FR3072141A1 - GEARBOX SYNCHRONIZER HAVING A REVERSE REVERSE BRAKE SYSTEM WITH A LEVER, AND A MOTOR VEHICLE EQUIPPED WITH SUCH A SYNCHRONIZER - Google Patents

Abstract

Gearbox synchronizer in particular of a motor vehicle, provided with a reverse brake system (3) with levers (4) interposed between a synchronizing hub and a stop plate and pivotally bearing on the stop plate and by their ends on at least two pushing fingers (24) resting on a friction ring of the synchronizer. This synchronizer comprises an antivibration device (5), which comprises a circular spring (33) arranged coaxially with the ring of the levers (4) bearing on the radially inner face thereof in order to constrain the levers (4) radially. against the push fingers (24). The invention is usable for motor vehicles.

Description

The invention relates to a gearbox synchronizer, provided with a reverse brake system with levers, comprising at least two reversing levers in the form of an arc of a circle, arranged so as to form a crown and interposed between a synchronization hub and a stop plate of the synchronizer, and which are in pivoting support on the stop plate and by their ends on at least two push fingers which pass through the hub to come to bear on a friction ring of the synchronizer. The invention also relates to a motor vehicle equipped with such a synchronizer.

A synchronizer of this type is described in French patent no. 2,959,543. The lever-operated reverse brake system mounted in the fifth gearbox synchronizer, while rotating at the speed of the synchronizer, undergoes all of its revs and accelerations. Although this system is only functional when engaging reverse gear, it is permanently driven on all gear ratios and for all engine speeds. The play necessary for its operation implies possibilities of vibrations and noise of the levers, which could annoy the driver. Furthermore, the tolerance intervals necessary for the manufacture of the components of this reverse brake, but also of the synchronizer, generate more or less significant play of all the components and in particular of the reverse brake levers.

The invention aims to overcome the problem of vibration and noise which has just been invoked.

To achieve this goal, the synchronizer is characterized in that it comprises an anti-vibration device which comprises a circular spring arranged coaxially with the crown of the levers by bearing on the radially internal face of these so as to force the levers radially against the push fingers.

According to an advantageous characteristic of the invention, the circular spring is a leaf spring.

According to another characteristic of the invention, the spring is punctually supported on each lever as close as possible to the pivot axis thereof.

According to yet another characteristic of the invention, the spring comprises a bump intended to come to bear in the center of each lever, as close as possible to the pivot axis of the latter.

According to yet another characteristic of the invention, the lever reverse brake system comprises three levers.

According to yet another characteristic of the invention, in a synchronizer in which each push finger extends perpendicular to the lever and is engaged by its end opposite to that bearing on the friction ring in cutouts made in the two adjacent lever ends, the spring constrains the ends of the levers provided with the cutouts against the end of the push finger.

The motor vehicle is characterized in that it comprises such a synchronizer.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, made with reference to the appended drawings given solely by way of example illustrating a embodiment of the invention and in which:

- Figure 1 is a perspective view of a synchronizer equipped with a reverse brake system with levers and an anti-noise device according to the invention;

- Figure 2 is a sectional view along the line II-II of Figure 1;

- Figure 3 is a perspective view of the lever reverse brake system of Figure 1, provided with the anti-vibration device according to the invention;

- Figure 4 is another perspective view of the system provided with an anti-vibration device according to the invention, of Figure 2; and

- Figure 5 is a front view of the lever reverse brake system, provided with an anti-vibration device of Figure 2.

FIG. 1 shows a fifth gearbox synchronizer designated by the reference 1, which comprises a system 3 of reverse gear lever with levers 4, in the present case given by way of nonlimiting example, provided with three reversing levers 4 for reverse brake. This system is equipped with an anti-vibration device 5 which is designed to prevent the production of backlash and therefore of noise and vibration of the three levers.

The structure of the synchronizer 1 is known and described in detail in French patent no. 2,959,543 and its description which follows is therefore limited to what is necessary for the understanding of the invention.

The synchronizer to which the invention is applied by way of nonlimiting example, comprises a synchronization hub 7 which is integral in rotation with a receiving shaft (not shown) and provided with an internal toothing 8. The hub is axially interposed, as shown in particular in FIG. 2, between a stop plate 10 and a friction ring 12 intended to cooperate with a friction cone of a pinion idly mounted on the receiving shaft and engaged with an integral pinion of the motor shaft. The figures show neither the pinions nor the motor and receiver shafts which, on the other hand, are described in the aforementioned French patent. As can be seen in FIG. 2, between the hub 7 and the stop plate 10 is delimited a space 13 in which the three reversing levers 4 are arranged with the anti-vibration device 5.

The synchronizer 1 further comprises a synchronization sleeve 14 which is locked in rotation on the hub 7 and axially sliding under the effect of a control fork (not shown). Three arming blocks 16 are mounted axially sliding at the periphery of the hub 7 being angularly distributed at an angle of 120 ° from each other. Each block is pierced with a radial hole 17 in which is housed a ball 19 partially engaged in a recess 20 formed in the internal face of the sleeve 14, under the effect of the radial force of a spring not shown. Thanks to these retractable balls, the sleeve 14 can be fixed and detached from the blocks.

Regarding the levers 4, as can be seen in Figure 1, and in accordance with the aforementioned French patent, each has the shape of an arc of circle which cover an angular area of 120 ° so as to form together a crown coaxial with the axis of the synchronizer. Each lever has at its center a tongue 21 and its ends 22 are functionally connected to one end of two of the three push fingers 24, which pass through the hub 7 to come to bear on the adjacent front face of the friction ring 12. More precisely, as shown in FIGS. 3 and 4, the lever side end of each push finger comprises an annular zone 25 delimited between two flanges 26 and in which the two ends 22 of the two adjacent levers 4 engage. The ends are provided for this purpose each with a cutout 27 of complementary shape and compatible with the annular zone 25 engaged in these cutouts. On the other hand, each lever is supported along a line 29 on the internal face of the stop plate 10, which then constitutes an axis of pivoting or rotation of the lever. In accordance with FIG. 5, the pivot axis 29 of each lever 3 is parallel to a straight line between the end flanges 26 of the push fingers 24 to which the lever 1 is connected, passing at a place situated between the tongue 21 at the outer periphery of the lever and the bottom 31 of the internal face. As can be seen in FIG. 2, the tongues 21 of the levers bear on the adjacent front faces of the arming blocks 16.

With regard to the operation of the device for reversing brake levers with levers, it will only be recalled that, when shifting from reverse, when the sleeve 14 is moved by the control fork in the direction of the arrow F, the blocks then secured to the sleeve by the balls 19 are driven until they abut against the stop ring 10. During this movement, since they are in abutment on the tongues 21 of the levers, they make pivot these around their axis 29. This has the consequence that the ends 22 of the levers push the push fingers 24 against the friction ring 12 and the latter against the friction cone of the idler gear (not shown) thereby braking the rotation thereof relative to the shaft which carries it to immobilize the motor shaft, which allows the passage in reverse of the vehicle.

It should be noted that the reverse brake system is only functional when engaging reverse gear, as has just been described. But it is continuously driven on all gear ratios and for all engine speeds. The games necessary for its operation are likely to produce vibrations and noise from the levers. To overcome this drawback, the invention proposes to associate with this system the anti-vibration device which will be described below.

This anti-vibration device comprises in the example shown by way of nonlimiting example, a spring 33 in the form of a circular blade. The location of this spring is clearly visible in Figures 3 and 5. It is thus seen that the circular leaf spring 33 is arranged so as to be applied by its outer face against the radially internal faces 35 of the three levers. Consequently, the spring permanently forces the three levers radially against the push fingers. Advantageously, the spring is in point contact with each lever as close as possible to the pivot axis 29, that is to say at the bottom 31 of each lever. To this end, the spring has three bosses 37 each of which rests on the center 31 of each lever. This makes it possible to limit the friction and the yield losses of the levers which must be able to pivot and transmit the forces of the three arming blocks 16 on the three push fingers 24.

The spring applied against the internal faces of the levers is held axially between the synchronization hub 7 and the stop plate 10.

It emerges from the above description, that the circular leaf spring 33 due to the radial stress which it exerts on the reversing levers eliminates clearances 5 between the components and therefore noises and vibrations of the system reversing brake lever. The invention is presented here in its advantageous embodiment with three levers, but is also applicable to systems of another number of levers, for example with two levers.

Claims (7)

1. Gearbox synchronizer, provided with a reverse brake system (3) with levers (4), comprising at least two reversing levers (4) in the form of an arc of a circle, arranged so as to form a crown and interposed between a synchronization hub (7) and a stop plate (10) of the synchronizer, and which are in abutment on the abutment plate in order to be able to pivot thereon and in abutment by their ends (22) on at least two push fingers (24) which pass through the hub (7) to come to bear on a friction ring (12) of the synchronizer, characterized in that it comprises an anti-vibration device which comprises a circular spring (33) arranged coaxially with the crown of the levers (4) by bearing on the radially inner face of the latter so as to constrain the levers (4) radially against the push fingers (24). 2. Synchronizer according to claim 1, characterized in that the circular spring (33) is a leaf spring. 3. Synchronizer according to claim 2, characterized in that the spring (33) bears punctually on each lever (4) closest to the pivot axis thereof. 4. Synchronizer according to one of claims 2 or 3, characterized in that the spring (33) comprises a boss (37) for each lever (4), which is intended to come to bear on the central part (31) of the latter, as close as possible to the pivot axis (29) of the latter. 5. Synchronizer according to one of claims 1 to 4, characterized in that the lever reverse brake system comprises three levers (4). 6. Synchronizer according to one of claims 1 to 5, in which each push finger (24) extends perpendicular to the lever (4) and is engaged by its end opposite to that which bears on the friction ring (12) in cutouts (27) of two adjacent lever ends, characterized in that the spring (33) constrains the ends (22) of the levers provided with the cutouts (27) against the end of the push finger (24). 7. Motor vehicle comprising a synchronizer according to one of claims 1 to 6.