Piston pump

Abstract

A hand-operated piston pump includes a drive shaft and a rotor mounted in a housing case, the rotor having axial compression chambers, a piston biased by an elastic member sliding in each compression chamber and having a projecting end that engages a cam track; a fluid reservoir in the housing case; a valve plate downstream of the rotor having conduits for a pressurized fluid that communicate with conduits in walls of the compression chambers, the valve plate being non-rotatably mounted below the housing case and communicating with conduits that carry the pressurized fluid to and from a consuming unit through an interposed check valve inserted in a corresponding valve body, the valve body having an upper flange with fluid supply and return channels communicating with the fluid conduits of the valve plate. The valve plate floats relative to the upper flange and is separated therefrom by a separating member.

Claims

1. A hand-operated piston pump, particularly for directional control of watercrafts, or boats, said pump comprising: a drive shaft (3), which is rotatably mounted in a housing case (1); a rotor (4), which is mounted in the housing case (1) and is rotationally integral with the drive shaft (3), said rotor (4) having a plurality of axial compression chambers (104) formed in a body of said rotor (4), said axial compression chambers (104) surrounding the drive shaft (3); a piston (304) axially and slidably housed in each compression chamber (104) and biased by an elastic member, the piston having one end projecting out of one end side of a corresponding compression chamber (104) against a cam track (8) comprising an annular plate inclined with respect to an axis of rotation of the rotor (4); a fluid reservoir in said housing case (1); and a valve plate (6) located downstream from the rotor (4) and having at least two separate fluid passage conduits (106, 306) for passage of a pressurized fluid, the at least two separate conduits (106, 306) alternately communicating with conduits (204) for drawing or discharging the pressurized fluid, the latter conduits being provided in bottom delimiting walls of the compression chambers (104) facing toward the valve plate (6), wherein the valve plate (6) is non-rotatably mounted below the housing case (1) and communicates with conduits for supplying and returning the pressurized fluid to a consuming unit through an interposed check valve (28) inserted in a corresponding valve body (27), said valve body (27) having an upper flange (271), said upper flange having fluid supply and return channels communicating with said fluid passage conduits (106, 306) of said valve plate, and wherein said valve plate (6) is disposed to float relative to said upper flange (271), sealing members being interposed between said valve plate (6) and said upper flange (271) to cause said valve plate (6) to be separate from said upper flange (271).

2. The hand-operated piston pump as claimed in claim 1, further comprising a locking ring, which is fixed to said upper flange (271), said valve plate (6) being interposed between said locking ring and said upper flange (271), such that said locking ring presses said sealing members, wherein said valve plate is mounted to be in contact with said locking ring and separate from said upper flange (271).

3. The hand-operated piston pump as claimed in claim 1, wherein said sealing members are O-rings having a lobe shape, and wherein said sealing members are disposed in corresponding lobe-shaped seats formed in one or both of a thickness of said valve plate (6) or a thickness of said upper flange (271).

4. The hand-operated piston pump as claimed in claim 3, wherein two seals are provided within two corresponding seats, said seats communicating with said fluid passage conduits (106, 306) in said valve plate (6) and with said fluid supply and return channels in said upper flange (271).

5. The hand-operated piston pump as claimed in claim 1, wherein said drive shaft (3) is disengaged from said rotor (4), an engagement member being provided on said drive shaft (3), said engagement member engaging a corresponding engagement seat on said rotor (4), said engagement member (31) having an element that radially extends from a lateral surface of said drive shaft (3), said engagement seat (41) being shaped as a recess formed in a thickness of a lateral wall of said rotor (4), such that one or both of said drive shaft (3) or said rotor (4) are free to translate along their longitudinal axes, and wherein an elastic member is provided that is shaped as a helical spring disposed coaxially with said drive shaft (3) and interposed between said rotor (4) and said housing case (1).

6. The hand-operated piston pump as claimed in claim 1, wherein at least one relief valve is provided, said relief valve being inserted in a seat formed in a thickness of said valve body (27), and wherein said relief valve is configured to allow fluid passage to the reservoir when a given threshold pressure is reached in delivery or suction ports of said pump.

7. The hand-operated piston pump as claimed in claim 1, wherein the drive shaft (3) has a longitudinal channel extending over at least part of a length of the drive shaft, the longitudinal channel being connected to a radial cannel that communicates with the reservoir.

8. The hand-operated piston pump as claimed in claim 7, wherein said longitudinal channel is defined by a longitudinal hole formed at a center axis of said shaft, said longitudinal hole being threaded at least over a part of its length, at an end of said drive shaft (3) toward said valve plate (6).

9. A steering device for vehicles, particularly boats or the like, comprising: a manual control member (11) connected to a drive shaft (3) of a pressurized fluid supply and distribution unit and configured to manually drive the pressurized fluid supply and distribution unit during rotation of the drive shaft (3), the supply and distribution unit comprising a piston pump, wherein said piston pump is connected by delivery and suction ports respectively and alternately to two chambers of at least one steering actuator through hydraulic conduits for alternately supplying fluid to either one of the two chambers of the at least one steering actuator, according to a direction of movement of the manual control member, and wherein said piston pump is according to claim 1.

10. The steering device as claimed in claim 9, wherein the steering actuator is a double-acting hydraulic cylinder.

11. The steering device as claimed in claim 9, wherein said piston pump further comprises a locking ring, which is fixed to said upper flange (271), said valve plate (6) being interposed between said locking ring and said upper flange (271), such that said locking ring presses said seals, and wherein said valve plate is mounted to be in contact with said locking ring and separate from said upper flange (271).

12. A hand-operated piston pump, particularly for directional control of watercrafts or boats, said pump comprising: a drive shaft (3), which is rotatably mounted in a housing case (1); a rotor (4), which is mounted in the housing case (1) and is rotationally integral with the drive shaft (3), said rotor (4) having a plurality of axial compression chambers (104) formed in a body of said rotor (4), said axial compression chambers (104) surrounding the drive shaft (3); a piston (304) axially and slidably housed in each compression chamber (104) and biased by an elastic member, the piston having one end projecting out of one end side of a corresponding compression chamber (104) against a cam track (8) consisting of an annular plate inclined with respect to an axis of rotation of the rotor (4); a fluid reservoir in said housing case (1); a valve plate (6) located downstream from said rotor (4) and having at least two separate fluid passage conduits (106, 306) for passage of pressurized fluid, the at least two separate conduits (106, 306) alternately communicating with conduits (204) for drawing or discharging said pressurized fluid, the latter conduits being provided in bottom delimiting walls of said compression chambers (104) facing toward said valve plate (6), wherein said valve plate (6) is non-rotatably mounted below said housing case (1), and said valve plate (6) communicating with conduits for supplying and returning the pressurized fluid to a consuming unit through an interposed check valve (28) inserted in a corresponding valve body (27), said valve body (27) having an upper flange (271), said upper flange having fluid supply and return channels communicating with said fluid passage conduits (106, 306) of said valve plate, wherein said drive shaft (3) is disengaged from said rotor (4), wherein an engagement member is provided on said drive shaft (3), said engagement member engaging with a corresponding engagement seat on said rotor (4), and wherein said engagement member comprises an element that radially extends from a lateral surface of said drive shaft (3) and said engagement seat is defined by a recess formed in a thickness of a lateral wall of said rotor (4), such that one or both of said drive shaft (3) or said rotor (4) are free to translate along their own longitudinal axes; and a helical spring coaxial with said drive shaft (3) and interposed between said rotor (4) and said housing case (1), wherein said valve plate (6) is disposed to float relative to said upper flange (271), sealing members being interposed between said valve plate (6) and said upper flange (271) to cause said valve plate (6) to be separate from said upper flange (271).

13. The hand-operated piston pump as claimed in claim 12, further comprising a locking ring, which is fixed to said upper flange (271), said valve plate (6) being interposed between said locking ring and said upper flange (271), such that said locking ring presses said sealing members, wherein said valve plate is mounted to be in contact with said locking ring and separate from said upper flange (271).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features and advantages of the present invention will appear more clearly from the following description of a few embodiments, illustrated in the enclosed drawings, in which:

(2) FIGS. 1a-1d show four sections of a pump according to the present invention as viewed along four different sectional planes;

(3) FIGS. 2a and 2b show two different views of the valve plate in a piston pump according to the present invention.

(4) It should be noted that, while the figures enclosed herein illustrate a preferred embodiment of a pump according to the present invention, those figures shall be only intended as an exemplary illustration for a better understanding of the concepts and advantages of the present invention.

(5) Thus, those figures shall not be intended to limit the scope and breadth of the present invention, in particular, the provision of a pump having floating parts.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(6) FIGS. 1a-1d show a hand-operated piston pump according to the present invention, which is particularly suited for directional control of a watercraft, a boat or the like.

(7) The illustrated pump comprises a drive shaft 3, which is rotatably mounted in a housing case 1, a rotor 4 being mounted in the housing case 1.

(8) The rotor 4 is rotationally integral with the drive shaft 3 and has a plurality of axial compression chambers 104 formed in the body of the rotor 4, which surround the drive shaft 3.

(9) A piston 304 is axially and slidably housed in each compression chamber 104 and is biased by elastic means 305, with one end projecting out of one end side of the corresponding compression chamber 104 against a cam track 8 consisting of an annular plate inclined with respect to the axis of rotation of the rotor 4.

(10) The pump further comprises a fluid reservoir 11 in the housing case 1, as well as a valve plate 6 located downstream from the rotor 4.

(11) The valve plate 6 has at least two separate conduits 106, 306, see FIGS. 2a and 2b, for the passage of pressurized fluid, which alternately communicate with conduits 204 for drawing/discharging the pressurized fluid, the latter conduits being provided in the bottom delimiting walls of the compression chambers 104 facing toward the valve plate 6.

(12) Furthermore, the valve plate 6 is non-rotatably mounted below the housing case 1 and communicates with the conduits for supplying and returning the pressurized fluid to a consuming unit through an interposed check valve 28 inserted in a corresponding valve body 27, the latter having an upper flange 271, with fluid supply and return channels communicating with the fluid passage conduits 106, 306 of the valve plate 6.

(13) It shall be noted that while the check valve may be fabricated as is known in the art, in the present embodiment it is fabricated according to the characteristics described in EP 1382845.

(14) The use of the check valve prevents fluid from being supplied and discharged to the chambers of the steering actuator when the control member is still, and also affords a more efficient adjustment of supply thereto during steering.

(15) Particularly, the valve plate 6 is mounted to float relative to the upper flange 271.

(16) O-ring seals or the like 61 are interposed between the valve plate 6 and the upper flange 271 such that the valve plate 6 is separate from the upper flange 271.

(17) Therefore, the valve plate 6 is an independent part, which is non-rotatably mounted below the housing case 1 and above the upper flange 271.

(18) Preferably, the upper flange 271 has at least two engagement teeth, not shown, which cooperate with corresponding engagement seats on the valve plate 6 to prevent any rotation of the plate.

(19) Particularly referring to FIG. 1a, O-ring seals 121 may be also provided at the interface between the housing case 1 and the upper flange 271.

(20) Also preferably, the valve body 27 and the upper flange 271 are made of one piece.

(21) According to the variant embodiment of the figures, a locking ring 7 is provided, which is fixed to the upper flange 271.

(22) The valve plate 6 is interposed between the locking ring 7 and the upper flange 271, such that the locking ring 7 may press against the seals 61 and the valve plate 6 is mounted in contact with the locking ring 7 and separate from the upper flange 271.

(23) FIG. 2b shows a section of the valve plate 6 and the locking ring 7 assembled together, as taken along a longitudinal plane.

(24) In the variant of FIG. 2b, the section of the valve plate 6 has a L-shaped profile, whereas the locking ring 7 has a section with an inverted L-shaped profile.

(25) This configuration optimizes the sealing action of the locking ring 7 toward the valve plate 6 while limiting the thickness of the pump and optimizing its size.

(26) As shown in FIG. 2a, the seals 61 are O-rings, said O-rings having a lobe shape.

(27) Particularly, the seals are accommodated in corresponding lobe-shaped seats 62.

(28) Particularly referring to FIG. 2a, the seats 62 may be formed in the thickness of the valve plate 6.

(29) In one embodiment, these seats 62 may be formed in the thickness of the upper flange 271.

(30) Preferably, according to the illustrated variant embodiment, two seals 61 are provided within two corresponding seats 62, which communicate with the fluid passage conduits 106, 306 formed in the valve plate 6 and with the fluid supply and return channels formed in the upper flange 271.

(31) Particularly, the fluid passage conduits 106, 306 are placed at the center of each seat 62 and form a tank element which is filled with the fluid during operation of the pump.

(32) Referring to FIG. 1b, the drive shaft 3 is disengaged from the rotor 4, an engagement member 31 being provided on the drive shaft 3 and engaging with a corresponding engagement seat 41 on the rotor 4.

(33) The engagement member 31 preferably consists of an element that radially extends from the lateral surface of the drive shaft 3, the engagement seat 41 consisting of a recess formed in the thickness of the lateral wall of the rotor 4, such that the drive shaft 3 and/or the rotor 4 are free to translate along their own longitudinal axis.

(34) Preferably, the engagement member 31 is not formed of one piece with the drive shaft 3 but consists of a pin 31 which is housed in a receptacle formed in the drive shaft 31, engaging with the engagement seat 41.

(35) In order to allow longitudinal translation of the drive shaft 3 and the rotor 4, the pin 31 is suspended, i.e. does not rest on the bottom of the engagement seat 41 formed in the rotor 4.

(36) Elastic elements may be provided in the engagement seat 41, for damping the movement of the pin, such that the pin is not allowed to contact the bottom of the engagement seat 41.

(37) A helical spring 32 is also provided coaxial with the drive shaft 3 and interposed between the rotor 4 and the housing case 1.

(38) The helical spring 32 allows adjustment of the relative movement of the drive shaft 3-rotor 4 assembly, especially during mounting of the individual parts, as well as during oil purging.

(39) During pump assembly, the helical spring 32 may become compressed to a given extent.

(40) In this configuration, when the housing case 1 is mounted, the pin 31 moves downwards, and remains suspended at about the middle the engagement seat 41.

(41) Depending on the pre-loading of the helical spring 32, this spring 32 pushes the drive shaft 3 upward and the rotor 4 downward, while still maintaining the sealing effect, because the housing case 1 stops the movement of the drive shaft 3 upward.

(42) For the force of the helical spring 32 to be properly discharged between the housing case 1 and the rotor 4, the engagement seat 41 for the pin 31 has a depth that is much greater than its diameter and/or its section.

(43) FIG. 1d depicts a section of a pump according to the present invention in one embodiment, in which at least one, preferably two relief valves 9 are inserted in a seat formed in the thickness of the valve body 27.

(44) The relief valves allow the passage of fluid to the reservoir 11 when a given threshold pressure is reached in the delivery 12 and/or suction 13 ports of the pump.

(45) Particularly referring to FIGS. 1a-1d, the fluid passes from the drawing/discharging conduits 204 in the bottom delimiting walls of the compression chambers 104 to the delivery 12 and/or suction 14 ports through the fluid passage conduits 106, 306 of the valve plate 6 and through the check valve 28.

(46) Particularly, the conduits 106, 306 communicate with the check valve 28 through two holes 279 in the upper flange 271.

(47) If high pressure is reached in the delivery 12 and/or suction 13 ports, the relief valves 90 allow venting of the fluid into the reservoir 11.

(48) As shown in FIG. 1d, the relief valves may be located in bodies with cylindrical symmetry, such as cans, inserted in the thickness of the wall of the valve body 27.

(49) These cans allow the provision of self-standing relief valves, which may be inserted from the back of the pump, i.e. the bottom, irrespective of the construction of the valve body 27.

(50) Like the relief valves, the intake valves may be also inserted in a seat formed in the thickness of the valve body 27.

(51) The intake valves may be located in bodies with cylindrical symmetry, such as cans, inserted in the thickness of the wall of the valve body 27.

(52) Several vents may be provided in the various parts, for venting excess fluid, according to navigation conditions. As the drive shaft 3 is rotated, the piston 7 may push on an area filled with fluid, and that fluid should be vented to restore a normal drive feel.

(53) Therefore, apertures may be preferably provided, for example on the valve plate 6, for the passage of excess fluid.

(54) The drive shaft 3 may also have fluid venting channels, for re-introducing excess fluid into the reservoir 11.

(55) These channels may be formed externally, i.e. on the outer surface of the drive shaft 3 or, like in the embodiment shown in FIG. 1a, the drive shaft 3 may have a longitudinal hole 33 formed therein over at least part of its length and connected to a radial hole 34 in communication with the reservoir 11.

(56) Preferably, the longitudinal hole 33 is threaded at least over a part of its length, at the end of the drive shaft 3 facing toward the valve plate 6.

(57) While the invention has been described in connection with the above described embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the scope of the invention. Further, the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and the scope of the present invention is limited only by the appended claims.