JP4175207B2 - Vehicle and vehicle control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate a torque shock when a slip generated while securing running stability of a vehicle is suppressed. <P>SOLUTION: A method for controlling the vehicle includes a step of limiting a request torque requested for a driver when a slip occurs by using a torque upper limit value Tmax. Then, when the vehicle runs during predetermined steering or runs on a slope road at an extremely low speed, the vehicle judges an unstable state, and regulates a torque upper limit value Tmax by preceding rapid converging of the slip to alleviate the torque shock when the request torque is limited (S258). Meanwhile, the method includes a step of judging that the vehicle is a stable state when the vehicle runs at a low vehicle speed without steering on a flat road, and regulates a torque upper limit value Tmax by preceding the alleviation of the torque shock when the request torque is limited (S262). Thus, the torque shock when the slip generated by assuring running stability of the vehicle is suppressed can be reduced. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle and a vehicle control method, and more particularly, to a vehicle including an electric motor capable of outputting power to a drive shaft connected to drive wheels.
[0002]
[Prior art]
Conventionally, as this type of vehicle, there has been proposed a vehicle that estimates the road surface gradient and suppresses the output of the engine when excessive slip of the drive wheels occurs (see Patent Document 1). In this vehicle, when the upslope is estimated when an excess slip occurs, the initial control torque necessary to converge the excess slip is corrected in the direction to increase, and the engine is driven to control, so this is necessary when the excess slip occurs. As described above, the initial control torque is prevented from being lowered, and the acceleration performance of the vehicle when starting uphill is ensured.
[0003]
[Patent Document 1]
JP-A-7-77080
[0004]
[Problems to be solved by the invention]
However, in such a vehicle, when a motor having a quick output response in control as compared with the engine is used as a power source for traveling, a shock may occur due to suppression of output when excessive slip occurs. On the other hand, when a slip occurs when the vehicle is unstable, it is necessary to quickly converge the slip to ensure the running stability of the vehicle.
[0005]
One object of the vehicle of the present invention is to solve such problems and suppress a shock when limiting the torque output to the drive shaft when a slip occurs. Another object of the vehicle of the present invention is to suppress a shock when limiting the torque output to the drive shaft when slip occurs while ensuring the running stability of the vehicle.
[0006]
[Means for solving the problems and their functions and effects]
The vehicle of the present invention employs the following means in order to achieve at least a part of the above-described object.
[0007]
The vehicle of the present invention
A vehicle including an electric motor capable of outputting power to a drive shaft connected to a drive wheel,
Slip detecting means for detecting slip due to idling of the drive wheel;
Traveling state detecting means for detecting the traveling state of the vehicle;
As a degree of restraining the torque output to the drive shaft from being suddenly limited based on the running state of the vehicle detected by the running state detecting unit when slip is detected by the slip detecting unit. A suppression degree setting means for setting a sudden limit suppression degree of
Control means for controlling the drive of the electric motor so that the torque output to the drive shaft is limited using the set sudden limit suppression degree;
It is a summary to provide.
[0008]
In the vehicle according to the present invention, a sudden limit suppression degree is set as a degree at which the torque output to the drive shaft is suppressed from being rapidly limited based on the running state of the vehicle when slip is detected. The electric motor capable of outputting power to the drive shaft is driven and controlled so that the torque output to the drive shaft is limited using the set sudden limit suppression degree. Therefore, the slip can be converged while suppressing a shock at the time of limiting the torque output to the drive shaft with the detection of the slip to a degree based on the running state of the vehicle. Here, the “electric motor” may be a single electric motor common to the left and right wheels as drive wheels.
[0009]
In such a vehicle of the present invention, the suppression degree setting means may be a means for setting the sudden limit suppression degree so that the detected traveling state of the vehicle tends to become unstable. . In this way, when the vehicle tends to be relatively unstable, the degree of suppression of the sudden limit of the torque output to the drive shaft can be reduced, and the slip can be quickly converged to ensure the running stability of the vehicle. When the torque tends to be relatively stable, it is possible to reduce the shock by increasing the degree of suppression of the rapid limitation of the torque output to the drive shaft.
[0010]
In the vehicle of the present invention, the traveling state detecting means includes means for detecting a steering amount of the vehicle, and the suppression degree setting means is based on the detected steering amount of the vehicle. It is also possible to use a means for setting the sudden limit suppression degree. In this aspect of the vehicle of the present invention, the traveling state detection means includes means for detecting the vehicle speed of the vehicle, and the suppression degree setting means includes the detected vehicle steering amount and the detection. It is also possible to use a means for setting the degree of sudden restriction suppression based on the vehicle speed of the vehicle. In these aspects of the vehicle of the present invention, the suppression degree setting means is smaller than normal when the detected vehicle steering amount and / or the detected vehicle speed is during a predetermined steering travel. It can also be a means for setting the degree of sudden restriction suppression.
[0011]
Furthermore, in the vehicle of the present invention, the traveling state detecting means is means having road surface gradient detecting means for detecting a road surface gradient, and the suppression degree setting means is configured to suppress the sudden limit based on the detected road surface gradient. It can also be a means for setting the degree. In this aspect of the vehicle of the present invention, the running state detecting means is means having vehicle speed detecting means for detecting the vehicle speed of the vehicle, and the suppression degree setting means is the detected road surface gradient and the detected It may be a means for setting the sudden limit suppression degree based on the vehicle speed. In the vehicle of the present invention of these aspects, the suppression degree setting means is configured such that when the detected road surface gradient is greater than or equal to a first predetermined gradient and / or when the detected vehicle speed is less than a second predetermined vehicle speed, It may be a means for setting the sudden limit suppression degree to be smaller than usual. Further, in the vehicle according to the present invention of these aspects, the suppression degree setting means may be configured such that when the detected road surface gradient is less than a second predetermined gradient and / or when the detected vehicle speed is less than a third predetermined vehicle speed. Further, it may be a means for setting the sudden limit suppression degree so as to be larger than usual. In this case, the condition that the steering amount of the vehicle is less than the predetermined steering amount may be added as one of the conditions.
[0012]
Alternatively, the vehicle according to the present invention further includes a rotational acceleration detection unit that detects a rotational acceleration of the drive shaft, and the control unit detects the rotation angle of the drive shaft that is detected when a slip is detected by the slip detection unit. The torque output to the drive shaft is limited by using the sudden limit suppression degree as a lower limit value when the required torque required for the drive shaft is limited by a torque limit value set based on acceleration. It may be a means for driving and controlling the electric motor.
[0013]
The vehicle control method of the present invention includes:
A method for controlling a vehicle including an electric motor capable of outputting power to a drive shaft connected to a drive wheel,
(A) detecting slip due to idling of the drive wheel;
(B) detecting a traveling state of the vehicle;
(C) When slip is detected in the step (a), the torque output to the drive shaft is prevented from being suddenly limited based on the running state of the vehicle detected in the step (b). The step of setting the degree of sudden limit suppression as the degree of
(D) driving and controlling the electric motor so that torque output to the drive shaft is limited based on the set sudden limit suppression degree;
It is a summary to provide.
[0014]
In this vehicle control method of the present invention, the sudden limit suppression degree as a degree to suppress the sudden limit of the torque output to the drive shaft based on the running state of the vehicle when the slip is detected. And the electric motor capable of outputting power to the drive shaft is controlled so that the torque output to the drive shaft is limited using the set sudden limit suppression degree. Therefore, the slip can be converged while suppressing a shock at the time of limiting the torque output to the drive shaft with the detection of the slip to a degree based on the running state of the vehicle.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described using examples. FIG. 1 is a configuration diagram showing an outline of the configuration of an automobile 20 according to an embodiment of the present invention. As shown in the figure, the automobile 20 of the embodiment is connected to a drive shaft 28 mechanically connected to drive wheels 62a and 62b via a differential gear 29 using electric power supplied from a battery 26 via an inverter circuit 24. A motor 22 capable of outputting power and an electronic control unit 70 for controlling the entire vehicle are provided.
[0016]
The motor 22 is configured as, for example, a well-known synchronous generator motor that functions as an electric motor and also as a generator, and the inverter circuit 24 converts a plurality of electric power from the battery 26 into electric power suitable for driving the motor 22. It is comprised by the switching element.
[0017]
The electronic control unit 70 is configured as a microprocessor centered on the CPU 72. In addition to the CPU 72, a ROM 74 that stores a processing program, a RAM 76 that temporarily stores data, an input / output port (not shown), and the like. Is provided. The electronic control unit 70 includes a rotational position θd from a rotational position detection sensor 32 that detects the rotational position of the rotational shaft (drive shaft 28) of the motor 22, and wheel speeds that detect the wheel speeds of the drive wheels 62a and 62b. The wheel speed from the sensors 34a and 34b, the wheel speed from the wheel speed sensors 36a and 36b for detecting the respective wheel speeds of the non-driven wheels 64a and 64b, the vehicle speed V from the vehicle speed sensor 52 for detecting the traveling speed of the vehicle, From the road surface gradient θgr from the gradient sensor 54 that detects the gradient of the traveling road surface, the steering angle θst from the snake angle sensor 56 that detects the steering angle of the vehicle, and the shift position sensor 82 that detects the operation position of the shift lever 81. Shift position SP, accelerator pedal position sensor 84 for detecting the depression amount of accelerator pedal 83, accelerator opening degree Acc, brake A brake pedal position BP from a brake pedal position sensor 86 that detects the depression amount of Dar 85 is input via the input port. In addition, a switching control signal to the switching element of the inverter circuit 24 is output from the electronic control unit 70 via the output port.
[0018]
The operation of the automobile 20 configured as described above, particularly the operation for controlling the motor 22 by determining whether or not slippage due to the idling of the drive wheels 62a and 62b has occurred will be described. FIG. 2 is a flowchart illustrating an example of a drive control routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment. This routine is repeatedly executed every predetermined time (for example, every 8 msec).
[0019]
When the drive control routine is executed, the CPU 72 of the electronic control unit 70 first sets the accelerator opening Acc from the accelerator pedal position sensor 84, the vehicle speed V from the vehicle speed sensor 52, and the rotational position θd from the rotational position detection sensor 32. Based on the input accelerator opening Acc and the vehicle speed V, the required torque Td * to be output to the drive shaft 28 is set (step S100). S102). Here, the required torque Td * is set in the embodiment in such a way that the relationship between the accelerator opening Acc, the vehicle speed V, and the required torque Td * is obtained in advance and stored in the ROM 74 as a map, and the accelerator opening Acc and the vehicle speed V are stored. And the corresponding required torque Td * is derived from the map. An example of this map is shown in FIG.
[0020]
Subsequently, the rotational angular acceleration α of the drive shaft 28 is calculated based on the input rotational speed Nd of the drive shaft 28 (step S104), and slip occurs in the drive wheels 62a and 62b based on the calculated rotational angular acceleration α. Slip determination processing is performed to determine whether or not the generated slip has converged (step S106). Here, in the embodiment, the calculation of the rotational angular acceleration α is performed by subtracting the previous rotational speed Nd input in the previous routine from the current rotational speed Nd input in the current routine (current rotational speed Nd−previous rotational speed Nd). ). Note that when the unit of the rotational angular acceleration α is represented by the number of rotations Nd expressed as the number of rotations per minute [rpm], in this embodiment, the execution time interval of this routine is 8 msec, so [rpm / 8 msec] It becomes. Of course, any unit may be adopted as long as the rate of change in the number of rotations can be indicated. Further, the rotational angular acceleration α may be an average of angular accelerations calculated over the past several times (for example, three times) from the current routine in order to reduce the error. Hereinafter, the content of the slip determination process will be described in detail.
[0021]
FIG. 4 is a flowchart illustrating an example of a slip determination processing routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment. When this slip determination processing routine is executed, the CPU 72 of the electronic control unit 70 can determine that the rotational angular acceleration α calculated in step S104 of the drive control routine of FIG. It is determined whether or not αslip is exceeded (step S150). If it is determined that the rotational angular acceleration α exceeds the threshold αslip, it is determined that the drive wheels 62a and 62b have slipped and slip has occurred, and slip Is set to a value 1 (step S152), and this routine is terminated.
[0022]
If it is determined that the rotational angular acceleration α does not exceed the threshold αslip, it is determined whether or not the value of the slip occurrence flag F1 is a value 1 (step S154). When it is determined that the slip occurrence flag F1 is a value 1, it is determined whether or not the rotational angular acceleration α is a negative value and the state continues for a predetermined time or more (steps S156 and S158). When it is determined that the rotational angular acceleration α is a negative value and the state has continued for a predetermined time or more, it is determined that the slip generated in the drive wheels 62a and 62b has converged, and the slip convergence indicating the convergence of the generated slip The flag F2 is set to 1 (step S160), and this routine is terminated. When it is determined that the rotational angular acceleration α is not a negative value, or when it is determined that the state has not continued for a predetermined time or more even if the angular acceleration α is a negative value, the generated slip has not yet converged. This routine is terminated. If it is determined in step S154 that the slip occurrence flag F1 is not a value 1, it is determined that no slip has occurred, and this routine is terminated.
[0023]
Returning to the drive control routine of FIG. 2, when the slip is determined in this way, processing according to the determination result is performed (steps S108 to S116). Specifically, when it is determined that both the slip generation flag F1 and the slip convergence flag F2 are 0 and no slip has occurred (grip state), the required torque Td * set in step S102 is set to the motor 22. Is set to the target torque Tm * (step S110), a process for controlling the drive of the motor 22 based on the set target torque Tm * is performed (step S116), and this routine is terminated. Further, when it is determined that the slip occurrence flag F1 is the value 1 and the slip convergence flag F2 is the value 0 and the slip has occurred, the slip occurrence processing is performed (step S112), and both the slip occurrence flag F1 and the slip convergence flag F2 are performed. When it is determined that the generated slip has converged, the slip convergence process is performed (step S114), and the motor 22 is driven and controlled based on the target torque Tm * of the motor 22 set in each process. Processing is performed (step S116), and this routine is terminated. The drive control of the motor 22 is specifically performed by outputting a switching control signal to the switching element of the inverter circuit 24 so that a torque corresponding to the target torque Tm * is output to the drive shaft 28. Hereinafter, the processing at the time of slip occurrence and the processing at the time of slip convergence will be described in detail.
[0024]
The slip generation process is a process of setting the target torque Tm * of the motor 22 by limiting the required torque Td * required for the drive shaft 28 in order to suppress the generated slip. It is executed by a routine. When the slip generation processing routine is executed, the CPU 72 of the electronic control unit 70 first determines whether or not the rotational angular acceleration α calculated in step S104 of the drive control routine of FIG. 2 exceeds the peak value αpeak. (Step S200) When the rotational angular acceleration α exceeds the peak value αpeak, processing for updating the peak value αpeak to the rotational angular acceleration α is performed (Step S202). Here, the peak value αpeak is basically a value when the rotational angular acceleration α increases to show a peak due to the occurrence of slip, and the value 0 is set as an initial value. Accordingly, the peak value αpeak is sequentially updated to the value of the rotational angular acceleration α until the rotational angular acceleration α increases and reaches a peak, and when the rotational angular acceleration α reaches the peak, the rotational angular acceleration α is updated. Is fixed as the peak value αpeak. When the peak value αpeak is set in this way, a process of setting a torque upper limit value Tmax that is an upper limit value of torque that may be output from the motor 22 in order to suppress the slip generated based on the peak value αpeak is performed ( Step S204). In the embodiment, this processing is performed using the map illustrated in FIG. FIG. 6 is a map showing the relationship between the rotational angular acceleration α and the torque upper limit value Tmax. In this map, as shown in the figure, the torque upper limit value Tmax decreases as the rotational angular acceleration α increases. Therefore, as the rotational angular acceleration α increases and the peak value αpeak increases, that is, as the degree of slip increases, a smaller value is set as the torque upper limit value Tmax, and the torque output from the motor 22 is limited accordingly. become.
[0025]
When the torque upper limit value Tmax is set in this way, it is next determined whether or not the execution of this slip occurrence processing routine is the first execution (step S206), and if it is determined that the execution is the first execution. In order to suppress the rapid limitation of the torque output to the drive shaft 28, the adjustment torque value TL is set as a lower limit value when the required torque Td * of the drive shaft drive shaft 28 is limited by the set torque upper limit value Tmax. An adjustment torque setting process is performed (step S208). The adjustment torque setting process is executed by an adjustment torque setting process routine illustrated in FIG. Hereinafter, the adjustment torque setting process will be described.
[0026]
When the adjustment torque setting process routine is executed, the CPU 72 of the electronic control unit 70 first sets the slip generation torque Tmslip as the torque output to the drive shaft 28 when the slip occurs (step S250). In the embodiment, the slip generation torque Tmslip is set by setting the previous target torque Tm * of the motor 22 set in steps S110 to S114 in the previous drive control routine of FIG. 2 as the slip generation torque Tmslip.
[0027]
Next, the road surface gradient θgr from the gradient sensor 54 and the steering angle θst from the snake angle sensor 56 are input (step S252), and the input road surface gradient θgr and steering angle θst are input at step S100 of the drive control routine of FIG. Based on the measured vehicle speed V, it is determined whether or not a predetermined steering travel is being performed (step S254), and whether or not the road surface gradient θgr is a slope and the vehicle speed V is an extremely low vehicle speed (step S256). Then, it is determined whether or not the road surface gradient θgr is a flat road and the vehicle speed V is a low vehicle speed (step S260). Here, the determination as to whether or not the vehicle is in a predetermined steering traveling is, for example, whether or not the vehicle speed V and the steering angle θst belong to a predetermined steering traveling region where the steering angle θst is relatively large and the vehicle speed V is high. This is done by determining whether or not. An example of the map used for this determination is shown in FIG. Whether the road surface gradient θgr is a slope and the vehicle speed V is an extremely low vehicle speed is determined by determining whether the road surface gradient θgr is equal to or greater than a predetermined gradient (for example, a gradient of about 14% or 15%). It is performed by determining whether or not the vehicle speed is lower than the vehicle speed (for example, a vehicle speed of about 5 to 10 km / h). Further, whether the road surface gradient θgr is a flat road and the vehicle speed V is a low vehicle speed is determined based on whether the road surface gradient θgr is less than a predetermined gradient (for example, a gradient of about 3% or 5%) and the vehicle speed V is This is performed by determining whether or not the vehicle speed is lower than a predetermined vehicle speed (for example, a vehicle speed of about 20 to 30 km / h).
[0028]
As a result of such determination, when it is determined that the vehicle is in a predetermined steering traveling state, or when the road surface gradient θgr is determined to be a slope and the vehicle speed V is extremely low, the vehicle at the time of occurrence of the slip is in a relatively unstable state. Yes, based on the slip generation torque Tmslip input in step S250, judging that it is necessary to prioritize the rapid convergence of the slip rather than suppressing the sudden limit on the required torque Td * greatly. When the adjustment torque TL at the time of slip convergence priority is set (step S258), and it is determined that the road surface gradient θgr is a flat road and the vehicle speed V is a low vehicle speed without satisfying the conditions of steps S254 and S256, when slip occurs This vehicle is in a relatively stable state, and the sudden limit on the required torque Td * is greatly suppressed rather than the quick convergence of the slip. It is determined that it is necessary to give priority to mitigating the shock, and the adjustment torque TL at the time of shock mitigation priority is set based on the slip occurrence torque Tmslip input in step S250 (step S262), and steps S254, S256, and S260. If it is determined that none of the above conditions is satisfied, the adjustment torque TL at the normal time is set based on the slip generation torque Tmslip input in step S250 so as to balance the rapid convergence of the slip and the relaxation of the shock. (Step S264), this routine is finished. In the embodiment, the adjustment torque TL is set in such a manner that the relationship between the slip occurrence torque Tmslip and the adjustment torque TL is stored in advance in the ROM 74 as a map, and when the slip occurrence torque Tmslip is given, the corresponding adjustment from the map is performed. The torque TL was derived and set. An example of this map is shown in FIG. As shown in the drawing, the adjustment torque TL at the time of slip convergence priority is set to be larger than that at the normal time, and the adjustment torque TL at the time of shock relaxation priority is set to be smaller than the normal time.
[0029]
Returning to the slip occurrence processing routine of FIG. 5, when the adjustment torque TL is set, it is determined whether or not the set adjustment torque TL is larger than the torque upper limit value Tmax set in step S204 (step S210). If it is determined that the torque TL is larger than the torque upper limit value Tmax, the torque upper limit value Tmax is adjusted to become the adjustment torque TL (step S212). Then, the smaller one of the required torque Td * set in step S102 of the drive control routine of FIG. 2 and the torque upper limit value Tmax set in step S204 or the torque upper limit value Tmax adjusted in step S212 is determined by the motor 22. Is set as the target torque Tm * (step S214), and this routine is terminated. Thus, when the adjustment torque TL is larger than the torque upper limit value Tmax, the torque upper limit value Tmax set to suppress the slip is adjusted to the adjustment torque TL to limit the required torque Td *. A sudden restriction of the torque Td * can be suppressed, and a torque shock that can occur when the motor 22 is driven and controlled can be prevented. At this time, the adjustment torque TL is determined to be a relatively unstable state when the vehicle is determined to be traveling at a predetermined steering speed or when the vehicle is determined to be traveling on a slope and at an extremely low vehicle speed. Is set to a small value and priority is given to quick convergence of slip, and when it is determined that the vehicle is running on a flat road and a low vehicle speed instead of a predetermined steering running, the torque is set to a larger value than usual. Since priority is given to the relaxation of the shock, the torque shock accompanying the suppression of the slip can be effectively reduced while ensuring the running stability of the vehicle.
[0030]
When the slip generation process is repeatedly executed and it is determined in step S206 that the slip generation process is not executed for the first time, a process of updating the adjustment torque TL set in step S208 is performed (step S216). In the embodiment, the process of updating the adjustment torque TL is performed by newly resetting the adjustment torque TL obtained by subtracting the predetermined value Rate from the adjustment torque TL previously set or updated (previous TL) as the adjustment torque TL. did. When the adjustment torque TL is updated, when the updated adjustment torque TL is larger than the torque upper limit value Tmax, the updated adjustment torque TL is adjusted as the torque upper limit value Tmax (steps S210 and S212), the required torque Td *, and the step S204. A process of setting the smaller one of the torque upper limit value Tmax set in step S2 or the torque upper limit value Tmax adjusted in step S212 as the target torque Tm * of the motor 22 is performed (step S214), and this routine is terminated.
[0031]
The slip convergence process is a process for releasing (releasing) the restriction applied to the required torque Td * when the generated slip converges, and is executed by the slip convergence process routine of FIG. When the slip convergence processing routine is executed, the CPU 72 of the electronic control unit 70 first multiplies the slip generation torque Tmslip set in the adjustment torque setting processing routine of FIG. Is set (step S300), and the required torque Td * set in step S102 of the drive control routine of FIG. 2 is guarded with the set torque upper limit value Tmax (step S302). Here, the coefficient K is set within a range of 0 to 1 in order to prevent re-slip. Then, it is determined whether or not a predetermined time has elapsed since the first execution of the slip convergence time processing routine was started (step S304). If it is determined that the predetermined time has not elapsed, the present routine is terminated, and if it is determined that the predetermined time has elapsed, both the slip generation flag F1 and the slip convergence flag F2 are reset to a value of 0. (Step S306), and this routine is finished. Therefore, until a predetermined time has elapsed after the first execution of the slip convergence time processing routine is started, a predetermined ratio of torque (Tmslip · K), the required torque Td * is limited, and when the predetermined time has elapsed, the limitation by the torque upper limit value Tmax is completely released, and the required torque Td * is set as the target torque Tm * of the motor 22, and the motor 22 Is driven and controlled.
[0032]
FIG. 11 is an explanatory diagram for explaining how the target torque Tm * and the rotational angular acceleration α of the drive shaft 28 change with time when the torque output to the drive shaft 28 is limited due to the occurrence of slip. When slip occurs when the rotational angular acceleration α of the drive shaft 28 exceeds the threshold αslip at time t1, a torque upper limit value Tmax is set according to the rotational angular acceleration α. At this time, the vehicle tends to be stable based on the steering amount θst of the vehicle, the road surface gradient θgr, and the vehicle speed V in order to mitigate the torque shock accompanying the rapid torque limitation to the drive shaft 28 by the torque upper limit value Tmax. The larger value is set as the adjustment torque TL in favor of the relaxation of the torque shock, and the torque upper limit value Tmax set when the adjustment torque TL is larger than the torque upper limit value Tmax is adjusted to the adjustment torque TL. At time t2 immediately after the occurrence of slip, the target torque Tm * of the motor 22 is set by being limited by the adjustment torque TL. Thereafter, the set adjustment torque TL is gradually updated to a small value, and the torque output to the drive shaft 28 is limited to the torque upper limit value Tmax corresponding to the peak rotational angular acceleration α. It is determined that slip has converged at time t3 when a predetermined time has elapsed since the rotation angular acceleration α has decreased to a negative value due to the torque limitation, and the limitation on the torque output to the drive shaft 28 is released. Is done.
[0033]
According to the automobile 20 of the embodiment described above, the torque upper limit value Tmax set for suppressing the slip is smaller than the adjustment torque TL set so as to decrease as the traveling state of the vehicle tends to become unstable. When the torque is small, the adjustment torque TL is newly adjusted as the torque upper limit value Tmax, and the required torque Td * to be output to the drive shaft 28 is limited to be equal to or less than the adjusted torque upper limit value Tmax. That is, when the running state of the vehicle is relatively unstable when the slip occurs, priority is given to the quick convergence of the slip, and the traveling state of the vehicle is relatively stable when the slip occurs. In some cases, priority is given to mitigating torque shock, so that torque shock associated with slip suppression can be effectively mitigated while ensuring vehicle running stability.
[0034]
In the automobile 20 according to the embodiment, the torque upper limit value Tmax is adjusted by selecting one of the three types of adjustment torque TL (when slip convergence is prioritized, when normal, and when shock is prioritized) according to the running state of the vehicle. However, the torque upper limit value Tmax may be adjusted by selecting one of two types or four or more types of adjustment torques TL according to the traveling state of the vehicle.
[0035]
In the automobile 20 of the embodiment, in the process of step S254 of the adjustment torque setting process routine of FIG. 7, it is determined whether or not the vehicle is in a predetermined steering travel based on the steering angle θst and the vehicle speed V. However, it may be determined based on only the steering angle θst whether or not the steering angle of the vehicle is greater than or equal to a predetermined steering angle.
[0036]
In the automobile 20 of the embodiment, in the process of step S256 of the adjustment torque setting process routine of FIG. 7, the adjustment torque TL at the time of slip convergence priority is set when the road surface gradient θgr is a slope and the vehicle speed V is an extremely low vehicle speed. However, regardless of the vehicle speed V, the adjustment torque TL at the time of slip convergence priority may be set when the road surface gradient θgr is equal to or greater than a predetermined gradient that can be regarded as a slope. In the process of step S258, the adjustment torque TL at the time of shock relaxation priority is set when the road surface gradient θgr is a flat road and the vehicle speed V is low. However, the road surface gradient θgr is set regardless of the vehicle speed V. The adjustment torque TL at the time of shock relaxation priority may be set when the slope is less than a predetermined gradient that can be regarded as a flat road.
[0037]
In the vehicle 20 of the embodiment, in the process of step S254 of the adjustment torque setting process routine of FIG. 7, it is determined whether or not a predetermined steering traveling is being performed using the steering angle θst directly detected by the snake angle sensor 56. However, the steering angle θst is estimated from the deviation between the rotational speeds Nr and Nl of the non-driven wheels 64a and 64b detected by the wheel speed sensors 36a and 36b, and a predetermined value is used using the estimated steering angle θst. It may be determined whether the vehicle is steering.
[0038]
In the automobile 20 of the embodiment, whether the road is a slope or a flat road using the road surface gradient θgr directly detected by the gradient sensor 56 in the processing of steps S256 and S260 of the adjustment torque setting processing routine of FIG. In the process of traveling or stopping, the vehicle is driven in the direction along the road surface gradient by the road surface gradient θgr or the road surface gradient θgr from the relationship between the torque output to the drive shaft 28 and the acceleration of the vehicle. The force acting on the vehicle may be estimated, and the road surface gradient θgr or the road surface gradient θgr may be used to determine whether the road is a slope or a flat road. .
[0039]
In the automobile 20 of the embodiment, the torque upper limit value Tmax is derived based on the rotational angular acceleration α and the adjustment torque TL is derived based on the running state of the vehicle, and is adjusted when the adjustment torque TL is larger than the torque upper limit value Tmax. The torque upper limit value Tmax is adjusted so as to be the torque TL to limit the required torque Td *, but an element corresponding to the adjustment torque TL is expected based on the rotational angular acceleration α and the running state of the vehicle. The torque upper limit value Tmax may be directly derived.
[0040]
Although the embodiment has been described as applied to the automobile 20 including the motor 22 mechanically connected to the drive shafts connected to the drive wheels 62a and 62b so that power can be directly output, As long as the vehicle includes an electric motor capable of output, it may be applied to a vehicle having any configuration. For example, the present invention may be applied to a so-called series-type hybrid vehicle including an engine, a generator connected to the output shaft of the engine, and a motor that outputs power to the drive shaft using generated power from the generator. Further, as shown in FIG. 12, the engine 122, the planetary gear 126 connected to the engine 122, the motor 124 capable of generating electricity connected to the planetary gear 126, and the planetary gear 126 are connected to the drive wheels 62a and 62b. The present invention can also be applied to a so-called mechanical distribution type hybrid vehicle 120 that includes a motor 22 that is mechanically connected to a drive shaft so that power can be output to the connected drive shaft. 222 has an inner rotor 224a connected to the output shaft 222 and an outer rotor 224b attached to the drive shaft connected to the drive wheels 62a and 62b. The inner rotor 224a and the outer rotor 224b are relatively driven by electromagnetic action. A motor 224 that rotates in a rotating manner and power can be output to the drive shaft. It can also be applied to a hybrid vehicle 220 of a so-called electric distribution type and a motor 22 which is connected. Alternatively, as shown in FIG. 14, the motor 22 connected to the drive shaft connected to the drive wheels 62a and 62b via a transmission 324 (such as a continuously variable transmission or a stepped automatic transmission) and the clutch CL The present invention can also be applied to a hybrid vehicle 320 that includes an engine 322 connected to the rotating shaft of the motor 22 via the motor. At this time, as a control when slip occurs in the drive wheel, the torque output to the drive shaft mainly by controlling the motor mechanically connected to the drive shaft from the speed of output response in the control, etc. However, it is also possible to control another motor or control the engine in cooperation with this motor control.
[0041]
The embodiments of the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the gist of the present invention. Of course you get.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of the configuration of an automobile 20 according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an example of a drive control routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment.
FIG. 3 is a map showing a relationship among an accelerator opening Acc, a vehicle speed V, and a required torque Td *.
FIG. 4 is a flowchart illustrating an example of a slip determination processing routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment.
FIG. 5 is a flowchart illustrating an example of a slip generation processing routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment.
FIG. 6 is a map showing the relationship between the rotational angular acceleration α of the drive shaft 28 and the torque upper limit value Tmax.
FIG. 7 is a flowchart illustrating an example of an adjustment torque setting process routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment.
FIG. 8 is a map showing a relationship between a vehicle speed V, a steering angle θst, and a predetermined steering travel region.
FIG. 9 is a map showing the relationship between slip generation torque Tmslip and adjustment torque TL.
FIG. 10 is a flowchart illustrating an example of a slip convergence processing routine executed by the electronic control unit 70 of the automobile 20 according to the embodiment.
FIG. 11 is an explanatory diagram showing how the target torque Tm * and the rotational angular acceleration α change over time when the torque output to the drive shaft 28 is limited due to the occurrence of slip.
FIG. 12 is a configuration diagram showing an outline of a configuration of an automobile 120 according to a modified example.
FIG. 13 is a configuration diagram showing an outline of a configuration of an automobile 220 according to a modified example.
FIG. 14 is a configuration diagram showing an outline of a configuration of an automobile 320 according to a modified example.
[Explanation of symbols]
20, 120, 220, 320 Car, 22 Motor, 24 Inverter circuit, 26 Battery, 28 Drive shaft, 29 Differential gear, 32 Rotation position detection sensor, 52 Vehicle speed sensor, 54 Gradient sensor, 56 Snake angle sensor, 62a, 62b Drive Wheel, 70 electronic control unit, 72 CPU, 74 ROM, 76 RAM, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 122, 222, 322 Engine, 124 motor, 126 planetary gear, 224 motor, 224a inner rotor, 224b outer rotor, 324 transmission.

Claims (11)

A vehicle including an electric motor capable of outputting power to a drive shaft connected to a drive wheel,
Slip detecting means for detecting slip due to idling of the drive wheel;
Traveling state detecting means for detecting the traveling state of the vehicle;
Rotational acceleration detecting means for detecting rotational acceleration of the drive shaft;
When slip is detected by the slip detection means, a torque limit value for limiting the torque output to the drive shaft is set based on the detected rotational acceleration of the drive shaft, and the detected vehicle A sudden limit suppression degree is set as a degree at which the torque output to the drive shaft is restrained from being suddenly limited based on a running state, and the set within the range of the set sudden limit suppression degree A vehicle comprising: control means for restricting a required torque required for the drive shaft based on a torque limit value and controlling the drive of the electric motor. The vehicle according to claim 1, wherein the control means is a means for setting the degree of rapid restriction suppression so that the detected traveling state of the vehicle tends to become unstable. The vehicle according to claim 1 or 2,
The traveling state detection means is means having steering amount detection means for detecting the steering amount of the vehicle,
The control means is means for setting the sudden limit suppression degree based on the detected steering amount of the vehicle. The vehicle according to claim 3,
The travel state detection means is means having vehicle speed detection means for detecting the vehicle speed of the vehicle,
The control means is a means for setting the sudden limit suppression degree based on the detected steering amount of the vehicle and the detected vehicle speed of the vehicle. The control means is a means for setting the degree of sudden limit suppression so that the detected vehicle steering amount and the detected vehicle speed are smaller than normal when the detected vehicle speed is during a predetermined steering travel. Item 5. The vehicle according to item 3 or 4. A vehicle according to any one of claims 1 to 5,
The traveling state detection means is means having road surface gradient detection means for detecting a road surface gradient,
Wherein said control means is a means for setting the order of the sudden restriction suppressed on the basis of the detected road surface gradient vehicle. The vehicle according to claim 6, wherein
The travel state detection means is means having vehicle speed detection means for detecting the vehicle speed of the vehicle,
The control means is means for setting the degree of sudden restriction suppression based on the detected road surface gradient and the detected vehicle speed. When the detected road surface gradient is greater than or equal to a first predetermined gradient and / or when the detected vehicle speed is less than a second predetermined vehicle speed, the control means sets the sudden limit suppression degree to be smaller than normal. The vehicle according to claim 6 or 7, which is means for setting. The control means is greater than normal when the detected road gradient is less than a second predetermined gradient and / or when the detected vehicle speed is less than a third predetermined vehicle speed that is greater than the second predetermined vehicle speed. The vehicle according to claim 8, which is means for setting the sudden limit suppression degree. The vehicle according to any one of claims 1 to 9 , wherein the electric motor is a common electric motor for left and right wheels as the driving wheels. A method for controlling a vehicle including an electric motor capable of outputting power to a drive shaft connected to a drive wheel,
(A) detecting slip due to idling of the drive wheel;
(B) detecting a traveling state of the vehicle;
(C) detecting the rotational acceleration of the drive shaft;
(D) when slip due to idling of the drive wheel is detected, a torque limit value for limiting the torque output to the drive shaft is set based on the detected rotational acceleration of the drive shaft, and the detection Based on the travel condition of the vehicle that has been set, a sudden limit suppression degree is set as a degree to suppress the sudden limitation of the torque output to the drive shaft, and within the set sudden limit suppression degree And controlling the drive of the electric motor by limiting a required torque required for the drive shaft based on the set torque limit value .

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