WO2012169375A1

WO2012169375A1 - Waste heat recovery apparatus

Info

Publication number: WO2012169375A1
Application number: PCT/JP2012/063468
Authority: WO
Inventors: 英文森; 井口　雅夫; 榎島　史修
Original assignee: 株式会社豊田自動織機
Priority date: 2011-06-06
Filing date: 2012-05-25
Publication date: 2012-12-13
Also published as: JP2012251517A

Abstract

This waste heat recovery device recovers waste heat generated by a combustion engine that outputs a rotational driving force. A first heat exchanger transfers heat from a cooling fluid that cools the combustion engine to a refrigerant. A second heat exchanger transfers heat from exhaust gas discharged from the combustion engine to the refrigerant. An expander is linked to the combustion engine in such a manner that a driving force is transmitted from the combustion engine. A bypass refrigerant flow channel branches off from a refrigerant flow channel and bypasses the first heat exchanger. A refrigerant flow rate regulator regulates the flow rate of the refrigerant in the bypass refrigerant flow channel. A temperature detector detects the temperature of the refrigerant in the refrigerant flow channel upstream from the expander. A control unit controls the flow rate regulation state of the refrigerant flow rate regulator on the basis of information detected by the temperature detector.

Description

Waste heat recovery device

The present invention includes a first heat exchanger that transmits heat of a cooling fluid that cools a combustion engine that outputs a rotational driving force to a refrigerant, and a second heat exchanger that transfers heat of exhaust gas of the combustion engine to the refrigerant. The present invention relates to a waste heat recovery apparatus including an expander directly connected to a combustion engine.

FIG. 10 of Patent Document 1 discloses a fluid machine used in this kind of waste heat recovery apparatus. In the fluid machine disclosed in FIG. 10, a pulley, an expander, and an alternator that are coupled to the engine via a belt so that driving force is transmitted from the engine are coupled to a rotating shaft. Thereby, even when the thermal energy of the Rankine cycle cannot be obtained sufficiently, the rotational driving force of the engine is input to the alternator via the pulley and the rotating shaft to generate electric power.

JP 2004-340139 A

The high-temperature and high-pressure refrigerant heated by the waste heat is introduced into the expander and expands in the expander. The expander obtains rotational energy by the expansion of the refrigerant and drives the alternator. Such an expander has a seal member to prevent the refrigerant from leaking from the refrigerant confinement space in the expander. From the viewpoint of the heat resistance of the seal member (expansion machine reliability), it is necessary to control the temperature of the refrigerant below the heat resistance temperature of the seal member.

∙ The amount of waste heat from the engine may fluctuate even when the engine speed is the same. That is, even when the engine speed is the same, the temperature of the cooling water may fluctuate. When the engine speed is not so high and the temperature of the cooling water is high, the refrigerant flowing into the expander becomes high temperature.

However, since the expander is connected to the engine via a pulley, the rotation speed of the expander is restricted by the rotation speed of the engine. Therefore, when the engine speed is not so high and the temperature of the cooling water is high, the amount of refrigerant flowing into the expander is small (that is, the refrigerant flow rate is small), and the temperature of the refrigerant introduced into the expander is low. It becomes too high. Therefore, it is necessary to throw away the heat of the refrigerant upstream from the expander from the viewpoint of the reliability of the expander, and waste is generated in using the waste heat of the engine.

An object of the present invention is to improve the efficiency of waste heat utilization in a waste heat recovery apparatus having an expander connected to a combustion engine so that the driving force is transmitted from the combustion engine that outputs a rotational driving force. .

In order to achieve the above object, a waste heat recovery apparatus according to an aspect of the present invention includes a first heat exchanger, a second heat exchanger, an expander, a refrigerant channel, a bypass refrigerant channel, and a refrigerant. A flow rate adjustment unit, a temperature detection unit, and a control unit are provided. The waste heat recovery device recovers waste heat generated in a combustion engine that outputs a rotational driving force. The first heat exchanger transmits heat of a cooling fluid that cools the combustion engine to the refrigerant. The second heat exchanger transmits heat of exhaust gas discharged from the combustion engine to the refrigerant. The expander is coupled to the combustion engine so that driving force is transmitted from the combustion engine. The refrigerant passes through the refrigerant flow path. The bypass refrigerant flow path branches off from the refrigerant flow path and bypasses the first heat exchanger. The refrigerant flow rate adjusting unit adjusts the refrigerant flow rate in the bypass refrigerant flow path. The temperature detection unit detects a refrigerant temperature in the refrigerant flow channel upstream of the expander. The control unit controls a flow rate adjustment state of the refrigerant flow rate adjustment unit based on detection information of the temperature detection unit.

The schematic diagram which shows the waste-heat recovery apparatus which concerns on 1st Embodiment. FIG. 2 is an overall side cross-sectional view of the waste heat recovery device of FIG. 1. The top view which shows the 2nd heat exchanger and bypass pipe of FIG. Sectional drawing which shows the 2nd heat exchanger of FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 3. Sectional drawing which shows the temperature action | operation actuator which controls the on-off valve of FIG. 1, and the refrigerant | coolant header tank of FIG. The schematic diagram which shows the waste heat recovery apparatus which concerns on 2nd Embodiment.

Hereinafter, a first embodiment embodying the present invention will be described with reference to FIGS.

As shown in FIG. 1, the waste heat recovery device 11 includes an engine 12 (combustion engine) that is a waste heat source, and a Rankine cycle circuit 13.

In the Rankine cycle circuit 13, the refrigerant heated by the waste heat from the engine 12 circulates. The waste heat recovery equipment 14 constituting the waste heat recovery apparatus 11 constitutes a part of the Rankine cycle circuit 13.

As shown in FIG. 2, the entire housing 35 constituting the waste heat recovery apparatus 14 includes a center housing 36, a front housing 37 connected to the front end (left end in FIG. 2) of the center housing 36, and the rear of the center housing 36. And a rear housing 38 connected to the end (the right end in FIG. 2).

A rotating shaft 40 is rotatably supported by

bearings

51 and 52 on a partition wall 361 integrally formed at the front end of the center housing 36 and a front end wall 371 of the front housing 37, and the rotating shaft 40 in the front housing 37 is supported. A rotor 41 is fixed to the rotor. A stator 42 is fixed to the inner peripheral surface of the front housing 37 so as to surround the rotor 41. The rotating shaft 40, the stator 42 provided with the coil 421, and the rotor 41 constitute an alternator 43 (generator). The rotating shaft 40 is a rotor shaft of the alternator 43.

The alternator 43 has a function of generating electric power in the coil 421 of the stator 42 as the rotor 41 rotates.

A battery 45 is electrically connected to the alternator 43. The electric power generated by the alternator 43 is stored in the battery 45.

The rotary shaft 40 passes through the front end wall 371 of the front housing 37 and protrudes out of the front housing 37, and a pulley 56 is fixed to the protruding end portion of the rotary shaft 40. A belt 57 is wound around the pulley 56.

As shown in FIG. 1, the belt 57 is wound around a pulley 69 fixed to a crankshaft 68 that is a rotation output shaft of the engine 12.

As shown in FIG. 2, a side plate 62 is fixed in the center housing 36 so as to face the partition 361. A pump chamber 64 is formed between the partition wall 361 and the side plate 62. The rotating shaft 40 passes through the partition 361 and the side plate 62. In the pump chamber 64, a drive gear 65 fixed to the rotary shaft 40 and a driven gear 66 that meshes with the drive gear 65 are disposed. The pump chamber 64, the drive gear 65 and the driven gear 66 constitute a gear pump 67.

A support block 63 is fixed in the center housing 36. A rotating shaft 40 is rotatably supported by the support block 63 via a bearing 71. A scroll type expander 72 is provided between the support block 63 and the rear housing 38.

Next, the configuration of the expander 72 will be described.

An eccentric shaft 73 is provided at the rear end of the rotary shaft 40. The eccentric shaft 73 revolves around the rotation axis of the rotation shaft 40 by the rotation of the rotation shaft 40. A movable scroll 74 is rotatably supported on the eccentric shaft 73 via a bush 75 and a bearing 76. The movable scroll 74 includes a movable side end plate 741 supported by a bearing 76 and a spiral movable side spiral wall 742 protruding from the movable side end plate 741.

A fixed scroll 77 is fixed in the rear part of the center housing 36 so as to face the movable scroll 74. The fixed scroll 77 includes a fixed side end plate 771 and a spiral fixed side spiral wall 772 protruding from the fixed side end plate 771 toward the support block 63. The movable spiral wall 742 of the movable scroll 74 and the fixed spiral wall 772 of the fixed scroll 77 are engaged with each other to form an expansion chamber 78 whose volume can be changed.

A supply chamber 79 is formed between the fixed side end plate 771 and the rear housing 38, and a supply port 773 is formed at the center of the fixed side end plate 771 so as to communicate with the supply chamber 79. An introduction port 381 is formed in the rear housing 38. A discharge chamber 80 is formed between the side plate 62 and the support block 63. The refrigerant in the expansion chamber 78 is discharged to the discharge chamber 80. A discharge port 362 is formed on the peripheral wall of the center housing 36 so as to communicate with the discharge chamber 80.

Next, the Rankine cycle circuit 13 in the waste heat recovery apparatus 11 will be described.

As shown in FIG. 1, the Rankine cycle circuit 13 includes an expander 72, a condenser 29, a gear pump 67, a first heat exchanger 20, and a second heat exchanger 21 that constitute the waste heat recovery device 14.

The first heat exchanger 20 includes a heat radiating part 201 and a heat absorbing part 202. The heat radiating unit 201 is provided on the cooling water circulation path 23 connected to the engine 12. A radiator 24 is provided on the cooling water circulation path 23. Cooling water (cooling fluid) that has cooled the engine 12 of the vehicle circulates through the cooling water circulation path 23 and radiates heat by the heat radiating unit 201 and the radiator 24.

The second heat exchanger 21 is provided on the refrigerant flow path between the first heat exchanger 20 and the expander 72 and is provided on the exhaust flow path 15 connected to the engine 12. The heat of the exhaust gas exhausted from the engine 12 to the exhaust passage 15 is transmitted to the refrigerant in the refrigerant passage via the second heat exchanger 21. Exhaust gas in the exhaust passage 15 is exhausted from the muffler 26.

The introduction port 381 (see FIG. 2) in the expander 72 is connected to the second heat exchanger 21 via the supply flow path 28. The refrigerant heated by the first heat exchanger 20 and the second heat exchanger 21 is introduced into the expander 72 via the supply flow path 28. The condenser 29 is connected to the discharge port 362 (see FIG. 2) on the expander 72 side via the discharge flow path 30. The low-pressure refrigerant expanded by the expander 72 is discharged to the condenser 29 via the discharge flow path 30. A gear pump 67 is connected to the downstream side of the condenser 29 via the second flow path 31. The first heat exchanger 20 is connected to the downstream side of the gear pump 67 via the first flow path 22.

The second flow path 31, the first flow path 22, the connection flow path 25 between the first heat exchanger 20 and the second heat exchanger 21, the supply flow path 28, and the discharge flow path 30 are the Rankine cycle circuit 13. A refrigerant flow path is configured. Due to the pumping action of the gear pump 67, the refrigerant in the second flow path 31 passes through the first flow path 22, the first heat exchanger 20, the second heat exchanger 21, the expander 72 and the condenser 29, and the gear pump 67. To reflux.

A bypass refrigerant flow path 32 is connected to the first flow path 22 so as to branch from the first flow path 22. The bypass refrigerant flow path 32 is connected so as to merge with the connection flow path 25, and an electromagnetic opening / closing valve 33 is provided on the bypass refrigerant flow path 32. When the electromagnetic on-off valve 33 is excited, the bypass refrigerant flow path 32 is opened, and when the electromagnetic on-off valve 33 is demagnetized, the bypass refrigerant flow path 32 is closed.

The electromagnetic on-off valve 33 is subjected to excitation / demagnetization control by a control unit (control device) 34. A temperature detection unit 99 is connected to the control unit 34 so that signals can be transmitted. The temperature detector 99 detects the temperature of the refrigerant in the supply flow path 28 between the second heat exchanger 21 and the expander 72. In other words, the temperature detection unit 99 detects the temperature of the refrigerant in the refrigerant flow path upstream from the expander 72, that is, in the refrigerant flow path downstream from the first heat exchanger 20 and the second heat exchanger 21 and upstream from the expander 72. Is detected. The temperature detection information obtained by the temperature detection unit 99 is sent to the control unit 34, and the control unit 34 performs excitation / demagnetization control of the electromagnetic on-off valve 33 based on the temperature detection information sent from the temperature detection unit 99. When the refrigerant temperature detected by the temperature detection unit 99 becomes equal to or higher than a preset upper limit temperature To, the control unit 34 excites the electromagnetic on-off valve 33. When the refrigerant temperature detected by the temperature detection unit 99 becomes lower than the preset upper limit temperature To, the control unit 34 demagnetizes the electromagnetic on-off valve 33.

The electromagnetic on-off valve 33 functions as a refrigerant flow rate adjusting unit that adjusts the refrigerant flow rate in the bypass refrigerant flow path 32. The control unit 34 controls the flow rate adjustment state of the refrigerant flow rate adjustment unit based on the detection information of the temperature detection unit 99.

From the viewpoint of heat resistance of the seal member for preventing refrigerant leakage from the expansion chamber 78 in the expander 72, it is necessary to control the temperature of the refrigerant flowing into the expander 72 below the heat resistance temperature of the seal member. The upper limit temperature To is a value set from the viewpoint of such heat resistance. The upper limit temperature To is, for example, 150 ° C.

FIG. 3 shows the second heat exchanger 21 and the

flow path pipes

48 and 49 that are part of the exhaust flow path 15 (see FIG. 1). Exhaust gas exhausted from the engine 12 passes through the second heat exchanger 21 from the flow path pipe 48 and flows to the flow path pipe 49, and further flows to the muffler 26 (see FIG. 1).

Next, the structure of the second heat exchanger 21 will be described.

As shown in FIG. 4, the second heat exchanger 21 includes a waste heat fluid case 50 and a refrigerant header tank 58. The waste heat fluid case 50 has a waste heat fluid chamber 501 that introduces and discharges exhaust gas, which is a waste heat fluid, and the exhaust gas on the side of the flow path pipe 48 (see FIG. 3) becomes the waste heat fluid chamber 501. It flows through the flow path pipe 49 (see FIG. 3).

In the refrigerant header tank 58, a first header tank chamber 581, a second header tank chamber 582, a third header tank chamber 583, and a fourth header tank chamber 584 are formed.

The inflow pipe 60 communicates with the first header tank chamber 581, and the outflow pipe 61 communicates with the fourth header tank chamber 584. The inflow pipe 60 is a part of the connection flow path 25 (see FIG. 1), and the outflow pipe 61 is a part of the supply flow path 28 (see FIG. 1).

A large number of heat radiating plates 59 are arranged in parallel in the waste heat fluid chamber 501. Is penetrated. An end portion of the straight pipe 531 constituting the assembled pipe 551 communicates with the first header tank chamber 581. Ends of the

straight pipes

541 and 532 constituting the assembled

pipes

551 and 552 communicate with the second header tank chamber 582. Ends of the

straight pipes

542 and 533 constituting the assembled

pipes

552 and 553 communicate with the third header tank chamber 583. An end portion of the straight pipe 543 constituting the assembled pipe 553 communicates with the fourth header tank chamber 584.

The refrigerant that has flowed into the first header tank chamber 581 from the inflow pipe 60 that is a part of the connection flow path 25 flows into the second header tank chamber 582 via the assembled pipe 551. A part of the refrigerant that has flowed into the second header tank chamber 582 flows into the third header tank chamber 583 via the assembled pipe 552. The refrigerant that has flowed into the third header tank chamber 583 flows into the fourth header tank chamber 584 via the assembled pipe 553. The refrigerant that has flowed into the fourth header tank chamber 584 flows out to the outflow pipe 61 that is a part of the supply flow path 28.

As shown in FIG. 5, the second heat exchanger is provided between an exhaust inflow pipe 81 that is a part of the exhaust flow path 15 (see FIG. 1) and an exhaust outflow pipe 82 that is a part of the exhaust flow path 15. 21 and the bypass pipe 83 are provided in parallel. Inside the bypass pipe 83 is a bypass exhaust flow path 831 that bypasses the second heat exchanger 21 (waste heat fluid chamber 501). A connection plate 84 is fixed to the outlet end of the exhaust inflow pipe 81. A pair of connection holes 961 and 962 are provided through the connection plate 84. A flow path pipe 48 is fitted in the connection hole 961, and a bypass pipe 83 is fitted in the connection hole 962.

A connection plate 85 is fixed to the inlet end of the exhaust outlet pipe 82. A pair of connection holes 971 and 972 are provided through the connection plate 85. A flow path pipe 49 is fitted in the connection hole 971, and a bypass pipe 83 is fitted in the connection hole 972.

In the exhaust inflow pipe 81, the on-off valve 86 is fixed to a pivotal support shaft 87. The on-off valve 86 is switched between a closed position indicated by a solid line in FIG. 5 (a position in contact with the position restricting piece 44) and an open position indicated by a chain line in FIG. The on-off valve 86 is urged in a direction from the closed position toward the open position by a torsion spring (not shown). When the on-off valve 86 is in the closed position, the flow of exhaust gas from the exhaust inflow pipe 81 to the bypass pipe 83 is blocked. When the on-off valve 86 is in the open position, the flow of exhaust gas from the exhaust inflow pipe 81 to the bypass pipe 83 is allowed. The on-off valve 86 functions as an adjustment valve that adjusts the cross-sectional area of the bypass exhaust flow path 831.

As shown in FIG. 6, the support shaft 87 penetrates the side surface of the exhaust inflow pipe 81 and protrudes outside the exhaust inflow pipe 81. A lever 88 is fixed to the protruding end portion of the support shaft 87. A guide hole 39 is formed in the lever 88.

A temperature operating actuator 89 that controls the opening degree of the on-off valve 86 is disposed on the side of the exhaust inflow pipe 81. The temperature actuated actuator 89 includes a cylindrical housing 90, a temperature sensing cylinder 91 accommodated in the housing 90, a piston 92 slidably accommodated in the temperature sensing cylinder 91, and a temperature sensing just above the piston rod 46. And a drive rod 93 disposed in the cylinder 91. The drive rod 93 is pressed against the tip of the piston rod 46 by the spring force of the compression spring 94.

A driving pin 70 is fixed to the tip of the driving rod 93 that protrudes from the inside of the temperature-sensitive cylinder 91 to the outside. The drive pin 70 is slidably fitted in the guide hole 39 of the lever 88.

A piston 92 is plunged into the lower cylinder of the temperature sensitive cylinder 91 and a thermal expansion material 95 is filled therein. In the present embodiment, the thermal expansion material 95 is a wax that is a temperature phase transition material. The refrigerant temperature in the second header tank chamber 582 is proportional to the refrigerant temperature downstream of the second heat exchanger 21, and the refrigerant (expansion) downstream of the second heat exchanger 21 from the refrigerant temperature in the second header tank chamber 582. The temperature of the refrigerant flowing into the machine 72 can be estimated. Therefore, when the refrigerant temperature downstream of the second heat exchanger 21 reaches the predetermined temperature T1, the phase transition temperature of the thermal expansion material 95 is set so that the thermal expansion material 95 expands and the temperature operation actuator 89 operates. The predetermined temperature T1 is set to a value (To + α) higher than the upper limit temperature To. α is, for example, 5 ° C.

A refrigerant introduction chamber 96 is formed between the temperature sensing cylinder 91 and the housing 90 around the thermal expansion material 95 that constitutes the temperature sensing section together with the temperature sensing cylinder 91. The refrigerant introduction chamber 96 surrounds the thermal expansion material 95.

An introduction pipe 97 and a discharge pipe 98 are provided between the housing 90 and the refrigerant header tank 58. In the present embodiment, the introduction pipe 97 communicates the second header tank chamber 582 and the refrigerant introduction chamber 96, and the discharge pipe 98 communicates the refrigerant introduction chamber 96 and the fourth header tank chamber 584. .

The refrigerant that has flowed into the first header tank chamber 581 from the inflow pipe 60 that is a part of the connection flow path 25 flows into the second header tank chamber 582 via the assembled pipe 551 (see FIG. 4). A part of the refrigerant flowing into the second header tank chamber 582 flows into the third header tank chamber 583 via the assembled pipe 552 (see FIG. 4). The refrigerant that has flowed into the third header tank chamber 583 flows into the fourth header tank chamber 584 via the assembled pipe 553 (see FIG. 4). The refrigerant flowing into the fourth header tank chamber 584 flows out to the outflow pipe 61.

A part of the refrigerant flowing into the second header tank chamber 582 flows into the fourth header tank chamber 584 via the introduction pipe 97, the refrigerant introduction chamber 96, and the discharge pipe 98. When the temperature of the refrigerant is low, the thermal expansion material 95 hardly expands, and the piston 92 and the drive rod 93 are held at the lowest position shown in FIG. 6 by the spring force of the compression spring 94. In a state where the piston 92 and the drive rod 93 are at the lowest position, the on-off valve 86 is disposed at the closed position indicated by a broken line in FIG.

The exhaust gas exhausted from the engine 12 flows into an exhaust inflow pipe 81 that is a part of the exhaust flow path 15. In the state where the on-off valve 86 is in the closed position, the exhaust gas flowing into the exhaust inflow pipe 81 passes through the flow path pipe 48, the waste heat fluid chamber 501 (see FIG. 4) of the second heat exchanger 21, and the flow path pipe 49. To the exhaust outlet pipe 82. Accordingly, the heat of the exhaust gas is transmitted to the refrigerant through the second heat exchanger 21.

When the temperature of the refrigerant increases and the thermal expansion material 95 expands, the piston 92 and the drive rod 93 are pushed up against the spring force of the compression spring 94. The drive pin 70 moving upward together with the drive rod 93 pushes up the lever 88 while moving in the guide hole 39. The upward movement of the lever 88 turns the support shaft 87 and the opening / closing valve 86 in the counterclockwise direction in FIG. Thereby, the on-off valve 86 moves toward the open position shown by the two-dot chain line in FIG.

The temperature actuated actuator 89 and the on-off valve 86 constitute a gas flow rate adjusting unit that adjusts the exhaust gas flow rate by changing the cross-sectional area of the bypass exhaust flow channel 831.

Next, the operation of the first embodiment will be described.

The refrigerant sent to the first flow path 22 by the action of the gear pump 67 is the heat absorption part 202 of the first heat exchanger 20, the connection flow path 25, the refrigerant header tank 58 of the second heat exchanger 21, and the assembled

pipes

551 and 552. , 553 and sent to the supply flow path 28. The refrigerant passing through the heat absorption part 202 of the first heat exchanger 20 is heated by the heat of the cooling water that has cooled the engine 12. The refrigerant passing through the assembled

pipes

551, 552, 553 of the second heat exchanger 21 is heated by the heat of the exhaust gas discharged from the engine 12.

The high-pressure refrigerant heated by the

heat exchangers

20 and 21 is introduced from the introduction port 381 through the supply chamber 79 of the expander 72 into the expansion chamber 78 and expands. The expansion of the refrigerant causes the expander 72 to output mechanical energy (rotation imparting force), and the rotation imparting force assists the rotation of the rotating shaft 40. The refrigerant whose pressure has decreased due to expansion is discharged to the discharge flow path 30. The refrigerant discharged to the discharge passage 30 passes through the condenser 29 and returns to the gear pump 67.

When the refrigerant temperature detected by the temperature detection unit 99 is equal to or higher than the preset upper limit temperature To, the control unit 34 excites the electromagnetic on-off valve 33. As a result, the electromagnetic opening / closing valve 33 is opened, and a part of the refrigerant sent out from the gear pump 67 flows into the bypass refrigerant flow path 32. That is, a part of the refrigerant sent out from the gear pump 67 bypasses the first heat exchanger 20. As a result, the amount of heat transferred from the first heat exchanger 20 to the refrigerant decreases, and the temperature of the refrigerant flowing into the expander 72 decreases. When the refrigerant temperature detected by the temperature detection unit 99 becomes lower than the preset upper limit temperature To, the control unit 34 demagnetizes the electromagnetic on-off valve 33. Thereby, the electromagnetic on-off valve 33 is closed, and all the refrigerant sent out from the gear pump 67 passes through the first heat exchanger 20.

Part of the refrigerant that has flowed into the second header tank chamber 582 of the second heat exchanger 21 flows into the fourth header tank chamber 584 via the introduction pipe 97, the refrigerant introduction chamber 96, and the discharge pipe 98. When the temperature of the refrigerant is low, the thermal expansion material 95 hardly expands, and the piston 92 and the drive rod 93 are held at the lowest position shown in FIG. 6 by the spring force of the compression spring 94. In a state where the piston 92 and the drive rod 93 are at the lowest position, the compression spring 94 is disposed at the closed position indicated by a broken line in FIG.

The exhaust gas exhausted from the engine 12 flows into an exhaust inflow pipe 81 that is a part of the exhaust flow path 15. In the state where the on-off valve 86 is in the closed position, the exhaust gas flowing into the exhaust inflow pipe 81 flows out through the flow path pipe 48, the waste heat fluid chamber 501 of the second heat exchanger 21 and the flow path pipe 49. Flow to tube 82. Accordingly, the heat of the exhaust gas is transmitted to the refrigerant through the second heat exchanger 21.

When the refrigerant temperature downstream of the second heat exchanger 21 reaches the predetermined temperature T1, the thermal expansion material 95 expands. Due to the expansion of the thermal expansion material 95, the on-off valve 86 moves to the open position indicated by a two-dot chain line in FIG.

When the on-off valve 86 is in the open position, most of the exhaust gas flowing into the exhaust inflow pipe 81 flows to the exhaust outflow pipe 82 via the bypass exhaust flow path 831 in the bypass pipe 83. Therefore, the amount of heat transferred from the high-temperature exhaust gas to the refrigerant via the second heat exchanger 21 is reduced, and even when the exhaust gas is at an abnormally high temperature, overheating of the refrigerant is suppressed.

The following advantages are obtained in the first embodiment.

(1) When the temperature of the refrigerant flowing into the expander 72 becomes equal to or higher than a preset upper limit temperature To, the control unit 34 controls the electromagnetic on-off valve 33 to be in an open state so that the refrigerant flows into the bypass refrigerant flow path 32. . As a result, the amount of heat transferred from the cooling water to the refrigerant is reduced, and waste heat generated in the engine 12 is accumulated in the cooling water. When the temperature of the refrigerant flowing into the expander 72 becomes lower than the upper limit temperature To, all the refrigerant sent out from the gear pump 67 passes through the first heat exchanger 20, and the heat accumulated in the cooling water is transmitted to the refrigerant. The

When there is no bypass refrigerant flow path 32, the heat of the cooling water is always transmitted to the refrigerant when the temperature of the cooling water is lower than the temperature of the refrigerant, so the temperature of the refrigerant flowing into the second heat exchanger 21 is high. Become. In that case, the amount of exhaust gas that can flow into the second heat exchanger 21 is reduced, and waste heat is wasted. However, in the present invention having the bypass refrigerant flow path 32, the waste heat of the engine 12 can be accumulated in the cooling water, and the accumulated heat is such that the temperature of the refrigerant flowing into the expander 72 is lower than the upper limit temperature To. Can be used for power generation in the alternator 43. Therefore, the efficiency of waste heat utilization in the waste heat recovery apparatus 11 having the expander 72 connected to the engine 12 so that the driving force is transmitted from the engine 12 that outputs the rotational driving force is improved.

(2) If the temperature of the refrigerant flowing into the expander 72 is equal to or higher than the predetermined temperature T1 exceeding the upper limit temperature To even if a part of the refrigerant is bypassed to the bypass refrigerant flow path 32, the temperature of the refrigerant is increased. A temperature-actuating actuator 89 that operates autonomously in response is activated. As a result, the exhaust gas is allowed to flow into the bypass exhaust flow path 831 and the temperature of the refrigerant can be suppressed so as not to greatly exceed the upper limit temperature To.

(3) The temperature operation actuator 89 that operates autonomously in response to the temperature of the refrigerant is simple as a gas flow rate adjustment unit.

Next, the second embodiment of FIG. 7 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.

On the first flow path 22 between the branch section 100 between the first flow path 22 and the bypass refrigerant flow path 32 and the first heat exchanger 20, an electromagnetic on-off valve 33A is provided. Based on the temperature detection information sent from the temperature detection unit 99, the control unit 34 performs excitation / demagnetization control on the electromagnetic on-off valve 33A. When the refrigerant temperature detected by the temperature detection unit 99 becomes equal to or higher than a preset upper limit temperature To, the control unit 34 excites the electromagnetic on-off valve 33A. When the refrigerant temperature detected by the temperature detection unit 99 becomes lower than the preset upper limit temperature To, the control unit 34 demagnetizes the electromagnetic on-off valve 33A.

The electromagnetic on-off valve 33 opens when energized and closes when demagnetized, while the electromagnetic on-off valve 33A closes when energized and opens when demagnetized. That is, when the refrigerant temperature detected by the temperature detection unit 99 becomes equal to or higher than the upper limit temperature To, the electromagnetic on-off valve 33 is opened, the electromagnetic on-off valve 33A is closed, and all of the refrigerant sent from the gear pump 67 is the first heat exchanger. It bypasses 20 and flows through the bypass refrigerant flow path 32.

The electromagnetic on-off valve 33 and the electromagnetic on-off valve 33A function as a flow path switching unit that allows the refrigerant to flow through only one of the first heat exchanger 20 and the bypass refrigerant flow path 32.

The configuration in which the refrigerant flows only through the bypass refrigerant flow path 32 and does not flow through the first heat exchanger 20 is optimal in increasing the amount of heat stored in the cooling water circulation path 23. In other words, the configuration in which the refrigerant flows only through the bypass refrigerant flow path 32 and does not flow through the first heat exchanger 20 is optimal for increasing the upper limit temperature of the cooling fluid in consideration of the reliability of the expander 72. is there.

In the present invention, the following embodiments are also possible.

In the first embodiment, instead of the electromagnetic on-off valve 33, an adjustment valve whose flow rate is continuously variable may be used.

In the second embodiment, an electromagnetic three-way valve may be provided at the branch portion 100 between the first flow path 22 and the bypass refrigerant flow path 32 instead of the electromagnetic on-off

valves

33 and 33A. In this case, the electromagnetic three-way valve causes all the refrigerant to flow to the bypass refrigerant flow path 32 when excited, and causes all the refrigerant to flow to the first heat exchanger 20 when demagnetized.

A gas flow rate adjusting unit in which the on-off valve 86 is driven by an electric motor may be used. In this case, the operation of the electric motor is controlled based on the temperature detection information of the temperature detection unit 99.

The bypass exhaust flow path 831 and the gas flow rate adjustment unit may be omitted.

A pump that pumps the refrigerant that has passed through the condenser 29 may be provided outside the waste heat recovery device 14.

The present invention may be applied to a waste heat recovery device other than for vehicles.

As the expander, a vane type expander may be used.

Claims

A waste heat recovery device that recovers waste heat generated in a combustion engine that outputs rotational driving force,
A first heat exchanger that transfers heat of a cooling fluid that cools the combustion engine to a refrigerant;
A second heat exchanger that transfers heat of the exhaust gas discharged from the combustion engine to the refrigerant;
An expander coupled to the combustion engine such that driving force is transmitted from the combustion engine;
A refrigerant flow path through which the refrigerant passes;
A bypass refrigerant flow path that branches from the refrigerant flow path and bypasses the first heat exchanger;
A refrigerant flow rate adjusting unit for adjusting a refrigerant flow rate in the bypass refrigerant flow path;
A temperature detector for detecting a refrigerant temperature in the refrigerant flow channel upstream of the expander;
A control unit for controlling a flow rate adjustment state of the refrigerant flow rate adjustment unit based on detection information of the temperature detection unit;
A waste heat recovery device.
The combustion engine has an exhaust passage through which exhaust gas discharged from the engine passes, and the waste heat recovery device includes:
A bypass exhaust passage that branches off from the exhaust passage and bypasses the second heat exchanger;
A gas flow rate adjusting unit for adjusting an exhaust gas flow rate in the bypass exhaust flow path;
The waste heat recovery apparatus according to claim 1, further comprising:
The gas flow rate adjustment unit includes an adjustment valve that adjusts a cross-sectional area of the bypass exhaust passage, and a temperature-actuated actuator that controls an opening degree of the adjustment valve,
The waste heat recovery apparatus according to claim 2, wherein the temperature-actuated actuator has a temperature-sensitive part that is sensitive to the temperature of the refrigerant after receiving heat by the second heat exchanger.
The said refrigerant | coolant flow volume adjustment part is a flow-path switching part which flows a refrigerant | coolant only in any one of a said 1st heat exchanger and the said bypass refrigerant | coolant flow path. Waste heat recovery device.
The waste heat recovery apparatus according to any one of claims 1 to 3, wherein the refrigerant flow rate adjusting unit is an on-off valve provided on the bypass refrigerant flow path.
A pump that pumps the refrigerant that has passed through the condenser;
The waste heat recovery apparatus according to any one of claims 1 to 3, wherein the pump is directly connected to a rotation shaft of the expander.