WO2013068175A1

WO2013068175A1 - Method for controlling shift processes of a transmission

Info

Publication number: WO2013068175A1
Application number: PCT/EP2012/069310
Authority: WO
Inventors: Florian Schneider; Anita WETZEL; Ingo Sauter
Original assignee: Zf Friedrichshafen Ag
Priority date: 2011-11-11
Filing date: 2012-10-01
Publication date: 2013-05-16
Also published as: DE102011086134A1

Abstract

A method for the noise-optimized engagement of gears in an automated shift transmission (6), having shift elements (30, 32) actuated by pressure medium, wherein, proceeding from a predefined system pressure in the shift device (24), the pressure level of the shift device (24) is, for an impending shift process, reduced to a value which, for said shift process, is just high enough to reliably perform the shift process.

Description

Method for controlling gear changes of a gearbox

The invention relates to a method for noise-optimized engagement of gears in an automated manual transmission according to the preamble of

Claim 1.

Automated manual transmissions for motor vehicles have been used for quite some time in different types of motor vehicles. They are usually called

Stage change gearbox designed in countershaft design, in which idler gears and fixed wheels are arranged on at least one transmission input shaft and a transmission output shaft and at least in pairs in meshing engagement with each other. To realize a specific transmission gear, a loose wheel is rotatably connected by means of a shift or sliding sleeve with a common transmission shaft, so that a torque transmission from the fixed to the idler gear. The sliding sleeve is rotatably and slidably disposed on the common transmission shaft and is operated differently from a manually switchable transmission by means of an actuator or an adjusting device, which in turn is controlled by a transmission control unit. Such an actuator can be known to be hydraulically, pneumatically or electrically actuated. In the fluid-operated operation, the movement of the sliding sleeves usually takes place via a switching cylinder with pistons. Since the switching process itself should run as fast as possible, it is mainly worked with large pressures. When operating the switching elements therefore arise especially when hitting the piston on the stop and the collision of

Gears Impact noises. In addition, the durability of the components is adversely affected by the hard impact.

The subject DE 10 2005 01 1 273 A1 of the Applicant also deals with this topic. Here it is attempted to work with a collision of two transmission parts with the lowest possible impact force, so that thus the lowest possible impact noise. For this purpose, the switching piston speed is varied so that the switching piston is moved during the switching path to a synchronization start of the transmission as possible with full pressure and high speed and after the end of the synchronization phase at low speed in his End position is brought. This is done via individually controllable pulsable valves that are mutually or mutually controllable. The following happens during the synchronization process:

- The inflow valve is opened and pressure medium reaches the working area. The piston starts its movement in working direction. The drain valve is included

closed.

- Upon the occurrence of a synchronization phase in the transmission of the switching piston remains shortly before its stop on the stop surface in a blocking position, wherein the pressurization of the switching piston increases considerably by further supply of pressure medium.

- The lying in the direction of movement of the switching piston part of the working space is relaxed throughout the switching process.

- With the end of the synchronization process, the control piston is unlocked, bringing it with great speed to its stop moves. In this case, the respective position of the piston is detected by a displacement measuring device and the

Information is processed in such a way that the venting of the part of the working space lying between the piston and the stop is stopped and an air cushion decelerates the impact.

- The pressure supply to the movement of the piston in the direction of movement is stopped after synchronization, which also has a positive effect on the Au freff force of the piston at the stop.

- Immediately before the stop, the pressure pad, which is in

Stop workspace has formed, vented, so as to make it possible to drive the piston to the final position. This is also controlled by distance measuring sensors.

As the noise level in modern vehicles continues to drop, noises that occur in the transmission during switching operations, more and more in the

Move fore. Especially in low-noise operating phases, for example, at a standstill, very slow driving or hybrid vehicles, when the engine is switched off or idle, fluid-actuated actuators are negative, since the moving masses are brought by the available pressure to high speeds and with this then open end stops or gear teeth. The object of this invention is therefore to develop a simple method for noise-optimized engagement of gears in an automated manual transmission, which can be implemented as possible without additional components to be installed.

To solve the problem, a method is proposed in which is lowered by a pressure reduction of the control pressure of the actuators of the system pressure for a given upcoming switching operation or a certain operating phase to a lower pressure level, so that the pressure is just high enough to the safe implementation to ensure the switching process. This pressure reduction ensures that the moving masses do not absorb so much kinetic kinetic energy and the force of the impact of the piston on an end stop or of gears on each other, is reduced. For this purpose, the possibility of controlling the pressure which serves to control the actuators must be given. However, the pressure reduction is not varied during the switching process itself.

In the gearbox different gear parts or assemblies

generates different levels of noise. So z. B. a circuit of a

Range set with planetary gearset produce a higher noise level than the circuit of a forward gear of the main transmission or a splitter group transmission. According to the invention, a pressure reduction can take place deliberately during the activation of particularly strongly noise-developing components or assemblies.

Depending on the operating phase different transmission components are adjusted. Thus, especially in operating phases, in which particularly strong noise-developing components or assemblies are switched, the pressure can be lowered. In the remaining phases of operation, the pressure is raised back to normal level of the system pressure.

The control pressure must not be lowered arbitrarily during the process of pressure reduction. It must always be considered that the functionality of the Circuit is preserved. With non-synchronized transmission parts, the control pressure must be sufficient to be able to adjust the switching elements safely. For synchronized transmission parts, the actuation pressure must be at least sufficient to perform the synchronization task safely and within an acceptable time.

In particular, in standstill circuits synchronized gear parts, however, a large pressure reduction pressure is allowed, since in these situations, the synchronization does not have to absorb energy, because the necessary to switch the new gear speed ratios already exist. This means, especially at or near vehicle standstill, in operating phases in which the circuits are most noticeable acoustically, the maximum permissible pressure reduction is highest. Therefore, during certain quiet operating phases, such. As standstill, slow driving or hybrid vehicles with deactivated combustion engine in which switching noise particularly striking, the driving pressure of the circuit to minimize noise are lowered.

The maximum driving pressure that can be lowered can be determined and determined experimentally. It can, for. B. by adaptation of a very low pressure level, the driving pressure of the circuits are raised so far, until no functional limitations occur. Likewise, it would be possible to start an adaptation from a high pressure level

perform. In this case, the driving pressure is lowered in circuits until functional limitations occur. These limit values must not be underrun and can be set as basic pressure values for the circuit in the operating phase tested in each case. Furthermore, it is conceivable that with respect to the

Noise level permissible pressure level to be determined by means of sensors. Modern automated manual transmissions are often equipped with inclination and acceleration sensors. If these sensors can measure accelerations of the actuators, it can be assumed that the striking of the actuators generates a jerk and this is measured by means of these acceleration sensors. Furthermore, it can be assumed that the strength of the resulting noise is proportional to the resulting jerk. Thus, z. B. be determined experimentally, how big ß the permissible jerk and thus the resulting noise may be. By means of the acceleration sensor, the corresponding circuits can be evaluated during operation and the drive pressure to be set for the upcoming circuits to be defined.

The invention will be described in more detail with reference to the following drawings: FIG. 1: Exemplary transmission construction

Fig. 2: Schematic diagram of a switching device according to the invention

The schematic representation in Fig. 1 shows an exemplary transmission structure of an automatic transmission 6 with a main gear 8 with the gears G1 to G5 and the reverse gear RG and a range group transmission 10 with a planetary gear set 12. The main transmission 8 is connected via a clutch 14 with the

Vehicle drive 16 connected. From the clutch 14, the transmission input shaft 18 is in the main gear 8 in. From there, the speed is transmitted depending on the gear selection via a countershaft 20 with the respective gear pairs and the associated translation back to the main shaft or transmission output shaft 22. The synchronization elements are identified by S1 to S4 and are used to adjust the speed of the idler gears in the main transmission 8 and in transmission modules such as the range group transmission 10. The synchronization control is performed in these automated transmissions by the pneumatic control of switching elements.

In Fig. 2, a switching device 24 is shown, the control of

Switching elements, a shift cylinder 30 for the main transmission 8 and a

Shift cylinder 32 for the range group transmission 10, shows. By the pressure supply 26 via the pressure line 28, the shift cylinders 30 and 32 are supplied to the circuit of gears with a system pressure. Shift cylinder 30 is a shift cylinder of the main transmission 8, the at least one synchronization S1 -S3 in

Main gear operated. An activation of further synchronizations is possible depending on the gearbox version. It is discussed here only on the actuators 30, 32 for switching or synchronizing the gears. Actuators for the dialing process are not shown. Further switching cylinder in the switching system, z. For example for synchronizations in other transmission modules are possible. In the following, five valves 34, 36, 38, 40 and 42 are shown. The valve 34 serves to adjust the drive pressure for the actuators 30, 32, which is received by the pressure sensor 44. The valves 36 and 38 are switching valves of the main transmission 8 and the valves 40 and 42 are switching valves of the range group transmission 10. The exhaust air is discharged via the exhaust air line 46. Both shift cylinders 30 and 32 are in the neutral position. All work spaces of the shift cylinders 30 and 32 are vented and the piston is centered in the shift cylinders 30 and 32nd

By way of example, the following four cases are described with reference to the presented switching system 24:

Case 1: Switching a not very noise-developing component in one

Standard operating phase

Case 2: Switching a strongly noise-developing component in one

Standard operating phase

Case 3: Operating phase with switching of at least one strongly noise-developing component

Case 4: Switching a non-noise developing component in one

quiet operating phase

Case 1: The piston of the shift cylinder 30 is to be retracted completely in a standard operating phase. This process has been identified as a switching operation with components that do not develop much noise. Valve 34 and valve 38 are therefore switched and the complete system pressure in the pressure line 28, for

Pressure connection of the valves 34, 38 and guided into the working space in the switching cylinder 30. The shift cylinder 30 retracts and synchronizes until the gear is fully engaged. The shift cylinder 32 remains in neutral position. After completion of the switching operation, all valves 34, 38 are returned to their original position.

Case 2: The piston of the shift cylinder 32 is to be completely extended in a standard operating phase and thereby switch a range group transmission 10. In this switching process, particularly strongly noise-developing components were identified and an experimentally determined control pressure stored in the system. Becomes the switching operation is started, the valve 34 and the valve 42 are actuated. The system pressure is detected by the pressure sensor 44 and the pressure is controlled so that the stored minimum control pressure is not exceeded or fallen below. The minimum drive pressure is fed into the pressure line 28, to the pressure port of the valves 34, 42 and into the working space in the shift cylinder 32. The shift cylinder 32 extends and synchronizes until the gear is completely switched. The shift cylinder 30 remains in the starting position. After completion of the switching operation, all valves 34, 42 are returned to their original position.

Case 3: A switching operation was initiated in a standard operating phase in which the piston of the shift cylinder 30 is to retract in the operating phase and the piston of the shift cylinder 32 is to extend completely. When switching the

Cylinder 32 were identified particularly strong noise-generating components. As a result, this operating phase was identified as having a particularly high degree of noise development and an experimentally determined activation pressure for the complete operating phase was stored in the system. When the switching operation is started, the valve 34, the

Valve 36 and the valve 42 is actuated. The system pressure is detected by the pressure sensor 44 and the pressure is controlled so that the stored minimum control pressure is not exceeded or fallen below. The minimum drive pressure is fed into the pressure line 28, to the pressure port of the valves 34, 36 and 42 and into the working space of the shift cylinders 30 and 32. The pistons of the shift cylinder 30 and shift cylinder 32 move parallel or successively in the direction of movement and

synchronize until the circuit is completely completed. After completion of the switching operation, all valves 34, 36 and 42 are returned to their original position.

Case 4: The piston of the shift cylinder 30 is to be completely extended during a slow drive while switching a gear of the main transmission 8. In this switching process, no particularly strong noise-developing components were identified. However, since the operating phase itself is a low-noise operating phase, an experimentally determined activation pressure for this switching process was stored in the system. When the switching operation is started, the valve 34 and the valve 38 are operated. The system pressure is detected by the pressure sensor 44 and regulated so that the stored minimum drive pressure is not over or is fallen short of. The minimum drive pressure is fed into the pressure line 28, to the pressure port of the valves 34, 38 and into the working space in the shift cylinder 30. The shift cylinder 30 extends and synchronizes until the gear is completely switched. The shift cylinder 32 remains in the starting position. After completion of the

Switching operation, all valves 34, 38 are returned to their original position.

REFERENCE CHARACTERS

G1 - G5 gears 1 to 5

RG reverse gear

S1 -S4 synchronization elements

6 Automated manual transmission

8 main gears

10 range group transmission

12 planetary gear set

14 clutch

1 6 vehicle drive

18 transmission input shaft

20 countershaft

22 main shaft

24 switching device

26 pressure supply

28 pressure line

30 shift cylinder main gear

32 shift cylinder transmission module

34 pressure valve

36.38 switching valve main gearbox

40.42 switching valve transmission module

44 pressure sensor

46 exhaust duct

Claims

claims

1 . A method for noise-optimized engagement of gears in an automated manual transmission (6) with pressure-actuated switching elements (30, 32), characterized in that starting from a

predetermined system pressure in the switching device (24) the pressure level of the switching device (24) is lowered for an upcoming switching operation to a value that is just enough for this switching operation to safely perform the switching operation.

2. The method according to claim 1, characterized in that the pressure of the switching operation of a strong noise-developing component or a strong noise-developing assembly is lowered so far that the noise is minimized.

3. The method according to claim 2, characterized in that the pressure is lowered in the operating phases in which at least one strong noise-developing component or assembly is involved and in all other

Operating phases without pressure reduction is switched.

4. The method according to any one of the preceding claims, characterized

characterized in that the switching pressure is minimized only in the quiet operating phases, such as standstill, slow driving or hybrid vehicles with deactivated combustion engine, and in all other

Operating phases without pressure reduction is switched.

5. The method according to claim 1 or 2, characterized in that the necessary minimum pressure is determined experimentally and adjusted.

6. The method according to claim 5, characterized in that the necessary sufficient minimum pressure adaptive, by assuming a very low

Pressure levels and gradually increase this pressure level, as long as to none functional limitations occur, determined and subsequently discontinued.

7. The method according to claim 5, characterized in that the necessary sufficient minimum pressure adaptively, by assuming a very high pressure levels and gradually lowering this pressure level, as long as no functional restrictions occur, determined and then adjusted.

8. The method according to claim 5, characterized in that the necessary sufficient minimum pressure is determined by means of sensors by the

Sensors measure the acceleration in the direction of adjustment of the actuator (30,32) and the resulting jerk when striking the actuator (30,32) and the process pressure is varied so long that reaches an acceptable impact noise and this is then adjusted.