AN EXHAUST GAS HEATING AND ENERGY RECOVERY SYSTEM Field of the Invention

The present invention relates to an exhaust gas heating and energy recovery system which enables to enhance emission cycle performance and extra energy generation by heating the exhaust gas by using an energy generator and a heater, and which also enables use of recycling of this generated energy.

Background of the Invention

Exhaust gas recirculation (EGR) is a system aiming to reduce the heat generated as a result of combustion by recirculating a part of the exhaust gas back to the cylinders and thus to control nitrogen oxide gases (NOx) which are harmful for environment. It is particularly used widely in diesel engines. The exhaust gases are directed from the exhaust manifold to the intake duct via a tube in order to prevent formation of nitrogen oxides. This mixture of fresh air and exhaust gas is mixed with a certain amount of fuel by the engine control unit. The energy released as a result of combustion limits temperature of the gas in the cylinder due to the C0 ₂ coming from the exhaust gas and reduces NOx formation.

The particulate filter in diesel engines is used for fulfilling the Euro6 legal requirements for heavy commercial vehicles. The particulate filter filters the particulates in the exhaust gas produced as a result of combustion and reduces important pollutants such as nitrogen oxides (NOx), hydrocarbons (THC) and carbon monoxide (CO). The particulates accumulated in the filter are burned at certain periods by increasing the exhaust gas temperature above 550°C. This process is called regeneration. In addition, there are many catalyst systems in vehicles for reducing NOx gas. These catalyst systems should always remain hot in order to operate efficiently. In the currently used technique, the gas output from the engine is used to bring the exhaust system to a certain regime and the gas is directly discharged to the atmosphere without making use of its energy in any way. DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) catalysts perform depending on the temperature of the exhaust gas coming from the engine. The fact that the Diesel Particulate Filter retains the soot and burns N02 based soot based on the temperature is not sufficient for passive regeneration and the current temperature is not sufficient to perform this process. Since selective catalytic reduction catalyst temperature is not high enough during usage, preferred NOx circulation cannot be obtained. In order to pull the NOx levels to the desired level, exhaust gas recirculation system is used in the engine and the kinetic energy which is reduced when the vehicle is decelerating is given as heat to the environment; in other words it is not possible to make use of this energy. Since passive regeneration is not possible in diesel particulate filter due to the stated reasons, a high priced active regeneration system and a fuel injection system are required to be used. Furthermore, since the preferred NOx circulation cannot be attained because the selective catalytic reduction catalyst is not hot enough, it is compulsory to arrange a high priced EGR system to the engine. The kinetic energy reduced during braking cannot in any way be used to contribute to fuel economy but given to the environment as heat energy.

The European patent document no. EP0632188 (Al), an application in the state of the art, discloses about exhaust emission control in diesel engines. The system comprises a filter (5), an exhaust gas passage (2), an electric heater (6), an electric motor (M), an air pump (9) and a battery (11). When the filter collects a predetermined amount of the particulates, the heater and the pump are used to remove the particulates from the filter and the filter is regenerated. The heater and motor are driven by a signal transmitted based on the difference between a value of actual power and a predetermined target power value. Summary of the Invention

The objective of the present invention is to provide an exhaust gas heating and energy recovery system wherein a low PGM (precious metals such as Pt/Pd) level (low priced) system can be used since the diesel particulate filter will be hot enough to support passive regeneration.

Another objective of the present invention is to provide an exhaust gas heating and energy recovery system wherein EGR system is not used due to the increased efficiency in SCR system, and thus price advantage is achieved.

A further objective of the present invention is to provide an exhaust gas heating and energy recovery system which can be operated at high NOx low fuel economy regime and which thus provides advantage in fuel consumption.

Another objective of the present invention is to provide an exhaust gas heating and energy recovery system whose energy converter can be operated uninterruptedly since a part of the heat energy discharged to the outer environment as waste energy will be delivered to the exhaust system.

A further objective of the present invention is to provide an exhaust gas heating and energy recovery system which provides advantage in terms of fuel economy by providing extra torque to the engine which is recovered from the exhaust and kinetic energy of the vehicle.

Another objective of the present invention is to provide an exhaust gas heating and energy recovery system by which extra braking power is achieved whereby the load acting on the vehicle brakes is reduced. Detailed Description of the Invention An exhaust gas heating and energy recovery system developed to fulfill the objective of the present invention is illustrated in the accompanying figures, in which: Figure 1 is a schematic view of the engine exhaust component which does not have an exhaust gas heating and energy recovery system.

Figure 2 is a schematic view of the exhaust gas heating and energy recovery system. The components shown in the figures are given reference numbers as follows:

1. Exhaust gas heating and energy recovery system

2. Engine

3. Energy generator

4. Heater

5. Energy converter

A. EGR system

B. Turbo

C. Valve

D. Fuel injector

E. Catalyst

F. Filter

G. Thermometer

H. Clutch

I. Transmission box

J. Wheel

An exhaust gas heating and energy recovery system (1), which enables to enhance emission cycle performance and to generate extra energy by heating the exhaust gas, and which also enables use of recycling of this generated energy, basically comprises at least one engine (2) which generates power by converting chemical energy to mechanical energy,

at least one energy generator (3), which is positioned between the engine (2) and the wheel (J), and which converts the mechanical energy produced as a result of rotation of the wheel (J) preferably to electric energy and transfers this energy,

at least one heater (4) which is positioned before the catalysts (E), and which, by consuming the energy generated at the energy generator (3), enables to increase the current temperatures of the gases that are released as a result of combustion in the engine and that move in the exhaust direction,

at least one energy converter (5) which is positioned at the exhaust outlet after the catalysts (E), and which uses the energy in the gases which are burned and whose heat is increased in order to compensate for a part of the power consumed by the engine (2) and which thus allows less fuel consumption.

In the prior art, air input into the preferably internal combustion engine (2) is provided preferably through turbo (B) and this air controlled via the valve (C) produces a combustion here together with the fuel. As a result of combustion, chemical energy is converted to mechanical energy and produces torque power to the wheel (J) by the clutch (H) by means of the transmission box (I). Additionally, some burned gas is released to the environment as a result of the combustion. These hot exhaust gases that are released pass through a catalyst€ (preferably diesel oxidation catalyst) and also through a filter (preferably a diesel particulate filter). Then, it passes through different catalysts€ (for example selective catalytic reduction catalyst) and it is converted to water and nitrogen by ammonia gas which is dangerous to the release to the atmosphere. Temperature of the gas is measured via a thermometer (G). However, in this system, the desired NOx cycle cannot be obtained due to the fact that the SCR catalyst (E) is not hot as much as preferred and therefore an additional exhaust gas recirculation system (A) is added to the engine (2). During this process and discharge of the exhaust gas to the atmosphere, temperature of the exhaust gas cannot be utilized in any way, thus all of this energy is directly discharged to the atmosphere, in other words, all of it is wasted. Furthermore, this catalyzation process always continues as long as the engine (2) is running. Since this process is continuous, the filter (F) also continuously retains the soot in the exhaust gas and after a period of time these soot are required to be cleaned. In cases where load is applied on the vehicle, although exhaust gas is always hot since the engine (2) is running actively, when the vehicle is going downhill, not much load acts on the engine (2) and thus the exhaust gas is not hot and that causes more soot to be formed in the filter (F). At this point, a control unit which maintains general control of the vehicle passes from normal mode to active regeneration mode and injects fuel onto the hot exhaust gas from the fuel injector (D) located between the engine (2) and the catalyst (E). In this situation, temperature of the exhaust gas increases substantially and this gas burns the soot in the filter (F) while passing through the filter (F) and thus enables to clean the filter (F). Periodic cleaning of the filter (F) is performed this way. These said systems cause burden in terms of both production and cost.

In the preferred embodiment of the invention, the exhaust gas heating and energy recovery system (1) includes an engine (2) which converts chemical energy to mechanical energy the same way. The engine (2) mixes the air coming into it with fuel thereby producing combustion and movement of the vehicle is enabled with the mechanical energy produced as a result of this combustion. The exhaust gases resulting from this combustion first enter into the heater (4) before the catalyst (E) and are heated to a higher degree than their current temperature. The energy required for the heater (4) to heat the exhaust gas stated here is provided by means of the energy generator (3). In the case that the vehicle is moving downhill, this energy generator (3) is operated and it provides additional braking power to the vehicle; and if a force is applied to the vehicle (on a straight road or downhill), since the exhaust gas output from the engine (2) will be at the desired temperature, the energy generator (3) will be in passive mode and thus will not cause an additional load on the wheels (J). Since the exhaust gas output from the engine (2) is heated via a heater (4), a fuel injector (D) is not required as stated in the prior art and thus fuel is saved. As the exhaust gas is heated via a heater (4) when the vehicle is moving downhill, it enters into the filter (F) at a higher temperature than its current temperature, and therefore burns the soot inside the filter (F). As a result of burning of the soot as stated, soot accumulation does not occur in the filter (F) and hence active regeneration system is not required. The exhaust gas heating and energy recovery system (1) can be continuously operated in passive regeneration mode. Additionally, since the exhaust gas can be brought to the preferred temperature by means of the heater (4) and the NOx reduction ratio on SCR is high, the need for integration of an EGR (exhaust gas recirculation) system (A) for reducing NOx in the engine is eliminated. By means of this energy converter (5) which is mounted to the exhaust outlet after the catalysts (E), heat energy is converted to mechanical energy and transmitted to the clutch (H). In addition to the mechanical energy obtained as a result of the combustion taking place in the engine (2), a part of the energy required for moving the vehicle can also be provided by this energy converter (5). Thus, the energy converter (5) provides a part of the energy required for movement of the vehicle and thus enables fuel saving. In addition, since the exhaust gas is delivered to the energy converter (5) continuously at the same temperature, the energy converter (5) can also work continuously and this way significantly increases general efficiency.

Operation of the exhaust gas heating and energy recovery system (1) is described with example values as follows. Temperature of the exhaust gas formed as a result of the combustion that takes place in the engine (2) is approximately 250°C. Although N02 based soot burning process can be easily performed when the vehicle engine (2) is loaded, when the vehicle is going downhill, in other words when the vehicle engine is not loaded, it is not sufficient to burn the soot inside the filter (F). For that reason, a heater (4) is mounted between the engine (2) and the catalysts (E). The heater (4) supplies the energy it requires via the energy generator (3). By means of the said heater (4), temperature of the exhaust gas which is approximately 250°C is increased approximately to a temperature of 350°C. A temperature approximately 350°C is a temperature that is preferred for burning the soot in the filter (F). Since the exhaust gas will continuously be at the said temperature value by means of the heater (4), any additional system for burning the soot will not be required. Thus, the fuel injector (D) which increases gas temperature approximately to 600°C is not used thereby providing cost advantage. In addition, since the exhaust gas is delivered to the energy converter (5) continuously at the same temperature, efficiency of the energy converter (5) will be enhances as well as increasing the total energy provided to the energy converter.