US3485980A - Dual link switch actuator - Google Patents

Description

Dec. 23, 1969 J. L. MARTIN DUAL LINK SWITCH ACTUATOR 2 Sheets-Sheet 1 Filed Jan. 19, 1968 O O O O INVENTOR JOHN L. MARTIN (Z 2M M ATTORNEYS Dec. 23, 1969 J. L. MARTIN DUAL LINK SWITCH ACTUATOR 2 Sheets-Sheet 2 Filed Jan. 19, 1968 INVENTOR JOHN L. MARTIN ATTORNEYS United States Patent 3,485,980 DUAL LINK SWITCH ACTUATOR John L. Martin, Wayne, Mich., assignor to Ajem Laboratories, Inc., Livonia, Mich. Filed Jan. 19, 1968, Ser. No. 699,080 Int. Cl. HOlh 3/02 US. Cl. 200-153 10 Claims ABSTRACT OF THE DISCLOSURE Disclosure is directed to an electric switch and operating mechanism therefor which is adapted for more universal application to control starting, stopping, limiting, part sensing and the like and comprises parallel links pivotally mounted at one end on a fixed support and mounting an operating element at the opposite ends and which is adapted to be mounted in reversible positions for spring, gravity or weight operation by a movable element to be controlled located either adjacent to or remote from the switch operating mechanism.

The present invention relates to electric circuit makers and breakers and more particularly to improvements in electric control switches and operating mechanism therefor.

In installations where automation equipment is employed for the transfer and handling of parts, control mechanism usually includes starting switches, limit switches, safety switches and sensing switches for 10- cating parts and the like. Such switches many times include a sensing element or probe in the form of short or long rods engaged by the workpiece. Such rods are apt to be bent, or gradually deformed during use, so that they fail to actuate the control switch as the exact time required to perform a particular function, such as accurately locating a workpiece. Spring loaded pistons also have been used which are actuated by the workpiece to close or open a switch, but this type of switch operator is apt to fail with continuous use over a period of time. Also, the switches themselves many times comprise contacts of a flexible metal, which is apt to fail or become fouled with dirt which prevents proper operation.

In the past, a wide variety of switches and switch actuating mechanisms of different designs have been used for controlling different operations in a single automation installation or the same operation in different installations. These different kinds of switches lack the unity of design characteristics and ruggedness for interchangeable use to consistently perform reproducible results after long periods of time. Because of this lack of uniformity or standard of design characteristics, those required to perform particular functions are apt to be quite expensive.

One of the objects of the present invention is to provide an improved switch and switch operator which is adapted for more uniform use in performing different functions in automation equipment.

Another object is to provide an improved switch and switch operator which may be relied upon to consistently reproduce the same results after repeated operations.

Still another object is to provide a switch and switch operator of the type indicated which is of simple and compact construction, economical to manufacture, adapted for interchangeable use for different control functions and one which is adjustable relative to a moving part to be sensed.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only Patented Dec. 23, 1969 and are not a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings:

FIG. 1 is a side view of a reversible conveyor controlled by limit switches incorporating novel features of the present invention;

FIG. 2 is an elevational view of the apparatus illustrated in FIG. 1 and showing the actuator on the conveyor engaging a sensing element of the switch operator at a location remote therefrom;

FIG. 3 is a view of the switch operator as illustrated in FIG. 1, but so arranged as to be biased by gravity to open position;

FIG. 4 is a view similar to FIG. 1 and showing the switch operating mechanism biased to open position by a counterweight;

FIG. 5 is a front view of an adapter plate for adjusting the operating linkage relative to the part to be sensed; and

FIG. 6 is an end elevational view showing the adapter plate mounted on a support and the operating linkage adjustably mounted on the adapter plate.

The switch and switch operating mechanism of the present invention may be used to perform difficult functions such as a starting switch, limit switch, safety switch, locating switch and the like. For purposes of illustration, however, a pair of mechanisms 5 and 6 incorporating the novel features of the present invention are shown for controlling the reversal of a conveyor 7.

The continuous conveyor comprises a plurality of articulated links 8 and is mounted for movement on spaced sprockets 9 and 10. Conveyor 7 is intended to move first in one direction for a predetermined distance and then reverse its direction to move in the opposite direction and the direction of movement is controlled by a cam 11 for actuating the switching operating mechanisms 5 and 6. It will be understood that one of the sprockets 9 or is driven by an electric motor, not shown, as controlled by the switches 5 and 6.

As the reversing switch mechanisms 5 and 6 are identical, a description of one will include the other. As shown, each reversing switch mechanism 5 and 6 comprises a frame 13 adjacent the conveyor 7 and has a switch housing 14 mounted thereon and enclosing a switch 15. The switch 15 may be of any suitable construction for operation by a lever 16 pivotally mounted on the housing at the exterior thereof. In the illustrated embodiment, however, a mercury type switch 15 is shown having an envelope 17 with terminals 18 and 19 and containing a body of mercury 20 constituting a movable contact. Switch 15 is mounted on a shaft 21 rocked by lever 16 and biased to the open position illustrated in FIG. 1 by a spring 22 in which position the body of mercury 20 is at the right hand of the envelope as shown. However, when the switch 15 is tilted counterclockwise by lever 16 against the action of spring 22 the body of mercury 20 flows across the contacts 18 and 19 to a switch closing position. As shown, the switch operating lever 16 has a roller 23 at its outer end. The enclosure of the switch contacts 18, 19 and 20 within the envelope 17 and the location of the entire switch 15 in housing 14 reduces the possibility of malfunction or failure due to an accumulation of dust or dirt around the contacts or operating mechanism.

Each of the reversing switch mechanisms 5 and 6 comprises a pair of generally parallel links 26 and 27 having one of their ends pivotally mounted on fixed pivot pins 28 and 29. The opposite ends of the links 26 and 27 are pivotally connected to each other by a movable link 30 and pivot pins 31 and 32 for movement in unison. To provide a more rigid structure a second movable connecting link 30a is mounted on the pins 28 and 29 and held in spaced relation to the link 30 by spacing sleeves 30b. The fixed pivot pins 28 and 32 project laterally from a fixed link type element 33 permanently attached to the frame 13 as by the welding. Preferably, the fixed element 33 and movable link 30 are of a construction used in chains because of their availability as standard parts, but it will be understood that the links may take other forms.

A spring 34 is connected between fixed and movable parts of the linkage of the switch for yieldingly biasing the linkage at the left hand side of the apparatus to the position illustrated in FIG. 1. In the illustrated embodiment the spring is connected between extensions of the fixed and movable pivot pins 28 and 32. Pivot pin 31 has an extension 31a constituting a sensing element for engagement by the control cam 11 depending from conveyor 7 to actuate the limit switch 6 to the position shown in the right hand side of FIG. 1. It will be observed by reference to FIG. 2 that the control cam 11 engages the sensing element or extension 31a at a location remote from the linkage to permit free operation thereof.

A block 35 is permanently attached to the connecting links 30 and 30a as by means of a welded joint 36 and the block projects laterally beyond the links as illustrated in FIG. 2. A switch actuator 37 is mounted in the block 35 and has a head or button 38 at its end which overlies the roller 23 of the switch arm 16. The actuator 37 is shown in the form of a threaded stem rotatably mounted in a tapped hole 40 in the block 35 for adjusting the initial position of the button 38 with respect to the switch operating arm 16 by turning the switch actuator in the block. A lock nut 41 is provided for clamping the switch actuator in any particular adjusted position with respect to switch 15. One form of construction having now been described in detail, the mode of operation is now explained.

For purposes of illustration, let it be assumed that with the parts of the reversing switch mechanisms and 6 in the position illustrated in FIG. 1, the limit switch of mechanism 6 at the right hand side of the apparatus has been operated to a circuit-closing position, that the switch is connected to a motor for reversing the direction of rotation of the driving sprocket 9 and that the lower run of conveyor 7 and control cam 11 have started to move toward the left. As the control cam 11 moves toward the left it releases the sensing element 31a projecting late-rally from the pivot pin 31 so that the spring 34 acting between the pivot pins 28 and 32 will move them toward each other and rock the parallel links 26 and 27 upwardly from the position shown. The block 40 attached to the links and 30a also will move upwardly and carry the switch actuator 37 to release the switch arm 16. Spring 22 will then rock arm 16 on shaft 21 and mercury switch 15 to an open circuit position as shown at the left hand side of the apparatus, However, a holding circuit, not shown, will maintain the driving motor energized to continue operation of the lower run of conveyor 7 toward the left. When the control cam 11 engages the laterally project- 1ng sens ng element 31a of the reversing switch operating mechanism 5 it will move the linkage including link 30 downwardly against the action of the spring 34. Such downward movement of the link 30 and block projectmg therefrom will cause the switch actuator 37 to rock the pivoted actuating arm 16, shaft 21 and mercury switch 15 mounted thereon to a circuit closing position. Closing of the switch 15 will energize a circuit to reverse the directlon of the motor for driving the conveyor 7 and cause t to reverse its direction and move back to the position illustrated in FIG. 1.

FIG. 3 illustrates a modified arrangement of the switch 15 and its operating linking illustrated in FIG. 1, to normally bias the switch to an open circuit position by gravlty and move it to a circuit closing position by cam operator 11. To this end the entire switch 15 and its operating mechanism are turned up-side-down so that the switch is positioned above its operating mechanism. As shown, the pair of movable links 26 and 27 are located to the right of the fixed element 33 having the fixed pivot pins 28 and 29. Thus, the weight of the links 26 and 27 plus the weight movable link 30, block 35 and switch actuator 37 offset at one side of fixed pivot pins 28 and 29 cause the linkage to rock to its lowermost position by gravity. The control cam 11, however, will move the linkage upwardly against the action of gravity to the dotted line position illustrated to actuate the switch 15 to a circuit closing position. However, as soon as the control cam 11 is moved away from and releases the sensing element 31a, the linkage will be moved to an open circuit position.

FIG. 4 illustrates a still further modified construction in which the switch operating link is normally biased to an open circuit position by means of a counterweight 42. In this modified construction the switch 15 and its operating linkage is the same as that shown on the left hand side of the apparatus illustrated in FIG. 1. The movable link 26, however, has the counterweight '42 extending to the right hand side of its pivot pin 28, and is of such a size and weight as to overbalance the weight of the links 26 and 27, movable link 30, block 35 and switch actuator 37, to normally hold it in a raised position. It will be understood, however, that the counterweight 42 may be arranged as an extension of the movable link 27. Such an arrangement as illustrated in FIG. 4 operates in substantially the same way as the switch arrangement illustrated in FIG. 1.

FIGS. 5 and 6 illustrate a further modification in construction for mounting the switch operating mechanism 5 or 6 for adjustment relative to the control element 11 to be sensed. The adjusting means comprises an adapter plate 50 mounted On a fixed part or frame 51 of the machine and, in turn, adjusta'bly mounting the switch operating mechanism '5 or 6. To this end, the plate 50 has a longitudinally extending slot 52 in one face into which the edge of a bracket 53 projects and to which it is attached by a fastening screw 54. Bracket frame 53 is similar to the bracket frame 13 illustrated in FIGS. 1 to 4, except that it is of short length. As shown, the edge of the bracket 51 closely fits the slot 52 which will prevent rotation and permit the bracket to be attached to the plate by a single fastening screw 54. As will be observed by reference to FIG. 5, the adapter plate '50 has a plurality of spaced holes 55 in the slot 52 to adapt the bracket 53 and switch operating mechanism 5 or 6 to be adjusted bodilyalong the plate by sliding the bracket along the slot. The adapter plate 50 also is provided with spaced holes 56 for mounting the switch housing 14 thereon in different positions of adjustment relative to the bracket 54.

It will now be observed that the present invention provides a standard switch having a more universal use for different applications in material handling apparatus of automation equipment. It will also be observed that the present invention provides a switch and its operating mechanism which performs reproduceable results after repeated operations with a greater degree of reliability than conventional switches. It will still further be observed that the present invention provides a switch and switch operating mechanism which is of simple and compact construction, economical to manufacture, adapted for a great number of different uses with little if any modification for special functions, and one which may be adjusted relative to the control element of a mechanism to be controlled.

While several embodiments of the invention are herein illustrated and described, it will be understood that further changes may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect, the invention is defined by the following claims.

What is claimed is:

l. In a switch of the type having relatively movable contacts biased toward one of its open and closed positions and movable toward the other position and a movable element connected to actuate the contacts toward said other position, the combination with said switch of an operating mechanism comprising a pair of generally parallel links having one end connected to fixed pivot pins, a link pivotally connecting the other ends of the parallel links, an actuator projecting from a movable part of the linkage for actuating the movable element connected to actuate the switch contacts toward said other position, and a sensing element projecting from the movable linkage for engagement by a movable part to be controlled at a position remote from the linkage to actuate the switch contacts.

2. A switch having a movable contact for closing a circuit in one position and opening a circuit in another position, a pair of links mounted on fixed pivot pins at one end, a link pivotally connecting the opposite ends of the pair of links to each other, a sensing element for sensing movement of a part and connected to actuate at least one of the pair of links, an actuator projecting from a movable part of the linkage for actuating the movable contact of the switch, and means for biasing the linkage to disengage the actuator upon release of the sensing element by the movable part.

3. A switch in accordance with claim 2 in which the actuator is a threaded rod rotatable in a tapped hole in a block mounted on the movable connecting link, and a lock nut on the threaded rod for locking the actuator in adjusted position on the block.

4. A switch in accordance with claim 2 in which the fixed pivot pins for the pair of links are mounted in a rigid element of the linkage and said fixed element and switch being attached to a frame bracket in adjacent relation.

5. A switch in accordance with claim 2 in which a spring is connected between a fixed and movable part of the linkage to bias the switch actuator to one of its positions.

6. A switch in accordance with claim 2 in which the pair of movable links is so arranged with respect to the movable contact of the switches to bias the actuator to one of its positions by gravity.

7. A switch in accordance with claim 2 in which a counterweight is attached to the linkage and located at the opposite side of the fixed pivot pins from the movable links to bias the switch actuator to one of its switch posi tions.

8. A switch in accordance with claim 7 in which the counterweight is an extension of one of the pivoted links beyond its fixed pivot.

9. A switch in accordance with claim 2 in which the fixed pivots for the pair of links are mounted on a frame bracket, an adapter plate mounted on the fixed frame between the latter and the frame bracket, and adjusting means for mounting the frame bracket at different positions on the adapter plate.

10. A switch in accordance with claim 9 in which the adapter plate has a slot in one side, the frame bracket has an edge closely fitting the slot to adapt the bracket to be adjusted on the plate by sliding it along the slot, a series of spaced holes in the slotted portion of the adapter plate, and a fastening Screw extending through one of the holes and screwed into the edge of the bracket to mount the switch operating mechanism in adjusted position on the plate.

References Cited UNITED STATES PATENTS 3,439,!34 4/1969 Carli 200-47 ROBERT K. SCHAEFER, Primary Examiner D. SMITH, JR., Assistant Examiner US. Cl. X.R.

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