US2931347A - Variable valve lifter for internal combustion engines - Google Patents

Description

April 1960 N. WILLIAMS 2,931,347

VARIABLE VALVE LIFTER FOR INTERNAL COMBUSTION ENGINES Filed April 10. 1958 I N V EN TOR. A/ED l. WILLIAMS.

ATTORNEY ilnited States Patetitf) VARIABLE VALVE LIFTER FOR INTERNAL COMBUSTION ENGINES Ned L. Williams, Mesa, Ariz. Application April 10, 1958, Serial No. 727,633

6 Claims. (Cl. 123- 90) This invention pertains to improvements in variable valve lifter mechanism for internal combustion engines.

One of the objects of this invention is to provide a hydraulically operated tappet mechanism for selfadjusting and compensating type operable to vary the performance characteristics of the engine under various speeds of operation.

Another object is to provide an automatic hydraulic valve tappet mechanism to vary the timing of valve opening and closing of the engine for various operating speeds so as to provide better performance and operating economy throughout the entire operating speed range of the engme.

Still another object of this invention is to provide a variable valve lifter mechanism of simple design and construction and having a minimum number or" parts yet highly efiicient and durable in performance.

Further features and advantages of this invention will appear from a detailed description of the drawings in which:

Fig. l is a fragmentary enlarged section of a variable valve lifter mechanism incorporating the features of this invention.

Fig. 2 is a timing diagram of valve operation at slow speed.

Fig. 3 is a timing diagram of valve operation at high speed.

As an example of one embodiment of this invention there is shown a cam shaft having the usual cam lobe 11 which engages the abutment surface 12 of the lifter 13 having the cylindrical surface 14 slidingly fitting in the bore 15 formed in the cylinder block 16 of the engine. mounted the push rod plunger 18 supporting the end 19 of the push rod 20 which is connected to actuate the usual valve gear (not shown).

The push rod plunger in the bore 17 of the lifter 13 forms a variable compression chamber 21. In this chamber there is provided a compression spring 22 having one end supported in a recess 23 in the bottom 24 of the lifter 13 and supported at its other end in a recess 25 in the bottom 26 of the push rod plunger 18 so as to normally urge the lifter 13 toward the cam shaft 10 and the push rod plunger 18 toward the push rod 20.

An oil pressure supply groove 27 is formed in the bore 15 in the cylinder block which is connected through a suitable passageway 28 to the usual oil pump (not shown) for the engine. A passageway or port 29 is formed through the wall 30 of the lifter 13 which is in communication with the oil pressure supply groove 27 and the pressure chamber 21 when the abutment surface 12 of the lifter 13 is on the cylindrical portion 31 of the cam shaft 10.

The port 29 is of such size that with slow speed rotation of the camshaft 10 actuation of the lifter 13 by the cam lobe 11 causes sufiicient escape of fluid from the pressure chamber 21 so that push rod plunger 18 moves toward the bottom 24 of the lifter 13 providing The lifter 13 has a bore 17 in which is slidably V 2,931,347 Patented Apr. 5, 1950 ice low and delayed valve lift for eflicient slow speed operation of the engine with a valve timing such as shown in Fig. 2, wherein the area 32 shows the intake valve open period and the area 33 shows the exhaust valve open period.

When the cam shaft is operating at high speed, the port is of such size as to delay the movement of the push rod plunger into thelifter so that high lift and fast timing of the valve results such as shown in Fig. 3 where intake valve opening is shown in the area 34 and exhaust opening shown in the area 35. In either case, after the automatic adjustment of the push rod plunger 18 in the lifter 13 takes place in relation to the speed of the engine, the port 29 is closed off as the lifter 13 is raised above the edge 36 of the groove 27 so as to lock in the adjustment made each time the lifter is actuated.

While the apparatus herein disclosed and described constitutes a preferred form of the invention, it is also to be understood that the apparatus is capable of mechanical alteration without departing from the spirit of the invention and that such mechanical arrangement and commercial adaptation as fall within the scope of the appcndent claims are intended to be included herein.

Having thus fully set forth and described this invention what is claimed and desired to be obtained by United States Letters Patent is:

1. A variable valve lifter for an internal combustion engine comprising, a litter reciprocatable in a bore in the engine block having a camshaft with an actuating lobe and a cylindrical portion engaging said lifter for controlling the operation of said lifter a push rod plunger connected to operate a valve push rod reciprocatable in said valve lifter and forming with said lifter a fluid pressure chamber between said lifter and said push rod plunger, a source of fluid pressure, a port in said valve lifter located between the bottom of said lifter and the bottom of said push rod plunger directly connected to said chamber and to said source of fluid pressure, said port being so located in said lifter as to be closed off from said chamber and said source of fluid pressure when said lifter is riding on the lobe of said camshaft.

2. In a variable valve lifter as set forth in claim 1 wherein said port is closed off from said source of fluid pressure when said lifter is riding on said camshaft lobe and said port is closed otf from said chamber by the relative movement of said push rod plunger in said lifter when said lifter is engaged by said camshaft lobe.

3. A variable valve lifter for an internal combustion engine comprising, a lifter reciprocatable in a bore in the engine block having a camshaft with an actuating lobe and a cylindrical portion engaging said lifter for controlling the operation of said lifter, a push rod plunger connected to operate a valve push rod reciprocatable in said valve lifter and forming with said lifter a fluid pressure chamber between said lifter and said push rod plunger, a source of fluid pressure, a port in said valve lifter located between the bottom of said lifter and the bottom of said push rod plunger directly connected to said chamber and to said source of fluid pressure, said port being so located in said lifter as to be closed off from said chamber by said push rod plunger when said lifter is riding on the lobe of said camshaft.

4. In a variable valve lifter as set forth in claim 3 wherein said chamber is closed off from said source of fluid pressure by the relative movement of said push rod plunger in said lifter when said lifter is engaged by said camshaft lobe.

5. A variable valve lifter for an internal combustion engine comprising, a lifter reciprocatable in a bore in the engine block having a camshaft with an actuating lobe and a cylindrical portion engaging said lifter for controlling the operation of said lifter, a push rod plunger connected to operate a valve push rod reciprocatable in said valve lifter and forming with said lifter a fluid pressure chamber between said lifter and said push rod said chamber and to said Source of fluid pressure, said port being so located and so proportionedin size QfDPflning in said lifterthat the plunger'cuts ofl said port-during low speed operation of said cam shaft while keeping said port open to 'said chamber during high speed opera tion of said camshaft.

6. A variable valve lifter for, an internal combustion engine as set forth in claim 5 wherein the fluid is -n1e-.,

'4 tered out of said pressure. chamber into said source of fluid pressure during the operation of said camshaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,353,993 Fisher j 'Sept. 28, 1920 2,719,515 Archangeli on. 4, 955 2,749,892 Line June 12, 1956 2,760,470 'Bergmann 'Aug. 28, 1956 ,745 Purchas Oct. 16, 1956 2,691,993 Hubbard May 14, 1957 FQREIGN PATENTS 536,674 Great Britain May 22, 1941

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