US 2014/0360211 A1 · Controlling HVAC Condenser Fans Using Pressure Sensors

Abstract

A heating, ventilation and air conditioning (HVAC) unit may both save energy and monitor for fault conditions by monitoring an ambient air temperature, compressor discharge pressure, and evaporator suction pressure and using these measurements to identify known conditions. Compressor discharge pressure and ambient temperature may be used as indices to a look up table or map to determine a speed and direction for a condenser fan. In some cases, the look up table may direct the fan to be reversed at full power in an attempt to remove a suspected buildup of dirt or debris at the condenser. Ambient temperature and evaporator suction pressure may be monitored for a combination of conditions that indicate low refrigerant levels, allowing the compressor to be turned off before damage to the compressor is sustained.

Claims20

Dependent claims

A method of operating a heat, ventilation, and air conditioning (HVAC) unit operated in an earthmoving machine, the method comprising:

sensing a compressor output pressure;
sensing a compressor input pressure;
during a time period when the compressor output pressure is in an operating pressure range, controlling a speed of a condenser fan responsive to the compressor output pressure;
and
operating the condenser fan in a reverse direction responsive to the compressor output pressure being above the operating pressure range.

2 more elements

A controller for use in heat, ventilation, and air conditioning (HVAC) equipment operated in an earthmoving machine, the controller comprising:

a compressor control signal output operatively coupled to a compressor of the HVAC equipment;
a condenser fan control signal output operatively coupled to a condenser fan of the HVAC equipment;
a first pressure sensor input that receives an output pressure of the compressor;
a second pressure sensor input that receives a suction pressure between an evaporator of the HVAC equipment and the compressor;
a temperature input that receives an ambient air temperature;
a processor coupled to the compressor control signal output, the condenser fan control signal output, the first pressure sensor input, the second pressure sensor input, and the temperature input;
and
a computer-readable memory that stores i) operating characteristics including condenser fan control data and ii) instructions that when executed by the processor cause the controller to:
turn on the compressor via the compressor control signal output based on a request for air conditioning and an ambient temperature being above a first threshold temperature;
select a condenser fan speed from the condenser fan control data responsive to the ambient air temperature and the output pressure of the compressor;
and
set the condenser fan speed to the selected condenser fan speed via the condenser fan control signal.

9 more elements

A heat, ventilation, and air conditioning (HVAC) unit operated in an earthmoving machine, the HVAC unit comprising:

a compressor that is selectively operable, responsive to a compressor control signal;
a condenser fluidly coupled to the compressor;
an expansion valve fluidly coupled to the condenser;
an evaporator fluidly coupled to the expansion valve and the compressor;
a first pressure sensor that measures an output pressure of the compressor;
a second pressure sensor that measures a suction pressure between the expansion valve and the compressor;
an ambient temperature sensor;
a condenser fan that provides cooling to the condenser, the condenser fan having variable speed and reversible direction responsive to a condenser fan control signal;
and
a controller electrically coupled to the first pressure sensor, the second pressure sensor, the ambient temperature sensor, and the fan, the controller configured to:
i) provide the compressor control signal to selectively operate the compressor, and ii) provide the fan control signal, the controller including:
a processor;
a compressor control signal output;
a condenser fan control signal output;
a first pressure sensor input coupled to the first pressure sensor;
a second pressure sensor input coupled to the second pressure sensor;
an ambient temperature input coupled to the ambient temperature sensor;
a computer-readable memory that stores instructions that when executed by the processor cause the controller to:
turn on the compressor via the compressor control signal output based on a request for air conditioning;
select a condenser fan speed from condenser fan control data stored in the computer readable memory responsive to the ambient air temperature and the output pressure of the compressor;
set the condenser fan speed to the selected condenser fan speed via the condenser fan control signal;
and
send an alarm signal via the alarm output when the suction pressure is less than a threshold suction pressure level and the ambient temperature is above a threshold temperature.

20 more elements

Dependencies are inferred from the claim text.

Controlling HVAC Condenser Fans Using Pressure Sensors

Life of this patent

Controlling HVAC Condenser Fans Using Pressure Sensors

Life of this patent

Abstract

Claims20