Vehicle behavior control device

Abstract

Provided is a vehicle behavior control device capable of improving the sense of linearity and the responsiveness of vehicle behavior to a steering operation without causing a driver to feel a strong sense of control intervention, and improving ride comfort and the sense of stability of a vehicle attitude. A vehicle behavior control device for controlling behavior of a vehicle (1) in which front wheels (2) are steered, includes a PCM (14), acquires a steering speed associated with a jerk degree in a vehicle width direction of the vehicle, sets a torque reduction flag indicating whether or not a condition for reducing an output torque of an engine (4) is satisfied based on the steering speed, and controls behavior of the vehicle (1) based on the torque reduction flag. When the torque reduction flag is set to a True indicating a state in which a condition for reducing the torque is satisfied, the torque reduction is started.

Description

[0001] This application is a divisional application of the original application with application date of March 30, 2017, application number 201780016206.5, and invention name “Behavior Control Device for Vehicle”. Technical Field

[0002] The present invention relates to a vehicle behavior control device, and in particular to a vehicle behavior control device for controlling the behavior of a front-wheel steering vehicle. Background Art

[0003] In the past, it is known that when the behavior of a vehicle becomes unstable due to slipping, the behavior of the vehicle is controlled in a safe direction (lateral slip prevention device, etc.). Specifically, when the vehicle is turning, it is detected whether the vehicle has an under-steering or over-steering behavior, and appropriate deceleration is applied to the wheels to suppress the under-steering or over-steering.

[0004] On the other hand, the following vehicle motion control device is known: unlike the control used to improve safety in a driving state where the vehicle behavior is unstable as described above, the device automatically performs acceleration and deceleration in conjunction with steering wheel operation in a daily driving area to reduce lateral slip in an extreme driving area (for example, refer to Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5193885 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, if the acceleration and deceleration are automatically controlled by instructions from the control device as described in the above-mentioned patent document 1, acceleration and deceleration may not be in accordance with the driver's intention, and the driver will feel a strong sense of control intervention. On the other hand, if the control gain is reduced to suppress the sense of control intervention, the effect of acceleration and deceleration control will also decrease.

[0010] Furthermore, the prior art described in Patent Document 1 mainly focuses on achieving the same vehicle motion as a professional driver by allowing the driver to perform steering operations for turning, and does not necessarily improve the responsiveness and linearity of the vehicle's behavior to normal steering operations.

[0011] The present invention is made to solve the above-mentioned problems of the prior art, and its purpose is to provide a vehicle behavior control device that will not make the driver feel a strong sense of control intervention, thereby improving the responsiveness and linearity of the vehicle behavior to the steering operation, and also improving the stability of the vehicle posture and ride comfort.

[0012] Technical means used to solve the problem

[0013] In order to achieve the above-mentioned purpose, the vehicle behavior control device of the present invention controls the behavior of a vehicle with front-wheel steering, and comprises: a lateral jerk associated quantity acquisition unit, which acquires a lateral jerk associated quantity associated with the jerk of the vehicle in the vehicle width direction; a driving force reduction flag setting unit, which sets a driving force reduction flag based on the lateral jerk associated quantity, and the driving force reduction flag indicates whether the conditions for reducing the driving force of the vehicle are met; and a driving force reduction unit, which starts reducing the driving force of the vehicle when the driving force reduction flag is set to a true value indicating a state in which the conditions for reducing the driving force of the vehicle are met.

[0014] In the present invention thus constituted, the driving force reduction unit starts reducing the driving force of the vehicle when the driving force reduction flag is set to a true value indicating a state that satisfies the condition for reducing the driving force of the vehicle based on the lateral jerk-related amount, so that the driving force can be reduced immediately when the vehicle generates lateral jerk, so that the vertical load of the front wheel can control the behavior of the vehicle with good responsiveness to the steering operation of the driver, thereby preventing the driver from feeling a strong sense of control intervention, and improving the responsiveness and linearity of the vehicle behavior to the steering operation. In addition, by accurately achieving the behavior that meets the driver's intention, a small correction angle is not required, so the stability of the vehicle posture and the ride comfort can be improved.

[0015] Furthermore, in the present invention, preferably, when the lateral jerk-related amount exceeds a predetermined threshold value, the driving force reduction flag setting means sets the driving force reduction flag to a true value.

[0016] In the present invention thus constructed, when the lateral jerk correlation amount is below a threshold value, the vehicle can be restrained from excessively reacting to a slight steering operation, thereby causing the vehicle's behavior when traveling straight to not cause a sense of discomfort to the driver and enabling accurate behavior that meets the driver's intention.

[0017] Furthermore, in the present invention, it is preferable that the lateral jerk-related amount is a turning speed of the vehicle.

[0018] In the present invention thus constituted, the driving force can be immediately reduced as the driver starts the wheel turning operation, thereby controlling the behavior of the vehicle with good responsiveness to the driver's wheel turning operation.

[0019] Effects of the invention:

[0020] According to the vehicle behavior control device of the present invention, the responsiveness and linearity of the vehicle behavior to the steering operation can be improved without making the driver feel a strong sense of control intervention, and the stability of the vehicle posture and the riding comfort can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a block diagram showing the overall configuration of a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention.

[0022] Figure 2 : is a block diagram showing the circuit configuration of a vehicle behavior control device according to an embodiment of the present invention.

[0023] Figure 3 This is a flowchart of an engine control process in which the vehicle behavior control device according to the embodiment of the present invention controls the engine.

[0024] Figure 4 This is a flowchart of a torque reduction amount determination process for determining a torque reduction amount in the vehicle behavior control device according to the embodiment of the present invention.

[0025] Figure 5 This is a map showing the relationship between the target additional deceleration and the steering speed determined by the vehicle behavior control device according to the embodiment of the present invention.

[0026] Figure 6 1. The present invention is a timing diagram showing time changes in parameters related to engine control when a vehicle equipped with a vehicle behavior control device according to an embodiment of the present invention turns. Graph (a) is a plan view schematically showing a vehicle turning right. Graph (b) is a line diagram showing changes in a steering angle of the vehicle turning right. Graph (c) is a line diagram showing changes in a steering speed of the vehicle turning right. Graph (d) is a line diagram showing the value of a torque reduction flag set based on the steering speed. Graph (e) is a line diagram showing changes in an additional deceleration determined based on the steering speed and the torque reduction flag. Graph (f) is a line diagram showing changes in a torque reduction amount determined based on the additional deceleration. Graph (g) is a line diagram showing changes in a final target torque determined based on a basic target torque and the torque reduction amount.

[0027] Fig. 7A This is a graph showing changes in longitudinal acceleration and lateral acceleration when a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention turns.

[0028] Figure 7B This is a graph showing changes in longitudinal acceleration and lateral acceleration when a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention turns.

[0029] Figure 8 It is a line graph showing the measurement results of the vehicle behavior when a vehicle equipped with a vehicle behavior control device according to an embodiment of the present invention is turned, wherein graph (a) is a line graph showing the change in the steering angle of the vehicle, graph (b) is a line graph showing the change in the lateral jerk generated by the vehicle, graph (c) is a line graph showing the value of a torque reduction flag set based on the steering speed, graph (d) is a line graph showing the change in the driving torque of the front wheel drive, and graph (e) is a line graph showing the change in the front and rear jerk generated by the vehicle.

[0030] Fig. 9 The diagram shows how lateral acceleration and longitudinal acceleration are generated when a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention and a vehicle not equipped with the vehicle behavior control device respectively turn.

[0031] Fig.10 The diagram shows how roll and pitch occur when a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention and a vehicle not equipped with the vehicle behavior control device respectively turn.

[0032] Fig.11A This is a schematic diagram showing the vehicle posture by the extension and contraction amount of the suspension of each wheel, and is a diagram showing the vehicle posture when parallel rolling occurs.

[0033] Fig. 11B This is a schematic diagram showing the vehicle posture by the extension and contraction amount of the suspension of each wheel, and is a diagram showing the vehicle posture when a diagonal roll occurs.

[0034] Fig. 12A It is a line graph showing how the vertical load on the front wheels changes when a vehicle equipped with a vehicle behavior control device according to an embodiment of the present invention and a vehicle not equipped with the vehicle behavior control device respectively turn, and is a line graph showing the change in the vertical load on the front inner wheel caused by the left and right load shifts.

[0035] Fig. 12B It is a line graph showing how the vertical load on the front wheels changes when a vehicle equipped with the vehicle behavior control device according to an embodiment of the present invention and a vehicle not equipped with the vehicle behavior control device respectively turn, and is a line graph showing the change in the vertical load on the front wheels caused by the deceleration of the vehicle.

[0036] Explanation of symbols:

[0037] 1 Vehicle

[0038] 2 Front wheels

[0039] 4 Engine

[0040] 6 Steering wheels

[0041] 8 Steering angle sensor

[0042] 10 Throttle opening sensor

[0043] 12 Vehicle speed sensor

[0044] 14 PCM

[0045] 16 Basic target torque determination unit

[0046] 18 Torque reduction amount determination unit

[0047] 20 Final target torque determination unit

[0048] 22 Engine Control Unit DETAILED DESCRIPTION

[0049] Hereinafter, a vehicle behavior control device according to an embodiment of the present invention will be described with reference to the drawings.

[0050] Firstly based on Figure 1 A vehicle behavior control device equipped with an embodiment of the present invention will be described. Figure 1 It is a block diagram showing the overall configuration of a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention.

[0051] exist Figure 1 In the figure, reference numeral 1 indicates a vehicle equipped with the vehicle behavior control device of the present embodiment. A pair of driving wheels ( Figure 1 In the example of FIG. 4 , the engine 4 drives the left and right front wheels 2). The engine 4 is an internal combustion engine such as a gasoline engine or a diesel engine.

[0052] The vehicle 1 also includes a steering angle sensor 8 for detecting the rotation angle of the steering wheel 6, an accelerator opening sensor 10 for detecting the opening of the accelerator pedal (accelerator opening), and a vehicle speed sensor 12 for detecting the vehicle speed. Each of these sensors outputs its detection value to a PCM (Power-train Control Module) 14.

[0053] Next, based on Figure 2 A circuit configuration of a vehicle behavior control device according to an embodiment of the present invention will be described. Figure 2 : is a block diagram showing the circuit configuration of a vehicle behavior control device according to an embodiment of the present invention.

[0054] In addition to the detection signals of the above-mentioned sensors 8 to 12, the PCM14 of the embodiment of the present invention also outputs control signals based on the detection signals output by various sensors that detect the operating status of the engine 4, so as to control various parts of the engine 4 (such as the throttle valve, turbocharger, variable valve mechanism, ignition device, fuel injection valve, EGR device, etc.).

[0055] The PCM 14 includes: a basic target torque determination unit 16 that determines the basic target torque based on the operating state of the vehicle 1 including the operation of the accelerator pedal; a torque reduction amount determination unit 18 that determines the torque reduction amount for adding deceleration to the vehicle 1 based on an amount (lateral jerk-related amount) associated with the jerk (acceleration) in the vehicle width direction of the vehicle 1; a final target torque determination unit 20 that determines the final target torque based on the basic target torque and the torque reduction amount; and an engine control unit 22 that controls the engine 4 to output the final target torque. In this embodiment, a case where the torque reduction amount determination unit 18 uses the steering speed of the vehicle 1 as the lateral jerk-related amount is described.

[0056] Each component of these PCM14 is composed of a computer having: a CPU, various programs compiled and executed on the CPU (including basic control programs such as OS, and application programs that are started on the OS and implement specific functions), and internal memory such as ROM and RAM for storing programs and various data.

[0057] Although details will be described later, the PCM 14 corresponds to the vehicle behavior control device in the present invention, and functions as a lateral jerk-related amount acquisition unit, a drive force reduction flag setting unit, and a drive force reduction unit.

[0058] Next, based on Figures 3 to 5 The processing performed by the vehicle behavior control device is described.

[0059] Figure 3 1 is a flowchart of an engine control process in which the vehicle behavior control device according to the embodiment of the present invention controls the engine 4. Figure 4 is a flowchart of a torque reduction amount determination process for determining a torque reduction amount in a vehicle behavior control device according to an embodiment of the present invention. Figure 5 This is a map showing the relationship between the target additional deceleration and the steering speed determined by the vehicle behavior control device according to the embodiment of the present invention.

[0060] Figure 3 The engine control process is started when the vehicle 1 is ignited and the vehicle behavior control device is powered on, and is repeatedly executed.

[0061] After the engine control process starts, if Figure 3 As shown, in step S1, the PCM 14 obtains various information related to the operating state of the vehicle 1. Specifically, the PCM 14 obtains detection signals output by the various sensors, including the steering angle detected by the steering angle sensor 8, the accelerator opening detected by the accelerator opening sensor 10, the vehicle speed detected by the vehicle speed sensor 12, and the gear stage currently set in the transmission of the vehicle 1, as information related to the operating state.

[0062] Next, in step S2, the basic target torque determination unit 16 of the PCM 14 sets the target acceleration based on the operating state of the vehicle 1 including the operation of the accelerator pedal obtained in step S1. Specifically, the basic target torque determination unit 16 selects an acceleration characteristic map corresponding to the current vehicle speed and gear position from the acceleration characteristic maps (pre-made and stored in the memory) prescribed for various vehicle speeds and various gear positions, and determines the target acceleration corresponding to the current accelerator opening with reference to the selected acceleration characteristic map.

[0063] Next, in step S3, the basic target torque determination unit 16 determines the basic target torque of the engine 4 for achieving the target acceleration determined in step S2. In this case, the basic target torque determination unit 16 determines the basic target torque within the range of torque that the engine 4 can output based on the current vehicle speed, gear position, road gradient, road surface μ, etc.

[0064] In parallel with the processing of steps S2 and S3, in step S4, the torque reduction amount determination unit 18 performs a torque reduction amount determination process for determining a torque reduction amount for adding deceleration to the vehicle 1 based on the turning operation. Figure 4 Provide explanation.

[0065] like Figure 4 As shown, after the torque reduction amount determination process starts, in step S21 , the torque reduction amount determination unit 18 calculates the steering speed based on the steering angle acquired in step S1 .

[0066] Next, in step S22, the torque reduction amount determination unit 18 determines whether the steering speed is greater than a predetermined threshold value T S1 .

[0067] As a result, the steering speed is greater than the threshold value T S1 In the case of the above, the process proceeds to step S23, and the torque reduction amount determination unit 18 sets the torque reduction flag to True (true value) indicating the state in which the condition for reducing the torque is satisfied. The torque reduction flag indicates whether the condition for reducing the output torque of the engine 4 in order to add deceleration to the vehicle 1 is satisfied.

[0068] Next, in step S24, the torque reduction amount determination unit 18 obtains a target additional deceleration based on the steering speed. The target additional deceleration is a deceleration that should be added to the vehicle 1 in response to the wheel turning operation in order to accurately achieve vehicle behavior that meets the driver's intention.

[0069] Specifically, the torque reduction amount determination unit 18 is based on Figure 5The target additional deceleration corresponding to the steering speed calculated in step S21 is obtained by referring to the relationship between the target additional deceleration and the steering speed shown in the map of FIG.

[0070] Figure 5 The horizontal axis represents the steering speed, and the vertical axis represents the target additional deceleration. Figure 5 As shown, the turning speed is the threshold value T S In the following cases, the corresponding target additional deceleration is 0. That is, the steering speed is the threshold value T S1 In the following cases, the PCM 14 stops the control for adding deceleration to the vehicle 1 (specifically, reducing the output torque of the engine 4 ) based on the turning operation.

[0071] On the other hand, the steering speed exceeds the threshold T S1 In the case of , as the steering speed increases, the target additional deceleration corresponding to the steering speed gradually approaches the prescribed upper limit value D max That is, the target additional deceleration increases as the steering speed increases, and the increase ratio of the increase amount becomes smaller. max The deceleration is set to a level that does not cause the driver to feel control intervention even if deceleration is applied to the vehicle 1 in response to the turning operation (for example, 0.5 m / s 2 ≈ 0.05 G).

[0072] Furthermore, when the steering speed is greater than the threshold value T S1 The threshold T S2 In the above cases, the target additional deceleration is maintained at the upper limit value D max .

[0073] Next, in step S25, the torque reduction amount determination unit 18 sets the rate of change of the additional deceleration to the threshold value R. max (For example 0.5m / s 3 ) below, the additional deceleration in this process is determined.

[0074] Specifically, the rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in step S24 of this process is R max In the following cases, the torque reduction amount determination unit 18 determines the target additional deceleration acquired in step S24 as the additional deceleration in this process.

[0075] On the other hand, the rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in step S24 of this process is greater than R max In the case of the torque reduction amount determination unit 18, the additional deceleration determined in the previous process until the current process is changed by the rate of change R max The changed value is determined as the additional deceleration in this processing.

[0076] Next, in step S26, the torque reduction amount determination unit 18 determines the torque reduction amount based on the current additional deceleration determined in step S25. Specifically, the torque reduction amount determination unit 18 determines the torque reduction amount required to achieve the current additional deceleration based on the current vehicle speed, gear position, road slope, etc. acquired in step S1.

[0077] In addition, in step S22, when the steering speed is not greater than the threshold value T S1 (Threshold T S1 In the case of the following, the process proceeds to step S27, and the torque reduction amount determination unit 18 sets the torque reduction flag to False (pseudo value) indicating that the condition for reducing the torque is not met, and the torque reduction flag indicates whether the condition for reducing the output torque of the engine 4 in order to add deceleration to the vehicle 1 is met.

[0078] After step S26 or S27, the torque reduction amount determination unit 18 ends the torque reduction amount determination process and returns to the main flow.

[0079] Back to Figure 3 After the processing of steps S2 and S3 and the torque reduction amount determination processing of step S4 are performed, in step S5, the final target torque determination unit 20 subtracts the torque reduction amount determined in the torque reduction amount determination processing of step S4 from the basic target torque determined in step S3 to determine the final target torque.

[0080] Next, in step S6, the engine control unit 22 controls the engine 4 to output the final target torque set in step S5. Specifically, the engine control unit 22 determines various state quantities (such as air filling amount, fuel injection amount, intake air temperature, oxygen concentration, etc.) required to achieve the final target torque based on the final target torque set in step S5 and the engine speed, and controls each actuator of each component of the driving engine 4 based on these state quantities. In this case, the engine control unit 22 sets a limit value and a limit range corresponding to the state quantity, sets the control quantity of each actuator so that the state value complies with the limit of the limit value or the limit range, and performs control.

[0081] After step S6 , the PCM 14 ends the engine control process.

[0082] Next, through Figure 6 An example of engine control by the vehicle behavior control device according to the embodiment of the present invention will be described. Figure 6 It is a time chart showing the time change of parameters related to engine control when the vehicle 1 equipped with the vehicle behavior control device according to the embodiment of the present invention turns.

[0083] Figure 6 The diagram (a) of FIG. 1 is a plan view schematically showing a vehicle 1 making a right turn. Figure 6 As shown in the diagram (a), vehicle 1 starts turning right from position A, keeps the steering angle constant from position B to position C, and continues turning right.

[0084] Figure 6 The diagram (b) shows that Figure 6 1 is a line graph showing changes in the steering angle of the vehicle 1 when turning right as shown in the graph (a) of FIG. Figure 6 In the graph (b), the horizontal axis represents time and the vertical axis represents the steering angle.

[0085] If the Figure 6 As shown in the diagram (b), the rightward turn starts at position A, and the rightward steering angle gradually increases by performing the additional wheel turning operation, and the rightward steering angle becomes the maximum at position B. Then, the steering angle remains constant until position C (steering hold).

[0086] Figure 6 The diagram (c) shows that Figure 6 1 is a line graph showing changes in the turning speed of the vehicle 1 when turning right as shown in the graph (a) of FIG. 1 . Figure 6 In the graph (c), the horizontal axis represents time and the vertical axis represents the steering speed.

[0087] The turning speed of the vehicle 1 is expressed by the time derivative of the turning angle of the vehicle 1. That is, Figure 6 As shown in the graph (c) of FIG. 1 , when the rightward turn starts at position A, a rightward turning speed is generated, and the turning speed is kept substantially constant between position A and position B. Then, the rightward turning speed decreases, and when the rightward turning angle becomes the maximum at position B, the turning speed becomes 0. Furthermore, from position B to position C, the turning speed remains 0 while the rightward turning angle is kept.

[0088] Figure 6 Graph (d) is a line graph showing the authenticity value of the torque reduction flag set based on the steering speed. Figure 6 In the graph (d), the horizontal axis represents time, and the vertical axis represents the true or false value of the torque reduction flag.

[0089] like Figure 6 As shown in the diagram (d) of FIG. 1 , before the right turn starts at position A, the torque reduction flag is set to False. Then, after the right turn starts at position A, when the steering speed exceeds the threshold value T S1 When the torque reduction flag changes from False to True, the steering speed decreases as it approaches position B and reaches the threshold value T. S1 When the torque reduction flag changes from True to False.

[0090] Figure 6 Graph (e) is a line graph showing changes in the additional deceleration determined based on the steering speed and the torque reduction flag. Figure 6 In the graph (e), the horizontal axis represents time and the vertical axis represents additional deceleration.

[0091] Reference Figure 4 In step S22, the steering speed is greater than the threshold value T S1 , the torque reduction amount determination unit 18 obtains the target additional deceleration based on the steering speed in step S24. Next, in step S25, the torque reduction amount determination unit 18 determines the target additional deceleration when the increase rate of the additional deceleration is equal to the threshold value R. max The additional deceleration in each processing cycle is determined within the following range.

[0092] like Figure 6 As shown in the graph (e) of , the additional deceleration starts to increase when the torque reduction flag switches from False to True, remains roughly constant between position A and position B, then decreases as the steering speed decreases, and becomes 0 when the torque reduction flag switches from True to False.

[0093] Figure 6 The graph (f) is based on Figure 6 Graph (e) is a line graph showing changes in the torque reduction amount determined by the additional deceleration. Figure 6 In the graph (f), the horizontal axis represents time, and the vertical axis represents the torque reduction amount.

[0094] As described above, the torque reduction amount determination unit 18 determines the torque reduction amount required to achieve the additional deceleration based on the current vehicle speed, gear position, road slope and other parameters. Therefore, when these parameters are constant, the torque reduction amount and Figure 6 The additional deceleration shown in the graph (e) of φ changes in the same manner.

[0095] Figure 6 Graph (g) is a line graph showing changes in the final target torque determined based on the basic target torque and the torque reduction amount. Figure 6 In the graph (g), the horizontal axis represents time and the vertical axis represents torque. Figure 6 The dotted line in the graph (g) represents the basic target torque, and the solid line represents the final target torque.

[0096] As reference Figure 3 As described above, the final target torque determination unit 20 determines the final target torque by subtracting the torque reduction amount determined in the torque reduction amount determination process of step S4 from the basic target torque determined in step S3 .

[0097] That is, Figure 6 As shown in the graph (g) of FIG. 1 , during the period when the torque reduction flag is set to True between position A and position B, the final target torque is reduced by the torque reduction amount from the basic target torque, and the vehicle 1 generates a deceleration corresponding to the torque reduction, so that a load shift occurs to the front wheel 2. As a result, the friction between the front wheel 2 and the road surface increases, and the steering force of the front wheel 2 increases.

[0098] Next, changes in the longitudinal acceleration and the lateral acceleration generated in the vehicle by the control of the vehicle behavior control device according to the embodiment of the present invention will be described using FIG. 7 . Fig. 7A A vehicle equipped with a vehicle behavior control device according to an embodiment of the present invention is shown in FIG. Figure 6 The graph (a) of FIG. 1 is a line graph showing the changes in the longitudinal acceleration and the lateral acceleration from straight driving to the start of a normal circular right turn. Figure 7B Yes Fig. 7A The horizontal axis in FIG7 represents the lateral acceleration (acceleration to the right in the vehicle width direction is positive), and the vertical axis represents the longitudinal acceleration (acceleration in the direction of travel is positive, and deceleration is negative).

[0099] In addition, in Figure 7, the solid line represents the changes in the longitudinal acceleration and lateral acceleration in a vehicle equipped with the vehicle behavior control device according to an embodiment of the present invention, the single-point chain line represents the changes in the longitudinal acceleration and lateral acceleration of a vehicle equipped with the conventional vehicle motion control device described in Patent Document 1, and the dotted line represents the changes in the longitudinal acceleration and lateral acceleration when these control devices are not controlled.

[0100] like Fig. 7A As shown by the single dot-dash line in the figure, in the previous vehicle motion control device described in Patent Document 1, the driver only performs steering for turning so that the acceleration formed by the synthesis of the lateral acceleration and the longitudinal acceleration describes an arc that goes to the left. That is, in order to achieve the vehicle motion that describes an arc that goes to the left while the synthetic acceleration maintains a constant value, which can be achieved by professional drivers, the control device generates a deceleration of the same degree as the lateral acceleration generated in the vehicle according to the driver's steering, and then reduces the deceleration. In order to make the driver feel that the synthetic acceleration changes at a constant value, the magnitude of the deceleration generated by the control sometimes reaches 0.5G. This 0.5G deceleration is the deceleration generated by a strong braking operation in an emergency situation, such as when a standing passenger falls in a bus, and the driver who does not perform an operation for deceleration will feel a strong sense of control intervention.

[0101] On the other hand, Fig. 7AAs shown by the solid line in the middle, the deceleration generated by the control of the vehicle behavior control device according to the embodiment of the present invention is limited to about 0.001G to 0.01G, and the maximum is only 0.05G (the upper limit value D of the target additional deceleration). max ). The deceleration of 0.05G is Fig. 7A The deceleration generated during cornering (ie, the deceleration caused by the cornering drag due to the friction between the road surface and the wheels) indicated by the middle dashed line when the control device is not in effect is substantially the same, so the driver does not notice that the additional deceleration control is in effect.

[0102] In particular, Figure 7B FIG. 1 shows an enlarged view of the PCM 14 of the present embodiment. When the steering speed of the vehicle reaches the threshold value T at the initial stage of turning, S1 When the torque reduction flag is set to True, the output torque of the engine 4 starts to decrease, and the deceleration is rapidly increased in the area where the lateral acceleration is small. As a result, the deceleration increases rapidly compared to the case where the additional deceleration control is not performed. Therefore, when the driver starts the wheel turning operation, the vertical load of the front wheel can be increased immediately to increase the steering force, and the responsiveness and linearity of the vehicle behavior to the wheel turning operation can be improved.

[0103] Next, use Figure 8 to Figure 1 2. The vehicle behavior when a vehicle equipped with the vehicle behavior control device according to the embodiment of the present invention is caused to turn.

[0104] The present inventors reduced the output torque of the engine 4 based on the lateral jerk generated by the steering input at the initial stage of turning, thereby evaluating how the vehicle's behavior changes. To this end, a vehicle equipped with a vehicle behavior control device of the above-mentioned embodiment was driven at a certain speed on a single curve that changes from straight driving to a normal circular turn, and various parameters related to the vehicle's behavior at this time were measured.

[0105] Figure 8 is a line graph showing the measurement results of the vehicle behavior when the vehicle equipped with the vehicle behavior control device according to the present embodiment is caused to turn. Figure 8 The graph (a) is a line graph showing the change of the steering angle of the vehicle. Figure 8 The graph (b) is a line graph showing the change of the lateral jerk generated in the vehicle. Figure 8 Graph (c) is a line graph showing the value of the torque reduction flag set based on the steering speed. Figure 8 The graph (d) is a line graph showing the change of the driving torque for driving the front wheels. Figure 8 The graph (e) is a line graph showing the change in the front-rear jerk produced in the vehicle. Figure 8 The diagram (d) and Figure 8In the graph (e) of FIG. 1 , the solid line indicates the result of the vehicle equipped with the vehicle behavior control device according to the present embodiment, and the dotted line indicates the result of the conventional vehicle not equipped with the vehicle behavior control device.

[0106] If the slip angle of the front wheel increases as the steering angle increases, a steering force is generated by the friction between the road surface and the contact surface of the front wheel. Figure 8 As shown in the graphs (a) and (b) of FIG. 1 , lateral jerk occurs almost simultaneously with the start of the increase in the steering angle. The lateral jerk changes in almost the same manner as the steering speed obtained by time-differentiating the steering angle.

[0107] And, if Figure 8 As shown in the graph (c) of FIG. 1 , during the period of lateral jerk, that is, during the period of steering speed, the torque reduction flag is set to True, such as Figure 8 As shown by the solid line in the graph (d), the driving torque decreases. Figure 6 From the above description, it can be seen that the vehicle behavior control device is operating.

[0108] Furthermore, if the slip angle of the front wheel 2 increases, the friction between the road surface and the contact surface of the front wheel also generates a turning drag. There is a slight delay until the vehicle decelerates due to the turning drag due to the softness of the suspension. Therefore, in a vehicle not equipped with the vehicle behavior control device of this embodiment, if Figure 8 As shown by the dotted line in the graph (e), the jerk of the vehicle's rearward and rearward movement (deceleration jerk) occurs later than the lateral jerk.

[0109] On the other hand, in the vehicle equipped with the vehicle behavior control device of the present embodiment, when the steering speed reaches the threshold value T S1 When the torque reduction flag is set to True, the drive torque reduction starts immediately, so that Figure 8 As shown by the solid line in the graph (e), the deceleration jerk is generated at an earlier timing than the deceleration jerk caused by the turn drag alone, and the deceleration jerk is generated almost simultaneously with the occurrence of the lateral jerk, and the peak of the deceleration jerk appears before the peak of the lateral jerk. Therefore, the vertical load of the front wheel can be increased immediately when the lateral jerk occurs, and the behavior of the vehicle can be controlled with good responsiveness to the driver's steering operation.

[0110] Fig. 9 1 is a line diagram showing how lateral acceleration and longitudinal acceleration are generated during the above-mentioned turning. Fig. 9 In the figure, the horizontal axis represents the acceleration in the vehicle width direction (lateral acceleration), and the vertical axis represents the acceleration in the front-rear direction (front-rear acceleration). Fig. 9 In the figure, the acceleration in the deceleration direction (deceleration) is shown as a negative value.

[0111] As described above, in a vehicle not equipped with the vehicle behavior control device of the present embodiment, when the steering angle starts to increase, the deceleration jerk occurs later than the lateral jerk. Fig. 9 As shown by the middle dotted line, the deceleration does not increase when the lateral acceleration increases (0 to 0.1 G), but if the lateral acceleration increases (ie, the steering force increases), the deceleration increases as the turning drag increases.

[0112] On the other hand, in the vehicle equipped with the vehicle behavior control device of the present embodiment, when the steering speed reaches the threshold value T S1 When the vehicle driving force starts to decrease, the deceleration jerk is generated at an earlier timing than the deceleration jerk caused by the turning drag alone, and the peak of the deceleration jerk appears before the peak of the lateral jerk. Fig. 9 As shown by the solid line in the middle, as the lateral acceleration increases (0 to 0.1G), the deceleration also increases, and the lateral acceleration and deceleration migrate while maintaining a linear relationship. Therefore, not only can the vehicle's behavior be controlled with good responsiveness to the driver's steering operation, but the stability of the vehicle's posture and ride comfort can also be improved.

[0113] Fig.10 is a diagram showing how rolling and pitching occur during the above-mentioned turning. Fig.10 In the figure, the horizontal axis represents the roll angle and the vertical axis represents the pitch angle. Fig.10 In the figure, the pitch angle in the direction where the front of the vehicle sinks is represented by a negative value.

[0114] As described above, in a vehicle not equipped with the vehicle behavior control device of this embodiment, when the steering angle starts to increase, the deceleration jerk occurs later than the lateral jerk, and the deceleration does not increase during the process of increasing lateral acceleration. Fig.10 As shown by the middle dotted line, as the lateral acceleration increases, a load shift occurs in the vehicle width direction of the vehicle, and the pitch angle fluctuates up and down regardless of the increase in the roll angle as the roll angle increases.

[0115] On the other hand, in the vehicle equipped with the vehicle behavior control device of the present embodiment, when the steering speed reaches the threshold value T S1 At the above time, the driving force of the vehicle begins to decrease, and the deceleration jerk occurs almost simultaneously with the occurrence of the lateral jerk. Following the increase in the lateral acceleration, the deceleration also increases, thereby increasing the pitch angle in the direction in which the front of the vehicle sinks in synchronization with the increase in the roll angle.

[0116] FIG. 11 is a schematic diagram showing the vehicle posture by the extension and contraction amount of the suspension of each wheel. Fig.11A is a diagram showing the vehicle posture when parallel rolling occurs. Fig. 11BThe figure shows the vehicle posture when a diagonal roll occurs.

[0117] As described above, in a vehicle not equipped with the vehicle behavior control device of this embodiment, as the lateral acceleration increases, a load shift occurs in the vehicle width direction, and the pitch angle fluctuates up and down regardless of the increase in the roll angle as the roll angle increases. Therefore, at the beginning of a turn, only the roll angle increases, and thus, when the lateral acceleration increases, the pitch angle increases. Fig.11A After the parallel rolling attitude shown, a forward tilt attitude or a backward tilt attitude is generated due to a pitch that occurs independently of the rolling angle.

[0118] On the other hand, in the vehicle equipped with the vehicle behavior control device of the present embodiment, when the steering speed reaches the threshold value T S1 When the vehicle's driving force decreases, the pitch angle increases in the direction of the front of the vehicle sinking, and the rolling angle increases. At the beginning of the turn, the rolling and the pitch of the front of the vehicle sinking occur synchronously, resulting in Fig. 11B Diagonal roll attitude shown.

[0119] As described above, the vehicle behavior control device of the present invention rapidly increases the amount of reduction in driving force in a small area at the initial stage of turning, and when the driver starts turning the wheel, there is a chance to smoothly transfer the vehicle posture to the diagonal rolling posture. As a result, the steering force of the front wheels is increased to improve the responsiveness of the turning behavior, and the driver can clearly perceive that the turning behavior is about to occur and continue.

[0120] FIG. 12 is a line diagram showing how the vertical load of the front wheel changes during the above-mentioned turning. Fig. 12A This is a line graph showing the change in vertical load on the front inner wheel caused by the left-right load shift. Fig. 12B This is a line graph showing changes in the vertical load on the front wheels due to deceleration of the vehicle.

[0121] As described above, in a vehicle that is not equipped with the vehicle behavior control device of the present embodiment, when the steering angle begins to increase, the deceleration does not increase during the process of increasing lateral acceleration, so as shown by the dotted line in Figure 12, as the lateral acceleration increases, the left and right load movement of the front wheels increases linearly. In contrast, during the process of increasing lateral acceleration (0 to 0.1G), there is no front and rear load movement caused by deceleration, so there is no change in the vertical load of the front wheels caused by deceleration. If the lateral acceleration increases, the change in the vertical load of the front wheels caused by deceleration increases due to the increase in deceleration corresponding to the increase in turning drag.

[0122] On the other hand, in the vehicle equipped with the vehicle behavior control device of the present embodiment, when the turning speed becomes equal to or greater than the threshold value TS1, the driving force of the vehicle starts to decrease, and the deceleration also increases with the increase of the lateral acceleration, and the lateral acceleration and the deceleration migrate while maintaining a linear relationship, so as shown by the solid line in FIG. 12, the front-rear load shift caused by deceleration occurs from the increase of the lateral acceleration (0 to 0.1G) in synchronization with the linear increase of the left-right load shift of the front wheels with the increase of the lateral acceleration, and the vertical load change amount of the front wheels increases. As a result, at the initial stage of the vehicle turning, the vertical load of the front wheels is increased, and the vertical load of the front inner wheels caused by the left-right load shift is suppressed, so that the steering force of the front wheels is increased and the responsiveness of the turning behavior is improved.

[0123] Next, another modification example of the embodiment of the present invention will be described.

[0124] In the above-mentioned embodiment, the torque reduction amount determination unit 22 obtains the target additional deceleration based on the steering speed and determines the torque reduction amount based on the target additional deceleration, but the torque reduction amount may also be determined based on the driving state of the vehicle 1 (steering angle, lateral acceleration, yaw angular velocity, slip rate, etc.) other than the operation of the accelerator pedal.

[0125] For example, the torque reduction amount determination unit 22 may determine the torque reduction amount by obtaining the target additional deceleration based on the lateral acceleration input from the acceleration sensor or the lateral jerk obtained by time-differentiating the lateral acceleration.

[0126] Furthermore, in the above-described embodiment, the PCM 14 reduces the output torque of the engine 4 according to the target additional deceleration, thereby causing the vehicle 1 to generate a deceleration jerk in the front-to-rear direction toward the rear, increasing the pitch angle in the direction in which the front portion of the vehicle sinks, and increasing the vertical load on the front wheels. However, a deceleration jerk may be generated by an active engine mounting portion that can movably support the engine 4 up and down, or an active suspension that can control the movement and characteristics of the suspension, thereby increasing the pitch angle in the direction in which the front portion of the vehicle sinks, and increasing the vertical load on the front wheels.

[0127] In addition, in the above-mentioned embodiment, the vehicle 1 equipped with the vehicle behavior control device is equipped with the engine 4 that drives the drive wheels, but the vehicle behavior control device of the present invention can also be applied to a vehicle equipped with a motor that drives the drive wheels by power supplied from a battery or a capacitor. In this case, the PCM 16 controls the motor to reduce the torque according to the steering speed of the vehicle 1.

[0128] Next, effects of the vehicle behavior control device according to the above-described embodiment of the present invention and the modified example of the embodiment of the present invention will be described.

[0129] First, based on the lateral jerk-related amount, when the torque reduction flag is set to True, indicating that the condition for reducing the output torque of the engine 4 is satisfied, the PCM 16 starts to reduce the output torque of the engine 4. Therefore, when the vehicle 1 generates lateral jerk, the output torque of the engine 4 is immediately reduced, thereby increasing the vertical load of the front wheel, and the behavior of the vehicle 1 can be controlled with good responsiveness to the driver's turning operation, thereby not letting the driver feel a sense of intervention, and the responsiveness and linearity of the vehicle behavior to the turning operation can be improved. In addition, the behavior that meets the driver's intention is improved, and a small correction angle is not required, so the stability of the vehicle posture and the ride comfort can also be improved.

[0130] In addition, when the lateral jerk associated amount exceeds a specified threshold, PCM16 sets the torque reduction flag to True. Therefore, when the lateral jerk associated amount is below the threshold, the vehicle 1 can be restrained from overreacting to a slight steering operation. As a result, the vehicle's behavior when driving straight will not cause a sense of disharmony to the driver, and the vehicle's behavior can be controlled to accurately achieve behavior that meets the driver's intentions.

[0131] The lateral jerk-related amount is the turning speed of the vehicle 1 , and the driving force can be reduced immediately after the driver's turning operation starts, thereby controlling the behavior of the vehicle 1 with better responsiveness to the driver's turning operation.

[0132] In addition, when the turning speed is the threshold value T S1 In the above case, the PCM 16 generates a deceleration jerk in the front-rear direction of the vehicle 1. After the driver starts the turning operation, the deceleration jerk can be generated at a timing earlier than the deceleration jerk based on the turning drag alone, and almost simultaneously with the occurrence of the lateral jerk. As a result, in the early stage of the turning of the vehicle 1, the deceleration jerk is immediately generated according to the turning operation to increase the deceleration, thereby increasing the vertical load of the front wheel 2. The behavior of the vehicle 1 can be controlled with good responsiveness and linearity to the driver's turning operation, and the deceleration also increases with the increase of the lateral acceleration in the early stage of the turning. The behavior of the vehicle 1 can be controlled so that the lateral acceleration and the deceleration maintain a linear relationship and migrate. The behavior of the vehicle 1 can be controlled so that the stability of the vehicle posture and the ride comfort can also be improved.

[0133] In addition, when the turning speed is the threshold value T S1At the above time, PCM16 starts to reduce the output torque of engine 4, thereby generating deceleration jerk. Therefore, after the driver starts turning the wheel, the deceleration jerk can be generated with high responsiveness. For the driver's turning operation, the behavior of vehicle 1 can be controlled with better responsiveness, and the behavior of vehicle 1 can also be controlled to further improve the stability of the vehicle posture and ride comfort.

[0134] In addition, when the turning speed is the threshold value T S1 In the above situation, PCM16 generates deceleration jerk so that the peak value of the deceleration jerk appears before the peak value of the lateral jerk. Therefore, at the initial stage of turning of the vehicle 1, the deceleration jerk is immediately generated according to the steering operation, thereby increasing the deceleration. As a result, the vertical load of the front wheel 2 is increased. The behavior of the vehicle 1 can be controlled with better responsiveness to the steering operation of the driver, and the stability of the vehicle posture and the ride comfort can also be improved.

[0135] In addition, when the turning speed is the threshold value T S1 In the above case, the PCM 16 increases the pitch angle in the direction of the front part of the vehicle 1 sinking, so that the front part of the vehicle 1 can be pitched down when rolling occurs after the driver starts the wheel turning operation, thereby generating a diagonal rolling posture at the initial stage of turning of the vehicle 1, increasing the steering force of the front wheel 2 to improve the responsiveness of the turning behavior, and making the driver aware that the turning behavior is generated and continued. Therefore, the behavior of the vehicle 1 can be controlled with good responsiveness and linearity for the driver's wheel turning operation, and the stability of the vehicle posture and the ride comfort can be improved.

[0136] In addition, when the turning speed is the threshold value T S1 When the above is achieved, PCM16 starts to reduce the output torque of the engine 4, thereby increasing the pitch angle in the direction of the front of the vehicle 1 sinking. Therefore, after the driver starts the steering operation, the vehicle 1 is decelerated by reducing the driving force, thereby increasing the pitch angle with high responsiveness. The behavior of the vehicle 1 can be controlled with better responsiveness to the driver's steering operation, and the stability of the vehicle posture and the ride comfort can be further improved.

[0137] In addition, when the turning speed becomes the threshold value T S1 In the above situation, PCM16 increases the pitch angle in the direction of sinking of the front part of the vehicle 1 synchronously with the increase of the roll angle of the vehicle 1, so that at the initial stage of turning of the vehicle 1, a diagonal rolling posture can be reliably generated. As a result, the behavior of the vehicle 1 can be controlled with good responsiveness to the driver's steering operation, and the stability of the vehicle posture and the ride comfort can also be improved.

[0138] In addition, when the turning speed becomes the threshold value T S1In the above case, PCM16 increases the vertical load of the front wheel 2. Therefore, after the driver starts turning the wheel, when the amount of load shifting on the left and right sides of the front wheel 2 increases according to the increase in lateral acceleration, the vertical load of the front wheel 2 can be increased. Thus, in the initial stage of turning of the vehicle 1, the vertical load of the front wheel 2 can be increased and the reduction of the vertical load of the front inner wheel caused by the load shifting on the left and right sides can be suppressed. The steering force of the front wheel 2 can be increased and the responsiveness of the turning behavior can be improved. Thus, the driver will not feel a strong sense of control intervention, and the responsiveness and linearity of the vehicle behavior to the turning operation can be improved. In addition, by accurately realizing the behavior that meets the driver's intention, a small correction angle is not required, so the stability of the vehicle posture and the ride comfort can also be improved.

[0139] In addition, when the turning speed becomes the threshold value T S1 When the above is done, PCM16 starts to reduce the driving force of vehicle 1, thereby increasing the vertical load of front wheel 2. Therefore, after the driver starts turning the wheel, the driving force is reduced to decelerate vehicle 1, and the vertical load of front wheel 2 can be increased with high responsiveness. Therefore, in the early stage of turning, the vertical load of front wheel 2 can be increased rapidly and the reduction of vertical load on the front inner wheel caused by the shift of left and right loads can be suppressed, so that the steering force of the front wheel is increased and the responsiveness of the turning action is improved.

[0140] In addition, when the turning speed becomes the threshold value T S1 In the above situation, PCM16 increases the vertical load of the front wheel 2 synchronously with the left and right load movement of the front wheel 2. Therefore, at the initial stage of turning of the vehicle 1, the vertical load of the front wheel 2 can be reduced and the reduction of the vertical load of the front inner wheel caused by the left and right load movement can be reliably suppressed. As a result, the steering force of the front wheel 2 can be reliably increased and the responsiveness of the turning action can be improved.

Claims

1. A vehicle behavior control device for controlling the behavior of a front-wheel steering vehicle, characterized in that: have: A sensor unit for acquiring various information including a steering angle related to the operating state of the vehicle; a basic target torque determination unit that sets a target acceleration based on the operating state of the vehicle and determines a basic target torque of a power source for achieving the target acceleration, the power source being a power source for driving a driving wheel of the vehicle; a torque reduction amount determination unit that determines a torque reduction amount for adding deceleration to the vehicle based on a steering speed of the vehicle in parallel with setting the target acceleration and determining the basic target torque; a final target torque determination unit that determines a final target torque based on the basic target torque and the torque reduction amount; as well as A power source control unit controls the power source to output the final target torque. The torque reduction amount determination unit calculates the steering speed based on the acquired steering angle; When the steering speed is greater than the first threshold value T S1 In the case of , based on the steering speed, the target additional deceleration to be added to the vehicle is obtained; when the rate of change of the additional deceleration is the threshold value R max The additional deceleration in this process is determined within the following range; and the torque reduction amount is determined based on the additional deceleration determined this time.

2. The vehicle behavior control device according to claim 1, characterized in that: The basic target torque determination unit selects an acceleration characteristic map corresponding to the current vehicle speed and gear position from acceleration characteristic maps defined for various vehicle speeds and various gear positions, and determines the target acceleration corresponding to the current accelerator opening with reference to the selected acceleration characteristic map.

3. The vehicle behavior control device according to claim 1, wherein: The rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in this process is equal to the threshold value R max In the following cases, the torque reduction amount determination unit determines the target additional deceleration obtained in the current process as the additional deceleration in the current process; The rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in this process is greater than the threshold value R max In the case of , the torque reduction amount determination unit determines the value changed according to the change rate from the additional deceleration determined in the previous process to the current process as the additional deceleration in the current process.

4. The vehicle behavior control device according to claim 2, wherein: The rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in this process is equal to the threshold value R max In the following cases, the torque reduction amount determination unit determines the target additional deceleration obtained in the current process as the additional deceleration in the current process; The rate of change from the additional deceleration determined in the previous process to the target additional deceleration obtained in this process is greater than the threshold value R max In the case of , the torque reduction amount determination unit determines the value changed according to the change rate from the additional deceleration determined in the previous process to the current process as the additional deceleration in the current process.

5. The vehicle behavior control device according to any one of claims 1 to 4, characterized in that: When the turning speed is the first threshold value T S1 In the following cases, the corresponding target additional deceleration is 0, and the steering speed exceeds the first threshold value T S1 The more it increases, the more the above target additional deceleration increases, gradually approaching the upper limit of 0.5m / s 2 , when the steering speed is greater than the first threshold T S1 The second threshold T S2 In the above cases, the target additional deceleration is maintained at the upper limit of 0.5 m / s. 2 .

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