JP2006281870A - Brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the operability of a brake operation element at extremely low speed traveling such as at retreating and traffic jam of a vehicle. <P>SOLUTION: An electronic control unit 19 for controlling operation of a brake actuator 18 and a reaction force giving motor 12 based on a braking signal outputted by an encoder 13 increases a ratio of the reaction force relative to a stroke of the brake pedal at retreating or traffic jam of the vehicle and increases a ratio of braking force relative to the stroke of the brake pedal 11. Therefore, at retreating when operation burden of a driver is increased because the brake pedal 11 is hardly operated and at the traffic jam when operation burden of the driver is increased because operation frequency of the brake pedal 11 is high, the operation burden of the driver can be reduced by generating required braking force only by operating the brake pedal 11 by a small stroke. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a so-called brake-by-wire type brake device that generates a braking force by operating a brake actuator in response to a braking signal output in response to an operation of a brake operator by a driver.

A master cylinder that operates by operating the brake pedal of the driver to generate brake fluid pressure, and a hydraulic pump that operates by an electric motor to generate brake fluid pressure. When the hydraulic pump operates normally, the master cylinder In a brake-by-wire brake device that closes the solenoid valve located between the cylinder and the wheel brake and operates the wheel brake with the brake hydraulic pressure generated by the hydraulic pump in response to the depression force of the brake pedal, Patent Document 1 below discloses that the stroke of the brake pedal with respect to the same pedaling force is changed by the action of a stroke simulator by switching the electromagnetic valve from open to closed while the pedaling force increases. According to this brake device, the driver can easily increase the stroke of the brake pedal to generate the same braking force when driving the brake pedal by twisting the body backward when the vehicle is moving backward, compared to when the vehicle is moving forward. It is said that the braking force can be adjusted.
Japanese Patent Laid-Open No. 11-157439

  However, when a vehicle equipped with a normal automatic transmission reverses into the garage, a large braking force is not required, and by applying a slight braking force intermittently while moving the vehicle backward with a creep force, The vehicle is slowly moving backward to the target position. That is, when the vehicle moves backward, the magnitude of the braking force is not adjusted by the stroke of the brake pedal, but is adjusted by the time that the brake pedal is stepped on intermittently. Therefore, even if the stroke of the brake pedal is increased during reverse travel, it is difficult to reduce the burden on the driver when operating the brake pedal.

  In addition, since the driver twists his / her body backward when the vehicle is moving backward, it is difficult for the driver to reach the brake pedal. Therefore, when the stroke of the brake pedal becomes longer, the operation burden on the driver further increases.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to improve the operability of the brake operator when traveling at an extremely low speed such as when the vehicle is moving backward or when there is traffic.

  To achieve the above object, according to the first aspect of the present invention, a brake operator operated by a driver, a braking signal output means for outputting a braking signal corresponding to the operation of the brake operator, wheels A brake actuator that generates a braking force for braking, a reaction force applying means for applying a reaction force to the operation of the brake operator, and an operation of the brake actuator and the reaction force applying means based on a braking signal output by the braking signal output means The control means increases the ratio of the reaction force with respect to the stroke of the brake operator and the ratio of the braking force with respect to the stroke of the brake operator when the vehicle is moving backward or in a traffic jam. A brake device characterized by this is proposed.

  According to the second aspect of the present invention, the brake operator operated by the driver, the braking signal output means for outputting a braking signal corresponding to the operation of the brake operator, and the braking force for braking the wheel are generated. The brake actuator, a reaction force applying means for applying a reaction force to the operation of the brake operator, and a control means for controlling the operation of the brake actuator based on a braking signal output from the braking signal output means, the control means Proposes a braking device that reduces the amount of rising of the braking force at the initial stage of braking when the vehicle is moving backward or in a traffic jam.

  The brake pedal 11 of the embodiment corresponds to the brake operator of the present invention, the reaction force applying motor 12 of the embodiment corresponds to the reaction force applying means of the present invention, and the encoder 13 of the embodiment is a braking signal of the present invention. Corresponding to the output means, the electronic control unit 19 of the embodiment corresponds to the control means of the present invention.

  According to the configuration of claim 1, when the braking signal output means outputs a braking signal in accordance with the operation of the brake operator operated by the driver, the braking actuator is activated to generate a braking force for braking the wheel, The reaction force applying means applies a reaction force to the operation of the brake operator. The control means for controlling the operation of the brake actuator and the reaction force applying means based on the braking signal increases the ratio of the reaction force to the stroke of the brake operator when the vehicle is moving backward or in a traffic jam, and Since the ratio of braking force is increased, the brakes are difficult to operate and the brakes are difficult to operate. By operating the operating element with a small stroke, the necessary braking force can be generated to reduce the driver's operating burden.

  According to the second aspect of the present invention, when the braking signal output means outputs a braking signal in accordance with the operation of the brake operating element operated by the driver, the braking force that activates the brake actuator and brakes the wheel is obtained. The reaction force applying means applies a reaction force to the operation of the brake operator. The control means for controlling the operation of the brake actuator based on the braking signal reduces the amount of rising of the braking force at the initial stage of braking when the vehicle is moving backward or when there is a traffic jam. When the vehicle travels backward, or when the driver's operating load increases due to the high frequency of operation of the brake operator, the brake operator can be operated roughly to reduce the driver's operating load. Smooth braking can be performed by preventing the power from rising suddenly and causing discomfort to the occupant.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 8 show an embodiment of the present invention, FIG. 1 is a diagram showing an overall configuration of a brake-by-wire brake device, and FIG. 2 is a block diagram showing a circuit configuration of an electronic control unit, 3 is a flowchart of the reverse determination routine, FIG. 4 is a time chart for explaining the operation of the reverse determination, FIG. 5 is a flowchart of the traffic congestion determination routine, FIG. 6 is a time chart for explaining the operation of the traffic congestion determination, and FIG. FIG. 8 is a map for searching for braking force from the stroke or pedaling force of the brake pedal.

  As shown in FIG. 1, the brake-by-wire brake device includes a brake pedal 11 as a brake operator operated by a driver's foot, and pivotally supports the upper end of the brake pedal 11 so as to be swingable. A reaction force applying motor 12 as a reaction force applying means and an encoder 13 as a braking signal output means are connected to the supporting shaft. The brake pedal 11 is applied with a reaction force according to the stroke amount by the reaction force spring 14, and the brake pedal 11 has an arbitrary magnitude according to the stroke amount, the stroke speed, or other signals by the torque generated by the reaction force application motor 12. Reaction force is applied. The reaction force applying motor 12 not only generates a reaction force with respect to the operation of the brake pedal 11, but also has a function of changing an initial position of the brake pedal 11 (a position when no pedal force is applied). The encoder 13 outputs a signal corresponding to the operation amount of the brake pedal 11 (that is, the stroke of the brake pedal 11). The brake switch 15 detects the operation of the brake pedal 11 by the driver.

  On the other hand, the brake actuator 18 connected to the wheel cylinder 17 provided on the front and rear wheels 16 (only one wheel is shown in FIG. 1) of the vehicle is generated by a hydraulic pump or a hydraulic cylinder driven by a motor. The brake fluid pressure is controlled to an arbitrary magnitude and supplied to the wheel cylinder 17 to brake the wheel 16. The master cylinder is connected to the brake pedal 11, and the wheel cylinder 17 is operated with the brake fluid pressure generated by the master cylinder when the brake actuator 18 becomes inoperable due to a power failure or a control device failure. A fail-safe mechanism can be provided.

  In addition to the encoder 13 and the brake switch 15, the electronic control unit 19 that controls the operation of the reaction force applying motor 12 and the brake actuator 18 includes a vehicle speed sensor 20, a yaw rate sensor 21, a shift position sensor 22, a navigation device 23, and a VICS reception. A device 24 is connected.

  As shown in FIG. 2, the electronic control unit 19 includes pedal stroke calculation means M1, pedal speed calculation means M2, passive reaction force estimation means M3, rigidity reaction force calculation means M4, and viscous friction reaction force calculation means M5. The active reaction force compensation current calculation means M6 and the current control means M7 are provided. Signals from the encoder 13 are input to the pedal stroke calculation means M1 and the pedal speed calculation means M2, and a reaction force is applied to the current control means M7. The actual motor 12 current is fed back.

  Next, the operation of the embodiment having the above configuration will be described.

  In FIG. 2, when the driver operates the brake pedal 11, signals from the encoder 13 are input to the pedal stroke calculating means M1 and the pedal speed calculating means M2, and the pedal stroke calculating means M1 calculates the stroke of the brake pedal 11 and the pedal. The speed calculation means M2 calculates the stroke speed of the brake pedal 11. The passive reaction force estimation means M3 estimates the passive reaction force, that is, the reaction force generated by the reaction force spring 14 based on the stroke of the brake pedal 11.

  The active reaction force is a reaction force generated by the reaction force applying motor 12, which includes a rigid reaction force that simulates a reaction force that depends on the pedal position (stroke) when the brake pedal 11 is depressed, and the brake pedal 11. And a viscous friction reaction force that simulates a reaction force due to a viscous friction resistance that depends on the stepping speed (stroke speed) when stepping on the pedal, and the rigidity reaction force is based on the stroke of the brake pedal 11. The viscous friction reaction force is calculated by the calculation means M4, and the viscous friction reaction force calculation means M5 is calculated based on the stroke speed of the brake pedal 11.

  The active reaction force compensation current calculation means M6 subtracts the passive reaction force estimated by the passive reaction force estimation means M3 from the added value of the stiffness reaction force and the viscous friction reaction force, and the active reaction force to be generated in the reaction force applying motor 12 And the active reaction force is converted into a compensation current to be supplied to the reaction force applying motor 12. The current control means M7 performs feedback control so that the actual current flowing through the reaction force applying motor 12 matches the compensation current.

  When the vehicle is moving backward or in a traffic jam, the stiffness reaction force calculated by the stiffness reaction force calculation means M4 is corrected as follows.

  First, the reverse detection of the vehicle will be described.

  In the flowchart of FIG. 3, first, when the reverse control flag = 1 (that is, reverse) is not set in step S1, the vehicle speed (absolute value) is detected by the vehicle speed sensor 20 in step S2. If the vehicle speed is less than the threshold value in step S3, the brake switch 15 is ON in step S4, and the shift position detected by the shift position sensor 22 in step S5 is reverse, the reverse control flag is set to 1 in step S6. If the shift position is not reverse, the reverse control flag is reset to = 0 (ie, forward or stop) in step S7. If the reverse control flag = 1 in step S1, the process skips to step S5. If the shift position is reverse, the reverse control flag is set to 1 in step S6. If the shift position is not reverse, step S7 is executed. To reset the reverse control gragg to = 0.

  This operation will be specifically described based on the time chart of FIG. 4. From the state where the vehicle speed is less than the threshold value at time t1 and the brake switch 15 is ON, the shift position is shifted backward at time t2. Then, the reverse control flag = 1 is set. Once the reverse control flag = 1 is set in this way, the reverse control flag = 0 is not reset even if the vehicle speed exceeds the threshold value or the brake switch 15 is turned off, and the shift is made at time t3. When the position is changed to a position other than reverse, the reverse control flag = 0 is reset.

  Next, detection of traffic congestion will be described.

  In the flowchart of FIG. 5, first, GPS information is received by the navigation device 23 in step S11 and VICS information is received by the VICS receiving device 24, and the vehicle speed and yaw rate are detected by the vehicle speed sensor 20 and the yaw rate sensor 21 in step S12. In S13 and S14, the navigation device 23 searches the map information to identify the vehicle position.

  If it is determined in step S15 from the VICS information that the vehicle is not currently at the traffic jam prediction point, the traffic jam control flag is reset to 0 in step S23, and the brake counter is initialized in step S24. If it is determined in step S15 that the host vehicle is currently at a traffic congestion prediction point, the vehicle speed is compared with a threshold value in step S16. In step S22, if the timer value is not less than 3 seconds, that is, if the timer value is 3 seconds or more, the process proceeds to steps S23 and S24 to reset the congestion control flag = 0 and initialize the brake counter. Turn into.

  On the other hand, if the vehicle speed is less than the threshold value in step S16 or if the answer to step S22 is YES and the vehicle speed is greater than or equal to the threshold value for less than 3 seconds, the process proceeds to step S17. When the brake switch 15 is switched ON / OFF at step S17, the brake counter is incremented at step S18. When the count value of the brake counter becomes three times or more at step S19, the congestion control flag is set to 1 at step S20. To do.

  This action will be specifically described based on the time chart of FIG. 6. When the vehicle speed is determined to be less than the threshold at time t2 when it is determined that the traffic congestion is predicted at time t1, the brake switch 15 is switched from ON to OFF at time t3. When the brake switch 15 is switched from OFF to ON at time t4, and when the brake switch 15 is switched from ON to OFF at time t5, the count value of the brake counter reaches 3 and the congestion control flag = 1. Set. If the vehicle speed becomes equal to or greater than the threshold at time t6 and the timer counts 3 seconds and there is no ON / OFF switching of the brake switch 15, the congestion control flag is reset to 0 at time t7. .

  When the reverse or congestion of the vehicle is determined as described above, the rigidity reaction force calculation means M4 (see FIG. 2) changes the table used when calculating the rigidity reaction force from the stroke of the brake pedal 11, As shown in FIG. 7, the rigidity reaction force indicated by a solid line is changed to a characteristic indicated by a broken line during reverse traveling or traffic jam during normal times. Specifically, with respect to the same stroke of the brake pedal 11, the rigidity reaction force is changed so that the rigidity reaction force at the time of reverse traveling or traffic jam is higher than that at the normal time. Incidentally, the chain line is a characteristic of what is described in Patent Document 1, and contrary to the present embodiment, it is changed so that the rigidity reaction force at the time of reverse travel is lower than that at the normal time.

  Further, as shown in FIG. 8A, the magnitude of the braking force with respect to the stroke of the brake pedal 11 is changed by changing the map used when calculating the braking force generated by the brake actuator 18 from the stroke of the brake pedal 11. , It is changed so that it is higher during reverse or in traffic than in normal times. Further, as shown in FIG. 8B, by changing the map used when calculating the braking force generated by the brake actuator 18 from the depression force (reaction force) of the brake pedal 11, the depression force (reaction force) of the brake pedal 11 is changed. The jumping amount is changed so that it is lower when traveling backwards or when there is traffic.

  By the way, since the vehicle speed is extremely low when the vehicle goes backward for entering a garage or when there is a traffic jam, the driver often turns the brake pedal 11 on / off and moves the vehicle with a creep force. During reverse travel, the driver twists his / her body backward, making it difficult for the driver to reach the brake pedal 11, and if the stroke of the brake pedal 11 is large, the operation becomes difficult. Further, since it is necessary to frequently operate the brake pedal 11 in a traffic jam, there is a possibility that the driver will be fatigued if the stroke of the brake pedal 11 is large.

  However, in this embodiment, the reaction force when the brake pedal 11 is stroked by the same amount during reverse travel or traffic congestion increases, so the stroke required to generate the same braking force is reduced and the driver's operation burden is reduced. Can be reduced.

  Further, in general, in the brake device, when a depression force of the brake pedal 11 reaches a predetermined value, the braking force is increased to a jumping amount at once, so that a so-called jumping function is provided so as to enhance a feeling of response (biting feeling) at the initial stage of braking. It has become.

  However, when creeping with the brake pedal 11 frequently turned on and off, such as during reverse travel or traffic jams, if the braking force rises suddenly when the brake pedal 11 is depressed, an unpleasant sudden There is a risk that the vehicle will be in a braking state and feel uncomfortable.

  Therefore, in this embodiment, by setting the jumping amount at the time of reverse travel and traffic jam to be smaller than the jumping at the time of normal operation, the brake pedal 11 is difficult to operate and the reverse operation when the driver's operation load increases, In order to reduce the driver's operation load by making it possible to roughly operate the brake pedal 11 in a traffic jam where the driver's operation load increases because the frequency of operating the vehicle 11 increases, the braking force does not rise suddenly. Thus, the movement of the vehicle can be prevented from becoming jerky.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the brake pedal 11 is illustrated as the brake operator, but the brake operator may be a brake lever.

Diagram showing the overall configuration of a brake-by-wire brake device Block diagram showing circuit configuration of electronic control unit Reverse determination routine flowchart Time chart explaining the action of reverse determination Flow chart of traffic jam judgment routine Time chart explaining the effect of traffic jam detection Table to search brake pedal stroke or brake pedal stiffness reaction force A map that searches for braking force from the stroke or pedaling force of the brake pedal

Explanation of symbols

11 Brake pedal (brake operator)
12 reaction force motor (reaction force applying means)
13 Encoder (braking signal output means)
16 Wheel 18 Brake actuator 19 Electronic control unit (control means)

Claims (2)

A brake operator (11) operated by a driver;
Braking signal output means (13) for outputting a braking signal according to the operation of the brake operator (11);
A brake actuator (18) for generating a braking force for braking the wheel (16);
Reaction force applying means (12) for applying a reaction force to the operation of the brake operator (11);
Control means (19) for controlling the operation of the brake actuator (18) and the reaction force applying means (12) based on the braking signal output by the braking signal output means (13),
The control means (19) increases the ratio of the reaction force to the stroke of the brake operator (11) and increases the ratio of the braking force to the stroke of the brake operator (11) when the vehicle is moving backward or in a traffic jam. Brake device characterized by that. A brake operator (11) operated by a driver;
Braking signal output means (13) for outputting a braking signal according to the operation of the brake operator (11);
A brake actuator (18) for generating a braking force for braking the wheel (16);
Reaction force applying means (12) for applying a reaction force to the operation of the brake operator (11);
Control means (19) for controlling the operation of the brake actuator (18) based on the braking signal output by the braking signal output means (13),
The control means (19) reduces the rising amount of the braking force at the initial stage of braking when the vehicle is moving backward or when there is traffic.

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