Indicator generating method and predictive maintenance method for failure prediction for a water heating system, such water heating system, and beverage maker

Abstract

An indicator generating method for generating an indicator which is suitable for maintenance prediction of a water heating system is proposed. A power state indication device generates a high power consumption signal if a heating device of the water heating system is activated. The time duration of the activation is such an indicator, if no water flow is present. Furthermore, the time interval between subsequent activations is such an indicator. A predictive maintenance method processes these condition-based indicators and determines a remaining useful lifetime according to a predictive maintenance model. The predictive maintenance device outputs a maintenance signal indicating required maintenance, if the remaining useful lifetime drops below a predetermined threshold. The methods may be performed by water heating systems or beverage makers.

Claims

1. An indicator generating method for generating an indicator which is suitable for maintenance prediction of a water heating system, the water heating system comprising a water tank containing water to be heated by a heating device, a power state indication device and a monitoring device, the method comprising: generating, via the power state indication device, at least a low power consumption signal or a high power consumption signal based on a power consumption of the heating device; determining, via the monitoring device, a condition-based degradation indicator based on a time duration of the high power consumption signal; outputting, via the monitoring device, the condition-based degradation indicator for further processing in a predictive maintenance device, wherein the monitoring device determines at least one of (1) a condition-based degradation indicator based on a time interval between two subsequent high power consumption signals and (2) a reheating frequency, which is a time interval between two subsequent high power consumption signals, and additionally outputs a reheating frequency as a condition-based degradation indicator.

2. The method according to claim 1, wherein the power state indication device includes a power measurement device which measures the power consumption caused by the heating device and generates at least one of: the high power consumption signal, if the power consumption exceeds a predetermined high power threshold, or the low power consumption signal, if the power consumption drops below a predetermined low power threshold.

3. The method according to claim 1, wherein the power state indicator device includes a communication interface which outputs a current water heating system state to an inter-device communications network, from which the monitoring device is able to obtain the current water heating system state and able to generate at least one of the low power consumption signal or high power consumption signal, depending on the obtained water heating system state.

4. The method according to claim 1, wherein the monitoring device determines a reheating time, which is a time duration of the high power consumption signal, and outputs the reheating time as a condition-based degradation indicator.

5. The method according to claim 1, wherein the water heating system comprises at least one additional sensor, wherein each additional sensor is configured for measuring at least one of an additional physical quantity and an ambient temperature, wherein the monitoring device additionally processes the measured quantity or temperature for generating the indicator.

6. The method according to claim 5, wherein the monitoring device determines a usage-based indicator based on at least one of sensor data or state information available on an inter-device communications network or the additional sensor.

7. The method according to claim 6, wherein the usage-based indicator includes at least one of a number of operation cycles, heating times, water quality, or water flows.

8. The method according to claim 1, wherein the water heating system comprises a water flow sensor which measures a presence of water flow to or from the tank, and the monitoring device at least one of: discards high power consumption signals as reheating cycle, if the water flow sensor detects presence of a water flow, additionally outputs water flow sensor data as a usage-based indicator.

9. A predictive maintenance method for generating a maintenance signal, which indicates that a water heating system monitored by a predictive maintenance device requires maintenance, the water heating system comprising a water tank containing water to be heated by a heating device, a power state indication device and a monitoring device, the method comprising: performing an indicator generating method according to claim 1, so as to generate at least a condition-based degradation indicator; determining, via the predictive maintenance device, a remaining useful lifetime based on the indicator from the previous step, by processing at least one of the condition- based degradation indicator or other indicators using a predictive maintenance model; outputting, via the predictive maintenance device, the maintenance signal, if the remaining useful lifetime or the condition based indicator or the usage based indicator drops below a predetermined threshold.

10. The method according to claim 9, wherein at least one of: the condition-based degradation indicator includes a reheating time, and the predictive maintenance device determines the remaining useful lifetime such that the remaining useful lifetime decreases, if the reheating time increases; the condition-based degradation indicator includes a reheating frequency, and the predictive maintenance device determines the remaining useful lifetime such that the remaining useful lifetime decreases, if the reheating frequency decreases; the condition-based degradation indicator includes at least one of an ambient temperature or water quality, and the predictive maintenance device determines the remaining useful lifetime such that the remaining useful lifetime decreases, if the predictive maintenance device determines that the reheating time is at least one of larger than, or the reheating frequency is smaller than, an expected value for at least one of the reheating time or reheating frequency, wherein the expected value is determined based on at least one of the ambient temperature or water quality.

11. A water heating system for a beverage maker of an aircraft galley, the water heating system configured for heating water and comprising: a water tank suitable to hold water to be heated, a heating device configured to heat the water within the water tank, a power state indication device configured to generate at least a low power consumption signal or a high power consumption signal based on a power consumption of the heating device; and a monitoring device configured to perform the indicator generating method according to claim 1.

12. A water heating system for a beverage maker of an aircraft galley, the water heating system configured for heating water and comprising: a water tank suitable to hold water to be heated, a heating device configured to heat the water within the water tank, a power state indication device configured to generate at least a low power consumption signal or a high power consumption signal based on a power consumption of the heating device; and a monitoring device configured to perform the predictive maintenance method according to claim 9.

13. A beverage maker for an aircraft galley comprising a water heating system according to claim 11.

14. A beverage maker for an aircraft galley comprising a water heating system according to claim 12.

15. A data medium containing instructions for a computer system, which, when executed by the computer system, performs the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are described in more detail with reference to the accompanying schematic drawings. Therein:

(2) FIG. 1 depicts an embodiment of a beverage maker according to the invention;

(3) FIG. 2 depicts another embodiment of a beverage maker according to the invention; and

(4) FIG. 3 is a diagram of different indicators.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) Referring to FIGS. 1 and 3, a beverage maker 10 is depicted. The beverage maker 10 is configured for a galley of an aircraft. The beverage maker 10 comprises a brewing assembly 12 for preparing hot beverages 14 from hot water. The brewing assembly 12 may be configured for preparing coffee or tea, for example.

(6) Furthermore, the beverage maker 10 includes a water heating system 16 which is configured for heating water. Preferably, the water heating system 16 is configured to keep the heated water within a predetermined temperature range.

(7) The water heating system 16 comprises a water tank 18 which is able to hold water 20 to be heated. The water tank 18 may have a thermal insulation so as to reduce heat dissipation from the water tank 18 to the environment.

(8) The water heating system 16 comprises a heating device 22. The heating device 22 is arranged within the water tank 18 so as to be able to heat the water 20.

(9) The water heating system 16 comprises a thermal sensor 24 for measuring the temperature of the water 20. The thermal sensor 24 can be integrated into the heating device 22. It is also possible that the thermal sensor 24 is configured separately or integrated in another suitable component of the water heating system 16.

(10) The water heating system 16 includes an inlet valve 26 which controls the inlet of fresh water into the water tank 18. Furthermore, the water heating system 16 includes an outlet valve 28 which controls the outlet of hot water to the brewing assembly 12.

(11) The water heating system 16 comprises one or more additional sensors 30. The additional sensor 30 may be select from a group containing ambient temperature sensors, water flow sensors, and water quality sensors.

(12) The water quality sensors may be configured for obtaining a water quality, by measuring physical parameters of the water 20, the physical parameters being indicative of the specific heat capacity of the water 20. As an example, the water quality sensor may be a TDS Sensor which measures the amount of total dissolved solids in the water 20.

(13) Two additional sensors 30 may be water flow sensors arranged close to or integrated in the inlet valve 26 and outlet valve 28, so as to be able to measure inflow and/or outflow.

(14) The water heating system 16 comprises a power supply line 32 with which the water heating system 16 is connected to a power supply 34. The power supply 34 is preferably provided by an aircraft on board power grid, for example.

(15) The water heating system 16 also includes a power state indication device 36, which is configured to generate a low power consumption signal LOPC and a high power consumption signal HIPC based on the power consumed by the water heating system 16, in particular, the heating device 22.

(16) The power state indication device 36 comprises a power measurement device 38, such as a power clamp 40 which is suitable for measuring power consumption without direct electrical contact to the power supply line 32.

(17) Thus, the low power consumption signal LOPC indicates that the heating device 22 is off, while the high power consumption signal HIPC indicates that the heating device 22 is active and heating the water 20.

(18) The water heating system 16 comprises a monitoring device 42. The monitoring device 42 is configured to monitor the water heating system 16. The monitoring device 42 may be implemented as a computer or microcontroller of some sort and perform various methods described below.

(19) Furthermore, the monitoring device 42 is connected to the power measurement device 38.

(20) The monitoring device 42 may be configured as a separate module.

(21) Furthermore, the monitoring device 42 need not be integrated into the beverage maker 10 or the water heating system 16. It is also possible for the monitoring device 42 to be arranged at a different location within the aircraft. The monitoring device 42 may be part of the power state indication device 36.

(22) The water heating system 16 comprises a control device or controller 43. The control device 43 is configured to control the water heating system 16 and possibly the beverage maker 10. The control device 43 is connected to the heating device 22 so as to switch the heating device 22 on and off to keep the water 20 within a known temperature range.

(23) The control device 43 is also connected to the inlet and outlet valves 26, 28 as well as the additional sensors 30.

(24) The monitoring device 42 and the control device 43 are presently described as being integrated into a single unit. It should be noted that the devices may be separate and not even within the vicinity of each other.

(25) At the beginning of operation of the water heating system 16 or the beverage maker 10, the control device 43 fills the water tank 18 via inlet valve 26 if necessary and activates the heating device 22 so as to heat the water 20.

(26) After this initial heating, the control device 43 measures the water temperature of the water 20 using thermal sensor 24. If the water temperature drops below a lower threshold, the heating device 22 is activated until the water temperature exceeds an upper threshold. Thus, the water temperature is kept within a predetermined temperature range. The process between two such subsequent activations of the heating device 22 is called a reheating cycle 44.

(27) The time duration for which the heating device 22 is activated, i.e., the high power consumption signal HIPC is active, is the reheating time 46. The reheating time 46 is determined by the monitoring device 42 by storing a first timestamp, when the power state indication device 36 changes from the low power consumption signal LOPC to the high power consumption signal HIPC, and a second time stamp, when the power state indication device 36 changes from the high power consumption signal HIPC to the low power consumption signal LOPC. The reheating time 46 is then determined by subtracting the first timestamp from the second time stamp. As an alternative, a timer may be used to measure the relevant time intervals instead of the timestamps.

(28) The reheating time 46 is stored as a condition-based degradation indicator for further processing. Alternatively or additionally, the reheating time 46 may be processed further directly.

(29) In addition, the monitoring device 42 may also determine the time interval between two subsequent reheating cycles 44. This time interval is called reheating frequency 48.

(30) The reheating frequency 48 is also stored as a condition-based degradation indicator for further processing. Alternatively or additionally, the reheating frequency 48 may be processed further directly.

(31) The following pseudo code outlines the principles of the determination in case that only a power based signal, e.g., in case of minimum instrumentation of legacy beverage makers, such as beverage maker 10, is available.

(32) This method is an approximation as the distinction between operating cycles and subsequent heating is not easily possible, unless, e.g., with additional water flow data, which can be acquired from a sensor integrated in the outlet valve 28, for example.

(33) TABLE-US-00001 // condition-based indicators list<time, float> reheating_times list<time, float> reheating_frequency // usage-based indicators list<time, int> brew_cycles list<time, int> tapping_cycles list<time, float> heating_time list<time, float> water_flow // constants to be defined per equipment model REHEATING_THRESHOLD BREW_CYCLE_TIME BREW_CYCLE_FLOW TAPPING_FLOW // feature extraction method for power for each timestep i // identify start of HIGH power consumption if (POWER_STATE(i-1) == LOW && POWER_STATE(i) == HIGH) start_time = current_time(i) //identify time between two consecutive reheating cycles if (last_cycle_type == ‘REHEATING’) add reheating_frequency(start_time, (start_time-stop_time)) // identify end of HIGH power consumption if (POWER_STATE(i-1) == HIGH && POWER_STATE(i) == LOW) stop_time = current_time(i) // identify duration of heating cycle cycle_time = stop_time - start_time add heating_time(start_time, cycle_time) // identify reheating cycles if (cycle_time < REHEATING_THRESHOLD) last_cycle_type = ‘REHEATING’ add reheating_times(start_time, cycle_time) // identify brew cycles (incl. subsequent heating) else if (cycle_time >  BREW_CYCLE_TIME) last_cycle_type = ‘BREW’ add brew_cycles(start_time, 1) add water_flow(start_time, BREW_CYCLE_FLOW) // identify tapping cycles (incl. subsequent heating) else if (cycle_time <BREW_CYCLE_TIME) last_cycle_type = ‘TAPPING’ add tapping_cycles(start_time, 1) add water_flow (start_time, TAPPING_FLOW * cycle_time)

(34) The water heating system 16 may also comprise a predictive maintenance device 50. The predictive maintenance device 50 may be formed as a single unit or by plurality of components. Furthermore, the predictive maintenance device 50 may be part of the beverage maker 10 or water heating system 16 or an external component.

(35) The predictive maintenance device 50 is configured to output a maintenance signal, which indicates that the water heating system 16 requires maintenance. The predictive maintenance device 50 may be integral with the monitoring device 42 or a separate device.

(36) Based on the condition-based degradation indicator and, if available usage-based indicators, the predictive maintenance device 50 determines an estimate remaining useful lifetime using a predictive maintenance model.

(37) The maintenance signal is output, if the remaining useful lifetime or the condition based indicator or the usage based indicator drops below a predetermined threshold. For example, the maintenance signal is output, if an increasing reheating time causes the remaining useful lifetime to drop below a number of hours that are smaller than the next flight segment. Furthermore, the maintenance signal may be output, if the reheating frequency drops below a predetermined reheating frequency threshold.

(38) It should be noted that the maintenance signal may also be configured to have different levels of urgency, e.g., “good for one more flight segment” and/or “out of order/maintenance required”.

(39) The maintenance signal may also include information about the type of expected fault, such as issues with the heating element 22 or insulation of the water tank 18 or possible leakage. The predictive maintenance device 50 may hence include a predictive maintenance model of the beverage maker 10 or the water heating system 16.

(40) FIG. 2 depicts another embodiment of a beverage maker 52 which is adapted for a modern inter-device communications network that is governed by a protocol such as ARINC 812. The beverage maker 52 therefore comprises a communication interface 54. The communication interface 54 is configured to process all kinds of state-related data communicated by the inter-device communications network.

(41) The beverage maker 52, more precisely the power state indication device 36, comprises a heater state communication interface 56. The heater state communication interface 56 outputs the state of the heating device 22 via the inter-device network. Thus no additional power measurement is necessary. Rather the heater state communication interface 56 is giving the current state (on or off) of the heating device 22.

(42) Then as described above, the monitoring device 42 may, e.g., store timestamps (and/or time intervals) accordingly in order to determine the reheating time and/or reheating frequency.

(43) Further useful data, such as the tap flow, etc., may be obtained via the communication interface 54, if available.

(44) The following pseudo code outlines the determination of condition-based degradation indicators if ARINC 812 data is available. This feature extraction method is improved compared to the power approach but may also include approximations, e.g., in case of aborted catering cycles which could be reduced by taking into account further ARINC 812 values or, e.g., with additional water flow data.

(45) TABLE-US-00002 // condition-based indicators list<time, float> reheating_times list<time, float> reheating_frequency // usage-based indicators list<time, int> brew_cycles list<time, int> tapping_cycles list<time, float> heating_time list<time, float> water_flow // constants to be defined per equipment model MINIMUM_TIME_VALUE_FOR_PBR CATERING_TIME_VALUE_FOR_PBR REHEATING_THRESHOLD BREW_CYCLE_TIME BREW_CYCLE_FLOW TAPPING_FLOW // feature extraction algorithm for ARINC 812 for each timestep i // identify start of heating cycle if(HEATER_STATE (i-1) == ‘STANDBY_ON’ && HEATER_STATE (i)  == ‘ON’) start_time = current_time(i) timer_for_pbr = current_timer_value(i) //identify time between two consecutive reheating cycles if (last_cycle_type == ‘REHEATING’) add reheating_frequency(start_time, (start_time - stop_time)) // identify end of heating cycle if (HEATER_STATE (i-1) == ‘ON’ && HEATER_STATE (i) ==  ‘FINISHED’) stop_time = current_time(i) // identify duration of heating cycle cycle_time = stop_time - start_time add heating_time(start_time, cycle_time) // identify reheating cycles if (timer_for_pbr == MINIMUM_TIME_VALUE_FOR_PBR &&  cycle_time < REHEATING_THRESHOLD) last_cycle_type = ‘REHEATING’ add reheating_times(start_time, cycle_time) // identify heating cycle following brew and/or tapping cycle if (last_cycle_type == ‘BREW’ || last_cycle_type == ‘TAPPING’ ||  last_cycle_type == ‘BREW/TAPPING’) last_cycle_type = ‘HEATING-UP’ // could be used to reverse calculate water inflow temperature etc. // identify brew cycles (excl. subsequent heating) else if (timer_for_pbr == CATERING_TIME_VALUE_FOR_PBR &&  cycle_time ~= BREW_CYCLE_TIME) last_cycle_type = ‘BREW’ add brew_cycles(start_time, 1) add water_flow(start_time, BREW_CYCLE_FLOW) // identify tapping cycles (excl. subsequent heating) else if (timer_for_pbr  == CATERING_TIME_VALUE_FOR_PBR && cycle_time <  BREW_CYCLE_TIME) last_cycle_type = ‘TAPPING’ add tapping_cycles(start_time, 1) add water_flow(start_time, TAPPING_FLOW * cycle_time) // identify combined brew and tapping cycles (excl. subsequent heating) else if (timer_for_pbr == CATERING_TIME_VALUE_FOR_PBR &&  cycle_time > BREW_CYCLE_TIME) last_cycle_type = ‘BREW/TAPPING’ add brew_cycles(start_time, 1) add tapping_cycles(start_time, 1) add water_flow(start_time, BREW_CYCLE_FLOW + (TAPPING_FLOW  * (cycle_time - BREW_CYCLE_TIME))

(46) The features obtained by the above outlined methods can serve as an input for prediction modelling methods either individually or in combination, e.g., the reheating time and frequency. Also, a cleaning of the feature data could be done, e.g., for removal of outliers.

(47) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE SIGNS

(48) 10 beverage maker 12 brewing assembly 14 hot beverage 16 water heating system 18 water tank 20 water 22 heating device 24 thermal sensor 26 inlet valve 28 outlet valve 30 additional sensor 32 power supply line 34 power supply 36 power state indication device 38 power measurement device 40 power clamp 42 monitoring device 43 control device 44 reheating cycle 46 reheating time 48 reheating frequency 50 predictive maintenance device 52 beverage maker 54 communication interface 56 heater state communication interface