Guide Device For Multivalve-actuating Bridge For An Internal Combustion Engine

Abstract

In the valve mechanism for internal combustion engines, with each rocker arm actuating two or more valves through a bridge, a device for guiding the bridge comprising a flange rigidly fixed to a guide rod for guiding the bridge, said flange being mounted in a readily removable manner on the cylinder head and secured thereto by utilizing members of the valve mechanism.

Description

This invention relates to a valve mechanism for an internal combustion engine of the type having a rocker arm pivotally mounted on a rocker shaft, a cylinder head, a guide rod mounted on the cylinder head, a bridge having arms and slidably mounted on the guide rod so as to be urged by the movement of the rocker arm, a plurality of valves each stem of which is connected with respective arm of the bridge, said stem being urged downwardly by the movement of the bridge and upwardly by a valve spring through a guide sleeve fixed to and passed through the cylinder head. More specifically the present invention concerns a guide device for guiding the up-and-down movement of the bridge in such a valve mechanism.

In the internal combustion engines of the type described herein, the valve stem is connected with the arm of the bridge capable of moving up and down vertically along the guide rod, and the rocking motion of the rocker arm is transmitted to said bridge to similarly move the valve stems in order to open and close the respective ports in the combustion chamber.

If the guide rod should be improperly positioned when assembling the engine or if loose motion should develop in the movement of the bridge during service, the valve stems would move erratically and thus would interfere with the proper valve timing. It is therefore highly essential that the guide device is to be so designed as to prevent occurrence of such erratic bridge movement and that utmost care should be exercised in installing the bridge guiding members.

The internal combustion engine construction is generally such that the guide rods must be mounted on the cylinder head. In conventional guide devices, guide rods are either force or press fitted directly into the cylinder head or rigidly fitted to flanges and secured by welding, bolting or likewise jointing the flanges to the cylinder head.

Where the guide rod is designed for direct press fitting, the fitting or mating parts must be machined to much closer tolerances and this requirement calls for stricter dimensional control in manufacturing. Moreover, such a direct press fitted connection is liable, in the course of service, to develop rattle and resultant water leakage because the connection is subject to large stresses necessarily set up therein during operation. When a rattling condition has developed in the guide device, the cylinder head must be immediately be replaced or a secondary mechanical trouble may develop to damage the engine beyond repair. In either case, replacement of a guide rod that has worn down to the limit due to sliding guide action entails a cumbersome and often complicated procedure.

In order to avoid the above-mentioned drawback of conventional guide devices, I propose to hold down the flange, with which the guide rod is rigidly connected, to the cylinder head by manner that is basically different from the conventional manners, that is without using an exclusive means of securing the flange direct to the cylinder head.

According to a feature of this invention, a flange rigidly fixed to or integrally formed with the lower end of the guide rod has holes for passing the guide sleeve in which valve stem reciprocates guidedly and a shoulder is formed on the upper portion of the guide sleeve, said flange being rested on the cylinder head and fastened by the shoulders of the guide sleeves when the latter is fixed in place in the cylinder head.

According to a further feature of this invention, a flange rigidly fixed to or integrally formed with the lower end of the guide rod has holes for passing the guide sleeve, said flange having annular boss around each hole and being provided with a seat for the spring around the boss, and said flange being rested on the cylinder head and fastened thereto only by the action of the valve spring. Therefore the action of the valve spring is utilized to push down on the flange to hold it against the cylinder head.

Even where a flange according to this invention is used as a means of securing the guide rod to the cylinder head, strict dimensional accuracy is no less required, and added caution has to be exercised, at the time of securing the flange to the cylinder head, to preserve the original shapes of various related parts. Furthermore, the guide device to secured to the cylinder head is not free from the drawback mentioned above.

To illustrate this invention in detail, attention is directed to the embodiments thereof shown in the attached drawings, in which:

FIG. 1 is a side view mainly in section of a portion of an internal combustion engine according to an embodiment of this invention, showing a guide device as mounted in place;

FIG. 2 is a perspective view of a flange and a guide rod according to the invention, having a recessed seat with a hole at each flange end;

FIG. 3 is a view similar to FIG. 2, showing a modification of the embodiment of FIG. 2;

FIG. 4 is a view similar to FIG. 2, showing another modification of the embodiment of FIG. 2;

FIG. 5 is a side view in section, exemplifying a manner of securing to the cylinder head the flange shown in FIGS. 3 or 4;

FIG. 6 is a view similar to FIG. 5, illustrating a manner of locating the guide rod with respect to associated parts according to the invention.

FIG. 7 is a side view mainly in section of a portion of an internal combustion engine according to another embodiment of the present invention.

FIG. 8 is a perspective view of a flange and a guide rod similar to those of FIG. 2 but constituting another embodiment of the invention, having an annular boss around the hole in each seat portion of the flange; and

FIG. 9 is a view similar to FIG. 6, showing a manner of mounting the flange shown in FIG. 8 on the cylinder head.

Similar numerals refer to similar parts throughout the several drawings.

Referring to FIG. 1, a rocker arm 1 is pivotally mounted on a rocker shaft 2 and is capable of rocking motion around the axis of the shaft 2 as actuated by a push rod 3 in a well known manner. In the shown embodiment of internal combustion engine, two generally identical valves 4 and 4' are employed for each rocker arm. A bridge 5 whose ends are in the form of arms 6 and 6', moves vertically on a guide rod 7 as guided therewith and actuated by rocker arm 1, said guide rod 7 being located on a cylinder head 8 by a flange 9 as will be described more clearly. A valve stem 10, adjustably connected with arm 6 by means of bolt 11 threaded into said arm 6 and locked with nut 12 threaded to said bolt 11 in such a manner as to provide freedom of adjustment, extends slidably in the guide sleeve 13, which is press fitted in and passes through the cylinder head 8, so that, as the stem 10 is caused to reciprocate in said sleeve 13 by the rocking action of the rocker arm 5 a valve disc 14 seats on and unseats from the valve seat 15 to close and open a port formed in a cylinder 23. The guide sleeve 13 is provided at it top end with a valve stem seal 35 in usual manner. Near a stem end 16, where bolt 11 is threadedly engaged with the arm 6, there is provided on the stem a groove 17 for fittedly receiving a conical split key 18, around which is wedgedly secured an upper seat 19 for a valve spring 20. This spring 20 will urge the valve 4 toward its seated position.

In the cylinder head 8, an exhaust gas passage 21 and cooling water passage 22 are formed, as well-known techniques. The other valve 41', whose stem 10' is connected as above with the other arm 6', is associated with parts corresponding to those already mentioned of the valve 4, and such corresponding parts are referred to by like numerals with a superscribed prime sign ('). The valve mechanism arrangement thus far described is conventional and comes under the techniques of prior arts.

According to an embodiment of the invention as shown in FIG. 1, the flange 9 is held down in place by shoulders 24 and 24' integrally formed of guide sleeves 13 and 13' respectively, each sleeve being press fitted into the cylinder head 8 and, if desired, secured further to the cylinder head 8 by threading nut 25 to a threaded lower end portion 26 of said sleeve protruding inwardly from the head 8, as shown in the drawing, so that each shoulder 24 fastens the flange 9 to the head 8.

The bottom end of the guide rod 7 is rigidly fitted to and restrained in the flange 9. Welding or press fit or threaded connection, or any combination thereof, for example, can be adopted for securing rod 7 to flange 9; or the rod 7 and flange 9 may be formed integral, as desired, by machining a single-piece stock.

FIGS. 2 through 6, inclusive, each show a guide device of the invention, consisting of the guide rod and the flange. In FIG. 2, the flange 9 has its both ends recessed to present two seats 27 for the shoulders 24 to rest on and is provided with a centrally positioned hole 28 in each seat 27 for passing guide sleeve 13.

In FIG. 3 wherein respective parts are distinguished by adding a subscript letter a to each reference numeral, as necessary, the flange 9a as a whole is in the shape of letter T, with an arm 29 extending from its midsection in the plane of the flange. The arm 29 has a centrally positioned hole 30 for passing a bolt 31, which is threaded into the cylinder head 8 to secure said flange direct to the head 8 as an additional securing means.

In FIG. 4 wherein respective parts are distinguished by adding a subscript letter b to each reference numeral, as necessary, the flange 9b as a whole is in the shape of a cross, with two arms 29b extending from the midsection in opposite directions, each arm 29b being similarly provided with a centrally positioned hole 30b, as in FIG. 3, for the purpose of securing flange 9b additionally and direct to cylinder head 8 by means of bolts 31, as will be seen in the view in section of FIG. 5. It must be pointed out here that the bolts 31 are auxiliary members for the flanges of FIGS. 3 and 4.

In FIG. 6, the guide rod 7 protrudes downwardly from the flange 9, the protruding portion being indicated at 32 and fittedly received by a recess 33 provided in cylinder head 8. The protrusion 32 and the recess 33 in the head 8 jointly serve as a means of accurately locating guide rod 7 in positional relationship to associated parts.

In FIG. 7, there is shown another embodiment of this invention, wherein corresponding parts are indicated by same reference numerals as in FIG. 1. The illustrated embodiment is substantially same as the embodiment shown in FIG. 1 except that the guide sleeve 13 has no shoulder 24. Therefore, the flange 9 of this device is fixed on the cylinder by only the action of the spring 20 inserted between the seat 27 on the flange 9 and upper seat 19. In another words, the bottom ends of the valve springs 20 are borne by the flange 9 to hold said flange against the cylinder head 8 by its spring action. The flange 9 used in this embodiment is shown in FIG. 8.

Referring to FIG. 8, which illustrates another modification of the flange for mounting the guide rod on the cylinder head, the flange 9 is similar to that of FIG. 2, but the difference being that each seat 27 with the hole 28 has an annular boss 34 forming an upward extension of said hole 28 by its inside diameter, its outside diameter being sized to fit into and thereby restrict the bottom end of the valve spring 20 in lateral direction, such that the flange 9 is pressed down equally at its recessed seat ends against cylinder head 8.

The guide rod 7 shown in FIG. 8 may also protrude downwardly from the flange 9 as illustrated in FIG. 6. Such a device is shown in FIG. 9.

From the foregoing disclosure it will be readily seen that the flange, with which the guide rod is integrally or rigidly connected, is neither welded, threaded nor otherwise jointed to the cylinder head, so that the drawback attendant on such a manner of jointing is eliminated and that the device can be easily removed to facilitate valve mechanism servicing. Furthermore, the force necessary for securing the flange to the cylinder head is obtained not by additional parts but by slightly modified regular members of the valve mechanism; and the flange and guide rod can be accurately located at the time of engine assembly as determined by the guide sleeves and/or the protruding end of the guide rod.

Thus, the guide devices according to the invention are easy to machine and fabricate and thereby improve engine production. I experimentally used the disclosed guide devices in actual engines only to find that they are all effective in accomplishing the stated object and also ensuring the satisfactory and stable performance of the valves.

It is to be understood that this invention is not limited to the exact construction shown and described, but that various changes and modification may be made without departing from the spirit and scope of this invention as defined by the appended claims.

Claims

What is claimed is:

1. A guide device for guiding movement of a multivalve actuating bridge in an internal combustion engine of the type having a cylinder head, a pair of valves including stems slidably received through guide sleeves fitted into the cylinder head, and means for reciprocating said valve stems including a bridge being slidable on a guide rod and having a pair of arms for respectively sliding the valve stems through said guide sleeves: the guide device including a flange resting on the cylinder head and having a pair of apertures respectively receiving said valve guide sleeves, said guide rod rigidly connected to said flange and projecting upwardly therefrom, and releasable means including threads on the lower ends of said guide sleeves and nuts respectively engaged on said threads.

2. A guide device for guiding movement of a multivalve actuating bridge in an internal combustion engine of the type having a cylinder head, a pair of valves including stems slidably received through the cylinder head, and means for reciprocating said valve stems including a bridge having a pair of arms for respectively sliding the stem; the guide device including a removable flange resting on the cylinder head and having a pair of apertures respectively receiving said valve stems, a guide rod rigidly connected to said flange and projecting upwardly therefrom with said bridge being slidable on said guide rod, and removable means engaged on said flange for maintaining said flange on said cylinder head against movement, said cylinder head having a locating recess on the top surface thereof, and said guide rod projecting through said flange and received in said locating recess.