JP2005088787A - Brake control device - Google Patents

Abstract

【Task】
Provided is a brake control device that can perform brake control at the time of stopping in accordance with a driver's intention.
[Solution]
The CPU 130 detects that the rotation speed of the wheel is zero, and the encoder 133 detects that the operation amount change of the brake pedal 5 is less than a predetermined amount when the wheel is braked. In such a case, in order to maintain the rotational position of the rotating shaft 103 of the electric motor 102, even if the driver unintentionally weakens the pedaling force of the brake pedal 5, the driving force is maintained to maintain the braking force of the wheels. It is possible to prevent unintended vehicle movement. Further, unnecessary energization of the motor can be prevented, energy saving can be achieved, and the problem of sound and vibration can be suppressed.
[Selection] Figure 3

Description

  The present invention relates to a brake control device, for example, a brake control device capable of performing a stable braking operation regardless of an operation of an operator.

  In a conventional hydraulic brake device in a vehicle, the brake pedal and the master cylinder are directly connected via a booster such as a booster, and the braking force of the wheels is generated by depressing the brake pedal. That is, in the normal brake range, the relationship is determined that the hydraulic pressure decreases when the pedal is returned and the hydraulic pressure increases when the pedal is depressed.

  By the way, in order to reduce a driver | operator's burden, the electric brake device which drives an actuator according to operation of a brake pedal and operates a master cylinder indirectly and gives a braking force to a wheel is developed. Here, in such an electric brake device, since the brake pedal and the master cylinder are not mechanically connected, it is necessary to energize the actuator according to the pedal operation amount to generate an appropriate braking force.

  However, at the time of normal braking during traveling, there is no particular problem even if the relationship between the pedal operation amount and the actuator movement amount is 1: 1. However, the pedal operation amount is not always constant when the vehicle is stopped. For example, the driver may unintentionally depress the brake pedal when the red signal or the like is stopped. In this case, the actuator is driven in a direction in which the braking force is increased. Although this will further increase the braking force of the wheels, it will not save energy if the actuator is energized repeatedly each time the vehicle is stopped. There is also a risk of giving. In particular, in recent years, the number of idle-stop vehicles that stop the engine when the red light stops is increasing, but stopping the engine lowers the background noise level when the vehicle stops, causing problems with sound and vibration. There is a fact that it is easy to manifest.

  In contrast to the above, there may be a case where it is necessary to increase the braking force regardless of the operation of the driver. For example, the idling speed of the engine may increase (idle-up function) to operate the air conditioner while the vehicle is stopped due to a red light or the like, but in the case of an AT vehicle, the creep force applied to the drive wheels increases. If the driver does not further depress the brake pedal, the vehicle may move forward. On the other hand, when stopping on an uphill, when the sum of the braking force and the creep force based on the operation of the brake pedal is just balanced against the force that the vehicle is going to fall by gravity, If the engine stops suddenly and the creep force becomes zero, the vehicle may move backward unless the driver further depresses the brake pedal.

On the other hand, Patent Document 1 discloses a technique for executing a braking force holding control by detecting a state from a vehicle speed sensor, a brake switch, an engine stop signal, or the like.
JP 2001-206206 A

  However, the technique disclosed in Patent Document 1 merely terminates the braking force holding mechanism by gradually decreasing the wheel cylinder pressure when the pedal force of the brake pedal is suddenly weakened. Cannot be solved.

  The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide a brake control device that can perform brake control at the time of stop according to the driver's intention.

The brake control device of the present invention is
An operation member operated by an operator;
An electric motor having a rotating shaft;
Operation detecting means for detecting an operation amount of the operation member;
A control device for driving and controlling the electric motor;
A braking device that brakes a wheel using power output from a rotating shaft of the electric motor;
Speed detecting means for detecting the rotational speed of the wheel,
In the control device, when the speed detecting means detects that the rotational speed of the wheel is zero, and the braking device brakes the wheel, the operation amount change of the operation member is less than a predetermined amount. When the operation detecting means detects this, a braking maintenance mode is set.

  According to the brake control device of the present invention, when the control device detects that the rotational speed of the wheel is zero and the speed detecting means brakes the wheel, the operation member When the operation detecting means detects that the operation amount change is less than a predetermined amount, the brake maintenance mode is set and the rotation position of the rotating shaft of the electric motor is maintained, so that the driver can operate unconsciously. Even when the pedaling force of a member (for example, a brake pedal) is weakened, the braking device maintains the braking force of the wheels, so that the movement of the vehicle not intended by the driver can be prevented. The “braking maintenance mode” refers to control that maintains the vehicle speed at zero when the change in the operation amount of the operation member is less than a predetermined amount, regardless of the operation amount of the operation member.

  The control device cancels the braking maintenance mode when the detecting means detects that a change in the operation amount of the operation member exceeds a predetermined amount, so that the driver is aware of the brake pedal for starting. When the foot is withdrawn from the wheel, the braking device immediately loses the braking force of the wheel, so that the vehicle can start smoothly.

  The brake device cancels the brake maintenance mode when the engine and the drive wheel are connected so that power can be transmitted and when the operator increases the engine speed by operating the accelerator. When the driver consciously depresses the accelerator pedal for starting, the braking device immediately loses the braking force of the wheels, so that the starting can be performed smoothly.

  In the state where the engine and the driving wheel are connected so as to be able to transmit power, the braking device does not cancel the braking maintenance mode when the speed of the engine increases without the operator operating the accelerator. Since the braking device is driven and controlled in the direction in which the braking force increases, the vehicle can be prevented from moving even when the engine speed increases in response to an idle increase or the like against the will of the operator.

  The brake device includes a tilt sensor that detects a tilt in the front-rear direction of the vehicle, and the braking device is configured to operate in the braking maintenance mode according to the tilt angle detected by the tilt sensor when the braking maintenance mode is set. Since the braking force of the braking device is changed, the vehicle can be prevented from moving against the will of the operator when the hill stops.

  When the speed detection means detects that the rotational speed of the wheel is no longer zero when the braking maintenance mode is set, the control device increases the braking force without releasing the braking maintenance mode. Since the braking device is driven and controlled in the direction, it is possible to prevent the vehicle from starting to move against the will of the driver due to disturbances such as idle up. However, when a disturbance such as an idle up can be detected in advance, it is desirable to increase the braking force before the wheel starts moving after detecting it.

  The brake control device includes a rotation element coupled to a rotation shaft of the electric motor (including a case where the brake control device is integrated with the rotation shaft), an axial movement element that applies hydraulic pressure to a master cylinder of the braking device, A ball screw mechanism that includes a rolling element disposed between the rotating element and the axially moving element, and that converts the rotational motion of the rotating element into the axial motion of the axially moving element; and the braking device Therefore, the braking force can be maintained without using an electromagnetic brake or the like.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a brake control device according to an embodiment of the present invention. In FIG. 1, the brake control device has a tandem master cylinder 1, and an actuator 100 is attached to the master cylinder 1. The configuration of the actuator 100 will be described later.

  The master cylinder 1 including the primary piston 1A and the secondary piston 1B is connected to a hydraulic circuit (not shown) that is configured by two hydraulic systems of X piping and adjusts the brake hydraulic pressure. A braking device for a wheel is constituted by a brake pad and a disk (not shown).

  Next, the actuator 100 will be described. 2 is a view of the configuration of FIG. 1 taken along line II-II and viewed in the direction of the arrow. In FIG. 1, the inner peripheral surface of the housing 101 attached to the vehicle body Vb with a bolt (not shown) A cylindrical stator 102b is fixed, and the stator 102b includes a rotor 102c. A rotor 102c is attached to the outer peripheral surface of the rotating shaft 103 that is rotatably supported with respect to the housing 101 by a bearing (not shown) so as to rotate integrally. A commutator 102f is disposed on the outer periphery of the rotating shaft 103 adjacent to the rotor 102c, and a brush 102e is slidably in contact with the outer peripheral surface. The electric motor 102 includes a stator 102b, a rotor 102c, a brush 102e, a commutator 102f, and a rotating shaft 103.

  In this embodiment, the rotating shaft 103 that also serves as a nut is hollow, and has a flange portion 103a that extends outward in the radial direction on the left end side in FIG.

  Further, an outer ring 105 of a one-way clutch is fixed to the inner peripheral surface of the housing 101 near the left end in FIG. As shown in FIG. 2, on the inner peripheral surface of the outer ring 105, there are formed a plurality of inclined surfaces 105a that become closer to the axis as it advances in one direction (clockwise in FIG. 2). Between the arranged thrust sleeves 120, rollable rollers 106 are respectively arranged. The outer ring 105, the roller 106, and the thrust sleeve 120 constitute a maintenance mechanism, that is, a one-way clutch.

  In FIG. 1, the thrust sleeve 120 includes a donut-shaped main body 120a and an outer shell 120b extending in the axial direction from the main body 120a, and the rollers 106 roll on the outer peripheral surface of the outer shell 120b. The right end surface in FIG. 1 of the main body 120a faces the flange portion 103a of the rotating shaft 130, and a friction member 122 is disposed between them.

  In FIG. 1, a screw shaft 111 passes through the rotation shaft 103. The screw shaft 111 has a male spline portion 111 a that engages with the female spline portion 101 a of the housing 101 at the right end in FIG. 2, and is thus movable only in the axial direction. A position sensor 125 that detects the amount of axial movement of the screw shaft 111 is provided in the housing 101, detects the amount of axial movement of the screw shaft, and a signal is input to the CPU 130 that is a control device.

  A screw groove 111b (only part of which is shown) is formed on the central outer peripheral surface of the screw shaft 111, while a screw groove 103b (part of the inner surface of the rotating shaft 103 faces the screw groove 111b). In the spiral space (transfer path) formed by the screw grooves 103b and 111b, a large number of balls 112 are arranged to roll freely. The nut 103 that is a rotating element, the screw shaft 111 that is an axially moving element, and the ball 112 constitute a ball screw mechanism.

  A pressing portion 111 c is provided at the left end of the screw shaft 111 in FIG. 1 and is in contact with the right end surface of the primary piston 1 A of the master cylinder 1. Since the secondary piston 1B and the primary piston 1A are urged to the right in FIG. 1 by the coil springs 1D and 1C, the pressing portion 111c is always urged to the right.

  The CPU 130 that is a control device is an operation detection unit that can detect the operation amount of the wheel speed sensor 131 that is a speed detection unit that detects the rotation speed of the wheel and the brake pedal 5 that is an operation member by a rotation angle. Signals from the encoder 133 are input, and the electric motor 102 is driven and controlled in response thereto. Note that a pressure sensor (not shown) for detecting the brake fluid pressure may be used instead of the position sensor 125 for detecting the axial movement amount of the screw shaft 111.

  FIG. 3 is a flowchart for explaining the operation of the present embodiment. The operation of the present embodiment will be described with reference to FIG. In step S101, if it is determined from the signal from the encoder 133 that the operation amount of the brake pedal 5 has exceeded the predetermined play amount, the process proceeds to step S102. If it is determined that the operation amount has not exceeded, the process returns to step S101.

  In step S102, the CPU 130 determines whether or not the vehicle speed has become zero based on the signal from the wheel speed sensor 131. If the CPU 130 determines that the vehicle speed is zero, the process proceeds to step S106. On the other hand, if it is determined that the vehicle speed is not zero, the process proceeds to step S103, and if it is determined that the brake pedal 5 is depressed according to the operation direction of the brake pedal 5, the process proceeds to step S104. If it is determined in step S103 that the brake pedal is moved in the direction of releasing, the process proceeds to step S105. In both step S104 and step S105, the electric motor 102 is driven according to the signal from the encoder 133, that is, according to the operation amount of the brake pedal 5. However, if the operation amount of the brake pedal 5 is constant, the electric motor 102 is not driven (the previous position is maintained).

  More specifically, in the case of step S104, the thrust sleeve 120 rotates in the direction of arrow A in FIG. 2 together with the rotating shaft 103. At this time, the roller 6 is formed between the thrust sleeve 120 and the outer ring 105. Therefore, the rotary shaft 103 is allowed to rotate.

  When the rotating shaft 103 rotates, the screw shaft 111 supported so as not to rotate with respect to the housing 101 is in a low friction state by the ball 112 rolling in a spiral space (transfer path) formed by the screw grooves 103b and 111b. Is pushed in the axial direction, that is, the rotational displacement is converted into the axial displacement. The axial movement of the screw shaft 111 causes the pressing portion 111c to move the primary piston 1A and the like to the left in FIG. 1, so that the master cylinder pressure increases and the wheel cylinder pressure increases accordingly. The brake pad is pushed so as to sandwich the disc or the like, and a braking force is applied to the wheel. During this vehicle braking, the CPU 130 adjusts the drive amount of the electric motor 102 in accordance with the operation amount of the brake pedal 5, so that an arbitrary braking force can be applied.

  On the other hand, when it progresses to step S105, the electric motor 102 is reversely rotated. More specifically, the CPU 130 supplies reverse electric power to the electric motor 102 to rotate the rotating shaft 103 in the reverse direction. In FIG. 2, if the rotation shaft 103 rotates in the direction of arrow B, the thrust sleeve 120 rotates in the direction of arrow B in FIG. 2 together with the rotation shaft 103. At this time, the roller 6 moves between the thrust sleeve 120 and the outer ring 105. The wedge-shaped air gap formed between the outer ring 105 and the thrust sleeve 120 is prohibited from rotating relative to the narrow side (lock position side).

  However, since the friction member 122 is interposed between the thrust sleeve 120 and the rotary shaft 103, the thrust sleeve 120 is fixed if the rotational torque of the rotary shaft 103 (electric motor 102) exceeds the friction force. Even if it is done, the rotating shaft 103 can rotate. As a result, the screw shaft 111 moves to the right in FIG. 1, so that the pressing portion 111 c does not press the primary piston 1 </ b> A, etc., so that the master cylinder pressure decreases, and the wheel cylinder pressure decreases accordingly. Therefore, the braking force of the wheels is weakened. During the vehicle braking, the CPU 130 adjusts the drive amount of the electric motor 102 in accordance with the operation amount of the brake pedal 5, so that an arbitrary braking force can be applied.

  In step S106, the CPU 130 starts the following braking maintenance mode. More specifically, in step S106, the braking force is maintained by maintaining the brake hydraulic pressure of the master cylinder 1. At this time, the electric motor 102 is stationary, but even in this case, the urging force of the coil springs 1C and 1D is acting on the screw shaft 111 via the pistons 1A and 1B of the master cylinder 1, so The directional displacement is converted into the rotational displacement of the rotating shaft 103. However, when the thrust sleeve 120 rotates in the direction of the arrow B, the roller 6 moves to the locked position (a narrow space between the outer ring 5) and the rotation of the thrust sleeve 120 is prevented by a so-called wedge action. Further, since a frictional force is generated between the thrust sleeve 120 and the rotating shaft 103 and the friction member 122 held between them, the rotation of the rotating shaft 103 is prevented. That is, it is not necessary to supply electric power to the electric motor 102 in order to maintain the brake hydraulic pressure of the master cylinder 1, and energy saving can be achieved. Further, since there is no unnecessary motor drive, problems relating to sound and vibration do not occur.

  Further, in step S107, the CPU 130 determines whether or not the change in the operation amount of the brake pedal 5 has become a predetermined value or more based on a signal from the encoder 133. Here, the predetermined value refers to a value that exceeds the angle change of the brake pedal 5 that is unconsciously performed by the driver, and can be obtained from an experiment or the like. Further, this value does not need to be a constant value, and can be changed depending on the absolute position of the brake pedal 5. If it is determined that the change in the operation amount of the brake pedal 5 is less than the predetermined value, the CPU 130 maintains the brake fluid pressure of the master cylinder 1 unless a brake maintenance mode release condition described later is satisfied. Can be maintained.

  However, the vehicle may start to move even if the brake fluid pressure of the master cylinder 1 is maintained, such as when the driving force is increased with respect to the braking force due to factors such as idle up. Further, it may be possible to step on an accelerator pedal (not shown) while stepping on the brake pedal 5 according to the driver's intention. Therefore, when a signal related to an increase in driving force from the engine controller 132 or the like is input to the CPU 130 in step S109, the process proceeds to step S110. On the other hand, if a signal relating to an increase in driving force is not input, the process returns to step S107 and the braking maintenance mode is continued.

  In step S110, it is determined whether or not the driver has intentionally increased the driving force, and the process proceeds to the next step. More specifically, when the CPU 130 receives an idle-up signal from the engine controller 132 or the like, it is determined that the driving force increases without the driver's operation (that is, regardless of the driver's will). The process proceeds to step S112. On the other hand, if the CPU 130 does not receive the idle up signal from the engine controller 132 or the like, it is determined that the driving force increases in accordance with the driver's operation (depressing the accelerator pedal) (that is, according to the driver's will) Proceeding to S111, the brake maintenance mode is canceled.

  When the driving force increases regardless of the driver's intention, in step S112, the current braking force is compared with the braking force with which the vehicle can be stopped when the driving force increases. If it is determined that the braking force is insufficient, the process proceeds to step S113. On the other hand, if it is determined that the vehicle can be stopped even if the driving force increases, the process returns to step S106 and the braking maintenance mode is continued. The relationship between the driving force and the braking force can be stored in advance in the CPU 130 through experiments, learning, etc. However, the fact that the driving force has won the braking force means that the wheel has rotated slightly. It can also be detected by the speed sensor 131.

  In step S113, the electric motor 102 is driven to increase the braking force regardless of whether or not the driver operates the brake pedal 5. More specifically, the CPU 130 drives the electric motor 102 in a direction to increase the brake hydraulic pressure of the master cylinder 1 by at least the increase in driving force calculated from the idle up signal from the engine controller 132, The brake maintenance mode is continued at the position.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. In the present embodiment, after entering the brake maintenance mode, the increase in creep due to engine idle-up is determined and the braking force is increased. For example, when entering the brake maintenance mode, creep due to engine idle-up is performed. In consideration of the increase in force or the decrease in creep force due to the engine stop, the electric motor can be driven to enter the braking maintenance mode with the braking force increased in advance. Further, for example, as shown in FIG. 4A, there is no need to interpose a friction member between the thrust sleeve 120 ′ and the rotating shaft 103 ′. Alternatively, as shown in FIG. The contact surface between the sleeve 120 ″ and the rotating shaft 103 ″ may be tapered. Furthermore, a tilt sensor that detects the tilt angle in the front-rear direction of the vehicle is provided, and the braking force in the braking force maintenance mode (a control that is increased or decreased according to disturbance such as idle up) according to the tilt angle detected by the tilt sensor. (Including power) can also be changed.

It is a schematic block diagram of the brake control apparatus concerning this Embodiment. It is the figure which cut | disconnected the actuator 100 by the II-II line | wire and looked at the arrow direction. It is a flowchart figure which shows operation | movement of the brake control apparatus concerning this Embodiment. It is a figure which shows the modification of an actuator.

Explanation of symbols

1 Master cylinder 5 Brake pedal 100 Actuator 101 Housing 102 Electric motor 103 Rotating shaft (nut)
106 Roller 111 Screw shaft 112 Ball 120 Thrust sleeve 130 CPU
131 Wheel speed sensor 132 Hydraulic pressure sensor 133 Encoder

Claims (7)

An operation member operated by an operator;
An electric motor having a rotating shaft;
Operation detecting means for detecting an operation amount of the operation member;
A control device for driving and controlling the electric motor;
A braking device that brakes a wheel using power output from a rotating shaft of the electric motor;
Speed detecting means for detecting the rotational speed of the wheel,
In the control device, when the speed detecting means detects that the rotational speed of the wheel is zero, and the braking device brakes the wheel, the operation amount change of the operation member is less than a predetermined amount. When the operation detecting means detects this, a brake maintenance mode is set.   2. The brake according to claim 1, wherein the braking device cancels the braking maintenance mode when the operation detecting unit detects that a change in an operation amount of the operation member exceeds a predetermined amount. 3. Control device.   The braking device cancels the braking maintenance mode when the engine increases the engine speed by operating the accelerator in a state where the engine and the driving wheel are connected to transmit power. The brake control device according to claim 1 or 2.   In the state where the engine and the driving wheel are connected so as to be able to transmit power, the braking device does not cancel the braking maintenance mode when the speed of the engine increases without the operator operating the accelerator. The brake control device according to any one of claims 1 to 3, wherein the braking device is drive-controlled in a direction in which a braking force increases.   The brake device includes a tilt sensor that detects a tilt in the front-rear direction of the vehicle, and the braking device is configured to operate in the braking maintenance mode according to the tilt angle detected by the tilt sensor when the braking maintenance mode is set. The brake control device according to any one of claims 1 to 4, wherein a braking force of the braking device is changed.   When the speed detection means detects that the rotational speed of the wheel is no longer zero when the braking maintenance mode is set, the control device increases the braking force without releasing the braking maintenance mode. The brake control device according to any one of claims 1 to 5, wherein the brake device is driven and controlled in a direction. The brake control device includes:
A rotating element coupled to a rotating shaft of the electric motor; an axially moving element that applies hydraulic pressure to a master cylinder of the braking device; and a rolling element disposed between the rotating element and the axially moving element. A ball screw mechanism that converts rotational movement of the rotating element into axial movement of the axial movement element;
The brake control device according to claim 1, further comprising a maintenance mechanism that maintains a position of a rotation shaft of the electric motor regardless of a reaction force from the braking device.

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