Hydraulic adjusting arrangement for an injection pump

This invention relates to a hydraulic adjustment arrangement for the control of the injection start for a motor vehicle internal combustion engine, consisting of a primary part on the side of the internal-combustion engine and a secondary part on the side of the injection pump as well as radial pistons operating as a function of the admission of hydraulic oil, said radial pistons operating as a function of the admission of hydraulic oil, said radial pistons being guided in cylinders contained in the secondary part and interacting with levers extending in a circumferential direction and being pivoted on the secondary side, flexible connectors resting on said levers in one portion and fixed to the primary part on another portion, such that a radial movement of the pistons and as corresponding outward swivel movement of the levers and the flexible connectors causes a rotation of the secondary part relative to the primary part. A low-pressure hydraulic system is sufficient for the operation of the hydraulic adjusting device because the movement of the radial pistons is also supported by the centrifugal forces occurring with increasing speed of the internal-combustion engine.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to a timing device, more 
particularly to a timely adjustment device for the control of the fuel 
injection start for a motor vehicle internal-combustion engine. Preferred 
embodiments of the invention relate to an arrangement for controlling the 
fuel injection start, wherein a connection; having one section fixed to 
move with a primary part of the transmission and another section 
positioned to move with a secondary part of the transmission, effects a 
circumferential rotation of the secondary part with respect to the primary 
part. 
Based on U.S. Pat. No. 3,973,540, a hydraulic adjusting device is known 
where the rotating movement between the primary part and the secondary 
part is forced as a function of the admission of pressure medium to the 
piston via diagonally extending slot guiding means. 
Also, a hydraulic adjusting device is known from U.S. Pat. No. 3,685,499 
where the axially acting piston is connected with the primary part by an 
expensive toothing. In this case, the toothing is to permit a rotationally 
stable connection as well as a relative movement in an axial direction 
between the primary part and the piston. For the relative rotational 
movement between the primary and the secondary part, balls are provided as 
transfer members which are guided in diagonally extending guide grooves. 
The invention is based on the objective of creating, in view of the 
embodiment according to U.S. Pat. No. 3,685,499, a hydraulic adjusting 
device where a rotation of the secondary part relative to the primary part 
can take place with little or no hydraulic pressure adjusting angles. 
This objective is achieved by the effective direction of the piston as well 
as the arrangement and development of the transfer members connected with 
this piston. In the particular embodiment shown in FIGS. 1-3, the flexible 
connector, which effects circumferential rotation of the second any part 
with respect to the primary part is comprised of a chain linkage attached 
to the primary part of the transmission by means of a bolt through one 
link and positioned with respect to the secondary part of the transmission 
in such a way that the linkage rests on a lever which is pivotally 
attached to the secondary part. By these arrangements, operation of the 
hydraulic timing adjustment arrangement is achieved at a low pressure, 
such as the engine oil pressure, because the radial movement of the piston 
as well as the swivel movement of the lever is supported by the 
centrifugal forces occurring at an increasing speed of the 
internal-combustion engine. 
Further, objects, features, and advantages of the present invention will 
become more apparent from the following description when taken with the 
accompanying drawing(s) which show, for purposes of illustration only, an 
embodiment constructed in accordance with the invention.

DETAILED DESCRIPTION OF THE DRAWINGS 
As shown in FIG. 1, a hydraulic timing adjustment arrangement 1 in the 
embodiment of a radial-piston timing injection mechanism for the control 
of the fuel injection start for a motor vehicle internal-combustion engine 
is mounted on the camshaft 2 of a conventional injection pump that is not 
shown. The arrangmeent consists of a primary part 3 on the drive side and 
a secondary part 4 on the side of the injection pump. 
As shown in FIGS. 1 and 2, the secondary part 4 is composed of a bearing 
sleeve 6 connected with the injection pump shaft 2 by means of spline 5, 
and a cylinder housing having three cylinders 7a, 7b, 7c evenly 
distributed in a circumferential direction. Crowned radial pistions 8 are 
guided within the cylinders, and move in a direction perpendicular to or 
approximately perpendicular to the axis of the shaft 2. 
A lever 9 extending in circumferential direction is pivotally attached to 
the secondary part by swivel shaft 10 and to a respective radial piston 8. 
In the close area of the swivel shaft 10, a flexible connector 11 
illustrated as a chain piece is rotably fastened to the lever 9. The chain 
links 11a of the flexibile connector 11 complete or partially rest on the 
arched back 9a of the lever 9, depending on the position of the radial 
piston 8. The free driving arm 11b of the flexible connector 11 is fixed 
to the primary part 3 by means at a bearing bolt 12. The primary part 3 is 
equipped with a drive toothing 3a and is pivoted on a part of the bearing 
sleeve 6 that projects from the end. The primary part 3 has projections 13 
at which pull-back springs 14 support themselves. The pull-back springs 14 
are connected with the secondary part 4 and are developed as torsion 
springs. 
The hydraulic timing adjustment arrangement operates as follows. 
The three radial pistons 8 are hydraulically operated by hydraulic oil 
which, via an arrangement 16 of bores, namely a radial bore 16a and an 
axial bore 16b in the injection pump shaft 2, and an oil bore 17 in the 
bearing sleeve 7, is fed to the respective pressure spaces 18 that are 
defined by the radial pistons 8 and the wall surfaces of the cylinders 7a, 
7b and 7c. The radial movement of the radial piston 8 causes a swivel 
movement of the lever 9 which is pivotally attached to the pistons and to 
the secondary part. Additionally, the radial movement of the piston 8 and 
the subsequent movement of the lever 9 due to the hydraulic pressure is 
supported on the centrifugal forces occurring at an increased speed of the 
internal combustion engine. In the process, the flexible connectors 11 are 
forced outward and deformed changing the spacing in the circumferential 
direction of the bearing points on the primary and the secondary side. The 
rotation of the primary part and the secondary part with respect to one 
another causes a rotation of the injection pump shaft 2 which corresponds 
to a change of the injection start. In the case of a pressure relief of 
the piston 8, the torsion springs 14, which act against the force of the 
upward moving radial pistons 8, cause the readjustment of the secondary 
part relative to the primary part back into the starting position. 
The inflow or the outflow of the hydraulic oil to the radial piston is 
controlled via a servo valve that is controlled by an electronic 
regulating system which is connected to the motor oil circulating system 
(not shown). Thus, the actual value of the adjusting angle corresponds to 
the desired value determined by the electronic regulating system according 
to speed, load and temperature.