Abstract:
The invention relates to a synchronization device ( 2 ) for torque-transmitting components ( 4, 6, 8 ) of a transmission comprising a disk set ( 40 ) which has several disks ( 82 ) and a synchronizer sleeve ( 30 ) connected to a shifting device ( 64 ). The synchronizer system ( 2 ) has mechanisms ( 82, 84, 86, 88, 90, 92, 94 ) that divide the torque among the torque transmitting components ( 4, 6, 8 ) into an initial lower torque and a subsequent larger synchronizing torque. This is preferably achieved by a gradation of the disk ( 82 ) that enables a successive engagement of the disks on the torque transmission.

Description:
FIELD OF THE INVENTION 
     The invention relates to a synchronization device. 
     BACKGROUND OF THE INVENTION 
     Multi-step gear wheel transmissions are at present being practically exclusively used for transmitting the input power and adapting the motor torque to the traction requirement of a vehicle. 
     The shift system of the transmission can be considerably simplified with the aid of a synchronization device. In the synchronization, the rotational speed adaptation of the transmission components to be interconnected is carried out automatically or controlled in order to prevent double declutching during upshifts or double declutching with high switching of the throttle during downshifts. The traveling safety is clearly improved since the change of gears is quickly, safely and also noiselessly possible even under critical driving situations, e.g. when driving downhill the driver&#39;s right foot can remain on the brake during a downshift. 
     A synchronization system has the following tasks to perform: 
     rotational speed adaptation of two transmission components and the parts connected therewith that rotate at different speeds so that they can be interconnected with positive fit without grating noise; 
     locking of the positive-fit connection until synchronous speed of the transmission components to be connected is reached in order to prevent grating and damages of the positive-fit shifting components; 
     release of the lock at the moment of synchronous speed; 
     rotational speed adaptation within the shortest time and with the least possible shifting forces; 
     operational safety even under unfavorable circumstances such as in case of cold, viscous oil or of extremely quick breaking of the gears. 
     In the synchronized vehicle transmissions existing at present, synchronization devices for each separate gear are mostly used. 
     Lock synchronization with cones has been broadly extended at the same time. In this system, friction cones are used for the force-locking rotational speed adaptation of the transmission components to be connected. This kind of synchronization is used in the transmissions both of passenger cars and of industrial vehicles. 
     The customary synchronization devices make the three basic functions of the synchronization available: 
     often arbitrary lockable and releasable connection of two parts rotating around a common axis; 
     energy transmission to or energy drawing from a rotary part (acceleration, deceleration); and 
     adjustment of the rotational speed difference between two parts rotating around a common axis to a value equal to or near zero. 
     In synchronization systems with friction disks, the conical friction members are replaced by a number of disks which rub against each other during rotational speed compensation. In one version, disks axially abutting on each other in a sequence are connected with the synchronizer ring or the transmission shaft or, on the other hand, with the clutch body on the gear wheel or with the gear wheel itself. Such a synchronization system which, e.g. can also be equipped with a reinforcer device of the synchronizing force, has been disclosed in DE 32 08 945 A1. 
     From DE 195 06 987 A1 is known as a generic form fit gear clutch, the synchronizer sleeve of which is formed by an outer driver ring in which a shift fork engages, and by a shift hub which is non-rotatably but axially movably situated upon a synchronizer body. The shift hub carries selector teeth which interact with a dog clutch on a clutch body. The front faces of the selector teeth and the dog clutch are in corresponding revolution surfaces so that they bluntly strike on each other under axial shift movement. The clutch body is non-turnably but axially, elastically and flexibly connected with a gear wheel rotatably supported upon a transmission shaft. 
     Between the synchronizer body, non-rotatably connected with the transmission shaft, and the driver ring, is situated a slipping clutch in the form of a spring-loaded, lined multi-disk clutch, the driver ring being designed as an outer disk carrier and the shift hub as an inner disk carrier. On the front side of the shift, hub lids are mounted which, with radial play, extend toward the driver ring and between which the lined disks support themselves under the pressure of a corrugated spring. 
     The outer periphery of the driver ring carries a meshing gear which interacts with driver teeth of a driver which is connected with the gear wheel non-rotatably, but axially and elastically flexible. The teeth of the driver are narrower than the tooth gaps so that in the peripheral direction an abundant play is formed which facilitates meshing of the meshing gear during shifting. The front faces of the driver teeth and of the meshing gear are in a conical revolution surface so as to form an angle in the axial direction toward the peripheral surface and toward the front face of the driver. 
     If the synchronizer sleeve is moved from its neutral position in the shifting position direction, the meshing gear of the driver ring first comes into contact and engagement with the teeth of the driver so that a slipping torque is transmitted, via the lined disks, from the gear wheel to the transmission shaft. The torque depends on the number of disks, the radius of the disks and the force of the corrugated spring. The necessary time in order to produce the synchronous speed between the gear wheel and the transmission shaft is decisive. Locking surfaces on the driver teeth prevent the shift teeth of the hub part coming into contact with the dog clutch before an approximately synchronous speed has been reached between the gear wheel and the transmission shaft. 
     It is obtained through the front faces extending into the revolution surface of the driver teeth, of the meshing gear, of the dog clutch, and of the selector teeth, that torques produced by the transmission components to be coupled exert no reaction forces on the shifting force. In addition, due to the axial flexibility of the driver and of the clutch body, contact impacts on the driver teeth and dog clutch are softly trapped thus over the whole shift stroke, a relatively uniform shifting force results which improves operating comfort. 
     Internal disks are customarily coated on both sides while the outer disks are uncoated steel disks, but disks coated on one side can also be used. 
     Disk synchronization, according to the prior art, has the disadvantage that in the range of the meshing gear, wear can be found which is generated due to the impingement of the tooth front edges and front surfaces during full differential rotational speed. 
     The problem on which the invention is based is to reduce the wear in the area of the meshing gear. 
     SUMMARY OF THE INVENTION 
     The height of the meshing pulse directly depends on the friction torque of the disks. The lower the friction torque of the disks, the smaller is the pulse and the wear. It is proposed, according to the invention, to provide on the synchronization system means which, upon engagement, divide the torque transmitted among the teeth of the synchronizer sleeve and the teeth on the clutch body into an initial lower meshing torque and a subsequent larger synchronizing torque. 
     In an advantageous design, the means are formed by grading of the disks enabling a successive engagement of the disks of the synchronization system in the torque transmission. 
     Another advantageous embodiment shows the grading of the disks in a manner such that at least one first step is provided to form the meshing torque and at least one second step to form the synchronizer torque. 
     Another advantageous design on the first step has two friction surfaces to form the small meshing torque and on the second step ten friction surfaces to form the synchronizer torque. 
     In another advantageous embodiment, the step between the engagement of two successive disks is formed so that the shifting vibrations are reduced. 
     When the teeth move on the synchronizer sleeve in the direction of the teeth on the clutch body of a transmission part to be engaged, in the first step, the driver teeth of the disks grips only the edge of the synchronizer sleeve first, with at least one disk, in order to produce with the disk and appertaining friction surfaces a friction torque corresponding to a meshing torque. The build up of the meshing torque is earlier than the build up of the synchronizer torque proper, which should cause the approximation of rotational speed. Due to the prior meshing torque, the engaging torque stops are kept out of the synchronization system which would result if from the start the synchronization operation were begun with the full friction torque of all disks. Thus a practically easy pre-synchronization takes place followed by the real synchronization. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, is explained in detail with reference to drawings which show: 
     FIG. 1 is a representation of a disk synchronization system; 
     FIG. 2 is a side view in section; 
     FIG. 3 is a top view according to FIG. 2; 
     FIG. 4 is one other side view in section; and 
     FIG. 5 is a top view according to FIG.  4 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows the representation of the inventive synchronization device  2 . On a transmission shaft  4 , two gear wheels  6  and  8  are axially fixed, but freely rotatably situated. To that end, the gear wheels  6  and  8  are supported on bearings, such as needle bearings  10 , so that they can rotate as friction free as possible around the transmission shaft  4 . Between the gear wheels  6  and  8 , and upon the transmission shaft  4 , a synchronizer body  12  is placed which is non-rotatably connected, preferably via teeth  14 , with the transmission shaft  4 . Between the synchronizer body  12  and the gear wheel  6 , a clutch body  16  and a spring device  18  are provided. The spring device  18  is designed, e.g. as corrugated spring and cushions the clutch body  16  in the direction of the synchronizer body  12 . Between the synchronizer body  12  and the gear wheel  8 , a clutch body  20  and a spring device  22  are provided. The spring device  22  is also designed, e.g. as a corrugated spring and cushions the clutch body  20  in the direction of the synchronizer body  12 . The clutch body  16  has a dog gear  24  as outer toothing. The clutch body  20  also has a dog gear  26  as outer teeth. The synchronizer body  12  has an outer teeth  28  in which the synchronizer sleeve  30  by inner teeth engages. The synchronizer sleeve  30  with its inner teeth is axially movable in the outer teeth  28 . The inner teeth of the synchronizer sleeve  30  act as a dog gear  32 , together with the dog gears  24  and  26 , on the clutch bodies  16  and  20 . The dog gears  24 ,  26 ,  32  can be designed blunt, i.e. without sharp points. The ends of the dog gears  24 ,  26 ,  32  can be provided on the corners with rejecting bevels which prevents possible engagement at inadmissibly high rotational speeds. In addition, the taper rolling of the teeth of the dog gears  24 ,  26 ,  32  proves advantageous since a self-locking connection is obtained between the dog gears  32  of synchronizer sleeve  30  and the clutch body  16 ,  20 , which prevents an undesired tripping of the gears. Additionally, on its outer periphery, the synchronizer sleeve  30  has outer teeth configured in the shape of gripping tooth  62 , as explained in detail in FIG.  2 . In the outer periphery, a groove can be provided in which a shift fork  64  of a shifting device can advantageously engage. 
     The synchronizer sleeve  30  has an inner disk carrier  34  and an outer disk carrier  36 . The disk carrier  34  meshes, e.g. by outer teeth  38 , in corresponding teeth on separate disks of a disk set  40 . The disk carrier  36  for its part engages, e.g. by an.inner teeth  43 , likewise in corresponding teeth on other disks of the disk set  40 . At the same time, one disk connected with the disk carrier  34  follows in axial sequence upon one disk connected with the disk carrier  36 , whereby, when the disk carriers  34  and  36 , respectively, turn against each other, the disks of the disk set  40 , rub against each other. The friction surface of the disks preferably consists of paper, but other materials with favorable frictional properties, such as molybdenum friction linings or sintered friction linings, can be used. To obtain a small axial extension of the synchronizer sleeve, the number of disks must be limited, e.g. to three disks for each of the disk carriers  34  and  36 . By a spring device, such as a plate spring  42 , the disk set  40  is set in the axial direction under a defined prestress, the disk set  40  being pressed by the plate spring  42  against a first part  44  connected with the inner disk carrier  34 . The plate spring  42  abuts on the other side on a second part  46  and supports itself axially in relation thereto. The second part  46  is likewise connected with the inner disk carrier  34  in the form, e.g. of a rivet  80  diagrammatically shown here. Screw connections or an arrangement with pins and guard rings can also be used. The parts  44  and  46 , which can be designed, e.g. in the form of metal plates, are freely rotatable relative to the outer disk carrier  36 . On the gear wheel  6  is provided a gripping device  50  which is non-rotatably connected with the gear wheel  6  via inner teeth  52  by outer teeth  54  on the gear wheel  6 . In the outer teeth  54 , the gripping device  50  with its inner teeth  52  is axially movable with limitation. At the same time, the gripping device  50  is axially limited on one side by a stop on the gear wheel  6  and on the other side by a safety device such as a guard ring. Between the gripping device  50  and a stop on the gearwheel  6 , a spring device, such as a corrugated spring  58 , can be provided by which the gripping device  50  is axially cushioned relative to the synchronizer sleeve  30 . The gripping device  50  has gripping teeth  60  axially oriented in the direction of the synchronizer sleeve  30  which is explained in detail in FIG.  2 . The gripping teeth  60  are adapted to mesh in the gripping teeth  62  on the synchronizer sleeve  30 . 
     On the gear wheel  8  is provided a gripping device  66  which is non-rotatably connected with the gear wheel  8  via inner teeth  68  by ah outer teeth  70  on the gear wheel  8 . In the outer teeth  70 , the gripping device  66  with its inner teeth  68  is axially movable with limitation. At the same time, the gripping device  66  is axially limited on one side by a stop on the gear wheel  8  and, on the other side, by a safety device such as a guard ring  72 . Between gripping device  66  and stop on the gear wheel  8  can be provided a spring device, such as a corrugated spring  74 , by which the gripping device  66  is axially cushioned relative to the synchronizer sleeve  30 . The gripping device  66  has gripping teeth  76  axially oriented in the direction of the synchronizer sleeve  30  which is explained in detail in FIG.  2 . The gripping teeth  76  are adapted to mesh in the gripping teeth  62  on the synchronizer sleeve  30 . 
     The disk carriers  34  and  36  with the disk set  40 , together with parts  44  and  46  and the plate spring  42 , form a common axially movable homogeneous shifting set. To move the shifting set, an actuation element, such as the shift fork  64 , meshes in an externally circular recess in the outer disk carrier  36  of the synchronizer sleeve  30 . 
     If one of the loosely rotating gear wheels  6  or  8  should now be connected with a transmission shaft  4  having a different rotational speed, the homogeneous shifting set is moved in the direction of the gear wheel to be coupled. Due to the movement, the outer disk carrier  36  comes into contact with the gripping device  50 . The gripping device  50 , cushioned by the corrugated spring  58 , can axially turn aside the disk carrier  36 . In the areas where disk carrier  36  and gripping device  50  make contact, the two parts have gripping teeth  60 ,  62 . Due to the small bulk of the gripping device  50  and under the axially acting tension of the corrugated spring  58 , the gripping device  50  with the gripping teeth  60  will mesh at the adequate moment, i.e. when passing a tooth gap, in the gripping teeth  62  on the disk carrier  36 . By virtue of the meshing, the gripping device  50  can transmit a torque from the outer disk carrier  36  to the gear wheel  6  and vice versa. If the torque exceeds a limit value, adjustable by the number of disks and design of the plate spring or restraint of the plate spring, the disk set begins to slip. The use of paper disks is convenient here, since the difference between static friction and sliding friction can be kept low. 
     The existing differential rotational speed between the gear wheel  6 , the inert rotary masses connected therewith, and the transmission shaft  4  causes the torque that turns the friction disks against each other. A dynamic shock operation due to the sudden acceleration of inert rotary masses is prevented by the multi-disk clutch and confines itself only to the abrupt acceleration of the outer disk carrier  36  and of the friction disks connected therewith. The inventive construction makes it possible to keep the inert masses very small. The rotational energy contained in the freely turning inert messes during deceleration and the missing energy during acceleration are transmitted via the slipping multi-disk clutch. In this synchronization phase, the slipping multi-disk clutch takes over the function of rotational speed compensation. In this synchronization phase, the whole shifting set is further displaced in the direction of the gear wheel  6 . The shifting set is guided here into teeth  28 ,  32  between inner carrier  30  and synchronizer body  12 . After a defined displacement path, the dog gear  32  of the inner disk carrier comes into contact with the outer dog gear  24  on the clutch body  16 . The clutch body  16  can axially set aside the inner disk carrier  30  due to its cushioning by the corrugated spring  18 . 
     When the dog gears  24 ,  32  are designed with blunt ends, the blunt front faces are one upon the other probably more under prestress of the springs. If a meshing has accidentally occurred, the shifting operation is terminated altogether. Otherwise in the state of braced superposition of the teeth, the vehicle clutch becomes closed and the torque that builds up turns the teeth against each other. The teeth mesh and the gear shift is terminated. A premature turning of the teeth against each other and a subsequent meshing are also possible by slip torques on the wheel set of the transmission. 
     If, for example, the gear shift is not manually carried out by a driver by selector linkage, the alternative of an automatic gear shift is also possible by shifting means by remote control operated by the driver. The remote actuation is also possible with intercalation of a logical control which takes action on the shiftable gear steps. Without the driver&#39;s influence, an automatic system can also take over the whole gear shift of the transmission, the shift being preferably effected in the optimum ranges. 
     Pneumatically or electrically actuated shifting means are mostly used as shifting means. Hydraulically actuated shifting means can also be used. 
     By the elimination of the meshing slopes on the dog gears, a shorter shift stroke can be achieved. This gain in stroke can be used for enlarging the ratio between shift lever and synchronizer sleeve. The shift and selector strokes on the shift lever under small shifting forces thereby can be definitely reduced. 
     The cushioned superposition of the dog gears of the synchronizer sleeve and clutch body imparts to the driver an improved shifting feel and makes possible high rotational speeds when shifting. 
     The proposed synchronization system can be used to special advantage in automatic synchronization systems having a motor guide where by an engagement in the motor control. A defined differential rotational speed is always available here. In particular, a safe synchronization of the gear steps to be shifted can be obtained at very advantageous costs. The backlash of the torque-transmitting teeth is as low as possible. 
     A sufficiently long synchronization is needed in the disk set  40  before the dog gears  24 ,  26 ,  32 , provided for torque transmission, convert the free rotary masses from the friction coupling of the multi-disk clutch to the positive fit of the dog gears, in order to prevent a torque impact of inadmissible magnitude. This can be obtained with the inventive arrangement of the disks in the form of steps. 
     FIG. 3 shows a section through the disk set along the line  3 — 3  of FIG.  2 . The gaps between the tooth  84  on one side and the teeth  88 ,  90 ,  92  and  94  can easily be detected here. 
     In another advantageous design, FIG. 4 shows a section through the disk set  40  along the line  2 — 2  of FIG. 1 in another advantageous design. As a first step  104 , a first disk  82  with its tooth  84 , which extends into the synchronizer sleeve  30 , abuts with slight play on the edge  86  of the inner tooth  43  of the synchronizer sleeve  30 . The other teeth  88 ,  90 ,  92 ,  94  (FIG. 3) form other steps  106 ,  108 ,  110 ,  112  and opposite to the edge  86 , have gaps  96 ,  98 ,  100 ,  102  which increase from tooth to tooth. Thereby the teeth  88 ,  90 ,  92 ,  94  abut gradedly on the edge  86  only later than the tooth  84 . Thus the disk  82  with its friction faces can first transmit the meshing torque while the friction faces of the other disks are used only with graded delay to transmit the synchronizing torque. As soon as the gripping device  50  meshes in the gripping teeth  62  of the synchronizer sleeve  30  (FIG.  1 ), the tooth  84  abuts first on the edge  86  and transmits the meshing torque. Only after a delayed crossing of the gap  96 , the tooth  98  abuts on the edge  86 . After each crossing of another gap, the teeth  90 ,  92  and  94  abut on the edge  86 . Only after abutment of the tooth  94  on the edge  86  do all disks transmit the full synchronizer torque. 
     The smallest possible mass of gripping teeth and clutch bodies with a preferably cushioned arrangement creates dynamically favorable gripping and meshing mechanics in order to achieve a capture of the gear wheels at a high rotational speed difference and a reliable meshing in the respective opposing teeth with the least wear of the teeth. A rotary elastic arrangement in a peripheral direction to the gripping teeth can constitute a further improvement of the damping behavior during meshing of the gripping teeth. 
     The gripping teeth can also be disposed on the gear wheels so as to be rotatable on the gear wheels when a high, defined preset friction torque is exceeded, The friction torque is higher than the friction torque in the disk set. By turning, it is possible to dampen high impact peaks of the gripping teeth. 
     The use of friction disks with paper linings combined to form a set jointly usable for two gear steps creates an advantage in cost. These are also by far more environmentally compatible than, e.g. disks with molybdenum coatings. A disk whose static friction value is less than its sliding friction value constitutes an optimal solution in the process of disk configuration. 
     The elimination of a locking device likewise reduces the cost of the synchronization system aside from the prevention of all often arising locking problems.