JPH04284108A - Valve operating device of engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve operating device, and more particularly to an engine valve operating device that switches valve lift characteristics between low engine speed and high engine speed.

0002

[Prior Art] Conventionally, in order to achieve both high torque characteristics during low-to-medium speed operation and improved output during high-speed operation, the lift characteristics of intake valves or exhaust valves have been varied depending on the operating conditions. It is known to control the intake/exhaust timing or the intake/exhaust amount (for example, Japanese Patent Application Laid-Open No. 1983-1999)
167016, JP-A-63-57805, etc.).

These rockers have a common rocker with a low-speed rocker arm whose swinging tip contacts the valve and a high-speed rocker arm that is a free cam follower that is installed between the two low-speed rocker arms and has no contact area with the valve. The shaft is swingably supported, and the low-speed rocker arm is in sliding contact with the low-speed cam, and the high-speed rocker arm is in sliding contact with the high-speed cam, which has a profile that has a larger valve opening angle or valve lift amount than the low-speed cam. ing.

[0004] Conventionally, in such a valve actuating device, there is a device disclosed in Japanese Patent Application Laid-Open No. 1-17740 which aims to improve the ease of assembly.
A method described in Publication No. 2 is known.

In this method, a single dummy shaft that can be pushed out by the rocker shaft is inserted into each free and driving rocker arm, and the first and second driving rocker arms are removably connected using an assembly jig to connect each rocker arm. It is made into a unit, and each rocker arm is assembled to the rocker shaft in the unit state.

[0006] Before the camshaft is assembled, in order to prevent the free rocker arm from rotating beyond a predetermined amount when assembled to the rocker shaft, so-called reversal, a side surface of the free rocker arm disposed between the driving rocker arms is provided. A recessed portion is formed by cutting out the material, and a spring pin that fits into the recessed portion is press-fitted and fixed to the opposing side surface of the drive rocker arm.

[0007]

[Problems to be Solved by the Invention] However, such conventional techniques require a special assembly jig, a process of forming recesses, press-fitting pins, etc., which is troublesome and increases costs. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine valve actuation device that solves the above-mentioned conventional problems, allows easy assembly work, and reduces costs.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a rocker arm whose one end is in contact with an intake valve or an exhaust valve and which is driven by a first cam to swing around a rocker shaft; a free cam follower whose boss portion is swingably supported by a shaft supported by a rocker arm and driven by a second cam; and a connection switching means capable of switching between coupling and disconnection of the rocker arm and the free cam follower. , a valve operating device for an engine, comprising a biasing means for biasing the free cam follower toward the second cam, wherein a protrusion is provided on the boss portion of the free cam follower, and the free cam follower swings by a predetermined amount. The rocker arm is characterized in that a stopper is provided on the rocker arm, with which the protrusion comes into contact when the rocker arm is turned.

0010

According to the present invention, when assembling the rocker arm and the free cam follower to the rocker shaft, it is sufficient to first insert the shaft supported by the rocker arm through the boss portion of the free cam follower.

In this state, the free cam follower is biased by the biasing means, and even if the free cam follower attempts to rotate beyond a predetermined amount, the protrusion provided on the boss comes into contact with the stopper provided on the rocker arm.

[0012] The free cam follower is therefore prevented from swinging, or flipping, beyond a predetermined amount.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1, 2, and 3 show an engine equipped with two valves (which may be either intake valves or exhaust valves; the one shown is an intake valve) having the same function for one cylinder. An example is shown in which the present invention is applied to the case where the present invention is applied.

To explain this, each cylinder is provided with a single main rocker arm 1 corresponding to two intake valves 9. The base end of the main rocker arm 1 is swingably supported by the cylinder head via a main rocker shaft 3 common to each cylinder, and the tip of the main rocker arm 1 abuts the top of the stem of the intake valve 9.

The main rocker arm 1 has a shaft 13.
A roller 14 is rotatably supported via a needle bearing 12, and this roller 14 rolls into contact with a low-speed cam 21 as a first cam.

The main rocker arm 1 is formed into a substantially rectangular shape in plan view, and the main rocker arm 1 has a roller 1.
Alongside 4 is a sub-rocker arm 2 as a single free cam follower. The base end of this sub-rocker arm 2 is connected to the main rocker arm 1 via a sub-rocker shaft 16 so as to be relatively rotatable. The sub-rocker shaft 16 is slidably fitted into a hole 17 formed in the sub-rocker arm 2, and is press-fitted into a hole 18 formed in the main rocker arm 1.

The sub-rocker arm 2 does not have a portion that comes into contact with the intake valve 9, and a cam follower portion 2A that comes into sliding contact with a high-speed cam 22 serving as a second cam is formed at the tip of the sub-rocker arm 2 in a protruding arc shape.

A cylindrical recess 26 is formed in the main rocker arm 1, located directly below the sub-rocker arm 2, for accommodating a lost motion spring 25 as a biasing means. Coiled lost motion spring 2
The lower end of 5 is engaged with a lock washer 26B installed in an annular groove 26A formed in the recess 26, and the upper end thereof is engaged with a locking washer 26B installed in an annular groove 26A formed in the recess 26.
A cylindrical spring retainer 2 with a bottom that slidably fits into the spring retainer 2.
7 is energized.

On the other hand, the above-mentioned sub-rocker arm 2 is integrally provided with a protrusion 2B on the opposite side of the above-mentioned cam follower part 2A at its boss part, and a protrusion 2C on the lower end thereof.
is provided. The protrusion 2B has a cam 22 centered on the sub-rocker shaft 16 of the sub-rocker arm 2.
When the rotation in the direction exceeds a predetermined amount, the rocker arm 1 comes into contact with a stopper 1A formed on the rocker arm 1, and the protrusion 2C is configured to be able to come into contact with the upper surface of the spring retainer 27.

As shown in FIGS. 4 and 5, the sub-rocker arm 2 is provided with a first plunger 31 as a connection switching means that can lock the relative rotation of both the rocker arms 1 and 2.
The main rocker arm 1 is formed with holes 35 and 36 into which second and third plungers 33 and 34 are slidably fitted, respectively. An oil chamber 37 is defined behind the second plunger 33, and a return spring 38 is interposed behind the third plunger 34.

The holes 32, 35 and 36 are coaxially continuous with each other at predetermined positions and have the same diameter. Figure 5
As shown in FIG.
By simultaneously fitting the plunger 33 into the holes 35 and 32 and the first plunger 31 into the holes 32 and 36, the main rocker arm 1 and the sub-rocker arm 2 are integrated.

As shown in FIG. 4, the return spring 3
When one end of the second plunger 33 is aligned with the end surface of the hole 35 due to the biasing force 8, the plungers 31, 33 and 34 are fitted into the holes 32, 35 and 36, respectively, and the swinging of the main rocker arm 1 is restrained. It is designed not to.

At one end of the hole 36 into which the third plunger 34 fits, there is a plug 3 that locks one end of a return spring 38.
9 is press-fitted, and an air vent hole may be opened in the plug body 39 as necessary.

An oil passage 41 that guides the hydraulic pressure to the oil chamber 37 is provided through the main rocker arm 1 and the main rocker shaft 3. The main rocker arm 1 is formed with a through hole 43 whose one end opens into the oil chamber 37 and whose other end passes through a bearing surface for the main rocker shaft 3. There is an oil gallery 4 inside the rocker shaft 3.
4 is formed in the axial direction, and the main rocker arm 1 is connected from this oil gallery 44 through a through hole 46 and an annular groove 47.
It communicates with the through hole 43 of.

The discharge hydraulic pressure of the oil pump is introduced to the oil gallery 44 through a switching valve (not shown) during predetermined high-speed operation. The control unit that electronically controls the operation of the switching valve inputs engine rotation signals, cooling water temperature signals, lubricating oil temperature signals, intake boost pressure signals from the supercharger, throttle valve opening signals, etc. Based on the detected value, sudden changes in engine torque are suppressed, and switching between a low-speed cam 21 and a high-speed cam 22, which will be described later, is performed smoothly.

The low-speed cam 21 and the adjacent high-speed cam 22 are each integrally formed on a common camshaft.
They are formed in different shapes (including similar shapes with different sizes) to satisfy the valve lift characteristics required at low and high engine speeds. In other words, the high speed cam 22 has a profile that increases at least one of the valve lift amount and the valve opening period compared to the low speed cam 21. Here, both the valve lift amount and the valve opening period are increased.

In this embodiment having the above structure, when the engine is operated at low speed, the main rocker arm 1 swings according to the profile of the low speed cam 21 to open and close each intake valve 9. At this time, although the sub-rocker arm 2 is swung by the high-speed cam 22, each plunger 33, 31, and 34 is swung by the urging force of the return spring 38.
are housed in the holes 35, 32 and 36, respectively, and the movement of the main rocker arm 1 is not hindered.

On the other hand, when the hydraulic pressure is introduced into the oil chamber 37 through the oil gallery 44 and the oil passage 43 during high-speed operation of the engine, each plunger 33, 31, and 34 moves against the return spring 38. However, by fitting the second plunger 33 across the holes 35 and 32 and fitting the first plunger 34 across the holes 32 and 36, the two rocker arms 1 and 2 are connected and integrated. It will oscillate. Here, since the high-speed cam 22 is formed so that both the valve opening degree and the valve lift amount are larger than the low-speed cam 21, when it is integrated with the sub-rocker arm 2, the main The roller 14 of the rocker arm 1 is lifted off the low-speed cam 21, and each intake valve 9 is driven to open and close according to the profile of the high-speed cam 22, and both the valve opening degree and the valve lift amount become large.

On the other hand, when the engine shifts from the high speed range to the low speed range again, the hydraulic pressure led to the oil chamber 37 decreases due to the operation of the switching valve, and the elastic restoring force of the return spring 38 causes each plunger 33, 31, and 34 to moves to its original position, and the restraint of the main rocker arm 1 is released.

As a result, the torque characteristics based on the profile of the low-speed cam 21 and the torque characteristics based on the profile of the high-speed cam 22 are combined, and the torque can be increased from the low rotation range to the high rotation range.

Furthermore, when assembling the valve operating device according to this embodiment, the lost motion spring 25, spring retainer 27,
After installing the second plunger 33, return spring 38, and third plunger 34, the first
The sub-rocker arm 2 incorporating the plunger 31 is placed at a predetermined position on the rocker arm 1, and the sub-rocker arm shaft 16 is press-fitted into the hole 18 of the rocker arm 1 so as to loosely fit into the hole 17 formed in the sub-rocker arm 2.

Then, the sub-rocker arm 2 is biased by the lost motion spring 25 and tries to rotate counterclockwise as shown in FIG. is prevented. As a result, the rocker arm 1 can be easily transported in a state where the sub-rocker arm 2 is sub-assembled, and the subsequent assembly into the engine can be easily performed.

Furthermore, in this embodiment, a protrusion 2B is provided near the rocker shaft 3, which is the rocking center of the rocker arm.
, the inertial mass of the rocker arm 1 integrated with the sub-rocker arm 2 is not increased, and high-speed movement of the valve is not hindered.

Furthermore, since the speed at which the protrusion 2B collides with the rocker arm 1 is small, the anti-reversal function can be sufficiently ensured even if the protrusion 2B is formed small.

Note that the sub-rocker arm 2 is normally manufactured by forging, precision casting, or sintering, and the manufacturing cost does not change even if the protruding portion 2B is formed.

[0037]

[Effects of the Invention] As is clear from the above description, according to the present invention, a protrusion is provided on the boss portion of the free cam follower, and the protrusion comes into contact when the amount of swing of the free cam follower reaches a predetermined amount. Since the stopper is provided on the rocker arm, it is possible to prevent the free cam follower from reversing, simplify the assembly work, and reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a valve train showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1;

FIG. 4 is a longitudinal cross-sectional view taken along line IV-IV in FIG. 1, showing a state in which the main rocker arm and the sub-rocker arm are disconnected from each other.

FIG. 5 is a longitudinal cross-sectional view taken along line IV-IV in FIG. 1, showing a state in which the main rocker arm and the sub-rocker arm are connected.

[Explanation of symbols]

1 Main rocker arm 1A Stopper 2 Sub rocker arm 2B Protruding part 3 Main rocker shaft 9 Intake valve 16 Sub rocker shaft 25 Lost motion spring 27 Spring retainer

Claims (1)

[Claims] Claim 1: A rocker arm having one end in contact with an intake valve or an exhaust valve and swinging around a rocker shaft driven by a first cam, and a boss portion of the rocker arm swinging around a shaft supported by the rocker arm. a free cam follower supported and driven by a second cam; a connection switching means capable of switching between coupling and disconnection of the rocker arm and the free cam follower; and biasing the free cam follower toward the second cam. In the valve operating device for an engine, the boss portion of the free cam follower is provided with a protrusion, and the rocker arm is provided with a stopper that the protrusion comes into contact with when the amount of rocking of the free cam follower reaches a predetermined amount. An engine valve operating device characterized by: