Braking force control method and braking force control device

Abstract

This invention provides a braking force control method that can suppress the generation of braking force caused by objects falling onto the pedal. [Solution] The braking force of the vehicle is controlled based on the detected change in the pedal position of the vehicle's brake pedal. If the change in the provisional target braking force (specific parameters) per predetermined time, calculated based on the change in pedal position (detected value), exceeds the braking force change limit value (threshold) (S104 "No"), the provisional target braking force (specific parameters) is corrected in a direction that reduces the change per predetermined time, and the braking force of the vehicle is controlled based on the corrected provisional target braking force (corrected specific parameters) (S108).

Description

[Technical Field]

[0001] This disclosure relates to a braking force control method and a braking force control device. [Background technology]

[0002] Conventionally, force-sensing brake systems have been proposed in which the brake pedal and brake actuator are not mechanically connected (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-38286 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in the brake system described in Patent Document 1, for example, if an object falls onto the brake pedal and a load is applied to the brake pedal by the falling object, that load is detected as pedaling force, which can generate a large braking force in the vehicle and potentially cause the vehicle to brake suddenly. This disclosure aims to provide a braking force control method and a braking force control device that can suppress the generation of braking force due to objects falling onto the pedal. [Means for solving the problem]

[0005] A braking force control method according to one aspect of the present disclosure controls the braking force of a vehicle based on a detected value of the change in pedal posture of the vehicle's brake pedal or the pedal force applied to the brake pedal. If the amount of change per predetermined time of the detected value or a specific parameter calculated based on the detected value exceeds a threshold, the detected value or specific parameter is corrected in a direction that reduces the amount of change per predetermined time, and the braking force is controlled based on the corrected detected value or specific parameter. [Effects of the Invention]

[0006] According to this disclosure, it is possible to provide a braking force control method and a braking force control device that can suppress the generation of braking force due to objects falling onto the pedal. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the overall configuration of the braking force control device according to the first embodiment. [Figure 2] This diagram shows the functional configuration of the pedal device and brake controller. [Figure 3] This diagram shows the operation of the brake controller according to the first embodiment. [Figure 4] This diagram shows the target braking force, etc., when the brake pedal is pressed. [Figure 5] This figure shows the relationship between the amount of change in pedal position and the hypothetical target braking force. [Figure 6] This figure shows the relationship between the amount of change in pedal position and the limit value for the amount of change in braking force. [Figure 7] This diagram shows the target braking force, etc., when an object falls onto the brake pedal. [Figure 8] This diagram shows the target braking force, etc., when an object falls in a comparative example. [Figure 9] This figure shows the relationship between the amount of change in pedal position and the limit value for the amount of change in braking force. [Figure 10] This diagram shows the target braking force, etc., when the brake pedal is pressed in the modified example (1). [Figure 11] This diagram shows the operation of the brake controller in modified example (2). [Figure 12] This diagram shows the target braking force, etc., when the brake pedal is pressed in the modified example (2). [Figure 13] This diagram shows the target braking force, etc., when the brake pedal is pressed in the comparative example. [Figure 14] This figure shows the functional configuration of the pedal device and the like in the second embodiment. [Figure 15] This figure shows the operation of the brake controller in the second embodiment. [Figure 16] This diagram shows the target braking force, etc., when the brake pedal is pressed. [Figure 17] This diagram shows the relationship between pedal force and the limit value for the amount of change in pedal force. [Figure 18] This figure shows the operation of the brake controller in the second embodiment. [Figure 19] This diagram shows the relationship between pedal stroke and the limit value of the stroke change. [Figure 20] This figure shows the operation of the brake controller in the second embodiment. [Figure 21] This diagram shows the relationship between virtual pedal force and hypothetical target braking force. [Figure 22] This is a diagram showing the relationship between virtual stroke and hypothetical target braking force. [Figure 23] This diagram shows the target braking force, etc., when an object falls onto the brake pedal. [Figure 24] This diagram shows the target braking force, etc., when an object falls in a comparative example. [Modes for carrying out the invention]

[0008] The embodiments of this invention will be described in detail below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of the present invention described below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the structure, arrangement, etc., of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims. (First Embodiment) In the first embodiment, as shown in Figure 1, an example is given in which the braking force control method and braking force control device of this disclosure are applied to a braking force control device 1 that controls the braking force of a vehicle. Figure 1 is a diagram showing the overall configuration of the braking force control device 1 according to the first embodiment. The braking force control device 1 according to the first embodiment shown in Figure 1 constitutes a brake-by-wire type brake mechanism. As shown in Figure 1, the braking force control device 1 includes a pedal device 2 and a brake device 3.

[0009] The pedal device 2 includes a housing 9, a brake pedal 10, an operation rod 11, and a stroke simulator 12. Figure 1 illustrates a case where the pedal device 2 is an organ-type device located at the driver's feet and operated by the driver. The housing 9 is fixed to the floor of the driver's seat. The brake pedal 10 also has a pedal arm 13 and a pedal pad 14. The lower end of the pedal arm 13 is rotatably supported by the housing 9 and is rotatable around its lower end. The pedal pad 14 is formed on the upper end of the pedal arm 13 and can be pressed by the driver's foot when pressing the brake pedal 10. As a result, when the pedal pad 14 is pressed, the brake pedal 10 tilts the upper end of the pedal arm 13 toward the floor.

[0010] The operation rod 11 has one end connected to the vertical center of the pedal arm 13 and the other end connected to the input section 16 (described later) of the stroke simulator 12. As a result, the operation rod 11 transmits the pedaling force from the brake pedal 10 to the stroke simulator 12 due to the driver's pressing operation, and also transmits the reaction force (pedal reaction force) generated by the stroke simulator 12 in response to that pedaling force back to the brake pedal 10. The stroke simulator 12 comprises a case 15, an input section 16, an elastic member 17, and a fixed section 18. The case 15 is a cylindrical member fixed to the housing 9 and housing the input section 16, the elastic member 17, and the fixed section 18. The input section 16 is connected to the operation rod 11 and the elastic member 17. As a result, when pedal force is transmitted from the operation rod 11, the input section 16 moves along the case 15 and transmits the pedal force during the brake pedal 10 pressing operation to the elastic member 17. The elastic member 17 is compressed along the longitudinal direction of the case 15 when pedal force is transmitted from the input section 16. The fixed section 18 is formed at the bottom of the case 15 and receives the reaction force when the elastic member 17 is compressed.

[0011] Furthermore, as shown in Figure 2, the pedal device 2 includes a pedal input detection unit 19 (or "detection unit" in a broader sense), a signal calculation unit 20, and a signal output unit 21. Figure 2 is a diagram showing the functional configuration of the pedal device 2 and the brake controller 8. The pedal input detection unit 19 detects the amount of change in the pedal posture Δ of the brake pedal 10 and generates a detected value. As the pedal input detection unit 19, for example, a sensor can be used that is positioned on the rotation axis of the lower end of the pedal arm 13 and detects the rotation angle of the pedal arm 13 on the rotation axis as the amount of change in the pedal posture Δ of the brake pedal 10. Alternatively, a sensor can be used that is positioned on the input unit 16 of the stroke simulator 12 and detects the amount of movement of the input unit 16 within the case 15 as the amount of change in pedal posture Δ. The detected value (amount of change in pedal posture Δ) is converted into an electrical signal by the signal calculation unit 20 and output to the brake controller 8 via the signal output unit 21.

[0012] As shown in Figure 1, the brake system 3 includes wheel cylinders 22, 23, 24, and 25, a main brake system 26, and a sub-brake system 27. Each of the wheel cylinders 22-25 is positioned on each wheel of the vehicle and is fitted with a brake pad. The main brake system 26 supplies brake fluid to each wheel cylinder 22-25 based on a control signal output from the main brake controller 28, increasing the hydraulic pressure in each wheel cylinder 22-25. The sub-brake system 27 also supplies brake fluid to each wheel cylinder 22-25 based on a control signal output from the sub-brake controller 29, increasing the hydraulic pressure in each wheel cylinder 22-25. This presses the brake pads of the wheel cylinders 22-25 against the brake disc, generating braking force in the vehicle. For example, a VDC system may be used as the sub-brake system 27. Furthermore, the brake device 3 has a brake controller 8 (broadly speaking, a "control unit"). The brake controller 8 has a main brake controller 28 and a sub-brake controller 29. The main brake controller 28 and the sub-brake controller 29 have a microcontroller, a memory device, a drive circuit, etc. The main brake controller 28 outputs a control signal to the main brake device 26 based on the signal output from the pedal device 2. The sub-brake controller 29 also outputs a control signal to the sub-brake device 27 based on the signal output from the pedal device 2. The control signals output from the main brake controller 28, etc. are obtained, for example, by the main brake controller 28 and the sub-brake controller 29 executing a program stored in the memory device using a microcontroller to realize each function of the brake controller 8 described below.

[0013] Next, we will explain in detail each function that the brake controller 8 provides. The brake controller 8, through the execution of a program by the microcontroller, realizes the functions of the signal input unit 31, the braking force calculation unit 32, and the braking force output unit 33, as shown in Figure 2. The signal input unit 31 acquires the signal output from the pedal device 2 and obtains the pedal posture change amount Δ indicated by the acquired signal (S101 in Figure 3). Figure 3 is a diagram showing the operation of the brake controller 8 of the first embodiment. Here, if the driver slowly presses down the brake pedal 10, the pedal posture change amount Δ increases gradually as shown in Figure 4. Figure 4 shows the target braking force X when the driver slowly presses down the brake pedal 10. * This figure shows new, etc. Next, the braking force calculation unit 32 calculates a provisional target braking force of the vehicle (hereinafter also called "provisional target braking force Xnew") based on the acquired pedal posture change amount Δ (S102 in Figure 3). One method for calculating the provisional target braking force Xnew is to increase the provisional target braking force Xnew as the pedal posture change amount Δ is larger, as shown in Figure 5. Figure 5 is a diagram showing the relationship between the pedal posture change amount Δ and the provisional target braking force Xnew. As shown in Figure 4, if the increase in the pedal posture change amount Δ is gradual, the provisional target braking force Xnew also increases gradually.

[0014] Subsequently, the braking force calculation unit 32 calculates an upper limit of the change amount of the temporary target braking force Xnew per predetermined time (hereinafter also referred to as "braking force change amount limit value Y". Y>0) (S103 in FIG. 3). As the predetermined time, for example, the time (constant time) from when the previous temporary target braking force Xnew (hereinafter also referred to as "previous temporary target braking force Xold") was calculated until the current temporary target braking force Xnew is calculated in S102 can be adopted. As a method for calculating the braking force change amount limit value Y (broadly "threshold value"), for example, as shown in FIG. 6, a method of increasing the braking force change amount limit value Y as the pedal attitude change amount Δ (detection value) is larger can be adopted. FIG. 6 is a diagram showing the relationship between the pedal attitude change amount Δ and the braking force change amount limit value Y. In FIG. 6, in a range where the pedal attitude change amount Δ is sufficiently large, a case where the braking force change amount limit value Y does not increase and becomes a constant value even when the pedal attitude change amount Δ increases is exemplified. As shown in FIG. 4, if the increase in the pedal attitude change amount Δ is gentle, the braking force change amount limit value Y also increases gently. Subsequently, the braking force calculation unit 32 determines whether the absolute value of the difference between the current temporary target braking force Xnew calculated in S102 and the previous temporary target braking force Xold is greater than the braking force change amount limit value Y (|Xnew - Xold|>Y) (S104 in FIG. 3). That is, it is determined whether the temporary target braking force Xnew has increased or decreased rapidly.

[0015] And, as shown in FIG. 4, if the change in the temporary target braking force Xnew is gentle, it is determined that |Xnew - Xold|≤Y ( "No" in S104 of FIG. 3), and the braking force calculation unit 32 determines whether the previous temporary target braking force Xold is greater than the previous target braking force X * new (hereinafter also referred to as "previous target braking force X * old") (S105 in FIG. 3). That is, it is determined whether the increase rate of the previous temporary target braking force Xold is high and the previous target braking force X * old has been reduced. And when it is determined that X * old = Xold ( "No" in S105 of FIG. 3), the current temporary target braking force Xnew is set as the target braking force X * new, and the braking force output unit 33 applies the target braking force X * new to the vehicle *Output a control signal that generates the same braking force as new to the main braking device 26 and the sub - braking device 27 of the braking device 3 (S106 in FIG. 3). Thereby, the main braking device 26 and the sub - braking device 27 generate a braking force corresponding to the pedal attitude change amount Δ in the vehicle. That is, the braking force of the vehicle is controlled based on the detected value of the pedal attitude change amount Δ. Thereafter, by repeating the flow of S101 - S106 above from the acquisition of the pedal attitude change amount Δ, the generation of the braking force corresponding to the pedal attitude change amount Δ is repeatedly executed.

[0016] On the other hand, when the driver is not stepping on the brake pedal 10, if an object falls on the brake pedal 10 and a large load is instantaneously applied to the brake pedal 10 by the falling object, and as shown in FIG. 7, it is assumed that the pedal attitude change amount Δ increases rapidly. Then, the temporary target braking force Xnew also increases rapidly (S102 in FIG. 3), and the braking force change amount limit value Y also increases rapidly (S103 in FIG. 3). And when the absolute value of the difference between the current temporary target braking force Xnew and the previous temporary target braking force Xold becomes larger than the braking force change amount limit value Y (S104 “Yes” in FIG. 3), the braking force calculation unit 32 determines whether the current temporary target braking force Xnew is larger than the previous temporary target braking force Xold (Xnew - Xold>0) (S107 in FIG. 3). That is, it is determined whether the temporary target braking force Xnew is in an increasing trend. And when it is determined that Xnew - Xold>0 (S106 “Yes” in FIG. 3), the target braking force X * new is set as the value obtained by adding the braking force change amount limit value Y to the previous target braking force X * old (X * old + Y) (S108 in FIG. 3). Thereby, the increase amount (increase speed) of the target braking force X * new per unit time is limited, and as shown in FIG. 7, the increase of the target braking force X * new becomes gentle. That is, when the change amount per unit time of the temporary target braking force Xnew (specific parameter calculated based on the detected value) calculated based on the pedal attitude change amount Δ exceeds the braking force change amount limit value Y (threshold value), the temporary target braking force Xnew is corrected in the direction of decreasing the change amount per unit time, and the corrected temporary target braking force Xnew is used as the target braking force X* Set it to new. Specifically, the correction of the temporary target braking force Xnew is performed such that the amount of change per predetermined time becomes the braking force change amount limit value Y (threshold value). Subsequently, the braking force output unit 33 generates a control signal for generating the same braking force as the set target braking force X * new in the vehicle and outputs it to the main braking device 26 and the sub-braking device 27 of the braking device 3 (S108 in FIG. 3). Thereby, the main braking device 26 and the sub-braking device 27 generate a gradually increasing braking force in the vehicle. That is, the braking force of the vehicle is controlled based on the set target braking force X * new, that is, the corrected temporary target braking force Xnew (corrected specific parameter). Thereafter, by repeating the flows of S101 to S104, S107, and S108 from the acquisition of the pedal attitude change amount Δ, the generation of the gradually increasing braking force is repeatedly executed.

[0017] Also, after an object has fallen onto the brake pedal 10 and the falling object is immediately removed from the brake pedal 10, assume that the pedal attitude change amount Δ has decreased rapidly as shown in FIG. 7. Then, the temporary target braking force Xnew also decreases rapidly (S102 in FIG. 3), and it is determined that the current temporary target braking force Xnew is smaller than the previous temporary target braking force Xold (Xnew - Xold < 0) ( "No" in S107 in FIG. 3). That is, it is determined that the temporary target braking force Xnew is in a decreasing trend. Subsequently, the braking force calculation unit 32 determines that the previous temporary target braking force Xold is larger than the previous target braking force X * old (X * old < Xold) ( "Yes" in S105 in FIG. 3), and as the target braking force X * new, the minimum value (MIN(X * old + Y, Xnew)) of the value obtained by adding the braking force change amount limit value Y to the previous target braking force X * old (X * old + Y) and the current temporary target braking force Xnew is set (S109 in FIG. 3). Thereby, as shown in FIG. 7, the gentle increase of the target braking force X * new is continued, and the target braking force X *The difference between new and the provisional target braking force Xnew gradually decreases. The braking force output unit 33 supplies the vehicle with the target braking force X * A control signal that generates the same braking force as "new" is output to the main brake device 26 and sub brake device 27 of the brake device 3 (S109 in Figure 3).

[0018] The target braking force X mentioned above * The difference between new and the provisional target braking force Xnew is repeatedly reduced, and the previous target braking force X * When old and the previous provisional target braking force Xold become equal, (X * old = Xold. (Figure 3, S105 "No"), target braking force X * The provisional target braking force Xnew is set as new, and the braking force output unit 33 outputs the target braking force X to the vehicle. * A control signal that generates the same braking force as new is output to the main brake unit 26 and sub-brake unit 27 of the brake unit 3 (S106 in Figure 3). As a result, the main brake unit 26 and sub-brake unit 27 generate a braking force in the vehicle that corresponds to the pedal posture change amount Δ, that is, a braking force that decreases quickly. In other words, when the pedal posture change amount Δ (detected value) is decreasing, the braking force of the vehicle is controlled based on the provisional target braking force Xnew (specific parameter) that has not been corrected. Subsequently, the flow from S101 to S104, S107, S105 and S106 described above is repeated from the acquisition of the pedal posture change amount Δ, thereby repeatedly generating a braking force that decreases quickly.

[0019] (Effects of the first embodiment) (1) Here, as a comparative example, target braking force X * Let's consider the case where we always use a provisional target braking force Xnew as new. In this case, for example, suppose an object falls onto the brake pedal 10, and a large load is instantaneously applied to the brake pedal 10 by the falling object, causing the pedal posture change amount Δ to increase rapidly, as shown in Figure 8. Then, the provisional target braking force Xnew also increases rapidly, and the target braking force X * The new force also increases rapidly, potentially causing the vehicle to brake suddenly. Figure 8 shows the target braking force X when an object falls onto the brake pedal 10 in a comparative example. *This is a diagram showing new, etc. In contrast, in the first embodiment, the braking force of the vehicle is controlled based on the detected value of the change in pedal posture Δ of the vehicle's brake pedal 10 (target braking force X). * new = k·Δ). Then, if the change in the provisional target braking force Xnew (specific parameter), calculated based on the pedal posture change amount Δ (detected value), per predetermined time exceeds the braking force change limit value Y (threshold) (Xnew - Xold > Y), the provisional target braking force Xnew (specific parameter) is corrected in the direction that the change per predetermined time becomes smaller, and the corrected provisional target braking force Xnew (corrected specific parameter. Target braking force X * The braking force of the vehicle is controlled based on new = Xold + Y). Specifically, the system is configured to include a limiter that sets an upper limit on the rate of change of the provisional target braking force Xnew. This makes it possible to suppress the generation of a sudden braking force due to a rapid increase in the pedal posture change amount Δ, for example, when an object falls onto the brake pedal 10 and a large load is instantaneously applied to the brake pedal 10 by the falling object, as shown in Figure 7.

[0020] (2) In the first embodiment, the braking force change limit value Y (threshold) is increased as the pedal posture change amount Δ (detected value) increases. This makes it possible to suppress the occurrence of sudden braking of the vehicle when a large load is instantaneously applied to the brake pedal 10 by a falling object. Also, when the driver applies a large pedal force to the brake pedal 10 gradually, the effect of the limiter can be weakened, and braking can be performed in accordance with the driver's pedaling operation.

[0021] (3) As a comparative example, consider the case where the braking force of the vehicle is controlled based on the corrected provisional target braking force Xnew (corrected specific parameter) even when the pedal posture change amount Δ is decreasing. In this case, for example, if an object falls onto the brake pedal 10 and the driver removes the object from the brake pedal 10, the target braking force X will be as shown in Figure 7. * The new effect is gradually reduced, and it takes a long time for the braking force caused by the falling object to wear off. In contrast, in the first embodiment, when the pedal posture change amount Δ (detected value) is decreasing, the braking force of the vehicle is controlled based on a provisional target braking force Xnew (specific parameter) that has not been corrected. As a result, for example, when the driver removes a fallen object from the brake pedal 10, the target braking force X * The new design allows for a rapid reduction in braking force caused by falling objects, shortening the time it takes for the vehicle to complete braking.

[0022] (4) In the first embodiment, based on the pedal posture change amount Δ (detected value), the provisional target braking force Xnew of the vehicle is calculated as the above specific parameter, and based on the calculated provisional target braking force Xnew, the target braking force X * Set new, and set target braking force X * Based on new, the vehicle's braking force is controlled. Furthermore, if the rate of change of the provisional target braking force Xnew per predetermined time exceeds the braking force change limit value Y (threshold), the provisional target braking force Xnew is corrected in a direction that reduces the rate of change per predetermined time, and the corrected provisional target braking force Xnew is set. This allows the target braking force X * The new configuration performs limiter processing calculations. Therefore, the target braking force X * Since it is only necessary to perform the limiter processing calculation on `new`, compared to performing the limiter processing calculation for each sensor detection value, the program size can be reduced and the calculation speed can be shortened, for example, when there are many sensors (pedal input detection units 19).

[0023] (modified version) (1) In the first embodiment, an example was shown in which the braking force change limit value Y is changed based on the pedal posture change amount Δ, but other configurations can also be adopted. For example, as shown in Figure 9, the braking force change limit value Y may be set to a predetermined constant value regardless of the magnitude of the pedal posture change amount Δ. Figure 9 is a diagram showing the relationship between the pedal posture change amount Δ and the braking force change limit value Y. In Figure 9, an example is shown in which the constant value of the braking force change limit value Y is made smaller than the minimum value of the braking force change limit value Y shown in Figure 6. In this case, for example, if the driver slowly presses down on the brake pedal 10, and as shown in Figure 10, even if the increase in the pedal posture change amount Δ is gradual, the target braking force X per predetermined time * The amount of increase (rate of increase) of new is reduced by the braking force change limit value Y. Figure 10 shows the target braking force X when the driver slowly presses the brake pedal 10 in modified example (1). * This is a diagram showing new, etc.

[0024] (2) Alternatively, as shown in Figures 11 and 12, for example, the braking force change limit value Y (threshold) may be configured to increase as the elapsed time from the start of pressing the brake pedal 10 increases. Figure 11 is a diagram showing the operation of the brake controller 8 in modified example (2). Figure 12 shows the target braking force X in modified example (2) when the driver slowly presses the brake pedal 10. * This figure shows new, etc. In Figure 11, an example is shown where S201 to S203 are executed simultaneously with S102 and S103, and S204 to S205 are executed between S103 and S104. Through S201 to S206, the braking force calculation unit 32 first determines whether the pedal posture change amount Δ is "0" (S201 in Figure 11). Then, if the pedal posture change amount Δ is "0" (S201 "Yes" in Figure 11), the braking force calculation unit 32 sets the variable N to "0" (S202 in Figure 11). On the other hand, if the pedal posture change amount Δ is not "0" (S201 "No" in Figure 11), "1" is added to the variable N (S203 in Figure 11). As a result, when the brake pedal 10 is pressed down, the variable N is counted up, and the elapsed time from the start of pressing the brake pedal 10 is counted.

[0025] Next, the braking force calculation unit 32 determines whether the variable N is greater than a predetermined threshold T (constant) (S204 in Figure 11). If it determines that the variable N is less than or equal to the threshold T (S204 "No" in Figure 11), it sets the braking force change limit value Y calculated in S103 as the braking force change limit value Y (S205 in Figure 11). In calculating the braking force change limit value Y, a method is adopted in which the braking force change limit value Y is increased as the pedal posture change amount Δ shown in Figure 6 is larger. On the other hand, if the braking force calculation unit 32 determines that the variable N is greater than the threshold T (S204 "Yes" in Figure 11), it adds "1" to the previous braking force change limit value Y (hereinafter also called "previous braking force change limit value Yold") as the braking force change limit value Y (S206 in Figure 11). This allows, for example, when the driver depresses the brake pedal 10 and the pedal load is continuously applied, the limit value Y for the amount of change in braking force can be increased, and the target braking force X can be increased. * The upper limiter on the rate of change of new can be weakened. Therefore, it does not interfere with the driver's braking of the vehicle. In S206, the upper limit of the braking force change limit value Y is limited by the upper limit value L. Here, as a comparative example, consider the case where, in the configuration shown in Figure 11, the braking force change limit value Y is set to a predetermined constant value, as shown in Figure 9. In this case, even when the driver applies a large pedal force to the brake pedal 10 gradually, the increase in the target braking force Xnew is suppressed, as shown in Figure 13. In contrast, in this modified example (2), as shown in Figure 6, the braking force change limit value Y is increased as the pedal posture change amount Δ increases, thereby weakening the effect of the limiter and enabling braking in accordance with the driver's pedal operation. (3) In the first embodiment, an example was shown in which the pedal posture change amount Δ was used as the detected value, but other configurations can also be adopted. For example, the part in the first embodiment in which the pedal posture change amount Δ was used may be configured to use the pedal force T applied to the brake pedal 10.

[0026] (Second Embodiment) Next, a braking force control device 1 according to the second embodiment of this disclosure will be described. The overall configuration of the braking force control device 1 according to the second embodiment is the same as in Figure 1, so it is not shown. Figure 14 is a diagram showing the functional configuration of the pedal device 2 and brake controller 8 of the second embodiment. In Figure 14, the same reference numerals are used for parts corresponding to Figure 2, and redundant explanations are omitted. In the braking force control device 1 according to the second embodiment, the target braking force X * In setting this, the pedal force T is considered in addition to the amount of change in posture Δ (also called "stroke S" in the second embodiment) applied to the brake pedal 10, which is different from the braking force control device 1 according to the first embodiment. As shown in Figure 14, the pedal device 2 of the second embodiment has a stroke sensor 34 (broadly defined as a "detection unit") and a pedal force sensor 35 (broadly defined as a "detection unit"). The stroke sensor 34 detects the stroke S of the brake pedal 10 and generates a detected value. As the stroke sensor 34, for example, a sensor can be used that is placed in the input section 16 of the stroke simulator 12 and detects the amount of movement of the input section 16 within the case 15 as the pedal stroke S. The detected value (pedal stroke S) is converted into an electrical signal by the first signal calculation unit 36 ​​and output to the brake controller 8 via the first signal output unit 37. The pedal force sensor 35 detects the pedal force T applied to the brake pedal 10 and generates a detected value. For example, the pedal force sensor 35 is positioned at the connection point between the pedal arm 13 and the operation rod 11, and detects the load or stress acting on the connection point as the pedal force T applied to the brake pedal 10. The detected value (pedal force T) is converted into an electrical signal by the second signal calculation unit 38 and output to the brake controller 8 via the second signal output unit 39.

[0027] Next, we will explain in detail each function implemented by the brake controller 8 of the second embodiment. The brake controller 8, through the execution of a program by the microcontroller, realizes the functions of the signal input unit 31, the braking force calculation unit 32, and the braking force output unit 33, as shown in Figure 14. The signal input unit 31 has a first signal input unit 40 and a second signal input unit 41. The first signal input unit 40 acquires the signal output from the first signal output unit 37 and obtains the pedal force T indicated by the acquired signal (S301 in Figure 15). Figure 15 is a diagram showing the operation of the brake controller 8 of the second embodiment. Here, if the driver slowly presses down on the brake pedal 10, the pedal force T increases gradually, as shown in Figure 16. Figure 16 shows the target braking force X when the driver slowly presses down on the brake pedal 10. * This figure shows new etc. Next, the braking force calculation unit 32 calculates a limit value YT for the amount of change in pedal force T per predetermined time (hereinafter also called the "pedal force change limit value YT"; YT>0) (S302 in Figure 15). As the predetermined time, for example, the time (a fixed time) from when the previous pedal force T is obtained until when the current pedal force T is obtained can be used.

[0028] Furthermore, as a method for calculating the pedal force change limit value YT (broadly speaking, the "threshold"), for example, as shown in Figure 17, a method can be adopted in which the pedal force change limit value YT increases as the pedal force T (detected value) increases. Figure 17 is a diagram showing the relationship between pedal force T and the pedal force change limit value YT. In Figure 17, within a sufficiently large range of pedal force T, even if the pedal force T increases, the pedal force change limit value YT does not increase but remains at a constant value (maximum value). As shown in Figure 16, if the increase in pedal force T is gradual, the pedal force change limit value YT also increases gradually. Next, the braking force calculation unit 32 determines whether the absolute value of the difference between the current pedal force T obtained in S301 and the pedal force T obtained one step earlier (hereinafter also called "previous pedal force Told") is greater than the pedal force change limit value YT (|T-Told|>YT) (S303 in Figure 15). In other words, it determines whether the pedal force T has increased or decreased sharply. Then, as shown in FIG. 16, when the change in the pedal depressing force T is gentle and it is determined that |T - Told| ≦ YT (No in S303 of FIG. 15), the braking force calculation unit 32 calculates the virtual depressing force T * (hereinafter also referred to as the "previous virtual depressing force T * old"). Then, it determines whether the previous pedal depressing force Told is greater than the previous virtual depressing force T * old (T * old < Told) (S304 of FIG. 15). That is, it determines whether the increase rate of the previous pedal depressing force T was high and the previous virtual depressing force T * was reduced. And when it is determined that T * old = Told (No in S304 of FIG. 15), the braking force calculation unit 32 sets the current pedal depressing force T as the virtual depressing force T * (T

[0029] = T. S305 of FIG. 15).Simultaneously, the second signal input unit 41 acquires the signal output from the second signal output unit 39 and obtains the pedal stroke S indicated by the acquired signal (S401 in Figure 18). Figure 18 is a diagram showing the operation of the brake controller 8 of the second embodiment. As shown in Figure 16, if the driver slowly presses down on the brake pedal 10, the pedal stroke S increases gradually. Next, the braking force calculation unit 32 calculates the limit value YS of the amount of change of the pedal stroke S per predetermined time (hereinafter also called the "stroke change limit value YS"; YS > 0) (S402 in Figure 18). As the predetermined time, for example, the time (a certain period of time) from when the previous pedal stroke S is acquired until when the current pedal stroke S is acquired can be used. As a method for calculating the stroke change limit value YS, for example, as shown in Figure 19, a method can be adopted in which the stroke change limit value YS increases as the pedal stroke S (detected value) increases. Figure 19 is a diagram showing the relationship between the pedal stroke S and the stroke change limit value YS. Figure 19 illustrates a case where, within a sufficiently large range of pedal stroke S, the stroke change limit value YS does not increase even when the pedal stroke S increases, but remains constant (maximum value). As shown in Figure 16, if the increase in pedal stroke S is gradual, the stroke change limit value YS also increases gradually. Next, the braking force calculation unit 32 determines whether the absolute value of the difference between the current pedal stroke S obtained in S401 and the pedal stroke S obtained immediately before (hereinafter also referred to as "previous pedal stroke Sold") is greater than the stroke change limit value YS (|S-Sold|>YS) (S403 in Figure 18). That is, it determines whether the pedal stroke S has increased or decreased sharply. Then, if the change in pedal stroke S is gradual, it is determined that |S-Sold|≦YS (S403 "No" in Figure 18), and the braking force calculation unit 32 calculates the previous virtual stroke S * (The following is "Previous virtual stroke S") * Is the previous pedal stroke Sold greater than (S) *Determine old<Sold) (S404 in FIG. 18). That is, determine whether the increase rate of the previous pedal stroke S was high and the previous virtual stroke S * was reduced. And when S * is determined to be old = Sold ( "No" in S404 of FIG. 18), set the current pedal stroke S * as the virtual stroke S (S405 in FIG. 18).

[0030] According to the above flow, when the virtual pedaling force T * and the virtual stroke S * are set (S305 in FIG. 15, S405 in FIG. 18), the braking force calculation unit 32 calculates the target braking force X * and the virtual stroke S * based on the set virtual pedaling force T * new (S501 - S503 in FIG. 20). As a method for calculating the target braking force X * new, for example, as shown in FIGS. 21 and 22, the larger the virtual pedaling force T * , the larger the virtual target braking force X T is set, and the larger the virtual stroke S * , the larger the virtual target braking force X S is set. A method of setting the target braking force X T new as the value obtained by adding the set virtual target braking force X S and the virtual target braking force X * can be mentioned. FIG. 21 is a diagram showing the relationship between the virtual pedaling force T * and the virtual target braking force X T . Also, FIG. 22 is a diagram showing the relationship between the virtual stroke S * and the virtual target braking force X S . Subsequently, the braking force output unit 33 outputs a control signal for generating the same braking force as the target braking force X * new to the main brake device 26 and the sub - brake device 27 (S504 in FIG. 20). Thereby, the main brake device 26 and the sub - brake device 27 generate a braking force corresponding to the virtual pedaling force T * (= pedal pedaling force T) and the virtual stroke S *A braking force is generated in the vehicle according to the pedal stroke S. That is, the braking force of the vehicle is controlled based on the detected values ​​of pedal force T and pedal stroke S. Subsequently, the above flow from S301 to S504 is repeated after acquiring the pedal force T and pedal stroke S, thereby repeatedly generating the braking force according to the pedal force T and pedal stroke S.

[0031] On the other hand, suppose an object falls onto the brake pedal 10 when the driver is not pressing it, and a large load is instantaneously applied to the brake pedal 10 by the falling object, causing the pedal force T to increase rapidly as shown in Figure 23. Then the pedal force change limit value YT also increases rapidly (S302 in Figure 15). When the absolute value of the difference between the current pedal force T and the previous pedal force Told becomes larger than the pedal force change limit value YT (S303 "Yes" in Figure 3), the braking force calculation unit 32 determines whether the current pedal force T is greater than the previous pedal force Told (T-Told>0) (S306 in Figure 15). That is, it determines whether the pedal force T is on an increasing trend. When it is determined that T-Told>0 (S306 "Yes" in Figure 15), the virtual pedal force T * As for the previous virtual pedaling force T * The value obtained by adding the pedal force change limit value YT to old (T * Set old + YT) (S307 in Figure 15). This sets the virtual pedaling force T per predetermined time. * The amount of increase (rate of increase) is limited, and as shown in Figure 23, the virtual pedal force T * The increase becomes gradual. That is, if the amount of change in pedal force T (detected value) per predetermined time exceeds the pedal force change limit value YT (threshold), the pedal force T is corrected in a direction that reduces the amount of change per predetermined time, and the corrected pedal force T is called the virtual pedal force T. * Specifically, the correction of the pedal force T is performed so that the amount of change per predetermined time becomes the pedal force change limit value YT (threshold). Subsequently, by repeating the above flow S301~S303, S306 and S307 from the acquisition of the pedal force T, the above gradually increasing virtual pedal force T is obtained. *The calculation of * is executed multiple times. Similarly, the flows of S401 to S403, S406, and S407 in FIG. 18 are repeated, and as shown in FIG. 23, the virtual stroke S * that gradually increases * is calculated multiple times. Then, according to the above flow, the virtual braking force T * and the virtual stroke S * are set, and the braking force calculation unit 32 calculates the target braking force X * new based on the set virtual braking force T * and the virtual stroke S * (S501 to S503 in FIG. 20). Subsequently, a control signal for generating a braking force identical to the target braking force X * new is output to the main braking device 26 and the sub - braking device 27 of the braking device 3 (S504 in FIG. 20). As a result, the main braking device 26 and the sub - braking device 27 generate a braking force corresponding to the virtual braking force T * (=T * old + YT) and the virtual stroke S * (=S * old + YS) for the vehicle. Thereafter, by repeating the flows of S301 to S504 from the acquisition of the pedal braking force T and the pedal stroke S, the generation of the braking force corresponding to the above - mentioned pedal braking force T and pedal stroke S is repeatedly executed. As a result, the main braking device 26 and the sub - braking device 27 generate a gradually increasing braking force for the vehicle. That is, based on the corrected pedal braking force T and pedal stroke S (corrected detected values), the braking force of the vehicle is controlled. Thereafter, by repeating the above flow, the generation of the gradually increasing braking force is executed multiple times.

[0032] Also, assume that after an object has fallen onto the brake pedal 10 and the fallen object is immediately removed from the brake pedal 10. Then, as shown in FIG. 23, the pedal braking force T rapidly decreases, and it is determined that the current pedal braking force T is smaller than the previous pedal braking force Told (T - Told < 0) (No in S306 of FIG. 15). That is, it is determined that the pedal braking force T is trending downward. Subsequently, the braking force calculation unit 32 determines that the previous pedal braking force Told is greater than the previous virtual braking force T * old (T* Determine that it is old <Told) (S304 "Yes" in FIG. 15), and use the virtual pedaling force T * As the previous virtual pedaling force T * Add the pedaling force change amount limit value YT to old to obtain the value (T * old + YT), and set the minimum value (MIN(T * old + YT, T)) (S308 in FIG. 15). As a result, as shown in FIG. 23, the gentle increase of the virtual pedaling force T * continues, and the difference between the virtual pedaling force T * and the pedal pedaling force T gradually decreases. The reduction of the difference between the above virtual pedaling force T * and the pedal pedaling force T is repeated. When the previous virtual pedaling force T * old and the previous pedal pedaling force Told become equal (T * old = Told; S304 "No" in FIG. 15), set the current pedal pedaling force T as the virtual pedaling force T * (S305 in FIG. 15). Similarly, the processes of S401 to S403, S406, S404, and S405 in FIG. 18 are executed, and the current pedal stroke S is set as the virtual stroke S * . Then, the braking force calculation unit 32 calculates the target braking force X * new based on the set virtual pedaling force T * and the virtual stroke S * (S501 to S503 in FIG. 20). Subsequently, a control signal for generating a braking force identical to the target braking force X * new is output to the main braking device 26 and the sub-braking device 27 of the braking device 3 (S504 in FIG. 20). As a result, the main braking device 26 and the sub-braking device 27 generate a braking force corresponding to the pedal pedaling force T and the stroke S, that is, a braking force that immediately decreases, in the vehicle. That is, when the pedal pedaling force T and the stroke S (detected values) are in a decreasing trend, the braking force of the vehicle is controlled based on the uncorrected pedal pedaling force T and the stroke S. Thereafter, by repeating the above process, the generation of the above-mentioned braking force that immediately decreases is executed multiple times.

[0033] (Effect of the Second Embodiment) (1) Here, as a comparative example, target braking force X * new Virtual pedaling force T for calculation * and virtual stroke S * Let's consider the case where pedal force T and stroke S are always used. In this case, for example, suppose an object falls onto the brake pedal 10, and a large load is instantaneously applied to the brake pedal 10 by the falling object, causing the pedal force T and stroke S to increase rapidly as shown in Figure 24. Then, the virtual pedal force T * and virtual stroke S * It also increased rapidly, target braking force X * The new force also increases rapidly, potentially causing the vehicle to brake suddenly. Figure 24 shows the target braking force X when an object falls onto the brake pedal 10 in a comparative example. * This is a diagram showing new, etc. In contrast, in the second embodiment, if the amount of change per predetermined time of pedal force T and stroke S (detected value) exceeds a threshold (pedance change limit value YT, stroke change limit value YS), the pedal force T and stroke S (detected value) are corrected in a direction that reduces the amount of change per predetermined time, and the braking force of the vehicle is controlled based on the corrected pedal force T and stroke S (corrected detected value). That is, the system is configured to include a limiter for the upper limit of the rate of change of pedal force T and stroke S. As a result, for example, if an object falls onto the brake pedal 10 and a large load is instantaneously applied to the brake pedal 10 by the falling object, and the pedal force T and stroke S increase rapidly as shown in Figure 23, the generation of a sudden braking force due to the sudden increase in pedal force T and stroke S can be suppressed. [Explanation of Symbols]

[0034] 1... Brake force control device, 8... Brake controller, 19... Pedal input detection unit

Claims

1. Based on the amount of change in the pedal posture of the vehicle's brake pedal or the detected value of the pedal force applied to the brake pedal, the braking force of the vehicle is controlled. If the amount of change per predetermined time of the detected value or a specific parameter calculated based on the detected value exceeds a threshold, the detected value or the specific parameter is corrected in a direction that reduces the amount of change per predetermined time, and the braking force is controlled based on the corrected detected value or the specific parameter. Braking force control method.

2. The threshold value increases as the elapsed time since the start of pressing the brake pedal increases. The braking force control method according to claim 1.

3. The threshold is increased as the detected value increases. The braking force control method according to claim 1.

4. When the detected value is on a downward trend, the braking force of the vehicle is controlled based on the detected value without correction or the specific parameter without correction. The braking force control method according to claim 1.

5. Based on the detected value, the provisional target braking force of the vehicle is calculated as the specific parameter, the target braking force of the vehicle is set based on the calculated provisional target braking force, and the braking force of the vehicle is controlled based on the set target braking force. If the amount of change in the provisional target braking force per predetermined time exceeds the threshold, the provisional target braking force is corrected in a direction that reduces the amount of change per predetermined time, and the corrected provisional target braking force is set as the target braking force. The braking force control method according to claim 1.

6. A detection unit that detects the amount of change in the pedal posture of the vehicle's brake pedal or the pedal force applied to the brake pedal and generates a detection value, The system includes a control unit that controls the vehicle based on the detected value generated by the detection unit, If the amount of change per predetermined time of the detected value or a specific parameter calculated based on the detected value exceeds a threshold, the control unit corrects the detected value or the specific parameter in a direction that reduces the amount of change per predetermined time, and controls the braking force of the vehicle based on the corrected detected value or the specific parameter. Brake force control device.

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