US 9,809,088 B2
Controlling HVAC speed of condenser fans using pressure sensors
Douglas J. Hovel, Lincoln, IL (US); Erick A. Njos, Washington, IL (US); and Daniel A. Spurgeon, Washington, IL (US)
Assigned to Caterpillar Inc., Peoria, IL (US)
Filed by Caterpillar Inc., Peoria, IL (US)
Filed on Jun. 7, 2013, as Appl. No. 13/912,759.
Prior Publication US 2014/0360211 A1, Dec. 11, 2014
Int. Cl. F25B 49/00 (2006.01); B60H 1/32 (2006.01); B60H 1/00 (2006.01)
CPC B60H 1/3205 (2013.01) [B60H 1/00828 (2013.01); B60H 2001/3277 (2013.01)] 17 Claims
OG exemplary drawing
 
1. 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 that measures ambient temperature;
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 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 temperature and the output pressure of the compressor;
set a speed of the condenser fan to the selected condenser fan speed via the condenser fan control signal;
send an alarm signal via an alarm output when the suction pressure is less than a threshold suction pressure level and the ambient temperature is above a threshold temperature,
wherein a direction of the condenser fan is reversed, via the condenser fan control signal output, based on:
the condenser fan control data indicating a reverse direction based on the ambient temperature and the output pressure of the compressor, and
a previous reverse operation of the condenser fan occurred outside a minimum reverse cycle time.
 
6. A heat, ventilation, and air conditioning (HVAC) unit operated in an earthmoving machine, the HVAC unit comprising:
a compressor;
a condenser fluidly coupled to the compressor;
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 an ambient temperature sensor and the condenser fan, the controller including:
a processor,
a compressor control signal output that outputs a compressor signal to control the compressor,
a condenser fan control signal output that outputs the condenser fan control signal to control the condenser fan,
an ambient temperature input coupled to an ambient temperature sensor that measures ambient temperature, and
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, based on the ambient temperature and an output pressure of the compressor,
set a speed of the condenser fan to the selected condenser fan speed via the condenser fan control signal, and
reverse a direction of the condenser fan is reversed, via the condenser fan control signal output, based on:
the condenser fan control data indicating a reverse direction based on the ambient temperature and the output pressure of the compressor, and
a previous reverse operation of the condenser fan occurred outside a minimum reverse cycle time.
 
12. A controller for a heat, ventilation, and air conditioning (HVAC) unit operated in an earthmoving machine, the controller comprising:
a compressor control signal output operatively coupled to a compressor of the HVAC unit;
a condenser fan control signal output operatively coupled to a condenser fan of the HVAC unit;
a pressure sensor input that receives information regarding an output pressure of the compressor;
a temperature input that receives information regarding ambient temperature;
a processor coupled to the compressor control signal output, the condenser fan control signal output, the first pressure sensor input, and the temperature input; and
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, based on the ambient temperature and an output pressure of the compressor,
set a speed of the condenser fan to the selected condenser fan speed via the condenser fan control signal,
wherein a direction of the condenser fan is reversed, via the condenser fan control signal output, based on:
the condenser fan control data indicating a reverse direction based on the ambient temperature and the output pressure of the compressor, and
a previous reverse operation of the condenser fan occurred outside a minimum reverse cycle time.