Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
1999-12-21
2001-02-27
Lo, Wellun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090310, C074S56800M
Reexamination Certificate
active
06192843
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a device for adjustment of the angular position of a shaft, preferably a camshaft of an internal combustion engine, relative to a driving wheel, comprising an adjusting device for adjustment of the angular position starting from a base position and comprising an arresting device for arresting the angular position in the base position, said adjusting device including at least one first component capable of being connected non-rotatably to the shaft and at least one second component capable of being connected non-rotatably to the driving wheel, said components being angularly adjustable relative to one another along an interface, the arresting device including at least two interengaging parts one of which is located in the first component and the second in the second component.
BACKGROUND OF THE INVENTION AND PRIOR ART
Angular adjustment devices are often used in internal combustion engines in order to shift the position of the camshaft relative to the crankshaft by a predetermined angle. The camshafts operate the valves according to the profile of their cams, the resulting fixed valve control times merely representing a compromise, above all with respect to the rated power, torque, fuel consumption and exhaust gas emission requirements of the internal combustion engine. The phase shift of the control times associated with the adjustment in the angular adjustment serves the purpose of optimisation.
The angular adjustment is mostly effected hydraulically, and a fall in the hydraulic pressure below a lower limiting value may lead to undesired positions of the camshaft relative to the crankshaft, which are accompanied by high loads on the components. In order to avoid undesired positions of the camshaft in case of inadequate hydraulic supply it is known to provide a device which, if the hydraulic pressure is too low, brings the camshaft into a base position and arrests it in this position until the oil pressure has reached an adequate value for stable control of the system, for example after starting the internal combustion engine. Otherwise, it can in fact happen that until the predetermined oil pressure has been reached an uncontrolled angular adjustment occurs which in case of a possibly necessary repetition of the starting of the internal combustion engine leads to starting problems.
German Offenlegungsschrift 39 37 644 discloses a device for hydraulic angular adjustment in which an impeller wheel attached coaxially on the shaft side is received in a cellular wheel secured on the driving wheel side. A device for arresting the shaft in its base position includes a slidably movable arresting sleeve located coaxially in the cellular wheel or impeller wheel and held non-rotatably by means of a locking profile, and blocking grooves located in the respective counterpart wheel and aligned with the locking profile, the arresting sleeve being moved out of the arresting position by a servomotor. A disadvantage of this device is that it requires a relatively large amount of space in the axial direction of the shaft and is expensive to make both mechanically and in respect of control technology.
OBJECT OF THE INVENTION
In contrast to this, the object of the invention is to improve a device of the kind referred to so that it needs less space and is of simpler design.
SUMMARY OF THE INVENTION
In accordance with the invention, to achieve this object the at least two parts of the arresting device are located between the components in an interface located eccentrically to the shaft and having a longitudinal extent running circumferentially of the shaft, the one part being formed as an arresting pin element movable at an angle to the interface and the other part as an arresting recess into which a portion of the arresting pin element can engage when in the base position, the arresting element being mechanically preloaded in the engagement direction and being movable counter to the engagement direction by the pressure of a control fluid.
Locating the arresting device eccentrically of the shaft makes it possible to take up the arresting forces in the cross sectional area of the arresting pin element by means of a shearing load. The load can thereby be carried in a smaller region than in the case of projections located on the circumferential surface. In addition to this, the arresting pin element no longer has to be a hollow section surrounding the shaft, but can be designed as a full section, thus enabling the space required to be further reduced. Since the arresting device is offset radially outwards and accordingly can be located beside the shaft, both the space required for axial prolongation of the shaft and also (depending on the radial distance selected) the dimensions are reduced, since the forces to be taken up become less as the distance becomes greater, i.e. as the lever arm becomes longer. In addition the arresting device, absent the need to provide a cavity, merely includes an arresting pin element and an arresting recess, so that the arresting device does not require any difficult working or surface shaping and the manufacturing costs can be considerably reduced. Since the arresting pin is arranged and movable at an angle to the interface, and the angle does not need to be 90° but can have an arbitrary value, the site and position of the arresting device can be adapted as desired to the constructional specifications or requirements. A further saving of space and simplification of the construction is achieved in that the arresting pin element is mechanically preloaded into the engaging position and is movable in the other direction by means of a control fluid. Separate motorised driving devices are not necessary. Another consequence of this is increased operational reliability in the case of a device in accordance with the invention, since any sources of error, for example failure of a driving motor for actuation of the arresting device, are excluded right from the beginning.
Preferably the two components exhibit regions of flange-like form between which there extends an interface running substantially radially in which the arresting device is located. This makes for further simplification, since only substantially perpendicular surfaces have to be produced.
In a preferred further embodiment of the invention the arresting pin element is movable in the longitudinal direction of the shaft. This measure also greatly limits the space requirements in the radial direction.
Preferably several arresting pin elements and associated arresting recesses are arranged round the circumference of the shaft. This measure gives a conforming distribution of the forces occurring, and particularly in the case of uniform distribution of the arresting pin elements and recesses a uniform distribution of the forces is also achieved.
In a further advantageous development of the invention the two components exhibit assembly recesses opening into the interface and coinciding when in the base position. In the case of a substantially radially extending interface between the two components it is particularly preferred that these recesses extend substantially in the longitudinal direction of the shaft. The assembly recesses serve to align or “zero” the parts of the whole system with all its tolerances both for the initial assembly and also in subsequent servicing. During the assembly and/or the servicing an assembly pin element can be pushed into the assembly recesses. The components can thus be simply twisted relative to one another until the desired base position is reached in which the arresting pin element lies opposite the arresting recess. In this position the whole device can be fixed in position, for example by means of a necked-down bolt by means of which the components are connected to the end face of a camshaft, whereby the tolerances in the device are compensated. This is particularly advantageous in the case of mass production, with its inevitable tolerances.
Providing a plurality of assembly recesses arranged around the circumference of the shaft again ma
Laufenberg Dietmar
Steinberg Rainer
Ford Global Technologies Inc.
Lo Wellun
McKenzie Frank G.
LandOfFree
Angular adjustment device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Angular adjustment device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Angular adjustment device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2562382