Patent Application
20070256747
Embodiments of the present disclosure relate generally to valves for pneumatic systems, and more particularly, to motor driven valves for pneumatic systems.
Pneumatic valves are commonly used in today's industrialized society. Typically, pneumatic valves are used to restrict fluid flow through a cavity, orifice, passageway, etc.
Often, pneumatic valves are operated by actuation of a solenoid. Although solenoids are convenient and well tailored to provide linear movement for reciprocating pneumatic valves, solenoids are not without their problems. For instance, solenoids are expensive and result in relatively expensive pneumatic valving systems. Therefore, although solenoid operated pneumatic valves are effective at restricting fluid flow through a cavity, orifice, passageway, etc., there exists a need for a more economical solution for achieving the same or similar result. Especially in situations requiring a larger orifice where speed of actuation is not critical.
A motor driven valve constructed in accordance with one embodiment of the present disclosure includes a casing having a valve bore and a valve slidably disposed in the valve bore. The valve is translatable from a first position to a second position. The motor driven valve also includes an inlet and an outlet interconnected by a cavity through which fluid may pass, and an electric motor for affecting movement of the valve from the first position to the second position.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
The casing 102 includes a main body portion 104 and an optional closure portion 106 removably connected to the motor 120 by suitable mechanical fasteners 108. The casing 102 is suitably formed of metal, thus creating a rigid and rugged housing for the internal components of the motor driven valve 100. However, it is contemplated that other materials, such as composite plastics or the like, may be utilized.
In the embodiment shown, the casing 102 defines a fluid inlet 110 and a fluid outlet 112 interconnected by a cavity 114 (see
As best shown in
The main body portion 104 further defines a pintle bore 118 disposed in parallel with the motor cavity 116. The pintle bore 118 extends from an upper surface of the main body portion 104 to the cavity 114 and is dimensioned to receive the pintle 142 of the pintle valve 140 in a slidably supporting manner, as will be described in more detail below.
In one embodiment, the motor 120 is a conventional brush or brushless, DC motor with a single rotational output shaft 126. However, any electrical motor, including either AC or DC having a rotational output shaft, may be utilized while remaining within the spirit and scope of the present disclosure.
The output shaft 126 of the motor 120 projects outwardly from the top of the main body portion 104. Contacts 130 are located at the opposite end of the motor 120 and are adapted to be connected to a power source. For example, the contacts 130 may be attached to a switch (not shown) in connection with a vehicle 12-volt battery terminal (not shown) in order to supply the motor 120 with appropriate power required to rotate the output shaft 126. The main body portion 104 of the casing 102 includes a contact aperture 132 near the contact end of the motor 120 to allow the contacts 130 to be connected to an external switch or battery, if desired.
Still referring to
In either embodiment, one end of the pintle 142 projects outwardly from the top of the main body portion 104 and mechanically engages with the transmission assembly 160, as described in more detail below. The opposite end of the pintle 142, to which the poppet 146 is mounted, is positioned within the cavity 114. The poppet 146 is configured to restrict fluid flow through the cavity 114 between the fluid inlet 110 and the fluid outlet 112 when placed in the proper position. In one embodiment, the poppet 146 is formed from a flexible material for improving its seal forming capabilities when contacting, for example, the opposing ends of the cavity 114.
In use, the poppet 146 reciprocates with the pintle 142 in order to create a valving function within the cavity 114, thus either permitting or restricting fluid flow communication between the fluid inlet 110 and the fluid outlet 112. In one embodiment, the poppet 146 is positioned to seal the fluid inlet 110 when the pintle valve 140 is in the closed position, as shown in
In one embodiment, a poppet seat 150 is provided for interaction with the poppet 146. The poppet seat 150 defines an aperture through its center for permitting fluid flow therethrough when the valve 140 is in the valve open position. The poppet seat 150 is suitably disposed in the fluid inlet 110 adjacent the cavity 114 and in alignment with the poppet 146.
In the valve closed position, the poppet 146 and the poppet seat 150 create a seal which substantially restricts the fluid flow from the fluid inlet 110 to the fluid outlet 112. In one embodiment, the poppet seat 150 has a lip on the surface which mates with the poppet 146 in the valve closed position in order to create a more effective seal with the poppet. The poppet seat 150 may be formed using any non-corrosive material which enables the poppet 146 to form a tight seal around the perimeter of the poppet seat 150.
As may be best seen by referring to
The drive gear 162 is mechanically coupled in a conventional manner to the driven gear 164, which is journaled for rotation on the main body portion 104. As such, the drive gear 162 provides rotational force to the driven gear 164 when the motor 120 is activated, thereby causing the driven gear 164 to rotate in a preselected direction from a first or starting position to a second or end position, as will be described in more detail below.
As best represented in
The cam 166 has a substantially consistent radial location with respect to the rotation axis of the driven gear 164. This allows the pintle valve 140, in its slidably mounted position perpendicular to the driven gear, to remain in contact with the cam 166 as the driven gear 164 rotates. As such, the end of the pintle valve 140 acts as a cam follower as the driven gear 164 is rotated and affects movement on the pintle valve 140.
In one embodiment, the cam 166 continues substantially around the driven gear 164, creating an arc slightly less than 360°. Alternatively, the cam 166 may form an arc which is only partially disposed around the driven gear 164, thus requiring the driven gear 164 to rotate fewer degrees to complete the cam's helical groove.
During operation of the motor driven valve 100, it may be desirable for the end of the pintle 142 to be in continuous contact with the cam 166. To that end, the pintle 142 may be biased against the cam 166 by a biasing device, such as a spring (not shown). The pintle valve 140 includes a pintle seal 170, which restricts fluid from entering the cavity 180.
The pintle seal 170 defines an aperture suitable dimensioned to facilitate the insertion of the pintle 142. The end of the pintle seal 170 adjacent to the cam 166 is coupled to the end region of pintle 142. The pintle seal 170 may be coupled to an annular groove formed on the pintle 142, whereby the pintle seal 170 is frictionally constrained to the pintle 142. Alternatively, the pintle seal 170 may be secured in a position relative to the pintle 142 by a collar on the pintle 142. The other end of the pintle seal 170 connected to the pintle guide 148 in a suitable groove. The pintle seal 110 may also include a bellows to facilitate elongation with minimal force.
In operation, the pintle seal 170 permits the pintle valve 140 to reciprocate between the valve closed and opened positions. Biasing members may be utilized to bias the pintle 142 against the cam 166 in order to maintain continuous contact between them, such as a coil spring, leaf spring, or the like.
Prior to activation of the motor 120, the driven gear 164 is in a first or starting position. As such, the pintle 142 is in contact with the shallowest part of the cam's helical groove, as depicted in
It will be appreciated that the stroke of the pintle valve 140 is the difference in the depth of the cam's groove in the activated and unactivated states and is substantially equal to the vertical displacement of the pintle 142. In one embodiment, the helical arrangement of the cam 166 provides a substantially constant slope. However, varying slopes may be beneficial to change the engagement speed of the pintle valve 140 when opening or closing the valve. In an alternative embodiment, the cam 166 may be a protruding structure from the bottom surface of the driven gear 164 rather than a groove. It will be appreciated that the protruding cam has the same helical configuration as the groove cam.
In alternative embodiments of the present disclosure, the transmission assembly may assume a plurality of different configurations in order to transmit the rotary motion of the output shaft 126 of the motor 120 into linear motion of the pintle valve 140. For example, the transmission assembly may be a piston which includes an arm linked to a rotary wheel coupled to the drive shaft of the motor, creating reciprocating motion. In another embodiment, the drive shaft of the motor may be directly coupled to a cam which translates the pintle valve in a linear manner.
In a further embodiment, a rack and pinion mechanism may be utilized to convert rotary motion of the motor to linear motion of the pintle valve. In such a configuration, a drive gear containing a plurality of teeth is coupled to the motor and acts as the pinion. A rack is in mechanical communication with the pinion by the meshing of teeth interacting with each other, providing reciprocating motion to the pintle valve. Alternatively, the pintle may be integrated with the rack in order to reduce parts and linkages. It will be appreciated that other transmission assemblies may be utilized to convert rotary motion into linear motion, such as a lead screw, while remaining within the scope and spirit of the present disclosure.
As earlier described, the driven gear 164 of the transmission assembly 160 attains first and second positions during the operation of the motor driven valve 100. In embodiments that utilize a unidirectional electric motor, it may be advantageous for one of the gears of the transmission assembly 160 to be biased against rotation when the motor 120 is activated. Therefore, in certain embodiments, the motor driven valve 100 includes a biasing device 168, such as a torsion spring, functionally connected to the driven gear 164 of the transmission assembly 140.
In use, when the motor 120 rotates the drive gear 162, the drive gear 162 in turn drives the driven gear 164 from the first position to the second position against the biasing action of the biasing device 168, thereby storing energy therein. When the motor 120 is deactivated, the biasing device 168, in this case, the torsion spring, unwinds, releasing the stored energy, and rotating the driven gear 164 back to the first position. As was described briefly above, the motor 120 affects movement of the pintle valve 140 from a valve closed position to a valve opened position, or vice versa, via a transmission assembly 160.
While the biasing device 168 is shown as a torsion spring, it is contemplated that other biasing means may be used to bias one or more components of the transmission assembly 160 into the first position without departing from the spirit and scope of the present disclosure. Additionally, while the driven gear 164 is shown biased against rotation, it will be appreciated that either the drive gear 162 or the driven gear 164 or both can be biased against rotation.
In some embodiments, it is desirable to utilize a biasing device 168 which will not overcome the motor 120 when the motor 120 is in the activated state, preventing the driven gear 164 from rotating fully to the second position. Therefore, the spring constant (K) of the biasing member should be selected so as to allow the motor 120 to overcome the biasing device, permitting full rotation of the driven gear 164 as necessary to complete the cam's helical curve. Conversely, the spring constant (K) should be selected so as to overcome friction resulting from the gears and motor so that the driven gear 164 may return to its first position when the motor 120 is deactivated.
Although several embodiments of the present disclosure include a biasing device 168 to return the driven gear 164 to the first position when the motor 120 is returned to a non-activated state, the absence of such a component does not depart from the present disclosure. Further, a reversible motor may be used. In such an example, the motor 120 may be activated in a first state to close the valve and then activated in a second state to open the valve. The first and second states may be achieved by reversing the contact wires utilizing a switching mechanism or be internally controlled by the reversible motor.
Operation of the motor driven valve 100 between the valve closed position and the valve opened position may be best understood by referring to
In order to close the motor driven valve 100 and thus substantially restrict fluid flow between the fluid inlet 110 to the fluid outlet 112, the motor 120 is deactivated. When deactivated, the biasing device 168 unwinds to rotate the driven gear 164, thereby releasing stored energy in the biasing member 168. As the driven gear 164 rotates, the pintle 142 traces the helical groove of the cam 166 from the deepest groove portion to the shallowest groove portion, slidably displacing the pintle 142 through the pintle bore 118, and thus translating the poppet 146 from the valve open position depicted in
As the pintle 142 traces along the helical groove on the cam 166, the pintle 142 reaches the end of the stroke where the poppet 146 is forced against the poppet seat 150, sealing the poppet seat aperture. In this position, the fluid inlet 110 is closed by the poppet 146 and fluid flow through the cavity 114 is substantially restricted. At substantially the same instant, the driven gear 164 and drive gear 162 stop rotating.
To return the motor driven valve 100 to the valve open position shown in
As the pintle 142 slidably translates, the poppet 146 disengages from the poppet seat 150, thus permitting fluid flow from the fluid inlet 110 to the fluid outlet 112. In this position, the poppet 146 is completely disengaged from the poppet seat 150, and thus, the motor driven valve 100 is in the valve open position. Fluid pressure forces the poppet 146 against the upper seat to seal the exhaust port (
Regarding the operation of the motor driven valve 100, the cycles may be altered to facilitate the same means of opening and closing a valve by actuating a motor, while still remaining within the sprit and scope of the present disclosure. For example, the activation of the motor may result in the driven gear moving the pintle 142 into a closed position. As a result, such embodiments are also within the scope of the present disclosure.
Preferably, the poppet 146 will seal the entrance to the exhaust outlet 196 when the motor driven valve 100 is in the valve open position, as depicted in
The exhaust outlet 196 may be equipped with a restricting mechanism, such as a one way valve, that restricts fluid flow to a single direction outward of the cavity 114 through the exhaust outlet 196, thus prohibiting foreign fluids or contaminates from entering the motor driven valve 100 through the exhaust outlet 196.
While several exemplary embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. For example, while the casing has been depicted as defining the inlet, outlet, and the cavity, it will be appreciated that such structure may be independent of the casing.
