WO2022037741A1

WO2022037741A1 - Parking lock

Info

Publication number: WO2022037741A1
Application number: PCT/DE2021/100539
Authority: WO
Inventors: Terence KOFFMANE; Stanislav Massini; Andreas Schulte; Dominik Meidenbauer
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2020-08-17
Filing date: 2021-06-25
Publication date: 2022-02-24
Also published as: DE102020121495A1; DE102020121495B4

Abstract

The invention relates to a parking lock (1) for a vehicle, comprising a parking lock wheel (2), which has multiple teeth (22) and tooth gaps (23) as radial recesses (3) and is rotatable about an axis of rotation (12) when in the unlocked state, and a blocking element (4) which, when in the locked state, engages with one of the radial recesses (3), and an axially movable actuator (5), the actuator (5) axially enclosing the blocking element (4) on both sides.

Description

parking lock

The invention relates to a parking lock for a motor vehicle, in particular for an automatic transmission or a vehicle with an electric drive.

Background of the Invention

Parking locks are used in motor vehicle transmissions to secure the vehicle against unintentional rolling away. In particular, when non-mechanical components are installed in a drive train of a motor vehicle, such as in automatic transmissions with hydrodynamic torque converters, parking locks secure the vehicle position when the vehicle is stationary or the engine is switched off. To do this, the parking lock can be activated by the driver or indirectly via electrical aids. It then generally blocks the transmission output shaft in a form-fitting manner.

DE 1 043 829 A1 provides a parking lock in the form of a pawl which can be pivoted against a restoring force and which can positively engage by means of a ratchet tooth in a locking toothing arranged on the outer circumference of a parking lock wheel. Once the positive connection has been established, it prevents the parking lock gear, which is arranged non-rotatably on the transmission output shaft, from moving and thus preventing the vehicle from moving.

The pawl is actuated by a linearly displaceable actuating unit, which has a frame-like shape as a carriage, with a selector lever acting on longitudinally running side walls of the frame-like linkage. The actuation unit has two rollers mounted together, via which it acts on the pawl. The pawl must be able to hold the parking lock wheel securely and engage and disengage even at low vehicle speeds up to a limit speed of around 5 km/h and on uneven ground with a gradient of up to 30°. When engaging and disengaging the parking lock, depending on the vehicle weight, forces in the double-digit kN range occur. Accordingly, in the case of a meshing contact, the components must be dimensioned larger, which in turn is associated with a higher mass. In particular, the pawl (locking element that engages the parking lock wheel in the drive train via a mechanism) must be solid to absorb these high loads.

Static forces that act in the parked position are offset by dynamic forces that occur during so-called ratcheting, the deflection of the pawl from the limit speed, occur to distinguish. As a result of the high ratchet mass, very high accelerations occur, mainly during the ratcheting process, which result in high dynamic inertial forces that have to be absorbed.

Furthermore, when the parking lock is engaged, especially on slopes, holding the entire vehicle creates high supporting forces in the drive train in addition to the torsional moment. The reason for this is the one engagement contact, which produces a circumferential force component for holding the vehicle and a radial force component. The radial force component acts in one direction on the shaft bearing and in the other direction on the pawl support in the housing. This requires the use of larger shaft bearings and measures to absorb the high contact pressure between the pawl and the housing.

According to DE 10 2016 201 228 A1, the resulting load peaks can be reduced by using two pawls for locking. However, due to the manufacturing process, it is not guaranteed that both pawls will strike at exactly the same time, so that at least when the parking lock is engaged, the full load is applied to one pawl. This can only reduce the static permanent load. In order to reduce the mass of a parking lock, DE 10 2016 201 228 A1 proposes locking using a plurality of locking elements. The disadvantage is that the locking elements spring in independently of one another and consequently the maximum load when the parking lock is engaged is also supported by only one locking element.

object of the invention

The object of the invention is to avoid the shortcomings of the known solutions and to create a parking lock that is lightweight and compact.

Summary of the Invention

The object of the invention is achieved by a parking lock according to claim 1. Since the actuator encloses the locking element axially on both sides, it can be arranged coaxially with the parking lock wheel and takes up very little installation space. In particular, a swept angular range of a pawl is eliminated. Furthermore, it can thereby be arranged spatially close to the teeth of the parking lock wheel, as a result of which tolerances that occur can be minimized. It is particularly advantageous to form the actuator in the shape of a ring. An annular actuator can act on one or more locking elements at the same time and thus reliably support the forces that occur when the parking lock is engaged. An actuator that can move axially or in the circumferential direction is particularly advantageous when there is little radial installation space available, for example when the parking lock is integrated into an electrically driven axle. The ring-shaped actuator can be arranged offset axially to the parking lock wheel or surround it radially.

The use of several locking elements actuated at the same time results in the following advantages: On the one hand, the reaction forces on the transmission bearings can be reduced or even eliminated through a targeted arrangement of the locking elements. The blocking elements are preferably arranged rotationally symmetrically. As a result, the radial force components of the individual contacts partially or ideally completely cancel each other out. On the other hand, the required installation space can be reduced by better stressing of the components or reducing the load in the individual intervention. It is advantageous to act on the blocking elements via ramp contours. For this purpose, the actuator can have a ramp for each blocking element, which forms a radial restraint in the case of axial displacement.

The simultaneous and therefore simultaneous movement of the blocking elements ensures that the load is actually distributed over several blocking elements. The blocking elements can have a small amount of play in their direction of movement, so that when the blocking elements are loaded unevenly at first, there is a compensation between the blocking elements via the actuator.

With the multiple contacts, it must be ensured that all contacts block at the same time in order to then distribute the load as evenly as possible when the vehicle is stopped.

The simultaneous engagement or synchronization of all locking elements is a major advantage of a parking lock with multiple contacts, since all elements are only engaged when they are in their predetermined position relative to the mating component. The synchronized insertion is effected by the actuator.

It is not necessary for the invention that all blocking elements are moved synchronously at all times. Rather, it is sufficient to provide an initial movement of one of the blocking elements. Only after the blocking element has been pre-positioned is the initial movement or a subsequent movement synchronized to all blocking elements via the actuator. In a particularly simple embodiment, the blocking elements are all or partially guided through the actuator, so that the latter forms a guide element for the blocking elements. For this purpose, the blocking element carrier can be constructed like a cage and have a plurality of pockets, in each of which at least one blocking element is arranged. The blocking elements are preferably designed as balls.

When the drive train is blocked, the load is distributed evenly via the rigidity of the individual components or the entire system. The production tolerances that flow in must be absorbed by the softness of the system in order to counteract overloading in the individual contact and the failure or destruction of the parking lock. Damping elements such as elastomers are suitable for smoothing peak loads.

The parking lock can be returned from the locked state (locked position) to the unlocked state (unlocked position) by a mechanically, hydraulically or electrically actuated mechanism. In a simple case, the mechanism acts on an axially directed wall of the actuator.

The actuator is prestressed by a spring, which is preferably supported on the actuator and on the carrier body accommodating the blocking bodies. If this rests on the outer circumference of a carrier body designed as a collar, it requires very little additional installation space.

The parking lock according to the invention is suitable for vehicles, in particular motor vehicles. The locking elements can be brought into engagement with the radial recesses. To do this, they can engage in the radial recesses. As an alternative or in addition, they are secured after they have engaged in the radial recesses, so that further movement is precluded. The parking lock is compact, since the tooth height of the parking lock gear does not have to accommodate the complete locking element in the radial direction, but forms a pocket together with the component radially surrounding the parking lock gear, so that the parking lock is radially small. Only a slight axial displacement is required for the actuator, so that the parking lock is also constructed in a compact manner in this direction. In particular, no space is required, which is swept by a lever-like pawl.

Brief description of the drawings The invention is further described below using an exemplary embodiment. Show it:

Figure 1 shows a first parking lock according to the invention in a perspective view,

FIG. 2 shows the parking lock according to FIG. 1 in an enlarged, partially sectioned view,

FIG. 3 shows the parking lock according to FIG. 2 in a further enlarged, partially sectioned view in the disengaged state,

FIG. 4 shows the parking lock according to FIG. 2 in a further enlarged, partially sectioned view in the engaged state,

Figure 5 shows a second parking lock according to the invention in a perspective view and

FIG. 6 shows the parking lock according to FIG. 1 in an enlarged, partially sectioned view.

Detailed description of the drawings

1 to 4 show a first parking lock 1 according to the invention with a parking lock gear 2 fixed to the transmission shaft. The parking lock gear 2 has teeth with teeth 22 and tooth gaps 23 which form radial recesses 3 on its outer circumference. In the locked state of the parking lock 1, the radial recesses 3 accommodate locking elements 4 and their contour is adapted to that of the locking elements 4, although not necessarily designed to complement them. A support body 21 surrounds the parking lock wheel 2 radially and has pockets 7 . Exactly one blocking element 4 is arranged in each pocket 7 and guided axially through the carrier body 21 . The carrier body 21 also has a flange section 29 with through-holes 30, via which it can be screwed to a transmission housing.

In the present case, the blocking elements 4 are designed as balls.

The parking lock gear 2 is also surrounded radially by an actuator 5 . The actuator 5 can be rotated axially in the direction of the axis of rotation 12 of the parking lock wheel 2 and has ramp contours 24 along which the locking elements 4 can slide or roll. the ramp Contours 24 are part of locking element pockets 31 of the actuator 5, which border the locking elements 4 radially on the outside. The actuator 5 thus forms a blocking element carrier 6 .

When the parking lock 1 is in the open state, the blocking elements 4 are located radially on the outside on a ramp contour 24 of the actuator 5 . In the present case, the actuator 5 has a common ramp contour 24 for all blocking elements 4 . So that the locking elements 4 do not fall into the tooth gaps 23 in the open state of the parking lock 1, for example due to gravity, the actuator 5 has a locking element holder 25 which is arranged radially inside the carrier body 21 and prevents the locking elements 4 from falling into the tooth gaps 23 of the parking lock wheel 2 . The blocking element holder 25 can be designed as an independent component or can be permanently connected to the actuator 5 or the carrier body 21 . In the present case, the blocking element holder 25 is a ring element that has retaining lugs 32 . The retaining lugs 32 ensure that the blocking elements 4 are always pressed radially outwards against the ramp contour 24 of the actuator 5 in the open state. The blocking elements 4 are thus located radially on the outside of the ramp contour 24 of the actuator 5 when the parking lock 1 is in the open state. The blocking element holder 25, which is designed as a spring element, presses the blocking elements 4 against the ramp contour 24, so that the blocking elements 4 alone can fall into the gaps 23 of the Parking lock wheel 2 is not possible.

To close the parking lock 1 , an actuating unit 20 , shown only schematically, moves in the direction of insertion 10 , to the left in the drawing, and releases the axial movement of the actuator 5 along the axis of rotation 12 . In the present case, the actuation unit 20 can be part of a linear actuator with an axis that moves in and out (not shown) or a shift fork.

The carrier body 21 is designed as a sleeve with an axial section 26 and a flange section 29 . A compression spring 28 is arranged on the axial section 26 of the carrier body 21 and pretensions the parking lock 1 . If its movement is released, the actuator 5 moves away from the flange section 29 and forces the locking elements 4 to be inserted into the tooth gaps 23 via the ramp contours 24. The movement takes place against the spring force of the locking element holder 25.

The actuator 5 has an annular area 35 extending towards the flange section 29, into which the ramp contour 24 runs out. The annular area 35 is arranged coaxially to the axial section 26 of the carrier body 21 and, when the parking lock 1 is in the engaged state, covers the locking elements 4 radially. It thus prevents the parking lock 1 from being disengaged automatically. In the present case, the compression spring 28 is designed as a wave spring. When the locking elements 4 enter the parking lock wheel 2, above the limit engagement speed of the vehicle (or speed of the transmission shaft), the shape of the locking elements 4 designed as balls and the contour design of the teeth 22 of the parking lock wheel 2 will cause the locking elements to be deflected radially outwards. Correspondingly, the actuator 5 is moved back axially against the spring force of the compression spring 28 .

Below the limit speed, the locking elements 4 dip into the next tooth gap 23 of the parking lock wheel 23 . The actuator 5 is moved axially to the left by the compression spring 28 up to an end stop (not shown), which is preferably arranged on the actuation unit 20 . As soon as the cylindrical ring area 35 of the actuator 5 is above the locking elements 4, these can no longer be pressed radially outwards and the parking lock is closed. The torque for holding the vehicle is transmitted via the vehicle wheel to the transmission shaft (not shown) to the parking lock wheel 2 and from here via the balls 4 in contact to the carrier body 21 to the transmission housing (not shown).

Since all locking elements 4 are in a common locking element carrier 6, they are moved in the same direction of rotation. In the present case, the locking element carrier 6 forms the actuator 5 itself and synchronizes the movement of all locking elements 4 by synchronously taking them along via the corresponding counter-contour of the parking lock wheel 2 .

Before the parking lock 1 is disengaged, the locking elements 4 are in the tooth gaps 23 of the parking lock gear 2. When the parking lock 1 is opened, the actuation unit 20 moves to the right and presses the actuator 5 against the spring force of the compression spring 28. As a result, the actuator 5 moves along the Axis of rotation 12 axially. As soon as the radial movement of the blocking elements 4 is released by the actuator 5, they are pressed radially outwards by the torque applied to the parking lock wheel 2 via the blocking element and tooth flank contour.

The actuation unit 20 presses the actuator 5 up to a certain stroke distance or a firm stop on the carrier body 21. The actuation unit 20 remains in this position and is also locked if necessary, whereby the parking lock 1 remains in the open state and the parking lock wheel 2 rotates freely with the transmission shaft can. 5 and 6 show a second parking lock 20 according to the invention. In contrast to the first embodiment according to FIGS. The actuator 5 encapsulates the three compression springs 28 so that they are held captive.

Reference character list

parking lock

parking lock wheel

radial recess

blocking element

actuator

(locking element carrier)

bags

direction of insertion

direction of laying out

axis of rotation

actuation unit

carrier body

tooth

tooth gap

ramp contour

locking element holder

Axial section of the carrier body

radial protrusion

compression spring

flange section

through hole

locking element pocket

holding lug

groove

pen

ring area

Claims

Claims Parking lock (1) for a vehicle with a parking lock wheel (2), which has a plurality of teeth (22) and tooth gaps (23) as radial recesses (3) and can be rotated about an axis of rotation (12) in the unlocked state, with a locking element (4 ), which in the locked state is in engagement with one of the radial recesses (3), and with an axially movable actuator (5), characterized in that the actuator (5) encloses the blocking element (4) axially on both sides. Parking lock according to claim 1, characterized in that the actuator (5) is annular. Parking lock according to Claim 1 or 2, characterized in that the parking lock (1) has a plurality of locking elements (4) which, when the parking lock (1) is in the locked state, are arranged in different radial recesses (3) and together form the lock. Parking lock according to one of the preceding claims, characterized in that the actuator (5) has a ramp (24) for each blocking element (4) which forms a radial restraint for each blocking element (4) when the actuator (5) moves axially. Parking lock according to one of the preceding claims, characterized in that the parking lock (1) has a carrier body (21) through which all locking elements (4) are guided. Parking lock according to Claim 5, characterized in that an axial section (26) of the carrier body (21) is surrounded radially on the outside by the actuator (5). Parking lock according to Claim 5 or 6, characterized in that the parking lock (1) has a ball mount (25) which is arranged radially on the inside of the carrier body (21) and acts on the blocking element (4) with a radially outward force. Parking lock according to one of the preceding claims, characterized in that the parking lock (1) has a spring (28) for prestressing the parking lock (1), which is supported on the carrier body (21) and on a radial projection (27) of the actuator and is guided through the actuator (5). Parking lock according to one of the preceding claims, characterized in that the actuator (5) has a radial end wall (35) by means of which the parking lock (1) can be engaged and disengaged. Parking lock according to one of the preceding claims, characterized in that the tooth height of the teeth (22) of the parking lock wheel (2) is less than half the radial diameter of each locking element (4).