Fuel injection timing system

Internal-combustion engines – Charge forming device – With fuel pump

Reexamination Certificate

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Details

C464S160000

Reexamination Certificate

active

06240906

ABSTRACT:

TECHNICAL FIELD
The present invention relates to fuel injection systems for internal combustion engines. More particularly, it relates to an improved apparatus for controlling the timing of fuel injection pumps in internal combustion engines.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,630,402, granted May 20, 1997, to Michael J. Devine and Robert L. Kiliz, and assigned to Timing Systems, Inc., of Seattle, Wash., discloses and covers a fuel injection timing system that comprises an input drive member, an output drive member and an intermediate drive member. The output drive member is adapted to be rotatably coupled to a pump shaft of a fuel injection pump, to rotate the fuel injection pump shaft about its axis. The input drive member is adapted to be rotatably coupled to a drive source. The intermediate drive member is axially movable along an axis of the pump shaft between the input and output drive members. An actuator is provided that is movable along an axis that is perpendicular to the pump shaft axis. The actuator is coupled to the intermediate drive member and is adapted to move the intermediate drive member along the pump shaft axis. The intermediate drive member is coupled to the input drive member in a manner where axial movement of the intermediate drive member causes the intermediate drive member to rotate about the pump shaft axis. The intermediate drive member is coupled to the output drive member in a manner where movement of the intermediate drive member along the pump shaft axis causes rotational movement of the output drive member about the pump shaft axis. The actuator moves the intermediate drive member axially along the pump shaft axis to adjust the angular position of the output drive member relative to the input drive member.
The apparatus that is disclosed in U.S. Pat. No. 5,630,402 includes a pair of radially projecting pins on the intermediate drive member. The pins are positioned one hundred eighty degrees (180°) apart on opposite sides of the intermediate drive member. The output drive member includes a pair of helical slots. The helical slots formed in the output drive member are also positioned one hundred eighty degrees (180°) on opposite sides of the output drive member. Each helical slot is adapted to receive one of the pins and to cause is rotation of the output drive member in response to movement of the intermediate drive member axially along the pump shaft axis.
In such apparatus, the input drive member also includes a pair of helical slots, each adapted to receive a pin. The helical slots in the input drive member are curved in a direction opposite to that of the helical slots in the output drive member. As a result, linear movement of the intermediate drive member causes rotation of the intermediate drive member due to the pins engaging the helical slots in the input drive member.
The apparatus disclosed by U.S. Pat. No. 5,630,402 also includes a drive plate that is axially movable and includes a pair of radially projecting trunnions. It further includes a yoke having side members, each having an angled slot. The radially projecting trunnions on the drive plate are received within the angled slots. Movement of the yoke in a direction perpendicular to the pump shaft axis causes the. drive plate to move axially along the pump shaft axis. The drive plate is coupled to the intermediate drive member so that as it moves, it moves the intermediate drive member with it, along the pump shaft axis.
An object of the present invention is to provide new embodiments of the fuel injection timing apparatus that is disclosed in and covered by U.S. Pat. No. 5,630,402.
Another object of the present invention is to provide an improvement in the way in which the input drive member and the output drive member are coupled to the intermediate drive member.
A further object of the present invention is to provide an improved construction of the housing for the fuel injection timing system.
Yet another object of the present invention is to provide improvements in the way the yoke is driven and guided and variations in the way the fuel pump shaft is coupled to the output drive member.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, the intermediate drive member is a sleeve. It is provided with internal and external splines that are distributed circumferentially about the intermediate drive sleeve. A tubular inner end portion of the input drive member is provided with external splines that are distributed circumferentially about said end portion and mesh with the internal splines on the intermediate drive sleeve. A tubular inner end portion of the rotary output drive member is provided with internal splines that are distributed circumferentially about said inner end portion and mesh with the external splines on the intermediate drive sleeve. All of the splines extend along helical paths so that movement of the intermediate drive sleeve axially will rotate the intermediate drive sleeve in position relative to both the rotary input drive member and the rotary output drive member and will rotate the rotary output drive member in position relative to the rotary input drive member.
According to another aspect of the invention, a ball nut is connected to the top of the yoke and it includes a helical, internal groove. A ball screw extends into the ball nut and includes a helical, external groove. Ball bearings are received partially within the internal groove and partially within the external groove, for coupling the ball screw to the ball nut. A stepper motor provides a reversible drive for the ball screw. Stepper motor rotation of the ball screw in one direction will cause the ball screw to screw itself in the ball nut and exert a pulling force on the yoke. Stepper motor rotation in the opposite direction will cause it to screw itself out from the ball nut and exert a pushing force on the yoke.
A further aspect of the invention is to mount the stepper motor housing on one side of a housing for the ball screw, the ball nut and the yoke. The stepper motor is mounted with its output shaft directed upwardly and parallel to and spaced from the ball screw. A drive transmission connects the stepper motor output shaft to the ball screw. In preferred form, the drive transmission is a pulley and belt transmission. It includes a first pulley on the output shaft of the stepper motor, a second pulley on the ball screw and a belt drive that interconnects the two pulleys.
Yet another aspect of the invention is to provide a housing having a top wall, a bottom wall and a pair of laterally spaced apart side walls interconnecting the top and bottom walls. The top, bottom and side walls are of a one-piece construction, providing the housing with a tubular shape and an inner cavity. The yoke is snugly received within the cavity such that the sidewalls of the housing function to guide the yoke for up and down movement within the cavity along a substantially straight line path. The top of the yoke may be spaced from the top of the housing to provide a space over the yoke in which the ball nut is received. The remaining two sides of the housing may be in the form of removable plates that are connected to the ends of the tubular main body of the housing.
A still another aspect of the invention is to provide a construction whereby the drive source is connected to the rotary input drive member on one side of the housing and the pump shaft of the fuel injection pump projects outwardly away from the second side of the housing. Or, the pump shaft of the fuel injection pump extends from its connection to the rotary output drive member back, concentrically through the rotary input drive member, and leaves the housing from the side where the drive source is connected to the rotary input drive member. The invention further includes various concepts and combinations of concepts which are general in nature and are inherently disclosed by the specific structures that are disclosed.


REFERENCES:
patent: 4305367 (1981-12-01), Imasato
patent: 5426992 (1995-06-01), Morii et al.
patent

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