Patent Publication Number: US-4483281-A

Title: Poppet valve spring retainer with integral hydraulic tappet

Description:
This application is a continuation of my previously filed application for a Poppet Valve Spring Retainer with Integral Hydraulic Tappet, Ser. No. 356,782, filed 03/10/82, now abandoned which application is a divisional application of my previously filed application for Poppet Valve Spring Retainer with Integral Mechanical Adjustable Tappet, Ser. No. 055,951 filed 07/09/79 which is now U.S. Pat. No. 4,321,894 issued on 03/30/82. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The device of this invention resides in the area of valve adjustment means for internal combustion engines having overhead cams or rocker arms and more particularly relates to a valve spring retainer including hydraulic means for adjustment of the gap between the cam shaft and/or rocker arm and valve stem. 
     2. History of the Prior Art 
     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 rocker 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. Adjustment means are provided to change this gap. Although such changes are made relatively simple by hydraulic valve lifters, in many instances there is a penalty paid in increased weight as well as decreased efficiency and reliability of the hydraulic lifter. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide an hydraulic lifter that would have application to both overhead cams and rocker arms thus standardizing the lifter structure. 
     It is an object of this invention to provide a simplified light-weight hydraulic lifter for the adjustment of the gap between a valve stem and rocker arm which is significantly less bulky than the hydraulic lifters of the prior art. 
     It is a further object that the valve spring&#39;s resistance to compression not be transferred directly to the top of the valve stem as presently done in the prior art. 
     The device of the present invention is comprised of a valve spring retainer base which is adapted to fit over the valve spring and has an bore 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. A cap member is also provided adapted to be engaged into the valve spring retainer base. 
     Since no adjustments are needed in hydraulic lifters as are needed in mechanical lifters, no adjustably rotating threaded parts are needed between the cap member and the valve spring retainer base. A chamber is provided within the cap member which, when positioned within the valve spring retainer base, is held in position by a semicircular circlip which fits within a groove provided in the upper outer portion of the valve spring retainer base. An hydraulic plunger is positioned above a valve stem seal member and has provided therebetween a preloaded spring and ball combination for the capture of hydraulic fluid therein upon the downward thrust of the cam or the rocker arm. The plunger may be hollowed in its upper portion and have an aperture in its bottom aligned with the ball. The ball operates as an hydraulic valve for the plunger, the plunger being just above the ball, riding in the bore just above the pressure chamber. When the cap member is depressed, it moves the plunger inward toward the center of its chamber, thereby compressing oil within the pressure chamber which action provides the means for transferring the movement of the cap member to the valve spring retainer base due to the minimal compressibility of the oil therein. Upon this increase of pressure on the device of this invention, some oil will leak backwards out of the pressure chamber formed by the plunger and corresponding hollow in the valve spring retainer past the wall of the plunger. Oil flow is controlled by the ball which closes off the oil return to the reservoir under pressure while at times when there is no force thereupon, the hole allows oil to enter the pressure chamber beneath the ball. This design has advantages over the current art which incorporates an hydraulic lifter within a separate housing bored into the top of the cylinder head. This invention is held in position by the key on the valve stem and the pressure of the valve spring upwards against the valve spring retainer base. This design simplifies substantially the construction of hydraulic lifters and lessens significantly their weight. A valve stem bushing acts as a seal member in this embodiment and prevents the escape of oil fluid from the pressure chamber down along the valve stem. In some embodiments the valve stem seal member can be threaded into its position to prevent its movement out of its seat or sealed in position by an O-ring or an inserted cup. In this embodiment a hole can be provided within the cap member periphery and/or the valve spring retainer base in the midsection which would allow oil to enter therein and which would lessen the noise from resonance and act as an additional reservoir of oil from which the pressure chamber would draw for its proper operation. It should be noted that in this embodiment this is an additional reservoir if the motor should run low on oil, oil would still be provided within the pressure chamber due to its being trapped between the valve spring retainer base and the cap member. 
     An alternate embodiment of this invention utilizes a hardened steel upper cap member with a lower cap member made of lightweight material having a reservoir defined therein. Below the reservoir is a hardened steel cup member with an aperture defined therein. No seal member is used, but a second hardened steel cup member is placed in the valve spring retainer base and contains a hollow piston member. Within the upwardly facing hollow is the spring cap and ball which control entry of fluid from the reservoir. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective cross-sectional view of the device of this invention utilizing hydraulic lifters. 
     FIG. 2 is an alternate embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Seen in FIG. 1 is valve spring retainer base 60 with a central portion 62 and an outer portion 64. Retainer cap 66 is positioned within the valve spring retainer base and is held in place by retainer circlip 68 which fits within groove 70 within the valve spring retainer base 60. In a first embodiment a valve stem seal member 72 is located at position 74 above the valve stem receipt bore 76 above which is positioned plunger 78 which rides within pressure chamber 80 formed by projections 82 extending from valve spring retainer base 60. Below the plunger is located ball member 84 and cup 86 with spring member 88 positioned therebelow. At least one aperture 90 can be provided to allow for the entrance of oil into reservoir 81 for the hydraulic action as described above and one or more apertures 92 may be positioned within the valve spring retainer base 60 or such as 93 in cap 66 to allow for the entrance of oil therein. 
     Illustrated in FIG. 2 is the second embodiment of this invention utilizing hardened cap 91 above lower cap 92 which has a reservoir 94 defined therein with oil entrance aperture 96 to allow oil into the reservoir. No seal member is used and this embodiment has an upper hardened steel cap 100 with an aperture defined therein positioned below the reservoir and a lower hardened bushing/seal member 102 positioned above the valve stem receipt bore 101. Within cap 102 is hollow plunger 104. Within the upward-facing hollow portion is ball 108 aligned with the aperture in the upper cap 100. Below ball 108 is cup 110 and spring 112 which extends to the inside hollow of plunger 104. 
     It should be noted that the valve spring retainer base and seal member can be constructed of aluminum or other lightweight 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. 
     It should be further noted that there are many advantages to the utilization of the valve spring retainers of this invention besides their being compact and lighter in weight than the structures that accomplish similar functions in the prior art. 
     In the situation where the seal member is of a predetermined strength, the valve stem retainer of 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 seal member dissipates the destructive force, minimizing damage to the valve so that repairs may be made easily to the device of 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 principles and spirit of the invention.