Method for regulating a fuel delivery system

Abstract

A method for regulating a fuel delivery system without a pressure sensor. The fuel delivery system has a fuel delivery pump, an electric motor, and an evaluation unit. The fuel delivery pump is driven by the electric motor, which is actuated using control variables such that a prespecifiable fuel delivery is achieved. At least two different submethods are executed for ascertaining control variables, which are ascertained in the respective submethod and are supplied to an evaluation unit. The control variables are evaluated regarding their plausibility in the evaluation unit and the electric motor is actuated based on the ascertained control variables from only one or a plurality of submethods.

Claims

1. A method for regulating a fuel delivery system without a pressure sensor, wherein the fuel delivery system has a fuel delivery pump, an electric motor that drives the fuel delivery pump, and an evaluation unit, wherein the electric motor is actuated using control variables such that a prespecifiable fuel delivery is achieved, comprising: executing at least two different submethods, each using different values, to ascertain respective control variables to control the fuel delivery pump; supplying the control variables which are ascertained to an evaluation unit; evaluating the control variables regarding their plausibility in the evaluation unit; and actuating the electric motor based at least in part on the ascertained control variables from only one of the at least two different submethods.

2. The method as claimed in claim 1, wherein the submethods are executed at least one of in parallel and in series.

3. The method as claimed in claim 1, further comprising: evaluating the plausibility of the control variables with aid of external state variables; determining a current operating state based at least in part on the external state variables; and deriving limit values for the control variables from the current operating state that is currently established.

4. The method as claimed in claim 1, further comprising: starting an emergency program in event of an implausibility of values of the control variables established in the evaluation unit.

5. The method as claimed in claim 1, further comprising: defining an operating mode for the fuel delivery system by the evaluation unit; wherein control variables, which have been ascertained based on in each case only one submethod or which control variables have been ascertained based on at least two submethods, are used in each operating mode.

6. The method as claimed in claim 1, wherein a selection regarding the submethod to be used is made in the evaluation unit based at least in part on external state variables.

7. The method as claimed in claim 1, further comprising: activating a calibration unit by the evaluation unit, wherein the calibration unit is associated with one of the submethods and is configured to calibrate the respective submethod.

8. The method as claimed in claim 1, wherein the submethods use external state variables as input variables and ascertain output variables therefrom, wherein the output variables of one submethod can be used as input variables of another submethod.

9. The method as claimed in one claim 1, wherein the method is repeatedly applied to ensure continuous regulation of the fuel delivery by the fuel delivery system.

10. The method as claimed in claim 1, wherein the at least two different submethods each influence different values.

11. The method as claimed in claim 1, wherein the at least two different submethods ascertain respective control variables with different levels of accuracy.

12. An apparatus configured to regulating a fuel delivery system without a pressure sensor, comprising: at least one evaluation unit configured to: receive respective control variables which are ascertained from at least two different submethods, each submethod using different values, to ascertain respective control variables to control the fuel delivery pump; and evaluate the control variables regarding their plausibility; a fuel delivery pump; an electric motor that drives the fuel delivery pump, wherein the electric motor is actuated using control variables such that a prespecifiable fuel delivery is achieved, the control variables ascertained from only one submethod; at least one calibration unit; and at least one data memory.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in greater detail below using exemplary embodiments with reference to the drawings, in which:

(2) FIG. 1 is a flowchart that illustrates the method according to one aspect of the invention;

(3) FIG. 2 is an exemplary illustration for coupling two submethods to one another; and

(4) FIG. 3 is an exemplary illustration of a system for executing the method according to one aspect of the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

(5) FIG. 1 is a flowchart 1 that illustrates the method according to one aspect of the invention in a schematic drawing. The blocks 2 and 3 respectively symbolize one of the submethods applied during the method. Control variables are ascertained from the submethods 2 and 3 and passed on to an evaluation unit. This is illustrated by the block 4. In the evaluation unit, the control variables are checked regarding their plausibility and possibly processed further. This is illustrated by the block 5. Finally, control variables that are processed and possibly weighted by the evaluation unit are passed on to the electric motor 6. The electric motor 6 is actuated by the control variables such that prespecified fuel delivery by the fuel delivery pump is achieved. The method illustrated in FIG. 1 can be repeated in a control loop to ensure continuous adjustment of the work of the electric motor 6 and to provide fuel delivery in as optimum a manner as possible.

(6) FIG. 2 shows, in the block diagram 10, an example of how submethods can be combined with one another. A volume-regulated method that receives different input variables 14, 15, and 16 and processes them to form the output variables 17 and 18 is implemented in the block 11. In the present example, the input variable 14 is a calculated pressure value for the pressure in the fuel delivery system. The input variable 15 corresponds to the current currently applied to the electric motor of the fuel delivery system. The input variable 16 is formed by the rotation speed of the fuel delivery pump or of the electric motor.

(7) Limit values for the volume that can be delivered are ascertained from the input variables in the submethod formed by the block 11. The output variable 17 represents the minimum delivery volume, while the output variable 18 represents the maximum delivery volume.

(8) The two output variables 17, 18 are firstly processed further in downstream units, such as the evaluation unit for example, and secondly also routed along the signal lines 19, 20 to the blocks 12, 13, as illustrated in FIG. 2. The output variables 17, 18 of the block 11 therefore form input variables for the blocks 12 and 13. In addition, the input variable 14 is also supplied to the blocks 12, 13. A conclusion can be drawn from the minimum and the maximum delivery volume, with the inclusion of the input variable 14, which reflects the calculated pressure value in the fuel delivery system, about a respectively required rotation speed of the electric motor or of the fuel delivery pump in order to be able to deliver the respective delivery volume.

(9) The result for the rotation speed for achieving the minimum delivery volume is output from block 12 as output variable 21. The rotation speed for achieving the maximum delivery volume is output as output variable 22 from block 13.

(10) FIG. 2 shows only a single exemplary illustration of an interconnection of individual submethods with one another. This is intended to illustrate the principle that individual submethods can be combined in series with one another or in parallel with one another in such a way that, by including additional control variables from other submethods, the quality of the ascertained control variables can be increased overall.

(11) FIG. 3 shows a further block diagram 30. A plurality of blocks 34, 35, 36, 37, 38, 39, 40, and 41, which respectively correspond to individual submethods, to an evaluation unit or to a calibration unit, are illustrated in the block diagram 30. A large number of signal lines, which show how the individual submethods and units can be networked with one another, are illustrated between the blocks 34 to 41. The illustration of the block diagram 30 is merely exemplary and is not of a limiting nature, particularly in respect of the number of submethods used or the interconnection of the submethods with one another.

(12) Input variables are supplied to the system shown by the blocks 31 and 32, and an output variable is drawn by the block 33 and then passed to the electric motor.

(13) Block 34 represents a sensor-free pressure detection operation that draws conclusions about the pressure in the fuel delivery system from measurement values. To this end, the rotation speed of the fuel delivery pump and the current intensity applied to the electric motor can be used for example. The submethod 34 draws the required input variables by the block 31.

(14) The block 35 represents a fuel monitoring operation in the example of FIG. 3. Measurement values from the block 32 and the pressure ascertained in the block 34 are input into the fuel delivery system as input variables. In particular, external state variables, which allow a statement to be made about the operating state of the motor vehicle and the environmental conditions of said motor vehicle, are supplied to the block 35 from block 32. The output variables from block 35 include, in particular, a volume signal, which reflects the quantity of fuel required, and a demand signal, which can be sent to the fuel delivery system or the fuel delivery pump as a request.

(15) The block 36 forms a calibration unit. The calibration unit serves to calibrate the values and signals detected by it, in order to eliminate undesired influences and inaccuracies. Examples of the input variables of the calibration unit are the data from the fuel delivery pump from block 31, the external state variables from block 32, the volume signal from block 35 and the ascertained pressure from block 34. These values can be calibrated in accordance with the stored calibration mechanisms. From block 36, the calibrated values can be passed on to downstream submethods.

(16) Block 37 represents a physical model which outputs, in particular, rotation speed prespecifications and rotation speed demands on the basis of a plurality of input variables. The input variables include the pressure ascertained in the block 34, the external state variables from block 32 and the data relating to the fuel delivery pump originating from block 31.

(17) Block 38 forms a volume-controlled submethod. It uses, for example, the external state variables from block 32, the data relating to the fuel delivery pump 31 and also the pressure ascertained in block 34 as input variables. An output variable is, for example, a rotation speed demand in order to achieve or maintain the desired delivery volume.

(18) The block 39 represents a characteristic map-based submethod. It receives a pressure value and a volume variable as input variables. A rotation speed is output as output variable from said input variables based on the fuel volume required.

(19) The output variables of the blocks 34 to 39 are supplied, amongst others, to the blocks 40 and 41. The block 40 forms an evaluation unit which monitors the input variables passed to it, in order to identify any deviations and implausibilities which may arise and to trigger an emergency program if required.

(20) Block 41 likewise forms an evaluation unit which finally assesses and possibly weights the generated signals, which are passed to the block 41 in the form of input variables, before selected signals are output to the block 33. A final control signal is output to the block 33. This control signal is generated on the basis of the output variables or control signals generated by the submethods in the various blocks 34 to 39, and represents a control command for the electric motor of the fuel delivery pump.

(21) In one advantageous refinement, the blocks 40 and 41 can together also form a common evaluation unit which contains all of the functionalities of the two blocks 40, 41.

(22) The method shown in the block diagram 30 can be repeatedly implemented in any desired number of loops in order to ensure continuous regulation of the electric motor or the fuel delivery pump. The block diagram 30 is merely exemplary and is highly simplified. It serves to support the concept of the invention and expressly is not of a limiting nature.

(23) Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.