JPH01240708A - Valve mechanism of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent oil film from being interrupted by making the sum of the moving speed of a contact point with a cam slipper surface on a cam side and the moving speed of the contact point with a cam surface on a rocker arm side positive. CONSTITUTION:Where the moving speed of a contact point P with a cam slipper surface 14 on the side of a cam 10 is Vc and the moving speed of the contact point P with a cam surface 12 on the side of a rocker arm 13 is VF, a valve mechanism is constructed so that 'Vc+VF>0' can be acquired at all the cam angles. Consequently, since the transmission speed of lubricating oil between the cam surface and the cam slipper surface does not become 0, oil film can be prevented from being interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve operating mechanism for opening and closing an intake valve or an exhaust valve of an internal combustion engine mounted on a vehicle or the like.

(Prior Art) Conventionally, as shown in FIG.
A valve operating mechanism for an internal combustion engine is such that an intake valve 5 (or an exhaust valve 6) can be opened and closed by the rocking motion of the rocker arm 3 by sliding the cam slipper surface 4 of the rocker arm 3 on the cam slipper surface 4 of the rocker arm 3. It is publicly known.

(Problems to be Solved by the Invention) This type of valve train has high wear resistance and is unaffected by differences in lubrication conditions depending on the type of lubricating oil or vehicle running conditions. In order to meet the demands for higher performance, lightweight devices are required.

However, in the conventional valve operating mechanism, there was a problem in that the cam surface 2 and the cam slipper surface 4 were easily worn, and the above-mentioned requirements could not be satisfied.

As a result of investigating the cause of such wear, it was found that most of it was adhesive wear due to a break in the oil film.As long as the oil film is out, seizing will occur even if the surface pressure and load are lowered, and the fundamental problem will be solved. It doesn't lead to a solution.

The lack of oil film seems to be somewhat related to the lubrication conditions or vehicle running conditions, but the biggest factor is the moving speed of the contact point between the cam surface of the cam and the cam slipper surface of the rocker arm. This is what the inventors of the present application discovered. That is, in the present invention, the sum of the moving speed of the contact point with the cam slipper surface on the cam side and the moving speed of the contact point with the cam surface on the rocker arm side is set so as to satisfy a certain condition. It is an object of the present invention to provide a valve train mechanism for an internal combustion engine that does not cause an oil film to run out between a cam surface and a cam slipper surface, has high wear resistance, and is lightweight.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a cam slipper surface of a rocker arm in sliding contact with a cam surface of a rotating cam, so that the intake air is In a valve operating mechanism for an internal combustion engine capable of opening and closing a valve or an exhaust valve, a moving speed of a point of contact with the cam slipper surface on the cam side is VC, and a contact point with the cam surface on the rocker arm side is When the moving speed of a point is VF, VC
It is characterized in that it satisfies +VF)O, and (1+I') when expressed in terms of specifications.

(Function) The passage speed of lubricating oil between the cam surface and the cam slipper surface is 0.
This prevents the oil film from running out.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a sectional view of a main part of a valve mechanism for an internal combustion engine according to the present invention, and in the figure, 10 is a cam rotating in the direction of the arrow;
It is integrally formed on the outer periphery of the camshaft 11. The cam 10
The cam surface 12 is the cam slipper surface 1 of the rocker arm 13.
It is in sliding contact with 4. The rocker arm 13 has a pivot 15 at the upper end thereof that is swingably supported by a bearing 16, and a stem slipper surface 17 at the lower end of the other end that slides on the upper end of the stem 18 of the intake valve (or exhaust valve). possible contact. As the cam 10 rotates, the rocker arm 13 swings, causing the stem 18 to reciprocate in the direction of the arrow, opening and closing the intake valve. The basic configuration is the same as the conventional one.

Next, novel points in the present invention that are different from the conventional ones will be explained. FIG. 2 is an explanatory diagram of symbols used in the detailed explanation of the present invention, in which r is the radius of the cam surface 12, 01 is the center of the cam shaft 11, and 02 is the circular arc of the cam slipper surface 14 of the rocker arm 13. 03 is the arc center of the stem slipper surface 17 of the rocker arm 13, 04 is the center of the pivot 15, P is the contact point between the cam surface 12 and the cam slipper surface 14, a
is the radius of the cam slipper surface 14 of the rocker arm 13,
b is the distance between the center 01 of the pivot 15 and the arc center 02 of the cam slipper surface 14 of the rocker arm 13, C is the distance between the center 04 of the pivot 15 and the center 0+of the cam shaft 11, and α1 is the center of the pivot 15. 04 and the arc center o3 of the stem slipper surface 17 of the rocker arm 13, ℃2 is the straight line passing through the center 04 of the pivot 15 and the center 01 of the cam shaft 11, C3 is the center 04 of the pivot 15
and the arc center 02 of the cam slipper surface 14 of the rocker arm 13, Q4 is the straight line passing through the arc center 02 of the cam slipper surface 14 of the rocker arm 13 and the cam surface 1 of the cam IO.
2 and the contact point P between the cam slipper surface 14 of the rocker arm 13, t5 is a common tangent at the contact point P between the cam surface 12 and the cam slipper surface 14, y is a straight line passing through the center O1 of the cam shaft 11, and An axis whose intersection angle with the straight line Q2 is set to φ, X is fixed to the cam 10, and an axis perpendicular to the axis y,
r is the intersection angle between straight lines Q1 and 22, λ is the intersection angle between straight lines C1 and 03, ν is the intersection angle between straight lines 03 and Q4, φ is the intersection angle between common tangent α5 and axis 3 and the axis X.

What is new about the present invention is that the moving speed of the contact point P with the cam slipper surface 14 on the cam 10 side is VC, and the contact point P with the cam surface 12 on the rocker arm 13 side is VC.
When the moving speed of This is what I did.

From the above formulas (1) and (2) Therefore, +a (1-H')>O...(6) That is, ku1+r　　　　　　...(7).

Therefore, at all cam angles, the sum of VC and VF is made to satisfy the above formula (7).

In this way, the passage speed of the lubricating oil between the cam surface 12 and the cam slipper surface 14 will not become zero, and no oil film will run out.

The term "oil film depletion" refers to a case where the passage speed of lubricating oil between the cam surface 12 and the cam slipper surface 14 becomes O.

FIG. 3 is a diagram showing the passage speed of the lubricating oil between the cam surface 12 and the cam slipper surface 14. In the figure, the velocity component of the lubricating oil between the cam surface 12 and the cam slipper surface 14 = O1, that is, when the passing speed is O, the oil film runs out. Looking at the moving speed of the contact point P on the cam surface 12 with the cam slipper surface 14, the oil film breaks when VC=-VF.

FIG. 4 is a diagram showing the relationship between the thickness of the oil film between the cam surface 12 and the cam slipper surface 14 and the position of the contact point between the cam surface 12 and the cam slipper surface 14.

In the figure, point (A) indicates that the peaks of the cam surface 12 are on the cam slipper surface 14.
The point (B) is the point at which the peak of the cam surface 12 has finished sliding contact with the cam slipper surface 14. In the figure, line A is
This is the case when V c + V F < O, and in this case, the thickness of the oil film is zero at two points (c) and (d), that is, the oil film breaks.

Further, line B shows the case where VC+VF=O, and in this case, the oil film breaks at one point (e).

Furthermore, line C is the case of the present invention, that is, the case where VC+VF) is 0. In this case, the thickness of the oil film does not become zero at all cam angles, and no oil film breakage occurs.

FIG. 5 is a comparison diagram showing the results of durability tests conducted on three types of products with different VC and VF conditions based on two types of durability times 2011r and 4011r. In the same figure, A is VC+VF (if 0, B is VC+VF=0
In this case, C is the case where VC+VF>0.

For each of A, B, and C, the one with spots has an endurance time of 2011r, and the one with diagonal lines has an endurance time of 40.
11r results are shown.

As is clear from this figure, in case C of the present invention, the amount of wear on the cam slipper surface 14 is the smallest compared to cases A and B, which are conventional cases, and lubrication is performed well. .

FIG. 6 is a photograph substituted for a drawing showing the durability test results of the cam slipper surface of the rocker arm in the case of conventional A described above and FIG. 7 in case C of the present invention.

As is clear from these figures, in the conventional case, scuffs (scratches) occur over the entire cam slipper surface as shown in Figure 6.
In contrast, in the case of the present invention, as shown in FIG.
There is almost no scuff on the cam slipper surface.

(Effects of the Invention) As described above, the valve operating mechanism for an internal combustion engine of the present invention operates the intake valve or In a valve operating mechanism for an internal combustion engine capable of opening and closing an exhaust valve, let VC be the moving speed of the point of contact with the cam slipper surface on the cam side, and VC be the moving speed of the point of contact with the cam surface on the rocker arm side. When the moving speed is VF, V
It is characterized by satisfying C+VF>O, and satisfying <l+I' when expressed by an equation expressed in terms of specifications.

Therefore, there is no oil film breakage between the cam surface and the cam slipper surface, and wear resistance is high.

By reducing the length of the cam slipper surface of the rocker arm, it is possible to reduce the weight of the rocker arm.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, FIG. 1 is a side view of the main parts of the valve mechanism of the present invention, and FIG. 2 is a valve mechanism used in this embodiment. Figure 3 shows the passage speed of lubricating oil between the cam surface and the cam slipper surface, and Figure 4 shows the thickness of the oil film between the cam surface and the cam slipper surface, and the cam surface and the cam slipper surface. A line diagram showing the relationship between the position of the contact point with the cam slipper surface, Figure 5 is a comparison diagram showing the durability test results of the rocker arm of the present invention and the conventional valve mechanism, and Figure 6 is a diagram showing the relationship between the position of the contact point with the cam slipper surface. FIG. 7 is a photograph showing the durability test results of the cam slipper surface of the rocker arm of the valve train of the present invention, and FIG. 8 is a sectional view of the conventional valve train. 10...Cam, 12...Cam surface, 13...Rocker arm, 14...Cam slipper surface, 17...Intake valve (exhaust valve). Applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] 1. The cam and slipper surface of the rocker arm are brought into sliding contact with the cam surface of the rotating cam, so that the intake valve or the exhaust valve can be opened and closed by the rocking motion of the rocker arm. In the valve operating mechanism of an internal combustion engine, when the moving speed of the point of contact with the cam slipper surface on the cam side is V_C and the moving speed of the point of contact with the cam surface on the rocker arm side is V_F, then V_C+V_F> A valve mechanism for an internal combustion engine, which satisfies the following: ▲A mathematical formula, a chemical formula, a table, etc.▼. However, r: radius of the cam surface a: radius of the cam slipper surface of the rocker arm b: distance between the pivot center and the arc center of the cam slipper surface of the rocker arm c: distance between the pivot center and the cam shaft center Γ: Intersection angle between a straight line passing through the pivot center and the arc center of the rocker arm's stem slipper surface and a straight line passing through the pivot center and the cam shaft center λ: The intersection angle between the pivot center and the arc center of the rocker arm stem slipper surface. Intersection angle between a straight line passing through the center of the pivot and the center of the arc of the cam slipper surface of the rocker arm