Endless belt power transmission systems or components – Control for variable input to output speed-ratio
Patent
1997-06-30
2000-04-18
Walsh, Donald P.
Endless belt power transmission systems or components
Control for variable input to output speed-ratio
474 28, 477101, F16H 900
Patent
active
060509139
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Such a system is described in FIG. 1 and is known, for example, from EP-A-0 451 887. This publication too relates to the adjustment of the tension of a belt means 1, usually a belt, in a continuous belt transmission 2 comprising belt means 1, a drive pulley 3 and an output pulley 4 which is driven by an engine 11.
To adjust the transmission ratio of a continuously variable belt transmission and the tension of the belt means 1, the drive pulley 3 comprises an axially stationary conical pulley 7 and an axially moveable conical pulley 9 and the output pulley 4 comprises an axially stationary conical pulley 8 and an axially moveable conical pulley 10. The drive pulley 3 is also known as the primary pulley and the output pulley 4 is also known as the secondary pulley. Pressing of the axially moveable conical pulley halves 9 and 10 against the belt means 1 takes place in response to the build-up of a hydraulic pressure in the respective oil chambers 5 and 6. The desired transmission ratio of the continuously variable belt transmission and the required tension of the belt means 1 can be adjusted by a suitable selection of the applied pressures P.sub.prim and P.sub.sec in the oil chambers 5 and 6. For the force transmission from the engine 11 to the drive pulley 3, a torque converter 12 and a planetary assembly 13 can, for example, be provided with clutches for forward and rearward travel. The engine 11 can also drive the pump 14 of the continuously variable belt transmission. A transmission control 18 comprises the electrical and hydraulic components for driving the continuously variable belt transmission. The transmission control 18 includes means for adjusting the pressure in the oil chamber 6 or in the oil chambers 5 and 6.
The tension of the belt means 1 is adjusted in one embodiment of the transmission control 18 utilizing the pressure P.sub.sec in the output end oil chamber 6.
The tension of the transmission means 1 is so adjusted that the efficiency of the continuously variable belt transmission is a maximum. On the one hand, it is to be prevented that the belt means 1 suddenly slips because of too low a tension and, on the other hand, the tension of the belt means 1 must not be too high in order to avoid high losses in the continuously variable belt transmission. To reconcile the two requirements, the torque transmitted from the drive pulley 3 to the output pulley 4 must be known as precisely as possible. The torque to be transmitted on the drive pulley 3 is determined primarily by the torque of the engine 11 and the torque amplification factor of the torque converter 12.
In EP-A-0 451 887, a method for adjusting the pressure P.sub.sec in the output end oil chamber 6 is described. In this method, the rotational angle .alpha..sub.Dk of the throttle flap 15 of the engine 11 is detected by a sensor 16. Furthermore, the rpm N.sub.mot of the engine 11, the rpm N.sub.prim of the primary pulley 3 and the rpm N.sub.sec of the secondary pulley 4 are measured with rpm sensors 19, 20 and 21 and conducted as corresponding signals to the transmission control 18. The angle position .alpha..sub.Dk of the throttle flap is measured by the sensor 16. The angle position .alpha..sub.Dk, the engine rpm N.sub.mot, the primary rpm N.sub.prim, and the secondary rpm N.sub.sec are utilized in the transmission control 18 to adjust the tension of the belt means 1 by adjusting the pressure in the oil chamber 6.
To adjust the tension of the belt means 1, the engine torque to be expected is estimated with a characteristic field of the throttle flap angle and the engine rpm. The engine torque to be expected is converted into an expected primary torque in a characteristic field with the formed quotient of the primary rpm and the engine rpm. Thereafter, the computation of the required pressure P.sub.sec takes place in the output end oil chamber to adjust the tension of the belt element 1.
The use of the throttle flap angle .alpha..sub.Dk to estimate the torque has the disadvantage that the calibration of the t
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Patent Abstracts of Japan, vol. 13, No. 385 (M-864), Aug. 1989.
Luh Joachim
Luyckx Johan
Pelders Rine
Reuschenbach Lutz
Senger Karl-Heinz
Marcelo Emmanuel M.
Ottesen Walter
Robert & Bosch GmbH
Walsh Donald P.
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