Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2001-03-23
2003-09-02
Vo, Hieu T. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S102000, C701S103000
Reexamination Certificate
active
06615128
ABSTRACT:
The invention relates to a method for electronically minimizing to eliminating rated output deviations (trimming) of a fluid injection apparatus, in particular of a fuel injection apparatus, primarily a fuel injection apparatus having a plurality of injection pumps for an internal combustion engine.
For operation of a fuel injection apparatus for an internal combustion engine, it is known for a control signal to be produced which causes an injection pump to inject into an engine cylinder, at a specific time, within a specific time period and as accurately as possible, that amount of fuel which the engine needs in order to produce a demanded, predetermined output power.
The control signal is calculated and produced in an electronic control module and is passed on to the electronic and/or electrical devices in the injection apparatus or in the injection pump where it initiates and brings about the spraying of, for example, fuel corresponding to the control signal.
The production of the control signal is complex and generally includes a particular control strategy. A large number of influencing variables are taken into account which are, for example, related to engine operation, related to the engine environment, related to the type of fuel, and/or related to the fuel state. Data for these influencing variables are generally determined by means of sensors, and are supplied to the control module. For example, the engine speed, the crankshaft position, the engine coolant temperature, the engine exhaust gas pressure, the throttle valve position, the external temperature, the air pressure or the like are detected at a specific time, are supplied to the control module, and are processed or calculated in the form of data in the control module. The calculation produces a factor by which a control signal is multiplied, said control signal being stored in the control module for the engine, corresponding to the rated output of the engine, and being proportional to the quantity.
It is also known that, for example, the design, operating state and operating conditions of the injection pumps have a considerable influence on the time and the duration of the spraying process, with, in particular, even injection pumps of an identical type producing different performance and having a different injection behaviour.
Known solutions for this problem are described in DE 195 20 037 A1 which indicates, as a further new solution, the possibility of defining the spraying characteristic of each injection pump individually by measuring the spraying behavior in a large number of operating conditions and operating states, and adapting the control signal on the basis of the measured data.
To define this idea more specifically, the individual injection pumps are subdivided into specific trimming categories with similar discrepancies and a trimming factor for the control signal is defined for each category.
However, it has been found that categorized trimming factors defined in such a way do not sufficiently reduce discrepancies tom the rated output caused by the injection pump.
When designing injection pumps, the aims include, for example, selection of the size and nature of the components and the physical form in such a way that the injection pump has a linear spraying behavior for different spraying rates and spraying times which correspond to the various rated outputs of an engine, so that the respective control signal matching factor can easily be determined. Small required fuel quantities are sprayed for a correspondingly shorter time period, and larger or large amounts are sprayed for a correspondingly longer or long time duration, and the spraying amounts/spray duration ratio should correspond to a straight line on a graph.
This aim to linearize the flow characteristic generally requires debating of the components and/or use of relatively expensive functional parts. Furthermore, the derated type requires considerably more electrical operating power.
The object of the invention is to provide a method for electronic trimming of an injection apparatus which allows more accurate matching of the control signal, based on the injection pump, to the sprayed rated output initiated by the control signal, without any complex design measures relating to the injection pump.
This object is achieved by the features of claim 1. Advantageous developments of the invention are described in the dependant claims.
The essential feature is the selection of the injection pump type. An electromagnetically operated injection pump is used, which operates on the energy storage principle and is described, for example, in WO 92/14925 and WO 93/18297.
By virtue of the system, such injection pumps operate fundamentally non-linearly, for which reason their selection is not directly obvious. Although it is not impossible to ensure a linear spray characteristic by design measures, the disadvantageous measures described above would, however, be required to a particularly pronounced extent in comparison to other injection pump types.
The injection pumps used according to the invention, which are also referred to as energy storage injection pumps in the following text, can be physically set up in such a way that their injection characteristic follows an at least third-order curve as accurately as possible. The spraying characteristic of most known energy storage injection pumps approximately follows per se a third or higher order curve by virtue of the system and the design, so that these pumps do not require any physical change. In cases in which a physical change should be carried out, it is generally sufficient, for example, to lengthen or to shorten the acceleration path of the armature of the pump for storage of kinetic energy, and/or to adapt the saturation behaviour of the electromagnet of the electromagnetic drive in the injection pump. These measures are so simple and involve an effort which is so minor that they are virtually insignificant. These measures also assist the capability to use the full performance potential of the pumps and thus their efficiency both with regard to the feed performance and with regard to the production cost for the respective application.
For the purposes of the method according to the invention, the spraying characteristic of each individual fabricated injection pump is defined in normal conditions (for example at 20° C. and normal atmospheric pressure), with a sufficient number of measured values being determined and processed for the flow curve or feed characteristic, for example in the form of a signal duration/spraying quantity graph. The measured values are used to calculate the finction which corresponds to the third or higher order curve which can be established from the measured values. The function for the third-order curve which, as is known, is in general form given by: Y=A+B
1
X+B
2
X
2
+B
3
X
3
, includes the parameters A, B
1
, B
2
, B
3
with which the individual third-order curve for the injection pump covered individually by the parameters is uniquely defined. In this case, Y is the control signal duration to be determined and X is the quantity of fluid to be sprayed out.
The four parameters are stored electronically and, if required, are linked, for example, to a serial number for the injection pump, are electronically controlled and represent the exact mathematical description of any point on the feed characteristic of this individual injection pump. The electronic control module of the electronic control system uses these parameters where necessary and calculates the switched-on duration signal required for this individual pump to achieve the respectively required injection amount exactly.
The four parameters are expediently marked in a manner known per se on or with the injection pump such that they can be recorded, and accompany the injection pump until it is used, and during its use.
The measurement of the feed profile for the injection pump is expediently restricted to a limited number of individual measurements, for time reasons. However, each individual
Bombardier Motor Corporation of America
Vo Hieu T.
Ziolkowski Patent Solutions Group LLC
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