Latching Mechanism

Abstract

A latching mechanism is provided which, for example, may be used to mount a cover over the rotor head of a microhematocrit-type centrifuge, and which permits the cover conveniently to be placed and latched onto the head, and just as conveniently to be unlatched and removed. The centrifuge rotor head, for example, may be of the type which supports a plurality of capillary tubes in general radial positions, the tubes containing solutions to be subjected to centrifugal separation of their constituents, and the cover serves to hold the tubes in place in radial slots on the base.

Description

BACKGROUND OF THE INVENTION

Microhematocrit centrifuge heads of the type with which the present invention is applicable are generally known. Such heads, for example, have a disclike shape and comprise a base in which the capillary tubes are positioned in radial grooves, and a cover which is attached to the base to hold the tubes in place. When the centrifuge is used for medical purposes. the capillary tubes may be filled with whole blood samples, and the head is rotated by the centrifuge about a central axis. The resulting centrifuge action serves to separate out the red cells of each sample to determine the blood characteristics, so that anemic and other conditions of various patients may be indicated.

In the past it was usual to attach the aforesaid cover to the base by means of a central-threaded bushing on the base which extended up through a central hole in the cover, and by means of an external nut which was threaded down onto the bushing.

The cover in the mechanism to be described, however, is held in place on the base of the rotor head by a simple latch. The improved construction of the combination of the present invention permits rapid loading and unloading of the head, since it is a simple matter to place the capillary tubes in their respective radial grooves, and then to press the cover down in place; and since it is an equally simple matter to remove the head by a simple lifting action, and subsequently to remove the capillary tubes.

Another advantage is that the latch mechanism may be operated by one hand, which is convenient when many capillary tubes are to be loaded into the head, or removed from the head, and since the operation can be carried out in a simple sequential manner. The latch mechanism to be described is long-wearing, and there are no threads to be stripped, as is the tendency in the prior art structures.

The centrifuge head to be described may be fabricated from appropriate material such as aluminum or titanium sheeting which is formed into shape, so as to provide a relatively inexpensive component. This is opposed to the prior art expensive approach which usually consisted of machining the parts from solid blocks of metal, such as aluminum alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective representation of a typical microhematocrit centrifuge which may be constructed to incorporate the head of the present invention;

FIG. 2 is a perspective view of the head cover;

FIG. 3 is a top perspective view of the base component of the head;

FIG. 4 is a side section of the overall head assembly; whereas

FIG. 5 is a side section of the improved latch mechanism which is used in the combination to attach the cover to the base.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

The centrifuge unit shown in FIG. 1 is designated generally as 10, and it may be of the type presently manufactured by the Phillips-Drucker Company of Astoria, Oregon, and designated by them as their L-411 p/d microhematocrit centrifuge. The centrifuge actually includes a guard 12 which is mounted on a housing 14. The guard 12 is bowl-shaped. The housing 14 is supported, for example, on rubber pedestals 16.

An appropriate electric motor is mounted within the housing 14 and is controlled, for example, by a timer control 18 mounted on the side of the unit. When the motor is energized, a centrifuge rotor head 20 within the guard 12 is rotated about its center to provide the desired centrifuge action. The unit 10 may be of drawn steel construction, and may be finished, for example, in baked colored enamel.

A lid 22 is hinged to the back of the bowl-shaped guard 12, and may be closed and latched when the centrifuge is operating. The rotor head 20, as shown in FIGS. 2 and 3 is made up of a disc-shaped base 26 having a dishlike configuration, and also of a cover 28 which may be removably placed over the base before the centrifuge is to be operated. As mentioned above, the base 26 includes a central post 32 having a bushing 51 welded thereto. The base 26 is attached to the bushing 51 by means, for example, of screws, such as the screw 53, or by other appropriate means. A pan member 50 fits around the central post, and it is shaped to define a series of radial grooves for supporting capillary tubes, for example, which are to undergo test. The cover 28 has a central bushing 34 which receives the post 32 in a telescopic coaxial relationship, when the cover is placed over the base.

In accordance with the concepts of the present invention, as will be described, the cover may conveniently be mounted on the base by a simple latching action, and by the latch shown in FIGS. 4 and 5. As mentioned above, the sectional view of FIG. 4 is taken through the complete head combination and includes the base 26 and the cover 28. The bushing 34 of the cover is also shown in FIG. 4, as is the post 32 of the base. The post 32 is actually tubular in form, so as to permit the drive shaft 66 (FIG. 5) of the drive motor to be received within the post 32 so as to cause rotational motion to be imparted to the head assembly.

As shown in FIG. 4, an inner pan assembly 50 is provided in the base 26, and which is corrugated, for example, so as to provide the radial grooves shown, for example, in FIG. 3. As mentioned above, the base 26, the pan 50 and the cover 28 all may be formed of a suitable material, such as aluminum, so that a light and easy to fabricate head is provided on a relatively inexpensive basis.

In each case, the bushing 34 has a plurality of openings formed in it, and balls 52 (FIG. 5) are positioned in the openings. When the cover 28 is latched down on the base 26, the balls 52 (FIG. 5) are received in a peripheral groove in the post 32, and are held in place by a retainer ring 56 which is welded, or otherwise attached to the lower rim of a tubular housing 58. The tubular housing 58 has a peripheral flange 58a at its upper end. A coil spring 60 is mounted around the bushing 34 between the ring 56 at one end and the lower rim of the skirt portion of a cap 62 at the other. The ring 56 has an inner peripheral groove, as shown.

So long as the latch assembly is in the position shown in FIG. 5, the cover 28 is firmly held in a latched position on the base 26, with the balls 52 being retained by the ring 56 in firm engagement with the wall of the peripheral groove in the post 32. To unlatch the assembly, it is merely necessary to pull the snapring housing 58 upwardly, by, for example, placing the thumb against the upper end of the bushing 34 and wrapping two fingers under the flange 58a. The housing 58 may now be pulled upwardly with respect to the bushing 34 until its groove is aligned with the openings in the bushing 34 so as to relieve the balls 52. The balls are then free to move out of the peripheral groove in the post 32 permitting the cover assembly as a whole to be moved up and off the assembly.

To replace the cover, the converse operations are carried out, with the housing 58 initially being held between the thumb and fingers of one hand against the tension of the spring 60, so as to align the peripheral groove of the ring 56 with the openings in the bushing 34 and to permit the bushing to be freely slipped down over the post 32. Then, when the balls engage the peripheral ring in the post the latch is released, and the spring 60 moves the ring 56 to a misaligned position, so that it firmly holds the balls in place and the assembly in a latched condition. It is apparent, therefore, that the cover may be put in place or removed, by a simple one-handed latching action.

As shown in FIG. 5, a counterbore is provided at the upper end of the tubular post 32, to receive the head of a thumbscrew 64. The thumbscrew is threaded into the end of the drive shaft 66 of the motor, so as to permit the head to be easily installed on the motor shaft, and just as easily removed from the guard 12 of FIG. 1.

The cap 62 is welded or otherwise attached to the bushing. The cap 62 provides a retainer for the spring 60, as mentioned above, and it also provides a convenient surface against which the thumb of the operator may be pressed, as he is drawing the flange 58a and the retainer 58 up to its unlatched position.

An improved head assembly is provided, by which the cover may conveniently be placed over the base, or removed, by a one-handed simple latching operation. When the cover is in place, it is held firmly and securely by the latch without any tendency for it to become loose. The latch mechanism itself is eminently simple, and may be constructed at a relatively low price.

While a particular embodiment of the invention has been shown and described, modifications may be made, and it is intended in the following claims to cover all such modifications which fall within the spirit and scope of the invention.

Claims

What is claimed is:

1. A latching mechanism for latching a cover over a base including a post having a peripheral groove therein intermediate its ends; a base secured to said post; a bushing member positioned to receive the aforesaid post in a telescoping coaxial relationship, said bushing member having at least one opening coaxial positioned in radial alignment with said peripheral groove when the aforesaid latching mechanism is in a closed and latch position; locking means positioned in said opening and engaging the side of said post when said post is in position in said bushing member; a cover for said base secured to said bushing member; and an annular retainer surrounding said bushing member and movable axially with respect thereto, said retainer having a peripheral groove in the inner surface thereof which when axially aligned with said opening frees said locking means from the aforesaid peripheral groove in said post and permits axial movement between said bushing member and said post, and said retainer locking said locking means in said peripheral groove in said post when said groove in said retainer is axially misaligned with said opening so as to prevent relative axial movement between said bushing member and said post.

2. The latching mechanism defined in claim 1, in which said locking means comprises at least one ball.

3. The combination defined in claim 1, and which includes resilient means for axially biasing said retainer to a fixed position relative to said bushing member in which said groove in said retainer is axially misaligned with said opening in said bushing member.

4. The combination defined in claim 3, and which includes means affixed to said retainer for axially moving said retainer against the bias of said resilient means to a second position relative to said bushing member in which said grooves in said retainer is axially aligned with said opening in said bushing member.

5. The combination defined in claim 1, in which said base and said cover each has a disclike configuration, and said post and bushing member each is centrally located with respect to said base and said cover.

6. The combination defined in claim 4, in which said resilient means comprises a coil spring mounted coaxially around said bushing member and having one end engaging an end of said retainer.

7. The combination defined in claim 6, and which includes a cap mounted on said bushing member and having a skirt portion with a rim engaging the other end of said coil spring.