Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2000-02-04
2001-03-06
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C417S499000
Reexamination Certificate
active
06196198
ABSTRACT:
The invention relates to a regulating device for controlling the delivery flow in a motor-fuel injection pump, the regulating device being provided with a pump cylinder, a pump piston with inclined control edge and an adjusting sleeve, which embraces a piston foot of the pump piston while allowing free motion in axial direction, the piston foot being guided exactly in rotational direction by the adjusting sleeve.
Such regulating devices are known from the prior art for controlling the delivery flow of a motor-fuel injection pump, especially for diesel engines. They usually operate on the overflow principle with control by an inclined edge, thus permitting regulation of the delivery flow by turning the pump piston. The pump piston has a longitudinal groove, via which the pressure space above the piston is always in communication with the space disposed underneath an inclined edge (control edge). The useful stroke of the pump piston can therefore be changed by turning it. This is achieved by a regulating rod, which engages on the adjusting sleeve via a toothed ring. In this way the adjusting sleeve is firmly joined to the pump piston without influencing the stroke motion thereof. Control of the regulating-rod motion is then exerted either mechanically or electronically.
A practical example according to the prior art is shown in
FIG. 9
, wherein regulating rod
80
is provided with a toothing which engages in the outer toothing of adjusting sleeve
81
. Under these conditions, adjusting sleeve
81
must permit axial motion of pump piston
82
in pump cylinder
83
, but can turn this piston in circumferential direction.
The known regulating devices of the type explained in the foregoing require a complex manufacturing process and, during operation, tend to stick because the guide surfaces between adjusting sleeve and piston foot are in intimate contact; their frictional wear is correspondingly severe.
A regulating device with comparatively less tendency to sticking is described in Japanese Patent Application JP A 60132064. Therein, however, the inclination of the pump piston is variable because of relatively large play, since the inside diameter of the adjusting sleeve greatly exceeds the major diameter of the piston foot; only in the region of bottom dead center is the play in the said direction greatly reduced by a short crimp. In all other positions, on the other hand, considerable wear can be expected because of the large permissible inclination of the pump piston.
In contrast, the object of the present invention is to provide, for controlling the delivery flow of a motor-fuel injection pump, a regulating device of the type mentioned in the introduction which permits trouble-free and low-wear operation and can be manufactured inexpensively.
This object is achieved according to the body of claim
1
.
By the fact that the piston foot is exactly guided by the adjusting sleeve in rotational direction regardless of stroke position, and by the fact that the adjusting sleeve embraces with its pump-side end a cylindrical portion of the pump cylinder while allowing axial displacement and rotational motion, it is guaranteed that the regulating device can be actuated without sticking.
In a further particularly advantageous embodiment of the invention, a regulating turning-lever plate is joined to the tubular profile at its end facing the pump cylinder, which plate intimately embraces the pump cylinder in circumferential direction in the manner of a partial circular arc.
According to the invention, it is provided in a regulating device of the present class that the adjusting sleeve has an elongated thin-walled tubular profile, preferably of deep-drawn sheet metal, a regulating turning-lever plate joined to the tubular profile, and a regulating turning lever on the regulating turning-lever plate. This permits inexpensive manufacture and low-wear and trouble-free operation.
An advantageous further design of the present invention provides that the regulating turning-lever plate is joined to the tubular profile at its end facing the pump cylinder. This can be achieved, for example, in that the tubular profile passes through the regulating turning-lever plate at two oppositely disposed circular portions and is braced against the regulating turning-lever plate at two further oppositely disposed circular portions.
It is also advantageous for the regulating turning-lever plate to embrace the pump cylinder in such a way that it is rotatable in circumferential direction relative to the pump cylinder. Hereby the adjusting sleeve is guided by the pump cylinder. For example, the two sides of the regulating turning-lever plate through which the tubular profile does not pass can be in close-fitting contact with the pump cylinder.
An advantageous embodiment of the present invention provides that line contact exists between piston foot and adjusting sleeve. This means that, by appropriate structural design of the tubular profile and of the piston foot, only contact points disposed along a line and not surfaces bearing over an area are formed. Only the piston foot is in contact with the adjusting sleeve. Thus maximum axial freedom of motion of the pump piston is assured while at the same time effective rotational capability thereof is achieved. Such features therefore work against tilting and wear.
Another advantageous embodiment provides that preferably only point contacts are formed between piston foot and adjusting sleeve. Hereby the friction between piston foot and adjusting sleeve is minimized and frictional wear is greatly reduced. In addition, the danger of sticking of the piston foot in the adjusting sleeve is minimized.
An advantageous further design of the invention provides that the adjusting sleeve has a tubular profile with crimps parallel to the longitudinal axis. This permits simple geometry of the piston foot and line contact thereof with the adjusting sleeve. In addition, the crimps permit relatively simple manufacture of the tubular profile and impart additional stiffness thereto. As an alternative to this embodiment, the adjusting sleeve can have a smooth tubular profile. This means that the adjusting sleeve, which has a cruciform or cloverleaf-shaped cross section, is provided, in contrast to the crimped tubular profile, with smooth walls, and the point or line contact is established by the shape of the piston foot.
Finally, an advantageous further design of the invention provides that the piston foot has convex structures protruding at the contact points. These convex structures resemble hemispheres attached to the piston foot. Such a piston-foot geometry can be manufactured by, for example, an erosion process. Such a structure in combination with a smooth tubular profile achieves point contact and thus minimum wear and reliable operation.
Another further design of the present invention provides that the tubular profile and regulating turning-lever plate are welded to one another. In this case, welding methods with low thermal distortion are particularly suitable. A small number of weld spots is sufficient for this purpose.
Yet another design of the present invention provides that the tubular profile and the regulating turning-lever plate are riveted to one another. This is advantageous for small production runs in particular and permits a nonpositive joint without thermal distortion.
Finally, it can be useful in a further embodiment of the invention for the tubular profile to have an antifriction coating. This can be, for example, a friction-reducing metal or plastic coating (such as Teflon), which is applied on the sheet metal of the tubular profile.
REFERENCES:
patent: 3624823 (1971-11-01), Staudt
patent: 4430977 (1984-02-01), Shimada
patent: 4625700 (1986-12-01), Elsbett et al.
patent: 4630586 (1986-12-01), Guntert et al.
patent: 4737086 (1988-04-01), Yamaguchi et al.
patent: 4754737 (1988-07-01), Ishida et al.
patent: 4793316 (1988-12-01), Seiler et al.
patent: 4840161 (1989-06-01), Eckell et al.
patent: 5097812 (1992-03-01), Augustin
patent: 35 44 051 (1987-06-01), None
paten
Helfgott & Karas P.C.
Motorefabrik Hatz GmbH & Co. KG
Moulis Thomas N.
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