Motor vehicle drive train comprising a hydrodynamic retarder that can be disengaged, and control method therefor

Patent metadata

Field	Value
Publication number	US-9291220-B2
Application number	US-201214119106-A
Country	US
Kind code	B2
Filing date	Nov 28, 2012
Priority date	Dec 9, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A motor vehicle drive train including a hydrodynamic retarder ( 1 ) that comprises a revolving bladed impeller ( 10 ) and a stationary or counter-rotating bladed turbine ( 11 ) which jointly form a working chamber ( 12 ) that can be filled with a working medium to switch on the retarder ( 1 ) is disclosed. The hydrodynamic retarder ( 1 ) can be mechanically disengaged from the drive train by a disconnect clutch ( 2 ). A fill level monitoring device ( 14 ) can detect the current fill level of the working medium in the working chamber ( 12 ), while a disconnect clutch-blocking device ( 9 ) is effectively connected in a communicating or mechanical manner to the fill level monitoring device ( 14 ) and prevents the disconnect clutch ( 2 ) from engaging in accordance with the detected fill level.

First claim

The invention claimed is:

1. Motor vehicle drive train comprising:
a hydrodynamic retarder comprising a rotating bladed primary wheel and a bladed secondary wheel which is one of stationary and rotating in opposite direction to the primary wheel, which form together a working chamber which can be filled with a working medium to switch on the retarder, whereas
the hydrodynamic retarder can be disengaged mechanically from the drive train by means of a separating clutch,
a filling level monitoring device, which detects current filling level of the working medium in the working chamber and
a separating clutch blocking device, which is in one of communicating and mechanical operative connection with the filling level monitoring device and blocks the closing of the separating clutch according to the current filling level detected.

2. Motor vehicle drive train according to claim 1 , wherein the filling level monitoring device comprises one of a floater arranged in the working chamber of the retarder and a floater arranged in an auxiliary chamber communicating fluidly with the working chamber in respect of the current filling level of working medium.

3. Motor vehicle drive train according to claim 2 , wherein the filling level monitoring device comprises one of an electric, an optical and an acoustic sensor and an associated interpreting unit, by means of which the filling level of one of the working chamber and an auxiliary chamber of the retarder communicating fluidly with working chamber in respect of the current filling level is detected by one of an electric resistance measurement, an optic signal measurement and an acoustic signal measurement.

4. Motor vehicle drive train according to claim 2 , wherein a control device is one of associated to and integrated in one of the filling level monitoring device and the separating clutch blocking device, which one of detects, receives and calculates as an input variable a current rotational speed of a primary side of the separating clutch side facing away from the retarder and additionally controls the closing of the separating clutch as a function of the current rotational speed.

5. Motor vehicle drive train according to claim 1 , wherein the filling level monitoring device comprises one of an electric, an optical and an acoustic sensor and an associated interpreting unit, by means of which the filling level of one of the working chamber and an auxiliary chamber of the retarder communicating fluidly with working chamber in respect of the current filling level is detected by one of an electric resistance measurement, an optic signal measurement and an acoustic signal measurement.

6. Motor vehicle drive train according to claim 5 , wherein a control device is one of associated to and integrated in one of the filling level monitoring device and the separating clutch blocking device, which one of detects, receives and calculates as an input variable a current rotational speed of a primary side of the separating clutch side facing away from the retarder and additionally controls the closing of the separating clutch as a function of the current rotational speed.

7. Motor vehicle drive train according to claim 1 , wherein a control device is one of associated to and integrated in one of the filling level monitoring device and the separating clutch blocking device, which one of detects, receives and calculates as an input variable a current rotational speed of a primary side of the separating clutch side facing away from the retarder and additionally controls the closing of the separating clutch as a function of the current rotational speed.

8. Motor vehicle drive train according to claim 7 , wherein the control device one of: calculates a limit rotational speed related to the filling level; and stores one of a characteristic a limit rotational speed line and a characteristic limit rotational speed curve related to the filling level, and the control device blocks the closing of the separating clutch by means of the separating clutch blocking device in case of filling levels, when the corresponding current rotational speed lies above the corresponding limit rotational speed or characteristic limit rotational speed line.

9. Motor vehicle drive train according to claim 8 , wherein the control device has a retarder activation signal input to which a signal is applied, which signals an activation request for the retarder and the control device causes the blocking of the closing of the separating clutch in spite of the activation request, and after the blocking, as soon as a current rotational speed lies below one of: the limit rotational speed; and one of the characteristic limit rotational speed line and the characteristic limit rotational speed curve, initiates the closing of the separating clutch independent of another activation request.

10. Method for controlling a motor vehicle drive train having a hydrodynamic retarder which can be filled and emptied with a working medium, and which can be disengaged mechanically from the drive train by means of a separating clutch, comprising the following steps:
receiving a signal of an activation request for the retarder when the separating clutch is opened,
detecting a filling level of the working medium in a working chamber of the retarder, which working chamber is formed by a bladed primary wheel and a bladed secondary wheel, and
blocking the closing of the separating clutch according to the filling level detected.

11. Method according to claim 10 , further comprising the step of closing the separating clutch only when the working chamber has been emptied of working medium.

12. Method according to claim 10 , wherein the step of blocking the closing of the separating clutch according to the filling level detected comprises closing the separating clutch according to the filling level and to a current rotational speed of a primary side of the separating clutch, which primary side facing away from the retarder, whereby a closing takes place in the presence of comparatively small rotation speeds also with a working chamber filled with working medium and a closing takes place in the presence of comparatively larger rotational speeds only with an emptied working chamber.

13. Method according to claim 12 , further comprising providing one of a limit rotational speed and a characteristic limit rotation speed line, by means of which at least one maximal admissible filling level is associated to a rotational speed of the primary side of the separating clutch and the closing of the separating clutch is blocked when the current rotational speed of the primary side is above one of the limit rotational speed and the characteristic limit rotational speed lines and said closing is admitted below said values.

14. Method according to claim 13 , wherein, after the blocking of the closing of the separating clutch the method comprises the step of closing the separating clutch if the rotational speed of the primary side of the separating clutch falls to a current value below one of the limit rotational speed and the characteristic limit rotational speed line, also without an activation request for the retarder, to empty the retarder.

Assignees

• Voith Patent Gmbh

Inventors

• Menne Achim
• Huth Tilman
• Laukemann Dieter
• Koch Werner
• Klement Werner
• Becke Martin

Classifications

• F16D48/06

  Control by electric or electronic means, e.g. of fluid pressure · CPC title

• F16D67/02

  Clutch-brake combinations · CPC title

• B60T10/02

  with hydrodynamic brake · CPC title

• F16D57/04 Primary

  with blades causing a directed flow, e.g. Föttinger type · CPC title

• B60T1/087

  in hydrodynamic, i.e. non-positive displacement, retarders · CPC title