Abstract:
Compressors are provided which include a motor having a drive shaft; a compression chamber, having an inlet and an outlet; a diaphragm, disposed within the compression chamber such that when the diaphragm is deflected back and forth between a first position and a second position air is drawn in through the inlet and forced out through the outlet; a crankshaft, operatively connected to the drive shaft; a shuttle, configured to be displaced transversely by rotational movement of the crankshaft, and positioned to deflect the diaphragm by its transverse movement; and a guide configured to inhibit non-transverse motion of the shuttle. In some implementations, the compressor occupies a total volume of less than about 15 cubic inches.

Description:
TECHNICAL FIELD 
   This invention relates to compressors. 
   BACKGROUND 
   Small compressors have been used to deliver a stream of air to a user of a hand-held oral care devices, e.g., as described in WO 2004/049968. It is desirable that such compressors be compact, to provide a personal care device having an ergonomic shape, while also being efficient. 
   SUMMARY 
   Aspects of the invention feature small, compact compressors. The small size and compact geometry of the compressors allows the compressors to be contained in ergonomically shaped housings such as the housing of a hand-held oral care device or other personal care device. 
   In one aspect, the invention features a compressor including: (a) a motor having a drive shaft; (b) a compression chamber, having an inlet and an outlet; (c) a diaphragm, disposed within the compression chamber such that when the diaphragm is deflected back and forth between a first position and a second position air is drawn in through the inlet and forced out through the outlet; (d) a crankshaft, operatively connected to the drive shaft; (e) a shuttle, configured to be displaced transversely by rotational movement of the crankshaft, and positioned to deflect the diaphragm by its transverse movement; and (f) a guide configured to inhibit non-transverse motion of the shuttle. 
   The compressor preferably occupies a total volume (i.e., the volume of the compressor including all of the components listed above) of less than about 15 cubic inches, e.g., less than 10 inches. In some cases, the total volume occupied by the compressor may be even smaller, e.g., 5 cubic inches or less. 
   Preferred compressors have a linear configuration. By “linear configuration,” we mean that the motor that drives the compressor and the housing in which the components of the compressor are contained (the compressor housing) are linearly aligned, and of a similar diameter. 
   In some preferred compressors, the guide is configured to restrict movement of the shuttle to movement along an axis perpendicular to the plane of the planar surface of the diaphragm. In some implementations, the compressor comprise two diaphragms, each diaphragm being disposed within a compression chamber, and the shuttle and crankshaft are configured so that back and forth movement of the shuttle deflects the diaphragms in alternation, resulting in alternating compression in the two chambers. 
   In some embodiments, the compressors exhibit one or more of the following advantages. The compressor provides good air pressure and flow. In some implementations, the compressor has an output of at least 4 liters/min at a pressure of 15 psi, or at least 3 liters/min at a pressure of 8 psi. The compressor has a “sandwich” configuration for ease of assembly. The compressor exhibits minimal diaphragm wobble, resulting in high output and long diaphragm life. Like conventional diaphragm compressors, the output air is clean, i.e., substantially free of contaminants such as lubricant and particulate material. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  is a perspective view of a compressor according to one embodiment of the invention. 
       FIG. 1A  is a cross-sectional view of the compressor, taken along line A-A in  FIG. 1 . 
       FIG. 2  is a partially exploded perspective view showing the components of the compressor of  FIG. 1  (only one side of the dual diaphragm compressor assembly is exploded out; the other half remains in the compressor housing). 
       FIG. 3  is an enlarged exploded view of a subset of the components of the compressor. 
       FIG. 4  is a highly enlarged perspective view of a counterweight assembly used in the compressor of  FIGS. 1-2 . 
   

   DETAILED DESCRIPTION 
   The compressors described herein may be used, for example, in hand-held oral care devices, for example those described in U.S. Ser. No. 10/960,467, “Oral Care Systems, Oral Care Devices and Methods of Use,” filed Oct. 7, 2004, the complete disclosure of which is incorporated herein by reference. The compressor may be contained within the handle of the hand-held device, or in some cases may be disposed in a docking station with which the handle is in fluid communication. 
   As discussed above, it is preferred that the compressor have a linear configuration. In the embodiment shown in  FIGS. 1-3 , a linear configuration is accomplished by using a shuttle to replace connecting rods used in conventional diaphragm and piston compressors. In conventional compressors, typically the motor and compressor housing are perpendicularly aligned, and thus the compressor geometry is less suitable for ergonomically fitting into a handle. 
   Referring to  FIGS. 1-3 , compressor  600  includes a compressor assembly  602  and a motor  604 , joined to the compressor assembly by a motor mount  601  that includes a counterweight  605  ( FIG. 4 ) that is mounted on the crankshaft of the compressor assembly, and a keyed shaft coupling  607  that is mounted on the motor shaft, e.g., by a set screw. The counterweight  605  is generally fan-shaped (has the shape of a half of a disk), minimizing the space occupied by the counterweight and reducing compressor vibration. Preferably, as shown, the compressor assembly is joined directly to the motor, without the use of a bevel gear. The counterweight  605  includes a slot  660  that is coupled with cooperating protrusions  662  on the keyed coupling  607  to join the motor shaft to the crankshaft. This slot/key coupling eliminates the need for precise alignment of the motor shaft and crankshaft assembly. It also allows relatively large amounts of torque to be transferred from the motor to the compressor assembly with minimal power loss and coupling size. 
   Compressor assembly  602  includes two halves, each half including a diaphragm and valve head assembly  603 , shown in detail in  FIG. 2  and discussed below. Each diaphragm and valve head assembly  603  includes its own air intake and outlet, and each provides a flow of compressed air, as will be explained below. Compressor  600  may have, for example, a diameter of less than about 1.25 inch, with an output pressure of at least 15 psi and flow rate of at least 4 liters/min. 
   Referring to  FIGS. 2-3 , a crankshaft  606 , which extends from and is driven by motor  604 , causes the alternating deflection of two diaphragms  608 A,  608 B, disposed on opposite sides of the shuttle  610 , each diaphragm being part of one of the diaphragm and valve head assemblies. Crankshaft  606  includes a rod  621 , eccentrically mounted on a pair of shaft mounts  611 A,  611 B, and a pair of rollers or bearings  614 A,  614 B. The lower shaft mount  611 A is collinearly mounted on a drive shaft of the motor  604 , so that rotation of the drive shaft causes crankshaft  606  to drive the shuttle  610  back and forth, resulting in deflection of the diaphragms. 
   Shuttle  610  includes a rectangular slot  612 , through which the crankshaft extends, with rollers  614 A,  614 B of the crankshaft ( FIG. 2 ) being dimensioned to contact the inner wall  616  of the slot  612 . When the crankshaft rotates, the shuttle  610  translates back and forth along a center axis A of the diaphragms (arrows,  FIG. 3 ). This motion of the shuttle pushes the diaphragms  608 A,  608 B in and out of respective compression chambers  618 A,  618 B, defined by a pair of elastomeric domes  619  ( FIG. 1A ) that are positioned in housing  620 . Deflection of the diaphragms by the shuttle draws air into the compression chambers and then expels air out of the outflow of the compressor. Each of the diaphragms includes a convolute  622 , which causes the diaphragms to deflect with a rolling movement, which tends to extend the life of the diaphragms. The use of the shuttle  610  minimizes the distance between the two diaphragms to the thickness of the shuttle, e.g., to less than about 0.5 inch. 
   For maximum efficiency and diaphragm life, it is desirable that motion of the shuttle be limited, as much as possible, to motion along axis A. The rectangular shape of slot  612  inhibits motion in other directions. Motion in other directions is further inhibited by a guide pin  630  that extends from each of a pair of guide disks  628 , generally along axis A. Referring to  FIG. 1A , each guide pin is mounted for sliding movement in a guide sleeve  632  in housing  620 . Thus, non-axial movement of the shuttle and diaphragm is constrained by guide disk  628  which moves linearly along axis A due to the sliding engagement of guide pin  630  in guide sleeve  632 . It is generally preferred that the guide pins be formed of durable, smooth materials, for example polished stainless steel, e.g., having a hardness of about Rc 16 to 68, preferably about 48 to 54, and that the guide sleeves be formed of low friction materials, for example polymers such as TEFLON, DELRIN, and PEEK polymers. 
   Because the guide pins inhibit wobbling and other non-axial movement, the headspace clearance, i.e., the distance between the diaphragm and dome at the top of the compression stroke, is reduced. Generally, the headspace clearance is less than about 0.050″, preferably less than about 0.025″, and most preferably less than about 0.010″. Because the diaphragm can get closer to the dome, the headspace that would have otherwise been needed to compensate for diaphragm wobble can instead be used for additional stroke volume, thereby increasing compression. 
   The use of the guide pins and guide sleeves generally requires venting of the air that is moving inside the sleeve, under the force of the guide pin. This may be accomplished in any desired manner. For example, the top of the guide sleeve may be open to the atmosphere, in which case an o-ring would generally be placed around the guide pin as a seal. Alternatively, the pin/sleeve gap may be increased, e.g., by making the guide pin diameter sufficiently small so that air in the sleeve can escape into the compression chamber through the gap. Other alternatives include using a hollow guide pin that is vented through its side wall, and routing air through grooves on the pin surface and/or channels in the cap and housing. 
   It is advantageous, for ease of manufacturing, that the compressor has a “sandwich” or “stacked” configuration. Referring to  FIG. 2 , each side of the compressor is assembled as a stack including the disk, diaphragm and shuttle, and, sandwiching the assembly together, an outer cap  650 , a middle cap  652  and the housing  620 . Outer cap  650  and middle cap  652  includes through-channels for passage of air from inlet  634  and to outlet  638 . This sandwich configuration may allow the compressor to be mass-produced using conventional molding processes. 
   Referring to  FIG. 1A , when the compressor is in use, air is drawn into each side of the compressor through inlet  634 . Air is then compressed first in one chamber  618 A, and then in the other chamber  618 B, by the reciprocating motion of the shuttle. Thus, air is expelled first from one air outlet  638  and then from the other, providing a steady stream of compressed air. Inlet  634  and outlet  638  are provided with valves  636  and  640 , respectively, (e.g., flapper valves) to control the flow of air into and out of the compressor. The back and forth movement of the shuttle, resulting in this alternating compression in the two chambers, minimizes pumping losses by eliminating the need to vent “crankcase-side” air from the compressor. Because there is no need to vent air from the compressor, there is also no need to release such vented air from the device in which the compressor is contained, which may be advantageous, for example, if the compressor is enclosed within the handle of a hand-held device. Moreover, because there is no need to vent air, a possible leak point is eliminated, which may be advantageous for devices that dispense a liquid and/or are used in a wet environment. 
   If desired, a similar linear configuration could be used in a single diaphragm compressor, or in compressors having more than two diaphragms, e.g., three or more. The compressor can be converted to a single diaphragm compressor simply by removing one diaphragm from one of the sides. This configuration reduces power requirements, but will also produce a corresponding decrease in output. Redesigning the single diaphragm configuration to eliminate unused portions of the housing can reduce the size of the compressor. 
   A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. 
   For example, while the compressors described herein are particularly suited for use in oral care devices, as discussed above, they may be used in any application in which a high efficiency, compact compressor is needed. Other applications include various hand-held devices and containers that expel air or other products (in the latter case, the compressed air generated by the compressor may be used in place of a propellant or pump to provide a dispensing pressure.) 
   Moreover, the guide pins may be fixed in the domes, rather than extending from the shuttle. In this case, the shuttles would include sleeves that would allow the shuttles to slide along the pins, with a seal provided around each sleeve. Also with regard to the guide pins, more than one pin may be provided to guide each shuttle, if desired. 
   While the use of the compressor to supply compressed air has been discussed above, the inlet and outlet may be reversed, and the compressor used to apply suction. 
   While a cylindrical compressor is shown in the drawings, the compressor may have any desired elongated shape. For example, it may be oval or rectangular in cross-section. 
   Additionally, the counterweight may be positioned at other locations perpendicular to the A axis, for example on the side of the compressor opposite the motor. 
   Accordingly, other embodiments are within the scope of the following claims.