DRIVE TRAIN
A drive train including an internal combustion engine having a predefined number of cylinders, and operable in a first engine operating state in which all cylinders are in operation, and a second operating state in which some of the cylinders are not in operation. The drive train has a torsional-vibration damping system with at least one torsional-vibration damper and at least one centrifugal-force pendulum. In order to improve the torsional-vibration behavior of the drive train, a centrifugal-force pendulum and optionally a torsional-vibration damper are adapted to control torsional-vibration behavior of the engine in one operating state, and a torsional-vibration damper and optionally a second centrifugal-force pendulum are adapted to control the torsional-vibration behavior of the engine in the other engine operating state.
Latest Schaeffler Technologies GmbH & Co. KG Patents:
- Camshaft adjuster and separating sleeve for a camshaft adjuster
- TORSIONAL-VIBRATION DAMPING SYSTEM FOR A VEHICLE DRIVE TRAIN
- Method for producing a tribologically distressed laminate, a laminate and use of an organometallic compound for producing a functional layer of the laminate
- Roller for a pendulum mass of a centrifugal force pendulum
- Electric axle with a two gear transmission
This application is the U.S. national phase application under 35 U.S.C. §371 of International Application Serial No. PCT/DE2012/001129, having an international filing date of 26 Nov. 2012, and designating the United States, the entire contents of which are hereby incorporated by reference to the same extent as if fully rewritten.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a drive train including an internal combustion engine with a predefined number of cylinders, with a first operating state in which all cylinders are in operation, a second operating state in which some of the cylinders are switched off, and including a torsional-vibration damping system with at least one torsional-vibration damper and at least one centrifugal pendulum.
2. Description of the Related Art
Drive trains of this general type are typically used in motor vehicles. They include an internal combustion engine, a transmission, and a drive for driving the motor vehicle. Torsional-vibration damping systems that include one or more torsional-vibration dampers, for instance, are known in the art for isolating and damping torsional vibration of the internal combustion engine. The torsional-vibration dampers are preferably arranged on the crankshaft, or on a transmission input shaft of the transmission, and can be divided flywheels, torsional-vibration dampers in clutch discs of a friction clutch arranged between the crankshaft and the transmission input shaft and the like, and are known, for example, from the documents DE 37 03 123 A1 and DE 34 42 705 A1. Furthermore centrifugal pendulums have become known in the art as torsional vibration dampers, for example from the document DE 10 2010 005 599 A1. These centrifugal pendulums form a rotary-speed adaptive torsional-vibration damper by means of pendulum masses that may pivot to a limited extent relative to a pendulum flange received with the crankshaft or transmission input shaft. Moreover, combinations of centrifugal pendulums and the aforementioned torsional-vibration dampers are known, for example, from WO 2011/110153 A1, DE 10 2010 018 941 A1, and DE 10 2010 022 252 A1. The torsional-vibration damping system is adapted to the torsional-vibration behavior of the internal combustion engine, for example to the vibration order thereof. For four-stroke engines with four cylinders the vibration orders equal two and for four-stroke engines with two cylinders, the vibration orders equal one, for example.
DE 100 36 720 A1, for instance, discloses an internal combustion engine wherein a predefined number of cylinders can be switched off to save energy in driving situations that have low load requirements, and can be switched back on when a corresponding torque is required. The result is an internal combustion engine with two modes of operation in one drive train with different vibration orders, and thus different torsional-vibration behavior.
An object of the present invention is to provide a drive train that achieves an improved torsional-vibration behavior in both operating states of the internal combustion engine as a result of an adaptable torsional-vibration system.
SUMMARY OF THE INVENTIONThe object is attained by a drive train including an internal combustion engine with a predefined number of cylinders, with a first operating state in which all cylinders are in operation, and a second operating state in which some of the cylinders are switched off. The drive train further includes a torsional-vibration damping system with at least one torsional-vibration damper and at least one centrifugal pendulum, wherein a centrifugal pendulum and optionally a torsional-vibration damper are adapted to the torsional-vibration behavior of one operating state, and a torsional-vibration damper and optionally a second centrifugal pendulum are adapted to the torsional-vibration behavior of the other operating state. The use of multiple components of the torsional-vibration damping system in the form of at least one centrifugal pendulum and at least one torsional-vibration damper can improve the torsional-vibration behavior of the two operating states of the internal combustion engine selectively for each operating state. One or more components can be associated with each operating state.
One or more torsional-vibration dampers can be embodied as a divided flywheel with a spring device that is arranged between a primary inertial mass associated with the crankshaft, and a secondary inertial mass associated with a transmission input shaft of a transmission, and is arranged to be effective in the circumferential direction and has at least one damper stage. One or more torsional-vibration dampers can be embodied as a torsional-vibration damper with at least one damper stage in a clutch disc of a friction clutch that is arranged between the internal combustion engine and a transmission in the drive train, or as a similar system. If multiple damper stages are provided in a torsional-vibration damper, one damper stage can be associated with one operating state and the other damper stage can be associated with the other operating state and can be adapted to improve the torsional-vibration behavior thereof. For this purpose, the stiffnesses of the damper stages in the circumferential direction and rotation angles between the input and output parts of the torsional-vibration dampers are adapted in a corresponding way. In this context, higher degrees of stiffness are particularly advantageous for the damping and transmission of higher torques at comparatively small rotation angles, and lower degrees of stiffness are particularly advantageous for the compensation of vibrations at lower torques and larger rotation angles. The damper stages of lower stiffness are preferably by-passed at higher torques to protect them. The spring device can be formed of arc springs and/or coil springs. It is preferred that in one damper stage of a divided flywheel arc springs be provided, and otherwise helical compression springs be provided.
One or more centrifugal pendulums can be arranged at different locations of the drive train. It can be advantageous to adapt a single centrifugal pendulum to different orders of vibration, for example by providing pendulum masses of different vibration behaviors in that the pendulum masses include masses and/or vibration angles adapted to a respective order of vibration. A respective centrifugal pendulum can be arranged on the primary or secondary inertial mass of a torsional-vibration damper and/or on a torsional-vibration damper in a clutch disc, or on a friction clutch arranged between the crankshaft and the transmission input shaft in the drive train.
The invention will be explained in more detail below based on the exemplary embodiments shown in
Due to the fact that cylinders are switched off, a lower torque is applied to the torsional-vibration damping system 12 in the second operating state, so that the torsional-vibration behavior can be improved by means of the first, softer damper stage having the spring rate c1. The second torsional-vibration damper 19 can selectively or overall be associated with one operating state.
In a corresponding way,
As is apparent from graph 521 of
Claims
1: A drive train comprising:
- an internal combustion engine having a predefined number of cylinders and operable in a first engine operating state in which all the cylinders are in operation, and operable in a second engine operating state in which some of the cylinders are not in operation,
- a torsional-vibration damping system including at least one torsional-vibration damper and at least one centrifugal pendulum, wherein at least one of a centrifugal pendulum and a torsional-vibration damper is adapted to a control engine torsional-vibration behavior during the first engine operating state, and at least one of a torsional-vibration damper and a second centrifugal pendulum is adapted to control engine torsional-vibration behavior during the second engine operating state.
2: The drive train in accordance with claim 1, wherein a first torsional-vibration damper is a divided flywheel having at least one damper stage, and a second torsional-vibration damper is a torsional-vibration damper in a clutch disc having at least one damper stage of a friction clutch arranged between the internal combustion engine and a transmission in the drive train.
3: The drive train in accordance with claim 2, wherein a centrifugal pendulum is arranged on at least one of a primary inertial mass and a secondary inertial mass of the first torsional-vibration damper.
4: The drive train in accordance with claim 2, wherein a centrifugal pendulum is arranged on the second torsional-vibration damper.
5: The drive train in accordance with claim 3, wherein a centrifugal pendulum is arranged on at least one of a primary inertial mass and a secondary inertial mass of the first torsional-vibration damper, and the first torsional-vibration damper operates to control engine torsional-vibration behavior during the first engine operating state, and the first torsional-vibration damper operates to control engine torsional-vibration behavior during the second engine operating state.
6: The drive train in accordance with claim 3, wherein the first torsional-vibration damper operates to control engine torsional-vibration behavior during the first engine operating state, and a centrifugal pendulum arranged on at least one of a primary inertial mass and a secondary inertial mass of the first torsional-vibration damper, and the first torsional-vibration damper operate to control engine torsional-vibration behavior during the second engine operating state.
7: The drive train in accordance with claim 4, wherein the centrifugal pendulum arranged on the second torsional-vibration damper and a first damper stage of high stiffness operate to control the torsional-vibration behavior of the engine during the first operating state, and a second damper stage of low stiffness of the first torsional-vibration damper operates to control the torsional-vibration behavior of the engine during the second engine operating state.
8: The drive train in accordance with claim 4, wherein a centrifugal pendulum arranged on a secondary inertial mass of the first torsional-vibration damper operates to control the torsional-vibration behavior of the engine during the first engine operating state, and a centrifugal pendulum arranged on the second torsional-vibration damper operates to control the torsional-vibration behavior of the engine during the second engine operating state.
9: The drive train in accordance with claim 8, including a damper stage of high stiffness of the first torsional-vibration damper (615) is adapted that operates to control the torsional-vibration behavior of the engine during the second engine operating state.
10: The drive train in accordance with claim 8, including a damper stage of low stiffness of the first torsional-vibration damper operates to control the torsional-vibration behavior of the engine during the second engine operating state.
11: The drive train in claim 4, wherein the centrifugal pendulum arranged on the second torsional-vibration damper (519, 619) is adapted operates to control the torsional-vibration behavior of the engine during the first operating state, and a centrifugal pendulum arranged on a secondary inertial mass of the first torsional-vibration damper operates to control the torsional-vibration behavior of the engine during the second engine operating state.
Type: Application
Filed: Nov 26, 2012
Publication Date: Oct 9, 2014
Applicant: Schaeffler Technologies GmbH & Co. KG (Herzogenaurach)
Inventors: Hartmut Mende (Buhl), Walter Hepperle (Offenburg), Roland Seebacher (Neuried-Ichenheim)
Application Number: 14/362,852
International Classification: F16F 15/14 (20060101); F16F 15/129 (20060101);