EP0579170B1 - Armored electric resistor for washing machines, including heat-sensitive switching means for protection against overheating - Google Patents
Armored electric resistor for washing machines, including heat-sensitive switching means for protection against overheating Download PDFInfo
- Publication number
- EP0579170B1 EP0579170B1 EP93111199A EP93111199A EP0579170B1 EP 0579170 B1 EP0579170 B1 EP 0579170B1 EP 93111199 A EP93111199 A EP 93111199A EP 93111199 A EP93111199 A EP 93111199A EP 0579170 B1 EP0579170 B1 EP 0579170B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- resistor
- switching means
- electric resistor
- armored electric
- contacts
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Lifetime
Links
- 238000005406 washing Methods 0.000 title claims description 11
- 238000013021 overheating Methods 0.000 title claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000004020 conductor Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 238000003780 insertion Methods 0.000 claims description 2
- 230000037431 insertion Effects 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 239000011810 insulating material Substances 0.000 claims 3
- 230000000284 resting effect Effects 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000004308 accommodation Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 229910000743 fusible alloy Inorganic materials 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0202—Switches
- H05B1/0205—Switches using a fusible material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
- H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/78—Heating arrangements specially adapted for immersion heating
- H05B3/82—Fixedly-mounted immersion heaters
Definitions
- the present invention relates to an armored electric resistor for washing machines and the like, of the type comprising a tubular resistor protection sheath immersed in the water of a washing tank, and an element for fixing said sheath to the wall of the tank, composed of two metallic flanges with an interposed elastomeric gasket suitable to be deformed in order to adhere, for retention and sealing, to the edges of an accommodation hole formed on said wall, when the flanges are arranged mutually adjacent by means of a tightening bolt.
- the electric power supply of the resistor is subject to the control of a water level sensor which, when the tank is full, switches the power supply from the electric filling valve to the resistor, thus preventing said resistor from being supplied with power when there is either no water or the quantity thereof is insufficient.
- the resistor may be powered even in absence of water.
- the temperature of the armored resistor rises rapidly, eventually reaching high values which, besides damaging the resistor itself and the machine which uses it, can also cause the combustion of the textile material loaded in the washing tank.
- Some known systems use fuse means which are inserted in the sheath of the resistor and are electrically connected in series to said resistor. When a preset temperature threshold is reached, said means melt and interrupt the electrical continuity of the resistor, disconnecting it from the power supply.
- microswitch means interposed between at least one terminal of the resistor and the related power supply cable; a metallic rod is associated with said means and passes through the fixing element and connects to the sheath of the resistor. The metallic rod, by virtue of the thermal expansion of said sheath, actuates the button of the microswitch.
- thermostatic switches which are also inserted between at least one terminal of the resistor and the power supply line and are thermally connected to the resistor sheath by means of a metallic probe passing through the fixing element to transfer the heat of said sheath to the heat-sensitive means.
- Thermostat-controlled switch systems despite being more reliable than the preceding ones, in turn have the drawback that they have considerable thermal inertia, due to the low rate at which the probe transmits heat to the heat-sensitive means, so that their intervention is often untimely.
- the aim of the present invention is to eliminate these drawbacks and, within the scope of this general aim, the invention has the important object of providing an armored resistor with heat-sensitive switching means for protection against overheating, which is highly reliable in operation and at the same time has a low manufacturing cost.
- Another important object of the present invention is to provide an armored resistor with switching means for protection against overheating, said switching means being structured in a simple manner and not compromising the tightness of the element for fixing the resistor to the tank of washing machines or the like.
- Another objects of the invention are to provide an armored resistor with switching means for protection against overheating which are structured so as to have minimum bulk, maximum protection against accidental contacts, facilitate the electrical connection of the resistor to the power supply conductors and improve its functionality.
- a further object of the invention is to provide a resistor with connection means structured so as to prevent connection errors during the assembly of the resistor on the user machine.
- the present invention relates to an armored electric resistor with heat-sensitive switching means for protection against overheating as defined in claim 1.
- the reference numeral 10 generally designates the armored resistor; the reference numeral 11 designates the protective sheath of the resistor; and the reference numeral 12 designates the element for fixing the resistor to the tank of the washing machine.
- the fixing element 12 is constituted by two superimposed metallic flanges 13 and 14, between which an elastomeric gasket 15 is inserted; said gasket is expanded, in order to provide a retention and sealing action against the edges of the seat formed in the wall of the tank, by the tightening of a bolt 16, which clamps the plates against each other.
- a hollow container 17 is arranged above the plate 14 and is constituted by a cell made of an elastically insulating polymeric material, which is formed by two half-shells 17a and 17b joined along the median plane P of the fixing element and mutually connected by means of rivets made of plastics, which are riveted by ultrasonic means.
- Seats 18 for containing the end portions of the sheath 11, and a pair of cylindrical guides 20 are provided in the half-shells of the cell 17; said guides are arranged respectively adjacent to the seats 18, with respect to which they are inclined at an angle of approximately 8°.
- a tray 21 is also formed on the outer face of the half-shell 17b and contains and protects three male connectors 22-23-24 mutually spaced by a distance of 10 mm and suitable to receive corresponding female connectors fitted on the power supply cables and the ground cable.
- the tray 21 has a keyed insertion profile, and the profile of the female connectors is correspondingly keyed in order to avoid connection errors.
- Corresponding moving contacts 26a and 26b cooperate with fixed contacts 22a and 24a and are formed by elastically flexible metallic laminae of adequate cross-section. Each moving contact has one end electrically connected to a corresponding terminal 19 of the resistor; its other end is forced into elastic contact engagement with the corresponding fixed contact 22a or 24a respectively.
- said moving contacts are substantially S-shaped and their end is connected to the corresponding terminal 19 of the resistor by means of a forced fit providing, in a known manner, for a hole having a smaller diameter than that of said connector and is surrounded by radial cuts forming corresponding elastically deformable sectors which, when the connector is pressed, prevent the axial sliding of the moving contact.
- a corresponding pusher element 27 is aligned with each moving contact 26 below it; said pusher element is constituted by a steatite cylinder slideably contained in the corresponding cylindrical guide 20.
- Each pusher element 27 rests on the terminal disk 30 of a corresponding traction element 31 slideably contained in a respective tubular guide 32.
- a pre-loaded spring 33 is interposed between the disk 30 and the corresponding adjacent end 32a of the tubular guide 32 and is kept under tension by a fusible-weld connection 34, coupling the other end of the traction element 31 (the one opposite to the disk 30) to the corresponding end of the tubular guide 32.
- the fusible weld 34 is made of a fusible alloy with a melting point of approximately 200°C, with a variation of plus or minus 10°C depending on the nature and proportion of the metals composing the alloy.
- the described safety system remains inactive (figure 3), whereas in case of absence of water, when the temperature of the sheath 11 slightly exceeds 200°C the welds 34 melt and release the traction elements 31. This is followed by the sudden extension of the springs 33 which, by acting on the pushers 27, cause the rapid opening of the corresponding moving contacts 26 (figure 4).
- the tension of the spring 33 is chosen so that it is sufficiently higher than the tension applied by the moving contact lamina 26 on the respective fixed contact, so as to ensure the complete separation of said moving contact from the corresponding fixed contact.
- the end 32a of the tubular guide 32, adjacent to the disk 30, is cup-shaped, so as to receive an elastomeric gasket 36 on which the spring 33 contrasts, deforming said gasket so that it adheres by forced contact engagement against the traction element 31 in order to seal against any leakage of water along the guide 32.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Adjustable Resistors (AREA)
- Resistance Heating (AREA)
- Thermistors And Varistors (AREA)
- Fuses (AREA)
- Thermally Actuated Switches (AREA)
Description
Claims (8)
- An armored electric resistor (10) for washing machines, comprising a tubular resistor protection sheath (11) adapted to be immersed in the washing tank of the washing machine, an element (12) for fixing said sheath to the wall of the tank and heat-sensitive switching means for protection against overheating, said switching means including fixed (22a, 24a) and movable (26a, 26b) contacts, normally closed by elastic engagement, and pusher elements (27) for the quick opening of said contacts, characterized in that said fixed contacts (22a, 24a) are supported by connectors (22, 24) for connection to the power supply line and said movable contacts (26a, 26b) are supported by terminals (19) of the resistor, said pusher elements (27) each being controlled by a respective pre-loaded elastic means (33) which is, in the closed position of said switching means, kept under tension by a traction element (31), each of said traction elements (31) being directly and rigidly coupled, so as to prevent movements, to a fusible-weld stop element (34) made of fusible material in contact with said sheath (11) of the resistor, said traction elements (31) being each slideably contained in a respective tubular guide (32); each pusher element (27) being constituted by a cylinder made of insulating material resting on a disk (30) arranged at one end of the corresponding traction element (31); each of said pre-loaded elastic means (33) being a pre-loaded spring interposed between said disk (30) and the adjacent end (32a) of the corresponding tubular guide (32) and being kept under tension by said fusible-weld stop element (34) arranged directly between the other end of said traction element (31) and the corresponding end of the tubular guide (32); each fusible-weld stop element (34) being kept in contact with the sheath (11) of the resistor by a metal strap (35) for heat exchange.
- An armored electric resistor according to claim 1, characterized in that said fixed (22a, 24a) and movable (26a, 26b) contacts are contained in a hollow container made of insulating material associated with said element (12) for fixing the resistor and formed by mutually opposite half-shells (17a, 17b) which are mutually coupled.
- An armored electric resistor according to claim 2, characterized in that said half-shells (17a, 17b), which form the hollow container, are internally provided with a pair of containment seats (18) for said terminals (19) of the resistor and with a pair of guides (20) for said movable cylinders (27) made of insulating material, said cylinders guides being inclined with respect to said containment seats (18).
- An armored electric resistor according to claim 2, characterized in that one of said half-shells (17b) which forms the hollow container is externally provided with a tray (21) having a keyed insertion profile for the containment and protection of a set of three male type connectors (22, 23, 24) adapted to receive female type connectors with a corresponding keyed profile which are fitted onto the power supply and ground conductors.
- An armored electric resistor according to claim 4, characterized in that said male type connectors (22, 24), adapted to receive said female type connectors of the power supply cables, extend inside the hollow container (17a, 17b) and form, with an extension (24a, 26a), the pair of fixed contacts of said switching means.
- An armored electric resistor according to claim 4, characterized in that said male type connector (23), adapted to receive said female type connector of the ground conductor, extends with an offset portion (23a) entering a slot (25) of an upper flange (14) of said fixing element (12), to which it is connected by riveting or upsetting.
- An armored electric resistor according to claim 1, characterized in that said movable contacts (26a, 26b) of the switching means are each formed by an elastically flexible lamina having one end rigidly couple to the corresponding terminal (19) of the resistor (10).
- An armored electric resistor according to claim 1, characterized in that said end of the tubular guide (32a), adjacent to said disk (30) of said traction element (31) is cup-shaped and contains an elastomeric gasket (36) on which said pre-loaded spring (33) contrasts, deforming said gasket (36) and making it adhere to said traction element (31) in order to seal against water leaks.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITTO920599A IT1257915B (en) | 1992-07-14 | 1992-07-14 | ARMORED ELECTRIC RESISTANCE FOR WASHING MACHINES AND SIMILAR, INCORPORATING THERMAL SENSITIVE MEANS OF PROTECTION AGAINST OVER TEMPERATURES |
ITTO920599 | 1992-07-14 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0579170A2 EP0579170A2 (en) | 1994-01-19 |
EP0579170A3 EP0579170A3 (en) | 1994-02-02 |
EP0579170B1 true EP0579170B1 (en) | 1998-05-20 |
Family
ID=11410606
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93111199A Expired - Lifetime EP0579170B1 (en) | 1992-07-14 | 1993-07-13 | Armored electric resistor for washing machines, including heat-sensitive switching means for protection against overheating |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0579170B1 (en) |
DE (1) | DE69318630T2 (en) |
ES (1) | ES2116370T3 (en) |
IT (1) | IT1257915B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19505621A1 (en) * | 1995-02-18 | 1996-08-22 | Ego Elektro Blanc & Fischer | Overheating protection for electrical heating devices |
IT1391862B1 (en) | 2008-09-23 | 2012-01-27 | Indesit Co Spa | WASHING MACHINE, IN PARTICULAR A WASHING MACHINE, A WASHING MACHINE OR A DISHWASHER PROVIDED WITH A TEMPERATURE DETECTION DEVICE FOR THE ELECTRIC HEATING WARMING RESISTANCE OF THE WASHING LIQUID. |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE654037C (en) * | 1934-02-07 | 1937-12-08 | Voigt & Haeffner Akt Ges | Automatic temperature-dependent switch on electrically heated devices |
US2213722A (en) * | 1937-12-30 | 1940-09-03 | John E Smith | Electrical heating unit |
GB686800A (en) * | 1950-08-25 | 1953-01-28 | R E Thompson & Company Sunbury | Improvements in temperature-sensitive safety cut-outs for electric heaters |
GB704204A (en) * | 1950-12-07 | 1954-02-17 | Simpson Robert | An improved safety device for use with electrical appliances |
US2778917A (en) * | 1954-03-22 | 1957-01-22 | Sullivan Valve & Engineering Co | Electrical safety control apparatus |
GB8508051D0 (en) * | 1985-03-28 | 1985-05-01 | Otter Controlls Ltd | Heating elements |
-
1992
- 1992-07-14 IT ITTO920599A patent/IT1257915B/en active IP Right Grant
-
1993
- 1993-07-13 ES ES93111199T patent/ES2116370T3/en not_active Expired - Lifetime
- 1993-07-13 DE DE69318630T patent/DE69318630T2/en not_active Expired - Fee Related
- 1993-07-13 EP EP93111199A patent/EP0579170B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE69318630D1 (en) | 1998-06-25 |
IT1257915B (en) | 1996-02-16 |
ITTO920599A1 (en) | 1994-01-14 |
EP0579170A3 (en) | 1994-02-02 |
EP0579170A2 (en) | 1994-01-19 |
ITTO920599A0 (en) | 1992-07-14 |
DE69318630T2 (en) | 1998-09-10 |
ES2116370T3 (en) | 1998-07-16 |
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