KR20120085008A - Engine caliper having micro texturing structure - Google Patents

Abstract

The present invention relates to an engine caliper machined with fine roughness for the purpose of improving the durability of the engine valve train by reducing wear and friction of the upper surface of the engine caliper. The fine roughness of the upper surface of the caliper according to the present invention improves the lubrication conditions of the two surfaces in contact with each other, thereby reducing wear on the upper surface of the caliper, and reducing the wear of the engine valve guide by reducing friction between the two surfaces. The fine concavo-convex region of the upper surface of the caliper according to the present invention includes the entire region of the contact portion between the caliper and the rocker arm, and the fine concave-convex shape is a straight microgroove having a correlation with the sliding direction between the caliper and the rocker arm.

Description

Caliper for engine with fine uneven structure {ENGINE CALIPER HAVING MICRO TEXTURING STRUCTURE}

The present invention relates to a technique for reducing friction and wear by processing the fine concavo-convex on at least one of the two surfaces of the linear reciprocating motion and the sliding motion relative.

In general, when the contact surface pressure is high on the two surfaces where relative motion occurs and the sliding speed of the relative motion is low, the two contact surfaces are in a mixed lubrication state in which solid contact or boundary lubrication is mixed. In this mixed lubrication state, it is easy to cause a rapid temperature rise in the minute regions of the two surfaces by the solid contact. This rise in temperature causes plastic deformation and fatigue failure on both surfaces, whereby particles falling off one of the two surfaces become wear particles, increasing friction and wear on the contact surface.

Therefore, in recent years, in order to improve the lubrication performance of the two contact surfaces in relative motion in the mixed boundary lubrication state, a lot of methods have been recently attempted to process the fine irregularities on the surface. The method of processing such fine irregularities on the surface includes a method using a laser (LST), a machining method using a machine tool, and an ion using electrical and physical energy of ions dissociated from gases in a vacuum state. There are beam processing methods and processing methods through semiconductor etching processes.

The fine concavo-convex processed on the surface through the above-described processing method is known to have a fluid dynamic pressure effect, the role of the reservoir of lubricating oil, the function of capturing wear particles, etc. and has been studied in various fields due to this effect.

The key to the technology of minimizing friction and wear through the micro uneven processing is to determine the shape of the uneven and the arrangement method according to the operating conditions of the mechanical element to be applied. At this time, the shape and arrangement of the concavities and convexities that minimize the friction and wear are greatly affected by the operating conditions and physical constraints such as the contact form of the two moving objects, the working load, the sliding speed, etc. There is a great difficulty in finding the optimal point. In the case of the engine caliper, due to the kinematic constraints when it is installed, the linear reciprocating motion and the sliding motion occur simultaneously, and the contact surface pressure between the two surfaces is high and the sliding speed is relatively low, so the two contact surfaces are in solid contact or boundary lubrication state. Is mixed mixed lubrication state. In addition, due to the high temperature operating environment, the viscosity of the lubricant is low, so the friction and wear environment on the upper surface of the caliper is worse. In order to improve the friction and wear of the upper surface of the caliper, rolling bearings are used in the rocker arm or a hard material is inserted into the contact surface of the caliper with the rocker arm to reduce friction and wear between the two contact surfaces. However, when roller bearings are used in the above-mentioned methods, the valve train inertial mass is increased to increase the load of the valve spring required for the normal dynamic behavior of the valve train, and inserting dissimilar materials into the calipers is a productivity aspect or an economic aspect. Considering this, there is a disadvantage in the application.

The present invention determines the shape and arrangement of the fine concavo-convex in consideration of the characteristics (sliding direction and distance) of the actual caliper contact surface for the engine, unlike the conventional application technique (change of the contact mechanism, change of the contact surface material) and lubrication performance of the contact surface through This technology significantly reduces friction and wear, thereby extending the endurance life of the engine valve train.

The caliper of the engine is one of the valve train components and is located between the valve and the rocker arm to transfer the rotational input of the cam to the valve. The rotational motion of the cam is ultimately represented by the linear reciprocation of the valve, and the caliper in contact with the valve also causes the linear reciprocation along the valve. However, the rocker arm rocking motion (reciprocating rotation of the rocker arm around the rocker arm shaft) causes sliding contact on the contact surface between the caliper and the rocker arm, which causes friction and wear on the upper surface of the caliper. If wear of the caliper upper surface occurs, the valve clearance (engine valve clearance set a certain gap in consideration of the thermal expansion and wear of the valve train) can increase the stable dynamic behavior of the valve train. In general, when the valve clearance is increased by a certain amount, the valve stroke becomes large, the variable load between the valve train components increases, which promotes abrasion of each perturbation part, and the combustion characteristics of the engine worsens. In addition, the frictional force on the upper surface of the caliper caused by the sliding movement of the caliper and rocker arm acts as a side load when the valve reciprocates linearly, promoting wear on the valve tip, valve stem, valve guide, etc. and preventing the rotation of the valve. Acts as. As described above, in order to reduce friction and wear between the caliper and the rocker arm, a rolling bearing is used in the rocker arm or a technique of inserting a different material into the caliper is used. However, these techniques may lead to an increase in rocker arm mass or an increase in the cost of refurbishing. Therefore, in the present invention, to reduce the wear and friction of the caliper and the rocker arm through the fine roughness technology without changing the structure and material of the valve train. When the fine rugged surface is processed on the caliper, the lubricant remains in the rugged surface, which improves the lubrication of the contact surface, thereby reducing friction and wear of the caliper and rocker arm. However, when too much fine irregularities are processed so that the area of the contact portion in which the fine irregularities are not processed is too small, the surface pressure of the contact portion may increase, thereby deteriorating friction and wear characteristics. Moreover, the improvement effect may be insignificant if the shape and arrangement of the unevenness are not appropriate.

An object of the present invention is to reduce the wear and friction of the caliper by processing the fine irregularities on the upper surface of the caliper of the portion corresponding to the contact surface between the caliper and the rocker arm to improve the lubrication characteristics between the caliper and its mating parts.

In the present invention, it is intended to present the optimum uneven shape that can reduce the friction and wear of the upper caliper.

In order to achieve the above object, the present invention provides an engine caliper (2) having a rocker arm contact area (CA) in contact with the rocker arm (1) on the upper surface, at least a part of the rocker arm contact area (CA) A plurality of irregularities are formed in the region of.

In addition, the shape of the unevenness is characterized in that the shape of the fine groove (20).

The angle A of the microgroove 20 is preferably 60 ° to 90 ° with respect to the sliding direction CD of the caliper 2 and the rocker arm 1.

In addition, the line width (W) of the microgroove 20 is characterized in that 50 ~ 150 ㎛, more preferably 50 ~ 130 ㎛.

In addition, the interval P of the microgroove 20 is characterized in that 100 ~ 300 ㎛, more preferably 120 ~ 260 ㎛.

And it is preferable that the depth D of the microgroove 20 is 50 micrometers or less.

The present invention forms a processing region of the fine concavo-convex at least in the entire range (CA) that can be in contact with the caliper (2) and the rocker arm (1) to capture wear particles that accelerate the wear of the caliper (2), It serves to supply lubricant in the situation, and serves to increase the oil film pressure between the caliper 2 and the rocker arm 1, which is advantageous in reducing wear and friction on the upper surface of the caliper 2.

In addition, having the shape of the fine irregularities in the form of fine grooves 20 to correlate with the sliding direction (CD) improves the ability to generate the fluid dynamic pressure effect of the friction surface, and also has excellent ability to trap wear particles and store lubricants.

In addition, when the angle A of the fine groove is 60 ° to 90 ° with respect to the sliding direction CD between the caliper 2 and the rocker arm 1, the wear of the upper surface of the caliper 2 is reduced and the valve guide wears. Excellent reduction effect

In addition, wear of the upper surface of the caliper 2 is that the line width W of the microgroove 20 is 60 to 130 μm, the microgroove spacing P is 100 to 220 μm, and the microgroove depth D is 50 μm or less. And friction can be minimized.

1 is a schematic diagram showing an operation relationship between a caliper and a rocker arm of an engine according to the prior art
Figure 2 is a schematic diagram showing the microgroove structure of the upper surface of the caliper of the engine according to the present invention
Figure 3 is a schematic diagram showing the arrangement relationship between the microgroove structure of the upper surface of the caliper of the engine and the sliding direction of the rocker arm according to the present invention
Figure 4 is an embodiment applying the microgroove of the caliper upper surface of the engine according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the following description, 'micro groove' means a structure in which a plurality of irregularities are repeatedly arranged, and the line width (W) of each irregularities is 150 µm or less, and the interval P of each irregularities is 300 µm or less, and each irregularities The depth D is defined as an uneven structure of 50 µm or less.

The machining area of this microgroove comprises at least the contact area CA of the caliper and rocker arm of FIG. 1, the angle of the microgroove being defined as A of FIG. 3, which is defined by the caliper 2 and the rocker arm 1. It is an angle A between the sliding contact direction (CD) of the () and the microgroove 20. The present invention forms a fine groove (20) considering the orientation on the upper surface of the engine caliper (2) to improve the wear of the upper surface of the caliper (2) and at the same time improve the friction between the caliper (2) and the rocker arm (1) In order to improve the wear of the engine valve guide.

In the present invention, fine irregularities were processed on the upper surface of the engine caliper 2 as shown in FIG. 2 for the purpose of improving friction and wear of the engine caliper 2. The caliper 2 for the engine generates not only linear reciprocating motion but also rocker arm 1 and sliding motion at the same time. Therefore, in consideration of the sliding contact length CL between the caliper 2 and the rocker arm 1, it is necessary to select a machining site so that at least the contact area CA of the caliper 2 and the rocker arm 1 is included. . And the caliper (2) is in contact with the rocker arm (1) as well as linear reciprocating motion is to perform a sliding reciprocating motion. In the case of the irregularities existing on the sliding contact surface, the lubricating performance of the contact surface varies according to its shape and direction. A similar example is that the friction and wear characteristics vary depending on the honing angle of the cylinder liner. Therefore, in the present invention, to minimize the friction and wear of the upper surface of the caliper (2) through the microgroove 20 having a certain angle (A) with respect to the sliding direction (CD) between the caliper (2) and the rocker arm (1). .

[Experiment 1: Caliper  Depth measurement of upper surface]

Table 1 is a test example for evaluating the wear performance of the microgroove 20. Table 1 uses the line width (W), spacing (P), angle (A), and depth (D) of the microgrooves 20 as variables, and measures the shape of the caliper top surface 20 as a result. Indicated. As a result of the test, as the angle (A) formed between the microgroove 20 and the sliding direction (CD) of the upper surface of the caliper (2) increases, the wear of the caliper (2) decreases in most results. It was also the largest. The microgroove depth (D) was analyzed as the smallest influencer in the test area.

Psalter Microgroove Design Variables Average data Line width
(W, μm) interval
(P, μm) Angle
(A, deg) depth
(D, μm) Wear depth
(Μm,%) Reference specimen - - - - 3.73 Psalm 1 50 100 30 10 2.51 (32.7% ↓) Psalm 2 50 200 60 20 1.73 (53.6% ↓) Psalm 3 50 300 90 50 1.91 (48.8% ↓) Psalm 4 100 100 60 50 1.66 (55.5% ↓) Psalm 5 100 200 90 10 1.45 (61.1% ↓) Psalm 6 100 300 30 20 2.72 (27.1% ↓) Psalm 7 150 100 90 20 1.80 (51.7% ↓) Psalm 8 150 200 30 50 2.65 (29.0% ↓) Psalm 9 150 300 60 10 2.05 (45.0% ↓)

In other words, compared to the reference specimen without the microgroove structure, the specimens 1 to 9 having the microgroove structure reduced the wear depth by 27.1% to 61.1%. The presence of the microgroove reduced the wear of the engine caliper. It can be seen that the effect is significantly improved.

When analyzing the fine groove design structure of specimens 1 to 9, the line width (W) of the fine grooves is 50 to 150 μm, the spacing (P) of the fine grooves is 100 to 300 μm, and the depth (D) of the fine grooves 20 is It can be confirmed that designing to 50 μm or less is preferable.

In addition, the most optimized fine groove design structure has a line width (W) of the fine grooves of 50 to 130 μm, a spacing (P) of the fine grooves of 120 to 260 μm, and a depth (D) of the fine grooves 20 of 50 μm or less. It was confirmed.

Experiment 2: Valve Guide Bore  Change measurement]

To evaluate the friction reduction effect of the microgroove 20 formed on the upper surface of the caliper 2 by applying the result obtained in the effect test 1, the wear of the valve guide was evaluated. As described above, the frictional force between the caliper 2 and the rocker arm 1 acts as a side load that hinders the linear movement of the valve. Therefore, abrasion occurs between the valve stem and the valve guide. Table 2 is an example in which the specimen of Example 1 was applied to the engine to evaluate the wear of the valve guide.

Psalter Microgroove Design Variables Average data Line width
(W, μm) interval
(P, μm) Angle
(A, deg) depth
(D, μm) Guide bore change
(Μm,%) Reference specimen - - - - 8.6 Psalm 5 100 200 90 10 4.6 (46.5% ↓) Psalm 10 100 300 60 10 5.5 (36.0% ↓) Psalm 11 150 100 30 50 7.1 (17.4% ↓)

More specifically, when comparing specimens 5, 10 and specimen 15, the angle A of the microgroove 20 is 60 ° to 90 ° with respect to the sliding direction CD of the caliper 2 and the rocker arm 1. In the case that the guide inner diameter change rate is more than 36.0%, while when the angle A of the microgroove 20 is 30 °, the guide inner diameter change rate is only 17.4%, so the angle A of the microgroove 20 is a caliper ( It can be seen that the wear reduction effect is further maximized in the case of 60 ° to 90 ° with respect to the sliding direction (CD) between 2) and the rocker arm (1).

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention.

That is, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the scope of the technical spirit of the present invention by these embodiments.

Therefore, the protection scope of the present invention should be interpreted by the claims below, and all technical ideas within the equivalent scope will be construed as being included in the scope of the present invention.

The present invention forms a plurality of fine grooves 20 having a predetermined angle with respect to the friction area between the engine caliper (2) and the rocker arm (1) to the engine caliper (2) and rocker arm (1) By reducing friction and abrasion between them, it is possible to reduce wear of the caliper upper surface 2 and at the same time reduce wear of the valve guide.

1: rocker arm
2: caliper
20: Fine groove on top of caliper
CA: contact area between caliper and rocker arm
CD: Sliding contact direction between caliper and rocker arm
CL: sliding contact length of caliper and rocker arm
D: Depth of Caliper Microgroove
W: width of caliper microgroove
P: Spacing between caliper microgrooves
A: Angle between caliper microgroove and CD

Claims (6)

An engine caliper (2) having a rocker arm contact area (CA) in contact with the rocker arm (1),
An engine caliper (2), characterized in that a plurality of irregularities are formed in at least part of the rocker arm contact area (CA). The method of claim 1,
The unevenness is an engine caliper (2), characterized in that the fine groove (20) form. The method of claim 2,
Caliper (2) for the engine, characterized in that the angle (A) of the microgroove 20 is 60 ° ~ 90 ° with respect to the sliding direction (CD) of the caliper (2) and the rocker arm (1) The method of claim 2,
Engine caliper (2), characterized in that the line width (W) of the fine groove 20 is 50 ~ 150 ㎛. The method of claim 2,
The caliper (2) for the engine, characterized in that the interval (P) of the microgroove 20 is 100 ~ 300 ㎛. The method of claim 2,
Depth (D) of the microgroove 20 is an engine caliper (2), characterized in that less than.

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