Mechanical gearbox with parallel shaft lines
The mechanical gearbox with parallel shaft lines and stiffening bars addresses casing stiffness issues in hybrid vehicles, enhancing rigidity and reducing noise and vibrations by using aluminum alloy bars to stabilize casings under high torque and dual power sources.
Patent Information
- Application Number
- FR2022012495
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-11-29
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2042-11-29
AI Technical Summary
Existing gearboxes face issues with bearing and gear tooth misalignments due to insufficient casing stiffness, particularly when connected to both thermal engines and electric motors, leading to casing twisting and biasing, which conventional methods like tooth correction and casing ribbing cannot adequately address.
A mechanical gearbox with parallel shaft lines featuring stiffening bars fixed between casings to enhance rigidity, using aluminum alloy bars with specific dimensions and fixation methods to prevent casing twisting and associated biasing.
The solution provides increased casing rigidity, reducing noise and vibrations, simplifying manufacturing, and improving the gearbox's performance in hybrid vehicles by effectively managing high engine torque and dual power sources.
Smart Images
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Abstract
Description
Title of the invention: Mechanical gearbox with parallel shaft lines. Technical field
[0001] The present invention relates generally to gearboxes, and more particularly to a mechanical gearbox with parallel shaft lines, a vehicle comprising said gearbox and a method of mounting said gearbox. Technological background
[0002] A problem frequently encountered during the development of a gearbox is the misalignment of the bearings and gear teeth, i.e. their misalignment with respect to their operating planes.
[0003] In order to limit this bias, it is now known to apply a gear correction and / or to stiffen the gearbox casings.
[0004] Gear correction consists of adding a controlled correction during machining of gear teeth with a helical profile. However, this gear correction that can be applied during machining is limited by technical constraints, namely a maximum correction value applicable per tooth width.
[0005] Gearbox casings are generally stiffened by adding ribs and / or increasing their thickness. However, when engine torque is further increased, the stiffness provided by the ribs and / or increased thickness is no longer sufficient. Similarly, when gearbox casings are connected not only to an internal combustion engine but also to an electric motor, as is the case in hybrid vehicles, the presence of the electric motor causes additional flexing of the casings due to its weight, and the stiffness provided by the ribs and / or increased thickness is also no longer sufficient. It is then necessary to add further stiffness to the casings to absorb the additional flexing.
[0006] Furthermore, the application of a gear tooth correction and / or the stiffening of the gearbox casings in order to limit the slant requires the implementation of a long optimization process.
[0007] One object of the present invention is to improve existing gearboxes, and in particular to further increase the rigidity of the gearbox casings in order to further limit or even prevent the torsion of said casings and the associated slant, particularly when the engine torque is further increased or when the gearboxes speeds are linked not only to a combustion engine, but also to an electric motor, as is the case in hybrid vehicles. Summary of the invention
[0008] First object of the invention
[0009] To this end, a first object of the invention is a mechanical gearbox with parallel shaft lines, comprising: - a first casing and a second casing arranged opposite each other so as to delimit a space in which the shaft lines are housed, - at least one stiffening bar disposed in said space, the stiffening bar having a first end fixed to the first casing and a second end fixed to the second casing so as to join the first and second casings to each other.
[0010] The presence of such a stiffening bar can make it possible to stiffen the first and second gearbox casings, and therefore to limit or even prevent the torsion of said casings and the associated slanting.
[0011] For the reasons mentioned above, this is particularly advantageous when the engine torque is high or when the gearbox is connected on the one hand to a thermal engine and on the other hand to an electric motor, as is the case in hybrid vehicles.
[0012] The gearbox according to the first object of the invention may be simpler to manufacture compared to gearboxes of the prior art insofar as the use of a toothing correction and / or a ribbing of the casings and / or an increase in the thickness of the casings may become limited or even unnecessary.
[0013] When the gearbox according to the first object of the invention is integrated within a vehicle, it can further reduce noise and vibration, and thus improve the NVH (for "Noise, Vibration, and Harshness") of said vehicle.
[0014] Preferably, the stiffening bar extends parallel to the shaft lines.
[0015] The first housing and the second housing may each have a flat wall.
[0016] In the present description, "plane wall" means a wall forming in the same plane or in several adjacent parallel planes.
[0017] Said flat walls of the first and second housings are preferably parallel to each other.
[0018] The space in which the shaft lines are housed is preferably located between said flat walls of the first and second housings.
[0019] The stiffening bar can be fixed to the flat wall of the first housing by means of its first end and to the flat wall of the second housing by means of its second end so as to join the flat walls of the first and second crankcases to each other.
[0020] The stiffening bar is preferably perpendicular to the flat walls of the first and second housings.
[0021] The gearbox may include a shim washer interposed between the first end of the stiffening bar and the first casing, in particular between the first end of the stiffening bar and the flat wall of the first casing.
[0022] The shim washer is a calibrated washer whose role is to limit or even eliminate the play between the first end of the stiffening bar and the first housing, in particular between the first end of the stiffening bar and the flat wall of the first housing.
[0023] The shim washer is preferably a metal washer.
[0024] Its thickness can range from 0.8 mm ± 12.5 pm to 2.2 mm ± 12.5 pm, better from 1.0 mm ± 12.5 pm to 2.0 mm ± 12.5 pm, even better from 1.2 mm ± 12.5 pm to 1.8 mm ± 12.5 pm.
[0025] The gearbox may include fixing screws and the stiffening bar may include a tapped hole at each of its first and second ends.
[0026] The stiffening bar is preferably fixed to the first and second housings, in particular to the flat walls of the first and second housings, by means of the fixing screws which engage in each of the tapped holes of the stiffening bar.
[0027] The fixing screws are, for example, M8 hexagonal head screws.
[0028] The tapped holes are preferably oriented along the length of the bar stiffening.
[0029] The gearbox may include sealing washers interposed between the heads of the fixing screws and the first and second casings, in particular between the heads of the fixing screws and the flat walls of the first and second casings.
[0030] The sealing washers are designed to ensure a tight seal between the stiffening bar and the first and second crankcase halves, particularly the flat walls of the first and second crankcase halves. The space housing the shaft lines and the stiffening bar contains a lubricating oil, such as transmission oil. Therefore, it is necessary to seal this space to prevent any oil leakage.
[0031] The sealing washers are preferably metal washers with a polymer part in their center. This part ensures a watertight seal when the fixing screws are tightened.
[0032] The stiffening bar can be made of a steel-based or aluminum-based material, preferably an aluminum-based material. For example, the stiffening bar is made of an aluminum alloy, such as AlSi9Cu3(Fe).
[0033] Preferably, the stiffening bar is made of a material similar to that of the first and second housings.
[0034] The stiffening bar can have a diameter ranging from 10 mm to 30 mm, preferably from 15 mm to 25 mm. For example, the stiffening bar has a diameter of 20 mm.
[0035] The stiffening bar can have a length ranging from 65 mm to 215 mm, preferably from 90 mm to 190 mm, or even better from 100 mm to 180 mm. For example, the stiffening bar has a length of 113.5 mm or 164.5 mm.
[0036] The gearbox may include between one and five stiffening bars, preferably between one and three stiffening bars. For example, the gearbox includes three stiffening bars.
[0037] When the gearbox has several stiffening bars, these may or may not be identical. For example, they may be different in terms of length.
[0038] The gearbox according to the first object of the invention is particularly advantageous insofar as a number of parameters can be adjusted according to the architecture of the gearbox and according to the degree of rigidity desired at the level of the first and second casings, such as the number of stiffening bars, their positioning relative to the shaft lines, their diameter, their length, their material, etc.
[0039] The gearbox can be a gearbox for vehicles comprising a thermal engine and / or an electric motor.
[0040] In particular, the gearbox is a gearbox for vehicles comprising a thermal engine and an electric motor (also called hybrid vehicles).
[0041] In the case where the gearbox is a gearbox for hybrid vehicles, the first gearbox casing is preferably connected to the electric motor of the vehicle and the second gearbox casing is preferably connected to the internal combustion engine of the vehicle.
[0042] In the case where the gearbox is a gearbox for hybrid vehicles, the gearbox may have three parallel shaft lines, namely: - a primary line: this line has two coaxial shafts, namely a first primary shaft connected to the vehicle's internal combustion engine and a second primary shaft connected to the vehicle's electric motor; - a secondary line: this line connects the primary line and a differential line, the differential line transmitting the rotational torque to the vehicle's wheels; and - a coupling line: this line allows the rotational torque to be transmitted between the primary line and a rotor shaft of an additional electric motor of the vehicle.
[0043] In this case, the gearbox may include two or three stiffening bars.
[0044] When it comprises two stiffening bars, these are preferably located, on the one hand, around the coupling line, and on the other hand, around the secondary line. The two stiffening bars are preferably different. The stiffening bar located around the coupling line, for example, has a length of 164.5 mm and a diameter of 20 mm, while the stiffening bar located around the secondary line, for example, has a length of 113.5 mm and a diameter of 20 mm.
[0045] When it comprises three stiffening bars, one is located around the coupling line, one is located around the secondary line, and one is located around the primary line. The stiffening bars located around the primary and coupling lines are preferably identical. For example, they have a length of 164.5 mm and a diameter of 20 mm. The stiffening bar located around the secondary line is preferably shorter than those located around the primary and coupling lines. For example, it has a length of 113.5 mm and a diameter of 20 mm.
[0046] Second object of the invention
[0047] A second object of the invention is a vehicle comprising a gearbox according to the first object of the invention as defined above.
[0048] The vehicle may be a vehicle comprising a thermal engine and / or an electric motor.
[0049] In particular, the vehicle is a vehicle comprising a thermal engine and an electric motor (also called a hybrid vehicle).
[0050] In the case where the vehicle is a vehicle comprising a thermal engine and an electric motor (also called a hybrid vehicle), the electric motor of the vehicle is preferably connected to the first casing of the gearbox and the thermal engine of the vehicle is preferably connected to the second casing of the gearbox.
[0051] In the case where the vehicle is a vehicle comprising an internal combustion engine and an electric motor (also called a hybrid vehicle), the vehicle may also include an additional electric motor. The latter may have various functions, such as, for example, operating in generator mode, starting the vehicle's internal combustion engine (as do the starter-alternators of cars equipped with a Stop and Start system) and assisting the vehicle's internal combustion engine (boost function).
[0052] Third object of the invention
[0053] A third object of the invention is a method for assembling a gearbox according to the first object of the invention as defined above, comprising the steps of: - install at least one stiffening bar between the first and second crankcases, specifically between the flat walls of the first and second crankcases, - measure the clearance between the first end of the stiffening bar and the first housing, in particular between the first end of the stiffening bar and the flat wall of the first housing, - insert a shim washer between the first end of the stiffening bar and the first housing, specifically between the first end of the stiffening bar and the flat wall of the first housing, the stiffening washer having a thickness equal to the clearance measured in the previous step, - fix the stiffening bar to the first and second crankcases, in particular to the flat walls of the first and second crankcases, by tightening fixing screws engaged in tapped holes made in the stiffening bar at its first and second ends.
[0054] The assembly method according to the third object of the invention is simple to implement. Brief description of the figures
[0055] The following description, with reference to the accompanying drawings, given by way of non-limiting examples, will clearly explain what the invention consists of and how it can be implemented. In the accompanying figures:
[0056] [Fig-1] Fig. 1 represents a schematic and partial longitudinal section of a example of a gearbox according to the invention;
[0057] [Fig.2] The [Fig.2] represents a detailed view of the [Fig.1];
[0058] [Fig.3] Fig.3 represents, schematically and in perspective, an example of stiffening bar according to the invention;
[0059] [Fig.4] Fig.4 represents a schematic, perspective longitudinal section, of [Fig. 3]; and
[0060] [Fig. 5] [Fig. 5] represents an exploded and perspective view, schematic and partial, of another example of a gearbox according to the invention. Description of method(s) of implementation
[0061] An example of a mechanical gearbox 1 with parallel shaft lines 2 according to the invention is shown in [Fig.1].
[0062] The gearbox 1 comprises a first casing 3 and a second casing 4 arranged opposite each other so as to delimit a space 5 in which the shaft lines 2 are housed.
[0063] This space 5 contains a lubricating oil, such as a transmission oil, intended to lubricate the shaft lines 2.
[0064] The gearbox 1 further comprises two stiffening bars 6 arranged in said space 5.
[0065] Each stiffening bar 6 has a first end 6a fixed to the first housing 3 and a second end 6b fixed to the second housing 4 so as to join the first housing 3 and the second housing 4 to each other.
[0066] Each stiffening bar 6 extends parallel to the shaft lines 2.
[0067] The first housing 3 has a flat wall 3a and the second housing 4 has a flat wall 4a.
[0068] The term "plane wall" means a wall that lies in the same plane, as is the case for the plane wall 4a of the second housing 4, or a wall that lies in several adjacent parallel planes, as is the case for the plane wall 3a of the first housing 3.
[0069] The flat wall 3a of the first housing 3 and the flat wall 4a of the second housing 4 are parallel to each other.
[0070] The space 5 in which the shaft lines 2 are housed and in which the stiffening bars 6 are arranged is located between the flat wall 3a of the first housing 3 and the flat wall 4a of the second housing 4.
[0071] Each stiffening bar 6 is fixed to the flat wall 3a of the first housing 3 via its first end 6a and to the flat wall 4a of the second housing 4 via its second end 6b so as to join the flat wall 3a of the first housing 3 to the flat wall 4a of the second housing 4.
[0072] Each stiffening bar 6 extends perpendicularly to the flat walls 3a, 3b of the first and second housings 3, 4.
[0073] As illustrated in figures 1 to 4, a shim washer 7, preferably metallic, is interposed between the first end 6a of each of the stiffening bars 6 and the flat wall 3a of the first housing 3. The thickness of the shim washer 7 is generally between 1.2 mm ± 12.5 pm and 1.8 mm ± 12.5 pm.
[0074] This shim washer 7 has the role of limiting or even eliminating the play between the first end 6a of each of the stiffening bars 6 and the flat wall 3a of the first housing 3.
[0075] As illustrated in figures 1 to 4, each stiffening bar 6 has a tapped hole 8 at each of its ends 6a, 6b, the tapped hole 8 being oriented along the length of the stiffening bar 6.
[0076] Each stiffening bar 6 is fixed to the flat walls 3a, 4a of the first and second housings 3, 4 by means of fixing screws 9, which pass through the flat walls 3a, 4a at the level of bosses 10 present in the flat walls 3a, 4a, and which engage in the tapped holes 8.
[0077] The fixing screws 9 are, for example, M8 screws with a hexagonal head.
[0078] As illustrated in figures 1 to 4, sealing washers 11, preferably metallic with a polymer part in their center, are interposed between the heads 9a of the fixing screws 9 and the flat walls 3a, 4a.
[0079] These sealing washers 11 are intended to ensure a tight seal of the stiffening bar 6 to the flat walls 3a, 4a and thus prevent any leakage of lubricating oil outside the space 5 when tightening the fixing screws 9.
[0080] The stiffening bars 6 are made of a material similar to that of the first housing 3 and the second housing 4, for example an AlSi9Cu3(Fe) aluminium alloy.
[0081] The gearbox 1 may be a gearbox from a hybrid vehicle, i.e., a vehicle comprising a combustion engine and an electric motor. In this case, the first casing 3 is intended to be connected to the electric motor of the hybrid vehicle and the second casing 5 is intended to be connected to the combustion engine of the hybrid vehicle.
[0082] As illustrated in [Fig.5], the gearbox may include three stiffening bars 6.
[0083] The gearbox illustrated in [Fig.5] has 2 parallel shaft lines and a 20 shaft for the differential.
Claims
Claims
1. Mechanical gearbox (1) with parallel shaft lines (2), comprising: - a first casing (3) and a second casing (4) arranged opposite each other so as to delimit a space (5) in which the shaft lines (2) are housed, - at least one stiffening bar (6) arranged in said space (5), the stiffening bar (6) comprising a first end (6a) fixed to the first casing (3) and a second end (6b) fixed to the second casing (4) so as to join the first and second casings (3, 4) to each other, - a shim washer (7) interposed between the first end (6a) of the stiffening bar (6) and the first casing (3).
2. Gearbox (1) according to claim 1, the first casing (3) and the second casing (4) each having a flat wall (3a, 4a), said flat walls (3a, 4a) of the first and second casings (3, 4) being parallel to each other, the space (5) in which the shaft lines (2) are housed being located between said flat walls (3a, 4a) of the first and second casings (3, 4).
3. Gearbox (1) according to claim 2, the stiffening bar (6) being fixed to the flat wall (3a) of the first casing (3) via its first end (6a) and to the flat wall (4a) of the second casing (4) via its second end (6b) so as to join the flat walls (3a, 4a) of the first and second casings (3, 4) to each other.
4. Gearbox (1) according to claim 2 or 3, the stiffening bar (6) being perpendicular to the flat walls (3a, 4a) of the first and second casings (3, 4).
5. Gearbox (1) according to any one of the preceding claims, the shim washer (7) being interposed between the first end (6a) of the stiffening bar (6) and the flat wall (3a) of the first casing (3).
6. Gearbox (1) according to any one of the preceding claims, comprising fixing screws (9), the stiffening bar (6) comprising a tapped hole (8) at each of its first and second ends (6a, 6b) and being fixed to the first and second casings (3, 4), in particular to the flat walls (3a, 4a) of the first and second casings (3, 4), by means of the fixing screws (9) which engage in each of the tapped holes (8) of the stiffening bar (6).
7. Gearbox (1) according to any one of the preceding claims, comprising between one and five stiffening bars (6), preferably between one and three stiffening bars (6).
8. Gearbox (1) according to any one of the preceding claims, for vehicles comprising a heat engine and an electric motor, the first casing (3) of the gearbox (1) being in particular connected to the electric motor of the vehicle and the second casing (4) of the gearbox (1) being in particular connected to the heat engine of the vehicle.
9. Vehicle, in particular a vehicle comprising a heat engine and an electric motor, comprising a gearbox (1) according to any one of the preceding claims.
10. A method of mounting a gearbox (1) according to any one of claims 1 to 8, comprising the steps of: - mounting at least one stiffening bar (6) between the first and second casings (3, 4), in particular between the flat walls (3a, 4a) of the first and second casings (3, 4), - measuring the clearance between the first end (6a) of the stiffening bar (6) and the first casing (3), in particular between the first end (6a) of the stiffening bar (6) and the flat wall (3a) of the first casing (3), - interposing a shim washer (7) between the first end (6a) of the stiffening bar (6) and the first casing (3), in particular between the first end (6a) of the stiffening bar (6) and the flat wall (3a) of the first casing (3), the shim washer (7) having a thickness equal to the clearance measured in the previous step, - fixing the stiffening bar (6) to the first and second casings (3, 4),in particular to the flat walls (3a, 4a) of the first and second casings (3, 4), by tightening fixing screws (9) engaged in tapped holes (8) made in the stiffening bar (6) at its first and second ends (6a, 6b).,