JP4306467B2 - Stirling engine and hybrid system - Google Patents

Description

  The present invention relates to a Stirling engine, and more particularly to a Stirling engine that can be easily miniaturized and hardly adversely affects the ease of assembly of other components.

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

  Japanese Patent Application Laid-Open No. 8-210715 (Patent Document 1) describes a technique related to a Stirling engine in which technical considerations regarding weight balance are made. According to this technique, the weight balance mechanism constituted by the balance weight is disposed on the crankshaft so as to face the locking points of the compression piston and the expansion piston.

  Japanese Patent Laid-Open No. 10-61492 (Patent Document 2) describes a technique in which a crankshaft and a balance weight are integrated. Patent Document 2 describes that, according to this technology, the connection between the crankshaft and the balance weight becomes unnecessary, the number of parts and the number of assembly steps are reduced, and the casting mold for the balance weight is also unnecessary. Has been.

JP-A-8-210715 Japanese Patent Laid-Open No. 10-61492 Japanese Patent Laid-Open No. 1-200049 Japanese Patent Laid-Open No. 10-318042

  By the way, there is a case where downsizing of the device scale (overall configuration) of the Stirling engine is required. In particular, when the Stirling engine is operated using exhaust heat such as exhaust gas from an internal combustion engine of a vehicle as a heat source, the space is limited, such as a space adjacent to an exhaust pipe of the internal combustion engine disposed under the floor of the vehicle. In some cases, it may be necessary to install a Stirling engine in the open space. In that case, the scale of the Stirling engine needs to be kept compact.

  If a balance weight is provided for a Stirling engine that is required to be compact, it will be difficult to achieve compactness and it will be difficult to assemble other parts if the arrangement is not devised. There's a problem.

  An object of the present invention is to provide a Stirling engine and a hybrid system having a balance weight that can easily reduce the size of the Stirling engine and hardly adversely affect the assembly of other components.

A Stirling engine of the present invention is an α-type two-cylinder Stirling engine, and includes a connecting portion between a crankshaft and a connecting rod of a high-temperature side power piston, and a connecting portion between the crankshaft and a connecting rod of a low-temperature side power piston. during in, and a single balance weight provided we are one only of the high-temperature side power piston side and the low-temperature side power piston side in the crankshaft, an output of the Stirling engine, the high-temperature side power piston The first piston in the first cylinder and the second piston in the second cylinder of the low temperature side power piston are taken out through a drive shaft connected in common, and the first piston is at top dead center The distance between the top of the first piston and the drive shaft is such that the second piston Is characterized in that it is configured to be larger than the distance between the top portion and the drive shaft of the second piston when in the dead center.

According to the present invention, the Stirling engine can be easily reduced in size, and adverse effects on the assembling properties of components to be assembled by inserting a crankshaft such as a bearing can be suppressed. Further, it is possible to suppress an adverse effect on the assemblability of components (bearings, connecting rods, etc.) through which the crankshaft is inserted during assembly. In addition, since a balance weight is provided between the connecting portion between the crankshaft and the connecting rod of the high temperature side power piston and the connecting portion between the crankshaft and the connecting rod of the low temperature side power piston, it rotates. When supporting the crankshaft, the weight imbalance is corrected near the support center, which is effective. Further, by utilizing the difference, the upper portion of the first cylinder is disposed in a region where heat can be received, for example, inside an exhaust pipe of a vehicle, and the cooler and the second cylinder are disposed outside the region where heat can be received. Easy to do.

  In the Stirling engine of the present invention, the high temperature side power piston and the low temperature side power piston are arranged in series, and include a heat exchanger having a cooler, a regenerator, and a heater, and the heat exchanger includes the high temperature side At least a part of the heat exchanger has a curved shape so as to connect the first cylinder of the side power piston and the second cylinder of the low temperature side power piston.

  According to the present invention, two cylinders are arranged in series, and at least a part of the heat exchanger is configured to have a curved shape so as to connect the first and second cylinders. The mounting space can be kept compact, and the degree of freedom of installation is increased even when mounted in a limited space such as a vehicle. Furthermore, for example, when a region where heat can be received, such as the inside of a pipe, is limited, if the heater is formed in a curved shape within the region, the heat transfer area can be as large as possible. Further, when the cooler or the regenerator has a curved shape, the channel resistance can be reduced as compared with a cornered shape. From the viewpoint of flow path resistance, a part of the heat exchanger is configured to have no corners. It is preferable that the axis of the flow path of the heat exchanger is not composed of a combination of straight lines but a combination of a curved line and a straight line or only a curved line so that a corner portion is not formed.

  In the Stirling engine of the present invention, the heater is configured to have the curved shape that connects the first cylinder and the second cylinder, and the cooler and the regenerator are provided in the second cylinder. It is characterized by being configured in a straight line along the extending direction.

  According to the present invention, if the curved portion of the heater is designed and arranged corresponding to a limited area that can receive heat, such as the inside of a tube, heat transfer is performed in that area. The area can be as large as possible. Further, since the cooler and the regenerator are configured in a straight line along the extending direction of the cylinder, the flow resistance is small.

  The Stirling engine of the present invention is characterized in that the balance weight is provided only on the high temperature side power piston side of the crankshaft.

  According to the present invention, since the weight supported by the connecting rod on the high temperature side power piston side is heavier than the weight supported by the connecting rod of the low temperature side power piston, the balance weight is the high temperature side power piston on the crankshaft. If it is provided only on the side, the unbalance weight can be corrected effectively. In addition, when the size of the Stirling engine is determined by the size of the low temperature side power piston, the balance weight is provided only on the high temperature side power piston side of the crankshaft. An arrangement space for the balance weight can be ensured while minimizing the influence on the balance weight.

  In the Stirling engine of the present invention, the difference in the distance is that the length of the first connecting shaft that connects the piston pin of the first piston and the first piston, and the piston pin of the second piston and the second piston are connected. It corresponds to the difference in the length of the second connecting shaft. According to the present invention, the above-described invention can be configured with a simple configuration.

  In the Stirling engine of the present invention, the difference in distance corresponds to a difference in length between the first piston and the second piston.

  According to the present invention, by forming the length of the first piston to be long, the top surface side of the first piston is arranged in the heat-receivable region, and the temperature gradient is in a direction away from the top surface side of the first piston. Can be kept large, and the space between the first cylinder and the first cylinder can be sealed at a position that is relatively low in temperature compared to the top surface side and is not affected by thermal expansion.

  In the Stirling engine of the present invention, the surface connected to the heater in the first cylinder and the surface connected to the heater in the regenerator are exhaust gas to which exhaust heat recovered by the Stirling engine is supplied. The surface of the first cylinder connected to the heater and the surface of the regenerator connected to the heater are substantially the same so as to be exposed in the passage.

  According to the present invention, a large step is not formed in the exhaust passage between the surface connected to the heater in the first cylinder and the surface connected to the heater in the regenerator. The flow resistance is suppressed against the flow of the fluid that becomes the heat source flowing through the exhaust passage.

  In the Stirling engine of the present invention, the piston is further directly or indirectly connected to at least one of the piston of the high temperature side power piston and the piston of the low temperature side power piston, and the connected piston reciprocates in the cylinder. In this case, an approximate linear mechanism is provided so as to perform an approximate linear motion.

  A hybrid system of the present invention is a hybrid system including the above-described Stirling engine of the present invention and an internal combustion engine of a vehicle, wherein the Stirling engine is mounted on the vehicle, and a heater of the Stirling engine is the internal combustion engine. It is provided to receive heat from the exhaust system.

  In the hybrid system of the present invention, the heat exchanger of the Stirling engine connects the upper parts of the cylinder of the high temperature side power piston and the cylinder of the low temperature side power piston, and the inner diameter dimension of the exhaust pipe of the internal combustion engine, The curve shape is set according to a configuration in which the distance between the end of the heater and the uppermost portion of the heater is approximately the same.

In the present invention, for example, the following configuration is adopted.
(1) A configuration in which a balance weight (counter weight) is provided only on either the high temperature side cylinder side or the low temperature side cylinder side in the exhaust heat recovery Stirling engine.
(2) In the above (1), the number of balance weights is only one.
(3) In the above (1) or (2), the balance weight is arranged on the cylinder side (high temperature side cylinder side) where the unbalance weight is large.

  The Stirling engine for exhaust heat recovery according to the present invention has a problem of making the engine size as compact as possible. In order to make it more compact, it is necessary to drive the engine height and width to the limits. Therefore, in the present invention, the counter weight on the low temperature side cylinder side is eliminated, and the total length is shortened to the limit where the piston does not interfere with the approximate linear link. Considering the ease of assembly of the bearing, only one counterweight is arranged on the high temperature side cylinder side which has a space and has a large unbalanced weight due to the structure of the heat exchanger.

  According to the Stirling engine of the present invention, downsizing is easy to achieve and it is difficult to adversely affect the assembling property of other parts.

  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. 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.

  The Stirling engine 10 of this embodiment is used with a gasoline engine (internal combustion engine) 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 a gasoline engine as a heat source. The heater 47 of the Stirling engine 10 is disposed inside the exhaust pipe 100 of the gasoline engine 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 connected to the upstream side (the side close to the gasoline engine) 100a of the exhaust gas through which a relatively high-temperature exhaust gas flows. The high temperature side cylinder 22 side 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 gasoline engine) 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 of the working fluid, the higher the pressure difference with respect to the same temperature difference caused by the cooler 45 and the heater 47, so that 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.

  The upper part of the regenerator 46 is disposed inside an exhaust pipe (exhaust duct) 100. Hereinafter, the reason why the upper part of the regenerator 46 is provided in the exhaust pipe 100 will be described.

  In this embodiment, 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 effectively within the range of the obtained heat amount. . Therefore, the top (upper part) 22b of the high temperature side cylinder 22 and the upper part of the side surface 22c of the high temperature side cylinder 22 are arranged inside the exhaust pipe 100 so that the working fluid as hot as possible flows in the expansion space. Thereby, the upper part of the expansion piston 21 in the vicinity of the top dead center is located inside the exhaust pipe 100, and the upper part of the expansion piston 21 is effectively heated.

  On the other hand, in the Stirling engine 10 in which the two cylinders 22 and 32 are arranged in series and parallel, the entire portion from the first end portion 47ta to the second end portion 47tb is disposed inside the exhaust pipe 100. The upper surface 46a of the regenerator 46 is connected to the second end 47tb opposite to the first end 47ta to which the high temperature side cylinder 22 is connected. The second end 47tb of the heater 47 and the upper surface 46a of the regenerator 46 are directly connected to each other without connecting pipes in order to suppress an increase in ineffective volume that is not directly related to the output of the Stirling engine 10. Connected. An upper surface 46a of the regenerator 46 is accommodated in the exhaust pipe 100 so as to be substantially at the same position as the top portion 22b of the high temperature side cylinder 22 in the vertical direction.

  Hereinafter, the reason why the upper surface 46a of the regenerator 46 is disposed in the exhaust pipe 100 so as to be substantially at the same position as the top portion 22b of the high temperature side cylinder 22 in the vertical direction will be described.

  The first reason is to suppress an increase in flow resistance of exhaust gas flowing through the exhaust pipe 100 and occurrence of stagnation. That is, in order to allow the exhaust gas to smoothly flow in a straight line along the extending direction of the exhaust pipe 100 (the left-right direction in the figure), the top surface 46a of the regenerator 46 and the top portion 22b of the high temperature side cylinder 22 In this way, no vertical step is formed.

  The second reason is to make the Stirling engine 10 compact. That is, since the Stirling engine 10 is mounted in a limited space adjacent to the exhaust pipe of the internal combustion engine disposed under the floor of the vehicle, the Stirling engine 10 is required to be downsized. Here, as an index of downsizing of the Stirling engine 10, from each of the first and second end portions 47 ta and 47 tb of the heater 47 accommodated in the exhaust pipe 100 to the crankshaft 61 (drive shaft 40). Consider the length dimension in the vertical direction.

  In this case, it is not the high temperature side power piston 20 side but the low temperature side power that determines the vertical length from the first and second end portions 47ta and 47tb of the heater 47 to the crankshaft 61. This is the length on the piston 30 side. The reason is that, in the vertical direction, the component on the high temperature side power piston 20 side is only the high temperature side cylinder 22, whereas the low temperature side power piston 30 side includes the cooler 45 and the regeneration in addition to the low temperature side cylinder 32. The length in the vertical direction is increased by the amount of the vessel 46.

  Here, in the present embodiment, the length in the vertical direction of the high temperature side cylinder 22 is formed larger than that of the low temperature side cylinder 32. As a result, the difference in the length in the vertical direction between the high temperature side power piston 20 side and the low temperature side power piston 30 side, which is caused by the difference in the number of components described above, is reduced.

  However, the length of the power piston 30 on the low temperature side is still longer. From this, the length of the Stirling engine 10 in the vertical direction is determined by the length of the low-temperature power piston 30 side.

  From the above, in this embodiment, the counterweight 90 affects 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. The counterweight 90 is provided on the high temperature side cylinder 22 side where a space can be secured without any problem. The arrangement and number of counterweights 90 will be described later.

  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 exhaust gas of the gasoline engine of the vehicle as described above, and is not a heat source prepared exclusively 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 arrangement and number of counterweights 90 will be described as described above.

  In the Stirling engine 10 of the present embodiment, a single counterweight 90 is a portion of the crankshaft 61 that is confiscated to the high temperature side power piston 20 side, and the high temperature side power piston 20 and the low temperature side power piston 30 It is provided in the vicinity of the space (central part). That is, the counterweight 90 is a portion of the crankshaft 61 that is confiscated to the high temperature side power piston 20 side, and the portion where the connecting rod 65a of the high temperature side power piston 20 is connected to the crankshaft 61, and the low temperature side power. Only one connecting rod 65 b of the piston 30 is disposed between the connecting rod 65 b and the portion connected to the crankshaft 61. The counterweight 90 is provided integrally with the crankshaft 61 as a single body, not as a separate member.

  As described above, in the present embodiment, there is a technical significance of changing the positions of the top dead centers of the compression piston 31 and the expansion piston 21, and in order to change the positions of the top dead centers, the piston pins 60a, 60b, The pistons 31 and 21 are connected by extension portions (piston strut portions) 64b and 64a having different lengths. 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. Alternatively, the length of the expansion piston 21 in the vertical direction can be made larger than the length of the compression piston 31 in the vertical direction, as described above, instead of the configuration in which the extension portions having different lengths are provided. . Regardless of which of these configurations is adopted, the weight supported by the connecting rod 65a of the high temperature side power piston 20 is heavier than the weight supported by the connecting rod 65b of the low temperature side power piston 30.

  Therefore, in the crankshaft 61, the side where the connecting rod 65a of the high temperature side power piston 20 is connected to the crankshaft 61 is compared with the side where the connecting rod 65b of the low temperature side power piston 30 is connected to the crankshaft 61. The unbalanced weight is large. From this, it is effective that the counterweight 90 is provided in a portion of the crankshaft 61 that is expropriated in the high temperature side power piston 20 (not in a portion accommodated in the low temperature side power piston 30).

  Further, when the counterweight 90 is provided on the crankshaft 61, the radial direction of the crankshaft 61 is increased (expanded) at the portion where the counterweight 90 is provided. Various members (including the pistons 21 and 31) around the crankshaft 61 need to be arranged so as not to interfere with the counterweight 90, which increases the vertical length of the Stirling engine 10. Easy to cause. As described above, the length in the vertical direction of the Stirling engine 10 of the present embodiment is determined by the length of the power piston 30 on the low temperature side. From this, it is the high temperature side power piston 20 side that can secure the arrangement space while minimizing the influence of the counterweight 90 on the vertical size of the entire Stirling engine 10. This is also one of the reasons why the counterweight 90 is provided on the high temperature side power piston 20 side.

  The crankshaft 61 is rotatably supported by the crankcase 41 by three bearings (bearings) 95 (95a to 95c). The end of the crankshaft 61 on the high temperature side power piston 20 side is supported by a bearing 95a, the end of the crankshaft 61 on the low temperature side power piston 30 side is supported by a bearing 95b, and the center portion of the crankshaft 61 is It is supported by a bearing 95c. The bearings 95a to 95c can be rolling bearings.

  Here, when supporting the rotating crankshaft 61, the support center is the bearing 95 c that supports the central portion of the crankshaft 61 in the longitudinal direction. For this reason, it is effective for the crankshaft 61 to correct the imbalance in weight in the vicinity of the bearing 95c. For this reason, the counterweight 90 is provided in the vicinity of the bearing 95c.

  Next, the counterweight 90 is provided on the crankshaft 61 only on one power piston side (high temperature side power piston 20 side), and both power piston sides (high temperature side power piston 20 side and low temperature side power piston 30). The reason why it is not provided on the side) will be described.

  The reason is that the assembling property of the bearing 95c is taken into consideration. As shown in FIG. 2, the bearings 95 a to 95 c are assembled so that the bearings 95 a to 95 c are inserted through the crankshaft 61 before the bottom surface portion 41 a of the crankcase 41 is attached. In this assembling operation, the bearings 95 a and 95 b assembled to the respective ends of the crankshaft 61 need not be moved in the longitudinal direction of the crankshaft 61 while being inserted into the crankshaft 61. Therefore, in assembling the bearings 95a and 95b, there is no problem even if the counterweight 90 is provided on both power pistons, and the counterweight 90 need not be provided only on one power piston side.

  On the other hand, in the bearing 95c, if counter weights are provided on both power pistons 20 and 30, the counter weight 90V1 is provided in addition to the counter weight 90 in the example of FIG. If this is the case, the bearing 95c cannot be inserted from the end of the crankshaft 61 and moved to the center of the crankshaft 61 (the assembly position of the bearing 95c) (from either the left or right end in the figure). Even if it is inserted, it will interfere with the counterweight 90 or 90V1). Therefore, in the present embodiment, the counter weight 90 is provided only on one power piston 20 side, and the bearing 95c is inserted from the end on the other power piston 30 side where the counter weight is not provided, so that the center portion of the crankshaft 61 is inserted. Can be moved to.

  In this case, as shown in FIG. 3, if a two-part (divided type, half-type) bearing 97 is used as the bearing 95 c, the bearing 97 c moves in the longitudinal direction of the crankshaft 61. There is no need, and the bearing 97 can be assembled at a predetermined position. Therefore, when the split bearing 97 is used, even if the counterweights 90 and 90V1 are provided on both power pistons 20 and 30, interference with the counterweights 90 and 90v1 becomes a problem. It is possible to assemble it in the center part of the crankshaft 61 without it. However, since the Stirling engine 10 of this embodiment operates using the exhaust gas of the vehicle as a heat source, the Stirling engine 10 is small and the diameter of the crankshaft 61 is small (for example, 10 mm). A split type bearing used for such a small-diameter crankshaft 61 is generally expensive, leading to an increase in cost. In the present embodiment, in order to increase the degree of freedom of selection of the bearing, the bearing 95c is not a split type but a general one. Therefore, the counterweight 90 is provided on the crankshaft 61 only on one power piston side (on the high temperature side power piston 20 side).

  Next, the reason why the counterweight 90 is single (only one) in the crankshaft 61 will be described.

  If a plurality of counterweights are provided on one power piston side (on the high temperature side power piston 20 side) as shown by reference numeral 90V2 in FIG. 2, the connecting rod of the high temperature side power piston 20 is connected to the crankshaft 61. In many cases, the workability of assembling the 65a is deteriorated. That is, when the connecting rod 65 a is assembled to the crankshaft 61, the connecting rod 65 a is inserted into the crankshaft 61 from the end of the crankshaft 61 on the high-temperature side power piston 20 side along the longitudinal direction of the crankshaft 61. However, the counterweight 90V2 interferes and cannot be moved along the longitudinal direction of the crankshaft 61. Therefore, when there is a counterweight 90V2, it is necessary to make the connecting portion of the connecting rod 65a connected to the crankshaft 61 a split type, which leads to an increase in cost. Therefore, it is not preferable that the plurality of counterweights 90 and 90V2 are provided in the crankshaft 61 at a position sandwiching the connecting portion of the connecting rod 65a, and the number of counterweights 90 should be single.

  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.

  Hereinafter, the approximate linear mechanism 50 of the grasshopper will be described.

A. Outline of piston / crank mechanism:
FIG. 4A is an explanatory view showing a piston / crank mechanism in a conventional Stirling engine, and FIG. 4B is an explanatory view showing a piston / crank mechanism in the Stirling engine 10 of the present embodiment. As shown in FIG. 4A, the conventional mechanism includes a cylinder 110, a piston 120, a connecting rod 130, and a crankshaft 140. The piston 120 and the connecting rod 130 are connected to each other by a piston pin 160 near the center of the piston 120. The connecting rod 130 and the crankshaft 140 are connected by a crank pin 162. When the piston 120 reciprocates up and down, the crankshaft 140 rotates about its axis 142 (also referred to as “drive shaft”).

  FIG. 4B 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.

  The piston / crank mechanism of the Stirling engine 10 includes a cylinder 32, a piston 31, a connecting rod 65, a crankshaft 61, and an approximate linear mechanism 50. The approximate linear mechanism 50 is an approximate linear mechanism of a grasshopper as described above.

  As shown in FIGS. 2 and 4-2, the piston column part 64 b is connected to the piston 31. The piston 31 and the piston support 64b are formed as separate bodies. The lower end portion of the piston 31 and the upper end portion of the piston support portion 64 are connected to each other by a pin 67 so as to be rotatable. The piston struts 64 are connected to each other by a piston pin 60 at the lower end of the piston struts 64. The connecting rod 65 and the crank shaft 61 are connected by a crank pin 62. When the piston 31 reciprocates up and down, the crankshaft 61 rotates around its axis 40 (also referred to as “drive shaft”).

  The approximate linear mechanism 50 has two lateral links 52 and 54 and one longitudinal link 56. One end of the first lateral link 52 is rotatably connected to the lower end of the piston support 64 at the position of the piston pin 60. One end of the second lateral link 54 is rotatably connected to the first lateral link 52 at a predetermined position in the middle of the first lateral link 52. The other end of the second lateral link 54 is rotatably fixed at a predetermined position of the piston / crank mechanism. One end of the longitudinal link 56 is rotatably connected to the first lateral link 52 at the end of the first lateral link 52 opposite to the piston pin 60. The other end of the longitudinal link 56 is rotatably fixed to a predetermined position of the piston / crank mechanism.

  In FIGS. 4A and 4B, a connecting portion (such as the drive shaft 40) represented by a black circle rotates or rotates about the axis, but does not change the relative position with the cylinder 32. (Hereinafter referred to as “fulcrum”). Further, a connecting portion (piston pin 60 or the like) represented by a white circle rotates or rotates around its axis and changes its relative position to the cylinder 32 (hereinafter referred to as “moving connecting point”). ). Here, “rotation” means turning in a range of 360 degrees or more, and “rotation” means turning in a range of less than 360 degrees.

  4A and 4B, the illustration of the Stirling engine 10 of the present embodiment other than the piston / crank mechanism and the cylinder 32 is omitted.

  (A)-(C) of FIG. 5 is explanatory drawing which shows the link structure of the piston crank mechanism of this embodiment. FIG. 5A shows only the cylinder 32, the piston 31, the connecting rod 65, and the crankshaft 61. FIG. 5B shows only the approximate linear mechanism 50. (C) in FIG. 5 is the same as the mechanism shown in FIG. 4-2, and is a combination of the configurations of (A) and (B) in FIG.

In (A) to (C) of FIG. 5, various connection points are represented as follows.
(1) Moving connection point A: central axis of the piston pin 60 (FIG. 4-2).
(2) Moving connection point B: A connection point at the end of the first lateral link 52 opposite to the moving connection point A.
(3) Moving connecting point C: A connecting point at the end of the connecting rod 65 opposite to the moving connecting point A.
(4) Moving connection point M: A connection point at the midpoint of the first lateral link 52.
(5) Support point P: the central axis (drive shaft) of the crankshaft 61.
(6) Support point Q: A connection point at the end of the second lateral link 54 opposite to the moving connection point M.
(7) Support point R: A connection point at the end of the vertical link 56 opposite to the moving connection point B.

  The moving connection point A is the central axis of the piston pin 60 and moves along the up-down direction Z ((B) of FIG. 5) as the piston 31 reciprocates. In the present specification, the vertical direction Z means a direction along the axial center line (also referred to as “axial center”) of the cylinder 32. The moving connection points A and B are connection points at both ends of the first lateral link 52. The moving connection point B moves on an arcuate locus as the vertical link 56 rotates about the fulcrum R. The moving connection point B is set so as to have substantially the same vertical position as the vertical position X of the fulcrum Q of the second lateral link 54.

  If the length of the vertical link 56 is virtually set to infinity, and the moving connection point B moves linearly on the same vertical position X as the fulcrum Q, the movement connection point A Performs a movement close to a perfect straight line in the vertical direction Z. Actually, since the length of the longitudinal link 56 is finite, the moving connection point A moves on a locus slightly deviated from the linear motion (this will be described later). An almost complete linear motion mechanism can be realized by adopting a guide portion that linearly guides the moving connection point B instead of the longitudinal link 56. However, the friction between the guide portion and the moving connection point B is reduced. Increase. Therefore, from the viewpoint of reducing friction, the approximate linear mechanism 50 of the present embodiment is preferable to a complete linear motion mechanism.

The position of the moving connection point M in the middle of the first lateral link 52 is set so as to satisfy the following relationship.
AM × QM = BM ²

  Here, AM means the distance between the connection points A and M, QM means the distance between the connection points Q and M, and BM means the distance between the connection points B and M, respectively.

  6A to 6D show changes in the shape of the piston / crank mechanism accompanying the movement of the piston 31. Of the three moving connection points A, B, and M of the approximate linear mechanism 50, the moving connection points A and M move considerably with the movement of the piston 31. I understand that does not move much. FIG. 6A shows two angles θ and φ that can be used as indices indicating the degree of change in the shape of the approximate linear mechanism 50. The first angle θ is an angle ∠ MQX of the second lateral link 54 measured from the lateral direction X. The second angle φ is the inclination angle of the vertical link 56 from the vertical direction Z and is ∠BRZ. The ranges that the values of these angles θ and φ take depend on the setting of the moving range of the moving connection point A (that is, the stroke of the piston 31) and the length of each link of the approximate linear mechanism 50.

  As described above, the lower end portion of the piston 31 and the upper end portion of the piston support 64 are connected to each other by the pin 67 so as to be rotatable. In this configuration, even when the locus of the lower end of the piston column 64 slightly deviates from the straight line, the displacement does not work as a force for tilting the piston 31 (that is, the displacement of the lower end of the piston column 64 is not applied to the piston 31). Has the advantage of having little effect). That is, in order to absorb the deviation from the linear motion that occurs during the reciprocating motion of the grasshopper mechanism 50, the piston 31 and the piston support 64 are connected not in a rigid manner but in a relatively movable state (free state). To do. In this embodiment, it connects using the pin 67 as an example. Moreover, compared with the case where a piston and a piston support | pillar part are integrally formed, there also exists an advantage that the operation | work which assembles a piston with an approximate linear mechanism and a connecting rod becomes easy. On the other hand, although not shown in the figure, when the piston column part 64 and the piston 31 are integrally formed, even if the piston 31 is inclined with respect to the cylinder 32 for some reason, the piston column part 64 is an approximate straight line. There is an advantage that the inclination is corrected when exercise is performed.

FIG. 7A is an explanatory diagram illustrating an example of specific dimensions of the piston / crank mechanism in the present embodiment, and FIG. 7B is an explanatory diagram illustrating a trajectory of the moving connection point A. It can be seen that the dimensions shown in FIG. 7-1 satisfy the relationship (AM × QM = BM ² ) described above. As shown in FIG. 7B, the trajectory of the moving connection point A includes an approximate straight line portion, and this approximate straight line portion is used as the stroke range of the piston 31. At this time, the stroke range of the piston 31 is set so that the amount of deviation from the straight line at the top dead center is smaller than the amount of deviation from the straight line at the bottom dead center. Here, the “straight line” of the “deviation amount from the straight line” means the axial center line of the cylinder 32. In the example of FIG. 7-2, the amount of deviation at the top dead center is about 5 μm, and the amount of deviation at the bottom dead center is about 20 μm. This numerical value is measured at room temperature.

  The reason why the amount of deviation from the straight line of the moving connection point A at the top dead center is set to be smaller than the amount of deviation at the bottom dead center is that the force by the compressed air is applied to the piston 31 near the top dead center. (Similarly, in the high temperature side power piston 20, the force by the expanded air is applied to the piston 21 in the vicinity of the top dead center). That is, if the displacement amount at the top dead center is small, the thrust (lateral force) applied to the piston 31 (or to the piston 21 by the force of the expanded air) due to the force of the compressed air becomes small. Alternatively, friction between the piston 21 and the cylinder 22) can be reduced. On the other hand, since the force due to the compressed air (or the force due to the expansion air) is not applied at the bottom dead center, the influence on the friction is small compared to the top dead center even if there is some deviation.

  The approximate straight line portion in the locus of the moving connection point A can be increased by increasing the length of each link 52, 54, 56. However, if the link is lengthened, the size of the approximate straight line mechanism 50 is increased. There is a problem of growing. In other words, the amount of deviation from the straight line at the top dead center or the bottom dead center and the size of the approximate linear mechanism 50 are in a trade-off relationship. Considering these points, it is preferable to configure the approximate linear mechanism 50 so that the deviation from the straight line of the moving connection point A at the top dead center of the piston 31 is about 10 μm or less when measured at room temperature. Further, it is preferable that the amount of deviation at the bottom dead center is about 20 μm or less.

  As shown in FIG. 7-2, when the range of the stroke of the piston 31 is set, the angle θ of the second lateral link 54 takes a value in the range of 8.8 ° to −17.9 °. (FIG. 7-1). The maximum value (8.8 °) of the angle θ corresponds to the case where the piston 31 is at the top dead center (FIG. 6-1), and the minimum value (−17.9 °) is at the bottom dead center. This corresponds to the case (FIG. 6-3). The angle φ of the longitudinal link 56 takes a value in the range of 0 ° to 2.2 °. The minimum value (0 °) of the angle φ corresponds to the case where the connection points Q, A, M, and B are arranged substantially in a straight line, and the maximum value (2.2 °) is the largest absolute value of the angle θ. Corresponds to the case (bottom dead center in this example). Note that the range of the values of these angles θ and φ depends on the dimensions of the links of the approximate linear mechanism 50 and the setting of the stroke range of the piston 31.

B. Specific shape examples:
8 and 9 show an example of a specific shape of the piston / crank mechanism in the present embodiment. As described above, the piston 31 is formed in a columnar shape. A piston ring groove and a piston ring are not provided on the outer peripheral surface of the piston 31. The plan view (transverse section) shape of the piston 31 is formed into a highly accurate perfect circle. The cylinder 32 is formed in a cylindrical shape, and the shape of the inner peripheral portion of the cylinder 32 in plan view is formed in a highly accurate perfect circle. As described above, the air bearing 48 is provided between the outer peripheral surface of the piston 31 and the inner peripheral portion of the cylinder 32. The air bearing 48 with good sealing performance is realized by forming the shape of each of the inner peripheral portions of the piston 31 and the cylinder 32 in a planar shape with high accuracy.

  A piston support 64 is provided between the piston pin 60 and the piston 31 in order to ensure a predetermined distance or more between the piston pin 60 and the piston 31. By opening a predetermined distance or more between the piston pin 60 and the piston 31 by the piston support 64, the piston 31 and the approximate linear mechanism 50 can be prevented from contacting when the piston 31 reciprocates.

  The length of the piston support 64 is set so that the length from the upper end of the piston 31 to the piston pin 60 is a value in a range of about 1/2 times or more and less than 1 time of the stroke of the piston 31. It is preferable. The reason is that if the length of the piston support 64 is excessively short, the approximate linear mechanism 50 may collide with the cylinder 32 or the piston 31 at the top dead center. Moreover, if the length of the piston support | pillar part 64 is too long, it is because the energy loss will increase by the part which the weight increases.

  As shown in FIG. 9, the piston strut 64, the connecting rod 65, and the first and second lateral links 52 and 54 are configured not to interfere with each other even when the piston 31 moves up and down. Yes. Specifically, in the example of FIG. 9, the piston strut portion 64 is provided in the center of the cylinder 32 in the axial direction, and both sides of the piston strut portion 64 are sandwiched between two plate-like members of the connecting rod 65. ing. Two plate-like members of the first lateral link 52 are arranged outside the connecting rod 65. These three types of members 64, 65, 52 are connected by a piston pin 60. Further, two plate-like members of the second lateral link 54 are installed on the outer side of the first lateral link 52. In other words, in this example, the connecting rod 65 and the two lateral links 52 and 54 each have a bifurcated structure in which the end portion is divided into two plate-like members, and the central piston column 64 is provided from both sides. It is arranged at each position to sandwich.

  10 is a longitudinal sectional view of a main part at a position where the crank is rotated from FIG. 8 and the horizontal links 52 and 54 are horizontal, and FIG. 11 is a sectional view taken along the line CC in FIG. In FIG. 11, for convenience of illustration, the connecting rod 65 and the piston support 64 are hatched.

  10 is a longitudinal sectional view of a main part at a position where the crank is rotated from FIG. 8 and the horizontal links 52 and 54 are horizontal, and FIG. 11 is a sectional view taken along the line CC in FIG. In FIG. 11, for convenience of illustration, the connecting rod 65 and the piston support 64 are hatched.

  In the configuration of FIG. 11, the end of the second lateral link 54 has a bifurcated structure and is disposed outside the other members 64, 65, 52, 60. When the approximate linear mechanism operates, the end portion of the first lateral link 52 passes between the bifurcated structures between the bifurcated structures of the second lateral link 54. According to such a configuration, even if the connecting rod 65 is shortened, the end of the first lateral link 52 and the end of the second lateral link 54 do not interfere with each other. An increase in the vertical dimension of the mechanism can be suppressed.

  Further, in the configuration shown in FIG. 11, the end of the first lateral link, the lower end of the piston support 64 (the lower end of the piston), and the upper end of the connecting rod 65 are connected by a single piston pin 60. Yes. According to such a configuration, the first lateral link 52, the piston strut portion 64, and the connecting rod 65 are connected by the single piston pin 60. Therefore, the structure of this connecting portion is simplified and can be made compact. There is an advantage.

  Further, in the configuration shown in FIG. 11, two of the three end portions of the end portion of the first lateral link 52, the lower end of the piston column portion 64, and the upper end of the connecting rod 65 are bifurcated. The remaining one end is arranged in the center of the two-end bifurcated structure. According to such a configuration, the connecting portion of the first lateral link 52, the piston strut portion 64, and the connecting rod 65 has a symmetric shape, so that side forces due to the asymmetric shape are generated. There is an advantage that it can be prevented.

  As described above, in the above-described embodiments and modifications, the piston / crank mechanism is provided with the approximate linear mechanism 50 so that the lower end of the piston 31 moves along the approximate linear trajectory along the axial center of the cylinder 32. As a result, the linear motion accuracy of the piston 31 is high, the side force of the piston 31 can be made substantially zero, and the air bearing 48 having a low pressure resistance in the thrust direction between the piston 31 and the cylinder 32. Even if it is provided, no problem occurs.

  The approximate linear mechanism of the grasshopper is particularly suitable for restricting the movement of the piston of the Stirling engine 10 because the point (moving connection point A) moving on the approximate straight line is biased near one end of the mechanism. Moreover, it is possible to obtain good linearity with a compact mechanism.

  In the embodiment described above, the configuration in which the Stirling engine 10 is attached to the exhaust pipe 100 to use the exhaust gas of the internal combustion engine of the vehicle as a heat source has been described. However, the Stirling engine of the present invention is not limited to a type attached to the exhaust pipe of an internal combustion engine of a vehicle.

1 is a front (cut) view showing a first embodiment of a Stirling engine of the present invention. It is a figure for demonstrating the assembly | attachment property of the counterweight in the exhaust heat recovery apparatus of 1st Embodiment of the Stirling engine of this invention. It is a perspective view which shows a split type bearing typically. It is explanatory drawing which shows the conventional piston crank mechanism. It is explanatory drawing which shows the piston crank mechanism applied in 1st Embodiment of the Stirling engine of this invention. In 1st Embodiment of the Stirling engine of this invention, it is explanatory drawing which shows the link structure of a piston crank mechanism. In 1st Embodiment of the Stirling engine of this invention, it is explanatory drawing which shows the shape change of the piston crank mechanism accompanying the movement of a piston. In 1st Embodiment of the Stirling engine of this invention, it is another explanatory drawing which shows the shape change of the piston crank mechanism accompanying the movement of a piston. In 1st Embodiment of the Stirling engine of this invention, it is other explanatory drawing which shows the shape change of the piston crank mechanism accompanying the movement of a piston. In 1st Embodiment of the Stirling engine of this invention, it is other explanatory drawing which shows the shape change of the piston crank mechanism accompanying the movement of a piston. In 1st Embodiment of the Stirling engine of this invention, it is explanatory drawing which shows an example of the specific dimension of a piston crank mechanism. It is explanatory drawing which shows the locus | trajectory of the movement connection point A. FIG. In 1st Embodiment of the Stirling engine of this invention, it is a principal part longitudinal cross-sectional view which shows an example of the specific shape of a piston crank mechanism. It is a principal part cross-sectional view of the piston crank mechanism in the state of FIG. FIG. 9 is a longitudinal sectional view of a main part of a piston / crank mechanism at a position where a crank rotates from the state of FIG. 8. It is a principal part cross-sectional view of the piston crank mechanism in the state of FIG.

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 41 Crankcase 41a Bottom surface part 45 Cooler 45a Upper surface of cooler 46 regenerator 46a upper surface of regenerator 46b lower surface of regenerator 47 heater 47ta first end portion 47tb second end portion 50 approximate linear mechanism 61 crankshaft 64a, 64b extension portions 65a, 65b connecting rod 90 counterweight (balance weight)
95a, 95b, 95c Bearing 100 Exhaust pipe

Claims (10)

an α-type 2-cylinder Stirling engine,
A connecting portion between the crankshaft and the high-temperature side power piston connecting rod, the crank shaft and between the connecting portion of the connecting rod of the low-temperature side power piston, and the high-temperature side power piston side and the low temperature in the crankshaft either the side power piston side only a single balance weight provided et al is in,
The output of the Stirling engine is taken out via a drive shaft commonly connected to a first piston in the first cylinder of the high temperature side power piston and a second piston in the second cylinder of the low temperature side power piston. ,
The distance between the top of the first piston and the drive shaft when the first piston is at top dead center is the distance between the top of the second piston and the drive when the second piston is at top dead center. A Stirling engine configured to be larger than the distance between the shafts . The Stirling engine according to claim 1,
The high temperature side power piston and the low temperature side power piston are arranged in series,
A heat exchanger having a cooler, a regenerator, and a heater,
The heat exchanger is configured such that at least a part of the heat exchanger has a curved shape so as to connect the first cylinder of the high temperature side power piston and the second cylinder of the low temperature side power piston. Stirling engine characterized by The Stirling engine according to claim 2 ,
The heater is configured to have the curved shape that connects the first cylinder and the second cylinder, and the cooler and the regenerator are linear along the extending direction of the second cylinder. A Stirling engine characterized by being configured in The Stirling engine according to any one of claims 1 to 3,
The balance weight is provided only on the high temperature side power piston side of the crankshaft . The Stirling engine according to any one of claims 1 to 4 ,
The difference in distance is that the length of the first connecting shaft that connects the piston pin of the first piston and the first piston, and the length of the second connecting shaft that connects the piston pin of the second piston and the second piston. A Stirling engine characterized by the difference in height. The Stirling engine according to any one of claims 1 to 4 ,
The difference in the distance corresponds to the difference in the length of the first piston and the length of the second piston . The Stirling engine according to any one of claims 2 to 6 ,
A surface connected to the heater in the first cylinder and a surface connected to the heater in the regenerator are provided so as to be exposed to an exhaust passage to which exhaust heat recovered by the Stirling engine is supplied. And
A Stirling engine characterized in that a surface connected to the heater in the first cylinder and a surface connected to the heater in the regenerator are substantially the same. The Stirling engine according to any one of claims 1 to 7 ,
Furthermore,
It is connected directly or indirectly to at least one of the piston of the high temperature side power piston and the piston of the low temperature side power piston so that the connected piston reciprocates in the cylinder so as to perform an approximate linear motion. A Stirling engine comprising an approximate linear mechanism provided. And Stirling engine according to any one of claims 1 to 8,
A hybrid system comprising an internal combustion engine of a vehicle,
The Stirling engine is mounted on the vehicle,
A hybrid system, wherein a heater of the Stirling engine is provided to receive heat from an exhaust system of the internal combustion engine . The hybrid system according to claim 9 , wherein
The heat exchanger of the Stirling engine connects the upper portions of the cylinder of the high temperature side power piston and the cylinder of the low temperature side power piston, and the inner diameter dimension of the exhaust pipe of the internal combustion engine, and the end of the heater The hybrid system , wherein the curve shape is set in accordance with a configuration in which the distance of the uppermost portion of the heater is approximately the same .

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