Auxiliary water tank and pump assembly for a concrete mixing vehicle

A self-purging auxiliary fluid supply system for supplying washout or makeup water or other fluids under pressure to a truck-mounted concrete mixing/dispensing drum is disclosed. The system includes a truck-mounted fluid reservoir for containing a quantity of fluid connected to supply fluid to an air-operated diaphragm pump connected to supply auxiliary fluid from the fluid reservoir under pressure to a discharge assembly. The pump further provides an integral purge system for displacing fluid in the fluid supply system after use.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to vehicle-mounted concrete mixing and dispensing systems and, more particularly, to on-board auxiliary fluid supply systems employed to supply water for washout or adding water to a concrete mix. Specifically, the present invention relates to a pump-operated on-board auxiliary fluid supply system that eliminates the need for a pressurized tank and is self purging of residual fluid.

II. Related Art

Transit concrete mixing trucks, sometimes referred to as ready-mix trucks, have long been in use. They are equipped with large chassis-mounted rotatable mixing drums for mixing and dispensing a quantity of concrete. The drums typically are mounted on an incline and have an opening in the upper end for receiving ingredients to be mixed and discharging mixed concrete products. Loading is accomplished through a charge hopper which extends a distance into the opening of the drum. The drum is further provided with internal helical flights or fins extending around its internal surface which acts to mix the concrete when the drum is caused to rotate in one direction and cause the concrete to be discharged out of the opening when the rotation of the drum is reversed. The upper portion of the drum includes a ring and roller system for drum support and rotation that is carried by a heavy pedestal support assembly.

After mixing and discharge, such concrete mixing drums retain an amount of residual concrete on the mixing fins and inner drum surface and discharge chutes which needs to be periodically washed out to prevent it from curing and hardening inside the drum and on external chutes. Therefore, it has become part of the operating routine to wash the interior of the drum and the discharge chutes one or more times per day. In addition, it may be necessary to add additional makeup water to a mix in the drum prior to discharge.

In conjunction with the use of makeup or washout water on transit concrete mixing trucks, it has further become a common practice to provide a water supply on the vehicle. The supply has included a water tank that has been typically pressurized to 50 psi or higher by a supply of air from a compressor carried on the truck. This, in turn, supplies water under pressure for washout or other uses through hoses and a valving system in a well-known manner.

Such a prior system is illustrated inFIGS. 1aand1bin which a concrete mixer truck, generally at10, having a mixing drum12and discharge chute14is provided with a pressurizable auxiliary water tank16mounted on the vehicle. As seen inFIG. 1b, the auxiliary water tank16includes an air inlet valve20that controls the flow of air under pressure from a pressure source (not shown) through an air supply line (also not shown). An air pressure regulator with gauge22is provided, together with a pressure relief or pop-off valve at24, which prevents over-pressurization of the system. A discharge outlet pipe or hose is provided at26suitably valved at28. The system may be purged by using pressurized air to clear the hose or pipe26.

More recently, however, government regulations have curtailed the use of such pressurized tanks in many areas and so it would be desirable to eliminate the need for pressurization of the tank without diminishing the washout or easy purge capabilities of the system.

SUMMARY OF THE INVENTION

By means of the present invention, there is provided a self-purging auxiliary fluid supply system for supplying water for washout or adding to batches in a truck-mounted concrete mixing drum. The system includes a truck-mounted fluid reservoir for containing a quantity of water, the reservoir being connected to supply non-pressurized fluid to a pump assembly. The pump assembly includes an air-operated diaphragm pump apparatus for supplying auxiliary fluid from the fluid reservoir under pressure to a discharge assembly which connects to a conventional washout/supply system associated with the operation of the mixing drum. The fluid supply system is provided with valving which enables it to quickly integrally purge itself after use.

Several embodiments are shown with different locations for the mounting of the pump of the invention. The system is designed for ease of manufacture or as a convenient retrofit system on existing transit concrete mixing trucks. The pump and piping system eliminate the need for pressurizing the reservoir tank and facilitate the draining or purging of associated water lines to prevent freezing in cold weather. A typical diaphragm pump of the invention uses air at about 100 psig to operate the pump and can supply up to 25 gpm of water at a pressure of about 10 psig for water injection or about 8 gpm at about 75 psig for washout.

DETAILED DESCRIPTION

Certain embodiments of the present invention will be described with reference to drawing figures. They represent examples of an auxiliary water supply system for a transit concrete mixing truck which provides high pressure water for washout or additional water to be added to the drum. The embodiments described are meant as examples and are not intended to limit the inventive concepts.

It is an important aspect of the present invention that the need for an expensive pressurized water supply tank is eliminated. In addition, the invention further provides a rapid self-purging feature to purge the system of water after use.

FIG. 2depicts an enlarged partial perspective view of an embodiment of the invention which includes a side or frame-mounted pump. The system includes an auxiliary water supply tank30which may be fabricated from metal or non-metal materials and is shown carried by support pedestals or saddles32,33fixed thereto by heavy straps34,35. Saddles32,33, in turn, are fixed to truck frame members36,38, respectively. An air-operated diaphragm pump40is mounted on a bracket42fixed to the truck frame member36. An air supply inlet connection is shown at44, which connects to an air pressure supply tank or accumulator which is pressurized by a conventional source of high pressure air such as a compressor (not shown) used to operate diaphragm pump40. The pump40has a suction inlet at46including a tee, one side of which is connected to a water feed line50which, in turn, is connected to the tank30at52.

The tank discharge is preferably a top discharge, bottom draw system using a conventional bottom draw standpipe tube (not shown) that is connected to outlet52at the top and extends to the bottom of the tank. This greatly facilitates hose system drainage after use. However, a bottom discharge arrangement can also be used. The tee also leads to a manually operated ball valve54used to drain and purge the system. The pump discharge outlet manifold shown at56is connected to a pump discharge hose58usable for washout or adding water to the drum. The water tank30is further provided with a breather vent60and fill opening62. The pump discharge hose58is connected to conventional suitable control valves (not shown) in a well known manner.

FIGS. 3aand3bdepict an alternative trailer-mounted embodiment which uses a mounting bracket70mounted flush with trailer frame member72. In this embodiment, the water feed line74is shown as being connected to a tank discharge outlet on the bottom of the tank30and the upper outlet52is suitably capped at76. Of course, a top discharge, bottom-draw connection could also be used. A ball valve is provided in the intake line at78. As best seen inFIG. 3b, the input/drain line between valves78and54is inclined slightly downward to valve54. This is to assure easy drainage when valve54is opened after the system is used.

Another embodiment is depicted inFIG. 4in which the air-operated diaphragm pump is mounted on the fluid supply tank itself. The pump is fixed to a mounting plate90which is mounted to the upper surface of the tank30. This embodiment also includes a water feed line50which accesses the tank30from the top at52and which also preferably uses a bottom draw standpipe system.

FIG. 5depicts yet another embodiment of an auxiliary fluid supply system in accordance with the invention in which the air-operated diaphragm pump40is mounted to the side of the fluid supply or water tank30. The pump is mounted on a bracket having a platform90and side members92. The bracket is attached to a stable mounting stand structure94which, in turn, is mounted on a truck alongside tank30in any convenient location in a well known manner. Connections between the tank and pump and the pump include top mounted water feed line50and discharge hose58. A drain valve54is also shown.

FIG. 6depicts an alternative embodiment of a water supply tank at100which is carried by a pair of spaced pedestals102and104and heavy attaching straps106and108. A fill opening is shown at110and a breather vent at112. A top discharge, bottom draw connection is shown at114with outlet hose116. The tank100further carries a smaller reservoir118containing additive material to be blended into the water supplied from the main auxiliary water supply tank100using supply hose120suitably valved at122, which can be manifolded with supply hose116at the pump input or other conventional mixer system in a well known manner.

In operation, with a supply of water or other desirable fluid in the tank30, the conventional output control valves (not shown) are opened in accordance with the use of the system and the diaphragm pump40is supplied with high pressure air, generally about 100 psig. The diaphragm pump40is operated to provide intake suction and pressurized fluid in the discharge line. When the desired amount of water is supplied for the desired use, the control valves in the pump discharge hose58and the drain/input valve54is opened. This allows water in the line to drain from the pump and also allows the pump to pump air through the system thereby purging out all the lines. This is particularly advantageous to avoid freezing of the system in cold weather.

This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.