Patent Publication Number: US-2011071691-A1

Title: Industrial device controlled through a power over ethernet system

Description:
FIELD OF THE INVENTION 
     The present invention relates to an industrial device and industrial device actuator for use in an industrial process or system and, in particular, for an industrial device and industrial device actuator controlled through a power over Ethernet system. 
     BACKGROUND OF THE INVENTION 
     Ethernet systems have long been well known to those of ordinary skill in the data communications arts as one of the most common and widely used system for communication all forms of data between digital devices, such computers. In the original Ethernet systems all of the computers in a system were connected to a single transmission line, such as a coaxial cable, and each computer in turn transmitted data packets to receiving computers. Access to the transmission line by the computers was controlled by any of a wide variety of access protocols and all packets were transmitted to all of the computers on the line, with each computer capturing those packets addressed to it by means of an address residing in each of the packets. 
     Ethernet systems have since expanding in power, complexity and speed and an Ethernet system may now be comprised of multiple networks arranged in a variety of configurations and interconnected through devices and sub-systems such as repeaters, bridges, routers, hubs and switches so that data packets may be routed to only a designated receiver or small group of receivers. In a like manner, the transmission lines now include, for example, twisted and shielded pairs, multiple conductor cables, fiber optic cables, radio and satellite links, and so forth, the devices have expanded to include such relatively small and low power devices as cameras, cell phones, printers, storage devices, and so forth. 
     Despite radical changes and advances in Ethernet net hardware and devices, however, Ethernet has retained the same standardized, uniform data formats and protocols so that any Ethernet system can communicate with any new, present or previously existing system. 
     A more recent development of Ethernet systems is “power over Ethernet”, also referred to by the abbreviation “PoE”, which is the transmission of limited amounts of power over standard multi-conductor Ethernet cables with DC power being carried either on conductors designated for DC power transmission, with other conductors being designated for data, or with the DC power being carried on the same conductors as data, with the data being separated from the DC power at the receiving end by transformers or other DC/AC separation circuits. 
     PoE networks offer significant advantages over systems employing separate data communication and power transmission systems, such as less cost because a PoE system requires only a single, lighter transmission line for both power and data while a conventional system requires a data line and a heavy power line and because the installation of PoE cabling does not require qualified or licensed technicians electricians. In addition, PoE networks may be used where, for example, time, space or cost constraints prohibit or limit the use or value of conventional AC power systems, such as temporary installations or installations in existing structures. 
     At present, however, and although PoE networks can carry more power than Universal Serial Bus (USB) systems, which is a short range data bus communication standard used primarily by computers and peripheral devices, PoE systems have been used only for lower power, computer related devices such as telephones, wireless LAN (local area network) systems, camera systems, small Ethernet switches, “thin” clients, LCD (liquid crystal display) and laser diode devices and MIDI (musical instrument digital interface) devices. 
     There are a number of applications, however, where the benefits of PoE networks would provide all of the advantages discussed above, but where PoE networks are not used because the power requirements of the devices to be controlled or monitored typically exceed the power available through PoE networks. Such applications typically include various forms of industrial systems involving, for example, the remote control of valves, pumps and other devices used to control and regulate various industrial processes and, because of their power requirements, may controlled through a network such as Ethernet but are powered by separate AC power lines. 
     The present invention provides a solution to these and related problems of the prior art. 
     SUMMARY OF THE INVENTION 
     Wherefore, it is an object of the present invention to overcome the above mentioned shortcomings and drawbacks associated with the prior art. 
     The present invention is directed to an industrial device controlled and powered through a power over Ethernet system and an Ethernet system for controlling and powering an industrial process mechanism wherein the industrial device includes an industrial process mechanism and a device controller. The device controller includes a control processor connected from a data output and a power output of a power over Ethernet receiving circuit for receiving data including control instructions from the Ethernet and generating corresponding actuator control commands and an actuator connected from the power output over Ethernet receiving circuit and responsive to the actuator control commands for controlling operation of the industrial process a power level less than or equal to a power level defined by an industry standard for a power over internet system and a force multiplication mechanism driving the industrial process mechanism. 
     A system for controlling and powering an industrial process mechanism through an Ethernet system includes an Ethernet system communicating at least data including control instructions between a system controller and a device controller for controlling the industrial process mechanism, one of an endspan and a midspan for communicating data between the device controller and providing power to the device controller through an Ethernet transmission line, and the device controller. The device controller includes a power over Ethernet receiving circuit for receiving data and power from the one of the endspan and the midspan and for transmitting data to the one of the endspan and the midspan, a control processor connected from a data output and a power output of a power over the Ethernet receiving circuit for receiving data including control instructions from the Ethernet and generating corresponding actuator control commands, and an actuator connected from the power output over Ethernet receiving circuit and responsive to the actuator control commands for controlling operation of the industrial process mechanism wherein the actuator includes a low power drive mechanism requiring less than a power level defined and limited by the Ethernet connection, such as the 12 watts defined in the industry standard for a currently common version of the Ethernet or 25 watts defined in a pending new version of the industry standard, and a force multiplication mechanism driving the industrial process mechanism. 
     The low power drive mechanism may be a rotational driver or a linear driver comprised of either an electric motor or a hydraulic device, the force multiplication mechanism may be a gear train, a rack and pinion mechanism, a lever mechanism or a hydraulic mechanism, and the industrial process mechanism may be a valve, a pump, a motor or an actuator for a subsequent industrial process mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The invention will now be described, by way of example, with reference to the accompanying drawings in which: 
         FIG. 1  is a diagrammatic illustration of an exemplary industrial power over Ethernet system for controlling and powering a controlled device for controlling an industrial process mechanism; 
         FIGS. 2A and 2B  are schematic illustrations of power over Ethernet transmission circuits; 
         FIG. 2C  is a schematic representation of a power over Ethernet receiving circuit; 
         FIG. 3  is a diagrammatic illustration of a controlled device; and, 
         FIG. 4  is an isometric representation of a controlled device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Referring to  FIG. 1 , therein is shown a diagrammatic representation of an exemplary industrial PoE system  10  according to the present invention. As illustrated therein, an industrial PoE system  10  includes one or more controlled devices  12  such as, for example, valves, pumps, actuators and other devices for controlling and regulating various industrial processes, and an Ethernet network  14  for communicating data, such as control commands and monitoring information, between one or more system controllers  16  and controlled devices  12 . It is to be understood that network  14  may be comprised of any configuration or arrangement of a network or networks, including local and wide area networks or sub-systems of any configuration using any form of transmission line or connection, including, for example, coaxial cables, twisted and shielded pairs, multiple conductor cables, fiber optic cables, radio and satellite links, and including any number and configuration or arrangement of sub-systems, repeaters, bridges, routers, hubs and switches. 
     In a PoE system, such as the PoE system  10  illustrated in  FIG. 1 , the last segments or “spans”  18  of network  14  connecting the controlled devices  12  to the remainder of Ethernet network  14  and thus eventually to system controllers  16  are comprised of PoE spans  18 , that is, are comprised of Ethernet transmission lines carrying both data and power. As shown in  FIG. 1 , the end of each PoE span  18  interfacing with Ethernet network  14  is comprised of either an “endspan”  18 E or a “midspan”  18 M which is interposed into the PoE span  18  between an Ethernet switch  18 S, which in turn interfaces to Ethernet network  14 , and the controlled device or devices  12 . 
     Endspans  18 E and midspans  18 M both perform the function of combining the data from Ethernet network  14  with DC power from a power source  18 P to deliver the DC power and data to the controlled device or devices  12  through the PoE span  18 . Endspans  18 E, however, are Ethernet PoE switches including PoE circuitry for combining DC power with the data to be transmitted to the controlled device or devices  12  is performed within the switch. Midspans  18 M, in turn, are “power injectors” inserted between conventional Ethernet switches, that is, Ethernet switches not having the capability to combining the DC power with the data stream for transmission to the controlled device or devices  12 , and contain PoE circuitry for combining DC power with the data to be transmitted to the controlled device or devices  12 . Endspans  18 E are typically used, for example, in new installations, while midspans  18 M are typically used in existing installations to add PoE capability without the need to replace and configure a new Ethernet switch. Endspans  18 E, however, may be added to existing installations in replacement of existing switches while midspans  18 M may be used in new installations for various reasons, such as providing a temporary PoE capability or where endspans  18 E are not available or are not practical. 
     Lastly with respect to endspans  18 E and midspans  18 M, it should be noted that there are presently two standard methods for delivering DC power and data from an endspan  18 E or midspan  18 M to a controlled device or devices  12 . In the first method, illustrated in  FIG. 2A , a PoE transmission circuit  18 T in the endspan  18 R or midspan  18 M combines the DC power onto the same transmission lines or conductors for transmission tot he controlled device or devices  12 . In the alternative method, illustrated in  FIG. 2B , the PoE transmission circuit  18 T in the endspan  18 E or midspan  18 M transmits the data to the controlled device or devices  12  on one set of transmission lines or conductors and the DC power to the controlled device of devices  12  on another set of transmission lines or conductors. A controlled device  12  will correspondingly include a PoE receiving circuit  18 C as illustrated in  FIG. 2C  for receiving and separating the DC power and data signals, with a PoE receiving circuit  18 C being typically designed to operate with both methods for delivering the DC power and data. 
     It must also be noted that a PoE receiving circuit  18 C also transmits data from the controlled device  12  to the PoE transmission circuit  18 T and that a PoE transmitting circuit  18 T, in addition to transmitting power and data to a PoE receiving circuit  18 C receives data from a PoE receiving circuit  18 C and transmits the data onto the Ethernet network  14 . 
     Referring to  FIG. 3 , therein is a diagrammatic illustration of a controlled device  12  of the present invention that is controlled and powered through a PoE span  18  of an Ethernet network  14 . As shown therein, a controlled device  12  includes an industrial process mechanism  20 M for controlling, monitoring or regulating an industrial processes, such as a valve, pump, motor or linear or rotational actuator and a device controller  20 C that includes a PoE circuit  18 C for receiving and separating DC power and data received from and endspan  18 E or midspan  18 M. 
     Device controller  20 C will also include a control processor  12 P connected from data output  20 D and power output  20 P of PoE circuit  18 C and will interpret commands received through data output  20 D from the data transmitted to the controlled device  12  to in turn provide actuator control command outputs  20 CA to an actuator  20 A, which also receives DC power from power output  20 P of PoE circuit  18 C. Actuator  20 A will in turn control and actuate the industrial process mechanism  20 M and will monitor the state of industrial process mechanism  20 M to provide corresponding mechanism state outputs  20 MS to control processor  12 C, which will in turn transmit data representing mechanism state outputs  20 MS through the PoE span  18  and network  14  to the system controller or controllers  16 . 
     According to the present invention, actuator  20 A is a rotational or linear actuation device including a low power drive mechanism  22 D requiring less than the 12 watts defined in a currently adopted PoE standard or the 25 watts defined in a pending PoE standard or as otherwise defined by PoE standards. The drive mechanism may include such elements as a rotational or linear electric motor or hydraulic motor or piston, and mechanical force multiplication mechanism  22 M, such as an a gear train, rack and pinion mechanism, lever mechanism or hydraulic piston mechanism, providing a force multiplication sufficient to allow a drive mechanism  22 D to drive the actuation of an industrial process mechanism  20 M. The force multiplication mechanism  22 M may thereby trade speed of actuation for actuating force or, in alternate embodiments, the industrial process mechanism  20 M may be of a design requiring relatively little actuating force, such as a Teflon seal and bearing ball valve, or may be a low power actuator for a subsequent industrial process mechanism, such as a hydraulic control valve controlling a hydraulic pressure that in turn controls a significantly larger mechanism. 
     An exploded view of an exemplary controlled device  12  of the present invention is illustrated in  FIG. 4  wherein, as shown, the industrial process mechanism  20 M is comprised of a rotary ball valve  20 V and the device controller  20 C is constructed as a single assembly with the ball valve, being contained in a controller housing  20 H mounted onto the ball valve mechanism. In this exemplary embodiment the low power drive mechanism  22 D is comprised of an electric motor, the force multiplication mechanism  20 M is comprised of a gear train and the control processor  12 P and PoE circuit  18 C reside on circuit boards within the controller housing  20 H. 
     It should also be noted that a user interface at a system controller  16  for the input of control commands for an industrial process mechanism  20 M and the display of state outputs  20 MS representing the operating state of the industrial process mechanism  20 M may be implemented in a number of ways. For example, a system controller  16  will typically include a display  16 D and a control input mechanism  16 C, such as a keyboard, mouse or touch screen display implemented on display  16 D. In one implementation, and for example, the system controller  16  may store a graphical interface representation of control inputs, such as open/close or on/off buttons and control displays, such as representations of the operating state of a industrial process mechanism  20 M to generate control inputs to the transmitted as data to the controlled device  12  and to display the state outputs  20 MS transmitted as data from the controlled device  12 . In another example, the controller processor  12 C or an associated memory in the controlled device  12  may store the general equivalent of the above discussed graphical interface representation of control inputs and outputs in, for example, the form of a hypertext markup language page  12 P, that is, a web page, or equivalent, to be transmitted to and displayed at a system controller  16  as discussed above, thereby allowing any system controller  16  having network  14  access to the controlled device  12  to control the controlled device  12 . 
     Since certain changes may be made in the above described system and method for control of industrial process mechanisms through PoE Ethernet systems without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.