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(11) | EP 1 371 849 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Detachable heads for hydraulic pumps and motors |
| (57) Detachable heads for hydraulic motors and pumps of the type comprising a body (4),
which contains a protruding shaft (7) and a shaft (10) arranged inside said body,
said shafts being mutually engaged by way of gears (8, 9), two bushes, a cover and
a base, characterized in that on the faces that are directed toward the body of the
base (3) and of the cover (2) there are respective networks of interconnected slots
(22) that are adapted to accommodate respective deformable gaskets (23) made of a
material such as rubber, in that an open cavity for the protruding shaft (7) is provided
in said base, and in that oil draining means (26) are present in said cover (2). |
[0002] Conventional gear-based motors and pumps comprise a body that is comprised between two heads, which contains an internal shaft and a protruding shaft, which are parallel and have respective meshing gears keyed thereon; such pumps and motors are manufactured so that the direction of rotation of the shaft is determined during assembly according to the requirements of the final user.
[0003] In practice, the manufacture of a hydraulic machine of the described type forces the manufacturer to use different components according to the intended type of use: a pump can in fact be right-handed or left-handed or also reversible; likewise, a motor can assume the same three configurations, which depend in this case on the flow of the oil.
[0004] In order to reduce to a minimum the components that differ according to the end use, manufacturers have evolved in the manufacture of pumps and motors in which a sophisticated ball-valve system, arranged within a sealing bush that is suitably contoured so as to ensure tightness against overpressures on both of its surfaces, allows, by using a few different parts with respect to standard models, to make a same machine suitable to rotate in the two directions.
[0005] The choice currently shared by most manufacturers is to make the components required for bidirectionality of the machine reside within the body of the machine.
[0006] This solution is disadvantageous if it is necessary to act on those elements to change the type of operation according to new requirements that have arisen (in the few cases in which this is actually possible): it is in fact necessary to disassemble the machine completely and to eliminate the fixings provided in order to ensure the positioning of the ball valve. Rarely can the user convert a machine purchased with certain characteristics into a machine having different characteristics.
[0007] The arrangement of the components required for bidirectionality inside the body also makes it less accessible for a scarcely specialized operator to perform the operations for disassembly, modification and subsequent reassembly of the machine.
[0008] The aim of the present invention is to obviate the cited shortcomings and to meet the mentioned needs by providing detachable heads for hydraulic pumps and motors in which it is easy to perform the modifications required to change the operating characteristics.
[0009] Within this aim, an object of the present invention is to provide a line of machines, pumps and motors that have the greatest number of common parts and differ only for some constructive details of some of their parts.
[0010] Another object of the present invention is to provide a structure that is simple, relatively easy to provide in practice, safe in use, effective in operation, and relatively low in cost.
[0011] This aim and these objects are achieved by the present detachable heads for hydraulic motors and pumps comprising a body, which contains a protruding shaft and a shaft arranged inside said body, said shafts being mutually engaged by way of gears, a cover and a base, characterized in that on the faces of the base and of the cover that are directed toward the body there are respective networks of interconnected slots that are adapted to accommodate respective deformable gaskets made of a material such as rubber, in that an open cavity for the protruding shaft is provided in said base, and in that oil draining means are present in said cover.
[0012] Further features will become better apparent from the detailed description of a preferred but not exclusive embodiment of detachable heads for hydraulic motors and pumps, according to the invention, illustrated by way of non-limitative example in the accompanying drawings, wherein:
Figure 1 is a sectional view, taken along two perpendicular planes, of a machine on which the heads according to the invention are fitted;
Figure 2 is a sectional side view, taken along a substantially central plane, of a machine on which the heads according to the invention are fitted;
Figure 3 is a side view of a machine on which the heads according to the invention are fitted;
Figure 4 is a sectional view, taken along the line IV-IV of Figure 3, of a machine on which the heads according to the invention are fitted;
Figure 5 is a plan view of the cover according to the invention for the embodiment with internal recovery;
Figure 6 is a sectional view, taken along the line VI-VI of Figure 5, for the internal-recovery embodiment;
Figure 7 is a sectional view, taken along the line VII-VII of Figure 5, for the internal-recovery embodiment;
Figure 8 is a set of perspective views of the cover for the internal-recovery embodiment;
Figure 9 is a plan view of the cover according to the invention for the embodiment suitable both for external draining and for internal recovery;
Figure 10 is a sectional view, taken along the line X-X of Figure 9, for the embodiment suitable both for external draining and for internal recovery;
Figure 11 is a sectional view, taken along the line XI-XI of Figure 9, for the embodiment suitable both for external draining and for internal recovery;
Figure 12 is a perspective view of the cover, provided with the accessories for the embodiment suitable both for external draining and for internal recovery;
Figure 13 is a set of perspective views of the cover for the embodiment suitable both for external draining and for internal recovery;
Figure 14 is a plan view of the cover according to the invention for the internal-recovery embodiment with ball valve;
Figure 15 is a sectional view, taken along the line XV-XV of Figure 14, for the internal-recover embodiment with ball valve;
Figure 16 is a sectional view, taken along the line XVI-XVI of Figure 14, for the internal-recovery embodiment with ball valve;
Figure 17 is a set of perspective views of the cover for the internal-recovery embodiment with ball valve;
Figures 18, 19, 20 and 21 are views of the cycle of operations required to change the direction of rotation in machines that use the heads according to the invention.
[0013] With reference to the figures, the reference numeral 1 generally designates a machine provided with the detachable heads for hydraulic motors and pumps according to the invention. The detachable heads are constituted by the cover 2 and by the base 3, which are retained rigidly against the ends of the body 4 by the bolts with locking nuts 5.
[0014] Through a hole 6 provided in the base 3, the protruding shaft 7 extends into the internal compartment 4a of the body 4, where the gear 8, keyed on the protruding shaft 7, meshes with the gear 9 keyed onto the internal shaft 10. The body 4 has, on its two opposite faces, two access ducts 11 for the inflow and outflow of the oil with respect to the compartment 4a; the duct in which the oil is present at high pressure is the one designated by the reference numeral 11a, i.e., the duct having the smallest cross-section, while the duct in which the oil is present at low pressure is designated by the reference numeral 11b and has a larger cross-section.
[0015] The two shafts 7 and 9 are kept mutually in position by way of the end bushes 12, which are substantially shaped like a figure-of eight so as to accommodate, in each one of the two cavities provided, one of the two shafts 7 and 9 while still allowing it to rotate about its own axis. The axial distance between the two bushes, when the machine 1 is completely assembled, is slightly greater than the width of the gears 8 and 10, so as to allow their rotations.
[0016] The through hole 6 of the base 3 has an inner region 13, whose diameter approximates the diameter of the shaft 7 and is adapted to keep it in position, and an outer region 14, which has a larger diameter and is adapted to accommodate a sealing ring-bearing 15 that is adapted to prevent oil leakage.
[0017] A channel 16 connects the region 14 of the hole 6 to the blind cavity 17 that accommodates the end of the internal shaft 9. The channel 16 acts as a path for the oil, which once it reaches the barrier constituted by the bearing-ring 15, crosses said path and reaches the other end of the machine 1, in the cover 2, flowing in the axial channel 18 provided in the shaft 9.
[0018] The cover 2 has two cavities, designated by the reference numerals 19 and 20, which are similar to the cavity 17 of the base 3 in terms of dimensions and are connected each other by means of a duct 21; the portions of the cavities 19 and 20 that face the area where the duct 21 is provided have two recesses, designated by the reference numerals 19a and 20a respectively, in order to facilitate the outflow of the oil.
[0019] Seen in plan view, the cover 2 and the base 3 have networks of interconnected slots 22 (far shallower than the cavities 17, 19 and 20), which accommodate particular gaskets 23, which are shaped so as to fill the cavities that constitute the network 22 so as to retain a small perimetric portion of their contour that protrudes and ensures tightness when the cover 2 and the base 3 are fastened against the body 4. The gasket 23 forms two complementary cavities 24 and 25 that are contoured like a circular sector with an obtuse center angle; during operation, one of such cavities is at high pressure and the other one is at low pressure.
[0020] In order to allow the oil to drain, the cover 2 can have, in one of the two complementary cavities 24 or 25, an opening 26 that is connected to the bottom of the duct 21 for connecting the cavities 19 and 20.
[0021] The opening 26, if not used for internal draining of the oil, can be closed by means of a plug 27; in this case, the opening 26 must be provided with a thread 26a.
[0022] As an alternative, draining can be achieved by means of a channel 28 on the outer wall of the cover 2 that interferes with the cavity 19 and is a through channel along part of its extension; the oil can flow outside the machine 9 through the channel 28. The channel 28 also can be threaded; in this case, it becomes suitable for accommodating a threaded plug 29 with an O-ring for closing said draining channel 28.
[0023] Operation of the invention is as follows: when the machine 1 is used as a pump, the shaft 7 is driven externally by any power source; the oil that reaches the pump 1 from the low-pressure duct 11b reaches the mutually meshing gears 8 and 10. The direction of rotation of the shaft 7 is such that the gears push the oil into the high-pressure duct 1 1a. Axially, the oil cannot exit from the pump 1 along the shaft 7 due to the presence of the bearing and sealing ring, which prevents oil leakage, generally designated by the reference numeral 15. The oil that flows toward the base along the shaft 7 flows back to the cover along the channel 16, which connects the region 14 of the hole 6 with the cavity 17, and the axial channel 18, which is present in the shaft 9.
[0024] The oil can be drained according to two different principles: draining with internal recovery and external draining.
[0025] In draining with internal recovery, the opening 26 connects the complementary cavity 24, located in the oil inlet region, to the duct 21, allowing the oil to follow a path at the end of which it is again at the inlet 11, thus allowing to resume the working cycle.
[0026] In external draining, the opening 26, if provided, is closed by the plug 27 and the oil to be drained can flow freely outward through the channel 28.
[0027] A third embodiment, which uses particular bushes 12 provided with ball valves, allows to provide internal-recovery draining with the opening 26 closed by the plug 27 and the channel 28 closed by the threaded plug 29 with O-ring.
[0028] The constructive architecture of the machine 1 is such that the direction of rotation can be changed simply by following the operations shown in sequence in Figure 6. Starting for example with a right-handed unidirectional pump, it is necessary to unscrew the screws 5, remove the base 3 and extract one of the two bushes 12 and the pair of shafts 7 and 9. Once the two shafts have been swapped, the pump 1 can be reassembled with the reverse process. The apparatus obtained with the described operations is a left-handed unidirectional pump.
[0030] The seats for the balancing and containment gaskets are provided in the bases and in the cover, and therefore only these parts determine the direction of rotation and the type of product; all the other components, bushes, gear pair and body, are unified.
[0031] The sealing rings fitted on the shafts cannot withstand high pressures and therefore the underlying chamber must be connected to low-pressure areas (at most 2 or 3 bar for pumps and 10-15 bar for motors).
[0032] The higher pressure that must be withstood by the sealing ring for a motor, with respect to the sealing ring for a pump, is due only to the use of a special contoured steel washer that supports the sealing lip.
[0034] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.
[0036] In practice, the materials used, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claims.
[0037] The disclosures in Italian Patent Application No. BO2002A00038 from which this application claims priority are incorporated herein by reference.
[0038] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.
1. Detachable heads for hydraulic motors and pumps of the type comprising a body (4),
which contains a protruding shaft (7) and a shaft (10) arranged inside said body,
said shafts being mutually engaged by way of gears (8, 9), a cover (2) and a base
(3), characterized in that on the faces of the base (3) and of the cover (2) that are directed toward the body
(4) there are respective networks of interconnected slots (22) that are adapted to
accommodate respective deformable gaskets (23) made of a material such as rubber,
in that an open cavity (6) for the protruding shaft is provided in said base (3), and in that oil draining means (26) are present in said cover (2).
2. The heads according to claim 1, characterized in that said cover (2) has two blind cavities (19, 20), which are adapted to accommodate
rotatably the ends of the internal shaft (10) and of the protruding shaft (7), and
in that said base (3) has a blind cavity (17) for accommodating the other end of the internal
shaft (10) and an open cavity (6) for accommodating the protruding shaft (7), said
internal shaft (10) and said protruding shaft (7) being parallel and having respective
meshing gears (9, 8) which are keyed thereto.
3. The heads according to claim 1, characterized in that said blind cavities (19, 20) are deeper than the slots that constitute said network
(22).
4. The heads according to claim 1, characterized in that said network of slots (22) of the base (3) and of the covers (2) comprises cavities
for rotatably supporting said shafts (17, 19, 20), which are extended with facing
peripheral recesses, a slot that is external to the two and is substantially shaped
like a figure-of-eight with two mutually separated connecting portions, and a diamond-shaped
perimetric slot with rounded corners which is connected to the figure-of-eight slot
by means of short portions.
5. The heads according to claim 4, characterized in that said network (22) is symmetrical with respect to a plane that passes through the
rotation axes of the two shafts (7, 10) and with respect to a plane that is perpendicular
to the preceding plane and is equidistant from the axes of the two shafts (7, 10).
6. The heads according to claim 5, characterized in that said gasket is shaped substantially like said network of slots (22) and separates
hermetically the high-pressure portion from the low-pressure portion of the hydraulic
pump and motor.
7. The heads according to claim 1, characterized in that said open cavity (6) of the base has a portion (14) with a larger diameter in the
region that is directed outward, when assembled, and another portion (13) that has
a diameter that is substantially equal to the diameter of said protruding shaft.
8. The heads according to claim 7, characterized in that at least one bearing and one sealing ring (15) adapted to prevent oil leakage are
coupled in said portion (14) having a larger diameter of the open cavity (6) of the
base (3).
9. The heads according to claim 8, characterized in that said sealing ring (15) adapted to prevent oil leaks is associated with a second high-pressure
sealing ring in application to motors.
10. The heads according to claim 2, characterized in that said cavities of the cover are mutually connected by means of a connecting duct (21).
11. The heads according to claim 10, characterized in that said duct (21) is obtained by providing a hole in the bottom of said cavities (19,
20) at the region where said slots are closest, with a direction that is inclined
outward and converges toward the center, of said cover (2).
12. The heads according to claim 1, characterized in that said cover (2) has a rectangular contour and is symmetrical with respect to both
central planes.
13. The heads according to claim 12, characterized in that two complementary cavities (24, 25) are provided along the plane of symmetry of the
long side of said rectangular contour and are symmetrical with respect to the other
plane of symmetry.
14. The heads according to claim 13, characterized in that said complementary cavities (24, 25) are shaped like a circular sector with an obtuse
central angle.
15. The heads according to claims 2, 8, 9 and 11, characterized in that said oil draining means (26) are constituted by an opening (26), which connects one
of said two complementary cavities (24) to the bottom of said duct (21) for connecting
said cavities (19, 20), said opening (26) being adapted to have oil flowing through
it, draining said oil toward the inside of the pump and the motor.
16. The heads according to claim 13, characterized in that said opening (26) is threaded and is adapted to accommodate a plug.
17. The heads according to claims 1, 2 and 8, characterized in that said oil draining means are constituted by a channel (28) on the outer wall of said
cover (2), which interferes with one of said cavities (19, 20) and is a through channel,
adapted to drain the oil externally, in one of its portions.
18. The heads according to claim 16, characterized in that said channel is threaded and is adapted to accommodate a threaded plug (29) with
an O-ring for closing said drainage.
19. The heads according to claim 2, characterized in that said internal shaft (9) is hollow (18) and connects the respective cavities of the
cover (2) and of the base (3).
20. The heads according to claim 19, characterized in that said blind cavity (17) of the base (3) is reached by a passage (16) for the oil that
arrives from said larger-diameter portion (14) of the open cavity (16) of the base
(3), to which at least one bearing and at least one sealing ring (15), adapted to
prevent oil leaks, are coupled.