TURBOMACHINE MECHANISM INCLUDING A GEAR LINKAGE

Abstract

Mechanism (26) of a turbomachine (2) comprising a toothed link (25) having a first pair (27) of gears (27a, 27b) and a second pair (28, 29) of gears (28a, 28b, 29a, 29b), one of the gears of the first pair (27) and one of the gears of the second pair (28, 29) being rotationally linked with a primary shaft (30), the other gears of the first and second pairs (27-29) being rotationally linked with a secondary shaft (31), the toothed link (25) being configured to occupy the following positions: - a first position in which the gears of the first pair (27) are meshed and the gears of the second pair (28, 29) are dismeshed; - a second position in which the gears of the first pair (27) are disengaged and the gears of the second pair (28, 29) are engaged. Figure for the abbreviation: Figure 4

Description

Title of the invention: MECHANISM OF A TURBOMACHINE COMPRISING A GEAR LINKAGE Technical field of the invention

[0001] The present invention relates to a mechanism of a turbomachine comprising a toothed linkage, as well as to a method of changing the transmission ratio of the toothed linkage of such a mechanism. Technical background

[0002] A turbomachine generally includes various gear transmission mechanisms (or gear train) which allow the transmission (reversibly or irreversibly) of mechanical power taken from one or more driving devices to one or more receiving devices.

[0003] Typically, such a gear mechanism is found in an accessory housing, and allows the power taken from the turbomachine engine to be transmitted to the various accessories (pumps, electrical machines, oil separator, etc.) of the turbomachine, or vice versa.

[0004] Engine manufacturers today find that a gear mechanism is dedicated to motor and receiver devices, and that changing one of these devices generally entails the design of a new mechanism in which the gears are changed as well as the associated structure (and in particular the gear supports).

[0005] This lack of flexibility is not compatible with today's needs, and in particular with hybrid electric architectures which are evolving rapidly due to their many advantages (reduction of polluting and noise emissions, and increased safety).

[0006] By way of example, the aforementioned developments may concern the architectures themselves, or the associated accessories, namely for example the replacement of non-electrical accessories by more technically advanced electrical versions.

[0007] Today, engine manufacturers are therefore seeking to develop an evolving mechanism that can be easily and quickly adapted to the motor and receiver devices with which it is associated.

[0008] The objective of the present invention is therefore to provide a simple, effective and economical solution to the aforementioned problem. Summary of the invention

[0009] The invention thus proposes a mechanism for a turbomachine comprising a toothed linkage having at least one first pair of gears and a second pair of gears, the first and second pairs having distinct transmission ratios, the gears of the first pair having a module ml and a total number of teeth Ztl, the gears of the second pair having a module m2 which is equal to the module ml and a total number of teeth Zt2 which is equal to the total number of teeth Ztl, so that the gears of the first and second pairs have a constant center distance, one of the gears of the first pair and one of the gears of the second pair being rotationally linked with a primary shaft, the other gears of the first and second pairs being rotationally linked with a secondary shaft, the primary and secondary shafts being parallel to each other, the toothed linkage being configured to occupy the following positions: - a first position in which at least one first element is brought onto one of the shafts in order to position it axially, the gears of the first pair being meshed and the gears of the second pair being dismeshed; - a second position in which at least one second element is brought onto one of the shafts in order to position it axially, the gears of the first pair being disengaged and the gears of the second pair being engaged.

[0010] Such a mechanism thus makes it possible to change the transmission ratio of the toothed link without impacting the structure of the mechanism (and in particular the supports of the gear wheels) because the different pairs of gear wheels have a constant center distance.

[0011] The conservation of the constant center distance is directly related to the conservation of the module and the total number of teeth of the different pairs of the linkage.

[0012] The transmission ratio of each of the toothed links of the mechanism can be changed regardless of its position in the kinematic chain.

[0013] By way of example, the replacement of a receiving device (for example, an accessory) can now be carried out while retaining the existing structure of the mechanism. Indeed, such a replacement simply requires changing the gears engaged in the associated output link, so that the new receiving device can operate within the desired operating range.

[0014] Furthermore, in the same way, the replacement of a drive device (for example, the turbomachine motor) can be carried out while retaining the existing structure of the mechanism. Indeed, such a replacement simply requires changing the meshing gears of the various input links leading to the driven devices, so that each driven device retains its desired operating range.

[0015] The first and second elements can be spacers.

[0016] Each spacer can be arranged axially between a wall of a support and one of the gear wheels.

[0017] The present invention also relates to an accessory housing for a turbomachine comprising a mechanism as described above.

[0018] The present invention also relates to a turbomachine comprising a mechanism as described above, or an accessory housing as described above.

[0019] The present invention finally relates to a method of changing the transmission ratio of a toothed link of a mechanism of a turbomachine, the toothed link comprising a first pair of gears meshing with each other, the gears of the first pair being respectively centered on axes A, B, P, S parallel to each other, the gears of the first pair having a module ml and a total number of teeth Ztl, the method comprising a step consisting of changing the transmission ratio of the toothed link by disengaging the gears of the first pair, and by engaging gears of a second pair, the gears of the second pair having a module m2 which is equal to the module ml and a total number of teeth Zt2 which is equal to the total number of teeth Ztl, so that the gears of the first and second pairs have a constant center distance.

[0020] The method according to the invention may comprise one or more of the following features and / or steps, taken individually or in combination with each other: - one of the gears of the first pair and one of the gears of the second pair are rotationally linked with a primary shaft, the other gears of the first and second pairs being rotationally linked with a secondary shaft, the primary and secondary shafts being parallel to each other, the toothed linkage being configured to occupy the following positions: — a first position in which at least one first element is brought onto one of the shafts in order to position it axially, the gears of the first pair being meshed and the gears of the second pair being dismeshed; — a second position in which at least one second element is brought onto one of the shafts in order to position it axially, the gears of the first pair being disengaged and the gears of the second pair being engaged; the step in the process comprising the substeps consisting of: — remove the first element from the corresponding tree; — report the second element on the corresponding tree; - the first and second elements are spacers; - each spacer is positioned axially between a wall of a support and one of the gear wheels. Brief description of the figures

[0021] The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0022] [Fig-1] [Fig.1] is a schematic view of an accessory housing located in a reference configuration;

[0023] [Fig.2] [Fig.2] is a view similar to [Fig.1] in which the housing accessories are configured according to a first alternative;

[0024] [Fig.3] [Fig.3] is a view similar to Figures 1 and 2 in which the housing accessories are configured according to a second alternative;

[0025] [Fig.4] [Fig.4] is a view of a toothed linkage of a mechanism according to the invention, the toothed linkage occupying a first position;

[0026] [Fig.5] [Fig.5] is a view similar to [Fig.4] in which the toothed linkage occupies second position. Detailed description of the invention

[0027] Figure [1] schematically represents an accessory housing 1 of a turbomachine 2.

[0028] The accessory housing 1 here includes three accessories 3-5 whose rotors are coupled in rotation with the engine 6 of the turbomachine 2 via a gear mechanism 7 (or gear train).

[0029] Accessories 3-5 are for example electrical machines (generator / electric generator, starter, etc.), pumps (fuel pump, oil pump, etc.), oil separator, etc.

[0030] More specifically, as illustrated in [Fig. 1], the rotor of the first accessory 3 is rotationally coupled to the motor 6 via a first gear 8 which comprises a driving gear 8a and a driven gear 8b. The driving and driven gears 8a and 8b are respectively free to rotate about an axis A and an axis B which are parallel to each other.

[0031] The rotor of the second accessory 4 is rotationally coupled to the motor 6 via a second gear 9 which comprises a driving gear 9a and a driven gear 9b. The driving and driven gears 9a, 9b are respectively free to rotate about axis A and an axis C which is parallel to axes A and B. The driving gears 8a, 9a of the first and second gears 8, 9 are here carried by the same shaft 10.

[0032] The rotor of the third accessory 5 is coupled in rotation with the motor 6 via the second gear 9, and the third and fourth gears 11, 12.

[0033] The various gears 8, 9, 11, 12 of the mechanism 7 are here in external contact.

[0034] In the following description, a method for changing the transmission ratio of a toothed link 8 (for example formed by a gear) of a mechanism 7 of the turbomachine 2 will be presented in general terms.

[0035] As a preliminary point, the toothed linkage 8 comprises a first pair 8 of gears 8a, 8b meshing with each other. The gears 8a, 8b of the first pair 8 are respectively centered on axes A, B parallel to each other. The gears 8a, 8b of the first pair 8 have a module ml and a total number of teeth Ztl.

[0036] According to the invention, the method for changing the transmission ratio of the toothed link 8 comprises a step consisting of changing the transmission ratio of the toothed link 8 by disengaging the gears 8a, 8b of the first pair 8, and by engaging gears 14a, 14b, 16a, 16b of a second pair 14, 16, the gears 14a, 14b, 16a, 16b of the second pair 14, 16 having a module m2 which is equal to the module ml and a total number of teeth Zt2 which is equal to the total number of teeth Ztl, so that the gears 8a, 8b, 14a, 14b, 16a, 16b of the first and second pairs 8, 14, 16 have a constant center distance.

[0037] As indicated above, such a process thus makes it possible to change the transmission ratio of a toothed link 8 of the mechanism 7 without impacting the structure of the mechanism 7 (and in particular the supports of the gear wheels) because the different pairs 8, 14, 16 of gear wheels have a constant center distance.

[0038] The conservation of the constant center distance is directly related to the conservation of the module and the total number of teeth of the different pairs 8, 14, 16 of the link 8.

[0039] Such a method can be applied to each of the toothed links of the mechanism regardless of its position in the kinematic chain.

[0040] The module of a gear is generally a normalized value which corresponds to the quotient of the pitch diameter of the gear by the number of teeth.

[0041] Furthermore, the total number of teeth of a pair of gears corresponds to the sum of the number of teeth of the two gears of that pair.

[0042] In the following description, examples of application of the method described above to the accessory housing 1 initially described will be presented.

[0043] A first example of application is illustrated in [Fig.2], namely the change or replacement of the first accessory 3 by a new accessory 13 which is distinct from the first accessory 3 and which has a different operating range from that of the first accessory 3.

[0044] This difference in operating range implies a change in the transmission ratio of the first gear 8 alone, the other gears 9, 11, 12 not being modified in order not to disrupt or alter the operation of the other accessories 4, 5.

[0045] To change the transmission ratio of the first gear 8 which forms a toothed link, by application of the process described above, it is necessary to disengage (or uncouple) the gear wheels 8a, 8b of the first gear 8 and to engage (or couple) a new pair 14 of gear wheels 14a, 14b which has a transmission ratio adapted to the new accessory 13.

[0046] The gear wheels 14a, 14b of the new pair 14 have a module which is equal to that of the gear wheels 8a, 8b of the first gear 8, and a total number of teeth which is equal to the total number of teeth of the gear wheels 8a, 8b of the first gear 8.

[0047] The gears 14a, 14b of the new pair 14 thus have a center distance which is equal to that of the gears 8a, 8b of the first gear 8, and in other words the gears 14a, 14b of the new pair 14 are respectively mobile in rotation around the axes A and B.

[0048] A second application example is illustrated in [Fig.3], namely the change or replacement of the original motor 6 by a new motor 15 which is distinct from the original motor 6 and which has a different operating range from that of the original motor 6.

[0049] This difference in operating range implies a change in the transmission ratio of the input gears 8, 9 only, namely the first and second gears 8, 9, so that each accessory 3-5 retains its desired operating range.

[0050] To change the transmission ratio of the first gear 8 which forms a toothed link, by application of the process described above, it is necessary to disengage the toothed wheels 8a, 8b of the first gear 8 and to engage a new pair 16 of toothed wheels 16a, 16b which has a transmission ratio adapted to the new motor 15.

[0051] The gear wheels 16a, 16b of the new pair 16 have a module which is equal to that of the gear wheels 8a, 8b of the first gear 8, and a total number of teeth which is equal to the total number of teeth of the gear wheels 8a, 8b of the first gear 8.

[0052] The gear wheels 16a, 16b of the new pair 16 thus have a center distance which is equal to that of the gear wheels 8a, 8b of the first gear 8, and in other words the gear wheels 16a, 16b of the new pair 16 are respectively mobile in rotation around the axes A and B.

[0053] The same reasoning applies to change the transmission ratio of the second gear 9, so the gears 9a, 9b of the second gear 9 are disengaged and gears 17a, 17b of a new pair 17 are engaged.

[0054] In the following description, a mechanism 26 comprising a toothed link 25 will be presented, the transmission ratio of which can be changed in accordance with the method previously described.

[0055] As illustrated in figures 4 and 5, the toothed linkage 25 of the mechanism 26 comprises a first pair 27 of gears 27a, 27b, a second pair 28 of gears 28a, 28b and a third pair 29 of gears 29a, 29b.

[0056] The first, second and third pairs 27-29 exhibit distinct transmission ratios.

[0057] More specifically, the first pair 27 comprises an upper gear 27a and a lower gear 27b. Similarly, the second pair 28 comprises an upper gear 28a and a lower gear 28b. And similarly, the third pair 29 comprises an upper gear 29a and a lower gear 29b.

[0058] The gears 27a, 27b, 28a, 28b, 29a, 29b of the first, second and third pairs 27-29 have the same module. Furthermore, the gears 27a, 27b, 28a, 28b, 29a, 29b of the first, second and third pairs 27-29 have the same total number of teeth.

[0059] As illustrated in Figures 4 and 5, the upper gears 27a, 28a, 29a of the first, second, and third gear pairs 27-29 are rotationally linked with a primary shaft 30 that is free to rotate about a primary axis P. The lower gears 27b, 28b, 29b of the first, second, and third gear pairs 27-29 are rotationally linked with a secondary shaft 31 that is free to rotate about a secondary axis S. The primary and secondary shafts 30, 31 are parallel to each other and supported by upstream and downstream walls 32, 33 of a support 34. The upper gears 27a, 28a, 29a (and similarly the lower gears 27a, 28b, 29b) can be rotationally linked with the primary shaft 30 via nuts.

[0060] The meshing of the different couples 27-29 is here in external contact.

[0061] As illustrated in [Fig. 4], the toothed linkage 25 can occupy a first position in which a spacer 35 is attached to the primary shaft 30 in order to position it axially in a first position, with the gears 27a, 27b of the first pair 27 meshed, and the gears 28a, 28b, 29a, 29b of the second and third pairs 28, 29 disengaged. The spacer 35 is arranged axially between the upstream wall 32 and the upper gear 27a of the first pair 27.

[0062] As illustrated in [Fig. 5], the toothed linkage 25 can occupy a second position in which spacers 36a, 36b are attached to the primary shaft 30 in order to position it axially in a second position, the gears 28a, 28b of the second pair 28 being meshed, and the gears 27a, 27b, 29a, 29b of the first and third pairs 27, 29 being disengaged. A first spacer 36a is arranged axially between the upstream wall 32 and the upper gear 27a of the first pair 27, and a second spacer 36b is arranged axially between the downstream wall 33 and the upper gear 29a of the third pair 29.

[0063] The toothed link 25 can occupy a third position (not shown) in which the toothed wheels 29a, 29b of the third pair 29 are meshed, the toothed wheels 27a, 27b, 28a, 28b of the first and second pairs 27, 28 being disengaged.

[0064] To change the transmission ratio of the toothed linkage 25, and for example to move from the first position (the gears 27a, 27b of the first pair 27 are meshed, [Fig. 4]) to the second position (the gears 28a, 28b of the second pair 28 are meshed, [Fig. 5]), the step of the process described above herein comprises the substeps of: - remove the spacer 35 from the primary shaft 30; - attach spacers 36a, 36b to the primary tree 30.

Claims

Demands

1. Mechanism (26) of a turbomachine (2) comprising a toothed linkage (25) having at least a first pair (27) of gears (27a, 27b) and a second pair (28, 29) of gears (28a, 28b, 29a, 29b), the first and second pairs (27-29) having distinct transmission ratios, the gears (27a, 27b) of the first pair (27) having a module ml and a total number of teeth Ztl, the gears (28a, 28b, 29a, 29b) of the second pair (28, 29) having a module m2 which is equal to the module ml and a total number of teeth Zt2 which is equal to the total number of teeth Ztl, so that the gears (27a, 27b, 28a, 28b, 29a, 29b) of the first and second pairs (27-29) have a constant center distance, one of the gears (27a, 27b) of the first pair (27) and one of the gears (28a, 28b, 29a, 29b) of the second pair (28, 29) being rotationally linked with a primary shaft (30),the other gears of the first and second pairs (27-29) being rotationally linked with a secondary shaft (31), the primary and secondary shafts (30, 31) being parallel to each other, the toothed linkage (25) being configured to occupy the following positions:, - a first position in which at least one first element (35) is brought onto one of the shafts (30, 31) in order to position it axially, the gear wheels (27a, 27b) of the first pair (27) being meshed and the gear wheels (28a, 28b, 29a, 29b) of the second pair (28, 29) being disengaged; - a second position in which at least one second element (36a, 36b) is brought onto one of the shafts (30, 31) in order to position it axially, the gear wheels (27a, 27b) of the first pair (27) being disengaged and the gear wheels (28a, 28b, 29a, 29b) of the second pair (28, 29) being engaged.

2. Mechanism (26) according to the preceding claim, characterized in that the first and second elements (35, 36a, 36b) are spacers (35, 36a, 36b).

3. Mechanism (26) according to the preceding claim, characterized in that each spacer (35, 36a, 36b) is arranged axially between a wall (32, 33) of a support (34) and one of the gear wheels.

4. Accessory housing (1) of a turbomachine (2) comprising a mechanism (26) according to any one of the preceding claims.

5. Turbomachine (2) comprising a mechanism (26) according to any one of claims 1 to 3, or an accessory housing (1) according to the preceding claim.

6. A method for changing the transmission ratio of a toothed linkage (8, 25) of a mechanism (7, 26) of a turbomachine (2), the toothed linkage (8, 25) comprising a first pair (8, 27) of gears (8a, 8b, 27a, 27b) meshing with each other, the gears (8a, 8b, 27a, 27b) of the first pair (8, 27) being respectively centered on axes (A, B, P, S) parallel to each other, the gears (8a, 8b, 27a, 27b) of the first pair (8, 27) having a module ml and a total number of teeth Ztl, the method comprising a step of changing the transmission ratio of the toothed linkage (8, 25) by disengaging the gears (8a, 8b, 27a, 27b) of the first pair (8, 27), and by meshing the gears (14a, 14b, 16a, 16b, 28a, 28b, 29a, 29b) of a second pair (14, 16, 28, 29), the gears (14a, 14b, 16a, 16b, 28a, 28b, 29a, 29b) of the second pair (14, 16, 28,29) having a module m2 which is equal to the module ml and a total number of teeth Zt2 which is equal to the total number of teeth Ztl, so that the gears of the first and second pairs (8, 14, 16, 27, 28, 29) have a constant center distance.

7. A method according to the preceding claim, characterized in that one of the gears (27a, 27b) of the first pair (27) and one of the gears (28a, 28b, 29a, 29b) of the second pair (28, 29) are rotationally linked with a primary shaft (30), the other gears of the first and second pairs (27-29) being rotationally linked with a secondary shaft (31), the primary and secondary shafts (30, 31) being parallel to each other, the toothed connection (25) being configured to occupy the following positions: - a first position in which at least one first element (35) is mounted on one of the shafts (30, 31) in order to position it axially, the gears (27a, 27b) of the first pair (27) being meshed and the gears (28a, 28b, 29a, 29b) of the second pair (28, 29) being disengaged;- a second position in which at least one second element (36a, 36b) is brought onto one of the shafts (30, 31) in order to position it axially, the gear wheels (27a, 27b) of the first;

8.

9. pair (27) being disengaged and the gear wheels (28a, 28b, 29a, 29b) of the second pair (28, 29) being engaged; the step in the process comprising the substeps consisting of: - remove the first element (35) from the corresponding tree (30, 31); - report the second element (36a, 36b) on the corresponding tree (30, 31). Method according to the preceding claim, characterized in that the first and second elements (35, 36a, 36b) are spacers (35, 36a, 36b). Method according to the preceding claim, characterized in that each spacer (35, 36a, 36b) is arranged axially between a wall (32, 33) of a support (34) and one of the gear wheels.

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