Browse Prior Art Database

Variable Maximum Cooilng Fan Speed Strategy in a Motor Vehicle Based on Fan Loading

IP.com Disclosure Number: IPCOM000131694D
Publication Date: 2005-Nov-15
Document File: 1 page(s) / 28K

Publishing Venue

The IP.com Prior Art Database

Abstract

Cooling fan power consumption in a motor vehicle is at its highest for a given fan speed when the vehicle is not moving and when the temperature of the air entering the fan is low. Cooling fans employing electronic speed control often employ a fixed maximum fan speed based on fan/motor assembly power or current consumption limitations in these conditions to protect from fan power or current over consumption across the whole range of vehicle operating conditions. As the temperature of the air entering the cooling fan and the vehicle speed rise, the power or current required to turn the cooling fan at a given speed decreases due to a decrease in fan blade loading. Alternatively, for a given fan power or current consumption, the fan will spin faster with increasing vehicle speed and air temperature. When the fan spins faster, more air flows through the radiator and other heat exchangers utilizing the fan. This increases the ability of these devices to reject heat which improves the cooling performance they provide and affords the customer a wider range of vehicle operation due to the reduced likelihood of overheating. The cooling fan is typically needed most in high outside air temperature high powertrain heat rejection situations. High powertrain heat rejections typically occur at higher vehicle speeds as the powertrain has to work harder to push the vehicle down the road at higher speeds as compared to lower ones. The typical method for setting top fan speed, as described above, coupled with the unloading phenomena also described above, mean that the fan is typically top speed limited well below its true limits, as dictated by power or current consumption, in the situations where it is needed the most. This reduces the ability of the vehicle to cool and increases the chance of overheating unnecessarily. The idea proposed here is to employ a variable top fan speed strategy which will allow the fan to run faster as fan blade loading is decreased to improve vehicle cooling performance without excessive fan power or current consumption.

This text was extracted from a Microsoft Word document.
This is the abbreviated version, containing approximately 52% of the total text.

Title:

Variable Maximum Cooling Fan Speed Strategy in a Motor Vehicle based on Fan Loading

Description of Invention:

Cooling fan power consumption in a motor vehicle is at its highest for a given fan speed when the vehicle is not moving and when the temperature of the air entering the fan is low. Cooling fans employing electronic speed control often employ a fixed maximum fan speed based on fan/motor assembly power or current consumption limitations in these conditions to protect from fan power or current over consumption across the whole range of vehicle operating conditions. As the temperature of the air entering the cooling fan and the vehicle speed rise, the power or current required to turn the cooling fan at a given speed decreases due to a decrease in fan blade loading. Alternatively, for a given fan power or current consumption, the fan will spin faster with increasing vehicle speed and air temperature.  When the fan spins faster, more air flows through the radiator and other heat exchangers utilizing the fan.  This increases the ability of these devices to reject heat which improves the cooling performance they provide and affords the customer a wider range of vehicle operation due to the reduced likelihood of overheating.

The cooling fan is typically needed most in high outside air temperature high powertrain heat rejection situations. High powertrain heat rejections typically occur at higher vehicle speeds as the powertrain has to work harder to push the vehicle down the road at higher speeds as compared to lower ones. The typical method for setting top fan speed, as described above, coupled with the unloading phenomena also described above, mean that the fan is typically top speed limited well below its true limits, as dictated by power or current consumption, in the situations where it is needed the most. This reduces the ability of the vehicle to cool and increases the chance of overheating unnecessarily.

The idea proposed here is to employ a variable top fan speed strategy which will allow the fan to run faster as fan blade loading is decreased to improve vehicle cooling performance without excessive fan power or current consumption. 

There are multiple ways of doing this and two will be described here.  One method can be thought of as a feedback control method which employs direct...