YARN DETECTOR SWITCH-UPPER
United States Patent 3851502
An upper switch for monitoring the year as it is being drawn from a supply spool to stop the knitting machine and light an indicator lamp under abnormal conditions that it detects such as an undue increase in yarn tension above a predetermined adjustable value, break in the yarn, absence or end of yarn, or a decrease in yarn tension or a large amount of slack in the yarn. In this upper yarn detector switch, parts that wear have been made readily replaceable, the switch lever counterweight has been made adjustable and arranged to decrease the applied weight as the switch lever falls, the switch has been provided with a contact making cam that won't hang up, and improved tripping tension adjusting and indicating means and other improvements have been provided.
US Patent References:
Electric stop mechanism for knitting machines
Vossen - July 1942 - 2290303
/2467952.html
Antonevich - April 1949 - 2467952
Electrical stop motion for knitting machines
Arrowood - April 1949 - 2468611
Stop motion for knitting machines with full range adjustment
Vossen - July 1950 - 2515479
Yarn detecting mechanism for textile machine stop motions
Martin et al. - May 1956 - 2744174
Electric stop mechanism for knitting machines
Vossen - July 1942 - 2290303
/2467952.html
Antonevich - April 1949 - 2467952
Electrical stop motion for knitting machines
Arrowood - April 1949 - 2468611
Stop motion for knitting machines with full range adjustment
Vossen - July 1950 - 2515479
Yarn detecting mechanism for textile machine stop motions
Martin et al. - May 1956 - 2744174
Application Number:
05/337924
Publication Date:
12/03/1974
Filing Date:
03/05/1973
View Patent Images:
Export Citation:
Assignee:
Control Switch, Inc. (Folcroft, PA)
Primary Class:
Other Classes:
200/61.130, 200/61.180
International Classes:
D04B35/12; D04B35/14; D04B35/00; D04B35/14
Field of Search:
66/163,157,161 57/81 28/51 139/370 200/61.13,61.14,61.18 340/259
US Patent References:
Primary Examiner:
Kee Chi, James
Attorney, Agent or Firm:
Rather, Autio Wm H. R. A.
Claims:
I claim
1. A yarn detector device comprising:
2. The invention defined in claim 1, wherein:
3. The invention defined in claim 1, wherein:
4. The invention defined in claim 1, wherein:
5. The invention in claim 1, wherein:
6. The invention defined in claim 1, wherein:
7. The invention defined in claim 6, wherein:
8. The invention defined in claim 1, wherein switch comprises:
9. The invention defined in claim 1, wherein said toggle spring mechanism also comprises:
10. The invention defined in claim 9, wherein said toggle spring mechanism also comprises:
11. The invention defined in claim 1, wherein said circuit comprises:
12. The invention defined in claim 1, wherein said external guide member, trip member and feeler member are provided with configurations which afford ease in replacing the yarn back into operative position following tripping.
1. A yarn detector device comprising:
2. The invention defined in claim 1, wherein:
3. The invention defined in claim 1, wherein:
4. The invention defined in claim 1, wherein:
5. The invention in claim 1, wherein:
6. The invention defined in claim 1, wherein:
7. The invention defined in claim 6, wherein:
8. The invention defined in claim 1, wherein switch comprises:
9. The invention defined in claim 1, wherein said toggle spring mechanism also comprises:
10. The invention defined in claim 9, wherein said toggle spring mechanism also comprises:
11. The invention defined in claim 1, wherein said circuit comprises:
12. The invention defined in claim 1, wherein said external guide member, trip member and feeler member are provided with configurations which afford ease in replacing the yarn back into operative position following tripping.
Description:
BACKGROUND OF THE INVENTION
Yarn detector switches have been known heretofore such as those shown in E. Vossen U.S. Pat. Nos. 2,290,303; 2,515,479 and 3,257,518 and C. S. Martin et al. U.S. Pat. No. 2,744,174.
While these yarn detector switches have been useful for their intended purposes, this invention relates to improvements thereover.
SUMMARY OF THE INVENTION
This invention relates to upper yarn detector switches for use where the yarn leaves the supply spool for the knitting machine for sensing the yarn and stopping the knitting machine when undue tension, slack, absence of yarn or the like is detected.
An object of the invention is to provide an improved upper yarn detector switch.
A more specific object of the invention is to provide a yarn detector switch with improved, readily replaceable wear parts.
Another specific object of the invention is to provide a yarn detector switch affording replacement of electrical contact members and components (bulb and resistor) without special tools or soldering.
Another specific object of the invention is to provide a yarn detector switch with an improved yarn feeler counterweight structure that is adjustable and operable to decrease the applied counterweight as such feeler actuates toward switch closure.
Another specific object of the invention is to provide a yarn detector switch with an improved movable contact that won't hang up under yarn feeler operation.
Another specific object of the invention is to provide a yarn detector switch with improved tripping tension adjusting and indicating means.
Another specific object of the invention is to provide yarn re-positioning means requiring minimum operator technique and skill.
Another specific object of the invention is to provide grounding of all surfaces that come into contact with the yarn during normal operation of the knitting machine.
Other objects and advantages of the invention will hereinafter appear.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged isometric view of an upper yarn detector switch constructed in accordance with the invention;
FIG. 2 is a front elevational view thereof with the front cover removed to show the internal parts;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a vertical cross-sectional view taken along line 4--4 of FIG. 2;
FIG. 5 is a horizontal cross-sectional view taken along line 5--5 of FIG. 2;
FIG. 6 is an isometric view of the stationary contact member shown in FIG. 2;
FIG. 7 is an isometric view of the electrical connector member shown in FIG. 2; and
FIG. 8 is a circuit diagram thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-3, there is shown an upper yarn detector switch according to the invention. This switch has an insulating housing 2 including a removable front cover 4 secured to the housing by three screws 6. A mounting bracket 8 is secured to the housing for snap-in mounting of the switch to a horizontally-running strip or bar, this mounting bracket or clip also serving as one terminal for the electrical circuit therein. The yarn runs below guide bracket 10, above the yarn tension trip lever or snag arm 12, and below the yarn feeler lever or switch arm 14 as shown in FIGS. 2 and 3.
The housing is provided with a mechanism enclosing portion 2a and a yarn supporting portion 2b. The mechanism enclosing portion is generally square-shaped in front view with rounded corners as shown in FIG. 2 providing a compartment of sufficient depth as shown in FIGS. 4 and 5 for housing the operating mechanism. This compartment is closed by front cover 4 as shown in FIGS. 1, 4 and 5. The housing is preferably molded of plastic material so that yarn supporting portion 2b is integral with mechanism enclosing portion 2a thereof. Yarn supporting portion 2b tapers generally toward the right from the right wall of the compartment of portion 2a and is provided with a front-to-back groove 2c on its underside near its tip to provide a passageway for the yarn as shown in FIG. 2.
The compartment in the housing is provided with a number of molded wals and projections hereinafter described for positioning and retaining the elements of the operating mechanism.
The operating mechanism comprises generally the following parts:
1. A toggle (overcenter) spring mechanism for trip lever 12.
2. Adjusting means affording external manual adjustment of the tension of the toggle spring mechanism thereby to select the magnitude of yarn tension at which the switch will trip.
3. A switch operated by the feeler lever.
4. A yarn detector electrical circuit including the switch and a resistor in series.
5. An indicator lamp connected in the yarn detector circuit in series with the switch and in parallel with the resistor.
The toggle spring mechanism is mounted on a bracket plate 16 that lies against the rear wall of the compartment primarily, and has two forwardly bent portions 16a and 16b that lie against the upper wall of the compartment as shown in FIG. 5, and has a downwardly bent portion 16c that lies against the front cover as shown in FIG. 4, this portion 16c being bent down from forward portion 16b to form a pivot for the toggle spring mechanism. This bracket plate is secured to the housing by a pair of rivets including a pivot 18 that is inserted through a hole in the rear wall of the housing and a hole in the bracket plate and is staked within the compartment as shown in FIG. 4 to secure it in place. The other rivet 20 shown in FIGS. 2 and 5 goes through portion 16a of the bracket plate and the upper wall of the housing and serves also to secure combined mounting clip and terminal 8 to the housing as well as securing the bracket plate within the housing compartment.
The bracket plate is provided with a pair of aligned notches for pivoting crank shaft 22. For this purpose, a front notch 16d is provided in portion 16c as shown in FIG. 2 and a like rear notch is provided directly behind it in the main body of the bracket plate that lies against the rear wall of the compartment. These two notches are spaced from one another by the depth of the compartment as shown in FIG. 5 and afford space therebetween for the central swinging portion of crank shaft 22. The opposite ends of the crank shaft extend through holes in the rear wall and front cover and through respective bushings 2d and 4a thereon as shown in FIG. 5. The extreme ends of this crank shaft are flattened to fit into slits in the ends of trip lever 12 to afford turning of the crank shaft by the trip lever in response to undue yarn tension.
A tension spring 24 of the helical type provides the toggle action. The center of the swinging part of crank shaft 22 is provided with a re-entrant bend to form a notch for retaining one end hook of spring 24 as shown in FIG. 5. A fixed but adjustable slide member 26 is provided with a hole as shown in FIG. 4 for retaining the other hook of this spring so that the spring is stressed in tension therebetween.
The aforementioned tension adjusting means comprises slide member 26 and a worm 28 that meshes with a rack 26a on the lower surface of slide member 26. As shown in FIG. 2, the left end portion of slide member 26 is slidably held in a groove between an upper wall 2e and a lower wall 2f integrally molded in the housing. Wall 2e has a forwardly projecting portion 2g at its right end as shown in FIGS. 2 and 5 to form a rest for portion 16c of the bracket plate to retain the latter securely in its place, the remainder of this wall being slightly narrower to provide clearance for the upper end of pointer 30. Worm 28 is tapered to remain in mesh with the slightly angularly-disposed rack 26a. This worm is integral with a horizontal shaft 28a that terminates in an external knob 28b having a hexagonal shape for manual turning. This worm is held in place by a pair of walls 2h and 2j forming a groove therebetween molded in the housing through which groove the worm shaft passes, these walls bearing against the worm and the left wall of the compartment bearing against the knob to hold the worm fixed within the housing. In addition, bracket plate 16 is provided with a forwardly-projecting finger 16e having a tab 16f bent over the tip of the shaft beyond the worm to keep the worm from rising out of its slot in the housing as shown in FIGS. 2 and 4. Another projection 2k integrally molded in the housing is located below this tip of the worm shaft to hold the worm up against and in mesh with the rack. The part of the shaft 28a immediately adjacent the knob also passes through a groove in the left wall of the compartment to hold it fixed but rotatable.
Slide member 26 is provided with a notch in its front edge for retaining the circular upper end of pointer 30 and for rotating this pointer as the slide member is moved by turning the knob. This pointer is pivoted at its intermediate portion on a short round projection 2m integrally molded on wall 2h. A curved wall 2n is molded in the housing directly below the tip of the pointer to make this pointer visible through the transparent cover by providing a light colored background for the black pointer.
The aforementioned yarn detector circuit extends as shown in FIGS. 2 and 8 from mounting clip 8 through its rivet 20, bracket plate 16 and pivot 18 to movable cam contact 32. This circuit then continues from stationary spring contact 34 (shown also in FIG. 6), resistor 36 and connector 38 (also shown in FIG. 7) and the rivet through the rear wall to external connector 40. Lamp bulb 42 is connected between stationary contact 34 and connector 38 in parallel with resistor 36.
As shown in FIG. 4, pivot 18 serves a number of purposes. As hereinbefore described, it serves as a rivet to secure bracket plate 16 to the housing. It also serves as a pivot for the rear arm of feeler lever 14. For this purpose, it is provided with a round bore shown in FIG. 4 extending partway in from its outer end in which the forwardly-bent end of the rear arm of the feeler lever is pivoted and in which the feeler lever is held by its own spring bias. Pivot 18 also serves to pivotally support movable cam contact 32. For this purpose, pivot 18 is provided with a reduced diameter forward end portion that extends into the center hole of the movable contact to freely support the latter for rotation thereon.
Movable contact 32 is thus freely pivoted for engaging stationary spring contact 34. As shown in FIG. 2, movable contact 32 is bowknot shaped having cam segments on opposite sides 180° apart so that either cam can be positioned in assembly for engagement with the stationary contact. The center hole therein is provided with a pair of slots extending toward the cams, respectively, to receive the contact driver finger in either slot when the switch is assembled.
The movable contact driver shaft 44 is shown in FIGS. 1 and 4. It comprises an insulating shaft having an enlarged slotted external head. The shaft extends through a hole and an integral internal bushing 4b in cover 4 and is rotatably secured therein by a C-washer 45 snapped into a groove in the shaft at the inner end of bushing 4b. The inner end of this driver shaft has a driver finger 44a, eccentrically offset from its center, and a leveling surface at its other side with a recess therebetween for accommodating the reduced end of pivot 18. This driver finger enters one of the slots in movable contact 32 and the leveling surface holds the movable contact concentrically on pivot 18 so that when feeler lever 14 pivots counterclockwise, the movable contact will freely rotate to be cammed into sliding engagement with contact spring 34 to close the switch.
The slot 44b in the external head of driver shaft 44 is shaped to retain the front arm of the feeler lever. As shown in FIG. 1, this slot is provided with a central constriction and the end portion of the front arm of feeler lever 14 is provided with a pair of spaced flattened, wider sections entering on opposite sides of this constriction whereby the feeler lever is snapped in and held in place by its own spring bias.
The external head of driver shaft 44 is provided with means for mounting an adjustable counterweight 46. This means comprises a tapped eccentric projection 44c extending from one edge of the head at substantially a 90° angle counterclockwise from and relative to driver finger 44a so that when the driver finger is at the top, the counterweight will extend substantially horizontally to the left. This counterweight is a metal stud treaded at one end to a substantial length for adjustment into or out of eccentric projection 44c of the driver, this adjustment being made by turning the counterweight at screwdriver slot 46a at its other end.
Following along the yarn detector circuit in the direction it was traced above, the next element is stationary contact 34. As shown in FIGS. 1 and 4, the narrow upstanding portion thereof extends down alongside the movable contact where it can be engaged and then takes a 90° turn left where it enlarges to a wider left-hand section as shown in FIG. 6. This wider section has a notch 34a at its rear edge fitting over a complementary lug in the housing below wall 2n to securely retain it in place. Additionally, this left-hand section of contact 34 is held slightly bowed between the lower surface of wall 2n and spaced wall and stud 2p and 2q molded within the base as shown in FIG. 2. Stud 2q has a hole for receiving one rearwardly-bent wire of resistor 36 for mechanically mounting the latter, and contact 34 has a downwardly-angled connector spring finger 34b shown in FIG. 6 pressing on this resistor wire to make an electrical connection to the resistor as shown in FIG. 2. To provide clearance for connection finger 34b, stud 2q is slightly shorter than wall 2p.
The other wire of resistor 36 is connected by connector 38 to external terminal 40. For this purpose, connector 38 has the configuration shown in FIG. 7. It is riveted at its upper end through the rear wall to terminal 40 as hereinbefore described. It extends down along the right wall of the compartment and through the narrow slot between cover-mounting stud 2r and the lower-right corner wall of the housing and then along the bottom wall of the housing terminating in a notch in wall 2p as shown in FIG. 2. A notch 38a is provided in the rear edge of this connector as shown in FIG. 7 to fit over a complementary lug at the root of stud 2q to retain the connector in secure position in the housing. The part of this connector strip directly above corner stud 2r is provided with a clamp for clamping the other wire of resistor 36. For this purpose, the connector strip is provided with a leftward re-entrant bend 38b and a spring finger 38c is sheared from the forward edge and bent at an angle past this bend. This spring finger is then pressed clear of the bend and the resistor wire inserted within the bend and the finger allowed to spring back against the wire to bias it within the bend to make a pressure electrical connection.
The left end of connector 38 is provided with a lamp socket 38d. For this purpose, the connector strip is provided with a round hole having a short slot at its edge as shown in FIG. 7. The edge of this hole is then formed with a gradual angle with one side of this slot formed up and the other side formed down to fit the threads of the lamp bulb. When the lamp bulb is screwed in this socket, the center terminal thereof is pressed against downwardly angled tongue 34c of contact 34 as shown in FIGS. 2 and 6 to connect the trip indicator lamp across resistor 36.
Cover 4 is provided with a pair of lugs 4b and 4c fitting into corresponding notches above lamp 42 and shaft 28a, respectively. Cover 4 is also provided with an integrally molded forwardly extending stud 4d to hold driver shaft 44 from rotating to facilitate assembly of the cover and insertion of driver finger 44a into the slot in the movable contact cam. Cover 4 is further provided with a transparent window 4e through which pointer 30 shows and a scale of numbers along this window to indicate the tension adjustment when the knob is turned.
The housing is provided with an integrally molded forwardly extending stud 2s forming a stop for feeler lever 14. This stop allows movable contact 32 to engage stationary spring contact 34 and to deflect the latter a limited amount for good contact.
As will be apparent from FIGS. 1 and 2, yarn tension trip lever 12 may be moved down or clockwise a small amount whereupon crank shaft 22 passes the line of action of spring 24 to snap lever 12 all the way. Lever 12 stops when crank shaft 22 abuts the upper wall of the housing. The yarn may then be placed across the bend of lever 12 and this lever moved up or counterclockwise until it snaps over-center into the position shown in FIG. 2. In thus moving up, the yarn carries feeler lever 14 along with it so that the feeler lever rests on the yarn. Thus, the yarn will pass between the upward re-entrant bend in bracket 10 and the downward re-entrant bend in trip lever 12 and below feeler lever 14.
In the case of a snag in the yarn or undue tension or the like, the yarn will pull trip arm 12 down until it will snap over-center. This allows feeler arm 14 to fall clockwise to close the switch to stop the knitting machine and light the indicator lamp.
In case of undue slack in the yarn, or breakage, or end of yarn, feeler arm 14 falls and closes the switch with the same result as above.
As will be apparent, the parts that wear are readily replaceable. Bracket 10 is inserted at its left end in a notch 2t in the bottom of the housing adjacent the indicator lamp and its right ends are bent toward one another and snap into holes 2u in the right end yarn supporting portion 2b of the housing. When this bracket wears by rubbing of the yarn thereon, its ends can be spread apart clear of holes 2u and the bracket removed and readily replaced with a new one.
Feeler arm 14 is also readily replaceable should it wear by rubbing of the yarn. Its rear arms can be spread apart so that the forwardly-bent end on its rear arm clears the hole in pivot 18 (FIG. 4) and its front arm clears the slot in the head of driver shaft 44 (FIG. 1). A new feeler lever can readily be assembled in its place.
Similarly, trip lever 12 is readily replaceable should it wear by the yarn running thereover. Its two arms can be spread apart clear of the ends of crank shaft 22 and the lever removed and replaced with a new one.
As will be apparent from FIG. 1, counterweight 46 is readily adjustable by inserting a screwdriver into slot 46a and turning the counterweight in or out. Its effective weight varies with the length of its horizontal lever arm from the axis of the driver shaft. Its applied counterweight decreases as the feeler lever falls to enhance closing of the switch. As this feeler lever falls, its counterweight is carried clockwise above the axis of the driver shaft so that the horizontal projection of its lever arm decreases in length thereby to decrease the counterweight.
While the apparatus hereinbefore described is effectively adapted to fulfill the objects stated, it is to be understood that the invention is not intended to be confined to the particular preferred embodiment of upper yarn detector switch disclosed, inasmuch as it is susceptible of various modifications without departing from the scope of the appended claims.
Yarn detector switches have been known heretofore such as those shown in E. Vossen U.S. Pat. Nos. 2,290,303; 2,515,479 and 3,257,518 and C. S. Martin et al. U.S. Pat. No. 2,744,174.
While these yarn detector switches have been useful for their intended purposes, this invention relates to improvements thereover.
SUMMARY OF THE INVENTION
This invention relates to upper yarn detector switches for use where the yarn leaves the supply spool for the knitting machine for sensing the yarn and stopping the knitting machine when undue tension, slack, absence of yarn or the like is detected.
An object of the invention is to provide an improved upper yarn detector switch.
A more specific object of the invention is to provide a yarn detector switch with improved, readily replaceable wear parts.
Another specific object of the invention is to provide a yarn detector switch affording replacement of electrical contact members and components (bulb and resistor) without special tools or soldering.
Another specific object of the invention is to provide a yarn detector switch with an improved yarn feeler counterweight structure that is adjustable and operable to decrease the applied counterweight as such feeler actuates toward switch closure.
Another specific object of the invention is to provide a yarn detector switch with an improved movable contact that won't hang up under yarn feeler operation.
Another specific object of the invention is to provide a yarn detector switch with improved tripping tension adjusting and indicating means.
Another specific object of the invention is to provide yarn re-positioning means requiring minimum operator technique and skill.
Another specific object of the invention is to provide grounding of all surfaces that come into contact with the yarn during normal operation of the knitting machine.
Other objects and advantages of the invention will hereinafter appear.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged isometric view of an upper yarn detector switch constructed in accordance with the invention;
FIG. 2 is a front elevational view thereof with the front cover removed to show the internal parts;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a vertical cross-sectional view taken along line 4--4 of FIG. 2;
FIG. 5 is a horizontal cross-sectional view taken along line 5--5 of FIG. 2;
FIG. 6 is an isometric view of the stationary contact member shown in FIG. 2;
FIG. 7 is an isometric view of the electrical connector member shown in FIG. 2; and
FIG. 8 is a circuit diagram thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-3, there is shown an upper yarn detector switch according to the invention. This switch has an insulating housing 2 including a removable front cover 4 secured to the housing by three screws 6. A mounting bracket 8 is secured to the housing for snap-in mounting of the switch to a horizontally-running strip or bar, this mounting bracket or clip also serving as one terminal for the electrical circuit therein. The yarn runs below guide bracket 10, above the yarn tension trip lever or snag arm 12, and below the yarn feeler lever or switch arm 14 as shown in FIGS. 2 and 3.
The housing is provided with a mechanism enclosing portion 2a and a yarn supporting portion 2b. The mechanism enclosing portion is generally square-shaped in front view with rounded corners as shown in FIG. 2 providing a compartment of sufficient depth as shown in FIGS. 4 and 5 for housing the operating mechanism. This compartment is closed by front cover 4 as shown in FIGS. 1, 4 and 5. The housing is preferably molded of plastic material so that yarn supporting portion 2b is integral with mechanism enclosing portion 2a thereof. Yarn supporting portion 2b tapers generally toward the right from the right wall of the compartment of portion 2a and is provided with a front-to-back groove 2c on its underside near its tip to provide a passageway for the yarn as shown in FIG. 2.
The compartment in the housing is provided with a number of molded wals and projections hereinafter described for positioning and retaining the elements of the operating mechanism.
The operating mechanism comprises generally the following parts:
1. A toggle (overcenter) spring mechanism for trip lever 12.
2. Adjusting means affording external manual adjustment of the tension of the toggle spring mechanism thereby to select the magnitude of yarn tension at which the switch will trip.
3. A switch operated by the feeler lever.
4. A yarn detector electrical circuit including the switch and a resistor in series.
5. An indicator lamp connected in the yarn detector circuit in series with the switch and in parallel with the resistor.
The toggle spring mechanism is mounted on a bracket plate 16 that lies against the rear wall of the compartment primarily, and has two forwardly bent portions 16a and 16b that lie against the upper wall of the compartment as shown in FIG. 5, and has a downwardly bent portion 16c that lies against the front cover as shown in FIG. 4, this portion 16c being bent down from forward portion 16b to form a pivot for the toggle spring mechanism. This bracket plate is secured to the housing by a pair of rivets including a pivot 18 that is inserted through a hole in the rear wall of the housing and a hole in the bracket plate and is staked within the compartment as shown in FIG. 4 to secure it in place. The other rivet 20 shown in FIGS. 2 and 5 goes through portion 16a of the bracket plate and the upper wall of the housing and serves also to secure combined mounting clip and terminal 8 to the housing as well as securing the bracket plate within the housing compartment.
The bracket plate is provided with a pair of aligned notches for pivoting crank shaft 22. For this purpose, a front notch 16d is provided in portion 16c as shown in FIG. 2 and a like rear notch is provided directly behind it in the main body of the bracket plate that lies against the rear wall of the compartment. These two notches are spaced from one another by the depth of the compartment as shown in FIG. 5 and afford space therebetween for the central swinging portion of crank shaft 22. The opposite ends of the crank shaft extend through holes in the rear wall and front cover and through respective bushings 2d and 4a thereon as shown in FIG. 5. The extreme ends of this crank shaft are flattened to fit into slits in the ends of trip lever 12 to afford turning of the crank shaft by the trip lever in response to undue yarn tension.
A tension spring 24 of the helical type provides the toggle action. The center of the swinging part of crank shaft 22 is provided with a re-entrant bend to form a notch for retaining one end hook of spring 24 as shown in FIG. 5. A fixed but adjustable slide member 26 is provided with a hole as shown in FIG. 4 for retaining the other hook of this spring so that the spring is stressed in tension therebetween.
The aforementioned tension adjusting means comprises slide member 26 and a worm 28 that meshes with a rack 26a on the lower surface of slide member 26. As shown in FIG. 2, the left end portion of slide member 26 is slidably held in a groove between an upper wall 2e and a lower wall 2f integrally molded in the housing. Wall 2e has a forwardly projecting portion 2g at its right end as shown in FIGS. 2 and 5 to form a rest for portion 16c of the bracket plate to retain the latter securely in its place, the remainder of this wall being slightly narrower to provide clearance for the upper end of pointer 30. Worm 28 is tapered to remain in mesh with the slightly angularly-disposed rack 26a. This worm is integral with a horizontal shaft 28a that terminates in an external knob 28b having a hexagonal shape for manual turning. This worm is held in place by a pair of walls 2h and 2j forming a groove therebetween molded in the housing through which groove the worm shaft passes, these walls bearing against the worm and the left wall of the compartment bearing against the knob to hold the worm fixed within the housing. In addition, bracket plate 16 is provided with a forwardly-projecting finger 16e having a tab 16f bent over the tip of the shaft beyond the worm to keep the worm from rising out of its slot in the housing as shown in FIGS. 2 and 4. Another projection 2k integrally molded in the housing is located below this tip of the worm shaft to hold the worm up against and in mesh with the rack. The part of the shaft 28a immediately adjacent the knob also passes through a groove in the left wall of the compartment to hold it fixed but rotatable.
Slide member 26 is provided with a notch in its front edge for retaining the circular upper end of pointer 30 and for rotating this pointer as the slide member is moved by turning the knob. This pointer is pivoted at its intermediate portion on a short round projection 2m integrally molded on wall 2h. A curved wall 2n is molded in the housing directly below the tip of the pointer to make this pointer visible through the transparent cover by providing a light colored background for the black pointer.
The aforementioned yarn detector circuit extends as shown in FIGS. 2 and 8 from mounting clip 8 through its rivet 20, bracket plate 16 and pivot 18 to movable cam contact 32. This circuit then continues from stationary spring contact 34 (shown also in FIG. 6), resistor 36 and connector 38 (also shown in FIG. 7) and the rivet through the rear wall to external connector 40. Lamp bulb 42 is connected between stationary contact 34 and connector 38 in parallel with resistor 36.
As shown in FIG. 4, pivot 18 serves a number of purposes. As hereinbefore described, it serves as a rivet to secure bracket plate 16 to the housing. It also serves as a pivot for the rear arm of feeler lever 14. For this purpose, it is provided with a round bore shown in FIG. 4 extending partway in from its outer end in which the forwardly-bent end of the rear arm of the feeler lever is pivoted and in which the feeler lever is held by its own spring bias. Pivot 18 also serves to pivotally support movable cam contact 32. For this purpose, pivot 18 is provided with a reduced diameter forward end portion that extends into the center hole of the movable contact to freely support the latter for rotation thereon.
Movable contact 32 is thus freely pivoted for engaging stationary spring contact 34. As shown in FIG. 2, movable contact 32 is bowknot shaped having cam segments on opposite sides 180° apart so that either cam can be positioned in assembly for engagement with the stationary contact. The center hole therein is provided with a pair of slots extending toward the cams, respectively, to receive the contact driver finger in either slot when the switch is assembled.
The movable contact driver shaft 44 is shown in FIGS. 1 and 4. It comprises an insulating shaft having an enlarged slotted external head. The shaft extends through a hole and an integral internal bushing 4b in cover 4 and is rotatably secured therein by a C-washer 45 snapped into a groove in the shaft at the inner end of bushing 4b. The inner end of this driver shaft has a driver finger 44a, eccentrically offset from its center, and a leveling surface at its other side with a recess therebetween for accommodating the reduced end of pivot 18. This driver finger enters one of the slots in movable contact 32 and the leveling surface holds the movable contact concentrically on pivot 18 so that when feeler lever 14 pivots counterclockwise, the movable contact will freely rotate to be cammed into sliding engagement with contact spring 34 to close the switch.
The slot 44b in the external head of driver shaft 44 is shaped to retain the front arm of the feeler lever. As shown in FIG. 1, this slot is provided with a central constriction and the end portion of the front arm of feeler lever 14 is provided with a pair of spaced flattened, wider sections entering on opposite sides of this constriction whereby the feeler lever is snapped in and held in place by its own spring bias.
The external head of driver shaft 44 is provided with means for mounting an adjustable counterweight 46. This means comprises a tapped eccentric projection 44c extending from one edge of the head at substantially a 90° angle counterclockwise from and relative to driver finger 44a so that when the driver finger is at the top, the counterweight will extend substantially horizontally to the left. This counterweight is a metal stud treaded at one end to a substantial length for adjustment into or out of eccentric projection 44c of the driver, this adjustment being made by turning the counterweight at screwdriver slot 46a at its other end.
Following along the yarn detector circuit in the direction it was traced above, the next element is stationary contact 34. As shown in FIGS. 1 and 4, the narrow upstanding portion thereof extends down alongside the movable contact where it can be engaged and then takes a 90° turn left where it enlarges to a wider left-hand section as shown in FIG. 6. This wider section has a notch 34a at its rear edge fitting over a complementary lug in the housing below wall 2n to securely retain it in place. Additionally, this left-hand section of contact 34 is held slightly bowed between the lower surface of wall 2n and spaced wall and stud 2p and 2q molded within the base as shown in FIG. 2. Stud 2q has a hole for receiving one rearwardly-bent wire of resistor 36 for mechanically mounting the latter, and contact 34 has a downwardly-angled connector spring finger 34b shown in FIG. 6 pressing on this resistor wire to make an electrical connection to the resistor as shown in FIG. 2. To provide clearance for connection finger 34b, stud 2q is slightly shorter than wall 2p.
The other wire of resistor 36 is connected by connector 38 to external terminal 40. For this purpose, connector 38 has the configuration shown in FIG. 7. It is riveted at its upper end through the rear wall to terminal 40 as hereinbefore described. It extends down along the right wall of the compartment and through the narrow slot between cover-mounting stud 2r and the lower-right corner wall of the housing and then along the bottom wall of the housing terminating in a notch in wall 2p as shown in FIG. 2. A notch 38a is provided in the rear edge of this connector as shown in FIG. 7 to fit over a complementary lug at the root of stud 2q to retain the connector in secure position in the housing. The part of this connector strip directly above corner stud 2r is provided with a clamp for clamping the other wire of resistor 36. For this purpose, the connector strip is provided with a leftward re-entrant bend 38b and a spring finger 38c is sheared from the forward edge and bent at an angle past this bend. This spring finger is then pressed clear of the bend and the resistor wire inserted within the bend and the finger allowed to spring back against the wire to bias it within the bend to make a pressure electrical connection.
The left end of connector 38 is provided with a lamp socket 38d. For this purpose, the connector strip is provided with a round hole having a short slot at its edge as shown in FIG. 7. The edge of this hole is then formed with a gradual angle with one side of this slot formed up and the other side formed down to fit the threads of the lamp bulb. When the lamp bulb is screwed in this socket, the center terminal thereof is pressed against downwardly angled tongue 34c of contact 34 as shown in FIGS. 2 and 6 to connect the trip indicator lamp across resistor 36.
Cover 4 is provided with a pair of lugs 4b and 4c fitting into corresponding notches above lamp 42 and shaft 28a, respectively. Cover 4 is also provided with an integrally molded forwardly extending stud 4d to hold driver shaft 44 from rotating to facilitate assembly of the cover and insertion of driver finger 44a into the slot in the movable contact cam. Cover 4 is further provided with a transparent window 4e through which pointer 30 shows and a scale of numbers along this window to indicate the tension adjustment when the knob is turned.
The housing is provided with an integrally molded forwardly extending stud 2s forming a stop for feeler lever 14. This stop allows movable contact 32 to engage stationary spring contact 34 and to deflect the latter a limited amount for good contact.
As will be apparent from FIGS. 1 and 2, yarn tension trip lever 12 may be moved down or clockwise a small amount whereupon crank shaft 22 passes the line of action of spring 24 to snap lever 12 all the way. Lever 12 stops when crank shaft 22 abuts the upper wall of the housing. The yarn may then be placed across the bend of lever 12 and this lever moved up or counterclockwise until it snaps over-center into the position shown in FIG. 2. In thus moving up, the yarn carries feeler lever 14 along with it so that the feeler lever rests on the yarn. Thus, the yarn will pass between the upward re-entrant bend in bracket 10 and the downward re-entrant bend in trip lever 12 and below feeler lever 14.
In the case of a snag in the yarn or undue tension or the like, the yarn will pull trip arm 12 down until it will snap over-center. This allows feeler arm 14 to fall clockwise to close the switch to stop the knitting machine and light the indicator lamp.
In case of undue slack in the yarn, or breakage, or end of yarn, feeler arm 14 falls and closes the switch with the same result as above.
As will be apparent, the parts that wear are readily replaceable. Bracket 10 is inserted at its left end in a notch 2t in the bottom of the housing adjacent the indicator lamp and its right ends are bent toward one another and snap into holes 2u in the right end yarn supporting portion 2b of the housing. When this bracket wears by rubbing of the yarn thereon, its ends can be spread apart clear of holes 2u and the bracket removed and readily replaced with a new one.
Feeler arm 14 is also readily replaceable should it wear by rubbing of the yarn. Its rear arms can be spread apart so that the forwardly-bent end on its rear arm clears the hole in pivot 18 (FIG. 4) and its front arm clears the slot in the head of driver shaft 44 (FIG. 1). A new feeler lever can readily be assembled in its place.
Similarly, trip lever 12 is readily replaceable should it wear by the yarn running thereover. Its two arms can be spread apart clear of the ends of crank shaft 22 and the lever removed and replaced with a new one.
As will be apparent from FIG. 1, counterweight 46 is readily adjustable by inserting a screwdriver into slot 46a and turning the counterweight in or out. Its effective weight varies with the length of its horizontal lever arm from the axis of the driver shaft. Its applied counterweight decreases as the feeler lever falls to enhance closing of the switch. As this feeler lever falls, its counterweight is carried clockwise above the axis of the driver shaft so that the horizontal projection of its lever arm decreases in length thereby to decrease the counterweight.
While the apparatus hereinbefore described is effectively adapted to fulfill the objects stated, it is to be understood that the invention is not intended to be confined to the particular preferred embodiment of upper yarn detector switch disclosed, inasmuch as it is susceptible of various modifications without departing from the scope of the appended claims.