US2980089A - Valve operating means and control - Google Patents

Description

April 18, 1961 A. c. sAiviPlEfko VALVE OPERATING MEANS AND CONTROL 3 Sheets-Sheet '1 Filed Aug. 26 1959 INVENTOR 5W fiddle; diam 9 2 m N a N\ Nu QM 3 Q &

M 3 N *m 3 x mm 3v m um w km 1 mm a R mu \m \r z v Mm llillil 3 L m 3 April 18, 19 1 A. c. SAMPIETRO VALVE OPERATING MEANS AND CONTROL 3 Sheets-Sheet 2 Filed Aug. 26, 1959 0 s m o M m m M C 5 WM w A 5 a M Q flaw NM R Q Q9 Illlllr lllll IIL ||Ll|||l|vll .1 N E II |||||Il|||1l||||J|| BL .|||||||ml!llI 1 m 3 A) mu G QM & I s fi w N u\ April 18, 1961 A. c. SAMPIETRO VALVE OPERATING MEANS AND CONTROL 3 Sheets-Sheet 5 Filed Aug. 26, 1959 Na 3 5 Q R fi &4 ATTORNEY 5 United States Patent VALVE OPERATING MEANS AND CONTROL I Achilles C. Sampietro, Birmingham, Mich., assignor to Thompson Ramo Wooldridge Inc, Cleveland, Ohio, a corporation of Ohio Filed Aug. 26,1959, Ser. No. 836,238

11 Claims. (Cl. 123-90) The present invention'relates to improvements in mechanism for operating valves of an engine and particularly to mechanism for changing valve operation while the engine is running.

The present invention contemplates the provision of a valve operating mechanism in an internal combustion engine having overhead inlet and exhaust valves operated by rocker arms pivotally supported on the engine. In a preferred form the rocker arms extend laterally outwardly and downwardly to operate the intake and exhaust valves and at their inner ends engage a cam on a singlecam shaft. its axial length to vary the valve events such as the valve timing and the valve lift during operation by shifting the cam shaft axially relative to the rocker arms. The cam shaft is preferably shifted in response to changing engine speed but can be changed in response to other engine operating factors to obtain optimum valve operation throughout the engine speed range.

An object of the present invention is to provide an improved valve operating mechanism for an internal combustion engine or thelike which operates to change the valve events. I 1

Another object ofthe invention is to provide an improved valve operatinggear for controllably changing valve events such as valve timing and valve lift for optimum valve operation at low idling speeds, for maximum torque throughout the speed range, for increased power, and for improved fuel economy.

A still further object of the invention is to provide an improved valve operating gear utilizing a single cam for operating rocker arms for intake and exhaust valves and changing the operation of bothgvalves simultaneously as a'function of engine speed or other factors aifecting engine operation. I

Other objects and advantages will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims, and drawingsin which: 2

Figure 1. is a vertical sectional view taken through a cylinder of an internal combustion engine provided with The cam has a changing profile along a valve in head type of engine to which vthe valve operating mechanism of the invention may be adapted. The internal combustion engine illustrated includes a cylinder block 11 and a cylinder head 12. The head 12 is provided with'an intake passage 14 from a suitable manifold and an exhaust passage 16 leading to a suitable manifold, with the manifolds not being shown. The intake of the fuel air mixture into a cylinder 13 is controlled by an intake valve 18 shown to be of the poppet type with a valve stem 19 slidable in a stem guide 17 mounted in the head 14. The valve 18 has a head 21 which coacts with a valve seat 22 to open or close the intake passage 14 as the intake valve 18 is opened and closed. I

The exhaust passage 16 is provided with an exhaust valve 24 having a valve stem 26 slidable in a valve guide 23 in the head. The valve 24 has a valve head 27 which coacts with a valve seat 28 formed in the engine head in order to control the flow of exhaust gases from the cylinder 13 as the poppet type valve 24 is opened and closed. I

The valves 18 and 24 are opened and also closed by rocker arms 29 and 30 respectively for the intake and exhaust valves 18 and 24. The rocker arms are actuated by a single cam shaft 31 carrying a cam 32. The cam 32 has a changing or differing profile axially along its length and the cam shaft sliifts axially and 'islcontrollably positioned relative to the rocker arms 29 and 30 to change the valve events relative to the operation of the engine for optimum performance of the engine.

The rocker arms 29, 30 are pivotally mounted on the 7 engine head -12 on a post 33, 34 respectively, which are a valve operating mechanism in accordance with the principles of the 'present invention;

Figure 2 is a vertical sectional view taken substantially along line IIII of Figure 1 illustrating details of a mechanism for axially shifting the cam shaft;

Figure 3 is a vertical sectional view taken substantially along line III III of Figure 2 to illustrate the designof the cam;

is operating at 'a high spe showing another arrangementof the'cam.

"Asis-hown on the drawings: I I I In Figure 1 there isillustratedin a fragmentary manner Figure 5 is a vertical sectional view similar to Figure 3 in Figures 12' and. 4, .by a coil compression spring tigconcave central bearing surface, shown at 35 for the rocker arm 30. Since rocker arms 29 and 30; are similar in detail only rocker arm 30 need be described. The bearing surface 35 coacts with a lower fragmentary spherical surface of a bearing member 36 mounted on the post 34 and held in adjusted position by a threaded nut 37 and a lock nut 38, threaded to the top end of the post, and adjusted to obtain the proper valve operating clearance for the rocker arm. The outer ends .of the rocker arms 29, '30 have surfaces 39, 4t) which engage the upper ends of the valve stems 19,;2'6-for forcing the valves open with pivotal movement of the rocker arms 29, .30. The rocker arms are pivoted by rollers 41, 42, rotatably mounted on .roller shafts 43, 44fon the rocker arms 29,-30'respectively, the rollers engaging the outer surface of the cam 32. The rollers 41 and 42 are crowned so as' to engagethe tapered cam 32 as illustratedby the roller 41in Figures 2 and 4, so that the rollerswill have substantially ,pointengagement with the cam to travel in a plurality of paths depending upon the relative axial position of the cam.

As illustrated in Figures). and 4, the cam shaft 31 is driven by the engine by 'a gear 48 connected to the cam shaft 31 by splines Sll. The gear 48 and the splines 50 permit the shaft to be shifted axially with respect to the gear and engine head and the gear is rotatably supported with'itshub mountedjon ball bearing units '45 and 46. The ball bearingunits support the-shaft and the shaft is directly supported on a sleeve bearings-7. The gear 48 will be driven, by a meshing gear driven from the engine, and is held against axial shifting by being lOCkBd'lO'lhG ball bearing .45. by--'a radially contracting sna'pring 49 withxthe'iball bearing axially mounted in the member. 1211 and held therein by a plate- 12b which maybeparts ofithenengine head 12. v The camgshaftfil isl urged axially, to-the left as shown bearing against a plate 51 secured to the end of the cam shaft 31, with the other end of the spring hearing against the hub of the gear 48. The axial movement of the cam shaft from the spring 52 is limited by a snap ring 53 which snaps into a groove in the cam shaft and engages a member of a speed responsive shaft control mechanism shown generally at 54.

The cam shaft is shifted axially from the position of Figure 2 which it occupies when the engine is not operating to the position of Figure 4 which'it occupies at full engine speed. In the non-operating or low speed position of Figure 2, the cam follower rollers 41 and 42 engage the cam surface 32 at 55, and at the high or full speed operating position the rollers engage the cam surface at 56, as shown in Figure 4. At speeds between idling speed and full speed the cam followers will engage various axial portions of the cam 32, that is, they will follow various tracks around the cam dependent on the axial position of the cam which is controlled by the speed responsive mechanism 54.

The speed responsive mechanism 54 includes a first plate 57 which is mounted on the hub of the gear 48 to rotate therewith, and includes a second plate 58 which is secured to the splines on the shaft 31 to move axially with the shaft. The plate 57 has an inner segmental conical surface 59 and the plate 58 has an inner segmental conical surface 60, and between the surfaces are located balls.61 and 62. The halls are guided in grooves 63 and 64 formed in the surface 60. The balls of course will be subjected to centrifugal force with rotation of the shaft 31 and as the shaft gains speed the balls will move outwardly between the surfaces 59 and 6f forcing the plate 58 to the right as shown in Figures 2 and 4, compressing the spring 52, and shifting the cam 32 to the right with respect to the cam followers.

The arrangement permits providing cams with changing profiles along their axial lengths and with the profiles changed in accordance with the characteristics of the engine and use to which the engine is adapted for optimum engine operation. As illustrated in Figure 3, the length of valve events (the length of time the valves are open) may be a at one end of the cam and may be a smaller value ml at the other end of the cam. The cam 32' of Figure 3 shows the difference between a: and oil as being equally split between the two sides of the cam. The carn 32" of Figure shows the difference between a and 041 all on one side of the cam, and the difference may be unequally divided in accordance with valve operating requirements.

The cam 32 of Figure 3 illustrates substantially the constant lift 1 for the length of the cam. The cam 32" of Figure 5 illustrates a change in lift along the cam from I to 1 The cam 32 of Figure 1 shows a change in lift and a change in length of events along the earn. 1

When the difference in length of the events between a and ocl is taken all on one side of the cam, as illustrated by the cam 32" of Figure 5, the peak of the cam surface will vary by an angle and obtains the advantages hereinabove setforth'. The mechanism operates automatically during engine operation to obtain the best valve timingfor all engine speeds.

Thisachieves improved operational characteristics at low 4 idling speeds, maximum torque throughout the speed range, increased power, and improved fuel economy. Further, as it is not necessary to compromise the requirements of good torque in the middle range of speed, consistent idle, good power, and good fuel economy in a single cam profile, it is possible to use power cam accelerations with longer events at high speed shortening the events as required at lower speed.

The speed responsive mechanism 54 represents a control which varies the cam position in accordance with factors which affect engine operation. The axial motion of the cam can be controlled by a load responsive speed modulator. Furthermore, the axial position could be controlled by a hand operated mechanism, either directly or through a servo device.

The drawings and specification present a detailed disclosure of preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. A valve operating mechanism for an engine having intake and exhaust poppet valves with valve stems mounted at an angle in an operating plane comprising a rotary cam shaft having a cam thereon differing in profile along its axial length, means rotatably supporting said cam shaft for axial shifting movement, a first pivotally supported rocker arm extending outwardly and downwardly from the cam shaft in said operating plane with the inner end in engagement with the cam for operating the intake valve of the engine, a second pivotally supported rocker arm extending outwardly and downwardly from the cam shaft opposite to said first rocker arm and in said operating plane with the inner end in engagement with thecam for operating the exhaust valve of the engine, shifting means connected to said cam shaft to axially position the cam with respect to said rocker arms, and speed responsive means driven by the engine connected to said shifting means for controlling the axial operating position of the cam with respect to the followers for different valve operating characteristics.

2. A valve operating mechanism for an engine COLD: prising a cam follower for operating a valve of anengine, a valve operating cam in engagement with the follower having a, cam surface differing in profile 'to provide a plurality of different follower paths having different characteristics, means for driving said camsurface at a speed which is a function of thespeed of the engine, and means for axially shifting said cam surface so that the follower will follow one of said different follower paths to operate the valve in accordance with the path engaged by the follower.

3. A valve operating mechanism for an engine comprising a cam follower for operating a valve of an engine, a rotary cam shaft having a cam surface thereon in engagement with the .follower differing in "profile along its axial length for change in operating characteristics, means for rotating said cam shaft at a speed'whi'ch is a function of the speed ofthe engine, and means for shifting said cam shaft axially so that the follower will be valve operating mechanism which meets the objectives located at different axial positions along the cam for change in operating characteristics. v p

4. A valve operating mechanism for anengine comprising a cam follower for operating a valve of an engine, a valve operating cam in engagement with the follower having a cam surface differing in profile to ,providea plurality ofdifferent follower paths having different characteristics, means for driving said cam surface at a speed which is a function of thespeed of the engine, and speed responsive means to bedriven .as a function of engine speed for axially shifting said cam. surface so that the follower will engage oneofsaid different. follower paths to operate the valve in accordance with the relative positions of the cam and follower.

5. A valve operating mechanism for an engine comprising a cam follower for operating a valve of an engine, a rotary cam shaft having a cam surface thereon in engagement with the follower difiering in profile along its length for change in operating characteristics, means for rotating said cam at a function of engine speed, andof an engine, means for driving the cam shaft in rotation at a function of engine speed, means for shifting said cam shaft axially to cause the follower to engage the cam at different axial locations, and condition change responsive means responsive to change in engine operating conditions connected to said shifting means for controlling the relative axial operating position of the cam and follower.

7. A valve operating mechanism for an engine comprising a rotary cam shaft having a cam thereon, said cam differing in profile along its axial length, a first cam follower in engagement with the cam for operatingan intake valve of an engine, a second cam follower in engagement with the cam for operating an exhaust valve of the engine, means for driving the cam shaft in rotation at a function of engine speed, and means for shifting said cam shaft axially relative to said followers to cause the followers to engage the cam at different axial locations for different valve operating characteristics.

8. A valve operating mechanism for an engine comprising a rotary cam shaft having a cam thereon, said cam differing in profile along its axial length, a first rocker arm at one side of the cam shaft with a follower at the inner end in engagement with the cam for operating an intake valve, a second rocker arm at the other side of the cam shaft with a follower at the inner end in engagement with the cam for operating an exhaust valve, means for driving the cam shaft in rotation at a function of the speed of the engine, and means for shiftingsaid cam shaft axially to cause the followers to engage the cam and operate at different axial locations for different valve operating characteristics.

9. A valve operating mechanism for an engine comprising a rotary cam shaft having a cam thereon, said cam differing in profile along its axial length, a first rocker arm at one side of the cam shaft with a follower at the inner end in engagement with the cam for operating an intake valve, a second rocker arm at the other side of the cam shaft with a follower at the inner end in engagement with the cam for operating an exhaust valve, means for driving the cam shaft in rotation at a function of the speed of the engine, means for shifting said cam shaft axially to cause the followers to engage the cams and operate at different axial locations for different valve operating characteristics, and speed responsive means to be driven bythe engine connected to said shifting means for controlling the relative axial operating position of the cam and followers.

10. A valve operating mechanism for an engine comprising a rotary cam shaft having a cam thereon, said cam differing in lift along its axial length, means for driving the cam shaft in rotation at a function of the speed of the engine, a cam follower in engagement with the cam for operating a valve of an engine, and means for shifting said cam shaft axially to cause the follower to engage the cam and operate at different axial locations for difierent valve operating characteristics.

11. A valve operating mechanism for an engine comprising a rotary cam shaft having a cam thereon, said cam differing in the rotational location of maximum lift along its axial length to' change valve timing, a cam follower in engagement with the cam for operating a valve of an engine, means for driving the cam shaft in rotation at a function of the speed of the engine, and means for shifting said cam shaft axially to cause the follower to engage the cam and operate at different axial locations for different valve operating characteristics.

References Cited in the file of this patent UNITED STATES PATENTS 1,175,395 Wixon Mar. 14, 1916 1,556,410 Boyer Oct. 6, 1925 2,397,511 Schreck Apr. 2, 1946 FOREIGN PATENTS 959,254 France Sept. 26, 1949 674,180 Great Britain June 18, 1952

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