Vehicle performance advisory system

Claim 2

A performance advisory system for a powered vehicle having a multi-ratio transmission, comprising an electronic control unit (20) responsive to engine torque to indicate when the driver can shift to a higher gear, characterised in that the control unit (20) responds to engine speed and engine torque to calculate in accordance with the gear ratios of the transmission the highest gear which will maintain the existing ground speed without the engine torque exceeding a predetermined maximum torque and without the engine speed falling below a predetermined minimum speed, and by display means (22) which display the calculated gear and the corresponding engine speed.

Claim 3

A performance advisory system according to claim 1, characterised in that the electronic control unit (20) comprises a memory containing data representing an engine torque-speed characteristic of the engine and derives the engine torque from engine speed and from the engine torque-speed characteristic.

Claim 4

A performance advisory system according to claim 2, characterised in that the electronic control unit (20) calculates proposed engine speeds and proposed torques corresponding to gear ratios higher than the current gear ratio and such that the current vehicle travel speed would be maintained thereby and compares the proposed torques to the maximum torque and compares the proposed engine speeds to the minimum engine speed.

Claim 5

A performance advisory system according to claim 3, characterised in that the current engine torque Ti is determined from the equation: where Tm is the predetermined maximum torque, Nf is a fast idle speed of the engine at maximum govenor setting, Nr is a rated speed of the engine and Ni is the current speed of the engine.

Claim 6

A performance advisory system according to claim 3 or 4, characterised in that the proposed engine speeds Nj are determined by the equation: Nj = Ni x ((GR)i/ (GR)j), where Ni is the current engine speed, (GR) i is the current gear ratio and (GR)j is the proposed gear ratio.

Claim 7

. A method for selecting an optimum gear ratio setting and reduced engine speed for-an engine-driven vehicle having a multi-ratio transmission, characterised by the steps of: a) determining the actual gear ratio (GP)i of the transmission; b) determining the actual engine speed Ni of the vehicle; c) deriving an actual torque value Ti from the actual engine speed and from a known characteristic of the engine; d) designating proposed gear ratios (GR)j which are higher than the actual gear ratio (GR)i; e) determining proposed engine speeds Nj according to the equation: Nj = Ni ((GR)i/(GR)j); f ) determining proposed torque values Tj according to the equation: Tj = Ti (Ni/Nj); g) comparing the proposed torque values Tj to a predetermined maximum torque value; h) comparing the proposed engine speed value Nj to a predetermined minimum engine speed value; .i) selecting the highest of the proposed gear ratios such that the corresponding proposed torque value is less than the . predetermined maximum torque value and such that the corresponding proposed engine speed is greater than the predetermined minimum engine speed; and j) displaying to a vehicle operator the selected proposed gear ratio and its corresponding proposed engine speed.

Claim 8

. A method for selecting an optimum gear ratio setting and reduced engine speed for-an engine-driven vehicle having a multi-ratio transmission, characterised by the steps of: a) determining the actual gear ratio (GP)i of the transmission; b) determining the actual engine speed Ni of the vehicle; c) deriving an actual torque value Ti from the actual engine speed and from a known characteristic of the engine; d) designating proposed gear ratios (GR)j which are higher than the actual gear ratio (GR)i; e) determining proposed engine speeds Nj according to the equation: Nj = Ni ((GR)i/(GR)j); f ) determining proposed torque values Tj according to the equation: Tj = Ti (Ni/Nj); g) comparing the proposed torque values Tj to a predetermined maximum torque value; h) comparing the proposed engine speed value Nj to a predetermined minimum engine speed value; .i) selecting the highest of the proposed gear ratios such that the corresponding proposed torque value is less than the . predetermined maximum torque value and such that the corresponding proposed engine speed is greater than the predetermined minimum engine speed; and j) displaying to a vehicle operator the selected proposed gear ratio and its corresponding proposed engine speed.