JPH02102308A - Valve spring retainer - Google Patents

Abstract

PURPOSE:To increase rigidity of a whole valve spring retainer of a valve operation mechanism by providing a specified form of retainer in which each annular end surface position is varied along the axis of the retainer and forming the thickness of the retainer thicker at the middle of the retainer. CONSTITUTION:A valve spring retainer 15 of a valve operation mechanism is provided with a tapered center hole 20 through which a valve stem 1a passes through a cotter, a No.1 annular end surface 21 holding an outer valve spring 17, and a No.2 annular end surface 22 holding an inner valve spring 18. An axial length L2 from an upper end surface 23a to the No.2 annular end surface 22 is formed longer than half an axial length L1 from the upper end surface 23a to a lower end surface 23b. An axial length L3 from the No.1 annular end surface 21 to the No.2 annular end surface 22 is formed longer than an axial length L4 from the upper end surface 23a to the No.1 annular end surface 21 and than a length L5 from the No.2 annular end surface 22 to the lower end surface 23b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention] <Industrial Application Field> The present invention is directed to a valve stem of an engine intake and exhaust valve for holding a valve spring wound inside and outside each valve stem of an engine intake and exhaust valve. This valve spring retainer is made of forged aluminum alloy and is attached to the valve spring retainer via a cotter.

<Conventional Technology> Conventionally, valve spring retainers used for engine intake and exhaust valves have generally been made of steel.
Since this retainer reciprocates together with the valve, it is preferable to make it as light as possible, and it has been proposed to use, for example, a high-strength aluminum alloy.

However, since aluminum alloys generally have lower rigidity than steel materials, in order to use them as valve spring retainers, it is necessary to increase the rigidity of the structure as much as possible. In particular, in valve spring retainers for intake and exhaust valves in which valve springs are wound on the inside and outside of the valve stem, the rigidity of the annular shoulder surface that serves as the seat surface of the outer valve spring, which has a relatively large spring coefficient, is increased. Although it is necessary, for example, if this part is made thicker, the entire retainer becomes larger and heavier. In addition, although stress tends to concentrate at the corner between the annular shoulder surface that serves as the seating surface of the inner valve spring and the outer surface facing this surface, it is difficult to There is a problem that the wall thickness between the center hole and the center hole is thin, so it tends to be weak. In addition, conventionally, the free end side edge of the valve stem of the central through hole was chamfered, but this not only tends to cause stress to concentrate at the corners, but also causes burrs that may remain at these corners to act as a barrier. This makes it difficult for lubricating oil to enter the central hole, and the temperature of the aluminum alloy retainer, which is relatively prone to thermal expansion, may rise unnecessarily.

On the other hand, in order to form a valve spring retainer from aluminum alloy, the aluminum alloy is first made into a cylinder by extrusion molding, which is then cut into disk shapes and then forged into the desired retainer shape. Since the internal crystals generally extend in the axial direction of the retainer, the retainer tends to be weak against stress in a predetermined direction, making the above problem even more serious.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to provide a valve spring retainer with improved rigidity without increasing weight.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, a pair of valves coaxially wound inside and outside each valve stem of an intake and exhaust valve of an engine is provided. A valve spring retainer made of forged aluminum alloy is attached to the base end of the valve stem via a cotter to hold a spring, the valve spring retainer having a tapered central through hole into which the cotter fits, and the outer valve spring. a first annular shoulder surface formed on the outer periphery as a spring seat of the inner valve spring, and a first annular shoulder surface formed closer to the free end of the valve stem along the axial direction than the first annular shoulder surface as a spring seat of the inner valve spring. and a second annular shoulder surface, and the axial length from one end surface near the valve stem base to the second annular shoulder surface is equal to the axial length from the one end surface to the other end surface. and the axial length from the first annular shoulder surface to the second annular shoulder surface is the axial length from the one end surface to the first annular shoulder surface. This is achieved by providing a valve spring retainer characterized in that the length is longer than the length in the axial direction from the second annular shoulder surface to the other end surface.

<Function> By doing so, the intermediate portion of the retainer becomes thicker and the rigidity of the entire retainer is improved. In addition, the outer circumferential surface facing the annular shoulder surface that serves as the seat surface of the valve spring is tapered, and the stem free end side edge of the through hole through which the valve stem passes is rounded, thereby further improving the rigidity of the retainer. Furthermore, the lubricating oil can be suitably sprayed over the entire retainer, and thermal deformation thereof can be suppressed.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, a pair of intake valves 1.2 are installed in the internal combustion engine main body (not shown). Both intake valves 1.2 are connected to the crankshaft ( A pair of low-speed cams 4.6 and a single high-speed cam 5, each having a roughly egg-shaped cross section, are integrally provided on a camshaft 3 that is synchronously driven at 1/2 speed (not shown). Cam 4-6
The first to third transmitting members engage with each other to perform rocking motion.
The opening/closing operation is performed by working with the zero tension arms 7 to 9. Additionally, this internal combustion engine is equipped with a pair of exhaust valves (not shown), which are driven to open and close in substantially the same configuration as the above-mentioned intake valve 1.2, but below, only the intake valve side will be described. explain.

The first to thirtieth lever arms 7 to 9 are connected to a rocker shaft 10 fixedly installed below the camshaft 3 in parallel with the shaft.
are pivotally supported adjacent to each other so as to be able to swing freely. Of these, the first and thirtieth lever arms 7.9 have basically the same shape, their bases are pivotally supported by the rocker shaft 10, and their free ends extend above both intake valves 1.2. It's out. Tappet screws abutting the upper ends of the respective intake valves 1.2 are screwed into the free ends of the double-ended hook arms 7.9 so as to be movable forward and backward, and are prevented from loosening by lock nuts.

The 20th claw arm 8 is connected to the first and 30th claw arms 7.
It is pivotally supported by a rocker shaft 10 between 9 and 9. This second
The zero tension arm 8 slightly extends from the rocker shaft 10 toward the middle of both intake valves 1.2, and the upper end surface of a lifter (not shown) comes into contact with the cam slipper 8a on the upper surface of the 20th tension arm 8. The rocker arm is resiliently biased so as to be in constant sliding contact with the rocker arm 5.

As described above, the camshaft 3 is rotatably supported above the engine body, and the low-speed cam 4.6 and the high-speed cam 5 are integrally connected. Low speed cam 4.6
is formed in a cam profile suitable for the low speed rotation range of the engine, and is configured such that its outer peripheral surface can slide into cam slippers 7a and 9a formed on the upper surfaces of the first and thirtieth lever arms 7.9, respectively. has been done. Further, the high-speed cam 5 is formed to have a cam profile suitable for the high-speed rotation range of the engine.

Each of the rocker arms 7 to 9 is in a state where it can swing in one direction and a state where it can be relatively displaced by a connecting device 14 installed in a hole drilled through the center thereof and parallel to the rocker shaft 10. and can be selectively switched.

On the other hand, each valve stem 1a, 2 of each intake valve 1.2
Valve spring retainers 15.16 are provided at the proximal end portion via cotters, and at the same time, each valve stem 1 is provided between these retainers 15.16 and the engine body.
a pair of valve springs 17, each surrounding the valve springs 17.a and 2a.
18 is wrapped around each intake valve 1.
2 is always resiliently biased in the valve closing direction, that is, upward in FIG.

Here, the valve spring retainer 15.16 is made of 14.5 wt% silicon, 2°2 wt% copper, and
3. Hard particles produced by producing atomized powder containing 0.7 wt% magnesium, 4.2 wt% iron, and 2.1 wt% manganese, and mixing this with alumina, silica, and titanium oxide.
Qwt% is added, pressed into powder, sintered into a cylindrical shape by hot extrusion, cut into a disk shape, and then forged.

Since both valve spring retainers 15, 16 have similar structures, only one retainer 15 will be described below with reference to FIGS. 3 and 4. This retainer 1
5 has a tapered central through hole 20 through which the valve stem 1a passes through the socket (taper angle 20°).
. Further, on the outer peripheral surface of the retainer 15, a first annular shoulder surface 21 is provided as a spring seat for holding the outer valve spring 17, and a second annular shoulder surface is provided as a spring seat for holding the inner valve spring 18. It has a surface 22.

Here, the axial length L2 from the free end of the valve stem 1a of the retainer 15, that is, from the upper end surface 23a shown in FIG. It is longer than half of the direction length Ll. Further, the axial length L3 from the first annular shoulder surface 21 to the second annular shoulder surface 22 is equal to the axial length L4 from the lower end surface 23a to the first annular shoulder surface 21 and the second annular shoulder surface 22.
It is longer than the distance L5 from the annular shoulder surface 22 to the lower end surface 23b. In this example, Ll is 8.8M, L
2 is 6.0mm, 13 is 3.8#, L4 is 2.2M, [
5 is 2.8#, the outer diameter of the upper end surface 23a is 28.0 m, the outer diameter of the lower end surface 23b is 15.4 inches, and the second annular shoulder surface 2
The outer diameter of 2 is 21.7m.

On the other hand, the outer peripheral surface portions 24.25 adjacent to each annular shoulder surface 21.22 and facing each annular shoulder surface from the inside gradually extend from the lower end surface 23a side toward the lower end surface 23b side along the axial direction. It has a tapered shape that reduces in diameter (each taper angle 5
°). Therefore, not only the continuity of the internal crystal is improved compared to the case where each outer circumferential surface is orthogonal to each annular shoulder surface, but also the lubricating oil flying from the free end side of the valve stem 1a is easily sprayed. This also has the effect of suppressing thermal deformation of the retainer 15. Furthermore, it is also possible to prevent each valve spring 17.18 from coming into contact with the outer circumferential surface portion 24.25.

On the other hand, as shown in FIG. 4, which shows a further enlarged view of the retainer 15, the lower end surface 2 of the through hole 20 in the retainer 15
The edge 26 on the third side is rounded with a radius of curvature of 1.5 mm by machining. Therefore, unlike the case where the edge is simply chamfered, no burrs remain or stress is concentrated on the edge. In fact, the radius of curvature of the edge 26 is 0.
It is sufficient if it is 5 mm or more.

[Effects of the Invention] As described above, according to the present invention, the intermediate portion of the valve spring retainer can be made thicker by simply changing the positions of the respective annular shoulder surfaces serving as spring seats of the outer and inner valve springs along the axial direction. Improves overall rigidity. In addition, the rigidity of the retainer is further improved by tapering the outer circumferential surface facing the annular shoulder surface that serves as the seat surface of the valve spring, and by rounding the free end side edge of the through hole through which the valve stem passes. Furthermore, the lubricating oil can be suitably sprayed over the entire retainer, and thermal deformation thereof can be suitably suppressed. From the above, the effects of the present invention are extremely large.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing a valve mechanism of an automobile engine using a camshaft according to the present invention. FIG. 2 is a side view showing the valve mechanism with a portion cut away, similar to FIG. 1. FIG. 3 is a longitudinal sectional view showing only the valve spring retainer. FIG. 4 is an enlarged view of the main part of FIG. 3. 1.2...Intake valve ``la, 2a...Valve stem 3...Camshaft 4.6...Low speed cam 5...High speed cam 7...10th lever arm 8
...20th Tsuka Arm 9...30th Tsuka Arm 7a
, 8a, 9a... cam slipper 10... rocker shaft 11... cylinder head 1
4... Connecting device 15.16... Retainer 17
．． 18... Valve spring 20... Through hole 21.22... Annular shoulder surface 2
3a, 23b... End surface 24.25... Outer peripheral surface portion 26
... Edge patent applicant Honda Motor Co., Ltd.
Patent Attorney Yo Oshima - Figure 4

Claims (3)

[Claims] (1) An aluminum alloy is attached to the base end of the valve stem via a cotter to hold a pair of valve springs coaxially wound on the inside and outside of each valve stem of an engine intake and exhaust valve. A forged valve spring retainer comprising: a tapered central through hole into which the cotter is fitted; a first annular shoulder surface formed on the outer periphery as a spring seat for the outer valve spring; a second annular shoulder surface formed as a spring seat closer to the free end of the valve stem along the axial direction than the first annular shoulder surface; the axial length from the first annular shoulder surface to the second annular shoulder surface is longer than half the axial length from the one end surface to the other end surface, and from the first annular shoulder surface to the second annular shoulder surface; The axial length to the surface is longer than the axial length from the one end surface to the first annular shoulder surface and the axial length from the second annular shoulder surface to the other end surface. Valve spring retainer. (2) Each outer circumferential surface portion facing each of the annular shoulder surfaces from inside has a tapered shape whose diameter gradually decreases from the one end surface side toward the other end surface side along the axial direction. A valve spring retainer according to claim 1. (3) The valve spring retainer according to claim 1 or 2, wherein an edge of the central through hole on the other end surface side is rounded.