Patent Publication Number: US-2010119393-A1

Title: Hydraulic pump assembly

Description:
FIELD 
     The present patent application is directed to pump assemblies and, more particularly, to hydraulic pump assemblies configured to supply a pressurized fluid line to various auxiliary applications. 
     BACKGROUND 
     Anti-lock braking systems typically include wheel speed sensors, an electronic control unit and a hydraulic control unit. The electronic control unit is integrated with the hydraulic control unit to form a hydraulic modulator or electro-hydraulic control unit. The hydraulic control unit may include a motor for pumping hydraulic fluid through various channels, accumulators for storing accumulated hydraulic fluid and valves having internal components for directing hydraulic fluid to the brakes. The electronic control unit may include a processor for receiving signals from the speed sensors and solenoid coils corresponding to each valve stem for actuating the valves according to command signals generated by the processor. The electronic control unit may be integrated with the hydraulic control unit such that the coils contact the valve stems, thereby forming the electro-hydraulic control unit. 
     Advances in electro-hydraulic control unit technology and, in particular, advances in the manufacture of electro-hydraulic control units, including the machining of the associated hydraulic control units, have resulted in efficiencies and economies of scale that led to mass production of electro-hydraulic control unit. As a result, anti-lock braking systems have become standard features of modern automobiles. 
     Elsewhere in the art, hydraulic pumps such as gear pumps and vane pumps are used to supply hydraulic fluid to various auxiliary applications, such as positioning applications (e.g., hydraulic door operators, conveyor belt tensioners and medical chairs and beds), recreational vehicle applications (e.g., leveling, slideouts and tent trailers), clamping applications (e.g., tool fixtures and jigs, hydraulic brakes, crimping tools, arbor presses and truck restraints), cycling applications (e.g., garbage compactors, valve operators, press controls, packing equipment and indexing tables), and lifting applications (e.g., handicap lifts, scissor lift tables and pellet movers). 
     It has been discovered that electro-hydraulic control unit technology may be used to supply a highly pressurized fluid line to various auxiliary applications, thereby providing a low-cost alternative to traditional hydraulic pumps for auxiliary applications. 
     SUMMARY 
     In one aspect, the disclosed hydraulic pump assembly may include a fluid reservoir, a body defining a fluid inlet and a fluid outlet, the fluid inlet being in fluid communication with the fluid reservoir, and a radially opposed piston pump assembly at least partially housed within the body and including a first piston pump mechanism and a second piston pump mechanism, the first piston pump mechanism being in fluid communication with the fluid inlet and having a first pump outlet, the second piston pump mechanism being in fluid communication with the fluid inlet and having a second pump outlet, wherein the first pump outlet and the second pump outlet are both in fluid communication with the fluid outlet. 
     In another aspect, the disclosed hydraulic pump assembly may include a fluid reservoir, a body defining a fluid inlet and a fluid outlet, the fluid inlet being in fluid communication with the fluid reservoir, a radially opposed piston pump assembly at least partially housed within the body and including a first piston pump mechanism, a second piston pump mechanism and an electric motor, the electric motor including an eccentric that engages the first and second piston pump mechanisms, the first piston pump mechanism being in fluid communication with the fluid inlet and having a first pump outlet, the second piston pump mechanism being in fluid communication with the fluid inlet and having a second pump outlet, wherein the first pump outlet and the second pump outlet are both in fluid communication with the fluid outlet, a first pump inlet check valve positioned in a first inlet fluid path within the body between the fluid reservoir and the first piston pump mechanism, a second pump inlet check valve positioned in a second inlet fluid path within the body between the fluid reservoir and the second piston pump mechanism, a first pump outlet check valve positioned in a first outlet fluid path within the body between the first piston pump mechanism and the first pump outlet, a second pump outlet check valve positioned in a second outlet fluid path within the body between the second piston pump mechanism and the second pump outlet, and a pressure relief valve in fluid communication with the fluid outlet. 
     Other aspects of the disclosed hydraulic pump assembly will become apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of one aspect of the disclosed hydraulic pump assembly connected to an auxiliary application; 
         FIG. 2  is a side elevational view of the hydraulic pump assembly of  FIG. 1 ; 
         FIG. 3  is a front elevational view, shown in section, of the hydraulic pump assembly of  FIG. 2 ; 
         FIG. 4  is a schematic illustration of a second aspect of the disclosed hydraulic pump assembly; 
         FIG. 5  is a front elevational view, shown in section, of the hydraulic pump assembly of  FIG. 4 ; 
         FIG. 6  is a schematic illustration of a third aspect of the disclosed hydraulic pump assembly; and 
         FIG. 7  is a front elevational view, shown in section, of the hydraulic pump assembly of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , one aspect of the disclosed hydraulic pump assembly, generally designated  6 , may include a radially opposed piston pump assembly  8 , a pressure relief valve  10 , and a fluid reservoir  12 . The radially opposed piston pump assembly  8  may include a first piston pump mechanism  7  and a second piston pump mechanism  9 , wherein the outputs of the first and second piston pump mechanisms  7 ,  9  may be combined to provide a single hydraulic fluid outlet  11 . The fluid outlet  11  of the radially opposed piston pump assembly  8  may be in fluid communication with an auxiliary application  18  by way of a pressurized fluid line  20 . The pressurized fluid line  20  may supply high pressure hydraulic fluid to the auxiliary application  18  and a return fluid line  22  may return hydraulic fluid from the auxiliary application  18  to the fluid reservoir  12  at atmospheric pressure. 
     In particular, as shown in  FIG. 2 , the hydraulic pump assembly  6  may include the fluid reservoir  12 , a hydraulic control unit body  14 , and a pump motor  16 . The hydraulic control unit body  14  may house the radially opposed piston pump assembly  8  and the pressure relief valve  10 , and, in response to rotational power supplied by the pump motor  16 , may operate to draw hydraulic fluid from the fluid reservoir  12 , pressurize the hydraulic fluid, communicate the hydraulic fluid to the auxiliary application  18  by way of fluid line  20 , and then return the hydraulic fluid to the fluid reservoir  12  by way of fluid line  22 . 
     The fluid reservoir  12  may be any vessel capable of storing a hydraulic fluid. For example, as shown in  FIGS. 2 and 3 , the fluid reservoir  12  may include a bottle  24  (e.g., a plastic bottle) and a cap  26  for securing hydraulic fluid within the bottle  24 . In one aspect, the fluid reservoir  12  may be connected to the body  14  to form an integral reservoir/body/motor assembly. In an alternative aspect, the fluid reservoir  12  may be physically separated from the body  14 , but in fluid communication with the body  14  by way of external fluid lines (not shown). 
     The pump motor  16  may be any appropriate motor having a motor shaft  28  ( FIG. 3 ) with an eccentric  30  ( FIG. 3 ) extending therefrom. In one example, the pump motor  16  may be a 12-volt electric motor with an eccentric  30  of about 0.85 mm to about 1.20 mm. In another example, the pump motor  16  may be a 24-volt motor. In another example, the pump motor  16  may be 10-volt motor. However, those skilled in the art will appreciate that the size of the pump motor  16 , the shaft  28  and the eccentric  30  will be dictated by design considerations. 
     As shown in  FIG. 2 , the pump motor  16  may be connected to the body  14  such that, as shown in  FIG. 3 , the motor shaft  28  and associated eccentric  30  extend into the shaft chamber  38  (discussed below) defined in the body  14  for engagement with the first and second pistons  66 ,  76  (discussed below). Therefore, rotational power from the pump motor  16  may be translated into flow and pressurization of hydraulic fluid within the body  14 . 
     Referring to  FIG. 3 , the body  14  may be a block of rigid material, such as aluminum, and may define a first fluid inlet bore  30 , a second fluid inlet bore  32 , a first piston bore  34 , a second piston bore  36 , a shaft chamber  38 , a first fluid outlet bore  40 , a second fluid outlet bore  42 , a connecting bore  44 , a pressure relief bore  46  and a fluid return bore  48 . The bores  30 ,  32 ,  34 ,  36 ,  40 ,  42 ,  44 ,  46 ,  48  and chamber  38  may be machined into the body  14  using any available technique (e.g., drilling). Plugs (discussed in greater detail below), such as ball plugs, may be inserted into the bores to seal the bores as appropriate. 
     The first fluid inlet bore  30  may be in fluid communication with the fluid reservoir  12  at a first end thereof and the first piston bore  34  at a second end thereof, and may define a valve seat  50  therein. A spring-loaded ball  52  may be received in the first fluid inlet bore  30  and may be biased into engagement with the valve seat  50 , thereby defining a first pump inlet check valve  54  between the first fluid inlet bore  30  and the first piston bore  34 . The first pump inlet check valve  54  may allow hydraulic fluid to flow from the fluid reservoir  12  to the first piston pump mechanism  7 , but not in the reverse direction. 
     The second fluid inlet bore  32  may be in fluid communication with the fluid reservoir  12  at a first end thereof and the second piston bore  36  at a second end thereof, and may define a valve seat  56  therein. A spring-loaded ball  58  may be received in the second fluid inlet bore  32  and may be biased into engagement with the valve seat  56 , thereby defining a second pump inlet check valve  60  between the second fluid inlet bore  32  and the second piston bore  36 . The second pump inlet check valve  60  may allow hydraulic fluid to flow from the fluid reservoir  12  to the second piston pump mechanism  9 , but not in the reverse direction. 
     The first piston bore  34  may include a plug  62  sealing a first end thereof and may connect with the shaft chamber  38  at a second end thereof. The first piston bore  34  may fluidly couple the first fluid inlet bore  30  with the first fluid outlet bore  40  (i.e., the outlet of the first piston pump mechanism  7 ) and may include a first pump outlet check valve  64  positioned between the first fluid inlet bore  30  and the first fluid outlet bore  40 . The first pump outlet check valve  64  may allow hydraulic fluid to flow from the first piston bore  34  to the first fluid outlet bore  40 , but not in the reverse direction. 
     A first piston  66  may be closely and sideably received in the first piston bore  34 . A seal  68  may create a fluid-tight seal across the first piston  66  such that hydraulic fluid does not pass across the first piston  66  from the first piston bore  34  and into the shaft chamber  38 . A biasing element  70 , such as a coil spring, may bias the first piston  66  out of the first piston bore  34  and in the direction of the shaft chamber  38  for engagement with the eccentric  30  of the shaft  28  of the pump motor  16 . 
     The second piston bore  36  may include a plug  72  sealing a first end thereof and may connect with the shaft chamber  38  at a second end thereof. The second piston bore  36  may fluidly couple the second fluid inlet bore  32  with the second fluid outlet bore  42  (i.e., the outlet of the second piston pump mechanism  9 ) and may include a second pump outlet check valve  74  positioned between the second fluid inlet bore  32  and the second fluid outlet bore  42 . The second pump outlet check valve  74  may allow hydraulic fluid to flow from the second piston bore  36  to the second fluid outlet bore  42 , but not in the reverse direction. 
     A second piston  76  may be closely and sideably received in the second piston bore  36 . A seal  78  may create a fluid-tight seal across the second piston  76  such that hydraulic fluid does not pass across the second piston  76  from the second piston bore  36  and into the shaft chamber  38 . A biasing element  80 , such as a coil spring, may bias the second piston  76  out of the second piston bore  36  and in the direction of the shaft chamber  38  for engagement with the eccentric  30  of the shaft  28  of the pump motor  16  ( FIG. 2 ). 
     As the pump motor  16  rotates the shaft  28  and associated eccentric  30 , the eccentric  30  alternately acts on the first and second pistons  66 ,  76  such that the pistons  66 ,  76  are urged into the associated first and second piston bores  34 ,  36 . Then, when the eccentric  30  passes, the biasing elements  70 ,  80  urge the associated pistons  66 ,  76  out of the associated piston bores  66 ,  76 . 
     Accordingly, due to the reciprocating action of the pistons  66 ,  76  caused by the pump motor  16  and the biasing elements  70 ,  80 , hydraulic fluid is drawn from the fluid reservoir  12 , through the first and second pump inlet check valves  54 ,  60 , and into the first and second piston bores  34 ,  36  when the pistons  66 ,  76  are urged out of the associated piston bores  34 ,  36  by the biasing elements  70 ,  80 . Then, when the pistons  66 ,  76  are urged into the associated piston bores  34 ,  36  by the eccentric  30 , the hydraulic fluid in the piston bores  34 ,  36  is urged through the first and second pump outlet check valves  64 ,  74  and into the first and second fluid outlet bores  40 ,  42 , thereby operating as the radially opposed piston pump assembly  8 . 
     The first fluid outlet bore  40  may include a first end  82  and a second end  84 . The first end  82  of the first fluid outlet bore  40  may be connected to the first piston bore  34  and a first end  86  of the connecting bore  44 . The second end  84  of the first fluid outlet bore may include a plug  88 , such as a ball plug, received therein to form an external seal. 
     The second fluid outlet bore  42  may include a first end  90  and a second end  92 . The first end  90  of the second fluid outlet bore  42  may be connected to the second piston bore  36  and a second end  94  of the connecting bore  44 . (A plug  96 , such as a ball plug, may be used to seal the external portion of the second end  94  of the connecting bore  44 .) The second end  92  of the second fluid outlet bore  42  may be connected to an outlet port  93 , which may be connected to the pressurized fluid line  20  for directing hydraulic fluid to the auxiliary application  18  ( FIG. 2 ). 
     Thus, the connecting bore  44  may combine the first and second fluid outlet bores  40 ,  42  (i.e., both outputs of the radially opposed piston pump assembly  8 ) into a single fluid outlet port  93 . 
     Still referring to  FIG. 3 , the pressure relief bore  46  may define a valve seat  98  therein and may include a first end  100  in fluid communication with the connecting bore  44  and a second end  102  having threads formed therein. A spring-loaded ball  104  or the like may be positioned in the pressure relief bore  46  to engage the valve seat  98  and form a pressure sensitive seal therebetween, thereby operating as the pressure relief valve  10 . A return bore  106  extending between the fluid reservoir  12  and the pressure relief bore  46  may fluidly couple the pressure relief bore  46  with the fluid reservoir  12 . The return bore  106  may be connected to the pressure relief bore  46  at a point between the valve seat  98  and the second end  102  of the pressure relief bore  46 . 
     A pressure relief control screw  108  may engage the threads at the second end  102  of the pressure relief bore  46  and a seal  110  may provide a fluid tight seal between the pressure relief bore  46  and the pressure relief control screw  108 . Rotation of the pressure relief control screw  108  about the threads may compress the spring-loaded ball  104 , thereby urging the spring-loaded ball  104  against the valve seat  98  with greater force, thereby increasing the amount of fluid pressure that may be resisted by the spring-loaded ball  104  before the spring-loaded ball  104  is displaced from the valve seat  98  to release hydraulic fluid to the fluid reservoir  12  through the return bore  106 . 
     The fluid return bore  48  may include a first end  112  and a second end  114 . The first end  112  of the fluid return bore  48  may be in fluid communication with the fluid reservoir  12 . The second end  114  of the fluid return bore  48  may be connected to a return port  116 . The return port  116  may be connected to the return fluid line  22  for directing return fluid to the fluid reservoir  12 . 
     At this point, those skilled in the art will appreciate that the body  14  of the hydraulic pump assembly  6  may be formed by machining a solid block of material (e.g., aluminum) to form a plurality of bores having the desired configuration and geometry, and inserting the necessary plugs and components (e.g., pistons, check valves and biasing elements) into the bores to form the radially opposed piston pump assembly  8  that delivers a single, high pressure fluid outlet and the pressure relief valve  10  that controls excess fluid pressure within the hydraulic pump assembly  6 . 
     Accordingly, those skilled in the art will appreciate that the disclosed hydraulic pump assembly  6  may provide a low-cost, high-volume radial two piston pump and motor assembly with an integral pressure relief valve, and, optionally, an integral plastic fluid reservoir. 
     Referring to  FIGS. 4 and 5 , a second aspect of the disclosed hydraulic pump assembly, generally designated  200 , may include a hydraulic control unit body  201  ( FIG. 5 ), a pump motor  203  ( FIG. 4 ), a pressure relief valve  204 , a fluid reservoir  206  and a manual control valve  208 . The hydraulic control unit body  201  and the pump motor  203  may combine to form a radially opposed piston pump assembly  202 . The radially opposed piston pump assembly  202 , the pressure relief valve  204  and the fluid reservoir  206  may be configured in the manner described above in connection with the hydraulic pump assembly  6 . However, those skilled in the art will appreciate that the radially opposed piston pump assembly  202 , the pressure relief valve  204  and the fluid reservoir  206  may be configured in various ways. 
     The manual control valve  208  may be a three-position, two-way bi-direction spool valve having a moveable spool  213  received in a bore  209  defined in the body  201  of the assembly  200 . The manual control valve  208  may be in communication with the combined fluid output  211  of the radially opposed piston pump assembly  202  by way of a first fluid channel  210 , the fluid reservoir  206  by way of a second fluid channel  212 , a first bi-directional input/output port  214  and a second bi-directional input/output port  216 . Those skilled in the art will appreciate that the combined fluid output  211 , the first and second fluid channels  210 ,  212  and the first and second input/output ports  214 ,  216  may be formed as bores machined into the body  201  of the assembly  200 . 
     As shown in  FIG. 4 , the first and second input/output ports  214 ,  216  may be in fluid communication with an auxiliary application  218  by way of first and second fluid lines  220 ,  222 . The auxiliary application  218  is shown in  FIG. 4  as a hydraulic cylinder; however, those skilled in the art will appreciate that the auxiliary application  218  may be any auxiliary device that can be manipulated by the application of pressurized hydraulic fluid. 
     In the first (e.g., left) position (not shown), the spool  213  may be shifted in the direction of arrow C ( FIG. 5 ) such that the manual control valve  208  may connect the first input/output port  214  with the first fluid channel  210  (i.e., the pressurized fluid) by way of a first valve bore  230  and the second input/output port  216  with the second fluid channel  212  (i.e., the reservoir) by way of a second valve bore  232 . In the first position, the first input/output port  214  may be pressurized while the second input/output port  216  may be depressurized, thereby pressurizing the piston chamber  224  of the auxiliary application  218  and depressurizing the rod chamber  226  of the auxiliary application  218 . 
     In the second (e.g., middle) position (shown in  FIG. 4 ), the spool  213  may be centered in the bore  209  such that the first fluid channel  210  (i.e., the pressurized fluid) is in fluid communication with a third valve bore  234 , which is not in fluid communication with either the first input/output port  214  or the second input/output port  216 , and the second fluid channel  212  (i.e., the reservoir) is in fluid communication with a fourth valve bore  236 , which is not in fluid communication with either the first input/output port  214  or the second input/output port  216 . Therefore, in the second position, the manual control valve  208  locks hydraulic fluid in the first and second input/output ports  214 ,  216 , thereby locking the auxiliary application  218  in a fixed position. 
     In the third (e.g., right) position (not shown), the spool  213  may be shifted in the direction of arrow D ( FIG. 5 ) such that the manual control valve  208  may connect the first input/output port  214  with the second fluid channel  212  (i.e., the reservoir) by way of a fifth valve bore  238  and the second input/output port  216  with the first fluid channel  210  (i.e., the pressurized fluid) by way of a sixth valve bore  240 . In the third position, the first input/output port  214  may be depressurized while the second input/output port  216  may be pressurized, thereby depressurizing the piston chamber  224  of the auxiliary application  218  and pressurizing the rod chamber  226  of the auxiliary application  218 . 
     Accordingly, those skilled in the art will appreciate that the disclosed hydraulic pump assembly  200  may provide a low-cost, high-volume radial two piston pump and motor assembly with an integral pressure relief valve, an integral plastic fluid reservoir, and an integral three-position, bi-directional spool valve for manual pressure control. 
     Referring to  FIGS. 6 and 7 , a third aspect of the disclosed hydraulic pump assembly, generally designated  300 , may include a hydraulic control unit body  301 , a pump motor  303 , a pressure relief valve  304 , a fluid reservoir  306 , a first normally closed solenoid actuated poppet valve  308  (actuated by electric switch  314 ), and a second normally closed solenoid actuated poppet valve  310  (actuated by electric switch  316 ). The hydraulic control unit body  301  and the pump motor  303  may combine to form a radially opposed piston pump assembly  302  (actuated by electric switch  312 ), The radially opposed piston pump assembly  302 , the pressure relief valve  304  and the fluid reservoir  306  may be configured in the manner described above in connection with the hydraulic pump assembly  6 . However, those skilled in the art will appreciate that the radially opposed piston pump assembly  302 , the pressure relief valve  304  and the fluid reservoir  306  may be configured in various ways. 
     Furthermore, the hydraulic pump assembly  300  may include a first, constant high pressure outlet port  318  and a second, variable pressure outlet port  320 . The first outlet port  318  may be in fluid communication with the radially opposed piston pump assembly  302  by way of a first bore  322  and a rod chamber  324  of a hydraulic cylinder  326  by way of a first fluid line  328  ( FIG. 6 ). The second outlet port  320  may be in fluid communication with the radially opposed piston pump assembly  302  by way of a second bore  330 , the fluid reservoir  306  by way of a third bore  332 , and a rod chamber  334  of the hydraulic cylinder  326  by way of a second fluid line  336  ( FIG. 6 ). The second bore  330  may be interrupted by the first normally closed solenoid actuated poppet valve  308  and the third bore  332  may be interrupted by the second normally closed solenoid actuated poppet valve  310 . 
     In a first configuration of the disclosed hydraulic pump assembly  300 , the radially opposed piston pump assembly  302  may be actuated by the switch  312 , but the first and second solenoid actuated poppet valves  308 ,  310  may not actuated, thereby locking the hydraulic cylinder  326 . In a second configuration of the disclosed hydraulic pump assembly  300 , the radially opposed piston pump assembly  302  may be actuated by the switch  312 , the first solenoid actuated poppet valve  308  may be actuated by the switch  314 , and the second solenoid actuated poppet valve  310  may not be actuated, thereby pressurizing the piston chamber  334  and driving the piston  335  in the direction shown by arrow A. (Equal pressures in the piston and rod chambers  334 ,  324 , but the rod chamber  324  has less surface area due to the rod.) In a third configuration of the disclosed hydraulic pump assembly  300 , the radially opposed piston pump assembly  302  may be actuated by the switch  312 , the second solenoid actuated poppet valve  310  may be actuated by the switch  316 , and the first solenoid actuated poppet valve  308  may not be actuated, thereby pressurizing the rod chamber  324  and driving the piston  335  in the direction shown by arrow B. In a fourth configuration of the disclosed hydraulic pump assembly  300 , the radially opposed piston pump assembly  302  may be actuated by the switch  312 , the first solenoid actuated poppet valve  308  may be actuated by the switch  314 , and the second solenoid actuated poppet valve  310  may be actuated by the switch  316 , thereby freeing the hydraulic cylinder  326  and removing the load from the radially opposed piston pump assembly  302 . 
     Accordingly, those skilled in the art will appreciate that the disclosed hydraulic pump assembly  300  may provide a low-cost, high-volume radial two piston pump and motor assembly with an integral pressure relief valve, an integral plastic fluid reservoir, and integral solenoid actuated poppet valves allowing for remote operation and full pressure control using electric switches. 
     Although various aspects of the disclosed hydraulic pump assembly have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.