Vehicle control device
By predicting engine speed and rotational acceleration, setting judgment values to predict excessive rotation and performing torque reduction processing, the problem of excessive engine rotation is solved, and stable engine control is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-11-06
- Publication Date
- 2026-05-22
AI Technical Summary
In existing technologies, stopping fuel supply after the engine reaches its maximum speed is still not an effective way to suppress excessive engine rotation.
By predicting engine speed and rotational acceleration, a judgment value is set to predict excessive rotation, and when excessive rotation is predicted, torque reduction processing is performed, such as fuel cut-off and ignition timing delay, to control engine torque reduction.
It effectively suppresses excessive engine rotation, prevents the engine speed from rising further, and achieves stable engine operation.
Smart Images
Figure CN122071968A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a vehicle control device. Background Technology
[0002] There is a technique that stops the fuel supply when the engine speed reaches a predetermined upper limit speed to suppress excessive engine rotation (e.g., see Patent Document 1).
[0003] Patent Document 1: Japanese Patent Application Publication No. 2011-017255 Summary of the Invention
[0004] Even if fuel injection stops after the engine reaches its maximum speed, the engine speed will not drop immediately, which may not be enough to suppress excessive engine rotation.
[0005] Therefore, the object of the present invention is to provide a vehicle control device that can sufficiently suppress excessive engine rotation.
[0006] The above objective can be achieved by a vehicle control device comprising: a prediction unit that predicts whether the engine is over-rotating based on at least one of a predicted value of the engine speed mounted on the vehicle, i.e., the predicted engine speed and the engine's rotational acceleration; and a control unit that, if the engine is predicted to be over-rotating, performs a torque reduction process that reduces the engine's torque compared to the case where the engine's over-rotation is not predicted.
[0007] The prediction unit predicts that the engine is over-rotating in any of the following situations: the predicted rotational speed is above a first determination value; the rotational acceleration is above a second determination value; and the predicted rotational speed is above the first determination value and the rotational acceleration is above the second determination value.
[0008] The vehicle control device may include a setting unit that sets the first and second determination values to smaller values as the gear position in the transmission located in the power transmission path between the engine and the drive wheels of the vehicle is lower, and sets the first and second determination values to predetermined values when the transmission is in neutral.
[0009] The setting unit can set the first and second determination values to predetermined values when the clutch located on the power transmission path is in the open state.
[0010] The prediction unit can predict whether the engine is over-rotating if at least one of the following conditions is met: it is not a period during which the transmission performs shift control, it is not a period during which combustion of a portion of the engine's cylinders is suspended and combustion is carried out by the remaining cylinders, and the engine speed is not below a predetermined value.
[0011] The prediction unit can calculate the predicted rotational speed based on the current engine speed and the value obtained by multiplying the current rotational acceleration by a predetermined time.
[0012] The specified time can be set to a length greater than or equal to the delay time from the start of the torque reduction process to the start of the engine speed decrease.
[0013] Invention Effects
[0014] According to the present invention, a vehicle control device capable of sufficiently suppressing excessive engine rotation can be provided. Attached Figure Description
[0015] Figure 1 It is a schematic diagram of the vehicle's structure.
[0016] Figure 2 This is a flowchart illustrating over-rotation suppression control.
[0017] Figure 3 This is a timing diagram illustrating over-rotation suppression control.
[0018] Mapping table Figure 4 A is a mapping used to set the first decision value A. Figure 4 B is a mapping used to set the second decision value B. Detailed Implementation
[0019] [General Structure of the Vehicle]
[0020] Figure 1This is a schematic diagram showing the general structure of vehicle 1. Vehicle 1 includes a torque converter (T / C) 12, a clutch 13C, and an automatic transmission (A / T) 14 in the power transmission path between the engine (ENG) 10 and the drive wheels 18. The engine 10 is a gasoline engine with multiple cylinders, but it can also be a diesel engine or a hydrogen engine. The torque converter 12 is connected to the crankshaft 11 of the engine 10. The turbine shaft 13 of the torque converter 12 is connected to the input side of the automatic transmission 14 via the clutch 13C, thereby transmitting the driving force of the engine 10 to the automatic transmission 14. The clutch 13C is engaged when hydraulic pressure is supplied, thereby connecting the power transmission between the turbine shaft 13 and the input shaft of the automatic transmission 14. The clutch 13C is disengaged when the hydraulic pressure supply stops, thereby disconnecting the power transmission between the turbine shaft 13 and the input shaft of the automatic transmission 14. Alternatively, the torque converter 12 may not be included. Furthermore, the automatic transmission 14 may be a gear-type transmission.
[0021] The output shaft 15 of the automatic transmission 14 is connected to a differential 16, which serves as a final reduction gear. Left and right axles 17 are connected to the differential 16. The driving force transmitted to the output shaft 15 is transmitted to the drive wheels 18 via the axles 17.
[0022] The automatic transmission 14 is a stepped transmission, comprising multiple hydraulic friction engagement elements and a planetary gear system. In the automatic transmission 14, by selectively engaging the multiple friction engagement elements, it can be switched to any one of the following gears: P (Park), R (Reverse), N (Neutral), and D (Drive). The automatic transmission 14 has an AT clutch 14C. The AT clutch 14C is engaged when supplied with hydraulic pressure, thereby connecting the power transmission between the input and output shafts of the automatic transmission 14. The AT clutch 14C is disengaged when the hydraulic pressure supply stops, thereby disconnecting the power transmission between the input and output shafts of the automatic transmission 14. When the AT clutch 14C is disengaged, the automatic transmission 14 shifts to the N gear.
[0023] The Electronic Control Unit (ECU) 20 is an electronic control unit that performs control processing related to the vehicle 1. The ECU 20 is a computer that includes a Central Processing Unit (CPU), Random Access Memory (RAM), or Read Only Memory (ROM). The ECU 20 is an example of a vehicle control device, and more specifically, it functionally implements the prediction unit, control unit, and setting unit described later.
[0024] A crankshaft angle sensor 21 and a shift position sensor 22 are connected to the ECU 20. The crankshaft angle sensor 21 detects the engine speed of the engine 10. The shift position sensor 22 detects which of the following positions the shift lever is in: P, R, N, or D.
[0025] The ECU 20 calculates the required torque or target speed for the engine 10 based on the engine speed, intake air volume, and throttle opening detected by the aforementioned sensors. The ECU 20 then controls the fuel injection quantity, intake air volume, and ignition timing based on the required torque or target speed. For example, when the engine 10 is idling, the ECU 20 controls the fuel injection quantity, intake air volume, and ignition timing to ensure that the engine speed reaches the target idle speed and the engine torque becomes the supplied torque. Furthermore, the ECU 20 controls the drive of the clutch 13C or the automatic transmission 14 through the control of the hydraulic control mechanism.
[0026] As explained below, ECU 20 performs over-rotation suppression control to suppress excessive rotation of engine 10 when specified conditions are met. Furthermore, ECU 20 calculates the rotational acceleration of engine 10 based on the engine speed. The rotational acceleration of engine 10 is used for over-rotation suppression control.
[0027] [Over-rotation suppression control]
[0028] Figure 2 This is a flowchart illustrating the over-spinning suppression control. This control is continuously repeated during ignition on-time. ECU 20 determines whether the prediction preconditions used to predict whether engine 10 is over-spinning are met (step S1). If "No" is met in step S1, this control ends. Details regarding the prediction preconditions will be described later.
[0029] If "Yes" is selected in step S1, ECU20 sets the first determination value A and the second determination value B (step S2). Details regarding the first determination value A and the second determination value B will be described later. Step S2 is an example of a process performed by the setting unit.
[0030] In step S3, ECU 20 predicts whether engine 10 is over-rotating (step S3). Whether engine 10 is over-rotating is determined based on the predicted engine speed (a predicted value of engine speed) and the rotational acceleration of engine 10. The predicted engine speed refers to the predicted value of engine speed after a predetermined time (e.g., several tens to several hundred ms) from the current time. The predicted engine speed is calculated, for example, as follows.
[0031] Predicted engine speed [rpm] = Detected current engine speed [rpm] + Engine speed acceleration [rpm / sec] × Specified time [sec] × Gain
[0032] The specified time is set based on the delay time from the issuance of the execution instruction for torque reduction processing (described later) until the actual reduction of engine torque 10 begins. Gain is a tuning element.
[0033] For example, when the crankshaft angle sensor 21 is sampled by the ECU 20 every 0.002 seconds, the rotational acceleration of the engine 10 is calculated as follows.
[0034] Rotational acceleration [rpm / sec] = {rotational speed (n) - rotational speed (n-1)} / 0.002
[0035] The rotational speed (n) is the latest value of the engine speed of the engine 10 obtained by the ECU 20, and the rotational speed (n-1) is the previous value of the engine speed of the engine 10 obtained by the ECU 20. Furthermore, the rotational acceleration of the engine 10 can be calculated, for example, as follows.
[0036] Rotational acceleration [rpm / sec] = {rotational speed (n) - rotational speed (n-3)} / 0.006
[0037] The rotational speed (n-3) is the first four values of the rotational speed of engine 10 obtained by ECU20.
[0038] If the predicted rotational speed is greater than or equal to the first determination value A and the rotational acceleration is greater than or equal to the second determination value B, the determination in step S3 is "Yes". If the predicted rotational speed is less than the first determination value A or the rotational acceleration is less than the second determination value B, the determination in step S3 is "No". If the determination in step S3 is "No", the control ends. Step S3 is an example of the processing performed by the prediction unit.
[0039] If "yes" is indicated in step S3, the ECU 20 performs a torque reduction process (step S4) that reduces the torque of the engine 10 compared to the case where "no" is indicated in step S3. For example, the torque reduction process is achieved by cutting off fuel, delaying ignition timing, cutting off fuel in a portion of the cylinders of the engine 10, and delaying the ignition timing of the remaining cylinders. This suppresses excessive rotation of the engine 10. Step S4 is an example of a process performed by the control unit.
[0040] Figure 3 This is a timing diagram illustrating over-rotation suppression control. Figure 3 The changes in actual speed, predicted speed, rotational acceleration, and actual torque of engine 10 are shown when the throttle opening is constant. Furthermore, in... Figure 3In addition to the values described above in this embodiment, which predict the over-rotation of engine 10 based on predicted rotational speed and rotational acceleration, a comparative example in which over-rotation is determined solely based on actual rotational speed and actual torque is also shown.
[0041] First, a comparative example will be explained. When the actual rotational speed of engine 10 reaches or exceeds the first determination value A (time t4), a torque reduction process is performed to decrease the actual torque of engine 10 (time t5). However, there is a delay between the rotational speed reaching or exceeding the first determination value A and the actual reduction in the actual torque of engine 10. Therefore, after time t4, the rotational speed significantly exceeds the first determination value A and becomes high, resulting in excessive rotation of engine 10. In particular, when drive wheel 18 is idling, the rotational speed increases sharply, sometimes causing this excessive rotation.
[0042] In this embodiment, the rotational acceleration becomes a second determination value B or higher (time t1), and then the predicted rotational speed becomes a first determination value A or higher (time t2), and torque reduction processing is performed (time t3). As a result, the actual torque of the engine 10 decreases. Thus, by reducing the actual torque of the engine 10 before the actual rotational speed of the engine 10 becomes a first determination value A or higher, excessive rotation of the engine 10 is sufficiently suppressed.
[0043] Furthermore, as described above, the predicted speed is the predicted value of the engine speed 10 after a predetermined time has elapsed from the present. Here, the predetermined time is preferably set to a length of at least the delay time from the start of the torque reduction process until the actual speed of the engine 10 begins to decrease. This is because it is possible to reduce the actual speed from the start of the torque reduction process until the actual speed of the engine 10 becomes a speed exhibiting excessive rotation.
[0044] [Setting the judgment value]
[0045] Next, the setting of the first determination value A and the second determination value B in step S2 will be explained. Figure 4 A is a mapping used to set the first determination value A. The lower the gear position established in the automatic transmission 14, the lower the first determination value A is set to. This is because the lower the gear position, the greater the rotational acceleration of the drive wheel 18 in the specified torque of the engine 10, and the easier it is for the engine 10 to over-rotate. Furthermore, when the automatic transmission 14 is in neutral (N) and the clutch 13C is in the released state, the first determination value A is set to a smaller specified value compared to when the gear position in the automatic transmission 14 is established. In addition, the first determination value A can be different when the automatic transmission 14 is in neutral (N) and the clutch 13C is in the released state.
[0046] Figure 4B is a mapping diagram used to set the second determination value B. Similar to the first determination value A, the lower the gear in the automatic transmission 14, the lower the second determination value B is set to. When the automatic transmission 14 is in neutral (N) and the clutch 13C is released, the second determination value B is set to a smaller predetermined value compared to when the gear in the automatic transmission 14 is engaged. Furthermore, the second determination value B can be different when the automatic transmission 14 is in neutral (N) and the clutch 13C is released.
[0047] Thus, depending on the state of the automatic transmission 14 or the clutch 13C, the more easily the engine 10 over-rotates, the lower the first judgment value A and the second judgment value B are set. This effectively suppresses over-rotation of the engine 10. Furthermore, the gear position established in the automatic transmission 14 can be controlled by the ECU 20 based on the gear position command value issued by the ECU 20 to the automatic transmission 14, or it can be detected by a sensor. Whether the automatic transmission 14 is in neutral (N) position can be detected by the shift position sensor 22. Whether the clutch 13C is in a released state can be controlled by the ECU 20 based on the clutch 13C command value issued by the ECU 20, or it can be detected by a sensor.
[0048] Next, the prediction prerequisites in step S1 will be explained. In this embodiment, the prediction prerequisites require that all of the following conditions be met: condition (1) transmission control based on automatic transmission 14 is not performed; condition (2) partial cylinder operation by the remaining cylinders while stopping combustion of a portion of the cylinders of engine 10 is not performed; and condition (3) the speed of engine 10 is not below a specified value.
[0049] Condition (1) is based on the transmission control of the automatic transmission 14, for example, sometimes controlled to a high rotational acceleration due to transmission bumps or downshifts. To avoid erroneous predictions in such situations. Condition (2) is because, during partial cylinder operation, the torque of the engine 10 is low, and the possibility of over-rotation is small. The specified value in condition (3) is set to a low speed that will not cause over-rotation of the engine 10. Condition (3) is because, in the absence of over-rotation, there is no need to predict over-rotation.
[0050] However, the prediction premise is not limited to satisfying all of the above conditions (1), (2), and (3). For example, if at least one of conditions (1), (2), and (3) is satisfied, the prediction premise can be determined to be valid.
[0051] In addition, Figure 2In step S3 shown in the flowchart, over-rotation of the engine 10 is predicted when the predicted rotational speed is above the first determination value A and the rotational acceleration is above the second determination value B, but this is not a limitation. For example, over-rotation can also be predicted when either the predicted rotational speed is above the first determination value A or the rotational acceleration is above the second determination value B. In this case, over-rotation is not predicted when the predicted rotational speed is below the first determination value A and the rotational acceleration is below the second determination value B. Furthermore, over-rotation can also be predicted when the predicted rotational speed is above the first determination value A without using rotational acceleration. In this case, over-rotation is not predicted when the predicted rotational speed is below the first determination value A. Over-rotation can also be predicted when the rotational acceleration is above the second determination value B without using the predicted rotational speed. In this case, over-rotation is not predicted when the rotational acceleration is below the second determination value B. This is because if at least one of the predicted rotational speed and rotational acceleration is used, over-rotation of the engine 10 can be predicted before the actual rotational speed of the engine 10 reaches the speed at which over-rotation is indicated.
[0052] In the above embodiments, an ECU 20 mounted on a vehicle equipped with an engine 10 as a driving power source was described as an example of a vehicle control device. However, it can also be a vehicle control device mounted on a hybrid vehicle equipped with both an engine and a motor as driving power sources. In the case of a hybrid vehicle, torque reduction processing can be achieved, for example, by regenerating the motor to increase torque in the opposite direction to the rotation direction of the engine.
[0053] In a vehicle equipped with a manual transmission instead of an automatic transmission 14, when the manual transmission is in neutral or the clutch is released when the clutch pedal is depressed, the first determination value A and the second determination value B are set to predetermined values.
[0054] The embodiments of the present invention have been described in detail above, but the present invention is not limited to this specific embodiment. Various modifications and alterations can be made within the scope of the spirit of the present invention as set forth in the claims.
[0055] Symbol Explanation
[0056] 1-Vehicle, 10-Engine, 13C-Clutch, 14-Automatic Transmission, 20-ECU (Vehicle Control Unit, Predictive Unit, Control Unit, Setting Unit).
Claims
1. A vehicle control device, characterized in that, Comprising: A prediction unit that predicts whether the engine will experience overspeed rotation based on at least one of a predicted rotational speed which is a predicted value of the rotational speed of the engine mounted on the vehicle and the rotational acceleration of the engine; And A control unit that performs a torque reduction process to reduce the torque of the engine when it is predicted that the engine will experience overspeed rotation compared to when it is not predicted that the engine will experience overspeed rotation.
2. The vehicle control device according to claim 1, wherein The prediction unit predicts that the engine will experience overspeed rotation in any of the following cases: when the predicted rotational speed is equal to or higher than a first determination value, when the rotational acceleration is equal to or higher than a second determination value, and when the predicted rotational speed is equal to or higher than the first determination value and the rotational acceleration is equal to or higher than the second determination value. The vehicle control device includes a setting unit that sets the first and second determination values to smaller values respectively when the gear position established in a transmission on a power transmission path between the engine and the drive wheels of the vehicle is lower, and sets the first and second determination values to prescribed values when the transmission is in a neutral gear position.
3. The vehicle control device according to claim 2, wherein The setting unit sets the first and second determination values to prescribed values respectively when a clutch provided on the power transmission path is in an open state.
4. The vehicle control device according to claim 2 or 3, wherein The prediction unit predicts whether the engine will experience overspeed rotation when at least one of the following conditions is satisfied: a period during which shift control is not performed by the transmission, a period during which partial cylinder operation is performed by burning with the remaining cylinders while suspending the combustion of a part of the cylinders of the engine, and the rotational speed is not equal to or lower than a prescribed value.
5. The vehicle control device according to any one of claims 1 to 3, wherein The prediction unit calculates the predicted rotational speed based on the current rotational speed of the engine and a value obtained by multiplying the current rotational acceleration by a prescribed time. The prescribed time is set to a length that is longer than or equal to a delay time from the start of the torque reduction process until the rotational speed of the engine starts to decrease.