SPA control circuit

• US 5,585,025 A
• Filed: 09/13/1993
• Issued: 12/17/1996
• Est. Priority Date: 09/13/1993
• Status: Expired due to Fees

• Current Assignee: Softub, Inc.
• Original Assignee: Softub, Inc.
• Inventors: Idland, Carsten H.
• Primary Examiner(s): Paschall, Mark H.
• Application Number:
  US08/118,763
• Time in Patent Office: 1,191 Days
• Field of Search: 219/491, 219/519, 219/492, 219/497, 219/501, 219/506, 219/485, 219/481, 219/505, 307/117, 307/119, 4/541.1, 4/545, 4/584, 4/541.2, 361/2, 361/15
• US Class Current: 219/497
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: G05D 23/20 with sensing elements having variation of electric or magnetic properties with change of temperature G05D23/13 takes precedence

Abstract

A spa control circuit is provided for regulating a water circulation and heating system in a spa or hot tub or the like. The control circuit comprises a thermostat circuit and a high temperature limit circuit, both of which receive a temperature signal from a common temperature sensor. A safety circuit responds to sensor failure to prevent operation of the circulation/heating system. A latching relay ensures system reset in the same operational state following a power outage. An arc suppression circuit substantially prevents arc damage to relay contacts subjected to frequent opening and closing in response to on-off cycling of the thermostat circuit. In a preferred form, the control circuit components are mounted within a compact housing having a heat transfer member in heat exchange relation with circulating spa water, whereby the spa water is used to prevent overheating of the control circuit components.

Claims

1. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

temperature sensor means responsive to the temperature of the water for generating a temperature signal representing water temperature;

switch means movable between opened and closed positions for de-energizing and energizing the heater means; and

circuit means responsive to said temperature signal for moving said switch means between the opened and closed positions to prevent overheating of the water;

said circuit means including means for detecting failure of said temperature sensor means and for responding thereto to move said switch means to de-energize said heater means;

said switch means comprising a high temperature limit relay, and wherein said circuit means comprises a high temperature limit circuit responsive to said temperature signal for moving said high temperature limit relay to de-energize the heater means when the water temperature reaches a predetermined upper limit;

said switch means further comprising a thermostat relay, said circuit means having a thermostat circuit responsive to said temperature signal for moving said thermostat relay between opened and closed positions to respectively energize and de-energize the heater means to maintain the water temperature within the limits of a normal operating range less than said predetermined upper limit;

said temperature sensor means comprising a single temperature sensor for generating said temperature signal coupled to both of said high temperature limit and thermostat circuits;

said circuit means including manual reset means for moving said switch means to energize the heater means, said circuit means including temperature responsive mean and said means for detecting sensor failure for independently moving said switch means to de-energize the heater mean;

said circuit means further including a latching relay coupled to said switch means, said latching relay having a switch arm movable between a power-on position for moving said switch means to energize the heater means and a power-off position for moving said switch means to de-energize the heater means, said temperature responsive means and said means for detecting sensor failure being connected to said latching relay to move said switch arm to the power-off position respectively in response to the water temperature reaching said predetermined upper limit and in response to sensor failure, said manual reset means being connected to said latching relay to move said switch arm to the power-on position.

2. The control circuit of claim 1 wherein said circuit means further includes a timer circuit having a manually settable timer switch and means responsive to operation of said timer switch for moving said thermostat relay to the closed position for a selected time period irrespective of said thermostat circuit.

3. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

temperature sensor means responsive to the temperature of the water for generating a temperature signal representing water temperature;

switch means movable between opened and closed positions for de-energizing and energizing the heater means; and

circuit means responsive to said temperature signal for moving said switch means between the opened and closed positions to prevent overheating of the water;

said circuit means including means for detecting failure of said temperature sensor means and for responding thereto to move said switch means to de-energize said heater means;

said switch means comprising a high temperature limit relay, and wherein said circuit means comprises a high temperature limit circuit responsive to said temperature signal for moving said high temperature limit relay to de-energize the heater means when the water temperature reaches a predetermined upper limit;

said switch means further comprising a thermostat relay, said circuit means having a thermostat circuit responsive to said temperature signal for moving said thermostat relay between opened and closed positions to respectively energize and de-energize the heater means to maintain the water temperature within the limits of a normal operating range less than said predetermined upper limit;

said temperature sensor means comprising a single temperature sensor for generating said temperature signal coupled to both of said high temperature limit and thermostat circuits;

said thermostat relay including a pair of contacts, and further including an arc suppression circuit for substantially preventing arc formation across said thermostat relay contacts in response to movement of said thermostat relay between the opened and closed positions, said arc suppression circuit comprising a capacitor and a transient voltage suppressor connected across said contacts in parallel relation with each other.

4. The control circuit of claim 3 wherein said arc suppression circuit further comprises a resistor connected across said contacts in series with said capacitor, said transient voltage suppressor being connected across said contacts in parallel with said capacitor and resistor.

5. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

temperature sensor means responsive to the temperature of the water for generating a temperature signal representing water temperature;

switch means movable between opened and closed positions for de-energizing and energizing the heater means;

circuit means responsive to said temperature signal for moving said switch means between the opened and closed positions to prevent overheating of the water;

said circuit means including means for detecting failure of said temperature sensor means and for responding thereto to move said switch means to de-energize said heater means;

said switch means comprising a high temperature limit relay, and wherein said circuit means comprises a high temperature limit circuit responsive to said temperature signal for moving said high temperature limit relay to de-energize the heater means when the water temperature reaches a predetermined upper limit;

said switch means further comprising a thermostat relay, said circuit means having a thermostat circuit responsive to said temperature signal for moving said thermostat relay between opened and closed positions to respectively energize and de-energize the heater means to maintain the water temperature within the limits of a normal operating range less than said predetermined upper limit;

said temperature sensor means comprising a single temperature sensor for generating said temperature signal coupled to both of said high temperature limit and thermostat circuits; and

a housing having the components of the control circuit mounted therein, said housing including a heat transfer member in heat exchange relation with the water, whereby the components of the control circuit are cooled by the water and whereby heat generated by the components of the control circuit supplements the heater means to heat the water.

6. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

a temperature sensor responsive to the water temperature to generate a temperature signal;

a thermostat relay and a high temperature limit relay connected in series between a power supply and the heater means, each of said relays being movable between opened and closed positions for energizing the heater means when both of said relays are in the closed positions and for de-energizing the heater means when one of said relays is in the opened position;

a thermostat circuit responsive to said temperature signal for moving said thermostat relay between the opened and closed positions to regulate water temperature with the limits of a selected normal range of operation;

a high temperature limit circuit responsive to said temperature signal for moving said high temperature limit relay between the opened and closed positions to de-energize the heater means when the water temperature reaches a predetermined upper limit higher than said normal range;

a safety circuit including means for detecting failure of said temperature sensor and for responding thereto to move at least one of said relay to the opened position to de-energize the heater means;

manual reset means for moving said high temperature limit relay to the closed position; and

a latching relay having a switch arm movable between a power-on position and a power-off position for respectively moving said high temperature limit relay between said closed and opened positions, said high temperature limit circuit and said safety circuit being connected to said latching relay to independently move said switch arm to the power-off position respectively in response to the water temperature reaching said predetermined upper limit and in response to sensor failure, said manual reset means being connected to said latching to move said switch arm to the power-on position.

7. The control circuit of claim 6 wherein said safety circuit responds to failure of the sensor to move said high temperature limit relay to the opened position.

8. The control circuit of claim 6 wherein said thermostat relay includes a pair of contacts, and further including an arc suppression circuit for substantially preventing arc formation across said thermostat relay contacts in response to movement of said thermostat relay between the opened and closed positions.

9. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

a temperature sensor responsive to the water temperature to generate a temperature signal;

a thermostat relay and a high temperature limit relay connected in series between a power supply and the heater means, each of said relays being movable between opened and closed positions for energizing the heater means when both of said relays are in the closed positions and for de-energizing the heater means when one of said relay in the opened position;

a thermostat circuit responsive to said temperature signal for moving said thermostat relay between the opened and closed positions to regulate water temperature with the limits of a selected normal range operation;

a high temperature limit circuit responsive to said temperature signal for moving said high temperature limit relay between the opened and closed positions to de-energize the heater means when the water temperature reaches a predetermined upper limit higher than said normal range;

a safety circuit including means for detecting failure of said temperature sensor and for responding thereto to move at least one of said relay to the opened position to de-energize the heater means; and

a housing having the components of the control circuit mounted therein, said housing including a heat transfer member in heat exchange relation with the water, whereby the components of the control circuit are cooled by the water and whereby heat generated by the components of the control circuit supplements the heater means to heat the water.

10. A control circuit for a spa having a tub for receiving a supply of water and heater means energizable for heating the water, said control circuit comprising:

a temperature sensor responsive to the water temperature to generate a temperature signal;

a thermostat relay including a pair of contacts and being connected between a power supply and the heater means, said relay being movable between closed and opened positions for respectively energizing and de-energizing the heater means;

a thermostat circuit responsive to said temperature signal for moving said thermostat relay between the opened and closed positions to regulate water temperature with the limits of a selected normal range of operation; and

an arc suppression circuit for substantially preventing arc formation across said thermostat relay contacts in response to movement of said thermostat relay between the opened and closed position;

said arc suppression circuit comprising a capacitor and resistor connected in series across said contacts, and a transient voltage suppressor connected across said contacts in parallel with said capacitor and resistor.

11. A control circuit for a spa having a tub for receiving a supply of water, heater means energizable for heating the water, and circulation means for circulating the water to said heating means, said control circuit comprising:

temperature sensor means responsive to the temperature of the water for generating a temperature signal representing water temperature;

switch means movable between opened and closed positions for de-energizing and energizing the heater means; and

circuit means responsive to said temperature signal for moving said switch means between the opened and closed positions to regulate the temperature of the water; and

a housing having the components of the control circuit mounted therein, said housing including a heat transfer member in heat exchange relation with the water circulated to the heater means, whereby the components of the control circuit are cooled by the water and whereby heat generated by the components of the control circuit supplements the heater means to heat the water.

12. An arc suppression circuit for substantially preventing arc formation across a relay having a pair of contacts and switch means for opening and closing said contacts, said arc suppression circuit comprising:

a capacitor and a resistor connected across said contacts in series relation; and

a transient voltage suppressor connected across said contacts in parallel with said capacitor and resistor.