JPH0748962Y2 - Engine valve gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) This invention has, for example, two intake valves and one exhaust valve per cylinder, and a coil spring is stretched between adjacent intake side rocker arms that swing in the same phase. The present invention relates to a valve operating device for an engine such as a SOHC (single overhead camshaft) engine.

(Prior Art) Conventionally, as a valve operating system for the engine of the above-mentioned example, for example,
There is an apparatus described in Japanese Utility Model Laid-Open No. 61-108803.

That is, on the same rocker shaft on the intake side, there are slippers as cam-side contact portions and tappet adjust screws as valve-side contact portions at both ends on the lower side,
In addition, the engine valve operating device is provided with rocker arms that oscillate in the same phase next to each other and a coil spring between the rocker arms.

The coil spring described above is generally constructed as shown in FIG.

That is, in order to swing the two rocker arms 42 and 43 on the same rocker shaft 41 in phase, the coil spring 4
Both end faces of 4 are end face processed by cutting a portion indicated by an imaginary line α in the figure.

However, when the end face processing is applied to the coil spring 44 in this way, the rocker arms 42 and 43 can be forcibly swung by the cam and the valve stem. When the 42, 43 rock at high speed, the movement of the coil spring 44 is delayed with respect to the rocking of the rocker arms 42, 43, and as a result, a relative deviation occurs between the rocker arms 42, 43 and the coil spring 44. Then, there is a problem that abnormal wear occurs due to the friction between the rocker arms 42 and 43 facing each other due to friction with the spring.

In order to solve such a problem, for example, as shown in FIG. 4, both ends of the above-mentioned coil spring 44 are bent into a substantially L shape to form bent portions 45, 45, and the rocker arm 42 is formed. The bent portions 45, 45 described above are provided on the end faces of the
It suffices to form the insertion holes 46, 46 for inserting the insertion holes 46, 46 and insert the bent portions 45, 45 into the insertion holes 46, 46. In this case, the number of processing steps such as bending for the coil spring 44 is increased. Is increasing,
Not only is the structure complicated and the cost is high, but there is a problem that the presence of the above-mentioned bent portions 45, 45 hinders the commonization of the coil spring 44 on the exhaust side.

(Object of the Invention) This invention is a valve operating system for an engine, which is provided with rocker arms having contact portions on both sides on which a cam pressing force and a reaction force of a valve spring act on a swing center, and the abutting portions are adjacent to each other. By controlling the rotation of the coil spring between the rocker arms that oscillate in phase with the rocker arm at the low load part of the rocker arm, the above-mentioned abnormal wear of the rocker arm is ensured without increasing the rigidity of the rocker arm and without increasing the processing man-hours. An object of the present invention is to provide a valve operating system for an engine that can be prevented.

(Structure of the Invention) In this invention, a rocker arm having a substantially cylindrical boss portion that is loosely fitted to a rocker shaft, and a cam contact portion and a valve contact portion is provided on both sides of the boss portion. ,
The rocker arms oscillating in the same phase on the same rocker shaft are arranged next to each other, and a coil spring that is loosely fitted to the rocker shaft and is arranged between both boss portions of the adjacent rocker arms is provided. Due to the pressing force of the cam acting on both contact portions and the reaction force of the valve spring, a part of the peripheral surface range in the sliding contact surface between the rocker shaft and the boss is higher than the other peripheral surface ranges. A valve operating device for an engine configured to receive a load, wherein the coil spring has both ends having the same shape as an intermediate portion and both ends of the coil spring assembled in the rocker shaft. The positions of the parts are formed so as to fall within the other circumferential surface range, and the side surfaces of the two boss portions, which both end portions of the coil spring abut, face each other in the other circumferential surface range. Wherein the notch-shaped engaging groove for engaging the ends of the coil spring in the circumferential direction is the valve gear of the formed engine.

(Effect of the Invention) According to the present invention, both ends of the above coil spring are set to the same shape as the intermediate portion by simply cutting the both ends without performing end face processing or bending processing on the both ends. Since the engaging grooves for locking the parts are formed on both surfaces of the rocker arm that face each other, the coil spring end portion and the engaging groove are engaged with each other without increasing the number of processing steps, and thus the coil spring There is an effect that rotation is regulated and abnormal wear of the rocker arm can be surely prevented.

Further, since the above-mentioned engaging groove is formed in a low load portion where surface pressure is low and high rigidity is not required, avoiding a portion where surface pressure becomes high with respect to the rocker shaft, without increasing the rigidity of the rocker arm, The above effects can be obtained.

To further elaborate on this point, in the engine valve operating device having the above configuration, the rocker arm is originally pushed up in the resultant force direction by the resultant force of the cam pressing force and the reaction force of the valve spring at the time of valve lift, and Since the rocker arm itself is swinging, the pressing load in the above-mentioned part of the peripheral surface area is increased. For this reason, the surface pressure becomes high in the part of the peripheral surface range, that is, the range of the sliding contact surface where the rocker shaft and the rocker arm are in sliding contact, and the abnormal friction is affected.

Further, the rigidity of the boss portion forming the peripheral surface of the portion corresponding to the above-mentioned partial peripheral surface range needs to be high so as not to change the circular shape of the peripheral surface in order to support a high load.

In contrast to the restriction of the above-mentioned part of the peripheral surface range, since the restriction is not applied to the other peripheral surface range, both ends of the coil spring are locked in the peripheral direction in the other peripheral surface range. The above effect can be obtained by forming the engagement groove.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

The drawings show a valve train of a SOHC engine. In FIGS. 1 and 2, this engine has two intake valves 1
It has one and one exhaust valve 2.

A cylinder head 5 provided with the intake ports 3 and 3 and the exhaust port 4 which are opened and closed by the intake valves 1 and 1 and the exhaust valve 2 is provided, and the cylinder head cover 7 is provided on the top deck of the cylinder head 5 via the gasket 6. It is installed.

Further, a cam shaft 10 having a large number of cams 8, 9 ... Is mounted along the cylinder row direction, and an intake side rocker shaft 11 and an exhaust side rocker shaft 11 are provided above the cam shaft 10.
12 and 12 are arranged in parallel with each other.

The rocker shafts 11 and 12 described above are fixed to the cylinder head 5 side through arm shaft supporters 13 ... Shown in FIG.

Between the boss portions 13a, 13a on one side of the arm shaft supporter 13 of the rocker shaft 11 on the intake side of the above rocker shafts 11, 12, rocker arms 14, 14 swinging in the same phase side by side are arranged. , These two rocker arms 14,14
A coil spring 15 is arranged between them.

On the other hand, a rocker arm 16 and a coil spring 17 are arranged between the boss portions 13b, 13b on the other side of the arm shaft supporter 13 of the rocker shaft 12 on the exhaust side.

The intake-side rocker arm 14 includes the slipper 18 that abuts the cam 8 at both end portions on the lower side, and the valve stem of the intake valve 1.
19 Hydraulic lash adjuster that abuts on the upper end 20
The rocker arm 16 on the exhaust side, which has a so-called HLA, similarly has a slipper that abuts the cam 9 at both ends on the lower side.
21 and a hydraulic crush adjuster 23 that comes into contact with the upper end of the valve stem 22 of the exhaust valve 2.

Here, each of the above-mentioned valve stems 19 and 22 is a valve rod arranged at a predetermined portion of the cylinder head 5 via valve guides 24 and 24, and a split collet is provided at the upper end of each of these valve stems 19 and 22. The spring retainers 26, 26 are fitted via 25, 25, and the valve springs 28, 27 are fitted between the spring seats 27, 27 of the cylinder head 5 and the lower surfaces of the above spring retainers 26, 26.
28 is suspended.

That is, the engine valve gear having the above-described structure receives the pressing force of the cam 8 acting on both the contact portions 18 and 20 (slippers, see HLA) and the reaction force of the valve spring 28 during valve lift, A part of the peripheral surface area within the sliding contact surface between the rocker shaft 11 and the boss portion 14a is configured to receive a higher load than other peripheral surface areas.

By the way, on the both end surfaces of the boss portions 14a, 14a of the rocker arms 14, 14 on the intake side that swing in the same phase as described above side by side, the low load portion above the axis of the rocker shaft 11 (other circumferences Surface area), the above-mentioned coil spring 15
As shown in FIG. 1, the engaging grooves 29, 29 for locking both end portions of the coil spring are formed in a range of, for example, about 90 degrees, and slightly inclined in correspondence with the pitch angle of the coil spring 15 as shown in FIG. It is formed into a shape.

That is, the engagement groove 29 described above is formed in a wedge shape that gradually becomes deeper in the circumferential direction.

Further, the coil spring 15 described above is set to the same shape as the intermediate portion shape by simply cutting the both ends without performing any end face processing and bending processing on both ends, and the both end portions are engaged with each of the above-described engagements. It is engaged with the grooves 29, 29.

In this embodiment, the intake-side rocker arms 14, 14 and the exhaust-side rocker arm 16 have the same shape so that the rocker arm can be used in common, and the coil spring 15 and the exhaust-side rocker shaft 11 arranged on the intake-side rocker shaft 11 can be provided. The coil springs 17 arranged on the rocker shaft 12 have the same shape so that the coil springs are commonly used.

The coil spring 17 on the exhaust side is, as shown in FIG. 2, an arm shaft supporter of the rocker shaft 12.
It is stretched between the end surface of the boss portion 13b of 13 and the end surface of the flat boss portion 16a of the rocker arm 16 on the side where the engagement groove 29 is not formed.

The illustrated embodiment is configured as described above, and the operation will be described below.

When the rocker arms 14, 14 on the intake side swing at high speed in the same phase, both ends of the coil spring 15 are engaged with the engaging groove 2
Since it is engaged with 9,29 and moves integrally with the rocker arms 14 and 14, between the rocker arm 14 and the coil spring 15,
No relative deviation occurs. For this reason, the Rocker Arm 14
Abnormal wear of the end faces can be reliably prevented.

The coil spring 17 on the exhaust side is stretched while the arm shaft supporter 13 on the fixed side and the rocker arm 16 on the rocking side are in phase with each other.
Since the rocker arm 16 is held by the spring force, the wear of the rocker arm 16 beyond the initial wear in which the contact with the coil spring 17 changes from point contact to line contact does not occur.

By the way, both ends of the above-mentioned coil spring 15 have the same shape as the intermediate shape (same coil cross section) by simply cutting off both ends without any end face processing and bending processing.
Since the both ends are engaged with the engagement grooves 29, 29 described above, it is possible to prevent the above effect, that is, abnormal wear of the end faces of the rocker arms 14, 14 without increasing the number of processing steps. Moreover, the spring cost can be reduced.

In addition, the above-mentioned engagement groove 29 avoids the lower surface of the rocker arm (a part of the peripheral surface range) where the surface pressure is higher than that of the rocker shaft 11, so that the surface pressure is low and high rigidity is not required. Since the rocker arm 14 is formed in the low load portion (another peripheral surface range) above the core, the above effect can be obtained without increasing the rigidity of the rocker arm 14.

That is, in the engine valve operating device having the above-mentioned configuration, the rocker arm 14 is pushed up in the resultant force direction by the resultant force of the cam pressing force and the reaction force of the valve spring 28 originally at the time of valve lift, and the rocker arm 14 itself. Since the oscillates, the pressing load in the above-mentioned part of the peripheral surface area increases. For this reason, the surface pressure becomes high in the partial peripheral surface range, that is, the range of the sliding contact surface where the rocker shaft 11 and the rocker arm 14 are in sliding contact with each other, and abnormal friction is affected. The rigidity of the boss portion 14a forming the peripheral surface of the portion corresponding to the peripheral surface range needs to be high so as not to change the circular shape of the peripheral surface in order to support a high load. For the restriction of the peripheral surface range of, since the other peripheral surface range is not subject to such restriction,
By forming the engagement groove 29 that locks both ends of the coil spring 15 in the circumferential direction in the other circumferential surface range, the above-described effect can be obtained.

In the correspondence between the configuration of the present invention and the above-described embodiment, the contact portion with the cam of the present invention corresponds to the slipper 18 of the embodiment, and similarly, the contact portion with the valve side is hydraulic. The notch-shaped engagement groove corresponds to the lash adjuster 20 and corresponds to the wedge-shaped engagement groove 29, but the invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

 The drawings show one embodiment of the present invention, FIG. 1 is a longitudinal sectional view showing a valve operating system of an SOHC engine, FIG. 2 is a plan view of an essential part of FIG. 1, and FIG. 3 is a conventional valve operating system. FIG. 4 is a partial plan view showing the same, and FIG. 4 is a partial plan view showing a conventional valve train. 1 ... Valve 8 ... Cam 11 ... Rocker Shaft 14 ... Rocker Arm 14a ... Boss 15 ... Coil Spring 18 ... Slipper (Abutment) 20 ... Hydraulic Crush Adjuster (Abutment) 29 ... Engagement Groove

Claims (1)

[Scope of utility model registration request] 1. A substantially cylindrical boss portion (14a) loosely fitted to a rocker shaft (11), a contact portion (18) with a cam (8) on both sides of the boss portion (14a), and a valve (). 1) is provided with a rocker arm (14) having a contact portion (20), and the rocker arms (14) (14) swinging in the same phase on the same rocker shaft (11) are arranged side by side. A coil spring (15), which is loosely fitted to the rocker shaft (11) and is arranged between both boss portions (14a) (14a) of the adjacent rocker arms (14) (14), is provided so that both the above-mentioned both ends when the valve is lifted. The sliding contact surface between the rocker shaft (11) and the boss portion (14a) receives the pressing force of the cam (8) acting on the contact portions (18) and (20) and the reaction force of the valve spring (28). Of an engine configured such that some of its surface areas are subjected to higher loads than others. A valve device, wherein both ends of the coil spring (15) have the same shape as an intermediate portion, and the rocker shaft (11).
Both boss portions (14a) (14a) which are formed so that the positions of the both end portions in the state of being assembled with the coil spring (15) contact the both end portions of the coil spring (15). A valve operating device for an engine, in which notch-shaped engaging grooves (29) for circumferentially locking both ends of the coil spring (15) in the other peripheral surface range are formed on the side surfaces facing each other.