Actuator for a parking lock system of a vehicle gearbox

Abstract

The present invention relates to an actuator (1) for a parking lock system of a vehicle gearbox, the actuator (1) comprising a housing (10) having a first volume (V1) in which an electric motor (20) having a front face (20a) and a rear face (20b) is housed, and a second volume (V2) in which a reduction mechanism (70) kinematically connected to the electric motor (20) and a torque output element (80) are housed, the first volume (V1) being separated from the second volume (V2) by a wall (19) in which a circular opening (100) for the passage of an output shaft (23) of the electric motor (20) is formed, the opening (100) comprising at least one flat (100a, 100b, 100c) arranged at the periphery thereof, and the front face (20a) of the electric motor (20) being housed in the opening (100) so as to be in contact with the at least one flat (100a, 100b, 100c).

Description

Description Title of the invention: Actuator for a vehicle gearbox parking lock system [1] The invention relates to an actuator for a parking lock system for a vehicle gearbox, particularly a motor vehicle equipped with an automatic transmission, for example, a hybrid vehicle. The invention also applies to a parking lock system for a reduction gear associated with an electric vehicle motor. This locking system is better known by its English term "park-lock" or "parking lock". [2] Such an actuator allows the gearbox to be locked in parking position by means of a lever engaging with a gear of the gearbox. [3] An actuator of the same type is known from US document 2019136960 AA or a gear system of toothed wheel and worm gear is used to transmit the rotational motion of the electric motor to the torque output element of the actuator. [4] To minimize wear on a worm gear system, precise center distance between the worm and the gear is required. This precision is incompatible with the plastic molding process used to form part of the gear system. Accuracy on the order of a micron is required, and plastic only allows a deviation of + / -50 microns. [5] To achieve this, it is necessary to position the electric motor very precisely relative to the housing that receives the reduction mechanism, without forcing the electric motor into the housing. The risk is that excessive radial compression will reduce the lifespan of the internal bearing or bushing of the electric motor. [6] One of the aims of the invention is to provide a solution to this problem. To this end, the present invention provides an actuator for a parking lock system for a vehicle gearbox, said actuator comprising a housing having a first volume in which is housed an electric motor having a front face and a rear face and a second volume in which are housed a reduction mechanism in kinematic connection with the electric motor and a torque output element, the first volume is separated from the second volume by a wall in which is a circular opening allowing an output shaft of the electric motor to pass through, the opening includes at least one flat face disposed at its periphery and the front face of the electric motor is housed in the opening so as to be in contact with the at least one flat face. [7] This arrangement is advantageous because it minimizes the contact(s) of the front face of the electric motor within the housing, while ensuring reliable and functional mounting of the motor within the housing and minimizing wear on the worm gear system. This arrangement also has the advantage of perfectly immobilizing the front face of the electric motor within the housing, preventing play in the internal bearing or bushing of the front face, which can lead to motor malfunctions due to vibrations caused by inadequate immobilization. [8] According to the invention, the front face of the motor is cylindrical. The front face of the motor is the part of the motor that receives the bearing or bushing used to guide the rotation of the motor shaft. [9] According to the invention, three flats are arranged around the periphery of the circular opening, and two of these flats are positioned on a side opposite the reduction mechanism to the output shaft of the electric motor. This three-flat arrangement ensures an even more reliable and functional mounting of the electric motor in the housing.

[0010] According to one feature of the invention, two flat surfaces are arranged on a side opposite the reduction mechanism to the output shaft of the electric motor. This arrangement allows them to oppose the forces generated by the reduction mechanism.

[0011] Advantageously, a recess is located in the wall opposite a flat surface to allow for deflection of the wall material between the flat surface and the recess. Preferably, the material distance between the flat surface and The recess in the wall is between 1 and 3 mm. This arrangement allows for variations in tolerance, while guaranteeing zero play when the front face of the electric motor is engaged in the circular opening.

[0012] According to the invention, each flat surface is angularly spaced at approximately 120°, allowing for optimal arrangement around the periphery of the circular opening. A tolerance of plus or minus 10% can be applied.

[0013] According to an additional feature of the invention, the wall includes at least one passage for at least one power supply pin of the electric motor. Preferably, there are three passages for the three power supply pins of the electric motor. This arrangement allows the electric motor to be connected to an external power supply that is not located in the first volume.

[0014] According to the invention, the first volume extends partially into the second volume. Preferably, the housing is a single piece made of plastic. These characteristics result in a compact, lightweight, and easy-to-manufacture actuator.

[0015] According to the invention, the first volume is closed by means of a first hood which ensures centering of the rear face of the electric motor and allows the front face of the electric motor to be held in position in the circular opening.

[0016] Other features and advantages of the invention will become apparent from the following detailed example of an embodiment, with reference to the attached figures:

[0017] [Figure 1] represents a perspective view of the actuator according to the invention;

[0018] [Figure 2] represents a cross-sectional view of the actuator according to the invention;

[0019] [Figure 3] represents a cross-sectional view AA of [Figure 3],

[0020] It should be noted that the figures disclose the invention in sufficient detail for its implementation, and these figures help to further define the invention if necessary. However, the invention should not be limited to the embodiment disclosed in the description.

[0021] Figure 1 shows an actuator 1 for a parking lock system of a gearbox according to the invention. The term gearbox also refers to a reduction gear associated with an electric motor in the case of an electric vehicle. More specifically, this actuator 1 comprises a one-piece housing 10 consisting of a first volume V1 and a second volume V2.

[0022] The first tubular volume V1 contains a brushless DC electric motor 20, which includes an output shaft 23. Any other type of electric motor falls within the scope of this invention, such as a brushed DC motor. The second parallelepiped-shaped volume V2 primarily contains a reduction mechanism 70 kinematically linked to the electric motor 20 and two electronic boards. The first volume V1 is closed by means of a first cover 12, and the second volume V2 is closed by means of a second cover. The first cover 12 is attached to the housing 10 by means of metal clips 13. The second cover is attached to the housing 10 by any conventional fastening method, for example, screws.

[0023] The reduction mechanism 70 comprises a worm gear 22 positioned on the output shaft 23 of the electric motor 20 and meshes with a toothed wheel 30 on which the torque output element 80 is located. This torque output element 80 is in the form of a shaft concentric with the toothed wheel 30, the end of which has a star-shaped female socket into which an actuating rod (not shown) of a locking system is inserted to lock or unlock a gear of the gearbox (not shown) via an actuating lever or latch (not shown). Alternatively, the torque output element 80 can be in the form of a male socket. This torque output element 80 is guided in rotation by a shaft of the housing 10. A sealing means is positioned in this shaft to ensure that external contaminants do not enter the actuator 1.Similarly, a sealing means is provided between the hood 14 and the housing 10 and between the hood 12 and the housing 10.

[0024] Figure 1 also shows that the first volume V1 is separated from the second volume V2 by a wall 19 in which there is a circular opening 100 allowing the output shaft 23 of the electric motor 20 to pass through. In the In the embodiment shown in Figure 1, this opening comprises three flat surfaces 100a, 100b, 100c arranged around its periphery, and the front face 20a of the electric motor 20 fits into the opening 100 so as to be in contact with the flat surfaces 100a, 100b, 100c. This circular opening 100 will be detailed with reference to Figure 3. The wall 19 also includes three passages 120, 130, 140 for the three power supply pins of the electric motor 20.

[0025] The housing 10 is a single piece made of plastic. The first volume V1 extends partially into the second volume V2. The housing 10 also includes an electrical connector 15 for electrically connecting the internal components to the actuator 1.

[0026] Fastening means 11 in the form of metal inserts are arranged at several points on the housing 10 in order to allow it to be fixed to the vehicle's gearbox. In this case, three inserts 11 are provided.

[0027] Figure 2 illustrates an X, Y, Z coordinate system. The X direction or axis corresponds to a longitudinal direction. The Y direction or axis, which is transverse, is defined as being perpendicular to the longitudinal X direction. The Z direction or axis corresponds to a vertical direction.

[0028] Figure 2 shows more precisely the integration of the electric motor 20 into the housing 10. The brushless DC electric motor 20 has stator windings, a rotor, and an output shaft 23 connected to the rotor and extending along an X-axis. The stator windings forming the stator of the electric motor consist of three coils. The electric motor has a front face 20a and a rear face 20b; the front face 20a of the electric motor 20 fits into the opening 100.

[0029] A multi-pole magnet 21 is fixed to the output shaft 23 of the electric motor 20. The magnet 21 is annular in shape and coaxial with the output shaft 23. The magnet 21 has four poles. Of course, the magnet 21 can have a different number of poles.

[0030] The reduction mechanism 70 includes a fine screw 22 positioned on the output shaft 23 of the electric motor 20 and meshes with a toothed wheel 30 on which is located the torque output element 80. The torque output element 80 extends along a Z axis.

[0031] The output shaft 23 of the electric motor 20 is guided in rotation by three bearings and / or bushings. In the embodiment shown in Figure 2, a first bushing 18 and a bearing 17 are housed at the two ends of the electric motor housing, and a bushing 16 is housed in the housing 10 to guide the end of the output shaft 23 opposite the rotor. More specifically, the bearing 17 is housed in the front face 20a and the bushing 18 is housed in the rear face 20b of the electric motor 20.

[0032] The first volume V1 is closed by means of the first cover 12, which centers the rear face 20b of the electric motor 20 and holds the front face 20a of the electric motor 20 in position within the circular opening 100. To achieve this, the first cover 12 has an annular shape that allows it to cooperate with the rear face 20b of the electric motor. A spring system is positioned between the first cover and the electric motor 20 to axially press the electric motor 20 against the housing 10 and / or the wall 19.

[0033] The 100 opening allows the first volume and the second volume to be separated and will be discussed in more detail in figure 3.

[0034] The housing 10 also houses two electronic boards: a main electronic board and a secondary electronic board. Only the secondary electronic board 40 is visible in Figure 2. The main electronic board of the actuator enables the electronic control of the actuator and integrates electronic components necessary for the operation of the electric motor, such as, but not limited to, at least one capacitor, at least one resistor, at least one central processing unit (CPU), and an angular position sensor for the torque output element 80. The main electronic board has a shape substantially complementary to the shape of the periphery of the second volume V2 of the housing 10. The angular position sensor is a Hall effect sensor.The secondary electronic board 40 includes at least one device for determining the position of the electric motor rotor located with respect to the multi-pole magnet 21 in order to provide a signal necessary for the electronic switching of the power supply to the stator coils of the electric motor 20.

[0035] Figure 3 shows more precisely the circular opening 100 and the three flats 100a, 100b, 100c arranged around its periphery. Two of these flats 100a, 100b are positioned on the opposite side of the reduction mechanism 70 from the output shaft 23 of the electric motor 20; this feature is visible in Figure 1.

[0036] A recess 110 is located in wall 19 opposite the third flat 100c to allow for deflection of the wall material 19 between the third flat 100c and the recess 110. The material distance d between the flat 100a and the recess 110 of wall 19 is between 1 and 3 mm to allow optimal deflection without weakening the wall. Each flat 100a, 100b, 100c is angularly spaced at 120°. Wall 19 includes three passages 120, 130, 140 for the three power supply pins of the electric motor 20.

[0037] Although the invention has been described in connection with a particular embodiment, it is clearly not limited to it and includes all technical equivalents of the means described.

[0038] In claims, reference symbols in parentheses should not be interpreted as a limitation of the claim.

Claims

Demands

1. Actuator (1) for a parking lock system for a vehicle gearbox, said actuator (1) comprising a housing (10) having a first volume (V1) in which is housed an electric motor (20) having a front face (20a) and a rear face (20b) and a second volume (V2) in which are housed a reduction mechanism (70) kinematically connected to the electric motor (20) and a torque output element (80), the first volume (V1) is separated from the second volume (V2) by a wall (19) in which is a circular opening (100) for passing an output shaft (23) of the electric motor (20), characterized in that the opening (100) comprises at least one flat (100a, 100b, 100c) disposed at its periphery and the front face (20a) of the electric motor (20) fits into the opening (100) in order to be in contact with at least one flat (100a, 100b, 100c).

2. Actuator (1) according to claim 1, characterized in that three flats (100a, 100b, 100c) are arranged at the periphery of the circular opening (100).

3. Actuator (1) according to claim 1 or 2, characterized in that two flats (100a, 100b) are arranged on a side opposite to the reducing mechanism (70) with respect to the output shaft (23) of the electric motor (20).

4. Actuator (1) according to any one of the preceding claims, characterized in that a recess (110) is located in the wall (19) with respect to a flat (100c) in order to allow flexing of the material of the wall (19) between the flat (100c) and the recess (110).

5. Actuator (1) according to claim 4, characterized in that the distance (d) of the material between the flat (100c) and the recess (110) of the wall (19) is between 1 and 3mm.

6. Actuator (1) according to any one of claims 2 to 5, characterized in that each flat (100a, 100b, 100c) is angularly spaced at approximately 120°.

7. Actuator (1) according to any one of the preceding claims characterized in that the wall (19) includes at least one passage (120, 130, 140) for at least one power supply pin of the electric motor (20).

8. Actuator (1) according to any one of the preceding claims characterized in that the first volume (V1) extends partially into the second volume (V2).

9. Actuator (1) according to any one of the preceding claims characterized in that the housing (10) is one piece and made of plastic.

10. Actuator (1) according to any one of the preceding claims characterized in that the first volume (V1) is closed by means of a first cover (12) which ensures centering of the rear face (20b) of the electric motor (20) and allows the front face (20a) of the electric motor (20) to be held in position within the opening (100).]

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