JPH06173625A - Engine valve operating device - Google Patents

Abstract

PURPOSE:To dispense with highly accurate work in an engine valve operating device in which plural cams are used selectively. CONSTITUTION:An engine valve operating device has two air intake valves arranged in a single cylinder, two cams 21 and 22 having mutually a different profile and two rocker arms 1 and 2 to drive so as to open and close the respective air intake valves while being driven by the respective cams 21 and 22, and has a prop 5 interposed in one rocker arm 1 so as to be displaceable, an adjusting screw 6 interposed in the other rocker arm 2 so as to vary a projecting quantity to the prop 5 and an oil chamber 40 to move the prop 5 over to a locking position to lock relative displacement of the respective rocker arms 1 and 2 and a non-locking position which does not lock the relative displacement of the respective rocker arms 1 and 2 by bringing it into contact with the adjusting screw 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve actuating device which selectively uses a plurality of cams according to engine operating conditions.

[0002]

2. Description of the Related Art Conventionally, the lift characteristic of an intake valve or an exhaust valve is made different according to the operating state for the purpose of achieving both torque during low-medium speed operation and improvement of output during high-speed operation. Alternatively, it is known to control the intake / exhaust amount (see, for example, Japanese Patent Laid-Open No. 2-78717).

To explain this, a rocker shaft for low speed, whose rocking tip abuts against the valve, and a rocker shaft for high speed, which is adjacent to one side of the rocker arm for low speed and has no contact portion with the valve, are common. A low speed rocker arm is slidably contacted with a low speed cam, and a high speed rocker arm is slidably contacted with a high speed cam having a profile such that a valve opening angle or a valve lift amount is larger than that of the low speed cam.

Further, in a swinging portion separated from the rocker shaft by a predetermined distance, in a direction parallel to the rocker shaft, a plunger responsive to the operating hydraulic pressure is fitted into the fitting hole or is pulled out from the fitting hole. The rocker arm may be connected or disconnected.

[0005]

In such a conventional device, a plurality of plungers fitted into the respective fitting holes are provided with hydraulic pressure when the fitting holes are coaxially aligned. Since it is configured to fit into the mating hole of the mating body while pushing the mating plunger, it is required that the machining accuracy of the plunger, the mating hole of the high-speed rocker arm, and the mating hole of the low-speed rocker arm be extremely high. It was necessary to co-machine the fitting hole, resulting in an increase in cost.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the productivity of a valve actuating device for selectively switching a plurality of cams according to engine operating conditions.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a plurality of valves provided in one cylinder and having the same function, a plurality of cams having different profiles, and a plurality of cams driven to open and close each valve are driven. A plurality of rocker arms, a prop that is displaceably mounted on one of the rocker arms, an adjusting member that is mounted on the other rocker arm to change the amount of protrusion with respect to the prop, and the prop is brought into contact with the adjusting member. A switching means for moving the locker arm over a locking position for locking the relative displacement and a non-locking position for locking the relative displacement of each rocker arm is provided.

[0008]

When the prop is moved to the non-locking position by the switching means, the rocker arms rotate relative to each other to open / close each valve independently according to the profile of each cam.

When the prop is moved to the locking position by the switching means, the rocker arms rotate as a unit, opening and closing the valves together according to the relatively large profile of the cams.

At the locking position of the prop, the prop is brought into contact with the adjusting member to lock the relative rotation of each rocker arm, so that a fitting hole or the like formed in each rocker arm by co-processing as in the conventional device. Is unnecessary and productivity can be improved.

By adjusting the relative position of each rocker arm locked by the prop through the adjusting member, the cam clearance of each rocker arm when the prop is in the locked position can be made appropriate. . As a result, the processing accuracy required for each rocker arm or the like can be further reduced, and the productivity can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to an engine equipped with two valves (both intake valves and exhaust valves, which are shown as intake valves) having the same function for one cylinder. An example of the case will be described.

As shown in FIGS. 1 to 6, each cylinder is provided with two rocker arms 1 and 2 corresponding to two intake valves 9. The base ends of the rocker arms 1 and 2 are swingably supported by an engine block 10 via a rocker shaft 3 common to each cylinder, and the stem tops of the intake valves 9 are in contact with the tip ends of the rocker arms 1 and 2. The valve follower 13 is inserted and inserted. Each intake valve 9 is biased in the valve closing direction by a valve spring 11 via a retainer 12.

The two cams 21 and 22 for driving the rocker arms 1 and 2 are integrally formed on a common cam shaft 20 and have different shapes so as to satisfy the valve lift characteristics required according to the operating conditions of the engine. Is formed in. That is, the large cam 22 has a profile that makes at least one of the valve lift amount and the valve opening period larger than the small cam 21. Here, the valve lift amount and the valve opening period are both increased.

Cam followers 14 and 15 made of wear-resistant material are fixed to the rocker arms 1 and 2, and a small cam 21 and a large cam 22 are in sliding contact with each cam follower 14. The width of the cam follower 15 slidingly contacting the large cam 22 is formed larger than that of the cam follower 14 slidingly contacting the small cam 21 at a predetermined ratio.

Instead of the cam followers 14 and 15, roller followers rollingly contacting the cams 21 and 22 may be rotatably connected to the rocker arms 1 and 2.

A recess 16 is formed in the center of the rocker arm 1, and the rocker arm 2 is arranged in this recess 16.

At the rocking portion separated from the rocker shaft 3 by a predetermined distance, the rocker arm 1 and the rocker arm 2 are attached.
A prop 5 that locks relative rotation with respect to is provided so as to be relatively displaceable.

A guide hole 31 for slidably accommodating the prop 5 is formed in the rocker arm 1. The guide hole 31 extends in a direction parallel to the rocker shaft 3 and is formed in a groove shape that opens in the recess 16 so as to face the rocker arm 2 in the middle thereof.

A stopper 32 is interposed between the rocker arm 1 and the prop 5. The stopper 32 locks the relative rotation of the both, and regulates the displacement amount in the direction parallel to the rocker shaft 3.

The rocker arm 2 has an adjusting screw 6 as an adjusting member for varying the amount of projection with respect to the prop 5.
Is provided. Male screw 3 on the outer circumference of the adjusting screw 6.
3 is formed on the rocker arm 2, while the male screw 33 is formed on the rocker arm 2.
A screw hole 34 for screwing is formed. The adjusting screw 6 is prevented from loosening through the lock nut 35.

The adjusting screw 6 is arranged such that its tip end faces the prop 5, and the amount of protrusion of the adjusting screw 6 with respect to the prop 5 is adjusted by loosening the lock nut 35 and adjusting the screwing position with respect to the screw hole 34. change.

It should be noted that a plurality of rod-shaped members having different sizes are prepared as adjusting members which are interposed in the rocker arm 2 and which can change the amount of protrusion with respect to the prop 5, and are selected in the fitting holes formed in the rocker arm 2. You may make it fit.

On the way of the prop 5, a recess 36 is formed which is recessed so as to engage with the tip of the adjusting screw 6. As shown in FIG. 1, the prop 5 has a non-locking position where the tip of the adjusting screw 6 faces the recess 36, and the tip of the adjusting screw 6 has the recess 3 as shown in FIG.
It is adapted to move over to a locking position facing the upper surface 37 adjacent to 6. The movement range of the prop 5 is restricted by the stopper 32.

The valve follower 14 and the adjust screw 6 provided on the rocker arm 2 are arranged at the center of the rocker arm 2 so that the distances L ₁ and L ₂ between the adjust screw 6 and each intake valve 9 in the direction parallel to the rocker shaft 3 are equal. It is arranged offset to.

As a switching means for moving the prop 5 between the non-locking position and the locking position, a plunger portion 39 for receiving hydraulic pressure is integrally formed at one end of the prop 5, and the hydraulic pressure is provided at the other end of the prop 5. A return spring 38 that opposes to is interposed.

A hydraulic chamber 40 is defined in the guide hole 31 of the rocker arm 1 behind the plunger portion 39 via a plug 41. A signal hydraulic passage 42 for guiding the operating hydraulic pressure to the hydraulic chamber 40
Are provided through the inside of the rocker arm 1 and the main rocker shaft 3.

The discharge hydraulic pressure of the oil pump is introduced into the hydraulic chamber 40 through a switching valve (not shown) during a predetermined high speed operation. The control unit that electronically controls the operation of the switching valve inputs the engine rotation signal, the cooling water temperature signal, the lubricating oil temperature signal, the intake supercharging pressure signal by the supercharger, the throttle valve opening signal, etc. Based on the detected value, the rapid change of the engine torque is suppressed and the switching of the cams 21 and 22 described later is smoothly performed.

Next, the operation will be described.

When the engine is operated at a low load and a low speed, the prop 5 is held in the non-locking position by the urging force of the return spring 38, and the recess 36 of the prop 5 is engaged with the tip of the adjusting screw 6, whereby each rocker arm is engaged. 1,
2 rotate relative to each other, and each intake valve 9 is connected to each cam 21, 22
Open and close independently according to the profile of. As a result, a difference occurs in the flow velocity of the intake air flowing through the two intake ports 18 that are opened and closed by the intake valves 9, and a mixture with a high air-fuel ratio is made to flow into the center of the combustion chamber 19 from the intake port 18 on the side of the lower flow velocity. The air-fuel mixture near the spark plug (not shown) provided in the center of the combustion chamber 19 is stratified, and the air-fuel ratio is increased from the intake port 18 on the side where the flow velocity is high. Swirl is generated in the air, and stable combustion with a lean mixture is realized.

When the operating hydraulic pressure is introduced into the hydraulic chamber 40 through the signal hydraulic passage 42 during high-load high-speed operation of the engine, the prop 5 moves to the locking position against the return spring 38 and the upper surface of the prop 5 is pushed. Adjust screw 6 to 37
By abutting the tip of each rocker arm 1,
2 rotate together and open and close each intake valve 9 together according to the profile of the large cam 22. This allows
Both the opening angle and the lift amount of each intake valve 9 become large, and high intake charging efficiency is maintained even at high speeds, and the engine generated output can be increased.

On the other hand, when the engine shifts from the high speed range to the low speed range again, the hydraulic pressure introduced into the hydraulic chamber 40 decreases due to the operation of the switching valve, and the elastic restoring force of the return spring 38 causes the prop 5 to move to the unlocked position. And the lock on the rocker arm 1 is released.

At its locking position, the prop 5 has a function of contacting the adjusting screw 6 and locking the relative rotation of the rocker arms 1 and 2, so that the prop 5 is formed by co-machining on each rocker arm as in the conventional device. It eliminates the need for fitting holes, etc., and improves productivity.

Further, by mounting the prop 5 and the return spring 38 together on the rocker arm 1 and making them into a unit, it becomes easy to disassemble and assemble the rocker arms 1 and 2, thereby improving productivity and maintainability. To be

By adjusting the screwing position of the adjusting screw 6 to the rocker arm 2, the relative rotational position at which the rocker arms 1 and 2 are locked via the prop 5 is adjusted, and the cam clearance is properly adjusted. Can be done easily. As a result, the machining accuracy required for the rocker arms 1, 2 and the like can be further reduced and the productivity can be improved.

If the amount of protrusion of the adjusting screw 6 is too large due to variations in the length of each intake valve 9 and the mounting position of the valve seat 45, the adjusting screw 6 will remain engaged with the recess 36 of the prop 5 and the return spring 6 will remain. The elastic restoring force of 38 prevents the prop 5 from moving to the unlocked position. On the contrary, if the protruding amount of the adjusting screw 6 is too small, the clearance between the adjusting screw 6 and the upper surface 37 of the prop 5 at the locking position becomes large, and abnormal noise is generated.

The adjusting screw 6 and the intake valves 9 are formed so that the distances L ₁ and L _{2 in the} direction parallel to the rocker shaft 3 are equal to each other.
Is in contact with the prop 5 and the rocker arms 1 and 2 swing together as a unit, the moments that the rocker arms 1 and 2 receive from the intake valves 9 about the prop 5 become equal. This prevents the rocker arms 1 and 2 from tilting, and the prop screw 5 of the adjusting screw 6 is prevented.
It is possible to make the distribution of the surface pressure to be uniform and prevent uneven wear or the like at the joint between the two.

[0038]

As described above, according to the present invention, a plurality of valves provided in one cylinder and having the same function, a plurality of cams having different profiles, and a plurality of cams that follow each cam to open and close each valve. A plurality of rocker arms that are driven, a prop that is displaceably interposed in one rocker arm, an adjusting member that is interposed in the other rocker arm and that allows the amount of protrusion with respect to the prop to be variable, and the prop is in contact with the adjusting member. Since the switching means for moving the relative displacement of each rocker arm to the locking position and the non-locking position to which the relative displacement of each rocker arm is not locked is provided, both rocker arms are equipped with the switching means as in the conventional device. Productivity and maintenance are improved by eliminating the need for fitting holes formed by machining and easily adjusting the cam clearance of each rocker arm through the adjustment member. It can be improved.

[Brief description of drawings]

1 shows an embodiment of the present invention and is a vertical cross-sectional view of a valve train along the line D-D in FIG.

FIG. 2 is a plan view of an engine block that also includes a valve system.

FIG. 3 is a plan view of the valve train of the same.

FIG. 4 is a transverse sectional view taken along line AA of FIG.

FIG. 5 is a transverse sectional view taken along the line BB of FIG.

FIG. 6 is a transverse sectional view taken along the line CC of FIG.

FIG. 7 is a vertical cross-sectional view of the valve train showing the prop in the locking position.

[Explanation of symbols]

 1 rocker arm 2 rocker arm 5 prop 6 adjust screw (adjustment member) 9 intake valve 21 small cam 22 large cam 38 return spring 40 hydraulic chamber

Claims (1)

[Claims] 1. A plurality of valves provided in one cylinder and having the same function, a plurality of cams having different profiles, a plurality of rocker arms that follow the cams to open and close each valve, and A prop mounted displaceably on the rocker arm, an adjusting member interposed on the other rocker arm for varying the amount of protrusion with respect to the prop, and the prop being brought into contact with the adjusting member to lock relative displacement of each rocker arm. A valve actuating device for an engine, comprising: a switching unit that moves a locking position and a relative displacement of each rocker arm to a non-locking position where the rocker arm is not locked.