Patent Description:
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.

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 <CIT> discloses a similar oleodynamic control device.

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.

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

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

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

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

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.

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

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

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

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

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.

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

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 <NUM>:<NUM>.

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 <NUM>: <NUM>.

The invention will be better understood and implemented with reference to the enclosed drawings which show non-limiting embodiments thereof, wherein:.

With reference to the aforesaid figures, an oleodynamic control device is referred to, on the whole, by <NUM>. The control device <NUM> may be used, in particular, for controlling an oleodynamic actuator. The control device <NUM> 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..

The control device <NUM> comprises a valve body <NUM> with at least one internal cavity for the passage of a fluid. The valve body <NUM> 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 <NUM> comprises at least one first opening <NUM>, or one first port, for the passage of an operative flow rate of an oleodynamic fluid (oil) and at least one second opening <NUM> or second port, for the passage of an operative flow rate of the oleodynamic fluid.

The valve body <NUM> comprises at least one pilot opening P, or pilot port, for the passage of a piloting flow rate that may be used to provide a piloting signal, as will be explained hereinafter.

The openings, or ports, arranged on the valve body <NUM> allow to connect the control device <NUM> to an oleodynamic circuit of a working apparatus (see <FIG>), as, in particular, a load lifting apparatus (such as a winch).

The first opening <NUM> and the second opening <NUM> 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 <NUM> may serve, e. g for lifting a load, as an entrance for the fluid into the cavity of the valve body <NUM> and the second opening <NUM> may serve as an exit for the fluid from the cavity of the valve body <NUM>, and vice versa for lowering a load.

The control device <NUM> comprises a main piston <NUM> axially movable in the cavity of the valve body <NUM>. The main piston <NUM> is movable with the possibility of assuming at least one closing position and at least one opening position. In the opening position the main piston <NUM> closes a passage section of the fluid through the cavity, where such passage section is arranged between the first opening <NUM> and the second opening <NUM>. In the opening position the main piston <NUM> opens the passage section to allow a flow. The passage section may in particular be defined between the shutter of the main piston <NUM> 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 <NUM>.

The control device <NUM> comprises actuating means <NUM> arranged at a first end of the main piston <NUM> to exert an axial force on the main piston <NUM>. Such actuating means <NUM> may in particular comprise elastic means arranged to push the main piston <NUM> towards the closing position. Elastic means may in particular comprise a spring.

The control device <NUM> comprises first sealing means <NUM> arranged on the main piston <NUM> to define a first sealing area. First sealing means <NUM> is defined between the second opening <NUM> and a second end of the main piston <NUM> opposite the aforesaid first end. First sealing means <NUM> may in particular comprise a sealing ring.

The control device <NUM> comprises a piloting piston <NUM> movable in the valve body <NUM>. The piloting piston <NUM> is movable coaxially with respect to the main piston <NUM>. The piloting piston <NUM> is movable within a piloting chamber <NUM> obtained inside the valve body <NUM> and connected to the pilot opening P.

The control device <NUM> comprises piloting shutter means <NUM> arranged to interact (in contact) with the piloting piston <NUM> to control a passage of a piloting fluid. Such passage is between the pilot opening P and the piloting chamber <NUM>.

Piloting shutter means <NUM> 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 <NUM> passing through throttling means <NUM> (as will be better explained hereinafter), so as to move an auxiliary piston, as will be better explained hereinafter.

The control device <NUM> comprises throttling means <NUM> arranged to generate a throttling (with a relative limited load loss) between the pilot opening P and the piloting chamber <NUM>.

The throttling means <NUM> may comprise, in particular, a closing element coupled with the valve body <NUM> 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.

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 <NUM>.

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.

The control device <NUM> comprises unidirectional means <NUM> arranged in parallel with respect to the throttling means <NUM>. The unidirectional means <NUM> may be configured, in particular as in these examples, to allow a flow of a piloting fluid from the piloting chamber <NUM> towards the pilot opening P. In other examples, not shown, the unidirectional means <NUM> may be configured to allow a reverse flow.

The unidirectional means <NUM> may in particular comprise a check valve arranged in the closing element of the throttling means <NUM>.

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

The control device <NUM> comprises an auxiliary piloting piston <NUM> that is movable in the valve body <NUM>. The auxiliary piloting piston <NUM> is movable coaxially with respect to the main piston <NUM> and/or coaxially with respect to the piloting piston <NUM>.

The auxiliary piston <NUM> is, axially comprised between the main piston <NUM> and the piloting piston <NUM>.

The auxiliary piston <NUM> has a first end facing the second end of the main piston <NUM>. The first end of the auxiliary piston <NUM> may in particular interact in contact with the second end of the main piston <NUM>.

The auxiliary piston <NUM> has a second end (for instance opposite to the first end) facing a first end of the piloting piston <NUM>. The piloting chamber <NUM> is at least partially delimited by the aforesaid second end of the auxiliary piston <NUM>.

The control device <NUM> may comprise in particular second sealing means <NUM> arranged on the auxiliary piston <NUM>. The second sealing means <NUM> may be in particular arranged to define a second sealing area. The second sealing means <NUM> may comprise in particular a sealing ring. In other examples the second sealing means <NUM> may comprise a sliding coupling, between the auxiliary piston <NUM> 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.

The passage section which is controlled by the main piston <NUM> may have, as in this example, an area lower than the second sealing area. The passage section which is controlled by the main piston <NUM> may have, as in this example, an area greater than the first sealing area.

The auxiliary piston <NUM> may be in particular at least partially arranged in an auxiliary chamber <NUM> axially comprised between the first sealing means <NUM> and the second sealing means <NUM>. The second sealing means <NUM> may be in particular configured in such a way as to separate the piloting chamber <NUM> from the auxiliary chamber <NUM>. The auxiliary chamber <NUM> may be, as in this example, in fluid communication with the first opening <NUM>, or with the external environment. The control device <NUM> may in particular comprise, a channel <NUM> configured to fluidically connect the auxiliary chamber <NUM> with the first opening <NUM>, or with the external environment. The connection channel <NUM> between the auxiliary chamber <NUM> and the first opening <NUM> may be obtained, in particular, inside the main piston <NUM>.

The first end of the auxiliary piston <NUM> may be configured, in particular, to interact in contact with the second end of the main piston <NUM>.

The first end of the auxiliary piston <NUM> may have, as in this example, a straight cross section with an area lower than the first sealing area.

The first end of the auxiliary piston <NUM> may be configured, in particular, to interact in contact with the first end of the piloting piston <NUM>.

The piloting shutter means <NUM> may in particular comprises at least one longitudinal element. The piloting shutter means <NUM> may in particular comprise at least one shutter <NUM>. The piloting shutter means <NUM> may in particular comprise at least one spring. The longitudinal element may be coupled, in particular, to a valve body <NUM>, such as by a screw coupling. The shutter <NUM> may be arranged, in particular, inside the longitudinal element. The spring may be arranged, in particular, inside the longitudinal element.

The aforesaid spring may be configured, as in this example, to push the shutter <NUM> to a closing position wherein the shutter <NUM> closes a hole obtained in the longitudinal element. The hole may be in particular communicating with the piloting chamber <NUM>. The piloting piston <NUM> may be, as in this specific example, partially housed in the hole.

The control device <NUM> may comprise, in particular, a brake release valve <NUM> with a selector valve <NUM> which may be configured, in particular, to allow disabling a hydraulic parking brake <NUM> operatively associated to a hydraulic motor M (see <FIG>). The valve device <NUM> may comprise, in particular, a service opening <NUM>, or service door, which may be, as in this example, for connecting the brake release valve <NUM> with the hydraulic parking brake <NUM>.

In <FIG> 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 <NUM> described above. The control device <NUM> has been represented by a long-dashed and short-dashed line.

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.

The control device <NUM> 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 <NUM> 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 <NUM>) which is normally present in case a hydraulic motor is used.

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.

When a load is to be lowered, the piloting fluid entering the control device <NUM> through the pilot opening P is a part of the pressured fluid supplying the hydraulic motor M.

The piloting fluid shall reach the piloting chamber <NUM> with such a piloting pressure as to exert an axial force on the auxiliary piston <NUM> which, in turn, will exert an axial force on the main piston <NUM>.

It must be noted that the piloting chamber <NUM> is in fluid communication with the pilot opening P through piloting shutter means <NUM> and throttling means <NUM>. It must also be noted that the auxiliary chamber <NUM> is in fluid communication with the first opening <NUM> (or with the external environment), thereby the pressure in the auxiliary chamber <NUM> is substantially equal to the pressure in the first opening <NUM>. On a side of the auxiliary piston <NUM>, the pressure in the auxiliary chamber <NUM> acts, and, on the other side, the pressure in the piloting chamber <NUM> acts. Furthermore, the pilot opening P is in fluid communication with the service opening <NUM> through the selector valve <NUM>.

The main piston <NUM> 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 <NUM>.

The piloting pressure is relatively high, thereby such pressure will be able to unlock the hydraulic parking brake <NUM> connected to the service opening <NUM>.

A part of the piloting fluid flows through the throttling means <NUM> and reaches the piloting chamber <NUM> exerting a push action on the auxiliary piston <NUM> and closing the piloting shutter means <NUM> (in particular the shutter <NUM>), whereby the main piston <NUM> will be further moved towards the opening by the piloting fluid which has flown through the throttling means <NUM>.

The main piston <NUM> moves until it opens the passage section whereby the operative flow rate of the fluid will pass and start the descent of the load.

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 <NUM> will flow out passing through unidirectional means <NUM>. The main piston <NUM> is moved towards the axial closing direction by actuating means <NUM> (spring), whose force is no longer contrasted by the auxiliary piston <NUM>, closing the passage section and interrupting the connection between the first opening <NUM> and the second opening <NUM>.

The control device <NUM> creates a control valve that, after the initial opening step, may further continue the opening step rather quickly. The control device <NUM> 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.

The auxiliary piston <NUM> may in fact serve as an additional piloting piston which allows to obtain a relatively high piloting ratio greater than <NUM>:<NUM>, or greater than <NUM>:<NUM>, or greater than <NUM>: <NUM>. The piloting ratio may be in particular the ratio between the area of the section of the piloting piston <NUM> (or second sealing area, or section defined by second sealing means <NUM>) and the annular area defined by the difference between the passage section controlled by the main piston <NUM> and the sealing area (or section defined by first sealing means <NUM>). In the specific example shown, the piloting ratio is of about <NUM>:<NUM>.

The control device <NUM> 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 <NUM>. In particular, the piloting pressure required to open the control device <NUM>, and therefore to move a load, is a function of the piloting ratio, which will depend on the construction of the control device <NUM>, of a calibration pressure, which will depend on the calibration of the control device <NUM>, and of a pressure induced by the load, which will depend on the specific use.

The throttling means <NUM> (comprising in this case a throttling screw) enables to reduce the instability of the system. The unidirectional means <NUM> (comprising in this case a check valve), which creates a sort of bypass with respect to the throttling means <NUM>, 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 <NUM>.

The auxiliary piston <NUM> 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.

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