EP0090105B1

EP0090105B1 - Adjustable valve spring retainer for internal combustion engine

Info

Publication number: EP0090105B1
Application number: EP82301647A
Authority: EP
Inventors: Alfred Anthony Black
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-03-29
Filing date: 1982-03-29
Publication date: 1989-12-20
Also published as: EP0090105A1; DE3280067D1; EP0375792B1; EP0375792A1

Description

This invention relates to valve adjustment means for internal combustion engines having overhead cams or rocker arms and more particularly relates to a valve spring retainer including means for adjustment of the gap between the cam shaft and/or rocker arm and valve stem.
In typical overhead cam engines the valves are operated by a rocker arm pushing on the valve stem or cam shaft pushing on bucket tappets. The rocket arm is usually actuated by a cam located in association therewith. In order to provide for the thermal expansion of the valve stem due to the heat created by the fuel combustion within the engine, gaps are usually provided between the valve stem and rocker arm. Most adjustments of the gap mentioned above are accomplished by means of a locked screw or the use of shims placed within the bucket member positioned over the valve spring retainer. Althgugh such adjustments are relatively simple, in many instances one must remove the cam shaft from the vehicle in order to place the shims in position under the bucket. In other systems the bucket may be adjusted by providing a tapered screw member threaded across the top of the valve stem at an angle so that if it is rotated upward it raises the bucket or if it is rotated downward it lower the bucket. A gap adjustment device that is pertinent to the device of this invention is disclosed in U.S. Patent No. 2,722,204, issued to Adolph Wente entitled "Means for Adjusting the Lost Motion of the Valve Actuation in Internal Combustion Engines." This system provides adjusting means that utilize a threaded valve stem on which a nut-like member is rotatably threaded. Systems such as this must provide means to prevent rotation of the valve stem when the nut is rotated thereon or adjustment. US Patent No. US-1857005 discloses a mechanically adjustable valve mechanism for an I.C. engine, and Swiss Patent No. CH-A-322762 discloses an hydraulic arrangement. Neither of these last two disclosures is considered to provide a wholly appropriate adjustment solution.
It is desirable to provide a device for the adjustment of the gap between a valve stem and rocker arm wnich is substantially lighter in weight to that used in the present art, which is significantly less bulky, which replaces three to four elements now utilized to accomplish the same adjustment, and which removes the point of direct actuation of the valve stem from its top thereby lessening the stress on such stem and allowing it to be lighter in weight. It is also desirable that the valve spring's resistance to compression not be transferred directly to the top of the valve stem as present done in the prior art.
According to this invention there is provided an adjustor for the adjustment of the thermal expansion gap between a valve stem and its operation means within an internal combustion engine having a valve spring retainer member with a valve stem receipt aperture therein at one end, said valve spring retainer member being removably retained upon said valve stem by a keeper key, characterised by a cap member located to the other end of said valve spring retainer member and adjustably connected thereto, and means to permit an adjustment of either (a) a first gap between said cap member and said operation means and, as a result, corresponding inverse adjustment of a second gap between said cap member and said valve stem, or (b) said second gap and, as a result, corresponding inverse adjustment of said first gap, said adjustment means including means to raise or lower said cap member in relation to said valve spring retainer member said cap member being arranged neither to be directly attached to said valve stem in normal operation nor to have direct contact with said valve stem.
In a preferred embodiment of the present invention the device comprises a valve spring retainer base which is adapted to fit over the valve spring and has an aperture through a central portion thereof for receipt of the valve stem, and lip means for the engagement of an outer and inner valve spring if such is used in the engine. The valve spring retainer base further has a central portion threaded on its inside and an upwardly extending outer portion threaded along its inside. The outer valve spring lip member located below the outer threaded portion of the valve spring retainer base projects downward to fit over, engage, and retain the valve's outer spring. At a position along the periphery of the upper portion of the outer section of the valve spring retainer base is a lock bolt receipt aperture whose function will be described below. A valve adjustor cap is also provided having on its bottom a central projection with threads upon the outer portion thereof adapted to be threadedly engaged into the inner threaded portion of the valve spring retainer base. The valve adjustor cap has along its outer periphery a threaded portion adapted to engage into the outer threaded portion of the valve spring retainer base. The top of the valve adjustor cap has a section thereon which is polygonal, e.g., hexagonal, and is adapted to be engaged for the rotation by a wrench above the valve spring retainer base. A lock bolt is provided along with a cap lock member having an aperture therein through which the lock bolt may pass. The cap lock member has a lip member adapted to engage into a selected one of a plurality of apertures disposed around the periphery of the valve adjustor cap so that when the valve adjustor cap is rotated within the valve spring retainer base to its desired height for the adjustment of the gap between the valve stem and the rocker arm, it may be locked into position by the placement of the cap lock member with the lip or lips thereof engaged into the nearest of the apertures within the valve adjustor cap. The lock bolt is then passed through the aperture within the cap lock member and passed into the lock bolt receipt aperture in the valve spring retainer base and is affixed into position by a nut threaded on its extending portion. Within the central portion of the projection centrally located on the underside of the valve adjustor cap is defined an area adapted for receipt of a valve stem spring member which fits therein and a valve stem bushing. The valve stem bushing has a projection upon one side thereof which engages the valve stem spring member. The valve stem bushing is adapted to fit into the valve stem bushing receipt area defined within the valve spring retainer base. The valve stem receipt aperture defined in the valve spring retainer base is constructed somewhat more narrowly at its base then at its top. When the valve stem is positioned therein, a valve keeper key is placed within a groove in the top of the valve stem which is then adapted to move freely in the top of the valve stem receipt aperture but not pass downward out of the valve stem receipt aperture due to the fact that the base of the valve stem receipt aperture is narrower than the valve keeper key positioned on the valve stem. When positioned on the valve stem, this key retains the structure of this embodiment in place on top of the valve stem, and the valve spring is compressed keeping the valve in an upward position closing its associated port. When the top of the valve adjustor cap is struck by the cam directly or in some cases by the rocker arm, the valve's port will be opened.
It has been found preferable to have the valve adjustor cap supported at both its center and its periphery rather than merely at one or the other position to prevent deformation at its centre and to help distribute the force load more evenly over the top surface of the valve adjustor cap. It is possible that in the operation of this device, the valve stem can rotate to various positions during use which rotation assists in the distribution of the wear on the valve's head/seat interface. To prevent any difficulty in threading the valve adjustor cap into the valve spring retainer base due to unmatched threads between the inner and outer threads, one may in an additional embodiment have the valve adjustor cap constructed of two pieces, one being the outer threaded ring with a lip for the support of the outer portion of the inner cap. This outer threaded ring can have a plurality of projections extending from its top so that when the cap is threaded into the central thread of the valve adjustor base, these projections can be grasped by a tool and the outer threaded ring rotated to raise its lip to support the periphery of the valve cap. The valve adjustor cap may also have an insert aperture defined therein to receive a polygonal hardened insert if the valve cap and valve spring retainer base are to be constructed of aluminium or other light material which might wear too easily from the action of the rocker arm or cam.
The spring-loaded bushing is provided to help keep the valve in place when the device of this embodiment is depressed. It further assures that the valve stem will move downward at the same time or at an extremely short time after the device of this embodiment has started its downward movement. It still further allows for the possibility of expansion of the valve stem therein especially when the retainer adjustor is adjusted for a zero gap. Further, it helps eliminate a certain amount of the noise caused by the valve stem striking directly against the valve adjustor cap. It also keeps pressure on the valve stem even when the device of this embodiment is depressed to prevent or minimize any upward movement of the valve stem on its own as the depressing force of the valve cap is not focused directly upon the stem of the valve but it is on the valve spring.
In some embodiments a circlip may be used in place of this spring if the expansion gap is made between the cap and its operation means.
In some embodiments there may be provided one or more holes drilled within the valve spring retainer base as well as the cap that would allow oil to circulate within the chamber formed between the valve spring retainer base and the valve adjustor cap. The oil circulating through these holes will provide lubrication within the chamber and will also assist in decreasing noise by filling the relatively open chamber in which there might tend to be certain resonances. This embodiment will also assist in keeping the valve spring retainer base and valve adjustor cap cooler so that heat from cam friction and heat transferred from the valve head through the valve stem to this embodiment would not cause significant expansion thereof.
By way of non-limiting example, embodiments of this invention will now be described in greater detail with reference to the accomanying drawings of which:-

Figure 1 is a perspective cross-sectional view of an exemplary device according to this invention incorporating mechanical lifters;
Figure 2 is a perspective cross-sectional view of an embodiment having a solid cap;
Figure 3 is a perspective cross-sectional view of an embodiment having a round centrally threaded cap; and
Figure 4 is a cross-sectional view of an embodiment having a peripherally threaded cap.

In the device of Figure 1, a valve spring retainer base 10 has on its bottom portion a protruding outer valve spring retaining lip 12 into which is engaged outer valve spring 20. Also seen in this view are inner valve spring lip 14 into which is engaged inner valve spring 18, and valve stem receipt aperture 16 into which the valve stem passes. Aperture 16 is somewhat narrower at its base than at its top and acts to engage the valve stem due to a keeper key inserted into a groove at the top of the valve stem. Seen in a central portion of the valve spring retainer retainer base 10 is valve stem bushing receipt ledge 52. Projection 21 is centrally positioned above the valve stem receipt aperture and has a threaded portion 22 along its insides. Valve spring retainer base 10 has an upwardly extending portion 23 along its periphery having along the inside thereof an inner threaded portion 24. Seen threaded into valve spring retainer base 10 is valve adjustor cap 26 which has positioned on its top a hexagonal member 32 for easy rotation thereof as mentioned below in relation to the valve spring retainer base 10. Such hexagonal member 32 may be constructed as an insert into a cap receipt aperture 33. A central portion 27 of the valve adjustor cap 26 protrudes downward and is externally threaded to engage the central threaded portion 22 of the valve spring retainer base 10. The outer portions 30 of valve adjustor cap 26 can also be threaded to engage into, and adjust in an upward and downward fashion as it is rotated within, the valve spring retainer base 10. The valve adjustor cap can be constructed having a separate outer threaded ring portion 35 having a lip 37 adapted so that the valve adjustor cap may be supported by the lip around the cap's periphery. A plurality of adjustment projections 39 extend from the threaded ring portion so that when the cap is centrally threaded, the threaded ring portion 35 can be backed up to it by grasping and rotating such adjustment projections by a tool designed to engage them. Also seen in this view is a lock bolt receipt aperture 34 defined within the valve spring retainer base 10. The cap lock member is positioned within selected ones of the plurality of cap lock member holes 40 seen within the valve adjustor cap. A valve stem bushing 36 is provided and adapted to rest upon its ledge 52 within the valve spring retainer base, and a spring member 45 is provided to engage both a protruding portion 47 of the valve stem bushing 46 and a projection 42 thereabove on the valve adjustor cap to keep pressure on the valve stem as described above. A plurality of apertures 50 may be provided within the valve spring retainer base and adjustor cap member to allow for the flow of oil therethrough.
Figure 2 illustrates another alternate embodiment of the device of this invention having the cap member 26 constructed of a solid piece. It should be noted that the valve spring retainer base can be constructed of aluminium or other light weight material and the cap member may be made of the same material or of a harder steel-like material as mentioned above to resist wear.
Figure 3 illustrates a further alternate embodiment having a cap member with a round top 300 having apertures 302 defined therein for receipt of projections on a tool for the rotation thereof. In this embodiment only the central portion 304 of the engagement between the cap and the valve spring retainer base is threaded and there are no threads or other engagement means at the peripheral areas 306.
Figure 4 illustrates still yet another embodiment having the cap member only peripherally threaded. This embodiment is especially useful for smaller retainer members. The cross-section view of Fig. 4 illustrates the tapered form of the valve stem receipt aperture or bore which accommodates the above-mentioned keeper key that is inserted into a groove at the top of the valve stem. To facilitate illustration in perspective this tapered form of the valve stem receipt aperture or bore has been shown as a simple cylinder in Figs 1, 2 and 3 although in reality it conforms to the tapered shape of Fig 4.
It should be noted that there are many advantages to the utilization of adjustable valve spring retainers embodying this invention beside their being compact and lighter in weight than the structures that accomplish similar functions in the prior art. One advantage is that the valve spring retainer cap can be set at the required gap or at a zero lash than is now possible with present gap- adjusting devices without the significant problem of the valve head being forced into the valve chamber upon the thermal expansion of the valve stem. The gap above the bushing allows the stem to expand therein by upward movement thereof. Since the bushing in the mechanical embodiment herein is not necessarily retained rigidly in place, it can allow the valve stem to move somewhat into the valve stem retainer. This movement would also allow combustion chamber pressure to assist in closing the valve where such pressure would push the valve upwards only against the weaker pressure of the valve bushing spring which would seal the combustion chamber. In the situation where the bushing is constructed of a material of predetermined strength and the bore in which it rests is of the same dimensions as the valve stem receipt bore, the valve stem retainer embodying this invention will advantageously provide a place of movement by its deformation when struck by the valve stem in situations where the engine is over-revved and the valve head is hit by the piston. This destruction or deformation of the bushing dissipates the destructive force, minimizing damage to the valve so that repairs may be made easily to the device embodying this invention without having to pull the head off the engine to reach a damaged valve.
Although the present invention has been described with reference to particular embodiments, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the scope of the invention claimed.

Claims

1. An adjustor for the adjustment of the thermal expansion gap between a valve stem and its operation means within an internal combustion engine having a valve spring retainer member (10) with a valve stem receipt aperture (16) therein at one end, said valve spring retainer member being removably retained upon said valve stem by a keeper key, characterised by a cap member (26; 300) located to the other end of said valve spring retainer member (10) and adjustably connected thereto, and means (32, 26, 27) to permit an adjustment of either (a) a first gap between said cap member (26; 300) and said operation means and, as a result, corresponding inverse adjustment of a second gap between said cap member (26; 300) and said valve stem, or (b) said second gap and, as a result, corresponding inverse adjustment of said first gap, said adjustment means (32, 26, 27) including means (32) to raise or lower said cap member (26; 300) in relation to said valve spring retainer member (10) said cap member (26; 300) being arranged neither to be directly attached to said valve stem in normal operation nor to have direct contact with said valve stem.

2. An adjustor according to Claim 1 characterised by lip means (12, 14) defined on said valve spring retainer member (10) for lateral retention of said valve spring (18, 20).

3. An adjustor according to Claim 1 or Claim 2, characterised by locking means (34, 36, 38, 40) to retain said cap member (26; 300) in a selected position in relation to said valve spring retainer member (10).

4. An adjustor according to Claim 3, characterised in that a plurality of apertures (40; 302) are defined within the outer periphery of te top surface of said cap member (26; 200; 300), said locking means (34, 36, 38, 40) being adapted to engage into selected ones of said apertures (40; 302) to lock said cap members (26; 200; 300) into position to prevent rotation of same within said valve spring retainer member (10).

5. An adjustor according to any preceding claim characterised by means (46) for limiting movement of said valve stem through said valve stem receipt aperture (16).

6. An adjustor according to Claim 5, wherein said movement limiting means (46) is characterised by means to allow the thermal expansion and reciprocating movement of said valve stem within said valve stem receipt aperture (16).

7. An adjustor according to Claim 5 or Claim 6, characterised in that said movement limiting means comprises a bushing (46) to limit said movement when the bushing is contacted by said cap member (26; 200; 300) and also to limit inward movement of said cap member (26; 200; 300) during adjustment of said cap member.

8. An adjustor according to Claim 1, characterised by including:

lip means (14) incorporated into said valve spring retainer member (10) for retention of an inner valve spring member (18);

an outer upwardly extended internally threaded portion (23) incorporated in said valve spring retainer member (10);

a central upwardly extended internally threaded portion (22) incorporated in said valve spring retainer member (10), the inner portion of which defines a bushing ledge (52);

a bushing member (46) having a central projection (47) defined on an upper side, said bushing (46) being positioned on said bushing ledge (52);

a lock bolt receipt aperture (34) defined within the periphery of said upwardly extending outer portion (23) of said valve spring retainer member (10); and

a spring member (45) positioned between said bushing member (46) and said valve adjustor cap member (26), said cap member including means (24, 30; 22, 27) for engagement of said valve spring retainer (10) and adapted to allow the upward and downward adjustment of said valve adjustor cap (26) within said valve spring retainer member (10).

9. An adjustor according to Claim 8, wherein said valve adjustor cap member (26) is characterised by a threaded outer portion (30) and a threaded central projection (27), both adapted to engage the threaded portions (24, 22) of said valve spring retainer member (10).

10. An adjustor according to Claim 9, characterised in that said valve adjustor cap member (26) comprises an outer threaded ring member (35) adapted threadedly to engage the outer threaded portion (24) of said valve spring retainer member (10) having a lip (37) around its inside circumference, said cap member (26) having an inner threaded portion (27) adapted to engage the central threaded portion (22) of the valve spring retainer member (10), and the outer periphery of which is adapted to rest upon said lip (37), and in that means are provided to rotate said threaded ring member (35) independently of said valve adjustor cap member (26).

11. An adjustor according to any one of Claims 8 to 10, characterised in that a manipulatable projection (32) is located within a central portion of said valve adjustor cap member (26) for facilitating rotation of said valve adjustor cap member within said valve spring retainer member (10).

12. An adjustor according to Claim 11 characterised in that said projection (32) is a member insertable within an aperture in the upper surface of said valve adjustor cap member (26).