The present disclosure relates to motors and, more particularly, to a hydraulic motor.
Hydraulic motors typically receive a flow of pressurized fluid and convert the potential energy of the pressurized fluid into kinetic mechanical energy. Often, a fluid motor produces rotary motion configured to drive one or more operatively connected devices, e.g., gears or sprockets. A fluid pump is usually connected to the fluid motor to provide a substantially continuous flow of pressurized fluid to the fluid motor. The amount of mechanical energy output from a fluid motor is often varied by adjusting either the amount of flow and/or the pressure provided by the fluid pump, for example, by adjusting a stroke length of one or more pistons of the fluid pump or by restricting a pump provided constant flow and pressure via one or more valves disposed between the fluid pump and the fluid motor. These methods of adjusting the mechanical energy output of the fluid motor may undesirably waste energy by using only a portion of the delivered energy when adjusting the stroke length or by dissipating heat when restricting flow and pressure via the valves.
U.S. Pat. No. 6,651,545 (“the '545 patent”) issued to Nippert discloses a variable displacement fluid translating device. The device of the '545 patent includes a housing, a rotary cam having an eccentric cam surface, and a plurality of pistons disposed within a plurality of piston bores disposed radially with respect to the rotational axis of the rotary cam. The eccentric cam surface is in contact with the plurality of pistons and is configured to affect a reciprocal motion of the plurality of pistons relative to a respective piston bore. The plurality of piston bores are in fluid communication with a plurality of actuators and an inlet port and an outlet port. The device of the '545 patent operates as a fluid pump by driving the rotary cam forcing the plurality of pistons to reciprocate within the plurality of piston bores and force fluid therein to the inlet or outlet port. The device of the '545 patent also operates as a fluid motor by fluidly reciprocating the plurality of pistons within the plurality of piston bores to rotate the cam via the eccentric cam surface. The device of the '545 patent may selectively adjust the amount of fluid displaced when the device operates as a fluid pump by selectively adjusting one or more of the piston strokes via the plurality of fluid actuators.
The device of the '545 patent may be configured to operate as both a fluid pump and fluid motor, however, when operating as a fluid motor, the plurality of pistons may undesirably translate a relatively large reciprocating displacement thereof into a small rotary motion of the rotary cam. Additionally, the device of the '545 patent may include adjusting the amount of rotary motion by adjusting the amount of fluid displacement, however, increased range or degree of adjustability may be desirable.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.
In one aspect, the present disclosure is directed to a hydraulic motor. The hydraulic motor includes a first toothed wheel and at least one second toothed wheel configured to at least selectively engage the first toothed wheel. The hydraulic motor also includes at least one hydraulic actuator and at least one linkage operatively disposed between the at least one second toothed wheel. The at least one linkage configured to transfer a reciprocal motion of the at least one hydraulic actuator to a rotary motion of the at first toothed wheel.
In another aspect, the present disclosure is directed to a method of converting linear motion into rotary motion. The method includes selectively supplying pressurized fluid to a first actuator to selectively produce a first reciprocal motion. The method also includes transferring the selectively produced first reciprocal motion to a first toothed wheel via a first linkage. The method also includes selectively locking the first toothed wheel to the first linkage via at least a first sprag. The method further includes transferring the selectively produced first reciprocal motion to a second toothed wheel via the first toothed wheel to rotate a second toothed wheel about an axis.
First displacement assembly 14a may include a toothed wheel 20, a linkage 22, a first hydraulic actuator 24, and a first fluid path 26. Toothed wheel 20 may include a wheel rotatably supported by linkage 22 and may be configured to selectively engage an outer circumference of output wheel 12. Toothed wheel 20 may have a profiled outer circumference complementary to the profile of the outer circumference of output wheel 12. Toothed wheel 20 is further described below with reference to
First hydraulic actuator 24 may include a piston-cylinder arrangement and may be configured to selectively impart a first linear motion to linkage 22 as a function of pressurized fluid selectively supplied to a first fluid chamber 24a. First hydraulic actuator 24 may also be configured to selectively impart a second linear motion, substantially opposite in direction to the first linear motion, as a function of pressurized fluid selectively drained from first fluid chamber 24a. Pressurized fluid may be selectively supplied to and drained from first fluid chamber 24a by a hydraulic system 18. For example, hydraulic system 18 may include a source of pressurized fluid (not illustrated), a fluid reservoir (not illustrated), and a least one valve (not illustrated) configured to selectively fluidly connect the first chamber of first hydraulic actuator 24 with either the source of pressurized fluid or the fluid reservoir. First displacement assembly 14a may also include a spring 28 operatively connected to linkage 22, first hydraulic actuator 24, or other suitable element of first displacement assembly 14a, to bias first hydraulic actuator 24 in the second direction, i.e., opposite the direction in which first hydraulic actuator 24 may be biased as a function of pressurized fluid selectively supplied to first fluid chamber 24a. It is contemplated that spring 28 may have one end thereof fixed relative to axis 16. It is also contemplated that the source of pressurized fluid and/or the fluid reservoir of hydraulic system 18 may include an accumulator. It is further contemplated that hydraulic system 18 may be dedicated to first displacement assembly 14a, i.e., one of displacement assemblies 14 or, alternatively, hydraulic system 18 may be operatively connected to each of displacement assemblies 14.
Linkage 22 may include a first link 22a, a second link 22b, and a third link 22c. It is contemplated that second link 22b may be configured to pivot about a pivot point 30 fixed relative to axis 16 as a function of the first and second linear motions imparted thereto by first hydraulic actuator 24. First link 22a may include a first connection point operatively connected to toothed wheel 20 and configured to rotatably support toothed wheel 20 thereon. First link 22a may also include a second connection point operatively connected to a first end of second link 22b. Third link 22c may be operatively connected at a first connection point to first hydraulic actuator 24 and configured to reciprocate substantially therewith. Third link 22c may also include a second connection point operatively connected to a second end of second link 22b. Second link 22b may be operatively connected to pivot 30 and may be configured to rotate about pivot 30 as a function of the first and second movements of first hydraulic actuator 24 and third link 22c. It is contemplated that the first and second connection points of second link 22b may be connected to one another via any connection known in the art allowing relative movement therebetween, such as, for example, a pinned connection. It is also contemplated that second link 22b may be connected to pivot 30 at any location, such as, for example, a location disposed opposite the second connection point of link 22b with respect to the first connection point of link 22b, a location disposed opposite the first connection point of link 22b with respect to the second connection point, or a location disposed between the first and second connection points of link 22b. It if further contemplated that first, second, third links 22a-c may each include any conventional link element known in the art, such as, for example, single link plate, a plurality of link plates operatively connected together, interleaved link plates, and/or combinations thereof.
Linkage 22 may also include second hydraulic actuator 22d. Second hydraulic actuator 22d may be operatively connected between the second end of second link 22b and the first end of first link 22 and may be configured to provide a linear movement therebetween. Second hydraulic actuator 22d may include a piston-cylinder arrangement with at least a first chamber therein configured to selectively receive pressurized fluid via a first fluid path 26. First fluid path 26 may extend from the first fluid chamber 24a, through third link 22c, through second link 22b, and through first link 22a. First fluid path 26 may include one or more passageways, e.g., channels or conduits, extending through first, second, third links 22a-c that may be connected to one another at respective connection points of first, second, third links 22a-c via any suitable fluid connection, such as, for example, a partial or full circumferential groove about a pinned connection.
Sprag 36a may be oblong in shape including a first or long dimension. The extension of the plurality of actuators 44 may rotate sprag 36a about sprag axis 48 in the first direction and affect the long dimension to fixedly engage outer and inner races 32, 34 and substantially lock together outer and inner races 32, 34. Sprag 36a may also include a second or short dimension. The bias of plurality of springs 46 may rotate sprag 36a about sprag axis 48 in the second direction to affect sprag 36a to not fixedly engage outer and inner races 32, 24 and not substantially lock together outer and inner races 32, 34. It is contemplated that the bearing cage 42 may include a plurality passageways therein, e.g., channels or conduits, as part of second fluid path 40 that may be configured to fluidly communicate pressurized fluid toward third fluid path 54. It is also contemplated that the passageways of bearing cage 42 may be connected to third fluid path 54 via any suitable fluid connection, such as, for example, a partial or full circumferential groove about a pinned connection between bearing cage 42 and sprag 36a.
As illustrated in
Third fluid path 54 may configured to fluidly communicate pressurized fluid from second fluid path 40 to each of plurality of actuators 44. Third fluid path 54 may or may not be symmetrical with respect to a longitudinal axis of sprag 36a. It is contemplated that first link 22a may include two link plates disposed on opposite sides of inner race 34 and that each of the two link plates may include passageways associated with second fluid path 40. The above description of sprag 36a is equally applicable to each of plurality of sprags 36.
The disclosed motor may be applicable to any system where rotary motion may be desired. Motor 10 may convert hydraulic potential energy into mechanical kinetic energy and may be configured to provide a localized rotary motion to one or more components. The operation of motor 10 is explained below.
Referring to
Referring to
Pressurized fluid may also be communicated to second actuator 22d affecting an extension thereof. An extension of second actuator 22d may urge first link 22a in a direction away from the connection point between second and third links 22b-c. Because toothed wheel 20 may be configured to selectively engage output wheel 12 and, thus, may be located adjacent the circumference thereof, urging first link 22a away from the connection point between second and third links 22b-c may ensure toothed wheel 20 engages output wheel 12 when pressurized fluid is selectively communicated to first fluid chamber 24.
Movement of toothed wheel 20 may be transferred to output wheel 12 at a circumference thereof establishing a substantially rotary movement about axis 16. Because sprag 36a locks outer and inner races 32, 34 together, toothed wheel 20 is substantially prohibited from rotating with respect to first link 22a. Because toothed wheel 20 is prohibited from rotating and because the profiled circumference of toothed wheel is operatively connected to the profiled circumference of output wheel 12, the substantially tangential movement of toothed wheel 20 is transferred to output wheel 12 and output wheel 12 rotates about axis 16. As such, first displacement assembly 14a may cause output wheel to rotate about axis 16.
The pressurized fluid previously supplied to first fluid chamber 24a may selectively be drained therefrom. As such, spring 28 may urge linkage 22 and first actuator 24 to a non-extended position. Additionally, pressurized fluid previously supplied to sprag 36a via first, second, third fluid paths 26, 40, 54 may be similarly relieved and springs 46 may rotate sprag 36a to rotate about sprag axis 48 and affect the short dimension of sprag 36a to unlock outer and inner races from one another.
Referring to
The timing of selectively supplying and draining pressurized fluid to and from displacement assemblies 14 may affect the rotation of output 12. By draining pressurized fluid from first fluid actuator 24, as described above, second fluid actuator 22d may not urge toothed wheel 20 away from the connection point between second and third links 22b-c. As such, first link 22a and toothed wheel 20 may be allowed to pivot about the connection point between first and second links 22a-b. Such a rotation or toothed wheel 20 may be affected as output wheel 12 rotates a second degree of rotation about axis 16 affected by, for example, the adjacent one of displacement assemblies 14. That is, because the circumference of output wheel 12 and the circumference of toothed wheel 20 may be profiled, e.g., having a ratchet tooth profile, rotation of output wheel 12 by adjacent ones of displacement assemblies 14 might be resisted if toothed wheel 20 was not allowed to un-mesh from output wheel 12. It is contemplated that toothed wheel 20 may rotate about the connection point between first and second links 22a-b as a function of the profiled circumference of output wheel 12 and toothed wheel 20. For example, if output wheel 12 and toothed wheel 20 each have a ratchet tooth profile, e.g., as illustrated in
Additionally, outer race 32 of toothed wheel 20 may rotate with respect to inner race 34 and first link 22a when pressurized fluid is not selectively supplied to sprags 36. Bearings 38 may support and allow outer race 32 to rotate with respect to inner race 34 which may be fixedly connected to first link 22a. As such, the ability of outer race 32 to so rotate may further allow adjacent ones of displacement assemblies 14 to affect subsequent rotation of output wheel 12. It is contemplated that rotation of outer race 32 with respect to both inner race 34 and first link 22a may also allow a subsequent portion of the profiled circumference of toothed wheel 20 to engage output wheel 12. For example, if toothed wheel 20 includes a ratchet tooth profile, a subsequent ratchet tooth may engage output wheel 12 during a subsequent operation of first displacement assembly 14a as compared to a ratchet tooth that may have engaged output wheel during a previous operation of first displacement assembly 14.
Selectively omitting the operation of one or more of displacement assemblies 14 during actuation sequences may provide an adjustability of the rotational output of output wheel 12 and thus motor 10. For example, actuating all of displacement assemblies 14 may provide a maximum rotational output torque of motor 10, selectively omitting one or more of displacement assemblies 14 may provide decreased rotational output torque of motor 10, and actuating only one of displacement assemblies 14 may provide a minimum output torque of motor 10. It is contemplated that the rotational speed of motor 10 may inversely correspond to the rotation output torque of motor 10. For example, if motor 10 includes nine displacement assemblies 14, selectively omitting one or more displacement assemblies 14 may provide nine step change ratios, e.g., 9:9, 8:9, 7:9, 6:9, 5:9, 4:9, 3:9, 2:9, 1:9, each corresponding to the rotational degree each one of displacement assemblies 14 may rotate output wheel 12 and the combined rotational output, e.g., torque and speed, for an actuation sequence. It is also contemplated that the different step change ratios may be achieved by selectively not supplying pressurized fluid to one or more of the first fluid actuators, e.g., first fluid actuator 24, operatively associated with respective ones of displacement assemblies 14 during a particular actuation sequence. It is also contemplated that the various step changes of motor 10 may further be varied by adjusting the displacement of the first fluid actuators, e.g., first fluid actuator 24, operatively associated with respective ones of displacement assemblies 14 via hydraulic system 18, potentially providing a continuously variable output of motor 10. It is further contemplated that the various step changes of motor 10 may further be varied by providing one or more additional output wheels having different profiles than the profile of output wheel 12, e.g., output wheel 12 may have a given number of ratchet teeth and one or more additional output wheels may have more or less teeth. Output wheel 12 and the additional output wheels may be selectively engaged and disengaged with displacement assemblies by being shifted respect to displacement assemblies 14 and/or by shifting displacement assemblies 14 with respect to the additional output wheels.
Referring to
Because displacement assemblies 14 may tangentially rotate output wheel 12 about its circumference, motor 10 may convert linear movement into a substantial rotary motion. Additionally, because one or more of displacement assemblies 14 may be selectively omitted during an actuation sequence and because the amount of pressurized fluid supplied to respective displacement assemblies 14, the output of motor 10 may be substantially continuously varied.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed motor. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
This application is related to co-pending application titled “Sprag and Bearing System” filed Dec. 28, 2006 and having a patent application Ser. No. ______.