Method of preventing skid of wheels of a vehicle

Claim 2

An anti-skid method of preventing skid of wheels of a vehicle comprising: detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle, setting from the detected vehicle speed a first reference wheel-speed signal (U R ) and a second reference wheel-speed signal (Vwo) of a level lower than that of said first reference wheel-speed (U R ) for comparison with said wheel-speed signal (Uwi), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel acceleration for comparison with said wheel-acceleration signal(Uwi), comparing, during braking, said wheel-speed signal (Uwi) with said first and second reference wheel-speed signals (U R , Vwo) and also said wheel-acceleration signal (Uwi) with said reference wheel-deceleration signal (-Vwo), and controlling a braking torque (T B ) applied to said wheel such that said brake torque (T B ) is maintained constant from the time when the level of said wheel-acceleration signal (Uwi) falls below the level of said reference wheel-deceleration signal (-Vwo) if the level of said wheel-speed signal (Uwi) is higher than that of said first reference wheel-speed signal (U R ), and thereafter, said brake torque (T B ) is reduced from the first instant when the level of said wheel-speed signal (Uwi) falls below the level of said first reference wheel-speed signal (U R ) if the level of said wheel-acceleration signal (Uwi) remains below the level of said reference wheel-deceleration signal (-Vwo), or at the second instant when the level of said wheel-speed signal (Uwi) falls below the level of said second reference wheel-speed signal (Vwo), the reduction of said brake torque (T B ) taking place at an earlier one of said first and second instants.

Claim 3

An anti-skid method as claimed in claim 1, in which said brake torque (T B ) is continued to reduce for a preset period of time from the instant when the level of said wheel-speed signal (Uwi) falls below the level of said second reference wheel-speed signal (Vwo) after said brake torque (T B ) begins to reduce.

Claim 4

An anti-skid method as claimed in claims 1, 2, comprising detecting the peripheral speeds of a plurality of wheels of said vehicle, and determining said vehicle-speed from the highest one of the detected peripheral speeds and a preset rate of attenuation of the vehicle speed.

Claim 5

An anti-skid method of preventing skid of the wheels of a vehicle comprising: detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle, setting a reference wheel-speed signal (U R ) from the detected vehicle speed for comparison with said wheel-speed signal (Uwi), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said wheel-speed signal (Uwi) with said reference wheel-speed signal (U R ) and also said wheel-acceleration signal (Uwi) with said reference wheel-deceleration signal (-Vwo), controlling a braking torque (T B ) applied to said wheel such that torque is maintained constant when the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U R ) and simultaneously the level of said wheel-acceleration signal (Uwi) is lower than that of said reference wheel-deceleration signal (-Vwo); and further comprising the steps of reducing the brake torque when the level of the wheel-speed signal is lower than that of the reference wheel-speed signal and simultaneously when the level of the wheel-acceleration signal is lower than that of the reference wheel-deceleration signal.

Claim 6

An anti-skid method of preventing skid of the wheels of a vehicle comprising: detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle, setting a reference wheel-speed signal (U R ) from the detected vehicle speed for comparison with said wheel-speed signal (Uwi), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said wheel-speed signal (Uwi) with said reference wheel-speed signal (U R ) and also said wheel-acceleration signal (Uwi) with said reference wheel-deceleration signal (-Vwo), controlling a braking torque (T B ) applied to said wheel such that torque is maintained constant when the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U R ) and simultaneously the level of said wheel-acceleration signal (Uwi) is lower than that of said reference wheel-deceleration signal (-Vwo); and further comprising the steps of reducing the brake torque when the level of the wheel-speed signal is lower than that of the reference wheel-speed signal and simultaneously when the level of the wheel-acceleration signal is lower than that of the reference wheel-deceleration signal.

Claim 7

An anti-skid method as claimed in claim 4 in which the reduction of said brake torque (T B ) is halted at the instant when the level of said wheel-acceleration signal (Uwi) rises above the level of said reference wheel-deceleration signal (-Vwo) as a result of the increasing acceleration of said wheel caused due to the reduction of said brake torque (T B ).

Claim 8

An anti-skid method as claimed in claim 4 comprising: picking up said vehicle speed as a vehicle-speed signal (U), setting a low reference vehicle-speed signal (Uo) for comparison with said vehicle-speed signal (U), and a reference wheel-acceleration signal (Vw1 or Vw2) representative of a positive wheel acceleration for comparison with said wheel-acceleration signal (Uwi), and controlling said brake torque (T B ) in a manner such that as long as the level of said vehicle-speed signal (U) is greater than that of said low reference vehicle-speed signal (Uo), the reduction of said brake torque (T B ) is halted at the instant when the level of said wheel-acceleration signal (Uwi) rises above the reference wheel-acceleration signal(Vw1 or Vw2) as a result of the increasing acceleration of said wheel caused due to the reduction of said brake torque (T B ).

Claim 9

An anti-skid method as claimed in claim 4 comprising: setting a reference wheel-acceleration signal (Vwi or Vw2) for comparison with said wheel-acceleration signal (Uwi), and controlling said brake (T B ) in a manner such that after said brake torque (T B ) begins to reduce, the reduction of said brake torque (T B ) is ceased at the instant when the level of said wheel-acceleration signal (Uwi) rises above the level of said wheel-deceleration signal (-Vwo) if the level of said wheel-speed signal (Uwi) is lower than that of said reference wheel-speed signal (U R ), and thereafter, said brake torque (T B ) is maintained constant as long as the level of said wheel-acceleration signal (Uwi) is higher than that of said reference wheel-deceleration signal (-Vwo) and lower than that of said reference wheel-acceleration signal (Vw1 or Vw2) if the level of said wheel-speed signal (Uwi) is lower than that of said reference wheel-speed signal (U R ).

Claim 10

An anti-skid method of preventing skid of the wheels of a vehicle comprising: detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle and picking it up as a vehicle-speed signal (U), determining a reference wheel-speed signal (U R ) based on said vehicle-speed signal (U) for comparison with said wheel-speed signal (Uwi), setting a low reference vehicle-speed signal (Uo) for comparison with said vehicle-speed signal (U), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said vehicle-speed signal (U), said wheel-speed signal (Uwi) and said wheel-acceleration signal (Uwi) with said low reference vehicle-speed signal (Uo), said reference wheel-speed signal (U R ) and said reference wheel-deceleration signal (-Vwo), respectively, and controlling a brake torque (T B ) applied to said wheel such that as long as the level of said vehicle-speed signal (U) is greater than that of said low reference vehicle-speed signal (Uo), said brake torque (T B ) is maintained constant from the instant when the level of said wheel-acceleration signal (Uwi) falls below the level of said reference wheel-deceleration signal (-Vwo) if the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U R ), and thereafter, said brake torque (T B ) is reduced from the instant when the level of said wheel-speed signal (Uwi) falls below that of said reference wheel-speed signal (U R ) if the level of said wheel-acceleration signal (Uwi) remains below the level of said reference wheel-deceleration signal (-Vwo), and said brake torque (T B ) is permitted to increase freely at the instant when the level of said vehicle-speed signal (U) is decreased below the level of said low reference vehicle-speed signal (Uo).

Claim 11

An anti-skid method of preventing skid of the wheels of a vehicle comprising: detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle and picking it up as a vehicle-speed signal (U), determining a reference wheel-speed signal (U R ) based on said vehicle-speed signal (U) for comparison with said wheel-speed signal (Uwi), setting a low reference vehicle-speed signal (Uo) for comparison with said vehicle-speed signal (U), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said vehicle-speed signal (U), said wheel-speed signal (Uwi) and said wheel-acceleration signal (Uwi) with said low reference vehicle-speed signal (Uo), said reference wheel-speed signal (U R ) and said reference wheel-deceleration signal (-Vwo), respectively, and controlling a brake torque (T B ) applied to said wheel such that as long as the level of said vehicle-speed signal (U) is greater than that of said low reference vehicle-speed signal (Uo), said brake torque (T B ) is maintained constant from the instant when the level of said wheel-acceleration signal (Uwi) falls below the level of said reference wheel-deceleration signal (-Vwo) if the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U R ), and thereafter, said brake torque (T B ) is reduced from the instant when the level of said wheel-speed signal (Uwi) falls below that of said reference wheel-speed signal (U R ) if the level of said wheel-acceleration signal (Uwi) remains below the level of said reference wheel-deceleration signal (-Vwo), and said brake torque (T B ) is permitted to increase freely at the instant when the level of said vehicle-speed signal (U) is decreased below the level of said low reference vehicle-speed signal (Uo).

Claim 12

An anti-skid method as claimed in claim 8 comprising: setting a first reference wheel-acceleration signal (Vw1) for comparison with said wheel-acceleration signal (Uwi), and controlling said brake torque (T B ) in a manner such that, if the level of said vehicle-speed signal (U) is higher than that of said low reference vehicle-speed signal (Uo), the reduction of said brake torque (T B ) is halted at the instant when the level of said wheel-acceleration signal (Uwi) rises above the level of said first reference wheel-acceleration signal (Vw1) as a result of the increasing acceleration of said wheel after said brake torque (T B ) begins to reduce.

Claim 13

An anti-skid method as claimed in claim 8 comprising: setting a second reference wheel-acceleration signal (Vw2) of a level higher than that of said first reference wheel-acceleration signal (Vw1), and controlling said brake torque (T B ) in a manner such that said brake torque (T B ), after beginning to reduce, is maintained constant as long as the level of said wheel-acceleration signal (Uwi) is higher than that of said first reference wheel-acceleration signal (Vw1) and lower than that of said second reference wheel-acceleration signal (Vw2) if the level of said wheel-speed signal (Uwi) is lower than that of said reference wheel-speed signal (U R ).

Claim 14

An anti-skid method as claimed in claim 8 comprising detecting the peripheral speeds of a plurality of wheels of said vehicle, and determining said vehicle-speed from the highest one of the detected peripheral speeds and a preset rate of attenuation of the vehicle speed.