Machine element or mechanism – Gearing – With fluid drive
Reexamination Certificate
1999-12-17
2001-03-13
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
With fluid drive
Reexamination Certificate
active
06199450
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a transmission, and more specifically to a method and apparatus for adaptively controlling clutches based on a torque converter ratio.
BACKGROUND OF THE INVENTION
Powershift transmissions are used in a variety of work machines where it is desirable to shift gears without interrupting the torque flow through the transmission. To this end, transmissions generally have a clutch overlap period whereby both an first speed clutch and a second speed clutch are engaged at the same time. If this overlap period is too short, then there will be a significant torque interruption to an output shaft prior to the engagement of the on-coming clutch. If the overlap period is too long, then the shift will expose the transmission to stresses which can potentially reduce the life of various transmission components. Additionally, transmissions may also have a directional clutch which bears most of the load during a shift between the first speed clutch and the second speed clutch. Therefore, it is also important to control the rate and timing of the engagement of the directional clutch with respect to the speed clutches to ensure that the load is properly carried by the directional clutch during the shift.
A single timing of the disengagement of the first speed clutch, engagement of the second speed clutch, and the disengagement and reengagement of a directional clutch is not satisfactory for all load conditions. In particular, under high load conditions, it is desirable to increase the overlap period between the first speed clutch and the second speed clutch, increase the rate at which the second speed clutch is engaged, and increase the rate at which the directional clutch is reengaged to effectively complete the gear shift. On the other hand, under light load conditions, it is desirable to decrease the overlap period between the first speed clutch and the second speed clutch, and reduce the rate at which the directional clutch is engaged to effectively complete the shift. Moreover, the pressure used to hold and engage the speed clutches and directional clutches may also be varied to improve the shift. Under high load conditions, it is desirable to increase the engagement pressures of the second speed clutch and directional clutch whereas under low load conditions, it is desirable to decrease the engagement pressures of the second speed clutch and directional clutch.
What is needed therefore is a method and apparatus for adaptively engaging speed and directional clutches based on transmission load.
DISCLOSURE OF THE INVENTION
In accordance with a first embodiment of the present invention, there is provided a drive line assembly for a work machine. The drive line assembly includes an engine driving an engine output shaft and an engine speed sensor which generates engine speed signals indicative of a speed of the engine output shaft. The drive line assembly further includes a torque converter driven by the output shaft which drives a transmission input shaft and a transmission speed sensor which generates transmission speed signals indicative of a speed of the transmission input shaft. The drive line assembly yet further includes a transmission driven by the transmission input shaft and having a first speed clutch, a second speed clutch, and a directional clutch, and a controller. The controller is operable to determine a torque converter ratio from the engine speed signal and the transmission speed signal and determine an engine load based on the torque converter ratio. The controller is further operable to control engagement of the first speed clutch, the second speed clutch and the directional clutch based on the engine load.
In accordance with a second embodiment of the present invention, there is provided a method controlling a drive line assembly. The drive line assembly includes (i) an engine driving an engine output shaft, (ii) an engine speed sensor which generates engine speed signals indicative of a speed of the engine output shaft, (iii) a torque converter driven by the output shaft which drives a transmission input shaft, (iv) a transmission speed sensor which generates transmission speed signals indicative of a speed of the transmission input shaft, (v) a transmission driven by the transmission input shaft and having a first speed clutch, a second speed clutch, and a directional clutch, and (vi) a controller. The method includes the steps of determining a torque converter ratio from the engine speed signal and the transmission speed signal with the controller and determining an engine load based on the torque converter ratio with the controller. The method further includes the step of controlling engagement of the first speed clutch, disengagement of the second speed clutch and disengagement and reengagement of the directional clutch based on the engine load with the controller.
REFERENCES:
patent: 3673400 (1972-06-01), Ito
patent: 3752011 (1973-08-01), Casey et al.
patent: 3765271 (1973-10-01), Dach et al.
patent: 4480502 (1984-11-01), Nembach
patent: 4843916 (1989-07-01), Bouta
patent: 4977797 (1990-12-01), Aoki et al.
patent: 5309790 (1994-05-01), Tanaka
patent: 5454767 (1995-10-01), Clausen et al.
patent: 5475591 (1995-12-01), Suzuki et al.
patent: 5510982 (1996-04-01), Ohnishi et al.
patent: 5588936 (1996-12-01), Uchida et al.
patent: 5688207 (1997-11-01), Uchida et al.
Carlson Douglas A.
Hussain Danish A.
Stahl Alan L.
Caterpillar Inc.
Morrison John W.
Wright Dirk
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