JP4206889B2 - Brake reaction force characteristic control device - Google Patents

Description

  The present invention relates to a brake device including a stroke simulator, for example, which is connected to a brake operator that is stroked by a driver's operation and applies a brake reaction force corresponding to the stroke to the brake operator. The present invention relates to a technique for controlling a brake reaction force / stroke characteristic, which is a reaction force characteristic with respect to a stroke of an operator.

As a stroke simulator that is used in this type of brake device and has a variable relationship between the brake operation amount of the brake operator operated by the driver and the brake reaction force accompanying the brake operation, for example, disclosed in Patent Document 1 Things are known.
JP 2000-135976 A

  The brake stroke simulator device described in Patent Document 1 is a relationship between a driver's brake operation amount (hereinafter referred to as a stroke) and a brake pedal reaction force, that is, a brake reaction force, according to the driver's preference and the driving situation of the vehicle.・ Stroke characteristics are variable.

However, the conventional brake stroke simulator device has the following problems.
That is, Patent Document 1 does not specifically disclose how the reaction force characteristic is changed based on the driver's preference or the driving situation of the vehicle. For this reason, conventionally, it has not been possible to specifically use the brake device with variable brake reaction force / stroke characteristics of the brake pedal for the purpose of improving driving performance or safety.

  In addition, the brake stroke simulator device described in Patent Document 1 has a problem that the initial pedaling force at the start of depression of the brake pedal cannot be changed, and a problem that the maximum sliding amount of the piston fluctuates when the reaction force characteristic is changed. Therefore, it is not preferable for the driver to operate the brake.

  The present invention makes it possible to control the brake reaction force / stroke characteristics including the initial reaction force of the brake pedal, and to control the brake reaction force / stroke characteristics without causing fluctuations in the maximum sliding amount. The present invention intends to propose a reaction force characteristic control device for a brake device.

For this purpose, the reaction force characteristic control device for a brake device according to the present invention comprises:
In a brake device comprising a brake operator stroked by a driver's operation, and a brake reaction force / stroke characteristic changing means capable of changing a reaction force characteristic with respect to the stroke of the brake operator,
It includes a running state detection means for detecting a steering reaction force of a steering system operated by a driver ,
Additional brake reaction-stroke characteristic changing means, which is constituted so as to change the brake reaction-stroke characteristic that the more brake reaction the steering reaction force is large is increased on the basis of the steering reaction force.

According to such a configuration of the present invention, the brake reaction force / stroke characteristic including the initial reaction force of the brake pedal is controlled because the brake reaction force / stroke characteristic is set based on the detected or estimated traveling state of the vehicle. It is possible to control the brake reaction force / stroke characteristic while keeping the maximum stroke amount of the brake operator unchanged.
Therefore, it is possible to adjust the brake pedal depressing force with a higher degree of freedom than a brake device equipped with a conventional variable stroke simulator, and the brake device's brake response can be adapted to a wide range of situations such as the driver's preference and the driving environment of the vehicle. The force / stroke characteristics can be adjusted.
And since the brake reaction force / stroke characteristics are set based on the detected or estimated driving state of the vehicle, the driver always adjusts the brake reaction force / stroke characteristics optimally without adjusting the brake reaction force / stroke characteristics. Driving with the characteristics becomes possible, and the drivability and safety of the vehicle can be improved.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 is a system diagram showing an operation unit of a brake-by-wire brake device including a reaction force characteristic control device according to an embodiment of the present invention.

Reference numeral 1 denotes a brake pedal that the driver depresses when braking the vehicle. The brake pedal 1 is connected to a push rod 2 a of the master cylinder 2.
When the master cylinder 2 is pushed into the push rod 2a during braking operation, when the piston cups 2b and 2c pass through the communication ports 2e and 2f with the reservoir tank 2d, the master cylinder hydraulic pressure is applied to the cylinder chambers 2g and 2h. It is generated and directed to the brake hydraulic system 3 and 4.

However, while the brake-by-wire system is normal, the on-off valves 5 and 6 inserted in the brake hydraulic systems 3 and 4 are closed, and the wheel cylinders (see FIG. The brake fluid pressure to be directed to the vehicle is controlled according to the master cylinder fluid pressure, and the brake device operates as a so-called brake-by-wire system.
When the brake-by-wire system breaks down, the on-off valves 5 and 6 are opened, and the master cylinder hydraulic pressure is supplied as it is downstream of the on-off valves 5 and 6 to the wheel cylinder (not shown) to avoid inability to brake. A fail-safe function can be fulfilled.
In the present embodiment, the master cylinder 2 is shown as having two brake hydraulic systems 3 and 4, but only one system 3 may be used.

  A switching valve 7 is provided in the brake hydraulic pressure line portion between the opening / closing valve 5 related to the brake hydraulic system 3 and the master cylinder 2, and this switching valve 7 is provided in the master cylinder chamber 2g while the brake-by-wire system is normal. Is communicated with the stroke simulator 8 so that a brake reaction force can be applied to the brake pedal 1 by the stroke simulator 8, and when the brake-by-wire system fails, the master cylinder chamber 2g is communicated with the brake hydraulic system 3. The fail-safe function can be achieved.

Next, the stroke simulator 8 will be described in detail.
The stroke simulator 8 is intended to apply the brake reaction force to the brake pedal 1 as described above, but the reaction force characteristic with respect to the pedal stroke (hereinafter referred to as the brake reaction force / stroke characteristic) can be changed. The configuration is as follows.
A port 12 that communicates with the switching valve 7 is provided at one end of the cylinder 11 that forms the outline of the stroke simulator 8.
A space surrounded by one end of the cylinder 11 on the port 12 side, the inner wall of the cylinder 11, and the piston 13 that strokes in the cylinder 11 forms a liquid chamber 10 filled with the working fluid. The liquid chamber 10 exchanges hydraulic fluid with the liquid chamber 2 g in the master cylinder 2.
A receiving seat 14 is provided between the opposite surface of the piston 13 when viewed from the liquid chamber 10 and the other end of the cylinder 11. An elastic body 15 such as a spring is contracted between the piston 13 and the receiving seat 14. Further, an elastic protrusion 16 such as rubber is projected from the receiving seat 14 toward the piston 13 in parallel with the spring 15.

In a non-braking state where the brake pedal 1 is not depressed, the piston 13 is at one end on the port 12 side in the cylinder 11 and is urged toward the port 12 by the initial load of the spring 15. The tip of the elastic protrusion 16 is away from the piston 13, and the spring constant of the elastic protrusion 16 is larger than the spring constant of the spring 15.
The receiving seat 14 is supported by a stopper 17 provided at the other end of the cylinder 11 via a rod 18, and by an initial load of an elastic body 19 such as a spring contracted between the receiving seat 14 and the other end of the cylinder 11. It is biased toward the port 12 side. The spring constant of the spring 19 is made larger than the spring constant of the spring 15. The other end of the cylinder 11 and the stopper 17 are provided with a hole 20 for venting air so that the stroke of the piston 13 is not obstructed.

  The rod 18 slidably penetrates a guide 21 provided at the other end of the cylinder 11, and the receiving seat 14 can stroke in the cylinder 11 integrally with the rod 18. The hollow cylindrical stopper 17 with one end opening has a female thread groove on the inner periphery. On the other hand, a male screw groove is formed on the outer periphery of the other end portion of the cylinder 11, and one end openings of the stopper 17 are screwed to each other. By rotating the stopper 17, the screwing position is variable, and the relative position with respect to the cylinder 11 can be adjusted by sliding.

The other end of the stopper 17 far from the port 12 is closed, and a through-hole 22 through which the rod 18 passes is formed at the center of the other end. The inner diameter of the through hole 22 is larger than the outer diameter of the rod 18, and the rod 18 can move relative to the stopper 17. Further, since the through hole 22 is smaller than the head 23 provided at the other end of the rod 18 on the opposite side as viewed from the receiving seat 14, the head 23 is not connected to the stopper 17 in a non-braking state where the brake pedal 1 is not depressed. It is locked and cannot access the port 12 more than that position.
Therefore, the stopper 17 defines the position in the non-braking state of the receiving seat 14 provided at the tip of the rod 18 closer to the port 12 (distance S between the receiving seat 14 and the other end of the cylinder 11). This position can be adjusted by adjusting the screwing position of the stopper 17.
On the other hand, the receiving seat 14 can make a stroke in the direction of the stopper 17 from the non-braking position S in FIG. Even if the position of the air vent hole 20 on the cylinder 11 side and the position of the air vent hole 20 on the stopper 17 side are shifted from each other with the other end of the stopper 17 being in close contact with the other end of the cylinder 11, the air vent hole 20. An annular groove 20a is provided on the inner wall of the other end of the stopper 17 so that the stopper 17 is not blocked.

Gear teeth 24 are formed on the outer periphery of the stopper 17, and a pinion 25 is engaged therewith. The pinion 25 is coupled to the output shaft 26 of the motor 27, and the motor 27 is fixed to a vehicle body side member (not shown).
When the distance S from the other end of the cylinder 11 to the non-braking position of the receiving seat 14 is adjusted, the reaction force characteristic control unit 28 is driven by the screw action generated when the motor 27 is driven to rotate the stopper 17. Make adjustments.

  When the driver starts to depress the brake pedal 1 from the non-braking state, the working fluid in the master cylinder fluid chamber 2g flows into the fluid chamber 10 through the switching valve 7, and acts on the piston 13 toward the other end of the cylinder 11. give. On the other hand, the initial load of the spring 15 acts on the piston 13 in the direction of the port 12, and when the acting force is larger than the initial load, the piston 13 starts a stroke in the other end direction of the cylinder 11 to The volume is increased, the volume of the separation chamber 5 is decreased, and the brake pedal 1 starts a stroke. That is, if the distance S is set large, the initial load of the spring 15 increases and the initial pedal reaction force for starting the stroke also increases. This brake (pedal) reaction force / stroke characteristic is shown in FIG.

In the initial step of the depression of the brake pedal 1, the piston 13 strokes in the direction of the stopper 17 while mainly contracting the spring 15 having a small constant. Therefore, the change in the pedal reaction force (the depression force) with respect to the stroke of the brake pedal 1 is shown in FIG. As shown, it is moderate.
Further, the brake (pedal) reaction force at the start of the stroke increases as the distance S is set larger.

  Then, in the final step of the depression after the piston 13 strokes to the vicinity of the seat 14 and the spring 15 having a small spring constant reaches the maximum contraction, the contraction of the spring 15 stops and only the spring 19 contracts, so that the liquid chamber 10 absorbs the hydraulic fluid discharged from the liquid chamber 2g. In other words, as shown in FIG. 3, the brake (pedal) reaction force / stroke characteristic can be realized as a two-stage characteristic that changes at the break points c and c ′.

  Then, when the hydraulic pressure in the liquid chamber 10 increases and the contraction of the spring 15 and the spring 19 reaches the maximum, the process proceeds to the final stepping step, and the tip of the elastic protrusion 16 receives the pressing force from the piston 13. Deforms by pressing. That is, as shown in FIG. 4, the stroke amount with respect to the pedal reaction force becomes smaller by passing through the break points d and d ′. As a result, the ideal characteristic of the stroke simulator 8 becomes harder in proportion to the distance S as shown by the broken line, and the reaction force / stroke characteristic of the brake pedal 1 is from the other end of the cylinder 11 to the non-braking position of the receiving seat 14. When the distance S is increased, the reaction force is set to be larger (harder), and when the distance S is set to be smaller, the reaction force is set to be smaller (softer).

  Since the initial pedal reaction force at which the driver starts depressing the brake pedal 1 from the non-braking state and the brake pedal 1 starts a stroke is proportional to the distance S as described above, as shown in FIG. When the distance S is set to the maximum with the screwing position of the cylinder close to the cylinder 11, the initial load of the spring 15 increases and the initial pedal reaction force for starting the stroke also increases. That is, the pedal reaction force / stroke characteristics are variable.

  In the final step, the hydraulic pressure of the hydraulic fluid in the liquid chamber 10 is received and the piston 13 strokes toward the other end of the cylinder 11 as shown in FIG. The distal end portion of 16 receives the pressing force from the piston 13 and is deformed by pressing.

  On the other hand, when the screwing position of the stopper 17 is set far from the cylinder 11 and the distance S is set small as shown in FIG. 7, the initial load of the spring 15 is reduced and the initial pedal reaction force for starting the stroke is also reduced.

  Then, in the final step, the hydraulic pressure of the hydraulic fluid in the liquid chamber 10 is received and the piston 13 strokes to the other end side of the cylinder 32 as shown in FIG. The distal end portion of 16 receives a pressing force from the piston 34 and is deformed by pressing.

  Since the receiving seat 14 can stroke in the direction of the stopper 17, even if the distance S from the other end of the cylinder 11 to the non-braking position of the receiving seat 14 is adjusted and the setting of the initial pedal reaction force is adjusted, FIG. As shown in FIG. 8, the maximum stroke amount of the piston 13 is unchanged. That is, since the maximum volume of the liquid chamber 10 is the volume of the cylinder 11 and does not change, even if the setting of the initial pedal reaction force is adjusted, the maximum stroke amount of the brake pedal 1 does not change.

Next, the control of the pedal reaction force characteristic of the brake pedal 1 including the stroke simulator 8 having the initial pedal reaction force and the brake reaction force / stroke characteristic variable described above will be described.
This control is executed by the reaction force characteristic control unit 28 in FIG. 1 adjusting the screwing position of the stopper 17 via the motor 27. Basically, the driver operates the pedal reaction force select switch 29. Auto mode A for automatic control, Hard H for setting reaction force characteristics always large, Soft S for setting reaction force characteristics always small, Medium M mode for setting reaction force characteristics always in the intermediate range It is assumed that the reaction force characteristic command of the brake pedal 1 having selected is realized.
Therefore, a select signal corresponding to the mode selected by the pedal reaction force select switch 29 is output to the reaction force characteristic control unit 28.

  Further, a signal relating to the vehicle speed V detected by the vehicle speed sensor 30 is input to the control unit 28. In addition, as a signal related to the vehicle speed V, a vehicle speed V calculated using each wheel speed detected by the anti-skid control device (ABS), a vehicle speed V calculated from the rotation speed of the transmission output shaft, or the like may be used. Good.

In addition to the control unit 28, a snow mode ON / OFF signal from a snow mode switch 31 that is operated by a driver to select a snow mode of an automatic transmission for driving on a snowy road,
A steering reaction force signal from the power steering controller 32 representing a steering reaction force detected by a steering shaft torque sensor of an electric power steering system that assists a steering force (steering reaction force) of a steering wheel (not shown);
A signal from the steering angle sensor 33 for detecting the steering angle θ of the steering wheel;
An anti-skid control ON / OFF signal from the ABS controller 35 for instructing anti-skid control for controlling the braking force of the wheel independently of the driver's braking operation in order to prevent the brake locking of the wheel;
A signal from a stroke sensor 36 that detects a stroke amount of the push rod 2a (stroke amount of the brake pedal 1) L;
In order to suppress the difference between the vehicle body yaw requested by the driver and the actual vehicle body yaw, the vehicle dynamics controller 37 controls the difference in braking force between the left and right wheels of the vehicle independently of the driver's braking operation. Vehicle dynamics control (VDC) ON / OFF signal,
A signal relating to the master cylinder hydraulic pressure Pm detected by a hydraulic pressure sensor 38 provided between the master cylinder 2 and the switching valve 7;
A signal relating to the engine braking force (vehicle deceleration not depending on the driver's braking operation) calculated by the engine braking force calculation unit 39 is input.

Here, when the driver turns on the snow mode switch 31 and selects the snow mode, an automatic transmission (not shown) is controlled so as to enable smooth start on a snowy road having a low friction coefficient μ on the road surface. It works to do.
The engine braking force calculation unit 39 calculates the engine braking force (vehicle deceleration not depending on the driver's braking operation) from the engine throttle opening (not shown), the vehicle speed V, and the overall transmission ratio of the vehicle transmission system. It can be estimated from the engine rotation deviation between the determined reference engine speed and the actual engine speed.

  Based on the input signal, the control unit 28 executes the control program shown in the flowchart in FIG. 9 at regular intervals to control the reaction force / stroke characteristics of the brake pedal 1.

First, in step S1, a select signal from the pedal reaction force select switch 29 is read.
In the next step S2, it is determined whether or not the selected mode of the pedal reaction force selection switch 29 is the auto mode.
If it is not the auto mode, the process proceeds to step S3, and it is determined whether the selection mode of the pedal reaction force select switch 29 is the manual mode of hardware H, medium M or software S.
In the next step S4, the target position (cylinder) of the stopper 17 corresponding to the selection mode (H, M, S) determined in step S3 is referred to with reference to the characteristic diagram illustrated in FIG. 10 stored in advance. 11 to calculate the target distance Sm) from the other end of 11 to the non-braking position of the seat 14. As shown in FIG. 10, when the selection mode is hard H, the target distance Sm is increased, and when the selection mode is soft S, the target distance Sm is decreased.
After calculating the target distance Sm, the process proceeds to step S27. In step S27, a drive command is output to the motor 27, the motor 27 is driven, the stopper 17 is adjusted to the target position calculated in step S4, and the process proceeds to return.

On the other hand, if it is determined in step S2 that the auto mode is set, the process proceeds to step S5, and the vehicle speed V is read from the vehicle speed sensor 30.
In the next step S6, with reference to the characteristic diagram illustrated in FIG. 11 stored in advance, the basic target position of the stopper 17 in the auto mode according to the vehicle speed V read in step S5 (other cylinder 11). The basic target distance Sa) from the end to the non-braking position of the receiving seat 14 is calculated.
As shown in FIG. 11, for example, the basic target distance Sa is set to 0 when the vehicle speed V, which is a low speed region such as an urban area where the brake operation frequency is high, is 30 km / h or less, and the basic target position is kept constant to prevent hunting. . In the middle / high speed range where the vehicle speed V exceeds 30 km / h, the basic target distance Sa increases in proportion to the vehicle speed V.

After obtaining the basic target position of the stopper 17 in step S6, the on / off signal of the snow mode switch 31 is read in step S7.
In step S8, a correction coefficient A corresponding to the ON or OFF signal read in step S7 is calculated with reference to a characteristic diagram illustrated in FIG.
Here, the correction coefficient A is set to 1.2, for example, when the snow mode is ON, and the correction coefficient A is set to 1, for example, when the snow mode is OFF.

In step S9, the steering reaction force signal from the power steering controller 32 is read.
In step S10, a correction coefficient B corresponding to the steering reaction force signal read in step S9 is calculated with reference to a characteristic diagram illustrated in FIG.
Here, the correction coefficient B is increased as the steering reaction force of the power steering increases, and the characteristic of the correction coefficient B experimentally obtained so that the driver feels that the balance between the steering reaction force and the brake pedal reaction force is good. Is set as shown in FIG. 13, for example. This characteristic may be not only linear as shown in FIG. 13 but also non-linear.

In step S11, the steering angle θ detected by the steering angle sensor 33 is read.
In step S12, with reference to a characteristic diagram as illustrated in FIG. 14 stored in advance, the lateral angle generated during turning is determined from the steering angle θ read in step S11 and the vehicle speed V read in step S5. A force (lateral acceleration G) is calculated, and a correction coefficient C corresponding to the lateral force is calculated.
The correction coefficient C is set to 1 when the lateral force is almost straight and the lateral force is small, for example, up to 0.01G, and the correction coefficient C is increased in proportion to the increase in the lateral force in the range of 0.01G to 1G.

In step S13, the pedal depression amount L output from the stroke sensor 36 is read, and the pedal depression velocity Vp is calculated from the amount of change in L during the calculation cycle.
In the next step S14, it is checked whether or not the pedal depression speed Vp exceeds a certain value Vs, and it is determined whether or not the driver is operating a sudden brake. If sudden braking is in progress, the process proceeds to step S15, and the correction coefficient D is set to 0.8, for example. On the other hand, if not suddenly braking, the process proceeds to step S16, and the engine brake force output from the engine brake force calculating unit 39 is read.

In the subsequent step S17, a correction coefficient D corresponding to the read engine braking force is calculated with reference to a characteristic diagram illustrated in FIG. If the engine braking force is in a very small range, the correction coefficient D is set to 1.0 and correction is not performed. The correction coefficient D is increased in proportion to the increase in the engine braking force. For example, 1.2.
For simplification of the system, the correction coefficient D may be calculated based on a selected shift stage of an automatic transmission (not shown) without providing the engine brake force calculation unit 39. In other words, the engine braking force increases as the gear position becomes lower, so the correction coefficient D may be increased as the gear shifts, for example.

In step S18, the hydraulic pressure Pm in the master cylinder 2 at the current time is read.
In step S19, it is determined whether or not the read hydraulic pressure Pm is greater than zero. When Pm = 0, it is determined that the vehicle is not braked, and the process proceeds to step S20. In step S20, the timer Tmr for measuring the brake operation duration time is reset to 0, and the process proceeds to step S23. On the other hand, if Pm> 0, it is determined that the brake is being operated, and in the next step S21, the timer Tmr for measuring the brake operation duration time is incremented (incremented) by the calculation cycle + Ts and the brake operation is started. Continue to measure the elapsed time (brake operation duration).

  In the next step S22, a correction coefficient E corresponding to the brake operation duration time Tmr measured in step S21 is calculated with reference to a characteristic diagram illustrated in FIG. Here, the correction coefficient E is set to 1 when the brake operation duration time Tmr is short. For example, when the calculation cycle Ts is 10 msec, E = 1 is set until Tmr = 200 (brake operation duration time is 2 sec). When the brake operation duration is longer than that, the correction coefficient E is made asymptotic to, for example, 0.8 as the duration increases.

  In step S23, the on / off signal from the ABS controller 35 and the on / off signal from the VDC controller 37 are read. In step S24, based on the read signal, it is determined whether or not anti-skid control is operating and whether or not vehicle dynamics control is operating. If any one or more are operating (Yes), in the next step S25, the current position of the stopper 17 (distance S from the other end of the cylinder 11 to the non-braking position of the receiving seat 14) is held, and a return is performed. Migrate to

On the other hand, if none is operating (No), the process proceeds to step S26, and correction coefficients A, B, C, D, E are added to the basic target position (basic target distance Sa) calculated in step S6 as shown in the following equation. To calculate the target position of the stopper 17 (target distance Sta from the other end of the cylinder 11 to the non-braking position of the receiving seat 14).
Sta = Sa × A × B × C × D × E (2)

  In step S27, a drive command is output to the motor 27, the motor 27 is driven, the stopper 17 is adjusted to the target position calculated in step S26, and the process proceeds to return.

By the way, according to the configuration of the present embodiment described above, the brake pedal 1 has variable initial reaction force and brake reaction force / stroke characteristics as shown in FIG. Thus, the reaction force characteristic can be obtained by adjusting the brake reaction force / stroke characteristic of the brake device in a wide range as compared with the conventional stroke simulator.
The control content of the reaction force characteristic of the brake pedal 1 is received from the end of the cylinder 11 far from the port 12 in proportion to the vehicle speed V as shown in step S6 on the flowchart shown in FIG. Since the basic target distance Sa to the non-braking position of the seat 14 is increased, as shown in FIGS. 17A and 17B, the brake reaction force of the brake pedal 1 increases as the vehicle speed V increases. Therefore, when driving on an expressway or on a circuit, the stroke change with respect to the pedaling force is reduced to create a sense of rigidity, while at low speeds such as when entering a garage or driving in urban areas, the brake reaction force is reduced. Makes it easier for the user to operate the brake. As a result, the driver can easily control the deceleration of the vehicle and can reduce fatigue.

In addition, when the friction coefficient μ of the traveling road surface is low, when the brake pedal 1 strokes with a small pedal force, the anti-skid control is activated only by lightly stepping on the driver, and the stepping amount (stroke amount) is slightly adjusted. It becomes difficult to operate the brake so that the anti-skid control is not activated. However, according to the above-described embodiment, it is estimated that the friction coefficient μ of the traveling road surface is lower than usual during the snow mode operation, and the correction coefficient A is increased from 1 to 1.2 in step S8. By increasing the reaction force characteristic of the pedal 1, it is possible to easily realize a breaking operation that does not activate the anti-skid control.
In addition to this embodiment, the relationship between the brake operation amount and the longitudinal acceleration obtained on the dry road surface is stored in the control unit in advance, and this relationship includes the actual brake operation amount and the detected longitudinal acceleration. The friction coefficient μ of the road surface may be estimated in small increments, and the reaction force characteristic of the brake pedal 1 may be increased in inverse proportion to the estimated road surface friction coefficient μ as shown in FIG.
Alternatively, the brake reaction force and stroke amount of the brake pedal 1 when the anti-skid control is activated are stored in memory, and thereafter the brake that activates the anti-skid control even if the same brake reaction force is input to the brake pedal 1. The basic target distance Sa may be adjusted so as to increase the brake reaction force / stroke characteristics so that it is difficult to reach the stroke.

Further, according to the present embodiment described above, the brake operation duration time Tmr is measured in step S21, and in step S22, the correction coefficient E is calculated to be smaller as the brake operation duration time Tmr is longer. And as shown in (b), the brake reaction force / stroke characteristic is changed so that the brake reaction force becomes smaller as the brake operation duration time becomes longer. Therefore, the longer the brake operation duration per time, the smaller the pedal effort of the brake pedal 1 and the easier it is to hold the stroke position of the brake pedal 1 to reduce driver fatigue and constant deceleration. Easy to keep.
In addition to the master cylinder hydraulic pressure Pm, the brake operation duration time may be calculated by using a means that can detect that the brake is being operated, such as a brake switch signal (not shown), the brake pedal stroke sensor 36, and the like.

  Also, according to the above-described embodiment, when the steering reaction force of the power steering is large in step S10 using the power steering device in which the reaction force / steering angle characteristic of the steering wheel is variable, the correction coefficient B is As shown in FIG. 20, as the power steering reaction force characteristic is increased, the brake reaction force / stroke characteristic is changed so that the depression force of the brake pedal 1 is increased. The braking force of the brake pedal can be increased to improve the high-speed stability, and the steering performance can be improved by reducing the pedaling force of the brake pedal while reducing the steering reaction force in city driving and low-speed driving. Thus, the steering steering reaction force characteristic and the brake pedal reaction force characteristic can be coordinately controlled, and the operation force balance of the entire operation system can be harmonized to improve the driving performance.

Further, according to the above-described embodiment, the correction coefficient C is increased as the lateral force (lateral acceleration G) is increased in step S12, so that the turning speed is fast or the turning radius is small as shown in FIG. As the lateral force increases, the reaction force / stroke characteristic of the brake pedal 1 increases. Accordingly, lateral acceleration is applied to the driver during turning, and the driver applies force to the whole body against this lateral force. As a result, the driver steps on the brake pedal 1 while stepping on the foot. Even in this case, it is possible to help maintain the operability of the brake pedal 1 and the posture of the driver.
In addition to the present embodiment, the yaw rate may be detected by providing a sensor, the lateral acceleration may be directly detected by providing a lateral force sensor, or the correction coefficient C may be calculated according to the steering angle θ.

  Further, according to the above-described embodiment, since the correction coefficient D is normally increased in proportion to the engine brake force in step S17, the vehicle deceleration (engine brake force) that does not depend on the operation of the brake pedal 1 is increased. When detected, the brake reaction force / stroke characteristic is changed so that the brake reaction force increases as the vehicle deceleration (engine brake force) increases as shown in FIG. Therefore, when the vehicle deceleration (engine braking force) not caused by the braking device is large, the braking force caused by the braking device can be reduced, and even when the engine braking force is large, the sum of the entire braking force can be reduced. Is prevented from becoming too large, and a stable deceleration feeling is easily realized.

  On the other hand, if it is determined in step S14 that the brake is suddenly applied, in the subsequent step S15, the driver can make a sudden change by changing the brake reaction force / stroke characteristics so that the correction coefficient D is made smaller than 1 and the brake reaction force is reduced. When the brake pedal 1 is quickly depressed in response to a brake, the pedal operation becomes lighter, so that braking can be quickly performed with less pedaling force, and the braking distance can be shortened. In addition to this embodiment, the correction coefficient may be gradually reduced so that the brake reaction force decreases as the engine braking force increases.

  Further, according to the above-described embodiment, if the vehicle turning control device such as the anti-skid control or the vehicle dynamics control is in operation, the position of the stopper 17 is not adjusted in step S25 and the position is maintained as it is. Therefore, the brake reaction force / stroke characteristic of the brake pedal 1 does not change. Therefore, the driver can check the road surface condition when the anti-skid control or the like starts by adjusting the depression force of the brake pedal on a snowy road or the like.

It is a system diagram which shows the operation part of the brake-by-wire type brake device provided with the reaction force characteristic control apparatus which becomes one Example of this invention. It is a graph which shows the brake reaction force and stroke characteristic of the initial stage which starts depressing the brake pedal of the brake device. It is a graph which shows the brake reaction force and stroke characteristic from the brake pedal depressing start stage of the brake device to the final stage. It is a graph which shows the brake reaction force and stroke characteristic from the initial stage of the brake pedal depression of the brake device through the final stage to the final stage. It is a longitudinal cross-sectional view of the stroke simulator of the brake device, and shows a state where the distance S to the non-braking position of the receiving seat is set to the maximum value. It is a longitudinal cross-sectional view of the stroke simulator of FIG. 5, and shows the state where the stroke amount of the piston has reached the maximum value. It is a longitudinal cross-sectional view of the stroke simulator of the brake device, and shows a state where the distance S to the non-braking position of the receiving seat is set to a minimum value. It is a longitudinal cross-sectional view of the stroke simulator of FIG. 7, and shows a state where the stroke amount of the piston has reached the maximum value. It is a flowchart which shows the control program which the reaction force characteristic control unit of the brake device performs. It is a characteristic view showing the relationship between the manual mode consisting of hardware, medium and software, and the distance S defined according to the position of the stopper. FIG. 10 is a characteristic diagram showing a relationship between a vehicle speed V and a distance S defined according to the position of the stopper during the auto mode. It is a characteristic view which shows the relationship between a snow mode signal and the correction coefficient A. FIG. 6 is a characteristic diagram showing a relationship between a steering reaction force of power steering and a correction coefficient B. FIG. 5 is a characteristic diagram showing the relationship between lateral force and correction coefficient C. FIG. 6 is a characteristic diagram showing the relationship between engine braking force and correction coefficient D. FIG. 6 is a characteristic diagram showing a relationship between a brake operation duration time Tmr and a correction coefficient E. It is a graph showing the relationship between the brake reaction force and stroke characteristics of the brake device whose brake reaction force and stroke characteristics change according to the vehicle speed V. (a) shows the brake reaction force and stroke characteristics according to the vehicle speed V. (B) shows the relationship between the vehicle speed V and the reaction force characteristics of the brake pedal. In another Example, it is a characteristic view which shows the relationship between an estimated road surface friction coefficient and reaction force characteristic. It is a graph which shows the relationship between the brake operation continuation time Tmr of the brake device and the reaction force characteristic of the brake pedal, and (a) shows how the brake reaction force / stroke characteristic changes according to the brake operation continuation time Tmr. (B) shows the relationship between the brake operation duration Tmr and the reaction force characteristic of the brake pedal. It is a graph which shows a mode that the brake reaction force and stroke characteristic of a brake pedal change according to the steering reaction force of power steering. It is a graph which shows a mode that the brake reaction force and stroke characteristic of a brake pedal change according to the lateral force which arises during turning driving | running | working. It is a graph which shows a mode that the brake reaction force and stroke characteristic of a brake pedal change according to an engine brake force during normal brake operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 5,6 On-off valve 7 Switching valve 8 Stroke simulator 9 On-off valve 10 Liquid chamber 11 Cylinder 12 Port 13 Piston 14 Receiving seat 15 Elastic body (spring)
16 Elastic protrusion 17 Stopper 18 Rod 19 Elastic body (spring)
DESCRIPTION OF SYMBOLS 20 Air vent hole 21 Guide hole 22 Through-hole 23 Position control head 24 Gear tooth 25 Pinion 26 Shaft 27 Motor 28 Reaction force characteristic control unit 29 Pedal reaction force selection switch 30 Vehicle speed sensor 31 Snow mode switch 32 Power steering controller 33 Steering angle Sensor 35 ABS controller 36 Stroke sensor 37 VDC controller 38 Hydraulic pressure sensor 39 Engine brake force calculation unit

Claims (11)

In a brake device comprising a brake operator stroked by a driver's operation, and a brake reaction force / stroke characteristic changing means capable of changing a reaction force characteristic with respect to the stroke of the brake operator,
It includes a running state detection means for detecting a steering reaction force of a steering system operated by a driver ,
The brake reaction-stroke characteristic changing means, a brake, characterized in that the arrangement for changing the brake reaction force-stroke characteristic that the more brake reaction the steering reaction force based on the steering reaction force is large increases Device reaction force characteristic control device. In the reaction force characteristic control device according to claim 1,
The traveling state detection means detects vehicle speed,
The brake reaction force / stroke characteristic changing means is configured to change the brake reaction force / stroke characteristic so that the brake reaction force increases as the vehicle speed increases. In the reaction force characteristic control device according to claim 1 or 2,
The traveling state detection means estimates the friction coefficient between the wheel and the road surface,
The brake reaction force / stroke characteristic changing means is configured to change the brake reaction force / stroke characteristic so that the brake reaction force increases as the estimated friction coefficient decreases. apparatus. In the reaction force characteristic control device according to any one of claims 1 to 3,
The running state detecting means detects a driver's brake operation duration time,
The brake reaction force / stroke characteristic changing means is configured to change the brake reaction force / stroke characteristic so that the brake reaction force during the brake operation continues to gradually decrease as the brake operation duration time increases. The reaction force characteristic control device for the brake device. In the reaction force characteristic control device according to any one of claims 1 to 4,
The traveling state detection means detects the turning state of the vehicle,
The brake reaction force / stroke characteristic changing means is configured to change the brake reaction force / stroke characteristic so that the brake reaction force becomes larger as the turning state is a turning state that generates a larger lateral force. A reaction force characteristic control device for brake devices. In the reaction force characteristic control device according to any one of claims 1 to 5,
The traveling state detection means detects vehicle deceleration that does not depend on the operation of the brake operator,
The brake reaction force / stroke characteristic changing means is configured to change the brake reaction force / stroke characteristic so that the brake reaction force increases as the vehicle deceleration increases. . In the reaction force characteristic control device according to claim 6,
In addition to detecting the vehicle deceleration that does not depend on the operation of the brake operator, the running state detection means also detects a required braking force that results from the operation of the brake operator,
The brake reaction force / stroke characteristic changing means is configured to reduce the brake reaction force as the vehicle deceleration that does not depend on the operation of the brake operator increases when the required brake force is greater than a set value. A reaction force characteristic control device for a brake device, wherein the brake reaction force / stroke characteristic is changed. In the reaction force characteristic control device according to claim 6 or 7,
The reaction force characteristic control device for a brake device, wherein the vehicle deceleration not caused by the operation of the brake operator is a vehicle deceleration caused by an engine brake. In the reaction force characteristic control device according to claim 8,
The running state detection means determines the vehicle deceleration due to the engine brake from a deviation between a reference engine speed obtained from an engine throttle opening, a vehicle speed, and a total transmission ratio of the vehicle transmission system, and an actual engine speed. A reaction force characteristic control device for a brake device, characterized by being configured to estimate. In the reaction force characteristic control device according to any one of claims 1 to 9,
During the operation of the automatic brake force control means that automatically controls the brake force independently of the operation of the brake operator, the change of the brake reaction force / stroke characteristic by the brake reaction force / stroke characteristic changing means is prohibited. A reaction force characteristic control device for a brake device, characterized in that it is configured as described above. In the reaction force characteristic control device according to claim 10,
The automatic braking force control means includes at least one of an anti-skid control device for preventing a wheel from being locked and a vehicle dynamics control device for controlling a turning behavior of the vehicle. Control device.

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