Method and system for monitoring the operational state of a pump

Abstract

A method and a system for monitoring the operational state of a pump including acquiring a set characteristic diagram of the pump, the characteristic diagram of the pump being defined by a functional relationship between a first pump operating parameter characteristic of the operational state of the pump and a second pump operating parameter characteristic of the operational state of the pump. Subsequently, an actual characteristic diagram of the pump is acquired when the pump is installed in a higher-level system, in particular an aircraft system, and is running. Finally, the actual characteristic diagram of the pump is compared with the set characteristic diagram of the pump.

Claims

1. A method for monitoring the operational state of a pump comprising the steps: acquiring a set characteristic diagram of the pump, the characteristic diagram of the pump being defined by a functional relationship between a first pump operating parameter characteristic of the operational state of the pump and a second pump operating parameter characteristic of the operational state of the pump, acquiring an actual characteristic diagram of the pump when the pump is installed in a higher-level system of an aircraft, and is running, and comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump, the method including a further step of at least one of: one of periodically or continuously, for at least one predetermined value of the first pump operating parameter characteristic of the operational state of the pump, acquiring a difference between: a value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the sums on the actual characteristic diagram of the pump and a value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump, and also acquiring a progression over time of this difference, or one of periodically or continuously, for at least one predetermined value of the second pump operating parameter characteristic of the operational state of the pump, acquiring a difference between: a value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump, and a value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump and also acquiring a progression over time of this difference.

2. The method according to claim 1, wherein the characteristic diagram of the pump is defined by a functional relationship between an outlet volume flow of the pump and an outlet pressure of the pump.

3. The method according to claim 2, wherein at least one of the outlet volume flow of the pump is acquired by a flow sensor, and the outlet pressure of the pump is acquired by a pressure sensor.

4. The method according to claim 3, wherein the flow sensor comprises a non-invasive ultrasonic sensor.

5. The method according to claim 3, wherein the pressure sensor is located in the higher-level system.

6. The method according to claim 1, wherein the actual characteristic diagram of the pump is compared with the set characteristic diagram of the pump for at least one predetermined value of one of the first and the second pump operating parameter characteristics of the operational state of the pump, the predetermined value of the one of the first and the second pump operating parameter characteristics of the operational state of the pump being characteristic of one of a standard operation of the pump and a high-load operation of the pump.

7. The method according to claim 1, including a further step of at least one of: predicting a point in time when a repair or an exchange of the pump will be required on the basis of the progression over time of the difference between the value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and the value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump, and predicting a point in time when a repair or an exchange of the pump will be required on the basis of the progression over time of the difference between the value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and the value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump.

8. The method according to claim 1 used for monitoring the operational state of a pump which is installed in a hydraulic system of the aircraft.

9. A system for monitoring the operational state of a pump comprising: a device for acquiring a set characteristic diagram of the pump, the characteristic diagram of the pump being defined by a functional relationship between a first pump operating parameter characteristic of the operational state of the pump and a second pump operating parameter characteristic of the operational state of the pump, a device for acquiring an actual characteristic diagram of the pump when the pump is installed in a higher-level system of an aircraft, and is running, and a device for comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump, wherein the device for comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump is configured to at least one of: obtain, one of periodically or continuously, for at least one predetermined value of the first pump operating parameter characteristic of the operational state of the pump, a difference between a value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and a value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump, and also acquiring a progression over time of this difference, and obtain, one of periodically or continuously, for at least one predetermined value of the second pump operating parameter characteristic of the operational state of the pump a difference between a value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and a value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the desired characteristic diagram of the pump, and also acquiring a progression over time of this difference.

10. The system according to claim 9, wherein at least one of the device for acquiring a set characteristic diagram of the pump and the device for acquiring an actual characteristic diagram of the pump is designed to define the characteristic diagram of the pump by a functional relationship between an outlet volume flow of the pump and an outlet pressure of the pump.

11. The system according to claim 10, wherein at least one of at least one of the device for acquiring a set characteristic diagram of the pump and the device for acquiring an actual characteristic diagram of the pump, comprises a flow sensor for acquiring the outlet volume flow of the pump, and at least one of the device for acquiring a set characteristic diagram of the pump and the device for acquiring an actual characteristic diagram of the pump, comprises a pressure sensor for acquiring the outlet pressure of the pump.

12. The system according to claim 11, wherein the flow sensor comprises a non-invasive ultrasonic sensor.

13. The system according to claim 11, wherein the pressure sensor is located in the higher-level system.

14. The system according to claim 9, wherein the device for comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump is designed to compare the actual characteristic diagram of the pump with the set characteristic diagram of the pump, for at least one predetermined value of one of the first and second pump operating parameter characteristic of the operational state of the pump, the predetermined value of the one of the first and second pump operating parameter characteristic of the operational state of the pump being characteristic of one of a standard operation of the pump and a high-load operation of the pump.

15. The system according to claim 9, wherein at least one of the device for comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump is designed to predict a point in time when a repair or an exchange of the pump will be required on the basis of the progression over time of the difference between the value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and the value of the second pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the first pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump, or the device for comparing the actual characteristic diagram of the pump with the set characteristic diagram of the pump is designed to predict a point in time when a repair or an exchange of the pump will be required on the basis of the progression over time of the difference between the value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the actual characteristic diagram of the pump and the value of the first pump operating parameter characteristic of the operational state of the pump, which is assigned to the predetermined value of the second pump operating parameter characteristic of the operational state of the pump on the set characteristic diagram of the pump.

16. The system of claim 9 arranged to monitor the operational state of a pump in a hydraulic system of the aircraft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred embodiment of the invention will now be explained in more detail with the aid of the appended schematic drawings, of which

(2) FIG. 1 shows a flow chart of a method for monitoring the operational state of a pump,

(3) FIG. 2 shows a representation of a system for monitoring the operational state of a pump,

(4) FIG. 3 shows a graphical representation of various characteristic diagrams of a pump, and

(5) FIG. 4 shows a graphical representation of the result of a set/actual characteristic diagram comparison as a function of time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) A method and a system for monitoring the operational state of a pump are explained below with reference to a pump 10 which is arranged in a hydraulic fluid line 12 of an aircraft hydraulic system and serves to convey hydraulic fluid through the hydraulic fluid line 12 of the aircraft hydraulic system, see FIG. 2. The pump 10 may be configured, for example, in the form of an axial piston pump. It is understood, however, that the method and the system for monitoring the operational state of a pump may also be realized with a different pump.

(7) When the pump 10 is in a proper, intact operational state, internal leakages occur at various places inside the pump. These internal leakages are required for a proper operation of the pump 10, since they serve to lubricate and cool the pump 10. With increasing operating time of the pump 10, however, faults or wear phenomena lead to an excessive increase in the internal leakages, which have an adverse effect on the operational state, i.e., the operational reliability of the pump 10. The aim of the monitoring method and monitoring system described here is to monitor the operational state, i.e., the operational reliability of the pump 10 when the pump 10 is installed in the hydraulic system of the aircraft and is running, and thereby detect as early as possible reductions of the operational reliability of the pump 10.

(8) For this purpose, as illustrated in FIG. 1, in a first step a set characteristic diagram of the pump 10 is acquired first of all. The characteristic diagram of the pump 10 is defined by a functional relationship between two pump operating parameters characteristic of the operational state of the pump 10. The first pump operating parameter used here is an outlet volume flow of the pump 10 and the second pump operating parameter used here is an outlet pressure of the pump 10.

(9) The set characteristic diagram of the pump 10 reflects the operating performance of the pump 10 when the pump 10 is intact, i.e., the set characteristic diagram indicates the set relationship between the outlet volume flow and the outlet pressure of the pump 10 in the intact, i.e., nominal operational state of the pump. A device 14 for acquiring the set characteristic diagram comprises a storage unit, in which the pairs of values of the outlet volume flow and the outlet pressure of the pump 10 which constitute the set characteristic diagram are stored. These pairs of values may be prescribed by the manufacturer of the pump 10 or ascertained from a maintenance manual or the like. Alternatively to this, the set characteristic diagram of the pump 10 may also be measured. In the embodiment discussed here, this is possible, for example, by measuring the outlet pressure of the pump 10 at a varying outlet volume flow of the pump. Such measurements may be carried out on a separate pump test stand when the pump 10 is not installed in the higher-level hydraulic system of the aircraft. Alternatively to this, however, it is also possible to utilize a device 16, explained in more detail below, for acquiring an actual characteristic diagram of the pump 10 also for acquiring the set characteristic diagram of the pump 10.

(10) As already mentioned, a device 16 serves to acquire an actual characteristic diagram of the pump 10 when the pump 10 is installed in the higher-level hydraulic system of the aircraft and is running. The device 16 comprises a pressure sensor 18 which is arranged in the region of an outlet of the pump 10. The pressure sensor 18 may be a pressure sensor which is present anyway in the higher-level hydraulic system of the aircraft and serves, for example, to provide measurement data of the hydraulic fluid pressure in the hydraulic line 12 to a control unit (not shown in FIG. 2) for controlling the operation of the hydraulic system, which the control unit then uses to control the operation of the hydraulic system.

(11) Furthermore, the device 16 comprises a flow sensor 20 which is likewise arranged in the region of the outlet of the pump 10. The flow sensor 20 is a non-invasive ultrasonic sensor which is permanently placed in the region of the outlet of the pump 10 and therefore enables a continuous measurement of the outlet volume flow of the pump 10. Measurement data acquired by the sensors 18, 20 when the pump 10 is running are supplied to an electronic control unit 22. The electronic control unit 22 creates an actual characteristic diagram of the pump 10 from these measurement data. A graphical representation of the set characteristic diagram and of the actual characteristic diagram of the pump 10 is output on a display 24. The electronic control unit 22 and the display 24 thus form a device for comparing the set characteristic diagram of the pump 10 with the actual characteristic diagram of the pump 10.

(12) A set/actual characteristic diagram comparison may be carried out using the graphical representation of the set characteristic diagram and of the actual characteristic diagram of the pump 10 on the display 24. This set/actual characteristic diagram comparison enables conclusions to be drawn regarding the operational state, i.e., the operational reliability of the pump 10. This is explained in more detail below with reference to the graphical representation in FIG. 3.

(13) In the graph according to FIG. 3, the set characteristic diagram of the pump 10 is shown as a continuous line. The dashed line in the representation according to FIG. 3 illustrates an actual characteristic diagram A of the pump 10 which results when the operational state of the pump 10 has deteriorated compared with the nominal operational state of the pump 10, but is still acceptable. This is apparent by the fact that the actual characteristic diagram A lies over its entire course above a limit characteristic diagram, marked by a dash-dot line, which specifies the limit between a characteristic diagram course which is still acceptable and one which is no longer acceptable. By contrast, the dash-double-dot line in FIG. 3 shows an actual characteristic diagram B of the pump 10 which already lies over part of its course below the limit characteristic diagram. Finally, an actual characteristic diagram C of the pump 10 which lies over its entire course below the limit characteristic diagram is shown by a dotted line.

(14) If the actual characteristic diagram of the pump 10 lies over its entire course below the limit characteristic diagram, a repair or an exchange of the pump 10 is required. By contrast, if the actual characteristic diagram of the pump 10 lies only over part of its course below the limit characteristic diagram, a check can be done to see whether the pump 10 is operated frequently in an operating range in which the actual characteristic diagram lies below the limit characteristic diagram. If this is not the case and if the operating range of the pump 10 in which the actual characteristic diagram lies below the limit characteristic diagram is regarded as noncritical to the operation of the higher-level system in which the pump 10 is installed, the repair or the exchange of the pump 10 can optionally be postponed. Otherwise, a repair or an exchange of the pump 10 is necessary even if the actual characteristic diagram of the pump 10 lies only over part of its course below the limit characteristic diagram. In each case, however, a failure of the pump 10 and hence a failure of the higher-level system in which the pump 10 is installed is avoided.

(15) In principle, it is possible manually, i.e., solely on the basis of the overview diagram according to FIG. 3, to assess the operational state of the pump 10 and to determine whether the pump 10 can continue to be operated or whether a repair or an exchange of the pump 10 is required. Alternatively or additionally to this, however, it is also possible to select one predetermined value or a plurality of predetermined values of one of the two pump operating parameters defining the pump characteristic diagram, and consequently a specific section of the pump characteristic diagrams, for the set/actual characteristic diagram comparison and thus the assessment of the operational state of the pump 10.

(16) In the representation according to FIG. 3, a value AV1 of the outlet volume flow of the pump 10 represents a value of the outlet volume flow of the pump 10 which occurs in a frequently occurring standard operation of the pump 10 under normal load. By contrast, a value AV2 of the outlet volume flow of the pump 10 represents a value of the outlet volume flow of the pump 10 which occurs in a high-load operation of the pump 10. The operating performance of the pump 10 in the standard operation can be assessed by a set/actual characteristic diagram comparison for the value AV1. By contrast, a set/actual characteristic diagram comparison for the value AV2 enables an assessment of the operating performance of the pump 10 in the high-load operation. In particular, the actual characteristic diagram B in FIG. 3 shows that the operating performance of the pump 10 in the normal-load operation at AV1 may still be acceptable, whereas the operating performance of the pump 10 in the high-load operation at AV2 is no longer acceptable. This results from the fact that pump effects caused by wear or the like have a more pronounced effect in the high-load operation of the pump 10 than in the standard operation. A set/actual characteristic diagram comparison for the value AV2 therefore already provides early indications of slight deteriorations of the operational state of the pump 10.

(17) Furthermore, for a predetermined value of the outlet volume flow of the pump 10 which may correspond, for example, to the value AV1 or the value AV2, it is possible to determine periodically or continuously a difference between a pump outlet pressure value assigned to this value of the outlet volume flow on the actual characteristic diagram and an outlet pressure value assigned to this value of the outlet volume flow of the pump 10 on the set characteristic diagram. From such a difference determination, it is possible to create the representation according to FIG. 4 which shows the evolution over time of the difference between actual outlet pressure value and set outlet pressure value at a predetermined outlet volume flow. As long as the difference is positive, the actual outlet pressure value lies above the set outlet pressure value, from which it can be derived that the operational state of the pump 10 corresponds to or is better than the nominal operational state. By contrast, if the difference between actual outlet pressure value and set outlet pressure value at the predetermined outlet volume flow becomes negative, this indicates that the operational state of the pump 10 no longer corresponds to the nominal operational state, i.e., that a relevant deterioration of the operational state of the pump 10 compared with the nominal operational state has occurred. If the difference between actual outlet pressure value and set outlet pressure value exceeds a specific threshold value D.sub.crit, this can be judged to be an indication that the pump 10 must be repaired or exchanged.

(18) The representation according to FIG. 4 may, however, also be used, even before the threshold value D.sub.crit has been reached, to predict a point in time when a repair or an exchange of the pump 10 will be required. In particular, the course of the curve in FIG. 4 allows conclusions to be drawn regarding the speed with which the deterioration of the operational state of the pump 10 is occurring. The representations according to FIGS. 3 and 4 are created by the control unit 22 in the system illustrated in FIG. 2 and output on the display 24.

(19) As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.