Transmission mechanism with internal lubrication and associated electric propulsion unit

Abstract

A transmission mechanism with internal lubrication comprises: a housing; at least one driveshaft rotatable about an axis of rotation relative to the housing and including a toothed pinion; the utility model relates to a drive shaft assembly comprising a housing, a guide bearing supporting the drive shaft with respect to the housing, the guide bearing comprising a rolling element, the guide bearing being inserted into a cylindrical housing formed in the housing, characterized in that a protective plate covers the rolling element of the guide bearing in an axially contactless manner, the guide bearing is axially interposed between the bottom of the cylindrical housing and a protective plate, the protective plate comprising a lubricating fluid discharge channel located in a bottom portion of the plate with respect to the axis of rotation when the transmission mechanism is in a reference operating position. Also disclosed is an electric propulsion unit comprising an electric motor and the aforementioned transmission mechanism.

Description

Technical Field

[0001] This invention relates to the internal lubrication of components of a transmission mechanism, for example by splash lubrication, particularly a reduction gear mechanism. Background Technology

[0002] To lubricate the components of a transmission mechanism, particularly the rotary guide bearings and transmission elements, the known practice is to place the moving parts of the mechanism within an oil-containing housing, but without completely immersing the moving parts (e.g., the drive shaft supporting the pinion). Therefore, it is the movement of the transmission mechanism agitating the oil and spraying it throughout the entire interior space of the housing that, through splash lubrication, ensures the necessary lubrication for the entire mechanism, including the un-immersed parts.

[0003] Guide bearings, such as ball bearings, must always be lubricated, typically with a flow of lubricating oil through them. When they are insufficiently lubricated, guide bearings risk overheating. Conversely, overlubrication of guide bearings leads to reduced efficiency, especially at high speeds, thus degrading the overall performance of the reduction gear mechanism. A trade-off must be found between the need for adequate lubrication and the desire to minimize energy loss due to oil agitation, which tends to introduce excessive oil around the rolling elements of the guide bearing.

[0004] To control the flow of lubricating fluid within the guide bearing, an oil baffle can be placed at the bottom of the cylindrical housing containing the guide bearing. This oil baffle includes protrusions that guide the oil flow through the rear of the guide bearing, as disclosed in document EP2112405A1. The protrusions direct the oil flow into the drive shaft, allowing it to exit through the teeth of the pinion supported by the shaft. However, this oil baffle does not protect the guide bearing from oil splashing onto its front surface, which occurs when the oil is agitated. The uncontrolled flow of oil through the guide bearing results in significant energy loss.

[0005] Another drawback of this type of oil baffle is that it must be held in place within the housing by a complex shape, which increases the manufacturing cost of the housing. Utility Model Content

[0006] This invention aims to overcome the shortcomings of the prior art and proposes a transmission mechanism that provides both good lubrication of the guide bearing and low energy consumption at high speeds.

[0007] Therefore, according to a first aspect of this utility model, a transmission mechanism lubricated by splash lubrication is proposed, comprising:

[0008] shell;

[0009] At least one drive shaft, the at least one drive shaft being rotatable relative to the housing about a rotation axis of the drive shaft, and including a toothed pinion;

[0010] A guide bearing that supports a drive shaft relative to a housing, the guide bearing including rolling elements, and the guide bearing being inserted into a cylindrical portion formed in the housing.

[0011] The protective plate axially covers the rolling elements of the guide bearing without contact, the guide bearing being axially located between the bottom of the cylindrical part and the protective plate, the protective plate including a lubricating fluid discharge channel, which is located at the bottom part of the plate relative to the axis of rotation when the transmission mechanism is in the reference operating position.

[0012] A protective plate is positioned in front of the guide bearing, in other words, facing the pinion of the drive shaft, to prevent lubricating fluids, such as oil, from spraying into the guide bearing. Since lubricating oil no longer freely enters, the oil flow through the guide bearing is controlled.

[0013] Within the meaning of this utility model, the term "coverage" means both contact coverage and non-contact coverage.

[0014] Advantageously, the protective plate is axially positioned between the guide bearing and the toothed pinion. This prevents oil from being sprayed directly onto the teeth of the pinion.

[0015] Preferably, the guide bearing may include a rotating inner ring, a non-rotating outer ring that does not rotate relative to the housing, and rolling elements disposed between the rotating inner ring and the non-rotating outer ring, with a protective plate covering the available space between the non-rotating outer ring and the rotating inner ring of the guide bearing. For example, the guide bearing may be a ball bearing, a roller bearing, or a needle roller bearing.

[0016] Advantageously, the lubricating fluid discharge passage can be opened to the available space between the non-rotating outer ring and the rotating inner ring of the guide bearing.

[0017] According to a variation of this invention, the protective plate is attached to the non-rotating outer ring of the guide bearing. In this case, the protective plate covers the guide bearing in contact with the ground. The fact that the protective plate is attached to a fixed element of the transmission mechanism makes it possible to limit spraying inside the housing and limit frictional losses. For example, the protective plate may include attachment tabs that snap into an inner groove formed in the non-rotating outer ring.

[0018] Preferably, the protective plate covers the rotating inner ring of the guide bearing in a non-contact manner.

[0019] Preferably, the protective plate may partially cover the housing at least in the insertion region of the guide bearing formed on the housing. This increases the surface area for protection and improves control over the flow rate of the lubricating fluid entering the guide bearing.

[0020] According to a variation of this invention, the protective plate is axially supported on the housing, at least in the insertion region of the guide bearing. In this case, the protective plate contacts and covers the housing. The protective plate can then be attached to the housing. For example, the protective plate may include attachment tabs that snap into recesses formed in the cylindrical portion.

[0021] According to another variation of this invention, the protective plate covers the insertion area of ​​the guide bearing without contact. In this case, there is a few millimeters of axial space between the protective plate and the housing.

[0022] Advantageously, the protective plate may include a central hole into which the drive shaft is inserted.

[0023] Preferably, the housing may include an open channel in the upper part of the cylindrical housing, with a protective plate at least partially covering the channel. This improves control over the flow rate of the lubricating fluid entering the guide bearing.

[0024] According to one embodiment, the housing includes an open channel in the upper part of the cylindrical housing, a protective plate at least partially covering the channel, and the lubricating fluid discharge channel is arranged substantially on the opposite side of the channel relative to the axis of rotation. This guides the flow of lubricating oil into the guide bearing.

[0025] According to a variation of this invention, the lubricating fluid discharge channel is a groove that passes exactly through the thickness of the protective plate. In this variation, the groove has an elongated shape. For example, the groove has an oblong shape. The flow rate of the lubricating fluid exiting the guide bearing is thus controlled. In this variation, the groove is open on the outer periphery of the protective plate. The groove can also open into the available space between the non-rotating outer ring and the rotating inner ring of the guide bearing. This facilitates the discharge of lubricating fluid from the guide bearing.

[0026] According to another variation of the present invention, the lubricating fluid discharge channel is a rib stamped in the protective plate, the rib being open on one of the edges of the protective plate.

[0027] According to another variation of the present invention, the lubricating fluid discharge channel is a groove hollowed out in the protective plate, which is open on one of the edges of the protective plate.

[0028] Preferably, the insertion area of ​​the guide bearing may include a generally annular first rim surrounding the cylindrical portion and the guide bearing, with a protective plate contacting and covering the first rim.

[0029] Advantageously, the insertion region of the guide bearing may further include a generally annular second rim radially disposed outside the first rim and a groove disposed between the first and second rims, with a protective plate covering the insertion region up to the second rim. Therefore, cooling of the guide bearing can be improved without increasing the fluid volume inside the guide bearing. The protective plate contacts and covers the second rim.

[0030] Preferably, the first rim and the second rim can be concentric.

[0031] Advantageously, the recess in the insertion region may include a lubricating fluid inlet and a lubricating fluid outlet oriented vertically relative to the axis of rotation of the drive shaft, the fluid inlet and outlet being recesses formed in the second rim. This facilitates the flow of lubricating fluid around the guide bearing.

[0032] Preferably, the groove in the insertion area may include fins for heat exchange with the housing, the fins being distributed at an angle around the axis of rotation.

[0033] Advantageously, the protective plate can directly form the second rim and the first oil inlet and / or the second oil inlet.

[0034] According to an aspect of the present invention, the transmission mechanism may further include: a first transmission shaft housed in a housing, the first transmission shaft being guided by a first guide bearing to rotate about a first rotation axis and rotating integrally with at least one drive pinion; a second transmission shaft, the second transmission shaft being guided by a second guide bearing to rotate about a second rotation axis and rotating integrally with at least one intermediate pinion; and a third transmission shaft, the third transmission shaft being guided by a third guide bearing to rotate about a third rotation axis and rotating integrally with at least one driven pinion, wherein a protective plate axially and non-contactly covers the rolling elements of at least two guide bearings selected from the first, second, and third guide bearings.

[0035] Preferably, the first drive shaft, the second drive shaft, and the third drive shaft can be parallel to each other.

[0036] Advantageously, the protective plate allows at least two drive shafts to pass through it, the at least two drive shafts being selected from the first, second, and third drive shafts.

[0037] Preferably, the housing may include a molded or machined channel connecting the two cylindrical portions for inserting a guide bearing, with a protective plate covering the channel and thus forming a conduit for lubricating fluid to pass between the two cylindrical portions.

[0038] Advantageously, the transmission mechanism may include one or more gears, establishing a fixed transmission ratio greater than 1 between the driving pinion and the driven pinion.

[0039] Preferably, the transmission mechanism may further include a differential housed in a housing, with the third drive shaft constituting the input component of the differential.

[0040] This invention is more specifically applicable to reduction gear transmission mechanisms, particularly to reduction gears with a fixed ratio or two reduction ratios, to parallel shaft reduction gears, or to coaxial reduction gear devices including planetary gear systems, wherein the rotation axis of the electric motor is concentric with the output shaft of the planetary gear system.

[0041] According to another aspect of the present invention, it relates to an electric propulsion unit comprising an electric motor and a transmission mechanism, the transmission mechanism comprising all or some of the features described above, wherein the transmission shaft constitutes the output shaft of the electric motor or rotates integrally with the drive shaft of the electric motor.

[0042] Preferably, the stator of the electric motor can be attached to the housing. Attached Figure Description

[0043] Referring to the accompanying drawings and reading the following description, other features and advantages of this invention will become apparent:

[0044] Figure 1 An electric propulsion unit including a transmission mechanism according to a first embodiment of the present invention is partially shown.

[0045] Figure 2 It is in the reference operating position. Figure 1 A partial end view of the transmission mechanism.

[0046] Figure 3 yes Figure 2 The transmission mechanism is shown in a sectional view in a vertical plane, with the transmission mechanism in a reference operating position.

[0047] Figure 4 This is a detailed view of the transmission mechanism according to the second embodiment of the present utility model.

[0048] Figure 5 This is an end view of the transmission mechanism according to the third embodiment of the present utility model, with the transmission mechanism in a reference operating position.

[0049] Figure 6 yes Figure 5 A partial view of the transmission mechanism.

[0050] Figure 7 This is a partial view of the transmission mechanism according to the fourth embodiment of the present utility model.

[0051] For clarity, the same or similar elements are identified using the same reference numerals in all the accompanying drawings. Detailed Implementation

[0052] Figures 1 to 3 An electric propulsion unit 1 is shown, including a motor 60 and a transmission mechanism M according to a first embodiment of the present invention.

[0053] Motor 60 may be, for example, an induction motor, including rotor 62 and stator 61, powered by a battery via a current converter. Figure 1 (Not shown in the image) is powered by three-phase AC power.

[0054] The motor 60 is held on the housings 40a and 40b. The housings typically consist of a main housing 40a that supports the motor 60 and a closed housing 40b that is supported on the main housing 40a in a mating plane 48, so as to seal the closed cavity defined by the main housing 40a and the closed housing 40b.

[0055] The motor 60 rotates the first drive shaft 10 that enters the housing 40a. The first drive shaft 10 constitutes the input shaft of the transmission mechanism M, which also includes a second drive shaft 20 and a third drive shaft 30 that constitutes the output shaft of the transmission mechanism M.

[0056] The second transmission shaft 20, which constitutes the intermediate shaft of the transmission mechanism M, is parallel to the input shaft 10 and the output shaft 30 of the transmission mechanism M.

[0057] like Figure 3 As shown, the input shaft 10 is aligned with the drive shaft 63 of the motor 60 relative to the housing 40a and supports at least one gear, referred to in this case as the drive pinion 11, which is rotatably connected to the transmission shaft. The input shaft 10 is guided to rotate by two guide bearings 100a and 100b, thereby rotating relative to the housing 40a about a first axis of rotation X1.

[0058] The guide bearing 100a, which supports the first drive shaft relative to the housing, specifically includes a rolling element 103, in this case, bearing balls. The guide bearing 100a is inserted into a cylindrical fitting 41 formed in the housing 40a.

[0059] To lubricate the various components of the transmission mechanism M, housings 40a and 40b contain lubricating oil. The guide bearings and pinion of the transmission shaft are partially immersed in the oil. Therefore, it is the movement of the transmission mechanism agitating the oil and spraying it throughout the entire interior space of the housings that ensures the necessary lubrication of the entire mechanism, including the unimmersed components, through splash lubrication.

[0060] In a first embodiment of the present invention, a protective plate 70 partially covers the housing in the insertion region 50 of the guide bearing formed on the housing. The insertion region 50 of the guide bearing includes a substantially annular first rim 51 surrounding the cylindrical housing 41 and the guide bearing 100a. The protective plate 70 is axially supported on the housing 40a at least in the insertion region 50 of the guide bearing. In this case, the protective plate 70 contacts and covers the housing 40a.

[0061] A protective plate 70 is axially arranged between the drive pinion 11 and the guide bearing 100a. The protective plate 70 is positioned in front of the guide bearing, in other words, opposite to the drive pinion of the drive shaft, so as to prevent lubricating fluid, such as oil, from being sprayed into the guide bearing.

[0062] The output shaft 30 supports at least one driven pinion 31 for rotation. The output shaft 30 also includes a connector that is rotatably fixed to the planetary carrier of the differential 32, or the planetary carrier constituting the differential 32. Depending on the desired characteristics, the differential 32 can be an open differential or a limited-slip differential. The output shaft 30 is guided to rotate by two guide bearings 300a and 300b, thereby rotating relative to the housing 40a about a third axis of rotation X3.

[0063] Similar to the input shaft 10 and the output shaft 30, the intermediate shaft 20 is guided by multiple guide bearings 200a and 200b to rotate around the second rotation axis X2, and supports two intermediate pinions 21 and 22 that rotate together. The first intermediate pinion 21 and the driving pinion 11 of the input shaft 10 form a first reduction gear, and the second intermediate pinion 22 and the driven pinion 31 of the output shaft 30 form a second reduction gear.

[0064] The first, second, and third rotation axes X1, X2, and X3 are parallel to each other. The first rotation axis X1 and the third rotation axis X3 are located in the reference plane P of the transmission mechanism M. The second rotation axis X2 is not located in the reference plane P.

[0065] The diameter and number of teeth of the driving pinion 11 are smaller than those of the intermediate pinion 21 of the intermediate shaft 20 that forms the first reduction gear. Similarly, the diameter and number of teeth of the second intermediate pinion 22 of the intermediate shaft 20 that forms the second reduction gear are smaller than those of the driven pinion 31 of the output shaft 30. Therefore, the transmission mechanism M is a reduction gear with a constant transmission ratio.

[0066] In the remainder of this specification, the reference operating position of the transmission mechanism M is defined as its three-dimensional orientation when mounted in a horizontal vehicle. In this reference operating position, the second rotation axis X2 is located above the reference plane P. In the remainder of this specification, unless otherwise stated, the invention will be described in the reference operating position.

[0067] Figure 2 The transmission mechanism M is shown in a partial, simplified end view, depicting a first transmission shaft 10 rotated by a guide bearing 100a and in a reference operating position.

[0068] During operation, the housing 40a is filled with lubricating oil up to a set limit, which corresponds to the oil level at the stationary plane. When the transmission mechanism is in the reference operating position, the oil level at the stationary plane is horizontal.

[0069] A portion of the reference plane P of the transmission mechanism M, defined by the input shaft 10 and the output shaft 30, lies above the oil surface of the stationary plane.

[0070] An oil collection tank 80 is disposed between the first drive shaft 10 and the third drive shaft 30. The oil collection tank 80 retains some oil flowing back from the components of the transmission mechanism, which are splash-lubricated in the oil. The oil collection tank 80 has at least one upper opening 82 above the oil surface on a stationary plane, and an outlet orifice 81 below the upper opening 82. Therefore, lubricating oil can be specifically supplied to the upper region of the housing 40a.

[0071] The oil collection tank 80 enables a dynamic oil level to be provided according to the rotational speed of the input shaft 10. More specifically, as the speed increases, the oil collection tank 80 lowers the oil level by retaining some oil flowing back from the transmission components that are splash-lubricated in oil.

[0072] In a stationary state, or in other words, in a non-operating state, the oil collection tank 80 above the oil level at the stationary plane is empty, and the oil level corresponds to the oil level at the stationary plane. When the transmission mechanism M operates at a very low speed, the maximum oil level changes very little. This is because the driven pinion 31 rotates at a low speed, and since the driven pinion 31 is the largest gear in the transmission mechanism M, it is the gear most likely to spray oil across the housing 40a.

[0073] The faster the drive shaft rotates, the more oil is sprayed across the housing 40a via the rotation of the pinion gear. When the oil is sprayed into the housing 40a, it falls back down.

[0074] To mechanical parts such as pinions or bearings; and / or

[0075] Entering the bottom of the outer shell 40a where oil sediment has settled; and / or

[0076] Enter Figure 3 The oil collection tank 80 shown.

[0077] The oil collected in the oil collection tank 80 is then partially fed into the channel 45 formed in the housing 40a so that it can be delivered to the guide bearing 100a, as shown. Figure 3 As indicated by the arrow in the diagram. Channel 45 opens at the top of the cylindrical part 41.

[0078] To control the flow of lubricating fluid through the guide bearing 100a, the transmission mechanism M includes a protective plate 70 that axially and non-contactly covers the rolling element 103 of the guide bearing 100a. The guide bearing 100a is axially positioned between the bottom 41a of the cylindrical housing 41 and the protective plate 70. The protective plate 70 at least partially covers the channel 45 and includes a lubricating fluid discharge channel 72, which is located in the bottom portion of the plate relative to the first axis of rotation X1 when the transmission mechanism is in the reference operating position.

[0079] Therefore, the lubricating oil is delivered toward the guide bearing 100a until it reaches the available space between the bottom 41a of the cylindrical housing 41 and the rear surface of the guide bearing 100a. Due to gravity, the lubricating fluid descends along the channel 45 and then enters the cavity formed by the cylindrical housing 40a, and then flows out via the recess 55 formed in the housing and the lubricating fluid discharge channel 72 formed on the protective plate 70. When the transmission mechanism M is in the reference operating position, the lubricating fluid discharge channel 72 is a groove located in the bottom of the protective plate relative to the axis of rotation.

[0080] The guide bearing 100a includes a rotating inner ring 101, a non-rotating outer ring 102 relative to the housing, and a rolling element 103 disposed between the two rings. A protective plate 70 covers the available space between the non-rotating outer ring 102 and the rotating inner ring 101 of the guide bearing.

[0081] In this example, the lubricating fluid discharge channel 72 is a groove that passes exactly through the thickness of the protective plate. The groove 72 has an elongated shape, more specifically, an oblong shape. The groove 72 opens into the available space between the outer ring 102 and the rotating inner ring 101 of the guide bearing. When the transmission mechanism M is in the reference operating position, the lubricating fluid discharge channel 72 is oriented downwards relative to the first axis of rotation X1. The geometry and dimensions of the groove 72 allow for adjustment of the discharge rate of the lubricating fluid within the guide bearing.

[0082] To facilitate integration into the transmission mechanism, the protective plate 70 includes a central hole 73 into which the first drive shaft 10 is inserted. The protective plate 70 is attached to the non-rotating outer ring 102 of the guide bearing. In this configuration, the protective plate contacts and covers the guide bearing. The protective plate 70 also includes an attachment tab 74 that engages in an inner groove 104 formed in the non-rotating outer ring.

[0083] Now refer to Figure 4A second embodiment of the present invention is described, which differs from the previous embodiment in that the lubricating fluid discharge channel 72 is specifically arranged relative to the first rotation axis X1. In this embodiment, the lubricating fluid discharge channel 72 is a groove that passes exactly through the thickness of the protective plate 70. The groove 72 has an elongated oval shape and is open to the available space between the outer ring 102 and the rotating inner ring 101 of the guide bearing. However, the elongated oval shape is asymmetrical relative to the vertical plane passing through the first rotation axis X1. Therefore, the groove 72 is angled to increase the oil level in the rotational direction. When rotating at low speed, a certain amount of oil remains in the guide bearing because the oil does not rise sufficiently to the bottom of the groove 72. When rotating at high speed, the oil is rotated by the rolling element 103 and reaches the bottom of the groove 72, thereby allowing it to be discharged. The amount of oil in the guide bearing is thus reduced.

[0084] Now refer to Figure 5 and Figure 6 The third embodiment of the present invention is described, which differs from the first embodiment in that the protective plate 70 axially covers the rolling elements 103 of the first, second and third guide bearings 100a, 200a and 300a.

[0085] Since the first drive shaft 10, the second drive shaft 20, and the third drive shaft 30 are parallel to each other, the protective plate allows the first, second, and third drive shafts 10, 20, and 30 to pass through it.

[0086] like Figure 6 As shown, the housing 40a includes a molded channel 45 connecting the two cylindrical housings 41 for inserting a guide bearing. A protective plate 70 covers the channel 45, thereby forming a conduit between the two cylindrical housings for the passage of lubricating fluid 46.

[0087] At the third drive shaft 30, the protective plate 70 has a groove 72a that is open on the outer periphery of the plate.

[0088] Now refer to Figure 7 The fourth embodiment of the present invention is described, which differs from the first embodiment in that the insertion region of the guide bearing 50 has a different geometry.

[0089] In this fourth embodiment, the insertion region 50 of the guide bearing 100a includes a first rim 51 that is substantially annular around the cylindrical placement portion 41 and the guide bearing, a second rim 52 that is substantially annular radially arranged outside the first rim, and a groove 53 arranged between the first rim 51 and the second rim 52.

[0090] The protective plate 70 covers the insertion area 50 up to the second rim 52. For greater efficiency, the protective plate 70 also covers the first rim 51 and the second rim 52 in contact with the ground. The first rim and the second rim are concentric.

[0091] The recess 53 in the insertion region includes a lubricating fluid inlet 46 and a lubricating fluid outlet 47 oriented vertically relative to the rotation axis X1 of the first drive shaft 10. The fluid inlet 46 and the fluid outlet 47 are recesses 55 formed in the second rim 52. This facilitates the flow of lubricating fluid around the guide bearing.

[0092] Finally, the recess 53 of the insertion area 50 includes fins 58 for heat exchange with the housing 40a, which are distributed at an angle around the first axis of rotation X1.

[0093] In this fourth embodiment, the lubricating oil collected by the oil collection tank 80 is sent to the lubricating fluid inlet 46 formed in the housing 40a, so as to be partially delivered to the guide bearing 100a and partially delivered to the groove 53 of the insertion region 50, such as... Figure 7 As shown by the arrow in the image.

[0094] Lubricating oil flows through conduit 48 toward the guide bearing 100a until it reaches the available space between the bottom 41a of the cylindrical housing 41 and the rear surface of the guide bearing 100a. Due to gravity, the lubricating fluid enters the cavity formed by the cylindrical housing 40a and then flows out via a recess 55 formed in the housing and a lubricating fluid discharge channel 72 formed on the protective plate 70. The lubricating fluid discharge channel 72 is, for example, a groove hollowed out in the protective plate, which opens relative to the axis of rotation on one of the edges of the protective plate when the transmission mechanism M is in the reference operating position.

[0095] The lubricating oil flow through the groove 53 is divided into two parts, so that the first rim 51 can be cooled and thus the guide bearing 100a can be cooled without introducing more lubricating oil into the latter.

[0096] Of course, the examples depicted in the figures and described above are provided by way of non-limiting illustration only. To provide further embodiments, it is explicitly stated that various illustrated embodiments may be combined.

[0097] According to a variant not shown, the transmission mechanism M is a coaxial type that includes a planetary gear system.

[0098] The above-mentioned transmission mechanism is a reduction mechanism with a constant transmission ratio and an intermediate shaft. However, this utility model can also be applied to mechanisms with multiple intermediate shafts or without intermediate shafts, mechanisms with multiple transmission ratios, and / or mechanisms where the ratio of the input gear to the output gear is less than 1.

[0099] The aforementioned transmission mechanism M is a reduction gear mechanism that uses splash lubrication for internal lubrication. However, this invention can also be applied to reduction gear mechanisms that use pressure for internal lubrication, wherein oil is delivered via pipes or hoses to the main points of the reduction gear to be lubricated. The oil then falls back to the bottom of the housing under gravity. In another example, a mechanical or electric pump can be used to supply fluid under pressure through pipes or hoses.

Claims

1. A transmission mechanism (M) with internal lubrication, comprising: - a housing (40a, 40b); - at least one transmission shaft (10, 20, 30) rotatable with respect to the housing about an axis of rotation (XI, X2, X3) of the transmission shaft and comprising a toothed pinion; - a guide bearing (100a, 200a, 300a) supporting the transmission shaft with respect to the housing, the guide bearing comprising rolling elements (103), the guide bearing being inserted in a cylindrical housing (41) formed in the housing, characterized in that a protection plate (70) axially covers the rolling elements of the guide bearing, the guide bearing being axially interposed between a bottom portion (41a) of the cylindrical housing (41) and the protection plate, the protection plate comprising a lubricating fluid evacuation channel (72, 72a) located at a bottom portion of the plate with respect to the axis of rotation when the transmission mechanism (M) is in a reference operating position.

2. The transmission mechanism (M) according to claim 1, characterized in that the guide bearing (100a, 200a, 300a) comprising a rotating inner ring (101, 201, 301), a non-rotating outer ring (102, 202, 302) not rotating with respect to the housing (40a, 40b) and rolling elements (103, 203, 303) arranged between the rotating inner ring and the non-rotating outer ring, the protection plate covering the available space between the non-rotating outer ring and the rotating inner ring of the guide bearing.

3. The transmission mechanism (M) according to claim 2, characterized in that the lubricating fluid evacuation channel (72, 72a) opening onto the available space between the non-rotating outer ring (102, 202, 302) and the rotating inner ring (101, 201, 301) of the guide bearing.

4. Transmission mechanism (M) according to any one of the preceding claims, characterized in that, the lubricating fluid evacuation channel (72, 72a) is a slot passing exactly through the thickness of the protection plate (70).

5. The transmission mechanism (M) according to claim 4, characterized in that the slot has an elongated shape.

6. The transmission mechanism (M) according to claim 4, characterized in that the slot opens on the outer periphery of the protection plate (70).

7. The transmission mechanism (M) according to any one of claims 1 to 3, characterized in that the protection plate (70) at least partially covers the housing (40a, 40b) in the insertion area (50) of the guide bearing formed on the housing.

8. The transmission mechanism (M) according to claim 7, characterized in that the protection plate (70) is axially supported on the housing at least in the insertion area (50) of the guide bearing.

9. The transmission mechanism (M) according to any one of claims 1 to 3, characterized in that the housing (40a, 40b) comprises a channel (45) opening in an upper portion of the cylindrical housing (41), the protection plate (70) at least partially covering the channel (45) and the lubricating fluid evacuation channel (72, 72a) being arranged substantially on opposite sides of the channel (45) with respect to the axis of rotation.

10. The transmission mechanism (M) according to any one of claims 1 to 3, characterized in that the protection plate (70) is attached to the non-rotating outer ring of the guide bearing and / or to the housing (40a, 40b).

11. The transmission mechanism (M) according to any one of claims 1 to 3, characterized in that the protection plate (70) comprises a central hole in which the transmission shaft (10, 20, 30) is inserted.

12. The transmission mechanism (M) according to claim 7, characterized in that The insertion area (50) of the guide bearing comprises a substantially annular first rim (51) surrounding the cylindrical housing (41) and the guide bearing (100a, 200a, 300a), the protection plate (70) contactingly covering the first rim (51).

13. Transmission mechanism (M) according to claim 12, characterized in that The insertion area (50) of the guide bearing further comprises a substantially annular second rim (52) radially arranged outside the first rim (51) and a recess (53) arranged between the first rim and the second rim, the protection plate (70) covering the insertion area up to the second rim.

14. The transmission mechanism (M) according to any one of claims 1 to 3, characterized in that The transmission mechanism further comprises, housed in the casing (40a, 40b): a first transmission shaft (10) guided in rotation about a first rotation axis (X1) by a first guide bearing (100a, 100b) and integral with at least one driving pinion (11); a second transmission shaft (20) guided in rotation about a second rotation axis (X2) by a second guide bearing (200a, 200b) and integral with at least one intermediate pinion (21, 22); and a third transmission shaft (30) guided in rotation about a third rotation axis (X3) by a third guide bearing (300a, 300b) and integral with at least one driven pinion (31), and the protection plate axially and contactlessly covering the rolling elements of at least two guide bearings selected from the first, second and third guide bearings.

15. The transmission mechanism (M) according to claim 2, characterized in that The protection plate comprises an attachment tab snapped into an internal recess formed in a non-rotating outer ring.

16. The transmission mechanism (M) according to claim 1, characterized in that The lubrication fluid evacuation channel is a rib stamped in the protection plate, the rib opening on one of the edges of the protection plate.

17. The transmission mechanism (M) according to claim 1, characterized in that The lubrication fluid evacuation channel is a groove hollowed in the protection plate, the groove opening on one of the edges of the protection plate.

18. The transmission mechanism (M) according to claim 14, characterized in that The protection plate passes through it at least two transmission shafts selected from a first, second and third transmission shaft.

19. The transmission mechanism (M) in accordance with claim 5, characterized in that The slot has an oblong shape.

20. An electric propulsion unit, characterized by The electric propulsion unit comprises an electric motor (60) and a transmission mechanism (M) according to any one of the preceding claims, the transmission shafts (10, 20, 30) constituting the output shaft of the electric motor (60) or rotating integrally with the drive shaft (63) of the electric motor.

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