Patent Application
20140137695
The field of this invention relates to an efficient heating system for a vehicle and more particularly an electric vehicle.
Heating systems for an interior of an electric vehicle pose particular problems that do not exist for vehicles run on internal combustion engines. Internal combustion engines produce vast quantities of heat as a waste product. Large radiators are used to dissipate much of the heat to the ambient atmosphere away from the engine. In winter, it is not much of problem to redirect some of the heated coolant that normally goes to the radiator to a heater core and have a fan blow air through the core to transfer the heat to the flowing air and fill the entire interior cabin of the vehicle with this warmed air. There are ducts that direct the heated air to various areas of the interior cabin, for example to the footwells to warm the feet, to the front vents in the instrument panel to heat the occupants hands and head and upper body, as well as to the front windshield and side windows for defrosting and demisting the windows for better vision. Some vehicles even duct the heated air to the back seats for providing more comfort to the back seat occupants.
While a heater core provides sufficient heat from an internal combustion engine, the heat is not available until the engine is sufficiently warmed up, which in certain cold winter days may take ten or more minutes. For diesel engines, the time may be even longer. To provide faster heat, some vehicles, particularly ones with diesel engines, are provided with electric ceramic heaters which heat up very quickly and provide heat blown by a fan into the interior cabin. Furthermore, many vehicles are now equipped with electric heated seats which provide warmth within a few minutes. Some luxury vehicles are also provided with electrically heated steering wheels to warm the hands. Some front windshields and rear windows have also been provided with electric defrosters to clear the windows faster.
The abundance of heat as a waste product from an engine does not exist for electric powered vehicles. Electric powered motors do not produce much heat as a waste product. There is not enough heat produced as a waste product to heat the entire cabin or even the footwell of a cabin. Heat must be purposefully created to warm a vehicle occupant. This produced heat is a commodity that drains the battery of the electric vehicle and can greatly decrease the electric mileage range of the battery. As such, heat production to heat the entire vehicle cabin is restricted in order not to overly drain the battery and overly reduce the electric mileage range per charge.
Blowing air around the cabin including the footwell is not an efficient way to warm occupants because most of the heated air inside the cabin is remote from the occupant and thus has no heating effect on the occupant. The moving air also has an undesirable evaporative cooling effect on the human body that is contrary to the desired goal of making an occupant feel warmth. When people get cold, the feet are often perceived as the coldest parts of the body. Conversely, when one's feet are cold, one will not perceive themselves as warm. Inadequate heating to the lower part of the vehicle cabin may be tolerable during short trips but longer durations of having cold feet are intolerable.
The central heat system of most vehicles including electric vehicles directs heated air downwardly from above the floor. While this system that pushes warmed air from above may be adequate when massive amounts of heat are available from a heater core, it is not the most efficient way of heating. Extra energy is used to push the warm air downwardly against natural inclination of the warm air to rise. Furthermore, the floor of the vehicle is often made of steel or other metal which efficiently conducts the cold from a cold ambient exterior atmosphere i.e. the floor is chilled from the outside. Although insulation layers may often be layered on the floor and carpet also provided, the chill often permeates through the layers from the outside and through the vehicle floor and is resistant to warming from heated air being pushed down from above. Thus during cold weather, and during extended trips, even though the upper cabin may be comfortable, occupants often have chilled feet. While passengers may lift their feet up and onto the seats in order to warm their feet away from the floor, this option is not available to the driver.
Efforts are being looked at to provide heat directly to the vehicle occupants without heating the entire interior and without blowing warmed air about the cabin. These focused heat efforts include heated seats in most electric vehicles because it is more efficient to heat the passenger directly. In fact certain electric vehicle manuals have instructions to use the heated seats rather than the central heater in order to preserve electric mileage range. Other research efforts are looking at radiant panels placed in strategic locations in the vehicle body such as the footwell, side door or instrument panel to provide radiant heat directed to the occupants. However, none of these have yet to reach the market place.
The problem with past heating efforts for vehicle interiors is that they do not make efficient use of electricity to warm the feet. Electric floor mats are also known that plug into the power outlet but these floor mats produce much heat that permeate to the cabin away from the occupant. These floor mats have been developed with electric wires passing through substantially the entire mat of which most of the area is not placed directly under the feet. However, if one looks at well-worn mats from many vehicles, one may notice that most of the wear is at one or two areas where the occupant most likely placed the right and left foot. The rest of the mat shows much less wear because the feet are rarely placed there or placed there for only short periods of time.
A driver of a vehicle also has his/her foot on the accelerator pedal a significant amount of time. The foot is often on the pedal even when coasting and not pushing down on the pedal. The left foot is often resting on a footrest that may be elevated relative to the rest of the footwell floor surface. Other passengers in the vehicle place their feet in particular locations in the footwell, whether in the front passenger seat or in the rear seats. Efficient use of heat energy directs one to not place radiant panels remote from the occupant or heat the entire floor mat or floor to adequately warm an occupant, particularly an occupant's feet.
What is needed is an improved and efficient focused heating system to directly warm the right foot and optionally the left foot of an occupant in an electric or other vehicle when the feet are on the accelerator pedal and the footrest or certain areas of the floor particularly during longer trips. What is also needed is radiant heat system which provides a greater concentration of heat on areas of the floor in a vehicle where the feet are most likely to be. Particular efforts need to be made to warm the feet which will give the occupant a perception and feeling of warmth.
In accordance with one aspect of the invention, an electrically powered heating system for a vehicle has a footrest built into a footwell of a vehicle having a structural substrate for supporting a driver's foot and an upper surface. A heating element is embedded in the footrest between the upper surface and the structural substrate for heating the footrest. The heating element has electric leads that are operably connectable to an electric power source for providing power to the heating element for producing heat.
In one embodiment, the heating element is electrically resistive to produce heat and is in the form of a convoluting wire covering a substantial area under the upper surface of the footrest. In another embodiment, the heating element being a radiant panel. It is preferable that an insulating layer is interposed between the heating element and the structural substrate.
In one embodiment, the heating system includes an accelerator pedal having an upper surface constructed for engagement with a driver's driving foot e.g. a right foot. A heating element is embedded in the accelerator pedal below the upper surface for heating the accelerator pedal. The heating element has electric leads that are operably connectable to an electric power source for providing power to the heating element for producing heat in the accelerator pedal.
It is also preferable to have a designated area in a floor covering in the footwell with a heating element under the surface for heating. One or more designated areas are sized to be approximately the size of a human foot and generally in a foot shape. It is preferable that the designated areas are visually distinctive from the rest of the floor covering.
Preferably any floor mat placed on the floor is shaped with a cut-out section for exposing one or more designated areas. One designated area for the right driver's foot may be activated with activation of a cruise control system for the vehicle.
In accordance with another embodiment of the invention, a floor covering in a footwell covers a floor of a vehicle and a designated area in the floor covering has a heating element under the surface for heating. The designated area is sized to be approximately the size of a human foot and the designated area is constructed to produce more dense heat energy than any floor area outside of the designated area. The designated area is generally in a foot shape. The designated area is preferably visually distinctive from the rest of the floor covering. In one embodiment, the floor covering is in the form of a removable mat.
According to another aspect of the invention, an accelerator pedal has an upper surface constructed for engagement with a driver's foot and a structural substrate below the upper surface. A heating element is embedded in the accelerator pedal below the upper surface for heating the accelerator pedal. The heating element has electric leads that are operably connectable to an electric power source for providing power to the heating element for producing heat. Preferably, the heating element is electrically resistive to produce heat. The heating element is in the form of a convoluting wire covering a substantial area under the upper surface of the accelerator pedal. In another embodiment, the heating element is in the form of a radiant panel. Preferably, an insulating layer is interposed between the heating element and the structural substrate.
Reference now is made to the accompanying drawings in which:
Referring now to
Heating elements 20, 22, and 24 are installed in the floor 14, the footrest 12 and in the accelerator pedal 16 respectively. Each heating element 20, 22, and 24 is a resistive electric wire 26 installed in a convoluting manner, for example sinusoidally, in the footrest 12, designated area 28 of the floor 14 and in the accelerator pedal 16. The shape of the designated area 28 is generally in the shape of a left shoe bottom or left foot as shown in
Furthermore, the designated area 28 may be visually distinctive from the rest of the floor to provide an intuitive indication 30 that this designated area 28 of the floor 14 is heated. Such visual indication 30 may for example be a different color, a shorter carpet pile than the rest of floor 14 or other indication such as stripes or other patterns such as wiggly heat lines.
Heating elements 20, 22, and 24 are installed in the footrest 12, floor 14 and accelerator pedal 16 in similar fashions so details will be described only for the heating element 24 in the accelerator pedal 16 while referring to
Another embodiment of the accelerator pedal 116 is shown in
An alternate embodiment 216 is shown in
If a mat 50 is desired to be placed on the floor 14 of the footwell 10, the mat 50 as shown in
In certain vehicles, a mat 60 as shown in
In certain upscale and most luxury vehicles, the vehicle is equipped with cruise control which allows the driver to remove the right foot from the accelerator pedal 16 for extended periods of time particularly during longer rides on relatively empty roads or expressways. For the cruise controlled equipped vehicles, it may also be desirable to have additional designated areas 228 and 328 shown in phantom on the floor 14 or mat 60 in the driver's footwell respectively to heat the right foot when it is removed from the accelerator pedal 16 and placed on the floor 14 or mat 60. These areas 228 and 328 are constructed in the same fashion as areas 28 and 128 except that the shape is for the right foot. The designated areas 228 and 328 are also suitable for passenger footwells where a passenger normally has both the left and right foot on the floor.
Control of the heating elements 20, 22 and 24 may be tied into the circuit with the heated seats and have an appropriate thermal switch to maximize comfort and prevent overheating and/or discomfort. The heating elements may have a separate switch conveniently located for example on the instrument panel. For most flexibility and most efficient use of the heater elements, each seat may have its own control switch. If there is a separate switch, it may also have heat levels in much the same fashion as used for heated seats. Suitable temperatures may be 105° F. for a low setting and may be as high as 120° F. for timed out cycles for example ten minutes. Thus, the heated elements may be tied to an electric circuit that has a timer control, for example, similar to one used for electric rear defrosters. In addition, areas 228 and 328 in the driver's footwell may be usually turned off and tied into the cruise control of the vehicle and activated when the cruise control is activated.
The heater element 24 in the accelerator is suitable for different styles of pedals. Certain pedals are pivotably mounted at a lower joint and extend upward. They are sized to cover substantially the entire length of the foot. Other pedals as shown are suspended from an operable hinge or pivot frame 32 above the pedal. These pedals are usually smaller in size and are usually positioned to be adjacent the distal end of the foot i.e. to be operated by the toe end of the foot. Heat provided to the distal end of the foot will efficiently warm the toes and the rest of the foot. In this fashion, radiant electric heat is efficiently delivered to areas that are directly under an occupant's feet. In this manner, wasted energy to empty areas of the vehicle cabin and areas not directly under a foot are greatly reduced.
In certain applications, radiant heat may still be delivered to other areas of the footwell 10 particularly the floor. In these situations where the entire footwell is heated, there will be higher density of heat energy delivered to designated areas 28, 128, 228 and 328 than to other areas of the floor.
Other variations and modifications are possible without departing from the scope and spirit of the present invention as defined by the appended claims.
The embodiments in which an exclusive property or privilege is claimed are defined as follows:
