1. Technical Field
The present invention generally pertains to motor vehicles. More particularly, the present invention pertains to a solenoid assembly for an automatic transmission of a motor vehicle.
2. Discussion
Generally speaking, motor vehicles require three basic components. These components include a power plant (such as an internal combustion engine), a power train, and wheels. The internal combustion engine produces force by the conversion of the chemical energy in a liquid fuel into the mechanical energy of motion (kinetic energy). The function of the power train is to transit this resultant force to the wheels to provide movement of the vehicle.
The power train's main component is typically referred to as the "transmission". Engine torque and speed are converted in the transmission in accordance with the tractive-power demand of the vehicle. The vehicle's transmission is also capable of controlling the direction of rotation being applied to the wheels, so that the vehicle may be driven both forward and backward.
Transmissions are generally referred to as manually actuated or automatic transmissions. Manual transmissions generally include mechanical mechanisms for coupling rotating gears to produce different ratio outputs to the drive wheels. Automatic transmissions are designed to take automatic control of the frictional units, gear ratio selection and gear shifting. A thorough description of an exemplary automatic transmission is set forth in commonly assigned U.S. Pat. No. 5,115,698, which is hereby incorporated by reference as if fully set forth herein.
A conventional automatic transmission includes frictional units which couple a rotational input member to one or more planetary gear sets. Other frictional units, typically referred to as brakes, hold members of the planetary gear set stationary during the flow of power. The drive clutch assemblies can couple the rotating input member of the transmission to the desired elements of the planetary gear sets, while the brakes hold elements of these gear sets stationary. The planetary gear sets provide for various ratios of torque and function to ensure that the available torque and the respective tractive power demand are matched to each other.
Modern electronic transmission control systems typically include a plurality of solenoid actuated valves for controlling hydraulic fluid pressures in response to particular transmission conditions. Each of the solenoids includes a terminal that, when energized, actuates a valve which applies or releases a friction element in response to a transmission controller, as is generally disclosed in commonly assigned U.S. Pat. No. 4,893,652, which is hereby incorporated by reference as if fully set forth herein.
While the transmission control systems heretofore employed, including but not limited to those described in U.S. Pat. Nos. 4,893,652 and 5,115,698 have desirable performance characteristics, there is still room for further improvement in the art.