JPH0730888Y2 - 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.
There is known a desmodromic valve opening / closing device in which intake and exhaust valves are forcibly opened and closed by these cams without the help of a valve screw.

FIG. 5 shows an example of this type of valve opening / closing device, in which rocker arms 5 and 6 are pivotally mounted on a rocker shaft 4 corresponding to a cam 2 for opening a valve and a cam 3 for closing a valve formed on a camshaft 1. The tip of the valve-opening rocker arm 5 which is supported and slides on the valve-opening cam 2 slides on the valve-closing cam 3 from above through the adjustment screw 7 to the valve shaft end 9 of the intake valve (or exhaust valve) 8. The tip end of the valve closing rocker arm 6 is brought into contact with the retainer 11 fixed to the valve shaft 10 from below.

Therefore, when the camshaft 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 push the intake valve 8
When the rocker arms 5 and 6 are opened, the tip ends of the rocker arms 5 and 6 are moved upward and are pulled by the valve closing rocker arm 6 to close the intake valve 8.

Further, as shown in FIG. 5, an intake valve (or an exhaust valve) is provided through a retainer 15 having first and second flanges on which a first rocker arm 13 slidingly contacting a valve opening cam 12 is screwed to a valve shaft 14 and having upper and lower flanges.
The second rocker arm 18 that engages with the valve closing cam 17 is brought into contact with the first rocker arm 13 in the valve closing direction.

Therefore, when the cam shaft 19 rotates, the valve opening cam
The first rocker arm 13 moves downward following 12 and the intake valve 16 is opened first, and then the second rocker arm 18 following the valve closing cam 17 moves the first rocker arm 13 upward. The intake valve 8 can be closed.
-6611, JP-A-60-32910, 32911, JP-B-53-5192
(See Publication No. 8).

(Problems to be Solved by the Invention) By the way, in an internal combustion engine having two intake valves and two exhaust valves for each cylinder of the engine, in order to simplify the structure, for example, two Y-shaped rocker arms are used. Although the intake valve or the exhaust valve is driven at the same time, when applied to such an internal combustion engine, in the case of FIG. 5, the clearance between the valve closing rocker arm 6 and the retainer 11 fixed to the valve shaft 10 ( Since the clearance on the valve closing side cannot be adjusted, even if the rocker arm 6 is formed in a Y shape, for example, if the rocker arm 6 or the retainer 11 has a dimensional variation, the clearance will be different. There is a problem that noise or abnormal noise is generated and one of the valves does not completely adhere to the valve seat.

Further, in FIG. 6, two valves are opened and closed by using a Y-shaped one for the first rocker arm 13, and the first rocker arm 13 is provided with a retainer 15 having upper and lower flanges respectively. However, in this case, even if the clearance between the lower flange and the rocker arm 13 (valve opening side clearance) can be adjusted by the retainer 15, there are variations in the dimensions of the rocker arm 13 and the retainer 15. Inevitably, the clearance between the upper flange and the rocker arm 13 (valve closing side clearance) is unavoidably increased, and there is a difference in clearance between the retainers 15. There is a problem that it does not adhere to the sheet.

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

(Means for Solving the Problem) According to the present invention, a Y-shaped valve-opening rocker arm that follows the valve-opening cam formed on the camshaft and a valve-closing cam that also forms on the camshaft are followed. A valve forced opening / closing device for an internal combustion engine, comprising a Y-shaped valve closing rocker arm, and forcibly opening / closing two intake valves or two exhaust valves arranged for each cylinder through these rocker arms. A clearance adjustment in which the valve-opening rocker arm is brought into contact with the shaft end of an intake valve or an exhaust valve via an adjustment screw for clearance adjustment provided at the tip end thereof, and is inserted into the valve shaft of the intake valve or the exhaust valve. Similarly, the upper surface of the adjusting collar for use is brought into contact with a nut screwed to the valve shaft so that the position of the adjusting collar can be adjusted, and the valve closing rocker arm is brought into contact with the lower surface of the adjusting collar.

(Operation) Therefore, the clearance between the Y-shaped valve opening rocker arm and valve closing rocker arm and the intake and exhaust valves can be adjusted independently and properly, and the variations in the dimensions of the rocker arm, intake and exhaust valves are compensated. As a result, it is possible to reliably prevent the generation of hammering noise and abnormal noise when the valve is opened and closed.

(Embodiment) FIGS. 1 and 2 show an embodiment of the present invention, in which 30 is a camshaft rotationally driven by an engine, 31 is an intake valve or an exhaust valve (two for each cylinder of the engine). Hereinafter, referred to as valves) 32 and 33 are rocker shafts arranged between the cam shaft 30 and the valve 31 in parallel with the cam shaft 30.

A valve opening cam 34 and a valve closing cam 35 are formed on the cam shaft 30 so as to be adjacent to each other. Correspondingly, the rocker shaft 32 has a Y-shaped one end of which is in sliding contact with the valve opening cam 34 from above. The rocker arm 36 for valve opening and the cam for valve closing on the rocker shaft 33.
A Y-shaped valve-closing rocker arm 37, one end of which is slidably contacted from below, is arranged at 35.

The valve-opening cam 34 is formed in a profile having a high position 34a at one position in the circumferential direction and the valve-closing cam 35 is formed in a profile having a low position 35a at one position in the circumferential direction. It is set by the cycle and the sliding contact position of the rocker arms 36, 37.

The valve opening rocker arm 36 and the valve closing rocker arm 37 are swingably supported by the rocker shafts 32 and 33 via the boss portions 36a and 37a, and the rocker shafts 32 and 33 are arranged on both sides of the boss portions 36a and 37a. Supported by brackets 38 and 39,
Between them is a shim 4 that positions the rocker arms 36, 37.
0,41 are installed.

On the other hand, the two valves 31 are slidably supported in the valve axis direction via valve guides (not shown), and a threaded portion 43 is formed on each valve shaft 42. Lock nut with internal thread
44a and 44b are screwed. Only one valve 31 is shown.

Then, corresponding tip portions 46a and 46b of the Y-shaped valve-opening rocker arm 36 are applied to the valve shaft ends 45 of both valves 31 from above via respective adjusting screws 47 attached to the tip portions 46a and 46b. While being contacted, the lock nuts 44a, 44
A cylindrical adjust collar 48 as shown in FIG. 3 is fitted to the valve shafts 42 of both valves 31 at the lower part of b, and the Y-shaped rocker arms for closing the valve are attached to the lower surface of each adjust collar 48.
Corresponding tip portions 49a, 49b of 37 are abutted from below.

The adjust screw 47 is screwed into the tip end portions 46a and 46b of the valve opening rocker arm 36, and after adjusting the clearance with the valve shaft end 45, is fixed by the lock nuts 50a and 50b.

The adjust collar 48 is held by the lock nuts 44a, 44b and the tip portions 49a, 49b of the valve closing side rocker arm 37, and the tip portions 49a, 44b are moved back and forth to move the tip portions 49 of the lock collars 44a, 44b.
The clearance with a and 49b is adjusted.

The tip ends 49a, 49b of the valve closing rocker arm 37 are formed so as to contact the adjusting collar 48 with the valve shaft 42 sandwiched therebetween, as shown in FIG.

With this configuration, when the valve 31 is open, the valve opening cam
34, the respective tip portions 46a, 46b, 49a, 49b of the valve opening rocker arm 36 and the valve closing rocker arm 37 follow the valve closing cam 35, and the respective tip portions 46a, 46b of the valve opening rocker arm 36 are lowered. While both valves 31 are opened via the adjustment screw 47 of
When the valve 31 is closed, the valve opening cam 34 and valve closing cam 35 are also used.
Following the above, the rocker arm for valve opening 36 and the rocker arm for valve closing
The respective tip portions 46a, 46b, 49a, 49b of 37 are moved upward, and both valves 31 are closed via the adjusting collar 48 that abuts on the tip portions 49a, 49b of the valve closing rocker arm 37.

Then, each clearance between the tip end portions 46a, 46b of the valve opening rocker arm 36 and the valve shaft end 45 of both valves 31 can be adjusted by an adjusting screw 47, and the tip end portions 49a, 49b of the valve closing rocker arm 37 can be adjusted. Adjust color 48
The clearances between the lock nuts 44a and 44b are
Can be adjusted by moving the adjust color 48 back and forth.

Therefore, even if the rocker arms 36, 37, both valves 31, the adjustment collar 48, and the like have variations in size, each clearance can be set to an appropriate value, and by using the Y-shaped rocker arms 36, 37, the valve opening side or There is no difference in clearance on the valve closing side, and as a result, it is possible to prevent tapping and abnormal noise when the valve 31 is opened and closed, and to prevent incomplete adhesion of the valve 31 to the valve seat when closed. 31
The good operation of can be secured.

As described above, according to the present invention, a Y-shaped valve-opening rocker arm that follows the valve-opening cam formed on the cam shaft,
Similarly, Y that follows the valve closing cam formed on the camshaft.
In a valve forced opening / closing device of an internal combustion engine, which is provided with a V-shaped valve closing rocker arm, and forcibly opens / closes two intake valves or two exhaust valves arranged for each cylinder via these rocker arms, The valve opening rocker arm is brought into contact with the shaft end of the intake valve or the exhaust valve via a clearance adjusting screw provided at the tip end thereof, and the clearance is inserted into the valve shaft of the intake valve or the exhaust valve. Since the upper surface of the adjusting collar is brought into contact with a nut screwed to the valve shaft so that the position can be adjusted, and the valve closing rocker arm is brought into contact with the lower surface of the adjusting collar, a valve opening rocker arm and a valve closing rocker arm are formed. Suck,
The clearance with the exhaust valve can be adjusted independently and properly, compensating for variations in the dimensions of the rocker arm, suction and exhaust valves, and ensuring the generation of hammering noise and abnormal noise when opening and closing the valve. It can be prevented.

[Brief description of drawings]

1 and 2 are side views and plan views showing an embodiment of the present invention, FIGS. 3 and 4 are partial plan views and partial sectional views thereof, and FIGS. 5 and 6 are side views of a conventional example. It is a figure. 30 ... Cam shaft, 31 ... Valve, 34 ... Valve opening cam, 35 ...
Cam for closing valve, 36 ... Rocker arm for opening valve, 37 ... Rocker arm for closing valve, 42 ... Valve shaft, 45 ... Valve shaft end, 47 ... Adjusting screw, 48 ... Adjusting collar.

Front Page Continuation (72) Inventor, Kugo Hamai, 2 Takara-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. (56) References JP 61-275511 (JP, A) JP 60-119308 (JP) , A)

Claims (1)

[Scope of utility model registration request] 1. A Y-shaped valve-opening rocker arm that follows a valve-opening cam formed on a camshaft, and a Y-shaped valve-closing rocker arm that follows a valve-closing cam that is also formed on a camshaft. In the valve forced opening / closing device of an internal combustion engine, which is configured to forcibly open / close two intake valves or two exhaust valves arranged for each cylinder via these rocker arms, The clearance adjustment screw, which is provided at the tip of the intake valve or exhaust valve, is brought into contact with the shaft end of the intake valve or exhaust valve via the clearance adjustment screw, and the upper surface of the clearance adjustment collar is inserted into the valve shaft of the intake valve or exhaust valve. A valve forcing valve for an internal combustion engine, characterized in that it is brought into contact with a nut that is screwed onto the valve shaft so that its position can be adjusted, and the rocker arm for closing the valve is brought into contact with the lower surface of the adjusting collar. Closing device.