JPH0618004Y2 - Valve forced opening / closing device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a valve forced opening / closing device for forcibly opening / closing an intake valve or an exhaust valve of an internal combustion engine.

(Prior Art) A valve opening cam and a valve closing cam are formed on a rotating camshaft in order to improve the followability of the intake and exhaust valves at high speed.
A desmodromic valve opening / closing device is known in which intake and exhaust valves are forcibly opened and closed by these cams without the aid of a valve spring.

FIG. 4 shows an example of a valve opening / closing device of this type. The rocker arms 5, 6 are attached to the rocker shaft 4 in correspondence with the valve opening cam 2 and the valve closing cam 3 formed on the camshaft 1.
Is pivotally supported, and the tip end of the valve opening rocker arm 5 that is in sliding contact with the valve opening cam 2 via the adjusting screw 7 from above to the valve shaft end 9 of the intake valve (or exhaust valve) 8 and the valve closing cam 3
The tip end of the valve-closing rocker arm 6 slidingly contacting with is abutted from below onto the retainer 11 fixed to the valve shaft 10.

Therefore, when the cam shaft 1 rotates, the tip ends of the rocker arms 5 and 6 follow the valve opening cam 2 and the valve closing cam 3 first, and are pushed down by the valve opening rocker arm 5 to move the intake valve 8. When the rocker arms 5 and 6 are opened, the tips of the rocker arms 5 and 6 are moved upward and pulled by the valve-closing rocker arm 6 to close the intake valve 8.

Further, FIG. 5 shows an intake valve (or an exhaust valve) 16 via a retainer 15 having upper and lower flanges, in which a first rocker arm 13 slidably contacting a valve opening cam 12 is screwed to a valve shaft 14. The second rocker arm 18 that is in contact with the valve closing cam 17 is engaged with the first rocker arm 1
3 is abutted in the valve closing direction.

Therefore, when the cam shaft 19 rotates, the first rocker arm 13 moves downward following the valve opening cam 12, the intake valve 16 is opened first, and then the second closing cam 17 is followed. The first rocker arm 13 is moved upward by the rocker arm 18 to close the intake valve 8 (Japanese Utility Model Laid-Open No. 61-6611, JP-A-60-3291).
0, 32911, Jpn. Pat. Appln. KOKAI No. 53-51928, etc.).

(Problems to be solved by the invention) However, in the case of FIG. 4, the clearance between the valve closing rocker arm 6 and the retainer 11 fixed to the valve shaft 10 (valve closing side clearance) cannot be adjusted. If the valve closing rocker arm 6, the retainer 11, etc. have variations in size or wear, the clearance with the retainer 11 increases, noise and vibration occur, and the valve 8 does not completely adhere to the valve seat. is there.

Further, in the one shown in FIG. 5, the first rocker arm 13 is engaged with the valve shaft 14 via the retainer 15 having upper and lower flanges. In this case, the retainer 15 is screwed to connect the lower flange and the rocker arm 13. Even if the clearance (valve-opening side clearance) can be adjusted, if the retainer 15 and the rocker arm 13 have dimensional variations and wear, the clearance with the upper flange (valve-closing side clearance) is unavoidably increased. There is a problem that the valve 16 does not come into close contact with the valve seat as well as noise and vibration are generated.

An object of the present invention is to provide a valve forced opening / closing device that solves such problems.

(Means for Solving the Problem) The present invention relates to a valve forced opening / closing device for an internal combustion engine in which a cam opening and closing valve for opening and closing an intake valve and an exhaust valve is formed on a cam shaft. A valve-opening rocker arm that follows the valve cam and a valve-closing rocker arm that follows the valve-closing cam are arranged in a cross shape, while a lock nut and a valve-opening follower are provided in the middle of the valve shafts of the intake and exhaust valves. Attach the nut to the valve closing follower nut and the lock nut in order on the upper part, and engage the valve opening rocker arm on the upper surface of the valve opening follower nut and the valve closing rocker arm on the lower surface of the valve closing follower nut. To combine.

(Function) Therefore, each follower nut allows adjustment of the clearance on the valve opening side and the valve closing side, and since each follower nut and lock nut are located outside them with the rocker arms in between, the clearance adjustment is performed. Will be easier.

(Embodiment) FIGS. 1 and 2 show an embodiment of the present invention, in which 30 is a cam shaft which is rotationally driven by an engine, 31 is an intake valve or an exhaust valve (hereinafter referred to as valve), and 32 is a cam. The rocker shaft is arranged between the shaft 30 and the valve 31 in parallel with the cam shaft 30.

The camshaft 30 has a valve opening cam 33 and a valve closing cam 34.
Are formed substantially adjacent to each other, and correspondingly, the rocker shaft 32 has a valve-opening rocker arm 35 whose one end is in sliding contact with the valve-opening cam 33 from above, and a closed valve whose one end is in sliding contact with the valve-closing cam 34 from below. A valve rocker arm 36 is provided.

The cam 33 for opening the valve has a high portion 33a at one position in the circumferential direction.
The valve closing cam 34 is formed in a profile having a lower portion 34a at one position in the circumferential direction, and the relative positions of these are set by the opening / closing cycle of the valve 31 and the sliding contact position of the rocker arms 35, 36.

The valve opening rocker arm 35 and the valve closing rocker arm 36 are
The rocker shaft 32 is pivotally supported by the rocker shaft 32 via the boss portions 35a, 36a, and in this case, both rocker arms 35, 36 are arranged so as to cross when viewed from the shaft 32 direction.

The rocker shaft 32 is supported on the outside of the boss portions 35a and 36a, and the shaft 3 of the rocker arms 35 and 36 is supported.
Brackets 37 and 38 are arranged to prevent displacement in two directions.

On the other hand, the valve 31 is slidably supported in the valve shaft direction via a valve guide (not shown), and the valve shaft 40
A threaded portion 41 is formed from the upper part to the intermediate portion of the valve, and a lock nut 42 and a valve-opening follower nut 43 in which a female thread is formed inside the threaded portion 41 of the intermediate portion are
Similarly, a valve-closing follower nut 44 and a lock nut 45, each having a female thread inside, are screwed in order with the upper surface 43a of the follower nut 43 and the lower surface 44a of the follower nut 44 facing each other.

Then, the tip end portion 35b of the valve opening rocker arm 35 is brought into contact with the upper surface 43a of the valve opening follower nut 43 from above, and the lower surface 44a of the valve closing follower nut 44 is arranged so as to cross the valve opening rocker arm 35. The tip portion 36b of the valve closing rocker arm 36 is brought into contact with the lower portion from below.

In this case, the tip end portions 35b and 36b of the valve opening rocker arm 35 and the valve closing rocker arm 36 are formed so as to sandwich the valve shaft 40, and are provided on one side of the upper surface 43a and the lower surface 44a of the corresponding follower nuts 43 and 44, respectively. The follower nuts 43 and 44 are formed so as to come into contact with each other in the tightening direction when the valve 31 is operated.

In order to apply a predetermined valve closing force when the valve 31 is closed (a low engine speed range where the valve closing force is weak, etc.), the boss portion 36a of the valve closing rocker arm 36 is provided with a tip end portion 36b with the bracket 38. A torsion spring 46 that biases upward is interposed.

With such a configuration, when the valve 31 is opened, the tip end portions 35b and 36b of the valve opening rocker arm 35 and the valve closing rocker arm 36 follow the valve opening cam 33 and the valve closing cam 34.
Moves downward, and the tip portion 35b of the valve opening rocker arm 35 pushes the valve opening follower nut 43 of the valve shaft 40 to open the valve 31, while the valve opening cam 33, when the valve 31 is closed, Following the valve closing cam 34, the tip end portion 35 of the valve opening rocker arm 35 and the valve closing rocker arm 36.
b and 36b move upward, and the tip end portion 36 of the valve closing rocker arm 36
The valve 31 is closed by pulling the valve closing follower nut 44 of the valve shaft 40 by b.

The clearance between the tip end portion 35b of the valve opening rocker arm 35 and the valve opening follower nut 43 is determined by loosening the lock nut 42, aligning the follower nut 43 to a predetermined position, and fixing the follower nut 43 with the lock nut 42 again. The clearance between the tip end portion 36b of the valve closing rocker arm 36 and the valve closing follower nut 44 can be adjusted similarly by loosening the lock nut 45.
It can be adjusted by aligning 4 with a predetermined position and fixing the follower nut 44 with the lock nut 45 again.

Therefore, even if the rocker arms 35 and 36, the follower nuts 43 and 44, the valve 31, and the like have variations in size and wear, the clearances can be adjusted to appropriate values in accordance with these, and noise and vibration are not generated during opening and closing. In addition to the prevention, incomplete contact of the valve 31 with the valve seat can be prevented when the valve 31 is closed, and a good operation of the valve 31 can always be ensured.

Also, the rocker arm 35 for opening the valve and the rocker arm 3 for closing the valve
6 are arranged crosswise, and the rocker arm 3 for opening the valve
5 is engaged with the upper surface 43a of the follower nut 43, and the valve closing rocker arm 36 is engaged with the lower surface 44a of the follower nut 44.
Since it is located outside b and 36b, the clearance can be easily adjusted using a tool or the like, and good maintainability can be obtained.

FIG. 3 shows another embodiment of the present invention, in which the valve opening rocker arm 47 and the valve closing rocker arm 48 are supported by separate camshafts 49 and 50, and the rocker arm 4 is provided.
The shafts 7 and 48 are curved. Further, female threads are not formed on the follower nuts 51 and 52, and instead, two lock nuts 53 and 54 are provided.

According to this, the rocker arms 47 and 48 and the cams 33 and 3
The sliding contact position of 4 can be set arbitrarily, and the follower nut 5
Screw processing of 1,52 is unnecessary.

(Effect of the Invention) As described above, according to the present invention, in the valve forced opening / closing device of the internal combustion engine, which has the cam for opening and closing the cam for sucking and exhausting the camshaft and the valve for closing the cam. , A valve-opening rocker arm that follows the valve-opening cam and a valve-closing rocker arm that follows the valve-closing cam are arranged in a cross shape,
A lock nut and a valve-opening follower nut are screwed in the middle of the valve shafts of the intake and exhaust valves, and a valve-closing follower nut and a lock nut are screwed in that order on the upper part. Since the rocker arms for closing the valve are engaged with the lower surface of the follower nut for closing the valve, the clearances on the valve opening side and the valve closing side can be adjusted to appropriate values even if the rocker arms have variations in size or wear. In addition, the adjustment can be easily performed, the generation of noise and vibration can be prevented, and good operation can always be obtained.

[Brief description of drawings]

1 and 2 are a side view and a plan view showing an embodiment of the present invention, FIG. 3 is a side view of another embodiment of the present invention, and FIGS. 4 and 5 are side views of a conventional example. is there. 30 ... Cam shaft, 31 ... Valve, 33 ... Valve opening cam, 34 ... Valve closing cam, 35 ... Valve opening rocker arm, 3
6 ... Valve closing rocker arm, 40 ... Valve shaft, 42, 45 ... Lock nut, 43 ... Valve opening follower nut, 44 ... Valve closing follower nut.

Claims (1)

[Scope of utility model registration request] 1. A valve opening and closing device for an internal combustion engine, comprising a valve opening cam for opening and closing an intake valve and an exhaust valve on a cam shaft, and a valve closing cam for closing the valve. The locker arm for the valve and the rocker arm for closing the valve that follows the valve closing cam are arranged in a cross shape, while the lock nut and the follower nut for opening the valve are located in the middle of the valve shafts of the intake and exhaust valves, and the valve is closed at the top. A follower nut and a lock nut are screwed in order, and the valve opening rocker arm is engaged with the upper surface of the valve opening follower nut, and the valve closing rocker arm is engaged with the lower surface of the valve closing follower nut. Forced opening and closing device for internal combustion engine.