Abstract:
To improve the safety of automated gearboxes, it is proposed that terminal positions of internal gearshift members and external actuation members be so defined separately from each other that one can recognize whether the engagement of a speed is accompanied by the attainment of a terminal position of an internal gearshift member or an external actuation member. Error analysis is possible in this way. For dual clutch gears, it is additionally proposed that one can, at least in gearshift operations that are critical in terms of safety, disengage on speed of a subgear in a separate procedure, before a new speed of this subgear can be engaged.

Description:
CROSS-REFRENCE TO RELATED APPLICATIONS 
   This application claims priority of German Patent Application No. 10 2004 042 424.1, filed Sep. 2, 2004, which application is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   This invention relates to a method for error recognition when switching an automated gearbox. The invention furthermore relates to a method for error avoidance when switching a parallel gearbox. In addition, the invention relates to an automated gearbox for the performance of the invention-based methods. 
   BACKGROUND INVENTION 
   Automated gear boxes are being used increasingly on account of the resultant comfort improvement, but above all, on account of possible of consumption savings in modern motor vehicles. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to improve the operational safety of such automated gearboxes. 
   A first solution of this problem is achieved for error recognition when switching an automated gearbox with switching members, inside the gear, for the switching gear speeds and an actuation device, outside the gear, with at least one actuation member for actuating the switching members, which at least one actuating member can be placed, by a selection actuator, in the engagement position, with at least one of the switching members, and which can be moved by a switching actuator for moving the particular switching member, in which method, one defines terminal switching positions that are assumed by the switching member with whatever speed is set and where terminal actuation positions are defined, up to which at the least one actuation member can be moved for the purpose of switching a speed, whereby the position of the switching member, defined by the terminal actuation position, lies outside the position of the switching member that is defined by the terminal switching member, thus acquiring the position that the switching member or the actuation member reaches when switching a speed and that depends on whether a terminal switching position, a terminal actuation condition, or none of the two of them is attained, one can diagnose an error state of the gear and/or of the actuation device. 
   According to the invention, a possible error is analyzed and associated by means of the acquisition of the terminal speed position when switching into a new speed and its association with a stop, inside the gear, or a stop outside the gear or located in the actor. 
   Advantageously, the position of the switching member—as defined by the terminal actuation position of the actuation member—assuming full use of possible tolerances, lies outside the position of the switching member as defined by the terminal switching position. 
   It is furthermore practical that the terminal switching positions of various speeds differ from each other. 
   Here it is particularly practical to design the terminal switching position of the reverse speed with a lesser interval from a neutral position than the terminal switching positions from the forward speeds. 
   Another solution to the problem inherent in the invention is achieved as follows: a method for error avoidance when switching a parallel gear box with two subgears with one, each, clutch, whereby as a result of the selective release of one of the clutches of one of the subgears, in a torque transmission path, between a drive motor and the driven wheels of a vehicle will take effect and at least one of the subgears will display at least one gear step of speed range, in which two speeds can be switched, in which method, one drives with one speed of the at least one switching way of the one subgear, and where, during this driving, in case of switching actions that are critical in terms of safety prior to the engagement of the other speed of the at least one switching way, the one speed of this gear step of speed range, with which the car was driven before, is disengaged in a working step separate from the engagement. 
   The invention-based method makes it possible to ensure that, in case of switching actions that are critical in terms of safety, for example, in switching actions after a prior change in the direction of movement, dangerous operating states can be avoided. 
   The above mentioned method is used, for example, in parallel gearboxes, where an actuation device is provided, with one, each, main actuation members and secondary actuation members, associated with the subgear, whereby the main actuation members are provided for moving a particular subgear of the switching for engaging a speed and the secondary actuation members are provided for moving a particular subgear, corresponding to the particular other one of the switching members, for disengaging a speed, a selective actuator for moving the main and secondary actuation members toward different gear step of speed range of the subgears and a switching actuator for moving the main actuation and secondary actuation members for engaging or disengaging a speed, in which method, prior to the engagement of a speed of a subgear, with the help of a main actuation member, the pertinent secondary actuation member, by means of the selective actuator, is moved into the gear step of speed range belonging to the speed and where an engaged speed of the gear step of speed range is disengaged by moving the secondary actuation member with the help of the switching actuator. 
   Preferably, the method is applied when a reverse speed and a second forward speed are arranged in a first switching gear step of speed range of a subgear and a first forward speed belongs to a gear step of speed range of the other subgear, in which method, after driving in reverse and after subsequent driving forward, in the first speed, prior to the engagement of the second speed, the speeds of the first gear step of speed range are disengaged. 
   An automated gearbox for the performance of the invention-based method contains switching members, inside the gear, for switching the speeds of the gear, an actuation device, outside the gear, with at least one actuation member for the purpose of actuating the switching members, which at least one actuating member can be moved, by a selection actor, into the engaged position with at least one of the switching members and where a switching actuator can be moved for the purpose of moving the particular switching member, whereby the terminal switching positions are defined, which are the positions that the switching members assume with the particular connected speed and where terminal actuation positions are defined up to which the at least one actuation member can be moved for the purpose of switching a speed, whereby the position of the switching member, defined by the terminal actuation position of the actuation member, lies outside the position of the switching member as defined by the terminal switching position, with sensor devices for acquiring at least the terminal positions of the switching members and the position of the actuation member and an electronic control device for controlling the actuators and for utilizing the output signals of the sensors in accordance with one of the above mentioned methods. 
   The invention, which can be used in the most widely differing vehicles with the most widely differing driving modes and driving engines and the most widely differing automated gearboxes, is explained below with reference to diagrams by way of example and with other details. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The figures show the following: 
       FIG. 1  is a diagram of a known actuation device for an automated gearbox; 
       FIG. 2  is a circuit diagram of an automated gearbox with an illustration of the terminal actuation positions; 
       FIG. 3  is a diagram of a known parallel gearbox; 
       FIG. 4  is a part of an actuation device for a parallel gearbox, shown in a perspective view; and, 
       FIGS. 5 through 7  are circuit diagrams to explain an invention-based method. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   According to  FIG. 1 , a known automated gearbox, not shown, includes a device with switching members, inside the gear, and an actuation device, outside the gear. The switching members, inside the gear, in the example illustrated, contain two mutually parallel movably arranged sliding selector shafts  10 ,  12  with one, each, gear shift fork  14 ,  16 , and a gearshift block  18 ,  20 , with a recess  22 ,  24  on the top. 
   Provided for engagement in a particular one of the recesses  22 ,  24 , is a gearshift finger  26  that, by means of a selection actuator  28 , can be moved in a Y direction, laterally to the direction of mobility of the sliding selector shafts  10 ,  12 , and that can be moved, with a gearshift actuator  30 , parallel to the movability direction of the sliding selector  10 ,  12 , The gearshift finger  26  is attached in the known manner for example upon a rod that is movably and swingably attached upon a housing of the gear, which rod can be moved with the help of the selection actuator  28  and that can be rotated with the help of the gearshift actuator  30  around its longitudinal axis. 
   The gear shifting is so done that the gearshift finger  26 , which, after the actuation of the selection actuator  28 , is in one of the recesses  22 ,  24 , according to the figure, for example, is shifted or swung to the left, whereby the pertinent gearshift fork moves a clutch sleeve that is attached upon a gear shaft and engages a speed. In a further gearshift operation, this speed is disengaged in that the corresponding gearshift block, by moving the gearshift finger  26 , is moved back into the selection gear step of speed range and thereafter, depending upon the speed that is to be set, is moved out of the selection gear step of speed range for the purpose of inserting the “opposite” speed with the help of the same clutch sleeve or, where, first of all, from the particular gearshift block, along the selection gear step of speed range (Y direction) is made to engage the neighboring gearshift block (neighboring gear step of speed range) and a speed will be set in that gear step of speed range. 
   Stops  32 ,  34 ,  36 , and  38  are provided for the switching device, inside the gear, for the purpose of monitoring the function of the actuation device, and these stops limit the movability of the sliding selector shafts or of the gearshift blocks, rigidly connected into therewith, one or the other X direction. Their attainment is detected for instance in the sudden rise of the power consumption of the selection actuator or by the latter&#39;s standstill or directly by correspondingly positioned to terminal switches. The gearshift actuator is turned off when a terminal gear shift position, defined by the stops, is acquired. 
   The movability of the gearshift finger  26  in the X direction, by means of the switching actuator, is limited by the stops  42 ,  44 . These stops  42  and  44  can be mechanical stops, possibly provided with terminal switches. They can also be “electronic stops” that can be formed by a motion sensor or an increment counter, that acquires the actuator position  30  and that is referenced in predetermined, marked positions, so that the actuator position will be absolutely known. Reaching the stops  42  and  44  is acquired by the control device  40  and results in the termination of the movements of the gearshift finger  26  into the particular X direction upon the attainment of the stop. 
     FIG. 2  illustrates the conditions with reference to a circuit diagram. Y-Y refers to the selection four gear step of speed range. Perpendicularly thereto extend four gear steps of speed range (X direction and  FIG. 1 ), whereby only one speed can be set in the two outer gear steps of speed range. The solid stop lines  46  at the end of each gear step of speed range designate the terminal switching positions of the gearshift forks, defined by the stops, or parts of the gear connected rigidly therewith. The broken stop lines  48 , that are further removed from the selection gear step of speed range than the stop lines  46 , designate the terminal actuation positions of the actuation device that is outside the gear, that is also defined by mechanical stops, or as explained earlier by electronic stops. 
   The circled segment in  FIG. 2  shows the tolerance bands of the particular terminal positions; here one can make sure that the tolerance band—associated with the stop line  48 —of the terminal actuation position of the actuation device (actuator  30 ), outside the gear, will lie completely outside the tolerance band, within which lie the stops for the gearshift members outside the gear. The interval between the two tolerance bands is labeled a. 
   A positive measure a, for example, in the millimeter range, must also be guaranteed, considering the elasticities, the leeways, the temperature expansions and the wear and tear throughout the service life for all of the terminal speed positions. It goes without saying that the measurement accuracy must be considered here, that is to say, the accuracy with which one acquires the position of the gearshift actuator  30 , for example, by means of an increment counter. 
   During routine operation, control device  40 , when engaging a speed, must acquire a terminal gearshift position that is defined by one of the internal stops ( 32 ,  34 ,  36 ,  38  in  FIG. 1 ) or by a stop line  46 . These terminal positions are stored in a memory of the control device  40 . They are recognized, for example, in that the actuator current increases suddenly or that the actuator comes to a halt. 
   If a terminal gearshift position is exceeded when engaging a speed and when the terminal position, attained upon the engagement of its speed, in the tolerance band  48 , lies in the terminal actuation position or is defined by one of the stops  42 ,  44 , this points to a rupture or a deformation in the internal gear shifting. Such a defect can be reported to the driver in which connection one can activate an emergency operation in that one heads for a repair shop when, for example, a different speed can still be engaged without any trouble. 
   When the gearshift actuator, upon engagement of a speed, moves the gearshift finger  26  or a position going beyond the tolerance band  48 , so that no stop is acquired, this points to an error in the incremental path measurement or to a rupture in the external actuation device. There is then an error message including the fact that the system will be turned off. 
   When, upon the engagement of a speed, the gearshift actuator  30  comes to a halt outside a position defined by the stops  42  and  44 , this can be due to a deformation or a rupture of the actuation device, outside the gear, or the internal gearshift in the gear or an error in incremental path measurement. This is followed by a corresponding error message and a system turnoff. 
   Specifically targeted error diagnosis is thus possible with the help of the described, mutually independent acquisition of the terminal switching positions, inside the gear, and the terminal actuation positions, outside the gear. Furthermore, an emergency run can be activated in certain states so that the system will not have to be turned off unnecessarily. 
   Differing terminal switching positions or stops can be associated with the individual speeds. When the terminal switching position of the reverse gear for example is closer to the selection gear step of speed range then the terminal switching positions of the forward speeds, then one can make a differentiation between the reverse speed and the forward speed, without having to acquire the particular selection position. The reverse speed can in this way be recognized reliably and quickly as a result of which a clutch, not illustrated, can be released earlier and the speed change can be completed faster. 
   The method, described here by way of example, can be applied to the selection mechanism in that there are provided stops inside the gear and outside the gear, for example, to limit the movability of the gearswitch finger, in the direction of selection. 
   The described method can be used both for a conventional automated gearboxes with merely one clutch, where, during a speed change, there is an interruption in the traction force and in parallel gearboxes, where the speed change can be accomplished without any interruption in the traction force. 
     FIG. 3  shows the basic structure of such a known parallel gearbox.  FIG. 4  shows a part of an actuation device for such a parallel gearbox. The figures are taken from DE 102 06 561 A1 where the operating mode and the actuation of parallel gearboxes are explained in detail. 
   Between a drive motor  60  and a drive  62 , leading to the driven wheels of a vehicle, there are formed two power trains  64  and  66 , via which the flow of moments can take place. Associated with each power train is a clutch  68  or  70  and a subgear  72  or  74 . 
   Actuation devices for clutches are labeled  76  or  78 . Actuation for subgears  72  or  74  are labeled  80  or  82 . 
   Translation steps, between which change without traction force interruption should be possible, are associated with different subgears. For example, speeds 1, 3, and 5 belong to one of the subgears and speeds 2, 4, 6, and R belong to the other subgear. 
     FIG. 4  shows parts of an actuation device that is commonly shared by the two subgears  72  and  74  (which actuation device combines the actuation device  80  and  82  in  FIG. 3 ). 
   Clutch sleeves  101 ,  102 ,  103 , and  104 , connected in a non-rotary manner with shafts of the subgear  72 ,  74 , not shown, are moved by gearshift forks  105 ,  106 ,  107 , and  108 . The clutch sleeves  101  and  104  are associated with one of the subgears. The clutch sleeves  102  and  103  are associated with the other subgear. The external actuation device contains a first main actuation member  111  in the form of a gearshift finger and an additional main actuation member—not visible in FIG.  4 —by means of which one can engage speeds. Furthermore, secondary actuation members  113 ,  116  are provided which make sure that, in each case, all other speeds of the same subgear are disengaged. The gearshift forks  105 ,  106 ,  107 , and  108  can be moved axially on shafts  109  and their mouths are so designed that they will each time come to engage a main actuation member  111  (gearshift finger) or secondary actuation member  113 ,  116  that is made in the form of a dual cam. For this purpose there are provided first subsections  114  for connection with a main actuation member  111  and second subsection  115  with a secondary actuation member  113 . To engage a speed, for example, main actuation member  111  will connect up with a terminal section  110  corresponding gearshift fork  105  or  106 , in that a gearshift shaft  112 , provided with the actuation members, is shifted in the axial direction by a selection actuator. 
   At the same time, the secondary actuation member  113  establishes contact each time with the corresponding gearshift fork  107  or  108  which belongs to the same subgear. A rotation of the gearshift shaft  112  by means of a gearshift actuator will swing the main actuation member  111 , by means of the gearshift fork  105  or  106  upon shaft  109  and thus also the pertinent clutch sleeve  101  or  102  is also shifted and the corresponding translation step is engaged. At the same time, the turning of the secondary actuation member  113  will cause the disengagement of the corresponding speed if the latter is engaged. For the actuation device according to  FIG. 4 , one can define terminal actuation positions that are similar to those explained with reference to  FIGS. 1 and 2 . 
   Here is a problem encountered in a dual clutch gear, such as it was described with reference to  FIGS. 3 and 4  and such as it is known: 
     FIG. 5  shows a circuit diagram of such a dual clutch gear, where the perpendicular line designates the selection gear step of speed range. No speed is set when the main actuation member (gearshift finger) is in the selection gear step of speed range, that is to say, the gear is in neutral (N) and the switching shaft can be moved by the selection actuator between the individual gear shift gear steps of speed range that are illustrated horizontally. When the gear shaft is turned into one or the other direction by the gearshift actuator, when a main actuation member is in one of the gearshift gear steps of speed range, then the specified speeds are connected. Here, speeds R, 2, 4, and 6 are associated with one subgear and speeds 1, 3, 5, and 7 are associated with the other subgear. 
   In the following we will explain a known gearshift procedure with reference to the arrows in  FIG. 5 , which indicate the movement of the main actuation member. Starting with the neutral position, the main actuation member connects the reverse speed R; then we move back to neutral and we switch back to the other subgear, in which the first speed is engaged from neutral. This can be done while the vehicle is running backward. Afterward this procedure, the main actuation member is moved to neutral and once again there is a change in the gear step of speed range to the other subgear. After the reverse run has been completed, the gear control will release the clutch for the odd subgear and one can drive forward. As of that point in time, the power train to the even subgear is disengaged and one can connect the second speed. 
   By way of a potential error possibility, as the first speed is engaged, the flow of force to the main actuation element could be broken but the first speed can still be completely engaged when, for example, after the engagement of the first speed, the main actuation member (gearshift finger) wears out or breaks. When the gear is not equipped with the two terminal position limits (inside the gear and outside the gear) according to  FIG. 2 , but rather only with the terminal position recognition or limitation, outside the gear, then, after such an exemplary rupture or wear of the gearshift finger, the gear control would start from the assumption that the second speed was properly engaged, when the stop, outside the gear, or the selection actuator inside the gear, was recognized as a gearshift path limitation. Actually, the R speed would then always still be engaged in the even subgear. The previously mentioned error is not acquired by the gear control; therefore, the clutch for the even subgear would be released. At that instant, depending on the driving situation, there could be some very dangerous consequences, for example, one could start up in the wrong direction, the wheels could be locked, or the gear could be destroyed. 
     FIG. 6  shows a gearshift procedure intended to solve the above mentioned problem. 
   The reverse speed R and the first speed are engaged as explained in reference to  FIG. 5 . Subsequently, however, the main actuation member is moved to the gearshift gear step of speed range 6/4 that belongs to the same subgear as gear step of speed range 2/R. In that position, the gearshift shaft is moved, with the main and secondary actuation members, by way of a rotation angle that corresponds to a disengagement movement. The prerequisite here is that the flow of force exists to the secondary actuation element. Subsequently, the main actuation member is set on neutral and is moved into the gear step of speed range 2/R. There, one now tries according to plan to engage the second speed. 
   The core of the invention thus is, in coping with potential speed settings in terms of safety, first of all, to move the secondary actuation element into the gear step of speed range that is to be set and to disengage the speeds that are connected there. Subsequently, the main actuation member is moved into the gear step of speed range that is to be set and the gearshift operation as provided is performed. 
   The prescribed safety switching operation is performed especially when the direction of vehicle movement is changed; but it can also be performed when the gearshift settings are different, where, in case of a failure of the main actuation member, which is described by way of example above, a dangerous gearshift state can occur. 
   As an alternative to the described method, where a disengagement action can also be performed first in a gear step of speed range of the same subgear, one can, as shown in  FIG. 7 , start for a neutral disengagement gear step of speed range A, which, among the gear steps of speed ranges of a subgear, has an interval similar to the interval between the gear step of speed ranges of a subgear among each other. The disengagement gear step of speed range must thus be compatible with the “active interlock” that is achieved by the cooperation of the main actuation members and the secondary actuation members. 
   This neutral gear step of speed range, on account of its limitation, would permit only gear shift angles that correspond to the disengagement path of a speed. 
   List of References 
   
     
       
             
             
             
             
           
         
             
                 
             
           
           
             
               10 
               sliding selector shaft 
               68 
               clutch 
             
             
               12 
               sliding selector shaft 
               70 
               clutch 
             
             
               14 
               gearshift fork 
               72 
               subgear 
             
             
               16 
               gearshift fork 
               74 
               subgear 
             
             
               18 
               gearshift block 
               76 
               actuation device 
             
             
               20 
               gearshift block 
               78 
               actuation device 
             
             
               22 
               recess 
               80 
               actuation device 
             
             
               24 
               recess 
               82 
               actuation device 
             
             
               26 
               gearshift finger 
               101 
               clutch sleeve 
             
             
               28 
               selection actuator 
               102 
               clutch sleeve 
             
             
               30 
               gearshift actuator 
               103 
               clutch sleeve 
             
             
               32 
               stop 
               104 
               clutch sleeve 
             
             
               34 
               stop 
               105 
               gearshift fork 
             
             
               36 
               stop 
               106 
               gearshift fork 
             
             
               38 
               stop 
               107 
               gearshift fork 
             
             
               40 
               control device 
               108 
               gearshift fork 
             
             
               42 
               stop 
               109 
               shaft 
             
             
               44 
               stop 
               110 
               terminal section 
             
             
               46 
               stop line 
               111 
               main actuation member 
             
             
               48 
               stop line 
               112 
               gearshift shaft 
             
             
               60 
               drive motor 
               113 
               secondary actuation member 
             
             
               62 
               power takeoff 
               114 
               subsection 
             
             
               64 
               power train 
               115 
               subsection 
             
             
               66 
               power train 
               116 
               secondary actuation member