JP2011196345A - Exhaust heat recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device which shortens catalyst warm-up time without requiring complicated structure of an exhaust pipe and control over a cooling water flow rate, in the exhaust heat recovery device including an exhaust heat recovery unit provided upstream of an exhaust gas flow from a catalyst in the exhaust pipe.SOLUTION: In this exhaust heat recovery device arranged upstream of the exhaust gas flow from the catalyst 12 in the exhaust pipe 11, a valve mechanism 150 adjusting the passage area of a return passage 134 is provided in the return passage 134 returning a working medium condensed by a condenser 130 to an evaporation section 110. A control section 160 closes the return passage 134 by the valve mechanism 150 when an internal combustion engine 10 is stopped or immediately before stopping or immediately after stopping, and maintains the closed state of the return passage 134 until the internal combustion engine is started next time and temperature Tc of the catalyst 12 reaches a predetermined catalyst temperature Tc1.

Description

  The present invention relates to an exhaust heat recovery device that recovers exhaust heat of an exhaust gas of an internal combustion engine using a heat exchanger and uses it for heating cooling water of the internal combustion engine. For example, the present invention is used for a vehicle equipped with an internal combustion engine. It is preferable.

  As a conventional exhaust heat recovery device, for example, one disclosed in Patent Document 1 is known. In Patent Document 1, a heat exchanger is provided on the upstream side of an exhaust flow of a catalyst (catalytic converter) disposed in an exhaust pipe, and the heat of the exhaust is converted into cooling water in an engine cooling circuit by this heat exchanger. It has come to be collected. Further, in Patent Document 1, a bypass pipe that bypasses the heat exchanger is provided in the exhaust pipe, and when the exhaust temperature is equal to or lower than the critical operating temperature of the catalyst, the exhaust is passed through the bypass pipe, The catalyst is not recovered into the cooling water, that is, priority is given to warming up the catalyst by suppressing the temperature drop of the exhaust gas by the heat exchanger.

  Further, Patent Document 2 discloses an exhaust heat recovery device that is disposed in the middle of an exhaust pipe, exchanges heat between engine cooling water and exhaust, and has a catalyst that is warmed up by exhaust, and cooling water. An exhaust heat recovery device including an electric pump for circulation is described. In Patent Document 2, when the catalyst is warmed up after the engine is started, the circulation flow rate of the cooling water to the exhaust heat recovery device is set to a predetermined amount or less to suppress the recovery of the exhaust heat to the cooling water side. Priority is given to warming up the catalyst.

Japanese Patent Laid-Open No. 11-2182020 JP 2008-190437 A

  However, in the exhaust heat recovery apparatus of Patent Document 1, exhaust is bypassed with respect to the heat exchanger, but the structure of the exhaust pipe upstream of the catalyst is complicated by providing the bypass pipe. Further, the heat capacity on the upstream side of the catalyst also increases, and the heat dissipation loss of the exhaust on the upstream side increases, so the time required for warming up the catalyst becomes longer.

  In the exhaust heat recovery device of Patent Document 2, the cooling water circulation amount to the exhaust heat recovery device is set to a predetermined amount or less, but heat exchange between the exhaust gas and the cooling water cannot be stopped. The temperature is lowered, and the time required for warming up the catalyst becomes longer.

  In view of the above problems, the object of the present invention is to provide an exhaust heat recovery device upstream of the catalyst in the exhaust pipe, so that the complicated structure of the exhaust pipe and the control of the flow rate of the cooling water are not required. An object of the present invention is to provide an exhaust heat recovery device that can shorten the warm-up time.

  In order to achieve the above object, the present invention employs the following technical means.

In the first aspect of the invention, a catalyst (12) for purifying the exhaust gas of the internal combustion engine (10) is disposed in the middle of the exhaust pipe (11) of the internal combustion engine (10), and the exhaust pipe (11). An exhaust heat recovery device provided upstream of the exhaust flow from the catalyst (12).
An evaporation section (110) for evaporating an internal working medium by heat of exhaust;
A condensing unit (130) for radiating heat of the working medium flowing from the evaporation unit (110) to the cooling water of the internal combustion engine (10) to condense the working medium;
A return passage (134) for returning the condensed working medium to the evaporation section (110);
A valve mechanism (150) provided in the return passage (134) for adjusting the passage area of the return passage (134);
When the internal combustion engine (10) is stopped, immediately before the stop, or immediately after the stop, the return mechanism (134) is closed by the valve mechanism (150), and the internal combustion engine (10) is started next time. And a control unit (160) for maintaining the closed state of the return passage (134) until the temperature (Tc) of the catalyst (12) reaches a predetermined catalyst temperature (Tc1) set in advance.

  According to the present invention, when the internal combustion engine (10) is stopped, immediately before stopping, or immediately after stopping, the return passage (134) is closed, so that the working medium condensed in the condensing unit (130) is Without being returned to the evaporation section (110), it is stored in the condensation section (130). In addition, even after the internal combustion engine (10) is stopped, the working medium in the evaporation section (110) is evaporated by the residual heat of the exhaust gas and flows into the condensation section (130).

  Therefore, when the internal combustion engine (10) is started next time, the state where there is no liquid-phase working medium in the evaporation section (110) can be set, and the condensation section (130) to the evaporation section (110). It is possible to prevent reflux of the working medium. Then, until the internal combustion engine (10) is started and the temperature (Tc) of the catalyst (12) reaches a predetermined catalyst temperature (Tc1), the internal circulation of the working medium by evaporation and condensation is stopped, that is, exhaust and Since the heat exchange with the cooling water can be stopped and the temperature drop of the exhaust gas can be eliminated, the catalyst (12) can be warmed up in a short time.

In the invention according to claim 2, the valve mechanism (150) is an electric drive valve (150),
The return passage (134) is closed when the energization is stopped by the control unit (160), and the return passage (134) is opened when the energization is performed by the control unit (160). It is a feature.

  According to the present invention, when the internal combustion engine (10) is stopped or just before the stop, the controller (160) may stop energization of the valve mechanism (150) in order to close the return passage (134). become. Therefore, while the internal combustion engine (10) is stopped, and until the next time the internal combustion engine (10) is started and the catalyst (12) reaches a predetermined catalyst temperature (Tc1), electric power is used to close the return passage (134). We can cope without using.

  In the invention according to claim 3, when the temperature (Tc) of the catalyst (12) reaches a predetermined catalyst temperature (Tc1), the controller (160) opens the return passage (134) by the valve mechanism (150). It is characterized by that.

  According to the present invention, by opening the return passage (134), the working medium stored in the condenser (130) returns to the evaporator (110), and further between the evaporator (110) and the condenser (130). Since the working medium can be circulated, it is possible to heat the cooling water utilizing the heat of the original exhaust, that is, to warm up the internal combustion engine (10). Here, since the exhaust heat recovery is performed on the upstream side of the catalyst (12), when exhaust is performed on the downstream side, exhaust without temperature decrease is used as compared with the case where the exhaust temperature is decreased by the catalyst. This makes it possible to recover the exhaust heat by effectively using the heat of the exhaust, and heat the cooling water in a short time.

  In the invention according to claim 4, when the control part (160) opens the return passage (134) and the cooling water temperature (Tw) is higher than a predetermined cooling water temperature (Tw1), The return passage (134) is changed to the closing side by the valve mechanism (150), and when the cooling water temperature (Tw) is lower than the predetermined cooling water temperature (Tw1), the return passage (134) is changed to the opening side. It is characterized by that.

  According to this invention, when the cooling water temperature (Tw) is higher than the predetermined cooling water temperature (Tw1), the valve mechanism (150) changes the return passage (134) to the closing side, thereby 110) and the condenser (130) can be circulated in a reduced amount, so that heat recovery of the exhaust can be suppressed and an increase in the coolant temperature (Tw) can be suppressed.

  Further, when the cooling water temperature (Tw) is lower than the predetermined cooling water temperature (Tw1), the valve mechanism (150) is changed to open the return passage (134), thereby condensing the evaporator (110) and the condensation. Since the circulation amount of the working medium between the sections (130) can be increased, the heat recovery of the exhaust can be promoted, and the cooling water temperature (Tw) can be raised. Therefore, the cooling water temperature (Tw) can be appropriately maintained.

  As in the fifth aspect of the present invention, in the exhaust heat recovery apparatus, the evaporation section (110), the condensation section (130), and the return passage (134) form a loop heat pipe.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

It is a schematic diagram which shows the mounting state to the vehicle of the exhaust heat recovery apparatus in 1st Embodiment. It is sectional drawing which shows a heat exchange part. It is a flowchart which shows the control content which a control part performs. It is a time chart which shows the operating state of each part.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly indicate that the combination is possible in each embodiment, but also a combination of the embodiments even if they are not clearly specified unless there is a problem with the combination. It is also possible.

(First embodiment)
The exhaust heat recovery apparatus 100 according to the first embodiment of the present invention is applied to a vehicle (automobile) using the engine 10 as a driving source for traveling. The exhaust heat recovery device 100 is disposed in the exhaust pipe 11 and the heater circuit 30 of the engine 10. A specific configuration will be described below with reference to FIGS. FIG. 1 is a schematic view showing a state where the exhaust heat recovery apparatus 100 is mounted on a vehicle, and FIG. 2 is a cross-sectional view showing the heat exchanging portion 101.

  As shown in FIG. 1, the engine 10 is a water-cooled internal combustion engine, and has an exhaust pipe 11 through which exhaust gas after combustion of fuel is discharged. A catalyst 12 is provided in the middle of the exhaust pipe 11. The catalyst 12 purifies exhaust gas, and is formed by adding a catalyst substance to a prismatic member (monolith) made of, for example, a ceramic material. Further, the catalyst 12 is provided with a temperature sensor 12a for detecting the temperature of the catalyst, and the catalyst temperature Tc (temperature signal) detected by the temperature sensor 12a is output to the control unit 160 described later. ing.

  In addition, the engine 10 outputs an operation state signal indicating the operation state of the engine 10 to the control unit 160 described later. Examples of the operating state signal include a fuel injection amount, an intake air amount, an engine speed, and the like. Here, the fuel injection amount is used as the operation state signal. Upon receiving the fuel injection amount signal, the control unit 160 determines that the engine 10 is in an operating state and that the output of the engine 10 is increased with an increase in the fuel injection amount signal. If is zero, the engine 10 is determined to be in a stopped state.

  The engine 10 includes a radiator circuit 20 through which engine cooling water (hereinafter referred to as cooling water) for cooling the engine 10 circulates, and a heater circuit 30 through which cooling water (hot water) circulates as a circuit different from the radiator circuit 20. have.

  The radiator circuit 20 is a circuit in which the coolant is circulated so that the coolant flows out from the outflow portion of the engine 10 and returns to the inflow portion. A radiator 21 is provided in the middle of the radiator circuit 20, and the radiator 21 cools cooling water circulated by a water pump 22 provided at the outflow portion of the engine 10 by heat exchange with outside air. In the radiator circuit 20, a thermostat 23 is provided on the downstream side of the cooling water flow of the radiator 21. The thermostat 23 adjusts the amount of cooling water flowing through the radiator circuit 20 and a heater circuit 30 described later according to the temperature of the cooling water. Particularly at the time of warming up, the thermostat 23 reduces the amount of cooling to the radiator circuit 20 side, and conversely, the amount of cooling water to the heater circuit 30 side is increased to promote warming up. That is, overcooling of the cooling water by the radiator 21 is prevented. Further, a water temperature sensor (not shown) for detecting the temperature of the cooling water is provided on the outlet side of the water pump 22 of the radiator circuit 20, and the cooling water temperature Tw (temperature signal) detected by the water temperature sensor is The data is output to a control unit 160 described later.

  The heater circuit 30 is a circuit that branches from between the water pump 22 and the radiator 21 in the radiator circuit 20 and is connected to the thermostat 23. Like the radiator circuit 20, the cooling water (hot water) is circulated by the water pump 22. It has come to be. A heater core 31 as a heating heat exchanger is provided in the middle of the heater circuit 30. Cooling water (hot water) circulating through the heater circuit 30 is circulated through the heater core 31. The heater core 31 is disposed in an air conditioning case of an air conditioning unit (not shown), and heats the conditioned air blown by the blower by heat exchange with hot water. And in the heater circuit 30, the water tank 140 (condensing part 130) of the exhaust heat recovery apparatus 100 mentioned later is connected to the downstream of the cooling water flow of the heater core 31.

  As shown in FIGS. 1 and 2, the exhaust heat recovery apparatus 100 includes a heat exchange unit 101, a valve mechanism 150, a control unit 160, and the like.

  The heat exchange unit 101 includes an evaporation unit 110, a duct unit 120, a condensing unit 130, and a water tank 140. The evaporating unit 110 and the condensing unit 130 are annularly connected by a communication path 115 and a return path 134, and the heat exchanging unit 101 forms a loop heat pipe. The heat pipe is provided with a sealing portion (not shown). The heat pipe is evacuated (depressurized) from the sealing portion, and after the working medium is sealed, the sealing portion is sealed. Here, water is used as the working medium. The boiling point of water is 100 ° C. at 1 atmosphere, but the boiling point is 5 to 10 ° C. because the inside of the heat pipe 101 is depressurized (eg, 0.01 atmosphere). As the working medium, alcohol, fluorocarbon, chlorofluorocarbon or the like may be used in addition to water.

  Each member (hereinafter described) constituting the exhaust heat recovery apparatus 100 is made of a stainless material having high corrosion resistance, and is integrated by a brazing material provided at a contact portion or a fitting portion after each member is assembled. It is brazed.

  The evaporation unit 110 includes a tube 111, fins 112, a lower tank unit 113, and an upper tank unit 114. The tubes 111 are elongated tube members having a flat cross section, and a plurality of tubes 111 are arranged with a predetermined tube pitch in the left-right direction in FIG.

  The fins 112 are heat exchange members interposed between the tubes 111 arranged in a plurality as described above, and are joined to the outer wall surfaces (surfaces) of the tubes 111. The fin 112 expands the heat exchange area with the exhaust gas, and here is a corrugated fin formed from a thin strip plate material into a corrugated shape by roller processing.

  The lower tank portion 113 and the upper tank portion 114 are both formed as flat container bodies, and are disposed on both ends of the tube 111 in the longitudinal direction. Tube holes (not shown) are formed at positions corresponding to the tubes 111 of the tank portions 113 and 114. The longitudinal ends of the plurality of tubes 111 are joined to the tube holes of the tank portions 113 and 114, respectively, and the plurality of tubes 111 communicate with the tank portions 113 and 114.

  The duct portion 120 is a cylindrical body having a rectangular cross section, and exhaust gas flows inside. An evaporation unit 110 is accommodated in the duct unit 120. The evaporating unit 110 is accommodated in the duct unit 120 so that the direction in which a plurality of tubes 111 are arranged and the direction orthogonal to the longitudinal direction of the tubes 111 is the exhaust flow direction. A gap is not formed as much as possible between the outer peripheral surface of the evaporation unit 110 and the inner peripheral surface of the duct unit 120 so that the exhaust gas passes through the portion where the tubes 111 and the fins 112 are disposed.

  Similar to the evaporation unit 110, the condensing unit 130 includes a tube 131 whose longitudinal direction is directed in the vertical direction, and both longitudinal end portions of the tube 131 are joined to the upper tank unit 132 and the lower tank unit 133. Is formed. The tube 131 communicates with the tank portions 132 and 133. The said condensation part 130 is accommodated in the water tank 140 mentioned later.

  The water tank 140 is an elongated container body formed along the longitudinal direction of the tube 131, and a cooling water introduction pipe 141 for introducing cooling water into the inside is provided on one side wall in the longitudinal direction. A cooling water discharge pipe 142 that discharges cooling water to the outside is provided on the other side wall in the longitudinal direction.

  The upper tank part 114 of the evaporation part 110 and the upper tank part 132 of the condensing part 130 are connected with each other by a communication path 115 made of a pipe member. The communication passage 115 extends outward from one end of the upper tank portion 114 in the longitudinal direction so as to penetrate the duct portion 120, and further penetrates the water tank 140 in the longitudinal direction of the upper tank portion 132. Connected to one end.

  Further, the lower tank part 133 of the condensing unit 130 and the lower tank part 113 of the evaporation unit 110 are communicated with each other by a return passage 134 made of a pipe member. The return passage 134 extends from the inside of the lower tank portion 133 to the outside so as to penetrate the water tank 140, and further passes through the duct portion 120 and is connected to one end portion in the longitudinal direction of the lower tank portion 113. Has been.

  The valve mechanism 150 is an electric drive valve that adjusts the passage area of the return passage 134 and is provided in the lower tank portion 133 of the condensing unit 130. The valve body 151 of the valve mechanism 150 is disposed in the return passage 134. The valve mechanism 150 is in a fully closed state in which the passage area of the return passage 134 is made zero by controlling the valve opening degree of the valve body 151 by the control unit 160 described later, and further, the passage area is reduced to the original return passage 134. In addition to the fully open state as the passage area, it is possible to form an intermediate state having an arbitrary passage area between the fully closed state and the fully open state.

  The valve mechanism 150 is a normally closed valve that fully closes the return passage 134 when energization from the control unit 160 is stopped. When energized, the valve mechanism 150 opens the return passage 134 according to the energization amount. The passage area is increased.

  The control unit 160 is a control unit that controls the valve opening degree of the valve body 151 of the valve mechanism 150 based on the operating state signal (fuel injection amount) of the engine 10, the catalyst temperature Tc, and the cooling water temperature Tw. Details of control of the valve mechanism 150 by the controller 160 will be described later.

  As described above, the exhaust heat recovery apparatus 100 is formed, and the duct portion 120 (evaporating portion 110) is interposed in the exhaust pipe 11 so as to be upstream of the exhaust flow with respect to the catalyst 12 in the exhaust pipe 11. ing. The cooling water introduction pipe 141 and the cooling water discharge pipe 142 of the water tank 140 are connected to the downstream side of the heater core 31 in the heater circuit 30, and the cooling water (hot water) of the heater circuit 30 is placed in the water tank 140. Has come to circulate.

  Next, the operation of the exhaust heat recovery apparatus 100 based on the above configuration and the operation and effect thereof will be described with reference to FIGS. FIG. 3 is a flowchart showing the contents of control performed by the control unit 160, and FIG. 4 is a time chart showing the operating state of each unit.

  The control unit 160 executes the control flow shown in FIG. 3 until the engine 10 is started and stopped, and repeatedly executes this control flow every time the engine 10 is started. In the control flow shown in FIG. 3, the control unit 160 is configured to fully close the valve body of the valve mechanism 150 when the engine 10 is stopped as described later (step S140). When the engine is started, first, in step S100, the control is started while the fully closed state of the valve body 151 is maintained. The fully closed state of the valve body 151 is maintained by continuing to stop energization of the valve mechanism 150.

  When the engine 10 is started, fuel is injected into the engine 10 (FIG. 4B), and exhaust gas generated by the combustion of the fuel flows through the exhaust pipe 11 and is discharged outside the vehicle. In the meantime, the exhaust gas passes through the duct part 120 (evaporation part 110) and the catalyst 12. Further, since the temperature of the cooling water is not sufficiently increased when the engine 10 is started (FIG. 4D), the radiator circuit 20 is closed by the thermostat 23, and the cooling water is mainly used as a heater. It circulates through the circuit 30 and passes through the heater core 31 and the water tank 140 (condensing unit 130) during that time.

  When the engine 10 is started, the state of the valve body 151 that is fully closed when the engine 10 is stopped is maintained as it is by the above-described step S100 (FIG. 4 (e)). The liquid phase working medium is accumulated, and the inside of the evaporation unit 110 is in a state where all the working medium is evaporated, and there is no liquid phase working medium (FIG. 4F). The exhaust gas passes through the portion of the evaporation unit 110 where the tubes 111 and the fins 112 are disposed, but the working medium does not evaporate in the evaporation unit 110 due to the exhaust gas. Therefore, the temperature of the exhaust gas is not lowered by the latent heat of vaporization of the working medium, and the catalyst 12 on the downstream side of the evaporation unit 110 is positively heated and the temperature rises by the exhaust gas not accompanied by this temperature drop ( FIG. 4C shows a catalyst warm-up region).

  While the temperature of the catalyst 12 is increasing as described above, it is determined in step S110 whether or not the catalyst temperature Tc detected by the temperature sensor 12a is equal to or higher than a predetermined catalyst temperature Tc1. The predetermined catalyst temperature Tc1 is determined in advance as a temperature (for example, 400 ° C.) at which the catalyst 12 can exhibit an original purification function for exhaust gas. If NO is determined in step S110, steps S100 and S110 are repeated, and if it is determined that the catalyst temperature Tc is equal to or higher than the predetermined catalyst temperature Tc1, the process proceeds to step S120.

  In step S120, the valve opening degree of the valve body 151 is adjusted according to the required heat recovery amount for the cooling water. The required heat recovery amount can be dealt with, for example, based on the catalyst temperature Tc and the cooling water temperature Tw.

  Specifically, first, when the catalyst temperature Tc becomes equal to or higher than the predetermined catalyst temperature Tc1, it is assumed that the heating of the catalyst 12 is completed, and then the cooling water is effectively heated. That is, by energizing the valve mechanism 150, the valve body 151 that has been fully closed is fully opened (the beginning of heat recovery in FIG. 4E). Then, the liquid phase working medium in the condensing unit 130 is refluxed from the return passage 134 to the evaporation unit 110. In the evaporation unit 110, the liquid phase working medium evaporates due to the heat of the exhaust, and the evaporated gas phase working medium flows into the condensing unit 130 from the communication path 115. The gas phase working medium that has flowed into the condensing unit 130 is cooled and condensed by the cooling water flowing through the water tank 140. Then, the condensed liquid phase working medium returns to the evaporation unit 110 through the return passage 134. In this way, part of the heat of the exhaust is transmitted to the working medium as latent heat of vaporization, and the working medium is converted into vapor and transported from the evaporation unit 110 to the condensing unit 130 and condensed when the vapor condenses in the condensing unit 130. The cooling water released as latent heat and flowing through the water tank 140 (heater circuit 30) is positively heated (cooling water warm-up region in FIG. 4D).

  When the cooling water temperature Tw becomes equal to or higher than a predetermined cooling water temperature Tw1, the valve opening degree of the valve body 151 is reduced and the return passage 134 is changed to the closing side. The predetermined cooling water temperature Tw1 is predetermined as a temperature (for example, 60 ° C.) for completing the warm-up of the engine 10 and sufficiently obtaining the heating capacity of the heater core 31 by the cooling water.

  By reducing the valve opening degree of the valve body 151, the reflux amount of the liquid phase working medium in the condensing unit 130 to the evaporation unit 110 is reduced, and the evaporation of the liquid phase working medium in the evaporation unit 110 is suppressed. Therefore, the flow rate of the gas phase working medium flowing into the condensing unit 130 is suppressed, the condensation of the gas phase working medium in the condensing unit 130 is suppressed, and the increase in the cooling water temperature Tw is suppressed. At this time, the temperature decrease degree of the exhaust gas passing through the evaporation unit 110 is reduced, and the heating action of the catalyst 12 by the exhaust gas is increased.

  On the other hand, when the cooling water temperature Tw falls below the predetermined cooling water temperature Tw1, the valve opening degree of the valve body 151 is increased, and the return passage 134 is opened. By increasing the valve opening degree of the valve body 151, the amount of reflux of the liquid phase working medium in the condensing unit 130 to the evaporation unit 110 is increased, and the evaporation of the liquid phase working medium in the evaporation unit 110 is promoted. Accordingly, the flow rate of the gas phase working medium flowing into the condensing unit 130 is increased, the condensation of the gas phase working medium in the condensing unit 130 is promoted, and the rise of the cooling water temperature Tw is promoted. At this time, the temperature decrease degree of the exhaust gas passing through the evaporation unit 110 increases, and the heating action of the catalyst 12 by the exhaust gas decreases.

  If the state where the cooling water temperature Tw exceeds the predetermined cooling water temperature Tw1 continues, the valve body 151 may be fully closed because there is a possibility that the engine 10 may be overheated. In this case, similarly to when the engine 10 is started, the evaporation of the liquid phase working medium in the evaporation unit 110 and the heating of the cooling water due to the condensation of the gas phase working medium in the condensing unit 130 are eliminated, and the exhaust gas is simply evaporated. The catalyst 12 is heated after passing through 110.

  Thus, during the operation of the engine 10, after the cooling water temperature Tw rises to the predetermined cooling water temperature Tw1 or more, the valve opening degree of the valve body 151 is adjusted, and the catalyst temperature Tc and the cooling water temperature Tw are adjusted. Is adjusted.

  In step S130, for example, it is determined whether the engine 10 is stopped based on the fuel injection amount in the operating state signal. The stop of the engine 10 is determined when the fuel injection amount becomes zero. Until the engine 10 is stopped, Steps S120 and S130 are repeated. When it is determined that the engine 10 is stopped, the valve body 151 is fully closed in Step S140.

  When the valve body 151 is fully closed, the liquid phase working medium in the condensing unit 130 is prevented from recirculating to the evaporation unit 110. In the evaporation unit 110, the liquid phase remaining in the evaporation unit 110 due to the residual heat of the exhaust gas. The working medium evaporates and flows into the condensing unit 130. That is, the evaporation unit 110 is in a state in which the liquid phase working medium is eliminated by evaporation, and the condensing unit 130 is in a state in which the liquid phase working medium is stored.

  As described above, in the present embodiment, when the engine 10 is stopped, the return passage 134 is fully closed by the valve mechanism 150, and the engine 10 is started next time so that the catalyst temperature Tc reaches the predetermined catalyst temperature Tc1. The return passage 134 is kept fully closed.

  When the engine 10 is stopped, the return passage 134 is closed, so that the working medium condensed in the condensing unit 130 is not returned to the evaporation unit 110 but is stored in the condensing unit 130. Even after the engine 10 is stopped, the working medium in the evaporation unit 110 is evaporated by the residual heat of the exhaust gas and flows into the condensing unit 130.

  As a result, the next time the engine 10 is started, the liquid phase working medium can be left in the evaporation unit 110, and the working medium cannot be recirculated from the condensing unit 130 to the evaporation unit 110. can do. Until the engine 10 is started and the catalyst temperature Tc reaches a predetermined catalyst temperature Tc1, the internal circulation of the working medium by evaporation and condensation is stopped, that is, the heat exchange between the exhaust gas and the cooling water is stopped, Therefore, it is possible to warm up the catalyst 12 in a short time.

  When the catalyst temperature Tc reaches the predetermined catalyst temperature Tc1, the return passage 134 is opened (fully opened) by the valve mechanism 150.

  By opening the return passage 134, the working medium stored in the condensing unit 130 returns to the evaporating unit 110, and the working medium can be circulated between the evaporating unit 110 and the condensing unit 130. The utilized cooling water can be heated, so that the engine 10 can be warmed up in a short time and the heating performance of the heater core 31 can be improved. Here, since exhaust heat recovery is performed on the upstream side of the catalyst 12, when exhaust gas is recovered on the downstream side, exhaust without temperature decrease should be used as compared with the case where the exhaust temperature is decreased by the catalyst 12. It is possible to recover the exhaust heat by effectively using the heat of the exhaust, and the cooling water can be heated in a short time.

  Further, after the return passage 134 is opened, if the cooling water temperature Tw is higher than the predetermined cooling water temperature Tw1, the valve mechanism 150 changes the side to close the return passage 134, and the cooling water temperature Tw is higher than the predetermined cooling water temperature Tw1. If it is lower, the return passage 134 is changed to the opening side.

  Thereby, when the cooling water temperature Tw is higher than the predetermined cooling water temperature Tw1, the circulation amount of the working medium between the evaporator 110 and the condenser 130 is changed by changing the return passage 134 to the closing side by the valve mechanism 150. Since the temperature can be lowered, the heat recovery of the exhaust can be suppressed, and the increase in the cooling water temperature Tw can be suppressed.

  Further, when the cooling water temperature Tw is lower than the predetermined cooling water temperature Tw1, the circulating amount of the working medium between the evaporation unit 110 and the condensation unit 130 is increased by changing the return passage 134 to the opening side by the valve mechanism 150. Therefore, the heat recovery of the exhaust can be promoted, and the cooling water temperature Tw can be raised. Therefore, the cooling water temperature Tw can be appropriately maintained.

  The valve mechanism 150 is an electric drive valve 150 that is configured to close the return passage 134 when energization is stopped by the control unit 160 and to open the return passage 134 when energized by the control unit 160. Configured to open.

  Thus, when the engine 10 is stopped, the control unit 160 may stop energization of the valve mechanism 150 in order to close the return passage 134. Therefore, during the stop of the engine 10 and until the next time the engine 10 is started and the catalyst 12 reaches the predetermined catalyst temperature Tc1, it is possible to respond without using electric power to close the return passage 134.

(Second Embodiment)
In the first embodiment, the return passage 134 is closed by the valve mechanism 150 when the engine 10 stops. However, the present invention is not limited to this, and the return passage 134 may be closed immediately before the engine 10 stops. The time immediately before the engine 10 is stopped is, for example, about 5 to 10 seconds before the engine 10 is stopped.

  The timing immediately before the stop of the engine 10 is, for example, when the vehicle speed signal from the vehicle speed sensor (FIG. 4 (a)) is output to the control unit 160, and the control unit 160 is configured to continuously decrease the vehicle speed. This can be handled by calculating the timing just before the vehicle speed becomes zero and determining the timing immediately before.

  In this way, by slightly advancing the timing of closing the return passage 134, it is possible to earn time for evaporating the liquid phase working medium remaining in the evaporation unit 110, and the evaporation unit 110 is reliably ensured at the next start of the engine 10. It can be in a state without a liquid phase working medium.

(Third embodiment)
In the first embodiment, the return passage 134 is closed by the valve mechanism 150 when the engine 10 is stopped. However, the present invention is not limited to this, and the return passage 134 may be closed immediately after the engine 10 is stopped. Immediately after the engine 10 is stopped, for example, the timing is about 1 to 5 seconds after the engine 10 is stopped.

  The timing immediately after the stop of the engine 10 is measured, for example, from the time when the fuel injection amount of the first embodiment becomes zero, and the time point after a predetermined time can be determined as the “immediately” timing. .

  Thus, even when the timing for closing the return passage 134 is somewhat delayed from the timing at which the engine 10 is stopped, substantially the same effect as in the first embodiment can be obtained.

(Fourth embodiment)
In the first and second embodiments, the valve mechanism 150 uses an electric drive valve to fully close the return passage 134 so that the passage area of the return passage 134 is zero. In addition to the fully open state, it is possible to form an intermediate state with an arbitrary passage area between the fully closed state and the fully open state. And a fully open state electromagnetic valve. The solenoid valve is preferably a normally closed valve that forms a fully closed state when energization from the control unit 160 is stopped and forms a fully open state when energized.

  In this case, the control in step S120 in the control flow described in the first embodiment is performed by switching between the fully closed state and the fully open state. Thereby, the valve mechanism 150 can be made inexpensive.

(Other embodiments)
In the first embodiment, the fuel injection amount is used to determine the stop timing of the engine 10, and in the second embodiment, the vehicle speed is used to determine the timing immediately before the engine 10 is stopped. Then, the fuel injection amount is used to determine the timing immediately after the stop of the engine 10, but in addition to these, the intake air amount of the engine 10, the engine speed, and the like may be used.

  Further, in each of the above embodiments, the condensing unit 130 is disposed on the side of the evaporation unit 110 as a basic structure of the exhaust heat recovery apparatus 100. 130 may be provided. In this case, the tubes 131 of the condensing unit 130 are preferably arranged horizontally.

10 Engine (Internal combustion engine)
DESCRIPTION OF SYMBOLS 11 Exhaust pipe 12 Catalyst 100 Exhaust heat recovery apparatus 110 Evaporating part 130 Condensing part 134 Return path 150 Valve mechanism 160 Control part

Claims (5)

In the middle of the exhaust pipe (11) of the internal combustion engine (10), a catalyst (12) for purifying the exhaust gas of the internal combustion engine (10) is disposed, and from the catalyst (12) of the exhaust pipe (11). Is an exhaust heat recovery device provided upstream of the exhaust flow,
An evaporation section (110) for evaporating an internal working medium by heat of the exhaust;
A condensing unit (130) for radiating heat of the working medium flowing from the evaporation unit (110) to the cooling water of the internal combustion engine (10) to condense the working medium;
A return passage (134) for returning the condensed working medium to the evaporator (110);
A valve mechanism (150) provided in the return passage (134) for adjusting a passage area of the return passage (134);
When the internal combustion engine (10) is stopped, immediately before the stop, or immediately after the stop, the valve mechanism (150) closes the return passage (134), and the internal combustion engine (10) is next time. And a control unit (160) for maintaining the closed state of the return passage (134) until the temperature (Tc) of the catalyst (12) reaches a predetermined catalyst temperature (Tc1) that is started and reaches a predetermined catalyst temperature (Tc1). An exhaust heat recovery device. The valve mechanism (150) is an electric drive valve (150),
The return path (134) is closed when energization is stopped by the control unit (160), and the return path (134) is opened when energized by the control unit (160). The exhaust heat recovery apparatus according to claim 1, wherein   The controller (160) opens the return passage (134) by the valve mechanism (150) when the temperature (Tc) of the catalyst (12) reaches the predetermined catalyst temperature (Tc1). The exhaust heat recovery device according to claim 1 or 2.   When the cooling water temperature (Tw) is higher than a predetermined cooling water temperature (Tw1) after opening the return passage (134), the control unit (160) opens the valve mechanism (150). The return passage (134) is changed to the closing side, and when the cooling water temperature (Tw) is lower than the predetermined cooling water temperature (Tw1), the return passage (134) is changed to the opening side. The exhaust heat recovery apparatus according to claim 3.   The said evaporation part (110), the said condensation part (130), and the said return channel | path (134) form the loop type heat pipe, The any one of Claims 1-4 characterized by the above-mentioned. The exhaust heat recovery device according to claim 1.

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