Aircraft engine and method for operating an aircraft engine

Abstract

An aircraft engine includes at least one electrical apparatus, which can be driven by a driveshaft in order to generate electrical energy. A hydrodynamic torque converter, with guide blades, which can be adjusted via a mechanism, is arranged between the driveshaft and the electrical apparatus. The guide blades are adjusted as a function of a rotational speed of the driveshaft, wherein the rotational speed of a shaft of the electrical apparatus operated as a generator can be adjusted, essentially within a predefined rotational speed range, via the adjustment of the guide blades.

Claims

1. An aircraft engine comprising: a driveshaft; an electrical apparatus, driven by the driveshaft, to generate electrical energy, a hydrodynamic torque converter with adjustable guide blades arranged between the driveshaft and the electrical apparatus; an adjustment mechanism for adjusting a position of the guide blades; a coupling mechanism arranged between the driveshaft and a shaft of the electrical apparatus, via which a drive torque generated by the electrical apparatus when operated as a motor can be supplied in a direction of the driveshaft; wherein the coupling mechanism includes a switch element, via which the hydrodynamic torque converter can be bypassed during a starting sequence performed by the drive torque generated by the electrical apparatus.

2. The aircraft engine in accordance with claim 1, wherein the electrical apparatus can be driven via an accessory generator with a drive train providing the torque.

3. The aircraft engine in accordance with claim 1, and further comprising: a transmission mechanism having an output shaft, wherein the hydrodynamic torque converter further includes an impeller, wherein the transmission mechanism is arranged between the driveshaft and the impeller, wherein the impeller is connected to the output shaft.

4. The aircraft engine in accordance with claim 3, wherein the hydrodynamic torque converter includes a turbine wheel and the turbine wheel is in operative connection with the shaft of the electrical apparatus.

5. The aircraft engine in accordance with claim 3, wherein an oil circulation of the hydrodynamic torque converter is operatively connected to an oil circulation of the electrical apparatus.

6. The aircraft engine in accordance with claim 1, wherein the switch element of the coupling mechanism is a freewheel arranged between the shaft of the electrical apparatus and the impeller, which connects the shaft and the impeller torque-proof to one another when there is a positive rotational speed difference between a rotational speed of the shaft of the electrical apparatus and a rotational speed of the impeller, while the shaft and the impeller in an area of the freewheel are decoupled from one another when there is a negative rotational speed difference.

7. The aircraft engine in accordance with claim 6, wherein an oil circulation of the hydrodynamic torque converter is operatively connected to an oil circulation of the electrical apparatus.

8. The aircraft engine in accordance with claim 1, wherein the switch element of the coupling mechanism is a torque converter lock-up clutch.

9. The aircraft engine in accordance with claim 1, wherein an oil circulation of the hydrodynamic torque converter is connected to an oil circulation of the aircraft engine.

10. The aircraft engine in accordance with claim 1, wherein an oil circulation of the hydrodynamic torque converter is operatively connected to an oil circulation of the electrical apparatus.

11. A method of operating an aircraft engine, comprising: providing an aircraft engine comprising: a driveshaft; an electrical apparatus including a shaft, driven by the driveshaft, to generate electrical energy, a hydrodynamic torque converter with adjustable guide blades arranged between the driveshaft and the shaft of the electrical apparatus, an adjustment mechanism for adjusting a position of the guide blades, adjusting the guide blades as a function of a rotational speed of the driveshaft, and adjusting a rotational speed of the shaft of the electrical apparatus when operated as a generator within a predefined rotational speed range via the adjusting of the guide blades.

12. The method in accordance with claim 11, and further comprising adjusting the guide blades to comply with a constant rotational speed of the shaft of the electrical apparatus operated as a generator as a function of an effective rotational speed of the driveshaft.

13. The method in accordance with claim 12, and further comprising reducing the rotational speed of the driveshaft in an area between the driveshaft and the torque converter to a level of rotational speed at which the hydrodynamic torque converter and the electrical apparatus can be operated with a high level of efficiency.

14. The method in accordance with claim 11, and further comprising reducing the rotational speed of the driveshaft in an area between the driveshaft and the torque converter to a level of rotational speed at which the hydrodynamic torque converter and the electrical apparatus can be operated with a high level of efficiency.

15. An aircraft engine comprising: a driveshaft; an electrical apparatus, driven by the driveshaft, to generate electrical energy, a hydrodynamic torque converter with adjustable guide blades arranged between the driveshaft and the electrical apparatus; an adjustment mechanism for adjusting a position of the guide blades; wherein an oil circulation of the hydrodynamic torque converter is connected to an oil circulation of the aircraft engine.

16. An aircraft engine comprising: a driveshaft; an electrical apparatus, driven by the driveshaft, to generate electrical energy, a hydrodynamic torque converter with adjustable guide blades arranged between the driveshaft and the electrical apparatus; an adjustment mechanism for adjusting a position of the guide blades; wherein an oil circulation of the hydrodynamic torque converter is operatively connected to an oil circulation of the electrical apparatus.

Description

(1) Further advantages and advantageous embodiments of the aircraft engine according to the invention follow from the present description with reference to the drawings.

(2) In the drawings:

(3) FIG. 1 is a highly schematized profile view of an aircraft engine; and

(4) FIG. 2 is an enlarged view of the area II in FIG. 1, labeled in more detail.

(5) FIG. 1 depicts a section view of an aircraft engine 1, which has an electrical apparatus 2 in a lower area for the generation of electrical energy. Here, the electrical apparatus 2 is designed as an alternating current apparatus, which can be operated both as a generator and as a motor, and to which torque can be supplied by a driveshaft 20 (see FIG. 2) of the aircraft engine 1 in order to generate electrical energy in operation as a generator. The driveshaft 20 is connected to a high-pressure turbine of the aircraft engine 1, wherein the torque in the area of the driveshaft can be transferred, in an appropriately altered magnitude, via a transmission 3, depicted in more detail in FIG. 2 and a hydrodynamic torque converter 4 on a shaft 5 of the electrical apparatus 2. Here, the transmission 3 incorporates three spur gears 6 to 8, in mesh with one another. An impeller 9 of the hydrodynamic torque converter 4 is in operative connection with the spur gear 8 and transfers torque in contact with the impeller 9 via the spur gear 8 to a turbine wheel 11 of the hydrodynamic torque converter 4 according to a characteristic of the hydrodynamic torque converter 4 and via a hydraulic fluid and adjustable guide blades 10 in place inside the hydrodynamic torque converter 4, which impeller 9 is connected torque-proof to the shaft 5 of the electrical apparatus 2. The shaft, in turn, is coupled torque-proof to a rotor 18 of the electrical apparatus 2, which works in concert with a stator 19 of the electrical apparatus 2 in the usual manner.

(6) A coupling mechanism 12 is arranged between the impeller 9 of the hydrodynamic torque converter 4 and the shaft 5 of the electrical apparatus 2, which incorporates a switch element 13, via which the hydrodynamic torque converter 4 can be bypassed during a starting sequence performed by means of a drive torque generated by the electrical apparatus 2 of the aircraft engine 1. For this purpose, for example, it can be arranged that the electrical apparatus 2 then operated as a motor is energized by an external power source on a taxiway of an airport and the drive torque required for the aircraft engine is generated, which is then directly conducted to the impeller 9 by the shaft 5 via the switch element 13 on hand, designed as a freewheel, of the coupling mechanism 12 and is conducted from there in the direction of the driveshaft of the aircraft engine 1 via the transmission 3.

(7) For this purpose, the freewheel 13 locks when there is a positive rotational speed difference between the rotational speed of the shaft 5 of the electrical apparatus 2 and the rotational speed of the impeller 9, and connects the shaft 5 and the impeller 9 together torque-proof, while the shaft 5 and the impeller 9 in the area of the freewheel 13 are decoupled from one another when there is a negative rotational speed difference.

(8) The direct mechanical drive on hand in the area of the freewheel 13 on startup provides a significant advantage since the electrical apparatus 2 in operation as a generator can be utilized at maximal rotational speeds and a lower starting torque can be provided via the electrical apparatus 2 while in operation as a motor on starting the aircraft engine 1. Hence, the efficiency of the starting sequence can be improved with an electrical apparatus 2, designed to be both smaller in size and have a lower weight.

(9) In the present case, the guide blades 10 are adjusted via an adjustment mechanism 14 so that, in spite of the varying rotational speed of the driveshaft of the aircraft engine 1, the shaft 5 rotates with an essentially constant rotational speed in order to generate a consistent voltage and a consistent frequency, wherein the electrical energy generated in the area of the electrical apparatus 2 during operation as a generator is transmitted via wiring 15 to electrical loads in the area of an aircraft provided with the aircraft engine.

(10) The gear ratio of the transmission 3 and the resulting rotational output speed of the hydrodynamic torque converter 4 are selected as a function of the efficiency of the hydrodynamic torque converter 4 and the characteristics of the rotational speed ratios, wherein the transmission 3 is actually a part of a gearbox of an accessory generator 22 of the aircraft engine 1. In order to generate electrical energy via the electrical apparatus 2, the impeller 9 should be operated with a higher rotational speed than the turbine wheel 11 since only in this case can torque be transmitted from the driveshaft of the aircraft engine in the direction of the electrical apparatus 2 via the hydrodynamic torque converter 4. The output speed of the hydrodynamic torque converter 4 or the rotational speed of the turbine wheel 11 should be adjusted within a narrow operational rotational speed range in order to meet the requirements of the electrical system or the electrical apparatus 2. Since the input speed of the aircraft engine 1 varies in the high-pressure area, the rotational speed of the turbine wheel 12 should be adjusted by adjusting the guide blades 10 to the required value. The required input signals are provided for the adjustment mechanism 14 by a control system of the aircraft engine 1 in order to modify the current position of the guide blades 10 accordingly, as a function of the change in the input speed of the driveshaft of the aircraft engine 1.

(11) Accordingly, the characteristics of the hydrodynamic torque converter 4 are designed in order to be able to operate the electrical apparatus with a high degree of efficiency over the entire rotational speed range of the aircraft engine 1. The operative connection between the shaft 5 and the impeller 9 in the area of the coupling mechanism 12 or in the area of the freewheel 13 is detached while operating the electrical apparatus 2 as a generator, whereby the impeller 9 and the shaft 5 rotate independently of one another.

(12) In starting mode, torque is conducted in the direction of the driveshaft of the aircraft engine 1 by the electrical apparatus 2 in order to accelerate the driveshaft of the high-pressure area of the aircraft engine 1 to the starting rotational speed required for the starting sequence of the aircraft engine 1. When the electrical apparatus 2 is in this operational condition, the freewheel 13 connects the shaft 5 torque-proof to the impeller 9, whereby the hydrodynamic torque converter 4 is bypassed. When the aircraft engine 1 is in the engaged position, the hydrodynamic torque converter 4 is supplied with hydraulic fluid and, in turn, the impeller 9 is accelerated by the driveshaft of the aircraft engine 1, whereby the freewheel 13 is disengaged.

(13) The hydrodynamic torque converter 4 can either be integrated into an accessory generator 22 of the aircraft engine 1, with a drive train providing torque, and supplied via the oil system of the aircraft engine 1, or can be arranged in the area of the electrical apparatus 2, in which, in solutions known in the field, the so-called constant speed drive (CSD) is typically arranged. With the latter arrangement of the hydrodynamic torque converter 4, this can be provided via the oil system of the electrical apparatus 2. The connection to one of the oil systems is required in order to supply hydraulic fluid or oil, which is the medium for the transfer of the torque. Depending on the oil system selected, the oil is cooled via the respective cooler of the system involved.

(14) As depicted in the drawing, the electrical apparatus 2 is only attached to a supporting structure 16 of the aircraft engine 1 in the area of the section facing the hydrodynamic torque converter 4, whereby a resulting overhung moment always has an effect on the section of the electrical apparatus 2 attached to the supporting structure 16, depending on the component weight of the electrical apparatus 2. The high rotational speeds of the electrical apparatus 2 provide the option of designing or creating the hydrodynamic torque converter 4 with small component dimensions for a resulting defined torque. The equation describing the torque transmission capability of the hydrodynamic torque converter 4 shows that the rotational speed has a significant impact on the diameter of a hydrodynamic torque converter and hence on the overall dimensions and the overall weight of the unit featuring the electrical apparatus 2, the hydrodynamic torque converter 4 and the transmission 3. Hence, the overall weight of the unit, the overhung moment affecting the area of the supporting structure 16 and the attachment section of the supporting structure 16 on the transmission 3, the load in the area of the housing 17 of the accessory generator gearbox 3, and the bearing loads are low.

(15) As a result of the hydrodynamic torque converter being able to be integrated into the accessory generator with a drive train providing torque, it is also possible to minimize the overhung moment and the weight of the electrical apparatus 2 of the hydrodynamic torque converter 4 and of the transmission 3 as much as possible. In addition, the torque characteristics of the hydrodynamic torque converter 4 can be adjusted so that these are optimally adapted to defined variants and rotational speed ranges of the aircraft engine 1 in order to guarantee low levels of power loss and minimal heat generation.

(16) In turn, in comparison with the aircraft engines designed with constant speed drives known to date, the reduced number of components owing to the use of the hydrodynamic torque converter 4 provides a straightforward option of improving the reliability of the entire unit. In addition, unlike for aircraft engines, which are designed with conventional constant speed drives, for the aircraft engine 1 described above, certain rotational speed ranges of the aircraft engine 1 need not be avoided.

LIST OF REFERENCE NUMERALS

(17) 1 Aircraft engine 2 Electrical apparatus 3 Transmission 4 Hydrodynamic torque converter 5 Shaft of the electrical apparatus 6 to 8 Spur gear 9 Impeller of the hydrodynamic torque converter 10 Adjustable guide blades of the hydrodynamic torque converter 11 Turbine wheel of the hydrodynamic torque converter 12 Coupling mechanism 13 Switch element 14 Adjustment mechanism 15 Wiring 16 Supporting structure 17 Transmission housing 18 Rotor of the electrical apparatus 19 Stator of the electrical apparatus