JP2014134175A - Rankine cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rankine cycle device which uses a volume adjustment mechanism and is able to detect leakage of a working fluid.SOLUTION: A working fluid circuit 11 of a rankine cycle device 10 for a vehicle comprises a volume adjustment mechanism 60 which may supply a refrigerant to a radiator 30. The volume adjustment mechanism 60 includes a storage chamber 63 which is disposed between the downstream side of the radiator 30 and the upstream side of a boiler 50 when viewed in a circulation direction of the working fluid circuit 11 and stores the refrigerant. Further, the volume adjustment mechanism 60 includes: a piston 62 which moves in the storage chamber 63 and varies the volume of the storage chamber 63; and a control part 75 which controls the piston 62 and determines if refrigerant leakage from the working fluid circuit 11 occurs on the basis of a difference between a reference travel distance and an actual travel distance of the piston 62.

Description

  The present invention relates to a Rankine cycle device having a working fluid circuit in which a working fluid circulates by connecting a pump, a boiler, an expander, and a radiator.

  In this type of Rankine cycle device, in order to prevent the occurrence of cavitation in the pump, it is important to make the working fluid sucked into the pump into a stable liquid state. As means for making the working fluid sucked into the pump into a liquid state, it has been proposed to provide a receiver and a subcooler downstream of the condenser and upstream of the pump in the circulating direction of the working fluid in the Rankine cycle.

  By the way, in the Rankine cycle device, when the working fluid leaks from the Rankine cycle and the amount of the working fluid decreases, the amount of mechanical energy recovered by the expander may decrease or the Rankine cycle itself may not be established. Therefore, in the Rankine cycle device, leakage of the working fluid is detected. For example, in the Rankine cycle device of Patent Document 1, a receiver provided between the pump and the condenser is provided with a level sensor (liquid level detection means), and leakage of the working fluid is detected from the liquid level detected by the level sensor. Is detected.

German Patent Application Publication No. 10201111654

  By the way, it is conceivable to provide a volume adjustment tank (volume adjustment mechanism) that can adjust the volume of the Rankine cycle, instead of the receiver, as means for converting the working fluid sucked into the pump into a liquid state. In the circulation direction of the working fluid in the Rankine cycle, a volume adjustment tank is provided downstream of the condenser and upstream of the pump, and liquid working fluid is sent from the volume adjustment tank to the condenser. Then, since the entire volume of the Rankine cycle including the volume adjustment tank is reduced, the working fluid is relatively increased. As a result, the degree of supercooling of the working fluid increases in the condenser, and the working fluid can be made into a stable liquid state.

  However, in such a volume adjustment tank, while the working fluid circulates through the Rankine cycle, the volume adjustment tank is filled with the working fluid, and the leakage of the working fluid cannot be detected by the liquid level sensor. there were.

  An object of the present invention is to provide a Rankine cycle apparatus capable of detecting leakage of a working fluid even in a Rankine cycle apparatus using a volume adjusting mechanism.

  In order to solve the above problem, the Rankine cycle device according to claim 1 includes a pump that pumps the working fluid, a boiler that heats the working fluid pumped by the pump by exhaust heat from the exhaust heat source, and An expander that expands the working fluid heated by the boiler to recover mechanical energy, a radiator that dissipates heat from the working fluid expanded by the expander, the pump, the boiler, the expander, and the heat dissipation A Rankine cycle device having a working fluid circuit through which the working fluid circulates, wherein the working fluid circuit includes a volume adjustment mechanism capable of supplying the working fluid to the radiator. The adjustment mechanism is disposed between the downstream of the radiator including the radiator and the upstream of the boiler including the boiler in the circulation direction of the working fluid circuit, and accommodates the working fluid The accommodation chamber, a movable portion that moves in the accommodation chamber to change the volume of the accommodation chamber, and controls the movable portion, and based on the difference between the reference movement amount and the actual movement amount of the movable portion, And a control unit for determining leakage of the working fluid from the working fluid circuit.

  According to this, the working fluid in the storage chamber is supplied to the radiator by the movable portion of the volume adjustment mechanism. At this time, since the volume of the storage chamber is reduced, the volume of the entire working fluid circuit including the storage chamber of the volume adjusting mechanism is reduced as compared with before the volume of the storage chamber is reduced. On the other hand, since the working fluid circulating in the working fluid circuit is constant, the amount of working fluid relative to the volume of the working fluid circuit increases relatively. The working fluid supplied from the volume adjusting mechanism increases the amount of working fluid in the radiator. As a result, the amount of heat released in the gas-liquid mixed phase region of the radiator is reduced, while the amount of heat released in the liquid phase is increased. As a result, the working fluid should be subcooled to prevent cavitation. Can do.

  In the Rankine cycle device provided with such a volume adjustment mechanism, a physical quantity (for example, pressure) that matches the operating condition can be obtained under operating conditions set so that required mechanical energy can be recovered by the expander. Thus, the volume in the working fluid circuit is set. In the volume adjustment mechanism, the movable portion is moved by the reference movement amount so that a physical quantity under the set operating condition can be obtained. However, if the working fluid leaks, the movable part moves to a position different from the predetermined position in order to obtain a physical quantity under the operating condition, and the reference movement amount and the actual movement amount of the movable part. Will cause a difference. Therefore, the control unit can detect leakage of the working fluid from the working fluid circuit by grasping this difference.

The volume adjustment mechanism may include a motor that moves the movable part, the motor being signal-connected to the control unit, and the actual movement amount may be calculated from a rotation amount of the motor.
According to this, in the volume adjustment mechanism, the movable part is moved by the reference movement amount by the motor so that the physical quantity under the operating condition can be obtained. That is, the motor rotates at a predetermined rotation amount so that a physical quantity under the operating condition can be obtained. However, if there is leakage of the working fluid, the actual rotation amount of the motor for obtaining the physical quantity under the operating condition is larger than the predetermined rotation amount, and there is no leakage of the working fluid. In comparison, the motor rotates so that the volume of the storage chamber of the volume adjusting mechanism is reduced. As a result, the actual movement amount of the movable part becomes larger than the reference movement amount. Therefore, the control unit can detect leakage of the working fluid from the working fluid circuit by comparing the reference movement amount calculated from the rotation amount of the motor with the actual movement amount. Therefore, since the rotation amount of the motor can be obtained every time the movable part is moved by the motor, the leakage of the working fluid can be confirmed each time the movable part is moved.

  The movable portion is provided with a magnetic body, and the volume adjusting mechanism has a housing that partitions the storage chamber together with the movable portion, and the housing is movable according to the magnetic force of the magnetic body. A position detection unit for detecting the position of the unit may be provided, and the actual movement amount may be calculated based on the position detected by the position detection unit.

  According to this, in the volume adjustment mechanism, when the movable part moves by the reference movement amount so as to obtain the physical quantity under the operating condition, the position detection part detects the magnetic force of the magnetic body, and this magnetic force is determined in advance. Value. However, if the working fluid leaks, the magnetic force detected by the position detection unit is determined in advance at the position where the movable part has moved (the position where the actual movement amount has moved) in order to obtain the physical quantity under the operating conditions. It is different from the value that was done. The control unit can calculate the actual movement amount from the detected magnetic force, and can detect the leakage of the working fluid from the working fluid circuit from the difference between the actual movement amount and the reference movement amount. Accordingly, since the magnetic force of the magnetic body can be detected every time the movable part is moved, it is possible to confirm the leakage of the working fluid every time the movable part moves.

  According to the present invention, it is possible to detect leakage of working fluid even in a Rankine cycle device using a volume adjusting mechanism.

The schematic diagram which shows the Rankine-cycle apparatus of embodiment. The table | surface which shows the relationship between motor rotation amount and the presence or absence of refrigerant | coolant leakage. (A) is sectional drawing which shows the volume adjustment mechanism without refrigerant | coolant leakage, (b) is sectional drawing which shows the volume adjustment mechanism with refrigerant | coolant leakage. The figure which shows the leak detection of another example.

Hereinafter, an embodiment in which the Rankine cycle device is embodied as a vehicle Rankine cycle device will be described with reference to FIGS.
As shown in FIG. 1, the vehicle Rankine cycle device 10 includes a working fluid circuit 11 that is a closed circuit formed by sequentially connecting an expander 20, a radiator 30, a pump 40, and a boiler 50. In the working fluid circuit 11, a refrigerant as a working fluid circulates. In the working fluid circuit 11, the refrigerant flows along the arrangement order of the expander 20, the radiator 30, the pump 40, and the boiler 50 and circulates in the working fluid circuit 11.

  The outlet of the pump 40 and the heat absorption part 50 a of the boiler 50 are connected via the first passage 21. Further, the boiler 50 has a heat radiating portion 50b, and the heat radiating portion 50b is provided on an exhaust passage E1 connected to an engine E as an exhaust heat source. The exhaust having the exhaust heat of the engine E is exhausted from the muffler E2 after being radiated by the heat radiating portion 50b. The engine E has a drive shaft Ea, and the drive shaft 20a of the expander 20 is directly operatively connected to the drive shaft Ea of the engine E via a belt 20b. The mechanical energy generated by the expander 20 is transmitted to the drive shaft Ea of the engine E.

  The heat absorption part 50 a of the boiler 50 and the inlet of the expander 20 are connected via the second passage 22. The outlet of the expander 20 and the inlet of the radiator 30 are connected via a third passage 23. The outlet of the radiator 30 and the inlet of the pump 40 are connected via the fourth passage 24. In the boiler 50, a liquid refrigerant and a gaseous refrigerant are mixed, and a liquid phase region including only the liquid refrigerant, a gas phase region including only the gaseous refrigerant, and a gas-liquid mixed phase region exist. . Also in the radiator 30, a liquid refrigerant and a gaseous refrigerant are mixed, and a gas phase region, a liquid phase region, and a mixed phase region exist. The liquid phase region of the radiator 30 and the liquid phase region of the boiler 50 are connected via the pump 40, the first passage 21, and the fourth passage 24.

  In the boiler 50, the low-temperature and high-pressure liquid refrigerant pumped by the pump 40 is heated by exchanging heat with the exhaust flowing through the exhaust passage E1 of the engine E. The expander 20 expands the refrigerant that is heated and vaporized in the boiler 50 to generate mechanical energy. The radiator 30 cools (dissipates heat) and condenses the refrigerant expanded in the expander 20 by exchanging heat with the outside air. The pump 40 pumps liquid refrigerant into the working fluid circuit 11. A pump motor 31 is operatively connected to the drive shaft 40 a of the pump 40. In the working fluid circuit 11, one end of a branch path 25 is connected to the fourth path 24 downstream of the radiator 30 and upstream of the pump 40 in the refrigerant circulation direction. A volume adjusting mechanism 60 is connected to the other end.

  As shown in FIGS. 1 and 3A, the volume adjusting mechanism 60 includes a housing 62 in which a piston 62 as a movable portion is accommodated, and the piston 62 forms a refrigerant accommodating chamber 63 in the housing 61. It is partitioned. The accommodation chamber 63 communicates with the branch path 25. Therefore, the storage chamber 63 is disposed between the downstream side of the radiator 30 and the upstream side of the boiler 50 in the circulation direction of the working fluid circuit 11. A rod 64 is connected to the piston 62, and a motor 66 is connected to a protruding end portion of the rod 64 from the housing 61 via a power transmission mechanism 65. A control unit 75 is signal-connected to the motor 66. When the motor 66 is driven under the control of the control unit 75, the piston 62 moves in the housing 61 via the power transmission mechanism 65.

  The branch path 25 is provided with a pressure sensor 51, and the fourth passage 24 is provided with a temperature sensor 52. The pressure sensor 51 and the temperature sensor 52 are signal-connected to the control unit 75.

  The storage unit 75a of the control unit 75 stores a plurality of types of operating conditions of the working fluid circuit 11 in the vehicle Rankine cycle device 10. The operating conditions include, for example, when the vehicle is in an idle state and when traveling at 60 km / h. Under each operating condition, the pressure and temperature of the refrigerant in the working fluid circuit 11 are set in advance so that the amount of mechanical energy recovered from the expander 20 becomes a predetermined amount, and the volume adjusting mechanism 60 The volume adjustment amount is determined in advance. The volume adjustment amount by the volume adjustment mechanism 60 is set according to the rotation amount of the motor 66, and the rotation amount of the motor 66 is determined in advance according to each operation condition. The movement amount of the piston 62 is preset according to the rotation amount of the motor 66, and the movement amount of the piston 62 according to the rotation amount of the motor 66 is set as a reference movement amount. The reference movement amount increases as the rotation amount of the motor 66 increases, and the piston 62 decreases the volume of the storage chamber 63 and decreases the volume of the working fluid circuit 11.

  An alarm 76 is wired to the control unit 75. The alarm 76 is arranged in the visible range of the passenger of the vehicle, such as in the passenger compartment. When the control unit 75 detects a refrigerant leak in the working fluid circuit 11 of the vehicle Rankine cycle device 10, the control unit 75 informs the occupant of the refrigerant leak by the notification device 76. The control unit 75 determines refrigerant leakage from the working fluid circuit 11 based on the difference between the preset reference movement amount and the actual movement amount of the piston 62. The actual movement amount of the piston 62 is calculated from the actual rotation amount of the motor 66.

  In the vehicle Rankine cycle device 10, when the volume adjustment mechanism 60 is driven and the piston 62 moves in the direction of decreasing the volume of the storage chamber 63, the refrigerant in the storage chamber 63 is supplied to the radiator 30. At this time, since the volume of the storage chamber 63 is reduced, the volume of the entire working fluid circuit 11 including the storage chamber 63 is reduced as compared with that before the volume adjustment mechanism 60 is driven. On the other hand, since the refrigerant circulating in the working fluid circuit 11 is constant, the amount of refrigerant relative to the volume of the working fluid circuit 11 increases relatively. Then, when the refrigerant is supplied from the volume adjustment mechanism 60 to the radiator 30, the amount of refrigerant in the radiator 30 increases. As a result, the heat dissipation amount in the gas-liquid mixed phase region of the radiator 30 is reduced, while the heat dissipation amount in the liquid phase region is increased, and as a result, the degree of supercooling is reduced so that cavitation in the pump 40 does not occur in the refrigerant. Can be given.

Next, the effect | action of the Rankine-cycle apparatus 10 for vehicles is demonstrated based on FIG.2 and FIG.3.
When operating the vehicle Rankine cycle device 10 under a certain operating condition, the control unit 75 determines that the refrigerant in the working fluid circuit 11 has a predetermined pressure and a temperature based on the detected pressure and the detected temperature by the pressure sensor 51 and the temperature sensor 52. The volume adjusting mechanism 60 is driven to adjust the volume of the working fluid circuit 11 so that the temperature is reached.

  Specifically, the control unit 75 controls the rotation amount of the motor 66 (referred to as a command motor rotation amount N) according to the reference movement amount so that the volume adjustment mechanism 60 has a predetermined volume adjustment amount. . As shown in FIG. 3A, when there is no refrigerant leakage from the working fluid circuit 11, the motor 66 rotates by the command motor rotation amount N, and the piston 62 moves to a preset position. At this time, the actual movement amount of the piston 62 is calculated from the command motor rotation amount N, and the calculated actual movement amount is equivalent to a preset reference movement amount. When the volume of the working fluid circuit 11 decreases, the pressure detected by the pressure sensor 51 and the temperature detected by the temperature sensor 52 are adjusted to a predetermined pressure and temperature.

  On the other hand, if there is refrigerant leakage from the working fluid circuit 11, the pressure detected by the pressure sensor 51 and the temperature sensor even if the motor 66 rotates by the command motor rotation amount N and the volume of the working fluid circuit 11 is adjusted. The temperature detected at 52 is different from the predetermined pressure and temperature. For this reason, as shown in FIG. 3B, the control unit 75 rotates the motor 66 at an actual motor rotation amount M larger than the command motor rotation amount N so that a predetermined pressure and temperature are obtained. Let As a result, the motor 66 rotates so as to reduce the volume of the storage chamber 63. At this time, the actual movement amount of the piston 62 is calculated from the actual motor rotation amount M, and the calculated actual movement amount is larger than a preset reference movement amount, and there is a difference between the actual movement amount and the reference movement amount. Arise. Therefore, the piston 62 is arranged at a position moved in the direction of reducing the volume of the storage chamber 63 from a preset position.

  Then, the control unit 75 has a larger value (M> N) of the actual movement amount (actual motor rotation amount M) than the predetermined reference movement amount (command motor rotation amount N). 11, it is determined that refrigerant leakage has occurred. That is, the controller 75 detects refrigerant leakage from the working fluid circuit 11. When the refrigerant leak is detected, the control unit 75 informs the occupant that the refrigerant leak has occurred by the alarm 76.

According to the above embodiment, the following effects can be obtained.
(1) In the vehicle Rankine cycle device 10 including the volume adjustment mechanism 60, the control unit 75 determines the difference between the reference movement amount of the piston 62 and the actual movement amount (difference in the rotation amount of the motor 66) in the volume adjustment mechanism 60. Based on this, the presence or absence of refrigerant leakage from the working fluid circuit 11 was confirmed. For this reason, even if it is the volume adjustment mechanism 60 which cannot employ | adopt a liquid level sensor, a refrigerant | coolant leak can be detected.

  (2) The piston 62 of the volume adjusting mechanism 60 is moved by the motor 66. The actual movement amount and the reference movement amount of the piston 62 are calculated from the rotation amount of the motor 66. For this reason, if refrigerant leakage occurs in the working fluid circuit 11, the motor 66 is rotated so that the volume of the storage chamber 63 is reduced in order to obtain the operating condition of the working fluid circuit 11, and the actual motor rotation amount M Is larger than the predetermined command motor rotation amount N, and the actual movement amount is also larger than the reference movement amount. Therefore, the control unit 75 can detect leakage of the working fluid from the working fluid circuit 11 based on the predetermined command motor rotation amount N and the actual motor rotation amount M. Therefore, since the rotation amount of the motor 66 can be obtained each time the piston 62 is moved by the motor 66, the refrigerant leakage can be confirmed each time the piston 62 moves.

  (3) When refrigerant leakage from the working fluid circuit 11 has occurred, the alarm 76 notifies the passenger of the refrigerant leakage. For this reason, the passenger can restore the vehicle Rankine cycle device 10 based on the notification from the alarm 76 before the output of the vehicle Rankine cycle device 10 is reduced or the Rankine cycle itself is not established.

In addition, you may change the said embodiment as follows.
As shown in FIG. 4, the position of the piston 62 may be detected by a position detector 67 provided in the housing 61. The position detection unit 67 is a magnetic sensor, and a permanent magnet 62 a (magnetic material) is attached to the outer peripheral surface of the piston 62. The position detector 67 is signal-connected to the controller 75, detects the magnetic force of the permanent magnet 62 a, and outputs a signal related to the magnetic force to the controller 75. In the storage unit 75a of the control unit 75, the magnetic force of the permanent magnet 62a detected by the position detection unit 67 is determined in advance according to each operation condition. That is, the magnetic force of the permanent magnet 62a detected according to the reference movement amount of the piston 62 is determined in advance.

  The control unit 75 controls the rotation amount of the motor 66 so that the volume adjustment mechanism 60 has a predetermined volume adjustment amount. At this time, if there is no refrigerant leakage from the working fluid circuit 11, the motor 66 rotates by the rotation amount commanded in advance, and the piston 62 moves by the reference movement amount and moves to a predetermined position. Then, the position detection unit 67 detects a predetermined magnetic force. Then, the control unit 75 calculates the reference movement amount of the piston 62 based on the detected magnetic force.

  On the other hand, if refrigerant leaks from the working fluid circuit 11, the motor 66 rotates by the commanded rotation amount, and the pressure and temperature sensor detected by the pressure sensor 51 even if the volume of the working fluid circuit 11 is adjusted. The temperature detected at 52 is different from the predetermined pressure and temperature. For this reason, the control unit 75 rotates the motor 66 by a rotation amount larger than the commanded rotation amount so as to obtain a predetermined pressure and temperature, thereby reducing the volume of the storage chamber 63. For this reason, the piston 62 is arranged at a position moved in a direction of reducing the volume of the storage chamber 63 from a predetermined position. That is, the actual movement amount of the piston 62 is larger than the reference movement amount. Then, the permanent magnet 62a integrated with the piston 62 is also separated from the predetermined position, and the magnetic force detected by the position detector 67 is smaller than the predetermined magnetic force. Then, the control unit 75 calculates the actual movement amount of the piston 62 based on the detected magnetic force, and determines that refrigerant leakage has occurred in the working fluid circuit 11 based on the difference between the actual movement amount and the reference movement amount. To do.

The magnetic material may be other than the permanent magnet as long as it has magnetism.
In the embodiment, the control unit 75 detects the refrigerant leakage when the actual motor rotation amount M becomes larger than the predetermined command motor rotation amount N (M> N). Not limited to this. When the value of the actual motor rotation amount M becomes larger than the predetermined command motor rotation amount N by a predetermined amount, the control unit 75 may detect refrigerant leakage.

  In the embodiment, the piston 62 is moved by the motor 66, but the piston 62 may be moved by a spring. In this case, the control unit 75 calculates the actual movement amount of the piston 62 based on the change in spring length (spring force), and the refrigerant leaks from the working fluid circuit 11 based on the difference between the actual movement amount and the reference movement amount. May be determined.

The movable part may be a diaphragm instead of the piston 62.
○ The volume adjustment mechanism may be a pump whose volume can be changed.
○ The volume adjustment mechanism may be provided anywhere as long as it is a liquid phase region.

The volume adjusting mechanism 60 may be connected anywhere as long as it is always in the liquid phase region when the working fluid circuit 11 is operated.
○ The type of the engine E is not limited, and may be, for example, a gasoline engine or a diesel engine.

○ The exhaust heat may be changed as appropriate, such as engine cooling water or EGR gas.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) The movable part is driven by a spring, and the control part is configured to output the working fluid from the working fluid circuit based on a difference between an actual movement amount and a reference movement amount of the movable part determined by the spring. Rankine cycle device for judging leakage of water.

  (B) A Rankine cycle device in which the movable part is a piston.

  E ... Engine as exhaust heat source, 10 ... Rankine cycle device for vehicle as Rankine cycle device, 11 ... Working fluid circuit, 20 ... Expander, 30 ... Radiator, 40 ... Pump, 50 ... Boiler, 60 ... Volume adjustment mechanism , 61 ... housing, 62 ... piston as a movable part, 62a ... permanent magnet as a magnetic body, 63 ... accommodation chamber, 66 ... motor, 67 ... position detection part, 75 ... control part.

Claims (3)

A pump for pumping the working fluid;
A boiler that heats the working fluid pumped by the pump by exhaust heat from an exhaust heat source;
An expander for recovering mechanical energy by expanding the working fluid heated by the boiler;
A radiator that dissipates heat from the working fluid expanded by the expander;
A Rankine cycle device including the pump, the boiler, the expander, and a working fluid circuit to which the working fluid circulates by being connected to the radiator,
The working fluid circuit includes a volume adjustment mechanism capable of supplying working fluid to the radiator.
The volume adjusting mechanism is disposed between the downstream of the radiator including the radiator and the upstream of the boiler including the boiler in the circulation direction of the working fluid circuit, and a storage chamber that stores the working fluid. ,
A movable part that moves in the storage chamber and varies the volume of the storage chamber;
A Rankine comprising: a control unit that controls the movable part and that determines leakage of the working fluid from the working fluid circuit based on a difference between a reference movement amount and an actual movement amount of the movable part. Cycle equipment.   2. The Rankine according to claim 1, wherein the volume adjustment mechanism includes a motor that moves the movable part, the motor is connected to the control unit in a signal, and the actual movement amount is calculated by a rotation amount of the motor. Cycle equipment.   The movable part is provided with a magnetic body, and the volume adjusting mechanism has a housing that divides the storage chamber together with the movable part, and the housing includes a housing of the movable part according to the magnetic force of the magnetic body. The Rankine cycle apparatus according to claim 1, wherein a position detection unit that detects a position is provided, and the actual movement amount is calculated from a position detected by the position detection unit.