WO1991019311A1 - Ameliorations apportees au reglage de temperature - Google Patents

Ameliorations apportees au reglage de temperature Download PDF

Info

Publication number
WO1991019311A1
WO1991019311A1 PCT/GB1991/000926 GB9100926W WO9119311A1 WO 1991019311 A1 WO1991019311 A1 WO 1991019311A1 GB 9100926 W GB9100926 W GB 9100926W WO 9119311 A1 WO9119311 A1 WO 9119311A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
heating
volume
actuating element
thermally
Prior art date
Application number
PCT/GB1991/000926
Other languages
English (en)
Inventor
Robert Andrew O'neill
Thomas Wise
Original Assignee
Otter Controls Limited
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
Application filed by Otter Controls Limited filed Critical Otter Controls Limited
Publication of WO1991019311A1 publication Critical patent/WO1991019311A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/12—Means for adjustment of "on" or "off" operating temperature
    • H01H37/14—Means for adjustment of "on" or "off" operating temperature by anticipatory electric heater
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H2037/5463—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting the bimetallic snap element forming part of switched circuit
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H2037/5472—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting having an omega form, e.g. the bimetallic snap element having a ring shape with a central tongue

Definitions

  • This invention generally concerns improvements relating to temperature control, and more particularly though not exclusively concerns the control of storage type immersion heaters as for example in hot water tanks.
  • thermostats for the control of the temperature of water within a storage tank have typically hitherto been of two main types, namely:
  • a bimetal based device wherein a stressed bimetal form is constrained to change shape at a predetermined temperature and this shape change is arranged to operate the contacts of a switching means.
  • the temperature at which the operating means functions may be arranged to be adjusted in order to allow the temperature of the stored water to be varied, for example to allow use in areas of high water hardness where a lower setting is desirable to prevent excessive scaling of the heating element.
  • the temperature at which the stored water is controlled is determined by the temperature at which the contacts of the switching means are arranged to open, and that a swing in the temperature of the water is necessary to cause said contacts to reclose and maintain the water at or close to a desired temperature. This swing may be undesirable and there are a number of known means available to reduce it such as, for example, positioning a heater close to the temperature sensing element so that the heater causes the opening of the contacts at a lower water temperature than would otherwise be the case.
  • the heater is then switched off (possibly by the same contacts), so that the contacts will reclose at the same water temperature as if the heater were not provided.
  • the swing in water temperature is reduced, since the high temperature (switch off) is reduced while the low temperature (switch on) remains unchanged.
  • the present invention proposes to make use of this heating effect to almost completely eliminate any swing in the temperature of the stored water. It is a feature of this invention that the temperature of the stored water will be determined by the switch on (low) temperature of the controlling device substantially independently of its switch off (high) temperature. It is a further feature of this invention that the temperature of the stored water will approach its final value at a progressively reducing rate, thus eliminating the overshooting of the desired temperature associated with conventional controls of the first type mentioned above which control at their switch off (high) temperature. This second effect is similar to proportional control, common in more sophisticated temperature controllers.
  • a system comprising means for storing a volume of liquid, electrically powered heating means for heating said liquid, and thermostatic control means associated with said heating means for enabling the temperature of the stored liquid to be determined, and wherein the thermostatic control means includes a thermally- responsive switch-actuating element arranged to be subjected to heating by the flow therethrough of electrical current for powering said heating means, the said thermally-responsive switch-actuating element is arranged in heat transfer relationship with the volume of liquid to be heated but not directly subject to the temperature thereof, and the said thermally- responsive switch-actuating element being formed so as to be rapidly heated through its ON (low) to OFF (high) temperature differential range by the flow therethrough of the heating means power current whereby the temperature of the volume of liquid will in operation of the system stabilize around the ON (low) temperature end of the said differential range.
  • the invention also extends to a thermostatic control device for use in a system as above-described and wherein the device includes a thermally-responsive switch-actuating element (e.g. a bimetal) formed to develop significant electrical (I ⁇ Rt) heating when subjected to a predetermined current flow therethrough commensurate with the current loading of the heating means and wherein the switching differential of the switch-actuating element is such as to be readily exceeded by the temperature rise caused by said electrical heating.
  • a thermally-responsive switch-actuating element e.g. a bimetal
  • a bimetallic switch might be accommodated in an air space within a cover enclosing the power supply terminals provided in a head portion of an immersion heater associated with a water storage cylinder.
  • the bimetallic switch will thus be subject to the temperature of the air in such air space, rather than to the temperature of the water in the storage cylinder, but nonetheless will be in heat transfer relationship, via the air in the air space, with the water.
  • the current to the immersion heating element flows through the bimetallic element of the switch thereby causing self- heating thereof until such time as the bimetal reaches its switching temperature and the switch switches off; in this time period a certain amount of heat will be injected into the water in the storage cylinder and the water temperature will rise.
  • the bimetal temperature will now begin to fall, given that the bimetal is in a relatively cool air space.
  • the bimetal will cause the switch to switch on again and the cycle will be repeated with yet a further pulse of heat being injected into the water. This cyclical process will be repeated as the water temperature rises towards the low (switch-on) temperature of the bimetal.
  • Figure 1 shows the outline shape of an exemplary bimetal element
  • Figures 2 and 3 are plan and side elevation views, respectively, of an exemplary switching device incorporating a bimetal element as in Figure 1;
  • Figure 4 is a graphical representation of the function of the device to be described. Detailed Description of the Embodiment
  • FIGS 1, 2 and 3 show a thermal cut-out comprising a rectangular sheet of bimetal 1, attached by welding to a brass mounting plate 2, to which electrical connection may be made at terminal 3.
  • a U-shaped cut-out 4 defining a central limb 5 on which is secured a silver faced contact 6.
  • a further brass plate 7 is disposed such that a similar contact 8 mounted on it is in alignment with the first mentioned contact 6.
  • the first and second brass plates 2 and 7 are mounted with appropriate spacing from each other by means of an insulating switch body component 10, and the brass plate 7 has a terminal 9 to allow a second electrical connection to be made to it.
  • the rectangular sheet of bimetal 1 is deformed into a generally spherical dished surface, with the high expansion component being on the concave side 11, such that the central limb 5 is forced out of the plane of the sheet and the contact 6 is forced into firm contact with the contact 8.
  • the water temperature will start to rise, as will the temperature of the bimetal.
  • the bimetal temperature will exceed that of the water by approximately 30°C as indicated by reference 16.
  • the bimetal temperature will be at around 90°C as indicated by reference 17 which is its switch off temperature.
  • the device will therefore switch off the supply to the heater, and the water and the device will start to cool.
  • the device is in thermal contact with the air space in the heating element head which is cooled by the still cool water, it will rapidly cool to below 70°C as indicated by reference 18 and will switch on before the water has cooled by a significant amount as indicated by reference 19.
  • the bimetal will once more have reached its switch off point as indicated by reference 20, the water will have heated by some amount as indicated by reference 21, and the cycle will be repeated. This cycling will continue until the water reaches 70°C as indicated by reference 22, at which point the device will not switch on until the water itself has cooled to slightly below 70°C. When the device switches on, the water will be heated to slightly above 70°C whereupon the device will switch off and will remain switched off until the water cools again. Thus the water will be maintained at a temperature very close to the switch on value of the device, which will only cycle sufficiently to maintain this temperature.
  • the switch on temperature of the device may be adjusted by adjusting the position of the stop 12. This will have the effect of also varying the differential, but provided the above conditions are met control will be achieved and only the cycle rate will vary. It should be noted that varying degrees of sensitivity to current can be achieved by using bimetals of differing electrical resistivity whilst keeping the form of the device otherwise constant. Thus a range of devices may be constructed, suitable for the control of loads of differing power.
  • thermostatic switching device having a differential less than the temperature rise caused by the passage of the current being controlled, and the use of such a device to control the temperature of any substance within close limits of the switch on temperature of the device.
  • the invention has been particularly described in the foregoing with reference to electrically-heated hot water storage and supply systems, it is to be appreciated that the invention is not restricted to such an application.
  • the invention could be used with a hot water jug as a simmer control, in which case a bimetallic or other thermostatic switch sensitive to load current flow to be heated thereby might for example be secured to the body of a plastics water heating container.
  • a bimetallic or other thermostatic switch sensitive to load current flow to be heated thereby might for example be secured to the body of a plastics water heating container.
  • the application could be for the heating of non-liquid matter, such as for example the bulk of an automotive vehicle seat.

Abstract

Un thermoplongeur électrique possède un élément, une tête, un couvercle définissant un vide d'air avec ladite tête, ainsi qu'un commutateur à thermostat monté à l'intérieur du vide d'air et sensible à la température de celui-ci, le commutateur subissant également un autoéchauffement sous l'effet du flux de courant de haute intensité en direction du thermoplongeur, et apte à commuter rapidement de son état de MARCHE (faible température) à son état d'ARRET (température élevée) lors d'un tel autoéchauffement. Lorsqu'il est installé dans un ballon d'eau chaude ménager, le commutateur á thermostat fait l'aller et le retour à plusieurs reprises entre les états de MARCHE et d'ARRET afin d'amener la température de l'eau progressivement au niveau de celle de l'état de MARCHE (faible température) du thermostat, et maintient la température de l'eau à peu près à ce niveau. Le thermoplongeur peut également servir à réguler l'ébullition à petit feu dans les bouilloires, à chauffer les sièges de véhicules automobiles, ou analogue, et représente une alternative efficace aux dispositifs bien plus complexes de réglage de température.
PCT/GB1991/000926 1990-06-07 1991-06-07 Ameliorations apportees au reglage de temperature WO1991019311A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB909012715A GB9012715D0 (en) 1990-06-07 1990-06-07 Improvements relating to temperature control
GB9012715.0 1990-06-07

Publications (1)

Publication Number Publication Date
WO1991019311A1 true WO1991019311A1 (fr) 1991-12-12

Family

ID=10677226

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1991/000926 WO1991019311A1 (fr) 1990-06-07 1991-06-07 Ameliorations apportees au reglage de temperature

Country Status (4)

Country Link
EP (1) EP0532620A1 (fr)
AU (1) AU7975891A (fr)
GB (2) GB9012715D0 (fr)
WO (1) WO1991019311A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1835372A1 (fr) * 2006-03-17 2007-09-19 S.A.T.E. Dispositif de régulation thermostatique de chauffe-eau électrique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR992256A (fr) * 1944-06-06 1951-10-16 Calor Sa Perfectionnement au montage des dispositifs thermostatiques aux bouilloires électriques et appareils similaires
US3386066A (en) * 1965-10-24 1968-05-28 Texas Instruments Inc Switch having simplified structural features
US3431527A (en) * 1966-12-30 1969-03-04 Texas Instruments Inc Thermostatic snap-acting switch

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1052637A (fr) *
GB683289A (en) * 1949-11-03 1952-11-26 Merlin Mouldings Ltd Improvements in or relating to electric thermostats
GB761268A (en) * 1954-03-19 1956-11-14 Sunbeam Corp Electrically heated coffee percolator
GB1598552A (en) * 1977-03-18 1981-09-23 Liquifry Co Ltd Electrical heater
DE3219517C2 (de) * 1982-05-25 1986-09-25 Thermostat- und Schaltgerätebau GmbH & Co KG, 8730 Bad Kissingen Temperaturreglerschalter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR992256A (fr) * 1944-06-06 1951-10-16 Calor Sa Perfectionnement au montage des dispositifs thermostatiques aux bouilloires électriques et appareils similaires
US3386066A (en) * 1965-10-24 1968-05-28 Texas Instruments Inc Switch having simplified structural features
US3431527A (en) * 1966-12-30 1969-03-04 Texas Instruments Inc Thermostatic snap-acting switch

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1835372A1 (fr) * 2006-03-17 2007-09-19 S.A.T.E. Dispositif de régulation thermostatique de chauffe-eau électrique
FR2898700A1 (fr) * 2006-03-17 2007-09-21 Applic Thermiques Europ Soc D "dispositif de regulation thermostatique de chauffe-eau electrique"

Also Published As

Publication number Publication date
GB9112276D0 (en) 1991-07-24
GB2248144A (en) 1992-03-25
EP0532620A1 (fr) 1993-03-24
AU7975891A (en) 1991-12-31
GB9012715D0 (en) 1990-08-01

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