Method for regulating a fuel feed pump

Abstract

A method for operating a fuel feed pump, the fuel feed pump having a pump system and an electrically commutated electric motor, the pump system being drivable by the electric motor, includes: detecting fluctuation in circular motion of the pump system over a rotational speed of the pump system to obtain a value of the fluctuation; standardizing the detected value of the fluctuation to obtain a standardized valise; and in a case in which a predefinable limit is exceeded by the standardized value, limiting a gradient of change in the rotational speed of the pump system.

Claims

1. A method for operating a fuel feed pump assembly, the fuel feed pump assembly having a rotary pump and an electrically commutated electric motor, the pump being drivable by the electric motor, the method comprising: detecting fluctuation in circular motion of the rotary pump over a rotational speed of the rotary pump to obtain a detected value of the fluctuation; standardizing the detected value of the fluctuation to obtain a standardized value; and taking countermeasures that limit a gradient of change in the rotational speed of the rotary pump, in a case in which a predefinable limit is exceeded by the standardized value.

2. The method as claimed in claim 1, wherein the detecting of the fluctuation in the circular motion of the rotary pump includes continuously detecting period lengths of the electrical commutation of the electric motor, wherein the detected period lengths of the electrical commutation are compared with period lengths of preceding electrical commutations, the difference between the compared period lengths being used to form the value for the fluctuation in the circular motion of the rotary pump.

3. The method as claimed in claim 2, wherein the difference is detected by comparing a detected period length of the electrical commutation with a mean value generated from a multiplicity of preceding period lengths of the electrical commutation.

4. The method as claimed in claim 2, wherein the comparison of the detected period length of the electrical commutation with the period lengths of preceding electrical commutations takes place at a constant rotational speed.

5. The method as claimed in claim 1, wherein the detecting of the fluctuation in the circular motion and the standardizing of the detected value of the fluctuation take place on a continuous basis.

6. The method as claimed in claim 1, wherein the gradient of the change in the rotational speed of the rotary pump is limited as a function of the rotational speed of the rotary pump.

7. The method as claimed in claim 1, further comprising passing on the standardized value of the fluctuation in the circular motion and/or the rotational speed of the rotary pump to an entity external to the rotary pump.

8. The method as claimed in claim 1, further comprising triggering an automatic system check at predefinable time intervals, the automatic system check comprising: varying the rotational speed of the rotary pump to one or more levels that differ from a current actual state, detecting the fluctuation in the circular motion of the rotary pump, and standardizing the value of the fluctuation.

9. The method as claimed in claim 1, further comprising detecting a load torque over the rotation of the rotary pump, detecting fluctuation in the output torque of the electric motor, and determining fluctuation in circular motion of the rotary pump over the rotational speed from a superimposition of fluctuations of the torques.

10. The method as claimed in claim 1, wherein in a case in which there is a change in a predefined value of the rotational speed of the rotary pump, a limitation, dependent on the standardized value of the fluctuation in the circular motion, of a maximum permissible gradient of the change in the rotational speed is predefined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further developments of the present invention are described in the dependent claims and in the following description of the figures.

(2) In the text which follows, the invention will be explained in detail on the basis of exemplary embodiments and with reference to the drawings, in which:

(3) FIG. 1 shows a flow chart setting forth the method according to the invention; and

(4) FIG. 2 shows a flow chart setting forth an alternative configuration of the method according to the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(5) FIG. 1 shows a flow chart setting forth the method according to the invention. In block 1, detection of the fluctuation in the circular motion of the pump system takes place. This can take place, for example, as a result of the use of position sensors. In block 2 the value detected in block 1 is standardized to obtain a uniform variable that permits definitive information to be obtained about the degree of the fluctuations. Finally, in block 3 it is checked whether the detected and standardized value is above a limiting value. If this is the case, a signal is output along the arrow 4, which signal gives rise to a limitation of the gradient of the change in the rotational speed of the pump system.

(6) FIG. 2 shows a flow chart of a method configured in an alternative way. Here, in block 10 the period length of an electrical commutation of the electric motor is detected. This commutation is directly dependent on the rotational speed.

(7) In block 11 the detected period length is compared with a period length or with a multiplicity of period lengths of preceding electrical commutations. For this purpose, for example a mean value can also be formed from the preceding periods.

(8) The comparison value is standardized in block 12. In block 13 the standardized value is compared with a predefinable limiting value and finally a signal for limiting the gradient of the change in the rotational speed is output along the arrow 14 if the limiting value has been exceeded.

(9) The exemplary embodiments in FIGS. 1 and 2 do not, in particular, have a restrictive character and serve to illustrate the inventive step.

(10) Thus, while there have been 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.