Water temperature sensing and control means for automatic washer

• US 4,643,350 A
• Filed: 12/17/1985
• Issued: 02/17/1987
• Est. Priority Date: 12/17/1985
• Status: Expired due to Term

• Current Assignee: Whirlpool Corporation
• Original Assignee: Whirlpool Corporation
• Inventors: Reniger, Bruce L., DeSchaaf, Clifford L.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US06/809,725
• Time in Patent Office: 427 Days
• Field of Search: 236/12.12, 236/12.1, 236/12.11, 236/DIG. 12, 62/158, 364/502, 8/158, 68/12.3, 374/147, 374/102, 4/192-194
• US Class Current: 236/12.12
• CPC Class Codes: D06F 2103/16 Washing liquid temperature
• CPC Class Codes: D06F 34/24 Liquid temperature
• CPC Class Codes: G05D 23/1393 characterised by the use of electric means

Abstract

A water temperature sensing and control apparatus for automatic washers having a thermistor mounted within a projection that extends into a water inlet stream in a water inlet housing. A thermally semiconductive potting material encases the thermistor to provide a delayed response of the sensor to changes in water inlet temperature. A control circuit connected to the thermistor includes a pair of comparators for controlling hot and cold water inlet valves in response to the sensed temperature to achieve one of a plurality of selectable wash bath temperatures.

Claims

1. In an automatic washer having means for containing a wash bath, hot and cold inlet valves connected to respective sources of hot and cold water, and means for delivering a combined flow of water from said valves to said wash bath, improved means for controlling the temperature of water delivered to said wash bath comprising:

a temperature sensor mounted to sense the temperature of said combined flow of water to said wash bath;

means forming a thermally semiconductive layer between said temperature sensor and said combined flow to provide a predetermined delayed response of said sensor to temperature changes of said combined flow;

temperature control means for establishing a desired water bath temperature;

a valve control circuit connected to control said inlet valves, said circuit being connected to said sensor and said temperature control means and being responsive to signals therefrom to operate said valves such that an average temperature of said flow of water to said wash bath is substantially equal to said desired water bath temperature;

means in said valve control circuit for providing a time delay, said time delay being shorter than said sensor delayed response.

2. An improved control means as claimed in claim 1, wherein said circuit time delay means includes feedback means to prevent oscillations of the circuit and establish a minimum cycle time for operating the valves activated by the valve circuit.

3. In an automatic washer having means for containing a wash bath, hot and cold inlet valves connected to respective sources of hot and cold water, and means for delivering a combined flow of water from said valves to said wash bath, improved means for controlling the temperature of water delivered to said wash bath comprising:

a temperature sensor mounted to sense the temperature of said combined flow of water to said wash bath;

means forming a thermally semiconductive layer between said temperature sensor and said combined flow to provide a predetermined delayed response of said sensor to temperature changes of said combined flow;

temperature control means for establishing a desired water bath temperature;

a valve control circuit connected to control said inlet valves, said circuit being connected to said sensor and said temperature control means and being responsive to signals therefrom to operate said valves such that an average temperature of said flow of water to said wash bath is substantially equal to said desired water bath temperature;

a projection extending from said delivering means into said combined flow of water, said temperature sensor being disposed within said projection and having said thermally semiconductive means disposed between said sensor and said combined flow to provide time delay in the thermal response of the temperature sensor;

wherein said projection is a trough extending transversely of said combined flow, thereby to provide a thin wall relative to the housing.

4. In an automatic washer having means for containing a wash bath, hot and cold inlet valves connected to respective sources of hot and cold water, and means for delivering a combined flow of water from said valves to said wash bath, improved means for controlling the temperature of water delivered to said wash bath comprising:

a temperature sensor mounted to sense the temperature of said combined flow of water to said wash bath;

means forming a thermally semiconductive layer between said temperature sensor and said combined flow to provide a predetermined delayed response of said sensor to temperature changes of said combined flow;

temperature control menas for establishing a desired water bath temperature;

a valve control circuit connected to control said inlet valves, said circuit being connected to said sensor and said temperature control means and being responsive to signals therefrom to operate said valves such that an average temperature of said flow of water to said wash bath is substantially equal to said desired water bath temperature;

wherein said valve control circuit includes a window comparator arrangement to provide hysteresis in said valve control circuit.

5. In an automatic washer having means for containing a wash bath, a water temperature sensing assembly comprising:

a water inlet housing defining a water flow path to said wash bath;

a temperature sensor;

a hollow projection extending into said water flow path, said sensor being mounted within said hollow projection;

thermally semiconductive potting material within said projection, said sensor being embedded in said potting material to provide a predetermined thermal time delay between changes in the temperature of said water flow and the response of said sensor; and

means for providing electrical contact with said sensor extending through said potting material;

wherein said hollow projection is trough shaped to form a relatively thin wall which extends transversely of the direction of said water flow path.

6. In an automatic washer having means for containing a wash bath, hot and cold inlet valves connected to respective sources of hot and cold water, means for selecting one of a plurality of wash temperature modes, and an inlet housing for delivering a combined flow of water from said valves to said wash bath, improved means for controlling the temperature of water delivered to said wash bath comprising:

a hollow projection formed in said inlet housing and extending into said combined flow;

a temperature sensor mounted within said hollow projection;

potting material in said hollow projection forming a thermally semiconductive layer between said sensor and said projection; and

,

a valve control circuit connected to said sensor, including biasing means in said circuit connected to said wash mode selecting means for selectively biasing said sensor, a window comparator arrangement connected to said sensor, and valve switching means connected to outputs of said window comparator arrangement.

7. An improved control means as claimed in claim 6, wherein said window comparator arrangement includes a voltage divider network and first and second comparators connected to respective first and second intermediate locations on said voltage divider network to provide first and second reference levels.

8. An improved control means as claimed in claim 7, further comprising first and second feedback resistors connected to said respective first and second comparators to prevent oscillation of the output signals from the respective comparators and thus provide a delay supplementing the delay of the sensor.

9. An improved control means as claimed in claim 6, further comprising:

at least one buffer connected between said sensor and said window comparator arrangement to isolate changes in impedance caused by switching.

10. An improved control means as claimed in claim 6, further comprising:

power conditioning means in said valve control circuit to provide power thereto.