Vehicle including thermoelectric generator

A vehicle includes an internal combustion engine (ICE) selectable between a running state and a non-running state. A thermoelectric generator (TEG) is in thermal contact with the ICE for converting thermal energy from the ICE to output electrical energy. The vehicle has an electric pump for circulating a liquid coolant through a coolant circuit. The electric pump is selectively powerable by the electrical energy output from the TEG. The coolant circuit is in fluid communication with the ICE, a radiator, and the TEG; and the TEG is downstream of the radiator in the coolant circuit.

TECHNICAL FIELD

The present disclosure relates generally to heating or cooling an internal combustion engine.

BACKGROUND

A thermoelectric module is a semiconductor-based electronic component that may be used for electric power generation. When a temperature differential is applied across a thermoelectric module, DC electric power is generated. As such, a thermoelectric module may be used to convert thermal energy to electrical energy. In other applications, a thermoelectric module may be applied as a heat pump or Peltier cooler.

Internal combustion engines convert, by combustion of fuel, the chemical energy of the fuel into energy useable to do work. Typically, only a portion of the energy released in combustion of the fuel is converted by the internal combustion engine into desirable work. In some internal combustion engines, a significant portion of the energy of combustion is lost in the form of waste heat.

SUMMARY

A vehicle includes an internal combustion engine (ICE) selectable between a running state and a non-running state. A thermoelectric generator (TEG) is in thermal contact with the ICE for converting thermal energy from the ICE to output electrical energy. The vehicle has an electric pump for circulating a liquid coolant through a coolant circuit. The electric pump is selectively powerable by the electrical energy output from the TEG. The coolant circuit is in fluid communication with the ICE, a radiator, and the TEG; and the TEG is downstream of the radiator in the coolant circuit.

DETAILED DESCRIPTION

Examples of the vehicle and method disclosed herein utilize a thermoelectric generator (TEG) to convert thermal energy from the internal combustion engine (ICE) to usable electrical energy. When the ICE is in a running state, thermal energy is produced by the combustion of fuel. At least a portion of the thermal energy produced by the ICE is converted by the TEG to electrical energy, and at least a portion of the electrical energy is used to power an electric pump. The TEG may be in thermal contact with the ICE. For example, the TEG may be in contact with an exhaust system of the ICE. In the present disclosure, the exhaust system of an ICE is a part of the ICE. When the TEG is in thermal contact with the ICE, the liquid coolant cools a cold side of the TEG. The electric pump, selectably powerable by the electrical energy output from the TEG, circulates a liquid coolant through a coolant circuit. The coolant circuit is in fluid communication with the ICE, a radiator, and the TEG.

As used herein, “in thermal contact” means making surface-to-surface contact between bodies such that conductive heat transfer may occur. It is to be understood that a material such as “thermal paste,” a brazing material, or a welding material may be disposed between two bodies “in thermal contact.” It is not necessary for two bodies in thermal contact to be affixed to each other as long as they are in contact and conductive heat transfer can occur between the two bodies through the contacting surfaces.

Referring now toFIG. 1, an example of the vehicle10of the present disclosure is depicted. The vehicle10includes an internal combustion engine (ICE)12, a thermoelectric generator (TEG)14, an electric pump16, and a radiator18. The vehicle10may also include a Heating Ventilation and Air Conditioning (HVAC) module20, a radiator bypass valve22, and a source of DC power24that is separate and distinct from the TEG14(e.g., a DC power generator66or an electrical energy storage device46).

In the example shown inFIG. 1, the ICE12and the TEG14are in thermal contact, and the ICE12, the TEG14, and the radiator18are in fluid communication with a coolant circuit26, with the TEG14being downstream of the radiator18in the coolant circuit26. In this example, a portion of the thermal energy produced by the ICE12is transferred directly from the ICE12to the TEG14(e.g., by conduction from the exhaust system65), and the liquid coolant circulated through the coolant circuit26is used to cool the cold side58of one or more thermoelectric modules54of the TEG14(via a liquid cooled heat exchanger29). In this example, the liquid coolant may receive residual thermal energy68from the TEG14through the liquid cooled heat exchanger29.

The ICE12may be any engine that generates motive power by causing a combustion reaction with an oxidizer, such as oxygen, and a fuel, such as gasoline or diesel fuel inside the engine. The ICE12is selectable between a running state and a non-running state. As used herein, the running state means, the combustion reactions are occurring inside the ICE12. Conversely, the non-running state means the combustion reactions are not occurring inside the ICE12. The combustion reactions produce gases, such as carbon dioxide and water vapor, which apply force (e.g., to a piston) and produce the motive power. The combustion reaction also produces thermal energy. The combustion products, including exhaust gas are directed away from the ICE12by an exhaust system65of the ICE12. The exhaust system65may include, for example, an exhaust manifold, catalytic converter, muffler, exhaust pipe, exhaust system connectors, hangers, and sensors attached to the exhaust system. In this disclosure, the exhaust system65is included in the ICE12.

In some existing internal combustion engines, the thermal energy produced by the internal combustion engine is lost to the environment as waste heat. However, in the example of the vehicle10shown inFIG. 1, the ICE12and the TEG14are in thermal contact, and a portion of the thermal energy produced by the ICE12is directly transferred to the TEG14. The portion of the thermal energy that gets transferred to the TEG14is converted, at least in part, to useable electrical energy by the TEG14.

Examples of the liquid coolant circulating through the coolant circuit26include mixtures of water and coolant concentrate (antifreeze, an example of which is ethylene glycol) referred to in SAE J814 Engine Coolants, incorporated by reference herein. It is to be understood that the liquid coolant disclosed herein is not limited to water/antifreeze mixtures. For example, liquids including natural and synthetic motor oils, hydraulic fluids and silicone may be used as the liquid coolant. As depicted inFIG. 1, the liquid coolant (via the coolant circuit26) may flow through the radiator18to cool the liquid coolant. Once the liquid coolant is cooled by the radiator18, the liquid coolant may then cool the ICE12and/or a liquid cooled heat exchanger (TEG HX)29in thermal contact with the thermoelectric module (TEM)54. The radiator18may be a liquid to air heat exchanger, including a typical automotive radiator. The radiator18may have engine coolant flowing therethrough. It is to be understood that heat exchanged from the liquid coolant through the radiator18may be transferred directly through tubes and fins (not shown) of the radiator18, or there may be an intermediate heat exchanger, for example an end-tank cooler (not shown).

In the example of the present disclosure depicted inFIG. 1, the TEG14is to convert the thermal energy produced by the ICE12to output electrical energy. The TEG14includes at least one thermoelectric module54. Each thermoelectric module54has a hot side56disposed in thermal contact with the ICE12and a cold side58distal to the hot side56. A portion of the thermal energy produced by the ICE12is transferred to the hot side56of the thermoelectric module(s)54. Each thermoelectric module54converts the thermal energy transferred from the ICE12to electrical energy via a Seebeck effect for consumption or storage by the vehicle10. Electrical energy is depicted with dashed lines inFIG. 1. For example, electrical energy is shown coming out of the TEG controller62and being conducted to the fan50, Pump16, and the electrical energy storage device24,46. A liquid cooled heat exchanger29is disposed on the cold side58of each thermoelectric module54to transfer residual thermal energy from the thermoelectric module54to the liquid coolant. The liquid coolant is pumped through the liquid cooled heat exchanger29by the electric pump16via the coolant circuit26.

The thermoelectric module54may be an array (not shown) of thermoelectric modules54. The thermoelectric modules54in an array may be electrically connected to other thermoelectric modules54in the array in series, in parallel, or in a combination thereof.

Non-limiting examples of the thermoelectric module54are: the HZ-20 Thermoelectric Module available from Hi-Z Technology, Inc., 7606 Miramar Road, San Diego Calif. 92126-4210; the TG12-6 thermoelectric module available from Marlow Industries, Inc., 10451 Vista Park Rd, Dallas, Tex. 75238; the PowerCard-γ™ available from Alphabet Energy, 26225 Eden Landing Road, Suite D, Hayward, Calif. 94545; and Skutterudite Thermoelectric Modules available from Furukawa Co., Ltd., 1-25-13 Kannondai, Tsukuba, Ibaraki 305-0856, Japan. The TEG14may also include a TEG controller62. The TEG controller62may direct the electrical energy generated by the TEG14to the electrical load (e.g., the electric pump16, the electric fan50, the blower30, etc.).

In examples of the present disclosure, the TEG14may generate electrical energy from thermal energy produced by the ICE12while the ICE12is in the running state or the non-running state. In an example, the TEG14is capable of producing from about 1.5 Wh (Watt hours) to about 15 Wh of electrical energy after the ICE12has been switched from the running state to the non-running state.

An example was tested. A TEG was mounted on an exhaust system of a vehicle and the vehicle was subjected to a hard drive cycle to fully warm up the engine and exhaust system. In the tested example of the present disclosure, the TEG produced electrical power at a maximum of 312.85 Watts at time=0 that decayed exponentially to about 6 Watts at time=90 seconds. The time constant was about 22.73 seconds. Integrating the exponential power equation between the limits of 0 and 90 seconds shows that 6975 Watt Seconds (1.938 Watt Hours) of energy was generated in the tested example over the first 90 seconds. 1.938 Wh is sufficient to run a 5 Watt pump for about 23 minutes.

The electrical energy generated by the TEG14may be consumed by the electric pump16. The electric pump16circulates the liquid coolant through the coolant circuit26. The electric pump16may be any pump that runs on electrical energy and is capable of circulating the liquid coolant through the coolant circuit26. In some examples, the electric pump16may pump the liquid coolant through a cooling jacket64to cool the ICE12. As used herein, the cooling jacket64means a network of passageways defined in the ICE12(e.g., in the cylinder block around the cylinders, and in the cylinder head around the combustion chamber) to cool the ICE12with the liquid coolant from the coolant circuit26. As disclosed herein, in examples of the present disclosure, the liquid coolant may be used to keep portions of the ICE12warmer than the portions of the ICE12would be if the portions of the ICE12were allowed to cool without circulation of the liquid coolant.

The electric pump16is selectably powerable by the electrical energy output from the TEG14. The electric pump16may be powered by the TEG14when the ICE12is in the non-running state. The electric pump16may also be powered by a source of DC power24that is separate and distinct from the TEG14. The source of DC power24may be the DC power generator66or the electrical energy storage device46. Examples of an electrical energy storage device46are a chemical battery or a capacitor. The TEG14requires a temperature difference between the hot side56and the cold side58to generate electric power from the TEG14. Therefore, as used herein, “hot” and “cold” are relative to each other. “Hot” means having a higher temperature than “cold”, thereby creating a thermal gradient across the TEG14to generate electric power.

In the example shown inFIG. 1, the source of DC power24may selectably power the electric pump16to prime the TEG14with liquid coolant to cool the cold side58of the TEG14to initiate a generation of electric power by the TEG14. When the ICE12is in the running state, the ICE12may supply mechanical work to the DC power generator66(e.g., by turning an armature of the DC power generator66) and the DC power generator66may then convert the mechanical work from the ICE12to DC power, which may be used to power the electric pump16. The electrical energy storage device46may supply electrical energy to the electric pump16when the TEG14and the DC power generator66cannot supply sufficient electrical energy to power the electric pump16.

In examples of the present disclosure, the electrical energy generated by the TEG14may power an electric fan50. The electric fan50may help the radiator18cool the liquid coolant. In an example, the radiator18may include a series of thin tubes and/or fins through which the liquid coolant is circulated, allowing the liquid coolant to be cooled by the air surrounding the tubes and/or fins. The electric fan50may draw ambient air through the radiator18in response to a control signal. The ambient air drawn through the radiator18by the electric fan50may cool the liquid coolant as the liquid coolant flows through the radiator18. With forced air convection from the electric fan50, the radiator18may cool the liquid coolant passing through the radiator to a sufficiently low temperature to maintain the ICE12and/or other components of the vehicle10within operational temperature limits (i.e., under boilover temperature or chemical degradation limits). In some cases, it may be desirable to operate the electric fan50when the ICE12is in the non-running state to maintain the ICE12and/or other components of the vehicle10within the operational temperature limits. Thus, the term “operational temperature limits” as used herein does not imply that temperatures are maintained only when a component or the ICE12is operating.

The electric fan50is selectably powered by the electrical energy output from the TEG14. The electric fan50may be powered by the TEG14when the ICE12is in the non-running state and natural convection does not provide enough cooling power.

In the example shown inFIG. 1, the electric fan50may help the radiator18cool the liquid coolant upstream of the liquid cooled heat exchanger29via the coolant circuit26. In the example depicted inFIG. 1, the TEG14is downstream of the radiator18in the coolant circuit26. When the ICE12is in the running state, the ICE12may supply mechanical work to the DC power generator66(e.g., by turning an armature of the DC power generator66), and the DC power generator66may then convert the mechanical work from the ICE12to DC power, which may be used to power the electric fan50. The electrical energy storage device46may power the electric fan50when the TEG14and the DC power generator66cannot supply sufficient electrical energy to power the electric fan50and natural convection does not provide enough cooling power to the radiator18.

The electrical energy generated by the TEG14may also be consumed by a blower30of the HVAC module20. The HVAC module20may include, in addition to the blower30, a heater core32, a defrost outlet34, a floor/panel outlet36, and a heater control valve38. The blower30outputs air52through the HVAC module20. The heater core32is disposed downstream of the blower30to heat the air52from the blower30. The heater core32may be a liquid to air heat exchanger to transfer thermal energy from the liquid coolant to the air52output by the blower30. Thus, the liquid coolant may transport thermal energy from the ICE12to the heater core32. The defrost outlet34directs the heated air52toward a windshield, a window(s), and/or mirror(s). The floor/panel outlet(s)36direct the heated air52toward a floor or other location (e.g., toward passenger upper body area) of a passenger compartment of the vehicle10. The heater control valve38selectably regulates the flow of the liquid coolant through a heater core branch33of the coolant circuit26. The heater control valve38may be used to block the heater core branch33of the coolant circuit26to reduce the load on the electric pump16by directing the pumping energy to pumping coolant through a smaller volume of the open branches of the coolant circuit26.

The blower30is selectably powerable by the electrical energy output from the TEG14. The blower30may be powered by the TEG14when the ICE12is in the non-running state. When the ICE12is in the running state, the ICE12may perform mechanical work on the DC power generator66(e.g., by turning an armature of the DC power generator66) and the DC power generator66may then convert the mechanical work from the ICE12to DC power, which may be used to power the blower30. The electrical energy storage device46may power the blower30when the TEG14and the DC power generator66cannot supply sufficient electrical energy to power the blower30.

The electrical energy generated by the TEG14may also be stored in the electrical energy storage device46. The electrical energy storage device46may be any electrical energy storage device, such as a chemical battery (e.g., a lead-acid battery, a Nickel Cadmium battery, a Lithium Ion battery, etc.) or a capacitor. The electrical energy storage device46may be connected to a DC bus48. Through the DC bus48, the electrical energy storage device46may receive additional electrical power (e.g., from the DC power generator66) and may supply electrical power to various components of the vehicle10(e.g., the electric pump16, the electric fan50, the blower30, etc.).

Other non-limitative examples of electrical loads that may be powered by the electrical energy generated by the TEG14are entertainment systems, lighting, electric motors, solenoids, instruments, navigation systems, and communication systems.

As mentioned above, the vehicle10may also include a radiator bypass valve22. In an example, the radiator bypass valve22may be a conventional bimetallic spring thermostat. In other examples, the radiator bypass valve22may be operable to open/close under conditions that are in addition to, or instead of a coolant temperature. When the ICE12is in the non-running state, the radiator bypass valve22may selectably bypass a radiator branch of the coolant circuit26, in response to a coolant temperature being in a bypass temperature range and selectably open the radiator branch of the coolant circuit26in response to the coolant temperature being above a predetermined threshold. The bypass temperature range may be below about 100° C. For example, a conventional bimetallic spring thermostat may begin to open at about 95° C. and be fully open at about 100° C. In some examples, the bypass temperature range may be below a “warmed up” engine temperature of 90° C. In other examples, the bypass temperature may be below a temperature where engine friction drops, for example, about 60° C.

Since engine oil viscosity is typically temperature dependent, the bypass temperature range may depend on the engine oil specification for the engine. Allowing the radiator18to cool the ICE12to a lower temperature may prolong operation of the TEG14by making a greater temperature difference between the exhaust system65in the non-running state and the coolant, since the exhaust system65will typically cool faster than the engine cylinder block. The engine block (coolant) may be allowed to cool to a lower temperature when the vehicle10is parked compared to the vehicle10being in a start/stop situation.

A start/stop situation is encountered when the ICE12automatically turns off when the vehicle10is stopped, for example in traffic. When the driver releases the brake and depresses the accelerator, the ICE12automatically restarts. However, the vehicle systems may determine differences between a start/stop situation and the vehicle10being parked, for example, by monitoring sensors and switches in the vehicle10. For example, if the ICE12is turned off by the operator, for example by removing a key, or pressing a start/stop button in a keyless vehicle, the vehicle10may determine that the vehicle10has been parked.

By bypassing the radiator branch of the coolant circuit26, the radiator bypass valve22allows the vehicle10to preserve the latent thermal energy produced by the ICE12, which allows more thermal energy to be transported to the heater core32. Thus, the heater core32may provide more heat to the air52from the blower30. In the example shown inFIG. 1, the radiator bypass valve22may bypass the radiator branch of the coolant circuit26when there is enough temperature difference across the TEG14to generate electrical energy without cooling the liquid coolant in the radiator18. When the ICE12is too hot (e.g., at a temperature above the threshold temperature), the radiator bypass valve22, by opening the radiator branch of the coolant circuit26, allows the ICE12to be cooled more quickly by rejecting heat into the environment70via the radiator18.

In examples of the present disclosure, the ICE12may be part of a hybrid powertrain40. AlthoughFIG. 1includes the hybrid powertrain40, it is to be understood that some examples include the ICE12, but do not include the electric drive motor42or the drive battery44. Such examples would not be hybrid vehicles. The hybrid powertrain40may include, in addition to the ICE12, an electric motor42and a drive battery44. The electric motor42may selectably power at least one drive wheel (not shown) of the vehicle10. The coolant circuit26may be in fluid communication with the electric motor42and/or the drive battery44. Thermal energy from the electric motor42and/or the drive battery44may be transferred to the liquid coolant circulating within the coolant circuit26. The liquid coolant may then selectably transport the thermal energy from the electric motor42and/or the drive battery44to the ICE12or the heater core32. The ICE12may be in a non-running state when the electric motor42powers at least one drive wheel of the vehicle10. The TEG14may power the electric pump16to keep the ICE12warmed up and ready to run more cleanly and efficiently when started in a hybrid powertrain40.

FIG. 2AandFIG. 2Btogether are a flow chart depicting a method100of cooling an internal combustion engine (ICE) of a vehicle as disclosed herein. The method100includes “starting the ICE using electrical energy from an electrical energy storage device” as shown the box marked with reference numeral105. “Running the ICE, thereby producing thermal energy” is at110. “Converting, with a thermoelectric generator (TEG), a portion of the thermal energy to electrical energy for consumption or storage by an electrical load” is at115. “Powering an electric pump with at least a portion of the electrical energy” is at120. “Wherein: the electric pump circulates a liquid coolant through a coolant circuit; the coolant circuit is in fluid communication with the ICE and the TEG; and the liquid coolant cools the ICE” is at125.

“Wherein the converting of the portion of the thermal energy to electrical energy is accomplished when the ICE is in a non-running state” is at130. “Valving off a portion of the coolant circuit to reduce a load on the electric pump” is at135.

“Wherein the powering of the electric pump is accomplished with additional electrical energy from the electrical energy storage device” is at140. “Wherein the powering of the electric pump is accomplished without additional electrical energy from the electrical energy storage device” is at150. “Wherein: the coolant circuit is in fluid communication with a heater core; the liquid coolant transfers an other portion of the thermal energy to the heater core; and the heater core transfers the other portion of the thermal energy to increase a temperature of a passenger compartment of the vehicle, to defog a window of the vehicle, or to both increase the temperature of the passenger compartment and defog the window” is at160. Connector “A” shows how the portion of the flow chart depicted inFIG. 2Ais connected to the portion of the flow chart depicted inFIG. 2B.

“Determining a temperature of the liquid coolant” is at180. “Comparing the temperature of the liquid coolant to a fan threshold temperature” is at185. “Activating an electric fan selectably powered by the TEG to draw ambient air through the radiator if the temperature of the liquid coolant is greater than the fan threshold temperature” is at190. “Deactivating the electric fan if the temperature of the liquid coolant is less than or equal to the fan threshold temperature” is at195.

It is to be understood that, in examples of the present disclosure, the coolant may be used to heat portions of the ICE12. For example, the TEG14may be mounted to the exhaust system65. Heat from the exhaust system65may be transferred to the coolant through the TEG14. The coolant may then be pumped through the cooling jacket64to heat, or slow the rate of cooling, of portions of the ICE12in the non-running state.

The method may also cause the ICE12to reach a stable operating temperature more quickly than without the TEG14. In examples, a stable operating temperature for an ICE12of the present disclosure is about 90 degrees C. to about 105 degrees C. in the cooling jacket64.

It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range from about 1.5 Wh to about 15 Wh should be interpreted to include not only the explicitly recited limits of about 1.5 Wh to about 15 Wh, but also to include individual values, such as 1.8 Wh, 10 Wh, 11 Wh, 14 Wh, etc., and sub-ranges, such as from about 1.5 Wh to about 11 Wh, from about 8 Wh to about 12 Wh, from about 10 Wh to about 13 Wh, etc. Furthermore, when “about” is utilized to describe a value, this is meant to encompass minor variations (up to +/−10%) from the stated value.

Further, it is to be understood that the terms connect/connected/connection”, “contact/contacting”, and/or the like are broadly defined herein to encompass a variety of divergent connected/contacting arrangements and assembly techniques. These arrangements and techniques include, but are not limited to (1) the direct communication between one component and another component with no intervening components therebetween; and (2) the communication of one component and another component with one or more components therebetween, provided that the one component being “connected to”/“in contact with” the other component is somehow in operative communication with the other component (notwithstanding the presence of one or more additional components therebetween).