System and method for inertial torque reaction management

Abstract

A system and method for managing inertial torque reactions on stationary powertrain structure rotate at least one selected engine component and at least one selected drive train component in opposite directions so the rotational inertia of the selected drive train component acts in a direction opposite to that of the rotational inertia of the selected engine component to reduce or eliminate the inertial torque reactions on stationary powertrain structure caused by rotational acceleration and deceleration of powertrain components and improves performance with respect to noise, vibration, and harshness (NVH).

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to systems and methods for managing inertial torque reaction of rotating machines. [0003] 2. Background Art [0004] A conventional powertrain has a “stationary” structure that is attached to the vehicle chassis with resilient mounts. In conventional powertrains, rotating inertia of various engine and transmission components including the crankshaft, flywheel, and torque converter of an automatic transmission, for example, is rotated in the same direction, having a compounding effect. When a compression or combustion event of the engine causes an acceleration of the rotating inertia, generally, there is an equal but opposite inertial torque reaction imposed upon the stationary structure. As such, the stationary structure is not truly stationary, but instead, vibrates in opposition to the accelerations of the rotating inertia. This vibration of the stationary structure passes vibration thr...

AI Technical Summary

Benefits of technology

[0007] The present invention includes a system and method for managing inertial torque reaction by rotating inertial powertrain or drivetrain components a direction opposite to the rotation of engine / motor inertial components, to reduce or eliminate torque reaction on stationary powertrain components.

[0009] In a transversely mounted internal combustion engine and transaxle, as generally used in, but not limited to, front wheel drive (FWD) vehicles, for example, the crankshaft and the torque converter may be connected using toothed wheels enabling the torque converter and crankshaft to rotate in opposite directions. A separate or integrated device may be used to reduce or eliminate backlash and associated noise, such as a scissors gear, for example. The opposing direction of rotation of the crankshaft and torque converter reduces or eliminates the inertial torque reaction on the stationary powertrain structure to reduce or eliminate unwanted vibration and noise.

[0010] A longitudinally mounted engine and transmission application, as generally used in, but not limited to, rear wheel drive (RWD) vehicles, for example, may incorporate a simple planetary gear set to connect the crankshaft to the torque converter. Such a planetary gear set typically includes a sun gear, a ring gear, and a carrier with a plurality of pinions that are constantly in mesh with the sun and ring gears. In such an arrangement, for example, the carrier may be rendered stationary by using a plurality of fasteners to connect it with the engine / motor block. The sun gear of the planetary gear set may be connected to the crankshaft using any of a variety of methods including using conventional fasteners or alternatively splines with at least one retaining ring. Likewise, the ring gear or the annulus of the planetary gear set may be connected to the engine / motor flex plate using a plurality of fasteners. Such an arrangement allows the ring gear to rotate in a direction opposite to that of the sun gear when the carrier is non-rotating. Thus, at least one drivetrain component, such as the torque converter, will rotate in a direction opposite to that of the crankshaft and create corresponding rotational inertia to reduce or eliminate the inertial torque reaction otherwise associated with a change in angular acceleration / deceleration of rotating components of the engine on the stationary powertrain structure reducing or eliminating associated noise and vibration.

[0011] The present invention provides a number of advantages. For example, the present invention provides systems and methods for managing inertial torque reaction by providing a counter-rotating inertia generated by conventional powertrain components to reduce or eliminate the torque reaction on the powertrain structure and improve performance with respect to noise, vibration, and harshness (NVH). Reversing rotation of conventional powertrain components obviates the need for additional components or mass to generate balancing inertia. This reduces any adverse impact on powertrain weight, responsiveness, and overall performance relative to conventional solutions that add components solely for balancing or canceling torque reactions associated with rotating inertia.

[0012] The present invention may allow variable displacement engines to idle and drive at low engine speeds with fewer than all of the cylinders firing without unacceptable NVH. Also, the reduced or limited inertial torque reaction on the stationary powertrain structure should reduce noise, vibration, and harshness (NVH) with the uneven firing intervals that occur when an 8-cylinder engine operates in a reduced or variable displacement mode with 3, 5, 6, or 7 firing cylinders, for example.

Problems solved by technology

This vibration of the stationary structure passes vibration through the resilient mounts into the vehicle chassis, and may result in unwanted noise and vibration within the vehicle passenger compartment.

However, the constraints placed on the engine / powertrain operation may impact the ability to achieve other desirable operating characteristics relative to responsiveness, fuel economy, and / or emissions, for example.

While these approaches may reduce the torque reaction on the powertrain structure, the increased mass also increases weight and reduces responsiveness of the system.

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