Method of automatic gear selection in a vehicle power transmission
First Claim
1. A method for generating a gear selection signal in a vehicle having an engine, a mechanical power transmission which includes a plurality of gears, and a storage means for storing a plurality of gear selection tables, each said gear selection table including a respective upper and lower speed limit for each of said gears, said method comprising the steps of:
- storing for each of a plurality of time intervals, a set of values representative of the speed of said vehicle, the acceleration of said vehicle, and the load of said engine during the respective time interval;
selecting one of said gear selection tables as a function of said stored values which relate to the engine load and acceleration of said vehicle at least 0.5 seconds before the most recently stored speed value; and
generating a gear selection signal indicative of that gear whose respective upper and lower speed limits, as defined by said selected gear selection table, encompasses the most recently sensed speed value.
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Accused Products
Abstract
Method for automatic gear selection in a vehicle power transmission, said selection being catered for by a control system including an electronic unit (1) which, in response to signals representing vehicle speed and engine load, coacts with a programmable read-only memory PROM (28), in which there are stored, for each gear position, alternative speed limits for changing gear to neighboring gears and also limiting values relating to speed change and engine load for selection between said alternative speed limits. To eliminate the risk of unsuitable gear selection for heavy vehicles, e.g. in conjunction with changing gear on a hill, the invention is essentially distinguished in that during travel, data on speed change and engine load are stored in a random access memory RAM (29); that the speed value most recently stored in said RAM before the initiation of the gear selection is compared, together with values stored in said RAM and relating to speed change and engine load at a certain instant before the initiation of the speed change, with values stored in said PROM and relating to speed, speed change and engine load, respectively; that said comparison results in the choice of a certain gear; that in the electronic unit (1) there is generated an output signal representing the selected gear; and that said output signal is fed to an operative means for indicating and/or engaging the selected gear.
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Citations
12 Claims
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1. A method for generating a gear selection signal in a vehicle having an engine, a mechanical power transmission which includes a plurality of gears, and a storage means for storing a plurality of gear selection tables, each said gear selection table including a respective upper and lower speed limit for each of said gears, said method comprising the steps of:
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storing for each of a plurality of time intervals, a set of values representative of the speed of said vehicle, the acceleration of said vehicle, and the load of said engine during the respective time interval; selecting one of said gear selection tables as a function of said stored values which relate to the engine load and acceleration of said vehicle at least 0.5 seconds before the most recently stored speed value; and generating a gear selection signal indicative of that gear whose respective upper and lower speed limits, as defined by said selected gear selection table, encompasses the most recently sensed speed value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for generating a gear selection signal in a vehicle having an engine, a mechanical power transmission including a plurality of gears, and a storage means for storing a plurality of gear selection tables, each said gear selection table including a respective upper and lower speed limit for each of said gears, said method comprising the steps of:
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sensing, during each of a plurality of successive time intervals, a speed value of said vehicle, and a load value of said engine and storing said sensed values; calculating for each said time interval an acceleration value of said vehicle as a function of said sensed speed value associated with that time interval and said sensed speed value associated with the prior said time interval; selecting one of said gear selection tables as a function of said stored load and acceleration values which values are associated with at least one of said time intervals which will relate to engine load and vehicle acceleration at least 0.5 seconds before the most recent said time interval; and generating a gear selection signal indicative of that gear whose respective upper and lower speed limits, as defined by said selected gear selection table, encompasses the most recently sensed speed value. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification