JP2005113810A - Stirling agency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stirling engine, using exhaust gas of an internal combustion engine for a high-temperature heat source, in which exhaust gas energy of the internal combustion engine to be supplied to the stirling engine is limited to be prescribed quantity or less. <P>SOLUTION: This stirling engine 10 uses exhaust gas of the internal combustion engine 1 for a high-temperature heat source. An exhaust gas passage 2 in the internal combustion engine 1 comprises a main exhaust gas passage 4 connected to a heater of the stirling engine 10, and a bypass exhaust gas passage 5 to bypass the heater of the stirling engine 10. At an upstream side branch part of the main exhaust gas passage 4 to the bypass exhaust gas passage 5, an exhaust gas distribution means 8 is provided to respectively distribute exhaust gas by a required quantity to the main exhaust gas passage and the bypass exhaust gas passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a Stirling engine having a function of protecting the operation of a Stirling engine that uses exhaust gas from an internal combustion engine as a high heat source.

  In a general Stirling engine as shown in Patent Document 1, since the combustion gas obtained by burning fuel in the combustor is used as a high heat source, the amount of heat generated in the combustor can be self-controlled, and the input of the Stirling engine As a result, the output control of the Stirling engine was easy.

  In addition, as shown in Patent Document 2, a Stirling engine that does not include a combustor uses a relatively stable heating element such as solar heat, geothermal heat, and factory waste heat as a high-temperature source. The need to control the amount of heat input was low.

  Furthermore, in order to recover the energy of the exhaust gas discharged from the internal combustion engine to obtain auxiliary machine driving power for the automobile, the exhaust gas of the internal combustion engine is used as a high heat source of the Stirling engine and the cooling water of the internal combustion engine is Stirling. There has been a Stirling engine (Patent Document 3) in which a rotor of a generator is connected to a rotating shaft of a Stirling engine as a low heat source of the engine.

  In the Stirling engine for auxiliary drive power generation as shown in Patent Document 3, the output range of the internal combustion engine for automobiles is extremely wide from about 4 horsepower to about 200 horsepower, and the waste heat energy that the exhaust gas has corresponds to it. And fluctuate widely.

  However, the frequency of operation of an internal combustion engine at high output is rare, and at the maximum output of the internal combustion engine, if the Stirling engine is constructed so that it will not be damaged even by its large waste heat energy, the moving parts will be robust. In addition, the Stirling engine case becomes thicker to withstand high-temperature and high-pressure working gas, resulting in an increase in weight and cost, resulting in increased friction loss and reduced efficiency during rated operation.

JP 2002-221888 A Japanese Patent Laid-Open No. 2003-13805 JP 2002-266701 A

  The problem to be solved by the present invention is to provide a small, lightweight and inexpensive Stirling engine that can be operated normally without being affected by a large increase in output of the internal combustion engine.

  In the first aspect of the invention, the exhaust gas passage for guiding the exhaust gas of the internal combustion engine is branched into a main exhaust gas passage that communicates with the heat exchanger of the Stirling engine and a bypass exhaust gas passage that bypasses the main exhaust gas passage, The Stirling engine is characterized in that an exhaust gas flow control valve having a protection function for the Stirling engine is disposed at an upstream branch portion between the main exhaust gas passage and the bypass exhaust gas passage.

  A second aspect of the present invention is the Stirling engine according to the first aspect, wherein the exhaust gas flow rate control valve is controlled based on operating states of the internal combustion engine and the Stirling engine.

  According to the first aspect of the present invention, an exhaust gas flow rate control valve having a protection function when the output of the internal combustion engine is greatly increased compared to the normal operation output and the exhaust gas energy of the internal combustion engine is remarkably increased. With this operation, the flow rate of the bypass exhaust gas flowing through the bypass exhaust gas passage in the exhaust gas flow rate of the internal combustion engine increases, and the flow rate of the main exhaust gas flowing through the main exhaust gas passage leading to the Stirling engine correspondingly decreases. Therefore, the Stirling engine due to the large exhaust gas energy generated from the internal combustion engine does not need to withstand a high load, and as a result, the transmission mechanism around the rotation shaft of the Stirling engine and the load resistance of the piston of the Stirling engine are reduced. This makes it possible to reduce the weight, size and cost of the Stirling engine.

Further, since the moving parts around the rotation axis of the Stirling engine are reduced, the power transmission loss of the power transmission mechanism is reduced, and the power generation efficiency of the Stirling engine is improved.

  Furthermore, the parts around the rotating shaft of the Stirling engine are reduced in size, so that the crankcase of the Stirling engine becomes smaller, and the pressure resistance of this crank chamber is maintained even if the wall of the crank chamber wall of the Stirling engine is thinned. This makes it possible to reduce the size, weight and cost of the Stirling engine.

  Furthermore, since the working gas temperature and pressure of the Stirling engine can be reduced by reducing the load on the Stirling engine, the pressure resistance of the heat exchanger of the Stirling engine and the heat resistance and pressure resistance of the Stirling engine structural material are reduced. This makes it possible to lower the standard, and to reduce the size and weight by reducing the thickness, and to reduce the cost by selecting an inexpensive material.

  In addition, since the Stirling engine does not require high output, the required torque of the generator that controls the rotational speed of the Stirling engine is reduced, and the generator can be reduced in size, weight, and cost.

  According to the second aspect of the present invention, since the exhaust gas flow rate control valve is controlled based on the operating state of the internal combustion engine and the Stirling engine, the Stirling engine can be operated with the highest efficiency while considering the durability. Can drive.

  Hereinafter, an embodiment of the present invention illustrated in FIGS. 1 and 2 will be described.

  The power device to which the present invention is applied includes a water-cooled multi-cylinder internal combustion engine 1, a Stirling engine 2 driven by exhaust gas from the internal combustion engine 1, and an electric motor having a rotor directly connected to a crankshaft 23 of the Stirling engine 2. And a motor generator 3 having the function of a generator, a battery 4 for charging the electric power generated by the motor generator 3, and discharging the motor generator 3 with the charged electric power, The power unit is mounted on a vehicle, and the internal combustion engine 1 drives the vehicle. The motor generator 3 is a load device that is driven by the Stirling engine 2 and is also a drive device that drives the Stirling engine 2 by receiving power supplied from the battery 4.

  In the internal combustion engine 1, a crankshaft that is rotationally driven by a piston that is reciprocally fitted to a plurality of cylinders and transmits power to a drive wheel of the vehicle via a power transmission device, and a fuel such as a fuel injection valve An intake device that guides intake air that is mixed with fuel supplied from the supply device to form an air-fuel mixture to the combustion chamber, and guides the combustion gas generated by the combustion of the fuel in the combustion chamber to the outside of the internal combustion engine 1 as exhaust gas. And an exhaust device having an exhaust pipe 6.

  The exhaust pipe 6 is provided with an exhaust purification device 7 containing a catalyst for purifying exhaust gas. The exhaust pipe 6 on the downstream side of the exhaust pipe 6 is connected to a main exhaust gas pipe 8 constituting a main exhaust gas passage. The exhaust gas is branched into a bypass exhaust gas pipe 9 that constitutes a bypass passage that bypasses the main exhaust gas passage, and an exhaust gas that controls the flow rate of the main exhaust gas flowing through the main exhaust gas pipe 8 is provided at the upstream branch portion. A flow rate control valve 10 is provided. The exhaust gas flow rate control valve 10 has a downstream end of a valve body 10a of the exhaust gas flow rate control valve 10 pivoted to a branch portion, and an upstream end of the valve body 10a is a main exhaust gas. The flow rate of the exhaust gas that swings toward the pipe 8 or the bypass exhaust gas pipe 9 and flows through the main exhaust gas pipe 8 and the bypass exhaust gas pipe 9 is adjusted, and the upstream end of the valve body 10a is the main exhaust gas. Main exhaust gas when in contact with the inner wall surface of the pipe 8 8 is fully closed and the bypass exhaust gas pipe 9 is fully opened, or when the upstream end of the valve body 10a contacts the inner wall surface of the bypass exhaust gas pipe 9, the bypass exhaust gas pipe 9 is fully closed and the main exhaust The gas pipe 8 is fully opened.

  Further, the downstream ends of the main exhaust gas pipe 8 and the bypass exhaust gas pipe 9 are aligned with each other so that the exhaust gas flowing in the main exhaust gas pipe 8 and the bypass exhaust gas pipe 9 merges into the downstream exhaust pipe 11. A silencer 12 is connected to the downstream exhaust pipe 11, and the exhaust gas flowing through the exhaust pipe 6 is divided into the main exhaust gas pipe 8 and the bypass exhaust gas pipe 9, and then again downstream. They are merged in the side exhaust pipe 11 and released into the atmosphere via the silencer 12.

  A Stirling engine 2 that uses exhaust gas discharged from the internal combustion engine 1 as a high heat source is rotatable in a cylinder 20, a crankcase 21 integrated with the cylinder 20, and a crank chamber 22 formed by the crankcase 21. The displacer piston 24 and the power piston 25 which are coaxially disposed in the cylinder 20 and are reciprocably fitted to each other, and the displacer piston 24 advances about 90 ° relative to the power piston 25. Due to the phase difference relationship, a connecting mechanism 26 such as a well-known crosshead mechanism, Lombic mechanism, or Scotch yoke mechanism that connects the displacer piston 24 and the power piston 25 to the crankshaft 23, a heater 27, a regenerator 28, The heat exchanger is configured by the heater 27, the regenerator 28, and the cooler 29.

  In the cylinder 20 of the Stirling engine 2, a high-temperature space 30, which is a variable volume space formed between the cylinder 20 and the displacer piston 24, and a variable volume space formed between the displacer piston 24 and the power piston 25. A certain low temperature space 31 is always in a communication state via flow paths formed in the heater 27, the regenerator 28, and the cooler 29, respectively, and the high temperature space 30, the low temperature space 31 and the flow path include a working gas. The high pressure helium gas of about 100 atm is sealed, and the heater 27 and the high temperature space 30 are communicated with each other via the communication path 32, and the cooler 29 and the low temperature space 31 are connected to the communication path 33. Are in communication with each other.

  The high-temperature heat source of the Stirling engine 2 is exhaust gas flowing from the internal combustion engine 1 through the exhaust pipe 6 through the main exhaust gas pipe 8, and this exhaust gas is combined with the working gas in the Stirling engine 2 in the heater 27. Heat exchange is performed, and the working gas in the high-temperature space 30 is heated.

  Further, the low-temperature heat source of the Stirling engine 2 is cooling water that cools the heat generating portion of the internal combustion engine 1, and this cooling water is supplied to the cooler 29 in the Stirling engine 2 via a cooling circuit (not shown). In 29, heat exchange is performed with the working gas in the low temperature space 31 of the Stirling engine 2, and the working gas in the low temperature space 31 is cooled.

  The motor generator 3 is provided with a field regulator 13 as load control means for controlling the load Ls of the Stirling engine 2 when the motor generator 3 functions as a generator. The field current is adjusted by 13 to control the load when the motor generator 3 generates power, that is, the load Ls of the Stirling engine 2.

  In addition, the battery 4 charged by the electric power generated by the motor generator 3 can supply power to the internal combustion engine 1 and all the electrical components of the vehicle, and the battery controller 14 including a voltage regulator, an inverter, etc. Thus, the charging of the battery 4 by the electric power generated by the motor generator 3 and the power supply from the battery 4 to the motor generator 3 and the electrical components are controlled.

  Next, operation control of the Stirling engine 2 by the ECU 5 will be described.

  In FIG. 1, the operation control system for the Stirling engine 2 includes, in addition to the ECU 5, a Stirling engine rotation speed detection means 15 that detects the Stirling engine rotation speed Ns of the Stirling engine 2 based on the rotation of the crankshaft 23, and field adjustment. Load detecting means 16 for detecting the load Ls of the Stirling engine 2 by detecting the field current of the heater 13 and the exhaust gas before flowing into the heater 27 of the Stirling engine 2 through the main exhaust gas pipe 8 Exhaust gas temperature detection means 17 for detecting the temperature and high temperature gas space temperature detection means 18 for detecting the working gas temperature in the high temperature space 30 are provided.

  Hereinafter, the rotational speed control routine of the Stirling engine based on the control of the bypass exhaust gas passage flow rate executed by the ECU 5 during the operation of the internal combustion engine will be described with reference to the flowchart of FIG.

  In step S1, whether or not the internal combustion engine 1 in the stopped state is started and the internal combustion engine 1 is in operation or within a predetermined time (for example, 90 seconds) after the internal combustion engine is stopped is determined, for example. This routine is terminated when it is determined based on the engine speed or a timer and is not within a predetermined time during operation or after the internal combustion engine is stopped.

  If the determination in step S1 is affirmative, in step S2, after the exhaust gas temperature T detected by the exhaust gas temperature detection means 17 is read, the process proceeds to step S3, where the exhaust gas temperature T is equal to or lower than the predetermined temperature Tc. It is determined whether or not. The predetermined temperature Tc is a temperature for distinguishing whether or not the Stirling engine 2 can be normally operated, and is set to a high temperature gas space temperature that does not cause the Stirling engine 2 to be broken or broken.

If the determination in step S3 is affirmative and it is determined that the exhaust gas temperature T is equal to or lower than the predetermined temperature Tc and the Stirling engine 2 can be operated normally, the Stirling engine rotation speed detecting means 15 detects the exhaust gas temperature in step S4. The rotational speed Ns of the Stirling engine 2 is read. Then, the process proceeds to step S5, where it is determined whether or not the Stirling engine rotational speed Ns is equal to or less than the maximum rotational speed Nsmax. When the determination is affirmative, the process proceeds to step S6, where the high temperature gas space temperature detecting means 18 performs. after hot gas space temperature T _H of the detected high temperature space 30 is read, the process proceeds to step S7, the hot gas space temperature T _H is determined whether it is less than the maximum hot gas space temperature Ts, the determination If YES, the process proceeds to step S8, and the valve body 10a swings to the bypass exhaust gas pipe 9 by the operation of the exhaust gas flow control valve 10, so that the bypass flow rate to the bypass exhaust gas pipe 9 decreases and the main exhaust gas is reduced. The Stirling engine rotation speed Ns increases until the Stirling engine rotation speed Ns becomes equal to the maximum rotation speed Nsmax, and the exhaust gas flow rate to the gas pipe 8 is controlled to increase. The output of the Turing engine 2 increases.

Further, in step S7, the hot gas space temperature T _H is determined whether it is less than the maximum hot gas space temperature Ts, the determination is negative, the hot gas space temperature T _H is the maximum hot gas space of the high-temperature space 30 When the temperature Ts is exceeded, the process goes to step S9, where the Stirling engine 2 is reduced so that the generator load L _S is reduced by a predetermined amount ΔL _{2 by} reducing the amount of field current supplied to the field regulator 13. Be controlled. As a result, a decrease in the load L _S, the engine rotational speed Ns increases.

Further, when the determination in step S5 is negative and the Stirling engine rotational speed Ns exceeds the maximum rotational speed Nsmax, the process proceeds to step S10, where the amount of field current supplied to the field regulator 13 is increased, thereby generating power. The Stirling engine 2 is controlled so that the mechanical load L _S increases by a predetermined amount ΔL ₁ . After a lapse of step S10, the process proceeds to step 11, generator load L _S is read in, the process proceeds to step S12, the generator load L _S is determined whether or less load limit L _M of the generator, its when the determination is affirmative, the process proceeds to step S13, after the hot gas space temperature T _H of the hot space 30 is read, the process proceeds to step S14, the hot gas space temperature T _H is less than or equal to the maximum hot gas space temperature Ts When it is determined whether or not there is an affirmative determination, the process returns to step S2.

Furthermore, in step S12, the generator load L _S is determined whether or less load limit L _M of the generator is negative, the process proceeds to step S15, the valve body 10a of the exhaust gas flow rate control valve 10 The exhaust gas flow rate control valve 10 operates so as to swing toward the main exhaust gas pipe 8 side, and the bypass exhaust gas passage flow rate is increased, and the exhaust gas flow rate to the main exhaust gas pipe 8 is controlled to decrease. . As a result, the decrease in the exhaust gas flow rate to the main exhaust gas pipe 8 accompanying the increase in the bypass flow rate decreases the Stirling engine rotational speed Ns, and the output of the Stirling engine 2 decreases.

Further, in step S14, the hot gas space temperature T _H is determined whether it is less than the maximum hot gas space temperature Ts, the the determination is negative, the process proceeds to step S15, the valve element of the exhaust gas flow rate control valve 10 The exhaust gas flow rate control valve 10 is operated so that 10a swings toward the main exhaust gas pipe 8 side, and the bypass exhaust gas passage flow rate is increased, and the exhaust gas flow rate to the main exhaust gas pipe 8 is decreased. Is done. As a result, the generator load L _S decreases due to the decrease in the exhaust gas flow rate to the main exhaust gas pipe 8 accompanying the increase in the bypass flow rate, and the output of the Stirling engine 2 decreases.

  Further, if it is determined in step S3 that the exhaust gas temperature T has exceeded the predetermined temperature Tc, the process proceeds to step S15, and the valve body 10a of the exhaust gas flow rate control valve 10 swings toward the main exhaust gas pipe 8 side. Thus, the exhaust gas flow rate control valve 10 operates, and the output of the Stirling engine 2 decreases due to the decrease in the exhaust gas flow rate to the main exhaust gas pipe 8 as the bypass flow rate increases.

  The embodiment shown in FIGS. 1 and 2 is configured as described above. Therefore, when the output of the internal combustion engine 1 is low, the bypass exhaust gas pipe 9 is fully closed, and the inside of the bypass exhaust gas pipe 9 is The bypass exhaust gas flow rate becomes zero, or the bypass exhaust gas flow rate flowing through the bypass exhaust gas pipe 9 by the exhaust gas flow rate control valve 10 is small.

  When the output of the internal combustion engine 1 increases, the exhaust gas distribution amount to the bypass exhaust gas pipe 9 is increased, thereby reducing the exhaust gas distribution amount to the main exhaust gas pipe 8 and entering the Stirling engine 2. The amount of heat can be limited within the required range.

  When the rotational speed Ns of the Stirling engine 2 increases and exceeds the maximum rotational speed Nsmax, the field current is increased by the field regulator 13 and the load of the motor generator 3, that is, the load of the Stirling engine 2 is increased. Ls increases, the bypass exhaust gas flow rate increases, the main exhaust gas flow rate decreases correspondingly, and the output of the Stirling engine 2 decreases.

Further, the rotation speed Ns of the Stirling engine 2 does not exceed the maximum rotational speed Nsmax, if hot gas space temperature T _H of the hot space 30 exceeds the maximum hot gas space temperature Ts is the field regulator 13 field current is reduced load of the electric generator 3, i.e. the load Ls Stirling engine 2 is reduced, the rotational speed of the Stirling engine 2 is increased, and decreased hot gas space temperature T _H of the hot space 30 The Stirling engine 2 is protected.

Furthermore, when the rotational speed Ns of the Stirling engine 2 exceeds the maximum rotational speed Nsmax, and hot gas space temperature T _H of the hot space 30 exceeds the maximum hot gas space temperature Ts is exhaust gas flow rate control valve 10 The exhaust gas flow rate control valve 10 is operated so that the valve body 10a swings toward the main exhaust gas pipe 8 side, and the exhaust gas flow rate to the main exhaust gas pipe 8 is controlled to be reduced. Protected.

  Thus, in the above-described embodiment, when the output of the internal combustion engine 1 is greatly increased compared to the normal operation output and the exhaust gas temperature of the internal combustion engine 1 is significantly increased, the exhaust gas flow control valve 10 In operation, among the exhaust gas flow rates of the internal combustion engine 1, the flow rate of the bypass exhaust gas flowing through the bypass exhaust gas tube 9 increases, and the flow rate of the main exhaust gas flowing through the main exhaust gas tube 8 leading to the Stirling engine 2 correspondingly. As a result, it is not necessary to endure the high load of the Stirling engine 2 due to the large exhaust gas energy generated from the internal combustion engine 1, and as a result, the coupling mechanism 26 around the crankshaft 23 of the Stirling engine 2 and the displacer piston 24 of the Stirling engine 2 By reducing the load resistance of the power piston 25, the Stirling engine 2 can be reduced in weight, size, and cost.

The rotation speed Ns is not more than the maximum rotational speed Nsmax Stirling engine 2, and when the hot gas space temperature T _H of the hot space 30 is equal to or less than the maximum hot gas space temperature Ts, the exhaust gas flow into the bypass exhaust gas pipe 9 Decreases, that is, the exhaust gas flow rate to the main exhaust gas pipe 8 increases, and the energy of the exhaust gas is effectively recovered by the Stirling engine 2.

Further, since the moving parts around the crankshaft 23 of the Stirling engine 2 are reduced, the power transmission loss of the coupling mechanism 26 is reduced, and the power generation efficiency of the Stirling engine is improved.

  Further, the parts around the crankshaft 23 of the Stirling engine 2 are reduced in size, so that the crankcase 21 of the Stirling engine 2 becomes smaller. Even if the crankcase 21 of the Stirling engine 2 is thinned, the pressure resistance of the crank chamber 22 is reduced. Thus, the Stirling engine 2 in this aspect can be reduced in size, weight, and cost.

  Furthermore, since the working gas temperature and pressure of the Stirling engine 2 can be reduced by reducing the load on the Stirling engine 2, the heater 27, the regenerator 28, and the cooler 29 that are heat exchangers of the Stirling engine 2. Pressure resistance, and the standard of heat resistance and pressure resistance of Stirling engine structural materials can be reduced, making it possible to reduce the size and weight by reducing the thickness, and to reduce costs by selecting inexpensive materials. .

  In addition, since the Stirling engine 2 does not require high output, the required torque of the motor generator 3 that controls the rotational speed of the Stirling engine 2 is reduced, and the motor generator 3 can be reduced in size, weight, and cost. Become.

  In the above embodiment, the calorific value of the exhaust gas of the internal combustion engine 1 flowing in the main exhaust gas pipe 8 is measured by measuring the exhaust gas temperature of the internal combustion engine 1 flowing in the main exhaust gas pipe 8. By measuring the exhaust gas calorific value of the internal combustion engine 1 flowing in the pipe 8 together, the exhaust gas calorific value can be detected more accurately.

It is explanatory drawing of the best form of this invention Stirling engine. 2 is a flowchart for explaining a control routine during operation of the Stirling engine shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Stirling engine, 3 ... Motor generator, 4 ... Battery, 5 ... ECU, 6 ... Exhaust pipe, 7 ... Exhaust gas purification device, 8 ... Main exhaust gas pipe, 9 ... Bypass exhaust gas pipe, 10 Exhaust gas flow control valve, 11 ... downstream exhaust pipe, 12 ... silencer, 13 ... field regulator, 14 ... battery controller, 15 ... Stirling engine rotational speed detection means, 16 ... load detection means, 17 ... exhaust Gas temperature detection means, 18 ... high temperature gas space temperature detection means,
20 ... Cylinder, 21 ... Crankcase, 22 ... Crank chamber, 23 ... Crankshaft, 24 ... Displacer piston, 25 ... Power piston, 26 ... Connecting mechanism, 27 ... Heater, 28 ... Regenerator, 29 ... Cooler, 30 ... high temperature space, 31 ... low temperature space, 32 ... communication path, 33 ... communication path.

Claims (2)

An exhaust gas passage that guides the exhaust gas of the internal combustion engine is branched into a main exhaust gas passage that leads to the heat exchanger of the Stirling engine and a bypass exhaust gas passage that bypasses the main exhaust gas passage,
A Stirling engine characterized in that an exhaust gas flow rate control valve having a protection function for the Stirling engine is disposed at an upstream branch portion between the main exhaust gas passage and the bypass exhaust gas passage.   The Stirling engine according to claim 1, wherein the exhaust gas flow control valve is controlled based on operating states of the internal combustion engine and the Stirling engine.

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