JP2008231980A - Waste heat utilization device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste heat utilization device for an internal combustion engine capable of enhancing the waste heat recovery efficiency of the internal combustion engine while advancing the warmup of the internal combustion engine by a simple structure. <P>SOLUTION: This waste heat utilization device 2 for recovering the waste heat of the internal combustion engine 4 from heat media comprises, in addition to a heat exchanger 24 for exchanging heat between a working fluid heated by the exchange of heat between itself and a low temperature heat medium and a high temperature heat medium and further heating the working fluid, and a Rankine cycle circuit 8 having an expander 28; a condenser 30; and pumps 22, 34 and forming a Rankine cycle path 40 by circulating the working fluid between an energy generating circuit part 38 and a heat exchange circuit part 42. The Rankine cycle circuit comprises a bypass path 36 bypassing the energy generating circuit part, and a path changing means for changing the path to the bypass path according to the operating state of the internal combustion engine, and changing a Rankine cycle path to a heat pipe path 44. The pumps are so disposed as to circulate a liquid working fluid irrespective of whether or not the path is changed by the path changing means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine waste heat utilization device, and more particularly to an internal combustion engine waste heat utilization device suitable for a vehicle.

As a waste heat utilization device for an internal combustion engine, for example, in a vehicle engine, the exhaust gas heat exhausted from the engine is recovered, and the recovered exhaust gas heat is used to heat the cooling water in the engine cooling water circuit to heat the engine. A Rankine cycle circuit that shortens the time required to warm up the engine is known (see, for example, Patent Document 1).
JP 2005-42618 A

However, the above prior art has a problem that the waste heat recovery efficiency of the Rankine cycle is lowered.
This is because a liquid refrigerant needs to flow into a pump driven to circulate a working fluid (hereinafter referred to as a refrigerant) in a Rankine cycle circuit in order to prevent cavitation and the like. Then, the heat exchanger that performs heat exchange between the engine coolant circuit and the Rankine cycle circuit functions only as a condenser that condenses the refrigerant both when the waste heat is recovered and when the engine is warmed up.

That is, in the Rankine cycle circuit of the prior art, exhaust gas heat can be recovered at the time of waste heat recovery, but waste heat of the engine body cannot be recovered.
In addition, an air-cooled condenser is installed downstream of the expander in the Rankine cycle circuit to condense the refrigerant in front of the heat exchanger, and this heat exchanger functions as an evaporator to recover waste heat from the engine body. It is also possible to do. However, if the refrigerant heated by the engine cooling water evaporates, it cannot be circulated by the pump, and in any case, the waste heat of the engine body cannot be recovered.

  The present invention has been made in view of such problems, and provides a waste heat utilization device for an internal combustion engine that can improve the waste heat recovery efficiency of the internal combustion engine while speeding up the warm-up of the internal combustion engine with a simple configuration. With the goal.

  In order to achieve the above object, a waste heat utilization apparatus for an internal combustion engine according to claim 1 is a waste heat utilization apparatus for recovering heat from a plurality of heat mediums, wherein the heat medium has a predetermined temperature. A heat exchanger that includes a high-temperature heat medium having waste heat and a low-temperature heat medium having waste heat that is lower than a predetermined temperature, and heats the working fluid that has exchanged heat with the low-temperature heat medium by exchanging heat with the high-temperature heat medium. An internal combustion engine and a heat exchanger having an expander that expands the working fluid that passes through the heat exchanger to generate a driving force, a condenser that condenses the working fluid that passes through the expander, and a pump that circulates the working fluid A Rankine cycle in which a heat exchange circuit unit is formed from an expander and a condenser, and a working fluid is circulated between the energy generation circuit unit and the heat exchange circuit unit by a pump to form a Rankine cycle path. With circuit and run The cycle circuit has a bypass path that bypasses the energy generation circuit section, and the heat exchange circuit section is heated by a pump to heat the low-temperature heat medium with the working fluid heated and evaporated by the heat exchanger by switching the circuit to the bypass path. In addition, the working fluid is circulated in the bypass path to form a heat pipe path, and the circuit is switched to the bypass path according to the operation state of the internal combustion engine, and the path switching is performed to switch between the Rankine cycle path and the heat pipe path. And the pump is arranged to circulate the liquid working fluid regardless of the path switching by the path switching means.

  According to a second aspect of the present invention, in the first aspect, the pump is disposed between the energy generation circuit unit and the heat exchange circuit unit to direct the working fluid from the energy generation circuit unit to the heat exchange circuit unit. The Rankine cycle circuit includes a first pump that circulates and a second pump that circulates the working fluid that has exchanged heat with the low-temperature heat medium toward the heat exchanger. And a second pump bypass passage for bypassing the two pumps, and the path switching means controls the operation of the first pump and the second pump with the means for switching the circuit to the first pump bypass path and the second pump bypass path. When the Rankine cycle path is formed, the first pump bypass path is closed and the first pump is driven, while the second pump bypass path is opened and the second pump is stopped. , During formation of the heat pipe route, while stopping the first pump and opens the first pump bypass passage is characterized by driving the second pump by closing the second pump bypass passage.

  Further, in the invention according to claim 3, in claim 1, the pump is disposed between the energy generation circuit unit and the heat exchange circuit unit, and the Rankine cycle circuit includes the energy generation circuit unit, the suction port of the pump, A first communication passage that communicates with the first communication passage, a second communication passage that communicates between the discharge port of the pump and the heat exchange circuit in conjunction with the first communication passage, and a third communication that communicates between the heat exchange circuit and the suction port of the pump. A four-way valve comprising a fourth communication passage that communicates the discharge port of the pump and the bypass passage in conjunction with the passage and the third communication passage, the path switching means includes means for switching control of the four-way valve, and the Rankine cycle path When the heat pipe path is formed, the third communication path and the fourth communication path of the four-way valve are closed to connect the first communication path and the second communication path, while when the heat pipe path is formed, the first communication path of the four-way valve is formed. And the second communication passage are closed to make the third communication It is characterized by communicating the fourth communication passage when.

  Furthermore, in the invention of claim 4, in claim 2 or 3, the low-temperature heat medium is cooling water that exchanges heat with the internal combustion engine, and a cooling water circuit in which the cooling water that circulates through the internal combustion engine circulates, A second heat exchanger that is inserted in the water circuit and exchanges heat with the working fluid before reaching the heat exchanger, and a second bypass path that constitutes the cooling water circuit and bypasses the second heat exchanger The path switching means includes means for switching the circuit of the cooling water circuit to the second bypass path, and is characterized in that the circuit is held on the second heat exchanger side when the heat pipe path is formed.

Further, in the invention described in claim 5, in claim 2 or 3, the low temperature heat medium is the same fluid as the working fluid circulating in the Rankine cycle circuit, and the working fluid directly takes waste heat of the internal combustion engine. It is a feature.
Furthermore, the invention according to claim 6 further comprises a temperature sensor for detecting the temperature of the working fluid according to claim 5, wherein the path switching means rotates the pump according to the temperature of the working fluid detected by the temperature sensor. It includes means for controlling the number and the load on the expander.

According to the waste heat utilization apparatus for an internal combustion engine of the first aspect of the present invention, the Rankine cycle circuit includes a heat exchange circuit unit and an energy generation circuit unit, and these circuit units are driven by driving a pump. The working fluid circulates between them. And the heat pipe path | route which consists only of a heat exchange circuit part is formed by bypassing an energy generation circuit part with a path | route switching means.
Here, since the pump is arranged to circulate the liquid working fluid regardless of the switching of the path by the path switching means, when the Rankine cycle path is formed, the pump ensures that the working fluid is passed through the Rankine cycle path. The working fluid flowing into the heat exchanger can be well heated in advance by the low-temperature heat medium, and waste heat recovery can be actively performed not only from the high-temperature heat medium but also from the low-temperature heat medium.

On the other hand, when the heat pipe path is formed, the working fluid can be reliably circulated in the heat pipe path by the pump, and the circuit as the heat pipe for heating the cooling water by the working fluid heated and evaporated by the heat exchanger can be smoothly smoothed. Can function.
Therefore, it is possible to improve the waste heat recovery efficiency of the internal combustion engine while speeding up the warm-up of the internal combustion engine with a simple configuration by reliably circulating the refrigerant in both cases of forming the Rankine cycle path and forming the heat pipe path.

  According to the second aspect of the present invention, the pump is disposed between the energy generation circuit unit and the heat exchange circuit unit and circulates the working fluid from the energy generation circuit unit to the heat exchange circuit unit. 1 pump and a second pump that circulates the working fluid heat-exchanged with the low-temperature heat medium toward the heat exchanger, and the Rankine cycle circuit includes a first pump bypass path and a second pump that bypass the first pump. A second pump bypass path for bypassing, and when the Rankine cycle path is formed, the path switching means closes the first pump bypass path and drives the first pump, while opening the second pump bypass path. Then, the second pump is stopped, and when the heat pipe path is formed, the first pump bypass path is opened to stop the first pump, while the second pump bypass path is closed to drive the second pump. I have to so that. Accordingly, it is possible to reliably circulate the liquid working fluid with the first pump or the second pump regardless of the path switching, and to improve the waste heat recovery efficiency of the internal combustion engine while speeding up the warming up of the internal combustion engine.

  According to a third aspect of the present invention, the pump is disposed between the energy generation circuit unit and the heat exchange circuit unit, and the Rankine cycle circuit communicates the energy generation circuit unit with the suction port of the pump. A first communication path, a second communication path that communicates the discharge port of the pump and the heat exchange circuit unit in conjunction with the first communication path, and a third communication path that communicates the heat exchange circuit unit and the suction port of the pump. And a four-way valve comprising a fourth communication passage that communicates the discharge port of the pump and the bypass passage in conjunction with the third communication passage, and the path switching means includes a third one of the four-way valves when the Rankine cycle path is formed. The communication path and the fourth communication path are closed to connect the first communication path and the second communication path, while the first communication path and the second communication path of the four-way valve are closed when the heat pipe path is formed. So that the third communication path and the fourth communication path communicate with each other. That. As a result, the existing pump that circulates between the heat exchange circuit unit and the energy generation circuit unit circuit unit is used, and a simplified circuit configuration in which a new four-way valve is newly provided. It is possible to improve the waste heat recovery efficiency of the internal combustion engine while speeding up the warming up of the internal combustion engine by reliably circulating the working fluid with a pump.

  Furthermore, according to the invention described in claim 4, the low-temperature heat medium is cooling water that exchanges heat with the internal combustion engine, the cooling water circuit through which the cooling water passes through the internal combustion engine circulates, and the cooling water circuit. A second heat exchanger that exchanges heat with the working fluid before reaching the heat exchanger, and a second bypass path that constitutes a cooling water circuit and bypasses the second heat exchanger, The path switching means includes means for switching the circuit of the cooling water circuit to the second bypass path, and holds the circuit on the second heat exchanger side when the heat pipe path is formed. Thereby, since the cooling water can be passed through the second heat exchanger as much as possible when the heat pipe path is formed, it is possible to further accelerate the warm-up of the internal combustion engine.

  According to the invention described in claim 5, since the low-temperature heat medium is the same fluid as the working fluid circulating in the Rankine cycle circuit, the working fluid can directly exchange heat with the main body of the internal combustion engine. As a result, the heat transfer efficiency of the Rankine cycle circuit can be improved, so that further rapid warm-up of the internal combustion engine and improvement of the waste heat recovery efficiency can be realized, and the circuit configuration can be simplified.

  Furthermore, according to the invention described in claim 6, the temperature sensor for detecting the temperature of the working fluid directly charged with the waste heat of the internal combustion engine is further provided, and the path switching means has a temperature of the working fluid detected by the temperature sensor. Correspondingly, means for controlling the rotational speed of the pump and the load of the expander is included. Here, the amount of waste heat recovered and the amount of waste heat used in the Rankine cycle circuit can be calculated according to the rotational speed of the pump and the load on the expander, respectively. By controlling the amount of waste heat recovered and the amount of waste heat used, the body temperature of the internal combustion engine can be kept substantially constant at a desired temperature even when the working fluid directly exchanges heat with the body of the internal combustion engine. The Rankine cycle circuit can be made to function more appropriately.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
FIG. 1 is a schematic diagram showing a configuration of a waste heat utilization device 2 for an internal combustion engine according to the present embodiment. The waste heat utilization device 2 is a cooling system that circulates cooling water and cools, for example, an engine (internal combustion engine) 4 of a vehicle. A water circuit 6 and a Rankine cycle circuit 8 (hereinafter referred to as cycle 8) that circulates a working fluid (hereinafter referred to as refrigerant) and recovers waste heat of the engine 4 are configured.

  In the cooling water circuit 6, a water pump 10, a heat exchanger (second heat exchanger) 12, and a thermostat 14 are connected in order from the engine 4 to form a closed circuit, and the thermostat 14 bypasses the heat exchanger 12. A path 16 is connected, and an electromagnetic valve 18 is inserted in the bypass path 16. Then, by driving the water pump 10, the cooling water flows and circulates through each of the constituent devices.

Further, the engine 4 is equipped with a temperature sensor 20 for detecting the coolant temperature after flowing out of the engine 4, and according to the detected coolant temperature, waste heat recovery of the engine 4 is performed, or It is determined whether a warm-up request is made immediately after the engine 4 is started.
The water pump 10 is a linear electric pump, and the amount of cooling water circulating in the cooling water circuit 6 is reduced by continuously driving the movable portion in proportion to an input signal input to the driving portion of the water pump 10. It is configured to allow fine adjustment. Specifically, it is driven according to the rotational speed of the engine 4, and the amount of cooling water required for cooling the engine 4 is circulated to the cooling water circuit 6.

The heat exchanger 12 functions as an evaporator that evaporates the refrigerant when the waste heat of the engine 4 is recovered and absorbs heat on the cycle 8 side by exchanging heat with the refrigerant flowing through the cycle 8, and the refrigerant when the engine 4 is requested to warm up. It functions as a condenser that condenses and heats from the cycle 8 side.
The thermostat 14 is a mechanical switching valve having a temperature detection unit (not shown) built therein and having two inlet ports and one outlet port. Then, depending on the coolant temperature detected by the temperature detector, either the inlet port to which the flow path on the heat exchanger 12 side is connected or the inlet port to which the bypass path 16 is connected communicates. By switching or finely adjusting the valve body, whether or not to allow the cooling water to flow through the heat exchanger 12 is appropriately selected, and the amount of cooling water to be passed is finely adjusted, and the body temperature of the engine 4 is set to a predetermined value. The temperature is kept almost constant.

The electromagnetic valve 18 is driven in response to a signal from the temperature sensor 20, and is opened when the waste heat is recovered to allow the thermostat 14 to function properly, and is kept closed when a warm-up is requested (path switching means).
On the other hand, in the cycle 8, the heat exchanger 12 to the exhaust gas heat exchanger (heat exchanger) 24, the three-way valve 26, the expander 28, the condenser 30, the check valve 32, the refrigerant pump (pump, first pump) 22. Are connected in order to form a closed circuit, and a second refrigerant pump (pump, second pump) 34 is provided between the heat exchanger 12 and the exhaust gas heat exchanger 24.

A bypass path 36 is provided between the three-way valve 26 and the check valve 32 and the refrigerant pump 22 to bypass the expander 28, the condenser 30, and the check valve 32.
The refrigerant pump 22 and the second refrigerant pump 34 are electric pumps that drive the movable portion in accordance with contact signals input to the drive portions of the pumps 22 and 34, and appropriately circulate the refrigerant in the cycle 8.

The exhaust gas heat exchanger 24 is provided in an exhaust gas pipe (not shown) through which the exhaust gas (high temperature heat medium) of the engine 4 flows out, and at the time of waste heat recovery, the refrigerant heated by the cooling water in the heat exchanger 12 is further heated by the exhaust gas. The waste heat of the engine 4 is recovered from both the main body of the engine 4 and the exhaust gas.
On the other hand, when the engine 4 is requested to warm up, the exhaust gas heat exchanger 24 functions as an evaporator that heats and evaporates the cooling water circulating in the cooling water circuit 6 via the heat exchanger 12 by switching the refrigerant path in the cycle 8. .

  Specifically, the three-way valve 26 is an on / off switching valve having one inlet port and two outlet ports, and the flow path on the side of the expander 28 according to a contact signal input to the drive unit of the three-way valve 26. The valve body is switched so that the inlet port communicates with either the outlet port connected to the outlet port or the outlet port connected to the bypass path 36. Thus, it is possible to select whether or not the refrigerant is allowed to flow through the expander 28 and the condenser 30, that is, the energy generation circuit unit 38, and when the waste heat of the engine 4 is recovered, the Rankine cycle path 40 ( Hereinafter, the Rankine path 40 is closed.

On the other hand, when the engine 4 is required to warm up, the energy generation circuit unit 38 is bypassed, and the heat including the heat exchanger 12 and the exhaust gas heat exchanger 24, which are the constituent devices of the remaining cycle 8, is the heat including only the heat exchange circuit unit 42. The pipe path 44 (hereinafter referred to as the heat path 44) is closed, and the exhaust gas heat exchanger 24 functions as an evaporator as described above.
The expander 28 is a fluid device that generates a driving force related to rotation or the like by expansion of a refrigerant that is heated by the heat exchanger 12 and the exhaust gas heat exchanger 24 and becomes a superheated steam state. Further, for example, a generator (not shown) is connected to the expander 28, and the driving force generated by the expander 28 via this generator can be used outside the waste heat utilization apparatus 2.

  The condenser 30 is a heat exchanger that condenses and liquefies the refrigerant discharged from the expander 28 by heat exchange with the outside air, and the liquid refrigerant that is reliably condensed by the condenser 30 is transferred to the heat exchanger 12 by the refrigerant pump 22. Pumped and suitably circulated through Rankine path 40 or heat path 44 constituting cycle 8. The check valve 32 prevents the refrigerant from flowing backward to the condenser 30 when the heat path 44 is formed.

  By the way, in the waste heat utilization apparatus 2 of this embodiment, pump switching control is implemented so that the refrigerant pump 22 and the second refrigerant pump 34 can be individually used in the Rankine path 40 and the heat path 44, respectively. Specifically, the cycle 8 includes a bypass path (first pump bypass path) 46 and a bypass path (second pump bypass path) 48 that bypass the pumps 22 and 34 respectively. Electromagnetic valves 50 and 52 are inserted, and the pumps 22 and 34 are driven and stopped simultaneously with opening and closing of the electromagnetic valves 50 and 52.

  More specifically, when the Rankine path 40 is formed, the refrigerant pump 22 is driven and the electromagnetic valve 50 is closed, while the second refrigerant pump 34 is stopped and the electromagnetic valve 52 is opened. In FIG. 1, not only the solenoid valves 50 and 52 but also the white ports of the solenoid valve 18 and the three-way valve 26 indicate fully opened ports, and the blacked ports indicate fully closed ports. Is shown in the same way.

In contrast, when the heat path 44 shown in FIG. 2 is formed, the second refrigerant pump 34 is driven and the electromagnetic valve 52 is closed, while the refrigerant pump 22 is stopped and the electromagnetic valve 50 is opened.
Here, the temperature sensor 20 serving as the detection end, the solenoid valves 18, 50, 52 serving as the operation end, the three-way valve 26, and the pumps 10, 22, and 34 are electronic devices that perform comprehensive control of the vehicle and the waste heat utilization device 2. It is electrically connected to a control unit (ECU) 54, and pump switching control is processed in this ECU 54.

  Specifically, it is determined whether or not there is a request for warming up the engine 4 according to the coolant temperature detected by the temperature sensor 20, and the three-way valve 26 switches the path between the Rankine path 40 and the heat path 44. Is implemented. At this time, pump switching control including opening and closing of the electromagnetic valve 18 is also performed at substantially the same timing, so that the refrigerant flow after the path switching between the paths 40 and 44 is not unnecessarily obstructed (path switching means). ).

  As described above, in the present embodiment, the Rankine cycle circuit is configured to include the energy generation circuit unit 38 and the heat exchange circuit unit 42, and by driving the refrigerant pump 22, the circuit unit 38 is connected between the circuit units 38 and 42. The refrigerant circulates. When the cooling water temperature detected by the temperature sensor 20 decreases and the engine 54 is required to be warmed up in the ECU 54, the three-way valve 26 is driven to bypass the energy generation circuit unit 38, and the pump switching control is performed. Is performed, and the refrigerant pump 22 is stopped and bypassed, while the second refrigerant pump 34 is driven to release the bypass, and the heat path 44 including only the heat exchange circuit unit 42 is formed.

Here, since the refrigerant pump 22 is positioned between both the circuit portions 38 and 42, when the Rankine path 40 is formed, the refrigerant flowing into the exhaust gas heat exchanger 24 is cooling water heated by heat absorption from the engine 4, that is, so-called It is preheated with warm water (low temperature heat medium), and waste heat can be recovered not only from the exhaust gas but also from this warm water.
On the other hand, when the heat path 44 is formed, the refrigerant pump 22 is bypassed by the pump switching control, so that the refrigerant heated and evaporated by the exhaust gas heat exchanger 24 smoothly and sequentially passes through the bypass paths 36 and 46. Flow into. That is, when the heat path 44 is formed, the refrigerant pump 22 is prevented from becoming a pressure loss factor of the superheated refrigerant, and the superheated refrigerant that has passed through the refrigerant pump 22 is not condensed.

And the refrigerant | coolant which passed through the heat exchanger 12 is absorbed and condensed by heating the cooling water which circulates through the cooling water circuit 6, and by extension, the main body of the engine 4. FIG. The condensed liquid refrigerant is pumped to the exhaust gas heat exchanger 24 by the second refrigerant pump 34, and the refrigerant is suitably circulated in the heat path 44.
In the cooling water circuit 6, the electromagnetic valve 18 is driven in response to a signal from the temperature sensor 20 and is opened when waste heat is recovered, that is, when the Rankine path 40 is formed, so that the thermostat 14 functions properly. When requested, that is, when the heat path 44 is formed, the valve is held closed. Thereby, cooling water can be passed through the heat exchanger 12 as much as possible. Therefore, regardless of whether the Rankine path 40 is formed or the heat path 44 is formed, the refrigerant is reliably circulated in the cycle 8, and the warm-up of the engine 4 can be speeded up with a simple configuration. Waste heat recovery efficiency can be improved.

Next, a second embodiment will be described.
As shown in FIG. 3, the waste heat utilization device 56 of the second embodiment excludes the cooling water circuit 6 and its components and the heat exchanger 12 of the first embodiment and circulates in the cycle 8. Is directly exchanged with the engine 4, and the other configuration is the same as that of the first embodiment, so that the differences will be mainly described.

FIG. 3 shows the time when the Rankine path 40 is formed, in which the refrigerant circulating in the cycle 8 is introduced into the engine 4 and the waste heat is recovered directly from the main body of the engine 4 without passing through the cooling water.
On the other hand, when the ECU 4 requires the engine 4 to be warmed up, the three-way valve 26 is switched to bypass the energy generation circuit unit 38 and the pump switching control is performed to form the heat path 44 (state illustration is omitted). ), The refrigerant that has been overheated by the exhaust gas heat exchanger 24 is introduced into the engine 4, and the main body of the engine 4 is directly heated to warm up without passing through the cooling water.

In this embodiment, the temperature sensor 20 detects the refrigerant temperature after flowing out of the engine 4, and the ECU 54 determines the rotation speed and expansion of the pump 22 according to the refrigerant temperature detected by the temperature sensor 20. The load of the machine 28 is controlled (path switching means).
As described above, in the waste heat utilization apparatus 56 according to the second embodiment as well, the cycle 8 is started from the main body of the engine 4 when the Rankine path 40 is formed by performing the pump switching control. In addition, the waste heat can be positively recovered and can function smoothly as a heat pipe for heating the main body of the engine 4 when the heat path 44 is formed.

In particular, in the case of the second embodiment, since the cooling water circuit 6 is not required and heat is directly exchanged with the main body of the engine 4 without passing through the cooling water, the heat transfer efficiency of the cycle 8 is greatly improved. As a result, the engine 4 can be warmed up more quickly and waste heat recovery efficiency can be improved, and the circuit configuration can be further simplified.
Further, since the amount of waste heat recovered and the amount of waste heat used in the cycle 8 can be calculated based on the rotation speed of the pump 22 and the load of the expander 28, respectively, the pump 22 depends on the refrigerant temperature detected by the temperature sensor 20. By controlling the rotation speed and the load of the expander 28, the body temperature of the engine 4 can be kept substantially constant at a predetermined temperature instead of the thermostat 14 in the first embodiment.

Next, a third embodiment will be described.
As shown in FIG. 4, the waste heat utilization device 58 of the third embodiment excludes the second refrigerant pump 34, the bypass passages 46 and 48, and the electromagnetic valves 50 and 52 of the second embodiment, and instead The four-way valve 60 is installed, and the valve drive control of the four-way valve 60 is performed instead of the pump switching control. The rest of the configuration is the same as that of the second embodiment, and the differences are mainly described. To do.

  As shown in FIG. 4, the four-way valve 60 is an on / off switching valve having first to fourth communication passages 60 a to 60 d, and its drive unit is electrically connected to the ECU 54, and the ECU 54 connects to the drive unit. In accordance with the input contact signal, the valve body is arranged so that one of the first and second communication passages 60a and 60b, or the third and fourth communication passages 60c and 60d, which are arranged symmetrically with each other, communicates. Switch. Thus, the opening of the Rankine path 40 and the opening of the heat path can be selected.

  Specifically, FIG. 4 shows the time when the Rankine path 40 is formed. In this state, the first communication path 60a communicates the condenser 30 and the refrigerant pump 22, and the second communication path 60b communicates with the refrigerant pump 22 and the engine. The refrigerant circulating in the cycle 8 is introduced into the engine 4 via the four-way valve 60 and the refrigerant pump 22 to recover waste heat directly from the main body of the engine 4. Yes.

On the other hand, as shown in FIG. 5, when the ECU 54 requests the engine 4 to be warmed up, the three-way valve 26 is switched to bypass the energy generation circuit unit 38 and the four-way valve 60 is controlled to be driven. A path 44 is formed, and the refrigerant that has been overheated by the exhaust gas heat exchanger 24 is introduced into the engine 4, and the main body of the engine 4 is directly heated to warm up.
In this state, the third communication path 60c communicates the engine 4 and the refrigerant pump 22, and the fourth communication path 60d is driven to communicate the refrigerant pump 22 and the exhaust gas heat exchanger 24. In this embodiment, the refrigerant flow direction in the heat path 44 is opposite to the refrigerant flow direction in the Rankine path 40.

As described above, in the waste heat utilization apparatus 58 according to the third embodiment as well, the engine 4 is appropriately cooled by performing the valve drive control of the four-way valve 60 instead of the pump switching control. However, the circuit configuration of the cycle 8 can be simplified, and the engine 4 can be warmed up more quickly and the waste heat recovery efficiency can be improved.
Particularly in the case of the third embodiment, the heat exchange circuit unit 42 and the energy generation circuit unit are not required without the need for the second refrigerant pump 34, the bypass passages 46 and 48, and the electromagnetic valves 50 and 52 of the second embodiment. Since the existing pump 22 that circulates between the two and only the four-way valve 60 is installed, the number of operation ends controlled by the ECU 54 is smaller than that in the first and second embodiments. The circuit configuration can be further simplified. Further, the controllability of the cycle 8 can be further improved by reducing the number of operation ends.

Although the description of one embodiment of the present invention has been completed above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, the circuit configuration in the third embodiment may be a configuration having the cooling water circuit 6 as in the first embodiment, and in this case, at least an operation end controlled by the ECU 54 compared to the first embodiment. The circuit number can be further reduced and the circuit configuration can be simplified.

  Moreover, in the said 3rd Embodiment, although the flow of the refrigerant | coolant which passes the exhaust gas heat exchanger 24, and the flow of exhaust gas become a parallel flow at the time of formation of the Rankine path | route 40 and become a countercurrent flow at the time of formation of the heat path | route 44, Rankine It is also possible to configure the circuit so that it becomes a counter flow when the path 40 is formed and a parallel flow when the heat path 44 is formed. In this case, the same effect as described above can be obtained.

It is a schematic diagram which shows the state in which the Rankine cycle path | route was formed in the waste heat utilization apparatus of the internal combustion engine which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the state in which the heat pipe path | route was formed in the waste heat utilization apparatus of FIG. It is a schematic diagram which shows the state in which the Rankine cycle path | route was formed in the waste heat utilization apparatus of the internal combustion engine which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the state in which the Rankine cycle path | route was formed in the waste heat utilization apparatus of the internal combustion engine which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the state in which the heat pipe path | route was formed in the waste heat utilization apparatus of FIG.

Explanation of symbols

2,56,58 Waste heat utilization device 4 Engine (Internal combustion engine)
6 Cooling water circuit 8 Rankine cycle circuit 12 Heat exchanger (second heat exchanger)
16 Bypass (second bypass)
20 Temperature sensor 22 Refrigerant pump (pump, first pump)
24 Exhaust gas heat exchanger (heat exchanger)
28 expander 30 condenser 34 second refrigerant pump (pump, second pump)
36 Bypass path 46 Bypass path (1st pump bypass path)
48 Bypass (second pump bypass)
38 energy generation circuit section 40 Rankine cycle path 42 heat exchange circuit section 44 heat pipe path 60 four-way valve 60a first communication path 60b second communication path 60c third communication path 60d fourth communication path

Claims (6)

A waste heat utilization apparatus for recovering waste heat of an internal combustion engine from a plurality of heat media, wherein the heat medium has a high temperature heat medium having waste heat at a predetermined temperature, and a low temperature having waste heat that is lower than the predetermined temperature. Comprising a heat medium and
A heat exchanger that exchanges heat with the high-temperature heat medium and heats the working fluid heat-exchanged with the low-temperature heat medium, an expander that expands the working fluid that passes through the heat exchanger and generates a driving force, and the expander A condenser that condenses the working fluid that passes through the pump and a pump that circulates the working fluid, and a heat exchange circuit unit is configured from the internal combustion engine and the heat exchanger, and an energy generation circuit unit is configured from the expander and the condenser And a Rankine cycle circuit that forms a Rankine cycle path by circulating a working fluid between the energy generation circuit unit and the heat exchange circuit unit by the pump,
The Rankine cycle circuit has a bypass path that bypasses the energy generation circuit section, and the circuit is switched to the bypass path to heat the low-temperature heat medium with the working fluid heated and evaporated by the heat exchanger. A heat pipe path is formed by circulating a working fluid through the heat exchange circuit section and the bypass path by a pump, and the circuit is switched to the bypass path in accordance with an operating state of the internal combustion engine, and the Rankine cycle path And a path switching means for switching between the heat pipe path and
The waste heat utilization apparatus for an internal combustion engine, wherein the pump is arranged to circulate a liquid working fluid regardless of the path switching by the path switching means. The pump is disposed between the energy generation circuit unit and the heat exchange circuit unit, and circulates a working fluid from the energy generation circuit unit toward the heat exchange circuit unit, and the low-temperature heat. A second pump that circulates the working fluid heat-exchanged with the medium toward the heat exchanger;
The Rankine cycle circuit further includes a first pump bypass path that bypasses the first pump and a second pump bypass path that bypasses the second pump,
The path switching means includes means for switching circuits to the first pump bypass path and the second pump bypass path, and means for controlling the operation of the first pump and the second pump, and forms the Rankine cycle path. Sometimes the first pump bypass path is closed to drive the first pump, while the second pump bypass path is opened to stop the second pump, and when the heat pipe path is formed, the first pump bypass path is 2. The internal combustion engine according to claim 1, wherein the first pump is stopped by opening one pump bypass passage, and the second pump is driven by closing the second pump bypass passage. Heat utilization device. The pump is disposed between the energy generation circuit unit and the heat exchange circuit unit,
The Rankine cycle circuit communicates the discharge port of the pump and the heat exchange circuit unit in conjunction with the first communication path that communicates the energy generation circuit unit and the suction port of the pump. A second communication path, a third communication path for communicating the heat exchange circuit section and the suction port of the pump, and a fourth communication for communicating the discharge port of the pump and the bypass path in conjunction with the third communication path. Including a four-way valve consisting of a passageway,
The path switching means includes means for controlling the switching of the four-way valve. When the Rankine cycle path is formed, the third communication path and the fourth communication path of the four-way valve are closed to close the first communication path and the second communication path. While communicating with the communication path, when the heat pipe path is formed, the first communication path and the second communication path of the four-way valve are closed to connect the third communication path and the fourth communication path. The waste heat utilization apparatus for an internal combustion engine according to claim 1. The low-temperature heat medium is cooling water that exchanges heat with the internal combustion engine, and a cooling water circuit in which the cooling water passing through the internal combustion engine circulates;
A second heat exchanger that is inserted in the cooling water circuit and exchanges heat between the cooling water and the working fluid before reaching the heat exchanger;
Further comprising a second bypass path that configures the cooling water circuit and bypasses the second heat exchanger;
The path switching means includes means for switching the circuit of the cooling water circuit to a second bypass path, and holds the circuit on the second heat exchanger side when the heat pipe path is formed. Or the waste heat utilization apparatus of the internal combustion engine of 3.   4. The internal combustion engine according to claim 2, wherein the low-temperature heat medium is the same fluid as the working fluid circulating in the Rankine cycle circuit, and the working fluid directly bears waste heat of the internal combustion engine. Waste heat utilization equipment. A temperature sensor for detecting the temperature of the working fluid;
The said path | route switching means contains a means to control the rotation speed of the said pump and the load of the said expander according to the temperature of the working fluid detected by the said temperature sensor. Waste heat utilization device for internal combustion engines.

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