DE102004013506A1 - Method for operating a drive train for a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a drive train with a toroidal continuously variable transmission, which has two stepless driving ranges and two constant gears (direct gear, synchronous gear). DOLLAR A Usually, the aforementioned driving ranges and gears are assigned to concrete drive situations such as speeds of the motor vehicle. DOLLAR A According to the invention, a method is proposed, according to which depends on operating parameters - for example, for vehicle speeds, a load request by the driver and / or a slope of the route - made a choice between a direct gear and a driving range and the transmission is suitably controlled. In this case, maps (80) are used in a control unit. DOLLAR A stepless transmission for motor vehicles.

Description

The The invention relates to a method for operating a drive train for a Motor vehicle with a transmission with a continuously variable driving range and a constant transmission gear according to the preamble of the claim 1.

From the publication EP 0 003 408 B2 For example, a transmission is known in which two different power paths are possible between an input shaft and an output shaft, firstly via a stepless belt variator and secondly via a clutch which connects the input side of the belt variator to a gear stage which drives the output shaft. Further switching elements make it possible to drive in different driving ranges while using the continuously variable adjustment of the belting variator. The use of the direct gear should increase the range of possible gear ratios and increase the efficiency of the transmission, since in the direct gear power losses through the use of the looping variator do not occur.

From the publication EP 0 004 487 A1 a transmission is known in which the frictional connection either via a continuously variable Umschlingungsvariator runs or on a Ge gear stage constant translation, which is arranged parallel to the variator and whose translation corresponds to either the shortest or the longest translation of the variator. As a result, an optional power transmission between the constant and the variable branch is possible. By selectively operating, the overall operating life of the variator can be reduced, thereby enabling reduced dimensions and reduced production costs for the variator. In addition, the average efficiency of the transmission should be improved.

From the publication US 6,447,422 B1 For example, a transmission with a wrap-around variator is known, which is interposed in two different driving ranges between the input shaft and the output shaft of the transmission. In addition, the transmission has several gears of constant gear ratio, which are within the range of the variable ratios formed in the speed steps. The gears constant translation should be used according to this document primarily for an acceleration of the vehicle, which fuel consumption should be reduced. Another document which has a transmission with two stepless driving ranges and gears of constant translation is the document US 5,074,830 ,

Out the document WO 91/05183 a transmission is known which via a stepless power path with a variator and a power path with direct connection between the transmission input and the transmission output features.

The publication EP 857 267 shows a further transmission in which in addition to a direct drive connection of the drive shaft to the output shaft, a stepless driving range with the interposition of a Graham variator is possible.

A gearbox according to the publication JP 62 255 654 A has a continuously variable transmission with a toroidal variator for a front-transverse drive, which has a variable driving range and a second driving range with constant gear ratio.

From the publication DE 199 11 297 A1 is known a continuously variable transmission in which the drive torque is transmitted via conical friction wheels. In addition, a constantly translated gear exists. According to the teaching of this document switching between the two possible power flows takes place without appreciable speed difference, the contact force of the two friction wheels is largely withdrawn against each other.

From the publication EP 0 942 199 B1 Another toroidal transmission is known, which has a variable driving range and a second driving range of constant translation.

Of the The present invention is based on the object, a method to propose, which in a transmission with at least one stepless driving range and at least one constant gear use and at for defined states a choice between the stepless driving range and the constant Transmission gear can be taken.

The The problem underlying the invention is solved by the features of the claim 1.

According to the invention is a method for operating a drive train for a motor vehicle with a transmission. The transmission has at least one stepless driving range. In this driving range, a variator, in particular a looping variator or a Toroidvariator, interposed in the power flow between rule transmission input shaft and transmission output shaft, so that the translation is continuously variable. Furthermore, the transmission has at least one constant gear. The gear may be a direct gear with the ratio 1, a non-rotatable drive connection without the interposition of gear stages or one or more successive gear stages. In the constant gear, the drive power is transmitted from the transmission input shaft to the transmission output shaft, bypassing the variator, ie without significant power transmission through it.

According to the invention is a Control device for controlling the transmission provided, which at least fed a parameter becomes. The parameter correlates with an operating variable of the drive train, an environmental parameter and / or a state variable of a Power actuator. Regarding the operating size of the powertrain it is an arbitrary operating variable, such as a Power, an active power or a power loss, an upcoming one Load or a moment, a speed, a speed change, an on or off state a clutch or a brake, a position of a transmission element, in particular Switching element, a filling state a clutch or brake, a temperature of a lubricant, a lubricating condition such as an oil level, an operating temperature of the Powertrain or the transmission, an operating size of the drive unit such as the position of a throttle, an injection parameter, a discharged engine torque, a boost pressure, a state of Combustion medium such as temperature or composition or a Operating parameters of a catalyst.

at the environment parameter is any parameter from the environment of the motor vehicle, for example a geodetic height, a Outside temperature, an air pressure, a roadway parameter such as a Route with regard to altitude, Straight-line and cornering descriptive parameters.

at the state quantity of a Power actuator such as an accelerator pedal is it preferably a generalized coordinate of the position of the power actuator or a single or multiple temporal Derivation of the same.

Of the The present invention is based on the finding that a Selection of the constant gear should not be arbitrary, but rather in accordance with one or more of the aforementioned parameters should take place. If the controller is supplied with the parameters, then it can be adapted individually to the respective situation a decision is made, whether changed from a stepless driving range to a constant gear shall be.

In order to the control means an automatic change of a stepless Driving range to a constant gear, two must Criteria met On the one hand, there must be one parameter or several parameters have certain constellation, so the automatic change parameter controlled. About that In addition, monitoring takes place the gear ratio whether they are in the stepless driving range between a lower threshold and an upper threshold. Only if this the case is, the automated change is performed. On This way can be avoided even if a parameter is found in a suitable constellation, a constant one Gear selected which is inappropriate, for example, too much of the current translation deviates in stepless driving range, so that unfavorable switching characteristics or unfavorable Drive torque curves while switching or the drive unit through the change in an unfavorable Speed range is working. By the method according to the invention is a particularly simple method that allows an adjustment the appropriate gear state to vehicle and environmental parameters allows.

To Another proposal of the invention is a (return) change from the constant gear to a stepless driving range proviso the control device. Such a (return) change takes place in accordance with the Criteria that are comparable to those for a change are relevant from the stepless driving range to the constant gear. According to this embodiment, the variability becomes the drive a suitable state of the transmission increases. For a (return) change to the stepless Driving range can in particular the same parameters are used, so that no additional Measurements or signal lines are necessary. Preferably, for the change to the constant gear stage and the (reverse) change to stepless driving range the same control or test routine be used.

According to one embodiment of the method, the transmission has two stepless driving ranges and two constant gears. In this case, the automatic change to a constant gear or to a stepless driving range can be made even more varied. For example, it is conceivable that a change of one or both stepless driving ranges to a first constant transmission gear is automatically carried out by the control device, if at certain parameter constellations there is a translation in the continuously variable driving range which lies within a first transmission ratio range, while, in particular for other parameters, a second constant transmission ratio is selected for the presence of the ratio of a continuously variable driving range in a second transmission range. This allows a better and more flexible adaptation to the conditions.

According to one Another embodiment of the method according to the invention is a first constant gear designed as a synchronous gear whose translation approximately the translation at the transition from the first driving range to the second driving range. in this connection In particular, the synchronous gear is multifunctional, since on the one hand the transition from the first to the second driving range and on the other hand during certain Drive phases, depending on from the parameters and the translation, can be used as a permanent transmission gear. Especially advantageous is this configuration, if for the Synchrongang switching elements are used, which in any case for Realization of the driving areas are necessary. In the simplest case be for the Synchrongang the for both driving areas responsible Switching elements engaged.

For another inventive method is a constant gear designed as a direct gear. The inventive method can thus be extended to the use of a direct gear, which for example, advantageous in terms of power losses, the transmission ratio, the load of the variator and / or the noise emission of the transmission is.

According to one Development of the invention is the size of a lower threshold, an upper threshold and / or the transmission ratio range of the at least one parameter dependent. This is an improved adaptation of the automated change to individual conditions possible. Preferably, the size of the lower threshold, the upper threshold, the transmission ratio range and / or the dependence from the at least one parameter load or power dependent. The load dependency considered here in particular a road gradient, a vehicle weight or a loading condition, a driving resistance. The performance dependency in particular, concerns the position or timing of the Position of the power actuator or actual performance data of the Drive unit.

alternative or additionally is the size of the lower one Threshold, the upper threshold, the transmission ratio range and / or dependence of the at least one parameter of a temperature of a transmission oil dependent. Such a thing Design is based on the knowledge that, for example in the stepless driving range the power loss in the transmission increases, what an increase the oil temperature leads. If a critical oil temperature is exceeded, Thus, according to the invention a constant Transmission gear, in particular the synchronous gear or the direct gear be inserted, reducing the losses in the transmission at comparable driving conditions can be reduced. This can easily prevent overheating of the oil resulting in a reduction of the lubrication performance and thus an impairment to the function of the gearbox can. Possibly. takes place after successful lowering of the temperature redraft in a stepless driving range.

alternative or additionally is according to a preferred embodiment of the method according to the invention the size of the lower one Threshold, the upper threshold, the transmission ratio range and / or the dependence on the at least one parameter of a determined or approximated Remaining service life of the transmission, of a service life or a operating frequency depends on parts of the toroidal transmission. For example, in case that is recognized that the service life of a part, which in the power flow for the stepless driving range is closer to an estimated life, the reinforced constant gear selected so that the abovementioned part does not take up any more or less stress becomes. This can increase the overall life of the powertrain. The remaining life can be determined or approximated by a measurement or estimate the mechanical loading of the gearbox or the part, a numerical recording the operating frequencies or similar.

alternative or additionally can continue the size of the bottom Threshold, the upper threshold, the transmission ratio range and / or the dependence of which at least one parameter depends on a determined driver type. Thus, there is an adaptation to whether the motor vehicle from a as sporty recognized or one as more comfort-oriented Driver is driven. For a determination of a driver type come all known methods for automated driver type recognition in transmissions, in particular Automatic transmissions, into consideration.

According to a further proposal of the invention is lowered after a change in the contact pressure in a hydraulic pressure device of the variator. As a result, the drag torque of the variator can be lowered to a minimum who the, whereby the efficiency (further) can be increased. For example, as a result of the thrust bearing on the intermediate scooter, a minimum contact pressure for the variator arises as a function of the rotational speed. If this minimum contact pressure is above the sum of a basic mechanical contact pressure, for example as a result of a disc spring, and a centrifugal oil force of a contact pressure device, a regulated or controlled pressure is additionally provided. The value of this pressure can be set either constant over all operating conditions by means of an automatic device or variably by means of a controller.

Corresponding a preferred embodiment of the method according to the invention the controller controls the change to a constant gear and the return change to a stepless driving range with a hysteresis. This means that the change and the return change at different parameters and / or different gear ratios carried out becomes. This can be done, for example, by limiting of the transmission ratio range are adjusted accordingly or the evaluation of the parameters in the control device. For example, there is a defined vehicle speed, falls below a direct gear is redesigned, by a defined amount lower than the associated defined Vehicle speed, beyond which the direct gear is inserted. This allows reliable in a simple way Pendulum circuits are prevented.

On especially simple way according to another embodiment of the invention pendulum circuits be avoided if, after a change from a stepless Driving range to a constant gear change from the constant gear to the stepless driving range only after a wait becomes. equally may be one of the vehicle covered Way to avoid swinging circuits are taken into account.

According to one Another embodiment of the method according to the invention is a change from a stepless driving range to a constant gear or a change from a constant gear to a stepless driving range first performed, if for a period of time dependency the at least one parameter is met and the gear ratio in the continuously variable driving range exceeds a lower threshold, falls below an upper threshold or within a transmission ratio range lies. This has the consequence that short-term changes of the parameter and / or the translation area, which do not correspond to a long-term condition of the motor vehicle, no consideration Find. In a corresponding embodiment, that of the control device supplied Signal of the parameter and / or the gear ratio of a filtering be subject or it may be an average over several parameter values or translation values be formed.

Preferably are for a change or a return change Characteristics specified. Such characteristics can be particularly simple Way in a control unit be dropped and alike according to the design of the characteristic particularly well to the conditions be adjusted. The characteristics can be parameter dependent. Here it is possible that in dependence of the parameter are predetermined several characteristics. Alternatively or additionally can the characteristics themselves are a function of at least one parameter be.

Corresponding In a further development of the method, an environmental parameter is determined a driver assistance system taken into account. This can be GPS data or a navigation system. This is a prediction of a bill of exchange or a reversal possible, For example, when the driver assistance system a Change or return change indexing the road predicts. The driver assistance system in this case preferably a height information or a slope signal or curve information. For example It is possible by this embodiment of the invention, even before reaching to enter the corresponding gear or driving range on an incline, so that sufficient pulling power is provided at the beginning of the slope is without the variator applied with a high torque becomes.

Farther can be provided according to the invention be that one for a change responsible clutch or brake prefilled becomes when the at least one parameter approaches an area which a change or a return change indexed and / or the gear ratio to the transmission ratio range approaches. Thus, according to the invention be exploited that in an actually occurring change or change back one partial filling the clutch or brake has already been made, making a special fast change brought about can be. The pre-filling preferably takes place so far that individual slats or friction linings straight not or more or less already abut each other.

Furthermore, it can be provided according to the invention that after a change to a constant gear, the translation of the variator is slowly changed automatically in the direction. As a result, the drag torque on the variator ver be reduced. This has the consequence that the required minimum contact pressure of the variator decreases and at the same time the speed-dependent losses at the variator output and in any nachge switched gear stages (overlay planetary set) can be reduced. Preferably, the minimum drag torque is not achieved in the maximum underdrive, but at slightly longer translations.

According to one Further development of the invention is in the clutches and brakes present overexpression minimized to realize the gear, d. H. in the clutches and brake applied hydraulic pressure is not constant or on the maximum to be transferred Performance or the maximum moment adapted, but rather to the current performance and / or Torque requirement, if necessary with the addition of an absolute or percentage Safety. This allows the system pressure in the transmission as possible be lowered far, whereby hydraulic losses are minimized. This has a higher one Transmission efficiency result. Furthermore, by minimizing the Überanpressung the release the clutch or brake simplified.

Corresponding a development of the invention is the overpressure in the clutches and brakes of operating and / or environmental conditions dependent. The aforementioned dependence takes into account changes the closing conditions clutches and brakes, operating and / or environmental conditions depend. Examples of this are different filling conditions the controls clutches and brakes, especially caused by temperature fluctuations, which the viscosity change a hydraulic medium, or changes the friction conditions of the clutches and brakes, in particular a dependence a coefficient of friction of the operating and / or environmental conditions.

According to one special proposal of the invention is a function as a parameter descriptive of parts of the motor vehicle or powertrain Characteristic used. in this connection the characteristic can be any Part of the motor vehicle, the powertrain or gear relate. For example, the characteristic correlates with a functionality of the variator, so in the case that it is detected that the Variator in its functionality impaired is, increased or complete the motor vehicle over the constant gear ratio are operated. Is the function of a switching element or a transmission element for One driving level affected, so preferably the other driving level and the constant gears are controlled. Likewise, for the case of a failure of one with the power flow over one reinforced or constant gear transmission gearbox connected Completely on the other constant gear and / or the stepless Driving areas used become. This can be a functionality of the motor vehicle be ensured even in the event of a failure of a part. if necessary This can be a limited Driving, for example, to the nearest workshop, be enabled.

According to one further thoughts of the present invention, in particular by means of the control device, detected drive states, in which a increased Torque requirement is present. These are preferably a starting situation as well as immediate performance requirements the power control signal, for example, for accelerations related with overtaking. For the aforementioned Drive states follows a torque or power transmission under power sharing, with part of the power or the Drive torque over the variator and the rest Part about a parallel power branch takes place. In the parallel power branch is a coupling interposed, which operated slipping is, in particular for the adjustment of the drive torque to be transmitted and for adjusting the speed ratios. To the transmission output shaft become the benefits or moments of the two aforementioned performance paths superimposed again. According to this embodiment of the invention, the maximum transferable Not by the circumstances limited on the variator, but in addition to the variator transmitted power potential can transmit drive torque and power in the parallel power branch become. this makes possible in particular, for high output torques of the transmission nevertheless a small and compact Variator provided as in the dimensioning of the variator short-term Torque peaks transmitted through the parallel power branch can be not considered Need to become.

advantageous Further developments will become apparent from the dependent claims, the description and the Drawings. Other features are the drawing, especially the shown geometries of the components, the relative dimensions several of the same sizes or different components, the relative arrangement of the components to take each other and their active compounds together. The combination of features different in different Figures illustrated embodiments and / or the aforementioned Features with features of the embodiments of said state the technique is also possible.

A preferred embodiment of the device according to the invention will be explained in more detail with reference to the drawing. In the drawing shows:

1 a wheel plan of a toroidal transmission for a motor vehicle in longitudinal section and

2 a schematic diagram with a control device for carrying out the method according to the invention,

3 an exemplary map for the achievement of a minimum power loss with a representation of the areas for a preferred selection of a direct gear as a function of the parameters load and stationary vehicle speed and

4 another exemplary map for the achievement of minimum consumption with a representation of the areas for a preferred selection of a direct gear as a function of the parameters load and stationary vehicle speed.

The according to 1 illustrated toroidal transmission is used in motor vehicles, especially with standard drive. In the power flow between a central input shaft 10 and a coaxial output shaft 11 is a toroidal continuously variable transmission 12 arranged, which is a planetary gear total gear 13 and a planetary gear reversing gear 22 has. Coaxial and motion resistant to the input shaft 10 is a central intermediate wave 14 provided, which with the one central drive pulley 15 of the designed according to the 2-chamber principle variator 67 and with a first transmission member of the summation gear 13 forming, two-tier planet carrier 16 immovable is connected. The planet carrier 16 is in addition to the other central drive pulley for enabling the coaxial power passage 15a of the variator 67 immovable connected. Coaxial with the input shaft 10 and concentric with the central intermediate shaft 14 is a concentric intermediate wave 17 arranged, which are the two central driven pulleys 18 . 18a of the variator 67 with a second transmission member of the summation gear 13 forming, inner central wheel 19 rotatably connects.

The summation gearbox 13 has a third gear member in the form of an outer central wheel 20 on, with an indirect or immediate drive connection 27 between the third gear member and the output shaft 11 can be produced by a first switching element in the form of a clutch K1 for a lower driving range with lower driving speeds.

The summation gearbox 13 has a fourth gear member in the form of an inner central wheel 21 on, with an indirect drive connection 39 between the fourth gear member and the output shaft 11 can be produced by a second switching element in the form of a clutch K2 in an upper driving range with higher driving speeds. The input shaft 10 is bypassing the variator 67 by activation of a third switching element in the form of a clutch K3 at a transmission ratio i = 1 (direct gear) with the output shaft 11 can be brought into drive connection.

The clutch K3 for the direct gear is on the one hand with the central intermediate shaft 14 directly connected and on the other hand with the output shaft 11 via a radial drive bar 27a directly connected. The drive connection 27 is about the reverse gear 22 coupled with the output shaft. The clutch K1 is the one (here Zentralrad 26a ) of two outer central wheels 26 and 26a of the reverse gear 22 rotatably connected. The other central wheel (here Zentralrad 26 ) is with the output shaft 11 rotatably connected. The central wheels 26 . 26a lie axially on both sides of a radial support web 23a of the planet carrier 23 , by which latter against a non-rotating housing part 31 the transmission housing is fixed non-rotatably. At the planet carrier 23 are planets 30 rotatably mounted, the two sprockets each with one of the outer central wheels 26 . 26a comb, which have the same number of teeth and therefore the ratio 1: 1 between the input shaft 10 and output shaft 11 inevitably ensure. The sprockets are rotatably connected to each other, so the planets 30 are designed as Stufenplanet.

The planet carrier 16 has double planets 44 and one with the central intermediate shaft 14 rotatably connected radial drive bar 49 on. The double planets 44 consist of one major and one minor planet 45 and 46 , which comb each other and in the following as the first planet 60 and another planet are designated. The main planets 45 have one on the toroidal transmission 12 opposite side of the drive ridge 49 lying first sprocket 47 and one on the toroidal gearbox 12 facing side of the drive ridge 49 lying second sprocket 48 on. The sprockets 47 . 48 are rotatably connected with each other, so that the main planet 45 is designed as a stepped planet. The minor planets 46 comb with the outer central wheel 20 , At the main planets 45 comb the first sprocket 47 with the inner central wheel 21 and the second sprocket 48 with the inner central wheel 19 ,

The sprockets 47 and 48 the main planet 45 have unequal numbers of teeth, where sprocket 47 has the larger number of teeth.

sprocket 47 is from a first plane th 60 formed and sprocket 48 from a second planet 61 , The planets 60 . 61 are rotationally fixed to each other connected to a stepped planet 62 ,

In a first level 63 combs the first planet 60 radially inward with the inner central wheel 21 and radially outboard with the minor planet 46 , In a second level 64 combs the second planet 61 radially inward with the inner central wheel 19 , The second level 64 is axial between the variator 67 and the second level 63 arranged. Between the levels 63 . 64 is a medium wearing level 65 arranged, which the planet carrier 16 and the drive ridge 49 (at least partially). Between variator 67 and second level 64 is a front carrying plane 66 Arranged while on the variator 99 opposite side of the plane 63 a rear carrying plane 67 is arranged.

• – DE 101 21 042 C1 ,
• – DE ... mit dem Aktenzeichen P804712/DE/1 der Anmelderin
• – DE 100 40 039 A1 ,
• – DE 100 39 779 A1 ,
• – DE 100 21 912 A1 ,
• – DE 101 54 928 A1 und
• – DE 102 18 356 A1 ,

der Anmelderin verwiesen, welche vollumfänglich zum Gegenstand der vorliegenden Anmeldung gemacht werden.With regard to further embodiments of the power flow, the switching elements and the wheel plan of the illustrated embodiment or alternative embodiments is exemplified in the document

• - DE 101 21 042 C1 .
• - DE ... by file number P804712 / DE / 1 by the applicant
• - DE 100 40 039 A1 .
• - DE 100 39 779 A1 .
• - DE 100 21 912 A1 .
• - DE 101 54 928 A1 and
• - DE 102 18 356 A1 .

the applicant, which are fully made the subject of the present application.

For different operating ranges of the illustrated toroidal transmission, there is a force flow between the input shaft 10 and output shaft 11 as follows:

Geared neutral function

By a geared-neutral function is at the starting process with engaged, first clutch K1 with disengaged state of the second clutch K2 and the third clutch K3, the respective speed of the output shaft 11 and the directly to the clutch K1 directly connected gear members initially equal to zero and the partial ratio in the variator 67 set to a predetermined value.

Lower driving range:

In the subsequent, lower driving range with lower speeds of the output shaft 11 the first clutch K1 remains engaged. The power flows during forward travel over the direct path of the central intermediate shaft 14 to the summation gearbox 13 is branched, wherein a part via the first clutch K1 to the output shaft 11 flows and the other part on the variator 67 to the intermediate shaft 14 or flows back to the planet carrier of the summation gear. Circulating power thus occurs in the transmission arrangement, the power in at least one of the paths is higher than the transmission input power.

Synchronous point:

Of the said lower driving range and an upper driving range are such designed that translation at the upper end of the lower travel range of the translation at the lower end corresponds to the upper driving range. For a change from the first Driving range to the second driving range, the clutch K1 is disengaged while the clutch K2 indented becomes. By the above interpretation of the translations of the two driving ranges is the speed difference at the second clutch in the synchronous point K2 about 0, so that a smooth drive change without complex synchronization and permanent slipping operation of the clutches of the first Clutch K1 on the second clutch K2 is possible. The same applies to the change from the second driving range to the first driving range.

Upper driving range:

In the upper driving range, in which the clutch K2 is interposed, the transmission input power is generally divided into two parallel paths, so that the power component in both paths (variator 67 on the one hand and central intermediate shaft 14 on the other hand) is smaller than the transmission input power. Circulating power does not occur in this case.

Direct response:

With the engagement of the third clutch K3 can be an immediate drive connection between the input shaft 10 and the output shaft 11 getting produced.

Synchronous response:

In synchronous gear, the clutches K1 and K2 are closed. The variator 67 does not transmit any appreciable power in synchronous gear. In the synchronous gear results in a power split, in which the input power via two transmission paths, which each include one of the clutches K1, K2, flows to the output. The first power path in this case runs from the drive bar 49 over the first planet 60 , the inner central wheel 21 , the clutch K2, the drive connection 39 , an inner central wheel 25a to the planet 30 ,

In the other gear path is a power transmission from the drive ridge 49 over the minor planet 46 and a first planet 60 which the sprocket 47 forms, the outer central wheel 20 , Clutch K1, drive connection 27 , outer central wheel 26a to the planet 30 in which the powers of the first gear path and the second gear path overlap.

2 shows the interaction of a drive train 70 , a control device 71 , from sensors 72 - 74 and a power actuator 75 , The powertrain 70 has a drive unit, in particular an internal combustion engine, and a continuously variable transmission, in particular a toroidal transmission according to 1 , The control device 71 controls or regulates the drive train via a signal connection 76 , At the control device 71 It may be a single, integral control device for a powertrain management, which controls both the drive unit and the transmission. Alternatively, separate or mutually communicating control devices for the drive unit, for the transmission and possibly other parts of the drive train 70 be provided.

As parameters in the sense of the present invention, the control device 71 via a signal connection 77 Operating variables of the drive train 70 be supplied. Furthermore, the control device 71 via the signal connection 77 transmitted the present gear ratio of the transmission. Alternatively, the current transmission ratio in the context of a regulation of the translation via the control device 71 Be known anyway.

The aforementioned operating variables of the drive train are any operating variables of the drive train, in particular rotational speeds of gear elements, switching states of switching elements such as clutches, synchronizers, brakes, temperatures of transmission elements, wear sizes of clutches, brakes, shift elements or transmission elements, temperatures of a lubricant or hydraulic fluid and / or sizes that reflect the operability of transmission elements. Via a signal connection 78 become the controller 71 Signals from the sensors 72 . 73 fed.

By means of the sensors 72 . 73 operating variables are recorded which are outside the drive train 70 in a motor vehicle 79 are relevant. In this case, for example, the loading state can be detected by a detection of a loading amount of the chassis. Furthermore, a braking state via a sensor 72 . 73 be detected and fed to the controller.

Via a signal connection 80 becomes the controller 71 the requirement of the power actuator 75 fed. This is the power requirement of the driver, which is specified in particular by an accelerator pedal. Via a signal connection 81 is the control device 71 in conjunction with at least one sensor 74 which detects at least one environmental parameter such as an air pressure or an outside temperature.

By means of the aforementioned variables, a corrected output power of the drive unit can be determined. Furthermore, via a sensor 74 or a suitable driver assistance system, the current slope of a road or a future slope of the road are determined.

The stepless transmission allows in particular four different drive states for forward driving, namely the first driving range, the second driving range, the synchronizing gear and the direct gear. In particular, with variation of the speed of the Drive unit is both with a stepless driving range as well as with the synchronous gear or the direct gear the same transmission output speed achievable, so that in defined speed ranges at given speed of the motor vehicle at least two different drive states are possible.

3 shows an exemplary embodiment of a map 80 which is in the control device 71 is stored. In the map 80 are different operating ranges of the toroidal gear as a function of parameters, here a slope p over the steady speed v, applied. Here, the illustrated speed range correlates with an upper speed range of the motor vehicle, for example a range of 20 to 100% of the maximum speed of the motor vehicle.

In the map 80 gives the hatched area 81 Parameter constellations of p and v, in which preferably a direct gear is to be controlled. In the other areas shown 82 Preferably, a control of the second driving range. Not shown are further sub-areas, which correlate with a preferred control of the synchronous gear or the first driving range. The areas 81 and 82 be through a threshold curve 83 separated. In the event that out of one area 81 during operation of the motor vehicle, a parameter change takes place in such a way that the threshold curve 83 is exceeded in the direction of the area 82 , so there is a change from the direct gear to the second driving range. The corresponding is possible in the opposite direction.

The threshold curve 83 is oriented substantially perpendicularly for relatively small slopes p, ie for small slopes p, the transition between the areas takes place 81 and 82 for the same speed 84 , This is approximately until reaching a "critical" slope 85 , For large gradients p occurs between a speed 86 and the maximum speed 88 the change or return change for about the same slope 87 , Between the through the points ( 84 ; 85 ) such as ( 86 ; 87 ) predetermined boundary points runs the threshold curve 83 curved and without kink or crack. In a first approximation, the course in this area is approximately quarter-circle-shaped, in particular with a slight flattening. Straight 89 indicates the maximum achievable vehicle speed as a function of the slope of the road.

Comparable areas 81 . 82 can be determined and taken into account for a power requirement or a power requirement by a power actuator 75 , in particular for a planar movement of the motor vehicle. Taking into account several possible parameters results in a substantially analogous manner, a multi-dimensional parameter field. Such parameter fields can be mapped as mathematical functions. Alternatively, the continuous parameter space can be approximated and stored via discretized parameter maps.

3 indicates an exemplary map, which is optimized with regard to the power loss occurring. In 4 a map is given for a different optimization target, in particular for optimization in terms of minimizing consumption:
The upper range, the transition range and the vertical range of the threshold curve 83b are essentially the same as in 3 shown threshold curve 83 , wherein a displacement or extension in the direction of at least one parameter is possible. While according to 3 for low speeds above the speed 84 always takes the control of a direct gear, extends according to 4 the area 81b only for speeds above a limit speed 90 up to the speed axis, leaving only above speeds 90 for small gradients the direct gear is selected. Below the speed 90 Preferably, a control of the second driving range is carried out, in which case, when one of them is exceeded, another threshold value curve is used 91 predetermined limit a direct gear is selected. The threshold curve 91 runs through the point (speed 90 ; 0) and increases linearly at an angle of 30 ° to 45 ° with a reduction of the velocity in a first approximation. With smooth transition to the following areas has the threshold curve 91 between speeds 92 and 93 over a plateau, which with approximately constant slope 94 correlated. Following this, the threshold curve drops with further reduction of the speed and a smooth, rounded course 91 to a minimum 95 for the speed 84b from. The course of the threshold curve 91 is particularly dependent on the primary map of the driving motor.

A selection of a suitable one of a plurality of possible drive states takes place by means of the control device 71 , Of course, the present invention is also limited to starting from the in the 1 illustrated embodiment transmissible transmissions, for example, those in which an overlap of the driving ranges is given, creating a further option is given and / or more than two constant gears or deviating designed constant gears are provided.

Claims (29)

Method for operating a drive train for a motor vehicle having a transmission with a) at least one stepless driving range, in which by means of a variator the ratio between a transmission input shaft ( 10 ) and a transmission output shaft ( 11 ) is continuously variable, and b) at least one constant gear, in which the drive power, bypassing the variator of the transmission input shaft ( 10 ) to the transmission output shaft ( 11 ) is transferable, characterized in that c) a control device ( 71 ) at least one parameter is supplied, which correlates with ca) an operating variable of the drive train, cb) an environmental parameter and / or cc) a state variable of a power actuator ( 75 ), d) the control device ( 71 ) causes a change from a continuously variable driving range to a constant transmission gear da) depending on the at least one parameter and db) when the gear ratio in the stepless driving range exceeds a lower threshold value and / or falls below an upper threshold value. Method according to claim 1, characterized in that the control device ( 71 ) a return change from a constant gear to a Stufenlo sen driving range causes a) depending on the at least one parameter and b) when the gear ratio in the continuously variable driving range exceeds an upper threshold and / or falls below a lower threshold. Method according to claim 1 or 2, characterized that the lower threshold and the upper threshold, a transmission ratio range form, which the translation the constant gear stage includes. Method according to one of claims 1 to 3, characterized that the transmission has two stepless driving ranges and two constant ones transmission gears having. Method according to claim 4, characterized in that that the variator is a toroidal variator. Method according to claim 4 or 5, characterized that a constant gear is designed as a synchronous gear, its translation approximately the translation at the transition from the first driving range to the second driving range. Method according to one of claims 4 to 6, characterized that a constant gear is designed as a direct gear. Method according to one of claims 1 to 7, characterized that the size of the bottom Threshold, the upper threshold and / or the transmission ratio range depends on the at least one parameter. Method according to claim 8, characterized in that that the size of the bottom Threshold, the upper threshold, the transmission ratio range and / or dependence of which at least one parameter is load- or power-dependent. Method according to claim 8, characterized in that that the size of the bottom Threshold, the upper threshold, the transmission ratio range and / or dependence of which at least one parameter is dependent on a temperature of a transmission oil. Method according to claim 8, characterized in that that the size of the bottom Threshold, the upper threshold, the transmission ratio range and / or dependence from the at least one parameter from a determined driver type dependent is. Method according to claim 8, characterized in that that the size of the bottom Threshold, the upper threshold, the transmission ratio range and / or dependence of the at least one parameter from a determined or approximated one Remaining service life of the transmission, of a service life or a operating frequency is dependent on parts of the toroidal transmission. Method according to one of the preceding claims, characterized in that before a change or return change the speeds of the Drivetrain can be adjusted so that the speed difference at the for the change or return change competent Switching element is at least reduced. Method according to one of the preceding claims, characterized characterized in that after a change to a constant gear the contact pressure in a hydraulic contact pressure device of the variator is lowered to a minimum. Method according to one of claims 2 to 14, characterized in that the control device ( 71 ) controls the change to a constant gear and the return change to a stepless driving range with a hysteresis. Method according to claim 15, characterized in that that after a change from a stepless driving range to a constant gear change back from the constant gear to the stepless driving range only after a waiting period becomes. Method according to one of the preceding claims, thereby marked that a change from a stepless driving range to a constant gear or a return change from a constant Transmission gear to a stepless driving range is carried out only when for one time a) dependence the at least one parameter is fulfilled and b) the gear ratio in the continuously variable driving range exceeds a lower threshold, falls below an upper threshold or within a transmission ratio range lies. Method according to one of the preceding claims, characterized in that for a change or reversal one or more parameter-dependent characteristics ( 80 ; 80b ) between which an interpolation takes place. Method according to one of the preceding claims, characterized characterized in that an environmental parameter from a driver assistance system considered becomes. Method according to one of the preceding claims, characterized characterized in that one for one Change competent Clutch (K1; K2; K3) or brake is prefilled when the at least one Parameter to a range indicating a change or reversal approaching and / or the gear ratio the transmission ratio range approaches. Method according to one of the preceding patent claims, characterized characterized in that after a change of a stepless driving range to a constant gear the clutch (K2) of the stepless Driving range remains closed. Method according to one of the preceding claims, characterized characterized in that after a change, the translation of the variator in Direction changed slowly becomes. Method according to one of the preceding claims, characterized characterized in that an overpressure in the clutches (K1; K2; K3) and brakes for the realization of the Transmission gear is minimized. Method according to claim 23, characterized that the overpressure in the clutches (K1; K2; K3) and brakes of operational and / or Environmental conditions dependent is. Method according to one of the preceding claims, thereby marked that as a parameter A load parameter, - a performance parameter, A drive torque, - a temperature a clutch, brake, a hydraulic fluid or a gear oil, - An activity frequency or duration of a clutch, a brake, a gear stage or of the variator, - one geodetic Height, - the mathematical Derivation of the geodesic height or the road gradient, - one Ambient air pressure, - one Ambient temperature and / or A vehicle load condition used becomes. Method according to one of the preceding claims, characterized characterized in that the functionality as a parameter descriptive of parts of the motor vehicle or the drive train Characteristic used becomes. Method for operating a drive train for a motor vehicle having a transmission with a) at least one stepless driving range, in which by means of a variator the ratio between a transmission input shaft ( 10 ) and a transmission output shaft ( 11 ) is continuously variable, and b) at least one constant gear, in which the drive power, bypassing the variator of the transmission input shaft ( 10 ) to the transmission shaft ( 11 ) is transferable, characterized in that drive states are detected, in which an increased torque requirement is present, and for such drive states, a power transmission via the variator and a parallel power branch takes place, wherein an intermediate in the parallel power branch clutch is operated slipping. Method according to claim 27, characterized that the slipping operated clutch a second clutch K2 is. Method according to claim 27, characterized that the slipping operated clutch a third clutch (K3) is.