Dual-purpose integrated gear for hybrid drive applications

Abstract

A hybrid powertrain is disclosed. The hybrid powertrain includes at least one gas turbine that drives a load and an electric machine unit that is also connected to the load. A clutch is mounted between the gas turbine and the load. Further, an integrated reduction gear unit is disposed between the load and the motor unit to accommodate different operating speeds.

Description

[0001] manual Technical Field

[0002] The present disclosure relates to a dual-purpose integrated gear for hybrid powertrain applications of a hybrid configuration powertrain system, which is provided with an electric motor / generator and an integrated reduction gear unit with a compressor axis. Background Art

[0003] Gas turbines are often used to provide torque to loads such as compressors, for example in the liquefied natural gas sector and in the oil and gas industry in general. Gas turbines are typically connected to a load such as a compressor, pump or any rotating equipment as mentioned, via a rotating shaft or a rotating transmission assembly.

[0004] More specifically, with reference to liquefied natural gas (LNG) processing, LNG is liquefied through a liquefaction process in which natural gas is cooled using a refrigeration cycle so that the natural gas becomes a liquid for storage and transportation.

[0005] To cool the LNG, a refrigerant is cooled by a compressor, then condensed and expanded to remove heat from the natural gas flowing into a heat exchanger. The compressor is usually driven by a gas turbine.

[0006] In recent years, electric machines have also been included in the above arrangement. Configurations in which there is a gas turbine, a load and an electric machine along the axis are generally known and are referred to as hybrid powertrain configurations, hybrid powertrains, hybrid turbine compressor powertrains or simply hybrid powertrains. In such configurations, the electric machine can operate as an electric motor, such as an auxiliary, for example to alternately provide torque to a load (e.g., a compressor) when the gas turbine is not operational, or to provide torque directly to the gas turbine, for example during a start-up phase.

[0007] A known configuration includes a gas (or steam) turbine connected in series, a load such as a compressor connected to the gas turbine through a transmission assembly. Specifically, the transmission assembly includes a first transmission shaft having one end connected to the gas turbine, a second transmission shaft having one end connected to the load, and a clutch connecting the first transmission shaft and the second transmission shaft. The clutch is operated to mechanically decouple or couple the two transmission shafts to transfer the power generated by the gas turbine to the load. The hybrid powertrain also includes an electric machine connected to the load.

[0008] The electric machine can also be operated as a generator, for example when the power generated by the gas turbine exceeds the power normally required by the load. In this case, the power is converted into electrical energy by the electric machine and then injected into the public grid, for example.

[0009] Gas turbines and electric machines typically have different operating speeds, so transmission torque issues arise when designing a hybrid powertrain. Specifically, the electric machine can be selected in the reference solution to operate at 1500RPM or 1800RPM (in the case of a 4-pole machine) or 3000RPM / 3600RPM (in the case of a 2-pole machine). This enhances supplier availability and potential commonality with pure power generation applications.

[0010] Typically, the operating speed range of the electric motor is lower than the operating speed range of the gas turbine. This is a hybrid powertrain design problem, adapting the speed of the electric motor to the speed of the gas turbine. In prior art hybrid powertrains, the electric motor typically has to be overdesigned. However, this means higher cost, weight and increased footprint. In addition, there is a coupling problem between the electric motor and the load, where bidirectional torque transfer at variable speed is required to allow torque to be transferred to drive the load when the electric motor operates as a motor, or to be driven by the load when the electric motor operates as a generator.

[0011] This implies rotor dynamic limitations and design barriers to the mechanical coupling between the load and the electric machine. Therefore, an improved torque transfer connection for the electric machine is welcomed in the art. More generally, it is desirable to provide a torque transfer arrangement that allows torque compatible transfer between the electric machine (at lower speeds) and a load that is directly connected to the gas turbine, the torque transfer arrangement operating at higher speeds, especially when the electric machine is operating as a motor, i.e., transferring torque to the load. Summary of the invention

[0012] In one aspect, the subject matter disclosed herein is directed to a hybrid powertrain having a load driven by torque, such as a compressor or a pump, and a gas turbine for generating a driving torque to drive the load. The gas turbine operates at a first speed belonging to a first operating speed range. The gas turbine is also operably connected to the load. The hybrid powertrain also includes a motor unit and a rotating shaft, the motor unit being mechanically connected to the load, the rotating shaft mechanically connecting the load and the motor unit. The motor unit is capable of operating at a second speed belonging to a second operating speed range, wherein the second speed is lower than the first speed of the gas turbine. In addition, the hybrid powertrain includes an integrated reduction gear unit, such as a revolving type reduction gear unit, which is connected to the motor unit and to the rotating shaft. The integrated reduction gear unit is capable of transmitting torque from the motor unit to the load, and vice versa. In addition, the integrated reduction gear unit is suitable for matching the first speed of the gas turbine with the second speed of the motor unit.

[0013] In another aspect of the subject matter disclosed herein, an integrated reduction gear unit includes: a center sun gear having a high-speed flange capable of being mechanically connected to a rotating shaft; an inner ring gear having internal teeth; a group of star wheels arranged in the inner ring gear and meshing with the internal teeth of the inner ring gear; a low-speed flange mechanically connected to the inner ring gear and mechanically connected to the motor unit; and a joint connecting the center sun gear and the rotating shaft for torque transmission.

[0014] Another aspect of the invention resides in the fact that the hybrid powertrain comprises a mechanical oil pump which is mechanically connected to the integrated reduction gear unit for operation of the integrated reduction gear unit. The mechanical oil pump comprises an upper coupling flange and a lower coupling flange for coupling the mechanical oil pump to the integrated reduction gear unit.

[0015] In another aspect of the subject matter disclosed herein, a hybrid powertrain system includes a torque limiter device coupled to a low-speed flange, the torque limiter device being capable of separating the motor unit from the rotating shaft in the event of an excessive torque transmitted through the rotating shaft. The torque limiter device may include: a shear bolt coupled to a support bearing; a collar, the collar surrounding the shear bolt coupled to the support bearing, wherein the collar is arranged to match the low-speed flange; and one or more shear pins, each having a shear neck and arranged to connect the collar and the low-speed flange, wherein the shear pin is adapted to break in the event that the torque transmitted through the rotating shaft exceeds a preset threshold. In another embodiment, the low-speed flange may have a flat surface. The collar may have a flat surface that is recessed to match the flat surface of the low-speed flange. The collar may have one or more seats that are obtained on the flat surface. In addition, the torque limiter device includes one or more axial springs, each axial spring being accommodated in a corresponding seat, wherein the axial spring is capable of separating the collar and the low-speed flange in the event of a shear pin breaking.

[0016] In another aspect of the subject matter disclosed herein, the motor unit is configured to operate as an electric motor to deliver torque to a load and to operate as a generator to receive torque from the load. The motor unit is connected to a power grid such that when the motor unit is operable as an electric motor, the power grid supplies power to the motor unit, and when the motor unit is operable as a generator, the motor unit injects power into the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete appreciation thereof will be readily obtained as the disclosed embodiments of the present invention and many of its attendant advantages become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0018] Figure 1 shows a schematic diagram of a hybrid powertrain system according to a first embodiment;

[0019] Figure 2 A rotary type integrated reduction gear unit is shown;

[0020] Figure 3 shows an embodiment of coupling a motor unit to a rotating shaft of a hybrid powertrain according to a second embodiment;

[0021] Figure 4 The section taken along the section line AA is shown. Figure 3 cross-section; and

[0022] Figure 5 Shown integrated in Figure 3 A torque limiter device in a hybrid powertrain system. DETAILED DESCRIPTION

[0023] Gas turbines are used to drive a load connected to a shaft, such as a compressor or the like. Recently, so-called hybrid drivetrains are being marketed, which also integrate electric motors. Gas turbines and electric motors are generally not compatible, since they run at different speeds.

[0024] In order to avoid designing an overly bulky electric machine, according to one aspect, the present subject matter is directed to the integration of an integrated reduction gear unit capable of adapting the operating speed range of the gas turbine to that of the electric machine in a bidirectional manner while transmitting torque.

[0025] Now referring to the accompanying drawings, Figure 1 A hybrid powertrain 1 according to a first embodiment is shown. The hybrid powertrain 1 comprises a gas turbine 2 and a load 3 driven by the gas turbine 2. The gas turbine 2 is operated at a first speed which may typically be in the range of 65% to 105% of the nominal speed.

[0026] The gas turbine 2 comprises a gas compressor 21 capable of compressing air taken from the environment, which is delivered to a burner 22. In the burner 22, fuel is added to the gas flow, and a fuel / air mixture is formed and ignited. The combustion gases produced in the burner are delivered to a high-pressure turbine 23 and partially expanded therein, thereby generating mechanical power. The mechanical power generated by the high-pressure turbine 23 is used to drive the gas generator compressor 21.

[0027] The load 3 is connected to the gas turbine through a transmission assembly 4. Specifically, the transmission assembly 4 includes a first transmission shaft 41 having one end connected to the gas turbine 2, a second transmission shaft 42 having one end connected to the load 3, and a clutch 43.

[0028] In the illustrated layout of the hybrid powertrain 1, the clutch 43 includes clutch plates, namely a first clutch plate 431 connected to the first transmission shaft 41 and a second clutch plate 432 connected to the second transmission shaft 42. The clutch plates 431 and 432 are capable of engaging the power transmission. The clutch 43 is accommodated in an accommodation housing 44.

[0029] The hybrid powertrain 1 further comprises a motor unit 6 mechanically connected to the load 3 via the rotating shaft 5. The motor unit 6 may operate as an electric motor, thereby providing torque to the load 3, or as a generator, thereby converting torque received via the rotating shaft 5 into electricity.

[0030] In the embodiment shown, the load 3 is a compressor, however, in other embodiments, the load may be a different load, such as a pump or the like.

[0031] The hybrid powertrain 1 further includes an integrated reduction gear unit 7 connected to the rotating shaft 5 and the motor unit 6 .

[0032] The integrated reduction gear unit 7 is adapted to adjust the operating speed range of the motor unit 6, which can operate in a second operating speed range that is lower than the operating speed of the gas turbine 2. Typically, the motor unit 6 can operate at 1.500 rpm to 1.800 rpm (in the case of a 4-pole motor) or 3.000 rpm to 3.600 rpm (in the case of a 2-pole motor).

[0033] The integrated reduction gear unit 7 can operate bidirectionally, i.e., it can reduce or increase the speed between the points to which it is connected, as better explained below. In particular, when the motor unit 6 operates as an electric motor, i.e., as described above, to provide torque to the load 3, the integrated reduction gear unit 7 increases the speed on the rotating shaft 5 for driving the load unit 6. In other words, the integrated reduction gear unit increases the rotation speed taken from the second operating speed range to the speed of the first operating speed range, so that the rotating shaft 5 can transmit a torque suitable for driving the load 3. On the contrary, when the motor unit 6 operates as a generator, the motor unit converts the torque generated by the gas turbine 2 received through the rotating shaft 5 into electrical energy, which can be injected into the grid G, for example, or can be used to charge the battery pack, or for driving other loads. In this case, the integrated reduction gear unit 7 reduces the speed belonging to the first operating speed range to the speed belonging to the second operating speed range, wherein, as described above, the second speed is lower than the first speed.

[0034] In the embodiment in question, the rotation of the rotating shaft 5 is always in the same direction, which may be clockwise or counterclockwise, the motor unit 6 operating as a motor or a generator.

[0035] The relationship between torque and speed is

[0036]

[0037] Wherein T is the torque vector, v is the speed, and P is the power. Therefore, the integrated reduction gear unit 7 operates as a speed converter or speed adapter.

[0038] exist Figure 2 , an example of an integrated reduction gear unit 7 is shown, which is an epicyclic type gear, comprising a central sun wheel 71 having a high-speed flange 72, which can be connected to a high-speed source, i.e., in this case, to a load unit 6 via a rotating shaft 5. As mentioned above, the load unit 6 mainly runs at the speed of the gas turbine 2, which is higher than the speed of the motor unit 6.

[0039] The integrated reduction gear unit 7 also comprises an inner ring gear 73, also called a ring, with internal teeth (not shown in the figure). The inner ring gear 73 rotates according to the arrow R during operation. A set of star wheels, collectively denoted by the reference numeral 74, is arranged inside the inner ring gear 73 and is mechanically connected to a low-speed flange 75 for connection to the motor unit 6. The set of star wheels 74 meshes with the internal teeth of the inner ring gear 73.

[0040] The orbital integrated reduction gear unit 7 is bidirectional, ie, it can transmit and convert torque and speed in both directions, thereby allowing the motor unit 6 to operate as a motor as well as a generator in the second speed range.

[0041] In other embodiments, other types of integrated reduction gear units 7 may be used.

[0042] Due to the limited space available within conventional customer plants, there is often a requirement to minimize the drivetrain footprint and impact on auxiliary equipment. When the initial turbo compressor equipment is driven by a high-speed gas turbine 2, this will mean selecting a high-speed variable speed drive system (VSDS) (limited range of available suppliers, also given active front-end variable frequency drives (VFDs)). At the same time, conventional gearing will result in a larger drivetrain footprint.

[0043] refer to Figure 3 and Figure 4 , shows another embodiment of coupling the motor unit 7 to the rotating shaft 5 by adjusting the rotation speed. Specifically, the epicycloid cantilever integrated reduction gear unit 7 is shown.

[0044] In this case, the speed reduction of VSDS is achieved by epicycloidal gears, cantilever or pedestal type on the motor (which is the VSDS active front end type), and the epicycloidal gears should be designed to withstand bidirectional torque and variable speed operation.

[0045] Specifically, continue to refer to Figure 3 , shows that the motor unit 6 comprises a motor 61, which can be operated as an electric motor or a generator, as described above, and a cooler 62, which is arranged above the motor 61 to extract heat during its operation. The motor 61 also comprises an electrical connection generally indicated by the reference numeral 611, and a coupling flange 612 with an associated coupling crown 613, whereby the motor 61 is connected to the integrated reduction gear unit 7, which in the embodiment shown is of the epicyclic type, but can also be of any other type. The coupling crown 613 is mechanically connected to the low-speed flange 75 of the integrated reduction gear unit 7.

[0046] Finally, still refer to Figure 3 , the integrated reduction gear unit 7 also includes a joint 76, which connects the central sun gear 71 and the rotating shaft 5 for torque transmission. The joint includes a main body 761 and a connecting flange 762, the latter being connected to the main body. The connecting flange 762 has a plurality of holes 763 for connection by a plurality of bolts. In addition, an inspection cover 764 can be seen to allow inspection inside the main body in the event of a malfunction or torque transmission problem.

[0047] In the embodiment shown, a mechanical oil pump 8 is also installed, which is mechanically connected to the integrated reduction gear unit 7. Specifically, a wheel of the integrated reduction gear unit 7 is used to operate the mechanical oil pump 8. The mechanical oil pump 8 includes an upper coupling flange 81 and a lower coupling flange 82 for coupling the mechanical oil pump 8 to the integrated reduction gear unit 7.

[0048] In one embodiment, the mechanical pump 8 can be driven by a kinematic chain (not shown in the figure), which includes, for example, an auxiliary shaft connected to the pump 8, a gear keyed to the auxiliary shaft, and one or more transmission devices, such as gears, etc., thereby connecting the gear and the auxiliary shaft to the low-speed flange 75, or generally to the rotating part of the integrated reduction gear unit 7.

[0049] Typically, mechanical oil pumps are provided in hybrid powertrains, however, they are not integrated into the system itself but are merely arranged close to the system, thereby increasing the overall footprint of the device. It is apparent that the integration of the mechanical oil pump 8 allows the size of the hybrid powertrain 1 to be limited.

[0050] As described above, the epicycloidal gear not only allows the installation of a mechanical oil pump, providing benefits in reducing the lubrication oil console footprint, but also allows the installation of a torque limiter device (TLD) to limit excessive torque from the motor, providing benefits to axis design (e.g., couplings).

[0051] Specifically, now refer to Figure 4 , showing a partial longitudinal section of the high-speed flange 72. Now referring to Figure 5 , the torque limiter device 9 is coupled to the low speed flange 75. In particular, it can be seen that the torque limiter device 9 includes a shear bolt coupling support bearing 91, which has a centering bolt 92 for centering the position of the torque limiter device 9 and the low speed flange 75. The torque limiter device 9 also includes a collar 92, which surrounds the shear bolt coupling support bearing 91. The collar 92 has a flat surface 93, which is used to match with a corresponding flat surface 751 of the low speed flange 75. One or more shear pins 94 are arranged to pass through the collar 92 and the low speed flange 75. Each of the shear pins 94 has an associated shear neck 941. The shear pins 94 connect the collar 92 and the low speed flange 75. Specifically, the shear pins 94 keep the flat surface 93 of the collar and the flat surface 751 of the low speed flange 75 matched. Finally, the collar 92 has one or more seats 931 obtained on the flat surface 93, and the torque limiter device 9 comprises a set of axial springs 95, each axial spring being arranged to be preloaded in the relative seat 921. The axial springs 95 are able to separate in the same case of shear pin 94 breaking.

[0052] In other embodiments, other types of torque limiter devices may be installed, such as a torque clock type or the like.

[0053] The above-described hybrid powertrain system 1 operates as follows.

[0054] When the gas turbine 2 is running, torque can be transmitted to the load 3, which in the case under discussion is the compressor as described above, through the clutch 43. The two clutch plates 431 and 432 of the clutch 43 can be separated, so that no torque is transmitted to the load 3. When the clutch plates 521 and 522 are connected, the torque generated by the gas turbine 2 can be transmitted from the gas turbine 2 to the load 3.

[0055] In the case of excess torque, the motor unit 6 operates as a generator. Therefore, the rotating shaft 5 can transmit the excess torque to the motor unit 6 to convert it into electrical energy, for example, to be injected into the grid G.

[0056] The rotating shaft 5 rotates at a speed belonging to the first operating speed range, i.e., at the operating speed of the gas turbine 2, which is usually about 10.000 rpm or higher. As mentioned above, this rotation speed is much higher than the operating speed of the conventional motor unit 6, which usually rotates at an operating speed of 1.500 rpm to 3.600 rpm.

[0057] The integrated reduction gear unit 7, which receives torque from the rotating shaft 5 via the high-speed flange 72, reduces the speed of the rotating shaft 5, i.e., the speed belonging to the first operating range, by means of the internal ring gear 73 and the star wheel 74. Then, the speed is reduced from the (higher) operating speed of the gas turbine 2 to the (lower) operating speed of the motor unit 6, i.e., the speed of the second operating speed range, so as to drive the same motor unit 6 via the low-speed flange 75. At the same time, the gears of the integrated reduction gear unit 7 operate the oil pump 8, which pumps oil and lubricant into the entire hybrid powertrain 1.

[0058] The integrated reduction gear unit 7 is a passive device and may be affected by torque pulsation or similar faults. In this case, the torque limiter device 9 protects the hybrid powertrain 1. In fact, in normal operation, the shear pins 94 of the torque limiter device 9 are subjected to shear forces. When the transmitted torque causes a force that exceeds the shear strength of the pin, that is, exceeds a specific shear strength that can be preset by appropriate design, the shear pins 94 break along the shear neck 941 of each shear pin 94, thereby mechanically decoupling the motor unit 6 from the rotating shaft 5, and thus decoupling the load 3 through the gas turbine 2.

[0059] Furthermore, the axial spring 95 releases the potential energy stored therein, performing safe separation of the low speed flange 75 from the shear bolt coupling support bearing 91 of the torque limiter device 9 , and thus from the rotating shaft 5 .

[0060] In a symmetrical manner, in the case where the motor unit 6 operates as an electric motor in order to drive the compressor 3, for example as an auxiliary, the (lower) operating speed generated by the motor unit 6 for transmitting power (and therefore torque) to the load 3 is increased by the integrated reduction gear unit 7, which then operates in a bidirectional manner. The motor unit 6 draws its power from the grid G.

[0061] Also in this case, in the event of a torque peak or any other problem on the rotating shaft 5 , the torque limiter device 9 decouples the electric machine unit 6 from the rotating shaft 5 and thus via the gas turbine 2 and the load 3 .

[0062] Advantages of the present disclosure relate to an enhanced VSDS supplier reach, with clear commercial benefits.

[0063] Another advantage of the present disclosure is that the integration of the gear can be used for pure power generation or hybrid applications in terms of design. In addition, the integrated gear can be equipped with a torque limiter device to limit excessive torque from the motor, thereby achieving rotor dynamic benefits on the motor and compressor design.

[0064] Although various aspects of the present invention have been described in terms of various specific embodiments, it will be apparent to those skilled in the art that various modifications, variations, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless otherwise indicated herein, the order or sequence of any process or method steps may be changed or reordered according to alternative embodiments.

[0065] Reference has been made in detail to embodiments of the present disclosure, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of explanation of the present disclosure, rather than by way of limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or substance of the present disclosure. References to "one embodiment" or "embodiment" or "some embodiments" throughout this specification are intended to mean that the particular features, structures or characteristics described in conjunction with the embodiments are included in at least one embodiment of the disclosed subject matter. Therefore, the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" that appear in multiple places throughout the specification do not necessarily refer to the same embodiment. In addition, in one or more embodiments, particular features, structures or characteristics may be combined in any suitable manner.

[0066] When introducing elements of various embodiments, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

1. A hybrid powertrain system (1), the hybrid powertrain system comprising: A load (3), the load being driven by a torque; a gas turbine (2) for generating a driving torque for driving the load (3), wherein the gas turbine (2) operates at a first speed belonging to a first operating speed range, and wherein the gas turbine (2) is operatively connected to the load (3); a motor unit (6) mechanically connected to the load (3); and A rotating shaft (5) mechanically connecting the load (3) and the motor unit (6); Characteristics of the hybrid powertrain The motor unit (6) is capable of operating at a second speed belonging to a second operating speed range, wherein the second speed is lower than the first speed of the gas turbine (2); and The hybrid powertrain (1) further comprises an integrated reduction gear unit (7), the integrated reduction gear unit being connected to the motor unit (6) and the rotating shaft (5), wherein the integrated reduction gear unit (7) is capable of transmitting the torque from the motor unit (6) to the load (3) and vice versa, and The integrated reduction gear unit (7) is adapted to match the first rotational speed of the gas turbine (2) and the second rotational speed of the motor unit (6).

2. The hybrid powertrain (1) according to the preceding claim, wherein the integrated reduction gear unit (7) is of the epicyclic type.

3. The hybrid powertrain (1) according to the preceding claim, wherein the integrated reduction gear unit (7) comprises: a central sun gear (71) having a high-speed flange (72) capable of mechanically connecting to the rotating shaft (5); an inner gear ring (73), the inner gear ring having inner teeth, a set of star wheels (74), which are arranged in the inner gear ring (73) and mesh with the inner teeth of the inner gear ring (73), a low speed flange (75) mechanically connected to the inner gear ring (73) and mechanically connected to the motor unit (6), and A joint (76) connects the central sun gear (71) and the rotating shaft (5) for torque transmission.

4. The hybrid powertrain (1) according to any one of claims 2 and 3, comprising a mechanical oil pump (8) mechanically connected to the integrated reduction gear unit (7) to operate the integrated reduction gear unit, The mechanical oil pump (8) comprises an upper coupling flange (81) and a lower coupling flange (82) for coupling the mechanical oil pump (8) to the integrated reduction gear unit (7).

5. A hybrid powertrain (1) according to any one of claims 3 or 4, comprising a torque limiter device (9), which is coupled to the low-speed flange (75) and is capable of separating the motor unit (6) from the rotating shaft (5) in the event of excessive torque being transmitted through the rotating shaft (5).

6. A hybrid powertrain (1) according to the preceding claim, wherein the torque limiter device (9) comprises The shear bolt couples the support bearing (91), a collar (92) surrounding the shear bolt coupling support bearing (91), wherein the collar (92) is arranged to mate with the low speed flange (75), and One or more shear pins (94), each having a shear neck (941) and arranged to connect the collar (92) and the low speed flange (75), wherein the shear pins (94) are adapted to break when the torque transmitted through the rotating shaft exceeds a preset threshold.

7. A hybrid powertrain (1) according to the preceding claim, wherein the low speed flange (75) has a flat surface (751), wherein the collar (92) has a flat surface (93) that is recessed to match the flat surface (751) of the low speed flange (75), wherein said collar (92) has one or more seats (931) obtained on said flat surface (93), and The torque limiter device (9) comprises one or more axial springs (95), each axial spring being accommodated in a corresponding seat (931), wherein the axial springs (95) are capable of separating the collar (92) and the low-speed flange (75) in the event of breaking of the shear pin (94).

8. A hybrid powertrain (1) according to any one of the preceding claims, wherein the first operating speed range of the gas turbine (2) is comprised between 3.000 rpm and 12.000 rpm; and The second operating speed range of the motor unit (6) is comprised between 1.500 rpm and 1.800 rpm, or between 3.000 rpm and 3.600 rpm.

9. A hybrid powertrain (1) according to any one of the preceding claims, comprising a transmission assembly (4) connecting the load (3) and the gas turbine (2), The transmission assembly (4) comprises a first transmission shaft (41), the first transmission shaft having one end connected to the gas turbine (2), a second transmission shaft (42) having one end connected to the load (3), and A clutch (43) having a first clutch plate (431) connected to the first transmission shaft (41) and a second clutch plate (432) connected to the second transmission shaft (42), wherein the first clutch plate (431) and the second clutch plate (432) are capable of engaging a power transmission.

10. A hybrid powertrain (1) according to any one of the preceding claims, wherein the electric machine unit (6) is configured to operate as an electric motor to deliver torque to the load (3) and as a generator to receive torque from the load (3).

11. A hybrid powertrain (1) according to the preceding claim, wherein the motor unit (6) is connected to a grid (G), wherein when the motor unit (6) operates as an electric motor, the grid (G) supplies power to the motor unit (6), and when the motor unit (6) operates as a generator, the motor unit (6) injects power into the grid (G).

12. A hybrid powertrain (1) according to any one of the preceding claims, wherein the load (3) is a compressor or a pump.

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