FR2687198A1 - SYNCHRONIZATION DEVICE FOR SWITCHING CLUTCHES, IN PARTICULAR IN GEARBOXES. - Google Patents

Abstract

The invention relates to a synchronization device arranged to facilitate the engagement of the teeth with one another. The inner toothing of a sliding sleeve (2), arranged to be selectively engaged with the outer toothing (8) of a coupling element (5), comprises an engaging toothing (9) and a locking tooth ( 10) which have different diameters and which are axially offset from one another. The locking toothing (10) cooperates with an external toothing (7) of a synchronization ring (4) and only allows the sleeve (2) to slide when the ring (4) and the coupling element (5) ) rotate at the same speed. The angles of obliquity of the ends of the teeth may be different on the two teeth (9 and 10). Application to switching clutches, in particular in gearboxes for motor vehicles.

Description

SYNCHRONIZATION DEVICE FOR CLUTCHES OF

  SWITCHING, IN PARTICULAR IN GEARBOXES

  The present invention relates to a synchronization device for switching clutches, particularly in gearboxes for motor vehicles, comprising a sliding sleeve provided with an internal toothing and capable of being secured in rotation with a shaft by axial sliding, a coupling element provided with an external toothing, as well as a synchronizing ring which co-operates positively in the circumferential direction with the sliding sleeve by means of external toothing and by friction with the coupling element, the toothing of the sliding sleeve having engagement and locking teeth which allow engagement in the external toothing of the coupling element only at synchronous speeds of said member and the sleeve.

  A device of this type is described in DE-B-2 659 448.

  This known device is arranged either to shorten the stroke at the actuated end of the control lever, or to increase the gear ratio of the lever without changing its stroke. This way, a greater force will be available on the sliding sleeve for synchronize by exerting the same force on the lever, or you will have to exert less force on the lever

  to get the same force on the sleeve.

  DE-B-2 659 448 proposes for this purpose to axially extend the teeth of the sliding sleeve in the direction of the coupling element, at least at two points of the circumference of the sleeve. only in the areas of the sleeve where the teeth are not extended. This arrangement also has the effect of shortening the engagement stroke to a degree equal to the extension of the locking teeth.

teeth of the sleeve.

  It has now been discovered that during the synchronization process, a difference in speed reappears, after the unlocking process, between the idler wheel to be synchronized and the sliding sleeve integral in rotation with the driven shaft. This comes from two causes, namely: a part rotation of the synchronizing ring and therefore also of the idler wheel with respect to the sleeve during the unlocking process and, secondly, the torque dissipated in the box, acting on the transmission members

  located on the clutch side and released after unblocking.

  The effects of the two aforementioned causes accumulate positively or negatively depending on the direction of the gear change. The differential speed due to the dissipated torque depends primarily on the

  value of the dissipated torque and the duration of the switching process.

  This is why the known synchronizers with internal cone have what are called "second points" during switching, when the sliding sleeve engages in the external toothing of the coupling element. "are felt by the driver in the form of a perceptible resistance shortly before the

end of shifting.

  In known synchronization devices, the engagement angle of the sliding sleeve is also the locking angle, which is defined by the data relating to the safety lock. This generally results in a locking angle of about 1150 at the moment. of engagement, this relatively obtuse angle has the disadvantage that the engagement force produces a relatively small tangential component Engagement can be easier or more difficult depending on the loss values that are specific to the box concerned. Therefore, the object of the present invention is to create a synchronization device of the kind indicated in the preamble and arranged to facilitate engagement of the teeth, with a simple construction and constructive dimensions unchanged for

the essential.

  According to the invention, this object is fulfilled by the fact that the internal toothing of the sliding sleeve comprises an engagement toothing and a locking toothing which are distinct and have different diameters. Thanks to the mutual separation of the two teeth according to the invention, these can each be optimally and independently adapted to the respective conditions. This means in particular that the switching process and in particular the engagement can

be facilitated.

  A particular advantage of the solution according to the invention is that the device can be made with the same dimensions as the known synchronization devices and can therefore be used in their place In comparison with synchronization devices constructed differently, such as for example the external cone synchronizers, the present invention, using synchronizers to

  inner cone, leads to a smaller width of the assembly.

  According to a very advantageous improvement of the invention, it is provided that the teeth of the engagement toothing are offset axially with respect to the teeth of the locking toothing. This arrangement is particularly advantageous as regards the geometry of the locking and the mode of engagement. of usual construction It can then be expected that the engagement teeth is shifted axially towards

  the outside of the sleeve relative to the locking toothing.

  Another advantageous aspect of the axial offset of the engagement toothing relative to the locking toothing is that this axial offset corresponds at least approximately to the axial thickness of the coupling element and determines a limitation of the stroke. of the sleeve by abutment of the locking toothing against said element Indeed, with the solution according to the invention, the surfaces of

  sliding sleeve can be radially

  below the hoop of the toothing of the coupling element, which then constitutes an end stop that prevents the

  sleeve to go further and therefore limit the engagement stroke.

  Preferably, the engagement toothing has a larger diameter

than the locking toothing.

  In an advantageous embodiment, the engagement toothing and toothing by a local elevation of the teeth local elevation is preferably

median of the sleeve.

  The difference in locking diameter is formed by the said sleeve in an axial zone. The teeth of the engagement toothing preferably have, at one axial end, an engagement angle of between 900 and the teeth of the locking toothing preferably have , at

  an axial end, a locking angle of at least 110.

  Other features and advantages of the invention will become apparent hereinafter

  below in the principle description of an exemplary embodiment,

  with reference to the drawings, in which: FIG. 1 is a view in axial section of a synchronization device of a known type, FIG. 2 is an axial sectional view of the synchronization device according to the invention, of FIG. is a sectional view of the sliding sleeve of the device according to the invention, with separate teeth for engagement and locking, Figure 4 schematically shows synchronization at the blocking stage, Figure 5 schematically shows synchronization at the engagement stage Figure 6 shows schematically the process of synchronization at the engaged stage, and of

2687198

  FIG. 7 is a partial view of the synchronization device

  following the arrow A of Figure 2.

  In outline, the synchronization device is of a known type and it also works in a known manner, which is why we mention below only the elements playing a role in the invention. essential elements of a known synchronization device are shown in Figure 1 in order to show very clearly, in comparison with the

  description and the following drawings and in particular Figure 2, the

  differences with respect to the embodiment of the invention.

  A guide sleeve 1, sometimes called a synchronizer hub, is non-rotatably mounted on a drive shaft, not shown. Due to a toothing provided on the periphery of the guide sleeve, a sleeve 2 is mounted to slide axially on the latter and also comprises a corresponding toothing on its inner periphery On both outer end faces of the sleeve of the synchronization device according to the state of the art, shown in FIG. 1, there is a combined toothing 3 of engagement and blocking device which can be made to cooperate in a known manner with a corresponding synchronizing ring 4 and a coupling element 5 Each coupling element 5 is rotationally integral with a non-idle wheel

represented.

  When idling, the sliding sleeve 2 is in the middle axial position. The idle wheels (not shown) can freely rotate on their shaft. The speed difference between the synchronizing ring 4 and the coupling element 5 as well as the torque residual between their friction surfaces that the synchronizing ring 4 usually rests against a rotational stop provided on the sleeve The biased front surfaces of the teeth of the

  sleeve 2 and the ring 4 are opposite each other.

  During switching, the sleeve 2 is slid in the direction of the corresponding coupling element 5

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  front teeth then ensure the transmission of the engagement force of the sleeve 2 directly to the corresponding synchronization ring 4 As long as there is a difference in speed between the ring 4 and the corresponding coupling element 5, the torque of friction on the conical friction surfaces 6 of the ring 4 and the element 5 is larger than the

  return torque passing through the biased front surfaces of the teeth.

  That's why sleeve 2 is still stuck and can not

  engage in the coupling element 5.

  It is only when the speed difference between the ring 4 and the element 5 has been canceled that the friction torque disappears and the sleeve rotates the ring 4 back to a position where their teeth are opposite the By passing through the locking toothing 7 of the ring 4, the sleeve 2 then continues to slide and engages in the toothing 8 of the element 5, whose

  frontal surfaces are also angled.

  On the other hand, in the construction according to the invention, as can be seen in particular in FIGS. 2 and 3, the engagement and locking functions fulfilled by the toothing of the sliding sleeve 2 are separated from one another, the toothing being In order to differentiate the teeth thus, the locking toothing is formed by raised parts of the teeth of the sleeve 2, in the outer frontal zones of the sleeve, in radially and axially outer positions with respect to the locking toothing. In practice, the sleeve 2 has in its middle part a ring of protruding teeth towards the inside, the front faces of which are axially indented with respect to those of

engagement teeth 9.

  The axial displacement or offset of the locking toothing 10 corresponds at least approximately to the thickness of the coupling element at the sliding sleeve 2, whose engagement path

  can then be limited by abutment of the toothing 10 against the element 5.

  Because the engagement toothing 9 and the locking toothing 10

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  are distinct, it is possible to optimally choose the angles between the biased surfaces of the ends of their teeth to adapt to their respective function For example, we can give a commitment angle a (Figure 4) between 90 and 950 to the teeth of the engagement toothing, while the locking angle 3

  teeth of the locking toothing may be at least 1100.

  In Figure 7 which shows schematically the synchronization device seen laterally along the arrow A of Figure 2, we see the mutual positions and the matches between the different teeth This figure also shows a spring loaded push rod 11 serving, in known manner, to synchronize the sleeve

sliding 2.

  The operation of the synchronization device will be described below.

  FIG. 4 schematically represents the position of the different parts of the synchronization device in a locking position. FIG. 5 represents the position of the parts during engagement and FIG. 6 represents the engaged state. center of each of Figures 4 and 5 is

  a partial developed view of the teeth.

  In the example illustrated in FIG. 4, the sleeve 2 has been slid to the right in order to switch, for example the engagement of a speed in a gearbox. To begin with, the locking toothing of the sleeve between in contact with the locking toothing 7 of the synchronizing ring 4 (see also FIG. 2) The outer diameter of the synchronizing ring 4 is chosen so that the engagement toothing 9 of the sleeve can pass over the ring 4 In other words, the teeth of the toothing 9 of the sleeve 2 are radially sufficiently outwardly relative to the teeth of the toothing 10 to pass outside the ring 4. As a result, the coupling element 5 has, at its teeth 8, a larger external diameter than the synchronizing ring 4, so that the teeth

  9 of the sleeve 2 can engage in the toothing 8 of the element 5.

  As long as there is a difference in speed between the ring 4 and the element 5, the engagement of the sleeve 2 on the element 5 is still blocked. Only when these two parts rotate at the same speed as the engagement the sleeve 2 can be done, its toothing 9 engaging in the toothing 8 of the element 5, which completes the switching process The engagement is facilitated by the more pronounced bias of the end faces of the teeth of the toothing 9, so that the "second point", i.e., resistance or increase in engagement force, does not exist or is not clearly

perceptible.

  In the views developed in the middle of FIGS. 4 and 5, it is also seen that three teeth are missing in the locking toothing 10 of the sleeve 2, in order to leave room tangentially for the synchronization pushbutton. This gap of three teeth is repeated three times. times on

  around the sliding sleeve 2.

  The present invention is not limited to the embodiment described above, but it extends to any modification or variant

obvious to a person skilled in the art.

Claims (8)

  Synchronizing device for switching clutches, particularly in gearboxes for motor vehicles, comprising a sliding sleeve provided with an internal toothing and capable of being fixed in rotation with a shaft by an axial sliding, an element of coupling provided with an external toothing, as well as a synchronizing ring which cooperates positively in the circumferential direction with the sliding sleeve by means of external toothing and by friction with the coupling element, the toothing of the sliding sleeve having teeth of engagement and locking which allow engagement in the external toothing of the coupling element only at synchronous speeds of said element and the sleeve, characterized in that the internal toothing of the sliding sleeve (2) comprises a set of teeth. engagement (9) and a locking toothing (10) which are   distinct and have different diameters.   Device according to claim 1, characterized in that the teeth of the engagement toothing (9) are offset axially relative to each other.   to the teeth of the locking toothing (10).   3 Device according to claim 2, characterized in that the engagement toothing (9) is axially offset outwardly of the   sleeve (2) with respect to the locking toothing (10).   4 Device according to claim 2 or 3, characterized in that the axial offset of the engagement toothing (9) corresponds at least approximately to the axial thickness of the coupling element (5) and determines a limitation of the stroke of the sleeve (2) per stop of   the locking toothing (10) against said element (5).   Device according to one of claims 1 to 4, characterized in that   that the engagement toothing (9) has a larger diameter than the locking teeth (10).   Device according to one of Claims 1 to 5, characterized in that 2687198   the difference in diameter of the engagement toothing (9) and the locking toothing (10) is formed by local elevation of the teeth of the sleeve (2).   7 Device according to claim 6, characterized in that said local elevation is in a central axial zone of the sleeve (2).   8 Device according to one of claims 1 to 7, characterized in that   that the teeth of the engagement toothing (9) present, at a   axial end, an engagement angle of between 900 and 95.   9 Device according to one of claims 1 to 8, characterized in that   that the teeth of the locking toothing (10) have, at a   axial end, a locking angle of at least 110.