Vehicle control devices

Abstract

To properly control a transmission.SOLUTION: A control device for a vehicle comprises: a transmission arranged on a power transmission path which connects an engine with wheels; and a control system which includes a processor and a memory communicatively connected to each other and controls the transmission. The control system executes a first gear change mode or a second gear change mode as a gear change mode of the transmission on the basis of driving operation of a driver. When an acceleration operation of the driver is canceled, a gear change ratio of the second gear change mode is on low side relative to a gear change ratio of the first gear change mode. The control system determines whether a driving operation of the driver is in a first or mild driving trend or the driving operation of the driver is in a second or non-mild driving trend. When an engine rotation number exceeds a rotation threshold and the first drive trend is determined in a situation where the second gear change mode is being executed, the control system stops the second gear change mode and executes the first gear change mode.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a vehicle control device provided in a vehicle.

Background Art

[0002] Vehicles such as automobiles are equipped with transmissions such as continuously variable transmissions and automatic transmissions (see Patent Documents 1 to 3). A control unit that controls the transmission controls the transmission ratio of the transmission based on an accelerator operation, vehicle speed, etc. For example, when the accelerator opening increases, the control unit controls the transmission ratio of the transmission to the low side. On the other hand, when the accelerator opening decreases, the control unit controls the transmission ratio of the transmission to the high side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in order to perform gear shift control without causing discomfort to the driver, the control unit controls the transmission not only based on accelerator operation, but also based on brake operation, steering operation, etc. For example, when the amount of brake operation or steering operation is large, the control unit limits the upshift of the transmission to maintain the gear ratio on the lower side, as this indicates that the driver is seeking acceleration response. As a result, even when the accelerator opening decreases as the vehicle enters a corner, the gear ratio can be maintained and the engine speed can be kept higher during cornering, thereby improving acceleration response when exiting the corner. However, maintaining the gear ratio on the lower side even when the accelerator opening decreases can cause the engine speed to increase excessively when driving downhill, which can cause discomfort to the driver. Therefore, it is necessary to control the transmission appropriately so as not to cause discomfort to the driver.

[0005] The objective of this invention is to properly control the transmission. [Means for solving the problem]

[0006] One embodiment of a vehicle control device is a vehicle control device installed in a vehicle, comprising a transmission installed in a power transmission path connecting an engine and wheels, and a control system comprising a processor and memory that are communicated with each other, and which controls the transmission. The control system calculates the driving intensity at predetermined intervals based on the driver's driving operations over a predetermined period or distance. The transmission mode of the aforementioned transmission is determined by the amount of accelerator pedal operation. and vehicle speed Based on this, the gear ratio is controlled in the first gear mode and , the aforementioned operation Rolling strength and vehicle speed There is a second shift mode in which the gear ratio is controlled based on the first threshold. The control system executes the first shift mode when the driving intensity is below the first threshold, and executes the second shift mode when the driving intensity is above the first threshold. The gear ratio of the second shift mode is lower than the gear ratio of the first shift mode when the driver's accelerator operation is released at the same vehicle speed. The control system When driving downhill Accelerator pedal input When the value falls below the second threshold and the amount of brake operation falls below the third thresholdThis is the first operating trend. It was determined that , When driving downhill, if the accelerator operation exceeds the second threshold or the brake operation exceeds the third threshold This is the second operating tendency. and Determine. The control system sets the rotation threshold lower as the downhill gradient of the road surface increases, and also sets the rotation threshold lower as the vehicle speed decreases. The control system, under conditions where the second shift mode is being executed, determines that the engine speed is The aforementioned exceeding the rotation threshold the law of nature ,mosquito Previous If it is determined that the first driving tendency is present, the second shift mode is stopped and the first shift mode is executed. [Effects of the Invention]

[0007] In one embodiment, the vehicle control device, while executing the second shift mode, stops the second shift mode and executes the first shift mode when it determines that the engine speed exceeds a threshold and the vehicle is exhibiting a first driving tendency. This allows for appropriate control of the transmission. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the configuration of a vehicle equipped with a vehicle control device, which is one embodiment of the present invention. [Figure 2] This diagram shows an example of the configuration of a vehicle control system. [Figure 3] This diagram simply illustrates the basic structure of each control unit. [Figure 4] This diagram shows the shift characteristics map used in normal shift mode. [Figure 5] This figure shows an example of a fixed gear ratio used in adaptive shift mode. [Figure 6] This figure shows an example of a target gear used in adaptive shift mode. [Figure 7] This figure shows an example of the correction status for the target gear position. [Figure 8] This timing chart shows an example of how engine speed changes when adaptive shift mode is activated. [Figure 9] A flowchart showing an example of the procedure for executing downhill driving control. [Figure 10]It is a diagram showing an example of a rotation threshold value used in downhill travel control. [Figure 11] It is a flowchart showing an example of a setting procedure for a re-acceleration flag used in downhill travel control. [Figure 12] It is a diagram showing an example of a downshift amount used in downhill travel control. [Figure 13] It is a timing chart showing an example of the execution status of downhill travel control. [Figure 14] It is a timing chart showing an example of the execution status of downhill travel control.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the following description, the same or substantially the same configurations and elements are denoted by the same reference numerals, and repeated descriptions are omitted.

[0010] [Overall Configuration of Vehicle Control Device] FIG. 1 is a diagram showing a configuration example of a vehicle 11 equipped with a vehicle control device 10 according to an embodiment of the present invention. As shown in FIG. 1, the vehicle 11 is equipped with a power train 14 including an engine 12 and a transmission 13. Further, wheels 18 are connected to the output shaft 15 of the power train 14 via a propeller shaft 16 and a differential mechanism 17. The power train 14 shown in the figure is a power train for rear-wheel drive, but it is not limited thereto, and it may be a power train for front-wheel drive or all-wheel drive.

[0011] Figure 2 shows an example of the configuration of a vehicle control device 10. As shown in Figure 2, the powertrain 14 has a continuously variable transmission (CVT) consisting of a primary pulley 20 and a secondary pulley 21 as the transmission 13. The engine 12 is connected to the primary pulley 20 via a primary shaft 22, a forward / reverse switching mechanism 23, and a torque converter 24. The wheels 18 are connected to the secondary pulley 21 via a secondary shaft 25, an output shaft 15, a propeller shaft 16, and a differential mechanism 17. Thus, the engine 12 and the wheels 18 are connected via a power transmission path 26, and the transmission 13 is provided in this power transmission path 26. The power transmission path 26 is a path composed of the torque converter 24, the forward / reverse switching mechanism 23, the propeller shaft 16, and the differential mechanism 17, etc.

[0012] In the illustrated example, a continuously variable transmission (CVT) is used as the transmission 13, but this is not the only option. For example, a planetary gear type automatic transmission may be used as the transmission 13, or a parallel shaft type automatic transmission may be used as the transmission 13. Furthermore, the forward / reverse switching mechanism 23, which switches the rotation direction of the primary pulley 20, is composed of a forward clutch, a reverse brake, and a planetary gear train, etc., which are not shown.

[0013] To control the transmission 13, forward / reverse switching mechanism 23, and other components of the powertrain 14, the powertrain 14 is equipped with a valve unit 30 consisting of multiple electromagnetic valves and oil passages. An oil pump 31, driven by the engine 12, is connected to the valve unit 30. The hydraulic fluid discharged from the oil pump 31 is supplied to the transmission 13, forward / reverse switching mechanism 23, and other components, with the supply destination and pressure controlled by the valve unit 30. A gear shift control unit 32 is also connected to the valve unit 30 to control the transmission 13 and other components via the valve unit 30.

[0014] The intake manifold 33 of the engine 12 is equipped with a throttle valve 34 for adjusting the amount of intake air. The engine 12 is also equipped with injectors 35 for injecting fuel into the intake ports and cylinders, and an ignition system 36 consisting of an igniter and spark plugs. Furthermore, an engine control unit 37 is connected to the throttle valve 34, injectors 35, and ignition system 36, etc., in order to control the operating conditions of the engine 12.

[0015] [Control System] As shown in Figure 2, the vehicle control device 10 is equipped with a control system 40 consisting of multiple electronic control units for controlling the powertrain 14 and the like. The electronic control units constituting the control system 40 include the aforementioned transmission control unit 32 and engine control unit 37, as well as a vehicle control unit 41 that outputs control signals to these control units 32 and 37. These control units 32, 37 and 41 are connected to each other so as to be able to communicate via an in-vehicle network 42 such as CAN or LIN. The vehicle control unit 41 sets operating targets for the engine 12 and transmission 13, etc., based on input information from the various control units 32, 37, 41 and various sensors described later. It then generates control signals according to the operating targets for the engine 12 and transmission 13, etc., and outputs these control signals to the various control units 32 and 37.

[0016] Sensors connected to the vehicle control unit 41 include a vehicle speed sensor 50 for detecting the vehicle speed (the speed at which the vehicle 11 travels), an acceleration sensor 51 for detecting longitudinal acceleration acting on the vehicle 11 in the longitudinal direction, an acceleration sensor 52 for detecting lateral acceleration acting on the vehicle 11 in the width direction, and an engine speed sensor 53 for detecting the engine speed (the rotational speed of the engine 12). Additionally, sensors connected to the vehicle control unit 41 include an accelerator sensor 54 for detecting the operation status of the accelerator pedal, a brake sensor 55 for detecting the operation status of the brake pedal, and a steering angle sensor 56 for detecting the steering angle. Furthermore, sensors connected to the vehicle control unit 41 include a primary rotation speed sensor 57 for detecting the rotational speed of the primary pulley 20, and a secondary rotation speed sensor 58 for detecting the rotational speed of the secondary pulley 21. A start switch 59, operated by the driver when starting the control system 40, is connected to the vehicle control unit 41.

[0017] Figure 3 is a simplified diagram showing the basic structure of each control unit 32, 37, and 41. As shown in Figure 3, each control unit 32, 37, and 41 has a microcontroller 62 into which a processor 60 and memory 61 are incorporated. A predetermined program is stored in the memory 61, and the instruction set of the program is executed by the processor 60. The processor 60 and the memory 61 are connected to each other so as to be able to communicate with each other. In the example shown, the microcontroller 62 incorporates one processor 60 and one memory 61, but this is not limited to this, and the microcontroller 62 may incorporate multiple processors 60 and multiple memories 61.

[0018] Furthermore, each control unit 32, 37, and 41 is equipped with an input conversion circuit 63, a drive circuit 64, a communication circuit 65, an external memory 66, and a power supply circuit 67, etc. The input conversion circuit 63 converts signals input from various sensors into signals that can be input to the microcontroller 62. The drive circuit 64 generates drive signals for actuators such as the valve unit 30 mentioned above, based on signals output from the microcontroller 62. The communication circuit 65 converts signals output from the microcontroller 62 into communication signals for other control units. The communication circuit 65 also converts communication signals received from other control units into signals that can be input to the microcontroller 62. In addition, the power supply circuit 67 supplies a stable power voltage to the microcontroller 62, the input conversion circuit 63, the drive circuit 64, the communication circuit 65, and the external memory 66, etc. Furthermore, data that should be retained even when the power is off is stored in the external memory 66, such as non-volatile memory.

[0019] [Speed ​​control] The gear shift control performed by the control system 40 will now be described. The control system 40 has two gear shift modes for the transmission 13: a normal gear shift mode (first gear shift mode) performed during normal driving and an adaptive gear shift mode (second gear shift mode) performed during sporty driving. The control system 40 will determine when the driver's driving intensity, as described later, reaches a predetermined threshold. (First threshold) When the value falls below D1, the system selects and executes the normal shift mode. However, when the driver's driving intensity exceeds a predetermined threshold D1, the system selects and executes the adaptive shift mode. Here, driving intensity is an index calculated by the control system 40 based on the driver's driving operations, and is an index indicating the degree of gentleness of the driver's driving operations. The control system 40 calculates a smaller driving intensity when driving operations such as accelerator operation are gentle, and a larger driving intensity when driving operations such as accelerator operation are not gentle. The control system 40 calculates and updates the driving intensity at predetermined intervals based on driving operations such as accelerator operation and brake operation over a predetermined period or predetermined driving distance.

[0020] For example, situations in which driving intensity is calculated to be high include when the amount of accelerator pedal operation (hereinafter referred to as accelerator opening) is large and the speed of accelerator pedal operation is fast. Also, situations in which driving intensity is calculated to be high include when the amount of brake pedal operation is large and the speed of brake pedal operation is fast, when the amount of steering operation is large and the speed of steering operation is fast. Furthermore, situations in which driving intensity is calculated to be high include when the vehicle speed is high, when the longitudinal acceleration is large and when the lateral acceleration is large. On the other hand, situations in which driving intensity is calculated to be low include when the accelerator opening is small and the speed of accelerator pedal operation is slow. Also, situations in which driving intensity is calculated to be low include when the amount of brake pedal operation is small and the speed of brake pedal operation is slow, when the amount of steering operation is small and when the speed of steering operation is slow. Furthermore, situations in which driving intensity is calculated to be low include when the vehicle speed is low, when the longitudinal acceleration is small and when the lateral acceleration is small.

[0021] <Shift control: Normal shift mode> This section describes the normal shift mode during normal driving. Figure 4 shows the shift characteristic map used in the normal shift mode. The control system 40 refers to the shift characteristic map based on the accelerator opening and vehicle speed and sets the target gear ratio to be used in the normal shift mode. As shown in Figure 4, the shift characteristic map has a characteristic line Low that shows the maximum gear ratio on the low side and a characteristic line High that shows the minimum gear ratio on the high side. In addition, as shown by the dashed lines, the shift characteristic map has multiple characteristic lines that correspond to the accelerator opening, i.e., the required driving force. The gear ratio is the ratio (Np / Ns) of the rotational speed of the primary pulley 20 (primary rotational speed Np) to the rotational speed of the secondary pulley 21 (secondary rotational speed Ns). Therefore, a larger gear ratio value means that the gear ratio is on the low side, and a smaller gear ratio value means that the gear ratio is on the high side.

[0022] As shown in Figure 4, the more the accelerator opening increases due to the depressing of the accelerator pedal, that is, the more the required driving force on the vehicle 11 increases, the more the characteristic curve in the direction of arrow α is selected. On the other hand, the more the accelerator opening decreases due to the release of the accelerator pedal, that is, the more the required driving force on the vehicle 11 decreases, the more the characteristic curve in the direction of arrow β is selected. For example, as shown by arrow γ, when the accelerator pedal is pressed while driving at vehicle speed V1, the target primary rotational speed is increased from "Npa" to "Npb", and the target gear ratio of the transmission 13 is continuously controlled from "Tra" to the lower "Trb". In this way, in the normal shift mode, the target gear ratio is set based on the accelerator opening and vehicle speed, and the groove widths of the primary pulley 20 and secondary pulley 21 are controlled toward this target gear ratio.

[0023] <Shift control: Adaptive shift mode> This section describes the adaptive shift mode during sporty driving. Figure 5 shows an example of a fixed gear ratio used in the adaptive shift mode, and Figure 6 shows an example of a target gear used in the adaptive shift mode. As shown in Figure 5, the adaptive shift mode has multiple fixed gear ratios R1 to R10 set as the target gear ratio, or target gear, of the shift mode. Also, as shown in Figure 6, the control system 40 sets the target gear for the adaptive shift mode based on the vehicle speed and driving intensity. In other words, the control system 40 sets the target gear on the high gear side as the vehicle speed increases, and sets the target gear on the low gear side as the vehicle speed decreases. Furthermore, the control system 40 sets the target gear on the low gear side as the driving intensity increases. low While setting a target gear on the speed side, as the driving intensity decreases... high Set the target gear for the speed gear.

[0024] Furthermore, in adaptive shift mode, the target gear is corrected based on the road surface gradient. Figure 7 shows an example of the correction of the target gear. As shown in Figure 7, as the uphill gradient of the road surface increases, the target gear is corrected towards a lower gear, while as the downhill gradient of the road surface increases, the target gear is corrected towards a higher gear. In other words, if the uphill gradient of the road surface is "S1", the target gear set based on Figure 6 is corrected by one step towards a lower gear. On the other hand, if the downhill gradient of the road surface is "-S2", the target gear set based on Figure 6 is corrected by one step towards a higher gear. The control system 40 can calculate the gradient of the road surface based on the longitudinal acceleration detected by the acceleration sensor 51.

[0025] Figure 8 is a timing chart showing an example of the engine speed change in adaptive shift mode. Figure 8 shows the driving conditions from corner entry to corner exit. As shown in Figure 8 at time t1, the driving intensity calculated based on accelerator operation etc. exceeds a predetermined threshold D1 (symbol a1), so the adaptive shift mode is executed as the shift mode of the transmission 13. Subsequently, as shown in time t2, when the vehicle 11 enters a corner, the driver releases the accelerator pedal and the accelerator opening decreases (symbol b1). In this way, even when the accelerator opening decreases, as shown in Figure 6, the target gear of the adaptive shift mode is set based on the vehicle speed and driving intensity, so the target gear, that is, the gear ratio of the transmission 13 is maintained (symbol c1), and an excessive decrease in engine speed is suppressed (symbol d1). Then, as shown at time t3, when the vehicle 11 exits a corner after cornering, the driver presses the accelerator pedal and the accelerator opening begins to increase (symbol b2). At this time, the adaptive shift mode keeps the engine speed higher during cornering (symbol d2), which improves the acceleration responsiveness of the vehicle 11 when exiting the corner.

[0026] In contrast, as shown by the dashed line in Figure 8, if the normal driving mode is executed from corner entry to corner exit, the engine speed during cornering decreases significantly, making it difficult to improve the acceleration responsiveness of the vehicle 11 when exiting the corner. In other words, as shown at time t1 in Figure 8, the driving intensity calculated based on accelerator operation, etc., falls below a predetermined threshold D1 (symbol e1), so the normal shift mode is executed as the shift mode of the transmission 13. Subsequently, as shown at time t2, when the vehicle 11 enters a corner, the driver releases the accelerator pedal and the accelerator opening decreases (symbol b1). In this case, as shown in Figure 4, the target gear ratio of the normal shift mode is set based on the accelerator opening, i.e., the required driving force, so the target gear ratio is upshifted to the high side (symbol f1), and the engine speed decreases significantly (symbol g1). Then, as shown at time t3, when vehicle 11 exits a corner after cornering, the driver presses the accelerator pedal and the accelerator opening begins to increase (symbol b2). At this time, the engine speed decreases significantly during cornering due to the normal shift mode (symbol g2), which reduces the acceleration responsiveness of vehicle 11 when exiting the corner.

[0027] Thus, the adaptive shift mode is a shift mode that controls the gear ratio of the transmission 13 to the lower side compared to the normal shift mode when the driver's accelerator operation is released. By executing such an adaptive shift mode, even when the accelerator pedal is released when entering a corner, the gear ratio can be kept on the lower side and the engine speed can be increased, thereby improving the acceleration response of the vehicle 11. However, keeping the gear ratio on the lower side even when the accelerator operation is released was a factor that caused the engine speed to increase excessively when driving downhill. Since such an excessive increase in engine speed is a factor that causes discomfort to the driver, the control system 40 executes the adaptive shift mode in a way that does not cause discomfort to the driver by performing downhill driving control, which will be described later.

[0028] [Downhill Driving Control (Flowchart)] The downhill driving control performed by the control system 40 will be described below. Figure 9 is a flowchart showing an example of the procedure for performing downhill driving control, and Figure 10 shows an example of the rotation threshold N1 used in downhill driving control. Figure 11 is a flowchart showing an example of the procedure for setting the re-acceleration flag used in downhill driving control, and Figure 12 shows an example of the downshift amount used in downhill driving control. Each step shown in the flowchart of Figure 9 shows a process performed by one or more processors 60 that constitute the control system 40. Furthermore, the downhill driving control shown in Figure 9 is a control performed by the control system 40 at predetermined intervals after the start switch 59 is operated by the driver and the control system 40, consisting of the vehicle control unit 41, etc., is activated.

[0029] As shown in Figure 9, step S10 determines whether or not the adaptive shift mode is being executed. If it is determined in step S10 that the adaptive shift mode is being executed, the process proceeds to step S11, where it is determined whether or not the engine speed Ne exceeds a predetermined rotation threshold N1. Here, as shown in Figure 10, the rotation threshold N1 is set to decrease as the vehicle speed decreases and as the downhill gradient of the road surface increases. The rotation threshold N1 is a threshold that indicates the boundary between whether or not an increase in engine speed Ne causes discomfort to the driver.

[0030] In step S11, if it is determined that the engine speed Ne exceeds the rotation threshold N1, that is, if it is determined that the increase in engine speed Ne causes discomfort to the driver, the process proceeds to step S12, where it is determined whether the re-acceleration flag, which indicates the driver's intention to accelerate, is set to "0". In step S12, if it is determined that the re-acceleration flag is set to "0", that is, if it is determined that the driver does not intend to accelerate, the process proceeds to step S13, where the adaptive shift mode is deactivated and the normal shift mode is executed.

[0031] Here, the re-acceleration flag is a flag set based on the driver's driving actions. It is set to "1" when the driver intends to accelerate, and to "0" when the driver does not intend to accelerate. In other words, the re-acceleration flag is set to "0" based on the driving actions when the control system 40 determines that the driving actions are of the first driving tendency, which is gentle. Conversely, the re-acceleration flag is set to "1" based on the driving actions when the control system 40 determines that the driving actions are of the second driving tendency, which is not gentle. The procedure for setting the re-acceleration flag will be explained below using the flowchart in Figure 11.

[0032] As shown in Figure 11, if all the conditions shown in steps S20 to S25 are met, the process proceeds to step S26 and the re-acceleration flag is set to "0". On the other hand, if any of the conditions shown in steps S20 to S25 are not met, the process proceeds to step S27 and the re-acceleration flag is set to "1". Note that in the flowchart of Figure 11, the accelerator opening Acp is the amount the accelerator pedal is pressed, and the accelerator operation speed Sacp is the speed at which the accelerator pedal is pressed and released. Also, the brake operation amount Bkp is the amount the brake pedal is pressed, and the brake operation speed Sbkp is the speed at which the brake pedal is pressed and released.

[0033] As shown in Figure 11, in step S20, it is determined whether the accelerator opening Acp is less than or equal to a predetermined threshold (second threshold) X1, and in step S21, it is determined whether the absolute value of the accelerator operation speed Sacp is less than or equal to a predetermined threshold X2. Also, in step S22, it is determined whether the brake operation amount Bkp is less than or equal to a predetermined threshold (Third threshold)In step S23, it is determined whether X is less than or equal to X3, and in step S24, it is determined whether the absolute value of the brake operation speed Sbkp is less than or equal to a predetermined threshold X4. Furthermore, in step S24, it is determined whether the absolute value of the change rate of lateral acceleration Sg1 is less than or equal to a predetermined threshold X5, and in step S25, it is determined whether the driving intensity Ld is less than or equal to a predetermined threshold D2. That is, if any of the driving operations performed by the driver (such as accelerator operation or brake operation) is active, the control system 40 determines that the driver intends to accelerate and sets the re-acceleration flag to "1". On the other hand, if all of the driving operations performed by the driver (such as accelerator operation or brake operation) are passive, the control system 40 determines that the driver does not intend to accelerate and sets the re-acceleration flag to "0".

[0034] As explained using Figure 9, if in step S11 it is determined that the engine speed Ne exceeds the rotation threshold N1, and in step S12 it is determined that the re-acceleration flag indicating the driver's intention to accelerate is set to "0", then the process proceeds to step S13, where the adaptive shift mode is deactivated and the normal shift mode is executed. In other words, in the adaptive shift mode, if the engine speed is high despite the driver's intention to accelerate being weak, there is a risk of causing discomfort to the driver, so the shift mode is switched from the adaptive shift mode to the normal shift mode. This allows the transmission 13 to be appropriately upshifted according to the driving conditions and prevents an excessive increase in engine speed Ne, thus allowing the transmission 13 to be appropriately controlled without causing discomfort to the driver.

[0035] Next, as shown in Figure 9, if it is determined in step S12 that the re-acceleration flag is set to "1", that is, if it is determined that the driver intends to accelerate, the process proceeds to step S14, and the adaptive shift mode for improving acceleration responsiveness is maintained. Thus, even if the engine speed Ne exceeds the rotation threshold N1, if the re-acceleration flag is set to "1", the adaptive shift mode is maintained to ensure acceleration responsiveness. However, even if it is determined that the driver intends to accelerate, an excessive increase in engine speed Ne can cause discomfort to the driver, so the process proceeds to step S15, where it is determined whether the engine speed Ne exceeds the upshift threshold N2, which is higher than the rotation threshold N1. In step S15, if it is determined that the engine speed Ne exceeds the upshift threshold N2, even if it is determined that the driver intends to accelerate, the process proceeds to step S16, and the transmission 13 performs an upshift to lower the engine speed Ne. This makes it possible to suppress an excessive increase in engine speed Ne associated with maintaining the gear ratio, even when driving downhill while maintaining adaptive shift mode.

[0036] Furthermore, if in step S11 it is determined that the engine speed Ne is below the rotation threshold N1, that is, if there is no increase in engine speed Ne that would cause discomfort to the driver in adaptive shift mode, the process proceeds to step S17, where the adaptive shift mode is maintained, and then to step S18, where it is determined whether the engine speed Ne falls below the downshift threshold N3, which is lower than the rotation threshold N1. If in step S18 it is determined that the engine speed Ne falls below the downshift threshold N3, it means that the engine speed Ne has decreased excessively, and the acceleration responsiveness in adaptive shift mode has decreased. For this reason, the process proceeds to step S19, where the transmission 13 performs a downshift to raise the engine speed Ne.

[0037] Here, as shown in Figure 12, the control system 40 sets the amount of change in the gear ratio (downshift amount) during the downshift in step S19 based on the vehicle speed and the downhill gradient. In other words, the control system 40 sets the downshift amount to be larger as the vehicle speed increases, and smaller as the vehicle speed decreases. Also, the control system 40 sets the downshift amount to be larger as the downhill gradient decreases, and smaller as the downhill gradient increases. By setting the downshift amount based on the vehicle speed and the downhill gradient in this way, the engine speed Ne can be controlled within an appropriate range, thereby improving acceleration responsiveness while ensuring the quietness of the adaptive shift mode.

[0038] Increasing the downshift amount means increasing the change in gear ratio before and after the downshift, while decreasing the downshift amount means decreasing the change in gear ratio before and after the downshift. Furthermore, although the explanation above sets the downshift amount based on vehicle speed and downhill gradient, it is not limited to this, and the downshift amount may be set based on vehicle speed alone, or on downhill gradient alone.

[0039] [Downhill Driving Control (Timing Chart)] Next, the downhill driving control described above will be explained using a timing chart. Figures 13 and 14 are timing charts showing examples of the execution status of downhill driving control. Figure 13 shows the situation when switching from adaptive shift mode to normal shift mode, and when performing an upshift while maintaining adaptive shift mode. Figure 14 shows the situation when performing a downshift while maintaining adaptive shift mode.

[0040] <Downhill driving control: Upshift> As shown in Figure 13 at time t1, the driver's driving intensity exceeds the threshold D1 (symbol a1), and the adaptive shift mode is executed as the shift mode (symbol b1). As shown at time t2, the re-acceleration flag is set to "0" due to gentle accelerator operation, etc. (symbol c1), and as shown at time t3, when the engine speed rises to the rotation threshold N1 (symbol d1), the shift mode is switched from adaptive shift mode to normal shift mode (symbol b2). In other words, the control system 40 stops the adaptive shift mode and executes the normal shift mode when, while the adaptive shift mode is being executed, the engine speed exceeds the rotation threshold N1 and the re-acceleration flag is set to "0" due to gentle driving operation.

[0041] Thus, in adaptive shift mode, if the engine speed is high despite the driver's weak intention to accelerate, the shift mode is switched from adaptive shift mode to normal shift mode. As a result, the gear ratio of the transmission 13 is controlled to the high side (symbol e1), preventing an excessive increase in engine speed. In other words, the shift mode can be appropriately switched from adaptive shift mode to normal shift mode, allowing the transmission 13 to be controlled appropriately without causing any discomfort to the driver.

[0042] Furthermore, as shown by the dashed line in Figure 13, at time t3 when the engine speed reaches the rotation threshold N1, if, for example, the driver's accelerator input remains large and the re-acceleration flag continues to be set to "1" (symbol f1), the transmission mode is maintained in adaptive transmission mode (symbol g1). Subsequently, if the engine speed continues to increase and, as shown at time t4, reaches an upshift threshold N2 which is higher than the rotation threshold N1 (symbol h1), an upshift is performed while maintaining adaptive transmission mode (symbol i1), and the engine speed is reduced (symbol h2).

[0043] In other words, the control system 40 performs an upshift while maintaining the adaptive shift mode if, while the adaptive shift mode is running, the engine speed exceeds the upshift threshold N2, which is higher than the rotation threshold N1, and the re-acceleration flag is set to "1" while the driving input remains large. This makes it possible to suppress an excessive increase in engine speed due to maintaining the gear ratio, even when driving downhill while maintaining the adaptive shift mode. As shown by the symbol Xa in Figure 13, in an upshift while maintaining the adaptive shift mode, the gear ratio after the upshift is set to a larger value, i.e., a lower value, compared to when the shift mode is switched to the normal shift mode, in order to ensure acceleration responsiveness in response to accelerator operation.

[0044] <Downhill driving control: Downshift> As shown in Figure 14 at time t1, the driver's driving intensity exceeds the threshold D1 (symbol a1), and the adaptive shift mode is executed as the shift mode (symbol b1). Subsequently, as shown at time t2, if the engine speed drops to a downshift threshold N3, which is lower than the rotation threshold N1, due to uphill driving or vehicle braking (symbol d1), a downshift is executed while maintaining the adaptive shift mode (symbol d1), and the engine speed is increased (symbol c2).

[0045] In other words, when the adaptive shift mode is in operation, the control system 40 performs a downshift while maintaining the adaptive shift mode if the engine speed falls below the downshift threshold N3, which is lower than the rotation threshold N1. This ensures that the acceleration responsiveness of the adaptive shift mode is maintained even when the engine speed decreases due to uphill driving or vehicle braking, by performing a downshift appropriately.

[0046] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. In the above description, the control system 40 is configured by a plurality of control units 32, 37, and 41, but it is not limited to this. For example, the control system 40 may be configured by a single control unit. Also, in the above description, a vehicle 11 equipped only with an engine 12 as a power source is controlled, but it is not limited to this, and a hybrid vehicle equipped with an engine 12 and an electric motor as power sources may also be controlled.

[0047] In the above description, the gear ratio is continuously changed in normal shift mode, but this is not the only way; the gear ratio may also be changed in steps. Also, in the above description, all the conditions shown in steps S20 to S25 of Figure 11 are checked when setting the re-acceleration flag, but this is not the only way. For example, the re-acceleration flag may be set to "0" or "1" based on at least one of the conditions shown in steps S20 to S25. [Explanation of Symbols]

[0048] 10 Vehicle control devices 11 vehicles 12 Engines 13. Transmission 18 wheels 26 Power transmission path 40 Control Systems Ne Engine speed N1 rotation threshold N2 Upshift Threshold N3 Downshift Threshold

Claims

1. A vehicle control device installed in a vehicle, A transmission is provided in the power transmission path connecting the engine and the wheels, A control system comprising a processor and memory connected to each other in a manner that enables communication, for controlling the transmission, It has, The control system calculates the driving intensity at predetermined intervals based on the driver's driving operations over a predetermined period or distance, The transmission has two transmission modes: a first transmission mode in which the gear ratio is controlled based on the accelerator pedal input and vehicle speed, and a second transmission mode in which the gear ratio is controlled based on the driving intensity and vehicle speed. The control system executes the first shift mode when the operating intensity falls below a first threshold, and executes the second shift mode when the operating intensity exceeds the first threshold. The gear ratio of the second shift mode is lower than the gear ratio of the first shift mode when the driver releases the accelerator at the same vehicle speed. The control system determines that a first driving tendency exists when the accelerator operation amount falls below a second threshold and the brake operation amount falls below a third threshold during downhill driving, and determines that a second driving tendency exists when the accelerator operation amount exceeds the second threshold or the brake operation amount exceeds the third threshold during downhill driving. The control system sets the rotation threshold lower as the downhill gradient of the road surface increases, and also sets the rotation threshold lower as the vehicle speed decreases. The control system, while executing the second shift mode, determines that the engine speed exceeds the rotation threshold and is in the first driving condition, and then stops the second shift mode and executes the first shift mode. Vehicle control device.

2. In the vehicle control device according to claim 1, The control system, while executing the second shift mode, determines that the engine speed exceeds an upshift threshold which is higher than the rotation threshold, and that the second driving tendency is present, and executes an upshift of the transmission. Vehicle control device.

3. In the vehicle control device according to claim 1 or 2, The control system, while executing the second shift mode, performs a downshift of the transmission when the engine speed falls below a downshift threshold which is lower than the rotation threshold. Vehicle control device.

Images