US3866825A

US3866825A - Motion sensing lock for securing a cover or guard for a rotatable member such as a centrifugal contactor shaft

Info

Publication number: US3866825A
Application number: US308967A
Authority: US
Inventors: Richard J Balazer; Administrator James A Farrand
Original assignee: Baker Perkins Inc
Current assignee: Baker Perkins Inc; APV Chemical Machinery Inc
Priority date: 1972-11-24
Filing date: 1972-11-24
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18

Abstract

A cover or guard for a machine having a rotatable member such as a shaft is secured by a lock having a motion sensing probe which prevents opening of the cover if the rotatable member is in motion. The motion sensing probe extends to a position of proximity with the rotatable member or shaft and may be moved from an ''''at rest'''' position in which the probe is spaced from the rotating part in a direction to engage the rotating part, and wherein probe controlled mechanism, maintaining the lock in locked position when the probe is ''''at rest'''', is operable to disable the lock only if the rotatable member is not rotating when engaged by the motion sensing probe.

Description

United States Patent Balazer, deceased et a1.

MOTION SENSING LOCK FOR SECURING A COVER OR GUARD FOR A ROTATABLE MEMBER SUCH AS A CENTRIFUGAL CONTACTOR SHAFT Inventors: Richard J. Balazer, deceased, late of Saginaw, Mich.; James A. Farrand, administrator, Saginaw, Mich.

Assignee: Baker Perkins, Inc;, Saginaw, Mich.

Filed: Nov. 24, 1972 Appl. No.: 308,967

[ Feb. 18, 1975 2,955,693 10/1960 Renault et al. 192/136 FOREIGN PATENTS OR APPLICATIONS 442,309 2/1936 Great Britain 210/146 Primary ExaminerGeorge H. Krizmanich Attorney, Agent, or FirmLearman & McCulloch [57] ABSTRACT A cover or guard for a machine having a rotatable member such as a shaft is secured by a lock having a motion sensing probe which prevents opening of the cover if the rotatable member is in motion The motion sensing probe extends to a position of proximity with the rotatable member or shaft and may be moved from an at rest position in which the probe is spaced from the rotating part in a direction to engage the rotating part, and wherein vprobe controlled mechanism, maintaining the lock in locked position when the probe is at rest, is operableto disable the lock only if the rotatable member is not rotating when engaged by the motion sensing probe.

14 Claims, 6 Drawing Figures PATENTEDFEB18I9Y5 7 SHEET 10F 2 MOTION SENSING LOCK FOR SECURING A COVER OR GUARD FOR A ROTATABLE MEMBER SUCH AS A CENTRIFUGAL CONTACTOR SHAFT BACKGROUND OF THE INVENTION Government regulations relating to the design of machinery are today concerned with the safety of the machine operator and seek to prevent him from being injured even when he is negligent in the handling and operation of the machinery. Thus, there is a considerable need for a simple and inexpensive cover lock for rotating equipment such as centrifuges.

One of the prime objects of the present invention is to design a motion-sensing lock which normally maintains a cover for a rotatable part in locked position and permits it to be opened only at a time when the shaft or other rotatable part is stationary.

A further object of the invention is to design a simple and compact mechanical motion sensitive and responsive lock of the type described, which can be unlocked only if the operator physically moves the lock into engagement with the rotatable part at a time when the rotatable part is stationary.

Still another object of the invention is to provide a mechanically operated, fail-safe lock incorporating a shaft engaging probe which is moved to collapsed position if the shaft is rotating when the probe engages it.

Another object of the invention is to provide a device of the character described which will find wide use in industry on myriad devices of all types including, for example, machine tools, power-driven yard and shop equipment, and even various household appliances.

Another object of the invention is to provide a lock of the type described which avoids the use of electrical circuitry and the explosion-proof enclosures rendered necessary to house the circuitry on some equipment.

A final object of the invention is to provide a highly reliable sensing device which can be very economically manufactured and assembled.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings, in which:

FIG. 1 is a partly sectional, somewhat schematic view showing a machine having a cover for a rotatable part which is latched by a lock constructed according to the present invention;

FIG. 2 is an enlarged, fragmentary elevational view, taken on line 2-2 of FIG. 1;

FIG. 3 is a considerably enlarged, fragmentary side elevational view of the lock or latch mechanism illustrating the parts with greater clarity;

FIG. 4 is a partly sectional, side elevational view with the lock device shown in the at rest position;

FIG. 5 is a similar view with the lock mechanism shown as moved to engage the probe with a shaft at the time the shaft is stationary; and

FIG. 6 is a similar view showing the position of the lock parts at a time when the lock probe is moved to engage a rotating shaft and is pivoted thereby to a partly displaced position.

Referring now more particularly to the accompanying drawings in which only a preferred embodiment of the invention has been shown, and in the first instance more particularly to FIG. 1, a numeral 10 generally indicates the frame of a machine which has suitable bearings for mounting a rotatable member such as a rotor 11 which is schematically depicted. The base 10 in-- cludes a front wall 12 and a rear support bar 13, and a semi-cylindrical cover 14 is hinged to the bar 13 in any suitable manner, as with pins 15, and is swingable upwardly in the direction indicated by arrow a to a near vertical position such that the shaft or rotatable part or member 11 is exposed.

Mounted on the front of the cover 14 is a latch member 16, having a bifurcated vertical plate 17, formed with terminal claw members 18. The claw members 18 embrace a lock mechanism generally designated L supported on the wall 12 for movement in toward, and out away from, the rotatable member or shaft 11 in a manner which presently will be described. The lock mechanism L includes an outer casing 19 having a bore 20 for an internal slide or plunger 21 which is adapted to extend through a rectangular opening 22 provided in the wall 12 which prevents rotation of the slide 21.

At the inner end of the slide or plunger 21, a pin 23 pivotally mounts a probe 24, which, as FIGS. 5 and 6 indicate, can be moved into engagement with the rotatable part or shaft 11. As will later develop, when the part 11 is rotating in the direction 11, the probe 24 is pivoted to the position in which it is shown in FIG. 6 by the rotating shaft. A spring 25 is provided in the bore 20, and a spring 26 is likewise provided in a counterbore 27 at the inner end of casing 19, for purposes which will later become more apparent.

Also provided in the casing 19 to communicate with the bore 20, is a bayonet slot 28 having a lateral leg portion 28a and an axially extending leg portion 28b. A pin 29, fixed to the plunger 21, is received in the bayonet slot 28 and when the locked device is in the rest position, will be disposed in the axially extending leg portion 28b as shown in FIG. 4.

Also provided on the casing 19 are a pair of diametrically opposite flats or grooves 30 (see FIG. 3) which, when the casing is in the rotary postion shown in FIGS. 24, for instance, are angularly removed from the opening 31 between claws l8. Handlebars 32, provided on the casing 19, facilitate 90 rotation of the casing 19, which is possible only when the pin 29 is disposed in the lateralslot portion 28a as illustrated in FIG. 5, to line up the flats 30 with the claw mouth 31. When the casing 19 is rotated to this position, the latch 17 can be raised upwardly past the casing 19 in raised upwardly past the casing 19 in the direction a, to swing the cover upwardly about pivot pin 15.

THE OPERATION FIGS. 3 and 4 show the lock mechanism in an at rest" or normal position in which the probe 24 is disposed a distance c from the rotor 11. In this position of the locked parts, the spring 26 forces the casing 19 outwardly to the position indicated, and the spring 25 is exerting pressure on the slide 21. The flats 30 are disposed axially outwardly of the opening 31, and the casing 19, with the pins 29 in the axial portion 28b of slot 28, is angularly displaced 90 from a position in which the mechanism could be unlocked. In the position of the parts shown in FIG. 4, whether the rotor 11 is rotating or not, the latch plate 17 clearly cannot be lifted upwardly past the claws 18 (see FIG. 2).

If the operator now wishes to lift the cover 14, and presses inwardly on casing 19 to cause the probe 24 to engage a non-rotating rotor 11, and the spring 26 to be compressed, the pin 29 is forced upwardly in the axial of slot 28 to the position shown in FIG. 5. This occurs, if the rotor 11 is stationary and the probe 24 remains in axial alignment with the slide 21. In this position of the parts,'the spring 25 is, in fact, exerting a pressure on slide 21 urging it into engagement with the rotor 11. With the pin 29 in the position shown in FIG. 5, clearly, the handlebars 32 can be grasped and the casing 19 can be rotated 90 to bring the flats 30 to the position illustrated in FIG. in alignment with the opening 31 between claws 18. ln this position of the parts, the flats 30 line up with the opening 31 and the latch 17 can be lifted upwardly in the direction a to swing cover 14 upwardly.

If, however, the rotor 11 is rotating, as for instance in the direction b, the probe 24 is pivoted to the cocked or axially collapsed position in which it is shown in FIG. 6 and the pin 29 remains in the axial portion 28b of the bayonet slot 28 and prevents any unlocking rotation of the casing 19. If the operator then releases the casing 19, the spring 26 will return it to the position in which it is shown in FIGS. 3 and 4. A torsion spring 33 can be connected between the pin 23 and probe 24 to positively assure movement of the probe 24 back to the position in which it is shown in FIGS. 3 and 4. If the lock mechanism is used in vertical position, rather than a horizontally disposed position as illustrated, the forces of gravity will, of course, take care of moving the probe 24 back to the axially aligned position.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. A machine comprising: a framework, a drivable part, such as a centrifugal rotor, movably mounted on said framework; a releasable guard for the part; a latch part mounted on one of said framework and said guard; a rotatable lock member having a cylindrical bore supported for rotary movements about the axis of said bore between a position in which it coacts with said latch part to fix said guard in a position in which it cannot be released and a position in which said guard can be released; and motion sensing element means slidably received in said rotatable lock member for engaging said drivable part and controlling whether said lock member can be rotated between said positions.

2. The combination of claim 1 wherein said rotation sensing element means comprises a probe pivotally supported on said lock member to extend therefrom so that engagement with a drivable part pivots it from a normal position of extension to an axially collapsed position.

3. A machine comprising: a framework; a drivablev part, such as a rotatable, centrifugal rotor, movable on said framwork in an endless path; a releasable guard for the part; a latch part mounted on one of said framework and said guard; a lock member supported for rotary movements about an axis between a position in which it coacts with said latch part to fix said guard in a position in which it cannot be released and a position in which said guard can be released; and motion sensing clement means on said lock member for engaging said drivable part and controlling whether said lock member can be rotated between said positions, said lock member being mounted for axial movement to move said sensing element means into and out of engagement with said rotatable part; and mechanism for permitting or preventing rotation of said lock member depending on the axial position of said lock member; said sensing element means comprising a probe part mounted on said lock member to engage said rotatable part and prevent further axial movement of said sensing element means toward said rotatable part when the rotatable part is stationary while permitting axial movement of said lock member relative thereto to an axially inner position in which it can be rotated to a guard releasing position, said probe part being displaceable to a position permitting further axial movement of said sensing element means and said lock member toward said rotatable part when the rotatable part is rotating so that relative movement of said sensing element means and said lock member is not effected and said lock member cannot be rotated to said guard releasing position.

4. The combination defined in claim 3 in which said mechanism for permitting or preventing rotation of said lock member comprises a bayonet slot in said lock member and a pin controlled at least in part by the position of said probe extending into said slot and preventing rotation of said lock member when positioned in one portion of said slot.

5. The combination defined in claim 4 in which said lock member comprises a casing mounted for axial movement and having said bore with a slide movable axially therein; said bayonet slot comprising a lateral leg portion and an axial leg portion in said casing; and said pin extending from said slide into said slot.

6. The combination defined in claim 5 in which a spring positioned in the bore normally maintains said pin in the axial leg portion of the slot in a position preventing rotation of the casing.

7. The combination defined in claim 6 in which said casing is mounted on the framework of the machine which has an opening communicating with said bore and slidably, but non-rotatably, passing said slide; and a spring between said framework and lock casing normally holding said casing in a position in which the probe is removed from the rotatable member.

8. The combination defined in claim 7 in which said probe part is normally maintained by said latter spring at a spaced distance from the rotatable part equal to the length of the axial portion of the slot.

9. A machine including: a rotatable part; a frame supporting said part for rotation; a cover for said rotatable part; a lock for said cover having probe means, connected thereto for movement between a position engaging said part and a position removed from said part, for conditioning the lock for unlocking movement when engaged with the rotatable part when the part is at rest, said probe means being displaceable to a displaced position preventing unlocking of the cover when engaged with the part when the part is rotating, and means normally urging said lock and said probe means to positions removed from the rotatable part.

10. The combination defined in claim 9 wherein mechanism prevents movement of the lock to unlock the cover when the lock and means are in said removed position.

11. A machine including: a rotatable part; a frame supporting said part for rotation; a cover for said part; a lock for said cover having probe means connected thereto, movable between a part engaging position and a removed position for conditioning the lock for unlocking movement when engaged with the rotatable part when the part is at rest, said probe being movable to a displaced position preventing unlocking of the cover when engaged with the part when the part is rotating; said lock including a casing mounted for rotation and an axially movable slide therein, to the inner end of which said probe is connected, latch mechanism is connected between said slide and easing which in one position permits rotation of said casing, and in another prevents rotation thereof; and spring means maintain ing said latch mechanism in a position to prevent casing rotation when said probe is moved to a displaced position.

12. The combination defined in claim 11 in which said spring means comprises a spring between said casing and slide and a spring between said frame and casing.

13. A machine comprising: a driveable member, such as a centrifugal contactor shaft; a guard for said drive able member movable between a guard position adjacent said driveable member and a removed position; an enableable and disableable lock having a probe portion which is mounted for movement to and from a position of engagement with said driveable member; and means operated under the control of said probe portion for enabling or disabling said lock dependent on whether the driveable member is moving or stationary when engaged by the probe portion; said lock being mounted on the frame of the machine for movement toward and away from the driveable member; said guard including a part embracing a portion of the lock part to normally prevent movement of the guard to said removed position; said lock having a portion of decreased girth at a spaced distance from said lock part portion which is normally embraced which enables release of said cover when the probe portion is pressed into engagement with the rotatable member at a time when the latter is at rest.

14. The combination defined in claim 13 in which said portion of decreased girth comprises cutaway side portions of said lock which must be rotated to permit release of said guard; and said mechanism operated under control of said probe portion prevents or, en-

ables rotation of said lock.

Claims

3. A machine comprising: a framework; a drivable part, such as a rotatable, centrifugal rotor, movable on said framwork in an endless path; a releasable guard for the part; a latch part mounted on one of said framework and said guard; a lock member supported for rotary movements about an axis between a position in which it coacts with said latch part to fix said guard in a position in which it cannot be released and a position in which said guard can be released; and motion sensing element means on said lock member for engaging said drivable part and controlling whether said lock member can be rotated between said positions, said lock member being mounted for axial movement to move said sensing element means into and out of engagement with said rotatable part; and mechanism for permitting or preventing rotation of said lock member depending on the axial position of said lock membeR; said sensing element means comprising a probe part mounted on said lock member to engage said rotatable part and prevent further axial movement of said sensing element means toward said rotatable part when the rotatable part is stationary while permitting axial movement of said lock member relative thereto to an axially inner position in which it can be rotated to a guard releasing position, said probe part being displaceable to a position permitting further axial movement of said sensing element means and said lock member toward said rotatable part when the rotatable part is rotating so that relative movement of said sensing element means and said lock member is not effected and said lock member cannot be rotated to said guard releasing position.

11. A machine including: a rotatable part; a frame supporting said part for rotation; a cover for said part; a lock for said cover having probe means connected thereto, movable between a part engaging position and a removed position for conditioning the lock for unlocking movement when engaged with the rotatable part when the part is at rest, said probe being movable to a displaced position preventing unlocking of the cover when engaged with the part when the part is rotating; said lock including a casing mounted for rotation and an axially movable slide therein, to the inner end of which said probe is connected; latch mechanism is connected between said slide and casing which in one position permits rotation of said casing, and in another prevents rotation thereof; and spring means maintaining said latch mechanism in a position to prevent casing rotation when said probe is moved to a displaced position.

13. A machine comprising: a driveable member, such as a centrifugal contactor shaft; a guard for said driveable member movable between a guard position adjacent said driveable member and a removed position; an enableable and disableable lock having a probe portion which is mounted for movement to and from a position of engagement with said driveable member; and means operated under the control of said probe portion for enabling or disabling said lock dependent on whether the driveable member is moving or stationary when engaged by the probe portion; said lock being mounted on the frame of the machine for movement toward and away from the driveable member; said guard including a part embracing a portion of the lock part to normally prevent movement of the guard to said removed position; said lock having a portion of decreased girth at a spaced distance from said lock part portion which is normally embraced which enables release of said cover when the probe portion is pressed into engagement with the rotatable member at a time when the latter is at rest.

14. The combination defined in claim 13 in which said portion of decreased girth comprises cutaway side portions of said lock which must be rotated to permit release of said guard; and said mechanism operated under control of said probe portion prevents or, enables rotation of said lock.