WO2010094954A1

WO2010094954A1 - Concrete mixer

Info

Publication number: WO2010094954A1
Application number: PCT/GB2010/050255
Authority: WO
Inventors: Leslie Frederick Brown; David Henry Fryett
Original assignee: Leslie Frederick Brown; David Henry Fryett
Priority date: 2009-02-17
Filing date: 2010-02-16
Publication date: 2010-08-26
Also published as: GB2467789A; GB0902573D0

Abstract

A portable mixer for mixing concrete or like materials comprises a mixing container (1) which is in use non-rotating and is inclined at an angle to vertical. A lid (2) for the container is secured to the container by one or more clamping means. A mixing paddle is arranged to rotate through the material to be mixed and the free space above. A motor mounted within the lid drives the mixing paddle within the container. A leg arrangement (4, 5) provides a stable seating for the container with the container inclined to the vertical.

Description

Concrete Mixer

This invention relates to a powered mixer of the type suited to the mixing of concrete and cement.

Powered mixers are often used for the mixing of concrete and cement materials in preference to manual mixing of the materials and water on the ground using a spade or shovel. This is because the manual process is messy due to the water required and significant physical effort is also required to lift and mix the heavy materials.

Mixers used for the mixing of concrete materials are predominantly of two types; the first type is one where the mixing drum or container is broadly cylindrical and is rotated about its cylindrical axis by a motor. The motor may be electrical or an internal combustion type and may be connected to the drum directly or indirectly by a set of gears or belts. The axis of rotation is inclined from the vertical so that rotation of the drum causes the mixture contained within to tumble due to gravity, aided in some instances by fences or paddles fixed to the inside curved surface of the drum.

The second type is one having a broadly cylindrical container, fixed such that its cylindrical axis is aligned to vertical. A paddle is located within the container, motor driven from above or below depending on manufacturer preference, such that materials within the container are mixed as the paddle rotates. Unlike the machine type described in the first instance above, this mixer requires that the paddle pass continuously and without interruption through the volume of concrete material lying static in the base of the container. The mass of the material and relatively large granular structure is resistant to passage of the paddle and significant power is required to achieve satisfactory mixing.

For the purposes of this document, cylindrical means a shape that is nominally round in section but may vary in diameter along its length, by example, tapered, curved or barrel shaped. Mixers of the first type above are more common. A mixer typical of this type is described in US patent no. US 6,220,744.

Mixers of the first type described are generally quite substantial, being constructed with much metal content, and despite often having provision to separate the drum from the frame, disassemble the frame, and wheels for mobility, the machines are relatively large, heavy and inconvenient to transport and store.

The mixture, when blended to the required consistency, must be removed from the mixer by transferring to another container i.e. barrow, bucket or mortar board, for relocation to the point of application. This is often inconvenient.

Mixers of the types described above are generally not suited to preparation of small batches of mixture as with insufficient material content, the material sticks to the drum interior without tumbling and mixing.

Various attempts have been made to produce mixers suited to the preparation of smaller batch quantities of cement and concrete and at reduced cost. These mixers are generally miniaturised versions of larger mixers and maintain the same key components including an inclined rotating drum, a support means for the drum, a drum drive mechanism and a support frame for the whole assembly. Realisation of significant cost reduction is not achieved due to the significant number of parts still required. A mixer typical of this miniaturised type is described in US 2006/0028913.

Mixers of most types described above feature external moving parts, often including the drum itself and any exposed elements of the drive mechanism. Such moving parts present a significant hazard of injury to persons due to the opportunity for entrapment.

To overcome the inconveniences of size, mass and the element of danger presented by conventional mixers, the present invention proposes a portable safety mixer convenient for the mixing of small batches of cement, concrete or similar compositions.

According to the invention, there is provided a portable mixer for mixing concrete or like materials comprising: a mixing container which is in use non-rotating and is inclined at an angle to vertical; a lid for the container; clamping means for securing the lid to the container; a mixing paddle arranged to rotate through the material to be mixed and the free space above; a motor mounted within the lid to secure and drive the mixing paddle within the container, the rotation axis of the paddle being coincident with or near an elongate axis of the container; a leg arrangement providing a stable seating for the container with the container inclined to the vertical.

The invention eliminates the requirement for many previously essential parts including a mounting frame. The invention is particularly suited to manufacture from plastics to reduce mass and manufacturing costs.

The invention proposes a mixer comprised of an inclined, circular cross section, container to accommodate the materials to be mixed and fitted with a lid assembly housing an electric motor, drive components and a paddle arranged to scoop and lift and displace the materials within the container to achieve adequate mixing without demands of high power. The container is fixed in relation to the lid assembly and cannot rotate. The paddle, motor and drive components are all contained and present no entrapment hazard as no moving parts are externally exposed during operation.

In one example, the assembly does not feature a separate supporting frame of any sort as the lid is provided with two demountable legs and the mixer is inclined for operation with the two legs and a point on the container base providing a stable three point contact with the ground. In the preferred embodiment construction is predominantly from suitable thermoplastic materials to minimise mass and the reduced number of parts enables significant cost reduction to be realised. The two legs are easily removable to facilitate compact packaging for retail sale and subsequent storage by the user.

Filling of the container is undertaken with the assembly arranged such that the container is upright on its base and with the lid not fitted. In one example, the lid assembly is then secured to the container by two or more retaining latches and the assembly tilted until the leg arrangement is in contact with the ground.

Electrical switches can be provided on the lid assembly to enable the mixer to be turned on or off as desired. A preferred embodiment incorporates a timer to automatically terminate the mixing cycle after a predetermined time period. A second preferred embodiment incorporates a tilt sensitive switch such that the mixer may not be set to operate if the assembly is not first tilted and seated on its three point footprint.

The lid assembly can feature a sensor to detect the presence of the container and ensure that the paddle cannot be powered if the container is absent and the paddle exposed.

The lid assembly may optionally feature a hinged or sliding cover to an access aperture for viewing of the container contents without requiring removal of the lid assembly. In instances where the access cover is present, a sensor shall be fitted such that the paddle power is interrupted whenever the cover is opened. An alternative embodiment is a viewing aperture provisioned with a fixed grill sized to prevent insertion of body parts i.e. fingers.

The container can feature a handle such that the container, inclusive of its mixed contents, may be conveniently carried to wherever the mix is required for use. Advantages of the possible examples of device made in accordance with the invention include, but are not limited to:

The mixer can have no external moving parts to present a safety hazard;

The mixer can have fewer parts than conventional mixers so can be manufactured at lower cost;

The mixer can have parts ideally suited to manufacture as plastic moulded parts to reduce cost;

The mixer can be suited to the mixing of smaller batches of concrete or like materials;

The mixing container can have a handle making it practical to move the mixed materials directly to the point of application;

The mixer can reduce to a compact size for storage and retail sale;

The invention also provides a method of mixing concrete or like materials, comprising: placing the materials to be mixed in a mixing container fitting a lid over the container, the lid carrying a mixing paddle arranged to rotate through the material to be mixed and carrying a motor to secure and drive the mixing paddle within the container, wherein with the lid fitted, the rotation axis of the paddle is coincident with or near an elongate axis of the container; mounting the container at an angle to vertical; and operating the motor to mix the materials.

Examples of the invention will now be described by referring to the accompanying drawings, in which:

FIGURE 1 : Shows a mixer according to one embodiment of the invention FIGURE 2: Shows a mixer as in figure 1 with an optional viewing port open.

FIGURE 3: Shows a vertical cross section view of the mixer about its cylindrical axis.

FIGURE 4: Shows the mixer with the container removed to show a paddle

FIGURE 5: Shows the paddle removable from the drive spindle

FIGURE 6: Shows an over centre lid retaining latch in closed position

FIGURE 7: Shows an over centre lid retaining latch in open position

FIGURE 8: Shows the lid assembly, illustrating the container locating key recesses

FIGURE 9: Shows the container, illustrating the projecting anti rotation keys

FIGURE 10: Shows the removable legs separated and located for transit

FIGURE 1 1 : Shows the mixer with demounted legs in a typical retail packaging box.

In figure 1 , a container 1 is attached to a lid assembly 2 by means of securing latches 3. Lid assembly 2 is fitted with two removable legs 4 and 5 such that the whole assembly may rest on the ground, in a stable three point contact configuration, with the cylindrical axis of the assembly at an inclined angle with respect to the ground.

An optional hinged viewing cover 6 is illustrated in its closed position. A switch panel 7 is shown and features on and off power buttons to control electrical function of the mixer. In figure 2, an optional hinged viewing cover 6 is illustrated in its open position.

If a viewing cover is fitted, there is also an electrical sensor switch located to ensure that function of the mixer is inhibited if the cover is opened.

In figure 3, a sectional view of the mixer about its central axis, item 1 is illustrated attached to the lid assembly 2 and front legs 4 and 5 such that the central axis of the mixer is inclined with respect to the ground. A paddle 8 is removably attached to a coaxially located drive shaft 11 and driven by a gear train 10 by an electrical motor 9. The lid assembly 2 features a carry handle 12 to aid removal of the lid assembly from the container 1 when required.

In figure 4, the lid assembly is illustrated with the container 1 removed to more clearly show the paddle 8.

In figure 5, the paddle is shown removed from the drive shaft 1 1. The drive shaft and paddle are square or otherwise keyed to prevent respective rotation of the two parts about their axis.

In figure 6, the lid assembly retaining latch 2 is illustrated in its latched position, securing the container 1 to the lid assembly 2.

In figure 7, the latch from figure 6 is shown in its open position.

The preferred embodiment of the latch is an over centre toggle type as illustrated but other means of securing the container may be utilised including for example, hooks operated by a threaded knob such that tightening of a knob causes a hook to tighten under the rim of the container.

In figure 8, the lid assembly is illustrated to show a preferred embodiment of two receptacles 13 and 14 provided to locate the projecting anti rotation keys 15 and 16 on the container 1 . Alternative means may be embodied to prevent respective rotation of the lid with respect to the container yet permit rapid disengagement of the two parts. By way of example, the number of keys may be more or less or different in size and shape.

In figure 9, the container is illustrated to show two projecting keys 15 and 16. A carry handle 17 is also illustrated.

In figure 10, the mixer is illustrated with the two legs 4 and 5 demounted and laid alongside the mixer for storage when not in use. In the preferred embodiment the legs are each provided with a latch to retain each leg in its respective receptacle on the lid until released for storage.

In figure 11 , the mixer is illustrated within a retail packing carton 18 to illustrate the compact nature of the mixer when not in use.

The preferred embodiment of the invention uses an electric motor powered from the mains electrical supply and requires a cable connection between the mixer and the power source.

Alternatively, the mixer may be powered using an integral or plug in battery pack such that the mixer becomes a 'cordless' device.

A second alternative is that the mixer is powered by an integral small internal combustion engine.

A third alternative is that the mixer features an external crank for rotation manually by the user.

The paddle 8 is illustrated in one embodiment designed to pass closely to the container inner surfaces and feature alternating short blades to reduce the power requirement.

It will be appreciated that various alternatives to the mixer described hereinbefore can be made including: The two legs may be non detachable from the mixer lid but hinged to lay alongside the container to minimise stowed volume;

The leg section may be square, rectangular, circular or any other shape alternative to the preferred triangular profile;

Construction may be from metals in place of plastics;

The paddle may have one or more blade surfaces and each may not be planar; The motor may be programmable in speed and duration by means of control electronics and a timer;

The transmission between the motor and paddle may have selectable speed ratios;

The base of the bucket may be flat or internally convex to aid mixing;

The legs may feature feet made from high friction material i.e. rubber to reduce slipping;

The mixer lid may be fitted with a removable membrane between the lid and the bucket, manufactured from a flexible material i.e. rubber, to aid cleaning. The membrane may incorporate sealing features between the bucket and the lid and the lid and the central drive shaft. To clean encrusted and hardened concrete material from the membrane it is undipped from the lid and flexed until the materials have de-bonded;

In the example shown, the base of the bucket rests on the ground to define one point of a three point stable footing. However, there may be a third leg at the base of the bucket, or a flattened area may be provided at the base of the bucket to define a foot. Also, the bucket may have no support legs, but a separate cage can be provided into which the bucket (with fitted lid) is seated. This cage then defines the required leg arrangement. The leg arrangement can thus have a single leg, in the form of a platform for mounting on flat ground, and a structure for receiving the bucket at the desired angle of inclination.

The leg arrangement should prevent rotation of the bucket and lid when the paddle is driven.

The use of a leg arrangement as part of the lid is preferred, as it can be dismounted, and even stored in the bucket, to make easy storage for the user.

The device of the invention is particularly suitable for small quantities. Thus, the container volume is typically less than 45 litres, more preferably in the range 25 to 35 litres.

The device is inclined at an angle to the vertical in use. The container is typically filled in the vertical orientation (sitting on a flat base of the container), and then it is inclined. The angle to the vertical is preferably more than 30 degrees. The mixing then combines stirring with folding to promote even mixing. In practice, the angle can be much greater, and indeed the container can be closer to the horizontal. For example, a preferred range of angles is 15 to 50 up from the horizontal (i.e. 40 to 75 degrees from the vertical).

Various other modifications will be apparent to those skilled in the art.

Claims

1 , A portable mixer for mixing concrete or like materials comprising: a mixing container which is in use non-rotating and is inclined at an angle to vertical; a lid for the container; clamping means for securing the lid to the container; a mixing paddle arranged to rotate through the material to be mixed and the free space above; a motor mounted within the lid to secure and drive the mixing paddle within the container, the rotation axis of the paddle being coincident with or near an elongate axis of the container; a leg arrangement providing a stable seating for the container with the container inclined to the vertical.

2. A mixer as claimed in claim 1 , wherein the leg arrangement is fitted to the lid and located such that its contact with the ground and the contact of the container with the ground provide a stable seating on the ground.

3. A mixer as claimed in any preceding claim, wherein the leg arrangement comprises two legs, and the leg arrangement and the contact of the container with the ground provide a stable three point seating on the ground.

4. A mixer as claimed in claim 3, wherein the two legs are demountable from the container for storage.

5. A mixer as claimed in any preceding claim, wherein the container has a generally circular cross section perpendicular to the elongate axis.

6. A mixer as claimed in any preceding claim, wherein the container has a carrying handle.

7. A mixer as claimed in claim any preceding claim, wherein the container comprises a bucket.

8. A mixer as claimed in any preceding claim, having no external moving parts powered by the motor.

9. A mixer as claimed in any preceding claim, further comprising a tilt sensitive switch arranged to allow operation only if the assembly is tilted and seated with its stable seating.

10. A mixer as claimed in any preceding claim, wherein the lid assembly comprises a cover to an access aperture for viewing of the container contents without requiring removal of the lid assembly.

11. A mixer as claimed in claim 10, comprising a sensor for interrupting power to the mixing paddle when the cover is opened.

12. A mixer as claimed in any preceding claim, wherein the container is in use inclined at an angle of more than 30 degrees to the vertical.

13. A method of mixing concrete or like materials, comprising: placing the materials to be mixed in a mixing container fitting a lid over the container, the lid carrying a mixing paddle arranged to rotate through the material to be mixed and carrying a motor to secure and drive the mixing paddle within the container, wherein with the lid fitted, the rotation axis of the paddle is coincident with or near an elongate axis of the container; mounting the container at an angle to vertical; and operating the motor to mix the materials.

14. A method as claimed in claim 13, wherein the container is mounted at an angle of more than 30 degrees to the vertical.

15. A method as claimed in claim 13 or 14, wherein mounting the container comprises using a leg arrangement which is fitted to the lid to form a stable seating on the ground, the stable seating comprising the ground contact of the leg arrangement as well as the contact with the ground of the base of the container.