JP3027896B2 - Cylinder head of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a cylinder head of an internal combustion engine.

[0002]

2. Description of the Related Art In general, an internal combustion engine having an intake camshaft and an exhaust camshaft on a cylinder head is provided with a chain and a sprocket for transmitting the rotational force of the crankshaft to both camshafts. A chain tensioner device for applying tension is provided.

[0003] As a conventional chain tensioner device, for example, there is one shown in FIGS. 6 and 7 (Japanese Utility Model Publication No. 47-1623).
Publication No.).

[0004] To explain this, the sprocket 5
Chain 60 looped between the sprocket 8 and the sprocket 59
The shoe 61 slidingly in contact with the sleeve 62 is connected to the sleeve 62, the cylindrical sleeve 62 is slidably fitted to the body 63, and a spring 64 is interposed between the sleeve 62 and the body 63. , A hydraulic chamber 65 is defined.

[0005] The sleeve 62 is pushed up by the hydraulic pressure guided to the hydraulic chamber 65 and the urging force of the spring 64, and the shoe 61 is pressed against the chain 60 to apply a predetermined tension to the chain 60.

The shoe 61 is rotatably supported around the axis of the sleeve 62. The shoe 61 slightly rotates following a slight orbital change of the chain 60, thereby smoothly guiding the circulation of the chain 60. I have.

[0007]

The shoe 61
May be largely displaced relative to the path of the chain 60, and when the angle of the shoe 61 is greatly shaken, the chain 60 may fall off.

As described above, the guide plate 66 is provided on the body 63 at one side of the shoe 61 in order to prevent the shoe 61 from being largely displaced relative to the path of the chain 60. Are in contact with each other when they swing by a predetermined angle, preventing further rotation. However, the mounting of the guide plate 66 causes the structure to be complicated, and also increases the size of the apparatus.

An object of the present invention is to provide a mounting structure of a chain tensioner device suitable for an internal combustion engine having an intake camshaft and an exhaust camshaft on a cylinder head, focusing on the above problems.

[0010]

SUMMARY OF THE INVENTION The present invention comprises an intake camshaft for opening and closing an intake valve and an exhaust camshaft for opening and closing an exhaust valve on a cylinder head, between cam sprockets connected to the respective camshafts. A front end journal portion for supporting an intake camshaft, and a front end for supporting an exhaust camshaft, in a cylinder head of an internal combustion engine having a chain that is hung around the chain and a chain tensioner device that presses a shoe that slides on the chain against the chain. A journal portion, a journal connecting beam portion connecting both front end journal portions, a column portion connecting the journal connecting beam portion and a lower wall portion of the valve operating chamber, and a mounting seat connected to the journal connecting beam portion to support the chain tensioner device. And a guide rib that is connected to the column and faces the side of the shoe and regulates rotation of the shoe. .

[0011]

The shoe guides the circulation of the chain smoothly by slightly rotating following the fluctuation of the trajectory of the chain. Since the cylinder head has guide ribs facing the side of the shoe, when the shoe is relatively displaced relative to the chain, the side of the shoe hits the guide rib and the movement of the shoe to rotate more than that is locked. , The shoe is kept in a rotational position along the circulation path of the chain. By forming the guide rib on the cylinder head, the guide plate and the like provided in the conventional device can be eliminated, and the structure can be simplified and the size can be reduced.

The cylinder head has a journal connecting beam connecting the front end journals on the intake side and the exhaust side, and a column connecting the journal connecting beam and the lower wall of the valve operating chamber. While increasing the rigidity of
The support rigidity of each camshaft can be sufficiently ensured.

Since the cylinder head has a mounting seat for the chain tensioner device in the journal connecting beam portion, sufficient rigidity for supporting the chain tensioner device can be ensured.

Since a gap is formed around the column to communicate the valve operating chamber and the chain chamber, lubricating oil collected at the bottom of the valve operating chamber after lubricating the camshaft and the like is prevented from flowing around the column. It flows down from the gap through the chain chamber to an oil pan (not shown) to lubricate the crank sprocket and the chain wound around it.

[0015]

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

As shown in FIG. 1, an intake camshaft 2 for opening and closing an intake valve and an exhaust camshaft 3 for opening and closing an exhaust valve are provided on a cylinder head 1 of an internal combustion engine. Intake cam sprocket 4
And a chain tensioner device 8 for pressing a shoe 7 against the chain 6.

A separate sprocket (not shown) is connected to one of the camshafts 2 and 3, and the rotational force from the crankshaft is transmitted through a chain wound around the sprocket.

In FIG. 2, reference numerals 11 and 12 denote journal portions for supporting the intake camshaft 2, reference numerals 13 and 14 denote journal portions for supporting the exhaust camshaft 3, reference numeral 15 denotes a valve guide hole through which an intake valve is inserted, and reference numeral 16 denotes an exhaust valve. , A spark plug boss through which a spark plug is inserted,
Reference numeral 18 denotes a head bolt boss through which a head bolt for fastening the cylinder head 1 to the cylinder block is inserted.

As shown in FIG. 3, a front end journal portion 11 for supporting the intake camshaft 2 on the cylinder head 1 is provided.
And the front end journal portion 1 supporting the exhaust camshaft 3
3 are integrally formed.

The other ends of the front end journals 11 and 13 are connected to left and right side walls 22 and 23 of the cylinder head 1.

A first column 25 connecting the journal connecting beam 21 and the lower wall 24 of the valve operating chamber 28 of the cylinder head 1 is integrally formed. The first pillar portion 25 is formed so as to be orthogonal to the journal connecting beam portion 21 and offset so as to be close to the front end journal portion 11 on the intake side.

The front end journal portion 13 on the exhaust side and the valve train chamber 2
A second pillar portion 26 that connects the lower wall portions 24 at an angle is integrally formed.

The front end journal section 11 on the intake side and the valve train chamber 2
A third pillar 27 that connects the lower wall portions 8 of the plurality 8 is integrally formed.

Between the three pillars 25, 26, 27, there is formed a gap 30 communicating the valve operating chamber 28 located at the rear thereof and the chain chamber 29 located at the front thereof.

As shown in FIG. 4, a mounting seat 31 for the chain tensioner device 8 is integrally formed on the upper surface of the journal connecting beam portion 21. The body 32 of the chain tensioner device 8 is fastened to the journal connecting beam 21 via two bolts 33. For this reason, a screw hole 34 for screwing each bolt 33 is formed in the journal connecting beam 21.

A concave portion 39 is formed on the front surface of the journal connecting beam portion 21 to engage with the body 32 of the chain tensioner device 8.

As shown in FIG. 5, the chain tensioner device 8 includes a shoe 7 having a sliding surface 41 which is in sliding contact with the chain 6, and a cylindrical sleeve for pressing the shoe 7 against the chain 6. 42.

The sleeve 42 is slidably fitted to the body 32 and rotatably supports the shoe 7 around the axis of the sleeve 42.

A spring 43 is interposed between the sleeve 42 and the body 32, and a hydraulic chamber 4 is interposed therebetween.
5, the sleeve 42 is pushed down by the hydraulic pressure guided to the hydraulic chamber 45 and the urging force of the spring 43, and the shoe 7 is pressed against the chain 6 to apply a predetermined tension to the chain 6.

The body 32 has a substantially L-shaped cross section, and accommodates a reservoir tank 47 for storing lubricating oil fed from an engine oil pump through an oil passage 55 formed in the cylinder head 1 and the sleeve 42. Cylinder portions 48 are provided orthogonal to each other. The lower surface 49 of the reservoir tank 47 is joined to the mounting seat 31 of the cylinder head 1.

In the upper part of the reservoir tank 47, an air vent hole 50 communicating with the chain chamber 29 is formed. The air contained in the lubricating oil stored in the reservoir tank 47 is released to the chain chamber 29 through the air vent hole 50, and the lubricating oil from which the air has been removed is passed through the check valve 46 to the hydraulic chamber 4.
5 and is replenished with the lubricating oil that has leaked from the gap around the sleeve 42.

A first guide rib 52 is formed integrally with the cylinder head 1 so as to be connected to the first column 25. The first guide rib 52 opposes the side portion 51 of the shoe 7 with a predetermined gap and regulates the rotation of the shoe 7.

The second guide rib 53 is suspended from the journal connecting beam 21 on the cylinder head 1.
Are integrally formed. The second guide rib 53 opposes the side portion 51 of the shoe 7 with a predetermined gap and regulates the rotation of the shoe 7.

The first guide rib 52 and the second guide rib 53
Are arranged in parallel at a predetermined interval from each other so as to face both ends of the shoe 7.

Next, the operation will be described.

The shoe 7 is rotatably supported around the axis of the sleeve 42. The shoe 7 slightly rotates following a slight orbital change of the chain 6 to smoothly guide the circulation of the chain 6. I have.

Since the first guide rib 52 and the second guide rib 53 face each other with a predetermined gap on the side portion 51 of the shoe 7, when the shoe 7 is relatively displaced relative to the chain 6, the side of the shoe 7 The portion 51 is the first guide rib 5
By contacting the second or second guide rib 53, the movement of the shoe 7 to rotate more than that is locked, and the shoe 7 is kept at the rotational position along the circulation path of the chain 6.

By forming the first guide rib 52 and the second guide rib 53 integrally with the cylinder head 1,
The guide plate and the like provided in the conventional device can be eliminated, and the structure can be simplified and downsized.

The cylinder head 1 has a front end journal 1
Combustion pressure and thermal stress are formed by integrally forming one journal connecting beam portion 21 connecting 1 and 13 and three column portions 25 connecting the journal connecting beam portion 21 and the lower wall portion 24 of the valve operating chamber 28. And the supporting rigidity of each of the camshafts 2 and 3 can be sufficiently ensured.

Further, since the cylinder head 1 has the mounting seat 31 for the chain tensioner device 8 formed in the journal connecting beam portion 21, the support rigidity of the chain tensioner device 8 can be sufficiently ensured.

Between each of the three pillars 25, 26, 27, there is formed a gap 30 communicating the valve chamber 28 located at the rear thereof with the chain chamber 29 located at the front thereof. After lubricating the camshafts 2, 3 etc., the valve train chamber 2
The lubricating oil collected at the bottom of the cylinder sprocket 8 flows down from the gaps 30 between the columns 25, 26, and 27 through the chain chamber 29 to an oil pan (not shown). Lubricate the chain and the like that are hung around.

[0042]

As described above, the present invention comprises an intake camshaft for driving the opening and closing of an intake valve and an exhaust camshaft for driving the opening and closing of an exhaust valve on a cylinder head, and a cam sprocket connected to each camshaft. In a cylinder head of an internal combustion engine having a chain tensioned between the chain and a chain tensioner device for pressing a shoe that slides on the chain against the chain, a front end journal portion that supports an intake camshaft and an exhaust camshaft are supported. A front end journal portion, a journal connecting beam portion connecting both front end journal portions, a column portion connecting the journal connecting beam portion and a lower wall portion of the valve operating chamber, and an attachment connecting the journal connecting beam portion to support the chain tensioner device. And a guide rib connected to the column and facing the side of the shoe to regulate the rotation of the shoe. Therefore, it is possible to eliminate a large guide plate or the like that locks the rotation of the shoe provided in the conventional device, thereby simplifying the structure of the chain tensioner device and ensuring sufficient support rigidity of the device. You.

[Brief description of the drawings]

FIG. 1 is a front view of a cylinder head showing an embodiment of the present invention.

FIG. 2 is a plan view of the cylinder head.

FIG. 3 is a sectional view taken along the line KK of FIG. 2;

FIG. 4 is a perspective view of the same cylinder head and chain tensioner device.

FIG. 5 is a sectional view of the chain tensioner device.

FIG. 6 is a side view of a chain tensioner device showing a conventional example.

FIG. 7 is a sectional view of the chain tensioner device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Intake camshaft 3 Exhaust camshaft 4 Intake cam sprocket 5 Exhaust cam sprocket 6 Chain 7 Shoe 8 Chain tensioner device 11 Front end journal part 13 Front end journal part 21 Journal connection beam part 24 Valve train chamber lower wall part 25 First Column 30 Gap 31 Mounting seat 51 Shoe side 52 First guide rib 53 Second guide rib

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-203345 (JP, A) JP-A-4-86357 (JP, A) JP-A 8-49508 (JP, A) JP-A-3-203 79842 (JP, A) JP-A-7-145711 (JP, A) JP-A-6-26312 (JP, A) JP-A-5-214905 (JP, A) JP-A-2-69001 (JP, U) 47-162 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02F 1/24 F01L 1/04 F02B 67/06 F16H 7/08

Claims (1)

(57) [Claims] An intake camshaft for opening and closing an intake valve and an exhaust camshaft for opening and closing an exhaust valve on a cylinder head; and a chain hung between cam sprockets connected to the respective camshafts. In an internal combustion engine provided with a chain tensioner device for pressing a shoe that slides on a chain against a chain, a front end journal supporting an intake camshaft, a front end journal supporting an exhaust camshaft, and a journal connecting both front end journals. A connecting beam, a column connecting the journal connecting beam and the lower wall of the valve operating chamber, a mounting seat connected to the journal connecting beam to support the chain tensioner device, and a shoe side connected to the column. And a guide rib for restricting rotation of the shoe facing the portion. .