Abstract:
A fluid isolator includes a primary outlet port adapted-to be coupled to a hydraulic device; a bleed valve having a first and a second position; a first line in fluid communication with the primary outlet port and the bleed valve; a first and second one way valve located in the first line inhibiting the flow of fluid toward the primary outlet port; a primary gauge port adapted to be coupled with a pressure gauge; and a second line in fluid communication with the primary gauge port and a portion of the first line located between the first and the second one way valve; wherein the bleed valve is switchable between the first and second position to permit the flow of fluid from the primary outlet port to a region of lower fluid pressure.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a fluid isolator. In particular, the present invention relates to a hydraulic isolator for depressurising hydraulic circuits. However, it will be appreciated that the fluid isolator may be used with pneumatic circuits and other applications. 
       BACKGROUND OF THE INVENTION 
       [0002]    Hydraulic systems provide power transfer and movement in equipment used in various technology areas, such as machinery used in mining, construction and agriculture. 
         [0003]    It is necessary to de-pressurise a hydraulic line or circuit at certain times, for example when a hydraulic hose needs to be disconnected during maintenance or servicing. The de-pressurisation process is essential to reduce the risk of injury to personnel by high pressure fluid. However, despite workers being generally aware of the issues and prevailing risks, accidents still occur with hydraulic fluid. One problem that arises relates to the residual pressure in a hydraulic line which may still be dangerously high after an attempted de-pressurisation has been conducted. 
         [0004]    Secondly, technicians sometimes mistakenly assume that a line has low or no pressure, when in fact it is still under high pressure. 
         [0005]    Hydraulic couplings historically utilised male and female threaded fasteners. Accordingly, when a technician believed a hydraulic line to have been safely depressurised, by slowly unscrewing the thread, the hydraulic fluid would leak immediately after the seal was broken, indicating to the technician if the line still contained high pressure fluid. 
         [0006]    However, a recent trend in hydraulic equipment is that lines are increasingly being coupled together with snap lock type fittings. Whilst snap lock fittings are fast to connect and disconnect, they provide the disadvantage of being very dangerous if they are disconnected while the line pressure is still too high. Because the snap lock fitting is fast to disconnect, there are incidents of personnel being injured and killed by the hose whipping around, and either striking a person, or spraying the person with hydraulic fluid which may be at very high pressures, and temperatures. 
         [0007]    In the event of a fire occurring on or near a hydraulically operated machine, there is a risk of the fire burning through one or more hydraulic lines. This can cause several significant problems, such as the rapid de-pressurisation of the hydraulic circuit resulting in machinery such as booms or other raised or pressurised components falling quickly to the ground. In addition, most hydraulic fluids are mineral oil based, and hence flammable, which adds to the intensity and danger of such fires occurring around hydraulic machinery. 
       OBJECT OF THE INVENTION 
       [0008]    It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or at least to provide a useful alternative. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first aspect, the present invention provides a fluid isolator comprising:
       a primary outlet port adapted to be coupled to a hydraulic device;   a bleed valve having a first position and a second position;   a first line in fluid communication with the primary outlet port and the bleed valve;   a first one way valve located in the first line, the first one way valve inhibiting the flow of fluid toward the primary outlet port;   a second one way valve located in the first line, the second one way valve inhibiting the flow of fluid toward the primary outlet port;   a primary gauge port adapted to be coupled with a pressure gauge; and   a second line in fluid communication with the primary gauge port and a portion of the first line located between the first one way valve and the second one way valve;   wherein the bleed valve is switchable between the first position and the second position to permit the flow of fluid from the primary outlet port to a region of lower fluid pressure.       
 
         [0018]    The fluid isolator further preferably comprising one or more secondary outlet ports, each secondary outlet port being adapted to be coupled to an additional hydraulic device,
       a third line extending between each secondary outlet port and the first line between the second one way valve and the bleed valve;   a third one way valve located in the third line, the third one way valve inhibiting the flow of fluid toward the secondary outlet port;   a fourth one way valve located in the third line, the fourth one way valve inhibiting the flow of fluid toward the secondary outlet port;   an secondary gauge port adapted to be coupled with a pressure gauge; and   a fourth line in fluid communication with the secondary gauge port and a portion of the third line located between the third one way valve and the fourth one way valve.       
 
         [0024]    A first test port is preferably located in the first line between the second one way valve and the bleed valve. 
         [0025]    A second test port is preferably located in the first line between the second one way valve and the bleed valve. 
         [0026]    The primary and secondary gauge ports are preferably double check valves. 
         [0027]    The bleed valve is preferably a direction control valve. In particular, the bleed valve is preferably a four port two position direction control valve. 
         [0028]    The bleed valve is preferably manually operable. Alternatively the bleed valve may include a solenoid and is electrically operable. 
         [0029]    The fluid isolator preferably comprises a manual control to selectively provide fluid communication with the primary gauge port and the secondary gauge port. 
         [0030]    The manual control is preferably a button, knob or lever. 
         [0031]    In a second aspect, the present invention provides a hydraulic system comprising:
       a fluid isolator as described above;   a fluid reservoir in fluid communication with the bleed valve;   a pump in fluid communication with the fluid reservoir;   a control valve in fluid communication with the pump;   an accumulator in fluid communication with the control valve and one of the primary or secondary outlet ports of the fluid isolator;   a hydraulic device in fluid communication with the control valve; and   a line extending between one of said primary or secondary outlet ports of the fluid isolator and a line extending between the control valve and the hydraulic device.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]    A preferred embodiment of the invention will now be described by way of specific example with reference to the accompanying drawings, in which: 
           [0040]      FIG. 1  depicts a hydraulic circuit according to the invention; 
           [0041]      FIG. 2  is a front view of a hydraulic isolator according to an embodiment of the invention; 
           [0042]      FIG. 3  is a top view of the hydraulic isolator of  FIG. 2 ; 
           [0043]      FIG. 4  is a rear view of the hydraulic isolator of  FIG. 2 ; and 
           [0044]      FIG. 5  is a schematic view of a hydraulic system including the isolator of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0045]    A fluid isolator  10  for use in hydraulic or pneumatic systems is disclosed in  FIG. 1 . The isolator  10  is housed in a manifold  12  which is depicted in  FIGS. 2 to 4 . The manifold  12  is configured to provide the required number of hydraulic outputs for a given hydraulic application. The number of outputs is typically between  4  and  20 , although other amounts are possible. 
         [0046]    The isolator  10  includes a bleed valve  14  in the form of a direction control valve  14 . The valve  14  is typically a four port two position valve  14 , although other suitable valves may be utilised. The direction control valve  14  may be controlled manually or by an electrically operated solenoid. As depicted in  FIG. 1 , a hydraulic line  16  is in fluid communication with a hydraulic tank or reservoir  15 . The line  16  branches into two hydraulic lines  18 ,  20 . In the first and second positions of the vale  14 , there is no flow of hydraulic fluid across the direction control valve  14  between lines  18  and  20 . In some embodiments, the line  20  may not be included. 
         [0047]    Another hydraulic line  24  is in fluid communication with the direction control valve  14 . This line  24  terminates at the housing of the manifold  12  with a port which is labelled “B” on the manifold  12 . A further hydraulic line  26  is also in fluid communication with the direction control valve  14 . Line  24  may be blocked at “B” to prevent the flow if fluid when the isolator is in the valve  14  position depicted in  FIG. 1 . 
         [0048]    In the direction control valve  14  position depicted in  FIG. 1 , there is fluid flow across the valve  14  between lines  24  and  26 , however as described above, line  24  does not provide a fluid flow path. 
         [0049]    In the alternative switch position (not shown) there is no fluid flow across the valve  14  between lines  24  and  26 . In contrast, in the alternative switch position (corresponding to a hydraulic fluid depressurisation or dump) line  26  is connected to the tank  15  through lines  18  and  16 . 
         [0050]    The isolator  10  includes at least one outlet port  30 . However, in the embodiment shown in  FIG. 1 , there is an array of fifteen outlet ports  30 . Each outlet port  30  corresponds to a given hydraulic motor, cylinder or other such hydraulically operated component on hydraulic machine. For example, on an excavator, output  30   a  may be used to energise a first side of a first double acting cylinder to tilt the bucket. Output  30   b  in contrast may be used to energise the opposing side of the first double acting cylinder. In contrast output  30   c  may be used to extend a boom of the excavator, to raise the bucket. As such, the isolator  10  is provided with a sufficient number of outlet ports  30  to correspond with the number of hydraulic devices on a given hydraulic machine. 
         [0051]    Each outlet port  30  is connected to a respective hydraulic line  32 . A first one way check valve  40  is provided in each line  32 . The first one way check valves  40  permits the hydraulic fluid to flow from the outlet port  30  into an isolated oil gallery  50 . In addition, the first one way check valve  40  prevents the hydraulic fluid from back flowing from the isolated oil gallery  50  to the outlet port  30 . 
         [0052]    Each isolated oil gallery  50  includes a first line  52  extending between the first one way check valve  40  and a second one way check valve  60 . The isolated oil gallery  50  also includes another line  54  which branches off the first line  52 , and is in fluid communication with a gauge port  70 . As such, there is a gauge port  70  corresponding to each outlet port  30 . The gauge ports  70  are depicted in the  FIGS. 2 to 4  by G 1  to G 13  (in this embodiment there are  13  inlet ports  30  and  13  gauge ports  70 ). 
         [0053]    In the embodiment of  FIGS. 2 to 4 , a manual switch, lever or knob  72  is connected to each gauge port  70 . By manually operating the switch  72 , the gauge port  70  is opened or closed. In use a technician can connect a hydraulic pressure gauge (not shown) to a desired gauge port  70  and then operate the corresponding manual switch  72  to permit fluid flow across the gauge port  70 , to obtain a pressure measurement for a given outlet port  30 . 
         [0054]    Alternatively in the embodiment depicted in  FIG. 1 , the combination of the gauge port  70  and manual switch  72  is replaced with a double check valve  76 , such as a quick connect ball valve coupler or other such valve. This negates the need for the manual operation of any switch, and removes the risk of a technician removing the pressure gauge while the gauge port  70  is open. 
         [0055]    Because each isolated oil gallery  50  is in fluid communication with the corresponding supply port  30 , an accurate indication of the pressure with the corresponding hydraulic device can be obtained. 
         [0056]    Each second one way check valve  60  provides fluid communication with a common high pressure oil gallery  28 . The high pressure oil gallery  28  is integral with or in direct fluid communication with line  26 . Each of the second one way check valves  60  for each of the inlet ports  30  is connected to the common high pressure oil gallery  28 . As such, the common high pressure oil gallery  28  will be under pressure if any one of the outlet ports  30  are pressurised. 
         [0057]    A common first test port  80  is connected to the line  26  and hence the common high pressure oil gallery  28 . The common test port  80  can be used to indicate to a technician if there is pressure in any one or more of the outlet ports  30 . A second test port  82  may also be provided. The second test port  82  may be connected to a gauge mounted elsewhere in the system, such as in the driver&#39;s cabin or control room. This provides a constant indication that at least a portion of the system is under pressure, which may be useful. This may be in the form of a gauge, digital display, light or other such indicator. 
         [0058]    In the event of a rapid depressurisation, i.e. if there is a fire, or alternatively during scheduled maintenance or repairs, the direction control valve  14  is switched from the position depicted in  FIG. 1  to the second position, in which line  26  comes into fluid communication with line  18 . The pressure in lines  18 ,  16  and the tank  15  is generally much lower than the pressure in the common high pressure oil gallery  28 , so the hydraulic fluid rapidly bleeds back to the tank  15 , and the isolator  10  is quickly depressurised. 
         [0059]    The direction control valve  14  may have a manual dump handle  88  to bleed the isolator  10 . The direction control valve  14  is generally a NC (normally closed) valve which opens when the handle  88  is depressed. The handle  88  may also have a lockout feature which allows the handle  88  to be locked in the open (bleed) position for maintenance on the hydraulic system and to prevent pressure build up in the hydraulic system. 
         [0060]    The direction control valve  14  may alternatively or also be operable by an electrically controlled solenoid  90 . The solenoid  90  may be wired into the fire detection and prevention system of a hydraulic machine, such that the direction control valve  14  is switched to the open, fluid bleed position in the event of a fire. The solenoid  90  may be controlled by the machines OEM or aftermarket fire system, or alternatively via the machines E-Stop circuit. 
         [0061]      FIG. 5  depicts the hydraulic isolator  10  installed in a hydraulic system  100 . The isolator  10  outlet ports  30  are in direct fluid communication with each of the hydraulic lines  103  connected to a hydraulic device  104  such as a cylinder of the system  100 . One or more of the outlet ports  30  of the isolator  10  are also in fluid communication with the accumulator  102 . As shown, each hydraulic device  104  is controlled by a control valve  108 , which receives hydraulic fluid from a pump  110 , which in turn is supplied by the tank  15 . By opening the direction control valve  14 , the hydraulic pressure in the pressurised side of the hydraulic system (between the pump  110  outlet  111  and the isolator  10 ) drops dramatically, until the pressure equalises within the system  100 . Advantageously, even if the pump  110  and control valve  108  remain activated, the pressure in the hydraulic device  104  will not increase while the direction control bleed valve  14  remains open. 
         [0062]    Advantageously, the isolator  10  enables a technician to test for stored pressure both and after the release of pressure either on a circuit by circuit basis, or from one central point. 
         [0063]    Advantageously, the isolator  10  can be easily retrofitted to existing hydraulic machinery. 
         [0064]    Advantageously, the circuits cannot be cross contaminated, and there is no possibility of a circuit being pressurised due to check valve design. 
         [0065]    Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.