JP4556850B2 - Vehicle speed control device - Google Patents

Description

  The present invention relates to a vehicle speed control device that controls the speed of a vehicle.

  Conventionally, a vehicle speed control device that performs control so that the vehicle speed does not exceed a set speed (hereinafter also referred to as “vehicle speed control”) is known. For example, in a vehicle speed limiter that controls the amount of fuel supplied to the engine so that the vehicle speed does not exceed a preset limit value, a method that allows the driver to arbitrarily change the limit value (also called a “variable speed limiter”). Is referred to in Patent Document 1.

JP 2001-225673 A

  Here, from the viewpoint of vehicle running safety, braking / driving force control such as traction control (Traction Control) and vehicle stabilization control has been proposed. In general, traction control is a technique for ensuring a driving force in accordance with a road surface condition by detecting idling of a tire and reducing a driving force of driving wheels. Stabilization control is a technique for ensuring running stability during cornering by detecting an oversteer tendency or understeer tendency during cornering of a vehicle and braking each wheel independently.

  However, the technique described in Patent Document 1 described above sometimes causes unintended engine output fluctuation (hunting) or the like when both vehicle speed control and traction control are executed. Therefore, drivability may be deteriorated.

  The present invention has been made to solve the above-described problems, and provides a vehicle speed control device capable of suppressing problems that may occur by executing both vehicle speed control and braking / driving force control. The purpose is to do.

In one aspect of the present invention, a vehicle speed control device that executes vehicle speed control so that the vehicle speed does not exceed a set speed, a braking / driving force control means that executes braking / driving force control of the vehicle, Estimating means for estimating the vehicle speed used for the vehicle based on the speed of the wheel, and the estimating means is not driven when the braking / driving force control means is in an operating state during execution of the vehicle speed control. The vehicle speed is estimated based on the wheel, and the vehicle speed is estimated based on the drive wheel when the braking / driving force control means is not in an operating state during execution of the vehicle speed control.

Said vehicle speed control apparatus is an apparatus which performs vehicle speed control so that the speed of a vehicle may not exceed the setting speed set, for example by the driver | operator. The braking / driving force control is at least one of control for stabilizing vehicle behavior and traction control. The braking / driving force control is a control whose main purpose is to stabilize the behavior during cornering of the vehicle and to ensure the driving force at the time of slipping, and gives an appropriate braking force to the vehicle. The estimating means estimates the vehicle speed used when executing the vehicle speed control based on the wheel speed (wheel speed). Specifically, the estimating means estimates the vehicle speed based on the non-driving wheels when the braking / driving force control means is in an operating state during execution of the vehicle speed control, and the braking / driving force during execution of the vehicle speed control. When the control means is not in the operating state, the vehicle speed is estimated based on the drive wheels. Accordingly, it is possible to appropriately execute the vehicle speed control and the braking / driving force control while suppressing problems that may occur in the vehicle having both the vehicle speed control function and the braking / driving force control function.

  In a preferred example of the vehicle speed control device, the braking / driving force control means performs traction control. In this case, the vehicle speed control device performs vehicle speed control based on the non-driving wheels when the traction control is in the operating state, and performs vehicle speed control based on the driving wheels when the traction control is not in the operating state. This makes it possible to appropriately suppress unintended engine output fluctuations that occur when vehicle speed control and traction control are performed at the same time, and slipping of drive wheels that occurs when only vehicle speed control is performed.

  In another preferred example of the vehicle speed control device, the braking / driving force control means can perform control for stabilizing vehicle behavior.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Vehicle configuration]
FIG. 1 shows a schematic configuration of a vehicle to which a vehicle speed control device according to the present invention is applied. In FIG. 1, a vehicle 10 includes an engine 1, wheels 2FR, 2FL, 2RR and 2RL, braking devices 3FR, 3FL, 3RR and 3RL, wheel speed sensors 4FR, 4FL, 4RR and 4RL, and a brake hydraulic pressure control unit 5. And a controller 7, an accelerator opening sensor 8, a speed setting unit 9, a longitudinal acceleration sensor 22, a throttle valve 23, and a traction control switch 24. In the following description, the suffixes of wheels, braking devices, wheel speed sensors, etc. are omitted when it is not necessary to distinguish between front and rear wheels and left and right wheels.

  The engine 1 is an internal combustion engine that generates power by exploding an air-fuel mixture in a combustion chamber. The power generated by the engine 1 is transmitted to at least one of the front wheels 2FR and 2FL or the rear wheels 2RR and 2RL via a torque converter, a transmission, a drive shaft, and the like (not shown).

  The brake hydraulic pressure control unit 5 controls the braking force of each braking device 3 provided on each wheel 2, and operates based on a control signal 15 supplied from the controller 7. The brake hydraulic pressure control unit 5 includes a master cylinder (not shown) and a transmission system, and hydraulically controls each braking device 3 according to an operation amount of a brake pedal (not shown). Further, the brake hydraulic pressure control unit 5 has a lock prevention function such as ABS (Anti-lock Brake System), and can control the operation amount of each brake device 3 irrespective of the operation amount of the brake pedal. .

  The braking devices 3FR, 3FL, 3RR, and 3RL are devices that directly brake the wheels 2FR, 2FL, 2RR, and 2RL, respectively, and are based on control signals 13FR, 13FL, 13RR, and 13RL supplied from the brake hydraulic pressure control unit 5. The braking force is applied to each wheel 2FR, 2FL, 2RR, and 2RL.

  Wheel speed sensors 4FR, 4FL, 4RR, and 4RL are provided on the wheels 2FR, 2RL, 2RR, and 2RL, respectively, detect the wheel speed of each wheel individually, and send detection signals 14FR, 14FL, 14RR, and 14RL to the controller 7. Supply.

  The accelerator opening sensor 8 detects an operation amount by a driver of an accelerator pedal provided in the vehicle 10 and supplies it to the controller 7 as a detection signal 18. Further, the longitudinal acceleration sensor 22 detects acceleration in the longitudinal direction of the vehicle (lateral direction in FIG. 1) and supplies the detected signal 19 to the controller 7. The throttle valve 23 is a valve that adjusts the amount of intake air supplied to the engine 1. The throttle valve 23 has its opening degree (throttle opening degree) controlled by a control signal 11 supplied from the controller 7.

  The speed setting unit 9 is an input unit that is operated by the driver in order to input a setting speed and an on / off switching instruction for vehicle speed control in the vehicle 10. The vehicle speed control in the present embodiment is also called a variable speed limit, a vehicle speed limit, or the like, and controls the vehicle so that the vehicle speed does not exceed a set speed. For example, when the driver is traveling at a predetermined speed, the vehicle speed at that time is set to the set speed by pressing an operation switch constituting the speed setting unit 9 or the like. The traction control switch 24 is an input unit that is operated by the driver in order to input a traction control on / off switching instruction.

  The controller 7 includes a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like (not shown). Specifically, the controller 7 executes vehicle speed control and traction control based on the outputs from the various sensors and switches described above. Specifically, the controller 7 compares the vehicle speed (the wheel speed of the driving wheel or the wheel speed of the non-driving wheel) with the set speed, and performs vehicle speed control for reducing the vehicle speed when the vehicle speed exceeds the set speed. In this case, the controller 7 performs vehicle speed control so that the vehicle speed is substantially maintained at the set speed. Further, the controller 7 determines whether or not the driving wheel is slipping by comparing the wheel speed of the driving wheel and the wheel speed of the non-driving wheel, and when it is determined that the driving wheel slips, Traction control for adjusting the braking force of the wheels 2 is executed.

  Specifically, the controller 7 controls the throttle opening by supplying the control signal 11 to the throttle valve 23 based on the detection signal 14 from the wheel speed sensor 4 of the driving wheel and the non-driving wheel. Thus, the engine output is adjusted, and vehicle speed control and traction control are executed. More specifically, the required throttle opening by the vehicle speed control and the required throttle opening by the traction control are obtained, and the smallest one of the two required throttle opening and the driver required throttle opening is finally selected. Determined as throttle opening. Thus, the controller 7 functions as a vehicle speed control device in the present invention and operates as a braking / driving force control means.

  Below, the vehicle speed control which concerns on this embodiment is demonstrated.

[Vehicle speed control method]
Next, vehicle speed control according to the present embodiment will be described. In the present embodiment, the vehicle speed used for the vehicle speed control (the speed used when compared with the set speed) is calculated based on whether the traction control is on or not. Change and use. That is, in this embodiment, the vehicle speed control is executed by changing the wheel for obtaining the vehicle speed according to the operation state of the traction control without fixing the wheel for obtaining the vehicle speed. Specifically, when the traction control is on, the wheel speed of the non-driving wheel is used as the vehicle speed used for the vehicle speed control, and when the traction control is off, the wheel speed of the driving wheel is used as the vehicle speed used for the vehicle speed control. Use.

  Specifically, the controller 7 estimates the vehicle speed used when executing the vehicle speed control based on the wheel speed. Specifically, the controller 7 estimates the vehicle speed based on the non-driving wheels when the traction control is in the operating state, and estimates the vehicle speed based on the driving wheels when the traction control is not in the operating state. Further, the controller 7 uses the average wheel speed of the drive wheels (hereinafter referred to as “drive wheel average speed”, expressed as “Vdr”) as the wheel speed of the drive wheels, and as the wheel speed of the non-drive wheels. The average wheel speed of non-driving wheels (hereinafter referred to as “non-driving wheel average speed” and expressed as “Vndr”) is used. Thus, the controller 7 operates as an estimation unit of the present invention.

  In this way, the vehicle speed used for the vehicle speed control is changed in a vehicle having the functions of the vehicle speed control and the traction control, and the vehicle speed control is executed using the same wheel speed without considering the on / off of the traction control. This is because a problem may occur. Specifically, when the vehicle speed control is performed using the wheel speed of the non-driven wheels when the traction control is on, an unintended engine output fluctuation may occur. In addition, when the vehicle speed control is performed using the wheel speed of the drive wheel when the traction control is off, the drive wheel may continue to slip for a long time.

  Here, a problem that occurs when the wheel speed used for the vehicle speed control is selected without considering the on / off of the traction control will be specifically described with reference to FIGS.

  FIG. 2 is a diagram for explaining a problem that occurs when the vehicle speed control is performed using the drive wheel average speed Vdr when the traction control is on (specifically, when the traction control is executed). It is. 2A and 2B, the horizontal axis indicates time, the vertical axis in FIG. 2A indicates the throttle opening, and the vertical axis in FIG. 2B indicates the vehicle speed. Yes. In the example of FIG. 2, the controller 7 is assumed to continue the vehicle speed control and the traction control in the on state.

  The meanings of variables used in FIG. 2 are as follows.

Vasl: set speed Vdr: driving wheel average speed Vndr: non-driving wheel average speed Tasl: required throttle opening by vehicle speed control Ttrc: required throttle opening by traction control Tdvr: driver required throttle opening (= accelerator opening)
Tfin: last selected throttle opening Tmax: maximum throttle opening (= throttle valve fully open)
Tmin: Minimum throttle opening (= Throttle valve fully closed)
First, when the driver depresses the accelerator pedal, the driver-requested throttle opening Tdvr increases. Then, the controller 7 executes vehicle speed control at time t10 and executes traction control at time t11. As the driver required throttle opening degree Tdvr increases as described above, the driving wheel average speed Vdr increases to reach the set speed Vasl, and the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr is large. (Time t12). Therefore, the controller 7 lowers the required throttle opening degree Tasl and lowers the required throttle opening degree Ttrc by traction control. In this case, the required throttle opening degree Tasl by vehicle speed control is selected as the final selected throttle opening degree Tfin. Specifically, a throttle opening that is considerably smaller than the required throttle opening Ttrc by traction control is determined.

  At the time t13, the driving wheel average speed Vdr is substantially lower than the set speed Vasl and is substantially the same as the non-driving wheel average speed Vndr. Therefore, the controller 7 greatly increases the required throttle opening degree Tasl by the vehicle speed control so that the driving wheel average speed Vdr approaches the set speed Vasl. As a result, the final selected throttle opening Tfin is also greatly increased. Thereafter, the drive wheel average speed Vdr reaches the set speed Vasl, and the difference between the drive wheel average speed Vdr and the non-drive wheel average speed Vndr increases. Therefore, the controller 7 again greatly reduces the final selected throttle opening Tfin (time t14).

  As described above, when the vehicle speed control is performed using the drive wheel average speed Vdr during the traction control, the drive wheel average speed Vdr and the final selected throttle opening Tfin are repeatedly increased and decreased. Recognize. Such a phenomenon occurs because of an output increase request due to vehicle speed control performed to increase the drive wheel average speed Vdr to the set speed Vasl, and traction control for suppressing slip caused by the output increase request due to this vehicle speed control. This is because the output reduction request is repeatedly performed. In other words, the vehicle speed control and the traction control suppress the effects caused by the mutual control (a decrease in the driving wheel average speed Vdr and an increase in the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr). To work. When such increase and decrease of the final selected throttle opening Tfin are repeatedly generated, the engine output may fluctuate greatly (hunting occurs), and drivability may be deteriorated.

  FIG. 3 is a diagram for explaining a problem that occurs when the vehicle speed control is performed using the non-driving wheel average vehicle speed Vndr when the traction control is off (that is, when the traction control is not executed). 3 (a) and 3 (b), the horizontal axis indicates time, the vertical axis in FIG. 3 (a) indicates the throttle opening, and the vertical axis in FIG. 3 (b) indicates the vehicle speed. Yes. In the example of FIG. 3, the controller 7 continues the vehicle speed control in the on state and continues the traction control in the off state. Further, the meanings of variables used in FIG. 3 are the same as those shown in FIG.

  First, at time t21, when the driver depresses the accelerator pedal, the driver required throttle opening degree Tdvr increases and the drive wheel average speed Vdr increases greatly. The driving wheel average speed Vdr greatly exceeds the set speed Vasl. However, the non-driving wheel average speed Vndr does not increase immediately but gradually increases. In this case, since the non-driving wheel average speed Vndr is far away from the set speed Vas, the controller 7 continues to maintain the required throttle opening degree Tasl by the vehicle speed control at the maximum throttle opening degree Tmax without executing the vehicle speed control. . That is, although the drive wheel average speed Vdr greatly exceeds the set speed Vasl, it is determined whether the vehicle speed control should be executed based on the non-drive wheel average speed Vndr. The execution of is not started. Therefore, for a while, the driver-requested throttle opening Tdvr continues to be determined as the final selected throttle opening Tfin.

  At time t22, since the non-driving wheel average speed Vndr approaches the set speed Vasl, the controller 7 starts executing the vehicle speed control and decreases the required throttle opening degree Tasl by the vehicle speed control. Thus, when a certain amount of time has elapsed from time t22, the required throttle opening degree Tasl by vehicle speed control is selected as the final selected throttle opening degree Tfin. From this point, the drive wheel average speed Vdr finally starts to decrease.

  As described above, when the vehicle speed control is performed using the non-driving wheel average speed Vndr when the traction control is off, the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr is large. It can be seen that the state in which the drive wheel slips continues for a long time. This is because the start of the vehicle speed control is delayed because the increase in the non-driving wheel average speed Vndr is slow.

  FIG. 4 is a diagram showing a flowchart of the vehicle speed control according to the present embodiment. This process is mainly executed by the controller 7 using the outputs of the wheel speed sensors 4, the accelerator opening sensor 8, the speed setting unit 9, and the like. Further, the process shown in FIG. 4 is repeatedly executed at predetermined time intervals while the vehicle is traveling.

  First, in step S101, the controller 7 determines whether vehicle speed control is on. Specifically, the controller 7 makes a determination based on the output of the speed setting unit 9. If the vehicle speed control is on (step S101; Yes), the process proceeds to step S102. If the vehicle speed control is off (step S101; No), the process exits the flow.

  In step S102, the controller 7 determines whether or not the traction control is off. Specifically, the controller 7 makes a determination based on the output of the traction control switch 24. If the traction control is off (step S102; Yes), the process proceeds to step S103. In step S103, the controller 7 sets the vehicle speed used for vehicle speed control (hereinafter referred to as “vehicle speed for vehicle speed control” and expressed as “VX”) to the drive wheel average speed Vdr. This is to suppress engine output fluctuations that may occur when traction control is on. Then, the process exits the flow.

  On the other hand, when the traction control is on (step S102; No), the process proceeds to step S104. In step S104, the controller 7 sets the vehicle speed VX for vehicle speed control to the non-drive wheel average speed Vndr. This is to suppress drive wheel slip that may occur when traction control is off. When the traction control is on, the vehicle speed control vehicle speed VX is set to the non-driven wheel average speed Vndr even when the traction control is not being executed. When the above process ends, the process exits the flow.

  As described above, by executing the vehicle speed control according to the present embodiment, it is possible to appropriately prevent unintended engine output fluctuations and long-lasting drive wheel slips that may occur in a vehicle having vehicle speed control and traction control functions. Can be suppressed.

  Hereinafter, examples of the above-described vehicle speed control will be described.

(Vehicle speed control according to the embodiment)
FIG. 5 shows a flowchart of the vehicle speed control according to the embodiment of the present invention, and FIGS. 6A and 6B show examples of maps used in this vehicle speed control. This process is mainly executed by the controller 7 using the outputs of the wheel speed sensors 4, the accelerator opening sensor 8, the speed setting unit 9, and the like. Further, the process shown in FIG. 5 is repeatedly executed at predetermined time intervals while the vehicle is traveling. Further, the meaning of variables used in the flowchart is the same as that shown in FIG.

  First, in step S201, the controller 7 determines whether or not the vehicle speed control is on. Specifically, the controller 7 makes a determination based on the output of the speed setting unit 9. If the vehicle speed control is on (step S201; Yes), the process proceeds to step S203. If the vehicle speed control is off (step S201; No), the process proceeds to step S202.

  In step S202, the controller 7 determines the minimum value of the driver requested throttle opening Tdvr and the requested throttle opening Ttrc by traction control as the final selected throttle opening Tfin. In this case, since the vehicle speed control is off, the final selected throttle opening degree Tasl by the vehicle speed control is not used. When the drive wheel slips, the vehicle speed is reduced by controlling the throttle valve 23 to the determined final selected throttle opening Tfin. When the process of step S202 ends, the process exits the flow.

  In step S203, the controller 7 determines whether or not the traction control is off. Specifically, the controller 7 makes a determination based on the output of the traction control switch 24. If the traction control is off (step S203; Yes), the process proceeds to step S204.

  In Step S204, the controller 7 sets the vehicle speed control vehicle speed VX to the drive wheel average speed Vdr. This is to suppress drive wheel slip that may occur when traction control is off. Then, the process proceeds to step S205.

  In step S205, the controller 7 sets the required throttle opening degree Ttrc by traction control to the maximum throttle opening degree Tmax. That is, a request is made to fully open the throttle opening. This is to prevent the requested throttle opening degree Ttrc from being selected as the final selected throttle opening degree Tfin in step S207 described later. That is, in this situation, since the traction control is not executed, the requested throttle opening degree Ttrc should not be selected as the final selected throttle opening degree Tfin. When the above process ends, the process proceeds to step S206.

  In step S206, the controller 7 refers to the map 1 (function f1) shown in FIG. 6A, and calculates the required throttle opening degree Tasl by vehicle speed control based on the vehicle speed control set speed Vasl and the vehicle speed control vehicle speed VX. decide. As shown in FIG. 6A, in the map 1, the horizontal axis indicates the difference between the set speed Vasl and the vehicle speed control vehicle speed VX, and the vertical axis indicates the required throttle opening degree Tasl by vehicle speed control. Since the set speed is set as a limit speed, the required throttle opening degree Tasl increases as the vehicle speed control vehicle speed VX is smaller than the set speed Vasl, and the vehicle speed control vehicle speed VX is controlled to approach the set speed Vasl. Then, the process proceeds to step S207.

  In step S207, the controller 7 determines the minimum value among the driver requested throttle opening Tdvr, the requested throttle opening Tasl by vehicle speed control, and the requested throttle opening Ttrc by traction control as the final selected throttle opening Tfin. Thereby, the vehicle speed is reduced. When the above process ends, the process exits the flow.

  On the other hand, when the traction control is on in step S203 (step S203; No), the process proceeds to step S208. In step S208, the controller 7 sets the vehicle speed control vehicle speed VX to the non-driving wheel average speed Vndr. This is to suppress engine output fluctuations that may occur when traction control is on. Then, the process proceeds to step S209.

  In step S209, the controller 7 determines whether or not traction control is currently being executed. When the traction control is not executed (step S209; No), the process proceeds to step S205. In this case, since the traction control is not executed, the required throttle opening degree Ttrc by the traction control is set to the maximum throttle opening degree Tmax (the process of step S205). Therefore, in step S207, the requested throttle opening degree Ttrc is not selected as the final selected throttle opening degree Tfin. On the other hand, when the traction control is being executed (step S209; Yes), the process proceeds to step S210.

  In step S210, the controller 7 refers to the map 2 (function f2) shown in FIG. 6B, and calculates the required throttle opening degree Ttrc by traction control based on the driving wheel average speed Vdr and the non-driving wheel average speed Vndr. decide. As shown in FIG. 6B, in the map 2, the horizontal axis indicates the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr, and the vertical axis indicates the required throttle opening degree Ttrc by traction control. As described above, the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr corresponds to the slip amount. Therefore, the map 2 is a map that limits the speed by decreasing the throttle opening as the slip amount increases. ing. When the above process ends, the process proceeds to step S206.

  In this case, the controller 7 obtains the required throttle opening degree Tasl by the vehicle speed control based on the map 1 (step S206), the driver required throttle opening degree Tdvr, the required throttle opening degree Tasl by the vehicle speed control, and the required throttle opening degree by the traction control. The minimum value of the opening degree Ttrc is determined as the final selected throttle opening degree Tfin (step S207). Thereby, the vehicle speed is reduced. When the above process ends, the process exits the flow.

  7 and 8 show execution examples of vehicle speed control according to the embodiment of the present invention.

  FIG. 7 shows an execution example when the vehicle speed control is performed using the non-driving wheel average speed Vndr when the traction control is on. The horizontal axes in FIGS. 7A and 7B indicate time, the vertical axis in FIG. 7A indicates the throttle opening, and the vertical axis in FIG. 7B indicates the vehicle speed. Yes.

  First, when the driver depresses the accelerator pedal, the driver-requested throttle opening Tdvr increases. And the controller 7 performs traction control at the time t31. As the driver required throttle opening degree Tdvr increases as described above, the driving wheel average speed Vdr increases, and the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr increases. Therefore, the controller 7 reduces the required throttle opening degree Ttrc by traction control. At this time, the controller 7 does not execute the vehicle speed control because the non-driving wheel average speed Vndr that is referred to when performing the vehicle speed control is away from the set speed Vasl. In this case, the controller 7 continues to maintain the required throttle opening degree Tasl by the vehicle speed control at the maximum throttle opening degree Tmax. Therefore, the required throttle opening degree Ttrc by traction control is determined as the final selected throttle opening degree Tfin. By using the determined final selected throttle opening degree Tfin, the driving wheel average speed Vdr decreases, and the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr becomes small (time t32).

  Next, since the non-driving wheel average speed Vndr approaches the set speed Vasl at time t33, the controller 7 starts vehicle speed control. At time t33, the difference between the driving wheel average speed Vdr and the non-driving wheel average speed Vndr is not so large, so that the required throttle opening degree Ttrc by the traction control is not greatly reduced. Further, since the difference between the non-driven wheel average speed Vndr and the set speed Vasl is not so large, the required throttle opening degree Tasl by the vehicle speed control is not rapidly reduced. Therefore, at time t33, the final selected throttle opening Tfin that is selected is not greatly reduced.

  Therefore, after time t33, the final selected throttle opening Tfin does not vary greatly, the difference between the drive wheel average speed Vdr and the non-drive wheel average speed Vndr is reduced, and the drive wheel average speed Vdr and the non-drive wheel average speed are reduced. The speed Vndr approaches the set speed Vasl. That is, it can be said that the fluctuation range of the throttle opening is small compared to the case where the driving wheel average speed Vdr is used when the traction control is on (see FIG. 2). At time t34, the controller 7 ends the traction control because there is no difference between the drive wheel average speed Vdr and the non-drive wheel average speed Vndr. Thereafter, the driving wheel average speed Vdr and the non-driving wheel average speed Vndr are maintained at a substantially constant speed equal to or lower than the set speed Vasl.

  FIG. 8 shows an execution example when the vehicle speed control is performed using the drive wheel average vehicle speed Vdr when the traction control is off. 8 (a) and 8 (b), the horizontal axis indicates time, the vertical axis in FIG. 8 (a) indicates the throttle opening, and the vertical axis in FIG. 8 (b) indicates the vehicle speed. Yes.

  First, when the driver depresses the accelerator pedal, the driver-requested throttle opening Tdvr increases. And the controller 7 performs vehicle speed control at the time t41. As the driver required throttle opening degree Tdvr increases, the drive wheel average speed Vdr increases, so the controller 7 decreases the required throttle opening degree Tasl by vehicle speed control. In this case, the driver requested throttle opening Tdvr is determined as the final selected throttle opening Tfin until time t42, but the required throttle opening Tasl by vehicle speed control is determined as the final selected throttle opening Tfin after time t42. . As a result, the final selected throttle opening Tfin starts to decrease from time t42, and the drive wheel average vehicle speed Vdr begins to decrease. Thereafter, the drive wheel average vehicle speed Vdr is maintained at a substantially constant speed equal to or lower than the set speed Vasl.

  On the other hand, the non-driving wheel average speed Vndr gradually increases toward the set speed Vasl due to the increase in the driver-requested throttle opening Tdvr. In this case, the difference between the drive wheel average vehicle speed Vdr and the non-drive wheel average vehicle speed Vndr is not so large. Therefore, the vehicle speed using the non-drive wheel average vehicle speed Vndr shown in FIG. Compared with the example in the case of control, it can be said that almost no slip occurs.

  As described above, according to the vehicle speed control according to the embodiment of the present invention, it is possible to appropriately execute the vehicle speed control and the traction control while suppressing unintended engine output fluctuation and slipping of the drive wheel that continues for a long time. it can.

[Modification]
In the above-described embodiment, the case where the traction control is executed during the vehicle speed control has been described. However, the present invention can be applied to a case where vehicle behavior stabilization control such as VSC (Vehicle Stability Control) control is executed during the vehicle speed control. Can be applied as well. The vehicle behavior stabilization control is a technology that ensures traveling stability during cornering by detecting an oversteer tendency or understeer tendency during cornering of the vehicle and braking each wheel independently. In a typical example, the force generated in the vehicle during cornering is detected using a yaw rate sensor, longitudinal and lateral acceleration sensors, etc. in addition to the wheel speed sensor of four wheels, so that the behavior of the vehicle is stabilized. Appropriate braking force is applied to each wheel independently. In the present invention, the concept including the control for stabilizing the vehicle behavior and the traction control is called “braking driving force control”.

  FIG. 9 shows a flowchart of the vehicle speed control according to the modified example, and FIG. 10 shows an example of a map used in the vehicle speed control according to the modified example. The vehicle speed control according to the modified example is different from the vehicle speed control according to the above-described embodiment (see FIG. 5) in that VSC control is performed instead of traction control. This process is mainly executed by the controller 7 using outputs from the wheel speed sensors 4, the accelerator opening sensor 8, the speed setting unit 9, the yaw rate sensor (not shown), and the like. Further, the process shown in FIG. 9 is repeatedly executed at predetermined time intervals while the vehicle is traveling.

  In addition, the meaning of the variable etc. which are newly used in FIG. 9 is as follows.

Tvsc: Required throttle opening by VSC control Yr: Yaw rate Ystr: Yaw rate calculated from the steering angle The yaw rate Ystr calculated from the steering angle is a stability factor Kh, a steering angle θ, a steering gear ratio n, a wheelbase L Is represented by the formula (1).

Ystr = 1 / (1 + Kh × VX ² ) × (θ / n × L × VX) Equation (1)
First, in step S301, the controller 7 determines whether or not the vehicle speed control is on. If the vehicle speed control is on (step S301; Yes), the process proceeds to step S303, and the vehicle speed control is off. If so (step S301; No), the process proceeds to step S302.

  In step S302, the controller 7 determines the minimum value among the driver requested throttle opening Tdvr and the requested throttle opening Tvsc by VSC control as the final selected throttle opening Tfin. When the behavior of the vehicle is unstable, the vehicle speed is reduced by controlling the throttle valve 23 to the determined final selected throttle opening Tfin. When the process of step S302 ends, the process exits the flow.

  In step S303, the controller 7 determines whether or not the VSC control is off. If the VSC control is off (step S303; Yes), the process proceeds to step S304. In step S304, the controller 7 sets the vehicle speed VX for vehicle speed control to the drive wheel average speed Vdr. Then, the process proceeds to step S305.

  In step S305, the controller 7 sets the required throttle opening degree Tvsc by the VSC control to the maximum throttle opening degree Tmax. That is, a request is made to fully open the throttle opening. This is to prevent the requested throttle opening degree Tvsc from being selected as the final selected throttle opening degree Tfin in step S307 described later. Then, the process proceeds to step S306.

  In step S306, the controller 7 refers to the map 1 (function f1) shown in FIG. 10A, and calculates the required throttle opening degree Tasl by the vehicle speed control based on the vehicle speed control set speed Vasl and the vehicle speed control vehicle speed VX. decide. Then, the process proceeds to step S307.

  In step S307, the controller 7 determines the minimum value among the driver requested throttle opening Tdvr, the requested throttle opening Tasl by vehicle speed control, and the requested throttle opening Tvsc by VSC control as the final selected throttle opening Tfin. Thereby, the vehicle speed is reduced. When the above process ends, the process exits the flow.

  On the other hand, when the VSC control is on in step S303 (step S303; No), the process proceeds to step S308. In step S308, the controller 7 sets the vehicle speed control vehicle speed VX to the non-driving wheel average speed Vndr. Then, the process proceeds to step S309.

  In step S309, the controller 7 determines whether or not the VSC control is currently being executed. When the VSC control is not executed (step S309; No), the process proceeds to step S305. In this case, since the VSC control is not executed, the required throttle opening degree Tvsc based on the VSC control is set to the maximum throttle opening degree Tmax (processing in step S305). On the other hand, when the VSC control is being executed (step S309; Yes), the process proceeds to step S310.

  In step S310, the controller 7 refers to the map 3 (function f3) shown in FIG. 10, and calculates the required throttle opening degree Tvsc by the VSC control based on the detected yaw rate Yr and the yaw rate Ystr calculated from the steering angle. decide. As shown in FIG. 10, in the map 3, the horizontal axis indicates the difference (absolute value) between the detected yaw rate Yr and the yaw rate Ystr calculated from the steering angle, and the vertical axis indicates the required throttle opening Tvsc by VSC control. Yes. Map 2 is a map that limits the speed by decreasing the required throttle opening Tvsc as the absolute value of the difference between the yaw rate Yr and the yaw rate Ystr increases. Then, the process proceeds to step S306.

  In this case, the controller 7 obtains the required throttle opening degree Tasl by the vehicle speed control based on the map 1 (step S306), the driver required throttle opening degree Tdvr, the required throttle opening degree Tasl by the vehicle speed control, and the required throttle degree by the VSC control. The minimum value of the opening Tvsc is determined as the final selected throttle opening Tfin (step S307). Thereby, the vehicle speed is reduced. When the above process ends, the process exits the flow.

  As described above, by executing the vehicle speed control according to the modified example, the vehicle speed control and the VSC control are appropriately executed while suppressing problems that may occur in the vehicle having both the vehicle speed control and the VSC control functions. Can do.

  In the above description, the embodiment has been described in which the vehicle speed control vehicle speed is changed based on the on / off state of the traction control switch 24 (see step S203 in FIG. 5 and step S303 in FIG. 9). Instead of turning on / off, the vehicle speed VX for vehicle speed control may be changed based on an abnormality of a sensor in the vehicle 10 or an actuator of a brake.

  Furthermore, the present invention is not limited to executing vehicle speed control and traction control by controlling the throttle opening. In another embodiment, vehicle speed control and traction control can be executed by controlling the brake hydraulic pressure control unit 5 and the braking device 3 and controlling the fuel injection amount instead of the throttle opening.

1 shows a schematic configuration of a vehicle to which a vehicle speed control device according to the present invention is applied. It is a figure for demonstrating the malfunction which generate | occur | produces when traction control is ON. It is a figure for demonstrating the malfunction which arises when traction control is OFF. It is a flowchart of the vehicle speed control which concerns on embodiment of this invention. It is a flowchart of the vehicle speed control which concerns on the Example of this invention. It is an example of the map used by the vehicle speed control which concerns on an Example. The execution example of the vehicle speed control which concerns on the Example of this invention is shown. The execution example of the vehicle speed control which concerns on the Example of this invention is shown. It is a flowchart of the vehicle speed control which concerns on a modification. It is an example of the map used by the vehicle speed control which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Wheel 3 Braking device 4 Wheel speed sensor 5 Brake hydraulic pressure control part 7 Controller 8 Accelerator opening degree sensor 9 Speed setting part 10 Vehicle 23 Throttle valve

Claims (3)

A vehicle speed control device that executes vehicle speed control so that the vehicle speed does not exceed a set speed,
Braking / driving force control means for executing braking / driving force control of the vehicle;
An estimation means for estimating a vehicle speed to be used when executing the vehicle speed control based on a wheel speed;
The estimation means includes
During execution of the vehicle speed control, when the braking / driving force control means is in an operating state, the vehicle speed is estimated based on non-driving wheels,
A vehicle speed control device that estimates the vehicle speed based on drive wheels when the braking / driving force control means is not in an operating state during execution of the vehicle speed control. The vehicle speed control apparatus according to claim 1 , wherein the braking / driving force control means performs traction control. The vehicle speed control device according to claim 1 , wherein the braking / driving force control means performs control for stabilizing vehicle behavior.

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