US3138038A

US3138038A - Fuel-injection adjusting device

Info

Publication number: US3138038A
Application number: US170156A
Authority: US
Inventors: Hans O Scherenberg; Gassmann Johannes
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1960-03-11
Filing date: 1962-01-31
Publication date: 1964-06-23
Anticipated expiration: 1981-06-23

Description

J1me 1964 H. o. SCHERENBERG ETAL ,0

FUEL-INJECTION ADJUSTING DEVICE Original Filed March 11. 1560 ATTORNEYS United States Patent 3,138,038 FUEL-INJECTION ADJUSTING DEVICE Hans 0. Scherenberg, Stuttgart-Heumaden, and Johannes Gassmann, Altbach (Neckar), Germany, assignors to Daimler-Benz Alrtiengesellschaft, Stuttgart-Unterturkheirn, Germany Original application Mar. 11, 1960, Ser. No. 14,317, now Patent No. 3,040,723, dated June 26, 1962. Divided and this application Jan. 31, 1962, Ser. No. 170,156 Claims priority, application Germany Mar. 19, 1959 Claims. (Cl. 74-569) This application is a division of applicants prior application Serial No. 14,317, filed March 11, 1960, entitled Fuel Injection Adjusting Device, now Patent No. 3,040,723.

The present invention relates to an adjusting installation for adjusting the time of the point of injection for injection pumps provided with a drive means in the form of a camshaft and a tappet for internal combustion engmes.

The present invention aims at a structural simplification of an adjusting installation for adjusting the time of the injection point of the type mentioned hereinabove and to render the same less expensive as well as to increase the reliability of operation thereof.

The present invention is particularly intended for engine constructions in which the camshaft and the engine control shaft form an integral part.

The present invention essentially consists in arranging the tappet guide means so as to be movable, preferably, rectangularly in relation to the camshaft. In connection therewith, provision may be made so as to render the tappet movable and adjustable essentially rectangularly with respect to the camshaft axes by means of a toothed rack of a worm drive or the like within a predetermined range into any desired positions.

The following structural basic concepts for the construction of the tappet guide arrangement in accordance with the present invention have proved themselves as particularly appropriate:

On the one hand, the tappet guidance may be arranged within an eccentric bushing which is adapted to be rotated, preferably over a gear rim and toothed rack connection. On the other, the entire tappet guide arrangement may be adapted to be pivoted preferably about an axis disposed essentially paralled to the camshaft axis.

In order to attain, with a pivotal tappet guide means, a loading of the upper tappet end which is as satisfactory and unobjectionable as possible, and in order to attain a simple bearing support of the structural parts constituting effectively the pivot axis, the pivot axis in accordance with the present invention is advantageously located at the upper end or within the region of the upper end of the tappet.

For purposes of transmitting the control magnitude to the lower parts of the tappet which are operatively connected with the cam, the pivotal movement may take place in an advantageous manner by means of an arm preferably forming simultaneously the bushing guide means which is acted upon by a rotatable eccentric, cam or the like and by a lever operatively connected therewith.

Accordingly, it is an object of the present invention to provide an adjusting mechanism for selectively adjusting the timing point of injection for a fuel injection system, especially for internal combustion engines, which obviates the disadvantages of the prior art devices.

It is another object of the present invention to provide an adjusting mechanism for adjusting the timing of the injection point of an injection pump provided with a cam shaft drive means and a tappet which considerably reduces the number of parts necessary in the device, is

3,138,038 Patented June 23, 1964 simpler in construction as well as less expensive in manufacture and assembly.

Still another object of the present invention resides in the provision of an adjusting mechanism of the type described hereinabove for selectively adjusting the timing of the injection point which increases the operational reliability thereof.

Another object of the present invention is the provision of an adjusting mechanism for adjusting the timing of the injection point of a fuel injection pump which is provided with a cam-driven tappet or plunger in which the forces and stresses particularly in the tappet end and the part operatively connected therewith are advantageously distributed to avoid any peak stresses.

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 a crosssectional view through a first embodiment of an adjusting mechanism in accordance with the present invention and, more particularly, through the tappet guide means thereof provided with an eccentric bushing, and

FIGURE 2 is a cross-sectional view through a modified embodiment of an adjusting mechanism in accordance with the present invention provided with a tappet guide means having a pivotal arm.

Referring now to the drawing, wherein like reference numerals are used throughout the two views to designate like parts,

FTGURES

1 and 2 illustrate a tappet drive arrangement which consists of a cam 1 and of a roller member 2 normally riding along the cam surface of cam 1. As the cam 1 rotates in the direction of arrow 3, the roller member 2 follows along the surface 4 of cam 1, as is well known.

The roller member 2 is arranged at the lower end of the tappet 5 which is adapted to reciprocate in the upward and downward directions corresponding to the double arrow 6, and more particularly, which is adapted to carry out such reciprocatory movements with the aid of or in opposition to the force exerted thereon by the coil spring 7. The coil spring 7 is disposed within a bushing 8 rig idly connected with the support of the roller member 2 which support may be of any known suitable construction.

The bushing 8 is adapted to slide within a relatively stationary bushing 9 in the embodiment of FIGURE 1 which bushing 9, in turn, is surrounded by an eccentric bushing 10. The eccentric bushing 10 is rotatably sup.- ported within the housing block 11. The rotation of the eccentric bushing 10 takes place over the gear-rimtoothed-rack connection consisting of the gear rim 12 pro.- vided at the upper end of the eccentric bushing 10 and of the toothed rack 13 suitably supported within the housing 11. The linear movements of the toothed rack 13take place thereby essentially in a direction perpendicular to the plane of the drawing of FIGURE 1.

Operation ing engagement with the gear rim 12, a rotation of the eccentric bushing 10 is caused by linear displacement of the toothed rack 13. With a rotation of the eccentric bushing 10, the center axis of the eccentric bore of the bushing 10 moves from the initial position thereof into a position displaced with respect to the axis 14 of the cam shaft. The bushing 9 together with the inner parts thereof and therewith also the tappet itself thereby move toward the right or left, as viewed in FIGURE 1, upon movement of the eccentric bore in bushing 10 caused by rotation thereof.

The displacement components of the tappet 5 perpendicularly to the axis 14 of the cam shaft is indicated in FIGURE 1, for example, by the distance 15.

If the axis 17 of the roller member 2 is disposed exactly vertically above the axis 14 of the cam shaft, then the tappet 5 assumes the highest position thereof, i.e. its upper dead-center position when the highest point or peak 16 of the cam 1 is also disposed exactly vertically above the axis 14.

If now the tappet S is displaced toward the left by an amount or dimensions 15 (FIGURE 1) by rotation of the eccentric bushing 10, then the upper dead-center position thereof, if the direction of rotation of the cam 1 is assumed to be in the direction of arrow 3, is advanced. Of course, the time period of advance is dependent on the rotation of the eccentric bushing 10. By thus advancing the top dead-center position of the tappet 5, an earlier injection of the fuel is achieved.

In the embodiment according to FIGURE 2, the same conditions exist with respect to the drive elements for the tappet 5 as exist in connection with the embodiment of FIGURE 1. As in the embodiment of FIGURE 1, the roller member 2 of the embodiment of FIGURE 2 also runs along the surface 4 of the cam 1. In the normal or center position, the tappet 5 is in the upper deadcenter position thereof when the highest point or peak 16 of the cam 1 is disposed vertically above the axis 14 of the cam shaft.

A displacement of the roller member 2 from the normal or center position thereof is obtained, in FIGURE 2 by pivotal movement of the entire tappet guide means about the point 18. Point 18 thereby represents the effective pivot axis, indicated in FIGURE 2 by a small circle. The entirety of the tappet guide means consists of an arm 20 and of a bushing 19 which is provided on the inside thereof with the cylindrically shaped sliding surface for the guide bushing 8 of the tappet 5. The bushing 19 is inserted into the housing 11 with plentiful play.

The totality of parts constituting the tappet and tappet guide means is pivoted about the pivot axis 18 by an cecentric 21 corresponding to the

double arrows

22 and 23. The eccentric 21 itself is provided with a lever 24 which is adapted to be moved corresponding to the double arrow 25 and therewith leads by adjustment thereof to the rotation of the

parts

19 and 20 which are integral with each other. In order to assure continuous abutment of the arm 20 against the eccentric 21, the arm 20 is springloaded on the side thereof opposite the side of eccentric 21 by a spring 26.

The displacements of the axis 17 of the roller member 2 corresponding to the double arrow 23 lead to an advancing or retarding of the time point of the injection, for the reasons already mentioned and explained in connection with the embodiment of FIGURE 1 in which the tappet 5 assumes the upper dead-center position thereof and therewith eifects the injection of the fuel.

The pivotal movements of the axis 17 of the roller member 2 corresponding to the double arrow 23, therefore, have the same control effects as the essentially horizontal displacements of the tappet guide means according to the embodiment of FIGURE 1, the magnitude of which was indicated in FIGURE 1, for example, by the dimension 15.

While we have shown and described two embodiments in accordance with the present invention, it is under stood 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, the possibility of moving the tappet guide means which constitutes the principal basic concept of the present invention may also be applied to any other suitable manner of construction different from that shown in connection with the embodiments of FIGURES 1 and 2. For example, toothed racks, worm gear drives and the like may be provided which move the tappet guide means or the tappet itself into different positions with respect to the cam shaft axis within a predetermined range. The displacement of the guide means for the tappet or of the tappet itself thereby takes place advantageously, preferably in a direction perpendicular to the cam shaft axis.

Thus, it is quite obvious that the present invention is not limited to the two embodiments illustrated herein but is susceptible of many changes and modifications within the spirit and scope of the present invention and we, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

We claim:

1. An adjusting mechanism for adjusting the time of the injection point for injection pumps comprising tappet means, cam means for driving said tappet means, and guide means for adjustably guiding said tappet means within said mechanism to move said tappet means in a plane extending essentially perpendicularly to the axis of said cam means, said guide means being rotatable about a pivot axis.

2. An adjusting mechanism according to claim 1, wherein said pivot axis is parallel to said cam axis.

3. An adjusting mechanism according to claim 1, wherein said pivot axis is disposed at an upper end portion of said tappet means.

4. An adjusting mechanism according to claim 3, further comprising arm means for effecting pivotal movement of said tappet guide means, and eccentric means for actuating said arm means.

5. An adjusting mechanism according to claim 3, wherein said guide means includes an arm portion and a guide bushing rigidly connected with said arm portion, and an eccentric lever for actuating said arm portion upon rotation thereof.

6. An adjusting mechanism for adjusting the time of the injection point for injection pumps used with internal combustion engines, comprising a relatively fixed part, guide means including a bushing portion inserted within said fixed part with play and an arm portion rigidly connected with said bushing portion, tappet means including a guide bushing slidingly received within said bushing portion, cam means, a roller member adapted to ride along said cam means, support means rigidly connected with said guide bushing for supportingly connecting said roller member with said tappet means, said guide means being rotatable about a pivot axis disposed above said bushing portion, and an eccentric lever in operative engagement with said arm portion for pivoting said arm portion and therewith said tappet means about said pivot axis and thereby effect an advancement or retardation of the point of injection upon rotation of said eccentric lever.

7. An adjusting mechanism according to claim 6, further comprising spring means for spring-loading said arm portion into engagement with said eccentric lever.

8. An adjusting mechanism according to claim 7, wherein said tappet means has a longitudinal axis, and wherein said pivot axis is located along the upper end of said tappet means essentially transversely of the longitudinal axis thereof.

9. An adjusting mechanism for adjusting the time of the injection point for injection pumps comprising tappet means, cam means for driving said tappet means, and guide means for adjustably guiding said tappet means within said mechanism to move said tappet means essentially perpendicularly to the axis of said cam means, said guide means including a cylindrical member disposed radially outward of said tappet means, and means for imparting rotation to said cylindrical member in selective opposite directions, said cylindrical member being pivotal about a pivot axis, said pivot axis being parallel to said cam axis.

10. An adjusting mechanism for adjusting the time of the injection point for injection pumps comprising tappet means, cam means for driving said tappet means, and 10 2,179,354

guide means for adjustably guiding said tappet means within said mechanism to move said tappet means in a plane extending essentially perpendicularly to the axis of said cam means, said cylindrical member being pivotal about a pivot axis, said pivot axis being disposed at an 5 upper end portion of said tappet means.

References Cited in the file of this patent UNITED STATES PATENTS 2,053,027 Franks Sept. 1, 1936 Scott Nov. 7, 1939 3,040,723 Scherenberg et a1 June 26, 1962