JPH06317110A - Structure of cylinder head - Google Patents

Abstract

PURPOSE:To facilitate attaching of rocker shafts on a cylinder head of an engine having a valve system in which the rocker shafts oscillate together with rocker arms. CONSTITUTION:A rocker shaft cap 34 loaded on a cylinder head of an engine provided with a valve system in which rocker shafts oscillate together with rocker arms, and supporting the rocker shafts, is formed into a ladder frame structure by forming plural cap parts 34a supporting the respective rocker shafts integrally with beam parts 34b, 34b' supporting both sides of each of the cap parts, and in its structure, oil passages are provided in the respective beam parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cylinder head.

[0002]

2. Description of the Related Art As a valve mechanism, in order to improve the output torque of the engine in the high speed range while maintaining the ease of use in the low speed range of the engine, that is, while maintaining the low speed and high torque.
Two types of cams with different profiles, for low speed and high speed, are set on the camshaft, and hydraulic pressure is used to drive the valve with the low speed cam in the low speed rotation range of the engine and the high speed cam in the high speed rotation range. There is a variable valve timing mechanism that can be switched. Various variable valve timing mechanisms have been proposed, and the applicant has proposed variable valve timing mechanisms as shown in FIGS. 12 and 13.

A variable valve timing mechanism 1 shown in FIGS. 12 and 13 has two valves 2 and 3 and a T-type rocker arm 5 integrated with rocker shafts 4 and 4'for opening and closing these valves 2 and 3. A low-speed rocker arm 6, a high-speed rocker arm 7, and a T-type rocker arm 5, and pistons 8 and 9 and a cam for selectively connecting the low-speed rocker arm 6 or the high-speed rocker arm 7 to the T-type rocker arm 5. Low speed cam 14 provided on the shaft 13,
It is composed of a high-speed cam 15 and the like.

Rocker shafts 4 and 4'at both ends of the T-shaped rocker arm 5 are rotatably supported by rocker shaft journals 12 and 12 ', and an oil passage 4 provided in the journal 12' and rocker shaft 4 '. Hydraulic pressure P to piston 8 through'a
However, the hydraulic pressure P is supplied to the piston 9 through the journal 12 and the oil passage 4a of the rocker shaft 4. The low-speed rocker arm 6 and the high-speed rocker arm 7 are pivotally supported by rocker shafts 4 ′ and 4 on both sides of the T-shaped rocker arm 5 being fitted into the shaft holes 6a and 7a at the respective base ends so as to be swingable. Roller bearings 10 and 11 are axially supported at the respective tips. These roller bearings 10 and 11 are brought into contact with the low speed cam 14 and the high speed cam 15, respectively, and roll.

In the low speed rotation range of the engine, as shown in FIG. 13, the piston 8 is pushed out from the piston hole by the spring force of the spring 17 'and its tip is fitted into the piston hole 6b of the low pressure rocker arm 6. As a result, the low-speed rocker arm 6 is coupled to the T-type rocker arm 5 to be integrated, and the valves 2 and 3 are driven by the low-speed cam 14 via the low-speed rocker arm 6 and the T-type rocker arm 5. On the other hand, the piston 9 of the high-speed rocker arm 4 is retracted by the spring force of the spring 17 and drawn into the piston hole as shown in FIG. 13, and is disengaged from the T-shaped rocker arm 5 to freely swing. It is possible.

When the engine enters the high-speed rotation range, hydraulic pressure is supplied to the oil passage 4a (FIG. 13) of the rocker shaft 4, the piston 9 is pushed out of the piston hole against the spring force of the spring 17, and the tip thereof is Fit into the piston hole 7b of the high speed rocker arm 7. As a result, the high-speed rocker arm 7 is T
Type rocker arm 5 is integrated and integrated with a high speed cam
The valves 2 and 3 are driven by the high-speed rocker arm 7 and the T-shaped rocker arm 5 by 15.

[0007]

By the way, in an engine provided with a valve mechanism in which the rocker shafts 4 and 4 ′ swing together with the T-shaped rocker arm 5 as described above, the rocker shaft support portion of the cylinder head has a bearing function. Therefore, it is necessary to provide a rocker shaft supporting method that does not prevent rocking of the rocker shaft. The rocker shaft is supported by a block type rocker shaft holder 20 as shown in FIG. 14 or a cap type rocker shaft cap 21 as shown in FIG.

However, the rocker shaft holder
In the rocker shaft cap 21, the rocker shafts are fitted to the journal parts 20a, 20a 'or 21a, 21a' respectively and fixed to the cylinder head one by one, so that the assembly is extremely difficult. However, there is a problem in that it is troublesome and the rigidity after assembly is low. The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a structure of a cylinder head in which the rocker shaft of an engine having a valve mechanism in which the rocker shaft swings together with the rocker arm can be easily assembled. .

[0009]

To achieve the above object, according to the present invention, a rocker shaft is mounted on a cylinder head of an engine equipped with a valve mechanism for rocking together with a rocker arm to support the rocker shaft. The rocker shaft cap is integrally formed with a plurality of cap portions supporting each rocker shaft and a beam portion supporting both sides of these cap portions to form a ladder frame structure, and an oil passage is provided in each beam portion. It has a different structure.

[0010]

[Function] After mounting each rocker shaft on each rocker shaft journal portion on the cylinder head side, the rocker shaft cap is mounted and fixed. As a result, the cap can be attached at once, and the workability is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In FIGS. 1 to 3, a cylinder head assembly 30 is a vertically divided two-sided cylinder head, and a lower cylinder head (hereinafter simply referred to as “cylinder head”)
31, the upper camshaft holder 32, and the cam cap 33
And a rocker shaft cap 34. A cam shaft holder 32 is placed on the cylinder head 31, and a cam cap 33 is placed on the cam shaft holder 32. The camshaft holder 32 and the cam cap 33 are attached to the cylinder head by bolts 35 and 36.
It is fixed at 31. A rocker shaft cap 34 is fixed to the lower surface of the camshaft holder 32 with bolts 37. As shown in FIG. 3, the cylinder head 31 has a combustion chamber 31a.
An intake port 31b, an exhaust port 31c, etc. are formed, and an intake valve 38, an exhaust valve 39, a spark plug (not shown), etc. are mounted in the combustion chamber 31a.

The camshaft holder 32 has a ladder frame structure as shown in FIG. 4, and has both side walls in the longitudinal direction.
Crossbars 32b connecting 32a and 32a 'are integrally formed at respective positions corresponding to the respective journals of the camshaft. A cam journal portion 32c of the intake side camshaft and a cam journal portion 32c 'of the exhaust side camshaft (FIGS. 6 and 7) are formed on both sides of the upper surface of each of these crossbars 32b. These cam journal portions 32c and 32c 'have a semicircular cross section.

Further, a journal portion 32d for pivotally supporting the rocker shaft on the intake side and a journal portion 32d 'for pivotally supporting the rocker shaft on the exhaust side are formed on the lower surface of the Kamshatov holder 32. There is. These journal portions 32d and 32d 'also have a semicircular cross section. In this way, the camshaft holder 32 is integrally formed by connecting the facing cam journal portions 32c and 32c 'on the intake side and the exhaust side. This significantly improves the rigidity of the camshaft holder 32.

On the lower surface of the cam cap 33 (FIG. 2), cam journal portions 33c and 33c 'are formed at positions corresponding to the cam journal portions 32c and 32c' of the crossbar 32b.
These cam journal portions 33c and 33c 'also have a semicircular cross section. And the cam journal parts 32c and 33c, 32c '
And 33c 'form a circular cam journal portion.

The rocker shaft cap 34 has a ladder frame structure as shown in FIG.
Caps 34a corresponding to 32 crossbars 32b
And two beam portions 34b and 34b ', which continuously connect both sides of these cap portions 34a, are integrally formed. On the upper surface of each cap portion 34a, journal portions 34d, 34d 'for pivotally supporting the rocker shaft are provided at positions corresponding to the respective journal portions 32d, 32d' of the camshaft holder 32. These journal portions 34d and 34d 'also have a semicircular cross section. And journals 32d and 34d, 32d 'and 34d'
A circular rocker shaft journal portion is formed by and.

An oil passage 34e is formed in the beam portion 34b on one side of the rocker shaft cap 34 and a beam portion 3 on the other side is formed.
Oil passages 34f and 34g are provided in 4b '. These oil passages are connected to an oil pump (not shown) and supply control oil to the variable valve timing mechanism. For example, in the variable valve timing mechanism shown in FIG. 13, the high speed rocker arm 7 is disconnected from the T-shaped rocker arm 5 by disconnecting the rocker shaft 4 and the piston 9 in the low rotation range, and the rocker shaft 4 ′ is used in the high rotation range. The low-speed rocker arm 6 is disconnected from the T-type rocker arm 5 by releasing the connection with the piston 8, or the low-speed and high-speed rocker arms on the intake side and the exhaust side of a specific cylinder are disconnected from the rocker shaft and are deactivated. .

Cylinder head 31, camshaft holder 32
The cam cap 33 is also provided with oil passages 31e, 31f, 32e, 32f, 33e, 33f, etc., as shown in FIG. The oil passage 31e of the cylinder head 31 is connected to an oil pump (not shown) and supplies the oil discharged from the oil pump to the cam journal portions 32c, 32c ′ of the camshaft holder 32.

The assembly of the camshaft, rocker shaft, etc. of the valve mechanism will be described below. Intake-side and exhaust-side valve operating mechanisms For example, after the camshafts of the variable valve timing mechanism as shown in FIG. 12 are fitted into the cam journal portions 32c, 32c ′ of the camshaft holder 32,
A cam cap 33 is mounted and pivotally supported between the two. This cam cap 33 has bolts 35, as described above.
Cylinder head 31 together with camshaft holder 32 by 36
Fixed to.

The rocker shafts of the variable valve timing mechanisms are fitted to the journal portions 32d and 32d 'of the camshaft holder 32 through bearings (not shown), and then the rocker shaft caps 34 are mounted. It is pivotally supported between these two. To assemble the rocker shaft, place the camshaft holder 32 upside down, fit the rocker shafts with the journal parts 32d and 32d 'facing upward, and then mount the rocker shaft cap 34. The rocker shafts are pivotally supported by the journal portions 34d 1 and 34d ′ of the cap portions 34a, and are fixed to the camshaft holder 31 by the bolts 37 as described above. As a result, each rocker shaft can be attached to the cylinder head 30 at once.

The camshaft holder 32 has a ladder frame structure in which the respective cam journal portions 32c and 32c 'on the intake side and the exhaust side that face each other are connected to each other, and the rocker shaft cap 34 also has a ladder frame structure. The rigidity is high, and the rigidity of the entire cylinder head assembly 30 is improved accordingly.

[0021]

As described above, according to the present invention, the rocker shaft cap mounted on the cylinder head of the engine equipped with the valve mechanism for rocking the rocker shaft together with the rocker arm to support the rocker shaft is A rocker shaft structure is formed by integrally forming a ladder frame structure by integrally forming a plurality of cap portions supporting the rocker shaft and beam portions supporting both sides of these cap portions, and providing an oil passage in each beam portion. Can be assembled to the cylinder head at a time, improving the assemblability, and the ladder frame structure improves the rigidity, which in turn improves the rigidity of the entire cylinder head assembly. Accurate operation of the valve train can be guaranteed for a long period of time. Further, by providing the oil passage in the beam portion of the rocker shaft cap, the cylinder head can be made compact, and at the same time, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partially omitted plan view of a cylinder head assembly to which the present invention is applied.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a plan view of the camshaft holder of FIG.

FIG. 5 is a side view of FIG.

FIG. 6 is an end view of FIG.

7 is a sectional view taken along the line VII-VII in FIG.

FIG. 8 is a plan view of the rocker shaft cap of FIG.

9 is a side view of FIG.

FIG. 10 is an end view of FIG.

11 is a cross-sectional view taken along the arrow line XI-XI in FIG.

FIG. 12 is an assembled perspective view showing an example of a variable valve timing mechanism.

13 is a cross-sectional view taken along the arrow line XIII-XIII in FIG.

FIG. 14 is a perspective view of a first example of a conventional rocker shaft support member.

FIG. 15 is a perspective view of a second example of a conventional rocker shaft support member.

[Explanation of symbols]

 1 Variable Valve Timing Mechanism 30 Cylinder Head Assembly 31 Cylinder Head 32 Cam Shaft Holder 33 Cam Cap 34 Rocker Shaft Cap 34a Cap Part 34b Beam Part 38, 39 Valve

Claims (1)

[Claims] 1. A rocker shaft cap that is mounted on a cylinder head of an engine equipped with a valve mechanism in which a rocker shaft swings together with a rocker arm and that supports the rocker shaft, and a plurality of cap portions that support the rocker shafts. The structure of the cylinder head is characterized in that a ladder frame structure is formed integrally with beam portions supporting both sides of the cap portion, and an oil passage is provided in each beam portion.