Magnetic assembly and sump plug comprising such a magnetic assembly

Abstract

The invention relates to a magnetic assembly (10) for a transmission system, comprising: - an axial stack of magnets (13) arranged along a main axis (X), each of the magnets (13) comprising a thickness (Ep) and a polarity oriented according to the main axis, each magnet being installed in relation to the next magnet in such a way that the same magnetic poles (N, S) face each other; - a longitudinal support (15) which holds the axial stack of magnets in position with a first axial stop (11) bearing on a first end magnet (13a) and a second axial stop (12) bearing on a second end magnet (13b); wherein the axial distance (D1) separating the first axial stop (11) and the second axial stop (12) is greater than the sum of the thicknesses (Ep) of the magnets (13), and the magnets (13) take up their positions in relation to one another at points where the magnetic fields are in equilibrium.

Description

Description Title of the invention: magnetic assembly and crankcase cap comprising such a magnetic assembly technical field

[0001] The invention relates to the field of magnetic assemblies for transmission systems and the field of transmission systems for electric or hybrid vehicles. More particularly, the invention relates to two components of this transmission system that incorporate a magnetic assembly: the crankcase plug and the hydraulic device arranged to supply oil to the transmission system.

[0002] The invention also relates to the internal lubrication, for example by splashing or under pressure, of the components of a transmission system, and in particular of a speed reduction mechanism.

[0003] To lubricate the components of a transmission system, particularly the rotating bearings and gears of the speed reduction mechanism, it is common practice to place the moving components inside a housing containing oil, but without fully immersing the moving components, such as a drive shaft supporting gears, in the oil bath. The movement of the transmission mechanism then uses splashing to circulate the oil and distribute it throughout the entire internal volume of the housing, ensuring the desired lubrication of the entire mechanism, including the non-immersed parts.

[0004] The rotation of the transmission shafts in the speed reduction mechanism will cause wear and the emission of metallic particles from friction between the gears. These metallic particles pose a risk to the guide bearings, and the emission of particles through the meshing of the transmission shafts contaminates the lubricating oil.

[0005] To combat this oil pollution, it is known to install a magnet immersed in the oil bath within the crankcase, which will be responsible for collecting metallic particles in the speed reduction mechanism.

[0006] A simple magnet can have a large magnetic exchange surface but with only one magnetic field. Its effectiveness will be limited. The installation of such a magnet within the speed reduction mechanism must be done in a so-called "quiet" area in terms of oil flow to prevent the risk of metallic particles escaping.

[0007] A transmission system such as the one described in the Korean utility model KR19990030635 U includes an oil pan drain plug equipped with a permanent magnet, which protects the engine by preventing impurities such as iron dust mixed with the engine oil from entering the engine. The drain plug includes, in particular, a shaft-shaped permanent magnet press-fitted into a gripping base. This type of drain plug is unsatisfactory because the magnetic exchange surface with the oil is limited.

[0008] There is also a magnetic assembly made from small magnets glued together, which have a small magnetic exchange surface but multiple magnetic fields. Gluing the magnets together to form a magnetic plate is a complex assembly process.

[0009] The objective of the invention is to increase the magnetic exchange surface area of ​​the magnetic assembly immersed in the oil bath. In particular, in the field of transmission systems for electric or hybrid vehicles, it is not possible to drain the oil contained in the casing, so the magnetic assembly must collect metallic particles throughout the life of the speed reduction mechanism. Description of the invention

[0010] The invention aims to overcome the drawbacks of the prior art and to propose a magnetic assembly combining an increased magnetic exchange surface and a simplified assembly.

[0011] To this end, according to a first aspect of the invention, a magnetic assembly for a transmission system is proposed, comprising: - an axial stack of magnets along a principal axis, each of the magnets comprising a thickness and a polarity oriented along the principal axis defined by a North magnetic pole (N) and a South magnetic pole (S), each magnet being installed relative to the next magnet by associating the same North or South magnetic poles opposite each other; - a longitudinal support which holds in position the axial stack of magnets with a first axial stop bearing on a first end magnet and a second axial stop bearing on a second end magnet; in which the axial distance separating the first axial stop and the second axial stop is greater than the sum of the thicknesses of the magnets and the positioning of the magnets relative to each other is done by equilibrium of the magnetic fields.

[0012] The arrangement of the magnets relative to each other, with their corresponding North or South magnetic poles facing each other, creates a free space between each magnet. Metallic particles can then penetrate this free space and adhere to the magnets, as illustrated in Figure 2. This increases the overall magnetic exchange surface area.

[0013] Positioning the magnets relative to each other, based on the balance of their magnetic fields, allows for multiple fields with a large magnetic exchange surface. Assembling the magnets is also simplified. The magnets are positioned close enough to create a repulsive effect generated by the magnetic field. The magnets repel each other due to their alignment by matching their magnetic poles.

[0014] Preferably, each magnet is subjected to the effect of the magnetic field of the adjacent magnet.

[0015] Because many metallic particles are now trapped between the magnets, they will no longer be carried along by the oil flow within the speed reduction mechanism. It is no longer necessary to create a so-called "quiet zone" within the speed reduction mechanism to position the magnet, as is done in current transmission systems.

[0016] According to one aspect of the invention, the magnets are spaced apart from each other along the main axis by an axial clearance greater than 0.5 mm, for example greater than 1 mm.

[0017] According to one aspect of the invention, the magnets are spaced apart from each other along the main axis by a gap of between 0.5 mm and 5 mm. In this way, the axial gap separating each magnet is less than the distance beyond which the magnetic field of the adjacent magnet no longer has an effect.

[0018] According to one aspect of the invention, the axial distance separating the first axial stop and the second axial stop is less than twice the sum of the thicknesses of the magnets.

[0019] Advantageously, the magnets are of the permanent type. For example, the permanent magnet is made of ferrite.

[0020] According to one aspect of the invention, the first axial stop and / or the second axial stop is attached to the longitudinal support.

[0021] According to one aspect of the invention, the first axial stop or the second axial stop is formed from material with the longitudinal support.

[0022] According to one aspect of the invention, each magnet includes a central orifice and the longitudinal support passes through the central orifice of each of the magnets.

[0023] According to one aspect of the invention, the longitudinal support surrounds each of the magnets.

[0024] The invention may have one or more of the features described below, either combined or taken independently of each other. - the axial stack of magnets includes between two and ten magnets; - the magnet has a circular shape; - the magnet has a ring shape; - the magnet has a bar shape; - the first axial stop is a fixing screw; - the first axial stop is a shoulder; - the first axial stop is a rivet; - the first axial stop is a stop ring; - the second axial stop is a fixing screw; - the second axial stop is a shoulder; - the second axial stop is a rivet; - the second axial stop is a retaining ring.

[0025] According to a second aspect, the invention also relates to a crankcase plug for a transmission system comprising a gripping base, a body threaded along a secondary axis backed against the gripping base, and a magnetic assembly, reproducing all or part of the characteristics mentioned above, disposed on the end of the threaded body, the secondary axis and the main axis of the magnetic assembly are concentric.

[0026] A housing plug that directly supports the magnetic assembly allows for a compact fit within the gearbox housing. This makes it easy to check for oil contamination within the transmission system.

[0027] Preferably, the outside diameter of the threaded body is greater than the outside diameter of the magnetic assembly, for example greater than the outside diameter of the first end magnet.

[0028] According to a third aspect, the invention also relates to a hydraulic device for a transmission system comprising at least one tube arranged to distribute a fluid hydraulic and a magnetic assembly, incorporating all or part of the characteristics mentioned above, in which each magnet includes a central orifice, the longitudinal support of the magnetic assembly being inserted inside the tube.

[0029] Thanks to the central opening, the oil passes directly through the magnetic assembly.

[0030] The hydraulic device can be, for example, a hydraulic pump or a hollow transmission shaft.

[0031] Preferably, the longitudinal support is cylindrical in shape.

[0032] The cylindrical shape allows the magnetic assembly to be easily housed within a hydraulic pump or a hollow transmission shaft.

[0033] According to a fourth aspect, the invention also relates to a transmission system for electric or hybrid vehicles comprising: - a crankcase containing an oil bath; - a mobile transmission shaft rotating relative to the casing around a first axis of rotation; - a guide bearing supporting the transmission shaft relative to the casing, the guide bearing being inserted into a cylindrical housing provided in the casing; - a crankcase plug incorporating all or part of the characteristics mentioned above, in which the magnetic assembly is immersed in the oil bath.

[0034] A crankcase plug that directly supports the magnetic assembly allows for a compact fit within the transmission system's housing. This makes it easy to check for oil contamination within the transmission system.

[0035] According to one variant of the invention, the magnetic assembly can be separate from the crankcase plug. Brief description of the figures

[0036] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings. [fig.1] Figure 1 represents a transmission system and a crankcase plug comprising a magnetic assembly according to a first embodiment of the invention. [fig.2] Figure 2 represents a used crankcase plug according to the first embodiment of the invention of figure 1. [fig.3] Figure 3 represents a transmission system comprising a magnetic assembly according to a second embodiment of the invention. [fig.4] Figure 4 represents a transmission system comprising a magnetic assembly according to a third embodiment of the invention. [fig.5] Figure 5 represents a hydraulic device comprising a magnetic assembly according to a fourth embodiment of the invention. [fig.6] Figure 6 represents a hydraulic device comprising a magnetic assembly according to a fifth embodiment of the invention. Description of the implementation methods

[0037] Figure 1 illustrates a transmission system 1 for an electric or hybrid vehicle, comprising an electric machine (not shown) and a speed reduction mechanism 2 kinematically linked to this electric machine. The speed reduction mechanism 2 transmits the torque from the electric machine to the wheels of the electric or hybrid vehicle.

[0038] The electric machine is held on a housing 40a, 40b of the transmission system 1. The housing generally consists of a main housing 40a supporting the electric machine and a closing housing 40b bearing against the main housing 40a at a joint 48, to seal a cavity defined by the main housing 40a and the closing housing 40b. The cavity notably receives a transmission shaft 5 guided in rotation relative to the housing by means of guide bearings 100a, 100b. The transmission shaft 5 includes at least one pinion contributing to the reduction of the electric machine's rotational speed.

[0039] To lubricate the various components of the transmission system 1, the housing 40a, 40b contains lubricating fluid, for example, oil. The guide bearings 100a, 100b and the transmission shaft pinion 5 are partially immersed in the oil. The operation of the speed reduction device 2 then agitates the oil by splashing it throughout the entire internal volume of the housing, ensuring the desired lubrication of the entire system, including the non-immersed parts.

[0040] For the remainder of this presentation, we define a reference operational position of transmission system 1 as the three-dimensional orientation in which transmission system 1 is installed in a horizontal vehicle. In this position In the reference operational position, the transmission shaft 5 is located above the lubricating oil level. In the remainder of this description, unless otherwise stated, the invention will be described in this reference operational position.

[0041] The two guide bearings 100a and 100b require continuous lubrication with lubricating oil, as indicated by the white arrows in Figure 1. To lubricate the first guide bearing 100a, which is inserted into the main housing 40a, an oil supply channel opens into the housing of guide bearing 100a. The oil is then routed to the second guide bearing 100b through a through hole 6 located in the center of the hollow transmission shaft 5.

[0042] After passing through the second guide bearing 100b, the oil falls into an oil bath 80. Metallic particles may be transported by the oil during its passage through the speed reduction mechanism 2.

[0043] According to the invention, a crankcase plug 20 comprising a gripping base 21 and a threaded body 22 along a secondary axis X2 backed against the gripping base is immersed in the oil bath 80. The crankcase plug 20 can be gripped by hand or with a tool.

[0044] To collect the metallic particles present within the oil bath 80, a magnetic assembly 10 is attached to the threaded body 22 of the crankcase plug 20.

[0045] The magnetic set 10 includes: - an axial stack of magnets 13 along a principal axis X, each of the magnets 13 comprising a thickness Ep and a polarity oriented along the principal axis, each magnet being installed relative to the following magnet by associating the same magnetic poles N, S opposite each other; - a longitudinal support 15 which holds in position the axial stack of magnets 13 with a first axial stop 11 bearing on a first end magnet 13a and a second axial stop 12 bearing on a second end magnet 13b.

[0046] Thus, the South magnetic pole of a first magnet is positioned opposite the South magnetic pole of a second adjacent magnet.

[0047] In the magnetic assembly 10, the axial distance D1 separating the first axial stop 11 and the second axial stop 12 is greater than the sum of the thicknesses Ep of the magnets 13 and the positioning of the magnets 13 with respect to each other is done by equilibrium of the magnetic fields.

[0048] Each magnet 13 is subjected to the effect of the magnetic field of the adjacent magnet.

[0049] For space reasons, the magnetic assembly 10 is positioned on the end of the threaded body 22, and the secondary axis X2 and the main axis X of the magnetic assembly are concentric. The outside diameter D of the threaded body 22 is larger than the outside diameter d of the magnetic assembly 10, for example, larger than the outside diameter of the first end magnet 13a.

[0050] The longitudinal support 15 is a rod made of material with the threaded body 22. Each magnet 13 includes a central orifice 13c and the longitudinal support 15 passes through the central orifice 13c of each of the magnets.

[0051] The magnets 13 are permanent type and made, for example, of ferrite. The axial stack of magnets 13 comprises between six magnets.

[0052] Each magnet 13 has a ring shape.

[0053] The magnets 13 are spaced apart from each other along the main axis X by an axial clearance J greater than 0.5 mm, in this example the axial clearance J is on the order of 1 mm.

[0054] Figure 2 shows that the metallic particles infiltrate the available free space between each magnet 13 and remain stuck to the magnets after unscrewing the housing cap 20 of the housing 40a, 40b of the transmission system 1.

[0055] In this first embodiment of the invention, the second axial stop 12 is attached to the longitudinal support 15. The second axial stop 12 is a fixing screw.

[0056] The first axial stop 11 is made of material with the longitudinal support 15. The first axial stop 11 is a shoulder formed by the threaded body 22.

[0057] We will now describe, with reference to figure 3, a transmission system 1 according to a second embodiment of the invention which differs from the first embodiment in that the magnetic assembly 10 is separate from the housing plug 20.

[0058] The magnetic assembly 10 is fixed directly onto the main housing 40a of the transmission system 1 while the housing plug 20 is fixed onto the closing housing 40b.

[0059] The magnetic assembly 10 is screwed onto the main housing 40a.

[0060] The main axis X of the magnetic assembly 10 is concentric with the secondary axis X2 of the crankcase plug 20. In this way, by unscrewing the crankcase plug 20, it is possible to directly visualize the level of contamination of the oil bath.

[0061] To facilitate disassembly of the magnetic assembly, the outside diameter D of the threaded body 22 is greater than the outside diameter d of the magnetic assembly 10.

[0062] We will now describe, with reference to figure 4, a transmission system 1 according to a third embodiment of the invention which differs from the first embodiment in that each magnet 13 has a bar shape.

[0063] The magnetic set 10 includes: - an axial stack of magnets 13 along a principal axis X, each of the bar-shaped magnets 13 comprising a thickness and a polarity oriented along the principal axis X, each magnet being installed relative to the next magnet by associating the same magnetic poles N, S opposite each other; - a longitudinal support 15 which holds in position the axial stack of magnets 13.

[0064] The positioning of the bar-shaped magnets 13 relative to each other is achieved by balancing their magnetic fields. The longitudinal support 15 comprises two longitudinal rails, each supporting one of the magnets.

[0065] We will now describe, with reference to figure 5, a transmission system 1 according to a fourth embodiment of the invention which differs from the first embodiment in that the magnetic assembly 10 is arranged within a hydraulic device 30 for transmission system 1.

[0066] The hydraulic device 30 comprises a tube 31 arranged to distribute a hydraulic fluid (represented by the white arrows) and the magnetic assembly 10 in which each magnet 13 has a central orifice 13c. The oil passes directly through the magnetic assembly 10.

[0067] Each magnet 13 has a ring shape.

[0068] The magnetic set 10 includes: - an axial stack of magnets 13 along a principal axis X, each of the magnets 13 comprising a thickness Ep and a polarity oriented along the principal axis X, each magnet being installed relative to the following magnet by associating the same magnetic poles N, S opposite each other; - a longitudinal support 15 which holds in position the axial stack of magnets 13 with a first axial stop 11 bearing on a first end magnet 13a and a second axial stop 12 bearing on a second end magnet 13b.

[0069] In the magnetic assembly 10, the axial distance D1 separating the first axial stop 11 and the second axial stop 12 is greater than the sum of the thicknesses Ep magnets 13 and the positioning of the magnets 13 relative to each other is done by balancing the magnetic fields.

[0070] The second axial stop 12 is a shoulder formed in the longitudinal support 15.

[0071] The first axial stop 11 is a stop ring.

[0072] The longitudinal support 15 is cylindrical in shape and surrounds each of the magnets 13.

[0073] The longitudinal support 15 of the magnetic assembly 10 is inserted inside the tube 31.

[0074] Hydraulic device 30 is, for example, a hydraulic pump.

[0075] We will now describe, with reference to figure 6, a transmission system 1 according to a fifth embodiment of the invention which differs from the first embodiment in that the magnetic assembly 10 is arranged within a hydraulic device 30 which is here a hollow transmission shaft 5.

[0076] The hollow transmission shaft 5 includes a through hole 6 in the center of the shaft. The through hole 6 is a tube arranged to distribute a hydraulic fluid (represented by the white arrows).

[0077] The magnetic assembly 10 is inserted into the through hole 6.

[0078] In this fifth embodiment, each magnet 13 has an annular shape and includes a central orifice 13c. The oil passes directly through the magnetic assembly 10.

[0079] The magnetic set 10 includes: - an axial stack of magnets 13 along a principal axis X, each of the magnets 13 comprising a thickness and a polarity oriented along the principal axis X, each magnet being installed relative to the following magnet by associating the same magnetic poles N, S opposite each other; - a longitudinal support 15 corresponding to the through hole 6 which holds in position the axial stack of magnets 13.

[0080] The second axial stop 12 is a retaining ring and the first axial stop 11 is a shoulder formed in the longitudinal support 15

[0081] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0082] In claims, any reference sign in parentheses should not be interpreted as a limitation of the claim.

Claims

Demands 1. Magnetic assembly (10) for transmission system, comprising: - an axial stack of magnets (13) along a principal axis (X), each of the magnets (13) comprising a thickness (Ep) and a polarity oriented along the principal axis defined by a north magnetic pole (N) and a south magnetic pole (S), each magnet being installed relative to the following magnet by associating the same North or South magnetic poles (N, S) opposite each other; - a longitudinal support (15) which holds in position the axial stack of magnets with a first axial stop (11) bearing on a first end magnet (13a) and a second axial stop (12) bearing on a second end magnet (13b); in which the axial distance (D1) separating the first axial stop (11) and the second axial stop (12) is greater than the sum of the thicknesses (Ep) of the magnets (13) and the positioning of the magnets (13) relative to each other is done by equilibrium of the magnetic fields.

2. Magnetic assembly (10) according to claim 1, in which the magnets (13) are spaced from each other along the main axis by an axial clearance (J) greater than 1 mm.

3. Magnetic assembly (10) according to claim 1 or 2, wherein the first axial stop (11) and / or the second axial stop (12) is reported on the longitudinal support (15).

4. Magnetic assembly (10) according to any one of claims 1 to 3, wherein the first axial stop (11) or the second axial stop (12) is made of material with the longitudinal support (15).

5. Magnetic assembly (10) according to any one of the preceding claims, in which each magnet (13) comprises a central orifice (13c) and the longitudinal support (15) passes through the central orifice of each of the magnets.

6. Magnetic assembly (10) according to any one of claims 1 to 4, in which the longitudinal support (15) surrounds each of the magnets (13).

7. Crankcase plug (20) for transmission system comprising a gripping base (21), a threaded body (22) along a secondary axis (X2) abutting the base gripping, and a magnetic assembly (10) according to one of the preceding claims disposed on the end of the threaded body (22), the secondary axis (X2) and the main axis (X) of the magnetic assembly are concentric.

8. Crankcase plug (20) according to the preceding claim, wherein the outside diameter (D) of the threaded body (22) is greater than the outside diameter (d) of the magnetic assembly (10), for example greater than the outside diameter of the first end magnet (13a).

9. Hydraulic device (30) for transmission system comprising at least one tube (31) arranged to distribute a hydraulic fluid and a magnetic assembly (10) according to claim 6 in which each magnet (13) includes a central orifice (13c), the longitudinal support (15) of the magnetic assembly being inserted inside the tube (31).

10. Transmission system (1) for electric or hybrid vehicles comprising: - a casing (40a, 40b) containing an oil bath (80); - a transmission shaft (5) movable in rotation relative to the casing around a first axis of rotation (Y); - a guide bearing (100a, 100b) supporting the transmission shaft relative to the housing, the guide bearing being inserted in a cylindrical housing (41) provided in the housing; - a crankcase plug (20) according to claim 7 or 8; in which the magnetic assembly (10) is immersed in the oil bath.

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