The heating, venting, and air conditioning (HVAC) systems on today's commercial trucks are no longer afterthoughts in the design process. Randy Oetting, manager of International Truck & Engine Corp.'s Next Generation Vehicle project, says HVAC plays a key role in improving the driver environment of its new trucks.
“HVAC is critical to both driver comfort and productivity,” he explains. “You can improve a variety of driver-related features-steering and handling, acceleration response, belly room, etc.-but if the cab is too cold or too hot, or the windshield doesn't defrost properly, that's what drivers remember.”
As a consequence, International redesigned the HVAC system of what became its new High Performance (HP) Class 6-8 truck chassis, unveiled a few years ago. Larger vents and increased blower motor capacity enabled the OEM to boost cab cooling capability by 100% and heating by 200%, even though the cabs were larger than in previous models. Oetting says HVAC is a truck component that has its own life cycle value-helping boost driver productivity by increasing comfort and reducing fatigue. “It's providing value beyond the vehicle itself by allowing drivers to be more productive.”
That philosophy is driving a host of HVAC-related developments in the commercial truck market, from better electronic controls to auxiliary heating systems.
Delphi Automotive, for example, unveiled its prototype Intellek HVAC air quality sensor last year, designed to help prevent foul air from making its way into the passenger compartment. Delphi says this sensor, which goes into mass production in '04, essentially acts as an electronic nose, sniffing the air and detecting pollutants with a high degree of sensitivity. It's typically located near the air intake vent, at the base of the windshield.
“When low-quality air is detected, this sensor notifies the HVAC system, which can close the air intake vent and initiate the recirculation function for a short period of time until a vehicle leaves the area,” explains John Kirk, sensor development engineer. “The idea is to minimize the amount of low-quality air and odors being drawn into the vehicle.”
To boost HVAC efficiency and cut down on maintenance costs, Index Sensors and Controls has introduced the ACX-10 Air Conditioning Life Extender, a monitoring device that communicates with a vehicle's A/C system. The unit consists of a control module mounted in the engine compartment that protects air conditioning components against premature failure by monitoring refrigerant pressure and voltage.
Index says that both high and low refrigerant pressures can lead to rapid cycling of the A/C system, causing premature wear of the compressor, clutch, and hoses. The ACX-10 prevents rapid cycling of the A/C clutch by slowing the cycle rate to 15 seconds, cutting frequency by as much as 80%. The ACX-10 also detects big swings in voltage. Over-voltage damages an A/C system by creating excessive current and heat in the clutch coil, shortening clutch life. Under-voltage can cause the clutch to slip and burn out. When the ACX-10 detects either of these conditions, it temporarily disengages the A/C clutch until the voltage returns to normal.
Auxiliary HVAC systems are devices that tie into a truck's primary HVAC system to provide air conditioning and heat without operating the engine. Teleflex Proheat, for example, offers several such units. The I.C.E. Gen 3 provides heat and air conditioning, heat to the engine, and 110 V house electrical current for appliances and power tools. Its smaller cousin, the X45, provides only engine and cab heat. Both devices operate via small diesel generators, consuming 3/10th and 1/10th of a gallon of fuel per hour.
Those are just some examples of the how the profile of HVAC has been raised among truck manufacturers and operators alike. “Improving the entire driver environment in today's trucks is the key,” says International's Oetting. “HVAC … makes the cab a comfortable place for the driver to work.”
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Aux Generators Inc. 320
Delphi Automotive 321
Espar Heater Systems 322
IdleAire Technologies 323
Index Sensors & Controls 324
Pony Pack 325
Teleflex Morse 326
Webasto Thermosystems 327
Xantrex Technology 328 & Cab Comfort