FR3069608B1 - SYSTEM FOR CONTROLLING A PARKING LOCK TO BLOCK A TRANSMISSION OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a control system of a parking lock for locking a transmission of a motor vehicle, comprising a motor (2) driving a screw rotation, and having a nut (44) engaged on the screw , rotatably locked and axially slidable by acting on a locking lever of the transmission, this control system being remarkable in that the nut (44) has a constant cross-section which is not circular, and in that the motor (2) comprises a cover (30) comprising a bore (56) fittingly receiving the cross section of the nut (44).

Description

The present invention relates to a control system for a parking lock of a motor vehicle transmission, as well as to a transmission comprising a control system for a parking lock of a motor vehicle transmission, and a transmission comprising such a control system of its parking lock, and a motor vehicle equipped with a transmission comprising this control system.

[0002] Certain motor vehicle transmissions, in particular automatic gearboxes for heat engines or speed reducers for electric vehicles, comprise a parking lock that makes it possible to stably block a rotating element of the transmission permanently connected to the vehicles. drive wheels of the vehicle.

A control maneuvered by the driver on the stationary vehicle, generally using the control lever of the transmission, has the parking lock in its blocking position to keep the vehicle stopped. The blocking position is maintained in particular after stopping the engine and cutting off the vehicle contact, which removes any source of energy for the transmission, to ensure safety.

A known parking lock system, presented in particular by DE-A1-102015100067, comprises a locking lever having an end fixed by a pivot to the transmission housing, and another end comprising a finger which goes down into a succession of depressions made on a parking wheel permanently linked to the driving wheels of the vehicle, to lock this wheel.

A longitudinally sliding shaft is connected to a cam which pushes on the locking lever behind its finger, in order to control this lever.

Alternatively a known type of control of the locking lever comprises a screw fixed to the end of the shaft of an electric motor, which moves axially a nut locked in rotation, connected to a carriage to drive it. The carriage has a support cam on the lever behind its finger.

The linear guide of the carriage is formed by a slide receiving the carriage, formed in a folded sheet, having on two opposite sides a longitudinal groove each receiving a boss of the nut to prevent it from rotating.

This type of control has problems assembling the nut in the linear guide slide. Engaging the bosses in the longitudinal grooves is not easy to achieve. In addition, the grooves machined on the sides of the slide for guiding the nut, weaken this slide.

The present invention is intended to avoid these disadvantages of the prior art.

It proposes for this purpose a control system of a parking lock for blocking a transmission of a motor vehicle, comprising a motor driving a rotation screw, and having a nut engaged on the screw, locked in rotation and sliding axially by acting on a locking lever of the transmission, this control system being remarkable in that the nut has a constant cross section which is not circular, and in that the motorization comprises a cover comprising a receiving bore in a manner adjusted the cross section of the nut.

An advantage of this control system is that the boring of the hood adjusted to the cross section of the nut having a non-circular section, is a compact, rigid and economical means of maintaining this nut in rotation while allowing free axial sliding.

In addition, the assembly is easily done by simply engaging the nut in the bonnet hole.

The lock system according to the invention may further comprise one or more of the following features, which may be combined with each other.

Advantageously, the hood has a cylindrical shape aligned with the axis of the engine, comprising a rear end which fits on a circular front boss of this engine.

In this case, advantageously the boss before the engine has lugs fitted into the cutouts of the rear end of the hood, and an open ring is engaged on an outer circular groove formed both on the hood and on the pins.

Advantageously, the nut has a cross section comprising along its length longitudinal tenons.

Advantageously, the control system comprises axial end stops of the nut, arranged inside the cover.

[0018] Advantageously, the axial stops comprise Belleville washers.

In particular, the control system may comprise a front Belleville washer arranged axially between a rear snap ring fixed on the nut, and a transverse front end face of the cover.

In particular, the control system may comprise rear Belleville washers arranged axially between the rear end of the nut, and the engine.

The invention also relates to a transmission for a motor vehicle equipped with a parking lock, remarkable in that the parking lock comprises a control system comprising any one of the preceding features.

The invention further relates to a motor vehicle having a transmission equipped with a parking lock, remarkable in that the parking lock comprises a control system comprising any one of the preceding features.

The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the explanatory description which follows, with reference to the accompanying drawings given solely by way of illustrative example. an embodiment of the invention, and in which: - Figure 1 is a view of a parking lock system according to the prior art; and FIGS. 2 and 3 are views respectively external and in axial section of a parking lock system according to the invention.

Figure 1 shows a lock system comprising an electric motor 2 disposed along a longitudinal axis, having the front side indicated by the arrow "AV >>, a circular portion 4 of centering in a housing of a transmission, and just back an axial bearing flange 6 having holes provided for fixing the engine on the housing.

A support 8 formed by a folded sheet, fixed to the transmission casing by screws 10, comprises a slide aligned longitudinally on the axis of the motor 2, having a cross section in the form of "U".

One side of the support 8 down below the slide, supports a transverse axis 12 receiving the front end of a locking lever 14. The rear end of the locking lever 14 comprises a finger 16 fitting into a series of recesses 18 distributed around a parking wheel 20 mounted on a shaft not shown, permanently connected to the driving wheels of the vehicle.

A nut engaged on a threaded rod 24 fixed to the end of the motor shaft 2, has on each side a boss 28 engaged in a longitudinal groove 26 cut on each side of the support 8, so as to prevent the rotation of this nut while allowing its sliding in the longitudinal direction.

The nut axially drives a carriage guided in the slide of the support 8, which comprises a cam acting on the back of the locking lever 14 to lower its finger 16 in a recess of the parking wheel 18.

An inverse movement of the cam of the carriage releases the locking lever 14, which rises under the effect of a spring 22 comprising turns wrapped around the transverse axis 12, maintaining a constant load on the lever for the raise. The finger 16 of the locking lever 14 then emerges from the recesses of the parking wheel 18, to unlock the transmission.

This type of parking lock actuator poses several problems. Mounting the carriage with its nut is difficult because it is necessary to align the two bosses 28 of the nut on the longitudinal grooves 26 of the support 8, which is tricky. The realization of these grooves 26 by machining the sidewalls of the plate of the support 8, weakens this support.

In addition the position of axial end stops of the carriage is given by the stack of many parts passing through the support 8 and the motor 2, which gives significant manufacturing dispersions on these positions.

Figures 2 and 3 show an electric motor 2 having at its front end a circular boss before 32 forming a nose centered on the main axis of the engine, receiving the rear end of a cap 30 of cylindrical shape. The circular circular boss 32 has two lugs 34 diametrically opposed, each engaging in a cut made on the rear of the cover 30 to prevent rotation.

The rear end of the hood 30 has a transverse circular groove formed around the hood, which is extended by similar grooves formed on the outside of each lug 34. An open circular ring 36 is engaged both in the groove of the hood 30 and in that of the lugs 34, tightening at the bottom of these grooves by elastic deformation to ensure a maintenance of the bonnet resistant to axial force. The behavior of the hood 30 at the torque along the axis is provided by the lugs 34.

Alternatively the cover 30 may be attached to the electric motor 2 by any other method, such as crimping, welding or gluing.

Behind the cover 30, the motor 2 comprises a cylindrical portion 40 receiving in an annular groove an O-ring made of elastomer 38, intended to be clamped in a bore of the transmission housing to ensure a seal.

The front end of the cap 30 is closed by a transverse end face comprising in the center a bore 56 fittingly receiving the cross section of a nut 44 aligned on the axis, which is not circular. In particular, the cross section of the nut 38 comprises two longitudinally elongate lugs 46 arranged in opposition, each having parallel flanks bearing on the corresponding shape of the boring of the cap 56, to support a torque while allowing the sliding of this nut. .

The axially elongated nut 44 is engaged over a long length, on a screw 42 attached to the end of the motor shaft 2. The rotation of the motor 2 causes a screwing or unscrewing of its screw 42 with respect to the nut 44 locked in rotation, which then slides in one direction or the other.

The rear end of the nut 44 has a circular outer groove receiving a snap ring 48. A front stop formed by a Belleville washer before 50, is adjusted around the nut 44 and in the cylindrical portion of the hood 30.

The nut 44 arriving at the end of the forward stroke, the snap ring 48 bears on the inner diameter of the Belleville washer before 50, its outer diameter bearing on the front transverse face of the cover 30.

Obtaining a limit stop before slightly elastic, formed with very few curly elements between the motor 2 and its cover 30 forming a subassembly, which limits the manufacturing dispersions of the axial positioning of this stop . The stiffness of this limit stop is easily adjustable by choosing the characteristics of the Belleville washer before 50.

Two rear Belleville washers 52 arranged in opposition, are fitted around the screw 42, behind the nut 44.

The nut 44 arriving at the end of the rear stroke, its rear end is supported on the inner diameter of a first Belleville rear washer 52, which transmits this support by its outer diameter on the second washer Belleville disposed in opposition. The second rear Belleville washer 52 is supported itself on a rear ring 54 axially locked on the engine 2.

In the same manner, a slightly elastic rear limit stop is obtained, having a precise axial positioning, the stiffness of which can be easily adjusted. In particular, after assembly of the subassembly, during operation of the electric motor 2, it is possible to learn the positions of the front and rear stops, by controlling this motor with a detection of the rising of the forces on the abutments making it possible to stop the control before blocking this motor, and to locate the axial positions accurately.

The nut 44 is connected to a carriage, not shown, sliding axially, which controls the engagement or release of a locking lever 14, to actuate the parking lock of a transmission.

Advantageously the electric motor 2 equipped with the screw 42, the nut 44 and the cover 30, forms a subset easily assembled and prepared at a supplier, who is ready to be placed on a transmission by the manufacturer of this transmission. This subassembly can be tested at the end of assembly, to guarantee all performances.

In this way the manufacturer of the transmission does not intervene in the assembly and internal adjustments of the axially sliding system, in particular in the positioning of the stops which are set in advance.

Claims (10)

1. Control system of a parking lock for blocking a transmission of a motor vehicle, comprising a motor (2) rotating a screw (42), and having a nut (44) engaged on the screw (42). , locked in rotation and axially slidable by acting on a locking lever (14) of the transmission, characterized in that the nut (44) has a constant cross-section which is not circular, and that the motorization ( 2) comprises a cover (30) comprising a bore (56) fittingly receiving the cross section of the nut (44). 2. Control system according to claim 1, characterized in that the cover (30) has a cylindrical shape aligned with the axis of the operator (2), comprising a rear end which fits on a circular front boss (32). ) of this motorization (2). 3. Control system according to claim 2, characterized in that the front boss (32) of the actuator (2) comprises lugs (34) fitted into cutouts of the rear end of the hood (30), and in that an open ring (36) is engaged on an outer circular groove formed on both the hood (30) and the lugs (34). 4. Control system according to any one of the preceding claims, characterized in that the nut (44) has a cross section comprising along its length longitudinal tenons (46). 5. Control system according to any one of the preceding claims, characterized in that it comprises axial end stops of the nut (44), arranged inside the cover (30). 6. Control system according to claim 5, characterized in that the axial stops comprise Belleville washers (50, 52). 7. Control system according to claim 6, characterized in that it comprises a front Belleville washer (50) disposed axially between a rear snap ring (48) fixed on the nut (44), and a transverse face of front end of the hood (30). 8. Control system according to claim 6 to 7, characterized in that it comprises rear Belleville washers (52) arranged axially between the rear end of the nut (44), and the motor (2). 9. Transmission for a motor vehicle equipped with a parking lock, characterized in that the parking lock comprises a control system according to any one of the preceding claims. 10. Motor vehicle comprising a transmission equipped with a parking lock, characterized in that the parking lock comprises a control system according to any one of claims 1 to 8.