GB2388055A

GB2388055A - Concrete mixer with water flow sensor on water supply

Info

Publication number: GB2388055A
Application number: GB0204968A
Authority: GB
Inventors: John H Gingell; Grahame Neagus
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-03-02
Filing date: 2002-03-02
Publication date: 2003-11-05
Anticipated expiration: 2022-03-02
Also published as: GB0204968D0; GB2388055B

Abstract

The detection and monitoring of any unauthorised addition of water to the concrete mix in a concrete mixer drum (14) is accomplished by means of water flow sensor (32) so that the strength of the concrete is not inadvertently diluted by the addition of water. Water in a tank (28) has to travel to the drum (14) via an in-line water flow sensor (32). A drum rotation lever (24) is arranged to actuate a switch (56) in a control box (22). If the sensor (32) detects that water is flowing and if simultaneously the drum rotation lever (24) is in any position other than that for the discharging of the concrete from the drum, then an alarm signal is generated. The alarm signal may be sent to telemetry unit (60) in cab (12) for transmission via aerial (62) to a remote receiving station.

Description

( 2388055

CONCRETE M I XERS

This invention relates to concrete mixers and is particularly concerned with concrete mixers which are mounted 5 on vehicles and which are designed to deliver loads of concrete to sites in the vicinity of a batching plant. It is also concerned with methods of monitoring drum rotation and water flow to a mixer drum.

Within the construction industry, there has long been a 10 concern over the final strength of concrete supplied on site to any contract. The concrete is delivered to the site by a concrete mixer vehicle, usually of 4, 6, 7, 8, or 9 cubic metre capacity, having been mixed at the batching plant where precise combinations of cement, sand and water are added to 15 the mixer drum so that the required strength of mix can be delivered to the client on site. Concrete never loses strength once it is mixed, provided that nothing is added to the mix. The only exception to this is the addition of water to the mix. The adding of water has the net result of 20 weakening the final mix, especially if large quantities of water are added prior to delivery. Concrete mixer vehicles have, as a standard f itment, a water tank to enable the driver to wash down the delivery chutes and other associated parts after delivery of the concrete. It is through the 25 introduction of water from this tank that the mix can be

adulterated and be reduced in its actual strength.

Currently, there is no means by which an operator or concrete provider can assess whether or not additional water has been added to the load after the vehicle leaves the batching plant 30 and prior to delivery on site.

( At the batching plant, the mixer drum is charged with cement, sand and water. On the vehicle there is a drum rotation lever by means of which the rotation of the drum is controlled. With the lever in a neutral position the drum 5 does not rotate, i.e. it is static. Movement of the lever in one rotational direction from neutral will cause the drum to rotate, with increasing speed as the lever is moved further from the neutral position. Movement of the lever in the opposite rotational direction from neutral will cause the 10 drum to discharge its contents. In practice, at the batching plant, the drum is rotated relatively fast until the drum contents are thoroughly mixed. The driver will then ease back the control lever so that the drum rotates at 1 to 2 revolutions per minute and so that the mix is agitated as the 15 vehicle is driven to the delivery site. At the site the driver will put the control lever in neutral to stop rotation of the drum and will then move the lever in the sense to discharge the drum contents.

It is an object of the present invention to provide a 20 method and apparatus by means of which one can monitor the flow of water from the water tank when the mixer drum is either static or in a mixing mode, i.e. when the drum is rotating. In this way one can detect the addition of water at any time after the mix has been manufactured at the 25 batching plant.

It is a further object of the invention to provide a method and apparatus which will monitor any unauthorized addition of water to the concrete mix and will actuate detection means when such water is added to the mix, thereby 30 to send a message to a remote location and/or record the

( event. Broadly in accordance with the invention there is provided a method of monitoring the supply of water to a rotatable concrete mixer drum, which comprises providing 5 water flow sensing means in the water supply to the drum, detecting the mode of rotation of the drum, and generating an output signal in response to a signal from the water flow sensing means when the drum is static or in a mixing mode.

Also broadly in accordance with the invention there is 10 provided apparatus for monitoring the supply of water to a rotatable concrete mixer drum, comprising water flow sensing means arranged to be fitted in a water supply to the drum and to generate a first output signal in response to water flow, means arranged to detect the mode of rotation of the drum and 15 to generate a second output signal in response to the drum being static or in a mixing mode, and data processing means arranged to generate an alarm signal in response to the simultaneous presence of said first and second output signals. 20 In order that the invention may be more fully understood, one presently preferred embodiment of a system in accordance with the invention will now be described by way of example and with reference to the accompanying drawings. In the drawings: 25 Fig. 1 is a schematic diagram of a concrete mixer vehicle equipped with a detection system in accordance with the invention; Fig. 2 is a schematic diagram, on an enlarged scale, of the water flow sensor of the detection system; 30 Fig. 3 is a schematic diagram of the drum rotation

( control box; Fig. 4 is a side view of the drum rotation control box of Fig. 3 as installed; and, Fig. 5 is a schematic wiring diagram for the detection 5 system.

Referring now to the drawings, there is shown in Fig. 1 the basic elements of the detection system of the present invention. The chassis of a concrete mixer vehicle is indicated at 10 and the vehicle cab is indicated generally at 10 12. Mounted rearwardly of the cab 12 is a mixing drum 14 into which sand, cement and water are added through a rearwardly facing inlet aperture 16. A gearbox and motor for rotating the drum 14 are indicated at 18. The gearbox and motor 18 are mounted on a support 20 on the chassis of the 15 vehicle. A control box 22 is mounted towards the rear of the vehicle. Protruding from the control box 22 is a drum rotation lever 24 which is arranged for pivotal movement to each side of a central, neutral position in order to control the speed of rotation of the drum and the change from a 20 mixing mode to a discharge mode. The control box 22 is also provided with a locking handle 26 on the exterior of the box.

This locking handle is used by the driver to lock the rotation lever 24 in a set position, for example when driving from the batching plant to a site, and is intended to prevent 25 the setting of the rotational lever 24 from changing due to vibration. The drum rotational lever 24 is duplicated in the cab 12, so that the driver has control over this lever both from the cab and from the rear of the vehicle.

The vehicle is fitted with a water tank 28 from which a 30 water pipe 30, for example of steel, extends to the rear of

( the vehicle and into the drum 14, so that water can be added to the mix within the drum. The valves and pressure gauges which are required for the supply of water from the tank 28 to the drum 14 are not shown.

5 In accordance with the invention there is provided in the water supply pipe 30 an in-line water flow sensor which is indicated generally at 32. This sensor 32 is shown most clearly in Fig. 2. The direction of water flow is indicated by arrows 34. The sensor per se is indicated at 36 and an 10 electrical lead 38 runs from the sensor 36 to the cab 12.

The sensor 36 has male connecting portions 40, 40' above and below the unit. These male connecting portions are fitted into respective alloy cones 42, 42' which are themselves secured by clips 44, 44' to lengths of rubber tubing 46, 46 ' 15 which are connected to the water pipe 30.

As shown in Figs. 3 and 4, the control box 22 is mounted on a back plate 48 which is secured to or is part of the vehicle. The drum rotation lever 24 is mounted on a hub SO and is enabled to traverse by the provision of a slot 52 20 which is provided in the base of the control box 22.

Extending from the hub 50 is a splined shaft 54 which, at the front of the control box 22, is connected to the locking handle 26. Within the control box 22 there is mounted a microswitch indicated generally at 56 in Fig. 3. The 25 microswitch 56 is mounted on the rear wall of the control box in a rubber gaiter which in turn is housed within a waterproof UPVC case. An electrical lead 58 is connected from the microswitch 56 to the vehicle cab 12. This wiring is protected in a conduit with waterproof seals. The 30 microswitch 56 is arranged to be actuated by movement of the

drum rotation lever 24. The arrangement is such that when the drum rotation lever 24 is in its neutral position or in any charging position an "active)' signal will be sent from the microswitch 56 to the cab. When the drum rotation lever 5 24 is in its discharge position the microswitch 56 is deactivated. Within the cab 12 is a telemetry unit 60 and a fuse board and power supply 62. The telemetry unit preferably has a GPS location function, as well as a built-in modem and sim 10 card, for the transmission of data to a remote receiving station. An aerial 62 is fitted and installed to the cab for this purpose. Signals from the vehicle are transmitted to a receiving office or computer at a remote location, thereby providing information as to the fact that water is being 15 supplied to the mix and also as to the real time location of the event and/or vehicle. The sensor and telemetry are preferably such that they will record not only the fact that water is being added to the mix, but also the volume and/or rate of flow of water, as desired. In this way the fact 20 that the mix has been adulterated, or not as the case may be, can be monitored.

Fig. 5 shows a schematic wiring diagram for the detector system. The wiring harness from the microswitch and from the water sensor is protected within a conduit with waterproof 25 seals, finishing within the telemetry unit 60. This telemetry unit 60 can be housed either within the cab as shown or alternatively externally towards the cab end of the chassis. Wiring into either digital or analogue channels of the unit results in the required data information being 30 recorded and then transmitted to the base station.

( Although the invention has been described above in relation to a concrete mixer mounted on a vehicle, the invention is also applicable to the monitoring of static concrete mixing machines.

5 The monitoring system of the present invention can be fitted to new vehicles and machines and can also be supplied for retrofitting to existing vehicles and machines.

Claims

CLAIMS:

1. A method of monitoring the supply of water to a rotatable concrete mixer drum, which comprises providing water 5 flow sensing means in the water supply to the drum, detecting the mode of rotation of the drum, and generating an output signal in response to a signal from the water flow sensing means when the drum is static or in a mixing mode.

2. A method of monitoring the supply of water to a 10 rotatable concrete mixer drum, which comprises providing water flow sensing means in the water supply to the drum, detecting the mode of rotation of the drum, and generating an output signal in response to a signal from the water flow sensing means when the drum is in a mixing mode.

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3. A method according to claim 1, or 2, in which the detection of the mode of rotation of the drum is effected by a drum rotation control lever being arranged to actuate switching means.

4. A method according to claim 1, 2 or 3, in which the 20 water flow sensing means is located in a pipe between a water reservoir and the mixer drum.

5. Apparatus for monitoring the supply of water to a rotatable concrete mixer drum, comprising water flow sensing means arranged to be fitted in a water supply to the drum and 25 to generate a first output signal in response to water flow, means arranged to detect the mode of rotation of the drum and to generate a second output signal in response to the drum being static or in a mixing mode, and data processing means arranged to generate an alarm signal in response to the 30 simultaneous presence of said first and second output signals.

6. Apparatus for monitoring the supply of water to a

rotatable concrete mixer drum, comprising water flow sensing means arranged to be fitted in a water supply to the drum and to generate a first output signal in response to water flow, means arranged to detect the mode of rotation of the drum and 5 to generate a second output signal in response to the drum being in a mixing mode, and data processing means arranged to generate an alarm signal in response to the simultaneous presence of said first and second output signals.

7. Apparatus according to claim 5 or 6, which includes 10 a water reservoir, and a supply pipe from the reservoir to the drum, with the flow sensing means incorporated into the supply pipe.

8. Apparatus according to claim 5 or 6, in which the means to detect the mode of rotation of the drum comprises a 15 drum rotation control lever and switching means arranged to be actuated in dependence on the position of the control lever.

9. Apparatus according to claim 8, in which the control lever is pivotable within a housing to each side of a central 20 neutral position, movement to one side controlling the speed of rotation of the drum, and movement to the other side effecting a change from a mixing mode to a discharge mode of the drum.

TO. Apparatus according to claim 5 or 6, in which the 25 means to detect the mode of rotation of the drum comprises a pressure switch.

11. Apparatus according to claim 10, in which the pressure switch has contacts which are closed when the drum is mixing and are open when the drum is discharging.

30

12. A method substantially as hereinbefore described with reference to the accompanying drawings.

13. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.