Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus interface architecture
Reexamination Certificate
1999-07-20
2002-09-24
Dharia, Rupal (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus interface architecture
C713S300000
Reexamination Certificate
active
06457088
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to adjustable devices, such as amplifiers for example, which convert a command signal to an appropriate control signal in order to control a mechanism according to parameters stored in the amplifier. More specifically, the present invention relates to a method and apparatus for modifying parameters of a valve amplifier such that it achieves the desired command-signal-to-control-signal conversion for controlling a valve.
BACKGROUND OF THE INVENTION
Proportional solenoid valves are typically controlled by a valve amplifier, wherein an input command signal from a controller causes magnetically actuated movement of a slidable member in the valve, causing a flow path in the valve to become more open or more closed, thereby affecting fluid flow. This input command signal from the controller is usually a voltage signal between 0 and 10 volts, 0 volts corresponding to no flow and 10 volts corresponding to full flow. An example of a solenoid valve is provided in U.S. Pat. No. 5,242,149, the entire disclosure of which is hereby incorporated herein by reference.
However, a solenoid valve cannot respond directly to this voltage command, because each valve requires an electrical current which is between its minimum electrical current value (e.g., no flow) and its maximum electrical current value (e.g., maximum flow). Thus, in order for the valve to operate, a conversion device, such as an amplifier for example, is required to convert the voltage command signal from the controller to the appropriate electrical current control signal for the valve. For example, a voltage command signal which represents 50% flow (e.g., a 5 volt command signal) needs to be converted to the appropriate electrical current by the valve amplifier. In other words, the amplifier provides a control signal to the valve which is proportional to the input command signal. An example of such an amplifier is the PVG mobile valve amplifier, manufactured by Danfoss Fluid Power.
Valve amplifiers have also had the capability to be modified for the particular controller and valve with which they will be used. Parameters which affect the voltage-command-signal-to-electrical-current-control-signal conversion can include the ramp time, deadband, gain, maximum amplitude, and dither frequency, for example. The parameters are adjusted according to the particular valve with which the amplifier is used, and the particular application in which the valve is used.
For some amplifiers, the parameters can be adjusted by adjusting potentiometers provided in the amplifier circuitry. However, if the amplifier is digitally programmable, the amplifier can be provided with a connector, such as a serial connector, which can connect the programmable digital controller within the amplifier to a personal computer (PC) or other digital programming apparatus. Software on the PC can then adjust the parameters which affect the voltage-command-signal-to-electrical-current-control-signal conversion. Parameters can be downloaded from the PC to the amplifier, or uploaded from the amplifier to the programming apparatus and stored in a file. An example of such a programmable amplifier is described in U.S. Pat. No. 5,638,863, the entire disclosure of which is hereby incorporated herein by reference. Such an amplifier is described in the patent as including a microcomputer, a memory, and a separate interface for connecting to an external personal computer. When the computer is connected to the microcomputer through the interface, new parameters can be written to the memory of the amplifier.
Another example of a programmable or adjustable amplifier is available under the trade name EMA amplifier, which is manufactured by Vickers Incorporated for controlling the EMV-611e valve. Windows-based software can be used for setting parameters and showing amplifier status via a PC, which can be connected using a serial connector on the amplifier. The software on the PC digitally sets ramp, deadband, gain and dither, which can be saved by a filename and recalled and used for various machine types. This amplifier requires a separate interface for receiving the command signal input from a controller.
Another programmable amplifier which has been developed is described in U.S. Pat. No. 5,172,311, issued to Reinhart et al. This amplifier includes a programmable component including a read-only-memory in which the amplifier is associated to a particular type of valve by loading the read-only-memory with valve specific data which specify a valve type. The programmable component of the amplifier comprises a microprocessor, a random access memory, and a separate interface for series transfer of data to and from a computer. Data transmitted through the interface to program the amplifier is stored in the random access memory.
However, while the programmable capability of such amplifiers can be advantageous, such amplifiers require an extra connector or interface for connecting to the programming apparatus (e.g., a computer). In addition, they require various components to allow the amplifier to communicate with the programming apparatus. As can be understood, this extra hardware adds to the cost of the amplifier and its complexity, and also takes up additional space. Moreover, the additional connector can compromise the environmental seal of the amplifier, which often needs to meet demanding standards.
Accordingly, it is desirable to provide a method and apparatus for programming parameters of a programmable device without requiring the device to include a separate interface, other than the interface which is already used to receive command signals, such that cost and complexity of the device are not increased, and the environmental rating is not compromised. Moreover, it is desirable to provide a method and apparatus for programming parameters of a programmable device without the necessity of providing the device itself with the programming components, which can add to its cost and complexity. Preferably, the programmable device can comprise an amplifier, such as a valve amplifier for example, which can convert a command signal to an appropriate control signal, for control of a controllable mechanism, such as a valve for example.
SUMMARY OF THE INVENTION
It is an object of the present invention to obviate the above-described problems.
It is a further object of the present invention to provide a method and apparatus for programming a programmable or adjustable device, such as a valve amplifier for example, without the necessity of providing the device with a separate interface for connection to a programming apparatus, such as a personal computer or microcontroller for example.
Yet another object of the present invention is to provide a method and apparatus for programming a device, without the necessity of providing the device with additional programming components.
Another object of the present invention is to provide a method and apparatus for connecting a valve amplifier to a computer, or other programming apparatus, without the necessity of providing the amplifier with an additional input connector.
It is yet another object of the present invention to provide a method and apparatus for programming a valve amplifier while providing the amplifier with a good resistance to environmental contaminants.
It is a further object of the present invention to provide an apparatus for programming a valve amplifier without the necessity of a personal computer or other digital programming device and without the necessity of providing the amplifier with a separate input connector/interface.
Another object of the present invention is to provide a valve amplifier adapter which can be connected to a valve amplifier when programming of the amplifier is required, but which can be removed from the amplifier when the amplifier is to control a valve.
Yet another object of the invention is to provide a method for programming a valve amplifier which does not require the amplifier to include a separate connection for the programming apparatus.
It is
Dharia Rupal
Dinsmore & Shohl LLP
Vickers, Inc.
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