Method and system for controlling fluid temperature in a hpp powered hydraulic system of an aircraft

Abstract

The present invention relates to a hydraulic system for an aircraft wherein the hydraulic system comprises: a hydraulic power pack comprising a motor, a hydraulic fluid reservoir and a hydraulic pump; at least one hydraulic consumer; a high pressure supply line for supplying hydraulic fluid at a higher pressure to the hydraulic consumer; and a low pressure return line for returning hydraulic fluid at a lower pressure from the hydraulic consumer. In order to enhance the functionality of the hydraulic system, the hydraulic system further comprises a heating device comprising a short-circuit line connecting the high-pressure supply line with the low-pressure return line and a heater valve for opening and closing the short-circuit line, and a control and monitoring unit. In order to provide temperature management, a method for automatically controlling fluid temperature includes the steps of: a) monitoring fluid temperature, and b) controlling a heater valve.

Description

Technical Field

[0001] The invention relates to a method for automatically controlling the temperature of a fluid in a hydraulic system of an aircraft, including a hydraulic power pack. Furthermore, the invention relates to a hydraulic system of an aircraft, a hydraulic power pack for such a hydraulic system, a control and monitoring unit for such a hydraulic system or such a hydraulic power pack, an aircraft equipped with a hydraulic system and / or a hydraulic power pack and / or a control and monitoring unit, and a computer program. Background Art

[0002] Hydraulic systems use fluid under pressure to drive machinery or move mechanical parts. Almost all aircraft use some hydraulic power components. In aircraft, a single hydraulic system or two or more hydraulic systems working in cooperation can be used to provide power for any or all of the following components: wheel brakes, front wheel steering, landing gear retraction / extension, flaps and slats, thrust reversers, spoilers / speed brakes, flight control surfaces, cargo door / loading ramps, etc. Usually, the hydraulic system includes a pressure generator in the form of a hydraulic pump, a hydraulic consumer in the form of a hydraulic drive "motor" (e.g., a rotary motor or a linear motor such as a hydraulic cylinder) that provides power for the hydraulic drive components, and a hydraulic distribution system (also referred to as a "hydraulic transmission system") that accommodates and conveys the fluid of the entire aircraft as required. In most aircraft on the market today, the hydraulic pump is installed on the engine accessory gearbox and is powered when the engine is running.

[0003] Therefore, the hydraulic systems of today's aircraft are in continuous operation during all flight phases, thereby continuously generating heat. This is a rather passive process, ie the temperature is not actively controlled, and results in a wider operating temperature range, leading to oversizing of the hydraulic system.

[0004] Contrary to the most common solution of providing hydraulic pressure by means of a pump connected to the engine, the present invention relates to a hydraulic system in an aircraft powered by a hydraulic power pack, called HPP or HePP for electrically driven hydraulic power packs.

[0005] A hydraulic power pack (sometimes called a hydraulic power unit) is a self-contained system that generally comprises at least a motor pump and a fluid reservoir. The function of the hydraulic power pack is to apply the hydraulic pressure (and flow) required to drive hydraulic consumers such as motors, cylinders and other complementary components of a given hydraulic system. One advantage of such a hydraulic power pack is that the hydraulic power pack can be arranged in situ near the hydraulic consumers and can be powered electrically, so that no large hydraulic fluid distribution lines are required. Another advantage is that a hydraulic system comprising a hydraulic power pack can be powered on demand, i.e. the power pack can be switched off during certain flight phases and switched on only when consumers require it. Summary of the invention

[0006] The object of the present invention is to further enhance the functionality of a hydraulic system comprising a hydraulic power pack.

[0007] To achieve this object, the present invention provides a method according to claim 1 .

[0008] A hydraulic system, a hydraulic power pack and a control and monitoring unit configured to carry out the steps of the method, and a computer program with corresponding instructions are the subject matter of further independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0009] According to a first aspect of the present invention, there is provided a method for automatically controlling the temperature of a fluid in a hydraulic system of an aircraft, wherein the hydraulic system comprises: a hydraulic power pack including a motor, a hydraulic fluid reservoir and a hydraulic pump;

[0010] at least one hydraulic consumer;

[0011] a high-pressure supply line for supplying hydraulic fluid at a relatively high pressure to the hydraulic consumer;

[0012] a low-pressure return line for returning hydraulic fluid at a lower pressure from the hydraulic consumer;

[0013] a heating device including a short-circuit line connecting the high-pressure supply line with the low-pressure return line and a heater valve for opening and closing the short-circuit hydraulic line; and

[0014] Control and monitoring unit, wherein the fluid temperature is controlled by:

[0015] a) monitor fluid temperature, and

[0016] b) Control the heater valve.

[0017] According to some embodiments, the heating device is part of the hydraulic power pack. According to an alternative, the heating device is arranged outside the HPP, for example as part of the hydraulic conduction system of the hydraulic system. Furthermore, the hydraulic system may include a plurality of heating devices and a plurality of heater valves, for example one or more heater valves and short-circuit lines inside and / or outside the hydraulic power pack.

[0018] Preferably, step a) comprises the following steps:

[0019] a1) Measuring the fluid temperature of the hydraulic fluid in the hydraulic power pack.

[0020] Preferably, step a) comprises the following steps:

[0021] a2) Measuring the fluid temperature of the hydraulic fluid in the hydraulic fluid reservoir.

[0022] Preferably, step a) comprises the following steps:

[0023] a3) Measuring the fluid temperature of the hydraulic fluid in the high pressure supply line.

[0024] Preferably, step a) comprises the following steps:

[0025] a4) Measure the fluid temperature of the hydraulic fluid in the low pressure supply line.

[0026] Steps a2), a3) and a4) are preferred but may be omitted in some embodiments. In some embodiments, there is sufficient data to draw conclusions about the system temperature, for example by monitoring / measuring the fluid temperature in the reservoir and / or outlet, in particular if the heat capacity / heat transfer etc. is known.

[0027] Preferably, step a) comprises the following steps:

[0028] a5) Comparing the fluid temperature to lower and / or upper threshold values.

[0029] Preferably, step a) comprises the following steps:

[0030] a6) Determine whether the fluid temperature T is within the range of 0°C ≤ T ≤ 60°C.

[0031] Preferably, step a) comprises the following steps:

[0032] a7) Monitoring by means of a control and monitoring unit which is part of the aircraft-level computer and / or part of the control computer of the hydraulic power pack.

[0033] Preferably, step b) comprises the following steps:

[0034] b1) Controlling the heater valve to achieve a hydraulically shorter circuit from the high-pressure supply line to the low-pressure return line in order to heat the hydraulic fluid due to the resulting pressure difference.

[0035] Preferably, step b) comprises the following steps:

[0036] b2) Controlling a heater valve for controlling the flow through a short-circuit hydraulic line, or controlling a plurality of heater valves for controlling the flow through a plurality of short-circuit hydraulic lines.

[0037] Preferably, step b) comprises the following steps:

[0038] b3) Control by means of a control and monitoring unit which is part of the aircraft-level computer and / or part of the control computer of the hydraulic power pack.

[0039] Preferably, step b) comprises the following steps:

[0040] b4) Commanding the heater valve to open whenever the control and monitoring unit detects that the fluid temperature is below a defined first threshold.

[0041] Preferably, step b) comprises the following steps:

[0042] b5) Commanding the heater valve to close whenever the control and monitoring unit detects that the fluid temperature is above a defined second threshold.

[0043] Preferably, step b) comprises the following steps:

[0044] b6) Defining at least a lower threshold value as a function of a predetermined viscosity level of the hydraulic fluid.

[0045] Preferably, step b) comprises the following steps:

[0046] b7) Defining the temperature range of the hydraulic fluid according to the operating temperature range of components of the hydraulic system and / or the operating temperature range of the hydraulic fluid.

[0047] Preferably, step b) comprises the following steps:

[0048] b8) Control the heater valve to ensure that the heating function is enabled until the fluid temperature is within the expected range.

[0049] Preferably, step b) comprises the following steps:

[0050] b9) Control the heater valve to ensure that the heating function is stopped in the event of overtemperature.

[0051] Preferably, the method further comprises the following steps:

[0052] c) monitoring flight-related data in order to determine the actual flight phase or ground phase status of the aircraft and performing steps a) and b) based on this determination.

[0053] Preferably, the method further comprises the following steps:

[0054] d) When the vehicle is on the ground and the fluid temperature continues to rise, heating is inhibited.

[0055] Preferably, the method further comprises the following steps:

[0056] d1) In the event that the aircraft is in flight and the fluid temperature continues to rise, heating is inhibited.

[0057] Preferably, the method further comprises the following steps:

[0058] e) monitoring the trend of the fluid temperature, and performing step b) according to the trend of the fluid temperature.

[0059] Preferably, the method further comprises the following steps:

[0060] f) Recording the temperature of the fluid over time, comparing the actual temperature change over time with the previously recorded temperature change, and performing step b) based on the comparison.

[0061] Preferably, the method further comprises the following steps:

[0062] aa) activating the hydraulic power pack in response to a request from a hydraulic consumer and deactivating the hydraulic power pack when the hydraulic consumer does not require hydraulic power;

[0063] bb) monitoring the fluid temperature in the hydraulic power pack,

[0064] cc) optionally commanding an isolation valve to isolate the hydraulic consumer from the hydraulic power pack when the fluid temperature is below a predetermined threshold, commanding a heater valve disposed within the hydraulic power pack to open a shorter circuit for the hydraulic fluid within the hydraulic power pack, and operating a motor and a pump to heat the hydraulic fluid within the hydraulic power pack.

[0065] Isolation is the most preferred basic solution, while heating can also be performed without consumer isolation, so some embodiments do not provide consumer isolation. In a "power on demand" configuration, when there is no need to pressurize the system (no consumer activity), isolation is preferred. Preferred embodiments include this basic solution and other solutions (especially internal HPP heating) that are extensions of this basic solution.

[0066] According to a first alternative solution of the second aspect, the present invention also provides a hydraulic system for an aircraft, the hydraulic system comprising:

[0067] a hydraulic power pack comprising a motor, a hydraulic fluid reservoir and a hydraulic pump,

[0068] at least one hydraulic consumer,

[0069] a high-pressure supply line for supplying hydraulic fluid at a relatively high pressure to the hydraulic consumer,

[0070] a low-pressure return line for returning hydraulic fluid at a lower pressure from the hydraulic consumer,

[0071] a temperature sensor for sensing the fluid temperature of the hydraulic fluid,

[0072] a heating device comprising a short-circuit hydraulic line connecting the high-pressure supply line with the low-pressure return line and a heater valve for opening and closing the short-circuit hydraulic line, and

[0073] A control and monitoring unit is configured to control the heater valve according to the temperature of the fluid.

[0074] Preferably, the control and monitoring unit is configured to control the hydraulic system to perform the steps of the method according to any of the above-described embodiments.

[0075] According to a second alternative of the second aspect, the present invention provides a hydraulic power pack (HPP) for a hydraulic system of an aircraft, the hydraulic power pack comprising a motor, a hydraulic fluid reservoir, a hydraulic pump, a hydraulic output port for supplying hydraulic fluid at a higher pressure to a hydraulic consumer, a hydraulic input port for receiving hydraulic fluid at a lower pressure returned from the hydraulic consumer, a heating device comprising a short-circuit hydraulic line between the hydraulic output port and the hydraulic input port and a heater valve for opening and closing the short-circuit hydraulic line, a temperature sensor for sensing the temperature of the hydraulic fluid, and a control and monitoring unit configured to control the heater valve according to the fluid temperature.

[0076] In some embodiments, the HPP comprises one motor, in particular one motor pump. In some embodiments, the HPP comprises a plurality of motors, in particular a plurality of motor pumps.

[0077] Preferably, the control and monitoring unit is configured to control the hydraulic power pack to perform the steps of the method according to any of the above-described embodiments.

[0078] In some embodiments, the hydraulic power pack further comprises an isolation valve for isolating the output port from the pump, wherein the control and monitoring unit is configured to control the hydraulic power pack to perform a heating function for heating the hydraulic fluid within the hydraulic power pack by running the pump and opening the short-circuit line while the output port is isolated from the output port by the isolation valve.

[0079] Most preferably, the first alternative and the second alternative are combined, the hydraulic system of the first alternative being equipped with the hydraulic power pack of the second alternative.

[0080] Preferably, the hydraulic system further comprises an isolation valve for isolating the hydraulic consumer from the hydraulic group, wherein the control and monitoring unit is configured to control the hydraulic power group to perform a heating function for heating the hydraulic fluid in the hydraulic power group by running the pump and opening the short-circuit line while the hydraulic consumer is isolated from the hydraulic power group by the isolation valve.

[0081] According to a third aspect, the present invention provides a control and monitoring unit for a hydraulic system according to any of the above-mentioned embodiments of the hydraulic system or for a hydraulic power group according to any of the above-mentioned embodiments of the hydraulic power group, wherein the control and monitoring unit is configured to control and monitor the hydraulic system or the hydraulic power group to perform the steps of a method according to any of the above-mentioned embodiments of the method.

[0082] According to another aspect, the invention provides an aircraft comprising a hydraulic system and / or a hydraulic power pack and / or a control and monitoring unit according to any one of the above-described embodiments.

[0083] According to another aspect, the present invention provides a computer program comprising instructions for causing a hydraulic system or a hydraulic power pack according to any one of the above embodiments to perform the steps of a method according to any one of the above embodiments of the method.

[0084] The preferred embodiment of the present invention relates to a heating mode in a power pack application.

[0085] Some embodiments propose methods, systems, HPPs and / or units for providing a heating mode in a hydraulic system powered by a hydraulic power pack in an aircraft. For such a hydraulic system, thermal management has been evaluated and is considered beneficial. A preferred use of such a hydraulic system powered by at least one hydraulic power pack is a flight control architecture that relies primarily on electricity for powering flight controls (e.g., Airbus' "MEAC - More Electric Aircraft Control" project). One or preferably more HPPs may be part of such an architecture. Other preferred uses are hydrogen-powered aircraft such as the ZEROe - Airbus hydrogen-powered aircraft, or single-aisle aircraft such as the Airbus project NSA (Next Generation Single Aisle Aircraft).

[0086] In some embodiments, the hydraulic system powered by the HPP may be powered "on demand", ie the HPP may be shut down during certain flight phases or for longer periods within a flight phase and turned on only when required by the consumers.

[0087] Typically, hydraulic pumps require higher input power with cold fluids due to the higher viscosity of the fluid. Therefore, it is beneficial to ensure that the system temperature stabilizes at a temperature near the optimal operating point for the pump and consumers. In some embodiments, this is approximately 0°C to 60°C.

[0088] In some embodiments, the thermal management system allows this fluid temperature range to be maintained. In a preferred embodiment, the thermal management system allows the fluid temperature to be maintained within a narrower predetermined range around a given or determined optimal temperature for system operation. Thermal management results in reduced pressure drop at higher temperatures; therefore less power is required. The size of the distribution system (particularly pipes, hoses, fittings) can be kept smaller. Components work at more favorable operating points. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Embodiments of the present invention are explained below with reference to the accompanying drawings, in which:

[0090] Figure 1 is a schematic diagram of an aircraft including a hydraulic system powered by a hydraulic power pack; and

[0091] Figure 2 is a schematic simplified block diagram of an embodiment of a hydraulic system. DETAILED DESCRIPTION

[0092] Figure 1 An aircraft 10 is shown, which includes an aircraft-level control computer 11 and a hydraulic system 12. Figure 2 An example of a hydraulic system 12 is schematically shown in FIG.

[0093] The hydraulic system 12 comprises a hydraulic power pack 14, a distribution system 16 and hydraulic consumers 18. The hydraulic consumers 18 are, for example, hydraulic motors 20 or hydraulic cylinders 22. In particular, the hydraulic consumers 18 are actuators for driving components of the aircraft 10, such as flight control elements 24.

[0094] The hydraulic power pack 14 includes a motor 26, in particular an electric motor, a hydraulic fluid reservoir 28, a hydraulic pump 30, a hydraulic output port 32 for supplying hydraulic fluid at a higher pressure to the hydraulic consumer 18, and a hydraulic input port 34 for receiving hydraulic fluid at a lower pressure returned from the hydraulic consumer 18. In some embodiments, the hydraulic power pack 14 also includes an HPP control computer 36.

[0095] In the embodiment shown, the hydraulic system 12 further comprises a high-pressure supply line 38 for supplying hydraulic fluid at a higher pressure to the hydraulic consumer 18 , a low-pressure return line 40 for returning hydraulic fluid at a lower pressure from the hydraulic consumer 18 , a heating device 42 and a control and monitoring unit 43 .

[0096] The heating device 42 includes or consists of a short-circuit line 44 connecting the high-pressure supply line 38 with the low-pressure return line 40 and a heater valve 46 for opening and closing the hydraulic short-circuit line 44 .

[0097] In some embodiments, as indicated by the dashed line, the heating device 42 can be arranged inside the hydraulic power pack 14, wherein the short-circuit line 44 connects the HPP internal portion of the high-pressure supply line 38 with the HPP internal portion of the low-pressure return line 40, the HPP internal portion of the high-pressure supply line 38 connects the pump 30 with the output port 32, and the HPP internal portion of the low-pressure return line 40 connects the input port 34 with the fluid reservoir 28.

[0098] In some embodiments, as indicated by the dashed line, the heating device 42 can be arranged outside the hydraulic power group 14, wherein a short-circuit line 44 connects a distribution system portion of the high-pressure supply line 38 with a distribution system portion of the low-pressure return line 40, the distribution system portion of the high-pressure supply line 38 connects the output port 32 with one or more consumers 18, and the distribution system portion of the low-pressure return line 40 connects the consumer 18 with the input port 34.

[0099] In some embodiments, the hydraulic system 12 has both an internal heating device 42 and an external heating device 42 .

[0100] The control and monitoring unit 43 is a control computer comprising a processor 48 and a memory 50. The memory 50 contains a computer program with instructions for causing the hydraulic system to perform the method steps, as described in more detail below. The control and monitoring unit 43 may be (a part of) an aircraft-level control computer 11, (a part of) an HPP control computer 36 or may be a combination of several cooperating computers 11, 36.

[0101] Furthermore, the hydraulic system 12 comprises one or more temperature sensors 52 for determining the fluid temperature of the hydraulic fluid of the hydraulic system. The temperature sensor 52 is formed by any type of temperature transducer and is in communication connection with the control and monitoring unit 43. In some embodiments, the temperature sensor 52 or several of the temperature sensors 52 are arranged inside the HPP 14, in particular inside the fluid reservoir 28. The temperature sensor 52 may be arranged at any other point of the hydraulic system 14.

[0102] In some embodiments, the hydraulic system 12 further comprises one or more isolation valves 54 controlled by the control and monitoring unit 43. The isolation valves 54 are arranged and configured such that the consumer 18 can be isolated from the HPP 14.

[0103] Under the control of the control and monitoring unit 43 , the following method for controlling the temperature of the fluid in the hydraulic system 12 is automatically performed.

[0104] Fluid temperature in a hydraulic system is controlled by:

[0105] 1. Monitor fluid temperature (usually at the hydraulic reservoir 28)

[0106] 2. Heater valve 46

[0107] 3. Monitoring and control of heater valve 46

[0108] 4. Optional: Isolation valve 54

[0109] 1. Monitor fluid temperature:

[0110] Typically, for safety reasons (overheating), it is desirable to monitor the temperature of the fluid in a hydraulic system. The sensor 52 may be located in the hydraulic reservoir 28 or at another point in the hydraulic system 12 , typically inside the HPP 14 definition.

[0111] In particular, a conventional temperature transducer of "state of the art" design in a hydraulic system is used as the temperature sensor 52. The temperature transducer may be located in the hydraulic reservoir 28 or at another point in the system. In a preferred embodiment, the temperature sensor 52 is located inside the HPP 14. Monitoring is done by the aircraft-level computer 11 or directly at the HPP control computer 36.

[0112] 2. Heater valve 46

[0113] The heater valve 46 is a device inside the HPP 14 or at a different location in the hydraulic system 12 that enables a "shorter loop" from the high pressure supply line 38 to the low pressure return line 40. The pressure differential causes the fluid to heat up. Heating occurs due to losses.

[0114] There may be one or more heater valves 46 . The heater valves 46 are controlled by the aircraft level computer 11 or locally by the HPP control computer 36 .

[0115] Whenever the control and monitoring unit 43 detects that the temperature is below a first (lower) defined threshold, the heater valve 46 will be commanded to open, and when the temperature is above a defined second (higher) threshold, the heater valve 46 will be commanded to close. The first threshold and / or the second threshold are defined such that the first threshold and / or the second threshold ensure that the operating point of the motor pump unit and the system components is in the following conditions:

[0116] ● Viscosity values ​​that prevent excessive losses or power requirements, and / or

[0117] ●Prevent excessive wear of components or degradation of the fluid due to thermal loads to the fluid temperature.

[0118] Examples of threshold values ​​are 0°C and 60°C.

[0119] 3. Monitoring and control of heater valve 46

[0120] In some preferred embodiments, the control and monitoring unit 43 aims to achieve a certain target value (eg 30° C.). Below a threshold of 0° C., the control and monitoring unit 43 commands the heating function. Above 30° C., the heating function is commanded off.

[0121] The heater valve 46 is monitored and controlled to ensure that the heating mode function is enabled until the fluid temperature is within the expected range and to disable the heating mode if the temperature is too high.

[0122] The control and monitoring unit 43 monitors and controls the heater valve 46 to ensure that the heating mode is enabled until the fluid temperature is within the expected range and stops the heating mode when the temperature is too high. In addition, the fluid temperature is also monitored.

[0123] In some embodiments, the control and monitoring unit 43 may monitor flight-related data to take into account relevant flight phases: an example may be to inhibit heating to prevent overheating when the aircraft 10 is on the ground and the fluid temperature continues to rise. In some embodiments, heating is inhibited if the aircraft 10 is in flight and the fluid temperature continues to rise.

[0124] In some embodiments, the control and monitoring unit 43 is configured to perform trend monitoring and / or long-term logging to enable better prediction of system heating function and behavior.

[0125] 4. Isolation valve 54

[0126] In some embodiments, the following features are additionally provided.

[0127] The HPP 14 operates in an “on-demand” mode. In other words, the HPP 14 is activated only in case of demand from consumers, otherwise the HPP 14 is stopped.

[0128] When the HPP 14 is operating in the on-demand mode, the HPP internal heater valve 46 is enabled during flight phases when hydraulic power is not needed, for "internal mode" heating only. When the pump 30 of the HPP 14 is operating for internal mode heating, the isolation valve 54 ensures that the power generated by the HPP does not provide power to the hydraulic system 12, particularly the consumers 18. Instead, the heater valve 46 is used to heat the fluid volume within the HPP 14 and the HPP internal reservoir 28 (tank). When hydraulic power is later needed to provide hydraulic power to the consumers, this pre-heating will allow the system to operate at a temperature that allows higher performance.

[0129] In some embodiments, the on-demand mode and the internal heating mode are automatically performed by the following steps:

[0130] aa) activating the hydraulic power pack 14 in response to a request from the hydraulic consumer 18 and deactivating the hydraulic power pack 14 when the hydraulic consumer 18 does not require hydraulic power;

[0131] bb) monitoring the fluid temperature in the hydraulic power pack 14,

[0132] cc) when the temperature of the fluid in the HPP 14 is below a predetermined threshold, commanding the isolation valve 54 to isolate the hydraulic consumer 18 from the hydraulic power pack 14, commanding the heater valve 46 disposed within the hydraulic power pack 14 to open a shorter circuit for the hydraulic fluid inside the hydraulic power pack 14, and operating the motor 26 and the pump 30 to heat the hydraulic fluid inside the hydraulic power pack 14.

[0133] like Figure 2 As shown, the isolation valve 54 can be located inside the HPP 14 and / or on an external portion of the high pressure supply line 38. In some embodiments, the isolation valve 54 within the HPP 14 is disposed between the short circuit line 44 and the output port 32. In some embodiments (not shown), the isolation valve 54 and the heater valve 44 are combined into a multi-way valve.

[0134] An advantage of this embodiment with an internal heating mode is that once the hydraulic system 12 is pressurized, the warm fluid stored in the reservoir 28 will flow into the distribution system 16, thereby quickly heating the distribution system 16 and the consumers 18. In addition, the mixture of cold distribution system fluid and warm HPP internal fluid will produce an average temperature in the reservoir 28 that is higher than the (cold) system fluid temperature, thereby allowing the pump 30 in the HPP 14 to be operated at an operating point that requires less power.

[0135] A method and system for controlling the temperature of a fluid in a hydraulic system 12 of an aircraft 10 powered by a HPP 14 has been described. In particular, a hydraulic system 12 for an aircraft 10 has been described, the hydraulic system 12 comprising: a hydraulic power pack 14 comprising a motor 26, a hydraulic fluid reservoir 28 and a hydraulic pump 30; at least one hydraulic consumer 18; a high-pressure supply line 38 for supplying hydraulic fluid at a higher pressure to the hydraulic consumer 18; and a low-pressure return line 40 for returning hydraulic fluid at a lower pressure from the hydraulic consumer 18. To enhance functionality, the hydraulic system 12 further comprises a heating device 42 comprising a short-circuit line 44 connecting the high-pressure supply line 38 with the low-pressure return line 40 and a heater valve 46 for opening and closing the short-circuit line 44, as well as a control and monitoring unit 43. To provide temperature management, a method for automatically controlling the temperature of a fluid comprises the following steps:

[0136] a) monitor fluid temperature, and

[0137] b) Control the heater valve 46.

[0138] Reference numerals

[0139] 10 Aircraft 11 Aircraft-level control computer 12 Hydraulic system 14 Hydraulic power pack (HPP)

[0140] 16 Distribution System

[0141] 18 Hydraulic consumer

[0142] 20 Hydraulic motor

[0143] 22 Hydraulic cylinder

[0144] 24 flight control elements

[0145] 26 (Electric) Motor

[0146] 28 Storage

[0147] 30 pumps

[0148] 32 output ports

[0149] 34 Input ports

[0150] 36HPP control computer

[0151] 38 High pressure supply line

[0152] 40 low pressure return line

[0153] 42 Heating device

[0154] 43Control and monitoring unit

[0155] 44 short circuit pipeline

[0156] 46 Heater valve

[0157] 48 processors

[0158] 50 Memory

[0159] 52 Temperature Sensor

[0160] 54 Isolation valve.

Claims

1. A method for automatically controlling the temperature of a fluid in a hydraulic system (12) of an aircraft (10), wherein: The hydraulic system (12) includes: a hydraulic power pack (14), the hydraulic power pack (14) including a motor (26), a hydraulic fluid reservoir (28) and a hydraulic pump (30); at least one hydraulic consumer (18); a high-pressure supply line (38) for supplying the hydraulic consumer (18) with hydraulic fluid at a relatively high pressure; a low-pressure return line (40) for returning hydraulic fluid at a lower pressure from the hydraulic consumer (18); a heating device (42), the heating device (42) comprising a short-circuit line (44) connecting the high-pressure supply line (38) with the low-pressure return line (40) and a heater valve (46) for opening and closing the short-circuit line (44); and A control and monitoring unit (43), wherein the fluid temperature is controlled by: a) monitoring the temperature of the fluid, and b) Controlling the heater valve (46).

2. The method according to claim 1, characterized in that Step a) includes at least one or more of the following steps: a1) measuring the fluid temperature of the hydraulic fluid in the hydraulic power pack (14), a2) measuring the fluid temperature of the hydraulic fluid in the hydraulic fluid reservoir (28), a3) measuring the fluid temperature of the hydraulic fluid in the high pressure supply line (38), a4) measuring the fluid temperature of the hydraulic fluid in the low pressure supply line (40), a5) comparing the fluid temperature to lower and / or higher threshold values, a6) determining whether the fluid temperature T is within the range of 0°C ≤ T ≤ 60°C, a7) Monitoring is performed by means of the control and monitoring unit (43), which is part of the aircraft-level computer (11) and / or part of the control computer (36) of the hydraulic power pack (14).

3. The method according to any one of the preceding claims, characterized in that Step b) includes one or more of the following steps: b1) controlling the heater valve (46) to achieve a hydraulically shorter circuit from the high-pressure supply line (38) to the low-pressure return line (40) so as to heat the hydraulic fluid due to the resulting pressure difference; b2) controlling a heater valve (46) for controlling flow through a short-circuit hydraulic line (44), or controlling a plurality of heater valves (46) for controlling flow through a plurality of short-circuit hydraulic lines (44); b3) said control is carried out by means of said control and monitoring unit (43), said control and monitoring unit (43) being part of an aircraft-level computer (11) and / or part of a control computer (36) of said hydraulic power pack (14); b4) commanding the heater valve (46) to open whenever the control and monitoring unit (43) detects that the fluid temperature is below a defined first threshold; b5) commanding the heater valve (46) to close whenever the control and monitoring unit (43) detects that the fluid temperature is higher than a defined second threshold; b6) defining at least a lower threshold value according to a predetermined viscosity level of said hydraulic fluid; b7) limiting the temperature range of the hydraulic fluid according to the operating temperature range of the components of the hydraulic system and / or the operating temperature range of the hydraulic fluid; b8) controlling the heater valve (46) to ensure that the heating function is enabled until the fluid temperature is within a desired range; b9) Controlling the heater valve (46) to ensure that the heating function is stopped if the temperature is too high.

4. The method according to any one of the preceding claims, further comprising at least one or more of the following steps: c) monitoring flight-related data in order to determine the actual flight phase or ground phase status of the aircraft (10) and performing steps a) and b) based on this determination; d) inhibiting heating while the aircraft (10) is on the ground and the temperature of the fluid continues to increase; d1) inhibiting heating when the aircraft (10) is in flight and the temperature of the fluid continues to rise; e) monitoring a trend of the fluid temperature, and performing step b) according to the trend of the fluid temperature; f) Recording the temperature of the fluid over time, comparing the actual temperature change over time with the previously recorded temperature change, and performing step b) based on the comparison.

5. The method according to any one of the preceding claims, further comprising the steps of: activating the hydraulic power pack (14) in response to a request from the hydraulic consumer (18) and deactivating the hydraulic power pack (14) when the hydraulic consumer does not require hydraulic power; monitoring the temperature of the fluid within the hydraulic power pack (14); When the fluid temperature is below a predetermined threshold, the isolation valve (46) is commanded to isolate the hydraulic consumer (18) from the hydraulic power pack (14), the heater valve (46) disposed within the hydraulic power pack (14) is commanded to open a shorter circuit for the hydraulic fluid within the hydraulic power pack (14), and the motor (26) and the pump (30) are operated to heat the hydraulic fluid within the hydraulic power pack (14).

6. A hydraulic system (12) for an aircraft (10), the hydraulic system (12) comprising: A hydraulic power pack (14) comprising a motor (26), a hydraulic fluid reservoir (28) and a hydraulic pump (30), at least one hydraulic consumer (18), a high-pressure supply line (38) for supplying the hydraulic consumer (18) with hydraulic fluid at a relatively high pressure, a low-pressure return line (40) for returning hydraulic fluid at a lower pressure from the hydraulic consumer (18), a temperature sensor (52), the temperature sensor (52) being used to sense the fluid temperature of the hydraulic fluid, a heating device (42) comprising a short-circuit hydraulic line (44) connecting the high-pressure supply line (38) with the low-pressure return line (40) and a heater valve (46) for opening and closing the short-circuit hydraulic line (44), and A control and monitoring unit (43) is configured to control the heater valve (46) according to the fluid temperature.

7. The hydraulic system (12) according to claim 6, characterized in that The control and monitoring unit (43) is configured to control the hydraulic system (12) to perform the steps of the method according to any one of claims 1 to 5.

8. A hydraulic power pack (14), the hydraulic power pack (14) being used in a hydraulic system (12) of an aircraft (10), in particular in a hydraulic system (12) according to any one of claims 6 or 7, the hydraulic power pack (14) comprising: A motor (26); a hydraulic fluid reservoir (28); a hydraulic pump (30); a hydraulic output port (32) for supplying hydraulic fluid at a relatively high pressure to a hydraulic consumer (18); a hydraulic input port (34) for receiving hydraulic fluid at a relatively low pressure returned from the hydraulic consumer (18); a heating device (42) comprising a short-circuit hydraulic line (44) between the hydraulic output port (32) and the hydraulic input port (34) and a heater valve (46) for opening and closing the short-circuit hydraulic line (44); a temperature sensor (52) for sensing a hydraulic fluid temperature; and a control and monitoring unit (36, 43) configured to control the heater valve (46) in dependence on the fluid temperature.

9. The hydraulic power pack (14) according to claim 8, characterized in that: The control and monitoring unit (36, 43) is configured to control the hydraulic power pack (14) to perform the steps of the method according to any one of claims 1 to 5.

10. The hydraulic power pack (14) according to any one of claims 8 or 9, characterized in that: The hydraulic power pack (14) further comprises an isolation valve (54) for isolating the hydraulic output port (32) from the pump (30), wherein the control and monitoring unit (36, 43) is configured to control the hydraulic power pack (14) to perform a heating function for heating the hydraulic fluid in the hydraulic power pack (14) by running the pump (30) and opening the short-circuit line (44) while the output port (32) and the pump (30) are isolated by the isolation valve (54).

11. The hydraulic system (12) according to any one of claims 6 or 7, characterized in that The hydraulic power pack (14) is a hydraulic power pack according to any one of claims 8 to 10, and the hydraulic system (12) further comprises an isolation valve (54) for isolating the hydraulic consumer (18) from the hydraulic power pack (14), wherein the control and monitoring unit (36, 43) is configured to control the hydraulic power pack (14) to perform a heating function for heating the hydraulic fluid in the hydraulic power pack (14) by running the pump (30) and opening the short-circuit line (44) while the hydraulic consumer (18) is isolated from the hydraulic power pack (14) by the isolation valve (54).

12. A control and monitoring unit (36, 43), the control and monitoring unit (36, 43) being used for a hydraulic system (12) according to any one of claims 6, 7 or 11 or for a hydraulic power pack (14) according to any one of claims 8 to 10, the control and monitoring unit (36, 43) being configured to control and monitor the hydraulic system (12) or the hydraulic power pack (14) to perform the steps of the method according to any one of claims 1 to 5.

13. An aircraft (10) comprising a hydraulic system (12) according to any one of claims 6, 7 or 11 and / or a hydraulic power pack (14) according to any one of claims 8 to 10 or a control and monitoring unit (36, 43) according to claim 11.

14. A computer program comprising instructions causing a hydraulic system (12) according to any one of claims 6, 7 or 11 or a hydraulic power pack (14) according to any one of claims 8 to 10 to perform the steps of a method according to any one of claims 1 to 5.

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