Method for controlling an automatic shutdown process of an internal combustion engine

Abstract

Method for controlling an automatic shutdown process of an internal combustion engine in a motor vehicle, wherein the internal combustion engine is automatically switched off when all predetermined shutdown conditions are met, characterized in that an automatic shutdown of the internal combustion engine (BKM) is prevented when a child seat is detected in the motor vehicle (20).

Description

[0001] The invention relates to a method for controlling an automatic shutdown process of an internal combustion engine in a motor vehicle according to the preamble of claim 1.

[0002] To reduce fuel consumption and pollutant emissions, processes and systems are currently being developed, and some are already in use, that automatically shut down a motor vehicle's internal combustion engine under certain conditions or when predefined shutdown conditions are met, and automatically restart it when predefined startup conditions are met. Such processes and systems, or start-stop devices, are particularly suitable for reducing fuel consumption in urban traffic, since in urban traffic the vehicle often comes to a stop at traffic lights or due to traffic, and the operation of the internal combustion engine is not required.

[0003] For example, DE 101 61 343 A1 discloses an automatic stop and start control device for an internal combustion engine. The control device takes appropriate measures to shut down the internal combustion engine if all of the aforementioned shutdown conditions are met. For example, the vehicle speed must be below a specified limit, and in manual transmissions, no gear may be engaged.

[0004] Under certain circumstances, however, it may happen that the driver desires an automatic shutdown of the internal combustion engine and performs all necessary actions, but this is not possible due to a lack of system-related prerequisites. For example, DE 100 30 290 A1 discloses a method and a system for automatically shutting down and restarting an internal combustion engine, in which automatic shutdown is prevented if the vehicle's battery charge level is below a predetermined threshold.

[0005] Furthermore, DE 10 2007 009 871 A1 discloses a method for controlling an automatic shutdown process of an internal combustion engine, wherein an automatic shutdown is prevented, however, if the vehicle has previously been towed.

[0006] For further information on the state of the art, please refer to DE 10 2009 029 365 A1 and DE 20 2009 009 464 U1.

[0007] The object of the invention is to provide an improved method for controlling an automatic shutdown process of an internal combustion engine, by means of which an automatic shutdown of the internal combustion engine is prevented if it can be assumed with a high degree of probability that the driver, despite initiating all necessary measures, probably still does not want a shutdown and would rather find it disturbing.

[0008] This object is achieved by a method according to claim 1. Advantageous further developments emerge from the dependent claims. The method according to the invention, as well as its advantageous embodiments, can be implemented by means of an implemented algorithm or a corresponding assembly arrangement in at least one control device provided for this purpose, in particular in an engine control device.

[0009] The invention is based on the finding that the steady vibration of the vehicle and the noise of the engine during operation have a calming effect on small children. This "steady" noise level and vibration should be maintained, especially when small children are sleeping, since the elimination of vibration and engine noise, as well as sudden jolts or shaking when the engine is turned off or restarted, would wake many children from sleep.

[0010] In order to prevent this problem from occurring, the invention provides that an automatic shutdown of the internal combustion engine is prevented if a child seat is detected in the motor vehicle, ie when a child seat is detected in the vehicle, a shutdown prevention function is activated so that an automatic shutdown of the internal combustion engine is prevented despite the presence of all (other) shutdown conditions.

[0011] Advantageously, automatic shutdown of the engine can only be prevented if an occupied child seat is detected. This is particularly useful for child seat systems that are permanently installed in the vehicle.

[0012] Advantageously, the automatic shutdown of the internal combustion engine can be prevented by deactivating a function that automatically shuts off the internal combustion engine, which can be part of a so-called "automatic start-stop system" or a "hybrid control unit," as soon as it is detected that a child seat, in particular an occupied child seat, is present in the vehicle. Deactivation offers the advantage that, even due to a malfunction, e.g., due to faulty signal evaluation, automatic shutdown of the internal combustion engine cannot occur for the duration of the deactivation. Furthermore, deactivation of the entire system leads to a reduction in system load (processor and memory utilization). Advantageously, automatic deactivation remains active for the entire duration of the driving cycle.The automatic deactivation can only be canceled when the current driving cycle is ended (manually switching off the engine and / or switching off the ignition).

[0013] Alternatively, instead of deactivating the automatic start-stop system, the engine can be prevented from automatically shutting down when a child seat is detected by using a simple driver shutdown prevention device. In this case, the system that influences the automatic shutdown and starting of the engine (automatic start-stop system) is always active, and the stopping capability is continuously checked until a standstill is reached. If a child seat is detected, the stopping capability is denied, and the engine is not automatically shut down.

[0014] Advantageously, a child seat, in particular an occupied child seat, is recognized by detecting and evaluating a signal from a child seat or child seat occupancy detection unit.

[0015] For example, if the motor vehicle is equipped with an input system for manually entering or noting that a child seat or an occupied child seat is present in the vehicle, the presence or absence of this child seat notation can be used to determine whether a child seat or an occupied child seat is present, and the automatic shutdown of the engine can be prevented or enabled accordingly. With this type of child seat detection, the control logic for automatically shutting down the engine relies on the driver or another vehicle occupant making a correct notation.

[0016] Additionally or alternatively, however, automatic child seat detection or automatic detection of an occupied child seat can also be implemented. For example, a child seat or an occupied child seat can be detected using an (already present) interior monitoring device. An interior monitoring unit can be a camera system that detects a child seat or an occupied child seat through appropriate (image) signal analysis.

[0017] Alternatively or additionally, a child seat, especially an occupied child seat, can also be detected using a simple seat occupancy detection device (which is already present). For example, a pressure measuring mat integrated into the seat can be used to determine whether a child seat is occupied or not, based on the pressure and the arrangement of the pressure points.

[0018] In a particularly advantageous embodiment of the invention, a child seat can also be detected by means of a suitable evaluation unit on the ISOFIX system. For example, a contact switch can be arranged on at least one ISOFIX mount, which changes its switching state when a child seat is connected. By appropriately evaluating the switching state, a child seat connected to the ISOFIX system can thus be easily detected and the automatic start / stop control of the internal combustion engine can be influenced accordingly.

[0019] The method according to the invention will now be explained in more detail using an exemplary embodiment. The single FIGURE shows a simplified flowchart for deactivating a function that automatically shuts down the internal combustion engine as soon as a child seat configured as an infant carrier is detected in the vehicle.

[0020] It is assumed that the motor vehicle configured to execute the flowchart is equipped with a so-called "automatic engine start-stop function" (AFFS) for automatically stopping and restarting the internal combustion engine (BKM). In addition, the motor vehicle is equipped with a drive system that includes at least one internal combustion engine (BKM) for powering the motor vehicle. The algorithm depicted in the flowchart can be implemented in a dedicated control unit, e.g., in the engine control unit.

[0021] The flow chart for the method according to the invention begins in step 0 as soon as it is detected that the internal combustion engine BKM is in operation and the automatic engine start-stop function ASSF is not switched off, i.e. is switched on.

[0022] If this is the case, the next step 10 continuously checks when all the basic requirements for initiating an automatic shutdown process of the internal combustion engine (BKM) are met. As an example, it is shown here that the vehicle must be stationary, i.e., the vehicle's speed v must be at least almost zero. Additionally, all other shutdown conditions that must also be met can be queried here—even if not shown.

[0023] If it is detected in step 10 that automatic shutdown of the internal combustion engine is fundamentally possible, the next step 20 queries whether a so-called shutdown inhibitor is active, which prevents automatic shutdown of the internal combustion engine BKM. As a concrete example, step 20 shows a check for the presence of a child seat in the vehicle. This means that it checks whether a child seat is present in the vehicle and therefore whether automatic shutdown of the internal combustion engine BKM must be prevented. In this example, a child seat can be detected in two different ways.

[0024] Firstly, a child seat is detected if it has been manually entered by the driver or another person. Alternatively, a child seat can also be detected by evaluating the switch position of all contact switches arranged on the ISOFIX mounts and designed to detect a child seat attached to the mount. If it is detected that at least one switch is closed, i.e., the S_ISOFIX condition is met, it can also be concluded that a child seat is connected.

[0025] If one of the two conditions is met, the system proceeds from step 20 to step 60, and the ASSF function for automatically stopping and restarting the drive unit is deactivated by generating a deactivation signal ASSF_off. Subsequently, in the next step 70, the system waits until the BKM internal combustion engine is manually switched off. If manual switching off of the BKM internal combustion engine is detected, the ASSF function for automatically stopping and restarting the BKM drive unit is reactivated in the next step 80 by generating an activation signal ASSF_on, so that it is available again for the following driving cycle.

[0026] However, if no child seat is detected in step 20, the system proceeds to step 30 and, assuming no other shutdown prevention device is active, the internal combustion engine BKM is shut down. Subsequently, in step 40, the occurrence of a start-up request signal EA is monitored. This could, for example, be a clutch actuation. If a start-up request signal EA is present, the internal combustion engine is automatically restarted in step 50, and the process is terminated.

[0027] The method according to the invention can be used to improve the functioning of a so-called automatic start-stop system in a simple and cost-effective manner and thus increase driver acceptance.

Claims

[1] Method for controlling an automatic shutdown process of an internal combustion engine in a motor vehicle, wherein the internal combustion engine is automatically switched off when all predetermined shutdown conditions are met, characterized by that an automatic shutdown of the internal combustion engine (BKM) is prevented if a child seat is detected in the vehicle (20). [2] Method according to one of the preceding claims, characterized by that an automatic shutdown of the internal combustion engine (BKM) is prevented if an occupied child seat is detected in the vehicle. [3] Method according to claim 1 or 2, characterized by that an automatic shutdown of the internal combustion engine (BKM) is prevented by deactivating a function (ASSF_aus) that automatically switches off the internal combustion engine. [4] Method according to one of the preceding claims, characterized bythat the presence of a child seat, in particular an occupied child seat, in the vehicle can be noted by means of a system that can be operated by the driver (in my opinion), and a child seat, in particular an occupied child seat, is recognized depending on the child seat note (20). [5] Method according to one of the preceding claims, characterized by that a child seat, in particular an occupied child seat, is detected by means of an interior monitoring device. [6] Method according to one of the preceding claims, characterized by that a child seat, in particular an occupied child seat, is detected by means of a seat occupancy detection device. [7] Method according to one of the preceding claims, characterized by that a child seat, especially an occupied child seat, is detected by the evaluation of an IXOFIX system. [8] Method according to one of the preceding claims, characterized bythat the ISOFIX system is equipped with a contact switch on at least one ISOFIX mounting and that a child seat is detected by evaluating the switching state (S_ISFIX) of the contact switch.

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