Engine heat recovery system, engine and vehicle
By introducing exhaust gas return branch and heat exchanger into the engine exhaust system, the cooling liquid is heated by using high-temperature exhaust gas to solve the problem of insufficient heat recovery in the cold machine state, and the rapid heating of the coolant and rapid warm-up of the engine are achieved.
Patent Information
- Application Number
- CN202422261387.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-09-14
AI Technical Summary
In the prior art, the engine exhaust system fails to effectively recover heat in the cold-frigerated state, resulting in slow cooling fluid circulation and affecting the engine warm-up efficiency.
An engine heat recovery system is designed, including the main exhaust pipe, exhaust gas return branch, heat exchanger and control valve. By introducing high-temperature exhaust gas into the exhaust gas return branch in the cold machine state for heat exchange, the coolant is quickly heated up.
It realizes rapid heating of coolant in the cold-frigerated state, shortens the engine warm-up time and improves the engine starting efficiency.
Smart Images
Figure CN223136240U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of engines, and particularly relates to an engine heat recovery system, an engine and a vehicle. Background Art
[0002] The exhaust system of a hybrid engine consists of an integrated exhaust manifold of a cylinder head, a three-way catalytic converter assembly and an exhaust pipe. The heat content of the engine exhaust gas is very high, and the temperature can reach 800 - 900°C after leaving the combustion chamber. The heat carried away by the exhaust gas accounts for about 25% of the total energy. At present, the engine exhaust system and the cooling system operate as independent systems, and there is no application of heat recovery technology in the cold engine state. Content of the Utility Model
[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the utility model is to provide an engine heat recovery system which can recover heat in the cold engine state.
[0004] Another object of the utility model is to provide an engine.
[0005] Another object of the utility model is to provide a vehicle.
[0006] According to an embodiment of the first aspect of the utility model, the engine heat recovery system includes:
[0007] A main exhaust pipe;
[0008] An exhaust gas reflux branch, one end of which is connected to the main exhaust pipe, and the other end is adapted to be connected to the engine intake pipe. The exhaust gas reflux branch is provided with a heat exchanger for heat exchange between the coolant and the exhaust gas flowing through the exhaust gas reflux branch;
[0009] A connection branch connected between the exhaust gas reflux branch and the main exhaust pipe;
[0010] A second control valve provided on the connection branch or at the connection of the connection branch and the main exhaust pipe for controlling the on-off of the connection branch and the main exhaust pipe.
[0011] In some examples of the utility model, the exhaust gas reflux branch is provided with a first switch valve which is located downstream of the heat exchanger in the exhaust gas flow direction of the exhaust gas reflux branch.
[0012] In some examples of the present utility model, the engine heat recovery system includes a first operating condition and a second operating condition. In the first operating condition, the first switching valve is closed and the second control valve is opened so that the exhaust gas flows from the connecting branch into the main exhaust pipe; in the second operating condition, the first switching valve is opened and the second control valve is closed to prevent the exhaust gas from flowing from the connecting branch into the main exhaust pipe.
[0013] In some examples of the present utility model, the connection position of the connecting branch and the exhaust gas return branch on the exhaust gas return branch is located between the heat exchanger and the first switching valve.
[0014] In some examples of the present utility model, the second control valve is a three-way valve. The three-way valve is arranged at the connection of the connecting branch and the main exhaust pipe. The first port and the second port of the three-way valve are connected to the front end and the rear end of the main exhaust pipe, and the third port of the three-way valve is connected to the connecting branch.
[0015] In some examples of the present utility model, the three-way valve includes a first state and a second state. In the first state, the second port is communicated with the third port and the first port is closed; in the second state, the second port is communicated with the first port and the third port is closed.
[0016] In some examples of the present utility model, the second control valve is a two-way valve, and the two-way valve is arranged on the connecting branch.
[0017] In some examples of the present utility model, an air intake guide plate is arranged at the connection of the exhaust gas return branch and the main exhaust pipe, and an air return guide plate is arranged at the connection of the connecting branch and the main exhaust pipe.
[0018] In some examples of the present utility model, the air intake guide plate and the air return guide plate are semi-circular structures.
[0019] In some examples of the present utility model, the exhaust gas return branch is connected to the main exhaust pipe at a first position of the main exhaust pipe, and the connecting branch is connected to the main exhaust pipe at a second position of the main exhaust pipe. Along the flow direction of the exhaust gas in the main exhaust pipe, the first position is upstream of the second position.
[0020] The engine according to the embodiment of the second aspect of the present utility model includes the engine heat recovery system.
[0021] The vehicle according to the embodiment of the third aspect of the present utility model includes the engine.
[0022] The engine heat recovery system provided by the present utility model can rapidly increase the temperature of the coolant circulation in the cold engine start state, and the coolant entering the engine can achieve rapid warm-up. Description of the Drawings
[0023] The above and / or additional aspects and advantages of the present utility model will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:
[0024] Figure 1 Schematic diagram of the engine heat recovery system according to an embodiment of the present utility model;
[0025] Figure 2 Schematic diagram of the structure of the second control valve according to an embodiment of the present utility model;
[0026] Figure 3 Schematic diagram of the operation of the heat recovery system according to an embodiment of the present utility model;
[0027] Figure 4 Schematic diagram of the shutdown of the heat recovery system according to an embodiment of the present utility model;
[0028] Figure 5 Schematic diagram of the engine heat recovery system according to another embodiment of the present utility model;
[0029] Figure 6 Schematic diagram of the structure of the second control valve according to another embodiment of the present utility model;
[0030] Figure 7 Schematic diagram of the air intake pipe flow deflector according to an embodiment of the present utility model;
[0031] Figure 8 Schematic diagram of the return air pipe flow deflector according to an embodiment of the present utility model.
[0032] Description of the reference numerals:
[0033] 1, main exhaust pipe; 2, exhaust gas reflux branch; 3, heat exchanger; 4, first on-off valve; 5, three-way valve; 6, connecting branch; 7, heat exchanger inlet pipe; 8, heat exchanger outlet pipe; 9, actuator of the three-way valve 5; 10, two-way valve; 11, air intake pipe flow deflector; 12, return air pipe flow deflector. Detailed Embodiments
[0034] The embodiments of the present utility model will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described by referring to the drawings are exemplary and are only used to explain the present utility model and should not be construed as a limitation of the present utility model.
[0035] In combination withFigure 1 As shown, the engine heat recovery system according to the first aspect embodiment of the present utility model mainly includes: a main exhaust gas pipeline 1, an exhaust gas recirculation branch 2, a connection branch 6, and a second control valve 5. One end of the exhaust gas recirculation branch 2 is connected to the main exhaust gas pipeline 1, and the other end is adapted to be connected to the engine intake pipeline. The exhaust gas recirculation branch 2 is provided with a heat exchanger 3, and the heat exchanger 3 is used for heat exchange between the coolant and the exhaust gas flowing through the exhaust gas recirculation branch 2. Specifically, the intake end of the exhaust gas recirculation branch 2 is connected to the main exhaust gas pipeline 1, and the outlet end is adapted to be connected to the engine intake pipeline. When exhaust gas recirculation is carried out, the high-temperature exhaust gas will enter the exhaust gas recirculation branch 2 from the main exhaust gas pipeline 1, and then flow into the engine intake pipeline through the exhaust gas recirculation branch 2. When the high-temperature exhaust gas flows through the exhaust gas recirculation branch 2, the coolant in the heat exchanger 3 on the exhaust gas recirculation branch 2 will exchange heat with the high-temperature exhaust gas, thereby realizing the temperature rise of the coolant.
[0036] In addition, the heat exchanger 3 is provided with a heat exchanger inlet water pipe 7 and a heat exchanger outlet water pipe 8. When the high-temperature exhaust gas flows through the exhaust gas recirculation branch 2, it will pass through the heat exchanger 3. At this time, the coolant circulation system will discharge the coolant from the heat exchanger inlet water pipe 7, and the coolant will exchange heat with the passing high-temperature exhaust gas, and the heated coolant will be discharged from the heat exchanger outlet water pipe 8. The discharged high-temperature coolant enters the thermal management system, which can quickly raise the temperature of the engine waterway, heater core, radiator, battery pack, etc. connected to the coolant circulation system, and reach the optimal working temperature faster.
[0037] Furthermore, the connection branch 6 is connected between the exhaust gas recirculation branch 2 and the main exhaust gas pipeline 1. Specifically, the intake port of the connection branch 6 is connected to the exhaust gas recirculation branch 2, and the outlet port of the connection branch 6 is connected to the main exhaust gas pipeline 1. Among them, in the exhaust gas flow direction of the main exhaust gas pipeline 1, the intake port of the exhaust gas recirculation branch 2 on the main exhaust gas pipeline 1 is located upstream of the main exhaust gas pipeline 1, and the outlet port of the connection branch 6 on the main exhaust gas pipeline 1 is located downstream of the main exhaust gas pipeline 1.
[0038] Furthermore, the second control valve is arranged on the connection branch 6 or at the connection between the connection branch 6 and the main exhaust gas pipeline 1, and the second control valve is used to control the on-off of the connection path between the connection branch 6 and the main exhaust gas pipeline 1. Specifically, the second control valve can be arranged on the connection branch 6 or at the connection between the connection branch 6 and the main exhaust gas pipeline 1. When the second control valve is in the open state, the high-temperature exhaust gas can flow through the connection branch 6 and then flow into the main exhaust gas pipeline 1; when the second control valve is in the closed state, the high-temperature exhaust gas cannot flow through the connection branch 6 and then flow into the main exhaust gas pipeline 1.
[0039] According to an embodiment of the present utility model, when the second control valve is opened, it is possible to achieve that the exhaust gas enters from the exhaust gas return branch 2, flows through the connecting branch 6, and finally flows into the main exhaust pipe 1, so as to realize heat recovery in the heat exchanger. Specifically, when the second control valve is opened, the high-temperature exhaust gas will enter from the exhaust gas return branch 2, then flow through the connecting branch 6, and finally flow into the main exhaust pipe 1. When the high-temperature exhaust gas passes through the exhaust gas return branch 2, it will exchange heat with the heat exchanger 3, heating up the coolant inside the heat exchanger 3. The heated coolant will be discharged to the thermal management system, which can quickly heat up the engine waterway, heater core, radiator, battery pack, etc. connected to the coolant circulation system, and reach the optimal working temperature faster.
[0040] Further, the exhaust gas return branch 2 is provided with a first switching valve 4. In the exhaust gas flow direction of the exhaust gas return branch 2, the first switching valve 4 is located downstream of the heat exchanger 3. Specifically, in the exhaust gas flow direction of the exhaust gas return branch 2, the heat exchanger 3 is arranged first, and then the first switching valve 4 is arranged. The first switching valve 4 is downstream of the heat exchanger 3.
[0041] Further, the engine heat recovery system includes a first working condition and a second working condition. In the first working condition, the first switching valve 4 is closed and the second control valve is opened, so that the exhaust gas flows into the main exhaust pipe 1 from the connecting branch 6; in the second working condition, the first switching valve 4 is opened and the second control valve is closed to prevent the exhaust gas from flowing into the main exhaust pipe 1 from the connecting branch 6. Specifically, the engine heat recovery system can have multiple working conditions, including but not limited to the first working condition and the second working condition. When the engine heat recovery system is in the first working condition, the first switching valve 4 is closed and the second control valve is opened. The high-temperature exhaust gas will enter from the exhaust gas return branch 2, then flow through the connecting branch 6, and finally flow into the main exhaust pipe 1. In this case, the exhaust gas cannot flow from the exhaust gas return branch 2 to the engine intake end; when the engine heat recovery system is in the second working condition, the first switching valve 4 is opened and the second control valve is closed. The high-temperature exhaust gas will enter from the exhaust gas return branch 2 and then flow to the engine intake end. In this case, the exhaust gas cannot flow into the main exhaust pipe 1 from the connecting branch 6.
[0042] According to an embodiment of the present utility model, the first operating condition is the low-temperature operating condition of the engine coolant temperature, such as the temperature -40°C ≤ T < 95°C, which can also be referred to as the cold engine state; the second operating condition is the normal operating condition of the engine coolant temperature, such as the temperature T ≥ 95°C. When the engine is in the first operating condition, the original heat recovery system (such as the EGR system) does not work, and the first switching valve 4 is in the closed state. At this time, the engine heat recovery system provided by the present utility model needs to work to quickly warm up the engine. At this time, the second control valve is opened, so as to start the engine heat recovery system provided by the present utility model for heat recovery; when the engine coolant temperature rises to the second operating condition, the original heat recovery system starts to work, and the engine heat recovery system provided by the present utility model pauses working, that is, the switching valve 4 is opened, and at the same time the second control valve is closed. Of course, there may also be other operating conditions, such as the first switching valve 4 and the second control valve are both opened, or the first switching valve 4 and the second control valve are both closed.
[0043] Further, the connection position of the connection branch 6 and the exhaust gas recirculation branch 2 on the exhaust gas recirculation branch 2 is located between the heat exchanger 3 and the first switching valve 4. Specifically, the outlet end of the connection branch 6 is connected to the main exhaust pipe 1, and the inlet end of the connection branch 6 is connected to the exhaust gas recirculation branch 2, and the specific position is any position between the heat exchanger 3 and the first switching valve 4. According to the flow direction of the high-temperature exhaust gas on the exhaust gas recirculation branch 2, the heat exchanger 3, the inlet of the connection branch 6 on the exhaust gas recirculation branch 2, and the first switching valve 4 are sequentially arranged on the exhaust gas recirculation branch 2.
[0044] Combined Figure 1 and Figure 2 As shown, the second control valve is a three-way valve 5. The three-way valve 5 is arranged at the connection of the connection branch 6 and the main exhaust pipe 1. The first port and the second port of the three-way valve 5 are connected to the front end and the rear end of the main exhaust pipe 1, and the third port of the three-way valve 5 is connected to the connection branch 6. Specifically, it can be understood that this is a solution of the present utility model. The second control valve adopts a three-way valve 5 with a three-way structure and is arranged at the connection of the connection branch 6 and the main exhaust pipe 1. The first port and the second port of the three-way valve 5 can also be understood as the front port and the rear port of the main path of the three-way valve 5, which are respectively connected to the front end and the rear end of the main exhaust pipe 1; the third port of the three-way valve 5 can also be understood as the branch port of the three-way valve 5 and is connected to the connection branch 6. At this time, in the flow direction of the exhaust gas on the main exhaust pipe 1, the inlet of the exhaust gas recirculation branch 2 is upstream of the main exhaust pipe 1, and the second control valve, that is, the three-way valve 5, is downstream of the main exhaust pipe 1. More specifically, it can be understood that in the flow direction of the exhaust gas on the main exhaust pipe 1, from upstream to downstream, the inlet of the exhaust gas recirculation branch 2, the first port of the three-way valve 5, and the second port of the three-way valve 5 are sequentially arranged.
[0045] According to an embodiment of the present utility model, the actuator 9 of the three-way valve 5 is a flap adjustment. The disc-shaped opening and closing member rotates around the valve shaft, and the adjustment angle is 90°, which is used to control the opening and closing of the first port and the third port of the three-way valve 5. The actuator 9 can be controlled in multiple states. For example, the first port of the three-way valve 5 is completely closed and the third port is opened; the first port of the three-way valve 5 is opened and the third port is completely closed; of course, it can also be adjusted with the flap of the actuator 9, and both the first port and the third port of the three-way valve 5 are opened, and the specific adjustment angle is not limited.
[0046] Combined Figure 3 with Figure 4 As shown, the three-way valve 5 includes a first state and a second state. In the first state, the second port is communicated with the third port, and the first port is closed; in the second state, the second port is communicated with the first port, and the third port is closed. Specifically, the three-way valve 5 can be controlled in at least two states. For example, in the first state, the first port of the three-way valve 5 is completely closed, and at the same time, the third port is opened. More specifically, it can be understood that the front port of the main path of the three-way valve 5 is completely closed, and at the same time, the branch port of the three-way valve 5 is opened. At this time, the second port and the third port of the three-way valve 5 are in a communicating state. Refer to Figure 3 . At this time, the flap of the actuator 9 closes the first port of the three-way valve 5 downward, and at the same time opens the third port of the three-way valve 5. The exhaust gas in the main exhaust pipe 1 cannot pass through the first port of the three-way valve 5, and the exhaust gas will enter from the intake port of the exhaust gas return branch 2 at the front end of the main exhaust pipe 1, then flow through the heat exchanger 3 on the exhaust gas return branch 2, then return to the third port of the three-way valve 5 from the connecting branch 6, and finally flow into the rear end of the main exhaust pipe 1 from the second port of the three-way valve 5; when in the second state, the first port of the three-way valve 5 is opened, and at the same time, the third port of the three-way valve 5 is completely closed. More specifically, it can be understood that the front port of the main path of the three-way valve 5 is opened, and at the same time, the branch port of the three-way valve 5 is completely closed. At this time, the second port and the first port of the three-way valve 5 are in a communicating state. Refer to Figure 4 . At this time, the flap of the actuator 9 closes the third port of the three-way valve 5 upward, and at the same time opens the first port of the three-way valve 5. The exhaust gas in the connecting branch 6 cannot pass through, and all the exhaust gas passes through the main exhaust pipe 1, flows from the second port of the three-way valve 5 to the first port, and finally flows into the rear end of the main exhaust pipe 1.
[0047] According to an embodiment of the present utility model, when the engine is in the cold start condition, the original heat recovery system does not work and the first switching valve 4 is in the closed state. At this time, the engine heat recovery system provided by the present utility model is required to work to quickly warm up the engine. The actuator 9 of the three-way valve 5 turns downwards to close the first port of the three-way valve 5 and simultaneously open the third port of the three-way valve 5. At this time, the exhaust gas that originally passed through the first port of the three-way valve 5 is blocked by the flap of the valve actuator 9, and all the high-temperature exhaust gas at the front end of the main exhaust pipe 1 is introduced into the exhaust gas return branch 2, then sequentially passes through the heat exchanger 3, the connecting branch 6, and the third port of the three-way valve 5, and finally flows into the rear end of the main exhaust pipe 1 from the second port of the three-way valve 5, forming an exhaust gas loop of the heat recovery system. The coolant of the thermal management system enters the heat exchanger 3 from the heat exchanger inlet pipe 7, exchanges heat with the passing high-temperature exhaust gas, and the heated coolant is discharged from the heat exchanger outlet pipe 8 into the thermal management system. The coolant in the cold start state is at a low temperature, and the high-temperature exhaust gas for heat recovery exchanges heat in the heat exchanger, causing the coolant temperature to rise rapidly, achieving the effect of heat recovery.
[0048] Combined with Figure 5 and Figure 6 As shown, the second control valve is a two-way valve 10, and the two-way valve 10 is arranged on the connecting branch 6. Specifically, it can be understood that this is another solution of the present utility model. The two-way valve 10 adopts a butterfly valve structure. A butterfly valve is a flap regulating valve, and the disc-shaped closing member rotates around the valve shaft and reciprocates about 90° to regulate the opening and closing of the gas path. The two-way valve 10 is directly connected to the connecting branch 6 to control the on-off of the connecting branch 6.
[0049] According to another embodiment of the present utility model, when the engine is in the cold start condition, the original heat recovery system does not work and the first switching valve 4 is in the closed state. At this time, the engine heat recovery system provided by the present utility model is required to work to quickly warm up the engine. The two-way valve 10 is opened, and a part of the high-temperature exhaust gas at the front end of the main exhaust pipe 1 is introduced into the exhaust gas return branch 2, flows through the heat exchanger 3, and then passes through the connecting branch 6. Since the two-way valve 10 on the connecting branch 6 is opened, the high-temperature exhaust gas can flow from the connecting branch 6 into the rear end of the main exhaust pipe 1, forming a high-temperature exhaust gas loop of the heat recovery system. The coolant of the thermal management system enters the heat exchanger 3 from the heat exchanger inlet pipe 7, exchanges heat with the passing high-temperature exhaust gas, and the heated coolant is discharged from the heat exchanger outlet pipe 8 into the thermal management system. The coolant in the cold start state is at a low temperature, and the high-temperature exhaust gas for heat recovery exchanges heat in the heat exchanger, causing the coolant temperature to rise rapidly, achieving the effect of heat recovery.
[0050] Combined with Figure 7 and Figure 8As shown in the figure, an air intake guide plate 11 is provided at the connection between the exhaust gas recirculation branch 2 and the main exhaust pipe 1, and a gas return guide plate 12 is provided at the connection between the connection branch 6 and the main exhaust pipe 1. Specifically, an air intake guide plate 11 is provided at the air inlet of the exhaust gas recirculation branch 2 and the main exhaust pipe 1. When the exhaust gas in the main exhaust pipe 1 flows and encounters the air intake guide plate 11, a flow split is formed, and more exhaust gas can be introduced into the exhaust gas recirculation branch 2 through the air intake guide plate 11; a gas return guide plate 12 is provided at the air outlet of the connection branch 6 and the main exhaust pipe 1. The air flow direction of the main path exhaust gas in the main exhaust pipe 1 is from top to bottom. According to Bernoulli's principle, the greater the flow velocity, the smaller the pressure. The exhaust gas flow velocity in the main exhaust pipe 1 is large, and the exhaust gas flow velocity in the connection branch 6 is small. Due to the existence of the flow velocity difference, the air flow in the main exhaust pipe 1 can effectively attract the air flow in the connection branch 6. The added gas return guide plate 12 can strengthen the Bernoulli effect and increase the air flow in the heat recovery system.
[0051] Furthermore, the air intake guide plate 11 and the gas return guide plate 12 are semi-circular structures. Specifically, the air intake pipe guide plate 11 and the gas return pipe guide plate 12 are semi-circular structures. According to needs, guide plate structures with different radii and heights can be designed to match the required exhaust gas recovery amount of the system.
[0052] Furthermore, the exhaust gas recirculation branch 2 is connected to the main exhaust pipe 1 at a first position of the main exhaust pipe 1, and the connection branch 6 is connected to the main exhaust pipe 1 at a second position of the main exhaust pipe 1. Along the flow direction of the exhaust gas in the main exhaust pipe 1, the first position is upstream of the second position. Specifically, the air inlet of the exhaust gas recirculation branch 2 is provided at the first position on the main exhaust pipe 1, and the air outlet of the connection branch 6 is provided at the second position on the main exhaust pipe 1. Along the flow direction of the exhaust gas in the main exhaust pipe 1, the air inlet of the exhaust gas recirculation branch 2 is upstream, and the air outlet of the connection branch 6 is downstream.
[0053] The engine according to the second aspect embodiment of the present invention includes the above-mentioned engine heat recovery system.
[0054] The vehicle according to the third aspect embodiment of the present invention includes the above-mentioned engine.
[0055] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "front end", "rear end", "inlet", "outlet", "upstream", "downstream", etc. is the orientation or positional relationship based on the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.
[0056] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "embodiment", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.
[0057] Although the embodiments of the present utility model have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present utility model, and the scope of the present utility model is defined by the claims and their equivalents.
Claims
1. An engine heat recovery system, characterized in that, Comprising: A main exhaust gas pipeline; An exhaust gas recirculation branch, one end of the exhaust gas recirculation branch is connected to the main exhaust gas pipeline, and the other end is adapted to be connected to an engine intake pipeline. The exhaust gas recirculation branch is provided with a heat exchanger, and the heat exchanger is used for heat exchange between the coolant and the exhaust gas flowing through the exhaust gas recirculation branch; A connecting branch (6), the connecting branch (6) is connected between the exhaust gas recirculation branch and the main exhaust gas pipeline; A second control valve, the second control valve is arranged on the connecting branch (6) or at the connection between the connecting branch (6) and the main exhaust gas pipeline, and the second control valve is used to control the on-off of the connecting branch (6) and the main exhaust gas pipeline.
2. The engine heat recovery system according to claim 1, wherein The exhaust gas recirculation branch is provided with a first on-off valve (4), and in the exhaust gas flow direction of the exhaust gas recirculation branch, the first on-off valve (4) is located downstream of the heat exchanger.
3. The engine heat recovery system according to claim 2, wherein, The engine heat recovery system includes a first operating condition and a second operating condition, In the first operating condition, the first on-off valve (4) is closed, and the second control valve is opened, so that the exhaust gas flows from the connecting branch (6) into the main exhaust gas pipeline; In the second operating condition, the first on-off valve (4) is opened, and the second control valve is closed, to prevent the exhaust gas from flowing from the connecting branch (6) into the main exhaust gas pipeline.
4. The engine heat recovery system according to claim 2, wherein The connection position of the connecting branch (6) and the exhaust gas recirculation branch on the exhaust gas recirculation branch is located between the heat exchanger and the first on-off valve (4).
5. The engine heat recovery system according to claim 1, wherein The second control valve is a three-way valve, the three-way valve is arranged at the connection between the connecting branch (6) and the main exhaust gas pipeline, a first port and a second port of the three-way valve are connected to the front end and the rear end of the main exhaust gas pipeline, and a third port of the three-way valve is connected to the connecting branch (6).
6. The engine heat recovery system according to claim 5, characterized in that, The three-way valve includes a first state and a second state, In the first state, the second port is communicated with the third port, and the first port is closed; In the second state, the second port is communicated with the first port, and the third port is closed.
7. The engine heat recovery system according to claim 1, characterized in that The second control valve is a two-way valve, and the two-way valve is arranged on the connecting branch (6).
8. The engine heat recovery system according to claim 7, characterized in that An air intake guide plate is arranged at the connection between the exhaust gas recirculation branch and the main exhaust gas pipeline, and a return air guide plate is arranged at the connection between the connecting branch (6) and the main exhaust gas pipeline.
9. The engine heat recovery system according to claim 8, wherein The air intake guide plate and the return air guide plate are semi-circular structures.
10. The engine heat recovery system according to claim 1, characterized in that, The exhaust gas recirculation branch is connected to the main exhaust gas pipeline at a first position of the main exhaust gas pipeline, the connecting branch (6) is connected to the main exhaust gas pipeline at a second position of the main exhaust gas pipeline, and along the exhaust gas flow direction in the main exhaust gas pipeline, the first position is upstream of the second position.
11. An engine, characterized in that, Including the engine heat recovery system according to any one of claims 1 to 10.
12. A vehicle, characterized in that, Including the engine according to claim 11.