Drive control system for an electrically powered motor vehicle with a gear selector

Abstract

Drive control system for an electrically powered motor vehicle with a gear selector (1) and with an electronic control unit (2, 4) which is connected to the gear selector (1) and is designed such that when a first alternative automatic gear (i) is selected, a non-freely selectable recuperation level can be specified and creeping is deactivated, and that when a second alternative automatic gear (D) is selected, an adjustable fixed recuperation level and creeping are activated.

Description

[0001] The invention relates to a drive control system for an electrically powered motor vehicle with a gear selector and an electronic accelerator pedal.

[0002] The so-called "one-pedal driving" with an electronic accelerator pedal in electric vehicles, a particular characteristic of the BMW i3, provides strong, instantly controllable deceleration almost to a standstill when the accelerator pedal is released. Nissan has also announced an e-Pedal similar to the BMW i3's in the "Nissan Leaf" (electrive.net, July 20, 2017).

[0003] Various recuperation methods for braking electric vehicles are known, for example, from DE 10 2010 004 846 A1, DE 10 2013 211 716 A1 and DE 10 2005 058 829 A1.

[0004] DE 10 2007 035 424 A1 relates to an operating interface in a vehicle comprising a powertrain with a drive unit, wherein the operating interface is designed in such a way that the driver can assume a driving condition as frequently and conveniently as possible in which the drive unit does not transmit any power to the wheels and thus neither propels nor brakes the vehicle.

[0005] WO 2015 / 067867 A2 concerns a strategy for controlling a creep function of a hybrid vehicle with a braking mode with energy recovery, which is automatically activated when the driver releases the accelerator pedal.

[0006] DE 10 2012 223 866 A1 relates to a device for a motor vehicle with an electric drive system, which is designed to prevent the vehicle from rolling on a surface inclined against the direction of travel in a gear position.

[0007] The invention is based on the objective of further improving the adjustment of recuperation behavior in electric drives.

[0008] According to the invention, this problem is solved by the features of claim 1. Preferred embodiments of the invention are specified in the dependent claims.

[0009] The invention relates to a drive control system for an electrically powered motor vehicle with a gear selector and with an electronic control unit which is connected to the gear selector and is designed such that when a first alternative automatic gear is selected, a comparatively high, non-freely selectable recuperation level (preferably the maximum possible recuperation level) can be specified and creeping is deactivated, and that when a second alternative automatic gear is selected, at least one fixed recuperation level or a coasting mode can be specified and creeping is activated.

[0010] In a further development of the invention, when selecting the first alternative automatic driving stage, at least a comparatively high recuperation level and when selecting the second alternative automatic driving stage, at least a comparatively low recuperation level can be selected such that the recuperation level in the second alternative automatic function is always equal to or lower than the recuperation level in the first alternative automatic function.

[0011] The gear selector for selecting the first alternative automatic gear stage or the second alternative automatic gear stage is preferably a selector lever which has a self-resetting toggle switch or a manually reversible changeover switch for this purpose.

[0012] When the first alternative automatic drive mode is selected, the vehicle is preferably always prevented from rolling away from a standstill, even without the accelerator and brake pedals being pressed. If a switchable (i.e., manually activatable and deactivatable) automatic hold function ("Auto-H") is present, the hold function's state is ignored when the vehicle transitions from driving to a standstill. In other words, the vehicle is prevented from rolling away from a standstill whether the hold function is activated or deactivated.

[0013] When the second alternative automatic drive mode is selected, the vehicle is always prevented from rolling backwards when stationary, even without the accelerator and brake pedals being pressed, while forward movement is permitted. If the aforementioned switchable hold function (Auto-H) is present, the vehicle is always prevented from rolling backwards when stationary (i.e., both when the hold function is activated and deactivated), even without the accelerator and brake pedals being pressed. However, forward movement is only permitted when the hold function (Auto-H) is deactivated.

[0014] The invention is based on the following considerations: Thrust recuperation for energy recovery can be permanently or situationally adjustable in several stages.

[0015] In vehicles with combustion engines, there is also a deceleration when the accelerator pedal is released, but it is noticeably less than in the electric vehicles mentioned above. At low speeds, this deceleration transitions into a so-called creep speed, which allows driving at walking pace without using the accelerator pedal. Creeping is particularly helpful when maneuvering and parking. To prevent rolling, for example in stop-and-go traffic or on inclines, BMW's Auto-Hold function is available. This function is similar to an automatic hold function ("Auto-H") that can be activated via a control element when the vehicle transitions from driving to a standstill.

[0016] The one-pedal driving experience takes some getting used to. The urge to continue using the brake pedal is common. Furthermore, while advantageous in the city, it can be tiring on long highway journeys to keep the accelerator pedal pressed to prevent heavy deceleration.

[0017] The aim of this invention is to combine the advantages of the driving styles of a vehicle with an internal combustion engine and an electric vehicle with one-pedal feeling (such as the BMW i3) by introducing a new additional driving mode, called "i", which can be selected as an alternative to the usual driving mode "D" in automatic transmission vehicles, and to allow the customer to decide which driving style should currently be used.

[0018] In this new driving mode ("I"), creep mode is essentially always deactivated, and the recuperation level is high, preferably maximum, and not freely selectable. Unintentional rolling of the vehicle when stationary is prevented by a constantly active, secure holding function. The Auto HOLD button is retained for driving mode D to manually disable creep mode if necessary. For the recuperation settings in driving mode "D," the recuperation level, possibly including SRA (coasting recuperation assistant), can preferably be configured by the driver via a display control unit (e.g., BMW's iDrive). The driver can, for example, choose between SRA or a preferred, multi-stage adjustable recuperation level (e.g., high / medium / low). With SRA (e.g., using camera, radar, and navigation data), the vehicle automatically selects the correct deceleration based on the traffic situation.

[0019] The term alternative automatic driving mode encompasses both a driving mode with a self-shifting transmission and one with a fixed transmission ratio.

[0020] The invention offers the following advantages: - Customer added value - Combination of several drive characteristics in electric drive - The driver can switch between the two drive modes depending on the situation. - The recuperation level can be flexibly adjusted. - Easy to use - Always holds securely in driving mode "I" without applying the brakes

[0021] Exemplary embodiments of the invention are illustrated in the drawing and are described in more detail below. It shows Fig. 1. A schematic overview of the essential components of the drive system according to the invention, including the selection of the first driving stage. Fig. 2 in schematic representation an overview of the essential components of the drive system according to the invention with selection of the second driving stage and optionally configurable recuperation level, Fig. 3 in schematic representation an overview of the essential components of the drive system according to the invention with selection of the second driving stage and optional SRA, Fig. 4. A state diagram for possible changes of the speed-dependent functions starting from standstill.

[0022] In the Fig. Figures 1 to 3 show a drive control system for an electrically operated motor vehicle with an electronic control unit 2, which is connected to a gear selector in the form of a gear selector lever 1, to a display control unit 3 and to an auto-hold button 5 for activating and deactivating the above-mentioned hold function (Auto-H).

[0023] The electronic control unit 2 is designed, in particular by a correspondingly programmed software module 4, such that, in principle, when selecting a first alternative automatic driving stage “i”, a comparatively high (preferably maximum) recuperation level is set and creeping is deactivated when the accelerator pedal is released ( Fig. 1) and that when selecting a second alternative automatic driving mode “D”, at least one selectable fixed recuperation level or a (especially auto-adaptive) coasting mode can be specified and creeping is activated when releasing the accelerator pedal ( Fig. 2 or Fig. 3) Preferably, in the second alternative automatic driving stage “D”, only a recuperation level can be selected that is equal to or less than the recuperation level specified in the first alternative automatic driving stage “i”.

[0024] More precisely, depending on the signals from the gear selector (here in the form of a gear selector lever 1) according to a predefined switching scheme, here: RN-“D” or alternatively “i”, the display control unit 3 and / or the auto-hold button 5, the software module 4 in the control unit 2 preferably performs the following functions: When selecting the first driving mode “i” ( Fig. 1):

[0025] Creeping is always deactivated and the recuperation level is greater than or equal to the highest recuperation level in the second driving stage “D”.

[0026] If an Auto-Hold button “Auto-H” is present, the vehicle will always be prevented from rolling away when stationary, regardless of whether this button is pressed or not.

[0027] If the second driving mode “D” is selected as an alternative ( Fig. 2 and Fig. 3): Creeping is always activated and the recuperation level is at most as high as the recuperation level in the first driving stage “i”.

[0028] The Auto-Hold function can be retained. If the Auto-H function is activated, for example via the button, the vehicle will automatically be held against forward and backward roll as usual once it comes to a standstill. Creeping will then be suppressed. If the Auto-H function is deactivated, for example via the button, or if the function is not present at all, the vehicle will automatically be held against backward roll only once it comes to a standstill. Creeping will not be suppressed.

[0029] When a reverse gear "R" is selected, this function works analogously: If the Auto-H function is deactivated, for example via the button, or if the function is not available at all, the vehicle will automatically be held against forward roll only once it comes to a standstill. Creeping is not suppressed.

[0030] For the design of the recuperation in driving mode "D", the recuperation level can preferably be configured by the driver, possibly including SRA (coasting recuperation assistant), for example via a display control unit 3. The driver has, for example, the choice between the coasting recuperation assistant SRA ( Fig. 3) or a preferred, fixed recuperation level (e.g. high / medium / low; Fig. 2) With the SRA (via camera, radar and navigation data), the vehicle automatically selects the correct deceleration depending on the traffic situation.

[0031] The invention therefore relates, in the context of an electric drive, either to a one-pedal feeling (A) or to the driving feel (B) of an internal combustion engine vehicle with automatic transmission and auto-H function: A) 1. Strong delay when releasing the accelerator pedal 2. No creeping, deceleration to a standstill or at least to almost a standstill - No automatic hold-up required, always safely stationary, even without applying the brake pedal B) 1. Minimal delay when releasing the accelerator pedal 2. Creeping, deceleration to creep speed - Auto-H for roll-away prevention when stationary and suppression of creep moment, whereby when Auto-H is deactivated, the vehicle is only prevented from rolling away in the opposite direction of the previous direction of travel.

[0032] In Fig.Figure 4 schematically illustrates functional transitions for preventing unintentional rolling away. Of particular relevance are transitions from intermediate states Z1 to Z3 at standstill (v=0) (standstill management function).

[0033] Intermediate state Z1 is functionally a holding state associated with the second gear "D". Intermediate state Z2 is functionally a holding state associated with neutral "N". Intermediate state Z3 is functionally a holding state associated with reverse "R".

[0034] If a standstill (v=0) is reached in drive mode "i" and the driver then selects drive mode "D" in step 100 without pressing the brake pedal, the vehicle is initially held in an intermediate state Z1 for safety reasons until the accelerator or brake pedal is pressed according to step 101. Creep mode is then activated in drive mode D.

[0035] If the vehicle switches back to driving mode “i” in intermediate state Z1 with subsequent step 102, driving can continue in driving mode “i” by pressing the accelerator pedal.

[0036] If a standstill (v=0) is reached in drive mode "i" and the driver then selects drive mode "N" in step 103, the vehicle is initially held in an intermediate state Z2 for safety reasons until the brake pedal is pressed in accordance with step 104. Afterwards, the vehicle can transition to normal operation corresponding to drive mode "N". (Path 105 is not currently planned.)

[0037] If the brake is briefly applied in intermediate state Z2, free rolling is then permitted.

[0038] If a standstill (v=0) is reached in drive mode "i" and the driver then selects drive mode "R" in step 106 without pressing the brake pedal, the vehicle is initially held in an intermediate state Z3 for safety reasons until the accelerator or brake pedal is pressed according to step 107. Creep mode is then activated in drive mode R.

[0039] If the vehicle switches back to driving mode “i” in intermediate state Z3 with subsequent step 108, driving can continue in driving mode “i” by pressing the accelerator pedal.

[0040] If, in intermediate state Z1, speed step “N” is selected in step 109, the system transitions to intermediate state Z2.

[0041] If, in intermediate state Z2, speed step “D” is selected in step 110, the system transitions to intermediate state Z1.

[0042] If, in intermediate state Z1, driving stage “R” is selected in step 111, the system transitions to intermediate state Z3.

[0043] If, in intermediate state Z3, driving stage “D” is selected in step 112, the system transitions to intermediate state Z1.

[0044] If, in intermediate state Z2, driving stage “R” is selected in step 113, the system transitions to intermediate state Z3.

[0045] If, in intermediate state Z3, driving stage "N" is selected in step 114, the process transitions to intermediate state Z2.

Claims

[1] Drive control system for an electrically powered motor vehicle with a gear selector (1) and with an electronic control unit (2, 4) which is connected to the gear selector (1) and is designed such that when a first alternative automatic gear (i) is selected, a non-selectable recuperation level can be specified and creeping is deactivated, and when a second alternative automatic gear (D) is selected, an adjustable fixed recuperation level and creeping are activated. [2] Drive control system according to claim 1, characterized by , that the gear selector (1) for selecting the first alternative automatic gear (i) or the second alternative automatic gear (D) has a self-resetting toggle switch or a manually reversible changeover switch. [3] Drive control system according to any of the preceding claims, characterized by, that when the first alternative automatic driving mode (i) is selected, the vehicle is always prevented from rolling away when stationary, even without the accelerator and brake pedals being used. [4] Drive control system according to any of the preceding claims, characterized by , that when the second alternative automatic driving mode (D) is selected, the vehicle is always prevented from rolling backwards when stationary, even without the accelerator and brake pedals being used. [5] Drive control system according to any of the preceding claims, characterized by, that when the second alternative automatic driving stage (D) is selected and a control element (5) for a switchable automatic hold function (Auto-H) is present, upon reaching a standstill, regardless of the operation of the control element (5), the vehicle will not roll backwards while stationary, even without the accelerator pedal and the brake pedal being operated, but forward rolling will be permitted if the hold function (Auto-H) is deactivated (off) via the control element (5). [6] Drive control system according to any of the preceding claims, characterized by, that when a reverse gear (R) is selected and a control element (5) for a switchable automatic hold function (Auto-H) is present, when the vehicle comes to a standstill, forward rolling is always prevented even without actuation of the accelerator pedal and the brake pedal, but backward rolling is permitted if the hold function (Auto-H) is deactivated (off) via the control element (5). [7] Drive control system according to any of the preceding claims, characterized by , that a display control unit (3) is provided by which a desired recuperation level (high, medium, low) can be set when selecting the second alternative automatic driving stage (D). [8] Drive control system according to any of the preceding claims, characterized by, that a display control unit (3) is provided by which a desired recuperation level (high, medium, low) can be set, wherein when the first alternative automatic driving stage (i) is selected the recuperation level is at least equal to the recuperation level that can be set at most when the second alternative automatic driving stage (D) is selected. [9] Drive control system according to any of the preceding claims, characterized by , that by appropriate design of the control unit (2, 4) when leaving the first alternative automatic driving stage (i) while the vehicle is stationary (v=0) a standstill management function can be activated to prevent unintentional rolling away, by which further driving is only permitted after actuation of the brake pedal and / or the accelerator pedal. [10] Software function module (3) for the electronic control unit (2) for carrying out the method according to one of the preceding claims.

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