GB2132283A

GB2132283A - A pump for delivering several different products in well defined proportions

Info

Publication number: GB2132283A
Application number: GB08330345A
Authority: GB
Inventors: Michel Binosche
Original assignee: SKM SA
Current assignee: SKM SA
Priority date: 1982-11-19
Filing date: 1983-11-14
Publication date: 1984-07-04
Also published as: FR2536471A1; DE3341783A1; FR2536471B1; JPS59103975A; GB8330345D0; DE3341783C2

Abstract

The invention provides a pump formed by a single actuator whose piston (2), during its delivery stroke, causes simultaneous sliding, by the same amount or by proportional amounts, of a number of pistons (5, 6) equal to that of the constituents of the mixture, the sections of these pistons (5, 6) depending on the desired flowrate for each of them, suitably controlled amounts of which may escape therefrom towards the point of use. It further comprises means such that sliding of the actuator piston (2) in the delivery direction can only take place if all the cylinders (9, 10) assigned to each of the components of the products to be mixed are completely filled. In one embodiment, uncoupling of the actuator piston (2) and of the cylinders (9, 10) containing the products to be mixed occurs automatically as soon as the actuator piston (2) begins its return stroke and is only re-established for the delivery stroke when all the cylinders (9, 10) have been completely filled. <IMAGE>

Description

SPECIFICATION A pump for delivering several different products in well defined proportions Background of the Invention 1. Field of the Invention It is frequently required to deliver in well defined proportions several different products, such as compounds polymerisable by action of reagents, paints or adhesives, which cannot be mixed beforehand but only at the time of use thereof.

2. Description of the PriorArt To obtain this result, it is known to use a single actuator whose piston, during its delivery stroke, causes simultaneous sliding, by the same amount or by proportional amounts, of a number of pistons equal to the number of constituents of the mixture, which pistons have sections depending on the desired flowrate for each of these constituents, in cylinders assigned to each of them, of which suitably controlled amounts may escape therefrom in the direction of the point of use through ducts provided with non-return valves, whereas, during its return stroke, the piston of the above-mentioned actuator causes or allows simultaneous sliding, by the same amount or by proportional amounts, of the same pistons in the cylinders assigned to each of these components, which are connected to reserves of said components, through ducts equipped with non-return valves, filling of the cylinders being possibly accelerated or provided by force feed pumps assigned to each of them.

However, if one of these cylinders is not completely full at the beginning of the delivery controlled by the actuator piston because more especially the product it contains is more viscous than the others and because filling of the corresponding cylinder is consequently slower, cavitation phenomena may occur such that the proportion of the product delivered by the cylinder in question is not the desired one.

Now, in accordance with the present invention, this disadvantage of pumps of the abovementioned known type for delivering several different products in well defined proportions may be avoided by completing them with means for allowing the piston of the actuator to slide in the delivery direction only if all the cylinders assigned to each of the components of the products to be mixed have been completely filled beforehand.

Summary of the Invention According to one embodiment of the present invention, particularly simple and reliable, this result is obtained by the fact that the connection between the piston of the actuator and those of the cylinders assigned to each of the components is automatically cut off as soon as the actuator piston begins its return stroke and is only reestablished for its delivery stroke after each of these cylinders has been completely filled; thus, switches may be assigned to each of the pistons of the cylinders assigned to the different products, these switches being arranged so that they are closed by the pistons of said product cylinders at the end of their filling strokes, caused for each of them by its force feed pump, and so that they only allow the delivery movement of the actuator piston to be controlled when they are all closed.

With such an arrangement, it is no longer necessary to slow down the suction speed of the piston of the actuator to be sure that the filling of the cylinders assigned to each constituent takes place perfectly; on the contrary, this rise may take place at high speed and its descent controlling the simultaneous flowrate of the different constituents of the product in the desired proportions may begin automatically, as soon as the cylinders have been suitably filled, the filling time is thus reduced to a minimum and depends only on the pressures and delivery rates of the force feed pumps.

Brief Description of the Drawings The enclosed drawings show schematically, by way of example, one embodiment of the present invention in the case where two products only are to be delivered in a given proportion.

Figure 1 shows the pump during the emptying period.

Figure 2 shows the same pump during the filling period.

Description of the Preferred Embodiment The pump shown comprises, in a way known per se, an actuator in the cylinder 1 of which may slide an appropriately controlled piston 2. Sliding of this piston is interlocked, through its rod 3 and a coupling bar 4, with those of the two pistons 5 and 6, with sections proportional to the desired flowrates for components 7 and 8, contained in cylinders 9 and 10 assigned to each of them.

Cylinders 9 and 10 are fed, through the filling ducts 11 and 12, with interpositioning on nonreturn valves 1 3 and 14, from reserves, not shown, of the above-mentioned two constituents, possibly by means of force feed pumps; it will be readily understood that, during its delivery stroke, in the direction shown by the arrow of figure 1, piston 2 causes equal sliding of pistons 5 and 6 in their cylinders 9 and 10 and, consequently, corresponding flowrates of products 7 and 8 through the delivery ducts 1 5 and 16, with interpositioning of non-return valves 1 7 and 18, towards the point of use.

The pump of the invention, such as shown, durther comprises means such that the piston 2 of actuator 1 is automatically uncoupled from psitons 5 and 6 of cylinders 9 and 10 assigned to each of the products 7 and 8 as soon as it begins its return stroke, in the direction shown by the arrow in figure 2, opposite that of the delivery.

Thus, cylinders 9 and 10 may be progressively and completely filled with the products 7 and 8 to which they are assigned, whatever the viscosities of these products, which may be different, under the effect of corresponding force feed pumps, not shown.

To prevent the piston 2 of actuator 1 from beginning its delivery stroke, in the direction of the arrow shown in figure 1, before the two cylinders 9 and 10 are completely filled and so that consequently one of them may begin to deliver before the other, two switches 19 and 20 may be provided, each assigned to one of pistons 5 and 6, adapted so that they do not allow the current controlling the delivery stroke of piston 2 to flow as long as they have not both been closed by pistons 5 and 6 at the end of their return stroke caused by filling thereof under the effect of force feed pumps.

It will of course be readily understood that the embodiment of the invention which has been described above with reference to the accompanying drawings has been given solely by way of indication and is in no wise limiting and that numerous modifications may be made thereto without departing for all that from the scope and spirit of the invention; thus, any other arrangement may be used such that the coupling of piston 2 of actuator 1 and of the pistons 5 and 6 of cylinders 9 and 10 can only take place when the two cylinders in question are completely filled and so that, on the other hand, uncoupling occurs automatically as soon as the piston 2 of actuator 1 begins its return stroke, or any other device limiting for example the speed of the return stroke of the piston of the actuator sufficiently to avoid any possibility of cavitation in the cylinders during filling, assigned to each of the products, whatever the viscosity thereof may be, allowing complete filling of each of said cylinders to be checked and only allowing the delivery stroke of said actuator piston if the means for checking the filling of the cylinders have ascertained that all these cylinders have been entirely filled beforehand.

Claims

1. A pump for delivering several different products in well defined proportions using a single actuator whose piston, during its delivery stroke, causes simultaneous sliding, by the same amount or by proportional amounts, of a number of pistons equal to that of the constituents of the mixture, which pistons have sections depending on the desired flowrate for each of these constituents in cylinders assigned to each of them, suitably controlled amounts of which may escape therefrom to the point of use through ducts having non-return valves whereas, during its return stroke, the piston of the above-mentioned actuator causes or allows simultaneous sliding, by the same amount or by proportional amounts, of these same pistons in the cylinders assigned to each of the components which are connected to reserves of said components, through ducts provided with non-return valves, the filling of these cylinders being able to be accelerated or caused by force feed pumps assigned to each of them, further comprising means for allowing the piston of the actuator to slide in the delivery direction only when all the cylinders assigned to each of the components of the products to be mixed have been completely filled beforehand.

2. The pump as claimed in claim 1, wherein means cause the piston of the actuator and the pistons of said cylinders assigned to each of said products to be automatically uncoupled as soon as the return stroke of said actuator piston begins, coupling together again of these pistons only being re-established after complete filling of said cylinders for the delivery stroke of said actuator piston.

3. The pump as claimed in any one of claims 1 and 2, wherein switches assigned to each of said pistons are adapted so that they do not allow the current controlling the delivery stroke of the actuator piston to flow as long as they have not both been closed by said pistons at the end of their rising stroke caused by filling thereof under the effect of force feed pumps.