JPH0128247Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement of a rotation prevention device for a roller tappet of an internal combustion engine, and in particular, to automatically adjust the ideal positional relationship in contact between the roller tappet and a cam. This invention relates to a rotation prevention device for a roller tappet.

[Technical background of the invention and its problems] Figure 1 shows the structure of a valve train in a general internal combustion engine. To briefly explain this, the intake (exhaust) valve 1 has the following structure: Opening/closing operations are performed by a bridge arm 4 that operates in response to the swinging of a rocker arm 3 supported on a rocker shaft 2. The swinging motion of the rocker arm 3 is controlled via a push rod 5 and a tappet 6 by a crankshaft (not shown). This is provided by a cam 8 formed on a camshaft 7 driven by a camshaft 7. In order to improve durability by making the contact between the cam 8 and the tappet 6 a rolling contact, the roller 9 is moved to the tappet 6 on the axis in the lifting direction as shown in the figure.
It is located at the bottom of the .

By the way, when the roller 9 engages with the bulged portion of the cam 8 during the lift stroke, it comes into contact at a position spaced apart from the axis in the lift direction and is pushed up. At this time, the rotational direction (tangential line) of the roller 9 is made to coincide with the profile direction of the cam 8 due to a known action in a cast or the like. In other words, the engagement is at the normal position.

On the other hand, when the roller 9 engages with the arc-shaped portion of the cam 8 during the non-lift stroke, only the rolling force is transmitted at the contact point on the axis, so the arrow A in FIG. Such a turn will be permitted.

However, if the deviation from the normal position increases due to this turning, the roller 9 will no longer be able to roll on the cam 8. Therefore, in order to maintain a constant positional relationship in contact with the profile of the cam 8, the roller 9 will rotate around the tappet 6. It becomes necessary to apply a stop. This rotation stopper needs to have a certain degree of freedom in the turning direction (centered on the vertical movement of the tappet 6) for accuracy or assembly reasons.

Therefore, in the conventional roller tappet 6,
The contact portion 11a at the tip of the stopper 11 attached to the body 10 is inserted into a large groove 12 provided in the tappet, and the locking action of these prevents the tappet 6 from turning as indicated by the arrow A. Ta.

However, since the width of the groove 12 provided in the tappet 6 to provide freedom in preventing rotation is large, when the tappet 6 begins to rise during the lift stroke,
A force that attempts to bring the roller 9 and cam 8 into contact with each other, which have been misaligned within the range of degrees of freedom, to the correct position is suddenly applied as a force that rotates the tappet 6 around its axis. This force is directly transmitted to the abutting portion 11a and the groove 12, and as the abutting action is repeated, the abrasion of the locking portion becomes extremely significant. There are also disadvantages in that defects occur, and it is also troublesome to match the tappet 6 and stopcock 11 when assembling the engine.

Incidentally, as a related technique, a ``device for preventing tapepet rotation of an internal combustion engine'' (Japanese Utility Model Application Publication No. 101402/1982) has been proposed.

[Purpose of the invention] The present invention was made in view of the above-mentioned drawbacks, and its purpose is to automatically adjust the ideal positional relationship in contact between the roller tappet and the cam, and to eliminate wobbling when turning. To provide a roller tappet equipped with a rotation stopper for an internal combustion engine, which is highly reliable, easy to assemble, suitable for mass production, and has a simple structure.

[Summary of the invention] According to the invention, the above object is achieved as follows.

That is, the present invention provides a roller provided at the tip of the tappet and a cam that engages with the roller on the axis in the lifting direction, and a vertically long tappet that is loosely fitted into a stopper protruding from the cylinder body. A ring-shaped retainer having a vertical slit narrower than the vertical groove is crimped onto the inner circumferential wall of the tapepet so that a stopper is inserted into the vertical slit, and a non-lift It is constructed by imparting elasticity to brake the rotational movement of the tappet around its axis that is allowed during the stroke by the frictional force generated between the tappet and the inner circumferential wall.

With the above configuration, when the tappet attempts to pivot within the width of the longitudinal groove during a non-lift stroke, the retainer generates a frictional force with the inner circumferential wall to suppress the pivoting movement. . Then, when moving to the lift stroke, the sudden turn is made by an amount corresponding to the deviation from the normal position that was occurring at that time, but this amount is gradually attenuated by the braking of the retainer, and it is essentially returned to the normal position. is automatically adjusted.

[Embodiment of the invention] Hereinafter, a preferred embodiment of the rotation stopper according to the invention will be described with reference to the accompanying drawings.

As shown in FIGS. 2 to 4, a tappet 17 that is slidably engaged with a hole 16 of a cylinder body 15 is provided with a longitudinal groove 19 facing both sides of a roller 18 provided at its lower end. . This vertical groove 1
9 is wider than the stopper 20 to allow a certain degree of freedom in assembling the stopper 20, which will be described later, and is long enough to allow vertical movement of the tappet 17 when the stopper 20 is inserted. It is formed to have.

Reference numeral 21 denotes a ring-shaped retainer made of a member with a predetermined elasticity that is partially cut out, and has a vertical slit that engages with the stopper 20 at an appropriate position and allows the stopper 20 to slide only in the vertical direction. 22 are provided.
Since this vertical slit 22 only allows the stopper 20 to slide in the vertical direction as described above, it has a narrower width with less flexibility than the vertical groove 19 provided in the tappet 17. Stopcock 2 as much as sex allows
The clearance with 0 is made small. Further, its length is formed to be approximately the same length as the longitudinal groove 19 for the same reason as the tappet 17. In addition, 2
2a and 22b indicate open end faces of the cut retainer 21.

As shown in FIG. 3, an opening 23 is provided on one side of the cylinder body 15 and communicates with the hole 16 so that the tappet 17 can be inserted into the hole 16. A tappet cover 24 for closing the opening 23 is detachably provided, and a stopper 20 projecting into the hole 16 is provided on the back surface of the tappet cover 24. The contact portion 20a at the tip of the stopper 20 is connected to the camshaft 2 when the tappet cover 24 is attached to the cylinder body 15.
The direction is set to be exactly orthogonal to the direction of the rotation axis of No. 5. Note that the stopper 20 does not necessarily need to be provided on the tappet cover 24, and in the case of a type in which the tappet 17 is slid from above the hole 16, the stopper 20 is not necessarily provided in the opening 2.
3 is not provided, so it will be provided directly on the cylinder body 15. Therefore, when the stopcock 20 is simply referred to as the cylinder body 15, it is used to include the tappet cover 24.

The components configured as described above are assembled in the following manner. Ring-shaped retainer 21
is inserted into the tapepet 17 so that the position of the vertical slit 22 approximately coincides with the longitudinal groove 19 of the tapepet 17. The fitted retainer 21 is pressed against the inner circumferential wall of the tapepet 17 while expanding its open end surfaces 22a and 22b due to its elastic force.
Together with this crimped ring-shaped retainer 21,
The tappet 17 is engaged into the hole 16 through an opening 23 provided in the cylinder body 15. Then, in order for the tappet cover 24 to close the opening 23, the abutting part 20a at the tip of the stopper 20 is inserted into the tappet 17 engaged in the hole 16, the longitudinal groove 19 of the retainer 21, and the vertical slit 22. The cylinder body 15 is attached to the cylinder body 15 by being locked while being rotated.
Thus, a rotation stopper device for the tapepet 17 according to the present invention is constructed.

The operation of the anti-rotation device constructed as described above will now be described. First, when assembling, the ring-shaped retainer 21 is fitted into the tapepet 17 in advance, and the vertical groove 19 and the vertical slit 22 are approximately aligned, and the vertical slit 22 is narrower than the vertical groove 19. Therefore, a step 26 is formed between the two (FIG. 4). Therefore, this step 26 serves as a guide for the contact portion 20a at the tip of the stopper 20 when installing the tapepet cover 24, so that the vertical slit 2
2. Despite the narrow width, insertion is done smoothly,
Tappet 17 and stopcock 2 during engine assembly
The trouble of matching with 0 is eliminated. Note that it is even more effective to provide a taper 27 at the opening edge of the longitudinal groove 19.

Next, a case will be described in which the internal combustion engine is operated after being assembled to the cylinder body 15. In the non-lift stroke, the tappet 17 is allowed to rotate around the axis within the width of the longitudinal groove 19, so during the rolling contact between the roller 18 and the cam 28, the tappet 17 tends to deviate from its normal position. . on the other hand,
Due to its elasticity, the retainer 21
radially outward pressing force against (static frictional force)
demonstrate. When the load in the direction of rotation of the tappet 17 exceeds the pressing force, the retainer 21 that has been locked to the stopper 20 slides on the tappet 17, but at this time, the dynamic force that resists the sliding Generates frictional force. These frictional forces suppress the turning movement. And since the force that tries to turn when not lifting is extremely weak, once it is in the correct position when it shifts to lift, the amount of deviation from there will gradually be attenuated, and it will return to its normal position even when not lifting. It is converged as follows. Therefore, the positional relationship between the cam 28 and the roller 18 becomes stable as the cam 28 rotates several times.

Furthermore, although the vertically long groove 19 provided in the tappet 17 is wider than the vertical slit 22 of the ring-shaped retainer 21, the turning angle of the tappet 17 can be restricted within the range of the width, so that in the unlikely event that the ring-shaped retainer 21 Even if a failure occurs, fatal rotation of the tappet 17 can be prevented.

In this way, the degree of freedom in the width direction of the longitudinal groove 19 provided in the tappet 17 can be made greater than in the past by simply crimping the ring-shaped retainer 21 having a predetermined elasticity on the tappet for an internal combustion engine. The drawback that matching the tappet 17 and the stopper 20 is troublesome is eliminated.

Further, since the ring-shaped retainer 21 has a predetermined elasticity, it can be easily attached to the tapepet 17 by reducing its diameter.

Furthermore, even if it cannot be installed in the correct position at the time of installation, the force for turning to the normal position during the lift stroke is sufficiently large due to the pushing force, so that it is set by exceeding the frictional force.
Therefore, precision is not required during assembly and mass production is possible.

Furthermore, after the positional relationship of the tappets has been adjusted, the vertical slit 22 of the ring-shaped retainer 21 has a reduced degree of freedom in its width direction, so that the swing play can be minimized, and the stopper 20 does not directly contact the longitudinal groove 19 of the tappet 17, so that wear and damage of the longitudinal groove 19 can be prevented. Even if wear occurs on the opening edge of the vertical slit 22, it is only necessary to replace the retainer 21, which is extremely convenient.

[Effects of the invention] In summary, the present invention provides the following excellent effects.

(1) Since a ring-shaped retainer with a predetermined elasticity is provided inside the tappet, the pivoting movement of the tappet around its axis during the non-lift stroke is braked by the frictional force generated between it and the inner peripheral wall of the tappet. , it is possible to correct the deviation from the normal position and prevent uneven contact between the cam and the roller. In addition, since the stopper is in direct contact with the vertical slit of the retainer, which has a small clearance in the width direction, there is no impact on the vertical slit in the rotation direction (width direction), and wear on the slit can be suppressed as much as possible. Since the longitudinal grooves of the tappets are only indirectly abutted, there is no wear or damage to them, and therefore reliability can be improved.

(2) Since the vertical groove of the tappet is larger than the vertical slit of the retainer, the vertical groove has the role of guiding the stopper to the vertical slit, making it easy to engage the tappet with the cylinder body hole, and as mentioned above. Since the tappet position is automatically adjusted after assembly, assembly is easy and mass productivity is improved.

(3) It has a simple structure and can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway vertical sectional view showing the main parts and valve mechanism of a conventional internal combustion engine, FIG. 2 is an exploded perspective view of a preferred embodiment of the roller tappet detent device according to the present invention, and FIG. The figure is a partially cut away vertical cross-sectional view showing how the same embodiment is assembled to the cylinder body, and FIG. 4 is a front view of the tappet as seen from the right in FIG. 3. In the figure, 15 is a cylinder body, 17 is a tappet, 18 is a roller, 19 is a longitudinal groove, 20 is a stopper, 21 is a ring-shaped retainer, 22 is a vertical slit, and 28 is a cam.

Claims (1)

[Scope of utility model registration request] A roller provided at the tip of the tappet and a cam that engages with the roller are provided on the axis in the lifting direction, and a vertical groove is formed in the tappet to be loosely fitted into a stopper protruding from the cylinder body. A ring-shaped retainer having a vertical slit narrower than the longitudinal groove is crimped onto the inner circumferential wall of the tapepet so that the stopper is inserted into the vertical slit, and the retainer is attached to the retainer in a non-lifting stroke. 1. A rotation stopper device for a roller tappet, characterized in that the rotation stopper device for a roller tappet is provided with elasticity for braking the turning movement of the tappet about the axis line by a frictional force generated between the tappet and the inner circumferential wall.