Method for monitoring the condition of the hydraulic system

Abstract

The method for monitoring the condition of the hydraulic system for predicting the risk of failure is designed for hydraulic systems, whose components include at least one pump (1) for transporting fluid through the distribution system of the hydraulic system. The hydraulic system simultaneously detects at least one current magnitude of pressure and the current value of speed of the pump (1), whereupon the current speed value is compared with the trend speed value obtained from the statistically processed archived data of speed from the previous operation of the pump (1) and/or with the reference speed value of the pump (1), whereupon the comparison result provides the condition and risk of failure of the hydraulic system.

Claims

1. A method for monitoring the condition of a hydraulic system for predicting the risk of failure, whose components include a pump for transporting fluid through a distribution system of the hydraulic system, the method comprising: detecting at least one current magnitude of pressure in a hydraulic system and a simultaneous current speed value of the pump: performing at least one comparison, chosen from a group consisting of: comparing the current speed value with archived speed values from previous operation of the pump, said archived speed values having a corresponding, simultaneously detected magnitude of pressure similar to the current magnitude of pressure, and comparing the current speed value with a reference speed value of the pump, said referenced speed value having a simultaneously detected magnitude of pressure the current magnitude of pressure; whereupon the comparison result provides the condition and risk of failure of the hydraulic system; wherein the method further comprises: comparing the current magnitude of pressure in the hydraulic system -with a predefined threshold magnitude of pressure, wherein the archived speed value is recorded and archived from a moment of reaching the threshold magnitude of pressure, the threshold magnitude of pressure is set by means of a hydraulic switch included in the hydraulic system; recording an input power to the hydraulic system simultaneously with a closing of the hydraulic switch; calculating an output power of the hydraulic system for the predefined threshold magnitude of pressure; and calculating an efficiency of the hydraulic system from the input power and the output power.

2. The method of claim 1 wherein during calculating of the efficiency of the hydraulic system a differential hydraulic switch is used.

3. The method of claim 1 wherein during calculating the efficiency of the hydraulic system the viscosity of fluid is taken into account.

4. The method of claim 3 wherein during calculating the efficiency of the hydraulic system the current temperature of the fluid transported in the hydraulic system is detected and then the current viscosity of fluid is determined according to the measured current temperature.

5. The method of claim 1 wherein the viscosity of fluid is taken into account in determining the condition and risk of failure of the hydraulic system.

6. The method of claim 1 wherein the viscosity of fluid is taken into account in determining the condition and risk of failure of the hydraulic system.

7. The method of claim 2 wherein the viscosity of fluid is taken into account in determining the condition and risk of failure of the hydraulic system.

Description

EXPLANATION OF DRAWINGS

(1) The present invention will be explained in detail by means of the following figures where:

(2) FIG. 1 shows a schematic diagram of a hydraulic system,

(3) FIG. 2 shows a graph of current pump speed over time,

(4) FIG. 3 shows a graph of the values of current pump speed over time for different types of fluids,

(5) FIG. 4 shows a graph of the values of current pump speed over time for the rising fluid temperature.

EXAMPLE OF THE INVENTION EMBODIMENTS

(6) It shall be understood that the specific cases of the invention embodiments described and depicted below are provided for illustration only and do not limit the invention to the examples provided here. Those skilled in the art will find or, based on routine experiment, will be able to provide a greater or lesser number of equivalents to the specific embodiments of the invention which are described here. Also such equivalents will be included in the scope of the following claims.

(7) FIG. 1 shows a schematic diagram of a hydraulic system. The hydraulic system in this embodiment of the invention comprises at least one pump 1, which is connected via the fluid distribution system to the flow divider 4 that distributes the fluid to the individual nozzles 5 of the jet engine of the aircraft. The operation of the pump 1 is controlled by its control unit 2, which consists of control electronics comprising at least one communication interface for communication with external electronic device, e.g. sensors, control computer, indicator on the dashboard, etc., as well as at least one processor for running the control program, and furthermore at least one data storage for storing at least one software module and archiving the measurement data.

(8) There can be a variety of hydraulic systems and an expert will not have a problem to exchange one hydraulic system for another hydraulic system as part of his/her routine work. References in the example of embodiment of the invention to the hydraulic system in aviation engineering cannot be the only reason to limit the scope of protection of the invention.

(9) In this embodiment of the invention, the pump 1 is the fuel metering pump, which is used for metering fuel into nozzles 5 of the jet engines of the aircraft. The fuel metering pump includes an integrated control unit 2 and the hydraulic switch 3, which is set to the threshold pressure of 2 MPa. This threshold pressure is reached by the pump 1 at speed at the level of engine idle. The hydraulic switch 3 consists of the simple component, which comprises the resistive spring compressed by fluid pressure in the hydraulic system. When the spring is compressed, the pressure increased to the threshold value and the hydraulic switch 3 closes. Closing the hydraulic switch 3 sends an electrical signal to the control unit 2, which starts recording the speed of the pump 1. Speed measurement of the pump 1 takes place only after closing of the hydraulic switch 3.

(10) The invented method works by measuring the value of speed of the pump 1 for the current magnitude of pressure. When the measured speed is higher than it should be for the current magnitude of pressure, the fluid most probably leaks from the hydraulic system, because this pressure loss must be compensated by higher value of speed of the pump 1. From this condition of the hydraulic system, the risk of failure is assessed and therefore, the extra service inspection is ordered.

(11) If the measured speed of the pump 1 is lower than it should be for the current magnitude of pressure, the fluid most probably does not flow through the hydraulic system as it should and, therefore, the pressure is reached already at lower speed of the pump 1. The risk of failure of the hydraulic system is assessed and, therefore, the extra service inspection is ordered.

(12) Both of the above options for changing the speed are graphically illustrated in FIG. 2, which presents the speed of the pump 1 over past time, for example for threshold pressure of 2 MPa.

(13) The operating characteristics of the pump 1 changes with the number of the hours of operation worked, which is reflected in the trend of values obtained from the archived data from the previous operation. These trends of values are used to detect not only sudden changes indicating a risk of failure, but also to detect the successive non-standard changes indicating a risk of failure. Data and software module for determining the trend are stored in the control unit 2 of the pump 1.

(14) FIG. 3 shows a graph of influence of the type of fluid on speed of the pump 1. In one case, the fluid is the aviation fuel JP-4 and in the other case, the fluid is the aviation fuel JP-5. Furthermore, FIG. 4 shows a graph of influence of the action of the current temperature of fluid indicated by sensor 6 on speed of the pump 1.

(15) It is also possible to monitor the efficiency of the hydraulic system and track it in the trend with the increasing number of the hours of operation worked. The input power of the hydraulic system is measured at the moment of switching the detection of speed. Since speed detection is switched after reaching the defined pressure, the output power of the hydraulic system can be calculated. Then, the efficiency of the hydraulic system is determined using the formula for calculating the efficiency. Knowledge of the efficiency specifies the prediction of risk of failure of the hydraulic system.

INDUSTRIAL APPLICABILITY

(16) A method for monitoring the condition of the hydraulic circuit of the invention finds application in the transport industry, in particular in aviation engineering.

OVERVIEW OF THE INDEXES

(17) 1 pump 2 control unit 3 hydraulic switch 4 flow divider 5 nozzle 6 fluid temperature sensor