Patent Application
20190047359
This document relates generally to the motor vehicle equipment field and, more particularly, to a new and improved apparatus and method provided for the direct heat exchange between exhaust gases and cabin air in a motor vehicle.
Internal combustion engines transform only a fraction of the total energy from fuel to mechanical energy. The remainder is lost as heat to the engine coolant and exhaust gases.
Common motor vehicle cabin heating devices rely upon heat exchange between the engine coolant and the cabin air in order to heat the passenger cabin. When a motor vehicle has been resting in low ambient temperature conditions, the engine coolant cools to the ambient temperature. Unfortunately, it takes a significant amount of time for the engine coolant to warm sufficiently to slowly heat the air being circulated through the passenger cabin. In addition, it should be appreciated that the removal of this heat energy from the engine coolant slows the process of engine warmup, which in turn increases fuel consumption and lowers fuel economy.
The new and improved apparatus provides for direct heat exchange between the engine exhaust gases and the cabin air without the use of any other intermediate working fluid which would slow down the process of cabin heating. Advantageously, exhaust energy is taken downstream from the emission reduction devices, such as the catalytic converter, so as to not compromise the normal after-treatment warmup process and thereby maintain combustion gas emissions within desired design parameters.
In accordance with the purposes and benefits described herein, an apparatus is provided for the direct exchange of heat between exhaust gases and cabin air in a motor vehicle. That apparatus comprises a heat exchanger having an exhaust gas inlet, an exhaust gas outlet, a cabin air inlet and a cabin air outlet.
That apparatus may further include an exhaust gas inlet conduit having a first end connected to an exhaust gas conduit and a second end connected to the exhaust gas inlet. Further, the apparatus may include an exhaust gas flow control valve at the first end.
The apparatus may further include an exhaust gas discharge conduit connected to the exhaust gas outlet. In addition, the apparatus may further include a cabin air inlet conduit connected to the cabin air inlet and a cabin air outlet conduit connected to the cabin air outlet.
Still further, the apparatus may include a cabin air circulation fan that circulates air through the cabin air inlet conduit, the heat exchanger and the cabin air outlet conduit.
Still further, the apparatus may include a controller. That controller may be configured to control operation of the exhaust gas flow control valve. In addition, the controller may be further configured to control operation of the cabin air circulation fan.
The apparatus may also include a cabin temperature monitor and an exhaust gas temperature monitor. Both of these monitors may be connected to the controller. In addition, in some embodiments the exhaust gas flow control valve may be connected downstream of a catalytic converter of the motor vehicle.
Some embodiments may also include a coolant and cabin air heat exchanger in addition to the exhaust gas and cabin air heat exchanger. In such an embodiment, the controller may control operation of both heat exchangers in a manner that maximizes the heating efficiency for the motor vehicle.
In accordance with yet another aspect, a method is provided for heating cabin air in a motor vehicle. That method comprises circulating exhaust gases and cabin air through a heat exchanger whereby heat is directly exchanged between the exhaust gases and the cabin air without the use of any other working fluid.
The method may further include the step of diverting exhaust gases toward the heat exchanger by operation of an exhaust gas flow control valve. In addition, the method may include locating that exhaust gas flow control valve downstream from a catalytic converter of the motor vehicle.
Still further, the method may include the step of configuring a controller to control operation of the exhaust gas flow control valve. In addition the method may include the step of circulating cabin air through the heat exchanger with a cabin air circulation fan. In such an embodiment the controller may be further configured to control operation of the cabin air circulation fan.
Still further, the method may include the step of exclusively heating the cabin air with exhaust gases in the heat exchanger. In other embodiments the method may include pairing the exhaust gas and cabin air heat exchanger with a motor vehicle coolant and cabin air heat exchanger. In such an embodiment the method may also include the step of configuring the controller to heat the cabin air with (a) exhaust gases in the exhaust gas and cabin air heat exchanger until the motor vehicle coolant reaches a predetermined temperature and (b) the motor vehicle coolant in the motor vehicle coolant and cabin air heat exchanger after the coolant reaches the predetermined temperature.
In the following description, there are shown and described several preferred embodiments of the apparatus and method. As it should be realized, the apparatus and method are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the apparatus and method as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.
The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate several aspects of the apparatus and method for direct heat exchange between exhaust gases and cabin air in a motor vehicle and together with the description serve to explain certain principles thereof.
Reference will now be made in detail to the present preferred embodiments of the exchanger, examples of which are illustrated in the accompanying drawing figures.
Reference is now made to
The apparatus 10 includes an exhaust gas and cabin air heat exchanger 12 having an exhaust gas inlet 14, an exhaust gas outlet 16, a cabin air inlet 18 and a cabin air outlet 20 whereby heat is directly exchanged between exhaust gases and cabin air of a motor vehicle.
As illustrated in
The apparatus 10 also includes an exhaust gas discharge conduit 32 connected to the exhaust gas outlet 16. In the illustrated embodiment, the exhaust gas discharge conduit 32 has a discharge end 34 connected to the exhaust gas conduit 26. A one-way flow control valve (not shown) may be provided in the exhaust gas discharge conduit 32 such as adjacent the discharge end 34. Such a one-way flow control valve ensures the flow of exhaust gases from the exhaust gas discharge conduit 32 into the exhaust gas conduit 26 of the motor vehicle.
As best illustrated in
As further illustrated in
Exhaust gas flow (a) through the exhaust gas inlet conduit 22 is illustrated by action arrow D, (b) through the exhaust gas and cabin air heat exchanger 12 is illustrated by action arrows E and (c) through the exhaust gas discharge conduit 32 is illustrated by action arrow F. As should be appreciated, the cabin air circulation passageways 42 and the exhaust gas circulation passageways 44 of the exhaust gas and cabin air heat exchanger 12 are fully isolated from one another by walls of material having a high thermal conductivity to allow for efficient and effective heat exchange between the hot exhaust gases and the circulating cabin air to be heated by those hot exhaust gases.
As best illustrated in
As further illustrated in
In summer or at other times when there is no request for heating the cabin air, the controller 50 sends a necessary signal to the actuator of the exhaust gas flow control valve 30 to cause that exhaust gas flow control valve to close off the inlet conduit 22 thereby routing 100% of the exhaust gas flow from the engine 56 and catalytic converter 58 upstream of that valve through the exhaust gas conduit 26 for discharge into the environment through the exhaust gas outlet 60. Thus, when the exhaust gas flow control valve 30 is in this position it should be appreciated that no heat is being exchanged with the cabin air in the exhaust gas and cabin air heat exchanger 12.
In contrast, when the cabin air temperature drops below a predetermined value or set point as indicated by the cabin air temperature monitor 54, the controller 50 responds to a heating request by adjusting the position of the exhaust gas flow control valve 30. As illustrated in
After initial warming of the passenger cabin to a predetermined temperature or set point as automatically or manually selected through the heating and ventilating and air conditioning (HVAC) system controls of the motor vehicle, the controller 50 sends a signal to the exhaust gas flow control valve actuator to place the exhaust gas flow control valve 30 at an intermediate position (see
In an alternative embodiment illustrated in
As illustrated in
Consistent with the above description, a method is provided of heating cabin air in a motor vehicle. That method includes the step of circulating exhaust gases and cabin air through an exhaust gas and cabin air heat exchanger 12 whereby heat is directly exchanged between the exhaust gases and the cabin air without use of any other working fluid.
The method may further include the step of diverting exhaust gases toward the exhaust gas and cabin air heat exchanger 12 by operation of an exhaust gas flow control valve 30. In addition, the method may include locating that exhaust gas flow control valve 30 downstream from the engine 56 and catalytic converter 58 of the motor vehicle where the diversion of exhaust gases will not compromise the normal after-treatment warmup process and environmental controls.
The method may also include configuring the controller 50 to control operation of the exhaust gas flow control valve 30. Further, the method may include circulating cabin air through the exhaust gas and cabin air heat exchanger 12 with a cabin air circulation fan 40. In such an embodiment, the method may further include the step of configuring the controller 50 to control operation of the cabin air circulation fan 40.
In one of many possible embodiments such as illustrated in
The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. For example,
