Reciprocating internal combustion engine

Abstract

To provide a reciprocating internal combustion engine capable of securing bearing strength and rigidity of a linear motion conversion mechanism which converts linear motion of a piston into rotational motion and realizing stable operation.SOLUTION: A reciprocating internal combustion engine comprises a planetary gear mechanism 1 provided with a ring gear RG, a carrier CR and a planetary gear PG, a crank member 2, and a piston member 8. In an axial direction L, a pair of planetary bearings B1 is arranged on both sides of the planetary gear PG and a pair of carrier bearings B2 is arranged on both sides of the ring gear RG. The crank member 2 has a first crank section 21 and a second crank section 22 arranged on both sides of the carrier CR. The piston member 8 has a first connection section 85 and a second connection section 86 which are connected to a piston body 82 and arranged on both sides of the carrier CR. The first connection section 85 and the first crank section 21 are connected to each other so as to be relatively rotational. The second connection section 86 and the second crank section 22 are connected to each other so as to be relatively rotational.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reciprocating internal combustion engine.

Background Art

[0002] Japanese Patent Application Laid-Open No. 9-119301 discloses a crank device (1) that converts the reciprocating motion of a piston (15) into the rotational motion of an output member (10) as a power conversion device applicable to a reciprocating internal combustion engine (in the background art, the reference numerals in parentheses are those of the cited document). The planetary gear mechanism (4) includes a ring gear (20) which is a fixed internal gear, a planetary gear (21) that meshes with the ring gear (20), and a crank arm (11) that functions as a carrier for rotatably supporting the planetary gear (21).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described crank device (1), as shown in FIG. 3 of the cited document, the planetary gear (21) is supported cantilevered by the crank arm (11), and the crank arm (11) is also supported cantilevered by the main shaft (10) of the crankshaft. Therefore, it is difficult to ensure the overall support strength and rigidity of the crank device (1) against the force transmitted from the piston (15).

[0005] In view of the above background, it is desired to provide a reciprocating internal combustion engine that can ensure the support strength and rigidity in a linear motion conversion mechanism for converting the linear motion of a piston into a rotational motion and can achieve stable operation.

Means for Solving the Problems

[0006] In view of the above, the reciprocating internal combustion engine includes a planetary gear mechanism including an internal gear ring gear, a carrier rotatably supported with respect to the ring gear, and a planetary gear rotatably supported with respect to the carrier and meshing with the ring gear; a crank member connected to rotate integrally with the planetary gear, with the direction along the carrier axis, which is the rotation axis of the carrier, being defined as the axial direction, the direction orthogonal to the carrier axis being defined as the radial direction, and the direction orthogonal to the planetary axis, which is the rotation axis of the planetary gear, being defined as the planetary radial direction; a piston member connected to be relatively rotatable about an input axis set at a position spaced from the planetary axis in the planetary radial direction with respect to the crank member; and a transmission mechanism for transmitting the rotation of the carrier to an output member. The radius of the ring gear is twice the radius of the planetary gear. A pair of planetary bearings for rotatably supporting the planetary gear with respect to the carrier are arranged on both sides of the planetary gear in the axial direction. A pair of carrier bearings for rotatably supporting the carrier with respect to the ring gear are arranged on both sides of the ring gear in the axial direction. The crank member includes a first crank part and a second crank part, which are a pair of crank parts arranged on both sides of the carrier in the axial direction. The piston member includes a piston body and a first connecting part and a second connecting part, which are a pair of connecting parts connected to the piston body and arranged on both sides of the carrier in the axial direction. The first crank part and the second crank part are arranged to extend in the planetary radial direction. The first connecting part is connected to the first crank part to be relatively rotatable about the input axis. The second connecting part is connected to the second crank part to be relatively rotatable about the input axis.

[0007] According to this configuration, the reciprocating motion of the piston member can be converted into rotational motion of the output member and output. Further, according to this configuration, the planetary gears are rotatably supported with respect to the carrier on both axial sides, and the carrier is rotatably supported with respect to the ring gear on both axial sides. Therefore, even when an axially-biased load acts on the planetary gears via the crank member, the load can be appropriately supported. For this reason, it is easier to extend the service life of the planetary gear mechanism and the transmission mechanism compared to the case where the planetary gears are cantilever-supported. Furthermore, according to this configuration, the pair of connecting portions and the pair of crank portions of the piston member are arranged separately on both axial sides with respect to the carrier, and each is connected so as to be relatively rotatable around the input axis center. Therefore, it is easy to ensure the rigidity of the support structure of the piston member, and it is easy to stabilize the operations of the piston member and the crank member. Thus, according to this configuration, it is possible to provide a reciprocating internal combustion engine that can ensure the rigidity of the linear motion conversion mechanism that converts the linear motion of the piston into rotational motion and can achieve stable operation.

[0008] Further features and advantages of the reciprocating internal combustion engine will become apparent from the following description of exemplary and non-limiting embodiments with reference to the drawings.

Brief Description of the Drawings

[0009]

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Figure 17

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the reciprocating internal combustion engine will be described with reference to the drawings. FIG. 1 is an axial sectional view schematically showing a first example of the reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 includes a planetary gear mechanism 1, a crank member 2, a piston member 8, a power conversion mechanism (corresponding to the "reciprocating unit 5" in the second and third examples (see FIGS. 2 to 5)), and a transmission mechanism 9.

[0011] As will be described in detail later, the planetary gear mechanism 1 includes a ring gear RG that is an internal gear, a carrier CR that is rotatably supported with respect to the ring gear RG, and a planetary gear PG that is rotatably supported with respect to the carrier CR and meshes with the ring gear RG. The crank member 2 is connected to the planetary gear PG so as to rotate integrally with the planetary gear PG. The piston member 8 is connected to the crank member 2 so as to be relatively rotatable about an input axis X3 that is set at a position separated from the planetary axis X2, which is the rotation axis of the planetary gear PG, in the planetary radial direction Rp that is orthogonal to the planetary axis X2, with respect to the crank member 2. The transmission mechanism 9 transmits the rotation of the carrier CR, which is the output rotation element of the planetary gear mechanism 1, to the output member 4. The rotation axis of the carrier CR is the carrier axis X1.

[0012] As described above, the planetary gear mechanism 1 includes a ring gear RG, a planetary gear PG, and a carrier CR. The ring gear RG is an internal gear and is fixed non-rotatably to, for example, the cylinder 81. The ring gear RG may be fixed to another non-rotating member such as a case in which the cylinder 81 is housed. The planetary gear PG is rotatably supported by the carrier CR and meshes with the ring gear RG. The radius of the ring gear RG (ring radius r1) is twice the radius of the planetary gear PG (planetary radius r2). Both the ring radius r1 and the planetary radius r2 are the radii of the pitch circles of the gears.

[0013] In the following description, the direction along the carrier axis X1 is defined as the axial direction L, and the direction orthogonal to the carrier axis X1 is defined as the radial direction R. Also, as described above, the direction orthogonal to the planetary axis X2 is defined as the planetary radial direction Rp. The carrier axis X1 and the planetary axis X2 are parallel, and the plane along the radial direction R and the plane along the planetary radial direction Rp are also parallel. Also, one side in the axial direction L is referred to as the first axial side L1, and the opposite side is referred to as the second axial side L2.

[0014] As shown in FIG. 1, the planetary gear mechanism 1 includes a planetary bearing B1 and a carrier bearing B2. The planetary bearing B1 is divided on both sides in the axial direction L with respect to the planetary gear PG, and a pair of the planetary bearings B1 are arranged to rotatably support the planetary gear PG with respect to the carrier CR. When distinguishing between the pair of planetary bearings B1, the bearing arranged on the first side L1 in the axial direction with respect to the planetary gear PG is referred to as the first planetary bearing B11, and the bearing arranged on the second side L2 in the axial direction is referred to as the second planetary bearing B12. The planetary bearing B1 is a relatively thin bearing such as a needle bearing or a sliding bearing, and has a small dimension in the planetary radial direction Rp. In addition, in the present embodiment, the planetary gear PG and the rotation shaft of the planetary gear PG are integrally formed, and the rotation shaft is rotatably supported by the planetary bearing B1. Here, "integrally formed" may be formed by the same member, or may be integrally formed by fixing separate members.

[0015] The carrier bearing B2 is divided on both sides in the axial direction L with respect to the ring gear RG, and a pair of the carrier bearings B2 are arranged to rotatably support the carrier CR with respect to the ring gear RG. When distinguishing between the pair of carrier bearings B2, the bearing arranged on the first side L1 in the axial direction with respect to the ring gear RG is referred to as the first carrier bearing B21, and the bearing arranged on the second side L2 in the axial direction is referred to as the second carrier bearing B22. The carrier bearing B2 is, for example, a ball bearing.

[0016] The first carrier bearing B21 is arranged so as to overlap the movement locus of the first planetary bearing B11 accompanying the revolution of the planetary gear PG in a radial view along the radial direction R. Similarly, the second carrier bearing B22 is arranged so as to overlap the movement locus of the second planetary bearing B12 accompanying the revolution of the planetary gear PG in a radial view along the radial direction R. In addition, regarding the arrangement of the two elements, "overlapping in a specific direction view" means that when a virtual straight line parallel to the line-of-sight direction is moved in each direction orthogonal to the virtual straight line, there is at least a part of a region where the virtual straight line intersects both of the two elements.

[0017] In other words, the first planetary bearing B11 and the first carrier bearing B21 overlap in the radial direction view, and the second planetary bearing B12 and the second carrier bearing B22 overlap in the radial direction view. This makes it easier to reduce the size of the axial dimension L of the reciprocating internal combustion engine 10. Also in this case, the entire one bearing is not limited to overlapping with the other bearing, and a part of each may overlap with each other.

[0018] The crank member 2 includes a pair of crank portions that are separated and arranged on both sides in the axial direction L with respect to the carrier CR. Specifically, the crank member 2 includes a first crank portion 21 arranged on the first axial side L1 with respect to the carrier CR and a second crank portion 22 arranged on the second axial side L2. And the first crank portion 21 and the second crank portion 22 are arranged to extend in the planetary radial direction Rp. As shown in FIG. 1, the crank member 2 extends across the planetary axis X2 and the input axis X3 spaced apart from the planetary axis X2 in the planetary radial direction Rp. The crank member 2 is connected to the planetary gear PG so as to rotate integrally with the planetary gear PG.

[0019] The piston member 8 includes a piston body 82 and a pair of connecting portions (connecting rods 83) that are connected to the piston body 82 and are separated and arranged on both sides in the axial direction L with respect to the carrier CR. Specifically, the pair of connecting rods 83 includes a first connecting portion 85 arranged on the first axial side L1 with respect to the carrier CR and a second connecting portion 86 arranged on the second axial side L2.

[0020] The crank member 2 and the piston member 8 are connected such that the first crank portion 21 and the first connecting portion 85 are connected to be relatively rotatable about the input axis X3, and the second crank portion 22 and the second connecting portion 86 are connected to be relatively rotatable about the input axis X3. Crank bearings B4 are respectively disposed between the first crank portion 21 and the first connecting portion 85, and between the second crank portion 22 and the second connecting portion 86, and are connected to be relatively rotatable via the crank bearings B4. The crank bearing B4 is a relatively thin rotary support member such as a needle bearing, a sliding bearing, a metal bush, etc., and has a small dimension in the radial direction R (the planetary radial direction Rp).

[0021] In addition, as illustrated in FIG. 1, in the present embodiment, an axial input member disposed on the input axis X3 is provided integrally with the crank member 2, and a configuration in which the input member and the connecting rod 83 are connected to be relatively rotatable is illustrated, but the present invention is not limited to this configuration. For example, an axial input member may be provided integrally with the connecting rod 83 on the input axis X3, and the input member and the crank member 2 may be connected to be relatively rotatable. Further, a form in which the input member is provided separately from the crank member 2 and the connecting rod 83 is not precluded. Further, a form in which the input member is not an axial member and the input axis X3 is a virtual axis is not precluded.

[0022] When the driving force from the piston member 8 is input to the input member on the input axis X3, the input member performs a reciprocating motion with reference to the carrier axis X1, and along with this reciprocating motion, the carrier CR rotates about the carrier axis X1.

[0023] In this embodiment, the radius of the planetary gear PG (planetary radius r2) and the distance in the planetary radial direction Rp between the planetary axis X2 and the input axis X3 (axial distance d23) are the same. For this reason, the movement locus in the reciprocating motion of the input member (input axis X3) is linear along the axial direction L in the axial view and passes through the carrier axis X1. In the following description, the direction along the linear movement locus in the reciprocating motion of the input axis X3 is referred to as the "reciprocating direction I". Further, the first connecting portion 85 and the second connecting portion 86 are integrally connected to the piston body 82. In this embodiment, an example is shown in which the piston body 82 and the connecting portion (connecting rod 83) are integrally formed by the same member. However, the piston body 82 and the connecting rod 83 may be constituted by separate members and integrated by bolting or welding.

[0024] The crank member 2 shown by the solid line in FIG. 1 shows a state where the piston body 82 is located at the top dead center of the reciprocating motion, and the crank member 2 partially shown by the phantom line shows a state where the piston body 82 is located at the bottom dead center of the reciprocating motion. In this embodiment, in the state where the piston body 82 is located at the bottom dead center of the reciprocating motion, the ring gear RG and the carrier CR are sandwiched between the first connecting portion 85 and the second connecting portion 86 in the axial direction L and are arranged so as to overlap the first connecting portion 85 and the second connecting portion 86 in the axial view.

[0025] Note that there is no hindrance to the axial distance d23 in the planetary radial direction Rp between the planetary axis X2 and the input axis X3 being different from the planetary radius r2. When the axial distance d23 and the planetary radius r2 are different, the movement locus of the input axis X3 becomes an elliptical orbit. In this case, the first connecting portion 85 and the second connecting portion 86 are swingably connected to the piston body 82.

[0026] The output member 4 is drivingly connected to the carrier CR via the transmission mechanism 9. In the present embodiment, as shown in FIG. 1, the transmission mechanism 9 includes a transmission gear 91 that rotates integrally with the carrier CR, and an output gear 92 that meshes with the transmission gear 91 and rotates integrally with the output member 4. The output gear 92 and the output member 4 are rotatably supported about an output axis X4 parallel to the carrier axis X1. In the present embodiment, the output member 4 is rotatably supported with respect to the case 6 connected to the cylinder 81 via a pair of output bearings B3. The output bearings B3 are, for example, ball bearings. Further, the transmission gear 91 and the output gear 92 are disposed between the axial directions L of a pair of carrier bearings B2.

[0027] Here, although the form in which the output member 4 is a shaft-like member is illustrated, the present invention is not limited to this form. Further, the transmission mechanism 9 is not limited to the form of a gear mechanism such as the transmission gear 91 and the output gear 92 illustrated. For example, when the carrier CR is connected to the rotor of a rotating electric machine that functions as a generator, the rotor of the rotating electric machine may be the output member 4. Further, the configuration in which the transmission gear 91 or the output gear 92 becomes the output member 4 does not interfere with the present invention.

[0028] In the present embodiment, the rotating members in the power transmission path from the piston member 8 to the output member 4 are supported symmetrically when viewed from a direction orthogonal to the axial direction L, as shown in FIG. 1. For this reason, it is easier to extend the service life of the planetary gear mechanism 1 and the transmission mechanism 9 compared to the case where the planetary gear PG or the like is cantilever-supported. Further, in the present embodiment, the pair of connecting rods 83 of the piston member 8 and the pair of crank portions (first crank portion 21, second crank portion 22) are separated and disposed on both sides of the carrier CR in the axial direction L, and each is relatively rotatably connected about the input axis X3. Therefore, it is easy to ensure the rigidity of the support structure of the piston member 8, and it is easy to stabilize the operations of the piston member 8 and the crank member 2.

[0029] Figures 2 and 3 show a second example of the reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 of the second example illustrates a so-called two-cylinder internal combustion engine, and includes two sets of power conversion mechanisms each including a planetary gear mechanism 1, a crank member 2, and a piston member 8, and a transmission mechanism 9. Here, the set of the planetary gear mechanism 1, the crank member 2, and the piston member 8 is referred to as a reciprocating unit 5. The reciprocating internal combustion engine 10 of the second example is configured to include a pair of reciprocating units 5. And each reciprocating unit 5 is drivingly connected to a common output member 4 via a transmission mechanism 9. Since the configuration of the reciprocating unit 5 is the same as that of the first example, a detailed description thereof will be omitted.

[0030] When distinguishing between the two reciprocating units 5, as shown in FIGS. 2 and 3, they are respectively referred to as a first reciprocating unit 5A and a second reciprocating unit 5B. Also, as shown in FIG. 3, the carrier axis X1 of the first reciprocating unit 5A is referred to as a first carrier axis X11, the carrier axis X1 of the second reciprocating unit 5B is referred to as a second carrier axis X12, the planetary axis X2 of the first reciprocating unit 5A is referred to as a first planetary axis X21, the planetary axis X2 of the second reciprocating unit 5B is referred to as a second planetary axis X22, the input axis X3 of the first reciprocating unit 5A is referred to as a first input axis X31, and the input axis X3 of the second reciprocating unit 5B is referred to as a second input axis X32. Also, the carrier CR of the first reciprocating unit 5A is referred to as a first carrier CR1, and the carrier CR of the second reciprocating unit 5B is referred to as a second carrier CR2. Also, as shown in FIGS. 2 and 3, in the second example, the transmission mechanism 9 includes a pair of transmission gears (a first transmission gear 91a and a second transmission gear 91b) and one output gear 92.

[0031] The first transmission gear 91a, which is one of the pair of transmission gears 91, rotates integrally with the carrier CR (the first carrier CR1) of the first reciprocating unit 5A, which is one of the pair of reciprocating units 5. The second transmission gear 91b, which is the other of the pair of transmission gears 91, rotates integrally with the carrier CR (the second carrier CR2) of the second reciprocating unit 5B, which is the other of the pair of reciprocating units 5. The output gear 92 meshes with both the first transmission gear 91a and the second transmission gear 91b.

[0032] In the present embodiment, as shown in FIG. 2, in the axial direction view, the output axis X4 is arranged at a position different from the line (virtual line "B") connecting the carrier axes X1 of the pair of reciprocating units 5. That is, the output axis X4 is arranged at a position deviated from the virtual line "B" connecting the first carrier axis X11 and the second carrier axis X12.

[0033] As shown in FIGS. 2 and 3, in the present embodiment, an example is given of a form in which the piston member 8 of the first reciprocating unit 5A and the piston member 8 of the second reciprocating unit 5B are arranged opposite to each other, that is, a form in which the reciprocating direction I of the piston member 8 of the first reciprocating unit 5A and the reciprocating direction I of the piston member 8 of the second reciprocating unit 5B are on the same straight line. However, the positional relationship between the first reciprocating unit 5A and the second reciprocating unit 5B is not limited to this form. For example, the reciprocating direction I of the piston member 8 of the first reciprocating unit 5A and the reciprocating direction I of the piston member 8 of the second reciprocating unit 5B may be parallel, and the first reciprocating unit 5A and the second reciprocating unit 5B may be arranged in parallel. Also, for example, the reciprocating direction I of the piston member 8 of the first reciprocating unit 5A and the reciprocating direction I of the piston member 8 of the second reciprocating unit 5B may intersect, and the first reciprocating unit 5A and the second reciprocating unit 5B may be arranged in a so-called V shape.

[0034] Further, the transmission mechanism 9 is not limited to a configuration in which both the first transmission gear 91a that rotates integrally with the first carrier CR1 and the second transmission gear 91b that rotates integrally with the second carrier CR2 mesh with the output gear 92. The transmission mechanism 9 may be configured such that the first transmission gear 91a and the second transmission gear 91b mesh with each other, and the output gear 92 meshes with either the first transmission gear 91a or the second transmission gear 91b.

[0035] Also, here, a form including two reciprocating units 5 is exemplified, but a form including three or more reciprocating units 5 may be provided.

[0036] Figures 4 and 5 show a third example of the reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 of the third example illustrates a so-called four-cylinder internal combustion engine, and includes four sets of a power conversion mechanism (reciprocating unit 5) including a planetary gear mechanism 1, a crank member 2, and a piston member 8, and a transmission mechanism 9. Also in the third example, a set of the planetary gear mechanism 1, the crank member 2, and the piston member 8 is referred to as the reciprocating unit 5. Since the configuration of the reciprocating unit 5 is the same as that of the first example, a detailed description thereof will be omitted.

[0037] When distinguishing the four reciprocating units 5, as shown in FIG. 5, they are respectively referred to as the first reciprocating unit 5A, the second reciprocating unit 5B, the third reciprocating unit 5C, and the fourth reciprocating unit 5D. Also, the carrier axes X1 of the first reciprocating unit 5A to the fourth reciprocating unit 5D are respectively referred to as the first carrier axis X11, the second carrier axis X12, the third carrier axis X13, and the fourth carrier axis X14, and the planetary axes X2 of the first reciprocating unit 5A to the fourth reciprocating unit 5D are respectively referred to as the first planetary axis X21, the second planetary axis X22, the third planetary axis X23, and the fourth planetary axis X24, and the input axes X3 of the first reciprocating unit 5A to the fourth reciprocating unit 5D are respectively referred to as the first input axis X31, the second input axis X32, the third input axis X33, and the fourth input axis X34. Also, the carriers CR of the first reciprocating unit 5A to the fourth reciprocating unit 5D are respectively referred to as the first carrier CR1, the second carrier CR2, the third carrier CR3, and the fourth carrier CR4. In the third example, the transmission mechanism 9 includes four transmission gears (the first transmission gear 91a, the second transmission gear 91b, the third transmission gear 91c, the fourth transmission gear 91d) and two output gears 92 (the first output gear 92a, the second output gear 92b).

[0038] As shown in Fig. 5, the first reciprocating unit 5A and the second reciprocating unit 5B are arranged side by side in the axial direction L. Also, the third reciprocating unit 5C and the fourth reciprocating unit 5D are arranged side by side in the axial direction L. That is, the first reciprocating unit 5A and the second reciprocating unit 5B are a pair of reciprocating units 5 arranged side by side in the axial direction L, and the third reciprocating unit 5C and the fourth reciprocating unit 5D are also a pair of reciprocating units 5 arranged side by side in the axial direction L. It can be said that the reciprocating internal combustion engine 10 of the third example includes two pairs of reciprocating units 5 arranged side by side in the axial direction L.

[0039] Focusing on each pair of reciprocating units 5 arranged side by side in the axial direction L, the transmission mechanism 9 is configured to include a pair of transmission gears 91 and a pair of output gears 92. In the pair of the first reciprocating unit 5A and the second reciprocating unit 5B, one of the pair of transmission gears 91 is the first transmission gear 91a that rotates integrally with the carrier CR (first carrier CR1) of the first reciprocating unit 5A, which is one of the pair of reciprocating units 5, and the other of the pair of transmission gears 91 is the second transmission gear 91b that rotates integrally with the carrier CR (second carrier CR2) of the second reciprocating unit 5B, which is the other of the pair of reciprocating units 5. And one of the pair of output gears 92 is the first output gear 92a that meshes with the first transmission gear 91a, and the other of the pair of output gears 92 is the second output gear 92b that meshes with the second transmission gear 91b. Since they overlap in Fig. 4, both gears are not visible, but the first output gear 92a and the second output gear 92b are arranged side by side in the axial direction L on the output axis X4. And the first output gear 92a and the second output gear 92b are connected to the output member 4 so that each rotates integrally with the output member 4.

[0040] Similarly, in the pair of the third reciprocating unit 5C and the fourth reciprocating unit 5D, one of the pair of transmission gears 91 is the third transmission gear 91c that rotates integrally with the carrier CR (the third carrier CR3) of the third reciprocating unit 5C which is one of the pair of reciprocating units 5, and the other of the pair of transmission gears 91 is the fourth transmission gear 91d that rotates integrally with the carrier CR (the fourth carrier CR4) of the fourth reciprocating unit 5D which is the other of the pair of reciprocating units 5. And one of the pair of output gears 92 is the first output gear 92a that meshes with the third transmission gear 91c, and the other of the pair of output gears 92 is the second output gear 92b that meshes with the fourth transmission gear 91d.

[0041] When considered as a four-cylinder internal combustion engine, the first output gear 92a meshes with the first transmission gear 91a and the third transmission gear 91c. Also, the second output gear 92b meshes with the second transmission gear 91b and the fourth transmission gear 91d.

[0042] In the third example, a form having two pairs of reciprocating units 5 arranged side by side in the axial direction L is illustrated. Of course, the reciprocating internal combustion engine 10 may have a two-cylinder configuration having one pair of reciprocating units 5 arranged side by side in the axial direction L. Also, the number of reciprocating units 5 arranged side by side in the axial direction L is not limited to two, and may be three or more.

[0043] FIG. 6 shows a fourth example of the reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 of the fourth example has the same structure of the power conversion mechanism as the reciprocating internal combustion engine 10 of the first example, and the configuration of the piston member 8 is different. Since the configuration of the power conversion mechanism is the same as that of the first example, detailed description thereof is omitted.

[0044] In the reciprocating internal combustion engine 10 of the first example, the first connecting portion 85 and the second connecting portion 86 were integrally connected to the piston body 82. However, in the reciprocating internal combustion engine 10 of the fourth example, the first connecting portion 85 and the second connecting portion 86 are integrally connected to the piston body 82 via an intermediate connecting portion 87. The intermediate connecting portion 87 includes an axial connecting portion 88 and a reciprocating connecting portion 89. The axial connecting portion 88 connects the first connecting portion 85 and the second connecting portion 86 in the axial direction L. The reciprocating connecting portion 89 connects the axial connecting portion 88 and the piston body 82 in the reciprocating direction I. The axial connecting portion 88 and the reciprocating connecting portion 89 are fastened and fixed by a fastening member such as a bolt.

[0045] As shown in FIG. 6, the dimension (rod width d88) of the axial connecting portion 88 in the axial direction L is larger than the dimension (piston ring diameter d82) of the piston body 82 in the axial direction L. Further, the reciprocating connecting portion 89 is formed such that the cross section orthogonal to the reciprocating direction I is smaller than that of the piston body 82. Thereby, a space is formed between the piston body 82 and the axial connecting portion 88. Also, with such a configuration, it is easy to secure a large dimension in the axial direction L of the crank member 2 and the planetary gear mechanism 1 that support the piston body 82, and the constraints on the arrangement of the bearings can be reduced. Therefore, even when the load from the piston member 8 is large, the piston member 8 can be appropriately supported.

[0046] As described above by showing the first example to the fourth example, the reciprocating internal combustion engine 10 of the present embodiment can ensure the support strength and rigidity in the linear motion conversion mechanism that converts the linear motion of the piston into a rotational motion and can realize a stable operation.

[0047] Incidentally, in the reciprocating internal combustion engine 10, it is preferable to reduce vibrations generated due to the reciprocating motion. Hereinafter, with reference to FIGS. 7 to 10 as well, the reciprocating internal combustion engine 10 having a function of reducing vibrations associated with the reciprocating motion will be described. FIGS. 7 to 9 show a fifth example of the reciprocating internal combustion engine 10, and FIG. 10 shows a sixth example of the reciprocating internal combustion engine 10. FIG. 7 is a schematic axial orthogonal cross-sectional view of the reciprocating internal combustion engine 10 of the fifth example, and FIGS. 8 and 9 are schematic axial cross-sectional views of the reciprocating internal combustion engine 10 of the fifth example. FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7, and FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 7. Also, for the reciprocating internal combustion engine 10 of the sixth example, the axial orthogonal cross-sectional view is the same as FIG. 7, and FIG. 10 can also be said to be a cross-sectional view taken along line VIII-VIII of FIG. 7 similar to FIG. 8 (when showing the cross-section lines in FIG. 7, the VIII-VIII cross-section line also serves as the X-X cross-section line).

[0048] As shown in FIGS. 7 and 8, in the reciprocating internal combustion engine 10 of the fifth example as well, the transmission mechanism 9 includes a transmission gear 91 that rotates integrally with the carrier CR, and an output gear 92 that meshes with the transmission gear 91 and rotates integrally with the output member 4. Since the configuration of the power transmission mechanism from the piston body 82 to the output gear 92 has been described above with reference to FIGS. 1 to 6, particularly FIG. 6, a detailed description thereof will be omitted.

[0049] The output member 4 of the reciprocating internal combustion engine 10 of the fifth example is also rotatably supported, for example, in the same manner as the reciprocating internal combustion engine 10 of the fourth example, around an output axis X4 parallel to the carrier axis X1. However, the reciprocating internal combustion engine 10 of the fifth example further includes a first counter gear 71 that rotates integrally with the output member 4. Here, the first counter gear 71 is formed to have a larger diameter than the output gear 92. Also, the reciprocating internal combustion engine 10 of the fifth example further includes a counter axis X5 parallel to the carrier axis X1 as a rotation axis. And the reciprocating internal combustion engine 10 of the fifth example includes a counter mechanism including a counter shaft 7 rotatably supported around the counter axis X5 and a second counter gear 72. The second counter gear 72 meshes with the first counter gear 71 and rotates integrally with the counter shaft 7.

[0050] Here, the direction orthogonal to the reciprocating direction I (see FIG. 1) and the axial direction L is defined as the width direction H. One side of the width direction H is the first width side H1, and the other side is the second width side H2. And, an axis along the reciprocating direction I passing through the center of the piston body 82 in the reciprocating direction view is defined as the reciprocating drive axis Y. As shown in FIG. 7, with the reciprocating drive axis Y interposed therebetween, the output axis center X4 is arranged on the first width side H1, and the counter axis center X5 is arranged on the second width side H2. Therefore, the first counter gear 71 is arranged on the first width side H1, and the second counter gear 72 is arranged on the second width side H2. Further, here, in the axial direction view, with the reciprocating drive axis Y as the axis of symmetry, the output axis center X4 and the counter axis center X5 are in a line-symmetric relationship. Therefore, the first counter gear 71 and the second counter gear 72 are arranged at line-symmetric positions with the reciprocating drive axis Y as the axis of symmetry in the axial direction view.

[0051] Also, it is preferable that the first counter gear 71 and the second counter gear 72 are gears of the same diameter and have the same mass, excluding manufacturing errors. Further, as shown in FIGS. 8 and 9, the first counter gear 71 and the second counter gear 72 are each a counterweight integrated gear in which a counterweight 70 is integrally provided on the gear. When distinguishing each counterweight 70, the counterweight 70 of the first counter gear 71 is referred to as the first counter gear weight 73, and the counterweight 70 of the second counter gear 72 is referred to as the second counter gear weight 74.

[0052] For example, in the case of a configuration where the output axis X4, which is the rotation axis of the output member 4, is located on the reciprocating drive shaft Y in the axial direction view (although not shown in the figure, in the first example, the second example, and the fourth example, the output axis X4 is located on the reciprocating drive shaft Y), vibrations in the direction along the reciprocating drive shaft Y are easily suppressed, but vibrations in the width direction H tend to remain. In the reciprocating internal combustion engine 10 of the fifth example, the output axis X4 and the counter axis X5 are arranged separately on both sides in the width direction H with the reciprocating drive shaft Y interposed therebetween, and the first counter gear 71 arranged on the output axis X4 meshes with the second counter gear 72 arranged on the counter axis X5, and both counter gears are provided with counterweights 70. By the movement of the center of gravity along the reciprocating drive shaft Y between the first counter gear weight 73 that rotates around the output axis X4 integrally with the first counter gear 71 and the second counter gear weight 74 that rotates around the counter axis X5 integrally with the second counter gear 72, vibrations in the direction along the reciprocating drive shaft Y can be reduced. Further, the first counter gear weight 73 and the second counter gear weight 74 are arranged separately in the width direction H. Here, with the reciprocating drive shaft Y as the axis of symmetry, counterweights 70 of the same mass are arranged in line symmetry. Therefore, it is easy to cancel out vibrations in the width direction H, and it is easy to reduce such vibrations.

[0053] Also, as shown in FIGS. 8 and 9, the reciprocating internal combustion engine 10 of the fifth example further includes a first counterweight 75 that rotates integrally with the output member 4 and a second counterweight 76 that rotates integrally with the counter shaft 7 independently of the first counterweight 75. The first counterweight 75 and the second counterweight 76 are preferably of the same shape and the same mass except for manufacturing errors. The first counterweight 75 and the second counterweight 76 are arranged with the reciprocating drive shaft Y interposed therebetween, with the first counterweight 75 arranged on the first side H1 in the width direction and the second counterweight 76 arranged on the second side H2 in the width direction, in the same positional relationship as that between the first counter gear 71 and the second counter gear 72. And here, in the axial direction view, with the reciprocating drive shaft Y as the axis of symmetry, the first counterweight 75 and the second counterweight 76 are arranged in a line-symmetrical positional relationship.

[0054] Also, as shown in FIG. 8, the first counter gear 71 and the first counter weight 75 are arranged separately on both sides in the axial direction L with respect to the reciprocating drive shaft Y and the output gear 92. It is preferable that the first counter gear 71 and the first counter weight 75 are arranged at the same distance from each other in the axial direction L with respect to the reciprocating drive shaft Y. Alternatively, the first counter gear 71 and the first counter weight 75 may be arranged at the same distance from each other in the axial direction L with respect to the output gear 92.

[0055] Also, as shown in FIG. 9, the second counter gear 72 and the second counter weight 76 are also arranged separately on both sides in the axial direction L with respect to the reciprocating drive shaft Y. It is preferable that the second counter gear 72 and the second counter weight 76 are arranged at the same distance from each other in the axial direction L with respect to the reciprocating drive shaft Y. Incidentally, when the first counter gear 71 and the first counter weight 75 are arranged at the same distance from each other in the axial direction L with respect to the output gear 92, it is preferable that the second counter weight 76 is arranged at a position corresponding to the first counter weight 75 in the axial direction L. Since the first counter gear 71 and the second counter gear 72 mesh with each other, the second counter gear 72 is arranged at a position corresponding to the first counter gear 71 in the axial direction L. Therefore, by making the arrangement positions of the first counter weight 75 and the second counter weight 76 in the axial direction L coincide with each other, the weight balance between the first counter gear weight 73 and the first counter weight 75 at the output axis X4 and the weight balance between the second counter gear weight 74 and the second counter weight 76 at the counter axis X5 can be made equal.

[0056] By providing the first counterweight 75 and the second counterweight 76 in this way, the vibration in the width direction H can be more appropriately reduced. Further, the first counter gear 71 provided with the first counter gear weight 73 and the first counterweight 75 are arranged on both sides in the axial direction L with the reciprocating drive shaft Y interposed therebetween, and the second counter gear 72 provided with the second counter gear weight 74 and the second counterweight 76 are arranged on both sides in the axial direction L with the reciprocating drive shaft Y interposed therebetween. By doing so, it is easy to achieve weight balance in the axial direction L and suppress vibration in the axial direction L.

[0057] In addition to the above, the moment of the first counter gear weight 73 and the first counterweight 75 about their output axis X4 is opposite to the sum of the moments of the second counter gear weight 74 and the second counterweight 76 about the counter axis X5 and is configured to have the same magnitude. For this reason, the total mass of the first counter gear weight 73 and the first counterweight 75 is made the same as the total mass of the second counter gear weight 74 and the second counterweight 76. According to this configuration, the vibration in the width direction H generated by rotating the output member 4 is appropriately reduced by the counter mechanism.

[0058] Furthermore, in a state where the piston body 82 is located at each of the top dead center and the bottom dead center, the resultant force of the centrifugal forces acting on each of the first counter gear weight 73, the first counterweight 75, the second counter gear weight 74, and the second counterweight 76 is opposite to the resultant force of the inertial force acting on the piston member 8 and the centrifugal force acting on the crank member 2 and is configured to have the same magnitude. For this reason, the center of gravity positions and masses of the first counter gear weight 73, the first counterweight 75, the second counter gear weight 74, and the second counterweight 76 are determined in consideration of the inertial force acting on the piston body 82 and the centrifugal force of the crank member 2 in a state where the piston body 82 is located at each of the top dead center and the bottom dead center. According to this configuration, the vibration generated along with the reciprocating motion of the piston member 8 and the crank member 2 can be effectively reduced.

[0059] As described above, with reference to FIGS. 7 to 9, considering the weight balance in the axial direction L, the balance between the moment around the output axis X4 and the moment around the counter axis X5, and the balance of the forces acting on each component of the reciprocating internal combustion engine 10, the configuration of the fifth example of the reciprocating internal combustion engine 10 provided with not only the first counter gear weight 73 and the second counter gear weight 74 but also the first counter weight 75 and the second counter weight 76 has been described. However, a configuration without the first counter weight 75 and the second counter weight 76, such as the sixth example of the reciprocating internal combustion engine 10 illustrated in FIG. 10, is not precluded.

[0060] The cylinder 81 in which the piston body 82 reciprocates along the reciprocating direction I has a cylindrical shape with an inner diameter equal to the piston ring diameter d82. On the other hand, the portion of the case 6 in which the connecting rod 83 is accommodated is formed in a rectangular prism shape in cross section, or in a cylindrical shape with an elliptical or track-shaped cross section. That is, the inner dimension in the width direction H (width direction dimension d61 (see FIG. 7)) and the inner dimension in the axial direction L (axial direction dimension d62 (see FIGS. 8 to 10)) are different, and here the axial direction dimension d62 is longer than the width direction dimension d61. As is clear from a comparison between FIG. 8 and FIG. 10, the axial direction dimension d62 in the sixth example of the reciprocating internal combustion engine 10 is shorter than the axial direction dimension d62 in the fifth example of the reciprocating internal combustion engine 10. That is, when not provided with the first counter weight 75 and the second counter weight 76, as in the sixth example of the reciprocating internal combustion engine 10, the axial direction dimension d62 can be made smaller than that in the fifth example of the reciprocating internal combustion engine 10 provided with the first counter weight 75 and the second counter weight 76, and the reciprocating internal combustion engine 10 can be easily miniaturized.

[0061] Furthermore, in the reciprocating internal combustion engine 10, in addition to reducing the vibrations generated due to the reciprocating motion, it is preferable that there is a high degree of freedom in setting the overall shape. For example, in order to suppress the vibrations in the width direction H, the reciprocating internal combustion engine 10 preferably has the shape on the first width side H1 and the shape on the second width side H2 that are line-symmetrical with the reciprocating drive shaft Y as the axis of symmetry, as in the fifth and sixth examples. However, the positional relationship among the connecting rod 83, the output gear 92, and the counter gear 93 may be one of the constraints in setting the overall shape. Therefore, in the seventh example, the rotation of the transmission gear 91 is configured to be directly transmitted to both the output gear 92 and the counter gear 93, thereby reducing vibrations while increasing the degree of freedom in setting the overall shape.

[0062] Hereinafter, with reference to FIGS. 11 to 13, a reciprocating internal combustion engine 10 that, in addition to the function of reducing vibrations associated with the reciprocating motion, has an increased degree of freedom in setting the overall shape will be described. FIGS. 11 to 13 show a seventh example of the reciprocating internal combustion engine 10. FIG. 11 is a schematic orthogonal cross-sectional view of the seventh example of the reciprocating internal combustion engine 10, and FIG. 12 is a cross-sectional view taken along line XII-XII of FIG. 11. FIG. 12 shows a state in which the piston body 82 of FIG. 11 is located at the bottom dead center.

[0063] As shown in FIGS. 11 and 12, in the reciprocating internal combustion engine 10 of the seventh example, the transmission mechanism 9 also includes a transmission gear 91 that rotates integrally with the carrier CR, and an output gear 92 that meshes with the transmission gear 91 and rotates integrally with the output member 4. Since the configuration of the power transmission mechanism from the piston body 82 to the transmission gear 91 has been described above with reference to FIGS. 1 to 6, particularly FIG. 6, a detailed description thereof will be omitted. In addition, the reciprocating direction I, the reciprocating drive shaft Y, and the width direction H are also as described above with reference to FIGS. 1 to 10. Here, in the following description, the side closer to the piston member 8 in the reciprocating direction I is referred to as the first reciprocating side I1, and the opposite side is referred to as the second reciprocating side I2.

[0064] The output member 4 of the reciprocating internal combustion engine 10 of the seventh example is also rotatably supported about an output axis X4 parallel to the carrier axis X1, similar to the reciprocating internal combustion engine 10 of the fourth and fifth examples. However, the reciprocating internal combustion engine 10 of the seventh example further includes a counter mechanism including a counter shaft 7 rotatably supported about a counter axis X5 parallel to the carrier axis X1 and a counter gear 93. The counter gear 93 meshes with the transmission gear 91 and rotates integrally with the counter shaft 7. According to this configuration, since both the output gear 92 and the counter gear 93 mesh with the transmission gear 91, the axial dimension d62 of the case 6 (see FIG. 12) can be easily set shorter compared to the axial dimension d62 of the case 6 in the fifth example (see FIG. 9) and the axial dimension d62 of the case 6 in the sixth example (see FIG. 10). In addition, in the example shown in FIG. 11, the transmission gear 91, the output gear 92, and the counter gear 93 are arranged to be located between the first connecting portion 85 and the second connecting portion 86 in the axial direction L. In addition, in the example shown in FIG. 11, the carrier axis X1 is arranged at a position intersecting the reciprocating drive shaft Y. According to this configuration, it is easy to set the overall shape of the reciprocating internal combustion engine 10 to be line-symmetric in the width direction H with the reciprocating drive shaft Y as the axis of symmetry. As a result, it is easy to cancel out the vibration in the width direction H of the reciprocating internal combustion engine 10.

[0065] In the present embodiment, the transmission gear 91, the output gear 92, and the counter gear 93 are meshed so as to rotate at the same speed as each other. That is, the number of teeth of the transmission gear 91, the output gear 92, and the counter gear 93 are made the same. In addition, in the present embodiment, the transmission gear 91, the output gear 92, and the counter gear 93 have the same diameter except for manufacturing errors.

[0066] As shown in FIGS. 10 and 11, the transmission gear 91, the output gear 92, and the counter gear 93 are each a counterweight-integrated gear in which a counterweight 70 is integrally provided on the gear. Here, when distinguishing each counterweight 70, the counterweight 70 of the transmission gear 91 is referred to as a gear weight 101. And, the counterweight 70 of the output gear 92 is referred to as a first gear weight 102, and the counterweight 70 of the counter gear 93 is referred to as a second gear weight 103.

[0067] In the seventh example, the gear weight 101 is a portion that protrudes in the axial direction L from the transmission gear 91. In FIG. 12, the gear weight 101 is provided at two positions on the transmission gear 91, namely, the first axial side L1 and the second axial side L2. And, in the seventh example, the first gear weight 102 and the second gear weight 103 are also portions that protrude in the axial direction L from the output gear 92 and the counter gear 93, respectively. In FIG. 12, the first gear weight 102 is provided at a position on the first axial side L1 with respect to the output gear 92. Although the position of the second gear weight 103 with respect to the counter gear 93 is not shown in the figure, it is preferable to arrange it in the same positional relationship as that between the output gear 92 and the first gear weight 102. For example, when the first gear weight 102 is arranged on the first axial side L1 with respect to the output gear 92 as described above, it is preferable that the second gear weight 103 is also arranged on the first axial side L1 with respect to the counter gear 93. According to this configuration, it is easy to reduce the size of the axial dimension L of the reciprocating internal combustion engine 10.

[0068] The first gear weight 102 is provided on the output gear 92 such that the magnitude of the moment around its output axis X4 is the same as the magnitude of the moment around the counter axis X5 by the second gear weight 103. In the example shown in FIG. 11, the distance from the output axis X4 to the center-of-gravity position of the first gear weight 102 is made the same as the distance from the counter axis X5 to the center-of-gravity position of the second gear weight 103. And, the first gear weight 102 has the same mass as the second gear weight 103.

[0069] The gear weight 101 is provided on the transmission gear 91 such that the moment about its carrier axis X1 is opposite to and equal in magnitude to the sum of the moment about the output axis X4 by the first gear weight 102 and the moment about the counter axis X5 by the second gear weight 103. For this reason, in the seventh example, the distance from the carrier axis X1 to the center of gravity position of the gear weight 101 is made the same as the distance from the output axis X4 to the center of gravity position of the first gear weight 102 (the center of gravity position of the second gear weight 103 from the counter axis X5). And the mass of the gear weight 101 is made the same as the sum of the mass of the first gear weight 102 and the mass of the second gear weight 103. That is, the mass of the gear weight 101 is made twice the respective masses of the first gear weight 102 and the second gear weight 103.

[0070] Also, in the reciprocating internal combustion engine 10 of the seventh example, in the state where the piston body 82 is located at the top dead center and the bottom dead center respectively, the resultant force of the centrifugal forces acting on each of the gear weight 101, the first gear weight 102, and the second gear weight 103 is opposite to and equal in magnitude to the resultant force of the inertial force acting on the piston member 8 and the centrifugal force acting on the crank member 2. For this reason, the masses of the gear weight 101, the first gear weight 102, and the second gear weight 103 are determined in consideration of the inertial force acting on the piston body 82 in the state where the piston body 82 is located at the top dead center and the bottom dead center respectively, and the centrifugal force of the crank member 2. According to this configuration, the vibration generated along with the reciprocating motion of the piston member 8 and the crank member 2 can be effectively reduced.

[0071] For example, as shown in FIG. 11, when the piston body 82 is positioned at the top dead center, the center-of-gravity positions of the gear weight 101, the first gear weight 102, and the second gear weight 103 are each located on the second side I2 in the reciprocating direction with respect to their respective rotation centers. Specifically, the center-of-gravity position of the gear weight 101 is located on the second side I2 in the reciprocating direction of the carrier axis X1, the center-of-gravity position of the first gear weight 102 is located on the second side I2 in the reciprocating direction of the output axis X4, and the center-of-gravity position of the second gear weight 103 is located on the second side I2 in the reciprocating direction of the counter axis X5. Therefore, a centrifugal force toward the second side I2 in the reciprocating direction acts on each of the gear weight 101, the first gear weight 102, and the second gear weight 103. And since the crank member 2 is located on the first side I1 in the reciprocating direction with respect to the carrier axis X1 which is its rotation center, a centrifugal force toward the first side I1 in the reciprocating direction acts. In addition, as shown in FIG. 11, an inertial force toward the first side I1 in the reciprocating direction acts on the piston body 82 positioned at the top dead center.

[0072] On the other hand, as shown in FIG. 13, when the piston body 82 is positioned at the bottom dead center, the center-of-gravity positions of the gear weight 101, the first gear weight 102, and the second gear weight 103 are each located on the first side I1 in the reciprocating direction with respect to their respective rotation centers. Therefore, a centrifugal force toward the first side I1 in the reciprocating direction acts on each of the gear weight 101, the first gear weight 102, and the second gear weight 103. And since the crank member 2 is located on the second side I2 in the reciprocating direction with respect to the carrier axis X1 which is its rotation center, a centrifugal force toward the second side I2 in the reciprocating direction acts. In addition, as shown in FIG. 13, an inertial force toward the second side I2 in the reciprocating direction acts on the piston body 82 positioned at the bottom dead center.

[0073] Furthermore, as shown in FIGS. 11 and 13, in the reciprocating internal combustion engine 10 of the seventh example, the output axis X4 is on the first side H1 in the width direction with respect to the carrier axis X1, and is arranged at a position in the same reciprocating direction I as the carrier axis X1 or at a position on the first side I1 of the reciprocating direction. The output axis X4 illustrated in FIGS. 11 and 13 is on the first side H1 in the width direction with respect to the carrier axis X1 and is arranged at a position on the first side I1 of the reciprocating direction. On the other hand, the counter axis X5 is on the second side H2 in the width direction with respect to the carrier axis X1, and is arranged at a position in the same reciprocating direction I as the carrier axis X1 or at a position on the first side I1 of the reciprocating direction with respect to the carrier axis X1 in the reciprocating direction I. The counter axis X5 illustrated in FIGS. 11 and 13 is on the second side H2 in the width direction with respect to the carrier axis X1 and is arranged at a position on the first side I1 of the reciprocating direction.

[0074] Also, in the examples shown in FIGS. 11 and 13, in the axial view, with the reciprocating drive shaft Y as the axis of symmetry, the output axis X4 and the counter axis X5 are in a line-symmetrical relationship. Therefore, the first counter gear 71 and the second counter gear 72 are arranged at line-symmetrical positions with the reciprocating drive shaft Y as the axis of symmetry in the axial view.

[0075] In addition to reducing the vibration generated along with the reciprocating motion of the piston member 8 and the like, it is preferable that the rotational speed of the output member 4 is different from the rotational speeds of the rotating elements included in the transmission mechanism 9 such as the transmission gear 91 in the reciprocating internal combustion engine 10. In particular, as illustrated in FIGS. 15 and 17, in the reciprocating internal combustion engine 10 that outputs the rotational force of the output member 4 to the generator MG, it is preferable to rotate the generator MG at a rotational speed higher than the rotational speed at which the reciprocating unit 5 rotates the carrier CR. By doing so, it is easy to set the generator MG that outputs the rotational force to the reciprocating internal combustion engine 10 to one with high power generation efficiency. Therefore, as the eighth and ninth examples, in addition to reducing the vibration generated along with the reciprocating motion of the piston member 8 and the like, the configuration is such that the rotational speed of the output member 4 is different from the rotational speeds of the rotating elements included in the transmission gear 91 and the like.

[0076] Hereinafter, with reference to FIGS. 14 to 17, the reciprocating internal combustion engine 10 of the eighth example and the ninth example will be described. Here, FIGS. 14 and 15 show the eighth example of the reciprocating internal combustion engine 10. FIG. 14 is a schematic axial orthogonal sectional view of the eighth example of the reciprocating internal combustion engine 10, and FIG. 15 is a sectional view taken along the line XV-XV of FIG. 14. FIGS. 16 and 17 show the ninth example of the reciprocating internal combustion engine 10. FIG. 16 is a schematic axial orthogonal sectional view of the ninth example of the reciprocating internal combustion engine 10, and FIG. 17 is a sectional view taken along the line XVII-XVII of FIG. 16. The reciprocating internal combustion engines 10 of the eighth example and the ninth example differ from the reciprocating internal combustion engines 10 of the fifth to seventh examples in the configuration of the transmission mechanism 9. Hereinafter, the points in which the configurations of the reciprocating internal combustion engines 10 of the eighth example and the ninth example differ from the configurations of the reciprocating internal combustion engines 10 of the fifth to seventh examples will be mainly described. And the description of the common configurations between the reciprocating internal combustion engines 10 of the eighth example and the ninth example and the reciprocating internal combustion engines 10 of the fifth to seventh examples will be omitted.

[0077] In the reciprocating internal combustion engine 10 of the eighth example, as shown in FIGS. 14 and 15, the transmission mechanism 9 includes a transmission gear 91, a first counter mechanism C1, a second counter mechanism C2, and an output gear CK. In the reciprocating internal combustion engine 10 of the eighth example as well, the transmission gear 91 rotates integrally with the carrier CR. In addition, in the reciprocating internal combustion engine 10 of the eighth example, a generator MG is drivingly connected to the output member 4.

[0078] The first counter mechanism C1 includes a first counter shaft C11 rotatably supported around a first counter axis X51 parallel to the carrier axis X1, and a first counter gear C12 that meshes with the transmission gear 91 and rotates integrally with the first counter shaft C11. In the example shown in FIG. 14, the first counter shaft C11 is disposed on the first side H1 in the width direction with respect to the reciprocating drive shaft Y. And both end portions in the axial direction L of the first counter shaft C11 are rotatably supported by the case 6 via bearings respectively. The first counter gear C12 is in a position overlapping the transmission gear 91 when viewed from the radial direction R, and is disposed on the outer peripheral surface at an intermediate position in the axial direction L of the first counter shaft C11. In the example shown in FIG. 15, the first counter gear C12 has an integral structure with the first counter shaft C11.

[0079] In the example shown in FIG. 15, a weight CW is provided in at least a part of a circumferential region that circulates around the first counter axis X51 at an outer end in the radial direction R of the first counter gear C12. The weight CW is a weight provided to adjust the magnitude of the moment of inertia generated when the first counter gear C12 rotates. In the example shown in FIG. 15, the weight CW has an integral structure with the first counter gear C12 and is formed on the surface of the first side L1 in the axial direction of the first counter gear. The region where the weight CW is formed in the first counter gear C12 and the weight of the weight CW are appropriately determined according to the magnitude of the moment of inertia required to reduce the vibration of the entire reciprocating internal combustion engine 10.

[0080] The second counter mechanism C2 includes a second counter shaft C21 rotatably supported around a second counter axis X52 parallel to the carrier axis X1, and a second counter gear C22 that meshes with the transmission gear 91 and rotates integrally with the second counter shaft C21. In the example shown in FIG. 14, the second counter shaft C21 is disposed on the second side H2 in the width direction with respect to the reciprocating drive shaft Y. The second counter shaft C21 is also, although not shown, similar to the first counter shaft C11 in that both end portions in the axial direction L are rotatably supported by the case 6 via bearings. The second counter gear C22 is also, although not shown, similar to the first counter gear C12 in that it is located at a position overlapping the transmission gear 91 when viewed from the radial direction R and is disposed on the outer peripheral surface at an intermediate position in the axial direction L of the second counter shaft C21. And the second counter gear C22 also has an integral structure with the second counter shaft C21, similar to the first counter gear C12.

[0081] Also, in the eighth example, although not shown, similar to the first counter gear C12, a weight CW is provided in at least a part of the circumferential region that orbits around the second counter axis center X52 on the second counter gear C22. By providing the weight CW on both the first counter gear C12 and the second counter gear C22, at least a part of the moment of inertia generated in the first counter gear C12 can be canceled out by the moment of inertia generated in the second counter gear C22. Therefore, the vibration generated in the reciprocating internal combustion engine 10 can be reduced.

[0082] The output gear CK meshes with at least one of the gear that rotates integrally with the first counter shaft C11 and the gear that rotates integrally with the second counter shaft C21 and rotates integrally with the output member 4. In the eighth example, the output member 4 includes an output shaft CK1 arranged along the output axis center X4 in addition to the output gear CK. In the example shown in FIG. 15, the output axis center X4 is arranged on the first side H1 in the width direction with respect to the reciprocating drive shaft Y. In addition, the output axis center X4 is arranged on the second side I2 in the reciprocating direction with respect to the carrier axis center X1.

[0083] In the example shown in FIG. 15, the output gear CK is provided on the outer peripheral surface of the output shaft CK1. Both end portions of the output shaft CK1 in the axial direction L are rotatably supported by the case 6 via bearings, respectively. In the example shown in FIG. 15, the output gear CK is formed at an intermediate position in the axial direction L of the output shaft CK1. And the output gear CK has an integral structure with the output shaft CK1.

[0084] In the examples shown in FIGS. 14 and 15, the output gear CK meshes with an intermediate gear C13 that rotates integrally with the first countershaft C11 or the second countershaft C21. In the example shown in FIG. 15, the intermediate gear C13 is arranged at different positions in the axial direction L with respect to the first counter gear C12. Specifically, the intermediate gear C13 is located at a position on the outer peripheral surface of the first countershaft C11 and at a position on the second side L2 in the axial direction with respect to the first counter gear C12. In the example shown in FIG. 15, the intermediate gear C13 has an integral structure with the first countershaft C11. In addition, the intermediate gear C13 is arranged on the second side L2 in the axial direction with respect to the planetary gear mechanism 1. Therefore, it is easy to secure a space in the radial direction R with respect to the installation position of the intermediate gear C13 in the axial direction L, and it is easy to set the intermediate gear C13 large in the radial direction R. For this reason, it is easy to set a relatively large reduction ratio of the rotation of the first countershaft C11 with respect to the rotation of the output shaft CK1.

[0085] Also, it is preferable that an intermediate weight CW1 is provided in at least one of the first counter mechanism C1 and the second counter mechanism C2. The intermediate weight CW1 is a weight having at least one of a function of adjusting the moment of inertia of the first countershaft C11 or the second countershaft C21 and a function of a flywheel that suppresses sudden changes in the rotation of the intermediate gear C13. In the example shown in FIG. 15, the intermediate weight CW1 is provided on the intermediate gear C13. Specifically, the intermediate weight CW1 is provided on the surface on the second side L2 in the axial direction of the outer end portion in the radial direction R of the intermediate gear C13. And the intermediate weight CW1 is provided in at least a part of the region in the circumferential direction that circulates around the rotation axis of the intermediate gear C13. In the example shown in FIG. 15, the intermediate weight CW1 has an integral structure with the intermediate gear C13 and is arranged over the entire circumference in the circumferential direction. For this reason, the intermediate weight CW1 can have both a function of adjusting the moment of inertia of the first countershaft C11 and a function as a flywheel.

[0086] The output member 4 is configured such that the moment of inertia of the member rotating around the carrier axis X1 and the member rotating around the output axis X4 (output moment of inertia) and the moment of inertia of the member rotating around the first counter axis X51 and the member rotating around the second counter axis X52 (counter moment of inertia) cancel each other out. In the eighth example, the output moment of inertia and the counter moment of inertia are configured to balance each other. Specifically, the output member 4 includes an output weight CW2 that is a weight for adjusting the magnitude of the output moment of inertia.

[0087] The installation position, size, and range of the output weight CW2 with respect to the output member 4 are set such that the output moment of inertia balances the counter moment of inertia. In the example shown in FIG. 15, the output weight CW2 is provided on the outer peripheral surface of the output shaft CK1. In addition, the output weight CW2 is arranged at an interval in the first axial direction L1 with respect to the output gear CK and is arranged in the region between the first counter gear C12 and the intermediate gear C13. According to this configuration, it is easy to secure the installation space of the output gear CK in the radial direction R, and it is easy to adjust the magnitude of the output moment of inertia.

[0088] In the transmission mechanism 9 described above, it is preferable that the gear ratio of the output gear CK and the gear meshing with the output gear CK is set such that the rotational speed of the output member 4 is higher than the rotational speeds of the first counter shaft C11 and the second counter shaft C21. According to this configuration, the output member 4 can rotate the generator MG at a high rotational speed. In the example shown in FIG. 15, the output member 4 is configured such that its rotational speed is higher than the rotational speed of the first counter shaft C11. Specifically, in the example shown in FIG. 15, the rotation of the first counter shaft C11 is transmitted from the intermediate gear C13 meshing with the output gear CK, and the intermediate gear C13 is set to have a larger diameter than the output gear CK. And in the example shown in FIG. 15, since the output shaft CK1 rotates at a high rotational speed, the output shaft CK1 is configured to rotate integrally with the rotor of the generator MG. That is, the output shaft CK1 is drivingly connected to the rotor of the generator MG.

[0089] As shown in FIGS. 16 and 17, in the reciprocating internal combustion engine 10 of the ninth example, the configurations of the first counter mechanism C1, the second counter mechanism C2, and the output member 4 are different from those of the reciprocating internal combustion engine 10 of the eighth example. Hereinafter, the differences between the reciprocating internal combustion engine 10 of the ninth example and the reciprocating internal combustion engine 10 of the eighth example will be described, and the description of the configurations common to the reciprocating internal combustion engine 10 of the ninth example and the reciprocating internal combustion engine 10 of the eighth example will be omitted.

[0090] In the reciprocating internal combustion engine 10 of the ninth example, as shown in FIGS. 16 and 17, the first counter mechanism C1 further includes a third counter gear C3 that is arranged at a position different from the first counter gear C12 in the axial direction L and rotates integrally with the first counter shaft C11. Specifically, the third counter gear C3 is located on the outer peripheral surface of the first counter shaft C11 and is arranged at a position on the second side L2 in the axial direction with respect to the first counter gear C12. In the example shown in FIG. 17, the third counter gear C3 has an integral structure with the first counter shaft C11. In addition, the third counter gear C3 is arranged on the second side L2 in the axial direction with respect to the planetary gear mechanism 1. Therefore, it is easy to secure a space in the radial direction R with respect to the installation position of the third counter gear C3 in the axial direction L, and it is easy to set the third counter gear C3 large in the radial direction R. For this reason, it is easy to set a relatively large reduction ratio of the rotation of the first counter shaft C11 with respect to the rotation of the output shaft CK1.

[0091] The second counter mechanism C2 further includes a fourth counter gear C4 that is arranged at a position different from the second counter gear C22 in the axial direction L and rotates integrally with the second counter shaft C21. Specifically, although not shown, the fourth counter gear C4 is located on the outer peripheral surface of the second counter shaft C21 and is arranged at a position on the second side L2 in the axial direction with respect to the second counter gear C22. And the fourth counter gear C4 has an integral structure with the second counter shaft C21. In addition, the fourth counter gear C4 is arranged on the second side L2 in the axial direction with respect to the planetary gear mechanism 1. Therefore, it is easy to secure a space in the radial direction R with respect to the installation position of the fourth counter gear C4 in the axial direction L, and it is easy to set the fourth counter gear C4 large in the radial direction R. For this reason, it is easy to match the dimension of the fourth counter gear C4 in the radial direction R with the dimension of the third counter gear C3 in the radial direction R, and it is easy to adjust the magnitude of the counter inertia moment.

[0092] It is preferable that the first counter mechanism C1 and the second counter mechanism C2 are arranged in a line-symmetrical positional relationship in the width direction H with the reciprocating drive shaft Y as the target axis. According to this configuration, it is easy to configure such that the inertia moments of the member rotating around the first counter axis center X51 and the member rotating around the second counter axis center X52 cancel each other out. Therefore, it is easy to reduce the vibration of the reciprocating internal combustion engine 10.

[0093] In the ninth example, the output gear CK is configured to mesh with both the third counter gear C3 and the fourth counter gear C4. According to this configuration, since the output gear CK meshes with both the third counter gear C3 and the fourth counter gear C4, it is possible to suppress the radial R eccentric load acting on the output gear CK and the output member 4 to a small level. Therefore, it is easy to reduce the weight of the output gear CK and the output member 4.

[0094] Next, other embodiments of the reciprocating internal combustion engine 10 will be described.

[0095] 〔Other Embodiments〕 (1) In the above-described embodiment, it has been described that the generator MG is drivingly connected to the output member 4. Here, in the present application, "drivingly connected" means a state in which two rotating elements are connected so as to be able to transmit a driving force, a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or with speed change, for example, shafts, gear mechanisms, belts, chains, and the like. Note that the transmission members may include engaging devices that selectively transmit rotation and driving force, for example, friction engaging devices, meshing engaging devices, and the like.

[0096] (2) In the above-described eighth and ninth examples, it has been described that the generator MG is drivingly connected to the output member 4. However, what is drivingly connected to the output member 4 is not limited to the generator MG, and any device that can output the rotational force generated by the reciprocating unit 5 may be used. For example, a device that directly uses the rotational force generated by the reciprocating unit 5 as power may be drivingly connected to the output member 4.

[0097] (3) In the above-described eighth example, it has been described that the output gear CK meshes with the intermediate gear C13 that rotates integrally with the first countershaft C11. However, the output gear CK is not limited to a configuration that meshes with the intermediate gear C13, and any configuration that meshes with at least one of the gear that rotates integrally with the first countershaft C11 and the gear that rotates integrally with the second countershaft C21 may be used. For example, the output gear CK may be configured to mesh with the first counter gear C12 or the second counter gear C22.

[0098] (4) In the above eighth example, it was explained that the installation position, size, and range of the output weight CW2 with respect to the output member 4 are set such that the output moment of inertia balances the counter moment of inertia. However, the installation position, size, and range of the output weight CW2 do not necessarily have to be set such that the output moment of inertia perfectly balances the counter moment of inertia. That is, the installation position, size, and range of the output weight CW2 may be set such that the output moment of inertia cancels out a part of the counter moment of inertia.

[0099] (5) In the reciprocating internal combustion engine 10 of the above eighth example, it was explained that the output axis X4 is arranged on the first side H1 in the width direction with respect to the reciprocating drive shaft Y, and the output gear CK meshes with the intermediate gear C13. However, the output axis X4 may be arranged on the second side H2 in the width direction with respect to the reciprocating drive shaft Y. In this case, the output member 4 may mesh with the second counter gear C22. And, for example, the second counter gear C22 may be configured to mesh with both the output gear CK provided on the output member 4 and the transmission gear 91. Also, a configuration corresponding to the intermediate gear C13 may be provided on the second counter gear C22, and the transmission gear 91 and the second counter gear C22 may mesh, and the intermediate gear C13 provided on the second counter shaft C21 and the output gear CK may be configured to mesh.

[0100] (6) In the reciprocating internal combustion engine 10 of the above eighth and ninth examples, it was explained that the first counter axis X51 and the second counter axis X52 are arranged at the same position in the reciprocating direction I or at the position on the second side I2 in the reciprocating direction with respect to the carrier axis X1. However, at least one of the first counter axis X51 and the second counter axis X52 may be arranged at the position on the first side I1 in the reciprocating direction with respect to the carrier axis X1.

[0101] (7) Further, the configurations disclosed in the above-described embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs. Regarding other configurations as well, all of the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate without departing from the gist of the present disclosure.

[0102] Hereinafter, the reciprocating internal combustion engine (10) described above will be briefly summarized.

[0103] In one aspect, a reciprocating internal combustion engine (10) includes a planetary gear mechanism (1) having an internal gear ring gear (RG), a carrier (CR) rotatably supported with respect to the ring gear (RG), and a planetary gear (PG) rotatably supported with respect to the carrier (CR) and meshing with the ring gear (RG). With the direction along the carrier axis (X1), which is the axis of rotation of the carrier (CR), defined as the axial direction (L), the direction orthogonal to the carrier axis (X1) defined as the radial direction (R), and the direction orthogonal to the planetary axis (X2), which is the axis of rotation of the planetary gear (PG), defined as the planetary radial direction (Rp), a crank member (2) connected to rotate integrally with the planetary gear (PG), a piston member (8) connected to be relatively rotatable about an input axis (X3) set at a position spaced apart from the planetary axis (X2) in the planetary radial direction (Rp) with respect to the crank member (2), and a transmission mechanism (9) for transmitting the rotation of the carrier (CR) to an output member (4). The radius (r1) of the ring gear (RG) is twice the radius (r2) of the planetary gear (PG). A pair of planetary bearings (B1) for rotatably supporting the planetary gear (PG) with respect to the carrier (CR) are arranged on both sides of the planetary gear (PG) in the axial direction (L). A pair of carrier bearings (B2) for rotatably supporting the carrier (CR) with respect to the ring gear (RG) are arranged on both sides of the ring gear (RG) in the axial direction (L). The crank member (2) includes a first crank portion (21) and a second crank portion (22), which are a pair of crank portions arranged on both sides of the carrier (CR) in the axial direction (L). The piston member (8) includes a piston body (82) and a first connecting portion (85) and a second connecting portion (86), which are a pair of connecting portions connected to the piston body (82) and arranged on both sides of the carrier (CR) in the axial direction (L). The first crank portion (21) and the second crank portion (22) are arranged to extend in the planetary radial direction (Rp). The first connecting portion (85) is connected to the first crank portion (21) to be relatively rotatable about the input axis (X3), and the second connecting portion (86) isIt is connected to the second crank portion (22) so as to be relatively rotatable about the input axis (X3).

[0104] According to this configuration, the reciprocating motion of the piston member (8) can be converted into the rotational motion of the output member (4) and output. Further, according to this configuration, the planetary gear (PG) is rotatably supported with respect to the carrier (CR) on both sides in the axial direction (L), and the carrier (CR) is rotatably supported with respect to the ring gear (RG) on both sides in the axial direction (L). Therefore, even when a load biased in the axial direction (L) acts on the planetary gear (PG) via the crank member (2), the load can be appropriately supported. For this reason, it is easier to extend the service life of the planetary gear mechanism (1) and the transmission mechanism (9) compared to the case where the planetary gear (PG) etc. is cantilever-supported. Furthermore, according to this configuration, the pair of connecting portions (83) of the piston member (8) and the pair of crank portions (2) are arranged separately on both sides in the axial direction (L) with respect to the carrier (CR), and each is relatively rotatably connected about the input axis (X3). Therefore, it is easy to ensure the rigidity of the support structure of the piston member (8), and it is easy to stabilize the operations of the piston member (8) and the crank member (2). As described above, according to this configuration, it is possible to provide a reciprocating internal combustion engine (10) that can ensure the rigidity of the linear motion conversion mechanism that converts the linear motion of the piston into rotational motion and can achieve a stable operation.

[0105] Further, in the reciprocating internal combustion engine (10), it is preferable that the radius (r2) of the planetary gear (PG) and the distance (d23) in the planetary radial direction (Rp) between the planetary axis (X2) and the input axis (X3) are the same, and the first connecting portion (85) and the second connecting portion (86) are integrally connected to the piston body (82).

[0106] According to this configuration, the locus of the reciprocating motion of the input axis (X3) can be made linear, and thereby a configuration in which the piston body (82) and the pair of connecting portions (83) are integrally connected can be achieved. Therefore, it is easy to increase the rigidity of the piston member (8), and it is easy to further stabilize the operations of the piston member (8) and the crank member (2).

[0107] Further, in the reciprocating internal combustion engine (10), with the direction in which the piston body (82) reciprocates being the reciprocating direction (I), the first connecting portion (85) and the second connecting portion (86) are integrally connected to the piston body (82) via an intermediate connecting portion (87). The intermediate connecting portion (87) includes an axial connecting portion (88) that connects the first connecting portion (85) and the second connecting portion (86) in the axial direction (L), and a reciprocating direction connecting portion (89) that connects the axial connecting portion (88) and the piston body (82) in the reciprocating direction (I). The dimension (d88) of the axial connecting portion (88) in the axial direction (L) is larger than the dimension (d82) of the piston body (82) in the axial direction (L), and it is preferable that the reciprocating direction connecting portion (89) is formed such that a cross-section orthogonal to the reciprocating direction (I) is smaller than the piston body (82).

[0108] According to this configuration, it is easy to ensure a large dimension in the axial direction (L) of the crank member (2) and the planetary gear mechanism (1) that support the piston body (82), and the constraints on the arrangement of the bearings can be reduced. Therefore, even when the load from the piston member (8) is large, the piston member (8) can be appropriately supported.

[0109] Further, the reciprocating internal combustion engine (10) includes a transmission gear (91) that rotates integrally with the carrier (CR), and an output gear (92) that meshes with the transmission gear (91) and rotates integrally with the output member (4). The output gear (92) and the output member (4) are rotatably supported around an output axis (X4) parallel to the carrier axis (X1), and it is preferable that the transmission gear (91) and the output gear (92) are arranged between the axial directions (L) of the pair of carrier bearings (B2).

[0110] A structure that transmits rotation from a carrier (CR) to an output member (4) via a transmission gear (91) and an output gear (92) can easily increase the degree of freedom in the arrangement of the output member (4). And in this structure, since the transmission gear (91) and the output gear (92) are arranged between a pair of carrier bearings (B2), it is also easy to ensure the rigidity of the support structure of the transmission gear (91) and the output gear (92).

[0111] Further, the reciprocating internal combustion engine (10) uses the combination of the planetary gear mechanism (1), the crank member (2), and the piston member (8) as a reciprocating unit (5), includes a pair of the reciprocating units (5), the transmission mechanism (9) includes a pair of the transmission gears (91), one of the pair of the transmission gears (91) is a first transmission gear (91a) that rotates integrally with the carrier (CR(CR1)) of one (5A) of the pair of the reciprocating units (5), the other of the pair of the transmission gears (91) is a second transmission gear (91b) that rotates integrally with the carrier (CR(CR2)) of the other (5B) of the pair of the reciprocating units (5), the output gear (92) meshes with both the first transmission gear (91a) and the second transmission gear (91b), and it is preferable that the output axis center (X4) is arranged at a position different from a line (B) connecting the carrier axis centers (X1(X11,X12)) of the pair of the reciprocating units (5) in an axial view along the axial direction (L).

[0112] According to this configuration, compared with a configuration in which the output axis center (X4) is arranged on a line connecting the carrier axis centers (X1(X11,X12)) of the planetary gear mechanisms (1) of the pair of the reciprocating units (5), the distance between the carrier axis centers (X1(X11,X12)) of the pair of the reciprocating units (5) can be arranged closer. Therefore, it is easy to reduce the size of the reciprocating internal combustion engine (10) provided with the pair of the reciprocating units (5).

[0113] Further, the reciprocating internal combustion engine (10) includes a pair of the reciprocating units (5) arranged side by side in the axial direction (L), with the combination of the planetary gear mechanism (1), the crank member (2), and the piston member (8) as the reciprocating unit (5). The transmission mechanism (9) includes a pair of the transmission gears (91) and a pair of the output gears (92). One of the pair of the transmission gears (91) is a first transmission gear (91a) that rotates integrally with the carrier (CR(CR1)) of one (5A) of the pair of the reciprocating units (5). The other of the pair of the transmission gears (91) is a second transmission gear (91b) that rotates integrally with the carrier (CR(CR2)) of the other (5B) of the pair of the reciprocating units (5). One of the pair of the output gears (92) is a first output gear (92a) that meshes with the first transmission gear (91a). The other of the pair of the output gears (92) is a second output gear (92b) that meshes with the second transmission gear (91b). It is preferable that the first output gear (92a) and the second output gear (92b) are arranged side by side in the axial direction (L) on the output axis (X4) and are connected so as to rotate integrally with the output member (4).

[0114] According to this configuration, in the configuration where the piston members (8) are arranged in series, a pair of the output gears (92(92a, 92b)) arranged side by side in the axial direction (L) can be easily connected by the output member (4). Therefore, it is easy to reduce the size of the reciprocating internal combustion engine (10) in which the piston members (8) are arranged in series.

[0115] Further, the reciprocating internal combustion engine (10) includes a transmission gear (91) that rotates integrally with the carrier (CR) and an output gear (92) that meshes with the transmission gear (91) and rotates integrally with the output member (4) in the transmission mechanism (9). The output member (4) is rotatably supported about an output axis (X4) parallel to the carrier axis (X1) and includes a first counter gear (71) that rotates integrally with the output member (4). Further, a counter shaft (7) rotatably supported about a counter axis (X5) parallel to the carrier axis (X1), and a second counter gear (72) that meshes with the first counter gear (71) and rotates integrally with the counter shaft (7) are provided, and a counter mechanism is provided. The direction in which the piston body (82) reciprocates is defined as the reciprocating direction (I), the direction orthogonal to the reciprocating direction (I) and the axial direction (L) is defined as the width direction (H), one side in the width direction (H) is defined as the first width side (H1), and the other side is defined as the second width side (H2). In a view in the reciprocating direction (I), an axis along the reciprocating direction (I) passing through the center of the piston body (82) is defined as the reciprocating drive axis (Y). The output axis (X4) is disposed on the first width side (H1) and the counter axis (X5) is disposed on the second width side (H2) with the reciprocating drive axis (Y) therebetween. The first counter gear (71) and the second counter gear (72) are preferably counterweight-integrated gears each having a counterweight (70) integrally provided on the gear.

[0116] In a reciprocating internal combustion engine (10), it is preferable to reduce vibrations generated along with the reciprocating motion. For example, in a configuration where the output axis center (X4) is positioned on the reciprocating drive shaft (Y) and the output member (4) is arranged, vibrations in the direction along the reciprocating drive shaft (Y) are easily suppressed, but vibrations in the width direction (H) orthogonal to the reciprocating drive shaft (Y) and the axial direction (L) tend to remain. According to this configuration, with the reciprocating drive shaft (Y) interposed therebetween, the output axis center (X4) and the counter axis center (X5) are arranged separately on both sides in the width direction (H). A first counter gear (71) arranged on the output axis center (X4) meshes with a second counter gear (72) arranged on the counter axis center (X5), and both counter gears are provided with counterweights (70). By the movement of the center of gravity along the reciprocating drive shaft (Y) between the counterweight (73(70)) on the output axis center (X4) and the counterweight (74(70)) on the counter axis center (X5), vibrations in the direction along the reciprocating drive shaft (Y) can be reduced. Also, since the counterweight (73(70)) on the output axis center (X4) and the counterweight (74(70)) on the counter axis center (X5) are arranged separately in the width direction (H), vibrations in the width direction (H) are also easily offset, and the vibrations can be reduced.

[0117] Further, the reciprocating internal combustion engine (10) preferably includes a first counterweight (75) that rotates integrally with the output member (4) and a second counterweight (76) that rotates integrally with the counter shaft (7) independently of the first counterweight (75). The first counter gear (71) and the first counterweight (75) are arranged separately on both sides in the axial direction (L) with respect to the reciprocating drive shaft (Y) and the output gear (92), and the second counter gear (72) and the second counterweight (76) are arranged separately on both sides in the axial direction (L) with respect to the reciprocating drive shaft (Y).

[0118] According to this configuration, in addition to the first counter gear (71) and the second counter gear (72) which are counterweight integrated gears, the first counterweight (75) and the second counterweight (76) can appropriately reduce the vibration in the width direction (H). Further, the first counter gear (71) provided with the counterweight (70) divided on both sides in the axial direction (L) with the reciprocating drive shaft (Y) interposed therebetween and the first counterweight (75) are arranged, and the second counter gear (72) provided with the counterweight (70) divided on both sides in the axial direction (L) with the reciprocating drive shaft (Y) interposed therebetween and the second counterweight (76) are arranged, so that it is easy to achieve weight balance in the axial direction (L), and the vibration in the axial direction (L) can also be suppressed.

[0119] Further, the reciprocating internal combustion engine (10) includes a transmission gear (91) that rotates integrally with the carrier (CR) and an output gear (92) that meshes with the transmission gear (91) and rotates integrally with the output member (4) in the transmission mechanism (9). The output member (4) is rotatably supported around an output axis (X4) parallel to the carrier axis (X1), and further includes a counter shaft (7) rotatably supported around a counter axis (X5) parallel to the carrier axis (X1), and a counter gear (93) that meshes with the transmission gear (91) and rotates integrally with the counter shaft (7). The transmission mechanism (9) is preferably provided with a counter mechanism. It is preferable that the transmission gear (91), the output gear (92), and the counter gear (93) are each a counterweight integrated gear in which a counterweight (70) is integrally provided on the gear.

[0120] According to this configuration, the vibration generated by the reciprocating motion of the piston body 82 and the rotation of the crank member (2) can be appropriately reduced by the movement of the center of gravity of the transmission gear (91), the output gear (92), and the counter gear (93) which are counterweight integrated gears along the reciprocating direction (I). In addition, since the counter gear (93) meshes with the transmission gear (91), the counter gear (93) can be arranged at a position separated from the output gear (92). Therefore, the degree of freedom in arranging the output member (4) and the counter shaft (7) is high, and it is easy to increase the degree of freedom in the overall shape.

[0121] Further, in the reciprocating internal combustion engine (10), the direction in which the piston body (82) reciprocates is defined as the reciprocating direction (I), the direction orthogonal to the reciprocating direction (I) and the axial direction (L) is defined as the width direction (H), one side in the width direction (H) is defined as the first width side (H1), the other side is defined as the second width side (H2), the output axis center (X4) is on the first width side (H1) with respect to the carrier axis center (X1), and is disposed at the same position as the carrier axis center (X1) in the reciprocating direction (I) or at a position on the piston body (82) side with respect to the carrier axis center (X1) in the reciprocating direction (I), the counter axis center (X5) is on the second width side (H2) with respect to the carrier axis center (X1), and is disposed at the same position as the carrier axis center (X1) in the reciprocating direction (I) or at a position on the piston body (82) side with respect to the carrier axis center (X1) in the reciprocating direction (I), and it is preferable that the transmission gear (91), the output gear (92), and the counter gear (93) are disposed so as to be located between the first connecting portion (85) and the second connecting portion (86) in the axial direction (L).

[0122] According to this configuration, since the output axis center (X4) and the counter axis center (X5) are at the same position as the carrier axis center (X1) in the reciprocating direction (I) or on the piston body (82) side with respect to the carrier axis center (X1), it is easier to suppress the size of the transmission mechanism (9) in the reciprocating direction (I) as compared with the case where the output axis center (X4) and the counter axis center (X5) are on the side opposite to the piston body (82) side with respect to the carrier axis center (X1). In addition, since the transmission gear (91), the output gear (92), and the counter gear (93) are disposed between the first connecting portion (85) and the second connecting portion (86) in the axial direction (L), it is easier to suppress the size of the transmission mechanism (9) in the axial direction (L), and it is easier to ensure the rigidity of the support structure of each gear.

[0123] Further, the reciprocating internal combustion engine (10) has the transmission gear (91), the output gear (92), and the counter gear (93) meshing with each other so as to rotate at the same speed. The counterweight (102(70)) of the output gear (92) is provided on the output gear (92) such that the magnitude of the moment about the output axis (X4) is the same as the magnitude of the moment about the counter axis (X5) by the counterweight (103(70)) of the counter gear (93). The counterweight (101(70)) of the transmission gear (91) is provided on the transmission gear (91) such that the moment about the carrier axis (X1) is opposite to the sum of the moment about the output axis (X4) by the counterweight (102(70)) of the output gear (92) and the moment about the counter axis (X5) by the counterweight (103(70)) of the counter gear (93), and the magnitudes are the same. In a state where the piston body (82) is located at each of the top dead center and the bottom dead center, the resultant force of the centrifugal forces acting on the counterweight (101(70)) of the transmission gear (91), the counterweight (102(70)) of the output gear (92), and the counterweight (103(70)) of the counter gear (93) is opposite to the resultant force of the inertial force acting on the piston member (8) and the centrifugal force acting on the crank member (2), and is preferably set to have the same magnitude.

[0124] According to this configuration, vibrations generated along with the reciprocating motions of the piston member (8) and the crank member (2) can be effectively reduced.

[0125] Further, it is preferable that the carrier axis (X1) of the reciprocating internal combustion engine (10) is arranged at a position intersecting the reciprocating drive shaft (Y).

[0126] According to this configuration, it is easy to cancel out vibrations in the width direction H of the reciprocating internal combustion engine (10).

[0127] Further, in the reciprocating internal combustion engine (10), the transmission mechanism (9) includes a transmission gear (91) that rotates integrally with the carrier (CR), a first countershaft (C11) rotatably supported around a first countershaft axis (X51) parallel to the carrier axis (X1), and a first counter gear (C12) that meshes with the transmission gear (91) and rotates integrally with the first countershaft (C11). The first counter mechanism (C1) includes a second countershaft (C21) rotatably supported around a second countershaft axis (X52) parallel to the carrier axis (X1), and a second counter gear (C22) that meshes with the transmission gear (91) and rotates integrally with the second countershaft (C21). The second counter mechanism (C2) includes a gear that rotates integrally with the first countershaft (C11), and an output gear (CK) that meshes with at least one of the gears that rotate integrally with the second countershaft (C21) and rotates integrally with the output member (4). The output member (4) is rotatably supported around an output axis (X4) parallel to the carrier axis (X1), and it is preferable that the moment of inertia of the member rotating around the carrier axis (X1) and the member rotating around the output axis (X4) cancels out the moment of inertia of the member rotating around the first countershaft axis (X51) and the member rotating around the second countershaft axis (X52).

[0128] According to this configuration, vibrations caused by torque fluctuations due to the combustion cycle or the like of the reciprocating internal combustion engine (10) can be effectively reduced.

[0129] Further, in the reciprocating internal combustion engine (10), a generator (MG) is drivingly connected to the output member (4), and it is preferable that the gear ratio of the output gear (CK) and the gear meshing with the output gear (CK) is set such that the rotational speed of the output member (4) is higher than the rotational speeds of the first countershaft (C11) and the second countershaft (C21).

[0130] According to this configuration, it is easy to increase the rotational speed of the generator (MG) with respect to the rotational speed of the carrier (CR) of the reciprocating internal combustion engine (10). Therefore, it is easy to reduce the size and improve the efficiency of the generator (MG).

Explanation of Signs

[0131] 1: Planetary gear mechanism, 2: Crank member, 4: Output member, 5: Reciprocating unit, 7: Countershaft, 8: Piston member, 9: Transmission mechanism, 10: Reciprocating internal combustion engine, 21: First crank part, 22: Second crank part, 70: Counterweight, 71: First counter gear, 72: Second counter gear, 75: First counterweight, 76: Second counterweight, 82: Piston body, 83: Connecting rod (pair of connecting parts), 85: First connecting part, 86: Second connecting part, 87: Intermediate connecting part, 88: Axial connecting part, 89: Reciprocating direction connecting part, 91: Transmission gear, 91a: First transmission gear, 91b: Second transmission gear, 91c: Third transmission gear (first transmission gear), 91d: Fourth transmission gear (second transmission gear), 92: Output gear, 92a: First output gear, 92b: Second output gear, B1: Planetary bearing, B2: Carrier bearing, CR: Carrier, C1: First counter mechanism, C2: Second counter mechanism, CK: Output gear, C11: First countershaft, C12: First counter gear, C21: Second countershaft, C22: Second counter gear, H: Width direction, H1: First side in the width direction, H2: Second side in the width direction, I: Reciprocating direction, L: Axial direction, MG: Generator, PG: Planetary gear, R: Radial direction, RG: Ring gear, Rp: Planetary radial direction, X1: Carrier axis center, X2: Planetary axis center, X3: Input axis center, X4: Output axis center, X5: Countershaft axis center, X51: First countershaft axis center, X52: Second countershaft axis center, Y: Reciprocating drive shaft, d23: Axial distance, d82: Piston ring diameter (axial dimension of the piston body), d88: Rod width (axial dimension of the axial connecting part), r1: Ring radius (radius of the ring gear), r2: Planetary radius (radius of the planetary gear)

Claims

1. a planetary gear mechanism including a ring gear which is an internal gear, a carrier supported rotatably relative to the ring gear, and a planetary gear supported rotatably relative to the carrier and meshing with the ring gear; A direction along a carrier axis, which is a rotation axis of the carrier, is defined as an axial direction, a direction perpendicular to the carrier axis is defined as a radial direction, and a direction perpendicular to a planet axis, which is a rotation axis of the planet gear, is defined as a planet radial direction, a crank member connected to the planetary gear so as to rotate integrally with the planetary gear; a piston member connected to the crank member so as to be relatively rotatable about an input axis set at a position spaced apart from the planet axis in the planet radial direction; a transmission mechanism that transmits the rotation of the carrier to an output member, the radius of the ring gear is twice the radius of the planetary gears; a pair of planetary bearings are arranged on either side of the planetary gear in the axial direction to rotatably support the planetary gear relative to the carrier; a pair of carrier bearings are arranged on both sides of the ring gear in the axial direction, the pair supporting the carrier rotatably relative to the ring gear; the crank member includes a pair of crank portions, that is, a first crank portion and a second crank portion, disposed separately on both sides of the carrier in the axial direction, the piston member includes a piston body and a pair of connecting portions, a first connecting portion and a second connecting portion, which are connected to the piston body and are disposed separately on both sides of the carrier in the axial direction, The first crank portion and the second crank portion are arranged to extend in the planetary radial direction, the first connecting portion is connected to the first crank portion so as to be relatively rotatable about the input shaft center, The second connecting portion is connected to the second crank portion so as to be relatively rotatable about the input shaft center.

2. The radius of the planetary gear is equal to the distance between the planetary shaft center and the input shaft center in the planetary radial direction, The reciprocating internal combustion engine according to claim 1 , wherein the first connecting portion and the second connecting portion are integrally connected to the piston body.

3. The direction in which the piston body reciprocates is defined as a reciprocating direction, the first connecting portion and the second connecting portion are integrally connected to the piston body via an intermediate connecting portion, the intermediate connecting portion includes an axial connecting portion that connects the first connecting portion and the second connecting portion in the axial direction, and a reciprocating direction connecting portion that connects the axial connecting portion and the piston body in the reciprocating direction, an axial dimension of the axial coupling portion is greater than an axial dimension of the piston body, 3. The reciprocating internal combustion engine according to claim 2, wherein the reciprocating direction connecting portion is formed so that a cross section perpendicular to the reciprocating direction is smaller than that of the piston body.

4. the transmission mechanism includes a transmission gear that rotates integrally with the carrier, and an output gear that meshes with the transmission gear and rotates integrally with the output member, the output gear and the output member are supported rotatably about an output axis parallel to the carrier axis, 4. The reciprocating internal combustion engine according to claim 1, wherein the transmission gear and the output gear are disposed axially between the pair of carrier bearings.

5. a set of the planetary gear mechanism, the crank member, and the piston member as a reciprocating unit, A pair of the reciprocating units is provided, The transmission mechanism includes a pair of the transmission gears, one of the pair of transmission gears is a first transmission gear that rotates integrally with the carrier of one of the pair of reciprocating units, the other of the pair of transmission gears is a second transmission gear that rotates integrally with the other of the pair of reciprocating units, the output gear meshes with both the first transmission gear and the second transmission gear, 5. The reciprocating internal combustion engine according to claim 4, wherein, as viewed in the axial direction along the axial direction, the output shaft center is disposed at a position different from a line connecting the carrier shaft centers of the pair of reciprocating units.

6. a set of the planetary gear mechanism, the crank member, and the piston member as a reciprocating unit, a pair of the reciprocating units arranged side by side in the axial direction, the transmission mechanism includes a pair of the transmission gears and a pair of the output gears, one of the pair of transmission gears is a first transmission gear that rotates integrally with the carrier of one of the pair of reciprocating units, the other of the pair of transmission gears is a second transmission gear that rotates integrally with the other of the pair of reciprocating units, one of the pair of output gears is a first output gear that meshes with the first transmission gear, the other of the pair of output gears is a second output gear that meshes with the second transmission gear, 5. The reciprocating internal combustion engine according to claim 4, wherein the first output gear and the second output gear are arranged side by side in the axial direction on the output shaft center, and each is connected to the output member so as to rotate integrally with the output member.

7. the transmission mechanism includes a transmission gear that rotates integrally with the carrier, and an output gear that meshes with the transmission gear and rotates integrally with the output member, the output member includes a first counter gear that is supported rotatably about an output axis parallel to the carrier axis and rotates integrally with the output member, a counter mechanism including a counter shaft supported rotatably about a counter axis parallel to the carrier axis, and a second counter gear meshing with the first counter gear and rotating integrally with the counter shaft, The direction in which the piston body reciprocates is defined as a reciprocating direction, A direction perpendicular to the reciprocating direction and the axial direction is defined as a width direction, one side of the width direction is defined as a width direction first side, and the other side is defined as a width direction second side, An axis passing through the center of the piston body as viewed in the reciprocating direction and aligned along the reciprocating direction is defined as a reciprocating drive axis, The output shaft is disposed on a first side in the width direction with the reciprocating drive shaft interposed therebetween, and the counter shaft is disposed on a second side in the width direction, 4. The reciprocating internal combustion engine according to claim 1, wherein the first counter gear and the second counter gear are integral gears each having a counterweight provided integrally with the gear.

8. a first counterweight that rotates integrally with the output member; and a second counterweight that rotates integrally with the counter shaft independently of the first counterweight, the first counter gear and the first counter weight are arranged separately on both sides of the reciprocating drive shaft and the output gear in the axial direction, 8. The reciprocating internal combustion engine according to claim 7, wherein the second counter gear and the second counter weight are disposed separately on both sides in the axial direction of the reciprocating drive shaft.

9. the transmission mechanism includes a transmission gear that rotates integrally with the carrier, and an output gear that meshes with the transmission gear and rotates integrally with the output member, the output member is supported rotatably about an output axis parallel to the carrier axis, a counter mechanism including a counter shaft supported rotatably about a counter axis parallel to the carrier axis, and a counter gear meshing with the transmission gear and rotating integrally with the counter shaft, 4. The reciprocating internal combustion engine according to claim 1, wherein the transmission gear, the output gear, and the counter gear are each a counterweight-integrated gear in which a counterweight is provided integrally with the gear.

10. The direction in which the piston body reciprocates is defined as a reciprocating direction, A direction perpendicular to the reciprocating direction and the axial direction is defined as a width direction, one side of the width direction is defined as a width direction first side, and the other side is defined as a width direction second side, the output shaft center is disposed on the first side in the width direction with respect to the carrier shaft center, and at the same position as the carrier shaft center in the reciprocating direction or at a position on the piston body side with respect to the carrier shaft center in the reciprocating direction, the counter shaft is disposed on the second width direction side with respect to the carrier shaft, and at the same position as the carrier shaft in the reciprocating direction or at a position on the piston body side with respect to the carrier shaft in the reciprocating direction, 10. The reciprocating internal combustion engine according to claim 9, wherein the transmission gear, the output gear, and the counter gear are disposed so as to be located between the first connecting portion and the second connecting portion in the axial direction.

11. The transmission mechanism includes: a transmission gear that rotates integrally with the carrier; a first counter mechanism including a first counter shaft supported rotatably about a first counter axis parallel to the carrier axis, and a first counter gear meshing with the transmission gear and rotating integrally with the first counter shaft; a second counter mechanism including a second counter shaft supported rotatably about a second counter axis parallel to the carrier axis, and a second counter gear meshing with the transmission gear and rotating integrally with the second counter shaft; an output gear that meshes with at least one of the gear that rotates integrally with the first countershaft and the gear that rotates integrally with the second countershaft and that rotates integrally with the output member; Equipped with the output member is supported rotatably about an output axis parallel to the carrier axis, 4. The reciprocating internal combustion engine according to claim 1, wherein a moment of inertia of a member rotating about the carrier axis and a member rotating about the output axis and a moment of inertia of a member rotating about the first counter axis and a member rotating about the second counter axis are configured to cancel each other out.

12. A generator is drivingly connected to the output member, 12. The reciprocating internal combustion engine according to claim 11, wherein a gear ratio of the output gear and the gear meshing with the output gear is set so that a rotational speed of the output member is higher than a rotational speed of the first countershaft and the second countershaft.

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