JP2008056090A - Electric parking brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric parking brake control device capable of properly performing the drive control of an actuator even at low temperatures. <P>SOLUTION: The electric parking brake control device 40 for controlling an electric actuator 20 to drive a parking brake 10 comprises a power supply unit 42 which supplies the power to the electric actuator 20 and stops the power supply when the current running in the electric actuator 42 reaches the set value, atmospheric temperature detection units 44, 62 for detecting parameters related to the atmospheric temperature at the electric actuator 20, and a set current changing unit 41 for changing the set current value in the power supply unit 42 based on the output of the atmospheric temperature detection unit 44. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an electric parking brake 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.
Since such an electric parking brake can be operated by an electric switch by a driver, labor is reduced with respect to an operation by a general manual lever or a foot pedal.

The electric parking brake is required to appropriately control the driving force of the actuator in order to generate a braking force without excess or deficiency.
Conventionally, an electric parking brake is known in which an upper limit value of a current to be supplied to an actuator is set, and power supply is stopped when the current reaches an upper limit value while the actuator is being driven (for example, Patent Documents). 1).
JP 2005-67409 A

However, in the case of the conventional technology that controls the driving of the actuator based on the current value, when the vehicle is used at a low temperature, the change in the electrical characteristics and the hardening of the grease used for the actuator, the driving mechanism, etc. In some cases, the actuator load increases and a predetermined braking force cannot be obtained even if power is supplied up to a set current value.
An object of the present invention is to provide an electric parking brake control device that appropriately performs drive control of an actuator even at low temperatures.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, in the electric parking brake control device that controls the electric actuator that drives the parking brake, when electric power is supplied to the electric actuator and the current supplied to the electric actuator reaches a set current value The power supply unit for stopping the supply of power, an ambient temperature detection unit for detecting a parameter correlated with the ambient temperature in the electric actuator, and the setting in the power supply unit based on the output of the ambient temperature detection unit An electric parking brake control device comprising: a set current value changing unit that changes a current value.

According to a second aspect of the present invention, in the electric parking brake control device according to the first aspect, the set current value changing unit is configured to output the set current value when a parameter correlated with the ambient temperature satisfies a predetermined low temperature condition. This is an electric parking brake control device characterized in that
According to a third aspect of the present invention, in the electric parking brake control device according to the second aspect, the set current value changing unit is configured to output the set current value when a parameter correlated with the ambient temperature satisfies a predetermined low temperature condition. Is set based on a parameter correlated with the ambient temperature.
According to a fourth aspect of the present invention, in the electric parking brake control device according to any one of the first to third aspects, the parameters correlated with the ambient temperature are an outside air temperature, an indoor temperature, an engine exhaust temperature, an engine The electric parking brake control device is detected based on at least one of cooling water temperature.

  According to the present invention, since the set current value is changed based on the parameter correlated with the ambient temperature in the electric actuator, the set current value is set in the low temperature state where a predetermined braking force cannot be obtained with the same set current value as that at room temperature. By improving the current value, sufficient actuator output and braking force of the parking brake can be ensured, and actuator drive control can be performed appropriately.

  An object of the present invention is to provide an electric parking brake control device that appropriately performs actuator drive control even at low temperatures, based on the outside temperature and the difference between the outside temperature and the actuator ambient temperature. If it was determined that the current value was increased, the set current value was increased.

Embodiments of an electric parking brake device including an electric parking brake control device to which the present invention is applied will be described below.
FIG. 1 is a block diagram illustrating a configuration of an electric parking brake device according to an embodiment.

In the embodiment, the vehicle is an automobile such as a passenger car.
The electric parking brake device includes a parking brake 10, an actuator unit 20, a battery 30, a controller 40, an operation switch 50, a vehicle side unit 60, and a warning light 70.

  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. It is a so-called drum-in-disc type.

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, the under floor side of the luggage floor portion of the vehicle.
The actuator unit 20 is, for example, for reducing the rotational force of a DC motor by a reduction gear train to rotate a lead screw, and pulling or relaxing the parking brake cable 21 by an equalizer screwed to the lead screw.

  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 is a Bowden cable that 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 traction force applied to the parking brake cable 21. The adjustment of the traction force is performed by controlling the power supply to the actuator unit 20 to change the stroke for pulling the parking brake cable 21. For this reason, the actuator unit 20 has a stroke sensor (not shown) that detects the traction stroke. It has.

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 each electrical component such as the controller 40 via wiring (harness). As shown in FIG. 1, the wiring for supplying power from the plus terminal 31 to the controller 40 is provided with an ignition wiring 31a and a constant connection wiring 31b. The ignition wiring 31a is inserted at its intermediate portion with an ignition relay I which is switched between conduction and interruption in conjunction with the on / off of the ignition switch, and is energized when the engine, which is the driving power source of the vehicle, is on (running). is there. The always-connected wiring 31b is always energized regardless of the operation of the ignition switch, and is used for holding various data in the ECU 41 of the controller 40 or the like.
The minus terminal 32 is grounded to the metal part of the vehicle body.

  The controller 40 is an electric parking brake control device that controls the actuator unit 20 and changes the traction force of the parking brake cable 21 to switch between the released state and the braking state of the parking brake 10 and changes the braking force. ECU 41, relay 42, G sensor 43, and actuator temperature sensor 44 are provided.

The ECU 41 determines whether or not the parking brake 10 needs to be braked in accordance with inputs from the operation switch 50 and the vehicle-side unit 60, and also performs a CPU that performs additional pulling control for increasing the braking force when the vehicle stops on an inclined road. I have.
Further, the ECU 41 has a function of detecting a current value of electric power supplied to the actuator unit 20 via the relay 42.
Further, the ECU 41 also functions as a set current value changing unit that changes a set current value, which is a threshold value of the current supplied to the actuator unit 20, based on the outputs of the outside air temperature sensor 62 and the actuator temperature sensor 44, as will be described later. To do.

  The relay 42 is a power supply unit that supplies driving power to the actuator unit 20 in accordance with a control signal output from the ECU 41, and the transition of the parking brake 10 from the braking state to the released state, and the released state. In order to make the transition from the braking state to the braking state, a function of reversing the polarity of the driving 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 G sensor 43 includes an acceleration sensor that detects an actual acceleration in the front-rear direction of the vehicle, and inputs the output to the ECU 41.

  The actuator temperature sensor 44 is disposed in the vicinity of the actuator unit 20, detects the ambient temperature of the environment where the actuator unit 20 is installed, and transmits it to the ECU 41.

  The operation switch 50 is an operation unit for a user such as a driver to input a manual selection operation of a braking state and a release state of the parking brake 10, an additional operation, and an auto mode selection operation. A push button switch mounted on an instrument panel (not shown) of the vehicle is provided. The operation switch 50 transmits the input to the controller 40, and the controller 40 supplies driving power to the actuator unit 20 in response to this to drive the parking brake 10.

  The vehicle unit 60 includes, for example, an engine control unit (ECU) that controls the engine of the vehicle, a transmission control unit (TCU) that controls a transmission (transmission), and a safety control that performs vehicle stability control including ABS control. The unit includes a vehicle integration unit that comprehensively controls other electrical components of the vehicle, and communicates with the controller 40 via a CAN communication system, which is a kind of in-vehicle LAN, and includes a vehicle speed sensor 61 and an outside air temperature sensor 62. It has.

  The vehicle speed sensor 61 is provided, for example, in a wheel hub portion, and is used for detecting a vehicle traveling speed (body speed) by outputting a vehicle speed pulse signal corresponding to the rotational speed of a tone wheel that rotates with the wheels. . Here, the vehicle speed sensor 61 generates a vehicle speed pulse signal corresponding to the vehicle speed at a speed equal to or higher than the detection lower limit speed.

  The outside air temperature sensor 62 detects the outside air temperature of the vehicle, and is used, for example, for control of an auto air conditioner.

The vehicle-side unit 60 sends, for example, engine speed, throttle opening, engine coolant temperature, exhaust temperature, transmission shift position, foot brake operation status (brake lamp switch signal), vehicle Information such as speed (vehicle speed) is provided sequentially. In the automatic operation mode, the controller 40 shifts the parking brake 10 from the braking state to the release state when it is determined that the vehicle shifts from the stopped state to the traveling state based on these inputs.
On the other hand, when the controller 40 determines that the vehicle has shifted from the traveling state to the stopped state (stop determination), the controller 40 determines that the parking brake 10 needs to be braked, and supplies driving power to the actuator unit 20 to supply the parking brake. 10 is shifted from the release state to the braking state.

  The warning lamp 70 is provided, for example, on an instrument panel of an instrument panel (not shown), and is turned on by a signal from the controller 40 in accordance with the operating state of the electric parking brake device or the occurrence of an error.

Next, the drive current control of the actuator in the electric parking brake device described above will be described.
FIG. 2 is a flowchart showing drive current control of the actuator. Hereinafter, the steps will be described step by step.
<Step S01: Outside temperature T1 judgment>
The ECU 41 compares the outside air temperature T1 of the vehicle detected by the outside air temperature sensor 62 with a predetermined set value A. When the outside air temperature T1 is not more than the set value A, the ECU 41 proceeds to step S02, and the outside air temperature T1 is greater than the set value A. If larger, the process proceeds to step S05.

<Step S02: External temperature T1-ambient temperature T2 determination>
The ECU 41 compares a value obtained by subtracting the ambient temperature T2 of the actuator detected by the actuator temperature sensor 44 from the outside air temperature T1 with a predetermined set value B, and when the outside air temperature T1−the ambient temperature T2 is equal to or lower than the set value B, The process proceeds to step S03 assuming that the predetermined low temperature condition is satisfied, and if the outside air temperature T1-atmosphere temperature T2 is higher than the set value B, the process returns to step S01 as the low temperature condition is not satisfied.

<Step S03: Setting current value variable mode>
When the actuator unit 20 is driven, the ECU 41 starts a set current value variable mode in which a set current value (current value control threshold) that is a threshold value for ending power supply is continuously varied based on the outside air temperature T1.
In the set current value variable mode, for example, control is performed to linearly increase the set current value as shown in the following equation 1 in accordance with a decrease in the outside air temperature T1.

Setting current value = −A × T1 + B (1)
However, A and B are predetermined constants.

When the actuator unit 20 is driven to shift the parking brake 10 from the released state to the braked state, the current value is monitored while the actuator unit 20 is energized from the relay 42, and the current value becomes the set current value. When the power reaches, the power supply is stopped, and the driving of the actuator unit 20 is finished.
Proceed to step S04.

<Step S04: Determination of outside temperature T1 and outside temperature T1 ambient temperature T2>
The ECU 41 compares the outside air temperature T1 with the set value A, compares the outside air temperature T1-atmosphere temperature T2 with the set value B, the outside air temperature T1 is larger than the set value A, and the outside air temperature T1-atmosphere temperature T2 is the set value. If it is larger than B, the process proceeds to step S04. In other cases, the process returns to step S01 to repeat the subsequent processes.

<Step S05: Set Current Value Constant Mode>
The ECU 41 sets the above-described set current value to a constant value regardless of the outside air temperature T1 and the ambient temperature T2, and ends the series of processes.

Hereinafter, the effect by the Example mentioned above is demonstrated.
FIG. 3 is a graph showing an example of the relationship between temperature and current in the actuator of the electric parking brake device.
In FIG. 3, when a predetermined low temperature condition is satisfied as in the embodiment, the set current value when the set current value is changed according to the temperature is indicated by a solid line, and the set current value set constant regardless of the temperature is indicated by a broken line. The current value necessary for generating a constant torque is shown by a one-dot chain line.

  As shown in FIG. 3, the current value required to generate a constant torque increases as the electrical characteristics change or the grease for lubrication hardens as the temperature decreases. For this reason, when the set current value is constant regardless of the temperature, for example, in a low temperature state of −10 ° C. or lower, the torque generated by the actuator when the set current value is energized decreases, and as a result, the parking brake is controlled. There is a risk that the vehicle will start to move due to insufficient power.

  On the other hand, as in this example, when a predetermined low temperature condition is satisfied, a change in electrical characteristics and hardening of the grease are noticeable by increasing the set current value according to a decrease in temperature. Even under a low temperature environment, a sufficient torque can be generated in the actuator to ensure a braking force and prevent the vehicle from starting due to a road surface inclination or the like.

(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) In the embodiment, the set current value is changed based on the outside air temperature and the actuator ambient temperature, but other parameters may be used as the parameters correlated with the actuator ambient temperature.
For example, when the actuator is disposed in the vehicle interior, the temperature in the vehicle interior may be used as the atmospheric temperature.
Further, when the actuator is disposed outside the passenger compartment and in the vicinity of the exhaust system, the ambient temperature may be calculated based on the outside air temperature and the exhaust temperature. For example, the difference between the outside air temperature and the exhaust temperature may be calculated as the ambient temperature.
Furthermore, when the actuator is arranged in the engine room, the ambient temperature may be calculated based on the outside air temperature and the engine coolant water temperature. For example, the difference between the outside air temperature and the water temperature may be calculated as the ambient temperature.
The reason for using the room temperature, exhaust temperature, water temperature, etc. in addition to the outside temperature in this way is that even if the outside temperature is low, the grease etc. is softened by the heat generated by the indoor air conditioning, engine, exhaust system, etc. It is because there is a case where it is.
(2) The configuration of the electric parking brake device is not limited to that of the embodiment, and can be changed as appropriate.
For example, the parking brake of the embodiment uses a drum arranged 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 or drum brake for brake and its friction material may be shared and integrated with the parking brake.
Further, the parking brake of the 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, the electric actuator is a wheel. The present invention can also be applied to a so-called built-in type electric parking brake provided on the hub side and integrated with the parking brake.

It is a block diagram which shows the structure of the Example of the electric parking brake apparatus containing the electric parking brake control apparatus to which this invention is applied. 3 is a flowchart showing drive current control of an actuator in the electric parking brake device of FIG. 1. It is a graph which shows an example of the relationship between the temperature and electric current value in the actuator of an electric parking brake device.

Explanation of symbols

10 Parking brake 20 Actuator unit 30 Parking brake cable 40 Controller 41 ECU
43 G sensor 44 Actuator temperature sensor 50 Operation switch 60 Vehicle side unit 61 Vehicle speed sensor 62 Outside air temperature sensor 70 Warning light

Claims (4)

In the electric parking brake control device that controls the electric actuator that drives the parking brake,
A power supply unit that supplies power to the electric actuator and stops supplying the power when a current passed through the electric actuator reaches a set current value;
An ambient temperature detector for detecting a parameter correlated with the ambient temperature in the electric actuator;
An electric parking brake control device comprising: a set current value changing unit that changes the set current value in the power supply unit based on an output of the ambient temperature detecting unit. In the electric parking brake control device according to claim 1,
The electric parking brake control device, wherein the set current value changing unit increases the set current value when a parameter correlated with the ambient temperature satisfies a predetermined low temperature condition. The electric parking brake control device according to claim 2,
The set current value changing unit sets the set current value based on the parameter correlated with the ambient temperature when the parameter correlated with the ambient temperature satisfies a predetermined low temperature condition. Brake control device. In the electric parking brake control device according to any one of claims 1 to 3,
The electric parking brake control device, wherein the parameter correlated with the ambient temperature is detected based on at least one of an outside air temperature, an indoor temperature, an engine exhaust temperature, and an engine cooling water temperature.

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