US20090104047A1 - Pump having multiple minimum flow mechanical stops - Google Patents
Pump having multiple minimum flow mechanical stops Download PDFInfo
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- US20090104047A1 US20090104047A1 US12/285,819 US28581908A US2009104047A1 US 20090104047 A1 US20090104047 A1 US 20090104047A1 US 28581908 A US28581908 A US 28581908A US 2009104047 A1 US2009104047 A1 US 2009104047A1
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- Prior art keywords
- pump
- swashplate
- mechanical stops
- housing
- minimum
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/26—Control
- F04B1/30—Control of machines or pumps with rotary cylinder blocks
- F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
- F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
Definitions
- the present disclosure relates generally to a pump and, more particularly, to a pump having multiple minimum flow mechanical stops.
- Hydraulic tool systems typically employ multiple actuators provided with high pressure fluid from a common pump.
- these systems generally include a pump having variable displacement. Based on individual and/or combined flow and pressure requirements, the pump changes a fluid displacement amount to meet demands. When demand is low, the displacement is reduced to conserve energy.
- Typical variable displacement pumps used in hydraulic tool systems are known as swashplate or piston type pumps.
- This type of pump includes a plurality of pistons held against the driving surface of a tiltable swashplate.
- a joint such as a ball and socket joint is disposed between each piston and the swashplate to allow for relative movement between the swashplate and the pistons.
- Each piston is slidably disposed to reciprocate within an associated barrel as the pistons rotate relative to the tilted surface of the swashplate.
- low pressure fluid is drawn into that barrel.
- the piston pushes the fluid from the barrel at an elevated pressure.
- the tilt angle of the swashplate is directly related to an amount of fluid pushed from each barrel during a single relative rotation between the pistons and the swashplate. And, based on a restriction of the pump and/or a fluid circuit connected to the pump, the amount of fluid pushed from the barrel during each rotation is directly related to the flow rate and pressure of fluid exiting the pump.
- a higher tilt angle equates to a greater flow rate and pressure, while a lower tilt angle results in a lower flow rate and pressure.
- a higher tilt angle requires more power from a driving source to produce the higher flow rates and pressures than does a lower tilt angle. As such, when the demand for fluid is low, the swashplate angle is typically reduced to lower the power consumption of the pump.
- lowering the swashplate angle too low may result in a sluggish hydraulic tool system. That is, when the angle of the swashplate must ramp up through a relatively large angle to produce a demanded flow rate and/or pressure, the time required for that movement may also be large. As such, the pump may be slow to produce a high flow rate and/or pressure when starting at a very low tilt angle. And, in some cases, movement of the hydraulic tool system may not be possible until the pressure of the fluid exiting the pump exceeds a predetermined threshold level. Thus, even after a demand for fluid is transmitted to the pump, the actuators may not immediately be capable of movement.
- U.S. Pat. No. 5,567,123 (the '123 patent) issued to Childress et al. on Oct. 22, 1996 describes a swashplate type pump having a minimum allowable tilt angle.
- the swashplate angle is inhibited from being reduced below the minimum allowable tilt angle by way of a mechanical stop. That is, the mechanical stop engages the swashplate at the minimum angle to inhibit further reduction.
- some flow from the pump may always be available for use by associated hydraulic actuators and, because the swashplate is always tilted to some degree, the time required to meet high fluid demands may be reduced.
- the pump of the '123 patent may effectively improve system responsiveness, the improvement may be insufficient or undesired in some situations. That is, based on the application at hand, the minimum swashplate angle may be too low or too high, resulting in low responsiveness or low efficiency. In addition, different machine operators may have preferences regarding the minimum pump flow that are not fully satisfied with a single fixed tilt angle limit.
- the disclosed pump is directed to overcoming one or more of the problems set forth above.
- the present disclosure is directed to a pump.
- the pump may include a housing, and at least one pumping mechanism disposed within the housing.
- the at least one pumping mechanism may have a variable displacement.
- the pump may also include a plurality of available mechanical stops. Each of the plurality of available mechanical stops may be connectable to the housing and configured to limit a minimum displacement of the at least one pumping mechanism to a different amount.
- the present disclosure is directed to a method of pressurizing fluid.
- the method may include rotating a shaft to force fluid from a pumping chamber.
- the method may further include replacing a first component with a second component having a different effective length to change a minimum amount of fluid forced from the pumping chamber during a rotation of the shaft.
- the present disclosure is directed to a pump kit.
- the pump kit may include a first mechanical stop connectable to a variable displacement swashplate type pump.
- the first mechanical stop may be configured to limit a minimum displacement tilt angle of the variable displacement swashplate type pump to a first angle greater than zero relative to a perpendicular of a driveshaft of the variable displacement swashplate type pump.
- the pump kit may also include at least a second mechanical stop connectable to the variable displacement swashplate type pump.
- the at least a second mechanical stop may be configured to limit a minimum displacement tilt angle of the variable displacement swashplate type pump to a second angle greater than zero relative to the perpendicular of the driveshaft of the variable displacement swashplate type pump.
- the pump kit may further include instructions for changing an effective displacement of the variable displacement swashplate type pump.
- FIG. 1 is a diagrammatic illustration of an exemplary disclosed pump
- FIG. 2 is diagrammatic illustration of an exemplary pumping portion of the pump of FIG. 1 ;
- FIG. 3 is a cross-sectional illustration of an exemplary mechanical stop for use with the pumping portion of FIG. 2 ;
- FIG. 4 is a cross-sectional illustration of another exemplary mechanical stop for use with the pumping portion of FIG. 2 .
- FIG. 1 illustrates a pump 10 .
- pump 10 may be driven by an external source of power (not shown), such as a combustion engine, via a driveshaft 12 .
- driveshaft 12 may extend from one end of a pump housing 14 for engagement with the engine.
- housing 14 may enclose a body 16 defining a plurality of barrels 18 (only one shown).
- Pump 10 may also include a plurality of plungers 20 , one plunger 20 slidingly disposed within each barrel 18 .
- Each barrel 18 and each associated plunger 20 may, together, at least partially define a pumping chamber 22 .
- any number of pumping chambers 22 may be included within body 16 and symmetrically and radially disposed about a central axis 24 .
- central axis 24 may be coaxial with driveshaft 12 . However, it is contemplated that central axis 24 may be at an angle relative to driveshaft 12 such as in a bent-axis type pump.
- Body 16 may be connected to rotate with driveshaft 12 . That is, as driveshaft 12 is rotated by the engine, body 16 and plungers 20 located within barrels 18 of body 16 may all rotate together about central axis 24 .
- Pump 10 may be a swashplate type pump.
- pump 10 may include a stationary swashplate 26 having a driving surface 28 and a tilt frame 30 .
- Driving surface 28 may be operatively engaged with plungers 20 by way of a joint 32 such as a ball and socket joint. That is, each plunger 20 may have a generally spherical end 34 , which is biased into engagement with a cup-like socket 36 .
- Sockets 36 may be configured to slide along driving surface 28 , which may be fixedly connected to tilt frame 30 .
- Swashplate 26 may be tilted to vary a displacement of plungers 20 within barrels 18 .
- tilt frame 30 may be situated within a bearing member 38 and pivotal about a tilt axis 40 .
- tilt axis 40 may pass through and be substantially perpendicular to central axis 24 .
- the plungers 20 located on one half of driving surface 28 (relative to tilt axis 40 ) may retract into their associated barrels 18 , while the plungers 20 located on an opposing half of driving surface 28 may be extended out of their associated barrels 18 by the same amount.
- plungers 20 rotate about central axis 24 , plungers 20 may annularly move from the retracted side of driving surface 28 to the extended side, and repeat this cycle as driveshaft 12 rotates.
- plungers 20 retract out of barrels 18 , low pressure fluid may be drawn into barrels 18 . Conversely, as plungers 20 extend into barrels 18 , the fluid may be forced from barrels 18 at an elevated pressure.
- An amount of movement between the retracted position and the extended position may relate to a flow rate of fluid displaced by plungers 20 during a single rotation of driveshaft 12 .
- the tilt angle (angle relative to a perpendicular of central axis 24 that results in positive displacement of plungers 20 ) of driving surface 28 may relate to the movement between the retracted position and the extended position.
- One or more pressure relief valves located within pump 10 or within a hydraulic circuit (not shown) supplied with fluid from pump 10 , may affect the pressure of the fluid forced from barrels 18 .
- Swashplate 26 may be tilted about tilt axis 40 by way of an actuator 42 .
- Actuator 42 may be disposed within a bore (not shown) of housing 14 and connected to tilt frame 30 by way of an arm 44 protruding from one side of tilt frame 30 .
- an actuator bracket 46 may be pivotally connected to protruding arm 44 , and fixedly connected to actuator 42 .
- Actuator 42 may translate linearly in the general direction of central axis 24 to pivot tilt frame 30 about tilt axis 40 .
- actuator 42 may move in a first direction away from an input end of driveshaft 12 to increase a tilt angle of driving surface 28 .
- actuator 42 may move in a second direction toward the input end of driveshaft 12 to decrease a tilt angle of driving surface 28 .
- Actuator 42 may be powered in any conventional manner, including, among other ways, hydraulically, electrically, pneumatically, and mechanically.
- pump 10 may include a mechanical stop 48 disposed generally coaxially with actuator 42 in the bore of housing 14 , and connected to housing 14 by way of one or more fasteners 50 .
- mechanical stop 48 may inhibit the motion of actuator 42 in the second direction such that the resulting tilt angle of driving surface 28 ensures plungers 20 always extend into barrels 18 to displace fluid during the rotation of driveshaft 12 (i.e., mechanical stop 48 may always ensure positive displacement of pump 10 ).
- the minimum tilt angle of swashplate 26 may be directly related to the extension distance of mechanical stop 48 into the actuator bore of housing 14 . That is, a longer mechanical stop 48 may limit the tilt angle of swashplate 26 to a greater angle, as compared to a shorter mechanical stop 48 .
- FIG. 3 illustrates one embodiment of mechanical stop 48 .
- mechanical stop 48 resembles a plug having an extension length “L”.
- Extension length “L” may be considered the distance from an internal flange surface 51 to an end surface 52 that abuts actuator 42 .
- length “L” may be in the range of about 34-39 mm.
- a first embodiment of mechanical stop 48 may have a length “L” of about 34.6 mm.
- a second embodiment of mechanical stop 48 may have a length “L” of about 36.6 mm.
- a third embodiment of mechanical stop 48 may have a length “L” of about 38.6 mm.
- the minimum tilt angle limit of swashplate 26 may be related to a responsiveness of pump 10 . That is, a greater amount of time required for swashplate 26 to move from the minimum tilt angle to a desired tilt angle may result in a slow or sluggish pump. In contrast, a lower amount of time required for swashplate 26 to move from the minimum tilt angle to a desired tilt angle may result in a responsive pump. As movement of actuator 42 may be substantially constant, the time required for the movement of swashplate 26 may be directly related to the angular distance between the minimum tilt angle and the desired tilt angle. Thus, for a given desired tilt angle, a lower minimum tilt angle may require more movement time and, thus, result in a less responsive pump, as compared to a greater minimum tilt angle.
- the minimum tilt angle limit of swashplate 26 may also relate to an efficiency of pump 10 . That is, a greater minimum tilt angle of driving surface 28 may displace plungers 20 further into barrels 18 to pressurize a greater amount of fluid per revolution of driveshaft 12 during a standby condition, as compared to a lower minimum tilt angle. Thus, at the greater minimum tilt angle, the power source driving pump 10 may be loaded to a greater degree to pressurize a greater amount of unused fluid (the pressurized fluid may be substantially unused and drained to a low pressure tank during standby conditions). For this reason, a greater minimum tilt angle may result in a lower efficiency of pump 10 and the power source driving pump 10 .
- one of responsiveness and efficiency may be more important than the other. That is, in a first situation, responsiveness at the cost of efficiency may be desirable, while in a second situation, efficiency may be much more important than responsiveness.
- the mechanical stop 48 having the length “L” of 34.6 mm may be optimal.
- the mechanical stop 48 having the length “L” of 38.6 mm may be optimal.
- the length “L” may be selected for use based on an intended application of pump 10 and/or a machine incorporating pump 10 . Alternatively, the length “L” may be chosen based on an operator preference.
- a pump adjustment kit may be created having multiple mechanical stops 48 .
- This kit may include one mechanical stop 48 of each length “L”.
- the kit may include instructions for removing the existing mechanical stop 48 and inserting a replacement mechanical stop 48 having a different length.
- the kit may have a single part number, meaning that the kit can be ordered and distributed as a single sales item to consumers.
- replacement fasteners and a sealing member such as a gasket or o-ring 56 may be included in the kit for attaching the replacement mechanical stop 48 to housing 14 .
- the kit may not include any or only a single length mechanical stop 48 .
- one or more spacers 54 may be included in the kit for placement between internal flange surface 51 of the existing or the only replacement mechanical stop 48 and an external surface of housing 14 .
- multiple spacers 54 having different thicknesses may be included in the kit.
- a first spacer 54 a may be included in the kit that has a first thickness “T”
- a second spacer 54 b may be included in the kit that has a second thickness “t”.
- a difference in thickness between “T” and “t” may be about 2 mm.
- a service technician may select a specific combination of spacers 54 a and 54 b to fine tune a distance that mechanical stop 48 extends into the actuator bore of housing 14 (i.e., to adjust the minimum tilt angle of swashplate 26 ).
- the disclosed pump finds potential application in any fluid system where responsiveness and performance customization is desirable.
- the disclosed pump finds particular applicability in hydraulic tool systems, especially hydraulic tool system for use onboard mobile machines.
- One skilled in the art will recognize, however, that the disclosed pump could be utilized in relation to other fluid systems that may or may not be associated with hydraulically operated tools.
- the disclosed pump could be utilized in relation to an engine lubrication, cooling, or fueling system.
- driveshaft 12 when driveshaft 12 is rotated, body 16 and plungers 20 disposed within barrels 18 of body 16 may also rotate. As plungers 20 rotate about central axis 24 , spherical ends 34 thereof, riding along angled driving surface 28 may cause plungers 20 to cyclically rise and fall in the axial direction of driveshaft 12 (i.e., to extend into and retract from barrels 18 ). This reciprocating motion may function to draw fluid into pumping chamber 22 and push the fluid from pumping chamber 22 at an elevated pressure.
- the flow rate and/or pressure of the fluid exiting body 16 may be varied to meet demands of the associated circuit (not shown).
- the tilt angle of driving surface 28 may be increased, by moving actuator 42 in the first direction away from the input end of driveshaft 12 .
- the tilt angle may be reduced by moving actuator 42 in the second direction opposite the first. The tilt angle may be reduced until actuator 42 engages mechanical stop 48 .
- the effective extension length “L” of mechanical stop 48 into the bore of actuator 42 may be adjusted. Specifically, mechanical stop 48 may either be removed and replaced with a mechanical stop 48 having a different length, or removed and spacers 54 added to reduce the effective extension length.
- the flow output thereof may be tailored to meet the specific application or operator preferences at hand. Specifically, the minimum flow output of pump 10 may be selectively increased to improve responsiveness or decreased to improve efficiency. And, these adjustments may be easily facilitated with use of the disclosed pump kit.
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Abstract
A pump is disclosed. The pump may have a housing, and at least one pumping mechanism disposed within the housing. The at least one pumping mechanism may have a variable displacement. The pump may also have a plurality of available mechanical stops. Each of the plurality of available mechanical stops may be connectable to the housing and configured the limit a minimum displacement of the at least one pumping mechanism to a different amount.
Description
- The present disclosure claims the right to priority based on U.S. Provisional Patent Application No. 60/960,889 filed Oct. 18, 2007.
- The present disclosure relates generally to a pump and, more particularly, to a pump having multiple minimum flow mechanical stops.
- Hydraulic tool systems typically employ multiple actuators provided with high pressure fluid from a common pump. In order to efficiently accommodate the different flow and/or pressure requirements of the individual actuators, these systems generally include a pump having variable displacement. Based on individual and/or combined flow and pressure requirements, the pump changes a fluid displacement amount to meet demands. When demand is low, the displacement is reduced to conserve energy.
- Typical variable displacement pumps used in hydraulic tool systems are known as swashplate or piston type pumps. This type of pump includes a plurality of pistons held against the driving surface of a tiltable swashplate. A joint such as a ball and socket joint is disposed between each piston and the swashplate to allow for relative movement between the swashplate and the pistons. Each piston is slidably disposed to reciprocate within an associated barrel as the pistons rotate relative to the tilted surface of the swashplate. As each piston is retracted from the associated barrel, low pressure fluid is drawn into that barrel. When the piston is forced back into the barrel by the driving surface of the swashplate, the piston pushes the fluid from the barrel at an elevated pressure.
- The tilt angle of the swashplate is directly related to an amount of fluid pushed from each barrel during a single relative rotation between the pistons and the swashplate. And, based on a restriction of the pump and/or a fluid circuit connected to the pump, the amount of fluid pushed from the barrel during each rotation is directly related to the flow rate and pressure of fluid exiting the pump. Thus, a higher tilt angle equates to a greater flow rate and pressure, while a lower tilt angle results in a lower flow rate and pressure. Similarly, a higher tilt angle requires more power from a driving source to produce the higher flow rates and pressures than does a lower tilt angle. As such, when the demand for fluid is low, the swashplate angle is typically reduced to lower the power consumption of the pump.
- Although efficient, lowering the swashplate angle too low may result in a sluggish hydraulic tool system. That is, when the angle of the swashplate must ramp up through a relatively large angle to produce a demanded flow rate and/or pressure, the time required for that movement may also be large. As such, the pump may be slow to produce a high flow rate and/or pressure when starting at a very low tilt angle. And, in some cases, movement of the hydraulic tool system may not be possible until the pressure of the fluid exiting the pump exceeds a predetermined threshold level. Thus, even after a demand for fluid is transmitted to the pump, the actuators may not immediately be capable of movement.
- One way to improve pump responsiveness is to limit the minimum swashplate angle. For example, U.S. Pat. No. 5,567,123 (the '123 patent) issued to Childress et al. on Oct. 22, 1996 describes a swashplate type pump having a minimum allowable tilt angle. The swashplate angle is inhibited from being reduced below the minimum allowable tilt angle by way of a mechanical stop. That is, the mechanical stop engages the swashplate at the minimum angle to inhibit further reduction. In this manner, some flow from the pump may always be available for use by associated hydraulic actuators and, because the swashplate is always tilted to some degree, the time required to meet high fluid demands may be reduced.
- While the pump of the '123 patent may effectively improve system responsiveness, the improvement may be insufficient or undesired in some situations. That is, based on the application at hand, the minimum swashplate angle may be too low or too high, resulting in low responsiveness or low efficiency. In addition, different machine operators may have preferences regarding the minimum pump flow that are not fully satisfied with a single fixed tilt angle limit.
- The disclosed pump is directed to overcoming one or more of the problems set forth above.
- In one aspect, the present disclosure is directed to a pump. The pump may include a housing, and at least one pumping mechanism disposed within the housing. The at least one pumping mechanism may have a variable displacement. The pump may also include a plurality of available mechanical stops. Each of the plurality of available mechanical stops may be connectable to the housing and configured to limit a minimum displacement of the at least one pumping mechanism to a different amount.
- In another aspect, the present disclosure is directed to a method of pressurizing fluid. The method may include rotating a shaft to force fluid from a pumping chamber. The method may further include replacing a first component with a second component having a different effective length to change a minimum amount of fluid forced from the pumping chamber during a rotation of the shaft.
- In yet another aspect, the present disclosure is directed to a pump kit. The pump kit may include a first mechanical stop connectable to a variable displacement swashplate type pump. The first mechanical stop may be configured to limit a minimum displacement tilt angle of the variable displacement swashplate type pump to a first angle greater than zero relative to a perpendicular of a driveshaft of the variable displacement swashplate type pump. The pump kit may also include at least a second mechanical stop connectable to the variable displacement swashplate type pump. The at least a second mechanical stop may be configured to limit a minimum displacement tilt angle of the variable displacement swashplate type pump to a second angle greater than zero relative to the perpendicular of the driveshaft of the variable displacement swashplate type pump. The pump kit may further include instructions for changing an effective displacement of the variable displacement swashplate type pump.
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FIG. 1 is a diagrammatic illustration of an exemplary disclosed pump; -
FIG. 2 is diagrammatic illustration of an exemplary pumping portion of the pump ofFIG. 1 ; -
FIG. 3 is a cross-sectional illustration of an exemplary mechanical stop for use with the pumping portion ofFIG. 2 ; and -
FIG. 4 is a cross-sectional illustration of another exemplary mechanical stop for use with the pumping portion ofFIG. 2 . -
FIG. 1 illustrates apump 10. In one embodiment,pump 10 may be driven by an external source of power (not shown), such as a combustion engine, via adriveshaft 12. As such,driveshaft 12 may extend from one end of apump housing 14 for engagement with the engine. - As illustrated in
FIG. 2 ,housing 14 may enclose abody 16 defining a plurality of barrels 18 (only one shown).Pump 10 may also include a plurality ofplungers 20, oneplunger 20 slidingly disposed within eachbarrel 18. Eachbarrel 18 and each associatedplunger 20 may, together, at least partially define a pumping chamber 22. It is contemplated that any number of pumping chambers 22 may be included withinbody 16 and symmetrically and radially disposed about acentral axis 24. In the embodiment ofFIG. 2 ,central axis 24 may be coaxial withdriveshaft 12. However, it is contemplated thatcentral axis 24 may be at an angle relative todriveshaft 12 such as in a bent-axis type pump. -
Body 16 may be connected to rotate withdriveshaft 12. That is, asdriveshaft 12 is rotated by the engine,body 16 andplungers 20 located withinbarrels 18 ofbody 16 may all rotate together aboutcentral axis 24. -
Pump 10 may be a swashplate type pump. Specifically, pump 10 may include astationary swashplate 26 having a drivingsurface 28 and atilt frame 30. Drivingsurface 28 may be operatively engaged withplungers 20 by way of a joint 32 such as a ball and socket joint. That is, eachplunger 20 may have a generallyspherical end 34, which is biased into engagement with a cup-like socket 36.Sockets 36 may be configured to slide along drivingsurface 28, which may be fixedly connected to tiltframe 30. -
Swashplate 26 may be tilted to vary a displacement ofplungers 20 withinbarrels 18. Specifically,tilt frame 30 may be situated within a bearingmember 38 and pivotal about atilt axis 40. In one embodiment,tilt axis 40 may pass through and be substantially perpendicular tocentral axis 24. Astilt frame 30 and connected drivingsurface 28 pivot abouttilt axis 40, theplungers 20 located on one half of driving surface 28 (relative to tilt axis 40) may retract into their associatedbarrels 18, while theplungers 20 located on an opposing half of drivingsurface 28 may be extended out of their associatedbarrels 18 by the same amount. Asplungers 20 rotate aboutcentral axis 24,plungers 20 may annularly move from the retracted side of drivingsurface 28 to the extended side, and repeat this cycle asdriveshaft 12 rotates. - As
plungers 20 retract out ofbarrels 18, low pressure fluid may be drawn intobarrels 18. Conversely, asplungers 20 extend intobarrels 18, the fluid may be forced frombarrels 18 at an elevated pressure. An amount of movement between the retracted position and the extended position may relate to a flow rate of fluid displaced byplungers 20 during a single rotation ofdriveshaft 12. Because of the connection betweenplungers 20 and drivingsurface 28, the tilt angle (angle relative to a perpendicular ofcentral axis 24 that results in positive displacement of plungers 20) of drivingsurface 28 may relate to the movement between the retracted position and the extended position. One or more pressure relief valves (not shown) located withinpump 10 or within a hydraulic circuit (not shown) supplied with fluid frompump 10, may affect the pressure of the fluid forced from barrels 18. -
Swashplate 26 may be tilted abouttilt axis 40 by way of anactuator 42.Actuator 42 may be disposed within a bore (not shown) ofhousing 14 and connected to tiltframe 30 by way of anarm 44 protruding from one side oftilt frame 30. Specifically, anactuator bracket 46 may be pivotally connected to protrudingarm 44, and fixedly connected toactuator 42.Actuator 42 may translate linearly in the general direction ofcentral axis 24 to pivottilt frame 30 abouttilt axis 40. For example,actuator 42 may move in a first direction away from an input end ofdriveshaft 12 to increase a tilt angle of drivingsurface 28. Conversely,actuator 42 may move in a second direction toward the input end ofdriveshaft 12 to decrease a tilt angle of drivingsurface 28.Actuator 42 may be powered in any conventional manner, including, among other ways, hydraulically, electrically, pneumatically, and mechanically. - In some situations, it may be desirable to limit a minimum tilt angle of
swashplate 26. For this purpose, pump 10 may include amechanical stop 48 disposed generally coaxially withactuator 42 in the bore ofhousing 14, and connected tohousing 14 by way of one ormore fasteners 50. In this location,mechanical stop 48 may inhibit the motion ofactuator 42 in the second direction such that the resulting tilt angle of drivingsurface 28 ensuresplungers 20 always extend intobarrels 18 to displace fluid during the rotation of driveshaft 12 (i.e.,mechanical stop 48 may always ensure positive displacement of pump 10). The minimum tilt angle ofswashplate 26 may be directly related to the extension distance ofmechanical stop 48 into the actuator bore ofhousing 14. That is, a longermechanical stop 48 may limit the tilt angle ofswashplate 26 to a greater angle, as compared to a shortermechanical stop 48. -
FIG. 3 illustrates one embodiment ofmechanical stop 48. In this example,mechanical stop 48 resembles a plug having an extension length “L”. Extension length “L” may be considered the distance from aninternal flange surface 51 to anend surface 52 that abutsactuator 42. In one embodiment, length “L” may be in the range of about 34-39 mm. A first embodiment ofmechanical stop 48 may have a length “L” of about 34.6 mm. A second embodiment ofmechanical stop 48 may have a length “L” of about 36.6 mm. A third embodiment ofmechanical stop 48 may have a length “L” of about 38.6 mm. - The minimum tilt angle limit of
swashplate 26 may be related to a responsiveness ofpump 10. That is, a greater amount of time required forswashplate 26 to move from the minimum tilt angle to a desired tilt angle may result in a slow or sluggish pump. In contrast, a lower amount of time required forswashplate 26 to move from the minimum tilt angle to a desired tilt angle may result in a responsive pump. As movement ofactuator 42 may be substantially constant, the time required for the movement ofswashplate 26 may be directly related to the angular distance between the minimum tilt angle and the desired tilt angle. Thus, for a given desired tilt angle, a lower minimum tilt angle may require more movement time and, thus, result in a less responsive pump, as compared to a greater minimum tilt angle. - The minimum tilt angle limit of
swashplate 26 may also relate to an efficiency ofpump 10. That is, a greater minimum tilt angle of drivingsurface 28 may displaceplungers 20 further intobarrels 18 to pressurize a greater amount of fluid per revolution ofdriveshaft 12 during a standby condition, as compared to a lower minimum tilt angle. Thus, at the greater minimum tilt angle, the powersource driving pump 10 may be loaded to a greater degree to pressurize a greater amount of unused fluid (the pressurized fluid may be substantially unused and drained to a low pressure tank during standby conditions). For this reason, a greater minimum tilt angle may result in a lower efficiency ofpump 10 and the powersource driving pump 10. - In some applications one of responsiveness and efficiency may be more important than the other. That is, in a first situation, responsiveness at the cost of efficiency may be desirable, while in a second situation, efficiency may be much more important than responsiveness. In the first situation, the
mechanical stop 48 having the length “L” of 34.6 mm may be optimal. However, in the second situation, themechanical stop 48 having the length “L” of 38.6 mm may be optimal. Thus, the length “L” may be selected for use based on an intended application ofpump 10 and/or amachine incorporating pump 10. Alternatively, the length “L” may be chosen based on an operator preference. - To accommodate the different applications and/or operator preferences described above, a pump adjustment kit may be created having multiple mechanical stops 48. This kit may include one
mechanical stop 48 of each length “L”. In addition, the kit may include instructions for removing the existingmechanical stop 48 and inserting a replacementmechanical stop 48 having a different length. The kit may have a single part number, meaning that the kit can be ordered and distributed as a single sales item to consumers. In some embodiments, replacement fasteners and a sealing member such as a gasket or o-ring 56 may be included in the kit for attaching the replacementmechanical stop 48 tohousing 14. - In an alternative embodiment illustrated in
FIG. 4 , the kit may not include any or only a single lengthmechanical stop 48. In order to vary the minimum tilt angle ofswashplate 26, one ormore spacers 54 may be included in the kit for placement betweeninternal flange surface 51 of the existing or the only replacementmechanical stop 48 and an external surface ofhousing 14. In one embodiment,multiple spacers 54 having different thicknesses may be included in the kit. For example, afirst spacer 54 a may be included in the kit that has a first thickness “T”, while asecond spacer 54 b may be included in the kit that has a second thickness “t”. In one embodiment, a difference in thickness between “T” and “t” may be about 2 mm. In this manner, a service technician may select a specific combination ofspacers mechanical stop 48 extends into the actuator bore of housing 14 (i.e., to adjust the minimum tilt angle of swashplate 26). - The disclosed pump finds potential application in any fluid system where responsiveness and performance customization is desirable. The disclosed pump finds particular applicability in hydraulic tool systems, especially hydraulic tool system for use onboard mobile machines. One skilled in the art will recognize, however, that the disclosed pump could be utilized in relation to other fluid systems that may or may not be associated with hydraulically operated tools. For example, the disclosed pump could be utilized in relation to an engine lubrication, cooling, or fueling system.
- Referring to
FIG. 2 , whendriveshaft 12 is rotated,body 16 andplungers 20 disposed withinbarrels 18 ofbody 16 may also rotate. Asplungers 20 rotate aboutcentral axis 24, spherical ends 34 thereof, riding along angled drivingsurface 28 may causeplungers 20 to cyclically rise and fall in the axial direction of driveshaft 12 (i.e., to extend into and retract from barrels 18). This reciprocating motion may function to draw fluid into pumping chamber 22 and push the fluid from pumping chamber 22 at an elevated pressure. - During operation of
pump 10, the flow rate and/or pressure of thefluid exiting body 16 may be varied to meet demands of the associated circuit (not shown). To increase the flow rate and/or pressure of the discharged fluid, the tilt angle of drivingsurface 28 may be increased, by movingactuator 42 in the first direction away from the input end ofdriveshaft 12. Conversely, to decrease the flow rate and/or pressure of the discharged fluid, the tilt angle may be reduced by movingactuator 42 in the second direction opposite the first. The tilt angle may be reduced untilactuator 42 engagesmechanical stop 48. - To vary the minimum tilt angle limit of
pump 10, the effective extension length “L” ofmechanical stop 48 into the bore ofactuator 42 may be adjusted. Specifically,mechanical stop 48 may either be removed and replaced with amechanical stop 48 having a different length, or removed andspacers 54 added to reduce the effective extension length. - Because of the adjustability of
pump 10, the flow output thereof may be tailored to meet the specific application or operator preferences at hand. Specifically, the minimum flow output ofpump 10 may be selectively increased to improve responsiveness or decreased to improve efficiency. And, these adjustments may be easily facilitated with use of the disclosed pump kit. - It will be apparent to those skilled in the art that various modifications and variations can be made to the pump of the present disclosure. Other embodiments of the pump will be apparent to those skilled in the art from consideration of the specification and practice of the pump disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
Claims (20)
1. A pump, comprising:
a housing;
at least one pumping mechanism disposed within the housing and having a variable displacement; and
a plurality of available mechanical stops, each of the plurality of available mechanical stops connectable to the housing and configured the limit a minimum displacement of the at least one pumping mechanism to a different amount.
2. The pump of claim 1 , further including a tiltable swashplate disposed within the housing and biased into engagement with the at least one pumping mechanism, wherein each of the plurality of available mechanical stops is configured to limit a minimum tilt angle of the swashplate.
3. The pump of claim 2 , wherein the at least one pumping mechanism includes a plurality of plungers reciprocatingly disposed within a plurality of barrels, wherein the plurality of available mechanical stops affects a relative movement between the plurality of plungers and the plurality of barrels.
4. The pump of claim 3 , wherein the plurality of plungers are radially arranged about a common axis and configured to rotate about the axis relative to the swashplate.
5. The pump of claim 1 , further including an actuator configured to tilt the swashplate to an angle corresponding to a demand for fluid.
6. The pump of claim 5 , wherein each of the plurality of available mechanical stops is configured to limit movement of the actuator.
7. The pump of claim 5 , wherein the actuator is hydraulically actuated.
8. The pump of claim 1 , wherein each of the plurality of available mechanical stops corresponds with a different application of the pump.
9. The pump of claim 1 , wherein each of the plurality of available mechanical stops corresponds with an operator preference relating to responsiveness and efficiency.
10. The pump of claim 1 , wherein each of the plurality of available mechanical stops ensure that some fluid is always being displaced by the at least one pumping mechanism.
11. The pump of claim 1 , wherein the plurality of available mechanical stops includes:
a plug; and
at least one spacer configured to limit an extension of the plug into the housing.
12. The pump of claim 11 , wherein the at least one spacer includes a plurality of spacers, and the minimum displacement of the at least one pumping mechanism is limited based on the number of the plurality of spacers connected between the plug and the housing.
13. The pump of claim 12 , wherein the plurality of spacers have different thicknesses, and the minimum displacement of the at least one pumping mechanism is limited based further in on the thickness of the plurality of spacers connected between the plug and the housing.
14. The pump of claim 13 , wherein the plurality of spacers includes at least two spacers having a different in thickness of about 2-4 mm.
15. The pump of claim 1 , wherein the plurality of mechanical stops includes at least two mechanical stops having a difference in length of about 2-4 mm.
16. A method of pressurizing fluid, comprising:
rotating a shaft to force fluid from a pumping chamber; and
replacing a first component with a second component having a different effective length to change a minimum amount of fluid forced from the pumping chamber during a rotation of the shaft.
17. The method of claim 16 , wherein replacing the first component includes adding a spacer between the first component and a pump housing.
18. The method of claim 16 , wherein replacing a first component with a second component having a different effective length changes a tilt angle of a driving surface.
19. The method of claim 18 , wherein replacing a first component with a second component having a different effective length limits motion of an actuator connected to the driving surface.
20. A pump kit, comprising:
a first mechanical stop connectable to a variable displacement swashplate type pump, and being configured to limit a minimum tilt angle of the variable displacement swashplate type pump to a first angle greater than zero relative to a perpendicular of a driveshaft of the variable displacement swashplate type pump;
at least a second mechanical stop connectable to the variable displacement swashplate type pump and being configured to limit a minimum tilt angle of the variable displacement swashplate type pump to a second angle greater than zero relative to the perpendicular of the driveshaft of the variable displacement swashplate type pump; and
instructions for changing an effective displacement of the variable displacement swashplate type pump.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/285,819 US20090104047A1 (en) | 2007-10-18 | 2008-10-15 | Pump having multiple minimum flow mechanical stops |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US96088907P | 2007-10-18 | 2007-10-18 | |
US12/285,819 US20090104047A1 (en) | 2007-10-18 | 2008-10-15 | Pump having multiple minimum flow mechanical stops |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090104047A1 true US20090104047A1 (en) | 2009-04-23 |
Family
ID=40563671
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/285,819 Abandoned US20090104047A1 (en) | 2007-10-18 | 2008-10-15 | Pump having multiple minimum flow mechanical stops |
Country Status (1)
Country | Link |
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US (1) | US20090104047A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9163649B2 (en) | 2012-10-16 | 2015-10-20 | General Electric Company | Mechanical stop adjustment for jack |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3522759A (en) * | 1968-07-26 | 1970-08-04 | Cessna Aircraft Co | Pump or motor device |
US4142841A (en) * | 1977-08-31 | 1979-03-06 | Parker-Hannifin Corporation | Variable displacement pump control |
US5567123A (en) * | 1995-09-12 | 1996-10-22 | Caterpillar Inc. | Pump displacement control for a variable displacement pump |
US5749709A (en) * | 1996-05-15 | 1998-05-12 | Du; Benjamin R. | Positive displacement pump including modular pump component |
US20050121249A1 (en) * | 2003-01-08 | 2005-06-09 | Koji Iwaki | Hydraulic axle-drive device |
US7114432B1 (en) * | 2005-02-09 | 2006-10-03 | Sauer-Danfoss Inc. | Torque limiting device for hydraulic piston pump |
-
2008
- 2008-10-15 US US12/285,819 patent/US20090104047A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3522759A (en) * | 1968-07-26 | 1970-08-04 | Cessna Aircraft Co | Pump or motor device |
US4142841A (en) * | 1977-08-31 | 1979-03-06 | Parker-Hannifin Corporation | Variable displacement pump control |
US5567123A (en) * | 1995-09-12 | 1996-10-22 | Caterpillar Inc. | Pump displacement control for a variable displacement pump |
US5749709A (en) * | 1996-05-15 | 1998-05-12 | Du; Benjamin R. | Positive displacement pump including modular pump component |
US20050121249A1 (en) * | 2003-01-08 | 2005-06-09 | Koji Iwaki | Hydraulic axle-drive device |
US7114432B1 (en) * | 2005-02-09 | 2006-10-03 | Sauer-Danfoss Inc. | Torque limiting device for hydraulic piston pump |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9163649B2 (en) | 2012-10-16 | 2015-10-20 | General Electric Company | Mechanical stop adjustment for jack |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: CATERPILLAR INC., ILLINOIS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BAUS, JOHN D.;PAYNE, WESLEY T.;REEL/FRAME:021747/0094 Effective date: 20081002 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |