GB2114250A - Household centrifuge with brake mechanism coacting with a safety locking device - Google Patents

Abstract

The present invention relates to a safety locking device for a household centrifuge coacting with a brake mechanism. The locking device comprises an actuator rod (4) provided with means to activate an electrical switch (8) which may control the centrifuge. At one end of the actuator rod, a connector means, preferably a bowden cable (5), connects the rod to the brake mechanism. The brake mechanism comprises a band-brake (2) and a pair of rotatable two-armed rockers (1, 6) which move under the action of the braking reaction and prevent further movement of the actuating rod (4) until braking is completed. At the other end of the actuator rod (4), a locking means (14, 18d, 19, 21 - Fig. 4) secures a cover (7) until travel of the actuator rod is completed. <IMAGE>

Description

SPECIFICATION Household centrifuge with brake mechanism coacting with locking device This invention relates to a locking device for a household centrifuge coacting with a brake mechanism.

A household centrifuge, such as found in a clothes drier, generally has a motor with a vertical shaft, a precipitator drum mounted on the motor shaft, a housing and cover for closing the housing on the top. The precipitator drum performs high speed rotary motion, consequently it is advisable, if not essential, to prevent accidental or deliberate access to the drum during rotation. Other household centrifuges are known with a horizontal shaft, and a precipitator drum mounted on said shaft.

Several solutions have been proposed to meet above requirements. There is known for instance a solution, wherein the electric switch and brake actuating lever, during the rotary motion of the precipitator drum, are arranged above the upwards opening cover, thereby preventing its opening.

Upon disconnection and braking, this lever is turned above the cover and the braking takes place during the time of turning. However, the cover can be opened while the drum is still in rotary motion, allowing the possibility of an accident. A further shortcoming of this solution is that the braking force has to be applied by hand.

Adequate safety precautions are offered by those solutions, where the cover is locked by a brake mechanism actuated with separate elements, which prevent opening of the cover. The common shortcoming of these solutions is the complicated construction.

Furthermore, a solution is described in the DE-OS 2 538 698, where the locking is ensured by movement brought about by a turning of the generally stationary part of the flexibly suspended motor during braking. This solution is a complicated construction and, apart from the mechanism actuating the brake and switch, additional structural elements are necessary for transmitting the movement of the motor body.

According to the DE-OS 2 171 and 2502390 the brake mechanism is fixed to a mobile supporting structure and movement of this supporting structure during braking ensures the locking of the cover through a Bowden cable or other similar means.

However, the mechanism ensuring the locking is complicated even in this solution, since the control of the locking devices is ensured through a separate Bowden cable.

The invention is aimed at the elimination of above short-comings, that is, at the realization of such a brake mechanism and locking device for a household centrifuge, which has a relatively simple construction and ensures the safe locking of the cover while allowing easy handling at the same time.

The invention is based on the recognition that the problem can be solved if disengagement of the centrifuge, actuation of the brake, locking of the cover, releasing the lock and opening of the cover are carried out be a single actuating element.

According to the present invention there is provided a locking device for a household centrifuge coating with a brake mechanism wherein the locking device comprises an actuator rod displaceable in a longitudinal direction and provided with means to actuate an electrical switch and provided at one end with a connecting means connecting with a brake mechanism, and the same rod having at its other end locking means to prevent the cover of the centrifuge being fully opened, the locking means comprising a lock bolt releasably securing a lock pin fixedly attached to the cover of the centrifuge, the lock pin having a first and a second engagement means separately and releasably engageable by the lock bolt such that the lock pin may be held by at either engagement means, the arrangement being such that when the first engagement means is engaged by the lock bolt, the actuating rod reversably actuates the electrical switch and when the first engagement means is released from said engagement the electrical switch is deactuated by the actuating rod and the second engagement means is engaged until the longitudinal travel of the actuating rod is completed, and a brake mechanism preventing the completion of the longitudinal travel of a actuating rod until the rotation of the centrifuge drum has ceased.

Conveniently the brake mechanism comprises a brake disk mounted fixedly on a motor shaft of the centrifuge and a band-brake actuated by the connecting means, one end of the band-brake being fixed to a first arm of a first two-armed rocker lever arranged on a motor shield and rotatable aboutthe motor shaft axis, the other end of the band-brake being attached to a first arm of a second two armed rocker lever mounted rotatably on the second arm of the first two-armed rocker, the second arm of the second two-armed rocker lever being attached to the connector means and the first two-armed rocker lever maintained in position by a draw spring, the arrangement being such that when a force in the connecting means causes the band-brake to impinge on the brake disk, the reaction in the band-brake rotates the first two-armed rocker lever and the reaction is transmitted through the second twoarmed rocker lever to the connecting means where it opposes the force, preventing further movement of the actuating rod.

Preferably a latch block tiltable against a spring prevents the disengagement of the second engagement means until the longitudinal travel of the actuating rod is completed.

More preferably the latch block has an adjustable stop screw.

In an embodiment the connector means comprises a Bowden cable and a spring means for tensioning said cable.

In an embodiment the first engagement means is disengaged by depressing a control button.

The invention will be further described with reference to the accompanying diagrams in which: Figure 1 shows in the upper part of the diagram, a vertical section of a centrifuge according to the invention, while the lower part shows the bottom view of the motor space of the centrifuge, Figure 2 shows in detail of the solution according to Figure 1, shown in a larger scale, Figure 3,: main elements of the detail shown in Figure 2, Figure 4.: locking device according to Figure 2, in another operating position, Figure 5.: sectional view of the locking device according to the invention by way of another example.

The centrifuge in Figure 1 is in the operating position. The brake mechanism according to the invention has a band-brake 2 mounted on a first rocker lever 1, actuated through an actuating rod 4 with a bowden cable 5 and a second rocker lever 6.

The second rocker lever 6 is formed as a two-armed lever rotatably fixed on the first rocker lever 1. The cover 7 of the centrifuge is in a closed position, the electric switch 8 is engaged, the motor of the centrifuge and the brake disc 9 fixed on the motor shaft 11 can freely turn. In this position the Bowden cable 5 is released, a draw spring 10 pulls the first rocker lever 1, rotatably mounted around the motor shaft 11, to a stop 1 2a formed on the motor shield, at the same time a compression spring 25 keeps the brake open by turning the brake lever 6 contrary to the direction of arrow "X", i.e. it keeps the band brake 2 away from the brake disc 9.

Upon pressing a button 13 of the locking device in direction "Y", the cover 7 of the centrifuge is lifted to a limited extent. In this case the braking spring 3 moves the actuating rod 4 into position "I" (as shown in Figure 2) and at the same time locks the brake by pulling the bowden cable 5. The frictional force arising produces the braking effect, while the braking reaction presses the first rocker lever 1 against the stop 12a. The reaction acting on the first rocker lever 1 counterbalances the force of the braking spring 3 through the second rocker lever 6, i.e. it prevents the further travel of the actuating rod 4 beyond position "I" as shown in Figure 2.

Upon completion of the braking said equilibrium and the braking spring 3 turn the rocker lever 1 in the direction of arrow "X" when the Bowden cable 5 is pulled, at the same time the actuating rod 4 is further lifted into position "II", as shown in Figure 2.

In position "II" following the braking, the actuating rod 4 opens the safety locking device of the locking device of the cover, and an opening spring 16 tips up the cover 7 of the centrifuge around a pin 15.

Figure 2 shows the locking device in the position when closing of cover 7 just begins. Figure 3 shows the structural solution of the two main parts of the locking device. Figure 4 shows the locked position of the locking device. The locking device shown by way of the first example has a lock pin 17 perpendicular to the cover 7 and a laminar lock bolt 18. The control button 13 on the side of the centrifuge is fixed to the lock bolt 18. A latch block 14 supported by a spring 19 is also part of the locking device (Figures 2 and 4).

The control button 13 can be pressed against a compression spring 20. An adjustable stop screw 21 is fitted into a threaded hole of the latch block 14. In the illustrated embodiment the latch block 14 is tiltably arranged around a pin 22.

As best shown in Figure 3 projections 17b and 17C are formed on the lock pin 17, which can be engaged with flanges 18a and 18b of a rectangular hole 26 of the lock bolt 18 (figures 2-4). Furthermore, a hole 18C is formed on the lock bolt 18 for the stop screw 21, a flange 18b of which is connected to the free end of the latch block 14 (Figure 4.).

Upon closing the cover 7, a slanting surface 17a of the lock pin 17 presses the flange 18a of the lock bolt 18 and pulls the lock bolt 18 inward. At the same time the end part of the lock pin 17 presses the actuating rod 4 downwards. When cover 7 is completely closed, flange 18a of the lock bolt 18 engages with the first engagement means 17b of the lock pin 17. In this case the actuating rod 4 is pressed down completely (position "III"), the locking device is open, while the electric switch 8 is actuated i.e. the centrifuge is operative. Opening of the cover 7 in this position is prevented by engagement of the engagement means 17b of the lock pin 17, with the flange 18a of the lock bolt 18.

Upon completion of the centrifuging the brake mechanism and safety latch of the locking device are actuated by the push button 13. Namely upon pressing the button 13 (Figure 4) the flange 18b of the lock bolt 18 steps into the path of the second engagement means 17C of the lock pin 17, while the flange 18a disengages with the first engagement means 17b of the lock pin 17. Because of the engagement of the flange 18b and the second engagement means 17C the spring 16 can open the cover 7 only to a limited extent, and due to this engagement further deliberate opening of the cover 7 is not possible.

Furthermore, upon pressing the button 13 the flange 18d of the lock bolt 18 leaves the free end of the latch block 14, whereby the compression spring 19 presses down the latch block 14.

In this position the latch block 14 prevents the compression spring 20 from pushing back the lock bolt 18, i.e. engagement of the flange 18b of the lock bolt 18 and the second engagement means 17c of the lock pin 17 cannot be released in this position (figure 4). Following the upward movement of the lock pin 17, the actuating rod 4 is lifted (position "I"), while the Bowden cable 5 activates the brake.

Upon completion of the braking, the brake spring 3 lifts the actuating rod 4 further into the position "II", where the end part of the actuating rod 4 presses the stop screw 21 and thereby lifts the latch block 14 into the position marked with dashed line in Figure 4. In this position of the latch block 14, the compression spring 20 is able to press the button 13 outwards, when the flange 18b of the lock bolt 18 disengages with the second engagement means of the lock pin 17, as a result of which the spring 16 opens the cover 7. Thus in the locking device according to the invention the safety locking of the cover 7 is guaranteed by the fact, that prior to the disengagement of the flange 18a, that keeps the cover 7 locked, from the first engagement means 17b of the lock pin 17, the flange 18b that prevents the opening of the cover 7 engages the second engagement means 17c of the lock pin 17. For this purpose the distance b between the flanges 1 8b and 1 8a has to be selected shorter than the width a of the lock pin 17 (Figure 3).

The latch block 14 may be made for instance of plate spring, in which case the compression spring 18 can be dispensed with. The intermittent movement of the actuating rod 4 of the brake mechanism according to the invention can be used for the actuation of a locking device constructed differently.

Such embodiment is shown in Figure 5., where instead of a button a lever 23, tiltably arranged on the cover against a spring, is used for opening the locking device. Here, the locking device is shown in the operating position of the centrifuge. The centrifuge is swtiched on by pressing down the cover 7.

Following the centrifuging, the lever 23 is pressed down in direction "Z", when an extension 23a of the lever 23 moves the lock bolt 18 against the compression spring 20, whereby the brake spring 3 lifts the lock pin 17 and cover 7 into the position marked with dashed line, where the brake is actuated (the same way as desrbied in the first example). Upon such movement of the lock bolt 18 the plate spring 24 moves downwards and prevents the lock bolt 18 from being pushed back by the compression spring 20. In this case the second engagement means 17c of the lock pin 17 contacts the flange 18b of the lock bolt 18, upon which the cover does not open and cannot be opened either.

Upon completion of the braking, the braking reaction no longer acts against the brake spring 3 (through the brake lever and Bowden cable), thus the brake spring 3 lifts the actuating rod 4, whilst its end part lifts the plate spring 24 by pushing up to the stop screw 21. At this stage the compression spring 20 moves the lock bolt 18 upon which the cover 7 opens or becomes openable.

The correct operation of the brake mechanism ensuring locking of the cover according to the invention as shown by way of the examples depends, apart from the proportions according to Figure 4, on the correct selection of the spring forces and the proportions of the arms of the second rocker lever 6. The brake mechanism is to be constructed as to allow the free rotation of the first rocker lever 1 around the shaft 11 in relation to the motor shield 12.

It is advisable to select the arm of the second rocker lever 6 facing the bowden cable 5 to be longer than the arm facing the band brake 2. Such proportion of the arms and the use of a brake material with a high frictional coefficient ensures thatthe braking reaction is counterbalanced by the pulling force of the brake spring 3 through the Bowden cable 5, i.e. the actuating rod 4 completes its travel only upon cessation of centrifuge rotation.

It is advisable to select the draw spring 10 and compression spring 25 to be weaker than spring 3.

The purpose of the draw spring 10 is to prevent the brake mechanism from rattling during the operation of the centrifuge and to keep it in a fixed position.

The locking device can be adjusted with the stop screw 21 in a simple way during assembly and repair.

Use of the solution according to the invention makes and additional element and transmission of locking motion or motion releasing the locking unnecessary. The invention allows simple construction, since only the actuating rod 4 has to be passed through from the motor space into the water space, which by itself is able to actuate the locking, as well as the engagement or disengagement of the brake and motor. In addition to the above, the invention offers a significantly simpler and less expensive solution, than those known at present. A further advantage is that the handling of a centrifuge which embodies a locking device according to the invention, is extremely simple and safe. Upon pressing the single button 13 or lever 23, the disengagement, braking, locking and safe opening of the cover are fully automatic.

Various modifications may be made within the scope of the invention. For example, the precipitator drum and motor may be mounted in a horizontal plane, as in a hot air drier.

Claims (9)

1. A locking device for a household centrifuge coacting with a brake mechanism wherein the locking device comprises an actuator rod displaceable in a longitudinal direction and provided with means to actuate an electrical switch and provided at one end with a connecting means connecting with a brake mechanism, and the same rod having at its other end locking means to prevent the cover of the centrifuge being fully opened the locking means comprising a lock bolt releasably securing a lock pin fixedly attached to the cover of the centrifuge, the lock pin having a first and a second engagement means separately and releasably engageable by the lock bolt such that the lock pin may be held by either engagement means, the arrangement being such that when the first engagement means is engaged by the lock bolt, the actuating rod releasably actuates the electrical switch and when the first engagement means is released from said engagement the electrical switch is deactuated by the actuating rod and the second engagement means is engaged until the longitudinal travel of the actuating rod is completed, and a brake mechanism preventing the completion of the longitudinal travel of a actuating rod until the rotation of the centrifuge drum has ceased.

2. A locking device as claimed in claim 1, in which the brake mechanism comprises a brake disk mounted fixedly on a motor shaft of the centrifuge and a band-brake actuated by the connecting means, one end of the band-brake being fixed to a first arm of a first two-armed rocker lever arranged on a motor shield and rotatable about the motor shaft axis, the other end of the band-brake attached to a first arm of a second two armed rocker lever mounted rotatably on the second arm of the first two-armed rocker, the second arm of the second two-armed rocker lever being attached to the connector means and the first two-armed rocker lever maintained in position by a draw spring, the arrangement being such that when a force in the connecting means causes the band-brake to impinge on the brake disk the reaction in the band-brake rotates the first two-armed rocker lever and the reaction is transmitted through the second two armed rocker lever to the connecting means where it opposes the force, preventing further movement of the actuating rod.

3. A locking device as claimed in claims 1 or 2, in which a latch blocktiltable against a spring prevents the disengagement of the second engagement means until the longitudinal travel of the actuating rod is completed.

4. A locking device as claimed in claim 3, in which the latch block has an adjustable stop screw.

5. A locking device as claimed in any of the preceding claims, in which the connector means comprises a Bowden cable and a spring means for tensioning said cable.

6. A locking device as claimed in any of the preceding claims, in which the first engagement means is disengaged by depressing a control button.

7. A locking device, substantially as described hereinbefore with reference to figures 2, 3 and 4.

8. A locking device substantially as described hereinbefore with reference to figure 5.

9. A centrifuge substantially as described hereinbefore with reference to figure 1.