Exhaust heat recovery device and air conditioner equipped with same

Abstract

To suppress degradation of fuel economy of an internal combustion engine, and furthermore to improve heating performance of an air-conditioning apparatus.SOLUTION: A second heat exchanger 60 capable of exchanging heat between exhaust gas 4 and lubrication oil 5, is connected to a main flow channel 33. A bypass flow channel 34 bypasses the second heat exchanger 60. A switching portion 35 switches by a control portion 80, a first state in which the exhaust gas 4 is guided to a portion comprising the second heat exchanger 60 of the main flow channel 33 and flow of the exhaust gas 4 to the bypass flow channel 34 is blocked and a second state in which the exhaust gas 4 is guided to the bypass flow channel 34 and flow of the exhaust gas 4 to a portion comprising the second heat exchanger 60 of the main flow channel 33 is blocked. In a heating operation of the air-conditioning apparatus 1, the switching portion 35 is switched to the second state by the control portion 80, the exhaust gas 4 and cooling water 6 exchange heat by a third heat exchanger 70, and a refrigerant 2 and the cooling water 6 exchange heat by a first heat exchanger 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an exhaust heat recovery device and an air conditioner equipped with the same. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2012-107599 (Patent Document 1) is a prior art document that discloses an exhaust heat recovery device. The exhaust heat recovery device described in Patent Document 1 includes a coolant flow path, a first exhaust gas flow path, and a lubricating oil flow path. Coolant for an internal combustion engine flows through the coolant flow path. Exhaust gas from the internal combustion engine flows through the first exhaust gas flow path. Lubricating oil for the internal combustion engine flows through the lubricating oil flow path. The lubricating oil flow path is provided so as to be able to exchange heat with the coolant flow path and the first exhaust gas flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-107599 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an air conditioner operated by an internal combustion engine, the internal combustion engine may be operated intermittently due to inverter control of the air conditioner. While the internal combustion engine is stopped, the cooling water flowing through the internal combustion engine releases heat and its temperature drops. In the exhaust heat recovery device described in Patent Document 1, heat is exchanged between the cooling water passage and the lubricating oil passage of the internal combustion engine, so that the temperature of the lubricating oil drops as the temperature of the cooling water drops. The drop in the lubricating oil temperature deteriorates the sliding characteristics of the sliding members of the internal combustion engine, and the fuel efficiency of the internal combustion engine drops. On the other hand, there is room to improve the heating performance of the air conditioner by exchanging heat between the cooling water and the refrigerant in the refrigerant cycle of the air conditioner.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide an exhaust heat recovery device and an air conditioning device equipped with the same, which can improve the heating performance of the air conditioning device while suppressing a decrease in fuel efficiency of the internal combustion engine. [Means for solving the problem]

[0006] The exhaust heat recovery device according to the present invention is provided in an internal combustion engine that drives a compressor of an air conditioner. The exhaust heat recovery device includes an exhaust gas flow path, a lubricating oil flow path, a cooling water flow path having a first heat exchanger, a second heat exchanger, a third heat exchanger, and a control unit. The exhaust gas flow path allows exhaust gas from the internal combustion engine to flow. The lubricating oil flow path circulates lubricating oil in the internal combustion engine. The cooling water flow path allows cooling water for cooling the internal combustion engine to flow. The first heat exchanger is capable of exchanging heat between the cooling water and a refrigerant that flows through a refrigerant cycle of the air conditioner. The second heat exchanger is connected to the exhaust gas flow path and the lubricating oil flow path, and is capable of exchanging heat between the exhaust gas and the lubricating oil. The third heat exchanger is connected to the exhaust gas flow path and the cooling water flow path, and exchanges heat between the exhaust gas and the cooling water. The exhaust gas flow path includes a main flow path, a bypass flow path, and a switching unit. The main flow path is connected to the second heat exchanger. The bypass flow path branches off from the main flow path upstream of the second heat exchanger and bypasses the second heat exchanger. The switching unit is switched by the control unit between a first state in which the exhaust gas is guided to a portion of the main flow path where the second heat exchanger is provided and the flow to the bypass flow path is blocked, and a second state in which the exhaust gas is guided to the bypass flow path and the flow to the portion of the main flow path where the second heat exchanger is provided is blocked. During heating operation of the air conditioner, the control unit switches the switching unit to the second state, and heat is exchanged between the exhaust gas and the coolant in the third heat exchanger, and heat is exchanged between the refrigerant and the coolant in the first heat exchanger.

[0007] In one embodiment of the present invention, the control unit controls the switching unit to switch to the first state when the temperature of the lubricant is lower than a predetermined temperature.

[0008] In one embodiment of the present invention, the main flow path is connected to the bypass flow path downstream of the second heat exchanger. The switching unit has a first switching unit provided upstream and a second switching unit provided downstream. In the first state, the bypass flow path is blocked by the first switching unit and the second switching unit.

[0009] An air conditioner according to the present invention includes the above-mentioned exhaust heat recovery device, a condenser, an expansion valve, and an evaporator. The condenser condenses the refrigerant compressed by the compressor. The expansion valve expands the refrigerant that has passed through the condenser. The evaporator vaporizes the refrigerant that has passed through the expansion valve and returns the vaporized refrigerant to the compressor. The refrigerant cycle is configured by circulating the refrigerant through the compressor, the condenser, the expansion valve, and the evaporator. The first heat exchanger is provided between the expansion valve and the evaporator in the refrigerant cycle. Effect of the Invention

[0010] According to the present invention, it is possible to improve the heating performance of an air conditioner while suppressing a decrease in fuel efficiency of an internal combustion engine. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of an air conditioning apparatus according to one embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing a configuration around a second heat exchanger included in an exhaust heat recovery device according to an embodiment of the present invention, in a first state of the second heat exchanger. [Diagram 3] 3 is a cross-sectional view of the second heat exchanger and its surrounding configuration as viewed from the direction of the arrows along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view showing a configuration around a second heat exchanger included in an exhaust heat recovery device according to one embodiment of the present invention, in a second state of the second heat exchanger. FIG. [Diagram 5] 4 is a graph showing temperature changes of the cooling water and the lubricating oil with respect to time in the exhaust heat recovery device according to the embodiment of the present invention. [Figure 6] 4 is a flowchart showing an operating state of an air conditioning apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an exhaust heat recovery device and an air conditioner including the same according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiment, the same or corresponding parts in the drawings are given the same reference numerals, and the description thereof will not be repeated.

[0013] Fig. 1 is a schematic diagram showing the configuration of an air conditioner according to an embodiment of the present invention. The air conditioner 1 according to an embodiment of the present invention is a gas heat pump (GHP) type air conditioner that performs air conditioning using a gas engine as an internal combustion engine as a drive source. Note that the internal combustion engine is not limited to a gas engine, and may be a gasoline engine, an LNG engine, an ethanol engine, or the like.

[0014] As shown in FIG. 1, the air conditioner 1 includes a compressor 10, a condenser 11, an expansion valve 12, an evaporator 13, a refrigerant passage 14, an internal combustion engine 20, a radiator 21, and an exhaust heat recovery device 3.

[0015] Compressor 10, condenser 11, expansion valve 12 and evaporator 13 are connected in this order by a refrigerant flow path 14, and refrigerant 2 circulates through these to form a refrigerant cycle.

[0016] The compressor 10 compresses the refrigerant 2. The refrigerant 2 is compressed into a high-temperature, high-pressure gas state. The condenser 11 condenses the refrigerant 2 compressed by the compressor 10. The refrigerant 2 exchanges heat with air by the condenser 11 and releases heat, thereby becoming a high-temperature, high-pressure liquid state. The expansion valve 12 expands the refrigerant 2 that has passed through the condenser 11. The refrigerant 2 is adiabatically expanded by the expansion valve 12 and becomes a low-temperature, low-pressure liquid state. The evaporator 13 vaporizes the refrigerant 2 that has passed through the expansion valve 12. The refrigerant 2 is exchanged heat with air by the evaporator 13 and absorbs heat, thereby becoming a low-temperature, low-pressure gas state. The refrigerant 2 vaporized by the evaporator 13 is returned to the compressor 10.

[0017] The refrigerant flow path 14 includes a first refrigerant flow path 14a, a second refrigerant flow path 14b, a third refrigerant flow path 14c, and a fourth refrigerant flow path 14d. The first refrigerant flow path 14a connects the compressor 10 and the condenser 11. The second refrigerant flow path 14b connects the condenser 11 and the expansion valve 12. The third refrigerant flow path 14c connects the expansion valve 12 and the evaporator 13. The fourth refrigerant flow path 14d connects the evaporator 13 and the compressor 10. As a result, when the refrigerant 2 circulates through the refrigerant flow path 14, the refrigerant 2 in the condenser 11 exchanges heat with the indoor air during heating operation. In addition, by switching the refrigerant path by a four-way valve (not shown), the condenser 11 becomes an evaporator during cooling operation, and the temperature of the indoor air is adjusted by heat exchange between the refrigerant 2 inside and the indoor air.

[0018] A first heat exchanger 15 is provided in a third refrigerant flow path 14c between the expansion valve 12 and the evaporator 13 in the refrigerant cycle. The first heat exchanger 15 is capable of exchanging heat between the coolant 6 in a coolant flow path 50 (described later) and the refrigerant 2 flowing through the refrigerant cycle of the air conditioner 1.

[0019] The internal combustion engine 20 drives the compressor 10 of the air conditioner 1. The internal combustion engine 20 is connected to the compressor 10 by a pulley or the like (not shown), and drives the compressor 10.

[0020] The radiator 21 cools the internal combustion engine 20. The radiator 21 is connected to the internal combustion engine 20 by a coolant passage 50, which will be described later. The radiator 21 is air-cooled or water-cooled by a heat exchange medium 22, such as air or coolant.

[0021] The exhaust heat recovery device 3 is provided in the internal combustion engine 20 and recovers heat from the exhaust gas 4. The exhaust heat recovery device 3 includes an exhaust gas passage 30, a lubricant oil passage 40, a coolant passage 50, a second heat exchanger 60, and a third heat exchanger 70.

[0022] Exhaust gas 4 from the internal combustion engine 20 flows through the exhaust gas passage 30. The exhaust gas 4 from the internal combustion engine 20 flows through the exhaust gas passage 30 and is discharged from an exhaust port 31 to the outside.

[0023] The exhaust gas flow path 30 has a main flow path 33, a bypass flow path 34, and a switching section 35. The exhaust gas 4 can flow through the main flow path 33 or the bypass flow path 34. The flow path of the exhaust gas 4 is switched by the switching section 35. The configurations of the main flow path 33, the bypass flow path 34, and the switching section 35 will be described later.

[0024] Lubricating oil 5 circulates through the lubricating oil flow path 40 in the internal combustion engine 20. The lubricating oil 5 improves the sliding characteristics of sliding members such as a cylinder or a piston (not shown) in the internal combustion engine 20. Since the viscosity of the lubricating oil 5 increases as the temperature of the lubricating oil 5 decreases, the sliding characteristics of the sliding members deteriorate as the temperature of the lubricating oil 5 decreases.

[0025] The coolant 6 for cooling the internal combustion engine 20 flows through the coolant flow passage 50. The coolant flow passage 50 includes a first coolant flow passage 51, a second coolant flow passage 53, and a third coolant flow passage 55.

[0026] The first coolant flow path 51 introduces the coolant 6 into the internal combustion engine 20. A first valve 52 is provided in the first coolant flow path 51 midway through the flow path. The first valve 52 is, for example, a three-way valve. The first valve 52 switches the flow path of the coolant 6 flowing into the first coolant flow path 51 from either the radiator 21 or the third coolant flow path 55.

[0027] The coolant 6 that has cooled the internal combustion engine 20 flows through the second coolant flow path 53. A second valve 54 is provided in the second coolant flow path 53. The second valve 54 is, for example, a three-way valve. The second valve 54 switches the flow path of the coolant 6 that flows from the second coolant flow path 53 to either the radiator 21 or the third coolant flow path 55.

[0028] The third coolant flow path 55 branches off from the first coolant flow path 51 and the second coolant flow path 53. The coolant 6 flows through the third coolant flow path 55. The first heat exchanger 15 is disposed on the third coolant flow path 55. The first heat exchanger 15 is capable of exchanging heat between the coolant 6 flowing through the third coolant flow path 55 and the refrigerant 2 in the refrigerant cycle.

[0029] The second heat exchanger 60 is connected to the exhaust gas passage 30 and the lubricant oil passage 40 and is capable of exchanging heat between the exhaust gas 4 and the lubricant oil 5 .

[0030] The third heat exchanger 70 is connected to the exhaust gas passage 30 and the cooling water passage 50, and exchanges heat between the exhaust gas 4 and the cooling water 6.

[0031] In addition, in this embodiment, the second heat exchanger 60 is located upstream of the third heat exchanger 70 in the exhaust gas flow path 30, but the second heat exchanger 60 may be located downstream of the third heat exchanger 70 in the exhaust gas flow path 30.

[0032] The control unit 80 can control the switching unit 35 by a signal from the internal combustion engine 20. The control unit 80 is connected to the internal combustion engine 20 and the second heat exchanger 60 by wire or wirelessly so as to be able to transmit and receive the signal.

[0033] Hereinafter, heat exchange between the exhaust gas 4 and the lubricating oil 5 in the second heat exchanger 60 in the exhaust gas passage 30 will be described.

[0034] Fig. 2 is a cross-sectional view showing the configuration of the second heat exchanger and its periphery in a first state of the exhaust heat recovery device according to an embodiment of the present invention. Fig. 3 is a cross-sectional view showing the configuration of the second heat exchanger and its periphery in Fig. 2 as viewed from the direction of the arrows III-III line. Fig. 4 is a cross-sectional view showing the configuration of the second heat exchanger and its periphery in a second state of the exhaust heat recovery device according to an embodiment of the present invention.

[0035] As shown in Figs. 2 to 4, the exhaust gas flow path 30 in this embodiment is formed inside the gas piping 32. The exhaust gas 4 flows inside the gas piping 32. The main flow path 33 constitutes a part of the gas piping 32. The main flow path 33 is connected to a second heat exchanger 60.

[0036] The lubricant oil passage 40 is formed inside the lubricant oil pipe 41. The lubricant oil 5 flows inside the lubricant oil pipe 41. The second heat exchanger 60 is formed by connecting a part of the gas pipe 32 constituting the main passage 33 to the lubricant oil pipe 41. The second heat exchanger 60 in this embodiment is formed by covering the outer circumferential surface of a part of the gas pipe 32 constituting the main passage 33 with the lubricant oil pipe 41.

[0037] The bypass flow passage 34 branches off from the main flow passage 33 upstream of the second heat exchanger 60. The bypass flow passage 34 bypasses the second heat exchanger 60. That is, when the exhaust gas 4 flows through the bypass flow passage 34, heat exchange does not occur between the exhaust gas 4 and the lubricating oil 5.

[0038] The bypass flow passage 34 is connected to the main flow passage 33 downstream of the second heat exchanger 60. Note that the bypass flow passage 34 may extend to the exhaust port 31 without being connected to the main flow passage 33 downstream of the second heat exchanger 60.

[0039] The switching unit 35 is switched between a first state and a second state under the control of the control unit 80. The first state is a state in which the exhaust gas 4 is guided to a portion of the main flow path 33 where the second heat exchanger 60 is provided, and the flow to the bypass flow path 34 is blocked. The second state is a state in which the exhaust gas 4 is guided to the bypass flow path 34, and the flow to the portion of the main flow path 33 where the second heat exchanger is provided is blocked. The switching unit 35 is, for example, a solenoid valve.

[0040] The switching unit 35 in this embodiment has a first switching unit 35a and a second switching unit 35b. The first switching unit 35a is provided upstream of the second heat exchanger 60 in the exhaust gas flow path 30. The second switching unit 35b is provided downstream of the second heat exchanger 60.

[0041] 2, in the first state, the bypass flow path 34 is blocked by the first switching unit 35a and the second switching unit 35b. This causes heat exchange between the exhaust gas 4 and the lubricating oil 5 in the second heat exchanger 60. Note that, although the switching unit 35 according to the present embodiment is configured by the first switching unit 35a and the second switching unit 35b, the present invention is not limited to this configuration, and may be configured to include only the first switching unit 35a.

[0042] 4, in the second state, the portion of the main flow passage 33 where the second heat exchanger 60 is provided is blocked by the first switching unit 35a and the second switching unit 35b. As a result, the exhaust gas 4 flows through the bypass flow passage 34 without being subjected to heat exchange with the lubricating oil 5 in the second heat exchanger 60.

[0043] It is preferable that the first switching unit 35a and the second switching unit 35b perform the switching operation simultaneously. This makes it possible to suppress unintended inflow of the exhaust gas 4 on the upstream side or reverse flow on the downstream side of the flow path blocked by the switching operation of the switching unit 35.

[0044] Fig. 5 is a graph showing the temperature changes of the coolant and lubricant over time in an exhaust heat recovery device according to an embodiment of the present invention. In Fig. 5, the vertical axis shows temperature (°C) and the horizontal axis shows time (t). On the horizontal axis in Fig. 5, time t0 shows the start time of the internal combustion engine, time t1 shows the stop time of the internal combustion engine, time t2 shows the time when the circulation of the coolant is stopped, and time t3 shows the restart time of the internal combustion engine.

[0045] As shown in Fig. 5, when the internal combustion engine starts (t0), the temperature of the lubricating oil and the cooling water rises due to heat exchange between the exhaust gas of the internal combustion engine and the lubricating oil and the cooling water. Since the degree of heat exchange with the indoor air is adjusted by inverter control, the internal combustion engine stops after a certain time has passed after the internal combustion engine starts (t0) (t1).

[0046] The coolant circulates in the coolant flow passage for a certain period of time even when the internal combustion engine is stopped. As a result, the coolant undergoes heat exchange in the radiator, lowering the temperature of the coolant. After a certain period of time has passed, the circulation of the coolant is stopped (t2). During the period from when the circulation of the coolant stops (t2) until the internal combustion engine is restarted (t3), the lubricating oil and the coolant are naturally cooled. When the internal combustion engine is restarted (t3) in conjunction with the start of the air conditioning unit by inverter control, heat is exchanged again between the exhaust gas and the coolant and lubricating oil, causing the coolant temperature and the lubricating oil temperature to rise.

[0047] As shown by the dotted line of the lubricant temperature in Fig. 5, when the coolant and the lubricant are simultaneously heat-exchanged by the exhaust gas in the exhaust heat recovery device, the lubricant temperature is affected by the coolant temperature and decreases after the internal combustion engine is stopped (t1). This deteriorates the sliding characteristics of the sliding members in the internal combustion engine. As a result, the fuel efficiency of the internal combustion engine decreases.

[0048] On the other hand, as shown by the solid line of the lubricating oil temperature in Fig. 5, in the exhaust heat recovery device 3 of this embodiment, the lubricating oil 5 and the coolant 6 are not simultaneously heat exchanged by the exhaust gas 4, so that even if the temperature of the coolant 6 drops after the internal combustion engine 20 is stopped (t2), the temperature drop of the lubricating oil 5 is suppressed. This suppresses an increase in the viscosity of the lubricating oil 5, thereby maintaining the sliding characteristics of the sliding members in the internal combustion engine 20. As a result, a decrease in the fuel efficiency of the internal combustion engine 20 is suppressed.

[0049] FIG. 6 is a flowchart showing the operating state of an air conditioner according to one embodiment of the present invention.

[0050] As shown in Figs. 1, 2, 4 and 6, in the air conditioner 1 of this embodiment, the control of the exhaust heat recovery device 3 differs between during heating operation and during cooling operation.

[0051] Specifically, first, it is confirmed that the internal combustion engine 20 is in operation. When the internal combustion engine 20 is in operation, a temperature sensor (not shown) in the internal combustion engine 20 starts monitoring the lubricant temperature and the coolant temperature. When the internal combustion engine 20 is not in operation, there is no need for heat exchange between the exhaust gas 4 and the lubricant 5. For this reason, the switching unit 35 is switched by the control of the control unit 80 to a second state in which the exhaust gas 4 is guided to the bypass flow path 34 and the flow to the portion of the main flow path 33 where the second heat exchanger 60 is provided is blocked.

[0052] Next, it is confirmed that the air conditioner 1 is in heating operation. If it is in heating operation, the switching unit 35 is switched to the above-mentioned second state under the control of the control unit 80.

[0053] When the air conditioner 1 is not in heating operation, the control unit 80 confirms that the lubricating oil temperature is lower than a predetermined temperature. The control unit 80 in this embodiment confirms that the lubricating oil temperature is lower than a predetermined temperature by receiving a signal that directly measures the lubricating oil temperature in the internal combustion engine 20. The predetermined temperature in this embodiment is, for example, 100 to 110°C.

[0054] Next, the control unit 80 controls the switching unit 35 to switch to the first state in which the exhaust gas 4 is guided to the portion of the main flow path 33 where the second heat exchanger 60 is provided and the flow to the bypass flow path 34 is blocked when the temperature of the lubricating oil 5 is lower than a predetermined temperature. On the other hand, when the temperature of the lubricating oil is higher than the predetermined temperature, the switching unit 35 is switched to the second state under the control of the control unit 80.

[0055] By the above-mentioned control, during heating operation of the air conditioner 1, the control unit 80 switches the switching unit 35 to the second state, and heat is exchanged between the exhaust gas 4 and the coolant 6 in the third heat exchanger 70, and heat is exchanged between the refrigerant 2 and the coolant 6 in the first heat exchanger 15. As a result, by stopping the heat exchange between the exhaust gas 4 and the lubricating oil 5 in the exhaust heat recovery device 3, the heat of the exhaust gas 4 can be exchanged with the coolant 6 in the first heat exchanger 15 without being used to increase the temperature of the lubricating oil 5. As a result, more heat of the exhaust gas 4 can be used for the heat input of the refrigerant 2 to assist the function of the evaporator 13, and the heating performance of the air conditioner 1 can be improved.

[0056] In the exhaust heat recovery device 3 according to one embodiment of the present invention, aside from the heat exchange between the exhaust gas 4 and the coolant 6, the second heat exchanger 60 is configured to be able to exchange heat between the exhaust gas 4 and the lubricating oil 5, thereby making it possible to suppress a decrease in temperature of the lubricating oil 5 in the internal combustion engine 20. As a result, an increase in the viscosity of the lubricating oil 5 is suppressed, and the sliding characteristics of the sliding members in the internal combustion engine 20 are maintained, making it possible to suppress a decrease in fuel efficiency of the internal combustion engine 20.

[0057] Furthermore, in the exhaust heat recovery device 3 according to one embodiment of the present invention, during heating operation of the air conditioner 1, the exhaust gas 4 and the coolant 6 are heat exchanged in the third heat exchanger 70 without heat exchange between the exhaust gas 4 and the lubricating oil 5 in the second heat exchanger 60, thereby making it possible to exchange heat between the coolant 6 and the refrigerant 2 in the refrigerant cycle in the first heat exchanger 15. Therefore, during heating operation, the heat of the exhaust gas 4 is not used to raise the temperature of the lubricating oil 5, but is instead exchanged with the coolant 6 in the first heat exchanger 15, and more of the heat of the exhaust gas 4 can be used to input heat to the refrigerant 2 to assist the function of the evaporator 13, thereby improving the heating performance of the air conditioner 1.

[0058] In an exhaust heat recovery device 3 according to one embodiment of the present invention, a predetermined temperature is set and the temperature of the lubricating oil 5 is directly monitored, so that efficient switching operation can be performed in the switching unit 35 by sending a signal from the control unit 80 to the switching unit 35 on the exhaust gas flow path 30 when the temperature of the lubricating oil 5 is below the predetermined temperature.

[0059] In the exhaust heat recovery device 3 according to one embodiment of the present invention, by providing the second switching unit 35b, it is possible to prevent the exhaust gas 4 from flowing back into the main flow path 33, thereby reliably blocking the main flow path 33. This reliably suppresses heat exchange between the exhaust gas 4 and the lubricating oil 5 during heating operation of the air conditioner 1, and allows the exhaust gas 4 to exchange heat with the cooling water 6 related to improving heating performance.

[0060] In the air conditioner 1 according to one embodiment of the present invention, the first heat exchanger 15 is provided between the expansion valve 12 and the evaporator 13 in the refrigerant cycle, so that during heating operation, the coolant 6 and the refrigerant 2 exchange heat in the first heat exchanger 15, causing the temperature of the refrigerant 2 to rise. This allows the heat of the exhaust gas 4 in the exhaust heat recovery device 3 to be exchanged with the coolant 6 in the first heat exchanger 15 without being used to raise the temperature of the lubricating oil 5. As a result, more of the heat of the exhaust gas 4 can be used to input heat to the refrigerant 2 to assist the function of the evaporator 13, thereby improving the heating performance.

[0061] An exhaust heat recovery device according to a modified example of an embodiment of the present invention and an air conditioner equipped with the same will be described below. The exhaust heat recovery device according to this modified example and the air conditioner equipped with the same have a different control method for the control unit from the exhaust heat recovery device 3 according to embodiment 1 of the present invention and the air conditioner 1 equipped with the same, so the description of the configuration that is similar to the exhaust heat recovery device 3 according to embodiment 1 of the present invention and the air conditioner 1 equipped with the same will not be repeated.

[0062] The control unit included in the exhaust heat recovery device according to the modified example of the embodiment of the present invention can control the second heat exchanger by a signal from the internal combustion engine, etc. Specifically, the control unit estimates the temperature of the lubricating oil from the rotation speed, load, operating time or coolant temperature of the internal combustion engine, or the outside air temperature, etc. In this way, the control unit confirms that the lubricating oil temperature is lower than a predetermined temperature.

[0063] In an exhaust heat recovery device according to a modified example of an embodiment of the present invention and an air conditioner equipped with the same, a control unit estimates the temperature of the lubricating oil based on a signal from an internal combustion engine or the like, and a second heat exchanger is configured to enable heat exchange between the exhaust gas and the lubricating oil, thereby suppressing a decrease in the temperature of the lubricating oil in the internal combustion engine. This suppresses an increase in the viscosity of the lubricating oil, and maintains the sliding characteristics of the sliding members in the internal combustion engine, thereby suppressing a decrease in the fuel efficiency of the internal combustion engine.

[0064] Furthermore, in the exhaust heat recovery device according to a modified example of an embodiment of the present invention and an air conditioning device equipped with the same, as in the embodiment of the present invention, during heating operation of the air conditioning device, the heat of the exhaust gas is not used to raise the temperature of the lubricating oil, but is instead exchanged with the cooling water in the first heat exchanger, and can be used to input heat to the refrigerant to assist the function of the evaporator, thereby improving the heating performance of the air conditioning device.

[0065] It should be noted that the above-mentioned embodiments disclosed herein are illustrative in all respects and are not intended to be a basis for restrictive interpretation. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-mentioned embodiments. Furthermore, all modifications within the meaning and scope equivalent to the claims are included. In the above-mentioned description of the embodiments, configurations that can be combined may be combined with each other. [Explanation of symbols]

[0066] REFERENCE SIGNS LIST 1 air conditioner, 2 refrigerant, 3 exhaust heat recovery device, 4 exhaust gas, 5 lubricating oil, 6 cooling water, 10 compressor, 11 condenser, 12 expansion valve, 13 evaporator, 14 refrigerant flow path, 14a first refrigerant flow path, 14b second refrigerant flow path, 14c third refrigerant flow path, 14d fourth refrigerant flow path, 15 first heat exchanger, 20 internal combustion engine, 21 radiator, 22 heat exchange medium, 30 exhaust gas flow path, 31 exhaust port, 32 gas piping, 33 main flow path, 34 bypass flow path, 35 switching unit, 35a first switching unit, 35b second switching unit, 40 lubricating oil flow path, 41 lubricating oil piping, 50 cooling water flow path, 51 first cooling water flow path, 52 first valve, 53 second cooling water flow path, 54 second valve, 55 third cooling water flow path, 60 second heat exchanger, 70 Third heat exchanger, 80 control section.

Claims

1. An exhaust heat recovery device provided in an internal combustion engine that drives a compressor of an air conditioning device, an exhaust gas flow path through which exhaust gas from the internal combustion engine flows; a lubricating oil flow path for circulating lubricating oil in the internal combustion engine; a cooling water flow path having a first heat exchanger through which cooling water for cooling the internal combustion engine flows and capable of exchanging heat between the cooling water and a refrigerant flowing through a refrigerant cycle of the air conditioning device; a second heat exchanger connected to the exhaust gas passage and the lubricating oil passage and capable of exchanging heat between the exhaust gas and the lubricating oil; a third heat exchanger connected to the exhaust gas passage and the cooling water passage, for exchanging heat between the exhaust gas and the cooling water; A control unit. The exhaust gas flow path is A main flow path to which the second heat exchanger is connected; a bypass flow path that branches off from the main flow path upstream of the second heat exchanger and bypasses the second heat exchanger; a switching unit that switches between a first state in which the exhaust gas is guided to a portion of the main flow path where the second heat exchanger is provided and the flow to the bypass flow path is blocked, and a second state in which the exhaust gas is guided to the bypass flow path and the flow to the portion of the main flow path where the second heat exchanger is provided, An exhaust heat recovery device in which, during heating operation of the air conditioning apparatus, the control unit switches the switching unit to the second state, heat is exchanged between exhaust gas and cooling water in the third heat exchanger, and heat is exchanged between refrigerant and cooling water in the first heat exchanger.

2. The exhaust heat recovery device according to claim 1 , wherein the control unit controls the switching unit to switch to the first state when a temperature of the lubricating oil is lower than a predetermined temperature.

3. The main flow path is connected to the bypass flow path downstream of the second heat exchanger, The switching unit has a first switching unit provided on the upstream side and a second switching unit provided on the downstream side, The exhaust heat recovery device according to claim 1 or 2, wherein in the first state, the bypass passage is blocked by the first switching unit and the second switching unit.

4. The exhaust heat recovery device according to claim 1 ; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve for expanding the refrigerant that has passed through the condenser; a evaporator that vaporizes the refrigerant that has passed through the expansion valve and returns the vaporized refrigerant to the compressor; the refrigeration cycle is configured by circulating a refrigerant through the compressor, the condenser, the expansion valve, and the evaporator, The air-conditioning apparatus, wherein the first heat exchanger is provided between the expansion valve and the evaporator in the refrigerant cycle.

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