Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid pump and motor in one of plural paths to or from...
Patent
1998-06-25
1999-12-14
Marmor, Charles A
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid pump and motor in one of plural paths to or from...
475 72, 475 80, F16H 4704
Patent
active
06001038&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to methods for controlling a power-dividing transmission, which comprises an adjustable hydrostat unit, a summating planet transmission with at least two outputs, and a downstream motion gear transmission designed as a dual planet transmission, and in which n stages follow one another at synchronous points at which clutches are connected, in which the at least two outputs are connectable to the motion gear transmission via a first clutch or a second clutch and an element of the motion gear transmission is adjustable via a third clutch, and further clutches for further motion gears are provided at the off-take side of the motion gear transmission.
In such transmissions (in the form in which they are known, for example, from EP 386 214 B) the control ensures that in the event of a change in the speed a motion gear change is undertaken in each case at the correct moment. If the change in speed takes place so rapidly that the control is unable to follow (for example in the case of emergency braking), the clutch of the just selected motion gear must be disengaged, in order to prevent the engine from stalling. If the emergency braking is continued until the vehicle is at a standstill, the transmission is brought into the normal position, and the vehicle is able to start off in the first motion gear.
If the emergency braking is not continued until the vehicle is at a standstill then, in the higher motion gears, synchronization of the disengaged clutch is possible by adjustment of the hydrostat. However, in most cases emergency braking is performed almost to standstill. In these circumstances, synchronization is no longer possible, since all clutches must be disengaged. The transmission is situated in an undefined switching position, in which initial synchronization of the first clutch (K1) to be engaged for the lowest gear is not possible. Thus, it is necessary to brake to complete standstill in order to be able to accelerate again. Another undefined switching position is present if, when the gear selector lever is in the neutral position, the vehicle starts to move for example on a slope. In these circumstances as well, according to the prior art it is not possible to engage a motion gear.
Accordingly, the object of the invention is to specify a method of control which in all circumstances ensures the engagement of a motion gear suitable for the instantaneous speed of travel without prior standstill, if an interruption of the power transmission has preceded.
SUMMARY OF THE INVENTION
According to the invention the above object is achieved in that, irrespective of the position of the third clutch and of the further clutches, depending upon the instantaneous speed of travel, the first clutch or the second clutch is synchronized and engaged by adjustment of the hydrostat and either one of the further clutches or the third clutch is synchronized and then engaged.
In the event of an emergency braking which is not performed to complete standstill, the method consists of the steps recited in claim 1; if the vehicle rolls while the transmission is in the neutral position, the method consists of the steps recited in claim 2. In the case of transmissions equipped with a clutch for travel in reverse, the method is analogous, that is to say the same, but if instead of the third clutch, the fourth clutch, that is the one for travel in reverse, is actuated in the same way.
BRIEF DESCRIPTION OF THE DRAWINGS
In the text which follows, the invention is described and explained with reference to illustrations.
FIG. 1 shows a diagram of a transmission which is suitable for carrying out the method according to the invention;
FIG. 2 shows a connection plan;
FIGS. 3 to 5 show the switching positions of the transmission which are run through as the method is performed.
FIGS. 6-9 are flow diagrams showing the different operations for interruption of power transmission, after emergency braking not to standstill, for switching from low speed to higher motion gear, and for travel in r
REFERENCES:
patent: 4168637 (1979-09-01), Orshanshy, Jr. et al.
patent: 4261226 (1981-04-01), Orshanshy, Jr. et al.
patent: 4363247 (1982-12-01), Weseloh
patent: 5267911 (1993-12-01), Meyerle
patent: 5683322 (1997-11-01), Meyerle
Leitner Josef
Wontner Gebhard
Lund Scott
Marmor Charles A
Steyr-Daimler-Puch Aktiengesellschaft
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