JP2023140441A - Waste heat recovery equipment and air-conditioning apparatus with the same - Google Patents

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

The present invention relates to an exhaust heat recovery device and an air conditioner equipped with the same.

As a prior art document disclosing an exhaust heat recovery device, there is JP-A-2012-107599 (Patent Document 1). The exhaust heat recovery device described in Patent Document 1 includes a cooling water flow path, a first exhaust gas flow path, and a lubricating oil flow path. Cooling water for the internal combustion engine flows through the cooling water flow path. Exhaust gas from the internal combustion engine flows through the first exhaust gas flow path. The lubricant oil for the internal combustion engine flows through the lubricant flow path. The lubricating oil flow path is provided so as to be able to exchange heat with the cooling water flow path and the first exhaust gas flow path.

Japanese Patent Application Publication No. 2012-107599

In an air conditioner operated by an internal combustion engine, the internal combustion engine may operate 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 radiates heat and its temperature decreases. In the exhaust heat recovery device described in Patent Document 1, heat is exchanged between the cooling water flow path of the internal combustion engine and the lubricating oil flow path, so that the temperature of the lubricating oil decreases as the temperature of the cooling water decreases. As the lubricating oil temperature decreases, the sliding characteristics of the sliding members of the internal combustion engine deteriorate, resulting in a decrease in the fuel efficiency of the internal combustion engine. 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.

The present invention has been made to solve the above problems, and includes an exhaust heat recovery device and an exhaust heat recovery device that can improve the heating performance of an air conditioner while suppressing a decrease in fuel efficiency of an internal combustion engine. The purpose of the present invention is to provide an air conditioner equipped with the following.

The exhaust heat recovery device based on 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 section. Exhaust gas from the internal combustion engine flows through the exhaust gas flow path. The lubricating oil flow path circulates lubricating oil to the internal combustion engine. The cooling water flow path allows cooling water to cool the internal combustion engine to flow therethrough. The first heat exchanger is capable of exchanging heat between the cooling water and the refrigerant flowing through the 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 section. A second heat exchanger is connected to the main flow path. The bypass flow path branches from the main flow path on the upstream side of the second heat exchanger and bypasses the second heat exchanger. The switching unit is controlled by the control unit to switch 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 a flow to the bypass flow path is cut off, and a first state in which the exhaust gas is guided to the bypass flow path and the flow to the main flow path is interrupted. and a second state in which the flow to the portion where the second heat exchanger is provided is cut off. During heating operation of the air conditioner, the control unit switches the switching unit to the second state, and the exhaust gas and cooling water exchange heat in the third heat exchanger, and the cooling water and the refrigerant exchange in the first heat exchanger. Heat is exchanged with water.

In one form of the present invention, the control unit controls the switching unit to switch to the first state when the temperature of the lubricating oil is lower than a predetermined temperature.

In one form of the present invention, the main flow path is connected to the bypass flow path downstream of the second heat exchanger. The switching section includes a first switching section provided on the upstream side and a second switching section provided on the downstream side. In the first state, the bypass flow path is blocked by the first switching section and the second switching section.

An air conditioner based on the present invention includes the above-mentioned exhaust heat recovery device, a condenser, an expansion valve, and a vaporizer. The condenser condenses the refrigerant compressed by the compressor. The expansion valve expands the refrigerant that has passed through the condenser. The vaporizer vaporizes the refrigerant that has passed through the expansion valve and returns the vaporized refrigerant to the compressor. A refrigerant cycle consists of a refrigerant circulating through a compressor, a condenser, an expansion valve, and a vaporizer. The first heat exchanger is provided between the expansion valve and the vaporizer in the refrigerant cycle.

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.

1 is a schematic diagram showing the configuration of an air conditioner according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing the configuration around the second heat exchanger in a first state of the second heat exchanger included in the exhaust heat recovery device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of the configuration around the second heat exchanger in FIG. 2, viewed from the direction of the arrow III-III. FIG. 3 is a cross-sectional view showing the configuration around the second heat exchanger in a second state of the second heat exchanger included in the exhaust heat recovery device according to the embodiment of the present invention. 3 is a graph showing temperature changes of cooling water and lubricating oil with respect to time in the exhaust heat recovery device according to an embodiment of the present invention. 1 is a flowchart showing the operating state of an air conditioner according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust heat recovery device and an air conditioner equipped with the same according to an embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the figures are denoted by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a schematic diagram showing the configuration of an air conditioner according to an embodiment of the present invention. An 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 driving 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.

As shown in FIG. 1, the air conditioner 1 includes a compressor 10, a condenser 11, an expansion valve 12, a vaporizer 13, a refrigerant flow path 14, an internal combustion engine 20, a radiator 21, and an exhaust heat recovery system. and a device 3.

The compressor 10, the condenser 11, the expansion valve 12, and the vaporizer 13 are connected in this order by a refrigerant flow path 14, and the refrigerant 2 circulates through these to form a refrigerant cycle.

Compressor 10 compresses refrigerant 2. By being compressed, the refrigerant 2 becomes 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 in the condenser 11 and radiates 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 liquid state at a low temperature and low pressure. The vaporizer 13 vaporizes the refrigerant 2 that has passed through the expansion valve 12 . The refrigerant 2 exchanges heat with the air in the vaporizer 13 and absorbs heat, thereby becoming a low-temperature, low-pressure gas state. The refrigerant 2 vaporized by the vaporizer 13 is returned to the compressor 10.

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 vaporizer 13. The fourth refrigerant flow path 14d connects the vaporizer 13 and the compressor 10. Thereby, when the refrigerant 2 circulates through the refrigerant flow path 14, heat is exchanged between the refrigerant 2 of the condenser 11 and indoor air during heating operation. Furthermore, by switching the refrigerant path using a four-way valve (not shown), the condenser 11 becomes a vaporizer during cooling operation, and the temperature of the indoor air is adjusted by exchanging heat between the internal refrigerant 2 and indoor air.

A first heat exchanger 15 is provided in the third refrigerant flow path 14c between the expansion valve 12 and the vaporizer 13 in the refrigerant cycle. The first heat exchanger 15 is capable of exchanging heat between the cooling water 6 in a cooling water flow path 50, which will be described later, and the refrigerant 2 flowing through the refrigerant cycle of the air conditioner 1.

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

Radiator 21 cools internal combustion engine 20 . The radiator 21 is connected to the internal combustion engine 20 through a cooling water flow path 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 cooling water.

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 flow path 30, a lubricating oil flow path 40, a cooling water flow path 50, a second heat exchanger 60, and a third heat exchanger 70.

Exhaust gas 4 from the internal combustion engine 20 flows through the exhaust gas flow path 30 . Exhaust gas 4 from internal combustion engine 20 flows through exhaust gas flow path 30 and is discharged to the outside from exhaust port 31 .

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, bypass flow path 34, and switching section 35 will be described later.

Lubricating oil 5 circulates in the internal combustion engine 20 through the lubricating oil flow path 40 . The lubricating oil 5 improves the sliding characteristics of a sliding member 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 its temperature decreases, the sliding characteristics of the sliding member deteriorate as the temperature of the lubricating oil 5 decreases.

Cooling water 6 that cools the internal combustion engine 20 flows through the cooling water flow path 50 . The cooling water passage 50 includes a first cooling water passage 51 , a second cooling water passage 53 , and a third cooling water passage 55 .

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 cooling water flow path 51 in the middle of the flow path. The first valve 52 is, for example, a three-way valve. The first valve 52 switches the flow path of the cooling water 6 flowing into the first cooling water flow path 51 from either the radiator 21 or the third cooling water flow path 55 .

Cooling water 6 after cooling the internal combustion engine 20 flows through the second cooling water flow path 53 . A second valve 54 is provided in the second cooling water flow path 53 in the middle of the flow path. The second valve 54 is, for example, a three-way valve. The second valve 54 switches the flow path of the cooling water 6 flowing from the second cooling water flow path 53 into either the radiator 21 or the third cooling water flow path 55 .

The third cooling water passage 55 branches from the first cooling water passage 51 and the second cooling water passage 53. Cooling water 6 flows through the third cooling water flow path 55 . The first heat exchanger 15 is arranged on the third cooling water flow path 55. The first heat exchanger 15 is capable of exchanging heat between the cooling water 6 flowing through the third cooling water flow path 55 and the refrigerant 2 in the refrigerant cycle.

The second heat exchanger 60 is connected to the exhaust gas passage 30 and the lubricating oil passage 40, and is capable of exchanging heat between the exhaust gas 4 and the lubricating oil 5.

The third heat exchanger 70 is connected to the exhaust gas flow path 30 and the cooling water flow path 50, and allows heat exchange between the exhaust gas 4 and the cooling water 6.

Note that the second heat exchanger 60 in this embodiment is located upstream of the third heat exchanger 70 in the exhaust gas flow path 30; It may be located downstream of the third heat exchanger 70.

The control unit 80 can control the switching unit 35 based on 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 that the signals can be transmitted and received.

Hereinafter, heat exchange between the exhaust gas 4 and the lubricating oil 5 in the second heat exchanger 60 on the exhaust gas flow path 30 will be described.

FIG. 2 is a sectional view showing the configuration around the second heat exchanger in the first state of the second heat exchanger included in the exhaust heat recovery apparatus according to the embodiment of the present invention. FIG. 3 is a sectional view of the configuration around the second heat exchanger in FIG. 2, viewed from the direction of the arrow III-III. FIG. 4 is a sectional view showing the configuration around the second heat exchanger in the second state of the second heat exchanger included in the exhaust heat recovery apparatus according to the embodiment of the present invention.

As shown in FIGS. 2 to 4, the exhaust gas passage 30 in this embodiment is formed inside a gas pipe 32. As shown in FIGS. The exhaust gas 4 flows inside the gas pipe 32. The main flow path 33 constitutes a part of the gas pipe 32. Main flow path 33 is connected to second heat exchanger 60 .

The lubricating oil flow path 40 is formed inside the lubricating oil piping 41. The lubricating oil 5 flows inside the lubricating oil piping 41 . The second heat exchanger 60 is configured by connecting a part of the gas pipe 32 that constitutes the main flow path 33 and the lubricating oil pipe 41. The second heat exchanger 60 in this embodiment is configured by covering the outer peripheral surface of a part of the gas pipe 32 constituting the main flow path 33 with a lubricating oil pipe 41.

The bypass flow path 34 branches from the main flow path 33 on the upstream side of the second heat exchanger 60. Bypass flow path 34 bypasses second heat exchanger 60 . That is, when the exhaust gas 4 flows through the bypass passage 34, heat exchange is not performed between the exhaust gas 4 and the lubricating oil 5.

The bypass flow path 34 is connected to the main flow path 33 on the downstream side of the second heat exchanger 60 . Note that the bypass flow path 34 may extend to the exhaust port 31 without being connected to the main flow path 33 on the downstream side of the second heat exchanger 60.

The switching unit 35 is switched to the first state or the 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.

The switching section 35 in this embodiment includes a first switching section 35a and a second switching section 35b. The first switching section 35a is provided upstream of the second heat exchanger 60 in the exhaust gas flow path 30. The second switching section 35b is provided downstream from the second heat exchanger 60.

As shown in FIG. 2, in the first state, the bypass flow path 34 is blocked by the first switching section 35a and the second switching section 35b. Thereby, heat is exchanged 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 includes a first switching unit 35a and a second switching unit 35b, it is not limited to this configuration, and may include a configuration in which only the first switching unit 35a is provided. There may be.

As shown in FIG. 4, in the second state, the portion of the main flow path 33 where the second heat exchanger 60 is provided is blocked by the first switching section 35a and the second switching section 35b. As a result, the exhaust gas 4 flows through the bypass passage 34 without being heat exchanged with the lubricating oil 5 in the second heat exchanger 60.

Note that it is desirable that the first switching section 35a and the second switching section 35b perform switching operations at the same time. Thereby, it is possible to suppress unintended inflow of exhaust gas 4 on the upstream side or backflow on the downstream side with respect to the flow path that is blocked by the switching operation of the switching unit 35.

FIG. 5 is a graph showing temperature changes of cooling water and lubricating oil with respect to time in the 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 indicates the start time of the internal combustion engine, time t1 indicates the stop time of the internal combustion engine, time t2 indicates the time when the circulation of cooling water is stopped, and time t3 indicates the restart time of the internal combustion engine.

As shown in FIG. 5, when the internal combustion engine starts (t0), the exhaust gas of the internal combustion engine and the lubricating oil and cooling water exchange heat, so that the temperatures of the lubricating oil and the cooling water rise. In the air conditioner, the degree of heat exchange with indoor air is adjusted by inverter control, so after the internal combustion engine is started (t0), the internal combustion engine is stopped (t1) after a certain period of time has elapsed.

The cooling water circulates within the cooling water flow path for a certain period of time even when the internal combustion engine is stopped. As a result, the cooling water undergoes heat exchange in the radiator, and the temperature of the cooling water decreases. After a certain period of time has elapsed, the circulation of the cooling water is stopped (t2). During the period from when the circulation of the cooling water stops (t2) to when the internal combustion engine restarts (t3), the lubricating oil and the cooling water are naturally cooled. When the internal combustion engine is restarted by the inverter control as the air conditioner is started (t3), heat is exchanged between the exhaust gas, the cooling water, and the lubricating oil again, so that the cooling water temperature and the lubricating oil temperature rise.

As shown by the lubricating oil temperature indicated by the dotted line in Figure 5, when cooling water and lubricating oil are simultaneously heat exchanged by exhaust gas in the exhaust heat recovery device, the lubricating oil temperature is affected by the cooling water temperature. , decreases after the internal combustion engine stops (t1). This deteriorates the sliding characteristics of the sliding member in the internal combustion engine. As a result, the fuel efficiency of the internal combustion engine decreases.

On the other hand, as shown by the lubricating oil temperature indicated by the solid line in FIG. Even if the temperature of the cooling water 6 decreases after the stop (t2) of the lubricating oil 5, the decrease in the temperature 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 member in the internal combustion engine 20. As a result, a decrease in fuel efficiency of the internal combustion engine 20 is suppressed.

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

As shown in FIGS. 1, 2, 4, and 6, in the air conditioner 1 according to the present embodiment, the control of the exhaust heat recovery device 3 is different between heating operation and cooling operation.

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 lubricating oil temperature and the cooling water 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 lubricating oil 5. Therefore, under the control of the control unit 80, the switching unit 35 enters the second state in which the exhaust gas 4 is guided to the bypass passage 34 and the flow to the part of the main passage 33 where the second heat exchanger 60 is provided is cut off. Can be switched.

Next, confirm that the air conditioner 1 is in heating operation. In the case of heating operation, the switching section 35 is switched to the second state under the control of the control section 80.

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 of 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.

Next, when the temperature of the lubricating oil 5 is lower than a predetermined temperature, the control unit 80 guides the exhaust gas 4 to a portion of the main flow path 33 where the second heat exchanger 60 is provided and blocks the flow to the bypass flow path 34. The switching unit 35 is controlled to switch to the first state. On the other hand, when the lubricating oil temperature is higher than the predetermined temperature, the switching section 35 is switched to the second state under the control of the control section 80.

Through the above-described control, during the heating operation of the air conditioner 1, the control unit 80 switches the switching unit 35 to the second state, and the exhaust gas 4 and the cooling water 6 are heated in the third heat exchanger 70. At the same time, the refrigerant 2 and the cooling water 6 exchange heat 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 is not used to raise the temperature of the lubricating oil 5, and is Heat can be exchanged with the cooling water 6. As a result, more of the heat of the exhaust gas 4 can be used for the heat input of the refrigerant 2 to assist the function of the vaporizer 13, so that the heating performance of the air conditioner 1 can be improved.

In the exhaust heat recovery device 3 according to the embodiment of the present invention, in addition to the heat exchange between the exhaust gas 4 and the cooling water 6, the exhaust gas 4 and the lubricating oil 5 are exchanged in the second heat exchanger 60. By configuring this to be possible, a decrease in the temperature of the lubricating oil 5 in the internal combustion engine 20 can be suppressed. Therefore, the 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, thereby suppressing a decrease in fuel efficiency of the internal combustion engine 20.

Furthermore, in the exhaust heat recovery device 3 according to the embodiment of the present invention, during the heating operation of the air conditioner 1, the exhaust gas 4 and the lubricating oil 5 are not heat exchanged in the second heat exchanger 60. By exchanging heat between the exhaust gas 4 and the cooling water 6 in the third heat exchanger 70, heat can be exchanged between the cooling water 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 exchanged with the cooling water 6 in the first heat exchanger 15, and more of the heat of the exhaust gas 4 is vaporized. Since the heat input of the refrigerant 2 for assisting the function of the air conditioner 13 can be used, the heating performance of the air conditioner 1 can be improved.

In the exhaust heat recovery device 3 according to the embodiment of the present invention, by setting a predetermined temperature and directly monitoring the temperature of the lubricating oil 5, when the temperature of the lubricating oil 5 is below the predetermined temperature, the controller 80 By sending a signal to the switching section 35 on the exhaust gas flow path 30, efficient switching operation in the switching section 35 can be performed.

In the exhaust heat recovery device 3 according to the embodiment of the present invention, by providing the second switching part 35b, the backflow of the exhaust gas 4 to the main flow path 33 is prevented, thereby reliably blocking the main flow path 33. be able to. Thereby, during the heating operation of the air conditioner 1, heat exchange between the exhaust gas 4 and the lubricating oil 5 can be reliably suppressed, and the exhaust gas 4 can be heat exchanged with the cooling water 6, which is involved in improving heating performance.

In the air conditioner 1 according to the embodiment of the present invention, the first heat exchanger 15 is provided between the expansion valve 12 and the vaporizer 13 in the refrigerant cycle, so that the first heat exchanger 15 is provided between the expansion valve 12 and the vaporizer 13 in the refrigerant cycle. In the exchanger 15, the cooling water 6 and the refrigerant 2 exchange heat, and the temperature of the refrigerant 2 increases. Thereby, the heat of the exhaust gas 4 in the exhaust heat recovery device 3 can be exchanged with the cooling water 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 for the heat input of the refrigerant 2 to assist the function of the vaporizer 13, so that heating performance can be improved.

Hereinafter, an exhaust heat recovery device and an air conditioner equipped with the same according to a modification of an embodiment of the present invention will be described. The exhaust heat recovery device according to this modification and the air conditioner equipped with the same are different in the control method of 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. The description of the configurations that are the same as those of the exhaust heat recovery device 3 and the air conditioner 1 including the same according to the first embodiment of the present invention will not be repeated.

A control unit included in an exhaust heat recovery device according to a modification of an embodiment of the present invention can control the second heat exchanger using a signal from an internal combustion engine or the like. Specifically, the control unit estimates the temperature of the lubricating oil from the rotation speed, load, operating time, or cooling water temperature of the internal combustion engine, or the outside temperature. Thereby, the control unit confirms that the lubricating oil temperature is lower than the predetermined temperature.

In the exhaust heat recovery device and the air conditioner equipped with the same according to a modification of the embodiment of the present invention, the control unit estimates the temperature of the lubricating oil based on a signal from an internal combustion engine, etc. By configuring the exhaust gas and the lubricating oil to be able to exchange heat, it is possible to suppress a decrease in the temperature of the lubricating oil in the internal combustion engine. Therefore, the increase in the viscosity of the lubricating oil is suppressed, and the sliding characteristics of the sliding member in the internal combustion engine are maintained, thereby suppressing a decrease in fuel efficiency of the internal combustion engine.

Furthermore, in the exhaust heat recovery device and the air conditioner equipped with the same according to a modification of the embodiment of the present invention, the exhaust gas is Instead of using heat to raise the temperature of the lubricating oil, it can be used to exchange heat with the cooling water in the first heat exchanger and use it to input heat to the refrigerant that assists the function of the vaporizer. Heating performance can be improved.

Note that the above-described embodiments disclosed herein are illustrative in all respects, and are not the basis for a limited interpretation. Therefore, the technical scope of the present disclosure should not be interpreted only by the embodiments described above. In addition, all changes within the meaning and scope of the claims are included. In the above description of the embodiments, combinable configurations may be combined with each other.

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 vaporizer, 14 refrigerant flow path, 14a first refrigerant Channel, 14b Second refrigerant channel, 14c Third refrigerant channel, 14d Fourth refrigerant channel, 15 First heat exchanger, 20 Internal combustion engine, 21 Radiator, 22 Heat exchange medium, 30 Exhaust gas channel, 31 exhaust port, 32 gas piping, 33 main flow path, 34 bypass flow path, 35 switching section, 35a first switching section, 35b second switching section, 40 lubricating oil flow path, 41 lubricating oil piping, 50 cooling water flow path, 51 th 1 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 unit.

Claims (4)

An exhaust heat recovery device installed in an internal combustion engine that drives a compressor of an air conditioner,
an exhaust gas flow path through which exhaust gas from the internal combustion engine flows;
a lubricating oil flow path that circulates lubricating oil to the internal combustion engine;
a cooling water flow path having a first heat exchanger capable of circulating cooling water for cooling the internal combustion engine and exchanging heat between the cooling water and a refrigerant flowing through a refrigerant cycle of the air conditioner;
a second heat exchanger connected to the exhaust gas flow path and the lubricating oil flow path and capable of exchanging heat between the exhaust gas and the lubricating oil;
a third heat exchanger that 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;
It is equipped with a control section,
The exhaust gas flow path is
a main flow path to which the second heat exchanger is connected;
a bypass flow path that branches from the main flow path upstream of the second heat exchanger and bypasses the second heat exchanger;
The control unit controls a first state in which 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 cut off, and a first state in which exhaust gas is guided to the bypass flow path and a switching unit configured to switch between a second state of blocking the flow to a portion of the main flow path where the second heat exchanger is provided;
During heating operation of the air conditioner, the switching unit is switched to the second state by the control unit, and the exhaust gas and the cooling water are exchanged with heat in the third heat exchanger, and the first heat An exhaust heat recovery device in which heat is exchanged between refrigerant and cooling water in an exchanger. The exhaust heat recovery device according to claim 1, wherein the control unit controls the switching unit to switch to the first state when the temperature of lubricating oil is lower than a predetermined temperature. The main flow path is connected to the bypass flow path downstream of the second heat exchanger,
The switching section includes a first switching section provided on the upstream side and a second switching section provided on the downstream side,
The exhaust heat recovery device according to claim 1 or 2, wherein in the first state, the bypass flow path is blocked by the first switching section and the second switching section. The exhaust heat recovery device according to claim 1;
a condenser that condenses the refrigerant compressed by the compressor;
an expansion valve that expands the refrigerant that has passed through the condenser;
a vaporizer that vaporizes the refrigerant that has passed through the expansion valve and returns the vaporized refrigerant to the compressor;
The refrigerant cycle is configured by a refrigerant circulating through the compressor, the condenser, the expansion valve, and the vaporizer,
The first heat exchanger is an air conditioner provided between the expansion valve and the vaporizer in the refrigerant cycle.

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