JP2015232273A - Rankine cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Rankine cycle capable of stably extracting power even at a time of starting an engine in a cold state.SOLUTION: A Rankine cycle (31) comprises: coolant passages (13, 14) cooling an engine with coolant; an evaporator (36); an expansion unit (37); a condenser (38); and a pump (32), the Rankine cycle (31) comprising: coolant temperature detection means (74) detecting a temperature of the coolant; and activation permission determination means (71) determining whether to permit activation of the Rankine cycle (31) by whether the temperature of the coolant reaches an activation permissible temperature, the activation permission determination means (71) setting the activation permissible temperature at a time of starting the engine in the cold state different from the activation permissible temperature at a time of restarting the engine in an engine warm-up completion state, and the activation permissible temperature at the time of starting the engine in the cold state being set higher than the activation permissible temperature at the time of restarting the engine in the engine warm-up completion state.

Description

  The present invention relates to a Rankine cycle, and more particularly to a method for starting a Rankine cycle when starting an engine in a cold state.

  Some control the temperature of the refrigerant and the temperature of the medium so that the temperature difference between the Rankine cycle medium and the refrigerant of the refrigeration cycle is equal to or greater than a predetermined value (see Patent Document 1).

JP 2009-204204 A

  By the way, in order to stably extract power from the Rankine cycle, it is necessary that the cooling water of the engine be equal to or higher than a predetermined temperature. When the cooling water temperature is lowered, the power that can be extracted from the Rankine cycle is reduced. Patent Document 1 proposes that the temperature difference between the Rankine cycle medium and the refrigerant in the refrigeration cycle be controlled to a predetermined value or more. However, the cooling water temperature is not necessarily stable, and the improvement There was room.

  Therefore, an object of the present invention is to provide a Rankine cycle that can stably extract power even when the engine is started in a cold state.

  The Rankine cycle of the present invention includes a cooling water passage that cools the engine with cooling water, an evaporator that exchanges heat with the cooling water to heat the working medium, and expands the working medium that has passed through the evaporator to generate power. A Rankine cycle having an expander that generates, a condenser that cools the working medium that has passed through the expander, and a pump that sends the working medium that has passed through the condenser to the evaporator, and detects the temperature of the cooling water Cooling water temperature detecting means, and activation permission determining means for determining whether or not to allow the Rankine cycle to be activated depending on whether or not the cooling water temperature has reached the activation permission temperature. In the Rankine cycle according to the present invention, the start permission determining means further makes the start permission temperature different between when the engine is started in a cold state and when the engine is restarted when the engine is warmed up. The start permission temperature at the engine start in the state is set higher than the start permission temperature at the engine restart in the engine warm-up completion state.

  When starting the engine in a cold state where the cooling water temperature is unstable, by setting the start-up permission water temperature of the Rankine cycle higher than when restarting the engine in the engine warm-up completion state where the cooling water temperature is stable, It is possible to stably extract power from the Rankine cycle, and at the time of engine restart when the engine is warmed up, the Rankine cycle can be quickly started, so the operating range of the Rankine cycle can be expanded. .

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 the schematic which shows the function of a refrigerant | coolant type | system | group valve | bulb. It is a schematic block diagram of a hybrid vehicle. It is a schematic perspective view of an engine. It is the schematic which looked at arrangement | positioning of an exhaust pipe from the downward direction of the vehicle. It is a characteristic view of a Rankine cycle operation area. It is a characteristic view of a Rankine cycle operation area. 6 is a timing chart showing a state when acceleration of the hybrid vehicle 1 is performed while assisting rotation of an engine output shaft by an expander torque. It is the timing chart which showed the mode of restart from the stop of Rankine cycle operation. It is a timing chart which shows the change of the cooling water temperature at the time of engine cold start of a 1st embodiment. It is a flow chart for explaining starting of a Rankine cycle of a 1st embodiment. It is a characteristic view of the outside air temperature correction coefficient of the first embodiment. It is a schematic block diagram showing the whole system of Rankine cycle of a 2nd embodiment. It is a timing chart which shows the change of the cooling water temperature at the time of engine cold start of a 2nd embodiment. It is a flow chart for explaining starting of a Rankine cycle of a 2nd embodiment. It is a flowchart for demonstrating restart of the Rankine cycle of 3rd Embodiment. It is a characteristic view for the basic hysteresis of the third embodiment. It is a characteristic view of the outside air temperature correction coefficient of the third embodiment. It is a flowchart for demonstrating restart of the Rankine cycle of 4th Embodiment. It is a characteristic view for the basic hysteresis of the fourth embodiment. It is a characteristic view of the outside air temperature correction coefficient of the fourth embodiment. It is a flow chart for explaining starting of a Rankine cycle of a 5th embodiment. It is a characteristic view of the outside air temperature correction coefficient of the fifth embodiment. It is a flow chart for explaining starting of a Rankine cycle of a 6th embodiment. It is a flowchart for demonstrating restart of the Rankine cycle of 7th Embodiment. It is a characteristic figure of the basic delay time of a 7th embodiment. It is a characteristic view of the outside temperature correction coefficient of 7th Embodiment. It is a schematic structure figure showing the whole system of a Rankine cycle of an 8th embodiment. It is a schematic block diagram showing the whole system of Rankine cycle of a 9th embodiment. It is a schematic structure figure showing the whole system of a Rankine cycle of a 10th embodiment. It is a schematic structure figure showing the whole system of a Rankine cycle of an 11th 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. The Rankine cycle 31 in FIG. 1 is configured to share the refrigeration cycle 51 and the refrigerant and the condenser 38, and a cycle in which the Rankine cycle 31 and the refrigeration cycle 51 are integrated is hereinafter expressed as an integrated cycle 30. FIG. 4 is a schematic configuration diagram of the hybrid vehicle 1 on which the integrated cycle 30 is mounted. The integrated cycle 30 includes a circuit (passage) through which the refrigerant of the Rankine cycle 31 and the refrigeration cycle 51 circulates and components such as a pump, an expander, and a condenser provided in the middle of the circuit, and a circuit for cooling water and exhaust. It shall refer to the entire system including (passage).

  In the hybrid vehicle 1, the engine 2, the motor generator 81, and the automatic transmission 82 are connected in series, and the output of the automatic transmission 82 is transmitted to the drive wheels 85 via the propeller shaft 83 and the differential gear 84. A first drive shaft clutch 86 is provided between the engine 2 and the motor generator 81. One of the frictional engagement elements of the automatic transmission 82 is configured as a second drive shaft clutch 87. The first drive shaft clutch 86 and the second drive shaft clutch 87 are connected to the engine controller 71, and their connection / disconnection (connected state) is controlled according to the driving conditions of the hybrid vehicle. In the hybrid vehicle 1, as shown in FIG. 7B, when the vehicle speed is in the EV traveling region where the efficiency of the engine 2 is poor, the engine 2 is stopped, the first drive shaft clutch 86 is disconnected, and the second drive shaft clutch 87 is connected. Thus, the hybrid vehicle 1 is caused to travel only by the driving force of the motor generator 81. On the other hand, when the vehicle speed deviates from the EV travel region and shifts to the Rankine cycle operation region, the engine 2 is operated to operate the Rankine cycle 31 (described later). 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 collective portion of the exhaust manifold 4. The exhaust pipe 5 branches off from the bypass exhaust pipe 6 on the way, and the exhaust pipe 5 in the section bypassed by the bypass exhaust pipe 6 has a waste heat recovery unit for exchanging heat between the exhaust and the cooling water. 22. As shown in FIG. 6, the waste heat recovery unit 22 and the bypass exhaust pipe 6 are disposed between the underfloor catalyst 88 and the sub muffler 89 downstream thereof as a waste heat recovery unit 23 in which these are integrated.

  First, the engine coolant circuit will be described with reference to FIG. 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, and on the cooling water passage 13 side when the cooling water temperature is low. The amount of cooling water passing through the radiator 11 is relatively reduced by reducing the valve opening. 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 However, the thermostat valve 15 is configured so that the flow does not stop completely. A bypass cooling water passage 14 that bypasses the radiator 11 is branched from the cooling water passage 13 and directly connected to a heat exchanger 36, which will be described later, and from the cooling water passage 13 to recover waste heat. The second bypass cooling water passage 25 connected to the heat exchanger 36 after passing through the vessel 22.

  The bypass cooling water passage 14 includes a heat exchanger 36 that exchanges heat with the refrigerant of the Rankine cycle 31. This heat exchanger 36 is an integrated heater and superheater. That is, two cooling water passages 36a and 36b are arranged in a row in the heat exchanger 36, and a refrigerant passage 36c through which the refrigerant of the Rankine cycle 31 flows so that heat can be exchanged between the refrigerant and the cooling water is a cooling water passage 36a, It is provided adjacent to 36b. Further, the passages 36a, 36b, and 36c are configured so that the refrigerant and the cooling water of the Rankine cycle 31 are in opposite directions when viewed from the whole heat exchanger 36.

  Specifically, one cooling water passage 36 a located on the upstream side (left side in FIG. 1) for the refrigerant of Rankine cycle 31 is interposed in the first bypass cooling water passage 24. The left side portion of the heat exchanger composed of the cooling water passage 36a and the refrigerant passage portion adjacent to the cooling water passage 36a flows through the refrigerant passage 36c by directly introducing the cooling water from the engine 2 into the cooling water passage 36a. It is a heater for heating the refrigerant of Rankine cycle 31.

  Cooling water that has passed through the waste heat recovery device 22 is introduced into the other cooling water passage 36b located on the downstream (right side in FIG. 1) side of the refrigerant in the Rankine cycle 31 via the second bypass cooling water passage 25. The right side portion of the heat exchanger (downstream side for the refrigerant of Rankine cycle 31) composed of the cooling water passage 36b and the refrigerant passage portion adjacent to the cooling water passage 36b is a cooling water obtained by further heating the cooling water at the outlet of the engine 2 by exhaust gas. Is a superheater that superheats the refrigerant flowing through the refrigerant passage 36c by introducing the refrigerant into the cooling water passage 36b.

  The cooling water passage 22 a of the waste heat recovery unit 22 is provided adjacent to the exhaust pipe 5. By introducing the cooling water at the outlet of the engine 2 into the cooling water passage 22a of the waste heat recovery unit 22, the cooling water can be heated to, for example, about 110 to 115 ° C. by high-temperature exhaust. The cooling water passage 22a is configured so that the exhaust and cooling water flow in opposite directions when the waste heat recovery device 22 is viewed from above.

  A control valve 26 is interposed in the second bypass cooling water passage 25 provided with the waste heat recovery unit 22. Cooling water temperature sensor at the outlet of the engine 2 so that the engine water temperature indicating the temperature of the cooling water inside the engine 2 does not exceed an allowable temperature (for example, 100 ° C.) for preventing deterioration of engine efficiency or knocking, for example. When the detected temperature 74 is equal to or higher than a predetermined value, the opening degree of the control valve 26 is decreased. When the engine water temperature approaches the permissible temperature, the amount of cooling water passing through the waste heat recovery device 22 is reduced, so that it is possible to reliably prevent the engine water temperature from exceeding the permissible temperature.

  On the other hand, if the flow rate of the second bypass cooling water passage 25 decreases, the cooling water temperature rising by the waste heat recovery device 22 rises too much and the cooling water evaporates (boils). In addition to a decrease in efficiency, the flow of cooling water in the cooling water passage may deteriorate and the temperature may rise excessively. In order to avoid this, the bypass exhaust pipe 6 that bypasses the waste heat recovery unit 22, and the thermostat valve 7 that controls the exhaust passage amount of the exhaust recovery unit 22 and the exhaust passage amount of the bypass exhaust pipe 6 are branched from the bypass exhaust pipe 6. Provided in the department. In other words, the thermostat valve 7 is configured such that the valve opening degree of the cooling water exiting the waste heat recovery unit 22 is such that the temperature of the cooling water exiting the waste heat recovery unit 22 does not exceed a predetermined temperature (for example, a boiling temperature of 120 ° C.). Adjusted based on temperature.

  The heat exchanger 36, the thermostat valve 7, and the waste heat recovery unit 22 are integrated as a waste heat recovery unit 23, and are arranged in the middle of the exhaust pipe under the floor at the approximate center in the vehicle width direction. The thermostat valve 7 may be a relatively simple temperature-sensitive valve using bimetal or the like, or may be a control valve controlled by a controller to which a temperature sensor output is input. Adjustment of the amount of heat exchange from the exhaust gas to the cooling water by the thermostat valve 7 involves a relatively large delay. Therefore, if the thermostat valve 7 is adjusted alone, it is difficult to prevent the engine water temperature from exceeding the allowable temperature. However, since the control valve 26 of the second bypass cooling water passage 25 is controlled based on the engine water temperature (exit temperature), the heat recovery amount can be quickly reduced and the engine water temperature can be surely exceeded the allowable temperature. Can be prevented. Further, if the engine water temperature has a margin before the allowable temperature, heat exchange is performed until the temperature of the cooling water exiting the waste heat recovery unit 22 becomes high enough to exceed the allowable temperature of the engine water temperature (for example, 110 to 115 ° C.). To increase the amount of recovered waste heat. The cooling water that has exited the cooling water passage 36 b is joined to the first bypass cooling water passage 24 via the second bypass cooling water passage 25.

  If the temperature of the cooling water from the bypass cooling water passage 14 toward the thermostat valve 15 is sufficiently lowered by exchanging heat with the refrigerant of the Rankine cycle 31 by the heat exchanger 36, for example, the cooling water passage 13 side of the thermostat valve 15 The amount of cooling water passing through the radiator 11 is relatively reduced. Conversely, when 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 31 not being operated, the valve opening of the thermostat valve 15 on the cooling water passage 13 side is increased. The amount of cooling water passing through the radiator 11 is relatively increased. Based on the operation of the thermostat valve 15, the cooling water temperature of the engine 2 is appropriately maintained, and heat is appropriately supplied (recovered) to the Rankine cycle 31.

  Next, Rankine cycle 31 will be described. Here, Rankine cycle 31 is not a simple Rankine cycle, but is configured as a part of integrated cycle 30 integrated with refrigeration cycle 51. Hereinafter, the basic Rankine cycle 31 will be described first, and then the refrigeration cycle 51 will be referred to.

  The Rankine cycle 31 is a system that recovers waste heat of the engine 2 to a refrigerant through cooling water of the engine 2 and regenerates the recovered waste heat as power. The Rankine cycle 31 includes a refrigerant pump 32, a heat exchanger 36 as a superheater, an expander 37, and a condenser (condenser) 38, and each component is connected by refrigerant passages 41 to 44 through which a refrigerant (R134a and the like) circulates. Has been.

  The shaft of the refrigerant pump 32 is connected to the output shaft of the expander 37 on the same shaft, and the refrigerant pump 32 is driven by the output (power) generated by the expander 37 and the generated power is used as the output shaft of the engine 2 ( (Refer to FIG. 2A). That is, the refrigerant pump 32 shaft and the output shaft of the expander 37 are arranged in parallel with the output shaft of the engine 2, and the belt 34 is hung between the pump pulley 33 provided at the tip of the refrigerant pump 32 shaft and the crank pulley 2a. Is turning (see FIG. 1). Note that a gear-type pump is employed as the refrigerant pump 32 of the present embodiment, and a scroll-type expander is employed as the expander 37 (see FIGS. 2B and 2C).

  In addition, an electromagnetic clutch (hereinafter referred to as “expander clutch”) 35 is provided between the pump pulley 33 and the refrigerant pump 32 so that the refrigerant pump 32 and the expander 37 can be connected to and disconnected from the engine 2. (See FIG. 2A). Therefore, the expander 37 is connected by connecting the expander clutch 35 when the output generated by the expander 37 exceeds the driving force of the refrigerant pump 32 and the friction of the rotating body (when the predicted expander torque is positive). Rotation of the engine output shaft can be assisted (assisted) by the output generated. 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 32 that circulates the refrigerant can also be covered by the recovered waste heat.

  The refrigerant from the refrigerant pump 32 is supplied to the heat exchanger 36 through the refrigerant passage 41. The heat exchanger 36 is a heat exchanger that causes heat exchange between the coolant of the engine 2 and the refrigerant, vaporizes the refrigerant, and superheats the refrigerant.

  The refrigerant from the heat exchanger 36 is supplied to the expander 37 through the refrigerant passage 42. The expander 37 is a steam turbine that converts heat into rotational energy by expanding the vaporized and superheated refrigerant. The power recovered by the expander 37 drives the refrigerant pump 32 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 37 is supplied to the condenser 38 via the refrigerant passage 43. The condenser 38 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 condenser 38 is arranged in parallel with the radiator 11 and is cooled by the radiator fan 12.

  The refrigerant liquefied by the condenser 38 is returned to the refrigerant pump 32 via the refrigerant passage 44. The refrigerant returned to the refrigerant pump 32 is sent again to the heat exchanger 36 by the refrigerant pump 32 and circulates through each component of the Rankine cycle 31.

  Next, the refrigeration cycle 51 will be described. Since the refrigerating cycle 51 shares the refrigerant circulating through the Rankine cycle 31, it is integrated with the Rankine cycle 31, and the configuration of the refrigerating cycle 51 itself is simplified. That is, the refrigeration cycle 51 includes a compressor (compressor) 52, a condenser 38, and an evaporator (evaporator) 55.

  The compressor 52 is a fluid machine that compresses the refrigerant of the refrigeration cycle 51 to a high temperature and a high pressure, and is driven by the engine 2. That is, as shown in FIG. 4, the compressor pulley 53 is fixed to the drive shaft of the compressor 52, and the belt 34 is wound around the compressor pulley 53 and the crank pulley 2a. The driving force of the engine 2 is transmitted to the compressor pulley 53 via the belt 34, and the compressor 52 is driven. An electromagnetic clutch (hereinafter referred to as “compressor clutch”) 54 is provided between the compressor pulley 53 and the compressor 52 so that the compressor 52 and the compressor pulley 53 can be connected and disconnected.

  Returning to FIG. 1, the refrigerant from the compressor 52 joins the refrigerant passage 43 via the refrigerant passage 56 and is then supplied to the condenser 38. The condenser 38 is a heat exchanger that condenses and liquefies the refrigerant by heat exchange with the outside air. The liquid refrigerant from the condenser 38 is supplied to an evaporator (evaporator) 55 through a refrigerant passage 57 branched from the refrigerant passage 44. The evaporator 55 is disposed in the case of the air conditioner unit in the same manner as a heater core (not shown). The evaporator 55 is a heat exchanger that evaporates the liquid refrigerant from the condenser 38 and cools the conditioned air from the blower fan by the latent heat of evaporation at that time.

  The refrigerant evaporated by the evaporator 55 is returned to the compressor 52 through the refrigerant passage 58. Note that the mixing ratio of the conditioned air cooled by the evaporator 55 and the conditioned air heated by the heater core is adjusted to a temperature set by the occupant according to the opening of the air mix door.

  In the integrated cycle 30 including the Rankine cycle 31 and the refrigeration cycle 51, various valves are appropriately provided 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 31, the refrigerant passage 44 that connects the pump upstream valve 61, the heat exchanger 36, and the expander 37 to the refrigerant passage 44 that connects the refrigeration cycle branch point 45 and the refrigerant pump 32. 42 is provided with an expander upstream valve 62. The refrigerant passage 41 that connects the refrigerant pump 32 and the heat exchanger 36 is provided with a check valve 63 to prevent the refrigerant from flowing backward from the heat exchanger 36 to the refrigerant pump 32. The refrigerant passage 43 that connects the expander 37 and the refrigeration cycle merge point 46 is also provided with a check valve 64 to prevent the refrigerant from flowing back from the refrigeration cycle merge point 46 to the expander 37. Further, an expander bypass passage 65 that bypasses the expander 37 from the upstream of the expander upstream valve 62 and merges upstream of the check valve 64 is provided, and a bypass valve 66 is provided in the expander bypass passage 65. Further, a pressure regulating valve 68 is provided in a passage 67 that bypasses the bypass valve 66. Also on the refrigeration cycle 51 side, an air conditioner circuit valve 69 is provided in the refrigerant passage 57 that connects the refrigeration cycle branch point 45 and the evaporator 55.

  The four valves 61, 62, 66, and 69 are all electromagnetic on-off valves. An expander upstream pressure signal detected by the pressure sensor 72, a refrigerant pressure Pd signal at the outlet of the condenser 38 detected by the pressure sensor 73, a rotation speed signal of the expander 37, and the like are input to the engine controller 71. . The engine controller 71 controls the compressor 52 of the refrigeration cycle 51 and the radiator fan 12 based on these input signals in accordance with predetermined operating conditions, and also controls the four electromagnetic on-off valves 61, 62, 66. , 69 is controlled.

  For example, the expander torque (regenerative power) is predicted based on the expander upstream pressure detected by the pressure sensor 72 and the expander rotational speed, and when the predicted expander torque is positive (assist rotation of the engine output shaft). The expander clutch 35 is engaged, and when the predicted expander torque is zero or negative, the expander clutch 35 is released. 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 35 can be appropriately engaged / released (refer to Japanese Unexamined Patent Application Publication No. 2010-190185 for details).

  The four on-off valves 61, 62, 66, 69 and the two check valves 63, 64 are refrigerant valves. The functions of these refrigerant valves are shown again in FIG.

  In FIG. 3, the pump upstream valve 61 is closed under a predetermined condition that the refrigerant is more easily biased to the circuit of the Rankine cycle 31 than the circuit of the refrigeration cycle 51, so that the refrigerant (including the lubricating component) of the Rankine cycle 31 is closed. In order to prevent the bias, as described later, the circuit of the Rankine cycle 31 is closed in cooperation with the check valve 64 downstream of the expander 37. The expander upstream valve 62 blocks the refrigerant passage 42 when the refrigerant pressure from the heat exchanger 36 is relatively low so that the refrigerant from the heat exchanger 36 can be held until the pressure becomes high. is there. Thereby, even when the expander torque cannot be sufficiently obtained, the heating of the refrigerant is promoted, and for example, the time until the Rankine cycle 31 is restarted (regeneration can actually be performed) can be shortened. The bypass valve 66 is opened so that the refrigerant pump 32 can be operated after the expander 37 is bypassed when the amount of refrigerant existing on the Rankine cycle 31 side is insufficient when the Rankine cycle 31 is started. This is for shortening the startup time of the Rankine cycle 31. By operating the refrigerant pump 32 after the expander 37 is bypassed, the refrigerant temperature at the outlet of the condenser 38 or the inlet of the refrigerant pump 32 has a predetermined temperature difference (subcool degree SC) from the boiling point considering the pressure at that portion. ) If the state lowered as described above is realized, the Rankine cycle 31 is ready to supply a sufficient liquid refrigerant.

  The check valve 63 upstream of the heat exchanger 36 is for maintaining the refrigerant supplied to the expander 37 at a high pressure in cooperation with the bypass valve 66, the pressure adjusting valve 68, and the expander upstream valve 62. Under conditions where the regeneration efficiency of the Rankine cycle 31 is low, the operation of the Rankine cycle 31 is stopped and the circuit is closed over the front and rear sections of the heat exchanger 36 to increase the refrigerant pressure during the stop, It is used so that Rankine cycle 31 can be restarted promptly. The pressure regulating valve 68 functions as a relief valve that opens when the pressure of the refrigerant supplied to the expander 37 becomes too high and releases the refrigerant that has become too high.

  The check valve 64 downstream of the expander 37 is for preventing the bias of the refrigerant to the Rankine cycle 31 in cooperation with the above-described pump upstream valve 61. If the engine 2 is not warmed immediately after the start of the operation of the hybrid vehicle 1, the Rankine cycle 31 becomes cooler than the refrigeration cycle 51, and the refrigerant may be biased toward the Rankine cycle 31 side. Although the probability of being biased toward the Rankine cycle 31 is not so high, for example, immediately after the start of vehicle operation in summer, the cooling capacity is most demanded in the situation where it is desired to cool the interior quickly, so the slight uneven distribution of refrigerant is also eliminated. Therefore, there is a demand for securing the refrigerant for the refrigeration cycle 51. Therefore, a check valve 64 is provided to prevent uneven distribution of refrigerant to the Rankine cycle 31 side.

  The compressor 52 does not have a structure in which the refrigerant can freely pass when driving is stopped, but can prevent the refrigerant from being biased to the refrigeration cycle 51 in cooperation with the air conditioner circuit valve 69. This will be described. When the operation of the refrigeration cycle 51 stops, the refrigerant may move from the relatively high temperature Rankine cycle 31 side to the refrigeration cycle 51 side during steady operation, and the refrigerant circulating through the Rankine cycle 31 may be insufficient. In the refrigeration cycle 51, the temperature of the evaporator 55 is low immediately after the cooling is stopped, and the refrigerant tends to accumulate in the evaporator 55 having a relatively large volume and a low temperature. In this case, the movement of the refrigerant from the condenser 38 to the evaporator 55 is interrupted by stopping the driving of the compressor 52, and the air conditioner circuit valve 69 is closed to prevent the refrigerant from being biased to the refrigeration cycle 51.

  Next, FIG. 5 is a schematic perspective view of the engine 2 showing a package of the entire engine 2. 5 is characterized in that the heat exchanger 36 is arranged vertically above the exhaust manifold 4. By placing the heat exchanger 36 in the space vertically above the exhaust manifold 4, the mountability of the Rankine cycle 31 to the engine 2 is improved. The engine 2 is provided with a tension pulley 8.

  Next, a basic operation method of the Rankine cycle 31 will be described with reference to FIGS. 7A and 7B.

  First, FIGS. 7A and 7B are operation region diagrams of the Rankine cycle 31. FIG. FIG. 7A shows the operating range of Rankine cycle 31 when the horizontal axis is the outside air temperature and the vertical axis is the engine water temperature (cooling water temperature). In FIG. 7B, the horizontal axis is the engine speed and the vertical axis is the engine torque (engine The operating range of the Rankine cycle 31 is shown.

  7A and 7B, the Rankine cycle 31 is operated when a predetermined condition is satisfied, and the Rankine cycle 31 is operated when both of these conditions are satisfied. In FIG. 7A, the operation of the Rankine cycle 31 is stopped in a region on the low water temperature side where priority is given to warm-up of the engine 2 and a region on the high outside air temperature side where the load on the compressor 52 increases. During warm-up when the exhaust temperature is low and the recovery efficiency is poor, the Rankine cycle 31 is not operated, so that the coolant temperature is quickly raised. The Rankine cycle 31 is stopped at a high outside air temperature where high cooling capacity is required, and sufficient refrigerant and cooling capacity of the condenser 38 are provided to the refrigeration cycle 51. In FIG. 7B, since the vehicle is a hybrid vehicle, the operation of the Rankine cycle 31 is stopped in the EV traveling region and the region on the high rotational speed side where the friction of the expander 37 increases. Since it is difficult to make the expander 37 have a high-efficiency structure with little friction at all rotation speeds, in the case of FIG. 7B, the expansion is performed so that the friction is small and the efficiency is high in the engine rotation speed range where the operation frequency is high. The machine 37 is configured (the dimensions of each part of the expander 37 are set).

  FIG. 8 is a timing chart showing a model when the hybrid vehicle 1 is accelerated while assisting the rotation of the engine output shaft by the expander torque. Note that, on the right side of FIG. 8, a state in which the operating state of the expander 37 changes at this time is shown on the expander torque map. Of the range delimited by the contour lines of the expander torque map, the portion where the expander rotation speed is low and the expander upstream pressure is high (upper left) has the largest expander torque, the expander rotation speed is high, and the expander upstream pressure is low. The expander torque tends to be smaller as it goes (lower right). In particular, the shaded area represents a region where the expander torque becomes negative on the premise of driving the refrigerant pump and becomes a load on the engine.

  Until t1 when the driver steps on the accelerator pedal, constant speed running is continued and the expander 37 generates a positive torque, and rotation assist of the engine output shaft is performed by the expander torque.

  After t1, the rotation speed of the expander 37, that is, the rotation speed of the refrigerant pump 32 increases in proportion to the engine rotation speed, but the increase in the exhaust gas temperature or the cooling water temperature has a delay with respect to the increase in the engine rotation speed. . Therefore, the ratio of the recoverable heat amount to the refrigerant amount increased by the increase in the rotational speed of the refrigerant pump 32 is reduced.

  Accordingly, as the expander rotational speed increases, the refrigerant pressure upstream of the expander decreases and the expander torque decreases.

  When the expander torque is not sufficiently obtained due to the decrease in the expander torque (for example, at the timing t2 when the expander torque is close to zero), the expander upstream valve 62 is switched from the open state to the closed state, thereby deteriorating the regeneration efficiency ( A phenomenon in which the expander 37 is dragged to the engine 2 conversely with an excessive decrease in the expander torque is avoided.

  After the expander upstream valve 62 is switched from the open state to the closed state, the expander clutch 35 is switched from connection (engaged) to disconnection (release) at the timing t3. By slightly delaying the disconnection timing of the expander clutch 35 from the timing when the expander upstream valve 62 is switched from the open state to the closed state, the refrigerant pressure upstream of the expander is sufficiently reduced, and the expander clutch 35 is disconnected. It is possible to prevent the expander 37 from rotating excessively. Further, a large amount of refrigerant is supplied into the heat exchanger 36 by the refrigerant pump 32, and the refrigerant is effectively heated even when the Rankine cycle 31 is stopped, so that the operation of the Rankine cycle 31 can be smoothly resumed. Yes.

  After t3, the expander upstream pressure rises again due to the increase in the heat radiation amount of the engine 2, and at the timing t4, the expander upstream valve 62 is switched from the closed state to the open state, so that the refrigerant is supplied to the expander 37. Resumed. Further, the expander clutch 35 is connected again at t4. By reconnecting the expander clutch 35, rotation assist of the engine output shaft by the expander torque is resumed.

  FIG. 9 shows how Rankine cycle 31 is restarted in a manner different from that in FIG. 8 (control of t4) from the stop of Rankine cycle operation in a state where expander upstream valve 62 is closed and expander clutch 35 is disconnected. It is the timing chart shown with the model.

  When the driver depresses the accelerator pedal at the timing of t11, the accelerator opening increases. At t11, the operation of the Rankine cycle 31 is stopped. For this reason, the expander torque is maintained at zero.

  As the engine rotation speed increases from t11, the heat dissipation amount of the engine 2 increases. Due to the increase in the heat dissipation amount, the temperature of the coolant flowing into the heat exchanger 36 increases, and the temperature of the refrigerant in the heat exchanger 36 increases. To rise. Since the expander upstream valve 62 is closed, the refrigerant pressure upstream of the expander upstream valve 62, that is, the expander upstream pressure, rises due to the increase in the refrigerant temperature by the heat exchanger 36 (t11 to t12).

  Switching from the Rankine cycle non-operating range to the Rankine cycle operating range is performed by the change in the operating state. When the expander clutch 35 is switched from the disconnected state to the connected state and the expander 37 is connected to the engine output shaft when the expander upstream valve 62 is not provided and the operation shifts to the Rankine cycle operation region, the expander 37 is connected. Becomes a load on the engine 2 and causes a torque shock.

  On the other hand, in FIG. 9, when switching to the Rankine cycle operation region, the expander upstream valve 62 is not immediately switched from the closed state to the open state. That is, the expander upstream valve 62 remains closed even after the transition to the Rankine cycle operation region.

  Eventually, it is determined that the expander 37 can be operated (driven) at a timing t12 when the differential pressure between the expander upstream pressure and the expander downstream pressure becomes greater than or equal to a predetermined pressure, and the expansion valve upstream valve 62 is changed from the closed state. Switch to the open state. By switching the expansion valve upstream valve 62 to the open state, a predetermined pressure of refrigerant is supplied to the expander 37, and the rotation speed of the expander rapidly increases from zero.

  At the timing t13 when the expander rotation speed reaches the engine rotation speed due to the increase in the expander rotation speed, the expander clutch 35 is switched from the disconnected state to the connected state. If the expander clutch 35 is connected before the expander 37 sufficiently increases the rotational speed, the expander 37 becomes an engine load and torque shock may occur. On the other hand, when the expander clutch 35 is delayed and connected at t13 when the rotational speed difference from the engine output shaft disappears, the expander 37 becomes an engine load. Torque shock can also be prevented.

  Next, FIG. 10 shows a change in the coolant temperature Tw of the engine when the engine is started in the cold state (hereinafter also referred to as “cold start”). The cooling water temperature Tw here is the temperature of the engine outlet.

  In FIG. 10, the case of an engine not having the Rankine cycle 31 (this engine is referred to as “conventional engine”) is indicated by a long broken line. In the conventional engine, the thermostat valve 15 is opened when the coolant temperature Tw reaches the valve opening temperature T0 (for example, about 80 ° C.) of the thermostat valve 15. For this reason, the cooling water temperature Tw swings up and down around the valve opening temperature T0.

  Explaining this, when the thermostat valve 15 opens at the timing of t1, the cooling water cooled by the radiator 11 flows into the engine 2, so that the cooling water temperature Tw that has risen until then decreases at a timing delayed from t1. Turn. When the descending cooling water temperature Tw falls below the valve opening temperature T0 of the thermostat valve 15 at the timing t2, the thermostat valve 15 is closed. Then, since the cooling water cooled by the radiator 11 does not flow into the engine, the cooling water temperature Tw that has been lowered so far exceeds the valve opening temperature T0 at a timing t3 delayed from t2. Then, the thermostat valve 15 opens at the timing of t3, and the cooling water cooled by the radiator 11 flows into the engine 2. Therefore, the cooling water temperature Tw that has risen until then turns downward at a timing delayed from t3. After that, the above is repeated. In this way, in the conventional engine, the cooling water temperature Tw fluctuates around the valve opening temperature T0 of the thermostat valve 15 at the cold start, and the average temperature is substantially the valve opening temperature T0 of the thermostat valve 15.

  Here, in an electromagnetic clutch as an expander clutch, an electromagnetic force is generated by energizing a 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 disconnected by stopping energization of the solenoid coil and eliminating the electromagnetic force. At this time, if the solenoid coil is energized to bring the electromagnetic clutch into the connected state, the driving force of the engine is transmitted to the refrigerant pump 32 via the belt-type transmission device, and the refrigerant pump 32 is driven from the non-driven state. Switch to state. As a result, the refrigerant pump 32 supplies the refrigerant to the heat exchanger 36, and the Rankine cycle 31 is activated. That is, the Rankine cycle 31 can be started by switching the refrigerant pump 32 from the non-driving state to the driving state.

  Now, in order to stably extract power from the Rankine cycle 31, it is necessary that the cooling water of the engine be equal to or higher than a predetermined temperature. When the cooling water temperature Tw entering the heat exchanger 36 is lowered, the Rankine cycle 31 The power that can be taken out will decrease. However, in the conventional apparatus, it has been proposed to control the temperature difference between the Rankine cycle medium and the refrigerant in the refrigeration cycle to a predetermined value or more. However, the cooling water temperature is not always stable, and the improvement is There was room.

  Therefore, the present inventor examined at what timing the Rankine cycle 31 should be started at the cold start. In the upper part of FIG. 10, the case of the reference example is indicated by a short broken line, and the case of the present embodiment is indicated by a solid line. Here, the reference example is a case where the Rankine cycle 31 is started at the timing t1 when the coolant temperature Tw reaches the valve opening temperature T0 of the thermostat valve 15. In the case of the reference example, as shown by a short broken line, the cooling water temperature is greatly reduced without increasing from the timing t1 when the Rankine cycle is started. This is because when the Rankine cycle 31 is started, the refrigerant in the Rankine cycle 31 is at a cold state temperature before starting the engine. For this reason, in the heat exchanger 36, the heat of the cooling water is abruptly taken away by the cold refrigerant when the Rankine cycle 31 is started, and the cooling water temperature Tw exiting the heat exchanger 36 is higher than the valve opening temperature T0. This is because it becomes lower. As described above, when the cooling water temperature Tw is lower than T0, power cannot be stably extracted from the Rankine cycle 31. Further, if the coolant temperature Tw becomes lower than the valve opening temperature T0, not only will it take longer for the engine 2 to complete warming up, but the engine friction will increase and the fuel efficiency of the engine 2 will worsen than the conventional engine. .

  On the other hand, in the first embodiment of the present invention, when the Rankine cycle 31 is started at the cold start, the Rankine cycle start permission temperature is increased in anticipation that heat is carried from the coolant to the refrigerant of the Rankine cycle 31. That is, a value obtained by adding a hysteresis component to the opening temperature T0 of the thermostat valve 15 is set as the Rankine cycle start permission temperature at the cold start. And Rankine cycle 31 is started at the timing of t11 when cooling water temperature Tw reaches this Rankine cycle starting permission temperature. The hysteresis is determined so that the temperature at the timing t11 when the cooling water temperature first peaks reaches the Rankine cycle activation permission temperature. Here, it is set to 4 ° C., for example. At this time, Rankine cycle start permission temperature at the time of cold start is 84 ° C. Although the hysteresis is described here as 4 ° C., it is finally determined by conformance. In the first embodiment, since the Rankine cycle start permission temperature is set higher by 4 ° C. than the hysteresis at the time of cold start, the coolant temperature Tw at the time of Rankine cycle start increases by the hysteresis. As a result, the cooling water temperature Tw after the Rankine cycle is started decreases from the timing when it is increased by the hysteresis amount. As shown by the solid line in the upper part of FIG. 10, the drop in the coolant temperature Tw from the start of the Rankine cycle 31 can be suppressed from the case of the reference example, and a change in the coolant temperature equivalent to that of the conventional engine is obtained. As a result, the cooling water of the engine becomes a predetermined temperature or higher, so that power can be stably taken out from the Rankine cycle 31. Further, unlike the reference example, the cooling water temperature Tw does not drop significantly, so that the time until the engine 2 is completely warmed up is not prolonged, and the engine friction can be made equal to that of the conventional engine. The deterioration of the fuel consumption of the engine 2 can be suppressed.

  On the other hand, although not shown in the figure, consider the time of engine restart when the engine 2 is warmed up (hereinafter also referred to as “hot restart”). At the time of hot restart, even if the Rankine cycle 31 is started at the valve opening temperature t0 of the thermostat valve 15, the cooling water temperature Tw is stable. For this reason, it is not necessary to raise the Rankine cycle activation permission temperature beyond the valve opening temperature T0 of the thermostat 15 as in the cold start. Therefore, at the time of hot restart, the valve opening temperature T0 of the thermostat 15 is set as the Rankine cycle start permission temperature as it is.

  As described above, in this embodiment, the Rankine cycle start permission temperature is made different between the cold start time and the hot restart time. Then, the Rankine cycle start permission temperature at the cold start is set higher than the Rankine cycle start permission temperature at the hot restart.

  The lower part of FIG. 10 shows changes in the local temperature of the engine at the cold start. The engine local temperature here is the temperature of the engine component different from the engine coolant temperature, for example, the temperature of the crank metal. When the cooling water temperature decreases at the timing t1 as in the comparative example, the local temperature of the engine decreases accordingly. This means that immediately after the cooling water temperature Tw rises during a cold start, not all the components of the engine 2 reach the equilibrium temperature, and the sensitivity of changes in the cooling water temperature Tw is high.

  This control executed by the engine controller 71 will be described with reference to the flowchart of FIG. The flow in FIG. 11 is for starting the Rankine cycle 31, and is executed at regular intervals (for example, every 10 ms).

  In the present embodiment, the engine 2 including the Rankine cycle 31 illustrated in FIG. 1 is mounted on the hybrid vehicle. However, the engine 2 including the Rankine cycle 31 illustrated in FIG. It can also be applied to vehicles. Here, the engine 2 may be either a gasoline engine or a diesel engine. In order to distinguish a vehicle powered only by the engine 2 from a hybrid vehicle, it is hereinafter referred to as an “engine vehicle”. The flow of FIG. 11 is a flow when the engine 2 including the Rankine cycle 31 shown in FIG. 1 is applied to an engine vehicle.

  In step 1, the engine coolant temperature Tw [° C.] detected by the water temperature sensor 74 is compared with the valve opening temperature T0 [° C.] of the thermostat valve 15. The valve opening temperature T0 is a temperature at which the thermostat valve 15 opens, and is about 80 ° C., for example. In the present embodiment, the valve opening temperature T0 is also the Rankine cycle start permission temperature at the time of hot restart. The water temperature sensor 74 is provided at the engine outlet (see FIG. 1). When the engine coolant temperature Tw is equal to or lower than the valve opening temperature T0, the current process is terminated. It is assumed that the expander clutch 35 is in a disconnected state when the ignition key is switched from OFF to ON.

  If the engine coolant temperature Tw exceeds the valve opening temperature T0 in step 1 and it is a hot restart, it is necessary to proceed to step 11 and start the Rankine cycle 31. For this reason, the process proceeds to step 2 to see whether it is a hot restart time or a cold star time. Step 2 is a part for determining whether it is a hot restart time or a cold star time by checking whether or not the coolant temperature Tw has reached the valve opening temperature T0 during the trip. is there. Here, one trip refers to the period from the start of the engine 2 to run the vehicle in an engine vehicle until the operation of the engine 2 is stopped to stop the running of the vehicle. When the cooling water temperature Tw reaches the valve opening temperature T0 for the first time during the trip, it is determined that the cooling water temperature Tw has reached the valve opening temperature T0 at the cold start, and the process proceeds to Step 3.

  In step 3, it is checked whether Rankine cycle start permission temperature Tal1 has been calculated at the cold start. As described later in step 7, when the Rankine cycle activation permission temperature Tal1 is calculated at the cold start, the Tal1 calculated flag = 1. Here, it is determined that the Tal1 calculated flag = 0, that is, the Rankine cycle start permission temperature Tal1 has not been calculated at the cold start, and the process proceeds to step 4.

  In step 4, the outside air temperature correction coefficient Htair1 [unknown number] is calculated by searching a table having the contents shown in FIG. 12 from the outside air temperature Tair [° C.] detected by the outside air temperature sensor 75 (see FIG. 1). The value obtained by multiplying the outside air temperature correction coefficient Htail1 by the basic hysteresis value Hys0 [° C.] in step 5 is set as the target hysteresis value mHys1 [° C.], that is, mHys1 is calculated by the following equation.

mHys1 = Hys0 × Htail1 (1)
In step 6, a value obtained by adding the target hysteresis mHys1 to the valve opening temperature T0 [° C.] of the thermostat valve 15 is used as the Rankine cycle start permission temperature Tal1 [° C.] at the time of cold start, that is, calculation for calculating Tal1 by the following equation: To do.

Tal1 = T0 + mHys1 (2)
As the basic hysteresis amount Hys0 in the above equation (1) is larger, the Rankine cycle activation permission temperature Tal1 in the equation (2) is higher, and the cooling water temperature Tw accompanying the activation of the Rankine cycle 31 can be suppressed. On the other hand, when the basic hysteresis amount Hys0 in the above equation (1) is too large, the start timing of the Rankine cycle 31 is delayed, and the operating range of the Rankine cycle 31 is narrowed. Therefore, the Rankine cycle start permission temperature Hys0 should be set so that the start-up timing of the Rankine cycle 31 is not so delayed while suppressing the drop in the coolant temperature Tw. The value of Hys0 is a value that depends on the specifications of the engine 2 and Rankine cycle 31, and is set by conformance if the specifications of the engine 2 and Rankine cycle 31 are determined. The conforming value of Hys0 is a constant value, and is assumed to be about 4 ° C. here.

  As shown in FIG. 12, the outside air temperature correction coefficient Hair1 is 1.0 when the outside air temperature Tair is the outside air temperature Tair0 (for example, 20 ° C.) at the time of adaptation. When the outside air temperature Tair is higher than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair1 becomes smaller than 1.0, and the target hysteresis amount mHys1 becomes smaller than the basic hysteresis amount Hys0 from the above equation (1). As a result, the Rankine cycle activation permission temperature Tal1 is lower than that in the case of the outside air temperature Tair0 at the time of adaptation from the above equation (2). This is because when the actual outside air temperature is higher than the outside air temperature at the time of adaptation, the cooling water temperature Tw does not drop significantly when the Rankine cycle 31 is activated, so the Rankine cycle activation permission temperature Tal1 may be lower than that at the time of adaptation. Because.

  On the other hand, when the outside air temperature Tair is lower than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Htair1 becomes larger than 1.0, and the target hysteresis amount mHys1 becomes larger than the basic hysteresis amount Hys2 from the above equation (1). As a result, the Rankine cycle start permission temperature Tal1 is higher than that in the case of the outside air temperature Tair0 at the time of adaptation from the above equation (2). This is because when the actual outside air temperature is lower than the adapted outside air temperature, the cooling water temperature Tw drops when the Rankine cycle 31 is started. Therefore, the hysteresis amount is increased to increase the Rankine cycle starting permission temperature Tal1. This is because it needs to be high.

  Since Rankine cycle start permission temperature Tal1 at the time of cold start is now calculated, Tal1 calculated flag = 1 is set in step 7.

  In Step 8, the Rankine cycle 31 is deactivated by disengaging the expander clutch 35.

  From the Tal1 calculated flag = 1 in step 7, the next and subsequent steps proceed to step 9 from step 3 to compare the coolant temperature Tw with the Rankine cycle activation permission temperature Tal1. Since the coolant temperature Tw is initially lower than the Rankine cycle activation permission temperature Tal1 when the Rankine cycle activation permission temperature Tal1 is calculated, the process proceeds to Step 8 and the Rankine cycle 31 is not driven. While the cooling water temperature Tw is lower than the Rankine cycle activation permission temperature Tal1, the operation of Step 8 is repeated. Eventually, when the coolant temperature Tw becomes equal to or higher than the Rankine cycle activation permission temperature Tal1, the process proceeds from Step 9 to Step 10, and the Rankine cycle 31 is activated by switching the expander clutch 35 from the disconnected state to the connected state. That is, at the cold start, the Rankine cycle start permission temperature Tal1 is set higher than the valve opening temperature T0 of the thermostat valve 15 by the target hysteresis mHys1, and the Rankine cycle 31 is started.

  On the other hand, when the cooling water temperature Tw reaches the valve opening temperature T0 of the thermostat valve 15 in step 2 not for the first time during the trip but for the second time or later, it is determined that it is a hot restart time, and the process proceeds to step 11. The Rankine cycle 31 is started immediately by connecting the expander clutch 35. That is, at the time of hot restart, the Rankine cycle activation permission temperature is set to the valve opening temperature T0 of the thermostat valve 15, and the Rankine cycle 31 is activated.

  Here, the effect of this embodiment is demonstrated.

  In the present embodiment, the cooling water passages 13 and 14 that cool the engine with cooling water, the heat exchanger 36 (evaporator) that heats the coolant (working medium) by exchanging heat with the cooling water, and the heat exchanger 36 are provided. An expander 37 that generates power by expanding the refrigerant that has passed, a condenser 38 that cools the refrigerant that has passed through the expander 37, and a refrigerant pump 32 (pump that sends the refrigerant that has passed through the condenser 38 to the heat exchanger 38 ) In the Rankine cycle 31, the water temperature sensor 74 (cooling water temperature detecting means) for detecting the temperature of the cooling water, and whether or not the cooling water temperature has reached the Rankine cycle activation permission temperature Tal1 (activation permission temperature). An engine controller 71 (starting permission determining means) for determining whether or not to allow the start of the Rankine cycle 31 is provided. Allowable temperature Tal1 is differentiated between cold start (when the engine is started in the cold state) and hot restart (when the engine is restarted when the engine is warmed up), and the Rankine cycle start permission temperature at the cold start Is set higher than the Rankine cycle start permission temperature at the time of hot restart (see Steps 1 to 8, Steps 1 to 3, 9, 8, Steps 1 to 3, 9, and 10 in FIG. 11). Immediately after the coolant temperature Tw rises at the cold start, not all the components of the engine 2 reach the equilibrium temperature, and the sensitivity of the change in the coolant temperature Tw is high. If Rankine cycle 31 is started in such a state and heat is taken away from the cooling water, the change in cooling water temperature Tw is large, Rankine cycle 31 does not function sufficiently, and there is a concern that pump loss will increase. . According to the present embodiment, at the cold start when the cooling water temperature Tw is unstable, the Rankine cycle activation permission water temperature Tal1 is set higher than that at the time of the hot restart where the cooling water temperature Tw is stable. Power can be taken out stably.

  On the other hand, when the engine has been warmed up and all the components of the engine 2 have reached the equilibrium temperature, the structural components of the engine 2 serve as a heat source, and the sensitivity of changes in the coolant temperature Tw is reduced. If the engine 2 is restarted in such a state, the Rankine cycle 31 can be driven in an efficient state without the coolant temperature Tw changing significantly. According to the present embodiment, during the hot restart, the Rankine cycle 31 is quickly activated at a coolant temperature lower than the Rankine cycle activation permission temperature at the cold start, so the operating range of the Rankine cycle 31 is expanded. be able to.

  The lower the outside air temperature, the more heat is radiated from the engine surface and the like, and the difference between the local temperature of the engine and the cooling water temperature Tw increases, and the sensitivity of the change in the cooling water temperature increases accordingly. Correspondingly, according to the present embodiment, the Rankine cycle start permission temperature Tal1 (start permission temperature) at the cold start (when the engine is started in the cold state) is increased as the outside air temperature Tair is lower ( Steps 4, 5, 6 and FIG. 12 in FIG. 11) and power can be stably taken out from the Rankine cycle 31 even when the outside air temperature Tair is low.

(Second Embodiment)
FIG. 13 is a schematic configuration diagram showing the entire system of the Rankine cycle 31 of the second embodiment, which replaces FIG. 1 of the first embodiment. The same parts as those in FIG. 1 of the first embodiment are denoted by the same reference numerals.

  The first embodiment is intended for the case where the valve opening temperature T0 of the thermostat valve 15 is constant. That is, the thermostat valve 15 of the first embodiment flows the cooling water to the bypass cooling water passage 14 without flowing to the radiator 11 when the valve is closed, and flows the cooling water to the radiator 11 when the valve is opened. On the other hand, the second embodiment is directed to the case where an electric controlled thermostat valve 15 ′ is provided instead of the thermostat valve 15 of the first embodiment. The electrically controlled thermostat valve 15 ′ that receives a signal from the engine controller 71 does not flow cooling water to the radiator 11 in the closed state but flows to the bypass cooling water passage 14, and flows the cooling water to the radiator 11 in the opened state. This valve can arbitrarily change the valve opening temperature.

  Here, when the OFF signal is given from the engine controller 71 to the electrically controlled thermostat valve 15 ′, the valve opening temperature becomes the first temperature, and when the ON signal is given, the valve opening temperature is higher than the first temperature. It shall be 2 temperatures. Specifically, the first temperature is about 80 ° C. as in the first embodiment, and the second temperature is about 90 ° C., for example. Thus, since the valve opening temperature can be arbitrarily changed in the electrically controlled thermostat valve 15 ′, the valve opening temperature that can be changed is referred to as a “valve opening temperature target”. Since the configuration of the electric thermostat valve 15 'itself is known, it will not be described in detail. The electric control thermostat valve 15 'is not limited. There is an engine that does not have a thermostat valve and uses a solenoid valve instead of a thermostat. A solenoid valve may be used instead of such a thermostat.

  Now, the purpose of providing the electric control thermostat valve 15 'to relatively increase the valve opening temperature target is to operate the Rankine cycle 31 efficiently. That is, when the valve opening temperature target is increased from 80 ° C. to 90 ° C., engine friction and cooling loss can be reduced. In addition, if the Rankine cycle 31 is operated at this time, the amount of heat that can be recovered by the heat exchanger 36 increases by the amount that the valve opening temperature target is increased, and the refrigerant that exits the heat exchanger 36 becomes higher temperature and pressure, and the expander 37 Thus, the heat recovery efficiency can be improved.

  In the system of the second embodiment shown in FIG. 13, the following points are also different from the system of the first embodiment. As shown in FIG. 1, the system of the first embodiment guides not only the cooling water at the engine outlet but also the cooling water raised in temperature by the waste heat recovery unit 22 to the heat exchanger 36 so that the refrigerant of the Rankine cycle 31 is used. The temperature was increased. Moreover, it integrated with Rankine cycle 31 and the refrigerating cycle 51, and shared the condenser 38 in each cycle. On the other hand, the system of the second embodiment is provided with a heat exchanger 91 (evaporator) that guides only the cooling water at the engine outlet and raises the temperature of the refrigerant in the Rankine cycle 31 as shown in FIG. Further, the Rankine cycle 31 and the refrigeration cycle 51 are not integrated, and the refrigeration cycle 51 is also provided with a dedicated condenser 92.

  FIG. 14 is a timing chart showing a change in the coolant temperature Tw when the engine is cold started according to the second embodiment.

  In FIG. 14, when the valve opening temperature target of the electric control thermostat valve 15 ′ is 80 ° C. in a conventional engine including the electric control thermostat valve 15 ′, the change in the cooling water temperature Tw at the cold start is shown by a thin solid line. Become. On the other hand, when the valve opening temperature target is changed to 90 ° C. in the conventional engine including the electric control thermostat valve 15 ′, the change in the coolant temperature Tw at the cold start is shown by the bold solid line. That is, when the valve opening temperature target is 80 ° C., the cooling water temperature Tw is centered on 80 ° C., and when the valve opening temperature target is 90 ° C., the cooling water temperature Tw is swung up and down around 90 ° C.

  In the second embodiment, when the valve opening temperature target is increased to 90 ° C., a value obtained by adding a hysteresis component to the increased valve opening temperature target is set as the Rankine cycle activation permission temperature at the cold start. And the Rankine cycle 31 is started at the timing of t22 when the coolant temperature Tw reaches the Rankine cycle start permission temperature at the time of cold start. The Rankine cycle 31 is not started at the timing t21 when the coolant temperature Tw reaches 90 ° C., which is the target valve opening temperature.

  Further, when the valve opening temperature target is 80 ° C., it is the same as in the case of the conventional engine including the thermostat valve 15 of the first embodiment. That is, when the valve opening temperature target is 80 ° C., in the second embodiment, a value obtained by adding a hysteresis component to the valve opening temperature target 80 ° C. is set as the Rankine cycle activation permission temperature at the cold start. And the Rankine cycle 31 is started at the timing of t11 when the coolant temperature Tw reaches the Rankine cycle start permission temperature at the time of this cold start. The Rankine cycle 31 is not started at the timing t1 when the cooling water temperature Tw reaches the valve opening temperature target of 80 ° C.

    This control executed by the engine controller 71 will be described with reference to the flowchart of FIG. The flow in FIG. 15 is for starting the Rankine cycle 31 of the second embodiment, and is executed at regular time intervals (for example, every 10 ms). The same parts as those in FIG. 11 of the first embodiment are denoted by the same reference numerals.

  A description will be given mainly of portions different from the first embodiment. Steps 21 to 23 are portions for switching the valve opening temperature target T1 of the electric thermostat valve 15 '. In step 21, the signal to the electric thermostat valve 15 'is observed. When this signal is an ON signal, the routine proceeds to step 22 where 90 ° C. is set to the valve opening temperature target T1 [° C.]. On the other hand, when the signal is an OFF signal, the process proceeds from step 21 to step 23, where 80 ° C. is set to the valve opening temperature target T1 [° C.]. In the second embodiment, the valve opening temperature target T1 is the Rankine cycle activation permission temperature at the time of hot restart.

  In step 24, the engine coolant temperature Tw detected by the water temperature sensor 74 is compared with the valve opening temperature target T1. When the engine coolant temperature Tw is equal to or lower than the valve opening temperature target T1, the current process is terminated.

  If it is during hot restart when the engine coolant temperature Tw exceeds the valve opening temperature target T1 in step 24, it is necessary to proceed to step 11 and start the Rankine cycle 31. For this reason, the process proceeds to step 2 and subsequent steps to see whether it is hot restart time or cold star time. Step 2 is a part for determining whether it is a hot restart time or a cold star time by checking whether or not the coolant temperature Tw has reached the valve opening temperature target T1 during the trip. It is. When the cooling water temperature Tw has reached the valve opening temperature target T1 for the first time during the trip, it is determined that the cooling water temperature Tw has reached the valve opening temperature target T1 at the cold start. Proceed to 25.

  In step 25, the value obtained by adding the target hysteresis mHys1 to the valve opening temperature target T1 [° C.] is used as Rankine cycle start permission temperature Tal1 [° C.] at the cold start, that is, Tal1 is calculated by the following equation.

Tal1 = T1 + mHys1 (3)
From the equation (3), when the valve opening temperature target T1 is 80 ° C. at the cold start, the temperature higher than the 80 ° C. by the target hysteresis mHys1 becomes the Rankine cycle start permission temperature Tal1. When the valve opening temperature target T1 is changed to 90 ° C. at the cold start, the temperature higher than the 90 ° C. by the target hysteresis mHys1 becomes the Rankine cycle start permission temperature Tal1.

  Since the Rankine cycle activation permission temperature Tal1 at the cold start is calculated, the Tal1 calculated flag = 1 is set in Step 7 and the Rankine cycle 31 is deactivated by setting the expander clutch 35 in the disconnected state in Step 8. .

  From the Tal1 calculated flag = 1 in step 7, the next and subsequent steps proceed to step 9 from step 3 to compare the coolant temperature Tw with the Rankine cycle activation permission temperature Tal1. When the cooling water temperature Tw becomes equal to or higher than the Rankine cycle start permission temperature Tal1, the process proceeds to Step 10, and the Rankine cycle 31 is started by switching the expander clutch 35 from the disconnected state to the connected state.

  On the other hand, when the coolant temperature Tw has reached the valve opening temperature target T1 in step 2 not the first time during the trip but the second time or later, it is determined that it is a hot restart, and the procedure proceeds to step 11 to expand the expander By connecting the clutch 35, the Rankine cycle 31 is immediately started. That is, at the time of hot restart, the Rankine cycle activation permission temperature is set as the valve opening temperature target T1, and the Rankine cycle 31 is activated. Here, when the valve opening temperature target T1 is 80 ° C. at the time of hot restart, 80 ° C. becomes the Rankine cycle start permission temperature at the time of hot restart. When the valve opening temperature target T1 is 90 ° C. at the time of hot restart, 90 ° C. becomes the Rankine cycle start permission temperature at the time of hot restart.

  As described above, according to the second embodiment, the first cooling water passage (13) for supplying the cooling water heated by cooling the engine 2 to the radiator 11 and the cooling water from the radiator 11 for returning the cooling water to the engine 2 are provided. Two cooling water passages (13), a bypass cooling water passage (14) branched from the first cooling water passage (13), bypassing the radiator 11 and joining the second cooling water passage (13), and in a closed state Cooling water does not flow to the radiator 11 but flows to the bypass cooling water passage (14). When the valve is open, the cooling water flows to the radiator 11 and the valve opening temperature can be arbitrarily changed. And when the Rankine cycle 31 is started during a cold start (when the engine is started in a cold state), the valve opening temperature target T1 of the electric thermostat valve 15 ′ is 15 is set higher than when the Rankine cycle 31 is started at the time of engine restart (when the engine is restarted when the engine is warmed up) (Steps 21 to 24, 2 to 5, 25, 7, 8, Step 3, FIG. 15). 9 and 10), even if the thermostat valve 15 'is electrically controlled and the valve opening temperature target T1 of the electrically controlled thermostat valve 15' is changed, the cooling water temperature is changed from the Rankine cycle 31 at the cold start when the cooling water temperature is unstable. Power can be taken out stably, and at the time of a hot restart, the Rankine cycle 31 can be quickly activated to widen the operating range of the Rankine cycle 31.

  More specifically, in order to set the Rankine cycle start permission temperature Tal1 relatively high, it is desirable to set the temperature higher than the target temperature targeted by the engine cooling device. In that case, it is necessary to wait until the temperature of the engine cooling device such as the radiator 11 rises to a certain temperature. On the other hand, when the electronically controlled thermostat valve 15 ′ capable of arbitrarily changing the valve opening temperature is provided as in the second embodiment, the valve opening temperature target at the cold start is set as the valve opening temperature target at the hot restart. By setting it higher, the driving of the Rankine cycle 31 can be started before the flow rate passing through the radiator 11 is increased.

(Third embodiment)
The flow of FIG. 16 is for restarting the Rankine cycle 31 of the third embodiment, and is executed at regular time intervals (for example, every 10 ms).

  In the first embodiment, the engine including the Rankine cycle 31 shown in FIG. 1 is applied to an engine vehicle. On the other hand, the third embodiment is directed to the case where the engine including the Rankine cycle 31 shown in FIG. 1 is an engine vehicle, and the vehicle is a vehicle that performs idle stop.

  In a vehicle that performs idle stop, it is necessary to consider the Rankine cycle start permission temperature at the time of engine restart from the idle stop separately from the Rankine cycle start permission temperature at the time of the first cold start. “At the first cold start” means that when the vehicle is driven, the ignition switch is turned on from OFF and the starter is started to start the engine in the cold state. At this time, the engine is started for the first time. . Here, the Rankine cycle start permission temperature at the time of the first cold start is referred to as “first Rankine cycle start permission temperature”. This initial Rankine cycle activation permission temperature is a value obtained by adding a hysteresis component to the valve opening temperature T0 of the thermostat valve 15.

  When the operation of the Rankine cycle 31 is stopped during the idle stop, when the Rankine cycle 31 is started when the engine is restarted from the idle stop, the engine state is different from that at the cold start. Therefore, when the Rankine cycle 31 is started when the engine is restarted from the idle stop, the engine state at that time should be taken into consideration. That is, when the idle stop time immediately before restarting the engine is relatively short, the engine 2 is warmer than when the idle stop time immediately before restarting the engine is relatively long, that is, during hot restart. Close state. Even after the engine warm-up is completed, the fuel efficiency of the engine will hardly change even if the cooling water temperature is somewhat lowered. Therefore, there is no problem even if the Rankine cycle 31 is started immediately after the engine is restarted from the idle stop, which is close to the hot restart. For this reason, the Rankine cycle start permission temperature when the idle stop time is relatively short may be lower than when the idle stop time is relatively long. Therefore, in the third embodiment, at the time of engine restart from the idle stop (engine forced stop), the Rankine cycle 31 is restarted at a Rankine cycle start permission temperature lower than the initial Rankine cycle start permission temperature (T0 + hysteresis). . For example, the Rankine cycle 31 is restarted at the timing t8 when the coolant temperature reaches the Rankine cycle start permission temperature (= T0) at the time of hot restart when the engine is restarted from the idle stop. Shows the case. This is because the idle stop time immediately before the engine restart is short from t6 to t7, and can be regarded as being close to the time of hot restart.

  On the other hand, when the engine 2 is cooled and the idle stop time becomes so long that it does not change from the cold state, the Rankine cycle start permission temperature at the time of engine restart from the idle stop is the same as the Rankine cycle start permission temperature at the cold start. It will be good. Therefore, in the third embodiment, the Rankine cycle activation permission temperature at the time of engine restart from the idle stop is increased as the idle stop time (engine forced stop time) immediately before the engine is restarted is longer.

  This control executed by the engine controller 71 will be specifically described with reference to the flow of FIG. In FIG. 16, in step 31, it is determined whether or not the engine is restarting from an idle stop (abbreviated as “IS” in the figure). If it is not at the time of engine restart from the idle stop, the current process is terminated as it is.

  When the engine is restarted from the idle stop, the routine proceeds from step 31 to step 32, where it is determined whether or not the Rankine cycle restart permission temperature Tal2 has been calculated. As will be described later in step 37, when the Rankine cycle restart permission temperature Tal2 is calculated when the engine is restarted from the idle stop, the Tal2 calculated flag is set to 1. Here, it is determined that the Tal2 calculated flag = 0, that is, the Rankine cycle restart permission temperature Tal2 has not been calculated when the engine is restarted from the idle stop, and the process proceeds to step 33.

  Steps 33 to 36 are parts for calculating Rankine cycle restart permission temperature Tal2. First, in step 33, a basic hysteresis Hys2 [° C.] is calculated by searching a table having the contents shown in FIG. 17 from the idle stop time immediately before restarting the engine. As shown in FIG. 17, the basic hysteresis amount Hys2 is zero until the idle stop time reaches a predetermined value IS0. The predetermined value IS0 is an upper limit of the time during which the engine 2 can be regarded as being in a warm-up completion state. This is because the cooling water temperature Tw does not drop even if hysteresis is not given when starting the Rankine cycle 31 when the engine is restarted from the engine state that can be regarded as being in the engine warm-up completion state.

  As shown in FIG. 17, the basic hysteresis amount Hys2 gradually increases between the predetermined value IS0 and the predetermined value IS1, reaches 4 ° C. at the predetermined value IS1, and maintains 4 ° C. when the predetermined value IS1 is exceeded. Value. This is due to the following reason. That is, when the idle stop time is equal to or greater than the predetermined value IS1, it can be considered that the engine is in a cold state. When the Rankine cycle 31 is started when the engine is restarted from a state in which the engine can be regarded as being in a cold state, it is the same as when the Rankine cycle 31 is started during a cold start. This is to avoid this because the Rankine cycle 31 is started without giving hysteresis when the engine is restarted from a state that can be regarded as being in the cold state, because the cooling water temperature Tw falls.

  In FIG. 17, Hys2 is approximated to 4 ° C. with a first-order lag from predetermined value IS0 to predetermined value IS1, but it may be approximated by a straight line (see the broken line in FIG. 17).

  In step 34, the outside air temperature correction coefficient Htair2 [anonymous number] is calculated by searching a table having the contents shown in FIG. 18 from the outside air temperature Tair detected by the outside air temperature sensor 75. In step 35, the value obtained by multiplying the outside air temperature correction coefficient Htar2 by the basic hysteresis value Hys2 is set as the target hysteresis value mHys2 [° C.], that is, mHys2 is calculated by the following equation.

mHys2 = Hys2 × Htail2 (4)
In step 36, the value obtained by adding the target hysteresis amount mHys2 to the valve opening temperature T0 of the thermostat valve 15 is set as the Rankine cycle restart permission temperature Tal2 [° C.] at the time of engine restart from the idle stop, that is, Tal2 is calculated by the following equation. To do.

Tal2 = T0 + mHys2 (5)
As shown in FIG. 18, the outside air temperature correction coefficient Hair2 is 1.0 when the outside air temperature Tair is the outside air temperature Tair0 at the time of adaptation. When the outside air temperature Tair is higher than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair2 becomes smaller than 1.0, and the target hysteresis amount mHys2 becomes smaller than the basic hysteresis amount Hys2 from the above equation (4). As a result, the Rankine cycle restart permission temperature Tal2 is lower than that in the case of the outside air temperature Tair0 at the time of adaptation from the above equation (5). This is because when the actual outside air temperature is higher than the outside air temperature at the time of adaptation, the cooling water temperature Tw does not drop significantly when the Rankine cycle 31 is activated, so the Rankine cycle restart permission temperature Tal2 is lower than that at the time of adaptation. Because it is good.

  On the other hand, when the outside air temperature Tair is lower than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Htair2 becomes larger than 1.0, and the target hysteresis amount mHys2 becomes larger than the basic hysteresis amount Hys2 from the above equation (4). Accordingly, the Rankine cycle restart permitting temperature Tal2 is higher than that in the case of the outside air temperature Tair0 at the time of adaptation from the above equation (5). This is because when the actual outside air temperature is lower than the adapted outside air temperature, the cooling water temperature Tw drops when the Rankine cycle 31 is started. Therefore, the hysteresis is increased and the Rankine cycle restart permission temperature Tal2 is increased. This is because it is necessary to increase the height.

  Since the Rankine cycle restart permission temperature Tal2 at the time of engine restart from the idle stop is calculated, the Tal2 calculated flag is set to 1 in step 37.

  In step 38, the Rankine cycle 31 is deactivated by disengaging the expander clutch 35.

  Since the Tal2 calculated flag = 1 in step 37, the process proceeds from step 32 to step 39 from the next time, and the coolant temperature Tw and Rankine cycle restart permission temperature Tal2 are compared. Since the coolant temperature Tw is initially lower than the Rankine cycle restart permission temperature Tal2 when the Rankine cycle restart permission temperature Tal2 is calculated, the routine proceeds to step 38 and the Rankine cycle 31 is not driven. While the cooling water temperature Tw is lower than the Rankine cycle restart permission temperature Tal2, the operation of step 38 is repeated. Eventually, when the coolant temperature Tw becomes equal to or higher than the Rankine cycle restart permission temperature Tal2, the routine proceeds from Step 39 to Step 40, where the Rankine cycle 31 is restarted by switching the expander clutch 35 from the disconnected state to the connected state.

  When the engine is restarted in a state where the immediately preceding idle stop time is short and can be regarded as the engine warm-up completion state, it is close to a hot restart. In response, according to the third embodiment, the vehicle includes a vehicle (a vehicle that forcibly stops the engine) that performs an idle stop when a predetermined condition is satisfied in the idle state. When the engine is restarted, the Rankine cycle 31 is restarted at a Rankine cycle start permission temperature (start permission temperature) lower than the first Rankine cycle start permission temperature (start permission temperature when starting the engine in the first cold state). Therefore (see steps 31, 33, 35, 36 and FIG. 17 in FIG. 16), the operating range of the Rankine cycle 31 can be expanded.

  The longer the idle stop time, the colder the engine. That is, when the engine is restarted in a state where the immediately preceding idle stop time is long and can be regarded as a cold state, it is close to a cold start. In response, according to the third embodiment, the start permission temperature lower than the initial Rankine cycle start permission temperature (start permission temperature when starting the engine in the first cold state) is set to the idle stop time (engine forced stop). The longer the time is) (see steps 33, 35, 36, and FIG. 17 in FIG. 16), the power is stably supplied from the Rankine cycle 31 even when the engine is restarted from the idle stop after the idle stop is prolonged. It can be taken out.

(Fourth embodiment)
The flow of FIG. 19 is for restarting the Rankine cycle 31 of the fourth embodiment, and is executed at regular time intervals (for example, every 10 ms).

  The third embodiment is directed to the case where the engine including the Rankine cycle 31 shown in FIG. 1 is an engine vehicle, and the vehicle is a vehicle that performs idle stop. On the other hand, the fourth embodiment is directed to a hybrid vehicle in which the engine including the Rankine cycle 31 shown in FIG.

  Even in a hybrid vehicle, it is necessary to consider the Rankine cycle start permission temperature at the time of engine restart from EV traveling separately from the Rankine cycle start permission temperature at the time of the first cold start. “At the first cold start” means that when the vehicle is driven, the ignition switch is turned on from OFF and the starter is started to start the engine in the cold state. At this time, the engine is started for the first time. . Also in the fourth embodiment, the Rankine cycle activation permission temperature at the first cold start is referred to as “initial Rankine cycle activation permission temperature”. This initial Rankine cycle activation permission temperature is a value obtained by adding a hysteresis component to the valve opening temperature T0 of the thermostat valve 15. The above-mentioned “EV traveling” refers to traveling a vehicle with only a motor in a hybrid vehicle.

  In the hybrid vehicle, the engine 2 is stopped during EV travel, and the engine 2 is restarted only when necessary. Since the operation of the Rankine cycle 31 is stopped during the EV travel, when the Rankine cycle 31 is started during the engine restart from the EV travel, it can be considered the same as during the engine restart from the idle stop. That is, when the engine stop time until the engine is restarted is relatively short, the engine is warmer than when the engine stop time until the engine is restarted is relatively long, that is, hot restart. Close to time. Even after the engine warm-up is completed, the fuel efficiency of the engine will hardly change even if the cooling water temperature is somewhat lowered. Therefore, there is no problem even if the Rankine cycle 31 is started immediately after the engine is restarted from the engine stop state, which is close to the hot restart. For this reason, the Rankine cycle start permission temperature when the engine stop time until the engine is restarted is relatively short may be lower than when the engine stop time until the engine is restarted is relatively long. . Therefore, in the fourth embodiment, when the engine is restarted from EV traveling, the Rankine cycle 31 is restarted at a Rankine cycle start permission temperature lower than the initial Rankine cycle start permission temperature (T0 + hysteresis).

  On the other hand, when the engine stop time until the engine restarts so long as the engine cools and does not change from the cold state becomes long, the Rankine cycle start permission temperature at the time of engine restart after EV traveling is the Rankine cycle start permission temperature at the cold start. It may be the same as the cycle start permission temperature. Therefore, in the third embodiment, the Rankine cycle activation permission temperature at the time of engine restart from EV traveling is increased as the engine stop time (engine forced stop time) until the engine is restarted is longer.

  This control executed by the engine controller 71 will be specifically described with reference to the flowchart of FIG. In FIG. 19, in step 51, it is determined whether or not the engine is restarted from EV traveling. If it is not at the time of engine restart from EV running, the current process is terminated as it is.

  When the engine is restarted from EV travel, the routine proceeds from step 51 to step 52, where it is determined whether or not the Rankine cycle restart permission temperature Tal3 has been calculated. As will be described later in step 57, when the Rankine cycle restart permission temperature Tal3 is calculated when the engine is restarted from EV travel, the Tal3 calculated flag = 1. Here, Tal3 calculated flag = 0, that is, the Rankine cycle restart permission temperature Tal3 has not been calculated at the time of engine restart, and the routine proceeds to step 53.

  Steps 53 to 56 are parts for calculating Rankine cycle restart permission temperature Tal3. First, at step 53, a basic hysteresis amount Hys3 [° C.] is calculated by searching a table having the contents shown in FIG. 20 from the engine stop time immediately before the engine is restarted. As shown in FIG. 20, the basic hysteresis Hys3 is zero until the engine stop time until the predetermined value ES0 until immediately before the engine is restarted. The predetermined value IS0 is an upper limit of the time during which the engine 2 can be regarded as being in a warm-up completion state. This is because the cooling water temperature Tw does not drop even if hysteresis is not given when starting the Rankine cycle 31 when the engine is restarted from the engine state that can be regarded as being in the engine warm-up completion state.

  As shown in FIG. 20, the basic hysteresis amount Hys3 gradually increases from the predetermined value ES0 to the predetermined value ES1, reaches 4 ° C. at the predetermined value ES1, and maintains 4 ° C. when the value exceeds the predetermined value ES1. Value. This is due to the following reason. That is, when the engine stop time until immediately before restarting the engine is equal to or greater than the predetermined value ES1, it can be considered that the engine is in a cold state. When the Rankine cycle 31 is started when the engine is restarted from a state in which the engine can be regarded as being in a cold state, it is the same as when the Rankine cycle 31 is started during a cold start. This is to avoid this because the Rankine cycle 31 is started without giving hysteresis when the engine is restarted from a state that can be regarded as being in the cold state, because the cooling water temperature Tw falls.

  In FIG. 20, Hys3 is approximated to 4 ° C. with a first-order lag from predetermined value IS0 to predetermined value IS1, but it may be approximated by a straight line (see broken line).

  In step 54, the outside air temperature correction coefficient Htair3 [anonymous number] is calculated by searching a table having the contents shown in FIG. 21 from the outside air temperature Tair detected by the outside air temperature sensor 75. In step 55, the value obtained by multiplying the outside air temperature correction coefficient Htar3 by the basic hysteresis value Hys3 is set as the target hysteresis value mHys3 [° C.], that is, mHys3 is calculated by the following equation.

mHys3 = Hys3 × Htail3 (6)
In step 56, the value obtained by adding the target hysteresis amount mHys3 to the valve opening temperature T0 of the thermostat valve 15 is set as the Rankine cycle restart permission temperature Tal3 [° C.] at the time of engine restart from EV traveling, that is, Tal3 is calculated by the following equation. To do.

Tal3 = T0 + mHys3 (7)
As shown in FIG. 21, the outside air temperature correction coefficient Htair3 is 1.0 when the outside air temperature Tair is the outside air temperature Tair0 at the time of adaptation. When the outside air temperature Tair is higher than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair3 becomes smaller than 1.0, and the target hysteresis amount mHys3 becomes smaller than the basic hysteresis amount Hys3 from the above equation (6). As a result, the Rankine cycle restart permitting temperature Tal3 is lower than that when the outside air temperature Tair0 at the time of adaptation is lower than the above equation (7). This is because when the actual outside air temperature is higher than the outside air temperature at the time of adaptation, the cooling water temperature Tw does not drop significantly when the Rankine cycle 31 is activated, so the Rankine cycle restart permission temperature Tal2 is lower than that at the time of adaptation. Because it is good.

  On the other hand, when the outside air temperature Tair is lower than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Htair3 becomes larger than 1.0, and the target hysteresis amount mHys3 becomes larger than the basic hysteresis amount Hys3 from the above equation (6). As a result, the Rankine cycle restart permission temperature Tal3 is higher than that when the outside air temperature Tair0 at the time of adaptation is higher than the above equation (7). This is because when the actual outside air temperature is lower than the adapted outside air temperature, the cooling water temperature Tw drops when the Rankine cycle 31 is started. Therefore, the hysteresis amount is increased and the Rankine cycle restart permission temperature Tal3 is increased. This is because it is necessary to increase the height.

  Since the Rankine cycle restart permission temperature Tal3 at the time of engine restart is calculated, the Tal3 calculated flag is set to 1 in step 57.

  In step 58, the Rankine cycle 31 is deactivated by disengaging the expander clutch 35.

  Since the Tal3 calculated flag = 1 in step 57, the process proceeds from step 52 to step 59 from the next time, and the coolant temperature Tw and Rankine cycle restart permission temperature Tal3 are compared. Since the coolant temperature Tw is initially lower than the Rankine cycle restart permission temperature Tal3 when the Rankine cycle restart permission temperature Tal3 is calculated, the process proceeds to step 58 and the Rankine cycle 31 is not driven. While the cooling water temperature Tw is lower than the Rankine cycle restart permission temperature Tal3, the operation of step 58 is repeated. Eventually, when the coolant temperature Tw becomes equal to or higher than the Rankine cycle restart permission temperature Tal3, the routine proceeds from Step 59 to Step 60, where the Rankine cycle 31 is restarted by switching the expander clutch 35 from the disconnected state to the connected state.

  When the engine is restarted in a state in which the engine stop time just before is short and the engine warm-up can be regarded as being completed, it is close to the hot restart. In response, according to the fourth embodiment, a hybrid vehicle is provided that forcibly stops the engine when a predetermined condition is satisfied. When the engine is restarted from EV travel (forced engine stop), the initial Rankine is provided. Since the Rankine cycle 31 is restarted at a Rankine cycle start permission temperature (start permission temperature) lower than the cycle start permission temperature (start permission temperature when starting the engine in the first cold state) (steps 51 and 53 in FIG. 19). 55, 56, see FIG. 20), the operating range of Rankine cycle 31 can be expanded.

  The longer the engine forced stop time, the colder the engine. That is, when the engine is restarted in a state in which the engine stop time just before is long and can be regarded as a cold state, it is close to the cold start. In response to this, according to the fourth embodiment, the start permission temperature lower than the initial Rankine cycle start permission temperature (start permission temperature when starting the engine in the first cold state) is set to the engine stop time (engine forced stop). The longer the time is, the higher the time is (see steps 53, 55, 56, and FIG. 20 in FIG. 19), so that power can be stably extracted from the Rankine cycle 31 even when the engine is restarted after the EV travel has been prolonged. .

(Fifth and sixth embodiments)
The flow in FIGS. 22 and 24 is for starting the Rankine cycle 31 of the fifth and sixth embodiments, and is executed at regular intervals (for example, every 10 ms). The flow of FIG. 22 replaces FIG. 11 of 1st Embodiment, and the flow of FIG. 24 replaces FIG. 15 of 2nd Embodiment. The same parts as those in FIGS. 11 and 15 of the first and second embodiments are denoted by the same reference numerals.

  In the first and second embodiments, a value obtained by adding a hysteresis component to the valve opening temperature T0 and the valve opening temperature target T1 is used as the Rankine cycle activation permission temperature at the cold start, and the cooling water temperature is equal to the Rankine cycle activation permission temperature. The Rankine cycle 31 was started at the arrival timing. This is because the Rankine cycle 31 is started at the timing when the cooling water temperature Tw further rises by a predetermined temperature width (hysteresis) from the timing when the cooling water temperature Tw reaches T0, T1 at the cold start. It is an idea to do. In other words, the Rankine cycle 31 may be started at a timing when a predetermined delay time has elapsed from the timing when the cooling water temperature Tw reaches T0, T1. Therefore, in the fifth and sixth embodiments, the Rankine cycle 31 is started at a timing when a predetermined delay time has elapsed from the timing when the coolant temperature Tw reaches T0 and T1 at the cold start. The basic delay times of the fifth and sixth embodiments are set corresponding to the basic hysteresis amount of the first and second embodiments. The timing for starting the Rankine cycle 31 is determined not by the start permission temperature but by the start permission time. Hereinafter, the fifth and sixth embodiments will be described together.

  The difference from the first and second embodiments will be mainly described. In FIG. 22 and FIG. 24, it is determined whether or not the cooling water temperature Tw has reached T0 and T1 during the trip in step 2 at the beginning. See. When the cooling water temperature Tw has reached T0, T1 for the first time during the trip, it is determined that the cooling water temperature Tw has reached T0, T1 at the cold start, and the routine proceeds to step 71.

  In step 71, it is checked whether or not the target delay time mΔtdly1 has been calculated at the cold start. As will be described later in step 75, when the target delay time mΔtdly1 is calculated at the cold start, the mΔtdly1 calculated flag = 1. Here, mΔtdly1 calculated flag = 0, that is, the target delay time mΔtdly1 has not been calculated at the time of engine start in the engine cold state, and the routine proceeds to step 72.

  In step 72, the outside air temperature correction coefficient Htair4 [anonymous number] is obtained by searching a table having the contents shown in FIG. 23 from the outside air temperature Tair [° C.] detected by the outside air temperature sensor 75 (see FIGS. 1 and 13). calculate. In step 73, a value obtained by multiplying the outside air temperature correction coefficient Htair4 by the basic delay time Δtdly0 [seconds] is set as a target delay time mΔtdly1 [seconds], that is, mΔtdly1 is calculated by the following equation.

mΔtdly1 = Δtdly0 × Htail4 (8)
The longer the basic delay time Δtdly0 in the above equation (8), the higher the Rankine cycle start temperature, and the lowering of the coolant temperature Tw accompanying the start of the Rankine cycle 31 can be suppressed. On the other hand, when the basic delay time Δtdly0 in the above equation (8) is too long, the start timing of the Rankine cycle 31 is delayed, and the operating range of the Rankine cycle 31 is narrowed. Therefore, the basic delay time Δtdly0 should be set so that the start-up timing of the Rankine cycle 31 is not so delayed while suppressing the drop in the coolant temperature Tw. The value of Δtdly0 is a value that depends on the specifications of the engine 2 and Rankine cycle 31, and is set by conformance if the specifications of the engine 2 and Rankine cycle 31 are determined. The adaptation value of Δtdly0 is a positive constant value. For example, when the outside air temperature is the outside air temperature at the time of adaptation, the cooling water temperature is further increased from the timing when the cooling water temperature becomes T0 and T1 to the first and second cooling water temperatures. It is a value corresponding to the time until the temperature rises by 4 ° C., which is the basic hysteresis amount of the embodiment.

  As shown in FIG. 23, the outside air temperature correction coefficient Hair4 is 1.0 when the outside air temperature Tair is the outside air temperature Tair0 at the time of adaptation. When the outside air temperature Tair is higher than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair4 becomes smaller than 1.0, and the target delay time mΔtdly1 becomes smaller than the basic delay time Δtdly0 from the above equation (8). As a result, the Rankine cycle activation permission timing becomes earlier than that when the outside air temperature Tair0 is met. This is because when the actual outside air temperature is higher than the outside air temperature at the time of adaptation, the cooling water temperature Tw does not drop when the Rankine cycle 31 is started, so that the Rankine cycle start permission timing may be earlier.

  On the other hand, when the outside air temperature Tair is lower than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair4 becomes larger than 1.0, and the target delay time mΔtdly1 becomes larger than the basic delay time Δtdly0 from the above equation (8). As a result, the Rankine cycle activation permission timing becomes later than the outside air temperature Tair0 at the time of adaptation. This is because when the actual outside air temperature is lower than the adapted outside air temperature, the cooling water temperature Tw drops when the Rankine cycle 31 is started. Therefore, the Rankine cycle starting permission timing is delayed and the Rankine cycle starting temperature is increased. This is because it is necessary to increase the height.

  Since the target delay time mΔtdly1 at the cold start is calculated, the timer is started at step 74 (timer value Δt1 = 0). The timer value Δt1 [seconds] is for measuring an elapsed time after the coolant temperature Tw reaches T0 and T1. In step 75, m.DELTA.tdly1 calculated flag = 1.

  In Step 8, the Rankine cycle 31 is deactivated by disengaging the expander clutch 35.

  Since the mΔtdly1 calculated flag = 1 in step 75, the process proceeds from step 71 to step 76 from the next time, and the timer value Δt1 is compared with the target delay time mΔtdly1. Since the timer value Δt1 is initially smaller than the target delay time mΔtdly1 when the target delay time mΔtdly1 is calculated, the process proceeds to step 75 and the Rankine cycle 31 is not driven. While the timer value Δt1 is smaller than the target delay time mΔtdly1, the operation of step 75 is repeated. Eventually, when the timer value Δt1 becomes equal to or greater than the target delay time mΔtdly1, the routine proceeds from step 76 to step 10, and the Rankine cycle 31 is started by switching the expander clutch 35 from the disconnected state to the connected state. That is, at the time of cold start, the Rankine cycle start permission timing is set as a timing that is delayed by the target delay time mΔtdly1 from the timing when the coolant temperature Tw reaches T0 and T1, and the Rankine cycle 31 is started.

  On the other hand, when the cooling water temperature Tw has reached T0, T1 in step 2 not the first time during the trip but the second time or later, it is determined that it is a hot restart time, and the process proceeds to step 11 to proceed to the expander clutch 35. The Rankine cycle 31 is started immediately by connecting. That is, at the time of hot restart, the Rankine cycle 31 is activated with the timing at which the coolant temperature Tw reaches T0 and T1 as the Rankine cycle activation permission timing.

  Here, the operational effects of the fifth and sixth embodiments will be described.

  In the fifth embodiment, the cooling water passages 13 and 14 that cool the engine with the cooling water, the heat exchanger 36 (evaporator) that exchanges heat with the cooling water and heats the refrigerant (working medium), and the heat exchanger 36. The expander 37 that expands the refrigerant that has passed through the generator 37 generates power, the condenser 38 that cools the refrigerant that has passed through the expander 37, and the refrigerant pump 32 that sends the refrigerant that has passed through the condenser 38 to the heat exchanger 38 ( In the Rankine cycle 31 having a pump), a water temperature sensor 74 (cooling water temperature detecting means) for detecting the temperature of the cooling water, and after the cooling water temperature reaches the valve opening temperature T0 (a constant temperature) of the thermostat valve 15. An engine controller 71 (startup permission determination means) that determines whether or not to allow the start of the Rankine cycle 31 based on whether or not the basic delay time Δtdly0 (predetermined time) has elapsed; The engine controller 71 makes the basic delay time Δtdly0 different between a cold start (when the engine is started in a cold state) and a hot restart (when the engine is restarted when the engine is warmed up). The basic delay time Δtdly0 is set longer than the basic delay time Δtdly0 at the time of hot restart (Steps 1, 2, 71 to 75, 8, Steps 1, 2, 71, 76, 8, Steps 1, 2 in FIG. 22). 71, 76, 10). That is, the basic delay time Δtdly0 at the cold start is a positive constant value. On the other hand, at the time of hot restart, the timing at which the coolant temperature Tw reaches T0, T1 is the Rankine cycle activation permission timing, so the basic delay time Δtdly0 at the time of hot restart is zero. Thus, the basic delay time Δtdly0 at the cold start is set longer than the basic delay time Δtdly0 at the hot restart. Since the fifth embodiment introduces the basic delay time Δtdly0 instead of the basic hysteresis component Hys0 of the first embodiment, the fifth embodiment also exhibits the same operational effects as the first embodiment. That is, at the cold start when the cooling water temperature is unstable, the basic delay time Δtdly0 is set longer than that at the hot restart when the cooling water temperature is stable, so that power can be stably taken out from the Rankine cycle 31. In addition, since the start of the Rankine cycle 31 is permitted promptly during hot restart, the operating range of the Rankine cycle 31 can be expanded.

  Moreover, according to 6th Embodiment, there exists an effect similar to 2nd Embodiment.

  According to the sixth embodiment, the start permission timing at the time of cold start (when the engine is started in the cold state) is delayed as the outside air temperature Tair is lower (see step 72 in FIG. 22, FIG. 23). Power can be stably taken out from the Rankine cycle 31 even when Tair is low.

(Seventh embodiment)
The flow of FIG. 25 is for restarting the Rankine cycle 31 of the seventh embodiment, and is executed at regular time intervals (for example, every 10 ms). The flow of FIG. 25 replaces the flow of FIG. 16 of the third embodiment. The same parts as those in FIG. 16 of the third embodiment are denoted by the same reference numerals.

  The third embodiment is directed to the case where the engine including the Rankine cycle 31 shown in FIG. 1 is an engine vehicle, and the vehicle is a vehicle that performs idle stop. On the other hand, the seventh embodiment is also intended for the case where the engine including the Rankine cycle 31 shown in FIG. 1 is an engine vehicle, and the vehicle is a vehicle that performs idle stop.

  In a vehicle that performs idle stop, it is necessary to consider the Rankine cycle activation permission timing at the time of engine restart from the idle stop separately from the Rankine cycle activation permission timing at the time of the first cold start. “At the first cold start” means that when the vehicle is driven, the ignition switch is turned on from OFF and the starter is started to start the engine in the cold state. At this time, the engine is started for the first time. As mentioned above. Here, the Rankine cycle activation permission timing at the first cold start is referred to as “initial Rankine cycle activation permission timing”. The initial Rankine cycle activation permission timing is a timing at which a predetermined delay time has elapsed from the timing at which the coolant temperature Tw reaches the valve opening temperature T0 of the thermostat valve 15.

  In the third embodiment, the Rankine cycle 31 is restarted at a Rankine cycle start permission temperature lower than the initial Rankine cycle start permission temperature (T0 + hysteresis) when the engine is restarted from the idle stop. In the third embodiment, the Rankine cycle activation permission temperature at the time of engine restart from the idle stop is increased as the idle stop time immediately before the engine is restarted is longer. On the other hand, 7th Embodiment restarts Rankine cycle 31 at the Rankine cycle starting permission timing earlier than the initial Rankine cycle starting permission timing at the time of engine restart from idle stop. In the seventh embodiment, the Rankine cycle activation permission timing at the time of engine restart from the idle stop is increased as the idle stop time immediately before the engine is restarted is longer.

  This control executed by the engine controller 71 will be specifically described with reference to the flow of FIG. Here, the difference from the third embodiment will be mainly described. In FIG. 25, when the engine is restarted from the idle stop, the routine proceeds from step 31 to step 81, where it is determined whether or not the target delay time mΔtdly2 has been calculated. As will be described later in Step 86, when the target delay time mΔtdly2 is calculated when the engine is restarted from the idle stop, the mΔtdly2 calculated flag = 1. Here, mΔtdly2 calculated flag = 0, that is, the target delay time mΔtdly2 has not been calculated at the time of engine restart from the idle stop, and the routine proceeds to step 82.

  Steps 82 to 84 are parts for calculating the target delay time mΔtdly2. First, in step 82, a basic delay time Δtdly1 [second] is calculated by searching a table having the contents shown in FIG. 26 from the idle stop time immediately before restarting the engine. As shown in FIG. 26, the basic delay time Δtdly1 is zero until the idle stop time reaches a predetermined value IS0. The predetermined value IS0 is an upper limit of the time during which the engine 2 can be regarded as being in a warm-up completion state. This is because the coolant temperature Tw does not drop even if a delay time is not given when starting the Rankine cycle 31 when the engine is restarted from an engine state that can be regarded as being in the engine warm-up completion state.

  As shown in FIG. 26, the basic delay time Δtdly1 gradually increases from the predetermined value IS0 to the predetermined value IS1, reaches the predetermined value D [seconds] at the predetermined value IS1, and reaches a predetermined value IS1 or more. It is a value that maintains the value D. This is due to the following reason. That is, when the idle stop time is equal to or greater than the predetermined value IS1, it can be regarded as being in a cold state. When the Rankine cycle 31 is started when the engine is restarted from a state in which the engine can be regarded as being in a cold state, it is the same as when the Rankine cycle 31 is started during a cold start. This is to avoid this because the Rankine cycle 31 is started without giving a delay time when the engine is restarted from a state that can be regarded as being in the cold state, because the cooling water temperature Tw falls.

  In FIG. 26, Δtdly1 is approximated to the predetermined value D with a first order delay from the predetermined value IS0 to the predetermined value IS1, but it may be approximated by a straight line (see the broken line in FIG. 26).

  In step 83, an outside air temperature correction coefficient Htair5 [anonymous number] is calculated by searching a table having the contents shown in FIG. 27 from the outside air temperature Tair detected by the outside air temperature sensor 75. In step 84, the value obtained by multiplying the outside air temperature correction coefficient Htair5 by the basic delay time Δtdly1 is set as the target delay time mΔtdly2 [seconds], that is, mΔtdly2 is calculated by the following equation.

mΔtdly2 = Δtdly1 × Htail5 (9)
As shown in FIG. 27, the outside air temperature correction coefficient Hair5 is 1.0 when the outside air temperature Tair is the outside air temperature Tair0 at the time of adaptation. When the outside air temperature Tair is higher than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair5 becomes smaller than 1.0, and the target delay time mΔtdly2 becomes shorter than the basic delay time Δtdly1 from the above equation (9). This is because when the actual outside air temperature is higher than the outside air temperature at the time of adaptation, the cooling water temperature Tw does not drop when the Rankine cycle 31 is started, so the target delay time mΔtdly2 may be shorter than that at the time of adaptation. is there.

  On the other hand, when the outside air temperature Tair is lower than the adapted outside air temperature Tair0, the outside air temperature correction coefficient Hair5 becomes larger than 1.0, and the target delay time mΔtdly2 becomes longer than the basic delay time Δtdly1 from the above equation (9). This is because when the actual outside air temperature is lower than the adapted outside air temperature, the cooling water temperature Tw drops when the Rankine cycle 31 is started, so the target delay time is lengthened and the Rankine cycle start permission timing is set. This is because it is necessary to slow down.

  Since the target delay time mΔtdly2 at the time of engine restart from the idle stop is calculated, the timer is started in step 85 (timer value Δt2 = 0). The timer value Δt2 [seconds] is for measuring the elapsed time from the idle stop release timing. In step 86, m.DELTA.tdly2 calculated flag = 1.

  In step 38, the Rankine cycle 31 is deactivated by disengaging the expander clutch 35.

  Since the mΔtdly2 calculated flag = 1 in step 86, the process proceeds from step 81 to step 87 in the next time and compares the timer value Δt2 with the target delay time mΔtdly2. Since the timer value Δt2 is initially shorter than the target delay time mΔtdly2 when the target delay time mΔtdly2 is calculated, the routine proceeds to step 38 and the Rankine cycle 31 is not driven. While the timer value Δt2 is shorter than the target delay time mΔtdly2, the operation of step 38 is repeated. Eventually, when the timer value Δt2 becomes equal to or greater than the target delay time mΔtdly2, the routine proceeds from step 87 to step 40, where the Rankine cycle 31 is restarted by switching the expander clutch 35 from the disconnected state to the connected state.

  When the engine is restarted in a state where the immediately preceding idle stop time is short and can be regarded as the engine warm-up completion state, it is close to a hot restart. In response to this, according to the seventh embodiment, the vehicle includes a vehicle (a vehicle that forcibly stops the engine) that performs an idle stop when a predetermined condition is established in the idle state. When the engine is restarted, the Rankine cycle 31 is restarted at a Rankine cycle start permission timing (start permission timing) earlier than the first Rankine cycle start permission timing (start permission timing at the time of engine start in the first cold state). Therefore (see steps 31, 82, 84 and FIG. 26 in FIG. 25), the operating range of the Rankine cycle 31 can be expanded.

  The longer the idle stop time, the colder the engine. That is, when the engine is restarted in a state where the immediately preceding idle stop time is long and can be regarded as a cold state, it is close to a cold start. In response, according to the seventh embodiment, the start permission timing earlier than the initial Rankine cycle start permission timing (start permission timing at the time of starting the engine in the first cold state) is set to the idle stop time (engine forced stop). The longer the time is) (see step 82 of FIG. 25, FIG. 26), the power can be stably extracted from the Rankine cycle 31 even when the engine is restarted from the idle stop after the idle stop is prolonged. .

  In the seventh embodiment, the engine including the Rankine cycle 31 shown in FIG. 1 is an engine vehicle, and the vehicle is a vehicle that performs idle stop. The seventh embodiment can be applied as a target. In this case, the same operational effects as those of the fourth embodiment are obtained.

(Eighth and ninth embodiments)
28 and 29 are schematic configuration diagrams showing the entire system of the Rankine cycle 31 of the eighth and ninth embodiments, FIG. 28 is FIG. 1 of the first embodiment, and FIG. 29 is a diagram of the second embodiment. 13 is replaced. The same parts as those in FIGS. 1 and 13 of the first and second embodiments are denoted by the same reference numerals.

  The difference between the first and second embodiments is the difference in the opening temperature of the thermostat valve. That is, the first embodiment is that the opening temperature of the thermostat valve 15 is constant T0, and the opening temperature of the thermostat valve 15 ′ can be switched between 80 ° C. and 90 ° C. (variable) in the second embodiment. It was a form. On the other hand, the difference between the eighth and ninth embodiments is also the difference in the opening temperature of the thermostat valve. That is, the eighth embodiment is that the opening temperature of the thermostat valve 15 is constant T0, and the ninth embodiment is that the opening temperature of the thermostat valve 15 ′ can be switched between 80 ° C. and 90 ° C. (variable). It is a form.

  In the first and second embodiments, the refrigerant pump 32 is driven by the engine 2 by switching the expander clutch 35 from the disconnected state to the connected state, thereby starting the Rankine cycle 31. On the other hand, the eighth and ninth embodiments differ from the first and second embodiments in the starting method of the Rankine cycle 31. That is, in the eighth and ninth embodiments, the expander clutch 35 is not provided unlike the first and second embodiments. Instead, a bypass refrigerant passage 101 that bypasses the refrigerant pump 32 is provided, and an electromagnetic on-off valve 102 that opens and closes the bypass refrigerant passage 101 in response to a signal from the engine controller 71 is provided in the bypass refrigerant passage 101. ing. Here, it is assumed that the electromagnetic on-off valve 102 is in a fully opened state when an OFF signal is given from the engine controller 71 and is fully closed when an ON signal is given from the engine controller 71.

  In the Rankine cycle 31 system of the eighth and ninth embodiments, the engine 2 and the refrigerant pump 32 are always in a directly connected state via the belt transmission device. When the engine is started, the electromagnetic on-off valve 102 is fully open. For this reason, the refrigerant pump 32 is driven to discharge the refrigerant when the engine 2 is started, but the refrigerant from the refrigerant pump 32 mainly circulates in the refrigerant passage 41, the bypass refrigerant passage 101, and the refrigerant passage 44. (See arrows in FIGS. 28 and 29). Although the refrigerant from the refrigerant pump 32 may flow somewhat toward the heat exchanger 91, the amount is considered to be minute. That is, as long as the electromagnetic on-off valve 102 is fully opened, the Rankine cycle 31 is not operated.

  On the other hand, when the electromagnetic on-off valve 102 is switched from the fully open state to the fully closed state, the refrigerant circulation around the refrigerant passage 41, the bypass refrigerant passage 101, and the refrigerant passage 44 is interrupted, and the refrigerant from the refrigerant pump 32 is exchanged with the heat exchanger. It flows toward 91. That is, the Rankine cycle 31 is started by switching the electromagnetic on-off valve 102 from the fully open state to the fully closed state.

  Also in the system of the eighth embodiment configured as described above, the flow of FIG. 11 of the first embodiment and the flow of FIG. 22 of the fifth embodiment can be applied, respectively, and the same as the first and fifth embodiments. Has the effect of. Also in the system of the ninth embodiment, the flow of FIG. 15 of the second embodiment and the flow of FIG. 24 of the sixth embodiment can be applied, respectively, and the same operation as the first and sixth embodiments. There is an effect.

  However, in the flow of FIG. 11 and FIG. 22 as the eighth embodiment, the following points need to be changed according to the difference in the starting method of the Rankine cycle 31. That is, in Step 8 of FIGS. 11 and 22, the Rankine cycle 31 is set in a non-activated state by turning off the electromagnetic on-off valve 102. On the other hand, in steps 10 and 11 of FIGS. 11 and 22, the Rankine cycle 31 is started by switching the electromagnetic on-off valve 102 from the OFF state to the ON state.

  Moreover, in the flow of FIG. 15 and FIG. 24 as 9th Embodiment, it is necessary to change the following points according to the difference in the starting method of Rankine cycle 31. FIG. That is, in step 8 of FIGS. 15 and 24, the Rankine cycle 31 is set in a non-activated state by turning off the electromagnetic on-off valve 102. On the other hand, in steps 10 and 11 of FIGS. 15 and 24, the Rankine cycle 31 is started by switching the electromagnetic on-off valve 102 from the OFF state to the ON state.

  When the engine including the Rankine cycle 31 of the eighth and ninth embodiments is applied to a vehicle that is an engine vehicle and performs idle stop, the flow of FIG. 16 of the third embodiment and FIG. 25 of the seventh embodiment. This flow can be applied, and the same effect as the third and seventh embodiments can be obtained. Moreover, when applying the engine provided with Rankine cycle 31 of 8th, 9th embodiment to a hybrid vehicle, the flow of FIG. 19 of 4th Embodiment can be applied and the effect similar to 4th Embodiment. Play.

  However, in the flow of FIGS. 16, 25, and 19 as the eighth and ninth embodiments, the following points need to be changed according to the difference in the starting method of the Rankine cycle 31. That is, in Steps 38 and 58 of FIGS. 16, 25, and 19, the Rankine cycle 31 is set in a non-activated state by turning off the electromagnetic on-off valve 102. On the other hand, in Steps 40 and 60 of FIGS. 16, 25, and 19, the Rankine cycle 31 is restarted by switching the electromagnetic on-off valve 102 from the OFF state to the ON state.

(10th and 11th embodiments)
30 and 31 are schematic configuration diagrams showing the entire system of Rankine cycle 31 according to the tenth and eleventh embodiments. FIG. 30 is a diagram of FIG. 1 of the first embodiment, and FIG. 31 is a diagram of the second embodiment. 13 is replaced. The same parts as those in FIGS. 1 and 13 of the first and second embodiments are denoted by the same reference numerals.

  The difference between the tenth and eleventh embodiments is also the difference in the opening temperature of the thermostat valve. That is, the tenth embodiment is that the opening temperature of the thermostat valve 15 is constant T0, and the eleventh embodiment is that the opening temperature of the thermostat valve 15 ′ can be switched between 80 ° C. and 90 ° C. (variable). It is a form.

  The tenth and eleventh embodiments are also different from the first and second embodiments in the starting method of the Rankine cycle 31. That is, in the tenth and eleventh embodiments, unlike the first and second embodiments, the pump pulley 33, the belt 34, and the expander clutch 35 are not provided. Instead, the refrigerant pump 32, the motor generator 111, and the expander 37 are arranged on the same shaft, and the motor generator 111 and the battery 113 are connected via an inverter 112. The inverter 112 supplies electric power from the battery 113 to the motor generator 111 or takes out electric power generated by the motor generator 111 and stores it in the battery 113.

  In the Rankine cycle 31 system of the tenth and eleventh embodiments, the refrigerant pump 32 is in a stopped state when no signal is given from the engine controller 71 to the motor generator 111. That is, when no signal is given to the motor generator 111, the Rankine cycle 31 is in a non-operating state.

  On the other hand, when the motor generator 111 is operated as a motor by a signal from the engine controller 71, the refrigerant pump 32 is driven by the motor, and the refrigerant from the refrigerant pump 32 flows toward the heat exchanger 91. That is, Rankine cycle 31 is started by making motor generator 111 work as a motor.

  In addition, when the output generated by the expander 37 exceeds the driving force of the refrigerant pump 32 and the friction of the rotating body (when the predicted expander torque is positive), the motor generator 111 is caused to work as a generator, thereby expanding the expander 37. Can be recovered as electric power. Fuel efficiency can be improved by storing the collected power in a battery.

  Also in the system of the tenth embodiment configured as described above, the flow of FIG. 11 of the first embodiment and the flow of FIG. 22 of the fifth embodiment can be applied, respectively, as in the first and fifth embodiments. Has the effect of. In the system of the eleventh embodiment, the flow of FIG. 15 of the second embodiment and the flow of FIG. 24 of the sixth embodiment can be applied, respectively, and the same effects as the first and sixth embodiments. Play.

  However, in the flow of FIG. 11 and FIG. 22 as the tenth embodiment, the following points need to be changed according to the difference in the starting method of the Rankine cycle 31. That is, in Step 8 of FIGS. 11 and 22, the Rankine cycle 31 is set in a non-starting state by not outputting any signal to the motor generator 111. On the other hand, in steps 10 and 11 of FIGS. 11 and 22, the Rankine cycle 31 is started by operating the motor generator 111 as a motor.

  Moreover, in the flow of FIG. 15 and FIG. 24 as 11th Embodiment, it is necessary to change the following points according to the difference in the starting method of Rankine cycle 31. FIG. That is, in Step 8 of FIGS. 15 and 24, no signal is output to the motor generator 111, so that the Rankine cycle 31 is set in a non-activated state. On the other hand, in steps 10 and 11 of FIGS. 15 and 24, the Rankine cycle 31 is started by causing the motor generator 111 to act as a motor.

  When the engine including the Rankine cycle 31 of the tenth and eleventh embodiments is applied to an engine vehicle that performs idle stop, the flow of FIG. 16 of the third embodiment and FIG. 25 of the seventh embodiment. This flow can be applied, and the same effect as the third and seventh embodiments can be obtained. Further, when an engine including the Rankine cycle 31 of the tenth and eleventh embodiments is applied to a hybrid vehicle, the flow of FIG. 19 of the fourth embodiment can be applied, and the same effect as the fourth embodiment. Play.

  However, in the flows of FIGS. 16, 25, and 19 as the tenth and eleventh embodiments, the following points need to be changed according to the difference in the startup method of the Rankine cycle 31. That is, in Steps 38 and 58 of FIGS. 16, 25, and 19, no signal is output to the motor generator 111 so that the Rankine cycle 31 is in a non-activated state. On the other hand, in steps 40 and 50 of FIGS. 16, 25, and 19, the Rankine cycle 31 is restarted by causing the motor generator 111 to act as a motor.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Engine 13 Cooling water path (1st cooling water path, 2nd cooling water path)
14 Bypass cooling water passage 15 Thermostat valve 15 'Electric control thermostat valve (valve)
31 Rankine cycle 32 Refrigerant pump (pump)
35 expander clutch 36 heat exchanger (evaporator)
37 Expander 38 Condenser 51 Refrigeration cycle 52 Compressor 54 Compressor clutch 71 Engine controller (start-up permission judging means)
74 Water temperature sensor (cooling water temperature detection means)
91 Heat exchanger (evaporator)
92 Condenser 101 Bypass refrigerant passage 102 Electromagnetic on-off valve 111 Motor generator 112 Inverter

Claims (9)

A cooling water passage for cooling the engine with cooling water;
An evaporator that heats the working medium by exchanging heat with the cooling water;
An expander that generates power by expanding the working medium that has passed through the evaporator;
A condenser for cooling the working medium that has passed through the expander;
A Rankine cycle having a pump for pumping the working medium that has passed through the condenser to the evaporator,
Cooling water temperature detecting means for detecting the temperature of the cooling water;
Starting permission determination means for determining whether to permit starting of the Rankine cycle based on whether or not the cooling water temperature has reached the starting permission temperature,
The start permission determination means makes the start permission temperature different between when the engine is started in the cold state and when the engine is restarted when the engine is warmed up, and when the engine is started in the cold state. A Rankine cycle characterized in that the temperature is set to be higher than a start permission temperature at the time of restarting the engine in a state where the engine is warmed up. A first cooling water passage for supplying cooling water heated by cooling the engine to the radiator;
A second cooling water passage for returning cooling water from the radiator to the engine;
A bypass cooling water passage that branches off from the first cooling water passage and bypasses the radiator and joins the second cooling water passage;
In the valve closing state, the cooling water does not flow to the radiator but to the bypass cooling water passage, and in the valve opening state, the cooling water flows to the radiator and a valve capable of arbitrarily changing the valve opening temperature is provided in the cooling water passage. Prepared,
When starting the Rankine cycle when starting the engine in the cold state, the valve opening temperature target of the valve is set higher than when starting the Rankine cycle when restarting the engine when the engine is warmed up. The Rankine cycle according to claim 1, characterized in that: A vehicle that forcibly stops the engine when a predetermined condition is satisfied in an idle state or a vehicle that forcibly stops the engine when a predetermined condition is satisfied;
The Rankine cycle is restarted at a start permission temperature lower than a start permission temperature at the time of starting the engine in the cold state for the first time when the engine is restarted from the forced engine stop. Rankine cycle of 2.   4. The Rankine cycle according to claim 3, wherein a start permission temperature lower than a start permission temperature at the time of starting the engine in the first cold state is increased as the engine forced stop time is longer.   The Rankine cycle according to claim 1 or 2, wherein the start permission temperature at the start of the engine in the cold state is higher as the outside air temperature is lower. A cooling water passage for cooling the engine with cooling water;
An evaporator that heats the working medium by exchanging heat with the cooling water;
An expander that generates power by expanding the working medium that has passed through the evaporator;
A condenser for cooling the working medium that has passed through the expander;
A Rankine cycle having a pump for pumping the working medium that has passed through the condenser to the evaporator,
Cooling water temperature detecting means for detecting the temperature of the cooling water;
Starting permission determining means for determining whether or not to allow starting of the Rankine cycle based on whether or not a predetermined time has elapsed since the cooling water temperature reached a certain temperature,
The activation permission determining means makes the predetermined time different between when the engine is started in the cold state and when the engine is restarted when the engine is warmed up, and the predetermined time when the engine is started in the cold state. A Rankine cycle characterized in that it is set to be longer than a predetermined time when the engine is restarted in the machine complete state. A vehicle that forcibly stops the engine when a predetermined condition is satisfied in an idle state or a vehicle that forcibly stops the engine when a predetermined condition is satisfied;
The Rankine cycle is restarted at a start permission timing earlier than a start permission timing at the time of engine start in the cold state for the first time when the engine is restarted from the forced engine stop. The described Rankine cycle.   The Rankine cycle according to claim 6, wherein the start permission timing that is earlier than the start permission timing at the time of starting the engine in the first cold state is delayed as the engine forced stop time is longer.   The Rankine cycle according to claim 6, wherein the start permission timing at the time of starting the engine in the cold state is delayed as the outside air temperature is lower.

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