WO2003061443A1

WO2003061443A1 - Improvements in toasters

Info

Publication number: WO2003061443A1
Application number: PCT/AU2003/000037
Authority: WO
Inventors: Anthony Charles Lawson
Original assignee: Anthony Charles Lawson
Priority date: 2002-01-18
Filing date: 2003-01-16
Publication date: 2003-07-31
Also published as: AUPS004102A0

Abstract

A toaster (10) of the 'pop-up' type having a body (11) in which there is located a carriage (20) which is moved downwardly to place the bread to be toasted adjacent the heatings elements, and upwardly to permit the toast to be removed from the toaster (10) characterised in that the upward movement of the carriage (20) is controlled to provide a smooth delivery of the toast. The control of the upward movement adjacent the upper part of the movement may be by a resilient device (21) which acts to cause the carriage to stop smoothly and in one form of the invention there is a flywheel (43) which is caused to rotate on movement of the carriage (20) to temper movement of the carriage (20). In another form of the invention, I provide a motor to lower the carriage (20) and when the carriage (20) rises there can either be a flywheel (43) associated therewith or the motor can provide a force to control the rate of movement.

Description

IMPROVEMENTS IN TOASTERS

Technical Area

This invention relates to improvements in toasters and, in particular to improvements in the delivery of the cooked toast from the toaster.

Background to the invention

Most electric toasters in use today are so-called 'pop-up' toasters in which the carriage control for the toast is a spring mechanism which when the bread to be toasted is to be lowered into the toaster, it is necessary to compress the mechanism. Means are provided to hold the bread in position until a time determined by an adjustable timer has expired. At this time, the mechanism is released and the spring mechanism will then raise the toast. Normally the movement of the carriage breaks the electrical connection to the heating elements or both functions can be operated by the same switch which causes the mechanism to be released and the power to the elements disconnected.

In this specification, the words 'bread' and 'toast' are used in a generic sense and can refer to any product which can be toasted in the toaster and the toast formed therefrom. For example toasters can be adapted to toast very light articles, such as croissants or fruit loaves to substantial articles, such as crumpets and these, for the specification will all be considered 'bread' and the completed product 'toast'.

The spring action has to be sufficient to raise the heaviest slices of toast which may be toasted, and often this spring action tends to be too forceful when light bread is toasted, particularly when only a single slice of such bread is cooked. Under these circumstances the toast can actually be ejected from the toaster. A further problem associated with such means of carriage control is that often small slices of toast, even at the uppermost position of the carriage mechanism, do not protrude from such toasters.

Outline of the Invention

It is the principal object of this invention to provide a toaster which has a mechanism such that the raising of the toast after cooking is controlled.

The toaster of the invention is of a 'pop-up' type having a carriage which is moved downwardly to place the bread to be toasted adjacent the heating elements, and upwardly to permit the toast to be removed from the toaster characterised in that the upward movement of the carriage is controlled to provide a smooth delivery of the toast.

In a preferred form of the invention, there is a rack and pinion associated with the carriage the pinion being associated with a flywheel so that as the rack and pinion move relative to each other, the flywheel is caused to rotate and the inertia of the flywheel ensures that the relative movement is controlled.

It is preferred that the rack is associated with the body of the toaster and the flywheel and pinion assembly is attached to the carriage so that any force endeavouring to move the carriage relative to the body will effect rotation of the flywheel and thus keep the motion controlled.

In a first form of the invention, when the carriage is lowered, it is lowered against a return spring and when it is being raised by the pressure applied by the spring, the movement is tempered by the inertia of the flywheel.

It is preferred that the downward movement of the carriage be effected by the person operating the toaster pressing down on a carriage handle but it is possible to provide a motor driven movement of the carriage. If the toaster is provided with a motorised carriage to lower the bread and raise the resulting toast which carriage control includes a motor which may be an induction motor, or direct current motor, a gearbox to provide the required speed of movement and a spring to return the carriage to its upper position.

For smoothness of operation it may be preferred to have a flywheel associated with the motor.

For further exemplification, we shall consider the invention as applied to a toaster and the toasting of bread or other farinaceous material and reference will be made to the accompanying drawings, in which:

Fig 1 is a perspective view of the toaster of the invention;

Fig 2 is an end view of the return spring, the rack pinion and flywheel which control the movement of the carriage, the carriage being in its uppermost position;

Fig 3 is a view similar to that of Fig 2 with the carriage in its lowermost position; and

Fig 4 is a side view similar to that of Fig 3 showing the relative positions of the various components.

The toaster 10 of the invention can be considered in general terms to be very similar to a standard 'pop-up' toaster.

In a conventional manner, it has a body 11 which may comprise or be attached to a frame, which body 11 may be of pressed metal or injected plastics material and which has located therein one, two or more toast receiving slots 12. The illustrated toaster is the most usual form having two slots and the remainder of the description will relate to such a form of toaster. Within the body 11 and on each side of toast receiving slots 12 there are radiant heating elements (not shown) which extend over the whole of the area in which bread is to be received for toasting. Generally, there is a single central element which lies between the toast receiving areas and two spaced outer elements. The formation of the central element may differ from the formation of the two outer elements. This is well known in the art as the elements are designed so as to, as far a possible toast both sides of the toast equally whilst, at the same time, when only a single slice of bread is being toasted, not to over-toast the side directed towards the centre element and the outer element outwardly thereof.

Within the spaces between the sets of elements there is a carriage assembly 20 which has a pair of components each of which is adapted to receive a slice of bread to be toasted and to hold this whilst it is lowered into the spaces between the elements, whilst it is being browned and then to deliver the toast after completion.

Normally the carriage assembly is lowered by a carriage handle 14 which extends outwardly of the casing through a slot 15 formed therein and is moved against a spring 21. When the carriage reaches the bottom of its movement, it is latched in position, as shown by a bar 22 associated with a solenoid and retained latched during the period in which the elements are operating and the toast browned or bread defrosted. On completion of the operation, the latch 22 is released as the solenoid is switched with the elements and the spring 21 draws the carriage assembly upwardly. The toasting position is shown in Fig 3.

In the toaster of the invention, we provide a rack and flywheel assembly 50 which controls the movement of the carriage assembly.

In a preferred form of the invention, the flywheel 43 is located on the carriage, at one end thereof adjacent the upper part of the carriage assembly. The flywheel may be mounted for rotation about a horizontal axis 45 on a plate 44 which can also carry the carriage handle 14, the lower connection point 46 for the return spring 21 and a solenoid bar 22 which acts to latch the assembly in its lowermost position. In a preferred form of the invention, the flywheel may be of a plastics or metallic material. Co-axial with the flywheel there is a pinion 41. The pinion can be integral with the flywheel or it can be attached thereto. In either case, it will be appreciated that it rotates with the flywheel.

Mounted on the toaster frame, there is a rack 40 which may preferably be of a plastics material and which has teeth which correspond to the teeth on the pinion. The rack can be connected vertically between the base of the frame to the upper end thereof and is located so that the teeth of the pinion 41 mesh with the teeth of the rack 40.

Associated with the flywheel is a runner 42 which is fixed relative to flywheel plate and spaced from the pinion a distance slightly greater than the thickness of the rack. This runner may be of a low friction plastics material having a curved surface directed towards the rack so that it does not act to unduly restrict the movement relative to the rack. Alternatively, it could comprise a roller or the like.

The arrangement is such that the rack does not have to be tightly and firmly located against the pinion but can be allowed to flex and the engagement of the rack and the pinion is assured by the relative positions of the pinion 41 and the runner 42. This is advantageous as, even though the rack is preferably of a plastics material which does not exhibit substantial length change through temperature, there can be substantial changes within the body of the toaster between cold to the temperature after a number of pieces of toast have been sequentially cooked.

If a metal rack is used, then there can be quite substantial changes in length and the arrangement is such that the rack is at all time maintained in contact with the pinion.

Connected between the frame, adjacent the top thereof, and the plate 44 to which the flywheel is attached is a return spring. The upper end of the spring passes through an aperture 47 associated with the toaster body and the lower end about a pin 46 attached to the plate 44. This spring must have the characteristics that when the carriage is in its upper position, as shown in Fig 2, the spring is fully retracted, and when the spring is extended, when the carriage is in its lowest position, as shown in Fig 3, then the pressure exerted by the spring is optimal.

The carriage handle 14, by means of which it is moved to its lowered position, is, as mentioned above mounted on the same plate 44 as the flywheel and preferably a distance such that it can act as part of a brake mechanism used when the carriage reaches the top of its movement.

In a preferred form, there can be a N-shaped spring 51 extending downwardly from the top of the frame, one arm of which extends over the path of the surface of the flywheel directed theretowards and the other arm across the plane of the carriage handle. The arrangement is such that as the carriage moves towards its uppermost position, as shown in Fig 2, the spring will contact both the flywheel 43 and the handle 14, or some other protrusion that is attached to the carriage, be deformed somewhat and act as a brake on the movement of the flywheel and thus the carriage assembly. This spring will be shaped and positioned so as to exert an increasing braking force on the flywheel, as it nears the top of its travel, thus bringing the carriage to a gentle, rather than to an abrupt stop.

When the carriage has come to rest, the braking effect of the N-shaped spring will hold the flywheel static, thus preventing the carriage from rebounding off its upper stop and coming to rest at a lower level, causing the user difficulty in retrieving the toast.

As mentioned previously there can also be a latch 22 attached to the plate 44 which latch engages with a solenoid which acts to hold the carriage assembly down whilst the toast is cooking but which is released at the end of the cooking cycle, which is normally time based but which could be controlled by the toast reaching a predetermined colour. In the light of the foregoing, I shall describe the operation of the toaster.

The power to the toaster is turned on and, assuming a conventional arrangement, one or two slices of bread are placed through the slots 12 in the toaster body onto the carriage and the user causes the carriage to move downwardly by pressing on the carriage handle 14.

The downward movement will be resisted somewhat as the downward movement causes the pinion to move over the rack and this, in turn causes the flywheel to rotate so that there is inertia from this rotation and secondly by the extension of the return spring. The resistance is not excessive and the carriage will be moved to it lowermost position at which time the carriage will be locked, the latch 22 locking behind a solenoid latch.

The locking, or a function actuated at the same time as the locking applies power to the elements through a timing circuit the setting of which is controlled by the operator by a dial 16 or slide controller external to the toaster body and which may be a rheostat or variable capacitance in a timing circuit.

After this circuit has timed out, the power to the elements is cut-off and the solenoid released to free the latch 22 and thus the carriage.

The restoring force on the spring then endeavours to raise the carriage but as it starts to rise the pinion 41 moves along the rack 40, the flywheel commences to rotate and the inertia of the flywheel acts to temper the movement of the carriage which thus rises smoothly.

As it comes close to the top of its movement, the N-spring brake 51 passes between the carriage handle and the flywheel thus causing the rotation of the flywheel to be gradually slowed and then stopped, all movement ceasing as the carriage rises to the top of its movement. It will be seen that this embodiment of the invention can be engineered into a standard

'pop-up' toaster for very little additional cost and the end result is a toaster which operates very much more smoothly than a conventional toaster and which gives the feeling of being a more expensive, fully engineered product relative to a conventional toaster.

Rather than use a rack and pinion arrangement, this may be replaced by a metal chain and sprocket. That arrangement and operation of such a system is similar to that of the system using a rack and pinion described in the preceding embodiment.

In a second embodiment of the invention, the carriage control mechanism is based on a motor and a gearbox for lowering the bread. In this case, the motor drives the flywheel and thus the pinion to cause the pinion to move down the rack and the carriage to move to its lowered condition. The spring, rack and pinion and flywheel are used to control the upward movement of the carriage to return the carriage to its uppermost position, as described in the previous embodiment.

For smoothness of operation it is an advantage to have the weight of the motor and gearbox added to that of the carriage. In this way, the differences in weight of bread being toasted or the toasting of a single slice will not have a substantial effect on the total weight of the carriage assembly.

However, it is also envisaged that a configuration may also be used where the actuator is fixed to the body of the toaster and the rack moves with the carriage

If required, a magnet could be provided to control the speed of the flywheel. Either the magnet could be in close proximity to the flywheel to provide a damping effect or could be located over part of the path of movement of the carriage to act on the flywheel when it passes the magnet. Of course, in this arrangement the flywheel has to be of a ferro-magnetic material.

It is also envisaged that, in the case of a direct current motor, by short circuiting the motor's commutator connections, the back emf generated as the carriage rises will cause a magnetic braking force, thus requiring a smaller flywheel, or none at all. Whilst I have described herein specific embodiments of the invention it is envisaged that other embodiments of the invention will exhibit any number of and any combination of the features previously described and it is to be understood that variations and modifications in this can be made without departing from the spirit and scope thereof.

Claims

I claim:

1. A toaster of the 'pop-up' type having a body in which there is located a carriage which is moved downwardly to place the bread to be toasted adjacent the heating elements, and upwardly to permit the toast to be removed from the toaster characterised in that the upward movement of the carriage is controlled to provide a smooth delivery of the toast.

2. A toaster as claimed in claim 1 wherein the downward movement is against a return spring.

3. A toaster as claimed in claim 1 or claim 2 wherein there is a rack and pinion associated with the carriage the pinion being associated with a flywheel so that as the rack and pinion move relative to each other, the flywheel is caused to rotate and the inertia of the flywheel ensures that the relative movement is controlled.

4. A toaster as claimed in claim 3 wherein the rack is associated with the body of the toaster and the flywheel and pinion assembly is attached to the carriage so that any force endeavouring to move the carriage relative to the body will effect rotation of the flywheel and provide a resistance to the movement.

5. A toaster as claimed in claim 3 or claim 4 wherein there is a runner located on the side of the rack away from the pinion to ensure that the rack and the pinion teeth remain in contact.

6. A toaster as claimed in any preceding claim wherein the carriage, adjacent the upper end of its movement strikes a resistance so that it is slowed down positively until stopped.

7. A toaster as claimed in claim 6 wherein some part of the carriage strikes a resilient member, the displacement or deformation of which absorbs energy thereby acting as a retarding force for the carriage.

8. A toaster as claimed in claim 7 wherein the resilient member is a spring which extends downwardly into the toaster.

9. A toaster as claimed in claim 8 wherein the spring is generally N-shaped with the closed end being downwardly directed and the spring is compressed between two parts of the carriage.

10. A toaster as claimed in claim 9 wherein one of the parts of the carriage which contacts the spring comprises the periphery of the flywheel.

11. A toaster as claimed in any preceding claim wherein the downward movement is initiated by a user operating an handle extending from the body.

12. A toaster as claimed in any one of claims 1 to 10 wherein the downward movement of the carriage is effected by a motor driven movement of the carriage.

13. A toaster as claimed in claim 12 wherein the downward movement is initiated by placing at least one slice of bread in the toaster.

14. A toaster as claimed in any one of claims 11 to 13 wherein the carriage is moved against a return spring.

15. A toaster as claimed in claim 14 wherein at the completion of downward movement, the carriage is latched against further movement whilst toasting is occurring.

16. A toaster as claimed in claim 15 wherein on completion of cooking the latch is released to enable the carriage to return to its initial condition under the action of the spring.

17. and wherein the motor is rotated during this movement to give a retarding action against the force applied by the spring.

18. A toaster as claimed in claim 11 wherein the motor is an induction motor and wherein the rotation of the motor in the direction opposite to its normal movement induces a back emf which acts to resist rotation of the motor.