DE19538308A1 - Method for controlling speed of IC engine - Google Patents

Abstract

The method for speed control determines the engine and gearbox input shaft speeds, the accelerator pedal deflection, the engaged gear and the clutch position. During gearchange, the engine speed is automatically adjusted to a synchronous speed (NS) dependent on the vehicle speed and engaged gear. The engine speed is held at this synchronous speed either until the clutch is re-engaged or for a preset time period if the clutch remains released or the gearbox is placed in neutral. Thereafter the engine speed returns to accelerator pedal operation. Pref. the time period is between 200 and 500 milliseconds.

Description

The invention relates to a method for controlling the speed of an internal combustion engine during a switching operation of a manual transmission according to the preamble of the patent claim 1.

For performing switching operations in motor vehicles with mechanical switching driven it is known that the clutch to initiate an upshift or downshift pedal depressed and thus the between the gearbox and the engine orderly drive clutch opened, and the accelerator pedal returned in its deflection is taken. The new gear is mechanically engaged by the driver to downshift as well as the clutch pedal then withdrawn and the accelerator pedal off again directed. For a comfortable engagement, the engine and transmission must be identical gear shaft speed can be reached. If this speed synchronism is not achieved, then the engine speed is adjusted to the speed of the gearbox by grinding the clutch gear shaft adapted, which ultimately produces a high braking torque in the clutch is synonymous with high clutch wear.

The situation is similar with the upshift, with the clutch pedal depressed and withdrawn accelerator pedal (closed throttle valve) the engine speed quickly falls off. For a comfortable engagement after mechanical switching, the Engine speed and the transmission input shaft speed almost at the time of engagement be equal. Here too, synchronicity is not always possible, even with experienced drivers guarantee.

Against this background, DE-OS 39 37 302 describes a method for switching a Unsynchronized claw manual transmission known, among other things for the manufacture the desired speed synchronism between the internal combustion engine and transmission for a Upshift the engine speed for a short time by automatically controlled or regulated Actuation of the engine brake and simultaneous decrease in fuel injection quantities  throttles and for a downshift the engine speed for a short time by especially au Automatically controlled or regulated increase in fuel injection quantity increased the. Then, if the speed synchronism is detected by sensors, the for the Switching relevant gears of the gearbox in operative connection with each other brought. However, there is the coupling between the gearbox and the internal combustion engine always closed.

Knowing this prior art, the object of the invention is for a Drive arrangement with an internal combustion engine and a manually operable hand manual transmission and one arranged between the internal combustion engine and the transmission ten manually operable drive clutch to present a method with which the addressed automatic speed synchronism during upshifts or downshifts is adjustable. The solution to this problem results from the features of the claim 1, while advantageous embodiments of the invention can be found in the subclaims are.

The invention is based on the idea that the combustion during the switching process engine speed automatically and therefore independently of that by the driver desired driving performance signaled by the accelerator pedal deflection is set. The Driving speed-dependent synchronous speed between the internal combustion engine and Ge Drives is from a control device during the switching process for a Predeterminable period of time by influencing the power actuator (Throttle valve) set and held. After engaging the new gear the Control of the speed or power specification by the accelerator pedal again. Provided the control device by appropriate sensor information (Gear selector lever sensor, accelerator pedal sensor) learns that the shifting process is canceled and to be returned to the previous gear, the speed is reduced to that by the Accelerator pedal position and the current driving situation given engine speed leads.

The invention can be explained using an exemplary embodiment, to which also the Description attached drawing can be used. Show in it

Fig. 1 is a schematic representation of the drive assembly,

Fig. 2 is a circuit diagram of the high speed characteristic of the engine and the course of the operation state of the accelerator pedal in an unregulated upshift,

Fig. 3 is a diagram according to Fig. 1, but with controlled upshift,

Fig. 4 is an illustration as in Fig. 2, but for a downshift, and

Fig. 5 is an illustration as in Fig. 3, but for a downshift.

In Fig. 1, the reference numeral 1 denotes an internal combustion engine, the crank shaft 2 with a mechanically activated by a clutch pedal actuation driving clutch 3 is connected. Also with this clutch 3 , the transmission input shaft 4 of a mechanically switchable transmission 5 is connected, which in turn is connected via a transmission output shaft 6 with a differential gear 7 . From this differential gear 7 axle shafts 9 go to the vehicle wheels 10 to be driven. This drive arrangement is associated with a control unit 11 , which is connected via control or sensor lines shown in dashed lines to sensors and actuators in the drive arrangement. This control unit 11 is connected to an actuator of the throttle valve 13 or the fuel injection pump of the internal combustion engine 1, while it communicated 12 of the transmission 5, and / or by means of a speed sensor 17, the rotational speed of the transmission input shaft 4 by ei NEN sensor 14 the position of the gear selector lever. With the help of the speed sensors 15 , 8 , the speeds of the crankshaft 2 and the gearbox input shaft 6 are determined. The control unit is informed of the actuation state of the clutch 3 via a sensor 16 . Finally, an actuating angle sensor 19 is provided on the accelerator pedal 18 , which transmits the current accelerator pedal deflection to the control device.

In normal driving operation, the accelerator pedal 18 is used to inform the control unit 11 of the driver's power request of the motor vehicle via the sensor 19 and is signaled in a control signal for the actuating means on the throttle valve 13 or the fuel injection pump on the internal combustion engine. If the initiation of a gear change is determined with the help of sensors 16 (actuation of clutch 3 ) and 14 (actuation of gear selector lever 12 ) or 16 (actuation of clutch 3 ) and 17 (change in speed of transmission input shaft 4 ), then the shift process takes place for the period of time the signal from the sensor 19 via the accelerator pedal position is ignored by the control unit and, depending on the determined upshift or downshift request and the current driving speed, by appropriate actuation of the throttle valve 13 or the fuel pump on the internal combustion engine, the engine speed is set to achieve a speed syn chronicity between crankshaft 2 and the transmission input shaft 4 is necessary. When he reach this synchronous speed, this crankshaft speed is held for a predetermined period of time t _H. If the selected gear is maintained within this period and the clutch pedal is withdrawn to close the clutch 3 , the automatically performed speed control of the internal combustion engine 1 ends and the signal from the actuating angle sensor 19 on the accelerator pedal 18 is used again for further control of the power actuator 13 on the internal combustion engine.

In the event that during this holding time t _H the gear selector lever 12 is placed in the idle position or returned to the old gear, the control unit 11 controls the speed of this motor by influencing the power actuator 13 of the internal combustion engine 1 by the driving speed (transmission input shaft speed) ) and the Fahrpe dalstellung signaled level, then to influence the internal combustion engine in conventional mode by the signal from the sensor 19 via accelerator pedal deflection.

To explain these relationships, FIGS. 2 and 3 and 4 and 5 allow a comparison of the courses of the engine speed and the operating state of the Fahrpe dals over time during upshifts or downshifts. In this case, 2 a shift-up is shown in Fig. Procedure as in drive assemblies according to the prior art with a direct mechanical connection between the accelerator pedal and the power actuator of the internal combustion engine, that is without speed control during the shifting process, presents itself. Therein, the curve NM shows the course of the engine speed over time, while the curve F shows the operating state of the accelerator pedal 18 . In this illustration, at the time t 1 at the beginning of the upshift, the driving clutch 3 is opened by depressing the clutch pedal in order to interrupt the frictional connection between the internal combustion engine and the transmission. At the same time, the accelerator pedal is withdrawn in its deflection and the gear change is then carried out mechanically by actuating the gear selector lever 12 . Because of the withdrawn accelerator pedal and the open clutch, the engine speed NM drops quickly until it reaches the synchronous speed NS at time t₂. Depending on the switching experience of the driver operating the motor vehicle, a more or less long time passes (t₂ to t₃) until the driver closes the clutch at time t₃ and deflects the accelerator pedal again. During this period, the engine speed NM drops below the synchronous speed NS, so that the switching process takes place at the expense of a more or less large braking torque and with the associated clutch wear.

As can be seen in FIG. 3, such additional braking torques and friction losses do not occur in an upshift operation controlled according to the invention. Here, too, the switching process begins at time t₄ by actuating the clutch pedal and opening clutch 3 and by withdrawing the accelerator pedal. The subsequent drop in the engine speed NM goes however only up to the synchronous speed NS at the time t₅. When this synchronous speed is reached, the control device 11 takes over the speed control of the internal combustion engine 1 in the manner described above, so that during the time interval t₅-t₆ the engine speed NM is kept at the synchronous speed level.

If during this time interval t _H the switching operation by the driver of the motor vehicle is successfully completed by withdrawing the clutch pedal and closing the clutch 3 , the engine accelerator pedal NM can again be controlled depending on the accelerator pedal position by the subsequent accelerator pedal actuation (curve F).

In the event that by the end of the time interval t _H , i.e. by the time t₆ the clutch 3 has not been closed, or the gear selector lever has been reset to the neutral position, the control unit 11 takes over the further reduction of the engine speed to the level corresponding to the accelerator pedal position ( Curve NM ′). If the gear selector lever was placed in a different gear position, the control unit 11 takes over the regulated adaptation of the engine speed NM to the new associated synchronous speed level.

In Fig. 4, the engine speed curve NM and the course of the accelerator pedal actuation F is shown for a downshift, as is typical in drive arrangements with a direct connection between the accelerator pedal 18 and the power actuator 13 of the internal combustion engine 1 . Here, to initiate a downshift at time t₇, the downshift is initiated by actuating the clutch pedal and opening clutch 3 and by withdrawing the accelerator pedal deflection. In the event that the driver gives no intermediate gas for the downshift in the period t₇ to t₁₁, the engine speed NM initially drops until the new gear is mechanically engaged and the clutch 3 is closed at the time t₉. From the beginning of the clutch closing, the clutch tears the speed of the internal combustion engine up to the synchronous speed level NS, which is reached at the time t 1 and from which the accelerator pedal deflection then leads, if appropriate, to a further increase in the engine speed. Such Schaltverhal th means, however, that the engine speed has to be adjusted to the synchro speed by grinding the clutch, which in turn exerts a strong braking force on the driver and adversely affects clutch wear.

In the event that the driver is in the time interval t₇ to t₁₁ intermediate gas (dashed curve NM ') the speed synchronism can be achieved at the time t₁₁. The Einkuppelvor but must be done within a very short period of time, which is usually only very experienced drivers succeed.  

In Fig. 5, however, the speed curve is shown NH of the engine, as it results from the application of the control method according to the invention. Here too, the clutch 3 is opened at a time t 1 by actuating the clutch pedal and the accelerator pedal is withdrawn in its position. If the driver accelerates after initiating the downshift or if he leaves the accelerator pedal in its position, this is ignored by the control unit 11 and the engine speed for a period t _{H is} brought to the synchronous speed of the new target gear by the control unit 11 regardless of the accelerator pedal position kept there. If the driver engages in this phase, optimum shifting comfort is achieved. A further accelerator pedal deflection F 'carried out in this period, for example in the interval t 1 to t 1 , is not passed on to the power actuator 13 of the internal combustion engine 1 .

From the foregoing, it is clear that the inventive Procedure the requirements for the driver regarding the coordination of the accelerator pedal tion and clutch actuation during a shift of a mechanical gearbox bes greatly reduced and driving comfort can be increased significantly. In addition, the thermal The load on the clutch is significantly reduced, which contributes to increasing its service life.

Claims (2)

1. Method for speed control of an internal combustion engine that can be connected via a clutch to a manual transmission, preferably for a motor vehicle, a control device being provided for speed control.
which uses a sensor to determine the deflection of the accelerator pedal,
which emits a control signal to a power actuator on the internal combustion engine,
which receives information about the currently selected or engaged gear from a gear sensor,
which receives information about the actuation state of the clutch from a clutch sensor, and
which the speed of the internal combustion engine and the transmission input shaft is made available by speed sensors, in which the speed of the internal combustion engine automatically when the clutch is triggered by gearshift operations and neglecting the accelerator pedal position signaled by the driver as a function of the selected or engaged gear and is brought from the driving speed of the vehicle to the respective synchronous speed, characterized in that
that the speed of the internal combustion engine after reaching the synchronous speed a predetermined period of time is kept at this synchronous speed, that when the clutch is closed again within this period, the internal combustion engine again follows the speed or power signal signaled by the accelerator pedal and
that when the clutch is not closed after this time or the gear lever is in the idle position, the speed of the internal combustion engine is reduced to the speed level signaled by the accelerator pedal. 2. The method according to claim 1, characterized in that the time period preferred is 200 to 500 milliseconds.