JP2009293475A - Bearing structure of multilink engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the fastening force of a bearing cap to a cylinder head. <P>SOLUTION: The bearing structure for a multilink engine includes a crankshaft main bearing-cap 20 which supports the main shaft-part 2a of the crankshaft 2 with respect to a cylinder block 10, and a fastening bolt 41 which is provided on the opposite side to a control shaft 3 with respect to the center of the crankshaft 2, and whose tip end is screwed down in the cylinder block 10 to reach a height nearly the same as the lower end of the cylinder, and fastens the crankshaft main bearing-cap 20 to the cylinder block 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing structure for a multi-link engine.

As a conventional multi-link engine bearing structure, there is one in which a bearing cap that supports a crankshaft and a control shaft is fastened to a cylinder block with three cap bolts (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2004-92448

  In the multi-link type engine, the reciprocating inertia force of the piston acting on the crankshaft bearing portion is increased as compared with the single-link type engine. For this reason, the bearing structure of the multi-link type engine described above has a problem that the margin of the fastening force of the bearing cap to the cylinder head by the cap bolt is not sufficient for the downward load acting on the crankshaft bearing portion. It was.

  The present invention has been made paying attention to such a conventional problem, and an object thereof is to increase the fastening force of the bearing cap to the cylinder head by the cap bolt.

  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 (11) having one end connected to a piston (14) via a piston pin (15), the other end of the upper link (11), and a crank pin (2b) of a crankshaft (2). A lower link (12) coupled to the crankshaft (2), a control shaft (3) disposed substantially parallel to the crankshaft (2), and one end pivotably coupled to the control shaft (3) and the other end And a control link (13) connected to the lower link (12), and a bearing structure of a multi-link engine (1), wherein the crankshaft (2) is connected to a cylinder block (10). A crankshaft main bearing cap (20) for supporting the main shaft portion (2a), and the control shaft (with respect to the center of the crankshaft (2)) ) And is screwed into the cylinder block (10) until the tip is substantially the same height as the cylinder lower end, and the crankshaft main bearing cap (20) is attached to the cylinder block (10). ) And a fastening bolt (41) to be fastened.

  Since the tip end of the member fastening bolt is extended to the cylinder lower end, the fastening force of the bearing fastening bolt to the cylinder head by the member fastening bolt increases.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, a schematic configuration of the multi-link engine 1 and a support structure for the crankshaft 2 and the control shaft 3 will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic configuration diagram of a multi-link engine 1 in which the compression ratio can be changed. FIG. 2 is a schematic view of a support structure for the crankshaft 2 and the control shaft 3.

  As shown in FIG. 1, the multi-link engine 1 connects the piston 14 and the crankshaft 2 with two links (upper link 11 and lower link 12), and controls the lower link 12 with a control link 13. Change the compression ratio.

  The upper link 11 has an upper end connected to the piston 14 via a piston pin 15 and a lower end connected to one end of the lower link 12 via a connection pin. The piston 14 receives the combustion pressure and reciprocates the cylinder 10 a of the cylinder block 10.

  One end of the lower link 12 is connected to the upper link 11 via the first connecting pin 16, and the other end is connected to the control link 13 via the second connecting pin 17. The lower link 12 has a crank pin 2b of the crankshaft 2 inserted into a substantially central connecting hole 12a, and swings about the crank pin 2b as a central axis.

  The crankshaft 2 includes a plurality of crank journals 2a, crank pins 2b, and counterweights 2c.

  As shown in FIG. 2, the crank journal 2 a is rotatably supported by a crankshaft bearing portion 21 formed on the lower surface of the cylinder block 10 on the upper half and on the upper surface of the crankshaft cap 20. The crankshaft cap 20 is fastened to the cylinder block 10 from below by a first cap bolt 41. This 1st cap volt | bolt 41 is a volt | bolt arrange | positioned with respect to the centerline A of the crank journal 2a on the opposite side to the side by which the control shaft 3 is arrange | positioned.

  A description will be given with reference to FIG. 1 again. The crank pin 2b is eccentric from the crank journal 2a by a predetermined amount, and the lower link 12 is pivotably connected thereto.

  The counterweight 2c is provided on the arm portion that connects the crank journal 2a and the crankpin 2b, and removes the weight imbalance of the rotating portion.

  One end of the control link 13 is connected to the lower link 12 via the second connection pin 17, and the other end is connected to the control pin 3 b of the control shaft 3. The control pin 3b of the control shaft 3 has an axial center at a position eccentric from the control journal 3a by a predetermined amount. Therefore, when the control shaft 3 is rotated by the actuator 32, the position of the control pin 3b moves.

  As shown in FIG. 2, the control journal 3 a is rotatably supported by a control shaft bearing 31 formed on the lower surface of the crankshaft cap 20 on the upper half and on the upper surface of the control shaft cap 30 on the lower half. . The control shaft cap 30 and the crankshaft cap 20 described above are fastened to the cylinder block 10 from the lower side by the second cap bolt 42 and the third cap bolt 43.

  FIG. 3 is a diagram for explaining a compression ratio changing method of the multi-link engine 1.

  The multi-link engine 1 changes the compression ratio by rotating the control shaft 3 and changing the position of the control pin 3b.

  For example, as shown in FIGS. 3 (A) and 3 (C), when the control pin 3b is set to the position P, the top dead center position (TDC) is increased and a high compression ratio is obtained.

  On the other hand, if the control pin 3b is moved to the position Q as shown in FIGS. 3B and 3C, the control link 13 is pushed upward, and the position of the second connecting pin 17 is raised. As a result, the lower link 12 rotates counterclockwise about the crank pin 2b, the first connecting pin 16 is lowered, and the position of the piston pin 15 at the piston top dead center (TDC) is lowered. Therefore, the compression ratio becomes a low compression ratio.

  Further, the multi-link engine 1 can obtain a piston stroke characteristic close to a single vibration as compared with a conventional single link engine in which a piston and a crankshaft are connected by a single link (connecting rod). This will be described below with reference to FIG.

  FIG. 4 is a diagram showing the piston stroke characteristics (solid line) of the multi-link engine 1 and the piston stroke characteristics (broken line) of the single link engine.

  As shown by a broken line in FIG. 4, in the conventional single link type engine, the piston has a fast movement (high acceleration) near the top dead center and a slow movement (low acceleration) near the bottom dead center.

  On the other hand, as shown by a solid line in FIG. 4, the multi-link engine 1 can obtain a piston stroke characteristic close to simple vibration by appropriately setting the link configuration. Therefore, the piston acceleration is leveled, and the piston speed near the bottom dead center becomes faster than the conventional one.

  Here, with reference to FIG. 5, a problem newly generated due to the leveling of the piston acceleration will be described.

  FIG. 5A is a diagram schematically showing a downward load acting on the crankshaft bearing portion 21 of the single link type engine. FIG. 5 (B) is a diagram schematically showing a downward load acting on the crankshaft bearing portion 21 of the multi-link engine.

  As shown in FIGS. 5A and 5B, the crankshaft bearing 21 is subjected to a reciprocating inertia force generated by the reciprocating motion of the piston in addition to the combustion load. At this time, as shown in FIG. 5B, in the case of a multi-link engine having a fast piston speed near bottom dead center, the reciprocation acting on the crankshaft bearing portion 21 when the piston reaches bottom dead center. Inertia increases.

  When the reciprocating inertia force increases, when a downward load is applied to the crankshaft bearing portion 21, the crankshaft cap 20 may be deformed, and a so-called opening may occur in which a gap is formed between the cylinder block 10 and the crankshaft cap 20. There is.

  Therefore, in this embodiment, in order to prevent this opening, the length of the first cap bolt 41 is extended to the lower end position of the cylinder 10a.

  FIG. 6 is a schematic view showing the first cap bolt 41, the second cap bolt 42, and the third cap bolt 43 that are screwed into the cylinder block 10.

  As shown in FIG. 6, in the present embodiment, the length of the first cap bolt 41 is extended to the lower end position of the cylinder 10a. Thereby, since the fastening force of the cylinder block 10 and the crankshaft cap increases, it is possible to prevent the opening of the mouth.

  The cylinder block 10 at the lower end of the cylinder 10 a is formed with a notch 10 b that has a deeper bottom than the tip of the first cap bolt 41. The notch 10b will be described with reference to FIG.

  FIG. 7A is a bottom view of the cylinder block 10, and FIG. 7B is an enlarged view of a dotted line part of FIG. 7A.

  As shown in FIG. 7A, the cylinder block 10 is formed with four cylinders 10a, and bolt holes 41a into which the first cap bolt 41, the second cap bolt 42, and the third cap bolt 43 are screwed. , 42a, 43a are formed on both sides of each cylinder 10a.

  As shown in FIG. 7B, in this embodiment, four notches 10b are formed in the cylinder block 10 at the lower end of the cylinder 10a. The notches 10b are provided so as to be vertically symmetrical with respect to each cylinder 10a at two locations in the upper half and the lower half in the cylinder row direction. In FIG. 7, two notches 10b provided in the lower half of the cylinder row direction are provided in the vicinity of the bolt holes 41a.

  By this notch, the tensile load of the first cap bolt 41 acting in the direction indicated by the arrow in FIG. 7B can be reduced. Therefore, the deformation amount of the cylinder 10a due to the tensile load of the first cap bolt 41 can be reduced. As a result, the surface pressure acting on the piston skirt from the cylinder 10a can also be reduced, so that friction can be reduced.

  FIG. 8 is a view of the notch 10b when viewed from the side of the engine.

  As shown in FIG. 8, the four notches 10b provided for each cylinder 10a are arranged on the locus of the counterweight 2c, and the width of the notch 10b is larger than the width of the counterweight 2c. Thereby, the function of the counterweight escape can be added to the notch 10b. Thereby, since the turning radius of the counterweight 2c can be increased, the reciprocating inertia force of the multi-link engine in which the mass of the main motion mechanism increases as compared with the single-link engine can be reduced.

  According to this embodiment described above, the length of the first cap bolt 41 is extended to the lower end position of the cylinder 10a. As a result, the fastening force between the cylinder block 10 and the crankshaft cap 20 increases, so that opening of the mouth can be prevented.

  Further, four notches 10b were formed in the cylinder block 10 at the lower end of the cylinder 10a. Since the notch 10b can reduce the tensile load of the first cap bolt 41, the amount of deformation of the cylinder bo 10a can be reduced. As a result, the surface pressure acting on the piston skirt from the cylinder 10a can be reduced, and the friction can be reduced.

  Further, the width of the notch 10b is made larger than the width of the counterweight 2c. Thereby, since the turning radius of the counterweight 2c can be increased, the reciprocating inertia force of the multi-link engine that increases the mass of the main motion mechanism can be reduced.

  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, in this embodiment, the four notches 10b are provided for each cylinder 10a, but it may be provided only in the vicinity of the bolt hole 41a corresponding to the first cap bolt 41.

It is a schematic block diagram of the multilink type engine which can change a compression ratio. It is the schematic of the support structure of a crankshaft and a control shaft. It is a figure explaining the compression ratio change method of a multi-link type engine. It is the figure which showed the piston stroke characteristic of a multilink type engine, and the piston stroke characteristic of a single link type engine. It is the figure which showed typically the downward load which acts on the crankshaft bearing part of a single link type engine and a multilink type engine. It is the schematic which showed the 1st cap bolt, the 2nd cap bolt, and the 3rd cap bolt which are screwed together in a cylinder block. It is the principal part enlarged view of the bottom view and bottom view of a cylinder block. It is a figure when a notch is seen from the engine side.

Explanation of symbols

1 Multi-link engine 2 Crankshaft 2a Crank journal (main shaft part)
2b Crankpin 2c Counterweight 3 Control shaft 10 Cylinder block 10a Cylinder 10b Notch 11 Upper link 12 Lower link 13 Control link 14 Piston 15 Piston pin 20 Crankshaft cap (crankshaft main bearing cap)
41 First cap bolt (fastening bolt)

Claims (3)

An upper link having one end connected to the piston via a piston pin;
A lower link connected to the other end of the upper link and a crank pin of the crankshaft;
A control shaft disposed substantially parallel to the crankshaft;
A control link having one end pivotably coupled to the control shaft and the other end coupled to the lower link;
A multi-link engine bearing structure comprising:
A crankshaft main bearing cap that supports the main shaft portion of the crankshaft with a cylinder block;
The crankshaft main bearing cap is disposed on the opposite side of the control shaft with respect to the center of the crankshaft and screwed into the cylinder block until the tip is substantially the same height as the lower end of the cylinder. A fastening bolt to be fastened to the cylinder block;
A bearing structure for a multi-link engine, comprising: 2. The multi-link engine bearing structure according to claim 1, wherein the cylinder block includes a notch for reducing a tensile load from the fastening bolt around a lower end portion of the cylinder. The bearing structure for a multi-link engine according to claim 2, wherein the notch is provided on a locus of a counterweight of the crankshaft, and a width of the notch is larger than a width of the counterweight. .

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