WO2001073321A1

WO2001073321A1 - Control for an automatic transmission

Info

Publication number: WO2001073321A1
Application number: PCT/DE2000/000903
Authority: WO
Inventors: Ernst Nock; Johann Wild
Original assignee: Siemens Aktiengesellschaft
Priority date: 2000-03-24
Filing date: 2000-03-24
Publication date: 2001-10-04
Also published as: DE10084615D2

Abstract

The invention relates to a control for an automatic transmission, comprising a gear-shift gate (14) with positions that can be used to determine the gear positions and the neutral position. A gear shift actuator (35) approaches a position with a predetermined speed and shifts the gear. The control (8) comprises a control circuit (36) that controls the amount of the actuating force (F) and the time for which it is applied.

Description

description

Control for an automated manual transmission

The invention relates to a control according to the preamble of claim 1. Such a control is used to control an automated gearbox of a motor vehicle drive. It contains a shift gate that has positions by which the gear positions and the neutral position of the transmission are determined, and gear actuators by means of which one of the positions is approached with a given path and a given speed and the gear determined by the control is engaged.

Automated manual transmissions (also: automatic manual transmissions) have recently been increasingly used, in particular in motor vehicles in the lower and middle classes, in which fully automatic transmissions have so far not been very widespread, at least in Europe. They require less effort and are lighter than conventional automatic transmissions, but with a suitable design allow comparable driving comfort (see Mannesmann "Automatic actuation systems", from the Internet from March 7th, 2003 at http: // www.sachs-ag. De / German / drive / car system.html, pages 1-3).

For an economical and comfortable shifting behavior of such a transmission, it is important to be able to specify different target functions for controlling the gear actuators. They are currently only controlled in a simple manner depending on positions and short-term speed profiles with regard to only one target function.

The invention has for its object to provide a controller for an automated manual transmission, which a control gear actuators with regard to different target functions, taking into account environmental influences, driving situations and physical state variables characteristic of driving operation.

The object of the invention is achieved by a control according to claim 1. Appropriate developments of the invention are set out in the subclaims.

The advantages of the invention are, in particular, that fast gear changes are only requested when they are really needed, as a result of which very short shifting tents are achieved with little wear on the transmission.

Exemplary embodiments of the invention are explained below with reference to the drawings. Show it:

FIG. 1 shows a motor vehicle drive with a control according to the invention for an automated manual transmission;

FIG. 2 shows a shifting gate of the automated manual transmission according to FIG. 1; Figure 3 is a structural diagram of the controller of Figure 1; 4 shows the course of the Aktuatorgeschwmmdigkeit when switching the automated manual transmission according to Figure 1;

5 shows the course of the to be applied when changing gear

forces; FIG. 6 shows a control loop of the control according to FIG. 1, and FIG. 7 shows a flow diagram of a program processed by the control according to FIG. 1.

A motor vehicle drive 1 (FIG. 1) - insofar as it is important for the present invention - has the following components: a motor 2, a clutch 3, a clutch actuator (also as an actuator or actuator for denotes the clutch) 4, a manual transmission 5 (hereinafter also referred to as a transmission for the sake of simplicity), a transmission actuator 6, an electronic control 8 for the actuator 4 and the transmission actuator 6 and a motor control 9. The electronic control 8 is included the actuator 4 by control and signal lines 10 and connected to the transmission actuator 6 by control and signal lines 11. It fulfills both the functions of a clutch control, which is not of interest here, and that of the transmission control described below. The gear actuator 6 contains two gear actuators to be described in detail (see FIG. 3), by means of which the gear is brought into the new gear position or into the neutral position (idling) when shifting.

The actuator 4 can be designed as an electric motor-driven or as a hydraulically driven actuator. In the present exemplary embodiment, a hydraulic actuator 4 is used, which is connected to the clutch 3 by a pressure line 12.

In the motor vehicle drive 1, in the present exemplary embodiment, the manual transmission 5 is designed as an automatic (or also: automated) manual transmission ASG. The switching commands are either from the electronic

Control 8 generated or entered manually by the driver, for example via a known tip switch. The clutch 3 is automatically actuated, likewise controlled by the electronic control 8, both when starting the motor vehicle and when changing gear in the manual transmission 5.

A shifting gate 14 (FIG. 2) of the manual transmission 5 contains positions or shift positions 1, 2, 3, 4_ and _5 which correspond to the first to fifth gear of the transmission 5, a position position R for reverse gear and a position N or neutral for neutral. Positions 1 and 2, as well as positions _3 and 4_ each form an aisle, as do position _5 and position R. The neutral position N lies in the connecting line of the other positions.

The neutral position or a new gear position is approached with the two gear actuators mentioned, one of which, for example, moves in the x direction and the other in the y direction and thereby shift sleeves in the transmission. A distinction is made between circuits without a change of lanes (for example 1_ -> 2) and circuits with a change of lanes (for example 2 -> _3). Overall, at least the following requirements for the dynamic sequence of a gear position change must be met:

• As short a time span as possible to bridge the path between a first and a second gear position

• The lowest possible mechanical stress on the gearbox (caused by friction and high forces)

• A low level of noise, especially when changing gears

A switching force F, which corresponds to the force to be overcome when changing gears, serves as actuating force for moving to the different gear positions and engaging the gears (see also FIG. 5).

The electronic control 8 contains a superordinate control block 16 (also referred to as a SAT module), a switch manager 17 (also referred to as an AMT manager or AMT module), which is connected to the engine control unit 9 (EMS) via a data bus 18, and an actuator control 20 (also referred to as an ACS module). The control block 16 defines the driving strategy for the motor vehicle drive, depending on various influencing variables and on the driving style of the driver. The shift manager 17 coordinates the shift processes and also acts on the engine control in order to avoid, among other things, shift jerks by influencing the engine operating state (speed and torque). The actuator controller 20 contains a control circuit for controlling the gear actuators, which is explained on the basis of the following figures.

The superordinate control block 16 transmits a short-term interpretation of the accelerator pedal actuation acc short and a long-term interpretation of the accelerator pedal actuation acc_long to the actuator control 20 via a line 21. It transmits a gear suggestion to the shift manager 17 via a line 22. The shift manager 17 uses this gear suggestion and engine operating data that he receives from the engine control 9 to determine a target gear, that is, the new gear to be engaged, and transmits it to the actuator control 20 via a line 23, which determines the values based on the target gear associated target currents for controlling the gear actuators and regulating them with the control loop contained in them.

The target currents arrive via lines 24 to an electronic end stage or driver stage 26 (BIOS / hardware), which generates corresponding valve currents and controls hydraulic valves 28 to 31 with them via lines 27 and thus actuation pressures, which are represented by arrows 32, for the Emzel gear actuators generated. The Emzel gear actuators are represented by switching or actuator force components F _2B to F ₃₁ generated with the actuation pressures. F ₂ s and F _{29 represent,} for example, a first gear actuator which shifts in the x direction and is flowed against by the hydraulic valves 28 and 29. F ₃₀ and F ₃₁ represent a second gear actuator, which shifts perpendicularly thereto, that is to say in the y-direction, and against which the hydraulic valves 30 and 31 flow. Together, both gear actuators determine a controlled actuator position 34 and thus the engagement and disengagement of the respective undulating transmission gear or the neutral position of the transmission.

The Emzel gear actuators F ₂₈ to F _{3X collectively} result in a (total) gear actuator or gear actuator 35, which generates a (total) shifting force F, which is the manipulated variable when controlling the manual transmission 5. With this shifting force, the gear actuator 35 is accelerated and decelerated, thus achieving a variable shifting speed. Coordinated switching on of the hydraulic valves 28 to 31 (or of stepper motors in the case of an electric motor-driven gear actuator) influences the movement curve which the gear actuator travels on the way from a gear position A to a gear position B ( see Figure 2).

An advantageous speed profile for the actuator movement, that is to say the course of the actuator speed v over the path x of the actuator movement, can be seen from FIG. The movement of the gear actuator 35 begins from the idle state with an initial speed v_start = 0 (corresponds to point A in FIG. 2) and initially rises rapidly; the acceleration force required for this can be seen in FIG. 5. In the next phase of the movement there is practically no resistance to overcome in the gearbox, the speed remains high. When approaching the synchronization point, the speed is reduced because it should not be approached too quickly. To synchronize, force must be used again. In the subsequent phase, the speed increases again until it is reduced again shortly before engaging the gear, while the required force increases. The movement of the gear actuator 35 finally ends with a final speed v_end = 0 (point B in FIG. 2).

If there is a speed difference delta_n between the transmission output and input, the gear change is Chroming position of the gearbox stopped by the lock synchronization and until the speeds have equalized. It is important that the synchronization position is approached at a speed that is not too high.

If the actuator speed is too high when shifting into gear, this is noticeable through increased noise development and greater wear during ratcheting, ie when a gear engages in its end position, the gearbox. Otherwise, only empty paths need to be bridged when changing gears, which means that the gear change should be carried out at the highest possible speed. Because of these circumstances, controlling the actuator speed during the entire gear change is very advantageous. Accurate control of the neutral position is important if it is the target position. In this case it must be avoided that when synchronizing the gear, the synchronizing device of the adjacent gear is reached by overshooting beyond the neutral position.

FIG. 5 shows the forces that have to be overcome when changing gear in the driving state - that is to say with a speed difference between the transmission input shaft and the transmission output shaft (also called transmission output shaft). A certain minimum force is required to disengage a gear. There are four characteristic positions that are essential for a gear change: gear position 1, the neutral position, the synchronizing position and the gear engagement position (also known as a grid).

Other physical variables that are taken into account when changing gears are the transmission temperature and the speed difference between the transmission output and the Transmission input shaft, and also parameters of a so-called driving strategy, as described in the older patent application DE 99114644.0 (our file number GR 99 P 2364). These include, for example, a so-called sportiness factor, which results from a long-term analysis of the accelerator pedal dynamics, and a factor that reflects the current driver's desired torque, derived from the short-term accelerator pedal interpretation with the associated signal processing.

In addition, there are some boundary conditions to be observed, such as:

F <Fmax, and

F * r * delta_n <P ax where Fmax is the maximum shifting force permitted for the respective transmission, r is a constant factor with the dimension of a radius, delta_n is the speed difference between the transmission input shaft and the transmission output shaft and Pmax is the maximum permitted synchronization power.

The gear actuators are controlled in a closed control circuit 36 (FIG. 6). A guide and a speed specification, which are provided for the gear change, serve as guide sizes 37. The guide sizes 37 depend, for example, on the parameters of the driving strategy acc_short, acc_long, which are transmitted by the control block 16, on the speed difference delta_n between the transmission input and transmission output shaft, taking into account the translation, and on the type of shift, that is, whether it is an upshift or a downshift (shιft_up, shιft_down). The guide variables 37 pass through an adder 38, to which the respective actual value is returned with a negative sign, as an actuating variable m, an actuator 39 which controls the gear actuator 35 with the amount of the actuating or switching force and the time at which the actuating force is effective, and thus the Way and affects the speed of the gear change. As already mentioned, the actuator expediently consists of two Emzel actuators, one for the movement m x direction and one for the movement m y direction.

The output signal of the actuator is influenced by an adder 40 from disturbance variables, such as the temperature, and reaches a measuring device 41, shown as a block, which summarizes the position and speed sensors of the manual transmission 5, which are not shown in detail. The output signal of the measuring device 41, which represents an actual position or a rotational speed value, is fed back to the adder 38 via a feedback loop 42 and is subtracted there from the corresponding guide variable 37.

The synchronization phase when shifting the transmission is a special case. If there is a speed difference between the transmission input shaft and the transmission output shaft taking into account the translation, the movement of the gear actuator at the synchronization position is interrupted and only continues when the Have adjusted speeds by the synchronizer. The synchronization force and the resulting synchronization speed are also controlled depending on the parameters of the driving strategy.

As already mentioned, there are at least three target functions according to which the shift behavior of the transmission can be optimized, but which contradict each other. It is therefore not possible to change gear positions both as quickly as possible and as little wear as possible. That is why the leadership-sized actuator speed v and switching path s are controlled depending on the driving situation and the speed difference. For example, if you accelerate a lot when accelerating, so uss are trying to change gear as quickly as possible to keep an interruption in traction as short as possible. However, in the case of a downshift, for example from third to second gear, it is not necessary to achieve the smallest possible gear change time. When the motor vehicle is at a standstill, a quick gear change is generally not necessary.

Since a gear change takes place very quickly (e.g. in 100 ms with a change of lanes) and the hydraulic or electromotive gear actuator 35 is subject to certain dead times, it is useful to evaluate the gear change after each gear change by determining the deviation between the target specification and the actual progress and in the event corrections are made for deviations in the subsequent switching operation.

A program executed by the electronic control 8 when the transmission 5 is shifted (FIG. 7) has the following steps:

Sl: Start of a control loop to be cycled. S2: There is a path and a speed specification

(Setpoints) for the gear actuator, depending on the speed difference delta_n, the short-term interpretation acc_short and the long-term interpretation acc_long of the accelerator pedal actuation and the shift type shift_up_down. S3: The differences between the target or target sizes and the associated actual sizes are formed. S4: The required actuator force is determined according to the amount and time of activation. S5: The position and speed of the gear actuator are measured. The program then jumps back to step S1. The control described above for an automated manual transmission 5 enables the fastest gear change times, but also ensures that these are only carried out for gear changes for which they are also necessary. On the one hand, this enables fast gear changes and, on the other hand, has a very advantageous effect on the durability of the transmission.

Claims

claims

1. Control for an automated gearbox (5) of a motor vehicle drive (1) with a shift gate (14), the positions (_l-5, R, N) through which the gear positions and the neutral position of the transmission are determined, and with at least a gear actuator (35), by means of which one of the positions is approached with a given path and a given speed and the gear determined by the control system is engaged, characterized in that the control system (8) contains a control circuit (36) through which the amount of the actuating force (F) of the individual gear actuator (35) and the time course of this actuating force (F) are regulated depending on specifications.

2. Control according to claim 1, characterized in that specifications for the control circuit (36) are a target position and a speed profile of the actuator (35), which depend on the speed difference (delta_n) between the transmission input shaft and the transmission output shaft, on the type of Gear shift (shift_up, shift_down) and depend on the type of accelerator pedal actuation (acc_short, acc_long).

3. Control according to claim 1 or 2, characterized in that it has a higher-level control block (16) through which the

Driving strategy for the motor vehicle drive (1) is determined, and contains a shift manager (17), through which the shifting operations of the manual transmission (5) are coordinated.

4. Control according to claim 3, characterized in that a gear suggestion is generated by the higher-level control block (16) and transmitted to the shift manager (17).

5. Control according to claim 1, characterized in that it has an actuator control (20) in which the control circuit (36) is contained and which information from a higher-level control block (16) about a short-term interpretation of the accelerator pedal actuation (acc_short) and a long Time interpretation of accelerator pedal actuation (acc__long) received.

6. Control according to claim 1, characterized in that it has an actuator control (20) which receives information about the target gear from a shift manager (17).

7. Control according to claim 1, characterized in that an actuator control (20) determines target currents on the basis of information received and is transmitted to electrohydraulic valves (28-31) via a driver stage (26).

8. Control according to claim 3, characterized in that the shift manager (17) is connected to an engine control (9) via a data bus (18), via which the engine operating state is influenced when switching.