Abstract:
A hydraulic jack including a frame and a pump connected to the frame. The pump includes a rod, a housing, a piston and a plurality of valves. The rod has a cross-sectional area. The housing has an end through which the rod slides. The piston is associated with said rod, with the piston establishing a rod side chamber and a piston side chamber within the housing. The piston having a cross-sectional area. The plurality of valves each are fluidly connected to the rod side chamber and/or the piston side chamber. The piston, the rod and the valves are arranged to provide a first hydraulic fluid flow associated with the cross-sectional area of the piston until a predetermined pressure is reached and a second hydraulic fluid flow associated with the cross-sectional area of the rod after the predetermined pressure is reached.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a hydraulic pumping cylinder, and, more particularly, to a low-load rapid fluid movement pumping cylinder. 
   2. Description of the Related Art 
   Hydraulic cylinders are common devices used in industry and for the jacking of loads using a jacking mechanism having a input cylinder and an output cylinder. The output cylinder is used to lift the load to a predetermined height with a considerably small force utilized on the mechanical portion that moves the input cylinder. The working principal of the hydraulic jack system provides for an applied small force that moves the input piston of a small cross-sectional area and pushes the hydraulic fluid or oil into an output cylinder, which then forces an output piston of large cross-sectional area to jack up a load. 
   The path of the input piston is often far longer than that of the output piston. The input piston must be repeatedly pumped to jack a load to a predetermined position. During the jacking process, each stroke of the input piston moves the output piston based upon the fluid transfer from the input cylinder to the output cylinder. Typically the same number of pumping strokes is needed to move the jack to a predetermined height regardless of whether there is a load on the output cylinder or not. Under the no-load condition the rate at which the ram of the output cylinder extends, directly or by way of a lifting arm, is not noticeably changed from the rate at which it travels under a loaded condition. 
   A disadvantage of the systems presently in use is that time and energy are wasted in moving the output piston/ram to the desired location or to encounter a load which is to be moved and/or lifted. Solutions utilized prior to the present invention typically utilize many hydraulic components, which are complex and expensive to manufacture, and due to the additional number of parts are often unreliable. 
   What is needed in the art is an easy to operate and inexpensive to manufacture pumping cylinder system that moves a large quantity of hydraulic fluid under low pressure yet delivering high pressure when a load is encountered. 
   SUMMARY OF THE INVENTION 
   The present invention provides a hydraulic pumping cylinder. 
   The invention in one form is directed to hydraulic jack including a frame and a pump connected to the frame. The pump includes a rod, a housing, a piston and a plurality of valves. The rod has a cross-sectional area. The housing has an end through which the rod slides. The piston is associated with said rod, with the piston establishing a rod side chamber and a piston side chamber within the housing. The piston having a cross-sectional area. The plurality of valves each are fluidly connected to the rod side chamber and/or the piston side chamber. The piston, the rod and the valves are arranged to provide a first hydraulic fluid flow associated with the cross-sectional area of the piston until a predetermined pressure is reached and a second hydraulic fluid flow associated with the cross-sectional area of the rod after the predetermined pressure is reached. 
   An advantage of the present invention is that under a no-load or near no-load condition the pumping piston moves a large volume of hydraulic fluid as compared to when the fluid is under a high pressure resistance. 
   Another advantage of the present invention is that an output cylinder is rapidly moved under a no-load condition to thereby allow the output cylinder to rapidly engage a load to undertake the necessary work. 
   Yet another advantage of the present invention is that the apparatus is inexpensive to manufacture and can be readily adapted into systems currently using prior art designs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  illustrates an application of an embodiment of the present invention in the form of a manually operated hydraulic jack; 
       FIG. 2  is a partially schematicized and cross-sectional view of one embodiment of the present invention; 
       FIG. 3  is another partially schematicized and partially cross-sectional view of another embodiment of the present invention; 
       FIG. 4  is yet another partially schematicized and partially cross-sectional view of another embodiment of the present invention; 
       FIG. 5  is still yet another partially schematicized and partially cross-sectional view of another embodiment of the present invention; 
       FIG. 6  is a further partially schematicized and partially cross-sectional view of another embodiment of the present invention; and 
       FIG. 7  is another partially schematicized and partially cross-sectional view of yet another embodiment of the present invention. 
   

   Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a hydraulic jack  10  having a frame  12 , a handle  14  and a hydraulic pump  16 . Hydraulic jack  10  is similar on the exterior to numerous jack systems currently in use. Jack  10  is rolled under a device, such as a vehicle, and it is positioned so that the lifting arm will engage a portion of the underside of the car. Handle  14  is pumped up and down to actuate hydraulic pump  16 , which is hydraulically linked to an output cylinder, not shown, that extends the lifting arm for the purpose of jacking the load, such as the vehicle. Hydraulic jack  10  may utilize any one of the embodiments to be described hereinafter as a hydraulic pump  16 . 
   Now, additionally referring to  FIG. 2  there is shown a hydraulic pump  16  that includes connections to a reservoir  18 , a valve  20 , check valves  22 ,  24  and  26 , a shaft  28 , a housing  30 , a retainer  32 , a retainer  34 , a spring  36 , a piston  38 , that operates within housing  30  having chambers  40  and  42  defined by the relative position of piston  38 . Chamber  40  is herein referred to as a rod side or shaft side of the assembly and chamber  42  is herein referred to as a piston side of the assembly even though in some of the embodiments shaft  28  will, during its operation, extend in to chamber  42 . Reservoir  18  holds hydraulic fluid that is pumped by way of hydraulic pump  16  to a working cylinder, not shown. Reservoir  18  may be vented to the air and allows a fluid flow into and out of reservoir  18  as directed by actions carried out by the positioning of valve  20  and pumping on handle  14 . Valve  20  may be manually operated or under the control of an automatic control system. Valve  20  is opened to allow fluid flow from the work cylinder back into reservoir  18 . Typically the fluid in the work cylinder, when it is under a load, is under pressure that has been built up by the operation of hydraulic pump  16 . 
   Check valves  22 ,  24  and  26  allow for fluid to enter into housing  30  at appropriate times and to exit in a pressurized manner through check valve  26  to the work cylinder. Check valves  22 ,  24  and  26  may be spring biased to allow fluid flow through only in one direction. 
   Shaft  28 , also known as a rod  28 , is connected either directly to handle  14  or by way of a leveraging method utilized by those familiar with the art. Shaft  28  is hydraulically sealed where it enters into housing  30  and shaft  28  is slidingly engaged with housing  30  allowing shaft  28  to enter and exit in a longitudinal direction of shaft  28 . Hydraulic lines are shown schematically entering through portions of housing  30  and may be appropriately positioned along end portions of housing  30  or along the sides thereof. The actually positioning of the hydraulic lines is not limited by the positions shown in the figures and their positions are merely for the ease of illustration and explanation of the present invention. 
   Connected to shaft  28  are retainers  32  and  34  which limit the movement of piston  38  along shaft  28  within housing  30 . Retainers  32  and  34  may be a snap ring or other removable feature. Alternatively, at least one of retainers  32  and  34  may be an integral part of shaft  28 . Spring  36  provides a biasing between retainer  32  and piston  38 . Piston  38  is slidable along the interior walls of housing  30  and is also slidable along shaft  28 , at least within the constraints of retainers  32  and  34 . The shape of piston  38  corresponds to the interior shape of housing  30 , which is typically a cylindrical shape, although other shapes are also possible. In a similar fashion shaft  28  is typically of a cylindrical nature although other shapes are also contemplated. 
   In operation of pumping piston  16 , a shaft  28  is withdrawn completely to the left so that retainer  32  is against the inner housing wall of housing  30 . In this position chamber  40  is much smaller than chamber  42 . Force is applied to shaft  28  pushing it further into housing  30 , presuming initially that the work cylinder has not encountered a load, the biasing force of spring  36  causes piston  38  to advance with shaft  28  with piston  38  proximate to or against retainer  34 . As shaft  28  continues to move into housing  30 . chamber  40  increases in size causing fluid to travel from reservoir  18  through check valve  22  into chamber  40 . Fluid in chamber  42  is forced through the hydraulic line and through check valve  26  and is sent to the work cylinder. This cycle can be repeated with shaft  28  being moved longitudinally into and out of housing  30  causing large transfers of fluid to the work cylinder. When shaft  28  is moved out of housing  30 , check valve  26  is closed and check valves  24  and  22  are open to allow for transfer of fluid into chamber  42 . When shaft  28  is being moved out from housing  30  a large amount of hydraulic fluid is transferred from chamber  40  to chamber  42 . The hydraulic fluid is introduced through check valve  22  since the overall displacement within housing  30  is being reduced since shaft  28  is being removed through the wall of housing  30 . 
   When the work cylinder encounters a load, pressure in the line increases and as shaft  28  is further inserted into housing  30  the pressure in chamber  42  is such that piston  38  does not travel with shaft  28  and will instead slide along shaft  28  as shaft  28  is entering into housing  30 . As shaft  28  continues to enter into housing  30 , spring  36  may compress as piston  38  moves in the direction of shaft  28 , but at a reduced rate in direction that shaft  28  is moving. Piston  38  moves along shaft  28 . Check valve  26  will open to receive pressurized fluid from chamber  42 . In this manner the movement of shaft  28  displaces a smaller amount of fluid when piston  38  stops tracking the movement of shaft  28 , thereby providing for two different pumping volumes when shaft  28  is moved. The volume of fluid moved is based on the relative cross-sectional area of shaft  28  versus the cross-sectional area of piston  38  and shaft  28  when they are moving together. 
   Now, additionally referring to  FIG. 3  there is illustrated working piston  116  with some components that are the same as those described in the previous example, and some of the components that are similar but not identical to the previous embodiment being illustrated with a number that is one hundred higher than that illustrated in the previous figure. In this illustration a shaft  128  includes a passageway  150  that extends through a side of the shaft to the end of the shaft having a check valve  124  optionally positioned in passageway  150 . Passageway  150  and check valve  124  are illustrated schematically and may be implemented in numerous ways and there may exist more than one passageway that extends through an interior portion of shaft  128 . The operation of this embodiment is substantially similar to that previously described with some depth in the previous description. The positioning of check valve  124  in shaft  128  thereby precludes the need for a check valve  24  external to housing  30 . It is also possible that check valve  124  may be eliminated or may consist of a flapping mechanism possibly on the end of shaft  128 . 
   Now, additionally referring to  FIG. 4 , there is illustrated yet another embodiment of the present invention again having certain portions with the two least significant digits remaining the same for similar parts used in the previous embodiments. Pumping cylinder  216  has a shaft  228  that has passageways  254  and  256 . Passageways  252  are positioned in piston  238 . In this embodiment when shaft  228  is positioned such that piston  238  is positioned between retainer  34  and passageway  254  that piston  238  will have a tendency to follow along with shaft  228  because fluid can flow through passageway  256  and  254  to substantially equalize the pressure in chambers  40  and  42 . When high pressure is encountered by way of a load applied to the working cylinder, piston  238  no longer travels with shaft  228  and the displacement of shaft  228  as it enters housing  30  serves as the high pressure transfer of fluid through check vale  26  to the working cylinder. Piston  238  floats along shaft  228  within housing  30  and it is the displacement of fluid by the entry of shaft  228  into housing  30  that accounts for the pressurized exit of fluid by way of check valve  26 . As shaft  228  is withdrawn from housing  30  pickup fluid enters by way of check valve  22  and piston  238  may even travel counter to a direction of shaft  228  until passageways  252  align with passageway  254  to allow fluid then to flow from chamber  40  to chamber  42 . 
   Now, additionally referring to  FIG. 5 , there is illustrated a hydraulic pump  316  again having certain elements with the two least significant digits remaining the same for similar parts used in the previous embodiments. Shaft  328  enters into housing  30  and has grooves  358  and  360  along a portion of the length of shaft  328 . Grooves  358  and  360  allow for fluid to pass from chamber  40  to chamber  42  and vice-versa based upon the positioning of grooves  358  and  360  relative to piston  338 . When the portion of piston  338  that slides along shaft  328  is positioned so that it covers one end of groove  358  and one end of groove  360  and that particular position oil does not transfer between chambers  40  and  42  except perhaps a small amount due to leakage of the seals. In this position piston  338  will travel along with shaft  328  as it is moved in housing  30 . Retainers  32  and  34  prevent piston  338  from disengaging with shaft  328  yet allows piston  338  to be in sliding contact with the surface of shaft  328 . One end of groove  358  is positioned close to retainer  32  and the other end of groove  358  is positioned closer to retainer  34  than one end of groove  360 . Although only one groove  358  is illustrated, more than one groove  358  may be positioned around the outer portion of shaft  328 . Further, the length of overlap grooves  358  and  360  may not all be identical to each other. Once high pressure is encountered due to a load on the working cylinder, shaft  328  slides through piston  338  with the hydraulic fluid in chambers  40  and  42  being in communication by way of groove  358  as shaft  328  continues to move into housing  30 . In this way high pressure fluid can be forced through check valve  26  to the working cylinder. When shaft  328  is being withdrawn from housing  30  piston  338  moves close to retainer  34  and makeup fluid is introduced by way of check valve  22  with the fluid flowing from chamber  40  into chamber  42  by way of grooves  360 . 
   Various configurations utilizing biasing members such as a spring  36  are contemplated with even the possibility of more than one spring  36  having different biasing characteristics. The length of grooves, passageways positioning of retainer have been illustrated for the ease of illustration and explanation and are not determinative relative to their position, length or size in the actual manufacture of the pumping cylinder. Further, the relative sizes of the sliding piston and cross-sectional area of the shaft along with the size of housing  30  are simply for the ease of illustration and are not considered determinative of the final application. 
   Now, additionally referring to  FIG. 6 , there is illustrated a hydraulic pump  416  again having certain elements with the two least significant digits remaining the same for similar parts used in the previous embodiments. Shaft  428  enters into housing  30  and piston  438  is connected to an end of shaft  428 . Regarding the external elements illustrated that have the same numbers as those illustrated in  FIG. 2 , the descriptions above apply here as well. Preloaded valve  402  precludes flow therethrough from the side connected to chamber  40  to the side connected to chamber  42 . Preloaded valve  402  allows a flow therethrough from the side connected to chamber  42  to the side connected to chamber  40 , once a predetermined differential pressure is exceeded. In this way the fluid supplied from chamber  42  to the working cylinder is of a high volume as long as the pressure is below the predetermined pressure. Once the pressure exceeds the predetermined value, which can be caused by the lifting arm contacting a load, then valve  402  allows a flow of fluid from chamber  42  to chamber  40 . The fluid that is equivalent to the fluid displaced by the entrance of shaft  428  into chamber  40  is sent to the working cylinder at a higher pressure/lower volume since in this mode the effective cross-sectional area of pump  416  is the cross-sectional area of shaft  428 . This very effectively produces a dual pressure pump. 
   Now, additionally referring to  FIG. 7 , there is illustrated a hydraulic pump  516  again having certain elements with the two least significant digits remaining the same for similar parts used in the previous embodiments. Shaft  528  enters into housing  30  and piston  538  is connected to an end of shaft  528 . Regarding the external elements illustrated that have the same numbers as those illustrated in  FIG. 2 , the descriptions above apply here as well. Preloaded valve  502  precludes flow therethrough from the side connected to chamber  40  to the side connected to chamber  42 . Preloaded valve  502  allows a flow therethrough from the side connected to chamber  42  to the side connected to chamber  40 , once a predetermined differential pressure is exceeded. In this way the fluid supplied from chamber  42  to the working cylinder is of a high volume as long as the pressure is below the predetermined pressure. Once the pressure exceeds the predetermined value, which can be caused by the lifting arm of the jack contacting a load, then valve  502  allows a flow of fluid from chamber  42  to chamber  40 . The fluid that is equivalent to the fluid displaced by the entrance of shaft  528  into chamber  40  is sent to the working cylinder at a higher pressure/lower volume since in this mode the effective cross-sectional area of pump  516  is the cross-sectional area of shaft  528 . While valve  502  is depicted as providing a fluid flow from the center of piston  538  through a portion of shaft  528  and out the side of shaft  528 , it is also contemplated that the same function can be implemented if valve  502  were located in piston  538  exclusively. 
   While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.