Abstract:
An actuator device self-contained within a housing and adapted to move an object. The actuator device includes a movable piston positioned in a cylinder portion of the housing. The cylinder portion defines a longitudinal axis, whereby the piston is movable along the longitudinal axis in response to an accumulation of air pressure within the cylinder portion. The actuator device also includes a rod coupled to the piston for movement with the piston. The rod at least partially extends outside of the housing to couple to the object. Further, the actuator device includes an air compressor located within the housing. The air compressor transfers air from a location in the housing outside the cylinder portion to a location inside the cylinder portion.

Description:
RELATED APPLICATIONS 
   The present application claims the benefit of Provisional Patent Application Ser. No. 60/424,531, filed on Nov. 7, 2002, which is hereby incorporated by reference. 

   FIELD OF THE INVENTION 
   This invention relates generally to actuator devices, and more particularly to actuator devices providing linear motion. 
   BACKGROUND OF THE INVENTION 
   Some conventional actuator devices may comprise a variation of a housing containing a movable piston with an attached rod therein. The rod usually extends outside of the housing and attaches to the object being actuated. A separate, remotely located power source is typically fluidly connected to the housing to provide a compressed fluid to the housing to move the piston and the rod. Conduit or hose is typically utilized to provide the fluid connection between the power source and the housing. Such a conventional actuator device may include a hydraulic or pneumatic cylinder, in combination with a hydraulic pump or an air pump, respectively. 
   Such conventional actuators may be configured, sometimes in combination with additional structure, to push or pull an object, tilt an object, open and close an object, clamp and/or grip an object, and/or raise and lower an object. 
   SUMMARY OF THE INVENTION 
   The present invention provides, in one aspect, an actuator device self-contained within a housing and adapted to move an object. The actuator device includes a movable piston positioned in a cylinder portion of the housing. The cylinder portion defines a longitudinal axis, whereby the piston is movable along the longitudinal axis in response to an accumulation of air pressure within the cylinder portion. The actuator device also includes a rod coupled to the piston for movement with the piston. The rod at least partially extends outside of the housing to couple to the object. Further, the actuator device includes an air compressor located within the housing. The air compressor transfers air from a location in the housing outside the cylinder portion to a location inside the cylinder portion. 
   The present invention provides, in another aspect, an actuating system including an actuator device self-contained within a housing and an object coupled to the actuator device. The actuator device includes a movable piston positioned in a cylinder portion of the housing. The cylinder portion defines a longitudinal axis, whereby the piston is movable along the longitudinal axis in response to an accumulation of air pressure within the cylinder portion. The actuator device also includes a rod coupled to the piston for movement with the piston. The rod at least partially extends outside of the housing to couple to the object. Further, the actuator device includes an air compressor located within the housing. The air compressor transfers air from a location in the housing outside the cylinder portion to a location inside the cylinder portion. The actuating system also includes the object coupled to a portion of the rod outside of the housing. The object is moved in response to movement of the piston. 
   The present invention provides, in yet another aspect, an actuating system including an actuator device and an object coupled to the actuator device. The actuator device includes a housing and a piston coupled to the housing by a flexible membrane. The flexible membrane divides the housing into a first chamber and a second chamber fluidly separated from the first chamber. The piston is responsive to an accumulation of air pressure within the housing. The actuator device also includes a rod coupled to the piston for movement with the piston. The rod at least partially extends outside of the housing. Further, the actuator device includes an air compressor fluidly connected with the first chamber of the housing. The air compressor is operable to generate the air pressure within the first chamber of the housing. The actuator device also includes a valve selectively fluidly connecting the first chamber and a location outside of the housing to vent the air pressure from the first chamber. The actuating system also includes the object coupled to a portion of the rod outside of the housing. The object is moved in response to movement of the piston. 
   Other features and aspects of the present invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, wherein like reference numerals indicate like parts: 
       FIG. 1  is a schematic illustration of one construction of an actuator device; 
       FIG. 2  is an exploded perspective view of the components of the actuator device of  FIG. 1 ; 
       FIG. 2   a  is an enlarged view of a housing component of  FIG. 2 ; 
       FIG. 3  is an assembled cutaway view of the actuator device of  FIG. 2 ; 
       FIG. 4  is a schematic illustration of another construction of an actuator device; 
       FIG. 5  is a partial cross-sectional view of a portion of the actuator device of  FIG. 4 ; 
       FIG. 6  is a top view of a mower deck, illustrating the actuator device of  FIG. 2  coupled to a clutch/brake assembly selectively driving a mower blades in the mower deck; 
       FIG. 7  is a top view of a mower deck, illustrating the actuator device of  FIG. 2  coupled to an idler pulley selectively tensioning a belt of a pulley system to selectively drive mower blades in the mower deck; and 
       FIG. 8  is a side view of a mower deck coupled to a riding lawnmower, illustrating the actuator device of  FIG. 1  coupled to the mower deck to raise and lower the mower deck relative to the riding lawnmower. 
   

   Before any features of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other constructions and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. 
   DETAILED DESCRIPTION 
   As shown schematically in  FIG. 1 , one construction of an actuator device  10  including an air compressor  14  and a solenoid valve  18  selectively provides pressurized air to a cylinder portion  22  of a housing  26  containing a movable piston  30  having a rod  34  attached thereto. In the illustrated construction of the actuator device  10 , the air compressor  14  provides compressed air to the cylinder portion  22 , however, the compressor  14  may be configured to provide any of a number of compressed fluids or gasses to the cylinder portion  22 . The compressor  14  is operable to provide, for example, a volumetric flow of 3 liters per minute of pressurized air at 10 psi pressure. 
   As shown schematically in  FIG. 1 , the compressor  14  and solenoid valve  18 , among other components, are enclosed within the housing  26 . The housing  26  is sealed such that a substantially fixed volume of air (or other gas) is present and maintained therein. However, in other constructions of the actuator device  10 , the housing  26  may not be sealed such that air may flow between inside and outside of the housing  26 . The housing  26  is sealed by a cover  38 . A tongue (not shown) is formed on the cover to engage a corresponding groove  42  (see  FIG. 2   a ) formed in the housing to help prevent debris or other contaminant matter from entering the housing  26  and affecting the performance of the actuator device  10 . The housing  26  is made of a petroleum-resistant and dimensionally stable plastic, such as 10% glass filled polypropylene, during a molding process. The housing  26  is formed with a draft to assist in ejecting the housing  26  from its mold after it is formed. Alternatively, other plastics having these characteristics may be used, and different types and amounts of fillers other than glass fiber may be used. Also, the housing  26  may be made of metal by such methods including, among others, die casting. 
   The piston  30  is axially movable within the cylinder portion  22  of the housing  26 . The rod  34  is coupled to the piston  30  and protrudes through an opening  46  in the housing  26 . The rod  34  may be coupled to the piston  30  in any of a number of ways, including fastening, bonding, and integrally forming. As schematically illustrated in  FIG. 1 , and as shown in  FIGS. 2 and 3 , a lip seal  50  encircles the piston  30  to substantially prevent pressurized air accumulated in the cylinder portion  22  from leaking to other portions of the housing  26 . The lip seal  50  readily adjusts itself to the changing diameter of the cylinder portion  22 , since the housing  26  is formed with a draft. In addition, when pressurized air is accumulated in the cylinder portion  22 , the pressurized air helps maintain the lip seal  50  against the cylinder portion  22  to substantially prevent the pressurized air from leaking to other portions of the housing  26 . However, in other constructions of the actuator device  10  where the cylinder portion  22  does not include a draft, an O-ring seal may be used in place of the lip seal  50 . Further, in yet other constructions of the actuator device  10 , the piston  30  may be made to provide minimal clearance between the walls of the housing  26  defining the cylinder portion  22  and the piston  30 , such that the seal  50  may not be necessary. 
   As shown schematically in  FIG. 1 , and also in  FIG. 3 , another seal  54  encircles the rod  34  to substantially prevent pressurized air accumulated in the cylinder portion  22  from leaking outside the cylinder portion  22  via the opening  46 . The seal  54  is maintained in place by a backup ring  58  fastened to the housing  26 . Like the seal  50  encircling the piston  30 , the seal  54  encircling the rod  34  may also be configured as a lip seal, among other types of seals. 
   The piston  30  and/or rod  34  are made of the same plastic as the housing  26  to ensure stable dimensional relationships between the components during varying temperature. The piston  30  and rod  34  may be molded as one piece, rather than molding separate pieces that require joining. Making the piston  30 , rod  34 , and housing  26  from the same plastic material helps ensure the components expand and contract at about the same rate and approximate amount. Alternatively, the piston  30  and/or rod  34  may be made of metal by such methods including, among others, die casting. 
   The compressor  14  includes an inlet port  62  and an outlet port  66 , whereby the air (or other gas) in the housing  26  outside the cylinder portion  22  is drawn through the inlet port  62 , compressed to an elevated pressure, and discharged through the outlet port  66 . The compressor outlet port  66  is fluidly connected to an inlet port  70  of the solenoid valve  18  via a conduit  74 . The conduit  74  may include rubber tubing, plastic tubing, or any equivalent thereof. 
   The conduit  74  also fluidly connects the outlet port  66  of the compressor  14  with a location inside the cylinder portion  22  via a cylinder port  78  and a passageway  82 . As shown in  FIG. 3 , the cylinder port  78  and the passageway  82  are integrally formed with the housing  26 . However, in other constructions of the actuator device (not shown), the passageway may be provided by a conduit separate and apart from the housing  26 . Also, in other constructions of the actuator device (not shown), portions of the conduit or the entire conduit may be integrally formed with the housing  26 . 
   In the illustrated construction of the actuator device  10 , the solenoid valve  18  is configured as a conventional two port, two position solenoid valve  18 . The solenoid valve  18  is biased toward an open position, in which the inlet port  70  is fluidly connected with an outlet port  86  of the solenoid valve  18  by an internal valve  90  within the solenoid valve  18 . Upon being energized, the solenoid valve  18  moves toward a closed position, in which the inlet port  70  is fluidly disconnected from the outlet port  86 . 
   As shown schematically in  FIG. 1 , the actuator device  10  is wired with a carrier vehicle (not shown), such as a lawnmower or a lawn tractor. The solenoid valve  18  and compressor  14  are electrically grounded to the vehicle chassis  94 , along with a negative terminal  98  of a battery  102 . Alternatively, the solenoid valve  18  and compressor  14  may be electrically grounded directly to the battery  102 . A positive terminal  106  of the battery  102  is electrically connected to the solenoid valve  18  through a normally-open switch  110 . The switch  110  can be any of a variety of user-manipulated switches including push-buttons, toggle switches, knobs, levers, and so forth. As shown schematically in  FIG. 1 , and also in  FIG. 2 , multiple conductive terminals  112  are insertable in the housing  26  to electrically connect respective positive and negative wire leads inside the housing  26  with respective positive and negative wire leads outside of the housing  26 . 
   The positive terminal  106  of the battery  102  is electrically connected to the compressor  14  through the normally-open switch  110  and a normally-closed limit switch  114 . As shown schematically in  FIG. 1 , the limit switch  114  is spliced downstream of the switch  110  such that when the switch  110  is closed, voltage is provided to the normally-closed limit switch  114 . Subsequently, if the limit switch  114  is closed, voltage is provided to the compressor  14 . The limit switch  114  is fixedly mounted to the compressor  14  via a bracket  118  (see  FIG. 2 ) such that the limit switch  114  is placed in close proximity to the piston  30 , such that selective movement of the piston  30  contacts and triggers the limit switch  114  to open the electrical circuit between the battery  102  and the compressor  14 . Alternatively, a normally-closed pressure switch (not shown) may be used rather than the limit switch  114 . The normally-closed pressure switch may be configured to open the circuit between the battery  102  and the compressor  14  when a pre-determined pressure is reached within the cylinder portion  22 . As a further alternative, any combination of electrical components and wiring that yields the same result may be used. Also, any number of safety switches (e.g., a seat switch and a transaxle switch), relays, and/or other electrical components (not shown) may be included in the electrical circuit schematically illustrated in  FIG. 1 . 
   To activate the actuator device  10  from a deactivated state, in which the piston  30  and rod  34  are fully extended from the housing  26 , the switch  110  is first closed to energize the solenoid valve  18  and the compressor  14 . Upon energizing the solenoid valve  18 , the inlet port  70  is fluidly disconnected from the outlet port  86 . The compressor  14  then pumps air through the conduit  74  and into the cylinder portion  22  via the passageway  82 . Since the solenoid valve  18  is energized, the solenoid valve  18  is maintained in a closed position, thereby providing a “plug” to the pressurized air in the conduit  74  and the cylinder portion  22 . As the cylinder portion  22  fills with air, the air pressure forces the piston  30  to axially move inside the cylinder portion  22 . As a result, the rod  34  retracts into the housing  26 . Upon reaching a pre-determined stroke, the piston  30  contacts and triggers the limit switch  114  such that the electrical circuit between the battery  102  and compressor  14  is opened, therefore de-energizing the compressor  14 . 
   The pressure is maintained within the conduit  74  and cylinder portion  22  to maintain the rod  34  in a retracted position. If air leaks from the system (i.e. from the compressor  14 , the solenoid valve  18 , the conduit  74 , or the cylinder portion  22 ), equalization of pressures within the housing  26  causes the piston  30  to move away from the limit switch  114 , therefore closing the electrical circuit between the battery  102  and compressor  14 , and re-energizing the compressor  14 . The compressor  14  pumps air through the conduit  74 , through the passageway  82 , and into the cylinder portion  22  until the amount of leaked air is replaced and the rod  34  resumes its retracted position at its pre-determined stroke, once again de-energizing the compressor  14 . 
   To de-activate the actuator device  10  from an activated state, in which the piston  30  and rod  34  are fully retracted into the housing  26 , the switch  110  is opened, therefore de-energizing the compressor  14  and solenoid valve  18 . As a result, the pressurized air in the cylinder portion  22 , passageway  82 , and the conduit  74  is vented to the interior of the housing  26  through the outlet port  86  of the solenoid valve  18 . Finally, the equalization of pressures within the housing  26  causes the piston  30  to move away from the limit switch  114 . 
   As shown schematically in  FIGS. 4 and 5 , another construction of an actuator device  122  includes the air compressor  14  and a solenoid valve  126  selectively providing pressurized air to an expansible chamber, or housing  130 , having a movable piston  134  therein with a rod  138  attached thereto. The compressor  14  is substantially the same as the compressor  14  of the actuator device  10  of  FIGS. 1–3 , and will not be further discussed. 
   In the illustrated construction of the actuator device  122 , the solenoid valve  126  is configured as a conventional three port, two position solenoid valve  126 . The solenoid valve  126  is biased toward a venting position, in which an outlet port  142  of the solenoid valve  126  is fluidly connected with a venting port  146  of the solenoid valve  126  by an internal valve  150  within the solenoid valve  126 . Upon being energized, the solenoid valve  126  moves toward a non-venting position, in which an inlet port  154  is fluidly connected with the outlet port  142  of the solenoid valve  126 . 
   The outlet port  66  of the compressor  14  is fluidly connected to the inlet port  154  of the solenoid valve  126  by a conduit  158 . The conduit  158  may include rubber tubing, plastic tubing, or any equivalent thereof. The outlet port  142  of the solenoid valve  126  is also fluidly connected to an inlet port  162  of the housing  130  by additional conduit  158 . As shown in  FIG. 5 , the housing  130  includes a flexible membrane  166  having the piston  134  and rod  138  attached thereto. The flexible membrane  166  also fluidly separates the housing  130  into two portions, a pressurized portion  170  and a venting portion  174 . The housing  130  further includes a venting port  178  to allow air to either escape or enter the venting portion  174 , depending on the direction of movement of the piston  134 . 
   As shown schematically in  FIG. 4 , the solenoid valve  126  and compressor  14  are electrically grounded to the chassis  94  of the carrier vehicle (not shown), such as a lawnmower or a lawn tractor, along with the negative terminal  98  of the battery  102 . Alternatively, the solenoid valve  126  and compressor  14  may be electrically grounded directly to the battery  102 . The positive terminal  106  of the battery  102  is electrically connected to the solenoid valve  126  through the normally-open switch  110 . As previously stated, the switch  110  can be any of a variety of user-manipulated switches including pushbuttons, toggle switches, knobs, levers, and so forth. 
   The positive terminal  106  of the battery  102  is electrically connected to the compressor  14  through the normally-open switch  110  and the normally-closed limit switch  114 . As shown schematically in  FIG. 4 , the limit switch  114  is spliced downstream of the switch  110  such that when the switch  110  is closed, voltage is provided to the normally-closed limit switch  114 . Subsequently, if the limit switch  114  is closed, voltage is provided to the compressor  14 . The limit switch  114  is fixedly mounted to the housing  130  such that the limit switch  114  is in close proximity to the rod  138  and that selective movement of the rod  138  triggers the limit switch  114  and opens the circuit between the battery  102  and the compressor  14 . Alternatively, a normally-closed pressure switch (not shown) may be used rather than the limit switch  114 . The normally-closed pressure switch may be configured to open the circuit between the battery  102  and the compressor  14  when a pre-determined pressure is reached within the pressurized portion  170  (see  FIG. 5 ). As a further alternative, any combination of electrical components and wiring that yields the same result may be used. Also, any number of safety switches (e.g., a seat switch and a transaxle switch), relays, and/or other electrical components (not shown) may be included in the electrical circuit schematically illustrated in  FIG. 1 . 
   To activate the actuator device  122  from a deactivated state, in which the piston  134  and rod  138  are fully extended from the housing  130 , the switch  110  is first closed to energize the solenoid valve  126  and the compressor  14 . Upon energizing the solenoid valve  126 , the inlet port  154  is fluidly connected with the outlet port  142 . The compressor  14  then pumps air through the solenoid valve  126  and into the pressurized portion  170  of the housing  130 . As the pressurized portion  170  of the housing  130  fills with air, the piston  134  moves in accordance with the flexible membrane  166 . Further, the rod  138  is forced to retract within the housing  130 . Upon fully retracting, the rod  138  contacts and triggers the limit switch  114  such that the electrical circuit between the battery  102  and compressor  14  is opened, therefore de-energizing the compressor  14 . 
   The pressure is maintained within the conduit  74  and the pressurized portion  170  of the housing  130  to maintain the rod  138  in the fully retracted position. If air leaks from the system (i.e. from the compressor  14 , the solenoid valve  126 , the conduit  158 , or the housing  130 ), equalization of pressures within the housing  130  causes the rod  138  to move away from the limit switch  114 , therefore closing the electrical circuit between the battery  102  and compressor  14  and re-energizing the compressor  14 . The compressor  14  pumps air through the solenoid valve  126  and into the pressurized portion  170  of the housing  130  until the amount of leaked air is replaced and the rod  138  resumes its fully retracted position, once again de-energizing the compressor  14 . 
   To de-activate the actuator device  122 , the switch  110  is opened, therefore de-energizing the compressor  14  and solenoid valve  126 . Upon de-energizing the solenoid valve  126 , the outlet port  142  is fluidly connected with the venting port  146 . As a result, the pressurized air in the pressurized portion  170  of the housing  130  and conduit  158  is vented to the atmosphere through the venting port  146  of the solenoid valve  126 . Finally, the equalization of pressures within the housing  130  causes the piston  134  to move in accordance with the flexible membrane  166 , and the rod  138  to move away from the limit switch  114 . 
   Although not shown in  FIG. 4 , the compressor  14 , the solenoid valve  126 , and the conduit  158  may be packaged inside the housing  130 , rather than being positioned remotely from the housing  130 . 
     FIG. 6  illustrates an actuating system  182  including the actuator device  10  providing movement to an object in the form of a lever  186  of a clutch/brake assembly  190  typically found in lawn and garden equipment, such as lawnmowers and lawn tractors, and as shown and described in U.S. Pat. No. 5,570,765. As shown in  FIG. 6 , the clutch/brake assembly  190  is utilized to engage and disengage multiple mower blades (not shown) driven by a system of belted pulleys. Although only one specific configuration of the actuator device  10  in combination with the clutch/brake assembly  190  is shown, it should be known that the configuration of the actuator device  10  with the clutch/brake assembly  190  is not limited to what is shown in  FIG. 6 . Also, although the actuator device  10  of  FIGS. 1–3  is shown providing movement to various objects in  FIGS. 6–7 , it should be known that the actuator device  122  of  FIG. 4  may also be used. 
   The rod  34  of the actuator device  10  is coupled to the lever  186  via a resilient member. In the illustrated construction of the actuating system  182 , the resilient member is in the form of a spring  194 . The spring  194  is coupled between the rod  34  and the lever  186  to provide a window of adjustment of the force applied to the lever  186 . Any of a number of conventional methods of coupling the rod to the spring and the spring to the lever may be used. Upon activation of the device  10 , the rod  34  is retracted into the housing  26 , causing the spring  194  to stretch and the lever  186  to pivot. The spring  194  can be sized (both length and stiffness), according to the amount of retraction of the rod  34 , to provide a desired force on the lever  186 . In the illustrated actuating system  182 , once a linear force of about 50 pounds is achieved in the spring  194 , the lever  186  is caused to pivot and engage the clutch/brake assembly  190 . After the lever  186  pivots, the spring  194  will continue to stretch until the rod  34  is retracted the amount governed by the stroke of the piston  30 . The device  10  may be configured to provide a somewhat slow, and steady engagement of the clutch/brake assembly  190  to prevent jarring impact forces as a result of rapidly engaging the clutch/brake assembly  190 . Also, the device  10  may be configured to disengage the clutch/brake assembly  190  very quickly. 
   As shown in  FIG. 7 , another actuating system  198  may include the device  10  actuating an idler pulley  202  to engage a belt  206  of a pulley system on a mower deck  210  carried by a riding lawnmower (not shown). When activated, the device  10  is operable to engage the idler pulley  202  such that the idler pulley  202  tensions the belt  206  so that torque may be transferred from a driving pulley  214  to driven pulleys  218  in the system, thereby engaging mower blades in the mower deck  210 . When deactivated, the device  10  is operable to disengage the idler pulley  202  from the belt  206 , such that the idler pulley  202  loosens the belt  206  so the belt  206  slips on the pulleys  214 ,  218  and does not transfer torque from the driving pulley  214  to the driven pulleys  218 , thereby disengaging the mower blades in the mower deck  210 . Like the system  182  of  FIG. 6 , the spring  194  may be utilized in the system  198  of  FIG. 7  to adjust the force applied to the idler pulley  202  by the device  10 . Further, the device  10  may be configured in the system  198  of  FIG. 7  to provide a slow engagement of the idler pulley and a rapid disengagement, like the device in the system  182  of  FIG. 6 . 
   As shown in  FIG. 8 , yet another actuating system  222  may include the device  10  raising and lowering a mower deck  226  carried by a riding lawnmower. When activated, the device  10  is operable to raise the mower deck  226  such that mower blades (not shown) in the mower deck  226  are displaced upwardly relative to the riding lawnmower. When deactivated, the device  10  is operable to lower the mower deck  226  such that the mower blades are displaced downwardly relative to the riding lawnmower. Like the systems  182 ,  198  of  FIGS. 6 and 7 , the spring  194  may be utilized in the system  222  of  FIG. 8  to adjust the force applied to the mower deck  226  by the device  10 . Further, the device  10  may be configured in the system  222  of  FIG. 8  to raise or lower the mower deck  226  slowly, or raise or lower the mower deck  226  quickly.