the keyhole and jam the cylinder lock. This ingress of rainwater and dust also results in reduction in the life of the cylinder lock and sometimes failure of the lock at an inappropriate moment. To overcome these drawbacks, numerous solutions have been proposed in the prior art such as providing a shutter or cover over the cylinder lock when the vehicle is not in use. Japanese patent publication number 09-054448 describes one such cover that is easily detachable and uses a number lock system. A detachable cover however leads to complications of the cover being misplaced or lost as also the inconvenience of storing the cover on the vehicle or with the user when the vehicle is in use. To remedy the drawbacks of a detachable cover as set forth by Japanese patent publication number 09-054448, Japanese patent application number S61-5175 provides for a protective device installed on the cylinder lock such that the rotation of a rotor by a magnet key results in the movement of a shutter for opening or closing the keyhole of cylinder lock. The rotor is locked in the closed position by magnets. To release the rotor, magnets embedded on the key are used to repel the locking magnets, and rotation of the key results in the rotation of the rotor that in turn opens a shutter covering the keyhole. This type of lock gained popularity and various modifications and improvements of the protective device are now available. Present day protective devices available may be broadly classified as locks having a single rotary piece that serves both as a rotor and the shutter and, locks in which the rotor and the shutter are two separate components. The applicant's co-pending application introduces a third category in which no rotor and shutter is employed and the cover rotates about the base. However, in most protective devices, including the third type introduced by the applicant, a magnet key, or an ignition key with magnets embedded in the tongue section, is to be inserted into the magnet keyhole in the cover of the protective device and rotated by a substantial amount in order to open the ignition keyhole. Most magnet locks require the magnet key to rotate between 45 to 65 degrees to open the ignition keyhole. There is therefore a requirement to reduce the excessive rotation of the magnet key to improve user friendliness of the protective device as also to increase the life of the protective device on account of the reduced rotation of the components involved. It is a requirement and need of vehicular locks to improve user friendliness and to reduce wear of the lock. The invention aims at overcoming the aforementioned drawbacks and provides for an improved protective device in which the cover rotates about the base to cover/uncover the cylinder lock keyhole and in which reduced rotation of the magnet key is required for such a rotation. To overcome the aforementioned drawbacks the invention provides for a protective device for a cylinder lock comprising a base with gear teeth, a cover rotatable about the base and having gear teeth and a rotor mounted on the base with an intermediate gear mounted thereon, the intermediate gear meshing with the gear teeth of the base and the gear teeth of the cover to form a gear train. Brief description of the drawings: Figure 1 illustrates an exploded view of the protective device in accordance with an embodiment of the invention. Figure 2 illustrates a top view of the protective device with the magnet key inserted in accordance with an embodiment of the invention. Figure 3 illustrates a side view of the protective device of figure 2 as indicated by direction 'P'. Figure 4 illustrates a sectional view along line A-A of figure 3. Figure 5 illustrates a sectional view along line B-B of figure 4. Figure 6 illustrates a top view of the protective device in the closed position in accordance with an embodiment of the invention. Figure 7 illustrates the side view of the protective device of figure 6 as indicated by direction 'Q'. Figure 8 illustrates a sectional view along line A1-A1 of figure 7. Figure 9 illustrates a sectional view along B1-B1 of figure 8. Figure 10 illustrates a top view of the protective device in an open position. Figure 11 illustrates a top view of the protective device in the closed position. Figure 12 illustrates a sectional view along line C-C of figure 10. Figure 13 illustrates a bottom perspective view of the cover in accordance with an embodiment of the invention. Figure 14 illustrates a perspective view of the base in accordance with an embodiment of the invention. Figures 15 (a, b, c) illustrates the rotor in accordance with an embodiment of the invention. Figures 16 (a, b, c) illustrates the intermediate gear in accordance with an embodiment of the invention. Figure 17 illustrates the magnetic key in accordance with an embodiment of the invention. Detailed description of the invention For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof. The invention has been explained for a vehicle cylinder lock, but as would be obvious to a person in the art, the invention may be employed to any cylinder lock. Throughout the patent specification, a convention employed is that in the appended drawings, like numerals denote like components. The invention provides for a protective device in which the cover rotates about the base to open or close the key insertion hole of the cylinder lock. The invention provides for a protective device that does not reveal the location of key insertion hole of the cylinder lock when the cover is shut. The invention provides for a protective device that requires very little rotation of the magnet key for the ignition keyhole to be uncovered. With reference to accompanying figures, and initially to figure 1, an exploded view of the protective device in accordance with an embodiment of the invention is illustrated. The figure illustrates a protective device that is to be fitted with a cylinder lock (not shown) of a vehicle. The protective device comprises of a base (1) and a cover (20). The cover is fixed to the base in a manner that does not obstruct or restrict the rotation of the cover about the base. As shown the key (90) has magnets (92) embedded in the tongue section (91) forming a magnet key. The magnet key is inserted into the magnet key insertion recess (31) in the rotor (30) and is rotated. The rotation of the key rotates the rotor that in turn rotates the cover (20) so that the key insertion hole (21) of the cover is aligned with the key insertion hole of the cylinder lock. It is within the scope of the invention that a separate magnet key be used. In accordance with an embodiment of the invention, the cover is shown to have a key insertion hole (21) which when aligned with the key insertion hole of the cylinder lock below, will allow the key to be inserted in the cylinder lock, and a hole (22) for receiving projection (39) of rotor, which in the embodiment has been shown to be centrally located. The cover also has at least one projection (27), two in the embodiment shown, that are used to manually rotate the cover about the base from an open position in which the key insertion hole (21) is aligned with the key insertion hole of the cylinder lock to a closed position in which the key insertion hole (21) is not aligned with the corresponding insertion hole of the cylinder lock. The projections (27) provide convenience to the user, as it is not necessary to use the magnet key to shut the cover when required. The base comprises of an insertion hole (2) that is aligned with the key insertion hole of the cylinder lock below it, and a pivot (4) that houses at least one magnet for the magnet lock. The magnet lock is formed with a rotor (30) that rotates about the pivot. In the embodiment shown, the pivot is centrally located and coaxial with the central axis of the protective device. The pivot (4) has cavities (5) for housing magnets (60) that are spring loaded (61). In the closed position the spring-loaded magnets enter partly in the holes on inner side of rotor (30), thereby locking the cover from rotation. Any attempts to insert an object in the recess (31), and an attempt to rotate the rotor by such an object will be unsuccessful on account of the magnet lock on the rotor by magnets (60) housed in the pivot (4). When the magnet key is inserted in the magnet keyhole, the magnets (92) present in the tongue section of the key repel the magnets (60) locking the cover from rotation. The repulsive forces generated release the rotor from the magnet lock, and rotation of the magnet key will now result in rotation of the rotor that in turn will result in rotation of the cover. The cover is rotated such that the key insertion hole (21) is aligned with the insertion hole (2) of the base and the corresponding key insertion hole (100) of the cylinder lock below it. The invention therefore eliminates the use of a shutter for the opening or closing of the key insertion hole of the cylinder lock and also does not reveal the location of the key insertion hole of the cylinder lock when the cover is in the closed position. The device also enhances user friendliness by allowing the key insertion hole of the cylinder lock to be manually closed by rotating projections on the cover. With reference now to figure 13, a cover (20) in accordance with an embodiment of the invention is illustrated. The cover comprises of a key insertion hole (21) and a hole (22) for receiving projection (39) of rotor (30). The inner surface (28) of hole (22) mates with face (38) of rotor (30) to hold the rotor inside the cover. The magnet key-receiving hole is located centrally in the embodiment illustrated. The cover is provided with at least one guide slot (25), two in the embodiment shown, that are used to fix the cover to the base in a manner that allows rotation of the cover about the base. The guide slots receive a projection in the form of pin (80) that is fitted on to the base and enters the guide slots (25). The pin is sized so that it may easily fit within the guide slot (25) without causing any friction, and allows the cover to rotate freely. The cover is also provided with a projection (24) that serves to define and limit the rotation of the cover about the base, as also to define the movement of the cover such that the insertion hole (21) is correctly aligned with the insertion hole in the base and the cylinder lock. The projection (24) is positioned on the inner surface of the cover and fits in the guide path formed on the base that is defined by stoppers (9,10). The cover also has gear teeth (23) along the circumference of the magnet key insertion hole (22), on the bottom surface of the cover. These gear teeth may be integrally formed or may be fixed on to the cover. To reduce friction between the cover and the base by reducing the area of contact, the cover is provided with a circular guide path (26) on the inner surface as illustrated. This guide path receives steel balls (50) housed in slots (6) of the base. The balls (50) housed in the slots (6) of the base are positioned such that on assembly of the protective device they are partly within the slots (6) and partly within the guide slot (26). The cover (20) is provided with at least one projection (27), two in the embodiment shown, that is used to bring the cover to closed position. This adds flexibility to the closing operation. The cover can either be brought to closing position by rotating the magnet key (90) or by dragging it using projections (27). With reference now to figure 14, a base in accordance with an embodiment of the invention is illustrated. As shown, the base comprises an insertion hole (2) that is aligned with the corresponding key insertion hole of the cylinder lock. Base also comprises of a pivot (4) that has cavities (5) for housing magnets (60) that are spring loaded (61) for providing the necessary magnet lock between the base and the rotor. This magnet lock prevents the rotation of the rotor and thereby prevents unauthorized access to the insertion hole of the cylinder lock. The base also comprises of at least one guide slot, defined by stoppers (9, 10) along the circumference of the base. Projection (24) of the cover fits within this guide slots and its movement is restricted between stoppers (9, 10) that correspond to the open and closed position of the cover. As illustrated the base comprises of a plurality of slots (6) for partly housing steel balls (50) for reducing the area of contact between the base and the cover. In addition, the base comprises of a cavity (7) for housing the spring-loaded detent mechanism (70,71). In order to fix the cover to the base, the base is provided with a hole (11), two in the embodiment illustrated, in which pin (80) is fixed. This pin is then positioned within the guide slot (25) on the cover such that the cover is fixed to the base but rotation of the cover about the base is not hindered. The base is mounted to the cylinder lock by means of hole (12) and a screw as illustrated. The base also has gear teeth along its circumference, as a sector gear (3), for meshing with the intermediate gear (40). This gear may be integrally formed or may be fixed on to the base. With reference now to figure 15, a rotor (30) for mounting on the pivot (4) has been illustrated. The top surface of the rotor has a magnet key receiving recess (31) and a magnet key guide (32) for receiving the magnet key. The rotor also comprises of a face (38) for holding the rotor in position within the housing. The rotor has a lower hollow surface (36) that aligns with pivot (4) thereby allowing rotation of the rotor about the pivot. The bottom surface of the rotor also has at least one cavity (35), four in the embodiment shown, for receiving magnets (60) for forming the magnet lock. In the locked position, the magnets (60) are partly housed in cavities (5) of the pivot and are partly housed in the cavities (35) of the rotor. The rotor has a rotor arm (34) with a guide pin (33) for mounting an intermediate gear. The intermediate gear (40) is mounted on the pin (33) for meshing with the gears (3,23) formed on the base and the cover, thus forming a gear train. The rotor arm (34) also has cavities (37) for receiving the spring-loaded ball (70) that forms the detent mechanism. These cavities (37) correspond to the open and closed position of the cover, that is the steel ball enters a first cavity in the open position and the other cavity in the closed position. The intermediate gear (40) is mounted on pin (33) of the rotor arm. This intermediate gear meshes with gear teeth (3) formed on the base and with gear teeth (23) formed on the cover. Thus, the three gears form a planetary (epicyclic) gear train with the gear teeth (3) on base (1) acting as ring gear (Annulus), gear teeth (23) on cover (20) acting as sun gear, the intermediate gear (40) acting as planet gear and the rotor arm (34) acting as planet carrier. This planetary gear train results in large rotation of cover (20) about the base (1) with a very small rotation of rotor (30). Figures 2 and 3 illustrate a top and elevation view of the protective device with the cover in an open position, with the key insertion hole (21) aligned with the insertion hole (2) of the base and the key insertion hole of the cylinder lock as shown. As illustrated the magnet key has been inserted in the magnet key-receiving hole (22) and rotated to the open position. Figure 4 illustrates a sectional view along line A-A of figure 3. As shown projection (24) of the cover is restricted from further movement by stopper (9) of the base, which corresponds to the alignment of the insertion key hole of the cylinder lock with the insertion hole of the cover. The cover is held in this position by the detent mechanism in the form of steel ball (70) energized by spring (71) housed in the base (1) that presses into the corresponding cavity (37) on the rotor. As can also be seen from figure 4, the intermediate gear meshes with the gear (3) at a position determined by stopper (8) when the cover is in the open position Stopper (8) is given in the base to stop the rotor arm (34). This stopper is provided for additional safety to gear teeth (3, 23, and 41). In open condition, in case one tries to further rotate the rotor, the stopper will restrict such movement. With reference to figure 5 that illustrates a sectional view along line B-B of figure 4, it may be seen that magnets (60) press against the inner surface of rotor but do not enter the corresponding cavities on the inner surface of the rotor and thus do not lock the rotor and therefore the cover from rotation. Figures 6 and 7 illustrate the top and elevation view of the protective device in accordance with an embodiment of the invention in the closed position, jn this position, the key insertion hole (21) of the cover is not aligned with the corresponding insertion hole present in the base and cylinder lock. The magnet key is shown inserted in the magnet key insertion recess (31). With reference now to figure 8 that illustrates a sectional view along line A1-A1 of figure 7, it may be seen that projection (24) of the cover is now restricted by stopper (10) that limits the rotation of the cover to a position in which the insertion hole (21) of the cover is not aligned with the insertion hole of the base and cylinder lock. In the closed position as illustrated by figure 9, that is a sectional view along line B1-B1 of figure 8, the cover is locked in position by the magnets present between the base and the rotor. As shown, magnets (60) that are spring loaded (61) enter the corresponding cavities (35) present in the bottom surface of the rotor. In this position, the magnets are housed partly in cavities (5) present in pivot (4) and partly in cavities (35) present in the rotor. This prevents the rotation of the rotor and therefore the cover. The working of the protective device may be better understood with reference to figures 10 and 11 that illustrate the cover in the open and closed position respectively. In the open position as illustrated by figure 10, the insertion hole (21) is aligned with the insertion hole (2) of the base and the key insertion hole of the cylinder lock is visible. By rotating the cover using projections (27) or using magnet key (90) in the direction as shown by the arrow, the insertion hole (21) of cover (20) gets misaligned with the insertion hole (2) of base (1).The cover gets locked in this position by virtue of magnet lock. With reference now to figure 12, the detent mechanism in the form of spring loaded ball (70) is illustrated. The figure is a section along line C-C of figure 10 that illustrates the cover in the closed position. The rotor has cavities (37) formed on the inner surface thereof that receive ball (70) corresponding to the open and closed position respectively. Thus cavities (37) receive the spring-loaded ball housed in the base such that the ball partly enters one cavity in the open position and the other cavity in the closed position. This detent mechanism provides the necessary feel to the user of the protective device during opening and closing of the shutter, thereby enhancing user friendliness. As also illustrated, balls (50) housed in slots (6) reduce the area of contact between the base and the cover and thus provide for a smooth functioning of the protective device. The provision of steel balls further reduces wear of the protection device as the point of contact between the base and the cover is not stationary as the balls rotate within the slots (6) and there is no one fixed point on the ball that contacts the lower surface of the cover. Figure 17 illustrates a key (90) with magnets (92) housed in the tongue section (91) of the key. The tongue section is provided with a projection (93) in which the magnets are housed. In an embodiment of the invention, the projection (93) is given a unique shape with a corresponding shape formed in magnet key receiving recess (31) of the rotor so as to ensure that the key may be inserted in a given direction only and that the magnets of the key and the magnets of the pivot are aligned. A significant advantage of the invention is that when the lock is not in use, the position of the key insertion hole of the cylinder lock is not known. Only on insertion of the magnet key and rotation of the cover, can the location of the key insertion hole of the cylinder lock be known. Thus it is very difficult for a miscreant to ascertain the location of the key insertion hole of the cylinder lock, minimizing chances of mischief. It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention. We claim: 1. A protective device for a cylinder lock comprising a base with gear teeth, a cover rotatable about the base and having gear teeth and a rotor mounted on the base with an intermediate gear mounted thereon, the intermediate gear meshing with the gear teeth of the base and the gear teeth of the cover to form a gear train. 2. A protective device for a cylinder lock as claimed in claim 1 wherein the base comprises a pivot for housing at least one magnet. 3. A protective device for a cylinder lock as claimed in claim 1 wherein the base has cavities for housing balls that reduce area of contact between the cover and the base. 4. A protective device for a cylinder lock as claimed in claim 1 wherein the cover has a guide slot on the inner surface for receiving balls that reduce area of contact between the cover and the base. 5. A protective device for a cylinder lock as claimed in claim 2 wherein the rotor has at least one hole for receiving magnet housed in pivot. 6. A protective device for a cylinder lock as claimed in claim 1 wherein the cover has at least one guide slot for receiving a projection from base to lock the cover to the base. 7. A protective device for a cylinder lock as claimed in claim 1 wherein the base has at least one slot for receiving a projection from the inner surface of the cover to limit cover rotation.A protective device for a cylinder lock as claimed in claim 7 wherein the cover has at least one projection on the inner surface that moves within the slot of the base to limit cover rotation. 8. A protective device for a cylinder lock as claimed in claim 1 wherein the cover has at least one projection on the top surface for manually closing the cover. 9. A protective device for a cylinder lock as claimed in claim 2 wherein the rotor is mounted on the pivot. 10. A protective device for a cylinder lock as claimed in claim 1 wherein the cover has a magnet key receiving hole and a key insertion hole. 11. A protective device as claimed in claim 1 wherein the teeth of the base are integrally formed. 12. A protective device as claimed in claim 1 wherein the teeth on the cover are integrally formed. 13. A protective device for a cylinder lock as claimed in any of claim 1 or 13 wherein the gear on cover is a sector gear. 14. A protective device for a cylinder lock as claimed in claim 14 wherein the gear teeth are around the magnet key-receiving hole on the bottom surface of the cover. A protective device for a cylinder lock substantially as herein described and as illustrated by the accompanying drawings. |
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| Patent Number | 272376 | |||||||||||||||
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| Indian Patent Application Number | 1153/DEL/2006 | |||||||||||||||
| PG Journal Number | 14/2016 | |||||||||||||||
| Publication Date | 01-Apr-2016 | |||||||||||||||
| Grant Date | 30-Mar-2016 | |||||||||||||||
| Date of Filing | 09-May-2006 | |||||||||||||||
| Name of Patentee | INDIAN INSTITUTE OF TECHNOLOGY | |||||||||||||||
| Applicant Address | HAUZ KHAS, NEW DELHI-110016, INDIA. | |||||||||||||||
Inventors:
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| PCT International Classification Number | B21K 3/00 | |||||||||||||||
| PCT International Application Number | N/A | |||||||||||||||
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