Machine element or mechanism – Gearing – Interchangeably locked
Patent
1997-10-02
2000-03-14
Ta, Khoi Q.
Machine element or mechanism
Gearing
Interchangeably locked
477 86, 477174, B60K 4128
Patent
active
060357347
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to gearboxes for motor vehicles.
It is known that some of the vehicles on the market today are equipped with "manual" gearboxes, and others are equipped with "automatic" gearboxes.
In a manual gearbox, the gear ratio engaged is chosen unambiguously by the driver, by means of a suitable lever, and the gears are selected or changed mechanically and directly by the lever.
Conversely, in an automatic gearbox, the driver has access, via a lever, only to a choice of a forward drive mode (low gear or high gear), a reverse drive mode, or a disengaged or neutral position (also referred to as "park"). On this basis, a module automatically moves the gearbox through both directions in which the gear ratios change, i.e. going both up through the gear ratios and down through them, without the driver being able to impose a precise choice of gear.
Automatic gearboxes are quite well accepted by certain drivers. However, they are not universally liked. In particular, they are not very well accepted in Latin countries.
In recent years, some companies have proposed vehicles equipped with "semi-automatic" gearboxes.
Accompanying FIG. 1 is a diagram showing the overall structure of such a conventional semi-automatic gearbox system.
Such a system includes a conventional gearbox 10 provided with actuators 20, which are generally fluid-driven servo-controlled actuators, suitable for acting on the gearbox 10 to change gears on the basis of instructions issued by a control assembly 30. The control assembly 30 comprises a manually-actuated control lever 32 and control transducers 34 that respond to the control lever 32 being displaced by defining gear change instructions. The control assembly 30 is associated with an electronic module 40 which receives the above-mentioned change instructions generated by the control transducers 34. The electronic module 40 controls the actuators 20 associated with the gearbox 10. In addition, the electronic module 40 is generally connected to sensors, e.g. a vehicle speed sensor 50, so that the electronic module 40 controls execution by the actuators 20 of the change instructions issued by the control assembly 30 as a function of the speed of the vehicle. For this purpose, the electronic module 40 applies instructions output by the control assembly 30 to the actuators 20 only if said instructions are compatible with the operating conditions of the vehicle.
The driver thus remains in control of choosing which gear ratio is engaged, because the driver acts on the lever 32 to request a change of gear (going up through the gears or going down through them, or else a change to reverse gear). However, the electronic module 40 oversees the system as a whole, and it authorizes a gear change only if the operating conditions of the vehicle are compatible with the change.
Such semi-automatic gearbox systems offer numerous advantages over other prior systems:
they make driving more comfortable;
they make it possible to omit the clutch pedal, as with an automatic gearbox;
they make it possible to change gear without taking the foot off the accelerator, when provision is made to integrate the gearbox system into the engine control system;
they can be implemented at an intermediate cost between the cost of a manual gearbox and the cost of an automatic gearbox;
they fully maintain the pleasure of driving;
they make it possible to improve fuel consumption, power, and engine wear as compared with manual gearboxes;
they extend the life-spans of the various members;
they improve driving safety as compared with manual gearboxes; and
they are compatible with conventional manual gearboxes.
However, in spite of all those advantages, semi-automatic gearbox systems have not been as commercially successful as expected.
Document GB-A-2 119 460 describes a semi-automatic transmission control with an automatic mode.
Document EP-A-0 547 598 describes a control device for a gearbox having manual and automatic control using automatic speed-change diagrams stored in memory.
An object of the present inven
REFERENCES:
patent: 4638898 (1987-01-01), Braun
patent: 4971183 (1990-11-01), Tellert
Magneti Marelli France
Ta Khoi Q.
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