Drive device for a motor vehicle

Patent metadata

Field	Value
Publication number	US-10112599-B2
Application number	US-201515516974-A
Country	US
Kind code	B2
Filing date	Oct 1, 2015
Priority date	Oct 7, 2014
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A drive device for a motor vehicle, having an internal combustion engine that outputs to a gearbox or transmission. A plurality of gear ratios steps provides shiftable driving gears from a starting gear to a highest driving gear. The gearbox has at least one gear ratio step that provides an overrun gear, which cannot be engaged in the traction mode, but only in an overrun mode, in which the vehicle drags the internal combustion engine.

First claim

The invention claimed is:

1. A drive device for a motor vehicle, comprising:
an internal combustion engine that outputs to a gearbox or transmission having a plurality of gear ratio steps, wherein in a traction mode driven by the internal combustion engine, shiftable driving gears are provided, wherein from a starting gear to a highest driving gear, the gearbox has at least one gear ratio step that provides an overrun gear that cannot be engaged in the traction mode, but only in an overrun mode in which the vehicle drags the internal combustion engine.

2. The drive device according to claim 1 , wherein a magnitude of a drag torque (T Drag ) depends on a rotational speed of the internal combustion engine, wherein the smaller the rotational speed of the motor, the lower the drag torque (T Drag ), and wherein, for reduction of the drag torque (T Drag ), generated in the overrun mode, the overrun gear has a higher ratio than a highest driving gear that can be shifted in traction mode.

3. The drive device according to claim 2 , wherein, in the overrun mode with an engaged overrun gear, the rotational speed of the internal combustion engine can be lowered by a motor control unit down to an idling speed of the internal combustion engine.

4. The drive device according to claim 2 , wherein at least one or more than one gear ratio step that cannot be used as a driving gear, but can be used as the overrun gear, is shifted depending on a speed so the rotational speed of the internal combustion engine in the overrun mode can be lowered down to an idling rotational speed.

5. The drive device according to claim 1 , wherein a quotient of the ratio (i) of a driving gear that can be shifted in the traction mode to the ratio (i) of a next-higher driving gear that can be shifted in the traction mode defines a progressive ratio step (φ), wherein the gearbox is configured such that the progressive ratio step (φ) becomes smaller, the higher the driving gears.

6. The drive device according to claim 5 , wherein the progressive ratio step (φ) between the highest driving gear and the overrun gear is at least larger than a second progressive ratio step from the second-highest driving gear to the highest driving gear.

7. The drive device according to claim 1 , wherein the motor vehicle is a hybrid-driven motor vehicle with an electric motor as a second drive source, wherein the overrun gear can be engaged at least when the motor vehicle is braked via the electric motor in a recuperation operation.

8. The drive device according to claim 7 , wherein in the recuperation operation of the electric motor or in a braking operation of the motor vehicle, for at least one gear ratio step that is not provided as a driving gear, one or more transmission gear ratios are engaged such that, over a range of speeds, the rotational speed of the internal combustion engine is kept in an idling rotational speed range.

Assignees

• Audi Ag

Inventors

• Winkler Josef
• Vogtherr Karin
• Wansner Michael

Classifications

• F16H2061/0237

  Selecting ratios for providing engine braking · CPC title

• B60W30/18127

  Regenerative braking · CPC title

• B60Y2200/92

  Hybrid vehicles · CPC title

• B60W10/11

  Stepped gearings · CPC title

• F16H61/68

  specially adapted for stepped gearings · CPC title