Patent ID: 8500596

Claim:
A vehicle drive force distributing apparatus comprising: an irreversible transmission mechanism configured to prevent a radially oriented pressing force, generated between a first roller and a second roller by an inter-roller radial pressing force generating source in response to an inter-roller radial pressing force command value, from decreasing during a period while the inter-roller radial pressing force command value is constant, such that the irreversible transmission mechanism maintains the radially oriented pressing force at a value prescribed by the inter-roller radial pressing force command value without operating the inter-roller radial pressing force generating source during the period while the inter-roller radial pressing force command value is constant, the first roller being mechanically coupled to a main drive wheel and the second roller being mechanically coupled to a subordinate drive wheel and configured to distribute a drive force to the subordinate drive wheel by frictionally contacting the first roller such that a drive force distribution between the main drive wheel and the subordinate drive wheel is based on the radially oriented pressing force; an operating state determining component configured to determine whether a first vehicle operating state exists during which a first precision level of drive force distribution control is to be performed between the main drive wheel and the subordinate drive wheel or a second vehicle operating state exists during which a second precision level of drive force distribution control, less than the first precision level, is to be performed between the main drive wheel and the subordinate drive wheel; and a command value resolution switching component configured to provide the inter-roller radial pressing force command value to the inter-roller radial pressing force generating source when the operating state determining component determines that the second vehicle operating state exists, such that the period while the inter-roller radial pressing force command value is constant is longer when the second vehicle operating state exists than when the operating state determining component determines that the first vehicle operating state condition exists.