Instrument for measuring the speed and fuel consumption of motor vehicles

摘要

An instrument for continuously indicating the instantaneous rate of fuel consumption (e.g. in terms of liters per 100 kilometers) during operation of a motor vehicle comprises a stationary speed scale juxtaposed with a movable consumption scale, the two scales carrying relatively inverted logarithmic graduations and being swept by a common pointer driven through a gear train from a speedometer biased by a spring of logarithmic characteristic. The movable scale is magnetically entrained, via a friction coupling, by a flowmeter which is thermostatically controlled to take changes in fuel viscosity due to temperature variations into account; the friction coupling can be manually preadjusted in accordance with the specific weight of the fuel. The pointer and the movable scale are carried by two coaxial disks that coact through a differential coupling with a switch which energizes different signal lamps according to whether, at a given speed, the rate of fuel consumption is normal, subnormal or excessive.