Reciprocating internal combustion engine

Abstract

To provide a reciprocating internal combustion engine capable of appropriately reducing vibrations in a linear-to-rotary motion conversion mechanism converting linear motion of a piston into rotary motion, even when the piston is increased in size.SOLUTION: A reciprocating internal combustion engine 10 comprises: a planetary gear mechanism 1; a crank member 2; a piston member 8; a case 6 which houses a transmission mechanism 9 and has a ring gear RG fixed thereto; a first rack gear 71 fixed to the piston member 8; a pinion gear 73 which has a rotational shaft center Xp fixed relative to the case 6 and is engaged with the first rack gear 71; and a counterweight W which has a second rack gear 72 arranged parallel to the first rack gear 71 and engaged with the pinion gear 73.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 connecting rod (3) connected to a piston (15) into the rotational motion of an output member (10) as a power conversion device applicable to a reciprocating internal combustion engine (the reference numerals in parentheses in the background art are those of the cited document). The planetary gear mechanism (4) includes a ring gear (20) that 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 that rotatably supports 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 such a power conversion device (crank device (1)), a counterweight is often arranged to reduce the vibration caused by the reciprocating motion of the connecting rod (3). Also in the above-described crank device (1), as shown in FIG. 5 of the document, counterweights (30, 31) are provided on each of the planetary gear (21) and the crank arm (11) that functions as a carrier. However, in this crank device (1), since the counterweights (30, 31) are arranged inside the ring gear (20), the arrangement space for the counterweights is limited, and for example, when the piston becomes large, there is a risk that vibration reduction cannot be sufficiently achieved.

[0005] In view of the above background, even if the piston is enlarged, it is desirable to provide a reciprocating internal combustion engine capable of appropriately reducing vibration in a linear motion conversion mechanism that converts the linear motion of the piston into a rotational motion.

Means for Solving the Problem

[0006] The reciprocating internal combustion engine in view of the above includes a planetary gear mechanism including a ring gear that is an internal 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, a piston member relatively rotatably connected around an input axis set at a position separated from the planetary axis in the planetary radial direction with respect to the crank member, where the planetary radial direction is a direction orthogonal to the planetary axis that is the rotation axis of the planetary gear, a transmission mechanism that transmits the rotation of the carrier to an output member, and a case that houses the planetary gear mechanism, the crank member, the piston member, and the transmission mechanism and in which the ring gear is fixed. The radius of the ring gear is twice the radius of the planetary gear, the radius of the planetary gear is the same as the distance in the planetary radial direction between the planetary axis and the input axis, a first rack gear fixed to the piston member, a pinion gear having a rotation axis fixed to the case and meshing with the first rack gear, and a counterweight including a second rack gear arranged in parallel with the first rack gear and meshing with the pinion gear.

[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, since the input axis reciprocates linearly, the entire piston member also reciprocates linearly in the same manner. And, since the counterweight interlocked with the piston member via the first rack gear and the pinion gear fixed to the reciprocating piston member reciprocates in a phase opposite to that of the piston member, the vibration of the reciprocating internal combustion engine can be effectively reduced. Further, since the counterweight is arranged on a member different from the planetary gear, carrier, etc. constituting the planetary gear mechanism of the direct-acting conversion mechanism, it is easy to provide a counterweight according to the weight of the piston member. That is, according to this configuration, even if the piston is enlarged, a reciprocating internal combustion engine capable of appropriately reducing vibration in a direct-acting conversion mechanism that converts the linear motion of the piston into rotational motion can be provided.

[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]

Figure 1

Figure 2

Figure 3

Embodiments 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 cross-sectional view schematically showing a first example of a reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 includes a power conversion mechanism including a planetary gear mechanism 1, a crank member 2, and a piston member 8, a transmission mechanism 9, and a case 6. The case 6 houses the planetary gear mechanism 1, the crank member 2, the piston member 8, and the transmission mechanism 9.

[0011] As will be described later in detail, the planetary gear mechanism 1 includes a ring gear RG that is an internal gear, 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. The ring gear RG is fixed to the case 6. 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 set at a position spaced apart from the planetary axis X2, which is the rotation axis of the planetary gear PG, in the planetary radial direction Rp orthogonal to the planetary axis X2. 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 non-rotatably fixed to non-rotating members such as the cylinder 81 and the case 6. 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 bearings B1 are divided on both sides in the axial direction L with respect to the planetary gear PG, and a pair of them are arranged to rotatably support the planetary gear PG with respect to the carrier CR. 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 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 bearings B2 are divided on both sides in the axial direction L with respect to the ring gear RG, and a pair of them are arranged to rotatably support the carrier CR with respect to the ring gear RG. The carrier bearing B2 is, for example, a ball bearing.

[0016] On each of the first axial side L1 and the second axial side L2, the carrier bearing B2 is arranged so as to overlap the movement locus of the planetary bearing B1 accompanying the revolution of the planetary gear PG in a radial view along the radial direction R. Thereby, it is easy to reduce the dimension in the axial direction L of the reciprocating internal combustion engine 10.

[0017] 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. Also in the relationship between the carrier bearing B2 and the planetary bearing B1, it is not limited to a configuration in which the whole of one of the carrier bearing B2 and the planetary bearing B1 overlaps with the other bearing, and a part of each other may overlap.

[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) 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 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 by the first crank portion 21 and the first connecting portion 85 being connected to be relatively rotatable about the input axis X3, and the second crank portion 22 and the second connecting portion 86 being connected to be relatively rotatable about the input axis X3. Crank bearings B4 are respectively arranged 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 (planetary radial direction Rp).

[0021] As still illustrated in FIG. 1, in the present embodiment, an axially-shaped input member (e.g., a crank pin) disposed on the input axis X3 is provided integrally with the crank member 2, and an example is illustrated in which the input member and the connecting rod are connected so as to be relatively rotatable, but the present invention is not limited to this configuration. For example, an axially-shaped input member may be provided integrally with the connecting rod on the input axis X3, and the input member and the crank member 2 may be connected so as to be relatively rotatable. Further, a form in which the input member is provided separately from the crank member 2 and the connecting rod is not precluded. Further, a form in which the input member is not an axially-shaped 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 reciprocates with reference to the carrier axis X1, and along with this reciprocating motion, the carrier CR rotates about the carrier axis X1. Note that the crank member 2 shown by the solid line in FIG. 1 shows a state in which 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 in which the piston body 82 is located at the bottom dead center of the reciprocating motion.

[0023] In the present 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) becomes linear along the axial direction L as viewed in the axial direction 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".

[0024] In addition, in the present embodiment, an example is shown in which the piston body 82 and the connecting rod (the first connecting portion 85 and the second connecting portion 86) are configured by separate members and are fastened and integrated by bolts. Specifically, 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 dimension of the reciprocating connecting portion 89 in the direction orthogonal to the reciprocating direction I is smaller than the diameter of the piston body 82 and the inner diameter of the cylinder 81 in the direction orthogonal to the reciprocating direction I. Therefore, as shown in FIG. 1, a space is also formed between the piston body 82 and the axial connecting portion 88.

[0025] Here, an example is shown in which the axial connecting portion 88 and the reciprocating connecting portion 89 are fastened and fixed by a fastening member such as a bolt, but they may be integrated by welding, for example. Naturally, it is not limited to this form, and the piston body 82 and the connecting rod may be integrally formed by the same member.

[0026] The output member 4 is drivingly connected to the carrier CR via a 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 around 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 bearing B3 is, for example, a ball bearing. Further, the transmission gear 91 and the output gear 92 are arranged between the axial directions L of a pair of carrier bearings B2.

[0027] Here, the form in which the output member 4 is a shaft-like member is illustrated, but the present invention is not limited to this form. For example, as will be described later with reference to FIGS. 2 and 3, when the carrier CR is connected to the rotor 32 of the rotating electric machine 3 that functions as a generator, the rotor of the rotating electric machine 3 may be the output member 4. Further, a configuration in which the transmission gear 91 or the output gear 92 serves as the output member 4 is not obstructive either. Here, the form in which the transmission mechanism 9 is a gear mechanism including the transmission gear 91 and the output gear 92 is illustrated, but the transmission mechanism 9 is not limited to a gear mechanism. For example, as will be described later with reference to FIG. 2, the rotor support member 95 that connects the carrier CR and the rotor 32 may be the transmission mechanism 9.

[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 with respect to the left and right 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 and the pair of crank members 2 of the piston member 8 are arranged separately on both sides of the carrier CR in the axial direction L, and each is connected so as to be relatively rotatable around the input axis X3. Therefore, it is easy to ensure the rigidity of the support structure of the piston member 8, and it is also easy to stabilize the operations of the piston member 8 and the crank member 2.

[0029] In such a power conversion mechanism, a counterweight is often arranged to reduce the vibration caused by the reciprocating motion of the piston member 8 and the connecting rod. As in the present embodiment in which the piston body 82 and the connecting rod (the first connecting portion 85 and the second connecting portion 86) formed of separate members are integrated, when the piston member 8 becomes large, vibration reduction is more required.

[0030] The reciprocating internal combustion engine 10 of the present embodiment includes a first rack gear 71 fixed to the piston member 8, a pinion gear 73 having a rotation axis center (pinion axis Xp) fixed to the case 6 and meshing with the first rack gear 71, and a counterweight W having a second rack gear 72 arranged in parallel with the first rack gear 71 and meshing with the pinion gear 73. That is, the reciprocating internal combustion engine 10 of the present embodiment includes a rack & pinion mechanism that acts on the vibration damping function by the counterweight W. Note that the pinion gear 73 is not limited in diameter and shape as long as it is a gear that meshes with the rack gear. Further, in the present embodiment, a form in which the first rack gear 71 and the second rack gear 72 are parallel is illustrated, but the positional relationship between the two may be inclined slightly (within about 15 degrees).

[0031] In the present embodiment, a form in which the first rack gear 71 is integrally formed by the same member as the connecting rod (first connecting portion 85, second connecting portion 86) is illustrated. However, the first rack gear 71 may be formed as a separate member from the connecting rod and fixed to the connecting rod by fastening with a fastening member, welding, or the like. Further, in the present embodiment, a form in which the second rack gear 72 is integrally formed with the counterweight W is illustrated, but the second rack gear 72 and the counterweight W may be configured by separate members and integrated by fastening, welding, or the like.

[0032] Note that in the present embodiment, the counterweight W is a cylindrical member that passes through the center of the piston member 8 when viewed in the direction along the reciprocating direction I and is arranged coaxially with the reciprocating axis Xi parallel to the reciprocating direction I. Here, a cylindrical member is illustrated, but the cylindrical member may have a square cross section or a rectangular tube shape including polygons other than a square. Since the planetary gear mechanism 1 can be arranged using the space inside the counterweight W, it is easy to reduce the size of the reciprocating internal combustion engine 10.

[0033] The counterweight W may be arranged with a gap between it and the case 6 in order to reduce the loss of the reciprocating motion of the piston member 8, but in the present embodiment, it is in contact with the case 6. That is, in the present embodiment, the counterweight W is in contact with the inner surface 6a of the case 6 at the contact portion 79 and is slidable on the inner surface 6a of the case 6. Since the cylindrical counterweight W is integrally formed in the circumferential direction, it is easy to simplify the mechanism for supporting and guiding the counterweight W in the radial direction (here, the direction perpendicular to the reciprocating axis Xi) by the case 6.

[0034] In addition, the mass (here, equivalent to the weight) of the counterweight W includes the mass of the second rack gear 72. The planetary gear mechanism 1, which is a rotating member, is configured to achieve weight balance independently, and it is preferable that the mass of the counterweight W is the same as the sum of the mass of the piston member 8 and the mass of the crank member 2. Here, the mass of the crank member 2 includes the mass of the shaft-like input member (crank pin). In the case of a configuration in which the crank member 2 is extended to both sides in the axial direction L with respect to the planetary axis X2 to achieve weight balance, it is preferable that the mass of the counterweight W is the same as the sum of the mass of the piston member 8 and the mass of the crank pin in the crank member 2.

[0035] The counterweight W interlocked with the piston member 8 via the first rack gear 71 fixed to the piston member 8 that reciprocates linearly and the pinion gear 73 reciprocates in a reverse phase to the piston member 8. Thereby, the vibration of the reciprocating internal combustion engine 10 can be effectively reduced. Further, since the counterweight W is arranged on a member different from the planetary gear PG, the carrier CR, etc. constituting the planetary gear mechanism 1 of the power conversion mechanism, it is easy to provide the counterweight W according to the weight of the piston member 8. That is, the arrangement space of the counterweight W is not easily restricted, and for example, even if the piston member 8 becomes large, it is easy to appropriately reduce the vibration.

[0036] As described above with reference to FIG. 1, in the present embodiment, a pair of first rack gears 71 are fixed to both the first connecting portion 85 and the second connecting portion 86. However, the first rack gear 71 only needs to be fixed to at least one of the first connecting portion 85 and the second connecting portion 86. That is, one first rack gear 71 may be fixed to either the first connecting portion 85 or the second connecting portion 86. In any case, by fixing the first rack gear 71 to the connecting portion that reciprocates integrally with the piston body 82 outside the cylinder 81 in which the piston body 82 reciprocates, it is easy to secure the degree of freedom in the arrangement of the pinion gear 73 and the counterweight W. In addition, since the connecting rod (the first connecting portion 85, the second connecting portion 86) and the member that supports the first rack gear 71 can be shared, the configuration of the reciprocating internal combustion engine 10 can be simplified and weight reduction can be easily achieved.

[0037] In addition, in the form illustrated in FIG. 1, a form is illustrated in which the first rack gear 71 and the second rack gear 72 are arranged on both sides in the axial direction L with respect to the power conversion mechanism including the piston member 8. However, the first rack gear 71 and the second rack gear 72 may be arranged on both sides with the piston member 8 (power conversion mechanism) interposed therebetween in a direction orthogonal to the reciprocating direction I and the axial direction L.

[0038] FIGS. 2 and 3 show a second example of the reciprocating internal combustion engine 10. The reciprocating internal combustion engine 10 of the second example is configured as a power generation device including a rotary electric machine 3 (generator). Since the configuration of the power conversion mechanism including the planetary gear mechanism 1, the crank member 2, and the piston member 8 is the same as that of the reciprocating internal combustion engine 10 of the first example, detailed description thereof is omitted.

[0039] In the reciprocating internal combustion engine 10 of the first example, a form in which the output member 4 is a shaft-like member is illustrated, and a form in which the transmission mechanism 9 is constituted by a transmission gear 91 that rotates integrally with the carrier CR and an output gear 92 that rotates integrally with the output member 4 is illustrated. In the reciprocating internal combustion engine 10 of the second example, the carrier CR is connected to the rotor 32 of the rotary electric machine 3 so as to rotate integrally with the rotor 32. In the second example, a rotor support member 95 that is integrally formed on the carrier CR and connects the carrier CR and the rotor 32 corresponds to the transmission mechanism 9. Further, in the second example, the rotor 32 corresponds to the output member 4.

[0040] The rotary electric machine 3 includes a stator 31 and a rotor 32. The stator 31 is fixed to a rotary electric machine case 30 that is a non-rotating member. The rotor 32 is supported rotatably with respect to the stator 31 inside the radial direction of the stator 31. In the present embodiment, the planetary gear mechanism 1 and the rotary electric machine 3 are arranged coaxially, and the stator 31 and the rotor 32 are arranged on the carrier axis X1.

[0041] As described above, the rotor 32 corresponds to the output member 4, is connected to the carrier CR, and rotates integrally with the carrier CR. In the present embodiment, the rotor 32 is connected to the output member 4 via the rotor support member 95. The rotor support member 95 is formed to extend along the radial direction R. In the present embodiment, the rotor support member 95 is arranged to extend outward in the radial direction R from the carrier CR between the axial directions L of the pair of output bearings B3 and supports the rotor 32 from the inside of the radial direction R. In the present embodiment, a configuration in which the rotor support member 95 is integrally formed with the carrier CR is illustrated, but the rotor support member 95 may be formed as a separate member from the carrier CR and connected to the carrier CR by welding or the like.

[0042] As described above, the reciprocating motion of the piston member 8 is converted into the rotational motion of the carrier CR by the power conversion mechanism. The rotor 32 of the rotary electric machine 3 connected to the carrier CR rotates integrally with the carrier CR, and the rotary electric machine 3 generates electricity by the driving force transmitted to the rotor 32.

[0043] In the first example, the form in which the cylindrical counterweight W is arranged was illustrated. However, in the second example, a plurality of counterweights W are arranged at equal distances from the reciprocating shaft Xi. That is, a plurality of counterweights W can be dispersedly arranged around the reciprocating shaft Xi. As shown in FIG. 2, the counterweight W is provided with a rolling roller 78 that can roll on the inner surface 6a of the case 6. Each of the plurality of counterweights W is guided with respect to the case 6 so as to move along the reciprocating direction I. Incidentally, the counterweight W may be configured to slide on the inner surface 6a of the case 6 without including the rolling roller 78 and having a contact portion 79 as in the first example.

[0044] Also in the second example, the form in which the first rack gear 71 and the second rack gear 72 are arranged on both sides in the axial direction L with respect to the power conversion mechanism including the piston member 8 is illustrated. However, the first rack gear 71 and the second rack gear 72 may be arranged on both sides with the piston member 8 (power conversion mechanism) interposed therebetween in the direction orthogonal to the reciprocating direction I and the axial direction L.

[0045] Hereinafter, the reciprocating internal combustion engine (10) described above will be briefly summarized.

[0046] In one aspect, a reciprocating internal combustion engine (10) includes a planetary gear mechanism (1) having a ring gear (RG) which is an internal gear, 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); 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), where the planetary radial direction (Rp) is a direction orthogonal to the planetary axis (X2) which is the rotation axis of the planetary gear (PG); a transmission mechanism (9) for transmitting the rotation of the carrier (CR) to an output member (4); and a case (6) housing the planetary gear mechanism (1), the crank member (2), the piston member (8), and the transmission mechanism (9) and having the ring gear (RG) fixed thereto. The radius (r1) of the ring gear (RG) is twice the radius (r2) of the planetary gear (PG), and the radius (r2) of the planetary gear (PG) is the same as the distance (d23) in the planetary radial direction (Rp) between the planetary axis (X2) and the input axis (X3). The reciprocating internal combustion engine further includes a first rack gear (71) fixed to the piston member (8), a pinion gear (73) having a rotation axis (Xp) fixed to the case (6) and meshing with the first rack gear (71), and a counterweight (W) having a second rack gear (72) arranged in parallel with the first rack gear (71) and meshing with the pinion gear (73).

[0047] According to this configuration, the reciprocating motion of the piston member (8) can be converted into rotational motion of the output member (4) and output. Further, since the input axis (X3) reciprocates linearly, the entire piston member (8) also reciprocates linearly in the same manner. Then, the counterweight (W) interlocked with the piston member (8) via the first rack gear (71) and the pinion gear (73) fixed to the reciprocating piston member (8) reciprocates in a phase opposite to that of the piston member (8), so that the vibration of the reciprocating internal combustion engine (10) can be effectively reduced. Further, since the counterweight (W) is arranged on a member different from the planetary gear (PG), the carrier (CR), etc. constituting the planetary gear mechanism (1) of the direct-acting conversion mechanism, it is easy to provide a counterweight (W) corresponding to the weight of the piston member (8). That is, according to this configuration, even if the piston is enlarged, a reciprocating internal combustion engine (10) capable of appropriately reducing vibration in a direct-acting conversion mechanism that converts the linear motion of the piston into rotational motion can be provided.

[0048] Further, in the reciprocating internal combustion engine (10), with the direction along the carrier axis (X1) which is the rotation axis of the carrier (CR) as the axial direction (L), the crank member (2) includes a first crank part (21) and a second crank part (22) which are a pair of crank parts arranged separately 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 part (85) and a second connecting part (86) which are a pair of connecting parts integrally connected to the piston body (82) and arranged separately on both sides of the carrier (CR) in the axial direction (L). The first crank part (21) and the second crank part (22) are arranged to extend in the planetary radial direction (Rp). The first connecting part (85) is connected to the first crank part (21) so as to be relatively rotatable around the input axis (X3), and the second connecting part (86) is connected to the second crank part (22) so as to be relatively rotatable around the input axis (X3). It is preferable that the first rack gear (71) is fixed to at least one of the first connecting part (85) and the second connecting part (86).

[0049] According to this configuration, a first rack gear (71) is fixed to a connecting portion that reciprocates integrally with the piston body (82) outside the cylinder (81) in which the piston body (82) reciprocates. Therefore, it is easy to secure the degree of freedom in arranging the pinion gear (73) and the counterweight (W). Further, since the connecting portion and the member that supports the first rack gear (71) can be shared, the configuration of the reciprocating internal combustion engine (10) can be simplified and weight reduction can be easily achieved.

[0050] Further, in the reciprocating internal combustion engine (10), the direction in which the piston member (8) reciprocates is defined as the reciprocating direction (I), and a shaft passing through the center of the piston member (8) in a view in the reciprocating direction along the reciprocating direction (I) and parallel to the reciprocating direction (I) is defined as the reciprocating axis (Xi). The counterweight (W) is a cylindrical member arranged coaxially with the reciprocating axis (Xi), and it is preferable that the counterweight (W) and the planetary gear mechanism (1) overlap in a view in a direction orthogonal to the reciprocating axis (Xi) at least when the piston member (8) is at the top dead center.

[0051] According to this configuration, since the planetary gear mechanism (1) can be arranged using the space inside the cylindrical counterweight (W), it is easy to reduce the size of the reciprocating internal combustion engine (10). Further, since the counterweight (W) is integrally formed in the circumferential direction, it is easy to simplify the mechanism for guiding while supporting the counterweight (W) in the radial direction orthogonal to the reciprocating axis (Xi).

[0052] Further, in the reciprocating internal combustion engine (10), the direction in which the piston member (8) reciprocates is defined as the reciprocating direction (I), and a shaft passing through the center of the piston member (8) in a view in the reciprocating direction along the reciprocating direction (I) and parallel to the reciprocating direction (I) is defined as the reciprocating axis (Xi). A plurality of the counterweights (W) are arranged at equal distances from the reciprocating axis (Xi), and each of the plurality of counterweights (W) is guided with respect to the case (6) so as to move along the reciprocating direction (I), which is preferable.

[0053] According to this configuration, a plurality of counterweights (W) are dispersedly arranged around the reciprocating shaft (Xi), and each counterweight (W) is guided to move along the reciprocating direction (I). Therefore, the vibration of the reciprocating internal combustion engine (10) can be effectively reduced.

Explanation of Signs

[0054] 1: Planetary gear mechanism, 2: Crank member, 4: Output member, 6: Case, 8: Piston member, 9: Transmission mechanism, 10: Reciprocating internal combustion engine, 21: First crank portion, 22: Second crank portion, 71: First rack gear, 72: Second rack gear, 73: Pinion gear, 82: Piston body, 85: First connecting portion, 86: Second connecting portion, CR: Carrier, I: Reciprocating direction, L: Axial direction, PG: Planetary gear, R: Radial direction, RG: Ring gear, Rp: Planetary radial direction, W: Counterweight, X1: Carrier axis center, X2: Planetary axis center, X3: Input axis center, Xi: Reciprocating shaft, Xp: Pinion axis center (rotation axis center of the pinion gear), d23: Axial distance (planetary radial distance between the planetary axis center and the input axis center), 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 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 so as to rotate integrally with the planetary gear; A piston member relatively rotatably connected around an input axis center set at a position separated from the planetary axis center in the planetary radial direction, with the direction orthogonal to the planetary axis center which is the rotation axis center of the planetary gear being defined as the planetary radial direction, with respect to the crank member; A transmission mechanism for transmitting the rotation of the carrier to an output member; A case that houses the planetary gear mechanism, the crank member, the piston member, and the transmission mechanism, and in which the ring gear is fixed; The radius of the ring gear is twice the radius of the planetary gear; The radius of the planetary gear is the same as the distance in the planetary radial direction between the planetary axis center and the input axis center; A first rack gear fixed to the piston member; A pinion gear having a rotation axis center fixed to the case and meshing with the first rack gear; A reciprocating internal combustion engine including a counterweight having a second rack gear arranged in parallel with the first rack gear and meshing with the pinion gear.

2. With the direction along the carrier axis center which is the rotation axis center of the carrier being defined as the axial direction, The crank member includes a first crank part and a second crank part which are a pair of crank parts arranged separately on both sides of the carrier in the axial direction with respect to the carrier; The piston member includes a piston body, and a first connecting part and a second connecting part which are a pair of connecting parts integrally connected to the piston body and arranged separately on both sides of the carrier in the axial direction with respect to the carrier; The first crank part and the second crank part are arranged so as to extend in the planetary radial direction; The first connecting part is connected to the first crank part so as to be relatively rotatable around the input axis center; The second connecting part is connected to the second crank part so as to be relatively rotatable around the input axis center; The first rack gear is fixed to at least one of the first connecting part and the second connecting part. The reciprocating internal combustion engine according to Claim 1.

3. Taking the direction in which the piston member reciprocates as the reciprocating direction, and taking an axis passing through the center of the piston member in a view in the reciprocating direction along the reciprocating direction and parallel to the reciprocating direction as the reciprocating motion axis, the counterweight is a cylindrical member arranged coaxially with the reciprocating motion axis, The reciprocating internal combustion engine according to claim 1 or 2, wherein at least in a state where the piston member is located at the top dead center, the counterweight and the planetary gear mechanism are arranged so as to overlap in a view in a direction orthogonal to the reciprocating motion axis.

4. Taking the direction in which the piston member reciprocates as the reciprocating direction, and taking an axis passing through the center of the piston member in a view in the reciprocating direction along the reciprocating direction and parallel to the reciprocating direction as the reciprocating motion axis, a plurality of the counterweights are arranged at equal distances from the reciprocating motion axis, The reciprocating internal combustion engine according to claim 1 or 2, wherein each of the plurality of counterweights is guided with respect to the case so as to move along the reciprocating direction.

Images