Machine element or mechanism – Gearing – Interchangeably locked
Patent
1998-08-10
2000-02-22
Ta, Khoi Q.
Machine element or mechanism
Gearing
Interchangeably locked
477143, 477 86, F16H 6102
Patent
active
060266996
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a gear control for reducing the thermal stress of switching components in a reversing gear for working machines.
In the reversing gears known in the prior art (which are mainly countershaft designs, in which two or more switching components are used for switching a gear and with which a vehicle is capable in the same manner to move in forward and reverse travel directions) the switching components that slip when changing from forward motion to reverse motion, or viceversa, are exposed to high thermal stresses. Since the reversing operation is usually carried out only by a single switching component or a single reversing clutch, the single switching component alone has to absorb the complete power loss or frictional energy.
This high thermal stress requires a correspondingly sturdy design in the switching components, which disadvantageously results in the switching components needing large spaces and being heavy as well as elevated production costs.
DE 18 12 327 discloses a double-clutch transmission for a motor vehicle and a process for adjusting it. The double-clutch transmission has an input shaft and an output shaft which are interconnected by spur toothed gear pairs and are selectively engageable. A first clutch and a second clutch are provided, the first clutch halves being rigidly connected with the input shaft and the second clutch halves with a shaft or a hollow shaft that surrounds the input shaft. Switching means serve to actuate the clutches in order to lead the power flow, in one gear between input and output shafts via the clutch, the shaft, gear-change sleeves and a first set of gear pairs or, in an adjacent gear, via the second clutch, the hollow shaft, the gear-change sleeves and a second set of gear pairs. When starting the motor vehicle, the appertaining clutch and appertaining gear-change sleeve of one gear, and the other clutch and one gear-change sleeve of another gear allocated to the other clutch, are actuated simultaneously. When the output speed of the clutch of one of the gears reaches the input speed thereof, the power flow is interrupted in said gear.
This known process or this double-clutch transmission offers a possibility of reducing the thermal stress of the starting clutch or starting clutches in a double-clutch transmission, resulting from friction.
Even though said proposed process offers the advantage that in a double-clutch transmission the considerable energy generated in the friction linings when starting, which is released in the form of heat, has to be absorbed not by one switching component only, but is instead distributed between two switching components. The distribution, however, takes place uniformly and independently of the existing operating state of the clutch, whereby overheating of a clutch which, for example, already shows greater wear than the other clutch, can occur.
In addition, the process according to DE 38 12 327 disadvantageously can only be used in double-clutch transmissions, the input and output shafts of which are interconnected by spur toothed gear pairs, are selectively engageable, and serve, in particular, for reducing the frictional stress in extreme starting operations.
Accordingly, the present invention is based on the problem of developing a gear control of the above mentioned kind wherein the switching components that take part in the reversal, that is, when changing from forward motion to reverse motion or viceversa, of a countershaft design reversing gear are prevented from thermally overstressing.
The gear control, according to the invention, makes possible the advantageous distribution of thermal stress resulting from the friction between the switching components taking part in the switching operation, whereby they can last longer or be made smaller without being overheated by excessive frictional stress.
This results in the advantage that the space needed, the cost and the weight of the switching components can be substantially reduced.
With the reduction of the friction work and frictional energy in the sw
REFERENCES:
patent: 4090414 (1978-05-01), White
patent: 5036718 (1991-08-01), Bulgrien
patent: 5101688 (1992-04-01), Pearce et al.
patent: 5353662 (1994-10-01), Vaughters
patent: 5367914 (1994-11-01), Ordo
patent: 5450768 (1995-09-01), Bulgrien et al.
patent: 5478289 (1995-12-01), Matsushita et al.
Burkhart Hugo
Dreibholz Ralf
Heitz Uwe
Ta Khoi Q.
ZF Friedrichshafen AG
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