METHOD AND CONTROL DEVICE FOR OPERATING A POWER TAKEOFF

Abstract

A method for operating an auxiliary power take-off (5) in a drive-train of a motor vehicle with at least a drive aggregate (1) and with a transmission (2) connected between the drive aggregate (1) and an axle drive (4). To operate the power take-off (5,) a transmission gear is engaged in the transmission (2). During an uninterrupted operation of the power take-off (5), after lapse of a defined time period, an automatic shift to a protective gear is carried out in the transmission (2).

Claims

1-10. (canceled)

11. A method for operating an auxiliary power take-off (5) in a drive-train of a motor vehicle having at least a drive aggregate (1) and an axle drive (4), and a transmission (2) connected between the drive aggregate (1) and the axle drive (4), the method comprising: engaging an initial transmission gear in the transmission (2) to operate the power take-off (5); and during uninterrupted operation of the power take-off (5) in the initial transmission gear in the transmission, after a lapse of a defined time period, automatically shifting to a protective gear in the transmission (2).

12. The method according to claim 11, further comprising only shifting the transmission (2) to the protective gear for a specifiable time, and, after lapse of the specifiable time, automatically re-engaging the initial transmission gear.

13. The method according to claim 11, further comprising interrupting operation of the power take-off (5) with the protective gear engaged in the transmission (2) by a torque demand of an operator of the vehicle.

14. The method according to claim 11, further comprising carrying out the automatic shift to the protective gear, before the lapse of the defined time period, if an auxiliary unit driven by the power take-off (5) is operated under reduced power.

15. The method according to claim 14, further comprising re-engaging the initial transmission gear in the transmission (2), if a higher torque from the drive aggregate (1) for operating the power take-off (5) is requested by an operator of the vehicle.

16. The method according to claim 11, further comprising informing an operator of the vehicle about the automatic shift into the protective gear.

17. The method according to claim 11, further comprising operating the drive aggregate (1) in such manner that a rotational speed of a power take-off shaft (9), when the protective gear is engaged in the transmission (2), corresponds to a rotational speed of the power take-off shaft (9) before the automatic shift to the protective gear.

18. A control device for operating an power take-off (5) in a drive-train of a motor vehicle with at least a drive aggregate (1) and a transmission (2) connected between the drive aggregate (1) and an axle drive (4), the control device comprises at least a receiving interface designed to receive input signals from drive-train components; an evaluation unit for evaluating the input signals received; and a sender interface for emitting control signals to drive-train components; for the operation of the power take-off (5), the control device controlling an actuator system by which an initial transmission gear is engaged in the transmission (2), and, after lapse of a defined time period of uninterrupted power take-off (5) operation, the control device activating an actuator system by which a protective gear is engaged in the transmission (2).

19. The control device according to claim 18, wherein the control device carries out by control means engaging an initial transmission gear in the transmission (2) to operate the power take-off (5); and during uninterrupted operation of the power take-off (5) in the initial transmission gear in the transmission, automatically shifting to the protective gear in the transmission (2) after the lapse of the defined time period.

20. A computer program product with program code means which is stored on a computer-readable data carrier and which is run on a control device according to claim 18 such that when the computer program product is run on the control device for the operating of the power take-off (5), the control device controls an actuator system by which an initial transmission gear is engaged in the transmission (2), and after lapse of a defined time period of uninterrupted power take-off (5) operation, the control device activates an actuator system by which a protective gear is engaged in the transmission (2).

21. A computer program product with program code means which is stored on a computer-readable data carrier and which is run on a control device for operating an power take-off (5) in a drive-train of a motor vehicle with at least a drive aggregate (1) and a transmission (2) connected between the drive aggregate (1) and an axle drive (4), the control device having at least a receiving interface designed to receive input signals from drive-train components; an evaluation unit for evaluating the input signals received; and a sender interface for emitting control signals to drive-train components; such that when the computer program product is run on the control device for the operating of the power take-off (5), the control device controls an actuator system by which an initial transmission gear is engaged in the transmission (2), and after lapse of a defined time period of uninterrupted power take-off (5) operation, the control device activates an actuator system by which a protective gear is engaged in the transmission (2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Preferred further developments emerge from the subordinate claims and the description below. An example embodiment of the invention, to which it is not limited, is explained in greater detail with reference to the sole drawing. The sole drawing shows an example of a drive-train scheme of a motor vehicle in the form of a utility vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The sole FIGURE shows a schematic drive-train of a motor vehicle in the form of a utility vehicle, with a drive aggregate 1 in the form of an internal combustion engine or combustion engine.

[0037] In addition, the motor vehicle comprises a transmission 2 and a transfer case 3, which are connected between the drive aggregate 1 and an axle drive 4.

[0038] The transmission 2 can for example be in the form of an automatic transmission or an automated manual transmission. When the transmission is designed as an automated manual transmission, as is known a clutch (not shown here) can be connected between the drive aggregate 1 in the form of an internal combustion engine and the transmission 2. When the clutch is open, the drive aggregate 1 is decoupled from the transmission 2, whereas in contrast when the clutch is closed, the drive aggregate 1 is coupled to the transmission 2.

[0039] The drive aggregate 1 engages with a transmission input shaft 6 of the transmission 2. The axle drive 4 is coupled to a drive output shaft 8 of the transfer case 3. Furthermore, a transmission output of the transmission 2 and a transmission input of the transfer case 3 are coupled to one another via a shaft 7. Consequently, the transfer case 3 can be built between the transmission 2 and the axle drive 4 in the cardan shaft line. The axle drive 4 can for example comprise a rear-axle differential.

[0040] The motor vehicle in the form of a utility vehicle further comprises at least one auxiliary power take-off (PTO) 5. The power take-off 5 concerned engages with a power take-off shaft 9 of the transfer case 3. Torque for driving the power take-off 5 can be applied to the power take-off shaft 9.

[0041] For example, the drive-train may be a drive-train of a fire-fighting vehicle. In that case, by way of the power take-off or power take-offs, auxiliary units such as pumps, foam proportioning systems or water cannons, or fire booms can be operated. The drive energy of the drive aggregate 1 must be matched optimally to the fire-fighting technology of the fire-fighting vehicle.

[0042] This power transfer can take place for example by way of a transfer case 3 in the form of a so-termed split-shaft transmission. By means of the split-shaft transmission all of the power from the drive aggregate 1 can be supplied to the fire-fighting auxiliary units. For this purpose, the axle drive 4 is decoupled via the split-shaft transmission and the drive power of the drive aggregate 1 is made available for operating the at least one power take-off 5. In this way the fire-fighting auxiliary units can be operated for long periods.

[0043] To operate the auxiliary units, a gear is engaged in the transmission 2 and the power take-off 5 is coupled to the power take-off shaft 9 of the transfer case 3 by means of a shifting element (not shown here), which can be an interlocking or a frictional shifting element.

[0044] In the event of uninterrupted operation of the power take-off, it is now provided that after the lapse of a defined time period, a forced gearshift into a protective gear is carried out automatically in the transmission 2.

[0045] In that way transmission elements can be relieved of load, so that shortening the life of or damage to the transmission can be prevented.

INDEXES

[0046] 1 Drive aggregate

[0047] 2 Transmission

[0048] 3 Transfer case

[0049] 4 Axle drive

[0050] 5 Auxiliary power take-off

[0051] 6 Transmission input shaft

[0052] 7 Transmission output shaft

[0053] 8 Transmission output shaft of the transfer case

[0054] 9 Power take-off shaft of the transfer case