Hydraulic control device

Abstract

An oil pressure control device is disclosed having a valve body, a main piston axially movable in the valve body, an actuating member operating on a first end of the main piston, a pilot piston movable within the valve body within a pilot chamber, a pilot shutter for controlling the passage of fluid in the pilot chamber, a restriction member for creating a restriction toward the pilot chamber, a one-way member configured in parallel with the restriction member to enable flow from the pilot chamber, a pilot assist piston between the main piston and the pilot piston, wherein the pilot assist piston has a larger sealing diameter, thereby inducing a larger pilot ratio.

Description

TECHNICAL FIELD

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

[0002] The present invention can be used in particular, but 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 load lifting equipment, such as winches. In any case, the present invention can be used for controlling different types of oil pressure actuators, such as hydraulic cylinders that can be used in particular in earthmoving machines.

[0003] The present invention relates in particular to an oil pressure control device according to the preamble of claim 1, wherein the throttling member increases the operating stability and the one-way member reduces the actuation delay caused by the throttling member. The patent publication EP 2631517 A1 discloses a similar oil pressure control device. BACKGROUND

[0004] However, this known control device is less suitable in certain cases, in particular when a valve device is required that is characterized by a high degree of accuracy, i.e. a device that can be configured to activate the flow rate of the operating fluid by starting at a higher pressure to open the shielding body and at the same time is able to quickly reach the desired shielding body opening position, to counteract small resistances and in turn reduce the energy consumption. This can happen, for example, when the oil pressure actuator to be controlled is a hydraulic motor.

[0005] It is also desirable to further increase the operating stability of the control device of the prior art. SUMMARY

[0006] It is an object of the present invention to overcome one or more of the aforementioned limitations and drawbacks of the prior art.

[0007] It is an object to provide an oil pressure control device that can replace those of the prior art.

[0008] It is an advantage to be able to start opening the flow control shielding body at a higher pressure.

[0009] It is an advantage to provide a control device that is able to switch from the initial closed position of the oil pressure flow to the desired open position of the oil pressure flow in a shorter time.

[0010] It is an advantage to implement an oil pressure control device with a lower energy consumption.

[0011] It is an advantage to form a control device that is able to reach the desired valve opening position at a lower working pressure.

[0012] It is an advantage to provide an oil pressure control device with a relatively high operating stability.

[0013] The advantage is to be able to achieve a precise, stable and reliable control of the oil pressure actuators, in particular of the hydraulic motors.

[0014] The advantage is to be able to control the actuators so as to avoid or reduce the delay between the moment in which the operator actuates the command and the moment in which the movable element of the actuator starts to displace, in particular when the oil pressure fluid is more viscous, for example in winter.

[0015] These and other objects and advantages are also achieved by the control device according to one or more of the claims set out hereinafter.

[0016] In one embodiment, the oil pressure control device comprises: a valve body having an internal cavity and a command opening; a main piston axially movable in the cavity of the valve body; an actuation element configured at a first end of the main piston; a pilot piston movable inside the valve body in a pilot chamber; a shutter for controlling the passage of fluid between the command opening and the pilot chamber; a throttle for creating a throttle between the command opening and the pilot chamber; a check element configured in parallel with respect to the throttle; an auxiliary pilot piston having a first end facing a second end of the main piston and having a second end facing a first end of the pilot piston, wherein at least one sealing diameter of the auxiliary pilot piston is configured so as to obtain a structure with a relatively high pilot ratio, for example a pilot ratio greater than 8:1.

[0017] In one embodiment, the oil pressure control device comprises a valve body, a main piston axially movable in the valve body, an actuation element operating on a first end of the main piston, a first sealing element defining a first sealing area in the main piston, a pilot piston movable inside an internal pilot chamber for controlling the passage of fluid into the pilot chamber, a throttle creating a throttle towards the pilot chamber, a check element configured in parallel with respect to the throttle, an auxiliary pilot piston configured between the main piston and the pilot piston, a second sealing element defining a second sealing area on the auxiliary pilot piston. The second sealing area is configured so that the pilot ratio is relatively large, for example so that the pilot ratio is greater than 8:1. BRIEF DESCRIPTION OF DRAWINGS

[0018] The present application will be better understood and implemented with reference to the attached drawings, which show non-limiting embodiments of the present application, in which:

[0019] Figure 1 is a longitudinal section of an embodiment of the control device made according to the present application;

[0020] Figure 2 is a longitudinal section of the device of Figure 1 is a longitudinal section of the device of Figure 1 is a longitudinal section of the device of

[0021] Figure 3 enlarged detail view of Figure 2 ;

[0022] Figure 4 is a hydraulic schematic of a working equipment comprising Figure 1 a control device. DETAILED DESCRIPTION

[0023] With reference to the preceding figures, an oil pressure control device is indicated in general by 1. In particular, the control device 1 can be used for controlling an oil pressure actuator. In particular, the control device 1 can be used in a hydraulic circuit for controlling a hydraulic motor M, for example a hydraulic motor employed in a load lifting equipment, such as a winch or the like. In particular, the hydraulic motor M can have two rotation directions, have a fixed or variable displacement, and the like.

[0024] In particular, the control device 1 can comprise a valve body 2 having at least one internal cavity for passage of fluid. In particular, the valve body 2 can comprise a block made in one piece, for example in the embodiment shown, or in assembled pieces. In particular, the valve body 2 can comprise at least one first opening 3 or first gate for passage of an operating flow of oil pressure fluid (oil) and at least one second opening 4 or second gate for passage of an operating flow of oil pressure fluid.

[0025] In particular, the valve body 2 can comprise at least one pilot opening P or pilot gate for passage of a pilot flow, which can be used to provide a pilot signal, as will be set out hereinafter.

[0026] The openings or gates configured on the valve body 2 are able to connect the control device 1 to an oil pressure circuit of a working equipment, such as in particular a load lifting equipment, for example a winch (see Figure 4 ).

[0027] In particular, the first opening 3 and the second opening 4 can be configured for passage of an operating flow of fluid required to supply a hydraulic actuator. In use, for example to lift a load, the first opening 3 can be used as an inlet of fluid into the cavity of the valve body 2, and vice versa, to lower the load, the second opening 4 can be used as an outlet of fluid from the cavity of the valve body 2.

[0028] In particular, the control device 1 can comprise a main piston 5 axially movable in the cavity of the valve body 2. The main piston 5 is movable, in particular in such a way as to be able to have at least one closed position and at least one open position. In the open position, the main piston 5 closes a passage section of the fluid through the cavity, wherein the passage section is configured between the first opening 3 and the second opening 4. In the open position, the main piston 5 opens the passage section to enable the flow. In particular, the passage section can be defined between a masking body of the main piston 5 and an annular seat of a movable body C configured in the cavity. In particular, a spring M can be configured to push the movable body C (axially slidingly) towards the masking of the main piston 5.

[0029] In particular, the control device 1 can comprise an actuation piece 6 configured at a first end of the main piston 5 to exert an axial force on the main piston 5. In particular, such an actuation piece 6 can comprise an elastic piece configured to push the main piston 5 towards the closed position. In particular, the elastic piece can comprise a spring.

[0030] In particular, the control device 1 can comprise a first seal 7 configured on the main piston 5 to define a first sealing area. In particular, the first seal 7 can be defined between the second opening 4 and a second end of the main piston 5 opposite the aforementioned first end. In particular, the first seal 7 can comprise a sealing ring.

[0031] In particular, the control device 1 can comprise a guide piston 8 movable in the valve body 2. In particular, the guide piston 8 can be movable in a coaxial manner with respect to the main piston 5. In particular, the guide piston 8 can be movable within a guide chamber 9 present inside the valve body 2 and connected to a guide opening P.

[0032] In particular, the control device 1 can comprise a guide masking 10 configured to interact (contact) with the guide piston 8 to control the passage of a guide fluid. The passage is located between the guide opening P and the guide chamber 9.

[0033] In particular, the guide masking 10 can be configured so as to selectively have at least one open configuration, in which the guide masking opens the aforementioned passage of the guide fluid, and a closed configuration, in which the guide masking closes the aforementioned passage of the guide fluid. In the closed configuration, the guide fluid will flow from the guide opening P to the guide chamber 9 through a throttling piece 11 (as will be better illustrated hereinafter), to move an auxiliary piston, as will be better illustrated hereinafter.

[0034] In particular, the control device 1 can comprise a throttling piece 11 configured to create a throttling (with a relatively limited load loss) between the guide opening P and the guide chamber 9.

[0035] In particular, the throttling member 11 can comprise a closing element coupled with the valve body 2 by means of a threaded connection. The threaded connection defines a passage of the pilot fluid that induces throttling, in particular a helical passage.

[0036] In particular, the closing element can be provided with an adjustment element configured to adjust the screwing of the closing element itself, thus adjusting the degree of throttling provided by the throttling member 11, i.e. the degree of load loss in throttling.

[0037] In other embodiments, not shown, the throttling member can comprise other types of throttling, for example a throttling produced by a fixed screw, or a throttling produced by several (conical or cylindrical) coaxial elements that partially fit into each other to define an orifice of adjustable size, or a throttling produced by other means.

[0038] In particular, the control device 1 can comprise a one-way member 12 configured in parallel with respect to the throttling member 11. In particular, as in these embodiments, the one-way member 12 can be configured so that the pilot fluid flows from the pilot chamber 9 towards the pilot opening P. In other embodiments, not shown, the one-way member 12 can be configured to enable a reverse flow.

[0039] In particular, the one-way member 12 can comprise a check valve configured in the closing element of the throttling member 11.

[0040] The one-way member 12 enables the quick filling and emptying of the pilot chamber 9. For example, when the operator starts, for example, a pilot operation, for example for lifting a load, the main piston 5 opens the aforementioned passage section configured between the first opening 3 and the second opening 4, whereby the pilot chamber 9 is quickly filled. When the operator ends, for example, a pilot operation, the main piston 5 blocks again the passage section between the first opening 3 and the second opening 4, whereby the pilot chamber 9 is quickly emptied. The one-way member 12 further enables the safe flow of the pilot fluid towards the pilot opening P when the pressure in the pilot chamber 9 overcomes a predetermined value.

[0041] In particular, the control device 1 can comprise an auxiliary pilot piston 13 movable in the valve body 2. In particular, the auxiliary pilot piston 13 can move in a coaxial manner with respect to the main piston 5 and / or in a coaxial manner with respect to the pilot piston 8.

[0042] In particular, the auxiliary piston 13 can be axially comprised between the main piston 5 and the pilot piston 8.

[0043] In particular, the auxiliary piston 13 can have a first end facing the second end of the main piston 5. In particular, the first end of the auxiliary piston 13 can interact in contact with the second end of the main piston 5.

[0044] In particular, the auxiliary piston 13 can have a second end facing the first end of the pilot piston 8 (for example opposite the first end). In particular, the pilot chamber 9 can be at least partially delimited by the aforesaid second end of the auxiliary piston 13.

[0045] In particular, the control device 1 can comprise a second seal 14 configured on the auxiliary piston 13. In particular, the second seal 14 can be configured to define a second sealing region. In particular, the second seal 14 can comprise a sealing ring. In other embodiments, the second seal 14 can comprise a sliding coupling between the auxiliary piston 13 and the cavity housing the piston, with a gap to obtain a proper sealing effect, in particular suitable to implement the sealing effect of the gas discharge or release in any case. As in this embodiment, the second sealing region can be greater than the first sealing region.

[0046] As in this embodiment, the area of the passage section controlled by the main piston 5 can be smaller than the second sealing region. As in this embodiment, the area of the passage section controlled by the main piston 5 can be greater than the first sealing region.

[0047] In particular, the auxiliary piston 13 can be at least partially configured in an auxiliary chamber 15 axially comprised between the first seal 7 and the second seal 14. In particular, the second seal 14 can be configured so as to separate the pilot chamber 9 from the auxiliary chamber 15. As in this embodiment, the auxiliary chamber 15 can be in fluid communication with the first opening 3 or with the external environment. In particular, the control device 1 can comprise a channel 16 configured to fluidly connect the auxiliary chamber 15 with the first opening 3 or with the external environment. In particular, the connection channel 16 between the auxiliary chamber 15 and the first opening 3 can be obtained inside the main piston 5.

[0048] In particular, the first end of the auxiliary piston 13 can be configured to interact in contact with the second end of the main piston 5.

[0049] As in this embodiment, the first end of the auxiliary piston 13 can have a straight section with an area smaller than the first sealing region.

[0050] In particular, the first end of the auxiliary piston 13 can be configured to interact in contact with the first end of the pilot piston 8.

[0051] In particular, the pilot shield 10 can comprise at least one longitudinal element. In particular, the pilot shield 10 can comprise at least one shield body 17. In particular, the pilot shield 10 can comprise at least one spring. In particular, the longitudinal element can be coupled to the valve body 2, for example by means of a screw coupling. In particular, the shield body 17 can be configured inside the longitudinal element. In particular, the spring can be configured inside the longitudinal element.

[0052] As in this embodiment, the aforementioned spring can be configured to push the shutter 17 into the closed position, in which it closes the hole present in the longitudinal element. In particular, the hole can communicate with the pilot chamber 9. As in this specific embodiment, the pilot piston 8 can be partially housed in the hole.

[0053] In particular, the control device 1 can comprise a brake release valve 18 with a selection valve 19, which can be configured in particular so as to enable the disabling of the hydraulic parking brake 20 operatively associated with the hydraulic motor M (see Figure 4 ). In particular, the valve device 1 can comprise a service opening 21 or service door, which, as in this embodiment, can be used to connect the brake release valve 18 with the hydraulic parking brake 20.

[0054] In Figure 4 , a schematic view of a work device comprising a distributor D and a hydraulic motor M connected to the distributor D is shown. The work device also comprises the control device 1 described above. The control device 1 is indicated by long and short dashed lines.

[0055] In particular, the work device can comprise a (type known and not shown) pump connected to the distributor D. In particular, the hydraulic motor M can comprise a hydraulic motor with two rotation directions. In particular, the work device can comprise a load lifting device, for example a winch, the pulling member of which comprises a hydraulic motor.

[0056] As stated, the control device 1 can be used to control a hydraulic motor M (however it can be used for other actuators, for example excavator hydraulic cylinders). In particular, when it is necessary to use a high-precision control valve, the control device 1 can be used to be able to safely open the control valve and unlock the brakes (for example the hydraulic parking brake 20) normally present in the case of use of the hydraulic motor.

[0057] In use, the operator can start a piloting operation, in particular on the distributor D, by means of a command device (not shown, for example of the type known).

[0058] When the load is to be lowered, the piloting fluid that enters the control device 1 through the piloting opening P is part of the pressurized fluid that supplies the hydraulic motor M.

[0059] The piloting fluid reaches the pilot chamber 9 at this piloting pressure to exert an axial force on the auxiliary piston 13, which in turn exerts an axial force on the main piston 5.

[0060] It has to be noted that the pilot chamber 9 is in fluid communication with the pilot opening P through the pilot shutter 10 and the restriction 11. It has also to be noted that the auxiliary chamber 15 is in fluid communication with the first opening 3 (or with the outside environment), whereby the pressure in the auxiliary chamber 15 is approximately equal to the pressure in the first opening 3. The pressure in the auxiliary chamber 15 acts on one side of the auxiliary piston 13 and the pressure in the pilot chamber 9 acts on the other side. Furthermore, the pilot opening P is in fluid communication with the service opening 21 through the selector valve 19.

[0061] The main piston 5 can be configured such that by performing a pre-run without opening the passage section of the cavity inside the valve body 2 at this initial pre-run step the movement in axial opening direction is started.

[0062] The pilot pressure is higher, whereby this pressure will be able to unlock the hydraulic emergency brake 20 connected to the service opening 21.

[0063] A part of the pilot fluid flows through the restriction 11 and reaches the pilot chamber 9, exerts a pushing action on the auxiliary piston 13 and closes the pilot shutter 10 (in particular the shutter body 17), whereby the main piston 5 is further moved towards the opening by the pilot fluid that has already flown through the restriction 11.

[0064] The main piston 5 moves until it opens the passage section, whereby the operating flow of fluid will pass and the drop of load starts.

[0065] To interrupt the drop of load, the supply of pressurized fluid is interrupted, whereby the pilot opening P does not receive pressurized fluid anymore. The pilot fluid in the valve body 2 will flow out through the one-way 12. The main piston 5 is moved by the actuating element 6 (spring) towards the axial closing direction, the force of which is not opposed by the auxiliary piston 13 anymore, closing the passage section and interrupting the connection between the first opening 3 and the second opening 4.

[0066] The control device 1 forms a control valve that can continue the opening step quite fast after the initial opening step. The control device 1 is essentially able to perform an actual control of the hydraulic actuator only during the first opening step of the actuator, whereas after this first opening step, in a time period in which no strict control is needed anymore and the flow of fluid can be increased quickly, the shutter can be opened quickly, reducing the energy loss.

[0067] The auxiliary piston 13 can in fact act as an additional pilot piston, which enables a relatively high pilot ratio to be obtained, greater than 6:1, or greater than 8:1, or greater than 10:1. In particular, the pilot ratio can be the ratio between the annular area defined by the difference between the area of the section of the pilot piston 13 (or the second sealing area, or the section defined by the second seal 14) and the passage section and the sealing area controlled by the main piston 5 (or the section defined by the first seal 7). In the specific embodiment shown, the pilot ratio is about 13:1.

[0068] In particular, the control device 1 can be used to control the movement of a load. The pilot ratio is one of the parameters that regulates the opening of the control device 1. In particular, the pilot pressure required to open the control device 1 and thus move the load is a function of the pilot ratio, which is determined by the structure of the control device 1, of the calibration pressure, which is determined by the calibration of the control device 1, and of the pressure caused by the load, which is determined by the specific use.

[0069] The throttle 11 (in this case comprising a throttle screw) enables the instability of the system to be reduced. The non-return 12 (in this case comprising a check valve) forms a kind of bypass with respect to the throttle 11, which enables the closing (or opening) delay that can arise due to the need to empty (or fill) the volume of the pilot chamber 9 to be eliminated or in any case significantly reduced.

[0070] The auxiliary piston 13 substantially forms an additional pilot piston, which ensures a high calibration of the device. At the same time, the device itself can be opened completely very quickly.

[0071] The auxiliary piston 13 also enables a stabilising effect of the device to be obtained. In fact, the force acting on the main piston 5 in the control device 1 is particularly great, since the auxiliary piston 13 will be able to act on one side of the main piston 5 with a greater diameter, and the actuator 6 will be able to act on the other side with a relatively very rigid elastic element. This will mean that the force of the flow of oil pressure will have less influence on the opening of the main piston 5.

Claims

1. Control device (1) comprising: - a valve body (2) having at least one internal cavity for passage of a fluid, a first opening (3) for passage of a fluid, a second opening (4) for passage of a fluid, a pilot opening (P); - a main piston (5) axially movable in said cavity, able to have at least one closed position in which it closes a passage section between said first opening (3) and said second opening (4) and at least one open position in which it opens said passage section; - an actuation element (6) configured at a first end of said main piston (5) for exerting an axial force on said main piston (5); - a first seal (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 said first end; - a pilot piston (8) movable inside said valve body (2) within a pilot chamber (9) in a coaxial manner with said main piston (5); - a pilot shutter (10) configured to interact with said pilot piston (8) to control the passage of a fluid between said pilot opening (P) and said pilot chamber (9); - a throttling element (11) configured to create a throttling between said pilot opening (P) and said pilot chamber (9); - a one-way element (12) configured in parallel with respect to said throttling element (11); characterized by comprising: - an auxiliary piston (13) movable in a coaxial manner with 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 pilot chamber (9) being at least partially delimited by said second end of said auxiliary piston (13), said auxiliary piston (13) being able to act as an additional pilot piston able to achieve a pilot ratio greater than 6:

1.

2. The control device (1) according to claim 1, characterized in that comprising: a second seal (14) on said auxiliary piston (13) for defining a second sealing area greater than said first sealing area; said auxiliary piston (13) being at least partially configured in an auxiliary chamber (15) axially comprised between said first seal (7) and said second seal (14).

3. The control device (1) according to claim 2, characterized in that said auxiliary chamber (15) being in fluid communication with said first opening (3) or with the external environment.

4. The control device (1) according to claim 3, characterized in that said auxiliary chamber (15) being in fluid communication with said first opening (3) or with the external environment by means of a passage (16) present in said main piston (5).

5. The control device (1) according to any one of claims 2-4, characterized in that, the area of said passage section is smaller than said second sealing area and / or greater than said first sealing area.

6. The control device (1) according to any one of claims 2-4, characterized in that said first end of said auxiliary piston (13) is configured to interact in contact with said second end of said main piston (5).

7. The control device (1) according to any one of claims 2-4, characterized in that Said second end of said auxiliary piston (13) is configured to interact in contact with said first end of said pilot piston (8).

8. The control device (1) according to any one of claims 2-4, characterized in that Said first end of said auxiliary piston (13) has a straight section which is in contact with said second end of said main piston (5) and whose area is smaller than said first sealing area.

9. The control device (1) according to any one of claims 2-4, characterized in that, Said pilot shutter (10) can selectively have at least one open configuration, in which it opens the passage of said fluid, and a closed configuration, in which it closes the passage of said fluid, and wherein said fluid passes from said pilot opening (P) to said pilot chamber (9) through said throttle (11) to move said auxiliary piston (13).

10. The control device (1) according to any one of claims 2-4, characterized in that, Said actuation member (6) comprises an elastic member configured to push said main piston (5) towards said closed position.

11. The control device (1) according to any one of claims 2-4, characterized in that Said pilot shutter (10) comprises at least one longitudinal element coupled to said valve body (2), a shutter body (17) and a spring, said shutter body (17) and said spring being configured inside said longitudinal element, said spring being configured to push said shutter body (17) into a closed position in which it closes an aperture present in said longitudinal element and communicating with said pilot chamber (9), said pilot piston (8) being partially housed inside said aperture.

12. The control device (1) according to claim 11, characterized in that Said longitudinal element is coupled to said valve body (2) by means of a screw coupling.

13. The control device (1) according to any one of claims 2-4, characterized in that, Said throttle (11) comprises a closing element coupled to said valve body (2) by means of a threaded connection defining the passage of the fluid, said closing element being provided with an adjustment member configured to adjust the screwing of said closing element and therefore to adjust said throttle (11), said one-way member (12) comprising a check valve configured in said closing element.

14. Work equipment comprising a pump, a distributor (D) connected to said pump, a hydraulic motor (M) connected to said distributor (D), and a control device (1) according to any one of the preceding claims connected to said hydraulic motor (M) and to said distributor (D).

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