US3633198A

US3633198A - Loom operation indicator circuit

Info

Publication number: US3633198A
Application number: US724389A
Authority: US
Inventors: Lewis E Cassaday
Original assignee: Greenwood Mills Inc
Current assignee: Greenwood Mills Inc; GREENWOOD MILLS
Priority date: 1968-04-26
Filing date: 1968-04-26
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

The invention relates to apparatus for detecting motion of a moving part of a textile machine with a two terminal switch mounted on the moving part which alternately opens and closes when the part is in motion. In one circuit, two capacitors transiently charge when the switch is open and both discharge when the switch is closed. One of the capacitors automatically discharges after charging unless the switch is opening and closing so that this capacitor has a charge only when the part is moving. A transistor may be connected to this capacitor so that the transistor is conductive only when the capacitor has a charge and the part moving.

Description

United States Patent lnventor Lewis E. Cassaday Greenwood, S.C.

Appl. No. 724,389

Filed Apr. 26, 1968 Patented Jan. 4, 1972 Assignee Greenwood Mills Greenwood, S.C.

LOOM OPERATION INDICATOR CIRCUIT 3,284,788 1 H1966 Hudson 340/271 X 3,373,773 3/1968 Balentine 139/336 X 3,516,321 6/1970 Harris 307/293 X4 Primary Examiner-Donald J. Yusko Assistant Examiner-Michael Slobasky Attorney-Cushman, Darby & Cushman ABSTRACT: The invention relates to apparatus for detecting motion of a moving part of a textile machine with a two terminal switch mounted on the moving part which alternately opens and closes when the part is in motion. In one circuit, two capacitors transiently charge when the switch is open and both discharge when the switch is closed. One of the capacitors automatically discharges after charging unless the switch is opening and closing so that this capacitor has a charge only when the part is moving. A transistor may be connected to this capacitor so that the transistor is conductive only when the capacitor has a charge and the part moving.

PATENTED J: 41972 SHEET 1 [IF 2 PATENTEUJAM 4m 3,633,198

SHEET 2 OF 2 All;

IN V ENTOR.

LOOM OPERATION INDICATOR CIRCUIT This invention generally relates to data acquisition equipment and especially to apparatus for determining whether a textile machine is operating or not, and to the combination of such apparatus with a textile machine, such as a loom. In particular, the apparatus determines whether a textile machine part, which normally moves during operation, is in motion, thereby detennining whether the textile machine itself is operating.

In a mill with a number of textile machines it is important to know which machines are in operation and which machines are not. These machines may be looms, spinning frames, knitting machines, or indeed any type of textile machine. This knowledge enables the mill management to make intelligent decisions relating to the material required for each machine and the type and quantity of finished products, such as cloth, which are being produced. In addition, since the pay of the workers operating these machines is often related to the time during which the machine is operating, this knowledge is important in determining payroll schedules and amounts.

Pick counters mounted on each machine have been used in the past to record the number of loom-running cycles. However, such devices provide an output which must be periodically and manually read andwhich cannot be used to supply an immediate indication of the number of machines operating or a permanent record thereof.

Also, in the prior, art both optical and electrical means have been utilized in an attempt to determine when the machine is in operation. Most of the optical systems involve a beam of light which is interrupted only while the machine is operating, while the electrical systems have involved a switch such as a microswitch which remains closed during the whole operation of the machine and is open during nonoperating times, or vice versa, as in the Long et. al. US. Pat. No. 3,340,537. However, both of these methods have been subject to failure in that they can be easily circumvented by shorting the switch contacts or blocking the optical beam with any solid object. This deception may be serious and prevalent if pay is dependent upon the operating time of the machine.

In the invention disclosed in the Dunlap patent application Ser. No. 724,435, filed concurrently herewith as well as in the present invention, such deception cannot be readily practiced because a continually changing or varying electrical signal is necessary to obtain an indication of machine operation. For producing such a signal switch means is mounted on a machine part which normally moves during machine operation, producing a first signal which changes with time while the part is moving, and a secondbut steady signal, for example, a zero signal, while the part is not moving.

However in the circuit disclosed in the aforementioned application Ser. No. 742,435, a three terminal DPST or SPDT switch is mounted on the machine necessitating three wires attached to the switch. In contrast the present invention utilizes a two terminal switch in a different circuit to perform the same function. This less complex switch is not only less expensive and more reliable than a three terminal DPST or SPDT switch but it requires only two wiresconnected to it. This results in a considerable savings in wire since typically only the switch is mounted on a textile machine and the remainder of the detection circuit is quite remote.

The above-mentioned changing and steady signals produced by both the arrangement described herein and in the aforementioned application may then be detected or changed in any suitable manner. However, in this invention, the signals are produced by the two terminal switch and are applied by a two wire cable to an improved RC electrical circuit which produced a bilevel output signal having one level in response to the changing first signal indicating machine operation and a second level in response to the steady second signal indicatingnonoperation.

Both the present invention and the invention described in the aforementioned patent application are especially useful in the textile industry since both can be easily adapted to any textile machine which has a part that moves during operation. Since almost all textile machines have such a part, the invention can be used with a wide variety of textile machines. Furthermore, only the switch means needs to be mounted on the textile machine and the remainder of the circuitry can be located wherever convenient.

The remainder of the circuitry for a number of machines a can then be grouped in a convenient location where the bilevel output voltages of each of the electrical circuits can be read. The circuits can be read sequentially, i.e. one at a time, and the information conveyed to a recorder, computer or other mechanism in a sequential ordered form. This represents a considerable savings in equipment since only one detecting circuit per group is required andonly one input line to the computer or other machinery per group.

In addition, an electrical signal, and, in the embodiment discussed below, a bilevel signal is produced which is especially suitable for input into electronic digital processing equipment, so that a computer can determine at all times which machines are operating and act accordingly. The computer can provide quick replies to inquiries as'well as to control the machines and even route raw materials if desired.

Furthermore, the movingpart of the textile machine is not required to move (oscillate, reciprocate, or rotate, for example) with any particular regularity or at a stable frequency. Detection over a range of speeds and considerable deviation from periodicity is possible. The invention can be operated with virtually any textile machine at virtually'anyspeed simply by changing the value of the circuit components.

Since only the switch itself is a mounted on the textile machine, the system cannot be fooled by shorting the switch or cutting the wires; the part on which the switch is mounted must actually move before operation is detected.

Other objects and advantages will become apparent from reading the detailed description of the invention set forth below in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE'DRAWINGS FIG. 1 shows a loom in front elevation with a switch mounted upon its rocker shaft and leading to an electrical circult to indicate motion and hence operation of the textile machine in accordance with the present invention;

FIG. 2 shows a sectional view of FIG. 1 taken along the lines 2-2 without background, illustrating one type 1 of switch mounted upon the rocker shaft of the textile machine;

FIG. 3 schematically illustrates an electrical'circuit in accordance with one embodiment of the invention; and

FIGS. 4 and 4a illustrate exemplary voltages across the capacitors in FIG. 3 plotted against time.

DETAILED DESCRIPTION OF THE DRAWINGS In the loom shown in FIG. 1 a shuttle 20 is depicted moving between two shuttle boxes 22' and-'24 carrying a pick 25 through the warp threads 26'; The loom depicted is not in= tended to by any particular type of'loom butis merelyintended to be representative of looms and textile machines in general. As is conventionalyrockershaft '30 oscillates'back" and forth about its axis thereby oscillating lay sword's*32-"an d"" 34'which cause the reed-35 to pack the wovencloth'after each trip by the shuttle so that the cloth will be tightly woven. Hence, the rocker shaft provides a convenient and preferred location for a mounting device 36 (see FIG. 2 also) which contains the switch 38 which is used in the FIG. 3 circuit as described below to detect motion of the rocker shaft 30 and hence operation of the textile machine. It will of course be understood that any textile machine part that moves continually only while the machine is in operation can be easily used instead of the rocker shaft, for example a part that oscillates or reciprocates (or even rotates if the switch has a slip ring output or the like) such as a

lay sword

32 or 34 or the arm that drives the take up reel (not shown).

Switch 38 may be a two terminal (SPST) switch of the mercury type as shown in the embodiment in FIG. 3 or indeed any type of appropriate switch including a reed or disturb switch which has two terminals and can alternately open and close. This switch 38 is mounted on the rocker shaft 30 so that the oscillating motion of the rocker shaft 30 causes the switch to oscillate between first and second electrical states and to have a first condition when the shaft 30 is moving and a second condition when it is not, as described in detail below so that motion or lack of motion of the rocker shaft 30 and hence the state of operation or nonoperation of the machine is sensed.

The switch 38 is electrically connected by a cable 40 to the electrical circuitry in block 42 which is preferably located at a remote distance in a locked cabinet in another room, and which may be the type illustrated in FIG. 3. Cable 40, which may be secured by straps 44 to rocker shaft 30 and then pass under or on the floor to the remote location of circuitry 42, is a two wire cable each wire being connected to a terminal of the switch 38. From electrical circuitry 42 to a signal may be obtained by computer 46, indicating whether rocker shaft 30 is oscillating and hence whether the loom is operating.

Computer 46 also receives signals from all other looms in the mill similarly equipped and correlates these signals to provide whatever information is desired. It may be convenient to group some of the electrical circuits 42 together. The mill would then be divided into a number of such groups. In each group each circuit 42 can then be sensed sequentially and the information passed on to the computer 46. Each circuit 42 can then be checked every minute or at whatever interval desired to determine whether the machine associated with it is operatmg.

Other systems have utilized graphical and other recorders to provide a permanent and accurate record of machine operation. For example in the patent to Long et al., US. Pat. No. 3,340,537 counters and recorders, including a drum recorder, are used to record operating and nonoperating times of a textile machine. This invention also can be used with records, counters or other equipment and is not limited to use with computers.

A digital computer, however, can act upon the information received as well as record it. The computer can response quickly to inquiries about any given machine, and provide all necessary data nearly instantaneously. In addition, all data on all machines can be produced regularly in convenient printed form. The computer can further provide punched cards for payroll schedules or simply prepare the payroll on the basis of its own information. The computer can in addition control the output of each of the different products being made and properly route raw materials.

Switch 38 may be mounted on the rocker shaft 30 by any means which keeps the switch firmly in place while the rocker shaft 30 oscillates. FIG. 2 shows one way by which the switch 38 may be secured to the rocker arm 30. An inverted U- shaped bolt 48 fits around the rocker arm 30 and a block 50 is secured below the rocker arm 30 by passing the bolt 48 through two holes in the block 50 and applying nuts 52 and 54 to the threadedends of the bolt 48. The switch 38 may be attached to the block 50 or sealing fastened within it as shown. Fastening the switch 38 inside the block 50 provides an additional measure of safety against tampering. AS conventional for mercury switches, it includes a housing containing a mercury ball 56, and contains a pair of contacts or terminals at one end for connection as shown in FIG. 3. When rocker shaft 30 is oscillating, the ball of mercury 56 moves from one end of the switch 38 to the other so that the contacts therein are alternately electrically connected and disconnected.

In FIG. 3, a circuit is disclosed which is capable of sensing the motion of a moving part in a typical textile machine, for example, the oscillating motion of the rocker shaft 30 of the textile machine shown in FIG. 1. Switch 38, which is a two terminal (SPST) switch having a first electrical state when its switch arm 98 is open and a second state when that arm is closed, is mounted in the same way as described in connection with FIG. 2, and automatically and alternately opens and closes if the rocker shaft 30 is oscillating and hence the loom is operating. The

capacitors

100 and 102 then are alternately charged and discharged provided that the switch is opening and closing. The presence of voltage across the capacitor 102, which, as explained below, occurs only when the switch arm 98 is alternately opening and closing, maintains a positive potential between the base and an emitter of the NPN- transistor 104, thereby keeping transistor 104 in a state of conduction which can be sensed and which thereby indicates the motion of the rocker shaft 30 and hence operating of the loom.

The operation of the circuit of FIG. 3 is now discussed in detail. If the direct circuit source 106 is applied or activated when the switch 38 is in a closed position, current will simply flow through the resistor 108 and the switch 38 without disturbing any of the other components of the circuit. A direct current voltage of about l0 volts has been satisfactory for source 106, which though shown as a battery may be rectified AC, preferably well regulated or filtered. The source 106 may also supply the power requirements of a number of systems similar to the system described herein associated with a number of different machines. It may be desirable to mount the switch 38 so that, when the machine is not operating, the switch is open and current will not flow in the steady state condition through resistor 108. However, if switch 38 is in or moves to an open position after the source 106 is activated, current flows through resistor 108, capacitor 100, diode 112 and the parallel combination of capacitor 102 and resistor l 14. Since the NPN-transistor 104 will be in a state of nonconduction, no current can immediately flow through the resistor 116. A PNP-transistor can be substituted for transistor 104 merely by reversing the polarity of the source 106 and the direction of the

diodes

112 and 126.

In the graph of FIG. 4, when switch 38 opens as the time t the voltage across capacitor 100, which is labeled V begins to rise exponentially and so does the voltage V across the capacitor 102 as shown in FIG. 4a. After the voltage between the base and emitter of transistor 104 is great enough to drive the transistor into conduction, the rate of charging will decrease since the resistor 116 is effectively connected in parallel with resistor 114. The resistor 116 also limits the flow of current through transistor 104 to a value below that which might damage the transistor 104. If switch 38 remains open, the capacitor 100 will continue to charge as shown by dash line 120 until the voltage V is essentially equal to the voltage across the direct current source 106.

As above indicated, the same time that capacitor 100 is charging between time t and t, capacitor 102 is also exhibiting a net and transient increase in charge as shown in FIG. 4a. This is mathematically the sum of a positive function having an exponential decay and a negative function having an exponential decay, each of which has the same initial value but a different time constant. If the switch 38 remains in a an open positive as it would if the loom were not operating then, the voltage V will peak and then decay along dashed line 123 toward a steady state value of zero volts as the two exponential functions, the sum of which makes up V each decay toward a steady state value of zero volts.

However, if the rocker shaft or other moving part is oscillating, switch 38 will close before the voltage across capacitor 100 charges to the voltage of the source 106 or the voltage across capacitor 102 decays to zero. It may be desirable to choose the capacitor and resistor values so that switching will occur approximately at a time when voltage V is maximum.

For the purpose of discussion, it is assumed that switch 38 closes at a time which is noted by t, in the graphs of FIG. 4, and which is near the maximum voltage which can appear across capacitor 102. It will, of course, be understood that the component values of the

resistors

108, 114 and 116 and the

capacitors

100 and 102 can be chosen so that the times at which opening or closing occur will be at another location during the charging or discharging of the

capacitors

100 and 102 and that switching may occur at times other than t t t etc. Furthermore, time intervals between t and t, and etc. need not be uniform or even approximately the same.

The closing of switch 38 connects capacitor 100 across the serial combination of resistor 124 and diode 126. When switch 38 is open, the diode 126 prevents the passage of current through itself and hence through resistor 124, since point 128 is at a higher potential than point 130. However, the closing of switch 38 connects point 132, which is at a higher potential than point 128, to point 130 so that current flows through resistor 124 and diode 126, and capacitor 100 discharges through resistor 124. This discharge of capacitor 100 is shown in FIG. 4 by the exponential voltage V decay between the time t when switch 38 closes and time t when it reopens. If switch 38 remains closed V will decay toward zero along the dash line 134. It will, of course, be understood that the rate of discharge of capacitor 100 can be easily controlled by changing the value of resistor 124 and hence the rate of discharge. It may he desirably to discharge the capacitor 100 quickly as shown in FIG. 4 and hence a value of resistor 124 would be chosen which would be appropriate to accomplish this.

The closing of switch 38 also isolates capacitor 102 from capacitor 100 since diode 112 now prevents the passage of current between

points

128 and 136 so that capacitor 102 also discharges exponentially, as shown in FIG. 4a between times t, and t This discharge is primarily through resistor 114 although some current may flow through resistor 116 and transistor 104 until transistor 104 becomes nonconductive. If the loom stops operating while switch 38 remains closed, the voltage across capacitor 102, decays to zero as shown along the dashed line 138 in FIG. 4a, with the result that the base emitter voltage of transistor 104 is reduced below the value necessary to maintain the transistor 104 in a state of conduction.

If, however, switch 38 reopens at a time t the voltage across capacitor 102 will againbuild up in the same manner as when switch 38 was initially opened. Similarly, voltage across capacitor 100 will rise exponentially in the same manner as when switch 30 was initially opened. The time constant, however, will be slightly decreased since the resistor 116 is effectively in parallel with the resistor 114 because the transistor 104 is in a conductive state. This process of alternate charging and discharging will be repeated as long as switch 38 is periodically opening and closing, so that the detectable state of conduction or nonconduction of transistor 104 will indicate motion or lack of motion of rocker shaft 30, and hence operation or lack of operation of the loom. It will be appreciated that the motion of the rocker shaft 30, or other moving part upon which the switch 38 is mounted, need not be precisely periodic nor operated at the same frequency at all times.

The circuit discussed in FIG. 3 is capable of indicating motion even if the frequency of the rocker shaft should vary to be slightly aperiodic. Looms, which are but one type of textile machine with which the present invention may be used or combined, often operate at a frequency of about 176 cycles per minute but can vary from below 80 cycles per minutes to above 360 cycles per minutes. The circuit is then capable of detecting motion should motion vary from that expected and the value of the circuit components can be easily changed to accommodate any machine which has moving parts operating at nearly any speed.

A simple type of circuit for sensing the conduction or nonconduction of transistor 104 as shown in FIG. 3 includes a switch which connects a source of direct current 142 and a resistor 144 between the collector and emitter of transistor 104. When switch 140 is closed the current through or voltage across resistor 144 may be sensed to determine whether transistor 104 is in a conductive or a nonconductive state-The computer 46 of FIG. 1 may operate similarly as to the electrical circuitry for each loom. For example, it may be convenient to locate the electrical circuitry for a group of looms together and utilize one sensing circuit to sense each of theelectrical circuits from each of the looms sequentially. Each of the groups of electrical circuitry wouldthen-be linked to the computer 50 by one line which carries the signalrepresenting each of the machines, sequentially. This arrangement results in a considerable savings in wiring and electrical components. The checking of the operation of the machine could take place at intervals of one minute or any other convenient interval.

Summarizing, both of the capacitors in FIG. 3 charge when the switch 38 is open and both discharge when it is closed, each through its own resistor which is isolated from the other capacitor. The second capacitor recharges only transiently and will decay to a potential of zero volts in steady state, i.e., when switch 38 stops in either an open or closed condition. However, the constant opening and closing of switch 38 prevents the second capacitor 102 from reaching such a steady state, by keeping a net charge on it. A transistor 104 is connected across the second capacitor so when capacitor 102 has a net charge as effected by oscillation of switch 38, the voltage between the base and emitter is sufficient to keep transistor 104 in a detectable state of conduction. When switch 38 stops moving with its arm 98 either closedor open, the charge on condenser 102 decays and the base emitter voltage reduces to effect cut off of transistor 104, providing a detectable state of nonconduction.

Many changes and modification of the above structure and circuitry is possible without departing from .the spirit'of the invention. Although mercury tilt switches have beendiscussed particularly, many other twoterminal switches such as reed or disturb switches may also be used. In addition the output transistor may be either a NPN- or PNP-type depending in the polarity of the direct current source and, in-the circuit of FIG. 3, the direction of the diodes. The transistor merely operates as an ON-OFF bilevel output device and can be easily replaced with any other type of appropriate solid-state device or other switch device, such as a relay. The switchcan also be located on any appropriate moving part of the textile machine and is not intended to the limited to the rocker shaft. Further, the invention contemplates a motion detection system to be used with a textile machine as well as in combination with a textile machine. Accordingly, the scope of the invention is intended to be limited only by the scope of the appended claims.

What is claimed is:

1. Apparatus for detecting operation of a textile machine which has a part that moves in a given manner only during operation of said machine comprising:

a two terminal switch adapted to be mounted on said moving part of said machine, said switch alternately-opening and closing only when said part is moving, and not alternately opening and closing when said part is not moving, and

electric circuit means adapted for connection to a source of direct current voltage, including two wires only connected to said switch, for exhibiting a first output voltage only when said switch is alternately opening and closing due to the movement of said part as aforesaid indicating operation of said machine and for exhibiting a secondoutput voltage when said switch-is not alternately opening and closing and is either open or closed indicating nonoperation of said machine, including afirst capacitor and a first resistor connected in parallel, so that said first capacitor retains a net charge only when said switchisalternately opening and closingand a second capacitor, and

a second resistor, so that said first capacitor is transiently charged by said source through said second capacitor when said switch is open and said second capacitor is discharged through said second resistor when said switch is closed.

2. A textile machine in combination with the apparatus of claim 1 and comprising a loom having as said moving part a rocker shaft on which said switch is mounted for oscillation therewith.

3. Apparatus as in claim 1 wherein said circuit means includes a source of direct current voltage.

4. Apparatus as in claim 3 wherein said circuit means includes a transistor having said first capacitor connected between its base and emitter for providing an output indicating whether said part is moving.

5. Apparatus as in claim 4 wherein said circuit means includes a diode connected between said capacitors so that current can flow from said second capacitor to said first capacitor only when said first capacitor is charging.

6. Apparatus for detecting motion of a moving part of a textile machine comprising:

a source of direct current voltage,

a first capacitor connected to said source,

a second capacitor and a resistor connected in parallel with each other and connected to said first capacitor, and

a two terminal switch connected to said first capacitor and adapted to be mounted on said part so that said switch alternately opens and closes when said part is in motion, allowing said source to change said capacitors when said switch is opened and to discharge said capacitors when said switch is closed, said second capacitor being charged transiently when said switch is open so that said second capacitor retains a net charge only when said switch alternately opens and closes.

7. Apparatus for detecting motion of a moving part in a textile machine comprising:

a switch adapted to be mounted on said part, said switch alternately opening and closing when said part is in motion,

a first resistor,

a source of direct current voltage applied across said switch via said first resistor,

a first capacitor having one side attached to one said of said switch,

a serially connected second resistor and first diode attached to the other side of said first capacitor, said first diode being positioned to prevent passage of current through said second resistor when said switch is open,

a second diode having one end attached to said other side of said capacitor, said diode being adapted to prevent the passage of current through said second diode when said switch is closed,

a parallel connected second resistor and second capacitor connected between the other end of said diode and other side of said switch, and

a transistor having its base connected to the said other end of said diode and its emitter to the said other end of said switch so that said transistor is conductive when said second capacitor is charged.

Claims

1. Apparatus for detecting operation of a textile machine which has a part that moves in a given manner only during operation of said machine comprising: a two terminal switch adapted to be mounted on said moving part of said machine, said switch alternately opening and closing only when said part is moving, and not alternately opening and closing when said part is not moving, and electric circuit means adapted for connection to a source of direct current voltage, including two wires only connected to said switch, for exhibiting a first output voltage only when said switch is alternately opening and closing due to the movement of said part as aforesaid indicating operation of said machine and for exhibiting a second output voltage when said switch is not alternately opening and closing and is either open or closed indicating nonoperation of said machine, including a first capacitor and a first resistor connected in parallel, so that said first capacitor retains a net charge only when said switch is alternately opening and closing and a second capacitor, and a second resistor, so that said first capacitor is transiently charged by said source through said second capacitor when said switch is open and said second capacitor is discharged through said second resistor when said switch is closed.

6. Apparatus for detecting motion of a moving part of a textile machine comprising: a source of direct current voltage, a first capacitor connected to Said source, a second capacitor and a resistor connected in parallel with each other and connected to said first capacitor, and a two terminal switch connected to said first capacitor and adapted to be mounted on said part so that said switch alternately opens and closes when said part is in motion, allowing said source to change said capacitors when said switch is opened and to discharge said capacitors when said switch is closed, said second capacitor being charged transiently when said switch is open so that said second capacitor retains a net charge only when said switch alternately opens and closes.

7. Apparatus for detecting motion of a moving part in a textile machine comprising: a switch adapted to be mounted on said part, said switch alternately opening and closing when said part is in motion, a first resistor, a source of direct current voltage applied across said switch via said first resistor, a first capacitor having one side attached to one said of said switch, a serially connected second resistor and first diode attached to the other side of said first capacitor, said first diode being positioned to prevent passage of current through said second resistor when said switch is open, a second diode having one end attached to said other side of said capacitor, said diode being adapted to prevent the passage of current through said second diode when said switch is closed, a parallel connected second resistor and second capacitor connected between the other end of said diode and other side of said switch, and a transistor having its base connected to the said other end of said diode and its emitter to the said other end of said switch so that said transistor is conductive when said second capacitor is charged.