JP3157365B2 - Cam chain tensioner device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam chain tensioner device for an overhead valve cam type four-stroke internal combustion engine, and more particularly to a mounting portion of a tensioner body.

[0002]

2. Description of the Related Art In a four-stroke internal combustion engine, a cam is used to remove the slack of an endless chain that is bridged between a cam sprocket integral with a valve cam and a sprocket integral with a crankshaft to give proper tension. A chain tensioner device was provided.

The load applied to the valve operating cam changes periodically in accordance with the timing of opening and closing the intake and exhaust valves, and the tension of the cam chain fluctuates.
As shown in Japanese Patent Publication No. 32, an elastic body is disposed below a pin pivotally supporting the lower end of the tensioner main body, so as to absorb vibration applied to the tensioner main body due to fluctuation in the tension of the cam chain.

[0004]

In the conventional cam chain tensioner device, vibration force along the longitudinal direction of the tensioner body can be absorbed, but vibration along the width direction of the cam chain cannot be absorbed.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an improvement in a cam chain tensioner device for an internal combustion engine which overcomes such difficulties, and is provided in a crankcase of the internal combustion engine at right angles to a chain housing. In a cam chain tensioner device for mounting and supporting a mounting base extending in a width direction of a tensioner provided at a base end of a tensioner main body in a mounting concave portion, an elastic member integrally formed with the tensioner main body may be used for the mounting base. An extension base extending in the width direction of the tensioner is formed along the tensioner, and the elastic member is disposed so that the tensioner width direction extension base of the elastic member can abut on an inner wall surface of the chain storage portion in the tensioner width direction. It is characterized by having been provided.

According to the present invention, the elastic member is formed integrally with the tensioner main body when a vibration force or an impact force is applied to the tensioner main body in the width direction. Forming an extension base extending in the width direction of the tensioner along the mounting base, so that the tensioner width direction extension base of the elastic member can abut on the tensioner width direction inner wall surface of the chain storage portion. Since the elastic member is provided, the vibration force and the impact force in the width direction are buffered and absorbed by the base of the elastic member extending in the tensioner width direction.

As described above, according to the present invention, a multi-joint cam chain which is liable to roll in response to pulsation of an internal combustion engine by elastic control in the width direction while preventing an increase in the weight of the entire cam chain tensioner. The width direction force can be more effectively attenuated, and the valve operating mechanism can be operated quietly and appropriately.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 6 will be described below. In an overhead valve cam type two-cylinder four-cycle internal combustion engine 1 mounted on a motorcycle (not shown), a lower crankcase 2 divided vertically and an engine block 3 serving also as an upper crankcase and a cylinder block are provided. A crankshaft 7 is rotatably supported via a slide bearing 6, and a cylinder head 4 and a head cover 5 are stacked above the cylinder block 3 and integrally connected to each other.

The crankshaft 7 is connected via a connecting rod 10 to a piston 9 fitted reciprocally up and down in the cylinder 8 of the cylinder block 3.
The crankshaft 7 is driven to rotate in accordance with the elevation of the piston 9.

Further, an intake valve is provided on the cylinder head 4.
11 and an exhaust valve (not shown) are provided, and a valve cam 12 is disposed above the extension of the intake valve 11 and the exhaust valve. It is held rotatably.

Further, a sprocket 14 is integrally formed at a central portion of the crankshaft 7 and a cam sprocket 15 having twice the number of teeth of the sprocket 14 is integrally fitted at a central portion of the camshaft 13 to thereby form a sprocket. 14
An endless chain 16 is bridged between the cam sprocket 15 and the cam sprocket 15. When the crankshaft 7 rotates twice, the cam sprocket 15 and the valve gear cam 12 are driven one rotation.

In addition, a cam chain storage chamber 17 is formed between the left and right cylinders 8 in the cylinder block 3 and the cylinder head 4, and the cam chain storage chamber 17 is provided on the vehicle body front side (exhaust port side). A chain guide 18 is provided, a cam chain tensioner device 20 is provided behind the cam chain storage chamber 17 on the vehicle body side (intake port side), and a chain guide 19 is provided above the cam sprocket 15. ing.

In the cam chain tensioner device 20,
Attachment base 24 of tensioner body 23 formed by integrally baking rubber cushioning material 22 on the surface and base of steel strip member 21
On the other hand, a steel pin 25 is integrally fitted, a Teflon resin guide 26 is integrally laminated on the chain contact surface of the cushioning material 22, and the upper half 26a of the guide 26 is formed in a groove shape. Is formed.

Further, a lifter 28 is disposed at a position slightly above the center of the tensioner main body 23 and at the rear thereof, and a tip of a rod 29 of the lifter 28 has a width substantially equal to the diameter of the rod 29. Is fitted into the concave portion 27 of
The lifter 28 pushes the tensioner main body 23 forward to give the endless chain 16 a substantially constant tension state irrespective of the swing of the tensioner main body 23 by a spring, hydraulic pressure or the like.

Furthermore, a pin integrated with the tensioner body 23
25 is fitted in the concave portion 30 of the cylinder block 3 and is sandwiched between the concave portion 30 and the crankcase 2. The base 22 a of the cushioning material 22 in the mounting base 24 of the tensioner main body 23 is located inside the left and right sides of the cam chain storage chamber 17. It is sandwiched between wall surfaces 17a.

Since the embodiment shown in FIGS. 1 to 6 is configured as described above, when the four-stroke internal combustion engine 1 starts operating, the rotation of the crankshaft 7 causes the sprocket 14, the endless chain 16, The valve cam 12 is transmitted in a reduced speed by half through the cam sprocket 15 and the camshaft 13, and the slippers 31 at the top ends of the intake valve 11 and the exhaust valve are pushed downward in accordance with the elevation of the piston 9,
The intake valve 11 and the exhaust valve are opened intermittently.

When the intake valve 11 and the exhaust valve are opened, the load applied to the camshaft 13 periodically increases. As a result, the tension of the endless chain 16 increases, and the tension of the endless chain 16 is about to change. Well, lifter 28
As a result, the tensioner body 23 is pushed forward, and the endless chain 16 is prevented from swinging back and forth.

Further, in this case, even if a force in the width direction is generated in the endless chain 16, the endless chain 16 is fitted into the groove 26a of the guide portion 26 of the tensioner main body 23, and furthermore, is fitted into the recess 27 of the tensioner main body 23. The tip of the rod 29 of the lifter 28 is fitted, and the base 22a of the cushioning material 22 in the mounting base 24 of the tensioner main body 23 is sandwiched between the left and right inner wall surfaces 17a of the cam chain storage chamber 17 to move the tensioner main body 23 in the width direction. Is elastically restricted, so that the lateral runout of the endless chain 16 is reliably suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view illustrating an embodiment of a cam chain tensioner device in an internal combustion engine according to the present invention.

FIG. 2 is a vertical sectional view taken along the line II-II in FIG.

FIG. 3 is a view taken in the direction of arrows III-III in FIG.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

FIG. 5 is a transverse sectional view cut along the line VV of FIG. 3;

FIG. 6 is a view taken in the direction of arrows VI-VI in FIG. 1;

[Explanation of symbols]

1 ... 4 cycle internal combustion engine, 2 ... lower crankcase, 3 ...
Cylinder block, 4 ... Cylinder head, 5 ... Head cover, 6 ... Sliding bearing, 7 ... Crank shaft, 8 ... Cylinder, 9 ... Piston, 10 ... Connecting rod, 11 ...
Intake valve, 12: Valve cam, 13: Cam shaft, 14: Sprocket, 15: Cam sprocket, 16: Endless chain, 17: Cam chain storage room, 18, 19: Chain guide, 20: Cam chain tensioner device, 21 ... Strip-like members,
22 ... cushioning material, 23 ... tensioner body, 24 ... mounting base, 25
... pins, 26 ... guides, 27 ... recesses, 28 ... lifters, 29 ...
Rod, 30 ... recess, 31 ... slipper, 32 ... cam holder.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Imai 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References JP-A-4-272548 (JP, A) Sho Akai Kai 56-47232 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H ^7/ 00-7/24 F02B 67/06

Claims (1)

(57) [Claims] A cam chain for mounting and supporting a mounting base extending in a width direction of a tensioner provided at a base end of a tensioner main body in a mounting recess provided in a crankcase of an internal combustion engine at right angles to a chain housing. In the tensioner device, an elastic member integrally formed with the tensioner main body extends in a width direction of the tensioner along the mounting base.
Forming an extended base portion extending from the chain storage portion;
The elastic member extends in the tensioner width direction on the inner wall in the width direction
A cam chain tensioner device for an internal combustion engine , wherein the elastic member is disposed so that a base portion can abut .