JP6020242B2 - Waste heat utilization device for internal combustion engine - Google Patents

Description

  The present invention relates to a waste heat utilization apparatus for an internal combustion engine.

  Conventionally, a waste heat utilization apparatus that utilizes waste heat of an internal combustion engine is known. For example, Patent Document 1 discloses a boiler (referred to as a steam generator in Patent Document 1) that uses a heat of exhaust gas from an internal combustion engine (that is, waste heat) to make a working fluid a gas, and is discharged from the boiler. In addition, a waste heat utilization device is disclosed that includes a recovery device that recovers thermal energy from the working fluid (in Japanese Patent Application Laid-Open No. 2004-228561, the vehicle interior heating device corresponds to this). The waste heat utilization apparatus according to Patent Document 1 collects thermal energy from a working fluid heated by waste heat of an internal combustion engine and uses it for heating for a vehicle compartment.

JP 2010-156315 A

  In the case of the waste heat utilization apparatus according to Patent Document 1, when the internal combustion engine is at a cold start, the vaporization of the working fluid in the boiling device may be insufficient. In this case, it may be difficult to exhibit the performance of the recovery device at an early stage.

  An object of the present invention is to provide a waste heat utilization device for an internal combustion engine that can quickly exhibit the performance of the recovery device at the time of cold start of the internal combustion engine.

  An internal combustion engine waste heat utilization device according to the present invention includes a recovery device that recovers energy from a working fluid, and a first boiling device that uses the liquid working fluid as a gaseous working fluid using waste heat of the internal combustion engine. A second boiling device having a heat capacity smaller than the heat capacity of the first boiling device and using the waste working heat of the internal combustion engine as the gaseous working fluid. A passage for supplying the gaseous working fluid discharged from the boiling device to the second boiling device or the recovery device; and a passage for supplying the gaseous working fluid discharged from the second boiling device to the recovery device; And a passage for supplying the working fluid of the liquid discharged from the recovery device to the first boiling device and the second boiling device.

  According to the internal combustion engine waste heat utilization apparatus according to the present invention, the first boiling unit generates the gaseous working fluid using the waste heat of the internal combustion engine, and supplies the working fluid to the second boiling unit or the recovery apparatus. In addition, it is possible to generate a gaseous working fluid using the waste heat of the internal combustion engine and supply it to the recovery device also in the second boiler. In addition, since the heat capacity of the second boiler is smaller than the heat capacity of the first boiler, even when the internal combustion engine is cold start, the working fluid is quickly vaporized by the second boiler and supplied to the recovery device. can do. As a result, the performance of the recovery device can be exhibited at an early stage when the internal combustion engine is cold started.

  In the above configuration, the waste heat of the internal combustion engine is heat of the exhaust gas of the internal combustion engine, and the second boiling device may be disposed upstream of the first boiling device in the flow direction of the exhaust gas. .

  According to this structure, compared with the case where the 2nd boiling machine is arrange | positioned in the flow direction of exhaust_gas | exhaustion rather than the 1st boiling machine, a working fluid can be vaporized effectively by a 2nd boiling machine. it can. As a result, the performance of the recovery device can be exhibited earlier when the internal combustion engine is cold started.

  ADVANTAGE OF THE INVENTION According to this invention, the waste heat utilization apparatus of the internal combustion engine which can exhibit the performance of a collection | recovery apparatus at the time of the cold start of an internal combustion engine can be provided.

FIG. 1 is a schematic diagram illustrating a configuration of a waste heat utilization apparatus according to the first embodiment. FIG. 2 is a schematic diagram illustrating a configuration of a waste heat utilization apparatus according to a comparative example. FIG. 3A is a schematic diagram showing a boiling curve of the working fluid. FIG.3 (b) is a schematic diagram which shows the heat-transfer performance of the 1st boiling machine and collection | recovery apparatus of the waste-heat utilization apparatus which concerns on a comparative example. FIG.3 (c) is a schematic diagram which shows the heat transfer performance of the whole boiling device of the waste-heat utilization apparatus which concerns on Example 1, and a collection | recovery apparatus. FIG. 4 is a schematic diagram illustrating the configuration of the waste heat utilization apparatus according to the second embodiment.

  Hereinafter, modes for carrying out the present invention will be described.

  An internal combustion engine waste heat utilization apparatus 5 according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram showing the configuration of the waste heat utilization device 5. The waste heat utilization apparatus 5 shown in FIG. 1 is mounted on a vehicle. The waste heat utilization device 5 includes an internal combustion engine 10, an exhaust passage 15 through which exhaust gas from the internal combustion engine 10 passes, a first boiling device 20, a second boiling device 30, and a recovery device 40. The waste heat utilization device 5 includes a passage 50a, a passage 50b, a passage 60a, and a passage 60b as passages through which the working fluid of the waste heat utilization device 5 passes. The type of the internal combustion engine 10 is not particularly limited, and various engines such as a gasoline engine and a diesel engine can be used. In this embodiment, a gasoline engine is used as an example of the internal combustion engine 10. The type of the working fluid is not particularly limited as long as it can be heated to the gas by the exhaust heat of the internal combustion engine 10 to become a gas. In the present embodiment, a refrigerant that can be used for cooling the internal combustion engine 10 is used as an example of the working fluid. As a specific example of the refrigerant, for example, water, an antifreeze liquid in which water and ethylene glycol are mixed, or the like can be used. In this embodiment, water is used as an example of the refrigerant used for the working fluid.

  The first boiling device 20 and the second boiling device 30 are devices that convert a liquid working fluid into a gaseous working fluid using waste heat of the internal combustion engine 10. In the present embodiment, the exhaust heat of the internal combustion engine 10 is used as an example of the waste heat of the internal combustion engine 10. The structure of the 1st boiling machine 20 and the 2nd boiling machine 30 which concerns on a present Example is as follows. First, the exhaust passage 15 is inserted into the first and second boilers 20 and 30. The second boiling device 30 according to the present embodiment is arranged upstream of the first boiling device 20 in the exhaust flow direction. Inside the first boiling device 20, the upper side of the exhaust passage 15 is referred to as an upper portion 21, and the lower side is referred to as a lower portion 22. Further, in the second boiling device 30, the upper side of the exhaust passage 15 is referred to as an upper portion 31, and the lower side is referred to as a lower portion 32.

  A liquid working fluid is stored in the lower part 22 of the first boiler 20. The liquid working fluid stored in the lower part 22 is boiled by being heated by the heat of the exhaust in the exhaust passage 15. As a result, a gaseous working fluid (specifically, steam) is generated in the first boiler 20. The generated gaseous working fluid is stored in the upper part 21 and then flows into the upper part 31 of the second boiler 30 through a passage 60a described later. A liquid working fluid is stored in the lower part 32 of the second boiling device 30. The liquid working fluid stored in the lower part 32 boils by being heated by the heat of the exhaust gas in the exhaust passage 15. As a result, a gaseous working fluid is generated in the second boiler 30. The gaseous working fluid is stored in the upper portion 31 and then supplied to the recovery device 40 through a passage 60b described later.

  As described above, the first boiling device 20 and the second boiling device 30 according to the present embodiment heat the liquid working fluid with the heat of the exhaust gas in the exhaust passage 15 (that is, the waste heat of the internal combustion engine 10), thereby generating gas. Working fluid. Moreover, the lower part 22 of the 1st boiling machine 20 and the lower part 32 of the 2nd boiling machine 30 have a function as a storage part which stores a liquid working fluid, The upper part 21 of the 1st boiling machine 20, and the 2nd boiling machine 30 The upper part 31 has a function as a storage part for storing a gaseous working fluid. The structures of the first boiling device 20 and the second boiling device 30 are capable of heating the liquid working fluid in these boiling devices with the waste heat of the internal combustion engine 10 to form a gaseous working fluid. For example, it is not limited to the structure of FIG.

  In the present embodiment, the heat capacity (J / K) of the second boiling device 30 is smaller than the heat capacity of the first boiling device 20. Specifically, the volume of the second boiling device 30 according to the present embodiment is smaller than the volume of the first boiling device 20. Thereby, the amount of heat (that is, the heat capacity) required to raise the second boiling device 30 by 1 ° C. per unit time is smaller than the heat capacity of the first boiling device 20.

  The passage 50 a connects the recovery device 40 and the lower part 22 of the first boiling device 20. The passage 50 b connects the middle of the passage 50 a and the lower part 32 of the second boiling device 30. Here, the working fluid discharged from the recovery device 40 is mainly liquid. Therefore, the passage 50 a functions as a passage for supplying the liquid working fluid discharged from the recovery device 40 to the first boiling device 20. The passage 50 b has a function as a passage for supplying the second working fluid 30 with the liquid working fluid discharged from the recovery device 40. It is possible that the working fluid discharged from the recovery device 40 is mixed with a gaseous working fluid. The gaseous working fluid is also supplied to the first boiling device 20 through the passage 50a, and the passage 50b. And is supplied to the second boiler 30.

  The passage 60 a connects the upper part 21 of the first boiling device 20 and the upper part 31 of the second boiling device 30. The passage 60 b connects the upper part 31 of the second boiling device 30 and the recovery device 40. The passage 60 a has a function as a passage for supplying the gaseous working fluid discharged from the first boiling device 20 to the second boiling device 30. Further, the passage 60 b has a function as a passage for supplying the gaseous working fluid discharged from the second boiling device 30 to the recovery device 40.

  The recovery device 40 is a device that recovers energy from the working fluid. In the present embodiment, as an example of the recovery device 40, a heating device that warms the vehicle compartment (cabin) of the vehicle is used. In this case, the recovery device 40 warms the air using the thermal energy of the gaseous working fluid supplied to the recovery device 40 through the passage 60b, and blows the warmed air to the passenger compartment. Specifically, an internal passage that communicates the passage 60b and the passage 50a is provided inside the recovery device 40 as the passenger compartment heating device according to the present embodiment. When the gaseous working fluid that has passed through the passage 60b flows into the internal passage, heat is exchanged between the heat of the working fluid in the internal passage and the air around the internal passage. Is warmed. The collection device 40 includes a blower that blows air around the internal passage to the passenger compartment. The blower starts air blowing to the passenger compartment when the user of the vehicle turns on the operation start switch of the collection device 40. When the blower starts to blow into the vehicle compartment, warm air around the internal passage is supplied to the vehicle compartment. In this way, the recovery device 40 according to the present embodiment recovers thermal energy from the working fluid heated by the waste heat of the internal combustion engine 10, and uses the air heated by the recovered thermal energy for heating the passenger compartment. Used. However, the specific structure of the collection | recovery apparatus 40 as a vehicle interior heating apparatus is not limited to this.

  In addition, the specific structure of the collection | recovery apparatus 40 is not limited to the vehicle interior heating apparatus like a present Example. If the other example of the collection | recovery apparatus 40 is given, the warming-up apparatus for promoting warming-up of the internal combustion engine 10 can also be used as the collection | recovery apparatus 40, for example. Specifically, a working fluid passage disposed around the internal combustion engine 10 (specifically, at least one of a cylinder block and a cylinder head of the internal combustion engine 10) can be used as the warm-up device. In this case, the thermal energy of the working fluid supplied to the working fluid passage as the warm-up device via the passage 60b is recovered in the working fluid passage and used to warm the internal combustion engine 10.

  The waste heat utilization apparatus 5 according to the present embodiment operates as follows. First, the liquid working fluid stored in the lower portion 22 of the first boiling device 20 and the lower portion 32 of the second boiling device 30 is vaporized by being heated by the heat of the exhaust gas in the exhaust passage 15 to be vaporized. And move to the upper part 21 and the upper part 31, respectively. The working fluid in the upper part 21 of the first boiler 20 is supplied to the upper part 31 of the second boiler 30 through the passage 60a. The working fluid in the upper part 31 of the second boiler 30 is supplied to the recovery device 40 through the passage 60b. The heat of the gaseous working fluid supplied to the recovery device 40 is recovered by the recovery device 40 and used for heating the passenger compartment. As a result, the gaseous working fluid is condensed into a liquid working fluid. The working fluid discharged from the recovery device 40 passes through the passage 50 a, a part thereof is supplied to the lower part 22 of the first boiler 20, and the remaining part passes through the passage 50 b to the lower part 32 of the second boiler 30. Supplied.

  The waste heat utilization device 5 is provided with a working fluid pumping device such as a pump in the passage 50a, for example, and the working fluid pumping device forcibly supplies the liquid working fluid to the first boiling device 20 or the second boiling device 30. It may be configured to.

  Then, the effect of the waste heat utilization apparatus 5 is demonstrated, comparing with the waste heat utilization apparatus 100 which concerns on a comparative example. FIG. 2 is a schematic diagram illustrating a configuration of the waste heat utilization apparatus 100 according to the comparative example. The waste heat utilization apparatus 100 is not provided with the second boiler 30, the passage 60 a, the passage 60 b, and the passage 50 b, and has a passage 110 that connects the first boiler 20 and the recovery device 40. This is different from the waste heat utilization apparatus 5 according to this embodiment. In the case of the waste heat utilization apparatus 100 according to the comparative example, when the internal combustion engine 10 is at a cold start (specifically, when the internal combustion engine 10 is started in a state where the refrigerant temperature of the internal combustion engine 10 is lower than a predetermined temperature). ), The vaporization of the working fluid in the first boiler 20 may be insufficient. In this case, it may be difficult to exhibit the performance of the recovery device 40 at an early stage. The problem of the waste heat utilization apparatus 100 according to this comparative example will be specifically described as follows.

FIG. 3A is a schematic diagram showing a boiling curve of the working fluid. The vertical axis represents the heat flux, and the horizontal axis represents the degree of superheat (the difference between the saturation temperature of the working fluid and the temperature of the heating surface (which is substantially equal to the exhaust temperature)). FIG. 3A shows a boiling curve (curve 1) when the pressure of the working fluid is high and a boiling curve (curve 2) when the pressure of the working fluid is low. In FIG. 3A, the AB region is a non-boiling region, the B-C-D region is a nucleate boiling region, the D-E region is a transition boiling region, and the E-F region. Is the film boiling region. Ideally, a working fluid having a degree of superheat (ΔT _sat ) corresponding to D in FIG.

When curve 1 and curve 2 are compared in the degree of superheat (ΔT _sat ) corresponding to D in FIG. 3A, the heat flux (q) of curve 1 (high pressure) is the heat flow of curve 2 (low pressure). It is higher than the bundle (q). That is, the higher the pressure of the gaseous working fluid (hereinafter, sometimes referred to as vapor pressure) can have higher heat transfer performance. As a result, the higher the vapor pressure of the working fluid, the higher the recovery device 40. It can be seen that can be operated more efficiently. Conversely, if the working fluid has a low vapor pressure, it may be difficult to exhibit the performance of the recovery device 40. This will be described more specifically with reference to the drawings as follows.

  FIG. 3B is a schematic diagram showing the heat transfer performance of the first boiling device 20 and the recovery device 40 of the waste heat utilization device 100 according to the comparative example. Specifically, the heat transfer performance of the first boiling device 20 in FIG. 3B is the heat transfer performance (that is, the heat receiving performance) when the first boiling device 20 receives the heat of the working fluid at the cold start. I mean. Further, the heat transfer performance of the recovery device 40 in FIG. 3B indicates the heat transfer performance (that is, the condensation performance) when the recovery device 40 takes heat from the working fluid at the cold start. In the case of the waste heat utilization apparatus 100 according to the comparative example, the condensing performance of the working fluid in the recovery device 40 is higher than the heat receiving performance of the working fluid in the first boiling device 20 at the cold start. In this case, since the working fluid is quickly condensed in the recovery device 40 at the time of cold start, the vapor pressure of the working fluid in the passage 110 is not sufficiently increased until the recovery device 40 is warmed up. Therefore, in the case of the waste heat utilization apparatus 100 according to the comparative example, when the internal combustion engine 10 is in cold start, it is difficult to generate a working fluid having a sufficiently high vapor pressure in the first boiling device 20 at an early stage. Therefore, it becomes difficult to exhibit the performance of the recovery device 40 at an early stage.

  On the other hand, according to the waste heat utilization apparatus 5 according to the present embodiment, the first boiling device 20 generates the gaseous working fluid using the waste heat of the internal combustion engine 10 and uses the working fluid as the second boiling device. 30, and also in the second boiling unit 30, a gaseous working fluid can be generated using the waste heat of the internal combustion engine 10 and supplied to the recovery device 40. That is, the working fluid can be gasified and supplied to the recovery device 40 by both the first boiling device 20 and the second boiling device 30. Further, since the heat capacity of the second boiler 30 is smaller than the heat capacity of the first boiler 20, even if the exhaust gas temperature is low, such as when the internal combustion engine 10 is cold-started, the second boiler 30. Thus, the working fluid can be vaporized at an early stage and supplied to the recovery device 40. Thereby, the working fluid having a high vapor pressure can be supplied to the recovery device 40 at an early stage. As a result, the performance of the recovery device 40 can be exhibited at an early stage when the internal combustion engine 10 is cold started.

  The effect of the waste heat utilization apparatus 5 according to the above-described embodiment will be described with reference to the drawings. FIG. 3C is a schematic diagram showing the heat transfer performance of the entire boiling device (first boiling device 20 and second boiling device 30) of the waste heat utilization device 5 and the recovery device 40. Specifically, the heat transfer performance of the entire boiling device in FIG. 3C means the heat receiving performance of the working fluid of the entire boiling device at the cold start. The heat transfer performance of the recovery device 40 in FIG. 3C means the working fluid condensation performance of the recovery device 40 during cold start. According to the waste heat utilization device 5, since the heat receiving performance of the entire boiling device exceeds the condensing performance of the recovery device 40 at the cold start, the working fluid is effectively high-pressure at the entire condenser at the cold start. Can be As a result, the performance of the recovery device 40 can be exhibited early at the time of cold start. Further, since the recovery device 40 according to the present embodiment is a heating device for the passenger compartment, according to the waste heat utilization device 5 according to the present embodiment, even if the internal combustion engine 10 is cold start, The performance of the heating device can be exhibited early, and the passenger compartment can be warmed up early.

  The waste heat utilization apparatus 5 according to the present embodiment does not need to perform special control such as switching the passage through which the working fluid passes when the waste heat utilization apparatus 5 is operated, so that the overall configuration is simple. It can be said. Therefore, the degree of freedom of mounting the waste heat utilization device 5 on the vehicle is high. Therefore, the waste heat utilization device 5 can be easily mounted on a wide range of vehicle types.

  In the present embodiment, the second boiling device 30 is arranged upstream of the first boiling device 20 in the flow direction of the exhaust gas. However, the present invention is not limited to this. Even if the second boiling device 30 is arranged downstream of the first boiling device 20 in the flow direction of the exhaust gas, the waste heat utilization device 5 can exhibit the above-described effects. However, since the temperature of the exhaust gas in the exhaust passage 15 is higher on the upstream side than on the downstream side, the second boiling device 30 is arranged upstream of the first boiling device 20 in the flow direction of the exhaust gas as in the present embodiment. The working fluid can be vaporized more effectively by the second boiling device 30 than when the second boiling device 30 is disposed downstream of the first boiling device 20. As a result, the performance of the recovery device 40 can be exhibited earlier when the internal combustion engine 10 is cold started.

  By the way, for example, when the waste heat utilization device 100 according to the comparative example of FIG. 2 includes the second boiling device 30 instead of the first boiling device 20 (this waste heat utilization device is used as the waste heat utilization method according to Comparative Example 2). The waste heat utilization apparatus according to Comparative Example 2 operates earlier at the time of cold start than the waste heat utilization apparatus 100 because the heat capacity of the entire boiling device is smaller than that of the waste heat utilization apparatus 100. It is also possible that the fluid can be vaporized. However, when the waste heat utilization apparatus according to the comparative example 2 and the waste heat utilization apparatus 5 according to the present embodiment are compared, the entire boiling unit (the first boiling device 20 and the first boiling apparatus 20) of the waste heat utilization apparatus 5 according to the present embodiment is compared. The amount of steam obtained by the two-boiler 30) is larger than the amount of steam obtained by the whole boiling device (only the second boiling device 30) according to the waste heat utilization apparatus according to the comparative example 2, and therefore according to this embodiment. The waste heat utilization device 5 can operate the recovery device 40 more effectively during the cold start than the waste heat utilization device according to Comparative Example 2. In this respect, the waste heat utilization apparatus 5 according to the present embodiment is superior to the waste heat utilization apparatus according to Comparative Example 2.

  Next, an internal combustion engine waste heat utilization apparatus 5a according to Embodiment 2 of the present invention will be described. FIG. 4 is a schematic diagram showing the configuration of the waste heat utilization apparatus 5a. The waste heat utilization device 5a is mounted on the vehicle in the same manner as the waste heat utilization device 5 according to the first embodiment. The waste heat utilization device 5a is different from the waste heat utilization device 5 according to the first embodiment shown in FIG. 1 in that a passage 60c is provided instead of the passage 60a and the passage 60b. The other structure of the waste heat utilization apparatus 5a is the same as that of the waste heat utilization apparatus 5.

  The passage 60 c includes a first passage portion 61 and a second passage portion 62. The first passage portion 61 connects the upper part 21 of the first boiling unit 20 and the upper part 31 of the second boiling unit 30. The second passage portion 62 connects the midway of the first passage portion 61 and the recovery device 40. The gaseous working fluid present in the upper portion 21 of the first boiling device 20 passes through the first passage portion 61 and the second passage portion 62 and flows into the recovery device 40. The gaseous working fluid present in the upper portion 31 of the second boiling device 30 passes through the first passage portion 61 and the second passage portion 62 and flows into the recovery device 40. Thus, the passage 60c according to the present embodiment has a function as a passage for supplying the working fluid of the gas discharged from the first boiling device 20 to the recovery device 40, and the gas discharged from the second boiling device 30. It also has a function as a passage for supplying the working fluid to the recovery device 40.

  The waste heat utilization apparatus 5a according to the present embodiment can achieve the same effects as those of the first embodiment as described below. Specifically, according to the waste heat utilization device 5 a, a gaseous working fluid can be generated using the waste heat of the internal combustion engine 10 in the first boiling unit 20, and this working fluid can be supplied to the recovery device 40. At the same time, also in the second boiler 30, a gaseous working fluid can be generated using the waste heat of the internal combustion engine 10 and supplied to the recovery device 40. That is, also in the present embodiment, as in the first embodiment, the working fluid can be made into a gas by both the first boiling device 20 and the second boiling device 30 and supplied to the recovery device 40. Thereby, even when the internal combustion engine 10 is in a cold start, the working fluid can be vaporized at an early stage and supplied to the recovery device 40 by the second boiling device 30 having a relatively small heat capacity. As a result, the performance of the recovery device 40 can be exhibited at an early stage when the internal combustion engine 10 is cold started.

  Also in the waste heat utilization apparatus 5a according to the present embodiment, since the second boiling device 30 is arranged upstream of the first boiling device 20 in the flow direction of the exhaust gas, the working fluid is driven by the second boiling device 30. Can be vaporized effectively. As a result, compared with the case where the second boiling device 30 is arranged downstream of the first boiling device 20, the performance of the recovery device 40 can be exhibited earlier at the time of cold start of the internal combustion engine 10. Can do. In addition, the waste heat utilization device 5a has a simple configuration as a whole because it is not necessary to perform special control such as switching the passage through which the working fluid passes when the waste heat utilization device 5a operates. Therefore, the degree of freedom of mounting the waste heat utilization device 5a on the vehicle is high, and as a result, it can be easily mounted on a wide range of vehicle types.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

5 Waste Heat Utilization Device 10 Internal Combustion Engine 20 First Boiler 30 Second Boiler 40 Recovery Device 50a, 50b Passage 60a, 60b, 60c Passage 100 Waste Heat Utilization Device 110 Passage

Claims (2)

A recovery device for recovering energy from the working fluid;
A first boiling device that uses the waste heat of an internal combustion engine to convert the liquid working fluid into the gas working fluid;
A second boiler having a heat capacity smaller than the heat capacity of the first boiler and converting the liquid working fluid into the gaseous working fluid using waste heat of the internal combustion engine;
A passage for supplying the working fluid in the form of gas discharged from the first boiling device to the second boiling device ;
A passage for supplying the recovery device with the gaseous working fluid discharged from the second boiler;
A waste heat utilization device for an internal combustion engine, comprising: a passage for supplying the working fluid in a liquid discharged from the recovery device to the first boiling device and the second boiling device. The waste heat of the internal combustion engine is the heat of the exhaust gas of the internal combustion engine,
2. The waste heat utilization device for an internal combustion engine according to claim 1, wherein the second boiling device is disposed upstream of the first boiling device in the flow direction of the exhaust gas.

Images