Road surface gradient detecting apparatus

• US 6,510,374 B1
• Filed: 05/08/2001
• Issued: 01/21/2003
• Est. Priority Date: 05/26/2000
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Saotome, Hiroshi, Fujimoto, Shuichi, Miyazaki, Tetsushi
• Primary Examiner(s): Nguyen, Tan Q.
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/850,077
• Time in Patent Office: 623 Days
• Field of Search: 701/80, 701/87, 701/84, 701/51, 701/54, 701/94, 701/68, 701/53, 701/58, 701/65, 701/69, 701/36, 477/107, 477/115, 477/169, 477/174
• US Class Current: 701/80
• CPC Class Codes: F16H 2059/142 of driving resistance calculated from weight, slope, or the like
• CPC Class Codes: F16H 2059/385 Turbine speed
• CPC Class Codes: F16H 2059/467 of torque converter
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: F16H 61/20 Preventing gear creeping ; Transmission control during standstill, e.g. hill hold control

Abstract

When a road surface gradient is calculated by a wheel driving force and a vehicle acceleration, if the wheel driving force is calculated based on an output torque of an engine, the accuracy of calculating the wheel driving force, i.e., the road surface gradient becomes poor due to deterioration by aging of the engine or the like. In order to solve this kind of disadvantage, a fluid transmission torque of a torque converter is calculated by those torque ratio of the torque converter and an input shaft torque coefficient which correspond to a speed ratio of the torque converter, and an input rotational speed of the torque converter (=engine rotational speed (step S21-3). The road surface gradient is calculated by using a wheel driving force to be calculated by this torque.

Claims

1. A road surface gradient detecting apparatus for use in a vehicle in which wheels are driven by an engine through a power transmission device having interposed therein a torque converter containing therein a lock-up clutch, said road surface gradient being calculated by a wheel driving force and a vehicle acceleration, said apparatus comprising:

a first driving force calculating means for calculating, while the lock-up clutch is not in operation, the wheel driving force based on that fluid transmission torque of the torque converter which is obtained by a speed ratio of the torque converter and an input rotational speed of the torque converter;

a second driving force calculating means for calculating, while the lock-up clutch (2a) is in operation in a direct-coupled state, the wheel driving force based on an engine output torque; and

a third driving force calculating means for calculating, while the lock-up clutch is in operation in a slipping state, the wheel driving force based on a total torque of;

that fluid transmission torque of the torque converter which is obtained by the speed ratio of the torque converter and the input rotational speed of the torque converter;

and that transmission torque of the lock-up clutch which is calculated by an engaging force of the lock-up clutch, whereby the road surface gradient is calculated by the wheel driving force which is calculated by the driving force calculating means corresponding to the state of the lock-up clutch.

2. The road surface gradient detecting apparatus for use in a vehicle according to claim 1, wherein said wheel driving force is corrected by deduction depending on a braking force, said braking force being calculated based on the hydraulic pressure of a brake during a depression of a brake pedal.