JP5752571B2 - Camshaft positioning structure - Google Patents

Description

  The present invention relates to a camshaft positioning structure for phase alignment and the like.

  Conventionally, some DOHC engines are provided with a camshaft positioning structure for proper valve opening / closing timing (phase). For example, when the camshaft is linked via a sprocket connected to the crankshaft, a pin fixing hole is formed on each of the end face of the gear fixed to the camshaft and the end face of the sprocket, and a positioning pin is provided in each pin fixing hole. Is pressed to position the sprocket and the gear, and the gear and the camshaft are positioned by the half moon key. In this way, there is one in which the positioning of the sprocket and the camshaft is performed with the positioning pin and the half moon key (for example, see Patent Document 1).

Japanese Patent No. 3978825

  In the camshaft positioning structure of Patent Document 1, as described above, for positioning the gear and the sprocket positioned on the camshaft with the half moon key, the positioning pin is set to each pin fixing hole in the axial direction of the camshaft. Press fit. Therefore, the press-in operation of the positioning pin and the operation of removing it after the positioning are performed from the side of the cylinder head that is the axial direction of the camshaft. When working with the upper surface of the cylinder head up, there is a problem that the workability is poor because the shape is viewed from the side.

  Also, in the press-fitting work of the positioning pin, for example, by looking into the pin fixing hole of the sprocket and visually recognizing the pin fixing hole of the gear, the pin fixing hole of the sprocket and the pin fixing hole of the gear are aligned, and in this state It is conceivable to press-fit the positioning pins. However, during the press-fitting operation of the positioning pin after the pin fixing holes are aligned, the pin fixing hole of the gear on the back side cannot be visually observed. Therefore, if the camshaft rotates when the positioning pin is inserted into the pin fixing hole of the sprocket, it must be done from the position where the positioning pin is removed and the pin fixing holes are aligned again, which complicates the work. There is.

In order to solve such problems and improve the workability in positioning the camshaft, in the present invention, the camshaft (30/37) provided in the cylinder head (1) of the engine is positioned. And a pin insertion hole (44) provided on the outer peripheral surface of the camshaft, and the camshaft positioning structure is inserted into the pin insertion hole and is removed after the operation in the positioning state of the camshaft is completed. A positioning pin (45), a housing (28, 36) of a bearing that supports the camshaft, and a housing that is located on a side away from the cylinder head with respect to the camshaft; A pin engaging portion (42) that engages with the positioning pin inserted into the pin insertion hole in the rotational direction of the camshaft. Have a, the pin engaging portion, was assumed to be formed in a U-shape which opens opposite side to the axial direction and the housing of the camshaft.

  According to this, the pin insertion hole provided in the gum shaft is provided in the housing of the bearing that supports the cam shaft because the pin engaging portion that engages with the positioning pin is provided on the side away from the cylinder head with respect to the cam shaft. The operation of inserting the positioning pin into the cylinder head can be performed by accessing from the opening side of the cylinder head. For example, when the cylinder head has a box shape and is placed in a flattened form on the work table to perform the pin insertion work, it can be performed from above and the work can be easily performed.

  In particular, the pin engaging portion (42) may be formed in a U-shape that opens in the axial direction of the camshaft. According to this, since the outer peripheral surface of the camshaft can be seen obliquely from the U-shaped outward opening of the pin engaging portion, the pin insertion hole can be easily visually recognized. For example, when a hole whose periphery is closed is formed in the projecting piece, it is necessary to visually recognize the pin insertion hole of the camshaft as if it is viewed from directly above, whereas the pin engaging portion is U-shaped. By doing so, the pin insertion hole can be seen from obliquely upward, so that visibility is improved and workability is further improved.

  The pin insertion hole (44) may be provided in the solid portion (49) of the camshaft. According to this, the strength reduction by providing a pin insertion hole can be suppressed.

  As described above, according to the present invention, the protruding piece having the pin engaging portion that engages with the positioning pin inserted into the camshaft is provided on the upper side of the engine with respect to the camshaft of the bearing housing that supports the camshaft. Therefore, the operation of inserting the positioning pin into the pin insertion hole provided in the camshaft can be performed by accessing from above the cylinder head, and the pin insertion operation can be easily performed.

It is a perspective view of a cylinder head of an engine to which the present invention is applied. It is a figure which shows the principal part of the valve mechanism of the intake side seen from the arrow II direction of FIG. It is the principal part enlarged plan view seen from the arrow III direction of FIG. It is sectional drawing seen along the arrow IV-IV line of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a cylinder head 1 of an in-line four-cylinder four-valve DOHC type gasoline direct injection engine that is an example of an engine to which the present invention is applied.

  As shown in FIG. 1, the cylinder head 1 has a substantially rectangular parallelepiped lower portion elongated in the left-right direction, and a box-shaped upper portion that is provided at the upper end of the lower portion and whose upper surface is opened in the drawing. . In the lower part of the cylinder head 1, there are four combustion chambers (not shown) recessed in the lower surface of the cylinder head 1, an exhaust port (not shown) extending forward from each combustion chamber, and a rear side from each combustion chamber. An intake port (not shown) that extends to the rear side surface of the cylinder head 1 is formed. On the front side surface of the cylinder head 1, a front end (downstream end) of the exhaust collecting chamber 2 formed so that the exhaust ports are gathered inside the lower portion of the cylinder head 1 is opened.

  In the upper part of the cylinder head 1, a front edge wall 11, a rear edge wall 12, a left edge wall 13 and a right edge wall 14 which are erected along the four sides of the lower part of the cylinder head 1 and an upper surface of the lower part are provided. A substantially rectangular parallelepiped box-shaped valve chamber 16 opening upward is formed by the bottom wall 15 formed. A head cover and a fuel injection pump (not shown) are fastened to the upper ends of the front edge wall 11, the rear edge wall 12, the left edge wall 13, and the right edge wall 14, and thereby the valve chamber 16 that receives the drive system is received by them. The top is covered. The bottom wall 15 of the cylinder head 1 is formed with a cylindrical plug insertion cylinder portion 17 into which a spark plug (not shown) is inserted, and an intake valve 18 and an exhaust valve 19 constituting a drive system are provided. An injector hole (not shown) is provided in which a non-injector is inserted.

  On the rear side of the bottom wall 15, a plurality of intake side shaft support portions 25 are integrally projected in the cylinder row direction. An intake side rocker shaft 26 is fixedly supported on the intake side shaft support portion 25. An intake side rocker arm 27 for driving the intake valve 18 in the valve opening direction is rotatably supported on the intake side rocker shaft 26. A semicircular recess is formed at the protruding end (upper end) of the intake shaft support 25, and an intake cam cap 28 constituting a housing of the bearing is fastened so as to cover the recess. The protruding end of the intake side shaft support portion 25 and the intake side cam cap 28 form an intake side camshaft bearing 29. An intake side camshaft 30 is rotatably supported by the intake side camshaft bearing 29.

  On the front side of the bottom wall 15, a plurality of exhaust side shaft support portions 32 are integrally projected. An exhaust side rocker shaft (not shown) is fixedly supported on the exhaust side shaft support portion 32, and an exhaust side rocker arm 34 to which an exhaust valve 19 is connected is rotatably supported on the exhaust side rocker shaft. A semicircular recess is formed at the protruding end (upper end) of the exhaust-side shaft support portion 32, and an exhaust-side cam cap 35 is fastened so as to cover the recess. The protruding end of the exhaust side shaft support portion 32 and the exhaust side cam cap 35 form an exhaust side cam shaft bearing 36. An exhaust side camshaft 37 is rotatably supported by the exhaust side camshaft bearing 36.

  The intake-side camshaft 30, the exhaust-side camshaft 37, the intake-side rocker shaft 26, and the exhaust-side rocker shaft each extend in the longitudinal direction (left-right direction) of the cylinder head 1. An intake side cam 38 that drives the intake side rocker arm 27 is formed on the intake side camshaft 30, and an exhaust side cam 39 that drives the exhaust side rocker arm 34 is formed on the exhaust side camshaft 37. The intake side camshaft 30 and the exhaust side camshaft 37 are rotated by a crankshaft (not shown) via a timing belt (chain) 51, for example.

  FIG. 2 is a view showing a main part of the valve mechanism on the intake side as seen from the direction of arrow II in FIG. In the present embodiment, the lift amount and the valve opening timing (phase) are controlled by dividing the intake valve 18 into a plurality of stages (for example, low and high speed) by three intake side cams 38. The three intake side cams 38 have a low speed cam and a high speed cam having different cam profiles, and are integrally provided on one intake side camshaft 30. Corresponding to the three intake side cams 38, the three intake side rocker arms 27 can rotate independently of each other and are provided in parallel. The intake-side rocker arm 27 selected according to the stage is cam-driven and rocked by the rotation of the intake-side cam 38 in the direction of arrow A in the figure, and the rocking motion is transmitted to the intake valve 18. Opens and closes.

  In the present embodiment, the cam profile of the exhaust side cam 39 is one type, and other cam driving procedures and the like are the same as those on the intake side, and detailed description thereof is omitted.

  2, the rocker arm shaft 26 is provided with three oil passages 41a, 41b, and 41c that extend in the axial direction and are parallel to each other. For example, the oil passage 41a communicates with one of the intake side rocker arms 27, the oil passage 41b communicates with the other one of the intake side rocker arms 27, and the remaining oil passage 41c is used as a lubricating oil passage. The switching of the three intake side rocker arms 27 is performed by reciprocating the connecting pins 42 provided so as to be movable between the intake side rocker arms 27 by switching the hydraulic pressure supply from the oil passages 41a and 41b. Since this structure is publicly known, detailed illustration and description thereof will be omitted. These cam structures constitute a drive system.

  3 is an enlarged plan view of a main part viewed from the direction of arrow III in FIG. 1, and FIG. 4 is a cross-sectional view viewed along the line IV-IV in FIG. 3 and 4 are not the same except for the main part.

  As shown in FIGS. 3 and 4, the intake-side cam cap 28 that constitutes a bearing that supports one end of the intake-side camshaft 30 in the axial direction (the right side in FIG. 3) extends in the axial direction of the camshaft 30. The projecting piece-shaped pin engaging portion 42 is integrally formed. The pin engaging portion 42 is located above the camshaft 30 in the drawing (on the side away from the cylinder head 1). As shown in FIG. 3, the pin engaging portion 42 is formed in a U shape that opens in the axial direction of the camshaft 30 and on the side opposite to the intake side cam cap 28 in plan view.

A pin insertion hole 44 having the same length as the U-shaped groove width b of the pin engaging portion 42 is opened on the outer peripheral surface of the intake side camshaft 30. The pin insertion hole 44 is formed in a radial direction perpendicular to the axis of the intake camshaft 30. A positioning pin 45 is inserted coaxially into the pin insertion hole 44 in a substantially press-fitted state. The positioning pin 45 protrudes a predetermined length across the pin engaging portion 42 (on the upper surface side of the cylinder head 1) in a completely inserted state into the pin insertion hole 44.

  When the positioning pin 45 is inserted into the pin insertion hole 44 and the positioning pin 45 and the pin engaging portion 42 are engaged, the intake side camshaft 30 is positioned in the rotational direction. The positioning is set according to the valve timing (phase alignment), and the valve opening timing of the intake valve 18 is adjusted, and the phase alignment is performed between the crankshaft pulley (not shown) in the temporarily fixed state. The timing belt 51 is hooked.

  In this positioning operation, the cylinder head 1 is placed on the work table with the opened surface of the box shape facing upward as shown in FIG. 1, whereby the positioning pin 45 is inserted into the pin insertion hole of the camshaft 30. When inserting into the shaft 44, the positioning pin 45 can be inserted into the camshaft 30 from above as shown by the arrow B in FIG. When the groove width b of the pin engaging portion 42 is the same as the diameter of the positioning pin 45, the positioning pin 45 can be guided and positioned with high accuracy. The relationship between the groove width b and the diameter of the positioning pin 45 may be set to a clearance fit tolerance so that the positioning pin 45 can be smoothly slidably contacted with the pin engaging portion 42.

  When the pin engaging portion is a through hole, the pin insertion hole 44 is visually recognized through the pin engaging portion from directly above. Therefore, if the intake camshaft 30 moves even a little after the positioning pin 45 is inserted into the pin engaging portion, it is necessary to insert it again, and the insertion work becomes complicated.

  On the other hand, since the pin engaging portion 42 is formed in a U-shape as described above, the pin insertion hole 44 can be viewed from obliquely upward as shown by an arrow C in FIG. . Since the positioning pin 45 can be inserted while visually recognizing the pin insertion hole 44, even if the intake side camshaft 30 moves after the positioning pin 45 is inserted into the pin engaging portion 42, the pin engaging portion 42 of the positioning pin 45. Thus, the positioning pin 45 can be easily inserted into the pin insertion hole 44. When the above phase alignment and timing belt 51 are finished, the positioning pin 45 is removed. Since the positioning pin 45 is inserted into the pin insertion hole 44 in a substantially press-fit state as described above, it does not easily fall off during the operation. And the positioning pin 45 can be easily pulled out after completion | finish of work.

  The intake side camshaft 30 has a fastening screw hole 47 of the cam pulley 46 coupled to the axial end surface on the intake side cam cap 28 side where the pin engaging portion 42 is provided, and the axial end surface on the opposite side. And an oil supply passage 48 drilled in the axial direction. A solid wall portion 49 is formed in a portion where the fastening screw hole 47 and the oil supply passage 48 are abutted, and a pin insertion hole 44 is provided in the wall portion 49. Since the pin insertion hole 44 is provided in the wall portion 49 that is a solid portion, a decrease in strength due to the provision of the pin insertion hole 44 can be suppressed. Further, it is not necessary to form the fastening screw hole 47 long, and the wall portion 49 is positioned in the vicinity of the intake side cam cap 28 on the axial end side of the intake side camshaft 30. The extension length of the pin engaging portion 42 extending from the end may be short, and an increase in weight can be suppressed.

  As shown in FIG. 3, the exhaust side camshaft 37 is also similar to the positioning structure in the intake side camshaft 30, and the same parts as those described above are denoted by the same reference numerals and detailed description thereof is omitted.

  Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to such embodiments so that those skilled in the art can easily understand, and departs from the spirit of the present invention. It is possible to change appropriately within the range not to be. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

1 Cylinder head 30 Intake camshaft (camshaft)
37 Exhaust side camshaft (camshaft)
28 Inlet cam cap (bearing housing)
36 Exhaust side cam cap (bearing housing)
45 Positioning pin 44 Pin insertion hole 42 Pin engaging part 49 Wall part (solid part)

Claims (2)

A camshaft positioning structure for positioning a camshaft provided in a cylinder head of an engine,
A pin insertion hole provided on the outer peripheral surface of the camshaft;
A positioning pin that is inserted into the pin insertion hole and pulled out after completion of the operation in the positioning state of the camshaft;
A bearing housing that supports the camshaft;
The camshaft is integrally formed with the housing so as to be located on the side away from the cylinder head with respect to the camshaft, and is engaged with the positioning pin inserted into the pin insertion hole in the rotation direction of the camshaft. It has a pin engagement portion to be,
The cam shaft positioning structure, wherein the pin engaging portion is formed in a U-shape that opens in an axial direction of the cam shaft and on a side opposite to the housing .   2. The camshaft positioning structure according to claim 1, wherein the pin insertion hole is provided in a solid portion of the camshaft.

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