EP0470428B1 - Lid latch for laboratory centrifuges, rotating at medium or high speed - Google Patents

Abstract

A mechanism for locking a cover to a housing of medium and high speed laboratory centrifuges. The locking mechanism includes an axially moveable locking member which has at least one locking portion adapted to be moved in locking engagement with a locking hole of the cover. The axially moveable locking member is rotatably mounted in the housing and connected with a rotary drive. An advancing mechanism transforms the rotary movement of the locking member into an advancing movement thereof. Preferably said advancing mechanism includes a threaded portion provided on the locking member and in engagement with a projection provided on the housing. The locking member has a portion of reduced cross section which may pass through a slot into the locking hole when the cover is moved to its closed position.

Description

The invention relates to a lid lock for medium to high-speed laboratory centrifuges with a housing and lid, an axially movable bar, which has at least one latch engagement with a latch opening on the lid.

Such interlocks are known. They are made by relays. Such relays depend on the power supply. If the latter fails, the lock can open. When using a magnet, a locking position can be maintained even in the event of a power failure. However, it can be released if, in the event of damage, an impact or impact hits an element of the locking device. This is particularly serious when a relay working with magnetic force, in particular with spring support, is effective. Vibrations can then occur which arbitrarily permit opening.

A locking device according to DE-A-29 07 789 is known with a rotary bolt which can be actuated by a handle or a corresponding drive. It is for locking a plate, the passage of an axis pin through a special hole in the other element is provided, the axis pin having a head with a cross section which, when the axis pin is rotated, creates the engagement behind an abutment. A manual operation with a handle head is shown. In this known embodiment, the axis pin can only reach the area of the locking possibilities through slots in a certain orientation. However, this presupposes that the arbitrarily adjustable axis pin has been brought into a corresponding orientation when a lock is closed. Here, the locking is provided at right angles to a plate which is practically arranged as a lid. This known design is defective because strikes, vibrations or stops on cross pins can lead to the opening of the closure.

It must be taken into account here that the lid of centrifuges is under a spring preload which tends to open the lid when the lock is released. This is important because in the commercial use of laboratory centrifuges, a quick sequence of the respective function settings is important.

A locking with an electromagnet is known from FR-A-2 524 346. This clearly shows that in the event of a power failure, even if a spring force holds an electromagnet in its locking position, jumping off or returning could take place if part of the destroyed rotor hits this locking part.

From DE-A-37 27 168 radially arranged locking pins with a rotary drive are known, the rotation of which extends, for example, only over 30, but by means of linkages or engagement devices in this area already causes several radially outwardly directed bolts to be brought into their engagement position . This known embodiment has the advantage that, because of the radially symmetrical structure, locking is largely the same over the circumference.

Here it is not excluded that automatically working devices are used. However, it is essential for the known embodiment that a rotary drive that can only be used by a small angle has to be actuated in order to use bolts that can be moved outwards. However, this is disadvantageous because, in the event of such a joint actuation, in the event of the rotor bursting, parts which have blown off can strike a locking element in order to throw it out of the general position and thus open a lid of a centrifuge.

The invention is therefore based on the object to provide a lid lock for medium and high-speed centrifuges, which remains securely in its locked position even in the event of failures, be it due to the bursting of the centrifuge rotor or even in the event of a power failure to actuate the bolt the lock itself is exposed to shock or impact stresses, while at the same time creating a small-scale solution.

A so-called medium or high-speed centrifuge works in the range from 15,000 g to 50,000 g.

It may be known to move a bolt by means of a spindle by an electric motor. However, this would involve a displacement movement in which a bolt would only be axially displaced in its permanent orientation. Such a solution would be conceivable at best.

A latch opening on the lid can be designed in the manner of an eyelet, into which one simply pushes a pin. For this purpose, an electromagnat or a relay is known as the drive element. If, in the event of a power failure and in a dangerous state, the broken rotor strikes an element, the locking is released in such a known embodiment.

According to the task mentioned above, this should just be prevented.

This object is achieved in that the axially displaceable bolt is rotatably supported, is provided with a rotary drive and a feed arrangement which on the one hand has a part arranged in the centrifuge and on the other hand has a profile on the bolt which are in engagement with one another and one of which Parts has an oblique to the axial direction of the locking engagement surface, and that the at least one opening on the lid has an entry slot for the passage of a tapered locking portion, which is followed by a reinforced locking portion corresponding to the diameter of the opening with a small undersize. Prefers the axially displaceable bolt is rotatably mounted in the housing.

The rotatable mounting of the bolt in conjunction with a rotary drive provides a safe engagement situation with the smallest space requirement, because the axial movement of the bolt precludes misalignment with the at least one bolt opening on the cover.

Of course, more than one, in particular more than two, bolt interventions are particularly preferred. In this context, the solution with a rotary drive that works with high torque is particularly advantageous.

The claimed feed device is provided independently of the rotary drive, which should only introduce one movement. The feed is achieved in the simplest solution by the special design as a threaded section with a pitch in the axial direction. In the simplest case, it is a bayonet-like guide which, when actuated, produces a bolt engagement.

The axial movability of the bolt is important and the rotary drive for the lid lock is provided for this.

This feature is particularly important because two engagement elements interact in comparison with the different designs. It is preferred that two or more openings are arranged on the cover and locking sections on the bolt. This opens up all possibilities for multiplication. For the axially movable mounting of the bolt, however, an engagement element designed as a threaded section with a pitch in the axial direction is preferred.

In connection with a bayonet-like connection, it is also not excluded that a wall part defining an engagement element can be extended to such an extent that possible failures no longer have to be taken into account.

If, however, a threaded section has already been addressed, then a minimum version is that the threaded section extends by at least 25 ° in the circumferential direction of the rotatable latch.

Such a division is essential, especially if the wall part extending in the circumferential direction has only a protruding or retracting profile. A threaded section can advantageously have several gears.

Based on the fact that a large number of designs is conceivable in connection with the present solutions, the original and inventive step claimed for the embodiment described in the further claims is claimed because such designs are not obvious.

However, the threaded section located on the bolt, which is designed as a spindle, is particularly preferred. There is already a certain limitation in the threaded section according to the introductory remarks. According to the explanations above, the threaded section forms the basis for the normal drive.

When the lid is closed and the grub screw is lined up, i.e. a passage in the spindle, it is initially left open that the threaded section has a continuously identical pitch, in addition it is preferred that the threaded section has a different pitch over its length, by means of which the end axial movement of the bolt is carried out faster than the initial axial movement.

This is a particularly important embodiment. That being said, the particularly preferred embodiment is that the thread at the end which corresponds to the engagement position of the bolt has a substantially pitch-free course. The slope-free passage forms a particularly firm restraint with additional security in the event of an emergency and shock loads on the bolt.

In various embodiments, the invention is preferably based on the bolt itself being designed as a rod or linkage which is rotatably mounted and is displaceable in the axial direction. This rod has different lengths in different designs, in particular with different diameters.

In this design, an advantageous embodiment is that a reinforced locking section is designed conically in the feed direction for engagement in the opening. The outer walls of a centrifuge can be used to form a guide in order to ensure that the bolt can be axially displaced in connection with the rotary drive, in particular or without a geared motor, but to prevent rotation of the rotary drive, in particular the motor itself.

In a further advantageous embodiment, the gear motor providing the torque is designed with a high reduction ratio. This results in a high torque. If the bolt is connected to the rotary drive itself, there is also a connection in a countershaft gear coupling, which allows any step-up or step-down. It is important that the bolt is driven by rotation, it being reserved that the bolt is arranged in the axial extension of the shaft of the geared motor.

It is included here that a motor known above is firmly connected to the bolt and secured against rotation, but is movably guided in the housing in the axial direction of the bolt.

However, a configuration is also not ruled out, in which the motor is fixedly mounted and is connected to the bolt with a torque clutch which allows axial movement between the coupling halves.

In the preferred embodiment, the at least one opening on the lid is arranged on an extension extending from the lid, for which lateral guides are arranged in the centrifuge in the area of the latch in the engaged position. The section with the reduced cross section is held in the engaged position on the bolt as soon as it is unloaded.

Cylindrical guide sections are expediently provided on the rotatably mounted bolt which are guided in guide bushings on the housing. This is a simple design, which is also space-saving, especially since the same means or lateral guide stops can also be provided for the lugs arranged on the cover.

If guide sections of the cylindrical and rotatable bolt are addressed above, it is understood that for the purpose of a practical configuration, a guide section is formed by a spindle.

Included in this version, in which an axially movable bolt can be moved with drive means which have self-locking properties against loosening, that two limit switches are provided with an actuating stop on the bolt, the switches being arranged obliquely to the bolt axis and their opposite actuating elements in each case the bolt axis are arranged.

Such limit switches may be common, but their special arrangement is useful in terms of a small structure of the device. In this case, a trigger switch is also included, which is arranged in the housing and can be actuated by striking an attachment with an opening when the cover is closed.

Even if such configurations are safe in an emergency and possibly in the event of a power failure, one condition is that a cover lock should be able to be released by manual operation.

For this purpose, it is preferred that one end of the bolt is provided with an engagement profile, in particular a slot for a tool, and in the extension of the bolt, a wall opening is arranged in the housing of the centrifuge for introducing an actuating instrument, in particular a screwdriver.

If there is an engagement of this type in one embodiment at the free end of the rotatably mounted bolt, in particular at the end with the axial driving part, in particular a spindle with a different pitch over its length, a particularly preferred embodiment is that the engagement profiles on the Motor shaft of the bolt drive motor are arranged.

Fig. 1

eine perspektivische Ansicht einer Zentrifuge in formaler Ausführung mit eingezeichneten Funktionsteilen zur Erläuterung der weiteren Ausgestaltungen;

Fig. 2a 2b

eine Draufsicht in Teildarstellung mit der Riegel-Anordnung in gegenüber Fig. 1 vergrößertem Maßstab;

Fig. 3a 3b

eine im Maßstab der Fig. 2 entsprechende Seitenansicht einer solchen Ausgestaltung mit ausgebrochenen Teilen bzw. auch in Teildarstellung;

Fig. 4

eine Einzeldarstellung eines Ansatzes, wie er beispielsweise in den Figuren 2 und 3 verwendet wird, jedoch rechtwinklig zu seiner Fächenerstreckung gesehen;

Fig. 5

eine Teilansicht des Riegels mit dem Gewindeabschnitt in besonderer Ausgestaltung in Seitenansicht.

Fig. 2a und 2b sowie 3a und 3b

sind seitlich zueinander ergänzend zusammenzusetzen.

The invention is explained below using an exemplary embodiment which is shown in the drawing.
The drawing shows:

Fig. 1

a perspective view of a centrifuge in a formal design with drawn functional parts to explain the other configurations;

Fig. 2a 2b

a plan view in partial representation with the latch arrangement on an enlarged scale compared to Figure 1;

3a 3b

a side view corresponding to the scale of Figure 2 of such an embodiment with broken parts or in part.

Fig. 4

an individual representation of an approach, such as is used for example in Figures 2 and 3, but seen at right angles to its extent;

Fig. 5

a partial view of the bolt with the threaded portion in a special embodiment in side view.

2a and 2b and 3a and 3b

are to be put together to complement each other.

In all figures, the same parts are described with the same reference numerals.

1 shows a laboratory centrifuge 1 with a housing. This housing 2 has in its cover plate a hinge 3 for a hinged cover 4. This covers a space 5 with a special wall thickness as a burst protection. A rotor 6 for a laboratory centrifuge with all parts is stored within the space 5.

This rotor 6 is covered in the room 5 on the one hand by the wall parts and the floor of the room and on the other hand by the cover 4.

In the present case, it is important to lock the cover 4, even against the force of a spring 7, which is arranged in the interior of the space 5 and strives to open the cover. A corresponding spring can be arranged in the hinge 3.

It is essential that a cover lock 9 is provided at a distance from or opposite to the hinge 3, as will be described in more detail below.

The lid 4 can be seen from FIGS. 2 and 3. It can be seen that lugs 10, 11 directed downward are arranged on the cover. For the lugs 10, 11 on the cover 4, 2 guide openings 47, 48 are arranged in the housing, which in particular hold the area 2 of the opening 15 together, so that the lug cannot expand when the bolt engages and loads.

These lugs, which are attached to the cover by means of screws 12, 13, for example, have a web-like surface 14 in the side view according to FIG. 4, but a circular opening 15 at their lower end, which in turn is open or downward through a slot 16 is accessible.

These are the two elements 10, 11 which are arranged on the cover 4.

A latch 17 is guided within the housing of the laboratory centrifuge according to FIGS. 2 and 3. This bar is designed as a rod or rod. This bar 17 has different sections over its length. It is guided by means of cylindrical sections 18, 19 into cylindrical guide openings 20, 21 in components or guide bushes 22, 23 which are mounted in the housing of the laboratory centrifuge. The section 19 is, for example, a cylinder which is mounted in the guide opening 21 with a small undersize. The section 18 is correspondingly guided in the guide opening 20, so that the bolt 17 is movable as a rod in its axial direction. The section 18 is, however, designed in a special way with an engagement surface 24 which extends in the circumference and radial direction, into which a grub screw or projection 25 engages on the component 22, which is arranged in the housing, just like the other components 22, 23 which are practically guide blocks with the guide openings 20,21.

Such engagement forms a propelling element for the rod or linkage, which forms the bolt 17. Such a rod or linkage is on its section 18 opposite end connected by a clutch 26 to a gear motor 27 which has a reduction gear. Such a motor 27 is mounted in lateral guides 28, 29 in a rotationally fixed but axially displaceable manner.

In the advantageous embodiment shown, the output shaft 30 is in axial alignment with the bolt 17, which is designed as a rotatable rod.

In addition to the sections 19 and 20 which are arranged for guidance in the guide openings 20, 21 of the components 22, 23, this rod has the sections 31, 32 with a cross section which is so greatly reduced that this section passes through the slot 16 (FIG. 4) can engage in the opening 15 in the lugs 10, 11 on the lid.

In the position shown in FIG. 3, the cover 4 can be closed, the lugs 10, 11 engaging with their slots over the tapered sections 31, 32 of the bolt 17. At the same time, however, a switch 33 is actuated which immediately switches on the movement of the motor 27 to advance the bolt 17.

The propulsion results from the interaction of the projection 25 with the engagement surface 24. As a result, the cones 34, 35 occur on the bolt 17 or the rod in question in the opening 15 (FIG. 4) and, due to their taper, still perform certain alignment functions.

At the end of the cones 34, 35, cylindrical locking sections 36, 37 enter the openings 15 and thus hold the cover 4 in place. The cylindrical locking sections 36, 37 have a diameter which fits into the openings with very little play, one of which is designated by 15 in FIG.

The engagement surface 24 is designed in the form of a spindle 45, which thus also forms the section 18.

During this movement, the motor 27 can move axially in its mounting.

If such a motor 27 is axially fixed, an axially displaceable clutch is arranged at 26, which permits torque transmission even when the engagement changes axially.

A switch actuating means 38 is arranged on the bolt 17 or on such a rod as a thickening. It works depending on the setting of the linkage with one of the 39 or other 40 actuators of two limit switches 41, 42, which are arranged obliquely to the axis of the bolt 17 so that the actuators 39, 40 lie in the line of the bolt 17. As a result, the switch actuation means 38 can engage with one or the other actuation element 39, 40 for switching the motor 27. The distance between the actuators 39, 40 is such that a switch-off always takes place when either the tapered sections 31, 32 their area of the lugs 10, 11 or the locking sections 36, 37 are arranged in the openings of the lugs 10, 11 , such an opening being drawn at 15 in FIG. 4.

The engagement surface 24, which can also be designed with a fraction in the circumferential direction with a slight slope in the form of a bayonet lock, is shown in the drawing as a threaded section in the form of a spindle 45.

In FIG. 5 it can be seen that a spindle 51 has gear sections 52, 43 with a different pitch over its length, a substantially pitch-free gear 44 then being arranged at the end for secure locking. The passage sections 52, 43 form the engagement surface 46.

From Fig. 2 a it can be seen that at the end of the bolt 17 in this case a profile 49 is arranged for example as a slot in the end face of the spindle arranged there. In the axial direction of the bolt 17 there is then a wall opening 50 in the wall of the housing 2 of the laboratory centrifuge for carrying out a tool. This wall opening can be closed. They can be used to insert a hand tool for engaging the profiling 49 in order to carry out manual operation in the event of a power failure.

Claims (22)

1. A mechanism for locking a cover to a housing of a medium or high speed laboratory centrifuge, including a locking member having an axis and being axially moveable into locking engagement with at least one locking hole of the cover, characterized in that said locking member (17) is mounted in said housing (2) so as to be rotatable by a rotary drive (27) and includes an advancing mechanism comprising first means (25) fixed with respect to said housing (2) and second means (24) on said locking member (17), said first and second means being in engagement with each other and one of said first and second means comprising an engagement surface (24, 46) inclined with respect to the axis of said locking member (17), and in that said locking member (17) includes at least one portion (31; 32) of reduced cross-section and at least one adjacent locking portion (36; 37) of increased cross-section, said portion of reduced cross-section being adapted to move transversely through an entry slot (16) opening into said locking hole (15),and said locking portion (36; 37) of increased cross-section being adapted to be received in said locking hole (15) for locking engagement therewith.
2. The locking mechanism of claim 1, wherein said locking member (17) is adapted to be in locking engagement with said cover (4) at more than one, in particular more than two locations.
3. The locking mechanism of claim 1, wherein said engagement surface of said advancing mechanism comprises a threaded portion having an axial pitch.
4. The locking mechanism of claim 1, wherein said advancing mechanism comprises a bayonet type drive connection between said first and second means.
5. The locking mechanism of claim 2, wherein two more locking holes (15) are provided on the cover (4) and two or more locking portions (36, 37) are provided on the locking member (17).
6. The locking mechanism of claim 3, wherein said threaded portion extends for at least 30° in the circumferential direction of said rotatable locking member (17).
7. The locking mechanism of claim 3 wherein said threaded portion has a plurality of threads.
8. The locking mechanism of claim 7, wherein said threaded portion is provided on said locking member (17) and comprises a spindle (45, 51).
9. The locking mechanism of claim 8, wherein said spindle (45, 51) has portions of different pitches along its length.
10. The locking mechanism of claim 9, wherein said threaded portion has a thread (44) of zero pitch at one end to define to a locking position of the locking member (17).
11. The locking mechanism of claim 1, wherein the locking member (17) includes a tapered portion (34; 35) adjacent said locking portion (36; 37) so as to facilitate entry of said locking portion (36; 37) into said locking hole (15).
12. The locking mechanism of claim 1, wherein said rotary drive comprises a gear motor (27) providing a substantial speed reduction.
13. The locking mechanism of claim 12, wherein said locking member (17) is axially aligned with an output shaft of said gear motor (27).
14. The locking mechanism of claim 12, wherein said gear motor (27) is fixedly connected to said locking member (17) and is mounted in said housing (2) so as to be axially moveable with said locking member (17).
15. The locking mechanism of claim 12, wherein said gear motor (27) is stationary with respect to said housing (2) and is connected to said locking member (17) by a torque clutch (26) including a pair of clutch halves axially moveable with respect to each other.
16. The locking mechanism of claim 1, wherein said at least one locking hole (15) is provided on a lug (10, 11) extending from the cover (4), said casing (2) including lateral guides (47, 48) for receiving said lug (10; 11) when said locking member (17) is in locking engagement with the cover (4).
17. The locking mechanism of claim 1, wherein said locking member (17) includes cylindrical guide portions (18, 19) adapted to be guidingly received in guide sleeves (22, 23) provided on said housing (2).
18. The locking mechanism of claims 8 and 17, wherein one (18) of said guide portions comprises said spindle (45).
19. The locking mechanism of claim 1, wherein a pair of limit switches (41, 42) and a switch control member (38) are provided on said casing and said locking member (17), respectively, and said limit switches (41, 42) have axes inclined to the axis of the locking member (17) and include actuating members (39, 40) disposed in a plane intersecting the axis of the locking member.
20. The locking mechanism of claim 1 including a trip switch (33) provided in said housing (2) and adapted to be operated by a portion (11) of the cover (4) when the cover is moved to its closed position.
21. The locking mechanism of claim 1 including manual means for releasing the locking mechanism, said manual means comprising profiled means (49) on one end of the locking member (17) or on a shaft of said rotary drive of the locking member (17) , and a closeable access opening (50) in a wall of said housing (2) allowing to move a manual tool into engagement with said profiled means.
22. The locking mechanism of claim 21, wherein the profiled means (49) are provided on the shaft of the motor for the locking member.

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