JPH06307212A - Valve spring retainer - Google Patents

Abstract

PURPOSE:To prevent breakage caused by the sinking of a valve and the repeated collisions by decreasing inertia force to be generated with the reciprocating motion of a valve stem through a process of inserting an iron-system cylindrical sleeve having the same taper shape as that of the inner peripheral part into a valve spring retainer made of aluminum. CONSTITUTION:A retainer main body 7 of a valve spring retainer 6 takes AA2618 alloy as a base material, to which ceramics powder is added and mixed so as to be formed into pressed powder forming body. And it is machined after the hot extruding so as to be formed into the fixed shape after the softening process, and then the hardening process is applied thereto. A sleeve 8 is formed into the fixed shape by providing the taper angle on the inner periphery by the press working and is hardened by using chrome steel. Thereby the sinking of a valve caused by insufficient is compensated, the extending force to be applied to the retainer through a cotter is received by the sleeve, and the retainer is prevented from being cracked exactly in half caused by the insufficient strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve spring retainer used in a valve mechanism of an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art FIG. 6 shows an outline of a structure of a valve train in a conventional automobile engine (here, an example of a direct drive system). As shown in FIG. 6, a valve spring retainer (hereinafter referred to as a retainer) 1 is used in a valve operating mechanism of an internal combustion engine, and is fixed to a shaft end portion of a ferrous valve stem 2. The opening and closing of the valve at the tip of the valve stem 2 by the cam mechanism is performed by pressing the valve stem 2 against the cam 3 and moving the valve stem 2 up and down to follow the cam by the elastic force of the valve spring 4. In order to transmit the elastic force of the valve spring 4 to the valve stem 2,
The valve spring 4 is arranged by fixing the retainer 1 to the shaft end of the valve stem 2 via an iron-based cotter 5 having a split structure, and using the retainer 1 as a spring seat. The shaft end portion of the valve stem 2 on the combustion chamber side is enlarged like a trumpet and serves as a valve in contact with the valve seat (neither is shown).

An outer peripheral portion 5-a of the cotter 5 having the split structure.
Has a tapered shape, and the inner peripheral portion 1-a of the retainer 1 that supports one end of the valve spring 4 also has a tapered shape, and these are pressed in and fixed by the pressing force of the spring acting on the retainer. . In addition, cam 3
With the vertical movement of the valve due to
In a, 1-a), the impact force due to the jump, the bounce, or the repeated impact force acts via the cotter, so that the retainer 1 does not have the strength and the rigidity to withstand this. , Valve depression,
Or it will cause a split into two.

As this retainer, conventionally, carbon steel, chrome steel, or the like that has been carburized and quenched has been used. However, recently, there is a strong demand for higher output and lower fuel consumption of automobile engines, and as a solution to this, the weight of valve trains is being reduced. Reducing the weight of the valve retainer, which is one of the valve train components, is an effective means for satisfying the above requirements due to the reduction in inertial weight and the accompanying reduction in spring load, which results in low friction. Therefore, in order to reduce the weight of the valve retainer, the conventional production of an aluminum alloy from an iron-based material is becoming a solution.

However, aluminum alloys have lower strength and rigidity than iron-based materials, and accordingly, various problems have arisen in the practical application of valve retainers made of aluminum alloys. For example, the valve retainer is supported by the valve stem by the cotter and the tapered surface, and the compression force of the valve spring and the cam strike the valve stem, causing the valve stem to sink due to sliding on the contact surface of the cotter and the retainer. Occurs. Also, when a strong impact force is applied to the valve stem due to abnormal movement of the valve operating system such as japs and bounces, the valve stem sinks and
Along with this, expansion force is applied to the retainer via the iron-based cotter. As a result, aluminum alloy lacks strength and rigidity as compared with iron-based alloys, so the valve stem will fall out due to the valve stem sinking, or the retainer will split into two due to the expansion force, and as an engine, Fatal is also a problem. About this two cracks,
Since the cotter has a split structure, the edge portion of the iron-based cotter causes stress concentration on the inner peripheral surface of the retainer. That is, due to the stress concentration of the expansion force, the fracture occurs from this portion, and specifically, the lower end portion of the inner peripheral surface of the retainer that is in contact with the edge portion of the cotter is used as the starting point of the fracture (see FIG. 7).

As the next problem, the pressing force of the valve spring acts on the lower surface of the retainer umbrella portion (also referred to as a flange portion), and further sliding with the end portion of the valve spring occurs, which causes wear of the retainer. come. Further, the pressing force of the valve spring may cause stress concentration on the root portion of the retainer umbrella portion, and further, fatigue fracture may occur due to the influence of notch sensitivity and the like.

With respect to the above problems, conventionally,
Various solutions have been proposed to approach the performance of ferrous valve retainers. For example, JP-A-1-195905
In the publication, by forming a remelting treatment layer and a TiN layer on the taper surface on the inner peripheral side of the aluminum alloy retainer that is in contact with the outer peripheral surface of the cotter, the strength and wear resistance are improved, and the valve stem sinks, breaks, etc. It is presented as a solution to the problem. Also, Japanese Utility Model Laid-Open No. 61-136106 discloses that a reinforcement portion is provided mainly by increasing the thickness of the lower part of the retainer made of an aluminum alloy as a measure against the depression of the valve stem due to insufficient strength and rigidity. Further, as an example of the strength of the retainer umbrella portion and a measure against wear, the actual open sho 62-6
0907 and JP-A-1-138308,
In Japanese Utility Model Laid-Open No. 63-24311, a steel plate or a reinforced layer is provided on the surface of the retainer umbrella portion which is in contact with the valve spring to improve strength and wear resistance. And, JP-A-63-50613 and 63
No. 50614 discloses a metal composite member using a ceramic reinforcing material, and the same reinforcing measure is applied.

[0008]

As described above, many proposals have been made to eliminate the stress concentration due to the cotter on the retainer and the destruction of the retainer due to fatigue, but the present invention is different from these proposals. By making a new proposal, the problem to be solved is to solve the problems of the conventional technology and bring it closer to the performance of the iron-based retainer.

[0009]

The present invention provides a solution to such a problem, which is more effective than the above solution and can be easily implemented at a low cost. , Specifically, regarding the retainer made of aluminum alloy, as a means for solving the problem of the valve sinking due to lack of rigidity and strength or the splitting of the retainer into two parts, , An outer peripheral side having the same tapered shape, and an inner peripheral side is inserted with an iron-based cylindrical sleeve having the same tapered shape as the outer peripheral part of the cotter. ,
An umbrella-shaped lock is used to compensate for the sinking of the valve due to insufficient rigidity, and the expansion force applied to the retainer via the cotter is received by this sleeve, preventing the retainer from splitting into two due to insufficient strength. Since the sleeve is thin, it does not impair the weight reduction due to aluminum alloying.

In addition, the aluminum alloy forming the retainer of the present invention is disclosed in Japanese Patent Application No. 2-325328.
It is preferable to use an alloy excellent in high-temperature strength, impact strength, and wear resistance as described in Japanese Patent Publication No. Since this alloy contains ceramic powder on the basis of rapidly solidified powder, it has a dense structure, has both high strength and high toughness, and has excellent sliding characteristics. Also in the present invention, if the base alloy is tough, more excellent effects can be exhibited. Of course, the retainer may be made of an AA2000-based alloy or the like, depending on the engine specifications in which the retainer is used.

A member according to the above-mentioned Japanese Patent Application No. 2-325328 or a member in which ceramic particles are added to an AA2000-based alloy to improve wear resistance has high strength,
In a retainer formed of an aluminum alloy having both high toughness and wear resistance, the present invention is achieved by inserting a taper-shaped iron-based sleeve suitable for this into the tapered inner peripheral surface of the retainer in contact with the cotter. Become. This sleeve is made of carbon steel, chrome steel, etc., which has been subjected to carburizing and quenching treatment, etc., and has a shape that follows the taper shape of the inner peripheral surface of the retainer on the outer peripheral side of the sleeve and the inner peripheral side of the sleeve. The taper shape is basically
The taper angle should be the same as the inner peripheral surface of the retainer, and should follow the taper shape on the outer peripheral side of the cotter. Preferably, the upper end portion (here, the umbrella portion side of the retainer upper portion) of the sleeve has an umbrella shape and is locked to the upper surface of the retainer. To install it, insert it from the top of the retainer, and then install the valve through the cotter. Since the sleeve has the same taper angle as the inner peripheral surface of the retainer, it does not fall out of the retainer, and since the sleeve has the same taper angle as the outer peripheral surface of the cotter, the valve does not fall out. In addition, since the upper end of the sleeve is locked by the umbrella portion, it is made stronger. Therefore, it is not necessary to fix the sleeve to the inner peripheral surface of the retainer.

If the sleeve interferes with other parts, a groove along the umbrella shape may be provided in advance on the upper surface of the retainer, and the umbrella portion of the sleeve may be fitted to this portion by a predetermined pressure. . Although the effect of preventing the valve from sinking is slightly reduced, if it is desired to prevent damage due to the splitting into two due to the stress concentration of the expansion force, the umbrella lock at the upper end of the sleeve is abolished and the shape is simplified. , It may be inserted in the same manner. At this time, in order to obtain the effect of preventing the sinking, the surface roughness of the outer peripheral surface of the sleeve and the inner peripheral surface of the retainer are roughened, and the sliding of the sleeve is prevented by increasing the frictional force. Of course, if there is another means for fixing the sleeve and the retainer, that means may be used. As described above, these are mainly described on the premise of the manufacturing process by forging the retainer, but of course, the retainer may be implemented by an aluminum alloy cast stuffed iron sleeve.

[0013]

EXAMPLES The present invention products will be described below with reference to specific examples. FIG. 1 shows an example of a valve spring retainer 6 according to the present invention. Retainer body 7 is AA261
Eight alloys were used as the base material, and the manufacturing method was the rapid solidification powder method, and the ceramic powder was added and mixed. This is made into a powder compact, which is hot extruded, machined into a blank shape, subjected to softening treatment (350 ° C x 10 hours), and then cold forged into a predetermined retainer shape, followed by hardening treatment (500
C. × 2 Hr → water-cooled solution treatment, 175 ° C. × 10 Hr aging treatment).

The sleeve 8 to be inserted into the retainer body 7 shown in FIG. 3 is formed into a predetermined shape by forming the retainer inner peripheral surface and the cotter outer peripheral surface at the same taper angle by press working or the like. In this embodiment, the wall thickness is 0.5
mm, made of chrome steel, and hardened by carburizing and quenching. Further, here, in consideration of preventing the valve from sinking, the surface roughness of the sleeve outer peripheral surface and the retainer inner peripheral surface is set to Ra10 μm or more (usually Ra: about 6 μm),
Friction force is used to prevent the valve from sinking. The thickness, the quenching method, etc. can be selected at any time depending on the material used and the specifications of the engine actually used.

FIG. 2 shows an example of the present invention as a second embodiment. The retainer body 7 is obtained by using the same material and manufacturing method as the retainer 6 shown in the first embodiment. The material and manufacturing method of the sleeve 8 ′ are the same, but here, the upper end of the sleeve 8 ′ (upper side of the retainer:
The portion corresponding to the umbrella portion side) is made into the umbrella portion 9 by pressing or the like. By mounting the umbrella portion 9 in advance at a predetermined position on the upper portion of the retainer provided with a groove along the shape of the umbrella portion, the effect of the first embodiment against the depression of the valve is further enhanced.

As described above, in the embodiment of the present invention, by mounting the iron-based sleeve shown in the above-mentioned embodiment, the valve sinks or the two splits due to the expansion force from the cotter has high strength and high rigidity. The above problem disappears because it is received by the hard iron sleeve. In addition, the retainer umbrella part that slides in pressure contact with the valve spring is
High strength and high toughness AA261 by rapid solidification powder method
By using 8 materials and dispersing the ceramic powder in the base, the problem of wear resistance is eliminated, and the base base is
Due to its high toughness, it was less susceptible to notch sensitivity and other factors, and was less prone to cracking.

Next, in order to confirm the effect of the product of the present invention, an impact test was carried out using a retainer body, and the presence or absence of impact damage due to impact load was compared. The tester is of a falling weight type, in which the weight is dropped from the top, and a weight of 2 kg is applied from a height of 1000 mm to a punch 1
Repeated impact load was applied to the valve end through 0 (Fig. 4).
reference). The retainer used for the test is the same material as shown in the examples except for the examples 1 and 2 which are the products of the present invention, a comparative example 1 without a sleeve, and a conventional iron-based retainer. Was used as Comparative Example 2. The cotter 5 is a conventional product. The results are shown in Table 1.

[0018]

[Table 1]

According to this, it can be seen that the iron-based retainers of Examples 1 and 2 and Comparative Example 2 did not suffer from breakage due to a double crack. On the other hand, in Comparative Example 1, stress concentration due to the expanding force occurs in the retainer inner peripheral surface and the edge portion of the cotter end, and as a result, the retainer is cracked starting from this portion. As described above, it is understood that the product of the present invention has the same strength and reliability as the iron-based retainer.

Further, as a test for confirming the effect of the product of the present invention, the amount of depression of the valves was compared by repeatedly applying an impact load. The tester and method are almost the same as the above test, except that the weight is 2 kg and the height is 10
After dropping from 0 mm and repeating this 10 times, the amount of depression of the valve was measured. The retainer used for the test is the same as above, and the retainers used in Examples 1 and 2 and Comparative Example 1, respectively.
It was set to 2.

The results are shown in FIG. As a result, in the iron-based retainer of Comparative Example 2 and the retainer of Example 2, the valve did not sink even when the impact load was repeatedly applied 10 times. On the other hand, it can be seen that the valve of Comparative Example 1 not equipped with the sleeve has a large amount of valve depression. That is, the inner peripheral portion of the retainer is expanded and deformed by the force of the valve trying to sink and the expanding force generated through the cotter. In Example 1, a slight subsidence was confirmed due to the sliding of the sleeve, but it was at a level without a problem, and it was confirmed by an impact test that it did not result in breakage. Further, this can be solved by increasing the frictional force and preventing the sleeve from slipping by obtaining the optimum value of the surface roughness of the outer peripheral surface of the sleeve which is in contact with the inner peripheral surface of the retainer.

Next, the retainers of these examples and comparative examples were mounted on an actual machine, and a durability test (9
000 rpm × 100 hr, oil temperature 120 ° C.). No damage has occurred in any of the retainers. In Examples 1 and 2, the valve did not sink and the spring did not cause wear, and the performance was equivalent to that of the iron-based retainer. On the other hand, in the retainer of Comparative Example 1, although the wear was not caused, a slight depression of the valve was confirmed, and the impact load due to the abnormal motion of the valve train (here, jump and bounce) was repeatedly applied. If it goes, there is a concern that the valve will sink and it will be destroyed.

[0023]

[Effect] According to the present invention, since the thin iron sleeve is only inserted into the inner peripheral surface side of the aluminum alloy retainer, the inertial force associated with the reciprocating movement of the valve stem is also small, and the retainer and the cotter always move in the same manner. .

[Brief description of drawings]

FIG. 1 is a sectional view of an aluminum alloy valve spring retainer according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an aluminum alloy valve spring retainer according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a retainer body.

FIG. 4 is a schematic diagram showing an impact test method for confirming the effect of the product of the present invention.

FIG. 5 is a graph showing the results of a repeated impact test.

FIG. 6 is a cross-sectional view of a valve operating portion of an internal combustion engine.

FIG. 7 is a diagram showing a state of a broken portion of an aluminum alloy valve retainer.

[Explanation of symbols]

 1 Valve Spring Retainer 2 Valve Stem 3 Cam 4 Spring 5 Cotter 6 Retainer 7 Retainer Main Body 8 Sleeve 9 Umbrella

Claims (2)

[Claims] 1. A valve spring retainer for an internal combustion engine, the main body of which is made of an aluminum alloy, and a taper-shaped iron sleeve adapted to this is inserted into the taper-shaped inner peripheral surface of the retainer which is in contact with the cotter. Characteristic valve spring retainer for internal combustion engines. 2. The valve spring retainer according to claim 1, wherein the sleeve has an umbrella shape.