JPH0842312A - Rocker shaft supporting structure of engine - Google Patents

Abstract

PURPOSE:To provide rocker shaft supporting structure having high productibity and maintainability by forming a regulating part which abuts on a rocker shaft so as to position the rocker shaft in relation to a cylinder head, to cam bracket bolts. CONSTITUTION:A camshaft 6 is provided above the cylinder head 1 of an engine, and openes/closes an intake valve or an exhaust valve through a rocker arm. A cam bracket 9 is tightened to the cylinder head 1 through two first/second cam bracket bolts 11, 12. An engagement hole 21 is formed on the outer circumferential surface of a rocker shaft 3, and a pin part (controlling part) 22 fitted to the engagement hole 21 is formed to the tip end of the first cam bracket bolt 11. Hereby, the rocker shaft 3 is positioned in relation to the cylinder head 1 by the first cam bracket bolt 11 so that the attachment/detachment of the rocker shaft 3 is facilitated, therefore, the productivity and maintainability thereof can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved rocker shaft support structure for an engine.

[0002]

2. Description of the Related Art In an automobile engine or the like, when the number of intake / exhaust valves is increased and a variable valve operating device for switching cams is provided, the number of parts assembled on a cylinder head is reduced. This tends to increase the productivity and maintainability (see Japanese Utility Model Laid-Open No. 60-112605).

In an automobile engine or the like, when the hydraulic oil is guided through the internal passage of the rocker shaft, the rocker shaft is connected to the cylinder head in order to connect the internal passage of the rocker shaft to the oil passage on the cylinder head or rocker arm side. It needs to be fixedly supported.

As a rocker shaft support structure provided in a conventional engine, there is, for example, one shown in FIG.

To explain this, the rocker arm 2 swingably supported by the rocker shaft 3 is provided with a mechanism for switching between a low speed cam and a high speed cam provided on a cam shaft (not shown). It is operated by the hydraulic pressure introduced through the internal passage of the rocker shaft.

The rocker shaft 3 is provided so as to be fitted in the cylinder head 1 in the axial direction, and a positioning dedicated pin 4 for positioning the rocker shaft 3 with respect to the cylinder head 1 is provided.

The positioning pin 4 is press-fitted into the cylinder head 1 so that the tip of the pin 4 is inserted into the rocker shaft 3.
The rocker shaft 3 is positioned in the rotational direction and the axial direction with respect to the cylinder head 1 by fitting it into the hole 5 formed in the cylinder head 1, so that the internal passage of the rocker shaft 3 is connected to the oil passage on the cylinder head or rocker arm side. It has become.

[0008]

However, in such a conventional apparatus, since it is necessary to assemble the positioning dedicated pin 4 on the cylinder head 1, it is necessary to secure a space for assembling the dedicated pin 4. At the same time, the number of parts to be assembled on the cylinder head 1 increases, which may deteriorate productivity.

Further, since the positioning-dedicated pin 4 is press-fitted into the cylinder head 1, it is troublesome to remove the pin 4 when removing the rocker shaft 3 from the cylinder head 1, which deteriorates maintainability. Can be considered.

In the present invention, attention is paid to the above problems, productivity,
An object of the present invention is to provide a rocker shaft support structure with high maintainability.

[0011]

According to the first aspect of the present invention,
A rocker arm that is rockably supported by a rocker shaft, a cam shaft that rocks the rocker arm to open / close an intake / exhaust valve, a cam bracket that rotatably supports the cam shaft, and a cam bracket that is fastened to the cylinder head. In the engine including the cam bracket bolt, the restricting portion that contacts the rocker shaft with the cam bracket bolt and positions the rocker shaft with respect to the cylinder head is formed.

According to a second aspect of the present invention, a rocker arm swingably supported by a rocker shaft, a cam shaft swinging the rocker arm to open / close the intake / exhaust valve, and a cam shaft rotatably supported. In an engine including a cam bracket and a cam bracket bolt for fastening the cam bracket to the cylinder head, a rocker shaft mounting hole for fitting the rocker shaft to the cylinder head is formed, and a screw hole for screwing the cam bracket bolt is formed in the rocker shaft. Position the rocker shaft with respect to the cylinder head by opening it in the mounting hole and forming a concave engagement hole on the rocker shaft facing the screw hole and fitting it into the rocker shaft engagement hole at the tip of the cam bracket bolt. Forming a pin portion for performing.

According to a third aspect of the present invention, a rocker arm swingably supported by a rocker shaft, a cam shaft swinging the rocker arm to open and close an intake / exhaust valve, and a cam shaft rotatably supported. In an engine including a cam bracket and first and second cam bracket bolts for fastening both ends of the cam bracket to a cylinder head, the rocker shaft is positioned with respect to the cylinder head by contacting the rocker shaft with the first cam bracket bolt. A restriction portion is formed, and the axial length of the first cam bracket bolt is set longer than that of the second cam bracket bolt.

According to a fourth aspect of the present invention, a rocker arm swingably supported by a rocker shaft, a cam shaft swinging the rocker arm to open and close an intake / exhaust valve, and a cam shaft rotatably supported. In an engine including a cam bracket and first and second cam bracket bolts for fastening both ends of the cam bracket to a cylinder head, the rocker shaft is positioned with respect to the cylinder head by contacting the rocker shaft with the first cam bracket bolt. A restriction portion is formed, and the first cam bracket bolt is arranged closer to the rotation center of the cam shaft than the second cam bracket bolt.

[0015]

According to the first aspect of the invention, the rocker arm slidably contacts the cam and swings with the rotation of the cam shaft to open / close the intake / exhaust valve.

The cam bracket is fastened to the cylinder head via cam bracket bolts, and rotatably supports the cam shaft.

The rocker shaft is positioned with respect to the cylinder head by abutting the regulating portion of the cam bracket bolt, and is fixedly supported with respect to the cylinder head.

As described above, since the function of fastening the cam bracket to the cam bracket bolt and the function of positioning the rocker shaft are provided together, it is not necessary to provide a pin dedicated to positioning in the conventional device, and the rocker shaft is detachable. Can be easily performed, productivity and maintainability can be improved, and the number of parts interposed in the cylinder head can be reduced to reduce the cost of the product.

According to the second aspect of the present invention, when the rocker shaft is assembled, the rocker shaft is fitted in the rocker shaft mounting hole of the cylinder head, and the cam bracket bolt is inserted through the cam bracket to make the screw hole of the cylinder head. Screw it on. As a result, the pin portion formed at the tip of the cam bracket bolt penetrates the screw hole and fits into the engagement hole of the rocker shaft, and the rocker shaft is positioned with respect to the cylinder head through the pin portion.
That is, the rocker shaft is restricted from being displaced in the radial direction by fitting it into the rocker shaft mounting hole of the cylinder head, and the pin portion of the cam bracket bolt is fitted into the engaging hole so that the rocker shaft is displaced in the rotational direction and the axial direction. Is regulated and is fixedly supported with respect to the cylinder head.

Since the function of fastening the cam bracket to the cam bracket bolt and the function of positioning the rocker shaft are both provided in this manner, it is not necessary to provide a pin dedicated to positioning in the above-mentioned conventional device, and the rocker shaft can be attached and detached. Can be easily performed, productivity and maintainability can be improved, and the number of parts interposed in the cylinder head can be reduced to reduce the cost of the product.

According to the third aspect of the invention, the rocker shaft is positioned with respect to the cylinder head by contacting the regulating portion of the cam bracket bolt.
It is fixedly supported on the cylinder head. Since the function of fastening the cam bracket to the cam bracket bolt and the function of positioning the rocker shaft are provided together, there is no need to provide a pin for positioning in the conventional device, and the rocker shaft can be easily attached and detached. And the maintainability are improved, and the number of parts inserted in the cylinder head is reduced to reduce the cost of the product.

As the cam shaft rotates, the cam slides on the rocker arm to rock the rocker arm, and when the intake / exhaust valve is opened / closed, the reaction force acting on the cam from the rocker arm is located above the rocker shaft. Thus, the first cam bracket bolt located in the reaction force acting direction acts more largely than the second cam bracket bolt.

By setting the axial length of the first cam bracket bolt longer than that of the second cam bracket bolt, the spring constant of the first cam bracket bolt is lowered, and the axial force of tightening the first cam bracket bolt with respect to the cam bracket is reduced. Variation can be suppressed to a small level.

According to another aspect of the invention, the rocker shaft is positioned with respect to the cylinder head by contacting the regulating portion of the cam bracket bolt.
It is fixedly supported on the cylinder head. Since the function of fastening the cam bracket to the cam bracket bolt and the function of positioning the rocker shaft are provided together, there is no need to provide a pin for positioning in the conventional device, and the rocker shaft can be easily attached and detached. And the maintainability are improved, and the number of parts inserted in the cylinder head is reduced to reduce the cost of the product.

As the camshaft rotates, the cam slides on the rocker arm to swing the rocker arm, and when the intake / exhaust valve is opened / closed, the reaction force acting on the cam from the rocker arm is located above the rocker shaft. Thus, the first cam bracket bolt located in the reaction force acting direction acts more largely than the second cam bracket bolt.

By disposing the first cam bracket bolt closer to the rotation center of the cam shaft than the second cam bracket bolt, the bending stress acting on the cam bracket can be suppressed to be small and the support rigidity of the cam shaft can be increased.

[0027]

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

As shown in FIGS. 1 and 2, a cam shaft 6 is provided on the cylinder head 1 of the engine, and the cam shaft 6 is rotationally driven in synchronization with the rotation of the engine, and a cam 7 formed on the cam shaft 6 is provided. The intake valve 8 or the exhaust valve is opened / closed via a rocker arm 2 that slides in contact with and swings.

A bearing portion 13 for supporting the camshaft 6 is formed on the cylinder head 1. A cam bracket 9 that rotatably supports the cam shaft 6 is fastened to the cylinder head 1 with the bearing portion 13.

The cam bracket 9 is attached to the cylinder head 1.
It is fastened via the first and second cam bracket bolts 11 and 12 of the book. Holes 2 for inserting the first and second cam bracket bolts 11 and 12 into both ends of the cam bracket 9.
6 and 27 are formed, and the cylinder head 1 has screw holes 1 into which the first and second cam bracket bolts 11 and 12 are screwed.
4, 15 are formed.

A rocker shaft 3 is provided to which the base end of the rocker arm 2 is slidably fitted. Rocker arm 2
Is rockably supported on the cylinder head 1 via a rocker shaft 3.

A rocker shaft mounting hole 16 into which the rocker shaft 3 is fitted is formed in the cylinder head 1. The rocker shaft 3 is fitted in the rocker shaft mounting hole 16 from the axial direction, so that the radial displacement thereof is restricted.

An engaging hole 21 is formed on the outer peripheral surface of the rocker shaft 3.
Is formed, and a pin portion (regulating portion) 22 that fits into the engagement hole 21 is formed at the tip of the first cam bracket bolt 11. By fitting the pin portion 22 of the first cam bracket bolt 11 into the engagement hole 21 of the rocker shaft 3, displacement of the rocker shaft 3 in the axial direction and the rotation direction is restricted.

By thus positioning the rocker shaft 3 via the pin portion 22 of the first cam bracket bolt 11, the internal passage 1 of the rocker shaft 3 is positioned.
0 is connected to the oil passage on the cylinder head 1 or rocker arm 2 side.

The first cam bracket bolt 11 is arranged on a line passing through substantially the center of the rocker shaft 3. The screw hole 14 for the first cam bracket bolt 11 formed in the cylinder head 1 is arranged below the cam shaft 6 with respect to the screw hole 15 for the second cam bracket bolt 12, and the lower end of the screw hole 14 has a lower end. To the rocker shaft mounting hole 16 for the. This allows
The first cam bracket bolt 11 penetrates the screw hole 14 and faces the rocker shaft mounting hole 16.

The distance m ₁ of the first cam bracket bolt 11 to the rotation center of the cam shaft 6 is set smaller than the distance m _{2 of} the second cam bracket bolt 12 to the rotation center of the cam shaft 6.

The length L ₁ under the neck of the first cam bracket bolt 11 is set to be longer than the length L ₂ under the neck of the second cam bracket bolt 12 at a predetermined ratio. The height S of the bearing surface 23 of the cam bracket 9 with respect to the first cam bracket bolt 11
₁ is a seat surface 24 for the second cam bracket bolt 12.
Is set higher than the height S ₂ . The lengths h ₁ and h ₂ of the screw holes 14 and 15 into which the first and second cam bracket bolts 11 and 12 of the cam bracket 9 are screwed are set to be substantially equal.

With the above construction, the operation will be described below.

When the rocker shaft 3 is assembled, first, the rocker shaft 3 is fitted into the rocker shaft mounting hole 16 formed in the cylinder head 1 from the axial direction, and the first cam bracket bolt 11 is inserted into the hole of the cam bracket 9. 26 is inserted and screwed into the screw hole 14 of the cylinder head 1. The pin portion 22 of the first cam bracket bolt 11 penetrates the screw hole 14 and fits into the engagement hole 21 of the rocker shaft 3 in a state where the first cam bracket bolt 11 is screwed to fasten the cam bracket 9. The rocker shaft 3 is positioned with respect to the cylinder head 1 via the pin portions 22.

On the contrary, when removing the rocker shaft 3,
The first cam bracket bolt 11 is retracted with respect to the screw hole 14 to release the engagement of the pin portion 22 with the engagement hole 21 of the rocker shaft 3, and then the rocker shaft 3 from the rocker shaft mounting hole 16 of the cylinder head 1. It is designed to be pulled out in the axial direction.

In this way, the rocker shaft 3 is positioned with respect to the cylinder head 1 by the first cam bracket bolts 11 for fastening the cam bracket 9, so that the rocker shaft 3 can be easily attached and detached, and productivity and maintainability are improved. Can be increased.

Further, it is not necessary to provide a pin for exclusive use in positioning in the conventional device, and the number of parts interposed in the cylinder head 1 can be reduced to reduce the cost of the product.

When the cam 7 of the camshaft 6 pushes down the rocker arm 2, the reaction force F acting from the rocker arm 2 to the cam 7 is the second cam bracket bolt 11 toward the first cam bracket bolt 11 in the acting direction. Greatly works as compared to 12.

The seating surface 23 of the cam bracket 9 for the first cam bracket bolt 11 is arranged relatively high, and the lower end of the screw hole 14 is opened in the rocker shaft mounting hole 16 for the rocker shaft 3 so as to be arranged at the lowest position. Therefore, the axial length of the first cam bracket bolt 11 can be set sufficiently long. In this way, the axial length of the first cam bracket bolt 11 is increased, so that the spring constant of the first cam bracket bolt 11 is reduced and the tightening axial force of the first cam bracket bolt 11 with respect to the cam bracket 9 is reduced. Variation can be suppressed to a small level.

The distance m ₁ of the first cam bracket bolt 11 to the rotation center of the cam shaft 6 is set smaller than the distance m _{2 of} the second cam bracket bolt 12 to the rotation center of the cam shaft 6, By making 11 closer to the camshaft 6, the bending stress acting on the cam bracket 9 is suppressed to a small level, and the camshaft 6
The support rigidity of can be increased.

[0046]

As described above, according to the first aspect of the present invention, the rocker arm swingably supported by the rocker shaft, the cam shaft swinging the rocker arm to open / close the intake / exhaust valve, and the cam. In an engine including a cam bracket that rotatably supports the shaft and a cam bracket bolt that fastens the cam bracket to the cylinder head, a restricting portion that abuts the rocker shaft on the cam bracket bolt and positions the rocker shaft with respect to the cylinder head. Since it is formed, it is not necessary to provide a pin dedicated to positioning in the conventional device, the rocker shaft can be easily attached and detached, productivity and maintainability can be improved, and the number of parts interposed in the cylinder head can be reduced. Product cost can be reduced.

According to a second aspect of the present invention, a rocker shaft mounting hole for fitting a rocker shaft to the cylinder head is formed, and a screw hole for screwing a cam bracket bolt into the cylinder head is opened in the rocker shaft mounting hole. The shaft has an engaging hole that is recessed to face the screw hole, and the tip of the cam bracket bolt is fitted with the engaging hole of the rocker shaft to form the pin part that positions the rocker shaft with respect to the cylinder head. When the cam bracket bolt fastens the cam bracket, the pin formed at the tip of the cam bracket penetrates the screw hole and fits into the engagement hole of the rocker shaft to position the rocker shaft. Can be easily attached and detached to improve productivity and maintainability, and the number of parts to be inserted in the cylinder head By reducing the cost down of the product can be achieved.

According to the third aspect of the present invention, the rocker arm is swingably supported by the rocker shaft, the cam shaft swings the rocker arm to open / close the intake / exhaust valve, and the cam shaft is rotatably supported. In an engine including a cam bracket and first and second cam bracket bolts for fastening both ends of the cam bracket to a cylinder head, the rocker shaft is positioned with respect to the cylinder head by contacting the rocker shaft with the first cam bracket bolt. Since the regulation part is formed and the axial length of the first cam bracket bolt is set longer than that of the second cam bracket bolt, it is not necessary to provide a pin dedicated to positioning in the conventional device, and the rocker shaft can be easily attached / detached. Performance and maintainability are enhanced, and a large load is applied to the first The bracket bolt axial length can be set longer than the second cam bracket bolt, and the spring constant of the first cam bracket bolt can be reduced to minimize variations in the axial tension of the first cam bracket bolt against the cam bracket. To be

According to a fourth aspect of the present invention, the first cam bracket bolt is formed with a restricting portion that abuts against the rocker shaft to position the rocker shaft with respect to the cylinder head, and the first cam bracket bolt is used as a center of rotation of the camshaft. On the other hand, since it is arranged closer to the second cam bracket bolt, it is not necessary to provide a pin dedicated to positioning in the conventional device, the rocker shaft can be easily attached and detached, productivity and maintainability can be improved, and a large load can be applied. The first cam bracket bolt can be arranged closer to the rotation center of the cam shaft than the second cam bracket bolt, and bending stress acting on the cam bracket can be suppressed to be small, and the supporting rigidity of the cam shaft can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view of an engine showing an embodiment of the present invention.

FIG. 2 is a sectional view of an engine including a rocker arm and the like.

FIG. 3 is an exploded perspective view of an engine showing a conventional example.

[Explanation of symbols]

 1 cylinder head 2 rocker arm 3 rocker shaft 6 cam shaft 8 intake valve 9 cam bracket 11 first cam bracket bolt 12 second cam bracket bolt 14 screw hole 16 rocker shaft mounting hole 21 engagement hole 22 pin part

Claims (4)

[Claims] 1. A rocker arm swingably supported by a rocker shaft, a cam shaft swinging the rocker arm to open / close an intake / exhaust valve, a cam bracket rotatably supporting the cam shaft, and a cam bracket. A rocker shaft support for an engine, comprising: a cam bracket bolt for fastening the cylinder head to a cylinder head; and a restricting portion for positioning the rocker shaft with respect to the cylinder head by contacting the cam bracket bolt with the rocker shaft. Construction. 2. A rocker arm swingably supported by a rocker shaft, a cam shaft that swings the rocker arm to open and close an intake / exhaust valve, a cam bracket that rotatably supports the cam shaft, and a cam bracket. In an engine equipped with a cam bracket bolt that fastens to the cylinder head, a rocker shaft mounting hole for fitting the rocker shaft to the cylinder head is formed, and a screw hole for screwing the cam bracket bolt is opened in the rocker shaft mounting hole. , The rocker shaft is formed with an engaging hole that is recessed in confrontation with the screw hole, and the tip of the cam bracket bolt is fitted into the engaging hole of the rocker shaft and the pin part that positions the rocker shaft with respect to the cylinder head is installed. A rocker shaft support structure for an engine characterized by being formed. 3. A rocker arm rockably supported by a rocker shaft, a cam shaft rocking the rocker arm to open / close an intake / exhaust valve, a cam bracket rotatably supporting the cam shaft, and a cam bracket. In an engine that includes first and second cam bracket bolts that fasten both ends of the rocker shaft to the cylinder head, a restricting portion that positions the rocker shaft with respect to the cylinder head by contacting the rocker shaft with the first cam bracket bolt is formed. An engine rocker shaft support structure in which the shaft length of the first cam bracket bolt is set longer than that of the second cam bracket bolt. 4. A rocker arm swingably supported by a rocker shaft, a cam shaft swinging the rocker arm to open / close an intake / exhaust valve, a cam bracket rotatably supporting the cam shaft, and a cam bracket. In an engine that includes first and second cam bracket bolts that fasten both ends of the rocker shaft to the cylinder head, a restricting portion that positions the rocker shaft with respect to the cylinder head by contacting the rocker shaft with the first cam bracket bolt is formed. A rocker shaft support structure for an engine, wherein the first cam bracket bolt is arranged closer to the rotation center of the cam shaft than the second cam bracket bolt.