TURBOMACHINE MECHANISM INCLUDING A GEAR LINKAGE

Abstract

Mechanism (19) of a turbomachine (2) comprising a toothed linkage (18) having a first pair (20) of gears (20a, 20b) and a second pair (21) of gears (21a, 21b), the first and second pairs (20, 21) having distinct transmission ratios, the gears (20a, 20b) of the first pair (20) having a module m1 and a total number of teeth Zt1, the gears (21a, 21b) of the second pair (21) having a module m2 which is equal to the module m1 and a total number of teeth Zt2 which is equal to the total number of teeth Zt1, the gears (20a, 20b) of the first pair (20) or the gears (21a, 21b) of the second pair (21) each being attached and rotationally connected to a shaft (22) via a a removable fastening element (23) allowing the gears (20a, 20b) of the first pair (20) to be replaced by those of the second pair (21), or vice versa. Figure for the abbreviated version: 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, the gears of the first pair or the gears of the second pair each being brought together and connected in rotation with a shaft via a fixing element which is removable, so as to be able to replace the gears of the first pair with those of the second pair or vice versa.

[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] Each of the fastening elements can be a nut which cooperates with a threaded portion which is formed on the shaft.

[0016] The present invention also relates to an accessory housing for a turbomachine comprising a mechanism as described above.

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

[0018] The present invention finally relates to a method for changing the transmission ratio of a toothed linkage of a turbomachine mechanism, the toothed linkage comprising a first pair of gears meshing with each other, the gears of the first pair being respectively centered on axes A, B parallel to each other, the gears of the first pair having a module ml and a total number of teeth Ztl, the process comprising a step of changing the transmission ratio of the toothed link by disengaging the gears of the first pair, and 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.

[0019] 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: - The gears of the first pair are each attached and rotationally linked to a shaft via a removable fastening element; the process step chronologically comprises the following substeps: — dismantle the fasteners; — disassemble the gears of the first pair; — mount the gears of the second pair; — reassemble the fastening elements; - each of the fastening elements is a nut which cooperates with a threaded portion which is formed on the shaft. Brief description of the figures

[0020] 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:

[0021] [Fig-1] [Fig.1] is a schematic view of an accessory housing located in a reference configuration;

[0022] [Fig.2] [Fig.2] is a view similar to [Fig.1] in which the accessory housing is configured according to a first alternative;

[0023] [Fig.3] [Fig.3] is a view similar to figures 1 and 2 in which the accessory housing is configured according to a second alternative;

[0024] [Fig.4] [Fig.4] is a detailed view of a toothed link of a mechanism according to the invention. Detailed description of the invention

[0025] Figure [1] schematically represents an accessory housing 1 of a turbomachine 2.

[0026] 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).

[0027] Accessories 3-5 are for example electrical machines (generator / electric generator, starter, etc.), pumps (fuel pump, oil pump, etc.), oil separator, etc.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The various gears 8, 9, 11, 12 of the mechanism 7 are here in external contact.

[0032] In the following description, a general method of change of the transmission ratio of a toothed link 8 (for example formed by a gear) of a mechanism 7 of the turbomachine 2.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Such a method can be applied to each of the toothed links of the mechanism regardless of its position in the kinematic chain.

[0038] 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.

[0039] Furthermore, the total number of teeth in a pair of gears corresponds to the sum of the number of teeth in the two gears of that pair.

[0040] In the following description, examples of application of the process described above to the accessory housing 1 initially described will be presented.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] To change the transmission ratio of the first gear 8 that forms a toothed linkage, by applying the method described above, it is necessary to disengage the gears 8a, 8b of the first gear 8 and engage a new pair 16 of gears 16a, 16b which has a transmission ratio adapted to the new motor 15.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In the following description, a mechanism 19 comprising a toothed link 18 will be presented, the transmission ratio of which can be changed in accordance with the method previously described.

[0053] As illustrated in [Fig.4], the toothed linkage 18 of the mechanism 19 comprises a first pair 20 of gears 20a, 20b and a second pair 21 of gears 21a, 21b, the first and second pairs 20, 21 having distinct transmission ratios.

[0054] The gears 20a, 20b, 21a, 21b of the first and second pairs 20, 21 have the same module. Furthermore, the gears 20a, 20b, 21a, 21b of the first and second pairs 20, 21 have the same total number of teeth.

[0055] The gear wheels 20a, 20b of the first pair 20 are each attached and connected in rotation with a shaft 22 via a fixing element 23 which is removable (or detachable).

[0056] The gear wheels 20a, 20b are respectively mobile in rotation around an axis A and an axis B which are parallel to each other.

[0057] Advantageously, as illustrated in [Fig.4], the fastening element 23 is a nut 23 which cooperates with a threaded portion 24 which is formed on the shaft 22.

[0058] To change the transmission ratio of the toothed link 18, and in other words replace the toothed wheels 20a, 20b of the first pair 20 with those of the second pair 21, the step of the process described above here chronologically includes the sub-steps consisting of: - unscrewing the nuts 23; - disassemble the gear wheels 20a, 20b of the first pair 20; - mount the gear wheels 21a, 21b of the second pair 21 - screw back the nuts 23.

Claims

Demands

1. Mechanism (19) of a turbomachine (2) comprising a toothed linkage (18) having at least a first pair (20) of gears (20a, 20b) and a second pair (21) of gears (21a, 21b), the first and second pairs (20, 21) having distinct gear ratios, the gears (20a, 20b) of the first pair (20) having a module ml and a total number of teeth Ztl, the gears (21a, 21b) of the second pair (21) 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, such that the gears (20a, 20b, 21a, 21b) of the first and second pairs (20, 21) have a constant center distance, the gears (20a, 20b) of the first pair (20) or the gears (21a, 21b) of the second pair (21) each being attached and rotationally linked with a shaft (22) via a fastening element (23) which is removable, so as to be able to replace the gears (20a,20b) of the first pair (20) by those of the second pair (21) or vice versa.

2. Mechanism (19) according to the preceding claim, characterized in that each of the fastening elements (23) is a nut (23) which cooperates with a threaded portion (24) which is formed on the shaft (22).

3. Accessory housing (1) of a turbomachine (2) comprising a mechanism (19) according to any one of the preceding claims.

4. Turbomachine (2) comprising a mechanism (19) according to any one of claims 1 to 2, or an accessory housing (1) according to the preceding claim.

5. A method for changing the transmission ratio of a toothed linkage (8, 18) of a mechanism (7, 19) of a turbomachine (2), the toothed linkage (8, 18) comprising a first pair (8, 20) of gears (8a, 8b, 20a, 20b) meshing with each other, the gears (8a, 8b, 20a, 20b) of the first pair (8, 20) being respectively centered on axes (A, B) parallel to each other, the gears (8a, 8b, 20a, 20b) of the first pair (8, 20) 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, 18) by disengaging the gears (8a, 8b, 20a, 20b) of the first pair (8, 20), and by engaging toothed wheels (14a, 14b, 16a, 16b, 21a, 21b) of a second pair (14, 16,

6.

7. 21), the gear wheels (14a, 14b, 16a, 16b, 21a, 21b) of the second pair (14, 16, 21) 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 gear wheels of the first and second pairs (8, 14, 16, 20, 21) have a constant center distance. Method according to the preceding claim, characterized in that the gears (20a, 20b) of the first pair (20) are each attached and rotationally linked with a shaft (22) via a fastening element (23) which is removable, the step of the method comprising chronologically the substeps of: - dismantling the fastening elements (23); - disassemble the gear wheels (20a, 20b) of the first pair (20); - mount the gears (21a, 21b) of the second pair (21); - reassemble the fixing elements (23). Method according to the preceding claim, characterized in that each of the fastening elements (23) is a nut (23) which cooperates with a threaded portion (24) which is formed on the shaft (22).

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