JP2009243387A - Engine exhaust heat recovery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use heat contained in fuel in an engine. <P>SOLUTION: The exhaust heat recovery system 1 is provided with a return fuel passage 8 through which return fuel returned to a fuel tank 4 flows; a heat storage vessel 3 into which the return fuel passage 8 is drawn, storing refrigerant circulating in the engine 2 inside thereof; and a first coolant passage 10, a second coolant passage 11 and a third coolant passage 15 through which the refrigerant given heat from the return fuel in the heat storage vessel 3 and circulating in the engine 2 flows. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus capable of utilizing waste heat of return fuel returned to a fuel tank.

  Conventionally, in order to suppress evaporation of gasoline in a gasoline tank, a gasoline cooling device that cools surplus gasoline whose temperature has increased by passing through a high-temperature engine room is disclosed in addition to adiabatic compression by a pump. .

  An improved version of such a gasoline cooling device is disclosed in Patent Document 1. The gasoline cooling device disclosed in Patent Document 1 discloses a configuration for the purpose of satisfactorily performing both cooling of gasoline and cooling of an automobile interior. Specifically, it has a configuration in which a heat storage agent is filled in a heat storage heat exchanger in which a cooled pipe and a cooling pipe are arranged. In this gasoline cooling device, when the cooling load is low, the solenoid valve is opened to flow a refrigerant into the cooling pipe, thereby cooling the heat storage agent and simultaneously cooling the gasoline in the cooled pipe. On the other hand, when the cooling load is high, the solenoid valve is closed and the gasoline flowing in the cooled pipe is cooled by the heat storage agent.

Japanese Utility Model Publication No. 4-129670

  Thus, the heat storage type heat exchanger in Patent Document 1 is arranged for the purpose of cooling gasoline, and the heat storage agent functions as a cooling agent. The heat of gasoline heat-exchanged in such a regenerative heat exchanger is carried away by the refrigerant, released to the atmosphere by a condenser, and no proposal has been made to utilize this heat. This also applies to other conventional gasoline cooling devices.

  Then, this invention makes it a subject to utilize the heat | fever which fuels, such as gasoline, have effectively.

  The engine waste heat recovery apparatus of the present invention that solves such a problem includes a return fuel passage through which return fuel flows, and heat storage means for recovering waste heat of the return fuel. 1). By setting it as such a structure, the collect | recovered waste heat can be stored in the thermal storage means which has a heat retention effect. Furthermore, the waste heat recovery apparatus can utilize the heat recovered in this way for increasing the temperature of each part. Such a waste heat recovery apparatus can be effectively used in an accumulator fuel system in a diesel engine. Some accumulator fuel injection systems in diesel engines return to the fuel tank without injecting part of the fuel accumulated in a high pressure state into the cylinder during fuel injection. Thus, the temperature of the fuel returning to the fuel tank rises when the pressure is reduced from the high pressure state. Thereby, such a fuel reaches a high temperature and has thermal energy. The waste heat recovery apparatus of the present invention can effectively use energy by recovering the waste heat of such fuel and utilizing this heat. The return fuel is not limited to the fuel that returns from the equipment related to the injection as described above, but includes fuel that returns to the fuel tank and that has recoverable heat. For example, the fuel that volatilized from the fuel tank is liquefied and returned to the fuel tank again is included in the return fuel.

  Such a waste heat recovery apparatus can be configured to include a refrigerant passage through which the refrigerant that circulates in the engine is supplied with heat in the heat storage means (Claim 2). By setting it as such a structure, the warming-up of an engine can be accelerated | stimulated using the heat | fever stored in the thermal storage means.

  In addition, such a waste heat recovery apparatus includes a refrigerant passage through which a refrigerant circulated in the engine is supplied with heat in the heat storage means, and the return fuel passage and the refrigerant passage are drawn into the heat storage means. In addition, a heat storage container filled with a heat storage agent can be provided (claim 3). Further, the heat storage means may be a heat storage container that stores therein the refrigerant flowing through the refrigerant passage and draws in the return fuel passage. By setting it as such a structure, the thermal storage means can store the waste heat of a return fuel.

  Such a waste heat recovery apparatus can be configured to include a cooling means for cooling the return fuel based on temperature information of the return fuel. By adopting such a configuration, it is possible to prevent damage due to an excessive temperature rise in the passage through which the fuel flows, such as when the temperature of the return fuel exceeds a preset threshold temperature. In addition, it is possible to suppress the inflow of the fuel that has reached a high temperature into the fuel tank and to suppress an increase in the temperature of the fuel in the fuel tank. In such a waste heat recovery apparatus, the cooling means includes a first bypass passage through which the return fuel bypasses the heat storage means, and the return fuel to the first bypass passage based on temperature information of the return fuel. And a cooler that cools the return fuel passing through the first bypass passage (Claim 6).

  Furthermore, such a waste heat recovery apparatus may be configured to include a second bypass passage through which the return fuel that has passed through the heat storage means bypasses the fuel tank (claim 7). With such a configuration, the return fuel maintained at a high temperature in the heat storage means can be directly used for injection. The temperature of the return fuel in the heat storage means is maintained even after the engine is stopped. Therefore, when the fuel in the fuel tank is at a low temperature, such as when the engine is started, the return fuel is passed through the second bypass passage, so that the fuel having a higher temperature than the low-temperature fuel in the fuel tank is brought into the cylinder. Can be jetted. As a result, the atomization of the fuel is improved, the ignitability is improved, and the engine startability is improved.

  In this waste heat recovery apparatus, the return fuel that has passed through the heat storage means is injected into the second bypass passage that bypasses the fuel tank, the temperature of the return fuel that has passed through the heat storage means, and the cylinder. And a second switching means for controlling the flow state of the return fuel to the second bypass passage based on the temperature of the fuel to be supplied (claim 8). By setting it as such a structure, the path | route which a return fuel distribute | circulates can be switched based on the temperature of a return fuel. Thereby, the temperature of the fuel injected into the cylinder can be improved, and the engine startability can be improved.

  The waste heat recovery apparatus of the present invention can effectively use energy by recovering the waste heat of the return fuel returned to the fuel tank and using it for warming up the engine.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a schematic configuration of a diesel engine (hereinafter simply referred to as “engine”) 2 incorporating a waste heat recovery apparatus 1 of the present invention.

  The waste heat recovery apparatus 1 includes a heat storage container 3, a fuel tank 4, a common rail 5, a fuel pump 6, a fuel passage 7, a return fuel passage 8, and injectors 9a, 9b, 9c, and 9d.

  The heat storage container 3 corresponds to the heat storage means of the present invention and is a tank having heat insulation properties, and can store a refrigerant therein. A first refrigerant passage 10 and a second refrigerant passage 11 through which refrigerant flows are connected to the heat storage container 3. The pipes forming the first refrigerant passage 10 and the second refrigerant passage 11 are inserted from the bottom surface 3 a side of the heat storage container 3 toward the inside of the heat storage container 3. The refrigerant flows into the heat storage container 3 through the first refrigerant passage 10 and flows out from the heat storage container 3 through the second refrigerant passage 11.

  The fuel passage 7 connects the fuel tank 4 and the common rail 5. A fuel pump 6 is disposed on the fuel passage 7. The fuel pump 6 compresses the fuel in the fuel tank 4 and supplies it to the common rail 5. The common rail 5 maintains the supplied fuel at a high pressure, and supplies the high-pressure fuel to injectors 9a, 9b, 9c, and 9d arranged in the respective cylinders.

  One end of the return fuel passage 8 opens into the fuel tank 4. The return fuel passage 8 branches in the middle of the passage and is connected to each of the injectors 9a, 9b, 9c, 9d.

  By the way, the fuel supplied from the common rail 5 to the injector 9a is divided into fuel that is injected into the cylinder and fuel that applies back pressure to the injection valve of the injector 9a. The fuel that gives back pressure to the injection valve of the injector 9 a is extracted from the injector 9 a when the injector 9 a injects fuel into the cylinder, and returns to the fuel tank 4 through the return fuel passage 8. Hereinafter, the fuel returning to the fuel tank 4 is referred to as “return fuel”. Such a fuel return is similarly performed in the injectors 9b, 9c, and 9d. The fuel released from the common rail 5 is also joined to the return fuel passage 8.

  In the return fuel passage 8, a part of the passage is drawn into the heat storage container 3. For this reason, in the heat storage container 3, the return fuel passing through the return fuel passage 8 and the refrigerant in the heat storage container 3 perform heat exchange.

  Further, the engine body 12 of the engine 2 includes a water jacket 13, and a water pump 14 is provided downstream of the water jacket 13. In addition, the engine 2 includes a third refrigerant passage 15 through which a refrigerant circulating in the engine 2 flows. The upstream end portion of the third refrigerant passage 15 is connected to the downstream portion of the water jacket 13, and the downstream end portion of the third refrigerant passage 15 is connected to the upstream portion of the water jacket 13. In other words, the refrigerant flows through a passage formed in a loop shape by the water jacket 13 and the third refrigerant passage 15. Further, a thermostat 16 and a radiator 17 are arranged in the third refrigerant passage 15 in order from the upstream side. The first refrigerant passage 10 and the fourth refrigerant passage 18 are connected to the thermostat 16. Further, the second refrigerant passage 11 is connected to the downstream side of the radiator 17 in the third refrigerant passage 15.

  The thermostat 16 is a switching valve that changes the path according to the temperature of the refrigerant. The thermostat 16 includes a path through which the refrigerant pumped from the water pump 14 is circulated along the third refrigerant path 15, a path to be sent to the first refrigerant path 10, and a path to be sent to the fourth refrigerant path 18. . The thermostat 16 causes the refrigerant to flow through the first refrigerant passage 10 and the fourth refrigerant passage 18 when the temperature of the refrigerant is low. On the other hand, when the temperature of the refrigerant is high, the thermostat 16 causes the refrigerant to flow through the first refrigerant passage 10, the fourth refrigerant passage 18, and the third refrigerant passage 15. The temperature of the refrigerant at which the thermostat 16 switches the path is a temperature at which it is determined that the engine body 12 has been warmed up.

  Further, an electric pump 19 and a first check valve 20 are arranged in the first refrigerant passage 10 in order from the side closer to the thermostat 16. A second check valve 21 is disposed in the second refrigerant passage 11. The electric pump 19 pumps the refrigerant in the first refrigerant passage 10 from the thermostat 16 side to the heat storage container 3 side. The first check valve 20 blocks the flow of the refrigerant in the first refrigerant passage 10 from the heat storage container 3 side to the thermostat 16 side. The second check valve 21 blocks the flow of the refrigerant in the second refrigerant passage 11 toward the heat storage container 3.

  Further, an electromagnetic valve 22 and a heater 23 are arranged in the fourth refrigerant passage 18 in order from the thermostat 16 side. When the solenoid valve 22 is closed, the refrigerant in the fourth refrigerant passage 18 is blocked. The heater 23 warms the air blown into the room by the heat of the refrigerant.

  The waste heat recovery apparatus 1 includes an ECU (Electronic Control Unit) 24. The ECU 24 is electrically connected to the electric pump 19 and transmits a control signal for driving and stopping to the electric pump 19. The ECU 24 is electrically connected to the electromagnetic valve 22 and transmits control signals for valve opening and closing to the electromagnetic valve 22.

  Next, the operation of the waste heat recovery apparatus 1 will be described. First, the case where the engine 2 has been warmed up and is operating will be described. When the engine 2 is in operation, the mechanical water pump 14 is operated, and the refrigerant flows through the water jacket 13 and the third refrigerant passage 15. The electric pump 19 is driven by receiving a drive signal from the ECU 24. When the engine 2 has been warmed up, the thermostat 16 forms a path so that the refrigerant can flow to the first refrigerant passage 10, the third refrigerant passage 15, and the fourth refrigerant passage 18. Among these, the refrigerant flowing through the third refrigerant passage 15 is cooled by the radiator 17. The refrigerant cooled by the radiator 17 flows into the water jacket 13.

  The refrigerant flowing into the first refrigerant passage 10 is pumped to the electric pump 19 and flows into the heat storage container 3. By the way, the temperature of the return fuel from the injectors 9a, 9b, 9c, 9d and the common rail 5 rises when the pressure drops from the high pressure state. For this reason, the fuel passing through the return fuel passage 8 is at a high temperature. In the heat storage container 3, the return fuel passing through the return fuel passage 8 and the refrigerant exchange heat. Thereby, in the heat storage container 3, the temperature of the refrigerant increases, and the temperature of the return fuel decreases. The refrigerant whose temperature has thus increased passes through the second refrigerant passage 11, flows out of the heat storage container 3, and merges with the refrigerant flowing in the third refrigerant passage 15. Further, the return fuel whose temperature has decreased in the heat storage container 3 flows into the fuel tank 4. Thus, since the temperature of the return fuel flowing into the fuel tank 4 is lowered, the temperature rise in the fuel tank 4 is suppressed and the volatilization of the fuel is suppressed.

  In the fourth refrigerant passage 18, the solenoid valve 22 controls the refrigerant flow state based on a signal from the ECU 24. When the solenoid valve 22 is open, the refrigerant flows through the fourth refrigerant passage 18 and warms the air blown into the room by the heater 23. The refrigerant that has passed through the heater 23 merges with the refrigerant that flows through the third refrigerant passage 15. On the other hand, when the solenoid valve 22 is closed, the flow of the refrigerant in the fourth refrigerant passage 18 is stopped. The ECU 24 determines whether the electromagnetic valve 22 is open or closed based on information on the indoor heating set temperature and the refrigerant temperature, and sends a control signal to the electromagnetic valve 22.

  As described above, during the operation after the warm-up of the engine 2 is completed, heat is transferred from the high-temperature return fuel to the refrigerant in the heat storage container 3. After the heat exchange is performed in this way, when the engine 2 is stopped, the ECU 24 stops the electric pump 19. Thereby, the flow of the refrigerant in the first refrigerant passage 10 is stopped. For this reason, the refrigerant stays in the heat storage container 3. Since the heat storage container 3 is excellent in heat retaining properties, the refrigerant is maintained in a high temperature state until the next start of the engine 2.

  Next, a case where the engine 2 is started from a cold state will be described. Before the engine 2 is started, the temperature of the refrigerant in the water jacket 13 and the third refrigerant passage 15 is lower than the temperature at which it is determined that the warm-up is completed. For this reason, the thermostat 16 forms a path so that the refrigerant can flow to the first refrigerant path 10 and the fourth refrigerant path 18.

  Before the engine 2 is started, for example, when the ignition is turned on, the ECU 24 drives the electric pump 19. Thereby, the refrigerant in the first refrigerant passage 10 flows into the heat storage container 3 by the pressure pumping of the electric pump 19. When the refrigerant flows in from the first refrigerant passage 10, the refrigerant in the heat storage container 3 flows out to the second refrigerant passage 11. Since the refrigerant in the heat storage container 3 is kept warm, the temperature of the refrigerant passing through the second refrigerant passage 11 is high. Such a refrigerant flows into the water jacket 13 via the third refrigerant passage 15. For this reason, the engine main body 12 is warmed from the high-temperature refrigerant, and warm-up is promoted.

  The waste heat recovery apparatus 1 allows the engine 2 to start after a predetermined time has elapsed since the drive of the electric pump 19 was started. As a result, the water pump 14 is operated, and the refrigerant flows through the water jacket 13 and the third refrigerant passage 15. Further, the circulation of the fuel is started, and the return fuel flows from the injectors 9 a, 9 b, 9 c, 9 d and the common rail 5 into the return fuel passage 8. In the heat storage container 3, the return fuel passing through the return fuel passage 8 and the refrigerant exchange heat. That is, the refrigerant in the heat storage container 3 is given heat from the high-temperature return fuel, and the temperature rises. Thus, since the refrigerant whose temperature has risen flows into the water jacket 13 via the second refrigerant passage 11 and the third refrigerant passage 15, warming up of the engine body 12 is further promoted.

  Further, during such warming of the engine 2, in the fourth refrigerant passage 18, the ECU 24 determines whether the electromagnetic valve 22 is open or closed based on information on the indoor heating set temperature and the refrigerant temperature. Then, the circulation state of the refrigerant is changed.

  As described above, the waste heat recovery apparatus 1 imparts waste heat from the high-temperature return fuel returned to the fuel tank 4 to the refrigerant in the heat storage container 3 during operation of the engine 2 to store heat. The waste heat recovery apparatus 1 uses the heat stored in this way for warming up the engine body 12 when the engine 2 is started, and effectively uses it. Thereby, the waste heat recovery apparatus 1 efficiently converts the heat obtained from the fuel and reduces the heat released to the outside.

  Next, a second embodiment of the present invention will be described. FIG. 2 is an explanatory diagram showing a schematic configuration of the engine 2 in which the waste heat recovery apparatus 31 of this embodiment is incorporated. The waste heat recovery apparatus 31 of the present embodiment has the same configuration as the waste heat recovery apparatus 1 of the first embodiment. However, the waste heat recovery apparatus 31 of the present embodiment is different from the waste heat recovery apparatus 1 of the first embodiment in that it includes a first bypass passage 32 that bypasses the heat storage container 3.

  In the waste heat recovery device 31, the first three-way valve 33 is disposed on the upstream side of the heat storage container 3 in the return fuel passage 8. One end of the first bypass passage 32 is connected to the first three-way valve 33. The other end of the first bypass passage 32 joins the return fuel passage 8 between the heat storage container 3 and the fuel tank 4. The first three-way valve 33 is a switching valve that switches between a path through which return fuel flows along the return fuel passage 8 and a path through which return fuel flows through the first bypass passage 32. A fuel cooler 34 corresponding to the cooler of the present invention is disposed in the first bypass passage 32. The fuel cooler 34 is provided with a fifth refrigerant passage 35 through which the refrigerant flows, and is configured such that the refrigerant flowing through the fifth refrigerant passage 35 and the return fuel flowing through the first bypass passage 32 exchange heat. ing. The fifth refrigerant passage 35 merges with the third refrigerant passage 15 on the upstream side and the downstream side of the radiator 17, and the refrigerant cooled by the radiator 17 circulates therethrough. Such a fuel cooler 34 can further cool the return fuel as compared with the heat storage container 3.

  In addition, the waste heat recovery device 31 includes a first temperature sensor 36 on the upstream side of the first three-way valve 33 in the return fuel passage 8. Further, the first temperature sensor 36 is electrically connected to the ECU 24, and temperature information of the return fuel measured by the first temperature sensor 36 is transmitted to the ECU 24. Further, the first three-way valve 33 and the ECU 24 are electrically connected, and the ECU 24 changes the path state to the first three-way valve 33 based on the temperature information of the return fuel measured by the first temperature sensor 36. Send a signal to switch. Thus, the 1st three-way valve 33 and ECU24 comprise the 1st switching means of this invention. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  Next, the operation of the waste heat recovery apparatus 31 will be described while explaining the control flow of the ECU 24. FIG. 3 is a flowchart showing a control flow of the ECU 24 in the waste heat recovery apparatus 31.

  In step S1, the ECU 24 determines whether or not the engine 2 has been warmed up. If the ECU 24 determines YES in step S1, that is, if the warm-up of the engine 2 has been completed, the ECU 24 proceeds to step S2.

  In step S2, the ECU 24 stops the electric pump 19. Thereby, the circulation of the refrigerant in the first refrigerant passage 10 is blocked, and the refrigerant in the heat storage container 3 stays. When the ECU 24 finishes the process of step S2, the ECU 24 proceeds to step 3.

  In step S3, the ECU 24 determines whether or not the temperature Tfrt of the return fuel flowing through the return fuel passage 8 is equal to or lower than the reference temperature T1. The temperature Tfrt is temperature information measured by the first temperature sensor 36. The reference temperature T1 is a temperature in a range that does not damage the fuel system, and the reference temperature T1 is a preset temperature. Here, the fuel system indicates the fuel passage 7, the return fuel passage 8, and the devices through which the fuel flows. If the ECU 24 determines YES in step S3, that is, if the return fuel temperature Tfrt is equal to or lower than the reference temperature T1, the ECU 24 proceeds to step S4.

  In step S4, the ECU 24 controls the first three-way valve 33 to switch to a path through which the return fuel flows along the return fuel passage 8, that is, a path through which the return fuel flows into the heat storage container 3. For this reason, heat exchange is performed between the return fuel and the refrigerant in the heat storage container 3, the temperature of the return fuel decreases, and the temperature of the refrigerant in the heat storage container 3 increases. The ECU 24 returns after completing the process of step S4.

  On the other hand, if the ECU 24 determines NO in step S3, that is, if the return fuel temperature Tfrt is higher than the reference temperature T1, the process proceeds to step S5. In step S <b> 5, the ECU 24 sets the path of the first three-way valve 33 as a path for the return fuel to flow into the first bypass path 32. When the temperature Tfrt of the return fuel is higher than the reference temperature T1, the heat storage container 3 cannot sufficiently lower the temperature of the return fuel. When such return fuel flows into the fuel tank 4, the temperature of the fuel in the fuel tank 4 rises. For this reason, the return fuel is sent to the fuel cooler 34 having a higher cooling capacity than the heat storage container 3, and the temperature of the fuel in the fuel tank 4 is prevented from rising. The ECU 24 returns after completing the process of step S5.

  By the way, when the ECU 24 determines NO in step S1, that is, when the warm-up of the engine 2 has not been completed, the processing of step S6 and step S7 is performed. The ECU 24 drives the electric pump 19 in step S6. In step S7, the ECU 24 sets the path of the first three-way valve 33 as a path through which the return fuel flows along the return fuel passage 8, that is, a path through which the return fuel flows into the heat storage container 3. When the warm-up of the engine 2 is not completed, heat exchange between the refrigerant and the return fuel in the heat storage container 3 is promoted, and the warm-up of the engine 2 is promoted. Note that the order of step S6 and step S7 may be interchanged. The ECU 24 returns after completing the process of step S6.

  As described above, when the temperature of the return fuel exceeds the reference temperature, the waste heat recovery device 31 sends the return fuel to the fuel cooler 34 having a higher cooling capacity than the heat storage container 3 to protect the fuel system.

  Next, Embodiment 3 of the present invention will be described. FIG. 4 is an explanatory diagram showing a schematic configuration of the engine 2 in which the waste heat recovery apparatus 41 of this embodiment is incorporated. The waste heat recovery apparatus 41 of the present embodiment has the same configuration as the waste heat recovery apparatus 1 of the first embodiment. The waste heat recovery apparatus 41 of this embodiment is different from the waste heat recovery apparatus 1 of Embodiment 1 in that it includes a second bypass passage 42 that bypasses the fuel tank 4.

  The waste heat recovery device 41 includes a second three-way valve 43 on the downstream side of the heat storage container 3 in the return fuel passage 8. One end of a second bypass passage 42 is connected to the second three-way valve 43. The other end of the second bypass passage 42 joins the fuel passage 7 between the fuel tank 4 and the fuel pump 6. The second three-way valve 43 is a switching valve that switches between a path through which return fuel flows along the return fuel passage 8 and a path through which return fuel flows through the second bypass passage 42.

  Further, the waste heat recovery apparatus 41 includes a second temperature sensor 44 and a third temperature sensor 45. The second temperature sensor 44 is disposed between the heat storage container 3 and the second three-way valve 43 in the return fuel passage 8. The third temperature sensor 45 is disposed in the fuel tank 4. Further, each of the second temperature sensor 44 and the third temperature sensor 45 is electrically connected to the ECU 24, and the temperature information of the return fuel passing through the heat storage container 3 measured by the second temperature sensor 44, the third The temperature information of the fuel in the fuel tank 4 measured by the temperature sensor 45 is transmitted to the ECU 24. Further, the second three-way valve 43 is electrically connected to the ECU 24, and the ECU 24 determines whether the second three-way valve 43 is based on temperature information measured by the second temperature sensor 44 and the third temperature sensor 45. A signal for switching the path state is transmitted. Thus, the second three-way valve 43 and the ECU 24 constitute the second switching means of the present invention. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  Next, the operation of the waste heat recovery apparatus 41 will be described while explaining the control flow of the ECU 24. FIG. 5 is a flowchart showing a control flow of the ECU 24 in the waste heat recovery apparatus 41.

  In step S11, the ECU 24 determines whether or not the temperature Tf_pmp_out of the return fuel that has passed through the fuel pump 6 is equal to or lower than the reference temperature T2. The temperature Tf_pmp_out is the temperature of the fuel injected into the cylinder predicted from the temperature information measured by the third temperature sensor 45. The reference temperature T2 is a preset temperature. For example, when the temperature of the fuel injected into the cylinder is equal to or higher than the reference temperature T2, the discharge of unburned fuel is reduced. The reference temperature T2 is such a fuel temperature threshold. If the ECU 24 determines YES in step S11, that is, if the temperature Tf_pmp_out of the fuel injected into the cylinder is equal to or lower than the reference temperature T2, the process proceeds to step S12. Note that the temperature acquired for predicting the temperature Tf_pmp_out of the fuel injected into the cylinder may not be the temperature of the fuel in the fuel tank 4. For example, it can be predicted from the temperature of the fuel flowing from the fuel pump 6 to the common rail 5. Moreover, the temperature acquired in this way should just be what can predict the temperature Tf_pmp_out of the fuel injected in a cylinder.

  In step S12, the ECU 24 determines whether or not the temperature Tf_pmp_in of the return fuel that has passed through the heat storage container 3 is equal to or lower than the reference temperature T3. The temperature Tf_pmp_in is temperature information measured by the second temperature sensor 44. The reference temperature T3 is a range in which the fuel injected into the cylinder does not adversely affect the common rail 5, the fuel passage 8, the injectors 9a, 9b, 9c, 9d, the engine body 12, and the like (hereinafter referred to as “injection system”). Temperature. Such a reference temperature T3 is a preset temperature. If the ECU 24 determines YES in step S12, that is, if the temperature Tf_pmp_in of the return fuel that has passed through the heat storage container 3 is equal to or lower than the reference temperature T3, the process proceeds to step S13.

  In step S <b> 13, the ECU 24 sets the route of the second three-way valve 43 as a route through which return fuel flows into the second bypass passage 42. When the ECU 24 performs the process of step S13, the fuel injected into the cylinder does not reach a temperature at which good combustion is performed. On the other hand, the return fuel in the heat storage container 3 is maintained in a heat-retaining state and is in a higher temperature than the fuel in the fuel tank 4. For this reason, the ignitability of the fuel is improved by introducing the fuel in the heat storage container 3 into the cylinder. Thereby, generation | occurrence | production of the unburned fuel in the engine 2 is suppressed. Moreover, since the fuel in the heat storage container 3 is not high enough to adversely affect the injection system, good combustion is performed. The ECU 24 returns after completing the process of step S13.

  When the ECU 24 determines NO in step S11, that is, when the temperature Tf_pmp_out of the fuel injected into the cylinder is higher than the reference temperature T2, the process proceeds to step S14. In step S <b> 14, the ECU 24 sets the path of the second three-way valve 43 as a path through which the return fuel flows along the return fuel passage 8, that is, a path through which the return fuel flows into the fuel tank 4. When the ECU 24 determines NO in step S11, the fuel in the fuel tank 4 is at a temperature at which combustion can be satisfactorily performed in the cylinder. For this reason, the fuel in the fuel tank 4 is supplied to the injection system.

  Further, if the ECU 24 determines NO in step S12, that is, if the temperature Tf_pmp_in of the return fuel that has passed through the heat storage container 3 is higher than the reference temperature T3, the process proceeds to step S14. When the ECU 24 determines NO in step S12, if the return fuel in the heat storage container 3 is supplied to the injection system, the injection system may be damaged. For this reason, when the return fuel in the heat storage container 3 is at such a high temperature, the supply of the return fuel in the heat storage container 3 directly to the injection system is stopped. The ECU 24 returns after completing the process of step S14.

  As described above, when the fuel in the fuel tank 4 is at a low temperature, such as when the engine 2 is started, the fuel in the heat storage container 3 maintained at a higher temperature than in the fuel tank 4 is used for injection. Thus, good combustion can be obtained. Thereby, the startability of the engine 2 is improved and the atmospheric discharge of unburned fuel is suppressed.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

  For example, the waste heat recovery apparatus 1 according to the first embodiment may include a heat storage container 50 filled with a heat storage agent instead of the heat storage container 3. FIG. 6 is an explanatory diagram showing a schematic configuration of the heat storage container 50. The heat storage container 50 is a tank having heat retaining properties, and a heat storage agent 51 is filled therein. Inside the heat storage container 50, an in-container refrigerant passage 52 having one end connected to the first refrigerant passage 10 and the other end connected to the second refrigerant passage 11 is provided. A part of the return fuel passage 8 is drawn into the heat storage container 50. In the heat storage container 50, the refrigerant passing through the in-container refrigerant passage 52 and the heat storage agent 51 perform heat exchange. At this time, the refrigerant is supplied with heat from the heat storage agent 51. In the heat storage container 50, the return fuel passing through the return fuel passage 8 exchanges heat with the heat storage agent 51. At this time, the return fuel supplies heat to the heat storage agent 51. Other configurations are the same as those of the first embodiment, and the same operations and effects are achieved.

  Furthermore, the waste heat recovery apparatus of the present invention can apply the heat stored in the heat storage means to the heater that warms the room. FIG. 7 is an explanatory view showing a schematic configuration of the engine 2 including such a waste heat recovery device 61. The waste heat recovery device 61 has substantially the same configuration as the waste heat recovery device 1 of the first embodiment. The waste heat recovery device 61 is different from the first refrigerant passage 10 and the second refrigerant passage 11 in that it includes a loop-like sixth refrigerant passage 62 through which the refrigerant in the heat storage container 3 circulates. This is different from the waste heat recovery apparatus 1. Both ends 62 a and 62 b of the sixth refrigerant passage 62 through which the refrigerant flows are inserted into the heat storage container 3 from the bottom surface 3 a side of the heat storage container 3 toward the inside of the heat storage container 3. The refrigerant flows into the heat storage container 3 from one end 62a of the sixth refrigerant passage 62 and flows out from the other end 62b. In the sixth refrigerant passage 62, the second check valve 21, the electromagnetic valve 22, the heater 23, the electric pump 19, and the first check valve 20 are sequentially arranged in the direction in which the refrigerant flows from the side closer to the heat storage container 3. Yes. In addition, since the other structure is the same as Example 1, about the component same as Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted. In the waste heat recovery device 61, in the heat storage container 3, the return fuel passing through the return fuel passage 8 and the refrigerant in the heat storage container 3 exchange heat. When the engine 2 is operated and the return fuel becomes high temperature, the refrigerant in the heat storage container 3 is also warmed. The refrigerant thus warmed is configured to warm the air blown into the room in the heater 23.

  In addition, the waste heat recovery apparatus of the present invention is not limited to the return fuel from the injector and the common rail, but can recover and utilize the waste heat with the same configuration as long as the return fuel has recoverable thermal energy. Can do. That is, the waste heat recovery apparatus of the present invention can be provided not only in a diesel engine but also in a gasoline engine.

It is explanatory drawing which showed schematic structure of the diesel engine incorporating the waste heat recovery apparatus of Example 1. FIG. It is explanatory drawing which showed schematic structure of the diesel engine incorporating the waste heat recovery apparatus of Example 2. FIG. 6 is a flowchart illustrating a control flow of an ECU in the waste heat recovery apparatus according to the second embodiment. It is explanatory drawing which showed schematic structure of the diesel engine incorporating the waste heat recovery apparatus of Example 3. FIG. 6 is a flowchart showing a control flow of an ECU in the waste heat recovery apparatus of Embodiment 3. It is explanatory drawing which showed schematic structure of the thermal storage container with which the thermal storage agent with which the other waste heat recovery apparatus of this invention is provided was filled. Furthermore, it is the other waste heat recovery apparatus of this invention, Comprising: It is explanatory drawing which showed schematic structure of the diesel engine provided with the waste heat recovery apparatus which provides heat to the heater which warms a room | chamber interior.

Explanation of symbols

1, 31, 41, 61 Waste heat recovery device 2 Engine 3, 50 Heat storage container 4 Fuel tank 7 Fuel passage 8 Return fuel passage 10 First refrigerant passage 11 Second refrigerant passage 12 Engine body 13 Water jacket 15 Third refrigerant passage 16 Thermostat 17 Radiator 18 Fourth refrigerant passage 19 Electric pump 22 Solenoid valve 23 Heater 24 ECU
32 First bypass passage 33 First three-way valve 34 Fuel cooler 35 Fifth refrigerant passage 36 First temperature sensor 42 Second bypass passage 43 Second three-way valve 44 Second temperature sensor 45 Third temperature sensor 51 Heat storage agent 52 Refrigerant in container Passage 62 Sixth refrigerant passage

Claims (8)

A return fuel passage through which return fuel circulates;
A heat storage means for storing waste heat of the return fuel;
An exhaust heat recovery device for an engine characterized by comprising: The engine waste heat recovery apparatus according to claim 1,
An engine waste heat recovery apparatus comprising a refrigerant passage through which heat is applied in the heat storage means and the refrigerant circulating in the engine flows. The engine waste heat recovery apparatus according to claim 1,
The heat storage means is provided with heat, and includes a refrigerant passage through which a refrigerant circulating in the engine flows.
The engine waste heat recovery apparatus, wherein the heat storage means is a heat storage container in which the return fuel passage and the refrigerant passage are drawn and a heat storage agent is filled therein. The engine waste heat recovery apparatus according to claim 1,
The heat storage means is provided with heat, and includes a refrigerant passage through which a refrigerant circulating in the engine flows.
The waste heat recovery apparatus for an engine, wherein the heat storage means is a heat storage container that stores therein a refrigerant flowing through the refrigerant passage and draws the return fuel passage. The engine waste heat recovery apparatus according to claim 1,
An engine waste heat recovery apparatus comprising cooling means for cooling the return fuel based on temperature information of the return fuel. The engine waste heat recovery apparatus according to claim 1,
Cooling means for cooling the return fuel based on temperature information of the return fuel;
The cooling means is
A first bypass passage through which the return fuel bypasses the heat storage means;
First switching means for controlling a flow state of the return fuel to the first bypass passage based on temperature information of the return fuel;
A cooler for cooling the return fuel passing through the first bypass passage;
An exhaust heat recovery device for an engine characterized by comprising: The engine waste heat recovery apparatus according to claim 1,
An engine waste heat recovery apparatus comprising a second bypass passage through which the return fuel that has passed through the heat storage means bypasses the fuel tank. The engine waste heat recovery apparatus according to claim 1,
A second bypass passage through which the return fuel that has passed through the heat storage means bypasses the fuel tank;
Second switching means for controlling the flow state of the return fuel to the second bypass passage based on the temperature of the return fuel that has passed through the heat storage means and the temperature of the fuel injected into the cylinder;
An exhaust heat recovery device for an engine characterized by comprising:

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