WO2022263433A1

WO2022263433A1 - Actuator for a motor vehicle transmission system

Info

Publication number: WO2022263433A1
Application number: PCT/EP2022/066147
Authority: WO
Inventors: Sylvain FAVELIER; Pierre Colomb; Thierry Lanoe
Original assignee: Valeo Systemes De Controle Moteur
Priority date: 2021-06-18
Filing date: 2022-06-14
Publication date: 2022-12-22
Also published as: FR3124123A1

Abstract

The present invention provides an actuator (1) for a transmission system, said actuator (1) comprising: a casing (2) defining an annular space having axis X; an annular piston (3) for transmitting an actuating force to a coupling device, the piston (3) being placed coaxially to the X-axis and being mounted so as to be capable of moving along the X-axis between a retracted position (R) and a deployed position (D); an annular coil (5) comprising a conductor winding, the coil (5) being encapsulated by a polymer coating (6); the actuator (1) being characterised in that at least one fluid guiding means (12, 14a, 14b, 24) is provided between the casing (2) and the coating of the coil (5).

Description

Title of the invention: Actuator for a motor vehicle transmission system

[1] The invention relates to an actuator for a motor vehicle transmission system.

[2] The invention relates more particularly to an electromagnetic actuator which is intended to be housed inside a transmission casing of the transmission chain by being linked to a coupling device.

[3] Document US 20170159726 A1 discloses an electromagnetic actuator for actuating a coupling device fitted to a differential system. The coupling device has an uncoupled state in which the differential is free to distribute torque from a motor to two wheel shafts of an axle of the vehicle and a coupled state which deactivates the "differential" function so that the two axle shafts cannot rotate at different speeds. The electromagnetic actuator comprises a casing which is intended to be fixed in a transmission casing in which the differential system is also housed. Furthermore, the electromagnetic actuator comprises a housing having an annular space in which are housed an overmolded coil and a piston mounted to move between a retracted position and an extended position. The various movements of the piston between its retracted position, its extended position and vice versa cause noises or shocks in contact with metal parts. Noise is particularly undesirable for the comfort of vehicle passengers and shocks can cause vibrations of the actuator and ultimately prevent proper operation or even destruction of the actuator. In addition, in this actuator, the moving elements are not lubricated, so that heating of the elements may occur.

[4] The object of the present invention is to improve current solutions, in particular by proposing an actuator with a simple architecture and making it possible to lubricate the inside of the actuator while making it possible to reduce the noise and shocks associated with the movements of the piston between its retracted position, its deployed position and vice versa. [5] More particularly, the invention relates to an actuator for a transmission system comprising a housing defining an annular space of axis X, an annular piston intended to transmit an actuation force to a coupling device, the piston being arranged coaxially to the X axis and being mounted axially movable along the X axis between a retracted position and an extended position, an annular coil comprising a winding of conductive wire, the coil being encapsulated by a coating, at least one means guiding a fluid is provided between the housing and the coating of the coil.

[6] Thus, overheating of the elements constituting the actuator will be avoided, the elements will be lubricated and the noise or shocks of the piston during its movements will be reduced.

[7] According to the invention, the coating of the annular coil is made of polymer material, for example epoxy resin, polyurethane or polyamide. In other words, the coil is overmolded. Advantageously, the coating forms an annular radial extension defining an end stop of the piston stroke.

[8] According to a feature of the invention, the coil is housed in the annular space of the housing.

[9] According to another feature of the invention, the piston is housed in the annular space of the housing. Alternatively, the piston may be located outside the housing.

[10] According to a characteristic of the invention, the piston is located radially inside the coil. Alternatively, the piston can be located radially outside the spool.

[11] Advantageously, the radial extension defines an end stop for the piston when it is in the retracted position. Alternatively, the radial extension defines an end stop of the piston when it is in the deployed position.

[12] According to the invention, the housing, seen in section, is "U" shaped and is made of a single material, preferably a magnetic material, for example steel. By a single material is meant the fact that the housing is in one piece. The use of a housing made of a single material makes it possible to simplify the design and manufacture of the actuator. [13] Alternatively, the housing, seen in section, is "U" shaped consisting of two assembled "L" shaped parts, the two parts being preferably made of a magnetic material, for example steel. The two “L” shaped parts are for example assembled by a crimping, rolling or fitting operation.

[14] According to a feature of the invention, the housing comprises a radially inner skirt, a bottom surface and a radially outer skirt. If the piston is located radially inside the spool then the piston guiding surface is the radially inner skirt. If the piston is located radially outboard of the spool then the piston guiding surface is the radially outer skirt.

[15] The guide surface of the piston can be coated with a thermochemical treatment in order to harden the surface of the part in sliding contact with the piston and thus facilitate sliding.

[16] Preferably, the surfaces of the case can be machined in order to obtain a good surface finish and can also be associated with a surface treatment, for example of the "DLC" type which means in English "diamond-like carbon". or carbon in the form of amorphous diamond in French, “TiN” which means titanium nitride or “MOS2” which means molybdenum disulphide or nitride. These treatments make it possible to optimize the tribological performance of the surfaces of the case.

[17] According to the invention, the means for guiding a fluid is at least one annular groove located on the bottom surface of the housing opposite a surface of the coating of the coil.

[18] According to an additional characteristic of the invention, the means for guiding a fluid is at least one groove located on a surface of the coating of the coil facing the bottom surface of the housing.

[19] According to the invention, the means for guiding a fluid is at least one groove located on the outer surface of the coating of the coil facing the radially outer skirt of the housing. [20] According to a characteristic of the invention, the means for guiding a fluid is at least one groove located on the internal surface of the coating of the coil facing the radially internal skirt of the housing.

[21] According to a feature of the invention, the means for guiding a fluid is at least one groove located on the surface of the radial extension facing the piston

[22] According to the invention, the housing comprises an opening located in the radially outer skirt, this opening allows the passage of fluid from the outside to the inside of the housing as well as the passage of an electrical connector of the coil.

[23] According to another characteristic of the invention, the housing is made of a material whose carbon content is less than 0.2%, for example steel. This steel is thus called low carbon steel. This characteristic makes it possible to reduce the mass of the actuator.

[24] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given for illustrative purposes only. and non-limiting, with reference to the accompanying drawings:

[25] [Figure 1] illustrates an actuator according to the invention in front view;

[26] [Figure 2] illustrates the actuator of Figure 1 in section along the axis A-A;

[27] [Figure 3a] illustrates an annular coil of the actuator according to a first embodiment;

[28] [Figure 3b] illustrates an annular coil of the actuator according to a second embodiment;

[29] [Figure 4] illustrates the annular coil of the actuator in rear face view;

[30] [Figure 5] illustrates an alternative embodiment of the actuator;

[31] [Figure 6] illustrates a perspective view of the actuator housing according to the variant of Figure 5.

[32] In relation to Figure 1, an actuator 1 is described according to one embodiment of the invention which is adapted to be housed in a transmission casing. The transmission casing can be made up of any casing of the transmission chain of a vehicle, in particular a differential casing. The actuator 1 is here an electromagnetic actuator capable of being linked to a coupling device (not shown) of a motor vehicle transmission. It comprises a casing 2 which is intended to be fixed to a transmission casing (not shown). In this housing 2 are arranged an annular coil 5 as well as an annular piston 3 which will be described in relation to the following figures.

[33] The actuator 1 includes an electrical connector 10 which is intended for connecting the coil 5 to a control device which is positioned outside the casing. The electrical connector 10 is connected to the coil 5 by at least one flexible cable and makes it possible to supply this coil 5 electrically.

[34] Figure 2 makes it possible to better visualize the constituent elements of the actuator 1. The actuator 1 thus comprises a housing 2 defining an annular space of axis X in which are housed the annular piston 3 intended to transmit a force of actuation to a coupling device and the annular coil 5. The piston 3 is arranged coaxially to the axis X and is mounted axially movable along the axis X between a retracted position R and an extended position D. the piston 3 is located radially inside coil 5.

[35] In the embodiment of this figure 2, the housing 2 is shaped like a

"U" and is made of a single material, preferably magnetic steel. This steel has a carbon content that is less than 0.2%. The housing 2 comprises a radially inner skirt 21 serving as a guide surface for the piston 3, a bottom surface 22 and a radially outer skirt 23. On the bottom surface 22 of the outer side of the housing 2 are protrusions 26 distributed angularly around of the X axis and allowing contact with an element of the transmission, for example a bearing. In the present embodiment, four protuberances 26 are present.

[36] The annular coil 5 consists of a conductive wire winding and is encapsulated in a sealed manner by a coating 6 of polymeric material, for example epoxy resin, polyurethane or polyamide. The coating 6 forms an annular radial extension 7 defining an end stop of the piston 3 when it is in the retracted position R. The radial extension 7 is located axially along the X axis on the side of the bottom surface 22 of the box 2. In other words the radial extension 7 is in contact with the bottom surface 22 of the box 2.

[37] The piston 3 is movably mounted in a housing 11 defined between the coil 5 and the inner skirt 21 of the housing 2. The radial extension 7 of the coil 5 extends inside this housing 11. The radial extension 7 extends radially in the direction of the X axis.

[38] The annular space of the housing 2 is closed by a magnetic cover 8, the magnetic cover 8 defines an end stop of the piston 3 when the piston 3 is in the deployed position D. The magnetic cover 8 is fixed to the housing 2 via tabs 9 belonging to the outer skirt 23 of housing 2. These tabs 9 are folded down in the direction of the magnetic cover 8 during assembly. The piston 3 has a shoulder intended to come into abutment against a shoulder of the magnetic cover 8 when the piston 3 is in the deployed position D.

[39] The piston 3 is made of ferromagnetic material, such as iron or steel for example. The piston 3 further comprises a non-magnetic end piece 4, also of annular shape, which is fixed to the piston 3 and by which the actuating force is transmitted to the coupling device. Non-magnetic means a material having an absence of magnetic property. The non-magnetic tip 4 of the piston 3 thus makes it possible to avoid undesirable leaks of magnetic flux towards the other components of the coupling device. The non-magnetic tip 4 is for example made of bronze or aluminum.

[40] When the actuator 1 is located in a differential housing, as in the present invention, this actuator 1 is partially immersed in a hydraulic fluid, such as oil. This oil makes it possible to lubricate the elements in contact in the differential casing but also to limit overheating. In the case of the present invention, it is particularly useful to take advantage of this humid environment in order to lubricate and cool the constituent elements of the actuator 1. For this purpose, the housing 2 comprises an opening 25 located in the radially outer skirt 23, this opening 25 allows the passage of fluid from the outside to the inside of the housing 2. This opening also allows the passage of the electrical connector 10 of the coil 5. In order to conduct the fluid inside the housing 2, there is at least one means for guiding a fluid 12a, 12b, 14a, 14b, 24 provided between housing 2 and coating 6 of coil 5.

[41] Figure 3a shows a first means for guiding this fluid. Indeed, the internal surface 51 of the coating 6 of the coil 5 is provided with grooves 12a allowing the guiding of a fluid between the coil and the piston 3. These grooves 12a are distributed angularly and at regular intervals over the entire periphery of the internal surface 51 of the coil 5. These grooves 12a extend axially along the axis X. The surface 71 of the radial extension 7 facing the piston 3 is also provided with grooves 12b allowing the guiding of the fluid. These grooves 12b are distributed angularly and at regular intervals over the entire periphery of the radial extension 7 of the coil 5 facing the piston 3. These grooves 12b extend perpendicular to the grooves 12a. The grooves 12a and 12b thus form a continuous groove. The grooves 12b have a direction which converges towards a point located on the X axis.

[42] The radial extension 7 of the coil 5 comprises at least one axial slot 11. This axial slot 11 separates two sections 13. According to the embodiment shown in Figure 4, there are three sections 13 separated by three axial slots 11 This axial slot 11 allows the reel 5 to be indexed on a tool in order to facilitate the operation of winding the conductive wire.

[43] The embodiment of the coil 5 visible in Figure 3b is an alternative embodiment of the embodiment visible in Figure 3a. The identical characteristics between the two modes bear the same numerical references. Unlike Figure 3a, Figure 3b shows the outer surface 52 of the coating 6 of the coil 5 provided with grooves 14a. These grooves 14a are face to face with the radially outer skirt 23 of the housing 2 and allow the flow of fluid between the housing 2 and the coil 5. These grooves 14a are distributed angularly and at regular intervals over the entire periphery of the outer surface 52 of the coil 5. These grooves 14a extend axially along the axis X.

[44] Of course, it is also possible while remaining within the scope of the present invention to provide a coil 5 having only grooves on the external surface 52 of the coating 6 of the coil 5 without having grooves on the internal surface 51 nor on the radial extension 7.

[45] The grooves 12a, 12b, 14a, 14b also have the function of contributing to the reinforcement of the mechanical strength of the overmolding of the coil 5.

[46] Figure 4 shows the surface 53 of the coating 6 of the coil 5 facing the bottom surface 22 of the housing 2. This surface 53 has grooves 14b allowing guidance of the fluid between the coating 6 of the coil 5 and the bottom surface 22 of the housing 2. These grooves 14b extend parallel to an axis Y orthogonal to the axis X.

[47] Figure 5 shows an alternative embodiment of the housing 2. In this embodiment, the bottom surface 22 of the housing 2 comprises an annular groove 24 vis-à-vis the surface 53 of the coating 6 of the coil 5. A single groove 24 is shown but it is quite possible to make several concentric grooves 24.

[48] Figure 6 shows through a perspective view this groove 24 disposed on the bottom surface 22 of the housing 2. This groove 24 is concentric with the X axis and is radially close to the radially inner skirt 21 of the casing 2. At least one opening 27 is provided in this groove 24 in order to allow the fluid to circulate between the exterior and the interior of casing 2 and vice versa. In the present case, three openings 27 are provided in the groove 24. More generally, the opening 27 is provided on the bottom surface 22 of the housing 2.

[49] The operation of actuator 1 will now be described. When the coil 5 is energized with an intensity greater than a threshold intensity, this makes it possible to move the piston 3 from the retracted position R to the deployed position D. When the piston 3 is in the deployed position D, the magnetic cover 8 exerts an attraction on the piston 3, which makes it possible to maintain it in the extended position D. The supply intensity of the coil 5 can then be reduced as long as it remains above said threshold intensity. When the coil 5 is de-energized or when it is supplied with an intensity lower than the threshold intensity, an elastic return means (not shown) returns the coupling device to the uncoupled position, which makes it possible to counter the force of attraction between the magnetic cover 8 and the piston 3 and returns the piston 3 from the extended position D to the retracted position R.

[50] The path of the fluid inside actuator 1 will now be described. The fluid enters the interior of the actuator 1 through the opening 25 and is guided by the outer surface 52 of the coil 5 (via the grooves 14a when they are present) towards the bottom surface of the housing 2 Then, the grooves 14b guide the fluid along the bottom surface of the casing 2. When the groove 24 exists, this groove 24 participates in the guiding of the fluid between the coil 5 and the casing 2. The fluid then passes through the passage located between the radial extension 7 and the radially inner skirt 21 of the housing 2. The fluid is then in the housing 11 in which the piston 3 is located. The fluid is then guided into this housing 11 by the grooves 12a which are located on the inner surface 51 of the coil. When the fluid is in the housing 11, it participates in the lubrication of the contact surfaces between the piston 3 and the radially internal skirt 21 of the housing 2. The fluid also participates in hydraulic damping when the piston 3 is at the end of its stroke, whether in the deployed position D or in the retracted position R. The fluid is then evacuated from the actuator 1 through the passage located between the magnetic cover 8 and the radially internal skirt 21 of the housing 2 or else through the opening 27.

[51] In general, the width of the grooves 12a, 12b, 14a, 14b, 24 is between 1mm and 5mm, preferably 2mm. The depth of the grooves 12a, 12b, 14a, 14b, 24 is between 1mm and 3mm.

[52] In general, the grooves 12a, 12b, 14a, 14b, 24 also have the function of participating in the filtration of the fluid as it travels inside the actuator 1.

[53] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[54] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

[Claim 1] Actuator (1) for a transmission system comprising a housing (2) defining an annular space of axis X, an annular piston (3) intended to transmit an actuation force to a coupling device, the piston (3) being disposed coaxially to the X axis and being mounted axially movable along the X axis between a retracted position (R) and an extended position (D), an annular coil (5) comprising a wire winding conductor, the coil (5) being encapsulated by a coating (6), characterized in that at least one means for guiding a fluid (12, 14a, 14b, 24) is provided between the housing (2) and the coating (6) of the coil (5).

[Claim 2] Actuator (1) according to Claim 1, characterized in that, seen in section, the casing (2) is U-shaped and is made of a single material, preferably a magnetic material.

[Claim 3] Actuator (1) according to claim 1 characterized in that, seen in section, the casing (2) is "U" shaped consisting of two assembled "L" shaped parts, the two parts being of preferably made of a magnetic material.

[Claim 4] Actuator (1) according to one of the preceding claims, characterized in that the housing (2) comprises a radially inner skirt (21), a bottom surface (22) and a radially outer skirt (23).

[Claim 5] Actuator (1) according to claim 4 characterized in that the means for guiding a fluid is at least one annular groove (24) located on the bottom surface (22) of the housing (2) in vis- opposite with a surface (53) of the coating (6) of the coil (5).

[Claim 6] Actuator (1) according to Claim 4 or 5, characterized in that the means for guiding a fluid is at least one groove (14b) located on a surface (53) of the coating (6) of the coil ( 5) facing the bottom surface (22) of the housing (2).

[Claim 7] Actuator (1) according to one of Claims 4 to 6, characterized in that the means for guiding a fluid is at least one groove (14a) located on the outer surface (52) of the coating (6) of the coil (5) facing the radially outer skirt (23) of the casing (2).

[Claim 8] Actuator (1) according to one of Claims 4 to 7, characterized in that the means for guiding a fluid is at least one groove (12a) located on the internal surface (51) of the coating (6) of the coil (5) facing the radially inner skirt (21) of the casing (2).

[Claim 9] Actuator (1) according to one of claims 4 to 8 characterized in that the housing (2) comprises an opening (25) located in the radially outer skirt (23), this opening (25) allows the passage fluid from the outside to the inside of the casing (2) as well as the passage of an electrical connector (10) of the coil (5).

[Claim 10] Actuator (1) according to one of the preceding claims, characterized in that the casing (2) is made of a material whose carbon content is less than 0.2%.]