US2954017A

US2954017A - Valve control arrangement for internal combustion engines

Info

Publication number: US2954017A
Application number: US802056A
Authority: US
Inventors: Forstner Egon
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 1958-03-29
Filing date: 1959-03-26
Publication date: 1960-09-27
Anticipated expiration: 1977-09-27

Description

Sept. 27, 1960.

v VALVE CONTROL ARRANGEMENT FOR INTERNAL Filed March 26, 1959 E. FORSTNER COMBUSTION ENGINES 2 Sheets-Sheet l nvmsw r04 EGON FORSTNER ATTORNE S Sept. 2 7, 1960 Filed Marbh 26, 1959 E. FQRSTNER COMBUSTION ENGINES 2 Sheets-Sheet 2 INVENTO/P EGON FORSTNER ATTORNEYS VALVE CONTROL ARRANGEMENT FOR INTERNAL United States Patent VALVE CONTROL ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES Egon Forstner, Stuttgart-Degerloch, Wurttemberg, Germany, assignor to Dr. Ing'. h.c.F. Porsche K.G., Stuttgart-Zulfenhausen, Germany Filed Mar. 26, 1959, Ser. No. 802,056 Claims priority, application Germany Mar. 29, 1958 16 Claims. (Cl. 123-90) The present invention relates to a valve control arrangement for internal combustion engines, especially for relatively high-speed driving engines in which the opening and closing of each valve takes place by. means of an oscillating rocker arm. Valve control arrangements driven by cams are known in the prior art in which the stepped control surfaces of a cam-type rocker arm cooperating with the end of the valve shaft etfectuates the opening of the valve. The closing of the valve takes place in these prior art devices by means of pressure springs operatively connected with the valve shaft. In control arrangements of this type, the power output of the engine made possible by the increase in the rotational speed thereof is limited by reason of the requirements of the valve closure springs necessary therefor. This is so because not only the masses of the springs have to be additionally accelerated but also, with an increase in the rotational speed of the engine, corre- 'spondingly stronger springs have to be provided. However, the increase in strength of the springs cannot be increased at will since the spring forces then assume nonpermissive, undue values which lead to local pressures and entail excessive wear of the rocker arm.

In order to avoid these disadvantages and shortcomings of these prior art constructions, valve control arrangements have already been proposed in which the valve was positively controlled by the use of one separate opening and closure cam each. However, these types of construction are limited to overhead cam shafts, the drive of which require considerable costs in the construction thereof. Since additionally for each valve two cams are required, this type of control becomes relatively expensive and is, therefore, limited in the application thereof to constructionsin which the economic aspects are only of subordinate importance.

According to the present invention, these disadvantages and shortcomings of the prior art are eliminated in that the rocker arm efiectuates over anintermediate lever provided with several control surfaces .the opening and closing movement of the valve. From such construction results the advantage that a closure-spring may be dispensed within the control arrangement according to the present invention and that with a single control member the opening as Well as the closing movement of the valve may be realized. Furthermore, by the use of such an arrangement, it is possible to achieve that the control drive may be taken off, not from an overhead control shaft, but from a normally arranged control shaft disposed below the rocker arm arrangement whereby significant savings in the cost thereof are obtainable. The control elements consisting of the rocker arm and of the intermediate lever I are movably supported, independently of one another, at

a guide member adjustably arranged at the engine housing so that a compact, space-saving construction results therefrom which may be accommodated without difiicul- .ties in the space available in the cylinder head of the engine. Furthermore, by the use of such guide member, I

Patented Sept. 27, 1960 valve so that any desired control characteristic may be' readily obtained thereby. V

The guide member carrying the control elements is preferably connected with an adjusting member which is adapted to be actuated manually or which is automatically effective and which adjusts the rocker arm and the intermediate lever relative to one another. The manual adjusting member is thereby formed by a threaded spindle operatively connected with .the guide member which threaded spindle cooperates with an adjusting nut member secured at the engine housing. The adjusting arrangement, however, may also be realized automatically by means of a piston adapted to slide within a cylinder and acted on by a suitable pressure medium, the actuating pressure of which is controlled by a control valve member in turn controlled in dependence on the rotational speed of the engine. The control valve member is operatively connected, preferably over an adjusting linkage with a rotational speed indicator, especially with one constructed as centrifugal governor which is preferably operatively connected with the control shaft of the engine. The valve member is carried by the piston rod and is connected by means of pressure hoses with the pump of the hydraulic system. As a result thereof, the pressure oil connection takes place at a structural part of the installation which is moved with relatively large forces so that the disturbing or interfering force caused by the supply of pressure oil doesnot influence the rotational speed indicator.

A simple valve-drive is obtained in accordance with the present invention if the drive of the rocker arm constructed as cam member takes place from a control shaft through the interposition of a push-rod which is form lockingly connected with the means of the control shaft effecting reversal of movement, for example, with a cam or swash plate. The connection of the intermediate lever with the valve may take place by means of a joint which is formed by a ball head of the valve and a cylindrical recess in the intermediatelever. As a result thereof, the assembly is limited to the parts themselves which are to be connected with each other so that no additional ele- 'ments are required therefor. Furthermore, by the use of this type of connection, relatively small pressures occur and the advantage may be obtained that the valve is able to rotate freely. The intermediate lever is constructed as fork with two plane control surfaces inclined with respect to each other at an angle so that a simple manufacture and ready assembly with the other structural parts is assured. V V

The play between the cam surfaces of the rocker arm and the control surfaces of the intermediate lever is adjustable by means of cams or eccentrics arranged coaxially with the respective axes of rotation thereof. A further simplification may be achieved by constructing the camrocker arm with a valve opening curve'or cam portion and a valve closure curve or cam portion in a form adapted to be readily ground or machined by a continuous grinding, polishing or machining operation.

Furthermore, the guide member carrying the cam-type rocker arm and the intermediate lever is adjustably supported in the axis of rotation about a cam which serves for purposes of adjusting the valve spindle.

Accordingly, it is an object of the present invention to provide a valve control arrangement for internal com bustion engines which avoids the disadvantages and short comings of the prior art installations. Another object of the present invention resides in the provision of a valve control arrangement for internal com: bustion engines which is simple in construction, relatively inexpensive in manufacture and assembly, and which obviates the necessity of an overhead cam or control shaft arrangement.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

Figure 1 is an elevational view of a valve control arrangement in accordance with the present invention, partly in cross section, whereby the hydraulic installation for changing the control characteristic is indicated only schematically;

Figure 2 is a top plan view of the valve control arrangement of Figure 1;

Figure 3 is a cross-sectional view, on a larger scale, taken along line IIIIII of Figure 1; and

Figure 4 is a simplified elevational view of a modified embodiment of a valve control arrangement in accordance with the present invention.

Referring now to the drawing, wherein like reference numerals are used throughout the various views to designate like parts, and more particularly to Figures 1 to 3 thereof, reference numeral 1 designates the control or cam shaft which is driven from the internal combustion engine (not shown in detail herein). The drive of control or cam shaft 1 may take place in any suitable manner. The control or cam shaft 1 is thereby provided with a number of cams 2 for the control of the inlet and outlet valves corresponding to the number of engine cylinders. Since the control of each inlet and outlet valve of the internal combustion engine is identical, the control arrangement in accordance with the present invention will be described hereinafter by reference to only a single inlet valve. The push-rod 4, form-lockingly connected with cam 2 over annular portion 3, is pivotally secured with the cam-type rocker arm 6 over a joint 5. The cam-type rocker arm 6 is provided with a valve-lifting cam portion 7 and a valve-closing cam portion 8 which pass over into each other in such a manner that the rocker arm 6 may be made in a shape to be continuously ground. The camtype rocker arm 6 is carried by the interposition of a bolt member 9 on a

guide member

10, 10 which is secured in the cylinder head of the engine by means of

11, 11. An intermediate lever 12 is arranged at the

guide member

10, 10 independently of the cam-type rocker arm 6 which is pivotally supported about a bolt member 13. The intermediate lever 12 is constructed as a fork provided with two

plane control surfaces

14 and 15 inclined with respect to each other at an angle. The control surface 14 abuts against the valve lifting cam portion 7 and the surface 15 against the valve closure portion 8. The end of the intermediate lever 12 disposed opposite the fork terminates in a housing 16 which is provided with a cylindrical bore 17. The ball-shaped head 13 of a valve disk 19 is inserted into the cylindrical bore 17. The

guide member

10, 10 carries coaxial with the axis of rotation 9 of the cam-type rocker arm 6 a bow-shaped member 20 which is operatively connected with an adjusting member formed by a cylinder 21 and piston 22. The piston 22 is operatively connected with a control valve member 24 over piston rod 23. The control valve member 24 is provided with a pressure-oil supply groove 25 and a discharge groove 26. The groove 25 is in communication over a bore 27 with a pressure hose 28 (Figure 3) which in turn is operatively connected with the pump 29 (Figure l) of the hydraulic installation. The discharge groove 26 of the control slide valve 24 is also in communication with a pressure hose 31 over a cross bore which terminates or discharges in the sump, tank or reservoir 32 of the hydraulic installation. The supply groove 25 and the discharge groove 26 may be selectively brought into communication by rotation of the control valve member 24 in the circumferential direction thereof with

lines

33 and 34, respectively, which extend through the piston rod 23. The line 33 thereby terminates in the upper working space of the cylinder 21 above the piston 22 while line 34 terminates in the lower working space of the cylinder 21 below piston 22. The control valve member 24 is operatively connected over a lever 35 with an adjusting linkage 36 which is operatively connected with a centrifugal governor 37. The centrifugal governor 37 is rotated by means of a shaft 38 formed by the internal combustion engine or operatively connected therewith in any suitable manner.

For purposes of the basic adjustment of the control system in accordance with the present invention the required play between the valve 19 and the intermediate lever 12, on the one hand, and between the intermediate lever 12 and the cam-type rocker arm 6, on the other, has to be established. For that purpose, the respective bearing bolt members 9 and 13 and the pivot pins 11, 11' are eccentrically constructed, i.e., as cams, so that rotation of the bolts and pivot pins about the axes thereof effects a displacement of the parts with respect to each other. By raising or lowering the rotational axis of pivot pins 11, 11' of the

guide member

10, 10, the position of the intermediate lever 12 with respect to the ball-head 18 of the valve 19 is thereby corrected in a sense corresponding to the required operating conditions.

During operation of the engine, the push rod 4 is reciprocated by the control shaft 1 whereby the cam-type rocker arm 6 is pivoted about the bolt 9. If the push rod 4 moves downwardly, the the control surface 14 of the intermediate lever 12 glides along the outwardly swinging valve-lifting cam portion 7 whereby the lever 12 pivoted about the respective bearing bolt member 13 effects the opening movement of the valve 19. If the lowest position of the push rod 4 is attained, then a reversal of movement takes place by the earn 2. The camtype rocker arm 6 is now pivoted in the opposite direction by the upwardly-moving push rod 4 whereupon the intermediate lever 12 and therewith the valve 19 is positively returned and closed with the aid of the closure cam portion 8.

If the operating conditions of the engine change as a result, for example, of an increase in the rotational speed thereof, then the control characteristic is automatically adjusted to the optimum condition thereof. If the shaft 38 is rotated then the fly-weights 39 of the control member 37 are forced outwardly by the centrifugal force whereby the adjusting linkage 36 is moved upwardly in the plane of Figure 1 of the drawing and thereby adjusts the lever 35 of the valve member 24. As a result thereof, the pressure oil supplied at first over the auxiliary line 40 and the pressure reducing valve 41 without producing any work now reaches with the aid of the pressure hose 28 the supply groove 25 of the control valve 24. If now by the adjusting movement described hereinabove the lever 35 is pivoted in the counterclockwise direction, then the groove 25 is brought into communication with the line 34 so that the pressure oil enters the lower working chamber of cylinder 21 and the piston 22 also moves up wardly. The supply of oil under pressure is maintained for such length of time until the piston rod 23 again readjusts the slide valve 24 into the horizontal position, however, into an initial position displaced upwardly by an amount corresponding to the adjustment determined by the centrifugal governor, i.e., so that the line 34 gets out of range of groove 25 in a step-like manner. The pressure oil which is present in the upper working space above the piston 22 flows off through line 33 into the discharge groove 26 and is from there conducted over line 30 as well as pressure hose 31 into the sump or reservoir 32. If the piston 22 slides upwardly in the manner described hereinabove, then the guide member 10, 10' which carries the cam-type rocker arm 6 and the intermediate lever 12, is pivoted over the bow-shaped member 20 about the pivot pins 11, 11. As a result thereof, the cam-type rocker arm 6 is adjusted relative to g the intermediate member 12 in such a manner that the stroke of the valve 19 becomes larger. If the rotational speed of the engine is further increased, then the operation described hereinabove is repeated anew until the valve member 24 and therewith the working piston 22 inclusive the guide member 10, pivotally secured thereto are readjusted to the new operating conditions. If the rotational speed of the engine drops, then the centiifugal governor 37 moves the lever 35 in the clockwise direction. As a result thereof, the supply groove 25 is thereby brought into communication with line 33 and the discharge groove 26 with line 34. As a result thereof, the working piston 22 moves downwardly until the horizontal position of the control valve member 24 is reached anew. The valve stroke of valve 19 is thereby correspondingly reduced and simultaneously therewith the commencement of the stroke thereof is correspondingly displaced. The pressure cushion below the piston 22 is reduced over

lines

34, 26, 30 and 31.

. Figure 4 shows a modified embodiment in accordance with the present invention which distinguishes itself from theembodiment described in connection with Figures 1 through 3 by the particular drive of the push-rod as well as by the adjusting member for changing the control characteristics. The same parts in Figure 4 are designated therein with the same though primed reference numerals as used in connection with the embodiment of Figures 1 through 3. g

The cam or control shaft 1' is formed integral with a swash plate 42 in which engages an angle lever or bell crank 43 which is supported at the engine housing in any suitable pivotal manner. A push rod 4' is pivotally secured to the angle lever 43. The push rod 4 isindriving connectionwith the cam-type rocker arm 6 over a joint 5. The rockerarm 6 and the intermediate lever 12' are arranged on a common guide member 10 and are mo'vably supported. independently of each otherabout bolt members 9 and 13' respectively. The pivotal connection of the intermediate lever 12' with the valve 19' takes also place by means of a ball head 18. For purposes of changing the control characteristic, the guide member 10' is provided at the free angularly bent end 44 thereof with a threaded spindle 45 having a relatively large pitch. The spindle 45 cooperates with an adjusting member 46 which is rigidly secured or anchored at the engine housing 47. A detachable actuating member 48 is arranged at the nut member 46. Furthermore, with an internal combustion engine having several cylinders 21 toothed rack or Worm drive 49 indicated in Figure 4 in dot and dash line is operatively connected with the nut member 46 for purposes of simultaneously adjusting all of the valve drives.

If the control or cam shaft 1' and therewith the swash plate 42 rotates, then the push rod 4 is reciprocated by means of the connection with the swash plate 42 over bell crank or angle lever 43. As a result of this reciprocatory movement, the opening and closing of the valve 19 takes place positively over cam-type rocker arm 6' and intermediate lever 12' as described also in connection with the embodiment of Figures 1 through 3. If the internal combustion engine, for example, a stationary engine operating essentially at constant speed is driven within a different operating range, then it is only necessary for purposes of changing the control characteristics to insert the actuating member 48 into the nut member 46. By rotating the same, the guide member 10" is raised or lowered about the pivot pin 11" thereof whereby a displacement of the commencement of the valve stroke, ie, a corresponding correction of the valve time is achieved.

While I have shown two embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of many changes and modifications within the spirit and scope of the present invention. For example, in the place of the cam-type rocker arm an angle lever or bell-crank operatively conne'cted' with the pushrod may be provided the reciprocjatthe adjustment of the control characteristics of the engine may also take place by means of any suitable pneumatic or electrically controlled installation. v

Thus, it is obvious'thatthe present invention is susceptible of many changes and modifications within the spirit and scope of the present invention and, therefore, I do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications-thereof as are encompassed by the scope of the appended claims.

I claim:

.1. A valve control arrangement for an internal combustion engine, particularly for high speed motor vehicle engines in which the opening and closing of each valve is. realized by means of an oscillating rocker arm, comprising rocker arm means, valve means, intermediate lever means having a plurality of control surfaces and operatively connected with said rocker arm means and with said valve means to produce the opening and closing movement of said-valve means by the oscillatory movement of said rocker arm means, ,guide means adjustably arranged at the engine housing, and means movably supporting the control elements consisting of said rocker arm means and said intermediate lever means independently of one another on said guide means. a

2, A valve control arrangement for an internal cornbustion engine according to claim- 1, wherein said rocker arm means is a cam-type rocker arm, and wherein said guide means is adjustably supported about an eccentric pivot member disposed in the axis of rotation thereof to provide thereby adjustment of the valve play.

3. A valve control arrangement for an internal combustion engine with an engine housing, particularly for high speed motor vehicle engines in which the opening and closing of each valve is realized by means of an oscillating rocker arm, comprising rocker arm means, valve means, intermediate lever means having a plurality of control surfaces and operatively connected with said rocker arm means and with said valve means to produce the opening and closing movement of said valve means by the oscillatory movement of said rocker arm means, guide means adjustably mounted at said housing, means supporting the control elements consisting of said rocker arm means and of said intermediate lever means independently of one another at said guide means, and adjusting means operatively connected with said guide means for adjusting said rocker arm means and said intermediate lever means relative to one another.

4. A valve control arrangement for an internal combustion engine according to claim 3, wherein said adjusting means is a manual adjusting means.

5. A valve control arrangement for an internal combustion engine according to claim 3, wherein said adjusting means is an automatic adjusting means.

6. A valve control arrangement for an internal combustion engine according to claim 3, wherein said adjusting means includes a threaded spindle operatively connected with said guide means and an adjusting nut member secured at said engine housing and cooperating with said threaded spindle to provide the adjustment.

7. A valve control arrangement for an internal combustion engine according to claim 3, wherein said adjusting means includes a cylinder and a piston slidingly accommodated within said cylinder and acted on by a pressure medium and control valve means for controlling said pressure medium in dependence on the rotational speed of the engine.

8. A valve control arrangement for an internal combustion engine according to claim 7, further comprising centrifugal governor means operatively conected with said engine, and adjusting linkage means operatively connccting said centrifugal governor with said control valve means.

9. A valve control arrangement for an internal combustion engine according to claim 8, wherein said piston includes a piston rodsupporting thereon said control valve means, a hydraulic installation for supplying the hydraulic medium including a pump and pressure hose means operatively connecting said control valve means with said hydraulic installation.

10. A valve control arrangement for an internal combustion engine, particularly for high speed motor vehicle engines in which the opening and closing of each valve is realized by means of an oscillating rocker arm, comprising cam-type rocker arm means, valve means, intermediate lever means having a plurality of control surfaces and operatively connected withsaid rocker armmeans and with said valve means to produce the opening and closing movement of said valve means by the oscillatory movement of said rocker arm means, a control shaft, a push rod, means on said control shaft to provide reversal of movement ofsaid' push rod during rotation of said con trol shaft, and drive means including said push rod formlockingly connected with said means providing reversal of movement for driving said cam-type rocker arm means from said control shaft.

11. A valve control arrangement for an internal combustion engine according to claim 10, wherein said means providing reversal of movement is an eccentric member.

12. A valve control arrangement for an internal combustion engine according to claim 10, wherein said means providing a reversal of movement is a swash plate.

13. A valve control arrangement for an internal combustion engine, particularly for high speed motor vehicle engines in which the opening and closing of each valve is realized by means of an oscillating rocker arm, comprising rocker arm means, valve means, intermediate lever means having a plurality of control surfaces and operatively connected with said rocker arm means and with said valve means to produce the opening and closing movement of said valve means by the oscillatory movement of said rocker arm means, and joint means. operatively connecting said intermediate lever means with said valve means including a ball head on said valve means and a cylindrical recess in said intermediate lever means for receiving therein said ball head.

14. A valve control arrangement for an internal combustion engine, particularly for high speed motor vehicle engines in which the opening and closing of each valve is realized by means of an oscillating rocker arm, comprising rocker arm means, valve means, intermediate lever means having a plurality of control surfaces and operatively connected with said rocker arm means and with said valve means to produce the opening and closing movement of said valve means by the oscillatory movement of said rocker arm means, said intermediate lever means being constructed as a fork provided with two plane control surfaces inclined with respect to each other at an angle.

15. A valve control arrangement for an internal combustion engine according to claim. 14, wherein said rocker arm means includes a cam having a valve opening and closure cam portion and wherein the play between said cam portions and said control surfaces is adjustable by eccentrics arranged in the respective axes of rotation thereof.

16. A valve control arrangement for an internal combustion engine according to claim 10, wherein said camtype rocker arm means is provided with a valve opening and a valve closure cam portion of such shape as to be readily machined by continuous grinding operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,097,883 Johansson Nov. 2, 1937