Tau-omega armature-stator configuration of long stroke solenoid

An armature-stator structure (45) includes a stator (56) having a magnetic housing (57) of generally U-shaped cross-section. The housing includes an open end (58) in communication with an interior portion (60). A coil (94) is associated with the stator and to be energized to generate a magnetic field. An armature (46) has a generally ring-shaped base (48) and a generally rod-shaped stem portion (50) extending transversely from the base such that the base and stem portion define a generally T-shaped cross-section. The base is able to be received in the opened end of the housing with the stem portion extending into the interior portion. The armature moves with respect to the stator from a first position to a second position in response to the generated magnetic field. The stator and armature are configured such that a force on the armature decreases as a portion of the armature moves further into the interior portion of the body of the stator, towards the second position.

FIELD

The embodiment relates to a solenoid device and, more particularly, to the configuration of the armature and stator poles of the solenoid device.

BACKGROUND

Automotive applications typically using an air pump, specifically a turbine, supercharger or exhaust driven turbocharger, include gasoline, natural gas or diesel internal combustion engines, benefit from the use of an air bypass valve. Other automotive applications also include fuel cells and fuel reformers, both requiring large volumes of air, and often supplied by a turbine pump and benefit from an air bypass valve. These bypass valves include a solenoid device that has armature and stator poles.FIGS. 1A to 1Lshow some conventional shapes for basic magnetic cores. For example, the core10ofFIG. 1Ais a rod or cylindrical core, the core12ofFIG. 1Bis an E-core, the core14ofFIG. 1Cis a bar or I-core, the core16ofFIG. 1Dis a toroid or doughnut core, the core18ofFIG. 1Eis a C or U-core, the core20ofFIG. 1Fis a planar core, the core22ofFIGS. 1G and 1His a RM core, the core24ofFIGS. 1L and 1Jis a P core, and the core26ofFIGS. 1K and 1Lis an EDT core.

Combinations of core shapes create the various prior art solenoid configurations, such as E-E, EI, C-C, UI, EP, EEM, ER, and ETD. Armature-stator configurations can either be extrusions of the two dimensional representative shape or axis-symmetric revolutions around an axis.FIGS. 2A to 2Dshow some conventional armature-stator shapes. In particular,FIG. 2Ashows an armature30and a stator32with a central working gap,FIG. 2Bshows an armature34and a stator36with conical profile poles,FIG. 2Cshows an armature38and a stator40with a ⅔ located working gap, andFIG. 2Dshows an armature42and a stator44with a ⅓ located working gap. Although these configurations are useful, there can be improvements in the armature-stator configuration.

Thus, there is a need to provide an improved configuration of armature and stator pole configurations in a solenoid device such that the geometries of the armature and stator poles can be adjusted to various forces as a function of stroke characteristics.

SUMMARY

An object of the present invention is to fulfill the need referred to above. In accordance with the principles of an embodiment, this objective is obtained by providing a solenoid device having a stator assembly including a stator having a generally cylindrical magnetic housing of generally U-shaped cross-section. The housing includes an open end in communication with a hollow, interior portion. The stator assembly also includes a coil, associated with the stator, that is constructed and arranged to be energized to generate a magnetic field. An armature has a generally ring-shaped base and a generally rod-shaped stem portion extending transversely from the base such that the base and stem portion define a generally T-shaped cross-section. The base is able to be received in the open end of the housing with the stem portion extending into the interior portion. The armature is constructed and arranged to move with respect to the stator assembly between a closed position and an open position in response to the generated magnetic field. A spring biases the armature to the closed position. The stator and armature are constructed and arranged such that a force on the armature decreases as a portion of the armature moves further into the interior portion of the body of the stator, towards the open position thereof.

In accordance with another aspect of the embodiment, an armature-stator structure for a solenoid device includes a stator assembly including a stator having a generally cylindrical magnetic housing of generally U-shaped cross-section. The housing includes an open end in communication with a hollow, interior portion. The stator assembly also includes a coil, associated with the stator, that is constructed and arranged to be energized to generate a magnetic field. An armature has a generally ring-shaped base and a generally rod-shaped stem portion extending transversely from the base such that the base and stem portion define a generally T-shaped cross-section. The base is able to be received in the open end of the housing with the stem portion extending into the interior portion. The armature is constructed and arranged to move with respect to the stator from a first position to a second position in response to the generated magnetic field. The stator and armature are constructed and arranged such that a force on the armature decreases as a portion of the armature moves further into the interior portion of the body of the stator, towards the second position thereof.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Referring toFIGS. 3A to 3D, various embodiments of armature-stator structures, generally indicated at45, are shown. As shown inFIGS. 3A-3C, each armature46is of generally “Tau” or T-shaped in section having a generally ring-shaped base48and a rod-shaped stem portion50extending generally transversely with respect to the base48. With reference toFIG. 3D, the armature46′ is also of generally “Tau” or T-shaped, having a base48′ and a stem portion50′ extending generally transversely with respect to the base48′, but the base48includes chamfers52at ends thereof and the distal end of the stem portion includes a notch54therein.

As shown inFIGS. 3A-3C, each stator56includes a generally magnetic housing57of generally “Omega” or U-shaped in section. The housing57has an open end58that is sized to receive the base48,48′ of the armature46,46′ therein. The housing57has a hollow, interior portion60, in communication with the opened end58, that receives at least a portion of the stem portion50,50′ of the associated armature46,46′. In the embodiments ofFIGS. 3A,3B, and3D, the distal end of the housing57includes a flange62,62′ extending into the interior portion60. The distal end and the flanges62′ ofFIG. 3Dinclude a chamfer64. Each stator56also includes a guide portion66that receives and guides the distal end of the movable armature46. The guide portion66can be closed (FIG. 3A,3D) or open (FIG. 3B,3C).

FIG. 4is a graph of force on the armature46versus armature travel. Zero travel distance is the open position of the armature46(seeFIG. 6) and the 5.0 mm travel distance is the closed position of the armature (seeFIG. 5). The graph shows that the force actually decreases as the armature46moves into the stator56, and this is the opposite of what happens with the conventional configurations ofFIGS. 2A to 2D. Additionally, the negative force in the graph shows that if the armature46over-travels the target position, a force will act in the opposite direction to bring it to the target position and to a neutral force. This is advantageous because the armature46will come to rest due to the decrease of magnetic force and not due to a physical stop, thereby eliminating the need for a physical stop and the associated wear, impact and noise.

With reference toFIGS. 5 and 6, a solenoid device, in the form of an air bypass valve for a vehicle, is shown generally indicated at68, that employs the armature-stator structure45of an embodiment. While an air bypass valve is disclosed as the solenoid device68, other long stroke solenoid applications can benefit from the Tau-Omega armature-stator structure45disclosed.

The device68includes an armature and seal assembly, generally indicated at70. The armature and seal assembly70is the moving component of the device68and includes the armature46and a composite, resin or polymer molded pivot gland structure72either molded onto the base48of the armature46or assembled thereto with a mechanical retainer (not shown). Thus, the gland structure72can be considered to be part of the armature46. The gland structure72includes a gland member74, the function of which will be explained below. A dynamic seal76of an appropriate material is either incorporated as part of the gland structure72, co-injection molded therewith, or coupled thereto as a separate component. The dynamic seal76reduces air leakage past the armature46, reducing both air noise and bypass leakage. Finally, a hard seal structure78, preferably made of similar materials as the gland structure72, has a pivot member80that is preferably snapped together with the gland member74. The mating co-centric spherical surfaces (external surface82of gland member74and internal surface84of the pivot member80) form a pivot function such that the seal structure78can pivot with respect to the gland structure72. The 360° pivot function accommodates any dimensional variance from ideal between the axis of a stator assembly86, mounting face of the complete assembly, and the sealing surface and mounting surfaces of the respective air manifold component to which the device68is attached. By accommodating these variances, bypass leak is minimized and durable function of the solenoid maximized in allowing the hard sealing edge88of the seal structure78to mate with the opposite mounting sealing surface as parallel as possible. It is noted that the inner spherical surface84can be part of the gland member74with the outer spherical surface82being part of the pivot member80.

The stator assembly, generally indicated at86, includes the stationary magnetic components of the device68and comprises the magnetic (e.g., ferrous) housing57that provides a flux return path and a datum enclosure for other parts of the device68. A coil bobbin92is wound with an electromagnet coil94of a suitable wire material of an appropriate number of turns to provide the resistance and ampere-turns necessary for proper function with the available control electronics. The coil bobbin92with coil94is inserted into the housing57, and a magnetic (e.g., ferrous) flux ring96is pressed into the housing57, retaining the coil bobbin92and providing a specific working magnetic pole-type to the armature46. A spring pin98is received in a bore100in the stem portion50of the armature46so that a first end102of the spring pin98engages a spring104and a second end106of the spring pin98is adjacent to a magnetic end cap108such that the spring pin98and end cap108retain the spring104. The spring pin104provides an axial flux path into the armature46as well as guides the closing return spring104, also in bore100, in the final assembly. The Omega stator56comprises the lump magnetic circuit formed by the magnetic flux ring96, the magnetic housing57, the magnetic end cap108and, if desired, the spring pin98. Magnetomotive force for the functioning of the armature-stator structure45is provided by the energized coil94.

As shown inFIGS. 5 and 6, the stator assembly86is over-molded with an appropriate polymer or resin to provide the final encapsulation and retention main housing110of all stationary parts for the device68. The main housing110provides a customer specified flange (not shown) for mounting by the end user. In addition, the main housing110includes impact protection structure that protects the armature and seal assembly70from drops and handling, as well as any manifold sealing O-rings. In the embodiment, the impact protection structure includes a plurality of tabs112extending in an annular manner at an end of the housing57so as to generally surround the seal structure78of the armature and seal assembly70.

In the final assembly steps, the closing return spring104is inserted into the armature46, and the armature and seal assembly70is the inserted into the stator assembly86. More particularly, the stem portion50of the armature46is received in a bore114in the coil bobbin92. An O-ring116provides a seal with respect to an air manifold (not shown) to which the device68is attached.

Basic operation of the device68will be appreciated with reference toFIGS. 5 and 6.FIG. 5shows the closed position the device68and armature46(biased by spring104) when the electromagnetic coil94is not energized via leads118. In this position, the magnetic gap working area120is clearly shown and the sealing edge88is an extended position so as to engage with the manifold surface (not shown).FIG. 6shows the open position of the device68and armature46when voltage is applied to the coil94such that a force on the armature46overcomes the force of spring104. In this position, the sealing edge88is a retracted position so as to disengage with the manifold surface (not shown).

Thus, the device68is an electronically activated electromagnetic valve whose purpose is to bypass working air from the high pressure side to the low pressure side of a manifold pressure boost pump, turbocharger, supercharger, turbine air pump or similar. The valve68utilizes a novel passive internal pressure balancing method, reducing the noise of operation and reducing the force required to both open and close the valve. The air bypass valve68provides the functionality for the success, long term operation and efficiency of air boost systems, which depend on responsiveness to dynamic changes and robustness of operation.

The Tau-Omega armature-stator structure45allows for characteristics ranging from maximum force at maximum distance and minimum force at minimum distance, to essentially constant force versus distance characteristic, to be incorporated in electromagnetic solenoid devices by changing the geometries of the armature-stator interaction.