• Solenoid valve includes a housing defining a chamber

    Date: 2012-9-5 14:20:26

    Proportional variable bleed solenoid valve that includes magnetic force adjustments to provide magnetic calibration. The control valve includes a housing defining a chamber, where an electromagnetic coil is wound on a bobbin and is coaxially mounted within the housing.

    A movable armature is coaxially positioned within the bobbin in the chamber and has an armature poppet valve extending form a bottom end of the armature. An armature spring is in contact with an upper end of the armature and a top wall of the bobbin, where the spring positions the armature in an initial position when the coil is not energized and where the armature moves to a second position in conjunction with the bias of the armature spring when the coil is energized. A pole piece is mounted to the housing and is positioned adjacent to the lower end of the armature to define an air gap between the pole piece and the armature.

    The pole piece includes an extended annular ring positioned below the lower end of the armature such that the armature poppet valve extends through the ring. A mounting bracket is secured to the housing adjacent to the pole piece and a valve sleeve is connected to the mounting bracket. The valve sleeve includes a central bore axially aligned with the armature such that a bottom seal surface of the armature poppet valve seats against a valve seat surface of the valve when the coil is energized to seal off an exhaust port so that a supply pressure orifice connected to the valve sleeve provides a control pressure at a control pressure opening in the valve sleeve.

    In order to provide magnetic force adjustments for magnetic calibrations, the valve sleeve is selectively positionable relative to the bracket so that the distance between the armature poppet valve and the seat surface is adjustable. In one particular embodiment, the valve sleeve is secured to the bracket by a threaded connection so that its position can be readily changed.

    Most vehicles generally incorporate a large number of electronically controlled systems, such as an automatic transmission controller. Automatic transmission controllers typically include several solenoid operated fluid control valves that independently act to control fluid pressure in the vehicle¡¯s transmission to operate various components of the transmission. For example, solenoid operated fluid control valves are known that use transmission fluid pressure to engage and disengage the transmission clutch. One particular known solenoid valve used for this purpose is referred to as a proportional bleed solenoid valve. The proportional bleed solenoid valve provides a particular control pressure that is directly proportional to the current applied to the solenoid coil in the valve. In other words, the output control pressure is nearly linear to the current applied to the solenoid coil. These types of solenoid valves are referred to as bleed valves because they use a relatively low flow of fluid through the hydraulic portion of the valve. Solenoid operated fluid control valves are also used in other vehicle controllers besides transmission controllers.

    As the controllers become more sophisticated, it is necessary that the solenoid operated fluid control valves also include advancements and improvements over the state of the art. In this regard, it becomes important to increase the operating efficiency, reduce the cost, reduce the weight, reduce the complexity, etc. of the existing solenoid operated fluid control valves. Therefore, advancements in size, part reduction, component simplification, etc. of the control valves is advantageous.

    One area of improvement for proportional valves is providing a consistent control pressure. Because the component tolerances in the control valves may vary from valve to valve, the control pressure may also vary from valve to valve at the same coil current. This may be important for modern automatic transmission controllers that need to provide a consistent control pressure for a particular operation. Therefore, it is important to provide some kind of calibration of the valve at the manufacturing level of the valve so that the valve control is consistent. One area where the control pressure of a proportional solenoid valve can be calibrated is the magnetic force adjustment, where an armature position driven by the coil of the solenoid can be calibrated.

    Although the solenoid valve described in the 999 patent offers one technique for adjusting the air gap between the armature and the pole piece to provide magnetic calibration, this technique is also susceptible to the tolerances of the elastic washer, as well as including other disadvantages. Therefore, there is still room for improvement in solenoid valves to provide a magnetic force adjustment for magnetic calibration.

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