|Publication number||US20040011194 A1|
|Application number||US 10/398,619|
|Publication date||Jan 22, 2004|
|Filing date||Oct 2, 2001|
|Priority date||Oct 10, 2000|
|Also published as||DE10049958A1, DE10049958B4, EP1325237A1, EP1325237B1, WO2002031364A1|
|Publication number||10398619, 398619, PCT/2001/11378, PCT/EP/1/011378, PCT/EP/1/11378, PCT/EP/2001/011378, PCT/EP/2001/11378, PCT/EP1/011378, PCT/EP1/11378, PCT/EP1011378, PCT/EP111378, PCT/EP2001/011378, PCT/EP2001/11378, PCT/EP2001011378, PCT/EP200111378, US 2004/0011194 A1, US 2004/011194 A1, US 20040011194 A1, US 20040011194A1, US 2004011194 A1, US 2004011194A1, US-A1-20040011194, US-A1-2004011194, US2004/0011194A1, US2004/011194A1, US20040011194 A1, US20040011194A1, US2004011194 A1, US2004011194A1|
|Inventors||Thomas Lederer, Achim Ziegele, Alexander Aichele|
|Original Assignee||Thomas Lederer, Achim Ziegele, Alexander Aichele|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (10), Classifications (9), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
 The present invention relates to a fluid power arrangement comprising at least one fluid power actuator, which may be operated by means of a valve arrangement via at least a first and second fluid line using fluid power, at least one electrical component being provided on the actuator for connection with a control module. Furthermore, the invention relates to an actuator and a valve arrangement each for a fluid power arrangement of this type.
 Such a fluid power arrangement is for instance disclosed in the German patent publication 198,827,833 A1. In this case so-called double-acting cylinder are illustrated as actuators, whose pistons are able to be moved in two opposite directions and are each able to be driven into a terminal position. The cylinders are operated by compressed air supplied through a pair of compressed air lines joined with the piston rod gland end and at the opposite end from a valve arrangement. For operation of the cylinders valves arranged in the valve arrangement cause the supply of pressure medium or venting of the cylinder chambers. Using sensors the respective piston position in the cylinders is detected and by way of separate electrical connection lines such position is communicated to a control device.
 In the case of this conventional fluid power arrangement in each case two compressed air lines and also two electrical connection lines must be connected with each cylinder. The amount of wiring and hose configuration work is therefore substantial.
 There has already been a suggestion to solve this problem in the said German patent publication 198,827,833 A1 by arranging the valves for each cylinder directly on the cylinders and having only one compressed air supply line extending to the cylinder. Furthermore there is a suggestion to provide the compressed air supply line with a plurality of electrical lines, which partly serve for electrical power supply to the electrical components of the cylinder and partly for the transmission of data between the control device and also the valves and sensors.
 There is admittedly on the one hand a reduction in the amount of fluid line required with this design. However, on the other hand expensive and complexly arranged flexible compressed air lines having several electrical conductors are necessary, which in addition make necessary complex connections for joining the compressed air lines with the cylinders and also the compressed air supply system.
 Accordingly one object of the invention is to provide a straightforward and readily handled, economic fluid power arrangement. Furthermore, a valve arrangement and an actuator are proposed, which are more especially suitable for such a fluid power arrangement.
 This object is to be achieved using a fluid power arrangement of the type initially mentioned, in the case of which the valve arrangement and the actuator are connected together by way of a first and a second electrical connection, by way of which the valve arrangement supplies the actuator with electrical energy by the provision of a voltage, the first electrical connection being by way of the first fluid line and the second electrical connection being by way of the second fluid line or by way of a joint ground potential between the actuator and the valve arrangement and the actuator and the valve arrangement are respectively provided with signal producing and or signal detecting means for establishing a signal connection between the at least one electrical component and the control module by way of the first and the second electrical connection.
 In order to attain the object of the valve there is furthermore the provision of an actuator in accordance with technical teaching of claim 18 and a valve arrangement in accordance with technical teaching of claim 19,
 The principle of the invention is to form a current circuit between the actuator and the valve arrangement, by way of which circuit the actuator is on the one hand supplied with electrical energy and on the other hand an electrical signal connection is produced between the electrical component or components of the actuator and the control module. In this case a first fluid line leading to the actuator, as for example a compressed air or hydraulic line, is utilized not only for the supply and removal of fluid, but also as an electrical connection line between the valve arrangement and the actuator. The fluid line is for this purpose electrically conductive or is provided with an electrical conductor.
 The current circuit between the actuator and the valve arrangement is, in a preferred embodiment, connected by way of a second electrically conductive fluid line.
 In accordance with a further embodiment the second electrically conductive fluid line is not necessary. Instead of it the combined energy and signal current circuit between the actuator and the valve arrangement is completed by way of a common ground potential between the actuator and the valve arrangement.
 In any case the energy supply and signal transmission are by way of a single, common current circuit, for which no electrical lines separate from the fluid lines are necessary. In this case the complexity of manufacture is reduced as well, since the fluid lines do not have to be fitted with a plurality of electrical conductors, and in fact only have one single electrical conductor. The actuator may furthermore be made compact, since valves employed for its operation may be arranged remote from it on the valve arrangement. Furthermore, the control module may, if it has a suitable diagnostic means, diagnose the interruption of one of the fluid lines on the basis of the interruption of the respective electrical connection with the respective fluid line.
 Further advantageous developments of the invention are recited in the dependent claims and in the specification.
 For signal transmission in the monitoring direction from the actuator to the control module the signal producing and/or signal detecting means of the actuator preferably comprise, as communication means, a modulator for modulating the voltage with monitoring signals and on the other hand the signal producing and/or signal detecting means, (which are associated with the valve arrangement) comprise as a communication means a demodulator for demodulating the voltage to get the monitoring the signals from the voltage. The modulator and the demodulator transmit serially digitally encoded pulse sequences.
 For the control of the actuator by the control module in the control direction the signal producing means, associated with the valve arrangement, comprise as communication means a modulator for the supply of control signals by modulation of the voltage. The signal detection means of the actuator then use a demodulator to recover the control signals from the voltage. Furthermore, the modulator-demodulator combination also transmits serially digitally encoded pulse sequences.
 The signal producing and/or signal detecting means associated with the valve arrangement preferably form a component of the valve arrangement. They may however in principle be a component of, for example, the control module or a bus node of a field bus, which is provided between the valve arrangement and the control module.
 It is an advantage for the signal producing and/or signal detecting means associated with the valve arrangement to include a bus interface provided for communication between the valve arrangement and the control module.
 The assembly of the fluid power arrangement is facilitated as regards the actuator and/or the valve arrangement by having connection means more particularly in the form of plug connection means, in the case of which in a single manipulation both a fluid power and also an electrical connection is advantageously produced. For this purpose it is for example suitable to employ an electrically conductive screw or plug connection for the fluid line.
 Preferably, the first and/or the second fluid lines only have just one single electrical conductor, which may be designed in different ways. A fluid line in the form of a flexible hose may for instance be provided with only one electrically conductive wire braid structure or with an electrically conductive foil. A rigid fluid line, as for example a metal tube, may as such serve as an electrical conductor and is, if necessary, externally provided with electrical insulation.
 In accordance with a preferred modification of the invention the signal producing means impress, for signal production, a current flow on the signal connection. For this purpose transistor circuits are suitable as signal production means or more preferably furthermore diodes, which respectively only permit a predetermined current flow. The signal detection means then ascertain the respective current flow, for example with a shunt resistor and may in this manner comprise signals from the at least one electrical component. It is then extremely simple to attain a current flow for signal production also using one or more resistors having different resistance values.
 In the following the invention and its advantages will be described with reference to working examples as illustrated in the accompanying drawings.
FIG. 1 shows a first working embodiment of a fluid power arrangement in accordance with the invention with an actuator which is connected by way of two fluid lines each with a respective additional electrical conductor with a valve arrangement.
FIG. 2 represents a further development of the working example of FIG. 1 with a further actuator and a further valve arrangement.
FIG. 3 shows a modification of the working embodiment of FIG. 1 in the case of which an electrical connection is provided between the valve arrangement and the actuator using a common ground potential.
FIG. 4 is a diagrammatic view of a modification of the working example of FIG. 1 in the case of which the signal producing means of the actuator set impressed current flows on the signal connection with the valve arrangement.
FIG. 1 diagrammatically shows a fluid power arrangement, which is in the present case electro-pneumatic, having an actuator 10, which as a drive element has a cylinder 11. The actuator 10 may also comprise a different type of fluid operated drive, as for example a rotary drive or piston rod-less linear drive. The cylinder 11 is able to be operated using a valve arrangement 12 controlling the flow of compressed air, a piston 27 in the cylinder 11 being reciprocated in a cylinder chamber 9. For the actuation of the cylinder 11 using compressed air compressed air lines 13 and 14 are arranged between the valve arrangement 12 and the actuator 10, such lines being for example in the form of flexible hose lines or rigid metal tubes. The compressed air lines 13 and 14 are connected by way of connection means 15 and 16, which constitute connection means, with the valve arrangement 12 and by way of connections 17 and 18 are connected with the actuator 10. In the present case the connections 17 and 18 arranged in pairs on a common side of the actuator 10, although they may be in principle arranged on opposite sides, for example. The connections 15 through 18 may for example be plug connections or screw connections.
 In the valve arrangement 12 compressed air ducts 20 and 21 lead from the connections 15 and, respectively, 16 to a valve 19, which controls pressurization or venting of the compressed air lines 13 and 14. A compressed air supply means, not illustrated, for example in the form of compressed air producing device and a servicing device, supplies the valve 19 with compressed air. The valve 19 is connected by way of a compressed air supply distribution system, only represented by one compressed air supply line 22 with the compressed air supply means. The valve 19 constitutes an integral component of the valve arrangement 12 or it is a replaceable separate valve able to be arranged on the valve arrangement 12, for example by plugging in place. In addition to the valve 19 the valve arrangement 12 may comprise further valve, not illustrated.
 In the actuator 10 a compressed air duct 23 leads from the connection 17 to a cylinder space 24, in the end plate head of the cylinder, of the cylinder chamber 9 and a compressed air duct 25 runs to the piston rod gland end cylinder space of cylinder chamber. When the valve 19 pressurizes the compressed air line 13 with compressed air and at the same time vents the compressed air line 14, the piston 27 of the cylinder 11 will be moved toward cylinder space 26 in the cylinder head. The piston 27 will move toward the space 24 when the valve 19 pressurizes the cylinder space 26 in the cylinder head by way of the compressed air line 14 and vents the compressed air line 13.
 The valve arrangement 12 and the actuator 10 are connected with one another by way of connecting lines 28 and 29, which extend in or on the compressed air lines 13 and 14 and for instance are constitute by a wire braid structure, or metal foil, embedded in a casing of the compressed air lines 13 and 14 or extending on same. Furthermore, as an electrical conductor in the compressed air lines 13 and 14 furthermore one or more metal multi-strand wires or cables may be provided. The electrical contact between the connecting lines 28 and 29 and the actuator 10 and furthermore the valve arrangement 12 is produced by way of connections 15 through 18, which in the present case consist of metal and accordingly are electrically conductive. The connections 15 through 18 are in electrical contact with the compressed air lines 13 and 14, such contact being produced f. i. by knife contact elements, which cut into the compressed air lines 13 and 14.
 During assembly of the connections 15 through 18, for example by screwing or plugging into one another, in the present case a single manipulation produces both a fluid and also an electrical connection between the valve arrangement 12 and the actuator 10. In principle it would be possible to provide separate electrical contact elements, separate from the connections 15 through 18, and independent from the respective fluid power connection for connection of the electrical connection lines 28 and 29 with the valve arrangement 12 and, respectively, the actuator 10.
 The valve arrangement 12 possesses an electrical energy source 30, which by way of electrical connections 31 and 32 and by way of the connections 15 and 16 is connected with the electrical connection lines 28 and 29. The energy source may for example be one member of a voltage converting component group which is supplied from an external voltage source, not illustrated. The energy or power source 30 provides a voltage UV for the actuator 10 by way of the electrical connection lines 28 and 29.
 For using the voltage UV the actuator 10 possesses an energy converter 33, which by way of electrical connections 34 and 35 and by way of the connections 17 and 18 is connected with the electrical connection lines 28 and 29. The energy converter 33 converts the voltage UV, for example with the aid of an electronic circuit and/or an electrical transformer, a rectifier and a smoothing capacitor and supplies a current distribution system 36, only indicated by a positive potential and a negative potential, of the actuator 10.
 On the actuator 10 sensors 37 and, respectively, 38 designed in the form of electrical components, are provided, which are associated with the respective cylinder spaces 24 and 26. The sensors 37 and 38 detect an operational state of the actuator 10 in the present case the position of the piston 27, and indicate this to a control module 39, which controls the valve arrangement 12 and the actuator 10. The sensors 37 and 38 are f. i. limit switches actuated by the piston 27. The sensors 37 and 38 may however f. i. also be sensors operating ultrasonically which as components of a displacement measuring system ascertain the position of the piston 27. On the actuator 10 it would be possible for instance to also provide temperature sensors, pressure sensors or other sensors for detecting a regular operational state and/or a trouble state.
 The actuator 10 supplies values ascertained by the sensors 37 and 38 to the control module 39, which in the working embodiment of FIG. 1 constitutes a component of the valve arrangement 12. The control module 39 comprises for instance microprocessor, memory means and an input/output interface. The control module 39 functions in accordance with a pre-programmed functional profile, which is set by a program code stored in the memory means and by way of a control connection 48 controls the valve 19 and accordingly the actuator 10. The control module 39 could also be an analog and/or digital regulating circuit. The control module 39 can receive instructions from a control console, not illustrated, and/or a central master control, not illustrated.
 The values detected by the sensors are supplied to the control module 39 by way of a signal connection SV indicated in chained lines, contained in the electrical connection lines 28 and 29. For the production of the signal connection SV a communication module 41 is provided in the actuator 10 as a signal producing and/or signal detecting means, such communication module serving as a communication means and being coupled to the connections 34 and 35, for example using an electrical transmitter. Accordingly it is connected with the electrical connection lines 28 and 29. The communication module 41 receives data, detected by the sensors 37 and 38, by way of connections 42 and 43. The same are employed by the communication module 41 as monitoring signals with the aid of a modulator for modulation of the voltage UV. For this purpose pulse width, pulse frequency or some other modulation method is utilized. It is also possible for the communication module 41 to digitally encode the monitoring signals using an encoding means and to transmit same as serial data telegrams to the valve arrangement 12. For this purpose a field bus protocol can for example be utilized.
 For receiving the monitoring signals on the signal connection SV the valve arrangement 12 comprises a communication module 44 which is coupled with the connections 31 and 32, for example by way of a shunt resistor connected in series with the energy source 30 and spies on, as it were, the modulated and/or encoded monitoring signal transmitted by way of the electrical connections 28 and 29 and with the aid of a demodulator and/or decoder detects the voltage UV. The communication module 42 transmits the monitoring signals by way of a connection 45 to the control module 39 with the result that in all the signal connection SV is produced between the sensors 37 and 38 and the control module 39.
 The control module 39 controls the valve 19 in a manner dependent on the respective monitoring signals from the sensors 37 and 38, which contain information about the position of the piston 27. In this case the cylinder space 26 is for example only pressurized with compressed air until the sensor 37 indicates that the piston 27 has reached its terminal position in the cylinder head.
 The actuator 10 in the working example possesses as a further electrical component a display element 46. The display element 46 comprises for example LED's and/or a LCD display module for displaying the current operational states, for instance the current position of the piston 27 and/or to indicate trouble conditions, for example when a component of the actuator 10 is defective or has completely failed.
 The display element 46 is connected by way of an electrical connection 47 with the communication module 41 and via same receives control instructions from the control module 39. Using a modulator the communication module 44 then modulates the voltage UV with control signals which are recovered again by the communication module 41 by means of a demodulator. The modulator is for example coupled by means of an electrical transmitter with an electrical connections 31 and 32. The demodulator scans, for example using a resistor connected in series with the energy converter 33, the voltage changes caused by the control signals with which the voltage UV is modulated.
 In principle the modulator in the communication module 44 could also modulate the voltage UV, and for example by switching on and off the voltage UV could form a digital pulse sequence.
 The actuator 10 could as an electrical component also possess an electrical drive means, controlled by the control module 39, as for example an electromagnetic drive or a drive motor. Furthermore, operating elements could be provided on the actuator 10, as for instance an “emergency off” switch, which send instructions of an operator by way of the communication module 42 and the electrical connection lines 28 and 29 to the control module 39.
FIG. 2 shows valve arrangements 12 a and 12 b, which are connected with actuators 10 a and 10 b, respectively, by way of compressed air lines 13 a, 14 a and, respectively, 13 b and 14 b. The valve arrangements 12 a and 12 b are modules of a valve cluster 60, which is supplied with compressed air by way of the compressed air supply line 22 illustrated in FIG. 1, and is controlled by a central control module 61 by way of a bus 63, for example an AS-i field bus (AS-i denoting actuator sensor interface). The bus 63 and furthermore the compressed air supply line 22 symbolically representing a compressed air distribution system, not illustrated, are extended through the valve arrangements 12 a and 12 b so that further valve arrangements, in the form of modules and not illustrated to make the figure more straightforward, can be lined up on the valve cluster 60. The control module 61 can constitute a separate control device or form a component of the valve cluster 60.
 The actuators 10 a and 10 b are essentially the same in structure as the actuator 10 in accordance with FIG. 1, but however lack the display element 46. Moreover the valve arrangements 12 a and 12 b are essentially the same in structure as the valve arrangement 12. Identical or identically functioning components are therefore in FIG. 2 provided with the same reference numerals as the corresponding component in FIG. 1, added small case letters “a” and “b” indicating an association of the respective component with the actuator valve arrangement combinations 10, 12 a and, respectively, 10, 12 b.
 In contradistinction to the valve arrangement 12 the valve arrangements 12 a and 12 b however lack any separate control module of their own and instead of this are connected by way of bus interface modules 64 a and 64 b with the field bus 63 and are controlled via same by the control module 61. The bus interface modules 64 a and 64 b and the communication modules 44 a and 44 b respectively associated with them can be respectively put in a component group, for example an IC.
FIG. 3 essentially shows the arrangement in accordance with FIG. 1. In contradistinction to FIG. 1 however only one electrical connection is provided between the valve arrangement 12 and the actuator 10 by way of an electrically conductive compressed air line, namely the compressed air line 13. The second electrical connection between the valve arrangement 12 and the actuator 10 is by way of common ground potential MP, for example a common grounding means, to the electrically conductive connections 16 and 19 in each case. It is also possible for the housing of the actuator 10 and the valve arrangement 12 to be respectively connected with the ground potential MP with the result that the second electrical connection is made. In a fluid connecting compressed air line 14 c joining the connections 16 and 18 consequently, unlike the compressed air line 14, no electrical line is required.
 It is also possible for the actuators 10 a and 10 b to only have controlled electrical components, as for example electrical drive members, or only monitoring components, as for instance sensors.
 A particularly simple and merely diagrammatically illustrated modification of the working example in accordance with FIG. 1 is depicted in FIG. 4, in the case of which signal producing means of the actuator set impressed current flows on the signal connection leading to the valve arrangement. However, for simplification of the drawing only a few components of the actuator 10 and of the valve arrangement 12 are depicted. The energy source 30 of the valve arrangement 12 supplies by way of the electrical connections 28 and 29 (which are by way of the compressed air line 13 and 14) the actuator 10 with the voltage UV, which drops at the sensors 37 and 38 connected in parallel with the electrical connections 34 and 35, and at current sources 50 and 51 respectively connected in series therewith, such current sources serving as signal producing means. The sensors 37 and 38 are for example reed switches, magnetostrictive elements or hall sensors, which become electrically conductive in the proximity of the piston 27 and are otherwise non-conductive or have a low conductivity. The current sources 50 and 51 are so-called current flow setting diodes which in their conductive direction are conductive as far as a predetermined current flow, that is to say they set an impressed current flow. It is also possible for the current sources 50 and 51 to be constituted by transistor circuits, which set an impressed current flow or for the sensors 37 and 38 to inherently set current flows impressed by their respective resistance value and accordingly as such constitute the signal producing means of the actuator 10.
 When the sensors 37 and 38, owing to the proximity of the piston 27, become electrically conductive, they will carry current flow, which is set by the current sources 50 and 51 respectively set as the impressed current I37 and, respectively, I38. The values of the current flows I37 and I38 have different levels so that an overall current flow Iges flowing the electrical connections 28 and 29 is set with the values Iges=0, Iges=I37, Iges=I38 or, more particularly in the case of a fault, Iges=I 37+I38. The level of the overall current Iges is accordingly a signal determined by the signal producing means of the actuator 10 for the respective position of the piston 27.
 In the valve arrangement 12 there is a shunt resistor 52, which is connected in series with the energy source 30 and associated with the signal detection means of the valve arrangement 12 having a resistance R, a so-called shunt, which has the overall current Iges flowing through it and at which, in accordance with the overall current Iges, a voltage Um drops with the values Um=0, Um R * I37, Um R * I38 or Um R * (I37+I38). The level of the voltage Um is scanned and evaluated using signal detection means not illustrated in detail.
 It will be clear that the principle indicated in FIG. 4, in the case of which the impressed current flows are set, may also be employed in the reverse direction for supplying a signal from the valve arrangement 12 to the actuator 10.
 Furthermore as a signal producing means instead of the current sources 50 and 51 or in addition thereto a respective resistor could be provided, such resistors preferably having different resistance values. Moreover, the sensors 37 and 38 could respectively produce different resistance values, for instance owing to the proximity of the piston 27 in the electrically connecting state with the result that the sensors 37 and 38 could serve as signal producing means.
 Further designs are readily possible.
 To the extent that an actuator only comprises monitoring electrical components, only transmitting means, as for example a modulator will be necessary in its communication module, as for example a modulator, and in the valve arrangement associated with the actuator or in the control module associated with it only receiving means, as for example a demodulator, will be necessary.
 If an actuator only contains controlled electrical components and no monitoring ones, then in the communication module associated with the actuator only a transmitting means, as for example a modulator, and in the actuator only a receiving means, as for example a demodulator, will be necessary.
 If however an actuator and a valve arrangement communicate bi-directionally, as for instance using a field bus protocol, then in their respective communication modules both transmitting and also receiving means will be required independently of whether the respective actuator has only controlled or only monitoring electrical components. By way of a bi-directional connection the respective control module can control information flow and for instance perform diagnosistic interrogation on the actuator.
 In accordance with a modification of the arrangement of FIG. 2 the communication modules 44 a and 44 b and furthermore the energy sources 30 are not integrated in the valve arrangements 12 a and arrangements 12 b and instead constitute a component of the control module 61. The electrical connection lines 28 a, 29 a, 29 a and 29 b would then pass through the valve arrangements 12 a and 12 b and be connected with the control module 61, for instance by way of a parallel bus between the control module 61 and the valve arrangements 12 a and 12 b.
 In accordance with a further development of the invention the bus interface modules 64 a and 64 b and the communication modules 44 a and 44 b associated with them could be arranged together as a separate sub-assembly, which could for example be arranged on a valve cluster or on a control module.
 The connections 42 and 43 for the sensors 37 and 38 are wired or wireless connections. The sensors 37 and 38 would be designed as so-called transponders, for example, in the case of wireless connections.
 The electrical components of the actuator 10, for instance the communication module 42 and the energy converter 33 may be at least in part arranged together as a common sub-assembly. Same can for example be arranged on the cylinder 11, for instance in a head of the cylinder 11.
 In the illustrated working examples the compressed air lines 13 and 14 respectively have but one single electrical conductor. It is however also possible in principle to have further electrical conductors for other purposes.
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|International Classification||F15B21/08, F15B9/09|
|Cooperative Classification||F15B13/0867, F15B9/09, F15B21/08|
|European Classification||F15B21/08, F15B9/09, F15B13/08B10L|
|Apr 7, 2003||AS||Assignment|
Owner name: FESTO AG & CO., GERMANY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEDERER, THOMAS;ZIEGELE, ACHIM;AICHELE, ALEXANDER;REEL/FRAME:014349/0244
Effective date: 20030401