Abstract:
A multi-purpose hydraulic tool of the open center and closed center type is provided with an OC/CC knob mounted on the trigger activated spool. The spool has a knob which can be turned to easily move between OC and CC operating conditions, without the use of additional tools. A check spool assembly works in conjunction with spool assembly in the open-center condition to provide for release of oil at the end of the return stroke. Adapters are provided so that crimping heads can be easily interchanged.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     This invention relates to hydraulic hand tools, and more particularly, to a hydraulic tool that can use a constant pressure fluid delivery system or a constant volume fluid delivery system. In particular, this invention relates to a hydraulic tool having a selector switch to operate the tool in an “open center” (OC) mode or a “closed center” (CC) mode.  
         [0003]     2. Description of the Prior Art  
         [0004]     Hand held hydraulic tools capable of operating by two different modes of operation known as constant volume and constant pressure are disclosed in the prior art such as U.S. Pat. No. 4,366,673, issued Jan. 4, 1983 to Lapp. That patent shows an apparatus having a valve body with a pressure port  25  and a return port  26 , a cross port  31  and a tubular conduit  72 , a valve spool  45 , and a selector member  63  in which the plug  63  enables the valve  45  to be converted so that the amplifier  13  may be used with either an open center or a closed center pump system (see column 4, line 54).  
         [0005]     A closed-open center hydraulic valve assembly is shown in U.S. No. 3,882,883, issued May 13, 1975 to Droegemueller.  
         [0006]     The term “constant volume” refers to the fact that there is an open center spool valve. In such an arrangement, oil flows back to the source through the spool in what is known as the neutral or off position.  
         [0007]     In a constant pressure tool, a closed center spool prevents the oil from flowing back, thereby maintaining the pressure.  
         [0008]     U.S. Pat. No. 5,442,992, issued Aug. 22, 1995 to Sanner, et al., discloses a hydraulic tool which has a rotatable selector  60 ,  FIG. 1 . In the constant volume (OC) mode, fluid flows on the back side of the piston and around the piston through a passage  62  having a check valve therein permitting fluid flow in only one direction from a cross-port  52  to the opposite end of the tubular conduit.  
         [0009]     U.S. Pat. No. 6,490,962, issued Dec. 10, 2002 to Schultz, discloses a hydraulic tool in which a selector sleeve  5  may be moved so that oil can pass through a hole  12  in the tube  6  which is coincident with a hole  9   a  in a sleeve valve  9  in the constant volume (OC) mode neutral position, as shown in  FIG. 3 . In order to move this sleeve, it is necessary in practice to back off a set screw (shown in the Figure but not identified in the description of the patent specification), so that two portions butt up against one another and the spring  13  is compressed. This selector sleeve provides for switching between the OC and CC modes.  
         [0010]     This patent shows, discloses and claims a hydraulic tool adjustable between two modes of operation. One mode is known as the open center mode, or constant volume mode; and the other mode is known as a closed center mode, or constant pressure mode. Each mode has both a neutral position and a work position.  
         [0011]     The constant pressure neutral position is shown in  FIG. 1  wherein pressurized fluid travels through a tube into a retract chamber.  
         [0012]     When the trigger  20  is squeezed, the configuration is as in  FIG. 2 . This is the working position when the hydraulic fluid flows into a drive chamber  4  causing the piston  2  to move to the left, and exhausting fluid which was in the retract chamber  3  to exhaust through the central tube out an exit port  15 .  
         [0013]     In the constant volume mode, the neutral position is shown in  FIG. 3  wherein fluid passes through a central tube  6  and into the retract chamber  3 . At the same time, the excess fluid exits through a small hole  12  between the ends of the tube  6  and then out through the exit port before ever reaching the drive chamber  4 .  
         [0014]     When the trigger is pulled, the working position is as shown in  FIG. 4  which is identical to the working position in  FIG. 2 , that is, the fluid passes directly into the drive chamber. In this mode, fluid exits just as it did in  FIG. 2  down the inner tube and out the exit port  15  from the retract chamber.  
         [0015]     U.S. Pat. No. 5,778,755, issued Jul. 14, 1998 to Boese, also discloses a hand-held and operated hydraulic tool with a control valve having a sensor switchable between an open end and closed condition. The adjustment assembly provides a structure which can be configured to force open shuttle spool valves in the control apparatus in a neutral condition for use with a constant volume power supply. The adjustment assembly can also be configured to be disengaged from the shuttle spool valves in a neutral condition for use on a constant pressure hydraulic power system.  
       DISCLOSURE OF THE INVENTION  
     SUMMARY OF THE INVENTION  
       [0016]     I have invented a multi-purpose hydraulic tool of the open center and closed center type having a trigger actuated spool means having a trigger and a spool, and a knob mounted on the spool to rotate the spool between open center and closed center conditions.  
         [0017]     The knob has easily recognizable indicia to apprise field personnel of the operating conditions, that is, the open-center (OC) and closed-center (CC) conditions. The knob may be rotated to “0” (OC) or “C” (CC) by hand without any additional tools.  
         [0018]     The tool has a ram and an adapter means for operative engagement with the ram. The adapter means provides a means for mounting a prior art crimping tool, such as a die. A number of different adapter means are provided to accommodate various prior art tools. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0019]      FIG. 1  is a longitudinal sectional view of a tool in accordance with my invention;  
         [0020]      FIG. 2  is a longitudinal sectional view of a tool in accordance with my invention shown in an alternate position;  
         [0021]      FIG. 3  is a rear sectional view of a tool in accordance with my invention;  
         [0022]      FIG. 4  is a rear sectional view of a device in accordance with my invention shown in an alternate position;  
         [0023]      FIG. 5  is an enlarged sectional view taken along the lines and arrows  5 - 5  in  FIG. 4 , of a portion of a device in accordance with my invention;  
         [0024]      FIG. 6  is an enlarged sectional view similar to  FIG. 5 , of a portion of a device in accordance with my invention, shown in an alternate position;  
         [0025]      FIG. 7  is a perspective view of a portion of a device in accordance with my invention;  
         [0026]      FIG. 8  is a view taken as indicated by the lines and arrows  8 - 8  in  FIG. 2  of a portion of a device in accordance with my invention;  
         [0027]      FIG. 9  is a perspective view of a portion of a device in accordance with my invention; and  
         [0028]      FIG. 10  is a perspective view of a portion of a device in accordance with my invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     Referring to the Figures,  FIG. 1  shows a section of a hydraulic tool in accordance with the preferred embodiment of my invention. The tool has a handle body  14  to which a trigger  10  is pivotally mounted at  100 . A spool  13 , configured for open center and closed center conditions of operation, is mounted transversely in the handle body. The spool is retained in the handle body by snap rings and washers  102 ,  104  at both ends. At one end, a portion  106  of the spool extends from the handle body to engage the trigger  10 . This portion may be made as a separate part which is screwed into the other part of the spool. An “O” ring seal is provided at  107 . At the other end of the spool, a spring  108  engages a shoulder on the spool and is compressed to exert a force on the spool and maintain it in engagement with the handle. In  FIG. 1 , the trigger  10  is shown depressed inwardly toward the handle, so as to fully compress the spring  108 . “O” ring seals are provided at  109  and  111  between the spool and the handle body. The piston  12  is shown in  FIG. 1  near its fully advanced position.  
         [0030]      FIG. 2  shows the handle  10  released. The spring  108  is expanded pushing against the spool and forcing end  106  to exert a force against the handle to fully release the trigger. The piston  12  is near the retracted position.  
         [0031]     In both views the solid dark arrows “A” show the path of the pressurized oil driving the ram  26 — forward in view  1 , backward in view  2 . The dotted dark arrows “B” show the path of the oil returning to the source (not shown; but well known in the art) from the opposite side of the piston  12 .  
         [0032]     When the trigger is depressed oil is directed over the spool  13  to the cylinder area  15  directly behind the piston  12 . The oil in front of the piston is forced out through a non-moving center tube  16  running through the center of the piston—similar to most common double acting piston assemblies of this type.  
         [0033]     When the trigger is released ( FIG. 2 ) the pressurized oil is then directed through the center tube  16  and enters the cylinder area  11  above the piston through a hole  17  in the side of the piston; and generates force in the return direction. The oil behind the piston evacuates the cylinder area through the hole  18  leading to the trigger spool. The exiting oil then enters a hole  19  in the side of the spool  13 , passes through the center of the spool  13 , and exits directly above the open return port  20 .  
         [0034]     The operating condition shown in  FIGS. 1 and 2  is known as constant volume and the spool is shown in the open center condition. In that position in  FIG. 2 , oil is permitted to circulate through the tool.  
         [0035]     Referring to  FIGS. 1 and 2 , the cylinder  22  housing the piston is preferably made of aluminum. An “O” ring  23  is disposed around the periphery of the piston to provide a seal with the inner wall of the cylinder. A nosepiece  24  is threaded onto the end of the cylinder. As pressure builds in the cylinder, it expands, thereby tightening, that is, enhancing the strength of the threaded engagement with the nosepiece.  
         [0036]     The nose piece has an externally threaded end  25  to accept different configurations of tool heads (not shown, but well known in the art).  
         [0037]     The piston has a ram  26 ; either threaded onto it or as part of a unitary assembly, as shown in the figures. The ram has internal threads  27  to accept adapters for the required parts for the different heads (aforesaid). These adapters are shown in greater detail in  FIGS. 9 and 10 ; and comprise configurations for known prior art cradles for holding crimping tools and dies. I have designed these adapters  54  and  63  with threaded bosses  53  for engagement with the threads  27  of the ram.  
         [0038]      FIG. 9  shows an adapter  63  for a prior art U-die. The cylindrical adapter  63  has a cradle  64  for the U-die; which die (not shown) is held in place by a spring loaded button  65  and pin  66  arrangement (not shown in detail; but well known in the art).  
         [0039]     The cylindrical adapter  54  has a bore  55  for a prior art tool, such as, a Kearney die; which die (not shown) is held in place by a set screw  56  (not shown in detail; but well known in the art).  
         [0040]     The interchangeability of crimping heads and dies is unique in the industry.  
         [0041]     If a crimping tool is used, a crimp would be made on full extension of the piston and ram  26 . Then the operator would let go of the trigger  10 . The spring would then drive the spool to the left when viewed in  FIG. 1  to the position shown in  FIG. 2 . While the tool is working, one does not want constant volume conditions until the piston returns completely.  
         [0042]     Referring to  FIGS. 3 and 4  a check spool assembly means  33  is shown in section. This assembly means controls the flow of oil through the tool. It is mounted in the handle body  14 . It comprises a spring loaded plunger means  37  and a check valve means  34 . The force of the spring  35  on the check valve base  36 , forces the plunger  38  to extend into the cylinder area  15  when the piston is in the extended position. As the piston  12  is retracted, it engages the end of the plunger  38  and forces the plunger back into its housing in the handle body  14 .  
         [0043]     A by-pass passageway  31  is located below the center tube  16 . This passageway leads to the two-stage check spool assembly means  33 ,  FIG. 3 . The check spool assembly means  33  is not visible in  FIG. 1  or  2  as it is directly behind the center tube. The check spool assemble means further comprises a plunger means  37  with two cross holes  39  and passage  51  for fluid flow communication with the passageway  31 . When the plunger means  37  is pushed in sufficiently, oil then flows into the passageway  51  and forces the ball  52  off of its seat and thus opens the check valve (see  FIG. 4 ). Slots  57  in the base  36  allow oil to escape from the check spool assembly means and continue into passageway  61 ,  FIG. 5 .  
         [0044]     In operation, when the piston  12  is in the advanced position, the check valve means  34  prevents oil from entering the passageway  51 . When the trigger is released, the oil in passageway  31  is prevented from entering the passageway  51  because the cross holes of the passageway  51  are not lined up with the passageway  31 .  
         [0045]     When the piston  12  is fully retracted, oil is permitted to flow through the check valve means and into passageway  61 ,  FIG. 5 . With the spool  13  set to the open-center position, oil flows through the passageway  61  and around a notch  62  in the spool  13  and into a chamber  20  which communicates with the outlet port of the tool. Therefore, right at the end of the travel it releases all of the oil.  
         [0046]     If the source of the oil under pressure is constant volume, then the tool is set to OC.  
         [0047]     When the correct conditions exist, oil will be allowed to circulate through the tool to satisfy the open-center pump condition while simultaneously maintaining pressure on the piston in the reverse direction. The conditions are: 
        1. The OC/CC knob must be turned to the “0” (OC) position;     2. The trigger must be released; and     3. The piston must be fully retracted, depressing the check spool assembly means.        
 
         [0051]     When these conditions exist, as shown in  FIG. 4 , the oil flow will stop in the center tube  16 , but will continue to circulate through the handle body  14 .  
         [0052]     In  FIG. 3  the piston is advanced and no oil may flow through the check spool assembly.  
         [0053]      FIG. 4  shows the piston retracted and depressing the check spool assembly means allowing oil to flow from bypass hole  31 , into the check spool assembly means through port  51 , pushing open check ball  52 , and return to the spool chamber via passageway  61 . The check ball assembly means prevents oil from flowing in the wrong direction when the trigger is depressed and the piston is still in the retracted position. The ball  52  also generates upward pressure on the assembly forcing it into the correct position as the piston advances when the trigger is depressed.  
         [0054]     A pressure regulator  70  is provided mounted in a hole  71  in the handle body  14  and in fluid flow communication with the inlet and outlet to regulate the oil pressure in the tool; in a manner well known in the art.  
         [0055]     Referring to  FIGS. 2, 7  and  8 , the knob assembly is shown in greater detail. The knob  9  is mounted to the spool  13  by a roll pin  90 . The handle assembly body  14  has a step  93  that extends for more than 180 degrees. The roll pin  90  is restrained by the step  93  and the head of a mushroom shaped pin  91  mounted in the handle assembly body  14 . This prevents the spool  13  from rotating by itself. To turn the knob  9 , the operator of the device must depress the trigger  10  all the way; in which event the roll pin  90  will be positioned to clear the head of the mushroom pin  91  upon rotation of the knob  9 . The knob can then be rotated 180 degrees from the “open center” position shown in  FIG. 7 , to the “closed center” position.  
         [0056]     To provide the operator with an indication of the operating condition of the device, I have provided indicia in the surface of the parts, as follows. An arrow  92  is provided in the surface of the handle assembly body  14 . An “O” indicating “open center” and a “C” indicating “closed center” are provided in the outer surface of the knob  9 ; for visual registration with the arrow  92  to indicate the condition of operation.  
         [0057]     The knob is knurled around the circumference to aid gripping it while turning it.  
         [0058]     In  FIG. 6 , the OC/CC knob  9  has been rotated to the closed-center position thereby rotating the spool. The spool obstructs passageway  61  and the oil is prevented from flowing through the check spool assembly means. The closed center condition is not used as frequently as the open center condition; but existing equipment may still require this mode of operation. In the closed center condition the check valve assembly means does not function as described above. The OC/CC knob mounted on the spool on this type of tool and being capable of changing the condition of operation without additional tools, is a feature totally unique in the industry.