EP0149010A2
Expired / Lapsed
EP
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Digital fluid pressure flow rate and position control system
Assignee: Digital Hydraulics Inc
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Filing: 1984-10-03
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Granted: —
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Expires: 2004-10-03
Abstract
Abstract A control valve or system of control valves governs fluid flow by digitally comparing a feedback signal from a fluid control loop with a command signal corresponding to a desired flow rate in a high pressure operating fluid flow line. In the preferred embodiment, a control valve system, such as a pressure relief valve, is operated under the control of a digital computer. The pressure relief valve is operated at a control pressure to regulate flow in an operating hydraulic system. The control pressure chamber is coupled to a relief line through a control pressure reduction valve and to a control pressure enhancement valve which is in communication with the operating line of fluid flow. A feedback signal indicating actual control pressure, flow rate or load position is compared with a command control pressure, flow rate or position. Preferably, the results of several comparisons are averaged together to provide an error correction signal. The error correction signal selectively actuates the pressure enhancement and pressure reduction valves to maintain the desired control pressure, flow rate or load position. The system preferably includes a deactuating means which limits actuation of the control pressure enhancement and reduction valves to the duration of pulses of a width related to the magnitude of the error correction signal.
Inventors
- 👤 Raymond D. Woodworth
- 👤 James F. Stoutamore
- 👤 Philip S. Vanderhoek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 22:40
CPC Classifications
G; G05; G05D; G05D7/00; G05D7/06; G05D7/0617; G05D7/0629; G05D7/0635; G05D16/00; G05D16/20; G05D16/2093; G05D16/2097; Y; Y10; Y10T; Y10T137/00; Y10T137/2278; Y10T137/2409; Y10T137/7722; Y10T137/7758; Y10T137/7761
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
251 words
In a fluid flow control system including a fluid control valve having a first port, a second port, a moveable closure element interposed therebetween operated by fluid at a control pressure and in communication with said first port, the improvement comprising a relief line, a control pressure enhancement valve in flow communication with said first port, a control pressure reduction valve in fluid communication with said control pressure enhancement valve and said relief line, a control pressure enhancement solenoid coupled to operate said control pressure enhancement valve a control pressure reduction solenoid coupled to operate said control pressure reduction valve, a signal generating means for selectively actuating said control pressure enhancement and control pressure reduction solenoids, a command signal source for providing a command control pressure signal corresponding to a desired flow rate between said first and second ports, a control pressure feedback transducer coupled in line between said control pressure enhancement and reduction valves to provide a feedback signal indicative of actual pressure in line therebetween, comparator means coupled to receive.and compare said command control pressure signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control pressure signal and said feedback signal, thereby causing said signal generating means to responsively select one of said solenoids and activate it for a period of time related to the magnitude of difference between said command control pressure signal and said feedback' signal.
Claim 2
Dependent Claim
251 words
In a fluid flow control system including a fluid control valve having a first port, a second port, a moveable closure element interposed therebetween operated by fluid at a control pressure and in communication with said first port, the improvement comprising a relief line, a control pressure enhancement valve in flow communication with said first port, a control pressure reduction valve in fluid communication with said control pressure enhancement valve and said relief line, a control pressure enhancement solenoid coupled to operate said control pressure enhancement valve a control pressure reduction solenoid coupled to operate said control pressure reduction valve, a signal generating means for selectively actuating said control pressure enhancement and control pressure reduction solenoids, a command signal source for providing a command control pressure signal corresponding to a desired flow rate between said first and second ports, a control pressure feedback transducer coupled in line between said control pressure enhancement and reduction valves to provide a feedback signal indicative of actual pressure in line therebetween, comparator means coupled to receive.and compare said command control pressure signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control pressure signal and said feedback signal, thereby causing said signal generating means to responsively select one of said solenoids and activate it for a period of time related to the magnitude of difference between said command control pressure signal and said feedback' signal.
Claim 3
Dependent Claim
36 words
The fluid flow control system of Claim 1 in which said signal generating means is digitally activated, said comparator is a digital comparator, and said control pressure command signal and said feedback signals are digitized signals.
Claim 4
Dependent Claim
81 words
The fluid flow control system of Claim 1 f urther.comprising a signal terminating means coupled to said command signal source said control pressure feedback transducer and said signal generating means to monitor the difference between said command control pressure signal and said feedback signal following activation of said signal generating means and to deactivate said signal generating means when the difference between said command control pressure signal and said feedback signal diminishes to a predetermined portion of said error correction signal.
Claim 5
Dependent Claim
240 words
A digitally controlled fluid flow control system comprising: a fluid inlet line, a fluid outlet line, a load bypass line, a flow control pressure amplification valve means coupled to said fluid inlet line and,defining a path leading therefrom to said load bypass line, , a pilot pressure enhancement valve coupled to said flow control pressure amplification valve means and in fluid communication with one of said fluid inlet and outlet lines, a pilot pressure reduction valve coupled between said flow control pressure amplification valve means and a fluid relief line, a pressure enhancement solenoid coupled to operate said pilot pressure enhancement valve, a pressure reduction solenoid coupled to operate said pilot pressure reduction valve, digital pulse generating means for pulsing said pressure enhancement and pressure reduction solenoids with electronic signals of a controlled duration, a command signal source for providing a first electrical signal indicative of desired rate of fluid flow from said inlet line to said outlet line, a pilot pressure transducer coupled to provide a second signal indicative of pilot pressure between said pressure enhancement and reduction valves and said flow control pressure amplification valve means, signal processing means for comparing said first and second electrical signals and for providing an error correction signal dependent upon the difference between said first and second signals to said pulse generating means to pulse a selected one of said pressure enhancement and pressure reduction solenoids for a corresponding duration of time.
Claim 6
Dependent Claim
240 words
A digitally controlled fluid flow control system comprising: a fluid inlet line, a fluid outlet line, a load bypass line, a flow control pressure amplification valve means coupled to said fluid inlet line and,defining a path leading therefrom to said load bypass line, , a pilot pressure enhancement valve coupled to said flow control pressure amplification valve means and in fluid communication with one of said fluid inlet and outlet lines, a pilot pressure reduction valve coupled between said flow control pressure amplification valve means and a fluid relief line, a pressure enhancement solenoid coupled to operate said pilot pressure enhancement valve, a pressure reduction solenoid coupled to operate said pilot pressure reduction valve, digital pulse generating means for pulsing said pressure enhancement and pressure reduction solenoids with electronic signals of a controlled duration, a command signal source for providing a first electrical signal indicative of desired rate of fluid flow from said inlet line to said outlet line, a pilot pressure transducer coupled to provide a second signal indicative of pilot pressure between said pressure enhancement and reduction valves and said flow control pressure amplification valve means, signal processing means for comparing said first and second electrical signals and for providing an error correction signal dependent upon the difference between said first and second signals to said pulse generating means to pulse a selected one of said pressure enhancement and pressure reduction solenoids for a corresponding duration of time.
Claim 7
Dependent Claim
113 words
A digitally controlled fluid flow system according to Claim 4 further comprising a load pressure transducer coupled to said signal processing means to provide a third electrical signal indicative.of actual load supply pressure from said inlet line to said outlet line, means in said signal processing means for storing a predicted proportional relationship between said second and third signals, means in said signal processing means for applying said proportional relationship to one of said second and third signals to produce a scaled signal and for comparing said scaled signal to the other of said second and third signals, and means for providing an indication of inequivalenceof said scaled signal and said other signal.
Claim 8
Dependent Claim
45 words
A digitally controlled fluid flow system according to Claim 5 further comprising means for storing a tolerance value and means for suppressing the indication of inequivalence between said scaled signal and said other signal if the extent of inequivalence is less than said tolerance level.
Claim 9
Dependent Claim
60 words
7 . A digitally controlled fluid flow system according to Claim 4 further comprising a limit signal source to provide a limit signal to said signal processing means indicative of an upper allowable limit of said second signal, and means for comparing said first signal with said limit signal and for providing the smaller thereof as said first digital signal.
Claim 10
Dependent Claim
53 words
A digitally controlled fluid flow system according to Claim 4 further comprising an error correction signal comparison means to compare said error correction signal' with a threshold value and to suppress transmission of said error correction signal to said pulse generating means when said error correction signal is smaller than said threshold value.
Claim 11
Dependent Claim
64 words
A digitally controlled fluid flow system according to Claim 4 further comprising averaging means for receiving said error correction signal, and for iteratively triggering the generation of a subsequent error correction signal, for averaging together a predetermined number of sequentially generated error correction signals and thereafter treating the average of said predetermined number of sequentially generated error correction signals as said error correction signal.
Claim 12
Dependent Claim
91 words
A digitally controlled fluid flow system according to Claim 4 in which said error correction signal actuates said digital pulse generating means and further comprising a deactuating means for receiving said error correction signal and for thereafter iteratively sampling said first and second signals and for iteratively comparing said first and second signals to produce an error signal, and for iteratively comparing said error signal with said error correction signal and for deactuating said pulse generating means when said error signal diminishes to a predetermined portion of said error correction signal.
Claim 13
Dependent Claim
60 words
A digitally controlled fluid flow system according to Claim 10 in which said deactuating means include averaging means for receiving said error signal, and for iteratively triggering the generation of sequential error signals, for averaging together a predetermined number of sequentially generated error signals and thereafter treating the average of said predetermined number of error signals as said error signal.
Claim 14
Dependent Claim
251 words
In a pressure relief valve system having a flow inlet, a flow outlet, and a flow bypass, and a pressure relief valve means which diverts flow from said inlet to said flow bypass in a volume governed by a control pressure, the improvement comprising a control pressure enhancement valve coupled to said pressure relief valve means and in flow communication with one of said. flow inlet and flow outlet, a control pressure reduction valve coupled between said pressure relief valve means and a relief line, a pressure enhancement solenoid coupled to operate said control pressure enhancement valve, a pressure reduction solenoid coupled to operate said control pressure reduction valve, digitally activated signal generating means for selectively actuating said pressure enhancement and pressure reduction solenoids, a command signal source for providing a command control pressure signal corresponding to a desired flow rate from said inlet to said outlet, a feedback transducer coupled to provide a feedback signal indicative of actual control pressure from said pressure relief valve, and digital comparator means coupled to receive and compare said command control pressure signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control pressure signal and said feedback signal, whereby said signal generating means responsively selects one of said solenoids and actuates it for a period of time related to the magnitude of difference between said command control pressure signal and said feedback signal.
Claim 15
Dependent Claim
251 words
In a pressure relief valve system having a flow inlet, a flow outlet, and a flow bypass, and a pressure relief valve means which diverts flow from said inlet to said flow bypass in a volume governed by a control pressure, the improvement comprising a control pressure enhancement valve coupled to said pressure relief valve means and in flow communication with one of said. flow inlet and flow outlet, a control pressure reduction valve coupled between said pressure relief valve means and a relief line, a pressure enhancement solenoid coupled to operate said control pressure enhancement valve, a pressure reduction solenoid coupled to operate said control pressure reduction valve, digitally activated signal generating means for selectively actuating said pressure enhancement and pressure reduction solenoids, a command signal source for providing a command control pressure signal corresponding to a desired flow rate from said inlet to said outlet, a feedback transducer coupled to provide a feedback signal indicative of actual control pressure from said pressure relief valve, and digital comparator means coupled to receive and compare said command control pressure signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control pressure signal and said feedback signal, whereby said signal generating means responsively selects one of said solenoids and actuates it for a period of time related to the magnitude of difference between said command control pressure signal and said feedback signal.
Claim 16
Dependent Claim
61 words
In a pressure relief valve system according to Claim 12 the further improvement comprising means coupled to said digital comparator for averaging consecutive samples of said digitized command control pressure and feedback signals over a predetermined number of iterations to generate said digital error correction signal as the arithmetic mean of differences between said digitized command control pressure and feedback signals-
Claim 17
Dependent Claim
98 words
In a pressure relief valve system according to Claim 12 the further improvement comprising digitally activated solenoid deactuating means for deactuating the solenoid actuated by said signal generating means, and digital calculating means coupled to receive the digital error correction signal which activates said signal generating means and for, thereafter, iteratively measuring said command control pressure signal and said feedback signal, computing the difference therebetween as an error signal, comparing said error signal with said error correction signal, and activating said solenoid deactuating means when said error signal diminishes to a predetermined portion of said error correction signal.
Claim 18
Dependent Claim
59 words
In a pressure relief valve system according to Claim 14 the further improvement in which said solenoid deactuating means includes means for averaging consecutive samples of said digitized command control pressure and feedback signals over a-second predetermined number of iterations to generate said error signal as the arithmetic means of differences between said command control pressure and feedback signals.
Claim 19
Dependent Claim
40 words
In a pressure relief valve system according to Claim 12 the further improvement comprising threshold testing means which allows said digital comparator means to activate said signal generating means only if said error correction signal achieves a predetermined threshold magnitude.
Claim 20
Dependent Claim
40 words
In a pressure relief valve system according to Claim 12 the further improvement comprising command control pressure signal limiting means coupled to said digital comparator means to limit the value of said command control pressure signal to a predetermined maximum.
Claim 21
Dependent Claim
251 words
In a fluid flow control system including a flow control valve having a first port, a second port, a moveable closure element interposed therebetween operated by fluid at a control pressure and in communication with said first port, the improvement comprising a relief line, a control pressure enhancement valve in flow communication with said first port, a control pressure reduction valve in fluid communication with said control pressure enhancement valve and said relief line, a control pressure enhancement solenoid coupled to operate said control pressure enhancement valve, a control pressure reduction solenoid coupled to operate said control pressure reduction valve, a signal generating means for selectively actuating said control pressure enhancement and control pressure reduction solenoids, a command signal source for providing a command control signal corresponding to a desired flow rate between said first and second ports, a feedback transducer coupled in communication with at least one of said first and second ports- to--provide a feedback signal indicative of movement of ,fluid between said first and second ports, comparator means coupled to receive and compare said command control signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control signal and said feedback signal, thereby causing said signal generating means to responsively select one of said solenoids and activate it for a period of time related to the magnitude of difference between said command control signal and said feedback signal.
Claim 22
Dependent Claim
251 words
In a fluid flow control system including a flow control valve having a first port, a second port, a moveable closure element interposed therebetween operated by fluid at a control pressure and in communication with said first port, the improvement comprising a relief line, a control pressure enhancement valve in flow communication with said first port, a control pressure reduction valve in fluid communication with said control pressure enhancement valve and said relief line, a control pressure enhancement solenoid coupled to operate said control pressure enhancement valve, a control pressure reduction solenoid coupled to operate said control pressure reduction valve, a signal generating means for selectively actuating said control pressure enhancement and control pressure reduction solenoids, a command signal source for providing a command control signal corresponding to a desired flow rate between said first and second ports, a feedback transducer coupled in communication with at least one of said first and second ports- to--provide a feedback signal indicative of movement of ,fluid between said first and second ports, comparator means coupled to receive and compare said command control signal and said feedback signal to provide an error correction signal to said signal generating means dependent upon the magnitude of difference and indicative of the larger of said command control signal and said feedback signal, thereby causing said signal generating means to responsively select one of said solenoids and activate it for a period of time related to the magnitude of difference between said command control signal and said feedback signal.
Claim 23
Dependent Claim
19 words
.19. The fluid flow control system of Claim 18 in which said feedback transducer is a flow rate transducer.
Claim 24
Dependent Claim
17 words
The fluid flow control system of Claim 18 in which said feedback transducer is a position sensor.
References Cited (Backward Citations)
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