Utility vehicle having a drive motor and a shifting claw transmission with an electric motor

• US 20090107270A1
• Filed: 03/13/2008
• Published: 04/30/2009
• Est. Priority Date: 09/14/2005
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler AG (Mercedes-Benz Group AG)
• Inventors: Sager, Frank, Krieger, Karl-Ludwig
• Granted Patent: US 7,992,458 B2
• Time in Patent Office: Days
• US Class Current: 74/339
• CPC Class Codes: F16H 2061/0422 by an electric machine, e.g. by accelerating or braking the input shaft
• CPC Class Codes: F16H 3/126 using an electric drive
• CPC Class Codes: F16H 59/38 of gearing elements
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: F16H 61/702 using electric or electrohydraulic control means
• CPC Class Codes: Y10T 74/1926 Speed responsive
• CPC Class Codes: Y10T 74/19284 Meshing assisters

Abstract

In a motor vehicle, in particular a utility vehicle, having a shifting claw transmission and an electric motor connected to a countershaft of the transmission to facilitate central synchronization for gear speed changes, a transmission controller is connected to the electric motor for sensing the electric motor speed and, together therewith the rotational speed of the countershaft based on the induction values present in at the electric motor and sensed by the transmission controller for use in adjusting the energization of the electric motor.

Claims

1. A motor vehicle, in particular a utility vehicle, having a drive motor (14), a shifting claw transmission (19) and an electric motor (M) which cannot operate the motor vehicle alone but which can be operatively connected to a countershaft (22) and can be actuated by a transmission controller (49) in order to synchronize the gear speed changes centrally, said transmission controller (49) including sensing means for determining the rotational speed of the countershaft on the basis of induction values in the electric motor (M).

2. The motor vehicle as claimed in claim 1, wherein the electric motor (M) is arranged coaxially with respect to the countershaft (22).

3. The motor vehicle as claimed in claim 1, wherein the electric motor (M) is a power converter-controlled squirrel cage asynchronous motor.

4. The motor vehicle as claimed in claim 2, wherein the electric motor (M) is directly connected to the countershaft (22) for rotation therewith.

5. The motor vehicle as claimed in claim 1, wherein the drive motor (14) of the motor vehicle is a diesel engine, and the motor vehicle has a group transmission with more than six forward gears, said group transmission comprising a split group (17) with at least two input constants and one main group (18).

6. The motor vehicle as claimed in claim 5, wherein the group transmission comprises a transmission output-end range group.

7. A method of shifting a motor vehicle having a drive motor (14), a shifting claw transmission (19) and an electric motor (M) which cannot operate the motor vehicle alone but which can be operatively connected to a countershaft (22) and can be actuated by a transmission controller (49) in order to synchronize the gear speed changes centrally, said transmission controller (49) including sensing means for determining the rotational speed of the countershaft on the basis of induction values in the electric motor (M), said method comprising the steps of:

during standstill of the vehicle, accelerating the countershaft (22) before or during engagement of a shifting element by means of the electric motor (M) in order to avoid a tooth-on-tooth or claw-on claw position between gear structures to be shifted into engagement with a freely rotating wheel and the shifting claw arrangement of a sliding sleeve, and, when there is a timing overlap, a clutch which is arranged in the force flux between the drive motor (12) and the shifting claw transmission is at least partially opened.

8. The shifting method for a motor vehicle as claimed in claim 7, wherein said clutch is a starter clutch (12).

9. The shifting method for a motor vehicle as claimed in claim 7, wherein said clutch is a shifting element of a split group (17) and is moved into a neutral position for disengaging a gear.

10. The shifting method for a motor vehicle as claimed in claim 7, wherein the electric motor is operated as a generator for braking the countershaft (22).

11. The shifting method for a motor vehicle as claimed in claim 7, wherein for braking the countershaft (22) the electric motor is actively energized in the rotational direction which is opposed to the direction of rotation of the countershaft.

12. The shifting method for a motor vehicle as claimed in claim 7, wherein the electric motor is regulated for rapidly bringing the countershaft to a particular desired speed facilitating smooth shifting of the claw transmission into or out of a particular gear.