The invention relates to a system and a method for improving operating efficiency of a powertrain by controlling an aero shutter.
A shutter is typically a solid and stable covering for an opening. A shutter frequently consists of a frame and louvers or slats mounted within the frame.
Louvers may be fixed, i.e., having a permanently set angle with respect to the frame. Louvers may also be operable, i.e., having an angle that is adjustable with respect to the frame for permitting a desired amount of light, air, and/or liquid to pass from one side of the shutter to the other. Depending on the application and the construction of the frame, shutters can be mounted to fit within, or to overlap the opening. In addition to various functional purposes, particularly in architecture, shutters may also be employed for largely ornamental reasons.
In motor vehicles, a shutter may be employed to control and direct a stream of light and/or air to various vehicle compartments. Therefore, a shutter may be employed to enhance comfort of vehicle passengers, as well as for cooling a range of vehicle systems.
A method is disclosed for increasing operating efficiency of a powertrain in a vehicle by controlling airflow for cooling the powertrain. The vehicle includes a grille opening and a fan characterized by a predetermined size and capable of being selectively turned on and off. The method includes unrestricting the grille opening by selecting a fully opened position for an adjustable shutter arranged relative to the grille opening at or below a first predetermined vehicle speed, and turning the fan off. The method also includes unrestricting the grille opening by selecting the fully opened position for the shutter above the first predetermined vehicle speed and at or below a second predetermined vehicle speed under a high powertrain cooling load, and turning the fan on. The method additionally includes partially restricting the grille opening by selecting an intermediate position for the shutter above the second predetermined vehicle speed, and turning the fan off. The predetermined size of the fan together with selecting one of the fully opened and intermediate positions of the shutter at the respective predetermined vehicle speeds provides sufficient airflow through the grille opening to cool the powertrain.
When the employed fan is characterized by a size that is predetermined to be the minimum capable for sufficiently cooling the powertrain, such a fan serves to increase the operating efficiency of the powertrain due to decreased parasitic drag on the engine. Furthermore, controlling the shutter to decrease the size of the grille opening above the second predetermined vehicle speed limits the amount of high-speed ram airflow and improves aerodynamic efficiency of the vehicle. Such an improvement in the aerodynamic efficiency further serves to increase the operating efficiency of the powertrain.
The method may also include monitoring the ambient temperature and selecting and locking a predetermined position for the shutter at any vehicle speed when the ambient temperature is below a predetermined value, such as near and below freezing.
According to the method, the shutter may additionally employ a mechanism configured to select and lock a position for the shutter between and inclusive of the fully opened and fully closed. The shutter may be arranged either integral with or adjacent to the grille opening.
The above-mentioned acts of selecting the shutter positions between and inclusive of the fully opened and the fully closed via the mechanism, and turning the fan on and off may be accomplished by a controller. The powertrain may include an internal combustion engine, and the act of regulating of the shutter by the controller may be accomplished according to a load on the engine. The vehicle may include a heat exchanger, and the engine may be cooled by a fluid that is circulated through the heat exchanger such that the engine is cooled by the fluid. The vehicle may additionally include a sensor that is configured to sense a temperature of the fluid. Furthermore, the shutter may be regulated by the controller according to the sensed temperature of the fluid.
A system for increasing an operating efficiency of a powertrain and a vehicle that employs the above-described method for increasing an operating efficiency of an engine are also disclosed.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
Vehicle 10 additionally includes an air-to-fluid heat exchanger 16, i.e., a radiator, for circulating a cooling fluid shown by arrows 18 and 20, such as water or a specially formulated coolant, though the engine 14 to remove heat from the engine. A high-temperature coolant entering the heat exchanger 16 is represented by the arrow 18, and a reduced-temperature coolant being returned to the engine is represented by an arrow 20. Heat exchanger 16 is positioned behind the grille opening 12 for protection of the heat exchanger from various road-, and air-borne debris. The heat exchanger 16 may also be positioned in any other location, such as behind a passenger compartment, if, for example, the vehicle has a rear or a mid-engine configuration, as understood by those skilled in the art.
As shown in
Because fan 22 is driven by engine 14, size of the fan is typically selected based on the smallest fan that in combination with the available grille opening 12 is sufficient to cool the engine during severe or high load conditions imposed on vehicle 10. Typically, however, when the size of grille opening 12 is tailored to such severe load conditions, the grille opening generates significant aerodynamic drag on the vehicle which causes a loss in operating efficiency of engine 14. On the other hand, if the size of the grille opening 12 is chosen based on the aerodynamic and operating efficiency requirements at higher vehicle speeds, the size of fan 22 that is required to generate sufficient airflow at high load conditions becomes so great, that the fan generates significant parasitic drag on engine 14. Therefore, an adjustable or variable size for the grille opening 12 would permit fan 22 to be sized for minimum parasitic drag on the engine 14, while being capable of satisfying the high vehicle load cooling requirements. At the same time, such an adjustable grille opening 12 would permit selection of a smaller fan that would further serve to increase the operating efficiency of the powertrain.
Shutter 30 also includes a mechanism 44 configured to select and lock a desired position for the shutter between and inclusive of fully opened and fully closed. Mechanism 44 is configured to cause louvers 32-36 to rotate in tandem, i.e., substantially in unison, and permitting the shutter 30 to rotate into any of the available positions. Mechanism 44 may be adapted to select and lock either discrete intermediate position(s) of the louvers 32-36, or to infinitely vary position of the louvers between and inclusive of the fully opened and fully closed. Mechanism 44 acts to select the desired position for the shutter 30 when activated by any external means, as understood by those skilled in the art, such as an electric motor (not shown). Vehicle 10 also includes a controller 46, which may be an engine controller or a separate control unit, configured to regulate mechanism 44 for selecting the desired position of the shutter 30. Controller 46 may also be configured to operate the fan 22, if the fan is electrically driven, and a thermostat (not shown) that is configured to regulate the circulation of coolant, as understood by those skilled in the art.
Controller 46 is programmed to regulate mechanism 44 according to the load on engine 14 and, correspondingly, to the temperature of the coolant sensed by sensor 26. The temperature of the high-temperature coolant 18 is increased due to the heat produced by engine 14 under load. As known by those skilled in the art, a load on the engine is typically dependent on operating conditions imposed on the vehicle 10, such as going up a hill and/or pulling a trailer. The load on engine 14 generally drives up internal temperature of the engine, which in turn necessitates cooling of the engine for desired performance and reliability. Prior to exiting the engine 14, coolant is routed inside the engine in order to most effectively remove heat from critical engine components, such as bearings (not shown, but known by those skilled in the art). Typically, the coolant is continuously circulated by a fluid pump (not shown) between engine 14 and heat exchanger 16.
When the shutter 30 is fully closed, as depicted in
In a moving vehicle 10, airflow 24 at ambient temperature and traveling at a certain velocity with respect to the vehicle penetrates the vehicle's grille opening 12. Airflow 24 that moves relative to the vehicle 10 traveling at elevated vehicle speeds generates positive air pressure at grille opening 12, and is thus termed “RAM airflow”. In a vehicle 10 traveling at or below a first predetermined speed, including when the vehicle is stationary, airflow 24 at ambient temperature and traveling at a certain low velocity with respect to the vehicle penetrates the vehicle's grille opening 12. Airflow 24 that moves relative to the vehicle 10 traveling at or below the first predetermined speed generates a minimal positive pressure at grille opening 12. Nonetheless, air flow 24 at such low pressures is sufficient to cool the engine 14 at lower vehicle speeds and loads. The first predetermined vehicle speed is typically established during testing and development of vehicle 10. Thus, when shutter 30 is fully opened at or below the first predetermined speed, fan 22 may be turned off in order to reduce the parasitic load on engine 14 and improve the operating efficiency of the powertrain.
Although in a moving vehicle 10 airflow 24 generates some positive pressure at the grill opening 12, at certain vehicle speeds coupled with increased vehicle loads the velocity of airflow 24 may be insufficient to generate sufficient RAM airflow to cool engine 14. Such may be the case even when the shutter 30 is fully opened and the grille opening 12 is unrestricted. Vehicle loads increase significantly, for example, in situations when vehicle 10 is required to pull a trailer up a grade, especially during warmer, summer temperatures. In a vehicle 10 traveling above the first predetermined vehicle speed and at or below a second predetermined vehicle speed, airflow 24 at ambient temperature and traveling at a certain velocity with respect to the vehicle generates some measure of RAM airflow at grille opening 12.
The second predetermined vehicle speed is a speed above which the resultant volume of airflow 24 traveling through a partially restricted grille opening 12 is sufficient to remove heat from coolant 18 entering the heat exchanger 16 without turning on fan 22. Such second predetermined vehicle speed is typically established during testing and development of vehicle 10. As noted above, the RAM airflow generated between the first predetermined and the second predetermined vehicle speeds may, however, be insufficient to cool engine 14. With vehicle 10 operating under a high powertrain load below the second predetermined vehicle speed, grille opening 12 may need to be completely unrestricted and the fan 22 turned on to impart maximum airflow 24 to heat exchanger 16. Hence, depending on the speed and loading conditions of vehicle 10, fully opening the shutter 30 and turning the fan 22 on may be necessary to generate sufficient airflow 24 to lower the coolant temperature inside heat exchanger 16, and thereby cool engine 14.
In a vehicle 10 traveling above the second predetermined vehicle speed, airflow 24 at ambient temperature and traveling at a certain velocity with respect to the vehicle generates a significant RAM airflow at grille opening 12. As described above, the second predetermined vehicle speed is a speed above which the resultant volume of airflow 24 traveling through a partially restricted grille opening 12 is sufficient to remove heat from coolant 18 entering the heat exchanger 16 without turning on fan 22. Therefore, above the second predetermined vehicle speed, some particular intermediate position of shutter 30 may be selected, while fan 22 is turned off, thus permitting sufficient amount of airflow 24 to reach the heat exchanger 16 to thereby cool engine 14. Appropriate intermediate positions of shutter 30 corresponding to particular speed and load conditions may be established during testing and development of vehicle 10. Thus, controlling shutter 30 to decrease the size of grille opening 12 above the second predetermined vehicle speed limits the amount of high-speed RAM airflow and improves aerodynamic efficiency of vehicle 10 and the operating efficiency of its powertrain.
Ambient temperatures near and below freezing may present additional considerations for cooling of the powertrain in the vehicle 10. When the ambient temperature is below a predetermined value, i.e., near or below freezing, sufficient cooling of engine 14 may be achieved with the grille opening 12 either in a partially restricted or in a fully blocked state. At the same time, louvers 32-36 and mechanism 44 may freeze and become jammed at such low temperatures. Therefore, in order to prevent jamming of the shutter 30 in some unwanted position, when the ambient temperature is below the predetermined value, an appropriate predetermined position of shutter 30 may be selected and locked without regard to vehicle speed and load. The grille opening 12 may be placed in any position between and inclusive of the fully open and the fully restricted states via the predetermined position of the shutter 30 depending on the cooling requirements of the powertrain of vehicle 10.
The predetermined locked position or a number of discrete locked positions of the shutter 30 that would still permit sufficient cooling of the powertrain near and below freezing ambient temperatures may be established empirically during testing and development of the vehicle 10. The controller 46 may be employed to monitor the ambient temperature via a temperature sensor (not shown) and regulate and lock the position of the shutter 30 via the mechanism 44 in response to the ambient temperature being below the predetermined value. Depending on the vehicle load, the fan 22 may be either turned on or off via the controller 46 while the shutter 30 remains in the predetermined locked position. Full control over the selectable positions of shutter 30 may then be returned when the ambient temperature again rises above the predetermined value.
In frame 56, the method includes unrestricting the grille opening 12 by selecting the fully opened position for shutter 12 via controller 46, when vehicle 10 is subjected to a high powertrain cooling load and is traveling above the first predetermined speed and at or below the second predetermined speed. Additionally, in frame 56 the method includes, turning the fan 22 on via controller 46, with the result being that sufficient airflow is provided through the unrestricted grille opening 12 to cool the powertrain. Following frame 56, the method proceeds to frame 58, where it includes partially restricting the grille opening 12 by selecting the intermediate position for shutter 30 via controller 46 above the second predetermined vehicle speed. Additionally, in frame 58 the method includes turning the fan 22 off via controller 46, with the result being that sufficient airflow is provided through the partially restricted grille opening 12 to cool the powertrain.
Additionally, at or near freezing ambient temperatures, the method may proceed directly from frame 52 to frame 60. In frame 60, regardless of vehicle speed, the controller 46 regulates mechanism 44 to position and lock the shutter 30 in a predetermined position which may include a fully closed state. Overall, the regulation of fan 22 sized to generate sufficient airflow at high vehicle loading conditions, together with employing adjustable shutter 30 to tailor the size of grille opening 12 to the cooling requirements of engine 14, permits heretofore contradictory vehicle requirements to be met. Furthermore, the above described combination of fan 22 and shutter 30 results in increased operating efficiency of the powertrain in vehicle 10.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
4476820 | Nixon | Oct 1984 | A |
4756279 | Temmesfeld | Jul 1988 | A |
4779577 | Ritter et al. | Oct 1988 | A |
4924826 | Vinson | May 1990 | A |
5669311 | Hill et al. | Sep 1997 | A |
5899196 | Chite | May 1999 | A |
6142108 | Blichmann | Nov 2000 | A |
6145251 | Ricci | Nov 2000 | A |
6227153 | Till | May 2001 | B1 |
6230832 | von Mayenburg et al. | May 2001 | B1 |
6854544 | Vide | Feb 2005 | B2 |
7128026 | Braun et al. | Oct 2006 | B2 |
7644793 | Iwasaki et al. | Jan 2010 | B2 |
7766111 | Guilfoyle et al. | Aug 2010 | B2 |
7784576 | Guilfoyle et al. | Aug 2010 | B2 |
8281754 | Saida et al. | Oct 2012 | B2 |
20040226764 | Iwasaki et al. | Nov 2004 | A1 |
20060005790 | Braun et al. | Jan 2006 | A1 |
20100243352 | Watanabe et al. | Sep 2010 | A1 |
Number | Date | Country |
---|---|---|
19719792 | Nov 1998 | DE |
Number | Date | Country | |
---|---|---|---|
20120111652 A1 | May 2012 | US |