Abstract:
This invention is a bidirectional hydraulic actuator comprising a piston assembly positioned within a housing. The piston assembly is configured to move linearly within the housing. A gland is operatively connected to the piston assembly. The gland is configured as a rigid longitudinally annular member with a first end, a second end, a sidewall and is open on the first end and substantially closed on the second end which forms an inside and an outside of the annular member. The gland is further configured with a lip extending from around the outside of the first end of the gland. A pressurizing fluid exerts pressure on the inside of the gland to move the piston assembly a first direction, then, a fluid exerts pressure on the outside of the gland and the lip of the gland to move the piston assembly opposite the first direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to hydraulic actuators. Specifically, this invention relates to a bi-directional hydraulic actuator.  
         [0002]     Hydraulic actuators are commonly used on equipment today. Hydraulic actuators work because a force or pressure in a closed fluid system that is applied to one point is transferred to another point in the same closed system. This is typically accomplished by using an incompressible or nearly incompressible fluid. The force that is applied at one point in the system can be multiplied at another point in the system to create a very powerful force which can be used for moving mechanical devices.  
         [0003]     One such bi-directional hydraulic actuator is shown in U.S. Pat. No. 6,626,055. In this patent the two pressure chambers receive a pressurizing fluid in either of the pressure chambers which causes the rack to move in the direction away from the pressure of the pressurizing fluid. As the rack moves, the teeth engage the teeth of a pinion gear. Thus, the linear movement of the rack creates a rotational movement of a pinion which rotates around a point in the center of the pinion.  
         [0004]     One problem with this type of hydraulic actuator is that in order to have bi-directional motion of the rack, the pistons must be located at opposite ends of one another and thus creating a relatively long actuator assembly. Therefore, it is desirable to have a hydraulic actuator which creates bi-directional motion by having a shorter rack assembly for the same relative amount of rotational movement.  
         [0005]     The primary objective of the present invention is to provide an improved hydraulic actuator.  
         [0006]     Another objective of the present invention is to provide an actuator which is enclosed within a housing and thus increases the life of the actuator.  
         [0007]     A further objective of the present invention is to create an actuator which uses rack and pinion gearing to create rotational movement on one or more mechanical arms.  
         [0008]     A still further objective of the present invention is to create a hydraulic actuator in which greater force can be created in one direction than is created using the actuator in the opposite direction.  
         [0009]     Yet another objective of the present invention is the provision of a hydraulic actuator which is economical to manufacture, durable in use, and efficient in operation.  
         [0010]     A still yet another objective of the present invention is to provide an improved method of creating bidirectional linear motion in a hydraulic actuator using a shorter piston assembly within an enclosed housing.  
         [0011]     One or more of these or other objects of the invention will be apparent from the specification and claims that follow.  
       SUMMARY OF THE INVENTION  
       [0012]     The foregoing objects may be achieved by a hydraulic actuator comprising a rack assembly positioned within a housing. The rack assembly is configured to move linearly within the housing. The rack assembly comprises at least one set of gear teeth. The rack assembly further comprises a rack gland operatively connected to a rack assembly. The rack gland is configured as a rigid longitudinal annular member with a first end, a second end, and a sidewall. The annular member is open on the first end and substantially closed on the second end forming an inside and an outside of the annular member. The annular member is further configured with a lip extending from the annular member around the outside of the first end. At least one pinion gear is rotatably situated within the housing so that the pinion gear contacts a set of gear teeth and rotates as the rack assembly moves linearly within the housing.  
         [0013]     A further feature of the present invention involves a hydraulic actuator configured so that a rack assembly moves within a housing by force of oil exerting pressure on a rack gland.  
         [0014]     A further feature of the present invention involves a hydraulic actuator wherein a portion of a pinion gear extends outside of the housing.  
         [0015]     A further feature of the present invention involves a hydraulic actuator comprising at least one arm operatively connected to a pinion gear.  
         [0016]     A further feature of the present invention involves a hydraulic actuator wherein a rack assembly and a rack gland are encased within a housing.  
         [0017]     A further feature of the present invention is a hydraulic actuator wherein a rack gland is configured so that a surface area inside an end of an annular member is less than the surface area outside of the same end of the same annular member.  
         [0018]     A further feature of the present invention involves a hydraulic actuator configured so that a fluid exerts pressures on an inside of a second end of an annular member to move a rack assembly a first direction. The actuator is further configured so that the fluid exerts pressure on the outside end of a second end of an annular member and a lip to move the rack assembly opposite the first direction.  
         [0019]     A further feature of the present invention involves a hydraulic actuator with a second end of an annular member and a lip which are located apart from one another on the annular member.  
         [0020]     The foregoing objects may also be achieved by a bi-directional hydraulic actuator comprising a piston assembly positioned within a housing. The piston assembly is configured to move linearly within the housing. The piston assembly comprises a gland operatively connected to the piston assembly. The gland is configured as a rigid longitudinal annular member with a first end, a second end, and a sidewall. The annular member is open on the first end and substantially closed on the second end forming an inside and an outside of the annular member. The annular member is further configured with a lip extending from the annular member around the outside of the first end.  
         [0021]     A further feature of the present invention involves a bi-directional hydraulic actuator configured so that a fluid exerts pressure on the inside of a second end of an annular member to move a piston assembly a first direction. The actuator is further configured so that a fluid exerts pressure on the outside end of the second end of the annular member and a lip on the first end to move the piston assembly opposite the first direction.  
         [0022]     A further feature of the present invention involves a bi-directional hydraulic actuator wherein at least one shaft or linkage is operatively connected to a piston assembly.  
         [0023]     A further feature of the present invention involves a bidirectional hydraulic actuator wherein a shaft extends outside of a housing.  
         [0024]     The foregoing objects may also be achieved by a hydraulic clamping vehicle comprising a vehicle. The vehicle is configured with an apparatus for clamping items. The apparatus for clamping items comprises a rack assembly positioned within a housing. The rack assembly configured to move linearly within the housing. The rack assembly comprises at least two sets of gear teeth. The rack assembly further comprises a rack gland operatively connected to the rack assembly. The rack gland configured as a rigid longitudinal annular member with a first end, a second, and a sidewall. The annular member is open on the first end and substantially closed on the second end forming an inside and an outside of the annular member. The annular member further configured with a lip extending from the annular member around the outside of the first end. At least two pinion gears are rotatably situated within the housing so that the pinion gears contact the set of gear teeth and rotate as the rack assembly moves linearly within the housing. At least one arm is operatively connected to each of the pinion gears which move in a clamping motion.  
         [0025]     The foregoing objects may also be achieved by a method of creating bi-directional hydraulic motion within a housing comprising the steps of: providing a housing, a piston assembly, a gland and a fluid; configuring the housing so that the piston assembly moves linearly within the housing; configuring the gland as a rigid longitudinal annular member with a first end, a second end, and a sidewall; further configuring the annular member as open on the first end and substantially closed on the second end, forming an inside and an outside of the annular member; further configuring the annular member with a lip extending from the annular member around the outside of the first end operatively connecting the gland to the piston; exerting fluid under pressure on the inside of the second end of the annular member to move the piston assembly a first direction; and, exerting fluid under pressure on the outside end of the second end of the annular member and the lip to move the piston assembly opposite the first direction.  
         [0026]     A term that needs to be defined for this invention is a gland. A gland for the purpose of this invention is a sliding machine part designed to slide when a greater fluid force is exerted on one side of the gland than is exerted on the other side of the gland.  
         [0027]     This invention discusses a rack assembly operatively connected to a gland. In addition, this invention discusses a piston operatively connected to a gland. The two devices work the same. The difference is that a rack assembly has gear teeth on one or more sides of the assembly whereas the piston does not. Both the rack assembly and the piston can be configured as one piece with the gland or assembled together from multiple parts.  
         [0028]     The term equipment for the purposes of this invention means any equipment, stationary or mobile, which utilizes fluid power. Fluid power encompasses hydraulics as well as pneumatics. The preferred embodiment of this invention utilizes hydraulics, however pneumatics are also considered by this invention even though the pneumatic fluid is easily compressible. Additionally, the terms fluid, oil or hydraulic refer to any fluid, liquid or gas.  
         [0029]     Additionally, the term vehicle as contemplated for this invention can be on road, off road, land, sea, air, or space vehicles. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]      FIG. 1  shows a three dimensional view of one embodiment of the hydraulic actuator.  
         [0031]      FIG. 2  shows a top view of one embodiment of the hydraulic actuator.  
         [0032]      FIG. 3  shows a cut-away view showing the interior of one embodiment of the hydraulic actuator with the arms at zero rotation.  
         [0033]      FIG. 4  shows a cut-away view of one embodiment of the hydraulic actuator with the arms at full rotation.  
         [0034]      FIG. 5  shows a cut-away view of one embodiment of the hydraulic actuator with the arms at half rotation.  
         [0035]      FIG. 5A  shows an enlarged view of the oil channel.  
         [0036]      FIG. 6  shows an expanded view of one embodiment of the hydraulic actuator.  
         [0037]      FIG. 7A  shows one embodiment of a four-arm grabber assembly open using the hydraulic actuator.  
         [0038]      FIG. 7B  shows one embodiment of a four-arm grabber assembly closed using the hydraulic actuator.  
         [0039]      FIG. 7C  shows one embodiment of a vehicle using a four-arm grabber assembly with the hydraulic actuator.  
         [0040]      FIG. 7D  shows another embodiment of a four-arm grabber assembly closed using the hydraulic actuator.  
         [0041]      FIG. 7E  shows another embodiment of a vehicle using a four-arm grabber assembly with the hydraulic actuator.  
         [0042]      FIG. 8A  shows one embodiment of a two-arm grabber assembly using the hydraulic actuator.  
         [0043]      FIG. 8B  shows a side view of one embodiment of a vehicle with a two-arm grabber assembly using the hydraulic actuator.  
         [0044]      FIG. 8C  shows a top view of one embodiment of a vehicle with a two-arm grabber assembly using the hydraulic actuator.  
         [0045]      FIG. 9A  shows one embodiment of a clamshell grabber assembly opened using the hydraulic actuator.  
         [0046]      FIG. 9B  shows one embodiment of a vehicle with a clamshell grabber assembly using the hydraulic actuator.  
         [0047]      FIG. 9C  shows another embodiment of a clamshell grabber assembly closed using the hydraulic actuator. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0048]     The hydraulic actuator of the current invention is best used for grabbing or grappling objects. However, it can be used for numerous other purposes. The preferred embodiment of the current invention works like a rack and pinion rotary actuator where there is a pinion on each side of a double-sided rack. This makes the pinions rotate in opposite directions.  
         [0049]     A unique feature of this invention is how the rack is translated with fluid in a very compact space. Inside the rack, is essentially a double displacement linear actuator that nests inside itself to reduce the working space required. As fluid is displaced into the chamber on one side or the other of the nesting diameters internal to the rack, the rack displaces in that direction when used as a grabber assembly, this causes the gears to rotate and either grip or open up a grabber.  
         [0050]     The current invention is shown in  FIGS. 1-6  and  8 - 9  as a two-sided device. However it is also contemplated that the current invention could be three-sided, four-sided or any number of sides which are necessitated. For example, a three or four-sided arm grapple could be used on devices such as those on cranes or logging equipment (see  FIG. 7 ) to pick up debris, logs, or etc.  
         [0051]      FIGS. 1 and 2  show one embodiment of the hydraulic actuator assembly  10 .  FIG. 1  shows a three-dimensional view of the hydraulic actuator  10 , whereas  FIG. 2  shows a top view of the same actuator  10 . In this embodiment, the housing  12  encloses the device with the aid of a front end cap  14  and a back end cap  16 . It is preferred that the housing  12  and the front end cap  14  and the back end cap  16  be constructed from any rigid material which can be cast, molded, milled, or other manufacturing process which can put the device in proper form.  
         [0052]     This embodiment of the hydraulic actuator assembly  10  shows two arms  18  extending out beyond the housing  12 . When the hydraulic actuator assembly  10  is operated, the arms  18  pivot in a back and forth motion. The actuator assembly  10  can be configured with one or more of the arms  18 . When two or more arms  18  are used on a single actuator  10 , the device can be used for grabbing or grappling items.  
         [0053]      FIGS. 3, 4  and  5  show a cut-away version of one embodiment of the hydraulic actuator assembly.  FIG. 3  shows the arms  18  in a not-rotated position.  FIG. 4  shows the arms  18  fully rotated.  FIG. 5  shows the arms  18  half way through the rotation.  FIG. 5A  shows an enlarged view of the oil channel  40 .  
         [0054]     The rack  32  is operatively connected or otherwise affixed to the rack gland  34 . This assembly moves in a linear motion within the housing  12 .  
         [0055]     The motion of the rack  32  and rack gland  34  assembly is created when a pressurizing fluid, such as hydraulic fluid, is pushed through the oil tube  20  which is located through the back end cap  16 . Once the pressurizing fluid flows through the oil tube  20  it enters the small area oil chamber  24  and applies a pressure against the small gland surface  36 . The force of the pressurizing fluid flowing into the small area oil chamber  24  is greater than the force of a fluid in the large area oil chamber  26 . This pressure causes the rack  32  and rack gland  34  to move away from the pressure created in the small area oil chamber  24 . This movement displaces the existing fluid in the large oil chamber  26  out through the oil tube  22  in the front end cap  14 . The pressure fluid within the small area oil chamber  24  and the large area oil chamber  26  is contained within these chambers  24  and  26  by the use of seals  30 , and  28  and O-ring  88 . Additional seals may be necessary if parts are made in multiple pieces. For example, the front cap  14  and the back cap  16  can be created from multiple pieces instead of a single piece. Therefore seals are needed between the pieces to prevent leakage where the multiple parts join together.  
         [0056]     When the rack  32  and rack gland  34  move linearly within the housing  12 , teeth on the rack  32  engage teeth on the gears  50 . The farther the rack  32  moves the more the gears  50  are rotated about an axis created by bearings  52 . This, in turn, causes the arms  18 , which are connected to the gears  50 , to rotate.  
         [0057]     The rack  32  and rack gland assembly  34  move in an opposite direction within the housing  12  when pressurizing fluid which is of a greater force flows through the oil tube  22  and into the large area oil chamber  26  and applies pressure against the large gland surface  38 . This displaces the rack  32  and rack gland  34  assembly to push the fluid which is applying pressure to the small gland surface  36  in the small area oil chamber  24  out through the oil tube  20 . The displacement of the rack  32  again causes the gears  50  to rotate in an opposite direction. This, in turn, causes the arms  18  to rotate in an opposite direction.  
         [0058]     The preferred shape of the rack gland  34  for this embodiment of the invention can be seen in the expanded view drawing of  FIG. 6 . It is preferred that the rack gland  34  be a hollow cylindrical tube closed on one end and open on the other with a rack gland lip  42  extending from the cylinder around the outside of the open end of the rack gland  34 . However, any shape which creates a longitudinal annular member is acceptable. Additionally, the rack gland  34  can be made from multiple pieces.  
         [0059]     The shape of the rack gland  34  allows the rack assembly  60  to nest inside of the front end cap  14  and the back end cap  16 . In addition, the pressurizing fluid can flow in the oil channel  40  between the front end cap  14  and the rack gland  34  thereby also creating pressure on the rack gland lip  42  at the large gland surface area  38 .  
         [0060]     It is commonly known in hydraulics that the larger the surface area the larger the force which can be created by a pressurizing fluid exerting pressure on the surface area. Thus, with the rack gland  34  of the current invention which has a small gland surface area  36  and a large gland surface area  38  nested within one another a smaller force can be created forcing the rack gland  34  in one direction using the small gland surface area  36  and a larger force can be developed using pressurizing fluid against the large gland surface  38 . The surface areas of the two surfaces  36 ,  38  are different. It is a greater force caused by the pressure acting on the working area which causes a net force in one direction or the other. For example, the working surface area for the large gland surface  38  can be 9.621 in 2  (based on 3.5″ diameter) and the working surface area for the small gland surface  36  can be 2.405 in 2  (based on 1.75″ diameter). This is an area ratio of 4:1. Therefore, a pressure of 1000 psi on the large gland surface  38  is a force of 9621 lb., but a pressure of 1500 psi on the small gland surface  36  is 3608 lb. The pressure is higher on the small size, but more force on the large side creates a net force in that direction. However, any dimensions can be used to vary forces.  
         [0061]     This hydraulic actuator assembly  10  can be created within a considerably smaller axial length than prior hydraulic actuators creating bi-directional motion because the pressure surface areas  36  and  38  nest within one another. In addition, this embodiment of the current invention allows for all of the hydraulic moving parts to be located within the housing  12 , with the one exception being a portion of the gear  50  extending beyond the housing  12 . This creates a much more durable product which can be used in harsh environments. In addition, the enclosed housing design of the current invention allows for lubricating fluid to be within the housing. This lubricates the gears, bearings and etc. which prolongs the life of the actuator.  
         [0062]     Again looking to  FIG. 6 , we see the expanded view of one embodiment of the current invention. The rack assembly  60  is shown with the above-mentioned parts plus an O-ring  88  which is used to prevent leakage of the pressurizing fluid. Depending on the pressures to be developed, an additional back-up ring  86  can be used with the current invention.  
         [0063]     This embodiment of the invention shows two arm assemblies  62  which attach to the gears  50 . However, any type of mechanical device can be connected to the gears  50  for rotating. The jam nut  70  holds the arm  18  firmly to the gear  50 . Additionally, a bearing  72  and tang  74  mount to the arm  18  and give strength to the arm assembly  62  for rotating on the bearings  72  and the gear bearings  52 . Furthermore, the bearing cap  76  and locking cap  82  function to hold in the bearings  50  within the housing  12  and allow the bearings  50  to rotate or pivot within the housing  12 . The O-rings  84  and the O-ring  78  and pin seal  80  are used to keep the invention from leaking lubricating fluid outside of the housing  12 .  
         [0064]     The hydraulic actuator of the current invention can be used for creating both linear motion along the same plane as the piston/gland assembly  60 , extending outside of the housing through the housing  12  and/or front cap  14 , and/or the back cap  16 , or rotational motion about the bearings  52 . This suits the hydraulic actuator of the current invention well for many applications.  
         [0065]     A few examples of applications for the current invention are shown in  FIGS. 7, 8  and  9 . However, numerous other applications of the current invention are available and should not be limited in any way by the given examples. For example, hydraulic actuator assembly  10  is shown configured with both two arm  110  and four arm  100  assembly configurations. However, any number of armed assemblies  62  can be used with the current invention. Additionally, the hydraulic actuator assembly  10  of the current invention can be used on any type of application. The hydraulic actuator assembly  10  is shown being used on vehicles, however, the hydraulic actuator assembly  10  can be used on apparatuses other than vehicles. As an example, the hydraulic actuator assembly  10  can be used on parts handling equipment, waste crushing equipment, or any other type of equipment.  
         [0066]      FIGS. 7A through 7E  show exemplary four-arm grabber assemblies  100 . These assemblies  100  have grabber arms  102  which connect to the arm assembly  62  of the hydraulic actuator assembly  10 . The four-arm grabber assembly  100  can then be connected to the vehicle or machine with connecting structure arms  104 .  
         [0067]      FIG. 7A  shows a four-arm grabber assembly  100  in an open position.  FIG. 7B  shows the same four-arm grabber assembly  100  in a closed position.  FIG. 7C  shows an exemplary four-arm grabber vehicle  106  utilizing the four-arm grabber assembly  100 . Similarly,  FIG. 7D  shows a four-arm grabber assembly  100  in a closed position which can be attached to a four-arm grabber vehicle  106 .  
         [0068]     Another example of a four-arm grabber vehicle  108  is shown in  FIG. 7E .  
         [0069]     Embodiments of the two-arm grabber assembly  110  are shown in  FIGS. 8A  through  8 C. For the two-arm grabber assembly  110  two grabber arms  112  are operatively connected to the arm assemblies  62  of the hydraulic actuator assembly  10 . The two-arm grabber assembly  110  can then be connected to a machine or vehicle by the use of the connecting structure arms  104 .  
         [0070]      FIGS. 8B and 8C  show a side and top view respectively of one embodiment of a vehicle  114  utilizing the two-arm grabber assembly  110 .  
         [0071]     One embodiment of a clam shell grabber assembly  120  is shown in  FIG. 9A . Here, the clam shell grabber assembly  120  comprises two clam shell bucket halves  122  operatively connected to the arm assemblies  62  of the hydraulic actuator assembly  10 . The clam shell grabber assembly  120  can then be connected to a machine or vehicle by connecting structure arms  104 .  
         [0072]      FIG. 9B  shows one embodiment of an exemplary clam shell bucket vehicle  124  utilizing the clam shell grabber assembly  120 . The clam shell grabber assembly  120  for use on the exemplary clam shell bucket vehicle  124  is shown in  FIG. 9C  in the closed position.  
         [0073]     The hydraulic actuator assembly  10  of the current invention as shown and discussed above can be used in many different applications. The hydraulic actuator assembly  10  can be incorporated into stationary equipment, mobile equipment, vehicles, or any other application.  
         [0074]     The benefits of the current invention over the prior art are many. However, a couple of noteworthy benefits are the fact that dual motion hydraulics can be created in a much smaller linear distance over the prior art.  
         [0075]     Another major benefit of the current invention over the prior art is the fact that the hydraulic moving parts are contained within a housing. This significantly reduces opportunities for dust, dirt, grease, and etc. from damaging the operation of the hydraulic actuator assembly.  
         [0076]     Another benefit of the current invention is that when used for grabbing or grappling applications it creates relatively constant torque throughout the range of motion. Other typical grabbing mechanisms use cylinders to push and pull the arms in and out and the torque is not constant through the motion. This more constant torque feature allows for more precise control during grabbing functions.  
         [0077]     The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.