Abstract:
A reversible pneumatic motor assembly allows forward, reversing and throttling of a pneumatic motor by manipulation of a single lever with one hand. A reversing valve assembly of the motor assembly includes a tilt valve disposed in an inlet passage having a valve seat for receiving the valve to block the inlet passage. Forward and reverse passages extend from the valve assembly to the motor for driving the motor in forward and reverse directions. A shuttle connected to the lever can be moved transversely of the motor assembly. The shuttle and tilt valve are mounted for movement upon actuation of the actuator between a first position in which the tilt valve is tilted about an axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the forward passage for driving the motor in the forward direction, a second position in which the tilt valve is tilted about the axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the reverse passage for driving the motor in the reverse direction, and a third position in which the tilt valve seats on the valve seat to prevent flow of air from the inlet passage to the motor.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to pneumatically operated motors and more specifically to a pneumatic motor assembly having throttling and reversing features. 
     The present invention is an improvement on my prior air motor reversing throttle shown and described in U.S. Pat. No. 5,423,350, the disclosure of which is incorporated herein by reference. My prior invention conveniently provides for throttling and forward and reverse operation of a pneumatic motor by simple pivoting movement of a single lever ( 31 ). Throttling and direction of movement can be actuated with one hand and can also entirely stop the motor. Pivoting movement of the lever in a first direction about an axis moves a valve ( 22 ) in a valve guide bore ( 12 ) in a housing to bring one of two valve passages ( 23  or  29 ) into registration with one of the corresponding passages ( 18  and  30  or  19  and  32 ) formed in the housing to drive the air motor in a counterclockwise or clockwise direction. In a middle or stop position of the valve, neither valve passage overlies either of the corresponding passages so there is no fluid communication through the valve to the motor. In addition, the lever can be moved to vary the amount of the passage ( 23  or  29 ) which overlaps the corresponding passage ( 30  or  32 ) the motor can be throttled to run at different speeds solely by manipulation of the lever. 
     The flow of air to the valve ( 22 ) is controlled by a plunger ( 21 ) which is spring biased to seat against a valve seat to block an air inlet passage from communicating with the valve. In order to move the plunger off of its seat to permit air to flow to the valve, a stem of the plunger is received in a V-shaped notch on one side of the plunger. As the valve slides transversely the notch moves relative to the stem so that the end of the stem is pushed rectilinearly (or “perpendicularly”) to unseat the plunger and permit air to flow to the valve. The V-shape of the notch provides the same axial movement of the plunger for movement of the valve in either direction. Although my prior air motor reversing throttle works well and provides many conveniences for the operator, improvements can be made. It has been found that the interaction between the V-shaped notch and the plunger stem is such that return of the valve to the stop position is inhibited. Sometimes the force of the spring on the plunger is insufficient to move the valve and plunger to stop the motor when the lever is released. Moreover, the axial movement of the plunger can sometimes be difficult to achieve, requiring substantial force to be applied to the lever. The application of this force necessary to move the plunger off its seat can make it difficult to control the throttle with the lever. 
     SUMMARY OF THE INVENTION 
     Among the several objects and features of the present invention may be noted the provision of a pneumatic reversing motor assembly which can be actuated to start and run in forward and reverse directions by manipulation of a single lever; the provision of such motor assembly which can be throttled with the same lever; the provision of such a motor assembly which can be started and run in forward and reverse directions with minimal application of manual force to the lever; the provision of such a motor assembly which consistently returns to a stop position when manual force is released; the provision of such a motor assembly which is easy to use and economical to manufacture. 
     Generally, a reversible pneumatic motor assembly comprises a housing and a reversible motor in the housing. The housing includes an inlet connection for connecting the motor assembly to a source of pressurized air, an inlet passage extending inwardly into the housing from the inlet connection, a forward passage adapted for communicating with the inlet passage for delivering air to the motor for driving the motor in a forward direction and a reverse passage adapted for communicating with the inlet passage for delivering air to the motor for driving the motor in a reverse direction. A reversing valve assembly disposed in the housing between the inlet passage and the forward and reverse passages is capable of selectively controlling fluid communication between the inlet passage and the reversible motor by operation of an actuator mounted on the housing to selectively drive the motor in the forward and reverse directions. The reversing valve assembly comprises a tilt valve disposed in the inlet passage and receivable on a valve seat in the inlet passage to block the inlet passage. A spring biases the valve against the valve seat. A shuttle is located in the housing and connected to the actuator for transverse sliding motion in the housing. The shuttle and valve are mounted in the housing for movement upon actuation of the actuator between a first position in which the valve is tilted about an axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the forward passage for driving the motor in the forward direction, a second position in which the valve is tilted about the axis off of the valve seat and the shuttle is disposed to form a continuous air flow path from the inlet passage, through the shuttle and into the reverse passage for driving the motor in the reverse direction, and a third position in which the valve seats on the valve seat to prevent flow of air from the inlet passage to the motor. 
     Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a pneumatic tool of the present invention; 
     FIG. 2 is a fragmentary, longitudinal sectional view of the tool taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a fragmentary perspective view of the tool with a valve assembly of the tool partially exploded from a housing thereof; 
     FIG. 4A is a right side elevational view of a bushing of the valve assembly; 
     FIG. 4B is a front elevational view of the bushing; 
     FIG. 4C is a rear elevational view of the bushing; 
     FIG. 5 is an enlarged, fragmentary, longitudinal section taken from FIG.  2  and showing the valve assembly in a forward operating position; 
     FIG. 6 is the enlarge section of FIG. 5 but showing the valve assembly in a reverse operating position; 
     FIG. 7 is a section taken in the plane including line  7 — 7  of FIG. 5; and 
     FIG. 8 is a section taken in the plane including line  8 — 8  of FIG.  5 . 
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and in particular to FIGS. 1 and 2, a pneumatic tool constructed according to the principles of the present invention is indicated generally at  10 . The tool includes a housing, generally indicated at  12 , having an air inlet connection  14  at one end and an implement  16  located at an opposite end for driving an object such as a bolt (not shown) in rotation. The housing  12  is elongate and generally cylindrical for gripping in one hand. A lever  15  is pivotally mounted on the housing by connection to a mounting stud  17  fixed in the housing  12  for starting, stopping, throttling and reversing direction of the tool  10 , as will be described hereinafter. The particular tool shown is a ratchet wrench described in my prior provisional application Ser. No. 60/109,429, filed Nov. 23, 1998 and my co-pending PCT application filed Nov. 23, 1999, the disclosure of which is incorporated herein by reference. Although the pneumatic hand tool  10  is shown, the present invention has broader application to reversing pneumatic motor assemblies without regard to whether the motor assembly is driving a hand tool or, indeed, a tool of any kind. More broadly, the present invention pertains to a reversible pneumatic motor assembly without regard to the specific application of the motor assembly. However, for purposes of this description, the invention will be described in the context of a preferred embodiment of a hand tool  10 . 
     Referring to FIG. 2, the inlet connection  14  is constructed for connecting the tool  10  to a source of compressed air (not shown), which may be a conventional air compressor and compressed air storage unit. An inlet passage, generally indicated at  18 , extends inwardly from the inlet connection into the housing  12  to a transverse hole  20  in the housing which receives portions of a reversing valve assembly (generally indicated at  22 ). An axially inner portion  24  of the inlet passage  18  has a smaller diameter than an axially outer portion  26  of the inlet passage so that a shoulder is formed. A ring located at the shoulder defines a valve seat  28  engageable with a valve body  30  of a valve (generally indicated at  32 ) to normally block fluid communication between the inner and outer portions  24 ,  26  of the inlet passage  18  when the tool  10  is stopped. The valve  32  further includes a coil spring  34  engaging at one end the housing  12  on the interior of the inlet passage  18  and engaging the valve body  30  at the opposite end to bias the valve body against the valve seat  28 . A stem  36  extends from the valve body  30  through the inner portion  24  of the inlet passage and an oval center hole  38  in a bushing  40 , into an opening  42  in a shuttle  44  received in the bushing for sliding within the bushing generally transversely of the housing  12 . In the illustrated embodiment, the valve  32 , the bushing  40  and the shuttle  44  are parts of the reversing valve assembly  22 . 
     The section line for FIG. 2 (shown in FIG. 1) has a jog so that forward and reverse passages (designated  46  and  48 , respectively) may be seen which would otherwise be removed in a straight longitudinal section of the tool  10 . The forward and reverse passages  46 ,  48  extend from the transverse hole  20  in the housing  12  to an air motor  50  of the tool  10 . The inlet passage  18 , forward passage  46  and reverse passage  48  are formed into the housing  12  in the illustrated embodiment. However, these passages could be separately constituted (such as by pipes or tubes) from the housing without departing from the scope of the present invention. The air motor  50  includes a cylindrical, hollow casing  52  and a rotary vane  54  located within the casing. The rotary vane  54  has shafts (not shown) which extend through respective ends of the casing and are mounted in bearings  56  (one of which is shown in hidden lines) for rotation of the rotary vane in the casing. The forward and reverse passages  46 ,  48  extend through the casing to delivery of pressurized air to the rotary vane. Delivery of air through the forward passage  46  results in a forward (e.g., clockwise) rotation of the implement  16  of the tool  10 , and delivery of air through the reverse passage  48  results in a reverse (e.g., counterclockwise) rotation of the implement. Exhaust air from the motor  50  may exit the casing through vents (not shown) in the casing and into an exhaust passage  60  formed in the housing  12 . These vents are conventional in construction and arrangement and will not be further described herein. The exhaust passage  60  extends to an exhaust exit  62  at the same end of the tool  10  where the inlet connection  14  is located. In addition, exhaust air can be passed through whichever of the forward and reverse passages  46 ,  48  which is not being used to deliver high pressure air to the motor  50  through the valve assembly  22  to the exhaust passage  60 , as will be described hereinafter. 
     The bushing  40  of the valve assembly  22  is tubular in shape is formed with a rectangular, recessed flat  64  on an inlet side of the bushing (see FIG.  4 A). Axially spaced first and second inlet ports (designated at  66  and  68 , respectively) located in the recess flat  64  extend through the bushing  40  into its hollow interior and also open into the inner portion  24  of the inlet passage  18  so that they are permanently in fluid communication with the inlet passage. The center hole  38  in the bushing  40  which receives the stem  36  of the valve  32  is located within the recessed flat  64  between the inlet ports. Relatively large first and second windows (designated  70  and  72 , respectively) are located generally in the front side of the bushing  40  (see FIG.  4 B). The forward passage  46  in the housing  12  opens into the first window  70  and the reverse passage  48  opens into the second window  72  such that the forward passage is permanently in fluid communication with the first window and the reverse passage is permanently in fluid communication with the second window. The bushing  40  has a flat  74  on its back side (see FIG. 4C) causing the bushing  40  to be spaced from the transverse hole  20  in the housing  12  to define a transversely extending exhaust feed passage  76  communicating with the exhaust passage  60 . A first exhaust port  78  and a second exhaust port  80  in the bushing  40  place the interior of the bushing in permanent fluid communication with the exhaust feed passage  76 . The shuttle  44  within the interior of the bushing  40  controls which of the inlet ports ( 66  or  68 ) and exhaust ports ( 78  or  80 ) are operable to pass air, as will be described hereinafter. 
     The shuttle  44  is cylindrical in shape and is received in the interior of the bushing  40 . The shuttle  44  extends out of the bushing and transverse hole  20  in the housing  12  where it is pivotally connected by a pin  82  to the lever  15  at a location spaced from the pivotal connection of the lever to the housing (FIG.  2 ). The shuttle  44  extends through the exhaust passage  60 , and the exhaust passage is formed around the shuttle so that it is not blocked by the shuttle. Pivoting the lever  15  in a clockwise direction on the mounting pin  17  pulls the shuffle  44  down (as the tool  10  is oriented in FIG. 5) to a first position for forward operation of the tool  10 , and pivoting the lever in a counterclockwise direction pushes the shuttle up to a second position (FIG. 6) for reverse operation. The opening  42  which receives the stem  36  of the valve  32  is aligned with the center hole  38  of the bushing  40  and the stem passes through the center hole into the shuttle opening. The entry of the opening  42  is formed in size close to that of the diameter of the stem  36  so that the stem is substantially sealed in the opening and is moved transverse to the housing by transverse movement of the shuttle  44 . Inwardly of the opening entry, the opening  42  has a counterbore  84  of larger diameter than the entry. The counterbore  84  provides space within the shuttle  44  for the distal end portion of the stem  36  to move within the shuttle (see FIGS.  5  and  6 ). Movement of the shuttle  44  to either the first position (FIG. 5) or the second position (FIG. 6) causes the valve  32  to tilt so that a portion of the valve body  30  moves out of engagement with the valve seat  28  allowing pressurized air to pass around the valve body into the inner portion  24  of the inlet passage  18  to the bushing  40  and shuttle. Movement of the shuttle  44  toward the first position pivots the valve  32  in a counterclockwise direction about an axis transverse to the housing  12  and movement of the shuttle toward the second position pivots the valve in a clockwise direction about the axis. The shuttle  44  further includes a first circumferential channel  86  and an axially spaced second circumferential channel  88  which allow passage of air through the shuttle within the interior of the bushing  40 , as will be described. 
     Having set forth the construction of the pneumatic tool  10  of the present invention, its operation will be described. When not in use, the valve assembly  22  is in a third or neutral position, as shown in FIG. 2, in which the tool  10  is stopped. In this position, the first and second circumferential channels  86 ,  88  are out of alignment with the first and second inlet ports  66 ,  68  in the bushing  40 . Thus, the shuttle  44  blocks both the inlet ports. In addition, the stem  36  of the valve  32  is located generally parallel to the axis of the housing  12  and the valve body  30  is fully seated against the valve seat  28  blocking passage of air from the outer portion  26  to the inner portion  24  of the inlet passage  18 . The coil spring  34  biases the valve assembly  22  to this position so that whenever manual force on the lever  15  is released, the valve assembly moves automatically to the neutral position. The distal end of the stem  36  is free of engagement with the shuttle  44  so that the stem does not bind on the shuttle, but is allowed to pivot within the shuttle. 
     Pivoting the lever  15  in a clockwise direction to the first position, as shown in FIG. 5, tilts the valve body  30  off of the seat so that pressurized air passes into the inner portion  24  of the inlet passage  18 . In the first position, the first circumferential channel  86  of the shuttle  44  is in registration with the inlet port in the bushing  40 . The first channel  86  is always in registration with the first window  70  in the bushing  40  so that in the first position the air may pass into the bushing through the first inlet port  66 , around the shuttle  44  in the first channel, and out of the bushing through the first window into the forward passage  46 , as illustrated in FIG.  7 . Thus in the first position, there is a continuous path from the first inlet port  66  to the forward passage  46 . Throttling may be achieved by moving the lever  15  to vary the amount of the first channel  86  overlying the first inlet port  66 . In this way, the operator can control the speed of the motor  50  with the lever  15 . The first channel  86  is out of registration with the first exhaust port  78  so that it is blocked by the shuttle  44 . In the first position, the second channel  88  of the shuttle  44  is out of registration with the second inlet port  68  and the port is blocked by the shuttle so that pressurized air cannot pass through the shuttle to the reverse passage  48 . However, the second channel  88  is in registration with the second exhaust port  80  (shown in hidden lines in FIG. 5) and the second window  72  in the first position of the shuttle  44 . Thus, exhaust air may pass along a continuous path from the motor  50  through the reverse passage  48 , into the second window  72 , around the shuttle  44  in the second channel  88  and out the second exhaust port  80  to the exhaust feed passage  76  (FIG.  8 ). The exhaust feed passage delivers the exhaust air laterally through the housing  12  to the exhaust passage  60 . 
     Pivoting the lever  15  in a counterclockwise direction moves the shuttle  44  to the second position. The tilt valve  32  is pivoted in a clockwise direction to bring the valve body  30  off of the seat so that pressurized air again passes into the inner portion  24  of the inlet passage  18 . In the second position, shown in FIG. 6, the first circumferential channel  86  in the shuttle  44  is out of registration with the first inlet port  66  so that the first inlet port is blocked by the shuttle. However, the second circumferential channel  88  is in registration with the second inlet port  68  and the second window  72  so that pressurized air flows through the second inlet port, around the shuttle  44  in the second channel and out the second window in to the reverse passage  48  for driving the motor  50  in a reverse direction. The second channel  88  is out of registration with the second exhaust port  80  which is blocked by the shuttle  44  from passing air from the interior of the bushing  40  to the exhaust feed passage  76 . The first channel  86  is aligned with the first exhaust port  78  and the first window  70  so that exhaust air from the motor  50  may flow through the first window, around the shuttle  44  in the first channel and out of the valve assembly  22  through the first exhaust port into the exhaust feed passage  76 . In this way reverse operation of the motor  50  is achieved. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. 
     When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.