GB742585A - Improvements in and relating to thermally controlled valves - Google Patents

Abstract

742,585. Washing-machines. ENGLISH ELECTRIC CO., Ltd. Sept. 18, 1953 [Sept. 19, 1952], No. 23565/52. Class 138 (2). In a thermally-controlled valve system having thermostatic means to control the temperature Tm of a mixture of fluids obtained from two sources of different temperatures Th and Tc, the flow of at least one of the fluids to the mixture is controlled by valve means governed by the thermostatic means which is disposed in or near a path of fluid flow so as to be subjected alternately to one and then the other of a particular two of the temperatures Tm, Th and Tc, the two temperatures to which the thermostatic means is subjected differing by an amount greater than the temperature differential of the thermostatic means. The invention enables the temperature of the mixed fluid to be controlled within finer limits than the normal temperature differential of the thermostat. Several examples are described, viz. (i) hot and cold fluid supplied alternately under thermostatic control ; (ii) cold fluid supplied continuously with intermittent hot flow under thermostatic control ; (iii) hot and cold fluids supplied alternately, the hot being thermostatically controlled and the cold being for a fixed period ; (iv) alternate flow of hot and cold fluid under timer control the flow of either being interrupted when the thermostat is hot or cold enough. In these examples the rates of flow of fluid are regarded as constant, while in a modification of example (iv), for use where the supply pressure varies, the thermostat permits fixed quantities to flow. Example (i).-Fig. 1 (Prov.) shows a plan view of a valve system for a washing machine. Cold water is supplied by a valve 1 under the control of a solenoid armature 5, through a port 7 and passage 8 to a discharge port 9 located over the clothes in a receptacle 14. Hot water is supplied by a similar valve 3 to a port 9 discharging between the receptacle 14 and an outer tub 15. Baffles 10 enable the water to be in contact with the sole (not shown) of a contact type thermostat only during the flow of the water (see Fig. 2 of Provisional, not shown). For optimum results the rates of flow of cold and hot liquids should be equal and this may be achieved by using a suitably sized orifice on the cold liquid supply port to allow for differences in the pressure of the hot and cold supplies. Example (ii).-Fig. 1 (Comp.) shows a washing receptacle 17 rotatable within a tub 18, a valve system 19 admitting cold water at a steady rate through a tube 20. Hot water is admitted intermittently through a tube 21 having a thermostat 22 near its outlet. The thermostat responds to the temperature of the hot water when the latter is flowing and to the temperature of the mixture when the hot water is not flowing, The temperature of the hot water must be appreciably greater than the required temperature of the mixture for the thermostatic control to function well. The temperature of the mixture may be adjusted by altering the size of orifice in the cold or hot supply. Example (iii).-The timer of an automatic washing machine may be used to control the time for which the cold water flows, the thermostat controlling the flow of hot water. Example (iv).-In Fig. 3 hot water flows through a valve 25 and cold water through a valve 26 when coils 27 and 28 respectively are energized. A two-way switch 29 is changed over at regular intervals by a timer mechanism and a switch 30 is controlled by a thermostat 31. When hot water is flowing and causes the thermostat to attain its higher operating temperature, switch 30 is changed and no water flows until switch 29 changes, when cold water flows. Modifications.-Each supply line may include a spring-biased piston 33, Fig. 4, in a cylinder 35. When a valve 32 is opened a fixed quantity of liquid is ejected through the valve. When the valve 32 is reclosed the spring 34 returns the piston to the original position shown due to a small clearance between the piston and cylinder. This arrangement may be substituted for valves 25 and/or 26 in Fig. 3. The invention also covers a system subjected alternately to Tc and Tm instead of to Th and Tm, or Th and Tc.