JP2010133374A - Control shaft for variable compression ratio engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control shaft for a double link type engine enabling weight reduction while maintaining shaft stiffness. <P>SOLUTION: The control shaft 20 for the variable compression ratio engine includes an upper link 13 connected to a piston 11, a lower link 14 connected to the upper link 13 and rotatably connected to a crankshaft 12, and a control link 15 connected to the lower link 14 and oscillatably connected to an eccentric part 21 of the control shaft 20. At least a shaft part 23 of the control shaft 20 between the eccentric part 21 and a journal parts 22 supported by a cylinder block includes an outer pipe 23A extending in an axial direction of the control shaft, and a reinforcement part 23B disposed in the outer pipe 23A and formed along the axial direction of the control shaft so as to keep a prescribed gap with the outer pipe 23A. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a control shaft of a variable compression ratio engine that connects a piston and a crankshaft via a plurality of links.

  Patent Document 1 discloses a multi-link engine in which a piston and a crankshaft are connected via an upper link and a lower link, and the posture of the lower link is controlled to variably control the compression ratio.

This multi-link engine has a control link with one end connected to the lower link and the other end connected to the eccentric shaft of the control shaft. By changing the rotation angle of the control shaft, the attitude of the lower link via the control link To control.
Japanese Patent Laid-Open No. 2004-92448

  However, since the multi-link engine connects the piston and the crankshaft via a plurality of links, the engine mass increases compared to a conventional engine in which the piston and the crankshaft are connected by a single connecting rod. When the engine mass increases in this way, even if the compression ratio is variably controlled according to the engine operating state, the effect of improving the fuel efficiency in the multi-link engine is reduced.

  In order to suppress the decrease in the improvement effect of the fuel efficiency, it is necessary to suppress the increase in the engine mass of the multi-link engine as much as possible.

  Accordingly, the present invention has been made paying attention to such problems, and an object thereof is to provide a control shaft of a multi-link engine that can be reduced in weight while maintaining the shaft rigidity.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an upper link (13) connected to the piston (11), a lower link (14) connected to the upper link (13) and rotatably connected to the crankshaft (12), and a lower link. A control shaft (20) of a variable compression ratio engine comprising: a control link (15) coupled to (14) and swingably coupled to an eccentric portion (21) of the control shaft (20); A shaft portion (23) between at least the eccentric portion (21) of the control shaft (20) and the journal portion (22) supported by the cylinder block has an outer tube (23A) extending in the control shaft axial direction and an outer portion. It is arranged in the pipe (23A) and is formed along the control shaft axial direction so as to have a predetermined gap with the outer pipe (23A). And a reinforcement portion (23B), characterized in that.

  According to the present invention, the shaft portion of the control shaft is formed along the control shaft axial direction so as to have a predetermined gap between the outer pipe extending in the control shaft axial direction and the outer pipe. Therefore, the weight of the control shaft can be reduced while ensuring the rigidity of the control shaft. As a result, an increase in engine mass can be suppressed, and a reduction in fuel efficiency improvement effect in a multi-link variable compression ratio engine can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a multi-link engine according to the first embodiment.

  Referring to FIG. 1, a multi-link engine 100 is an in-line four-cylinder engine for a vehicle, and includes a compression ratio variable mechanism 10 that changes a compression ratio by changing a piston top dead center position. The variable compression ratio mechanism 10 connects the piston 11 and the crankshaft 12 by an upper link 13 and a lower link 14 and changes the compression ratio by controlling the posture of the lower link 14 by a control link 15.

  The upper end of the upper link 13 is connected to the piston 11 via a piston pin 16. The lower end of the upper link 13 is connected to the lower link 14 via the upper pin 17.

  The lower link 14 is connected to the upper link 13 at one end and is connected to the control link 15 via the control pin 18 at the other end. The lower link 14 can be divided from two members on the left and right in the figure, and has a connecting hole 14A in the approximate center. The lower link 14 inserts the crank pin 12A of the crank shaft 12 into the connecting hole 14A and swings about the crank pin 12A.

  The crankshaft 12 includes a crankpin 12A, a journal 12B, and a counterweight 12C. The center of the crankpin 12A is eccentric by a predetermined amount from the center of the journal 12B. The counterweight 12C is integrally formed with the crank arm and reduces the primary vibration component of the piston motion.

  The upper end of the control link 15 is rotatably connected to the lower link 14 via a control pin 18. The lower end of the control link 15 is connected to the eccentric portion 21 of the control shaft 20. The control link 15 swings around the eccentric portion 21.

  The control shaft 20 is disposed in parallel with the crankshaft 12 and is rotatably supported by the cylinder block. The eccentric portion 21 of the control shaft 20 is formed at a position eccentric by a predetermined amount from the control shaft axis. The control shaft 20 is rotationally controlled by an actuator (not shown) and moves the eccentric portion 21.

  When the control shaft 20 is rotated by the actuator and the eccentric portion 21 moves in a direction relatively lower than the central axis of the control shaft 20, the position of the upper pin 17 relative to the lower link 14 is relatively centered on the crank pin 12A. Tilt to ascend. Thereby, piston 11 raises and the compression ratio of multi-link type engine 100 becomes high. On the other hand, when the eccentric portion 21 moves in a direction that is relatively high with respect to the central axis of the control shaft 20, the lower link 14 is in a direction in which the position of the upper pin 17 is relatively low about the crank pin 12A. Tilt. As a result, the piston 11 is lowered, and the compression ratio of the multi-link engine 100 is lowered.

  In the multi-link engine 100, for example, in order to improve the output in the low and medium load operation region where the low compression ratio is set to prevent knocking in the high load operation region regardless of the engine rotation speed and the possibility of knocking is low. High compression ratio is set.

  By the way, in the multi-link engine in which the piston and the crankshaft are connected via a plurality of links, the engine mass is increased as compared with a conventional engine in which the piston and the crankshaft are connected by a single connecting rod. When the engine mass increases, even if the compression ratio is variably controlled according to the engine operating state, the effect of improving the fuel efficiency in the multi-link engine is reduced. In a multi-link engine, a load caused by combustion pressure, inertial force of each link, etc. acts on the eccentric part of the control shaft, so it is important to secure the shaft rigidity of the control shaft.

  Therefore, in the multi-link engine 100, the weight of the control shaft is reduced while securing the shaft rigidity of the control shaft 20.

  FIG. 2 is a schematic configuration diagram of the control shaft 20 in the multi-link engine 100. FIG. 2A shows a cross section of the control shaft 20 in the axial direction of the control shaft. 2 (B) to 2 (D) show cross sections of the journal portion 22, the eccentric portion 21, and the shaft portion 23 in a direction orthogonal to the control shaft axial direction.

  Referring to FIG. 2A, in the control shaft 20, the eccentric portions 21 and the journal portions 22 are alternately arranged along the control shaft axial direction, and the eccentric portions 21 and the journal portions 22 are connected by the shaft portion 23. This is a bar-shaped member configured as described above. The control shaft 20 has the same number of eccentric portions 21 as the number of cylinders, has five journal portions 22 so that both ends of the control shaft become journal portions 22, and connects the eccentric portions 21 and the journal portions 22. 8 shaft portions 23 are provided.

  2A and 2B, the journal portion 22 is formed in a cylindrical shape. The journal portion 22 is rotatably supported by the cylinder block of the multi-link engine 100. The journal portion 22 is formed with an oil passage 22A for flowing the supplied lubricating oil in the axial direction of the control shaft and a branch passage 22B for branching from the oil passage 22A and for flowing the lubricating oil to the outer peripheral surface of the journal. The axis of the journal portion 22 coincides with the rotation center of the control shaft 20.

  Referring to FIGS. 2A and 2C, the eccentric portion 21 has a cylindrical shape and is arranged to be eccentric from the rotation center of the control shaft 20. A control link 15 of the multi-link engine 100 is swingably provided on the outer periphery of the eccentric portion 21. The eccentric portion 21 is formed with an oil passage 21A for flowing the lubricating oil in the axial direction of the control shaft and a branch passage 21B branching from the oil passage 21A and flowing the lubricating oil to the outer peripheral surface of the eccentric portion.

  Referring to FIGS. 2 (A) and 2 (D), the shaft portion 23 has a double tube structure, and an outer tube 23A and an inner tube 23B having a smaller diameter than the outer tube 23A and disposed in the outer tube 23A. With. Both the outer tube 23 </ b> A and the inner tube 23 </ b> B connect the eccentric portion 21 and the journal portion 22. The axial centers of the outer tube 23A and the inner tube 23B coincide with the rotation center of the control shaft 20, respectively. In the shaft portion 23, a gap between the outer tube 23A and the inner tube 23B serves as an oil passage 23C for flowing lubricating oil in the control shaft axial direction.

  In the control shaft 20, the oil passage 21A of the eccentric portion 21, the oil passage 22A of the journal portion 22, and the oil passage 23C of the shaft portion 23 are configured to communicate with each other.

  FIG. 3 is a diagram showing the relationship between the control shaft mass and the sectional second moment of the shaft portion of the control shaft. The cross-sectional second moment in the shaft portion represents the shaft rigidity of the control shaft.

  A circle in FIG. 3A shows a control shaft 120 of a conventional multi-link engine, and the shaft portion 123 has a circular cross section as shown in FIG. 3B. In the conventional control shaft 120, when the passage diameter of the oil passage 123C is increased, the mass of the control shaft becomes lighter as shown by a circle in FIG.

  3A is a control shaft 220 in which the outer diameter of the shaft portion 223 is the same as that of the conventional control shaft 120 and the passage diameter of the oil passage 223C is formed larger than that of the conventional control shaft 120. A case where the cross section of the shaft portion 223 is annular as shown in FIG. In the control shaft 220 as a comparative example, as the passage diameter of the oil passage 223C increases, the mass of the control shaft becomes lighter than that of the conventional control shaft 120 as shown by the triangular mark in FIG. It will decline.

  A square mark in FIG. 3 (A) shows the control shaft 20 of the multi-link engine 100, and the shaft portion 23 has a double tube shape as shown in FIG. 3 (D). In the control shaft 20, the outer diameter of the outer tube 23 </ b> A of the shaft portion 23 is slightly larger than that of the shaft portion 124 of the conventional control shaft 120, but as compared with the conventional control shaft 120 as indicated by the square marks in FIG. Thus, it is possible to reduce the weight of the control shaft while ensuring the sectional moment of inertia of the shaft portion 23 to be equal to or higher than that.

  Note that when the shape of the inner tube 23B is reduced in the control shaft 20, the mass of the control shaft is reduced and the cross-sectional secondary moment of the shaft portion 23 is also reduced, as indicated by the square marks in FIG.

  As described above, in the control shaft 20 of the multi-link engine 100 of the first embodiment, the following effects can be obtained.

  Since the shaft portion 23 of the control shaft 20 has a double-pipe structure and the inner tube 23B as a reinforcing member is disposed inside the outer tube 23A, the weight of the control shaft can be reduced while ensuring the rigidity of the control shaft. it can. Thereby, an increase in engine mass can be suppressed, and a decrease in the improvement effect of fuel efficiency in the multi-link engine 100 can be suppressed.

  Further, in the control shaft 20, since the oil passage 21A of the eccentric portion 21 and the oil passage 22A of the journal portion 22 are communicated with the gap between the outer tube 23A and the inner tube 23B of the shaft portion 23, a passage through which lubricating oil flows. Can have a relatively simple configuration.

(Second Embodiment)
The basic configuration of the multi-link engine 100 of the second embodiment is substantially the same as that of the first embodiment, but differs in the configuration of the control shaft 20. That is, the shaft portion 23 of the control shaft 20 is a single rod-like member extending in the control shaft axial direction, and the difference will be mainly described below.

  FIG. 4A is a schematic configuration diagram of the control shaft 20 of the multi-link engine 100 of the second embodiment. FIG. 4B is a cross section of the shaft portion 23 of the control shaft 20 in a direction orthogonal to the control shaft axial direction, and is a cross section taken along the line B-B of FIG.

  Referring to FIG. 4A, the control shaft 20 includes a single shaft portion 23 extending in the control shaft axial direction. The shaft portion 23 includes an outer tube 23A whose both ends are closed, and an inner tube 23B disposed concentrically inside the outer tube 23A.

  The eccentric portions 21 and the journal portions 22 that are alternately arranged along the control shaft axial direction are fitted to the outer periphery of the outer tube 23 </ b> A of the shaft portion 23. The eccentric part 21 and the journal part 22 are arranged in the same manner as in the first embodiment.

  The inner tube 23B of the shaft portion 23 is fixed so as to connect both ends of the outer tube in the outer tube 23A. As shown in FIG. 4B, a pair of contact portions 23D that contact a part of the inner peripheral surface of the outer tube 23A is formed on the outer periphery of the inner tube 23B. The pair of abutting portions 23D are disposed 180 degrees apart from the center of the inner tube, and are formed along the control shaft axial direction.

  An introduction hole 23E for introducing the lubricating oil into the oil passage 23C between the outer tube 23A and the inner tube 23B is formed on one closed end face of the outer tube 23A. The lubricating oil introduced into the oil passage 23C flows into the branch passage 21B of the eccentric portion 21 and the branch passage 22B of the journal portion 22 through a plurality of branch passages 23F provided in the radial direction of the outer tube 23A.

  In the control shaft 20 described above, the contact portion 23D is formed on the inner tube 23B of the shaft portion 23. Therefore, the cross-sectional secondary moment of the shaft portion 23 is a line passing through the center of the inner tube 23B and the center of the contact portion 23D. The cross-sectional secondary moment in the x direction is larger than the cross-sectional secondary moment in the line y direction perpendicular to the line x.

  FIG. 5 is a diagram illustrating the relationship between the control shaft mass and the sectional second moment of the shaft portion 23 of the control shaft 20 in the direction of the line x.

  5 represents the conventional control shaft 120 in FIG. 3A, and the square in FIG. 5 represents the control shaft 20 of the multi-link engine 100. In the control shaft 20 according to the second embodiment, the outer diameter of the outer tube 23A of the shaft portion 23 is slightly larger than that of the conventional control shaft 120, but as shown in FIG. The weight of the control shaft can be reduced while ensuring the same or better.

  Note that when the shape of the inner tube 23B is reduced in the control shaft 20, the mass of the control shaft is reduced and the secondary moment of the section of the shaft portion 23 is also reduced, as shown by the square marks in FIG.

  By the way, the load caused by the combustion pressure, the inertial force of each link, etc. is applied to the eccentric portion 21 of the control shaft 20 of the multi-link engine 100 as shown by the arrow in FIG. ). The load acting on the eccentric portion 21 of the control shaft 20 is larger at the time of high engine load at which the compression ratio is low than at the time of engine low load at which the compression ratio is high.

  FIG. 6B is a diagram showing the load acting on the eccentric portion 21 of the control shaft 20 as a load vector when the compression ratio is low. The X axis is a direction orthogonal to the piston moving direction, and the Y axis is the piston moving direction. The center of the eccentric portion 21 of the control shaft 20 is the coordinate center.

Referring to FIG. 6B, the load acting on the eccentric portion 21 of the control shaft 20 changes according to the swing region R ₁ of the control link 15, and the piston in which the air-fuel mixture burns as indicated by the load vector A is shown. Maximum near top dead center.

  Therefore, in the second embodiment, the control shaft 20 is installed in the multi-link engine 100 so that the line x passing through the center of the inner tube 23B of the shaft portion 23 and the center of the contact portion 23D is parallel to the load vector A. To do. Since the shaft rigidity in the direction of the line x is increased in the control shaft 20, the deflection of the control shaft 20 can be suppressed even if the maximum load acts on the eccentric portion 21.

  As described above, the control shaft 20 of the multi-link engine 100 of the second embodiment can obtain the following effects.

  Since the shaft portion 23 of the control shaft 20 has a double tube structure and the inner tube 23B as a reinforcing member is arranged inside the outer tube 23A, the same effect as in the first embodiment can be obtained.

  Further, since the control shaft 20 forms a contact portion 23D that contacts the inner peripheral surface of the outer tube 23A on the inner tube 23B of the shaft portion 23, a line passing through the center of the inner tube 23B and the center of the contact portion 23D. The shaft rigidity in the x direction can be increased. Therefore, the control shaft 20 is a multi-link type so that the line x passing through the center of the inner tube 23B and the center of the contact portion 23D is parallel to the maximum load vector of the load acting on the eccentric portion 21 at the time of the low compression ratio. By installing the engine 100, even if the maximum load acts on the eccentric portion 21, the deflection of the control shaft 20 can be suppressed.

  Further, the shaft portion 23 of the control shaft 20 is composed of one outer tube 23A extending in the control shaft axial direction and an inner tube 23B disposed inside the outer tube 23A. As a result, the oil passage 23C between the outer pipe 23A and the inner pipe 23B can have a uniform cross section along the axial direction of the control shaft, and the hydraulic loss of the lubricating oil can be reduced as compared with the first embodiment. It becomes possible.

(Third embodiment)
The basic configuration of the multi-link engine 100 of the third embodiment is substantially the same as that of the second embodiment, but differs in the configuration of the control shaft 20. That is, the configuration of the outer tube 23A of the shaft portion 23 is simplified, and the difference will be mainly described below.

  FIG. 7A is a schematic configuration diagram of the control shaft 20 of the multi-link engine 100 of the third embodiment. FIG. 7B is a cross section of the shaft portion 23 of the control shaft 20 in a direction orthogonal to the control shaft axial direction, and is a cross section taken along the line B-B of FIG.

  As shown in FIGS. 7A and 7B, the control shaft 20 in the third embodiment is different from the second embodiment only in the configuration of the outer tube 23A of the shaft portion 23, and the others are in the second embodiment. Is the same.

  The outer tube 23A of the shaft portion 23 of the control shaft 20 is formed as one circular tube extending along the control shaft axial direction. An eccentric portion 21 and a journal portion 22 are integrally formed on the outer tube 23A. The outer tube 23A can be manufactured by press-molding a circular tube. Note that the outer tube 23A can be manufactured not by press molding but also by sintering molding in which metal powder is sintered.

  As described above, the control shaft 20 of the multi-link engine 100 of the third embodiment can obtain the following effects.

  In the control shaft 20, since the eccentric portion 21 and the journal portion 22 are integrally formed on the outer tube 23A of the shaft portion 23, not only the same effect as in the second embodiment can be obtained, but also the number of parts of the shaft portion 23 can be reduced. It is possible to reduce the man-hours for manufacturing the control shaft.

(Fourth embodiment)
The basic configuration of the multi-link engine 100 of the fourth embodiment is substantially the same as that of the second embodiment, but is different in the configuration of the control shaft 20. That is, the plate-like member 23G is provided in the outer tube 23A of the shaft portion 23, and the difference will be mainly described below.

  FIG. 8A shows a cross section of the shaft portion 23 of the control shaft 20 in a direction orthogonal to the control shaft axial direction in the multi-link engine 100 of the fourth embodiment, which replaces FIG. 4B. .

  In the second embodiment, the shaft portion has a double tube structure, but in the control shaft 20 in the fourth embodiment, a plate-like member 23G is disposed in the outer tube 23A of the shaft portion 23 as shown in FIG. To do.

  The plate-like member 23G has a two-sided width 23H composed of two surfaces parallel to each other across the center of the member, and a contact portion 23D that faces the center of the member and a part of the inner peripheral surface of the outer tube 23A. With. The plate-like member 23G is formed along the control shaft axial direction. A gap between the two-surface width 23H of the plate-like member 23G and the outer tube 23A becomes an oil passage 23C.

  The plate-like member 23G is formed of a metal member having a higher coefficient of thermal expansion than the outer tube 23A. By utilizing this thermal expansion difference, the plate-like member 23G is inserted into the outer tube 23A and fixed without being welded or the like.

  In the control shaft 20, since the plate-like member 23G is disposed in the outer tube 23A of the shaft portion 23, the second-order moment of the cross-section of the shaft portion 23 is parallel to the two-plane width 23H at the member center of the plate-like member 23G. The cross-sectional secondary moment in the direction of the line x passing therethrough is larger than the cross-sectional secondary moment in the direction of the line y perpendicular to the line x.

  FIG. 8B is a diagram illustrating the relationship between the control shaft mass and the cross-sectional secondary moment of the shaft portion 23 of the control shaft 20 in the direction of the line x.

  In FIG. 8B, a circle indicates the conventional control shaft 120, and a square indicates the control shaft 20 of the multi-link engine 100. In the control shaft 20, the outer diameter of the outer tube 23A of the shaft portion 23 is slightly larger than that of the conventional control shaft 120, but the sectional moment of inertia of the shaft portion 23 is the same as shown in FIG. The control shaft mass can be reduced while ensuring the above.

  Note that when the width of the two-surface width 23H of the plate-like member 23G is reduced in the control shaft 20, the control shaft mass is reduced and the cross-sectional secondary moment of the shaft portion 23 is also reduced as shown by the square marks in FIG. descend.

  As described above, the following effects can be obtained in the control shaft 20 of the multi-link engine 100 of the fourth embodiment.

  In the control shaft 20, since the plate-like member 23G having the two-surface width 23H is arranged in the outer tube 23A of the shaft portion 23, the weight of the control shaft can be reduced while ensuring the rigidity of the control shaft.

  Further, in the control shaft 20, since the abutting portion 23D is formed on the plate-like member 23G, the sectional secondary moment on the abutting portion side of the shaft portion 23 can be made larger than the sectional secondary moment on the two-plane width side. it can. Therefore, by installing the control shaft 20 in the multi-link engine 100 so that the line x in the shaft portion 23 is parallel to the maximum load vector of the load acting on the eccentric portion 21 at the time of the low compression ratio, the maximum load is increased. Even if it acts on the eccentric portion 21, it is possible to suppress the deflection of the control shaft 20.

(Fifth embodiment)
The basic configuration of the multi-link engine 100 of the fifth embodiment is substantially the same as that of the second embodiment, but is different in the configuration of the control shaft 20. That is, the cross section of the shaft portion 23 of the control shaft 20 is elliptical, and the difference will be mainly described below.

  FIG. 9A shows a cross section of the shaft portion 23 of the control shaft 20 in the direction orthogonal to the control shaft axial direction in the multi-link engine 100 of the fifth embodiment, which replaces FIG. 4B. .

  As shown in FIG. 9A, the shaft portion 23 of the control shaft 20 has a double tube structure, and the outer tube 23A and the inner tube 23B have an elliptical cross section. The inner tube 23B is arranged in the outer tube 23A so that the major axis of the inner tube 23B is located on the major axis of the outer tube 23A and the minor axis of the inner tube 23B is located on the minor axis of the outer tube 23A. . A pair of abutting portions 23D that abuts a part of the inner circumferential surface of the outer tube 23A is formed on the outer circumference of the inner tube 23B on the long axis side. The abutting portion 23D is formed on a line x including the long axis of the inner tube 23B, and is disposed 180 ° apart from the center of the inner tube.

  As described above, the control shaft 20 of the multi-link engine 100 of the fifth embodiment can obtain the following effects.

  Since the shaft portion 23 of the control shaft 20 has a double tube structure and the inner tube 23B as a reinforcing member is arranged inside the outer tube 23A, the weight of the control shaft is reduced while ensuring the rigidity of the control shaft. Can be achieved.

  Further, the control shaft 20 forms an abutting portion 23D on the long axis side of the inner tube 23B of the shaft portion 23, and the cross sections of the outer tube 23A and the inner tube 23B are each elliptical. The cross-sectional secondary moment on the shaft side can be made larger than the cross-sectional secondary moment on the short shaft side. Therefore, by installing the control shaft 20 in the multi-link engine 100 so that the line x in the shaft portion 23 is parallel to the maximum load vector of the load acting on the eccentric portion 21 at the time of the low compression ratio, the maximum load is increased. Even if it acts on the eccentric portion 21, it is possible to suppress the deflection of the control shaft 20.

  In the control shaft 20 in the fifth embodiment, the outer tube 23A and the inner tube 23B are both elliptical. However, as shown in FIG. 9B, the outer tube 23A has a circular cross section, and the inner tube 23B has a cross section. May be elliptical. The control shaft 20 shown in FIG. 9B is configured such that the outer peripheral surface on the long axis side of the inner tube 23B is in contact with a part of the inner peripheral surface of the outer tube 23A. Also in the control shaft 20 configured in this way, the same effect as in the fifth embodiment can be obtained.

  Further, in the control shaft 20 in FIG. 9B, the lubricating oil is allowed to flow through the oil passage 23C in the gap between the outer tube 23A and the inner tube 23B. However, as shown in FIG. You may make it provide the oil supply pipe 30 which flows lubricating oil along a control shaft axial direction inside. When the clearance area between the outer pipe 23A and the inner pipe 23B is large, there is a problem that the amount of lubricating oil increases too much. However, as shown in FIG. 9C, an oil supply pipe 30 is separately provided in the inner pipe 23B. The above problem can be solved. Such an oil supply pipe 30 may be provided in the inner tube of the control shaft of the second and third embodiments.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, the idea of the invention described in the fourth and fifth embodiments can be applied to the control shaft of the third embodiment.

1 is a schematic configuration diagram of a multi-link engine of a first embodiment. It is a schematic block diagram of the control shaft of a multi-link type engine. It is a figure which shows the relationship between a control shaft mass and the cross-sectional secondary moment of the axial part of a control shaft. It is a schematic block diagram of the control shaft of the multiple link type engine of 2nd Embodiment. 4 is a diagram illustrating a relationship between a control shaft mass and a cross-sectional secondary moment of a shaft portion 23 of the control shaft 20. FIG. It is a figure explaining the load which acts on the eccentric part of a control shaft. It is a schematic block diagram of the control shaft of the multilink type engine of 3rd Embodiment. It is a schematic block diagram of the control shaft of the multilink type engine of 4th Embodiment. It is a schematic block diagram of the control shaft of the multilink type engine of 5th Embodiment.

Explanation of symbols

100 Multi-link engine 11 Piston 12 Crankshaft 13 Upper link 14 Lower link 15 Control link 20 Control shaft 21 Eccentric part 23 Shaft part 23A Outer pipe 23B Inner pipe 23C Oil passage 23D Abutting part 23G Plate-like member 23H Oil supply pipe

Claims (11)

An upper link connected to the piston, a lower link connected to the upper link and rotatably connected to the crankshaft, and connected to the lower link and swingably connected to an eccentric portion of the control shaft. A control shaft of a variable compression ratio engine comprising:
A shaft portion between at least the eccentric portion and the journal portion supported by the cylinder block of the control shaft is
An outer tube extending in the axial direction of the control shaft;
A reinforcing portion disposed in the outer tube and formed along the control shaft axial direction so as to have a predetermined gap with the outer tube;
A control shaft of a variable compression ratio engine characterized by comprising: The outer tube is formed as a circular tube,
The reinforcing part is formed as a circular pipe having a smaller diameter than the outer pipe,
The journal portion and the eccentric portion are connected in the control shaft axial direction by the outer tube and the inner tube.
The control shaft of the variable compression ratio engine according to claim 1. The outer tube is formed as a circular tube,
The reinforcing portion is a circular tube having a smaller diameter than the outer tube, and is formed so as to have an abutting portion that abuts on the inner peripheral surface of the outer tube on the outer peripheral surface,
The journal part and the eccentric part are arranged so as to be fitted to the outer periphery of the outer pipe,
The control shaft of the variable compression ratio engine according to claim 1. The outer tube is formed as a tube having an elliptical cross section in a direction perpendicular to the control shaft axial direction,
The reinforcing portion is a tube having an elliptical cross section in a direction perpendicular to the control shaft axial direction, and has a contact portion that contacts the long-axis-side inner peripheral surface of the outer tube on the long-axis-side outer peripheral surface. Formed,
The journal part and the eccentric part are arranged so as to be fitted to the outer periphery of the outer pipe,
The control shaft of the variable compression ratio engine according to claim 1. The outer tube is formed as a circular tube,
The reinforcing portion is a tube having an elliptical cross section in a direction orthogonal to the control shaft axial direction, and the long-axis-side outer peripheral surface is formed as a contact portion that contacts the inner peripheral surface of the outer tube,
The journal part and the eccentric part are arranged so as to be fitted to the outer periphery of the outer pipe,
The control shaft of the variable compression ratio engine according to claim 1. The outer tube is formed as a circular tube,
The reinforcing portion is a plate-like member that is formed in the axial direction of the control shaft and has a two-sided width composed of two surfaces facing each other across the center of the member, and a contact portion that contacts the inner peripheral surface of the outer tube. And
The journal portion and the eccentric portion are configured to be fitted to the outer periphery of the outer tube.
The control shaft of the variable compression ratio engine according to claim 1. The journal portion and the eccentric portion are integrally formed with the outer tube.
The control shaft of the variable compression ratio engine according to any one of claims 3 to 6, wherein the control shaft is a variable compression ratio engine. The contact portions are formed as a pair and are spaced apart from the center of the reinforcing portion by 180 °.
The control shaft of the variable compression ratio engine according to any one of claims 3 to 6, wherein the control shaft is a variable compression ratio engine. The control shaft includes a direction of a load acting on an eccentric portion of the control shaft when the piston is in a predetermined position near top dead center at the time of air-fuel mixture combustion at a low compression ratio, the center of the contact portion, and the It is arranged so that the direction of the line connecting the reinforcement part center is parallel,
The control shaft of the variable compression ratio engine according to claim 8. The predetermined gap is an oil passage through which lubricating oil flows.
The control shaft of the variable compression ratio engine according to any one of claims 1 to 9, wherein the control shaft is a variable compression ratio engine. An oil passage for flowing lubricating oil is formed inside the reinforcing portion.
The control shaft of the variable compression ratio engine according to any one of claims 3 to 5, wherein the control shaft is a variable compression ratio engine.

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