Electromagnetically controlled seat valve

An automatic transmission for a motor vehicle, comprising an electromagnetically controlled seat valve that includes a hollow housing bounding a user channel having one end to be connected to a hydraulic medium user and another end, a respective supply and a discharge channels communicating with the interior of said housing between said end, and at other end of said user channel, respectively;

• a valve part connected with a magnet part and provided with a valve seat;
• a closing member cooperating with said valve sea and mounted in said housing for movement toward and away from a closing position in which it sealingly separates said user channel from said discharge channel;
• means in said housing at said other end of said user channel for applying a variable closing force to said closing member to urge the latter toward said closing position thereof, including an electrically energizable coil, an armature mounted between said coil and said closing member for relative movement in response to electromagnetic forces exerted by the latter when energized, and a return spring urging said armature in a direction corresponding to said closed position of said closing member;
• and throttling means interposed between said supply and user channels for determining the amount of the hydraulic medium supplied into said user channel and hence the force with which this medium acts on said closing member against said variable closing force to open said closing member and thus establish a pressure-relieving communication between said user and discharge channels, including at least two throttling orifices extending in fluid flow parallelism with one another between said supply and user channels and each having a length and a transverse dimension that are in a ratio of at least 2:1.