JP2009191625A - Waste heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover waste heat, without impairing the cooling performance of an engine. <P>SOLUTION: A storage tank 15, a first pump 4 and a three-way valve 5 are arranged on the upstream side of the engine of a refrigerant passage 3 possessed by a waste heat recovery device 1. The three-way valve 3 branches off from the refrigerant passage 3, and forms a first relief circuit together with a first relief passage 20 for returning a refrigerant discharged from the first pump 4 to the storage tank 15. A second pump 6, a second three-way valve 7, an evaporator 8, a superheater 9, a power regenerating part 10 and a condenser 14 are arranged in order from the near side in an engine body 2a on the downstream side of the engine body 2a. An exhaust pipe 16 pulled out of the engine body 2a is connected in order of the superheater 9 and the evaporator 8. The second three-way valve 7 branches off from the refrigerant passage 3, and forms a second relief circuit together with a second relief passage 22 for returning the refrigerant discharged from the second pump 6 to the upstream side of the engine body 2a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a waste heat recovery apparatus that recovers waste heat in an engine.

  2. Description of the Related Art Conventionally, there is known a waste heat recovery device that recovers waste heat generated by driving an internal combustion engine (engine) using a Rankine cycle. In such a waste heat recovery device, for example, the water cooling cooling system of the engine has a sealed structure, and when the engine is cooled, the refrigerant that has evaporated by exchanging heat with the engine, that is, the waste heat in the engine is absorbed. Some of the evaporated refrigerant is further heated to a high temperature by exhaust exhausted from the engine. Such waste heat recovery means recovers the waste heat energy generated in the engine by driving the expander with the gas phase refrigerant heated to convert the energy of the gas phase refrigerant into electric energy or the like. Can do. The gas-phase refrigerant from which energy has been recovered is liquefied in the condenser. The refrigerant liquefied by the condenser is introduced into the engine, and again obtains waste heat and evaporates to contribute to the recovery of waste heat. For example, Patent Document 1 discloses an internal combustion engine that employs such a configuration to recover waste heat.

JP 2000-345835 A

  By the way, it is common to use a pump for the circulation of the refrigerant, including the configuration disclosed in Patent Document 1. The steam forming the Rankine cycle is more efficient as the pressure is higher. For this reason, if the discharge pressure of the pump is increased, the efficiency of the Rankine cycle can be improved. However, when the discharge pressure of the pump is increased, the discharge amount of the refrigerant increases, and there is a possibility that the waste heat recovery efficiency due to the Rankine cycle is reduced. For example, if the amount of liquid refrigerant supplied to the steam generator is too large compared to the amount of heat generated at that time, steam will not be generated, so the Rankine cycle cannot be established and waste heat recovery cannot be performed. is assumed. As described above, it is assumed that it is difficult to achieve both the required refrigerant pressure and the supply amount in the refrigerant supply by the pump.

  Accordingly, an object of the present invention is to perform efficient waste heat recovery without impairing the cooling performance of the engine.

  In order to solve such a problem, a waste heat recovery apparatus according to the present invention is driven by a refrigerant that circulates in a water jacket formed in an engine, a vapor generation unit that vaporizes the refrigerant, and vapor of the refrigerant. And a refrigerant supply amount control means for controlling a refrigerant supply amount to the steam generation section based on a detection result of the steam generation detection means. (Claim 1). By setting it as such a structure, when the state of a refrigerant | coolant is not in the state which can generate | occur | produce a vapor | steam, the refrigerant | coolant supply amount to a vapor | steam generation part is suppressed. On the other hand, waste heat can be efficiently recovered by supplying the refrigerant when steam can be generated in the steam generating section.

  In such a waste heat recovery apparatus, the refrigerant is discharged from the first pump based on the first pump for supplying the refrigerant into the engine, the engine temperature acquisition means, and the engine temperature acquired by the engine temperature acquisition means. And a first relief circuit for returning the refrigerant to the upstream side of the first pump (claim 2). Here, the engine temperature is, for example, the wall temperature of the cylinder block. This value is taken into account for adjusting the amount of cooling water introduced into a water jacket formed in the engine in order to properly cool the engine. Any value other than the wall temperature of the cylinder block can be adopted as long as the value can evaluate the thermal reliability of the engine. When there is a possibility of overcooling when more refrigerant is introduced into the water jacket from the state of the engine, the introduction of the cooling water into the water jacket is suppressed through the first relief circuit.

  Thus, when it is set as the structure which adjusts the quantity of the refrigerant | coolant introduce | transduced into an engine, it is convenient if the buffer area | region which stores the refrigerant | coolant which is not introduce | transduced in an engine exists. Therefore, a storage tank for storing the refrigerant is provided, and a first relief circuit is provided for returning the refrigerant discharged from the first pump to the upstream side of the first pump based on the engine temperature acquired by the engine temperature acquisition means. It is desirable to have a configuration (claim 3).

  In such a waste heat recovery apparatus, the steam generation unit is an evaporator that evaporates the refrigerant by heat of engine exhaust gas, and supplies the refrigerant to the evaporator between the engine and the evaporator. A second pump may be provided, and the refrigerant supply amount control means may be a second relief circuit that returns the refrigerant discharged from the second pump to the upstream side of the engine. The evaporator is provided separately from the main body of the engine. By adopting such a configuration, it is possible to avoid introducing the refrigerant into the evaporator in a situation where it is difficult to evaporate the refrigerant. If steam cannot be generated despite the introduction of the refrigerant into the evaporator, effective waste heat recovery cannot be performed. For example, when it is determined that it is difficult to generate steam effectively from the saturated vapor temperature of the refrigerant introduced into the evaporator and the temperature of the exhaust gas introduced into the evaporator, the refrigerant is passed through the second relief circuit. Relieve. After that, if the refrigerant is introduced into the evaporator when the conditions for vaporizing the refrigerant are satisfied, the waste heat can be efficiently recovered.

  In addition, even if it is the structure which only adjusts introduction | transduction of the refrigerant | coolant in an engine, the efficiency of waste heat recovery can be improved. That is, a refrigerant that circulates in a water jacket formed in the engine, a vapor generation unit that vaporizes the refrigerant, a power regeneration unit that is driven by the vapor of the refrigerant, and a first unit that supplies the refrigerant into the engine. 1 pump, engine temperature acquisition means, and a first relief circuit for returning the refrigerant discharged from the first pump to the upstream side of the first pump based on the engine temperature acquired by the engine temperature acquisition means, It can also be set as the waste heat recovery apparatus provided with (Claim 5).

  According to the waste heat recovery apparatus of the present invention, since the refrigerant discharged from the pump is relieved according to the state of the engine and the steam generation unit, the refrigerant is discharged even when the discharge pressure of the pump is improved. Excess supply can be avoided and efficient recovery of waste heat can be performed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an engine 2 in which the waste heat recovery apparatus 1 of the present embodiment is incorporated in an engine body 2a.

  A water jacket is formed in the engine body 2a, and a coolant that is cooling water circulates in the water jacket. The waste heat recovery apparatus 1 includes a refrigerant path 3 through which refrigerant flows. A storage tank 15 for storing the refrigerant is disposed upstream of the engine main body 2a in the refrigerant path 3, and the refrigerant in the storage tank 15 is supplied between the storage tank 15 and the engine main body 2a into the engine main body 2a. One pump 4 is arranged. A first three-way valve 5 is disposed between the first pump 4 and the engine body 2a.

  The first three-way valve 5 forms a first relief circuit in the present invention together with a first relief path 20 that branches from the refrigerant path 3 and returns the refrigerant discharged from the first pump 4 to the storage tank 15. A check valve 21 is attached to the first relief path 20. The first three-way valve 5 is electrically connected to an ECU (Electronic control unit) 26.

  In the refrigerant path 3 on the downstream side of the engine body 2a, in order from the side closer to the engine body 2a, the second pump 6, the second three-way valve 7, the evaporator 8 corresponding to the steam generating part in the present invention, the superheater 9, A power regeneration unit 10 and a condenser 14 are arranged. The above-described storage tank 15 is installed downstream of the condenser 14. Further, an exhaust pipe 16 through which the exhaust gas discharged from the exhaust port flows is drawn out from the engine body 2a, and the superheater 9 and the evaporator 8 are connected in this order.

  The second pump 6 sucks the refrigerant from the engine body 2 a and supplies it to the evaporator 8. In the evaporator 8, heat is obtained from the exhaust gas flowing through the exhaust pipe 16, and the refrigerant is vaporized. The second three-way valve 7 forms a second relief circuit in the present invention together with a second relief path 22 that branches from the refrigerant path 3 and returns the refrigerant discharged from the second pump 6 to the upstream side of the engine body 2a. . A check valve 23 is attached to the second relief path 20. The second three-way valve 7 is electrically connected to the ECU 26, and the second relief circuit constitutes the refrigerant supply amount control means in the present invention.

  The superheater 9 recovers heat from the exhaust gas in the exhaust pipe 16 and further imparts heat to the steam passing through the refrigerant passage 3, and improves the recovery efficiency of waste heat.

  The power regeneration unit 10 includes a turbine 11 and a generator 12 having a common shaft with the turbine 11. That is, the turbine 11 is driven by the vapor of the refrigerant flowing through the refrigerant path 3, and the waste heat of the engine is recovered by using the generator 12 as electric energy. The collected electricity is stored in a power storage device 13 connected to the generator 12.

  The engine body 2a is provided with a first temperature sensor 17 for measuring the wall temperature of the cylinder block. The evaporator 8 is provided with a pressure sensor 18 for measuring the pressure P1 of the refrigerant introduced. Further, a second temperature sensor 19 for measuring the temperature of the exhaust gas introduced into the evaporator 8 is installed upstream of the evaporator 8 in the exhaust pipe 16. The first temperature sensor 17, the pressure sensor 18, and the second temperature sensor 19 are electrically connected to the ECU 26, respectively. The first temperature sensor 17 corresponds to the engine temperature acquisition means in the present invention, and the pressure sensor 18 and the second temperature sensor 19 form part of the steam generation detection means in the present invention. That is, the saturation temperature T2X at the pressure P1 is calculated from the pressure P1 acquired by the pressure sensor 18. The calculated saturation temperature T2X and the temperature of the exhaust gas acquired by the second temperature sensor 19 are compared to determine whether or not the refrigerant can be vaporized in the evaporator 8. The calculation related to this determination is performed by the ECU 26.

  The operation and control of the waste heat recovery apparatus 1 configured as described above will be described with reference to the drawings. FIG. 2 is a flowchart illustrating an example of control performed by the ECU 26. First, in step S1, the ECU 26 confirms that the engine 2 is in a starting state, and proceeds to step S2. In step S2, T seconds are counted by a counter incorporated therein. This is a measure for performing the series of controls shown in FIG. 2 every T seconds. After counting T seconds, the ECU 26 performs the process of step S3. In step S3, it is determined whether or not the refrigerant in the storage tank 15 is introduced into the engine body 2a. Specifically, it is determined whether or not the wall temperature T1 of the cylinder block acquired by the first temperature sensor 17 is equal to or higher than a temperature T1X set in advance as a threshold value. This temperature T1X is set as a value with which it can be determined that no supercooling will occur even if a refrigerant is further introduced into the engine body 2a. When the wall temperature T1 is equal to or higher than the temperature T1X, the process proceeds to step S4. When the process proceeds to step S4, the refrigerant is not relieved in the first relief valve 5 as will be described in detail later, and the refrigerant discharged from the first pump 4 is supplied to the engine body 2a (steps S5 and S6). . The supplied refrigerant is heated in the engine body 2a. On the other hand, when the wall temperature T1 is lower than the temperature T1X, the process proceeds to step S7. When it progresses to step S4, the relief | relief of the refrigerant | coolant in the 1st relief valve 5 is performed so that it may explain in full detail later (step S8, step S9). Thereby, supply of the refrigerant discharged from the first pump 4 to the engine body 2a is avoided. As a result, the engine body 2a is not excessively cooled. That is, the amount of the refrigerant can be reduced within a range in which the thermal reliability of the engine main body 2a is ensured, and a state in which vaporization is easy can be created.

  If the ECU 26 determines YES in step S3, the ECU 26 proceeds to step S4. In step S4, it is determined whether or not the temperature T2 of the exhaust gas introduced into the evaporator 19 is equal to or higher than the saturation temperature T2X at the refrigerant pressure P1 introduced into the evaporator 8. The saturation temperature T2X is a value that varies depending on the state of the refrigerant pumped by the second pump 6. If YES is determined in this step S4, the process proceeds to step S5. In step S5, as shown in FIG. 3, neither the first relief valve 5 nor the second relief valve 7 is controlled to perform relief. Therefore, the liquid refrigerant in the storage tank 15 is introduced into the engine body 2a by the first pump 4, and the refrigerant whose temperature has been raised by the engine body 2a is sucked up by the second pump 6 and introduced into the evaporator 8. The refrigerant introduced into the evaporator 8 is vaporized by the heat of the exhaust gas. The vaporized refrigerant is sent to the superheater 9 to obtain further heat. The steam of the refrigerant whose quality is improved by obtaining heat in the superheater 9 drives the turbine 11. Thereby, the generator 12 operates and the waste heat of the engine is recovered as electric energy. The vaporous refrigerant after driving the turbine 11 is sent to the condenser 14. The refrigerant sent to the condenser 14 is returned to the liquid and flows into the storage tank 15 where it is stored.

  On the other hand, if NO is determined in step S4, the process proceeds to step S6. In step S6, as shown in FIG. 4, control is performed so that the first relief valve 5 is not relieved and the second relief valve 7 is relieved. Accordingly, the refrigerant introduced into the engine body 2a by the first pump 4 is sucked up by the second pump 6 and then returned to the upstream side of the engine body 2a through the second relief path 22 as indicated by an arrow 25 in the drawing. It is. The refrigerant returned to the engine body 2 a is heated again in the engine body 2 a and sucked up by the second pump 6.

  If the ECU 26 determines NO in step S3, the ECU 26 proceeds to step S7. In step S7, it is determined whether or not the temperature T2 of the exhaust gas introduced into the evaporator 8 is equal to or higher than the saturation temperature T2X at the pressure P1 of the refrigerant introduced into the evaporator 8. That is, the same determination as in step S4 is performed. If YES is determined in this step S7, the process proceeds to step S8. In step S8, as shown in FIG. 5, the first relief valve 5 is relieved and the second relief valve 7 is not relieved. Therefore, the refrigerant sucked from the storage tank 15 by the first pump 4 is returned to the storage tank 15 through the first relief path 20 as indicated by an arrow 24 in the drawing. Thereby, excessive cooling of the engine main body 2a is avoided. On the other hand, the refrigerant already introduced into the engine body 2 a is sucked up by the second pump 6 and introduced into the evaporator 8. The refrigerant introduced into the evaporator 8 is vaporized by the heat of the exhaust gas. The vaporized refrigerant is sent to the superheater 9 and the turbine 11 to be used for waste heat recovery.

  On the other hand, if NO is determined in step S7, the process proceeds to step S9. In step S9, as shown in FIG. 6, control is performed so that the first relief valve 5 is not relieved and the second relief valve 7 is relieved. Accordingly, no new refrigerant is introduced into the engine body 2a, and no refrigerant is supplied to the evaporator 8. Such a state is, for example, a state immediately after the cold start. When the first relief valve 5 is in the relief state, the heat capacity is not increased because no external refrigerant is introduced into the engine body 2a. Moreover, there is no outflow of the refrigerant to the outside. For these reasons, waste of heat in the engine body 2a can be suppressed. Moreover, it leads also to completion of the early warming-up of the engine main body 2a. Further, when the second relief valve 7 is in the relief state, introduction of the refrigerant into the evaporator 8 that is not in a state where steam can be generated is avoided. Thereby, efficient waste heat recovery can be performed.

  After the processes in steps S5 to S9 described above, all return. Then, again, counting for T seconds is performed in step S2. That is, the control of the waste heat recovery apparatus 1 is repeatedly performed at intervals of T seconds. As a result, the state of each part converges to an appropriate range from the viewpoint of cooling the engine body 2a and recovering waste heat.

  As described above, in the waste heat recovery apparatus of the present invention, the introduction of the refrigerant is controlled according to the state of the refrigerant introduction destination. Thus, efficient engine cooling and waste heat recovery can be performed. At this time, it is difficult to achieve both the pressure of the supplied refrigerant and the supply amount only by controlling the drive of the pump. However, according to the present invention, excess refrigerant is relieved, so the pressure of the refrigerant It is possible to achieve both an improvement in the amount of refrigerant and an appropriate refrigerant supply amount.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to them. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, each of the first relief valve 5 and the second relief valve 7 is configured to completely switch between a state in which the refrigerant is relieved and a state in which the refrigerant is not relieved, but these can be replaced with a relief valve whose opening degree can be adjusted. By using a relief valve whose opening degree can be adjusted, more precise control can be performed. Furthermore, a configuration as shown in FIG. The waste heat recovery apparatus 50 shown in FIG. 7 has a configuration in which the storage tank 15 is removed from the waste heat recovery apparatus 1 shown in FIG. Furthermore, the 1st relief valve 51 is set as the structure which can adjust an opening degree. By adopting such a configuration and adjusting the opening degree, the wall temperature T1 is controlled, and P1 is controlled. Thereby, engine cooling and efficient waste heat recovery can be performed.

It is explanatory drawing which showed schematic structure of the engine which incorporated the waste heat recovery apparatus in the engine main body. It is a flowchart which shows an example of control of a waste heat recovery apparatus. It is explanatory drawing which showed the engine which made the state which does not relieve the 1st relief valve of a waste heat recovery apparatus, and a 2nd relief valve. It is explanatory drawing which showed the engine which made the state which does not relieve the 1st relief valve of a waste-heat-recovery apparatus, and the state which made the 2nd relief valve relief. It is explanatory drawing which showed the engine which made the state which reliefd the 1st relief valve of the waste heat recovery apparatus, and did not relieve the 2nd relief valve. It is explanatory drawing which showed the engine which made the state which reliefs the 1st relief valve and 2nd relief valve of a waste heat recovery apparatus. It is explanatory drawing which showed the engine incorporating the waste heat recovery apparatus of another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waste heat recovery apparatus 2 Engine 2a Engine main body 3 Refrigerant path 4 1st pump 5 1st relief valve 6 2nd pump 7 2nd relief valve 8 Evaporator 9 Superheater 10 Power regeneration part 11 Turbine 12 Generator 13 Power storage device 14 Condenser 15 Storage tank 16 Exhaust pipe 17 First temperature sensor 18 Pressure sensor 19 Second temperature sensor 20 First relief path 22 Second relief path 26 ECU

Claims (5)

Refrigerant circulating in a water jacket formed in the engine;
A steam generating section where the refrigerant is vaporized;
A power regeneration unit driven by the refrigerant vapor;
Steam generation detection means;
Based on the detection result of the steam generation detection means, a refrigerant supply amount control means for controlling the refrigerant supply amount to the steam generation section;
A waste heat recovery device comprising: The waste heat recovery apparatus according to claim 1,
A first pump for supplying the refrigerant into the engine;
Engine temperature acquisition means;
A first relief circuit for returning the refrigerant discharged from the first pump to the upstream side of the first pump based on the engine temperature acquired by the engine temperature acquisition means;
A waste heat recovery device comprising: The waste heat recovery apparatus according to claim 1,
A storage tank for storing the refrigerant;
A first pump for supplying the refrigerant in the storage tank into the engine;
Engine temperature acquisition means;
A first relief circuit for returning the refrigerant discharged from the first pump to the upstream side of the first pump based on the engine temperature acquired by the engine temperature acquisition means;
A waste heat recovery device comprising: The waste heat recovery apparatus according to claim 1,
The steam generation unit is an evaporator that evaporates the refrigerant by heat of engine exhaust gas,
A second pump for supplying a refrigerant to the evaporator between the engine and the evaporator;
The waste heat recovery apparatus, wherein the refrigerant supply amount control means is a second relief circuit that returns the refrigerant discharged from the second pump to the upstream side of the engine. Refrigerant circulating in a water jacket formed in the engine;
A steam generating section where the refrigerant is vaporized;
A power regeneration unit driven by the refrigerant vapor;
A first pump for supplying the refrigerant into the engine;
Engine temperature acquisition means;
A first relief circuit for returning the refrigerant discharged from the first pump to the upstream side of the first pump based on the engine temperature acquired by the engine temperature acquisition means;
A waste heat recovery device comprising:

Images