DE102014212182A1 - Method for controlling and regulating a drive train - Google Patents

Abstract

Method for controlling and / or regulating a drive train (1) for a motor vehicle with at least one pressure accumulator (27) each having a gas space (46) and a respective hydraulic fluid space (45) with the steps: introducing a hydraulic fluid into at least one pressure accumulator (27) in that a gas volume in the pressure accumulator (27) is reduced and the actual temperature and the actual pressure of the gas are increased and / or a hydraulic fluid is discharged from the at least one pressure accumulator (27), so that a gas volume in the pressure accumulator ( 27) is increased and the actual temperature and the actual pressure of the gas is reduced, detecting a measuring pressure of the gas in the at least one pressure accumulator (27) with at least one pressure sensor (47), determining an actual temperature of the gas, Calculating the actual volume of the gas with the determined actual temperature of the gas and the measuring pressure of the gas, calculating the energy which can be supplied to the pressure accumulator (27) by means of a reduction ng of the gas volume in the accumulator (27) from the actual volume to an end volume of the gas for a future charging of the pressure accumulator (27) and / or calculating the energy removable from the accumulator (27) by increasing the volume of gas in the accumulator Pressure accumulator (27) from the actual volume to a final volume of the gas for a future discharge of the accumulator (27), wherein the polytropic exponent of the pressure accumulator (27) is calculated with a P-model calculation and with the calculated polytropic exponent the energy storage (27) supplyable or removable energy is calculated.

Description

The present invention relates to a method for controlling and / or regulating a drive train according to the preamble of claim 1 and a drive train according to the preamble of claim 13.

State of the art

Motor vehicles with an internal combustion engine have a drive train for transmitting power from the internal combustion engine to at least one drive wheel. In this case, two drive wheels are generally driven by means of a differential gear on the motor vehicle. The internal combustion engine provides mechanical energy with a motor shaft, and by means of a power split transmission, this mechanical energy can be divided from the motor shaft to a first and second output shaft at the power split transmission. In this case, the first output shaft drives a mechanical drive sub-strand of the drive train, in which the mechanical energy is transmitted exclusively mechanically to the at least one drive wheel or the differential gear. The second drive shaft drives a hydraulic drive sub-strand and in the hydraulic drive sub-strand, a hydraulic transmission is integrated or installed, so that on the hydraulic drive sub-strand, the transmission of mechanical energy is also performed hydraulically. To operate the hydraulic transmission, a pump is required, which is driven by the second output shaft, and a hydraulic motor, which is driven by a hydraulic fluid from the pump. The hydraulic motor in turn drives the differential gear or the at least one drive wheel with a drive shaft on the hydraulic motor or a hydraulic gear drive shaft. Furthermore, the drive train to a pressure accumulator for pressure storage of hydraulic energy. With the driven by the second output shaft of the power split transmission pump, the hydraulic fluid can be supplied not only to the hydraulic motor, but also a pressure accumulator for storing hydraulic energy. This stored in the pressure accumulator hydraulic energy can be used later by passing the hydraulic fluid from the pressure accumulator to the hydraulic motor for driving the at least one drive wheel or the differential gear. In a recuperation operation, kinetic energy of the motor vehicle can be stored in the pressure accumulator as hydraulic energy.

The pressure accumulator is designed, for example, as a piston accumulator or a bladder accumulator. For the control and / or regulation of the drive train a knowledge of the current state of charge of the pressure accumulator is required. For this purpose, the pressure of the gas in the pressure accumulator and with a temperature sensor, the temperature of the gas can be detected with a pressure sensor and from this the volume of the gas can be calculated because the volume of the gas is a parameter for the state of charge of the pressure accumulator. When hydraulic fluid enters or leaves the pressure accumulator, the actual pressure and the actual temperature of the gas change as a function of time. The pressure sensor detects the actual pressure as a measuring pressure with a first time delay of approximately 0.01 s and the temperature sensor detects the measuring temperature as the actual temperature with a second time delay of approximately 2 to 3 s. The second time delay of the temperature sensor is thus substantially greater than the first time delay of the pressure sensor. To calculate the volume of the gas with the equation of thermal ideal gas at a known amount of substance and molar gas constant of the gas as accurate as possible knowledge of the pressure and the temperature at the same time is required to calculate the volume of the gas as accurately as possible. Due to the large second time delay of the temperature detected by the temperature sensor thus the volume of the gas can be calculated only with a low or insufficient accuracy, so that a sufficiently accurate determination of the state of charge with a rapid change in state of charge is possible.

The volume of the gas indicates the state of charge of the pressure accumulator. From a calculated actual volume of the gas and a future or desired end volume of the gas, the energy that can be supplied or removed from the pressure accumulator can be calculated. With a reduction of the actual volume of the gas to a smaller end volume of the gas energy is supplied to the pressure accumulator. Conversely, when the actual volume of the gas is increased to a larger end volume of the gas, energy is taken from the accumulator. When calculated using Poisson's equations and an assumed adiabatic state change from the actual volume to the final volume of the gas during the process time, the isentropic exponent of the gas, e.g. As air or nitrogen, used in the accumulator. In the assumed adiabatic change of state, a complete suppression of heat transfer from the gas or pressure accumulator into the environment and vice versa is assumed. However, this assumption does not correspond to the reality in the accumulator with an actual polytropic state change, so that the calculation of the energy which can be supplied to and removed from the pressure accumulator with the Poisson equation and an assumed adiabatic state change has a high degree of error or has a low accuracy.

The CH 405 934 shows a Schrägscheibenaxialkolbenpumpe whose non-rotating cylinder block for varying the delivery rate in dependence on the delivery pressure is longitudinally displaceable, wherein on the pressed by a spring in the direction of increasing the delivery cylinder block, a control slide unit is fixed with a spool.

The DE 27 33 870 C2 shows a control device for a Schrägenscheibenaxialkolbenpumpe, in which acts on both sides of the cradle for pivoting the swash plate depending on a hydraulically actuated swing wing on the engine, both motors are controllable by means of a pivot about the pivot axis of the cradle pivotally mounted plate-shaped control valve slide and adjusting the flow rate of the pump serve.

The DE 195 42 427 A1 shows a hydrostatic drive system for a hydrostatically operated vehicle.

Disclosure of the invention

Advantages of the invention

Method according to the invention for controlling and / or regulating a drive train for a motor vehicle having at least one pressure accumulator each having a gas space and a respective hydraulic fluid space, comprising the steps of: introducing a hydraulic fluid into at least one pressure accumulator so that a gas volume in the pressure accumulator is reduced and the actual Temperature and the actual pressure of the gas is increased and / or discharge of a hydraulic fluid from the at least one pressure accumulator, so that a gas volume in the pressure accumulator is increased and the actual temperature and the actual pressure of the gas is reduced, detecting a measuring Pressure of the gas in the at least one pressure accumulator with at least one pressure sensor, determining an actual temperature of the gas, calculating the actual volume of the gas with the determined actual temperature of the gas and the measuring pressure of the gas, calculating the energy that can be supplied to the pressure accumulator by a reduction of the gas volume in the Druckspei from the actual volume to an end volume of the gas for a future charging of the pressure accumulator and / or calculating the energy removable from the accumulator by increasing the volume of gas in the accumulator from the actual volume to an end volume of the gas for a future discharge operation of the pressure accumulator, wherein the polytropic exponent of the pressure accumulator is calculated with a P-model calculation and the computed polytropic exponent calculates the energy store that can be supplied or removed. Thus, a polytropic change of state is assumed for the charging process and / or the discharging process, so that the energy which can be supplied or removed from the pressure accumulator can be calculated more accurately than if an adiabatic change in state was assumed, ie. H. also heat transfer from the pressure accumulator into the environment and vice versa during the process time is taken into account.

In a further embodiment, the energy that can be supplied or removed from the accumulator is calculated with the calculated polytropic exponent, the measuring pressure of the gas, the actual volume of the gas and the final volume of the gas, in particular with an equation, preferably the Poisson equation,

In a supplementary embodiment, an end temperature of the gas associated with the final volume of the gas is determined with the P model calculation.

For the P model calculation, the polytropic exponent is expediently calculated with the measuring temperature, the end temperature, the actual volume and the end volume, in particular with an equation.

In an additional variant, in the P-model calculation, the process time of the future charging and / or discharging operation during the introduction or discharge of hydraulic fluid is determined from the actual volume to the final volume and / or in the P-model calculation, the ambient temperature, in particular detected by an ambient temperature sensor, in particular for the calculation of the end temperature and / or the P model calculation is carried out in each case for a charging or discharging the pressure accumulator and / or for several loading operations and / or unloading several P-model calculations are performed and / or the charging process and / or or unloading associated P-model calculation is performed before the start of the charging and / or discharging.

In a supplementary embodiment, in the P-model calculation, the process time is calculated from an assumed constant volume flow of hydraulic fluid introduction or discharge during the process time from the actual volume to the end volume of the gas and the amount of the difference of the actual volume and the End-volume of the gas determined.

In a further embodiment, in the P-model calculation, in particular for the calculation of the end temperature, the pressure accumulator, in particular the wall and / or the hydraulic fluid and / or a separating element, is subdivided into notional subelements and the P model computation with the notional ones Subelements carried out separately.

In a supplementary embodiment, the final gas temperature associated with the end volume of the gas is determined by the P model calculation by assuming the thermal conductivity and / or heat capacity of the pressure accumulator constant during the process time and the constant heat conductivity and / or heat capacity of the Accumulator is taken into account in the P-model calculation.

In an additional embodiment, the end temperature of the gas associated with the end volume of the gas is determined by the P model calculation by the heat conductivity and / or the heat capacity of the pressure accumulator during the process time depending on the process time and / or in dependence on the - Derived or volume of hydraulic fluid is determined and the variable thermal conductivity and / or heat capacity of the pressure accumulator is taken into account in the P-model calculation.

In a supplementary embodiment, the final volume is the actual maximum or minimum volume of the gas and / or the molar amount of gas in the pressure accumulator is kept constant during loading and unloading. The accumulator with the gas space with a constant amount of gas and the hydraulic fluid space with a variable amount of material or mass of hydraulic fluid has due to the design of an actual maximum and minimum (possible) volume of gas. The final volume may also be a value between the actual maximum and minimum volume of the gas or else the maximum or minimum volume. Suitably, the amount of substance and / or mass of the hydraulic fluid is changed in the pressure accumulator during loading and unloading.

In a further embodiment, the detection of the measuring pressure of the gas in the at least one pressure accumulator is carried out with the at least one pressure sensor with a first time delay to a variable depending on the time actual pressure of the gas and / or an initial temperature of Gas is determined and an ambient temperature is determined at the pressure accumulator and the temperature of the introduced and / or discharged hydraulic fluid in the pressure accumulator is determined and with the initial temperature of the gas, the ambient temperature at the pressure accumulator, the measuring pressure of the gas and the temperature a model calculation is performed on the hydraulic fluid introduced and / or discharged into the pressure accumulator, and the model calculation calculates a model temperature of the gas as the actual temperature of the gas. With the help of the model, the thermal properties of the pressure accumulator are detected, so that thereby the model temperature of the gas can be calculated. This makes it possible to calculate the model temperature substantially at the same time as the pressure of the gas detected by the pressure sensor, so that the volume of the gas can be calculated with high accuracy and thus also the charge state of the pressure accumulator, because the current actual Volume of the gas is the parameter for the current state of charge of the pressure accumulator.

In a supplementary variant, the drive train is controlled and / or regulated as a function of the calculated feedable and / or removable energy of the pressure accumulator, in particular the introduction of the hydraulic fluid into the at least one pressure accumulator and / or the discharge of the hydraulic fluid from the at least one pressure accumulator in dependence is controlled and / or regulated by the calculated supply and / or removable energy of the pressure accumulator.

In a supplementary variant, the initial temperature of the gas is determined by the fact that an initial temperature of the gas in the at least one pressure accumulator with at least one temperature sensor, in particular before startup and / or outside the operation of the pressure accumulator with a substantially constant temperature Gas is detected as a function of time, with a second time delay to an actual temperature of the gas, wherein the second time delay is greater than the first time delay and / or the time delay between the model Temperature and the actual temperature of the gas substantially equal to the first time delay. The initial temperature is preferably outside the operation of the pressure accumulator, for example, during the standstill of a motor vehicle, preferably constantly detected, so that with the startup, the initial temperature is available and due to the substantially constant temperature of the gas during the stoppage of the motor vehicle larger second time delay negligible.

In a further embodiment, the ambient temperature of the environment is determined by detecting the ambient temperature of the environment at the pressure accumulator with the at least one ambient temperature sensor and / or determining the temperature of the hydraulic fluid introduced and / or discharged into the pressure accumulator in that the temperature of the hydraulic fluid introduced and / or discharged into the pressure accumulator is detected with a hydraulic temperature sensor or calculated with an H model calculation and / or the volume of hydraulic fluid introduced and / or discharged into the accumulator with a hydraulic volume sensor is detected or calculated with an H-model calculation or is calculated from data of at least one hydraulic pump and / or at least one hydraulic motor for converting mechanical energy into hydraulic energy.

In a further embodiment, the pressure accumulator, in particular the wall and / or the hydraulic fluid and / or a separating element, is subdivided into fictitious subelements and the model calculation and / or P model computation is carried out separately with the fictitious subelements. The subdivision of the pressure accumulator, in particular individual components, eg. As a wall, a separating element, a hydraulic fluid space, the accumulator in sub-elements allows components with different part properties to map more accurately using the model and / or P-model.

In an additional embodiment, in the model calculation and / or P-model calculation, a wall of the pressure accumulator is subdivided into notional sub-wall elements, and the model calculation and / or the P-model calculation is performed separately on the sub-wall elements and / or in the model calculation and / or P-model calculation a hydraulic fluid space of the pressure accumulator is subdivided into fictitious subhydraulic elements with the hydraulic fluid and the model calculation and / or P model calculation is carried out separately on the subhydraulic elements and / or during the model calculation and / or P model computation a separation element between the hydraulic fluid space with hydraulic fluid and a gas space the gas is divided into fictitious Teiltrennelemente and the model calculation and / or P-model calculation is performed separately on the parting elements.

In the model calculation and / or P-model calculation, the substance quantity of the gas in the at least one pressure accumulator and / or the thermal conductivity of at least one subelement, preferably several subelements, of the at least one pressure accumulator and / or the heat accumulator capacity of at least one subelement, preferably several subelements, is expediently used. the at least one pressure accumulator and / or the volume and / or the mass of the hydraulic fluid introduced and / or discharged into the accumulator and / or the temperature of the hydraulic fluid introduced and / or discharged into the accumulator and / or the heat accumulator capacity of the accumulator introduced into the accumulator and / or discharged hydraulic fluid and / or the heat storage capacity of the gas and / or the surface of the wall of the at least one pressure accumulator and / or the first time delay and / or the second time delay considered. Thus, different parameters in the model calculation and / or P-model calculation are taken into account, so that an accurate calculation of the model temperature and / or the deliverable and / or removable energy is possible in an advantageous manner. Partial elements of the accumulator are factual and / or fictitious parts of the pressure accumulator, for example, the complete separation element, the entire gas in the gas space, the entire wall of the pressure accumulator or fictitious parts of the wall of the pressure accumulator, the entire hydraulic fluid or fictitious parts of the hydraulic fluid.

In a further embodiment, in the Model calculation and / or P-model calculation at least one equation, preferably a plurality of equations, placed on the heat conduction between the sub-elements and preferably the thermal conductivity between the sub-elements and / or the thermal conductivity of the sub-elements is taken into account and / or in the model calculation and / or P-model calculation at least one equation, preferably a plurality of equations, is set up for the heat gain of the gas due to the introduction of the hydraulic fluid and the caused compression of the gas and the heat loss of the gas due to the discharge of the hydraulic fluid and the caused expansion of the gas and / or in the model calculation and / or or P-model calculation, at least one equation, preferably a plurality of equations, is set up for the temperature change of the gas due to the change in the pressure of the gas detected by the pressure sensor and / or in the model calculation and / or P-model calculation. Model calculation at least one equation, preferably a plurality of equations, are set up for the heat loss and heat gain of the hydraulic fluid, in particular the subhydraulic elements, due to the in and out of the hydraulic fluid in and out of the hydraulic fluid space and / or at least one in the model calculation and / or P-model calculation Equation, preferably a plurality of equations, are placed on the heat conduction between the wall, in particular Teilwandungselementen, and the environment and preferably in the at least one equation, preferably the plurality of equations, the thermal conductivity and / or the heat storage capacity of the wall, in particular the Teilwandungselemente taken into account , The equations capture in the model and / or P-model different parameters of the accumulator for accurate calculation of the model temperature and / or the extractable and / or deliverable energy.

In a further refinement, a plurality of equations relating to a system of equations having at least one unknown parameter, in particular the temperatures of the subelements and / or the temperature and / or the volume of the hydraulic fluid introduced and discharged into the hydraulic fluid chamber, are combined and the system of equations is solved, so that as an unknown parameter the model temperature of the gas is calculated. Due to the multiplicity of equations, a system of equations for solving a multitude of unknown parameters can be set up.

In a supplementary variant, the actual volume of the gas is calculated from the model temperature calculated using the equation system or the specific actual temperature of the gas, the measured pressure of the gas detected by the pressure sensor, the molar mass of the gas and the molar gas constant of the gas calculated, in particular with the thermal equation of state of ideal gases.

In a further embodiment, the drive train is controlled and / or regulated in dependence on the determined actual volume of the gas, in particular the introduction of the hydraulic fluid into the at least one pressure accumulator and / or the discharge of the hydraulic fluid from the at least one pressure accumulator in dependence on the certain actual volume of the gas controlled and / or regulated.

In a further embodiment, the method for a piston accumulator and / or bladder accumulator is executed as the at least one accumulator and / or kinetic energy of the motor vehicle and / or drive energy of an internal combustion engine of a motor vehicle is converted into hydraulic energy by a hydraulic pump and in a recuperation Accumulator is stored by hydraulic fluid is introduced into the pressure accumulator with the hydraulic pump and a gas volume in the pressure accumulator is reduced and the actual temperature and the actual pressure of the gas is increased.

Preferably, in a hydraulic drive state, hydraulic energy is converted into mechanical energy by a hydraulic motor and the motor vehicle is driven by discharging hydraulic fluid from the pressure accumulator and leading it to the hydraulic motor and increasing a volume of gas in the accumulator and the actual Temperature and the actual pressure of the gas is reduced.

In an additional embodiment, the time delay between the model temperature and the actual temperature of the gas is less than 20, 10, 5, 2, or 0.2 times the first time delay.

Suitably, the model temperature of the gas is determined temporally after the determination of the initial temperature of the gas. In particular, with a measurement temperature of the gas, which is detected by the temperature sensor with a second time delay, carried out a plausibility check to the calculated model temperature.

Drive train according to the invention for a motor vehicle, comprising at least one hydraulic pump and at least one hydraulic motor for converting mechanical energy into hydraulic energy and vice versa, at least one pressure accumulator, wherein the method described in this patent application process is executable with the drive train.

In a further embodiment, a hydraulic pump and a hydraulic motor of a swash plate machine is formed, in particular, the drive train includes two swash plate machines, which are hydraulically connected to each other and act as a hydraulic transmission, and / or the Drive train comprises two pressure accumulator as high-pressure accumulator and low-pressure accumulator and / or the at least one pressure accumulator is designed as a piston accumulator and / or a bladder accumulator.

In a further embodiment, the at least one pressure accumulator each comprises a temperature sensor for detecting the initial temperature and / or the measuring temperature of the gas and a respective pressure sensor for detecting a measuring pressure of the gas and / or the drive train an ambient temperature sensor for detection the ambient temperature at the pressure accumulator comprises and / or the drive train comprises a hydraulic temperature sensor for detecting the temperature of the hydraulic fluid introduced and discharged into the pressure accumulator and / or the drive train comprises a computing unit with a computer and a data memory.

In a further embodiment, the drive train comprises a mechanical and hydraulic drive sub-train.

The invention further comprises a computer program with program code means which are stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is executed on a computer or a corresponding computing unit.

The invention also relates to a computer program product with program code means which are stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is executed on a computer or a corresponding computing unit.

In the following, an embodiment of the invention will be described in more detail with reference to the accompanying drawings. It shows:

1 a greatly simplified representation of a drive train,

2 a longitudinal section of a piston accumulator,

3 a side view of a bubble store and

4 a longitudinal section of the bladder memory according to 3 ,

Embodiments of the invention

An in 1 illustrated powertrain 1 is used for power transmission or for transmission of mechanical energy from an internal combustion engine 5 with reciprocating piston 6 to two drive wheels 32 a motor vehicle, not shown. The powertrain 1 is doing in a mechanical drive sub-string 2 divided and into a hydraulic drive sub-string 3 with a hydraulic transmission 22 in which mechanical energy is converted into hydraulic energy and vice versa.

A motor shaft 7 of the internal combustion engine 5 drives a drive shaft 10 a power split transmission 8th , z. B. a planetary gear 9 at. The planetary gear 9 drives with that of the motor shaft 7 on the power split transmission 9 transmitted mechanical energy a first output shaft 11 and a second output shaft 12 of the power split transmission 8th at. The first output shaft 11 of the power split transmission 8th drives the mechanical drive sub-string 2 with a mechanical transmission, not shown, and the second output shaft 12 of the power split transmission 8th drives the hydraulic drive sub-string 3 at. The mechanical drive sub-string 2 points next to the first output shaft 11 a first clutch 13 on which a transmission wave 34 connected is. This can be at a coupled first clutch 13 the mechanical energy from the first output shaft 11 on the transmission shaft 34 of the first mechanical drive sub-string 2 be transferred and from this to a mechanical coupling unit 30 , With a disengaged first clutch 13 is with a first fixing device 37 the first output shaft 11 held, so that the entire mechanical energy from the planetary gear 9 on the second output shaft 12 is transmitted. The mechanical coupling unit 30 carries the mechanical energy from the mechanical drive sub-string 2 , ie the transmission wave 34 and a hydraulic transmission input shaft 21 together. Here is the mechanical coupling unit 30 formed with gears, for example, to the effect that the transmission shaft 34 of the mechanical drive sub-string 2 and the hydraulic transmission input shaft 21 have the same speed ratio. From the mechanical coupling unit 30 becomes with the transmission wave 34 as a differential drive shaft 35 the mechanical energy on a differential gear 31 driven. The differential gear 31 drives through two wheel shafts 33 one drive wheel each 32 of the motor vehicle, not shown.

The hydraulic drive sub-string 3 is from the second output shaft 12 of the power split transmission 8th driven. It can be done in an analogous manner as in the mechanical drive sub-string 2 the power flow from the second output shaft 12 to a drive shaft 17 a first swash plate machine 15 with a second clutch 14 be solved and connected. At the released second clutch 14 is with a second fixing device 38 the second output shaft 12 held, so by the planetary gear 9 the entire mechanical energy to the first output shaft 11 is transmitted. The hydraulic transmission 22 has the first swashplate machine 15 and a second swash plate machine 18 on. The two swashplate machines 15 . 18 make a component 23 of the hydraulic transmission 22 dar. The first swash plate machine 15 can both as axial piston pump 16 as well as axial piston motor 36 operated and the second swash plate machine 18 both as axial piston pump 19 and as axial piston motor 20 , From the second swashplate machine 18 The hydraulic energy is converted into mechanical energy and thereby a drive shaft 21 or a hydraulic gear drive shaft 21 driven, which in turn this mechanical energy to the mechanical coupling unit 30 and thereby indirectly on the two drive wheels 32 transfers. The two swashplate machines 15 . 18 are with two hydraulic lines 24 hydraulically connected to each other. It is in each of the two hydraulic lines 24 as a 3-way valve 26 trained valve 25 existing, so that thereby the two swash plate machines 15 . 18 also hydraulically with two pressure accumulators 27 namely, a high-pressure accumulator 28 and a low pressure accumulator 29 , can be hydraulically connected.

The two swashplate machines 15 . 18 have a rotating cylinder drum (not shown) in which pistons are axially movable in piston bores. A swash plate or a swivel cradle of the two swash plate machines 15 . 18 is pivotable about a swivel angle and the larger the swivel angle, the larger the recoverable volume flow of the swash plate machines 15 . 18 at a same speed of the drive shaft 17 and the drive shaft 21 or hydraulic transmission drive shaft 21 , Will during operation of the hydraulic transmission 22 no hydraulic fluid in or out of a pressure accumulator 27 directed, have both Schwenkwiegen the two swash plate machines 15 . 18 the same tilt angle, since both swash plate machines 15 . 18 are formed identically, ie in particular have an equal number of piston bores with identical diameters in the cylinder drums and the drive shaft 17 and the hydraulic drive shaft 21 have the same speed. Different speeds of the drive shaft 17 and the hydraulic transmission input shaft 21 can with different swivel angles of the swivel weighing the first and second swash plate machine 15 . 18 be achieved.

During operation of the two swashplate machines 15 . 18 exclusively as a hydraulic transmission 22 is with the two hydraulic lines 24 hydraulic energy from the first swash plate machine 15 to the second swash plate machine 18 transferred and the greater the tilt angle of the two swash plate machines 15 . 18 is, the greater the volume flow of hydraulic fluid, which from the first to the second swash plate machine 15 . 18 flows and vice versa and the greater the torque on the drive shaft 17 and the hydraulic transmission input shaft 21 and vice versa. By changing the swivel angle of one or both swashplate machines 15 . 18 at a different tilt angle of the two swash plate machines 15 . 18 can the ratio between the speed of the drive shaft 17 and the hydraulic transmission input shaft 21 be changed and stepless, so that thereby a continuously variable hydraulic transmission 22 is available.

In a recuperation operation of the motor vehicle, the mechanical energy from the drive wheels 32 on the second swashplate machine 18 transferred and converted into hydraulic energy in this. It can by means of the two 3-way valves 26 Hydraulic fluid during the Rekuperationsbetriebes of the low-pressure accumulator 29 in the second swash plate machine 18 as axial piston pump 19 and from this under a higher pressure in the high-pressure accumulator 28 be initiated, ie the pressure in the high-pressure accumulator 28 be increased and thereby hydraulic energy in the high-pressure accumulator 28 get saved. For hydraulic drive of the motor vehicle, conversely, the hydraulic fluid under high pressure from the high-pressure accumulator 28 to the second swash plate machine 18 passed, which here as axial piston motor 20 acts and is converted into mechanical energy, thereby acting with the second swash plate machine 18 as axial piston motor 20 the hydraulic transmission input shaft 21 is mechanically driven. The hydraulic fluid is then from the second swash plate machine 18 to the low pressure accumulator 29 directed.

The two drive wheels 32 of the motor vehicle can either exclusively from the mechanical drive sub-string 2 be driven, provided the second clutch 14 is disengaged, or only from the hydraulic drive train 3 be driven, provided the first clutch 13 is disengaged, with the other clutch 13 . 14 Of course, it is engaged. In addition, the two drive wheels 32 at the same time both from the mechanical drive train 2 as well as from the hydraulic drive train 3 be driven, provided both clutches 13 . 14 are engaged. In this case, during this operation, the second swash plate machine 18 either exclusively from hydraulic fluid from the first swashplate machine 15 be driven, so that the second swash plate machine 18 exclusively with mechanical energy from the combustion engine 5 is driven. Optionally, additionally during this operation the second swashplate machine 18 also from hydraulic fluid from the high-pressure accumulator 28 be driven, so that thereby the second swash plate machine 18 both of mechanical energy from the internal combustion engine 5 as well as hydraulic energy from the high-pressure accumulator 28 is driven. In this latter drive case thus the two drive wheels 32 both with mechanical energy from the internal combustion engine 5 as well as with hydraulic energy from the high pressure accumulator 28 driven.

The two accumulators 27 as a high-pressure accumulator 28 and as a low-pressure accumulator 29 are for example as a piston accumulator 4 ( 2 ) or a bladder memory 51 ( 3 and 4 ) educated. The piston accumulator 4 has a wall 42 made of steel and the wall 42 also forms a cylinder for supporting a piston 43 as a separator 52 , The piston 43 separates one from the wall 42 enclosed total space in a hydraulic fluid chamber 45 , which is filled only with hydraulic fluid and in a gas space 46 , which only with gas, z. As air, is filled. Will be in the piston accumulator 4 through an inlet and outlet opening 49 Hydraulic fluid is introduced, the piston 43 moved by the non-compressible hydraulic fluid to the left, leaving the volume of the gas space 46 is reduced, that is, the actual temperature and the actual pressure of the gas is increased because the hydraulic fluid in a relatively short time through the inlet and outlet 49 is initiated, so that thereby the state of charge of the piston accumulator 4 is increased and this can be done vice versa. A pressure sensor 47 detects a measuring pressure of the gas in the gas space 46 and a temperature sensor 48 detects initial temperature and a measuring temperature of the gas in the gas space 46 , The pressure sensor 47 (shown in phantom) can also in the hydraulic fluid space 45 be arranged because the pressure of the gas in the gas space 46 is identical to the pressure of the hydraulic fluid in the hydraulic fluid space 45 , A filling valve 50 serves for filling and emptying the gas space 46 with gas. During filling, the substance quantity n of the gas is detected as well as the molar gas constant R of the gas. This is in the operation of the piston accumulator 4 the amount of substance n constant and thus both the amount of substance n and the molar gas constant R known.

In 3 and 4 is a bubble store 51 shown. In the following, essentially only the differences to the in 2 illustrated piston accumulator 4 described. The hydraulic fluid space 45 is through an elastic membrane 44 as a separator 52 made of plastic from the gas space 46 separated. By introducing hydraulic fluid through the inlet and outlet ports 49 into the hydraulic fluid space 45 is the volume of the membrane 44 enclosed gas space 46 reduced and vice versa. A hydraulic temperature sensor 53 detects the temperature of the hydraulic fluid in the room 45 Inlet and outlet hydraulic fluid, a hydraulic volume sensor 55 captures the volume of the hydraulic fluid in the space 45 Inlet and outlet hydraulic fluid and an ambient temperature sensor 53 detects the temperature of the environment env at the bladder accumulator 51 ,

The determination of the state of charge of the two accumulators 27 takes place by a determination of the volume of the gas with the help of the equation of thermal equation of ideal gases: pV = nRT (equation 1)

Where p is the pressure of the gas, V is the volume of the gas, n is the molar of the gas, R is the molar gas constant and T is the temperature of the gas. The substance quantity n of the gas and the molar gas constant R of the gas are fixed values which do not change during operation and are thus known, because these are determined before the model calculation. The calculation of the volume of the gas thus results from the above equation of thermal equation of ideal gases: V = nRT / p (equation 2)

It is thus a very accurate knowledge of the current temperature T and T _g and the pressure p of the gas in the gas space 46 required because the amount of substance n of the gas and the molar gas constant R are constant. The inlet and outlet of the hydraulic fluid takes place relatively quickly in the range of, for example, 5 to 50 s, preferably 10 to 20 s.

The pressure sensor 47 Measured as the measuring pressure, the actual pressure with a first time delay of approximately 0.01 s and the temperature sensor 48 Measures the measuring temperature and initial temperature as the actual temperature with a second time delay of about 2 to 3 s. The second time delay of the temperature sensor 48 is thus much larger than the first time delay of the pressure sensor 47 , To calculate the actual volume of the gas in the gas space 46 With the thermal equation of state of the gas at a known amount of substance n and molar gas constant R of the gas as accurate as possible knowledge of the pressure and the temperature at substantially the same current time is required to calculate the volume of the gas as accurately as possible. This is done with a model calculation of a computing unit 39 , z. B. an on-board computer of the motor vehicle, with a computer 40 or computer 40 and a data store 41 a model temperature is determined or calculated.

The change in the enthalpy ΔH of the gas in the gas space 46 when injecting or discharging hydraulic fluid from or into the hydraulic fluid space 45 results in: ΔH = dQ / dt + V · dp / dt (equation 3)

From this, the following differential equation for the change of the enthalpy ΔH of the gas is obtained with the equation of thermal equation of ideal gases:

Here, C _{p is} the specific molar heat capacity of the gas per molar mass, T _{g is} the temperature of the gas, Q is the heat losses of the gas into the environment, p is the pressure of the gas and n is the number of moles of the gas or the molar amount of the gas.

The temperature of the gas in the gas space 46 is dependent on the sub-elements which the gas space 46 Immediately limit. The sub-elements, which adjoin these sub-elements, influence the temperature of those sub-elements which the gas space 46 Immediately limit, so that it is necessary in a model calculation to calculate the temperature of all sub-elements, so that the model of the actual pressure accumulator 27 as accurately as possible. Factual components, e.g. B. the wall 42 , the pressure accumulator 27 can be divided into fictitious subelements. By increasing the number of fictitious subelements, the accuracy of the model can generally be increased, ie the model maps the reality with a higher accuracy.

The accumulator 27 is as a bubble store 51 formed with a membrane 44 as a separator 52 which the hydraulic fluid space 45 from the gas space 46 separates. The wall 42 of the accumulator 27 is subdivided into five notional sub-wall elements w1, w2, w3, w4 and w5. The hydraulic fluid space 45 is subdivided into two fictitious subhydraulic elements o1 and o2.

The temperature of the first partial wall element w1 is T _w1 , the temperature of the second partial wall element w2 is T _w2 , the temperature of the third partial wall element w3 is T _w3 , the temperature of the fourth partial wall element w4 is T _w4 and the temperature of the fifth partial wall element w5 is designated T _w5 . The temperature of the hydraulic fluid in the first subhydraulic element o1 is T _01, and the second subhydraulic element o2 is T ₀₂ . K denotes the thermal conductivity between two sub-elements. The subscript at K indicates these two subelements. Thus, for example, K _{o2w4 indicates} the thermal conductivity between the hydraulic fluid in the second partial hydraulic element o2 and the fourth partial wall element w4. The entire membrane 44 is denoted by the letter b and not subdivided into fictitious subelements. C is the specific heat capacity of a subelement and the subscript indicates the subelement. C ₀₂ is thus the heat capacity of the hydraulic fluid in the second Teilhydraulikelement o2.

By way of example for the second subhydraulic element o2, the following equation can be formulated with regard, in particular, to the heat conduction between the second subhydraulic element o2 and the other subelements which adjoin the second subhydraulic element o2 directly:

For all partial elements of the pressure accumulator 27 For example, the above equation may be specified analogously and these equations subsequently converted to a matrix form. In this case, the temperature change between the sub-elements is detected due to the thermal interaction with heat conduction among each other. This equation in matrix form is: T '= A * T (Eq. 6)

T 'is the vector or a matrix with a line for temperature change of the individual partial elements after the calculation step, A is the transfer matrix with the thermal conductivity and the specific heat capacity of the partial elements and T is the vector or a matrix with a column for the temperature of the individual Components or subelement before the calculation step. With this equation, the temperature change of the gas in the gas space becomes 46 due to the heat conduction to and from the gas detected.

In addition, the temperature of the gas is also influenced by the hydraulic fluid entering the hydraulic fluid space 45 is introduced and discharged, provided that the temperature of the incoming and outgoing hydraulic fluid from the temperature of the hydraulic fluid in the hydraulic fluid space differs from the temperature change due to a change in volume of the gas space 46 and the heat conduction between the wall 42 of the accumulator 27 and the environment env of the accumulator 27 , These factors are determined by the following equation with the matrix B, which additionally contains the matrix A for the thermal interaction between the subelements: T'= A * T + B * U (Eq. 7)

B is the input matrix with the above-mentioned factors for the subelements or the environment and U is the input vector or a matrix with a column for the temperature of the individual subelements or environment before the calculation step.

The volume change in the gas space 46 is determined with a model calculation or with a hydraulic volume sensor 55 detected and the volume change in the gas space is identical to that in the Hydaulikflüssigkeitsraum 45 incoming or outflowing volume of hydraulic fluid. The temperature of the hydraulic fluid space 45 incoming or outgoing hydraulic fluid is supplied with a hydraulic temperature sensor 53 recorded or calculated with an H model. The introduction of hydraulic fluid into the hydraulic fluid chamber 45 leads to an increase in the volume and a change in the temperature of the first and second subhydraulic element o1, o2, which is determined by the model calculation and vice versa during the discharge.

The input vector U takes into account the heat gain of the gas due to the introduction of hydraulic fluid and the compression of the gas caused thereby and the heat loss of the gas due to the discharge of hydraulic fluid and the expansion of the gas in the gas space caused thereby 46 , DQ gas_comp _indicates the positive heat gain of the gas due to compression and with a negative sign of dQ _{gas_comp there} is a loss of heat. For this purpose, the following equation can be established:

Equation 8 (equation 8) can be converted into the following form taking into account equation 4, and dT _{gas_comp} indicates the temperature change of the gas:

Equation 9 can be rewritten as Equation 10:

The pressure p of the gas is from the pressure sensor 47 and thus also the change dp / dt of the pressure of the gas per unit of time. Equation 10 corresponds to Equation 11 below and Equation 11, and dT _{gas_comp} / dt is written in a different form:

The input vector U also takes into account the heat loss and heat gain of the subhydraulic elements o1, o2 due to the introduction and discharge of hydraulic fluid into and out of the hydraulic fluid space 45 and the resulting mixing when introduced into the subhydraulic elements o1, o2. For this purpose, the following equation 12 can be set up for the inpuct vector U:

Here, T _{o is} the temperature of the first or second subhydraulic element o1, o2, T _in is the temperature of the hydraulic fluid conducted to the first or second subhydraulic elements o1, o2, ρ is the density of the hydraulic fluid, c _oil is the specific heat capacity of the hydraulic fluid and dQ _{oil_flow} / dt is the heat change due to the hydraulic fluid introduced per unit time and dV / dt is the volume change of the gas or hydraulic fluid per unit time.

The volume change is the volume change which has been calculated in the previous calculation step or iteration step. Due to the constant total volume of the pressure accumulator 27 The change in volume of the gas corresponds to the change in volume of the hydraulic fluid with a different sign, because an increase in the volume of the hydraulic fluid corresponds to an identical reduction in the volume of the gas, and vice versa.

Equation 12 can be rewritten into Equation 13 below:

Here, c _{oil is} the specific heat capacity of the hydraulic fluid, m _{oil is} the mass of the hydraulic fluid and dT _{oil_flow} / dt is the temperature difference of the introduced hydraulic fluid in the unit time.

Equation 13 can be transformed into the following Equation 14:

In the following equation 15, dT _{oil_flow} / dt is written from Equation 14 in another form:

The input vector U also takes into account the heat conduction between the partial wall elements w1, w2, w3, w4, w5 and the env environment at the partial wall elements w1, w2, w3, w4, w5. The environment env represents a fictitious infinite heat source in the model, and the heat conduction between partial wall elements w1, w2, w3, w4, w5 and the environment env is described by equation 16 below:

DT _{env_wall} / dt is the temperature change of the wall 42 or the partial wall elements w1, w2, w3, w4, w5 per unit time, T _env the temperature of the environment env, T _wall the temperature of the wall 42 or the partial wall elements w1, w2, w3, w4, w5, K _{wall_env} the thermal conductivity between the wall 42 or the partial wall elements w1, w2, w3, w4, w5 and the surroundings env and C _wall, the heat capacity of the wall 42 or the partial wall elements w1, w2, w3, w4, w5

Equation 16 can be rewritten into Equation 17 below:

The diagonal elements of the input matrix B with respect to the wall 42 or partial wall elements w1, w2, w3, w4, w5 is used with the following values.

werden als diagonale Elemente in die Transfermatrix A eingesetzt.The values

are inserted as diagonal elements in the transfer matrix A.

The elements of the transfer matrix A are adjusted with each calculating step and each iteration step, respectively, because the thermal conductivity and the heat capacity of the gas and the hydraulic fluid change with a change in the volume of the gas and the hydraulic fluid.

In the model calculation, the input matrix A is for all subelements:

Where K _{e1e2 denotes} thermal conductivity between the subelements e1 and e2, C _e1 denotes the heat capacity of the subelement e1, S / row denotes the sum of the relevant elements in the same row of the matrix, which are not diagonal.

The exemplary Equation 5 for the second subhydraulic element o2 may be rewritten into Equation 18 below:

Accordingly, for example, for row 4:

From equation 17, the second part of equation 17 is to be inserted in the diagonal elements of the transfer matrix A for the sub-wall elements w1, w2, w3, w4, w5.

That is S / row 9 for the corresponding exemplary partial wall element w5:

The temperature vector T is: T = [T _b T ₈ T _o1 T _o2 T _w1 T _w2 T _w3 T _w4 T _w5 ] ^T

The input matrix B is:

The input vector U is: U = [0 T 'T' _{gas_comp o1_flow} T _{'o2_flow} T _{env env} T T T _{env env env} T] ^T

In this case, in the input vector _{T'gas_comp} from equation 11, T'o1_flow _derives from equation 15 for the first subhydraulic element o1, _{T'o2_flow} from equation 15 for the second subhydraulic element o2 and T _env indicates the temperature of the env environment.

In each calculation step i, the transfer matrix A and the input matrix B and parts of the input vector U are calculated as a function of the charge state of the pressure accumulator 27 with the equations which are contained in the matrix and thus form a system of equations. T '= A * T + B * U

The temperature vector T'i of a subsequent calculation step _i can thus be calculated from the preceding calculation step with: T _'i = A · T _i-1 + B · U

The time span between the following and preceding calculation step i or iteration step i is Δt. T _'i is the temperature difference by the time .DELTA.t with the standard temperature unit (z. B. ° C or K) per unit time (z. B. sec or min). This results in: T _i = T _i-1 + T _'i .DELTA.t

At each calculation or iteration step, the gas temperature T _{gas can be taken} as the model temperature of the gas from the temperature vector T _i .

The volume of the gas or gas space 46 can thus be calculated with each calculation step i:

DV _g / dt is given as the volume change of the gas per unit time with:

The volume change V _{o of} the hydraulic fluid corresponds to the volume change V _{g of} the gas with opposite signs:

The calculation method can be used for any pressure accumulator 27 , for example, piston accumulator 4 , are used. For this purpose, only the sub-elements are adjusted accordingly. The number of sub-elements and the type in the pressure accumulator 27 divided into sub-elements are different here.

For effective and accurate control of the drive train 1 It is required that the currently in the accumulator 27 storable and removable energy for a future charging and discharging process with a process time t _{process of} the pressure accumulator 27 exactly known.

A general method for determining the storable and extractable energy is the assumption that an isentropic state change is present during the process time t _process , ie that an adiabatic system is present, so that no heat transfer between the gas space 46 and the env environment is present. The following two equations 21 and 22 are used:

E _discharge is the extractable energy up to the energy minimum volume V _{min of} the gas space 46 , E _charge the feedable or storable energy up to the energy with respect to the maximum volume V _{max of} the gas space 46 , V _curr is the current volume of the gas space 46 , p _curr is the current pressure in the gas space 46 and χ is the isentropic exponent or adiabatic exponent or the adiabatic constant. When unloading the pressure accumulator 27 becomes the volume of the gas frame 46 increases, so that in terms of energy minimum volume V _{min of} the gas space 46 the actual maximum volume V _{max of} the gas space 46 is. Conversely, when loading the pressure accumulator 27 the volume of the gas space 46 reduced, so that in terms of energy maximum volume V _{max of} the gas space 46 the actual minimum volume V _{min of} the gas space 46 is. The index at the volume V in equations 21 and 22 thus refers to the energy and not to the actual volume of the gas space 46 , When unloading hydraulic fluid from the accumulator 27 discharged and when loading hydraulic fluid in the accumulator 27 initiated.

The accumulator 27 has a heat transfer from and to the environment env. This has also been taken into account in the model calculation for model temperature determination described above. The calculation of E _discharge and E _charge assuming an adiabatic system thus has an error.

In the following, a P-model calculation is described for determining a polytropic exponent of the pressure accumulator 27 , For a special charging and discharging process of the pressure accumulator 27 the assumption can be made that the volume change is carried out with a constant volume flow, ie a constant volume change per unit time. The volume flow is dV / dt _estim . The elements of the input vector U are calculated, if relevant, for this volume flow. Using this information, ie the volume flow, the process time t _process can be calculated from the current volume V _curr to V _min or V _max or another volume V _end . V _end is a volume between V _min and V _max, or V _min or V _max itself.

The input matrix A is a function of the SOC, ie the current state of charge, and this was calculated in the model calculation to determine the model temperature of the gas. The end volume is from the arithmetic unit 39 specified. The current volume V _{curr of} the gas The beginning of the charging process or the discharging process is known from the model calculation. A volume is calculated as the amount of the difference between V _end (final volume) and V _curr (actual volume) and with the constant assumed volume flow the process time t _process can be calculated. For the P-model calculation, the input matrix A is used under the assumption that the input matrix A is constant during the end-loading process and the charging process. Thus, the input matrix for the current volume V _{curr of} the gas prior to the start of the charging process or the discharging process is _subsequently used as constant from the model calculation already carried out for the current state of charge. The assumption of a constant input matrix A represents a first possible solution of the P-model calculation and is described below in equations 23 to 31. From the equation 7 is already known: T'= A * T + B * U (Eq. 23)

Equation 23 corresponds to Equation 7 on the assumption that the input matrix A is constant during the final charge and the discharge.

Equation 23 can be rewritten as Equation 24: T (t) '= A * T (t) + B * U (t) (equation 24)

From Equation 24, Equation 25 can be determined: T (t) '-A * T (t) = B * U (t) (Equation 25)

Equation 24 can be multiplied by e ^At on both sides: e ^At (T (t) '- A * T (t)) = e ^At (B * U (t)) (Equation 26)

Equation 26 can be rewritten as Equation 27: d / dt (e ^At T (t)) = e ^At (B · U (t)) (Equation 27)

The integration of this equation 27 from 0 to t _process as the process time t _process , ie the duration of the charging or the discharging process, gives equation 28 or 29:

Assuming a constant volumetric flow, the vector T is constant and the equation simplifies to equation 30:

The result of the integration yields Equation 31, where I is an identity matrix with the dimension of the transfer matrix A:

Assuming a change in volume as a function of time due to the volume flow, the following equation 32 can be used to determine the temperature vector T at the end of the process:

From the temperature vector T, the temperature of the gas T _{end can be determined} at the end of the process. Thus, with Equation 32, T _{end is determined} as the end temperature of the gas at the end of the charging or discharging process. The process time t _process gives the duration of the discharge process or charging of the pressure accumulator 27 at.

In a second possible solution, the transfer matrix A is assumed to be variable during the change in volume with the process time t _process , and this results in the following already known equation 24: T (t) '= A * T (t) + B * U (t) (equation 24)

The solution to this with the variable transfer matrix A is given by Equation 33:

die Zustandsveränderungsmatrix (state transition matrix).It is

the state transition matrix.

The temperature T _{end of} the gas at the end of the process can be taken from the temperature vector T

With regard to further mathematical details, in particular to the above-described first and second proposed solutions for the P-model calculation, reference is made to the relevant mathematical literature, for example Schultz, DG, and Melsa J.L, State Functions and Linear Control Systems, McGraw-Hill, New York NY, 1967; Reid JG Linear System Fundamentals, McGraw-Hill, New York NY, 1983 ; Lueberger DG, Introdiction to Dynamic Systems, Theory, Models, and Applications, John Wiley and Sons Inc, New York NY, 1979 ; Dahleh, M., Dahleh, M. and Verghese, G., Lectures on Dynamic Systems and Control, Massachusetts Institute of Technology, Department of Engineering and Computer Science.

For a polytropic change of state or a polytropic system: TV ^n-1 = C

Where C is constant and n is the polytropic exponent.

oder

This results in:

or

The polytropic exponent n can thus be more accurately calculated with the first or second polytopic state change approach with the above Poisson equations 34 and 35 than assuming that there is an isentropic state change, ie, that an adiabatic system is present. The current actual temperature T _{curr of} the gas is determined by the model calculation, but can also be used with a temperature sensor 48 be detected, for example, if no previous major change in the volume of the gas space 46 was present, that is, the temperature of the gas has been substantially constant. The final temperature T _{end of} the gas is determined or calculated using the P model calculation. The actual volume V _{curr of} the gas is calculated using the model calculation or the variables derived therefrom, provided that the actual temperature T _{curr has been determined} with the model calculation. The end volume V _end is from the arithmetic unit 39 taking into account the requirements of the drive train 1 and the design of the pressure accumulator 27 certainly. For an isentropic state change with air as the gas in the gas space 46 χ as the adiabatic constant 1,4. In an isothermal state change, the polytropic exponent n = 1. Equation 35 above can thus be used for the pressure accumulator 27 For example, a polytropic exponent n between 1 and 1.4 can be calculated. The calculated polytropic exponent n can also be between 0 and 1.

E _discharge is the extractable energy up to the volume V _{end of} the gas space 46 and E _charge is the deliverable or storable energy up to the volume V _{end of} the gas space 46 , During a discharge process, the volume of the gas space 46 increased, ie V _end is greater than V _curr . During a charging process, the volume of the gas space 46 reduced, ie V _end is less than V _curr . Thus, for a polytropic state change taking into account heat transfer from the pressure accumulator 27 to the environment env, and vice versa, in more detail with the following Poisson equations for the pressure accumulator 27 with the polytropic exponent n the extractable and deliverable energy can be calculated:

Overall, with the inventive method for controlling and / or regulating the drive train 1 significant benefits. The of the arithmetic unit 39 Carried out model calculation makes it possible to determine the current model temperature T _{g of} the gas with a small time delay with respect to the actual temperature of the gas, so that the disadvantage of the large second time delay of the temperature sensor 48 is essentially canceled and thus the current volume of the gas as the actual volume and thus the state of charge of the pressure accumulator 27 can be determined with a high accuracy at the current time. In the P model calculation is for a future charging and / or discharging the accumulator 27 assumes a polytropic state change and calculates a polytropic exponent for a future charge or discharge. With the from the P-model calculation specific polytropic exponent can the pressure accumulator 27 energy that can be supplied in a charging process and the energy that can be removed in a discharging process can be determined more accurately. Depending on this, the powertrain 1 optimized and better controlled and regulated.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CH 405934 [0005]
• DE 2733870 C2 [0006]
• DE 19542427 A1 [0007]

Cited non-patent literature

• Schultz, DG, and Melsa J.L, State Functions and Linear Control Systems, McGraw-Hill, New York NY, 1967; Reid JG Linear System Fundamentals, McGraw-Hill, New York NY, 1983 [0124]
• Lueberger DG, Introdiction to Dynamic Systems, Theory, Models, and Applications, John Wiley and Sons Inc, New York NY, 1979 [0124]

Claims (15)

Method for controlling and / or regulating a drive train ( 1 ) for a motor vehicle with at least one pressure accumulator ( 4 . 27 . 51 ) each with a gas space ( 46 ) and one hydraulic fluid space each ( 45 ) comprising the steps of: - introducing a hydraulic fluid into the at least one pressure accumulator ( 4 . 27 . 51 ), so that a gas volume in the accumulator ( 4 . 27 . 51 ) is reduced and the actual temperature and the actual pressure of the gas is increased and / or - discharging a hydraulic fluid from the at least one pressure accumulator ( 4 . 27 . 51 ), so that a gas volume in the accumulator ( 4 . 27 . 51 ) is increased and the actual temperature and the actual pressure of the gas is reduced, - detecting a measuring pressure of the gas in the at least one pressure accumulator ( 4 . 27 . 51 ) with at least one pressure sensor ( 47 ), - determining an actual temperature of the gas, - calculating the actual volume of the gas with the determined actual temperature of the gas and the measuring pressure of the gas, - calculating the pressure accumulator ( 4 . 27 . 51 ) deliverable energy by reducing the volume of gas in the accumulator ( 4 . 27 . 51 ) from the actual volume up to a final volume of the gas for a future charging process of the pressure accumulator ( 4 . 27 . 51 ) and / or calculating the accumulator ( 4 . 27 . 51 ) removable energy by increasing the volume of gas in the accumulator ( 4 . 27 . 51 ) from the actual volume up to an end volume of the gas for a future discharge of the pressure accumulator ( 4 . 27 . 51 ), characterized in that with a P-model calculation of the polytropic exponent of the pressure accumulator ( 4 . 27 . 51 ) and with the calculated polytropic exponent the energy storage ( 4 . 27 . 51 ) energy that can be supplied or removed is calculated. Method according to claim 1, characterized in that the pressure accumulator ( 4 . 27 . 51 ) is calculated with the calculated Polytropenexponenten, the measured pressure of the gas, the actual volume of the gas and the final volume of the gas, in particular with an equation, preferably the Poisson equation. A method according to claim 1 or 2, characterized in that an end volume of the gas associated with the end temperature of the gas is determined with the P-model calculation. A method according to claim 3, characterized in that in the P-model calculation of the polytropic exponent is calculated with the measuring temperature, the end temperature, the actual volume and the end volume, in particular with an equation. Method according to one or more of the preceding claims, characterized in that in the P-model calculation, the process time of the future charging and / or discharging during the introduction or discharge of hydraulic fluid from the actual volume to the final volume is determined and / or in the P model calculation, the ambient temperature, in particular detected by an ambient temperature sensor ( 54 ), in particular for the calculation of the final temperature and / or the P-model calculation in each case for a charging process or discharging process of the pressure accumulator ( 4 . 27 . 51 ) and / or several P-model calculations are carried out for a plurality of loading operations and / or unloading operations and / or the P-model calculation associated with a loading operation and / or unloading operation is carried out before the start of the loading operation and / or unloading operation. Method according to one or more of the preceding claims, characterized in that in the P-model calculation, the process time from an assumed constant volume flow of introducing or discharging hydraulic fluid during the process time of the actual volume up to the End-volume of the gas and the amount of difference between the actual volume and the final volume of the gas is determined. Method according to one or more of the preceding claims, characterized in that in the P-model calculation, in particular for the calculation of the end temperature, the pressure accumulator ( 27 ), in particular the wall ( 42 ) and / or the hydraulic fluid and / or a separating element ( 52 ), is subdivided into notional subelements (w1, o1) and the P model computation with the notional subelements (w1, o1) is carried out separately. Method according to one or more of Claims 3 to 7, characterized in that the end temperature of the gas associated with the final volume of the gas is determined by the P model calculation by the heat conductivity and / or the heat capacity of the pressure accumulator ( 4 . 27 . 51 ) is assumed to be constant during the process time and the constant heat conductivity and / or heat capacity of the pressure accumulator ( 4 . 27 . 51 ) is taken into account in the P-model calculation. Method according to one or more of Claims 3 to 7, characterized in that the end temperature of the gas associated with the final volume of the gas is determined by the P model calculation by the heat conductivity and / or the heat capacity of the pressure accumulator ( 4 . 27 . 51 ) is determined during the process time as a function of the process time and / or as a function of the volume of hydraulic fluid introduced or discharged, and the variable heat conductivity and / or heat capacity of the pressure accumulator ( 4 . 27 . 51 ) is taken into account in the P-model calculation. Method according to one or more of the preceding claims, characterized in that the final volume is the actual maximum or minimum volume of the gas and / or the molar amount of the gas in the pressure accumulator ( 4 . 27 . 51 ) is kept constant during loading and unloading. Method according to one or more of the preceding claims, characterized in that the detection of the measuring pressure of the gas in the at least one pressure accumulator ( 4 . 27 . 51 ) with the at least one pressure sensor ( 47 ) is performed with a first time delay to a variable depending on the time actual pressure of the gas and / or an initial temperature of the gas is determined and an ambient temperature at the pressure accumulator ( 4 . 27 . 51 ) and the temperature of the pressure in the accumulator ( 4 . 27 . 51 ) introduced and / or discharged hydraulic fluid is determined and with the initial temperature of the gas, the ambient temperature at the pressure accumulator ( 4 . 27 . 51 ), the measuring pressure of the gas and the temperature of the pressure in the accumulator ( 4 . 27 . 51 ) introduced and / or discharged hydraulic fluid, a model calculation is performed and the model calculation a model temperature of the gas is calculated as the actual temperature of the gas. Method according to one or more of the preceding claims, characterized in that in dependence on the calculated feedable and / or removable energy of the pressure accumulator ( 4 . 27 . 51 ) the drive train ( 1 ) is controlled and / or regulated, in particular the introduction of the hydraulic fluid into the at least one pressure accumulator ( 4 . 27 . 51 ) and / or the discharge of the hydraulic fluid from the at least one pressure accumulator ( 4 . 27 . 51 ) in dependence on the calculated deliverable and / or removable energy of the pressure accumulator ( 4 . 27 . 51 ) is controlled and / or regulated. Powertrain ( 1 ) for a motor vehicle, comprising - at least one hydraulic pump ( 19 ) and at least one hydraulic motor ( 20 ) for the conversion of mechanical energy into hydraulic energy and vice versa, - at least one pressure accumulator ( 4 . 27 . 51 ), characterized in that a method according to one or more of the preceding claims is executable. Drive train according to claim 13, characterized in that a hydraulic pump ( 19 ) and a hydraulic motor ( 20 ) from a swashplate machine ( 15 . 18 ), in particular the drive train ( 1 ) two swashplate machines ( 15 . 18 ), which are hydraulically connected to each other and as a hydraulic transmission ( 22 ), and / or the powertrain ( 1 ) two accumulators ( 4 . 27 . 51 ) as a high-pressure accumulator ( 28 ) and low-pressure accumulator ( 29 ) and / or the at least one pressure accumulator ( 4 . 27 . 51 ) as a piston accumulator ( 4 ) and / or a bladder memory ( 51 ) is trained. Drive train according to claim 13 or 14, characterized in that the at least one pressure accumulator ( 4 . 27 . 51 ) one temperature sensor each ( 48 ) for detecting the initial temperature and / or the measuring temperature of the gas and a respective pressure sensor ( 47 ) for detecting a measuring pressure of the gas and / or the drive train 81 ) an ambient temperature sensor ( 54 ) for detecting the ambient temperature at the accumulator ( 27 ) and / or the drive train ( 1 ) a hydraulic temperature sensor ( 54 ) for detecting the pressure in the accumulator ( 27 ) comprises and / or the hydraulic drive fluid and / or the drive train ( 1 ) a computing unit ( 39 ) with a computer ( 40 ) and a data memory ( 41 ).

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