JP6018561B2 - Electric parking brake system - Google Patents

Description

  The present invention relates to an electric parking brake system.

  As a conventional electric parking brake system, for example, one described in Patent Document 1 below is known. In the electric parking brake system described in Patent Document 1, when the vehicle is kept stopped on an ascending road surface and when the vehicle is kept stopped on a descending road surface, the road surface slope has the same magnitude. However, the index load of the brake cable that drives the drum brake mechanism is controlled to have different magnitudes.

JP 2008-68843 A

  Here, in the above prior art, since the change in the posture of the vehicle that occurs during braking is not taken into consideration, the change in the posture of the vehicle occurs during braking and the inclination in the pitching direction of the vehicle (the gradient of the vehicle) increases. In the subsequent braking, the vehicle may not be kept stationary.

  That is, for example, when the vehicle is stopped on a slope, the electric parking brake is operated and braked (hereinafter simply referred to as “braking”), and then the vehicle is lifted with a jack or the like to make the posture substantially horizontal, the braking is performed. Suppose you release it. In this case, normally, before the vehicle is lowered to the slope, the braking is performed again so that the vehicle can maintain the stop state on the slope. However, since the brake load in the second braking is a brake load corresponding to the vehicle posture when the second braking is started (that is, the substantially horizontal vehicle posture), the vehicle is lowered to the slope. Sometimes, the brake load is lower than the load necessary for stopping, and as a result, the vehicle may not be able to maintain the stopped state.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric parking brake system that can secure a brake load necessary for stopping even when a change in the posture of the vehicle occurs.

  In order to solve the above problems, an electric parking brake system according to the present invention includes an electric parking brake device for braking a vehicle, a brake load control means for controlling a brake load in the electric parking brake device, and an attitude change of the vehicle. And a brake load control unit configured to set a first brake load as a brake load according to the vehicle posture when braking of the electric parking brake device is started. In the case where a change in posture while the vehicle is being braked by the first brake load is detected by the posture detecting means, the first brake load is applied when the electric parking brake device is braked again after the braking is released. And executing the second braking control that sets the second brake load as a brake load. That, characterized in that.

  According to this electric parking brake system, for example, even when a change in the attitude of the vehicle occurs during braking on a slope as described above, the second brake load that is equal to or greater than the first brake load is set as the brake load in the subsequent braking. Therefore, it is possible to secure a brake load necessary for stopping, and as a result, it is possible to keep the vehicle stopped.

  The electric parking brake device includes an actuator and a parking brake mechanism that is driven by the actuator via a brake cable, and the second brake load is a maximum cable index at which the actuator can drive the parking brake mechanism. It may be a load. By setting the maximum cable index load as the second brake load, the stop state of the vehicle can be reliably maintained.

  The vehicle further includes a travel detection unit that detects the start of travel of the vehicle, and the brake load control unit may cancel the setting of the second brake load in the second braking control when the travel detection unit detects the start of travel. Good. In this case, the load applied to the electric parking brake device can be reduced.

  In addition, an operation unit that switches between an operation state and a non-operation state of the brake load control unit is provided, and the brake load control unit is configured to change the second brake load in the second brake control when the operation unit is switched to the non-operation state. Settings may be retained. When the vehicle load changes when the brake load control means is inactive, various functions such as detecting the wheel rotation and increasing the brake load (increasing and pulling the brake cable) are also disabled. Since it becomes a state, there exists a possibility that the brake load required for a stop cannot be ensured. On the other hand, in this invention, since the setting of a brake load is hold | maintained with a 2nd brake load, the brake load required for a stop can be ensured.

  According to the present invention, it is possible to ensure the brake load necessary for stopping even when the posture of the vehicle changes.

It is the schematic which shows the structure of the electric parking brake system which concerns on one Embodiment. It is a flowchart explaining operation | movement of the electric parking brake system of FIG. It is a timing chart explaining an example in the case of stopping a vehicle using the electric parking brake system of FIG. It is a schematic diagram explaining the attitude | position change of a vehicle.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same or corresponding elements, and duplicate descriptions are omitted.

  FIG. 1 is a schematic diagram showing the configuration of an electric parking brake system according to an embodiment of the present invention. As shown in FIG. 1, an electric parking brake system 1 according to this embodiment is mounted on a vehicle V and includes an electric parking brake device (Electronic Parking Brake: EPKB) 10, a rotation sensor 20, and a G sensor. 30, a PKB operation switch 50, an ignition switch 60, and an ECU (Electronic Control Unit) 70. In addition, the vehicle V includes an outrigger 40.

  Examples of the vehicle V include large vehicles such as trucks, buses, and heavy machinery, and medium-sized vehicles. The applied vehicle V is not limited to these, and may be a normal passenger car, a small vehicle, a light vehicle, or the like.

  The electric parking brake device 10 is an electric parking brake device for braking the vehicle V, and includes an actuator 11, a brake cable 12, and a PKB (Parking Brake: parking brake mechanism) 13. In the electric parking brake device 10, the actuator 11 is actuated and the brake cable 12 is pulled with a predetermined index load to drive the PKB 13 and apply a desired braking force to the wheels H of the vehicle V.

  The actuator 11 includes a motor, a cable winding unit (not shown), and the like. The actuator 11 performs the pulling operation of the brake cable 12 by converting the rotational motion of the motor into linear motion at the cable winding portion. The actuator 11 is electrically connected to the ECU 70, and the index load of the brake cable 12 is controlled by the ECU 70.

  The brake cable 12 is a wire that is connected to the actuator 11 and the PKB 13 and transmits an index load by the motor of the actuator 11 to the PKB 13. In the illustrated example, the brake cable 12 extends forward from the actuator 11 between the driver seat D and the passenger seat P in the vehicle V, and then bends so as to pass through the front side and the right side of the driver seat D. It extends rearward and is connected to the PKB 13.

  The PKB 13 employs a center brake drum brake or the like, and is installed behind the transmission 2. For example, the PKB 13 presses the shoe against the drum according to the index of the brake cable 12, thereby restraining the propeller shaft 3. The PKB 13 is not limited in its configuration and method, and may be used as a service brake mechanism installed in the wheel H, or a parking brake mechanism different from the service brake mechanism may be used in the wheel H. It may be built-in. The PKB 13 may have an air brake mechanism that uses compressed air for its operation.

  The rotation sensor 20 detects rotation of the wheel H (here, the rear wheel) of the vehicle V, and a wheel speed sensor such as an ABS sensor is used, for example. The rotation sensor 20 is electrically connected to the ECU 70 and outputs the detected value to the ECU 70.

  The G sensor 30 is an acceleration sensor that detects acceleration acting on the vehicle V. Here, the G sensor 30 detects acceleration in the front-rear direction of the vehicle V. The G sensor 30 is electrically connected to the ECU 70 and outputs the detected value to the ECU 70. Note that the G sensor 30 only needs to be able to detect a change in posture of the vehicle V, and may detect acceleration in the vertical direction of the vehicle V, for example.

  The outrigger 40 is a mechanism having a jack function for lifting the vehicle V. In the present embodiment, one outrigger 40 is provided on each of the front, rear, left and right sides of the vehicle V. Each of the outriggers 40 is configured to be able to expand and contract in the vertical direction of the vehicle V by, for example, hydraulic pressure. According to the outrigger 40, for example, the vehicle V can be lifted by extending and the vehicle posture of the vehicle V can be changed.

  The PKB operation switch 50 is for operating the electric parking brake device 10, and is electrically connected to the ECU 70. This PKB operation switch 50 operates the actuator 11 by transmitting a signal to the ECU 70 so that the electric parking brake device 10 is operated or released when the driver is switched ON or OFF by, for example, a driver. Let

  The ignition switch 60 is a power switch of the electrical device in the vehicle V and is provided in the vicinity of the driver seat D. The ignition switch 60 of the present embodiment is electrically connected to at least the ECU 70, and switches on or off the power supply to the ECU 70, for example, by switching on or off by a driver.

  ECU70 is a control part which controls operation | movement of the electric parking brake apparatus 10, for example, is comprised by the computer containing CPU (Central Processing Unit), ROM (Read OnlyMemory), RAM (Random Access Memory). The ECU 70 includes a brake load control unit 71, a vehicle posture change detection unit 72, and a travel start detection unit 73.

  The brake load control unit 71 controls the operation of the actuator 11 based on the detection value of the rotation sensor 20, the detection value of the G sensor 30, and the signal from the PKB operation switch 50, and controls the brake load in the electric parking brake device 10. .

  The vehicle posture change detection unit 72 determines and detects the posture change of the vehicle V being braked by the electric parking brake device 10 based on the detection value of the G sensor 30. Specifically, the vehicle posture change detection unit 72 determines that there has been a change in the posture of the vehicle V when the detection value of the G sensor 30 during the first braking control has changed more than a predetermined value.

  The travel start detection unit 73 detects the travel start of the vehicle V based on the detection value of the rotation sensor 20. Specifically, the travel start detection unit 73 calculates the vehicle speed of the vehicle V based on the detection value of the rotation sensor 20, and detects the start of travel of the vehicle V when the vehicle speed of the vehicle V exceeds a predetermined vehicle speed. To do.

  For example, when the PKB operation switch 50 is switched ON and braking by the electric parking brake device 10 is started, the ECU 70 sets the first brake load corresponding to the posture of the vehicle V at that time as the brake load. To do. Further, when the posture change while the vehicle V is being braked by the first brake load is detected by the vehicle posture change detection unit 72, the PKB operation switch 50 is switched ON and braking by the electric parking brake device 10 is performed. Is started, a second brake load equal to or higher than the first brake load is set as a brake load (details will be described later).

  Next, the operation of the electric parking brake system 1 will be described with reference to FIG. FIG. 2A is a flowchart for explaining an example of a brake load setting operation in accordance with a change in the posture of the vehicle V.

  First, as shown in FIG. 2A, when the PKB operation switch 50 is switched to ON in step S1, a signal related to a braking start request for operating the electric parking brake device 10 is output to the ECU. As a result, in step S2, the first parking control is executed by the electric parking brake device 10. Specifically, the brake load control unit 71 sets a first brake load corresponding to the posture of the vehicle V based on the detection value of the G sensor 30 as the brake load. Then, the actuator 11 is operated so that the brake load becomes the first brake load and the brake cable 12 is pulled (indexed), whereby the PKB 13 is driven.

  Subsequently, in step S3, when the PKB operation switch 50 is switched to OFF, a signal related to a brake release request for disabling the electric parking brake device 10 is output to the ECU 70. As a result, in step S4, the first braking control by the electric parking brake device 10 is terminated. Specifically, in the electric parking brake device 10, the actuator 11 is actuated to loosen the index of the brake cable 12, and the restraint of the propeller shaft 3 in the PKB 13 is released.

  Subsequently, when the PKB operation switch 50 is switched to ON again in step S5, a signal related to a braking start request for operating the electric parking brake device 10 is output to the ECU 70. At the same time, in step S6, the vehicle attitude change detection unit 72 determines whether or not the attitude of the vehicle V has changed during the first braking control. This determination is performed based on, for example, whether or not the detection value of the G sensor 30 has changed. In the present embodiment, when the detected value of the G sensor 30 during the first braking control has changed more than a predetermined value, it is determined that the attitude of the vehicle V has changed. If it is determined that the posture of the vehicle V has changed, the process proceeds to step S7. If not, the process proceeds to step S8.

  In step S <b> 7, the second braking control is executed by the electric parking brake device 10. Specifically, the brake load control unit 71 sets a second brake load that is equal to or greater than the first brake load as the brake load. The second brake load here is the maximum cable index load that allows the actuator 11 to drive the PKB 13. Then, the actuator 11 is operated so that the brake load becomes the second brake load and the brake cable 12 is pulled, whereby the PKB 13 is driven. On the other hand, in step 8, the first parking control described above is executed by the electric parking brake device 10.

  FIG. 2B is a flowchart for explaining an example of the setting release operation of the second brake load based on the detection of the start of traveling. As shown in FIG. 2B, in the electric parking brake system 1, the setting of the second brake load in the second braking control can be canceled with the start of traveling of the vehicle V as a trigger.

  That is, first, in step S9, the ECU 70 determines whether or not the vehicle V has started to travel. Specifically, the travel start detection unit 73 calculates the vehicle speed of the vehicle V based on the detection value of the rotation sensor 20, and determines that the vehicle V has started traveling when the vehicle speed of the vehicle V is equal to or higher than a predetermined vehicle speed. The When it is determined that the vehicle V has started running, the process proceeds to step 10.

  In step S10, the brake load control unit 71 cancels the setting of the second brake load in the second brake control described above. As a result, when the electric parking brake device 10 is subsequently braked, the first braking control described above is executed, and the first brake load corresponding to the posture of the vehicle V based on the detection value of the G sensor 30 is used as the brake load. Will be set.

  Next, an example of stopping the vehicle V using the electric parking brake system 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a timing chart for explaining an example when the vehicle V is stopped using the electric parking brake system 1, and FIG. 4 is a schematic diagram for explaining the posture change of the vehicle V.

  In the following description, when the vehicle V as an aerial work vehicle performs work on a slope, the vehicle V is stopped on the slope and braked, and then lifted by the outrigger 40 to make the posture of the vehicle V substantially horizontal. In this case, it is assumed that the braking is released for some reason. In addition, it is assumed that the vehicle V is braked again so that the vehicle V can be stopped on the slope before the vehicle V is lowered onto the slope.

  First, as shown in FIG. 3, the vehicle V traveling on a slope with a certain slope is decelerated by the driver's foot brake operation or the like, and stopped at time t1 (see FIG. 4 (a)). At time t2, the PKB operation switch 50 is switched to ON, whereby the electric parking brake device 10 starts the first braking control described above.

  Specifically, a signal related to a braking start request for operating the electric parking brake device 10 is output from the PKB operation switch 50 to the ECU 70. Then, the brake load control unit 71 sets the first brake load according to the posture of the vehicle V (the detection value of the G sensor 30) as the brake load, and the vehicle V is braked with the first brake load (time). t3).

  Subsequently, at time t <b> 4, the ignition switch 60 is switched off, and the power supply to the ECU 70 is cut off. And in the period of time t5-t6, the vehicle V is jacked up so that it may become a substantially horizontal attitude | position. For example, as shown in FIG. 4B, the vehicle V is lifted by extending the outrigger 40 provided in the vehicle V.

  Subsequently, at time t7, the ignition switch 60 is switched ON, and the ECU 70 is energized again. At time t <b> 8, the PKB operation switch 50 is switched to OFF, whereby a signal related to a brake release request that deactivates the electric parking brake device 10 is output to the ECU 70. As a result, the first braking control described above by the electric parking brake device 10 is terminated.

  At time t <b> 9, the PKB operation switch 50 is switched to ON again, whereby a signal related to a braking start request for operating the electric parking brake device 10 is output to the ECU 70. At this time, since the change in the detected value of the G sensor 30 is more than a predetermined value due to the change in posture of the vehicle V during the period from time t5 to time t6, the vehicle V during the first braking control is detected by the vehicle posture change detection unit 72. Is detected, and the electric parking brake device 10 starts the second braking control described above.

  Specifically, the brake load control unit 71 sets a second brake load equal to or higher than the first brake load as a brake load of the second brake control, and the vehicle V is braked with the second brake load (time). t10).

  Subsequently, at time t <b> 11, the ignition switch 60 is switched off, and the power supply to the ECU 70 is cut off. At this time, the brake load control unit 71 maintains the brake load setting as the second brake load. During the period from time t12 to t13, the vehicle V is jacked down and lowered onto the slope. For example, as shown in FIG. 4C, the lifted vehicle V is lowered by reducing the outrigger 40 provided in the vehicle V.

  By the way, normally, since the brake load is a load corresponding to the posture of the vehicle V when the braking is started, when the electric parking brake device 10 is reactivated at the time t9, A value corresponding to the posture of the vehicle V (that is, a substantially horizontal vehicle posture) is set (see the broken line in FIG. 3). In this case, when the vehicle V is lowered on the slope at the time t12 to t13, there is a possibility that the brake load is lower than the load necessary for stopping and the vehicle V cannot be stopped. In this regard, as described above, the brake load in the present embodiment is set to the second brake load that is equal to or greater than the first brake load and the second braking control is executed. Therefore, even when the vehicle V is lowered on a slope. The brake load necessary for stopping can be secured.

  Subsequently, at time t14, the ignition switch 60 is switched ON, and the ECU 70 is energized again. At time t <b> 15, the PKB operation switch 50 is switched to OFF, whereby a signal related to a brake release request for disabling the electric parking brake device 10 is output to the ECU 70. As a result, the above-described second braking control by the electric parking brake device 10 is ended (see time t16).

  Thereafter, during the period from time t17 to t18, the vehicle V starts to travel and the vehicle speed is increased. When the vehicle speed of the vehicle V is equal to or higher than a predetermined vehicle speed, the traveling start detection unit 73 determines that the vehicle V has started traveling. The brake load control unit 71 cancels the setting of the second brake load in the second braking control according to the determination of the start of travel.

  Subsequently, during a period from time t17 to time t19, the vehicle V travels from a slope to a flat road, and the posture of the vehicle V is changed to a substantially horizontal posture. And in the period of time t19-t20, the vehicle V decelerates by a driver | operator's foot brake operation etc., and stops. At time t21, the PKB operation switch 50 is switched to ON, and a signal related to a braking start request for operating the electric parking brake device 10 is output to the ECU 70.

  In the braking start request at time t21, since the setting of the second brake load has already been canceled, the electric parking brake device 10 starts the first braking control described above. Specifically, the third brake load corresponding to the substantially horizontal posture of the vehicle V is set as the brake load, and the vehicle V is braked with the third brake load (see time t22).

  As described above, in the electric parking brake system 1 of the present embodiment, when a change in the posture of the vehicle V is detected during braking by the first brake load, when the braking is performed again after the braking is released, the first brake load The above second brake load is set as the brake load. Accordingly, it is possible to secure a brake load necessary for stopping at the time of the second braking, to keep the vehicle V in a stopped state, and to suppress the vehicle V from sliding down the slope.

  In the present embodiment, the maximum cable index load that can drive the PKB 13 by the actuator 11 is set as the second brake load. Thereby, the stop state of the vehicle V can be maintained reliably.

  In this embodiment, when the start of traveling of the vehicle V is detected, the brake load control unit 71 cancels the setting of the second brake load in the second braking control. Therefore, the load applied to the electric parking brake device 10 can be reduced.

  Incidentally, for example, various functions such as detecting the rotation of the wheel to increase the brake load (increase and pull the brake cable) may be mounted on the vehicle V. However, in this case, at the time t12 to t14 when the ignition switch 60 is turned off and the power supply to the ECU 70 is cut off, these various functions are inoperative, so that the brake load necessary for stopping cannot be secured. Is concerned. In contrast, in the present embodiment, since the second brake load can be maintained even when the ignition switch 60 is switched to OFF, the vehicle V can sufficiently apply the brake load necessary for stopping at the times t12 to t14. Can be secured.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention can be modified without departing from the scope described in the claims or applied to other embodiments. May be.

  For example, in the above embodiment, jack-up and jack-down for changing the posture of the vehicle V are performed by the outrigger 40, but may be performed by a hydraulic jack for maintenance or the like. Further, the posture of the vehicle V when jacked up may be a posture that is not substantially horizontal.

  In addition, the example shown in FIG. 3 includes the switching operation of the ignition switch 60 during the first braking control. For example, the switching operation by the ignition switch 60 (the operation state and non-operation of the brake load control means by the operation unit). In some cases, switching to a state is not performed.

  DESCRIPTION OF SYMBOLS 1 ... Electric parking brake system, 10 ... Electric parking brake device, 11 ... Actuator, 12 ... Brake cable, 13 ... PKB (parking brake mechanism), 20 ... Rotation sensor (travel detection means), 30 ... G sensor (Attitude detection means) ), 60 ... ignition switch (operation part), 71 ... brake load control part (brake load control means), 72 ... vehicle posture change detection part (posture detection means), 73 ... travel start detection part (travel detection means), V …vehicle.

Claims (4)

An electric parking brake device for braking the vehicle;
Brake load control means for controlling a brake load in the electric parking brake device;
Posture detecting means for detecting a change in posture of the vehicle,
The brake load control means includes
A first braking control for setting, as the brake load, a first brake load corresponding to a posture of the vehicle when braking of the electric parking brake device is started;
In the case where the posture change while the vehicle is being braked by the first brake load is detected by the posture detection means, the brake is released again by the electric parking brake device after the braking is released, An electric parking brake system that executes a second braking control that sets a second brake load that is equal to or greater than the first brake load as the brake load. The electric parking brake device has an actuator and a parking brake mechanism driven by the actuator via a brake cable,
The electric parking brake system according to claim 1, wherein the second brake load is a maximum cable index load with which the actuator can drive the parking brake mechanism. Comprising travel detection means for detecting the start of travel of the vehicle;
The electric brake according to claim 1 or 2, wherein the brake load control means cancels the setting of the second brake load in the second braking control when the travel start is detected by the travel detection means. Parking brake system. An operation unit for switching between an operating state and a non-operating state of the brake load control means;
The brake load control means according to any one of claims 1 to 3, wherein the brake load control means holds the setting of the second brake load in the second brake control when the operation unit is switched to the non-operating state. The described electric parking brake system.

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