The present invention refers to a control device for a hydraulic circuit. Moreover, the invention refers to a hydraulic system comprising said control device and an actuator which the control device acts on.
The present invention refers also to a method of controlling at least one hydraulic actuator.
Machines provided with hydraulic actuators and control systems configured to control such hydraulic actuators are known. One of the aspects to be considered when designing such machines is in relation to the safety, particularly to the safety of an operator; usually, the machine control system is responsible for managing abnormal conditions which could cause safety risks.
The safety of the machines is the subject, from a regulatory point of view, of standards aimed to establish some requirements necessary to reduce the safety risks, among which there is the EN ISO 13849. EN ISO 13849 is a harmonized type-B European standard which defines the parts of a control system of a machine which are required to implement the safety functions as parts of the control system regarding the safety and is devised to meet the safety base requirements defined by the European community directives. The standard is acknowledged, not only by the European community, but also by the regulatory systems of North America, Canada, Brazil, and Russia.
Substantially, the safety circuits according to the standard EN ISO 13849 are accepted as technical solutions for reducing the safety risks.
Some among the main safety risks can happen when there are anomalies or fails in the machine during its use; in this case, there could occur uncontrolled movements of the actuators which can cause a risk condition in proximity of the machine. For example, a falling actuator could cause an injury to an operator (risk of crushing, collisions, abrasions, etcetera).
The invention must be considered in the background herein described; the objects thereof being indicated in the following.
Additional prior art documents are the following.
Therefore, a main object of the present invention consists of providing a control device, a system and a method capable of overcoming the inconveniences beforehand described with reference to the prior art.
Consequently, an object of the present invention consists of minimizing or even eliminating the safety risks for an operator working in proximity of a machine or system operatively connected to the control device.
Particularly, an object of the present invention consists of determining and ensuring a safety function which involves the actuator at the occurrence of an anomaly and/or emergency conditions, by reducing or eliminating in this way the safety risk.
An additional object of the invention consists of providing a control device, a system and method according to the standard EN ISO 13849, and particularly to the standard EN ISO 13849-1 category 3 and according to a type "e" maximum reachable Performance Level (PL e); this means that in case of a single failing component, the safety function is anyway performed and ensured.
A further object of the invention consists of ensuring the safety function also in case of an electric supply outage or fail thereof.
An additional object of the present invention consists of disclosing a compact control device, in other words having a limited size, and being modular.
Moreover, the invention advances a technical solution being substantially effective and reliable (PL e).
These and other objects are met by a control device, a system and a method according to the following description, attached claims and following aspects.
The present invention is described by the control device of appended claim 1, the hydraulic system of appended claim 12 and the method of appended claim 15, of controlling at least one hydraulic actuator. Other preferred embodiments of the present description are set forth in the appended dependant claims.
The technical solution of the present invention, determining the substantially complete retraction of the rod into the box body in case of fail or malfunction or of an electric supply outage, enables to reduce the risks which the operator is subjected to, particularly with reference to the risk for the operator consisting in an uncontrolled movement of the hydraulic actuator which could crush the operator.
The redundancy levels enable to ensure a substantially complete retraction of the rod into the box body in case of fail or malfunction or of an electric supply outage and therefore contribute to reduce the risk which the operator is subjected to.
It is observed that in the following detailed description corresponding parts are indicated by the same numeral references. The figures could illustrate the object of the invention by not-to-scale representations; therefore, parts and components illustrated in the attached figures and regarding the object of the invention could only refer to schematic representations. In the context of the present invention the use of terms such as "on", "upper", "at the top", "under", "lower", "at the bottom", "sideways", "lateral", "laterally", "internal", "internally", "external", "externally", "horizontal", "horizontally", "vertical", "vertically", "front", "frontally", "rear", "rearward", "right", "left", similar terms and corresponding variants, save for specific different indications, refers to at least one spatial orientation which the object of the invention can take in condition of use. Save for different specific indications, the terms "condition" or "configuration" can be interchangeably used in the context of the present invention.
The configurations and connections which are described in the following refer, unless otherwise noted, to an anomaly and/or emergency condition which the control device and method according to the invention are configured to manage.
In the context of the present invention, one or more of the following definitions and conventions can be applied, when required and unless otherwise noted:
In order to have a better comprehension and to appreciate the advantages of the invention, some embodiments thereof will be illustratively described in a non a limiting way with reference to the attached drawings:
A control device according to the invention is generally indicated in the figures by the numeral reference 1. The control device 1 is configured to be connected to a hydraulic circuit associated to at least one actuator 7, 7L, 7R. In order to better comprehend the configurations and the functionalities of the control device 1, it is briefly described in the following the actuator 7, 7L, 7R; the numeral references of the actuator 7, 7L, 7R are mainly indicated in
The control device 1 comprises a supply/discharge section 2 which enables the connection to a pressurized fluid source P and to a discharge T, such as a discharge tank. The supply/discharge section is provided with a pressurized fluid supply port P' and a fluid discharge port T'. The pressurized fluid supply port P' is configured to be connected to the pressurized fluid source P' and, in a condition of connection to the pressurized fluid source P, to supply the control device 1 with pressurized fluid. The fluid discharge port T' is configured to discharge fluid from the control device 1 and, in condition of connection to the discharge T, to discharge fluid from the control device 1 to the discharge T. Preferably, the fluid is hydraulic oil.
Moreover, the control device 1 comprises at least one connection section 3 which enables the connection to the actuator 7, 7L, 7R. The connection section 3 comprises a first port B1', B1L', B1R' configured, at least in a condition of connection to the actuator (such as at least in an anomaly and/or in an emergency condition) to supply the actuator with pressurized fluid and a second port A1', A1 L', A1R' configured, at least in a condition of connection to the actuator (such at least one anomaly and/or emergency condition), to discharge fluid from the actuator. The first port B1', B1L', B1R' is connected to the port B1 leading to the first chamber 11 of the actuator and the second port A1', A1L', A1R' is connected to the port A1 leading to the second chamber 12 of the actuator; the first and second chambers 11, 12 of the actuator are opposite with respect to a piston 10 connected to the rod 9.
As illustrated in the figures from 1 to 6 with reference to the ports A1', B1', P', T' of the control device 1 according to three possible embodiments, the ports A1', A1L', A1R', B1', B1L', B1R', P', T' can be defined on the box body 4 of the control device 1. The box body 4 can comprise and contain at least partially circuit configurations of the control device 1. The control device 1 can comprise two connection sections 3, and consequently two first ports B1', B1L', B1R' and two second ports A1', A1L', A1R', and two supply/discharge sections 2, and therefore two pressurized fluid supply ports P' and two discharge ports T'; in further embodiments, the control device 1 could provide a number of connection sections 3 greater than two and, in addition or as an alternative, a number of supply/discharge sections 2 greater than two. As it is visible in Figures from 1 to 6 by illustrating the ports P', T', A1', B1', a connection section 3 and a supply/discharge section 2 can be defined on a face of a box body 4 of the control device 1, while the other connection section 3 and the other supply/discharge section 2 can be defined on a face of the box body 4 opposite to said face. Providing two or more connection sections and a corresponding number of ports enables to connect the control device 1 to the actuator at different portions of the box body 4 of the control device 1. Analogously, providing two or more supply/discharge sections 2 and a corresponding number of ports enables to connect the control device 1 to the pressurized fluid source P and to the discharge T at different portions of the box body 4 of the control device 1.
Moreover, the control device 1 comprises fluid lines developing between the supply/discharge section 2 and each connection section 3. The fluid lines can be at least partially or completely defined inside the box body 4. More particularly, the control device 1 comprises a pressurized fluid supply line and a fluid discharge line. The pressurized fluid supply lines develop between, and connects, the pressurized fluid supply port P' and the first port B1', B1L', B1R' and is configured, at least in a condition of connection to the actuator 7, 7L, 7R, to enable supply fluid to flow from the pressurized fluid supply port P' to the actuator 7, 7L, 7R. The fluid discharge line develops between, and connects the second port, A1', A1L', A1R' and the fluid discharge port T' and is configured, at least in a condition of connection to the actuator 7, 7L, 7R, to enable discharge fluid to flow from the actuator 7, 7L, 7R to the discharge port T'.
Moreover, the control device 1 comprises a control section configured both to control the actuator 7, 7L, 7R in one or more normal operative conditions ("steady" operative conditions) and to implement, in an extraordinary condition such as an anomaly and/or emergency conditions, a safety function operating on the actuator 7, 7L, 7R. More particularly, the safety function starts operating at the occurrence of a triggering condition, which indeed consists of the anomaly and/or emergency conditions and determines the complete retraction of the rod 9 of the actuator 7, 7L, 7R inside the box body 8.
The control section comprises an actuator drive member VA09, VA09L, VA09R configured to drive and/or manage one or more operative conditions of the actuator, and particularly in at least the normal operative conditions. As illustrated in the attached figures, the actuator drive member VA09, VA09L, VA09R is configured to operate according to a plurality of operative configurations. In the normal operative conditions, the fluid flows into the actuator drive member VA09, VA09L, VA09R, which drives the normal operation of the actuator 7, 7L, 7R. In the normal operative conditions, the actuator drive member VA09, VA09L, VA09R can therefore drive the retraction of the rod 9 into, or the exit of the rod 9 from the box body 8 because it is configured to operate at least between a condition in which it determines the retraction of the rod 9 into the box body 8 (retraction condition of the rod) and a condition in which it determines the exit of the rod 9 from the box body 8 (exit condition of the rod). In the retraction condition of the rod 9, the actuator drive member VA09, VA09L, VA09R enables both the passage of pressurized fluid from the pressurized fluid supply port P' to the first port B1', B1L', B1R' and the passage of fluid from the second port A1', A1L', A1R' to the fluid discharge port T', so that the pressurized fluid flows into the first chamber 11 and the fluid to be discharges flows out the second chamber 12 and flows from the second port A1', A1L', A1R' to the fluid discharge port T' in order to precisely determine the retraction of the rod 9 into the box body 8. In the condition of egress of the rod 9, the actuator drive member VA09, VA09L, VA09R enables both the passage of pressurized fluid from the pressurized fluid supply port P' to the second port A1', A1L', A1R' and the passage of fluid from the first port B1', B1L', B1R' to the fluid discharge port T', so that the pressurized fluid flows into the second chamber 12 and the fluid to be discharged flows from the first chamber 11 to the fluid discharge port T' in order to precisely determine the retraction of the rod 9 into the box body 8. The actuator drive member VA09, VA09L, VA09R is preferably a valve, particularly a servovalve.
Moreover, the control section comprises a first operative section 5 and second operative section 6, which enable to implement the safety function at the occurrence of the triggering condition. Both the first and second operative sections comprise a portion of the pressurized fluid supply line and a portion of the fluid discharge line.
The first operative section 5 is defined between the connection section 3 and the supply/discharge section 2. The first operative section 5 is fluidically connected to the supply/discharge section 2. More particularly, the first operative section 5 is defined at least between the supply/discharge section 2 and the actuator drive member VA09, VA09L, VA09R; such arrangement is defined with reference to the normal operative conditions in which the first operative section 5 and the actuator drive member VA09, VA09L, VA09R are in series to each other. With reference to the four embodiments which will be described in the following, the series arrangement of the first operative section 5 with the actuator drive member VA09 occurs in the normal operative condition, while the first operative section 5 is parallel to the actuator drive member VA09, VA09L, VA09R during the anomaly and/or emergency conditions. Substantially, at the occurrence of the triggering condition, the fluid flow in the circuit changes at least partially its path between the connection section 3 and the supply/discharge section 2 in order to switch the first operative section 5 from the series arrangement to the parallel arrangement with respect to the actuator drive member VA09, VA09L, VA09R. The first operative section 5 is configured, at the occurrence of the triggering condition, to enable fluid to flow from the fluid supply port P to the first port B1', B1L', B1R' and to enable fluid to flow from the second port A1', A1L', A1R' to the fluid discharge port T'. Optionally, the first operative section 5 can comprise the actuator drive member VA09, VA09L, VA09R (for example, in the second, third and fourth embodiments, in which the actuator drive member is functionally part of at least one between the first and second operative sections 5, 6 due to its safety position), which can therefore be functionally part of the first operative section 5.
The second operative section 6 is defined between the supply/discharge section 2 and the connection section 3. The second operative section 6 is defined at least between the actuator drive member VA09, VA09L, VA09R and the connection section 3; such arrangement is defined with reference to the normal operative condition in which the actuator drive member VA09, VA09L, VA09R and the second operative section 6 are in series to each other. With reference to the four embodiments which are described in the following, the series arrangement between the actuator drive member VA09, VA09L, VA09R and the second operative section 6 occurs in the normal operative condition, while the second operative section 6 is parallel to the actuator drive member VA09, VA09L, VA09R during the anomaly and/or emergency condition. Substantially, at the occurrence of the triggering condition, the fluid flow in the circuit changes at least partially its path between the connection section 3 and the supply/discharge section 2 in order to switch the second operative section 6 from the series arrangement to the parallel arrangement with respect to the actuator drive member VA09, VA09L, VA09R. The second operative section 6 is configured, at the occurrence of the triggering condition, at least to prevent fluid from flowing from the pressurized fluid supply port P', to the second port A1', A1L', A1R'. Optionally, the second operative section 6 can comprise the actuator drive member VA09, VA09L, VA09R (for example in the second, third and fourth embodiments, in which the actuator drive member is functionally part of at least one between the first and second operative sections 5, 6 due to its safety position) which thus can be functionally part of the second operative section 6.
According to the invention, the first and second operative sections 5, 6 are provided with at least one respective redundancy level and are configured, at the occurrence of the triggering condition, to ensure said retraction of the rod 9 by the respective redundancy levels. As it will be more particularly described in the following, each redundancy level provides at least two redundant elements which cooperate so that the function for which they are devised is performed also in case of a fail of one of said elements. The assurance of the retraction of the rod 9 is just given by the presence, at each provided redundancy level, of at least two redundant elements; consequently, if one of the redundant elements does not act the other redundant element or one of the other redundant elements of the same redundancy level acts.
The redundancy level of the first operative section 5 is defined on the pressurized fluid supply line and ensures, at the occurrence of the triggering condition, the flow of fluid from the fluid supply port P to the first port B1', B1L', B1R'. The redundancy level of the second operative section 6 is provided on the pressurized fluid supply line and ensures, at the occurrence of the triggering condition, to prevent fluid from flowing, from the pressurized fluid supply port P', to the second port A1', A1L', A1 R'. By making the pressurized fluid to flow to the first port B1', B1L', B1R' and not to the second port A1', A1 L', A1R', the control section enables and ensures the complete retraction of the rod 9 into the box body 8.
The control device 1 is interchangeable with the existent solutions which are not capable of performing a safety function according to the standard EN ISO 13849-1, in order to make them adapted to perform the safety function and consequently to make them compliant to said standard. Therefore, the control device 1 can be configured to enable to retrofit an existing machine or system 100 in order to ensure the compliance of the system or of the machine to the standard EN ISO 13849-1.
As it will be more specifically described in the following with reference to different embodiments of the control device 1, at least one between the first and second operative sections 5, 6 can comprise a further redundancy level. Preferably, both the first and second operative sections 5, 6 comprise respective further redundancy levels. Particularly, the further redundancy level of the first operative section 5 is defined on the discharge line and the further redundancy level of the second operative section 6 is also defined on the discharge line.
Moreover, the control section comprises a plurality of valves VA01-VA08, VA05L, VA05R, VA06L, VA06R, which contribute to one or more redundancy levels as hereinbelow described. The valves VA01-VA08, VA05L, VA05R, VA06L, VA06R can operate between an energized configuration (supplied condition) and a deenergized configuration; preferably, they are solenoid valves. The valves VA01-VA08, VA05L, VA05R, VA06L, VA06R preferably have an elastic element, such as a spring, which support the valve in the rest configuration in case of a current leak or cut of a supply wire. The valves VA01-VA08, VA05L, VA05R, VA06L, VA06R can be monitorable by a control unit, such as a programmable logic controller (PLC), of the hydraulic machine comprising at least one actuator which the control device 1 operates on. Among the types of valves VA01-VA08, VA05L, VA05R, VA06L, VA06R which can be used, it is mentioned in an exemplifying and non-limiting way the seat valves and the slide valves. The seat valves are substantially perfect tight valves; this type of valves does not have any fluid leakage and enables an optimal control of the hydraulic actuator.
Preferably, the control device 1 comprises two redundancy levels for each operative section. The following will more particularly describe a first, a second, a third, and a fourth embodiments of the invention, respectively illustrated in the
The pressurized fluid source P, the discharge T and the ports A1, A1L, A1R, B1, B1L, B1R of the actuator 7 are illustrated in the attached figures from 7 to 10 outside of the abovementioned broken line which encircle the corresponding circuit configuration of the control device 1; possible references P, T, A, B present inside of before mentioned broken line (in proximity of the actuator drive member VA09, VA09L, VA09R, for example) refer to the corresponding fluid line and illustrate a possible continuity or interruption of fluid (for example according to the arrows and symbols of the actuator drive member VA09, VA09L, VA09R which illustrate possible operative configuration) between the pressurized fluid source P or discharge T and/or a port A1, B1.
In the first embodiment of the control device 1, the configuration thereof is schematically illustrated in
Each redundancy level comprises a pair of valves VA01-VA08. With reference to the first operative section 5, the redundancy level located on the pressurized fluid supply line comprises the pair or redundant valves VA02, VA04, the further redundancy level located on the discharge line comprises the pair of redundant valves VA01, VA03. Referring now to the second operative section 6, the redundancy level thereof is defined on the pressurized fluid supply line and comprises the valves VA05, VA07 and its further redundancy level is defined in the fluid discharge line and comprises the valves VA06, VA08. For each pair of redundant valves, if there is a fail of or no supply to a valve, the function is ensured by the other redundant valve of the same pair of redundant valves.
The circuit configuration of the first embodiment, illustrating an anomaly and/or emergency conditions, can be summarized in this way: the control device 1 is supplied with pressurized hydraulic oil by the pressurized fluid source P through the port P'. The oil flow rate is adjusted by the one-way flow valve RG01. Independently from the position of the valve VA09 (
The first embodiment enables to implement the safety function by using eight solenoid valves VA01-VA08 (monitored by the control unit of the hydraulic machine comprising the actuator 7 which the control device 1 operates on) and a proportional solenoid valve VA09, particularly and as more specifically described in the following, a non-safety proportional solenoid valve VA09.
The valves VA01-VA08 can be monostable solenoid valves configured to operate between a rest position (deenergized condition) and an operative position (energized condition). The rest position, and consequently the operative position, are different among the valves VA01-VA04 and the valves VA05-VA08; the valves VA01-VA04 at rest enable the passage of fluid (on the contrary, they do not enable it in their operative position), while the valves VA05-VA08 at rest do not enable the passage of fluid in a direction, as indicated in the following (instead they enable it in their operative position). The solenoid valves VA01-VA08 are monitored by the control unit of the hydraulic machine so that, at the occurrence of an anomaly and/or emergency conditions, the control unit operates on them (therefore on the redundancy levels of the first and operative sections) for determining the implementation of the safety function.
In the first embodiment, the actuator drive member VA09 is a proportional solenoid valve and particularly a non-safety proportional solenoid valve, in other words a solenoid valve not apt to take a fail-safe position (safety position). It is understood the actuator drive member VA09 can be provided with any valve alternative to what was hereinbefore described or with an element apt to ensure the hereinbefore described functions.
As illustrated in
The state of the valves shown in the circuit configuration of
In the second embodiment of the control device 1, of which the circuit configuration is schematically illustrated in
The circuit configuration of the second embodiment, illustrating an anomaly and/or emergency conditions, can be summarized in this way: the control circuit 1 is supplied with pressurized hydraulic oil by the pressurized fluid source P through the port P'. The oil flow rate is adjusted by the one-direction flow valve RG01, the function and type thereof can be analogous to what was hereinbefore described with reference to the first embodiment. Independently from the position of the valve VA09 (
The second embodiment enables to implement the safety function by using six solenoid valves VA01-VA06 (monitored by the control unit of the hydraulic machine comprising the actuator 7 which the control device 1 operates on) and a proportional solenoid valve VA09 configured to take said safety position. The safety position corresponds to the case in which the ports P', T', A1', B1' are closed (see
The control device according to the second embodiment, can comprise one or more among the further components RG02, RP01, F01, RT01, RT02, RT03 of the beforehand type described with reference to the first embodiment.
In the third embodiment of the control device 1, of which the circuit configuration is schematically illustrated in
The circuit configuration of the third embodiment, illustrating an anomaly and/or emergency conditions, can be summarized in this way: the control device 1 is supplied with pressurized hydraulic oil from the pressurized fluid source P through the port P'. The pressurized oil flows into the first chamber 11 of the hydraulic actuator 7 through the port B1 determining the retraction of the rod 9. The retraction of the rod 9 is ensured because the oil flowing out of the port A1 can be discharged from the fluid discharge line through the valves VA02, VA06. The safety position of the actuator drive member VA09 also ensure the retraction of the rod 9. The valve VA05 and the actuator drive member VA09 in the safety position prevent pressure from entering into the second chamber 12 of the hydraulic actuator 7. In performing the safety function, the retraction of the rod 9 into the box body 8 is therefore ensured by:
The third embodiment enables to implement the safety function by using four solenoid valves VA01-VA04 (monitored by the control unit of the hydraulic machine comprising the actuator 7 which the control device 1 operates on) and a proportional solenoid valve VA09 configured to take said safety position. The safety position corresponds to the condition in which the port P' is fluidically communicating with the port B1' and the port T' is fluidically communicating with the port A1' (see
The control device according to the third embodiment can comprise one or more further components RG01, RG02, RP01, F01, RT01, RT02, RT03 of the beforehand type described with reference to the first embodiment.
The control device 1, according to the fourth embodiment, illustrated in
The fourth embodiment provides two actuator drive members VA09L and VA09R respectively configured to assist the left actuator 7L and the right actuator 7R. Each actuator drive member VA09L, VA09R is of the beforehand type described with reference to the third embodiment. In possible embodiments in which the control device 1 is configured to operate N actuators, it can comprise the same number N of actuator drive members so that each actuator drive member is configured to assist a respective actuator.
The first operative section 5 of the control device 1 assists both the actuators 7L, 7R and consequently is in common for the two actuators 7, while the control device 1 comprises a second section 6L dedicated to assist the left actuator 7L and a second section 6R dedicated to assist the right actuator 7R. In further embodiments which provide that the control device 1 is configured to operate on N actuators, the same number N of second sections can be provided, wherein each second section is apt to assist a respective actuator. In such embodiments, the first operative section 5 or a plurality of first operative sections 5 are provided to assist all the N actuators, each of them can assist one or more actuators as a function of the selected circuit configuration.
The circuit configuration of the fourth embodiment, illustrating an anomaly and/or emergency conditions, can be summarized in this way: the control device 1 is supplied with pressurized hydraulic oil from the pressurized fluid source P through the port P'. The pressurized oil flows into the respective first chambers 11 of the hydraulic actuators 7L, 7R through the respective ports B1L, B1R determining the retraction of the rod 9 of each actuator 7L, 7R. The retraction of the rod 9 is ensured because the oil flowing out of the ports A1L, A1R can be discharged from the fluid discharge line through the valves VA02, VA04, VA05, VA05R and the safety position of the actuator drive members VA09L, VA09R. The valves VA05L, VA05R and the actuator drive members VA09L, VA09R in the safety position prevent pressure from entering the second chamber 12 of the respective hydraulic actuator 7L, 7R which they assist. In performing the safety function, the retraction of the rod 9 into the box body 8 of the actuators 7L, 7R is consequently ensured by:
More particularly, in performing the safety function, the retraction of the rod 9 into the box body 8 of the left actuator 7L is ensured by:
The fourth embodiment enables to implement the safety function on two hydraulic actuators 7L,7R by eight solenoid valves VA01-VA04, VA05L, VA05R, VA06L, VA06R (monitored by the control unit of the hydraulic machine comprising the actuator 7 which the control device 1 operates on) and two proportional solenoid valves VA09L, VA09R configured to take said safety position. The safety position of the proportional solenoid valves VA09L, VA09R corresponds to the case in which the port P' is fluidically communicating with the ports B1 L', B1R' and the port T' is fluidically communicating with the ports A1L', A1R' (see
The control device 1, according to the fourth embodiment, can comprise one or more among the further components RG01, RG02, RP01 (particularly RP01L which assist the left actuator and RP01R which assists the right actuator), F01, RT01 (particularly RT01 L which assists the left actuator and RT01R which assists the right actuator), RT02 (particularly RT02L which assists the left actuator and RT02R which assists the right actuator) of the beforehand type described with reference to the first embodiment.
Four embodiments of the control device 1 have been described in an illustrative way; it is understood that possible further embodiments and/or combinations of the described embodiments are possible.
Now it must be specified as, due to the specific arrangement and functionality of the first section 5, second section 6 and due to the safety function the control device 1 is configured to implement, the control device 1 is configured to make the hydraulic circuit or a hydraulic system 100 which is associated to, compliant to the requirements of the standard EN ISO 13849, preferably according to the standard EN ISO 13849-1, still more preferably according to the standard EN ISO 13849-1 category 3.
The technical features herein disclosed with reference to functions of the control device 1 can be applied in the field of corresponding uses of the device or steps of the method which will be described in the following and can consequently be used for specifying such uses and method in the attached claims.
Moreover, the invention refers to a use of the beforehand described control device 1 for controlling and implementing a safety function on at least one actuator 7, 7L, 7R, for example on at least one hydraulic actuator 7, 7L, 7R of a hydraulic machine such as a calender or a press. The safety function is of the beforehand described type and provides to retract the rod of the actuator inside the box body. Using the control device 1 ensures, at the occurrence of an anomaly and/or emergency condition, to perform the safety function by the redundancy levels of the control device 1.
Further, the invention refers to a system 100 comprising a control device 1 of the beforehand described type.
Preferably, the system 100 is of a hydraulic type and comprises a hydraulic circuit associated to a pressurized fluid source P and to a fluid discharge T. The pressurized fluid source P is configured to supply pressurized fluid also without an electric supply; this enables to implement the safety function by the control device 1 also without an electric supply. For example, the pressurized fluid source P can be a pressurized fluid storage and/or supply group, such as an oil storage and/or supply group.
The system 100 comprises at least one actuator 7, 7L, 7R associated to the hydraulic circuit. The actuator 7, 7L, 7R can be of the type beforehand described. Specifically, the actuator 7, 7L, 7R comprises a box body 8 such as a cylinder and a rod 9 movable with respect to the box body and is configured to move a movable mass M. The control device 1 is connected to the actuator 7, 7L, 7R at the connection section 3 and to the hydraulic circuit at the supply/discharge section 2. More particularly, the system 100 can comprise the hydraulic machine provided with at least one actuator 7 or a pair of actuators 7L, 7R and/or possible additional actuators which the control device 1 is configured to assist.
The system 100 has a control unit, which is preferably part of the hydraulic machine and can be a programmable logic controller (PLC). The control unit is configured to monitor the valves VA01-VA08 and to drive the rest or operative positions. More specifically, the control unit is configured to control the correct operation of each valve VA01-VA08 and the correct implementation of operative logics.
The control unit is configured to detect a triggering condition and, following the detection of the triggering condition, to implement the beforehand described safety function by the control device 1. The triggering condition is of the beforehand described type. Possible triggering conditions are: no electric supply or fail or anomaly in one of the electric components of the hydraulic circuit (for example electric anomaly of one or more valves VA01-VA08, cut cables, etcetera), combination of "non-safe" positions of the valves (for example, failing in taking the correct rest position of a valve VA01-VA08) or discrepancy between the driven position and effective position of one or more valves VA01-VA08, presence of a person in a risk area defined in proximity of the actuator 7, 7L, 7R and/or of the machine, etcetera.
At the end of the safety function, the cause of the triggering condition, such as an anomaly or malfunction, can be detected or signaled by the control unit of the machine.
The technical features herein disclosed with reference to functions of the system 100 can be applied in the field of corresponding uses of the system 100, or of the control device 1 or steps of the control method of at least one hydraulic actuator which is described in the following.
The present invention refers also to a method of controlling at least one hydraulic actuator 7, 7L, 7R. Preferably, the method is performed by the beforehand described control device 1, on at least one actuator 7 or a pair of actuators 7L, 7R and/or possible additional actuators also of the beforehand described type.
The method provides to connect the control device 1 to at least one actuator 7, 7L, 7R by the connection section or, if it is already connected, to verify its correct connection. Further, the method provides to detect a triggering condition which can be one among the beforehand described ones or a further anomaly and/or emergency conditions.
Following the detection of the triggering condition, the method provides to implement a safety function by the control device; the safety function is according to what was hereinbefore described. The implementation of the safety function by the control device 1 provides to supply the first chamber B1, B1L, B1R of the actuator 7, 7L, 7R with pressurized fluid and discharge pressurized fluid from the second chamber A1, A1L, A1R of the actuator 7, 7L, 7R, in order to determine the retraction of the rod 9 inside the box body 8. Supplying the first chamber B1, B1L, B1R preferably provides to flow the pressurized fluid in the pressurized fluid supply line through the first operative section 5 and, downstream the first operative section 5, through the first port B1', B1L', B1R'. Discharging the pressurized fluid from the second chamber A1, A1L, A1R of the actuator 7, 7L, 7R preferably provides to flow fluid in the discharge line at least through the first operative section 5 and, upstream the first operative section 5, through the second port A1', A1L', A1R'.
Retracting the rod 9 inside the box body 8 enables it to take a safety position inside the box body; such safety position is a position determining the implementation of safety measures for the movable mass M, pulled in a controlled way (consequently substantially without risks) by the rod 9 during its retraction stroke. The retraction of the rod is ensured by the redundancy levels of the first and second operative sections beforehand described with reference to the control device 1 and to possible embodiments thereof, which correspond to possible embodiments of the method.
In the first and second embodiments of the method, the step of implementing a safety function by the control device can provide to prevent fluid from flowing through the actuator drive member.
With reference to the third and fourth embodiments of the method, the step of implementing a safety function by the control device can provide to enable the passage of fluid flow, particularly the passage of "crossed" fluid as hereinbefore described through the actuator drive member when the actuator drive member is in the fail-safe condition.
The method can provide, at the end of the performance of the safety function, to detect and signal the cause of the triggering condition, such as an anomaly or malfunction.
The technical features herein disclosed with reference to the steps of the method, can be applied in the field of corresponding beforehand described functions or uses of the control device 1 and therefore can be used for specifying such functions or uses of the device in the attached claims.
The following describes some of the many advantages the invention provides. First of all, the invention provides a control device 1, which is modular and compact, in other words having limited dimensions. The modularity of the control device 1 is due to the fact that it comprises a plurality of subgroups (modules) which can be reconfigured and assembled in different ways in order to obtain a more efficient size for the integration with the machine; each mode of assembly determines an embodiment such as the ones beforehand illustrated. The subgroups which can be assembled in different ways can consist of the valves VA01-VA08, VA05L, VA05R, VA06L, VA06R and respective connectors (see the blocks connected to said valves and illustrated in Figures from 1 to 6) and of the actuator drive member VA09, VA09L, VA09R and relevant respective (see the blocks connected to the actuator drive member VA09 and illustrated in the Figures from 1 to 6).
The invention enables to use different types of servovalves VA09, VA09L, VA09R to drive the hydraulic actuator during the normal operation of the machine without jeopardizing the safety function; the type of servovalve VA09, VA09L, VA09R can therefore be selected only as a function of the type of control to be performed. Moreover, the invention further enables to use oil having a high filtration grade (less filtered oil), densities comprised between 10 and 800 cst (kinematic viscosity) and temperatures comprised between -20°C and +70°C without jeopardizing the safety function. Moreover, the invention enables to reduce the operative cost of the machine and to operate with pressures to 350 bar.
The configurations of the described hydraulic circuits show a reduced probability of having simultaneous fails (common cause fail, CCF) because the control device 1 is not sensible to the environmental conditions, because the quality of the hydraulic oil for implementing the safety function is irrelevant and because the electric connections of the electrovalves VA01-VA08, VA05L, VA05R, VA06L, VA06R are insensible to the electromagnetic noises.
Lastly, the invention provides a technical solution of remarkable efficiency and reliability. Indeed, the control device 1 has the following probabilities of failing:
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