JP2006170022A - Waste heat recovery device and method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a thermoacoustic engine has poor startability in a conventional vehicle equipped with the thermoacoustic engine for recovering waste heat of an internal combustion engine. <P>SOLUTION: A waste heat recovery device for the internal combustion engine according to the invention has the thermoacoustic engine 11 comprising a heat accumulator 13 incorporated in a gas column pipe 12 filled with working fluid, a heat transfer member 14 for recovering the waste heat of exhaust gas from the internal combustion engine 10 and for heating the working fluid on an one end surface side of the heat accumulator 13 and a low-temperature side heat exchanger 15 for cooling the working fluid on the other end surface side of the heat accumulator 13. The waste heat recovery device is equipped with a branch pipe 34 branching from the middle of an exhaust pipe 24 and passing through the gas column pipe 12 and the heat transfer member 14 at the one end surface side to the heat accumulator 13, a shutter 35 for introducing a part of the exhaust gas into the branch pipe 34 and for heating the working fluid on the one end surface side of the heat accumulator 13 through the branch pipe 34, an operation judgment means for judging whether or not thermoacoustic self-excited vibration of the working fluid is started and a control means 26 for controlling operation of a switching means based on the judgment result of the judgment means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust heat recovery device for an internal combustion engine including a thermoacoustic engine that generates thermoacoustic self-excited vibration of a working fluid inside an air column tube, and an exhaust heat recovery method for the internal combustion engine.

  A thermoacoustic engine incorporates a heat storage section through which a working fluid can pass into an air column tube filled with a working fluid such as helium or argon, and forms a temperature gradient between both end faces of the heat storage section to produce a thermoacoustic sensor for the working fluid. Exciting vibration is generated, and it has a great feature that it does not have a mechanical movable part. Applications to generators and refrigerators are in progress.

  A thermoacoustic generator that generates power using a traveling wave generated by thermoacoustic self-excited vibration in this thermoacoustic engine is proposed in Patent Document 1. This thermoacoustic generator generates power in response to traveling waves generated by thermoacoustic self-excited vibration, in addition to a heat accumulator through which a working fluid can pass and a heating unit and a heat radiating unit arranged so as to sandwich the accumulator. And a frequency regulator that generates pressure vibration of the working fluid at an arbitrary frequency are connected to the air column tube so that efficient power generation can be performed. This frequency adjuster includes a linear motor and a piston cylinder. By reciprocating the piston cylinder, a mechanical pressure vibration is applied to the working fluid in the air column tube to obtain a thermoacoustic self-excited vibration having a desired frequency. It becomes possible.

  On the other hand, Patent Document 2 discloses a technique for recovering exhaust heat of exhaust gas discharged from an internal combustion engine using a thermoacoustic engine. This exhaust heat energy recovery device includes a resonance tube connected to an exhaust gas purification catalytic converter of an internal combustion engine, a heat accumulator provided on the base end side of the resonance tube, and a high temperature side heat arranged so as to sandwich the heat accumulator. It includes a sound wave generator including an exchanger and a low-temperature side heat exchanger, and a transducer that is provided at the end of the resonance tube and converts sound waves into mechanical vibrations and then converts them into electrical energy.

Japanese Patent Laid-Open No. 2003-324932 JP 2002-122020 A

  In a vehicle as disclosed in Patent Document 2 equipped with a thermoacoustic engine for recovering exhaust heat of exhaust gas exhausted from an internal combustion engine, the working fluid interposed on one end face side of the heat accumulator is heated. As a high-temperature side heat exchanger, a heat transfer member with poor thermal conductivity such as stainless steel considering the corrosion resistance and heat resistance against exhaust gas is straddled between the exhaust pipe and the resonance pipe on one end side of the regenerator. It is necessary to distribute.

  In the thermoacoustic engine, the operation start temperature at which the thermoacoustic self-excited vibration of the working fluid starts stably is higher than the operation stop temperature at which the thermoacoustic self-excited vibration of the working fluid does not occur, and a hysteresis phenomenon is observed. For example, when the thermoacoustic engine becomes the operating start temperature or higher and shifts to the operating state, the thermoacoustic engine continues to operate until the operating stop temperature even if the temperature becomes the operating start temperature or lower. For this reason, at the time of cold start of the internal combustion engine, it takes a considerable time for the high temperature side heat exchanger to be heated to the predetermined temperature by the exhaust gas, and in particular, the high temperature side heat exchanger is operated as described above. There was a problem that exhaust heat recovery was not performed until the operation start temperature was reached after the stop temperature was exceeded.

  In order to solve such a problem related to the startability of the thermoacoustic engine, a frequency adjuster as disclosed in Patent Document 1 is incorporated to give a forced mechanical vibration to the working fluid in the air column tube. However, there is a drawback that the number of parts and the cost for that purpose are increased.

  An object of the present invention is to provide an exhaust heat recovery device for an internal combustion engine and a method thereof that can improve the start efficiency of the thermoacoustic engine and improve the exhaust heat recovery efficiency.

  The first aspect of the present invention includes an air column tube that is sealed inside and filled with a working fluid, a heat accumulator that is incorporated in the air column tube, and through which the working fluid can pass, and one end portion of which is the heat accumulator. One end side of the exhaust pipe is connected to the air column tube and the other end portion is connected to the exhaust pipe of the internal combustion engine, and exhaust heat of the exhaust gas flowing in the exhaust pipe is recovered and interposed on the one end surface side of the heat accumulator. A heat transfer member for heating the working fluid; and a cooling means for cooling the working fluid interposed on the other end surface side of the heat accumulator, and providing a predetermined temperature gradient between both end surfaces of the heat accumulator. An exhaust heat recovery device for an internal combustion engine having a thermoacoustic engine that generates thermoacoustic self-excited vibration in the working fluid, branching from the middle of the exhaust pipe of the internal combustion engine, and on one end surface side of the heat accumulator A branch pipe penetrating the air column pipe and the heat transfer member, and a front pipe in the branch pipe. Switching means for guiding a part of the exhaust gas flowing in the exhaust pipe and heating the working fluid interposed on one end face side of the heat accumulator through the branch pipe, and thermoacoustic self-excited oscillation of the working fluid starts. It is further characterized by further comprising an operation determination means for determining whether or not the control means and a control means for controlling the operation of the switching means based on a determination result by the determination means.

  In the present invention, the other end portion of the heat transfer member is heated by the exhaust gas flowing in the exhaust pipe of the internal combustion engine, and this heat is transferred to one end portion of the heat transfer member, and the working fluid interposed on the one end surface side of the heat accumulator is Heated. On the other hand, the working fluid intervening on the other end surface side of the regenerator is cooled by the cooling medium supplied from the cooling means, thereby bringing a predetermined temperature gradient between the both end surfaces of the regenerator, and the operation filled in the air column tube Thermoacoustic self-excited vibration is generated in the fluid, and the energy generated by the thermoacoustic self-excited vibration is electrically converted or reconverted thermally and taken out to the outside.

  Immediately after starting the internal combustion engine, if the operation determining means determines whether or not the thermoacoustic self-excited vibration of the working fluid has started, and if it is determined that the thermoacoustic self-excited vibration of the working fluid has not started, the control device The operation of the switching means is controlled so that a part of the exhaust gas flowing in the pipe is guided into the branch pipe, and the working fluid interposed on one end face side of the heat accumulator is heated via the branch pipe, thereby Encourage early generation of acoustic self-excited vibration. After the thermoacoustic self-excited vibration of the working fluid has started in this way, the inside of the branch pipe is closed by the switching means, and the working fluid interposed on the one end face side of the heat accumulator is heated only by heat transfer from the heat transfer member, Maintain the operating state of the thermoacoustic engine.

  In the exhaust heat recovery apparatus for an internal combustion engine according to the first aspect of the present invention, the control means determines the amount of exhaust gas flowing through the exhaust pipe until the operation determining means determines that the thermoacoustic self-excited vibration of the working fluid has started. The switching means may be controlled so that the portion is guided into the branch pipe.

  The switching means has a shutter that can open and close the opening end of the branch pipe facing the exhaust pipe, and this shutter has a guide surface that projects into the exhaust pipe in the open state and guides part of the exhaust gas flowing therethrough into the branch pipe It may be a thing. Alternatively, the switching means may include an on-off valve capable of opening and closing the inside of the branch pipe, and a throttle valve capable of changing a passage cross-sectional area in the exhaust pipe on the downstream side of the opening end of the branch pipe.

  The cooling medium may be cooling water for cooling the internal combustion engine.

  In the second embodiment of the present invention, a heat accumulator capable of passing a working fluid is incorporated in an air column tube hermetically filled with the working fluid, and the working fluid interposed on one end face side of the heat accumulator is used for exhaust heat of the internal combustion engine. And a thermoacoustic engine that cools the working fluid intervening on the other end surface side and gives a predetermined temperature gradient between both end surfaces of the heat accumulator to generate self-excited thermoacoustic vibration in the working fluid. An exhaust heat recovery method for an internal combustion engine, the step of determining whether or not the thermoacoustic self-excited vibration of the working fluid has started after the start of the internal combustion engine, and the determination that the thermoacoustic self-excited vibration of the working fluid has started Until then, a step of guiding a part of the exhaust gas to the one end face side of the heat accumulator is provided.

  In the present invention, the working fluid interposed on the one end surface side of the heat accumulator is heated using the exhaust heat of the internal combustion engine, and the working fluid interposed on the other end surface side of the heat accumulator is cooled, thereby A predetermined temperature gradient is created between both end faces, and the thermoacoustic self-excited vibration is generated in the working fluid filled in the air column tube, and the energy due to the thermoacoustic self-excited vibration is converted electrically or thermally. Reconvert and take it out.

  In this case, after starting the internal combustion engine, it is determined whether the thermoacoustic self-excited vibration of the working fluid has started, and a part of the exhaust gas is removed from the regenerator until it is determined that the thermoacoustic self-excited vibration of the working fluid has started. By leading to the one end surface side, the early generation of the thermoacoustic self-excited vibration of the working fluid is promoted, and after the thermoacoustic self-excited vibration of the working fluid has started, the working fluid interposed on the one end surface side of the regenerator is transferred to the internal combustion engine. The exhaust heat is used to heat and maintain the operating state of the thermoacoustic engine.

  In the exhaust heat recovery method for an internal combustion engine according to the second aspect of the present invention, the step of introducing a part of the exhaust gas to the one end face side of the heat accumulator may be performed a predetermined time after starting the internal combustion engine. . Alternatively, the method further includes a step of detecting the temperature of the exhaust gas purification catalyst and a step of determining whether or not the exhaust gas purification catalyst has reached a temperature at which the exhaust gas purification catalyst is activated. When it has reached, a step of guiding a part of the exhaust gas to the one end face side of the regenerator may be executed.

  By detecting the output of the thermoacoustic engine, it can be determined whether the thermoacoustic self-excited vibration of the working fluid has started. Or it is also possible to determine whether the thermoacoustic self-excited vibration of the working fluid has started based on the temperature difference between the one end side and the other end side of the heat accumulator.

  The working fluid may be cooled by cooling water for cooling the internal combustion engine.

  According to the exhaust heat recovery apparatus for an internal combustion engine of the first aspect of the present invention, the branch pipe branches off from the middle of the exhaust pipe of the internal combustion engine and penetrates the air column pipe and the heat transfer member on one end surface side of the heat accumulator. A switching means for guiding a part of the exhaust gas flowing in the exhaust pipe into the branch pipe and heating the working fluid interposed on one end surface side of the heat accumulator through the branch pipe, and thermoacoustic self-excitation of the working fluid. Since the operation determining means for determining whether or not the vibration has started and the control means for controlling the operation of the switching means based on the determination result by the determining means, the operation determining means is provided with the thermoacoustic function of the working fluid. Until it is determined that excitation vibration has started, the control means controls the switching means so that a part of the exhaust gas flowing in the exhaust pipe is guided into the branch pipe, so that the early stage of the thermoacoustic engine after the start of the internal combustion engine is started. Reliable operation Rukoto it is, it is possible to further improve the exhaust heat recovery efficiency for the internal combustion engine.

  The same effect is obtained by starting the internal combustion engine, determining whether or not the thermoacoustic self-excited vibration of the working fluid has started after the internal combustion engine is started, and starting the thermoacoustic self-excited vibration of the working fluid. Until it is determined that the exhaust gas has been determined, the method of the second aspect of the present invention can be obtained by including a step of leading a part of the exhaust gas to the one end face side of the regenerator.

  The switching means has a shutter that can open and close the opening end of the branch pipe facing the exhaust pipe, and this shutter has a guide surface that projects into the exhaust pipe in an open state and guides a part of the exhaust gas flowing therethrough into the branch pipe In this case, since the shutter itself can have a function as an opening / closing valve of the branch pipe and an introduction member of exhaust gas flowing in the exhaust pipe, an increase in the number of parts can be minimized, and the present invention can be achieved at low cost. Can be realized.

  When the cooling medium is cooling water for cooling the internal combustion engine, or when the working fluid intervening on the other end face side of the regenerator is cooled by the cooling water for cooling the internal combustion engine, it is necessary to add new cooling means. Thus, the present invention can be realized at low cost.

  When a part of the exhaust gas is led to the one end face side of the regenerator after a predetermined time from the start of the internal combustion engine, the exhaust gas is reached after reaching a temperature at which the exhaust gas purification catalyst operates stably without using a temperature sensor or the like. Can be led to one end face side of the regenerator.

  When determining whether the thermoacoustic self-excited vibration of the working fluid has started by detecting the output of the thermoacoustic engine, the thermoacoustic self-excited vibration of the working fluid is easily and reliably detected without using a temperature sensor or the like. You can see that it has started.

  An embodiment of an exhaust heat recovery apparatus for an internal combustion engine according to the present invention will be described in detail with reference to FIGS. 1 to 6, but the present invention is not limited to such an embodiment and is described in the scope of the claims. Any change or modification encompassed by the disclosed concept of the present invention is possible, and can of course be applied to any other technique belonging to the spirit of the present invention.

  The concept of this embodiment is shown in FIG. In other words, the exhaust heat recovery apparatus for an internal combustion engine according to the present embodiment generates power by the thermoacoustic engine 11 using the exhaust heat from the internal combustion engine 10. The thermoacoustic engine 11 includes an air column tube 12 whose inside is sealed and filled with a working fluid such as argon or helium, a heat accumulator 13 which is incorporated in the air column tube 12 and through which the working fluid can pass, A heat transfer member 14 through which the exhaust gas of the internal combustion engine 10 for heating the working fluid interposed on one end surface side of the heat accumulator 13 is guided, and a working fluid interposed on the other end surface side of the heat accumulator 13 is cooled. A low temperature side heat exchanger 15 to which cooling water of the internal combustion engine 10 is guided is provided, and a predetermined temperature gradient is given between both end faces of the heat accumulator 13 to generate thermoacoustic self-excited vibration in the working fluid. .

  On the other hand, in the internal combustion engine 10 of this embodiment for operating the thermoacoustic engine 11, the intake air corresponding to the opening degree of the intake throttle valve 17 is moved from the intake pipe 18 through the intake valve 19 in conjunction with the reciprocating motion of the piston 16. The fuel is sucked into the combustion chamber 20 at a predetermined timing, mixed with the fuel supplied from the fuel injection valve 21 into the combustion chamber 20, ignited by the spark plug 22 and burned, and the exhaust gas is discharged into the exhaust valve 23. Is pushed out from the combustion chamber 20 to the exhaust pipe 24 at a predetermined timing, and passes through an exhaust gas purifying device 25 incorporated in the middle of the exhaust pipe 24 and discharged to the outside. The ignition timing of the spark plug 22, the fuel injection timing by the fuel injection valve 21, the injection amount, and the like are controlled by the control device 26 based on the opening degree of the intake throttle valve 17 and the operating state of the vehicle. The configuration of the internal combustion engine 10 itself is not limited to the present embodiment, and it is needless to say that any conventionally known internal combustion engine 10 can be appropriately employed.

  The air column tube 12 in the present embodiment formed of stainless steel having a circular cross section includes a loop tube portion 12a and a resonance tube portion 12b having a base end connected to the loop tube portion 12a. However, it is not limited to such a structure. The heat accumulator 13, the heat transfer member 14, and the low temperature side heat exchanger 15 described above are incorporated in the loop pipe portion 12a. A sound wave-electric converter 27 that converts an acoustic wave into electric energy is incorporated at the end of the resonance tube portion 12b. A secondary battery 29 mounted on the vehicle is connected to the sonic-electric converter 27 via a stabilization circuit 28 that rectifies the current obtained from the sonic-electric converter 27 and transforms the voltage to a constant level. The electric energy obtained by the thermoacoustic engine 11 is recovered.

  The heat accumulator 13 has a large number of openings extending along the longitudinal direction of the loop pipe portion 12a, through which a working fluid can pass, and a honeycomb structure formed of ceramics or the like Alternatively, a metal net formed of stainless steel or copper or the like, or a so-called metal wool in which a large number of metal fibers such as stainless steel are entangled can be used.

  The cross-sectional structure taken along the line II-II in FIG. 1 is shown in FIG. 2, and the cross-sectional structure taken along the line III-III is shown in FIG. That is, the heat transfer member 14 in this embodiment is formed using stainless steel or the like having excellent heat resistance and corrosion resistance, and slit-like exhaust gas passages 30 are formed at predetermined intervals in a portion where the exhaust pipe 24 is connected. A heat receiving grid portion 31 is defined between the adjacent exhaust gas passages 30 formed to increase the heat receiving area. Similarly, slit-like working fluid passages 32 are formed at predetermined intervals in the portion to which the loop pipe portion 12a is connected, and a radiation grid portion 33 is defined between the adjacent working fluid passages 32 to increase the radiation area. I am planning. A branch pipe 34 having a base end branching from the exhaust pipe 24 upstream of the exhaust gas purification device 25 penetrates the heat radiating grid portion 33 of the heat transfer member 14 so as to cross the heat radiating grid section 33 more directly. 33 can be heated, and a distal end portion of the branch pipe 34 communicates with the exhaust pipe 24 between the proximal end portion of the branch pipe 34 and the exhaust gas purification device 25.

  FIG. 4 schematically shows the extracted enlarged cross-sectional structure of the proximal end portion of the branch pipe 34. That is, a part of the exhaust gas flowing in the exhaust pipe 24 is guided into the branch pipe 34, and the working fluid interposed on the one end face side of the heat accumulator 13 is directly heated via the branch pipe 34. A shutter 35 that can open and close the branch pipe 34 is provided at the open end of the branch pipe 34 facing the front. The shutter 35 is pivotally supported at its base end portion via a pin 36 and opened by an actuator (not shown) whose operation is controlled by the control device 26 so that the tip end protrudes into the exhaust pipe 24. Therefore, a guide surface 35a for guiding a part of the exhaust gas flowing in the exhaust pipe 24 into the branch pipe 34 is provided. In the state indicated by the two-dot chain line in FIG. 4, the open end of the branch pipe 34 is almost completely closed, so that the exhaust gas flowing in the exhaust pipe 24 does not flow into the branch pipe 34 side. Instead of such a shutter 35, an opening / closing valve is provided in the branch pipe 34 as a switching means according to the present invention, a flow rate adjusting valve is provided in the exhaust pipe 24, and the opening / closing of these two valves is controlled. A desired flow rate of exhaust gas may be introduced into the interior.

  The exhaust gas passage 30 formed in the heat transfer member 14 is led to high temperature generated in the internal combustion engine 10, for example, about 500 to 600 ° C. through the exhaust pipe 24, and the exhaust heat is received by the heat receiving grid portion. It collect | recovers in 31 and transmits this to the thermal radiation grid | lattice part 33, heat-exchanges with the working fluid which intervenes in the one end side of the heat accumulator 13 which faces the working fluid channel | path 32, and heats this. However, when the thermoacoustic self-excited vibration of the working fluid has not started after the internal combustion engine 10 is started, the shutter 26 is switched to the open state by the control device 26, and the exhaust gas in the exhaust pipe 24 is transferred from the branch pipe 34 to the heat transfer member. 14 is led to the heat radiating grid portion 33 so that the temperature of the working fluid interposed at one end of the heat accumulator 13 is rapidly raised, and the thermoacoustic self-excited vibration of the working fluid is started and kept in a closed state. It has become.

  The exhaust gas purification device 25 is provided with an exhaust gas temperature sensor 37 for detecting the temperature of the exhaust gas passing through the exhaust gas purification device 25, and the detection signal is output to the control device 26 of the vehicle. It has become.

  A circulating cooling water pipe 38 is led to the low temperature side heat exchanger 15 as a cooling means in the present invention, and heat is exchanged with the working fluid interposed on the other end side of the heat accumulator 13 to exchange it. Cooling. A cooling water circulation pump 39 is incorporated in the middle of the cooling water pipe 38 communicating with the low temperature side heat exchanger 15, and is installed in the vehicle when the temperature of the cooling water in the cooling water pipe 38 exceeds a predetermined temperature. Forcibly cooled by a radiator (not shown) and maintained at a temperature of, for example, approximately 120 ° C. or lower. That is, the temperature of the cooling water supplied to the low temperature side heat exchanger 15 is about 120 ° C. or less at the maximum. In order to detect the temperature of the cooling water flowing in the cooling water pipe 38 also in the middle of the cooling water pipe 38 between the cooling water circulation pump 39 incorporated in the cooling water pipe 38 and the low temperature side heat exchanger 15. A cooling water temperature sensor 40 is attached, and the detection signal is output to the control device 26.

  In this way, a predetermined temperature gradient (in this embodiment, the temperature difference ΔT between both end faces of the heat accumulator 13 is about 380 ° C. or more) is provided between both end faces of the heat accumulator 13, and the resonance tube portion 12b is formed according to a known principle. A self-excited thermoacoustic vibration is caused in the working fluid filled therein.

When the internal combustion engine 10 is started and the thermoacoustic engine 11 is operated, an example of a change in the temperature difference ΔT between both end faces of the heat accumulator 13 at this time is schematically shown in FIG. As is well known, thermoacoustic engine 11 eliminates the thermoacoustic self-excited vibration of the running start temperature difference T _D becomes operational state given thermoacoustic self-excited vibration in the working fluid from the stop state, operating the operational state fluid operation of hysteresis between the stop temperature difference TS, towards the operating stop temperature difference T _S than running start temperature difference T _D is a small value. Accordingly, the shutter 35 is opened immediately after the internal combustion engine 10 is started, and a part of the exhaust gas is directly guided to the heat dissipating grid portion 33 of the heat transfer member 14, so that the heat accumulator 13 is shown as indicated by the solid line in FIG. 4. a temperature difference ΔT between the both end faces can quickly above operation start temperature difference T _D of, once a time thermoacoustic engine 11 is shifted to the operating state (after time t _1), the temperature difference ΔT is unless reduced below stop working temperature difference T _S, thermoacoustic engine 11 is to continue to run. If such measures are not taken, the start of operation of the thermoacoustic engine 11 shifts at time t ₂ as indicated by a broken line, and exhaust heat recovery during this time is not performed.

  In the present embodiment, the shutter 35 is opened after a predetermined time has elapsed since the internal combustion engine 10 was started, and the shutter 35 is closed when power generation of the thermoacoustic engine 11 starts.

This control mode will be described in more detail with reference to the flowchart of FIG. 6. The control device 26 obtains start information of the internal combustion engine 10 from, for example, an ignition key switch on signal, etc., and at a time set in advance in step S1. set the timer, if the count value C of the timer is determined whether or not reached the target value C _R to a preset at S2 in step determines that the predetermined time has elapsed, the shutter and later step S3 35 is opened, a part of the exhaust gas is directly guided from the branch pipe 34 to the heat dissipating grid portion 33 of the heat transfer member 14 to promote the heating of the working fluid interposed at one end side of the heat accumulator 13, and the timer Reset the count value to zero. Then, the process proceeds to step S4, where it is determined whether or not the thermoacoustic engine 11 is generating power based on information from the stabilization circuit 28, and when it is determined that the thermoacoustic engine 11 is generating power. Shifts to the step of S5 and closes the shutter 35, and thereafter, the working fluid intervening at one end side of the heat accumulator 13 is heated using the heat received from the heat receiving grid portion 31 side of the heat transfer member 14.

  In the embodiment described above, the opening and closing of the shutter 35 is controlled according to the timer and the power generation status of the thermoacoustic engine 11, but the shutter 35 is based on information from the exhaust gas temperature sensor 37 and the coolant temperature sensor 40. It is also possible to control the opening and closing of. Further, in the present embodiment, the thermoacoustic engine 11 is used as a generator for recovering exhaust heat of the internal combustion engine 10, but it is naturally possible to use it as a refrigerator of an air conditioner. In this case, it is necessary to further incorporate the high-temperature side and low-temperature side heat exchanger 15 and the heat accumulator 13 into the air column tube 12, which can be achieved by using the technology disclosed in, for example, Japanese Patent No. 3015786. good.

1 is a conceptual diagram illustrating an embodiment of an exhaust heat recovery apparatus for an internal combustion engine according to the present invention. It is II-II arrow sectional drawing in FIG. FIG. 3 is a cross-sectional view taken along arrow III-III in FIG. 2. It is an expanded sectional view of the connection part of an exhaust pipe and a branch pipe in the embodiment shown in FIG. It is a graph which represents typically a time transition of the temperature difference of the one end side and other end side of the thermal accumulator in embodiment shown in FIG. It is a flowchart showing the control process of embodiment shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Thermoacoustic engine 12 Air column pipe 12a Loop pipe part 12b Resonance pipe part 13 Heat accumulator 14 Heat transfer member 15 Low temperature side heat exchanger 16 Piston 17 Intake throttle valve 18 Intake pipe 19 Intake valve 20 Combustion chamber 21 Fuel injection Valve 22 Spark plug 23 Exhaust valve 24 Exhaust pipe 25 Exhaust gas purification device 26 Control device 27 Sonic-electric converter 28 Stabilization circuit 29 Secondary battery 30 Exhaust gas passage 31 Heat receiving lattice portion 32 Working fluid passage 33 Heat radiation lattice portion 34 Branch tube 35 shutter 36 pins 35a guiding surface 37 exhaust gas temperature sensor 38 cooling water pipe 39 cooling water circulation pump 40 the cooling water temperature sensor ΔT heat storage temperature difference between both end surfaces of the unit T _D operation start temperature difference T _S stop working temperature difference t ₁ , T ₂ time

Claims (8)

An air column tube that is sealed inside and filled with a working fluid, a heat accumulator that is incorporated in the air column tube, and through which the working fluid can pass, and one end portion of which is connected to the air column tube at one end of the heat accumulator. The other end is connected to the exhaust pipe of the internal combustion engine, and the heat transfer for recovering the exhaust heat of the exhaust gas flowing through the exhaust pipe and heating the working fluid interposed on the one end face side of the heat accumulator And a cooling means for cooling the working fluid interposed on the other end surface side of the heat accumulator, and a thermoacoustic self-excitation is applied to the working fluid by providing a predetermined temperature gradient between both end surfaces of the heat accumulator. An exhaust heat recovery device for an internal combustion engine comprising a thermoacoustic engine that generates vibration,
A branch pipe branched from the middle of the exhaust pipe of the internal combustion engine, and penetrating the air column pipe and the heat transfer member on one end face side of the heat accumulator;
Switching means for guiding a part of the exhaust gas flowing in the exhaust pipe into the branch pipe and heating the working fluid interposed on one end surface side of the heat accumulator through the branch pipe;
Operation determining means for determining whether or not thermoacoustic self-excited vibration of the working fluid has started;
An exhaust heat recovery apparatus for an internal combustion engine, further comprising: a control unit that controls the operation of the switching unit based on a determination result by the determination unit.   The control means switches the switching means so that a part of the exhaust gas flowing in the exhaust pipe is led into the branch pipe until the operation judging means judges that the thermoacoustic self-excited vibration of the working fluid has started. The exhaust heat recovery device for an internal combustion engine according to claim 1, wherein the exhaust heat recovery device is controlled.   The switching means has a shutter that can open and close the opening end of the branch pipe facing the exhaust pipe, and the shutter projects into the exhaust pipe in an open state, and a part of the exhaust gas flowing therethrough is passed through the branch pipe. An exhaust heat recovery apparatus for an internal combustion engine according to claim 1 or 2, further comprising a guide surface that leads to the internal combustion engine.   The exhaust heat recovery apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the cooling medium is cooling water for cooling the internal combustion engine. A heat accumulator through which the working fluid can pass is incorporated in an air column tube hermetically filled with the working fluid, and the working fluid interposed on one end face side of the heat accumulator is heated using the exhaust heat of the internal combustion engine and on the other end face side. An exhaust heat recovery method for an internal combustion engine comprising a thermoacoustic engine that cools an intervening working fluid and gives a predetermined temperature gradient between both end faces of the heat accumulator to generate self-excited thermoacoustic vibration in the working fluid. And
Determining whether thermoacoustic self-excited vibration of the working fluid has started after starting the internal combustion engine;
And a step of guiding a part of the exhaust gas to one end face side of the heat accumulator until it is determined that the thermoacoustic self-excited vibration of the working fluid has started.   6. The exhaust heat recovery method for an internal combustion engine according to claim 5, wherein the step of guiding a part of the exhaust gas to the one end face side of the heat accumulator is performed after a predetermined time from the start of the internal combustion engine.   The exhaust of the internal combustion engine according to claim 5 or 6, wherein whether or not the thermoacoustic self-excited vibration of the working fluid has started is determined by detecting an output of the thermoacoustic engine. Heat recovery method.   The exhaust heat recovery method for an internal combustion engine according to any one of claims 5 to 7, wherein the working fluid is cooled by cooling water for cooling the internal combustion engine.

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