JP2007045234A - Electric parking brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric parking brake device enhancing reliability. <P>SOLUTION: The electric parking brake device is provided with: a parking brake 10 driven by an electric actuator 20 and braking a wheel of a vehicle; a plurality of vehicle condition detection parts 44a, 44b detecting the condition of the vehicle and using the output for setting of target braking force of the parking brake 10; and a target braking force setting part 41 for comparing the outputs of the plurality of vehicle condition detection parts 44a, 44b and performing larger weighing addition than the output of the other vehicle condition detection part relative to the output of the vehicle condition detection part having strong tendency that the target braking force is increased to perform setting of the target braking force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric parking brake device provided in a vehicle such as an automobile.

The electric parking brake drives a parking brake that performs braking when the vehicle is parked or stopped using an electric actuator such as a motor (see, for example, Patent Document 1).
Since such an electric parking brake can be operated by an electric switch by a driver, the labor is reduced with respect to an operation by a general manual lever or a foot pedal, and automatically operates according to the state of the vehicle. By doing so, it is possible to prevent the vehicle from starting unintentionally due to AT creep, slope inclination, etc., and to contribute to the improvement of safety.

2. Description of the Related Art Conventionally, an electric parking brake includes a tilt sensor that detects the tilt of a vehicle and a master cylinder pressure sensor that detects a fluid hydraulic pressure of a main brake, and determines whether braking is necessary based on these outputs. (For example, refer to Patent Document 2).
In addition, an electric parking brake is known in which the braking force is set based on the output of an inclination sensor in order to prevent the vehicle from starting when the vehicle is parked on a slope or the like (for example, Patent Document 3). , 4).
JP 2004-51039 A JP 2002-242968 A Japanese Patent Laid-Open No. 10-24816 JP 2004-142517 A

In order to prevent the vehicle from starting to move on slopes, etc., the electric parking brake device sets the braking force during parking using a sensor such as a tilt sensor. Care must be taken not to occur.
An object of the present invention is to provide an electric parking brake device with improved reliability.

The present invention solves the above-described problems by the following means.
The invention of claim 1 is a parking brake driven by an electric actuator to brake the wheels of the vehicle, and a plurality of vehicle states in which the state of the vehicle is detected and its output is used for setting the target braking force of the parking brake. The outputs of the detection unit and the plurality of vehicle state detection units are compared, and the output of the vehicle state detection unit having a strong tendency to increase the target braking force is weighted higher than the outputs of the other vehicle state detection units. And a target braking force setting unit configured to set the target braking force.

According to a second aspect of the present invention, in the electric parking brake device according to the first aspect, the plurality of vehicle state detection units include a plurality of inclination sensors that respectively detect the inclination of the vehicle, and the target braking force setting unit is The electric parking brake device is characterized in that the target braking force is set based on an output of the plurality of inclination sensors that detect the inclination of the vehicle larger than other inclination sensors.
According to a third aspect of the present invention, in the electric parking brake device according to the first aspect, the plurality of vehicle state detection units correlate with a tilt sensor that detects a tilt of the vehicle and a braking force of a main brake of the vehicle. A main brake sensor for detecting a parameter, wherein the target braking force setting unit is configured to obtain a first braking force determined based on an output of the tilt sensor and a second braking force determined based on an output of the main brake sensor. The electric parking brake device is characterized in that the target braking force is set based on an output of a sensor having a larger braking force by comparing with a braking force.

  According to the present invention, a plurality of vehicle state detection units for detecting the vehicle state are provided, and the target braking force is set with an emphasis on the output of the vehicle state detection unit, which tends to increase the target braking force. Even if the vehicle has a malfunction and the vehicle inclination is detected to be small, the electric parking brake device prevents the target braking force from being set too low due to the output of the vehicle state detection unit. Reliability can be improved.

  The present invention solves the problem of providing an electric parking brake device with improved reliability by providing two systems of tilt sensors and setting a target braking force based on the output of the tilt sensor that detects a large tilt of the vehicle. did.

Hereinafter, an electric parking brake device according to a first embodiment to which the present invention is applied will be described.
FIG. 1 is a schematic diagram illustrating the configuration of the electric parking brake device according to the first embodiment. FIG. 2 is a block diagram showing a circuit configuration of the electric parking brake device.
The electric parking brake device includes a parking brake 10, an actuator unit 20, a battery 30, a controller 40, and a vehicle side unit 50.

  The parking brake 10 is a braking device that prevents the vehicle from moving when the vehicle is parked or the like, for example, by braking the wheels of the vehicle. The parking brake 10 is provided on each of the wheel hub portions of the left and right rear wheels of the vehicle. The parking brake 10 includes a brake drum (not shown) disposed on the inner diameter side of a rotor of a disc brake used as a foot brake (main brake) and a brake shoe (not shown) that pressurizes and contacts the inner diameter side of the brake drum during braking. I have.

The actuator unit 20 drives the shoe of the parking brake 10 and makes a transition between a braking state in which the parking brake 10 generates a braking force and a released state in which the braking force is not substantially generated. The actuator unit 20 includes a parking brake cable 21 and is fixed to, for example, a floor panel portion of the vehicle.
For example, the actuator unit 20 reduces the rotational force of a direct current (DC) motor by a reduction gear train, rotates a lead screw, and pulls or relaxes the parking brake cable 21 by an equalizer screwed to the lead screw. is there.

  The parking brake cables 21 are provided corresponding to the left and right parking brakes 10, respectively, and have flexibility so as to be deformed according to a stroke of a rear suspension (not shown). The parking brake cable 21 brings the parking brake 10 into a braking state by being pulled, and releases the parking brake 10 by being relaxed.

  Here, the actuator unit 20 has a function of adjusting the braking force of the parking brake 10 in the braking state by adjusting the tension applied to the parking brake cable 21. The tension is adjusted by changing the stroke with which the actuator unit 20 pulls the parking brake cable 21. For this reason, the actuator unit 20 is provided with a stroke sensor (not shown) for detecting the stroke.

The battery 30 is a secondary battery that is used as a main power source for a vehicle electrical system, and generates, for example, a DC 12V terminal voltage. The battery 30 includes a plus terminal 31 and a minus terminal 32.
The plus terminal 31 is connected to the controller 40 and the vehicle-side unit 50 via wiring (harness), respectively.
The minus terminal 32 is grounded with respect to the vehicle body.

The controller 40 includes an ECU 41, a relay 42, a manual operation switch 43, and a tilt sensor 44.
The ECU 41 includes a CPU that determines whether or not the parking brake 10 needs to be braked in response to an input from the manual operation switch 43 and the vehicle-side unit 50 and sets a target braking force to be described later.

  The relay 42 supplies driving power to the actuator unit 20 in accordance with a control signal output from the ECU 41. The relay 42 shifts the parking brake 10 from the braking state to the released state, and brakes from the released state. In order to make a transition to the state, a function of reversing the polarity of the drive power is provided, and the actuator unit 20 is in a neutral state where conduction with the actuator unit 20 is interrupted except when the actuator unit 20 is driven.

  The manual operation switch 43 is an operation unit through which a user inputs a manual selection operation in the braking state and the release state of the parking brake 10, and includes, for example, a push button switch mounted on an instrument panel (not shown) of the vehicle. . The manual operation switch 43 transmits the input to the ECU 41, and the ECU 41 controls the relay 42 according to this, and supplies driving power to the actuator unit 20 to drive the parking brake 10.

  The inclination sensor 44 is a vehicle state detection unit that detects the inclination of the vehicle mainly due to the road surface gradient and is used to determine the braking force of the parking brake 10 when the vehicle is stopped. For example, two systems are provided independently. ing. Hereinafter, each of the inclination sensors will be described with reference numerals 44a and 44b.

  The vehicle side unit 50 includes, for example, an engine control unit (ECU) that controls an engine of the vehicle, a transmission control unit (TCU) that controls a transmission (transmission), a VDC control unit that performs VDC control including ABS control, A vehicle integrated unit that comprehensively controls other electrical components is provided, and communicates with the controller 40 via a CAN communication system that is a type of in-vehicle LAN.

  The vehicle-side unit 50 sequentially provides the ECU 41 of the controller 40 with information such as, for example, engine speed, accelerator opening, transmission shift position, foot brake operation status, wheel rotation speed, and the like. When the ECU 41 determines that the vehicle has shifted from the running state to the stopped state based on these inputs, the ECU 41 determines that the parking brake 10 needs to be braked, and controls the relay 42 to supply drive power to the actuator unit 20. The parking brake 10 is shifted from the released state to the braking state. On the other hand, when the ECU 41 determines that the vehicle shifts from the stopped state to the traveling state, the ECU 41 shifts the parking brake 10 from the braking state to the released state.

Next, the operation at the time of setting the target braking force in the electric parking brake device of the first embodiment will be described.
FIG. 3 is a flowchart showing the operation at the time of setting the target braking force. Hereinafter, the steps will be described step by step.
(Step S01: Determination of manual operation)
The ECU 41 detects whether or not a manual operation for shifting the parking brake 10 from the released state to the braking state is input to the manual operation switch 43. If there is an operation, the process proceeds to step S03, and there is no operation. In this case, the process proceeds to step S02.

(Step S02: Automatic braking condition satisfaction determination)
The ECU 41 determines whether or not an automatic braking condition that is a condition for automatically shifting the parking brake 10 from the released state to the braking state is satisfied.
Here, the automatic braking condition includes, for example, the following items.
(A) Wheel speed = 0
(B) The brake lamp switch that is turned on in conjunction with the operation of the brake pedal is turned on. (C) Continues for the set time T (sec) in (a) and (b) above. If the automatic braking condition is satisfied In step S03, if not satisfied, the process returns to step S01 and the subsequent processing is repeated.

(Step S03: inclination sensor value n1, n2 confirmation)
The ECU 41 acquires and confirms the inclination sensor values n1 and n2 that are output according to the inclination of the vehicle detected by the inclination sensors 44a and 44b, respectively. Here, the inclination sensor values n1 and n2 are values having a positive correlation with the inclination angle of the vehicle.
(Step S04: inclination sensor value n1, n2 comparison (select high))
The ECU 41 compares the inclination sensor values n1 and n2 acquired in step S03. If n1 ≧ n2, the ECU 41 proceeds to step S05. If n1 <n2, the ECU 41 proceeds to step S06.

(Step S05: Reference inclination sensor value N = n1 setting)
The ECU 41 employs the inclination sensor value n1 output from the inclination sensor 44a as the reference inclination sensor value N that serves as a reference for setting the target braking force, and proceeds to step S07.
(Step S06: Reference inclination sensor value N = n2 setting)
The ECU 41 employs the inclination sensor value n2 output from the inclination sensor 44b as the reference inclination sensor value N, and proceeds to step S07.

(Step S07: N ≦ A judgment)
The ECU 41 compares the reference inclination sensor value N with a preset 10% gradient output value A. This 10% gradient output value A is an estimated value of the output of the tilt sensor when the vehicle is stopped on a ramp having a gradient of 10%, and will be described later as a 15% gradient output value B and a 20% gradient output value. C is the same.
If the reference inclination sensor value N ≦ 10% gradient output value A, the process proceeds to step S08. If the reference inclination sensor value N> 10% gradient output value A, the process proceeds to step S09.
(Step S08: Electric parking brake operation (braking force a))
The ECU 41 uses the braking force a set in advance as the target braking force to control the relay 42 to drive the actuator unit 20, shift the parking brake 10 from the released state to the braking state, and terminate the process.
This braking force a is set by multiplying the braking force (vehicle weight (MAX) × tilt amount converted value) necessary for stopping the vehicle on an inclined road having a gradient of 10% by a safety factor that is a predetermined coefficient. The same applies to braking force b and braking force c described later (corresponding to gradients of 15% and 20%, respectively).
The adjustment of the braking force by the actuator unit 20 is performed, for example, by changing the torque of the DC motor or the traction stroke of the actuator cable 21.

(Step S09: N ≦ B judgment)
The ECU 41 compares the reference inclination sensor value N with a preset 15% gradient output value B (B> A). If the reference inclination sensor value N ≦ 15% gradient output value B, the process proceeds to step S10. When the reference inclination sensor value N> 15% gradient output value B, the process proceeds to step S11.
(Step S10: Electric parking brake operation (braking force b))
The ECU 41 uses the braking force b (b> a) set in advance as a target braking force to control the relay 42 to drive the actuator unit 20 and shift the parking brake 10 from the released state to the braking state to complete the process. To do.

(Step S11: N ≦ C judgment)
The ECU 41 compares the reference inclination sensor value N with a preset 20% gradient output value C (C> B). If the reference inclination sensor value N ≦ 20% gradient output value C, the process proceeds to step S12. When the reference inclination sensor value N> 20% gradient output value C, the process proceeds to step S13.
(Step S12: Electric parking brake operation (braking force c))
The ECU 41 uses the braking force c (c> b) set in advance as a target braking force to control the relay 42 to drive the actuator unit 20 and shift the parking brake 10 from the released state to the braking state to complete the process. To do.

(Step S13: Electric parking brake operation (braking force d))
The ECU 41 uses the preset maximum braking force d (d> c) as a target braking force to control the relay 42 to drive the actuator unit 20 and shift the parking brake 10 from the released state to the braking state for processing. finish.
Such a maximum braking force d is set in consideration of, for example, the mechanical strength of the parking brake 10 and the actuator unit 20.

As described above, according to the first embodiment, if the target braking force is set based on the output of the two systems of the tilt sensors 44a and 44b on which the gradient is largely detected, the sensor in the system is Even if a malfunction such as a gain setting abnormality occurs and the inclination is detected lower than the actual value, the target braking force is prevented from being set too low due to the influence of the abnormal sensor, and the electric parking brake device Reliability can be improved.
Further, since the output of one of the tilt sensors is used for setting the target braking force by the select high, the output can be directly used for detecting the tilt without performing a complicated calculation or the like.
Furthermore, since the target braking force is selected from a plurality of preset values (a, b, c, d) according to the reference inclination sensor value N, the actuator unit 20 is driven to increase the braking force. Control to adjust can be simplified.

Next, a second embodiment of the electric parking brake device to which the present invention is applied will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
FIG. 4 is a schematic diagram illustrating a configuration of the electric parking brake device according to the second embodiment. FIG. 5 is a block diagram showing a circuit configuration of the electric parking brake device.

  The electric parking brake device of the second embodiment is different from the electric parking brake device of the first embodiment in that the tilt sensor 44 of the controller 40 is a single tilt sensor and the liquid connected to the VDC control unit of the vehicle side unit 50 is used. The configuration is different in that the output of the pressure sensor 51 is transmitted to the ECU 41 of the controller 40.

  The hydraulic pressure sensor 51 is a vehicle state detection unit that detects the pressure of the brake fluid that activates the main brake used when the vehicle is traveling as a parameter correlated with the braking force of the main brake of the vehicle. The hydraulic pressure sensor 51 is a pipe line connected to a master cylinder 52 having a booster that amplifies the hydraulic pressure generated by the driver operating the brake pedal using an intake pipe negative pressure (not shown). Provided in the department. Such a hydraulic pressure sensor 51 is provided in, for example, a hydraulic pressure control unit that adjusts the hydraulic pressure supplied to the piston portion of the main brake of each wheel for VDC control and ABS control.

  FIG. 6 is a flowchart illustrating an operation at the time of setting a target braking force in the electric parking brake device according to the second embodiment. Hereinafter, the steps will be described step by step. The process described below is performed subsequent to the process corresponding to steps S01 and S02 in the first embodiment.

(Step S21: Candidate braking force F1 calculation)
The ECU 41 calculates a candidate braking force F1 based on the output of the tilt sensor 44. The candidate braking force F1 is calculated by, for example, multiplying a braking force necessary for stopping the vehicle at a gradient detected by the inclination sensor 44 by a predetermined safety factor.

(Step S22: Stopping braking force A calculation)
Based on the output of the hydraulic pressure sensor 51, the ECU 41 calculates a braking force A generated by the main brake when the vehicle is stopped. The braking force A is, for example, the hydraulic pressure of the brake fluid detected based on the output of the hydraulic pressure sensor 51, the piston diameter and the number of brake calipers in each wheel, the area of the sliding surface portion between the brake pad and the brake rotor, and It can be calculated based on the friction coefficient or the like.
(Step S23: Candidate braking force F2 calculation)
The ECU 41 calculates a candidate braking force F2 by multiplying the braking force A obtained in step S22 by a predetermined coefficient.

(Step S24: Candidate braking force F1, F2 comparison (select high))
The ECU 41 compares the magnitudes of the candidate braking forces F1 and F2, and if F2 ≦ F1, the process proceeds to step S25, and if F2> F1, the process proceeds to step S26.
(Step S25: Electric parking brake operation (braking force F1))
The ECU 41 controls the relay 42 to drive the actuator unit 20 using the candidate braking force F1 set based on the output of the tilt sensor as the target braking force, and shifts the parking brake 10 from the released state to the braking state. Exit.

(Step S26: Candidate braking force F2, maximum braking force fmax comparison)
The ECU 41 compares the candidate braking force F2 with the maximum braking force fmax set in advance in consideration of the mechanical strength of the electric parking brake device. If the candidate braking force F2> the maximum braking force fmax, the ECU 41 performs step S27. If the candidate braking force F2 ≦ the maximum braking force fmax, the process proceeds to step S28.

(Step S27: Electric parking brake operation (braking force fmax))
The ECU 41 uses the maximum braking force fmax as the target braking force to control the relay 42 to drive the actuator unit 20 to shift the parking brake 10 from the released state to the braking state, and ends the process.
(Step S28: Electric parking brake operation (braking force F2))
The ECU 41 controls the relay 42 to drive the actuator unit 20 using the candidate braking force F2 set based on the output of the hydraulic pressure sensor as the target braking force, and shifts the parking brake 10 from the released state to the braking state. The process ends.

  As described above, according to the second embodiment, in addition to the same effects as those of the first embodiment, the main brake is controlled, for example, when the vehicle is stopped midway uphill and the AT creep force and gravity cancel each other. Even when the vehicle is stopped in a state where the power is low, by setting the target braking force according to the output of the tilt sensor, for example, when the target braking force is generated based on the output of the hydraulic pressure sensor Therefore, the braking force is not insufficient, and the reliability of the electric parking brake device can be further improved.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The first embodiment has, for example, two systems of tilt sensors, and the second embodiment has, for example, one system of tilt sensors and a main brake hydraulic pressure sensor. It is not limited, A sensor of a kind other than this may be used as a some vehicle state detection part, and it is good also as a structure which has a sensor of 3 systems or more. For example, two or more systems of tilt sensors and a main brake braking force sensor such as a hydraulic pressure sensor may be combined.
(2) In the second embodiment, the fluid pressure of the brake fluid is detected as a parameter correlated with the braking force of the main brake. However, the present invention is not limited to this. For example, the pedal effort applied to the brake pedal or the operation of the brake pedal You may make it detect a stroke.
(3) In the first embodiment and the second embodiment, the target braking force is set according to only the output of the pair of vehicle state detection units that tend to increase the target braking force (in this case, other vehicle state detection). However, the present invention is not limited to this, and the outputs of other vehicle state detection units may be used for setting the target braking force after relatively lightly weighted.
(4) When a plurality of inclination sensors are provided, a self-diagnosis function that determines that a defect has occurred in the inclination sensor when the output of one inclination sensor is lower than the output of the other inclination sensor with high frequency You may make it have. In addition, when it is recognized that such a phenomenon is caused by a malfunction in gain setting, the output gain of the tilt sensor may be automatically adjusted, thereby improving the fail-safe property.
(5) The parking brake of each embodiment uses a drum disposed on the inner diameter side of a brake disc for a foot brake, but the parking brake may be of other types, for example, a foot brake. The disc brake and drum brake for use and the friction material thereof may be shared and integrated with the parking brake.
(6) The parking brake of each embodiment uses an electric actuator fixed on the body side and drives the parking brake via a parking brake cable. However, the present invention is not limited to this, and for example, an electric actuator It can also be applied to a so-called built-in type electric parking brake that is provided on the wheel hub side and integrated with the parking brake.

It is the schematic which shows the structure of Example 1 of the electric parking brake apparatus to which this invention is applied. It is a block diagram which shows the circuit structure of the electric parking brake apparatus of FIG. It is a flowchart which shows the control at the time of the braking force setting in the electric parking brake apparatus of FIG. It is the schematic which shows the structure of Example 2 of the electric parking brake apparatus to which this invention is applied. It is a block diagram which shows the circuit structure of the electric parking brake of FIG. 6 is a flowchart showing control at the time of braking force setting in the electric parking brake device of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Parking brake 20 Actuator unit 30 Battery 40 Controller 41 ECU
42 Relay 43 Manual operation switch 44 Tilt sensor 50 Vehicle side unit

Claims (3)

A parking brake driven by an electric actuator to brake the wheels of the vehicle;
A plurality of vehicle state detectors that detect the state of the vehicle and whose output is used to set a target braking force of the parking brake;
The outputs of the plurality of vehicle state detection units are compared, and the output of the vehicle state detection unit having a strong tendency to increase the target braking force is weighted more than the outputs of the other vehicle state detection units, and the target control is performed. An electric parking brake device comprising: a target braking force setting unit configured to set power. In the electric parking brake device according to claim 1,
The plurality of vehicle state detection units include a plurality of inclination sensors that detect the inclination of the vehicle,
The electric parking brake characterized in that the target braking force setting unit sets the target braking force based on an output of the plurality of inclination sensors that detect the inclination of the vehicle larger than other inclination sensors. apparatus. In the electric parking brake device according to claim 1,
The plurality of vehicle state detection units include an inclination sensor that detects an inclination of the vehicle, and a main brake sensor that detects a parameter correlated with a braking force of a main brake of the vehicle,
The target braking force setting unit compares the first braking force obtained based on the output of the tilt sensor with the second braking force obtained based on the output of the main brake sensor, and the braking force is The electric parking brake device characterized in that the target braking force is set based on an output of a larger sensor.

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