EXTRACTING DEVICE FOR PLUG

Abstract: Extracting device for a plug (10) at the end of an electric cable connected to an electric appliance, which plug (10) may be plugged into a socket (16). The extracting device comprises at least one elongate, alternatingly displaceable piston (14) which has a longitudinal piston-portion located within the plug (10), which longitudinal portion and the plug (10) have a common longitudinal axis. The piston (14) has two main positions, a first main position in which the front end (14') of the piston (14) is withdrawn in relation to the outer ends of the projecting contact pins (18, 18') of the plug (10), and a second main portion, in which said front end (14') thereof is located substantially just as far in front of the front end surface of the plug (10) as the outer ends of said contact pins (18, 18'). The piston (14) has an activating device (24, 28, 26, 26') arranged thereto, which, itself, is arranged to be activated automatically and maybe by remote control, to activate, thereby, the piston (14) to effect a displacement of this from said first main position into said second main position. During said displacement the piston (14) exerts a pressure against the socket (16), so that the contact pins (18, 18') of the plug (10) are extracted from the corresponding bores (20, 20') of the socket (16).

Description: EXTRACTING DEVICE FOR PLUG This invention relates to an extracting device for a plug which may be plugged into a socket, and which is carried by an electric appliance, machine or similar devices, such as electric engine heaters in motor vehicles, battery chargers for electric vehicles and the like. If one forgets to extract a plug which has been plugged into a socket, for example by the use of an engine heater, this may lead to a powerful jerk being applied to the electric cable holding the plug. Thus the plug, cable and/or socket may be damaged. In NO patent No. 165 088 a device is disclosed, which is arranged to effect an automatic withdrawing of a plug being part of an electric heating device for motor vehicles. The withdrawing device of this heating device is very bulky, meant to be mounted in a garage, and arranged to pull the coupling up to a position at a higher level, out of the reach of children. For this purpose the known device has a weight-loaded, upward sloping, pull-biased wire for moving said electrically established coupling up to the top of a column, where the coupling no longer represents a hazard. A wire connected to the plug is subjected to an upward sloping pull to said higher coupling parking level, by means of a weight attached to the other end of the wire, and the wire is placed over a pulley at the top of the column. The device requires a column of a certain minimum height, which provides a plug-pulling device too bulky for diverse application. The object of the present invention was to eliminate or substantially alleviate the imperfections, drawbacks and restrictions on application of the state of the art, as represented by the above NO patent. The aim has essentially been achieved by means of an automatic, remotely controlled, plug-extracting device of the initially mentioned kind, having the features stated in the characterizing part of claim 1. Advantageous subordinate features, describing preferred embodiments, have been made the objects of subsequent, dependent, subordinate claims. In a plug-extracting device according to the invention is included at least one central, axially directed piston in the plug, which piston has two main positions along the longitudinal axis of the piston, namely a first, withdrawn, idle position, in which the front attacking end of the piston towards the fixed socket does not apply any push force when the contact pins of the plug are fully engaged in the insertion holes of the socket with the aim of intentionally establishing an electric connection between a plug at the end of an electric cable belonging to an electric appliance etc. and the socket fixed to the wall, or the loose extension socket; and a working position, displaced axially forwards, in which the piston through its attacking end exerts such a considerable push force against the adjacent, outward central portion of the socket that the contact pins of the plug are not able to resist the push force, but are extracted from the socket. The piston has an idle position and an activated state. The piston may be activated directly or indirectly. In one embodiment in which the object of the invention is used in an engine heater in a motor vehicle, around the piston, which consists of ferro-magnetic metal and forms a core, is wound an electric line wire for the formation of a concentric induction coil with a wire connection to earth and to the starting motor of the vehicle. In the established electric circuit may be connected a condenser arranged to accelerate the coil. When the starting motor is activated on starting the car motor, the coil about the piston receives elec- tricity from the storage battery of the vehicle. On activation, i.e. when the coil is made current carrying, the piston is subjected to a powerful axially directed displacement in the direction of the socket, whereby the plug is forced out. In another embodiment the piston is not influenced directly by the current in the coil, but indirectly, as a compression spring retains the piston in an idle stand-by position, in which the spring is kept in an idle, tensioned state by means of a transverse, elongate blocking or locking device, preferably of ferro-magnetic metal, about which is wound a corresponding line wire for the formation of a coil of the same kind as the coil around the piston according to the first embodiment. The blocking or locking means of this embodiment is spring-biased towards the blocking position. In this embodiment the piston may consist of any suitable material. The second embodiment is primarily meant to be connected to portable electrically driven appliances and tools, such as vacuum cleaners, electric lawn mowers, electric hand-held tools and similar. Such electric appliances and tools are usually plugged, by a plug at the end of a cable, into a socket in a wall, or into a socket-shaped connecting part at the end of an extension cord. When the work is finished, the user must walk to the end of, for example, the cable of the vacuum cleaner and pull the plug out. When, for example, the plug of the cable of the vacuum cleaner is plugged into said socket, the piston is displaced against the force of the spring in a direction away from the socket, while the spring is being axially compressed. The compression spring, in the form of a helical spring, is positioned in a concentric sleeve which has a bottom at its end nearest to the socket. In the opposite end of the plug is a retaining/abutment means for the adjacent end of the compression spring, and in which retaining/abutment means is formed a guiding hole for the piston. Said blocking or locking means will, when the piston is withdrawn and the compression spring is tensioned between said sleeve bottom and retaining or abutment means, under the influence of the spring adopt a pushed-out, effective blocking position, in which the blocking or locking means with its outer end portion engages behind the bottom of the sleeve, thus preventing the compression spring of the piston from expanding. In the second embodiment the blocking/locking means consists of ferro-magnetic material, and its coil has a line connection to the current carrying cables through a signal decoder. The signal decoder/receiver picks up current to the coil, and is arranged to receive a signal, which is to make it respond and axially withdraw the blocking/locking means for the release of the sleeve surrounding the compression spring, which thereby presses the piston forwards towards the socket, whereby the same course of events as by the first embodiment is repeated. The signal to the signal decoder/receiver comes from a transmitter which may be attached to the electric appliance or tool, to which the plug belongs, for example a vacuum cleaner or an electric saw. Practically, it is conceivable, in the second embodiment, that when the user of a vacuum cleaner operates a button which activates a reel for retracting and winding the cable of the vacuum cleaner, an output signal is simultaneously given from a signal transmitter in the vacuum cleaner to the signal decoder/signal receiver in the plug, to activate the blocking/locking means in order to release the piston and effect the forcing out of the contact pins of the plug from the socket. The invention will be explained in detail in the following, with reference to the exemplary embodiments illustrated in the accompanying drawings. Reference is made to the drawings, in which Figs. 1 and 2 show, in axial section, a first embodiment; Fig. 1 showing a plug-extracting device comprising a rod-shaped piston centrically arranged in a plug, which by its contact pins is positioned for immediate plugging into a socket, which may be fixed to the wall, or be at the end of an extension cord; Fig. 2, corresponding to fig. 1, but showing the plug plugged into the socket, whereby the centric piston of the plug has been pushed axially backwards to an idle stand-by position; Figs. 3 and 4 show, in axial section, a second embodiment; Fig. 3 showing the plug in the position for immediate plugging into a socket, corresponding to fig. 1; Fig. 4 showing the plug in its plugged-in position, corresponding to fig. 2; Fig. 5 shows, in axial section, a plug-extracting device according to a third embodiment, the plug being in the extracted position; Figs. 6 and 7 show, in axial section, a plug-extracting device according to a fourth embodiment; Fig. 6 showing the plug positioned for immediate plugging into a socket, corresponding to fig. 1; Fig. 7 showing the plug in the plugged-in position, corresponding to fig. 2. Referring first to figs. 1 and 2; a plug 10 has axially flush guiding holes 12, 12' in its opposite end walls 10', 10' ' for a centrically arranged, linearly formed rod-piston 14 with an outer attacking head 14 ' , which in the withdrawn, idle stand-by position of the piston 14, fig. 2, may have been retracted into a recess in the end wall surface 10'' of the socket 10, nearest to the socket 16. In fig. 2, conventional contact pins 18, 18' of the plug 10 are plugged into corresponding bores 20, 20' having inner contact sleeves 22, 22', in which the friction between the pins 18, 18' and the walls of the bores ensures the engagement as long as the piston 14 is not activated, fig. 2. An embodiment of the plug-extracting device as shown in figs. 1 and 2, may, for example, be used in engine heaters in private cars and lorries, buses and when charging storage batteries for electric cars, wheel chairs etc. In the embodiment according to figs. 1 and 2 the centric piston 14 has got a wound-on line wire for the formation of an induction coil 24, as the piston consists of ferro-magnetic metal. The coil 24 is, through two electric wires 26, 26', via a condenser 28 which is arranged to enable acceleration of the coil 24, but which may optionally be omitted, connected to earth and to the starting motor (not shown) of the motor vehicle. When the plug 10 is left, unintentionally, in its plugged-in position in the socket, in accordance with fig. 2, and starting of the motor vehicle through the starting motor is initiated, the latter will supply power to the coil 24, which has a direction of windings which thereby causes an axial displacement of the ferro-magnetic core/piston 14 in the direction towards the socket 16. Thus, the device is arranged so, that the piston 14 exerts an axial push force against the socket 16 greater than the longitudinal component of force of the frictional force between the contact pins of the plug 10 and the complementary bores of the socket 16. Thereby the plug is pushed out of the socket until the two are fully separated, fig. 1. When the motor of the motor vehicle starts, the current to the starting motor is interrupted and the coil 24 is dead. A second embodiment is shown in figs. 3 and 4, in which parts corresponding or functionally equivalent to parts according to figs. 1 and 2 are designated by the same reference numerals. Thus, the plug 10 according to figs. 3 and 4 has a piston 14 arranged thereto, which piston 14 has an attacking head 14 ' and is guided by a hole 12 * in the front end wall 10'' of the plug 10 and by a hole 12 in the rear end wall 10'. The socket 16 has, thereby, a configuration which is almost identical to that shown in figs. 1 and 2. The contact pins 18, 18' and their by friction determined engagement and retention in the bores 20, 20' of the socket 16, are exactly as in the embodiment according to figs. 1 and 2, and will consequently not be described in detail. The piston 14 has not a coil of its own arranged thereto, but is, on the other hand, provided with a compression spring in the form of a helical spring 30, which is surrounded, in its compressed state, fig. 4, by a sleeve 32, having an end wall 32', which is fixed to the piston 14. The sleeve 32, 32' will enclose a part of the length of the compression spring 30 when this is expanded, fig. 3. The compression spring 30 is suspended between the front surface of the end wall 10' and the sleeve bottom which is formed by the rear surface of the end wall 32' of the sleeve. The task of the compression spring 30 is to expand from the compressed state in fig. 4 to the state according to fig. 3, thereby pushing the plug 10 out of the socket 16 in the same way as described in connection with the embodiment in figs. 1 and 2. Before such a plug-extraction is to be actuated automatically and by remote control, the compression spring 30 must be kept in its compressed state, fig. 4. This is done by means of a spring-loaded (34) blocking means 36 extending and being displaceable in one direction transverse to the longitudinal axis of the piston 14 and the spring 30. In the withdrawn, spring- loaded, stand-by position of the extraction piston 14 and the corresponding position of the compression spring 30, fig. 4, the compression spring 34 of the blocking means 36 has moved its outer blocking end portion 36' in behind the sleeve bottom constituted by the end wall 32' of the sleeve 32. Thereby the expansion of the spring 30 is prevented and the piston 14 is retained in its withdrawn, idle position. In this embodiment it is the blocking means 36 of preferably ferro-magnetic material which is surrounded by a coil 38 of line wire, that has a signal decoder/receiver 28 arranged thereto, and through which it is connected to the current carrying conductors 50, 50' of the electric cable. The embodiment according to figs. 3 and 4 may be used with portable appliances and tools, such as vacuum cleaners, electric lawn mowers and similar electric tools. The signal decoder/receiver 28 picks up current to the coil 38 and is arranged to receive a signal making it respond. The signal comes from a transmitter (not shown) which may be attached to, for example, a vacuum cleaner. It is known within the art to use the current carrying conductors 50, 50' as such signal carriers. By a vacuum cleaner it is conceivable, practically, that when the user operates a button activating a reel for winding the cable of the vacuum cleaner, a signal is sent by said transmitter through the conductors 50, 50' and 26, 26' to a signal decoder/signal receiver 28 arranged to the plug 10. The signal decoder 28 is thus arranged to pull by the reel 38 the blocking means 36 against the spring 34. Thereby the sleeve 32 is released and the spring 30 presses the piston 14 through the sleeve 32, 32' in towards the socket 16, whereafter the push-out procedure of the plug 10 follows exactly as previously explained. Reference numeral 40 designates a housing enclosing the signal decoder/receiver 28 and the blocking means 36. Fig. 5 shows a modification of the embodiment according to figs. 1 and 2, and essentially shows another positioning of the piston's 14a' rear portion, surrounded by the coil, as it is connected to the piston 14 through a flexible rod 14a. The flexible rod 14a and the conductors 50, 50', 26, 26' may be positioned together with the flexible rod 14a within a protective tube 51. A somewhat elongate hollow body 42 has two end walls transverse to the longitudinal axis of the adjacent piston portion 14a', which end walls have one guiding hole each for said piston portion 14a 1 . The embodiment according to fig. 5 leaves more freedom of choice as to placing the coil/condenser 24, 28, which does not have to be placed at the plug 10 itself. The embodiment according to fig. 5 works in the same way as the embodiment according to figs. 1 and 2, and the way of working will not be explained again. Figs. 6 and 7 show a further embodiment which essentially corresponds to the embodiment of figs. 3 and 4, and identical parts in these figures are designated by the same reference numerals. The embodiment in figs. 6 and 7 differs from the other embodiments by having, instead of a central rod-like piston 14, 14a, an alternatingly moveable, spring- loaded tube 14B with a central longitudinal axis. The tube-shaped piston 14B has a graded portion 14B' of larger diameter (both internally and externally) , but in the example smaller wall-thickness than the remaining part of the tubular piston 14B. Thereby is formed a radially directed, annular abutment surface 14B'', which one end of the compression spring 30A bears against. The second end of the spring 30A bears supportingly against an end surface 52 ' in an annular space 52, formed in the plug 10, for the spring 30A. In the plugged-in position of the plug 10 in the socket 16, the blocking means 36 bears with its blocking end against an annular radial surface 14B''', so that the compression spring 30A is kept in compressed stand-by position as shown in fig. 7. As in the embodiment in figs. 3 and 4, the blocking means 36 consists of ferro- magnetic material and is surrounded by a coil 38 of line wire, which has a signal decoder/receiver 28 arranged thereto, and which communicates through the latter with the current carrying conductors 50, 50' in the electric cable. For the rest, this further embodiment is configured as previously described in connection with figs. 3 and 4.

Claims: C L A I M S 1. Extracting device for a plug (10) which may be plugged into a socket (16) c h a r a c t e r i z e d i n that the extracting device comprises at least one, preferably centrically located, elongate, alternatingly moveable in the plug (10), piston-like body (14; 14a; 14a') which has two main positions, a first main position in which the front end (14') of the piston¬ like body (14; 14a; 14a') is withdrawn in relation to the outer ends of the projecting contact pins (18, 18') of the plug (10) , and a second main position, in which its said front end (14'; 14B''' 1 ) is located substantially just as far in front of the front end surface of the plug (10) as the outer ends of said contact pins (18, 18'), the piston (14; 14A) having an activation device (24,28,26,26'; 30,32,34,36,38; 30A,34,36,38) arranged thereto, which is, itself, arranged to be activated in order, thereby, to activate the piston-like body (14; 14a) to effect a displacement of the latter from said first main position into said second main position, whereby the piston-like body during said displacement exerts a pressure against the socket (16), so that the contact pins (18, 18') of the plug (10) are extracted from the corresponding bores (20, 20') of the socket (16). 2. Extracting device according to claim 1, ) c h a r a c t e r i z e d i n that the piston-like body (14; 14a; 14a'), respectively a portion of same has got a wound-on electric line wire for the formation of an enclosing coil (24), whose extending conductors (26, 26') for example may be connected respectively to earth and to a starting motor of a motor vehicle, in which said extracting device has been arranged to the plug (10). 3. Extracting device according to claim 2, ) c h a r a c t e r i z e d i n that the coil (24) has a condenser (28) arranged thereto, which is arranged to accelerate the coil (24) . 4. Extracting device according to claims 1 and 2, ) c h a r a c t e r i z e d i n that the piston-like body (14a) has the form of an elongate, flexible rod or cord, but has a front longitudinal portion located within the plug (10), while the coil (24), maybe with the condenser (28) arranged thereto, may be located in considerable distance from the plug (10) . 5. Extracting device according to claim 4, ) c h a r a c t e r i z e d i n that the coil- surrounding, longitudinal portion of the elongate, flexible piston-rod-like body (14a) has a leading or guiding element (42) arranged thereto, which is formed with two longitudinally spaced guiding holes for the body (14a' ) . 6. Extracting device according to one or more of the preceding claims, ) c h a r a c t e r i z e d i n that the piston (14) is spring-loaded towards said second main position constituting the extracting position, and in which the piston (14) is retained in said first main position, constituting an idle, withdrawn, stand-by position, by means of a blocking means (36) which has an activating device (38,26,26*) arranged thereto, for releasing the p ston (14) from the blocking means (36) , which active ing means may comprise a coil (38) of line wire surrounding the blocking means (36) and whose extending end portions (26, 26') are connected to the conductors of the plug cable, while the activating device may have a signal decoder/receiver (28) arranged thereto, picking up current to the coil (38) for the axial displacement of the blocking means (36) and the release of the piston (14) for the extraction of the plug (10) from the socket (16), which signal decoder/receiver (28) is arranged to respond to a signal from a transmitter which may be arranged in a vacuum cleaner, an electric hand-held tool or other electric appliance etc. 7. Extracting device according to claim 6, ) c h a r a c t e r i z e d i n that the signal transmitter of the activating device is arranged in communication with a means which, for a purpose other than extracting a plug, is operated at the end of a working operation, for example a spring-loaded press- button on a vacuum cleaner, which is to start a rotatable reel for winding the cable of the vacuum cleaner, so that said signal transmitter, when the press-button is pressed, is influenced at the same time, to generate, thereby, a signal which is received by the signal decoder/receiver (28) of the activating device. 8. Extracting device according to claims 1, 6 or 7, ) c h a r a c t e r i z e d i n that the alternatingly moveable piston-like body is formed by an essentially tubular body (14B) whose longitudinal axis preferably is concentric with the axis of the plug (10) , and which is kept in said first main position by means of a blocking means (36) whose free blocking end engages an abutting surface (14B''') formed on the outer mantle surface of the tubular body (14B) , and that the tubular body (14B) has a compression spring (30A) arranged thereto, which is activated for the forward displacement of the tubular body (14B) when the blocking means (36) is released by means of an activating device (38,26,26'). 9. Extracting device according to claim 8, ) c h a r a c t e r i z e d i n that the essentially tubular piston-like body (14B) is supported, alternatingly displaceable, in an annular space (52) formed in the plug (10) . 10. Extracting device according to claim 9, ) c h a r a c t e r i z e d i n that said annular space (52) in the plug (10) has a front annular opening for the front end of the essentially tubular, piston- like body (14B) , which annular opening is defined between an inward, annular flange of the plug and a central cylindrical portion of the plug (10) , in which the contact pins (18, 18') with conductors (50, 50') are arranged.

Inventors: STEINHOVDEN KNUT OVE, STEINHOVDEN, KNUT, OVE
Applicants: STEINHOVDEN KNUT OVE, STEINHOVDEN, KNUT, OVE
Application year: 1997
Main classification: H01R13
IPC codes: H01R13