JP6205867B2 - Engine waste heat utilization device - Google Patents

Description

  The present invention relates to an engine waste heat utilization device, and more particularly, to a combination of a Rankine cycle and a supercharger intercooler.

  There is a combination of a Rankine cycle and a turbocharger intercooler (see Patent Document 1). This system introduces high-temperature and high-pressure intake air from the turbocharger into the heat exchanger, conducts heat exchange with the Rankine cycle refrigerant, guides the refrigerant whose temperature has risen to the expander, and exits the expander. The refrigerant is condensed with an air-cooled condenser. On the other hand, the intake air whose temperature has been lowered by the heat exchanger is further led to an air-cooled intercooler for cooling.

JP 2008-8224 A

  By the way, in order to combine the Rankine cycle and the supercharger, both the Rankine cycle condenser and the intercooler for the supercharger are changed to liquid cooling, and the cooling liquid is allowed to flow through the liquid cooling condenser and the liquid cooling intercooler. When the present inventor first came to mind, it was found that the following merits occur. That is, the heat dissipation of the water-cooled condenser in the Rankine cycle is dominant in the non-supercharging region, whereas the heat dissipation of the water-cooled intercooler is dominant in the supercharging region. If the heat radiation of the water-cooled condenser and the heat radiation of the water-cooled intercooler do not overlap with each other under load conditions, the second heat exchanger that cools the cooling liquid can be used as the heat radiation of the water-cooled intercooler in the supercharging area and the non-supercharging area. Therefore, it is not necessary to have a heat dissipating capacity that covers the total heat dissipated by the water-cooled condenser.

  However, such knowledge is not described in Patent Document 1 at all.

  Therefore, the present invention combines the Rankine cycle and the supercharger by using both the condenser and the intercooler as liquid cooling, and the heat dissipation capability of the second heat exchanger for cooling the coolant flowing through the two members can be kept small. An object is to provide a heat utilization device.

The engine waste heat utilization device of the present invention includes a heat exchanger that recovers engine waste heat into a refrigerant through engine cooling water, an expander that generates power using the refrigerant at the outlet of the heat exchanger, and the expansion A condenser for condensing the refrigerant leaving the machine, a Rankine cycle including a refrigerant pump for supplying the refrigerant from the condenser to the heat exchanger, a supercharger for supercharging intake air, and supercharging by the supercharger And an intercooler for cooling the intake air. In the engine waste heat utilization device according to the present invention, the condenser is a liquid-cooled condenser that condenses the refrigerant that has exited the expander by heat exchange with a coolant, and the intercooler performs heat exchange with the coolant. A liquid-cooled intercooler that cools the intake air by using the liquid-cooled condenser, the liquid-cooled intercooler, a second heat exchanger that cools the coolant, and a coolant that exits the second heat exchanger. Is connected to the pump through a coolant passage that forms a circuit independent of the engine coolant .

  In the non-supercharging region on the low and medium load side, the heat dissipation of the liquid-cooled condenser of the Rankine cycle is dominant, but in the supercharging region on the high load side, the heat dissipation of the liquid cooling intercooler is dominant. Thus, when the heat radiation of the liquid-cooled condenser of the Rankine cycle and the heat radiation of the liquid-cooled intercooler do not overlap with each other under load conditions, the heat radiation of the liquid-cooled intercooler in the supercharged area and the liquid-cooled condenser in the non-supercharged area Since it is not necessary to provide a second heat exchanger with a heat dissipation capacity that covers the total of the heat dissipation, the present invention makes both the Rankine cycle condenser and the intercooler liquid-cooled, and this liquid-cooled condenser, Since the liquid cooling intercooler, the second heat exchanger that cools the cooling liquid, and the pump that discharges the cooling liquid exiting the second heat exchanger are connected by the cooling liquid passage through which the cooling liquid circulates, the second heat As the exchanger, a second heat exchanger having a heat radiation capacity smaller than the sum of the heat radiation of the liquid cooling intercooler in the supercharging region and the heat radiation of the liquid cooling condenser in the non-supercharging region is sufficient. Thereby, the heat dissipation capability of the second heat exchanger can be effectively utilized, and the heat dissipation capability shortage and the increase in size of the second heat exchanger can be avoided.

It is a schematic structure figure showing the whole system of a Rankine cycle of a 1st embodiment of the present invention. It is a schematic sectional drawing of the expander pump which integrated the pump and the expander. It is a schematic sectional drawing of a refrigerant pump. It is a schematic sectional drawing of an expander. It is a characteristic view of the heat dissipation of a 2nd cooling water circuit, a water cooling condenser inlet refrigerant | coolant temperature, and a water cooling intercooler inlet air temperature. It is a characteristic view of a water cooling intercooler inlet cooling water temperature. It is a flowchart for demonstrating control of the expander clutch of 1st Embodiment. It is a schematic block diagram showing the whole system of Rankine cycle of a 2nd embodiment. It is a flowchart for demonstrating the control at the time of expansion machine clutch fixation of 2nd Embodiment. It is a schematic block diagram showing the whole system of Rankine cycle of a 3rd embodiment. It is the schematic block diagram which took out only the 2nd cooling water circuit from FIG. It is a flowchart for demonstrating the control at the time of expansion machine clutch fixation of 3rd Embodiment. It is a schematic block diagram of the 2nd cooling water circuit of 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing the entire Rankine cycle system according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an expander pump in which a refrigerant pump and an expander are integrated.

  In FIG. 1, the engine 2 includes an exhaust passage 3, and the exhaust passage 3 includes an exhaust manifold 4 and an exhaust pipe 5 connected to a collecting portion of the exhaust manifold 4.

  First, the engine coolant circuit will be described. The cooling water of about 80 to 90 ° C. leaving the engine 2 flows separately into a cooling water passage 13 that passes through the radiator 11 and a bypass cooling water passage 14 that bypasses the radiator 11. Thereafter, the two flows are merged again by a thermostat valve 15 that determines the distribution of the flow rate of the cooling water flowing through both passages 13 and 14, and then returns to the engine 2 via the cooling water pump 16. The cooling water pump 16 is driven by the engine 2 and its rotation speed is synchronized with the engine rotation speed.

  The thermostat valve 15 relatively increases the amount of cooling water passing through the radiator 11 by increasing the valve opening on the cooling water passage 13 side when the cooling water temperature is high. When the cooling water temperature is low, the valve opening on the cooling water passage 13 side is decreased to relatively reduce the amount of cooling water passing through the radiator 11. When the coolant temperature is particularly low, such as before the engine 2 is warmed up, the radiator 11 is completely bypassed and the entire amount of coolant flows through the bypass coolant passage 14 side. On the other hand, the valve opening on the bypass cooling water passage 14 side is not fully closed, and when the flow rate of the cooling water flowing through the radiator 11 is increased, the flow rate of the cooling water flowing through the bypass cooling water passage 14 is Is reduced as compared with the case where the total amount of the refrigerant flows through the bypass cooling water passage 14 side. In this case, the thermostat valve 15 is configured so that the flow does not stop completely.

  The bypass cooling water passage 14 includes an evaporator 26 that exchanges heat with the refrigerant of the Rankine cycle 21. That is, the evaporator 26 is provided with a cooling water passage 26a and a refrigerant passage 26b through which the refrigerant of the Rankine cycle 21 flows so as to exchange heat between the refrigerant and the cooling water. Furthermore, the passages 26a and 26b are configured so that the refrigerant and the cooling water in the Rankine cycle 21 are in opposite directions when viewed from the whole evaporator 26.

  Specifically, the cooling water passage 26 a is interposed in the bypass cooling water passage 14 for the refrigerant of the Rankine cycle 21. The evaporator 26 composed of the cooling water passage 26a and the refrigerant passage 26b adjacent to the cooling water passage 26a introduces the cooling water from the engine 2 into the cooling water passage 26a, so that the Rankine that flows through the refrigerant passage 26b. This is for heating the refrigerant of the cycle 21.

  If the temperature of the cooling water from the bypass cooling water passage 14 toward the thermostat valve 15 is sufficiently lowered, for example, by exchanging heat with the refrigerant of the Rankine cycle 21 by the evaporator 26, the cooling water passage 13 side of the thermostat valve 15 is provided. The valve opening is reduced. As a result, the amount of cooling water passing through the radiator 11 is relatively reduced. On the contrary, if the temperature of the cooling water from the bypass cooling water passage 14 toward the thermostat valve 15 becomes high due to the Rankine cycle 21 not being operated, the valve opening degree of the thermostat valve 15 on the cooling water passage 13 side is increased. The Thereby, the amount of cooling water passing through the radiator 11 is relatively increased. Based on such operation of the thermostat valve 15, the coolant temperature of the engine 2 is appropriately maintained, and heat is appropriately supplied (recovered) to the Rankine cycle 21.

  Next, the Rankine cycle 21 of the basic invention as a premise of the present invention will be described. The Rankine cycle 21 of the basic invention is a system that recovers waste heat of the engine 2 to a refrigerant through the cooling water of the engine 2 and regenerates the recovered waste heat as power, and has not been disclosed at the time of filing of the present invention. The Rankine cycle 21 includes a refrigerant pump 22, an evaporator 26, an expander 27, and an air-cooled condenser (condenser) 28, and each component is connected by refrigerant passages 31 to 34 through which a refrigerant (R134a and the like) circulates. Although the condenser 28 shown in FIG. 1 is a water-cooled condenser, the condenser according to the basic invention is an air-cooled condenser and will be described as an air-cooled condenser.

  As shown in FIG. 2, the shaft 22a of the refrigerant pump 22 is connected to the output shaft 27a of the expander 27 on the same shaft, and drives the refrigerant pump 22 by the output (power) generated by the expander 27. The generated power is supplied to the output shaft (crankshaft) of the engine 2. That is, as shown in FIG. 1, the shaft 22a of the refrigerant pump 22 and the output shaft 27a of the expander 27 are arranged in parallel with the output shaft of the engine 2, and the pump pulley 23 provided at the tip of the shaft 22a of the refrigerant pump 22; A belt 24 is wound around the crank pulley 2a. Note that a gear type pump is used as the refrigerant pump 22 of the present embodiment, and a scroll type expander is used as the expander 27 (see FIGS. 3 and 4).

  Further, an electromagnetic clutch (hereinafter referred to as “expander clutch”) 25 is provided between the pump pulley 23 and the refrigerant pump 22 so that the refrigerant pump 22 and the expander 27 can be connected to and disconnected from the engine 2. (See FIG. 2). For this reason, when the output generated by the expander 27 exceeds the driving force of the refrigerant pump 22 and the friction of the rotating body, the expander clutch 25 is connected to rotate the engine output shaft by the output generated by the expander 27. Can be assisted. Thus, fuel efficiency can be improved by assisting rotation of an engine output shaft using energy obtained by waste heat recovery. Further, the energy for driving the refrigerant pump 22 for circulating the refrigerant can also be covered by the recovered waste heat.

  The refrigerant from the refrigerant pump 22 is supplied to the evaporator 26 via the refrigerant passage 31. The evaporator 26 is a heat exchanger that causes heat exchange between the coolant of the engine 2 and the refrigerant, and vaporizes and heats the refrigerant.

  The refrigerant from the evaporator 26 is supplied to the expander 27 through the refrigerant passage 32. The expander 27 is a steam turbine that converts heat into rotational energy by expanding a vaporized and heated refrigerant. The power recovered by the expander 27 drives the refrigerant pump 22 and is transmitted to the engine 2 via the belt transmission mechanism to assist the rotation of the engine 2.

  The refrigerant from the expander 27 is supplied to the air-cooled condenser 28 through the refrigerant passage 33. The air-cooled condenser 28 is a heat exchanger that causes heat exchange between the outside air and the refrigerant to cool and liquefy the refrigerant. For this reason, the air-cooled condenser 28 is arranged in parallel with the radiator 11 and is cooled by the radiator fan 12. The condenser 28 described here is an air-cooled type because it is used in the basic invention. However, in this embodiment, the water-cooled condenser 28 is configured instead of the air-cooled condenser as will be described later.

  The refrigerant liquefied by the air-cooled condenser 28 is returned to the refrigerant pump 22 through the refrigerant passage 34. The refrigerant returned to the refrigerant pump 22 is sent again to the evaporator 26 by the refrigerant pump 22 and circulates through each component of the Rankine cycle 21.

  The Rankine cycle 21 is appropriately provided with various valves in the middle of the circuit in order to control the refrigerant flowing in the cycle. For example, in order to control the refrigerant circulating in the Rankine cycle 21, the pump upstream valve 51 is connected to the refrigerant passage 34 connecting the condenser 28 and the refrigerant pump 22, and the refrigerant passage 32 is connected to the evaporator 26 and the expander 27. A machine upstream valve 52 is provided. The refrigerant passage 31 that connects the refrigerant pump 22 and the evaporator 26 is provided with a check valve 53 to prevent the refrigerant from flowing backward from the evaporator 26 to the refrigerant pump 22. The refrigerant passage 33 that connects the expander 27 and the condenser 28 is also provided with a check valve 54 to prevent the refrigerant from flowing backward from the condenser 28 to the expander 27. Further, an expander bypass passage 55 that bypasses the expander 27 from the upstream of the expander upstream valve 52 and merges upstream of the check valve 54 is provided, and a bypass valve 56 is provided in the expander bypass passage 55. Further, a pressure regulating valve 58 is provided in a passage 57 that bypasses the bypass valve 56.

  The three valves 51, 52, and 56 are all electromagnetic on-off valves. An expander upstream pressure signal detected by the pressure sensor 62, a refrigerant pressure Pd signal at the outlet of the condenser 28 detected by the pressure sensor 63, a rotation speed signal of the expander 27, and the like are input to the engine controller 61. . The engine controller 61 controls the radiator fan 12 and controls the opening and closing of the three electromagnetic on-off valves 51, 52, and 56 based on these input signals in accordance with predetermined operating conditions.

  For example, the expander torque (regenerative power) is predicted based on the expander upstream pressure detected by the pressure sensor 62 and the expander rotational speed, and when the predicted expander torque is positive (assist rotation of the engine output shaft). The expander clutch 25 is engaged. On the other hand, the expander clutch 25 is released when the predicted expander torque is zero or negative. Based on the sensor detection pressure and expander rotational speed, the expander torque can be predicted with higher accuracy than when the expander torque (regenerative power) is predicted from the exhaust temperature. Accordingly, the expander clutch 25 can be appropriately engaged and released. This completes the description of the Rankine cycle 21 of the basic invention.

  Next, the engine 2 includes a turbocharger 81 (supercharger). The turbocharger 81 is obtained by coaxially connecting an exhaust turbine 82 and an intake compressor 83. Here, the exhaust turbine 82 is rotationally driven by the energy of the exhaust gas flowing through the exhaust pipe 5. An intake compressor 83 interposed in the intake pipe 6 upstream of the throttle valve 7 compresses and discharges the intake air. A waste gate valve 87 for opening and closing the passage 86 is provided in the passage 86 that bypasses the exhaust turbine 82.

  Since the intake air compressed by the intake compressor 83 becomes high temperature and high pressure, an air cooling intercooler 85 for cooling the intake air that has become high temperature and high pressure is provided in the intake pipe 6 between the intake compressor 83 and the throttle valve 7. . Although the intercooler 85 is described as being air-cooled here, in this embodiment, as will be described later, the air-cooled intercooler is replaced with a water-cooled intercooler.

  There is a conventional device that combines a Rankine cycle and a turbocharger air-cooled intercooler.

  Here, in order to combine the Rankine cycle 21 and the turbocharger 81, the air-cooled condenser 28 and the air-cooled intercooler 85 of the Rankine cycle 21 are both changed to water cooling (liquid cooling), and cooling water is supplied to these water-cooled condenser and water-cooled intercooler. When the inventor first came up with the idea, the following benefits were found. That is, the heat dissipation of the water-cooled condenser of the Rankine cycle 21 is dominant in the non-supercharging region, whereas the heat dissipation of the water-cooled intercooler is dominant in the supercharging region. If the heat radiation of the water-cooled condenser and the heat radiation of the water-cooled intercooler do not overlap with each other under load conditions, the sub-radiator (second heat exchanger) that cools the cooling water can have the heat radiation of the water-cooled intercooler in the supercharging region. A heat dissipating capacity that covers the total of the heat dissipated by the water-cooled condenser in the non-supercharging region is not necessary. However, such knowledge is not described in the conventional apparatus.

  Therefore, based on the knowledge of the present inventor, in the first embodiment of the present invention, the air-cooled condenser 28 and the air-cooled intercooler 85 used in the Rankine cycle 21 of the basic invention are changed to water-cooled, and the water-cooled condenser and the water-cooled intercooler are changed. The included cooling water circuit 91 is configured independently of the engine cooling water circuit. This coolant circuit 91 is referred to as a “second coolant circuit” in order to distinguish it from the engine coolant circuit described above. In addition, as a code | symbol attached | subjected to the water-cooled condenser and water-cooled intercooler which are respectively used for the Rankine cycle of 1st Embodiment, the code | symbol attached | subjected to the air-cooled condenser 28 and the air-cooled intercooler 85 which are respectively used for the Rankine cycle 21 of basic invention. Shall be given the same reference numerals.

  The second cooling water circuit 91 includes a water cooling condenser 28, a water cooling intercooler 85, a sub-radiator 92 (second condenser), and a cooling water pump 93, and cooling water passages 95 to 97 through which cooling water circulates through each component. Connect with.

  The sub radiator 92 is arranged in parallel with the radiator 11, and the cooling water in the sub radiator 92 is cooled by the radiator fan 12. The cooling water cooled by the sub radiator 92 is supplied to the water cooling intercooler 85 by the cooling water pump 93. The cooling water pump 93 is interposed in a cooling water passage 95 connecting the sub radiator 92 and the water cooling intercooler 85. The cooling water pump 93 is driven by a motor 94 that receives a command from the engine controller 61.

  The water-cooled intercooler 85 cools the intake air that has become high temperature and high pressure by the intake air compressor 83 by exchanging heat with cooling water. The cooled intake air is metered by the throttle valve 7 and then stored in the collector 8 and distributed from the intake manifold to the combustion chamber of each cylinder.

  On the other hand, the cooling water whose temperature has been raised by the water-cooled intercooler 85 is supplied to the water-cooled condenser 28 via the cooling water passage 96 connecting the water-cooled intercooler 85 and the water-cooled condenser 28. The water-cooled condenser 28 is a heat exchanger that causes heat exchange between the refrigerant from the expander 27 and the cooling water to cool and liquefy the refrigerant in the Rankine cycle 21. The cooling water whose temperature has been raised by the water-cooled condenser 28 is returned to the sub-radiator 92 via the cooling water passage 97 connecting the water-cooled condenser 28 and the sub-radiator 92, and is cooled by the sub-radiator 92. The cooling water cooled by the sub-radiator 92 is discharged by the cooling water pump 93, and the cooling water passages 95, 96, and 97 are circulated again.

  Next, why both the air-cooled condenser and the air-cooled intercooler of the Rankine cycle 21 are changed to water cooling, and the reason why the second cooling water circuit 91 that circulates to the water-cooled condenser 28 and the water-cooled intercooler 85 is configured is shown in FIG. Further explanation will be given.

  FIG. 5A is a characteristic diagram of the heat radiation amount of the second cooling water circuit 91 under a condition where the engine rotation speed is constant. Similarly, FIG. 5B is a characteristic diagram in which the refrigerant temperature at the inlet of the water-cooled condenser and the intake air temperature at the inlet of the water-cooled intercooler are overlapped under a condition where the engine speed is constant. First, the heat radiation amount of the second cooling water circuit 91 is the sum of the heat radiation amount of the water-cooled condenser 28 and the heat radiation amount of the water-cooled intercooler 85. FIG. The individual heat dissipation amounts of the cooler 85 are described in an overlapping manner. That is, when the engine torque range is roughly divided into three engine torque ranges of low, medium and high, the Rankine cycle 21 is operated mainly in the low and medium engine torque range (low and medium load range). For this reason, as the engine torque increases, the heat dissipation amount of the water-cooled condenser 28 gradually increases as the engine torque increases, and the degree of increase decreases as the engine torque increases.

  On the other hand, supercharging by the turbocharger 81 is effective only in a high engine torque region (that is, a supercharging region) where the engine torque is equal to or greater than a predetermined value a. For this reason, in the engine torque range (that is, the non-supercharging region) smaller than the predetermined value a, the heat radiation amount of the water-cooled intercooler 85 is much smaller than the heat radiation amount of the water-cooled condenser 28, and becomes the supercharging region. The amount of heat released from the cooler 85 increases rapidly. The heat dissipation amount of the water-cooled intercooler 85 intersects with the heat dissipation amount of the water-cooled condenser 28 when the engine torque is a predetermined value b, and exceeds the heat dissipation amount of the water-cooled condenser 28 in the engine torque region of the predetermined value b or more.

  Next, in FIG. 5B, the parameters on the horizontal axis are the same as those in FIG. The refrigerant temperature at the inlet of the water-cooled condenser increases with an increase in engine torque from 40 ° C. to 50 ° C., and rapidly rises to 150 ° C. to 200 ° C. in the supercharging region. On the other hand, the intake air temperature at the inlet of the water-cooled intercooler is lower than the coolant temperature at the inlet of the water-cooled condenser in the non-supercharging region, and rapidly rises when the supercharging region is reached. For this reason, when the engine torque is a predetermined value c, the water-cooled intercooler inlet intake temperature and the water-cooled condenser inlet refrigerant temperature cross each other, and the water-cooled intercooler inlet air temperature is the water-cooled condenser inlet refrigerant temperature in the engine torque range equal to or greater than the predetermined value c. Is over.

  FIG. 5 (a) shows the heat dissipation characteristics of the water-cooled condenser 28, and FIG. 5 (a) shows the characteristics of the water-cooled condenser inlet refrigerant temperature until the engine torque is maximized. The Rankine cycle 21 is not operated in the engine torque range. The Rankine cycle 21 is not operated on the high engine torque side, and the Rankine cycle 21 is operated only in the low and middle engine torque regions.

  5 (a) and 5 (b), the heat dissipation of the water-cooled intercooler 85 is dominant in the supercharging region where the engine torque is greater than or equal to the predetermined value a, whereas the engine torque is less than the predetermined value a. The heat radiation of the water-cooled condenser 28 is dominant in the supercharging region. That is, the heat radiation of the water-cooled condenser 28 and the heat radiation of the water-cooled intercooler 85 do not overlap with each other in the engine torque condition (load condition). For this reason, if the sub-radiator 92 having a heat radiation capacity corresponding to the maximum heat radiation amount of the water-cooled intercooler 85 is provided, the water-cooled condenser 28 can radiate heat in a low and middle engine torque region where the water-cooled intercooler 85 does not work. It is not necessary to provide a sub-radiator having a heat radiation capacity corresponding to the heat radiation amount obtained by simply summing the heat radiation amounts of the water-cooled condenser 28 and the water-cooled intercooler 85, and a heat radiation capacity sub-capacity corresponding to the maximum heat radiation amount of the water-cooled intercooler 85 is not required. It is sufficient to provide the radiator 92.

  As described above, in the present embodiment, the heat exchanger 26 that recovers the waste heat of the engine 2 into the refrigerant, the expander 27 that generates power using the refrigerant at the outlet of the heat exchanger 26, and the expander 27 are exited. A condenser 28 that condenses the refrigerant, a Rankine cycle 21 including a refrigerant pump 22 that supplies the refrigerant from the condenser 28 to the heat exchanger 26, a turbocharger 81 (supercharger) that supercharges intake air, and a turbocharger An intercooler 85 that cools the intake air supercharged by 81, and the condenser 28 is a water-cooled condenser that condenses the refrigerant exiting the expander 27 by heat exchange with cooling water (coolant), The intercooler 85 is a water-cooled intercooler that cools the intake air by heat exchange with cooling water (cooling liquid). The water-cooled liquid cooling condenser 28, the water-cooling intercooler 85, and cooling water (cooling) Cooling water passages 95 to 97 through which cooling water circulates through a sub-radiator 92 (second heat exchanger) that cools the liquid) and a cooling water pump 98 (a pump that discharges the cooling liquid that has exited the second heat exchanger). (Cooling liquid passage) As shown in FIGS. 5 (a) and 5 (b), the heat dissipation of the liquid-cooled condenser 28 in the Rankine cycle is dominant in the non-supercharged region, whereas the water-cooled intercooler 85 is in the supercharged region. Heat dissipation becomes dominant. Thus, when the heat radiation of the water-cooled condenser 28 in the Rankine cycle and the heat radiation of the water-cooled intercooler 85 do not overlap in the load condition, the heat radiation of the water-cooled intercooler 85 in the supercharging region and the water-cooled condenser 28 in the non-supercharged region. Since it is not necessary to provide the sub-radiator 92 having a heat radiation capacity that covers the total heat radiation of the water, the condenser 28 and the intercooler 85 of the Rankine cycle 21 are both water-cooled according to this embodiment. 28, the water-cooled intercooler 85, the sub-radiator 92, and the cooling water pump 93 are connected by the cooling water passages 95 to 97. Therefore, the sub-radiator 92 is configured to dissipate heat from the water-cooled intercooler 85 in the supercharging region. A sub radiator 92 having a heat radiation capacity smaller than the total heat radiation of the water-cooled condenser 28 in the supercharging region is sufficient. Thus, the heat dissipation capability of the sub radiator 92 can be effectively utilized, and the heat dissipation capability of the sub radiator 92 can be prevented from being insufficient or enlarged.

  Next, FIG. 6 is a characteristic diagram of the cooling water temperature at the inlet of the water-cooled intercooler. When the cooling water flows in the order of the water-cooled condenser 28 and the water-cooled intercooler 85, the one-dot broken line shows the water-cooled intercooler 85 and the water-cooled condenser 28. The case where the cooling water is flowed in this order is shown by overlapping with a solid line. As shown in FIG. 1, when cooling water flows in the order of the water-cooled intercooler 85 and the water-cooled condenser 28, the cooling water having the lowest temperature that has flowed out of the sub-radiator 92 flows first into the water-cooled intercooler 85. For this reason, the coolant temperature at the inlet of the water-cooled intercooler hardly increases in the non-supercharging region where the engine torque is less than the predetermined value a as shown by the solid line in FIG. Rise after entering the area.

  On the other hand, when the cooling water is supplied in the order of the water-cooled condenser 28 and the water-cooled intercooler 85, the cooling water whose temperature has been increased by the heat radiation of the water-cooled condenser 28 in the non-supercharging region flows to the water-cooled intercooler 85. As a result, the coolant temperature at the inlet of the water-cooled intercooler rises from the coolant temperature at the inlet of the water-cooled intercooler when the coolant is passed in the order of the water-cooled intercooler 85 and the water-cooled condenser 28 as shown by the one-dot chain line in FIG. In the supercharging region, the intake air temperature rises by an amount corresponding to the rise of the water cooling intercooler inlet cooling water temperature, so that the working gas temperature rises and knocking tends to occur, and the fuel consumption and output of the engine deteriorate.

  As described above, according to the present embodiment, the water-cooled intercooler 85 and the water-cooled condenser 28 are provided in series, and the cooling water at the outlet of the sub-radiator 92 flows in the order of the water-cooled intercooler 85 and the water-cooled condenser 28 from the upstream. For example, if the accelerator pedal is suddenly depressed, the heat-cooling intercooler 85 and the water-cooled condenser 28 temporarily overlap heat dissipation during acceleration when the Rankine cycle 21 shifts from the operating region (non-supercharging region) to the supercharging region. In addition, the cooling performance of the water-cooled intercooler 85 can be secured.

  Next, the flow of FIG. 7 is for the engine controller 61 to control the expander clutch 25, and is executed at regular intervals (for example, every 10 ms).

  In step 1, the refrigerant temperature T1 at the water-cooled condenser inlet is detected by the temperature sensor 65 (see FIG. 1), and in step 2, the intake air temperature T2 at the water-cooled intercooler inlet is detected by the temperature sensor 66 (see FIG. 1).

  In Step 3, the two temperatures T1 and T2 are compared, and when the refrigerant temperature T1 at the water-cooled condenser inlet is equal to or lower than the intake air temperature T2 at the water-cooled intercooler inlet, the process proceeds to Step 4 and the expander clutch 25 is operated to operate the Rankine cycle. Connected. When the expander clutch 25 is in the connected state, the refrigerant pump 22 is driven by the engine 2. Here, in the electromagnetic clutch as the expander clutch 25, an electromagnetic force is generated by energizing a solenoid coil (not shown), and the two members are pressure-bonded by this electromagnetic force to bring the clutch into a connected state. Further, assuming that the electromagnetic clutch is disengaged by stopping energization of the solenoid coil and eliminating the electromagnetic force, the solenoid coil may be energized to place the expander clutch 25 in the connected state.

  On the other hand, when the water-cooled intercooler inlet intake temperature T2 becomes higher than the water-cooled condenser inlet refrigerant temperature T1 in step 3, the process proceeds to step 5 where the refrigerant pump 22 is stopped by disconnecting the expander clutch 25. If the refrigerant pump 22 stops, the operation of the Rankine cycle 21 stops. In order to disconnect the expander clutch 25, the energization of the solenoid coil may be stopped. When the expander clutch 25 is disconnected, the rotation of the shaft 22a of the refrigerant pump 22 stops, so the refrigerant pump 22 stops and the operation of the Rankine cycle 21 stops. Here, T2 is higher than T1 in the supercharging region as shown in FIG. 5B.

  From FIG. 5B, when the Rankine cycle 21 is operated even in the supercharging region, the water-cooled condenser 28 radiates heat. Since the heat radiation capacity of the sub-radiator 92 is limited, not all heat radiation of the water-cooled condenser 28 performed in the supercharging region can be heat-exchanged. Therefore, the cooling water temperature at the outlet of the sub-radiator 92 increases correspondingly, and the intercooler 92 Will disturb the heat dissipation. Therefore, in the present embodiment, the expansion device clutch 25 is disconnected when T2 becomes higher than T1, so that the heat radiation of the water-cooled intercooler in the supercharging region is not disturbed.

  As described above, according to this embodiment, the expander clutch 25 that connects and disconnects the conduction of the rotational force from the expander 27 to the engine 2 is provided, and the refrigerant temperature T1 is higher than the refrigerant temperature T1 at the inlet of the water-cooled condenser 28 (liquid-cooled condenser). When the intake air temperature T2 at the inlet of the water-cooled intercooler 85 (liquid-cooled intercooler) becomes higher, the refrigerant pump 22 is stopped by disengaging the expander clutch 25 (see steps 3 and 5 in FIG. 7). 21 stops and the water-cooled condenser 28 dissipates heat. Thereby, the heat radiation of the water-cooled condenser 28 does not interfere with the heat radiation of the water-cooled intercooler 85, and the water-cooled intercooler 85 can be efficiently operated in the supercharging region.

(Second Embodiment)
FIG. 8 is a schematic configuration diagram showing the whole Rankine cycle system of the second embodiment, which replaces FIG. 1 of the first embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals.

  In the first embodiment, the expander clutch 25 is disconnected when the intake air temperature T2 at the water-cooled intercooler inlet becomes higher than the refrigerant temperature T1 at the water-cooled condenser inlet. I tried to work efficiently. However, sticking may occur where the expander clutch 25 is always connected. When the expander clutch 25 is stuck, the expander clutch 25 cannot be disconnected. If the expander clutch 25 cannot be disconnected, the water-cooled condenser 25 continues to dissipate heat even when the supercharging region is reached. Then, the heat radiation of the water-cooled condenser 28 interferes with the heat radiation of the water-cooled intercooler 85, and the water-cooled intercooler 85 cannot be efficiently operated in the supercharging region. If the water-cooled intercooler 85 cannot be operated efficiently in the supercharging region, knocking tends to occur due to the high temperature of the working gas, and the fuel consumption and output of the engine deteriorate.

  Therefore, in the second embodiment, the supercharging by the turbocharger 81 (supercharger) is stopped when the expander clutch 25 is fixed so as to be always connected.

  Specifically, the flow of FIG. 9 is for the engine controller 61 to stop the supercharging by the turbocharger 81 when the expander clutch 25 is stuck, and is executed at regular intervals (for example, every 10 ms). To do.

  In FIG. 9, it is determined whether or not the expander clutch 25 is stuck in step 11. Here again, in the electromagnetic clutch as the expander clutch 25, an electromagnetic force is generated by energizing the solenoid coil, and the two members are pressure-bonded by this electromagnetic force to bring the clutch into a connected state. Further, it is assumed that the electromagnetic clutch is disengaged by stopping energization of the solenoid coil and eliminating the electromagnetic force. At this time, when a large input such as a slip input is input to the electromagnetic clutch, the two members may stick to each other or stick to each other, and the clutch is rarely fixed. Further, the clutch may be stuck due to deterioration with time. In addition, since energization and de-energization of the solenoid coil is performed by a relay, a clutch lock state may occur due to a failure of the relay.

  Whether or not the expander clutch 25 is stuck may be based on the pump shaft rotational speed sensor 101 (see FIG. 9) that detects the rotational speed of the refrigerant pump shaft 22a. That is, since the Rankine cycle 21 is not operated in the supercharging region, the expander clutch 25 is disconnected by stopping the energization of the solenoid coil. Therefore, if the refrigerant pump shaft 22a is rotating even in the supercharging region where the Rankine cycle 21 is not operated, the expander clutch 25 is stuck. Therefore, if the rotational speed Npmp detected by the pump shaft rotational speed sensor 101 is not zero in the supercharging region where the Rankine cycle 21 is not operated, it can be determined that the expander clutch 25 is stuck. This determination result, that is, information (data) indicating whether or not the expander clutch 25 is stuck is stored in the memory. Then, in step 11, if this information is seen and the expander clutch 25 is not fixed, the current process is terminated.

  When the expander clutch 25 is stuck in step 11, the process proceeds to step 12 where a waste gate valve 87 (see FIG. 8) provided in the passage 86 that bypasses the exhaust turbine 82 is used to stop supercharging by the turbocharger 81. )open. Similarly, in the case of the supercharger 121 described later in the fourth embodiment (see FIG. 13), the supercharger 121 is operated by turning off (disconnecting) the electromagnetic clutch 123 or fully opening the bypass valve 125. Stop supercharging. The method of stopping the supercharging is not limited to this. For example, the supercharging by the turbocharger 81 or the supercharger 121 can be stopped by restricting the opening degree of the throttle valve 7 on the fully open side so that the supercharging region is not used.

  As described above, according to the second embodiment, the supercharge by the turbocharger 81 (supercharger) is stopped when the expander clutch 25 is fixed so as to be always connected (see steps 11 and 12 in FIG. 9). ) Even when the expander clutch 25 is fixed, knocking associated with the operation of the turbocharger 81 can be suppressed, and deterioration of fuel consumption and output of the engine can be suppressed.

(Third embodiment)
FIG. 10 is a schematic configuration diagram showing the entire Rankine cycle system of the third embodiment, which replaces FIG. 1 of the first embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals.

  Here, in order to make it easy to see the configuration in which the water-cooled condenser 28 and the water-cooled intercooler 85 are connected in parallel, FIG. 11 shows a schematic configuration diagram in which only the second cooling water circuit 91 is taken out from FIG. The second cooling water circuit 91 ′ will be described with reference to FIG. 11. The cooling water passage 95 connected to the outlet of the sub radiator 92 is branched into two, and one branch cooling water passage 95 a is connected to the water cooling intercooler 85. The other branch cooling water passage 95 b is connected to the water cooling condenser 28. Further, the cooling water passage 97 connected to the inlet of the sub radiator 92 is branched into two, one branch cooling water passage 97a is connected to the water cooling intercooler 85, and the other branch cooling water passage 97b is connected to the water cooling condenser. When the water-cooled condenser 28 and the water-cooled intercooler 85 are connected in parallel in this way, the cooling water at the outlet of the cooling water pump 93 flows to the water-cooled condenser 28 and the water-cooled intercooler 85 via the branch cooling water passages 95a and 95b. .

  Thus, according to the third embodiment, the water-cooled intercooler 85 (liquid-cooled intercooler) and the water-cooled condenser 28 (liquid-cooled condenser) are provided in parallel, and the sub-radiator 92 (second heat Since the cooling water (coolant) at the outlet flows, the heat dissipation capability of the sub-radiator 92 is effectively utilized as in the first embodiment in which a water-cooled intercooler and a water-cooled condenser are provided in series. In addition, it is possible to avoid insufficient heat dissipation capability and increase in size of the sub radiator 92.

  Next, also in the third embodiment, a measure when the expander clutch is stuck is considered. That is, in the second embodiment, on the premise of the second cooling water circuit 91 in which the water-cooled condenser 28 and the water-cooled intercooler 85 are connected in series, supercharging by the turbocharger 81 is performed when the expander clutch 25 is stuck. Stopped. On the other hand, in the third embodiment, on the premise of the second cooling water circuit 91 ′ in which the water-cooled condenser 28 and the water-cooled intercooler 85 are connected in parallel, the water-cooled condenser 28 is fixed when the expander clutch 25 is fixed. Shut off the cooling water flow to the.

  In order to cut off the flow of the cooling water to the water-cooled condenser 28 when the expansion clutch is fixed so as to be always connected, a normally open on-off valve 111 is provided in the branch cooling water passage 95b. The on-off valve 111 is composed of, for example, an electromagnetic valve, and is fully closed when an ON signal is applied, and returns to a fully open state when an OFF signal is applied. A normally open on-off valve 111 may be provided in the branch cooling water passage 97b.

  The flow in FIG. 12 is for controlling the on-off valve 111 when the expander clutch 25 of the third embodiment is fixed, and is executed by the engine controller 61 at regular intervals (for example, every 10 ms).

  In step 21, it is determined whether or not the vehicle is in the supercharging region. Whether or not it is in the supercharging region may be determined based on the engine torque. For example, the engine torque is calculated based on the engine load, the calculated torque is compared with a predetermined value a, and if the calculated engine torque is equal to or greater than the predetermined value a, the calculated engine torque is If it is less than the value a, it is determined that it is in the non-supercharging region. Here, as a substitute value of the engine torque, an opening degree of an accelerator pedal or a basic injection pulse width used for fuel injection control in a gasoline engine may be used. If it is determined that the engine torque is not in the supercharging region, the current process is terminated.

  When it is determined in step 21 that the engine torque is in the supercharging region, the process proceeds to step 22 to check whether or not the expander clutch 25 is stuck in a constantly connected state. When the expander clutch 25 is not fixed, the process proceeds to step 23 to output an OFF signal to the on-off valve 111 to open the on-off valve 111 fully.

  When the expander clutch 25 is stuck in step 22, the process proceeds to step 24, where an ON signal is output to the on-off valve 111 and the on-off valve 111 is fully closed. Accordingly, in FIG. 11, the cooling water does not flow to the water-cooled condenser 28, so that the cooling water whose temperature has increased due to the heat radiation of the water-cooled condenser 28 is not returned to the sub-radiator 92.

  According to the third embodiment, the expander clutch 25 that connects / disconnects the transmission of the rotational force from the expander 27 to the engine 2 and the open / close valve that opens and closes the branch cooling water passage 95b (the coolant passage that flows through the liquid cooling condenser). 111, and the on-off valve 111 is closed when the expander clutch 25 is fixed so that the expander clutch 25 is always connected (see steps 22 and 24 in FIG. 12), the expander clutch 25 is fixed and the Rankine cycle 21 is closed. However, even if there is a heat recovery state and the water-cooled condenser 28 radiates heat, the cooling water does not flow through the water-cooled condenser 28, so the cooling water temperature does not rise. That is, since the heat radiation of the water-cooled condenser 28 does not interfere with the heat radiation of the water-cooled intercooler 85, the capacity of the sub radiator 92 can be prevented.

(Fourth embodiment)
FIG. 13 is a schematic configuration diagram of the second cooling water circuit 91 of the fourth embodiment. The same parts as those in FIG. 1 of the first embodiment are denoted by the same reference numerals. The Rankine cycle 21 is configured in the same manner as in the first embodiment, but only the water-cooled condenser 28 is shown in FIG.

  In the first embodiment, when the Rankine cycle 21 and the turbocharger 81 are combined, the condenser 28 and the intercooler 85 of the Rankine cycle 21 are both changed to water cooling, and the second cooling water circuit 91 is configured. . On the other hand, in the fourth embodiment, when the Rankine cycle 21 and the supercharger 121 (supercharger) are combined, the condenser 28 of the Rankine cycle 21 and the intercooler 85 for the supercharger are both changed to water cooling. The cooling water circuit 91 is configured.

  First, the configuration of the supercharger 121 will be briefly described. The supercharger 121 is provided in the intake pipe 6 upstream of the throttle valve 7 in FIG. Here, the supercharger 121 will be described using the Rishorum type, but is not limited to the Rishorum type. In order to drive the supercharger 121 by the engine 2, the belt 122 is wound around the pulley 121 a and the crankshaft pulley 2 a of the supercharger 121, and the rotational force of the crankshaft is transmitted to the pulley 121 a via the belt 122.

  An electromagnetic clutch 123 that is ON / OFF controlled by the engine controller 61 is provided between the pulley 121 a and the drive shaft 121 b of the supercharger 121. The electromagnetic clutch 123 may not be provided.

  A passage 124 for bypassing the supercharger 121 is provided, and the bypass passage 124 includes a bypass valve 125 capable of duty control controlled by the engine controller 61.

  The engine controller 61 operates the supercharger 121 by turning on the electromagnetic clutch 123 and fully closing the bypass valve 125. That is, when the electromagnetic clutch 123 is turned on and the pulley 121a and the drive shaft 121b are connected, a pair of twisted screw-shaped rotors rotate in the reverse direction inside the supercharger 121 to suck and discharge air ( Supercharged).

  Since the intake air compressed by the supercharger 121 becomes high temperature and high pressure, an air cooling intercooler 126 that cools the intake air that has become high temperature and high pressure is provided in the intake pipe 6 between the supercharger 121 and the throttle valve 7. .

  On the other hand, in order to stop the operation of the supercharger 121, the bypass valve 125 is fully opened while the electromagnetic clutch 123 is ON, or the electromagnetic clutch 123 is OFF.

  Even in the case of the engine 2 including the supercharger 121 configured as described above, by controlling the opening degree of the throttle valve 7 and the opening degree of the bypass valve 125 in a coordinated manner, more intake air is supplied to the combustion chamber in natural intake air. Supercharging by the supercharger 121 can be performed from the vicinity of the throttle valve opening that cannot be performed. At this time, the characteristics of the heat dissipation amount of the water-cooled intercooler 126 with respect to the engine torque and the intake air temperature of the water-cooled intercooler inlet are the same as those in FIGS. 5 (a) and 5 (b). Note that the usage of the supercharger 121 is not limited to this.

  In the fourth embodiment, when the supercharger 121 and the Rankine cycle 21 of the basic invention described above are combined, the air-cooled condenser 28 and the air-cooled intercooler 126 of the Rankine cycle 21 are changed to water-cooled, and the water-cooled condenser and water-cooled intercooler are changed. The 2nd cooling water circuit 91 containing is comprised. In addition, as a code | symbol attached | subjected to a water cooling condenser and a water cooling intercooler, the code | symbol same as the code | symbol attached to the air cooling condenser 28 and the air cooling intercooler 126 shall be attached | subjected.

  The second cooling water circuit 91 includes a water cooling condenser 28, a water cooling intercooler 126, a sub radiator 92 (second condenser), and a cooling water pump 93, and cooling water passages 95 to 97 through which the cooling water circulates through the respective constituent elements. Connect with.

  Since the fourth embodiment is merely a supercharger instead of the turbocharger of the first embodiment, the same operational effects as the first embodiment can be obtained.

  In the embodiment, the case where the liquid flowing through the second cooling water circuits 91 and 91 ′ is cooling water has been described, but the present invention is not limited to this. Any cooling liquid equivalent to cooling water may be used.

  In the embodiment, the refrigerant pump 22 and the expander 27 are coaxially connected, and the refrigerant pump 22 is driven by the output (power) of the expander 27 and the power is supplied to the output shaft of the engine 2 via the transmission device. Although described in the case (power regeneration), it is not limited to this case. For example, the present invention is also applied to a case where a refrigerant pump, an expander, and a motor generator are coaxially connected and driven, and the refrigerant pump and motor generator are driven by the output (power) of the expander and the power is recovered as electric power (power regeneration). Applicable.

2 Engine 21 Rankine cycle 22 Refrigerant pump 25 Expander clutch 26 Evaporator 27 Expander 28 Water-cooled condenser 61 Engine controller 81 Turbocharger (supercharger)
85 Water-cooled intercooler 91, 91 ′ Second cooling water circuit 92 Sub-radiator (second heat exchanger)
93 Cooling water pump 95-97 Cooling water passage (cooling fluid passage)
121 Supercharger (supercharger)
126 Water-cooled intercooler

Claims (6)

A heat exchanger that recovers engine waste heat into a refrigerant via engine cooling water, an expander that generates power using the refrigerant at the outlet of the heat exchanger, a condenser that condenses the refrigerant that has left the expander, A Rankine cycle including a refrigerant pump for supplying refrigerant from the condenser to the heat exchanger;
A supercharger for supercharging intake air, and an intercooler for cooling the intake air supercharged by the supercharger,
The condenser is a liquid-cooled condenser that condenses the refrigerant exiting the expander by heat exchange with a coolant,
The intercooler is a liquid cooling intercooler that cools the intake air by heat exchange with the cooling liquid,
The engine cooling water, the liquid cooling condenser, the liquid cooling intercooler, a second heat exchanger that cools the cooling liquid, and a pump that discharges the cooling liquid exiting the second heat exchanger. Is a waste heat utilization device for an engine, which is connected by a coolant passage forming an independent circuit . The liquid-cooled intercooler and the liquid-cooled condenser are provided in series,
2. The engine waste heat utilization apparatus according to claim 1, wherein the coolant at the outlet of the second heat exchanger flows in the order of a liquid cooling intercooler and a liquid cooling condenser from upstream. A clutch that connects and disconnects the transmission of rotational force from the expander to the engine;
3. The engine waste heat utilization apparatus according to claim 2, wherein the refrigerant pump is stopped when an intake air temperature at the liquid-cooled intercooler inlet becomes higher than a refrigerant temperature at the liquid-cooled condenser inlet.   The engine waste heat utilization apparatus according to claim 3, wherein supercharging by the supercharger is stopped when the clutch is fixed so that the clutch is always connected. The liquid-cooled intercooler and the liquid-cooled condenser are provided in parallel,
2. The engine waste heat utilization apparatus according to claim 1, wherein a coolant at an outlet of the second heat exchanger is allowed to flow through these. A clutch that connects and disconnects the transmission of rotational force from the expander to the engine;
An on-off valve that opens and closes a coolant passage that flows to the liquid-cooled condenser,
6. The engine waste heat utilization apparatus according to claim 5, wherein the on-off valve is closed when the clutch is fixed so that the clutch is always connected.