Boots – shoes – and leggings
Patent
1990-07-20
1994-03-29
Black, Thomas G.
Boots, shoes, and leggings
364565, 73510, 180197, G01P 342
Patent
active
052991318
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is known to measure the speed of vehicle wheels by means of sensors and to use the measured speeds to control the wheel slippage. Wheel slippage can be caused by overbraking of wheels (brake slippage), too great a drive torque (drive slippage) or by the drag torque of the engine when the friction coefficient between road and tire is too small. In an ABS, the brake slippage is controlled by changing the brake pressure In a drive slip control (ASR), the drive slippage is controlled by changing the drive torque and/or the brake. In an engine drag torque control, the slippage is controlled by changing the drive.
The tires of a vehicle may have different diameters and thus different wheel speeds can be measured at the individual wheels. This can lead to an inaccuracies in the above mentioned control procedures.
From European patent A2 0133381 to which U.S. Pat. No. 4,566,737 corresponds, it is know to detect during travel different tire diameters by difference formation of wheel speed signals and to correct the measured speed values of wheels with different tire diameters. For controlling purposes, the resulting values can be set into relation to one another.
SUMMARY OF THE INVENTION
Determining the vehicle speed in accordance with the invention ensures a very good approach to the situation.
The detection of diameter differences of the wheels and the correcting calculations are preferably carried out when there is no braking, when none of the control procedures is being carried out, when not driving through a curve (small steering angle signal or small transverse acceleration or approximately the same rotating speed at the wheels and the axles), when the vehicle acceleration or deceleration is small, when the wheels are not at all or only slightly accelerated or decelerated and/or when only a small engine torque is coupled to the driven wheels. The latter can be signaled by a small engine output torque or no connection between engine and driven wheels or, in case of an automatic transmission, when setting the lever to the "N-position." In ABS controls, the zero torque determination is not possible by means of DKV- and n.sub.mot -scan since this is ASR-specific information.
Instead, in case of ABS control, it is possible to read in the line to the fuel consumption display (KVA) of an already present injection system (Motronic, Jetronic, or the like). The values are approximately proportional to the injection time T.sub.i. Knowing the corresponding engine characteristics, it is possible to determine the engine torque from T.sub.i or KVA. The above criteria can be used in different combinations in order to determine the slippage-free wheel run. It is also possible to carry out the measuring and correcting merely in an average speed range.
The change of the dynamic wheel diameter is a non-linear function of the vehicle speed. In order to carry out a non-linear correction, a correction by means of speed-dependent correction values over the entire speed range is possible.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram for the working of the method in accordance with the invention,
FIG. 2 is a flow diagram for the working of the method,
FIGS. 3 and 4 are an explanatory table and diagram, respectively,
FIG. 5 is a block diagram of another embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the FIG. 1, the speed sensors 1-4 associated with the four wheels of a vehicle supply wheel speeds V.sub.1 to V.sub.4 to a block 5. A further block 6 activates block 5, if, as it is assumed here, there is no braking (BLS), ABS and ASR are not in operation (ABS and ASR), the vehicle acceleration or deceleration is smaller by a prescribed value a.sub.1, the transverse acceleration a.sub.Q is smaller than a value a.sub.2 and if the vehicle moves at a speed between 20 and 110 km/h (12 and 70 mph).
If these conditions are met, a slippage free travel is assumed. It is assumed that the criterion a.sub.Q is smaller than a.sub.2 and that it is added only later, prompted by a su
REFERENCES:
patent: 4032197 (1977-06-01), Kohler
patent: 4484280 (1984-11-01), Brugger et al.
patent: 4566737 (1986-01-01), Masaki et al.
patent: 4873638 (1989-10-01), Shiraishi et al.
patent: 4933855 (1990-06-01), Leiber et al.
patent: 4933857 (1990-06-01), Hashiguchi et al.
Bedrna Frank
Brauninger Jurgen
Guttler Hans
Haas Hardy
Leibbrand Norbert
Black Thomas G.
Park Collin W.
Robert & Bosch GmbH
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