Pumps – With condition responsive pumped fluid control – Plural pump units with individual or relative control
Reexamination Certificate
1999-02-25
2001-03-27
Freay, Charles G. (Department: 3746)
Pumps
With condition responsive pumped fluid control
Plural pump units with individual or relative control
C417S427000
Reexamination Certificate
active
06206651
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine with internal combustion with at least one pair of toothed wheels which are in mutual engagement, at least one intake port and at least one outlet port.
DESCRIPTION OF THE PRIOR ART
Oil pumps for internal combustion engines which are intended for motor vehicles in particular are usually arranged as gear pumps. They consist of a pair of toothed wheels which are in mutual engagement, with the conveyance of oil being caused by the displacement effect of the teeth. The conveying effect of such gear pumps substantially depends linearly on the speed of rotation with which these gear pumps are driven. As the drive is generally performed directly by way of the internal combustion engine, the pump output is therefore substantially proportional to the rotational speed of the internal combustion engine. The oil quantity required for the operation of the internal combustion engine, however, is not linearly dependent on the rotational speed. This means that in a number of speed ranges, namely particularly at low engine speeds, there is a danger of a lack of supply with oil, whereas in other engine speed ranges a relatively large quantity needs to be removed by way of pressure control valves.
SUMMARY OF THE INVENTION
It is the object of the present invention to improve an oil pump of the kind mentioned above in such a way that these disadvantages are avoided. It is the object of the present invention in particular to reduce the energy requirements for the drive of an oil pump in order to increase the total efficiency of internal combustion engines. These objects are achieved in accordance with the invention with at least two pairs of toothed wheels, a first common shaft on which a first toothed wheel of each pair of toothed wheels is arranged and means are provided in order to charge with oil the individual pairs of toothed wheels depending on the required quantity of conveyed oil.
In the case of the solution in accordance with the invention it is possible to adjust the oil pump output in certain stages to the actual demand. Although the dependence of the conveying quantity on the rotational speed is principally still retained in the solution in accordance with the invention, the factor of proportionality can be changed.
The solution in accordance with the invention is arranged in such a way that in the case of a relatively low demand for oil only one pair of toothed wheels will assume the actual conveyance. In the case of maximum oil demand all pairs of toothed wheels are used in parallel with one another for the conveyance.
In order to prevent no-load losses to the highest possible extent, it is advantageous that each pair of toothed wheels is assigned an own intake port and an own outlet port and that a valve is provided in order to optionally connect at least one intake port with the associated outlet port. The idly running pair(s) of toothed wheels is/are operated in circulation and substantially pressureless, so that cooling and lubrication are ensured and that with the exception of frictional losses no driving torque is required for the movement of the toothed wheels.
In a particularly simple embodiment of the present invention it is provided that a control valve is provided in order to optionally supply the individual pairs of toothed wheels with oil and that the oil pressure in the outlet line is used as a control pressure for said control valve. As an alternative it may also be provided that an electronic control apparatus is provided in order to charge with oil the individual pairs of toothed wheels. The oil pump in accordance with the invention can be controlled in an intelligent manner by the engine management. In this way it is also possible to cover any additionally required oil demand which can result from an apparatus for changing the setting angle of a camshaft for example.
There is an increase in the number of possibilities for adjustment in that the individual pairs of toothed wheels have a different width. In an oil pump with two pairs of toothed wheels, for example, this allows achieving three different characteristic performance curves.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be explained in closer detail by reference to the embodiments shown in the figures, wherein:
FIG. 1
schematically shows an embodiment of the present invention;
FIG. 2
shows a sectional view through an oil pump in accordance with the invention; and
FIG. 3
shows a diagram in which the conveyed quantity is entered over the drive speed.
REFERENCES:
patent: 3068795 (1962-12-01), Lauck
patent: 3385217 (1968-05-01), Bles
patent: 4002027 (1977-01-01), Eley et al.
patent: 5094597 (1992-03-01), Takai et al.
Buha Gerald
Klaus Heinz
Dykema Gossett PLLC
Freay Charles G.
TCG Unitech Aktiengesellschaft
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