Hydraulically operated linear actuator and an electrical control system
First Claim
1. A needle bar shifter for selectively positioning a transversely slidable needle bar of a textile turting machine comprising a housing mounted on said machine, an operating rod reciprocally mounted in and projecting from said housing for transverse movement in alignment with and connected to said slidable needle bar for transverse positioning thereof, said housing having a linearly extending piston chamber in which said operating rod reciprocates and a return chamber separate from said piston chamber through which said operating rod reciprocates, an intake port formed in said housing and communicating with said piston chamber for introduction of pressurized hydraulic fluid thereinto and a discharge port formed in said housing and communicating with said return chamber for discharge of hydraulic fluid therefrom, said operating rod having a piston formed thereon in said piston chamber in sealing disposition for reciprocation therein at a spacing from said intake port, said operating rod having a linearly extending bore therein opening into the portion of said piston chamber opposite said intake port and communicating with said return chamber, a control spool sealingly disposed in said bore for sliding therein, said operating rod having a drive passage therethrough for passage of pressurized hydraulic fluid from the portion into which said intake port opens to said opposite portion to drive said piston in a direction to expand said opposite portion, one of said operating rod and said control spool having a return passage therein opening into and extending between said bore and said opposite portion of said piston chamber for flow of hydraulic fluid to said return chamber upon movement of said piston in a direction to contract said opposite portion, said spool being selectively positionable in closing relation to either one or both passages to selectively permit flow of hydraulic fluid through one or the other or neither of said passages, said piston having an effective surface area in said opposite portion of said piston chamber for application of pressurized hydraulic fluid to cause piston movement in the direction of said intake port sufficiently larger than the effective surface area in said intake port portion so that upon movement of said spool from a disposition closing both passages in a direction to open said drive passage the pressurized hydraulic fluid passing therethrough will act on said piston to move said operating rod into passage closing relation to said spool and upon movement of said spool in the opposite direction said return passage will be opened allowing fluid to pass from said opposite portion of said piston chamber to said return chamber and thereby allowing the pressurized fluid in said intake port portion to move said operating rod in the opposite direction into passage closing relation to said spool, and means for selectively positioning said spool to open one or the other of said passages and thereby cause responsive movement of said operating rod by unbalanced application of pressurized hydraulic fluid to said piston with a corresponding movement of said needle bar.
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Accused Products
Abstract
A needle bar shifter for a textile tufting machine having an operating rod connected to the needle bar and extending into an hydraulic cylinder for manipulation by movement of a spool in a bore in the rod, the rod having passages to permit flow of hydraulic fluid from one side to the other of the end of the rod by opening of different passages by movement of the spool, which is manipulated by light hydraulic pressure independent of the high pressure needed for manipulation of the rod and needle bar. An electrical system for controlling manipulation of the spool includes a plug board for predesignating a pattern of individual sequential positions of the needle bar, which positions are indicated by electrical signals generated in response to scanning of the plug board and compared with signals indicating the preexisting position of the spool, with the system limiting the resultant control signal to a preset maximum magnitude so that the rod will be manipulated in steps to the predesignated position, and when no plug is present in a plug row being scanned the system will randomly select a signal to produce a resultant control signal, which is limited as aforesaid in magnitude. A split phase amplifier compares the magnitudes of the resultant control signal and a signal indicating the preexisting position of the spool to produce a polarity indication of the direction of needle bar movement to be effected and permitting individual gain control for each polarity.
33 Citations
37 Claims
- 1. A needle bar shifter for selectively positioning a transversely slidable needle bar of a textile turting machine comprising a housing mounted on said machine, an operating rod reciprocally mounted in and projecting from said housing for transverse movement in alignment with and connected to said slidable needle bar for transverse positioning thereof, said housing having a linearly extending piston chamber in which said operating rod reciprocates and a return chamber separate from said piston chamber through which said operating rod reciprocates, an intake port formed in said housing and communicating with said piston chamber for introduction of pressurized hydraulic fluid thereinto and a discharge port formed in said housing and communicating with said return chamber for discharge of hydraulic fluid therefrom, said operating rod having a piston formed thereon in said piston chamber in sealing disposition for reciprocation therein at a spacing from said intake port, said operating rod having a linearly extending bore therein opening into the portion of said piston chamber opposite said intake port and communicating with said return chamber, a control spool sealingly disposed in said bore for sliding therein, said operating rod having a drive passage therethrough for passage of pressurized hydraulic fluid from the portion into which said intake port opens to said opposite portion to drive said piston in a direction to expand said opposite portion, one of said operating rod and said control spool having a return passage therein opening into and extending between said bore and said opposite portion of said piston chamber for flow of hydraulic fluid to said return chamber upon movement of said piston in a direction to contract said opposite portion, said spool being selectively positionable in closing relation to either one or both passages to selectively permit flow of hydraulic fluid through one or the other or neither of said passages, said piston having an effective surface area in said opposite portion of said piston chamber for application of pressurized hydraulic fluid to cause piston movement in the direction of said intake port sufficiently larger than the effective surface area in said intake port portion so that upon movement of said spool from a disposition closing both passages in a direction to open said drive passage the pressurized hydraulic fluid passing therethrough will act on said piston to move said operating rod into passage closing relation to said spool and upon movement of said spool in the opposite direction said return passage will be opened allowing fluid to pass from said opposite portion of said piston chamber to said return chamber and thereby allowing the pressurized fluid in said intake port portion to move said operating rod in the opposite direction into passage closing relation to said spool, and means for selectively positioning said spool to open one or the other of said passages and thereby cause responsive movement of said operating rod by unbalanced application of pressurized hydraulic fluid to said piston with a corresponding movement of said needle bar.
- 15. An electrical control system for generating sequential control signals for commanding the stepwise positioning of an object comprising means for generating a series of electrical signals providing differing magnitude indications proportional to stepwise positions of said object, means selecting a signal from said series, means comparing the magnitude indicated by said selected signal with the magnitude of a pre-existing signal whose magnitude is proportional to the pre-existing position of said object to determine the difference between said magnitudes, means comparing said magnitude difference with a preset maximum magnitude difference, means utilizing the lesser of said differences to select, respectively, either the selected signal or the pre-existing signal combined with the preset maximum magnitude difference, to produce a resulatant control signal, means responsive to said resultant control signal to position an object in proportion to the magnitude of said resultant control signal as limited, means responsive to the magnitude indicated by said selected signal being different from the magnitude of said resultant control signal to interrupt said signal selecting means and thereby maintain said selected signal for processing in said control system as the next selected signal.
- 31. An electrical control system for generating sequential control signals comprising means for generating a series of electrical signals of varying magnitude and including means for scanning said signals, means for selecting a signal from said scanned signals including means for receiving signals from said signal scanning means and for releasing scanned signals, means for periodically cycling said control system to actuate release of a scanned signal by said signal receiving and releasing means, means responsive to said released scanned signal to produce a resultant control signal, the period of cycling actuation of said signal receiving and releasing means by said cycling means being sufficiently imprecise in relation to the frequency of scanning to vary over a range greater than a plurality of periods of the scanning frequency whereby the scanned signal at said signal receiving and releasing means at the instant of actuation to release a signal is an unpredictably randomly selected signal.
Specification