Electronic 4WD system having reinforced ABS cooperative control performance and method of controlling same

Abstract

The present invention relates to an electronic 4WD system having reinforced ABS cooperative control performance, in which an ABS ACT signal by an ABS (Anti-Lock Brake System) controller and a 4WD_OPEN signal by the ESC (Electronic Stability Control) controller are used. When the ABS ACT signal and the 4WD_OPEN signal are recognized, it is determined that it is an ESC vehicle and a 4WD mode is stopped. When only the ABS ACT signal is recognized, it is determined that it is an ABS vehicle and the intention of a user is determined on the basis of whether a brake pedal has been pressed down or an accelerator pedal has been released, and then a 4WD mode is stopped.

Claims

1. A method of controlling an electronic 4WD system having reinforced Anti-Lock Brake System (ABS) cooperative control performance, the method comprising: (A) recognizing, by an electronic 4WD system, an ABS ACT signal by an ABS controller and a 4WD_OPEN signal by an ESC (Electronic Stability Control) controller; (B) determining that a driver intends to brake a vehicle and stopping a 4WD mode, when the ABS ACT signal and the 4WD_OPEN signal are both recognized; (C) determining whether the vehicle is braked by intention of the driver on the basis of a brake pedal signal, when only the ABS ACT signal is recognized; and (D) stopping the 4WD mode upon determination that the vehicle is braked by intention of the driver when the brake pedal signal is transmitted, or maintaining the 4WD mode upon determination that the vehicle is braked regardless of intention of the driver, when the brake pedal signal is not transmitted.

2. The method of claim 1, wherein the determining whether the vehicle is braked by intention of the driver further uses a signal showing release of an accelerator pedal.

3. The method of claim 2, wherein the signal showing release of the accelerator pedal is an OFF-signal.

4. An electronic 4WD system having reinforced Anti-Lock Brake System (ABS) cooperative control performance, wherein an ABS controller and an Electronic Stability Control (ESC) controller are connected by CAN communication, and the system includes an ABS sub-logic that determines that it is an ESC vehicle and stops a 4WD mode when an ABS ACT signal by the ABS controller and a 4WD_OPEN signal by the ESC controller are both recognized, and determines that it is an ABS SOLO vehicle when only the ABS ACT signal is recognized, and stops the 4WD mode only when a signal indicating that a brake pedal has been pressed down or a signal indicating that an accelerator pedal has been released is detected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A and 1B are flowcharts illustrating a method of controlling an electronic 4WD system having reinforced ABS cooperative control performance according to an embodiment of the present invention.

(2) FIG. 2 is an output diagram of an electronic 4WD system having reinforced ABS cooperative control performance according to an embodiment of the present invention.

(3) FIG. 3 is an exemplary configuration of an electronic 4WD system having reinforced ABS cooperative control performance according to an embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

(4) FIGS. 1A and 1B are flowcharts illustrating a method of controlling an electronic 4WD system having reinforced ABS cooperative control performance according to an embodiment of the present invention. FIG. 2 is a diagram showing an exemplary configuration of an electronic 4WD system controlled by the method shown in FIGS. 1A and 1B. Accordingly, control to be described hereafter is implemented through an electronic 4WD system 10.

(5) Reference numeral S10 indicates a step in which ABS ACT and 4WD_OPEN signals are input to the electronic 4WD system 10, in which the ABS ACT signal is generated by an ABS (Anti-Lock Brake System) controller 200 and the 4WD_OPEN signal is generated by an ESC (Electronic Stability Control) controller 100.

(6) In detail, the ABS controller 200 uses the ABS ACT signal as a stop signal requested by a 4WD ECU. Because a logic for removing the side effect of a 4WD control logic cannot be loaded on the ABS controller 200 in an ABS vehicle, there is no 4WD OPEN signal. In contrast, the ESC controller 100 uses the 4WD_OPEN signal as a stop signal requested by a 4WD ECU, because whether a driver operates a brake pedal is determined by checking the pressure of a master cylinder in a brake when an ABS ACT signal is activated. That is, as shown FIG. 2, the logic loaded on the ESC controller 100 to remove the side effect of a 4WD control logic determines whether the pressure of the master cylinder of a brake is over a reference pressure due to activation of an ABS _ACT signal, and then a request for stopping a 4WD mode is made.

(7) The ABS_ACT and the 4WD_OPEN are output as CAN SIGNALs.

(8) Reference numeral S20 indicates a step of determining whether an ABS_ACT and a 4WD_OPEN are both recognized by the electronic 4WD system 10.

(9) When the electronic 4WD system 10 recognizes both of the ABS_ACT and the 4WD_OPEN in Step (S20), the electronic 4WD system 10 determines that it is an ESC vehicle and enters Step (S30), thereby performing cooperative control for stopping a 4WD mode according to activation of an 4WD OPEN signal.

(10) In contrast, when the electronic 4WD system 10 recognizes only the ABS_ACT in Step (S20), the electronic 4WD system 10 determines that it is an ABS SOLO vehicle and enters a step, such as Step (S40), for removing the side effect of a 4WD control logic.

(11) In detail, the intention of braking by a driver is determined in Step (S40), and to this end, the electronic 4WD system 10 determines whether the brake pedal has been pressed down in response to a signal from a brake pedal sensor or whether the accelerator pedal has been released in response to a signal from an accelerator pedal sensor.

(12) When the electronic 4WD system 10 recognizes that the brake pedal has been pressed down and the accelerator pedal has been released in Step (S40), the system directly enters Step (S50), thereby performs cooperative control for stopping the 4WD mode in accordance with the intention of braking by the driver. On the contrary, when the electronic 4WD system 10 does not recognize that the brake pedal has been pressed down or the accelerator pedal has been released in Step (S40), the system directly enters Step (S60), determines that activation of ABS_ACT is caused by the difference in speed of left and right wheels without a brake operation on a low-friction road (snowy road or icy road), and keeps the 4WD mode.

(13) The control results of Step (S20), Step (S40), and Step (S60) are exemplified in FIG. 3. As shown in the figure, ABS_ACT is activated at a specific time (B), but 4WD control torque is maintained at the time, so the side effect of a 4WD control logic that deteriorates driving ability or turns off the electronic 4WD system is removed.

(14) In the electronic 4WD system having reinforced ABS cooperative control performance according to the embodiment, the ABS ACT signal by the ABS (Anti-Lock Brake System) controller 200 and the 4WD_OPEN signal by the ESC (Electronic Stability Control) controller 100 are used, and when the ABS ACT signal and the 4WD_OPEN signal are recognized, it is determined that it is an ESC vehicle and a 4WD mode is stopped, but when only the ABS ACT signal is recognized, it is determined that it is an ABS vehicle and the intention of a user is determined on the basis of whether a brake pedal has been pressed down or an accelerator pedal has been released, and then a 4WD mode is stopped. Accordingly, the side effect of a 4WD control logic on a low-friction road (snowy road or icy road) with ABS ACT activated without a brake pedal operation is removed. In particular, the limit of loading a logic on the ABS controller 200 is removed by a sub-logic of the electronic 4WD system, so the driving ability of ABS SOLO 4WD is not deteriorated and the electronic 4WD system is not turned off.

(15) The foregoing exemplary embodiments are only examples to allow a person having ordinary skill in the art to which the present invention pertains (hereinafter, referred to as those skilled in the art) to easily practice the present invention. Accordingly, the present invention is not limited to the foregoing exemplary embodiments and the accompanying drawings, and therefore, a scope of the present invention is not limited to the foregoing exemplary embodiments. Accordingly, it will be apparent to those skilled in the art that substitutions, modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims and can also belong to the scope of the present invention.