METHOD AND TRANSMISSION CONTROL APPARATUS FOR OPERATING A MULTIPLE-SPEED VEHICLE TRANSMISSION

Abstract

Disclosed is method for operating a multi-gear vehicle transmission having a plurality of shifting elements (A, B, C, D, E) for engaging gears of the vehicle transmission. In a neutral gear a transmission input (1) and a transmission output (2) of the vehicle transmission are decoupled from one another. In a driving gear the transmission input (1) and the transmission output (2) of the vehicle transmission are coupled with one another by closing the shifting elements (A, B, C, D, E) associated with the driving gear in order to propel the vehicle. When the neutral gear is engaged, a transmission condition is determined, and if a transmission condition with elevated drag losses exists, then in addition to the shifting elements (A, B, C, D, E) of a driving gear, at least one further shifting element (A, B, C, D, E) of the vehicle transmission is closed.

Claims

1-11. (canceled)

12. A method for operating a multi-gear vehicle transmission having shifting elements (A, B, C, D, E) configured for engaging gears of the vehicle transmission, the method comprising: decoupling a transmission drive input (1) from a transmission drive output (2) of the vehicle transmission when the vehicle transmission is in a neutral gear; coupling the transmission drive input (1) and the transmission drive output (2) of the vehicle transmission when in a driving gear by closing shifting elements (A, B, C, D, E) associated with the driving gear in order to propel the vehicle; determining whether a transmission condition with elevated drag losses exists when the neutral gear is engaged; and closing at least one further shifting element (A, B, C, D, E) of the vehicle transmission, if the transmission condition with elevated drag losses exists, in addition to closing the shifting elements (A, B, C, D, E) associated with the driving gear.

13. The method according to claim 12, wherein determining whether the transmission condition with elevated drag losses exists takes into account at least one of (i) a transmission temperature, (ii) an operating duration of the vehicle transmission since starting a motor of a drive motor that is or can be coupled to the vehicle transmission, and (iii) a temperature model of the vehicle transmission.

14. The method according to claim 13, wherein determining whether the transmission condition with elevated drag losses exists takes into account at least the transmission temperature, determined by taking into account a lubricant temperature of the vehicle transmission.

15. The method according to claim 13, wherein determining whether the transmission condition with elevated drag losses exists takes into account at least the transmission temperature and wherein determining the transmission temperature is performed using a temperature sensor.

16. The method according to claim 12, wherein if the transmission condition with elevated drag losses exists, the method comprises: closing shifting elements (A, B, C) of a forward gear; closing shifting elements (A, B, D) of a reversing gear, wherein the shifting elements (A, B, C) of the forward gear differ from the shifting elements (A, B, D) of the reversing gear by only one shifting element (C, D).

17. The method according to claim 16, comprising: opening the shifting element (D) of the reversing gear, which is not one of the shifting elements (A, B, C) of the forward gear, when the forward gear is called for, wherein the forward gear is already engaged by virtue of the shifting elements (A, B, C) of the vehicle transmission still being closed.

18. The method according to claim 16, comprising: opening the shifting element (C) of the forward gear which is not one of the shifting elements (A, B, D) of the reversing gear when the reversing gear is called for, whereupon the reversing gear is already engaged by virtue of the shifting elements (A, B, D) of the vehicle transmission still being closed.

19. The method according to claim 12, comprising: determining whether an operating temperature of the vehicle transmission has been reached or exceeded; and engaging the neutral gear of the vehicle transmission if the operating temperature of the vehicle transmission has been reached or exceeded.

20. The method according to claim 19, comprising determining the operating temperature using a temperature sensor.

21. A transmission control unit configured to carry out a method according to claim 12.

22. The transmission control unit of claim 21 comprising computer-readable code that when executed by the transmission control unit, causes the control unit to carry out the method according to claim 12.

23. A vehicle transmission comprising the transmission control unit according to claim 22.

24. A motor vehicle comprising the vehicle transmission according to claim 23.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Below, the invention is explained in greater detail with reference to figures, from which preferred embodiments and features of the invention emerge, and which show:

[0029] FIG. 1: A schematic representation of an automatic transmission of planetary design;

[0030] FIG. 2: An example of a shifting scheme for the automatic transmission in FIG. 1;

[0031] FIG. 3: A schematic representation of a further automatic transmission of planetary design; and

[0032] FIG. 4: An example of a shifting scheme for the automatic transmission in FIG. 3.

DETAILED DESCRIPTION

[0033] FIG. 1 shows a diagram of an example of an automatic transmission of a motor vehicle, wherein a drive aggregate (not shown) is coupled to a transmission input 1 of the automatic transmission and a drive output of the motor vehicle (not shown) is coupled to a transmission output 2 of the automatic transmission.

[0034] The automatic transmission shown in FIG. 1 is of planetary design and comprises a total of eight shafts 3, 4, 5, 6, 7, 8, 9, and 10, the shaft 3 being a transmission input shaft and the shaft 4 being a transmission output shaft. The shafts 3 to 10 of the automatic transmission of FIG. 1 are in driving connection on the one hand by way of gearsets 11, 12, 13, and 14, and on the other hand by way of transmission-internal shifting elements A, B, C, D, and E.

[0035] The automatic transmission shown in FIG. 1 has four gearsets 11, 12, 13, and 14 and five shifting elements A, B, C, D, and E, the shifting elements A and B being in the form of brakes and the shifting elements C, D, and E being in the form of clutches. With the automatic transmission shown in FIG. 1 a total of eight forward gears and one reversing gear can be engaged, and in each of the said gears three shifting elements are closed and two shifting elements are open. To carry out a gearshift, and thus to carry out a shifting process, at least one of the previously open shifting elements A, B, C, D, and E of the automatic transmission is closed or engaged and at least one of the previously closed shifting elements A, B, C, D, and E is opened or disengaged. The transmission layout shown in FIG. 1 is presented purely as an example. For example, in addition to frictional shifting elements interlocking shifting elements can also be present.

[0036] FIG. 2 shows an example of a shifting scheme for the automatic transmission in FIG. 1. In each gear three of the shifting elements A, B, C, D, and E. are closed and two of the shifting elements A, B, C, D, and E are open. The shifting elements are in the form of brakes A, B and clutches C, D, E.

[0037] The first forward gear is obtained by closing the brakes A and B and the clutch C, the second forward gear by closing the brakes A and B and the clutch E, the third forward gear by closing the brake B and the clutches C and E, the fourth forward gear by closing the brake B and the clutches D and E, the fifth forward gear by closing the brake B and the clutches C and D, the sixth forward gear by closing the clutches C, D, and E, the seventh forward gear by closing the brake A and the clutches C and D, and the eighth forward gear by closing the brake A and the clutches D and E. The reversing gear is obtained by closing the brakes A and B and the clutch D.

[0038] According to the invention, an undesired rolling condition of the vehicle caused by elevated drag losses of the vehicle transmission can be prevented. During a possible actuation of the multi-gear vehicle transmission, for example, the following steps can be carried out: [0039] 1. The neutral gear of the vehicle transmission is called for, for example automatically, or by a driver who has switched the driving switch to the “neutral” driving switch position. [0040] 2. When the neutral gear is called for, first of all a transmission condition of the vehicle transmission is determined. If a transmission condition with elevated drag losses exists, then in addition to the shifting elements A, B, C of a driving gear, so that in this case the driving gear considered is the first forward gear, at least one of the further shifting elements D, E of the vehicle transmission is actuated in the closing direction. By closing at least one of the two clutches D, E the vehicle transmission is braced or blocked and in that way the motor vehicle is kept at a standstill. Preferably however, only the clutch D of the vehicle transmission is additionally closed in order to achieve the bracing or blocking of the transmission. Thus, four shifting elements A, B, C, D of the vehicle transmission are actuated, of which the shifting elements A, B, C are shifting elements of the first gear and the shifting elements A, B, D are shifting elements of the reversing gear. The brakes A, B are thus closed both for the first gear and for the reversing gear. [0041] 3. If then the driver calls for the first gear as a starting gear, the shifting element D of the reversing gear is opened. Since the shifting elements A, B, C of the first gear are already closed, the first gear is engaged by opening the clutch D and the vehicle can move off immediately. [0042] 4. If instead of the first gear the driver calls for the reversing gear, then the shifting element C of the first gear is opened. Since the shifting elements A, B, D of the reversing gear are already closed, opening the clutch C engages the reversing gear and the vehicle can move in reverse immediately. [0043] 5. If the operating temperature of the vehicle transmission has been reached before the driver calls for a driving gear, then in the vehicle transmission the neutral gear is engaged. For this the two clutches C, D are opened and the brake B is pre-filled, while the brake A remains closed. If the vehicle transmission has reached its operating temperature, the drag losses of the vehicle transmission while the neutral gear are so low that the vehicle does not change to an undesired rolling condition.

[0044] FIG. 3 shows a second example transmission layout of an automatic transmission for a motor vehicle, wherein a drive aggregate (not shown) can be coupled to a transmission input 15 of the automatic transmission and a transmission output 16 of the automatic transmission can be coupled to a drive output (not shown) of the motor vehicle.

[0045] The automatic transmission shown in FIG. 3 is of planetary design and comprises a total of six shafts 17, 18, 19, 20, 21, and 22, the shaft 19 being a transmission input shaft and the shaft 22 being a transmission output shaft. The shafts 17 to 22 of the automatic transmission in FIG. 3 are in driving connection on the one hand by way of gearsets 23, 24, and 25 and on the other hand by way of transmission-internal shifting elements A2, B2, C2, D2, and E2,

[0046] The automatic transmission shown in FIG. 3 has three gearsets 23, 24 and 25 and five shifting elements A2, B2, C2, D2, and E2, wherein the shifting elements A2 and B2 are in the form of clutches and the shifting elements C2, D2, and E2 are brakes. With the automatic transmission shown in FIG. 3 a total of six forward gears and one reversing gear can be engaged, and in each of these gears two shifting elements are closed and three shifting elements are open. To carry out a gearshift and thus to carry out a shifting process, at least one of the previously open shifting elements A2, B2, C2, D2, and E2 of the automatic transmission is closed or engaged and at least one of the previously closed shifting elements A2, B2, C2, D2, and E2 is opened or disengaged. The transmission layout shown in FIG. 3 is presented purely as an example. Besides frictional shifting elements, interlocking shifting elements can also be present.

[0047] FIG. 4 shows an example shifting scheme for the automatic transmission of FIG. 3. In each gear two of the shifting elements A2, B2, C2, D2, and E2 are closed and three of the shifting elements A2, B2, C2, D2, and E2 are open. The shifting elements are in the form of clutches A2, B2 and brakes C2, D2, and E2.

[0048] The first forward gear is obtained by closing the clutch A2 and the brake E2, the second forward gear by closing the clutch A2 and the brake D2, the third forward gear by closing the clutch A2 and the brake C2, the fourth forward gear by closing the clutches A2 and B2, the fifth forward gear by closing the clutch B2 and the brake C2, and the sixth forward gear by closing the clutch B2 and the brake D2. The reversing gear is obtained by closing the brakes C2 and E2.

[0049] According to the invention, with this embodiment too an undesired rolling condition of the vehicle caused by elevated drag losses in the vehicle transmission can be prevented. During a possible actuation of the multi-gear vehicle transmission, for example the following steps can be carried out: [0050] 1. The neutral gear of the vehicle transmission is called for, for example automatically, or by a driver who actuates the driving switch to the “Neutral” driving switch position. [0051] 2. When the neutral gear is called for, first of all a transmission condition of the vehicle transmission is determined. If the transmission is in a condition with elevated drag losses, then in addition to the shifting elements A2, E2 of a driving gear, and here again the first forward gear is considered as the said driving gear, at least one of the further shifting elements B2, C2, D2 of the vehicle transmission is actuated in the closing direction. By closing at least the clutch B2 or one of the two brakes C2, D2, the vehicle transmission is braced or blocked and in that way the motor vehicle is kept at a standstill. Preferably however, only the brake C2 of the vehicle transmission is additionally closed in order to bring about the bracing or blocking of the transmission. Then, three shifting elements A2, C2, E2 of the vehicle transmission are actuated, of which the shifting elements A2, E2 are shifting elements of the first gear and the shifting elements C2, E2 are shifting elements of the reversing gear. Thus, the brake E2 is closed both for the first gear and also for the reversing gear. [0052] 3. If thereafter the driver calls for the first gear as a starting gear, the shifting element C2 of the reversing gear is opened. Since the shifting elements A2, E2 of the first gear are already closed, by opening the brake C2 the first gear is engaged and the vehicle can drive forward immediately. [0053] 4. If instead of the first gear the driver calls for the reversing gear, then the shifting element A2 of the first gear is opened. Since the shifting elements C2, E2 of the reversing gear are already closed, the reversing gear is engaged by opening the clutch A2 and the vehicle can move off in reverse immediately. [0054] 5. If the operating temperature of the vehicle transmission has been reached before the driver calls for a driving gear, then the neutral gear is engaged in the vehicle transmission. If the vehicle transmission has reached its operating temperature, the drag losses of the vehicle transmission while the neutral gear is engaged are so low that the vehicle does not change to an undesired rolling condition.

[0055] By virtue of the method proposed an undesired rolling condition of the vehicle if the vehicle transmission is cold, i.e. with a transmission condition in which drag losses are elevated, can be reliably avoided.

TABLE-US-00001 Indexes 1 Transmission input 2 Transmission output 3 Shaft 4 Shaft 5 Shaft 6 Shaft 7 Shaft 8 Shaft 9 Shaft 10 Shaft 11 Gearset 12 Gearset 13 Gearset 14 Gearset 15 Transmission input 16 Transmission output 17 Shaft 18 Shaft 19 Shaft 20 Shaft 21 Shaft 22 Shaft 23 Gearset 24 Gearset 25 Gearset A Shifting element/Brake B Shifting element/Brake C Shifting element/Clutch D Shifting element/Clutch E Shifting element/Clutch A2 Shifting element/Clutch B2 Shifting element/Clutch C2 Shifting element/Brake D2 Shifting element/Brake E2 Shifting element/Brake