Patent Grant
9638188
This invention relates to a hydraulic machine. In particular, the invention relates to a hydraulic machine that may be used as a rotary vane pump or a rotary vane motor.
Hydraulic vane pumps are used to pump hydraulic fluid in many different types of machines for different purposes. Such machines include, for instance, earth moving, industrial and agricultural machines, waste collection vehicles, fishing trawlers, cranes, and vehicle power steering systems.
Hydraulic vane pumps typically have a housing with a chamber formed therein. A rotor is rotatably mounted in the housing. The rotor is typically of generally cylindrical shape and the chamber has a shape such that one or more rise and fall regions are formed between the walls of the rotor and the walls of the chamber. In the rise regions, a relatively large space opens between the outer wall of the rotor and the inner wall of the chamber. On the leading side of the rise region, there exists a region which is substantially a dwell, although in usual practice there exists a small amount of fall. This is sometimes called a major dwell or major dwell region. The major dwell is followed by a fall region, in which the space between the rotor and the chamber decreases. Outside of the rise, fall and major dwell regions, the space between the outer wall of the rotor and the inner wall of the chamber is small. In practice, this is usually a true dwell of zero vane extension and is sometimes called the minor dwell. The rotor normally has a number of slots and movable vanes are mounted in the slots. As the rotor rotates, centrifugal forces cause the vanes to move to an extended position as they pass through the rise regions. As the vanes travel along the fall regions, the vanes are forced to move to a retracted position by virtue of the rotors contacting the inner wall of the chamber as they move into the region of restricted clearance between the rotor and chamber. Hydraulic fluid lubricates the vanes and the inner wall of the chamber.
Hydraulic vane pumps are usually coupled to a drive, such as to a rotating output shaft of a motor or an engine and, in the absence of expensive space invasive clutches or other disconnecting means, continue to pump hydraulic fluid as long as the motor or engine continues to operate. A rotor of the pump also usually has a rotational speed determined by the rotational speed of the motor or engine.
A problem with known hydraulic vane pumps is that they continuously pump hydraulic fluid, regardless of whether or not a hydraulic system of a machine is being utilised in a working mode of the machine. That is, a machine may be idle or may be in the process of being driven from one job location to another (i.e. in a non-working mode), yet the pump may continue to consume energy in pumping fluid excessively or unnecessarily.
A related problem is that hydraulic hoses, pipes and valves of hydraulic systems of machines such as waste collectors and hydraulic cranes tend to be larger than actually required in order for the machines to carry out lifting in their working mode. That is, lifting may be normally carried out at moderate engine speeds, yet the machines may attain high engine speeds when being driven from one location to another. Consequently, larger and more expensive hydraulic hoses, pipes and valves are required in order to accommodate the higher fluid pressures generated by the pump at high engine speeds.
A problem with some known hydraulic vane motors is that, like with hydraulic vane pumps, in the absence of expensive space invasive clutches or other disconnecting means, hydraulic vane motors may also be worked by the hydraulic fluid incessantly and excessively.
U.S. Pat. No 3,421,413 to Adams et al describes a sliding vane pump in which hydraulic pressure is applied to each vane in order to maintain the vanes in optimum engagement with a cam surface that encircles the rotor which carries the vanes. This patent is directed towards ensuring that the vanes remain in optimum contact with the encircling cam.
U.S. Pat. No. 3,586,466 to Erickson describes a rotary hydraulic motor having a slotted rotor and a movable vane located in each slot. The rotor is journalled in a chamber that defines three circumferentially spaced crescent-shaped pressure chamber sections. The hydraulic motor includes a valve control means and associated passages to be able to selectively control the flow of pressurised fluid to the pressure chamber sections. This allows pressurised fluid to be supplied to one, two or all three pressure chamber sections. When pressurised fluid is delivered to all three pressure chamber sections, low speed, high torque operation occurs. When pressurised fluid is delivered to two pressure chamber sections, higher speed but lower torque operation occurs. When pressurised fluid is delivered to only one pressure chamber section, even higher speed but lower torque operation of the motor occurs.
The hydraulic motor of Erickson also includes an arrangement of passages that allow pressurised fluid to impart radially outward movement to the vanes adjacent the inlet passages to the pressurized chamber sections and to impart radially inward movement to the vanes adjacent the outlet passages of the pressurized chamber sections. Thus, each vane is fluid pressure urged radially outwardly into sealing engagement with the concavity or concave surface of each pressurized chamber section during initial movement of the vane circumferentially across the pressurize chamber section, the vane being moved radially inwardly by fluid pressure at the circumferentially opposite end of the pressurized chamber section, to reduce the frictional load between each vane and the inner peripheral surface portions of the chamber at areas wherein there is little or no circumferential pressure applied to the vanes (see column 4, lines 55 to 72).
The entire contents of U.S. Pat. Nos. 3,421,413 and 3,586,466 are expressly incorporated herein by cross reference.
It is therefore an object of the present invention to provide a hydraulic machine that overcomes or minimises at least one of the problems referred to above, or to provide the public with a useful or commercial choice.
According to a first aspect, the present invention provides a hydraulic machine having:
a body having a chamber,
an inlet for introducing hydraulic fluid into the chamber,
an outlet through which hydraulic fluid leaves the chamber,
a rotor rotatable within the chamber,
the chamber and the rotor being shaped to define one or more rise, fall and dwell regions between walls of the chamber and the rotor,
a shaft extending from the rotor,
the rotor having a plurality of slots,
a plurality of vanes located such that each slot of the rotor has a vane located therein,
each vane being movable between a retracted position and an extended position wherein in the retracted position, the vane is unable to work the hydraulic fluid introduced into the chamber and in the extended position the vane is able to work the hydraulic fluid introduced into the chamber, and
vane retaining means being selectively actuable such that, when activated, the vane retaining means retains the vanes in the retracted position.
Preferably, the hydraulic machine further comprises an under vane passage for selectively receiving pressurised hydraulic fluid to facilitate moving the vanes located in a dwell region from the retracted position to the extended position. Although the vanes of a hydraulic pump are likely to automatically move from the retracted position to the extended position as they enter a rise region after inactivation of the vane retaining means, use of an under vane passage to supply pressurised hydraulic fluid to under the vanes will assist in this movement and also minimise the likelihood of a vane sticking in the retracted position. For hydraulic motors, inclusion of under vane passages can be used to actively drive the vanes to the extended position. Conventional hydraulic motors use springs to drive the vanes to the extended position. The under vane passages can either complement or replace such springs.
The under vane passage may also function to allow hydraulic fluid located under the vanes to drain away from under the vanes as the vanes move from the extended position to the retracted position.
In some instances, the vanes may have a vane pin located underneath each vane. The vane pins typically can move in a vane pin duct. In such embodiments, the under vane passage may include a passage located under the vane pin.
Preferably, the vane retaining means can be selectively actuated to retain all of the vanes in the retracted position. Preferably, the vane retaining means can retain the vanes in the retracted position for at least an entire revolution of the rotor.
The inlet may be branched and may have one or more openings into the chamber, adjacent a start of each rise region. An end of the inlet at a periphery of the body may be attached to a hydraulic line.
The outlet may be branched and may have one or more openings from the chamber, adjacent an end of each fall region. An end of the outlet at a periphery of the body may be attachable to a hydraulic line.
The under vane passages may extend from under each of the vanes to the outlet and the under vane passages may be pressurised with hydraulic fluid from the outlet. Alternatively, the under vane passages may be pressurised with pressurised hydraulic fluid from a pilot source of pressurised hydraulic fluid.
The under vane passage may also communicate with the inlet such that when the vane retaining means is actuated, hydraulic fluid drained from under the vanes is directed to the inlet, to allow the vanes to be retained in the retracted position. In other embodiments, the outlet chamber may be vented when the vanes are retracted (as the vanes are no longer working the hydraulic fluid) to enable under vane fluid to be vented to the outlet. In this embodiment, the under vane passages are indirectly placed into communication with the inlet because venting the outlet chamber to the inlet chamber also effectively vents the under vane passages to the inlet chamber. In embodiments where the vane pump or motor includes an intravane and an undervane passage, the under vane passage may be connected to the pumping chamber and the intra vane may be connected to the outlet. When the outlet chamber is vented to the inlet chamber, the under vane and intra vane is also vented to the inlet chamber, This may be done just before the vanes are clamped for smooth operation.
A control valve, such as a pressure sensitive spring loaded spool valve, may be located within the under vane passage or in fluid communication with the under vane passages. The control valve may direct hydraulic fluid from the outlet to under the vanes when the vane retaining means is not actuated, and may direct hydraulic fluid from under the vanes to the inlet when the vane retaining means is actuated.
The vane retaining means is selectively actuable to retain the vanes in the retracted position. The vane retaining means suitably utilises pressurised hydraulic fluid to retain the vanes in the retracted position. In one embodiment, the vane retaining means comprises an engagement member movable between a disengaged position and an engaged position in which the engagement member contacts the vane to retain the vane in the retracted position. The engagement member may be an engagement pin or an engagement ball that engages with a side wall of the vane. More preferably, the engagement member is an engagement pin or an engagement ball that engages with a recess in the vane to retain the vane in the retracted position.
In another embodiment, the vanes may be affixed to the rotor by a vane pin, which vane pin moves with the vane as the vane moves between the retracted and extended positions and the engagement member may be an engagement pin or ball that engages with the vane pin to thereby retain the vane in the retracted position.
The engagement member is suitably moved from the disengaged position to the engaged position by pressurised hydraulic fluid. The pressurised hydraulic fluid may be selectively applied to the engaging means when it is desired to retain the vanes in the retracted position.
The engagement member may be provided with a biasing means, such as a return spring, to disengage the engagement member when maintaining the vanes in the retracted position is no longer required. Alternatively, hydraulic pressure may be used to move the engagement member to a disengaged position. As a further alternative, the engagement member may be arranged such that centrifugal forces cause the engagement member to move to the disengaged position when the engagement member is inactivated.
In another embodiment, the vane retaining mean comprises a vane retaining passage for receiving pressurised hydraulic fluid, the vane retaining passage directing the pressurised hydraulic fluid to at least one face of the vane such that the pressurised hydraulic fluid forces (i.e. clamps) the vane against at least one face of the respective slot. For instance, a respective groove extending longitudinally along a radially extending face of each vane may provide a section of the vane retaining passage, a respective groove extending along a radially extending face of each slot may provide a section of the vane retaining passage, or the vane retaining passage may extend through the rotor and direct hydraulic fluid onto a radially extending face of each vane. The vane retaining passage may extend from each of the vanes to a port at a periphery of the body. The port may be attached to a hydraulic line.
Preferably, concentric annular sections of the vane retaining passage and under vane passage communicate hydraulic fluid to each of the vanes.
In one mode of operation, the hydraulic machine may function as a pump. In another mode of operation the hydraulic machine may function as a motor. When operated as a pump, the drive shaft may be coupled to an output shaft of an engine or motor. The slotted rotor may be splined to fit the drive shaft. When operated as a motor, the drive shaft may be coupled to another hydraulic machine such as a pump.
The machine may have any suitable number of vanes and preferably the machine has 10 or 12 vanes. The vanes may be of any suitable shape and size. Each vane may have an enlarged base, each slot may have an enlarged portion within which the base may move when the vane is extending or retracting, and each slot may have a restriction through which the base may not move when the vane is extending.
The machine may have a safety pressure relief valve, a solenoid valve (mechanically, piloted or electrically actuated) for selecting whether the pump vanes are to be retained in the retracted position or not, and a pressure responsive shuttle valve.
The machine may have features of known hydraulic vane pumps or motors, such as the Vickers® V10 or V20 or VMQ series of rotary vane pumps. For instance, the body may have ball bearings and bushings for supporting opposing ends of the drive shaft and to centre the slotted rotor within the chamber. The body may comprise two or more attachable pieces. An O-ring may be used to provide a fluid tight seal when connecting the body pieces together.
Any suitable type of hydraulic fluid may be used. Pilot values of three to four liters per minute and 10 to 15 bar pressure may be suitable for pressurising the vane retaining passage, to clamp the vanes and to activate the control valve such that hydraulic fluid from under the vanes is directed to the inlet.
According to a second aspect of the present invention, there is provided a method for retaining vanes of a hydraulic vane pump or motor in a retracted position within a slotted rotor of the pump or motor, the pump or motor including a chamber and a rotor mounted for rotation within the chamber, the chamber and the rotor being shaped to define one or more rise, fall and dwell regions between walls of the chamber and the rotor, the rotor having a plurality of slots and a plurality of vanes located such that each slot of the rotor has a vane located therein, each vane being movable between a retracted position and an extended position wherein in the retracted position, the vane is unable to work the hydraulic fluid introduced into the chamber and in the extended position the vane is able to work the hydraulic fluid introduced into the chamber wherein the method includes the steps of:
operating the pump or motor such that the vanes move to the extended position when passing through the rise regions and the vanes move towards or into the retracted position when passing along the fall regions and selectively actuating vane retaining means to retain the vanes in the retracted position.
Suitably, the vanes are retained in the retracted position by the vane retaining means for at least an entire revolution of the rotor.
Preferably, the method further includes the step of draining hydraulic fluid from under the vanes as the vanes move towards the retracted position. In some instances, the vanes may be provided with vane pins positioned under the vanes and the step of draining hydraulic fluid from under the vanes includes draining hydraulic fluid from under the vane pins.
The method may further include releasing the retaining means to allow the vanes to move to the extended position as the vanes enter the rise regions.
Most suitably, the method comprises applying hydraulic fluid pressure to activate the vane retaining means to retain each of the vanes in the retracted position.
In a third aspect, the present invention provides a hydraulic machine comprising a body having a chamber, a rotor rotatable within the chamber, the chamber and the rotor being shaped to define one or more rise, fall and dwell regions between the walls of the chamber and the rotor, the rotor having a plurality of slots, a plurality of vanes located such that each slot of the rotor has a vane located therein, each vane being moveable between a retracted position and an extended position wherein in the retracted position the vane is unable to work the hydraulic fluid introduced into the chamber and in the extended position the vane is able to work the hydraulic fluid introduced into the chamber, an inlet for introducing hydraulic fluid into the chamber, an outlet through which hydraulic fluid leaves the chamber, and vane retaining means being selectively actuable to retain the vanes in the retracted position and selectively actuable to release the vanes and allow the vanes to move from the retracted position to the extended position, wherein the vane retaining means comprises moveable engagement means to move between a retaining position and a non-retaining position, and moveable actuating means moveable between a first position and a second position wherein the moveable engagement means are forced to move from a non-retaining position to a retaining position by movement of the moveable actuation means between the first position and the second position.
The moveable actuation means may be of any suitable size, shape and construction. Suitably, each moveable actuation means comprises a spool having a region of relatively large cross sectional area and a region of relatively small cross sectional area with the regions of relatively large cross sectional area and relatively small cross sectional area being connected by a ramped or sloping portion. The moveable engagement means can move to the non-retaining position when the relatively small cross sectional region of the moveable actuation means contacts the moveable engagement means. The moveable engagement means is forced to move to the retaining position when the relatively larger cross sectional area region contacts the moveable engagement means.
Preferably, pressurised hydraulic fluid (oil) is used to move the moveable actuation means in at least one direction. Preferably, a spring causes the moveable actuation means to move in the opposite direction once pressurised hydraulic fluid has been removed from the moveable actuation means. Suitably, the moveable actuation means moves between the first position (in which the vanes are not retained) and the second position (in which the vanes are retained) by virtue of applied pressurised hydraulic fluid.
The spool suitably has a region of relatively smaller diameter and a region of relatively larger diameter, with the two regions being connected by a generally frustoconical region having sloped or ramped side walls.
The moveable engagement means may be of any suitable size, shape and construction. Each moveable engagement means may comprise, for instance, at least one ball, pin, plate or other type of retaining member which detents into a hole formed in a side of the vane. The moveable engagement means suitably comprises two small balls, more suitably one small ball, which detent into a hole formed in a side of the vane.
In another aspect, the present invention provides a hydraulic machine comprising a body having a chamber, an inlet for introducing hydraulic fluid into the chamber, an outlet through which hydraulic fluid leaves the chamber, a rotor rotatably mounted within the chamber, the chamber and the rotor being shaped to define one or more rise regions, fall regions and dwell regions between walls of the chamber and the rotor, a shaft extending from the rotor, the rotor having a plurality of slots, a plurality of vanes located such that each slot of the rotor has a vane located therein, each vane being movable between a retracted position and an extended position wherein in the retracted position, the vane not working the hydraulic fluid introduced into the chamber and in the extended position the vane working the hydraulic fluid introduced into the chamber, vane retaining means being selectively actuable such that, when actuated, the vane retaining means retains the vanes in the retracted position, said vane retaining means being arranged such that pressurised hydraulic fluid actuates the vane retaining means to retain the vanes in the retracted position or pressurised hydraulic fluid deactivates the vane retaining means such that the vanes move from the retracted position to the extended position, and under vane passages for draining fluid from under the vanes when the vanes move from the extended position to the retracted position, wherein the rotor comprises a first rotor part joined to a second rotor part, one or both of the first rotor part and the second rotor part defining fluid flow passages for providing pressurised hydraulic fluid to the vane retaining means, one or both of the first rotor part and the second rotor part defining vane retaining means movement passages, said vane retaining means being located in said vane retaining means movement passages wherein said vane retaining means move in said vane means movement passages between a retaining position and a non-retaining position.
In yet a further aspect, the present invention provides method for manufacturing a rotor for use in the hydraulic machine as described herein, the method comprising providing a first rotor part and a second rotor part, machining fluid flow passages for providing pressurised hydraulic fluid to the vane retaining means or to the under vane region or to the intra vane region in one or both of the first rotor part and the second rotor part, machining faint retaining means movement passages in one or both of said first rotor part and said second rotor part, positioning vane retaining means in the vane retaining means movement passages, and joining the first rotor part to the second rotor part to thereby form the rotor.
In some embodiments, the fluid flow passages for providing pressurised hydraulic fluid are machined in one of the first rotor part the second rotor part and the vane retaining means movement passages comprise passages machined in the first rotor part and the second rotor part. In some embodiments, the method further comprises providing dowel holes in the first rotor part and the second rotor part, inserting dowels in the dowel holes, dowelling the first rotor part and the second rotor part together and welding or bonding the first rotor part in the second rotor part together.
The vane retaining means may comprise a plurality of spools that move one or more balls into contact with a side wall of the vanes, the spools including a ramped portion and the method may comprise positioning the spools in the vane retaining means movement passages and positioning one or more balls adjacent the ramped portion of the spools, and subsequently joining the first rotor part to the second rotor part.
Preferred embodiments of the invention will now be described by way of reference to the accompanying drawings in which:
In the figures, like reference numerals refer to like features. In moving vane hydraulic machines, normal operation requires venting of under vane fluid. There are numerous such venting arrangements know to the person skilled in the art and the hydraulic machines in accordance with the present invention may incorporate any known under vane venting technologies. Such under vane venting is not part of the inventive concept of the present invention and need not be described in great detail
The housing 12 defines an inlet chamber 24 that receives hydraulic fluid via inlet 20.
A drive shaft 26 is journaled into housing 12 by bearings 28. The drive shaft includes a splined section 30. The splined section of the driveshaft 26 is in fluid communication with the inlet of the hydraulic machine. Thus, the splined section of the driveshaft is a region containing low pressure hydraulic fluid. The splined section 30 of the drive shaft 26 is splined into a complementary spline formed or press fitted into an opening through a rotor (not shown) inside ring 32. Further details of the rotor will be provided with reference to the other drawings attached to this specification. Ring 32 defines a chamber that will be described in more detail in later Figures and a rotor (hidden in
The housing 12 includes a pilot line entry 42 in the form of a nipple that allows a pilot line to be connected thereto. The pilot line entry 42 is provided to enable pressurised hydraulic fluid to travel down the pilot line into the housing. The pilot line 42 is in fluid communication with a fluid slot 44 formed in the pressure plate 36. Although
The pump 50 shown in
A rotor 60 is rotatably mounted within the chamber defined by chamber walls 54. Rotor 60 is of generally cylindrical shape. As the rotor 60 is generally cylindrical, and as the chamber defined by chamber walls 54 is generally elliptical, two rise regions 61,63, two major dwell regions 62, 64 and two fall regions 63,65 are formed in the space between the outer walls of the rotor 60 and the chamber walls 54. In the major dwell regions 62, 64, a significant space exists between the outer walls of the rotor 60 and the chamber walls 54. Outside of the major dwell regions 62, 64, the clearance between the wall of the chamber and the rotor 60 is either expanding or decreasing. However, along the minor dwell regions 67, 69, there is only a small clearance between the wall of the rotor 60 and the chamber wall 54. This is well known and is conventional in the sliding vane pump and motor art.
The body 52 includes two hydraulic fluid inlets 70, 72 through which hydraulic fluid passes into entry to the rise regions 61, 63. The body also includes fluid outlets at 66, 68 through which pressurised hydraulic fluid leaves the fall regions of the chamber.
A drive shaft 82 is splined to rotor 60. In this regard, rotor 60 has a central passage passing therethrough. An appropriate spline connection is fitted into the passage passing through the rotor 60, for example by press fitting, or the spline is formed on the passage, to enable the splined drive shaft 82 to be splined to the rotor.
The rotor 60 has a plurality of radially extending slots, some of which are referred to by reference numeral 84. Radial slots 84 each house a vane 86. Respective vane pins 87 are positioned under the vanes 86. In conventional pumps that are generally similar to that shown in
When the vane is free to move in its slot, i.e. extend or retract, the vane can work the hydraulic fluid as necessary. If the hydraulic machine is being used as a pump, the collapsing chamber volume associated with the fall regions and the system resistance act to pressurise the hydraulic fluid. If the hydraulic machine is being used as a motor, the hydraulic fluid is pumped through the chamber and the hydraulic fluid interacts with the extended vanes to cause the rotor to rotate.
In conventional hydraulic machines of the general type similar to that shown in
The present inventor has realised that significant efficiency gains can be made if the vanes can be held in the retracted position (or slightly below the minor dwell diameter) throughout the entire rotation of the rotor if working of the hydraulic fluid by the vanes is not required. To this end, the present inventor has proposed that the hydraulic machine be provided with retaining means for selectively retaining the vanes in the retracted position. The retaining means are capable of retaining the vanes in the retracted position even as the vanes pass through the rise regions, the major dwell regions and the fall regions. The retaining means are also selectively actuable. In the embodiment shown in
If it is desired to retain the vanes in the retracted position, a signal may be sent to a control valve to pass pressurised fluid through the pilot feed line. When the end of passageway 96 comes into register with slot 98, pressurised fluid enters passageway 96 and travels along passageway 96 and into passage 90. The pressurised hydraulic fluid then pushes the engagement pin 88 into engagement with the side of the vane 86. As best shown in
Whilst the pilot line is supplying pressurised hydraulic fluid to the slot 98, the vanes 86 will remain in the retracted position for the entire revolution of the rotor 60.
When supply of the pressurised pilot fluid to the slot 98 is ceased, and preferably the slot 98 is placed in fluid communication with low pressure hydraulic fluid as the ends of passageways 96 come into register with slot 98, the pressurised hydraulic fluid in passageways 96 and 90 is released in those passageways. Consequently, the pressurised fluid no longer acts on engagement pin 88. Return spring 100 (see
Although the vanes will typically move from the retracted position to the extended position automatically, by virtue of centrifugal force caused by rotation of the rotor, when the engagement pins 88 are withdrawn, it may be advantageous to provide some means to assist in or facilitate movement of the vanes from the retracted position to the extended position. In usual practice, such means takes the form of hydraulic pressure acting on a vane or, more frequently, on a pin which then acts on a vane. For example, an oil gallery 102 may be provided around the drive shaft (see
In normal use of the hydraulic machine shown in
When it is desired to maintain the vanes in the retracted position, the control system associated with the hydraulic machine supplies pressurised pilot hydraulic fluid to slot 98 which, in turn, activates the retaining means as described above. As the vanes are retracted by rotation through the fall regions, the engagement pins 88 are activated to retain the vanes in the retracted position.
When it is desired to operate the hydraulic machine such that the vanes work the hydraulic fluid as they pass through the rise and fall regions, the engagement pins 88 are disengaged
Part 220 has an outlet 223 that is threaded for attachment to a hydraulic line (not shown). Outlet 223 communicates with branched fluid passages 205a, 205b which, in turn, communicate with kidney shaped openings 222a, 222b. Openings 222a, 222b are positioned in register with respective openings 205 on the pump assembly 201 shown in
Since the chamber 203 is elliptical and the rotor is generally cylindrical, the space between the inner wall of the chamber and the outer wall of the rotor defines two lobes that form the rise, fall and major dwell regions 260a and 260b (see
A spool valve 250 is provided to allow venting of the under vane pressure by allowing passage 232 to communicate with inlet recess 224b when it is desired to retain the vanes in the retracted position. This is achieved by pilot pressure from pilot inlet 216 passing along passage 242 and exciting spool valve 250 to allow fluid communication between passage 232 and inlet recess 224b. When pilot pressure is released, spring return 234 returns spool valve to a position where passage 232 is in fluid communication with pressurised fluid. As will be understood, this also disconnects fluid communication between passage 232 and recess 224b. The machine shown in
The machine has a communication gallery 240 for selectively delivering hydraulic fluid to the vane retaining passage 241 (shown in
When the vane retaining passage 241 is pressurised, hydraulic fluid is directed to a face of the vane 208 and forces the vane 208 against one or more surfaces defining the slot 209. This retains the vanes in the retracted position. More specific details of how the vanes are retained in the retracted position will now be described with reference to
In one embodiment shown in
In one mode of operation the hydraulic machine may be used as a pump. In another mode of operation the hydraulic machine may be used as a motor.
A hydraulic circuit showing how the machine may be used as a pump is shown in
In order to turn the pump on such that fluid may be circulated, pilot hydraulic fluid is directed by solenoid valve 281 (V2) (in a spring offset mode) to under vane passage 230, 234 for introducing hydraulic fluid under each of the vanes 208, so as to move the vanes 208 to the extended position when located in a dwell section 260. In order to prevent circulation of the fluid, solenoid valve 281 (V2) is armed (mechanically, piloted or electrically), hydraulic fluid is directed to passage 240, 262, valve 250 moves to a spring return position, hydraulic fluid is drained from under the vanes 208 and the vanes 208 are clamped within the slots 209 once the vanes 208 leave the dwell sections 260. When solenoid valve 281 (V2) is disarmed the spring offset condition returns the vanes 208 to the extended position under moderate pressure to prevent shock When the setting pressure of valve 250 is reached, then the valve 250 is reset to allow the main pump pressure to be directed under the vanes 208 when the main pump pressure exceeds the low pilot and clamping pressure. Pressure responsive shuttle valve 282 (V4) prevents loss of the under vane pressure. It will be appreciated that hydraulic pumps may not necessarily require hydraulic pressure to be applied under the vanes (or under the vane pins) because centrifugal force typically causes the vanes to extend when the retaining means are released.
A hydraulic circuit showing how the machine may be used as a motor is shown in
The rotor 206 has a passage 1710 formed therein. Passage 1710 can come into register with a source of pressurised pilot hydraulic fluid. Passage 1710 is in fluid communication with another passage 1706 that, in turn, is in fluid communication with another passage 1715. Plugs 1716 and 1717 close respective ends of passages 1706 and 1715.
Passage 1715 opens into chamber 1703. Passage 1705 opens into chamber 1704. Ball 1709 acts as a shuttle valve in a manner known to the person skilled in the art. In particular, if there is high pressure in passage 1705 and low pressure in orifice plug 1707, then ball 1709 is held against the seat of orifice 1707 as a check and fluid can move from chamber 1704 to chamber 1703.
If high pressure is applied to orifice 1707 via passage 1710 (such as would occur when it is desired to actuate the retaining means), the ball 1709 sits against the seat of gallery 1705 and pressure is applied to chamber 1703 to retain the vane in the retracted position (and potentially to drive the vane into the retracted position).
In the embodiment of
In normal operation when the retaining means are not operated, fluid flows from chamber 1704 to chamber 1703 through passages 1705 and 1706 to maintain hydraulic balance and ensure that the force on the top of the vane is not increased due to the larger base of vane, as is known in this art.
The embodiment shown in
An inner part of passage 302 is in fluid communication with a longitudinal passage 306 (best shown in
Passage 300 is plugged by plug 308 and passage 302 is plugged by plug 310.
When it is desired to retain the vanes in the retracted position, pressurised pilot hydraulic fluid is provided to passages 306, 302 and 300. The pressurised hydraulic fluid attempts to leave passage 300 and, in doing so, comes into contact with a sidewall of the vane 86. The pressurised pilot hydraulic fluid applies a force against the vane 86, normal to the face of the vane. As a result, the vane 86 is pressed against the opposed wall of the slot 84. This acts to retain the vane in the retracted position.
When the pressurised pilot hydraulic fluid is removed from passage 300, the hydraulic clamping force is removed and the vanes can again operate normally.
The embodiment shown in
In the embodiments shown in
As best shown in
An engagement pin 384 is positioned inside passageway 350. Passageway 350 comes into register with a slot that provides for fluid communication of pressurised pilot hydraulic fluid. A screw plug 352 having an opening therethrough is screwed into the end of passage 350 in order to retain the engagement pin 384 in passageway 350. A return spring 354 is mounted between the engagement pin 384 and a shoulder 356 formed near the end of passageway 350.
A further passage 358 having a check valve 360 and a screw in plug 362 is provided to enable hydraulic fluid to move from either the chamber at system pressure or underneath the vane 86 into the oil gallery 102 positioned under the under vane pins 340. This allows the oil gallery 102, which is located under the under vane pins and hence under the vanes, to always contain pressurised hydraulic fluid during use of the machine. The machine is preferably arranged such that a check valve is always positioned in fluid communication with the pressurised regions of the chamber during normal use. In this manner, system hydraulic pressure acts on pin 340 to provide appropriate pressure balance on the vane and to ensure that the vane remains in contact with the chamber wall whilst travelling along the rise regions. Other known arrangements, such as using annular grooves, may also be used to supply system hydraulic pressure to under the vane pins 340.
When the pressurised pilot hydraulic fluid is removed from passageway 350, the return spring 354 causes the engagement pin 348 to be moved out of engagement with the undervane pin 340. Thus, the vane 86 is then free to move to the extended position as the rotor passes into the rise regions.
The body of the rotor 60 is also provided with a first passage 380 and a second passage 382. An engagement pin 384 is positioned in first passage 380.
Engagement pin 384 is provided with a bore 386 that passes through the engagement pin 384. Bore 386 defines, at one end, a tapered recess 388 that engages with a complementary shaped tapered head on the engagement pin 384. As can be seen from
In order to retain the vanes 86 in the retracted position, pressurised pilot hydraulic fluid is supplied via passage 380. This forces the engagement pin 384 to move such that its tapered head fits into the tapered recess 388 on undervane pin 340. In order to disengage the engagement pin 384, the pressurised pilot hydraulic fluid flow to passage 380 is stopped and pressurised pilot hydraulic fluid then sent to passage 382. The pressurised hydraulic fluid travels along passage 382, through bore 386 and thereafter engages with the head of engagement pin 384. This causes engagement pin 384 to move out of the tapered recess 388. This then allows the vane 86 to move between the retracted and extended position. Travel of the pin 384 away from undervane pin 340 is limited by appropriate shaping of the passage 380. The shape of passage 380, together with the engagement pin 384, acts as a check valve to prevent flow of pressurised hydraulic fluid from passage 382 through all of passage 380.
As best shown in
When all of the vanes progressively move to the retracted position and are locked down when the hydraulic machine shown in
Passage 410 includes an enlarged portion 412. In this section a spool valve 414 is provided. Spool valve 414 includes a closed head 416, a passage 418 and another passage 420. Passage 420 is generally in alignment with passage 410. As can be seen from
A spool plug 422 closes the enlarged portion 412 of passage 410.
A further passage 424 is provided, which passage 424 can move into register with a source of pressurised pilot hydraulic fluid. Passage 424 is in fluid communication with passage 426. A plug 428 closes the outer end of passage 426. A further passage 430 extends from passage 426 and opens into the enlarged region 412 of passage 410. Passage 430 is closed by plug 431.
When no pressurised pilot hydraulic fluid is applied to passage 424, the spool valve adopts the position shown in
However, as the vanes are locked in the retracted position, the number of vanes moving into the retracted position progressively increases until all vanes are in the retracted position. It will be understood that this has the effect of reducing the combined volume of the undervane oil gallery 102 and the undervane passages (by virtue of the vanes moving down to reduce the volume of the undervane passages). Thus, it is necessary to vent some of the oil contained in the undervane passages.
When the vanes are to be moved into the retracted position, pressurised pilot hydraulic fluid is supplied to actuate the retaining means, which may be any of the retaining means described in this specification. At the same time, pressurised hydraulic fluid is supplied to passage 424. Due to the configuration of passages 424, 426 and 430, pressurised pilot hydraulic fluid impinges on the closed head 416 of spool valve 414 and forces the spool valve to move from the position shown in
When pressurised pilot hydraulic fluid is removed from passage 424, the spool valve 414 can move from to the position shown in
Undervane pin 340 includes a tapered recess 346 that is adapted to receive a complementary shaped tapered head on pin 600.
When it is desired to actuate the engagement pin 600 to retain the vanes 86 in the retracted position, pressurised pilot hydraulic fluid is supplied to passage 602, which forces engagement pin 606 to move into tapered recess-346 in undervane pin 340. At the same time, bore 608 in the engagement pin 600 comes into alignment with bore 610 formed in the rotor. Bore 610 has a plug 611 closing its outer end. In this fashion, pressurised fluid in undervane pin gallery 102 can be vented from the undervane pin gallery 102.
An engagement pin 348 is used to selectively retain the vane 86 in the retracted position. The engagement pin essentially operates along the same principle as the engagement pin of
The embodiment of
During extension of engagement pin 348, hydraulic fluid in chamber 704 that surrounds the tapered head of engagement pin 348 will become pressurised and require venting. To this end, a slot 706 is formed, which slot 706 extends from chamber 704 to slot 708 formed in rotor 60. Slot 706 is preferably formed by recessing the side of the vane pin 340. Alternatively, slot 706 may be formed in the side wall of the vane pin duct that houses the vane pin 340.
In the power steering pump 500 shown in
Outlet line 520 from main pump P1 has a flow orifice 524. As fluid flows along outlet line 520, it passes through flow orifice 524. Flow orifice 524 causes a pressure drop. The pressure in outlet line 520 measured before the orifice is designated by pressure PR10. The pressure in the outlet line after the flow orifice is designated by pressure PR8.
The control system for controlling the operation of the second pump P2 includes a spool valve 526. One end 528 of the spool valve detects pressure PR10. The other end 530 of spool valve 526 detects pressure PR8. Additionally, end 530 of spool valve 526 has a spring 532 mounted thereto. Spring 532 has a weight or strength that sets the pressure drop where the second pump cuts in.
In operation, as the flow through outlet 520 from the main pump P1 increases, for example by virtue of increasing engine revolutions of the motor vehicle, the pressure drop across restriction orifice 524 increases. When the pressure drop across orifice 524 increases to a level where pressure PR10 is greater than the combined pressure PR8 plus the force of spring 532, pressure PR10 in line 534 moves the spool valve 526 to the left against the biasing force of the spring 532. This then results in pressurised pilot hydraulic fluid being provided to the pressurised pilot hydraulic fluid gallery 534 of the second pump P2. This actuates the vane retaining means and the vanes on pump P2 become locked down in the retracted position. A non-return valve 536 is provided in the relevant fluid line.
If the flow through outlet 520 drops to a level where the pressure PR10 is less than the total of pressure PR8 plus the biasing force of spring 532 the spool valve 526 moves to the right. In this position, the pressurised pilot hydraulic fluid is no longer supplied to gallery 534 and the retraction means are thereby released. At the same time, pilot fluid travels via line 538 to the undervane passages 540. This assists or facilitates movement of the vanes from the retracted position to the extended position as the vanes move into rise regions inside the pump.
The flow circuit shown in
The flow circuit shown in
The flow and control circuit shown in
In order to demonstrate the benefits of the power steering pump shown in
In comparison, the power steering pump in accordance with the present invention can be operated such that the second pump P2 can effectively be switched off by retaining the vanes in the retracted position once engine speed gets above approximately 1200 rpm. The flow arising from this operation is shown in
power steering pump is running 1:1 relative to engine speed;
engine consumes 0.35 gallons per horse power hour;
6.6 lbs in 1 US gallon;
the pump will be running an average efficiency of 75%
rotors are 6 gallon primary ring and 5 gallon secondary ring
pressures and engine speed data referenced from Mack Truck consultant;
standard power steering pump (comparator) will pump 11 GPM at 1200 rpm running an average efficiency of 75%.
Results and Comparison
Shown in Table 1, the power steering pump in accordance with the present invention will provide an average saving of 2.2 horsepower (typical highway truck). This power saving will equate to approximately 120 US gallons per 1000 hours of operation for each truck it is fitted to. This is under the assumption that the pump in accordance with the present invention will be replacing a positive displacement pump running 11 GPM at 1200 rpm.
Case Study (National per 4000 Hours)
7 million trucks running in North America, each truck running approximately 4000 hours per year (average). If the pump power steering pump in accordance with the present invention is fitted to only 25% of these trucks, the annual fuel saving would be 840 million gallons of fuel per annum.
Case Study (per Vehicle per 4000 Hours)
USA based on the fuel saving figures will be $480.
Australia based on the fuel saving figures will be $1080.
Europe based on the fuel saving figures will be $2000.
Each of the vanes 1151 includes a cavity or hole 1152 formed in a side wall thereof. Each clamping mechanism comprises two small balls 1153, 1154 that are in engagement with a spool 1155. Spool 1155 will be described in greater detail with reference to
As seen in
When the pump 1170 is operating normally and the vanes 1151 are unclamped (or not retained), the spools 1155 are retracted, meaning that there is no force applied to the balls 1153, 1154. In the retracted position, ball 1153 rests within the spool region 1161 of smaller diameter. This provides sufficient clearance such that ball 1154 is not pushed into contact with the side of the vanes 1151 by way of intermediate ball 1153.
When the pump is clamped (i.e. when the vanes are retained in the retracted position), as shown in
Spool 1196 has substantially the same shape as spool 1155. Spool 1196 is in fluid communication with pressurised oil via galleries 1197. Each spool 1196 is slidably mounted in a gallery 1198 in the rotor 1191 together with a spring. An under vane passage extends beneath each vane 1192.
When the pump 1190 is operating normally and the vanes 1192 are unclamped, the spools 1196 are retracted, meaning that there is no force applied to the balls 1195. In the retracted position, ball 1195 rests within the spool 1196 region of smaller diameter. When the pump 1190 is clamped, a positive pressure signal comes from the pressure plate via galleries 1197. This acts on the spools 1196 and causes the spool 1196 to compress the spring and to laterally force the ball 1195 into the cavity 1193 formed in the side of the vane 1192, to thereby retain the vane 1192 in the retracted position. In the absence of a positive pressure signal, the spring moves the spool 1196 region of relatively smaller diameter back into engagement with the ball 1195.
The first rotor part 1400 also includes a central opening 1406 that is splined and which receives a splined shaft (not shown) in the completed hydraulic machine.
First rotor part 1400 includes a plurality of vane retaining means movement passages. In particular, the vane retaining means movement passages comprise spool movement passages 1408, 1410 (the other spool movement passages are not numbered for the sake of clarity). First rotor part 1400 also includes dowel holes 1412 and 1414. The first rotor part 1400 also includes a plurality of oil galleries, some of which are numbered at 1416. Oil galleries 1416 receive pressurised oil and provide pressurised oil to the spools to selectively actuate the spools. Galleries 1416 may be formed by cross drilling to the centre of the spline cavity 1406. The outermost portion of gallery 1416 is then plugged. Pressurised oil can be provided through the shaft extending through the spline cavity, into the spline chamber 1406 and then into gallery 1416 to thereby supply pressurised oil to the spool cavity 1410 to move the spool.
Second rotor part 1420 also includes dowel holes 1428, 1430. These are dowel holes are formed such that they can be placed in alignment with dowel holes 1412, 1414 in the first rotor part 1400.
The second rotor part 1420 includes oil galleries 1436, 1438 that provide fluid communication from the undervane passages 1440 to the external periphery of the rotor part 1420. In this manner, the undervane passages have equal pressure to the region of the pump through which the vane is travelling.
As can also be seen from
In order to assemble the final rotor, spools 1460 and balls 1462 (see zure 54) are positioned in the vane retaining means movement passages and the vanes are positioned in the vane slots. The rotor parts are dowelled together and spot welds are applied on the interface of the two rotor parts to thereby form the completed rotor.
As can be seen from
By forming the rotor from two rotor parts, it is possible to minimise the amount of machining required to form the rotor. This assist in ensuring that the rotor is as strong as it can possibly be, it being appreciated that excess machining of the rotor will remove metal from the rotor and thereby weaken the rotor. Further, the amount of plugging of drill holes used to form the oil galleries is minimised, thereby enhancing the speed of manufacture. By forming the rotor from two rotor parts, a rotor of small dimension that carries a large number of vanes, such as from 10 to 12 vanes, can be formed. These rotors are robust. Furthermore, it will be understood that when the spools move in a generally longitudinal direction, this causes the balls to move in a direction that is generally lateral to the spools. Accordingly, the vane retaining means is of compact dimension.
Other advantages arising from the method of making the motor include:
Importantly the tolerances in such systems with a small number of vanes (such as 3 or 4 vanes) are much greater and relatively large ball bearings for detent and retaining of the vanes can be loosely positioned in slots in vane systems that pump or compress gases. The outlet pressures of hydraulic pumps tend to be 25 to 40 times higher than the outlet pressures of gas pumping systems.
The present invention provides a hydraulic machine that can be operated in an economical mode in situations where conventional hydraulic machines would be consuming unnecessary power. The hydraulic machine of the present invention can be manufactured using existing manufacturing facilities. The hydraulic machine of the present invention allows for selectively retaining the vanes in the retracted position. The retaining means most suitably interact with the vanes when the vanes are in the retracted position to maintain the vanes in the retracted position. The retaining means are capable of retaining the vanes in the retracted position even as the vanes pass through the rise regions, the major dwell regions and the fall regions. Most suitably, the retaining means interact with the vanes as hydraulic fluid passages that operate the retaining means associated with each vane each come into fluid communication with a source of pressurised hydraulic fluid. The retaining means may be selectively actuable by an operator of the hydraulic machine or by an automatic control means that responds to situations where low flow or low power is required. Preferred embodiments of the machine also allow for positive driving of the vanes from the retracted position to the extended position in the dwell regions by virtue of applying pressurised hydraulic fluid to the undervane passages.
For start-up, known hydraulic vane motors typically require an external force to extend the vanes. Springs are normally used for initial start-up and then system pressure is directed under the vanes to maintain pressure equilibrium. In the present invention, however, the remote pilot fluid extends the vanes and eliminates the need for springs.
In this way, the hydraulic machine of the present invention may be operated such that hydraulic fluid is not pumped excessively or unnecessarily, in the absence of expensive space invasive clutches or other disconnecting means.
The hydraulic pump or motor is suitable for use in, for example, earth moving, industrial and agricultural machines, waste collection vehicles, fishing trawlers, cranes, and vehicle power steering systems, as well as in air compressors and air-conditioners.
Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It is to be understood that the invention encompasses all variations and modifications that fall within its spirit and scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003903625 | Jul 2003 | AU | national |
| 2005902406 | May 2005 | AU | national |
This application is a continuation of application Ser. No. 12/466,280 filed May 14, 2009, which is (a) a continuation-in-part of application Ser. No. 11/914,203 filed Jul. 1, 2008, which is a 371 filing of International Patent Application PCT/AU2006/000623 filed May 12, 2006, and (b) a continuation-in-part of application Ser. No. 11/331,356 filed Jan. 13, 2006, which is a continuation of International Patent Application PCT/AU2004/000951 filed Jul. 15, 2004. The entire content of each earlier filed application is expressly incorporated herein by reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20140328709 A1 | Nov 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12466280 | May 2009 | US |
| Child | 14095654 | US | |
| Parent | PCT/AU2004/000951 | Jul 2004 | US |
| Child | 11331356 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11914203 | US | |
| Child | 12466280 | US | |
| Parent | 11331356 | Jan 2006 | US |
| Child | 12466280 | US |
