DE19727595A1 - Starter motor system for internal combustion engine - Google Patents

Abstract

A starter motor system for an internal combustion engine with a dual mass flywheel monitors the variation of starter motor current with engine speed to determine the point at which the engine torque dominates i.e. the end of the starter motor drive. At this point the actual engine speed is compared with a reference speed. If it is greater than the reference speed the fuel feed is continued and the engine runs as normal. If the actual engine speed is below the reference level it indicates an excess of resonance in the system and the fuel feed is stopped to abort the start. The reference speed is determined by the engine parameters and the temperature of the engine coolant. The safety system is readily applied to fuel injection engines.

Description

The invention relates to a method and an apparatus for starting Internal combustion engines with a dual-mass flywheel to avoid start-up resonances.

To improve the running behavior of internal combustion engines, in particular engines in motor vehicles, it is known to rigidly assign a mass flywheel so that an overall calmer running behavior arises.

Due to the increasingly ergonomic design of motor vehicles, the natural Attenuation of the motor vehicle from, whereas the number of noise sources steadily increases. For example, the gas forces generated by combustion are particularly low Speeds a non-uniform torque on the crankshaft and the flywheel, which creates torsional vibrations that are transmitted to the transmission and the clutch Powertrain are transmitted. As a result, gear rattling occurs at idle and in pull and push operation at low speeds. To isolate the vibrations The engine has therefore developed dual mass flywheels, in which one mass the moment of inertia of the motor and the other mass only the moment of inertia is assigned to the transmission. The two decoupled masses are connected via one Spring / damping system. Due to the increased moment of inertia Gearbox components only take these at significantly lower speeds below the Idle speed vibrations. The resonance peaks and so on connected torque peaks, however, the stronger the larger the vibrating ones Masses are so that they occur especially when starting the engine. Device that Torsional vibration system in resonance, so the engine gets stuck at this speed and the high torques that occur in the dual-mass flywheel result in a very short time Time to destroy it if the engine is not turned off.  

An additional damping device is known for avoiding these starting problems to be provided, which is only switched on in the start phase. However, in normal operation this additional damping device out of function, and the torsional vibrations of the Motors are filtered out by the spring damper. For optimal vibration isolation and the smooth resonance passage when starting and stopping the engine must Ratio of friction and spring rate can be chosen optimally. Of crucial The length of the springs is important because the softer a spring is, the better the vibrations are isolated. The disadvantage of this type of resonance suppression is that the softer the springs are, the lower the component strength. Furthermore this also leads to a deterioration in the vehicle acoustics.

For this reason, injection engines have gone over to starting resonance Measures to compensate for the engine control unit. To do this, an injection of Fuel at start-up only above one, depending on the water temperature of the cooling water, limit speed. This ensures that Torsional vibration system after the first combustion of a cylinder Speed has reached which is above the resonance speed. Disadvantage of that known method is the noticeably higher start time from the start of the starter activation until to reach the idling speed, because only above the limit speed mentioned Combustion takes place. As the limit speed is proportional to the engine torque the development of motors with larger moments to further deteriorate the start times.

The invention is therefore based on the technical problem, a method and a To provide a device for starting an internal combustion engine with a dual-mass flywheel, by means of which an improvement in the starting times of the internal combustion engine can be achieved.

The solution to the technical problem results from the features of the claims 1 and 3.

By determining the end of starter actuation from the gradient of Starter battery voltage and / or the starter actuation signal can directly with the Starter actuation signal can be started with the fuel supply, which the Startup process accelerated considerably. It is only checked when the starter activation has ended  the speed of the motor is dependent on a state parameter of the motor Has exceeded the limit or not. If this limit is exceeded, the Starting process can be continued without risk of a start resonance. Otherwise the Starting process interrupted by the engine control unit interrupting the fuel supply. The The advantage is that the starting behavior of the engine is only affected if the There is a risk of initial resonance. Otherwise, the starting process is no different from that of a vehicle with a conventional clutch and rigid flywheel. Due to the Shorter actuation times with a warm engine increases the lifespan of the starter. Furthermore, the energy consumption is reduced by the shorter start times and the The possibility of short start resonances with a short activation of the starter is avoided. In addition, the starting process can also take place at lower starter battery voltages. Another advantage is that no additional external wiring is necessary if that End of starter actuation from the gradient of the starter battery voltage from Engine control unit is derived. Further advantageous embodiments of the invention result from the subclaims.

The invention is explained in more detail below on the basis of a preferred exemplary embodiment explained. The single figure shows a schematic block diagram of the device for Starting a motor vehicle engine with a dual mass flywheel.

The device 1 for starting a motor vehicle engine 2 with a dual-mass flywheel comprises a starter battery 3 , a starter device 4 , an engine control unit 5 and a fuel supply device 6 . The starter battery 3 can be connected to the starter device 4 , which comprises a DC motor. The DC motor is operatively connected to the motor vehicle motor 2 and rotates it during the starting process. If the starting process is initiated by actuation of the ignition key, the starter device 4 receives a starter actuation signal 7 and the DC motor is switched on by the starter battery 3 . The engine control unit 5 generates a fuel supply signal 8 , which is transferred to the fuel supply device 6 . The fuel supply device 6 is activated and supplies fuel to the individual cylinders. At the same time, the engine control unit 5 detects a water temperature T _{W of} the cooling water of the motor vehicle engine 2 and determines an associated limit speed n _GR from a map. Furthermore, the engine control unit 5 detects the respective speed n of the motor vehicle engine 2. The end of the starter actuation can be derived from the engine control unit 5 from the gradient of the starter battery voltage. Alternatively, the starter actuation signal 7 could also be fed directly to the engine control unit 5 , which would, however, result in additional wiring. If the engine control unit 5 now detects or determines the end of the starter actuation, the current speed n of the motor vehicle engine 2 is compared with the limit speed n _GR . If the speed n is greater than the limit speed n _GR , the starting process is continued until the speed n has reached the start release speed. Otherwise, the starting process is interrupted by the engine control unit 5 switching off the fuel supply device 6 . This can be implemented very easily, in particular in motor vehicle engines 2 with electronic injection control, since these already have a connection to engine control unit 5 .

Reference list

1

contraption

2nd

Motor vehicle engine

3rd

Starter battery

4th

Starter device

5

Engine control unit

6

Fuel supply device

7

Starter actuation signal

8th

Fuel supply signal

Claims (4)

1.Device for starting an internal combustion engine with a dual-mass flywheel, comprising a starter device, a starter battery which can be acted upon by the starter device, an engine control unit and a fuel supply device which can be controlled by the engine control unit, the speed n and at least one further state parameter of the internal combustion engine can be determined, from which a limit speed in the engine control unit n _{GR can be} derived, characterized in that the engine control unit ( 5 ) comprises a device for detecting the gradient of the starter battery voltage and / or the starter actuation signal ( 7 ), by means of which the end of the starter actuation can be derived and the fuel supply device ( 6 ) depending on the detected speed n to the limit speed n _GR at the end of starter actuation, a control signal can be supplied. 2. Device according to claim 1, characterized in that the further state parameter is the cooling water temperature T _W. 3. Method for starting an internal combustion engine with a dual-mass flywheel, by means of a starter device ( 4 ), a starter battery ( 3 ), an engine control unit ( 5 ) and a fuel supply device ( 6 ), comprising the following method steps:

• a) emitting a starter actuation signal ( 7 ) to the starter device ( 4 ),
• b) delivery of a fuel supply signal ( 8 ) from the engine control unit ( 5 ) to the fuel supply device ( 6 ),
• c) detection of the rotational speed n and at least one further state parameter of the internal combustion engine by the engine control unit ( 5 ),
  The engine control unit ( 5 ) determines a limit speed n _{GR as} a function of the state parameter,
• d) detection of the gradient of the starter battery voltage and / or the starter actuation signal ( 7 ) by the engine control unit ( 5 ) to determine the end of the starter actuation,
• e) comparison of the detected speed n of the internal combustion engine at the end of starter actuation with the determined speed limit n _GR and
• f) Continuation of the starting process if the speed n of the internal combustion engine is greater than the limit speed n _GR at the end of the starter actuation or termination of the starting process by switching off the fuel supply by means of the engine control unit ( 5 ) if the limit speed n _{GR is} undershot.

4. The method according to claim 3, characterized in that the water temperature T _{W of} the cooling water is detected as the state parameter of the internal combustion engine.