JP2009215920A - Cylinder head structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder head structure of an internal combustion engine sufficiently reduced in weight while securing the rigidity to withstand the expansive-contractive deformation of a cylinder head by a combustion pressure in a combustion chamber. <P>SOLUTION: A fuel injection valve insertion boss part 26 is formed by extending an insertion hole 26h through each combustion chamber of the cylinder head from the generally center upward. Head bolt boss parts 27 are formed on the head outer peripheral part of the cylinder head. A seal surface 22s for sealing the valve cam chamber 24 of the cylinder head stores the head bolt boss part 27 therein. The areas near the fuel injection valve insertion boss part 26 and the head bolt boss parts 27 are alternately connected to each other on the opposite side of a camshaft supporting side where a camshaft 51 is supported. The cylinder head structure is formed in a recessed and projecting shape when viewed from above. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cylinder head structure for an internal combustion engine.

Generally, in an internal combustion engine, a cylinder head is fastened to a cylinder block with a head bolt, and the head bolt is disposed around the cylinder so as to surround the cylinder, and constitutes a top surface of a combustion chamber above the cylinder of the cylinder head. When the head bolt is fastened around the combustion chamber of the head bottom wall, the top surface of the combustion chamber where the combustion pressure is applied is pressed down.
However, when the combustion pressure is high, the cylinder head itself undergoes expansion deformation due to expansion pressure (combustion pressure) due to combustion, and various examples have been proposed in which expansion deformation of the cylinder head is suppressed as much as possible ( For example, see Patent Document 1).

JP 2000-230456 A

  The pressure of the combustion pressure acting on the top surface of the combustion chamber of the cylinder head acts to expand the portion constituting the top surface of the combustion chamber inside the fastening portion of the surrounding head bolt in the radial direction. Is high, it is conceivable to increase the thickness of the cylinder head, particularly the bottom wall of the head, but there is a problem that the weight increases.

  Therefore, in the cylinder head disclosed in Patent Document 1, the bolt bosses (head bolt bosses) of the head bolts are connected by ribs, and the bolt boss, the valve guide boss, and the valve guide boss. By providing ribs that connect the fuel injection valve housing bosses to each other, an attempt is made to avoid an increase in weight and ensure sufficient rigidity.

  In the cylinder head disclosed in Patent Document 1, the rib that connects the boss portions does not constitute the uppermost surface of the cylinder head that is the same as the sealing surface that is a mating surface with the head cover, and the rib is the uppermost surface of the cylinder head. The bosses are connected at a lower position.

When the combustion pressure acts on the top surface of the combustion chamber of the cylinder head, the cylinder head expands and deforms in the radial direction around the combustion chamber, and then contracts and deforms. Tries to stretch and deform the largest.
However, since the rib provided to ensure rigidity in the cylinder head of Patent Document 1 is not formed at the upper end portion of the cylinder head, it does not function to effectively suppress expansion / contraction deformation of the cylinder head.

Therefore, by forming a large number of ribs, the rigidity to withstand the expansion / contraction deformation of the cylinder head is ensured.
Therefore, the weight cannot be reduced while ensuring the necessary rigidity of the cylinder head.

  The present invention has been made in view of such points, and an object thereof is an internal combustion engine capable of sufficiently reducing the weight while ensuring rigidity to withstand expansion / contraction deformation of the cylinder head due to the combustion pressure of the combustion chamber. The cylinder head structure is provided.

  In order to achieve the above object, according to a first aspect of the present invention, a plurality of cylinders are arranged in series, and an intake side and an exhaust side are configured on opposite sides with respect to a plane including the cylinder axis of each cylinder, The camshaft that drives the valve and the exhaust valve on the exhaust side is arranged to be oriented in the cylinder arrangement direction so as to be biased to either the intake side or the exhaust side, and directly injects fuel into the combustion chamber at the top of each cylinder In a cylinder head structure of an internal combustion engine provided with a fuel injection valve, a fuel injection valve insertion boss for inserting the fuel injection valve penetrates an insertion hole upward from a substantially central position of each combustion chamber of the cylinder head. And a plurality of head bolt bosses through which a head bolt for fastening the cylinder head to the cylinder block passes are formed on the outer periphery of the head of the cylinder head. The sealing surface that is sealed together and seals the inner valve cam chamber accommodates the head bolt boss portion on the inner side, and is on the opposite side of the intake side and the exhaust side to the cam shaft support side on which the cam shaft is supported, The cylinder head structure of the internal combustion engine is formed by alternately connecting the fuel injection valve fitting boss portion and the vicinity of the head bolt boss portion to form an uneven shape in a top view.

  According to a second aspect of the present invention, in the cylinder head structure of the internal combustion engine according to the first aspect, the head bolt boss portion sandwiches each cylinder between the intake side outer edge portion and the exhaust side outer edge portion of the head outer peripheral portion. The cam shaft support side seal surface on which the cam shaft is supported on the intake side and the exhaust side is formed in a straight line along the head bolt boss portion formed in series. The seal surface opposite to the shaft support side has a recessed seal surface portion recessed toward the valve operating cam chamber at the fuel injection valve insertion boss portion, and an outer periphery curved outward along the head bolt boss portion. It is characterized in that it is formed in a wave shape by repeatedly projecting the protruding seal surface portion.

  According to a third aspect of the present invention, in the cylinder head structure of the internal combustion engine according to the second aspect, the head peripheral wall of the cylinder head having the sealing surface as an end surface is a head side wall opposite to the cam shaft support side. A wave shape in which the concave side wall and the convex side wall are repeated in accordance with the wave shape of the sealing surface is formed.

  According to a fourth aspect of the present invention, in the cylinder head structure of the internal combustion engine according to the third aspect, a head cover fastening bolt boss portion of a head cover fastening bolt for fastening the head cover to the cylinder head is sandwiched between the concave side walls of the head peripheral wall. The outer periphery of the valve cam chamber is protruded from the outer periphery.

According to the cylinder head structure of the internal combustion engine according to claim 1, the inner valve cam is combined with the head cover which is farthest from the combustion chamber and is deformed most greatly by expansion deformation of the cylinder head due to the combustion pressure in the combustion chamber. Since the seal surface that seals the chamber is on the side opposite to the camshaft support side, the fuel injection valve insertion boss portion and the head bolt boss portion are alternately connected to form an uneven shape in top view. A seal surface is formed from the central fuel injection valve insertion boss to the vicinity of the head bolt boss near the combustion chamber, effectively suppressing expansion and contraction of the cylinder head, eliminating many ribs. Thus, it is possible to realize a simple cylinder head structure with high rigidity while sufficiently reducing the weight.
In addition, the cam shaft support side of the cylinder head is formed with a cam bearing portion and has high rigidity.

  According to the cylinder head structure of the internal combustion engine according to claim 2, the head bolt boss portion is formed in series at intervals that sandwich each cylinder between the intake side outer edge portion and the exhaust side outer edge portion of the outer peripheral portion of the head. The seal surface on the side opposite to the shaft support side protrudes outwardly by curving the outer periphery along the recessed seal surface portion and the head bolt boss portion which are recessed to the valve operating cam chamber side at the fuel injection valve insertion boss portion. Since the convex seal surface portion is repeatedly formed into a wave shape, the connecting seal surface portion of the concave seal surface portion and the convex seal surface portion extends radially from the combustion chamber in a top view, and the cylinder head expands and The joint seal surface portion extending radially from the combustion chamber effectively acts against the contraction deformation, and the expansion / contraction deformation of the cylinder head can be suppressed.

According to the cylinder head structure of the internal combustion engine according to claim 3, the head peripheral wall of the cylinder head having the seal surface as an end surface is arranged such that the head side wall opposite to the cam shaft support side matches the wave shape of the seal surface. Since the concave side wall and the convex side wall form a wave shape that repeats, the connecting side wall portion of the concave side wall and the convex side wall extends radially from the combustion chamber in a top view, and further weight reduction is achieved with a small number of connecting side wall portions. However, the connecting side wall portion extending radially from the combustion chamber effectively acts on the expansion / contraction deformation of the cylinder head, and the expansion / contraction deformation of the cylinder head can be suppressed.
In addition, the degree of freedom of the layout of the recessed space formed outside the valve cam chamber sandwiched between the recessed side walls of the head peripheral wall can be improved.

  According to the cylinder head structure of the internal combustion engine according to claim 4, the head cover fastening bolt boss part is formed by protruding the outer periphery into the recessed space outside the valve cam chamber sandwiched between the recessed side walls of the head peripheral wall. Thus, the weight of the cylinder head can be reduced, and the head cover fastening bolt boss portion can be brought close to the cylinder axis line regardless of the outside of the valve operating cam chamber, thereby reducing the size of the cylinder head and the head cover.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
The internal combustion engine 1 of the present embodiment is a V-type 6-cylinder diesel engine.
Internal combustion engine 1 is mounted on a vertical vehicle arranged to direct the crankshaft 2 in the longitudinal direction of the vehicle, 3 the left bank inclined in the left and right by the cylinder B _L and the right bank B _R is configured in a V-(Figure 1 reference).

  Referring to FIG. 1, a crankcase 3 that stores a crankshaft 2 rotatably supported therein includes a left cylinder block 4L and a right cylinder block 4R in which three cylinders are arranged in series on the left and right, respectively, as viewed from the front. It is formed to extend obliquely upward so as to form a character.

The left and right cylinder heads 5L and 5R are diagonally superimposed on the left and right cylinder blocks 4L and 4R and fastened by the head bolts 8, and the left and right head covers 6L and 6R are respectively head cover fastening bolts on the left and right cylinder heads 5L and 5R. 9 is fastened and covered.
Note that an oil pan 7 covers the lower side of the crankcase 3.

Since the left bank _BL and the right bank _BR have a substantially bilaterally symmetric structure, the left and right cylinder heads 5L and 5R are also substantially bilaterally symmetric. I will explain.
Therefore, the left cylinder head 5L will be referred to as the cylinder head 5 and will be referred to as the left cylinder head 5L as necessary.

Referring to FIG. 1, a valve mechanism 50 provided in the cylinder head 5 (5L) is a SOHC type valve mechanism, and an intake valve 52 and an exhaust valve 53 are driven by a single cam shaft 51.
An intake side Si and an exhaust side Se are configured on opposite sides with respect to a plane including three central axis lines (cylinder axis lines) Lc of the three cylinder bores 4b of the left cylinder block 4L.
Bank inside between the left bank B _L and the right bank B _R is an outer intake side Si is an exhaust side Se.

  In the cylinder head 5, a pair of front and rear intake ports 11 opened to the combustion chamber 10 at the upper part of the cylinder bore 4b of each cylinder at the intake side Si extend toward the inside of the bank, and front and rear opened to the combustion chamber 10 at the exhaust side Se. A pair of exhaust ports 12 gathers together in the middle and extends toward the outside of the bank as a collective exhaust port 13.

  The intake valve 52 and the exhaust valve 53 are slidably supported by valve guides 52g and 53g fitted to the cylinder head 5, respectively, and the intake valve 52 opens and closes the opening of the intake port 11 facing the combustion chamber 10 to exhaust the exhaust. The valve 53 opens and closes an opening of the exhaust port 12 facing the combustion chamber 10.

One camshaft 51 that opens and closes the intake valve 52 and the exhaust valve 53 is disposed in the cylinder arrangement direction (front-rear direction) so as to be biased toward the exhaust side Se outside the bank of the cylinder head 5. Yes.
The cam shaft 51 is rotatably supported by being sandwiched between the cam bearing wall 28 and the cam holder 55 on the same surface as the mating surface of the cylinder head 5 (5L) with the left head cover 6L.

  An intake rocker arm 57 whose base end is pivotally supported by a rocker arm support shaft 56 is swingably disposed below the camshaft 51 near the intake side Si, and swells upward from the base end of the intake rocker arm 57. The intake cam of the cam shaft 51 is in contact with the protruding end, and the tip of the intake rocker arm 57 is in contact with the upper end of the valve stem of the intake valve 52.

  An exhaust rocker arm 58 is disposed below the cam shaft 51. The exhaust rocker arm 58 is spherically contacted with the head of the rocker arm fulcrum member 59 fitted to the cylinder head 5 at the base end, The exhaust cam of the camshaft 51 is in contact with the tip of the camshaft 51 and the tip of the camshaft 51 is in contact with the upper end of the valve stem of the exhaust valve 53.

  The rotation of the crankshaft 2 is transmitted through a cam chain transmission mechanism (not shown), and the camshaft 51 rotates at half the rotational speed of the crankshaft 2, and the camshaft 51 rotates through the intake rocker arm 57. Thus, the intake valve 52 is driven to open and close at a required timing, and the exhaust valve 53 is driven to open and close via the exhaust rocker arm 58 at a required timing.

An intake port 11 extending in the bank inside the curved orientation left and right banks B upward _L, is connected to an intake manifold 15 that is configured in common to B _R, merged exhaust port of the exhaust port 12 which extends to the bank outside 13 is directed obliquely downward and connected to the exhaust manifold 16.

The cylinder head 5 provided with the valve operating mechanism 50 is made of aluminum, and the structure thereof will be described below with reference to FIGS.
The cylinder head 5 has an outer shape in which a rectangular frame-shaped head peripheral wall 22 surrounds a rectangular head bottom wall 21 that is long in the front-rear direction, and the inside of the head peripheral wall 22 is provided at a substantially central height position. The upper space partitioned by the wall 23 is configured as a valve operating cam chamber 24 in which the valve operating mechanism 50 is disposed.

  The intake port 11, the exhaust port 12, and the collective exhaust port 13 are formed below the cam chamber bottom wall 23, and the upstream opening end surface 11a of the intake port 11 which is a mating surface connected to the intake manifold 15 is a head peripheral wall. The downstream opening end surface 13a of the collective exhaust port 13 which is a mating surface connected to the exhaust manifold 16 is formed at the lower portion of the left side wall 22l of the head peripheral wall 22 and is formed at an end portion that swells obliquely upward from the lower portion of the right side wall. Is formed.

  A cooling water passage space 25 is mainly formed in addition to the intake port 11, the exhaust port 12, and the collective exhaust port 13 above the head bottom wall 21 constituting the ceiling surface of the combustion chamber 10 and below the cam chamber bottom wall 23. Has been.

Further, a fuel injection valve insertion boss portion 26 for inserting the fuel injection valve 70 through the insertion hole along the cylinder axis Lc upward from the center of the ceiling surface of the combustion chamber 10 of the head bottom wall 21 Three cam chambers 24 are formed so as to protrude side by side in the cam shaft direction.
The internal combustion engine 1 is a direct injection internal combustion engine in which fuel is directly injected into the combustion chamber 10 by a fuel injection valve 70.

A pair of valve guides 52g of the intake valve 52 and valve guides 53g of the exhaust valve 53 are fitted to the intake side Si and the exhaust side Se, respectively, around each fuel injection valve insertion boss portion 26, and the outer periphery, that is, Four head bolt boss portions 27 having bolt holes 27 h through which the head bolt 8 passes are formed along the inner peripheral surface of the head peripheral wall 22 around the outer periphery of the combustion chamber 10.
The cylinder head 5 is fastened to the cylinder block 4L with four head bolts 8 around the outer periphery of the combustion chamber 10.

  Since the common head bolt boss portion 27 is formed between the adjacent combustion chambers 10, the head bolt boss portion 27 for each of the three combustion chambers 10 is provided on each of the intake side Si and the exhaust side Se on the outer periphery of the head. Four head bolt boss portions 27 are arranged in series on the outer edge portion at intervals that sandwich each cylinder in the cam shaft direction, and all the head bolt boss portions 27 are placed in the valve cam chamber 24 inside the head peripheral wall 22. is there.

The upper end surface of the head peripheral wall 22 forms a seal surface 22s that is sealed together with the head cover 6L and the seal member 18 to seal the inner valve cam chamber 24.
The upper end surface of the fuel injection valve insertion boss portion 26 is flush with the seal surface 22s, and the upper end surface of the head bolt boss portion 27 is in the valve cam chamber 24 and is lower than the seal surface 22s. The valve guides 52g and 53g protrude upward from the upper surface of the cam chamber bottom wall 23 at a lower position.

  The left side wall 22l on the exhaust side Se of the head peripheral wall 22 composed of the front, rear, left and right side walls above the cam chamber bottom wall 23 is straight along the four head bolt boss portions 27 arranged in series on the exhaust side Se. The cam bearing wall 28 is formed perpendicular to the cam shaft direction (front-rear direction) by connecting the left side wall 22l and the fuel injection valve fitting insertion boss portion 26 to each other.

The upper end surface of the cam bearing wall 28 forms a mating surface 28s, and a bearing arc surface 28a that supports the cam shaft 51 is formed so as to cut out the mating surface 28s into a semicircular arc shape. Bolt holes for fixing the cam holder 55 are formed in the mating surface 28s.
Bearing arc surfaces 22fa and 22ra and bolt holes 22fb and 22rb for supporting the camshaft 51 are also formed in the front side wall 22f and the rear side wall 22r of the head peripheral wall 22.

Therefore, the cam shaft 51 is supported by the bearing arc surface 28a of the cam bearing wall 28 and the bearing arc surfaces 22fa and 22ra of the front side wall 22f and the rear side wall 22r on the exhaust side Se from the cylinder axis Lc. It is sandwiched between the arc surface and the upper bearing arc surface of the front and rear side walls of the left head cover 6L and is held rotatably.
A head cover fastening bolt boss portion 29l having a female screw hole of a head cover fastening bolt 9 that bulges outward at least at the front and rear positions of the cam bearing wall 28 and fastens the left head cover 6L is formed from the left side wall 22l.

The right side wall of the intake side Si opposite to the exhaust side Se on which the cam shaft 51 is supported in the head peripheral wall 22 alternately has an outer peripheral portion in the vicinity of the head bolt boss portion 27 and a fuel injection valve insertion boss portion 26. They are connected to form an uneven shape when viewed from above.
That is, the right side wall of the head peripheral wall 22 is between the adjacent head bolt boss portions 27 and 27 and the convex side wall 22rp that is curved on the outer periphery along the head bolt boss portion 27 and protrudes to the outside of the valve operating cam chamber 24. The concave side walls 22rq that are recessed inside the valve operating cam chamber 24 toward the fuel injection valve insertion boss portion 26 are alternately formed to form a wave shape in which the convex side wall 22rp and the concave side wall 22rq are continuously repeated. is doing.

The head peripheral wall 22 is formed as described above, and therefore, the seal surface 22s, which is the end surface thereof, is linear along the four head bolt boss portions 27 of which the exhaust side Se is the exhaust side Se. Side Si is alternately connected to the outer peripheral portion in the vicinity of the head bolt boss portion 27 of the intake side Si and the fuel injection valve fitting boss portion 26 to form an uneven shape.
In other words, the intake side Si of the seal surface 22s corresponding to the right side wall of the head peripheral wall 22 has a protruding seal surface portion 22sp that protrudes outwardly by curving the outer periphery along the head bolt boss portion 27 and the fuel injection valve insertion. The boss portion 26 is formed into a wave shape by repeating the recessed seal surface portion 22sq that is recessed toward the valve operating cam chamber 24 side.

Therefore, as shown in FIG. 3, the joint seal surface portion 22sc of the concave seal surface portion 22sq on the end surface of the concave side wall 22rq and the convex seal surface portion 22sp on the end surface of the convex side wall 22rp in the head peripheral wall 22 is viewed from above. The fuel injection valve insertion boss 26 extends linearly from the combustion chamber 10 in the radial direction.
Corresponding to the intake-side seal surface 22s, the connecting side wall portion 22rc of the concave side wall 22rq and the convex side wall 22rp extends radially from the combustion chamber 10 on the right side wall.

A cam bearing wall 28 extends from the fuel injection valve insertion boss portion 26 to the exhaust side Se, and the end surface of the cam bearing wall 28 (the mating surface 28s with the cam holder 55) is flush with the seal surface 22s. It extends.
That is, in the cylinder head 5, a connecting side wall portion 22rc on one side and a cam bearing wall 28 on one side extend in a radial direction from a fuel injection valve fitting boss portion 26 located in the center of the combustion chamber 10. On the upper end surface of the head 5, a mating surface 28 s of two connecting seal surface portions 22 sc and one cam holder 55 extends from the fuel injection valve insertion boss portion 26 in the radial direction.

A cover fastening bolt 9 for fastening the head cover 6L is screwed into a recessed space 22v outside the valve cam chamber 24 sandwiched between two side walls 22rc of the intake side Si concave side wall 22rq of the head peripheral wall 22. A head cover fastening bolt boss portion 29r having a mating female screw hole 29rh is formed so that the outer periphery is thinned and protrudes upward.
The upper end surface of the head cover fastening bolt boss portion 29 r is at the same height as the seal surface 22 s of the head peripheral wall 22.

A clamp bolt hole 30 of a clamp mounting bolt 82, which will be described later, is formed at the deepest position facing the recessed space 22v outside the valve cam chamber 24 from which the head cover fastening bolt boss 29r protrudes.
The clamp bolt hole 30 is at a substantially intermediate position between the cover fastening bolt boss portion 29r and the fuel injection valve fitting insertion boss portion 26.

  Referring to FIG. 4 which is a perspective view showing a cross section taken along the line IV-IV passing through the fuel injection valve insertion boss portion 26 of FIG. 3, the fuel injection valve insertion boss portion 26 is fitted from the center of the combustion chamber 10. An insertion hole 26h penetrates upward, and a steel reinforcing cylindrical member 31 having a Young's modulus higher than aluminum is press-fitted into the upper maximum inner diameter portion of the fitting insertion hole 26h and protruded.

At the front-rear position (crank shaft direction position) where the fuel injection valve insertion boss portion 26 of the cylinder head 5 exists, the fuel injection valve insertion is performed on the exhaust side Se (right side in FIG. 4) from the fuel injection valve insertion boss portion 26. A cam bearing wall 28 orthogonal to the cam shaft 51 is connected between the insertion boss portion 26 and the left side wall 22l, and a reinforcing rib 32 is provided between the cam bearing wall 28 and the cam chamber bottom wall 23 below the cam bearing wall 28. They are connected (see FIGS. 4, 6 and 7).
An oil communication hole 24g communicating with the lower portion of the valve cam chamber 24 is opened near the fuel injection valve fitting boss portion 26 of the reinforcing rib 32.

Further, a high pressure oil passage 41 is bored in the cam shaft direction near the left side wall 22l of the reinforcing rib 32.
A bearing oil supply passage 42 is formed from the high pressure oil passage 41 so as to pass through the cam bearing wall 28 obliquely and open to the bearing arc surface 28a.

Referring to FIG. 4, the connecting wall 33 is connected between the cam chamber bottom wall 23 and the head bottom wall 21 at the same crankshaft direction position (front-rear position) as the fuel injection valve insertion boss portion 26. Is formed.
A part of the cooling water passage space 25 is opened to the connection wall 33 near the fuel injection valve insertion boss 26, and a collective exhaust port 13 is formed near the left side wall 22l.
A rectifying wall 34 is formed as an extension of the connecting wall 33 at a position in the same crankshaft direction as the fuel injection valve fitting insertion boss portion 26 around the pair of exhaust ports 12, 12 on the upstream side of the collective exhaust port 13.

  A stud female thread hole 36 for attaching the exhaust manifold 16 is formed in each of the cam chamber bottom wall 23 and the lower head bottom wall 21 above the collective exhaust port 13 in the downstream opening end face 13a of the collective exhaust port 13. Opened and drilled toward the right (left in FIG. 4).

On the other hand, on the intake side Si (leftward in FIG. 4) from the fuel injection valve insertion boss 26, a partition wall is formed so as to partition the coolant passage space 25 at the same crankshaft direction position as the fuel injection valve insertion boss 26. 35 is formed with a necessary minimum opening for communicating with the coolant passage space 25.
The partition wall 35 is provided with the clamp bolt hole 30 and a plug hole 37 into which a shield plug (preheating plug) 71 is inserted obliquely upward to the left from the combustion chamber 10.

  As described above, the cylinder head 5 includes the partition wall 35 on the intake side Si and the cam bearing wall 28 and the reinforcing rib on the exhaust side Se at the front and rear positions where the fuel injection valve insertion boss portion 26 exists. 32, the connecting wall 33, and the rectifying wall 34 are connected to the cam chamber bottom wall 23 and the head bottom wall 21 to form a series of continuous walls excluding the minimum required cooling water passage space 25 and the like.

The lubrication system of the cylinder head 5 will be briefly described. The high-pressure oil passage 41 drilled in parallel with the camshaft 51 diagonally below the camshaft 51 is a high-pressure that supplies oil to the lubrication part of the valve mechanism 50. The bearing oil supply passage 42 for supplying oil to the bearing portion of the camshaft 51 is branched from the middle, and the intake rocker arm oil supply passage 43i for supplying oil to the sliding portion of the intake rocker arm 57 is branched toward the intake side Si. An exhaust rocker arm oil supply passage 43e for supplying oil to the sliding portion of the exhaust rocker arm 58 branches in the vertical direction along the high pressure oil passage 41 (see FIGS. 3 and 6).
The rocker arm fulcrum member 59 is fitted into the exhaust rocker arm oil supply passage 43e, and oil is supplied to the spherical contact portion with the exhaust rocker arm 58 via the rocker arm fulcrum member 59.

Referring to FIGS. 5 and 6, the large-diameter opening 45 protrudes from the left side wall 22 l of the cylinder head 5 through the small-diameter opening 44 on the opposite side (exhaust side Se) of the high-pressure oil passage 41 to the intake rocker arm oil supply passage 43 i. Is formed.
That is, a small-diameter opening 44 is formed in communication with the high-pressure oil passage 41 on the back side of the large-diameter opening 45 that opens on the side surface of the left side wall 22 l of the cylinder head 5.

A seal ball 72, which is a first seal member, is press-fitted into the small-diameter opening portion 44 to block and close the high-pressure oil passage 41 from the large-diameter opening portion 45. The large-diameter opening portion 45 has a seal cap 73 as a second seal member. Is inserted to block and close the inside of the large-diameter opening 45 from the outside.
The second seal member may be any member as long as it can be prevented from falling off, such as a seal cap, and may be screwed and fixed, for example, like a seal plug.

As shown in FIGS. 5 and 6, a cavity 45c is formed inside the seal cap 73 fitted with the large-diameter opening 45 between the seal ball 72 and a low-pressure oil passage in the cavity 45c. An opening 47a of the oil return passage 47 is formed obliquely below and below.
The opening 47 a of the oil return passage 47 has an inner diameter larger than the inner diameter of the small-diameter opening 44.
An oil return port 46 penetrating the cam chamber bottom wall 23 is formed above the opening 47 a of the oil return passage 47.

Right cylinder head 5R of the right bank B _R of the same structure as the left bank B _L in Fig. 1, right cylinder block 4R, with reference to the crankcase 3, the sealing ball 72 in the large diameter opening 45 of the right cylinder head 5R and the seal The oil return passage 47 opened in the cavity 45c between the caps 73 extends downward along the side wall surface on the exhaust side parallel to the cylinder axis Lc, and communicates with the oil return passage 48 of the right cylinder block 4R and the crankcase 3. The oil is returned to the oil pan 7 from the oil return passage 48.

Therefore, the oil that has lubricated the lubrication part of the valve mechanism 50 in the valve cam chamber 24 gathers on the cam chamber bottom wall 23 and flows to the exhaust side Se through the cam chamber bottom wall 23 whose exhaust side Se is inclined low. The oil flows into the return port 46, flows down the oil return passages 47 and 48, and is stored in the oil pan 7.
Also, if the high pressure oil passage 41 has an unnecessarily high pressure for some reason and the seal ball 72 may fall off from the small diameter opening 44, the oil leaking from the small diameter opening 44 The oil flows into the oil return passage 47 from the cavity 45 c and is returned to the oil pan 7.

Even if the seal ball 72 falls off from the small-diameter opening 44, the high pressure does not act on the seal cap 73, the blockage by the seal cap 73 is ensured, and the oil is surely prevented from leaking to the outside.
Note that the seal ball 72 dropped from the small-diameter opening 44 is also guided from the cavity 45c to the opening 47a having a larger inner diameter than the small-diameter opening 44 formed on the lower side, falls, passes through the oil return passages 47 and 48, and passes through the oil pan 7 Therefore, it can be easily collected.

  The cylinder head 5 (5L) generally as described above is superimposed on the left cylinder block 4L integrated with the crankcase 3, and the head bolt 8 penetrating the bolt hole 27h of the head bolt boss portion 27 on the outer periphery of the combustion chamber 10 is formed. The cylinder head 5 (5L) is fastened to the left cylinder block 4L by being screwed into the left cylinder block 4L.

  Since the upper end surface of the head bolt boss portion 27 is at a position lower than the sealing surface 22sp of the curved convex side wall 22rp and is in the valve operating cam chamber 24, the upper surface of the head bolt boss portion 27 is above the head bolt boss portion 27 to which the head bolt 8 is fastened. The end face is completely cut off from the outside air, and the durability of fastening by the head bolt 8 can be improved even if the cylinder head 5 is expanded or contracted.

The left head cover 6L placed on the cylinder head 5 (5L) has a structure as shown in FIG.
The left head cover 6 </ b> L has a cover upper wall 61 formed by bulging upward the inside of a longitudinal rectangular cover frame portion 62 having a seal surface 6 s facing the seal surface 22 s of the cylinder head 5.

The exhaust side Se of the cover frame portion 62 is formed with a straight left side wall 62l similar to the left side wall 22l of the cylinder head 5, and a bolt boss portion 63l corresponding to the cover fastening bolt boss portion 29l from the straight left side wall 62l. Bulges.
On the other hand, on the intake side Si of the cover frame portion 62, the large convex wall 62p corresponding to the convex side wall 22rp of the cylinder head 5 and the small convex wall 62q bulging small so as to cover the cover fastening bolt boss portion 29r are alternately continued. An uneven shape is formed.

A bolt boss portion 63r is formed along the small convex wall 62q corresponding to the cover fastening bolt boss portion 29r of the cylinder head 5.
A fuel injection valve through boss portion 64 is formed on the cover upper wall 61 corresponding to the fuel injection valve insertion boss portion 26 of the cylinder head 5 with a fuel injection valve through hole 64h. An open cavity 65 is formed between the insertion boss 26 and the bolt boss 63r.
A small opening cavity 66 is also formed in front of the vicinity of the bolt boss 63r.

  These open cavities 65 and 66 correspond to the recessed space 22v outside the valve cam chamber 24 sandwiched between the concave side walls 22rq of the cylinder head 5. In particular, the open cavities 65 are connected to the clamp bolt holes 30. It is formed at the overlapping position.

  FIG. 10 shows an exploded perspective view of the left cylinder head 5L and a part of the periphery thereof with a part of the valve mechanism 50 omitted, and FIG. 11 shows a perspective view of the assembled state.

On the exhaust side Se of the cylinder head 5 (5L), a stud bolt 76 is screwed and protruded into a stud female screw hole 36 formed in the downstream opening end surface 13a of the collective exhaust port 13, and this downstream opening end surface 13a. The mounting board 16f of the exhaust manifold 16 is brought into contact with the stud bolt 76 that protrudes at that time, and is passed through the mounting hole 16fb of the mounting board 16f.
Then, a nut 77 is screwed and tightened to a stud bolt 76 penetrating the mounting hole 16fb of the mounting substrate 16f, and the exhaust manifold 16 is attached to the cylinder head 5 to connect the collective exhaust port 13 to the exhaust pipe of the exhaust manifold 16.

  On the other hand, on the upper side of the cylinder head 5 (5L), the lower half portion of the steel reinforcing cylindrical member 31 is press-fitted into the upper portion of the insertion hole 26h of the fuel injection valve insertion boss portion 26 so that the upper half portion protrudes. The camshaft 51 is mounted on the bearing arc surface 28a of the cam bearing wall 28 on the exhaust side Se from the reinforcing cylindrical member 31, and the cam holder 55 is fixed to the cam bearing wall 28 by the bolt 75. The cam shaft 51 is sandwiched and held rotatably.

  The seal member 18 is attached to the seal surface 6s of the head cover 6L, and the three fuel injection valves of the head cover 6L are attached to the three reinforcing cylindrical members 31 protruding from the fuel injection valve insertion boss portion 26 of the cylinder head 5. The head cover 6L is overlaid on the cylinder head 5 via the seal member 18 so as to fit the through hole 64h, and the cover fastening bolt 9 is passed through the bolt boss portions 63l and 63r on the periphery of the head cover 6L. Are fastened by screwing into the female screw holes 29lh and 29rh of the cover fastening bolt boss portions 29l and 29r.

Next, the fuel injection valve 70 is passed through the fuel injection valve through hole 64h of the head cover 6L and is inserted into the insertion hole 26h of the fuel injection valve insertion boss portion 26 of the cylinder head 5.
At that time, the clamp mechanism 80 of the fuel injection valve 70 is also assembled together.

In the fuel injection valve 70, a small-diameter nozzle portion 70b projects from the tip of a large-diameter nozzle body portion 70a, and a flange 70c projects from a predetermined location on the base end side of the nozzle body portion 70a.
On the other hand, a small diameter portion 26hb into which the nozzle portion 70b of the fuel injection valve 70 is inserted is formed in the insertion hole 26h of the fuel injection valve insertion boss portion 26 of the cylinder head 5, and the step is started from the small diameter portion 26hb. A large diameter portion 26ha is formed via the portion 26hd (see FIG. 4).

Therefore, the fuel injection valve 70 inserted into the insertion hole 26h of the fuel injection valve insertion boss 26 inserts the nozzle portion 70b into the small diameter portion 26hb and contacts the tip end surface of the nozzle body portion 70a with the step portion 26hd. By contacting, the fuel injection valve 70 is positioned in the axial direction.
The fuel injection valve 70 thus positioned in the axial direction has the nozzle body portion 70a held by the steel reinforcing cylindrical member 31, and passes through the fuel injection valve through hole 64h of the head cover 6L so that the upper portion protrudes to the outside. ing.

  A clamp member 81 that holds the fuel injection valve 70 on the proximal end side of the nozzle body portion 70a is formed with a through hole 81h through which a clamp mounting bolt 82 passes at a substantially central portion with reference to FIGS. A pressing fork portion 81a and a support arm portion 81b extend in directions opposite to each other across the central portion where the through hole 81h is formed.

The presser fork portion 81a extends in a fork-like manner from the center portion, and is engaged so as to sandwich the upper side of the flange 70c on the base end side (upper portion) of the nozzle body portion 70a of the fuel injection valve 70, An axial load is equally applied to the flange 70c from both sides of the center portion.
On the other hand, the tip of the support arm 81b comes into contact with the head of the head cover tightening bolt 9 on the intake side Si from above.

  The clamp mounting bolt 82 that passes through the through hole 81h in the center of the clamp member 81 has a head 82a that extends through the through hole 81h from above and has an enlarged diameter at the upper end in contact with the upper end surface of the through hole 81h. 5 is inserted into the clamp bolt hole 30 and is screwed by the lower screw portion 82b.

When the fuel injection valve 70 is inserted into the insertion hole 26h of the fuel injection valve insertion boss portion 26 of the cylinder head 5, the clamp mechanism 80 is assembled together.
That is, referring to FIG. 10, the presser fork portion 81 a of the clamp member 81 is engaged with the upper portion of the nozzle body portion 70 a of the fuel injection valve 70 directly above the flange 70 c and is inserted into the through hole 81 h in the center portion of the clamp member 81. With the clamp mounting bolt 82 penetrated, the fuel injection valve 70 is passed through the fuel injection valve through hole 64h of the left head cover 6L from above the head cover 6L, and the fuel injection valve insertion boss portion 26 of the cylinder head 5 is inserted. Simultaneously with the insertion into the hole 26h, the clamp mounting bolt 82 is passed through the opening cavity 65 formed in the left head cover 6L and screwed into the clamp bolt hole 30 of the cylinder head 5.

  Then, in the clamp member 81, the presser fork 81a presses the flange 70c of the nozzle body 70a of the fuel injection valve 70 downward in the axial direction, and the tip of the support arm 81b is the head of the head cover tightening bolt 9 of the intake side Si. It abuts on the part from above.

  When the clamp mounting bolt 82 is screwed into the clamp bolt hole 30 to a predetermined depth and fixed to the highly rigid cylinder head 5, the clamp member 81 is fixed at the center by the clamp mounting bolt 82, and the support arm portion 81b The tip end portion is also supported in contact with the head cover fastening bolt 9 fastened to the cylinder head 5, and the fuel injection valve 70 is pressed and fixed so that the presser fork portion 81a on the opposite side presses the flange 70c. The rigidity is high and the fuel injection valve 70 can be firmly fixed (see FIGS. 11 and 12).

  Further, when the fuel injection valve 70 is removed for maintenance or the like, the fuel injection valve 70 can be removed together with the clamp mechanism 80 by loosening the clamp mounting bolt 82 while keeping the head cover 6L fastened to the cylinder head 5.

  In the internal combustion engine 1 as a diesel engine as described above, the large combustion pressure in the combustion chamber 10 at the upper part of the cylinder is expanded in the radial direction around the portion constituting the top surface of the combustion chamber 10 of the cylinder head 5, and the combustion pressure is increased. Therefore, the seal surface that is combined with the head cover 6L farthest from the combustion chamber 10 and seals the inner valve cam chamber 24 tends to expand and contract most greatly.

  Therefore, in the cylinder head 5, the suction surface Si of the intake side Si opposite to the exhaust side Se on which the camshaft 51 is supported has a concavo-convex shape, that is, a concave seal surface portion 22sq and a convex seal surface portion 22sp. Since the connecting seal surface portion 22sc of the concave seal surface portion 22sq and the convex seal surface portion 22sp extends linearly from the combustion chamber 10 in the radial direction, the cylinder head expands and contracts. Deformation can be effectively suppressed, and a simple cylinder head structure with high rigidity can be realized while sufficiently reducing weight by omitting many ribs.

  Note that the cam shaft support side (exhaust side Se) of the cylinder head 5 has a radial direction in which the mating surface 28a, which is the end surface of the cam bearing portion wall 28, is flush with the connecting seal surface portion 22sc together with the cam bearing portion wall 28. The cylinder head has high rigidity and can effectively suppress expansion / contraction deformation of the cylinder head.

The head peripheral wall 22 of the cylinder head 5 having the seal surface 22s as an end surface has a head side wall opposite to the cam shaft support side (intake side Si), a concave side wall 22rq and a convex side wall according to the wave shape of the seal surface 22s. Since the wave shape is repeated 22rp, the connecting side wall portion 22rc of the concave side wall 22rq and the convex side wall 22rp extends radially from the combustion chamber in the top view, and the weight is reduced by the small connecting side wall portion 22rc. Further, the connecting side wall portion 22rc extending radially from the combustion chamber 10 effectively acts on the expansion / contraction deformation of the cylinder head 5 to suppress the expansion / contraction deformation of the cylinder head 5.
Further, it is possible to improve the degree of freedom of the layout of the recessed space 22v formed outside the valve cam chamber 24 sandwiched between the two connected side wall portions 22rc of the concave side wall 22rq of the head peripheral wall 22.

  Since the head cover fastening bolt boss portion 29r is formed by protruding the outer periphery of the recessed space 22v so as to reduce the weight of the cylinder head 5, the head cover fastening bolt boss portion 29r is placed outside the valve cam chamber 24. Regardless, the cylinder head 5 and the head cover 6L can be downsized close to the cylinder axis Lc.

1 is a cross-sectional view of an internal combustion engine according to an embodiment of the present invention. It is a perspective view of a cylinder head. It is a top view of the cylinder head. It is the perspective view of the cylinder head cut | disconnected by the IV-IV line | wire of FIG. FIG. 5 is a perspective view of the cylinder head cut along line VV in FIG. 3. It is sectional drawing of the cylinder head cut | disconnected by the VI-VI line of FIG. It is sectional drawing of the cylinder head cut | disconnected by the VII-VII line of FIG. It is sectional drawing of the cylinder head cut | disconnected by the VIII-VIII line of FIG. It is a top view of a head cover. It is the disassembled perspective view which abbreviate | omitted one part and cut | disconnects the left cylinder head and its periphery partially. FIG. 3 is a partially cut perspective view of the left cylinder head and its surrounding assembled state. FIG.

Explanation of symbols

Si ... intake side, Se ... exhaust side, 1 ... internal combustion engine, 2 ... crankshaft, 3 ... crankcase, 4L ... left cylinder block, 4R ... right cylinder block, 5 (5L) ... left cylinder head, 5R ... right cylinder Head, 6L ... Left head cover, 6R ... Right head cover, 8 ... Head bolt, 9 ... Head cover fastening bolt, 10 ... Combustion chamber,
21 ... Head bottom wall, 22 ... Head peripheral wall, 22s ... Seal surface, 22sp ... Convex seal surface portion, 22sq ... Concave seal surface portion, 22sc ... Concatenation seal surface portion, 22rp ... Convex side wall, 22rq ... Concave side wall, 22rc ... Concatenation Side wall portion, 23 ... bottom wall of cam chamber, 24 ... valve operating cam chamber, 26 ... fuel injection valve insertion boss, 27 ... head bolt boss, 28 ... cam bearing wall, 29l, 29r ... head cover fastening bolt boss, 31 ... reinforcing cylindrical member, 70 ... fuel injection valve.

Claims (4)

A plurality of cylinders are arranged in series, an intake side and an exhaust side are configured on opposite sides with respect to a plane including the cylinder axis of each cylinder, and an intake side intake valve and an exhaust side exhaust valve drive camshaft are connected to the intake side. In a cylinder head structure of an internal combustion engine provided with a fuel injection valve that is arranged in the direction of cylinder arrangement and is biased toward either one of the exhaust side, and that directly injects fuel into the combustion chamber at the top of each cylinder.
A fuel injection valve insertion boss portion for inserting the fuel injection valve is formed by penetrating the insertion hole upward from a substantially central position of each combustion chamber of the cylinder head,
A plurality of head bolt boss portions through which a head bolt for fastening the cylinder head to the cylinder block passes are formed on the outer periphery of the head of the cylinder head,
A seal surface which is combined with the head cover of the cylinder head and seals the inner valve cam chamber accommodates the head bolt boss portion on the inner side, and the cam shaft support side on which the cam shaft is supported on the intake side and the exhaust side A cylinder head structure for an internal combustion engine, wherein the fuel injection valve insertion boss part and the vicinity of the head bolt boss part are alternately connected to each other on the opposite side to form an uneven shape in a top view. The head bolt boss portion is formed in series at intervals that sandwich each cylinder between the intake side outer edge portion and the exhaust side outer edge portion of the outer periphery of the head,
A seal surface on the camshaft support side where the camshaft is supported on the intake side and the exhaust side is formed linearly along the head bolt boss portion formed in series,
The seal surface opposite to the camshaft support side is curved at the outer periphery along the recessed seal surface portion that is recessed toward the valve operating cam chamber by the fuel injection valve insertion boss portion, and the head bolt boss portion. 2. The cylinder head structure for an internal combustion engine according to claim 1, wherein the protruding seal surface portion protruding outward is formed into a wave shape.   The head peripheral wall of the cylinder head having the sealing surface as an end surface forms a wave shape in which the head side wall opposite to the cam shaft support side has a wave shape in which the concave and convex side walls are repeated in accordance with the wave shape of the sealing surface. 3. A cylinder head structure for an internal combustion engine according to claim 2, wherein:   A head cover fastening bolt boss portion of a head cover fastening bolt for fastening the head cover to the cylinder head is formed by protruding the outer periphery into a recessed space outside the valve cam chamber sandwiched between the concave side walls of the head peripheral wall. The cylinder head structure for an internal combustion engine according to claim 3, wherein

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