Cement mixer attachment

Abstract

A mixer attachment 700 is provided for delivering water into a portable cement mixer having a static support frame and a rotatable drum with an opening. The mixer attachment comprising; a rigid tube (

Description

BACKGROUND Field of the Invention The invention relates to cement mixers, particularly portable cement mixers equipment to improve their functionality. Description of Related Art Portable cement mixers are intended for use on building sites, both commercial and domestic, to produce quantities of mortar or concrete suitable for laying bricks, paths and other such applications. Portable cement mixers are designed so that they can be moved around a site by one or two people and operated by a single person. A typical portable cement mixer 100 is shown in Figures 1A and 1B. In use, an operator shovels the dry elements of the mortar or concrete into the drum, such as cement and sand while another operator adds water from a bucket or hose. The operator typically stands near a supply of dry materials and loads a shovel with the dry materials; they then swing the loaded shovel up and into the mouth of the mixer. The efficiency of the process is determined by the accuracy of the operators’ swing and their rhythm. A problem with this system is that a second operator is required to add the water. Alternatively, a single operator can add the water but this interferes with the operator’s rhythm as they switch between shovel and bucket, and the efficiency of the process is reduced. Also, gauging the correct proportions of the mixture is difficult if a bucket of water is used, because it is easy for too much water to be added and then additional dry materials must be added to compensate. Alternatively, the operator may use a hose connected to a supply of water, but they still need to hold the hose and have a way to turn the water supply on and off, which is cumbersome and messy and requires them to stop loading the dry materials while they add the water. It is also desirable to direct the water into a particular part of the mixer drum to ensure efficient mixing of the load. The working environment for this type of equipment is harsh and equipment is prone to getting damaged. Any equipment used must be designed to minimise damage and to retain its optimum operational efficiency even if roughly handled. It is therefore an object of the present invention to overcome these problems. SUMMARY OF THE INVENTION In an embodiment, a mixer attachment is provided for delivering water into a portable cement mixer having a static support frame and a rotatable drum with an opening, the mixer attachment comprising; a rigid tube having a water inlet, and a water outlet, and at least two fixing regions for fixing the mixer attachment to the support frame of the cement mixer, the fixing regions including a first fixing region, wherein the tube in the first fixing region has a first axis, and a second fixing region, wherein the tube in the second fixing region has a second axis and wherein the first axis and the second axis are not aligned, , and wherein the water outlet is arranged in use to direct water into the drum of the cement mixer. In this way, an operator can devote themselves to shovelling dry materials into the mixer drum while the water is delivered into the mixer drum in a hands-free way by the mixer attachment. The mixer attachment is stabilised when attached to a cement mixer because the first axis and the second axis are not aligned. If pressure is applied to the water outlet, it will tend to twist the tube in the first region about its axis. By providing a second region with an axis that is not aligned with the axis of the first region, a resisting moment to the twisting force stabilises the mixer attachment. The mixer attachment can be roughly handled and it will continue to direct a water stream into the desired part of the mixer drum. The rigid tube of the mixer attachment may be arranged to hook around the opening of the drum of the cement mixer when the mixer attachment is attached to the cement mixer. In this way, the mixer attachment does not block or obscure the opening of the mixer drum. The rigid tube of the mixer attachment may be arranged to follow the external contours of the drum of the cement mixer when attached to the cement mixer. In this way, the profile of the mixer attachment when in use is minimised and the risk of it getting damaged is reduced. The water outlet of the mixer attachment may be arranged to be towards the top of the opening of the drum when the mixer attachment is attached to the cement mixer so that it delivers water into the centre of the mixer drum. A tap may be provided to control the flow of water into the drum of the mixer. The water inlet may have a fitting to connect to a hose. A first clamp may be provided in the first fixing region and a second clamp may be provided in the second fixing region to clamp the mixer attachment to the support frame of the cement mixer. The clamps may be arranged to release the mixer attachment from the support frame of the cement mixer when a predetermined force is applied to the mixer attachment. In another embodiment, a portable cement mixer is provided having a mixer attachment as described above. In another embodiment, a method of operating a portable cement mixer is provided, including the step of attaching a mixer attachment of the type described above to the portable cement mixer, attaching the mixer attachment to a supply of water and allowing water into the mixer drum. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a front view of a typical portable cement mixer. Figure 1B is a side view of a typical portable cement mixer. Figure 2 is a view of a mixer attachment. Figure 3A is a front view of a portable cement mixer with the mixer attachment shown in Figure 2 installed. Figure 3B is a side view of a portable cement mixer with the mixer attachment shown in Figure 2 installed. Figure 4A is an alternative view of a portable cement mixer with the mixer attachment shown in Figure 2 installed. Figure 4B is a detailed view of how the mixer attachment shown in Figure 2 is attached to a portable cement mixer. Figure 5A is a view of a snap-fit clamp for use with a mixer attachment. Figure 5B is a view of an alternative snap-fit clamp for use with a mixer attachment. Figure 6 is a front view of a cement mixer showing a target area for water loading. Figure 7A is a side view of the preferred embodiment of a mixer attachment. Figure 7B is a perspective view of the preferred embodiment of a mixer attachment on a cement mixer. Figure 8A is a view and a magnified view of a first clamp for attaching a mixer attachment to a cement mixer. Figure 8B is a view and a magnified view of a second clamp for attaching a mixer attachment to a cement mixer. Figure 9A is a perspective view of a clamp in the process of releasing the mixer attachment from a cement mixer. Figure 9B is a top view of a clamp in the process of releasing the mixer attachment from a cement mixer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The portable cement mixer 100 shown in Figures 1A and 1B has a drum with an open mouth for loading dry ingredients such as cement powder and aggregates such as sand and gravel. Water is added to achieve the correct consistency of mortar or concrete. The mixer has a rotating drum 101 that is mounted on a stand 102. The stand has wheels mounted on an axle, which are provided to move the mixer around the site and also arranged so that the contents in the drum can be tipped out into a suitable receptacle when mixing is complete. The rotating drum has substantially three regions; a main drum 101a, a transition 101b and a narrower opening 101c. The main drum 101a is where the ingredients are mixed, and it has internal vanes to assist the mixing process. The opening 101c is narrower than the main drum 101a to retain the mixture as it rotates; the diameter of the opening 101c must be large enough to allow an operator to shovel ingredients in without having to aim too accurately, while narrow enough to retain enough of the mixture in the main drum 101a until it is poured out. The transition 101b provides a smooth transition between the main drum 101 a and the opening 101 c, so that when the mixer is tipped to empty the contents, the contents pours smoothly out. A motor is provided within a housing 103 to rotate the drum. A portable cement mixer attachment is described below. The mixer attachment is arranged to supply a steady stream of water into the mouth of the mixer drum without an operator having to use their hands. When the mixer attachment is installed on a cement mixer, it is arranged to follow the profile of the drum and deliver water into the drum without obstructing the mouth of the drum, while also ensuring that the water is delivered into the centre of the inside of the drum where it can be most effectively mixed with the dry materials. The mixer attachment has a water outlet that is arranged within the mouth of the drum towards the top and tucked out of the way. In this way, the mixer attachment does not obstruct the mouth of the drum and thus the operator can maintain their usual swing as they shovel dry ingredients into the mixer mouth. A tap provides a consistent flow of water so that the rhythm of the user loading the dry ingredients is not interrupted. The operator may use a hand to adjust the flow of water with the tap if necessary. The parts of the mixer attachment that are external are arranged to follow the contours of the drum so that it minimises the risk of any part of it being knocked in the harsh environment of a building site. Meeting all of these requirements requires a specific geometry for the mixer attachment, as described below. A mixer attachment is shown in Figure 2. The mixer attachment comprises a rigid tube 201 having an inlet end 201a and an outlet end 201b. The rigid tube 201 is curved in specific places to enable it to overcome the problems described above, i.e. to not obscure the mouth of the mixer, to provide a consistent flow of water and to present a low profile so that it will not get knocked in the harsh environment of a building site. The inlet end 201a is provided with a hose attachment, such as a standard Hozelock™ connector for connecting to a hose. Alternatively a threaded connection between the mixer attachment and the hose may be provided. The hose is arranged to be connected to a source of mains water to provide water to the mixer attachment. The rigid tube 201 may include a tap 202 along its length for controlling the flow of water provided by the attachment into the mixer drum 101. The tap may be a lever-type tap where turning the lever through 90 degree moves the tap position from open to closed. Alternatively, the tap may be of a twist-type where twisting the tap in one direction starts and increases the water flow and twisting it in the opposite direction decreases and stops the water flow. The rigid tube 201 of the mixer attachment has different regions that are formed to solve the different problems described above. A tight curve 203, substantially 90 degrees, is formed beyond the water inlet 201a. Beyond the curve 203 is a straight fixing region 204. This combination of features allows the water inlet 201 a to be located low down on the mixer so that the hosepipe remains substantially flat on the ground when connected so that it doesn’t present a trip hazard on the building site. The straight fixing region is arranged so that it aligns with the upright stand 102 on the mixer. The straight fixing region 204 has a length that allows the mixer attachment to rise to be in line with the top of the drum 101. However, the mixer attachment is preferably arranged so that it does not present any height above the mixer drum and therefore uses the mixer drum to protect it in the building site environment. Clamps 204a and 204b are provided that are arranged to clamp onto the fixing region 204 of the mixer attachment and also onto the stand 102 of the cement mixer. At the end of the fixing region 204, curve 205 is provided in the rigid tube 201 leading to a further straight section 206. The straight section 206 is substantially the same length as the main drum 101a of the mixer. The straight section 206 curves into a further straight section 207a that is arranged to follow the transition part 101b of the mixer drum 101. This arrangement of the rigid tube 201 allows the mixer attachment to closely follow the external profile of the main drum 101a, so that the mixer attachment does not present unnecessarily any part that could be knocked or otherwise damaged. A tap 202 is provided in the straight section 206 to control the flow of water. It is located here so that an operator can easily reach it and the water flow adjusted during use. Sections 206 and 207a of the mixer attachment are twisted in relation to each other, so that the outlet 201 b of the mixer attachment is located high up in the mouth 101c of the mixer, as can be seen in Figure 3A. A tight curve 207b is provided in the rigid tube 201 towards its end, greater than 90 degrees, which returns the rigid tube 201 through the opening 101c of the mixer. A short section 207c of the rigid tube 201 is arranged to direct the water into the centre of the mixer drum. The effect of this section is to hook the mixer attachment around the opening of the mixer drum. The dimensions of the mixer attachment are such that it follows closely the profile of the mixer drum, including the main drum 101 a, the transition 101 b and the opening 101 c. Figures 3A and 3B show the mixer attachment in position. The position of the mixer attachment 301 in relation to the mouth of the mixer drum 302 can be seen in Figure 3A, where it is arranged so that it presents minimal obstruction in the mouth of the mixer drum. To install the mixer attachment on a cement mixer, the fixing region 304 is offered up to a vertical part of the stand of the mixer 102. Clamps 303a, 303b are used to clamp the fixing region of the mixer attachment to the stand. A hosepipe is then attached to the inlet end 201a. In use, an operator sets the flow of water into the mixer using the tap 202 and can then begin charging the mixer drum with dry materials. The mixer attachment provides a steady flow of water to the drum without the operator having to break their rhythm of charging the drum by shovelling the dry materials. The clamps used to hold the mixer attachment onto the mixer frame could alternatively be of a snap-fit type, as shown in Figures 5A and 5B. Figure 5A shows a clamp that is a single sided snap-fit fastener; the snap-fit part is arranged to receive the tubing of the mixer attachment, while the other side would include a fixed mounting (not shown) for encircling and clamping to the mixer frame, or vice versa. The snap-fit fasteners, also called push-fit, or snap-on fasteners or clamps, are annular in shape and are arranged to receive a tubular member; in use, the tubular member is offered up to the opening of the fastener and pushed against it. The snap-fit fasteners are made of a resilient material such as metal or plastic; when the tube is pushed against it, the fastener opens to receive the tube and then snaps closed around it to retain it in place. In an alternative embodiment, shown in Figure 5B, both the tube of the mixer attachment and the mixer frame are held together by snap-fit clamps. One or more snap fit fasteners may be used to hold the mixer attachment in place on the mixer. The advantage of using a snap-fit clamp or clamps is that if the mixer attachment is knocked or accidentally grabbed, the mixer attachment will come away from the mixer without damaging it. Clamps may be provided with insert shims to allow the mixer attachment to be used with different mixers that may have frames of varying sizes. The mixer attachment may be made from metal tubing, such as steel or copper, or it could be injection moulded in plastic. Some parts could be made from metal and some from plastic. The skilled person will appreciate that different size and shapes of mixer are available and the mixer attachment can be modified to fit any of these. In use, it is desirable to introduce water into the mixer drum in the upper left quadrant (when facing the mixer). This is a target zone, shown as “T” in Figure 6. Water will mix most efficiently with the dry materials if it arrives towards the back of this target zone. Water introduced in any other location does not mix well and can sometimes slop back out again and making a mess. It is therefore advantageous for water to consistently arrive in this optimum place. To meet this requirement, the mixer attachment should be rigidly fixed to the frame of the mixer so that it reliably delivers water into this place. Various factors can cause the mixer attachment to be moved and for the water stream to go off-target. For example, when the tap is operated, the mixer attachment can be moved if it is not secured firmly. In the harsh environment of a building site, users may “stab” the tap shut with the shovel they are using, which can knock the mixer attachment off target. Furthermore, during heavy use, the mixer drum can become caked in dry cement or otherwise distorted and this non-circular profile can also cause the mixer attachment to be knocked off target. An embodiment of the mixer attachment invention, shown in Figure 7A, addresses the above problem. A mixer attachment 700 is provided that has a first portion of tube, first fixing region 701, that is arranged to be attached to a first part of the mixer, and a second portion of tube, second fixing region 702, that is arranged to be attached to a second part of the mixer, where the first and second portions of tube are not axially aligned. Figure 7A shows the first portion of tube 701 having an axis A-A’, and a second portion of tube 702 having an axis B-B’, where axis A-A’ and axis B-B’ are not aligned, i.e. the axes are not coincident, there being an angle between them. The outlet end 703 of the mixer attachment has a large turning moment in relation to axis A-A’ and if the end 703 is knocked or pushed, it will tend to twist the attachment. If the mixer attachment is only connected to the mixer at points along axis A-A’, then it is likely that the turning force will be greater than the clamping force and the water flow will move to another sub-optimal location in the drum. Providing a second fixing region for the mixer attachment on a part of the cement mixer frame that is not aligned with A-A’ means that any turning moment applied to the end 703 will be resisted and the outlet will remain directed at the target zone, T. The embodiment is shown attached to a mixer in Figure 7B. The mixer has a drum D and a frame with a down-tube 704 and an attached, but non-axially aligned foot-tube 705. The mixer attachment 700 is fixed in two places; the first fixing region of the tube 701 is connected to the down-tube 704 and the second fixing region of the tube 702 is connected to the foot-tube 705. The angle, a, between axis A-A’ and axis B-B’ is selected so that the mixer attachment aligns with the two parts of the mixer frame, and is around 135 degrees, but could be greater or less than this. Figure 8 shows the clamps that are used to secure the mixer attachment to the mixer. The mixer attachment is fixed in two places; the first portion of the tube 801 is connected to the down-tube 802 by a first clamp 803; the second portion of the tube 804 is connected to the foot-tube 805 by a second clamp 806. The clamps are in two parts, held together by a bolt 807. The clamps are arranged so that the tube portions of the mixer attachment that are clamped can be released if it is put under a predetermined pressure, which prevents the attachment from getting damaged. Alternatively, the mixer attachment including the clamps can be released from the cement mixer frame if the mixer attachment is knocked. It would be possible to locate these fixing regions so that the mixer attachment could be attached to other parts of the mixer, as long as the parts of the mixer are not aligned, so that the tube of the mixer attachment can resist being turned by forces applied to its outlet end. Figure 9A shows a more detailed view of a clamp 901. The clamp is formed in 5 two halves of resilient plastic material; a first clamp half 901a and a second clamp half 901b. To attach the mixer attachment to the cement mixer, first clamp half 901a is offered up to the mixer attachment tube 902 and the cement mixer down tube 903. The second clamp half 901b is brought to and aligned with the first clamp half 901 a and the two clamp halves bolted together with bolt io 904. If the mixer attachment is knocked hard during use, the resilient plastic of the clamp deforms and opens to allow the mixer attachment to come away from the cement mixer; the part with reference numeral 905 in Figure 9A is shown opening to release the mixer attachment from the cement mixer. The opening of the clamp halves under pressure to release the mixer attachment from the is cement mixer 903 is also shown in an above view in Figure 9B.

Claims

1. A mixer attachment for delivering water into a portable cement mixer, wherein the portable cement mixer has a static support frame and a rotatable drum with an opening, the mixer attachment comprising;a rigid tube having a water inlet, anda water outlet, andat least two fixing regions for fixing the mixer attachment to the support frame of the cement mixer, the fixing regions including a first fixing region, wherein the tube in the first fixing region has a first axis, and a second fixing region, wherein the tube in the second fixing region has a second axisand wherein the first axis and the second axis are not aligned,and wherein the water outlet is arranged in use to direct water into the drum of the cement mixer.

2. The mixer attachment of claim 1, wherein the rigid tube of the mixer attachment is arranged to hook around the opening of the drum of the cement mixer when the mixer attachment is attached to the cement mixer.

3. The mixer attachment of claim 1 or 2, wherein the rigid tube of the mixer attachment is arranged to follow the external contours of the drum of the cement mixer when attached to the cement mixer.

4. The mixer attachment of any preceding claim, wherein the water outlet of the mixer attachment is arranged to be towards the top of the opening of the drum when the mixer attachment is attached to the cement mixer.

5. The mixer attachment of any preceding claim, wherein a tap is provided to control the flow of water into the drum of the mixer.

6. The mixer attachment of any preceding claim, wherein the water inlet has a fitting to connect to a hose.

7. The mixer attachment of any preceding claim, wherein a first clamp is provided in the first fixing region and a second clamp is provided in the second fixing region to clamp the mixer attachment to the support frame of the cement mixer.

8. The mixer attachment of claim 7, wherein the first clamp is arranged to clamp to a down tube of the mixer and wherein the second clamp is arranged to clamp a foot tube of the mixer.

9. The mixer attachment of claim 8, wherein the clamps are arranged to release the mixer attachment from the support frame of the cement mixer when a predetermined force is applied to the mixer attachment.

10. A portable cement mixer having a mixer attachment as claimed in claims 1 to 9.

11. A method of operating a portable cement mixer, including the steps of: attaching a mixer attachment of the type claimed in claims 1 to 9 to the portable cement mixer, attaching the mixer attachment to a supply of water and allowing water into the mixer drum.

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