Improved clutch case for hybrid transmission applications

Abstract

A hybrid powertrain is disclosed. The hybrid powertrain includes at least one gas turbine and a clutch box. The clutch box comprises a torque limiting device which is arranged in a containing housing of the clutch box itself. The torque limiting device mechanically decouples the clutch from the gas turbine if the torque transmitted to the clutch exceeds a threshold value. A clutch box is also disclosed.

Description

[0001] manual Technical Field

[0002] The present disclosure relates to an improved clutch box system for hybrid powertrain applications. Background Art

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

[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] 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 injected into the public grid, for example.

[0008] Gas turbines and electric machines typically have different operating speeds and inertias, so transferring torque can be a problem when designing a hybrid powertrain.

[0009] Faced with such technical design problems, the first solution was the overdesign of the shaft connecting the different parts of the hybrid powertrain, namely the gas turbine, the load and the electric motor. However, this design approach has proven to be expensive. In addition, between the gas turbine and the electric machine, as well as between the electric machine and the load, a remotely controllable clutch is usually installed. The clutch allows the decoupling of the different mechanical components of the hybrid powertrain configuration. Typically, the hybrid powertrain includes a clutch to facilitate the transmission of power from the gas turbine (or from the electric machine) to the load. The clutch allows an easier transmission of torque through the shaft.

[0010] Finally, as a matter of good design practice, the hybrid powertrain includes a torque limiting device (TLD) installed upstream of each coupling (i.e., clutch). A TLD is an automatic device whose purpose is to protect mechanical components from possible damage in the event of a mechanical overload. More specifically, a TLD can limit torque in several ways. In a first example, the TLD can limit torque by slipping, as in the case of a friction plate slip clutch, or by decoupling the load, as in the case of a shear pin type TLD. In the latter case, a mechanical component (i.e., a shear pin) is sacrificed to disconnect the moving and overloaded shaft.

[0011] The TLD installed in the coupling requires a suitable landing gear, capable of shutting down the unit safely in case of TLD intervention. Such a coupling with TLD and landing gear results in a significantly heavier than normal coupling, resulting in rotordynamic effects on the driver and driven equipment / machine. Therefore, the coupling (without TLD) can be selected according to normal practice.

[0012] Due to the heavy couplings, this means severe rotor dynamic restrictions on the compressor design and drive train operating range. In addition, a feasibility study is required to evaluate the torque rating of each drive train axis or motor to ensure correct operation of the system. In addition, there are TLD interventions that are more difficult to detect.

[0013] Therefore, improvements in torque transfer through clutches are welcome in the art.More generally, it is desirable to provide a torque transfer arrangement that allows for a reduction in the complexity and overall cost of a hybrid powertrain. Summary of the invention

[0014] 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 pump, and a gas turbine for generating drive torque. The hybrid powertrain also includes a main transmission assembly equipped with a clutch box. The clutch box has a housing and a clutch. The first transmission shaft has one end mechanically connected to the gas turbine and the other end mechanically connected to the clutch box. The second transmission shaft has one end mechanically connected to the clutch box. The clutch box includes a torque limiting device, which is arranged in the housing, and the torque limiting device is connected between the clutch and the first transmission shaft and / or the second transmission shaft, so that when the torque transmitted to the clutch exceeds a threshold value, the torque limiting device mechanically decouples the clutch from the first transmission shaft and / or the second transmission shaft.

[0015] In another aspect, the subject matter disclosed herein relates to a torque limiting device having: a body; a collar rotatably connected to a first transmission shaft; a sprocket rotatably connected to a clutch and arranged to face the collar; and a shear pin connecting the collar and the sprocket. When torque is transmitted from the collar to the sprocket, the shear pin is subjected to shear force. In the event that the transmitted torque causes a force exceeding a shear strength threshold of the shear pin, the shear pin breaks to mechanically decouple the gas turbine.

[0016] Another aspect of the disclosure resides in the fact that the clutch comprises a first clutch plate connected to the first transmission shaft and a second clutch plate connected to the second transmission shaft. The second transmission shaft is connectable to a load.

[0017] In another aspect, the subject matter disclosed herein is directed to a hybrid powertrain system including an electric machine and another transmission assembly that mechanically connects the electric machine and a load. The electric machine can operate as an electric motor and as a generator.

[0018] In another aspect, the subject matter disclosed herein relates to a hybrid powertrain system including an electric motor. A second drive shaft is connected to the electric motor. In addition, the hybrid powertrain system includes another transmission assembly having an additional clutch box and a first drive shaft and a second drive shaft, the first drive shaft having one end mechanically connected to the electric motor and another end mechanically connected to the clutch box, the second drive shaft having one end mechanically connected to the electric motor and another end mechanically connected to the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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:

[0020] Figure 1 shows a schematic diagram of a hybrid powertrain system according to a first embodiment;

[0021] Figure 2 shows a longitudinal section of a clutch box according to a first embodiment;

[0022] Figure 3 shows a second longitudinal section of the clutch box according to the first embodiment; and

[0023] Figure 4 A schematic diagram of a hybrid powertrain system according to a second embodiment is shown. DETAILED DESCRIPTION

[0024] The gas turbine is used to drive a load connected to the shaft, such as a compressor, etc. Recently, so-called hybrid powertrains are being marketed, which also integrate electric machines. The torque transmission of the hybrid powertrain is connected by a clutch to allow smooth torque transmission between components with different operating speeds.

[0025] According to one aspect, the subject matter relates to a clutch box with integrated torque limiting devices, so that they can have both a protection function, allowing safe shutdown of the unit in case of intervention, and a stabilizer function, since they are mounted in a specific position, instead of the usual stabilizing weights of the clutch. Thus, the TLD inside the clutch box (which requires additional mass to stabilize the shaft between the bearings) does not lead to rotordynamic disadvantages.

[0026] Now referring to the accompanying drawings, Figure 1 A hybrid powertrain 1 according to a first embodiment is shown. The hybrid powertrain 1 includes a gas turbine 2 and a load 3 driven by the gas turbine 2 .

[0027] 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.

[0028] The load 3 is connected to the gas turbine through a transmission assembly 4. Specifically, the main 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 box 5. In the illustrated layout of the hybrid powertrain 1, the clutch box 5 is connected to the first transmission shaft 41 and to the second transmission shaft 42.

[0029] In the clutch box 5, two clutch plates 521 and 522 are schematically shown, which are mechanically connected to the other end of the main transmission shaft 41 and the other end of the second transmission shaft 42, respectively. The clutch plates 521 and 522 can engage the power transmission device. The two clutch plates 521 and 522 are accommodated in the accommodating housing 51.

[0030] The hybrid powertrain 1 further comprises an electric machine 6 which is mechanically connected to the load 3 via a shaft 7, which in the case in question comprises only the second shaft. The electric machine 6 can operate as an electric motor, thereby providing torque to the load 3, or as a generator, thereby converting torque received via the shaft 7.

[0031] In the embodiment shown, the load is a compressor, however, in other embodiments the load may be a different load, such as a pump or the like.

[0032] Reference now Figure 2 and Figure 3 , shows a longitudinal section of a clutch box 5, which is shown in more detail. In particular, it can be seen that the clutch box 5 includes a support structure 53 to support the entire clutch box 5 itself, as well as the weight of the first transmission shaft 41 and the second transmission shaft 42 connected to the clutch box 5. The clutch box 5 also includes a clutch 52, which, as mentioned above, includes two clutch plates 521 and 522 connected to the first transmission shaft 41 and to the second transmission shaft 42, respectively. The clutch 52 has the function of decoupling the power transmission between the first transmission shaft 41 and the second transmission shaft 42, so as to mechanically disconnect the gas turbine 2 from the clutch 52.

[0033] The clutch box 5 also includes a plurality of combined thrust bearings 54, which are arranged in the containing housing 51. Specifically, in the embodiment discussed, there are four combined thrust bearings 54. Combined thrust bearings 541 and 542 are fixed to the support structure 53 and connected to the first transmission shaft 41; the other two combined thrust bearings 543 and 544 are fixed to the support structure 53 and connected to the second transmission shaft 42.

[0034] The clutch box 5 also includes a torque limiting device 55 connected between the first transmission shaft 41 and the clutch plate 521 of the clutch 52. The torque limiting device 55 includes a main body 551, two journal bearings 552, each of which has an outer ring 5521 and an inner ring 5522 facing each other, and a plurality of balls 5523 rolling therebetween.

[0035] The body 551 has a collar 5511 connected to a journal bearing 552 so as to rotate therewith, and a sprocket 5512 is connected to the clutch plate 521. The collar 5511 and the sprocket 5512 face each other and are connected by one or more shear pins 553. In this way, the shear pin 553 connects the two rotating members, namely the collar 5511 and the sprocket 5512, and the shear pin is subjected to shear force when torque is transmitted. It can be seen that the torque limiting device 55 is completely accommodated in the clutch box 5.

[0036] The introduction of the torque limiter device 55 allows avoiding an overdesign of the shaft line, which could limit the operating range of the hybrid powertrain 1. In fact, the mass of the torque limiter device 55 stabilizes the main shaft assembly 4 between the combined thrust bearings 543 and 544, thereby preventing rotor dynamic disadvantages. The mass of the torque limiter device 55 replaces the usual mass applied to the shaft for its stabilization.

[0037] Specifically, in the clutch box 5, the radial bearings only support the weight of the rotor. These bearings are all hydrodynamic sleeve bearings with a single combined thrust surface, and they need to run under load to remain stable. Therefore, the bearing stiffness and damping coefficient are greatly affected by the load. The best practice to ensure that the bearing provides a minimum specific pressure is to add mass between the two bearings of each shaft in order to stabilize the specific pressure. In addition, high abnormal torque causes the shaft to have a larger minimum cross-sectional diameter than if the torque was limited by the torque limiting device 55. Therefore, the diameter of bearings 541, 542, 543 and 544 is directly related to the pick-up torque. The larger the diameter of the bearing, the lower the specific pressure of the bearing. Therefore, people are very interested in limiting the abnormal torque in order to ensure the stability of the bearing by sufficient loading.

[0038] In other embodiments, other types of torque limiting devices may be installed, such as torque clock types and the like.

[0039] The hybrid powertrain system 1 according to the first embodiment described above operates as follows.

[0040] When the gas turbine 2 is running, torque can be transmitted to the load 3, which is a compressor, through the clutch box 5. The two clutch plates 521 and 522 of the clutch can be separated, so that torque is not transmitted to the load 3. When the clutch plates 521 and 522 are connected, torque can be transmitted from the gas turbine 2 to the load 3, and the shear pin 553 is subjected to shear force. Then, the first transmission shaft 41 and the second transmission shaft 42 are rotated according to, for example, the rotation arrow R (see Figure 1 )Rotate.

[0041] When the transmitted torque causes a force which exceeds the shear strength of the pin, ie a certain shear strength which can be preset by suitable design, the shear pin 553 breaks and the gas turbine 2 and the load 3 are mechanically decoupled.

[0042] Reference now Figure 4 , shows a second embodiment of a hybrid powertrain 1 '. In this case, a different layout is shown, with two clutch boxes 5, as better explained below.

[0043] The hybrid powertrain 1' comprises a gas turbine 2 and an electric motor 6, which are connected by a first clutch box 5, similar to the clutch box of the first embodiment. Two clutch plates 521 and 522 of the clutch 52 are connected to the first transmission shaft 41 and to the second transmission shaft 42, respectively.

[0044] The load 3 is connected to the electric machine 6 via a transmission assembly 8 having a clutch box 5 similar to the clutch box of the first embodiment of the hybrid powertrain 1 described above.

[0045] Another transmission assembly 8 includes first and second transmission shafts 81 and 82, and a clutch box 52. Two clutch plates 521 and 522 of a clutch 52 of a second clutch box 5' provided in another transmission assembly 8 are connected to the first transmission shaft 81 and to the second transmission shaft 82, respectively.

[0046] In the hybrid powertrain 1 ′, the motor 6 can operate as an auxiliary to provide torque to the load 3 , or as a generator to convert excess power generated by the gas turbine 2 and not required by the load 3 into electrical energy, for example, to be injected into the grid G ​​to which the motor 6 can be connected.

[0047] In the hybrid powertrain 1', according to the same mechanism disclosed for the hybrid powertrain 1 according to the first embodiment, in the event that the gas turbine 2 or the motor 6 or both generate excessive torque on the transmission assemblies 4 and 8, the first clutch box 5 and the second clutch box 5' can both be broken.

[0048] Therefore, when the transmitted torque causes a force which exceeds the shear strength of the pin, ie exceeds a certain shear strength which can be preset by suitable design, the shear pin 553 breaks and the gas turbine 2 or the load 3 is mechanically decoupled.

[0049] The advantage of implementing a torque limiter device is that it allows avoiding over-design of the axis, which could jeopardize the feasibility of the project or limit the operating range of the turbo compressor powertrain. In addition, the axis is standardized and independent of the mechanical and electrical parameters of the electric machine, i.e., manufacturer-independent. A standardized powertrain axis with these characteristics developed for a brownfield can be easily replicated in a greenfield.

[0050] Another advantage of the present disclosure is the rotor dynamics benefits on the motor and compressor design.In addition, an enhanced range of operating modes (including a "boost mode") is available.

[0051] Another advantage of the present disclosure is that the clutch box can be used in both brownfield and greenfield applications. In addition, the axis can be easily validated without the need for detailed feasibility studies.

[0052] Another advantage of the present disclosure is that standardized axis integration is achieved regardless of the motor manufacturer, thereby achieving commercial benefits.

[0053] 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.

[0054] 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.

[0055] 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 besides the listed elements.

Claims

1. A hybrid powertrain system, comprising: a load, the load being driven by a torque; a gas turbine for generating a drive torque for driving the load; and A main transmission assembly, the main transmission assembly having: A clutch box, the clutch box comprising a housing and a clutch, the clutch being arranged in the housing; a first transmission shaft having one end mechanically connected to the gas turbine and another end mechanically connected to the clutch box; and a second transmission shaft having one end mechanically connected to the clutch box; The clutch box includes a torque limiting device, which is arranged in the accommodating housing. wherein the torque limiting device is connected between the clutch and the first transmission shaft and / or the second transmission shaft, and Wherein, when the torque transmitted to the clutch exceeds a threshold value, the torque limiting device mechanically decouples the clutch from the first transmission shaft and / or the second transmission shaft.

2. The hybrid powertrain system according to claim 1, wherein the torque limiting device comprises main body, a collar rotatably connected to the first transmission shaft, a sprocket rotatably connected to the clutch and arranged to face the collar, and one or more shear pins connecting the collar and the sprocket to withstand shear forces when torque is transferred from the collar to the sprocket, Wherein, in the event that the transmitted torque causes a force exceeding a shear strength threshold of the shear pin, the shear pin breaks to mechanically decouple the gas turbine. 3 . The hybrid powertrain system of claim 1 , wherein the clutch comprises a first clutch plate connected to the first transmission shaft and a second clutch plate connected to the second transmission shaft.

4. The hybrid powertrain system according to claim 3, wherein the collar is connected to the first transmission shaft via a journal bearing, and Wherein the sprocket is connected to the second shaft via a journal bearing. 5 . The hybrid powertrain system of claim 3 , wherein the other end of the second transmission shaft is connected to the load.

6. The hybrid powertrain of claim 1 , comprising an electric machine and another transmission assembly mechanically connecting the electric machine and the load, wherein the electric machine is configured to operate as an electric motor to transfer torque to the load and as a generator to receive torque from the load.

7. The hybrid powertrain system according to claim 3, The hybrid powertrain system includes an electric machine, wherein the second transmission shaft is connected to the motor, and The hybrid powertrain system includes another transmission assembly having Additional clutch box and a first transmission shaft having one end mechanically connected to the motor and another end mechanically connected to the clutch box, and A second transmission shaft has one end mechanically connected to the motor and another end mechanically connected to the load. 8 . The hybrid powertrain system of claim 1 , wherein the load is a compressor or a pump.

9. A clutch box, comprising: A housing; and A clutch, the clutch being arranged in the accommodating housing; The clutch box includes a torque limiting device, which is arranged in the accommodating housing. wherein the torque limiting device is connectable between the first transmission shaft and the clutch, and Wherein, when the torque transmitted to the clutch exceeds a threshold value, the torque limiting device mechanically decouples the clutch from the first transmission shaft.

10. A clutch box according to the preceding claim, wherein the torque limiting means comprises main body, a collar rotatably connectable to the first transmission shaft, a sprocket rotatably connected to the clutch and arranged to face the collar, and one or more shear pins connecting the collar and the sprocket to withstand shear forces when torque is transferred from the collar to the sprocket, Wherein in the event that the transmitted torque causes a force exceeding the shear strength threshold of the shear pin, the shear pin breaks to mechanically decouple the clutch.

11. The hybrid powertrain system according to claim 9, wherein the collar is connectable to the first transmission shaft via a journal bearing, and The sprocket can be connected to the second shaft via a journal bearing.

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