JP4449870B2 - Failure detection device for wheel speed sensor - Google Patents

Description

  The present invention relates to a failure detection device for a wheel speed sensor that detects a wheel speed of a drive wheel that is rotationally connected to a drive device of a vehicle.

Generally, the wheel speed is detected for estimating the vehicle body speed of the vehicle. Patent Document 1 includes wheel speed sensors 32FR to 32RR that detect wheel speeds of the left and right drive wheels 10FL and 10FR and driven wheels 10RL and 10RR as shown in FIGS. The detected wheel speed of each wheel is filtered (step 20), the reference value Vwc is set based on the maximum value of the wheel speeds of the four wheels after the filtering process (step 30), and the wheel speed sensors 32RL and 32RR are set. When the wheel speeds of the driven wheels 10RL and 10RR detected by the above exceed the reference value, the vehicle body speed is determined based on the maximum wheel speed of the wheel speeds of wheels other than the driven wheel whose wheel speed exceeds the reference value. The estimation is described.
JP 2000-108875 (pages 3 and 4, FIGS. 1 and 2)

  However, when the wheel speed detected by the wheel speed sensor of one driven wheel is larger than the reference value obtained based on the wheel speeds of all the filtered wheels, Since the wheel speed detected by the wheel speed sensor of the driven wheel is invalidated in the estimation of the vehicle body speed, it is determined whether the output value of the wheel speed sensor of the driven wheel is abnormal or not. A sensor failure cannot be detected.

  Further, as a wheel speed sensor failure detection device, the output value of the wheel speed sensor is compared with the output value of another wheel speed sensor, for example, the output value of the wheel speed sensor is continuously 0 for a predetermined determination time, If the output value of the other wheel speed sensor is not 0, the output value of the wheel speed sensor with an output value of 0 may be determined to be abnormal, but there is a risk of erroneous determination when the wheel is stuck or the like. is there. In order to prevent such erroneous determination, there is a problem that a sufficiently long determination time is required for output value abnormality determination, delay in failure detection cannot be avoided, and it is difficult to reliably prevent erroneous detection.

  The present invention relates to a wheel speed sensor failure detection device that shortens the wheel speed sensor failure detection time and prevents erroneous detection by determining the validity of the output value of the wheel speed sensor that detects the wheel speed of the drive wheel. Is to provide.

  In order to solve the above problems, the structural feature of the invention according to claim 1 is that the drive wheel (11) is based on the rotational speed of the drive device (12, 13) detected by the drive rotational speed sensor (20). The average wheel speed is obtained by averaging the wheel speeds detected by the estimated wheel speed calculating means (step S2) for calculating the estimated wheel speed and the wheel speed sensor (19) for detecting the wheel speed of the drive wheel (11). Average wheel speed calculating means (step S3) for calculating, and validity determining means for determining the validity of the output value of the wheel speed sensor (19) based on the estimated wheel speed and the average wheel speed (step S4). S5), an abnormality determining means (step S8) for determining that the wheel speed sensor is abnormal when the output value of the wheel speed sensor is in an abnormal state for an abnormality determination time, and the presence When the sex determination means determines that the output value of the wheel speed sensor is low, the abnormality determination time setting means (step S6) sets the abnormality determination time to a shorter time than when it is determined that the effectiveness is high. , S7).

  The structural feature of the invention according to claim 2 is that, in claim 1, the drive device is an engine (12), and the rotation of the engine is changed at a transmission ratio by the transmission mechanism (23) and the drive wheel is rotated. (11), the drive rotational speed sensor (20) detects the rotational speed of the engine, and the estimated wheel speed calculation means (step S2) is based on the rotational speed of the engine and the transmission ratio. It is to calculate the estimated wheel speed of the drive wheel.

  The structural feature of the invention according to claim 3 is that, in claim 1, the drive device is an engine (12) and a torque converter (13) driven by the engine, and the rotation of the output shaft of the torque converter is The transmission mechanism (23) changes the transmission ratio and transmits it to the drive wheel (11). The drive rotation speed sensor (20) detects the rotation speed of the output shaft of the torque converter and calculates the estimated wheel speed. The means (step S2) is to calculate an estimated wheel speed of the drive wheel based on the rotation speed of the output shaft of the torque converter and the transmission ratio.

  According to a fourth aspect of the present invention, the drive device is an electric motor according to the first aspect, and the rotation of the electric motor is changed by a transmission ratio by the transmission mechanism (23) and the drive wheel ( 11), the drive rotation speed sensor (20) detects the rotation speed of the electric motor, and the estimated wheel speed calculation means (step S2) is based on the rotation speed of the electric motor and the transmission ratio. And calculating an estimated wheel speed of the drive wheel.

  The structural feature of the invention according to claim 5 is that, in claim 2, the speed change mechanism (23) includes a manual transmission (14), and the manual transmission is effective when the manual transmission is in a neutral position. The determination of the validity of the output value of the wheel speed sensor (19) by the sex determination means (steps S4, S5) is not performed.

  According to a sixth aspect of the present invention, in the second aspect, the speed change mechanism (23) includes a manual transmission (14) connected to or disconnected from the engine (12) by a clutch (13). When the clutch is disengaged or engaged by a half-clutch, the validity determination means (steps S4 and S5) does not determine the validity of the output value of the wheel speed sensor (19).

   According to the invention according to claim 1 configured as described above, the estimated wheel speed of the drive wheel (11) is calculated based on the rotational speed of the drive device (12, 13) and detected by the wheel speed sensor (19). The average wheel speed is calculated by averaging the wheel speeds of the driven wheels, the validity of the output value of the wheel speed sensor is determined based on the estimated wheel speed and the average wheel speed, and the output value of the wheel speed sensor is valid. If it is determined that the abnormality is low, the abnormality determination means sets the abnormality determination time for determining that the output value of the wheel speed sensor is abnormal to be shorter than when determining that the effectiveness is high, so the abnormality determination time is shortened. In addition, it is possible to prevent erroneous determination.

  According to the invention according to claim 2 configured as described above, the drive wheel is based on the rotational speed of the engine (12) and the transmission ratio of the transmission mechanism (23) that transmits the rotation of the engine to the drive wheel (11). Therefore, the effectiveness of the output value of the wheel speed sensor is determined based on the estimated wheel speed and the average wheel speed of the driving wheel. Can be determined.

  According to the invention of claim 3 configured as described above, the speed change mechanism (23) that transmits the rotational speed of the torque converter (13) driven by the engine (12) and the rotation of the torque converter to the drive wheels (11). ) To calculate the estimated wheel speed of the drive wheel based on the transmission ratio and determine the effectiveness of the output value of the wheel speed sensor based on the estimated wheel speed and the average wheel speed of the drive wheel. Therefore, the effectiveness of the output value of the wheel speed sensor can be determined with a simple configuration in the vehicle.

  According to the fourth aspect of the invention configured as described above, the estimation of the drive wheel is based on the rotation speed of the electric motor and the transmission ratio of the speed change mechanism (23) that transmits the rotation of the electric motor to the drive wheel (11). Since the wheel speed is calculated and the validity of the output value of the wheel speed sensor is determined based on the estimated wheel speed and the average wheel speed of the driving wheel, the wheel speed sensor can be configured with a simple configuration in a vehicle driven by an electric motor. The validity of the output value can be determined.

  According to the invention according to claim 5 configured as described above, when the manual transmission (14) is put in neutral, the validity of the output value of the wheel speed sensor (19) is not determined. In a vehicle equipped with a manual transmission, a wheel speed sensor failure can be detected while preventing erroneous determination.

  According to the invention according to claim 6 configured as described above, when the clutch (13) is disengaged or connected by a half-clutch, the validity of the output value of the wheel speed sensor (19) is not determined. In the vehicle (10) that transmits the rotation of the engine (12) to the drive wheels (11) through the clutch, it is possible to detect a failure of the wheel speed sensor in a short time while preventing erroneous determination.

   DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a wheel speed sensor failure detection apparatus according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the four-wheel drive vehicle 10 is configured such that the driving force of the engine 12 is optimally distributed to the left and right front wheels 11fl and 11fr and the left and right rear wheels 11rl and 11rr according to the traveling state. The components provided in relation to the front, rear, left, and right drive wheels 11 have the same configuration and operation, and therefore, reference numerals obtained by adding the same arithmetic numerals to the corresponding arithmetic components with Roman letters f and r, respectively. The front and rear are distinguished, and the left and right letters are distinguished by adding l and r. It should be noted that in the specification, when components are shown without distinction between front, back, left, and right, only the corresponding arithmetic numbers are given as reference numbers.

   The engine 12 is rotationally connected to the pump impeller of the torque converter 13, and the output shaft connected to the turbine of the torque converter 13 is connected to the input shaft of the automatic transmission 14. An output shaft of the automatic transmission 14 is connected to a front differential 16f and a rear differential 16r via a center differential 15 by a front output shaft 17f and a rear output shaft 17r. The front differential 16f and the rear differential 16r are rotationally coupled to the left and right front wheels 11fl and 11fr and the left and right rear wheels 11rl and 11rr via drive shafts 18f and 18r.

  Each driving wheel 11 is provided with a wheel speed sensor 19 to detect the wheel speed Nr of the driving wheel 11. A drive rotational speed sensor 20 that detects the rotational speed of the output shaft of the torque converter 13 is provided for the output shaft of the torque converter 13. A wheel speed sensor 19, a drive rotation speed sensor 20, and an automatic transmission ECU 22 are connected to the failure detection ECU 21.

  Transmission to the failure detection ECU 21 is a transmission mechanism 23 that transmits the rotation speed No of the output shaft of the torque converter 13 detected by the drive rotation speed sensor 20 and the rotation speed No of the output shaft of the torque converter 13 to each drive wheel 11. The estimated wheel speed Ns of the drive wheel 11 is calculated based on the ratio k, the average wheel speed Na is calculated by averaging the wheel speed Nr of all the drive wheels 11 detected by the wheel speed sensor 19, and the estimated wheel speed Ns. When the validity of the output value of the wheel speed sensor 19 is determined based on the average wheel speed Na and it is determined that the effectiveness of the output value of the wheel speed sensor is low, the abnormality determination means determines the output value of the wheel speed sensor. The abnormality determination time for determining an abnormality is set to a shorter time than when it is determined that the effectiveness is high, and the abnormality determination means determines whether or not the output value of the wheel speed sensor 19 is abnormal. Disabled detection program is stored.

  The automatic transmission ECU 22 selectively connects a control clutch and a control brake of the automatic transmission 14 to establish a gear stage suitable for the traveling state of the vehicle 10. The transmission mechanism 23 includes an automatic transmission 14, a center differential 15, and front or rear differentials 16f and 16r. The transmission ratio k is a shift of the currently established shift stage of the automatic transmission 14 input from the automatic transmission ECU 22. The ratio is multiplied by the gear ratio of the center differential 15 and the gear ratio of the front or rear differentials 16f and 16r. The failure detection ECU 21 and the automatic transmission ECU 22 are mainly composed of a microcomputer having a CPU, a ROM, a RAM, an input / output unit, and the like.

   Next, the operation of the above embodiment will be described. When the failure detection program shown in FIG. 2 is started, the failure detection ECU 21 determines the wheel speed Nr of each drive wheel 11 and the rotation speed No of the output shaft of the torque converter 13 from each wheel speed sensor 19 and the drive rotation speed sensor 20. The automatic transmission ECU 22 receives the currently established gear position of the automatic transmission 14 (step S1). The rotational speed No of the output shaft of the torque converter 13 is multiplied by the gear ratio of the shift stage of the automatic transmission 14, the gear ratio of the center differential 15, and the gear ratio of the front or rear differentials 16 f and 16 r, and the estimated wheel speed of the drive wheels 11. Ns is calculated (step S2). The average value of the wheel speeds Nr of the drive wheels 11 detected by the wheel speed sensors 19 is calculated as the average wheel speed Na (step S3).

   When the ratio Na / Ns between the average wheel speed Na and the estimated wheel speed Ns is calculated and the ratio Na / Ns is between the first and second constants, the driving wheel 11 detected by each wheel speed sensor 19 is detected. It is determined that the wheel speed Nr is highly effective (step S4). When the vehicle 10 is traveling straight and the output shaft connected to the turbine of the torque converter 13 is connected to each drive wheel 11, the ratio Na / Ns is theoretically 1. While driving on a flat road with more driving force allocated to the front wheels 11f than the rear wheels 11r, the front wheels 11f have a higher slip rate than the rear wheels 11r, and slip occurs on the rear output shaft side of the center differential 15. In the case of occurrence, the ratio Na / Ns is smaller than 1. Further, by slipping on the rear output shaft side of the center differential 15, the rear wheel 11 r passes through the convex portion of the road surface while traveling in a state where the distribution of driving force to the front wheel 11 f and the rear wheel 11 r can be changed. Thus, the ratio Na / Ns is greater than 1 when the rotational speed is increased from the front wheel 11f. In consideration of such various traveling conditions, when the ratio Na / Ns is between the first and second constants, which are two values around 1, the effectiveness of the output value of the wheel speed sensor 19 is high. It is considered that the possibility that the wheel speed sensor 19 is broken is low.

   When the ratio Na / Ns is between the first and second constants and the validity determination means determines that the output value of the wheel speed sensor is high (steps S4 and S5), the abnormality determination means determines the wheel speed. An abnormality determination time T for determining that the output value of the sensor 19 is abnormal is set to a predetermined time T2 (step S6), and it is determined whether or not the output value of the wheel speed sensor 19 is abnormal (step S8). When the output value of the wheel speed sensor 19 continues to be in the abnormal state for the abnormality determination time T, in step S8 as abnormality determination means for determining that the wheel speed sensor 19 is abnormal, the wheel speed sensor 19 of the drive wheel 11 is detected. The output value is compared with the output value of the wheel speed sensor 19 of the other driving wheel 11. For example, the output value of the wheel speed sensor 19 is 0 continuously for the abnormality determination time T, and the output value of the other wheel speed sensor 19 is Is not 0, it is determined that the output value of the wheel speed sensor 19 whose output value is 0 is abnormal, and a failure of the wheel speed sensor 19 is detected. When the output value of the wheel speed sensor 19 is low, the abnormality determination time T when the abnormality determination means determines that the output value of the wheel speed sensor 19 is abnormal is shorter than T1 when it is determined that the output value is high. It is set (step S7), and it is determined whether or not the output value of the wheel speed sensor 19 is abnormal (step S8).

   As described above, when it is determined that the output value of the wheel speed sensor 19 is high, the abnormality determination time T is set to the predetermined time T2, and the abnormality determination means determines the abnormality of the output value of the wheel speed sensor. Incorrect determination due to wheel stacks or the like can be prevented. When it is determined that the time is lower, the abnormality determination time T is set to a shorter time T1 than the predetermined time T2, and the abnormality determination means determines an abnormality in the output value of the wheel speed sensor. Can respond quickly.

   In the above embodiment, the engine 12 is connected to the automatic transmission 14 via the torque converter 13, but when the torque converter 13 is the clutch 13 and the automatic transmission 14 is the manual transmission 14 in FIG. The engine 12 is connected to or disconnected from the manual transmission 14 by a clutch 13 and is connected to the drive wheels 11 via the manual transmission 14. In this case, the drive rotational speed sensor 20 detects the rotational speed No of the engine 12. When the manual transmission 14 is in the neutral position or when the clutch 13 is disengaged or engaged with a half-clutch, the estimated rotational speed Ns is independent of the drive rotational speed No, and the wheel speed sensor 19 is effective. It becomes impossible to make sex determination. However, by providing a detecting means for detecting the clutch disengagement or half-clutch, when the detecting means has not detected the clutch disengagement or half-clutch, it is possible to apply the wheel speed sensor failure detection device described above. it can. In this case, the transmission mechanism 23 includes the manual transmission 14, the center differential 15, and the front or rear differentials 16f and 16r.

   When the driving wheel 11 is rotationally driven by the electric motor via the center differential 15 and the front or rear differentials 16f and 16r, the driving rotational speed sensor (20) detects the rotational speed (No) of the electric motor. To. In this case, the transmission mechanism 23 includes a center differential 15 and front or rear differentials 16f and 16r.

The figure which shows embodiment of the failure detection apparatus of the wheel speed sensor which concerns on this invention. The figure which shows a failure detection program.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Four-wheel drive vehicle, 11 ... Drive wheel, 12 ... Engine, 13 ... Torque converter or clutch, 14 ... Automatic transmission or manual transmission, 15 ... Center differential, 16f, 16r ... Front and rear differential, 19 ... Wheel Speed sensor 20... Drive rotation speed sensor 21. Failure detection ECU 22. Automatic transmission ECU 23.

Claims (6)

Estimated wheel speed calculation means (step S2) for calculating an estimated wheel speed of the drive wheel (11) based on the rotation speed of the drive device (12, 13) detected by the drive rotation speed sensor (20);
Average wheel speed calculating means (step S3) for calculating the average wheel speed by averaging the wheel speed detected by the wheel speed sensor (19) for detecting the wheel speed of the drive wheel (11);
Validity determination means (steps S4 and S5) for determining the validity of the output value of the wheel speed sensor (19) based on the estimated wheel speed and the average wheel speed;
An abnormality determining means (step S8) for determining that the wheel speed sensor is abnormal when the output value of the wheel speed sensor is in an abnormal state continuously for an abnormality determination time;
When the effectiveness determination means determines that the output value of the wheel speed sensor is low, an abnormality determination time setting means that sets the abnormality determination time in a shorter time than when it is determined that the effectiveness is high ( Steps S6 and S7)
A failure detection apparatus for a wheel speed sensor, comprising: 2. The drive device according to claim 1, wherein the drive device is an engine (12), and the rotation of the engine is changed by a transmission ratio by the transmission mechanism (23) and transmitted to the drive wheel (11). 20) detects the rotational speed of the engine, and the estimated wheel speed calculating means (step S2) calculates the estimated wheel speed of the drive wheel based on the rotational speed of the engine and the transmission ratio. Fault detection device for wheel speed sensor. 2. The drive device according to claim 1, wherein the drive device is an engine (12) and a torque converter (13) driven by the engine, and the rotation of the output shaft of the torque converter is changed at a transmission ratio by the transmission mechanism (23). The drive wheel (11) is transmitted, the drive rotation speed sensor (20) detects the rotation speed of the output shaft of the torque converter, and the estimated wheel speed calculation means (step S2) is the output shaft of the torque converter. A failure detection apparatus for a wheel speed sensor, which calculates an estimated wheel speed of the drive wheel based on a rotation speed of the vehicle and the transmission ratio. The drive device according to claim 1, wherein the drive device is an electric motor, and the rotation of the electric motor is shifted by the transmission mechanism (23) at a transmission ratio and transmitted to the drive wheel (11), and the drive rotation speed sensor (20). ) Detects the rotational speed of the electric motor, and the estimated wheel speed calculating means (step S2) calculates the estimated wheel speed of the drive wheel based on the rotational speed of the electric motor and the transmission ratio. A failure detection device for a wheel speed sensor. 3. The wheel speed according to claim 2, wherein the speed change mechanism (23) includes a manual transmission (14), and when the manual transmission is in a neutral position, the wheel speed by the effectiveness determination means (steps S4 and S5). A failure detection device for a wheel speed sensor, wherein the validity of the output value of the sensor (19) is not determined. 3. The transmission (23) according to claim 2, wherein the transmission mechanism (23) includes a manual transmission (14) that is connected to or disconnected from the engine (12) by a clutch (13), and the clutch is connected by disconnection or half-clutch. The wheel speed sensor failure detection apparatus is characterized in that the validity determination means (steps S4 and S5) does not determine the validity of the output value of the wheel speed sensor (19).

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