WO1995023912A1

WO1995023912A1 - Variable action arrowhead shaped cam lobe system

Info

Publication number: WO1995023912A1
Application number: PCT/GR1994/000002
Authority: WO
Inventors: Christos Valasopoulos
Original assignee: Christos Valasopoulos
Priority date: 1994-03-03
Filing date: 1994-03-03
Publication date: 1995-09-08
Also published as: KR960702049A; EP0705382B1; AU6155494A; EP0705382A1; DE69411743T2; DE69411743D1; JPH08511600A; KR0160202B1

Abstract

Variable action arrowhead shaped cam lobe system properly shaped so that it can cooperate completely with rotating shaft having a longitudinal hole for bearing lubrication, through which hole and a transverse opening, a combined hydraulic and mechanical action moves and changes gradually the lifting of the above-mentioned lobe and simultaneously allows the successive change of the lifting of the valves of the respective cylinder.

Description

DESCRIPTION Variable action arrowhead shaped cam lobe system. FIED OF THE INVENTION The inventicn refers to a new system and method that provi¬ des the capability to an arrowhead shaped cam lobe to move gradually between a lower and an upper position, changing therefore gracually and succesively the lifting of the valves of the respective cylinder of an Internal Combustion Engine (I.C.E.), with the purpose of improving the basic operational characteristics and the efficiency of the I.C.E. BACKGROUND OF THE INVENTION Systems that would reduce the disadvandages occuring in the operation of I.C.E., equiped with conventional camshafts, have been apllied in a very limited extend and in certain I.C.E. sofar.

Refering tc the invention with Patent No. DE 42 22 477 A1 which refers ro a variable cam, which operates whether through its fixed cam segment or through the combination of fixed-movable segment, we observe that in this invention: a) The hydraulic means for transmitting moving action to the cam, succeeds in moving the cam to the "out" position and returning it to the "in" position, with result the li- miting of the torque and power improvement of the engine, only in certain positions. b) It has serious tightness problems in the hydraulic pressure chamber, due to the size of the chamber, the complicated system, the necessary high hydraulic pressure for holding the cam on the "out" position, where the cam is forced down from the respective valve lifter. c) The cams due to the increased solid mass, especially in the configuration FIG.9, will develop during their operation serious problems from inertia forces. d) Obvious manufacturing and assemblying difficulties. (FIG. 2,3,9). e) It cannct be applied to engines where the distances between the cams are limited, as for example with the engi¬ nes V6 and V8 used by the; autoindustries in the U.S.A., CANADA, AUSTRALIA etc.

The present invention respectively is succesfull in: a) Smooth and graduall raising and returning of a

SUBSTITUTE SHEET properly shaped cam lobe employing also the important advanta¬ ge,- concerning the valves of the same cylinder, of having the gradual change of the valve lifting of one valve to be prece¬ ded by a proper time space to the other, in such a way as to result in smoother distribution of torque and power of the engine in its r.p.m. range. b) Complete tightness of the small required hydraulic pres¬ sure chamber, in the lower cylindrical portion of the cam lo¬ be, where it is required only the supplied hydraulic pressure from the lubrication system of the engine, resulting in the application of the invention without any problem. c) Safe and smooth raising of the cam lobe and resting on the cylindrical recess of the rotating shaft. Minimisation of load and inetria forces problems. d) The present invention allows also the simple, fast and economical manufacturing of the cam and the other elements and ease of assemblying as it is obvious from the following drawings. e) It is applied in all existing I.C.E. types without any need for design change.

BRIEF DESCRIPTION OF DRAWINGS FIG.1 : Shows views of the rotating shaft. FIG.2 : Shows the above mentioned system with the cam lobe on its initial position. FIG.3 : Shows the above mentioned system with the cam lobe on its final position.

FIG.4 : Shows views of the longitundinal reciprocating shaft.

FIG.5 : Shows a special configuration of the above mentio- ned shaft.

FIG.6 : Shows several views of the arrowhead shaped cam lobe.

FIG.7 : Shows a special design of the cam lobe. FIG.8 : Shows a mounting system of cam lobes on a simple construction allowing the grinding in pairs. DETAILED DESCRIPTION OF THE INVENTION Refering to the Drawings 1,2,3,4,6 we observe that the system consists of the rotating shaft (1), which is equiped with the arrowhead shaped movable cam lobes (2), the longi- tudinaϊ reciprocating shaft (3), the ball (4) and the spring

SUBSTITUTESHEET (5). The cam lobe has a special cylindrical configuration on its lower end, so that it can be assembled in the respe¬ ctive cylindrical opening of the shaft (1) in a secure way. It has also a longitundinal opening through which the shaft (3) passes. In the inside of the opening the inclined ramp

(6) is shaped, and corresponds with the slope of the ramp

(7) on shaft (3). This shaft has an appropriate number of longitudinal grooves, through these grooves the circulation under pressure of the hydraulic fluid, used also for I.C.E. lubrication, is eased, so that the areas on shaft (1) equi- ped with the cam lobes are always under hydraulic pressure, which pressure is also supplied for the lubrication rf the engine. This pressure is adequate in any case to overcome the reaction of spring (5) and the hydraulic fluid passes through the vertical hole (11) of the lobe and floods the chamber (9) between the shaft (1) and the cam lobe (2). In this way the cam lobe (2), forced by the fluid, is raised untill the lobe ramp (6) coincides with the ramp (7) of the shaft (3). In this position the lobe remains raised thanks to the following mechanism:

During the time that the cam lobe is not in contact with the respective valve lifter the lobe (2) and the shaft (3) remain in contact since the ramps (6) and (7) coincide. In this case the ball (4) is completely inside the vertical hole (11) (spring retracted) simply touching the ramp (7). As soon as the lobe comes in contact with the respective valve lifter, a force is applied on it greater that the force applied by the hydraulic fluid in chamber (9), and momentarily it gives in. This retreat results in the upward movement of the call (4), through the spring (5), and the complete fit on the specially shaped, like a seating,upper part of hole (11), making the whole space tight and at the same time capturing the hydraulic fluid inside the chamber (9), so that no further retreat of the lobe is possible during the hole time of its conctact with the valve lifter (FIG.6) .

Movement of the shaft (3) towards the direction (a) (FIG.3) results in pushing back to a certain distance the ramp (7) from ramp (6). Respectively the under pressure hydraulic fluid passing through the vertical hole (11)

SUBSTITUTE SHEET forces the cam lobe upwards untill the ramps (6) and (7) come again in contact. In this way and according to the mechanism we described earlier the lobe is secured in a new position during its contact with the respective valve lifter. This procedure can be repeated untill the cam lobe takes its upper position, depending on the configuration (length, slo¬ pe) of the ramp (7) on shaft (3).

The gradual retraction of the lobe to its initial posi¬ tion is achieved by the gradual movement of the shaft (3) towards the opposite direction. Indeed this movement results initially in pushing the ball (4) by ramp (7) which Denetra- tes inside the hole (11), and further more in pushing the ramp (6), with the final result the whole lobe to move down¬ wards. The hydraulic fluid in chamber (9) can escape through the vertical hole (11), since the ball (4), being already pushed by the ramp (7) does not rest on the upper "seating" end of hole (11) , and does not provide therefore any tight¬ ness in the chamber (9). In any intermediate position the lobe is secured by the mechanism already described (Page 3 lines 21-36) .

Refering to FIG.3 we observe a special configuration of the longitudinal shaft (3), which is forseen so that the change in lifting of a valve through the ramp (7) to fol¬ low, at a proper time lapse, the change in lifting of another valve of the same cylinder through the ramp (7a), so that a smoother distribution of the torque and power of the engine is achieved through the whole range of its r. p.m. range.

Refering to FIG.7 we see a configuration of the cam lobe consisting of two parts assembled together with a tight fit for reasons: ofI^'manufacturing ease.

The above mentioned cam lobe properly shaped, coopera¬ tes as its different positions completely with the cyli¬ ndrical base of the rotating shaft (1). Obviously the above mentioned cam lobe can cooperate with fixed cams too. Concerning the grinding of cams, as it is well known, this is executed with the method of copying tool machines through the respective PROFILE-MASTER CAM. With conventio¬ nal cams the grinding procedure is executed on one cam

SUBSTITUTESHEET /23912

5 each time (FIG. 8,b2) through the PROFILE-MASTER CAM (FIG.

8, b1) . On the other hand with the cam lobe configuration of the present invention the grinding procedure is executed in pairs of cam lobes mounted on a simple construction (FIG. 8, a2, a3) through the special PROFILE-MASTE CAM (FIG.8,a1), which method is obviously faster and more economical, than the conventional method usually applied.

SUBSTITUTE SHEET

Claims

CLAIMS 1. Variable action arrowhead shaped camlobe system chara¬ cterized by tϊie.^fact that it changes gradually, the lifting of the lobe and simultaneously it allows the succesive change of the valve lifting of the valves of^'the respective cylinder of an Internal Combustion Engine and includes: a) One at least movable cam lobe properly chaped to an arrowhead figure (FIG.6) resting on a proper opening and hole of the rotating shaft (FIG.2). b) A rotating shaft with a longitudinal hole for lubri- eating the bearing seats and transverse vertical hole on it (FIG.1 ) . c) A combined hydraulic and mechanical system, which through a properly shaped reciprocating shaft (FIG. ) insi¬ de the longitudinal hole of the rotating shaft acts on the vertical transverse hole (FIG. 3,6) and moves the special¬ ly shaped lobe, acting constantly under the hydraulic pres¬ sure only, provided by the lubrication fluid pressure of the engine.

This system improves the basic operational characteri- sties and the efficiency of the Internal Combustion Engine with the gradual and succesive lifting of its valves.

2. Variable action arrowhead shaped cam lobe system according to claim 1 characterized by the fact that the moving cam lobe is properly shaped in an arrowhead figure so that its lower cylindrical portion, penetrating the transverse opening of the rotating shaft and resting on it, coincides on its side curved surfaces, with the curved surface of the rotating shaft, which constitutes with the lobe the cyclic base (RUN OUT) of an unified cam in the present claim (FIG.2) cooperating smoothly and constantly with it, resulting in the smooth and without obstacles sliding of the lifter (or fulcrum or roller tappet) during the whole time. of its movement.

3. Variable action arrowhead shaped cam lobe system according to claim 1, characterized by the fact that as means for its movement is used a combined hydraulic and mechanical system which consists of: a) a reciprocating shaft inside the longitudinal hole, for bearing lubrication,of the rotating shaft, which has

SUBSTITUTESHEET on its surface longitudinal grooves, for the flow of pres¬ surized fluid and properly shaped sliding surface locations (FIG. ) and b) a spring and ball acting under each respective sliding surface inside the small space, under hydraulic pressure,on the lower cylindrical part of the moving lobe, characterized by complete tightness. (FIG.6, 3).

This system being constantly under pressure - which is supplied only for the engine lubrication - allows the lobe to move during its extention and retraction gradually and also at the same time allows the succesive change of the valve lifting of the respective cylinder, resulting in the distribution of torque and power through the whole r.p.m. operational range of the engine, applied to all the Internal Combustion Engine rypes.

4. Variable action arrowhead shaped camlobe system accor¬ ding to CLAIM -2 characterized by the fact 'that the grinding process is possible to be applied on pairs of lobes mounted axialy on the recess of a simple construction where the who- le operation is done according to the method followed by the copying masc^'hines through the respective PROFILE-MASTER CAM. This method is obviously faster,and more economical from the cam grinding of the conventional camshafts used by the autoindustry and general industry.

SUBSTITUTESHEET