Hydraulic tappet oil metering means
United States Patent [1 1 Barnes 51 Apr. 15, 1975 1 1 HYDRAULIC TAPPET OIL METERING MEANS i 21 Appl. No.: 416,940  
 [52] US. Cl. 123/90.35; 123/9046; 123/9055;  
  137/433 [51] Int. Cl. F0lm 1/06 [58] Field of Search 123/9035, 90.46, 90.55, 123/9056, 90.57; 137/202, 433  
 [56] References Cited UNITED STATES PATENTS 2,356,900 8/1944 Voorhies 123/9056 2,434,386 1/1948 Bradshaw 123/9046 2,818,050 12/1957 Papenguth 123/9035 2,840,063 6/1958 Purchas 123/9055 3,029,832 4/1962 Tischler 137/433 3,054,392 9/1962 Thompson.... 123/9035 3,194,439 7/1965 Bcduerftig 137/433 3,273,514 9/1966 Bender 137/433 3,379,180 4/1968 Kabel 123/9035 7/1969 Stork 137/433 3,490,423 1/1970 Shunta.... 123/9055 3,528,451 9/1970 Hansen 137/433 3,662,725 5/1972 Dragon 137/202 3,665,156 5/1972 Lee 137/202 3,799,186 3/1974 Bulin 137/433 FOREIGN PATENTS OR APPLICATIONS 1,051,998 11/1966 United Kingdom 123/9035 903,983 8/1962 United Kingdom 123/9055 Primary Examiner-Manuel A. Antonakas Assistant Examiner-Danie1 J. OConnor Attorney, Agent, or Firm1(inzer, Plyer, Dorn &amp; McEachran [57] ABSTRACT 6 Claims, 2 Drawing Figures HYDRAULIC TAPPET OIL METERING MEANS SUMMARY OF THE INVENTION The present invention relates to improvements in hydraulic tappets and in particular to an improved metering element for use therein.  
  A primary purpose is a hydraulic tappet of the type described having a floating metering element within the pressurized oil chamber.  
  Another purpose is a hydraulic tappet of the type described in which a spherical ball having a specific gravity less than that of the oil within the chamber is used to provide the metering means from the pressurized oil chamber.  
  Other purposes will appear in the ensuing specification, drawings and claims.  
 BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated diagrammatically in the following drawings wherein:  
  FIG. 1 is an axial section through a hydraulic tappet, and  
 FIG. 2 is a bottom view of the plunger cap.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT A generally cylindrical tappet body is indicated at and may have an interior bore 12 terminating in an open end 14. Positioned within the bore 14 is a plunger 16 having a plunger cap 18. Within the plunger is a pressurized oil chamber 20. The plunger reciprocates relative to the tappet body and is held within the bore 12 by means of a snap ring or the like 22 positioned within a groove 24 adjacent the open end 14.  
  A plunger return spring 26 is seated upon a surface 28 formed at the closed end of the bore 12 and bears against a portion of a retainer 30 which, through a small spring 32, holds a valve element 34 against the open end 36 of the plunger 16. The above-described construction may be conventional and is generally shown in my prior US. Pat. No. 3,430,613.  
  The exterior of the tappet body 10 may have a groove 38 which, through a passage 40, communicates with a groove 42 on the interior surface of the tappet body. A mating groove 44 is formed on the exterior of the plunger and communicates with the pressurized oil chamber through a passage 46. Thus, oil passage means are formed between the exterior of the tappet body and the interior of the tappet plunger to pass oil from the engine oil gallery to chamber 20. The abovedescribed structure is conventional in hydraulic tappets.  
  Positioned within the chamber 20 is a floating metering element 48, having a specific gravity less than that of the oil which is normally within the chamber 20, and which will flow through the chamber as a part of the normal operation of the tappet. The lower surface of cap 18 may be conical, as indicated at 50, so that the ball 48 may be substantially in mating sealing contact therewith. A groove 52 is formed in surface 50, as shown particularly in FIG. 2. The groove is in communication with the chamber 20 and with a plunger cap oil orifice 54 which is in communication with a rounded surface or socket S6 at the top of the plunger cap 18. Normally, a portion of the engine push rod will be seated within the socket 56 and thus oil passing through the orifice 54 will be effective to lubricate the push rod and through it the rocker arm.  
  The tappet will generally function in the conventional manner. The plunger will receive oil from the body through the grooves and passages to fill and pressurize chamber 20. The oil within chamber 20 will cause the ball 48 to float upon its upper surface and be maintained in contact with the mating sealing surface 50 at all times during operation of the tappet. Oil will be provided at orifice 54 to lubricate the push rod and rocker arm through groove 52, the cross section of which can be closely controlled to provide exact metering of the oil. Thus, ball 48, having a specific gravity less than that of the oil, will float upon the oil within the chamber and the level of the oil within the chamber will be such that the ball will always be in contact with conical surface 50, thus forming a seal about the orifice 54, except for groove 52.  
  The invention should not be limited to a spherical member as the floating metering element. Other shapes may be equally satisfactory. However, with a spherical member, i.e., a ball, the surface 50 will generally be conical. What is important is to provide a floating element, which can seal against a mating surface, except for a defined passageway, the groove 52 as shown in the drawing.  
  The ball may be formed of a suitable plastic, and it may be either hollow or solid, depending upon the specific gravity of the plastic. The material forming the ball must be such that it can easily withstand the normal engine oil temperatures and pressures without deforming and/or disintegrating.  
  Although the application has been described in connection with hydraulic tappets, it should be obvious that the oil metering method shown is equally applicable to mechanical tappets.  
  In addition, the invention should not be limited to the particular manner shown for providing an oil groove on the undersurface of the plunger cap. Other means may be equally satisfactory for providing an oil passage between the floating metering element and the undersurface of the plunger cap.  
  Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions and alterations thereto.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
  1. In a tappet, a tappet body having a bore therein, a hollow plunger reciprocally mounted in said body bore, an oil chamber within said hollow plunger, cooperating oil passage means between the exterior of said body and said oil chamber, spring means positioned in said bore normally urging said plunger outwardly therefrom,  
 said plunger having a plunger cap and an oil orifice in said plunger cap communicating with said chamher, and a floating totally unconfined metering element in said chamber, the specific gravity of the floating metering element being less than the spe cific gravity of oil, cooperating metering means on said element and plunger cap for controlling the flow of oil through said orifice.  
  2. The structure of claim 1 further characterized in that the inner surface of said plunger cap and said floating metering element have cooperating surfaces,  
 formed to effect a seal therebetween except for a predetermined defined area.  
  3. The structure of claim 2 further characterized in that said predetermined defined area is formed by a groove in the inner surface of said cap.  
  4. The structure of claim 3 further characterized in that said metering element is generally spherical in shape.  
 5. The structure of claim 4 further characterized in that the inner surface of said cap facing said metering element is generally conical in configuration.  
 plunger cap surface.