EP1270933A1 - Control method for the torque of a starter - Google Patents

Abstract

The method involves detecting the revolution rate of the internal combustion engine (1) being started using revolution rate sensors (7) and changing over from an initial torque control method (4a) without revolution rate feedback to a method (4b) involving revolution rate feedback depending on at least one engine operating parameter. <??>AN Independent claim is also included a vehicle drive arrangement.

Description

The invention relates to a method for controlling the torque output Starter during the start of an internal combustion engine coupled to the starter. Furthermore, the invention relates to a vehicle drive containing one Internal combustion engine, a starter coupled to the internal combustion engine and a controller to control the torque output of the starter during the starting process of the internal combustion engine.

Motor vehicles with an internal combustion engine generally have a starter or Starter on, with the help of the engine is started. Are currently Starter engines in development, by means of which an internal combustion engine within less milliseconds from standstill to idle speed, for example 800 rpm can be brought. Such electrical machines are common combined with a generator function, which is why these are also used as (integrated) starter generators (English: starter generator S / A).

Such starter generators are known, for example, from US Pat. No. 6,073,713 and US Pat US 6 002 219 known. Furthermore, EP 0 903 492 A2 describes a control method known a starter generator, in which a controller during starting the engine, torque output from the starter controlled. The coolant temperature of the internal combustion engine monitors and with a cold engine a lower power output of the electrical Machine specified. This measure aims at changing behavior a cold internal combustion engine compared to a warmed up internal combustion engine be reacted to.

The performance of modern electrical machines can be used to: the internal combustion engine during short downtimes, for example in front of a traffic light, switch off and thereby save fuel. The The starter's quick reaction enables a quick restart the internal combustion engine, so that there is a quasi-instantaneous start-up can. That while starting from the starter to the internal combustion engine The torque output is dependent on certain operating parameters controlled according to a predetermined torque curve in order To avoid damage and a quick and comfortable start of the Ensure internal combustion engine. Such a regulation of the torque output the starter is usually fed back based on a measurement the engine speed reached. However, the problem arises on that the circuits used in practice for speed detection Engine speed only above a certain speed threshold and with a certain Can recognize time delay. This time delay arises, among other things. through the acquisition of the raw data, through the subsequent signal filtering and due to transmission delays. All influencing factors together can a speed detection, in which the first usable speed signal only is available very late. Typically, the desired idle speed 70% have already been reached before the first signals are available.

Against this background, an object of the present invention was a method and an apparatus for controlling the torque output of a Provide starter, through which or through which an improved and safer starting behavior while maintaining the known speed measurement methods is guaranteed.

This object is achieved by a method with the features of the patent claim 1 and by a vehicle drive with the features of the claim 5 solved. Advantageous refinements are contained in the subclaims.

The method according to the invention for checking the torque output of a Starter, especially a starter of the powerful type of starter generator, during the starting of an internal combustion engine coupled to the starter is based on the fact that speed sensors measure the speed of the Detect internal combustion engine. Depending on at least one engine operating parameter - e.g. of the reached and signaled by the speed sensors Engine speed - is in the process of one initially carried out, non-feedback control of the torque output, where the speed signal is not taken into account, to a feedback control of the torque output switched, in which the speed signaled by the speed sensors is taken into account.

In contrast to the known methods, the method explained thus works during of the starting process is not continuous with a feedback control. Rather, such a regulation initially goes into a phase with no feedback Control ahead. This control phase extends at least to the period in which the speed sensors are still not usable Speed signal is provided. Instead of - as with conventional feedback Regulations known - with a faulty speed signal during this period to work, is not on the speed signal in the inventive method resorted to and instead a non-feedback control performed. This allows better starting behavior of the starter achieve than with a feedback control with possibly incorrect sensory inputs. As soon as signals usable by the speed sensors can be switched to the feedback control, their proper function is then ensured.

The control, which is not fed back, preferably gives purely time-dependent control signals to the starter. This means that the control signals as time sequences in the Control are stored and their course neither from the speed nor from other Variables depends on the time. The one for a particular vehicle drive The person skilled in the art can achieve optimal control processes through theoretical calculations or win with the help of simple experiments.

The feedback control in the second phase of the starting is preferably carried out depending on an error signal which is defined as the Difference between a predetermined desired speed curve and the measured speed. Since the measured speed in the second phase of the The engine can be reliably provided by the speed sensors Control minimize the error signal mentioned so that the speed of the internal combustion engine follows the specified speed curve in the best possible way.

Switching from the non-feedback control to the feedback Control is advantageous when a predetermined speed is reached performed. The speed signals are used to reach this speed monitors the speed sensors. It must be ensured that this speed signal is only used when it is stable and has reached reliable value.

Alternatively, however, other engine operating parameters can also be used for initiation the switchover are used, the engine operating parameters being e.g. the elapsed time since the starter was started or a signal from the torque sensors regarding the validity of the determined torque signals etc. can be used.

The transition between non-feedback and feedback operation can can be designed by a damping term in the feedback controller, that too fast rule jumps or overshoots are avoided.

The invention further relates to a vehicle drive which has an internal combustion engine, a starter coupled to the internal combustion engine, a regulator to control the torque output of the starter during the starting process the internal combustion engine and at least one coupled to the controller Includes speed sensor for detecting the speed of the internal combustion engine. The mentioned controller is set up so that it is a method of the above Type can perform. That means that the controller functionally consists of two modules exists, one of which is a non-feedback control during the first phase of starting and the second a feedback scheme during the subsequent second phase of starting. The regulator can also be designed so that the preferred embodiments of the method explained.

The starter of the vehicle drive according to the invention is preferably an integrated starter generator. Such a starter generator has significant advantages and enables due to its performance fuel-efficient operation of the vehicle. At the same time it is with one such electrical machine, however, required the torque output Check as closely as possible during the starting process to avoid damage submissions.

Fig. 1

eine schematische Darstellung der Komponenten eines erfindungsgemäßen Fahrzeugantriebs; und

Fig. 2

eine schematische Darstellung des Drehzahlverlaufs während des Anlassvorganges.

The invention is explained in more detail below using the figures as an example. Show it:

Fig. 1

a schematic representation of the components of a vehicle drive according to the invention; and

Fig. 2

a schematic representation of the speed curve during the starting process.

The vehicle drive shown in FIG. 1 contains an internal combustion engine 1, which drives an output shaft. There is an electrical machine on the output shaft 2 arranged in the form of a starter generator, which both as a motor can also be operated as a generator. The output shaft of the machine 2 is coupled via a clutch 3 to a transmission 5, through which various Translations can be set. On the exit side of the Transmission 5, the drive torque is passed on to the wheels 6 of the vehicle. The clutch is during the starting process of the internal combustion engine 1 3 opened to internal combustion engine and starter from the transmission 5 separate.

The starter generator 2 is a modern type of electric machine which is so powerful that the internal combustion engine 1 can be started within milliseconds. In order to avoid damage occurring and disadvantageous behavior, the starter 2 is controlled by a controller 4. The controller 4 receives a speed signal from the speed sensors 7 arranged on the internal combustion engine 1, which indicates the current speed n of the internal combustion engine 1. It should be noted, however, that when the internal combustion engine 1 is started, a usable speed signal is provided by the speed sensors 7 only after a very long delay due to technical effects. This situation is illustrated schematically in FIG. 2. Fig. 2 shows a typical course of the speed n (vertical axis) over time t (horizontal axis) during a starting process. It can be seen that the first usable speed signal n _{1 is} only available when the speed has already reached approximately 70% of its maximum value, ie the idling speed n _idle . For most of the starting process, the controller 4 thus has no usable speed signal.

While in conventional regulators a feedback regulation of the torque output of the machine 2 takes place, the regulator 4 according to the invention contains three different modules for fulfilling the regulation task. The first module 4a corresponds to a feedback control which receives as input signal an error signal which is defined as the difference between the measured speed n and a target speed curve n _d . In addition, however, a module 4b is also provided for carrying out a non-feedback control, the output signal of which depends solely on the time t. The changeover between the two modules 4a, 4b mentioned is carried out by a selection module 4c, which in the first phase of the starting process passes the control signal of the non-feedback control 4b and in the subsequent phase of the starting process the control signal of the feedback controller 4a to the machine 2. The switchover module 4c monitors the speed signal and makes the switchover at the moment when a first (usable) speed signal is detected.

Due to the two-part mode of operation of the controller 4, a better overall Check control of electrical machine 2, as not with faulty ones Speed signals in the first phase of cranking is worked.

Claims (6)

Method for checking the torque output of a starter (2) during the starting process of an internal combustion engine (1) coupled to the starter, wherein speed sensors (7) record the speed (s) of the internal combustion engine, characterized in that , depending on at least one engine operating parameter, an initial one , with respect to the speed of the feedback control (4b) of the torque output is switched to a feedback control (4a) of the torque output. Method according to Claim 1, characterized in that purely time-dependent control signals are emitted to the starter (2) in the non-feedback control (4b). Method according to Claim 1 or 2, characterized in that the feedback control (4a) takes place as a function of an error signal consisting of the difference between the measured speed (n) and a predetermined speed curve (n _d ). Method according to one of claims 1 to 3, characterized in that a switch is made from the non-feedback control (4b) to the feedback control (4a) when a predetermined speed is reached. Vehicle drive containing a) an internal combustion engine (1), b) a starter (2) coupled to the internal combustion engine, c) a controller (4) for controlling the torque output of the starter (2) during the starting of the internal combustion engine (1), d) a speed sensor (7) coupled to the controller (4) for detecting the speed of the internal combustion engine (1), characterized in that the controller (4) has a control module (4b) for a non-feedback control of the torque output of the starter and a control module (4a) for feedback control depending on the speed of the internal combustion engine, and a switchover unit (4c) which is activated during the starting process depending on at least one engine operating parameter, the control is switched from the non-feedback control module (4b) to the feedback control module (4a). Vehicle drive according to claim 5, characterized in that the starter is an integrated starter generator (2).

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