DE102006062902B4 - Method for operating a transmission for a motor vehicle - Google Patents

Abstract

Method for operating a transmission (3) for a motor vehicle (1), which cooperates as a transmission (7) provided with shift sleeves (8) with a clutch having a double clutch (9), ie a plurality of clutches (10, 11), which dual clutch (9) comprises a first clutch (10) and a second clutch (11) connectable to a first transmission shaft and a second transmission shaft, the first clutch (10) being connected to a first hydraulic cylinder (21) and the second clutch (10 ) is actuated by a second hydraulic cylinder (22), wherein the first hydraulic cylinder (21) from a first clutch pressure regulator (19, 25, 34, 39, 43) and the second hydraulic cylinder (22) by a second clutch pressure regulator (20, 26, 35 , 40, 44) and the first clutch pressure regulator (19, 25, 34, 39, 43) and the second clutch pressure regulator (20, 26, 35, 40, 44) by a hydraulic feedback line with a supply line to the respective Hydraulikz 21, 22) for decompressing a reference pressure, characterized in that between the first clutch pressure regulator (19, 25, 34, 39, 43) and the first hydraulic cylinder (21) a first switching device (23) and between the second clutch pressure regulator ( 20, 26, 35, 40, 44) and the second hydraulic cylinder (22), a second switching device (24) are provided and that the first clutch pressure regulator (19, 25, 34, 39, 43) and the second clutch pressure regulator (20, 26, 35, 40, 44) are each designed in the manner of a slide valve having an electromagnet, a valve piston and a reference pressure surface, and the method of operation comprises the following steps: (1) in the de-energized state of the electromagnet of a slide valve, a passage of a pressure oil to the hydraulic cylinder (21 , 22) is locked and the supply line to the hydraulic cylinder (21, 22) is opened against a tank, such that pressure oil flows out of the hydraulic cylinder (21, 22); (2) when the electromagnet is energized, an opening is closed to the tank and the pressure oil is released to the clutch supply line; (3) a reference pressure in the supply line to the respective hydraulic cylinder (21, 22) is removed and fed to a corresponding effective area, forming a reference force which is a product of reference pressure times reference pressure surface, and the reference force of the slide valve against the force of the electromagnet acts; ...

Description

The invention relates to a method for operating a transmission for a motor vehicle, which cooperates as a provided with shift sleeves gearbox with a plurality of clutches, preferably a dual clutch having clutch device.

It is known a transmission of a motor vehicle DE 103 49 220 A1 , which is designed as a manual transmission and is switched by means of a double clutch. The manual transmission has a first partial transmission and a second partial transmission, whose input shafts cooperate with a first and a second clutch of the dual clutch, which dual clutch is connected to an internal combustion engine of the motor vehicle. Intermediate shafts of the gearbox act on an output shaft, which drive wheels of the motor vehicle with the interposition of a differential.

The DE 10 2004 001 278 A1 deals with a dual-clutch transmission for a motor vehicle having two input shafts, two clutches and a first and a second drive shaft. The first input shaft is connectable to the first clutch and the second input shaft is connectable to the second clutch. The input shafts and drive shafts comprise intermeshing gears and at least two gears form a speed step. In this case, at least one gear of a gear stage is designed as a one-and / or disengageable idler gear and the other gear, for example. As a fixed gear.

From the DE 100 20 187 A1 shows a hydraulic circuit for an automated dual clutch transmission of a motor vehicle, wherein the dual clutch transmission comprises a countershaft transmission with two parallel power transmission branches and two clutches. In the dual clutch transmission operates a high pressure circuit with an actuator for the countershaft transmission and / or the clutches and a low pressure circuit for lubrication and / or cooling of components of the dual clutch transmission. In addition, a Verstellpumpe for variably providing the high pressure for the high pressure circuit is provided.

From the DE 103 47 203 A1 Arrangements for the hydraulic control of the transmission are known, wherein the focus of consideration is the supply of the clutch and Getriebeaktuatorik with pressurized oil through a clutch device and the transmission commonly associated pump assembly, based on the pressure medium for the actuation of the clutch assembly and for the actuation of the Gear is available or can be supplied.

From the EP 1 710 477 A1 is a switching system of a gearbox with at least two actuators for engaging and disengaging gears known. The switching system includes a group selector valve that selects one of the two groups of actuators.

From the EP 1 449 708 A1 is a synchronized dual-clutch transmission for a vehicle and a hydraulic arrangement for actuating the first clutch of the dual clutch with a first hydraulic cylinder and the second clutch of the dual clutch with a second hydraulic cylinder known. The coils of the clutch actuator valves are current-controlled. A predetermined current of the electromagnet determines the pressure in the (associated) clutch line, wherein a hydraulic feedback takes place. How the pressure regulation takes place in the valve, is in the EP 1 449 708 A1 not discussed.

Therefore, it is necessary to search in further references in order to find out how a pressure regulation could take place.

The EP 1 076 278 B1 describes a pressure control valve in which a magnet armature is received in an enclosed by a sleeve and a pole piece armature space, wherein passes through the armature centrally arranged, stepped bore. An annular channel is assigned to a low pressure area. To adjust a pressure, only a displacement of a liquid column within a liquid path takes place.

The textbook "Electronic Transmission Control EGS", Bosch, 1st edition explains that it knows two principles of pressure control in analog valves, namely the pressure regulator in slide design with a two-edge regulator and a pressure regulator in flat seat design as a single edge regulator.

The DE 195 24 652 A1 provides a valve which is an electrically controllable proportional pressure control valve and is adjusted by a stepping motor, wherein a non-rotating nut with a Position sensor is connected to transform the axial position of the nut against rotation in an electrical output signal.

The US 6 021 996 A claims to be able to realize a pressure control of a pressure control valve with a slidable coil.

Other ways in which a pressure control should be feasible, can be GB 843 654 B , of the DE 198 57 177 A1 and the KR 10 2003 0 033 841 A remove.

The object of the invention is to provide an operating method for a transmission for a motor vehicle, which cooperates as a provided with shift sleeves gearbox having a plurality of clutches, preferably a dual clutch clutch device and which is characterized by using easy to be realized components by an excellent function.

According to the invention, this object is achieved inter alia by the features of patent claim 1. Further, the invention ausgestaltende features are included in the following claims.

The advantages achieved by the invention are to be seen in the fact that the first clutch pressure regulator and the second clutch pressure regulator, which are each designed in the manner of a solenoid valve having a solenoid, ensure safe operation for the gear change of the gearbox. These clutch pressure regulators in conjunction with the method of their control allow a good function of the dual clutch of the transmission. The hydraulic cylinders immediately downstream connected in the manner of switching valves switching devices have a relatively large cross section to the tank line, whereby a relatively rapid emptying of the supply line to the tank can be achieved; said emptying causes a rapid separation of the associated coupling. The two clutch pressure regulators, which influence the first clutch and the second clutch of the dual clutch with the interposition of the switching means, a pressure-holding valve is connected upstream, which ensures that the respective operating pressure is set in the supply lines to the clutch cylinders within a working operating pressure.

Advantageous in terms of feasibility and effectiveness in the manual transmission with multiple shift sleeves, which cooperates with the first partial transmission and a second partial transmission of the said shift gear influencing double clutch is that each partial transmission has control elements which are formed by shift actuators. In order to functionally operate the transmission or the manual transmission with the sliding sleeves in connection with these control elements, the method developed for this purpose is suitable.

In addition, the transmission, which is designed as a shift sleeves having shift gear and cooperating with a plurality of couplings preferably acting as a double clutch coupling device cooperates, both in terms of use of components and also performance standards. Inter alia, the control elements for moving the sliding sleeves and the clutch pressure regulators contribute to this.

In the drawings, embodiments of the invention are shown, which are explained in more detail below.

Show it:

1 : a motor vehicle from above with a gearbox that is equipped as a manual transmission with shift sleeves and cooperates with a double clutch;

2 : a first hydraulic circuit diagram for actuating hydraulic cylinders for clutches of the double clutch;

3 : a view accordingly 2 with a second hydraulic circuit diagram;

4 : a view accordingly 2 with a third hydraulic circuit diagram;

5 a fourth hydraulic circuit diagram for controls for moving sliding sleeves;

6 : a detail X the 5 as a construction representation and on a larger scale;

7 a fifth hydraulic circuit diagram for actuating hydraulic cylinders for clutches of the dual clutch and control elements for moving shift sleeves;

8th : a view accordingly 7 with a sixth hydraulic circuit diagram;

9 : a view accordingly 7 with a seventh hydraulic circuit diagram;

10 : a view accordingly 7 with an eighth hydraulic circuit diagram.

A motor vehicle 1 includes an internal combustion engine 2 that under mediation of a transmission 3 and a differential 4 bikes 5 and 6 drives. Between internal combustion engine 2 and gear 3 as a manual transmission 7 with shift sleeves 8th is formed, is a double clutch 9 intended. The double clutch 9 has a first clutch 10 and a second clutch 11 on, with the first clutch 10 with a first partial transmission 12 and the second clutch 11 with a second partial transmission 13 interacts. The first partial transmission 12 are associated with a first gear G1, a third gear G3, a fifth gear G5 and a seventh gear G7; the second partial transmission 13 a second gear G2, a fourth gear G4 and a sixth gear G6 and a reverse gear GR - 1 -. To operate the first clutch 10 and the second clutch 11 - Clutch actuation KB - serve a first hydraulic cylinder 14 and a second hydraulic cylinder 15 ,

• (1) im unbestromten Zustand des Elektromagneten des Schieberventils ist ein Durchgang des Drucköls zur Kupplung gesperrt und die Zuleitung zur Kupplung gegen den Tank geöffnet, dergestalt, dass Drucköl aus der Kupplung abfließt;
• (2) beim Bestromen des Elektromagneten wird die Öffnung zum Tank geschlossen und das Drucköl zur Kupplungszuleitung freigegeben;
• (3) die Referenzdruckfläche gegen die Kraft des Elektromagneten wirkt;
• (4) eine Referenzkraft ein Produkt aus Druck mal Wirkfläche ist;
• (5) ein Referenzdruck wird in der Zuleitung zum jeweiligen Kupplungszylinder abgenommen und der entsprechenden Wirkfläche zugeführt;
• (6) die Zuleitung zum Kupplungszylinder wird dann geschlossen, wenn die Referenzkraft im Gleichgewicht zur Magnetkraft steht;
• (7) beim Absenken des Drucks in der Zuleitung zum Kupplungszylinder sich das Schiebeventil solange öffnet bis das Gleichgewicht zwischen der Kraft des Elektromagneten und der Referenzkraft wieder hergestellt ist;
• (8) zum Absenken des Drucks in der Zuleitung zum Kupplungszylinder wird die Kraft des Elektromagneten reduziert, dergestalt, dass die Referenzkraft den Ventilkolben gegen die verminderte Kraft des Elektromagneten bewegt und die Zuleitung zum Kupplungszylinder in Richtung Tank öffnet;
• (9) der Druck in der Zuleitung solange absinkt bis sich die Kraft des Elektromagneten und die Referenzkraft im Gleichgewicht befinden.

The first hydraulic cylinder 14 is a first clutch pressure regulator 16 upstream; the second hydraulic cylinder 15 a second clutch pressure regulator 17 - 2 ; first hydraulic circuit diagram -. The first clutch pressure regulator 16 and the second clutch pressure regulator 17 are each formed in the manner of an electromagnet having a slide valve, wherein each slide valve has a reference pressure surface. Regarding the mode of action of the clutch pressure regulator 16 and 17 reference is made to the method of clutch actuation KB according to the control of the clutch pressure regulator:

• (1) in the energized state of the solenoid of the spool valve, a passage of the pressurized oil is blocked to the clutch and open the supply line for coupling against the tank, such that pressure oil flows out of the clutch;
• (2) when energizing the electromagnet, the opening is closed to the tank and released the pressure oil to the clutch supply line;
• (3) the reference pressure surface acts against the force of the electromagnet;
• (4) a reference force is a product of pressure times effective area;
• (5) a reference pressure is taken in the supply line to the respective clutch cylinder and fed to the corresponding effective area;
• (6) the supply line to the clutch cylinder is then closed when the reference force is in equilibrium with the magnetic force;
• (7) when lowering the pressure in the supply line to the clutch cylinder, the slide valve opens until the equilibrium between the force of the electromagnet and the reference force is restored;
• (8) to reduce the pressure in the supply line to the clutch cylinder, the force of the electromagnet is reduced, such that the reference force moves the valve piston against the reduced force of the electromagnet and opens the supply line to the clutch cylinder in the direction of the tank;
• (9) the pressure in the supply line decreases until the force of the electromagnet and the reference force are in equilibrium.

In 3 - Second hydraulic circuit diagram - is shown that between the first and second clutch pressure regulators 19 and 20 and first and second hydraulic pressure cylinders 21 and 22 the first clutch 10 and the second clutch 11 a first switching device 23 and a second switching device 24 are provided. Each switching device, eg 23 , is designed in the manner of a switching valve, with a defined rapid separation of the respective clutch 10 or 11 that by the hydraulic cylinders 21 and 22 be influenced, bewerkstelligbar.

For pressure oil influencing is before the first and second clutch pressure regulators 25 and 26 a control device 27 arranged - 4 , third hydraulic circuit diagram -. The control device 27 is designed as a pressure maintenance valve. The latter ensures that the working pressure in the supply line to the first hydraulic cylinder does not drop below a safe operating pressure.

• (1) der Weg des Ventilkobens proportional zur Stromstärke des Elektromagneten ist;
• (2) bei unbestromter Stellung des Ventilkobens oder bei maximal bestromter Stellung des Ventilkobens Ölübergangsstellen die größten Querschnitte aufweisen;
• (3) in einer Mittelstellung des Ventilkobens die Ölübergangsstellen gesperrt sind;
• (4) auf dem Weg des Ventilkolbens von einer Endstellung zur Mittelstellung sich der Strömungsquerschnitt linear zur Stromstärke des Elektromagneten bzw. auch annähernd proportional die Durchflussmenge des überströmenden Öls verringert.

Out 5 - fourth hydraulic circuit diagram - shows how the shift sleeves 8th of the gearbox 7 or of each partial transmission 12 or 13 by a first control element 28 and a second control element 29 be operated - switching operation SchB -, which are designed as Schaltaktuatoren and structurally form Gleichzugzylinder, means the effective piston surfaces are the same size for both directions of movement. With the controls 28 and 29 or switching actuators connected is a socket selector valve 30 , which is designed as a solenoid valve with two switching positions. The socket selector valve 30 or solenoid switching valve upstream of a gearshift valve 31 that the basic functions of an axial piston 32 having a three-position valve - 6 - owns. The gearshift valve 31 is operated via the oil supply P and the outlets A and B, which can also be referred to as control channels. In addition, the axial piston works 32 with a proportional solenoid 33 together. The function of the manual transmission 7 in conjunction with the controls 28 . 29 , the socket selector valve 30 and the gearshift valve 31 is clarified by the method for controlling the transmission, according to which

• (1) the travel of the valve lifter is proportional to the current of the solenoid;
• (2) in the de-energized position of the valve head or at the maximum energized position of the valve head, oil-transfer points have the largest cross-sections;
• (3) in a central position of the Ventilkobens the oil transfer points are locked;
• (4) on the way of the valve piston from an end position to the middle position, the flow cross-section decreases linearly to the current of the electromagnet or approximately proportionally reduces the flow rate of the overflowing oil.

The 7 - fifth hydraulic circuit diagram - gives the operation of hydraulic cylinders for the clutches 10 and 11 - KB and control elements for moving the shift sleeves 8th - SchB - again. This is the clutch pressure regulators 34 and 35 an pressure maintenance valve 36 upstream, which contributes to the fact that at the beginning of a clutch overlap, the pressure in the actuated clutch does not fall below a set value.

According to 8th - Sixth hydraulic circuit diagram - is the manual transmission 7 , which in principle is approximately built like the manual transmission 7 , with a main pressure regulator 37 and a pressure balance 38 Mistake. The main pressure regulator 37 ensures a dominant pressure maintenance for the basic function clutch operation. The pressure balance 38 is powered and switched by pressures in the hydraulic cylinders of the clutches 10 and 11 and gives the respective higher clutch pressure as action pressure to the main pressure regulator 37 further. The main pressure regulator 37 is between pressure regulators (clutch pressure regulators) 39 and 40 the partial transmission 12 and 13 or a pressure maintenance valve 41 and the pressure balance 38 arranged with hydraulic cylinders of the clutches 10 and 11 are connected.

The 9 - seventh hydraulic circuit diagram - shows a first volumetric flow limiter 42 for the couplings 10 and 11 that operates between pressure regulators (Clutch pressure regulators) 43 and 44 or a pressure maintenance valve 45 the partial transmission 12 and 13 or the couplings 10 and 11 and a main pressure regulator 50 is provided. A second volume flow limiter 47 for the shift sleeves 8th is via lines on the one hand with pressure regulators 48 and 49 and on the other hand with a main pressure regulator 50 connected.

Based on 10 is clarified that a pressure balance 51 in conjunction with a switching pressure regulator 52 ensures a demand-based switching pressure. In addition, by a residual pressure regulator 53 and a cooling valve 54 a functionally compliant cooling oil pressure is reached, before the residual oil is fed to a pump suction side. LIST OF REFERENCE NUMBERS 1 motor vehicle 34 . 35 1st and 2nd clutch pressure regulator 2 Internal combustion engine 36 Pressure maintenance valve 3 transmission 37 Main pressure regulator 4 differential 38 pressure compensator 5 . 6 bikes 39 . 40 1st and 2nd clutch pressure regulator 7 manual transmission 41 Pressure maintenance valve 8th shift sleeves 42 1. Flow limiter 9 Double coupling 43 . 44 1st and 2nd clutch pressure regulator 10 first clutch 45 Pressure maintenance valve 11 second clutch 47 2. Flow limiter 12 first partial transmission 48 . 49 pressure regulator 13 second partial transmission 50 Main pressure regulator 14 first hydraulic cylinder 51 pressure compensator 15 second hydraulic cylinder 52 Switching regulator 16 first clutch pressure regulator 53 Residual pressure regulator 17 second clutch pressure regulator 54 cooling valve 19 first clutch pressure regulator G1 first course 20 second clutch pressure regulator G2 second gear 21 first hydraulic cylinder G3 third gear 22 second hydraulic cylinder G4 fourth gear 23 first switching device G5 fifth gear 24 second switching device G6 sixth gear 25 first clutch pressure regulator G7 seventh gear 26 second clutch pressure regulator GR reverse gear 27 Control device (pressure maintenance valve) KB Clutch actuation (1st and 2nd hydraulic cylinder) 28 and 29 1st and 2nd control element (1st and 2nd shift actuator) SchB shift operation 30 Sleeve selector valve P Control channel (oil supply) 31 Gear shift valve A, B Control channels (outgoing) 32 Axial piston (valve piston) 33 Proportional solenoid

Claims (18)

Method for operating a transmission ( 3 ) for a motor vehicle ( 1 ), which as one with shift sleeves ( 8th ) provided manual transmission ( 7 ) with a double clutch ( 9 ), ie several couplings ( 10 . 11 ) cooperating coupling device, which double clutch ( 9 ) a first clutch ( 10 ) and a second clutch ( 11 ), which are connectable to a first gear shaft and a second gear shaft, wherein the first clutch ( 10 ) with a first hydraulic cylinder ( 21 ) and the second clutch ( 10 ) with a second hydraulic cylinder ( 22 ), wherein the first hydraulic cylinder ( 21 ) from a first clutch pressure regulator ( 19 . 25 . 34 . 39 . 43 ) and the second hydraulic cylinder ( 22 ) from a second clutch pressure regulator ( 20 . 26 . 35 . 40 . 44 ) and the first clutch pressure regulator ( 19 . 25 . 34 . 39 . 43 ) and the second clutch pressure regulator ( 20 . 26 . 35 . 40 . 44 ) by a hydraulic feedback line with a supply line to the respective hydraulic cylinder ( 21 . 22 ) communicate to decrease a reference pressure, characterized in that between the first clutch pressure regulator ( 19 . 25 . 34 . 39 . 43 ) and the first hydraulic cylinder ( 21 ) a first switching device ( 23 ) and between the second clutch pressure regulator ( 20 . 26 . 35 . 40 . 44 ) and the second hydraulic cylinder ( 22 ) a second switching device ( 24 ) are provided and that the first clutch pressure regulator ( 19 . 25 . 34 . 39 . 43 ) and the second clutch pressure regulator ( 20 . 26 . 35 . 40 . 44 ) are each implemented in the manner of a slide valve having an electromagnet, a valve piston and a reference pressure surface, and the method for operation comprises the following steps: (1) in the energized state of the electromagnet of a slide valve, a passage of a pressure oil to the hydraulic cylinder ( 21 . 22 ) and the supply line to the hydraulic cylinder ( 21 . 22 ) is opened against a tank, such that pressure oil from the hydraulic cylinder ( 21 . 22 ) flows away; (2) when the electromagnet is energized, an opening is closed to the tank and the pressure oil is released to the clutch supply line; (3) a reference pressure in the supply line to the respective hydraulic cylinder ( 21 . 22 ) is removed and fed to a corresponding effective area, wherein a reference force is formed, which is a product of reference pressure times reference pressure surface, and the reference force of the spool valve acts against the force of the electromagnet; (4) the supply line to the hydraulic cylinder ( 21 . 22 ) is closed when the reference force is in equilibrium with the magnetic force; (5) when lowering a pressure in the supply line to the hydraulic cylinder ( 21 . 22 ) the spool valve opens until a balance between a force of the electromagnet and the reference force is restored; (6) for lowering the pressure in the supply line to the hydraulic cylinder ( 21 . 22 ), the force of the electromagnet is reduced, such that the reference force moves the valve piston against the reduced force of the electromagnet and the supply line to the hydraulic cylinder ( 21 . 22 ) opens in the direction of the tank; (7) the pressure in the supply line decreases until the force of the electromagnet and the reference force are in equilibrium. A method according to claim 1, characterized in that the supply line to the hydraulic cylinder ( 21 and 22 ) of the coupling ( 10 . 11 ) by the between the clutch pressure regulators ( 19 and 20 ; 25 and 26 ; 34 and 35 ; 39 and 40 ; 43 and 44 ) and the hydraulic cylinders ( 21 and 22 ) of the first and the second clutch ( 10 and 11 ) arranged first switching device ( 23 ) and second switching device ( 24 ) is emptied. Method according to claim 2, characterized in that each switching device ( 23 . 24 ), which is designed in the manner of a switching valve, a defined rapid separation of the respective coupling ( 10 or 11 ) accomplished. Method according to one of the preceding claims 1 or 2 or 3, characterized in that a front of the clutch pressure regulators ( 25 and 26 ; 34 and 35 ; 39 and 40 ; 43 and 44 ) arranged control device ( 27 ) is actuated to the pressure oil influencing. Method according to claim 4, characterized in that the control device ( 27 ), which is controlled by a pressure maintenance valve ( 27 . 36 . 41 . 45 ), a respective functional pressure in the supply lines to the hydraulic cylinders ( 21 . 22 ) does not set under a reliable pressure. Method according to one of the preceding claims 1 or 2 or 3 or 4 or 5, characterized in that the double clutch ( 9 ) a first partial transmission ( 12 ) and a second partial transmission ( 13 ) of the gearbox ( 7 ), wherein each partial transmission ( 12 or 13 ) Control elements ( 28 and 29 ) for moving sliding sleeves ( 8th ) operated by shift actuators ( 28 and 29 ) are formed. Method according to claim 6, characterized in that the sliding sleeves ( 8th ) of each sub-transmission ( 12 . 13 ) by the shift actuators ( 28 . 29 ) are moved, which are designed as a synchronous cylinder with equal effective piston surfaces for two directions of movement. Method according to one of claims 6 or 7, characterized in that the switching actuators ( 28 . 29 ) via a socket selection valve ( 30 ) operate. Method according to claim 8, characterized in that the socket selection valve ( 30 ) is operated as a solenoid valve with two switching positions, so an electromagnetic switching valve. A method according to claim 9, characterized in that a the solenoid switching valve ( 30 ) upstream gearshift valve ( 31 ), which is a basic function of an axial piston ( 32 ) having three-position valve, is operated for gear shifting. A method according to claim 10, characterized in that the gearshift valve ( 31 ), whose axial piston ( 32 ) with a proportional electromagnet ( 33 ) is operated via control channels (oil supply P and outlets A and B), wherein the axial piston ( 32 ) with the proportional electromagnet ( 33 ) works together. Method according to claim 11, characterized in that 1 ) a path of the axial piston ( 32 ) proportional to the current of the electromagnet ( 33 ); (2) at a de-energized position of the axial piston ( 32 ) or at a maximum energized position of the axial piston ( 32 ) Oil passage points of control channels (A, P or B, P) have largest cross sections; (3) in a middle position of the axial piston ( 32 ) the oil transfer points of the control channels (A and B) are locked; (4) on the way of the axial piston ( 32 ) From a final position to the middle position, a flow cross-section decreases linearly to the current of the electromagnet or approximately proportional to a flow rate of an overflowing oil. Method according to claim 12, characterized in that a pressure maintenance valve ( 41 ) upstream main pressure regulator ( 37 . 50 ) Ensures a dominant pressure maintenance for a basic function clutch operation. Method according to claim 13, characterized in that the main pressure regulator ( 37 . 50 ) with a pressure balance ( 38 ), whereby the pressure compensator ( 38 ) of pressures in the hydraulic cylinders ( 21 . 22 ) of couplings ( 10 and 11 ) is fed and switched, and the respective higher pressure than action pressure to the main pressure regulator ( 37 . 50 ) passes on. Method according to one of the preceding claims 13 or 14, characterized in that volume flows of the pressure oil to the hydraulic cylinders ( 21 . 22 ) of couplings ( 10 and 11 ) by a between the clutch pressure regulators ( 43 and 44 ) of the partial transmission ( 12 and 13 ) and the main pressure regulator ( 50 ) arranged first volume flow limiters ( 42 ) for the hydraulic cylinders ( 21 . 22 ) of couplings ( 10 and 11 ) are contained. Method according to claim 15, characterized in that a main pressure regulator ( 50 ) downstream second volume flow limiter ( 47 ) for the shift sleeves ( 8th ) Flow rates of the pressure oil to the shift sleeves ( 8th ). Method according to claim 16, characterized in that a pressure compensator ( 51 ) in conjunction with a second volume flow limiter ( 47 ) upstream switching pressure regulator ( 52 ) ensures a demand-based switching pressure. A method according to claim 17, characterized in that the switching pressure regulator ( 52 ) with a residual pressure regulator ( 53 ) and a cooling valve ( 54 ), whereby the residual pressure regulator ( 53 ) and the cooling valve ( 54 ) a functionally conforming cooling oil pressure is achieved, before the residual oil is supplied to a pump suction side.

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