Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1988-03-01
1989-08-08
Diehl, Dwight G.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74862, B60K 4106
Patent
active
048541940
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an automatic transmission control system for such a vehicle as a dump truck and, more particularly, to a starting speed stage selector which is used in such a transmission control system to select an optimum speed stage of a vehicle for starting a vehicle.
BACKGROUND ART
In general, an automatic transmission control system for a vehicle is arranged to shift the speed of a transmission up or down to optimum one of preset speed stages sequentially on a step-by-step basis in accordance with the load condition of the vehicle (such as, for example, the vehicle speed or engine rotational speed).
In prior art automatic transmission control systems of the type referred to, however, when a transmission lever is set at a shift position D (drive position) with speed stages ranging from a forward 2 speed position to a forward 7 speed position (F2 to F7) and it is desired to start a vehicle, the vehicle must be started always from the position F2 and be shifted up in speed on a step-by-step basis in a sequential order of F2, F3, F4, . . . and up to the optimum speed stage, which disadvantageously results in that the system requires the large number of shift times, with poor start/acceleration characteristics and considerable speed shift shock.
In view of the above circumstances, it is an object of the present invention to provide a starting speed stage selector which is used in an automatic transmission control system to allow a vehicle to start always from an optimum speed stage in response to load conditions of the vehicle.
DISCLOSURE OF INVENTION
The present invention is featured by comprising means for detecting a start mode of a vehicle, means for detecting loaded conditions of the vehicle, means for detecting an incline angle of the vehicle with respect to a front and rear direction, means for selecting optimum one of the speed stages in a start mode of the vehicle on the basis of outputs of the load condition detecting means and the incline angle detecting means, and speed control means for controllably changing the speed stage of a transmission to the optimum speed selected by the starting-speed-stage selecting means in the start mode of the vehicle when the start mode detecting means detects the start mode.
That is, the present invention is arranged to measure the load conditions of the vehicle at the time of starting the vehicle on the basis of a road surface gradient, a carried load or cargo condition and so on, to select an optimum speed stage (a speed stage providing the best start/acceleration characteristics) in response to the measured load conditions, and to start the vehicle from the selected speed stage.
In accordance with such an arrangement of the present invention, the number of speed shift times, especially, under a low load condition can be reduced and good start/acceleration properties can be obtained. In addition, torque variations, which would tend to take place at low speed stages, can be made small and speed shift shock can be avoided.
BRIEF DESCRIPTION OF DRAWINGS:
FIG. 1 is an arrangement showing an embodiment of an automatic transmission control system including a starting speed stage selector of the present invention;
FIG. 2 is a flowchart for explaining the operation of the transmission control system of FIG. 1;
FIG. 3 is a diagram for explaining an example of normal automatic transmission control; and
FIGS. 4 and 5 are explanatory diagrams for explaining another example of the automatic transmission control.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be detailed by referring to attached drawings.
Referring first to FIG. 1, there is shown an arrangement of an automatic speed change gear or transmission control system including a starting speed stage selector of the present invention, in which system a transmission lever 1 is used to select one of speed shift positions (R, N, D, 5, 4, 3 and 2) and a shift position sensor 2 is to send to an automatic transmission control unit 6 a position signal indica
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Kaneko Kiyoshi
Kato Yoshiaki
Diehl Dwight G.
Kabushiki Kaisha Komatsu Seisakusho
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