Method for controlling a sailing function for a motor vehicle to optimize an energy management concept

Abstract

Method for controlling a sailing operating mode function of a motor vehicle with an internal combustion engine and a vehicle battery, comprising the steps: a) Recording the instantaneous battery voltage of the vehicle battery, b) Recording the current temperature of the internal combustion engine, c) Switching off the combustion engine according to a predefined sailing operating mode strategy, taking into account the current battery voltage and the current temperature of the combustion engine (S2), as well as taking into account at least one other parameter, d) where a result of a previous test (S4) is used as a further parameter, which contains information about whether an anomaly (S6) was detectable during one or more previous deactivations of the sailing operating mode function, whereby an anomaly is evaluated as a temporal progression of the deactivation of the sailing operating mode function, and whereby an anomaly is always detected when a reaction time, greater than a specified delta time, deviates from a typical reaction time towards larger values.

Description

[0001] The invention relates to a control of a so-called “sailing function” for optimizing an energy management concept for a motor vehicle, as well as a method for the energy management concept.

[0002] To reduce fuel and energy consumption, modern vehicles are equipped with so-called start-stop systems, which shut off the combustion engine when the vehicle is stationary (for example, at a red light). These systems can be used in vehicles powered solely by combustion engines, but also in hybrid vehicles, which have an electric drive motor in addition to a combustion engine.

[0003] In order to reduce fuel consumption and energy consumption even when the vehicle is in motion, or to keep fuel consumption as low as possible, modern vehicles are also equipped with a so-called “sailing operating mode” (in addition to start-stop controls).

[0004] In motor vehicles, the term "coasting" describes the function of decoupled and, if necessary, switched off the combustion engine from the drivetrain while driving. This allows the available kinetic energy to be used for propulsion instead of wasting it in the form of drag.

[0005] In the light of the invention, the term “sailing operation” is to be understood as sailing with the combustion engine switched off and, in a broader sense, also as an automatic engine switch-off of the combustion engine in the sense of an automatic start-stop system, which comes into effect when the vehicle is stationary.

[0006] For example, when approaching and stopping at a traffic light, the coasting mode can be activated during the “coasting process” (even before the vehicle comes to a stop), and in terms of timing, it essentially precedes the automatic start-stop function.

[0007] When coasting mode is terminated or deactivated with engine shutdown, the combustion engine is restarted. Several criteria are used to terminate coasting mode or deactivate the automatic engine shutdown of the combustion engine, such as: a) deactivation of the foot brake when the vehicle is stationary, b) operating the steering when the vehicle is stationary, c) an accelerator pedal operation while driving in order to “request” drive power, d) operating the mode selector lever on an automatic transmission when the vehicle is stationary.

[0008] The coasting mode is activated, for example, when the driver “takes back” the accelerator pedal while driving or stops (e.g. at a traffic light or intersection).

[0009] The different criteria for activating and deactivating the sailing operating mode are usually specified by a sailing operating mode strategy.

[0010] Various operating strategies for a start-stop or sailing function are known, for example, from DE 10 2016 000 721 A1, DE 10 2014 208 758 A1, and DE 10 2009 034 004 A1. Control of a sailing mode, taking into account, among other things, the battery charge level and engine temperature, is described, for example, in DE 10 2014 220 712 A1.

[0011] Deactivating coasting mode is associated with a certain reaction time, which the combustion engine requires to return to the required speed. During this reaction time, the steering assistance (servo-assisted operation) may not yet be available at 100%. This effect can be exacerbated if the starting behavior of the combustion engine deteriorates over time due to vehicle aging, i.e., if the reaction time increases, for example.

[0012] This slight reduction in assistance is not particularly significant for steering, although a reduction in braking power (in the initial phase of a braking maneuver) of just a few percent can be crucial in avoiding a rear-end collision with the vehicle ahead in the event of a sudden hazard. Likewise, and especially when driving during acceleration—starting from coasting—excessively long reaction times should always be considered critical, as this prolongs the overtaking maneuver and places longer demands on the overtaking lane / oncoming lane.

[0013] The object of the invention can be seen in the fact that it is possible to present a solution by means of which it can be ensured that, even in sailing mode, a good braking performance, and in particular a rapid acceleration performance (power demand of the combustion engine) can be ensured, or that a delay in the acceleration performance and a reduction in the braking performance in sailing mode is avoided, a) e.g. in a situation where the vehicle is operating in coasting mode and emergency braking is necessary due to a driving error caused by a third party, or b) e.g. in a situation where the vehicle is operating in coasting mode and the driver spontaneously wishes to overtake.

[0014] The problem is solved by a method, a control device, and a motor vehicle according to the independent claims. Advantageous further developments are specified in the dependent claims.

[0015] The method according to the invention for controlling a sailing operating mode function of a motor vehicle with an internal combustion engine and a vehicle battery comprises the steps: a) Detecting the current battery voltage of the vehicle battery, b) Recording the current temperature of the combustion engine, c) Switching off the combustion engine according to a predefined sailing mode strategy, taking into account the current battery voltage and the current temperature of the combustion engine and at least one other parameter, d) where a result of a previous test is used as an additional parameter.

[0016] A motor vehicle for implementing the method according to the invention can have a conventional drive with an internal combustion engine or a hybrid drive that additionally has an electric drive motor. The battery voltage of a vehicle battery is a measure of the vehicle battery's state of charge. The vehicle battery can preferably be charged by the internal combustion engine and serves as an energy storage device, for example, for operating the electric drive motor in a hybrid drive or for (re)starting the internal combustion engine.

[0017] The sailing operating mode strategy of a vehicle with an internal combustion engine, for example, provides that the internal combustion engine (when the vehicle is stopped and) in particular when there is a NON-required power demand or power output from the internal combustion engine to the drive train, for example a) when the vehicle speed is reduced, and / or b) is switched off during a journey in which the vehicle is driving on a downhill road.

[0018] Activating a coasting mode with engine shutdown is usually followed by deactivating a coasting mode (switching on or starting the engine). Therefore, when activating the coasting mode, it is preferable to check relevant parameters before shutting down the engine to ensure that the engine can be restarted safely afterwards.

[0019] Therefore, the input parameters for deciding whether to switch off the combustion engine are a) in accordance with the state of the art, in particular the battery voltage of a vehicle battery and the temperature of the combustion engine are taken into account, and b) according to the invention at least one further input parameter is taken into account, wherein a result of a previous test is used as a further parameter.

[0020] In the present solution according to the invention, it is assumed as a premise that the input parameters according to the prior art, in particular a) the battery voltage of a vehicle battery and b) the temperature of the combustion engine, would each be evaluated as POSITIVE, or a sailing operating mode would be enabled on the basis of these parameters, unless the at least one further input parameter according to the invention would be taken into account.

[0021] According to the invention, it is proposed that at least one further parameter is taken into account as an influencing variable as to whether or not the combustion engine is switched off by means of the sailing operating mode function when the vehicle is moving, wherein a result of a previous test is used as a further parameter.

[0022] A previous test here preferably refers to an evaluation of one or more previous functions of the motor vehicle. Such a function can in particular be an activation or deactivation of the sailing operating mode function. For this purpose, for example, one or more parameters characteristic of the execution of the function are recorded and evaluated by a control device of the motor vehicle. A characteristic parameter can, for example, be the temporal progression during the execution of the function. According to the invention, the reaction time during the deactivation of a sailing operating mode function of the motor vehicle is recorded and evaluated as the temporal progression. The reaction time here is, for example, the time that elapses between a decision to start the combustion engine until it reaches the required speed.

[0023] At this point, it should be noted that, in the light of the invention, the wording “result of a previous test” does not have to be limited to a single test, but that the result can also be based on a sequence of tests or several tests.

[0024] According to the invention, the result of the previous test includes information about whether an anomaly was detected during one or more previous deactivations of the sailing operating mode function.

[0025] The solution according to the invention is further characterized by the fact that the deactivation of the sailing operating mode function is evaluated over time. An anomaly can then be detected, for example, if a deviation, in particular a delay, occurs during the deactivation of the sailing operating mode function, which differs from proper operation.

[0026] In other words: In the light of the invention, the phrase “time course of the deactivation of the sailing operating mode function” is to be understood as meaning that the temporal starting behavior of the internal combustion engine is monitored or evaluated by means of testing technology, or whether any abnormalities can be detected in the temporal starting behavior of the internal combustion engine, in particular in the sense that the internal combustion engine has “poor” starting behavior.

[0027] An anomaly may, for example, be that the reaction time of the combustion engine is increased compared to a typical reaction time for a new vehicle of the same vehicle type.

[0028] According to the invention, an anomaly is detected if the deviation of the reaction time from a typical reaction time upon deactivation of the coasting operating mode is greater than a predetermined delta time, in particular towards larger values. A typical reaction time preferably refers to a new vehicle of the same vehicle type. An anomaly is always detected, for example, if a currently determined actual reaction time is twice as long as the typical reaction time for a new vehicle of the same type.

[0029] In the light of the invention, the term “reaction time” is to be understood as meaning in particular a time which is required by the vehicle technology, a) starting from the decision to deactivate the sailing mode, b) until the time required for the internal combustion engine to be started or for power to be demanded from the internal combustion engine. Power can generally be demanded when the internal combustion engine has reached the required speed.

[0030] In a further advantageous embodiment of the invention, the solution according to the invention is characterized in that the anomalies are evaluated by means of a qualification counter in order to obtain a result.

[0031] In a further advantageous embodiment of the invention, the solution according to the invention is characterized in that the qualification counter counts both incrementally and decrementally, wherein the qualification counter can be limited by limits when counting, for example the initial value at ZERO and the maximum count value significantly above the predetermined value, which serves as a limit for the result formation (the limit or the value of the limit for the result formation is preferably in a range, for example, between greater than 1 and less than 5).

[0032] In a further advantageous embodiment of the invention, the result formation depends on a predetermined value of the qualification counter in that the predetermined value of the qualification counter is exceeded.

[0033] In a further advantageous embodiment of the invention, activation of the sailing operating mode is NOT enabled if the qualification counter has exceeded a predetermined value during result formation.

[0034] In a further advantageous embodiment of the invention, activation of the sailing operating mode is only NOT enabled if the vehicle is NOT at a standstill.

[0035] In a further advantageous embodiment of the invention, the solution according to the invention is characterized in that a) when an anomaly is detected, the current value of the qualification counter is incremented by 2, and b) if an anomaly is NOT detected, the current value of the qualification counter is decremented by 1.

[0036] Furthermore, the invention comprises a control device with a processor unit which is configured to carry out a method according to the invention for controlling a sailing operating mode function.

[0037] Furthermore, the invention comprises a motor vehicle with a corresponding control device including a sailing operating mode function according to the invention.

[0038] The advantage resulting from the invention is particularly that a) in addition to the parameters according to the state of the art, for activating the sailing mode / deactivating the combustion engine, b) additionally, past anomalies regarding the deactivation of the sailing mode / activation of the combustion engine are taken into account, c) and then, if there are any abnormalities, the activation of the sailing operation is omitted or deactivated / prevented, so that d) in the event of potential problems when deactivating the sailing mode / activating the combustion engine, no critical situations can arise during driving, and e) so that, in particular when accelerating the vehicle, there are no unwanted delays (until the combustion engine reaches the required speed again in order to be able to deliver the required power), and / or f) at the start of a possible emergency braking manoeuvre initiated by the driver (or by an environmental monitoring assistance function), continuous 100% braking functionality is guaranteed.

[0039] In a further advantageous embodiment of the invention, the solution according to the invention is characterized in that this above-mentioned additional abnormality-oriented control parameter is also very advantageous in autonomous driving operation or in an autonomous driving mode, since due to the acting combustion engine control, “valuable time” can be gained compared to a reacting combustion engine control, or the required engine power can always be called up (without time delay / delta time) when it is needed.

[0040] In the following, the invention will be described with reference to Fig. 1 will be explained in more detail using examples.

[0041] They show schematically: Fig. 1: a flowchart for carrying out the method according to the invention according to an embodiment variant.

[0042] Fig.1 shows an example of the implementation of the method according to the invention according to a preferred embodiment.

[0043] In step S1, the method begins by starting or driving the vehicle. In step S2, a check is carried out to determine whether coasting mode is still possible (according to state-of-the-art criteria, particularly the input parameters battery voltage and engine temperature).

[0044] In step S3, it is checked whether a sailing operating mode is / would be possible based on a current driving scenario (e.g. due to a reduction in vehicle speed, coasting of the vehicle, no power demand due to the vehicle driving downhill).

[0045] Depending on the result of step 3, if sailing mode is no longer possible, no sailing mode will be activated in step 5, or if necessary, sailing mode will be deactivated. When deactivating sailing mode, a check will be carried out again for abnormalities (e.g. a certain time delay due to aging effects) in order to decrement or increment a qualification counter if necessary.

[0046] If, however, the result of step 3 is that a sailing operating mode is / would be possible due to the current driving scenario, step 4 checks whether the deactivation of the sailing mode (restart of the combustion engine) was conspicuous in the past, or whether there were any conspicuous occurrences, or whether a corresponding qualification counter has already exceeded a specified value?

[0047] Depending on the result of step 4, step 6 will proceed accordingly.

[0048] If there were no abnormalities, the sailing mode is released in step 8.

[0049] However, if there were any anomalies, further checks will be carried out in step 7, - whether the sailing operation is carried out while the vehicle is moving, or - whether sailing should take place when the vehicle is stationary.

[0050] Depending on the result of step 7, the process continues in step 9.

[0051] If the sailing operating mode is to be activated when the vehicle is stationary, the sailing operating mode is enabled in step 10.

[0052] However, if the sailing mode is to be activated when the vehicle is moving, the sailing mode is NOT enabled in step 11.

[0053] The advantage associated with step 10 is, among other things, that it allows for repeated checks to determine whether an anomaly (still) exists, and a corresponding counter can be incremented or decremented to qualify the anomaly. This is easier (in the sense of less critical) with a stationary vehicle, since an irregularity during the vehicle's approach is less critical than during an intentional acceleration maneuver when overtaking, since in the latter case, any time delay (excessive reaction time) significantly increases the risk of an accident.

Claims

[1] Method for controlling a sailing operating mode function of a motor vehicle with an internal combustion engine and a vehicle battery, comprising the steps: a) Detecting the current battery voltage of the vehicle battery, b) Recording the current temperature of the combustion engine, c) switching off the combustion engine according to a predefined sailing mode strategy, taking into account the current battery voltage and the current temperature of the combustion engine (S2) as well as at least one other parameter, d) where a result of a previous test (S4) is used as an additional parameter, which contains information about whether an anomaly (S6) was detectable during one or more previous deactivations of the sailing operating mode function, wherein a temporal course of the deactivation of the sailing operating mode function is evaluated as an anomaly, and wherein an anomaly is always detected when a reaction time, greater than a predetermined delta time, deviates from a typical reaction time towards larger values. [2] Method for controlling a sailing operating mode function according to claim 1, wherein the anomalies are evaluated by means of a qualification counter (S5) in order to obtain a result. [3] A method for controlling a sailing mode function according to claim 2, wherein the qualification counter (S5) counts both incrementally and decrementally. [4] Method for controlling a sailing operating mode function according to one of claims 2 to 3, wherein the result formation is dependent on a predetermined value of the qualification counter in that the predetermined value of the qualification counter is exceeded. [5] Method for controlling a sailing operating mode function according to one of claims 2 to 4, wherein activation of the sailing operating mode is not enabled if the qualification counter has exceeded a predetermined value during the result formation. [6] Method for controlling a sailing operating mode function according to claim 5, wherein activation of the sailing operating mode is not enabled (S7 S9) only when the vehicle is not at a standstill. [7] Method for controlling a sailing mode function according to one of claims 2 to 5, a) where, upon detection of an anomaly, the current value of the qualification counter (S5) is incremented by the value 2, and b) if an anomaly is NOT detected, the current value of the qualification counter (S5) is decremented by the value 1. [8] Control device with a processor unit which is arranged to carry out a method for controlling a sailing operating mode function according to one of the preceding claims. [9] Motor vehicle with a control device according to claim 8.

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