Vehicle control device

Abstract

To provide a vehicle control device capable of suppressing an unintentional abrupt change in drive force in BOS control.SOLUTION: A vehicle control device comprises: a control unit which suppresses drive force of a drive unit at an acceleration opening when a brake pedal is operated with the acceleration opening of an acceleration pedal in a positive state in accordance with demand brake force based on brake master cylinder pressure; and a correction processing unit which corrects the demand brake force based on operation information about the brake pedal. The control unit suppresses the drive force of the drive unit based on the demand brake force corrected by the correction processing unit.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, vehicles are equipped with a brake override system (hereinafter referred to as BOS) in which a driving force of the vehicle is suppressed by a running control ECU when an accelerator pedal and a brake pedal are simultaneously depressed during running.

[0003] Patent Document 1 discloses a method for detecting a brake operation, in which when operations are performed in the order of an accelerator operation and a brake operation and lead to a simultaneous operation, the brake operation is detected by both detection by a brake switch and detection based on a master cylinder pressure, and when operations are performed in the order of a brake operation and an accelerator operation and lead to a simultaneous operation, the brake operation is detected only by detection based on the master cylinder pressure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, depending on the driver, there are cases where the vehicle continues to run after turning off only the brake pedal from a state where the accelerator pedal and the brake pedal are depressed simultaneously, and then depressing the brake pedal again to turn it on. The required braking force from the driver is read from the value of the brake master cylinder pressure after converting the depression force of the brake pedal into pressure. Therefore, even if the operation amount of the brake pedal at the time of switching between on and off is slight, a sudden change occurs in the value of the brake master cylinder pressure at the time of switching, so that the change in the required braking force at the time of switching unintentionally becomes large. For this reason, for example, when only the brake pedal is slowly changed to off from a state where the accelerator pedal and the brake pedal are depressed simultaneously, the driving force may unexpectedly return quickly or suddenly accelerate from the state where the driving force is suppressed by the BOS control, startling the driver.

[0006] An object of the present invention is to provide a vehicle control device capable of suppressing an unintentional sudden change in driving force in BOS control.

Means for Solving the Problems

[0007] To achieve the above object, a vehicle control device according to the present invention includes a control unit that suppresses the driving force of a driving unit at an accelerator opening based on a required braking force based on a brake master cylinder pressure when an operation by a brake pedal is performed while the accelerator opening of the accelerator pedal is positive, and a correction processing unit that corrects the required braking force based on operation information of the brake pedal, and the control unit suppresses the driving force of the driving unit based on the required braking force corrected by the correction processing unit.

Effects of the Invention

[0008] According to the present invention, an unintentional sudden change in driving force in BOS control can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4A

Figure 4B

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, with reference to the accompanying drawings, a vehicle control device according to an embodiment of the present invention will be described in detail.

[0011] <EMBODIMENT> FIG. 1 is a diagram showing an example of the configuration of a vehicle equipped with a vehicle control device according to an embodiment. FIG. 1 shows the configuration of a brake override system (hereinafter referred to as BOS) of a vehicle 100 in which a travel control ECU 3 drives a drive motor 4 based on operations of an accelerator pedal 1 and a brake pedal 2.

[0012] Vehicle 100 is equipped with a plurality of ECUs (Electronic Control Units). The travel control ECU 3 is an ECU for travel control equipped with the BOS function among those ECUs. Each ECU includes a microcomputer (microcontroller unit), and the microcomputer incorporates non-volatile memories such as a CPU, flash memory, and volatile memories such as DRAM (Dynamic Random Access Memory). The plurality of ECUs are connected so as to enable two-way communication by the CAN (Controller Area Network) communication protocol. Also, various sensors necessary for control are connected to each ECU, and detection signals of the connected sensors are input. Further, in addition to the detection signals input from various sensors, information necessary for control is input to each ECU from other ECUs.

[0013] The drive motor 4 is a drive motor driven by the BOS-suppressed driving force output from the travel control ECU 3. The drive motor 4 is, for example, a permanent magnet synchronous motor. The rotating shaft of the drive motor 4 is connected to the drive system. For example, the drive system includes a differential gear, and the driving force of the drive motor 4 is transmitted to the differential gear and distributed and transmitted from the differential gear to drive wheels composed of left and right front wheels or rear wheels.

[0014] In the configuration of BOS in this example, the travel control ECU 3 functions as the "control unit", and the drive motor 4 functions as the "drive unit". Note that although a motor is applied as the "drive unit" in this example, it may be other than a motor as long as it is a drive unit that applies a rotational force to the wheels.

[0015] FIG. 1 shows, as components other than the traveling control ECU 3 related to the control by BOS, an accelerator pedal opening sensor 11, a brake master cylinder 21, a brake master cylinder pressure sensor 22, a brake ECU 23, and a brake pedal force sensor 24. Note that these show an example of the components related to the control by BOS, and do not limit the components related to the control by BOS to these components. They may be appropriately modified according to the configuration of the vehicle.

[0016] Among these, the brake master cylinder 21 converts the pedaling force applied by the driver to the brake pedal 2 into hydraulic pressure and transmits it to the wheel side. The wheel side has a deceleration device that restricts the rotation of the wheel by hydraulic pressure.

[0017] The accelerator pedal opening sensor 11 measures the accelerator opening of the accelerator pedal 1.

[0018] The brake master cylinder pressure sensor 22 measures the brake master cylinder pressure (hydraulic pressure) of the brake master cylinder 21.

[0019] The brake pedal force sensor 24 measures the pedaling force applied by the driver to the brake pedal 2. For example, a pressure sensor or the like is used as the brake pedal force sensor 24 to measure the braking force. Note that the brake pedal force sensor 24 is an example of a sensor for obtaining the operation information of the brake. The operation information of the brake only needs to know the actual operation state of the brake pedal 2 when the driver steps on the brake pedal 2 or releases the stepping force. Therefore, it is not limited to the pedaling force. For example, it may be the operation amount (stroke) of the brake pedal 2 when the driver steps on the brake pedal 2 or releases the stepping force. When measuring the operation amount of the brake pedal 2, a stroke sensor for measuring the stroke may be used.

[0020] The brake ECU 23 reads the output (brake master cylinder pressure) d2 of the brake master cylinder pressure sensor 22 and the output (brake pedal force) d3 of the brake pedal force sensor 24, and outputs information indicating the required braking force corresponding to the brake master cylinder pressure (driver required braking force information) and brake pedal force information as information outputs d32 and d33 for each to the travel control ECU 3.

[0021] The travel control ECU 3 includes a driver required drive calculation unit 31 and a BOS suppression rear drive force calculation unit 32. The driver required drive calculation unit 31 calculates the driver required drive force from the accelerator opening, which is the output d1 of the accelerator pedal opening sensor 11. The BOS suppression rear drive force calculation unit 32 has a correction processing unit that corrects the required braking force based on the operation information of the brake pedal, and calculates the BOS suppression rear drive force according to the determination result of BOS suppression based on the driver required drive force information, which is the output d31 of the driver required drive calculation unit 31, the driver required braking force information from the brake ECU 23, and the brake pedal force information from the brake ECU 23. The BOS suppression rear drive force is the drive force after reflecting the necessary BOS suppression, and when BOS suppression is not required, it remains the drive force without performing BOS suppression.

[0022] BOS suppression is performed as follows, for example. In FIG. 1, first, assume that the sensor output d1 indicating the accelerator opening is positive. At this time, the driver request driving force calculation unit 31 outputs information d31 indicating a positive driver request driving force to the BOS suppression rear driving force calculation unit 32. Then, when the driver operates the brake pedal 2 while stepping on the accelerator pedal 1, the brake master cylinder pressure at that time is output from the output d2, and the brake pedal force is output from the output d3. These are respectively output as driver request braking force information and brake pedal force information from the outputs d32 and d33 of the brake ECU 23 to the BOS suppression rear driving force calculation unit 32 of the travel control ECU 3. The BOS suppression rear driving force calculation unit 32 performs BOS suppression processing based on the positive driver request driving force information, the driver request braking force information, and the brake pedal force information. For example, the BOS suppression rear driving force calculation unit 32 corrects based on the brake pedal force information to calculate the BOS suppression rear driving force, and outputs it from the output d4 to the drive motor 4. By performing correction based on the brake pedal force information in this way, sudden driving of the drive motor 4 is improved.

[0023] Subsequently, the relationship between the brake operation intentionally performed by the driver and the deviation of the vehicle's reaction will be described with reference to FIGS. 2A to 2D. FIGS. 2A to 2D are explanatory diagrams showing the relationship between the brake operation intentionally performed by the driver and the deviation of the vehicle's reaction that occurs based on the characteristics of the brake master cylinder pressure.

[0024] FIG. 2A is a diagram depicting the relationship between the brake operation and the driver request braking force based on the brake master cylinder pressure. A diagram showing changes in characteristics with the brake pedal force on the horizontal axis and the driver request braking force on the vertical axis is shown by solid and dotted lines. The arrows in FIG. 2A are added for explanation.

[0025] First, the change when the brake pedal 2 is stepped on and the stepping force of the brake pedal 2 becomes stronger while the accelerator pedal 1 is being stepped on will be described. In this case, the driver request braking force changes along the arrow B1. The relationship between the brake pedal force and the driver request braking force is linear, and the driver request braking force increases as the brake pedal force increases.

[0026] Next, consider the case (when returning to BOS) where the braking force applied to the brake pedal 2 is relaxed while the accelerator pedal 1 is being depressed. In this case, first, as shown by arrow B2, the driver-requested braking force rapidly drops, and then it becomes linear, and the driver-requested braking force decreases as the braking force decreases.

[0027] Next, consider the case where the braking force applied to the brake pedal 2 is increased again while the accelerator pedal 1 is being depressed. In this case, first, as shown by arrow B3, the driver-requested braking force rapidly increases, and then it increases along the linear arrow B1 as the braking force increases.

[0028] As described above, when the brake pedal 2 is switched between on and off, the driver-requested braking force changes rapidly. Therefore, the relationship between the braking force and the driver-requested braking force has a relationship as shown by a hysteresis curve.

[0029] For this reason, when the brake pedal 2 is switched between on and off, even if the operation amount of the brake pedal 2 is small, the driver-requested braking force changes rapidly at the initial stage of the operation. At this time, since the BOS-requested driving force (see Fig. 2D) changes suddenly, it leads to a sense of shock for the driver and deterioration of the controllability of the driving force.

[0030] Regarding this point, to explain more specifically, the requested braking force from the driver is read from the value of the brake master cylinder pressure after converting the braking force on the brake pedal 2 into pressure. Therefore, even if the operation amount of the brake pedal 2 is small when switching between on and off, a rapid change occurs in the value of the brake master cylinder pressure during the switching, and the change in the requested braking force during the switching unintentionally becomes large. The arrow B2 shown in Fig. 2A indicates a rapid change. When switching from on to off of the brake, the driver-requested braking force drops rapidly, and accordingly, the driving force instantaneously returns, so a sudden acceleration is felt. After that, as shown in Fig. 2A, the driver-requested braking force gradually drops with the same inclination as arrow B1.

[0031] Also, when the brake pedal 2 is depressed again to turn on the brake that was once turned off (BOS operation·re - entry), the driver - requested braking force also changes abruptly. The change in the driver - requested braking force at that time is indicated by arrow B3. As shown by arrow B3, in the case of brake return, when switching from off to on, the driver - requested braking force increases abruptly, and as a result, the driving force drops instantaneously, so a sudden deceleration is felt. After that, as shown in FIG. 2A, the driver - requested braking force gradually increases as indicated by arrow B1.

[0032] FIGS. 2B to 2D are diagrams for explaining the sense of shock. FIG. 2B is a diagram showing an example of the timing of the brake operation felt by the driver. FIG. 2C is a diagram showing an example of the change in the driver - requested braking force based on the master cylinder pressure. FIG. 2D is a diagram showing an example of the change in the BOS - requested driving force.

[0033] In FIG. 2B, the portion indicated by the dotted line B2 corresponds to the portion indicated by the arrow B2 in FIG. 2A. Also, in FIG. 2B, the portion indicated by the dotted line B3 corresponds to the portion indicated by the arrow B3 in FIG. 2A. That is, the dotted line B2 is the point where the driver feels the brake is turned off, and the dotted line B3 is the point where the driver feels the brake is turned on again afterwards.

[0034] As shown in FIG. 2C, in the case based on the master cylinder pressure, it can be seen that the driver - requested braking force drops abruptly at line segment B2 (corresponding to arrow B2 in FIG. 2A) and increases abruptly at line segment B3 (corresponding to arrow B3 in FIG. 2A).

[0035] The solid line shown in FIG. 2D is the change in the BOS - requested driving force in the case based on the master cylinder pressure. As shown in FIG. 2D, in the case based on the master cylinder pressure, it can be seen that the BOS - requested driving force increases abruptly at line segment B2 (corresponding to arrow B2 in FIG. 2A) and drops abruptly at line segment B3 (corresponding to arrow B3 in FIG. 2A).

[0036] As a result, when switching the brake on and off, the driving force of the drive motor changes suddenly, and the driver is startled because the driving force returns quickly or accelerates suddenly unintentionally.

[0037] On the other hand, in the vehicle control device of the present embodiment, the BOS suppression post-driving force calculation unit 32 calculates the BOS suppression post-driving force by performing correction based on the brake pedal force information, and outputs it to the drive motor 4 from the output d4. The main correction is performed at the location where the brake pedal forces of the dotted line B2 and the dotted line B3 shown in FIG. 2B are reversed in positive and negative.

[0038] In this case, the line segment B2 shown in FIG. 2D changes as shown by the dotted line A1, and the line segment B3 changes as shown by the dotted line A2. By performing correction using the brake pedal force in this way, sudden changes can be made gentle.

[0039] FIG. 3 is a flowchart showing an example of the correction process based on the brake pedal force information of the BOS suppression post-driving force calculation unit 32. First, the BOS suppression post-driving force calculation unit 32 determines whether the driver requests a positive driving force (that is, the driver-requested driving force > 0) and whether the driver-requested braking force is positive (that is, the driver-requested braking force > 0) (step S1). The fact that the driver-requested braking force is positive is equivalent to requesting a negative driving force.

[0040] If the determination in step S1 is Yes, the BOS suppression post-driving force calculation unit 32 calculates the intermediate value of the BOS required driving force from the MAP33 (see FIG. 1) (step S2). Here, the MAP33 (see FIG. 1) has a first MAP of the BOS required driving force with the driver-requested driving force and the driver-requested braking force as the X-axis and Y-axis, respectively, and a weight change amount MAP different from this MAP. The BOS required driving force of the first MAP is the value that forms the basis of the BOS suppression post-driving force. In the present embodiment, as an example, the intermediate value of the first MAP is adopted, and the correction process of the BOS required driving force is performed using the weight change amount MAP in the subsequent steps S3 and S4.

[0041] Subsequently, the BOS suppression rear driving force calculation unit 32 derives the weight change amount of the BOS required driving force using the weight change amount MAP (step S3). The weight change amount MAP shows the weight change amount in MAP with, for example, the brake operation amount and the driver required braking force on the X-axis and Y-axis respectively. The brake operation amount is the brake pedal force measured by the brake pedal force sensor 24, the stroke measured by the stroke sensor, and the like. Note that the configuration of the MAP of the weight change amount MAP will be described in detail later with reference to the image diagrams shown in FIGS. 4A and 4B.

[0042] Subsequently, the BOS suppression rear driving force calculation unit 32 calculates the weight for obtaining the current value of the BOS required driving force (step S4). The weight of the current value is calculated by the following equation (1).

[0043] Weight (current value) = Weight (previous value) + Weight change amount (however, 0 ≤ Weight (current value) ≤ 1) ···(Equation 1)

[0044] Then, the BOS suppression rear driving force calculation unit 32 obtains the BOS required driving force (current value) by the following equation (2) (step S5).

[0045] BOS required driving force (current value) = BOS required driving force (intermediate value) × Weight + BOS required driving force driver required driving force (previous value) × (1 - Weight) ···(Equation 2)

[0046] After the calculation in step S5, the BOS suppression rear driving force calculation unit 32 outputs the obtained BOS required driving force (current value) (step S6).

[0047] If the determination in step S1 is No, the BOS suppression rear driving force calculation unit 32 substitutes a fixed value for the weight change amount of the BOS required driving force (step S2-1) and proceeds to step S4. The fixed value is set to the value that changes toward the driver required torque at the highest speed without a particularly jerky feeling (minimum -1).

[0048] In this way, the BOS suppression driving force calculation unit 32 corrects based on the brake pedal force information by weight calculation to calculate the BOS suppression driving force, and outputs it to the drive motor 4 from the output d4.

[0049] FIGS. 4A and 4B are diagrams showing an example of the weight change amount MAP. The weight change amount MAP shown in FIGS. 4A and 4B is an image of the weight change amount MAP with respect to the driver's brake operation amount (horizontal axis) and the change amount of the driver's required braking force (vertical axis). The weight change amount MAP is divided into cases where the current value is smaller (see FIG. 4A) and larger (see FIG. 4B) when comparing the previous value of the BOS required driving force and the intermediate value of the BOS required driving force.

[0050] FIG. 4A is an example of the weight change amount MAP when the BOS required driving force (current value) < BOS required driving force (previous value) (during BOS operation and re-entry). FIG. 4B is an example of the weight change amount MAP when the BOS required driving force (current value) > BOS required driving force (previous value) (when returning from BOS).

[0051] The weight change amount in the region M1 of FIG. 4A is the case when the brake is depressed and the brake operation amount is small. In the MAP of the weight change amount shown in FIG. 4A, when the brake operation amount is small and the change amount of the driver's required braking force is large, the weight becomes small, and a gentle change can be applied to the intermediate value of the driver's required driving force. Also, the larger the change amount of the driver's required braking force, the stronger the gentle change can be applied.

[0052] Also, the weight change amount in the region M2 of FIG. 4A is the case when the brake is depressed and the brake operation amount is large. In the MAP of the weight change amount shown in FIG. 4A, when the brake operation amount is large, the weight becomes large, and a gentle change to the intermediate value of the driver's required driving force can be made ineffective.

[0053] The amount of weight change in region M3 of FIG. 4B is when the brake is released and the brake operation amount is large in the negative direction. In the MAP of the amount of weight change shown in FIG. 4B, when the brake operation amount is large in the negative direction, the weight increases, and it is possible to prevent a gradual change to the intermediate value of the driver required driving force.

[0054] Also, the amount of weight change in region M4 of FIG. 4B is when the brake is released and the brake operation amount is small in the negative direction. In the MAP of the amount of weight change shown in FIG. 4B, when the brake operation amount is small in the negative direction and the change amount of the driver required braking force is large in the negative direction, the weight decreases, and it is possible to cause a gradual change to the intermediate value of the driver required driving force. Also, the larger the change amount of the driver required braking force in the negative direction, the stronger the gradual change can be made effective.

[0055] In this embodiment, a mechanism is provided to add a stepping force sensor or a brake stroke sensor, etc., and to make the change amount of the BOS suppression driving force gentle with respect to the change amount of the driver required braking force when the change amount of the driver required braking force is large with respect to the driver's operation amount. For this reason, the change can be made variable with respect to the driver's operation amount, and even when the driver required braking force changes greatly when the brake is turned on and off, the BOS suppression driving force corresponding to the driver's brake operation amount can be obtained by correction.

[0056] By such control, it is possible to suppress an unexpected sudden change in the driving force in the BOS control. Therefore, the possibility of surprising the driver by the driving force returning quickly or accelerating suddenly unintentionally is reduced.

[0057] Also, the control method according to this embodiment is a better method leading to cost reduction because it is possible to improve the accuracy of the driver required braking force by adding at least one sensor for measuring the brake operation amount to the existing negative pressure brake system.

[0058] In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

Explanation of Symbols

[0059] 1 Accelerator pedal 2 Brake pedal 3 Travel control ECU 4 Drive motor 11 Accelerator pedal opening sensor 21 Brake master cylinder 22 Brake master cylinder pressure sensor 23 Brake ECU 24 Brake pedal force sensor 33 MAP 100 Vehicle

Claims

1. When an operation by the brake pedal is performed while the accelerator opening of the accelerator pedal is in a positive state, a control unit that suppresses the driving force of the driving unit at the accelerator opening based on a required braking force based on the brake master cylinder pressure; A correction processing unit that corrects the required braking force based on the operation information of the brake pedal; having; The control unit suppresses the driving force of the driving unit based on the required braking force after correction by the correction processing unit. A vehicle control device characterized by the above.

2. The correction processing unit corrects the required braking force based on the magnitude of the operation amount of the brake pedal and the change amount of the required braking force. The vehicle control device according to claim 1, characterized by the above.

3. In an operation indicating the switching between on and off of the brake pedal, when the operation amount of the brake pedal is small and the change amount of the required braking force is large, the correction processing unit corrects the required braking force so as to be small. The vehicle control device according to claim 2, characterized by the above.

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