Device for locking a powertrain transmission in a motor vehicle

Abstract

A device for locking a powertrain transmission in a motor vehicle, the device comprising: at least one toothed wheel (8); a rod (3) having a rod axis and comprising a first portion (31) provided with a right-handed external thread and a second portion (32) provided with a left-handed external thread; a driving member (4) for rotating the rod; two locking members (1, 2) each comprising a sleeve (10, 20) comprising an internal thread which interacts with the external thread of the rod by a complementary shape and a projection (5, 6) comprising a free end forming a stop for stopping the teeth of the toothed wheel in both directions; and a guide element (7) for preventing rotation of the locking member about the rod axis but allowing translation of the locking member along the rod axis.

Description

[0001] This invention relates to a device for locking the transmission system of a motor vehicle.

[0002] This type of locking device is commonly referred to as a parking brake and is routinely used, especially in vehicles with automatic transmissions. It is also used in electric or hybrid vehicles. The device for locking the transmission is activated when the driver typically places the gear selector in the "P" position while the vehicle is stationary.

[0003] The locking device discussed herein is separate from and complements another braking system also present in motor vehicles, known as the handbrake (which acts directly on the vehicle's wheels). The handbrake also serves as an emergency brake for slowing and stopping the vehicle. In contrast, the parking brake of this invention is configured and designed to engage only at zero or near-zero speed.

[0004] A known parking brake solution involves a toothed pivoting element (pawl) that selectively interferes with a toothed wheel that forms part of the transmission. However, this known solution occupies a significant amount of space and is not without clearance. An example of such a solution is known from US2016223082.

[0005] The inventors have sought to improve this situation and have proposed a novel configuration for performing parking brake functions.

[0006] For this purpose, a device is provided for locking a transmission by mechanically engaging at least one locking member in a toothed wheel of a powertrain transmission in a motor vehicle, the device comprising at least:

[0007] - A toothed wheel, which is rotatably mounted relative to the wheel axis.

[0008] - A rod, rotatably mounted in a housing about a rod axis, the rod comprising a first portion having a right-hand external thread and a second portion having a left-hand external thread.

[0009] - A drive member configured to selectively rotate the lever in one direction or another.

[0010] - A first locking member comprising a first sleeve centered on a rod axis and a first protrusion extending radially outward from the sleeve, the sleeve including an internal thread capable of interacting with an external thread of the rod through a complementary shape, the first protrusion including a free end forming a stop for stopping the teeth of a toothed wheel in a first rotational direction.

[0011] - A second locking member comprising a second sleeve centered on the rod axis and a second protrusion extending radially outward from the sleeve, the sleeve including an internal thread capable of interacting with another external thread of the rod through a complementary shape, and the second protrusion including a free end forming a stop for stopping the teeth of a toothed wheel in a second rotational direction.

[0012] - A guide element that prevents the first and second locking members from rotating about the rod axis but allows them to translate along the rod axis.

[0013] Because the rod has oppositely helical thread portions and the locking members engage around the rod through their respective corresponding internal threads, when the rod rotates in the first direction, these locking members move toward each other, and when the rod rotates in the other direction, these locking members move away from each other.

[0014] With these arrangements, when the locking members move toward each other, they engage one or more teeth of the toothed wheel, thus locking the toothed wheel. Conversely, when the locking members move away from each other, the toothed wheel rotates freely.

[0015] The proposed configuration is compact and easy to manufacture and assemble. The proposed configuration requires fewer parts than solutions known in the prior art, and, advantageously, is lighter than configurations known in the art.

[0016] Other advantages will be disclosed below.

[0017] The term “powertrain” here generally means any system that includes: an internal combustion engine or an electric motor; a transmission that includes a reducer having several selectable reduction ratios (if applicable); a differential; and two wheel axles that are connected to the left and right wheels of the vehicle axles, respectively.

[0018] According to one aspect, C2, each of the first and second protrusions is in the form of a finger-like portion extending along an inclined direction (X1, X2) relative to the rod axis. Therefore, the tip of the finger-like portion can be positioned between two teeth of the toothed wheel. The inclination of the finger-like portion allows it to absorb the force generated by the torque applied by the wheel, the finger-like portion operates essentially under compression, and the cantilever effect is minimized.

[0019] It should be noted that the term "arm" can also be used instead of "finger-like part" to refer to the protrusion.

[0020] According to one aspect, these fingers point towards each other. Therefore, they can grip the teeth of the toothed wheel like pliers. As a result, the clearance can be reduced to a very low value, or even zero.

[0021] C+ According to one aspect, the extension directions (X1, X2) are inclined at an angle θ relative to the rod axis, where θ is between 35° and 60°, and preferably between 40° and 50°. Therefore, a supporting effect is obtained in the direction in which rotation is prevented, wherein the fingers operate in a compressed state. The selected angle (or angle range) is the result of a trade-off between the clamping effect and a thinness that allows the fingers to be positioned between two teeth of the toothed wheel.

[0022] C4, according to one aspect, involves the ends of the first and second protrusions translating along the tangent of the main circle of the toothed wheel. It should be noted that this direction of movement is a unique feature compared to known prior art, in which the movable element moves radially toward the toothed wheel. This also reduces the radial space occupied relative to the axis of the toothed wheel.

[0023] According to one aspect, the rod axis (A) is perpendicular to the wheel axis (W). Therefore, it is not necessary to set a rotation axis parallel to the toothed wheel's axis near the toothed wheel. Apart from the toothed wheel's axis (W), the rod axis (A) is the only axis required in the proposed functional configuration.

[0024] According to one aspect, the first and second protrusions of the C6 generally extend in a radial plane (PR) perpendicular to the wheel axis (W). This results in a reduced footprint and a flat configuration that facilitates easy and compact integration into the transmission.

[0025] According to one aspect, in C7, the first and second protrusions act on the same tooth of the toothed wheel. Therefore, the locking system can be positioned in a reduced area relative to the toothed wheel. Consequently, the dimensional chain is as short as possible.

[0026] C8, based on one aspect, states that the number of teeth on the toothed wheel is between ten and twenty. Therefore, it maximizes the probability that the two finger-like parts of the locking member will directly lock the teeth when they move towards each other.

[0027] According to one aspect of C9, the rod is mounted and positioned between a bearing of the drive component and a bearing connected to the transmission housing. Therefore, the rod rotates within these two bearings, and the assembly is mechanically robust and capable of withstanding forces in both the axial and radial directions.

[0028] According to one aspect, the internal and external threads of C+ are fine threads, and the pitch PF is less than 12% of the diameter D3 of the rod. The outer diameter D3 of the rod can be, for example, between 8 cm and 16 cm, preferably between 10 cm and 12 cm.

[0029] This contributes to the irreversibility of the load path. In particular, when a vehicle is parked on an inclined surface (uphill or downhill), gravity (i.e., the weight of the vehicle) generates torque (static or even dynamic) on the toothed wheels, which is transmitted to the locking member and then to the thread and rod. However, even with a small pitch, the torque applied to the rod is insufficient to turn the motor or geared motor (actuator).

[0030] The present invention also relates to a motor vehicle transmission that includes a locking device as described above.

[0031] Further details of the invention are provided in the description of non-limiting embodiments and in the accompanying drawings illustrating variations thereof, in which:

[0032] -[ Figure 1 An elevation view schematically illustrates an example of a parking brake according to the present invention;

[0033] -[ Figure 2 A partial view of a threaded rod with opposite helical directions is shown.

[0034] -[ Figure 3 A cross-sectional view of the rod and the locking member with translational guidance is shown.

[0035] -[ Figure 4 This schematically illustrates an embodiment of the invention, wherein the parking brake function is disengaged;

[0036] -[ Figure 5 This schematically illustrates an embodiment of the invention, in which the parking brake function is engaged;

[0037] -[ Figure 6 Similar to Figure 5 It also schematically illustrates the specific situation before the lock was placed;

[0038] -[ Figure 7 This shows the tilting orientation of the finger-shaped part of the locking member.

[0039] In different accompanying drawings, the same reference numerals denote the same or similar elements. For clarity of description, some elements are not necessarily shown to scale.

[0040] In different accompanying drawings, the same reference numerals denote the same or similar elements. For clarity of description, some elements are not necessarily shown to scale.

[0041] Figure 1 An exemplary embodiment of the proposed locking device is shown. The locking device is arranged in the transmission housing (denoted as 9). The transmission can be an automatic transmission, but manual transmissions are not excluded. The transmission can also be a transmission for electric vehicles or hybrid vehicles.

[0042] Generally, a powertrain includes: an internal combustion engine or an electric motor; a transmission including a reducer with several selectable reduction ratios (if applicable); a differential; and two wheel axles, each connected to a corresponding wheel of the axle.

[0043] It should be noted that in the proposed configuration, a single locking device is sufficient to lock both wheels of the axle.

[0044] In the example shown, housing 9 contains various gears and pinions. Specifically, Figure 1 A transmission gear (denoted as 81) is shown, which is always engaged with a toothed wheel 8 via its outer peripheral teeth 81a. In some applications, the toothed wheel 8 is locked by a device described below.

[0045] The toothed wheel 8 is typically rigidly connected to the axle wheel, or at least rigidly connected to the wheel axle, via a transmission gear 81, to rotate with it. Therefore, locking the toothed wheel 8 allows the axle wheel of the vehicle to be fixed in place. A differential (not shown) may be located between the gear 81 and the wheel axle.

[0046] The toothed wheel 8 is rotatably mounted about a wheel axis (denoted as W). The toothed wheel 8 is mounted on a rotating or fixed shaft connected to the housing 9.

[0047] The toothed wheel 8 may have ten teeth, as shown in the figure. Generally, the number of teeth on the toothed wheel 8 is between ten and twenty. For example, the toothed wheel may have twelve teeth, or it may have sixteen teeth.

[0048] These teeth have a trapezoidal profile with steep sides. According to one embodiment, the sides 87 may be parallel to each other.

[0049] The outer diameter D8 of the toothed wheel 8 can be, for example, between 10 cm and 25 cm, preferably between 16 cm and 20 cm. The toothed wheel 8 is made of metal and is similar to a conventional pinion or gear.

[0050] The locking device includes a lever 3. The lever 3 is rotatably mounted in the housing about a lever axis (denoted as A).

[0051] For example, rod 3 is made of steel. Rod 3 includes a first journal near its first end close to the drive member and a second journal at its second end. The first journal is received in a bearing 34 of the drive member 4. The second journal is received in an opposing bearing 39. Bearing 39 can be connected to the housing via a bracket 38, or the bearing can be directly coupled into a cast hole in the housing 9.

[0052] The pivoting movement within the bearing lubricates the transmission housing by splashing oil from the moving parts. Additionally, lever 3 is fixed along axis A via the bearing. Therefore, the only degree of freedom granted to lever 3 is rotation about axis A.

[0053] The rod 3 includes two threaded portions with opposite directions of rotation. More specifically, the rod 3 includes a first portion 31 with a right-hand external thread 31a and a second portion 32 with a left-hand external thread 32a.

[0054] Internal and external threads are preferably fine threads. For example... Figure 2 As shown, the pitch (denoted as PF) corresponds to the distance between two successive threads. In the example shown, the pitch PF is less than 12% of the rod diameter D3. For example, for a rod diameter of 8 mm, the pitch PF is less than 1 mm.

[0055] The unthreaded portion 30 may be located between the two threaded portions. It should be noted that this invention covers any type of thread, including standard threads.

[0056] The outer diameter D3 of rod 3 can be, for example, between 8 mm and 16 mm, preferably between 10 mm and 12 mm.

[0057] A locking member movable along rod axis A is mounted on each of the two threaded sections.

[0058] The locking device includes a first locking component 1 and a second locking component 2.

[0059] The first locking member 1 includes a first sleeve 10 centered on the rod axis A. The first locking member 1 includes a protrusion extending radially outward from the first sleeve 10, referred to herein as the first protrusion 5.

[0060] The first protrusion is in the form of a finger or arm. This finger or arm extends from the sleeve along axis X1, which is inclined relative to rod axis A. The angle of inclination θ between axis X1 and rod axis A is between 35° and 60°. Preferably, θ is between 40° and 50°.

[0061] The first sleeve 10 includes an internal thread that can interact with the external thread 31a of the rod through a complementary shape.

[0062] The first protrusion includes a free end 51, which forms a stop for stopping the teeth of the toothed wheel in the first rotational direction S1 (see [reference]). Figure 4 The first protrusion includes the portion furthest from the rod axis, referred to as the back portion of the finger (denoted as 52), the purpose of which will be described below.

[0063] The second locking member 2 includes a second sleeve 20 centered on the rod axis A. The second locking member 2 includes a protrusion extending radially outward from the second sleeve 20, referred to herein as the second protrusion 6.

[0064] The second sleeve 20 includes a left-hand internal thread that can interact with the external thread 32a of the rod through a complementary shape.

[0065] The second protrusion 6 includes a free end 61, which forms a stop for stopping the teeth (same or different teeth) of the toothed wheel in the second rotation direction S2.

[0066] It should be noted that the finger-like parts point towards each other, like pliers or tweezers.

[0067] like Figure 7 As shown, the rod axis A is separated from the wheel axis W by a certain distance (denoted as D6). When the locking component is in the locked position, axes X1 and X2 intersect at point P12, which is separated from the rod axis A by a certain distance D7.

[0068] Depending on the wheel diameter, D7 can be between 25% and 50% of D6.

[0069] Additionally, the device includes a guide element 7. For example... Figure 3 As shown, the finger-like portion 5 extends between a first surface 71 that prevents it from rotating to the left and a second surface 72 that prevents it from rotating to the right. Other types of guides, such as lugs arranged diametrically opposite to the finger-like portion, are not excluded.

[0070] Generally, the guide element 7 prevents the locking members 1 and 2 from rotating about the rod axis A, but allows the locking members 1 and 2 to translate along the rod axis A.

[0071] The first protrusion 5 and the second protrusion 6 generally extend in a radial plane (denoted as PR) perpendicular to the wheel axis W. The plane PR passes through the axis A.

[0072] like Figure 3 As shown, the configuration of each component assembly is substantially flat in the Y direction. This is because the toothed wheel 8 and the fingers 5 and 6 extend on both sides of the radial midplane PR. Furthermore, the space occupied by each component (rod 3 and locking members 1 and 2) does not extend beyond the outer diameter D1 of the sleeve. Therefore, this assembly is easy to install in the narrow spaces of the transmission.

[0073] The locking members have internal threads corresponding to the threads of the rod. The first locking member has a right-hand internal thread, while the second locking member has a left-hand internal thread.

[0074] Although the first thread is a right-hand thread and the second thread is a left-hand thread, the opposite is certainly possible, where the corresponding threads on the rod portion are reversed.

[0075] It should be noted that the diameter of the rod outside the threaded portion can be reduced (< D3) so that the sleeve of the locking member can be inserted from the end of the rod into their position in the threaded portions 31, 32.

[0076] By means of the oppositely threaded portions 31a and 32a of the rod, when the rod 3 rotates in the first direction T1, the locking members 1 and 2 move toward each other. When the rod 3 rotates in the other direction T2, the locking members 1 and 2 move away from each other.

[0077] The drive component 4 can be, for example, an electric motor. The drive component may include a reducer, in this case, a geared motor. An output shaft (e.g., the rotor of a motor or the output shaft of a reducer) engages with the rod 3, for example, via a splined interface. A concave sleeve is rigidly connected to the rotor of the motor 4. The end of the rod on this side is a splined convex end. Other solutions (such as keying or using a through pin) are also possible.

[0078] It should be noted that the drive component 4 can be arranged outside the housing 9, and the rod 3 can have different lengths depending on the mounting configuration. This flexibility in the positioning of the drive component makes it easier to integrate the proposed solution into a given transmission configuration.

[0079] The drive mechanism is controlled by a control unit (not shown in the figure). The control unit receives vehicle-related speed information and can control the engagement of the parking brake when the vehicle speed is zero, or alternatively when the vehicle speed is below a very low threshold (e.g., below 3 km / h).

[0080] Figure 4 The diagram shows the starting configuration, where the toothed wheel can rotate freely around axis W. When conditions are met, the control unit can engage the parking brake.

[0081] For this purpose, the control unit rotates the lever along direction T1 by means of the electric motor 4, causing the locking members to move toward each other. Figure 5 The final configuration is shown, in which tooth 8a engages with the finger 5 of the first locking member 1 from above and with the finger 6 of the second locking member 2 from below.

[0082] The finger-like part grips the tooth 8a like pliers.

[0083] It should be noted that if tooth 8a is not precisely in the correct position during clamping, one of the fingers can move tooth 8a and thus the entire wheel 8 into the correct position as tooth 8a moves. The fine thread of the threaded portion allows for the application of significant force along axis A.

[0084] It should be noted that the finger-like portion translates along the tangent TG of the main circle of the toothed wheel. This configuration is ideal, allowing the finger-like portion to push the teeth of the wheel 8 in the circumferential direction via its side 87 and cause the wheel 8 to rotate.

[0085] Therefore, a recentering function is provided in case of incorrect tooth positioning.

[0086] according to Figure 6 In another scenario, where the fingers 5 and 6 are not gripping teeth when they move toward each other, the teeth of the wheel 8 can push one of the fingers to one side when the wheel 8 rotates slightly, causing the tooth to be received in the gap between the free ends of the fingers. Thus, the first tooth that enters the gap is captured.

[0087] For this purpose, the finger-like part can be deflected by pressing the back 52 of the finger-like part. For example... Figure 6 As shown, when the tooth contacts the second finger 6 of the second locking member 2, the second finger deflects upward, and the wheel 8 rotates in a clockwise direction.

[0088] Depending on the stiffness of the fingers and the rod, the rod can also bend slightly as the teeth pass over the back of the fingers. This flexibility can be sought so that tooth capture can be achieved even if the fingers have not yet gripped the teeth when they move toward each other.

[0089] The rod and locking mechanism are made of metal (such as steel).

[0090] It should be noted that the spiral joint between rod 3 and sleeves 10 and 20 is lubricated by splashing oil from the transmission.

Claims

1. A means for locking the transmission by mechanically engaging at least one locking member in a toothed wheel of a powertrain transmission in a motor vehicle, the means comprising at least: - A toothed wheel (8), which is rotatably mounted relative to the wheel axis (W). - Rod (3), which is rotatably mounted in the housing about a rod axis (A), the rod comprising a first part (31) provided with a right-hand external thread and a second part (32) provided with a left-hand external thread. - A drive member (4), which is configured to selectively rotate the rod in one direction or another direction (T1, T2). - A first locking member (1), comprising a first sleeve (10) centered on the axis of the rod and a first protrusion (5) extending radially outward from the sleeve, the sleeve comprising an internal thread capable of interacting with an external thread of the rod by means of a complementary shape, the first protrusion comprising a free end forming a stop for stopping the teeth of the toothed wheel in a first rotational direction (S1). - A second locking member (2), comprising a second sleeve (20) centered on the axis of the rod and a second protrusion (6) extending radially outward from the sleeve, the sleeve having an internal thread capable of interacting with another external thread of the rod through a complementary shape, the second protrusion having a free end forming a stop for stopping the teeth of the toothed wheel in a second rotational direction (S2). - Guide element (7), the guide element is used to prevent the first locking member and the second locking member from rotating about the rod axis but to allow the locking member to translate along the rod axis.

2. The locking device as claimed in claim 1, wherein, Each of the first protrusion and the second protrusion is in the form of a finger-like portion that extends along an extension direction (X1, X2) inclined relative to the axis of the rod.

3. The locking device as claimed in claim 2, wherein, The corresponding finger-like portions of the first protrusion and the second protrusion point towards each other.

4. The locking device as described in any one of claims 1 to 3, wherein, The ends of the first protrusion and the second protrusion translate along the tangent of the main circle of the toothed wheel.

5. The locking device as described in any one of claims 1 to 4, wherein, The rod axis (A) is perpendicular to the wheel axis (W).

6. The locking device as claimed in any one of claims 1 to 5, wherein, The first protrusion and the second protrusion generally extend in a radial plane (PR) perpendicular to the wheel axis (W).

7. The locking device as claimed in any one of claims 1 to 5, wherein, The first protrusion and the second protrusion act on the same tooth of the toothed wheel.

8. The locking device as claimed in any one of claims 1 to 6, wherein, The number of teeth on the toothed wheel (8) is between ten and twenty.

9. The locking device as claimed in any one of claims 1 to 7, wherein, The rod is mounted and located between the bearing (34) of the drive member and the bearing (39) connected to the transmission housing (9).

10. A transmission for a vehicle, the transmission comprising a locking device as claimed in any one of claims 1 to 9.

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