Abstract:
A pair of rotary pistons each have a drive shaft connectable therewith through respective one-way mechanisms. Each of the clutch mechanisms has a wrapped spring member surrounding the shaft and a linearly moveable piston to effect an operative connection between the wrapped spring and the shaft. Each linearly moveable piston controls fluid flow to one of the rotary pistons such that the linearly moveable piston will enforce actuation of the wrapped spring prior to the introduction of fluid pressure at the respective rotary piston.

Description:
TECHNICAL FIELD 
     This invention relates to piston actuators and more particularly to rotary pistons having a selective attachment to a shaft. 
     BACKGROUND OF THE INVENTION 
     Rotary control valves have a shaft member that is driven rotatably to position the valve control member in the proper position for the requested function. Rotary valves have been proposed for use in automatic shifting power transmissions to control the position of the manual control valve during operation of the transmission. For example, the valve control member has a reverse position, a neutral position and a plurality of forward drive positions. The control member has to respond to both clockwise and counterclockwise rotary input commands. 
     In one control system, the piston has a pair of one way clutch members disposed between a shaft and the piston to effect a drive connection therebetween depending on the desired direction of rotation. The one-way mechanisms are hydraulically actuated to establish a drive connection and both must be released to permit the piston to return to a central position. In another rotary valve system the piston is driven to specific stops by the hydraulic control. This requires a number of hydraulic control ports to support each stop position or a piston having multiple components. A hydraulic control system having a single control piston is described in U.S. Ser. No. 09/105,405 filed Jun. 26, 1998 and assigned to the assignee of this application. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved rotary drive system having one-way drive mechanisms. 
     In one aspect of the present invention, a pair of selectively energizable clutch members are disposed between respective pistons and a rotary shaft member. In another aspect of the present invention, the selectively energizable clutch members are one-way mechanisms. In yet another aspect of the present invention, the one-way mechanisms each include a wrapped spring clutch. 
     In still another aspect of the present invention, respective linearly moveable hydraulic pistons are selectively pressurized to actuate the one-way mechanisms. In a further aspect of the present invention, rotary pistons are disposed for fluid communication with respective ones of the linearly moveable pistons. In a yet further aspect of the present invention, the linear piston is moved to energize the respective one-way mechanism prior to the admission of hydraulic fluid to the respective rotary piston. 
     In a still further aspect of the present invention, each piston is comprised of two components with a lost motion connection therebetween which permits one component to have a longer linear travel. In a yet still further aspect of the present invention, the shorter traveling component engages a wrapped spring clutch to provide an anchor point and the longer traveling component controls fluid flow to the actuator piston. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional elevation view of a valve and control incorporating one embodiment of the present invention. 
     FIG. 2 is a view taken along line  2 — 2  in FIG.  1 . 
     FIG. 3 is a sectional elevational view of a valve and control incorporating another embodiment of the present invention. 
     FIG. 4 is a partial view of an alternative embodiment of the spring clutch connections. 
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Referring to the drawings wherein like characters represent the same or corresponding components, there is seen in FIGS. 1 and 2 a valve and control assembly  10  comprised of a control assembly  12  and a valve assembly  14 . The valve assembly  14  includes a housing  16  consisting of spaced plates  18  and  20  and an annular separator  22 . The plates  18 ,  20  and the separator  22  are joined by a plurality of fasteners  24 . An internal plate valve  26  is rotatably mounted between the plates  18  and  20 . 
     A plurality of ports  28  are formed in the plate  20 . The ports  28  supply hydraulic fluid to and direct hydraulic fluid from the valve assembly  14  in a well known manner. The valve assembly  14  is useful in controlling the operating condition of an automatically shifting power transmission, not shown. The internal plate valve  26  must be moveable to a plurality of operating positions and also be held at those positions for a period of time depending on the operating sequence. To hold the plate valve  26  at the desired positions, a detent mechanism  30  is provided. The mechanism  30  includes a pocket  32 , formed in the plate valve  26 , a spring  34 , positioned in the pocket, a plurality of sockets  36 , formed in the plate  18 , and a ball  38  urged into respective ones of the sockets  36  by the spring  34  in a well-known manner. The valve assembly  14  may be constructed similar to the structure shown in U.S. Ser. No. 09/105,405 filed Jun. 26, 1998. Other rotary valve structures can also be accommodated by the present invention. The plate valve  26  is drivingly connected with a shaft  40  which is a component of the control assembly  12 . 
     The control assembly  12  includes a cover  42 , a housing  44 , a pair of rotary pistons  46 ,  48  a pair of actuator assemblies  50  and  52  and a pair of coil springs  54 ,  56 . The coil springs  54 ,  56  are disposed helically circumjacent and radially spaced from portions of the shaft  40 . Each spring  54 ,  56  has a respective tab end  58 ,  60  that engage in pockets  62 ,  64  formed in the pistons  46  and  48  respectively. Each coil spring  54 ,  56  has a free end  66 ,  68  that are separated by a collar  70  fastened to the shaft  40 . Since each spring  54 ,  56  has a slight radial clearance with the shaft  40 , they are not self energizing. The spring  54  has a right hand helix and the spring  56  has a right hand helix. 
     The rotary piston  46  has a hub portion  72 , rotatably supported on the shaft  40  and a paddle portion  74 . The paddle portion  74  is disposed in an arcuate chamber  76  formed by the cover  42  and the housing  44 . A torsion spring  78  that has one leg  80  abutting the paddle portion  74  and another leg  82  abutting a wall  84  of the chamber  76 . The rotary piston  48  is identical with the rotary piston  46  such that the corresponding parts have been given the same numeric designation with an “A” suffix. The chamber  76 A is formed by the housing  42  and the plate  18 . The chambers  76  and  76 A are in fluid communication with respective passages  86  and  88  formed in the housing  44 . The passages  86  and  88  provide communication for the ingress of fluid between the paddle portion  74 ,  74 A and respective walls  90  and  90 A of the chambers  76  and  76 A. Passages  89  and  91  provide for the exhausting of fluid from the chambers  76  and  76 A. 
     The actuator assemblies  50  and  52  are identical and only the structure of the actuator assembly  50  will be described. The actuator assembly  50  has an actuator piston  92 , a control piston  94 , and a bias spring  96 . The control piston  94  is slidably disposed on the actuator piston  92  and in a chamber or bore  98  formed in the housing  44 . The actuator piston  92  has a head portion  100  that is disposed to be positioned in a recess  102  formed in the control piston  94  to limit the relative motion between the pistons  92  and  94 . The control piston  94  can move downward, as viewed in FIG. 1, relative to the actuator piston  92 . 
     The bias spring  96  is compressed between a wall  104  of the control piston  94  and a plug  105  secured in the housing  44 . The plug  105  has a central opening through which the actuator piston  92  extends. The plug  105  slidably supports the actuator piston  92 . The bias spring  96  urges the control piston upward in the chamber  98  and, when the head portion  100  is disposed in the recess  102 , the actuator piston  92  is urged upwardly also. The actuator piston has rotatably supported thereon a roller  106  that is aligned to contact the end  66  of the coil spring  54  to enforce frictional engagement or contact between the coil spring  54  and the shaft  40 . 
     The chamber  98  is in fluid communication with a passage  108  formed in the housing  44  and cover  42 . The passage  108  is connected with a hydraulic line  110  that is connected with a conventional electro-hydraulic control  112 . The electric-hydraulic control  112  preferably includes an electronic control unit that incorporated a preprogrammed digital computer. The control  112  establishes the pressure level in the line  110  and also distributes pressurized fluid to components of a conventional power transmission, not shown. The passage  108 A is connected with the control  112  through a hydraulic line  114 . 
     In the position shown, both of the actuator assemblies  50  and  52  are in the unactuated position. To cause clockwise rotation of the shaft  40 , and therefore the plate valve  26 , the line  110  is pressurized by the control  112 . The pressure in the line  110  and the passage  108  will cause both the actuator piston  92  and the control piston  94  to move downward in the bore  98  until the roller  106  contacts the spring  54  and enforces contact therewith. This provides a reaction anchor at the end  66  of the spring  54 . At this point, the piston  92  will be halted but, due to the lost motion mechanism provided by the spring  96 , the piston  94  will continue to move relative to the piston  92 . 
     The control piston  94  will open the chamber  98  to the passage  86  and thereby admit fluid pressure to the chamber. The pressure in chamber  76  will act on the paddle  74  to cause the piston  46  to rotate. The tab end  58  is driven by the piston  46  causing the spring  54  to contract to wrap down on and frictionally engage the shaft  40  such that the shaft  40  and the plate valve  26  are also rotated. The piston  46  will rotate to the pressure set dashed position  46 B, shown in FIG. 1 resulting in a new operating position for the plate valve  26  where the detent  30  will hold the plate valve  26 . The rotary travel of the pistons  74  and  74 A is limited to the arcuate space provided by the chambers  90 ,  90 A and the respective torsion springs  78 . 
     The pressure in the chamber  76  is then reduces such that the piston  46  can return to the spring set position. When the piston  46  is in the spring set position, the pressure in the chamber  98  will be sufficiently reduced to permit the pistons  94  and  92  to return to the spring set position under the influence of the torsion spring  78  and the fluid in the chamber  76  will exhaust through the passage  89 . The piston  46  is rotated in the opposite sense while returning to the spring set position therefore, the spring  54  will unwrap thereby permitting the piston  74  to rotate free from the shaft  40 . Thus the coil spring  54  acts as a one-way clutch. To move the plate valve  26  to the next clockwise position, the line  110 , passages  108  and  86  are repressurized by the control  112 . To rotate the shaft  40  and the plate valve  26  in the opposite or counterclockwise direction, the hydraulic line  114  is pressurized. This will result in the actuator piston  92 A being moved into abutment with the spring  56  and the control piston  94 A being sequentially actuated such that the chamber  76 A is pressurized through the passage  88  and the shaft  40  is driven counterclockwise by the piston  74 A and the spring  56 . When the pressure in the passage  108 A is released, the piston  74 A will return to the spring set position while the fluid in the chamber  76 A is exhausted through the passage  91 . 
     From the above description it should now be apparent to those skilled in the art that the shaft  40  and plate valve  26  can be controlled for rotation to a plurality of operating positions in both the clockwise and counterclockwise directions. 
     The embodiment shown in FIG. 3 is similar to the embodiment described in FIGS. 1 and 2 with the exception of a modification to the control assembly  12 A. The assembly  12 A includes a housing  120  enclosed by a cover  122 . The housing  120  cooperates with the cover  122  and the plate  18  to form respective chambers  128  and  130  in which a pair of rotary piston  132  and  134  are disposed for rotation on a shaft  136  which is connected with the plate valve  26 . Each piston  132 ,  134  is drivingly connected with a respective tab end  138  and  140  of coil springs  142  and  144 . Each spring  142 ,  144  has a respective free end  146  and  148  that are limited in axial movement by a collar  150  formed on the shaft  136 . The spring  142  has a right hand helix and the spring  144  has a right hand helix. 
     The housing  120  has two bores  152 ,  154  in each of which is slidably disposed an actuator and control piston  156 ,  156 A. An annular stop surface or locating ring  158 ,  158 A limits the upward movement of each piston  156 ,  156 A in the respective bores  152 ,  154 . The pistons  156 ,  156 A are urged toward the respective stop surfaces  158 ,  158 A by springs  160 ,  160 A. Each piston  156 ,  156 A has a head end  162 ,  162 A, slidably disposed in the respective bore  152 ,  154 , a stem portion  164 ,  164 A slidably disposed in a respective openings  166 ,  168  formed in the housing  120 . 
     Each stem portion  164 ,  164 A has a roller assembly  170 ,  170 A supported thereon. The roller assembly  170  is aligned to contact the free end  146  of spring  142  and the roller assembly  170 A is aligned to contact the free end  148  of the spring  144 . Each bore  152 ,  154  communicates through respective passages  172 ,  174  with the electro-hydraulic control  112 . The chamber  128  and the bore  152  are interconnected by a passage  176  that is closed by the head portion  162  when the actuator and control piston  156  is in the spring set position shown. The chamber  130  and the bore  154  are interconnected by a passage  178  that is closed by the head portion  162 A when the actuator and control piston  156 A is in the spring set position shown. 
     However, when the piston  156 , is moved downward by pressure in the chamber  152 , the roller assembly  170  will first anchor the spring  142 ; and then the piston  156  will open the passage  176  so that the piston  132  will be pressurized to enforce rotation of the spring  142 , the shaft  136  and the plate valve  126  in the clockwise direction in a manner described above for FIG.  1 . When the piston  156 A, is moved downward by pressure in the chamber  154 , the roller assembly  170 A will first anchor the spring  142 ; and the passage  178  will then be opened and the piston  134  will be pressurized to enforce rotation the spring  144 , the shaft  136  and the plate valve  126  in the counterclockwise direction in a manner described above for FIG.  1 . The position of the stop surfaces  158 ,  158 A, the thickness of the head portions  162 ,  162 A and the position of the passages  176 ,  178  determine the opening of the chambers  128  and  130  for pressurization. The system is designed such that the rollers  170 ,  170   a  will contact the respective free ends  146 ,  148  simultaneously with or slightly prior to the passages  176  and  178  being opened. This will insure that the springs  142  and  144  are anchored before the pistons  132  and  134  begin to move. 
     FIG. 4 describes an alternative connecting structure for the coil springs  54  and  56  in the form of springs  54 B and  56 B. The spring  54 B has a free end  66 B from which a tab  66 C extends into a slot  71  formed in a collar  70 B. The collar  77 B is free to rotate relative to the shaft  40 . The spring  56 B has a free end  68 B from which a tab  68 C extends into a slot  71 A formed in a collar  70 B. The remaining components are same as those described for FIGS. 1 and 2. With the structure shown in FIG. 4, the spring  56 B will unwrap as the spring  54 B warps and vice-versa. The piston  74 A will react against the wall  90 A and a force will be stored in the spring  56 B. This stored force will assist the torsion spring  78  in returning the piston  74  to the spring set position when the pressure in the passage  108  is relieved. Likewise when the piston  74 A is actuated, the spring  54 B will store a force which will assist in returning the piston  74 A to the spring set position. If desired, the tabs  66 C and  68 C can be connected and the collar  70 B can be eliminated. This will result in a single spring having a right hand helix portion and a right hand helix portion.