EP4074985A1

EP4074985A1 - Double-acting hydraulic cylinders

Info

Publication number: EP4074985A1
Application number: EP22167896.4A
Authority: EP
Inventors: Luca FRANZONI; Guerrino FRANZONI
Original assignee: Oleodinamica Impianti Srl
Current assignee: Oleodinamica Impianti Srl
Priority date: 2021-04-12
Filing date: 2022-04-12
Publication date: 2022-10-19
Also published as: IT202100009089A1

Abstract

A double-acting hydraulic cylinder which can be connected to means for supplying and discharging a working fluid, comprising a jacket (10) internally comprising a working chamber (30) having a longitudinal extension defining an axis (X) and a plunger (20) sealingly inserted into the jacket (10) to partition said working chamber (30) into at least one first and second variable volume half-chamber (100, 200). The plunger (20) and the jacket (10) are mutually slidable along the axis (X) between at least one first operative position and a second operative position. The cylinder includes a locking device (500) for blocking the mutual sliding of the plunger (20) and of the jacket (10) which can be removably inserted into the jacket (10).

Description

Field of the invention

The present invention generally relates to the technical field of hydraulic cylinders, and it particularly relates to a lockable double-acting hydraulic cylinder.

State of the Art

Double-acting hydraulic cylinders, that is cylinders in which the sliding is controlled in both the sliding directions of the plunger, and in particular compact cylinders, are known.
As known, in order to regulate the inflow/outflow of oil from the cylinder, oil circuits comprising pumps and a plurality of ducts and fittings for fluidically connecting the pumps with the cylinder, are provided for.
It is clear that such systems have large overall dimensions which hinder operators in proximity of the machine in which the cylinder is installed.
Therefore, to this end, circuits in which the ducts are relatively very long so as to position the pumps and the motors away from the cylinder, are generally used.
In order to overcome the response delay between the control of the pump of the hydraulic circuit, for example shutting off the flow, and the ensuing action of the plunger, for example blocking the sliding, there is known the use of one or more "blocking valves" arranged externally along the ducts in proximity of the cylinder.
The drawback of such systems lies in the fact that it is particularly cumbersome, given that the circuits and the fittings in proximity of the blocking valve require a minimum radius of curvature due to the high oil pressures inside the ducts
Furthermore, the use of such blocking valves entails the use of a plurality of fittings, each of which must be mounted and closed correctly as well as constantly monitored to avoid leakage. A leak could mean, for example, that a pressing machine closes unintentionally, with all the ensuing risks.
Lastly, such blocking valves must necessarily be positioned at a certain distance from the cylinder both for safety reasons (it is necessary to prevent an operator or a machine from impacting against such blocking valves) and for practicability and encumbrance purposes, therefore resulting in a response delay between the blocking action and the actual blocking of the plunger.

Summary of the invention

An object of the present invention is to at least partly overcome the aforementioned drawbacks, by providing a hydraulic cylinder that is highly functional, easy to manufacture and cost-effective.
Another object of the present invention is to provide a lockable hydraulic cylinder.
Another object of the present invention is to provide a lockable hydraulic cylinder that is particularly safe.
Another object of the present invention is to provide a lockable hydraulic cylinder with small overall dimensions.
Another object of the present invention is to provide a lockable hydraulic cylinder with low response delay.
A further object of the present invention is to provide a locking device that is highly functional, easy to manufacture and cost-effective.
Another object of the present invention is to provide a locking device with particularly small overall dimensions.
Another object of the present invention is to provide a locking device that is easy to assemble.
These and other objects that will be more apparent hereinafter, are attained by a hydraulic cylinder as described, illustrated and/or claimed herein.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent in light of the detailed description of some preferred but non-exclusive embodiments of the invention, illustrated by way of non-limiting example with reference to the attached drawings, wherein:

FIGS. 1, 2A and 2B are respectively a front, top and lateral view of a hydraulic cylinder 1;
FIGS. 3 , 5 and 7 are a lateral cross-sectional view of the hydraulic cylinder 1 in different operating steps;
FIGS. 4 , 6 and 8 are an enlarged view of some details of a locking device 500 in the configurations corresponding to the configurations of the cylinder of respectively FIGS. 3, 5 and 7;
FIGS. 9, 10 and 11 are respectively a front, top and lateral view of a different embodiment of a hydraulic cylinder 1;
FIGS. 12, 13 and 14 are respectively a front, top and lateral view of a different embodiment of a hydraulic cylinder 1;
FIGS. 15, 16 and 17 are respectively a front, top and lateral view of a different embodiment of a hydraulic cylinder 1;
FIG. 18 is a lateral cross-sectional view of a different embodiment of a hydraulic cylinder 1;
FIG. 19 is a cross-sectional view of an embodiment of the locking device 500 which can be used in a hydraulic cylinder 1;
FIG. 20 is an exploded view of the locking device 500;
FIG. 21 is a partially cross-sectional view of a different embodiment of the locking device 500.

Detailed description of some preferred embodiments

With reference to the attached figures, herein described is a hydraulic cylinder 1. This hydraulic cylinder 1 can be used in actuation systems.
Essentially, the cylinder 1 may therefore comprise a jacket 10 and a plunger 20 inserted in the jacket 10. The jacket 10 and the plunger 20 may therefore slide mutually.
For the sake of simplicity, hereinafter reference will be made only to the sliding of the plunger 20 with respect to the jacket 10.
The sliding of the plunger 20 may be promoted by a working fluid, for example oil, in a per se known manner. In particular, the cylinder 1 may preferably be a so-called "double-acting" cylinder, that is it may be effective in both the sliding directions of the plunger 20.
The cylinder 1 may therefore internally comprise a working chamber 30 inside which the piston 20 may slide. The working chamber 30 can be a fluidically-closed chamber, and the oil may flow thereinto or therefrom only by means of suitable openings and circuits, as better explained hereinafter.
In particular, the jacket 10 may comprise a substantially cylindrical blind hole 11 which may define an axis X. On the other hand, the plunger 20 may sealingly slide into the blind hole 11 along the same axis X. The blind hole 11 may therefore define the working chamber 30.
The working chamber 30 may comprise a lateral surface 33 and a pair of bottom walls 31 and 32. In a per se known manner, the plunger 20 may comprise a stem 21 which may pass through one of the bottom walls 31. In this case, a closing element 40 which is sealingly coupled to the jacket 10 may be provided for, and it may cooperate with the hole 11 in order to internally define the working chamber 30.
The plunger 20 may be sealingly inserted into the working chamber 30 so as to partition it into at least one first half-chamber 100 and one second half-chamber 200. The half- chambers 100 and 200 may have a variable volume.
For example, the plunger 20 may slide between at least one end-of-stroke position in which the half-chamber 100 has a maximum volume and the half-chamber 200 has a minimum volume and at least one start-of-stroke position in which the half-chamber 100 has a minimum volume and the half-chamber 200 has a maximum volume.
FIGS. 3, 5 and 7 show different positions of the plunger 20 in the chamber 30. In particular, FIG. 3 shows a position close to the end-of-stroke position, FIG. 7 shows a position close to the start-of-stroke position, while FIG. 5 shows an intermediate position between the previous ones.
The cylinder 1 may comprise an opening 111 which can be fluidically connected with external hydraulic circuits, an opening 112 fluidically connected with the working chamber 100 and a hydraulic circuit 110 extending between the openings 111 and 112. The cylinder 1 may further comprise an opening 211 which can be fluidically connected with external hydraulic circuits, an opening 212 fluidically connected with the working chamber 200 and a hydraulic circuit 210 extending between the openings 211 and 212.
Preferably, the jacket 10 may comprise the openings 111, 211 and 112, 212. In particular, the operating chamber 30 may include the openings 112, 212, so that they allow the oil to flow into or out from the half- chambers 100, 200.
The openings 111, 211 may be accessible from the outside so that they can be fluidically connected with an external hydraulic circuit. Coupling means of the known type may be possibly provided for arranged at the openings 111, 211 so as to allow the connection of the latter with such external hydraulic circuits. Preferably, the openings 111, 211 may be arranged on the same face of the jacket 10.
According to a particular aspect of the invention, the cylinder 1 may be substantially parallelepiped-shaped so that the overall dimensions are particularly small. It is clear that the cylinder 1 may be substantially cylindrical-shaped without departing from the scope of protection of the present invention.
Preferably, the jacket 10 may have a pair of base surfaces 12, 13 and a lateral surface 14 interposed between the base surfaces 12, 13. The latter may be substantially perpendicular to the axis X, while the lateral surfaces 14 may all be parallel to the axis X.
Preferably, the jacket 10 may be parallelepiped-shaped and the lateral surfaces 14 may be four lateral faces.
The base surface 12 may comprise the hole 11. The openings 111, 211 may be arranged at the lateral surface 14 of the jacket 10, both for example on one of the faces of the surface 14.
The openings 112, 212 may be arranged in proximity of the bottom wall 31, 32 of the operating chamber 30. For example, should the half-chamber 100 comprise the stem 21 of the plunger 20, the lateral surface 33 of the chamber 30 may comprise the opening 112 which may be in proximity of the bottom wall 31. On the other hand, the opposite bottom wall 32 of the chamber 30 may comprise the opening 212.
In other words, the circuits 110, 210 may be inside the jacket 10.
The cylinder 1 may comprise at least one device 500 for blocking the sliding of the plunger 20. Thanks to such device 500, advantageously, the plunger 20 may be blocked in any position. For example, in the start-of-stroke position, the end-of-stroke position or in one or more intermediate positions.
In general, the locking device 500 may interact with the circuits 110, 210 so as to selectively allow/prevent the through-flow of the oil therethrough and thus allow/prevent the inflow or the outflow of the oil into/from the half- chambers 100, 200 and therefore allow or prevent (that is block) the sliding of the piston 20.
Preferably, the jacket 10 may comprise a seat 15 for such locking device 500. The latter may be removably insertable/removable into/from the seat 15 as better explained hereinafter.
In particular, once inserted into the seat 15, the locking device 500 may be inside the jacket 10 and therefore in proximity of the half- chambers 100, 200. Thanks to this characteristic, the response delay can be particularly low, almost zero.
One or both of the circuits 110, 210 may comprise the seat 15. In this manner, the oil flowing between the openings 111, 211 and 112, 212 may pass through the seat 15 so as to shut off the locking device 500.
Suitably, the seat 15 may comprise a pair of openings 113 114 fluidically connected respectively with the openings 111 and 112 and a pair of openings 213, 214 fluidically connected respectively with the openings 211 and 212.
Advantageously, therefore, the hydraulic circuits 110, 210, and preferably also the locking device 500, may remain inside the jacket 10. Thanks to this characteristic, the cylinder 1 may be extremely compact, have small overall dimensions, and it may be particularly safe. Furthermore, this may allow to prevent accidental damage caused by an operator or by a machine from affecting the ducts of the locking means, causing the release of the plunger with the possible serious consequences resulting therefrom.
The jacket 10 may comprise a hole 16 defining the seat 15. In other words, the locking device 500 may be inserted in the hole 16 in a removable manner.
The locking device 500 and the hole 16 may be mutually configured so that once the locking device 500 has been inserted into the hole 16, the former shuts off the oil flowing through the circuits 110, 210.
Preferably, the hole 16 may be substantially cylindrical-shaped.
The hole 16 may define an axis X' which may - preferably but not exclusively - be parallel to the axis X of the chamber 30, for example as shown in FIG. 5. Possibly, the hole 16 may be configured so that the axis X' is substantially perpendicular to the axis X, for example as shown in FIG. 18.
Preferably, the locking device 500 may be substantially cylindrical-shaped defining an axis Y. Preferably, once the locking device 500 has been inserted in the hole 16, the axes Y and X' may substantially coincide.
In particular, for example as schematically shown in FIGS. 1, 9, 12 and 15, the axis Y of the hole 16 may be substantially parallel to the sliding axis X and spaced therefrom. On the other hand, as schematically shown in FIG. 18, the axis Y of the hole 16 may be substantially perpendicular to the axis X.
The seat 15 and the locking device 500 may be mutually configured so that the latter remains entirely contained in the seat 15 so as not to protrude from the jacket 10.
Advantageously, the blind hole 16 may be cylindrical and it may have - on one side - the circular bottom wall 162 and - on the opposite side - a circular opening 163 so to allow the insertion of the locking device 500.
The surface 13 or 14 may comprise such opening 163. Preferably, the surface 13 opposite the surface 12 may comprise such opening 163.
The locking device 500 may be removably inserted into the hole 16 through the opening 163.
This characteristic may allow an easy maintenance of the cylinder and/or replacement of the locking device 500, which is the most sensitive and less durable part. Furthermore, the opening 163 may always remain accessible from outside, allowing the disengagement of the locking device 500 without having to disassemble the cylinder or the plunger 20 or open the jacket 10.
The locking device 500 and the hole 16 may be mutually sized so that the locking device 500 may remain inside the hole 16 so as not to protrude from the surface 13. For example, the locking device 500 may have a length substantially equal to or slightly smaller than the length of the hole 16.
Suitably, a closing element 570 may be provided for to keep the locking device 500 in the hole 16. For example, the closing element 570 may be a threaded plug screwed into the hole 16 which may comprise a corresponding counter-threading.
The plug 570 may possibly protrude from the hole 16 so as to have a vacant end 575 accessible by the operator. In this case, advantageously, such end 575 may facilitate the operations for removing the locking device 500 from the hole 16.
The plug 570 may be sealingly screwed at the end 163 so that the hole 16 - once closed - may define a working chamber.
Suitably, the hole 16 may comprise the openings 113, 114 and 213, 214. Preferably, the hole 16 may be cylindrical and the openings 113, 114 and 213, 214 may be arranged at the lateral surface 161 or at the bottom wall 162 thereof.
Suitably, ducts 115, 215 may be provided for to fluidically connect the openings 111, 211 with the openings 113, 213. Preferably, such ducts may be inside the jacket 10, for example obtained in the body of the jacket by drilling.
Similarly, ducts 116, 216 may be provided for to fluidically connect the openings 112, 212 with the openings 114, 214. Preferably, such ducts may be inside the jacket 10, for example obtained in the body of the jacket by drilling.
In particular, the jacket 10 may comprise a hole 19 defining an axis Z substantially perpendicular to the axis X' of the hole 16 having one end defining the opening 112 and comprising the opening 114. In other words, the duct 116 may comprise or consist of the hole 19. The circuit 110 may include the hole 19.
On the other hand, the jacket 10 may comprise a hole 18 defining an axis Z' substantially perpendicular to the axis X' of the hole 16 and passing through the same which may comprise the opening 214. In other words, the duct 216 may comprise or consist of the hole 18. The circuit 210 may include the hole 18.
Such openings are observable in Fig. 3, which shows the cylinder 1 in which the locking device 500 is removed from the seat 15.
On the other hand, the locking device 500 may comprise a pair of circuits 510, 520 which may preferably be fluidically independent with respect to each other.
Suitably, once the locking device 500 has been inserted in the seat 16, the circuit 510 may be fluidically connected with the circuit 110, while the circuit 520 may be fluidically connected with the circuit 210.
Advantageously, the locking device 500 may therefore be configured so that once inserted in the hole 16, the openings 113, 114 and 213, 214 are in fluidic communication with the circuits 510 and 520.
In particular, the locking device 500 may therefore comprise at least one pair of openings 511, 512 and one pair of openings 521, 522. Preferably, such openings may be at the lateral surface or at the bottom wall of the locking device 500. The circuit 510 may include the openings 511, 512, while the circuit 520 may include the openings 521, 522.
Suitably, once the locking device 500 has been inserted into the hole 16 , the openings 113, 114, 213, 214 may remain in fluidic communication with the openings 511, 512, 521, 522 respectively. In other words, once the locking device 500 has been inserted, the circuit 110 may comprise the openings 111, 112, 113, 114, 511, 521, while the circuit 210 may comprise the openings 211, 212, 213, 214, 521, 522.
Suitably, the locking device 500 may be configured so that the operation thereof is independent from the rotation thereof with respect to the axis X', that is with respect to the rotation around itself along the axis Y. In other words, the openings 511, 512, 521, 522 may be configured so that they are fluidically connected with the openings 113, 114, 213, 214 irrespective of the rotation of the locking device 500 with respect to the axis X'.
Thanks to this characteristic, the locking device 500 may be easy to position in the hole 16. Furthermore, centring means and/or means for hindering the rotation of the locking device 500 inside the hole 16 are not required.
More particularly, as shown in FIG. 19, the openings 511 and 521 may be fluidically connected with the openings 113 and 213 by means of a peripheral conduit 513, 523 defined by an annular recess of the locking device. The openings 512 and 522 may remain at the opposite bottom walls of the locking device 500. Preferably, the openings 512 and 522 may be substantially coaxial to the axis Y. A respective peripheral conduit 514, 524 may therefore be provided to place the openings 512 and 522 in fluidic communication with the openings 114 and 214.
The locking device 500 may be sealingly inserted into the hole 16. Therefore, once the locking device 500 has been inserted into the hole 16, the openings 113, 114, 213, 214 and the openings 511, 512, 521, 522 may be mutually corresponding, for example the former facing the latter.
Suitably, sealing means, for example O-rings, may be provided for so as to allow such sealing insertion. For example, one or more O-rings may be provided for arranged between the outer surface of the locking device 500 and the inner surface of the hole 16. Preferably, three O-rings may be provided so that each of the annular recesses 513, 523 is interposed between a pair of O-rings.
Suitably, the locking device 500 may comprise corresponding seats 509 for the O-rings.
The locking device 500 may comprise valve means 515 and 525 acting respectively on the circuit 510 and 520 so as to selectively allow/hinder the through-flow of the fluid inside the circuits 510 and 520. In particular, the valve means 515 and 525 may be selectively openable/closable so as to allow/hinder the through-flow of the fluid inside the circuits 510 and 520.
In greater detail, the circuits 510 and 520 may comprise an opening for the through-flow of the fluid 516, 526 interposed between openings 511 and 512, 521 and 522. The valve means 515 and 525 may act on the respective openings 516, 526 to selectively allow/hinder the flow of the fluid therethrough.
The valve means 515, 525 may preferably be of the normally closed type.
Suitably, the valve means 515, 525 may comprise a shutter 515' 525' and elastic means 515" 525"acting on the shutter 515' 525' to keep the latter closed, that is so that it closes the through-flow of the respective openings 516, 526 as described above.
Suitably, the circuits 510, 520 may include a respective working chamber 517, 527 which may house the respective shutters 515' 525'. Possibly, the working chamber 517, 527 may also house the elastic means 515" 525".
The working chamber 517, 527 of one or both circuits 510, 520 may have an extension substantially coaxial with the axis Y. The working chamber 517, 527 of one or both circuits 510, 520 may be substantially cylindrical.
According to a particular preferred but non-exclusive embodiment of the invention, the shutters 515' 525' and the elastic means 515" 525" may be movable along the axis Y.
Possibly, the openings 516, 526 may define the openings 511 and 521 or the openings 512 and 522. In any case, the openings 516, 526 may be fluidically connected to the openings 511, 512 and 521, 522.
Preferably, the openings 512 and 522 may be in proximity of the ends 501, 502 of the locking device 500, while the openings may be spaced from the ends along the axis Y. In other words, the circuits 510 and 520 may have an extension along the axis Y.
Preferably, the valve means 515, 525 may be configured to operate in a substantially opposite manner, that is elastic means 515" - for example a spiral spring - may force the shutter 515' toward the opposite end 502 while the elastic means 525" - for example a spiral spring - may force the shutter 525' toward the opposite end 501.
The circuits 510 and 520 may be fluidically independent.
Suitably, when the valve means 515, 525 are closed, oil may be hindered from flowing through the respective openings 516, 526 and therefore through the respective circuits 510, 520, while when the valve means 515, 525 are open, the oil may be allowed to flow through the respective openings 516, 526 and therefore through the respective circuits 510, 520.
According to a preferred but not exclusive embodiment, the valve means 515 may be configured to open when the oil flows into the opening 511 therefore so as to allow the oil to flow out from the opening 511 to the opening 512, while they may be configured to remain closed when the oil flows into the opening 512 therefore so as to hinder the oil from flowing out from the opening 512 to the opening 511. Similarly, the valve means 525 may be configured to open when the oil flows into the opening 521 so as not to shut the opening 526 and therefore allow the oil to flow through the opening 521 to the opening 522, while they may be configured to remain closed when the oil flows into the opening 522 so as to shut the opening 526 and therefore prevent the oil from flowing from the opening 522 to the opening 521.
In other words, the flow of oil may overcome the action of the spring 515", 525" so as to promote the sliding of the shutter 515', 525' inside the chamber 517, 527 so as to move it away from the opening 516, 526 and therefore allow the oil to flow through it.
Although hereinafter reference will be made to such configuration described above, it is however clear that the valve means 515, 525 may be configured in an opposite manner, that is so that the flow of oil coming from the openings 512, 522 allows the opening of the valve means 515, 525 and therefore the flow of oil from the openings 512, 522 to the openings 511, 521 , while they may prevent the flow of oil from the openings 511, 521 to the openings 512, 522 without departing from the scope of protection of the present invention.
In order to allow the oil to flow from the opening 512 and/or 522 to the opening 511 and/or 521 through the respective circuits 510 and 520, one may selectively act on the respective valve means 515, 525 so as to selectively open them and therefore allow the fluid to flow through the opening 516, 526 from the respective opening 512, 522 to the respective opening 511, 521.
The locking device 500 may therefore comprise a slider element 530 configured to act on one or both of the valve means 515, 525 to selectively open the latter.
Suitably, the slider element 530 may be configured to alternately act on one or on the other of the valve means 515, 525.
For example, the slider 530 may be interposed between the valve means 515, 525 and it may therefore be movable between at least one operative position in which it interacts with the valve means 515 and at least one operative position in which it interacts with the valve means 525. Preferably, the slider 530 may be movable in a further inoperative position in which it does not interact with the valve means 515 and does not interact with the valve means 525.
Suitably, the slider 530 may comprise a protuberance 531 designed to interact with the valve means 515 and in particular with the shutter 515' to promote the sliding thereof in the working chamber 517 and therefore to space it apart from the opening 516 so as to allow the oil to flow through it. Similarly, the slider 530 may comprise a protuberance 532 designed to interact with the valve means 525 and in particular with the shutter 525' to promote the sliding thereof in the working chamber 527 and therefore to space it apart from the opening 526 so as to allow the oil to flow through it.
The protuberance 531, 532 may have a smaller cross-section with respect to the respective opening 516, 526 so as to allow the insertion of the former into the latter without preventing the flow of oil through the respective opening 516, 526.
Advantageously, the slider 530 may have a length such that when it is in the inoperative position, both the protuberances 531 and 532 may remain spaced apart from the shutters 515' and 525'.
In particular, in the absence of inflowing oil, the action of the springs 515" and 525" may promote the sliding of the shutters 515' and 525' and therefore the sliding of the slider 530 in an intermediate position between the operative positions, that is in the inoperative position.
For example as shown in FIG. 19, the slider 530 may be slidable along the axis Y between the operative and inoperative positions described above. For example, the slider 530 may have a substantially cylindrical-shaped main body 533 with a pair of opposite walls 534, 535, while the protuberances 531, 532 may extend on opposite sides of the cylindrical body 533, preferably from the opposite walls 534, 535.
Suitably, the locking device 500 may comprise a working chamber 536 fluidically connected with the opening 511 and the opening 516. Preferably, the working chamber 536 may comprise the opening 511, the shutter 515' and the wall 534 of the slider 530. Therefore, the inflow of the oil into the working chamber 536 from the opening 511 may promote the sliding of the shutter 515' and the sliding of the wall 534, and therefore the opening of the valve means 515 and the sliding of the slider 530 from an operative position toward the opposite operative position, for example toward the valve means 525. In the absence of oil flowing in from the opening 511, the valve means 515 will close due to the action of the spring 515".
Similarly, the locking device 500 may comprise a working chamber 537 fluidically connected with the opening 521 and the opening 526. Preferably, the working chamber 537 may comprise the opening 521, the shutter 525' and the wall 535 of the slider 530. Therefore, the inflow of the oil into the working chamber 537 from the opening 521 may promote the sliding of the shutter 525' and the sliding of the wall 535, and therefore the opening of the valve means 525 and the sliding of the slider 530 from an operative position toward the opposite operative position, for example toward the valve means 515. In the absence of oil flowing in from the opening 521, the valve means 525 will close due to the action of the spring 525".
Preferably, a single working chamber 538 with the openings 511, 521, 516, 526 may be provided for, while the slider 530 may be sealingly inserted into the chamber 538 to partition it into the chambers 536 and 537. Therefore, the sliding of the slider 530 between the operative positions may correspond to the increase of the volume of one chamber and the decrease of the volume of the other and vice versa.
Suitably, the chamber 538 may comprise a pair of opposite abutment surfaces 539 to define the end-of-stroke of the slider 530 corresponding to an operative position and to the opposite operative position.
Advantageously, the inflow of oil into the opening 511 may therefore correspond both to the sliding of the actuator 515' (and therefore the opening of the valve means 515 so as to allow the oil to flow from the opening 511 to the opening 512) and the sliding of the slider 530 toward the valve means 525 and therefore the resulting sliding of the actuator 525' due to the protuberance 532 (and therefore the forced opening of the valve means 525 so as to allow the oil to flow from the opening 522 to the opening 521).
Similarly, the inflow of oil into the opening 521 may therefore correspond both to the sliding of the actuator 525' (and therefore the opening of the valve means 525 so as to allow the oil to flow from the opening 521 to the opening 522) and the sliding of the slider 530 toward the valve means 515 and therefore the resulting sliding of the actuator 515' due to the protuberance 531 (and therefore the forced opening of the valve means 515 so as to allow the oil to flow from the opening 512 to the opening 511).
Should there be no flow of oil flowing into both openings 511, 521, the slider 530 will be in the inoperative position and the valve means 515, 525 will be closed. The possible inflow of oil from the openings 512 and 522 will not activate the valve means 515, 525 which may remain closed and therefore the oil will be hindered from flowing through the respective openings 516, 526.
Therefore, with regard to the description outlined above, the locking device 500 may therefore be a device for allowing the oil to flow from the opening 511 to the opening 512 and correspondingly from the opening 522 to the opening 521 when the opening 511 defines an inlet for the oil, or for allowing the oil to flow from the opening 521 to the opening 522 and correspondingly from the opening 512 to the opening 511 when the opening 521 defines an inlet for the oil, and so as to hinder the oil from flowing from the opening 512 and/or 522 to the respective openings 511, 521 when the latter do not define the inflow of the oil.
Such locking device 500 may consist of several elements. In particular, the locking device 500 may comprise at least one element 540, one element 550 and one element 560.
The elements 540, 550, 560 may be mutually couplable along the axis Y so as to assemble the locking device 500. Preferably, the elements 540, 550, 560 may all be substantially cylindrical-shaped.
The device 500 may be assembled in the cylinder 1, for example in the hole 16 by sequentially inserting the elements 550, 540, 560 or 560, 540 and 550.
On the other hand, the device 500 may be pre-assembled. The elements 550, 540, 560 can be coupled to each other, and inserted in the hole 16 only subsequently. Such coupling may be of the removable type.
The elements 540, 550 and 560 may be coupled removably, as schematically shown in FIG. 19. On the other hand, according to a particular embodiment, a cover 590 may be provided for. In particular, the locking device 500 may comprise the cover 590 suitable to internally retain the elements 540, 550 and 560.
Possibly, the locking devices 500 may have different configurations. Suitably, different locking devices 500 may be inserted alternately so that the cylinder 1 behaves differently depending on the needs.
In any case, once the elements 540, 550 and 560 have been assembled, the latter may be fluidically connected so as to define the circuits 510, 520 and the valve means 515, 525 described above.
In greater detail, the element 550 which may include the hydraulic circuit 510 and the valve means 515, the element 560 which may include the hydraulic circuit 520 and the valve means 525 and the element 540 which may comprise the slidable slider 530.
The element 550 may comprise an internally hollow cylindrical body 551 so as to define the chamber 517 which may house the spring 515" and the shutter 515'. The body 551 may further comprise a bottom wall 552 and an opening 553 opposite to the bottom wall 552. Similarly, the element 560 may comprise an internally hollow cylindrical body 561 so as to define the chamber 527 which may house the spring 525" and the shutter 525'. The body 561 may further comprise a bottom wall 562 and an opening 563 opposite to the bottom wall 562.
Advantageously, the spring 515" and the shutter 515' and the spring 525" and the shutter 525' may be inserted into the respective chamber 517 and 527 through the opening 553 and 563. Suitably, a plug element 555 and 565 may be provided for so as to close the respective chamber 517 and 527. Possibly, the plug element 555 565 may include the respective opening 512 and 522.
Suitably, the elastic means 515" and 525" may abut against the plug 555, 565 to force the respective shutter 515' 525' to close against the opening 516, 526.
The cylindrical bodies 551 and 561 may comprise a respective annular recess 551' and 561' defining the peripheral conduits 513 and 523.
The element 540 may comprise an internally hollow cylindrical body 541 for housing the slider 530. Preferably, the slider 530 may sealingly slide in the hollow cylindrical body 541.
Possibly, as schematically shown in FIG. 19, the elements may be coupled axially along the axis Y. Should the cover 590 be present, the elements 540 550 and 560 may be inserted into the cover 590. Preferably, the cover 590 may be substantially tubular so that the elements 540 550 and 560 may be inserted thereinto along the axis Y.
Once elements 540 550 and 560 have been inserted into the cover 590, they may be coupled "in a pack-like manner" by means of a plug in a per se known manner so as to assemble the locking device 500.
Once assembled, the locking device 500 may therefore define a single piece. For example, it may be marketed separately from the jacket 10 and plunger 20.
The sliding of the plunger 20 may therefore correspond to the volume change in the half- chambers 100 and 200 and therefore to the through-flow of the oil through the circuits 110, 210. When the through-flow is allowed, the half- chambers 100 and 200 may change the volume thereof and therefore the plunger 20 may slide, while when the through-flow is hindered the plunger will not slide.
In particular, as better explained hereinafter, given that the openings 512 and 522 may be connected to the half- chambers 100 and 200, the outflow of the oil from the latter without the introduction of oil into the openings 511 or 521 (and therefore 111 and 211) can be hindered, thus blocking the sliding of the plunger 20 in both directions.
FIGS. 3 and 4 show a configuration of the cylinder 1 in which the plunger 20 is moving from the end-of-stroke position to the start-of-stroke position and correspondingly the locking device 500 is in an operative configuration (FIG.4). In this case, the oil flows in through the opening 211 and therefore through the opening 521, promoting the sliding of the actuator 525' toward the right and acting on the wall 535 to promote the sliding of the slider 530 toward the left. The protuberance 531 of the latter may act against the shutter 515. Therefore, the oil will flow from the opening 521 to the opening 522 and then through the opening 212 into the half-chamber 200. Simultaneously, the oil may flow out from the half-chamber 100 through the opening 112 and therefore flow through the opening 512 into the chamber 517, flow through the opening 516 kept open by the slider and flow out from the opening 511 and therefore from the opening 111.
FIGS. 7 and 8 show a configuration of the cylinder 1 in which the plunger 20 is moving from start-of-stroke position to the end-of-stroke position and correspondingly the locking device 500 is in a different operative configuration (FIG. 7). In this case, the oil flows in through the opening 111 and therefore through the opening 511, promoting the sliding of the actuator 515' toward the left and acting on the wall 534 to promote the sliding of the slider 530 toward the right. The protuberance 532 of the latter may act against the shutter 525. Therefore, the oil will flow from the opening 511 to the opening 512 and then through the opening 112 into the half-chamber 100. Simultaneously, the oil may flow out from the half-chamber 200 through the opening 212 and therefore flow through the opening 522 into the chamber 527, flow through the opening 526 kept open by the slider 530 and flow out from the opening 521 and therefore from the opening 211.
FIGS. 5 and 6 show a configuration of the cylinder 1 in which the plunger 20 is blocked. As a matter of fact, when there is no flow of oil into the openings 111 or 211, the locking device is in the inoperative configuration in which it does not allow the oil to flow from the openings 512 and 522 to the openings 511 and 521 and therefore does not allow the oil to flow out from the half- chambers 100 and 200. A similar configuration is shown in FIG. 18 in which the axis X' is perpendicular to the sliding axis X of the plunger 20.
The configurations of the circuits 110, 210 may possibly change, for example the conduits 115, 215 and 116, 216 may have different length and path and/or the openings 111, 211 and 112, 212 may have different positions, without departing from the scope of protection of the present invention.
In the light of the above, it is clear that the invention attains the pre-set objectives.
The invention is susceptible to numerous modifications and variants all falling within the inventive concept outlined in the attached claims. All details can be replaced by other technically equivalent elements, and the materials can be different depending on the technical needs, without departing from the scope of protection of the invention.
Even though the invention has been described with particular reference to the attached figures, the reference numerals used in the description and in the claims are meant for improving the intelligibility of the invention and thus do not limit the claimed scope of protection in any manner whatsoever.

Claims

A compact double-acting hydraulic cylinder which can be connected to means for supplying and discharging a working fluid, comprising:
- a jacket (10) internally comprising a working chamber (30) having a longitudinal extension defining a first axis (X);

- a plunger (20) sealingly inserted into said jacket (10) to partition said working chamber (30) into at least one first and second variable volume half-chamber (100, 200);
wherein said plunger (20) and said jacket (10) are mutually slidable along said first axis (X) between at least one first operative position in which said first half-chamber (100) has a maximum volume and said second half-chamber (200) has a minimum volume and at least one second operative position wherein said first half-chamber (100) has a minimum volume and said second half-chamber (200) has a maximum volume;

wherein said jacket (10) comprises a first and a second circuit (110, 210) which are mutually fluidically independent extending between a respective first opening (111, 211) which can be fluidically connected with the means for supplying/discharging the working fluid and a second opening (112, 212) fluidically connected with respectively said at least one first (100) and said at least one second (200) half-chamber;

wherein, when said plunger (20) and said jacket (10) mutually slide from said first to said second operative position, the working fluid flows into said second half-chamber (200) through said second circuit (210) and the working fluid in said first half-chamber (100) flows out therefrom through said first circuit (110), and wherein when said plunger (20) and said jacket (10) mutually slide from said second to said first operative position, the working fluid flows into said first half-chamber (100) through said first circuit (110) and the working fluid in said second half-chamber (200) flows out therefrom through said second circuit (210);

wherein the cylinder further comprises a locking device (500), said jacket (10) including a seat (15) for said locking device (500),

wherein said first and second circuit (110, 210) are fluidically connected with said seat (15) so that once said locking device (500) has been inserted into said seat (15), the first is fluidically connected with said first and second circuit (110, 210) to selectively block the mutual sliding of said plunger (20) and said jacket (10);

wherein said locking device (500) can be selectively removably inserted/removed from the outside into/from said seat (15).
Hydraulic cylinder according to claim 1, wherein said jacket (10) comprises a first cylindrical blind hole (16) defining said seat (15), said first blind hole (16) having a third opening (163) accessible from the outside, said locking device (500) being insertable/removable through said third opening (163).
Hydraulic cylinder according to the preceding claim, further comprising a plug (570) which can be sealingly coupled with said jacket (10) at said third opening (163) to close said seat (15), said plug (570) having an end (575) which can be operated by an operator.
Hydraulic cylinder according to claim 2 or 3, wherein said blind hole (16) has a length substantially equal to or slightly greater than said locking device (500).
Hydraulic cylinder according to one or more of claims 2, 3 or 4, wherein said jacket (10) has a first and second opposite outer base surface (12, 13) and an outer lateral surface (14) interposed between said first and second base surfaces (12, 13), the latter being substantially parallel to each other.
Hydraulic cylinder according to the preceding claim, wherein said first base surface (12) comprising a second blind hole (11) for said plunger (20) defining said chamber (30), said second base surface (13) or said outer lateral surface (14) comprising said first blind hole (16) for said locking device (500).
Hydraulic cylinder according to the preceding claim, wherein said second base surface (13) includes said third opening (163), said blind hole (16) defining a second axis (X') substantially parallel to said first axis (X).
Hydraulic cylinder according to any one of the preceding claims, wherein said jacket (10) is a monobloc.
Hydraulic cylinder according to any one of claims 2 to the preceding claim, wherein said locking device (500) includes a third and fourth hydraulic circuit (510, 520), said locking device (500) and said first hole (16) being mutually sized so that once the former (500 ) has been inserted into the latter (16), said first circuit (110) includes said third hydraulic circuit (510) and said second circuit (210) includes said fourth hydraulic circuit (520), said locking device (500) comprising first and second valve means (515, 525) acting on said third and fourth hydraulic circuits (510, 520) to selectively allow/prevent the through-flow of the working fluid therethrough.
Hydraulic cylinder according to the preceding claim, wherein said first hole (16) comprises fourth openings (113, 213) and fifth openings (114, 214) fluidically connected with respectively said first openings (111, 211) and said second openings (112, 212) of said first and second circuit (110, 210), said locking device (500) comprising respective sixth openings (511, 521) and seventh openings (512, 522) in order to allow the inflow/the outflow of the working fluid into/from said third and fourth hydraulic circuit (510, 520), said sixth openings (511, 521) and seventh openings (512, 522) being designed to remain at said fourth openings (113, 213) and fifth openings (114, 214) once said locking device (500) has been inserted into said first hole (16).
Hydraulic cylinder according to the preceding claim, wherein said first blind hole (16) is substantially cylindrical-shaped, said locking device (500) being substantially cylindrical-shaped and being sealingly inserted into said blind hole (16), said locking device (500) having a first and a second annular recess (513, 523) comprising said sixth openings (511, 521).
Hydraulic cylinder according to the preceding claim, comprising a plurality of O-rings interposed between the outer surface of the locking device (500) and the inner surface of said hole (16), said O-rings being arranged so that each of said first and second annular recess (511, 521) is interposed between a pair of O-rings.
Hydraulic cylinder according to claim 10, 11 or 12, wherein said locking device (500) comprises:
- a first element (550) including said third hydraulic circuit (510) and said first valve means (515) acting thereon, selectively openable/closable so as to allow/hinder the through-flow of the fluid through said third circuit (510);

- a second element (560) including said fourth hydraulic circuit (520) and said second valve means (525) acting thereon, selectively openable/closable so as to allow/hinder the through-flow of the fluid through said fourth circuit (520);

- a third element (540) comprising a slider (530) slidable between a first operative position in which it interacts with one of said first and second valve means (515, 525) to open the latter, a second operative position in which it interacts with the other between said first and second valve means (515, 525) to open the latter, and at least one inoperative position in which it does not interact with said first and second valve means (515, 525), said first and second valve means (515, 525) being normally closed;
wherein each of said first, second and third element (550, 560, 540) comprises a seat (509) for housing a respective O-ring;

wherein said first, second and third element (550, 560, 540) are separate pieces which can be mutually coupled along a third axis (Y) to define the locking device (500).
Hydraulic cylinder according to any one of claims 10 to the preceding claim, wherein said jacket (10) comprises a third hole (19) defining a fourth axis (Z) substantially perpendicular to said second axis (X') having an end defining said second opening (112), said third hole (19) comprising one of said fifth openings (114), said first circuit (110) including said third hole (19), and wherein said jacket (10) comprises a fourth hole (18) defining a fifth axis (Z') substantially perpendicular to said second axis (X') passing through said blind hole (16), said fourth hole (18) comprising the other of said fifth openings (224), said second circuit (210) including said fourth hole (18).
Hydraulic cylinder according to any one of claims 9 to the preceding claim, wherein said plug (570) comprises an internal channel (571), said fourth circuit (520) of said locking device (500) including said internal channel (571).