JP2004092448A - Reciprocating variable compression ratio internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an increase in friction of a bearing part of a crankshaft. <P>SOLUTION: A reciprocating variable compression ratio internal combustion engine has a plurality of bearing caps 16 for a crankshaft rotatably supporting the crankshaft 4 together with a cylinder block 10, a bearing cap 21 for a control shaft rotatably supporting the control shaft 7 together with the plurality of bearing caps 16 for the crankshaft 4 intermittently provided in the axial direction of the crankshaft 4. A beam 26 for the control shaft 7 extending substantially in parallel to a control shaft near a straight line L connecting a rotation center P of the crankshaft 4 and a rotation center Q of the control shaft 7 viewed in the axial direction of the crankshaft 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reciprocating variable compression ratio internal combustion engine.
[0002]
[Prior art]
For example, JP-A-2002-47955 discloses a bearing cap for a crankshaft that rotatably supports a crankshaft together with a cylinder block, and a bearing cap for a control shaft that rotatably supports a control shaft together with the bearing cap for a crankshaft. A reciprocating type variable compression ratio internal combustion engine in which is provided intermittently in the axial direction of a crankshaft is disclosed.
[0003]
[Problems to be solved by the invention]
However, in such a conventional reciprocating variable compression ratio internal combustion engine, since the control cap bearing caps for rotatably supporting the control shaft are not connected to be integral with each other, the combustion load or the piston / When the inertia load of the link part acts, the deformation of the bearing cap for the crankshaft caused by the control shaft load in the opposite direction to the crankshaft load opposes the deformation of the crankshaft deformed by the combustion load on the crankpin or the inertia load. Therefore, there is a problem that the friction of the crank main journal bearing portion formed by the cylinder block and the crankshaft bearing cap deteriorates.
[0004]
Furthermore, since the control shaft itself acts as a part of the structure that suppresses the deformation of the bearing cap for the crankshaft, the rotation of the control shaft causes reluctance, and it is necessary to increase the output of the actuator that controls the rotational position of the control shaft. There was a problem.
[0005]
[Means for Solving the Problems]
Therefore, in the reciprocating variable compression ratio internal combustion engine of the present invention, near the straight line passing through the center of the crankshaft and the center of the control shaft when viewed in the axial direction of the crankshaft, a control shaft beam extending substantially parallel to the control shaft is provided. Is provided.
[0006]
【The invention's effect】
According to the present invention, the deformation of the crankshaft bearing cap due to the control shaft load follows the deformation of the crankshaft due to the crankpin input load, and the crank main journal bearing constituted by the cylinder block and the crankshaft bearing cap It is possible to reduce the one-side contact of the portion, and to reduce the friction of the crank main journal bearing portion.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each of the embodiments described below, common components are denoted by the same reference numerals, and redundant description of the configuration and the function and effect will be omitted as appropriate.
[0008]
FIGS. 1 and 2 show a reciprocating variable compression ratio internal combustion engine according to a first embodiment (corresponding to claims 1 to 4) of the present invention. The reciprocating variable compression ratio internal combustion engine includes an upper link 3 connected to a piston 1 via a piston pin 2, a lower link 6 connected to the upper link 3 and a crankpin 5 of a crankshaft 4, and a crank. It has a control shaft 7 extending substantially parallel to the shaft 4, and a control link 8 having one end swingably connected to the control shaft 7 and the other end connected to the lower link 6.
[0009]
The rotation center Q of the control shaft 7 (which is the same as the rotation center of the main journal 4a of the crankshaft 4 to be described later) (the rotation center of the main journal 7a of the control shaft 7 to be described later) corresponds to the rotation center P of the crankshaft 4. The crankshaft 4 and the control shaft 7 are disposed so that the same definition) is located diagonally below in FIG. That is, the control shaft 7 is located obliquely below the crankshaft 4 in the crankcase.
[0010]
The control shaft 7 is provided with a pin journal 9 rotatably supported by a bearing formed at one end of the control link 8, which is formed intermittently in the axial direction of the crankshaft 4. The rotation center R of the pin journal 9 is eccentric with respect to the rotation center Q of the main journal 7a of the control shaft 7 by a predetermined amount, and the control link 8 is controlled by using the rotation center R as a swing fulcrum (swing center). It swings with respect to the shaft 7.
[0011]
Therefore, when the main journal 7a of the control shaft 7 rotates, the swinging fulcrum position R of the control link 8 changes, and the distance from the crank pin 5 to the piston pin 2 changes accordingly, and the engine compression ratio decreases. It has a changing configuration. The main journal 7a of the control shaft 7 is rotationally driven by a drive source (not shown) such as a motor connected via a worm (not shown) and a worm wheel (not shown). The drive is controlled by a well-known engine control unit or the like according to the engine operating state. Here, 10 in FIG. 1 is a cylinder block, and 11 is a counterweight.
[0012]
Next, a support structure of the crankshaft 4 and the control shaft 7 will be described. The crank main journal bearing portion 15 rotatably supporting the main journal 4a of the crankshaft 4 has a structure in which an upper half is formed on a lower surface of the cylinder block 10 and a lower half is formed on an upper surface of a bearing cap 16 for a crankshaft. ing. The crankshaft bearing caps 16 are intermittently arranged along the axial direction of the crankshaft 4 at both ends of the cylinder row and between the cylinders.
[0013]
The control main journal bearing portion 17 that rotatably supports the main journal 7a of the control shaft 7 has a lower surface 20 of an extension portion 19 whose upper half projects obliquely downward from a base surface 18 of the crankshaft bearing cap 16 integrally. And the lower half is formed on the upper surface of the control shaft bearing cap 21. That is, the crankshaft bearing cap 16 has a substantially L-shaped plate shape. The base surface 18 of the bearing cap 16 for the crankshaft and the lower surface 22 of the bearing cap 21 for the control shaft are located on two planes which are parallel to each other and discontinuous with each other.
[0014]
The crankshaft bearing cap 16 is fastened to the cylinder block 10 from below by bolts 23 and 24 at two places with the crank main journal bearing portion 15 therebetween. The control shaft bearing cap 21 is fastened to the crankshaft bearing cap 16 and the cylinder block 10 from below by bolts 24 and 25 at two locations with the control main journal bearing portion 17 therebetween. That is, the bolt 24 is located between the bolt 23 and the bolt 25 when viewed in the axial direction of the crankshaft 4 (FIG. 1), and is located between the crank main journal bearing 15 and the control main journal bearing 17. I have. The bolt 24 is fastened to the cylinder block 10 through both the crankshaft bearing cap 16 and the control shaft bearing cap 21.
[0015]
When viewed in the axial direction of the crankshaft 4 (FIG. 1), the center of rotation P of the main journal 4a of the crankshaft 4 (center of rotation of the crankshaft 4) and the center of rotation of the main journal 7a of the control shaft 7 (center of rotation of the control shaft 7). A control shaft beam 26 extending substantially parallel to the control shaft 7 is provided in the vicinity of a straight line L connecting Q). More specifically, in the first embodiment, between the main journal 4a of the crankshaft 4 and the main journal 7a of the control shaft 7 when viewed in the axial direction of the crankshaft 4, that is, the lower surface of the control shaft bearing cap 21. On the left side of FIG. 1 in FIG. 1, a control shaft beam 26 is provided.
[0016]
The control shaft beam 26 is fastened to the control shaft bearing cap 21, the crankshaft bearing cap 16 and the cylinder block 10 by the bolts 24 described above. More specifically, the control shaft beam 26 is fixed to the control shaft bearing cap 21 and the crankshaft bearing cap 16 by bolts 24 penetrating between the crankshaft 4 and the control shaft 7 in the axial direction of the crankshaft 4. And the cylinder block 10. In other words, the control shaft beam 26 is fastened to the control shaft bearing cap 21 by the bolt 24 located closer to the crankshaft 4 among the two bolts 24 and 25 for fixing the control shaft bearing cap 21. I have.
[0017]
The adjacent control shaft bearing caps 21, 21 among the plurality of control shaft bearing caps 21,..., 21 are connected by a control shaft beam 26, as shown in FIG.
[0018]
In a reciprocating internal combustion engine (an internal combustion engine not having a configuration corresponding to the control shaft 7 and the control shaft bearing cap 21 in the first embodiment described above), the crankshaft bearing cap that rotatably supports the crankshaft is used. Since only the load applied from the crankshaft was applied, if the inertia load or the combustion load of the link component was input to the crankpin, the crankshaft bearing cap would follow the deformation of the main journal of the crankshaft. The crank main journal bearing is deformed so as to fall right and left. Therefore, considering the bearing deformation state when the engine rotation speed is low, the crank main journal bearing follows the deformation of the main journal of the crankshaft, so that the contact of the main journal of the crankshaft with respect to the crank main journal bearing does not increase. .
[0019]
On the other hand, in a reciprocating variable compression ratio internal combustion engine in which a control shaft bearing cap is integrally connected to a crankshaft bearing cap as in the above-described conventional example, as shown in FIG. The deformation is caused not only by the crankshaft but also by the load from the control shaft. Here, FIG. 3 and FIG. 4 are explanatory diagrams schematically showing models focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps. 4 shows a deformation mode when both a crankshaft load and a control shaft load are applied, depending on the presence or absence of a working beam.
[0020]
Therefore, when there is no configuration corresponding to the control shaft beam 26 of the present application that connects the control shaft bearing caps to each other, the crank main journal bearing of the crankshaft bearing cap is designed to oppose the deformation of the crankshaft due to the crankpin input load. Since the portion is deformed as shown in FIG. 5 by the load of the control shaft, a partial contact occurs between the main journal of the crankshaft and the crank main journal bearing portion, and the lubrication state of the bearing portion is deteriorated. The control journal of the control cap bearing cap is deformed by the crankshaft load as shown in Fig. 6 so as to counter the control shaft deformation due to the pin journal input load of the control shaft. One-sided contact occurs between the main journal bearings, the torque required to rotate the control shaft increases, and it becomes necessary to increase the output of the actuator that rotates the control shaft.
[0021]
Thus, as in the first embodiment of the present invention described above, the rotation center P of the main journal 4a of the crankshaft 4 and the rotation center Q of the main journal 7a of the control shaft 7 are connected when viewed in the axial direction of the crankshaft 4. A control shaft beam 26 extending substantially parallel to the control shaft 7 is provided in the vicinity of the straight line L, that is, on the control shaft 7 side, and the control shaft beam 26 is attached to the control shaft bearing cap 21 to thereby control the control shaft by the control shaft load. The deformation mode of the bearing cap 21 for the crankshaft and the bearing cap 16 for the crankshaft can be changed as shown in FIG. Will follow the deformation of the crank shaft 4 by Nkupin input load, it is possible to avoid can be lubricated condition deterioration to reduce the partial contact of the crank main journal bearing 15. As a result, the friction of the crank main journal bearing 15 can be reduced.
[0022]
Further, since the deformation mode of the bearing cap 21 for the control shaft and the bearing cap 16 for the crankshaft due to the crankshaft load can be changed as shown in FIG. 8, the deformation of the bearing cap 21 for the control shaft due to the crankshaft load is reduced. 7 follows the deformation of the control shaft 7 due to the input of a load to the pin journal 9 of the control member 7, and the contact of the control main journal bearing 17 with one side can be reduced. As a result, the torque required for the rotation of the control shaft 7 is reduced, and the output of the actuator for varying the rotation position of the control shaft 7 for controlling the compression ratio can be reduced.
[0023]
FIGS. 7 and 8 are explanatory views schematically showing models focusing on a pair of adjacent crankshaft bearing caps 16 and 16 and a pair of adjacent control shaft bearing caps 21 and 21. is there.
[0024]
Also, fixing the lower side of the control shaft bearing cap 21 with the bearing beam is more distant from the main journal 4a position of the crankshaft 4 than fixing the lower side of the crankshaft bearing cap 16 with the bearing beam. Since the lower part can be fixed, by fixing the lower side of the control shaft bearing cap 21 with the control shaft beam, the moment applied to the control shaft beam 26 becomes smaller, the stress of the control shaft beam 26 is reduced, and the weight is reduced. Bearing beam shape.
[0025]
In the past, since the beam was directly connected directly below the bearing cap for the crankshaft, it was necessary to make the shape so as to avoid interference with the counterweight of the crankshaft. Alternatively, an increase in weight due to extension of the height of the crankshaft bearing cap for avoiding interference with the counterweight cannot be avoided.
[0026]
However, in the first embodiment, when the control shaft 7 is positioned diagonally below the crankshaft 4 in the crankcase, and the control shaft beam 26 is mounted below the control shaft bearing cap 21, Since interference with the counterweight 11 of the shaft 4 does not occur, the control shaft beam 26 can have a beam shape having sufficient rigidity without increasing the weight.
[0027]
Here, the difference in the surface pressure between the crank main journal bearing 15 and the control main journal bearing 17 depending on the position of the control shaft beam 26 will be described.
[0028]
FIG. 9 is an explanatory view schematically showing a model focusing on a pair of adjacent crankshaft bearing caps 16 and 16 and a pair of adjacent control shaft bearing caps 21 and 21. A and B in FIG. 9 indicate the crank main journal bearing 15, respectively, and C and D in FIG. 9 indicate the control main journal bearing 17, respectively.
[0029]
When the control shaft beam 26 is located at the position N in FIG. 9 (the control shaft beam 26 is on the control shaft 7 side), and when a load is input from both the crankshaft and the control shaft, the surface pressure at A is The surface pressure at 105 (MPa), B is 97, 9 (MPa), the surface pressure at C is 117 (MPa), and the surface pressure at D is 109 (MPa). On the other hand, the control shaft beam 26 is located at the position M in FIG. 9 (the control shaft beam 26 is on the crankshaft 4 side), and when a load is input from both the crankshaft and the control shaft, the surface at A The pressure is 115 (MPa), the surface pressure at B is 103 (MPa), the surface pressure at C is 117 (MPa), and the surface pressure at D is 111 (MPa). Incidentally, when there is no control shaft beam 26 and there is a load input from both the crankshaft and the control shaft, the surface pressure at A is 171 (MPa), the surface pressure at B is 153 (MPa), and the surface pressure at C is The pressure is 172 (MPa), and the surface pressure at D is 170 (MPa).
[0030]
This also indicates that it is desirable to provide the control shaft beam 26 on the control shaft 7 side as in the first embodiment.
[0031]
In addition, since the bearing cap 16 for the crankshaft, the bearing cap 21 for the control shaft, and the beam 26 for the control shaft are jointly fastened with the common bolt 24, the engine can be made compact, lightweight, and easy to assemble. be able to. However, a similar effect can be obtained by attaching the control shaft beam 26 even when a part of the control shaft beam 26 is connected by separate bolts.
[0032]
In order to reduce the size and weight of the engine, it is preferable that the control shaft beam cap 26 is connected to the control shaft bearing cap 21 as little as possible. In other words, in order for the effect of the control shaft beam 26 to obtain the maximum bearing friction reducing effect at the minimum coupling point, the control shaft 7 and the crankshaft 4 on which loads from both the control shaft 7 and the crankshaft 4 strongly act. It is necessary to connect the control shaft bearing cap 21 at a portion between the two.
[0033]
That is, as in the first embodiment, the control shaft beam 26 is integrally fastened to the cylinder block 10 by the bolt 24 penetrating between the control main journal bearing portion 17 and the crank main journal bearing portion 15. It is desirable to take.
[0034]
In the first embodiment, a plurality of control shaft bearing caps 16,..., 16 are connected by a single control shaft beam 26 extending along the axial direction of the control shaft 7. At least the adjacent control shaft bearing caps 21 and 21 may be connected by a plurality of control shaft beams that are substantially parallel to the shaft 7 but are discontinuous along the axial direction of the control shaft 7. Good.
[0035]
10 and 11 show a second embodiment (corresponding to claims 1 to 3). In the second embodiment, when the control shaft bearing beam 26 is viewed from the axial direction of the crankshaft 4 (FIG. 10), the rotation center P of the main journal 4a of the crankshaft 4 (the rotation center of the crankshaft) and the control shaft 7 Although provided near the straight line L connecting the rotation center (rotation center of the control shaft) Q of the main journal 7a, the control shaft beam 26 is located on the right side of the lower surface 22 of the control shaft bearing cap 21 in FIG. It is arranged.
[0036]
The control shaft beam 26 is fastened to the control shaft bearing cap 21, the crankshaft bearing cap 16 and the cylinder block 10 by bolts 25. More specifically, the control shaft beam 26 is fastened to the control shaft bearing cap 21 by the bolt 25 located on the side farther from the crankshaft 4 among the two bolts 24 and 25 fixing the control shaft bearing cap 21. ing.
[0037]
12 and 13 show a third embodiment (corresponding to claims 1 to 4). In the third embodiment, the control shaft beam 31 has substantially the same width as the lower surface 22 of the control shaft bearing cap 21. The control shaft beam 31 is fastened to the control shaft bearing cap 21 by bolts 24 and 25 for fastening the control shaft bearing cap 21 to the crankshaft bearing cap.
[0038]
14 and 15 show a fourth embodiment (corresponding to claims 1 to 4). In the fourth embodiment, the crankshaft bearing cap 40 has a substantially rectangular plate shape. The control shaft bearing cap 41 has substantially the same width as the crankshaft bearing cap 40 and is attached to the base surface of the crankshaft bearing cap 40. The control shaft beam 31 is fastened to the control shaft bearing cap 41 by bolts 23 and 24 sandwiching the crank main journal bearing 15.
[0039]
16 and 17 show a fifth embodiment (corresponding to claims 1 to 4). In the fifth embodiment, the control shaft beam 50 is fastened to the control shaft bearing cap 41 by bolts 23, 24, and 25.
[0040]
18 and 19, as in the sixth and seventh embodiments shown, the bearing cap for the control shaft and the beam for the control shaft may be integrally formed to form a ladder frame 60. Correspondence).
[0041]
In the first to seventh embodiments, the control shaft bearing caps 21 and 41 or the ladder frame 60 are fastened to the crankshaft bearing caps 16 and 40 and the cylinder block 10 by the bolt 25. As shown in FIGS. 20 to 26, the length of the bolt 25 is set short, and the bolt 25 is configured to fasten the control shaft beams 26, 31, 50 only to the control shaft bearing caps 21, 41. Is also good. In the first to seventh embodiments described above, the crankshaft bearing caps 16, 40 may be ladder frames.
[0042]
As shown in FIGS. 1, 10, 12, and 20 to 22, when there is a space below the crankshaft bearing caps 16, 40, the crankshaft bearing caps 16, 40 are provided with a space. The rigidity can be further increased by attaching the beam.
[0043]
Next, an eighth embodiment of the present invention will be described (corresponding to claim 5).
[0044]
In the eighth embodiment shown in FIGS. 27 to 30, there is a space below the bearing cap 16 for the crankshaft, and from the base surface 18 of the bearing cap 16 for the crankshaft to the lower surface 22 of the bearing cap 21 for the control shaft. , A beam member 70 are provided.
[0045]
The beam member 70 includes a crank-side beam portion 71 (crankshaft beam) attached to the base surface 18 of the crankshaft bearing cap 16 and a control-side beam portion 72 (control beam portion) attached to the lower surface of the control shaft bearing cap 21. A beam 73 for the shaft) and a rib 73 having a substantially rectangular cross section. The ribs along the side surface of the bearing cap 21 for the control shaft integrally connect the crank-side beam 71 and the control-side beam 72. I have.
[0046]
The crank side beam part 71 and the control side beam part 72 are respectively located on two planes which are parallel to each other and discontinuous to each other.
[0047]
The rib 73 is formed so that its cross-sectional shape is an elongated rectangle along the offset direction of the crank side beam part 71 and the control side beam part 72. In other words, as shown in FIG. 28, the rib 73 is formed such that the length h in the up-down direction of the crankcase is larger than the length t in the width direction of the crankcase.
[0048]
In such an eighth embodiment, a rib having a substantially rectangular cross section elongated along the offset direction of the crank side beam portion 71 and the control side beam portion 72 is provided at an intermediate position between the crank side beam portion 71 and the control side beam portion 72. 73, the rigidity of the bearing cap 16 for the crankshaft and the bearing cap 21 for the control shaft in the falling deformation direction is improved, and the thickness of the crank side beam portion 71 and the control side beam portion 72 can be reduced. 70 can be reduced in weight.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a first embodiment of the present invention.
FIG. 2 is an explanatory view showing a first embodiment of the present invention.
FIG. 3 is an explanatory view schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps.
FIG. 4 is an explanatory diagram schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps.
FIG. 5 is an explanatory view schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps, in a case where a load is applied to the control shaft. FIG.
FIG. 6 is an explanatory view schematically showing a model focusing on a pair of adjacent bearing caps for a crankshaft and a pair of adjacent bearing caps for a control shaft, when a load is applied to the crankshaft; FIG.
FIG. 7 is an explanatory view according to the present invention schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps. Explanatory drawing which shows the behavior at the time of application.
FIG. 8 is an explanatory view according to the present invention schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps. Explanatory drawing which shows the behavior at the time of application.
FIG. 9 is an explanatory view according to the present invention schematically showing a model focusing on a pair of adjacent crankshaft bearing caps and a pair of adjacent control shaft bearing caps.
FIG. 10 is an explanatory view showing a second embodiment of the present invention.
FIG. 11 is an explanatory view showing a second embodiment of the present invention.
FIG. 12 is an explanatory view showing a third embodiment of the present invention.
FIG. 13 is an explanatory view showing a third embodiment of the present invention.
FIG. 14 is an explanatory view showing a fourth embodiment of the present invention.
FIG. 15 is an explanatory view showing a fourth embodiment of the present invention.
FIG. 16 is an explanatory view showing a fifth embodiment of the present invention.
FIG. 17 is an explanatory view showing a fifth embodiment of the present invention.
FIG. 18 is an explanatory view showing a sixth embodiment of the present invention.
FIG. 19 is an explanatory view showing a seventh embodiment of the present invention.
FIG. 20 is an explanatory view showing another embodiment of the present invention.
FIG. 21 is an explanatory view showing another embodiment of the present invention.
FIG. 22 is an explanatory view showing another embodiment of the present invention.
FIG. 23 is an explanatory view showing another embodiment of the present invention.
FIG. 24 is an explanatory view showing another embodiment of the present invention.
FIG. 25 is an explanatory view showing another embodiment of the present invention.
FIG. 26 is an explanatory view showing another embodiment of the present invention.
FIG. 27 is an explanatory view showing an eighth embodiment of the present invention.
FIG. 28 is an explanatory view showing an eighth embodiment of the present invention, and is a perspective view showing a beam member.
FIG. 29 is a plan view of a beam member.
FIG. 30 is a perspective view of a beam member.
[Explanation of symbols]
4 ... Crankshaft
7 ... Control shaft
15 ... Crank main journal bearing
16 ... Bearing cap for crankshaft
17 ... Control main journal bearing
21 ... Bearing cap for control shaft
26 ... Control shaft beam

Claims (5)

An upper link connected to the piston via a piston pin; a lower link connected to the upper link and a crankpin of a crankshaft; a control shaft extending substantially parallel to the crankshaft; Having a control link movably connected and the other end connected to the lower link,
The swing center of the control link with respect to the control shaft is eccentric from the rotation center of the control shaft, and the control shaft is rotated according to engine operating conditions to adjust the distance from the crank pin to the piston pin. A reciprocating variable compression ratio internal combustion engine that variably controls an engine compression ratio,
A plurality of crankshaft bearing caps rotatably supporting the crankshaft together with a cylinder block; and a control shaft bearing cap rotatably supporting the control shaft together with the plurality of crankshaft bearing caps. Reciprocating variable compression ratio internal combustion engine provided intermittently along the axial direction of
A control shaft beam extending substantially parallel to the control shaft is provided near a straight line connecting the rotation center of the crankshaft and the rotation center of the control shaft when viewed in the axial direction of the crankshaft. Reciprocating variable compression ratio internal combustion engine. The reciprocating variable compression ratio internal combustion engine according to claim 1, wherein the plurality of control shaft bearing caps are connected by the control shaft beam. The control shaft beam is fastened to each of the control shaft bearing caps with at least one bolt, and at least one of the bolts fastens the crankshaft bearing cap and the cylinder block. The reciprocating variable compression ratio internal combustion engine according to claim 2, wherein the internal combustion engine is commonly used as a bolt. The control shaft beam is fastened to the control shaft bearing cap and the crankshaft bearing cap by a bolt penetrating between the crankshaft and the control shaft as viewed in the axial direction of the crankshaft. The reciprocating variable compression ratio internal combustion engine according to claim 2 or 3, wherein: The plurality of crankshaft bearing caps are connected by a crankshaft beam extending substantially parallel to the crankshaft, and the crankshaft beam and the control shaft beam are parallel and discontinuous to each other. And are connected via ribs along the side surfaces of the bearing cap for the control shaft along the axial direction of the control shaft.
The reciprocating device according to any one of claims 2 to 4, wherein the rib has a cross-sectional shape that is elongated in a rectangular shape along the offset direction between the crankshaft beam and the control shaft beam. -Type variable compression ratio internal combustion engine.

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