Search

EP-4425011-B1 - METHOD FOR CHANGING OVER TRANSMISSION STAGES OF A TRANSMISSION ARRANGEMENT

EP4425011B1EP 4425011 B1EP4425011 B1EP 4425011B1EP-4425011-B1

Inventors

  • BRIX, NORMAN
  • VOGEL, DIETER
  • Arcolia, Alessandro
  • Alberti, Andrea
  • HERRMANN, RONNY
  • Barrera Villalpando, Abraham
  • Klee, Hannes
  • Isfort, Ole
  • WERNER, FRANZ
  • MUELLER, MATTHIAS
  • MUMCU, Peer
  • ILK, ERICH

Dates

Publication Date
20260506
Application Date
20230303

Claims (11)

  1. A method for changing over transmission stages (46, 48) of a transmission arrangement (3) of a mobile working machine, the transmission arrangement (3) comprising: a first hydraulic machine (8) coupled to a drive machine (2), a second hydraulic machine (14) having an adjustable expulsion volume (VH), wherein the second hydraulic machine (14) is fluidically connected to the first hydraulic machine (8) via a first working line (10) of the transmission arrangement (3) and a second working line (12) of the transmission arrangement (3), wherein the second hydraulic machine (14) is coupled to a manual transmission (6) of the transmission arrangement (3) so that a torque can be transmitted, the manual transmission (6) having at least two transmission stages (46, 48), the method being characterized in that it comprises the following steps: a) requesting a changeover of an engaged transmission stage (46, 48) from a first transmission stage (46, 48) to a second transmission stage (46, 48); b) identify a first time interval, wherein said first time interval is the time requested for said changeover from said first transmission stage (46, 48) to said second transmission stage (46, 48); c) estimating the velocity the mobile working machine would reach at the end of said changeover based on said first time interval identified during said step b); d) enabling or disabling said changeover based on said estimated velocity.
  2. Method according to claim 1, wherein in said step c) for estimating said velocity an acceleration or a deceleration of the mobile working machine is considered.
  3. Method according to any of claims 1 or 2, wherein said method comprises further the following steps: e. Identify a second time interval, wherein said second time interval is the time requested for detecting a condition that would cause a request of abortion of said changeover; f. estimating the velocity reached by said mobile working machine after said second time interval; wherein in said step d. the changeover is disabled if the estimated velocity in said step f. and the actual velocity have a different sign.
  4. Method according to any of claims 1 to 3, wherein an actual load at said second hydraulic machine (14) is detected, wherein said load is compared with a reference range, wherein if the actual load is outside said reference range, in said step d said changeover is disabled.
  5. Method according to claim 4, wherein said reference range is determined in function of the actual driving velocity of said mobile working machine.
  6. Method according to claim 5, wherein lower driving velocities of said mobile working machine said reference range is smaller.
  7. Method according to any of said claims 1 to 6, wherein in said step d) the changeover is disabled if it is detected that a changeover is actually being carried out.
  8. Control unit (28) adapted to perform a method according to any one of claims 1 to 7.
  9. A mobile working machine comprising a transmission arrangement (3), the transmission arrangement (3) comprising a first hydraulic machine (8) coupled to a drive machine (2) and a second hydraulic machine (14) having an adjustable expulsion volume (VH), wherein the second hydraulic machine (14) is fluidically connected to the first hydraulic machine (8) via a first working line (10) of the transmission arrangement (3) and a second working line (12) of the transmission arrangement (3), wherein the second hydraulic machine (14) is coupled to a manual transmission (6) of the transmission arrangement (3) so that a torque can be transmitted, the manual transmission (6) having at least two transmission stages (46, 48), wherein the mobile working machine comprises a control unit (28) according to claim 8.
  10. Computer program adapted to execute the method according to any one of claims 1 to 7.
  11. Machine-readable storage medium having a computer program stored thereon according to claim 10.

Description

TECHNICAL FIELD The present invention relates to the technical field of a transmission arrangement having a hydrostatic transmission and a mechanical manual transmission. In particular, the present invention relates to a method for changing over transmission stages of the transmission arrangement. PRIOR ART A transmission arrangement having a hydrostatic transmission and a mechanical manual transmission which is coupled in series therewith is used in travel drives, for example those of agricultural machines or working machines. Automation permits transmission stages of the manual transmission of such transmission arrangements to shift even during travel. For this purpose, the torque between the hydraulic motor of the hydrostatic transmission and the transmission input of the manual transmission is lowered to zero. This is done by reducing the expulsion volume of the hydraulic motor to zero ("zero oscillation"). When the zero expulsion volume is reached, the old transmission stage is disengaged and the new transmission stage is engaged by means of mechanical synchronization. Many methods have been developed for enabling a smooth transmission procedure. Three different examples are described in the following patent documents: DE 10 2016 215 992 A, DE 2020 20 107 297 U1 and IT 10 2020 000006952 A1. For all the described methods, the core of the strategy is represented by the fact that, depending on the actual velocity of the mobile machine, after having received from the driver a request for changing a transmission stage, the changeover of the transmission stage is enabled or disabled based on said actual velocity. EP 2 213 910 A describes another process for changing gears in a multi-speed transmission driven by a hydrostatic gearbox. The main problem, which occurs during transmission is that sometimes, after the changeover between a first transmission stage and a second transmission stage is already started, the changeover has to be aborted, since some working parameters become outside predetermined ranges. In particular, a gear change on mobile machines always means a change in tractive force, and in the case of particularly low-cost transmission designs even an interruption in tractive force. A reduction or interruption of the tractive force when driving uphill can lead to the machine stopping or even rolling back, depending on the load and gradient. Such a behavior would lead the machine to automatically abort the changeover, which has been already started, which would cause an undesirable and for the driver behavior of the machine At the same time, when driving downhill, a reduction in tractive force or interruption even manifests itself in reduced hydrostatic braking, which can result in critical situations for the driver and persons standing next to him. Such a behavior it totally critical and should be prevented to occur. Objective of the present invention is, therefore, to provide a method for changing over transmission stages of a transmission arrangement, which enables to overcome the above-mentioned problems. SUMMARY According to the present invention a method for changing over transmission stages (46, 48) of a transmission arrangement (3) of a mobile working machine is provided, the transmission arrangement (3) comprising: a first hydraulic machine (8) coupled to a drive machine (2),a second hydraulic machine (14) having an adjustable expulsion volume (VH), wherein the second hydraulic machine (14) is fluidically connected to the first hydraulic machine (8) via a first working line (10) of the transmission arrangement (3) and a second working line (12) of the transmission arrangement (3), wherein the second hydraulic machine (14) is coupled to a manual transmission (6) of the transmission arrangement (3) so that a torque can be transmitted, the manual transmission (6) having at least two transmission stages (46, 48), the method being characterized in that it comprises the following steps: a) requesting a changeover of an engaged transmission stage (46, 48) from a first transmission stage (46, 48) to a second transmission stage (46, 48);b) identify a first time interval, wherein said first time interval is the time requested for said changeover from said first transmission stage (46, 48) to said second transmission stage (46, 48);c) estimating the velocity the mobile working machine would reach at the end of said changeover based on said first time interval identified during said step b);d) enabling or disabling said changeover based on said estimated velocity. With enabling and disabling the changeover it is meant that the changeover is respectively allowed or not allowed to occur based on said estimated velocity. Said first transmission stage and said second transmission stage can be respectively one between the lower and the higher transmission stage. For each of the two cases a different value of the first time interval will be used (respectively for downshifting and for upshifting). In the st