EP0553900A2

EP0553900A2 - Reinforced shank plastic key

Info

Publication number: EP0553900A2
Application number: EP93106063A
Authority: EP
Inventors: Robert E. Almblad
Original assignee: Mitsubishi Corp; Axxess Entry Technologies Inc
Current assignee: Axxess Technologies Inc
Priority date: 1987-09-03
Filing date: 1988-08-29
Publication date: 1993-08-04
Anticipated expiration: 2008-08-29
Also published as: DE3856046D1; EP0305953B1; EP0305953A2; AU2154788A; AU603250B2; NZ225897A; KR890005363A; YU168788A; PL274407A1; DE3889266T2; JPH01146086A; EP0553900A3; EP0305953A3; BR8804530A; MX172828B; DE3856046T2; CA1334797C; PT88419A; EP0553900B1; DE3889266D1

Abstract

A flat plastic operational key replaces a corresponding metal key, but is geometrically dissimilar to the metal key. The plastic key includes a shortened key alignment groove relative to the length of the key alignment groove utilized in the corresponding metal key. The shortened key alignment groove increases the volume and strength of the plastic key shank by eliminating a part of the decreased key thickness created by the penetration of the alignment groove into the shank of the plastic key.

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to molded plastic keys, whether individual keys, or plastic card/key combinations on the order of the disclosure in my U.S. Patent No. 4,677,835 dated July 7, 1987, and is more particularly concerned with reinforcing such keys against breaking at their shanks due to extraordinary twisting stress applied through the handles of the keys.

DESCRIPTION OF RELATED ART

Conventional metal keys for operating tumbler locks such as in automobiles, building doors, apparatus controls, and the like, have heretofore been generally constructed throughout the shank and bit portions, and generally the handles, or head portion of a uniform thickness common with the bit thickness. Molded plastic keys have also heretofore been constructed of substantially uniform thickness throughout their length similar to comparable metal keys.
The key bit must be fairly snuggly fitted in the key slot in the cylinder plug. Looseness of the bit in the key slot might defeat proper engagement of the lock tumblers in the key notches. On the other hand, especially in the USA, to avoid difficulty in quick insertion of the key bit into the slot, the general practice has been to provide enlarged entrance dimensions. This results in the key shank often having little if any torque support when subjected to the considerable twisting stress which may occur if for any reason there is resistance to turning of the key in the lock. Such resistance may be variously caused such as by faulty cutting of the key notches, binding due to corrosion or icing, and the like. The general tendency of the user, where there is any such resistance to turning of the key in the lock, is to apply additional torque or twisting force to the key through its handle. Metal keys will generally withstand such extraordinary twisting stress.
In a normal U.S. automobile ignition or trunk lock, only about 3.5 to 9.2 cm-kg (3 to 8 inch pounds) of torque are necessary to open the lock; non U.S. automobiles typically require higher torques. A normal uniform thickness molded plastic key will withstand up to 9.2 to 10.4 cm. kg (8 to 9 inch pounds) of torque. If greater torque is applied there is a danger of breaking the plastic key shank. An average woman can apply up to 8 to 11.5 cm-kg (7 to 10 inch pounds) of torque and an average man can apply up to 11.5 to 16 cm · kg (10 to 14 inch pounds) of torque. Therefore, there has been some key shank breakage experienced in respect to molded plastic keys having a substantially common thickness throughout their lengths.
Molded plastic keys have been disclosed in U.S. patent of Donald F. Almblad No. 4,637,236, and in U.S. Patent No. 4,677,835 of the present applicant. In both of those patents the keys are shown as of a common thickness throughout their lengths.
By way of a typical disclosure of a metal key and tumbler lock, U.S. Patent No. 4,656,851 is referred to.

SUMMARY OF THE INVENTION

The present invention provides an improved plastics material key. The plastics material key of the present invention can be used alone, or it can be used in combination with means for holding the key, such as a card-like holder. The improved plastics material key of the present invention includes means for substantially lessening the likelihood that the plastics material key will break or fail when unusual resistance or torque is encountered when the plastics material key is utilized in a lock or the like.
To this end, the plastics material key includes means for reinforcing the key. The means for reinforcing the key increases the strength of the key over that of a key which is essentially only a plastic duplicate of a standard metal key.
In an embodiment the means for reinforcing the key includes a thickening of at least a portion of the key. Although, in a preferred embodiment portions of the shank are thickened, other areas of the key may also be thickened.
The means for reinforcing the plastics material key is so constructed and arranged that it does not interfere or hinder the cutting of notches or slots in the key that are necessary along at least one side of the bit to actuate the tumblers of a lock.
The present invention also provides a plastics material key having a reinforcement member that can be used with a variety of different keys. There are a variety of different key blanks having different shank and bit constructions with varying groove configurations. The present invention provides means for reinforcing plastics material key that can utilized with a majority of the known typical key structures.
An important object of the present invention is to provide a new and improved molded key constructed from a plastics material which is strengthened against torque induced breakage of the shank portion of the key.
Another object of the present invention is to provide a new and improved molded plastic key in which the shank portion is reinforced by a thickening.
A still further object of the present invention is to provide a new and improved molded plastics material key in which the shank is strengthened through the addition to the plastic material of a strengthening material.
In accordance with the principles of the present invention, there is provided a molded key constructed from a plastics material having a handle, a shank and a bit, and in which the shank is reinforced against breakage due to unusual torque applied through the key handle when resistance to turning is encountered after the bit is inserted into a lock.
Other objects, features and advantages of the present invention will be readily apparent from the following description of preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a form of molded plastic key embodying the present invention;
Fig. 2 is an enlarged transverse sectional detail view taken substantially along the line II-II in Fig. 1 ;
Fig. 3 is an enlarged longitudinal sectional detail view taken substantially along the line III-III in Fig. 1;
Fig. 4 is a schematic illustration showing the key of Fig. 1 in a typical tumbler lock;
Fig. 5 is plan view of a modified form of molded plastic key according to the present invention;
Fig. 6 is an enlarged transfers sectional detail view taken substantially along the line VI-VI in Fig. 5;
Fig. 7 is an enlarged long ......nal sectional detailed view taken substantially along the line VII-VII in Fig. 5;
Fig. 8 is a schematic illustration showing the key of Fig. 5 in a typical tumbular lock;
Fig. 9 is a plan view of a modified form of molded plastic key enbodying a reinforced shank according to the present invention;
Fig. 10 is an enlarged transverse sectional detail view taken substantially along the line X-X in Fig. 9;
Fig. 11 is an enlarged longitudinal sectional detail view taken substantially along the line XI-XI in Fig. 9;
Fig. 12 is an enlarged side elevational view of the key in Fig. 9;
Fig. 13 is a perspective view of the reinforcing insert present in the key of Fig. 9;
Fig. 14 is a plan view of a plastic card/key combination embodying a key substantially according to Fig. 9;
Fig. 15 is a sectional detail view taken substantially along the line XV-XV of Fig. 14;
Fig. 16 is a sectional detail view taken substantially along the line XVI-XVI of Fig. 15; and
Fig. 17 is a plan view of the opposite side of the combination plastic card/key combination of Fig. 14.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

In Figs. 1-4, a modified shorter molded plastic key 27 is depicted having a handle 28, a short shank 29 and a bit 30 of a suitable length for the intended purpose. In this instance, the bit 30 has a rabbet groove 31 along only one side providing a thin longitudinal side area for receiving tumbler pin notches 32. The key 27 is especially adaptable for operating a tumbler lock 33 of the kind having an escutcheon 34 providing an entrance with lead-in surfaces 35 and 37 of wider dimensions than a key slot 38 within the plug of the lock and into which the bit 30 fits fairly snuggly.
There is provided a thickening 30 of shank 29 which stops short of the notch 32 located in the bit 30 nearest to the shank. In that portion of the thickening 39 which extends over onto the handle 28 on each face of the key, the thickening tapers toward the handle substantially as shown. The thickening 39 on each face of the key extends from side-to-side of the key as is clearly evident in Fig. 2.
As illustrated in Fig. 1, the groove g that runs along a portion of the length of the blade of the key 27, for indexing with internal configurations of a slot of a tumbler, does not extend all the way to a head end of the shank 29. This functions to reinforce the shank 29 and make it stiffer. In this regard, it should be noted that by terminating the groove g prior to an end portion of the shank 29 one can reinforce a key having such a groove. Accordingly, if desired, the shank of the plastic key can be reinforced merely by shortening the length of the groove without the necessity of making the shank thicker than remaining portions of the key. An embodiment similar to Figs. 1-4 without any thickening of the shank is shown in Figs. 5-8.
In the modification depicted in Figs. 9-13, a reinforced shank molded plastic key 40 is provided which is especially suitable for use with tumbler locks that do not have the entrances into the key slot of significantly larger cross sectional dimensions than the key slot. Such tumbler locks are especially prevelant outside of the U.S.A., particularly, in automobile locks. To this end, the key 40 has a handle 41 which may be thicker than a short shank 42 and a bit 43 of suitable length. The shank 42 and the bit 43 may have one or more longitudinally extending coding grooves 44, and at least one rabbet groove 45 along one longitudinal side of the bit 43 providing a relatively thin longitudinal side area 47 for having tumbler notches 48 cut therein to enable opening an intended tumbler lock (not shown).
In order to provide reinforcement against torque breakage of the shank 42 adjacent to the handle, a highly torque resistant reinforcing insert 48 is embodied in the shank 42 and the adjacent portion of the key handle. In a preferred construction the insert 48 comprises a thin hard metal member, desirably a hard steel stamping including a shank-reinforcing extension or finger 49 projecting from a body 50 having a head portion 51 at the opposite end from the finger 49. Rounded, i.e. radiused, corners 51 a on the head 51 and similarly rounded corners 50 on the body 50 enhance molded integrity of the plastic key 40 and the insert 48.
The reinforcing finger 49 is of a width and thickness to be received in the shank portion of the tumbler pin notch-receiving area 47. In width, the finger 49 is desirably slightly less than the width of the key area 47 so as to maintain integrity of the shank portion 42 of the key relative to the key handle 41 and the bit 43. The thickness of the reinforcing finger 49 and the key area 47 is preferably identical, and the opposite faces of the finger 49 may be exposed at the opposite faces of the area 47, whereby the finger 49 may be substantially in direct torque force contact with the entrance end of a tumbler lock key slot within which the shank 42 is received after the bit 43 has been fully inserted in the slot for operating the lock. The length and terminal end of the finger 49 are calculated to extend the maximum permissible distance into the shank and the shank end of the area 47, having regard to the nearest tumbler pin notch 48. To gain maximum extension, a slanted or oblique terminal edge 49a is provided on the finger 49 to afford a clearance relative to the nearest notch 48 that may be cut in the area 47. As best seen in Fig. 5, the diagonal terminal edge 49a terminates short of the place for the nearest notch 48, leaving a narrow separating portion of the area 47 between the edge 49a and the nearest notch 48. Through this arrangement interference from the finger 49 with efficient cutting of the notches 48 is avoided.
Desirably the body portion 50 of the insert 48 is dimensioned to be embedded within a stop portion 52 of the handle 40 and which stop portion abuts the outer end of a lock when the key shank is fully received within a lock. The head end portion 51 of the insert 48 is dimensioned to be embedded within the key handle 41 and is desirably of a length which will occupy about half the length of the handle, and is of a sufficient width for a thorough torque transmission connection between the finger 49 and the area of the handle 41 which is digitally grasped when turning the key 40 for operating a lock.
As will be noted in Fig. 9-11, the flat insert 48 is substantially thinner than the key handle 41. The shank 42, and the main thickness of the bit 43, and the body portion 50 and the head portion 51 are respectively sufficiently narrower than the stop portion 52 and the handle 41, so that as moldably imbedded in the handle 41 the insert is thoroughly integrated in the handle. Such molded integration and integrity of the key insert unit is enhanced by having the handle 41 substantially thicker than the insert 48.
Although the key 40 may be utilized independently, it may also provide the key for a plastic card/key combination as depicted in Figs. 14-17. To this end, the key 40 is located within a complementary recess 53 within a preferably generally wallet size holder 54. Desirably the recess 53 is located as conveniently near one side of the card 54 so that the remaining area of the face, or both faces, of the card can be utilized for any desired legends or indicia as schematically shown at 55.
For retaining the key 40 integrally with the card 54, integral multidirectional hinge means 55 is provided comprising a unitary part of the molding and formed from the same material as the key and the molded card, and integrally connecting an edge of the key head or handle 41 to an edge of the card 54 in the recess 53. Desirably the hinge means 55 comprises a generally elongated element which permits the key to be not only swung out of the plane of the card 54 but also to be twisted relative to the card on and about the hinge without breaking away from the card. In the preferred form, the hinge 55 comprises a generally rod shaped element which may be of cylindrical cross section and is longer than its diameter. Although the hinge 55 may be of slightly smaller diameter than the thickness of the head 41, as best seen in Fig. 11 the hinge diameter may be slightly greater than the thickness of the card 54. A reinforcement extension 57 extends from the attached end of the hinge 55 onto the adjacent portion of the card 54 and is connected to a reinforcing rib 58 which runs along the edge of the card and stiffens the card in this area against undue flexibility.

Claims

1. A flat plastic key (27) for replacing a corresponding metal key having a longitudinal axis, a standard length key alignment groove disposed in a side of the key at a location offset from the longitudinal axis by a first distance and defining a first groove length where both the plastic and metal keys are configured to actuate a rotary cylinder lock (33) having lock tumblers, an elongated key receptacle (38) disposed along a lock longitudinal axis for receiving the key (27) and a rotary lock face (34) including a substantially rectangular lock entrance slot (37) with spaced apart sidewalls, the longitudinal axis of the metal key being aligned with the longitudinal axis of the key receptable when the key is inserted in the lock, the plastic key (27) comprising:

a. a head (28) for receiving a lock actuating input torque within a force input area and having an end surface, a head thickness, a head width and a head length;

b. a shank (29) having a substantially rectangular cross section with substantially parallel sides defining a shank thickness, the shank (29) further including a width, a length, a first end surface joined to the end surface of the head (28) and a spaced apart second end surface,

c. a bit (30) having an edge surface for receiving notches to actuate the lock tumblers and including a thickness, a width and a first end surface joined to the second end surface of the shank (29); and

d. a shortened key alignment groove (g) disposed in a side of the key (27) creating a decreased key thickness along the groove (g), where the groove (g) is oriented parallel to, but offset by the first distance from the key longitudinal axis and extends along the entire length of the bit (30), but terminates at a groove termination point spaced well away from the first end of the shank (29), the shortened groove formed by decreasing the length of the key alignment groove from the first groove length to a shorter second groove length to increase the volume and strength of the plastic key shank (29) relative to the volume and strength of an exact plastic duplicate of the metal key shank by eliminating at least a part of the decreased key thickness created by penetration of the alignment groove (g) into the shank (29) of the exact plastic duplicate key (27) to thereby increase the strength of the plastic key and its capacity to transfer the input torque to the lock.

2. The plastic key of claims 1 characterized in that the shank (29) is further reinforced by increasing the spacing between the substantially parallel sides of the shank (29) to increase the shank thickness.

3. The plastic key of claim 1 or 2 characterized in that the thickness of the shank (29) is increased along the entire length of the shank (29).

4. The plastic key of one of the claims 1 to 3 characterized in that the groove termination point is located in proximity to the second end surface of the shank (29).

5. The plastic key of claim 4 characterized in that the bit (30) includes a length and that the second groove length is approximately equal to the bit (30) length.

6. The plastic key of one of claims 1 to 5 characterized in that the groove termination point is positioned within the lock (33) at a longitudinal location beyond the lock entrance slot (37) when the key (27) is fully inserted into the key receptacle (38) of the lock (27).

7. The plastic key of claim 6 characterized in that the groove termination point is located in proximity to the second end surface of the shank (29).

8. The plastic key of claim 7 characterized in that the shank (29) thickness is increased along the entire length of the shank (29).

9. The plastic key of claim 7 characterized in that a selected area of the plastic head (28) including an area located in proximity to the first end of the shank (29) is reinforced by increasing the thickness of that area of the head (28).