JP6497255B2 - Waste heat utilization system - Google Patents

Description

  The present invention relates to a waste heat utilization system.

  There is a device in which a heat exchanger is provided in a bypass passage branched from an exhaust pipe immediately downstream of the exhaust manifold, a heat insulation case is provided in a differential case at the rear of the vehicle, and a refrigerant is circulated between the heat exchanger and the heat insulation case. (See Patent Document 1). In this device, exhaust heat is recovered into a refrigerant by a heat exchanger, the refrigerant whose temperature has increased by this heat recovery is guided to a heat retaining case, and the temperature of the gear oil inside the differential case is increased, thereby warming up the differential gear. Promoting.

JP 2004-278345 A

  By the way, there is a demand for effective utilization of the thermal energy remaining in the exhaust on the downstream side even if the exhaust on the downstream side after activating the manifold catalyst and the main catalyst provided in the exhaust pipe. For example, heat is recovered from the exhaust after activating the downstream main catalyst, and a request for promoting warm-up of the differential gear and a heating request for the vehicle interior (hereinafter simply referred to as “indoor”) are performed using the recovered heat. Think of meeting both. In order to meet the above indoor heating requirements, the heater is configured to include a heater core and a blower fan, the refrigerant heated by the exhaust heat recovery device is guided to the heater core, and heat is exchanged with the inside air passing through the heater core. Is to do it. In this case, the heater core can be used as a radiator while acting as a heater. In other words, when the refrigerant becomes a high temperature in the high load region of the engine, the bypass passage and the exhaust switching valve of Patent Document 1 are not necessary if the high temperature refrigerant is cooled by the heater core as a radiator. The inventor has come up with the idea. However, there is no description in Patent Document 1 from the viewpoint of satisfying the above two requirements.

  Therefore, an object of the present invention is to provide a waste heat utilization system that can improve the reliability of a gear mechanism inside a differential case in a high load region without requiring a bypass passage and an exhaust switching valve.

The exhaust heat utilization system of the present invention includes an exhaust heat recovery device, a heat exchanger, a heater core, a blower fan, a refrigerant passage, a pump, and a control unit. The exhaust heat recovery unit is provided in an exhaust pipe in the vicinity of a differential case in which gear oil is sealed, and can exchange heat between the exhaust flowing through the exhaust pipe and the refrigerant. The heat exchanger is provided in the differential case and can exchange heat between the gear oil and the refrigerant. The heater core can exchange heat between air and the refrigerant. The blower fan allows air to pass through the heater core in one direction. The refrigerant passage connects the exhaust heat recovery unit, the heat exchanger, and the heater core. The pump circulates the refrigerant through the refrigerant passage. The control unit drives the pump and the blower fan when the temperature of the refrigerant is in a temperature range higher than a first predetermined value, and allows the outside air to pass through the heater core to generate heat from the refrigerant. A first mode is performed in which the air is exchanged and the outside air after the heat exchange is released to the outside of the room. An engine having the exhaust pipe is mounted in front of the vehicle, the exhaust pipe runs under the floor of the vehicle toward the rear of the vehicle, and is arranged so that a downstream end of the exhaust pipe opens to the rear of the vehicle. The differential case is disposed under the floor behind the vehicle, and the exhaust heat recovery device, the heat exchanger, and the heater core are provided when the output of the engine is transmitted to the rear wheels via a gear mechanism inside the differential case. Are arranged together at the rear of the vehicle.

  In the present invention, when the refrigerant reaches a high temperature in the high load region of the engine, the heater core can be used as a radiator to cool the refrigerant at a high temperature, so that a bypass passage and an exhaust switching valve are provided as in the conventional device. There is no need. Further, since the heat is radiated from the refrigerant by the heater core, it is possible to avoid the fear that the refrigerant will boil due to insufficient heat radiation. Further, when the vehicle is running in a high load region of the engine, the gear oil inside the differential case can become overheated when the differential gear rotates at a high rotational speed. At this time, the refrigerant whose temperature has been lowered by the heat radiation from the heater core is guided to the heat exchanger, whereby heat exchange is performed between the refrigerant whose temperature has been lowered and the gear oil inside the differential case. When the refrigerant temperature is lower than the superheated gear oil, the heat exchanger functions as an oil cooler, and the reliability of the differential gear in a high load range can be improved.

1 is a schematic configuration diagram of a vehicle on which an engine according to a first embodiment of the present invention is mounted. It is a schematic block diagram of a waste heat utilization apparatus. It is the table | surface which put together the control method of the waste heat utilization apparatus. It is a state diagram of the exhaust heat utilization apparatus in the control mode 1. It is a state diagram of the exhaust heat utilization apparatus in the control mode 2. It is a state diagram of the exhaust heat utilization apparatus in the control mode 3. It is a characteristic view of a water pump rotational speed. It is a characteristic view of a blower fan rotational speed. It is a flowchart for demonstrating the control method which a control apparatus performs. It is a flowchart for demonstrating the control method which a control apparatus performs.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of a vehicle 1 on which an engine 2 according to the first embodiment of the present invention is mounted, and FIG. 2 is a schematic configuration diagram of an exhaust heat utilization device 21 (exhaust heat utilization system).

  In FIG. 1, the vehicle 1 includes an engine 2 as a power source in front of the vehicle 1 (left side in FIG. 1). The engine is, for example, a gasoline engine. The vehicle 1 is a rear wheel drive vehicle. Under the floor of the vehicle 1, a transmission 3, a propeller shaft 4, a differential gear device 5, and a drive shaft 6 are arranged in this order toward the rear (right side in FIG. 1) of the vehicle 1. The differential gear device arranged at the rearmost of the vehicle is hereinafter simply referred to as “rear differential”. The output shaft of the engine 2 is transmitted to the rear wheels (drive wheels behind the vehicle) 7 through the transmission 3, the propeller shaft 4, the rear differential 5, and the drive shaft 6. The front wheels (driven wheels in front of the vehicle) 8 are rotatably provided on the steering mechanism 9.

  The engine 2 includes an exhaust manifold (not shown) through which exhaust gas exiting the combustion chamber flows and an exhaust pipe 11 connected to the exhaust manifold. The exhaust pipe 11 runs under the floor of the vehicle 1 toward the rear of the vehicle 1 and is disposed so that the downstream end of the exhaust pipe 11 opens to the rear of the vehicle. A manifold catalyst 12 such as a three-way catalyst is provided immediately after the joining portion of the exhaust manifold, and a main catalyst 13 such as a three-way catalyst is provided in the exhaust pipe 11 below the floor. A muffler 14 is provided at the downstream end of the exhaust pipe 11. On the other hand, a radiator 14 and a radiator fan 15, which are parts for cooling the engine, are disposed in front of the vehicle 1.

  The vehicle 1 includes an exhaust heat utilization device 21. The exhaust heat utilization device 21 includes an exhaust heat recovery device 22, a heat exchanger 31, a rear heater 41, cooling water passages 61, 62, 63 that connect these, and a water pump 71. Here, although cooling water is used as a refrigerant, it is not limited to cooling water.

  The exhaust heat recovery unit 22 is provided in the exhaust pipe 11 on the downstream side of the main catalyst 13 and in the vicinity of the rear differential 5. The reason why the exhaust heat recovery device 22 is provided in the exhaust pipe 11 downstream of the main catalyst 13 is as follows. That is, since the main catalyst 13 does not function unless the activation temperature is reached (it cannot purify harmful components), it is necessary to always warm the main catalyst 13 to the activation temperature with exhaust heat (heat of exhaust). If the exhaust heat recovery device 22 is provided on the upstream side of the main catalyst 13, the exhaust temperature decreases downstream of the exhaust heat recovery device 22, which may affect the function of the main catalyst 13. If the exhaust heat downstream of the main catalyst 13 is effectively used, the function of the main catalyst 13 is not affected. Therefore, the exhaust heat recovery device 22 is provided on the downstream side of the main catalyst 13.

  Next, the exhaust heat recovery unit 22 is provided in the exhaust pipe 11 near the rear differential 5 for the following reason. That is, the exhaust pipe 11 downstream of the main catalyst 13 is often disposed near the rear differential 5 in terms of the vehicle layout. Therefore, it is considered that the heat exchanger 31 is provided in the rear differential 5 and the cooling water heated by the exhaust heat recovery device 22 is guided to the heat exchanger 31 to promote the warm-up of the rear differential 5. Then, the exhaust heat recovery device 22 is located near the heat exchanger 31 and the cooling water passage 62 connecting the exhaust heat recovery device 22 and the heat exchanger 31 is shortened, so that the heat radiation from the cooling water passage 62 is minimized. It is also better to make it. Therefore, the exhaust heat recovery device 22 is provided in the exhaust pipe 11 in the vicinity of the rear differential 5.

  As shown in FIG. 2, the exhaust heat recovery unit 22 includes a cylindrical main body 23 that surrounds the outer periphery of the exhaust pipe 11, and a water jacket 24 (refrigerant passage) provided inside the main body 23. The water jacket 24 is provided with an inlet 25 and an outlet 26. The water jacket inlet 25 is connected to the cooling water passage 61, and the water jacket outlet 26 is connected to the cooling water passage 62. The cooling water enters the water jacket 24 from the inlet 25, flows through the water jacket 24, and exits from the outlet 26. In the exhaust heat recovery unit 22, heat exchange is performed between the cooling water flowing through the water jacket 24 and the exhaust flowing through the exhaust pipe 11, and the heat of the exhaust is recovered into the cooling water. The heat recovered in this way and warmed is sent to the heat exchanger 31 through the cooling water passage 62.

  The heat exchanger 31 is provided with a heat exchanger body 32 on the outer periphery of the housing 5A (differential case) of the rear differential 5 so as to cover the entire outer periphery of the lower half of the rear differential 5, for example. The rear differential 5 includes a housing 5A and a gear mechanism (not shown) housed therein. The gear mechanism transmits the rotation of the propeller shaft 4 to two drive shafts 6 and 6 arranged orthogonal to the shaft 4. The housing 5A contains gear oil, which is hydraulic oil, at approximately half the liquid level.

  As shown in FIG. 2, the heat exchanger 31 includes a main body 32 and a water jacket 33 (refrigerant passage) provided inside the main body 32. The water jacket 33 is provided with an inlet 34 and an outlet 35. The water jacket inlet 34 is connected to the cooling water passage 62, and the water jacket outlet 35 is connected to the cooling water passage 63. The cooling water heated by the exhaust heat recovery device 22 enters the water jacket 33 from the inlet 34, flows through the water jacket 33, and exits from the outlet 35. In the heat exchanger 31, heat is exchanged between the heated cooling water flowing through the water jacket 33 and the gear oil stored in the housing 5A (hereinafter referred to as "gear oil inside the rear differential") to obtain the cooling water. The gear oil inside the rear differential is heated with the heat of. This promotes warming up of the rear differential 5. In this way, the cooling water releases heat to the gear oil inside the rear differential, so that the temperature of the cooling water (hereinafter also referred to as “cooling water temperature”) decreases. The cooling water whose temperature has decreased is sent to the rear heater 41 via the cooling water passage 63.

  An air conditioner (not shown) capable of cooling and heating the room is mainly provided on the cab side. On the other hand, the rear heater 41 (heater) is provided on the rear seat side, for example, separately from the air conditioner. The rear heater 41 is provided separately from the air conditioner, and the two can work together, so that the entire room can be heated at an early stage. Or it becomes possible to respond to the indoor heating request | requirement of the rear seat side. Providing the rear heater 41 on the rear seat side in this way is particularly useful in a one-box car with a large indoor space. Here, the case where the room heating request on the rear seat side is met will be described. Since the rear heater 41 is basically for indoor heating on the rear seat side, it handles air. Here, considering the interior of the rear seat side, the air in the rear seat side is referred to as “inside air on the rear seat side”, and the air outside the passenger compartment including the rear seat side and the driver seat side is referred to as “outside air”.

  As shown in FIG. 2, the main part of the rear heater 41 includes a duct 42, a heater core 43, a blower fan 46, and an outside / inside air selection mechanism 47. By providing the rear heater 41 on the rear seat side, both the cooling water passage 63 connecting the heat exchanger 31 and the heater core 43 and the cooling water passage 61 connecting the heater core 43 and the exhaust heat recovery device 22 can be shortened. As described above, the exhaust heat utilization device 21 can be made compact by arranging the exhaust heat recovery device 22, the heat exchanger 31, and the rear heater 41 together under the floor behind the vehicle and on the rear seat side.

  If the duct 42 for flowing air (outside air and rear seat side air) is, for example, cylindrical, the heater core 43 is formed, for example, in a thin cylindrical shape as a whole so as to partition the cross section of the duct 42. Be placed. The heater core 43 includes a main body that supports a large number of tubes (refrigerant passages) through which cooling water flows and fins disposed around the tubes, so that air can pass through the outer periphery of the tubes. A heater core 43 having a known shape or structure may be employed. The heater core 43 itself is well known and will not be described in detail. The heater core 43 is provided with an inlet 44 and an outlet 45. The inlet 44 is connected to the cooling water passage 63, and the outlet 45 is connected to the cooling water passage 61. Cooling water enters from the inlet 44 and flows through a number of tubes and exits from the outlet 45.

  A blower fan 46 is provided immediately downstream of the heater core 43. The actuator of the blower fan 46 is a motor, for example. The rotational speed of the blower fan 46 can be changed by controlling the motor. When the blower fan 46 is driven, air passes in one direction along the outer periphery of the tube of the heater core 43 from the upstream side (left side in FIG. 2) to the downstream side (right side in FIG. 2). At this time, in the heater core 43, heat exchange is performed between the cooling water flowing through the tube and the air passing through the outer periphery of the tube.

  The outside air selection mechanism 47 selectively switches between the three modes of the first mode, the second mode, and the third mode. In the first mode, when the blower fan 46 is driven, heat is exchanged with the cooling water flowing through the heater core 43 through the outside air through the heater core 43, and the outside air after the heat exchange is outdoor. It is a mode to release to The reason why the first mode is necessary is as follows. That is, when the exhaust heat utilization device 21 is provided, even if the exhaust heat recovery device 22 is provided downstream of the main catalyst 13 (downstream of the exhaust passage 11), the exhaust heat recovery device is used in a high load region of the engine. Since the exhaust gas introduced into 22 becomes high temperature, the cooling water exiting the exhaust heat recovery device 22 also becomes high temperature. Therefore, it is necessary to consider in advance measures for high water temperature.

  In detail, when the engine is in a high load range, the gear mechanism inside the rear differential 5 should also be fully working, the gear mechanism generates a lot of heat, and the temperature of the gear oil inside the rear differential Rises. On the other hand, since the exhaust heat recovery unit 22 recovers heat from the high-temperature exhaust, the temperature of the cooling water exiting the exhaust heat recovery unit 22 is higher than when the engine is outside the high load range. Even though the gear mechanism inside the rear differential 5 is actively generating heat and the temperature of the gear oil is rising, if the heat of the increased cooling water is continuously applied to the gear oil inside the rear differential in the heat exchanger 31, the gear oil There is a risk of boiling (vaporization). If even a part of the gear oil inside the rear differential boils, the efficiency of lubricating the gear mechanism inside the rear differential 5 is lowered (reliability is lowered).

  Therefore, a water temperature sensor 82 is provided at the outlet of the heat exchanger 31, and it is determined based on the cooling water temperature detected by the water temperature sensor 82 whether or not the engine is in a high load range. Here, as the engine load increases, the temperature of the exhaust gas introduced into the exhaust heat recovery unit 22 increases. It can be said that the temperature of the cooling water at the outlet of the heat exchanger 31 is substantially proportional to the engine load or the temperature of the exhaust gas introduced into the exhaust heat recovery unit 22. Then, when it is determined from the temperature of the cooling water at the outlet of the heat exchanger 31 that the engine is in a high load region, the outside / inside air selection mechanism 47 is switched to the position of the first mode. As a result, when the temperature of the outside air is lower than the cooling water flowing through the tube of the heater core 43, heat is transferred from the cooling water flowing through the tube of the heater core 43 to the outside air flowing around the outer periphery of the tube of the heater core 43. Water temperature decreases. It is possible to cool the gear oil inside the rear differential by guiding the cooling water whose temperature has dropped to the heat exchanger 31 and performing heat exchange between the cooling water whose temperature has dropped and the gear oil inside the rear differential. In this way, the first mode is provided because the exhaust becomes high temperature even in the high load region of the engine even downstream of the exhaust pipe 11, and the amount of heat recovered by the exhaust heat recovery unit 22 becomes excessive. This is for this measure.

  In the second mode, when the blower fan 46 is driven, heat is exchanged between the heater core 43 and the cooling water flowing through the tube of the heater core 43 through the inside air on the rear seat side. This is a mode to return the inside air to the room on the rear seat side. For example, when a request for room heating on the rear seat side is made and the temperature of the cooling water flowing through the tube of the heater core 43 is higher than the inside air on the rear seat side, the outside / inside air selection mechanism 47 is switched to the second mode. As a result, heat is transferred from the cooling water flowing through the tube to the inside air flowing through the outer periphery of the tube of the heater core 43, so that indoor heating on the rear seat side can be performed. As described above, the outside air selection mechanism 47 can selectively switch between the first mode and the second mode when the blower fan 46 is driven.

  The third mode is a mode in which the operation of the outside / inside air selection mechanism 47 is stopped when the blower fan 46 is not driven.

  Next, the outside / inside air selection mechanism 47 will be described in detail. The outside / inside air selection mechanism 47 mainly includes four chambers 48, 49, 52, 53 and two interlocking three-position valves 50, 54. In order to introduce the outside air or the inside air on the rear seat side into the heater core 43, an outside air room 48 for introducing outside air on the upstream side of the heater core 41 and an inside air room 49 for introducing the inside air on the rear seat side are located above and below the duct 42. It is partitioned. Here, the outside air chamber 48 communicates with the atmosphere outside the room (outside the vehicle compartment) via a duct (not shown). The inside air room 49 communicates with the room on the rear seat side through a duct (not shown).

  Corresponding to the three modes of the outside / inside air selection mechanism 47, the first three-position valve 50 can take three positions: an intermediate position, an inside air side position, and an outside air side position. For example, FIG. 4 shows the case where the first three-position valve 50 is in the intermediate position, FIG. 5 shows the case where the first three-position valve 50 is in the inside air side position, and FIG. 6 shows the case where it is in the outside air side position. The actuator 51 of the first three-position valve 50 is, for example, a motor. A mechanism for converting the rotational movement of the motor into the movement of the first three-position valve 50 is provided. When the actuator 51 is not receiving a drive signal, the first three-position valve 50 is in an intermediate position that is a neutral position. When in the intermediate position, both the outside air room 48 and the inside air room 49 are in communication with the upstream side of the heater core 43 as shown in FIGS. When the actuator 51 of the first three-position valve 50 receives a drive signal for instructing the inside air side position and the first three position valve 50 moves to the inside air side position, as shown in FIG. Only the inside air is introduced into the heater core 43. On the other hand, when the actuator 51 of the first three-position valve 50 receives a drive signal instructing the outside air side position and the first three position valve 50 moves to the outside air side position, the outside air in the outside air chamber 48 is shown in FIG. Only the heater core 43 is introduced.

  In order to release the air that has exited the heater core 43 to the outside air or return it to the room on the rear seat side, an outside air communication room 52 that communicates with the outside air on the downstream side of the heater core 43 and an indoor communication room that communicates with the room on the rear seat side 53 is partitioned above and below the duct 42. Here, the outside air communication room 52 communicates with the atmosphere outside the room (outside the passenger compartment) via a duct (not shown). The indoor communication room 53 communicates with the room on the rear seat side through a duct (not shown).

  Similarly to the first three-position valve 50, the second three-position valve 54 can take three positions: an intermediate position, an inside air side position, and an outside air side position. For example, FIG. 4 shows when the second three-position valve 54 is in the intermediate position, FIG. 5 shows when it is in the inside air position, and FIG. 6 shows when it is in the outside air position. The actuator 55 of the second three-position valve 54 is also a motor, for example. A mechanism for converting the rotational movement of the motor into the movement of the second three-position valve 54 is provided. The second three-position valve 54 is driven in conjunction with the first three-position valve 50. When the actuator 55 is not receiving a drive signal, the second three-position valve 54 is in an intermediate position that is a neutral position. When in the intermediate position, both the outside air communication room 52 and the indoor communication room 53 communicate with the downstream side of the heater core 43 as shown in FIGS. When the actuator for the second three-position valve 54 receives a drive signal indicating the inside air side position and the second three position valve 54 moves to the inside air side position, the second three position valve 54 also moves as shown in FIG. Move to the inside air position. On the other hand, when the actuator 55 of the second three-position valve 54 receives a drive signal indicating the outside air side position and the second three position valve 54 moves to the outside air position, the second three position valve as shown in FIG. 54 also moves to the outside air position.

  The three cooling water passages 61, 62, and 63 (external refrigerant passages) form a closed circuit together with the water jacket 24 of the exhaust heat recovery unit 22, the water jacket 33 of the exhaust heat recovery unit 31, and the tube of the heater core 43. It is composed. Among these, the cooling water passage 61 is provided with a water pump 71 (pump). The position where the water pump 71 is provided is not limited to the cooling water passage 61. The actuator of the water pump 71 is, for example, a motor. The rotational speed of the water pump 71 can be changed by controlling the motor. When the water pump 71 is driven, the cooling water circulates through the three cooling water passages 61, 62, 63 and the water jacket 24 of the exhaust heat recovery unit 22, the water jacket 33 of the heat exchanger 31, and the tube of the heater core 43.

  In this way, by configuring the exhaust heat utilization device 21, the exhaust oil recovered by the exhaust heat recovery unit 22 after the engine is cold-started is used to warm the gear oil inside the rear differential, or the heater core 43 is used as a heat source. The interior of the rear seat side can be heated. On the other hand, the cooling water is cooled using the heater core 43 as a radiator in a high load region of the engine, and the gear oil inside the rear differential can be cooled by guiding it to the heat exchanger 31.

  A blower fan 46 and two three-position valves according to a request for warming up of the rear differential 5 after the cold start of the engine and a request for heating of the rear seat side, and a request for cooling the gear oil in the rear differential in a high load range. In order to control the water pump 71, a control device 81 is provided. The control device 81 receives an actual cooling water temperature signal from the water temperature sensor 82 and a rear seat heating request signal from the heating switch 83. The water temperature sensor 82 is for detecting the cooling water temperature at the outlet of the heat exchanger 31. The heating switch 83 is provided in the passenger compartment on the rear seat side. When the passenger on the rear seat side wants to operate the rear heater 41 and switches the heating switch 83 from OFF to ON, this ON signal is transmitted to the control device 81 as a signal that there is a heating request for heating the room on the rear seat side. It is like that.

  The control device 81 is constituted by a microcomputer, for example. In the control device 81, the blower fan 46, the two three-position valves 50 and 54, and the water pump 71 depending on whether there is a heating request on the rear seat side and the cooling water temperature at the outlet of the heat exchanger 31 detected by the water temperature sensor 82. To control.

  Next, the control method of the exhaust heat utilization device 21 performed in the control device 81 will be described. FIG. 3 summarizes the control method of the exhaust heat utilization device. Here, the entire operating range of the engine is targeted. In order to utilize the exhaust heat utilization device 21 in the entire operation region of the engine, two water temperature determination threshold values T1 [° C.] and T2 [° C.] (T1 <T2) are introduced. First, one water temperature determination threshold value T1 (second predetermined value) is a threshold value for determining whether or not to prioritize the warm-up promotion of the rear differential 5 over the heating request on the rear seat side after the cold start of the engine or the like. It is. Assuming that the actual cooling water temperature at the outlet of the heat exchanger 31 is T [° C.], it is necessary to prioritize the warm-up of the rear differential 5 over the heating requirement on the rear seat side when T <T1. There is a state where it is necessary to satisfy both the warm-up promotion of the rear differential 5 and the heating requirement on the rear seat side in the temperature range of T1 ≦ T.

  Next, the other water temperature determination threshold value T2 (first predetermined value) is used to determine whether heating of the rear seat side is unnecessary and cooling of the gear oil in the rear differential is necessary in a high engine load range. Is the threshold value. When T <T2, the rear seat side heating requirement and the rear differential 5 need to be warmed up. When T2 ≦ T, the rear seat side heating is unnecessary and gear oil in the rear differential is required. It will be in the state which needs to be cooled.

  Here, the reason why the heating of the rear seat side becomes unnecessary when the temperature range of T2 ≦ T is as follows. That is, the air conditioner provided on the driver's seat side also has a heater core (not shown). Cooling water whose temperature has risen after the engine has been warmed up is mainly led to the radiator 14 to be cooled, while a part of the cooling water whose temperature has risen is introduced into the heater core for indoor heating. Has been. In the temperature range of T2 ≦ T, the temperature of the cooling water introduced into the heater core for indoor heating increases. When the air conditioner is operated in the temperature range of T2 ≦ T, not only the driver seat side room but also the rear seat side room is heated by the warm air from the heater core for indoor heating. In the temperature range of T2 ≦ T, heating on the rear seat side is performed by the air conditioner provided on the driver's seat side without responding to the heating request on the rear seat side (that is, the heating request only on the rear seat side). . Therefore, heating in the rear seat side is not necessary when T2 ≦ T. Again, this does not mean that the rear seat is not heated or that the rear seat cannot be heated.

  As a result, the cooling water temperature at the outlet of the heat exchanger is divided into three temperature ranges: a temperature range of T <T1, a temperature range of T1 ≦ T <T2, and a temperature range of T2 ≦ T. That is, the temperature range of T <T1 (hereinafter referred to as “first temperature range”) is a temperature range in which it is necessary to prioritize the warm-up promotion request for the rear differential 5 over the heating request for the rear seat. The temperature range of T1 ≦ T <T2 (hereinafter, referred to as “second temperature range”) is a temperature range in which it is necessary to satisfy both the warm-up promotion request for the rear differential 5 and the heating requirement for the rear seat. A temperature range of T2 ≦ T (hereinafter, referred to as “third temperature range”) is a temperature range in which heating of the rear seat side is unnecessary and the gear oil in the rear differential needs to be cooled.

  In this way, the requirements differ depending on each of the three temperature ranges. For this reason, as shown in the right half of FIG. 3, when there is a heating request for heating the interior of the rear seat side, the control mode 1 is set in the first temperature range, the control mode 2 is set in the second temperature range, Control mode 3 is executed in three temperature ranges. Further, as shown in the left half of FIG. 3, when there is no heating request for heating the interior of the rear seat side, the control mode 1 is performed in the first and second temperature ranges, and the control mode 3 is performed in the third temperature range. To do.

  Hereinafter, the control modes 1, 2, and 3 will be described in order with reference to FIGS. FIG. 4 shows the state of the exhaust heat utilization device 21 in the control mode 1 as a model. As described above, the first temperature range is a temperature range in which it is necessary to prioritize the warm-up promotion request for the rear differential 5 over the heating request for the rear seat. Here, the reason why the warm-up promotion request for the rear differential 5 is prioritized over the heating request for the rear seat side is as follows. That is, the first temperature region is when the cooling water temperature at the outlet of the heat exchanger is low, such as immediately after the cold start of the engine. Even if there is a request for heating on the rear seat side, even if the cooling water temperature at the outlet of the heat exchanger is low, if the outside / inside air selection mechanism 47 is switched to the second mode, low-temperature air is generated from the rear heater 41. This is for avoiding this because it is blown out into the room on the rear seat side and the passenger on the rear seat side feels cold. In the control mode 1, the outside / inside air selection mechanism 47 is switched to the third mode. That is, the water pump 71 is turned on (driven) to promote the warm-up of the rear differential 5 by exhaust heat recovery, the blower fan 46 is turned off (stopped) to deactivate the rear heater 41, and the three-position valves 50, 54 are turned on. To the middle position.

  By driving the water pump 71, the cooling water circulates through the cooling water passages 61, 62, 63 and the water jacket 24 of the exhaust heat recovery unit 22, the water jacket 33 of the heat exchanger 31, and the tube of the heater core 43. In the exhaust heat recovery device 22, the exhaust heat is recovered in the cooling water, so that the cooling water is warmed and the warm cooling water (hot water) is guided to the heat exchanger 31. In this case, the flow rate and flow rate of the cooling water flowing through the exhaust heat recovery unit 22 are related to the amount of heat (exhaust heat recovery efficiency) recovered from the exhaust gas introduced into the exhaust heat recovery unit 22 into the cooling water. Assuming that the cross-sectional area of the cooling water passage is fixed, the efficiency becomes worse when the exhaust heat recovery unit 22 recovers the exhaust heat when the flow of the cooling water is too fast. On the contrary, when the flow is too slow, although the efficiency of recovering the exhaust heat by the exhaust heat recovery device 22 is improved, the recovery of the recovered exhaust heat to the heat exchanger 5 is delayed, so it takes time to warm up the rear differential 5. It will take. Therefore, the flow rate of the cooling water, that is, the rotational speed of the water pump 71 (hereinafter referred to as “pump rotational speed”) is obtained so that high exhaust heat recovery efficiency is obtained in the first temperature range and warming up of the rear differential 5 is promoted. ). In the heat exchanger 31, heat is exchanged between the hot water and the gear oil inside the rear differential, and the temperature of the gear oil inside the rear differential rises (warming up of the rear differential 5 is promoted). In the rear heater 41, the blower fan 46 is stopped and the three-position valves 50 and 54 are in the intermediate position, so that heating of the rear seat side by the rear heater 41 does not operate. Thus, the control mode 1 is the warm-up promotion mode of the rear differential 5.

  Next, FIG. 5 shows the state of the exhaust heat utilization device 21 in the control mode 2 as a model. As described above, the second temperature range is a temperature range in which it is necessary to satisfy both the warm-up promotion request for the rear differential 5 and the heating requirement for the rear seat. Therefore, in the control mode 2, the outside / inside air selection mechanism 47 is switched to the second mode. That is, in order to promote warm-up of the rear differential 5 by exhaust heat recovery and to heat the rear seat side, the water pump 71 is turned on (drive), the blower fan 46 is turned on (drive), and the three-position valves 50, 54 are turned on. To the inside air position.

  By driving the water pump 71, the cooling water circulates through the cooling water passages 61, 62, 63 and the water jacket 24 of the exhaust heat recovery unit 22, the water jacket 33 of the heat exchanger 31, and the tube of the heater core 43. In this case, since the temperature of the exhaust gas introduced into the exhaust heat recovery unit 22 is higher than that in the first temperature range, the amount of heat recovered in the cooling water by the exhaust heat recovery unit 22 increases. Therefore, in the second temperature range, the flow rate of the cooling water, that is, the pump rotation speed is adapted so that the warm-up promotion of the rear differential 5 is efficiently performed. In the exhaust heat recovery device 22, the exhaust heat is recovered in the cooling water, so that the cooling water is warmed and the warm cooling water (hot water) is guided to the heat exchanger 31. In the heat exchanger 31, heat is exchanged between the hot water and the gear oil inside the rear differential, and the temperature of the gear oil inside the rear differential rises (warming up of the rear differential 5 is promoted).

  4 and 5, the amount of heat recovered in the cooling water by the exhaust heat recovery unit 22 is larger in FIG. 5 due to the higher temperature of the exhaust gas introduced into the exhaust heat recovery unit 22. The cooling water temperature at the outlet becomes higher. This increased warm water is guided to the heater core 43 of the rear heater 41. That is, the temperature of the cooling water flowing through the tube of the heater core 43 becomes higher than in the case of FIG. In the rear heater 41, since the blower fan 46 is driven and the two three-position valves 50 and 54 are in the inside air side position, heat exchange is performed between the inside air on the rear seat side passing through the heater core 43 and the hot water. . At this time, since the warm water flowing through the tube is higher than that in the case of FIG. 4, it is warmer than the inside air, so the temperature of the inside air on the rear seat side rises (the heating on the rear seat side operates). In this case, the flow rate of the inside air flowing around the outer periphery of the tube is related to the amount of heat that can be taken from the cooling water flowing through the tube, and the amount of heat that can be taken from the cooling water increases as the flow rate of the inside air increases. On the other hand, the higher the flow rate of the inside air is, the better, and even if the flow rate of the inside air is increased too much, the efficiency of taking heat from the cooling water decreases. Therefore, the flow rate of the inside air, that is, the rotation speed of the blower fan 46 (hereinafter referred to as “fan rotation speed”) is set so that the amount of heat that can be taken from the cooling water flowing through the tube of the heater core 43 in the second temperature range is maximized. Fits. The cooling water whose temperature has been lowered by flowing through the tube of the heater core 43 is returned to the exhaust heat recovery unit 22, and the exhaust heat is recovered again into the cooling water. Thus, the control mode 2 is a mode in which warm-up promotion of the rear differential 5 and heating of the rear seat side are both performed.

  Next, FIG. 6 shows the state of the exhaust heat utilization device 21 in the control mode 3 as a model. As described above, the third temperature range is a temperature range in which the heating of the rear seat side is unnecessary and the gear oil in the rear differential needs to be cooled. In the control mode 3, the outside air selection mechanism 47 is switched to the first mode. That is, in order to cool the gear oil in the rear differential, the water pump 71 is turned on (drive), the blower fan 46 is turned on (drive), and the three-position valves 50 and 54 are set to the outside air side position.

  By driving the water pump 71, the cooling water circulates through the cooling water passages 61, 62, 63 and the water jacket 24 of the exhaust heat recovery unit 22, the water jacket 33 of the heat exchanger 31, and the tube of the heater core 43. In this case, the temperature of the cooling water introduced into the tube of the heater core 43 is higher than that in the second temperature range. For this reason, it is considered that the amount of heat that can be taken away from the cooling water flowing through the tube is not maximized when the outside air flowing around the tube has the same flow rate as the inside air in the second temperature range. Therefore, the flow rate of outside air, that is, the fan rotation speed is adapted so that the amount of heat that can be taken from the cooling water flowing through the tube is maximized even in the third temperature range. In the rear heater 41, since the blower fan 46 is driven and the two three-position valves 50 and 54 are in the outside air position (the heating on the rear seat side is not activated), the outside air passing through the outer periphery of the tube of the heater core 43, Heat exchange is performed between the hot water flowing through the tube and the cooling water temperature is lowered. The cooling water (cold water) whose temperature has decreased is returned to the exhaust heat recovery unit 22.

  Here, the temperature of the cooling water at the outlet of the heat exchanger is substantially proportional to the temperature of the exhaust gas introduced into the exhaust heat recovery unit 22. If the rotational speed of the water pump 71 is constant in FIG. 5 and FIG. 6, the exhaust heat recovery unit 22 recovers the cooling water to the cooling water by the amount of the exhaust gas introduced into the exhaust heat recovery unit 22 in FIG. The amount of heat generated increases. Even if the heater core 43 is used as a radiator and the temperature of the cooling water becomes high, the amount of heat recovered in the cooling water by the exhaust heat recovery device 22 increases. The effect of lowering the temperature of the cooling water will be diminished. In order to prevent this from happening, even if the temperature of the exhaust gas introduced into the exhaust heat recovery device 22 is higher in FIG. 6, the amount of heat recovered in the cooling water by the exhaust heat recovery device 22 is minimized. is there. For that purpose, it is conceivable to make the flow rate of the cooling water flowing through the exhaust heat recovery device 22 faster than that in the case of FIG. When the flow rate of the cooling water is increased, the cooling water flows before the exhaust heat recovery unit 22 recovers the exhaust heat to the cooling water, and the amount of heat recovered in the cooling water by the exhaust heat recovery unit 22 is reduced. It is. Therefore, the amount of heat recovered in the cooling water by the exhaust heat recovery unit 22 is reduced as much as possible, and the cooling water flowing through the exhaust heat recovery unit 22 is introduced into the heat exchanger 31 so that the cooling water whose temperature has been reduced without being recovered as much as possible is introduced into the heat exchanger 31. The flow rate of the pump, that is, the pump rotation speed is adapted. In the heat exchanger 31, heat is exchanged between the cooling water thus lowered in temperature and the gear oil inside the rear differential, and the temperature of the gear oil inside the rear differential is reduced. Thus, the control mode 3 is a cooling mode for the gear oil inside the rear differential.

  FIG. 7 shows a model of the pump rotation speed suitable for each of the three temperature ranges. As shown by a solid line in FIG. 7, the pump rotation speed in the first temperature range is, for example, a predetermined value a, the pump rotation speed in the second temperature range is, for example, a predetermined value b, and the pump rotation speed in the third temperature range is For example, the predetermined value c. Thus, the pump rotation speed is a stepwise value with respect to the cooling water temperature. Similarly, FIG. 8 shows a model of the fan rotation speed that fits in the second and third temperature ranges. As indicated by the solid line in FIG. 8, the fan rotation speed in the first temperature range is zero, the fan rotation speed in the second temperature range is, for example, a predetermined value e, and the fan rotation speed in the third temperature range is, for example, a predetermined value. f. Thus, the fan rotation speed has a stepwise value with respect to the cooling water temperature.

  Next, the control performed by the control device 81 will be described with reference to the flowcharts of FIGS. 9A and 9B. 9A and 9B are executed at regular time intervals (for example, every 10 ms).

  In step 1, it is determined whether or not the exhaust heat utilization system of the present embodiment can be started after the engine is cold started. If the exhaust heat utilization system of this embodiment is not in a state where it can be started, the current process is terminated. Eventually, when it becomes possible to start the exhaust heat utilization system of this embodiment in step 1, the process proceeds to step 2 to see whether there is a heating request on the rear seat side. If the heating switch 83 is ON, it is determined that there is a request for heating on the rear seat side. If the heating switch 83 is OFF, it is determined that there is no request for heating on the rear seat side.

  When it is determined that there is a heating request on the rear seat side, the process proceeds to Steps 3 and 4, and the cooling water temperature T [° C.] at the outlet of the heat exchanger 31 detected by the water temperature sensor 82 and the water temperature determination thresholds T1 and T2 [° C.] are set. Compare. The water temperature determination threshold values T1 and T2 are considered to be different for each engine specification and for each vehicle specification in which the engine is mounted. When the cooling water temperature T at the outlet of the heat exchanger 31 is lower than the water temperature determination threshold T1, it is determined that the temperature is in the first temperature range. When the cooling water temperature at the outlet of the heat exchanger 31 is equal to or higher than the water temperature determination threshold T1 and lower than the water temperature determination threshold T2, it is in the second temperature range, and when the cooling water temperature T at the outlet of the heat exchanger 31 is equal to or higher than the water temperature determination threshold T2. Judged to be in the 3 temperature range. When the cooling water temperature at the outlet of the heat exchanger is in the first temperature range, the cooling water temperature at the outlet of the heat exchanger is at Steps 5 to 9 and when the cooling water temperature at the outlet of the heat exchanger is in the second temperature range, at Steps 10 to 14. When it is in the third temperature range, the routine proceeds to steps 15-19.

  In steps 5, 6 and 7 that proceed when the temperature is in the first temperature range, the control mode 1 is set, so that the water pump 71 is turned on, the blower fan 46 is turned off, and the two three-position valves 50 and 54 are set to the intermediate positions. .

  In step 8, a predetermined value a is entered in the pump rotation speed. The predetermined value a determines the flow rate of the cooling water flowing through the exhaust heat recovery unit 22, and is adapted to obtain a high exhaust heat recovery efficiency in the first temperature range and to promote the warm-up of the rear differential 5. Yes. Thereby, the warm-up promotion request for the rear differential 5 can be prioritized over the heating request for the rear seat. In step 9, zero is set for the fan rotation speed.

  In steps 10, 11, and 12 that proceed when the temperature is in the second temperature range, control mode 2 is set, so water pump 71 is turned on, blower fan 46 is turned on, and two three-position valves 50 and 54 are brought to the inside air side position. To do.

  In step 13, a predetermined value b is entered into the pump rotation speed. The predetermined value b determines the flow rate of the cooling water. In the second temperature range, the amount of heat recovered in the cooling water by the exhaust heat recovery unit 22 increases, and the warming up of the rear differential 5 is promoted and the rear seat side room heating is performed. Is adapted to be done efficiently. In step 14, a predetermined value e is entered into the fan rotation speed. The predetermined value e determines the flow rate of the inside air, and is adapted so that heat can be efficiently taken from the tube of the heater core 43 in the second temperature range and sent to the room on the rear seat side. Thus, both the warm-up promotion request for the rear differential 5 and the heating request for the rear seat can be satisfied.

  In steps 15, 16, and 17 that proceed when the temperature is in the third temperature range, control mode 3 is set, so that the water pump 71 is turned on, the blower fan 46 is turned on, and the two three-position valves 50 and 54 are moved to the outside air position. To do.

  In step 18, a predetermined value c is entered into the pump rotation speed. The predetermined value c determines the flow rate of the cooling water. In the third temperature range, the amount of heat collected in the cooling water by the exhaust heat recovery unit 22 decreases, and the temperature of the cooling water introduced into the heat exchanger 31 decreases. The gear oil in the rear differential is adapted to be cooled efficiently. In step 19, a predetermined value f is entered into the fan rotation speed. The predetermined value f is adapted so that heat can be efficiently taken from the tube of the heater core 43 and released to the outside air in the third temperature range. As a result, the gear oil inside the rear differential can be cooled.

  In this case, since the outside air selection mechanism 47 is set to the first mode in spite of a request for heating on the rear seat side, the rear heater 41 does not perform indoor heating on the rear seat side. However, if the air conditioner provided on the driver's seat side is in an activated state, there is no problem because the air conditioner heats not only the driver's seat interior but also the rear seat interior.

  When it is determined in step 2 that there is no request for heating on the rear seat side, the process proceeds to steps 20 and 21, and the cooling water temperature T [° C.] at the outlet of the heat exchanger 31 detected by the water temperature sensor 82 and the water temperature determination thresholds T1 and T2 [° C.]. Compare When the cooling water temperature T at the outlet of the heat exchanger 31 is lower than the water temperature determination threshold T1, it is determined that the temperature is in the first temperature range. When the cooling water temperature at the outlet of the heat exchanger 31 is equal to or higher than the water temperature determination threshold T1 and lower than the water temperature determination threshold T2, it is in the second temperature range, and when the cooling water temperature T at the outlet of the heat exchanger 31 is equal to or higher than the water temperature determination threshold T2. Judged to be in the 3 temperature range. When the cooling water temperature at the outlet of the heat exchanger is in the first temperature range, the cooling water temperature at the heat exchanger outlet is at steps 22 to 26, and when the cooling water temperature at the outlet of the heat exchanger is in the second temperature range, at steps 27 to 31. When it is in the third temperature range, the process proceeds to steps 32-36.

  In steps 22, 23, and 24 that proceed when the temperature is in the first temperature range, control mode 1 is set, so that the water pump 71 is turned on, the blower fan 46 is turned off, and the two three-position valves 50 and 54 are set to the intermediate positions. .

  In step 25, a predetermined value a is entered in the pump rotation speed. The predetermined value a determines the flow rate of the cooling water flowing through the exhaust heat recovery unit 22, and is adapted to obtain a high exhaust heat recovery efficiency in the first temperature range and to promote the warm-up of the rear differential 5. Yes. Thereby, the warm-up promotion request for the rear differential 5 can be prioritized over the heating request for the rear seat. In step 26, zero is set for the fan rotation speed.

  In order to set the control mode 1 in steps 27, 28, and 29 that proceed when the temperature is in the second temperature range, the water pump 71 is turned on, the blower fan 46 is turned off, and the three-position two valves 50, 54 are set to the inside air intermediate position. To. In steps 30 and 31, as in steps 25 and 26, a predetermined value a is set for the pump rotation speed and zero is set for the fan rotation speed. The reason why the control mode 1 is set when there is no request for heating on the rear seat side is that there is no request for heating on the rear seat side, and therefore it is only necessary to promote warm-up of the rear differential 5.

  In steps 32, 33, and 34 that proceed when the temperature is in the third temperature range, control mode 3 is set, so that water pump 71 is turned on, blower fan 46 is turned on, and two three-position valves 50 and 54 are moved to the outside air position. To do.

  In step 35, a predetermined value c is entered into the pump rotation speed. The predetermined value c determines the flow rate of the cooling water. In the third temperature range, the amount of heat collected in the cooling water by the exhaust heat recovery unit 22 decreases, and the temperature of the cooling water introduced into the heat exchanger 31 decreases. The gear oil in the rear differential is adapted to be cooled efficiently. In step 36, a predetermined value f is entered into the fan rotation speed. The predetermined value f is adapted so that heat can be efficiently taken from the tube of the heater core 43 and released to the outside air in the third temperature range. As a result, the gear oil inside the rear differential can be cooled.

  In this case, since there is no heating request for heating the room on the rear seat side, there is no problem even if the outside / inside air selection mechanism 47 is set to the first mode.

  In a flow (not shown), the ON / OFF signal for the water pump 71 determined in this way is output to the water pump 71, and the ON / OFF signal for the blower fan 46 determined in this way is output to the blower fan 46. Further, the control amount is set to the actuator (motor) of the water pump 71 so that the pump rotation speed set in this way is obtained, and the control amount is set to the blower fan 46 so that the fan rotation speed set in this way is obtained. Output to the actuator (motor).

  Here, the effect of this embodiment is demonstrated.

The exhaust heat utilization system of the present embodiment includes an exhaust heat recovery device 22, a heat exchanger 31, a heater core 43, a blower fan 46, cooling water passages 61, 62, 63 (refrigerant passage), and a water pump 71. (Pump) and a control device 81 (control unit). The exhaust heat recovery unit 22 is provided in the exhaust pipe 11 in the vicinity of the housing 5A (differential case) of the rear differential 5 in which gear oil is enclosed, and performs heat exchange between the exhaust flowing through the exhaust pipe 11 and cooling water (refrigerant). Can be done. The heat exchanger 31 is provided in the housing 5A of the rear differential 5 and can perform heat exchange between the gear oil and the cooling water. The heater core 43 can exchange heat between air and cooling water. The blower fan 46 allows air to pass through the heater core 43 in one direction. The cooling water passages 61, 62, 63 connect the exhaust heat recovery unit 22, the heat exchanger 31, and the heater core 43. The water pump 71 circulates cooling water through the cooling water passages 61, 62, 63. The control device 81 executes the control mode 3 when the temperature of the cooling water is in the third temperature range (a temperature range higher than a predetermined first predetermined value).
The control mode 3 is a first mode in which the pump 71 and the blower fan 46 are driven, the outside air is passed through the heater core 43 to exchange heat with the cooling water, and the outside air after the heat exchange is discharged to the outside. To do.
In this embodiment, when the cooling water becomes high temperature in a high load region of the engine, the heater core 43 can be used as a radiator to cool the high temperature cooling water. There is no need to provide a switching valve. Moreover, since heat is radiated from the cooling water by the heater core 43, it is possible to avoid the fear that the cooling water will boil due to insufficient heat dissipation. In addition, when the vehicle is running in a high load region of the engine, the gear oil inside the rear differential 5 can be overheated when the gear mechanism inside the rear differential 5 rotates at a high rotational speed. At this time, the cooling water whose temperature has been reduced by the heat radiation from the heater core 43 is guided to the heat exchanger 31, whereby heat exchange is performed between the cooling water whose temperature has been reduced and the gear oil inside the rear differential. When the temperature of the cooling water is lower than the superheated gear oil, the heat exchanger 31 functions as an oil cooler, and the reliability of the gear mechanism inside the rear differential 5 in the high load region can be improved.

  In the present embodiment, the control device 81 has a heating request for heating the room, and the second temperature range (a temperature lower than the first predetermined value and a predetermined second predetermined value to the first predetermined value). The control mode 2 is executed when the cooling water temperature (refrigerant temperature) is in the area. The control mode 2 is a second mode in which the pump 71 and the blower fan 46 are driven and the heater core 43 is passed through to exchange heat with the refrigerant so that the inside air after the heat exchange is returned to the room. is there. In the present embodiment, since the exhaust heat recovered by the exhaust heat recovery unit 22 can be used for indoor heating on the rear seat side, it is possible to meet the indoor heating request on the rear seat side. Further, in the heat exchanger 31, heat exchange is performed between the cooling water whose temperature has been increased by the exhaust heat recovered in the exhaust heat recovery unit 22 and the gear oil in the rear differential, thereby promoting the warm-up of the rear differential 5. I'm going. As a result, when there is a heating request for heating the room and the temperature is in the second temperature range, the viscosity of the gear oil inside the rear differential is reduced and the friction associated with the rotation of the gear mechanism inside the rear differential is reduced. Can improve fuel efficiency.

  In the present embodiment, the control device 81 executes the control mode 1 when it is in the first temperature range (the temperature range of the refrigerant is less than the second predetermined value). In other words, neither control mode 2 nor control mode 3 is executed. Here, in the control mode 2, the pump 71 and the blower fan 46 are driven as described above, the heat is exchanged with the refrigerant through the heater core 43, and the inside air after the heat exchange is returned to the room. 2 mode. In the control mode 3, the pump 71 and the blower fan 46 are driven as described above, the outside air is passed through the heater core 43 to exchange heat with the cooling water, and the outside air after the heat exchange is discharged to the outside of the room. This is a first mode. The time when the temperature is in the first temperature range is, for example, the time immediately after the engine is cold started. At this time, the gear oil inside the rear differential is at the same low temperature as the atmosphere, so the viscosity of the gear oil inside the rear differential is high and the friction when the gear mechanism inside the rear differential rotates is large. In this embodiment, warming up of the rear differential 5 can be promoted by exhaust heat by executing the control mode 1 at this time. As a result, the viscosity of the gear oil inside the rear differential is lowered by promoting the warm-up of the rear differential 5 when the vehicle is in the first temperature range.

  In the present embodiment, the control device 81 does not have a heating request for heating the room, and the second temperature range (a temperature lower than the first predetermined value and a predetermined second predetermined value to the first predetermined value). The control mode 1 is executed when the cooling water temperature (refrigerant temperature) is in the area. In other words, neither control mode 2 nor control mode 3 is executed. When there is no heating request for heating the room and there is a cooling water temperature in the second temperature range, this is the same as when there is a cooling water temperature in the first temperature range. Thereby, warm-up of the rear differential 5 can be promoted by exhaust heat. Even when there is no heating requirement for heating the room and the temperature is in the second temperature range, the warm-up of the rear differential 5 is promoted to reduce the viscosity of the gear oil inside the rear differential, so that the fuel efficiency can be improved in the vehicle's practical driving range. I can expect.

  In the present embodiment, the outside / inside air selection mechanism 47 includes an outside air room 48, an inside air room 49, a first three-position valve 50, an outside air communication room 52, an indoor communication room 53, and a second three-position valve 54. The outside air chamber 48 is on the upstream side of the heater core 43 and introduces outside air. The inside air chamber 49 is on the upstream side of the heater core 43 and introduces inside air. The first three-position valve 50 is in an intermediate position when it does not receive a drive signal, communicates the outside air chamber 48 and the heater core 43 with a drive signal indicating the outside air position, and is a drive signal indicating the inside air position. The inside air chamber 49 and the heater core 43 are communicated with each other. The outside air communication room 52 is on the downstream side of the heater core 43 and communicates with outside air. The indoor communication room 53 is on the downstream side of the heater core 43 and communicates with the room. The second three-position valve 54 is in an intermediate position when no drive signal is received, and the air that has exited the heater core 43 is introduced into the outside air communication chamber 52 by a drive signal that indicates the outside air side position, and the inside air side position is set. The air that has exited the heater core 43 is introduced into the indoor communication room 53 by a drive signal that is instructed. In this case, when the control device 81 is in the control mode 3 (first mode), it issues a drive signal indicating the outside air side position to the two three-position valves 50 and 54, and the control mode 2 (second mode). When driving, a drive signal for instructing the inside air side position is output to the two three-position valves 50 and 54. Further, when the control device 81 stops, it does not issue a drive signal to the two three-position valves 50 and 54. Accordingly, the outside / inside air selection mechanism 47 can be configured in a compact manner.

  In the present embodiment, the engine 2 having the exhaust pipe 11 is mounted in front of the vehicle 1, the exhaust pipe 11 runs under the floor of the vehicle 1 toward the rear of the vehicle 1, and the downstream end of the exhaust pipe 11 opens to the rear of the vehicle. To be arranged. A housing 5A (differential case) of the rear differential 5 is disposed under the floor behind the vehicle, and the output of the engine 2 is transmitted to the rear wheel 7 via a gear mechanism inside the rear differential 5. In this case, three of the exhaust heat recovery unit 22, the heat exchanger 31, and the rear heater 41 (heater) are arranged together at the rear of the vehicle. In the present embodiment, the exhaust heat utilization device 21 can be made compact by arranging the exhaust heat recovery device 22, the heat exchanger 31, and the rear heater 41 together at the rear of the vehicle.

  In the embodiment, the pump rotation speed and the fan rotation speed have been described as taking a step-like value (discrete value) with respect to the cooling water temperature. However, the present invention is not limited to this case. For example, the case where the pump rotation speed and the fan rotation speed take continuous values with respect to the cooling water temperature is shown in FIGS.

  Although the embodiment has been described with a rear-wheel drive vehicle, the present invention is not limited to this case. The front wheel drive vehicle includes a differential gear device in the transaxle. The present invention can be applied if the downstream side of the exhaust pipe is disposed in the vicinity of the differential gear device.

1 vehicle 2 engine 5 rear differential 5A housing (differential case)
11 Exhaust pipe 21 Waste heat utilization device (waste heat utilization system)
22 Waste heat recovery unit 23 Main body 24 Water jacket 31 Heat exchanger 32 Main body 33 Water jacket 41 Rear heater (heater)
43 heater core 46 blower fan 47 outside air selection mechanism 48 outside air room 49 inside air room 50 first three-position valve 52 outside air communication room 53 indoor communication room 54 second three-position valve 61, 62, 63 cooling water passage (refrigerant passage)
71 Water pump (pump)
81 Control device (control unit)
82 Water temperature sensor 83 Heating switch

Claims (5)

An exhaust heat recovery unit provided in an exhaust pipe near a differential case in which gear oil is enclosed, and capable of exchanging heat between the exhaust flowing through the exhaust pipe and the refrigerant;
A heat exchanger provided in the differential case and capable of exchanging heat between the gear oil and the refrigerant;
A heater core capable of exchanging heat between air and the refrigerant;
A blower fan that allows air to pass through the heater core in one direction;
A refrigerant passage connecting the exhaust heat recovery unit, the heat exchanger, and the heater core;
In a waste heat utilization system comprising: a pump that circulates the refrigerant in the refrigerant passage ,
When the temperature of the refrigerant is in a temperature range higher than a predetermined first predetermined value, the pump and the blower fan are driven, and outside air is passed through the heater core to exchange heat with the refrigerant. A control unit that executes a first mode for releasing outside air after heat exchange to the outside , and
An engine having the exhaust pipe is mounted in front of the vehicle;
The exhaust pipe runs under the floor of the vehicle toward the rear of the vehicle, and is arranged so that the downstream end of the exhaust pipe opens to the rear of the vehicle,
The differential case is disposed under the floor behind the vehicle,
When the output of the engine is transmitted to the rear wheel via a gear mechanism inside the differential case,
The exhaust heat recovery device, the heat exchanger, three of the heater core is characterized Rukoto arranged together in the rear of the vehicle exhaust heat utilization system.   The controller has a heating request for heating the room, and the temperature of the refrigerant falls within a temperature range lower than the first predetermined value and from a predetermined second predetermined value to the first predetermined value. At a certain time, the pump and the blower fan are driven, and a second mode is performed in which the inside air is passed through the heater core to exchange heat with the refrigerant, and the inside air after the heat exchange is returned to the room. The exhaust heat utilization system according to claim 1.   The control unit has no heating request for heating the room, and the temperature of the refrigerant is in a temperature range lower than the first predetermined value and from a predetermined second predetermined value to the first predetermined value. In a second mode, the pump is driven to stop the blower fan, and the inside air is passed through the heater core to exchange heat with the refrigerant, and the inside air after the heat exchange is returned to the room. The exhaust heat utilization system according to claim 1, wherein none of the first modes is executed. The control unit drives the pump to stop the blower fan when the refrigerant temperature is lower than the first predetermined value and in a temperature range lower than a predetermined second predetermined value, and 2. The second mode in which the inside air is passed through the heater core to exchange heat with the refrigerant, and the inside air after the heat exchange is returned to the room is not executed. The exhaust heat utilization system according to 1. An outside air chamber upstream of the heater core for introducing outside air;
An inside air room upstream of the heater core for introducing inside air,
When the drive signal is not received, it is at an intermediate position, and the outside air chamber and the heater core are communicated with a drive signal indicating the outside air side position, and the inside air room and the heater core are connected with a drive signal indicating the inside air side position. A first three-position valve in communication,
An outside air communication room that is downstream of the heater core and communicates with outside air,
An indoor communication room that is downstream of the heater core and communicates with the room,
When the drive signal is not received, the heater core is located at an intermediate position, and the air exiting the heater core with a drive signal indicating the outside air side position is introduced into the outside air communication room, and the heater core with a drive signal indicating the inside air side position. A second three-position valve for introducing the air that has exited into the indoor communication room,
An outside air selection mechanism having
When executing the first mode, the control unit issues a drive signal indicating an outside air side position to the two three-position valves, and when executing the second mode, the control unit outputs an internal air side to the two three-position valves. The exhaust heat utilization system according to claim 2 , wherein a drive signal indicating a position is issued.

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