Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/88—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
  • B60T8/885—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means using electrical circuitry
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P21/00—Testing or calibrating of apparatus or devices covered by the preceding groups
  • G01P21/02—Testing or calibrating of apparatus or devices covered by the preceding groups of speedometers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T2270/00—Further aspects of brake control systems not otherwise provided for
  • B60T2270/40—Failsafe aspects of brake control systems
  • B60T2270/416—Wheel speed sensor failure

Definitions

• the invention relates to a method for monitoring wheel speeds, comprising the steps of: determining wheel speeds, determining "of the wheel having the maximum wheel velocity, determining the wheel having the minimum wheel speed, determining the differential speed between the maximum wheel speed and the minimum wheel speed and comparing the Differential speed with a threshold.
• the invention further relates to a device for monitoring wheel speeds with means for determining the wheel speeds. Means for determining the wheel with the maximum wheel speed, means for determining the wheel with the minimum wheel speed- means for determining the differential speed between the maximum wheel speed and the minimum wheel speed and means for comparing the differential speed with a threshold value.
• the wheel speeds are calculated from the speed sensor signals with the aid of additional sensor signals. With the help of the additional sensor signals, it is possible to relate the wheel speeds to the center of gravity of the vehicle or the center of the rear axle.
• These wheel speeds which are related to the center of gravity of the vehicle or the center of the rear axle, are to be precisely monitored for numerous functions, for example for the ABS function (anti-lock braking system) or the ASR function (traction control system).
• ABS function anti-lock braking system
• ASR function traction control system
• the slip of the wheels is monitored on the basis of a logic which is active above the vehicle reference speed of 18 km / h.
• the difference between the slowest and the fastest wheel speed must not be greater than 2 km / h. This value corresponds to 10%.
• the difference must not be greater than 5 km / h. This value corresponds to 5%.
• the permissible differences between 18 km / h and 100 km / h are correspondingly linearly extrapolated or interpolated.
• the slip difference between one wheel and the other three wheels must not be greater than 5%. If the difference is greater than specified by the above limit values, an error counter is incremented. After a certain period of time, for example after 20 s, errors are recognized.
• the invention builds on the generic method in that, if the differential speed is greater than a threshold value, the wheel with the maximum wheel speed is registered as the fastest wheel and the wheel with the minimum wheel speed is registered as the slowest wheel with a change in the wheel speed , so that another bike is the fastest bike and / or another bike is the slowest bike, the fastest bike is registered and the slowest bike is registered and a logical status is determined from the registered values and the current values.
• This wheel logic increases the robustness of the monitoring, since the monitoring does not take place solely on the criteria of the slowest and the fastest wheel speed. Rather, it registers whether the slowest or fastest wheel is being changed. Based on the different cases that A corresponding status can be determined for the logical combinations that occur. On the basis of such a status, a probable number of faulty wheels can then be concluded. Furthermore, an error counter can be incremented or decremented, depending on whether an error and which error is present.
• Status 0 is preferably recognized when the slowest wheel and / or the fastest wheel have changed more than once. If the slowest wheel and / or the fastest wheel changes more than once during monitoring, there is an implausibility as can occur on a special route with an uneven road surface ("washboard"). In any case, if the situation corresponds to status 0, an actual error cannot be concluded.
• Status 1 is advantageously recognized if only the slowest wheel has not changed or if only the fastest wheel has not changed. If, therefore, the slowest or fastest wheel has always been the same wheel, this indicates a single faulty wheel.
• status 2 is recognized when the slowest wheel has changed exactly once and the fastest wheel has changed exactly once. With status 2 there are probably two faulty wheels.
• an error counter is preferably incremented by 2. After a certain period of time, for example after 20 s, errors can thus be identified.
• an error counter is incremented by 1 for status 2. With status 2, for example, errors can be recognized after 40 s.
• the wheel speeds are determined from the speed sensor signals and additional sensor signals.
• the combination of these signals makes it possible to determine wheel speeds related to the center of gravity of the vehicle or the center of the rear axle, which are particularly well suited for monitoring.
• the method according to the invention is particularly advantageous in that the difference in speed is compared with a relative threshold value.
• the relative threshold value can be 5% over the entire speed range between 20 km / h and 100 km / h.
• the differential speed can be compared with an absolute threshold value below a speed threshold.
• the speed threshold below which a constant value is used can be, for example, 40 km / h, a difference speed threshold of, for example, 2 km / h between the slowest and the fastest wheel being the criterion for initiating the monitoring using the wheel logic according to the invention.
• the invention builds on the generic device in that, if the differential speed is greater than a threshold value, the wheel with the maximum wheel speed is registered as the fastest wheel and the wheel with the minimum wheel speed is registered as the slowest wheel with a change in the wheel speed , so that another bike is the fastest bike and / or another bike is the slowest bike, the fastest bike is registered and / or the slowest bike is registered and a logical status is determined from the registered values and the current values.
• the invention is based on the finding that monitoring with improved robustness can be made available by introducing wheel logic. This applies in particular to monitoring the Slip control on special routes ("washboard”) or in other special road conditions, such as in deep snow.
• FIG. 1 shows a flow chart to explain the invention.
• FIG. 1 shows a flow chart to explain the invention.
• the symbols used to designate the process steps have the following meaning:
• SOI Determine the wheel speeds.
• S02 Determine the wheel with the maximum wheel speed.
• S03 Determine the wheel with the minimum
• Wheel speed Determining the differential speed between the maximum wheel speed and the minimum wheel speed. S05 Differential speed greater than threshold? S06 No activation of the wheel logic. S07 Register the wheel with the maximum wheel speed S08: Register the wheel with the minimum wheel speed
• step SOI the wheel speeds of the wheels of a vehicle are determined. These can be determined from the speed sensor signals with the aid of additional sensor signals, so that ultimately wheel speeds are that are related to the center of gravity of the vehicle or the center of the rear axle.
• step S02 the wheel with the maximum wheel speed is determined.
• step S03 the wheel with the minimum wheel speed is determined.
• the order of steps S02 and S03 is arbitrary.
• step S04 the differential speed between the maximum wheel speed and the minimum wheel speed is now determined.
• step S05 it is checked whether the differential speed determined in step SO is greater than a predetermined threshold value. For example, in a speed range between 20 km / h and 100 km / h, it can be monitored whether a relative speed difference is exceeded, for example whether the speeds of the wheel with the maximum wheel speed and the wheel with the minimum wheel speed in relation to the maximum wheel speed by deviate from each other by more than 5%. Below an adjustable speed threshold, for example from 40 km / h, it can be provided that an absolute differential speed is monitored between the slowest and the fastest wheel, for example with a threshold value of 2 km / h.
• a predetermined threshold value for example, in a speed range between 20 km / h and 100 km / h.
• step SO ⁇ If the threshold is not exceeded, the wheel logic is not activated (step SO ⁇ ). However, if the differential speed is greater than the threshold value, the wheel with the maximum wheel speed is registered in step S07. In step S08, the wheel is registered with the minimum wheel speed. Again, the order of steps SO 7 and S08 is irrelevant.
• step SO 9 If the wheel changes with the maximum wheel speed, that is, another wheel now has the maximum wheel speed, this wheel is registered in step SO 9. Likewise, if the wheel changes with the minimum wheel speed, that is to say another wheel now has the minimum wheel speed, this wheel is registered in step S10.
• the order of steps S09 and S10 is arbitrary.
• step S11 the wheel logic according to the invention is now used to check whether the wheel with the maximum wheel speed and the wheel with the minimum wheel speed have always been the same. If this question is answered with yes, this means that no change of the wheel with the minimum wheel speed and the wheel with the maximum wheel speed has taken place, then the logical status 3 is recognized in step S12. In step S13, the error counter is incremented by 2.
• step S14 If the question from step S11 is answered with no, it is checked in step S14 whether the wheel with the maximum wheel speed or the wheel with the minimum wheel speed has always been the same. If this question is answered with yes, it means that only one and If one of the wheels with the maximum wheel speed or the minimum wheel speed has not changed, status 1 is recognized in step S15. In step S16 the error counter is again incremented by 2.
• step S17 checks whether the wheel has been changed once at the slowest wheel speed and whether the wheel speed has also been changed once.
• Step S18 is detected on status 2, and the error counter is incremented by 1 in step S19.
• step S20 If the question from step S17 is answered with no, status 0 is recognized in step S20. This status 0 represents an implausibility as it can occur on a special route ("washboard"). An error cannot be concluded with status 0. The error counter is decremented in step S21.
• status 1 was recognized, there is probably a single faulty wheel. In status 2 there are probably two faulty wheels, and in status 3 one can conclude that one or two faulty wheels exist. After a certain period of time, for example 20 s for status 1 and 3 or 40 s for status 2, an error is recognized. If, on the other hand, status 0 was recognized and the error counter was decremented, the saved wheel indices are deleted when the Error counter is back to 0. The wheel logic is reinitialized.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Regulating Braking Force (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-12-22 DE DE10064503A patent/DE10064503B4/de not_active Expired - Lifetime
• 2001
  • 2001-12-13 EP EP01990301A patent/EP1348131A1/de not_active Withdrawn
  • 2001-12-13 US US10/204,832 patent/US6691060B2/en not_active Expired - Lifetime
  • 2001-12-13 JP JP2002553130A patent/JP4236466B2/ja not_active Expired - Lifetime
  • 2001-12-13 WO PCT/DE2001/004698 patent/WO2002052282A1/de not_active Application Discontinuation

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