FR2492309A1 - Automatic controller for addition of liquids during concrete mfr. - uses bi-directional pump operating through anti-parallel valve pair and regulated by multi-probe electronic liquid level sensor - Google Patents

Abstract

The additives are held in a ground level storage tank (1) and are pumped through an anti-parallel valve pair (8,9) into a clear cylinder (6) which has volume markings visible through a window (17) in the metal enclosing cabinet (5). Varios rods (13) are adjustable (14) for depth of immersion in the cylinder. The control circuit electrically detects contact of the liquid on the electrodes and sets the direction of pumping, i.e. to or from the cylinder. Anti-parallel valves (8,9) direct the fluid flow according to pumped direction. A light source is situated behind the cylinder (6), within the cabinet (5). The appts. is used to control the mixing of water in the mfr. of concrete.

Description

 The present invention relates to a liquid additive metering device for the industrial preparation of concrete.

 For the preparation of concrete, in addition to aggregates, sand, cement and water, liquid additives are currently used which have plasticizer, retarder or accelerator functions and which are also substituted in substantial mass proportions for cement. , these additives being poured with water into the mixer. The mixers, whatever their capacity, are arranged in height so that they can be unloaded in dumpsters and trucks while the adjuvant tanks, for reasons of com - modity and safety, in particular due to the toxic nature of the adjuvants, are provided at ground level, so that the adjuvant must be removed from the tank and mounted at the height of an overflow system in the mixer.

 For the metering of measured quantities of adjuvant to be poured into the mixer, a pneumatic system is currently used incorporated in the adjuvant distribution line and comprising a primary bell in the vicinity of the adjuvant tank and at cabin height control system for the concrete manufacturing installation, in accordance with the regulations in force, an electromagnetic dosing tube with linear magnet displacement, the outlet of which is connected to the water scale of the mixer located at a level raised relative to the dosing tube. For the implementation of this device, a first jet of pressurized air is sent to the bell to transfer a quantity of adjuvant to the dosing tube, after which, the determined quantity of adjuvant having been detected in the dosing tube, a second jet of pressurized air is sent into the dosing tube to expel this measured quantity of adjuvant towards the water scale.

 This system has a certain number of drawbacks due, on the one hand, to the complexity and delicacy of the pneumatic circuits and associated control means, and, on the other hand, to the related problems of clogging and 'Damage to the valves of the pneumatic circuits by the vapors released by the adjuvant in contact with the air under propulsion pressure, the adjuvant notably containing highly chlorinated products.

 The object of the present invention is to propose a device for dosing liquid admixture of concrete, of simple construction, of low cost price and of implementation, obviating the drawbacks of the previous systems while respecting the requirements of the regulations, capable of '' be presented in a compact form in an individual box, and can be easily installed in any existing installation.

 To do this, according to a characteristic of the present invention, the liquid admixture dosing device, of concrete comprises a dosing chamber with level detectors connected bypass to the adjuvant transfer line between the adjuvant tank and a discharge line in a mixer by a circuit element including two opposing valves in parallel, a reversible pump being arranged in the circuit element between the metering chamber and the valves.

 According to another characteristic of the present invention, the entire metering device is housed in a sealed box having a window, the chamber being made of transparent material.

Other characteristics and advantages of the present invention will emerge from the following description of an embodiment, given by way of illustration but in no way limiting, made in relation to the appended drawing in which
Figure 1 is a schematic representation of an installation for supplying liquid concrete admixture including a metering device according to the present invention.

As shown in FIG. 1, the concrete admixture distribution installation typically comprises an admixture tank 1, situated at ground level, a first pipe 2 for transferring the admixture to a metering station at an intermediate level corresponding to the installation's control cabin and a second pipe 3 for conveying metered quantities of adjuvant to a mixer 4. In accordance with the present invention, the metering device, advantageously integrated in a sealed box 5 , essentially comprises a transparent cylindrical metering chamber 6, for example made of polymethacrylate, a reversible pump 7, for example the three-phase pump sold under the reference group CS 5 by the company Jeumont
Schneider, and a set of two opposing valves 8 and 9. More specifically, the pump 7 is inserted in a circuit element 10 connecting the bottom of the chamber 6 to the adjacent ends of the two valves 8 and 9, the valve inlet 8 having its inlet orifice 11 connected to the adjuvant supply pipe 2, the outlet valve 9 having its outlet orifice 12 connected to the distribution pipe 3, the opposite passage orifices of these valves being connected to circuit element 10.

 According to the present invention, the metering chamber 6 is of the type with level detectors including a plurality of conductive rods 13 penetrating at different lengths into the internal volume of the chamber 6 and connected, by their free external ends, to a control block 14 also also connected to the pump 7. The rods 13 are adjusted and locked at the levels required by screw locking sleeves 15 mounted on the cover 16 of the chamber 6. The front face of the housing 5 is provided with a window 17 opposite the chamber 6, two bulbs 18 being provided at the rear of the chamber 6 to make the content of the latter visible even under difficult observation conditions.

Chamber 6 has one of its walls also advantageously provided with a graduated indicator 19 allowing a direct reading of the quantities of adjuvants contained in chamber 6.

 The operation of the device is as follows the operator starts the pump 7 in a first direction to suck the adjuvant from the reservoir 1 into the chamber 6, the inlet valve 8 then being open and the valve 9 closed. When the level of the adjuvant in the chamber 6 reaches one of the preselected levels determined by the rod detectors 13, the control system 14 provides a signal to stop the pump 7 then, after an adjustable delay time, an actuation signal from the pump 7 in the reverse direction to then extract the adjuvant contained in the chamber 6 and transfer it to the mixer 4, the outlet valve 9 then opening while the inlet valve 8 is closed. When the level of the adjuvant in the metering chamber 6 reaches the floor level, the control unit 14 orders the pump 7 to stop, so that the device is ready to carry out a new metering operation.

 Although the present invention has been described in relation to particular embodiments, it is not limited thereto but is on the contrary subject to modifications and variants which will appear to those skilled in the art. In particular, the chamber 6 can include a float coupled to an electrical contact at the top of the chamber to actuate an alarm light located on the front of the housing and prevent the adjuvant from overflowing in the event of failure of the detection system. level.

Claims (7)

 1 - Liquid concrete admixture metering device, intended to be inserted in an admixture transfer line from an admixture tank to a discharge pipe in a mixer, characterized in that it comprises a metering chamber (6) with level detectors (13) connected in diversion to the line (2,3) by a circuit element (10) comprising two opposing valves in parallel (8; 9), a reversible pump (7) being arranged in the circuit element between the chamber and the valves.  2 - Device according to claim 1, characterized in that the entire device is housed in a sealed case (5) having a viewing window (17), the chamber (6) being made of a transparent material.  3 - Device according to claim 2, characterized in that it comprises a control block (14) receiving the signals from the level detectors (13) and controlling the pump (7).  4 - Device according to any one of the preceding claims, characterized in that the metering chamber (6) comprises level detection rods (13) mounted in an adjustable manner on a cover (16) of the chamber.  5 - Device according to any one of claims 2 to 4, characterized in that it comprises an illuminating source (18) disposed behind the chamber (6) in the case (5).  6 - Device according to any one of the preceding claims, characterized in that it comprises integrated means (11, 12) for connection to the adjuvant transfer line (2, 3).  7 - Device according to any one of the preceding claims, characterized in that it comprises a separate security level detector.