US-12618422-B2 - Hydraulic distributor with compensation device for directional valves

US12618422B2US 12618422 B2US12618422 B2US 12618422B2US-12618422-B2

Abstract

An open-center valve device for operating machines includes: a first section and a second section, a high-pressure line configured in such a way as to be connected to a pump to supply an operating fluid flow rate to the sections, and a discharge line configured to be connected to an outlet of the operating fluid. Each of the sections includes a spool control element, configured in such a way as to send the fluid flow rate to the respective work ports. The valve device further includes one or more free flow segments, a series duct configured in such a way that, upon a movement from the neutral position of one of the control elements for operating one of the actuators, a return flow rate from a respective work port is supplied to a subsequent control element, progressively closing the respective free flow passage.

Inventors

Matteo TALAMI
Guido DENTI
Mattia SCOLARI

Assignees

WALVOIL S.P.A.

Dates

Publication Date: 20260505
Application Date: 20241010

Claims (9)

1 . An open-center valve device for operating machines comprising: a first section and a second section, the sections being configured to be connected to respective pairs of work ports to operate a respective actuator of the operating machine, a high-pressure line configured in such a way as to be connected to a pump to supply a flow rate of an operating fluid to the sections, and a discharge line configured to be connected to an outlet for the operating fluid, each of the sections comprising a spool control element, configured in such a way as to send the flow rate to the respective work ports, the valve device further comprising: one or more free flow segments configured in such a way as to define a free flow line connecting in successive sequence each of the spool control elements, each of the spool control elements including a free-circulation passage configured in such a way that, when all the spool control elements are in a neutral position, the high-pressure line is connected to the discharge line without sending the flow rate to the work ports, a series duct configured in such a way that, upon a movement from the neutral position of one of the spool control elements for operating one of the actuators, a return flow rate from a respective use is supplied to a subsequent spool control element, progressively closing the respective free flow passage, the spool control elements comprising respective return passages configured to receive the return flow rate, respective non-return valves being provided, inserted inside respective spool control elements, downstream of the return passages of the spool control elements and upstream of the series duct, wherein at least one of the spool control elements comprises at least one bypass passage, the spool control elements being configured in such a way that, when a spool control element is in the neutral position, the bypass passage is closed and, when the spool control element is moved from the neutral position to operate the respective actuator, the spool control element progressively puts the bypass passage into communication with the outlet via the discharge line or a low-pressure line directly connected to the outlet, wherein each of the first and second sections comprise a return line configured in such a way that, when one of the spool control elements is moved from the neutral position to operate the respective actuator, the return flow rate from a driven actuator is fed to the respective return passage, and wherein the valve device further comprises a bypass duct, the bypass duct being external to the spool control element and being arranged as a bypass to the return line in such a way as to bring the return flow rate to the bypass passage in parallel with the return passages.
2 . A hydraulic system comprising a pump and a valve device according to claim 1 .
3 . An open-center valve device for operating machines comprising: a first section and a second section, the sections being configured to be connected to respective pairs of work ports to operate a respective actuator of the operating machine, a high-pressure line configured in such a way as to be connected to a pump to supply a flow rate of an operating fluid to the sections, and a discharge line configured to be connected to an outlet for the operating fluid, each of the sections comprising a spool control element, configured in such a way as to send the flow rate to the respective work ports, the valve device further comprising: one or more free flow segments configured in such a way as to define a free flow line connecting in successive sequence each of the spool control elements, each of the spool control elements including a free-circulation passage configured in such a way that, when all the spool control elements are in a neutral position, the high-pressure line is connected to the discharge line without sending the flow rate to the work ports, a series duct configured in such a way that, upon a movement from the neutral position of one of the spool control elements for operating one of the actuators, a return flow rate from a respective use is supplied to a subsequent spool control element, progressively closing the respective free flow passage, the spool control elements comprising respective return passages configured to receive the return flow rate, respective non-return valves being provided downstream of the return passages of the spool control elements and upstream of the series duct, wherein at least one of the spool control elements comprises at least one bypass passage, the spool control elements being configured in such a way that, when a spool control element is in the neutral position, the bypass passage is closed and, when the spool control element is moved from the neutral position to operate the respective actuator, the spool control element progressively puts the bypass passage into communication with the outlet via the discharge line or a low-pressure line directly connected to the outlet, wherein the sections comprise a return line configured in such a way that, when one of the spool control elements is moved from the neutral position to operate the respective actuator, the return flow rate from a driven actuator is fed to the respective return passage, and wherein the valve device further comprises a bypass duct, the bypass duct being arranged as a bypass to the return line in such a way as to bring the return flow rate to the bypass passage in parallel with the return passages and wherein the valve device further comprises a maximum pressure valve arranged along the bypass duct.
4 . An open-center valve device for operating machines comprising: a first section and a second section, the sections being configured to be connected to respective pairs of work ports to operate a respective actuator of the operating machine, a high-pressure line configured in such a way as to be connected to a pump to supply a flow rate of an operating fluid to the sections, and a discharge line configured to be connected to an outlet for the operating fluid, each of the sections comprising a spool control element, configured in such a way as to send the flow rate to the respective work ports, the valve device further comprising: one or more free flow segments configured in such a way as to define a free flow line connecting in successive sequence each of the spool control elements, each of the spool control elements including a free-circulation passage configured in such a way that, when all the spool control elements are in a neutral position, the high-pressure line is connected to the discharge line without sending the flow rate to the work ports, a series duct configured in such a way that, upon a movement from the neutral position of one of the spool control elements for operating one of the actuators, a return flow rate from a respective use is supplied to a subsequent spool control element, progressively closing the respective free flow passage, the spool control elements comprising respective return passages configured to receive the return flow rate, respective non-return valves being provided downstream of the return passages of the spool control elements and upstream of the series duct, wherein at least one of the spool control elements comprises at least one bypass passage, the spool control element being configured in such a way that, when the spool control element is in the neutral position, the bypass passage is closed and, when the spool control element is moved from the neutral position to operate the respective actuator, the spool control element progressively puts the bypass passage into communication with the outlet via the discharge line or a low-pressure line directly connected to the outlet, and wherein the valve device further comprises a two-way sequence slide valve through which the return flow rate is discharged.
5 . The valve device according to claim 4 , wherein the sequence slide valve is formed outside the spool control element.
6 . The valve device according to claim 4 , wherein the slide valve is normally closed and defines respective opposite ends, a pressure signal taken from a reduced pressure line acting on a first end, the reduced pressure being lower than the pressure of the high-pressure line, and a spring and a decoupled reduced pressure, which is decoupled by a throttle with respect to the pressure existing on the first end of the slide valve, acting on a second end, opposite to the first end.
7 . The valve device according to claim 6 , wherein the second connected end is connected to the bypass passage through an additional duct.
8 . The valve device according to claim 6 , wherein the reduced pressure line is configured to pilot respective spools of the spool control elements.
9 . The valve device according to claim 4 , wherein the slide valve defines respective opposite ends, a pressure existing in a duct derived from the return passage upstream of the non-return valve acting on a first end and a spring and a pressure, which is decoupled by a throttle with respect to the pressure existing on the first end of the slide valve, acting on a second end, opposite to the first end.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims benefit of Italian Patent Application No. 102023000021090, filed Oct. 10, 2023, the entire contents of which are incorporated herein as if fully set forth. FIELD OF APPLICATION The present invention relates to a valve device for an operating machine and a hydraulic system comprising the same. TECHNOLOGICAL BACKGROUND A typical example of an operating machine comprises a boom crane, a bucket, a hydraulic cylinder of the boom crane configured to operate the boom crane, a hydraulic cylinder of the bucket configured to operate the bucket, and one or more auxiliary actuators configured to operate auxiliary attachments. The respective hydraulic cylinders are operated by respective sections of a control valve present in the hydraulic circuit of the operating machine. For example, a first section can be configured to control the lengthening and shortening of the boom crane cylinder, a second section of the control valve configured to control the lengthening and shortening of the bucket cylinder, and a third section of the control valve configured to operate the auxiliary actuator. Typically, such sections are provided with relative spools and when the spool of the first valve section is not operated, the hydraulic oil sent from the pump passes through the inside of the spool itself and is supplied to the second section of the valve and, through the spool of the latter, to the subsequent sections. This constructive solution of the valve is referred to in the jargon as ‘free circulation LC’ passage. When the spool of the first control section is operated, the hydraulic oil returns from the cylinder boom crane of the first control device passing back from the first control section and is used to feed the second control section and the subsequent sections. This type of hydraulic circuit is referred to as a ‘series circuit’. One of the known problems of the series circuit occurs in the case of simultaneous operation of several hydraulic cylinders. For example, when the first section of the control valve (e.g., boom crane cylinder) and the second section of the control valve (e.g., bucket cylinder) are operated at the same time, the operations could deteriorate. In particular, if the cylinder controlled by the second control section reaches its limit switch, two undesirable functional faults can occur. The first is the pressurization of the series channel and thus of the cylinder chamber opposite the connection to the feed line, which leads to unintended movement of the cylinder itself in the opposite direction. Said problem is solved by the use of non-return valves along the series duct of the first control section to prevent back flow along the series channel itself with respect to the user-controlled direction. With the introduction of the non-return valve, once the limit switch of a work port controlled by a control section has been reached, there is a latching of the work ports operated by sections preceding the same one which has reached the limit switch, until the spool of the latter section is at least returned to the neutral position, reopening the previously mentioned free circulation LC channel. This can result in some difficulty for the operator and, in general, a feeling of poor maneuverability during the use of the operating machine. U.S. Pat. No. 11,255,353B2 describes a solution for overcoming the above-mentioned problems. In such document it is provided a bypass towards the outlet along the series line in such a way that if, during a simultaneous movement, the non-return valve of a cylinder reaching the limit switch closes the passage along the series line itself and effectively blocks the emptying of one of the cylinders upstream of the latter, the bypass allows the opening of said series channel towards the outlet and consequently the disposal of a flow rate. By disposing the flow rate, the movement of the cylinder upstream of the series duct itself is effectively enabled. The non-return valve seats are moved inside the control valve outside the spools, while on the spool a throttled connection is made between the channel of the series before the non-return valve towards the outlet inside the control spool of the section itself. However, such a solution requires providing the non-return valve seats on the control valve body at the channels of the series, effectively increasing the size of the control valve itself. Furthermore, the creation of a throttled passage on the spool between the series recess and that of the outlet leads to high-pressure drops and unwanted over-pressurization if the flow rate to be disposed of along the series channel upstream of the non-return valve is high. The need is therefore felt to improve the known solutions in multi-section hydraulic circuits with a series structure and free circulation. SUMMARY The technical problem at the basis of the present invention is to make available a valve device that is structur