CVT transmission

Patent metadata

Field	Value
Publication number	US-10167936-B2
Application number	US-201415103258-A
Country	US
Kind code	B2
Filing date	Nov 28, 2014
Priority date	Dec 9, 2013
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A CVT transmission including a start-up element, a variator, and a direct-shift stage for switching between a first operating range (low) and a second operating range (high). A maximum transmission ratio of the second operating range (high) corresponds to a minimum transmission ratio of the first operating range (low). The transmission ratio ranges are arranged so that the marginal variator transmission ratio ranges, which constitute low-efficiency ranges, are not used.

First claim

What is claimed is:

1. A continuously variable transmission (CVT transmission) comprising:
a start-up element,
a variator, and
a direct-shift stage for switching between a first operating range and a second operating range,
wherein a maximum transmission ratio of the second operating range corresponds with a minimum transmission ratio of the first operating range, and
wherein a closing valve is operatively connected to a variator fluid system so that the variator fluid system is closed fluid-tight by the closing valve when the direct-shift stage is in operation, with the variator uncoupled, for propulsion.

2. The CVT transmission according to claim 1 , wherein a minimum variator transmission ratio of the second operating range is higher than a minimum variator transmission ratio of the first operating range.

3. The CVT transmission according to claim 1 , wherein a claw clutch is included in the direct-shift stage as a normally open clutch.

4. The CVT transmission according to claim 1 , wherein the direct-shift stage bridges the variator and is directly connected to an input drive.

5. The CVT transmission according to claim 1 , wherein a sub-transmission is positioned between the variator and a differential.

6. A method for operating a continuously variable transmission (CVT transmission), comprising:
using a start-up element as a control element against drive train locking when switching to a direct-shift stage configured for switching between a first operating range and a second operating range,
wherein a closing valve is operatively connected to a variator fluid system so that a variator fluid system is closed fluid-tight by the closing valve when the direct-shift stage is in operation, with a variator uncoupled, for propulsion.

7. The method according to claim 6 , wherein in a quick reset of a transmission ratio the system jumps directly from one operating range into the other operating range without using the direct-shift stage and without resetting completely steplessly.

8. The method according to claim 6 , further comprising utilizing the start-up element in a slipping mode to accelerate the variator, which is initially stationary, before the direct-shift stage is uncoupled and before power is routed to the variator.

9. The method of claim 6 , wherein a maximum transmission ratio of the second operating range corresponds with a minimum transmission ratio of the first operating range.

Assignees

• Schaeffler Technologies Ag

Inventors

• Walter Bernhard

Classifications

• F16H37/082

  and additional planetary reduction gears · CPC title

• F16H2200/0008

  specially adapted for front-wheel-driven vehicles · CPC title

• F16H3/54

  one of the central gears being internally toothed and the other externally toothed · CPC title

• F16H37/022 Primary

  the toothed gearing having orbital motion · CPC title

• F16H2200/0034

  the gear ratios comprising two forward speeds · CPC title