The present invention relates in general to solenoids and more specifically to solenoids used in conjunction with a valve to control operation of the valve.
Electromagnetically operated valves are known which include a bobbin supporting a winding formed as a coil of wire. A stationary core or pole plate typically made of a conductive material such as iron is mounted adjacent to a center hole of the bobbin. A movable armature is slidably disposed within the aperture of the bobbin such that when electrical current is passed through the winding of the coil, the armature is induced to translate toward the stationary pole plate. This translation of the armature can be mechanically used to actuate a valve assembly through the use of a pushpin in contact with the armature and which is also in contact with a valve assembly within the valve body. A biasing device is typically provided to return the valve assembly to its original position which also displaces the armature back to its de-energized location. An operating cycle of one of these electromagnetically operated valves is therefore the time from initial energizing of the coil to the time when the armature has returned to its original position.
When it is desirable to reduce the body size of the valve in order to maximize a quantity of valves for a particular operation, the winding of the coil is necessarily reduced in size, thereby reducing the attraction force between the armature and the pole plate and/or reducing the operating speed of the valve. To resolve this problem, solenoid geometry has changed such that the geometry of the coil is shaped substantially rectangular permitting an equal number of windings of the coil in a width of the solenoid commensurate with the necessary use. An example of a rectangularly shaped coil and its construction is provided in U.S. Pat. No. 6,698,713 issued to Sato et al. on Mar. 2, 2004. The patent to Sato et al. also identifies a known method to calculate the attraction force generated between an armature and a pole plate, and a power consumption.
The U.S. patent to Sato discloses a ratio of a length “A” of a longer axis or side of a solenoid inner coil to a length “B” of a shorter axis or side of the solenoid inner coil having a relationship expressed as: 1.3≦A/B≦3.0. The limited ratio range of Sato restricts the geometry of the solenoid and therefore can preclude a desired solenoid wattage and/or valve operating speed for narrow or tightly arranged solenoid/valve applications.
A rapid response solenoid for an electromagnetically operated valve according to a preferred embodiment of the present invention includes a bobbin having a substantially rectangular shaped cross section. A coil is wound around the bobbin. A stationary pole plate is fixed in relation to the bobbin. An armature is slidably disposed within the bobbin and slides toward the pole plate in response to a magnetic field generated by the coil through the pole plate. The armature has a substantially rectangular shape having a short axis side and a long axis side. A ratio of a length A of the long axis side of the armature to a length B of the short axis side of the armature has an operable range of 3.1≦(A/B)≦4.5.
According to another preferred embodiment of the present invention, the stationary pole plate is positioned at a bobbin first end having a portion of the pole plate extending within a through aperture formed in the bobbin. A bushing is disposed within the through aperture and substantially fixed in relation to the bobbin. The bushing is positioned between the armature and an inner wall of the bobbin and provides a sliding fit between the armature and the bobbin inner wall. A brass or other non-magnetic material used for bushing reduces friction and magnetic attraction of the armature to the bushing and therefore increases a de-energized return speed of a valve connected to the solenoid.
Advantages of the present invention include the capability of accepting higher operating wattages, a faster cycle time for an attached valve and a solenoid assembly less susceptible to wear from friction of the moving parts. A smaller wire size is also used which provides additional benefit to the solenoid operating force and power generated. By using the geometry for a solenoid of the present invention, an improved cycle time at a given solenoid size is also provided.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
According to a preferred embodiment of the present invention and referring generally to
Referring next to
Solenoid 12 is also provided with a cover 42 which seals solenoid 12 from the external environment. Cover 42 is connected to flux frame 30 by an adapter 44 and one or more fasteners 46. Within cover 42 is disposed a current distribution plate 48, which is in direct contact with a lead pin 50. Lead pin 50 is disposed within an insulating bushing 52 to electrically isolate lead pin 50 from cover 42. Electrical current provided to the windings of coil 32 is provided via lead pin 50 through current distribution plate 48 and a coil connector 54.
Armature 34 is positioned as shown in
Pushpin 58 directly contacts a first end of a valve member 60 provided within valve body 14. Valve member 60 is slidably disposed within valve body 14 such that valve member 60 is displaceable in each of the directions of arrows “X” and “Y”. In the solenoid de-energized position shown in
Referring generally now to
Providing the above range of the ratio of “A” to “B” for armature 34 permits maximizing a length “L” of coil 32 compared to coil width “W” such that a higher current and wattage can be used for coil 32. It is common in the industry for solenoid operated valves to use an actuation wattage of approximately four to five watts. Faster acting solenoids are available using approximately 16 watts of electrical power. A solenoid 12 of the present invention permits operation up to approximately 215 watts. This is accomplished by the geometry of coil 32 and armature 34 and in part through the use of smaller gauge wire within coil 32, ranging from approximately 33.5 to 35.5 gauge. Increasing the wattage for solenoid 12 provides a significantly faster acting valve assembly 10 because the higher wattage creates a greater magnetic flux in coil 32 which increases the travel speed of armature 34. Cycle time can be reduced from known 4 watt solenoid valve designs having cycle times of approximately 3 milliseconds to approximately 340 microseconds using a solenoid design according to the present invention.
A further improvement of the valve assembly 10 of the present invention is provided by the use of a non-magnetic material, and preferably a brass material, for bushing 36. A non-magnetic material used for bushing 36 and in particular a material such as brass provides a low coefficient of friction between armature 34 and bushing 36. In addition, the non-magnetic nature of bushing 36 reduces the likelihood-of magnetic attraction between armature 34 and bushing 36 during its return travel to the non-energized position shown in
Referring to
Advantages of the present invention include the capability of using higher operating wattages to achieve faster cycle times and/or increased solenoid driving force for solenoid actuated valves, and providing a solenoid assembly less susceptible to wear from friction of the moving parts. A smaller wire size is also used which further increases the solenoid operating force and power generated by the solenoid. By using the geometry for a solenoid of the present invention, an improved cycle time at a given solenoid size is also provided.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. For example, additional ports or ports oriented in a different configuration from those shown in
This application claims the benefit of U.S. Provisional Application Ser. No. 60/599,814 filed Aug. 6, 2004, the disclosure of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60599814 | Aug 2004 | US |