JP2893748B2 - Engine Valve Actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve operating device for an engine, and more particularly to a device for switching a valve lift characteristic between a low rotation speed and a high rotation speed of an engine.

(Prior art) Conventionally, for the purpose of achieving both torque at low and medium speed operation and improvement of output at high speed operation, the lift characteristics of the intake valve or the exhaust valve are changed according to the operation state, and thereby the timing of intake and exhaust. Alternatively, it is known to control the amount of intake and exhaust (see, for example, JP-A-63-167016 and JP-A-63-57805).

To explain this, a rocker arm for low speed whose swinging tip contacts the valve and a rocker arm for high speed that is adjacent to one side of the rocker arm for low speed but has no contact portion with the valve are rocked on a common rocker shaft. The low-speed rocker arm is slidably contacted with a low-speed cam, and the high-speed rocker arm is slidably contacted with a high-speed cam having a profile in which the valve opening angle or valve lift is larger than that of the low-speed cam.

Further, in a direction parallel to the rocker shaft at a rocking portion separated from the rocker shaft by a predetermined distance, the two rocker arms are connected by a plunger responsive to the operating oil pressure being fitted into or out of the fitting hole. And their connections are broken.

(Problems to be Solved by the Invention) By the way, in such a device, the position of the plunger connecting the two rocker arms is located in the swinging part remote from the rocker shaft, so that not only the moment of inertia of the valve train system is increased. In addition, the friction increases due to the inertial force acting on the plunger, so that the plunger is hardly fitted into the fitting hole, and there is a problem that the switching response between the high-speed cam and the low-speed cam is deteriorated.

In addition, since a plurality of rocker arms are supported on a common rocker shaft for each cylinder, the number of components mounted on a single rocker shaft for a multi-cylinder engine increases, making disassembly and assembly work difficult. There was a problem that it became complicated.

An object of the present invention is to solve such a conventional problem.

(Means for Solving the Problems) The present invention includes a main rocker arm and a sub rocker arm which are slidably contacted with cams having different profiles. The main rocker arm has a distal end abutting on an intake valve or an exhaust valve and a proximal end thereof. A plunger, which is swingably supported on the cylinder head via a rocker shaft and locks the relative rotation of both rocker arms, extends between a fitting hole formed in the rocker shaft and a fitting hole formed in the sub rocker arm. Drive means for moving the plunger, and when the plunger moves and at least the main rocker arm and the sub rocker arm are locked, the plunger is moved to a position including the rocker shaft center axis. I did it.

(Operation) During low-speed operation, the main rocker arm is not restrained by the sub-rocker arm via the plunger, and the valve lifts according to the profile of the low-speed cam that slides on the main rocker arm. During high-speed operation, the main rocker arm swings integrally with the sub-rocker arm by the plunger fitted over both the fitting holes of the rocker shaft and the sub-rocker arm, and the profile of the high-speed cam that slides on the sub-rocker arm (low speed) The valve lifts as the valve opening angle or the valve lift becomes larger than that of the cam.

By arranging the plunger that locks the relative rotation of both rocker arms inside the rocker shaft in this way,
By reducing the moment of inertia of the valve operating system, it is possible to ensure valve followability during high-speed operation, and also to suppress the inertia force acting on the plunger to reduce friction during plunger movement, thereby improving the switching response of the cam. .

In addition, since the main rocker arm and the sub rocker arm are connected via a connecting shaft, they can be detached from the cylinder head as a unit, greatly improving the workability during engine assembly and disassembly. .

(Embodiment) FIGS. 1, 2 and 3 show two valves having the same function for one cylinder (either an intake valve or an exhaust valve, the illustrated one being an intake valve). 1 shows an embodiment in which the present invention is applied to an engine provided with the present invention.

To explain this, each cylinder has two intake valves 9.
A main rocker arm 1 is provided in a pair corresponding to the main rocker arm 1 and one sub rocker arm 2 is provided between the two main rocker arms 1.
Is provided. An intake valve 9 at the tip of the main rocker arm 1
The sub rocker arm 2 does not have a portion that comes into contact with the intake valve 9 while the stem top is brought into contact. An adjusting screw may be provided at the end of the main rocker arm 1 between the main rocker arm 1 and the intake valve 9 so that the valve clearance can be adjusted.

Rocker shafts 4 and 5 are press-fitted into bosses 7 provided between the cylinders of the cylinder head 8, and the main rocker arms 1 are swingably fitted to both ends of the rocker shafts 4 and 5, respectively. On the other hand, the sub rocker arm 2 is not directly fitted to the rocker shafts 4,5.

The base end of the sub rocker arm 2 is a connecting shaft
It is swingably connected to the main rocker arm 2 via the link 16. The connecting shaft 16 is slidably fitted in a fitting hole 17 formed in the sub rocker arm 2, while being pressed into a fitting hole 18 formed in each main rocker arm 1.

A roller 14 is rotatably connected to a shaft 13 via a needle bearing 12 in the middle of the main rocker arm 1, and a low speed cam is brought into rolling contact with the roller 14. In the figure, reference numeral 15 denotes a low-speed cam base circle.

A cam follower portion 19 slidably in contact with the high-speed cam is formed at the tip of the sub rocker arm 2 so as to protrude in an arc shape, and a lost motion spring 20 for pressing the cam follower portion 19 against the high-speed cam is provided below the cam follower portion 19 via a retainer 31. Abut In the figure, reference numeral 30 denotes a high-speed cam base circle.

As means for locking the relative rotation of the two rocker arms 1 and 2, a fitting hole 22 is formed in the sub rocker arm 2 for slidably fitting a plunger 21.
The fitting holes 25, which allow the plungers 23, 24 to slide
26 are formed concentrically.

As a driving means for moving the plungers 23, 21, and 24, an oil chamber 27 is defined behind the plunger 23, and a return spring 28 is interposed behind the plunger 24.

The respective fitting holes 22, 25, 26 are coaxially continuous at predetermined positions and are formed with the same diameter, and the plunger 23 is inserted into the fitting holes 25, 22 by operating hydraulic pressure guided to the oil chamber 27, and the plunger 21 is The main rocker arm 1 and the sub rocker arm 2 swing integrally by fitting over the fitting holes 22 and 26, respectively.

In a state in which the plunger 23 is in contact with the stopper 32 interposed in the fitting hole 25 due to the urging force of the return spring 28, the plungers 21, 23, 24 are accommodated in the fitting holes 22, 25, 26, respectively. The swing of each main rocker arm 1 is not restricted.

An air vent hole 29 (not shown) is connected to the fitting hole 26 into which the plunger 24 fits.

The boss 7 of the cylinder head 8 is provided with an oil passage 31 for guiding the operating oil pressure to the oil chamber 27, and the oil passage 31 is guided by a switching valve (not shown) at the time of a predetermined high-speed operation of the discharge oil pressure of the oil pump. The control unit that electronically controls the operation of the switching valve receives the engine rotation signal, cooling water temperature signal, lubricating oil temperature signal, supercharging pressure signal of the intake air by the supercharger, throttle valve opening signal, etc. Switching between a low-speed cam and a high-speed cam, which will be described later, is performed smoothly while suppressing a rapid change in engine torque based on the detected value.

The two low-speed cams and the high-speed cam located therebetween are integrally formed on a common camshaft, and have different shapes (sizes) so as to satisfy the valve lift characteristics required when the engine is running at a low speed and at a high speed. Are also included. That is, the high speed cam has a profile that makes at least one of the valve lift amount and the valve opening period larger than the low speed cam. here,
The valve lift and the valve opening period are both increased.

 Next, the operation will be described.

During low-speed operation of the engine, each main rocker arm 1 swings according to the profile of the low-speed cam, and opens and closes each intake valve 9. At this time, although the sub rocker arm 2 is swung by the high speed cam, the return spring 28
Each plunger 23,21,24 is caused by each of the mating holes 25,22,
26 fits each and does not hinder the movement of each main rocker arm 1.

On the other hand, when the operating oil pressure is guided to the oil chamber 27 through the oil passage 31 during high-speed operation of the engine,
1 and 24 move against the return spring 28, and the plunger 23 is fitted over the respective fitting holes 25 and 22, and the plunger 24 is fitted over the respective fitting holes 22 and 26. The three rocker arms 1 and 2 swing together. Here, since the high-speed cam is formed so that both the valve opening angle and the lift amount are larger than the low-speed cam, when the sub rocker arm 2 swings, the roller of each main rocker arm 1 is rotated. 14 rises from the low-speed cam, and each intake valve 9 is driven to open and close according to the profile of the high-speed cam, so that both the opening angle of the valve and the lift amount increase.

On the other hand, when the engine shifts from the high rotation range to the low rotation range again, the hydraulic pressure guided to the oil chamber 27 decreases by the operation of the switching valve, and the plungers 23, 21, and 24 return to the original state by the elastic restoring force of the return spring 28. The main rocker arm 1 is released from the position.

By mounting each plunger 2324 inside each rocker shaft 4, 5 and disposing it on the rocking center of rocker arms 1, 2, these plungers 23, 21, 24 increase the moment of inertia of the valve train. As a result, the valve followability is improved, which is advantageous for speeding up the engine.

In addition, the plungers 2324 are housed inside the rocker shafts 4 and 5 and arranged on the rocking centers of the rocker arms 1 and 2, so that the plungers 23 and 21 , 24, the plungers 23, 21, 24 do not increase the friction that occurs when moving in the axial direction, and provide smooth operability even during high-speed operation. Responsiveness can be improved.

Since the plungers 23 of the adjacent cylinders are housed inside the common rocker shaft 4, the oil chamber 27 and the oil passage 28 are shared between the two cylinders. Is peeled off.

The structure in which the sub rocker arm 2 is connected to the pair of main rocker arms 1 via the connecting shaft 16 makes it possible to attach and detach the valve operating device for transmitting the movement of the cam to the intake / exhaust valve from the cylinder head 8 as a unit. Become.

(Effects of the Invention) The present invention includes a main rocker arm and a sub rocker arm that are in sliding contact with cams having different profiles. A plunger that is swingably supported via a shaft and that can lock the relative rotation of both rocker arms can be moved across a fitting hole formed in the rocker shaft and a fitting hole formed in the sub rocker arm. The plunger is disposed at a position including the center axis of the rocker shaft when the plunger is moved and at least the main rocker arm and the sub rocker arm are in the locked state. , The increase of the moment of inertia of the rocker arm can be suppressed, The switching response of the cam can be enhanced by smoothing the operation of the locker, and the workability during disassembly and assembly of the engine can be improved by using a plurality of rocker arms provided for each cylinder as a unit.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a valve train showing an embodiment of the present invention, FIG. 2 is a transverse sectional view thereof, and FIG. 3 is a side sectional view taken along line AA of FIG. 1 ... Main rocker arm, 2 ... Sub rocker arm,
4,5 ... rocker shaft, 7 ... cylinder head boss, 1
6 ... connecting shaft, 21, 23, 24 ... plunger, 22, 25, 26 ... fitting hole, 27 ... oil chamber, 28 ... oil passage.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-19104 (JP, A) JP-A-3-47416 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01L 13/00 301 F01L 13/00 302

Claims (1)

(57) [Claims] A main rocker arm and a sub rocker arm are provided for slidingly contacting cams having different profiles from each other. The main rocker arm has a distal end abutting on an intake valve or an exhaust valve, and has a base end connected to a cylinder head via a rocker shaft. A plunger that is swingably supported and capable of locking the relative rotation of both rocker arms is movably housed over a fitting hole formed in the rocker shaft and a fitting hole formed in the sub rocker arm, Driving means for moving the plunger is provided, and the plunger is located at a position including the center axis of the rocker shaft when the plunger moves and at least the main rocker arm and the sub rocker arm are locked. Engine valve actuating device.