US3306270A

US3306270A - Valve operation system

Info

Publication number: US3306270A
Application number: US381485A
Authority: US
Inventors: Eugene L Mccarl
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-07-09
Filing date: 1964-07-09
Publication date: 1967-02-28
Anticipated expiration: 1984-02-28

Description

Feb. 28, 1967 E. L. MCCARL 3,306,270

VALVE OPERATION SYSTEM Filed July 9, 1964 n ig INVENTOR EUGENE L. M CARL ATTORNE Y8 United States Patent Ofifice 3,306,270 VALVE OPERATION SYSTEM Eugene L. McCarl, 834 Wyolen St., Jacksonville, Fla. 32205 Filed July 9, 1964, Ser. No. 381,485 9 Claims. (Cl. 123-90) This invention relates to a novel and improved valve operating system for use in internal combustion engines.

This invention is primarily concerned with internal combustion engines of the type wherein a poppet valve is used to control fluid flow into or out of each cylinder of the engine. In most engines one valve is used to control admission of an explosive mixture into the cylinder, and a separate valve is used to permit the flow of combusted gases from the cylinder of the engine. In such engines, valve operating systems must be provided to efl'ect and control the opening and closing of each valve associated with each cylinder. conventionally, such systems comprise a cam shaft driven by the engine and carrying a plurality of cams one for each valve. The valve is mounted for movement toward and away from a valve seat on the engine block and may carry a tappet which is engageable with the respectively associated cam for movement of the valve away from its seat. Also, conventionally, a preloaded spring is provided to act between the valve and engine block and urge the valve toward its seat or in a closing direction. Rather than carrying a tappet, each valve may be engageable by one end of a rocker arm, the other end of which is engageable with one end of a lift rod carrying a tappet at its other end which is engageable with the cam associated with the valve. In this latter construction the cam engages the tappet to lift the lift rod and pivot the rocker arm to move the valve away from its seat. Again, conventionally, a preloaded spring may be utilized to return the valve to its seat.

In another known valve operating system, hydraulic valve lifters are utilized. A hydraulic lifter may conventionally comprise a cylinder attached to the lift rod of a rocker arm mechanism with a piston in the cylinder fixed for movement with a tappet engageable with a valve cam. The cylinder is filled with oil, whereby, as the tappet and thus the piston are raised by the cam, force is transmitted through the oil to the cylinder end wall to move the cylinder and thus the lift rod in a direction to open the valve. A preloaded spring is conventionally used to close the valve.

In all valve operating systems of the type described wherein a preloaded spring it utilized to close the valve, it will be apparent that it is necessary to compress the preloaded spring as the valve is lifted in order to store sufiicient energy in the spring to provide closing of the valve. Such valve springs are preloaded a substantial amount in order to provide a relatively high seating pressure on the valve in order to avoid leakage or burning of the valve seat. The high force represented by the valve springs provide a source of substantial friction between the tappets and cams during opening as well as closing of the valve. Additionally the use of resilient means to close or assist in closing a valve of a high speed engine inherently results in problems in valve timing during high speed running.

It is the primary object of the present invention to provide a novel and improved valve operating system for an internal combustion engine which will provide both positive opening and positive closing of a valve, which will provide a predetermined positive seating pressure, which will eliminate the use of valve springs, and which is a relatively simple and economical construction, yet which is sutficiently rugged to provide a long and trouble free service life.

such as the intake manifold. In the 3,306,270 Patented Feb. 28, 1967 The objects of the invention are achieved in one aspect thereof wherein a valve of an internal combustion engine has its stern mechanically connected for movement with a piston contained within a hydraulic cylinder. The other end of the piston carries a calm follower or tappet engageable with a cam for positive mechanical opening of the valve. The hydraulic cylinder is provided with a chamber containing a substantially incompressible pressurized liquid, preferably the lubricating oil of the engine. The piston is exposed to the liquid in this chamber so that the pressure of this liquid acts on the piston to move the same in a direction corresponding to closing of the valve. This chamber in the hydraulic cylinder is connected in liquid flow communication with a chamber in a second cylinder housing a second piston one end of which is in contact with the liquid in the second cylinder and the other end of which carries a follower or tappet engageable with a second cam. Both cams are preferably mounted on the same cam shaft which is driven -by the engine and have cam surfaces which are generally the reverse of each other. The second cam is engageable with the tappet on the second piston to move the piston in a direction to cause liquid to flow from the second cylinder to the first cylinder and etfect closing of the valve. At least one relief v-alve is provided in the conduit from the first cylinder to the second cylinder. The second cylinder has a displacement substantially equal to and at least slightly greater than the displacement of the first cylinder and the relief valve has a selectively adjustable set pressure whereby the seating pressure of the engine valve may be set at a predetermined value. Thus in this aspect, as well as other aspects, of the invention the engine valve is unseated by a direct, positive, mechanical drive and is seated by a direct, positive, liquid or hydraulic drive.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its oraginzation and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

FIGURE 1 is a generally diagrammatic representation of a valve operating system incorporating the present invention;

FIGURE 2 is a generally diagrammatic representation of a modified form of the invention;

FIGURE 3 is a generally diagrammatic illustration of a further alternate embodiment of the invention; and

FIGURE 4 is a cross-sectional view of a portion of the embodiment of FIGURE 3.

With reference to the drawing and particularly FIG. 1 an internal combustion engine is generally indicated at 10 and comprises a block 12 having a chamber 14 opening into a cylinder 16 housing a piston (not shown). One wall of the chamber 14 is provided with a conical seat 18 for a poppet valve 20. The valve 20 is movable generally vertically upwardly from its seat to provide communication between the chamber 14 and a chamber 24 beneath the valve. The chamber 24, in the case of an intake valve, leads to a source of combustible mixture, case of an exhaust valve the chamber 24 might lead to the exhaust manifold of the engine.

In accordance with the invention, inserted in the bottom wall of the chamber 24 is a cylinder 26. The cylinder 26 may have one end threaded so that it is threadably engaged within the bottom wall of the chamber 24 thus providing a fluid seal with respect to the mixture within the chamber 24. The cylinder 26 extends coaxially of the valve seat and in part defines an expansible chamber 28. A moveable wall of the chamber 28 is defined by one end of a piston 30 which projects into the lower end of the cylinder 26 opposite the valve seat 18. The lower end of the valve stem 22 is rigidly connected to the inner end of the piston 30 and extends coaxially thereof. The lower or other end of the piston 30 carries a roller tappet 32 which is engageable with a cam 34 mounted on a cam shaft 36. The cam 34 and cam shaft 36 may he conventional, with the cam shaft being driven by the engine. With the valve in its seated position there is clearance provided between the roller tappet and cam to allow for expansion of the valve stem induced by the high temperatures encountered by the valve during engine operation. As the cam shaft is rotated the follower 32 will become engaged with the flank of the cam whereby the piston 30 will be raised to raise the valve off its seat and provide communication between the

chambers

14 and 24 in the engine block. A suitable valve stem guide may be provided between the valve stem 22 and fixed end wall of the cylinder 26, said guide also providing a fluid seal between the chamber 24 in the engine block and the chamber 28 of the piston 30. Additionally, suitable means may be provided for adjusting the spacing between the roller tappet 32 and the valve head in order to permit selective adjustment of the clearance between the tappet and the cam 34.

A liquid flow passage 38 is provided, preferably in the engine block, with one end of the passage 38 communicating with the chamber 28 in the cylinder 26. The other end of the passage 38 communicates with an expansible chamber 42 formed in part by a cylinder 40. A moveable wall for the chamber 42 is provided by one end of a piston 44 which projects into one end of the cylinder 40 opposite the fixed end wall 46 thereof. The piston 44 carries at its other end a roller tappet 48 which is engaged with a cam 50 which may be mounted for rotation with the cam shaft 36. For a reason which will be hereinafter apparent, the profiles of the

cam

34 and 50 are the reverse of each other. Also, the piston 44 has a greater volumetric displacement than the piston 30. This may be achieved in several ways; however, in the specific embodiment shown in FIG. 1, this is achieved by providing the piston 44 with a diameter greater than that of the piston 30 and maintaining the strokes of the pistons the same. Alternately, the major throw of the cam 50 could be made greater than the major throw of the cam 34 and the diameters of the

pistons

30 and 44 be maintained equal.

Connected to the conduit 38 is a oneway, spring loaded, ball check valve 52. The valve 52 is connected by a passage 54 to the engine oil supply whereby oil will be fed into the conduit 38 at engine oil pressure, for example 60 psi. The check vave 52 prevents oil from flowing from the passage 38 in a reverse direction through the valve into the passage 54, thus assuring that the passage 58 will be filled with oil and at the same time isolating the passage 54 and engine .oil supply from the pressure of any liquid within the conduit 38 which is higher than the pressure of the engine oil supply. Also connected to the conduit 38 is a pressure relief valve 56 having an outlet passage 58 which is connected to the engine oil supply by a conduit (not shown). The relief valve 56 has an adjustable set pressure. This feature is provided by a threaded member 60 which bears on one end of the valve spring 62. The other end of the spring bears on a ball seated in the valve body to prevent the flow of liquid from the passage 38 to the passage 58 except when the pressure in the passage 38 exceeds the pressure set by the predetermined compressive preloading of the spring 62 by the adjusting member 60.

A second pressure relief valve 64 is connected to the passage 38 and comprises a valve body mounting a threaded member or screw 56 on one end of the body with the inner end of the screw bearing on end of the spring 68. The other end of the spring bears on a ball 70 seated in a valve seat on the body to prevent flow from the passage 38 to an outlet passage 72 in the valve body except when the pressure in the passage 38 is greater than the set pressure of the valve as determined by the selective preloading of the valve spring 68 by the adjusting member 66. The outlet passage 72 is connected to the engine oil supply by a conduit (not shown).

In the operation of the valve operating system of FIG. 1, as the cam shaft 36 is rotated from the position shown in FIG. 1, the valve 20 will be lifted from its seat by the positive mechanical drive between the cam 34 and the valve. As the valve is lifted, the piston 30 will be simultaneously moved inwardly of the cylinder 26 causing oil within the chamber 28 into the chamber 42 to displace the piston 44 outwardly of the cylinder 40. As previously mentioned the profile of the cam 50 is the reverse of the cam 34. More particularly, the cams are contoured so that as the cam shaft is rotated to drive the piston 30 into the cylinder the cam 50 will permit movment of the piston 44 in a direction out of the cylinder 40 at least at a rate that will assure that the rate of increase in volume of the cylinder 40 will be equal to if not greater than the rate of decrease in volume of the cylinder 26. As the cam 34 is rotated the nose of the cam will pass through alignment with the longitudinal axis of the valve stem 32 and piston 30, at which point the minor throw of the cam 50 will be aligned with the longitudinal axis of the piston 44. Continued rotation of the cam shaft in the same direction will result in the piston 44 being advanced inwardly of the cylinder 40 by the cam 50 while at the same time the cam 34 will permit movement of the piston 30 outwardly of the cylinder 26.

As previously noted the displacement of the piston 44 is substantially equal to and at least slightly greater than that of the piston 30. Assuming that the piston 44 has a greater diameter than the piston 30 and the piston 44 is advanced into the cylinder 40 at the same rate as the retraction of the piston 30, the tappet 32 will be maintained in firm contact with the cam 34 until such time as the valve is seated. Seating of the valve will occur prior to alignment of the minor throw of the cam 34 with the axis of the piston 30 because of the clearance between the valve tappet 32 and the cam 34. The cam 50 provides for continued advancement of the piston 44 after the valve has been seated over an angular movement of the cam 50 equivalent to the clearance between the tappet 32 and cam 34. This additional movement of the piston 44 after the valve has been seated will raise the pressure of the fluid in the conduit 38 and thus the chamber 28 to provide a relatively high seating pressure on the valve. The seating pressure on the valve will be determined by the selective setting of the

relief valves

56 and 64. In this connection, it is preferred that the valve 56 be located where it is not readily accessible from externally of the engine, while the valve 64 should be located at a point where it is readily accessible from externally of the engine. The valve 56 may, if desired, be connected to a plurality of conduits corresponding to the conduit 38 so as to centrally control the maximum pressure in these conduits without requiring a separate relief valve for each engine valve.

The setting on the valve 56 will provide the maximum pressure within the conduit 38 and being relatively inaccessible will prevent intentional or unintentional setting of the maximum pressure in the system above that which is the maximum safe value. The relief valve 64 on the other hand is used to vary the normal maximum operating pressure where it will be below or at least no greater than the pressure set by the valve 56. The valve 64 thus provides a ready means for adjustment of, and determines, the seating pressure on the engine valve 20. Like the valve 56, the valve 64 may be connected to a plurality of conduits similar to the passage 38 thus providing a central control of seating pressure for a plurality, or all, of the engine valves 20. The relatively high seating pressure, for example p.s.i., will be maintained in the passage 38, and thus the chamber 28, until such time as the flank of the cam 34 becomes engaged with the roller tappet 32. At this time the piston 44 will be free to move outwardly of the cylinder 40. The greater displacement of the piston 44 will assure that advancement of the piston 30 will be against a pressure no greater than engine oil supply pres sure. However, the greater displacement of the piston 44 will require that make up oil be provided to the system upon retraction of the piston 44. This make up oil will be provided through the one way check valve 52 from the engine oil supply. As will be apparent from the foregoing, as the cam 50 moves the piston 44 into the cylinder 40 there will be a steady rise in the pressure of the liquid in the chamber 28 of the cylinder 26. This pressure may remain below the set pressure of the relief valve 64 until the engine valve 20 is seated, whereupon the continued advancement of the piston 44 into the cylinder 40 will cause a rapid rise of the pressure in the passage 38 to the set pressure of the relief valve 64.. In this connection it is to be noted that if the pressure in the passage 38 does not rise sufiiciently due to'the continued advancement of the piston 44 into cylinder 40, i.e., the pressure therein is below the engine oil pressure, pressurized oil from the engine oil supply will pass through the one way check valve 52 into passage 38 to seat engine valve 20, thus at least maintaining the sea-ting pressure on engine valve 20 at the engine oil supply pressure, for example, 60 p.s.i. as hereinabove described.

Thus, it will be seen that the valve 20 is opened against a hydraulic pressure which provides a force between the cam 34 and roller tappet 32 which is substantially less than that which would be present with the usual preloaded valve spring arrangement. Also, the valve is closed positively by a direct acting hydraulic system incorporating no resilient elements, such as spring chambers or the like. The seating pressure of the engine valves may be readily adjusted, with the relief valve 56 being provided to assure that the safe limit of the system is not exceeded. The automatic supply of make up oil on movement of the pistion 44 outwardly of the cylinder 40 assures that the system will be kept free of air. In this connection, it is preferable to locate the relief valves at a high point in the system to assure that when these valves bleed oil from the system, any entrapped air will be carried with the bleed oil. When the engine is stopped the pressure within the conduit 38 and

chambers

28 and 42 will be trapped therein thus maintaining the pressure in the system and assuring that those valves which were seated on stopping of the engine will remain so until the engine is again started.

Thus it will be seen that there has been provided a valve operating system for an internal combustion engine 'wherein the valve is opened by a mechanical driving connection between a first cam and the valve, and wherein a positive hydraulic driving connection between a second cam and the valve serves to close the valve and provide a predetermined seating pressure on the valve after it is seated. -Valve closing is accomplished without the use of any spring or other resilient means in the system while at the same time fast valve closing is assured. The time of valve closing is controlled by the same cam which effects valve opening. The hydraulic portion of the system will be maintained filled with oil regardless of changes in the dimensions of the cylinder 26 or valve 22 when these elements are located adjacent a high temperature zone of the engine. The use of engine oil in the valve system as the hydraulic fluid eliminates the need for a separate oil supply for the valve operating system. It will further be noted that the outlet of the reilef valves as well as any leakage from the hydraulic elements will flow back to the engine oil supply thus assuming no loss of engine oil.

In the embodiment of FIG. 2 the invention is shown in the environment of an overhead valve engine. In this embodiment the valve 120 is moved outwardly away from its seat in the engine block 112 to provide communication between a chamber 124 on one side of the valve and acombustion chamber on the other side of the valve leading to the respectively associated engine cylinder. A fixed cylinder 126 housing a piston is mounted above the valve 120. The outer end of the piston 130 is rigidly connected to the valve stem 122. The cylinder 126 is provided with an expansible chamber 126 one wall of which is defined by the inner end of the piston 130. The chamber 128 is connected by a passage 138 to a hydraulic cylinder and cam arrangement (not shown) similar to that shown in FIG. 1 to provide for movement of the piston 130 outwardly of the cylinder 126 with attendant movement of the valve to- Ward its seat. In the embodiment of FIG. 2 a cam shaft 136 and cam 134 are located above the valve 120 rather than below it as in the embodiment of FIG. 1. Also in the embodiment of FIG. 2 the cam 134 is engageable directly with the bottom of piston 130 which serves as a tappet, although the cam and tappet configuration of FIG. 1 could be used in the embodiment of FIG. 2 and vice versa. The operation of the system of FIG. 2 is identical with FIG. 1 and therefore will not be further described.

In the embodiment of FIG. 3, the valve shown in association with an overhead valve engine as in the embodiment of FIG. 2; however, in the embodiment of FIG. 3, the upper end of the valve stem 222 is connected by a link 223 to a rocker arm 225. The link 223 is connected at its opposite ends to the rocker arm and valve stem 222 by ball and socket joints, such as shown in FIG. 4, whereby a positive driving connection is provided between the rocker arm and stem 222 in both directions of angular movement of the rocker arm. The ball and socket joint of FIG. 4 comprises a socket member 229 having a cavity provided with a hemispherical bottom wall 231 and a cylindrical side wall 233. A ball 235 is seated on the hemispherical bottom wall of the socket member and a 220 is again stem 237 fixed relative to the ball extends outwardly of the open end of the cavity of the socket member. A re taining member 239 in the form of annular washer is disposed coaxially over the stem 237 and has its outer side wall threadably engaged with the cylindrical side wall of the cavity in the socket member. The washer 239 is provided with a parti-spherical surface extending from its central aperture receiving the stem 237 with the partispherical surface being slidably engaged with the end of the ball 235 opposite the end wall 231 of the cavity in the socket member. Thus the ball is retained within the socket member and a positive driving connection is provided between the ball and socket member in both directions of movement of the stem 237 generally parallel to its longi tudinal axis. The other end of the rocker arm is connected by a ball and socket joint to a lift rod 227, the other end of which is connected by a ball and socket joint to a piston 230 one end of which projects into a cylinder 226 "FIG. 4 in the socket members being provided on the upper end of the lift rod and with a stem 237' corresponding to the stem 237 being carried by the rocker arm. It is preferred that the stem 237' be adjustably mounted, such as by threading to the rocker arm, to permit adjustment of the effective length of the lift rod 227 to thus provide adjustment of the clearance between the cam 234 and tappet associated therewith.

The cylinder 226 is provided with an expansible chamber 228 corresponding with chamber 28 of the embodiment of FIG. 1. The chamber 228 is connected by a passage 238 to a second cylinder similar to a cylinder 40 of FIG. 1. The operation of the embodiment of FIG. 3 is the same as that of the embodiment of FIG. 1 with the exception that the motion of the piston 230 is transmitted to the valve 220 by means of the lift rod 227 and rocker arm 225 rather than by a direct rigid connection between the piston and valve. On the other hand it will be observed that in the embodiment of FIG. 3 a positive mechanical connection is provided between the piston 230 and valve 220 providing a positive drive of the valve 220 in both directions of movement thereof. It is contemplated that the ball and socket joints described in connection with the embodiment of FIG. 3 will have substantially no play, thus essentially eliminating any relative or lost motion between the valve 220 and piston 230. As will be apparent, the embodiment of FIG. 3 may be used in overhead valve engines wherein the cam shaft is located below the engine valves as differing from the embodiment of FIG. 2 wherein an overhead cam shaft is used.

While only certain preferred embodiments of this invention have been shown and described by way of illustration, many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended in the appended claims to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fluid flow between said cylinder and a passage externally thereof, and a seat for said valve; cam means driven by the engine, means for providing a positive mechanical driving connection between said cam means and valve for opening the valve and including an expansible chamber having a moveable wall connected for movement with the valve and facing in the direction of movement of the wall corresponding to opening of the valve, means providing a second expansible chamber having a moveable wall, means providing a liquid passage between the chambers, a substantially incompressible liquid filling said chambers and passage, said cam means being operatively associated with the moveable walls of said chamber alternately to effect contraction of the first chamber and simultaneous expansion of the second chamber and contraction of the second chamber and simultaneous expansion of the first chamber in response to driving of the cam means, the rate of change of volume of said second chamber during contraction thereof being greater than the rate of change of volume of the first chamber during expansion thereof, and a pressure relief valve connected to said passage to limit the liquid pressure in said passage during contraction of said second chamber.

2. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fluid flow between said cylinder and a passage externally thereof, and a seat for said valve; cam means driven by the engine, means for providing a positive mechanical driving connection between said cam means and valve for opening the valve and including an expansible chamber having a moveable wall connected for movement with the valve and by said cam means and facing in the direction of movement of the wall corresponding to opening of the valve away from its seat, means providing a second expansible chamber having a moveable wall, means providing liquid passage between the chambers, a substantially incompressible liquid filling said chambers and passage, said cam means being operatively associated with the moveable walls of said chamber alternately to effect contraction of the first chamber and expansion of the second chamber to open the valve and contraction of the second chamber and expansion of the first chamber to seat the valve, the volume of liquid displaced by said second chamber during contraction thereof being greater than the volume of liquid displaced by the first chamber during expansion thereof, a pressure relief valve connected to said passage to limit the fluid pressure in said passage during contraction of said second chamber, means for maintaining a predetermined seating pressure of s id valve, and a second pressure relief valve connected to said passage to limit the maximum pressure therein.

3. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fluid fiow between said cylinder and a passage externally thereof, a seat for said valve, and a source of pressurized oil; cam means driven by the engine, means providing a positive mechanical driving connection between said carn means and the valve for opening the valve in response to driving of the cam means and including an expansible chamber having a moveable wall connected for movement with the valve and by the cam means and facing in the direction of the movement of the wall corresponding to opening of the valve, means providing a second expansible chamber having a moveable wall, means providing a liquid passage between the expansible chambers, means connecting said liquid passage to the source of pressurized oil including a one way check valve for preventing oil flow from said passage to said source, said cam means being operatively associated with said moveable walls to effect simultaneous contraction of the first chamber and expansion of the second chamber for opening the valve and alternately to effect simultaneous contraction of the second chamber and expansion of the first chamber for closing the valve with the contraction of said second chamber continuing a predetermined interval after seating of the valve, and a relief valve connected to said liquid passage and limiting the pressure of the oil therein.

4. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fluid flow between said cylinder and a passage externally thereof, and a seat for said valve; reciprocable piston, means providing a positive mechanical driving connection between said piston and valve in both directions of movement of the piston, a cylinder, one end of said piston extending into said cylinder and facing the direction of movement of the piston corresponding to valve opening, said cylinder having an end Wall facing oppositely to and spaced from said one end of the piston, a second cylinder, a second reciprocable piston having one end thereof received within said second cylinder, said second cylinder having an end wall facing oppositely to and spaced from said one end of said second piston, means providing a liquid passage connecting the spaces within said cylinders between said one end of said pistons and said end walls of the cylinders, a substantially incompressible liquid filling said passage and said spaces, cam means driven by the engine, means on each piston operatively associated with said cam means to effect advancement of the first piston toward said end wall of the cylinder and movement of the second piston away from said end wall of the cylinder and alternately to effect movement of said pistons in the opposite directions, the displacement volume of the second piston being greater than the displacement volume of the first piston, and a pressure relief valve connected to said passage to limit the liquid pressure therein to a predetermined value during advancement of said second piston.

5. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fiuid flow between said cylinder and a passage externally thereof, and a seat for said valve; a reciprocable piston, means providing a positive mechanical driving connection between said piston and valve in both directions of movement of the piston, a cylinder, one end of said piston extending into said cylinder and facing in the direction of movement of the piston corresponding to valve opening, said cylinder having an end wall facing oppositely to and spaced from said one end of the piston, a second cylinder, a second reciprocable piston having one end thereof received within said second cylinder, said second cylinder having an end wall facing oppositely to and spaced from said one end of said second piston, means providing a liquid passage connecting the spaces within said cylinders between said one end of said pistons and said end walls of the cylinders, a substantially incompressible liquid filling said passage and said spaces, rotatable cam means driven by the engine, a tappet associated with each piston and said cam means and coupled to the pistons for movement therewith in both directions of movement of the piston, the tappets being engageable by said cam means to effect advancement of the first piston of said end wall of its cylinder and movement of the second piston away from said end wall of its cylinder and alternately to effect movement of said pistons in the opposite directions, the displacement volume of the second piston being greater than that of the first piston, the tappet associated with said first piston being engaged with said cam means during retraction of said first piston to control the movement of the valve toward its seat, and a pressure relief valve connected to said liquid passage.

6. In a valve operating system for an internal combustion engine provided with a cylinder, at reciprocable valve for controlling fluid flow between said cylinder and a passage externally thereof, a seat for said valve, rotatable cam means driven by the engine, and means providing a source of lubricating oil; a pair of cylinders having rigid side and end walls, a pair of reciprocable pistons received at one end within said cylinders with said one end of the pistons being spaced from the end walls of the cylinders, means providing a liquid passage connecting the spaces within said cylinders between said end walls and one end of the pistons, means connecting said liquid passage to said source of oil including a one Way check valve preventing flow of oil from said passage to said source, a pair of pressure relief valve connected to said passage, means for varying the set pressure of said relief valves, each relief valve having an outlet connected to said source of oil, means providing a positive mechanical coupling between one of said pistons and said valve for simultaneous movement of said valve and piston in both directions of movement of the piston, and means on each of said pistons cooperatively engageable with said cam means for timed reciprocation of said pistons in opposite directions in response to rotation of said cam means, the displacement volume of said one piston being less than the displacement volume of the other piston.

7. In a valve operating system as described in claim 6, a rocker arm, providing a positive driving connection between one end of the rocker arm and said valve in both directions of movement of the valve relative to its seat, and means providing a positive mechanical driving connection between the other end of said rocker arm and said one of said pistons in both directions of movements of the piston.

8. In a valve operating system for an internal combustion engine provided with a cylinder, a reciprocable valve for controlling fluid flow between said cylinder and a passage externally thereof, a seat for said valve, and means for providing a source of pressurized oil; a pair of cylinders each having rigid side and end walls, a pair of reciprocable pistons received at one end within said cylinders with said one end of the pistons being spaced from the end walls of the cylinders, means providing a liquid passage connecting the spaces Within said cylinders between said end walls and one end of the pistons, means connecting said liquid passage to said source of oil including a one way check valve preventing flow of oil from said passage to said source, a pair of pressure relief valves connected to said passage, means for varying the set pressure of said relief valves, means providing a positive mechanical coupling between one of said pistons and said valve for simultaneous movement of said valve and piston in both directions of movement of the pistons and for movement of said valve in an opening direction in response to advancement of said one piston into its cylinder, a cam shaft driven by the engine, and a pair of cams mounted for rotation with said shaft, one of said cams being cooperatively associated with said one piston and having a cam surface contoured to drive said one piston into its cylinder and control the movement of said one piston in the other direction, the other cam being contoured generally the reverse of said one cam and being cooperably associated with the other piston to drive the same into its cylinder and permit movement of the piston in the opposite direction in timed relation to movement of the said one piston, the displacement volume of said one piston being less than the displacement volume of the other piston.

9. In a valve operating system for an internal combustion engine provided with a cylinder, a valve for controlling fluid flow between said cylinder and a passage externally thereof, a seat for said valve, and a source of pressurized oil; cam means driven by the engine, means providing a positive mechanical driving connection between said cam means and the valve for opening the valve in response to driving of the cam means and including an expansible chamber having a moveable wall connected for movement with the valve and by the cam means and facing in the direction of the movement of the Wall corresponding to opening of the valve, means providing a second expansible chamber having a moveable wall, means providing a liquid passage between the expansible chambers, means connecting said liquid passage to the source of pressurized oil including a one way check valve for preventing oil fiow from said liquid passage to said source, said cam means being operatively associated with said moveable walls to effect simultaneous contraction of the first chamber and expansion of the second chamber for opening the valve and alternately to effect simultaneous contraction of the second chamber and expansion of the first chamber for closing the valve, the contraction of said second chamber continuing a predetermined interval to at least seat said valve on its said seat thereafter the oil flows from said source through said check valve into said liquid passage when the oil pressure therein is less than the pressure of the oil in said source whereby said valve remains seated on its seat at least at the pressure of oil in said source, and a relief valve connected to said liquid passage and limiting the pressure of the oil therein.

References Cited by the Examiner UNITED STATES PATENTS 1,586,188 5/1926 Fisher 123-90 1,696,984 1/ 1929 Trbojevich 123-90 1,902,996 3/1933 Gerard 123-90 2,342,003 2/ 1944 Meyer 123-92 3,139,077 6/1964 Beucher 123-90 FOREIGN PATENTS 573,596 3/1924 France. 272,414 6/1927 Great Britain.

MARK NEWMAN, Primary Examiner. AL LAWRENCE SMITH, Examiner.

Claims

1. IN A VALVE OPERATING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE PROVIDED WITH A CYLINDER, A VALVE FOR CONTROLLING FLUID FLOW BETWEEN SAID CYLINDER AND A PASSAGE EXTERNALLY THEREOF, AND A SEAT FOR SAID VALVE; CAM MEANS DRIVEN BY THE ENGINE, MEANS FOR PROVIDING A POSITIVE MECHANICAL DRIVING CONNECTION BETWEEN SAID CAM MEANS AND VALVE FOR OPENING THE VALVE AND INCLUDING AN EXPANSIBLE CHAMBER HAVING A MOVEABLE WALL CONNECTED FOR MOVEMENT WITH THE VALVE AND FACING IN THE DIRECTION OF MOVEMENT OF THE WALL CORRESPONDING TO OPENING OF THE VALVE, MEANS PROVIDING A SECOND EXPANSIBLE CHAMBER HAVING A MOVEABLE WALL, MEANS PROVIDING A LIQUID PASSAGE BETWEEN THE CHAMBERS, A SUBSTANTIALLY INCOMPRESSIBLE LIQUID FILLING SAID CHAMBERS AND PASSAGE, SAID CAM MEANS BEING OPERATIVELY ASSOCIATED WITH THE MOVEABLE WALLS OF SAID CHAMBER ALTERNATELY TO EFFECT CONTRACTION OF THE FIRST CHAMBER AND SIMULTANEOUS EXPANSION OF THE SECOND CHAMBER AND CONTRACTION OF THE SECOND CHAMBER AND SIMULTANEOUS EXPANSION OF THE FIRST CHAMBER IN RESPONSE TO