Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1994-07-05
1995-09-19
Yuen, Henry C.
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9031, 464 2, 74568R, F01L 134, F16D 310, G05D 1340
Patent
active
054508258
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a method for activating a device for the relative rotation of a shaft and on a device for the relative rotation of the camshaft of an internal combustion engine relative to the drive wheel of the camshaft rotatably arranged on the same. In known devices and methods of this type for the activation, a piston/cylinder device is acted upon by means of a control valve, and the piston displaces a coupling element which is supported in a recess of the camshaft. On the coupling element, which is in engagement with the camshaft, there are straight and helical teeth which, when the setting piston is displaced, rotate the camshaft relative to the drive wheel. A hydrostatic pump driven by the camshaft supplies the pressure medium necessary for the adjustment of the setting piston. The setting piston is subjected to pressure at both ends, one end being continually subjected to the pressure generated by the pump. The pressure on the other end of the piston is varied, as a function of certain control parameters, by the control valve by pressure reduction or by permitting pressure medium to flow away (de-activation). A method of this type and a device of this type are very complex and also, therefore, complicated and, more particularly, require a high expenditure of energy.
SUMMARY OF THE INVENTION
The method according to the invention for activating a device for the relative rotation of a shaft in accordance with which the control valve connects the pump, as a function of its working phase (suction phase/pressure phase), with respectively one of the pressure spaces of the setting element, has, in contrast, the advantage that a very rapid and energy-favourable mode of operation is possible. A device for the relative rotation of the shaft of an internal combustion engine, characterized in that the setting element is located within the drive wheel of the shaft and is configured as a rotary piston actuator whose hub is arranged so that it is fixed on and rotates with the central housing located in the middle of the control valve, and in the rotor of the hydraulic pump is arranged on the same axis as the rotary piston actuator and is driven by the camshaft, can be operated in a particularly advantageous manner with a method of this type.
The device according to the invention for the relative rotation of the camshaft of an internal combustion engine, has the advantage that it is configured in a simple manner and is also particularly compact in construction. It is, more particularly, characterized by a very low energy requirement. The oil loss is limited to leakage losses because the oil quantities to be displaced from the setting gear are re-induced by the pump. In a preferred embodiment of the invention, the adjusting element is hydraulically locked in the rest position by means of the control valve; there is no forced control deviation. The energy consumption in this embodiment is particularly low because energy consumption only takes place during the adjustment.
In another preferred embodiment, the complete pump revolution is used in an advantageous manner for the delivery and adjustment, independent of the pump working space (individual pump) which is currently delivering. The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings show a longitudinal section through a camshaft adjusting device in FIG. 1, a section along II--II of FIG. 1 in FIG. 2, a section along III--III of FIG. 1 in FIG. 3 and working diagrams of the pumps and associated valve activation systems used in the device in FIGS. 4 to 7 (a to e in each case).
DESCRIPTION OF THE PREFERRED EXAMPLES
In the drawin
REFERENCES:
patent: 5189999 (1993-03-01), Thoma
patent: 5247914 (1993-09-01), Imai et al.
patent: 5305718 (1994-04-01), Muller
patent: 5311846 (1994-05-01), Muller
patent: 5329890 (1994-07-01), Muller
Geyer Gerhard
Mendle Johann
Lo Weilun
Robert & Bosch GmbH
Striker Michael J.
Yuen Henry C.
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