JP2007046469A - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device eliminating pressure difference between an evaporation part and a condensation part and surely restarting at a time of restart after exhaust heat recovery stop. <P>SOLUTION: In the exhaust heat recovery device provided with the evaporation part 110A in an exhaust pipe 11 for exhaust gas circulation of an internal combustion engine 10, and with the condensation part 110B in an cooling water flow passage 30 for cooling water circulation of the internal combustion engine 10, and including a heat pipe 110 provided with thermal switch function regulating heat transmission quantity to the condensation part 110B according to increase of heating quantity to the evaporation part 110A and temperature of cooling water flowing into the condensation part 110B, and transmitting exhaust heat of exhaust gas to cooling water by the heat pipe 110, a valve 31 stopping flow of cooling water to the condensation part 110B by closing the cooling water flow passage 30 and a control means 102 controlling open and close of the valve 31 are provided, and a control means 102 closes the valve 31 when exhaust heat of exhaust gas is need to be transmitted to cooling water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery apparatus suitable for recovering exhaust heat of exhaust gas from, for example, a vehicle internal combustion engine and applying it to cooling water heating of the internal combustion engine.

  2. Description of the Related Art Conventionally, as shown in Patent Document 1, for example, a heat siphon type exhaust heat recovery device for recovering heat of engine exhaust gas to engine cooling water is known.

Here, the evaporator of the heat siphon type exhaust heat recovery device is arranged in the exhaust pipe of the engine, the condenser is arranged on the cooling water side, and the condensate outlet side passage of the condenser is arranged by the control device according to the engine water temperature. An on-off valve that is opened and closed is arranged. When the water temperature is higher than the predetermined temperature, the control device closes the on-off valve to stop the reflux of the internal heat medium to stop the exhaust heat recovery, and when the water temperature becomes lower than the predetermined temperature, the on-off valve Is opened, the internal heat medium is refluxed, and the exhaust heat recovery is restarted.
JP-A-7-120178

  However, once the rise in water temperature is sensed and the on-off valve is closed to stop the circulation of the heat medium, the heat medium continues to evaporate in the evaporator, so almost all of the heat medium is in the state of condensed water in the condenser. The evaporation section side is filled with high-pressure superheated steam.

  That is, the evaporator is kept at a high pressure and the condenser is kept at a low pressure. Even if the water temperature drop is detected from such a state and the on-off valve is opened again, the pressure difference between the evaporation unit and the condensing unit overcomes gravity and the condensed water cannot be recirculated and the exhaust heat recovery does not restart.

  In view of the above problems, an object of the present invention is to provide an exhaust heat recovery device that eliminates the pressure difference between the evaporation section and the condensation section and can be restarted reliably when restarting after stopping exhaust heat recovery. is there.

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

  In the first aspect of the present invention, the evaporation section (110A) is disposed in the exhaust pipe (11) for exhaust gas flow of the internal combustion engine (10), and the condensing section (110B) is a cooling water flow of the internal combustion engine (10). Condensed in accordance with the temperature of the cooling water of the internal combustion engine (10) flowing into the condensing unit (110B) while increasing the heating amount to the evaporating unit (110A) or being disposed in the common cooling water flow path (30) In the exhaust heat recovery apparatus, which has a heat pipe (110) having a heat switch function that regulates the amount of heat transported to the section (110B), and transports exhaust heat of exhaust gas to cooling water by the heat pipe (110) A valve (31) for stopping the flow of the cooling water to the condensing part (110B) by closing the cooling water flow path (30), and a control means (102) for controlling opening and closing of the valve (31), The control means (102) When it is desired to transport the waste heat of the gas-gas to the cooling water, it is characterized by closing the valve (31).

  Thereby, since the cooling water does not flow to the condensing part (110B), the heat transfer from the condensing part (110B) to the cooling water is reduced, and the temperature of the condensing working medium staying in the condensing part (110B) is increased. The internal pressure in the condensing unit (110B) can be increased. Therefore, the pressure difference between the evaporation section (110A) and the condensation section (110B) can be reduced, and the condensed working medium staying in the condensation section (110B) can be returned to the evaporation section (110A). 110), the exhaust heat recovery from the exhaust gas to the cooling water can be reliably restarted.

  In invention of Claim 2, a control apparatus (102) determines that the control state of the amount of heat transport by a heat switch function is judged by the inlet-outlet temperature difference (Tw2-Tw1) of the cooling water in a condensation part (110B). It is a feature.

  As a result, the amount of heat transported to the cooling water correlates with the cooling water inlet / outlet temperature difference (Tw2−Tw1). By using this inlet / outlet temperature difference (Tw2−Tw1), heat can be easily and reliably obtained. It is possible to grasp the regulated state of the transportation amount.

  In the invention according to claim 3, the valve (31) is provided with a minute hole (31b), and when the valve (31) is closed, the cooling water flows into the cooling water flow path (31b) through the minute hole (31b). 30) is distributed in a minute amount.

  Thereby, since the flow of the cooling water in the cooling water flow path (30) can be ensured even when the valve (31) is closed, the inlet / outlet temperature difference (Tw2-Tw1) in the invention according to claim 2 can be accurately grasped. be able to. In addition, since the cooling water which distribute | circulates by the micro hole (31b) is made into a trace amount, the effect of the internal pressure rise of the condensation part (110B) in the invention of Claim 1 is not prevented fundamentally.

  In contrast to the invention according to claim 2, as in the invention according to claim 4, the control device (102) determines the state of regulation of the amount of heat transport by the heat switch function of the exhaust gas in the evaporation section (110A). The determination may be made based on the difference in the inlet / outlet gas temperature or the surface temperature difference between the evaporator (110A) and the condenser (110B) in the heat pipe (110).

  Thereby, the regulated state of the amount of heat transport can be determined easily and reliably.

  The invention according to claim 5 is characterized in that the control means (102) closes the valve (31) when the exhaust heat quantity of the exhaust gas is smaller than a predetermined heat quantity.

  Thereby, when the exhaust heat amount of the exhaust gas is high, the internal pressure of the heat pipe (110) suddenly increases when the valve (31) is closed, and the heat pipe (110) may be damaged. Here, such a problem can be avoided.

  In the invention according to claim 5, as in the invention according to claim 6, the control means (102) sets the exhaust heat amount of exhaust gas to the exhaust gas temperature (Tg 1) or the rotation of the internal combustion engine (10). It can be grasped from the number.

  Further, in contrast to the invention described in claim 5, as in the invention described in claim 7, the control means (102) is configured such that when the pressure in the heat pipe (110) is lower than a predetermined pressure, the valve (31 ) May be closed, and the heat pipe (110) can be similarly prevented from being damaged.

  In the invention according to claim 8, the evaporation section (110A) is disposed in the exhaust pipe (11) for circulating the exhaust gas of the internal combustion engine (10) for the hybrid vehicle, and the condensing section (110B) is the internal combustion engine (10). ) In the cooling water flow path (30) for circulating the cooling water, the heating amount to the evaporation section (110A) is increased, or the cooling water temperature of the internal combustion engine (10) flowing into the condensation section (110B) Accordingly, it has a heat pipe (110) having a heat switch function in which the amount of heat transport to the condensing unit (110B) is regulated, and the heat pipe (110) is used to transport the exhaust heat of the exhaust gas to the cooling water. In the heat recovery device, when the amount of heat transport is regulated by the heat switch function, control means (102A) for stopping the internal combustion engine (10) is provided when it is desired to transport the exhaust gas exhaust heat to the cooling water again. Specially It is set to.

  As a result, the exhaust gas does not enter the evaporation section (110A) when the internal combustion engine (10) is stopped, so that the temperature of the evaporation section (110A) of the heat pipe (110) can be rapidly reduced. Therefore, the pressure difference between the evaporation section (110A) and the condensation section (110B) can be eliminated, and the condensed working medium staying in the condensation section (110B) is returned to the evaporation section (110A), and the heat pipe ( 110), the exhaust heat recovery from the exhaust gas to the cooling water can be reliably restarted.

  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.

(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 formed of an exhaust heat recovery device 101, a control device 102, a valve 31, various sensors 13, 25, 32, 33, and the like disposed in the exhaust pipe 11 and the cooling water flow path 30 of the engine 10. Yes. A specific configuration will be described below with reference to FIGS.

  1 is a schematic diagram showing a state in which the exhaust heat recovery apparatus 100 is mounted on a vehicle, FIG. 2 is a sectional view showing a valve 31, FIG. 3 is a side view showing an exhaust heat recovery device 101, and FIG. It is sectional drawing which shows AA part.

  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. The exhaust pipe 11 is provided with a catalytic converter 12 for purifying exhaust gas.

  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 cooling water flow path 30 through which cooling water circulates as a flow path different from the radiator circuit 20; And a heater circuit 40 that heats the conditioned air using cooling water (hot water) as a heating source.

  The radiator circuit 20 is provided with a radiator 21, and the radiator 21 cools the cooling water circulated by the water pump 22 by heat exchange with the outside air. The radiator circuit 20 is provided with a bypass flow path 23 that bypasses the radiator 21 and flows the cooling water, and the thermostat 24 adjusts the amount of cooling water that flows through the radiator 21 and the amount of cooling water that flows through the bypass flow path 23. It has come to be. In particular, during warm-up, the amount of cooling water on the bypass flow path 23 side is increased, and warm-up is promoted. That is, overcooling of the cooling water by the radiator 21 is prevented. A water temperature sensor 25 is provided in the bypass channel 23. The water temperature sensor 25 is a sensor that detects the temperature of the cooling water flowing out from the engine 10 (hereinafter, engine outlet water temperature Tw), and the detected temperature signal is input to the control device 102 described later. Yes.

  The cooling water passage 30 is a passage branched from the engine outlet of the radiator circuit 20 and connected to the water pump 22, and the cooling water is circulated by the water pump 22. A water tank 140 (condensing unit 110B) of the exhaust heat recovery unit 101, which will be described later, is connected in the middle of the cooling water flow path 30. A valve 31 that opens and closes the cooling water passage 30 is provided on the upstream side of the water tank 140.

  The valve 31 is a rotary type here, and as shown in FIG. 2, the valve 31 is formed with a circulation part 31a as a flow path for cooling water circulation, and is further substantially orthogonal to the circulation part 31a. A minute hole 31b is formed. The rotation of the valve 31 (opening / closing of the flow path) is controlled by a control device 102 described later. When the valve 31 is rotated to the position of FIG. The circulation part 31a communicates, a valve opening state is formed, and cooling water circulates. When the valve 31 is rotated to the position shown in FIG. 2B, the cooling water flow path 30 is closed by the valve 31 to form a valve closing state, and basically the flow of the cooling water is stopped. . However, since the cooling water channel 30 and the minute hole 31b communicate with each other, a very small amount of cooling water (for example, about 2 L / min) is allowed.

  Returning to FIG. 1, in the cooling water flow path 30, a water temperature sensor 32 is provided on the upstream side close to the water tank 140, and a water temperature sensor 33 is provided on the downstream side close to the water tank 140. The water temperature sensor 32 is a sensor for detecting the temperature of the cooling water flowing into the water tank 140 (hereinafter referred to as the inlet water temperature Tw1), and the detected temperature signal is input to the control device 102 described later. . Similarly, the water temperature sensor 33 is a sensor that detects the temperature of the cooling water flowing out from the water tank 140 (hereinafter, outlet water temperature Tw2), and the detected temperature signal is input to the control device 102 described later. It has become.

  The heater circuit 40 is a circuit in which cooling water (hot water) flows out from a portion different from the engine outlet of the radiator circuit 20 and merges downstream of the cooling water passage 30. The heater circuit 40 is provided with a heater core 41 as a heat exchanger for heating, and cooling water (hot water) is circulated by the water pump 22. The heater core 41 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.

  As shown in FIGS. 3 and 4, the exhaust heat recovery device 101 includes fins 120 provided outside a plurality (here, three) of heat pipes 110, and one end side (evaporating unit 110 </ b> A) of the heat pipe 110 is provided. The other end side (condensing part 110 </ b> B) is disposed in the water tank 140 and is formed in the exhaust pipe part 130. Each member (hereinafter described) constituting the exhaust heat recovery device 101 is made of a stainless material having high corrosion resistance, and after the members are assembled, the brazing material provided in the abutting portion and the fitting portion is integrally formed. It is brazed.

  The heat pipe 110 is formed by providing an orifice 112 in a container 111 and enclosing a working medium in the container 111. The container 111 is composed of a straight circular tube, and is used in a posture in which the longitudinal direction is directed in the vertical direction. The orifice 112 is a constricted portion that reduces the cross-sectional area of the flow path in the container 111, and a meat portion projects from the inner wall surface 111a in the container 111 toward the center to form a circular hole 112a in the center. ing.

  Each heat pipe 110 is provided with an enclosing portion (not shown), and the inside of the heat pipe 110 is evacuated (depressurized) from the enclosing portion, and the enclosing portion is sealed after the working medium is encapsulated. Here, water is used as the working medium. The boiling point of water is usually 100 ° C. (at 1 atm), but since the inside of the tube 110 is depressurized (eg, 0.01 atm), the boiling point is 5 to 10 ° C. As the working medium, alcohol, fluorocarbon, chlorofluorocarbon or the like may be used in addition to water.

  The heat pipe 110 having the above configuration functions as a bottom heat type by forming an evaporation unit 110A on the lower side, a condensation unit 110B on the upper side, and a heat insulating unit 110C between the two 110A and 110B.

  A plurality of heat pipes 110 are arranged, and plate-type fins 120 formed of a thin plate material are joined to the outer wall surfaces of the portions corresponding to the evaporation section 110A and the condensation section 110B of each heat pipe 110. Further, the evaporation section 110A of each heat pipe 110 is disposed in an exhaust pipe section 130 that forms a duct having a rectangular cross section, and the condensing section 110B is disposed in a water tank 140 that forms a rectangular parallelepiped container. An inlet pipe 141 and an outlet pipe 142 communicating with the water tank 140 are joined to the water tank 140 so as to face each other.

  As described above, the exhaust heat recovery device 101 is formed, the exhaust pipe portion 130 is interposed in the exhaust pipe 11 on the downstream side of the catalytic converter 12, and both the pipes 141 and 142 of the water tank 140 are the cooling water flow paths. 30 (FIG. 1).

  As shown in FIG. 1, the control device 102 as a control means is composed of a microcomputer and its peripheral circuits, and responds to various temperature signals from the exhaust temperature sensor 13, the water temperature sensors 25, 32, and 33 in accordance with a preset program. While performing arithmetic processing, opening / closing control of the valve 31 is performed.

  Next, the operation of the exhaust heat recovery apparatus 100 based on the above configuration will be described.

  When the engine 10 is operated, the water pump 22 is operated, and the cooling water circulates through the radiator circuit 20, the cooling water flow path 30, and the heater circuit 40. The control device 102 normally controls the valve 31 to be in an open state. The exhaust gas of the fuel combusted by the engine 10 flows through the exhaust pipe 11 through the catalytic converter 12, passes through the exhaust pipe part 130 of the exhaust heat recovery device 101 (outside the evaporation part 110A), and is discharged into the atmosphere. The Further, the cooling water circulating through the cooling water flow path 30 passes through the water tank 140 of the exhaust heat recovery device 101 (outside the condensing unit 110B).

  In the exhaust heat recovery device 101, when the engine 10 is in a low load to medium load state (exhaust gas exhaust heat amount is low to medium state), first, water (working medium) in the heat pipe 110 is evaporated by the evaporation unit 110A. Then, it receives heat from the exhaust gas flowing through the exhaust pipe 11 and starts to evaporate to boil, rises into the heat pipe 110 as steam, and flows into the condensing unit 110B through the orifice 112. The steam that has flowed into the condensing unit 110B is cooled by the cooling water flowing through the cooling water channel 30, becomes condensed water on the inner wall surface 111a, descends due to gravity, and returns to the evaporation unit 110A through the orifice 112.

  Further, when the evaporation in the evaporation unit 110A progresses, the upward steam flow rate from the evaporation unit 110A increases, and the condensed water that descends from the condensation unit 110B and returns to the evaporation unit 110A jumps up due to this vapor flow rate. Accordingly, the reflux amount of the condensed water becomes constant (scattering limit), and the amount of heat that can be transported is determined as the limit heat transport amount (maximum heat transport amount).

  In this way, the heat of the exhaust gas is transferred to the water and transported from the evaporation unit 110A to the condensing unit 110B. When the vapor condenses in the condensing unit 110B, the cooling water is released as condensation latent heat and flows through the cooling water channel 30. Is heated. The heat of the exhaust gas is also transferred to the condensing unit 110B from the evaporation unit 110A by heat conduction through the outer wall surface of the heat pipe 110.

  As the exhaust gas temperature increases with the load on the engine 10, the amount of heat transported from the evaporator 110A to the condenser 110B, that is, the cooling water, up to a predetermined load (predetermined exhaust heat amount of the exhaust gas) of the engine 10 The amount of heat transfer increases gradually (execution of exhaust heat recovery by the heat pipe 110).

  Thus, when the engine 10 is started when the outside air temperature is relatively low, exhaust heat recovery by the heat pipe 110 is executed, the cooling water is positively heated, and warming up of the engine 10 is promoted. Therefore, reduction of the friction loss of the engine 10 and suppression of fuel increase for improving low temperature startability are achieved, and fuel efficiency is improved. Moreover, the heating performance of the heater core 41 using cooling water as a heat source is improved.

  On the other hand, when the engine 10 shifts to a high load state (exhaust gas exhaust heat amount is high), the load of the engine 10 increases from a predetermined load, and the exhaust gas temperature further rises, Boiling occurs, and a boiling film is formed on the inner wall surface 111a of the evaporation section 110A. Then, the thermal resistance of the evaporation unit 110A is increased, and the heat from the exhaust gas is hardly transmitted to the evaporation unit 110A, and the limit heat transport amount is rapidly reduced as the exhaust gas temperature rises.

  Furthermore, the water in the evaporation unit 110A is completely evaporated, and the upward steam flow velocity prevents the condensed water condensed in the condensing unit 110B from descending, so that the condensed water flows on the inner wall surface 111a of the condensing unit 110B. Retained (dry out). Then, heat transport due to evaporation and condensation of water is stopped, and the amount of heat transmitted to the cooling water side is only heat conduction through the heat pipe 110 (the exhaust heat recovery by the heat pipe 110 is stopped, and in the present invention). Corresponding to the regulation of heat transport amount by the thermal switch function).

  Therefore, if the exhaust gas temperature becomes higher as the load of the engine 10 increases, if the exhaust heat recovery is continued as it is, the cooling water temperature rises too much, exceeding the heat dissipation capability of the radiator 20 and leading to overheating. The problem is prevented by switching to the exhaust heat recovery stop.

  Here, as described in the above section “Problem to be Solved by the Invention”, when the exhaust heat recovery is stopped, most of the water in the evaporation section 110A evaporates to become high-pressure superheated steam, and the condensation section 110B. Condensed water stays in the area. Since a pressure difference is generated between the evaporation unit 110A and the condensation unit 110B in this manner (evaporation unit 110A internal pressure> condensation unit 110B internal pressure), once the exhaust heat recovery is stopped, the engine 10 returns to a low load state. If the exhaust heat recovery is executed again, the above pressure difference is not easily eliminated, and the pressure difference between the evaporation unit 110A and the condensation unit 110B overcomes the gravity, and the condensed water returns to the evaporation unit 110A from the condensation unit 110B. Inability to recover the exhaust heat is not possible.

  Therefore, in the present embodiment, the control device 102 performs opening / closing control of the valve 31 based on the control flowchart shown in FIG. 5 in order to reliably restart the exhaust heat recovery.

  That is, first, the predetermined threshold values To1, To2, and Tgo are read together with the start of the engine 10 in step S100. Here, the threshold value To1 is used to determine whether or not to perform exhaust heat recovery, and is a water temperature threshold value (for example, 80 ° C.) set for the engine outlet water temperature Tw. Further, the threshold value To2 is used to determine the exhaust heat recovery stop state, and a water temperature difference threshold value (for example, a cooling water inlet / outlet temperature difference Tw2−Tw1) between the outlet water temperature Tw2 and the inlet water temperature Tw1 (for example, 2 ° C). Further, the threshold value Tgo is used to determine whether or not the valve 31 can be switched to the closed state, and the exhaust gas temperature threshold value set for the exhaust gas temperature Tg1 so as to capture the exhaust heat amount of the exhaust gas from the temperature. (For example, 400 ° C.).

  Subsequently, the valve 31 is opened in step S110, the engine outlet water temperature Tw from the water temperature sensor 25, the inlet water temperature Tw1 from the water temperature sensor 32, the outlet water temperature Tw2 from the water temperature sensor 33, and the exhaust temperature sensor 13 in step S120. Each exhaust gas temperature Tg1 is read.

  In step S130, the engine outlet water temperature Tw is compared with the water temperature threshold value To1, and if the engine outlet water temperature Tw is lower than the water temperature threshold value To1 (in the case of an affirmative determination), the process proceeds to step S140, and the engine outlet water temperature Tw is the water temperature threshold value. When higher than To1 (in the case of negative determination), the process proceeds to step S180. Here, if the determination is affirmative, the engine outlet water temperature Tw is low and the exhaust heat recovery should be performed. Conversely, if the determination is negative, the engine outlet water temperature Tw is sufficiently high and exhaust heat recovery should be stopped. It means that there is.

  In step 140, the cooling water inlet / outlet temperature difference Tw2-Tw1 in the water tank 140 (condensing unit 110B) is compared with the water temperature difference threshold value To2, and the inlet / outlet temperature difference Tw2-Tw1 is lower than the water temperature threshold value To2 (Yes). In the case of determination), the process proceeds to step S150, and in the case where the inlet / outlet temperature difference Tw2-Tw1 is higher than the water temperature threshold To2 (in the case of negative determination), the process proceeds to step S180. Here, in the case of an affirmative determination, there is no heat dissipation from the condenser 110B to the cooling water, and the exhaust heat recovery is in a stopped state. On the contrary, in the case of a negative determination, there is heat dissipation to the cooling water and the exhaust heat recovery is executed. Means that

  In step S150, the exhaust gas temperature Tg1 is compared with the exhaust gas temperature threshold Tgo. If the exhaust gas temperature Tg1 is lower than the exhaust gas temperature threshold Tgo (in the case of an affirmative determination), the process proceeds to step S160. When the temperature Tg1 is higher than the exhaust gas temperature threshold Tgo (in the case of negative determination), the process proceeds to step S180. Here, in the case of an affirmative determination, the amount of heat of the exhaust gas is sufficiently small, and even if the valve 31 is closed, the pressure in the heat pipe 110 does not increase rapidly and there is no fear of damage to the heat pipe 110. In the case of determination, it means a case where the valve 31 is closed (by stopping the flow of the cooling water), and the pressure in the heat pipe 110 suddenly increases and the heat pipe 110 may be damaged.

  In step S160, it is determined whether or not the current valve 31 is in an open state. If the valve 31 is in the open state, the valve 31 is closed in step S170, and if the valve 31 is in the closed state, the closed state is maintained. Then, the process returns to step S120.

  On the other hand, in step 180 after determining NO in steps S130 to S150, it is determined whether or not the current valve 31 is in an open state. If the valve 31 is in an open state, the open state is maintained as it is. If the valve is closed, the valve 31 is opened in step S190, and the process returns to step S120.

  In the above control, when both the determination in step S130 to step S160 is affirmative and the valve 31 is closed in step S170, after the exhaust heat recovery is stopped, the condition returns to the condition for performing the exhaust heat recovery, and This is a case where the exhaust heat quantity of the exhaust gas is small. When the valve 31 is closed here, the heat transfer from the condensing part 110B to the cooling water in the cooling water flow path 30 is lowered, the heat exchange performance is lowered, and the condensed water stays in the condensing part 110B. The pressure in the portion 110B can be increased. Therefore, the pressure difference between the evaporation unit 110A and the condensation unit 110B can be reduced, and the condensed water staying in the condensation unit 110B can be returned to the evaporation unit 110A to reliably restart the exhaust heat recovery. It becomes.

  When the exhaust heat recovery is restarted by the control in step S170 (valve 31 is closed), the inlet / outlet temperature difference Tw2-Tw1 becomes higher than the water temperature difference threshold To2, so the determination in step S140 is negative, and step S190 By opening the valve 31, the normal state can be restored.

  In the present embodiment, whether or not exhaust heat recovery is being performed is determined by using the cooling water inlet / outlet temperature difference Tw2−Tw1 that correlates with the amount of heat transport to the cooling water. And the execution state of exhaust heat recovery can be grasped | ascertained reliably.

  Further, since the minute hole 31b is provided in the valve 31, the flow of the cooling water in the cooling water flow path 30 can be secured even when the valve 31 is closed, and the inlet / outlet temperature difference Tw2-Tw1 can be accurately grasped. it can. In addition, since the cooling water flowing through the minute holes 31b is very small, the effect of the internal pressure increase of the condensing unit 110B when the valve 31 is closed is not obstructed.

  Further, since the exhaust gas exhaust heat amount (exhaust gas temperature) in step S150 is viewed as a condition for closing the valve 31, when the exhaust gas exhaust heat amount is high, the heat pipe is used when the valve 31 is closed. Although it is conceivable that the internal pressure of 110 may rapidly increase and the heat pipe 110 may be damaged, such a problem can be avoided here.

  In the first embodiment, the safety confirmation when the valve 31 is closed is determined based on the exhaust gas temperature Tg1 correlated with the exhaust heat exhaust amount (step S150). It is also possible to determine. In this case, what is necessary is just to determine with safety, when rotation speed is lower than predetermined rotation speed.

  Alternatively, this safety confirmation determination may be used by directly measuring the internal pressure of the heat pipe 110 or the temperature of the working medium (water) instead of the exhaust gas exhaust heat amount (exhaust gas temperature Tg1). When the internal pressure is used, it is determined to be safe when the pressure is lower than the predetermined pressure, and when the temperature is used, it is determined to be safe when the temperature is lower than the predetermined temperature.

(Second Embodiment)
A second embodiment of the present invention is shown in FIGS. In the second embodiment, the exhaust heat recovery device 100 is mounted on a hybrid vehicle as compared with the first embodiment, and the valve 31 and the exhaust temperature sensor 13 are eliminated as shown in FIG. The control device 102A controls the operation of the engine 10.

  In the second embodiment, the control device 102A performs control based on the control flowchart shown in FIG. That is, in step S101, when the engine 10 is started, the threshold values To1, To2, and Tmo are read, and the timer is reset. Here, the threshold value Tmo is a predetermined time (for example, 5 seconds) when exhaust heat recovery is restarted.

  Subsequently, in step S121, the engine outlet water temperature Tw is read from the water temperature sensor 25, the inlet water temperature Tw1 is read from the water temperature sensor 32, and the outlet water temperature Tw2 is read from the water temperature sensor 33.

  Then, in step S125, it is determined whether or not the engine 10 is in an operating state. If it is determined that the engine 10 is in an operating state, the process proceeds to step S130.

  In step S130, as in the first embodiment, the engine outlet water temperature Tw is compared with the water temperature threshold value To1, and if the engine outlet water temperature Tw is lower than the water temperature threshold value To1 (in the case of an affirmative determination), the process proceeds to step S140. When the engine outlet water temperature Tw is higher than the water temperature threshold To1 (in the case of negative determination), the process returns to step S121.

  In step 140, the cooling water inlet / outlet temperature difference Tw2-Tw1 is compared with the water temperature threshold value To2, and if the inlet / outlet temperature difference Tw2-Tw1 is lower than the water temperature threshold value To2 (in the case of an affirmative determination), the process proceeds to step S200. In step S200, the engine 10 is stopped, and in step S210, timer counting is started. In step S140, when the inlet / outlet temperature difference Tw2-Tw1 is higher than the water temperature threshold To2 (in the case of negative determination), the process returns to step S121.

  On the other hand, in step S220 after determining NO in step S125, it is determined whether or not the timer is counting. If YES in step S230, it is determined whether or not the predetermined time Tmo has elapsed in step S230. If Tmo has elapsed, the engine 10 is operated in step S240, and the timer is reset in step S250. If NO is determined in both step S220 and step S230, the process returns to step S121.

  The feature of the control in the second embodiment is that the engine 10 cannot be stopped while driving in a general engine vehicle, but the hybrid vehicle can be driven by a driving motor and the engine can be stopped during driving. Therefore, this characteristic is used for restarting exhaust heat recovery.

  That is, in the control of the second embodiment, instead of closing the valve 31 as in the first embodiment, the exhaust gas enters the exhaust pipe section 130 (evaporating section 110A) by stopping the engine 10 in step S200. Therefore, the temperature of the evaporator 110A of the heat pipe 110 can be rapidly reduced.

  Therefore, the pressure difference between the evaporation unit 110A and the condensation unit 110B can be eliminated, the condensed water staying in the condensation unit 110B is returned to the evaporation unit 110A, and the exhaust heat recovery by the heat pipe 110 is reliably restarted. Can be made.

  Then, after exhaust heat recovery is restarted by the control of step S200 (stop of the engine 10), a determination of NO is made in step S125 (engine stop determination), and the determination in steps S220 and S230 is a predetermined time Tom. After elapses, the engine 10 is started again and can be returned to the normal state.

  In addition, in the restart control of exhaust heat recovery in the second embodiment, unlike the case of a general engine vehicle, the heat pressure from the exhaust gas is lost when the engine 10 is stopped, so that the internal pressure of the heat pipe 110 is reduced. Since there is no concern that the temperature will rise abnormally, safety determination based on the exhaust gas temperature Tg1 (determination in step S150 in the first embodiment) is unnecessary.

  The hybrid vehicle is not limited to the second embodiment, but may be controlled in accordance with the first embodiment.

(Other embodiments)
In each of the embodiments described above, whether exhaust heat recovery is performed or stopped is determined using the inlet / outlet temperature difference Tw2−Tw1 (step S140), but is not limited thereto, and the exhaust gas in the exhaust pipe unit 130 (evaporating unit 110A) is not limited thereto. The determination may be made using the inlet / outlet temperature difference. Alternatively, the determination can also be made based on the surface temperature difference between the evaporation unit 110A and the condensation unit 110B in the heat pipe 110.

  In these cases, since it is not necessary to use the water temperature sensors 32 and 33, it is not necessary to set the minute hole 31b in the valve 31, and the cooling water may be completely shut off.

  Further, since the measured value of the water temperature sensor 32 (inlet water temperature Tw1) is almost the same as the measured value of the water temperature sensor 25 (engine outlet water temperature Tw), the engine outlet water temperature Tw may be substituted for the inlet water temperature Tw1, This is advantageous in terms of cost.

  Further, in order to provide the heat pipe 110 with the heat switch function that enables switching between execution and stop of the exhaust heat recovery, the heat pipe 110 is provided with the orifice 112. An opening / closing valve is provided between 110A and the condensing unit 110B, an inner wall surface 111a of the condensing unit 110B is provided with a condensed water holding function, or the amount of working medium enclosed in the heat pipe 110 is set to a predetermined amount in advance. It may be regulated.

  Moreover, although the shape of the heat pipe 110 (container 111) is a circular tube, the shape is not limited to this, and may be a square tube, a flat tube, a multi-hole tube, or the like. Furthermore, it is good also as a loop type heat pipe.

  As shown in Patent Document 1, the heat switch function in this loop heat pipe is achieved by controlling the open / close valve of the condensed water recirculation path that recirculates condensed water from the condensing unit to the heating unit in accordance with the cooling water temperature of the internal combustion engine. Achieved.

It is a schematic diagram which shows the mounting state to the vehicle of the waste heat recovery apparatus in 1st Embodiment. It is sectional drawing which shows a valve | bulb. It is a side view which shows an exhaust heat recovery device. It is sectional drawing which shows the AA part of FIG. It is a control flowchart used for valve | bulb opening / closing control which the control apparatus in 1st Embodiment performs. It is a schematic diagram which shows the mounting state to the vehicle of the waste heat recovery apparatus in 2nd Embodiment. It is a control flowchart used for the engine stop start control which the control apparatus in 2nd Embodiment performs.

Explanation of symbols

10 Engine (Internal combustion engine)
DESCRIPTION OF SYMBOLS 11 Exhaust pipe 30 Cooling water flow path 31 Valve 31b Micro hole 100 Waste heat recovery apparatus 101 Waste heat recovery apparatus 110 Heat pipe 110A Evaporating part 110B Condensing part 102, 102A Control apparatus (control means)

Claims (8)

The evaporation section (110A) is disposed in the exhaust pipe (11) for circulating the exhaust gas of the internal combustion engine (10), and the condensing section (110B) is the cooling water flow path (30) for circulating the cooling water of the internal combustion engine (10). To the condensing unit (110B) according to the increase in the heating amount to the evaporation unit (110A) or the temperature of the cooling water of the internal combustion engine (10) flowing into the condensing unit (110B). A heat pipe (110) having a heat switch function that regulates the amount of heat transport of
In the exhaust heat recovery apparatus for transporting exhaust heat of the exhaust gas to the cooling water by the heat pipe (110),
A valve (31) for stopping the flow of the cooling water to the condensing part (110B) by closing the cooling water flow path (30);
Control means (102) for controlling the opening and closing of the valve (31),
The control means (102) closes the valve (31) when the exhaust heat of the exhaust gas is to be transported again to the cooling water after the heat transport amount is regulated by the thermal switch function. A featured exhaust heat recovery device.   The said control apparatus (102) determines the regulation state of the said heat transport amount by the said heat switch function by the inlet-and-outlet temperature difference (Tw2-Tw1) of the said cooling water in the said condensation part (110B), Item 2. An exhaust heat recovery apparatus according to Item 1. The valve (31) is provided with a minute hole (31b),
The exhaust heat according to claim 2, wherein when the valve (31) is closed, the cooling water flows through the cooling water flow path (30) in a minute amount by the minute hole (31b). Recovery device.   The control device (102) determines the state of regulation of the heat transport amount by the thermal switch function, the temperature difference of the exhaust gas in the exhaust gas in the evaporation unit (110A), or the evaporation unit (in the heat pipe (110)). 110. The exhaust heat recovery apparatus according to claim 1, wherein the determination is made based on a difference in surface temperature between 110A) and the condensing part (110B).   The exhaust according to any one of claims 1 to 4, wherein the control means (102) closes the valve (31) when an exhaust heat amount of the exhaust gas is smaller than a predetermined heat amount. Heat recovery device.   The exhaust heat according to claim 5, wherein the control means (102) grasps the exhaust heat amount of the exhaust gas from the temperature (Tg1) of the exhaust gas or the rotational speed of the internal combustion engine (10). Recovery device.   The control means (102) closes the valve (31) when the pressure in the heat pipe (110) is lower than a predetermined pressure, according to any one of claims 1 to 4. The exhaust heat recovery apparatus described. The evaporation section (110A) is disposed in the exhaust pipe (11) for exhaust gas flow of the internal combustion engine (10) for the hybrid vehicle, and the condensing section (110B) is a cooling water flow for cooling water flow of the internal combustion engine (10). The condensing unit is arranged in the passage (30) and according to the increase in the heating amount to the evaporation unit (110A) or the temperature of the cooling water of the internal combustion engine (10) flowing into the condensing unit (110B). (110B) having a heat pipe (110) with a heat switch function that regulates the amount of heat transport to
In the exhaust heat recovery apparatus for transporting exhaust heat of the exhaust gas to the cooling water by the heat pipe (110),
Control means (102A) for stopping the internal combustion engine (10) is provided when it is desired to transport the exhaust heat of the exhaust gas to the cooling water again after the amount of heat transport is regulated by the heat switch function. An exhaust heat recovery apparatus characterized by that.

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