The present invention relates to a coupling connecting an article handler to a source of pneumatic signals, and particularly to a rotary coupling for selectively blocking and restoring fluid communication between a rotating article handler and the stationary pneumatic signal source. More particularly, the present invention relates to a rotary coupling that couples a rotating article handler associated with a heat seal machine to the stationary source of pneumatic signals and that controls the communication of the pneumatic signals therebetween.
Food processing equipment is frequently complex equipment having various translating or rotating moving parts. In addition, food processing equipment can employ pneumatic flow such as vacuum or forced air to either hold an article against an article handler or to separate the article from the article handler. What is needed is a rotary coupling that can couple a stationary source of pneumatic signals to a rotating portion of an article handler to allow fluid communication therebetween. Equipment manufacturers and operators of food processing equipment would appreciate food processing equipment having such a rotary coupling that is capable of communicating pneumatic flow through multiple channels and conduits, that is capable of restricting the communication of the pneumatic flow so that the pneumatic flow is available only during selected portions of the rotation cycle of the article handler, and that is capable of communicating both vacuum and forced air signals.
According to the present invention, a rotary coupling is provided. The rotary coupling controls the communication of pneumatic signals from a stationary pneumatic signal source to an apparatus. The rotary coupling comprises a housing having an inlet in fluid communication with the pneumatic signal source and a rotating portion received in the housing for rotation with respect thereto. The rotating portion has an outlet in fluid communication with the apparatus. The inlet and the outlet are radially aligned relative to an axis of rotation of the rotating portion so that the inlet and the outlet are in fluid communication when the rotating portion is at an angular orientation at which the inlet and the outlet are coincident.
In preferred embodiments, the rotary coupling connects a rotating article handler associated, for example, with a heat seal machine to the source of pneumatic signals. The pneumatic signal source can illustratively include a vacuum source or a source of pressurized air. A rotating shaft, including a conduit in fluid communication with both the article handler and the rotary coupling, rotates the article handler. As the shaft rotates, the rotating article handler alternately lifts articles using suction force when the rotary coupling connects the article handler to the vacuum source and releases the articles when the rotary coupling removes the suction by disconnecting the article handler from the vacuum source and connecting the article handle to the source of pressurized air.
The rotary coupling in accordance with the present invention controls and "programs" the communication of pneumatic signals from the pneumatic signal source to the article handler. The rotary coupling establishes the sequencing of the pneumatic signals as well as the timing and duration of the signals. As the shaft rotates, the coupling selectively blocks and restores fluid communication between the article handler and the pneumatic signal source to communicate the pre-programmed pneumatic signals at each portion of the rotation cycle of the article handler. In addition, the coupling can be readily and easily adjusted to retard or advance the timing of the pneumatic signals. Also, the sequencing of signals can be changed entirely simply by changing a stationary pad inside of the coupling, completely "reprogramming" the sequence of pneumatic signals.
The rotary coupling includes a housing defining a cavity. The housing includes an end cap and the stationary pad which is supported by the end cap inside the cavity in a radially fixed orientation relative to the end cap for slight axial movement relative to the end cap. The stationary pad has an opening extending through the pad that is in fluid communication with an opening in the end cap. The opening in the end cap is in fluid communication with the source of pneumatic signals.
The rotary coupling also includes the shaft having a first end coupled to the rotating article handler of the equipment and a second end having an end portion rotatably received by the housing. The end portion includes a rotating pad supported in the cavity for slight axial movement relative to the shaft but in a radially fixed orientation relative to the shaft. The rotating pad thus rotates relative to the stationary pad.
The stationary pad has a first sealing face that is preferably very finely machined, ground flat, and then lapped to near perfect flatness. Likewise, the rotating pad has a second sealing face that is preferably very finely machined, ground flat, and then lapped to near perfect flatness. The shaft is received in the housing so that the first sealing face sealingly engages the second sealing face.
Sealing engagement of the first and second sealing faces is achieved in part by providing the first and second sealing faces with near perfect flatness as described above. In addition, the stationary and rotating pads are mounted so that the pads axially "float" between the end cap and the end portion of the main shaft. This float is achieved by providing the axially slidable connections between the stationary pad and the end cap and between the rotating pad and the end portion of the main shaft and by yieldably biasing the stationary pad away from the end cap and yieldably biasing the rotating pad away from the end portion of the main shaft so that the stationary and rotating pads are biased toward one another.
The stationary pad is yieldably biased away from the end cap by o-rings made from a resilient material positioned to lie between the stationary pad and the end cap. Likewise, the rotating pad is yieldably biased away from the end portion of the main shaft by o-rings made from a resilient material positioned to lie between the rotating pad and the end portion of the main shaft. These o-rings allow the stationary pad to move sightly in an axial direction relative to the end cap and the rotating pad to move slightly in the axial direction relative to the main shaft. The o-rings also allow the pads to adjust so that pads are not necessarily precisely parallel to the end cap or the end portion of the shaft, thus ensuring the sealing engagement between the sealing faces when opposing faces of the end portion and the end cap are not precisely parallel.
The rotating pad is formed to include an opening that extends through the rotating pad. The opening in the rotating pad is in fluid communication with the article handler through the conduit of the shaft.
The opening in the rotating pad and the opening in the stationary pad are radially aligned so that the openings coincide during a predetermined portion of each rotation cycle of the shaft and the rotating pad relative to the housing and the stationary pad. When the openings in the stationary and rotating pads are coincident, the openings are in fluid communication so that the article handler is in fluid communication with the pneumatic signal source. When the openings in the stationary and rotating pads are not coincident, the sealing engagement between the first and second sealing faces blocks the fluid communication between the openings in the rotating and stationary pads, blocking the fluid communication between the pneumatic signal source and the article handler. Thus, the positioning of the openings in the stationary and rotating pads operates to program the rotary coupling to communicate the pneumatic signal from the pneumatic signal source to the article handler when the article handler is at a predetermined angular orientation.
The rotating and stationary pads can additionally cooperate to define an arcuate channel in fluid communication with the openings in the rotating and stationary pads at selected portions of the rotation cycle. The channel operates to maintain the fluid communication between the openings in the rotating and stationary pads during portions of the rotation cycle at which the openings are not coincident. The channel, in effect, lengthens the portion of the rotation cycle of the shaft during which the openings in the rotating and stationary pads are in fluid communication, thereby lengthening the duration of the communication of the pneumatic signal from the pneumatic signal source to the article handler.
Lengthening the channel lengthens the portion of the rotation cycle during which the openings are in fluid communication. In addition, the channels can be formed so that the openings are not centered within the channel. Instead, the channel can be formed, for example, so that the fluid communication starts earlier in the rotation cycle and ends earlier in the rotation cycle than would occur if the opening was centered in the channel. Likewise, the channel can be formed so that the fluid communication is restored later and is blocked later in the cycle than would occur if the opening were centered in the channel. It can be seen, then, that the channel can be used to alter both the orientation of the shaft at which the openings in the rotating and stationary pads are in fluid communication and the extent of the rotation cycle during which the openings in the rotating and stationary pads are in fluid communication, thus varying the timing and duration of the communication of pneumatic signals between the pneumatic signal source and the article handler.
It is preferred that the channel is formed in the stationary pad, however channels can be formed in both the stationary and rotating pads or in only the rotating pad without altering the scope of the invention as presently perceived. It can be seen that if the channel is formed on the stationary pad, for example, the sequencing and duration of the communication of pneumatic signals between the article handler and the pneumatic signal source can be easily changed by replacing the stationary pad with a different stationary pad having a channel with a different configuration than the channel on the replaced stationary pad.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.