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Temperature control and fuel economy |
Written by Hailey Boss
Wednesday, 13 June 2007
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A typical running Volvo engine has variable cooling needs. It is not enough to basically have a basic cooling system composed of just a fan blade and radiator. To meet every demand of the engine, the Volvo Fan Clutch was constructed as an important component of the Volvo cooling system. Nearly all rear-wheel drive vehicles, including Volvo's S series, use fan clutches to control fan speed because of their ability to provide high volumes of air and good fuel economy. Despite their popularity, they are one of the least understood cooling components. The Volvo Fan Clutch has two basic types: the Non-Thermal, also known as the centrifugal clutch and the Thermal Fan Clutch. The first one, non-thermal Volvo Fan Clutch, is identified by a smooth, steel faceplate located on the front. This kind of fan clutch is a low cost alternative for typical standard thermal clutches. Non-thermal fan clutches spin at about 30 to 60 percent of the water pump speed. They are always engaged, and give less fuel savings than a thermal clutch. Because of this, they have a shorter life expectancy than their thermal counterparts. Heavy duty clutches are not replaceable by non-thermal ones. A thermal Volvo Fan Clutch, on the other hand, varies the fan speed with temperature of the air behind the radiator. Its high-speed operation yields maximum cooling effect. When operating in low speed, this fan clutch saves and reduces considerable amount of fuel consumption and noise respectively. It typically engages at about 170 degrees of radiator temperature - 30 degrees lower than the coolant. Its impervious characteristics give the thermal fan clutch a much longer life than a non-thermal clutch. How does a thermal Volvo Fan Clutch work? Air temperature coming through the radiator is sensed by the bi-metal thermal spring on the front of the thermal fan clutch. It expands and contracts as the air temperature of a valve inside the clutch changes. When cold, the silicone drive fluid is pumped from the working area to the main supply. When hot, the valve opens, allowing fluid from the reservoir to be transferred to the working area. As a result, fan speed increases. The clutch disengages as the air temperature decreases, closing the valve, and allowing the silicone fluid to be pumped back into the reservoir. No doubt, the Volvo Fan Clutch are designed, not just to control temperature, but to increase air volume and contribute to fuel economy. Article Source: http://www.ArticleBlast.com |
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