GB2608401A

GB2608401A - Exhaust heat recovery system for a conventional vehicle as well as hybrid vehicle

Info

Publication number: GB2608401A
Application number: GB2109398.4A
Authority: GB
Inventors: O'donnell Lee; Schmelzle Tobias
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2023-01-04
Also published as: GB202109398D0

Abstract

An exhaust heat recovery system 10 for a vehicle, comprising an internal combustion engine 12 for driving the vehicle, a heat exchange circuit 14 through which a coolant may flow, the heat exchange circuit 14 being configured to exchange heat at least indirectly between the internal combustion engine 12 and the coolant flowing through the heat exchange circuit 14. An exhaust system (16) through which the exhaust gas of the internal combustion engine 12 may flow, comprising at least one catalyst 22 for the aftertreatment of the exhaust gas, and a heat exchanger 24 jacketing the catalyst 22, the heat exchanger 24 being arranged in the heat exchange circuit 14 such that heat may be exchanged between the coolant and the catalyst 22 via the heat exchanger 24. The exhaust heat recovery system provides combined exhaust heat recovery and catalyst warming.

Description

EXHAUST HEAT RECOVERY SYSTEM FOR A CONVENTIONAL VEHICLE AS WELL

AS HYBRID VEHICLE

FIELD OF THE INVENTION

[0001] The invention relates to an exhaust heat recovery system for a conventional vehicle as well as a hybrid vehicle.

BACKGROUND INFORMATION

[0002] WO 2019/116589 Al shows a hybrid vehicle catalyst warm-up control method. Furthermore, US 2017/0305411 Al shows a method in which an exhaust from one or more cylinders of a multiple cylinder combustion engine is coupled to an intake manifold of the engine. Moreover, JP 2009-227039 A shows a hybrid vehicle catalyst warm-up controller.

SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide a method for combined exhaust heat recovery and catalyst warming for a conventional vehicle as well as a hybrid vehicle such that a particularly efficient and low-emission operation may be realized.

[0004] This object is solved by an exhaust heat recovery system having the features of patent claims 1 as well as a hybrid vehicle having the features of patent claim 5. Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.

[0005] A first aspect of the present invention relates to an exhaust heat recovery system for a vehicle. The exhaust heat recovery system is also referred to as an exhaust heat energy recovery system. The exhaust heat recovery system comprises an internal which a coolant may tlow. Preterably, the coolant may be a liquid coolant. For example, the coolant may contain at least water. The heat exchange circuit is configured to exchange heat at least indirectly between the combustion engine and the coolant flowing through the heat exchange circuit. The exhaust heat recovery system further comprises an exhaust system through which an exhaust gas of the internal combustion engine may flow. For example, the internal combustion engine provides the exhaust gas in a fired operation of the internal combustion engine. In this regard, for example, the internal combustion engine is operated in the fired operation in order to drive the vehicle by the internal combustion engine. In the fired operation, combustion processes take place in the internal combustion engine. In the respective combustion process, a mixture comprising at least air and fuel is burnt such that the exhaust gas is produced. The exhaust gas may flow out of the internal combustion engine, into the exhaust system and through the exhaust system.

[0006] The exhaust system comprises at least one catalyst through which the exhaust gas may flow. The catalyst is configured for an after-treatment of the exhaust gas such that, for example, at least one first substance contained in the exhaust gas may be converted into at least one second substance being different from the first substance by the catalyst. This means that, for example, the catalyst may be configured to support or effect at least one chemical reaction in or by which the first substance is converted into the second substance.

[0007] Moreover, the exhaust heat recovery system comprises a heat exchanger jacketing the catalyst. Preferably, the heat exchanger is a built-in heat exchanger which is built in the catalyst such that, for example, the catalyst and the heat exchanger form a module which is, preferably, per se or considered on its own an independently assembled module. The heat exchanger is arranged in the heat exchange circuit such that the coolant may flow through the heat exchanger. Since, preferably, the coolant may be liquid, the heat exchanger may be configured as a liquid heat exchanger. Since the heat exchanger is arranged in the heat exchange circuit and jackets the catalyst, heat may be exchanged between the coolant and the catalyst via the heat exchanger. Thus, the catalyst may be cooled and/or heated, and the coolant may be heated and/or cooled. For example, when a first temperature of the coolant is higher than a second temperature of the catalyst, heat may be transferred from the coolant to the catalyst via the heat catalyst to the coolant via the heat exchanger thereby cooling the catalyst and heating the coolant. As a consequence, for example, the internal combustion engine may be heated by the heated coolant. Thus, by the exhaust heat recovery system according to the present invention, heat may be exchanged between the coolant and the catalyst, in particular between the internal combustion engine and the catalyst, in a particularly need-based manner such that a particularly efficient and low-emission operation may be realized.

[0008] Further advantages, features, and details of the invention derive from the following description of a preferred embodiment as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone may be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The novel features and characteristic of the disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0010] The drawings show in: [0011] Fig. 1 is a schematic view of an exhaust heat recovery system for a vehicle, in particular a hybrid vehicle.

[0012] Fig. 2 shows diagrams for illustrating an operation of the exhaust heat recovery system.

DETAILED DESCRIPTION

[0014] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0015] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0016] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by "comprises" or "comprise' does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0017] In the following detailed description of the embodiment of the disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0018] Fig. 1 is a schematic view of an exhaust heat recovery system 10 for a vehicle. This means that the vehicle, in its completely assembled state, comprises the exhaust heat recovery system 10. Preferably, the vehicle may be configured as a hybrid vehicle.

comprises the internal combustion engine 12 which is configured to drive the vehicle. In order to drive the vehicle by the internal combustion engine 12, the internal combustion engine 12 is operated in a fired operation. In the fired operation of the internal combustion engine 12, combustion processes take place in the internal combustion engine 12. In the respective combustion process, a mixture comprising at least fuel and air is burnt in the internal combustion engine 12 thereby producing an exhaust gas of the internal combustion engine 12. Thus, in the fired operation, the internal combustion engine 12 provides the exhaust gas. Since, preferably, the vehicle may be configured as a hybrid vehicle, the vehicle may comprise at least one electric machine configured to electrically drive the vehicle. Thus, for example, in order to, in particular purely, electrically drive the vehicle by the electric machine, the electric machine is operated in a motor mode and thus as an electric motor. For example, during a time span during which the vehicle is electrically driven by the electric machine, the internal combustion engine 12 may be switched off such that, during said time span, exhaust gas resulting from combustion processes are not provided by the internal combustion engine 12 since, during the time span, combustion processes do not take place in the internal combustion engine 12.

[0020] The exhaust heat recovery system 10 comprises a heat exchange circuit 14 through which a coolant may flow. Preferably, the coolant is a liquid (i.e. a liquid coolant). As will be described in greater detail below, the heat exchange circuit 14 is configured to exchange heat at least indirectly between the internal combustion engine 12 and the coolant flowing through the heat exchange circuit 14.

[0021] The exhaust heat recovery system 10 further comprises an exhaust system 16 through which said exhaust gas resulting from combustion processes in the internal combustion engine 12 may flow. In Fig. 1, an arrow 18 (i.e. exhaust flow in 18) illustrates the exhaust gas flowing into the exhaust system 16, and an arrow 20 (i.e. exhaust flow out 20) illustrates the exhaust gas flowing through and/or out of the exhaust system 16. This means that the exhaust gas of the internal combustion engine 12 (i.e. provided by the internal combustion engine 12 in the fired operation) may flow through the exhaust system 16. The exhaust system 16 comprises at least one exhaust catalyst 22 through which the exhaust gas may flow. The catalyst 22 is configured for an after-treatment of [0022] In order to realize a particularly efficient and low emission operation, the exhaust heat recovery system 10 comprises a jacketed heat exchanger 24 jacketing the catalyst 22. Furthermore, the heat exchanger 24 is arranged in the heat exchange circuit 14 such that the coolant may flow through the heat exchanger 24. For example, the heat exchanger 24 forms a jacket surrounding the catalyst 22, wherein the coolant may flow through the jacket. Thus, heat may be exchanged between the coolant and the catalyst 22 via the heat exchanger 24.

[0023] For example, the internal combustion engine 12 may be arranged, in particular directly, in the heat exchange circuit 14 such that the coolant flowing through the heat exchange circuit 14 may flow through the internal combustion engine 12. In this regard, for example, the internal combustion engine 12 may comprise at least one coolant passage 26 arranged in the heat exchange circuit 14 such that the coolant may flow through the coolant passage 26 and thus the internal combustion engine 12. Preferably, the internal combustion engine 12 may comprise a plurality of coolant passages arranged in the heat exchange circuit 14. Thus, for example, heat may be exchanged, in particular directly, between the internal combustion engine 12 and the coolant flowing through the heat exchange circuit 14 and thus the internal combustion engine 12. If a first temperature of the coolant flowing through the heat exchange circuit 14 and thus the internal combustion engine 12 is higher than a second temperature of the internal combustion engine 12, heat may be transferred, in particular directly, from the coolant to the internal combustion engine 12 thereby cooling the coolant and heating the internal combustion engine 12. If, for example, the first temperature is lower than the second temperature, heat may be transferred, in particular directly, from the internal combustion engine 12 to the coolant flowing through the internal combustion engine 12 thereby cooling the internal combustion engine 12 and heating the coolant.

[0024] If the first temperature or a third temperature of the coolant is higher than a fourth temperature of the catalyst 22, heat may be transferred from the coolant to the catalyst 22 via the heat exchanger 24 thereby cooling the coolant and heating the catalyst 22. If, for example, the first or third temperature of the coolant is lower than the fourth temperature of the catalyst 22, heat may be transferred from the catalyst 22 to the coolant via the heat exchanger 24 thereby cooling the catalyst 22 and heating the coolant. Thus, a way that heat is transterred from the internal combustion engine 12 to the coolant and from the coolant to the catalyst 22. Moreover, by the coolant and the heat exchanger 24, the internal combustion engine 12 may be heated using heat, in particular waste heat, contained in the exhaust gas, in particular in such a way that heat contained in the exhaust gas may be transferred from the exhaust gas to the coolant via the catalyst 22 and the heat exchanger 24 thereby heating the coolant. The heated coolant may be used to heat the internal combustion engine 12, in particular via the coolant passage 26. Thus, the exhaust heat recovery system 10 is a system for combined exhaust heat recovery and catalyst warming. Thus, by the exhaust heat recovery system 10, a method for combined exhaust heat recovery and catalyst warming may be realized. Particularly, by the exhaust heat recovery system 10, two beneficial processes may be integrated into the catalyst 22 which, in the embodiment shown in Fig. 1, is configured as a hybrid vehicle catalyst. This will allow a two-way energy transfer between the internal combustion engine 12 and the catalyst 22 to benefit vehicle efficiency and reduce emissions during different real world driving conditions.

[0025] The exhaust heat recovery system 10 may be used to increase an engine coolant temperature more quickly through the built-in liquid heat exchanger 24 jacketing the catalyst 22. For example, said engine coolant temperature is a temperature of an engine coolant which may be said coolant flowing through the heat exchange circuit 14. By increasing the engine coolant temperature particularly quickly, engine efficiency may be increased, and emission output may be reduced, in particular during a warm-up phase of the internal combustion engine 12. Moreover, by the exhaust heat recovery system 10, an activation temperature state of the catalyst 22 may be prolonged, in particular during engine-off hybrid conditions (i.e. during time spans during which the internal combustion engine 12 is switched off and, for example, the vehicle is electrically driven by the electric machine). Traditional engine catalysts will cool in ambient conditions through air passing around the catalyst exterior surface while the engine is off for hybrid vehicles. If the temperature reduces below the catalyst activation temperature, vehicle emissions may increase once the engine is restarted until the activation temperature is once again reached. To prolong the time the catalyst 22 remains in its active temperature range, the coolant which may be said engine coolant is circulated through the heat exchanger 24 (i.e. said jacket) to maintain, for example, a +100 degrees Celsius (fully warm engine) [0026] In Fig. 2, a gained efficiency is indicated at 28, and reduced emissions for hybrid restart are indicated at 30. As shown in Fig. 1, the heat exchanger 24 comprises at least one inlet 32 via which the coolant may be introduced into the heat exchanger 24. Moreover, the heat exchanger 24 may comprise at least one outlet 34 via which the coolant may be guided out of the heat exchanger 24. In the embodiment shown in Fig. 2, the heat exchanger 24 comprises a second outlet 36 via which the coolant may be guided out of the heat exchanger 24. The inlet 32 is also referred to as Om wherein the outlet 34 is also referred to as 0"1, and the outlet 36 is also referred to as ()max. For example, in Fig. 2, "ON (00.0" means that the outlet 34 is open, in particular whilst the outlet 36 is closed. For example, in Fig. 2, "ON (Gym)" means that the outlet 36 is open, in particular whilst the outlet 34 is open or closed.

[0027] Moreover, in the embodiment shown in Fig. 1, the exhaust recovery system 10 comprises a pump 38 configured to convey the coolant through the heat exchange circuit 14. Preferably, the pump 38 is an electrically operable pump (i.e. an electric pump). The pump 38 is also referred to as an exhaust heat recovery pump (EHRP). Moreover, the internal combustion engine 12 is also referred to as an engine. Thus, in Fig. 2, a graph 40 illustrates the second temperature of the internal combustion engine 12 and/or the engine coolant temperature. A graph 42 illustrates engine emissions, and the graph 44 illustrates engine states of the internal combustion engine 12. Furthermore, a graph 46 illustrates states of the EHRP. When the pump 38 is off (OFF), the pump 38 is switched off. Moreover, a graph 48 illustrates a state of a thermostat of the internal combustion engine 12, the thermostat being also referred to as an engine thermostat.

[0028] As shown in Fig. 1, the heat exchange circuit 14 may comprise a branch 50 through which the coolant flowing through the outlet 36 when the outlet 36 is open may flow. The exhaust heat recovery system 10 comprises a cooler 52 which is also referred to as a bypass cooler. The cooler 52 is additional such that, for example, the cooler 52 is an additional bypass cooler. For example, the cooler 52 is configured to cool the coolant flowing through the cooler 52. As shown in Fig. 1, the cooler 52 may be arranged upstream of the coolant passage 26 and thus the internal combustion engine 12 in the heat exchange circuit 14. Thus, for example, the coolant passage 26 may illustrate the internal combustion engine 12 being directly arranged in the first heat exchange circuit the internal combustion engine 12, as the internal combustion engine 12 itself is also trying to reject heat as much as possible. The feature that the cooler 52 is active is understood to mean that the coolant flows through the cooler 52 and is thereby cooled by the cooler 52.

[0029] Particularly, the following advantages may be realized by the exhaust heat recovery system 10: - improved emissions performance - improved thermal efficiency of the engine - improved fuel consumption - improved passenger experience (cabin heat available in reduced time) 12 internal combustion engine 14 heat exchange circuit 16 exhaust system 18 exhaust flow in exhaust flow out 22 exhaust catalyst 24 jacketed heat exchanger 26 coolant passage to engine 28 gained efficieny reduced emissions 32 coolant inlet 34 coolant outlet 36 coolant outlet 38 exhaust heat recovery pump engine coolant temperature graph 42 engine tailpipe emissions graph 44 engine state graph 46 exhaust heat recover pump state graph 48 engine coolant thermostat state graph auxiliary cooler circuit 52 auxiliary cooler

Claims

CLAIMS1. An exhaust heat recovery system (10) for a vehicle, comprising: an internal combustion engine (12) for driving the vehicle; a heat exchange circuit (14) through which a coolant may flow, the heat exchange circuit (14) being configured to exchange heat at least indirectly between the internal combustion engine (12) and the coolant flowing through the heat exchange circuit (14); -an exhaust system (16) through which an exhaust gas of the internal combustion engine (12) may flow, the exhaust system (16) comprising at least one catalyst (22) for an aftertreatment of the exhaust gas; and a heat exchanger (24) jacketing the catalyst (22), the heat exchanger (24) being arranged in the heat exchange circuit (14) such that heat may be exchanged between the coolant and the catalyst (22) via the heat exchanger (24).
2. The exhaust heat recovery system (10) according to claim 1, wherein a pump (38) is arranged in the heat exchange circuit (14), the pump (38) being configured to convey the coolant through the heat exchange circuit (14).
3. The exhaust heat recovery system (10) according to claim 2, wherein the pump (38) is an electrically operable pump.
4. The exhaust heat recovery system (10) according to any one of the preceding claims, wherein a cooler (52) for cooling the coolant is arranged in the heat exchange circuit (14).
5. A hybrid vehicle, comprising an exhaust heat recovery system (10) according to any one of the preceding claims.