Engine waste heat utilization device

Abstract

The application belongs to the technical field of engines and relates to an engine waste heat utilization device which comprises a cylinder, a radiator and a heat absorber, the cylinder is internally provided with a compression chamber and an expansion chamber, the radiator and the heat absorber are connected with the compression chamber and the expansion chamber respectively, further comprising an ejector for driving the working medium to reciprocatingly flow between the expansion chamber and the compression chamber; further comprising a bypass pipe connected in parallel with the heat absorber, a switching valve is arranged to switch the flow path of the working medium through the heat absorber or the bypass pipe when the working medium returns to the expansion chamber, the compression chamber is provided with a one-way liquid inlet valve and an outlet valve, and the compression chamber has liquid therein; the working medium flowing into the expansion chamber is controlled to flow through the heat absorber, and the working medium flowing out of the expansion chamber is controlled to flow through the bypass pipe. The application solves the problems of large volume, low conversion efficiency, poor dynamic adaptability and high cost of the existing waste heat recovery system, realizes efficient heat exchange and energy transmission of the working medium through the cooperative control of the compression chamber and the expansion chamber circulation design and the bypass pipe and the switching valve, and improves the waste heat utilization rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engines, and in particular, relates to an engine waste heat utilization device. BACKGROUND

[0002] In the field of modern commercial vehicles and engineering machinery, the engine is the core component that provides power. Its main working principle is to generate heat energy through fuel combustion and convert part of the heat energy into mechanical energy to drive the vehicle or equipment. However, the thermal efficiency of existing internal combustion engines is limited by many factors. On the test bench, it can usually reach a maximum of about 50% thermal efficiency, but under actual operating conditions, affected by load fluctuations, environmental conditions, and transmission systems, its thermal efficiency is usually only 20%-30%.

[0003] During the combustion process, the chemical energy of the fuel is mainly consumed in the form of mechanical energy, cooling loss, and exhaust loss. Among them, the exhaust gas temperature of the engine is usually as high as 200-400℃, accounting for 30%-40% of the total energy of the fuel. The heat energy carried by these exhaust gases is usually directly discharged to the environment, not only causing a large amount of energy waste, but also increasing the fuel consumption and emission pollution of the vehicle.

[0004] In order to improve the thermal efficiency of the engine and reduce fuel consumption, the existing technology proposes various waste heat recovery schemes, such as:

[0005] 1. Waste heat boiler: Some commercial vehicles and ship engines use waste heat boilers to introduce high-temperature exhaust gas into a heat exchanger, which absorbs heat through water or oil medium, and then is used for heating or auxiliary power system. However, this system is complex in structure, requires a large installation space, and is not suitable for small and medium-sized vehicles.

[0006] 2. Secondary utilization of turbocharger: In some high-performance vehicles, an additional turbo expander is added to recover the kinetic energy of the exhaust gas and convert it into mechanical work or electrical energy. However, this scheme has low efficiency under low load conditions, and the additional mechanical structure increases the complexity and maintenance cost of the system.

[0007] 3. Rankine cycle (ORC) system: Organic working medium (such as R245fa, R134a, etc.) is used to exchange heat through phase change, converting exhaust gas heat energy into power output. Although this system has been applied in some industrial fields, its application on vehicles is limited by factors such as equipment size, condensation heat dissipation, and economic cost.

[0008] In addition, CN103470352A discloses an automobile exhaust waste heat recovery device based on a Stirling engine, which uses the Stirling cycle principle to convert exhaust waste heat into mechanical energy. However, this device still has the following problems in actual application:

[0009] 1. Complex structure and large space occupation: Stirling engine outputs electric energy, which requires a complex system.

[0010] 2. Poor performance: Stirling engine heat exchanger is approximately isothermal, while the exhaust waste heat is a variable temperature heat source, so the energy recovery is low.

[0011] 3. High manufacturing and maintenance cost: Due to the high requirements of Stirling engine on material and machining precision, the manufacturing cost is high, and the maintenance and repair are complex, which is not conducive to large-scale popularization and application.

[0012] In summary, the existing waste heat recovery technical solutions still have problems such as low energy conversion efficiency, large equipment size, high cost and poor performance in vehicle application, which limits its wide application. Therefore, how to develop a more compact, efficient and low-cost waste heat recovery system to further improve the heat utilization efficiency of the engine and reduce fuel consumption is an important problem to be solved by the technical personnel in the field. SUMMARY

[0013] To solve the above problems, the present application provides an engine waste heat utilization device, which solves the problems of low energy conversion efficiency, large equipment size and high cost of the existing waste heat recovery technology in vehicle application. Through the circulation design of compression chamber and expansion chamber and the cooperation of bypass pipeline and switching valve, efficient heat exchange and energy transfer of working medium are realized, and the output power is directly provided to the cooling water flow path or oil supply flow path of the engine, avoiding the problems of large size and high cost caused by crankshaft and motor.

[0014] The present application provides an engine waste heat utilization device, comprising a cylinder, a radiator, a heat absorber, an exhaust, a bypass pipe and a switching valve;

[0015] The cylinder is internally provided with a compression chamber and an expansion chamber, and the exhaust is arranged in the cylinder for driving the working medium to reciprocate between the compression chamber and the expansion chamber;

[0016] The heat absorber is arranged in parallel with the bypass pipe;

[0017] The switching valve is arranged between the expansion chamber and the heat absorber and the bypass pipe, for selectively controlling the working medium to flow through the heat absorber or the bypass pipe;

[0018] The radiator has a first end and a second end, the first end of which is in fluid communication with the compression chamber, and the second end is directly connected with the bypass pipe, and the working medium enters the bypass pipe from the expansion chamber;

[0019] The heat absorber has a first end and a second end, the first end of which is in fluid communication with the compression chamber, and the second end is in fluid communication with the expansion chamber, and the working medium enters the expansion chamber from the heat absorber;

[0020] The bypass pipe comprises a first end and a second end, the first end of which is in fluid communication with the expansion chamber, and the second end of which is in fluid communication with the compression chamber.

[0021] The compression chamber has liquid therein, and comprises a liquid inlet valve and a liquid outlet valve, both of which are one-way valves.

[0022] In a preferred implementation, further comprising an exhaust heat exchanger, which is arranged at the exhaust emission side of the engine, and the heat of the exhaust is transferred to the heat sink through a heat transfer medium.

[0023] In a preferred implementation, further, the liquid inlet valve of the compression chamber is in communication with the oil sump of the engine, so as to receive and guide the engine oil from the oil sump to flow into the compression chamber. The liquid outlet valve of the compression chamber is in fluid communication with the oil supply pipeline of the engine, so as to control the liquid in the compression chamber to be delivered to the oil supply pipeline.

[0024] In a preferred implementation, further, the heat sink and the exhaust heat exchanger are both provided with a liquid inlet and a liquid outlet, and the heat sink and the exhaust heat exchanger are in liquid heat exchange; the liquid outlet of the heat sink is connected to the liquid inlet valve of the compression chamber through a fluid passage, and the liquid inlet of the exhaust heat exchanger is connected to the liquid outlet valve of the compression chamber through a fluid passage.

[0025] In a preferred implementation, further, comprising a bypass valve, which is configured to have at least three fluid interfaces for adjusting the distribution ratio of the liquid among different circuits, wherein:

[0026] The first fluid interface of the bypass valve is in fluid communication with the liquid inlet valve or the liquid outlet valve of the compression chamber, so as to control the liquid flow path into or out of the compression chamber;

[0027] The second fluid interface of the bypass valve is in fluid communication with the liquid inlet of the exhaust heat exchanger, so as to guide the liquid into the exhaust heat exchanger for heat exchange;

[0028] The third fluid interface of the bypass valve is in fluid communication with the oil supply pipeline of the engine or the oil circuit of the oil sump of the engine, so as to control the liquid to enter the engine lubrication system or return to the oil sump;

[0029] The bypass valve is further configured to dynamically adjust the flow ratio of the liquid through the second fluid interface and the third fluid interface.

[0030] In a preferred implementation, further, the heat sink adopts a variable-temperature heat absorption structure. The temperature difference between the liquid temperature at the liquid outlet end of the exhaust heat exchanger and the liquid temperature at the liquid inlet end thereof is ≥ 150℃.

[0031] In a preferred implementation, further, comprising a heat exchanger, wherein the heat exchanger is configured with two independent fluid passages, i.e. a first flow path and a second flow path, for heat exchange and circulation of the liquid.

[0032] In the preferred implementation, further, the first flow path is communicated between the liquid outlet of the heat sink and the liquid inlet valve of the compression chamber, for delivering the heat energy released from the heat sink to the compression chamber to preheat the liquid inside the compression chamber;

[0033] The second flow path is communicated between the liquid outlet valve of the compression chamber and the liquid inlet of the exhaust heat exchanger, for guiding the liquid discharged from the compression chamber into the exhaust heat exchanger to exchange heat with the exhaust waste heat.

[0034] In the preferred implementation, further, a diaphragm is arranged in the compression chamber, for forming the first fluid chamber and the second fluid chamber in the compression chamber;

[0035] The first fluid chamber is used for containing the liquid, and the fluid is allowed to enter and exit through the liquid inlet valve and the liquid outlet valve;

[0036] The second fluid chamber is used for containing the working medium, and is communicated with the expansion chamber through the pipeline, so as to realize the circulating flow of the working medium between the expansion chamber and the compression chamber.

[0037] In the preferred implementation, further, a hydraulic motor is arranged, which is fluidly communicated with the liquid outlet valve through the pipeline, and is fluidly communicated with the liquid inlet valve through the pipeline;

[0038] Further, an engine cooling water pump is arranged, and the hydraulic motor is mechanically connected with the engine cooling water pump, for driving the engine cooling water pump to operate by using the hydraulic energy generated by the liquid flow;

[0039] And / or, an electric motor is arranged, which is power-connected with the ejector, for driving the ejector to reciprocate in the cylinder.

[0040] The beneficial effects of the present application are:

[0041] First, the engine waste heat utilization device of the application realizes the precise heat exchange between the heat absorption of the working medium and the exhaust waste heat by setting compression chamber and expansion chamber in the cylinder and driving the working medium to reciprocate between the two by the ejector, improves the waste heat recovery efficiency. And the pressure potential generated by the working medium after absorbing heat is transmitted to the cooling water flow path or oil supply flow path of the engine through the liquid, realizing the direct utilization of potential energy and further improving the engine performance. In addition, the problem of large volume and high cost caused by the structure of recovering energy through the crankshaft and motor is avoided. Compared with the existing waste heat boiler and ORC system, the design effectively improves the waste heat recovery efficiency and the structure is more compact, which is convenient for integration into the limited space of the vehicle power system. Through the design of bypass pipe and the regulation of switching valve, the working medium can accurately exchange heat between the heat absorber and the external heat source, thereby reducing heat exchange loss and improving heat exchange efficiency. In addition, by setting liquid in the compression chamber and equipping liquid inlet valve and liquid outlet valve, the pressure potential generated by the working medium after absorbing heat can be transmitted to the cooling water flow path or oil supply flow path of the engine through the liquid, realizing the direct utilization of potential energy and further improving the engine performance. Compared with the prior art, the application greatly reduces energy loss, improves the waste heat utilization rate of the engine, and reduces additional energy consumption, making the system more economical. Compared with traditional schemes such as Rankine cycle system and Stirling engine, the device structure of the application is more simplified, which reduces the dependence on high-precision manufacturing and special materials, reduces the manufacturing cost and maintenance complexity, and is more suitable for large-scale popularization and application.

[0042] Second, in the preferred implementation mode, the application sets an exhaust heat exchanger between the engine exhaust emission side and the heat absorber, so that the high-temperature exhaust gas emitted by the engine can be effectively recovered and transmitted to the heat absorber for heat exchange with the working medium, thereby improving the waste heat utilization efficiency.

[0043] Third, in the preferred implementation mode, the application realizes the direct introduction of oil by making the liquid inlet valve of the compression chamber communicate with the oil pan of the engine, and makes the working medium absorb heat and generate pressure potential directly transmitted to the oil by making the liquid outlet valve communicate with the engine oil supply pipeline, thereby eliminating the energy conversion loss of other energy conversion methods.

[0044] Fourth, in the preferred implementation mode, the application sets a bypass valve to dynamically adjust the flow distribution of the liquid between different circuits according to system requirements, thereby optimizing the waste heat utilization efficiency. The multi-fluid interface design of the bypass valve enables flexible control of the flow path of the liquid between the compression chamber, the exhaust heat exchanger and the engine lubrication system. When the system needs to improve the heat exchange efficiency, the liquid can be preferentially introduced into the exhaust heat exchanger for waste heat recovery, thereby increasing the liquid temperature and improving the heat exchange effect; when the engine lubrication demand increases, the bypass valve can adjust the liquid flow to the oil supply pipeline to ensure stable oil supply and reduce the dependence on additional heat source.

[0045] Fifth, in the preferred implementation, the heat sink of the application adopts the variable temperature heat absorption structure, which reduces the heat exchange loss between the working medium and the heat source and improves the efficiency of heat transfer. At the same time, the temperature difference between the outlet liquid temperature and the inlet liquid temperature of the tail gas heat exchanger is ≥ 150℃, which ensures that the waste heat of the tail gas can be fully recovered, improves the heat utilization rate of the heat exchanger, and reduces the waste heat loss.

[0046] Sixth, in the preferred implementation, the application sets up a heat exchanger to make the liquid in different circuits for efficient heat exchange and circulation, thereby improving the heat recovery rate, reducing energy waste, and optimizing the overall performance of the engine waste heat utilization system.

[0047] Seventh, in the preferred implementation, the diaphragm arranged in the compression chamber of the application can effectively isolate the liquid and the working medium, forming independent first and second fluid chambers, so that the liquid and the working medium flow in their respective independent flow channels, avoiding the influence of the liquid on the heat exchange performance of the heat exchanger, and also eliminating the problem of working medium leakage through the liquid.

[0048] Eighth, in the preferred implementation, the application sets up a hydraulic motor and an engine cooling water pump mechanical transmission connection, so that the hydraulic motor can directly drive the engine cooling water pump to operate by using the hydraulic energy generated during the liquid flow, thereby realizing the driving of the cooling system without additional energy input, improving the energy utilization efficiency. At the same time, the introduction of the hydraulic motor can reduce the dependence on engine mechanical energy and reduce the engine load. In addition, the driving mode of the ejector can be selected to be powered by an electric motor, so that the ejector can perform stable reciprocating motion in the cylinder. This structure not only optimizes the power transmission mode of the waste heat utilization system, but also simplifies the mechanical transmission structure. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a structural schematic diagram of the engine waste heat utilization device of embodiment 1 of the application;

[0050] Figure 2 is a structural schematic diagram of the engine waste heat utilization device of embodiment 2 of the application installed with a heat exchanger;

[0051] Figure 3 is a structural schematic diagram of the engine waste heat utilization device of embodiment 3 of the application installed with a hydraulic motor and a cooling water pump;

[0052] Figure 4 is a structural schematic diagram of the compression chamber of the engine waste heat utilization device of embodiment 3 of the application installed with a diaphragm.

[0053] Wherein, 1-cylinder; 2-compression chamber; 3-radiator; 4-discharger; 5-heat absorber; 6-switching valve; 7-expansion chamber; 8-tail gas heat exchanger; 9-liquid inlet valve; 10-liquid outlet valve; 11-engine; 12-bypass valve; 13-heat exchanger; 14-hydraulic motor; 15-bypass pipe; 16-diaphragm; 17-cooling water pump. DETAILED DESCRIPTION

[0054] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings and examples.

[0055] The up, down, left, right, front and back orientation terms in the present application file are established based on the positional relationship shown in the drawings. Different drawings may change the corresponding positional relationship, so it cannot be understood as a limitation on the scope of protection.

[0056] In the present application, the terms "mounting", "connection", "interface", "connection", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, it can also be detachably connected, it can also be integrally connected, it can also be mechanically connected, it can also be electrically connected or can communicate with each other, it can also be directly connected, it can also be indirectly connected through an intermediate medium, it can be the interconnection of two components, or it can be the interaction relationship of two components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] The present application provides a kind of engine waste heat utilization device, which is a kind of heat engine, and its heat absorption end uses variable temperature heat absorption mode, recovers engine waste heat in the form of sensible heat, to improve heat conversion efficiency.Simultaneously, waste heat utilization device exports high-pressure liquid, without piston, crankshaft and other mechanical structures, reduce volume, weight and manufacturing cost.In addition, the high-pressure liquid exported by the waste heat utilization device can be directly used for engine oil supply flow path, saving oil pump, realizing that pressure potential of waste heat utilization device directly drives oil supply system;It can also be directly exchanged with engine tail gas heat exchanger, without additional liquid pump for tail gas heat exchange.Therefore, the engine waste heat utilization device of the present application has the advantages of compact structure, low cost, excellent performance and small space occupation.

[0058] It should be noted that sensible heat release refers to the heat released by a substance during temperature reduction, but its phase (solid, liquid, gas) does not change.In other words, the characteristic of sensible heat release is that sensible heat release only affects temperature, and the temperature of the substance will decrease when it releases sensible heat, while the substance remains in its original state and does not cause phase change such as melting, solidification, evaporation or condensation.The common forms of sensible heat release include the heat released by a metal block during cooling, the heat released by high-temperature air during cooling in a heat exchanger, and the heat released by hot water during cooling.

[0059] Embodiment 1

[0060] Referring to the drawings Figure 1 An engine waste heat utilization device, which comprises a cylinder 1, an expeller 4 located inside the cylinder 1, a heat sink 3 and a heat absorber 5. The cylinder 1 is provided with a compression chamber 2 and an expansion chamber 7, and a working medium is located in the compression chamber 2 and the expansion chamber 7. The expeller 4 is used to drive the working medium to reciprocate in the compression chamber 2 and the expansion chamber 7. The compression chamber 2 and the expansion chamber 7 of the cylinder 1 are connected by two parallel bypass pipes, one of which is a bypass pipe 15, and the other is provided with the heat sink 3 and the heat absorber 5. Specifically, the gas inlet of the expansion chamber 7 is connected with the gas outlet of the heat absorber 5, so that the working medium heated by the heat absorber 5 enters the expansion chamber 7; the gas outlet of the expansion chamber 7 is connected with the gas inlet of the heat sink 3 through the bypass pipe 15, so that the working medium flows out of the expansion chamber 7 to the heat sink 3 for heat dissipation. A switching valve 6 is arranged between the expansion chamber 7 and the heat absorber 5 and the bypass pipe 15, and the switching valve 6 is used to select whether the working medium flows into the expansion chamber 7 through the heat absorber 5 or flows out of the expansion chamber 7 through the bypass pipe 15 during the reciprocation of the working medium between the compression chamber 2 and the expansion chamber 7 according to the cycle requirement. The gas outlet of the heat sink 3 is connected with the gas inlet of the compression chamber 2, so that the working medium is cooled by the heat sink 3 after completing the expansion in the expansion chamber 7, and then enters the compression chamber 2; the gas inlet of the heat absorber 5 is connected with the gas outlet of the compression chamber 2, so that the working medium heated by the heat absorber 5 after flowing out of the compression chamber 2 enters the expansion chamber 7, and the working medium flowing out of the expansion chamber 7 enters the heat sink 3 for cooling and then returns to the compression chamber 2, so as to realize the circulation flow.

[0061] The compression chamber 2 further comprises a liquid inlet and a liquid outlet, and a liquid inlet valve 9 is connected with the liquid inlet of the compression chamber 2 and the liquid outlet of the heat absorber 5 respectively, and the liquid outlet is connected with a liquid outlet valve 10.

[0062] The liquid only exists in the compression chamber 2, and there is no liquid in the expansion chamber 7, only the working medium (gas). The pressure of the liquid is always balanced with the pressure of the working medium in the compression chamber 2. When the pressure of the working medium rises, the liquid is squeezed out of the compression chamber 2 and flows out through the liquid outlet valve 10; when the pressure of the working medium decreases, the liquid outside flows into the compression chamber 2 through the liquid inlet valve 9. Therefore, the flow of the liquid is driven by the change of the pressure of the working medium in the compression chamber 2, and the expansion chamber 7 is only used for the expansion and flow of the working medium.

[0063] The waste heat utilization device further comprises a motor, which is connected with the expeller 4 in power and is used to drive the expeller 4 to reciprocate in the cylinder 1.

[0064] In the implementation of the present application, the working medium is a gas, preferably helium, nitrogen, argon, air, Co2, etc., and the liquid is oil, water, glycol solution, etc., to adapt to different scenarios of waste heat utilization.

[0065] The working principle of the system is based on gas thermodynamic cycle and liquid pressure balance. Due to the reciprocating movement of the displacer 4 in the cylinder 1, the working medium is driven to circulate between the compression chamber 2 and the expansion chamber 7 through the bypass pipeline, resulting in periodic changes in the temperature and pressure of the working medium in the chamber. The temperature of the working medium entering the expansion chamber is close to the outlet temperature of the heat absorber 5, and the temperature of the working medium entering the compression chamber is close to the outlet temperature of the heat sink 3, so the temperature of the working medium in the compression chamber 2 and the expansion chamber 7 will change, and the working medium will continuously undergo the dynamic process of working medium heat absorption and temperature rise → liquid discharge → working medium temperature drop → liquid replenishment in the system. This process can be described by the ideal gas state equation and the first law of thermodynamics. The behavior of the working medium (gas) conforms to the ideal gas state equation:

[0066] PV = mRT

[0067] Where: P is the pressure of the working medium; V is the volume of the chamber (which changes with the movement of the piston); m is the amount of substance of the working medium (assumed constant); R is the gas constant; T is the temperature of the working medium.

[0068] The pressure and temperature of the working medium in the expansion chamber 7 and the compression chamber 2 are different:

[0069] P2V2 = mRT2

[0070] P7V7 = mRT7

[0071] Where: P2, V2, T2 are the pressure, volume and temperature of the compression chamber 2 respectively; P7, V7, T7 are the pressure, volume and temperature of the expansion chamber 7 respectively.

[0072] Due to the movement of the displacer 4 causing volume changes, ignoring the volume of the heat exchanger and the parallel pipe, the pressure of the working medium is:

[0073]

[0074] Due to the movement of the displacer 4 causing volume changes, it will cause fluctuations in pressure and temperature. The temperature of the working medium in the expansion chamber is higher than that in the compression chamber, resulting in an increase in the overall temperature and pressure of the working medium when the volume of the expansion chamber 7 increases; when the volume of the compression chamber 2 increases, the overall temperature of the working medium decreases and the pressure decreases. The liquid pressure P L is affected by the working medium pressure P2 and follows the Pascal principle P L = P2.

[0075] Specifically, during the process of the working medium flowing from the compression chamber 2 to the expansion chamber 7, it needs to be heated in the heat absorber 5:

[0076] Q in = nC v (T7-T2)

[0077] In the formula: Q in represents the heat absorbed by the working medium in the heat absorber 5; C v is the constant volume specific heat capacity of the gas.

[0078] The high-temperature and high-pressure working medium enters the expansion chamber 7, causing the temperature T7 inside the expansion chamber 7 to rise and the pressure P7 to rise.

[0079] Due to the rise in the working medium pressure of the compression chamber 2, the liquid pressure in the compression chamber 2 rises synchronously P L =P2, and when the liquid pressure P L is higher than the opening pressure of the liquid outlet valve 10, the liquid is squeezed out of the compression chamber 2, that is, P L >P outlet , the liquid outlet valve 10 opens, and the liquid flows out of the compression chamber 2 and into the external pipeline.

[0080] When the displacer 4 moves towards the expansion chamber 7, the volume of the expansion chamber 7 decreases and the volume of the compression chamber 2 increases, causing the pressure to drop, and since P L =P2, the liquid pressure in the compression chamber 2 decreases accordingly. When the liquid pressure P L in the compression chamber 2 is lower than the opening pressure P inlet of the liquid inlet valve 9, that is, P L inlet , external liquid flows into the compression chamber 2 to replenish the liquid.

[0081] When the liquid enters the compression chamber 2, the liquid pressure in the compression chamber 2 gradually rises P L =P2↑, and when the liquid pressure in the compression chamber 2 rises to near equilibrium, that is, P L ≈P inlet , the liquid inlet valve 9 closes to prevent excessive inflow, ensuring that the compression chamber 2 always maintains an appropriate amount of liquid.

[0082] Further, the engine waste heat utilization device further comprises a tail gas heat exchanger 8. The tail gas heat exchanger 8 is in fluid communication with the tail gas exhaust system of the engine 11, the gas inlet end of the tail gas heat exchanger 8 is connected with the tail gas exhaust port of the engine 11, and the gas outlet end of the tail gas heat exchanger 8 is in communication with the exhaust pipeline, so as to ensure that the engine tail gas can smoothly enter the tail gas heat exchanger 8 and exchange heat. The heat exchange side of the tail gas heat exchanger 8 exchanges heat with the heat absorber 5 through a heat transfer medium, so that the high-temperature tail gas discharged by the engine 11 releases heat in the tail gas heat exchanger 8 and exchanges heat with the working medium in the waste heat utilization device through the heat transfer medium, thereby increasing the working medium temperature and improving the waste heat recovery efficiency.

[0083] ​In order to realize compact structure and high efficiency heat exchange, the heat absorber 5 has a liquid inlet and a liquid outlet, and the tail gas heat exchanger 8 also has a liquid inlet and a liquid outlet. The heat absorber 5 and the tail gas heat exchanger 8 are connected through a liquid heat exchange loop to form an independent liquid heat exchange channel. The liquid outlet of the heat absorber 5 is communicated with a liquid inlet valve 9 of the compression chamber 2, which is used to guide the liquid after heat absorption into the compression chamber 2. The liquid inlet of the tail gas heat exchanger 8 is communicated with a liquid outlet valve 10 of the compression chamber 2, which is used to receive the liquid from the compression chamber 2 and heat it by using the waste heat of the tail gas. After the liquid absorbs the waste heat of the tail gas in the tail gas heat exchanger 8, it flows into the heat absorber 5 and transfers heat to the working medium, thereby further increasing the temperature of the working medium. In addition, the flow of the liquid in the tail gas heat exchanger 8 and the heat absorber 5 is driven by the waste heat utilization device itself, without the need for an additional liquid pump, thereby reducing the volume and manufacturing cost of the device. Since the liquid flow directly depends on the potential energy of the liquid in the compression chamber 2, rather than relying on an external power pump, the overall heat exchange efficiency and energy utilization rate of the system are further improved.

[0084] Further, the liquid inlet valve 9 of the compression chamber 2 is communicated with the oil pan oil of the engine 11, and the liquid outlet valve 10 is communicated with the oil supply pipeline of the engine 11, so as to realize the circulation of the oil by using the pressure fluctuation of the working medium. The liquid inlet valve 9 is used to flow the oil from the oil pan of the engine 11 into the compression chamber 2 when the pressure in the compression chamber 2 is lower than the oil pan oil pressure. The liquid outlet valve 10 is used to flow the oil from the compression chamber 2 into the oil supply pipeline of the engine 11 when the pressure in the compression chamber 2 is higher than the oil supply pipeline pressure. During the working process, when the expeller 4 moves towards the compression chamber 2, the volume of the compression chamber 2 decreases, the pressure in the chamber increases, and the oil is pushed to flow out through the liquid outlet valve 10 and enters the oil supply pipeline of the engine 11; when the expeller 4 moves towards the expansion chamber 7, the volume of the compression chamber 2 increases, which causes the pressure in the compression chamber 2 to decrease, so that the oil flows into the compression chamber 2 through the liquid inlet valve 9 under the action of the oil pan pressure, thereby realizing the circulation of the oil. Through the above structure, the function of the oil pump is realized by the reciprocating motion of the expeller 4, the oil is transported by using the natural fluctuation of the working medium pressure, the need for an independent oil pump is reduced, the direct utilization of the potential energy of the liquid in the waste heat utilization device is realized, the energy efficiency of the system is improved, and the installation demand for additional power equipment is reduced, thereby optimizing the structural design of the engine oil system.

[0085] Further, the engine waste heat utilization device further comprises a bypass valve 12, which has a first port, a second port and a third port, for adjusting the flow distribution of the liquid between the exhaust heat exchanger 8 and the engine 11 oil supply pipeline or oil sump oil circuit, to optimize the liquid flow path of the waste heat utilization device, reduce flow loss and improve system efficiency. Specifically, the first port is in communication with the liquid inlet valve 9 or the liquid outlet valve 10 of the compression chamber 2, so that the liquid in the compression chamber 2 can enter the external circuit through the bypass valve 12. The second port is in communication with the liquid inlet of the exhaust heat exchanger 8, so that the liquid can be heat exchanged through the exhaust heat exchanger 8, improving the heat energy recovery efficiency. The third port is in communication with the oil supply pipeline or oil sump oil circuit of the engine 11, so that part of the liquid can directly enter the lubrication system of the engine 11, reducing the additional pipeline loss.

[0086] The bypass valve 12 can adjust the flow ratio between the second port and the third port, specifically including: when the waste heat utilization demand is higher, the bypass valve 12 increases the flow of the second port, so that more liquid flows into the exhaust heat exchanger 8, improving the waste heat recovery capacity. When the engine lubrication demand increases or the heat exchange demand decreases, the bypass valve 12 increases the flow of the third port, so that more liquid flows to the oil supply pipeline or oil sump of the engine 11, to optimize the lubrication effect and reduce the liquid flow resistance. When the system operating condition changes, the bypass valve 12 can dynamically adjust the liquid flow distribution to achieve an optimal balance between waste heat recovery and engine lubrication, improving the overall efficiency of the system.

[0087] The bypass valve 12 can dynamically adjust the flow distribution of the liquid between the second port (exhaust heat exchanger 8) and the third port (engine oil circuit) according to the system operating condition and external control signal, specifically including dynamic adjustment through temperature sensor, flow demand feedback through pressure sensor, and precise adjustment through electric control valve. The temperature sensor T1 is arranged in the liquid inlet pipeline of the exhaust heat exchanger 8, when the exhaust gas temperature is detected to be high and the heat exchange demand increases, the bypass valve 12 increases the flow of the second port, so that more liquid flows to the exhaust heat exchanger 8, improving the heat exchange capacity. When the exhaust gas temperature is low or the heat exchanger heat exchange capacity is saturated, the bypass valve 12 reduces the flow of the second port, reducing the proportion of liquid flowing through the exhaust heat exchanger. The temperature sensor T2 is arranged in the engine 11 oil circuit, when the oil temperature is too high and the lubrication system cooling demand increases, the bypass valve 12 increases the flow of the third port, increasing the liquid flowing to the engine oil circuit, strengthening the cooling effect. When the oil temperature is low or the lubricating oil demand decreases, the bypass valve 12 reduces the flow of the third port to avoid excessive cooling.

[0088] The pressure sensor P1 is arranged at the first port (liquid passage from the compression chamber 2) of the bypass valve 12, and when the liquid pressure is high, the bypass valve 12 dynamically adjusts the opening degree to balance the flow distribution of the second port and the third port. When the liquid pressure drops below the set value, the bypass valve 12 can preferentially ensure the key lubrication requirement and improve the engine oil supply ratio. The pressure sensor P2 is arranged at the liquid outlet of the exhaust gas heat exchanger 8, and if the pressure is too high, it indicates that the flow resistance is large, and the second port flow can be appropriately reduced to optimize the flow path and reduce the liquid flow loss.

[0089] In the preferred implementation of the present application, the bypass valve 12 can use an electrically controlled proportional valve or a step motor controlled valve, which receives signals from temperature and pressure sensors and combines the flow demand calculated by the ECU (Electronic Control Unit) or PLC (Programmable Logic Controller) to dynamically adjust.

[0090] Through the above configuration, the bypass valve 12 can flexibly control the liquid flow direction, realize reasonable distribution of the mass flow rate of the waste heat utilization device liquid outlet between the exhaust gas heat exchanger 8 and the engine oil circuit, reduce the liquid flow loss, and improve the system thermal management performance.

[0091] In the preferred implementation of the present application, the heat absorber 5 uses a variable temperature heat absorption method to realize efficient heat exchange of exhaust gas waste heat. In order to further strengthen the heat exchange, the heat absorber 5 is provided with multi-stage heat exchange tube bundles or finned tubes inside to realize temperature stratified heat exchange. The heat exchange efficiency is optimized by different regions of heat exchange coefficient, and structures such as corrugated fins, porous plates or spiral flow channels are used to enhance the turbulent effect, prolong the heat exchange path and improve the heat exchange capacity. The system design is based on the engine exhaust gas temperature range of 200-300℃, and the inlet and outlet temperature difference is ≥150℃, to ensure the effective recovery of exhaust gas waste heat. The temperature of the heat absorber 5 changes in a gradient along the flow direction, so that the working medium forms a temperature glide in the expansion chamber 7.

[0092] The waste heat utilization device of the present application adopts a high pressure ratio design, so that the working medium forms a large temperature glide in the expansion chamber 7, optimizing the heat exchange efficiency. For example, the average temperature of the working medium flowing out of the expansion chamber 7 is at least 100℃ lower than the average temperature of the working medium flowing into the expansion chamber 7, ensuring that the waste heat utilization device has high thermal efficiency.

[0093] To further optimize the heat exchange process, the heat absorber 5 is connected in parallel with the bypass pipe 15, and the flow direction of the working medium is adjusted by the control valve 6: the working medium entering the expansion chamber 7 flows through the heat absorber 5 to realize large temperature glide heat exchange; the working medium flowing out of the expansion chamber 7 passes through the bypass pipe.

[0094] Compared with the prior art, mechanical work is usually output by a piston, a crank, and a connecting rod mechanism, which increases the system cost and volume, especially for commercial vehicles and engineering machinery, the space for arranging the waste heat utilization device is small, which limits the application. In view of the above problems, the present application directly utilizes the pressure potential energy generated by the tail gas waste heat to drive the engine oil, replacing the traditional mechanical work output mode:

[0095] 1. Reduce the components such as piston, crank, simplify the system structure, reduce the cost and volume.

[0096] 2. Avoid the layout restriction caused by the crankshaft connection, improve the adaptability of the system.

[0097] 3. Eliminate the efficiency conversion loss of the liquid pump, improve the oil pumping efficiency. For example, the efficiency of the traditional liquid pump is usually less than 70%, while the present device directly utilizes the pressure potential energy, improves the overall energy efficiency.

[0098] Through this optimization scheme, the waste heat utilization device not only improves the engine performance, but also reduces the intermediate link of mechanical work output in the traditional waste heat utilization mode, realizes a more efficient and more compact system design.

[0099] Embodiment 2

[0100] Referring to the drawings attached to the specification Figure 2 , the embodiment includes all the structures of embodiment 1, and the engine waste heat utilization device further includes a heat exchanger 13. The heat exchanger 13 has two independent flow paths for heat exchange of the liquid, so as to optimize the heat recovery efficiency of the system. The first flow path of the heat exchanger 13 is connected with the liquid outlet of the heat absorber 5 and the liquid inlet valve 9 of the compression chamber 2, so as to ensure that the liquid is subjected to heat exchange treatment before entering the compression chamber 2, and the temperature of the liquid is reduced. The second flow path is connected with the liquid outlet valve 10 of the compression chamber 2 and the liquid inlet of the tail gas heat exchanger 8, so that the liquid discharged from the compression chamber 2 is preheated by the heat exchanger 13 before entering the tail gas heat exchanger 8, the temperature of the liquid at the inlet of the tail gas heat exchanger 8 is increased, and the utilization efficiency of the tail gas waste heat is improved.

[0101] Further, the liquid inlet valve 9 and the liquid outlet valve 10 adopt one-way valves, so that the liquid flow direction is fixed, backflow is prevented, and the stability of the system is improved. At the same time, due to the characteristics of the one-way valve, automatic flow direction adjustment can be realized without complex control strategy, so as to reduce the complexity of the control system and improve the reliability of the system.

[0102] Embodiment 3

[0103] Referring to the drawings attached to the specification Figure 3On the basis of embodiment 1, the engine waste heat utilization device further comprises a hydraulic motor 14 and a cooling water pump 17. The hydraulic motor 14 is used to convert the pressure energy of liquid flow into mechanical energy. The first end of the hydraulic motor 14 is communicated with the liquid outlet valve 10 through a pipeline, and the second end is communicated with the liquid inlet valve 9 through a pipeline, forming a closed hydraulic circuit.

[0104] When the liquid is discharged from the liquid outlet valve 10, it flows through the pipeline and the hydraulic motor 14 in turn, driving the rotor of the hydraulic motor 14 to rotate in the process, thereby outputting mechanical work. After passing through the hydraulic motor 14, the pressure of the liquid is reduced, and finally flows into the liquid inlet valve 9, returning to the inside of the system, completing the cycle.

[0105] Preferably, the hydraulic motor 14 is connected with the engine cooling water pump 17, and the cooling water pump 17 is driven to operate by the rotation of the hydraulic motor 14, realizing the power replacement of the engine cooling water pump. This design can reduce the dependence of the engine waste heat utilization device on the crankshaft-connecting rod mechanism, reduce the complexity of the engine transmission system, improve the energy utilization efficiency, and at the same time reduce the additional power loss, and optimize the overall performance of the engine.

[0106] Embodiment 4

[0107] Referring to the drawings accompanying the specification Figure 4 On the basis of embodiment 1, in order to prevent the liquid from entering the heat absorber and the heat radiator and avoid the leakage of the working medium caused by the dissolution of the working medium in the liquid, the present application sets a diaphragm 16 in the compression chamber 2. The diaphragm 16 can be a film or a bellows, which is used to isolate the working medium and the liquid, ensure the stable operation of the system, and improve the heat exchange efficiency. The design of the diaphragm 16 needs to meet the requirements of high sealing property, corrosion resistance, and deep shrinkage, so as to adapt to the dynamic pressure change of the working medium and the fluid environment.

[0108] Specifically, the diaphragm 16 is arranged in the compression chamber 2, forming a sealed space with the chamber body, effectively preventing the working medium from directly contacting with the liquid. One side of the diaphragm contacts with the working medium, and the other side contacts with the liquid, and it adapts to the pressure change in the chamber through elastic deformation. The diaphragm 16 is made of plastic or metal. When the pressure of the working medium rises, the diaphragm expands to the liquid side; when the pressure of the liquid rises, the diaphragm retracts, thereby dynamically balancing the pressure between the working medium and the liquid.

[0109] During the system operation, the working medium and the liquid are located on both sides of the diaphragm 16, ensuring that they are physically separated, and the working process includes: pushing the ejector 4 to move towards the compression chamber 2, the volume of the expansion chamber increases, the pressure of the working medium rises, the liquid pressure rises synchronously, pushing the liquid outlet valve 10 to open, and the liquid flows out of the compression chamber 2. Push the ejector 4 to move towards the expansion chamber 7, the volume of the expansion chamber decreases, the pressure drops, the liquid inlet valve 9 opens, and the external liquid enters the compression chamber 2. During the entire cycle, the diaphragm 16 separates the working medium and the liquid, ensuring that the working medium and the liquid do not come into direct contact, preventing the working medium from dissolving and losing, and maintaining the sealing property and pressure stability of the system.

[0110] The application realizes the recycling of the working medium and improves the waste heat recovery efficiency by setting the compression chamber and the expansion chamber in the cylinder and using the ejector to drive the working medium to reciprocate between the two. Through the parallel design of the bypass pipeline and the switching valve, the heat exchange loss is reduced. In addition, the setting of the liquid inlet valve and the liquid outlet valve makes the liquid in the compression chamber form a pressure balance mechanism with the working medium, effectively improving the energy transfer efficiency. Preferably, the combination of the exhaust gas heat exchanger and the heat absorber recovers the high-temperature exhaust gas and effectively transfers the heat to the working medium, improving the waste heat utilization efficiency. The liquid inlet valve in the compression chamber is in communication with the engine oil pan, reducing energy consumption. The setting of the bypass valve makes the liquid flow flexible adjustment, improving the heat exchange efficiency and system adaptability. The application also separates the liquid and the working medium by the diaphragm, ensuring that the two flow independently, improving the system stability. The hydraulic motor directly drives the cooling water pump through the hydraulic energy generated by the liquid flow, reducing the mechanical load and improving the energy efficiency.

[0111] The above-mentioned is only an embodiment of the present application, and the common knowledge of specific structures and characteristics in the scheme is not described in detail. For those skilled in the art, it is obvious that the present application is not limited to the details of the above-mentioned exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. An engine waste heat utilization device, characterized in that: It includes a cylinder (1), a radiator (3), a heat absorber (5), an ejector (4), a bypass pipe (15), a switching valve (6) and a diaphragm (16); A compression chamber (2) and an expansion chamber (7) are provided inside the cylinder (1); the displacer (4) is provided inside the cylinder (1) and is used to drive the working medium to flow back and forth between the compression chamber (2) and the expansion chamber (7); The heat absorber (5) and the bypass pipe (15) are arranged in parallel; The switching valve (6) is arranged between the expansion chamber (7), the heat absorber (5) and the bypass pipe (15), and is used to selectively control the flow of the working medium through the heat absorber (5) or the bypass pipe (15); The radiator (3) has a first end and a second end, wherein the first end is in fluid communication with the compression chamber (2), and the second end is directly connected to a bypass pipe (15), and the working medium enters the bypass pipe (15) from the expansion chamber (7); The heat absorber (5) has a first end and a second end, wherein the first end is in fluid communication with the compression chamber (2), and the second end is in fluid communication with the expansion chamber (7), and the working medium enters the expansion chamber (7) from the heat absorber (5); The bypass pipe (15) includes a first end and a second end, the first end being in fluid communication with the expansion chamber (7), and the second end being in fluid communication with the compression chamber (2); The compression chamber (2) contains liquid and includes a liquid inlet valve (9) and a liquid outlet valve (10), both of which are one-way valves; The liquid inlet valve (9) of the compression chamber (2) is in communication with the oil pan of the engine, for receiving and guiding the oil from the oil pan to flow into the compression chamber (2); the liquid outlet valve (10) of the compression chamber (2) has a fluid outlet end in communication with the oil supply pipeline of the engine, for controlling the liquid in the compression chamber (2) to be delivered to the oil supply pipeline; The diaphragm (16) is arranged in the compression chamber (2) and is used to form a first fluid chamber and a second fluid chamber in the compression chamber (2); the first fluid chamber is used to accommodate liquid, and the fluid is allowed to enter and exit through a liquid inlet valve (9) and a liquid outlet valve (10); the second fluid chamber is used to accommodate a working medium, and is connected to the expansion chamber (7) through a pipeline to achieve a circulating flow of the working medium between the expansion chamber (7) and the compression chamber (2).

2. The engine waste heat utilization device according to claim 1, characterized in that: It also includes an exhaust gas heat exchanger (8), which is arranged on the exhaust gas discharge side of the engine, and the heat of the exhaust gas is transferred to the heat absorber (5) through a heat transfer medium.

3. The engine waste heat utilization device according to claim 2, characterized in that: The heat absorber (5) and the tail gas heat exchanger (8) are both provided with a liquid inlet and a liquid outlet, and heat is exchanged between the heat absorber (5) and the tail gas heat exchanger (8) through liquid; the liquid outlet of the heat absorber (5) is connected to the liquid inlet valve (9) of the compression chamber (2) via a fluid channel, and the liquid inlet of the tail gas heat exchanger (8) is connected to the liquid outlet valve (10) of the compression chamber (2) via a fluid channel.

4. The engine waste heat utilization device according to claim 2, characterized in that: The invention also comprises a bypass valve (12), which is configured to have at least three fluid interfaces for adjusting the distribution ratio of liquid between different circuits, wherein: The first fluid interface of the bypass valve (12) is fluidically connected to the liquid inlet valve (9) or the liquid outlet valve (10) of the compression chamber (2) to control the liquid flow path entering or exiting the compression chamber (2); The second fluid interface of the bypass valve (12) is fluidically connected to the liquid inlet of the exhaust gas heat exchanger (8) for guiding the liquid into the exhaust gas heat exchanger (8) for heat exchange; The third fluid interface of the bypass valve (12) is fluidically connected to the oil supply line of the engine or the oil pan oil circuit of the engine to control the liquid to enter the engine lubrication system or return to the oil pan; The bypass valve (12) is also configured to dynamically adjust the flow ratio of the liquid passing through the second fluid interface and the third fluid interface.

5. The engine waste heat utilization device according to claim 2, characterized in that: The heat absorber (5) adopts a variable temperature heat absorption structure; The temperature difference between the liquid temperature at the liquid outlet end of the tail gas heat exchanger (8) and the liquid temperature at the liquid inlet end thereof is ≥150°C.

6. The engine waste heat utilization device according to claim 2, characterized in that: It also includes a heat exchanger (13), which is constructed with two independent fluid passages, namely a first flow path and a second flow path, for heat exchange and circulation of liquid.

7. The engine waste heat utilization device according to claim 6, characterized in that: The first flow path connects the liquid outlet of the heat absorber (5) and the liquid inlet valve (9) of the compression chamber (2), and is used to transport the heat energy released from the heat absorber (5) to the compression chamber (2), so as to improve the preheating of the liquid inside the compression chamber (2); the second flow path connects the liquid outlet valve (10) of the compression chamber (2) and the liquid inlet of the exhaust gas heat exchanger (8), and is used to guide the liquid discharged from the compression chamber (2) into the exhaust gas heat exchanger (8), so as to exchange heat with the waste heat of the exhaust gas.

8. The engine waste heat utilization device according to claim 1, characterized in that: The invention also includes a hydraulic motor (14), the hydraulic motor (14) is in fluid communication with the liquid outlet valve (10) through a pipeline, and is in fluid communication with the liquid inlet valve (9) through a pipeline; and an engine cooling water pump (17), the hydraulic motor (14) is mechanically connected to the engine cooling water pump, and is used to drive the engine cooling water pump (17) to operate by utilizing hydraulic energy generated by the flow of liquid; And / or, it further comprises a motor, which is connected to the ejector (4) in a power-connected manner and is used to drive the ejector (4) to reciprocate along the cylinder (1).

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