JP4337630B2 - Stirling engine failure diagnosis device - Google Patents

Description

The present invention relates to a fault diagnosis equipment of the Stirling engine, in particular, is not required, such as a torque meter or acupressure meter, a simple device configuration, it is possible to perform failure diagnosis of the Stirling engine, the Stirling engine failure diagnosis instrumentation about the location.

  In recent years, Stirling engines with excellent theoretical thermal efficiency have attracted attention as external combustion engines that recover exhaust heat from internal combustion engines and factory exhaust heat mounted on vehicles such as passenger cars, buses, and trucks.

Japanese Patent Laying-Open No. 2002-266701 (Patent Document 1) discloses that a Stirling engine is provided in an exhaust system of an internal combustion engine.
Japanese Patent Laid-Open No. 2002-115574 (Patent Document 2) discloses a method for estimating the output of a Rankine cycle device provided in an engine exhaust system based on the product of exhaust gas energy and exchange efficiency. Yes.

JP 2002-266701 A JP 2002-115574 A JP-A-1-247747 Japanese Utility Model Publication No. 63-183358

There is a demand for fault diagnosis of external combustion engines. However, an effective device for diagnosing failure of an external combustion engine has not been disclosed .

An object of the present invention is to provide a failure diagnosis apparatus for an external combustion engine .

The failure diagnosis device for a Stirling engine according to the present invention includes the temperature and flow rate of the exhaust gas of the internal combustion engine before the heat energy is recovered by the Stirling engine provided in the exhaust system of the internal combustion engine, based on a temperature estimation means for estimating the temperature of the exhaust gas of the internal combustion engine after the heat energy has been recovered by the Stirling engine, the exhaust gas of the internal combustion engine after the heat energy has been recovered by the Stirling engine a temperature measuring means for measuring the temperature of said estimated temperature, based on the measured temperature, characterized in that a fault diagnosis means for performing a fault diagnosis of the Stirling engine.

According to the present invention described above, failure diagnosis of a Stirling engine can be performed with a simple device configuration without the need for a torque meter or a tonometer.
Further, since the amount of heat energy not recovered by the Stirling engine is estimated from the heat energy input to the Stirling engine and the heat energy recovered by the Stirling engine, the estimation accuracy is improved.
Further, according to the present invention, the temperature of the exhaust gas heat medium of the internal combustion engine after the recovery of the thermal energy is determined based on the rotational speed of the Stirling engine indicating the recovery status of the thermal energy from the exhaust gas of the internal combustion engine. Since the estimation is performed, the estimation accuracy is improved.

In the Stirling engine failure diagnosis apparatus according to the present invention, the temperature of the exhaust gas of the internal combustion engine before the recovery of the thermal energy is estimated based on the rotational speed and load torque of the internal combustion engine .

  In the failure diagnosis apparatus for an external combustion engine according to the present invention, the failure diagnosis means is configured such that when the absolute value of the difference between the estimated temperature and the measured temperature exceeds a predetermined value, the external combustion engine It is characterized by diagnosing a failure.

  In the failure diagnosis apparatus for an external combustion engine according to the present invention, when it is diagnosed that the external combustion engine has failed, the fact is notified.

The Stirling engine failure diagnosis apparatus according to the present invention can diagnose a Stirling engine failure with a simple device configuration.

  Hereinafter, an embodiment of the Stirling engine of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a front view showing a Stirling engine of the present embodiment. As shown in FIG. 1, the Stirling engine of this embodiment is an α-type (two-piston type) Stirling engine 10 and includes two power pistons 20 and 30. The two power pistons 20 and 30 are arranged in parallel in series. As shown in FIG. 6, the piston 31 of the low temperature side power piston 30 has a phase difference so as to move with a delay of about 90 ° in crank angle with respect to the piston 21 of the high temperature side power piston 20.

  The working fluid heated by the heater 47 flows into the space (expansion space) above the cylinder (hereinafter referred to as the high temperature side cylinder) 22 of the high temperature side power piston 20. The working fluid cooled by the cooler 45 flows into the space (compression space) above the cylinder (hereinafter referred to as the low temperature side cylinder) 32 of the low temperature side power piston 30.

  The regenerator (regenerative heat exchanger) 46 stores heat when the working fluid reciprocates between the expansion space and the compression space. That is, when the working fluid flows from the expansion space to the compression space, the regenerator 46 receives heat from the working fluid, and when the working fluid flows from the compression space to the expansion space, passes the stored heat to the working fluid.

  As the two pistons 21 and 31 reciprocate, the reciprocating flow of the working gas occurs, and the ratio of the working fluid in the expansion space of the high temperature side cylinder 22 and the compression space of the low temperature side cylinder 32 changes. As it changes, pressure fluctuations occur. Comparing the pressures when the two pistons 21 and 31 are in the same position, the expansion piston 21 is considerably higher when it is lowered than when it is raised, and the compression piston 31 is lower. For this reason, the expansion piston 21 needs to perform a large positive work (expansion work) with respect to the outside, and the compression piston 31 needs to receive work (compression work) from the outside. Part of the expansion work is used for compression work, and the rest is taken out as an output via the drive shaft 40.

  As shown in FIG. 2, the Stirling engine 10 of this embodiment is used together with a main engine (gasoline engine, internal combustion engine) 200 in a vehicle to constitute a hybrid system. That is, the Stirling engine 10 is an exhaust heat recovery device that uses the exhaust gas of the main engine 200 as a heat source. The heater 47 of the Stirling engine 10 is disposed inside the exhaust pipe 100 of the main engine 200 of the vehicle, and the working fluid is heated by the thermal energy recovered from the exhaust gas, so that the Stirling engine 10 is operated.

  The Stirling engine 10 of the present embodiment is installed in a limited space in the vehicle such that the heater 47 is accommodated in the exhaust pipe 100, so that the installation of the Stirling engine 10 is more compact if the entire device is compact. The degree increases. For this purpose, the Stirling engine 10 employs a configuration in which the two cylinders 22 and 32 are arranged in series and not in a V shape.

  When the heater 47 is disposed inside the exhaust pipe 100, the heater 47 is placed on the upstream side (the side close to the main engine 200) 100 a of the exhaust gas in which a relatively high-temperature exhaust gas flows inside the exhaust pipe 100. The high temperature side cylinder 22 side of the heater 47 is located, and the low temperature side cylinder 32 side of the heater 47 is located on the downstream side (the side far from the main engine 200) 100b through which relatively low temperature exhaust gas flows. This is because the high temperature side cylinder 22 side of the heater 47 is heated more.

  Each of the high temperature side cylinder 22 and the low temperature side cylinder 32 is formed in a cylindrical shape and supported by a substrate 42 which is a reference body. In the present embodiment, the substrate 42 serves as a position reference for each component of the Stirling engine 10. With this configuration, the relative positional accuracy of each component of the Stirling engine 10 is ensured. In addition, the substrate 42 can be used as a reference when the Stirling engine 10 is attached to the exhaust pipe (exhaust passage) 100 or the like that is the target of heat recovery.

  A substrate 42 is fixed to the flange 100f of the exhaust pipe 100 via a heat insulating material (spacer, not shown). A flange 22 f provided on a side surface (outer peripheral surface) 22 c of the high temperature side cylinder 22 is fixed to the substrate 42. Further, a flange 46 f provided on a side surface (outer peripheral surface) 46 c of the regenerator 46 is fixed to the substrate 42.

  The exhaust pipe 100 and the Stirling engine 10 are attached via a substrate 42. At this time, the substrate 42 and the end surface on the side where the heater 47 is connected in the high temperature side cylinder 22 (upper surface of the top portion 22b), and the end surface on the side where the cooler 45 is connected in the low temperature side cylinder 32 (top surface 32a). And the Stirling engine 10 are attached to the substrate 42 so that they are substantially parallel to each other. Alternatively, the Stirling engine 10 is configured such that the substrate 42 and the rotation axis of the crankshaft 61 (or the drive shaft 40) are parallel, or the central axis of the exhaust pipe 100 and the rotation axis of the crankshaft 61 are parallel. Is attached to the substrate 42. Thereby, the Stirling engine 10 can be easily attached to the exhaust pipe 100 without making a significant design change to the existing exhaust pipe 100. As a result, the Stirling engine 10 can be mounted on the exhaust pipe 100 without impairing the performance, mountability, noise, and other functions of the internal combustion engine body of the vehicle that is the subject of exhaust heat recovery. Further, even when the Stirling engine 10 having the same specification is attached to different exhaust pipes, it can be dealt with only by changing the specification of the heater 47, so that versatility can be improved.

  The Stirling engine 10 is placed horizontally in a space adjacent to the exhaust pipe 100 arranged under the floor of the vehicle, that is, each of the high temperature side cylinder 22 and the low temperature side cylinder 32 with respect to the vehicle floor (not shown). The two pistons 21 and 31 are reciprocated in the horizontal direction. In the present embodiment, for convenience of explanation, it is assumed that the top dead center side of the two pistons 21 and 31 is upward and the bottom dead center side is downward.

  The higher the average pressure (Pmean described later) of the working fluid, the higher the pressure difference with respect to the same temperature difference due to the cooler 45 and the heater 47, so a higher output is obtained. Therefore, as described above, the working fluid in the high temperature side cylinder 22 and the low temperature side cylinder 32 is maintained at a high pressure.

  The pistons 21 and 31 are formed in a cylindrical shape. A small clearance of several tens of μm is provided between the outer peripheral surfaces of the pistons 21 and 31 and the inner peripheral surfaces of the cylinders 22 and 32. The working fluid (air) of the Stirling engine 10 is included in the clearances. Intervene. The pistons 21 and 31 are supported in a non-contact state by air bearings 48 with respect to the cylinders 22 and 32, respectively. Therefore, the piston ring is not provided around the pistons 21 and 31, and the lubricating oil generally used with the piston ring is not used. However, a fixed lubricant is attached to the inner peripheral surfaces of the cylinders 22 and 32. The sliding resistance of the working fluid of the air bearing 48 is originally extremely low, but a fixed lubricant is added to further reduce it. As described above, the air bearing 48 keeps the airtightness of the expansion space and the compression space with the working fluid (gas), and performs clearance sealing without ring and without oil.

  The heater 47 has a plurality of heat transfer tubes (tube groups) 47t, and the plurality of heat transfer tubes 47t are formed in a substantially U-shape. A first end portion 47ta of each heat transfer tube 47t is connected to an upper portion (top portion) (end surface on the top surface 22a side) 22b of the high temperature side cylinder 22. A second end portion 47tb of each heat transfer tube 47t is connected to an upper portion (end surface on the heater 47 side) 46a of the regenerator 46. The reason why the heater 47 is generally U-shaped as described above will be described later.

  The regenerator 46 includes a heat storage material (matrix, not shown) and a regenerator housing 46h in which the matrix is accommodated. Since the high-pressure working fluid enters the regenerator housing 46h, the regenerator housing 46h is a pressure vessel. In the regenerator 46, a laminated wire mesh is used as a matrix.

  The following conditions are required for the regenerator 46 from the above-described functions. That is, the heat transfer performance and the heat storage capacity are high, the flow resistance (flow loss, pressure loss) is small, the thermal conductivity in the flow direction of the working fluid is small, and a large temperature gradient is required. The wire mesh material can be stainless steel. When passing through the mesh of each laminated wire mesh, the heat of the working fluid is stored in the wire mesh.

  In the heater 47, the connection portion (cross-sectional shape) with the high temperature side cylinder 22 has the same shape and size as the opening shape (perfect circle) of the upper portion (connection portion with the heater 47) of the high temperature side cylinder 22. . Similarly, the connecting portion of the heater 47 to the regenerator 46 has the same shape and size as the upper surface of the regenerator 46. That is, the sectional shapes of the heater 47 and the regenerator 46 are formed in the same shape and size as the opening shapes of the high temperature side cylinder 22 and the low temperature side cylinder 32. With this configuration, the flow resistance (flow resistance) of the working fluid is reduced.

  In the present embodiment, a space can be secured without affecting the vertical size of the entire Stirling engine 10 in order to minimize the influence of the counterweight 90 on the vertical size of the entire Stirling engine 10. A counterweight 90 is provided on the high temperature side cylinder 22 side.

  Next, an output estimation method of the Stirling engine 10 will be described.

As shown in FIG. 2, an internal combustion engine (main engine) 200, and an exhaust gas amount G _E of the main engine 200, the engine speed N _E, the torque Torque _E is sought. Exhaust gas amount G _E can be obtained based on the intake air amount and the fuel consumption of the main engine 200.

  As shown in FIG. 1, in the exhaust pipe 100, a temperature sensor T1 is provided on the exhaust gas upstream side (side closer to the main engine 200) 100a than the position where the Stirling engine 10 is provided, and the downstream side 100b. Is provided with a temperature sensor T2. The crankcase is provided with a rotation speed sensor Ns in the vicinity of a passing position of a counterweight 90 provided on the crankshaft 61. Hereinafter, the temperature detected by the temperature sensor T1 is defined as temperature T1, the temperature detected by the temperature sensor T2 is defined as temperature T2, and the rotational speed detected by the rotational speed sensor Ns is defined as rotational speed Ns.

  The temperature T <b> 1 is the temperature of the exhaust gas supplied to the Stirling engine 10. The temperature T <b> 2 is the temperature of the exhaust gas after being used as a heat source for the Stirling engine 10. The rotation speed Ns is the rotation speed of the Stirling engine 10.

From the exhaust gas temperatures T1 and T2 before and after the Stirling engine 10 and the exhaust gas amount G _E of the main engine 200, the heat input amount Qin to the Stirling engine 10 is obtained from the following equation 1.

Next, as shown in the following Equation 2, the output of the Stirling engine 10 is obtained by multiplying the heat input Qin by the efficiency inherent in the Stirling engine 10.

The intrinsic efficiencies η _i , η _R , and η _m in the above equation [Equation 2] are functions as a function of temperature (T1, T2), the rotational speed Ns of the Stirling engine 10, the average working gas pressure Pmean (≈ crankcase pressure), and the like. Alternatively, it is obtained in advance as a map. The illustrated efficiency η _i corresponds to the theoretical efficiency of the cycle determined by specifications (specifications) such as the compression ratio of the Stirling engine 10.

  Here, the average working gas pressure Pmean will be described with reference to FIG.

  FIG. 6 shows changes in the top surface position of the high temperature side piston 21 and the top surface position of the low temperature side piston 31. As described above, the low temperature side piston 31 has a phase difference so as to move 90 ° behind the high temperature side piston 21 with a crank angle. In FIG. 6, a combined wave W of the waveform of the high temperature side piston 21 and the waveform of the low temperature side piston 31 indicates the in-cylinder pressure. In FIG. 6, the symbol Pmax indicates the maximum value (maximum compression pressure) of the in-cylinder pressure during the compression process. Symbol Pmean indicates the average working gas pressure, which is an average value of the in-cylinder pressure.

  The output of the Stirling engine 10 can be estimated by the above equations [Equation 1] and [Equation 2]. In this case, the output of the Stirling engine 10 can be estimated with a simple device configuration using only the thermometers T1 and T2 without using a torque meter or a tonometer.

The temperature sensor T1 can be omitted. Temperature T1, the rotational speed N _E of the main engine 200, as a function of the load torque Torque _E, or can be determined in advance as a map. Temperature T1, the engine speed N _E, the relationship between the load torque Torque _E, is shown in FIG.

Further, the temperature sensor T2 can be omitted. The temperature T2 can be obtained in advance as a function or a map of the temperature T1, the exhaust gas amount G _E of the main engine 200, and the rotational speed Ns of the Stirling engine 10. Thus, the estimated value of the temperature T2 obtained by the above function or map without using the temperature sensor T2 is denoted as temperature T2s. The relationship among the temperature T2s, the temperature T1, the exhaust gas amount G _E of the main engine 200, and the rotational speed Ns of the Stirling engine 10 is as shown in FIG.

Here, the exhaust gas amount G _E and the temperature T1 of the main engine 200 correspond to the input energy to the Stirling engine 10, the rotational speed Ns of the Stirling engine 10 corresponds to the recovered energy of the Stirling engine 10, and the estimated temperature T2s. Corresponds to unrecovered energy even in the Stirling engine 10. That is, the unrecovered energy (T2s) of the Stirling engine 10 is estimated from the input energy (G _E , temperature T1) to the Stirling engine 10 and the recovered energy (Ns) of the Stirling engine 10, thereby improving the estimation accuracy. To do.

  In the above description, as a parameter used for estimating the temperature T2, an index value determined by the rotational speed Ns of the Stirling engine 10 and the average working gas pressure Pmean is used instead of the rotational speed Ns of the Stirling engine 10. it can.

  From the above, the temperature sensor T1 and the temperature sensor T2 are omitted, and the output of the Stirling engine 10 is calculated using the above [Equation 1] and [Equation 2] based on the estimated value of the temperature T1 and the estimated temperature T2s. Can be estimated.

  When the output of the Stirling engine 10 estimated as described above is used as part of the power of the vehicle, the output of the main engine 200 is corrected by the estimated output of the Stirling engine 10.

  Next, a failure diagnosis method for the Stirling engine 10 will be described with reference to FIG.

[Step S1]
First, the exhaust gas amount G _E of the main engine 200, the temperature T1, the temperature T2, and the rotational speed Ns of the Stirling engine 10 are measured. In this case, the temperature T1 may be an estimated value. Next, step S2 is performed.

[Step 2]
Then, measured in the step 1, the exhaust gas amount G _E of the main engine 200, and the temperature T1, the temperature T2, based on the rotation speed Ns of the Stirling engine 10 (time change) of, at steady state It is determined whether or not there is. As a result of the determination, the determination in step S2 is repeated until it is determined that the steady state is reached. Step S3 is performed when it is determined that it is in a steady state.

[Step S3]
Next, in step S3, T2s is determined based on the measured values of the exhaust gas amount G _E of the main engine 200, the temperature T1, and the rotational speed Ns of the Stirling engine 10 after the determination of the steady state in step S2. Is estimated. As described above, the estimation is performed based on the relationship shown in FIG.

[Step S4]
Next, the difference between the estimated value T2s and the actually measured temperature T2 (the value of the temperature T2 used for the estimation in step S3) is taken. If the difference is larger than a preset value K, it is determined that a failure has occurred in the Stirling engine 10. In that case, if the absolute value of the difference between the estimated value T2s and the measured value T2 is greater than the value K, it is determined that there is a failure.

  As a result of step S4, when it is determined that there is a failure (abnormal), an alarm can be issued or a control guard can be applied to the Stirling engine 10.

  In the above-described method for estimating the output of the Stirling engine 10 and the failure diagnosis method for the Stirling engine 10, if the detected value by each sensor is a value with a large fluctuation before the steady state (transient state) is used as it is. Therefore, since accurate output estimation and failure diagnosis cannot be performed, the value after the steady state is used. In this case, it can be determined that the detected value is in a steady state when the amount of change per unit time is equal to or less than a predetermined value.

  The output estimation method of Stirling engine 10 and the failure diagnosis method of Stirling engine 10 described above can be applied when an external combustion engine other than the Stirling engine is used for exhaust heat recovery.

  Next, the reason why the heater 47 is formed in a substantially U shape (curved shape) as described above will be described.

  The heat source of the Stirling engine 10 is the exhaust gas of the main engine 200 of the vehicle as described above, and is not a heat source specially prepared for the Stirling engine. Therefore, the heat quantity is not so high, and the Stirling engine 10 needs to operate with the heat quantity of the exhaust gas, for example, about 800 ° C. Therefore, the heater 47 of the Stirling engine 10 needs to receive heat efficiently from the exhaust gas in the exhaust pipe 100.

  The volume of the heat exchanger composed of the heater 47, the regenerator 46, and the cooler 45 is an invalid volume that is not directly related to the output. When the volume of the heat exchanger increases, the output of the Stirling engine 10 increases. Decrease. On the other hand, if the volume of the heat exchanger is made compact, heat exchange becomes difficult correspondingly, the amount of heat received decreases, and the output of the Stirling engine 10 decreases. For these reasons, it is necessary to increase the efficiency of the heat exchanger in order to achieve both a decrease in the ineffective volume and an increase in the amount of heat received. Therefore, the heater 47 needs to receive heat efficiently.

  In order to efficiently receive heat from the exhaust gas in the exhaust pipe 100 and efficiently exchange heat, all the heaters 47 are accommodated in the exhaust pipe 100 without being excessive and insufficient, and cooled so as not to receive heat from the exhaust gas. The structure which takes out the container 45 out of the exhaust pipe 100 is required. For this reason, when the flange 100f to which the Stirling engine 10 is attached in the exhaust pipe 100 is used as a reference, the attachment position of the low temperature side cylinder 32 is lower than the high temperature side cylinder 22 by at least the height of the cooler 45. That is, the position of the compression space formed in the upper part of the low temperature side cylinder 32 is lower than the position of the expansion space formed in the upper part of the high temperature side cylinder 22, and the top dead center of the compression piston 31 is the expansion piston 21. The position is lower than the position of the top dead center.

  In the present embodiment, in order to change the positions of the top dead centers of the compression piston 31 and the expansion piston 21, extension portions (piston struts) having different lengths are provided between the piston pins 60a and 60b and the pistons 31 and 21, respectively. Part) It is connected with 64b and 64a. The extension part 64 a connected to the expansion piston 21 is higher than the extension part 64 b connected to the compression piston 31 by the amount that the position of the top dead center of the expansion piston 21 is higher than the position of the top dead center of the compression piston 31. Is too long.

  In the present embodiment, the height of the expansion piston 21 itself and the compression piston 31 itself (the distance between the upper surfaces of the pistons 21 and 31 and the connection points 21c and 31c between the extensions 64a and 64b of the pistons 21 and 31). Are configured to be the same, and the positions of the top dead centers of the pistons 21 and 31 are changed using the extension portions 64a and 64b having different lengths. Instead of this configuration, the length of the extension itself is the same on the expansion piston side and the compression piston side, and the expansion piston and the compression piston are configured to change the height of the expansion piston itself and the compression piston itself. It is also possible to adopt a configuration that changes the position of the top dead center. The technical significance of increasing the vertical length of the expansion piston itself as compared with the compression piston itself will be described next.

  In order to suppress a decrease in the efficiency of the Stirling engine 10, a space other than the expansion space in the high temperature side power piston 20 and a space other than the compression space in the low temperature side power piston 30, that is, the high temperature side power piston 20 and the low temperature side power piston. The space around the crankshaft 61 in each of the 30 needs to be kept at room temperature. Therefore, the high temperature working fluid in the expansion space flows into the space around the high temperature side power piston 20 of the crankshaft 61, or the low temperature working fluid in the compression space is around the low temperature side power piston 30 side of the crankshaft 61. It is necessary to securely seal the high temperature side cylinder 22 and the expansion piston 21 and the low temperature side cylinder 32 and the compression piston 31 so as not to flow into the space. Air bearing 48 is used).

  On the other hand, as described above, since the top portion 22b and the upper portion of the side surface 22c of the high temperature side cylinder 22 are accommodated in the exhaust pipe 100 in order to increase the temperature of the expansion space, the upper portion of the high temperature side cylinder 22 and the expansion piston are accommodated. The upper part of 21 expands thermally. There is a possibility that sealing cannot be reliably performed in the portions of the high temperature side cylinder 22 and the expansion piston 21 which are thermally expanded. Therefore, as described above, the lengths of the expansion piston 21 and the high temperature side cylinder 22 in the vertical direction are set long, thereby providing a temperature gradient in the vertical direction of the expansion piston 21 to influence the influence of thermal expansion. It is possible to ensure that sealing is performed at a portion not received (lower portion of the expansion piston 21). In addition, since the space between the high temperature side cylinder 22 and the expansion piston 21 is sealed at the lower portion of the expansion piston 21 (the portion that is not affected by thermal expansion), the movement distance of the seal portion is sufficiently secured for expansion. In order to sufficiently compress the space, the length in the vertical direction of the high temperature side cylinder 22 can be set long.

  Regardless of the type of heat source, in order to receive heat efficiently from the heat source and efficiently exchange heat, the heater has a large heat transfer area for receiving heat energy and the cooler receives heat. The configuration of the above-described embodiment is desirable in the sense that it can be placed in a place that does not.

  In particular, when exhaust heat is used, heat energy is often supplied as exhaust gas through a pipe, and therefore, a heat-receivable region such as the inside of the pipe is limited. In this case, the configuration of the Stirling engine 10 described above is excellent as a configuration in which the heat transfer area is as large as possible and the cooler is not received heat. The technical significance of the configuration of the Stirling engine 10 will be further described below.

  As described above, it is preferable that the ineffective volume portion (cooler, regenerator, heater) is small. However, when the ineffective volume portion has a curved shape, the flow path is increased when the number of the curved portions is large. If the resistance increases and the curvature of the curved portion is small, the flow path resistance increases. That is, when the pressure loss of the working fluid is taken into consideration, it is better that the number of curved portions is single and the curvature is large. In this regard, the heater 47 is generally U-shaped and has a curved shape, but the number of curved portions is one. The cooler 45 is configured to have a curved portion in order to reduce the size of the Stirling engine 10 (shortening the vertical dimension), and has the above-described characteristics.

  Further, as shown in FIG. 1, regarding the curvature of the ineffective volume portion of the above embodiment, the upper portions of two cylinders 22 and 32 arranged in series are connected to each other, and the working fluid is contained inside the exhaust pipe 100. The vertical height between the top portion 22b of the high temperature side cylinder 22 and the upper surface 46a of the regenerator 46, and the upper inner surface of the exhaust pipe 100, which are set substantially on the same plane to suppress an increase in flow resistance, and the heater The curvature (curve shape) is set in accordance with a configuration in which the heights between the end portions 47ta and 47tb of 47 and the uppermost portion of the central portion 47c are substantially the same height h. In order to ensure a large contact area with a heat source of a fluid such as exhaust gas in a limited space such as the inside of the exhaust pipe 100, a curved shape as described above is desirable.

  From the above viewpoint, the heater of the ineffective volume portion is housed in a limited space (heat receiving space) that receives heat from a heat source such as the inside of the exhaust pipe, and in the heat receiving space. Therefore, it is preferable that the heat transfer area from the heat source is configured to have a curved shape such as a U shape or a J shape so that the heat transfer area can be maximized and the flow resistance is minimized.

  In order to arrange the regenerator 46 while minimizing the flow resistance of the working fluid, the regenerator 46 is linearly formed (on the same axis) along the extending direction (axial direction) of the low temperature side cylinder 32. As described above, the regenerator 46 connected to the second end 47tb of the heater 47 is provided along the extending direction of the low temperature side cylinder 32. The first end 47ta of the heater 47 is connected to the upper portion of the high temperature side cylinder 22 without a gap. For these reasons, at least the first end portion 47ta and the second end portion 47tb of the heater 47 have portions along the extending direction of the high temperature side cylinder 22 and the low temperature side cylinder 32, respectively. The central portion 47c often has a curved shape as described above.

  For the technical reasons described above, the heater 47 is configured to change its direction (turn) in the middle between the two cylinders 22 and 32 arranged in series and parallel. The heater 47 has a curved portion connecting the two cylinders 22 and 32 arranged in series and parallel.

  Next, the piston / cylinder seal structure and the piston / crank mechanism will be described.

  As described above, since the heat source of the Stirling engine 10 is the exhaust gas of the internal combustion engine of the vehicle, the amount of heat obtained is limited, and it is necessary to operate the Stirling engine 10 within the range of the obtained heat amount. Therefore, in this embodiment, the internal friction of the Stirling engine 10 is reduced as much as possible. In this embodiment, in order to eliminate the friction loss due to the piston ring having the largest friction loss among the internal friction of the Stirling engine, the piston ring is not used, and instead, between the cylinders 22 and 32 and the pistons 21 and 31. Each is provided with an air bearing 48.

  Since the air bearing 48 has extremely small sliding resistance, the internal friction of the Stirling engine 10 can be greatly reduced. Even if the air bearing 48 is used, since the airtightness between the cylinders 22 and 32 and the pistons 21 and 31 is ensured, there is no problem that a high-pressure working fluid leaks during expansion and contraction.

  The air bearing 48 is a bearing in which the pistons 21 and 31 are floated in the air using the pressure (distribution) of air generated by a minute clearance between the cylinders 22 and 32 and the pistons 21 and 31. In the air bearing 48 of the present embodiment, the diameter clearance between the cylinders 22 and 32 and the pistons 21 and 31 is several tens of μm. In order to realize an air bearing that floats an object in the air, in addition to forming a portion (pressure gradient) where the air pressure is mechanically increased, high-pressure air may be blown as described later.

  In the present embodiment, an air bearing having the same configuration as that of an air bearing used between a cylinder and a piston of a medical glass syringe is used instead of an air bearing that blows high-pressure air.

  Further, since the use of the air bearing 48 eliminates the need for the lubricating oil used in the piston ring, there is no problem that the heat exchanger (the regenerator 46 and the heater 47) of the Stirling engine 10 deteriorates due to the lubricating oil. . In the present embodiment, it is sufficient to eliminate the problem of sliding resistance and lubricating oil in the piston ring. Therefore, the gas bearing excluding the oil bearing that uses oil in the fluid bearing is limited to the air bearing 48. It can be applied without being done.

  It is also possible to use a static pressure air bearing between the pistons 21 and 31 and the cylinders 22 and 32 of the present embodiment. The static pressure air bearing is a device in which a pressurized fluid is ejected and an object (the pistons 21 and 31 in this embodiment) is levitated by the generated static pressure. Further, it is possible to use a dynamic pressure air bearing instead of the static pressure air bearing.

  When the pistons 21 and 31 are reciprocated in the cylinders 22 and 32 using the air bearing 48, the linear motion accuracy must be less than the diameter clearance of the air bearing 48. Further, since the load capacity of the air bearing 48 is small, the side forces of the pistons 21 and 31 must be substantially zero. That is, since the air bearing 48 has a low ability (pressure resistance ability) to withstand the force in the diameter direction (lateral direction, thrust direction) of the cylinders 22 and 32, the linear motion accuracy of the pistons 21 and 31 with respect to the axes of the cylinders 22 and 32 is low. Need to be expensive. In particular, the air bearing 48 of the type that is used in the present embodiment and is supported by levitating using a fine clearance air pressure has a low pressure resistance against the force in the thrust direction compared to the type that blows high-pressure air. Higher linear motion accuracy of the piston is required.

  For this reason, in this embodiment, the grasshopper mechanism (approximate linear link) 50 is employed in the piston / crank portion. The glass hopper mechanism 50 is smaller in size than the other linear approximation mechanism (for example, a watt mechanism), so that the size of the mechanism necessary for obtaining the same linear motion accuracy is small. It is done. In particular, the Stirling engine 10 according to the present embodiment is installed in a limited space such that the heater 47 is accommodated in the exhaust pipe of an automobile. The degree increases. Further, the grasshopper mechanism 50 is advantageous in terms of fuel consumption because the weight of the mechanism necessary for obtaining the same linear motion accuracy is lighter than other mechanisms. Furthermore, the grasshopper mechanism 50 is easy to configure (manufacture / assemble) because the structure of the mechanism is relatively simple.

  FIG. 7 shows a schematic configuration of the piston / crank mechanism of the Stirling engine 10. In the present embodiment, since the piston / crank mechanism adopts a common configuration for the high temperature side power piston 20 side and the low temperature side power piston 30 side, only the low temperature side power piston 30 side will be described below. Description of the high temperature side power piston 20 side is omitted.

  As shown in FIGS. 7 and 1, the reciprocating motion of the compression piston 31 is transmitted to the drive shaft 40 by the connecting rod 109, where it is converted into rotational motion. The connecting rod 109 (65a, 65b) is supported by the approximate linear mechanism 50 shown in FIG. 7, and reciprocates the low temperature side cylinder 32 linearly. Thus, by supporting the connecting rod 109 by the approximate linear mechanism 50, the side force F of the compression piston 31 becomes almost zero, so that the compression piston 31 can be sufficiently supported by the air bearing 48 having a small load capacity. it can.

It is positive (cross) plane view showing a Stirling engine of the first embodiment of the fault diagnosis apparatus of the Stirling engine of the present invention. It is a top view which shows the attachment state of the Stirling engine and internal combustion engine of 1st Embodiment of the failure diagnosis apparatus of the Stirling engine of this invention. It is the graph which showed the relationship between the temperature T1 of 1st Embodiment of the failure diagnosis apparatus of the Stirling engine of this invention, the rotation speed of an internal combustion engine, and load torque. It is the graph which showed the relationship between the temperature T2 of 1st Embodiment of the failure diagnosis apparatus of the Stirling engine of this invention, the temperature T1, the rotation speed of a Stirling engine, and the amount of exhaust gas of an internal combustion engine. 5 is a flowchart illustrating a failure diagnosis method in the first embodiment of the failure diagnosis device for a Stirling engine according to the present invention. It is a graph explaining the cylinder pressure of 1st Embodiment of the exhaust heat recovery apparatus of this invention. It is explanatory drawing for demonstrating the linear approximation mechanism applied in 1st Embodiment of the exhaust heat recovery apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stirling engine 20 High temperature side power piston 21 Expansion piston 22 High temperature side cylinder 22a Upper surface of high temperature side cylinder 30 Low temperature side power piston 31 Compression piston 32 Low temperature side cylinder 40 Drive shaft 45 Cooler 46 Regenerator 47 Heater 47ta 1st end part 47tb second end 50 approximate linear mechanism 61 crankshaft 64a, 64b extension 65a, 65b connecting rod 90 counterweight (balance weight)
100 exhaust pipe 200 main engine T1 temperature T2 temperature Ns rotation speed

Claims (4)

Based on the temperature and flow rate of the exhaust gas of the internal combustion engine before the heat energy is recovered by the Stirling engine provided in the exhaust system of the internal combustion engine and the rotational speed of the Stirling engine , the thermal energy is generated by the Stirling engine. Temperature estimating means for estimating the temperature of the exhaust gas of the internal combustion engine after being recovered;
Temperature measuring means for measuring the temperature of the exhaust gas of the internal combustion engine after the thermal energy is recovered by the Stirling engine ;
A failure diagnosis device for a Stirling engine , comprising: the estimated temperature; and a failure diagnosis means for performing a failure diagnosis of the Stirling engine based on the measured temperature. In the Stirling engine failure diagnosis apparatus according to claim 1,
An apparatus for diagnosing a failure of a Stirling engine , wherein the temperature of the exhaust gas of the internal combustion engine before the recovery of the thermal energy is estimated based on the rotational speed and load torque of the internal combustion engine . The Stirling engine failure diagnosis apparatus according to claim 1 or 2,
The failure diagnosis means diagnoses that the Stirling engine has failed when an absolute value of a difference between the estimated temperature and the measured temperature exceeds a predetermined value. Engine failure diagnosis device. In the failure diagnosis apparatus for a Stirling engine according to any one of claims 1 to 3,
When the Stirling engine is diagnosed as having a failure, the Stirling engine failure diagnosis device is notified of the fact .

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