JPS5825506A - Valve line means in reciprocal internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to valve trains for internal combustion engines, and more particularly to rocker arm and pivot assemblies for use with such valve trains.

Conventional rocker arm and pivot assemblies, such as those typically used in passenger car-type engine valve trains, such as those used in overhead frame-operated valve trains, are inherently spherical or part-cylindrical to provide a large bearing surface. It includes a pedestal-mounted rocker arm that generally includes a shaped pivot or fulcrum. In such an arrangement, the rocker arm is actually in sliding engagement with respect to its associated fulcrum, and therefore, even if these elements are properly lubricated, this type of arrangement results in loads being applied to the respective bearing surfaces. As a result, it provides a large area of frictional resistance so that heat accumulation occurs.

The desirability of overcoming the above-mentioned problems has been recognized and has therefore resulted in a variety of specially configured or non-pr
A type of rocker arm assembly has been proposed. Such specially constructed or non-generating rocker arm assemblies may be used, for example, in race car engines.
Used in special engine applications. Therefore, in such special engine applications, roller bearing assemblies are used to pivot the rocker arms to reduce friction. Such a roller bearing assembly is mounted on a short shaft fixed to a fulcrum such that it rotatably supports an associated rocker arm in a manner similar to those known in the art (e.g., U.S. Pat. No. 3,621,823). be done.

It is readily apparent that a rocker arm and its associated pivot assembly including such one or more roller bearing assemblies would be much more complex and expensive from a production standpoint for use in a typical passenger car engine.

Additionally, known rocker arm pivot structures (for example, U.S. Pat. No. 14
97,451), it has also been proposed to provide a rocker arm and pivot arrangement in such a way that the rocker arm can be moved in a rolling motion to move the support in a known manner (e.g., U.S. Pat. No. 2,943,612). ing.

This known method (e.g. U.S. Pat. No. 2.943.612)
It will be clear that the rolling contact between the rocker arm and the pivot can be comparable to that of a cylinder rolling on a flat or substantially flat surface. It is well known from standard engineering textbooks that cylinders rolling on flat surfaces produce high operating contact stresses. Thus, known rocker arm and pivot structures (e.g. U.S. Pat. No. 2,943,612)
With cylinders rolling on a flat, yet substantially flat surface, such rocker arrangements reduce the tendency for premature fatigue failure due to the high stresses encountered during engine operation; Possibly requiring the use of more expensive materials. As can be seen, the increased mass now imposed by the rocker arm is detrimental to smooth valve train operation since the increased inertia forces can cause a reduction in valve train performance.

The valve array means of the present invention includes an engine block that defines a cylinder together with a port, a valve that is reciprocatably positioned within the port and biased to a predetermined position, and a valve that is spaced apart from the valve and that reciprocates the valve. a reciprocating internal combustion engine of the type having a valve actuator movable in opposite directions to cause the valve to engage the valve and the valve actuator and actuated during an oscillating movement to bias the valve. valve train means including a rocker arm reciprocating against the engine to open and close said port for engine operation, including means defining a rocking support midway in the length of the rocker arm; and said rocker arm defines a pair of cooperating inner and outer cylindrical bearing surface contours that carry the reaction force of the rocker arm rotational movement, the radius of the outer contour being between 3 and 1.7 of the radius of the inner contour. and includes restraint means for substantially rolling movable anchoring of said cooperating cylindrical profile in relation to said inner profile, said restraint means extending radially outwardly from said inner profile. and a recess in the outer profile sized to receive the pin, the recess flaring outwardly in a direction toward the center of the outer profile to provide an opposing surface over which the bottle is to be walked during rocker swing. forming a sloped guiding surface,
The shape of the bottle is such that the bottle moves substantially in a walking motion during such rocking, and as described above, within the range of rocker arm rocking, the pin is moved by contact with the guide surface of the recess. It is characterized in that it establishes a substantially rolling contact between the cylindrical profiles and itself carries out a substantially rolling contact with the guide surface defined by the recess.

A principal object of the present invention is that an otherwise conventional rocker arm and its fixed fulcrum are substantially R and R2, respectively.
With partially circular concave and convex bearing surfaces preferably having a radial relationship of An object of the present invention is to provide an improved rocker arm and pivot assembly that allows for substantial transfer or walking contact.

It is therefore another object of the invention to have a rocker arm with a semi-cylindrical bearing surface intermediate its ends and its associated pivot having a semi-cylindrical fulcrum bearing surface, the radius ratio of this surface being 3.
=1 to 1.7:1, preferably 2:1. One of said bearing surfaces is provided with a guiding recess or slot sized and shaped to receive in substantial rolling or walking contact a protruding retaining pin provided on the other bearing surface, said slot and retaining The bin is preferably located midway between the arcuate ends of each bearing surface.

Still another object of the present invention is to provide an improved rocker arm and pivot assembly for use in an internal combustion engine valve train that features minimal energy loss during operation, thereby maximizing fuel efficiency. .

Still another object of the invention is to provide a rocker arm and pivot of the type described above that is easy to manufacture, inexpensive, reliable in operation and otherwise suitable for use in production automobile engines.

For a better understanding of the invention and other objects and features, the following detailed description of the invention is provided with reference to the accompanying drawings.

First, referring to Figures 1, 2, and 3,
A portion of a conventional overhead valve internal combustion engine having a cylinder head 10 is shown in the figure. A stem of a poppet valve 12 is slidably guided in the interior bore 11 of the cylinder head so as to be able to reciprocate in the axial direction, and its upper portion projects above the cylinder head. As is conventional, the poppet valve 12 is normally maintained in the closed position by a spring 14 surrounding the top of the stem of the valve 12, with one end of the spring 14 attached to the cylinder head 1o.
and the other end engages a conventional retaining washer assembly 15 secured to the stem of the poppet valve 12 in a conventional manner.

A push rod 16 is reciprocatably disposed within the cylinder head in the lateral direction of the poppet valve 12, and its upper end projects above the cylinder head 1o. As before, push rod 1
The lower end of 6 abuts the upper end of a valve tappet, not shown, which operatively engages a cam on a conventional through-cine camshaft, so that the push rod can be moved by the contour of the cam on the camshaft, not shown. It is made to reciprocate as determined.

A valve catch arm 20 constructed in accordance with the present invention operatively connects the push rod 16 and the poppet valve 12. The rocker arm 2.0 is made of sheet metal, for example, and includes arms 21 and 22 which are mounted above and above the upper ends of the push rod 16 and the poppet valve 12, respectively. As shown, the arm 21 is spherically recessed at 23 on its bottom surface to receive the upper end of the push rod 16 in a socket-like manner.

Between the arms 21 and 22, the rocker arm has an intermediate curved section 24 with a semi-cylindrical concave bearing upper surface 25. As shown, rocker arm 20 is generally U-shaped in cross-section with a web portion formed by arms 21.22 and intermediate section 24, and has integral upright side walls 26 and end walls 27a, 27b.

The bearing surface 25 is a semi-cylindrical concave lower bearing surface 4 which will be described in detail later.
Fixed holed pivot support or fulcrum 40 with 1
They are working together as described below.

The rocker arm 20 has a longitudinally extending hole 28 intermediate its ends and in the center of the intermediate portion 24, best shown in FIG. Extending is a support member having external threads 51 for threadably receiving a threaded nut 52 which is used to hold the fulcrum 40 together when properly secured to the cylindrical head 10. at its free upper end.

As best seen in FIG. 2, in the illustrated embodiment the fulcrum 4o is of rectangular shape and extends longitudinally so that it is connected to the side wall 26 of the rocker arm 2o.
Can be accepted loosely in between. 2, the fulcrum 40 has a flat upper surface 42 for abutting the lower surface of the nut 52 and a central through hole 43 of a suitable diameter.
By having it you can stun F:5o
can be slid freely.

Now, according to one feature of the invention, the bearing surface 25 of the rocker arm 20 is formed with a suitably predetermined radius R, while the bearing surface 41 of the fulcrum 4o is formed with a substantially radius 1/2R. Therefore, when the rocker arm 2o rotates, the bearing surface 41 of the fulcrum 40 and the bearing surface 25 of the rocker M20
Contact with transferee. The relative rolling contact between these bearing surfaces with a radius ratio of 2:1 may be referred to as Cardanian motion.

Cardanian motion is a planar motion in which one circle or cylinder rolls inside another circle or cylinder twice its size without slipping at the points of contact between these elements. Therefore, in the illustrated embodiment of the rocker arm and fulcrum, Cardanian motion is achieved by using a 2:1 ratio of the radii of curvature of these fixed, moving send loads so that the send loads are on the same side of a common tangent. It can be obtained by With this radius ratio of 2:l to obtain Cardanian motion, a point on the circumference of the rolling circle or cylinder lies within a straight line passing through the axis of the rolling circle or cylinder.

In addition, the fulcrum 40 includes a protruding retaining pin 44 depending from the bearing surface 41 and preferably located midway between its ends, as best shown in FIGS. 1 and 2. The retaining pins 44 will therefore extend longitudinally outwardly a predetermined distance from either side of the hole 430, aligned with and perpendicular to the axis of this vertical hole 43. Preferably, therefore, the retaining bins will be located symmetrically with respect to the axis of the stud 50. A protruding retaining pin 44 having a shape similar to a gear tooth and having an appropriate thickness to withstand any side loads encountered in a given engine application is provided with a through taper in the intermediate portion 24 of the rocker arm 20. It is slidably received within a recess or guide slot 29 .

As best shown in FIGS. 1 and 3, the guide slot 29 also preferably extends transversely outside the hole 28, aligned with and perpendicular to the central vertical axis of the hole. It is located midway between the ends of the bearing surface 25.

The width of the guide slot 29 is preselected relative to the width of the retaining pin 44, so that the retaining pin 44 ensures rolling contact of the bearing surface 41 against the bearing surface 25 of the rocker arm 20. operatively slidably received within slot 29. It is also apparent that this arrangement of retaining pin 44 and guide slot 29 operates in response to reciprocating movement of push rod 16 to prevent lateral rotation of the rocker arm perpendicular to the intended plane of rotation. indoor slot 2
9 and the preferred configuration of the cooperating retaining bin 44 are discussed in detail below.

The salient features of this transfer contact rocker and arm pivot can be stated as follows.

The rolling contact consists of (1) the curved bearing surfaces 25 and 41 in rolling contact with each other and (11) the pin 4 of the fulcrum 40 extending into the tapered vertical slot 29 in the rocker arm 20.
This is ensured in combination with the transfer contact which is maintained to a significant degree by guiding 4, and the center of the pin is at the intermediate position of the rocker arm 20, i.e. at the position shown in FIG. Coinciding with the contact point of the curved bearing surface.

The pin-in-slot guide takes advantage of the lost-point nature of the path of the rocker arm and fulcrum bearing surfaces 25.41 contact points to minimize slot clearance and length.

Other embodiments of the rocker arm and fulcrum structure according to the present invention are shown in FIGS. 4, 5 and 6, in which:
Like parts are indicated by like numbers but with an added dash l where appropriate.

In this alternative embodiment, rocker arm 20' also includes arm 21'.
, 22' and the intermediate portion 24'. Figure 4,
As shown in FIGS. 5 and 6, the rocker arm is generally U-shaped in cross-section and has a web portion defined by arms 21'-122' and intermediate portion 24' and has integral upright side walls 26'. ing.

A web portion intermediate the ends of the rocker arm 20' and at the center of the intermediate portion 24' extends longitudinally and includes a dosing hole 28'. On each transverse side of the bore 28', the rocker arm 20' includes a transversely extending rocker means defining a cylindrical bearing surface means 30. In addition, the cylindrical bearing means 30 has retaining pin means 44' extending radially outwardly therefrom.

In the configuration shown in FIGS. 4, 5 and 6, the rocker means includes a pair of transversely spaced rockers formed as separate elements suitably secured to the rocker arm 20'. Defined by pins 31, each rocker pin 31 has a retaining bin 44' also formed as a separate element suitably secured thereto. For this latter purpose, in the configuration shown, each rocker pin 31 extends axially around its outer circumferential surface and extends a predetermined distance from one end of the rocker pin 31 and is fixed to the rocker pin, for example by welding. A slot 32 is configured to receive the foot end of a retaining bin 44'.

Referring again to the configuration shown, each side wall 26' includes a hole 28.
' and sized and shaped to receive the exposed portion of the associated retaining bin 44'; A key-shaped hole defining a slot hole 34 is provided.

'As best shown in Figures 5 and 6,
Each locker bin 31 and associated retaining pin 44' is a locker partially captured within the associated side wall 26'.
At the outer end of the bin 31 a retaining pin 44' is inserted into the associated side wall 26' to locate it. The lock pin 31 and associated retaining pin 44' may then be further secured to the locker arm 20', for example by welding at the interface of these elements with the associated side wall 26'.

The rocker arm has a T-shaped configuration with a vertically extending post 61 section and a fulcrum arm 62 extending outwardly from each side thereof at right angles thereto, as best shown in FIGS. 5 and 6. Associated therewith are fulcrum posts 60 whose combined dimensions are such that the fulcrum arms are slidably received between the side walls 26' of the rocker arms 20'. Also, as shown, the post 61 is sized to extend loosely through the hole 28' in the rocker arm 20'.

Each fulcrum arm 62 has a concave semi-cylindrical bearing surface 63 on its underside for relative rotational locking with the bearing surface means 30 of the locker bin 31. In addition, each fulcrum arm 62 has at its outer or free end a tapered guide slot 29' of a suitable size and shape for slidably receiving a retaining pin 44' of an associated locker bin 31. .

The central hole 64 extends through the fulcrum post 60 so that it can be used, for example, in the cylinder head 1 for this purpose.
A screw 70 is threaded into a suitably internally threaded hole 71 provided at 0'. It will be properly fixed.

Now, to protect against rotation of fulcrum post 60 and rocker arm 20' about the axis of screw 70, and typically not shown, a second rocker arm and associated fulcrum post are placed in spaced apart substantially parallel relationship. Since it is located, it is known (
Retaining members 72 are used with these assemblies in a manner similar to, for example, US Pat. No. 3,198,183.

In the configurations shown in FIGS. 4, 5, and 6, the retaining member 72 is formed to extend between a pair of adjacent screws 70 (only one of which is shown) and is spaced apart from each other. Perforated base 73 and inverted U0-shaped interconnecting web 7
It has 4. Each base 73 is positioned below the head 70a of the screw 70 and is adapted to receive an associated screw 70 for tightening therewith against the associated fulcrum post 60.

Each base 73 has a slotted recess 75 on its lower surface, and each fulcrum post 60 has a corresponding upright boss 65 on its upper end that engages the associated slotted recess 75. The retaining member 72 thus holds the associated fulcrum post relative to one another against rotation about the screw TO.
0 and related fulcrum pillars.

In this alternative embodiment of FIGS. 4, 5 and 6, the ratio of the radius of the bearing surface 63 of the fulcrum arm to the radius of the bearing surface means 30 of the rocker bin 31 is preferably 2:1. .

It is believed that an increase in fuel economy of 1.5 to 2 inches could be obtained in an internal combustion engine if the friction losses in the valve train due to the normal sliding contact between the rocker arm and its associated pivot could be substantially eliminated. It was originally estimated based on calculations. However, FIGS. 4, 5 and 6 constructed in accordance with the present invention
Initial testing of a V-6 engine using a prototype embodiment of a rocker arm and pivot assembly similar to the illustrated embodiment has shown that this performance compared to the operation of the same engine with a conventional rocker arm and pivot assembly. In fact, a 2.1 inch improvement in engine fuel economy was achieved.

Thus, the rolling contact between the rocker arm and the pivot assembly described above provides substantially the same low friction as rolling bearings, but achieves this with a simple and low cost construction. This rolling contact rocker arm and pivot arrangement is substantially similar in general appearance to conventionally produced types of rocker arms and pivots, except for its respective bearing surfaces and associated retaining bin and slot arrangement as shown. It should therefore be clear that the rocker arm and pivot structure according to the invention can be easily replaced with conventional rocker arms and pivots in production engine valve trains or already produced engines, since such replacement This is because it can be easily done without adding any substantial deformation to the engine.

The rolling contact between the rocker arm and pivot of the present invention is comparable to that of a cylinder rolling within a matching cylinder. Such mating contact of one cylinder in rolling contact with the other produces substantially lower operating contact stresses than would occur with a cylinder rolling on a flat or substantially flat surface.

For example, from standard engineering formulas, a cylinder rolling on a flat surface will experience higher working contact stresses that are substantially greater than those that occur in a conforming contact such as that of the rocker arm and fulcrum of the present invention. It has been shown that this occurs. Accordingly, conventional materials of normal gauge, such as those currently used in manufactured rocker arms, can be used in the fabrication of rocker arms constructed in accordance with the present invention.

Cardanian motion is obtained by forming the radii of the bearing surfaces in the preferred configuration R: 1/2 R or 2:1, although this ratio may be varied within given limits if desired. will be clear to those skilled in the art. Thus, for example, if the rocker arm only needs to move a relatively small angular displacement to effect the desired valve-opening movement in a particular engine application, a Cardanian movement with a radius ratio other than 2=1 may be necessary. It becomes possible to obtain a substantial transfer contact performance that is very close to . For example, good results can be obtained by reducing the ratio of these cooperating radii to 1.7:1 or increasing it beyond 2:1, for example to a ratio of 3:1.

However, it should be understood that as the ratio of these radii changes from a 2:1 ratio, the stress load on the rocker arm increases accordingly. Therefore, it will be apparent to those skilled in the art that small deviations from Cardanian displacement motion may be satisfactory in a given engine application as long as the angular displacement of the rocker arm is acceptably small.

Due to the various forces that act on the rocker arm during engine operation, in particular the lateral thrust forces that are applied to the rocker arm due to frictional engagement of the rocker arm with the associated poppet valve 12, etc., stable rocker arm operation is achieved. The guide slot 29 and associated alignment bin should be configured to substantially reduce or completely eliminate sliding movement between the rocker arm and its associated fulcrum due to such forces. There was found.

For this purpose, the guide slot 29 or 29' has a tapered, outwardly flared shape with a preselected apex angle 2ψ as desired, preferably with each of the inclined opposing walls being straight. The surface is shaped to define slots, since such a flat surface is more economical to produce than an endocycloidal guide surface.

Preferably, for a preselected apex angle of the guide slot 29 or 29', the associated alignment bin 44 or 44' follows the envelope or path of the laterally most prominent point of the bin when translated and rotated. are substantially in the shape of a slot and are specifically contoured for any ratio of the radii of the rocker arm and fulcrum bearing surfaces, respectively, so that the bin walks or rolls over the slot during reciprocation of the rocker arm.

7, 8, 9 and 10, the bearing surface 25 or 63 when the rocker arm is pivoted by a preselected angle θmax for a given engine application. The desired pin profile for a given radius ratio of 41 or 30 can be determined analytically or graphically as desired, as detailed below. The embodiment of the rocker arm and pivot assembly of FIGS. 1-3 is used for the purpose of the following description, and includes the rocker arm 20 and fulcrum 40 for this embodiment.
The relevant parts of are shown schematically in their opposite positions. Basically, these elements therefore actually represent a small cylinder or fulcrum bearing surface 44 that rolls inside the outer cylinder or bearing surface 25 of the rocker arm 20, and there is a relative rolling contact between these elements. It is shown to facilitate the visualization of the movements that sometimes occur.

Of course, it should be understood that for the embodiment of FIGS. 4-6, the small cylinder is the bearing surface means 30 on the rocker pin 31 and the outer cylinder is the bearing surface 63 on the fulcrum arm 62.

To design the retaining pin profile, it is first necessary to determine the roll angle θmax of the rocker arm 20 in opening the poppet valve 12 to its maximum lift for the particular engine application. The location of the tapered guide slot 29 in the rocker arm 20 must also be determined. Preferably, as shown, the guide slot 29 is connected to the stud 50.
located symmetrically about the axis of Therefore, the retaining pin 44 is also positioned symmetrically with respect to the stud axis.

As best shown in FIGS. 7 and 8, the width of the tapered guide slot 29 adjacent the bearing surface 25, and thus the half-width τ, is the same for a given engine application as the retaining pin 44. The thickness is preselected to provide the desired structural strength.

In addition, said width, and therefore half-width τ, must also be large enough to extend beyond the extreme contact points El and E2 of the rocker arm and the fulcrum during a given pivoting movement of the rocker arm relative to the fulcrum, as shown in FIG. .

In fact, in addition to the above parameters, and referring to FIGS. 7 to 9, the apex angle of the tapered slot 29 and therefore the half apex angle ψ of this slot on the guiding surface defining the guide slot 29 is It must be preselected to reduce relative sliding of the retaining pin 44 and to facilitate fabrication of this tapered guide slot. For this latter purpose, and again for the embodiment of FIGS. 1-3, the apex angle is preferably relative to the thickness of the curved portion 24 of the rocker arm 20 so that this guide slot is formed as a through slot. is selected.

As shown in FIG. 8, the basic principle for calculating the retaining bin profile is that the line joining the contact point C between the bearing surfaces with the restraint point S on the opposite side of the guide slot 29 is placed on the guide surface as shown. It depends that it should be perpendicular to. The rolling contact point C on the rocker arm 20 is the instantaneous center of rotation of the fulcrum 40 (transfer cylinder) and the retaining pin 4
Since point S on 4 is part of fulcrum 40 (transfer cylinder), the instantaneous velocity of point S must be perpendicular to line CS.

The desired holding bin profile can then be calculated analytically as follows with reference to FIG. 8 and the basic principles described above.

It is now assumed that the rocker arm 20 is fixed, but that the fulcrum 40, ie, the fulcrum bearing surface 41 of the transfer cylinder, rolls thereon. In this case as well, we start from a state in which the fulcrum or transfer cylinder is in a symmetrical position, but in this same position the rocker arm actually moves at an angle θmax from the valve fully closed position.
It rotates by /2.

In this symmetrical position, the surface 25 of the rocker arm 20
Let the upper contact point be Qr, and the contact point on the surface 41 of the fulcrum 40. . shall be. These image points therefore move apart when the fulcrum or transfer cylinder begins to roll. The fulcrum or shifting cylinder is then shifted clockwise by an angle θ. It can be seen that the contact point on the rocker arm has moved to point C at that time.

It is therefore necessary to place a restraint point S between the retaining pin and the wall of the guide slot by drawing a perpendicular line from C to the right side of the tapered guide with respect to FIG. Point S is also a point on the retaining pin profile for a given rotational position.

The distance or length d from the contact point C to the point S along a line perpendicular to the facing surface of the guide slot 29 varies according to the amount of displacement or walking movement.

Therefore, the entire retaining pin profile is obtained by calculating d or distance CS as a function of rotation θ. This can be easily shown as follows.

d= (NRrCglrr, , + (11 items) −ψ
]+τ) resistance where d=length C5 N=radius ratio of restrainer and transfer cylinder (>1) R=radius of curvature of transfer cylinder ψ=half apex angle of guide τ=half width of tapered guide. See Figures 7 and 8.

For example, by substituting various values of degrees of angle θ from 0 to θmax/2 every 10 minutes, d, that is, length CS
For example, in FIG.
The desired working profile for the right side of 4 can be obtained.

Therefore, if the rocker arm swings at an arc θmax of 16°, then θrrax/2 will be 8°.
Using the 0 minute method, a sufficient number of points can be calculated on the retaining pin profile to give the required working profile. Of course, the outline of the side of the holding pin is the same, but they are in opposing shapes.

Referring again to FIG. 7, the crest of the retaining pin connecting the opposing working contours or surfaces of the retaining pin may be selected as desired. Similarly, the fillet profile connecting the working surface of the retaining pin 44 to the bearing surface 41 of the fulcrum may be selected as desired.

It will be clear to those skilled in the art that the above equation for the retaining pin profile can be rewritten in polar coordinates in a known manner.

The equations described above for the design of the retaining pin profile are preferably good for typical Ns in the range of 3 to 1.7 as described above. However, in the preferred embodiment, and (N
=2, ie for Cardanian motion, there is a special property that the contour is very simplified.

Moreover, as will be explained below, this same property makes contour synthesis straightforward without the need for numerical calculations or tedious graphical tracking.

As mentioned above, for a ratio of N=2, the shifting cylinder has a shifting motion called Cardanian motion. Therefore, as shown in FIG. 9, it can be shown that the fulcrum 40, that is, any point p on the circumference of the rolling cylinder, traces a straight line passing through the center of curvature Or of the rocker arm 20, that is, the outer cylinder. A discussion of how this kinematic characteristic is useful in pin profile design follows.

Referring again to FIG. 9, from contact point C, guide g- intersects the guide at S and intersects the transfer cylinder at p.
Draw a line perpendicular to the surface of g. As explained in the previous section, as the transfer cylinder rolls counterclockwise in this figure on the rocker arm 20, the point p moves in a straight line passing through the point Or, which is the center of curvature of the bearing surface 25 of the rocker arm.

Now, from elementary geometry, <CPOr is 90° and PS
dg-glc vertical vertical tear number, point P along PO,
The line of movement of is parallel to the straight guide gg.

The pin attached to the transfer cylinder or fulcrum 40 has a length p and a radius of curvature equal to s with p as the center of curvature. Then, as can be seen from FIG. 9, since p moves along pp' parallel to the guide gg, the pin is always in contact with the guide. A combination of displacement and some sliding occurs at the point of restraint between the pin and the guide. Since the active arc ee of the pin profile is circular, it is easy to design. The radius of curvature of the pin can be expressed as:

For various reasons, such as sudden shocks to the engine or pushrod, there is a constraint between the pin and its guide such that there is one point of restraint on each side of the pin. It is desirable to design the pin's profile so that there are two points of contact. Such two point restraint, as obtained in the preferred embodiment when the radius ratio is substantially 2:1, ensures that the rocker arm is constrained to roll throughout its motion. To achieve such a design, the extreme contact points of the transfer cylinder on the restraint should be 2 widths of the tapered guide as described above.
must exist within τ.

Below is a step-by-step procedure for designing such a pin profile for N=2.

■. Set the transfer cylinder on the line of symmetry of the taper guide. In this position, confirm that the rocker arm has rolled by an angle θmix/2 from the valve fully closed position. This initial geometry places the extreme contact points on the constraint equidistant from, but on either side of, the line of symmetry. It is then necessary to determine that these extreme contact points lie within the width of the tapered guide 29.

2. Then draw from the contact point C a line perpendicular to the right straight surface of the tapered guide gg with respect to FIG. 9 and intersecting the guide at point S and the transfer circle at point P.

3. Using point P as the center of curvature and distance ps as the radius, draw an arc long enough to cover the entire active arc into contact with the guide.

4. Repeat the same procedure for the other side of the pin.

Both of these arcs should be symmetrical about the taper guide line of symmetry.

Referring now to FIG. 10, the geometry after the transfer cylinder has rolled by an angle θ from its symmetrical position is shown for N=2. In that case, (Co Q = θ C By applying the Naori-Rudan principle, the point Q
and O are collinear. Since PO is parallel to the straight guide, (POQ
= ψ C Therefore, <poc=ψ-θ ψ> θ The distance pc is given by the following equation.

PC=2Rstn(ψ-θ) because OC is equal to 2R and the angle cpo is r
r
This is because it is a right angle.

From the above formula, PS = ZRghtψ ten τ range ψ Therefore, 5 = PS - PC = 2Rmψ - 2RrshI (ψ - θ) ten τ□□□ψ = 2
Rrsinψ+2Rrlihl(θ-ψ)+τhouseψThe above equation is used to calculate d, which shows that this circular contour is obtained only when the curvature ratio is equal to 2, that is, the radius ratio is 2:1. It can be seen that the formula is the same as that obtained by substituting N=2 into the previously defined formula that is greater than 2.

Therefore, when the radius ratio is substantially 2:1, the retaining pin 4
the contoured working surface of 4 is of semi-circular contour;
Therefore, on the flat guiding surfaces provided by the guiding slots 29, a shifting movement of these surfaces is obtained. In addition,
In this arrangement, there is no substantial risk of rocker arm slippage between the retaining pin 44 and the retaining pin 44 since the tapered flat surface defining the guide slot 29 imposes a two-point restraint on the alignment pin 44.

Referring now to FIG. 11, one embodiment of a preferred guide slot 29 and retention bin 44 configuration for a reservoir of the type shown in FIGS. It is shown. In this particular embodiment, the fulcrum bearing surface 41 of the fulcrum 40 has a radius of curvature of 6 degrees to the bearing surface 25 of the rocker arm 20.
has a radius of curvature of 12 mm. The radius ratio of these bearing surfaces is therefore 2:1.

In this particular example, θmax=17°-30
', so θmax/'2 = 8°-45'.

The apex angle of the guide slot 29 was 50°, so the half apex angle of the guide was ψ=25°. The radius of curvature R of the transfer cylinder, that is, the fulcrum bearing surface is 611 Im, the half width τ of the tapered guide slot is approximately 3.75 mm, and the holding bottle 44 is approximately 6.6 mm.
ytrm width. The radius of curvature p of the retaining pin 44 in this embodiment is 7 in two places to give the pin a right and left semi-circular working profile.
．． The length was 87 mm, and the pin height was approximately 31 RN. This configuration of retaining bin 44 causes each of its working contours to contact an associated one of the opposed inclined surfaces defining guide slot 29 .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a portion of an internal combustion engine having a valve train incorporating a rocker arm and a fulcrum according to a first embodiment of the present invention, with the rocker arm shown in its mid-rocker position; Figure 2 is a longitudinal cross-sectional view of the rocker arm and fulcrum of the assembly shown in Figure 1 taken along line 2-2 in Figure 1; FIG. 4 is a plan view of the rocker arm itself of the assembly shown in FIG. 4; and FIG. 5 is a cross-sectional view of the assembly of FIG. 4 taken along line 5--5 of FIG. 41; FIG. 6 is a cross-sectional view of the assembly of FIG. Exploded perspective view, FIG. 7 is an inverted, enlarged graphical illustration of a preferred embodiment of a tapered guide and retaining bin itself for use in a rocker arm and fulcrum constructed in accordance with the present invention, with the guide and retaining bins being attached to one another. Figure 8 is an inverted enlarged graph showing how the retaining pin profile of Figure 4 can be determined analytically; Figures 9 and 10 are the rocker arm and an inverted enlarged graph showing how the retaining pin profile can be determined graphically when the radius to fulcrum ratio is substantially 2:1; FIG. 11 is a portion of the rocker arm and associated fulcrum; FIG. 3 is an enlarged fragmentary cross-sectional view of the rocker arm and fulcrum reservoir guide slots and retaining bins of FIGS. be. [Explanation of symbols of main parts] 12... Poppet valve 16... Push rod 20; 20'... Rocker arm 24'... Intermediate portion of rocker arm 20' 25... Concave bearing surface 26' ... Side wall 28'... Hole 29; 29'... Recess 30... Cylindrical bearing surface means 31... Rocker pin 40... Fulcrum 41... Concave bearing surface 50... Stud 60...Fulcrum column 61...Column 63...Concave semi-cylindrical bearing surface Continued from page 1 Priority claim @March 10, 1982 ■United States (US)■
356926 0 Inventor Meng San Chu 205 Abt 42215 Purfside Circle Sterling Heights, Michigan 48078 United States

Claims (1)

[Scope of Claims] I An engine block defining a cylinder with a port, a valve (e.g. 12) reciprocatably positioned within the port and biased to a predetermined position, and a valve spaced apart from the valve. Valve train means in a reciprocating internal combustion engine of the type having a valve actuator (e.g. 16) movable in opposite directions for reciprocating the valve, said valve train means engaging said valve and valve actuator during an oscillating movement. valve train means for engaging a rocker arm (e.g. 20:20') which is actuated to cause said valve to reciprocate against said bias to open and close said port for engine operation; means defining a rocking support intermediate the length of (e.g. 40:
60), said means and said rocker arm having a pair of cooperating inner sides (60) which carry the reaction force of the rocker arm rotational movement.
41:30) and an outer (e.g. 25:63) cylindrical bearing surface contour, the radius of the outer contour being in the range 3 to 1.7 times the radius of the inner contour; Restraint means are provided for substantially rollably mooring the profiles in relation to each other, the restraint means including pins (e.g. 44:44') extending radially outwardly from the inner profile. The outer profile has a recess (e.g. 29:29') sized to receive the bottle, the recess (e.g. 29:29') frescing outwardly in a direction toward the center of the outer profile and forming a rocker arm. defining opposed inclined guide surfaces on which the pin walks during rocking, the configuration of the bin being such that the pin moves in a substantially walking motion when rocking; , within a large range of rocker arm oscillation, said bin (e.g. 44:44') is shaped by said cylindrical profile (e.g. -25,
41; 30.63) and which itself carries out a substantial transfer contact with the guiding surface defined by said recess (29:29'). Column means. 2. The valve array means of claim 1, wherein the radius of the outer profile (e.g. 25.63) is substantially twice the radius of the inner profile (e.g. 41:30); For example, the contact surface of 44.44') has a semi-circular contour so that the bottle moves in a substantially walking motion upon such rocking in substantially two-point contact with the opposed inclined guide surface. Features a valve train means. 3. The valve array means according to claim 1 or 2, wherein the rocker arm (for example, 20) has one end thereof interlocked with the valve (for example, 12), and the rocker arm and both ends thereof an intermediate interlocking fulcrum (e.g. 40') fixed to the engine block and having a portion extending through both the rocker arm and the fulcrum to hold these elements stationary relative to each other; means (e.g. 50
), wherein said fulcrum (e.g. 40) is provided with a convex semi-cylindrical fulcrum bearing surface (e.g. 41).
, the fulcrum is four times the fulcrum bearing surface (e.g. 41
), and the rocker arm (e.g. 20) has a concave semi-cylindrical bearing sleeve [1i'i (e.g. 25
), the bearing surface (e.g. 25) includes a recess forming the guide recess and the bearing surface (e.g. 44)
) and defining said pair of opposed inclined guide surfaces for operative engagement by said bin (e.g. 44). 4. The valve train means according to claim 1 or 2, which is provided with a fulcrum means (e.g. 60) interlocked with the rocker arm (e.g. 20'), which is fixed to the engine block and partially The rocker arm (for example 20') and the front W
e said rocker arm (e.g. 20') is provided with retaining means (e.g. 61) penetrating both said rocker arm (e.g. 20') and said fulcrum means (e.g. extending upwardly from longitudinally opposite sides of the base (e.g. 241) with holes (e.g. 28') therethrough, the holes being located midway between the ends of the base. a semi-cylindrical bearing positioned and sized to operatively receive said retaining means (e.g. 61) and extending transversely between said flanges (e.g. 26') towards said hole (e.g. 28'); A pair of fixed opposing [and cylindrical rocker members (e.g. 31) are provided defining surfaces (e.g. 30), each of said bearing surfaces then extending radially outwardly from said bin (e.g. 44'), said support means (e.g. 60) including a semi-cylindrical fulcrum surface (e.g. 63) of substantially uniform radius engaging said bearing surface of said rocker member (e.g. 31). , said fulcrum means further comprising opposed inclined guide surfaces extending in a direction parallel to the axis of said fulcrum surface (e.g. 63) midway between its ends so as to operatively receive said respective bin (e.g. 44'). Valve train means characterized in that it includes a pair of guide slots (eg 29') defining a pair of said guide recesses. In the valve train means according to any one of the above claims, the recess (for example, 29.29') is arranged in a lateral direction between the bearing surfaces (for example, 41.25:30.63) when the rocker arm swings. defining an inwardly inclined guide surface flared to such an extent as to substantially define an envelope of the most prominent rolling contact point, said pin (e.g. 44:44') such that during such rocking its contact surface characterized in that it has opposed convex actuating surfaces contoured such that said pin (eg 44:44') remains in said recess (eg 29:29') in substantial dislocation with the guide surface. Valve train means. 6. In the valve train means according to any one of claims 1 to 4, the recess (for example, 29:29) is formed on the bearing surface (for example, 41, 25:30.
63) defining opposed inclined guide surfaces flared to such an extent as to define substantially an envelope of the laterally most prominent rolling contact point between said pins (e.g. 44:44'); having opposing working surfaces located symmetrically with respect to a line of symmetry passing through the center of curvature of the bearing surface (e.g. 41:30);
Each contact surface has a center of curvature at the inner bearing surface (e.g. 41.63) with the outer bearing surface (e.g. 25.63) on the opposite side of the line of symmetry during transfer engagement between the bearing surfaces.
30) Valve row hand hole characterized by consisting of a circular arc existing on the contact point of