Air conditioning pump shutoff

Claim 2

In an engine driven motor vehicle, apparatus for detecting an overheating condition in an air conditioning system having a fluid coolant and a pump for circulating the coolant comprising, in combination, a device defining a controlled current path and having a control mechanism therefor, application of a first voltage to the control mechanism causing the device to interrupt the current path and application of a second voltage to the control mechanism causing the device to complete the current path, a clutch coil connected in series with the controlled path and effective when energized to render the pump operable for circulating the coolant, means for connecting the device and the coil to a power source, a temperature responsive sensor having a first impedance when below a certain temperature and a second impedance when above the certain temperature positioned in the system so as to be immersed in the coolant when the coolant level in the system is greater than a certain level and not to be immersed in the coolant when the coolant level in the system is less than the certain level, circulation of the coolant when the sensor is immersed therein providing cooling of the sensor below the certain temperature, means responsive to the sensor impedance for applying a voltage to the control mechanism in response to the sensor impedance, said means applying the second voltage to the control mechanism when the sensor is of the first impedance and applying the first voltage to the control mechanism when the sensor is of the second impedance, and transient suppression means for dissipating energy stored in the coil when the said device interrupts the current path.

Claim 3

Low fluid detecting apparatus for detecting low levels of a pump circulated coolant in an air conditioning system of an engine driven motor vehicle comprising, in combination, a clutch coil this is effective when energized to render the pump operable for circulation of the coolant, a device defining a controlled current path and having a control mechanism therefor, the device being effective on application of a certain potential to the control mechanism to complete the current path and being effective on application of another potential to the control mechanism to interrupt said current path, means for connecting the coil in series circuit with said current path and a power source so as to effect energization of the coil by the power source only when said current path is completed by said device, engine responsive means responsive to operation of the vehicle engine for applying the certain potential to the control mechanism when the engine is in operation and for applying said other potential to the control mechanism when the engine is not in operation, a fluid level sensor responsive to the coolant level in the system for generating a first signal when the coolant level is above a certain level and a second signal when the coolant level is below the certain level, and time delay means responsive both to said engine responsive means and to said fluid level sensor generated signals for controlling the application of the certain potential to the control mechanism by the engine responsive means, the time delay means permitting the application of the certain potential to the control mechanism until the second signal has been generated by the fluid level sensor in a substantially uninterrupted manner for a predetermined time while the certain potential is applied to the control mechanism and thereafter precluding application of the certain potential to the control mechanism.

Claim 4

Low fluid detecting apparatus for detecting low levels of a pump circulated coolant in an air conditioning system of an engine driven motor vehicle comprising, in combination, a clutch coil this is effective when energized to render the pump operable for circulation of the coolant, a device defining a controlled current path and having a control mechanism therefor, the device being effective on application of a certain potential to the control mechanism to complete the current path and being effective on application of another potential to the control mechanism to interrupt said current path, means for connecting the coil in series circuit with said current path and a power source so as to effect energization of the coil by the power source only when said current path is completed by said device, engine responsive means responsive to operation of the vehicle engine for applying the certain potential to the control mechanism when the engine is in operation and for applying said other potential to the control mechanism when the engine is not in operation, a fluid level sensor responsive to the coolant level in the system for generating a first signal when the coolant level is above a certain level and a second signal when the coolant level is below the certain level, and time delay means responsive both to said engine responsive means and to said fluid level sensor generated signals for controlling the application of the certain potential to the control mechanism by the engine responsive means, the time delay means permitting the application of the certain potential to the control mechanism until the second signal has been generated by the fluid level sensor in a substantially uninterrupted manner for a predetermined time while the certain potential is applied to the control mechanism and thereafter precluding application of the certain potential to the control mechanism.

Claim 5

Apparatus for detecting low levels of a pump circulated coolant in a vehicle air conditioning system comprising, in combination, a clutch coil that is effective when energized to render the pump operable and effective when deenergized to preclude operation of the pump; means defining a controlled current path in series with the coil, said means having a control mechanism and being effective on application of a certain potential to the control mechanism to complete the current path and on application of another potential to the control mechanism to interrupt the current path; means for connecting a power source in series with the current path effective to energize the coil when the current path is complete and to deenergize the coil when the current path is interrupted; means responsive to operation of the engine for applying a certain potential to the control mechanism when the engine is in operation and for applying said other potential to the control mechanism when the engine is not in operation, thereby precluding energization of the coil unless the engine is in operation; a current responsive device connecting said engine responsive means to the control mechanism, said current responsive device being characterized as having a very low impedance until the current therethrough has exceeded a certain current level for a substantially uninterrupted predetermined time and thereafter having a very high impedance, current drawn by the control mechanism through the current responsive device being below the certain current level; coolant responsive means for generating a first signal when the coolant level is above a certain level and a second signal when the coolant level is below a certain level; and means responsive to the signals generated by the coolant level responsive means for drawing additional current through the current responsive device when the second signal is generated whereby the combined currents drawn through the current responsive device by the control mechanism and said last recited means exceed the certain current level so as to effect a change of the current responsive device impedance from a low to a high value, thereby preventing application of the certain potential to the control mechanism so as to prevent energization of the coil and operation of the pump when the coolant level has remained below the certain level for the predetermined time.

Claim 6

Apparatus for detecting low levels of a pump circulated coolant in a vehicle air conditioning system comprising, in combination, a clutch coil that is effective when energized to render the pump operable and effective when deenergized to preclude operation of the pump; means defining a controlled current path in series with the coil, said means having a control mechanism and being effective on application of a certain potential to the control mechanism to complete the current path and on application of another potential to the control mechanism to interrupt the current path; means for connecting a power source in series with the current path effective to energize the coil when the current path is complete and to deenergize the coil when the current path is interrupted; means responsive to operation of the engine for applying a certain potential to the control mechanism when the engine is in operation and for applying said other potential to the control mechanism when the engine is not in operation, thereby precluding energization of the coil unless the engine is in operation; a current responsive device connecting said engine responsive means to the control mechanism, said current responsive device being characterized as having a very low impedance until the current therethrough has exceeded a certain current level for a substantially uninterrupted predetermined time and thereafter having a very high impedance, current drawn by the control mechanism through the current responsive device being below the certain current level; coolant responsive means for generating a first signal when the coolant level is above a certain level and a second signal when the coolant level is below a certain level; and means responsive to the signals generated by the coolant level responsive means for drawing additional current through the current responsive device when the second signal is generated whereby the combined currents drawn through the current responsive device by the control mechanism and said last recited means exceed the certain current level so as to effect a change of the current responsive device impedance from a low to a high value, thereby preventing application of the certain potential to the control mechanism so as to prevent energization of the coil and operation of the pump when the coolant level has remained below the certain level for the predetermined time.