EP4185779A1

EP4185779A1 - Oleodynamic control device

Info

Publication number: EP4185779A1
Application number: EP21737178.0A
Authority: EP
Inventors: Christian Storci
Original assignee: Atlantic Fluid Tech SRL
Current assignee: Atlantic Fluid Tech SRL
Priority date: 2020-07-23
Filing date: 2021-07-06
Publication date: 2023-05-31
Anticipated expiration: 2041-07-06
Also published as: CN115917164A; EP4185779B1; WO2022018549A1; IT202000017854A1

Abstract

It is disclosed an oleodynamic control device with a valve body, a main piston axially movable in the valve body, actuating means operating on a first end of the main piston, a piloting piston that is movable within a piloting chamber inside the valve body, piloting shutter means for controlling a passage of fluid in the piloting chamber, throttling means for generating a throttling towards the piloting chamber, unidirectional means arranged in parallel with respect to the throttling means to allow a flow from the piloting chamber, a piloting auxiliary piston between the main piston and the piloting piston, where the piloting auxiliary piston has a relatively high sealing diameter such to result in a relatively high piloting ratio.

Description

Oleodvnamic control device

Background of the invention

[0001] The invention relates to a control device, in particular a device suitable for controlling an oleodynamic actuator.

[0002] The invention may be used, specifically, though not exclusively, in a hydraulic circuit for controlling a hydraulic motor, with one or two rotation directions, with fixed or variable displacement, in particular for a load lifting apparatus, such as a winch. The invention may in any case be used for controlling an oleodynamic actuator of a different kind, such as a hydraulic cylinder that may be used, in particular, in an earth moving machine.

[0003] It refers in particular to an oleodynamic control device according to the preamble of the first claim, wherein throttling means improve the operation stability and unidirectional means reduce an actuation delay caused by throttling means. Patent Publication EP 2631 517 A1 discloses a similar oleodynamic control device.

[0004] This known control device is however little suitable in some circumstances, especially when a valve device characterised by a high calibration is required - i.e. a device which can be configured such to initiate a flow rate of an operating fluid by starting to open a shutter at a relatively high pressure - and, at the same time, capable of quickly reaching the desired shutter opening position, such to oppose little resistance and thereby reduce energy consumption. Such a circumstance may for instance occur when the oleodynamic actuator to be controlled is a hydraulic motor.

[0005] It is also desirable to further improve the operation stability of the control device of the prior art.

Summary of the invention [0006] An object of the invention is to overcome one or more of the aforesaid limits and drawbacks of the prior art.

[0007] An object is to make available an oleodynamic control device alternative to those of the prior art.

[0008] An advantage is to allow to start opening a flow control shutter at a relatively high pressure.

[0009] An advantage is to provide a control device capable of switching from an initial closing position of the oleodynamic flow to a desired opening position of the flow, in a relatively short time.

[0010] An advantage is to make an oleodynamic control device whose energy consumption is relatively small.

[0011] An advantage is to create a control device capable of reaching a desired valve opening position at a relatively low working pressure.

[0012] An advantage is to provide an oleodynamic control device with a relatively high operation stability.

[0013] An advantage is to allow a precise, stable and reliable control of an oleodynamic actuator, in particular of a hydraulic motor.

[0014] An advantage is to allow a control of an actuator such to avoid or reduce the delay between the instant wherein an operator actuates piloting and the instant wherein the displacement of a movable element of the actuator starts, in particular even when the oleodynamic fluid is more viscous, such as for example in winter.

[0015] Such objects and advantages, and still others, are reached by a control device according to one or more of the hereinbelow reported claims.

[0016] In one embodiment, an oleodynamic control device comprises: a valve body with an internal cavity and a pilot opening; a main piston axially movable in the cavity of the valve body; actuating means arranged at a first end of the main piston; a piloting piston movable in a piloting chamber inside the valve body; shutter means for controlling a passage of fluid between the pilot opening and the piloting chamber; throttling means to generate a throttling between the pilot opening and the piloting chamber; unidirectional means arranged in parallel with respect to throttling means; an auxiliary piloting piston with a first end facing the second end of the main piston and with a second end facing a first end of the piloting piston, wherein at least one sealing diameter of the auxiliary piloting piston is configured such to obtain a construction with a relatively high piloting ratio, such as a piloting ratio greater than 8:1.

[0017] In one embodiment, an oleodynamic control device comprises a valve body, a main piston axially movable in the valve body, actuating means operating on a first end of the main piston, first sealing means to define a first sealing area in the main piston, a piloting piston movable within an internal piloting chamber for controlling a fluid passage into the piloting chamber, throttling means to generate a throttling towards the piloting chamber, unidirectional means arranged in parallel with respect to the throttling means, an auxiliary piloting piston arranged between the main piston and the piloting piston, second sealing means to define a second sealing area on the auxiliary piloting piston. The second sealing area is configured such that the piloting ratio is relatively high, for instance a piloting ratio greater than 8:1.

Brief description of the drawings [0018] The invention will be better understood and implemented with reference to the enclosed drawings which show non-limiting embodiments thereof, wherein:

Figure 1 is a longitudinal section of an example of a control device made according to the present invention;

Figure 2 is a longitudinal section of the device of Figure 1 according to an orthogonal section plane with respect to that of Figure 1 ;

Figure 3 shows an enlarged detail of Figure 2;

Figure 4 is a hydraulic diagram of a working apparatus comprising the control device of Figure 1.

Detailed description

[0019] With reference to the aforesaid figures, an oleodynamic control device is referred to, on the whole, by 1. The control device 1 may be used, in particular, for controlling an oleodynamic actuator. The control device 1 may be used, in particular, in a hydraulic circuit for controlling a hydraulic motor M, such as a hydraulic motor employed in a load lifting apparatus (such as, for example, a winch or the like). The hydraulic motor M may be, in particular, with two rotation directions, with a fixed or variable displacement, etc.

[0020] The control device 1 may comprise, in particular, a valve body 2 with at least one internal cavity for the passage of a fluid. The valve body 2 may comprise, in particular, a block made in a single piece, such as in the example shown, or more pieces being assembled. The valve body 2 may comprise, in particular, at least one first opening 3, or one first door, for the passage of an operative flow rate of an oleodynamic fluid (oil) and at least one second opening 4 or second door, for the passage of an operative flow rate of the oleodynamic fluid.

[0021] The valve body 2 may comprise, in particular, at least one pilot opening P, or pilot door, for the passage of a piloting flow rate that may be used to provide a piloting signal, as will be explained hereinafter. [0022] The openings, or doors, arranged on the valve body 2 allow to connect the control device 1 to an oleodynamic circuit of a working apparatus (see Figure 4), as, in particular, a load lifting apparatus (such as a winch).

[0023] The first opening 3 and the second opening 4 may be configured, in particular, for the passage of the operative flow rate of fluid required to feed a hydraulic actuator. In use, the first opening 3 may serve, e.g for lifting a load, as an entrance for the fluid into the cavity of the valve body 2 and the second opening 4 may serve as an exit for the fluid from the cavity of the valve body 2, and vice versa for lowering a load.

[0024] The control device 1 may comprise, in particular, a main piston 5 axially movable in the cavity of the valve body 2. The main piston 5 is movable, in particular, with the possibility of assuming at least one closing position and at least one opening position. In the opening position the main piston 5 closes a passage section of the fluid through the cavity, where such passage section is arranged between the first opening 3 and the second opening 4. In the opening position the main piston 5 opens the passage section to allow a flow. The passage section may in particular be defined between the shutter of the main piston 5 and an annular seat of a movable body C arranged in the cavity. A spring M may in particular be arranged to push the movable body C (axially sliding) towards the shutter portion of the main piston 5.

[0025] The control device 1 may in particular comprise actuating means 6 arranged at a first end of the main piston 5 to exert an axial force on the main piston 5. Such actuating means 6 may in particular comprise elastic means arranged to push the main piston 5 towards the closing position. Elastic means may in particular comprise a spring.

[0026] The control device 1 may in particular comprise first sealing means 7 arranged on the main piston 5 to define a first sealing area. First sealing means 7 may in particular be defined between the second opening 4 and a second end of the main piston 5 opposite the aforesaid first end. First sealing means 7 may in particular comprise a sealing ring. [0027] The control device 1 may in particular comprise a piloting piston 8 movable in the valve body 2. The piloting piston 8 may be movable, in particular, coaxially with respect to the main piston 5. The piloting piston 8 may be movable, in particular, within a piloting chamber 9 obtained inside the valve body 2 and connected to the pilot opening P. [0028] The control device 1 may comprise, in particular, piloting shutter means 10 arranged to interact (in contact) with the piloting piston 8 to control a passage of a piloting fluid. Such passage is between the pilot opening P and the piloting chamber 9.

[0029] Piloting shutter means 10 may be in particular configured in such a way as to selectively assume at least one open configuration, wherein the piloting shutter means opens the aforesaid passage of piloting fluid, and a closed configuration, wherein the piloting shutter means closes the aforesaid passage of piloting fluid. In this closed configuration, the piloting fluid will flow from the pilot opening P to the piloting chamber 9 passing through throttling means 11 (as will be better explained hereinafter), so as to move an auxiliary piston, as will be better explained hereinafter.

[0030] The control device 1 may comprise, in particular, throttling means 11 arranged to generate a throttling (with a relative limited load loss) between the pilot opening P and the piloting chamber 9.

[0031] The throttling means 11 may comprise, in particular, a closing element coupled with the valve body 2 by means of a threaded connection. Such threaded connection defines a passage of a piloting fluid (in particular a helicoidal- shaped passage) resulting in a throttling.

[0032] The closing element may in particular be provided with adjustment means arranged to adjust screwing the closing element itself, such to consequently adjust the extent of the throttling (i.e., the extent of the load loss located in the throttling) provided by the throttling means 11.

[0033] In other examples, not shown, the throttling means may comprise other types of throttling, such as for example a throttling generated by a set screw, or by a couple of coaxial elements (conical or cylindrical) that are partially fitted into each other such to define an adjustable-size orifice, or by still other devices.

[0034] The control device 1 may in particular comprise unidirectional means 12 arranged in parallel with respect to the throttling means 11. The unidirectional means 12 may be configured, in particular as in these examples, to allow a flow of a piloting fluid from the piloting chamber 9 towards the pilot opening P. In other examples, not shown, the unidirectional means 12 may be configured to allow a reverse flow.

[0035] The unidirectional means 12 may in particular comprise a check valve arranged in the closing element of the throttling means 11.

[0036] The unidirectional means 12 allows quickly filling and emptying the piloting chamber 9. When the operator, for instance, starts a piloted operation, for instance for lifting a load, the main piston 5 will have to open the aforesaid passage section arranged between the first opening 3 and the second opening 4, whereby the piloting chamber 9 will have to be filled rapidly. When the operator, for instance, ends the piloted operation, the main piston 5 will have to obstruct again the passage section between the first opening 3 and the second opening 4, whereby the piloting chamber 9 will have to be rapidly emptied. The unidirectional means 12 further enables a security flow of the piloting fluid towards the pilot opening P when the pressure in the piloting chamber 9 overcomes a predetermined value.

[0037] The control device 1 may comprise, in particular, an auxiliary piloting piston 13 that is movable in the valve body 2. The auxiliary piloting piston 13 may be movable, in particular, coaxially with respect to the main piston 5 and/or coaxially with respect to the piloting piston 8.

[0038] The auxiliary piston 13 may be, in particular, axially comprised between the main piston 5 and the piloting piston 8.

[0039] The auxiliary piston 13 may, in particular, have a first end facing the second end of the main piston 5. The first end of the auxiliary piston 13 may in particular interact in contact with the second end of the main piston 5.

[0040] The auxiliary piston 13 may have, in particular, a second end (for instance opposite to the first end) facing a first end of the piloting piston 8. The piloting chamber 9 may be, in particular, at least partially delimited by the aforesaid second end of the auxiliary piston 13.

[0041] The control device 1 may comprise,, in particular second sealing means 14 arranged on the auxiliary piston 13. The second sealing means 14 may be in particular arranged to define a second sealing area. The second sealing means 14 may comprise in particular a sealing ring. In other examples the second sealing means 14 may comprise a sliding coupling, between the auxiliary piston 13 and the cavity housing the piston, with a clearance such to obtain an appropriate sealing effect, in particular a sealing effect which is in any case suitable to allow gas vent or relief. The second sealing area may be, as in this example, greater than the first sealing area.

[0042] The passage section which is controlled by the main piston 5 may have, as in this example, an area lower than the second sealing area. The passage section which is controlled by the main piston 5 may have, as in this example, an area greater than the first sealing area.

[0043] The auxiliary piston 13 may be in particular at least partially arranged in an auxiliary chamber 15 axially comprised between the first sealing means 7 and the second sealing means 14. The second sealing means 14 may be in particular configured in such a way as to separate the piloting chamber 9 from the auxiliary chamber 15. The auxiliary chamber 15 may be, as in this example, in fluid communication with the first opening 3, or with the external environment. The control device 1 may in particular comprise, a channel

16 configured to fluidically connect the auxiliary chamber 15 with the first opening 3, or with the external environment. The connection channel 16 between the auxiliary chamber 15 and the first opening 3 may be obtained, in particular, inside the main piston 5.

[0044] The first end of the auxiliary piston 13 may be configured, in particular, to interact in contact with the second end of the main piston 5.

[0045] The first end of the auxiliary piston 13 may have, as in this example, a straight cross section with an area lower than the first sealing area.

[0046] The first end of the auxiliary piston 13 may be configured, in particular, to interact in contact with the first end of the piloting piston 8.

[0047] The piloting shutter means 10 may in particular comprises at least one longitudinal element. The piloting shutter means 10 may in particular comprise at least one shutter 17. The piloting shutter means 10 may in particular comprise at least one spring. The longitudinal element may be coupled, in particular, to a valve body 2, such as by a screw coupling. The shutter 17 may be arranged, in particular, inside the longitudinal element. The spring may be arranged, in particular, inside the longitudinal element.

[0048] The aforesaid spring may be configured, as in this example, to push the shutter

17 to a closing position wherein the shutter 17 closes a hole obtained in the longitudinal element. The hole may be in particular communicating with the piloting chamber 9. The piloting piston 8 may be, as in this specific example, partially housed in the hole.

[0049] The control device 1 may comprise, in particular, a brake release valve 18 with a selector valve 19 which may be configured, in particular, to allow disabling a hydraulic parking brake 20 operatively associated to a hydraulic motor M (see Figure 4). The valve device 1 may comprise, in particular, a service opening 21, or service door, which may be, as in this example, for connecting the brake release valve 18 with the hydraulic parking brake 20. [0050] In Figure 4 a diagram of a working apparatus comprising a distributor D and the hydraulic motor M connected to the distributor D is shown. The working apparatus further comprises the control apparatus 1 described above. The control device 1 has been represented by a long-dashed and short-dashed line.

[0051] The working apparatus may comprise, in particular, a pump (of the known type and not represented) connected to the distributor D. The hydraulic motor M may comprise, in particular, a hydraulic motor with two rotation directions. The working apparatus may comprise, in particular, a load lifting apparatus, such as a winch, whose pulling member comprises the hydraulic motor.

[0052] The control device 1 may be used, as said, for controlling the hydraulic motor M (however it could be used for other actuators, such as for an excavator hydraulic cylinder). The control device 1 may be used in particular when a high calibration control valve needs to be used, such as to enable to safely open the control valve and unlock the brake (such as, for instance, the hydraulic parking brake 20) which is normally present in case a hydraulic motor is used.

[0053] In use, an operator may start a piloting operation by a manoeuvring device (not shown, for example a manoeuvring device of the known type), in particular operating on the distributor D.

[0054] When a load is to be lowered, the piloting fluid entering the control device 1 through the pilot opening P is a part of the pressured fluid supplying the hydraulic motor

M.

[0055] The piloting fluid shall reach the piloting chamber 9 with such a piloting pressure as to exert an axial force on the auxiliary piston 13 which, in turn, will exert an axial force on the main piston 5.

[0056] It must be noted that the piloting chamber 9 is in fluid communication with the pilot opening P through piloting shutter means 10 and throttling means 11. It must also be noted that the auxiliary chamber 15 is in fluid communication with the first opening 3 (or with the external environment), thereby the pressure in the auxiliary chamber 15 is substantially equal to the pressure in the first opening 3. On a side of the auxiliary piston 13, the pressure in the auxiliary chamber 15 acts, and, on the other side, the pressure in the piloting chamber 9 acts. Furthermore, the pilot opening P is in fluid communication with the service opening 21 through the selector valve 19. [0057] The main piston 5 may be configured such to start moving in the axial opening direction by performing a pre-run without opening, in this initial pre-run step, the passage section of the cavity inside the valve body 2.

[0058] The piloting pressure is relatively high, thereby such pressure will be able to unlock the hydraulic parking brake 20 connected to the service opening 21.

[0059] A part of the piloting fluid flows through the throttling means 11 and reaches the piloting chamber 9 exerting a push action on the auxiliary piston 13 and closing the piloting shutter means 10 (in particular the shutter 17), whereby the main piston 5 will be further moved towards the opening by the piloting fluid which has flown through the throttling means 11.

[0060] The main piston 5 moves until it opens the passage section whereby the operative flow rate of the fluid will pass and start the descent of the load.

[0061] In order to interrupt lowering the load, the supply of the pressurised fluid is interrupted, whereby the pilot opening P no longer receives pressurised fluid. The piloting fluid which is in the valve body 2 will flow out passing through unidirectional means 12. The main piston 5 is moved towards the axial closing direction by actuating means 6 (spring), whose force is no longer contrasted by the auxiliary piston 13, closing the passage section and interrupting the connection between the first opening 3 and the second opening 4.

[0062] The control device 1 creates a control valve that, after the initial opening step, may further continue the opening step rather quickly. The control device 1 is substantially able to perform an actual control on a hydraulic actuator only during the first opening step of the actuator, while, in the time period following this first opening step - i.e., in a time period wherein a strict control is no longer required and the flow rate of the fluid can increase quickly -, the shutter opening can occur quickly thus reducing energy losses.

[0063] The auxiliary piston 13 may in fact serve as an additional piloting piston which allows to obtain a relatively high piloting ratio greater than 6:1, or greater than 8:1, or greater than 10:1. The piloting ratio may be in particular the ratio between the area of the section of the piloting piston 13 (or second sealing area, or section defined by second sealing means 14) and the annular area defined by the difference between the passage section controlled by the main piston 5 and the sealing area (or section defined by first sealing means 7). In the specific example shown, the piloting ratio is of about 13:1. [0064] The control device 1 may be used in particular for controlling the movement of a load. The piloting ratio is one of the parameters regulating the opening of the control device 1. In particular, the piloting pressure required to open the control device 1, and therefore to move a load, is a function of the piloting ratio, which will depend on the construction of the control device 1, of a calibration pressure, which will depend on the calibration of the control device 1, and of a pressure induced by the load, which will depend on the specific use.

[0065] The throttling means 11 (comprising in this case a throttling screw) enables to reduce the instability of the system. The unidirectional means 12 (comprising in this case a check valve), which creates a sort of bypass with respect to the throttling means 11, allows to cancel or, in any case, reduce considerably, the closing (or opening) delay, which would be generated due to the need of emptying (or filling) the volume of the piloting chamber 9. [0066] The auxiliary piston 13 substantially creates an additional piloting piston which guarantees a high calibration of the device. It is possible at the same time to open completely very quickly the device itself.

[0067] The auxiliary piston 13 further allows to obtain a stabilization effect of the device. As a matter of fact, in the control device 1 the forces acting on the main piston 5 are particularly high, as on one side of the main piston 5 the auxiliary piston 13 will be able to act, with a relatively high diameter, and on the other side the actuating means 6 will be able to act, with relatively very rigid elastic means. This will imply that the force of the oleodynamic flow will affect less the opening of the main piston 5.

Claims

1. Control device (1), comprising: a valve body (2) with at least one internal cavity for the passage of fluid, a first opening (3) for the passage of fluid, a second opening (4) for the passage of fluid, a pilot opening (P); a main piston (5) axially movable in said cavity with the possibility of assuming at least one closed position, in which the main piston (5) closes a passage section between said first opening (3) and said second opening (4), and at least one opening position, in which the main piston (5) opens said passage section; actuating means (6) arranged at a first end of said main piston (5) for exerting an axial force on said main piston (5); first sealing means (7) on said main piston (5) for defining a first sealing area between said second opening (4) and a second end of said main piston (5) opposite to said first end; a piloting piston (8) that is movable coaxially to said main piston (5) within a piloting chamber (9) inside said valve body (2); piloting shutter means (10) arranged to interact with said piloting piston (8) to control a passage of fluid between said pilot opening (P) and said piloting chamber (9); throttling means (11) arranged to generate a throttling between said pilot opening (P) and said piloting chamber (9); unidirectional means (12) arranged in parallel with respect to said throttling means (11); characterized by comprising: an auxiliary piston (13) that is movable coaxially to said main piston (5), a first end of said auxiliary piston (13) facing said second end of said main piston (5), a second end of said auxiliary piston (13) facing a first end of said pilot piston (8), said piloting chamber (9) being delimited at least in part by said second end of said auxiliary piston (13).

2. Device according to claim 1, comprising second sealing means (14) on said auxiliary piston (13) for defining a second sealing area greater than said first sealing area; said auxiliary piston (13) being arranged at least in part in an auxiliary chamber (15) axially comprised between said first sealing means (7) and said second sealing means (14).

3. Device according to claim 2, wherein said auxiliary chamber (15) is in fluid communication with said first opening (3), or with the external environment, in particular by means of a channel (16) obtained in said main piston (5).

4. Device according to claim 2 or 3, wherein said passage section has an area lower than said second sealing area and/or higher than said first sealing area.

5. Device according to any one of the preceding claims, wherein said first end of said auxiliary piston (13) is configured to interact in contact with said second end of said main piston (5).

6. Device according to any one of the preceding claims, wherein said second end of said auxiliary piston (13) is configured to interact in contact with said first end of said pilot piston (8).

7. Device according to any one of the preceding claims, wherein said first end of said auxiliary piston (13) has a straight cross section which is in contact with said second end of said main piston (5) and which is of smaller area than said first sealing area.

8. Device according to any one of the preceding claims, wherein said piloting shutter means (10) can selectively assume at least one open configuration, in which the piloting shutter means (10) opens said passage of fluid, and a closed configuration, in which the piloting shutter means (10) closes said passage of fluid and wherein the fluid passes from said pilot opening (P) to said piloting chamber (9) through said throttling means (11) to move said auxiliary piston (13).

9. Device according to any one of the preceding claims, wherein said actuating means (6) comprises elastic means arranged to push said main piston (5) towards said closed position.

10. Device according to any one of the preceding claims, wherein said piloting shutter means (10) comprises at least one longitudinal element, a shutter (17) and a spring, said longitudinal element being coupled to said valve body (2), for example by means of a screw coupling, said shutter (17) and said spring being arranged in said longitudinal element, said spring being configured to push said shutter (17) into a closed position in which the shutter (17) closes a hole which is obtained in said longitudinal element and which communicates with said piloting chamber (9), said piloting piston (8) being partly housed inside said hole.

11. Device according to any one of the preceding claims, wherein said throttling means (11) comprises a closing element coupled with said valve body (2) by means of a threaded connection which defines a passage of fluid, said closing element being provided with adjustment means arranged to regulate a screwing of said closing element and to consequently adjust the throttling means (11), said unidirectional means (12) comprising a check valve arranged in said closing element.

12. Working apparatus comprising a pump, a distributor (D) connected to said pump, a hydraulic motor (M) connected to said distributor (D) and a control device (1) connected to said hydraulic motor (M) and to said distributor (D) and made according to any one of the preceding claims.