US3808453A

US3808453A - Compactor interlock control

Info

Publication number: US3808453A
Application number: US00279985A
Authority: US
Inventors: E Engebretsen; V Schuerman
Original assignee: Hobart Manfacturing Co
Current assignee: Whirlpool Corp
Priority date: 1972-08-11
Filing date: 1972-08-11
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: CA992796A

Abstract

A compacting machine has a reversible motor drive for a ram movable in a compacting stroke and a retracting stroke. Directional controls prepare the drive for a compacting stroke when the ram is at its fully retracted starting position and prepare the drive for a retracting stroke as soon as the ram leaves the starting position. A safety switch prevents operation of the ram unless the door is closed and the receptacle in compacting position. This switch is by-passed once the ram enters the receptacle to avoid unnecessary stopping of the compacting cycle. When the ram encounters a predetermined resistance it automatically reverses.

Description

United States Patent [1 1 Engebretsen et al;

[ 51 Apr. 30, 1974 COMPACT OR INTERLOCK CONTROL Inventors: Einar O. Engebretsen; Victor F. Schuerman, both of Troy, Ohio Assignee: The Hobart Manufacturing Company, Troy, Ohio Filed: Aug. 11, 1972 Appl. No.: 279,985

us. c|.....- 307/112, 100/52 Int. Cl. 1330b 15/14 Field of Search 100/52, 50, 53; 307/117, 307/112, 149, 119, 120, 92; 318/207 C, 207 R, 207 A Raeam Cited UNITED STATES PATENTS Bottas 100/52 Primary Examiner-Herman J. Hohauser Attorney, Agent, or Firm-Biebe1, French & Bugg [57] ABSTRACT A compacting machine has a reversible motor drive 7 fora ram movable in a compacting stroke and a retracting stroke. Directional controls prepare the drive for a compacting stroke when the ram is at its fully retracted starting position and prepare the drive for a retracting stroke as soon as the ram leaves the starting j. position. A safety switch prevents operation of the ram unless the door is closed and the receptacle in compacting position. This switch is by-passed once the ram enters the receptacle to avoid unnecessary stopping of the compacting cycle. When the ram encounters a predetermined resistance it automatically reverses.

3 Claims, 4 Drawing Figures DlRECTION SWITCH 8O PATENTEDAPR 30 IQYL FIG -1 RETRACTED 5O POSITION OF LATCH 4 5 6 m m D F E Tm T Al Rm UP R 2 5 M, m; I w w M 2 D 4 F 6 O 3 N m h m DIRECTION SWITCH I 1 I COMPACIOR INTERLOCK CONTROL CROss REFERENCE TO RELATED APPLICATIONS This application is related to copending U. S. application Ser. No. 224,897, filed Feb. 9, 1972, entitled COMPACT OR, and U. S. application Ser. No. 279,984, filed concurrently herewith, entitled COM- PACTOR CYCLE CONTROL, both assigned to the assignee of this application.

BACKGROUND OF THE INVENTION This invention relates to trash compacting machines and the like, and particularly to the controls for a reversible electric motor driving a compactingram in such a machine. The trash receiving receptacle is connected to the access door such that the door is closed whenever the receptacle is in compacting position. Such machines have safety interlock controls which prevent movement of the ram from its retracted position unless the receptacle is properly located under the ram with the door closed. In actual use, relatively slight movement of the receptacleand/or door has caused the interlock to stop the motor. This may be caused, for example, by force components due to the compacting of trash items at one side of the receptacle. Due to ordinary manufacturing tolerances and/or wear, only a slight such movement may open the interlock and stop the machine. However, if the operator cannot then push the door in sufficiently to close the interlock, he must call for service to free the machine.

Attempts have been made to rectify this problem, as by adding a further'interlock switch which allows some additional movement-of the door and receptacle once the compacting cycle is under way. Such an arrangement is disclosed in U. S. Pat. No. 3,613,560. However, a simpler solution to the situation is desirable.

SUMMARY OF THE INVENTION A control for a reversible electric motor driving the ram of a compactor, includes a starting circuit with a manually operable starting switch which is closed only long enough to energize a holding circuit which continues power supply to the motor. A directional switch is responsive to ram location at its retracted limit, also the cycle starting position, and is moved to cause forward (compacting) motor operation only when the ram is at this position. When the ram leaves its starting position the directional switch transfers to reverse or retracting connections preparatory to any slowing of the motor to a speed where its centrifugal starting switch will again close.

A cycle ending switch is arranged to respond to ram movement only in the retracting direction and as the ram approaches its starting position, at which time this switch is actuated momentarily. The cycle ending switch is wired to open the holding circuit when it is momentarily actuated, hence power to the motor is terminated as the ram approaches the starting position at the end of the.retracting stroke. The ram and motor coast to a stop, by which time the startingposition is reached and the directional switch is moved to the forward starting position, and the cycle ending switch is again closed.

A safety door interlock switch and a key switch are provided to assure the machine can be operated only 7 receptacle and until the'ram has partially entered the receptacle, for example to a depth of about 1 inch. Since the ram exterior is generally configured to the interior of the receptacle, once the ram has entered the receptacle it prevents the door from being opened. Any slight movement of the receptacle and door, even enough to open the door interlock switch, will not affect completion of the compacting cycle.

The principal object of the invention is thus to provide such a compacting machine with a control of the above described type, in which a compacting cycle can be initiated only when the. safety interlock is closed, but can proceed through a cycle once the ram has entered the receptacle and the door cannot be opened, even though the receptacle and door may move slightly and possibly open the interlock; and in which, following stopping of the ram in its compacting stroke for any reason, subsequent ram movement will automatically be in the reverse direction to thestarting position.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the compactor showing the receptacle thereof in both its compacting and non compacting positions;

FIG. 2 is an enlarged view of a portion of the rear of the compactor with some parts broken away to shorten the view;

FIG. 3 is a representation of a wiring diagram of the present invention; and

FIG. 4 illustrates the manner in which the direction switch and cycle ending switch are operated in relation to ram movement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS in FIG. 1.

A ram 16 is also positioned in the housing and carries a motor 18 which, through a suitable drive chain, drives sprockets 20 to cause the entire ram mounted assembly to move upwardly and downwardly along the stationary jack screws-22. Preferably, three such jack screws will be utilized, arranged in triangular relationship with two jack screws positioned adjacent the front of the housing and one jack screw positioned centrally adjacent a rear wall of the housing.

starting and reversing control (FIG. 3) which will automatically initiate a compacting stroke of the ram, and

will cause the ram to retract to its inactive position after some predetermined load is imposed on the motor as it drives the ram in the compacting stroke.

Mounted on a rear surface of the drawer 14, as seen in FIG. 2, is an angle shaped strike member 28 having a slot 30 formed through its rearwardly projecting bottom leg 34. An inverted U-shaped bracket 36 is attached to the housing adjacent the rear thereof and carries a substantially T-shaped latch member 40 rotatably mounted on a bolt 42 extending through the bracket. The latch member has a downwardly projecting stem 44 receivable in the slot 30. A spring 45 acts between bracket 36'and latch member 40. A portion of the base 15 is also provided with a slot 48 which aligns with the slot 30 when the receptacle 14 is in the compacting position.

As seen in FIG. 2, the ram 16 is provided with an L- shaped bracket 50 projecting to one side thereof and connecting rod 52 has its lower, forwardly bent end 53 rotatably received in an opening formed in latch 40. The connecting rod is loosely received in an opening formed through the bracket 50 and has its upper end bent at an angle to form a stop member 54. By properly proportioning the length of the connecting rod 52, the latch member 40 will be pulled upward about its pivot such that it clearsthe slot 30 in member 28 when the ram 16 is in its retracted or withdrawn position as shown in FIG. 1. However, a small initial movement of the ram 16 toward the receptacle will permit the latch to be urged by spring 45 into

slots

30 and 48, locking the receptacle 14 in the compacting position within the housing. 8

While the receptacle 14 is locked in position during compacting initial movement of the ram, access may still-be had to the interior of the compactor through the upper access door 55. Waste material, particularly small items such as milk cartons, bottles, cans, etc., can be deposited in the compactor, where they will rest in a small compartment-formed by the inclined shelf 57 and the protective wall 58, until such time as the receptacle l4 is moved outwardly of the housing. This will allow articles lying on shelf 57 to fall into the receptacle 14. The user, therefore, need not wait until the receptacle is unlocked to deposit material in the compactor, but he is of course protected against injury, etc., during operation of the ram by the wall 58.

A safety interlock switch-60, the'housing for which is shown at 61, is mounted inside the front of the housing, as seen in FIG. 1, and is engaged by a pin 62 when the receptacle 14 is in its compacting position.

A further interlock is provided by the normally closed switch 65 which is wired in parallel with switch 60. Switch 65 is operated by a bracket 66 (FIG. 4) carried by ram 16, and arranged such that the switch is opened when the ram lower surface 24 is just below or within the upper edge 26 of the receptacle, for example within about one'inch of the edge 26. In other words,

switch 65-is closed only when the ram has entered the receptacle and thus acts to prevent the drawer unit from being opened, intentionally or accidentally.

' Thus,once the ram is inside the receptacle, which is attached to the door and drawer unit, the door 13 cannot be opened by the operator. However any motion of the receptacle and drawer unit, as might occur from off-center froces during compacting, to open the switch 60, will not stop the compactingcycle. This minimizes the need to hold close manufacturing tolerances on the actuator for switch 60, yet keeps the machine fully protected. It also minimizes nuisance-.typeservice calls from persons unable to withdraw the ram when ithas forced the door interlocks open and the person cannot push the drawer unit closed enough to start it again.

Referring to FIG. 3, the control system is shown. Interlock switch 60 is closed when drawer .14 is closed, and it controls all power to the unit together with key switch 70. Contacts are shown in the position with the drawer open, the ram up, motor stopped, and the key safety switch open. With the key switch 70 operated to close, and the drawer closed, pushing the start button on starting relay 76 will close'its contact 77 and energize its coil 78 to seal'in the relay. This also applies power to the starting winding 80 of ram motor 18,

through the motors centrifugal starting switch 81, and.

through the contacts of a directional switch 84. The power circuit is completed to main winding through the overload protector 86. I

The holding circuit for relay 76 includes its coil 78, manual stop switch 88 which is normally closed, a normally closed ram operatedswitch 90, and the overload protector 86. Switch 90 is arranged to be opened momentarily by the ram only when it is nearing'the top of its return stroke. Its operating lever 92 has an outwardly extending arm 93 pivoted thereon, normally held by a spring 94 in the extended position as shown.

A roller 95 on the arm is in position to engage an arm 97 extending from the ram 16. On the downward stroke switch 90 is unaffected and remains closed, but on the upwardly retracting stroke the switch is momentarily opened just as the ram approaches its fully retracted position. Directional switch 84 is carried by the ram and is held in the position shown only when the ram is fully up. When the ram'is in any other position, the blades of switch 84 transfer to the contacts shown open. 1 Y I i Thus, as power is first applied the motor 18 starts in a direction to lower the ram in a compactingstroke. The motor immediately comes up to speed, since it is under a slight load, and switch 81 opens and transferring of thecontacts of switch 84 has no effect on motor motor coasts to a stop past the actuation positon of switch 90, so that it again closes. Switch 84 is moved to the positon shown, such that the circuit is ready for I the next compacting stroke, just before switch 90 is actuated. I I

After a compacting stroke begins switch 65 closes, bypassing interlock'switch 60 since the ram is now inside the receptacle and latch 40 is engaged. Thereafter,

if stop switch 90, or key switch 70, is opened, or the motor overload protector 86 opens, the circuit energizing relay 76 will be broken, and the motor will stop. Subsequent operation of the start button 75 will energize the motor to drive the ram upward, provided the appropriate switch contacts are then closed.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. A control for a compacting machine having'a receptacle for trash material and a door connected to said receptacle such that said door is closed when said receptacle is in a compacting position, a ram mounted for compacting movement in a compacting stroke entering said receptacle and an opposite retracting stroke to a retracted starting position, a power supply, a reversible motor connected to drive said ram, a directional switch connected to control the forward and reverse operation of said motor corresponding to the compacting and retracting strokes of said ram, means normally holding said directional switch in its reverse position, a starting switch connected betweenvsaid directional switch and said power supply, and an interlock operable in response to opening of said door to disconnect said motor from said power supply;

the improvement comprising means for bypassing said interlock once said ram has entered said receptacle in a compacting stroke until said ram is almost withdrawn from said receptacle in a retracting stroke.

2. A control as defined in claim 1, wherein said motor is an electric motor with a starting winding, a motor speed responsive switch controlling said starting winding, a main winding, and said directional switch is conriected to reverse the phasing of said starting winding with respect to said main winding, said interlock including a door operated switch connected in series circuit with said starting switch, said power supply, and said main winding, said bypassing means including a normally closed bypass switch connected in parallel with said door operated switch and held open by said ram whenever said ram is at the top of or withdrawn from said receptacle.

3. A control for a trash compacting machine having a receptacle, a door, a drawer unit incorporating said door and said receptacle for joint movement between a closed compacting position and an open position, a ram mounted for movement with said drawer unit in the closed position in a compacting stroke to compact material and an opposite retracting stroke to a retracted starting position, a power supply, a reversible electric motor connected to drive said ram, and including a motor speed responsive switch and a starting winding, a directional switch connected to switch the power supply to said starting winding for forward and reverse operation corresponding to the compacting and retracting strokes of said ram, a starting circuit connecting said directional switch to said power supply and including a starting switch,

means operated by said ram for moving said directional switch to its forward position only when said ram is at its starting position, an interlock switch connected between said motor and said power supply and operative to supply power to said motor only with said drawer unit in said closed position; the improvement comprising a switch connected to bypass said interlock switch and operated by said ram during compacting and retracting strokes to close only when at least a portion of said ram is within said receptacle.

Claims

1. A control for a compacting machine having a receptacle for trash material and a door connected to said receptacle such that said door is closed when said receptacle is in a compacting position, a ram mounted for compacting movement in a compacting stroke entering said receptacle and an opposite retracting stroke to a retracted starting position, a power supply, a reversible motor connected to drive said ram, a directional switch connected to control the forward and reverse operation of said motor corresponding to the compacting and retracting strokes of said ram, means normally holding said directional switch in its reverse position, a starting switch connected between said directional switch and said power supply, and an interlock operable in response to opening of said door to disconnect said motor from said power supply; the improvement comprising means for bypassing said interlock once said ram has entered said receptacle in a compacting stroke until said ram is almost withdrawn from said receptacle in a retracting stroke.

2. A control as defined in claim 1, wherein said motor is an electric motor with a starting winding, a motor speed responsive switch controlling said starting winding, a main winding, and said directional switch is connected to reverse the phasing of said starting winding with respect to said main winding, said interlock including a door operated switch connected in series circuit with said starting switch, said power supply, and said main winding, said bypassing means including a normally closed bypass switch connected in parallel with said door operated switch and held open by said ram whenever said ram is at the top of or withdrawn from said receptacle.

3. A control for a trash compacting machine having a receptacle, a door, a drawer unit incorporating said door and said receptacle for joint movement between a closed compacting position and an open position, a ram mounted for movement with said drawer unit in the closed position in a compacting stroke to compact material and an opposite retracting stroke to a retracted starting position, a power supply, a reversible electric motor connected to drive said ram, and including a motor speed responsive switch and a starting winding, a directional switch connected to switch the power supply to said starting winding for forward and reverse operation corresponding to the compacting and retracting strokes of said ram, a starting circuit connecting said directional switch to said power supply and including a starting switch, means operated by said ram for moving said directional switch to its forward position only when said ram is at its starting position, an interlock switch connected between said motor and said power supply and operative to supply power to said motor only with said drawer unit in said closed position; the improvement comprising a switch connected to bypass said interlock switch and operated by said ram during compacting and retracting strokes to close only when at least a portion of said ram is within said receptacle.