JP2018040337A - Waste heat collection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an excessive rise of pressure in a waste heat collection device.SOLUTION: A waste heat collection device comprises a decompression safety device 51 for reducing pressure by injecting a low-temperature liquid-phase fluid into a high-pressure circuit. The decompression safety device 51 comprises a pressure receiving movable part 60 in which two pressure receiving parts 60a, 60b which are different in pressure receiving areas are oppositely arranged. The second pressure receiving part 60b which is narrow in the pressure receiving area constitutes a wall face of a second cylinder 64 which is filled with the liquid-phase fluid. The pressure receiving movable part 60 is pressed against the side of the first pressure receiving part 60a from the side of the second pressure receiving part 60b by a coil spring 66. Pressure in the high-pressure circuit acts on both the pressure receiving parts 60a, 60b. When the pressure in the high-pressure circuit reaches a threshold or higher, a force received by the pressure receiving movable part 60 resulting from a difference of the pressure receiving areas exceeds an elastic force of the coil spring 66. The pressure receiving movable part 60 moves to the side of the second pressure receiving part 60b from the side of the first pressure receiving part 60a, and thereby the low-temperature liquid-phase fluid in the second cylinder 64 is injected into the high-pressure circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waste heat recovery apparatus, and more particularly to a waste heat recovery apparatus that recovers waste heat of an internal combustion engine using a Rankine cycle system.

  A waste heat recovery device that recovers waste heat of an internal combustion engine using a Rankine cycle system has been proposed. In the waste heat recovery device, the liquid phase fluid is evaporated or boiled by the waste heat of the internal combustion engine to change it into a gas phase fluid, and the work is taken out by expanding the gas phase fluid with a turbine, and the expanded gas phase fluid is condensed. It is made to return to a liquid phase fluid. Japanese Patent Laying-Open No. 2015-230139 describes that in such a waste heat recovery apparatus, a circuit for bypassing the turbine is provided and a bypass valve is arranged there.

JP 2015-230139 A JP 2008-051479 A JP-A-4-0453393 JP 2008-014625 A

  In the waste heat recovery device, the liquid phase fluid may boil violently due to a sudden increase in waste heat of the internal combustion engine, and the internal pressure may increase excessively due to the generated steam. In addition, the internal pressure may increase excessively due to a failure in the pump that sends out the liquid phase fluid or a failure such as clogging of the turbine nozzle. In such a case, an increase in pressure can be suppressed by opening the bypass valve. However, if the bypass valve is opened after the pressure increase is detected, a sudden pressure increase cannot be handled. In addition, there is no way to suppress the pressure rise when the bypass valve fails and is stuck closed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a waste heat recovery apparatus that can suppress an excessive increase in internal pressure due to generated steam. .

In order to achieve the above object, a waste heat recovery apparatus according to the present invention includes an evaporator that evaporates a liquid phase fluid by waste heat of an internal combustion engine to change it into a gas phase fluid, and a gas phase that is sent from the evaporator. A superheater that superheats the fluid by heat exchange with the exhaust of the internal combustion engine, a turbine that expands the gaseous fluid that has passed through the superheater to extract work, and condenses the gaseous fluid that has passed through the turbine to condense liquid A condenser for returning to the phase fluid, a pump for supplying the liquid phase fluid obtained by the condenser to the evaporator, and a bypass for bypassing the turbine and connecting the downstream of the evaporator and the upstream of the condenser In a waste heat recovery apparatus comprising a circuit and a bypass valve provided in the bypass circuit,
When the pressure in the high pressure circuit, which is a fluid circuit from the pump to the turbine or the bypass valve, exceeds a set pressure, the pressure in the high pressure circuit is injected by injecting a low-temperature liquid phase fluid into the high pressure circuit. Equipped with a decompression safety device to decompress
The decompression safety device is:
A pressure-receiving movable unit comprising: a first pressure-receiving unit; and a second pressure-receiving unit having a smaller pressure-receiving area than the first pressure-receiving unit provided to face the first pressure-receiving unit;
A part of the wall surface is constituted by the second pressure receiving part, and the volume is changed by the movement of the pressure receiving movable part, and a cylinder filled with a liquid phase fluid therein,
A spring that applies an elastic force from the second pressure receiving portion side to the first pressure receiving portion side with respect to the pressure receiving movable portion;
A pressure introducing circuit that connects the high-pressure circuit and the first pressure-receiving unit, and causes the pressure in the high-pressure circuit to act on the first pressure-receiving unit;
A liquid phase fluid injection circuit that connects the cylinder and the high pressure circuit, and allows a liquid phase fluid to flow from the cylinder to the high pressure circuit,
In the spring, when the pressure in the high-pressure circuit becomes equal to or higher than the set pressure, the pressure-receiving movable portion resists the elastic force of the spring from the first pressure-receiving portion side to the second pressure-receiving portion side. It is adjusted so that it may move to.

  According to the waste heat recovery apparatus according to the present invention, when the pressure in the high-pressure circuit becomes equal to or higher than the set pressure, the decompression safety device operates. In the decompression safety device, the pressure receiving movable part moves from the first pressure receiving part side to the second pressure receiving part side against the elastic force of the spring, and the liquid phase fluid filled in the cylinder is injected into the high pressure circuit. The By injecting the low-temperature liquid phase fluid, boiling of the liquid phase fluid in the evaporator is suppressed, and an increase in pressure in the high-pressure circuit is suppressed.

It is a figure which shows the structure of the waste heat recovery apparatus of Embodiment 1. FIG. FIG. 6 is a diagram for explaining the operation of the decompression safety device according to the first embodiment. FIG. 6 is a diagram for explaining the operation of the decompression safety device according to the first embodiment. It is a figure for demonstrating the operation | movement as a safety valve of the pressure reduction safety apparatus of Embodiment 1. FIG. It is a figure which shows the structure of the modification of the decompression safety device of Embodiment 1. FIG. It is a figure which shows the structure of the modification of the decompression safety device of Embodiment 1. FIG. It is a figure which shows the structure of the waste heat recovery apparatus of Embodiment 2. FIG. It is a side view which shows the example of mounting to a vehicle the waste heat recovery apparatus of Embodiment 2. It is a front view which shows the example of mounting to a vehicle the waste heat recovery apparatus of Embodiment 2. FIG. It is a figure which shows the structure of the decompression safety device of Embodiment 3. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. However, in the embodiment shown below, when referring to the number of each element, quantity, quantity, range, etc., unless otherwise specified or clearly specified in principle, the reference However, the present invention is not limited to these numbers. Further, the structures described in the embodiments described below are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

Embodiment 1 FIG.
1-1. Configuration of Waste Heat Recovery Apparatus FIG. 1 is a diagram illustrating a configuration of the waste heat recovery apparatus 1 according to the first embodiment. The waste heat recovery apparatus 1 includes a fluid circulation circuit in which a plurality of fluid pipes 31, 32, 33, 34, 35, 36, and 37 are connected in an annular shape. In the fluid circulation circuit, a pump 24 for sending the liquid phase fluid from the fluid pipe 37 to the fluid pipe 31 is disposed. The waste heat recovery apparatus 1 moves waste heat of the exhaust gas to the fluid by exchanging heat between the exhaust gas flowing through the exhaust passage 4 of the internal combustion engine 2 and the fluid circulating in the circulation circuit. The fluid may be any fluid that is liquid at normal temperature and changes into a gas-phase fluid by boiling or evaporating with the heat of the internal combustion engine 2. In this embodiment, this fluid is water.

  A preheater 10, an evaporator 12, and a superheater 14, which are heat exchangers, are attached to the exhaust passage 4 in order from the downstream side in the exhaust gas flow direction. The outlet of the pump 24 is connected to the preheater 10 by a fluid pipe 31. The preheater 10 is connected to the evaporator 12 by a fluid pipe 32. The evaporator 12 is connected to the superheater 14 by a fluid pipe 33. The water sent from the pump 24 absorbs heat from the exhaust gas in the preheater 10 and becomes hot hot water. The hot water absorbs heat from the higher temperature exhaust gas in the evaporator 12 to boil or evaporate into water vapor. The steam absorbs heat from the higher-temperature exhaust gas in the superheater 14 and becomes superheated steam.

  The superheater 14 is connected to the turbine 18 by a fluid pipe 33. The turbine 18 takes out work by expanding the water vapor sent from the superheater 14. A turbine nozzle 16 is provided at a connection portion between the fluid pipe 33 and the turbine 18. The water vapor is sprayed from the turbine nozzle 16 to the turbine 18 to rotate the turbine 18. The rotation of the turbine 18 is transmitted to the output shaft of the internal combustion engine 2 via a reduction gear (not shown). That is, the work taken out by the turbine 18 is used for assisting the internal combustion engine 2. However, it is also possible to drive the generator by the turbine 18 and store the generated electricity in the storage battery.

  The turbine 18 is connected to the condenser 20 by a fluid pipe 35. The steam expanded by the turbine 18 is cooled and condensed by the condenser 20 and returned to liquid phase water. A catch tank 22 for storing water is disposed below the condenser 20 in the vertical direction. The condenser 20 is connected to the catch tank 22 by a fluid pipe 36. Water generated by condensation of water vapor in the condenser 20 is temporarily stored in the catch tank 22. The catch tank 22 is connected to the inlet of the pump 24 by a fluid pipe 37. The water in the catch tank 22 is sent again to the preheater 10 by the pump 24. The pump 24 is a positive displacement pump such as a vane pump.

  The waste heat recovery apparatus 1 includes a bypass circuit that bypasses the turbine 18 and a bypass valve 42 provided in the bypass circuit. The bypass circuit includes a fluid pipe 40 branched from the fluid pipe 33 and connected to the bypass valve 42, and a fluid pipe 41 connecting the bypass valve 42 and the fluid pipe 35. The bypass valve 42 is a control valve that operates according to a signal from a control device (not shown).

  In the waste heat recovery apparatus 1 configured as described above, two fluid circuits having different pressures during operation are formed. The fluid circuit from the pump 24 to the turbine nozzle 16 or the bypass valve 42 constitutes a high-pressure circuit where high pressure is applied during operation. Specifically, the high pressure circuit includes fluid pipes 31, 32, 33, 34, 40, a preheater 10, an evaporator 12, and a superheater 14. The fluid circuit from the turbine 18 or bypass valve 42 to the pump 24 constitutes a low pressure circuit where low pressure is applied during operation. Specifically, the low pressure circuit includes fluid pipes 41, 35, 36, 37, a condenser 20, and a catch tank 22.

1-2. Configuration of Decompression Safety Device The waste heat recovery device 1 is a depressurization safety device 51 that depressurizes the pressure in the high-pressure circuit by injecting low-temperature water into the high-pressure circuit when the pressure in the high-pressure circuit exceeds a set pressure. Is provided. The decompression safety device 51 includes a pressure receiving movable unit 60 in which a first piston 60A and a second piston 60B are integrated with the same shaft. The diameter of the first piston 60A is smaller than the diameter of the second piston 60B.

  The decompression safety device 51 includes a first cylinder 62 whose part of the wall surface is constituted by the first pressure receiving portion 60a which is the piston surface of the first piston 60A, and whose volume is changed by the axial movement of the pressure receiving movable portion 60. In addition, the decompression safety device 51 includes a second cylinder 64 having a part of the wall surface constituted by the second pressure receiving portion 60b which is the piston surface of the second piston 60B, and the volume of which is changed by the axial movement of the pressure receiving movable portion 60. Prepare. The first cylinder 62 and the second cylinder 64 are integrated with the same shaft, and the pressure receiving movable portion 60 is accommodated therein. That is, the decompression safety device 51 is a force increasing mechanism formed by combining two cylinder mechanisms having different pressure receiving areas.

  Inside the first cylinder 62, a coil spring 66 is accommodated on the opposite side of the first piston 60A from the first pressure receiving portion 60a. The second piston 60 </ b> B protrudes into the second cylinder 64 through the center of the coil spring 66. The coil spring 66 is a compression spring, and applies an elastic force to the pressure receiving movable portion 60 from the second pressure receiving portion 60b side to the first pressure receiving portion 60a side.

  The second cylinder 64 is filled with liquid phase water. The water filled in the second cylinder 64 is water stored in the catch tank 22 and is low-temperature water before being heated in the high-pressure circuit.

  One end of a fluid pipe 73 is connected to the ceiling portion of the first cylinder 62 (when the upper side in the figure is the upper side in the vertical direction). The other end of the fluid pipe 73 is connected to the fluid pipe 40 constituting the high-pressure circuit. The fluid pipe 73 is a pressure introduction circuit that causes the pressure in the high pressure circuit to act on the first pressure receiving portion 60a of the first piston 60A.

  One end of a fluid pipe 71 is connected to the bottom of the second cylinder 64. The other end of the fluid pipe 71 is connected to the evaporator 12 constituting the high-pressure circuit. The second cylinder 64 is filled with liquid phase water. The fluid pipe 71 is a liquid phase fluid injection circuit that allows water to flow from the second cylinder 64 to the high pressure circuit. The fluid pipe 71 is provided with a check valve 75 that allows the flow of fluid from the second cylinder 64 to the high-pressure circuit and prevents the flow in the opposite direction.

  The fluid pipe 71 is connected to one end of a fluid pipe 72 for supplying liquid phase water in the low pressure circuit to the second cylinder 64. The fluid pipe 72 is connected to the catch tank 22 constituting the low pressure circuit. The fluid pipe 72 is provided with a check valve 76 that allows the flow of fluid from the low pressure circuit to the second cylinder 64 and prevents the flow in the opposite direction.

1-3. Operation of Depressurized Safety Device In the depressurized safety device 51 configured as described above, the position of the pressure receiving movable unit 60 is such that the pressure acting on the first pressure receiving unit 60a, the pressure acting on the second pressure receiving unit 60b, and the coil spring It is determined by the relationship with the elastic force 66 Here, the position of the pressure receiving movable portion 60 when the first piston 60 </ b> A comes closest to the ceiling surface of the first cylinder 62 is set as the initial position of the pressure receiving movable portion 60. The amount of contraction of the coil spring 66 when the pressure receiving movable unit 60 is in the initial position is set as the initial contraction amount. The area of the first pressure receiving part 60a is A1, the pressure acting on the first pressure receiving part 60a is P1, the area of the second pressure receiving part 60b is A2, the pressure acting on the second pressure receiving part 60b is P2, and the spring constant of the coil spring 66 Is represented by K, and the initial contraction amount of the coil spring 66 is represented by X0, the operating force F acting on the pressure receiving movable unit 60 at the initial position is represented by the following formula 1. When the operating force F expressed by Equation 1 becomes a positive value, the pressure receiving movable unit 60 moves from the initial position toward the second cylinder 64 to reduce the volume of the second cylinder 64.
F = ((P1 * A1) − (P2 * A2)) − K * X0 Equation 1

  FIG. 2 is a diagram illustrating the operation of the decompression safety device 51 when the pressure in the high-pressure circuit rises. The pressure in the high pressure circuit acts on the first pressure receiving part 60a via the fluid pipe 73 which is a pressure introducing circuit. When the pressure in the high pressure circuit rises, the pressure acting on the first pressure receiving portion 60a also rises, and the operating force F acting on the pressure receiving movable portion 60 rises. When the operating force F becomes a positive value, a force that pushes the second piston 60B into the second cylinder 64 acts, and the pressure in the second cylinder 64 increases. During this time, the check valve 76 is closed, and the check valve 75 is opened when the pressure in the second cylinder 64 becomes the same as the pressure in the high pressure circuit. The pressure in the high-pressure circuit at this time is a set pressure at which the decompression safety device 51 operates. The set pressure is determined based on the pressure resistance of the fluid pipe or the device. When the decompression safety device 51 is operated, the same pressure equal to or higher than the set pressure is applied to both the first pressure receiving part 60a and the second pressure receiving part 60b. The spring constant K of the coil spring 66 is adjusted so that the operating force F becomes a positive value when P1 and P2 are equal to or higher than the set pressure in the above formula.

The operating force F acting on the pressure receiving movable unit 60 during the operation of the decompression safety device 51 is expressed by the following formula 2. Here, P is the pressure in the high-pressure circuit that acts on both the first pressure receiving part 60a and the second pressure receiving part 60b. Fs is a spring force (elastic force) of the coil spring 66, and when the movement amount from the initial position of the pressure receiving movable portion 60 is represented by X, it is represented by the following Expression 3. The pressure-receiving movable unit 60 moves to a position where the operating force F represented by Equation 2 becomes zero, and an amount of water corresponding to the amount of movement is injected from the second cylinder 64 to the high-pressure circuit via the fluid pipe 71. The
F = P * (A1-A2) -Fs Formula 2
Fs = K * (X0 + X) Equation 3

  The low-temperature water stored in the second cylinder 64 is poured into the evaporator 12 of the high-pressure circuit, so that boiling of the water in the evaporator 12 is suppressed and the pressure in the high-pressure circuit decreases. FIG. 3 is a diagram illustrating the operation of the decompression safety device 51 when the pressure in the high-pressure circuit decreases. When the pressure in the high pressure circuit decreases, the pressure acting on the first pressure receiving portion 60 a decreases, and the pressure receiving movable portion 60 is pushed back by the coil spring 66. The pressure receiving movable part 60 moves in the direction of the first cylinder 62 and the volume of the second cylinder 64 is increased, so that the pressure in the second cylinder 64 decreases. Thereby, the check valve 75 is closed and the check valve 76 is opened. When the check valve 75 is closed, water injection from the second cylinder 64 to the evaporator 12 is stopped, and when the check valve 76 is opened, water in the catch tank 22 is passed through the fluid pipe 72 to the second cylinder 64. Supplied to. When the second cylinder 64 is filled with water, the decompression safety device 51 becomes operable again.

  The pressure in the high-pressure circuit rises due to various factors such as intensification of boiling in the evaporator 12 due to a sudden rise in the exhaust temperature of the internal combustion engine 2, a closed failure of the bypass valve 42, and clogging of the turbine nozzle 16 due to adhesion of foreign matter. The cause is included. Regardless of the cause, it is possible to suppress an excessive increase in the pressure in the high-pressure circuit by operating the decompression safety device 51 as described above. Further, when the pressure in the high-pressure circuit decreases due to the operation of the decompression safety device 51, the decompression safety device 51 automatically returns to the original state. Therefore, even if the pressure in the high-pressure circuit repeatedly increases, the decompression safety device 51 can be operated each time to decrease the pressure.

1-4. Operation as a safety valve of the decompression safety device When the pressure increase in the high pressure circuit is excessively large, it may not be sufficient to inject the water in the second cylinder 64 into the evaporator 12. In such a case, the decompression safety device 51 operates as a safety valve that releases the pressure in the high-pressure circuit to the atmosphere.

  FIG. 4 is a view for explaining the operation of the decompression safety device 51 as a safety valve. Two atmosphere release pipes 68 and 69 are connected to the first cylinder 62 for opening the space on the opposite side of the first pressure receiving portion 60a out of the two spaces partitioned by the first piston 60A. ing. As shown in FIGS. 2 and 3, normally, the atmosphere release pipes 68 and 69 are not in communication with the space on the first pressure receiving portion 60 a side of the first cylinder 62. However, when the first piston 60A is pushed into the back of the first cylinder 62 due to an increase in the pressure acting on the first pressure receiving portion 60a, as shown in FIG. 4, the atmosphere is released to the atmosphere connected to the side surface of the first cylinder 62. The pipe 69 communicates with the space on the first pressure receiving portion 60 a side of the first cylinder 62. As a result, the pressure in the high-pressure circuit is released to the atmosphere via the atmosphere opening pipe 69.

  The limit pressure at which the decompression safety device 51 is operated as a safety valve is determined by the amount of displacement X1 from the initial position of the first cylinder 62 shown in FIG. 4, that is, the amount of contraction of the coil spring 66. The limit pressure is determined based on the strength of the fluid pipe and the device, and the connection position of the atmosphere release pipe 69 is determined so that the atmosphere release pipe 69 communicates with the high pressure circuit with a displacement amount X1 corresponding to the limit pressure.

  When the pressure in the high pressure circuit increases, the decompression safety device 51 first suppresses boiling by injecting the water in the second cylinder 64 into the evaporator 12 and attempts to decrease the pressure in the high pressure circuit. . The decompression safety device 51 operates as a safety valve only when the pressure in the high pressure circuit continues to rise despite the water in the second cylinder 64 being injected into the evaporator 12, and the pressure in the high pressure circuit is reduced to the atmospheric pressure. Open in. According to this, it is possible to minimize the influence on the outside world while avoiding damage to the fluid pipe and equipment due to excessive pressure.

5. Hereinafter, a modified example of the decompression safety device 51 will be described with reference to the drawings. FIG. 5 is a diagram showing a configuration of a decompression safety device 52 as a first modification. In the decompression safety device 52, a container 63 filled with an incompressible fluid is attached to the ceiling surface of the first cylinder 62. A fluid pipe 73 as a pressure introduction circuit is connected to the container 63. Here, the incompressible fluid is liquid phase water, and the space on the first pressure receiving portion 60a side of the first cylinder 62 is also filled with water. The container 63 stores a water amount equal to or larger than the amount of change in the volume of the second cylinder 64 due to the movement of the second piston 60B. According to the configuration of the reduced pressure safety device 52, it is possible to more easily apply pressure to the first pressure receiving portion 60a of the first piston 60A.

  FIG. 6 is a diagram showing a configuration of a decompression safety device 53 as a second modified example. The decompression safety device 53 has a fluid pipe 73 as a pressure introduction circuit connected to the evaporator 12 in the configuration of the first modification. The connection position of the fluid pipe 73 to the evaporator 12 is a position lower than the water surface H in the evaporator 12. Therefore, in the configuration of the second modified example, the space from the fluid pipe 73 to the container 63 is filled with water. A fluid pipe 74 that connects the evaporator 12 and the container 63 is provided in parallel with the fluid pipe 73. The fluid pipe 73 is provided with a check valve 77 that allows only water flow from the evaporator 12 to the container 63 and prevents backflow. On the other hand, the fluid pipe 74 is provided with a check valve 78 that allows only water flow from the container 63 to the evaporator 12 and prevents backflow.

  According to the configuration of the decompression safety device 53, when the pressure in the high pressure circuit rises, water flows from the evaporator 12 to the container 63 through the fluid pipe 73, and the high pressure circuit is supplied to the first pressure receiving part 60a of the first cylinder 62. The pressure inside acts. Then, when the low-temperature water in the second cylinder 64 is injected into the evaporator 12 to reduce the pressure in the high-pressure circuit, the water flows from the container 63 to the evaporator 12 through the fluid pipe 74, and the first The water supplied to the cylinder 62 is returned to the evaporator 12. Since the water in the first cylinder 62 is lower in temperature than the boiling water in the evaporator 12, the water is returned from the first cylinder 62 to the evaporator 12, so that the water in the evaporator 12 boils. Is further suppressed.

Embodiment 2. FIG.
2-1. Configuration of Waste Heat Recovery Device FIG. 7 is a diagram illustrating a configuration of the waste heat recovery device 101 according to the second embodiment. The waste heat recovery apparatus 101 according to the second embodiment is configured to recover not only the waste heat that the exhaust gas of the internal combustion engine 2 has but also the waste heat that the cooling water of the internal combustion engine 2 has. A refrigerant channel 6 through which a refrigerant flows is formed in the cylinder block and the cylinder head of the internal combustion engine 2. The refrigerant flow path 6 includes a water jacket surrounding the cylinder. The refrigerant boils in the refrigerant flow path 6 due to the heat generated by the internal combustion engine 2, and the internal combustion engine 2 is cooled by the heat of vaporization when the liquid-phase refrigerant changes to the gas-phase refrigerant. At this time, the refrigerant flow path 6 functions as an evaporator for boiling or evaporating the liquid-phase refrigerant flowing in the interior by the heat of the internal combustion engine 2. In the present embodiment, water is used as the refrigerant.

  The refrigerant flow path 6 of the internal combustion engine 2 is connected to a gas-liquid separator 116 via a fluid pipe 135. A liquid phase refrigerant is discharged from the refrigerant flow path 6 together with the gas phase refrigerant. The gas-liquid separator 116 separates the refrigerant that has flowed into the gas-liquid separator 116 into a liquid-phase refrigerant and a gas-phase refrigerant. The gas-liquid separator 116 is connected to the refrigerant circulation pump 128 via the fluid pipe 133. The liquid phase refrigerant separated by the gas-liquid separator 116 flows into the refrigerant circulation pump 128 via the fluid pipe 133 and is sent to the refrigerant flow path 6 by the refrigerant circulation pump 128.

  A preheater 110, an evaporator 112, and a superheater 114, which are heat exchangers, are attached to the exhaust passage 4 in order from the downstream side in the exhaust gas flow direction. The preheater 110 is connected to the outlet of the pump 126 by a fluid pipe 131. The pump 126 is a positive displacement pump such as a vane pump and pumps the liquid-phase refrigerant to the preheater 110. A fluid pipe 132 is connected to the preheater 110, and the other end of the fluid pipe 132 is connected to the fluid pipe 133. In the fluid pipe 133, a fluid pipe 134 is connected to a position closer to the gas-liquid separator 116 than a position where the fluid pipe 132 is connected. The other end of the fluid pipe 134 is connected to the evaporator 112. The evaporator 112 is connected to the gas-liquid separator 116 by a fluid pipe 136. The gas-liquid separator 116 is connected to the superheater 114 by a fluid pipe 137.

  The liquid-phase refrigerant sent out from the pump 126 absorbs heat from the exhaust gas in the preheater 110. The liquid phase refrigerant heated by the preheater 110 is supplied to the evaporator 112 together with the liquid phase refrigerant separated by the gas-liquid separator 116. The liquid refrigerant absorbs heat from the higher-temperature exhaust gas in the evaporator 112 and boils or evaporates to become a gas-phase refrigerant. The gas-phase refrigerant generated in the evaporator 112 is supplied to the superheater 114 via the gas-liquid separator 116 together with the gas-phase refrigerant discharged from the refrigerant flow path 6 of the internal combustion engine 2. The gas-phase refrigerant absorbs heat from the higher-temperature exhaust gas in the superheater 114 and becomes superheated steam.

  The superheater 114 is connected to the turbine 120 by a fluid pipe 138. In the turbine 120, work is taken out by expanding the gas-phase refrigerant sent from the superheater 114. A turbine nozzle 118 is provided at a connection portion between the fluid pipe 138 and the turbine 120. The gas phase refrigerant is sprayed from the turbine nozzle 118 to the turbine 120 to rotate the turbine 120. The rotation of the turbine 120 is transmitted to the output shaft of the internal combustion engine 2 via a reduction gear (not shown), or used for driving the generator.

  The turbine 120 is connected to the condenser 122 by a fluid pipe 139. The gas-phase refrigerant expanded in the turbine 120 is cooled and condensed by the condenser 122 and returned to the liquid-phase refrigerant. A catch tank 124 for storing a liquid-phase refrigerant is disposed below the condenser 122 in the vertical direction. The condenser 122 is connected to the catch tank 124 by a fluid pipe 140. The catch tank 124 is connected to the inlet of the pump 126 by a fluid pipe 141. The water in the catch tank 124 is sent again to the preheater 110 by the pump 126.

  The waste heat recovery apparatus 101 includes a bypass circuit that bypasses the turbine 120 and a bypass valve 152 provided in the bypass circuit. The bypass circuit includes a fluid pipe 150 branched from the fluid pipe 137 and connected to the bypass valve 152, and a fluid pipe 151 connecting the bypass valve 152 and the fluid pipe 139. The bypass valve 152 is a control valve that operates according to a signal from a control device (not shown).

  The waste heat recovery apparatus 101 includes a decompression safety device 51. The configuration of the decompression safety device 51 is as described in the first embodiment. The second cylinder 64 of the decompression safety device 51 is filled with a liquid phase refrigerant used for cooling the internal combustion engine 2. A fluid pipe 73 as a pressure introduction circuit is connected to a fluid pipe 150 constituting a high-pressure circuit. A fluid pipe 71 as a liquid phase fluid injection circuit is connected to a fluid pipe 132 constituting a high pressure circuit. The fluid pipe 72 for replenishing the second cylinder 64 with the liquid phase refrigerant is connected to a catch tank 124 that constitutes a low-pressure circuit. The decompression safety device 51 is configured to decompress the pressure in the high-pressure circuit by injecting a low-temperature liquid-phase refrigerant into the high-pressure circuit when the pressure in the high-pressure circuit becomes equal to or higher than the set pressure.

  The waste heat recovery apparatus 101 according to the second embodiment may include a reduced pressure safety device 52 (see FIG. 5) or a reduced pressure safety device 53 (see FIG. 6), which is a modified example, instead of the reduced pressure safety device 51. it can.

2-2. Example of mounting waste heat recovery apparatus on vehicle FIG. 8 is a side view showing an example of mounting the waste heat recovery apparatus 101 of the second embodiment on a vehicle. FIG. 9 is a front view showing an example of mounting the waste heat recovery apparatus 101 of the second embodiment on a vehicle. In this mounting example, the internal combustion engine 2 and the transmission 200 are placed horizontally under the hood 204 at the front of the vehicle. The superheater 114 constituting the waste heat recovery apparatus 101 is integrated with the exhaust manifold of the internal combustion engine 2. The superheater 114 is disposed on the front side in the vehicle traveling direction with respect to the internal combustion engine 2. A gas-liquid separator 116 is disposed in the vicinity of the superheater 114. As shown in FIG. 9, the gas-liquid separator 116 is arranged above the transmission 200 so as to be aligned with the internal combustion engine 2 when viewed from the front of the vehicle.

  A condenser 122 is disposed at the foremost position under the hood 204, that is, at a position where the traveling wind is most easily received. A decompression safety device 51 is disposed at a position between the condenser 122 and the internal combustion engine 2. The decompression safety device 51 is arranged upright so that the first cylinder 62 is positioned above the vertical direction and the second cylinder 64 is positioned below the vertical direction. Further, the mounting position of the decompression safety device 51 is adjusted so that the second cylinder 64 protrudes downward from the bottom of the condenser 122 when viewed from the front of the vehicle. By disposing the decompression safety device 51 at such a position, the second cylinder 64 can be cooled by running wind. By cooling the second cylinder 64 and lowering the temperature of the liquid-phase refrigerant filled therein, the effect of lowering the pressure of the high-pressure circuit by injecting the liquid-phase refrigerant can be enhanced.

Embodiment 3 FIG.
FIG. 10 is a diagram illustrating a configuration of the decompression safety device 54 according to the third embodiment. The decompression safety device 54 according to the third embodiment is configured as a force-increasing mechanism that is a combination of a diaphragm mechanism and a cylinder mechanism. Specifically, the decompression safety device 54 includes a pressure-receiving movable portion that includes a diaphragm 80 and a piston 81. The decompression safety device 54 includes a diaphragm chamber 82 that houses the diaphragm 80 and a cylinder 84 that is integrated with the diaphragm chamber 82 with the same shaft. The cylinder 84 is filled with a liquid phase fluid. The piston 81 moves in the cylinder 84 in the axial direction. In this configuration, the surface of the diaphragm 80 where the piston 81 is not attached is the first pressure receiving portion 80a, and the surface of the piston 81 in the cylinder 84 is the second pressure receiving portion 81a.

  Of the two spaces of the diaphragm chamber 82 partitioned by the diaphragm 80, a coil spring 86 is accommodated in the space where the piston 81 is disposed. The piston 81 protrudes into the cylinder 84 through the center of the coil spring 86. The coil spring 86 is a compression spring, and applies an elastic force from the second pressure receiving portion 81a side to the first pressure receiving portion 80a side to the pressure receiving movable portion composed of the diaphragm 80 and the piston 81. The spring constant of the coil spring 86 is such that when the pressure in the high pressure circuit becomes equal to or higher than the set pressure, the pressure receiving movable portion resists the elastic force of the coil spring 86 from the first pressure receiving portion 80a side to the second pressure receiving portion 81a. It has been adjusted to move to the side.

  Of the two spaces of the diaphragm chamber 82 partitioned by the diaphragm 80, a fluid pipe 73 is connected to the space on the first pressure receiving portion 80a side which is the pressure receiving surface of the diaphragm 80. The fluid pipe 73 is a pressure introduction circuit that causes the pressure in the high pressure circuit to act on the first pressure receiving portion 80a. The other space of the diaphragm chamber 82 is connected to an air release pipe 88 for opening the space to the atmosphere.

  A fluid pipe 71 is connected to the cylinder 84 as a liquid phase fluid injection circuit that allows the liquid phase fluid to flow from the cylinder 84 to the high pressure circuit. The fluid pipe 71 is provided with a check valve 75 that allows the flow of fluid from the cylinder 84 to the high-pressure circuit and prevents the flow in the opposite direction. The fluid pipe 71 is connected to a fluid pipe 72 for replenishing the cylinder 84 with the liquid phase fluid in the low pressure circuit. The fluid pipe 72 is provided with a check valve 76 that permits the flow of fluid from the low pressure circuit to the cylinder 84 and prevents the flow in the opposite direction.

  The decompression safety device 54 configured as described above can be used as an alternative to the decompression safety device 51 in the waste heat recovery device 1 of the first embodiment or the waste heat recovery device 101 of the second embodiment.

Other embodiments.
The connection destination of the fluid pipe 73 as the pressure introducing circuit is not limited to the above embodiment as long as the pressure of the high pressure circuit can be taken out. For example, the fluid pipe 73 may be connected to the superheaters 14 and 114. The connection destination of the fluid pipe 71 as the liquid phase fluid injection circuit is not limited to the above embodiment as long as the liquid phase fluid can be injected into the high pressure circuit. For example, the fluid pipe 71 may be connected to a site downstream of the evaporators 12 and 112. The connection destination of the fluid pipe 72 for replenishing the liquid phase fluid is not limited to the above embodiment as long as the liquid phase fluid is present in the low pressure circuit. For example, the fluid pipe 72 may be connected near the inlets of the pumps 24 and 126.

1,101 Waste heat recovery device 2 Internal combustion engine 4 Exhaust passage 6 Refrigerant flow path (evaporator)
10, 110 Preheater 12, 112 Evaporator 14, 114 Superheater 16, 118 Turbine nozzle 18, 120 Turbine 20, 122 Condenser 22, 124 Catch tank 24, 126 Pump 42, 152 Bypass valve 51, 52, 53, 54 Pressure reducing safety device 60 Pressure receiving movable part 60A First piston 60a First pressure receiving part 60B Second piston 60b Second pressure receiving part 62 First cylinder 64 Second cylinder 66 Coil spring 71 Fluid pipe (liquid phase fluid injection circuit)
72 Fluid pipe (pressure introduction circuit)
80 Diaphragm 80a First pressure receiving portion 81 Piston 81a Second pressure receiving portion 82 Diaphragm chamber 84 Cylinder 86 Coil spring 116 Gas-liquid separator 128 Refrigerant circulation pump

Claims (1)

An evaporator that evaporates a liquid phase fluid by a waste heat of the internal combustion engine to change it into a gas phase fluid, and a superheater that superheats the gas phase fluid delivered from the evaporator by heat exchange with the exhaust gas of the internal combustion engine, A turbine that expands the gas phase fluid that has passed through the superheater to extract work, a condenser that condenses the gas phase fluid that has passed through the turbine and returns it to a liquid phase fluid, and a liquid phase fluid obtained by the condenser Waste heat comprising: a pump that supplies the evaporator to the evaporator; a bypass circuit that bypasses the turbine and connects the downstream of the evaporator and the upstream of the condenser; and a bypass valve provided in the bypass circuit In the recovery device,
When the pressure in the high pressure circuit, which is a fluid circuit from the pump to the turbine or the bypass valve, exceeds a set pressure, the pressure in the high pressure circuit is injected by injecting a low-temperature liquid phase fluid into the high pressure circuit. Equipped with a decompression safety device to decompress
The decompression safety device is:
A pressure-receiving movable unit comprising: a first pressure-receiving unit; and a second pressure-receiving unit having a smaller pressure-receiving area than the first pressure-receiving unit provided to face the first pressure-receiving unit;
A part of the wall surface is constituted by the second pressure receiving part, and the volume is changed by the movement of the pressure receiving movable part, and a cylinder filled with a liquid phase fluid therein,
A spring that applies an elastic force from the second pressure receiving portion side to the first pressure receiving portion side with respect to the pressure receiving movable portion;
A pressure introducing circuit that connects the high-pressure circuit and the first pressure-receiving unit, and causes the pressure in the high-pressure circuit to act on the first pressure-receiving unit;
A liquid phase fluid injection circuit that connects the cylinder and the high pressure circuit, and allows a liquid phase fluid to flow from the cylinder to the high pressure circuit,
In the spring, when the pressure in the high-pressure circuit becomes equal to or higher than the set pressure, the pressure-receiving movable portion resists the elastic force of the spring from the first pressure-receiving portion side to the second pressure-receiving portion side. A waste heat recovery device that is adjusted to move to

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