Motor vehicles – Steering by driving – Endless flexible track
Patent
1997-11-18
2000-03-07
Schwartz, Christopher P.
Motor vehicles
Steering by driving
Endless flexible track
180 944, 701 41, 701 42, 701 50, B62D 1102
Patent
active
060327510
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a cross-drive steering transmission for a tracklaying vehicle, in particular a cross-drive steering transmission having several fixed reduction gears.
For the control of tracklaying vehicles, a difference of speed of the two driving chains is produced, whereby a turning radius appears in which the ratio of the inner radius to the outer radius corresponds to the speed ratio of the inner to the outer chain. To produce said speed difference, cross-drive steering transmissions are used which superimpose the designed speed difference, between right and left chains, to the actual propulsion.
The cross-drive steering transmissions, for presently known tracklaying vehicles, can be divided in two categories: addition, partly have at their disposal a small infinitely variable range for large radii; and infinitely variably over the entire, or at least a large, range.
The mechanical steering transmission advantageously stands out by its low cost, high efficiency, simple design and short reaction time, but has the disadvantage of possessing no infinitely variable range, or only a very small one, which results in stiff demands on the driver and relatively expensive safety devices against torque overloads.
The hydrostatic or hydrodynamic steering transmissions, as result of their large, infinitely variable steering range, impose only slight demands on the driver and can be easily secured against torque overloads, but due to the complex design, the costs are elevated, the efficiency is low and the reaction time long.
DE-A 36 19 055 has disclosed a mechanical cross-drive steering transmission with three radius ranges. Said transmission is comprised of a partial hydrostatic and a partial mechanical transmission. A zero shaft of the steering transmission cooperates with summarizing gears of the main transmission. In a first radius range, the partial hydrostatic transmission is exclusively active, in a second radius range the partial mechanical transmission is additionally active and in a third fixed radius the partial mechanical transmission is exclusively active.
The problem to be solved by the invention is to develop a mechanical cross-drive transmission so that, on one hand, the above described advantages are retained and, on the other, a large infinitely variable steering range results.
The problem is solved by the features of claim 1.
Accordingly, a conventionally designed mechanical steering transmission is used which has an automatic steering radius switching means and a control wherein, according to the driver's steering radius input, switching is automatically produced by the control between the existing fixed steering radii in such a manner that the desired arc (with a corresponding radius) is approximated by a plurality of arc segments (with fixed radii).
The invention is described in more detail in the figures with the aid of an embodiment having one mechanical three-radii steering transmission. There is, in addition, represented what follows. In the drawings:
FIG. 1 is a gear diagram of a steering transmission;
FIG. 2 is a diagram of the tracklaying vehicle transmission;
FIG. 3 is a hydraulic diagram;
FIG. 4 is an operation diagram;
FIG. 5 shows steering radius =f (rotation angle on the steering gear);
FIG. 6 is a digital/analog change-over range;
FIG. 7 is a break down of steering angle;
FIGS. 8 and 9 show steering strategy;
FIG. 10 shows cornering;
FIG. 11 shows steering strategy;
FIG. 12 shows the steering transmission disconnection conditions; and
FIG. 13 shows the steering transmission protection "reset" condition.
FIG. 1 shows a gear diagram of the steering transmission as an example. The steering transmission is comprised essentially of a conventional, primarily driven three-radii steering transmission with three fixed radius reduction gears and an infinitely variable radius range for large steering radii. The infinitely variable radius is obtained by driven slippage in the clutch KR1/2/3 and controlled by a mechanically actuated, hydraulic steering control piston.
FIG. 2 shows the
REFERENCES:
patent: 5569109 (1996-10-01), Okada
Loichinger Walter
Sorg Johannes
Bartz C. T.
Schwartz Christopher P.
ZF Friedrichshafen AG
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