KR20070070845A - Method of fail detection of wheel speed sensor - Google Patents

Abstract

A method for detecting the failure of a wheel speed sensor is provided to determine a failure state of the wheel speed sensor based on pulse state information of the wheel speed sensor and allow a driver to recognize the failure. It is determined whether or not a vehicle is rapidly accelerated, or braked based on the speed change of the vehicle in order to detect the failure of a wheel speed sensor to generate a pulse signal having a pulse width inversely proportional to a rotation speed of a gear rotating with a wheel(S306,S308). It is determined that impurities are inserted into the gear if the vehicle is not rapidly accelerated or braked, and high-speed duration is detected during one revolution period of the wheel(S314).

Description

Fault detection method of wheel speed sensor {METHOD OF FAIL DETECTION OF WHEEL SPEED SENSOR}

1 is a block diagram showing a control system of an anti-lock brake system of a vehicle according to an embodiment of the present invention.

2 is a view showing the structure of a wheel speed sensor applied to an embodiment of the present invention.

3 is a flowchart illustrating a failure detection method of a wheel speed sensor according to an exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

S1-S4: Wheel Speed Sensor

13: central computing unit

30: warning light

41: pole peace

42: coil

43: Permanent Magnet

44: signal leader

50: rotor

51: gear

52: damaged gear

53: foreign matter

Δt: air gap

The present invention relates to a failure detection method of a wheel speed sensor, and more particularly, to a failure detection method of a wheel speed sensor for detecting a failure of a wheel speed sensor while driving and informing a driver thereof.

Hyundai is increasing the number of vehicles equipped with an anti-lock brake system (ABS) to secure strong and stable brake performance as automobiles become more powerful. The ABS detects the wheel speed from the wheel speed sensor, calculates the slip ratio, and then controls the driving wheels so that the calculated slip ratio becomes the slip ratio in the control region. Therefore, the accuracy of the wheel speed sensor is required for ABS to perform this function. For this reason, it is most important that the vehicle control system and the driver can recognize and take action by detecting an early warning when a failure occurs in the wheel speed sensor.

An object of the present invention is to detect the failure of the wheel speed sensor through the pulse state information of the wheel speed sensor, and to notify the vehicle control unit and the driver when the failure occurs, so that it can recognize the failure of the wheel speed sensor. .

The failure detection method of the wheel speed sensor according to the present invention for this purpose is a failure detection method of the wheel speed sensor having a gear that rotates with the wheel and generates a pulse signal having a pulse width inversely proportional to the rotation speed of the gear. The method may include checking whether the vehicle is in a rapid acceleration and braking state by changing a speed of the vehicle; If a periodic high-speed section is detected during one revolution of the wheel when the vehicle is not in a rapid acceleration and braking state, it is determined that foreign matter has entered the gear of the wheel speed sensor.

Another failure detection method of the wheel speed sensor according to the present invention for the above-described object is a failure detection of the wheel speed sensor having a gear that rotates with the wheel and generates a pulse signal having a pulse width inversely proportional to the rotation speed of the gear A method comprising: checking whether a vehicle is in a rapid acceleration and braking state through a change in speed of the vehicle; If the periodic low speed section is detected during one revolution of the wheel when the vehicle is not in a rapid acceleration and braking state, it is determined that the teeth of the gear are broken.

Another failure detection method of the wheel speed sensor according to the present invention for the above-described object is a failure detection of the wheel speed sensor having a gear that rotates with the wheel and generates a pulse signal having a pulse width inversely proportional to the rotation speed of the gear A method comprising: checking whether a pulse width of a pulse signal changes continuously; If an intermittent high frequency pulse section is detected during one revolution of the wheel while the vehicle is braking, it is determined that an abnormal wheel speed due to vibration of the wheel is detected.

In addition, if it is determined that an abnormal wheel speed is detected, the vehicle control using the wheel speed detected through the wheel speed sensor is limited.

When described with reference to Figures 1 to 3 a preferred embodiment of the present invention made as described above. 1 is a block diagram illustrating a control system of an antilock brake system of a vehicle according to an exemplary embodiment of the present invention. As shown in FIG. 1, an antilock brake system according to an exemplary embodiment of the present invention includes a wheel speed sensor S1-S4, an electronic control unit ECU, and an antilock brake hydraulic circuit. The electronic control unit ECU stores the interface circuit 11, the pulse processing circuit 12, the central processing unit 13, the solenoid driving circuit 14, the motor relay driving circuit 15, and the relay driving circuit 16 such as a warning. Include.

The AC voltage signal, which is the output signal of the wheel speed sensors S1-S4, is converted into a pulse in the interface circuit 11, which counts and calculates the pulse in the pulse processing circuit 12.

In addition, the central computing device 13 calculates, analyzes and determines the numerical value calculated by the pulse processing circuit 12 according to a pre-programmed program, and based on the result, the solenoid driving circuit 14 and the motor relay driving circuit 15. Command to the relay drive circuit 15, such as a warning, to drive a normally open valve NO, a normal close valve NC, a motor relay MR, a warning relay WR, etc. do.

Further, the central computing unit 13 detects a failure of the wheel speed sensors S1-S4 through the state information of the pulse signal generated from the wheel speed sensors S1-S4, and drives a relay such as a warning based on the result. The circuit 16 is instructed to light the warning lamp 30.

The anti-lock brake hydraulic circuit includes a normal open valve NO and a normal close valve NC for adjusting the brake hydraulic pressure supplied from the master cylinder 21 to the wheel cylinder W, and the inlet side of the wheel cylinder W. It is arranged on the outlet side and prevents the wheels from being locked by performing the opening and closing operation by the command of the central computing device 13 during the braking operation. Reference numeral 22 is a motor, 23 is a pump, LPA is a low pressure accumulator, and HPA is a high pressure accumulator.

2 is a view showing the structure of a wheel speed sensor applied to an embodiment of the present invention. As shown in FIG. 2, the wheel speed sensors S1-S4 are arranged on the wheels so as to be spaced apart from the pole pieces 41, which are magnetic bodies, by a predetermined distance (?? t) from the pole pieces 41. It consists of a rotor (50) mounted and rotated. Reference numeral 42 denotes a coil, 43 a permanent magnet, and 44 a signal leader.

The rotor 50 has a number of tooth-shaped teeth 51 formed on the outer circumferential surface thereof, and when the gear 51 rotates, a magnetic field change occurs in the pole piece 41 so that an AC signal is output. The pulse signal is produced and provided to the central computing device 13. The pulse width of this pulse signal is inversely proportional to the wheel speed. As the wheel speed increases, the pulse width decreases, and conversely, as the wheel speed decreases, the pulse width increases. The pole piece 41 and the tooth 51 are assembled to have an air gap of about 0.3 mm to 1 mm, and the air gap is changed by some force applied from the outside or the sensing of the pole piece 41 is performed. If the angle is distorted, the wheel speed may not be detected while driving.

In addition, when there is a broken tooth 52 on the outer circumferential surface of the rotor 50, there is a case where the alternating magnetic field with the pole piece 41 is not generated and an AC signal is not output at the broken part so that the correct wheel speed is not detected. Occurs.

In addition, when the foreign matter 53 is attached between the tooth and the tooth of the tooth 51, the AC signal of the correct period does not occur, and thus the pulse width of the pulse signal may change large or small, so that the correct wheel speed May become impossible to detect.

Accordingly, the central computing device 13 continuously diagnoses the failure by detecting the operation state of the wheel speed sensors S1-S4 at regular intervals.

3 is a flowchart illustrating a failure detection method of a wheel speed sensor according to an exemplary embodiment of the present invention. As shown in FIG. 3, the central computing unit 13 first receives and stores state information of a pulse generated according to a detected value of the wheel speed sensors S1-S4 (302). This is to detect whether or not the wheel speed sensors S1-S4 have failed. When the state information of the pulse is obtained, the pulse width for the last one revolution of each wheel is calculated and stored (304).

Then, it is detected whether the speed change amount of the vehicle is below a certain size, which is to determine whether the vehicle is in a rapid acceleration state or a braking state. If the vehicle is not in a rapid acceleration state (NO in 306), then it is checked if the vehicle is in a braking state (308). At this time, if the vehicle is not in the braking state (NO in 308), it is determined that the vehicle is in a relatively constant driving state, not a rapid acceleration or braking state, and during one revolution of the wheel generated from the wheel speed sensors S1-S4. It is detected 312 whether the periodic low speed section exists and the periodic high speed section exists in the pulse signal (312). If the periodic low speed section is detected at 310 instead of the periodic low speed section at 310, it is determined that foreign matter is interposed between the teeth and the teeth of the tooth 51. This is because the low speed section occurs periodically even though it is a relatively constant speed driving state rather than a rapid acceleration or braking state because it can be interpreted that foreign matter intervenes between the teeth and the teeth of the gear 51 and abnormally affects the pulse width. to be.

Further, in step 316 of checking whether the vehicle is in the braking state, if the vehicle is in the braking state (YES in 308), the continuity of the pulse width change is checked (316). That is, if the vehicle is braking, the speed of the vehicle will gradually decrease, and in this case, since the pulse width will gradually increase, the detection of the continuity (ie, gradual increase) of the pulse width change causes the wheel speed sensor (S1-S4). Can determine whether there is a failure. If intermittent high frequency pulses (short cycle pulse signals with very small pulse widths) are detected in the pulse state information detected during one revolution of the wheel (YES in 318), this is abnormal due to vibration of the wheel during braking. It is determined that the wheel speed detection value is obtained, and the vehicle control using the wheel speed detection value is restricted to promote safe driving (320).

In addition, if the periodic low speed section is detected in step 312 (YES in 312), it is determined that some of the teeth of the tooth 51 are damaged (322).

The present invention detects the failure of the wheel speed sensor through the pulse state information of the wheel speed sensor, and when the failure occurs to notify the vehicle control unit and the driver to recognize the failure of the wheel speed sensor to ensure safe driving of the vehicle Make it possible.

Claims (4)

A failure detection method of a wheel speed sensor having a gear that rotates with a wheel and generating a pulse signal having a pulse width inversely proportional to the rotation speed of the gear, Determining whether the vehicle is in a rapid acceleration and braking state by changing the speed of the vehicle; And detecting a foreign matter in the gear of the wheel speed sensor when a periodic high-speed section is detected during one revolution of the wheel when the vehicle is not in a rapid acceleration and braking state. A failure detection method of a wheel speed sensor having a gear that rotates with a wheel and generating a pulse signal having a pulse width inversely proportional to the rotation speed of the gear, Determining whether the vehicle is in a rapid acceleration and braking state by changing the speed of the vehicle; And determining that the teeth of the gear are broken when a periodic low-speed section is detected during one revolution of the wheel when the vehicle is not in a rapid acceleration and braking state. In the failure detection method of the wheel speed sensor having a gear that rotates with the wheel and generates a pulse signal having a pulse width inversely proportional to the rotation speed of the gear, Confirming that the pulse width of the pulse signal continuously changes; And detecting an abnormal wheel speed according to vibration of the wheel when an intermittent high frequency pulse section is detected during one revolution of the wheel while the vehicle is braking. The method of claim 3, wherein If it is determined that the abnormal wheel speed is detected, the failure detection method of the wheel speed sensor for limiting the vehicle control using the wheel speed detected through the wheel speed sensor.

Images