DE102017220003B3 - Method for determining the power and / or torque in the travel drive of a CVT transmission of a work machine - Google Patents

Abstract

A method is proposed for determining a power (P; P) flowing through a CVT transmission (3) of a work machine (1) in which a current variator differential pressure (Δp) of a variator (6) of the CVT transmission (3) is at least a pressure sensor (11) is measured. According to the invention, a differential pressure characteristic map (13, 14), which determines the functional relationship between variator differential pressure (Δp) and power (P; P) as a function of a transmission ratio (i) of the CVT, is empirically determined on a test bench on the real CVT transmission (3). Transmission (3) reproduces, determined and stored in an electronic control unit (10) of the CVT transmission (3). Furthermore, the current power (P; P) is determined by the electronic control unit (10) during ongoing driving operation of the work machine (P) on the basis of the current variator differential pressure (Δp) and the differential pressure characteristic map (13, 14). Furthermore, the invention relates to a CVF transmission with such a differential pressure Kennfled (13, 14).

Description

The present invention relates to a method for power and torque determination in the drive of a CVT transmission according to the closer defined in the preamble of claim 1 and a corresponding CVT type transmission for a work machine according to the closer defined in the preamble of claim 21.

Power split transmissions are preferably used in work machines, for example as a transmission for tractors or construction machinery. The hydrostatic-mechanical power split transmission have a hydrostatic power branch and a mechanical power branch, which are summed again via a summation gear.

The publication DE 10 2015 202 981 A1 discloses a hydrostatic-mechanical power split transmission and a continuously variable CVT transmission and a method for operating the hydrostatic-mechanical power split transmission with a variator whose high pressure is detected by a high pressure sensor and depending on the detected high pressure in the hydrostatic power branch one of the hydrostatic power branch transmitted power is determined.

A disadvantage of CVT transmissions known from the prior art is that the occurring power losses in the respective transmission can only be described with great difficulty in terms of calculation, and that calculation models must be confirmed in a gearbox-specific manner via test measurements. Further, with a modified gear design, a software adaptation of the computational model is required, i. the control software must be geared specifically

An object of the present invention is to avoid the disadvantages associated with the prior art and to provide a method and corresponding apparatus in which with limited effort and with sufficient accuracy, the required data, especially the traction power flowing through the transmission and the Gearbox output torque determined in the current operating state of the transmission and supplied for the gear or work machine control.

The problem underlying the invention is solved by the features of claim 1 and of claim 21. Further advantageous embodiments will become apparent from the dependent claims and the drawings.

A method is proposed for determining a power flowing through a CVT transmission of a work machine. A CVT transmission is a continuously variable power transmission. In the method, a current variator differential pressure of a variator of the CVT transmission is measured with at least one pressure sensor. In order to be able to determine the power flowing through the CVT transmission with the measured variator differential pressure, a differential pressure characteristic map is determined on a test bench on the real CVT transmission, which represents the functional relationship between variator differential pressure and power as a function of a transmission ratio of the CVT transmission. The differential pressure map is stored after its detection in an electronic control unit of the CVT transmission. In the current driving operation of the working machine, the power currently flowing through the CVT transmission is determined by the electronic control unit based on the current variator differential pressure and the stored differential pressure characteristic map. Advantageously, therefore, no memory-intensive and compute-intensive computing models are needed. Furthermore, the method is independent of the structural design of the CVT transmission and can be applied to a variety of different gear versions standardized. Furthermore, no additional sensors are needed because only the sensory detectable Varitorkifferentialdruck is needed to determine the power flow. Furthermore, the effectivity influences of the variator and a downstream transmission on the output torque on the empirically measured transmission are recorded without detailed knowledge of actual sources of loss.

It is advantageous if a first reference pressure profile and / or a second reference pressure profile, in particular in a defined reference operating state of the CVT transmission, are detected empirically on the test bench for determining the differential pressure characteristic map. As a result, the test stand side effort for determining the differential pressure characteristic map can be reduced.

However, there is also the possibility that with curved maps the number of required reference pressure curves of the map curvature is adjusted. So it does not just have to be two reference curves with a low and high reference power. The determination and removal of one or more reference curves, for example at an average power, can be useful for increasing the process accuracy.

Furthermore, it is advantageous if a constant reference power is applied to the CVT transmission on the test bench for the empirical detection of the reference pressure curve, the gear ratios are passed through and the variator differential pressure is recorded.

In one embodiment of the invention, the first reference pressure profile for a constant first reference power and the second reference pressure curve for a comparatively higher, constant second reference power are detected. As a result, the test stand side effort for determining the differential pressure characteristic map can be reduced.

It is advantageous if, during the running driving operation of the working machine, a pressure working point in the differential pressure characteristic field is determined for the measured, current variator differential pressure and for a current gear ratio.

Furthermore, it is advantageous if the pressure working point is determined by interpolation between the at least two reference pressure profiles of the differential pressure characteristic map.

Furthermore, it is advantageous if, for the current gear ratio on the first reference pressure curve, a first pressure point and on the second reference pressure curve, a second pressure point are determined. Furthermore, it is advantageous in this regard if a pressure-interpolation curve is determined between these two by interpolation.

Thus, there is advantageously the possibility that the pressure working point is determined on the pressure-interpolation curve for the currently measured variator differential pressure and the current power, in particular mathematically, is derived from this from the differential pressure characteristic map.

In an advantageous further development of the invention, a first differential pressure characteristic map for a traction drive power flowing from a drive side to an output side of the CVT transmission is determined. Additionally or alternatively, it is advantageous if a current traction drive power is determined with the first differential pressure characteristic map.

It is also advantageous if a second differential pressure characteristic map is determined for a thrust output flowing from the output side to the drive side. Additionally or alternatively, it is advantageous if a current thrust output is determined with the second differential pressure characteristic map.

In order to determine a current output torque, it is advantageous if an output torque characteristic field is empirically determined on the test bench on the real CVT transmission which determines the functional relationship between an output torque (FIG. T _off ) and traction drive power ( P _on ) depending on the gear ratio ( i ) of the CVT transmission. Furthermore, it is advantageous if the output torque characteristic map is stored in the electronic control unit of the CVT transmission.

It is advantageous if the electronic control unit in the current driving operation of the working machine, a current output torque is determined based on the determined via the differential pressure map current traction drive power and the output torque map.

It is also advantageous if a first reference moment profile and / or a second reference moment profile, in particular in the defined reference operating state of the CVT transmission, are detected empirically on the test stand for determining the output torque characteristic map.

Furthermore, it is advantageous that a constant reference power is applied to the CVT transmission on the test bench for the empirical detection of the reference torque curve, the transmission ratios are traversed and in this case the output torque is recorded.

According to one embodiment of the invention, the first reference torque profile for a constant first reference power and the second reference torque curve for a comparatively higher, constant second reference power are detected.

There is the possibility that in the current driving operation of the working machine for the determined via the differential pressure characteristic map current traction drive power and for the current gear ratio, a torque operating point in the output torque map is determined. It is advantageous if the torque operating point is determined by interpolation between the two reference torque curves of the output torque characteristic map.

It is also advantageous if, for the current gear ratio on the first reference moment characteristic, a first moment support point and on the second reference moment profile a second moment support point are determined. Furthermore, it is advantageous if a torque interpolation curve is determined between these two by interpolation.

Furthermore, it is advantageous if the torque operating point is determined on the torque interpolation curve for the current traction drive power determined via the differential pressure characteristic map, and the current output torque is derived on the basis of this from the output torque characteristic map.

According to a fourth aspect of the invention, at least one of Reference operating state deviating actual operating state of the CVT transmission, in particular for a changed input speed and / or transmission temperature, determines a correction function for the respective reference pressure curve and / or reference moment curve and / or deposited.

It is advantageous if the reference pressure profiles and / or reference torque profiles are corrected during the ongoing driving operation of the work machine when changes occur on the basis of the correction functions.

Proposed is a CVT transmission for a work machine, in particular a land or construction machine, with a variator, at least one pressure sensor for measuring a current variator differential pressure and an electronic control unit. In the control unit, a differential pressure map and / or an output torque map is stored, which was determined empirically on a test bench on the real CVT transmission. The control unit is embodied such that a power currently flowing through the CVT transmission and / or a current output torque can be determined with the method described above, wherein the above-mentioned features can be present individually or in any desired combination.

• 1 eine schematische Darstellung einer Arbeitsmaschine mit einem CVT-Getriebe,
• 2 ein empirisch ermitteltes Differenzdruck-Kennfeld des CVT-Getriebes zur Ermittlung der aktuell durch das CVT-Getriebe fließenden Fahrantriebsleistung,
• 3 ein empirisch ermitteltes Abtriebsdrehmoment-Kennfeld zur Ermittlung eines aktuellen Abtriebsmoments der Arbeitsmaschine und
• 4 ein empirisch ermitteltes Differenzdruck-Kennfeld des CVT-Getriebes zur Ermittlung einer aktuell durch das CVT-Getriebe fließenden Schubleistung.

The invention is explained in more detail with reference to drawings. Show it:

• 1 a schematic representation of a work machine with a CVT transmission,
• 2 an empirically determined differential pressure characteristic diagram of the CVT transmission for determining the traction drive power currently flowing through the CVT transmission,
• 3 an empirically determined output torque map for determining a current output torque of the machine and
• 4 an empirically determined differential pressure characteristic map of the CVT transmission for determining a current through the CVT transmission thrust performance.

1 shows a schematic representation of a work machine 1 , At the work machine 1 For example, it is a land or construction machine. The working machine 1 has a drive unit 2 on. This is in particular an internal combustion engine. In a drive train of the working machine 1 is a CVT transmission 3 arranged ("CVT" in English means "continuously variable transmission"). The CVT transmission is thus a transmission in which the ratio is infinitely adjustable. In the present case, the CVT transmission 3 designed as a continuously variable power split transmission. It thus has a mechanical power branch 4 and a hydrostatic power branch 5 on.

In the hydrostatic power branch 5 is a variator 6 arranged. The variator 6 includes a drive-side pump and a discharge-side hydraulic motor. Furthermore, includes the CVT transmission 3 a summation gearbox 7 in which the on the mechanical power branch 4 and the hydrostatic power branch 5 divided services on the output side. In the present case is the summation gear 7 designed as a planetary gear, wherein a sun gear with the variator 6 , a planet carrier with the mechanical power branch 4 and a ring gear with an output shaft of the CVT transmission 3 connected is. The CVT transmission 3 is a manual transmission 8th downstream. From the manual transmission 8th the drive power is transferred to a drive axle 9 the working machine 1 directed.

Furthermore, the work machine includes 1 an electronic control unit 10 , With this, at least the CVT transmission 3 to be controlled. In addition, it is advantageous if via the electronic control unit 10 also the drive unit 2 and / or the manual transmission 8th can be controlled.

In the hydrostatic power branch 5 is furthermore at least one pressure sensor 11 arranged. With this pressure sensor 11 can be a variator differential pressure Ap be determined. Preferably, the variator comprises 6 a low-pressure side first pressure sensor and a high-pressure side second pressure sensor. Characteristic of such, in 1 illustrated machines 1 is it that over a power take-off 12 a part of the drive unit 2 generated drive power is dissipated to at least one auxiliary consumer, not shown here. In this case, the current is through the drive train to the drive axle 9 flowing traction power P _{An akt} unknown. As a result, the current output torque is also T _{ab akt} unknown. But not only in train operation, ie if part of the drive unit 2 generated power in the direction of the drive axle 9 flows, but also in overrun, that is, for example, when driving downhill a thrust performance P _thrust from the drive axle 9 in the direction of the drive unit 2 is the thrust that is currently flowing through the powertrain P _{thrust act} unknown. However, this information is necessary for the realization of powertrain functions.

To the necessary information, ie in particular the train driving the current traction power P _{An akt} and the current output torque T _{ab akt} and in overrun mode the current thrust output P _{thrust act} to be able to determine reliably, quickly and easily, are already in the CVT transmission 3 existing components, namely the pressure sensor 11 used. With the pressure sensor 11 can the variator differential pressure Ap or the current variator differential pressure Δp _act be determined.

To the through the CVT transmission 3 flowing services P _{on act} . P _{thrust act} as well as moments T _{ab akt} To be able to determine, are first empirically on a test bench on the real CVT transmission 3 maps 13 . 14 . 20 determined and in the electronic control unit 10 deposited. During ongoing driving receives the electronic control unit 10 according to 1 from the at least one pressure sensor 11 the current variator differential pressure Δp _act and can about this on the basis of maps 13 . 14 . 20 the desired sizes, ie in particular the current traction drive power P _{An akt} , the current output torque T _{ab akt} and the current thrust P _{thrust act} , be determined.

In 2 is a first differential pressure map 13 shown. This gives the functional connection between the via the pressure sensor 11 measurable variator differential pressure Ap and the traction drive power P _on depending on a gear ratio i of the CVT transmission 3 again.

To determine this first differential pressure characteristic map 13 is first for the real CVT transmission 3 on a test bench a first reference pressure curve 15 determined. For this purpose, first a constant first reference power P _{to ref (A)} on the CVT transmission 3 created. Subsequently, the gear ratios i passed through. During this, the at least one pressure sensor is activated 11 the variator differential pressure Ap recorded. At the end of this empirical method is now the first reference pressure curve 15 in front.

The same will now for at least a second reference power P _{to ref (B)} the traction drive power P _on carried out. As a result, becomes a second reference power P _{to ref (B)} the traction drive power P _on created and the gear ratios i passed through. Also in this case, the variator differential pressure is again Ap recorded, creating a second reference pressure curve 16 can be determined empirically. According to the present embodiment, the second reference pressure waveform 16 for one compared to the first reference pressure curve 15 higher constant second reference power P _{to ref (B)} the traction drive power P _on detected. Current traction power P _{on act} that is between the first reference power P _{to ref (A)} and the second reference power P _{to ref (B)} are - as explained in more detail below - during operation of the electronic control unit 10 determined via interpolation.

In the current driving operation of the working machine 1 based on the stored first differential pressure characteristic map 13 the current traction drive power P _{An akt} to be able to determine is first via the pressure sensor 11 the current variator differential pressure Δp _act measured. In addition to the current variator differential pressure Δp _act is also the current gear ratio i _act known. Based on these two parameters can now on the first differential pressure map 13 a first printing work point M in the first differential pressure characteristic map 13 be determined. This is done on the first reference pressure curve P _{to ref (A)} for the current gear ratio i _act a first pressure point 17 certainly. Furthermore, on the second reference pressure curve 16 a second pressure point 18 certainly. Between the first pressure point 17 and the second pressure point 18 becomes a pressure interpolation curve 19 certainly. Now, for the current, sensory measured Variator differential pressure Δp _act on the pressure-interpolation curve 19 the first printing work point M be determined. About this first printing work point M can now from the first differential pressure map 13 the current traction drive power P _{An akt} be derived.

In 3 is another in the controller 10 stored map displayed with the train in the current output torque T _{ab akt} can be determined. At the in 3 The map shown is an output torque map 20 , This represents the functional relationship between the output torque T _Ab and the traction drive power P _on depending on the gear ratio i of the CVT transmission 3 As explained in detail below, this is also on a test bench on the real CVT transmission 3 essentially analogously to the first differential pressure characteristic map 13 determined.

Accordingly, the test stand for determining the output torque map 20 first, a first reference moment characteristic 21 determined empirically. For this purpose, first a constant first reference power P _{to ref (A)} the traction drive power P _on on the CVT transmission 3 created. For the applied constant first reference power P _{to ref (A)} now the gear ratios i passed through. Here, the output torque T _Ab sensory recorded and recorded. The sensors for recording the output torque T _Ab are only available in the test bench environment. When installed, the CVT has a gearbox 3 about no such sensors, by means of which the output torque T _Ab can be measured.

After determining the first reference moment profile 21 becomes at least a second reference moment characteristic 22 determined empirically. This is the driving power P _on on a second reference power P _{to ref (B)} set and again the gear ratios i passed through. Furthermore, the output torque is also measured via the test stand-side sensor T _Ab recorded. The empirically recorded in this way output torque map 20 is in the electronic control unit 10 stored so that on this during operation of the working machine 1 can be accessed.

For determining the current output torque T _{ab akt} knows the electronic control unit 10 as the first parameter the current gear ratio i _act , Furthermore, the control unit knows 10 the current traction drive power P _contact , This became as above with respect to 2 explained, from the first differential pressure map 13 determined, in particular on the basis of the pressure sensor 11 sensory detected current variator differential pressure Δp _act , With the current gear ratio i _act and the current traction drive power P _{An akt} - The from the first differential pressure maps 13 is known - can now via interpolation the current output torque T _{ab akt} be determined.

For this purpose, first on the first Referenzmomentenverlauf 21 for the current gear ratio i _act a first moment support point 23 certainly. Furthermore, for the current gear ratio i _act on the second reference moment profile 22 a second moment support point 24 certainly. Between these two moment bases 23 . 24 can now via interpolation a moment-interpolation curve 25 be determined. About the current traction power P _{on act} can thus on these moments interpolation courses 25 a moment working point N be determined. About this moment working point N can now from the output torque map 20 the current output torque T _{ab akt} be read out.

In train operation - ie if at least part of the drive unit 2 generated power to the drive axle 9 is transferred - can thus over the in 2 illustrated first differential pressure map 13 on the basis of the pressure sensor 11 detected variator differential pressure Δp _act the current in the direction of the drive axle 9 flowing traction power P _{An akt} be determined. Furthermore, over the in 3 illustrated output torque map 20 about the now known current propulsion power P _{An akt} the current output torque T _{ab akt} be determined. The current output torque T _{ab akt} is thus indirectly, ie via the first differential pressure map 13 , with the current variator differential pressure Δp _act determined.

In overrun mode can with the in 4 shown second differential pressure map 14 the current thrust output P _{thrust act} be determined. The second differential pressure characteristic map 14 becomes empirically analogous to the first differential pressure map 13 determined. Accordingly, first, a first reference pressure curve 15 recorded. This will be a first reference power P _{thrust ref (A)} the thrust performance P _thrust set. Such thrust performance P _thrust occurs, for example, in a downhill driving the machine 1 on. As a result, this is the power flow P _thrust from the drive axle 9 in the direction of the drive unit 2 (see. 1 ). Once the first reference power P _{thrust ref (A)} is set, the gear ratios become i passed through. Here, the variator differential pressure becomes Ap recorded, so that the first reference pressure curve 15 is generated. The same applies to a higher second reference power P _{thrust ref (B)} the thrust performance P _thrust carried out. This results in the second reference pressure curve 16 , The empirically determined according to the above method on the test bench second differential pressure characteristic map 14 is in the electronic control unit 10 stored.

In the current driving operation of the working machine 1 can now from the electronic control unit 10 based on the second differential pressure map 14 the current from the drive axle 9 in the direction of the drive unit 2 flowing thrust P _{thrust act} be determined. This is done first for the current transmission ratio i _act the corresponding first pressure point 17 on the first reference pressure curve 15 determined. Subsequently, on the second reference pressure curve 16 the second pressure point 18 determined. About the two pressure base 17 . 18 can now via interpolation of the second pressure working point L be determined. This lies on the between the first and second pressure base 17 . 18 formed pressure-interpolation curve 19 , With knowledge about the position of the second pressure working point L can now the current thrust performance P _{thrust act} from the second pressure difference maps 14 be derived.

The maps described above, ie the in 2 illustrated first differential pressure map 13 , this in 3 shown output torque map 20 and / or the in 4 shown second differential pressure map 14 during their empirical determination on the test bench under defined reference operating states of the CVT transmission 3 determined. The reference operating states are, for example, a defined drive speed of the drive unit 2 and / or a transmission temperature of the CVT transmission 3 , In the current driving operation of the working machine 1 actual operating conditions are determined. If these deviate from the defined reference operating states, the reference curves, ie in particular the reference pressure profiles, will be different 15 . 16 the first and / or second differential pressure map 13 . 14 and / or the first and / or second reference moment profile 21 . 22 of the output torque map 20 , with one in the electronic control unit 10 stored correction function corrected.

The present invention is not limited to the illustrated and described embodiments. Variations within the scope of the claims are also possible as a combination of features, even if they are shown and described in different embodiments.

LIST OF REFERENCE NUMBERS

1

working machine

2

drive unit

3

CVT

4

mechanical power branch

5

hydrostatic power branch

6

variator

7

summing

8th

manual transmission

9

drive axle

10

control unit

11

pressure sensor

12

PTO

13

first differential pressure characteristic map

14

second differential pressure characteristic map

15

first reference pressure curve

16

second reference pressure curve

17

first pressure point

18

second pressure point

19

Pressure interpolation

20

Output torque characteristic map

21

first reference moment profile

22

second reference moment characteristic

23

first moment support point

24

second moment support point

25

Torque interpolation

Ap

Variatordifferenzdruck

Δp _act

current variator differential pressure

i

gear ratio

i _act

current gear ratio

P _{An akt}

current traction drive power

P _on

Travel drive performance

P _{to ref (A)}

first reference power of traction drive power

P _{to ref (B)}

second reference power of traction drive power

P _thrust

thrust

P _{thrust act}

current thrust performance

P _{thrust ref (A)}

first reference power of thrust output

P _{thrust ref (B)}

second reference power of thrust power

M

first pressure working point

L

second pressure working point

N

Torque operation point

T _Ab

output torque

T _{From nude}

current output torque

Claims (21)

Method for determining a power flowing through a CVT transmission (3) of a work machine (1) (P _{an act} ; P _{Schub akt} ), in which a current variator differential pressure (Δp _act ) of a variator (6) of the CVT transmission (3) with at least one pressure sensor (11) is measured, characterized in that empirically on a test bench on real CVT transmission ( 3) a differential pressure characteristic map (13, 14), which reproduces the functional relationship between variator differential pressure (Δp) and power (P _An ; P _thrust ) as a function of a transmission ratio (i) of the CVT transmission (3), and in one electronic control unit (10) of the CVT transmission (3) is stored and that of the electronic control unit (10) in the current driving operation of the working machine (1) the current power (P _{An akt} ; P _{thrust akt} ) based on the current variator differential pressure (Δp _act ) and the differential pressure map (13, 14) is determined. Method according to the preceding claim, characterized in that a first reference pressure curve (15) and / or a second reference pressure curve (16), in particular in a defined reference operating state of the CVT transmission (3 ), empirically recorded. Procedure after the previous one Claim 2 Characterized in that at the test stand for empirical acquisition of the reference pressure curve (15, 16) has a constant reference power (P _{An ref (A),} P _{at REF (B); ref} P _{shear (A),} P _{thrust ref (B))} on CVT transmission (3) is applied, the transmission ratios (i) are traversed and in this case the variator differential pressure (Δp) is recorded. Procedure after the previous one Claim 3 , Characterized in that the first reference pressure curve (15) for a constant first reference power (P _{An ref (A);} P _{thrust ref (A))} and the second reference pressure waveform (16) for a (higher, constant second reference power as compared to P _{At ref (B)} ; P _{push ref (B)} ) is detected. Procedure according to one of the previous Claims 1 to 4 , characterized in that in the current driving operation of the working machine (1) for the measured, current variator differential pressure (Δp _akt ) and for a current transmission ratio (i _akt ) a pressure working point (M; L) in the differential pressure characteristic map (13, 14) is determined , Procedure after the previous one Claim 5 , characterized in that the pressure working point (M; L) is determined by interpolation between the two reference pressure curves of the differential pressure characteristic map (13, 14). Procedure after the previous one Claim 6 , characterized in that for the current gear ratio (i _akt ) on the first reference pressure curve (15) a first pressure support (17) and on the second reference pressure curve (16) a second pressure support (18) are determined and that between these two by interpolation Pressure interpolation curve (19) is determined. Procedure after the previous one Claim 7 , characterized in that on the pressure-interpolation curve (19) for the current variator differential pressure (Δp _akt ) of the pressure working point (M; L) determined and based on this from the differential pressure characteristic map (13, 14), the current power (P _{to act} ; P _{thrust akt} ) is derived. Procedure according to one of the previous Claims 1 to 8th , characterized in that a first differential pressure characteristic map (13) for a from a drive side to an output side of the CVT transmission (3) flowing traction drive power (P _An ) and / or a second differential pressure map (14) for one of the output side to the drive side flowing thrust (P _thrust ) is determined and / or that with the first differential pressure map (13) a current traction power (P _{to act} ) and / or the second differential pressure map (14) a current thrust performance (P _{thrust act} ) is determined. Procedure after the previous one Claim 9 , characterized in that empirically on the test bench on the real CVT transmission (3) an output torque characteristic map (20), the functional relationship between an output torque (T _Ab ) and the traction drive power (P _An ) depending on the gear ratio (i) the CVT transmission (3) is reproduced, determined and stored in the electronic control unit (10) of the CVT transmission (3). Procedure after the previous one Claim 10 , characterized in that from the electronic control unit (10) in the current driving operation of the working machine (1) a current output torque (T _{Ab act} ) based on the first differential pressure characteristic map (13) determined current traction drive power (P _{to act} ) and the output torque Map (20) is determined. Procedure according to one of the previous Claims 10 to 11 , characterized in that on the test stand for determining the output torque characteristic map (20) a first Referenzmomentenverlauf (21) and / or a second Referenzmomentenverlauf (22), in particular in the defined reference operating condition of the CVT transmission (3), are detected empirically. Procedure after the previous one Claim 12 Characterized in that at the test stand for empirical acquisition of the reference torque profile (21, 22) has a constant reference power (P _{An ref (A),} P _{to ref (B))} is applied to the CVT (3), the gear ratios (i) are passed through and in this case the output torque (T _Ab ) is recorded. Procedure after the previous one Claim 13 , characterized in that the first reference moment characteristic (21) for a constant first reference power (P _{An ref (A)} ) and the second reference moment characteristic (22) for a comparatively higher, constant second reference power (P _{An ref (B)} ) becomes. Procedure according to one of the previous Claims 10 to 14 , characterized in that in the current driving operation of the working machine (1) for the first differential pressure characteristic map (13) certain current traction power (P _{to act} ) and for the current transmission ratio (i _akt ) a torque operating point (N) in the output torque map (20) is determined. Procedure after the previous one Claim 15 , characterized in that the moment working point (N) by interpolation between the two reference torque curves of the output torque map (20) is determined. Procedure after the previous one Claim 16 , characterized in that for the current gear ratio (i _akt ) on the first reference moment profile (21) a first moment support (23) and on the second reference moment characteristic (22) a second moment support (24) are determined and that between these two by interpolation Moments interpolation curve (25) is determined. Procedure after the previous one Claim 17 , characterized in that on the torque-interpolation curve for the determined via the first differential pressure map (13) current traction drive power (P _{to act} ), the moment working point (N) and based on this from the output torque map (20) the current output torque (T _{Ab akt} ) is derived. Procedure according to one of the previous Claims 2 to 18 , characterized in that for at least one of the reference operating state deviating actual operating state of the CVT transmission (3), in particular for a changed input speed and / or transmission temperature, a correction function for the respective reference pressure curve (15, 16) and / or Referenzmomentenverlauf (21, 22) is determined and / or deposited. Procedure after the previous one Claim 19 , characterized in that the reference pressure gradients and / or reference torque profiles in the current driving operation of the work machine (1) are corrected in the event of changes using the correction functions. CVT transmission (3) for a work machine (1), in particular a land or construction machine, with a variator (6), at least one pressure sensor (11) for measuring a current variator differential pressure (Δp _act ) and an electronic control unit (10), characterized in that in the control unit (10) a differential pressure map (13, 14) and / or an output torque map (20) is stored, which was determined empirically on a test bench on the real CVT transmission (3), and that the control device is designed such that a current through the CVT transmission (3) flowing power (P _{An akt} ; P _{thrust akt} ) and / or a current output torque (T _{Ab akt} ) with a method according to one or more of the preceding claims determined is.

Images