WO1990009693A1 - Dispositif de securite ameliore pour appareils electriques - Google Patents

Dispositif de securite ameliore pour appareils electriques Download PDF

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Publication number
WO1990009693A1
WO1990009693A1 PCT/US1989/000802 US8900802W WO9009693A1 WO 1990009693 A1 WO1990009693 A1 WO 1990009693A1 US 8900802 W US8900802 W US 8900802W WO 9009693 A1 WO9009693 A1 WO 9009693A1
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WO
WIPO (PCT)
Prior art keywords
electrical
path
current
comprised
ground
Prior art date
Application number
PCT/US1989/000802
Other languages
English (en)
Inventor
Milton Morse
Original Assignee
Milton Morse
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US07/310,225 external-priority patent/US4951169A/en
Application filed by Milton Morse filed Critical Milton Morse
Publication of WO1990009693A1 publication Critical patent/WO1990009693A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal fluid pressure, liquid level or liquid displacement, e.g. Buchholz relays
    • H02H5/083—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal fluid pressure, liquid level or liquid displacement, e.g. Buchholz relays responsive to the entry or leakage of a liquid into an electrical appliance

Definitions

  • This invention relates, generally, to appliances and, more particularly, to appliances such as electric hair dryers, curling irons, kitchen appliances and the like which include a means for disconnecting the electrical current therein should the device become saturated with water or for any other reason where a shock hazard exits.
  • Health and beauty handheld electrical devices are generally comprised of electric hair dryers, curling irons, electric razors; kitchen devices are generally mixers, blenders, coffee makers, etc.; while handheld electric tools are generally comprised of drills, hedge-clippers, handheld saws and the like.
  • ground faulting interrupters are being used in new and renovation construction, which are expressly for the purpose of minimizing the chances of electrocution.
  • these types of devices have not been integrated into existing housing, which comprises the bulk of usage areas. Hence, safety is a problem from place to place and not merely between devices.
  • Yet another disadvantage is that encompassing standard ground fault interrupters into a handheld electrical device, such as a hair dryer or the like, requires that the case or housing must be specifically designed or re-engineered in order to accommodate the components. Thereafter, new molds must be made at considerable time and expense, and the outer profile of the handheld device must necessarily be changed.
  • Yet another object of the present invention is to produce a handheld electrical device having current interruption integral therein wherein reset, once the device has been tripped, can only be accomplished by a special tool.
  • a still further object of the present invention is to produce a handheld electrical device having a current interrupting mechanism integral therein which . is resettable only after inspection by a trained service person.
  • Yet another object of the present invention is to produce a handheld electrical device having an interrupting safety mechanism which is inexpensive to manufacture.
  • Another object of the present invention is to produce a device which adds few additional components and is easy to assemble.
  • Still a further object of the present invention is to produce a current interruption mechanism which is small and compact and may also fit into existing housing configurations and sizes.
  • Yet another object of the present invention is to produce a safety device which is retrofittable to existing designs.
  • Still another object of the present invention is to produce a safety device which will automatically and completely electrically disconnect the line cord from any interior components in the device when an electrically hazardous condition exists.
  • Another object is to hermetically seal all electrical interconnections with the line cord and the safety device.
  • a further object is to produce an invention which may fit into existing casings of handheld devices and which does not necessitate additional engineering, retooling, molding, and the like.
  • Still another object is to produce a device which does not require the change or enlargement of the outer profile of the case of the handheld electrical device.
  • Yet another object of the present invention is to produce a module which may be purchased by any manufacturer and which may therefore be manufactured as a standard item of standard size usable with any presently existing or future handheld electrical devices.
  • Another object of the present invention is to produce a device having an electrical path for driving a load therein which comprises a ground plane disposed within the device in order to provide an electrical path, a detector with an input for detecting the presence of electrical current in the ground plane and an output for producing an electrical signal after detection of the presence of electrical current in the ground plane, and a current interrupter which has an input adapted to receive the output of the detector and an output for interrupting the electrical path in the device.
  • Another object of the present invention is to produce a device a safety device for an electrical device having a first electrical path for driving a load therein and which provides an alternate ground path, comprising a ground plane disposed within the electrical device for providing an electrical ground path; a detector disposed within the electrical device, the detector comprised of a gate having a biasing lead for detecting the presence of electrical current in the ground plane, an input connected to the first electrical path, and an output and an output lead thereat for producing an electrical signal proportional to the current in the ground path; a current interruption device disposed within the electrical device, having an input adapted to receive the electrical signal of the output lead, and an output for interrupting the first electrical path in the electrical device; and an electrical storage device in series circuit relationship with the output lead.
  • Yet another object is a safety device for an electrical device having a first electrical path for driving a load therein and which provides an alternate ground path, comprising ground path disposed within the electrical device for providing an electrical ground path; a detector disposed within the electrical device, the detector comprised of a gating device having a biasing lead for detecting the presence of electrical current in the ground plane, an input connected to the first electrical path, and an output at an output lead thereat for producing an electrical signal proportional to the current in the ground path; a current interruption device disposed within theelectrical device, having an input adapted to receive the electrical signal of the output lead, and an output for interrupting the first electrical path in the electrical device; and an electrical storage device in series circuit relationship with the output lead.
  • another object of the invention is a safety cartridge for a handheld electrical device wherein the electrical device has a first electrical path for driving a load therein wherein the handheld electrical device has an alternate ground path, comprising a module disposable within a handheld electrical device for interrupting the flow of electrical current in the first electrical path in response to detecting current in the alternate ground path.
  • Figure 1 is a representational view of an electric handheld hair dryer incorporating the present invention
  • Figure 2 is a view substantially identical to Figure 1 illustrating alternate current interruption mechanisms
  • FIGS 3 and 4 show two alternate circuit configurations for effecting current interruption
  • Figure 5 shows an additional circuit configuration for effecting current interruption using a module approach.
  • FIG. 1 there is shown a diagrammatic view of the device encompassing the preferred embodiment of the present invention.
  • Shown is an electric handheld hair dryer 10.
  • the hair dryer is comprised of a barrel 12 and handle 14 housing a number of components therein.
  • an electric cord 16 At one end of handle 14 is an electric cord 16 which terminates at plug 18 and is suitable for typical household use.
  • An ON/OFF lever 20 is disposed at the base of handle 14 and may be of any suitable type such as slide, rotary or the like and may be single pole, double pole or any other suitable or desired configuration.
  • a front grill 22 which permits the passage of heated air therethrough as described more fully below.
  • a screen 24 is typically located at the rear end of barrel 12 and utilized so that foreign matter, i.e., hair, cannot be sucked into barrel 12.
  • a blower or fan is generally disposed adjacent screen 24 and takes air in through screen 24 and passes air over heating element 28. Heating element 28, in turn, heats the air before the air exits through the front grill 22.
  • a ground screen or plane 30 is used to electrically connect front grill 22 to screen 24. Further, screen/plane 30 provides a continuous electrical path throughout the interior of hair dryer 10.
  • ground screen/plane 30 any electrically conductive means to direct the current to a current interrupter device and, therefore, the ground plane 30 is not necessarily at earth “ground” potential. In this manner, should hair dryer 10 fall into water or should hair dryer 10 become wet to an unacceptable level, a ground path is provided between electrically conductive "live" areas in the hair dryer and the ground screen.
  • the electrical connection between grill and screen 22 and 24 respectively via a ground screen/plane 30 may be accomplished in any number of suitable ways, such as crimp type fits, compression type fits, soldering or welding to mention a few. Any of the live areas can and may include exposed portions of hot or neutral wires 50,52 respectively, portions of heating element 28 or blower motor 26 as well as portions of ON/OFF switch 32 having load contacts 34 therein.
  • the ground screen/plane 30 may be in a number of embodiments or configurations, although all are acceptable as long as a continuous electrically conductive ground path is provided. Accordingly, the ground screen/plane 30 may be in the form of a metal screen, or plating disposed on the interior portions of hair dryer 10, or on one side of heating insulators (not shown) which are typically disposed in barrel 12, and may be fabricated from aluminum or other type of metal foil. In this manner, a current return path is readily available between any of the electrically "live” components inside hair dryer 10 (as previously discussed) through water and hence to ground screen/plane 30.
  • ground screen/plane 30 provides another distinct and significant advantage in that present hair dryer or appliance design need not be changed from two conductor to three conductor cord sets (not shown) since present designs are most cost sensitive. For this reason I have found that provision of an Interrupt device, shown generally at 35, which is contained directly in handle 14, is appropriate.
  • the interrupt device 35 is generally comprised of two portions, an electronic components portion 37 and a mechanical interlock portion 39.
  • the function of the electronic component portion 37 is to detect and utilize electrical energy passing through or present on ground screen/plane 30.
  • the mechanical interlock 39 is used to physically disconnect incoming power via electric cord 16 to the remainder of hair dryer 10.
  • the electronic components 37 include field effect transistor (FET) 48 having its gate terminal (G) connected to a terminal of biasing battery B a , with the remaining lead of the battery B a connected to ground screen/plane 30. Therefore, the biasing battery B a will render the FET 48 conductive in the event of any current leakage between ground screen/plane 30 and elsewhere in the device 10.
  • a lithium or hearing-aid type battery B a (or other long shelf life battery) may be utilized to provide an internal POWER SUPPLY which would cause mechanical interlock 39 to be energized regardless of whether plug 18 has power applied thereto, should the hair dryer be immersed and present during a shock hazard or the like. Therefore, when plug 18 is energized, the device would have been previously tripped and no chance of electrical short or the like can be applied to the user.
  • Source terminal (S) of FET 48 is connected to hot lead 50 and to one terminal of condenser C1.
  • the remaining terminal of condenser C1 is connected to one terminal of coil 40 and to the cathode of diode D1.
  • the remaining terminal of diode D1 is connected to neutral lead 52.
  • the drain terminal (D) of FET 48 is connected directly to the remaining terminal of coil 40.
  • Coil 40 is preferably a "latch" type solenoid coil having a movable rod 42 disposed therein.
  • movable rod 42 is either an integral part of or connected to ball 36. Therefore, energization of coil 40 causes ball 36 to be urged downward.
  • rod 42 merely push ball 36 upward.
  • a stop 38 is provided to maintain ball 36 in a stationary position with ball 36 being used to bias spring-type load contacts 34 against appropriate terminals of ON/OFF switch 32. In this manner, when rod 42 is urged downward, due to electromotive force present in coil 40, ball 36 is similarly urged downwards with the result that load contacts 34 will electrically and mechanically disconnect from the contacts of ON/OFF switch 32.
  • ground screen 30 and hot wire 50 or neutral wire 52
  • current will be permitted to flow through FET 48 with the result that coil 40 will be energized.
  • a ground fault in the traditional sense is not required in order to "trip" the present invention and prevent user injury.
  • a current between ground screen/plane 30 and any electrically live component such as is present during a shock hazard, will be detected and will result in operation of interrupt device 35.
  • This shock hazard may be the result of immersion, high humidity, steel wool used during cleaning, or as a result of damage. Such damage may occur when, for example, a user tries to clean a toaster by using a knife and causes a short therein.
  • rod 42 When tripped, rod 42 will, as previously mentioned, preferably be urged downward. Further, in the preferred embodiment of the present invention, rod 42 is of an appropriate length such that after tripping it cannot and will not emerge through reset aperture/keyway 44 present in the underside of handle 14. In the preferred embodiment of the present invention, return of rod 42 to the normal position which enables load contacts 34 to be energized, cannot be accomplished except by use of reset key 46. Accordingly, reset key 46 must be passed through reset aperture/keyway 44 in order to properly reorient rod 42. Preferably, keyway 44 and hence reset key 46 are of a cross-type configuration. In this manner, reset may only be accomplished by an individual having the correct reset key.
  • interrupt device 35 it is preferred that only qualified service individuals be given a reset key, thereby adding an extra level of safety. Should interrupt device 35 trip, the user would be required to bring the device to any service center having qualified technicians who will then examine hair dryer 10 to ensure that the interior is dry, there are no damaged components, frayed wires or extraneous matter or the like, before the resetting of interrupt device 35.
  • load contacts 34 and ON/OFF switch 32 be at least moisture proof and preferably waterproof. Therefore, should a hair dryer be immersed in water, water cannot flow into the switch 32 which might permit a flow of current through switch 32 to load contacts 34 at any time.
  • a reset aperture/keyway may not be utilized with the result that a trained service technician must open up the hair dryer to ensure that they physically inspect the interior thereof and to effectuate reset of mechanical interlock 39.
  • condenser C1 is an electret which is well known and understood by one skilled in the art.
  • An electret is highly desirable since it retains a charge, absent outside electrical stimulation. In this regard, it is not necessary for condenser C1 to build a charge prior to energization of coil 40. Since the electret retains its own charge, quick energization of coil 40 is inherent. Hence, this cuts down significantly on the interrupt time of mechanical interlock 39. This is especially important since electromagnets, such as coil 40, typically have a relatively "long" energization time when viewed in terms of the time required for an electrical hazard to harm an individual. For this reason, a fast-acting FET is preferred. Additionally, should it be desired, a transient filter (not shown) may be inserted in series circuit relationship between the source terminal of FET 48 and the electrical connection to the ground screen/plane 30 should nuisance trips be a concern or a problem.
  • trigger mechanism 54 which has a number of electrical appliances, connected thereto.
  • Ground screen/plane 30 is connected via terminal A to trigger mechanism 54 while similarly terminals D and E of trigger mechanism 54 are respectively connected to coil 40.
  • Terminal B is connected to the hot lead 50 while terminal C is connected to neutral lead 52, although, for the reasons previously mentioned, terminals B and C may be reversed.
  • trigger mechanism 54 may encompass a variety of different components or alternate embodiments.
  • trigger mechanism 54 as shown in Figure 3, would supplant electronic components 37 disposed in Figure 1 while similarly trigger mechanism 54 of Figure 4 would supplant electronic components 37 of Figure 1.
  • terminal A and hence ground screen/plane 30 is connected to one terminal of condenser C2.
  • the remaining terminal of condenser C2 is connected to the gate terminal of FET 56.
  • the drain terminal of FET 56 is connected to terminal D or one terminal of coil 40.
  • Hot lead 50, terminal B, is connected to the source terminal of FET 56 and to one terminal of condenser C3.
  • condenser C3 The remaining terminal of condenser C3 is connected to the remaining lead of terminal E and hence, coil 42 and also to the cathode of diode D2.
  • the anode or diode D2 is connected to terminal C, neutral lead 52. It is preferred that condensers C2 and C3 be electrets, thereby providing a certain amount of bias to FET 56 and coil 42 for the purpose of decreasing the "trip time" of mechanical interlock 39. Additionally, by connecting to neutral lead 52, one half-cycle of delay time is eliminated since alternating current is utilized and hence lead 52 is at a high potential when lead 50 is at a low potential.
  • Figure 4 performs in a manner similar to that of Figure 3 but is, of course, somewhat simpler.
  • terminal A is connected to one terminal of condenser C4 while the remaining terminal of condenser C4 is connected to the gate terminal of FET 58.
  • the drain terminal of FET 58 is connected to the D terminal while the source terminal of FET 58 is connected to terminal B and to one terminal of condenser C5.
  • the remaining terminal of condenser C5 is connected to terminal E.
  • condensers C4 and C5 be electrets, thereby shortening the interrupt time.
  • safety cartridge 110 which is preferably a "module" containing the components indicated therein.
  • safety cartridge or module is meant the enclosure of the electrical and/or mechanical components or interlock of the present invention into a package. Therefore, the detection and current interruption portions may be packaged in a single enclosure (or separately) either in a case, or encapsulated, or any other similar means for manufacturing purposes. It is preferred, although not absolutely necessary, that safety cartridge 110 be sealed so as to be waterproofed, such as by hermetic sealing or encapsulation or the like. Therefore, the cartridge 110 may be an off-the-shelf item which is readily distributed to manufacturers of handheld electrical devices. Disposed within safety cartridge 110 is current interruption circuitry, that would make the module perform the same function as electronic and mechanical components 37, 39 previously described.
  • sensing electret 114 has one terminal connected to ground screen/plane 30 and the remaining terminal connected to the base terminal of PNP transistor 112. It is understood that an NPN, a FET or any other type of electronic triggering or gating device may be utilized without departing from the spirit and scope of the present invention.
  • the emitter of transistor 112 is connected to one terminal of the coil of magnetic trip switch 118.
  • the collector terminal of PNP transistor 112 is connected to one terminal of tripping electret 116 with the remaining terminal of tripping electret 116 connected to the remaining terminal of the coil comprising trip switch 118.
  • the collector of PNP transistor 112 is also connected to hot lead 50 inside the handheld device itself.
  • An actuating bar 120 disconnects contact arms 122 from contacts 124 during actuation of the device during an electrical hazard.
  • a reset aperature 126 is axially disposed from actuating bar 120 and is an optional item which may be used to reset the device when tripped similar to the reset aperature 44 of Figure 1.
  • Aperture 126 is preferably a seal and is adjacent sealing plug 130 disposed in the housing of the hand held electrical device 10. Therefore, reset of the cartridge after tripping may be accomplished by removal of plug 130 and the insertion of a reset tool as described above. Accordingly, the seal of aperture 126 may be replaceable or a "self sealing" type of seal.
  • each terminating point 128 is preferably hermetically sealed in the form of plugs similar to reset aperature 126.
  • seal 132 hermetically seals the joint between the cartridge 110 and cord 16.
  • any arrangement which prohibits the introduction of extraneous matter into the electrical connection is acceptable, such as waterproof type connectors which are readily available and known to one skilled in the art.
  • the entire safety cartridge 110 is preferably sold with the cord and plug 16, 18 attached thereto or electrical connection may be thereafter made by the manufacturer or assembler of the hair dryer 10.
  • the present invention produces an extremely safe device for individuals to utilize which encompasses a present design without the need for retooling and the like. Additionally, the present invention adds minimal cost while substantially increasing the safety of handheld devices such as hair dryers and the like. Further, the present invention may be encompassed into other small appliances, such as, mixers, blenders, and other kitchen-type aids.

Abstract

Dispositif de sécurité contre les électrocutions. De manière succincte, il s'agit d'un plan de terre (30) placé à l'intérieur d'un instrument (10) ou appareil électrique. Si l'instrument tombe dans l'eau ou est dangereusement mouillé, le plan de terre (30) fournit un chemin pour le courant électrique qui excite alors un dispositif d'interruption (35) contenu dans l'instrument. Ledit dispositif d'interruption (35) a la forme d'une cartouche (54) ou d'un module pouvant servir à une gamme variée d'objets. Le dispositif en question (35) est connecté électriquement avant tous les autres éléments et interconnexions électriques (26, 28) dans l'instrument ou appareil électrique (10), de sorte que, lorsque le dispositif de sécurité est actionné, toutes les autres régions sont désexcitées.
PCT/US1989/000802 1989-02-13 1989-02-28 Dispositif de securite ameliore pour appareils electriques WO1990009693A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US310,225 1989-02-13
US07/310,225 US4951169A (en) 1988-10-20 1989-02-13 Safety device for an electrical appliance

Publications (1)

Publication Number Publication Date
WO1990009693A1 true WO1990009693A1 (fr) 1990-08-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1989/000802 WO1990009693A1 (fr) 1989-02-13 1989-02-28 Dispositif de securite ameliore pour appareils electriques

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CN (2) CN1044876A (fr)
WO (1) WO1990009693A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2404832A (en) * 2003-08-09 2005-02-16 Black & Decker Inc Safety mechanism for power tool

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4270158A (en) * 1977-11-03 1981-05-26 Antonino Ravida System of protection against short circuits and fulminations
US4410925A (en) * 1982-03-22 1983-10-18 The United States Of America As Represented By The Secretary Of The Navy Ground fault detector and shutdown system
US4493975A (en) * 1982-09-30 1985-01-15 Yamada Electric Industries Co., Ltd. Hang-up hair dryer
US4687906A (en) * 1983-11-15 1987-08-18 Matsushita Electric Works, Ltd. Portable electric hair dryer with electric shock protection circuit
US4706153A (en) * 1985-06-25 1987-11-10 Matsushita Electric Works Ltd. Leakage detecting device for electrical appliance
US4709293A (en) * 1983-12-05 1987-11-24 Leviton Manufacturing Company, Inc. Shock hazard protection system
US4734822A (en) * 1985-09-13 1988-03-29 Giovanni Gilardoni Electronic circuit ensuring protection against electrical discharge, in particular for hairdryers
US4751603A (en) * 1986-07-07 1988-06-14 Simatelex Manufactory Company Limited Safety devices
US4791519A (en) * 1987-07-15 1988-12-13 North American Philips Corp. Shock protective circuit with electrical latch for small appliances

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4270158A (en) * 1977-11-03 1981-05-26 Antonino Ravida System of protection against short circuits and fulminations
US4410925A (en) * 1982-03-22 1983-10-18 The United States Of America As Represented By The Secretary Of The Navy Ground fault detector and shutdown system
US4493975A (en) * 1982-09-30 1985-01-15 Yamada Electric Industries Co., Ltd. Hang-up hair dryer
US4687906A (en) * 1983-11-15 1987-08-18 Matsushita Electric Works, Ltd. Portable electric hair dryer with electric shock protection circuit
US4709293A (en) * 1983-12-05 1987-11-24 Leviton Manufacturing Company, Inc. Shock hazard protection system
US4706153A (en) * 1985-06-25 1987-11-10 Matsushita Electric Works Ltd. Leakage detecting device for electrical appliance
US4734822A (en) * 1985-09-13 1988-03-29 Giovanni Gilardoni Electronic circuit ensuring protection against electrical discharge, in particular for hairdryers
US4751603A (en) * 1986-07-07 1988-06-14 Simatelex Manufactory Company Limited Safety devices
US4791519A (en) * 1987-07-15 1988-12-13 North American Philips Corp. Shock protective circuit with electrical latch for small appliances

Also Published As

Publication number Publication date
CN1044876A (zh) 1990-08-22
CN2057039U (zh) 1990-05-09

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