JP7364072B2 - Vehicle control device - Google Patents

Description

The present disclosure relates to a vehicle control device that suppresses acceleration that is not intended by a driver.

Conventionally, when the accelerator is turned on in a low speed range, when the shift lever is shifted from the neutral range (N range) to another range, such as the driving range (D range, 2 range, etc.) or reverse range (R range). In some cases, acceleration may occur that makes the driver feel uncomfortable.

Regarding this point, in a vehicle that runs using the driving force of the engine, if the accelerator pedal is depressed while the automatic transmission is in the N range, the vehicle enters a so-called racing state, which increases engine noise and vibrations. Therefore, the driver can be aware that the accelerator pedal is being depressed, and even if the driver shifts from the N range to another range in this state, it is thought that there will not be many situations where the driver will feel uncomfortable. However, in an electric vehicle that runs using the driving force of a motor, no noise or vibration is generated even if the driver depresses the accelerator pedal while the N range is selected. For this reason, it is conceivable that the driver may shift from the N range to the D range, etc., while deeply depressing the accelerator pedal without being particularly conscious of it. In particular, in vehicles where the shift lever and the like are operated by a drive-by-wire system, the shift operation is relatively easy, so the possibility that such a situation will occur is even higher.

Japanese Patent Publication No. 6-98419 (see Figure 4 on page 6, Figure 8 on page 9, etc.) states that when the N range is selected in an electric vehicle, the accelerator opening is considered to be 0%. , discloses an output reduction control technology called "smoothing processing" that gradually increases the output torque command value to the required torque corresponding to the actual accelerator opening when the N range is switched to the driving range. has been done. This is said to prevent the output torque from suddenly increasing when changing ranges, even if the driver depresses the accelerator pedal without being particularly conscious of it.

According to Japanese Patent Application Publication No. 6-98419 (see Figure 4 on page 6, Figure 8 on page 9, etc.), when shifting from N range to other range while depressing the accelerator pedal, the output Acceleration is uniformly suppressed by smoothing the torque command value. For this reason, there is a problem that fine control corresponding to the operating state cannot be performed.

Specifically, depending on the driving state, there is a problem in that even though the vehicle originally wants to accelerate, acceleration is suppressed because the smoothing process is continuing. Furthermore, the driver shifts from the N range to another range while depressing the accelerator pedal, and after that, the driver notices an odd sensation of acceleration and temporarily reduces the amount of accelerator pedal depression, and then depresses the accelerator pedal to accelerate again. In such a case, there is a problem in that even though acceleration is originally desired, acceleration is suppressed because the smoothing process is continuing.

The present disclosure provides a vehicle control device that can suppress unintended acceleration by a driver and provide appropriate acceleration according to driving conditions when a shift operation is performed from the N range to another range while depressing the accelerator pedal. Related.

According to one aspect of the present disclosure, the vehicle control device includes an electric motor that is a drive source for traveling, a speed detection unit that detects vehicle speed, an accelerator opening detection unit that detects accelerator opening, and a selected A shift position detection section that detects a shift position, a driver request torque calculation section that calculates a driver request torque based on the accelerator opening degree, and an output torque command section that commands an output torque to the electric motor. The output torque command unit is configured to: when the shift position is switched from a neutral range to another range in an accelerator ON state where the vehicle speed is less than a predetermined speed and the accelerator opening is equal to or greater than a first predetermined value; Output increase rate reduction control is performed to reduce the increase rate of the output torque to a first increase rate lower than the required torque increase rate according to the driver request torque, and the output increase rate reduction control is performed when the accelerator opening is It is released in the accelerator OFF state below a second predetermined value that is lower than the first predetermined value.

According to the aspect of the present disclosure, the increase rate of the output torque due to the output increase rate reduction control may be configured such that the increase rate is set to be larger as the vehicle speed at the time of starting the vehicle is higher. .

According to the aspect of the present disclosure, the output torque command unit is configured such that when the accelerator opening changes to the accelerator ON state again after the accelerator opening changes from the accelerator ON state to the accelerator OFF state, A configuration may be adopted in which additional output control is performed to set the increase rate of the output torque to a second increase rate that is greater than the first increase rate and less than or equal to the required torque increase rate.

According to the aspect of the present disclosure, the increase rate of the output torque due to the output increase rate reduction control is set such that when the vehicle speed has a negative value, the larger the absolute value of the vehicle speed is, the larger the increase rate is. configuration may be adopted.

According to the aspect of the present disclosure, the rate of increase in the output torque due to the output increase rate reduction control has a minimum value when the vehicle speed is a positive value, and has a minimum value when the vehicle speed is zero. A configuration that is a value may be adopted.

FIG. 1 is a time chart showing a control example of an embodiment of the present disclosure. FIG. 2 is a time chart showing a modification of the embodiment corresponding to FIG. FIG. 3 is a graph showing the relationship between speed and rate of increase in output torque. FIG. 4 is a flowchart showing an example of control. FIG. 5 is a schematic diagram of a vehicle and a vehicle control device.

Embodiments of the present disclosure will be described based on FIGS. 1 to 5. The vehicle control device 10 of the present embodiment is configured such that when the driver depresses the accelerator pedal 25 in a low speed range such as when the vehicle 20 is running at a low speed or when the vehicle 20 is stopped, the shift lever 26 is in the neutral range. This device controls the output torque to the driving wheels 28 and 29 so that the driver does not feel any discomfort in acceleration when the vehicle is operated from the N range (hereinafter referred to as N range) to another range.

Here, the low speed range is a state in which the vehicle speed, that is, the speed of the vehicle 20 is below a predetermined speed, and is such a low speed that the driver operates the shift lever 26 to change the shift position from the N range to another range. state (including forward and backward) or a stopped state of the vehicle 20. In this embodiment, the predetermined speed is set to 20 km/h during forward movement. Other ranges other than the N range include, for example, driving ranges such as the drive range (D range) and second range (2 range) in which forward drive torque is applied to the drive wheels 28 and 29, and drive ranges in which reverse drive torque is applied. This applies to the reverse range (R range) provided.

FIG. 5 is a schematic diagram of a vehicle 20 equipped with the vehicle control device 10 according to the present embodiment. The vehicle 20 is an electric vehicle that includes an electric motor 22 that generates driving force using electric power, and in this embodiment, it is a plug-in hybrid electric vehicle. The engine 24 drives the generator to perform a power generation function, thereby supplying electric power to the electric motor 22, which is a drive source for traveling, and storing electricity in the storage battery 23. Furthermore, power storage in the storage battery 23 is also performed by connecting the vehicle 20 and a ground-side power source using a dedicated cable. In this embodiment, the electric motor 22 includes a front motor 22a and a rear motor 22b, and the front motor 22a and the rear motor 22b separately drive both the front and rear drive wheels 28 and 29 via the differential 27, respectively. However, the vehicle 20 may be configured such that one electric motor 22 drives all of the drive wheels 28 and 29.

The vehicle control device 10 includes a speed detection unit 1 that detects the vehicle speed, an accelerator opening detection unit 2 that detects the accelerator opening based on information from an accelerator position sensor, and a selected shift position based on information from the shift position sensor. It includes a shift position detecting section 3 for detecting a shift position, a driver required torque calculating section 4 for calculating a driver required torque based on an accelerator opening degree, and an output torque commanding section 5 for instructing an output torque to an electric motor. These are provided in an electronic control unit 21. The vehicle 20 also includes sensors that detect various information necessary for driving control, such as a torque sensor that detects the output torque from the electric motor 22 and a sensor that detects the amount of depression of the brake pedal. . Information from these sensors is transmitted to a control section 6 that controls overall control of the electronic control unit 21.

The speed detection unit 1 detects the traveling speed of the vehicle 20 based on information from vehicle speed sensors provided on the drive wheels 28, 29, etc. Furthermore, the speed detection unit 1 has a function of determining whether the vehicle speed is equal to or lower than a first predetermined speed (20 km/h in the embodiment). The speed detection unit 1 determines that the vehicle is in a low speed range if the vehicle speed is less than or equal to a predetermined speed, and determines that the vehicle is not in a low speed region if the vehicle speed is greater than the predetermined speed.

The accelerator opening detection unit 2 can detect the accelerator opening, that is, the amount of depression of the accelerator pedal 25 by the driver, as a numerical value between 0% and 100%. Here, 0% is a state where the accelerator pedal 25 is not depressed at all, and 100% is a state where the accelerator pedal 25 is depressed to the maximum. Based on this accelerator opening degree, the driver request torque calculation unit 4 can detect whether there is an acceleration request for the vehicle 20 and the magnitude of the acceleration request (accelerator request torque).

The shift position detection section 3 detects the shift position of the automatic transmission based on information from a shift position sensor that detects the position of the shift lever 26. Furthermore, when the shift position is switched, information about the switch is transmitted to the electronic control unit 21. Therefore, for example, when the shift position is switched from the N range to a range other than the N range, information that the shift has been made is transmitted to the control section 6 of the electronic control unit 21. The information that the shift position has been switched may be, for example, a signal that is sent at the time of the shift, or a signal that indicates which position the shift position is at every minute fixed time. In addition to the determination, if the shift position signal is the same between the previous determination and the current determination, there is no switching, and the shift position signals are different, it may be determined that there has been switching. The shift position information also includes information on the current shift position and information on whether the shift position has been changed as described above.

The output torque command unit 5 has a function of commanding the electric motor 22 to output torque. FIG. 4 shows the calculation of output torque and the flow of commands by the output torque command section 5. The symbols p1, p2, and p3 in the figure are information on the accelerator opening (accelerator position sensor voltage), shift position, and vehicle speed, respectively. Symbols p4, p5, p6, and p7 in the figure are information on the drive mode, accelerator request torque, creep torque, and request regeneration torque, respectively. The drive mode is a driving mode selected by the driver from among, for example, normal mode, eco mode, and sport mode. The accelerator required torque and creep torque are calculated by the driver required torque calculation unit 4 based on information on the accelerator opening degree, information from the torque sensor, and various other information representing the driving state. Further, the driver required torque calculation unit 4 calculates the driver required torque (reference required torque) based on information such as the drive mode, accelerator required torque, and creep torque. Note that the required regenerative torque is calculated by the control unit 6 according to driving conditions such as the vehicle speed and the degree of braking at that time. The output torque command unit 5 commands the electric motor 22 to output torque by commanding an increase rate of the output torque with respect to the output torque at that time. In other words, in normal control, in order to make the current output torque match the driver required torque (reference required torque), an index indicating the rate at which the current output torque should be increased or decreased, that is, the required torque increase rate commanded by.

In the control step s1 of FIG. 4, when it is determined that the shift position has changed from the N range to another range (the D range is exemplified in the figure), the vehicle speed is less than a predetermined speed, and the accelerator pedal is It is determined whether the opening is in the accelerator ON state. Whether the accelerator opening is in the accelerator ON state is determined by whether the accelerator opening is equal to or greater than a first predetermined value α1, which is an accelerator ON threshold. In step s2, if it is determined that the conditions are met in step s1, a reduction in the rate of increase in output torque is determined. Here, in step s3, the driver required torque (reference required torque) is calculated based on the drive mode, accelerator required torque, creep torque, etc., and this is used as the reference value in the previous stage for reducing the output torque. Become.

In step s5, the standard required torque is corrected, that is, the increase rate of the output torque is reduced, and the output torque is calculated in accordance with the operating state. However, at this time, correction according to the drive mode shown in step s4 is performed, and the final increase rate of the output torque is determined. Here, the output torque increase rate is set to a relatively lower value than the required torque increase rate that is set in normal control to match the output torque at that point with the driver required torque (reference required torque). The increase rate is reduced to the set first increase rate. The control for reducing the output torque increase rate from the required torque increase rate to the first increase rate in this manner is hereinafter referred to as output increase rate reduction control. Then, in step s6, an output torque is commanded to each of the front and rear electric motors 22a and 22b based on the first increase rate (required motor torque (front) indicated by p8 in FIG. 4, (See required motor torque 8 (rear) shown on page 9). Note that if there is a required regenerative torque indicated by symbol p7, that required regenerative torque is reflected in the final output torque that is commanded. Further, this output increase rate reduction control is canceled when the accelerator opening degree becomes less than the second predetermined value α2, which is lower than the first predetermined value α1, and the accelerator is turned off.

FIG. 1 is a time chart showing a control example of an embodiment of the present disclosure. An example of the control will be explained based on the time chart of FIG. Assume that the shift position is switched from the N range to the D range at the a0 point indicated by symbol (a) in FIG. At this time, the accelerator opening degree at point b1 shown in symbol (b) in FIG. Further, as shown by symbol (d) in FIG. 1, the vehicle speed is in a low speed range of less than a predetermined speed of 20 km/h. As shown by arrow A, the flag changes from 0 to 1 at the point c0 shown by symbol (c) in FIG. 1 based on the shift position change and information on the accelerator ON state, reducing the rate of increase in output torque. A decision is made.

The symbol e1 shown in symbol (e) in FIG. 1 indicates the reference required torque based on the accelerator opening degree. The solid line indicated by symbol (f) in FIG. 1 is the output torque after reducing the rate of increase, and the chain line is the reference required torque before performing the reduction correction. As a result, the required motor torque commanded to the electric motor 22 is reduced from the chain line indicated by symbol (g) in FIG. 1 to the solid line. Here, the command for the output torque is given using a numerical value representing the rate of increase in the output torque. Specifically, when it is determined that output increase rate reduction control should be performed, the normally used output torque increase rate restriction MAP for each drive mode is switched to a suppression MAP for output increase rate reduction control. Then, a command for the increase rate is issued according to each operating state.

In the control example shown in FIG. 1, the rate of increase in the output torque is corrected to be greatly reduced discontinuously in response to the information indicated by arrow B at the h0 point indicated by symbol (h) in FIG. Thereafter, as the vehicle speed increases, the rate of increase in the output torque decreases slightly as indicated by h2, and then gradually increases as the vehicle speed increases, as indicated by h3. In other words, the rate of increase in output torque due to the output increase rate reduction control is set so that the rate of increase increases as the vehicle speed increases in most speed ranges during forward movement (starting), except during forward slight movement. For example, the minimum value of the increase rate at the h1 point corresponds to the output torque at the f1 point with respect to a predetermined low vehicle speed (during forward slight movement) shown at the d1 point. After that, the rate of increase gradually increases as the vehicle speed increases (symbol h3), and the output torque (symbol f3) and required motor torque (symbol g3) also gradually increase until the vehicle speed reaches 20 km/h. At the point where the output increase rate reduction control is completed upon receiving the information indicated by arrow E. Regarding the change in vehicle speed, symbol (d) in FIG. 1 indicates a case where the symbol d2 indicates that the output increase rate reduction control is not performed, and a symbol d3 indicates a case where the output increase rate reduction control is performed. Here, the rate of increase in vehicle speed gradually increases as the vehicle speed increases. This is because the rate of increase in output torque increases as the vehicle speed increases.

Here, there is a literature that generally states that the time during which the driver does not feel dissatisfied with the response (time lag) from when the driver operates to when the vehicle actually reacts is within 1 second. Furthermore, it is said that when the acceleration exceeds 0.1G, the driver feels a sense of acceleration. For this reason, the first predetermined value α1 regarding the accelerator opening is set, for example, to the accelerator opening corresponding to the rate of increase in output torque that generates 0.1 G in 1 second from a shift operation from the N range to another range. can do. The accelerator opening corresponding to the rate of increase in output torque that generates 0.1 G per second can be set to, for example, 20%. Further, the second predetermined value α2 may be set to a value lower than the first predetermined value α1, for example, set to a value obtained by adding the play of the accelerator pedal 25 to the accelerator opening degree of 0% (for example, 5%). be able to.

Regarding the predetermined value of the accelerator opening degree for starting the output increase rate reduction control, in the present disclosure, a second predetermined value α2 for terminating the control is set separately from the first predetermined value α1 for starting the control. The second predetermined value α2 is the accelerator opening degree that ends (cancels) the output increase rate reduction control that has already started, for example, the degree to which the driver depresses the accelerator pedal 25 upon recognizing the start of the output increase rate reduction control. In the case where, for example, the second predetermined value α2 is weakened, this second predetermined value α2 becomes the reference value for terminating the control. The lower the value of the second predetermined value α2, the more reliably the output increase rate reduction control will be carried out to the end, which is advantageous in preventing the driver from feeling uncomfortable when accelerating and preventing accidents in the unlikely event that the wrong pedal is pressed. It is thought that.

Here, if the predetermined value of the accelerator opening that starts the output increase rate reduction control is the same as the predetermined value that ends the control, it would be too difficult to reliably implement the output increase rate reduction control. If the set predetermined value is too low, the output increase rate reduction control will be started even though the driver requests early acceleration, which will often lead to driver dissatisfaction. Therefore, the predetermined value of the accelerator opening degree that starts the output increase rate reduction control is set separately from the predetermined value that ends the control, thereby achieving both driver satisfaction and safety conditions.

FIG. 2 is a time chart showing a modification of the embodiment corresponding to FIG. A modification of the control example will be described based on the time chart of FIG. 2. In this modification, after the output increase rate reduction control is started, the accelerator opening becomes less than or equal to the second predetermined value α2, and the accelerator is shifted from the accelerator ON state to the accelerator OFF state, and the output increase rate reduction control is temporarily canceled. is assumed. The control up to the start of the output increase rate reduction control is the same as that in FIG. 1, so a description thereof will be omitted. The symbols a0', b0', c0', h0', arrows A', B', etc. in FIG. 2 correspond to the symbols a0, b0, c0, h0, arrows A, B, etc. in FIG. do.

After the accelerator is shifted to the OFF state and the output increase rate reduction control is once released, the output torque will normally be restored to the level where the output increase rate reduction control is not performed. However, if the output torque is suddenly returned to the value before the reduction correction after the output increase rate reduction control ends, this will cause discontinuous fluctuations in the output torque, leading to deterioration of ride comfort. Therefore, if the accelerator opening becomes the accelerator ON state again after the accelerator is shifted to the OFF state and the output increase rate reduction control is finished, the increase rate of the output torque is changed to the output increase rate reduction control used for the output increase rate reduction control. Additional output control is performed to set the second increase rate to be greater than the first increase rate and less than or equal to the required torque increase rate. Note that the above control may be performed when the accelerator opening is turned on again within a predetermined time. Here, the predetermined time is set to a time at which it can be recognized that the transition from the accelerator OFF state to the accelerator ON state is being continuously performed. This predetermined time can be set, for example, to 1 second, which is the limit value of the time lag that does not cause the driver to feel dissatisfied.

In this embodiment, the second increase rate of the additional output control is the normal output torque increase rate (required torque increase rate) based on the accelerator opening degree. Therefore, after the additional output control, the vehicle speed increases as indicated by d3' at the same slope as the degree of increase in vehicle speed without the output increase rate reduction control, indicated by d2' in symbol (d) in FIG. It will continue to rise. However, the second increase rate in this additional output control can also be set to a value that is less than or equal to the normal output torque increase rate (required torque increase rate) and larger than the first increase rate. This additional output control ends when the vehicle speed reaches 20 km/h.

FIG. 3 is a graph showing the relationship between vehicle speed and the rate of increase in output torque. The rate of increase in output torque is set to a value slightly higher than zero (positive value) at a vehicle speed of 0 km/h, and the minimum value of the rate of increase in output torque is set at a slight forward movement slightly higher than the vehicle speed of 0 km/h. (for example, when the vehicle speed is 2 km/h). The minimum value of the increase rate corresponds to the point h1 indicated by the symbol (h) in FIG. In this embodiment, the minimum value of the rate of increase in output torque is set to a positive value, but it may be set to zero. Furthermore, when the vehicle speed has a negative value (a driving state in which the vehicle 20 moves backwards due to its own weight on an uphill slope), the increase rate of the output torque increases as the absolute value of the vehicle speed at the time of backward movement increases. It is set. In addition, when the shift position is selected to the R range, when the vehicle speed has a negative value (driving state in which the vehicle moves forward by its own weight when reversing on a slope and parking), the vehicle speed at the time of forward movement is The larger the absolute value of is, the larger the increase rate is set. That is, the rate of increase in output torque due to the output increase rate reduction control has a minimum value when the vehicle speed is a positive value, and is a positive value when the vehicle speed is zero. Moreover, when the vehicle speed increases toward a positive value after the minimum value of the increase rate, the increase rate increases, and even when the vehicle speed decreases toward a negative value, the increase rate increases.

When the vehicle 20 backs up due to its own weight on an uphill slope, that is, when the vehicle 20 slides down when starting on a slope, the output torque increase rate is set to a positive value, so that the sliding down can be prevented quickly. can be resolved. Note that the rate of increase from zero to 0 km/h from the second predetermined speed (in the embodiment, -1 km/h (1 km/h in the reverse direction)), which is a negative value of the vehicle speed, is set as a constant value. 20 is set as a driving range that does not cause shock. In addition, the reason why the increase rate of output torque is set as a positive value at a vehicle speed of 0 km/h is because the start of an electric vehicle is generally smooth and the driver may not be aware of (experience) the fact that it is starting. Acceleration is intentionally applied at the time of starting, so that the driver can feel that his or her own vehicle 20 is starting, thereby giving the driver a sense of consideration for the safety of the surroundings.

In this embodiment, a plug-in hybrid electric vehicle is used as the vehicle 20, but the present disclosure can be applied to various electric vehicles equipped with an electric motor 22 that generates driving force using electric power. .

This application is based on Japanese Patent Application No. 2020-096173 filed on June 2, 2020, the contents of which are incorporated herein by reference.

1 Speed detection section 2 Accelerator opening detection section 3 Shift position detection section 4 Driver required torque calculation section 5 Output torque command section 10 Vehicle control device 20 Vehicle 21 Electronic control unit 22 Electric motor

Claims (5)

An electric motor is the drive source for driving,
a speed detection unit that detects vehicle speed;
an accelerator opening detection section that detects the accelerator opening;
a shift position detection section that detects the selected shift position;
a driver request torque calculation unit that calculates driver request torque based on the accelerator opening degree;
an output torque command section that commands an output torque to the electric motor,
The output torque command unit is configured to control when the shift position is switched from a neutral range to another range in an accelerator ON state where the vehicle speed is less than a first predetermined speed and the accelerator opening is equal to or greater than a first predetermined value. perform output increase rate reduction control to reduce the increase rate of the output torque to a first increase rate lower than the required torque increase rate according to the driver request torque,
The output increase rate reduction control is canceled in an accelerator OFF state where the accelerator opening is less than a second predetermined value that is lower than the first predetermined value,
Due to the output increase rate reduction control, the output torque increase rate has a minimum value when the vehicle speed is a positive value, is set to a positive value when the vehicle speed is zero, and is set to a positive value when the vehicle starts. A vehicle control device that temporarily decreases the rate of increase as the vehicle speed increases, and then sets the increase rate to be larger as the vehicle speed increases. The output torque command unit is configured to control the increase rate of the output torque when the accelerator opening changes from the accelerator ON state to the accelerator OFF state and then returns to the accelerator ON state. The vehicle control device according to claim 1, wherein additional output control is performed to set the second increase rate to be greater than the first increase rate and less than or equal to the required torque increase rate. 2. The increase rate of the output torque by the output increase rate reduction control is set such that when the vehicle speed has a negative predetermined speed or less, the increase rate increases as the absolute value of the vehicle speed increases. The vehicle control device described in . An electric motor is the drive source for driving,
a speed detection unit that detects vehicle speed;
an accelerator opening detection section that detects the accelerator opening;
a shift position detection section that detects the selected shift position;
a driver request torque calculation unit that calculates driver request torque based on the accelerator opening degree;
an output torque command section that commands an output torque to the electric motor,
The output torque command unit is configured to control when the shift position is switched from a neutral range to another range in an accelerator ON state where the vehicle speed is less than a first predetermined speed and the accelerator opening is equal to or greater than a first predetermined value. perform output increase rate reduction control to reduce the increase rate of the output torque to a first increase rate lower than the required torque increase rate according to the driver request torque,
The output increase rate reduction control is canceled in an accelerator OFF state where the accelerator opening is less than a second predetermined value that is lower than the first predetermined value,
The increase rate of the output torque due to the output increase rate reduction control has a positive value when the vehicle speed is zero, and the increase rate is constant from zero to a second predetermined speed where the vehicle speed is a negative value. The vehicle control device is set to the value of . The increase rate of the output torque due to the output increase rate reduction control is set such that when the vehicle speed has a negative value equal to or less than the second predetermined speed, the increase rate increases as the absolute value of the vehicle speed increases. 4. The vehicle control device according to 4 .

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