JP2015094238A - Holder structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holder structure of an internal combustion engine in which a holder can be located in a stable state.SOLUTION: A holder structure 4 of an internal combustion engine 1 includes: a rocker arm 42 of the internal combustion engine 1; a rocker shaft 43 for pivotally supplying the rocker arm 42; and a holder body 41 for holding the rocker shaft 43. The holder body 41 has an insertion cylinder 41a into which a spark plug is inserted, and a contact surface 41b which is formed on a top of the insertion cylinder 41a and with which a cylinder-head cover HC is made into contact. The rocker shaft 43 is arranged below the contact surface 41b in a projection direction in a cylinder axial direction.

Description

  The present invention relates to a valve train structure for an internal combustion engine, and more particularly to a holder structure for an internal combustion engine that includes a rocker arm of the internal combustion engine, a rocker shaft that pivotally supports the rocker arm, and a holder body that holds the rocker shaft.

  For example, Patent Document 1 discloses an internal combustion engine holder structure (cam carrier) that includes a rocker shaft that supports an intake rocker arm and an exhaust rocker arm, and a bearing that supports each camshaft. It is disclosed.

Japanese Patent No. 4651579

However, in the holder structure of the conventional internal combustion engine described in Patent Document 1, since the holder main body is fixed to the cylinder head only by the fastening bolt, a fastening bolt is used to firmly fix the holder main body to the cylinder head. There is a problem that a strong fastening is necessary.
In addition, the holder structure has a plug tube (collar) installed in the spark plug insertion part through which the ignition coil is inserted, so the position of the plug tube must be aligned, so there are many parts and assembly steps. There is a problem that the assembling property is bad.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a holder structure for an internal combustion engine that can be installed in a stable state.

  A holder structure for an internal combustion engine according to the present invention is a holder structure for an internal combustion engine comprising a rocker arm of the internal combustion engine, a rocker shaft that pivotally supports the rocker arm, and a holder body that holds the rocker shaft. The holder body has an insertion tube portion into which the spark plug is inserted, and an abutting surface formed on the upper surface of the insertion tube portion with which the head cover abuts, and the rocker shaft is formed on the abutting surface. It is arranged at a position below the projection in the cylinder axis direction.

According to such a configuration, the holder structure of the internal combustion engine has the head cover abutting on the contact surface of the upper surface of the insertion tube portion of the holder body into which the ignition plug is inserted, so that the insertion tube portion is supported. The main body can be firmly installed on the internal combustion engine main body in a stable state, and the holder main body can be reinforced. For this reason, even if a load is applied from the rocker shaft, the holder structure can reinforce the rocker shaft in a stable state since the periphery of the insertion tube portion supported by the head cover is reinforced.
Further, the rocker shaft is disposed at a position below the projection of the abutting surface in the cylinder axis direction, so that the base end portion of the rocker shaft is formed to extend to a position overlapping the insertion tube portion in plan view. The base end portion can be firmly held.

  The holder body is provided with a plurality of rocker arms and a plurality of rocker shafts corresponding to the rocker arms, and the plurality of rocker shafts are arranged between the plurality of rocker shafts in a plan view. It is preferable that a part of the insertion tube portion is provided overlapping.

  According to such a configuration, the plurality of rocker shafts provided in the holder main body are arranged so that a part of the insertion tube portion overlaps between the plurality of rocker shafts in plan view. Since it can install efficiently in the position which mutually adjoined, the whole holder main body can be reduced in size. Moreover, the holder main body can suppress the load added from a rocker shaft in the whole insertion cylinder part.

  Moreover, it is preferable that the insertion hole which inserts the said rocker shaft is formed in the said holder main body in the shape of a bag path.

  According to such a configuration, the holder body has the insertion hole for the rocker shaft formed in the shape of a bag path, so that the oil passage member plugs the back end of the insertion hole without using an oil stopper member such as a steel ball. Can be used as

  The holder body is preferably configured separately from the cam holder that pivotally supports the camshaft, and the cam holder is provided on the side of the holder body.

  According to such a configuration, the holder main body is configured separately from the cam holder that pivotally supports the camshaft, so that the cam holder is not affected when the holder main body is assembled to the cylinder head. Work can be done easily, and assembly is good.

  The present invention can provide a holder structure for an internal combustion engine that can be installed in a stable state on a cylinder head.

It is a principal part schematic perspective view which shows the holder structure of the internal combustion engine which concerns on embodiment of this invention. It is a schematic top view of the cylinder head which shows the installation state of a holder structure, and shows the state which removed the cam cap and the cam shaft. It is the perspective view which looked at the holder structure from diagonally upward. It is the perspective view which looked at the holder structure from diagonally downward. It is a disassembled perspective view of a holder structure. It is a top view of the holder structure which has a partial cross section. It is a principal part expanded bottom view of a holder structure. It is an AA line direction expanded sectional view of FIG. FIG. 8 is an enlarged cross-sectional view taken along line BB in FIG. 7.

  With reference to FIGS. 1-9, the holder structure 4 of the internal combustion engine 1 which concerns on embodiment of this invention is demonstrated. In the description of the embodiment, the vertical direction is the cylinder axis direction, the longitudinal direction of the cylinder head 2 along the axis of the camshaft 3 is the front-rear direction, and the short direction of the cylinder head 2 is the left-right direction.

≪Internal combustion engine≫
As shown in FIG. 1, the internal combustion engine 1 is a multi-cylinder (in-line 3-cylinder) four-cycle engine. Are provided in parallel along the front-rear direction. As shown in FIG. 2, the internal combustion engine 1 includes, for example, three holder structures 4 arranged in series in the front-rear direction of the cylinder head 2 (see FIG. 2).

≪Cylinder head≫
As shown in FIGS. 1 and 2, the cylinder head 2 forms a top portion of a combustion chamber (not shown) and is a part of an engine body to which an intake / exhaust system (not shown) of the internal combustion engine 1 is attached. Below the cylinder head 2, cylinders (not shown) are arranged at predetermined intervals in the front-rear direction.

≪Camshaft≫
As shown in FIG. 1, the camshaft 3 is a shaft having a plurality of cam pieces 3a for opening and closing an intake valve 71 for performing intake and exhaust of the combustion chamber and an exhaust valve 72. The camshaft 3 includes an intake camshaft 31 and an exhaust camshaft 32.
The intake camshaft 31 and the exhaust camshaft 32 are rotatably supported on the cylinder head 2 by four cam holders 5 (first to fourth cam holders 5A, 5B, 5C, 5D), respectively.

≪Cam holder≫
As shown in FIG. 1, the cam holder 5 is a bearing member that supports each camshaft 3 (the intake camshaft 31 and the exhaust camshaft 32). The cam holder 5 includes a holder base 51 formed integrally with the cylinder head 2, a cam cap 52 placed on the holder base 51, and a cap fixing bolt 53 for fastening the cam cap 52 to the holder base 51. , Mainly consists of. The cam holders 5 are arranged on the upper side of the cylinder head 2 along the intake camshaft 31 and the exhaust camshaft 32 in the first to fourth cam holders 5A, 5B, 5C arranged in two rows at appropriate intervals in the axial direction. Consists of 5D. The cam holder 5 is configured separately from the holder structure 4 and is provided on the left and right sides of the holder structure 4.
The cam cap 5 </ b> Aa of the first cam holder 5 </ b> A disposed on the most front side is fixed to a holder base 2 a formed at the front end on the cylinder head 2, with the intake side and the exhaust side formed integrally on the left and right. . The cam cap 5Aa is provided with a pair of left and right OVC valve holders 5Ab and 5Ac. The first cam holder 5A rotatably supports the front end portions of the left and right intake camshafts 31 and the exhaust camshaft 32.
Three holders, a second cam holder 5B, a third cam holder 5C, and a fourth cam holder 5D, are arranged in two rows on the left and right sides of the first cam holder 5A. Holder structures 4 are respectively arranged between the left and right second cam holders 5B and 5B, between the third cam holders 5C and 5C, and between the fourth cam holders 5D and 5D. The second to fourth cam holders 5B, 5C, 5D are respectively provided on the left and right of the center of each cylinder (not shown).

≪Holder structure≫
As shown in FIGS. 3 to 5, the holder structure 4 mainly has a function of transmitting the motion of the cam piece 3 a to the intake valve 71 and the exhaust valve 72 (see FIG. 1). The holder structure 4 is provided for each cylinder. The holder structure 4 includes a holder main body 41 mounted on the cylinder head 2, a plurality of rocker arms 42 pivotally supported by the holder main body 41, and a pivotal support for the rocker arms 42 to the holder main body 41. A rocker shaft 43, a holder fastening bolt 44 for fixing the holder main body 41 to the cylinder head 2, and a rocker shaft fixing bolt 45 for fixing the rocker shaft 43 to the holder main body 41 are provided.

<Holder body>
As shown in FIGS. 3 and 4, the holder main body 41 is a member for holding the rocker shaft 43. The holder main body 41 is configured in a substantially H shape (see FIG. 6) in plan view. A cylindrical insertion tube portion 41a is provided at the center of the holder main body 41, and bolt insertion holes 41e are provided at the protruding four boss portions. In addition, the holder body 41 includes a contact surface 41b, an insertion hole 41c, a notch groove 41d, an oil passage 41f, an annular groove 41g, a semicircular groove portion 41h, a hemispherical convex portion 41i, and an upper female screw portion. 41j, the installation part 41k, the notch part 41m, and the internal thread part 41n are formed. Hereinafter, each of these components will be described in detail.

As shown in FIGS. 3 and 4, the insertion tube portion 41 a is a portion into which a spark plug (not shown) is inserted. The insertion tube portion 41a is formed to protrude in a cylindrical shape upward from the center portion of the holder main body 41 so that the upper end surface thereof is in contact with the inner surface (back surface) of the head cover HC (see FIG. 8). A contact surface 41b and an annular groove 41g formed at the radial center of the contact surface 41b are formed on the upper end surface of the insertion tube portion 41a.
The contact surface 41b is a portion that contacts the inner surface of the head cover HC (see FIG. 8), and is formed by the upper end surface of the insertion tube portion 41a.
The annular groove 41g is a groove into which an O-ring that contacts the head cover HC (see FIG. 8) is inserted, and is formed on the contact surface 41b. For this reason, the space between the contact surface 41b and the head cover HC (see FIG. 8) is sealed by an O-ring.

  As shown in FIG. 6, the insertion hole 41c is a hole into which the rocker shaft 43 is inserted. The insertion hole 41c is composed of four horizontal holes formed in the front-rear direction from the left and right two locations near the center of the front end surface and the rear end surface of the holder body 41 to the vicinity of the lower portion of the insertion cylinder portion 41a (FIGS. 4 and FIG. 5). The insertion hole 41 c has a bag path shape (bottomed shape) formed with only one end opened and the other end closed within the holder main body 41. As shown in FIG. 5, a semicircular groove portion 41 h that is formed in a semicircular groove shape in a longitudinal sectional view is continuously formed on the opening end side of the insertion hole 41 c.

The notch groove 41d is a groove into which the base end portion of the rocker arm 42 is inserted in a swingable manner. The cutout groove 41d is a recess-shaped groove extending in the left-right direction from the front side and the rear side close to the outer periphery of the insertion tube portion 41a in plan view in the holder body 41. The cutout grooves 41d are formed from the left and right sides of the installation portion 41k formed in the front center portion and the rear center portion of the insertion tube portion 41a in plan view to the left and right ends of the holder body 41, respectively. It is formed symmetrically. The cutout groove 41d and the insertion hole 41c are arranged so as to cross each other. Thereby, when the rocker shaft 43 to be described later is inserted into the insertion hole 41c, the rocker shaft 43 crosses the notch groove 41d.
As shown in FIG. 4, the bolt insertion holes 41 e are holes into which the holder fastening bolts 44 that are fastened to the cylinder head 2 are inserted, and are formed at four locations on the front, rear, left and right ends of the holder body 41.
The oil passage 41f and the like will be described later.

  As shown in FIG. 3, the hemispherical convex portion 41 i is formed in a state in which it swells in a substantially dome shape from the upper surface of the holder body 41. The hemispherical convex portion 41i is provided above the semicircular groove portion 41h. Inside the hemispherical convex portion 41i, a female screw portion 41n (see FIG. 5) is drilled upward from the semicircular groove portion 41h. Two hemispherical convex portions 41 i are formed between the bolt insertion holes 41 e and 41 e formed at the left and right end portions (four corners) on the front side and the rear side of the holder body 41.

As shown in FIGS. 3 and 6, the upper female screw portion 41j is a boss portion into which a bolt for fixing the head cover HC (see FIG. 8) and the holder main body 41 is screwed. The upper female screw portion 41j is formed at approximately the center position in the left-right direction at two locations before and after the insertion tube portion 41a. The upper part of the upper female screw part 41j is formed in a cylindrical shape and protrudes from the upper surface of the holder body 41. A female thread is formed in the hollow portion of the upper female thread portion 41j. The upper surface of the upper female screw portion 41j is formed at the same height as the upper surface of the insertion tube portion 41a.
The front upper female thread portion 41j is slightly on the right hemispherical convex portion 41i side at the center portion between the left hemispherical convex portion 41i, the right hemispherical convex portion 41i, and the installation portion 41k described later. It is formed at a close position.
The rear upper female thread portion 41j slightly approaches the left hemispherical convex portion 41i side at the central portion between the left hemispherical convex portion 41i, the right hemispherical convex portion 41i, and the installation portion 41k. It is formed in the position.

As shown in FIG. 6, the erection part 41k is a reinforcing rib erected between the upper female thread part 41j and the insertion cylinder part 41a. The front installation portion 41k is formed at a position slightly shifted to the right side from the center line in the front-rear direction of the insertion tube portion 41a. The rear installation portion 41k is formed at a position slightly shifted to the left side from the center line in the front-rear direction of the insertion tube portion 41a.
As shown in FIG. 5, the notch portion 41 m is a portion in which a notch is formed between the left and right boss portions in which the bolt insertion holes 41 e of the holder fastening bolt 44 are formed at the front end portion and the rear end portion of the holder main body 41. . The head of the rocker shaft fixing bolt 45 is disposed in the notch 41m.
The female thread portion 41n is a portion to which the rocker shaft fixing bolt 45 is screwed. The female screw portion 41n is a bottomed screw hole provided in the hemispherical convex portion 41i, and opens into the semicircular groove portion 41h.

<Rocker arm>
As shown in FIG. 9, the rocker arm 42 is a swinging member that swings around the rocker shaft 43 as a fulcrum and is driven to open and close the intake valve 71 and the exhaust valve 72 when pressed by the cam piece 3 a. As shown in FIGS. 3 and 4, the rocker arm 42 includes, for example, two sets of intake rocker arms 42A disposed on the right side and two sets of exhaust rocker arms 42B disposed on the left side. ing.

  As shown in FIG. 9, each rocker arm 42 has an arm main body 42a, a pressed portion 42b with which the cam piece 3a (see FIG. 1) abuts, a shaft hole 42c into which the rocker shaft 43 is inserted, and lubricating oil. An oil passage 42d that flows and a valve pressing portion 42e that presses the intake valve 71 and the exhaust valve 72 are provided. The base end portion of the rocker arm 42 is inserted into the cutout groove 41 d of the holder main body 41 so as to be swingable, and is pivotally supported by the rocker shaft 43. The oil passage 42d will be described in detail later.

The arm main body 42a is mainly an arm member having a shaft hole 42c at the base end portion, a pressed portion 42b above the tip end portion, and a valve pressing portion 42e below the tip end portion.
The pressed part 42b is a pressed part to be pressed by the cam piece 3a (see FIG. 1). The pressed portion 42b is made of a wear-resistant metal integrally formed with the arm body 42a. The pressed part 42b is formed in a curved shape at the upper end of the arm body 42a.

The shaft hole 42c is arranged on the same axis as the insertion hole 41c formed in the front-rear direction, and is formed so as to be orthogonal to the oil passage 42d.
The valve pressing portion 42e is formed in a shape that rises in a curved shape from the lower end to the lower end of the arm main body 42a.

<Rocker shaft>
As shown in FIG. 5, the rocker shaft 43 is an axis that serves as a fulcrum of the rocker arm 42 that performs a swinging motion. The rocker shaft 43 has a semi-cylindrical shape in which a cylinder is divided in half in the axial direction from one end to a substantially central position in the longitudinal direction, and a bottomed cylindrical shape is formed from the other end to a substantially central position in the longitudinal direction. In the semi-cylindrical portion of the rocker shaft 43, a flat seat surface 43b is provided on the lower side, and a bolt insertion hole 43a penetrating from the seat surface 43b in the radial direction of the rocker shaft 43 is formed. Oil passages 43 c and 43 d are formed in the bottomed cylindrical portion of the rocker shaft 43. The oil passages 43c and 43d will be described in detail later.

  The rocker shaft 43 is inserted into a pair of insertion holes 41 c formed on the front surface and the rear surface of the holder body 41, and is fixed to the holder body 41 by rocker shaft fixing bolts 45. In this state, as shown in FIGS. 6 and 8, the end 43e on the insertion tube portion 41a side of the rocker shaft 43 is arranged to extend to a position below the projection in the cylinder axis direction of the contact surface 41b. A part of the cylinder part 41a is provided overlappingly. The bottomed cylindrical portion of the rocker shaft 43 is inserted into the shaft hole 42c of the rocker arm 42 inside the notch groove 41d.

The bolt insertion hole 43 a is formed at the tip end portion of each rocker shaft 43 in the vertical direction, and is arranged on the same axis as the female thread portion 41 n of the holder main body 41.
The seat surface 43b is formed in a semicircular cutout in a sectional view of the lower side of the portion where the bolt insertion hole 43a is formed at the tip of each columnar rocker shaft 43.

<Holder fastening bolt>
As shown in FIG. 3, the holder fastening bolt 44 is a fastener for fixing the holder main body 41 to the cylinder head 2. The holder fastening bolts 44 are respectively inserted into bolt insertion holes 41e (see FIG. 5) formed at four positions on the front and rear sides and the left and right sides of the holder main body 41.

<Rocker shaft fixing bolt>
The rocker shaft fixing bolt 45 is a fastener for fixing the rocker shaft 43 inserted into each insertion hole 41 c to the holder main body 41. The head of the rocker shaft fixing bolt 45 is disposed in the notch 41 m in the holder main body 41. For this reason, the rocker shaft fixing bolt 45 enables the entire length to be shortened and allows the rocker shaft fixing bolt 45 to be attached to the seating surface 43b.

<Oil channel>
As shown in FIG. 8, the oil passage 41f of the holder body 41 is a passage through which lubricating oil flows. The oil passage 41f communicates the recess 41o (see FIGS. 4 and 5) having a certain depth formed on the lower surface of the holder main body 41 and before and after the insertion tube portion 41a, and the recess 41o and the insertion hole 41c. Thus, the vertical hole 41p extended in the up-down direction is formed continuously.
As shown in FIGS. 4 and 5, the concave portion 41 o is composed of a pair of front and rear substantially arc-shaped grooves formed on the front side and the rear side of the insertion tube portion 41 a as viewed from the bottom. When the holder body 41 is connected to the upper surface of the cylinder head 2, the recess 41 o defines an oil path with the upper surface of the cylinder head 2.
The vertical holes 41p are respectively formed at two locations on the left and right end portions of the inner bottom of each recess 41o. That is, a total of four vertical holes 41 p are formed corresponding to the number of rocker shafts 43.

  As shown in FIG. 8, the vertical hole 41p is formed at a position between the insertion tube portion 41a and the cutout groove 41d in a vertical cross-sectional view. Further, the vertical hole 41p communicates with the space between the bottom of the insertion hole 41c and the end 43e of the rocker shaft 43 on the insertion cylinder part 41a side of the insertion hole 41c. This space forms part of an oil passage through which the lubricating oil flows.

  As shown in FIG. 8, the rocker shaft 43 includes a bottomed oil passage 43d drilled in the axial direction of the rocker shaft 43 from an end portion 43e on the insertion tube portion 41a side of the rocker shaft 43, and the oil passage 43d. To the outer peripheral surface of the rocker shaft 43. The oil passage 43d communicates with the space between the bottom of the insertion hole 41c and the end surface of the rocker shaft 43 on the insertion tube portion 41a side. The oil passage 43c communicates with a shaft hole inner groove portion 42f formed in the shaft hole 42c of the rocker arm 42 at a position where the notch groove 41d is formed.

  As shown in FIG. 9, the rocker arm 42 has an oil passage 42d that feeds lubricating oil through the arm main body 42a toward the pressed portion 42b. The oil passage 42d includes the shaft hole groove 42f, the discharge port 42h that opens near the pressed portion 42b, and the arm main body flow path 42g that connects the shaft hole groove 42f and the discharge port 42h. Is formed.

  In this way, the oil passage 41f has an upstream side communicating with an oil passage (not shown) of the cylinder head 2 provided on the lower surface of the holder body 41, and a downstream side extending from the recess 41o on the lower surface of the holder body 41 to the vertical hole 41p. The oil passage 42d of the rocker arm 42 communicates with the oil passage 43d and 43c of the rocker shaft 43 through the insertion hole 41c. For this reason, the lubricating oil sent into the holder main body 41 from the oil passage 41f passes through the oil passages 43d and 43c of the rocker shaft 43 and the oil passage 42d of the rocker arm 42 as shown in FIG. It flows out from the discharge port 42h on the top surface on the front end side and lubricates the contact portion between the rocker arm 42 and the cam piece 3a.

≪Action≫
Next, the operation of the holder structure 4 of the internal combustion engine 1 according to the embodiment of the present invention will be described with reference to FIGS.

First, the assembly of the holder structure 4 will be described.
As shown in FIG. 5, when assembling the holder structure 4, first, the base end side where the shaft hole 42 c of each rocker arm 42 is formed is inserted into the notch groove 41 d. Next, the rocker shaft 43 is inserted into the insertion hole 41 c, and the bottomed cylindrical portion of the rocker shaft 43 is inserted into the shaft hole 42 c of the rocker arm 42. The rocker shaft fixing bolt 45 is inserted into the bolt insertion hole 43 a of the rocker shaft 43, and the rocker shaft fixing bolt 45 is screwed to the female thread portion 41 n of the holder body 41.

  Thereby, the rocker arm 42 is attached to the holder main body 41 so as to be rotatable about the rocker shaft 43. At the same time, the rocker shaft 43 is fixed to the holder body 41. Then, as shown in FIGS. 8 and 9, the rocker arm 42 is pivotally supported by the holder main body 41 in a rotatable state by a rocker shaft 43 fixed to the holder main body 41 by a rocker shaft fixing bolt 45. . Thus, since the two members are fastened together with one rocker shaft fixing bolt 45, the number of parts and the number of assembling steps are small, so that they can be attached efficiently.

  The rocker shaft 43 is disposed at a position below the projection of the abutting surface 41b of the insertion tube portion 41a in the cylinder axial direction, so that the base end portion 43e of the rocker shaft 43 is seen through the insertion tube portion 41a in plan view. The base end portion 43e can be firmly held by extending it to a position where it overlaps with the base end portion 43e.

  When inserting each member into the holder main body 41 and performing the bolting operation, as shown in FIG. 5, the assembly work can be performed in advance as the holder structure 4 without the cylinder head 2 or the like around it. Since it does not come into contact with other members, the assembly work is easy to perform.

  At the same time, a lubricating oil supply oil passage is formed in the holder structure 4 shown in FIGS. That is, the lubricating oil supplied from the cylinder head 2 side flows from the oil passage 41 f on the bottom surface of the holder body 41 to the oil passage 42 d of the rocker arm 42 through the insertion hole 41 c and the oil passages 43 d and 43 c of the rocker shaft 43. The portion to be pressed 42b of the rocker arm 42 and the cam piece 3a are supplied from the discharge port 42h on the upper surface of the arm body 42a.

  Each holder structure 4 assembled as shown in FIG. 3 is attached to each cylinder (not shown) in a row on the cylinder head 2 by four holder fastening bolts 44 on the front, rear, left and right as shown in FIG. . Each holder structure 4 is securely mounted by placing a head cover HC (see FIG. 8) on the cylinder head 2 and screwing bolts from the head cover HC side to upper female screw portions 41j at the front and rear portions of each holder body 41. And can be attached to the internal combustion engine 1.

  At that time, the contact surface 41b on the upper surface of the insertion tube portion 41a of the holder main body 41 is installed in a state in which the head cover HC (see FIG. 8) is in contact, so that a vertical load applied to the holder structure 4 from above is applied. Even the contact surface 41b can be received. For this reason, the holder structure 4 can be firmly installed on the cylinder head 2 in a stable state, and the holder main body 41 can be reinforced. Even if a load is applied from the rocker arm 42 and the rocker shaft 43, the holder main body 41 is reinforced around the insertion tube portion 41a supported by the head cover HC (see FIG. 8). 43 can be held in a stable state.

  Further, the holder structure 4 has the insertion tube portion 41a for installing the spark plug between the front and rear rocker arms 42 and the front and rear rocker shafts 43, so that these members are positioned close to each other. Since it can install efficiently, the holder structure 4 whole can be reduced in size. For this reason, when the holder structure 4 is attached to the cylinder head 2, it does not take an installation space, so that attachment to the cylinder head 2 is easy.

Next, the operation of the rocker arm 42 provided in the holder structure 4 will be described.
The internal combustion engine 1 shown in FIG. 1 is started, and rotation from a crankshaft (not shown) is transmitted to the intake camshaft 31 and the exhaust camshaft 32 via a chain transmission mechanism. As shown in FIG. 9, the cam piece 3a includes an intake valve 71 and an exhaust valve via the intake rocker arm 42A and the exhaust rocker arm 42B when the intake camshaft 31 and the exhaust camshaft 32 rotate. 72 is driven.

  As shown in FIGS. 8 and 9, the contact portion where the cam piece 3a contacts the intake rocker arm 42A and the exhaust rocker arm 42B is lubricated by the lubricating oil discharged from the discharge port 42h. Can be reduced. Therefore, the intake valve 71 and the exhaust valve 72 can be operated favorably by smoothing the movement of the intake rocker arm 42A and the exhaust rocker arm 42B. Therefore, the holder structure 4 is suitable for the high-rotation internal combustion engine 1.

When the holder structure 4 needs to be replaced, the holder structure 4 as a whole, or the intake rocker arm 42A and the exhaust rocker arm 42B can be easily attached and removed for repair. The bearings of the cam holder 5 are all concentric by machining the bearing holes in a state where the members are assembled. For this reason, when the cam holder 5 and the holder structure 4 are integrated, the bearing hole of the camshaft 3 is formed with all the members assembled once, and then the members are removed and the valve and camshaft 3 are assembled. Must be reattached. On the other hand, since the holder structure 4 of the internal combustion engine 1 of the present embodiment is separate from the cam holder 5, only the cam holder 5 can be easily processed without attaching the holder structure 4 to the cylinder head 2.
Further, since the internal combustion engine 1 can be easily attached and detached to a predetermined position by the holder fastening bolt 44 because the holder structure 4 is separate from the cam holder 5, adjustment of the intake valve 71 and the exhaust valve 72, Since other parts can be replaced independently, adjustment work and part mounting work are easy to perform.

  As described above, the holder structure 4 of the internal combustion engine 1 according to the embodiment of the present invention can install the holder structure 4 in the internal combustion engine 1 in a stable state, and also includes an intake rocker arm 42A attached to the holder body 41 and The holder structure 4 in which the movement of the exhaust rocker arm 42B is smooth and compact can be provided.

  The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.

  For example, the shape of the oil passage 41f of the holder main body 41 described in the above embodiment only needs to supply the lubricating oil from the cylinder head 2 to the oil passage 42d of the rocker arm 42 via the rocker shaft 43. You may change suitably.

  In the above-described embodiment, an inline three-cylinder engine has been described as an example of the internal combustion engine 1, but the present invention can also be applied to a V-type engine. In this case, the vertical direction is the straight direction, and the cylinder axis direction is inclined by a predetermined angle with respect to the vertical direction.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Cam shaft 4 Holder structure 5 Cam holder 41 Holder main body 41a Insertion cylinder part 41b Contact surface 41c Insertion hole 42 Rocker arm 43 Rocker shaft 43a Insertion cylinder part HC Head cover

Claims (4)

A holder structure of an internal combustion engine comprising a rocker arm of the internal combustion engine, a rocker shaft that pivotally supports the rocker arm, and a holder body that holds the rocker shaft,
The holder body includes an insertion tube portion into which a spark plug is inserted,
A contact surface that is formed on the top surface of the insertion tube portion and contacts the head cover,
The holder structure for an internal combustion engine, wherein the rocker shaft is disposed at a position below the projection in the cylinder axis direction of the contact surface. The holder body is provided with a plurality of rocker arms and a plurality of rocker shafts corresponding to the rocker arms,
2. The holder structure for an internal combustion engine according to claim 1, wherein the plurality of rocker shafts are provided with a part of the insertion tube portion overlapping between the plurality of rocker shafts in a plan view.   The holder structure for an internal combustion engine according to claim 2, wherein an insertion hole for inserting the rocker shaft is formed in the holder main body in a bag path shape.   The said holder main body is comprised separately from the cam holder which pivotally supports a cam shaft, The said cam holder is provided in the side of the said holder main body, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. The holder structure of the internal combustion engine according to the item.

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