Transmission device and method for operating the same

Patent metadata

Field	Value
Publication number	US-10066745-B2
Application number	US-201715413523-A
Country	US
Kind code	B2
Filing date	Jan 24, 2017
Priority date	Jan 25, 2016
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

A power-split transmission device for a vehicle, which connects a drive engine to a drive output, having a hydrostatic unit for continuous adjustment of the transmission ratio at a transmission unit, and two range clutches that alternately operate for respectively associated driving ranges with different transmission ratios. A control unit, during regular vehicle deceleration, implements the driving range change from a first range, with higher transmission ratios, to a second range, with lower transmission ratios, by switching from the first to the second range clutch in accordance with a synchronous point dependent deceleration control logic. In the special case of an unexpected increase of the deceleration dynamic at the beginning of an already initiated driving range change from the first to the second driving range, the control unit immediately forces the change by bypassing the synchronous point dependent deceleration control logic when other boundary conditions are fulfilled.

First claim

The invention claimed is:

1. A power-split transmission device for a vehicle, designed to connect a drive engine, arranged on an input side, to a drive output, arranged on an output side, the power-split transmission device comprising:
a hydrostatic unit for continuous adjustment of a transmission ratio at a transmission unit, and
at least first and second range clutches that cooperate with the transmission unit and are substantially operated in alternation for respectively associated first and second driving ranges with different transmission ratios,
a control unit, in a normal case of a regular vehicle deceleration, implements a driving range change from the first driving range, with higher reciprocal transmission ratios, to the second driving range, with lower reciprocal transmission ratios, by switching over from the first range clutch to the second range clutch in accordance with a synchronous point dependent deceleration control logic, and
in a special case of an unexpected increase of a deceleration dynamic at a beginning of an already initiated driving range change, from the first driving range to the second driving range, the control unit immediately forces the change by bypassing the synchronous point dependent deceleration control logic.

2. The power-split transmission device according to claim 1 , wherein the first and the second range clutches are hydraulically actuated disk clutches, and the control unit controls a supply of hydraulic oil to the first and the second range clutches.

3. The power-split transmission device according to claim 2 , wherein to initiate a driving range change , the control unit pre-fills the first range clutch with hydraulic oil, in order to bring clutch disks of the first range clutch already into mutual contact without producing friction locking of the first range clutch.

4. The power-split transmission device according to claim 1 , wherein the control unit deduces an existence of the special case of the unexpected increase of the deceleration dynamic at the beginning of the already initiated driving range change, from a corresponding increase in loading of the drive engine.

5. A method of operating a power-split transmission device for a vehicle which connects a drive engine, arranged on an input side, to a drive output, arranged on an output side, and has a hydrostatic unit for continuous adjustment of a transmission ratio at a transmission unit, and at least first and second range clutches that cooperate with the transmission unit and are substantially operated, in alternation, for respectively associated first and second driving ranges with different transmission ratios, and a control unit that, in a normal case of a regular vehicle deceleration, implements a driving range change from a first driving range, with higher reciprocal transmission ratios, to a second driving range, with lower reciprocal transmission ratios, by switching over from the first range clutch to the second range clutch, the method comprising process steps of:
a) determining a time interval before reaching a synchronous point for the driving range change,
b) pre-filling of the first range clutch with hydraulic oil,
c) in the normal case of a still regular vehicle deceleration, the driving range change is completed by completely engaging the first range clutch in accordance with a synchronous point dependent deceleration control logic, whereas
d) in a special case of an unexpected increase of a deceleration dynamic at a beginning of an already initiated driving range change, the first range clutch is immediately engaged thereby bypassing the synchronous point dependent deceleration control logic.

6. The method according to claim 5 , further comprising keeping the second range clutch closed until a lapse of an overlap time in which the first range clutch is also still closed.

7. The method according to claim 6 , further comprising for the force driving range change triggered as a result of the special case, reducing at least one of an overlap time of the first and the second range clutches and a subsequent holding time in comparison with an overlap time and holding time specified for the normal case.

8. The method according to claim 5 , further comprising determining the special case of an unexpected increase of the deceleration dynamic at the beginning of an already initiated driving range change from a deviation of a calculated time interval for reaching the synchronous point for the driving range change and an expected earlier arrival at the synchronous point.

9. The method according to claim 5 , further comprising determining the special case of an unexpected increase of the deceleration dynamic at the beginning of an already initiated driving range change from a plurality of characteristic deceleration dynamics parameters that characterize corresponding external loading, and the plurality of characteristic deceleration dynamics parameters comprising:
an actual drive output rotational speed gradient of the transmission device,
at least one of an engine rotational speed gradient and a rotational speed of the drive engine,
an engine torque of the drive engine,
a pressure in the hydrostatic unit, and
a decrease of a nominal reciprocal transmission ratio of the transmission device ( 1 ).

10. The method according to claim 5 , further comprising, before reaching the synchronous point, defining a threshold value for the closing of the first range clutch, beyond which the first range clutch receives the closing signal, in order to compensate for inertia-related clutch delay, such that the threshold value is adaptable in accordance with the driving situation.

11. The method according to claim 5 , further comprising determining the special case of the unexpected increase of the deceleration dynamic at the beginning of the already initiated driving range change from an onset of an occurrence of a reversing demand immediately before an upshift of the transmission device.

12. The method according to claim 5 , further comprising determining the special case of the unexpected increase of the deceleration dynamic at the beginning of the already initiated driving range change from a detection of a position of at least one of an accelerator pedal and a brake pedal of the vehicle.

13. The method according to claim 5 , further comprising determining the special case of the unexpected increase of the deceleration dynamic at the beginning of the already initiated driving range change from a detection by a sensor of a current position of either a lifting frame or a scoop of the vehicle, in order to recognize a forthcoming drive up a mound.

14. The method according to claim 5 , further comprising determining the special case of the unexpected increase of the deceleration dynamic at the beginning of the already initiated driving range change from a current condition of the vehicle selected from the group comprising:
driving on a road,
driving up a mound, and
a loading condition of the vehicle.

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Geiger Simon
• Madlener Matthias
• Bieber Sven

Classifications

• B60Y2200/415

  Wheel loaders · CPC title

• F16H47/02 Primary

  the fluid gearing being of the volumetric type · CPC title

• B60Y2400/72

  Continous variable transmissions [CVT] · CPC title

• F16H61/40 Primary

  hydrostatic · CPC title

• B60K2025/026

  by a hydraulic transmission · CPC title